Silicon-carbon material, and preparation method therefor and use thereof

Abstract

A silicon-carbon material, and a preparation method therefor and the use thereof. The silicon-carbon material comprises a reaction product of a silicon-based material and a carbon source, which carbon source is selected from one or more of a liquid carbon source, a solid carbon source and a gas carbon source, wherein the liquid carbon source is selected from one or more of a C6-C16 alkane, a C6-C12 aromatic hydrocarbon, a C1-C6 alcohol, naphtha, gasoline and diesel oil; the solid carbon source is selected from one or more of a C2-C6 polyolefin, polystyrene and biomass; and the gas carbon source is selected from one or more of a C1-C5 alkane and a C2-C5 olefin. By subjecting an insulating silicon-based material to conductivity modification, the resistivity and carbon content of the material can be effectively controlled, and the controllability of the process and the application scenarios of the material are improved.

Description

Silicon-carbon materials, preparation methods and applications of silicon-carbon materials

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application with application number 202310971226.5 filed on August 1, 2023, and invention name “Silicon-carbon materials, preparation methods and applications of silicon-carbon materials”. The entire contents of the above-mentioned Chinese patent application are incorporated into this application as a whole. Technical Field

[0003] The present application relates to the technical field of secondary battery materials, and in particular to a silicon-carbon material and a preparation method and application of the silicon-carbon material. Background Art

[0004] Conductive materials are a key driver of modern scientific and industrial development due to their widespread use in electronic devices, communications technology, energy, and materials science. Conductive materials are divided into two categories: metallic conductors and non-metallic conductors. The conductivity of metallic conductors comes from their free electrons, while the conductivity of non-metallic conductors comes from their electronic structure and chemical bonds. The physical properties of conductive materials are crucial to their performance and effectiveness in various applications. The most important of these are conductivity and stability. The conductive properties of conductive materials must meet requirements to support various operations and functions, such as processing information, converting signals, and storing data. Stability refers to the ability of a conductive material to maintain its electrical properties under different environments, such as high temperature resistance and corrosion resistance.

[0005] There are many ways to change the conductivity of materials, including material doping, interface modification, etc. Material doping is a commonly used method to change the conductivity of materials. During the doping process, some external impurities are introduced into the material. These impurities can increase the free carrier concentration of the material, thereby improving the conductivity of the material. The doped impurities can be anions or cations, such as boron, iron, phosphorus, etc. The advantages of doping are simple operation, low cost, and the ability to achieve uniform doping over a large area, thereby obtaining higher conductivity. The disadvantage is that doping may cause the destruction of the material's lattice structure, resulting in a decrease in the mechanical properties and stability of the material. Interface modification is a method of adjusting the conductivity of a material by changing the interaction between the material surface and the surrounding environment. For example, by modifying a layer of material with good conductivity on the surface of the material, the conductivity of the material can be improved. The advantage of interface modification is that the conductivity can be adjusted without changing the structure of the material itself. However, this method usually requires the preparation of complex materials and is relatively costly.

[0006] Methods for changing the conductive properties of insulating (low-conductivity) materials through interface modification include adding chemical modifiers to the surface of insulating materials or changing their surface chemical properties through surface modification techniques, thereby affecting the conductive properties of insulating materials. For example, coating a conductive polymer or metal film on the surface of a polymer insulating material can improve its conductive properties; introducing an intermediate layer at the contact point between the insulating material and the conductive material or changing its interface properties through surface chemical reactions can change the contact resistance between the insulating material and the conductive material, thereby affecting its conductive properties. For example, introducing a dielectric intermediate layer between a metal and a polymer can reduce the contact resistance and improve the conductivity; and changing the conductive properties of an insulating material by injecting ions into it. For example, injecting metal or carbon ions into a polymer material can form a conductive path, improving its conductive properties, etc.

[0007] By coating a material with a thin carbon film, its electrical conductivity can be modified. Carbon films have excellent electrical conductivity and chemical stability, forming a conductive layer on the surface of a material. This method is widely used to modify the conductivity of materials such as metals, ceramics, and polymers. For example, polymer dielectric materials treated with carbon coatings can improve their electrical conductivity and are widely used in electronic components.

[0008] Common methods for depositing carbon films on material surfaces include chemical vapor deposition (CVD) or physical vapor deposition (PVD). Chemical vapor deposition (CVD) uses the principle of gas phase reaction at high temperature to deposit a layer of highly conductive material on the surface of the material, thereby improving the conductivity of the overall material. For example, in the preparation of electronic components, chemical vapor deposition can be used to deposit metals or metal oxides on the surface of a semiconductor to form a conductive layer, thereby improving the performance and stability of the electronic components. However, chemical vapor deposition has obvious disadvantages: (1) The substrate surface must undergo complex cleaning and treatment to ensure the quality and uniformity of the deposited film. (2) The deposition rate is slow, and high temperature and a long time are required to form a thick film. (3) During the deposition process, the gases and evaporated substances generated may contaminate other equipment and the environment. (4) For some materials, vapor deposition is not applicable. For example, when depositing metal materials with high melting points, very high temperatures are required, which will lead to other problems, such as substrate thermal expansion, gas pressure, etc. (5) The quality of the deposited film is easily affected by process parameters such as temperature, gas flow rate, deposition rate, etc., so a lot of experiments and optimization are required to obtain the ideal film quality. (6) For some substrates with special shapes (such as pipes, spheres, etc.), vapor deposition cannot be effectively performed.

