Silicon carbon composite material, its manufacturing method, anode and battery

Abstract

The present disclosure provides a silicon-carbon composite material, a manufacturing method thereof, an anode, and a battery, particularly related to the battery technical field. The silicon-carbon composite material comprises silicon-carbon composite particles, each of which includes a C / C porous composite material and silicon nanoparticles located within and on the surface of the pores of the C / C porous composite material. The C / C porous composite material includes a first carbon material and a second carbon material, the first carbon material being a porous carbon substrate, and the second carbon material permeating the interior of the C / C porous composite material and also permeating the silicon-carbon composite material. The silicon-carbon composite material provided by the present disclosure is manufactured by introducing the second carbon material to form a conductive network structure with strength and toughness between the C / C porous composite material and the silicon nanoparticles, thereby preventing separation between the silicon and the carbon substrate during volume change, improving the electronic and ionic conductivity of the silicon-carbon composite material and extending the service life of the material.

Description

[Technical Field]

[0001] The present application relates to the field of battery technology, and in particular to silicon carbon composite materials, methods for producing the same, anodes and batteries.

[0002] This application claims priority to application number 202311154535X, filed with the State Intellectual Property Office of China on September 7, 2023, entitled "Silicon carbon composite material, manufacturing method thereof, anode and battery," the entire contents of which are incorporated herein by reference. [Background technology]

[0003] In recent years, the performance of silicon anodes has been improving, and the industrialization of Si / C composite anode materials is desired, but there is still room for further improvement in the performance of silicon anodes in various aspects.

[0004] Silicon anodes are characterized by their high specific energy, but they also undergo enormous volume expansion (approximately 300%) and contraction during the charge and discharge process. By combining carbon and silicon materials, it is possible to alleviate the volume change of silicon during the lithium insertion and desorption process to some extent. However, as the volume of silicon repeatedly expands and contracts, the silicon and carbon tend to separate, and they may no longer be in contact. However, the intrinsic electronic conductivity of silicon is low, at only 10 -5 ~10 -3 The lithium ion diffusion coefficient is also low, at 10 -14 ~10 -13 cm 2 This leads to deterioration of the structure and topography of the silicon carbon composite material and an increase in the internal resistance of the battery, resulting in problems such as a decrease in the battery's energy density, a decrease in voltage and power, and battery overheating.

[0005] In view of this, the present disclosure has been proposed. Summary of the Invention

[0006] The first objective of the present disclosure is to provide a silicon-carbon composite material for solving the problems of separation between silicon and carbon due to repeated expansion and contraction of silicon materials in the prior art, and deterioration of the structural stability and electrochemical performance of silicon-carbon composite materials.

[0007] The second objective of the present disclosure is to provide a manufacturing method for silicon-carbon composite materials.

[0008] The third objective of the present disclosure is to provide a negative electrode.

[0009] The third objective of the present disclosure is to provide a battery.

[0010] To achieve the above objectives of the present disclosure, the following technical solutions are particularly adopted.

[0011] The first aspect of the present disclosure provides a silicon-carbon composite material composed of silicon-carbon composite material particles. The silicon-carbon composite material particles include a C / C composite porous material and silicon nanoparticles located inside and on the surface of the pores of the C / C composite porous material. The C / C composite porous material includes a first carbon material and a second carbon material. The first carbon material is a porous carbon matrix, and the second carbon material penetrates through the inside of the C / C composite porous material and further penetrates through the silicon-carbon composite material. The dimension of the second carbon material in at least one dimension is greater than 100 nm.

[0012] Furthermore, the proportion of the second carbon material in the C / C composite porous material is 0.01 - 10 wt.%, and the second carbon material includes at least one of carbon nanotubes, graphene, carbon black, and carbon fibers.

[0013] Furthermore, the dimension of the second carbon material in the first dimension is L, satisfying 100 nm < L < 100 μm, and the dimension of the second carbon material in the second dimension is a, satisfying 0 < a < 20 nm.

[0014] Furthermore, L satisfies 100 nm < L < 20 μm, and a satisfies 0 < a < 10 nm.

[0015] Furthermore, the consolidated specific surface area of the silicon-carbon composite material is 1 to 20 times, preferably 1 to 10 times, and more preferably 1 to 5 times the specific surface area of the silicon-carbon composite material.

[0016] Furthermore, the pore volume of the C / C composite porous material is 0.2 to 3.0 cm 3 / g, and the volume ratio of micropores is greater than 50%.

[0017] Furthermore, the pore volume of the C / C composite porous material is 0.4 to 1.5 cm 3 / g, and the volume ratio of micropores is greater than 70%.

[0018] Furthermore, the diameter of the silicon nanoparticles is 0.5 to 5 nm, and furthermore, the content of silicon in the silicon-carbon composite material is 5 to 80 wt.%.

[0019] Furthermore, the silicon-carbon composite material further contains a heteroatom X located in the pores of the C / C composite porous material. The heteroatom X includes at least one of B, N, P, O, and S. The heteroatom X forms a Si-X chemical bond with the silicon atoms in the silicon nanoparticles and separates and encapsulates the silicon nanoparticles.

[0020] Furthermore, the content of the heteroatom in the silicon-carbon composite material is 0 to 10 wt.%.

[0021] Furthermore, the surface of the silicon-carbon composite material particles has a coating layer. Preferably, the material of the coating layer on the surface is one or more selected from solid electrolytes, conductive polymers, carbonaceous materials, metals, alloys, metal oxides, metal halides, metal sulfides, metal phosphates, borates, sulfates, nitrates, and polyoxometalates.

[0022] Furthermore, the surface of the silicon carbon composite particle has a coating layer with a lattice structure, and the material of the coating layer preferably includes at least one of carbon nanotubes, graphene, carbon black, and carbon fiber.

[0023] Furthermore, the specific surface area of ​​the silicon carbon composite material is 0.1 to 50 m 2 / g, and the pore volume is 0.01 to 0.5 cm 3 / g.

[0024] Furthermore, the specific surface area of ​​the silicon carbon composite material is 0.1 to 10 m 2 / g, and the pore volume is 0.01 to 0.1 cm 3 / g.

[0025] Furthermore, the true density of the silicon carbon composite material is 1.3 to 2.0 g / cm 3 The closed pore volume is 0.01 to 0.25 cm 3 / g.

[0026] A second aspect of the present disclosure provides a method for producing a silicon-carbon composite material. Step S1: Provide a C / C porous composite material containing a first carbon material and a second carbon material, where the first carbon material is a porous carbon substrate and the second carbon material perforates the interior of the C / C porous composite material and also perforates the silicon-carbon composite material. Step S2: Contact a silicon-containing precursor with the C / C porous composite material and perform chemical vapor deposition to distribute silicon nanoparticles within the pores and on the surface of the C / C porous composite material, thereby obtaining the silicon-carbon composite material. The C / C porous composite material, the first carbon material, the second carbon material, and the silicon nanoparticles have the same meanings as in the first aspect.

