Preparation method, application of a porous carbon material rich in micro-nano through holes, and gas-phase silicon-carbon composite material

Abstract

The present invention discloses a preparation method, application, and vapor-phase silicon-carbon composite material rich in micro-nano through-pores. A foaming agent and a carbon source are uniformly mixed and then isostatically pressed. The resulting isostatically pressed blocks are crushed to obtain coarse crushed particles. The crushed coarse crushed particles are then vacuum sintered under the protection of an inert gas to obtain primary particles. Finally, the primary particles are crushed to obtain a porous carbon material rich in micro-nano through-pores. The porous carbon skeleton rich in micro-nano through-pores prepared in the present invention has abundant micro-nano pores, and most of the pores are non-enclosed through-pore structures, which facilitates the uniform filling of vapor-deposited nano-silicon particles into the pores to form a composite structure with uniform silicon-carbon bonding.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon material preparation and lithium ion battery, and in particular relates to a preparation method and application of a porous carbon material rich in micro-nano through-pores and a gas-phase silicon-carbon composite material. Background Art

[0002] After more than a decade of development, lithium-ion batteries have reached a bottleneck in increasing their energy density. The primary issue is that the lithium storage capacity of commercialized positive and negative electrode materials has essentially reached its theoretical limit. Graphite carbon-based negative electrode materials have already reached a capacity of 360mAh / g, close to the theoretical value of 372mAh / g, leaving very little room for improvement. To achieve even higher energy density, silicon-based materials, with a theoretical gram capacity of up to 4200mAh / g, have garnered widespread attention. Compared to graphite materials, silicon-based materials boast a theoretical energy density more than 10 times greater and are considered one of the most promising high-capacity negative electrode materials for lithium-ion batteries.

[0003] The main challenge with silicon anode materials is their large expansion rate, which can reach 300%. This large expansion rate ultimately leads to pulverization of the active material and destruction of the surface SEI film during use, resulting in poor cycle performance. Furthermore, due to silicon's semiconductor properties, its conductivity is also poor, resulting in poor rate performance. Therefore, the practical application of silicon anode materials in lithium-ion batteries still faces significant challenges. Summary of the Invention

[0004] In order to overcome the problems in the prior art, the present invention provides a preparation method, application and vapor-phase silicon-carbon composite material of a porous carbon material rich in micro-nano through-pores. The porous carbon skeleton has abundant micro-nano pores, and most of the pores are non-closed through-pore structures, which are conducive to the uniform filling of vapor-phase deposited nano-silicon particles into the pores to form a composite structure with uniform silicon-carbon bonding. The porous carbon material provides a buffer structure for silicon expansion, solving the problems of particle pulverization of silicon materials and repeated growth of surface SEI film.

[0005] In order to solve the above technical problems, the technical solutions proposed by the present invention are as follows:

[0006] The present invention provides a method for preparing a porous carbon material rich in micro-nano through pores, comprising the following steps.

[0007] S1. Mix the foaming agent and the carbon source uniformly and perform isostatic pressing to obtain an isostatic pressed block; the isostatic pressing pressure is 50-300 MPa and the processing time is 60-120 min.

[0008] S2. Crushing the isostatically pressed blocks obtained in step S1 to obtain crushed coarse particles.

[0009] S3. The crushed coarse particles in step S2 are subjected to vacuum sintering treatment under the protection of inert gas to obtain primary particles; the sintering temperature of the vacuum sintering is 600-900° C., the vacuum degree is maintained at -(1.0±0.5) KPa, and the temperature is kept for 60-120 minutes.

[0010] S4, crushing the original particles in step S3 to obtain a porous carbon material rich in micro-nano pores.

[0011] In the present invention, an isostatic pressing process is used to tightly bind the sintered pore-forming carbon source powder to form a dense structure, preventing the presence of naturally formed large pores within the material. Simultaneously, a small amount of foaming agent is added to perform vacuum sintering to foam and create pores. During the vacuum sintering process, the foaming agent is heated to form a volatilized gas, forming a large number of pores. Furthermore, under vacuum conditions, the high vapor pressure gas within the sintered material can effectively escape to the outside, opening up the internal pores. This results in a porous carbon structure with micro-nanopores after sintering. Increasing the proportion of foaming agent increases the pore size of the material.