[0009] Physical vapor deposition (PVD) is another commonly used thin film deposition technique. It forms thin films by depositing a substance onto a substrate surface through the transformation of a solid state into a gaseous state (evaporation or sputtering). This method can be performed under atmospheric or reduced pressure. Commonly used gases include inert gases (such as helium and argon) or reactive gases (such as nitrogen and oxygen). The solid material used can be pure metals, alloys, compounds, and more. However, PVD requires expensive equipment and specialized techniques, resulting in high production costs. Furthermore, the use of specialized equipment such as vacuum chambers leads to high maintenance and repair costs. Furthermore, the vacuum required for evaporation and deposition results in low production efficiency. This means that large-scale production requires longer production times and higher energy consumption. Furthermore, PVD can only be used with materials with higher vapor pressures, limiting the range of applicable materials. In PVD, film thickness is often affected by many factors, such as substrate temperature and evaporation rate. Therefore, only relatively thin films can be produced. Furthermore, the use of vacuum equipment in PVD requires significant energy and generates significant amounts of waste gas and wastewater. These wastes require special treatment to avoid negative impacts on the environment.

[0010] Summary of the Invention

[0011] To address the aforementioned technical issues in the prior art, this application provides a silicon-carbon material and a method for preparing the same. The method provided herein modifies the electrical conductivity of insulating silicon-based materials, effectively controlling the resistivity and carbon content of the materials, improving process controllability and the material's application scenarios.

[0012] In a first aspect, the present application provides a silicon-carbon material, which includes a reaction product of a silicon-based material and a carbon source, wherein the carbon source is selected from one or more of a liquid carbon source, a solid carbon source and a gaseous carbon source, wherein the liquid carbon source is selected from one or more of C6-C16 alkanes, C6-C12 aromatic hydrocarbons, C1-C6 alcohols, naphtha, gasoline and diesel; the solid carbon source is selected from one or more of poly C2-C6 olefins, polystyrene and biomass; and the gaseous carbon source is selected from one or more of C1-C5 alkanes and C2-C5 olefins.

[0013] In some embodiments, the liquid carbon source is selected from one or more of C6-C16 straight-chain alkanes, C6-C16 branched-chain alkanes, C6-C16 cycloalkanes, C6-C10 aromatic hydrocarbons, C1-C6 monohydric alcohols, naphtha, gasoline and diesel.

[0014] In some embodiments, the liquid carbon source is selected from one or more of C6-C12 linear alkanes, C6-C12 cycloalkanes, C6-C8 aromatic hydrocarbons, C1-C4 monohydric alcohols, naphtha, gasoline and diesel.

[0015] The present application has no special requirements on the composition of naphtha, and any naphtha conventionally used in the art is suitable for the present application.

[0016] In some embodiments, the liquid carbon source is selected from one or more of naphtha, n-hexane, cyclohexane, n-heptane, cycloheptane, n-octane, cyclooctane, n-nonane, cyclononane, n-decane, cyclodecane, benzene, toluene, ethylbenzene, methanol, ethanol and propanol.

[0017] In some embodiments, the solid carbon source is selected from one or more poly C2-C4 olefins.

[0018] In some embodiments, the poly-C2-C4 olefin has a molecular weight ranging from 5,000 to 5,000,000 g / mol (5,000 to 5,000,000 g / mol), for example, 10,000 g / mol, 50,000 g / mol, 100,000 g / mol, 150,000 g / mol, 200,000 g / mol, 250,000 g / mol, 300,000 g / mol, 350,000 g / mol, 400,000 g / mol, 450,000 g / mol, 500,000 g / mol, 700,000 g / mol, 1,000,000 g / mol, 1,500,000 g / mol, 2,000,000 g / mol, 2,500,000 g / mol, 3,000,000 g / mol, 3,500,000 g / mol, 4,000,000 g / mol, or 4,500,000 g / mol. In some embodiments, the poly-C2-C6 olefin has a molecular weight ranging from 30,000 to 50,000 g / mol.

[0019] In some embodiments, the solid carbon source is selected from one or more of polyethylene, polypropylene, and polybutene.

[0020] In some embodiments, the gaseous carbon source is selected from C1-C4 straight-chain alkanes, C3-C5 branched alkanes, C3-C5 cycloalkanes, and C2-C5 straight-chain alkenes.

[0021] In some embodiments, the gaseous carbon source is selected from one or more of methane, ethane, n-propane, ethylene, and propylene.

[0022] In some embodiments, the particle size of the silicon-based material is 10 nm to 500 nm.

[0023] In some embodiments, the particle size of the silicon-based material is 30nm, 50nm, 70nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, 300nm, 310nm, 320nm, 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, 390nm, 400nm, 430nm, 450nm, 470nm or a range consisting of any value therebetween.

[0024] In the present application, the particle size of the silicon-based material is a value or range corresponding to the particle size of more than 90% of the silicon-based material particles.

[0025] In some embodiments, the particle size of the silicon-based material is 30 nm to 300 nm. In some embodiments, the particle size of the silicon-based material is 100 nm to 200 nm.

[0026] In some embodiments, the silicon-based material is selected from one or more of single crystal silicon, polycrystalline silicon, silicon oxide, silicon carbide, silicon monoxide, silicon dioxide, and silicate ceramics.

[0027] In some embodiments, the mass content of the carbon element is 10%-50%, such as 13%, 15%, 17%, 20%, 23%, 25%, 27%, 30%, 35%, 40% or 45%, based on the mass of the silicon-carbon material. In some embodiments, the mass content of the carbon element is 15%-30%, based on the mass of the silicon-carbon material.