[0027] Furthermore, the method for producing the C / C composite porous material includes introducing a second carbon material into at least one of different manufacturing steps in the production process of the porous carbon material, and the manufacturing steps include a carbon precursor step, a carbon precursor pre-stabilization step, a carbonization step, a further pore-forming step, and a finished carbon material step.

[0028] Preferably, a first carbon material precursor and a second carbon material are mixed, and the mixture is sintered in an inert atmosphere or a mixed atmosphere of an inert gas and an oxygen-containing gas to obtain a C / C composite porous material; alternatively, a first carbon material precursor is sintered in an inert atmosphere to obtain a first carbon material, and the first carbon material and a second carbon material are mixed, and the mixture is sintered to obtain a C / C composite porous material, wherein the first carbon material precursor comprises at least one of a polymer precursor, a biomass precursor, and a fossil carbon source.

[0029] Furthermore, a heteroatom-containing precursor is introduced when the silicon-containing precursor is contacted with the C / C composite porous material in step S2. Preferably, the contacting method of the silicon-containing precursor and the heteroatom-containing precursor with the C / C composite porous material includes: (1) alternately contacting the silicon-containing precursor and the heteroatom-containing precursor with the C / C composite porous material; (2) simultaneously contacting the silicon-containing precursor and the heteroatom-containing precursor with the C / C composite porous material; or (3) alternately contacting the silicon-containing precursor, the silicon-containing precursor, and the heteroatom-containing precursor with the C / C composite porous material; or continuously contacting the silicon-containing precursor with the C / C composite porous material and intermittently contacting the heteroatom-containing precursor with the C / C composite porous material. The contacting temperature of the silicon-containing precursor and the heteroatom-containing precursor with the C / C composite porous material is 150°C to 1000°C, and the contacting time is 1 to 100 hours.

[0030] Furthermore, the silicon-containing precursor includes at least one of monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, and silafluorene and its derivatives.

[0031] Additionally, the heteroatom-containing precursor includes at least one of a nitrogen-containing precursor, a phosphorus-containing precursor, a sulfur-containing precursor, and a boron-containing precursor.

[0032] A third aspect of the present disclosure provides a negative electrode comprising the silicon carbon composite material according to the first aspect or the silicon carbon composite material obtained by the manufacturing method according to the second aspect.

[0033] A fourth aspect of the present disclosure provides a battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the negative electrode comprises the silicon carbon composite material according to the first aspect or the silicon carbon composite material obtained by the manufacturing method according to the second aspect.

[0034] The present disclosure has at least the following beneficial effects compared to the prior art:

[0035] The silicon-carbon composite material provided by the present disclosure is fabricated by introducing a second carbon material into a C / C composite porous material, forming a conductive network structure with strength and toughness between the porous carbon substrate and silicon nanoparticles. This prevents separation of the silicon and the porous carbon substrate during volume changes and improves the electronic and ionic conductivity of the silicon-carbon composite. The second carbon material increases strength and toughness, forming a flexible network structure that constrains silicon expansion. Furthermore, structural stability can be ensured at low SOCs, improving the cycle and structural stability of the silicon-carbon composite.

[0036] In the method for producing a silicon-carbon composite material provided by the present disclosure, the first carbon precursor loses small organic molecules and releases small molecules such as CO2 and HO during the sintering, pore-forming, and activation processes, forming a porous carbon substrate. Meanwhile, the second carbon precursor becomes weightless during the sintering and pore-forming processes, barely forming pores, and retains its dimensions and structure. This allows the second carbon material to form a composite structure that permeates the C / C porous composite material. Furthermore, after silicon is deposited in the pores of the C / C porous composite material, the second carbon material can also form a composite structure that permeates the silicon-carbon composite material. The resulting silicon-carbon composite material has the same beneficial effects as the silicon-carbon composite material described above. [Brief explanation of the drawings]

[0037] In order to more clearly explain the technical solutions of the embodiments of the present application, the following will briefly explain the drawings necessary for describing the embodiments. The following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope. It should be understood that those skilled in the art can obtain other related drawings based on these drawings without using inventive ability.

[0038] [Figure 1] 1 is an SEM image of the silicon carbon composite material obtained in Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0039] Hereinafter, embodiments of the present disclosure will be described in detail using examples. The following examples are merely for the purpose of illustrating the present disclosure and should not be considered as limiting the scope of the present disclosure. In the examples, specific conditions are not specified, but the experiments can be carried out under conventional conditions or under conditions recommended by the manufacturer. For reagents or equipment used without specifying the manufacturer, conventional commercially available products can be used.

[0040] The range endpoints and any values ​​disclosed in this disclosure should be understood not to be limited to the exact range or value, but to include values ​​close to these ranges or values. For numerical ranges, the range endpoints, the range endpoints and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0041] A first aspect of the present disclosure provides a silicon-carbon composite material comprising silicon-carbon composite particles, the silicon-carbon composite particles comprising a porous C / C composite material and silicon nanoparticles located within the pores and on the surface of the porous C / C composite material. The porous C / C composite material comprises a first carbon material and a second carbon material, the first carbon material being a porous carbon substrate, the second carbon material perforating the interior of the porous C / C composite material and further perforating the silicon-carbon composite material, and at least one dimension of the second carbon material being greater than 100 nm.

[0042] The silicon carbon composite material provided by this disclosure is a C / C composite porous material prepared by introducing a second carbon material. This creates a conductive network structure with strength and toughness between the porous carbon substrate and silicon nanoparticles, preventing separation of the silicon and the porous carbon substrate during volumetric changes and improving the electronic and ionic conductivity of the silicon carbon composite. The second carbon material increases strength and toughness, forming a flexible constraining network structure that prevents silicon expansion. Furthermore, structural stability can be ensured at low SOCs, improving the cycle stability and structural stability of the silicon carbon composite.

[0043] The functions of the second carbon material in silicon-carbon composite particles are as follows: (1) When the SOC is low, the second carbon material forms conductive whiskers in the composite. These conductive whiskers connect the silicon nanoparticles and the porous carbon substrate, forming conductive paths. This prevents the risk of separation between the silicon nanoparticles and the porous carbon substrate due to shrinkage of the silicon nanoparticles under low load, further improving conductivity and reducing the resistance (DCIR) of batteries containing the composite. (2) It forms a transmission path, improving the power multiplication performance. (3) The second carbon material combines with the first carbon material to form an elastic mesh, improving the pressure resistance of the material.