[0012] As an optional embodiment, in the preparation method provided by the present invention, the foaming agent is selected from one or more of sodium bicarbonate, sodium carbonate, azodicarbonamide or carbon black; and the particle size D50 of the foaming agent is 1-10 μm.

[0013] The particle size D50 of the foaming agent is 1~10μm. In principle, the smaller the particle size, the more conducive it is to dispersion with the carbon source. However, the smaller the particles, the more difficult it is to process. Therefore, the particle size is limited to within 10 microns, which is conducive to dispersion and easy to process.

[0014] In the present invention, the volatilized gas of the foaming agent during the high-temperature sintering process can form a large number of internal pores, and due to the vacuum condition, the internal gas can escape to the outside due to the high pressure difference, which is conducive to forming a porous structure with through holes.

[0015] As an optional embodiment, in the preparation method provided by the present invention, the carbon source is selected from one or more of asphalt, resin or organic polymer, and the particle size D50 of the carbon source is 1-30 μm.

[0016] As an optional embodiment, in the preparation method provided by the present invention, in step S1, the mass ratio of the foaming agent to the carbon source is (0.1~0.5):100.

[0017] In the present invention, controlling the mass ratio of the foaming agent to the carbon source within the above range is conducive to forming the most excellent pores.

[0018] As an optional embodiment, in the preparation method provided by the present invention, in step S2, the size of the crushed coarse particles is 3-10 mm.

[0019] As an optional embodiment, in the preparation method provided by the present invention, in step S3, the heating rate during vacuum sintering is 0.5-5°C / min.

[0020] As an optional embodiment, in the preparation method provided by the present invention, the pore diameter of the prepared porous carbon material rich in micro-nano pores is 0.5-10.0 nm; and the pore volume accounts for 60-90%.

[0021] Based on the same technical concept, the present invention also provides the application of the porous carbon material rich in micro-nano through-pores prepared by the above preparation method in silicon-carbon composite materials or in lithium-ion batteries.

[0022] Based on the same technical concept, the present invention also provides a gas-phase silicon-carbon composite material, which is obtained by subjecting the porous carbon material rich in micro-nano through-pores prepared above to silane chemical vapor deposition.

[0023] In this invention, nanosilicon is deposited into porous carbon with a rich micro-nanopore structure via vapor deposition. This porous carbon material, rich in micro-nanopores, provides a high-quality substrate for the vapor-phase silicon and a flexible carrier for the silicon particles, suppressing their significant volume expansion during charge and discharge. Furthermore, the preponderance of nanopores effectively protects the silicon particles from direct contact with the electrolyte, reducing side reactions on the silicon particle surface. Ultimately, this porous structure results in a vapor-phase silicon-carbon composite material with excellent performance.

[0024] As an optional embodiment, in the gas-phase silicon-carbon composite material provided by the present invention, the temperature of the silane chemical vapor deposition is (600±100)°C, and the flow ratio of the introduced silane gas to the protective gas is (0.5~1):10.

[0025] As an optional embodiment, in the vapor-phase silicon-carbon composite material provided by the present invention, the mass percentage of vapor-phase deposited silicon (nano-silicon) accounts for 40% to 60% of the total mass.

[0026] Furthermore, the preferred mass percentage is 45%.

[0027] As an optional embodiment, in the vapor-phase silicon-carbon composite material provided by the present invention, the vapor-phase deposition equipment is selected from an atmosphere rotary kiln or a fluidized bed deposition equipment.

[0028] As an optional embodiment, in the gas-phase silicon-carbon composite material provided by the present invention, the silane gas is selected from one or more of monosilane, disilane, trisilane, butasilane, monochlorosilane or dichlorosilane.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The porous carbon rich in micro-nano through-pores in the present invention has a rich micro-nano pore structure, which can provide sufficient carriers for gas-phase nano-silicon particles. In addition, the micro-nano pores are through-holes connected to the outside, which is conducive to the gas-phase deposited silicon particles filling into the pores, avoiding the silicon particles only being deposited on the surface and causing uneven deposition.