[0028] In a second aspect, the present application provides a method for preparing a silicon-carbon material, which comprises reacting a silicon-based material with a carbon source under microwave treatment, wherein the carbon source is selected from one or more of a liquid carbon source, a solid carbon source and a gaseous carbon source, wherein the liquid carbon source is selected from one or more of C6-C16 alkanes, C6-C12 aromatic hydrocarbons, C1-C6 alcohols, naphtha, gasoline and diesel; the solid carbon source is selected from one or more of poly C2-C6 olefins, polystyrene and biomass; and the gaseous carbon source is selected from one or more of C1-C5 alkanes and C2-C5 olefins.

[0029] After extensive research, the inventors of this application discovered that the field effect provided by microwaves, rather than the heating effect, is a more crucial factor in determining specific reactions. The unique properties exhibited by the appropriate reaction system, conditions, and interactions with different materials are crucial factors in controlling reaction products, selectivity, and yield. This application addresses the coating of silicon-based materials with specific carbon sources under microwave treatment conditions, effectively controlling the material's resistivity and carbon content, broadening its application scenarios.

[0030] In some embodiments, the mass of the silicon-based material is Mg, and the power of the microwave treatment is NW, wherein M:N is 1:1 to 1:80, for example, 1:5, 1:10, 1:15, 1:20, 1:25, 1:26, 1:27, 1:28, 1:29, 1:30, 1:31, 1:32, 1:33, 1:34, 1:35, 1:36, 1:37, 1:38, 1:39, 1:40, 1:41, 1:42, 1:43, 1:44, 1:45, 1:46, 1:47, 1:78, 1:79, or any value therebetween. In some embodiments, the M:N is from 1:30 to 1:60.

[0031] In some embodiments, the power NW of the microwave treatment satisfies: N is greater than or equal to 1000. In some embodiments, N is 1300, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 10000, 11000, 12000, 13000, 15000, 17000, 20000, 23000, 25000, 27000, 30000, or any value therebetween. In some embodiments, N is greater than or equal to 2000. In some embodiments, 3000≤N≤8000. In some embodiments, 3500≤N≤6000.

[0032] In some embodiments, the liquid carbon source is selected from one or more of C6-C16 straight-chain alkanes, C6-C16 branched-chain alkanes, C6-C16 cycloalkanes, C6-C10 aromatic hydrocarbons, C1-C6 monohydric alcohols, naphtha, gasoline and diesel.

[0033] In some embodiments, the liquid carbon source is selected from one or more of C6-C12 linear alkanes, C6-C12 cycloalkanes, C6-C8 aromatic hydrocarbons, C1-C4 monohydric alcohols, naphtha, gasoline and diesel.

[0034] In some embodiments, the liquid carbon source is selected from one or more of naphtha, n-hexane, cyclohexane, n-heptane, cycloheptane, n-octane, cyclooctane, n-nonane, cyclononane, n-decane, cyclodecane, benzene, toluene, ethylbenzene, methanol, ethanol and propanol.

[0035] The present application has no special requirements on the composition of naphtha, and any naphtha conventionally used in the art is suitable for the present application.

[0036] In some embodiments, the solid carbon source is selected from one or more poly C2-C4 olefins.

[0037] In some embodiments, the poly-C2-C4 olefin has a molecular weight in the range of 5000-5,000,000 g / mol (5,000-5,000,000 g / mol), for example, 10,000 g / mol, 50,000 g / mol, 100,000 g / mol, 150,000 g / mol, 200,000 g / mol, 250,000 g / mol, 300,000 g / mol, 350,000 g / mol, 400,000 g / mol, 450,000 g / mol, 500,000 g / mol, 700,000 g / mol, 1,000,000 g / mol, 1,500,000 g / mol, 2,000,000 g / mol, 2,500,000 g / mol, 3,000,000 g / mol, 3,500,000 g / mol, 4,000,000 g / mol, or 4,500,000 g / mol.

[0038] In some embodiments, the poly C2-C6 olefin has a molecular weight in the range of 30,000-50,000 g / mol.

[0039] In some embodiments, the solid carbon source is selected from one or more of polyethylene, polypropylene, and polybutene.

[0040] In some embodiments, the gaseous carbon source is selected from C1-C4 straight-chain alkanes, C3-C5 branched alkanes, C3-C5 cycloalkanes, and C2-C5 straight-chain alkenes.

[0041] In some embodiments, the gaseous carbon source is selected from one or more of methane, ethane, n-propane, ethylene, and propylene.

[0042] In some embodiments, the particle size of the silicon-based material is 10 nm to 500 nm. In some embodiments, the particle size of the silicon-based material is 30 nm, 50 nm, 70 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 310 nm, 320 nm, 330 nm, 340 nm, 350 nm, 360 nm, 370 nm, 380 nm, 390 nm, 400 nm, 430 nm, 450 nm, 470 nm, or a range consisting of any value therebetween.

[0043] In the present application, the particle size of the silicon-based material is a value or range corresponding to the particle size of more than 90% of the silicon-based material particles.

[0044] In some embodiments, the particle size of the silicon-based material is 30 nm to 300 nm. In some embodiments, the particle size of the silicon-based material is 100 nm to 200 nm.

[0045] In some embodiments, the silicon-based material is selected from one or more of single crystal silicon, polycrystalline silicon, silicon oxide, silicon carbide, silicon monoxide, silicon dioxide, and silicate ceramics.

[0046] In some embodiments, when the carbon source is selected from a liquid carbon source or a solid carbon source, the mass content of the carbon source is greater than or equal to 50% based on the mass of the silicon-based material, for example, 100%, 130%, 170%, 190%, 200%, 210%, 230%, 250%, 270%, 290%, 300%, 350% or any value therebetween.

[0047] In some embodiments, the mass content of the carbon source is 150%-250%.