[0044] In some embodiments, the proportion of the second carbon material in the C / C composite porous material is 0.01 to 10 wt.%. The second carbon material includes at least one of carbon nanotubes, graphene, carbon black, and carbon fibers. When the proportion of the second carbon material in the C / C composite porous material is greater than 10 wt.%, it affects the uniformity of the pore distribution of the C / C composite porous material and further affects the uniformity of the silicon nanoparticles of the silicon-carbon composite material, leading to a decrease in material performance. Also, since the cost of the second carbon material is high, using a large amount will increase the cost. Typically, the proportion of the second carbon material in the C / C composite porous material is 0.01%, 0.1 wt.%, 0.5 wt.%, 1 wt.%, 3 wt.%, 5 wt.%, 7 wt.%, 9 wt.%, 10 wt.% or a range consisting of any two of the above values, but is not limited thereto.

[0045] Furthermore, the dimension of the second carbon material in the first dimension is L, satisfying 100 nm < L < 100 μm, and the dimension of the second carbon material in the second dimension is a, satisfying 0 < a < 20 nm. Further, L satisfies 100 nm < L < 20 μm, and a satisfies 0 < a < 10 nm. The second carbon material has a dimension of L in the first dimension direction and a dimension of a in the second dimension direction in three-dimensional space. In some specific embodiments, when the second carbon material is, for example, a carbon nanotube (CNT), L is the length and a is the diameter. Further, for example, when it is graphene, L is the length or width of the graphene plane, and a is the thickness of the sheet. The smaller the dimension a of the second carbon material in the second dimension, the higher the flexibility and strength. Therefore, the formed C / C composite material has higher stability, and the silicon-carbon composite material has higher stability, so the expansion restraint force against silicon is stronger.

[0046] In some embodiments, the ratio of the compressed specific surface area of ​​the silicon carbon composite to the specific surface area of ​​the silicon carbon composite (compressed specific surface area / specific surface area) is small because the material has high mechanical strength and structural stability and is not easily damaged by high pressure. 2 The specific surface area of ​​the silicon carbon composite material after consolidation at a pressure of 4000 kgf / cm is the specific surface area of ​​the material after consolidation at a pressure of 4000 kgf / cm. 2 The specific surface area of ​​the material after compaction under this pressure is 1 to 20 times, preferably 1 to 10 times, and more preferably 1 to 5 times the specific surface area of ​​the silicon carbon composite material.

[0047] In some embodiments, the pore volume of the C / C composite porous material is 0.2 to 3.0 cm 3 / g, and the volume ratio of micropores is greater than 50%. Preferably, in some embodiments, the pore volume of the C / C composite porous material is 0.4 to 1.5 cm 3 / g, and the volume ratio of micropores is greater than 70%.

[0048] In some embodiments, the silicon nanoparticles have a diameter of 0.5 to 5 nm. Preferably, in some embodiments, the silicon content in the silicon carbon composite is 5 to 80 wt.% (e.g., 5 wt.%, 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, or a range consisting of any two of the above values).

[0049] In some embodiments, the silicon carbon composite particles further comprise heteroatoms X located within the pores of the C / C composite porous material, the heteroatoms X comprising at least one of B, N, P, O, and S. The heteroatoms X form Si-X chemical bonds with silicon atoms in the silicon nanoparticles, isolating and encapsulating the silicon nanoparticles. Preferably, in some embodiments, the content of the heteroatoms in the silicon carbon composite is 0-10 wt.%.

[0050] In some embodiments, the surface of the silicon carbon composite particle has a coating layer, and the material of the surface coating layer is preferably one or more selected from the group consisting of solid electrolytes, conductive polymers, carbonaceous materials, metals, alloys, metal oxides, metal halides, metal sulfides, metal phosphates, borates, sulfates, nitrates, and polyoxometalates.

[0051] More preferably, in some embodiments, the carbonaceous material includes, but is not limited to, carbon nanotubes, graphene, carbon black, or carbon fibers. In some embodiments, the organic polymer includes, but is not limited to, polyoxyethylene, polyethylene glycol, phenolic resin, epoxy resin, or polysaccharide.

[0052] In some embodiments, the coating layer may include, but is not limited to, one or more of lithium hydroxide, lithium carbonate, lithium fluoride, lithium phosphate, lithium metaphosphate, aluminum dihydrogen phosphate, lithium metaaluminate, lithium aluminum phosphate, aluminum phosphate, aluminum metaphosphate, alumina, alumina monohydrate, alumina trihydrate, aluminum hydroxide, alumina sol, aluminum isopropoxide, magnesium oxide, magnesium hydroxide, zinc oxide, zinc hydroxide, titanium oxide, zirconium oxide, LiPON (lithium oxynitride phosphate), LLZO (lithium lanthanum zirconium oxygen), LATP (lithium aluminum titanium phosphate), LLTO (lithium lanthanum titanate), and lithium germanium phosphorus sulfur compounds. In some embodiments, the coating layer may include, but is not limited to, one or more of polymers, such as polyoxyethylene, carboxymethyl cellulose, polyacrylic acid, or polyacrylonitrile, and lithium complexes thereof. In some embodiments, the coating layer includes, but is not limited to, one or more of a LISICON-type solid electrolyte, a NASICION-type solid electrolyte, a perovskite-type solid electrolyte, a garnet-type solid electrolyte, and a sulfide solid electrolyte. In some embodiments, the coating layer includes, but is not limited to, one or more of a metal phosphate, a borate, a sulfate, a nitrate, a polyoxometalate, and the like.

[0053] In some embodiments, the surface of the silicon-carbon composite particles has a lattice-structured coating layer. Preferably, the coating layer is made of at least one of carbon nanotubes, graphene, carbon black, and carbon fiber. The carbon material forms a lattice-structured coating layer on the surface of the composite material, thereby suppressing the volume expansion of the silicon nanoparticles within the material. The lattice-structured coating layer formed by the carbon material forms a conductive path, significantly reducing the electrical resistivity of the composite material. This stabilizes the interface, stabilizes the SEI film, and reduces lithium ion consumption.

[0054] In some embodiments, the specific surface area of ​​the silicon carbon composite material is 0.1 to 50 m 2 / g, and the pore volume is 0.01 to 0.5 cm 3 In some embodiments, the specific surface area of ​​the silicon carbon composite material is preferably 0.1 to 10 m / g. 2 / g, and the pore volume is 0.01 to 0.1 cm 3 / g.

[0055] In some embodiments, the silicon carbon composite has a true density of 1.3 to 2.0 g / cm 3 The closed pore volume is 0.01 to 0.25 cm 3 / g.

[0056] A second aspect of the present disclosure provides a method for producing a silicon-carbon composite material. Step S1: Provide a C / C composite porous material containing a first carbon material and a second carbon material, where the first carbon material is a porous carbon substrate and the second carbon material perforates the interior of the C / C composite porous material and further perforates the silicon-carbon composite material. Step S2: Contact a silicon-containing precursor with the C / C composite porous material and perform chemical vapor deposition to distribute silicon nanoparticles within the pores and on the surface of the C / C composite porous material, thereby obtaining the silicon-carbon composite material. The C / C composite porous material, the first carbon material, the second carbon material, and the silicon nanoparticles have the same meanings as in the first aspect.