[0031] (2) The preparation method of the porous carbon material rich in micro-nano through-pore structure provided by the present invention mainly includes an isostatic pressing process and a vacuum sintering process, wherein the isostatic pressing process allows the carbon source powder to be tightly combined to form a dense structure before sintering to form pores, thereby preventing the existence of naturally formed large pores inside; at the same time, a small amount of foaming agent is added to perform vacuum sintering and foaming to form pores. During the vacuum sintering process, the foaming agent is first heated to form gas volatilization to form a large number of pores. Further, under vacuum conditions, the high vapor pressure gas inside the sintered material can effectively escape to the outside, so that the internal pores can be opened up, that is, a porous structure carbon with micro-nano through-pores is formed after sintering; at the same time, a small amount of foaming agent has very little residue after sintering, and no further special treatment is required, thereby reducing the cost of waste treatment.

[0032] (3) The silicon-carbon material prepared by using the porous carbon material of the present invention can solve the problems of particle pulverization of silicon materials and repeated growth of SEI film on the surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is an electron microscope image of the porous carbon raw material rich in micro-nano through-pore structure prepared in Example 1 of the present invention;

[0035] Figure 2 This is an electron microscope image of the silicon-carbon composite material prepared in Example 1 of the present invention;

[0036] Figure 3 This is a SEM photograph of a cross section of the gas-phase silicon-carbon composite material particles prepared in Example 1 of the present invention;

[0037] Figure 4 : This is a C element distribution diagram of the cross section of the gas-phase silicon-carbon composite material particles prepared in Example 1 of the present invention;

[0038] Figure 5 This is a Si element distribution diagram of the cross section of the gas-phase silicon-carbon composite material particles prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0039] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0040] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0041] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0042] Example 1

[0043] A method for preparing a gas-phase silicon-carbon composite material based on porous carbon rich in micro-nano through-pore structure comprises the following steps:

[0044] (1) Raw material mixing: Take a certain amount of sodium bicarbonate powder (D50≈5μm) and asphalt powder (asphalt PE250, coking value of about 48%, D50≈10μm) and mix them physically; the mass ratio of sodium bicarbonate powder to asphalt powder is 0.2:100; use a high-speed dispersing equipment (model VCH-5L), under nitrogen protection, at a dispersion rate of 500rpm for 20min; then at a dispersion rate of 1000rpm for another 30min; at the same time, keep the circulating cooling water on throughout the process; after the raw materials are mixed, seal them in PE bags for storage.

[0045] (2) Isostatic pressing: The powder from step (1) is filled into a silicone soft mold, which is then vacuum-sealed with a PE bag. The sealed loading mold is placed into an isostatic pressing chamber (ultra-high pressure equipment model 600MPa-5L). The isostatic pressing parameters require a pressure of 200MPa and a holding time of 90min. After the pressing is completed, the PE bag is torn off and the block material in the mold is taken out to obtain the isostatic pressed block material.

[0046] (3) Crushing: The isostatically pressed block material of step (2) is crushed by using a small jaw crusher (model PE100-125), which can be crushed multiple times until the particle size is controlled to be below 10 mm.

[0047] (4) Vacuum sintering: The crushed material from step (3) is vacuum sintered in a vacuum sintering furnace (model HF-RS-A). The temperature control of the vacuum sintering furnace is carried out according to the following requirements: vacuum is first performed before heating, and the temperature is started after the vacuum reaches -1.0 kPa; then the temperature is raised from room temperature to 700 ° C at a heating rate of 1 ° C / min, and the temperature is kept for 120 minutes; after the heating is completed, the heating is turned off and the material is allowed to cool naturally to room temperature. The vacuum degree needs to be maintained in the range of - (1.0 ± 0.5) kPa during the entire sintering process. If the vacuum degree is lower than this range, the vacuum pump is started to evacuate. Thus, a porous carbon raw material with a micro-nano through-hole structure is obtained.

[0048] (5) Crushing: The raw material from step (4) was further crushed in a jet mill (model QLM-1.5) with a particle size D50 controlled at 8.0 ± 2.0 μm to obtain a porous carbon raw powder rich in micro-nano pore structure, named PC1.

[0049] (6) Vapor deposition: The original powder of step (5) was subjected to vapor phase silicon deposition in a fluidized bed apparatus (model FB-100). 5 kg of the original powder was added and high-purity argon was introduced for 30 min at a flow rate of 10 L / min. The temperature was then raised from room temperature to 560°C at a heating rate of 5°C / min. After maintaining the temperature at 560°C for 30 min, monosilane gas was introduced at a flow rate of 0.1 L / min and the high-purity argon flow rate was maintained at 10 L / min. After deposition for 8 h, the introduction of methane gas was stopped and the high-purity argon flow rate was maintained at 10 L / min. The heating was turned off and the mixture was naturally cooled to room temperature. A vapor phase silicon-carbon composite material based on porous carbon rich in micro-nano pore structure was obtained and named SPC1.