[0048] In some embodiments, when the carbon source is selected from a gaseous carbon source, the gaseous carbon source has a headspace velocity (GHSV) of 1 h -1 Up to 10,000 hours -1 , for example, 10h -1 , 20h -1 , 50h -1 , 70h -1 、100h -1 , 150h -1 , 200h -1 , 250h -1 , 300h -1 , 400h-1 , 500h -1 , 700h -1 、1000h -1 , 1500h -1 , 2000h -1 , 2500h -1 , 3000h -1 , 4000h -1 5000h -1 , 6000h -1 , 7000h -1 , 8000h -1 , 9000h -1 Or any value therebetween. In some embodiments, when the carbon source is selected from a gaseous carbon source, the volume space velocity of the gaseous carbon source is 30h -1 Up to 3000h -1 .

[0049] In some embodiments, when the carbon source is selected from a gaseous carbon source, the flow rate of the gaseous carbon source is 100 mL / min-100 L / min, for example, 150 mL / min, 200 mL / min, 250 mL / min, 300 mL / min, 350 mL / min, 400 mL / min, 450 mL / min, 500 mL / min, 700 mL / min, 900 mL / min, 1 L / min, 3 L / min, 5 L / min, 7 L / min, 10 L / min, 15 L / min, 20 L / min, 30 L / min, 40 L / min, 50 L / min, 60 L / min, 70 L / min, 80 L / min, 90 L / min or any value therebetween. In some embodiments, when the carbon source is selected from a gaseous carbon source, the flow rate of the gaseous carbon source is 1 L / min-10 L / min.

[0050] In some embodiments, when the carbon source is selected from a liquid carbon source or a solid carbon source, the silicon-based material is reacted with the preheated carbon source under microwave treatment. In some embodiments, the temperature of the preheated carbon source is 100°C to 450°C, for example, 120°C, 150°C, 170°C, 200°C, 230°C, 250°C, 270°C, 300°C, 330°C, 350°C, 370°C, 400°C, or 430°C. In some embodiments, the preheating is performed in a preheating furnace.

[0051] In the present application, by preheating the liquid carbon source or the solid carbon source, the liquid carbon source or the solid carbon source can be brought into more complete contact with the material, thereby avoiding sintering.

[0052] The present application has no special requirements on the composition of naphtha, and any naphtha conventionally used in the art is suitable for the present application.

[0053] In some embodiments, the reaction is carried out under standard atmospheric pressure and an oxygen content of less than 5000 ppm, for example, the reaction is carried out under an inert atmosphere. In this application, an inert atmosphere is a nitrogen atmosphere or an argon atmosphere.

[0054] In some embodiments, the reaction temperature is 300° C.-750° C., for example, 320° C., 350° C., 370° C., 400° C., 420° C., 450° C., 470° C., 500° C., 530° C., 550° C., 570° C., 600° C., 630° C., 650° C., 670° C., 700° C., 730° C., or any value therebetween. In some embodiments, the reaction temperature is 400° C.-600° C.

[0055] In some embodiments, the reaction is carried out in a microwave reactor. In some embodiments, the microwave reactor is provided with a microwave source to provide microwaves. In some embodiments, the microwave source comprises a magnetron or a solid-state source. In some embodiments, the frequency used in the microwave treatment is 2.45 GHz or 915 MHz.

[0056] In some embodiments, when the carbon source is selected from a liquid carbon source or a solid carbon source, the method for preparing the silicon-carbon material comprises the following steps:

[0057] M1: putting silicon-based materials into a microwave reactor;

[0058] M2: Add excess carbon source to the raw material bottle of the preheating furnace (to prevent the raw material from running out and bringing air into the reactor), and connect the raw material bottle to the peristaltic pump, ensuring that the furnace body is locked;

[0059] M3: Connect the protective gas (nitrogen or argon) and check the tightness of the reaction system. After the inspection, use the protective gas to purge the air and exhaust the air in the reaction system;

[0060] M4: After the reaction system is purged, the preheating furnace is turned on in the presence of protective gas, and naphtha is pumped from the raw material bottle into the preheating furnace;

[0061] M5: After the carbon source reaches the target temperature, the carbon source is transported to the microwave reactor, and the microwave reactor is turned on to react.

[0062] In some embodiments, the method further includes M6: after the reaction is completed, taking the material, performing a sample resistivity test on the material, and repeating steps M1 to M5 on the sample according to the resistivity value until the material resistivity meets the requirement.

[0063] In some embodiments, when the carbon source is selected from a liquid carbon source or a solid carbon source, the method for preparing the silicon-carbon material comprises the following specific steps:

[0064] (1) Put the silicon-based material into a microwave reactor, seal it, and connect it to the carbon source preheating system.

[0065] (2) Add excess carbon source to the raw material bottle of the preheating furnace (to prevent the raw material from running out and bringing air into the reactor), and connect the raw material bottle to the peristaltic pump to ensure that the furnace body is locked;

[0066] (3) Connect the protective gas (nitrogen or argon) and check the airtightness of the reaction system. After the inspection, increase the protective gas flow rate to 300 mL / min to purge the air and exhaust the air in the reaction system.

[0067] (4) Set the preheating furnace heating rate to 10°C / min and heat to 100°C-400°C;

[0068] (5) setting the microwave reactor program, for example, setting a constant power mode, wherein the power is set to 2000 W-8000 W and the constant temperature is set to 350° C.-750° C.;

[0069] (6) Adjust the carrier gas (protective gas) flow rate to 150 mL / min, start the preheating furnace, and start the operation. After the preheating furnace is actually heated to 240°C, start the peristaltic pump and start pumping the carbon source into the preheating furnace. Turn on the chiller and start the microwave reactor after the actual temperature of the preheating furnace reaches the target temperature.