[0057] In the method for producing a silicon-carbon composite material provided by the present disclosure, the first carbon precursor loses small organic molecules and releases small molecules such as CO2 and HO during the sintering, pore-forming, and activation processes, forming a porous carbon substrate. Meanwhile, the second carbon precursor becomes weightless during the sintering and pore-forming processes, barely forming pores, and retains its dimensions and structure. This allows the second carbon material to form a composite structure that permeates the C / C porous composite material. Furthermore, after silicon is deposited in the pores of the C / C porous composite material, the second carbon material can also form a composite structure that permeates the silicon-carbon composite material. The resulting silicon-carbon composite material has the same beneficial effects as the silicon-carbon composite material described above.

[0058] In some embodiments, the method for producing a C / C composite porous material includes introducing a second carbon material in at least one of different manufacturing steps in the production of a porous carbon material, such as a carbon precursor step, a carbon precursor pre-stabilization step, a carbonization step, a further pore-forming step, and a finished carbon material step.

[0059] Preferably, in some embodiments, the first carbon material precursor and the second carbon material are mixed, and the mixture is sintered in an inert atmosphere or a mixed atmosphere of an inert gas and an oxygen-containing gas to obtain a C / C composite porous material.

[0060] In some other embodiments, the method for producing the C / C composite porous material includes sintering a first carbon material precursor in an inert atmosphere to obtain the first carbon material, mixing the first carbon material with a second carbon material, and sintering the mixture to obtain the C / C composite porous material.

[0061] In some embodiments, a pore-forming agent may be added to the first carbon precursor during the preparation of the C / C composite porous material to form a porous carbon substrate with a large pore structure after sintering. The pore-forming agent may be one or more selected from the group consisting of sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, oleic acid, oleylamine, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymers (e.g., P123, F127, and / or F108), citric acid, malic acid, succinic acid, NH4HCO3, (NH4)2CO3, HNO3, H2SO4, LiOH, NaOH, and KOH.

[0062] In some embodiments, the first carbonaceous material precursor comprises at least one of a polymer precursor, a biomass precursor, and a fossil carbon source. For example, the first carbonaceous material precursor may be, but is not limited to, one or more of glucose, sucrose, maltose, lactose, cyclodextrin, starch, glycogen, cellulose, hemicellulose, lignin, epoxy resin, thermoplastic phenolic resin, thermosetting phenolic resin, polyformaldehyde resin, urea resin, furfural resin, furfural acetone resin, acrylic resin, coconut shell, rice husk, and wood.

[0063] In some embodiments, the step of preparing the C / C composite porous material further includes activating the resulting C / C composite porous material to form pores. Specifically, the C / C composite porous material is contacted with an oxygen-containing substance. Examples of the oxygen-containing substance include, but are not limited to, gases such as H2O, CO2, and O2; solids such as KOH, NaOH, K2CO3, Na2CO3, potassium acetate, and sodium acetate, and their aqueous solutions; and H3PO4 or its aqueous solution. The contacting method can be gas-solid contact, solid-solid contact, or solid-liquid contact. The contacting temperature is 300 to 1200°C (e.g., 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, or any temperature between these), preferably 600 to 900°C.

[0064] In some embodiments, the contact temperature between the silicon-containing precursor and the C / C composite porous material in step S2 is 150° C. to 1000° C., and the contact time is 1 to 100 hours.

[0065] In some embodiments, a heteroatom-containing precursor is introduced when contacting the silicon-containing precursor with the C / C composite porous material in step S2. Preferably, the method for contacting the silicon-containing precursor and the heteroatom-containing precursor with the C / C composite porous material includes: (1) contacting the silicon-containing precursor and the heteroatom-containing precursor alternately with the C / C composite porous material; (2) contacting the silicon-containing precursor and the heteroatom-containing precursor simultaneously with the C / C composite porous material; or (3) contacting the silicon-containing precursor, the silicon-containing precursor, and the heteroatom-containing precursor alternately with the C / C composite porous material; or continuously contacting the silicon-containing precursor with the C / C composite porous material and intermittently contacting the heteroatom-containing precursor with the C / C composite porous material.

[0066] Furthermore, the temperature for contacting the silicon-containing precursor and heteroatom-containing precursor with the C / C composite porous material is 150°C to 1000°C (e.g., 150°C, 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, or 1000°C, or any temperature between these two temperatures), and the time is 1 to 100 hours (e.g., 1 hour, 12 hours, 24 hours, 36 hours, 48 ​​hours, 72 hours, 96 hours, or 100 hours, or any time between these two temperatures).

[0067] In some embodiments, the silicon-containing precursor comprises at least one of monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, and silafluorene and its derivatives.

[0068] In some embodiments, the heteroatom-containing precursor includes, but is not limited to, any one or a mixture of two or more of a boron-containing precursor, a nitrogen-containing precursor, a phosphorus-containing precursor, an oxygen-containing precursor, and a sulfur-containing precursor, where the boron-containing precursor includes B(CH3)3, the nitrogen-containing precursor includes NH3, NO, NO, and acetonitrile, and the phosphorus-containing precursor includes PH3 and POCl3, the oxygen-containing precursor includes oxygen, carbon dioxide, water vapor, methanol, ethanol, n-propanol, isopropanol, butanol, acetone, and butanone, and the sulfur-containing precursor includes, but is not limited to, any one or a mixture of two or more of H2S and SO2.

[0069] A third aspect of the present disclosure provides a negative electrode comprising the silicon carbon composite material according to the first aspect or the silicon carbon composite material obtained by the production method according to the second aspect.

[0070] A fourth aspect of the present disclosure provides a battery including a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the negative electrode comprises the silicon carbon composite material according to the first aspect or a silicon carbon composite material obtained by the manufacturing method according to the second aspect. By employing the silicon carbon composite material, the energy density of the battery can be effectively increased, the internal resistance can be reduced, and the range of application can be expanded.

[0071] The present disclosure will be further described below using specific examples and comparative examples. However, it should be understood that these examples are intended to explain the present disclosure in more detail and are not intended to limit the disclosure in any way. The materials used in the examples and comparative examples in this disclosure can be processed under conventional conditions or under conditions recommended by the manufacturer, unless specific conditions are specified. For reagents or equipment used without a specified manufacturer, commercially available conventional products can be used.