[0050] Example 2

[0051] A method for preparing a gas-phase silicon-carbon composite material based on porous carbon rich in micro-nano through-pore structure, which differs from Example 1 in that:

[0052] The sodium bicarbonate powder in step (1) was replaced with sodium carbonate powder (sodium carbonate, D50≈5 μm), with the mass ratio of sodium carbonate powder to asphalt powder being 0.1:100. The medium static pressure parameters in step (2) required a pressure of 100 MPa and a holding time of 120 min. In step (4), the temperature was raised from room temperature to 900°C at a heating rate of 3°C / min and the temperature was held for 100 min. All other steps were consistent with those in Example 1. The obtained porous carbon raw powder rich in micro-nano through-pore structure was named PC2, and the obtained gas-phase silicon-carbon composite material based on the porous carbon rich in micro-nano through-pore structure was named SPC2.

[0053] Example 3

[0054] A method for preparing a gas-phase silicon-carbon composite material based on porous carbon rich in micro-nano through-pore structure, which differs from Example 1 in that:

[0055] The sodium bicarbonate powder in step (1) was replaced with carbon black powder (acetylene black, D50≈1 μm), with the mass ratio of acetylene black powder to asphalt powder being 0.3:100. In step (4), the temperature was raised from room temperature to 600°C at a rate of 1°C / min and maintained for 100 min. The other steps were consistent with those in Example 1. The obtained porous carbon raw powder rich in micro-nano through-pore structure was named PC3, and the obtained gas-phase silicon-carbon composite material based on the porous carbon rich in micro-nano through-pore structure was named SPC3.

[0056] Example 4

[0057] A method for preparing a gas-phase silicon-carbon composite material based on porous carbon rich in micro-nano through-pore structure, which differs from Example 1 in that:

[0058] The asphalt PE250 powder in step (1) was replaced with phenolic resin 2123 powder (phenolic resin 2123, coking value 48%, D50≈13μm), and the mass ratio of sodium bicarbonate powder to phenolic resin powder was 0.4:100. The medium static pressure parameters in step (2) required a pressure of 300MPa and a holding time of 80min. In step (4), the temperature was raised from room temperature to 800°C at a heating rate of 3°C / min and the holding time was 100min. The other steps were consistent with Example 1. The obtained porous carbon raw powder rich in micro-nano through-pore structure was named PC4, and the obtained gas-phase silicon-carbon composite material based on the porous carbon rich in micro-nano through-pore structure was named SPC4.

[0059] Example 5

[0060] A method for preparing a gas-phase silicon-carbon composite material based on porous carbon rich in micro-nano through-pore structure, which differs from Example 1 in that:

[0061] The asphalt PE250 powder in step (1) was replaced with nylon powder (nylon 66, coking value 48%, D50≈10 μm), and the mass ratio of sodium bicarbonate powder to nylon powder was 0.5:100; the other steps were consistent with Example 1. The obtained porous carbon raw powder rich in micro-nano through-pore structure was named PC5, and the obtained gas-phase silicon-carbon composite material based on the porous carbon rich in micro-nano through-pore structure was named SPC5.

[0062] Comparative Example 1

[0063] A method for preparing a gas-phase silicon-carbon composite material based on porous carbon material is different from Example 1 in that:

[0064] The amount of foaming agent added in step (1) is 0, and the other steps are consistent with Example 1. The obtained porous carbon raw powder is named PC6, and the obtained gas-phase silicon-carbon composite material based on porous carbon is named SPC6.

[0065] Comparative Example 2

[0066] A method for preparing a gas-phase silicon-carbon composite material based on porous carbon material is different from Example 1 in that:

[0067] The vacuum sintering in step (4) was replaced with atmospheric pressure sintering. The maximum sintering temperature and temperature rise schedule for atmospheric pressure sintering were consistent with those in Example 1. The vacuum environment was changed to nitrogen as a protective gas throughout the process, with a flow rate of 1.0 L / min. The other steps were consistent with those in Example 1. The obtained porous carbon raw powder was named PC7, and the obtained gas-phase silicon-carbon composite material based on porous carbon was named SPC7.