[0070] (7) Control the carbon source oil feed rate. After the feed is completed, turn off the peristaltic pump, stop the preheating furnace, and turn off the auxiliary heating device. The microwave reactor continues to operate for 10-60 minutes before stopping.

[0071] In some embodiments, the method further comprises (8) cooling the instrument after stopping the microwave reactor, opening the microwave reactor after cooling, closing the carrier gas, and taking the material.

[0072] (9) Conduct resistivity test on sampled materials.

[0073] (10) Repeat steps (1) to (8) for the sample according to the resistivity value until the material resistivity meets the requirements.

[0074] In some embodiments, when the carbon source is selected from a gaseous carbon source, the method for preparing the silicon-carbon material comprises the following steps:

[0075] N1: putting silicon-based materials into a microwave reactor;

[0076] N2: Connect the protective gas (nitrogen or argon) and check the tightness of the reaction system. After the inspection, use the protective gas to purge the air and exhaust the air in the reaction system;

[0077] N3: After the reaction system is purged, a carbon source is introduced into the microwave reactor in the presence of protective gas and the microwave reactor is turned on to carry out the reaction.

[0078] In some embodiments, the method further includes N4: after the reaction is completed, taking the material, performing a sample resistivity test on the material, and repeating steps N1 to N3 on the sample according to the resistivity value until the material resistivity meets the requirement.

[0079] In some embodiments, when the carbon source is selected from a gaseous carbon source, the method for preparing the silicon-carbon material comprises the following steps:

[0080] (1) Put the silicon-based material into a microwave reactor and perform sealing treatment;

[0081] (2) Connect the protective gas (nitrogen or argon) and check the airtightness of the reaction system. After the inspection, increase the protective gas flow rate to 300 mL / min to purge the air and exhaust the air in the reaction system.

[0082] (3) Setting the microwave reactor program: for example, setting the mode to constant temperature mode, wherein the power is set to 2000W-8000W, and the constant temperature is set to 350°C-750°C;

[0083] (4) Mix the carbon source into the protective gas nitrogen, control the flow rate to, for example, 150 mL / min, and turn on the intermediate auxiliary heating device; calculate the reaction gas velocity every ten minutes using a stopwatch and flow rate display number and record the gas velocity, time and other experimental phenomena;

[0084] (5) After a certain reaction time, for example, 90 minutes, the microwave reactor is turned off. The stop time and flow rate display are recorded and the total gas production is calculated.

[0085] In some embodiments, the method further comprises (6) cooling the instrument after stopping the microwave reactor, opening the flange of the microwave reactor after cooling, closing the carrier gas, taking the material, and performing a sample resistivity test on the material;

[0086] In some embodiments, the method further includes (7) repeating steps (1) to (6) on the sample according to the resistivity value until the material resistivity reaches the requirement.

[0087] In some embodiments, the method further comprises ball milling and screening the qualified material according to requirements to meet the required material particle size.

[0088] In a third aspect, the present application provides an application of the silicon-carbon material described in the first aspect or the silicon-carbon material prepared by the preparation method described in the second aspect in a secondary battery.

[0089] In some embodiments, the application is application in secondary battery negative electrode materials.

[0090] In some embodiments, the negative electrode material of the secondary battery includes the silicon-carbon material described in the first aspect of the present application or the silicon-carbon material prepared by the preparation method described in the second aspect.

[0091] Beneficial technical effects of this application:

[0092] Due to the fundamental difference in mechanism between this application and traditional heating methods, it can form a uniform and highly conductive carbon layer on the surface of the silicon material. The resulting carbon layer has a higher degree of graphitization than traditional methods. In addition, the highly conductive and highly graphitized carbon layer allows the material to achieve a lower carbon content while also having higher conductivity. DETAILED DESCRIPTION

[0093] To make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the embodiments. The specific embodiments described herein are only used to explain this application and are not intended to constitute any limitation to this application.

[0094] Example 1

[0095] (1) Weigh 100 g of silicon material (single crystal silicon) with a particle size of 100 nm to 200 nm and put it into a microwave reactor and push it into a complete cylindrical bed. Seal the lid of the microwave reactor;

[0096] (2) Place 250 g of naphtha (isomeric D60, Shanghai Rongfu New Energy Technology Co., Ltd.) into the raw material bottle of the preheating furnace, connect the raw material bottle to the peristaltic pump, and ensure that the flange of the tubular furnace is tightened with screws; cover the microwave reactor and the upper cover of the tubular furnace;

[0097] (3) Leak detection: Connect nitrogen as the protective gas, adjust the preheating furnace gas flow meter to 300mL / min and observe whether there are bubbles in the tail gas bottle. If there are bubbles in the tail gas bottle, gradually reduce the preheating furnace gas flow meter to 30mL / min. If there are still bubbles, it proves that there is no leakage in other parts of the equipment except the outlet end;

[0098] (4) After leak detection, increase the nitrogen flow rate to 300 mL / min and perform gas washing for 30 minutes to exhaust the air inside;

[0099] (5) Set the preheating furnace heating program to: (heating rate is 10℃ / min);

[0100] (6) Set the peristaltic pump to 0.8 rpm and calibrate the flow rate to 0.5 g / min;

[0101] (7) Set the microwave reactor program: the mode is constant temperature mode, the constant temperature is set to 550 °C, and the microwave power is set to 4000 W;

[0102] (8) Adjust the N2 flow rate to 150 mL / min, start the preheating furnace and turn on the intermediate auxiliary heating device;

[0103] (9) After the preheating furnace is heated to 240°C, the peristaltic pump is turned on to start pumping in naphtha;

[0104] (10) Turn on the chiller, wait until the actual temperature of the preheating furnace rises to 300°C, turn on the microwave reactor, and use a stopwatch and flow meter to calculate the reaction gas velocity every ten minutes and record the gas velocity, time and other experimental phenomena;

[0105] (11) When the amount of liquid material is close to 200 g, turn off the peristaltic pump, stop the preheating furnace, turn off the intermediate auxiliary heating device, and keep the microwave reactor in operation for 30 minutes before stopping. At this time, record the stop time and flow rate display number, and calculate the total gas production;

[0106] (12) After stopping the microwave reactor, cool the instrument down, open the microwave reactor flange, turn off the carrier gas, and take the material. Perform a sample resistivity test on the material (see Table 1 for specific resistance values).