[0072] Example 1

[0073] This example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0074] (1) Sucrose and single-walled carbon nanotubes (Dazhan Nano (Guangdong) Co., Ltd., outer diameter range 1.6±0.4 nm, length ≥ 5 μm) were mixed at a mass ratio of 100 / 0.01. The resulting mixture was heated from room temperature to 800°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours. The resulting material was crushed and classified, then mixed with KOH in a ratio of m(KOH):m(C) = 1:2, and activated at 800°C for 2 hours to obtain a C / C composite porous material. The proportion of carbon nanotubes in the porous composite skeleton was 0.1 wt.%, and the pore volume of the C / C composite porous material was 0.80 cm. 3 / g, and the ratio of the volume of micropores to the total pore volume is 85%.

[0075] (2) The C / C composite porous material was placed in a tubular furnace and heated from room temperature to 600°C at a rate of 2°C / min in an N2 atmosphere. The atmosphere was then changed to a 20% SiH4-N2 mixed gas and maintained at 600°C for 30 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was allowed to drop naturally, and the material was crushed and classified to obtain a silicon-carbon composite material. The silicon content of the silicon-carbon composite material was 52 wt.%.

[0076] Example 2

[0077] This example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0078] (1) The difference from the corresponding step in Example 1 is that the proportion of single-walled carbon nanotubes in the C / C composite porous material is 0.01 wt.%. The other raw materials and methods are the same as the corresponding steps in Example 1, so the explanation is omitted here.

[0079] (2) Same as in Example 1.

[0080] Example 3

[0081] This example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0082] (1) The difference from the corresponding step in Example 1 is that the proportion of single-walled carbon nanotubes in the C / C composite porous material is 0.5 wt.%. The other raw materials and methods are the same as the corresponding steps in Example 1, so the explanation is omitted here.

[0083] (2) Same as in Example 1.

[0084] Example 4

[0085] This example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0086] (1) The difference from the corresponding steps in Example 1 is that graphene (Toray Advanced Materials (Guangdong) Co., Ltd., sheet thickness <15 nm, graphene plane length or width 3-6 μm) is used instead of single-walled carbon nanotubes, and the proportion of graphene in the porous composite skeleton is 2 wt.%. The other raw materials and methods are the same as the corresponding steps in Example 1, and their explanations are omitted here.

[0087] (2) Same as in Example 1.

[0088] Example 5

[0089] This example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0090] (1) Same as Example 1.

[0091] (2) The C / C composite porous material was placed in a tubular furnace and heated from room temperature to 600°C at a rate of 2°C / min in an N2 atmosphere. The atmosphere was then changed to a 20% SiH4-0.002% CO2-N2 mixed gas, and the material was maintained at 600°C for 30 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the material was allowed to cool naturally, crushed, and classified to obtain a silicon-carbon composite material.

[0092] Example 6

[0093] This example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0094] (1) Same as Example 1.

[0095] (2) Same as in Example 1.

[0096] (3) The silicon-carbon composite particles were uniformly dispersed in pure water, and 0.4% by mass of CNTs (same manufacturer and model number as the single-walled carbon nanotubes in Example 1) was added. The mixture was stirred uniformly and then spray-dried to obtain a silicon-carbon composite coated with CNTs.

[0097] Example 7

[0098] This example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0099] (1) Same as Example 1.

[0100] (2) Same as in Example 1.

[0101] (3) The silicon-carbon composite particles were uniformly dispersed in pure water, and 1% by mass of CNTs (same manufacturer and model number as the single-walled carbon nanotubes in Example 1) and 3% by mass of lithium phosphate were added. The mixture was stirred uniformly, filtered, and dried to obtain a silicon-carbon composite coated with a composite fast ion conductor coating layer. The mass ratio of CNTs to lithium phosphate was 0.3:1, and the coating layer thickness was 6 nm.

[0102] Example 8

[0103] This example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0104] (1) The difference from the corresponding steps in Example 1 is that multi-walled carbon nanotubes (Zhongke Leiming (Beijing) Technology Co., Ltd., outer diameter 30-60 nm, inner diameter 20-50 nm, length 1-10 μm) are used instead of single-walled carbon nanotubes, and the proportion of carbon nanotubes in the porous composite skeleton is 10 wt.%. The other raw materials and methods are the same as the corresponding steps in Example 1, and their explanation is omitted here.

[0105] (2) Same as in Example 1.

[0106] Example 9

[0107] This example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0108] (1) The difference from the corresponding steps in Example 1 is that multi-walled carbon nanotubes (Shenzhen Tuling New Materials Co., Ltd., diameter 3-15 nm, length 15-30 μm) are used instead of single-walled carbon nanotubes, and the proportion of carbon nanotubes in the porous composite skeleton is 5 wt.%. The other raw materials and methods are the same as the corresponding steps in Example 1, and their explanation is omitted here.

[0109] (2) Same as in Example 1.

[0110] Example 10

[0111] (1) Sucrose and single-walled carbon nanotubes (Dazhan Nano (Guangdong) Co., Ltd., outer diameter range 1.6±0.4 nm, length ≥ 5 μm) were mixed in a mass ratio of 100 / 0.01. The resulting mixture was heated from room temperature to 800°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours. The resulting material was crushed and classified, then mixed with KOH in a ratio of m(KOH):m(C) = 1:2, and activated at 800°C for 0.5 hours to obtain a C / C composite porous material. The proportion of carbon nanotubes in the porous composite skeleton was 0.15 wt.%, and the pore volume of the C / C composite porous material was 0.40 cm. 3 / g, and the ratio of the volume of micropores to the total pore volume is 88%.

[0112] (2) The C / C composite porous material was placed in a tubular furnace and heated from room temperature to 600°C at a rate of 2°C / min in an N2 atmosphere. The atmosphere was then changed to a 10% SiH4-N2 mixed gas and held at 600°C for 10 hours in a 10% SiH4-N2 mixed gas atmosphere. After changing to the N2 atmosphere, the temperature was allowed to naturally decrease, and once it reached room temperature, dry air was introduced. After 2 hours, the temperature was slowly increased to 200°C and held in an air atmosphere for 2 hours. The temperature was then increased to 600°C in an N2 atmosphere, changed to a 10% C2H2-N2 atmosphere, and held for 2 hours. The resulting material was crushed and classified to obtain a silicon-carbon composite. The silicon content of the resulting silicon-carbon composite was 8 wt.%.

[0113] Example 11

[0114] (1) Sucrose and single-walled carbon nanotubes (Dazhan Nano (Guangdong) Co., Ltd., outer diameter range 1.6±0.4 nm, length ≥ 5 μm) were mixed in a mass ratio of 100 / 0.01. The resulting mixture was heated from room temperature to 800°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours. The resulting material was crushed and classified, then mixed with KOH in a ratio of m(KOH):m(C) = 1:2, and activated at 800°C for 5 hours to obtain a C / C composite porous material. The carbon nanotubes accounted for 0.06 wt.% of the porous composite skeleton, and the pore volume of the C / C composite porous material was 1.50 cm3. 3 / g, and the ratio of the volume of micropores to the total pore volume is 86%.