[0068] Comparative Example 3

[0069] A method for preparing a gas-phase silicon-carbon composite material based on porous carbon material is different from Example 1 in that:

[0070] In step (1), a higher amount of sodium bicarbonate was added, with the mass ratio of sodium bicarbonate powder to asphalt powder being 1.0:100; the other parameters remained unchanged. All other parameters and steps were consistent with those in Example 1. The obtained porous carbon raw powder was named PC8, and the obtained porous carbon-based fumed silicon-carbon composite material was named SPC8.

[0071] Comparative Example 4

[0072] A method for preparing a gas-phase silicon-carbon composite material based on porous carbon material is different from Example 1 in that:

[0073] In step (2), isostatic pressing is not performed, and step (4) is directly performed for sintering after mixing in step (1). The other steps are the same as those in Example 1. The obtained porous carbon raw powder is named PC9, and the obtained gas phase silicon-carbon composite material based on porous carbon is named SPC9.

[0074] 1. Preparation of button electrode

[0075] Electrode preparation: The gas-phase silicon-carbon composite materials prepared in the above embodiments and comparative examples were respectively mixed with the conductive agent SP, the binder LA133, and deionized water in a certain proportion to form a uniform slurry, wherein the mass ratio of silicon-carbon negative electrode material: conductive agent SP: binder LA133 was 60:20:20; the slurry was prepared using a vacuum degassing machine with a rotation speed of 2000 rpm and a time of 10 min.

[0076] The prepared slurry is evenly applied on the copper foil, and then placed in a 100°C forced air drying oven for drying; the baked electrode is cut and pressed into a circular electrode of a certain size, accurately weighed (accurate to 0.0001g), placed in a vacuum drying oven, and baked at 120°C for 8 hours under vacuum conditions to obtain a button electrode.

[0077] The button battery assembled with the corresponding SPC1 material is recorded as SC1 button battery, and by analogy, seven types of button batteries SPC1 to SPC9 are obtained.

[0078] 2. Performance Testing

[0079] 1. Performance testing of gas-phase silicon-carbon composite materials based on porous carbon rich in micro-nano through-pore structure.

[0080] The pore volume and pore size of the porous carbon raw materials rich in micro-nano pore structure prepared in the above examples and comparative examples were tested, and the results are shown in Table 1.

[0081] Table 1: Pore structure of porous carbon

[0082]

[0083] The porous carbon materials prepared in Comparative Examples 2-4 lack micro-nanostructured porous carbon materials (PC7 to PC9 in Table 1). In contrast, the porous carbon materials prepared in Examples 1-5 possess abundant micro-nanostructured porous carbon (PC1 to PC5 in Table 1). Micro-nanopore volume accounts for a larger proportion of the pore volume under the precursor with a larger total pore volume. Simultaneously, the abundant pore structure also results in a larger specific surface area. Among the porous carbons possessing both micro-nanostructures, the micro-nanoporous carbon with a through-pore structure (PC1 in Table 1) exhibits a larger total pore volume and specific surface area than the micro-nanostructured porous carbon without through-pores (PC6 in Table 1).

[0084] Scanning electron microscopy (SEM) was performed on the porous carbon raw material rich in micro-nano through-pore structure prepared in Example 1 and the silicon-carbon composite material obtained by vapor deposition of silicon. Figure 1-2 As shown, Figure 1 The morphology of the porous carbon raw material is rich in micro-nano through-pore structure. Figure 2 This is the morphology of the silicon-carbon composite material obtained by vapor deposition of silicon on a porous carbon substrate rich in micro-nano pore structure. Figure 3 This is the SEM photo of the cross section of the gas phase silicon carbon composite material particles. Figure 4 is the C element distribution diagram of the cross section of the gas phase silicon carbon composite material particle, Figure 5 This is the Si element distribution diagram of the cross section of the gas phase silicon-carbon composite material particles.

[0085] 2. Performance test of button electrode

[0086] The assembled batteries were subjected to an open circuit voltage test, and batteries with an open circuit voltage above 2.5V were selected for 0.1C first charge and discharge efficiency and reversible capacity tests. The electrical performance comparison of several batteries is shown in Table 2.