[0107] Example 2-Example 6

[0108] The only difference between Examples 2 to 6 and Example 1 is that different types of liquid carbon sources are used. The test results of the prepared silicon-carbon materials are shown in Table 1.

[0109] Among them, when the carbon source is n-hexane and cyclohexane, the preheating furnace program is

[0110] When the carbon source is benzene, the preheating furnace program is

[0111] When the carbon source is methanol, the preheating furnace program is

[0112] When the carbon source is ethanol, the preheating furnace program is

[0113] In the table, carbon content refers to the mass content of carbon element in the prepared silicon-carbon material.

[0114] Yield refers to the conversion rate of the carbon source, that is, yield = (mass of material after treatment - mass of material before treatment) / amount of carbon source used.

[0115] Table 1

[0116] Example 7

[0117] (1) Weigh 100 g of silicon material (single crystal silicon) with a particle size of 100 nm to 200 nm and put it into a microwave reactor and push it into a complete cylindrical bed. Seal the lid of the microwave reactor;

[0118] (2) Place 100 g of polyethylene plastic pellets (molecular weight 30,000-50,000 g / mol) in the preheating furnace, ensure that the tube furnace flange is tightened with screws; cover the microwave reactor and the tube furnace cover;

[0119] (3) Leak detection: Connect nitrogen as the protective gas, adjust the preheating furnace gas flow meter to 300mL / min and observe whether there are bubbles in the tail gas bottle. If there are bubbles in the tail gas bottle, gradually reduce the muffle furnace gas flow meter to 30mL / min. If there are still bubbles, it proves that there is no leakage in other parts of the equipment except the outlet end;

[0120] (4) After leak detection, increase the nitrogen flow rate to 300 mL / min and perform gas washing for 30 minutes to exhaust the air inside;

[0121] (5) Set the preheating furnace heating program to The heating rate is 10°C / min;

[0122] (6) Set the microwave reactor program: the mode is constant temperature mode, the constant temperature is set to 550 °C, and the microwave power is set to 4000 W;

[0123] (7) Adjust the N2 flow rate to 150 mL / min, start the preheating furnace and turn on the intermediate auxiliary heating device;

[0124] (8) After the actual temperature of the preheating furnace rises to 300°C, start the microwave reactor and use a stopwatch and flow meter to calculate the reaction gas velocity every ten minutes and record the gas velocity, time and other experimental phenomena;

[0125] (9) After 60 minutes of reaction (to ensure complete reaction of the plastic particles), the preheating furnace is stopped and the intermediate auxiliary heating device is turned off. The microwave reactor is kept in operation for 30 minutes and then stopped. At this time, the stop time and flow rate display number are recorded to calculate the total gas production;

[0126] (10) After stopping the microwave reactor, the instrument was cooled down. The microwave reactor flange was opened after cooling down, the carrier gas was turned off, the material was taken out, and the resistivity of the sample was tested. The specific resistance values ​​are shown in Table 2.

[0127] Example 8 to Example 12

[0128] The only difference between Examples 8 to 12 and Example 7 is that the type of carbon source and the mass of the added carbon source are adjusted. The test results of the prepared silicon-carbon materials are detailed in Table 2.

[0129] Table 2

[0130] Example 13

[0131] (1) Weigh 100 g of silicon material (single crystal silicon) with a particle size of 100 nm to 200 nm and put it into a microwave reactor and push it into a complete cylindrical bed. Seal the lid of the microwave reactor;

[0132] (2) Connect nitrogen as the protective gas, adjust the gas flow meter to 300mL / min and observe whether there are bubbles in the tail gas bottle. If there are bubbles in the tail gas bottle, gradually reduce the gas flow meter to 30mL / min. If there are still bubbles, it proves that there is no leakage in other parts of the equipment except the outlet;

[0133] (3) After leak detection, increase the nitrogen flow rate to 300 mL / min and perform gas washing for 30 minutes to exhaust the air inside;

[0134] (4) Set the microwave reactor program: the mode is constant temperature mode, the constant temperature is set to 550 °C, and the microwave power is set to 4000 W;

[0135] (5) 20% of the raw gas methane was mixed into the protective gas nitrogen, and the flow rate was controlled at 150 mL / min. The intermediate auxiliary heating device was turned on. The reaction gas velocity was calculated every ten minutes using a stopwatch and flow meter, and the gas velocity, time, and other experimental phenomena were recorded.

[0136] (6) After 90 minutes of reaction, the microwave reactor was turned off, and the stop time and flow rate reading were recorded to calculate the total gas production;

[0137] (7) After stopping the microwave reactor, cool the instrument down, open the microwave reactor flange, turn off the carrier gas, take the material, and perform a sample resistivity test on the material. The specific resistance values ​​are shown in Table 3.

[0138] Example 14 to Example 15

[0139] The only difference between Examples 14 and 15 and Example 13 is that the type of carbon source is adjusted. The test results of the prepared silicon-carbon materials are detailed in Table 3.