[0115] (2) The difference from the corresponding steps in Example 1 is that the volume content of SiH4 in the SiH4-N2 mixed gas was changed to 30%, and the deposition time was changed to 40 hours. The other raw materials and methods were the same as the corresponding steps in Example 1, and their explanations are omitted here. The silicon content of the obtained silicon carbon composite material was 78 wt.%.

[0116] Comparative Example 1

[0117] This comparative example provides a silicon carbon composite material, and the manufacturing method is as follows.

[0118] (1) Sucrose was heated from room temperature to 800°C at a rate of 2°C / min in a N2 atmosphere and held at this temperature for 2 hours. The resulting material was crushed and classified, then mixed with KOH in a ratio of m(KOH):m(C) = 1:2, and activated at 800°C for 2 hours to obtain porous carbon.

[0119] (2) The porous carbon was placed in a tubular furnace and heated in an N2 atmosphere at a rate of 2°C / min from room temperature to 600°C. The atmosphere was then changed to a 20% SiH4-N2 mixed gas and maintained at 600°C for 30 hours in a 20% SiH4-N2 mixed gas atmosphere. After changing to an N2 atmosphere, the temperature was allowed to drop naturally, and the material was crushed and classified to obtain a silicon carbon composite material.

[0120] Measurement example 1

[0121] The physicochemical parameters of the silicon carbon composite materials obtained in Examples 1 to 9 and Comparative Example 1 were measured.

[0122] The specific surface area of ​​the particles was measured using a specific surface area analyzer.

[0123] The true density of the particles was measured using a fully automatic true density measuring device.

[0124] Compacted specific surface area: 4000 kgf / cm when powder is placed in a 12 mm diameter mold2 A pressure of 1000 kJ / cm2 is applied and held for 30 seconds, and the specific surface area of ​​the material after compaction is measured and expressed as the compacted specific surface area. The smaller the ratio of the compacted specific surface area to the specific surface area, the stronger the pressure resistance of the material.

[0125] The data obtained is shown in Table 1.

[0126] [Table 1]

[0127] As can be seen from Table 1, Examples 1 to 11 have a lower ratio of consolidated specific surface area to specific surface area compared to the Comparative Examples. Therefore, the silicon-carbon composite material obtained by performing chemical vapor deposition of silicon on a C / C composite material with the addition of a second carbon material as the substrate has higher compressive strength, and the electrodes manufactured from the materials in the Examples have higher cycle stability. Among them, the improvement in the compressive strength of the materials with single-walled carbon nanotubes and graphene having smaller dimensions in the second dimension is more significant. For example, the ratio of the consolidated specific surface area to the specific surface area in Examples 1 to 6 is smaller than that in Examples 8 and 9, and their electrochemical performance is slightly inferior. In Example 5, compared with Example 1, further CO2 passivation treatment was performed. Due to its weak oxidizing property, some of the silicon nanoparticles were encapsulated by oxygen-containing substances such as SiOx substances (0 < x < 1), so the composite material showed higher compressive strength. In Example 6, compared with Example 1, further CNT coating was performed, further improving the compressive strength of the composite material. In Example 7, compared with Example 1, lithium phosphate coating was added, that is, composite coating of CNT and lithium phosphate was added. In Examples 8 and 9, instead of single-walled CNTs, multi-walled carbon nanotubes with a large diameter were used for coating. The tube diameter of the carbon nanotubes is relatively thick, and the flexibility is greatly reduced. A high addition amount is required to form a suitable conductive network structure in the composite material. Therefore, the consolidated density of the material decreases, and further affects its electrochemical stability. Examples 10 and 11 are examples in the cases of low silicon content and high silicon content, respectively. When the silicon content is low, the pore volume of the desired C / C composite porous material substrate is small. Therefore, in the C / C composite porous material obtained by adding CNTs with the same proportion of addition amount to the precursor, the CNT content is relatively large. As a result, the CNT content in the final silicon-carbon composite material is also relatively large. Thus, this material has the minimum consolidated specific surface area, that is, the highest compressive strength of this composite material. The porous carbon matrix of Comparative Example 1 does not contain a second carbon material, and the specific surface area of the obtained silicon-carbon composite material after consolidation at a pressure of 4000 kgf / cm 2 is 92 m 2 / g. As can be seen, the compressive strength of this composite was very low, which significantly affected the cycle stability in lithium-ion batteries.

[0128] Measurement example 2

[0129] The silicon-carbon composite material obtained in Example 6 was observed using a field-emission scanning electron microscope, and the resulting SEM photograph is shown in Figure 1. As can be seen from Figure 1, the CNTs coated the outside of the particles, forming an intertwined conductive network structure. In the SEM images of Examples 1 to 5, it is difficult to directly observe the presence of the second carbon material. This is because the second carbon material, such as CNT or graphene, has a diameter or thickness dimension of 10 nm or less or 3 nm or less, and is tightly connected to the first carbon material within the C / C porous composite material. It is usually located inside the composite, making it difficult to observe the second carbon material on the surface of the composite.

[0130] Measurement example 3

[0131] The silicon carbon composite materials obtained in Examples 1 to 9 and Comparative Example 1 were measured for powder electrical resistivity under a pressure of 20 MPa using a four-probe powder electrical resistivity measuring device, Model ST 2722-SZ, manufactured by Suzhou Crystal Electronics Co., Ltd. The obtained data are shown in Table 2.

[0132] Measurement example 4

[0133] The silicon carbon composite materials obtained in Examples 1 to 9 and Comparative Example 1 were used as negative electrode active materials to prepare negative electrode sheets, and CR 2032 button batteries were manufactured using a conventional method, and the electrical performance of the batteries was measured.

[0134] The specific measurement method is as follows.

[0135] (1) Half-cell assembly

[0136] A CR 2032 button battery was assembled in a glove box, with a metallic lithium sheet as the counter electrode and a polypropylene microporous membrane as the separator. The electrolyte consisted of LiPF6 dissolved in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio EC:DEC = 1:1), where the concentration of LiPF6 was 1 mol / L.

[0137] Battery charge and discharge measurements were performed using the LAND battery measurement system.

[0138] (2) Capacity per gram and initial efficiency measurements

[0139] After leaving the CR 2032 button cell for 6 hours, it was discharged at 0.05 C to 0.005 V, then further discharged at 0.01 C to 0.005 V, left for 5 minutes, and then charged at a constant current of 0.05 C to 1.5 V. The capacity per gram of initial lithium desorption is the capacity per gram (or gravimetric capacity) of the electrode material.

[0140] The data obtained is shown in Table 2.

[0141] Measurement example 5

[0142] The silicon carbon composite materials obtained in Examples 1 to 9 and Comparative Example 1 were used as negative electrode active materials, and pouch batteries were fabricated using electrode pieces containing the negative electrode active materials in a conventional manner, and electrical performance measurements were performed. The pouch batteries were fabricated in a dehumidified room with a dew point temperature of -45°C. The charge / discharge cycles of the batteries were measured using a LANBTS battery measurement system, and the specific measurement method is as follows.