[0087] Table 2: Electrical properties of button cells

[0088]

[0089] In the application of lithium-ion batteries, silicon-based negative electrode materials consume more irreversible lithium and relatively less reversible lithium due to large volume changes, particle pulverization of silicon materials and repeated growth of SEI film on the surface. This is directly reflected in the high lithium insertion capacity and relatively low reversible lithium removal capacity in lithium batteries, resulting in low initial charge and discharge efficiency. As can be seen from the above table, the porous carbon-filled nanosilicon structure based on micro-nano through-pore structure constructed in the present invention has abundant micro-nano pores that provide an elastic carbon skeleton for the expansion and contraction of nanosilicon during lithium insertion and removal, which can prevent the breakage of silicon particles. At the same time, the inner wall of the porous carbon micro-nano pore is tightly combined with the nanosilicon particles, which on the one hand increases the electronic conductivity of the silicon particles and the carbon skeleton, that is, the entire composite particle. On the other hand, the inner wall of the carbon pore tightly wraps the silicon particles, reducing the direct contact reaction between the electrolyte and the nanosilicon, that is, reducing the repeated formation of SEI film on the surface of the silicon particles and causing the loss of reversible lithium. Compared with the gas-phase silicon-carbon composite materials without a porous carbon skeleton with a micro-nano pore structure (such as SPC7, SPC8 and SPC9 in the table) and the gas-phase silicon-carbon composite materials with a porous carbon skeleton with micro-nano pores but non-through-pore structure (such as SPC6 in the table), the electrical properties of the gas-phase silicon-carbon composite materials with this structure (such as SPC1 to SPC5 in the table) are greatly improved; the gas-phase silicon-carbon composite material based on porous carbon rich in micro-nano through-pore structure finally prepared by the present invention has a market-competitive electrical performance level in the application field of lithium-ion battery negative electrodes.

[0090] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a porous carbon material rich in micro-nano pores, characterized in that: The following steps are involved: S1. Mixing a foaming agent and a carbon source uniformly and performing isostatic pressing to obtain an isostatic pressed block; the isostatic pressing pressure is 50-300 MPa, and the processing time is 60-120 min; the mass ratio of the foaming agent to the carbon source is (0.1-0.5):100; S2, crushing the isostatically pressed blocks obtained in step S1 to obtain crushed coarse particles; S3. The crushed coarse particles in step S2 are subjected to vacuum sintering treatment under the protection of inert gas to obtain primary particles; the vacuum sintering temperature is 600-900° C., the vacuum degree is maintained at -(1.0±0.5) KPa, and the temperature is kept for 60-120 minutes; S4, crushing the original particles in step S3 to obtain a porous carbon material rich in micro-nano pores.

2. The method for preparing a porous carbon material rich in micro-nano pores according to claim 1, characterized in that: The foaming agent is selected from one or more of sodium bicarbonate, sodium carbonate, azodicarbonamide or carbon black; and the particle size D50 of the foaming agent is 1-10 μm.

3. The method for preparing a porous carbon material rich in micro-nano pores according to claim 1, characterized in that: The carbon source is selected from one or more of asphalt, resin or organic polymer, and the particle size D50 of the carbon source is 1-30 μm.

4. The method for preparing a porous carbon material rich in micro-nano pores according to claim 1, characterized in that: In step S2, the size of the crushed coarse particles is 3-10 mm.

5. The method for preparing a porous carbon material rich in micro-nano pores according to claim 1, characterized in that: In step S3, the heating rate during vacuum sintering is 0.5-5°C / min.

6. The method for preparing a porous carbon material rich in micro-nano pores according to claim 1, characterized in that: The prepared porous carbon material rich in micro-nano pores has a pore diameter of 0.5~10.0nm; the pore volume accounts for 60~90%.

7. Use of the porous carbon material rich in micro-nano through-pores prepared by the preparation method according to any one of claims 1 to 6 in silicon-carbon composite materials or lithium-ion batteries.

8. A gas phase silicon-carbon composite material, characterized in that: The gas-phase silicon-carbon composite material is obtained by subjecting a porous carbon material rich in micro-nano through-pores prepared by the preparation method according to any one of claims 1 to 6 to silane chemical vapor deposition.

9. The gas-phase silicon-carbon composite material according to claim 8, characterized in that The temperature of the silane chemical vapor deposition is (600±100)°C, the flow ratio of the introduced silane gas to the shielding gas is (0.5-1):10, and the mass percentage of the vapor-deposited silicon accounts for 40%-60% of the total mass.

Images