[0140] Table 3

[0141] Example 16

[0142] (1) Weigh 100 g of silicon material (single crystal silicon) with a particle size of 100 nm to 200 nm and put it into a microwave reactor and push it into a complete cylindrical bed. Seal the lid of the microwave reactor.

[0143] (2) Place 250 g of naphtha (isomeric D60, Shanghai Rongfu New Energy Technology Co., Ltd.) into the raw material bottle of the preheating furnace, connect the raw material bottle to the peristaltic pump, and ensure that the flange of the tubular furnace is tightened with screws; cover the microwave reactor and the upper cover of the tubular furnace;

[0144] (3) Leak detection: Connect nitrogen as the protective gas, adjust the preheating furnace gas flow meter to 300mL / min and observe whether there are bubbles in the tail gas bottle. If there are bubbles in the tail gas bottle, gradually reduce the muffle furnace gas flow meter to 30mL / min. If there are still bubbles, it proves that there is no leakage in other parts of the equipment except the outlet end;

[0145] (4) After leak detection, increase the nitrogen flow rate to 300 mL / min and perform gas washing for 30 minutes to exhaust the air inside;

[0146] (5) Set the preheating furnace heating program to: (heating rate is 10℃ / min);

[0147] (6) Set the peristaltic pump to 0.8 rpm and calibrate the flow rate to 0.5 g / min;

[0148] (7) Set the microwave reactor program: the mode is constant temperature mode, the constant temperature is set to 550 °C, and the microwave power is set to 4000 W;

[0149] (8) Adjust the N2 flow rate to 150 mL / min, start the preheating furnace and turn on the intermediate auxiliary heating device;

[0150] (9) After the preheating furnace is heated to 240°C, the peristaltic pump is turned on to start pumping in naphtha;

[0151] (10) Turn on the chiller, wait until the actual temperature of the preheating furnace rises to 300°C, turn on the microwave reactor, and use a stopwatch and flow meter to calculate the reaction gas velocity every ten minutes and record the gas velocity, time and other experimental phenomena;

[0152] (11) When the amount of liquid material is close to 200 g, turn off the peristaltic pump, stop the preheating furnace, turn off the intermediate auxiliary heating device, and keep the microwave reactor in operation for 30 minutes before stopping. At this time, record the stop time and flow rate display number, and calculate the total gas production;

[0153] (12) After stopping the microwave reactor, the instrument was cooled down. The microwave reactor flange was opened after cooling down, the carrier gas was turned off, the material was taken out, and the resistivity of the sample was tested. The specific resistance values ​​are shown in Table 4.

[0154] Example 17 to Example 23

[0155] The only difference between Examples 17 to 23 and Example 16 is that the reaction temperature and microwave power are adjusted. The test results of the prepared silicon-carbon materials are shown in Table 4.

[0156] Table 4

[0157] Example 24

[0158] In this example, silicon material (single crystal silicon) with a particle size of 100-200 nm was selected, and naphtha (isomeric D60, Shanghai Rongfu New Energy Technology Co., Ltd.) was used as the carbon source to explore the effect of the carbon content of the silicon material on its conductivity. The specific process method is as follows:

[0159] (1) Weigh 100 g of silicon material and put it into a microwave reactor and push it into a complete cylindrical bed. Seal the lid of the microwave reactor;

[0160] (2) Place 250 g of naphtha in the raw material bottle of the preheating furnace, connect the raw material bottle to the peristaltic pump, and ensure that the flange of the tube furnace is tightened with screws; cover the microwave reactor and the upper cover of the tube furnace;

[0161] (3) Leak detection: Connect nitrogen as the protective gas, adjust the preheating furnace gas flow meter to 300mL / min and observe whether there are bubbles in the tail gas bottle. If there are bubbles in the tail gas bottle, gradually reduce the preheating furnace gas flow meter to 30mL / min. If there are still bubbles, it proves that there is no leakage in other parts of the equipment except the outlet end;

[0162] (4) After leak detection, increase the nitrogen flow rate to 300 mL / min and perform gas washing for 30 minutes to exhaust the air inside;

[0163] (5) Set the preheating furnace heating program to: (heating rate is 10℃ / min);

[0164] (6) Set the peristaltic pump to 0.8 rpm and calibrate the flow rate to 0.5 g / min;

[0165] (7) Set the microwave reactor program: the mode is constant temperature mode, the constant temperature is set to 550 °C, and the microwave power is set to 4000 W;

[0166] (8) Adjust the N2 flow rate to 150 mL / min, start the preheating furnace and turn on the intermediate auxiliary heating device;

[0167] (9) After the preheating furnace is heated to 240°C, the peristaltic pump is turned on to start pumping in naphtha;

[0168] (10) Turn on the chiller, wait until the actual temperature of the preheating furnace rises to 300°C, turn on the microwave reactor, and use a stopwatch and flow meter to calculate the reaction gas velocity every ten minutes and record the gas velocity, time and other experimental phenomena;

[0169] (11) When the amount of liquid material is close to 200 g, turn off the peristaltic pump, stop the preheating furnace, turn off the intermediate auxiliary heating device, and keep the microwave reactor in operation for 30 minutes before stopping. At this time, record the stop time and flow rate display number, and calculate the total gas production;

[0170] (12) After stopping the microwave reactor, cool the instrument, open the microwave reactor flange, turn off the carrier gas, take the material, and perform a sample resistivity test on the material;

[0171] (13) Repeat steps (1) to (12) to change the carbon content of the material and sample and test the resistivity of the material.

[0172] Table 5

[0173] The technical solution of the present application is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present application fall within the protection scope of the present application.