[0143] (1) Preparation of the positive electrode sheet

[0144] The positive electrode active material NCM811, the conductive agent SuperP, the adhesive PVDF, and the solvent NMP were mixed uniformly in a mass ratio of 92:3:5:150 by stirring, and then the mixture was uniformly applied to the positive electrode current collector and dried at 80°C to obtain a positive electrode sheet.

[0145] (2) Preparation of negative electrode sheet

[0146] The silicon carbon composite materials obtained in Examples 1 to 9 and Comparative Example 1 were mixed with graphite to obtain negative electrode active materials. The negative electrode active materials, conductive agent SuperP, adhesive (i.e., polyacrylic acid), and solvent (i.e., deionized water) were uniformly mixed by stirring in a mass ratio of 95:1:4:120, and then the mixture was uniformly applied to a negative electrode current collector and dried at 100°C to obtain a negative electrode sheet.

[0147] (3) The positive and negative electrode sheets were stacked in a rectangular shape and separated using a polypropylene separator to form a battery cell, which was then enclosed in an aluminum plastic bag. An electrolyte solution appropriate for the capacity of the bag was then injected into the bag, which was then vacuum sealed to form a pouch battery. The electrolyte solution was a mixture of LiPF6, EC, and DEC, where the LiPF6 concentration was 1 mol / L and the volume ratio of EC to DEC was 1:1.

[0148] (4) Chemical composition and volume classification (volume classification, performance screening and grading)

[0149] The filled and sealed batteries were then subjected to anodization. After standing for 12 hours in a 25°C thermostat, they were charged to 3.3 V at a constant current of 0.02 C, left for 30 minutes, charged to 3.8 V at a constant current of 0.025 C, left for 10 minutes, and then charged to 4.2 V at a constant current of 0.33 C. After anodization, the batteries were evacuated, the sealing bag was sheared, and the batteries were then divided. They were charged to 4.45 V at a constant current of 0.33 C, left for 10 minutes, discharged to 3 V at a constant current of 1 C, left for 10 minutes, and then discharged to 3 V at a constant current of 0.33 C. The initial coulombic efficiency of the pouch battery was determined by dividing the discharge capacity by the charge capacity.

[0150] (5) Cycle measurement at 25°C

[0151] The battery was placed in a thermostatic chamber at 25°C and charged at a constant current of 1 C to 4.45 V, then further charged at a constant voltage of 4.45 V until the current reached 0.1 C. After allowing the battery to stand for 10 minutes, it was discharged at a constant current of 1 C to 3.0 V, allowed to stand for 10 minutes, and the above charge and discharge process was repeated until the discharge capacity was less than 80% of the first-cycle discharge capacity. The resulting number of cycles was the cycle life of the pouch battery. The capacity retention at 100 cycles was recorded.

[0152] (6) Magnification performance measurement

[0153] The manufactured button-type batteries were left to stand at room temperature for 12 hours, and then subjected to constant current charge / discharge measurements using a LAND measurement system. The charge / discharge cutoff voltage was 3.0 to 4.25 V. First, the batteries were charged / discharged at a current of 0.25 C, and cycled three times. Then, the batteries were charged / discharged at a current of 0.5 C, and cycled three times. Finally, the batteries were charged / discharged at a current of 1 C, and cycled three times. The capacity retention rate was calculated by dividing the discharge capacity at the 9th cycle by the discharge capacity at the 1st cycle x 100%, and the higher the value, the better the performance.

[0154] (7) DCIR measurement

[0155] The formed and divided batteries were placed in a thermostatic chamber at 25°C and charged at a constant current of 1C to 4.45V. The charge capacity was recorded as Q1. After 10 minutes of rest, the batteries were discharged at a constant current of 1C to 3.0V and then rested for 10 minutes. Charging continued at a constant current of 1C until a capacity of Q2 (Q2 = Q1 * 10%) was reached, i.e., the battery capacity reached 10% SOC. After 10 minutes of rest, the battery voltage at this time was recorded as U0. The battery was then discharged at a constant current of 5C for 18 seconds. The battery voltage at this time was recorded as U1. The discharge DC internal resistance of this battery at 10% SOC, DCIR, was calculated as (U0 - U1) / 5C.

[0156] The data obtained is shown in Table 2.

[0157] [Table 2]

[0158] As can be seen from Table 2, the difference in silicon content between the silicon carbon composites obtained in Examples 1-11 and Comparative Example 1 is not significant, and therefore the capacity per gram is not significantly different. Compared to Comparative Example 1, the introduction of a second carbon material in Examples 1-11 established a conductive network structure within the C / C composite porous material. This resulted in significantly lower electrical resistivity and DCIR than Comparative Example 1, improved ionic conductivity, and significantly higher multiplication performance than Comparative Example 1. The silicon carbon composites obtained in Examples 6 and 7 each had a CNT coating layer and a composite coating layer of CNT and lithium phosphate, respectively, resulting in significantly better electrical resistivity, multiplication performance, and DCIR. The second carbon material possessed good flexibility, which increased the strength of the silicon carbon composite, enhanced the structural stability of the material, and further improved cycling stability. Therefore, the initial coulombic efficiency and 100-cycle capacity retention of the silicon carbon composites obtained in Examples 1-11 were both higher than Comparative Example 1.

[0159] Compared to Examples 8 and 9, Examples 1 to 3 use single-walled carbon nanotubes as the second carbon material. Because single-walled carbon nanotubes have a higher Young's modulus than multi-walled carbon nanotubes, a smaller diameter, better flexibility, and higher strength, the resulting C / C porous composite materials, and even the silicon-carbon composite materials, are more stable. Therefore, the cycle stability of the composites of Examples 1 to 3 is superior to that of Examples 8 and 9. In Example 8, the multi-walled carbon nanotubes have a relatively large diameter, significantly reducing flexibility. A relatively high addition amount is required to form an appropriate conductive network structure in the composite, which results in the formation of many closed pores in the composite, reducing the compaction density of the material and reducing structural stability during cycling.

[0160] In Example 5, compared to Example 1, the doping element O was introduced to separate and encapsulate the silicon nanoparticles, improving the electrical conductivity and ionic conductivity of the silicon region, and the magnification performance was higher than that of Example 1.

[0161] Examples 10 and 11 are examples with low and high silicon contents, respectively. The composite material of Example 10 has a low silicon content, resulting in a low specific capacitance. However, due to the relatively high CNT content, its fold-to-weight ratio, electrical resistivity, and DCIR are all very low, resulting in excellent cycle stability. Example 11 has a high silicon content, resulting in a high specific capacitance, but its cycle stability is relatively poor compared to Example 10.

[0162] Finally, it should be noted that the above embodiments are merely for illustrating the technical solutions of the present invention, and are not intended to limit the same. Although the above embodiments are used to describe the present invention in detail, those skilled in the art may modify the technical solutions described in the above embodiments or make equivalent substitutions for some or all of the technical features therein. Such modifications or substitutions do not deviate from the essence of the technical solutions and the scope of the technical solutions according to the embodiments of the present invention. [Industrial Applicability]

[0163] The method disclosed herein is advantageous in improving the cycle stability and structural stability of silicon carbon composite materials, and in realizing the industrialization of silicon carbon composite materials.

Claims

1. A silicon carbon composite material, comprising: silicon carbon composite particles, the silicon carbon composite particles include a C / C composite porous material and silicon nanoparticles located within the pores and on the surface of the C / C composite porous material; The C / C composite porous material includes a first carbon material and a second carbon material, the first carbon material is a porous carbon substrate, the second carbon material perforates the interior of the C / C composite porous material and further perforates the silicon carbon composite material; the second carbon material has at least one dimension greater than 100 nm; A silicon carbon composite material characterized by:

2. The proportion of the second carbon material in the C / C composite porous material is 0.01 to 10 wt. %, and the second carbon material includes at least one of carbon nanotubes, graphene, carbon black, and carbon fibers; Preferably, the second carbon material has a first dimension L that satisfies 100 nm<L<100 μm, and a second dimension a that satisfies 0<a<20 nm; More preferably, L satisfies 100 nm<L<20 μm, and a satisfies 0<a<10 nm.

2. The silicon carbon composite material according to claim 1 .

3. The consolidated specific surface area of ​​the silicon carbon composite material is 1 to 20 times, preferably 1 to 10 times, and more preferably 1 to 5 times the specific surface area of ​​the silicon carbon composite material.

3. The silicon carbon composite material according to claim 1 or claim 2.

4. The pore volume of the C / C composite porous material is 0.2 to 3.0 cm ３ / g, the volume fraction of micropores is greater than 50%, More preferably, the pore volume of the C / C composite porous material is 0.4 to 1.5 cm ３ / g, and the volume fraction of micropores is greater than 70%; 3. The silicon carbon composite material according to claim 1 or claim 2.

5. The diameter of the silicon nanoparticles is 0.5 to 5 nm, and preferably the silicon content in the silicon carbon composite material is 5 to 80 wt. %.

3. The silicon carbon composite material according to claim 1 or claim 2.

6. Further comprising heteroatoms X located within the pores of the C / C composite porous material, the heteroatoms X comprising at least one of B, N, P, O, and S, and the heteroatoms X forming Si-X chemical bonds with silicon atoms in the silicon nanoparticles to separate and encapsulate the silicon nanoparticles; Preferably, the content of the heteroatom in the silicon carbon composite material is 0 to 10 wt. %.

2. The silicon carbon composite material according to claim 1 .

7. The surfaces of the silicon carbon composite particles have a coating layer, and preferably the material of the surface coating layer is one or more selected from the group consisting of solid electrolytes, conductive polymers, carbonaceous materials, metals, alloys, metal oxides, metal halides, metal sulfides, metal phosphates, borates, sulfates, nitrates, and polyoxometalates.

2. The silicon carbon composite material according to claim 1 .

8. The surface of the silicon carbon composite particle has a coating layer with a lattice structure, and preferably, the material of the coating layer contains at least one of carbon nanotube, graphene, carbon black, and carbon fiber.

8. The silicon carbon composite material according to claim 7.

9. The specific surface area of ​​the silicon carbon composite material is 0.1 to 50 m ２ / g, and the pore volume is 0.01 to 0.5 cm ３ / g, Preferably, the specific surface area of ​​the silicon carbon composite material is 0.1 to 10 m ２ / g, and the pore volume is 0.01 to 0.1 cm ３ / g, and / or The true density of the silicon carbon composite material is 1.3 to 2.0 g / cm ３ and the closed pore volume is 0.01 to 0.25 cm ３ / g, 2. The silicon carbon composite material according to claim 1 .

10. A method for producing the silicon carbon composite material according to any one of claims 1 to 9, comprising: Step S1: providing a C / C composite porous material including a first carbon material and a second carbon material, the first carbon material being a porous carbon substrate, and the second carbon material penetrating the interior of the C / C composite porous material; and step S2 of contacting the C / C composite porous material with a silicon-containing precursor and carrying out chemical vapor deposition to distribute silicon nanoparticles in the pores and on the surface of the C / C composite porous material, thereby obtaining the silicon carbon composite material; The C / C composite porous material, the first carbon material, the second carbon material, and the silicon nanoparticles have the same meanings as in claims 1 to 9, respectively. A method for producing a silicon carbon composite material, comprising:

11. The method for producing the C / C composite porous material includes introducing a second carbon material into at least one of different production steps in a process for producing a porous carbon material, the production steps including a carbon precursor step, a carbon precursor pre-stabilization step, a carbonization step, a further pore-forming step, and a finished carbon material step; Preferably, the first carbon material precursor and the second carbon material are mixed, and the mixture is sintered in an inert atmosphere or a mixed atmosphere of an inert gas and an oxygen-containing gas to obtain a C / C composite porous material; or sintering a first carbon material precursor in an inert atmosphere to obtain a first carbon material; mixing the first carbon material with a second carbon material and sintering the mixture to obtain a C / C composite porous material; the first carbonaceous material precursor comprises at least one of a polymer precursor, a biomass precursor, and a fossil carbon source; The method according to claim 10 .

12. In step S2, the contact temperature between the silicon-containing precursor and the C / C composite porous material is 150°C to 1000°C, and the contact time is 1 to 100 hours; and / or When contacting the silicon-containing precursor with the C / C composite porous material, a heteroatom-containing precursor is introduced, and the temperature of contacting the silicon-containing precursor and the heteroatom-containing precursor with the C / C composite porous material is 150°C to 1000°C, and the time is 1 to 100 hours; and / or The silicon-containing precursor comprises at least one of monosilane, disilane, trisilane, halogenated silane, polysilane, silole and its derivatives, and silafluorene and its derivatives; and / or the heteroatom-containing precursor comprises at least one of a nitrogen-containing precursor, a phosphorus-containing precursor, a sulfur-containing precursor, and a boron-containing precursor; The method according to claim 10 .

13. A negative electrode comprising the silicon carbon composite material according to any one of claims 1 to 9, or a silicon carbon composite material obtained by the manufacturing method according to any one of claims 10 to 12.

14. A battery comprising a positive electrode, a negative electrode containing the silicon carbon composite material according to any one of claims 1 to 9 or the silicon carbon composite material obtained by the manufacturing method according to any one of claims 10 to 12, an electrolyte, and a separator.

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