Claims

1. A silicon-carbon material comprising a reaction product of a silicon-based material and a carbon source, wherein the carbon source is selected from one or more of a liquid carbon source, a solid carbon source and a gaseous carbon source, wherein: The liquid carbon source is selected from one or more of C6-C16 alkanes, C6-C12 aromatic hydrocarbons, C1-C6 alcohols, naphtha, gasoline and diesel; The solid carbon source is selected from one or more of poly C2-C6 olefins, polystyrene and biomass; The gaseous carbon source is selected from one or more of C1-C5 alkanes and C2-C5 alkenes.

2. The silicon-carbon material according to claim 1, characterized in that: The liquid carbon source is selected from one or more of C6-C16 straight-chain alkanes, C6-C16 branched-chain alkanes, C6-C16 cycloalkanes, C6-C10 aromatic hydrocarbons, C1-C6 monohydric alcohols, naphtha, gasoline and diesel, preferably selected from one or more of C6-C12 straight-chain alkanes, C6-C12 cycloalkanes, C6-C8 aromatic hydrocarbons, C1-C4 monohydric alcohols, naphtha, gasoline and diesel, more preferably selected from one or more of naphtha, n-hexane, cyclohexane, n-heptane, cycloheptane, n-octane, cyclooctane, n-nonane, cyclononane, n-decane, cyclodecane, benzene, toluene, ethylbenzene, methanol, ethanol and propanol; and / or The solid carbon source is selected from one or more of poly C2-C4 olefins, preferably one or more of polyethylene, polypropylene and polybutene; and / or The gaseous carbon source is selected from C1-C4 straight-chain alkanes, C3-C5 branched alkanes, C3-C5 cycloalkanes, C2-C5 straight-chain olefins, and is preferably selected from one or more of methane, ethane, n-propane, ethylene and propylene.

3. The silicon-carbon material according to claim 1 or 2, characterized in that: The particle size of the silicon-based material is 10 nm to 500 nm, preferably 30 nm to 300 nm, more preferably 100 nm-200 nm; and / or The silicon-based material is selected from one or more of single crystal silicon, polycrystalline silicon, silicon oxide, silicon carbide, silicon monoxide, silicon dioxide and silicate ceramics.

4. A method for preparing a silicon-carbon material, comprising reacting a silicon-based material with a carbon source under microwave treatment, wherein the carbon source is selected from one or more of a liquid carbon source, a solid carbon source and a gaseous carbon source, wherein: The liquid carbon source is selected from one or more of C6-C16 alkanes, C6-C12 aromatic hydrocarbons, C1-C6 alcohols, naphtha, gasoline and diesel; The solid carbon source is selected from one or more of poly C2-C6 olefins, polystyrene and biomass; The gaseous carbon source is selected from one or more of C1-C5 alkanes and C2-C5 alkenes.

5. The preparation method according to claim 4, characterized in that: The mass of the silicon-based material is Mg, and the power of the microwave treatment is NW, wherein M:N is 1:1 to 1:80, preferably 1:30 to 1:

60.

6. The preparation method according to claim 4 or 5, characterized in that: The power NW of the microwave treatment satisfies: N is greater than or equal to 1000, preferably N is greater than or equal to 2000, and more preferably 3000≤N≤8000.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The liquid carbon source is selected from one or more of C6-C16 straight-chain alkanes, C6-C16 branched-chain alkanes, C6-C16 cycloalkanes, C6-C10 aromatic hydrocarbons, C1-C6 monohydric alcohols, naphtha, gasoline and diesel, preferably selected from one or more of C6-C12 straight-chain alkanes, C6-C12 cycloalkanes, C6-C8 aromatic hydrocarbons, C1-C4 monohydric alcohols, naphtha, gasoline and diesel, more preferably selected from one or more of naphtha, n-hexane, cyclohexane, n-heptane, cycloheptane, n-octane, cyclooctane, n-nonane, cyclononane, n-decane, cyclodecane, benzene, toluene, ethylbenzene, methanol, ethanol and propanol; and / or The solid carbon source is selected from one or more of poly C2-C4 olefins, preferably one or more of polyethylene, polypropylene and polybutene; and / or The gaseous carbon source is selected from C1-C4 straight-chain alkanes, C3-C5 branched alkanes, C3-C5 cycloalkanes, C2-C5 straight-chain olefins, preferably one or more selected from methane, ethane, n-propane, ethylene and propylene; and / or The particle size of the silicon-based material is 10 nm to 500 nm, preferably 30 nm to 300 nm, more preferably 100 nm-200 nm; and / or The silicon-based material is selected from one or more of single crystal silicon, polycrystalline silicon, silicon oxide, silicon carbide, silicon monoxide, silicon dioxide and silicate ceramics.

8. The preparation method according to any one of claims 4 to 7, characterized in that: When the carbon source is selected from a liquid carbon source or a solid carbon source, the mass content of the carbon source is greater than or equal to 50%, preferably 150%-250%, based on the mass of the silicon-based material; When the carbon source is selected from a gaseous carbon source, the volume space velocity of the gaseous carbon source is 1h -1 Up to 10,000h -1 , preferably 30h -1 Up to 3000h -1 .

9. The preparation method according to any one of claims 4 to 8, characterized in that: When the carbon source is selected from a liquid carbon source or a solid carbon source, the silicon-based material and the preheated carbon source are reacted under microwave treatment, preferably, the temperature of the preheated carbon source is 100° C.-450° C.; And / or, the reaction is carried out under an inert atmosphere, and the reaction temperature is 300°C-750°C, preferably 400°C-600°C.

10. Use of the silicon-carbon material according to any one of claims 1 to 3 or the silicon-carbon material prepared by the preparation method according to any one of claims 4 to 9 in a secondary battery, preferably a secondary battery negative electrode material.

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