A silicon-carbon composite material based on steam explosion, its preparation method and its application

Abstract

This invention provides a silicon-carbon composite material based on steam explosion, its preparation method, and its application, belonging to the field of silicon-carbon composite material technology. The preparation method includes the steps of preparing a precursor composite slurry, steam explosion, and simultaneous carbonization and activation. The steam explosion treatment step involves pumping the precursor composite slurry into a steam explosion reactor, introducing saturated steam, and maintaining pressure at 200-280℃ and 2.0-4.5MPa for 30-40 minutes. During the pressure maintenance, ultrasonic assistance is activated. After the pressure maintenance, a step-by-step depressurization is performed, i.e., 3-8 depressurizations are completed within 6-10 seconds, with each depressurization pressure being 10-30% of the previous one. After each depressurization, the pressure is held momentarily for 0.1-0.2 seconds, and finally completely depressurized to atmospheric pressure. After drying, the exploded product is obtained. The silicon-carbon composite material obtained by the method of this invention exhibits excellent cycle performance and rate performance when applied to batteries.

Description

Technical Field

[0001] This invention belongs to the field of carbon-silicon composite material technology, specifically relating to a silicon-carbon composite material based on steam explosion, its preparation method, and its application. Background Technology

[0002] With the transformation of the global energy structure, electric vehicles and large-scale energy storage systems have placed unprecedented demands on the energy density, cycle life, and safety of lithium-ion batteries. Graphite, as the current mainstream commercial anode material, has a theoretical specific capacity of only 372 mAh / g, which is insufficient to meet the needs of next-generation high-energy batteries. Silicon, with its extremely high theoretical specific capacity (about 4200 mAh / g, more than ten times that of commercial graphite), abundant crustal reserves, and environmental friendliness, is regarded as the most promising core material for next-generation anode materials. Silicon-carbon composite materials formed by combining silicon with carbon materials are the mainstream research and development direction that balances high capacity and structural stability.

[0003] However, silicon undergoes a massive volume expansion of over 300% during alloying / dealloying. This inherent defect triggers a series of chain problems, severely restricting its commercial application. On the one hand, repeated volume expansion and contraction can cause silicon particles to crack, pulverize, and damage the overall structural integrity of the electrode material. On the other hand, volume changes cause the solid electrolyte interface film on the electrode surface to continuously rupture and regenerate, which not only consumes a large number of active lithium ions but also increases the interface resistance, ultimately leading to rapid capacity decay, significantly shortened cycle life, and even safety hazards such as internal short circuits and failures.

[0004] To overcome the technical bottlenecks of silicon-based anodes, researchers have conducted extensive studies. Their solutions primarily involve nano-manipulation of silicon to mitigate structural damage caused by volume expansion, or compositing it with carbon materials to construct a conductive network with a buffer structure. However, these specific technical solutions have the following drawbacks:

[0005] Option 1: Prepare nano-silicon using methods such as chemical vapor deposition and magnesia reduction. This method can achieve precise control of silicon particle size, alleviate volume expansion stress to a certain extent, and shorten lithium-ion transport distance. However, the above methods generally have problems such as demanding equipment requirements, high cost, complex processes, and low yield, making it difficult to achieve large-scale industrial production.

[0006] Option 2: Mechanically nano-sized silicon and mixed with carbon through high-energy ball milling. This method is relatively convenient to operate, does not require complex high-temperature and high-pressure equipment, and can achieve rapid refinement of silicon particles. However, impurities are easily introduced during the ball milling process, and it is difficult to achieve uniform dispersion of silicon and carbon materials by using only mechanical mixing methods. Problems such as silicon particle agglomeration and uneven distribution of carbon materials are likely to occur, resulting in local stress concentration inside the composite material. This cannot effectively buffer the volume expansion of silicon, and the conductive network is discontinuous, which affects the electron transport efficiency of the electrode and reduces the cycle stability of the battery.

[0007] Option 3: Construct fine carbon-silicon composite structures such as yolk-shell, core-shell, and porous structures through complex template or chemical etching methods. This can precisely control the morphology and pore structure of the composite material and provide sufficient buffer space for the volume expansion of silicon. However, the process is complicated, the preparation cycle is long, and the process controllability is poor. This not only increases the production cost but also causes product performance fluctuations and poor batch stability.

[0008] More importantly, existing methods mostly follow a "step-by-step integration" approach, which involves first preparing the active components and then constructing the buffer structure. This process is lengthy, and the interface effects of each step accumulate, making it difficult to achieve precise control and integrated construction of the material's internal structure.

[0009] Steam explosion technology is a physical-chemical process enhancement technology that uses high-temperature and high-pressure steam to permeate materials and release the pressure instantaneously, thereby achieving material structure dissociation through adiabatic expansion. It is widely used in biomass fiber separation, and its core value lies in its ability to simultaneously achieve mechanical crushing, thermochemical modification, and structural reorganization within milliseconds.

[0010] However, this technology is still lacking in the field of high-end electrode materials, especially in the preparation of "structure-function integrated" composite materials to solve the problem of volume expansion.

[0011] Therefore, providing a silicon-carbon composite material, its preparation method, and its application, based on steam explosion technology, gives it a unique gradient composite structure. When applied to batteries, it exhibits excellent rate performance and cycle performance, which has become a new research topic for engineers. Summary of the Invention

[0012] To address the technical problems existing in the prior art, this invention provides a silicon-carbon composite material based on steam explosion, its preparation method, and its application. This invention overcomes the shortcomings of the prior art, such as lengthy process flow, limited structural buffering effect, weak interfacial bonding, and high cost. The prepared silicon-carbon composite material has a unique "core-shell-buffer layer" gradient structure, providing sufficient buffer space for the volume expansion of silicon. When applied to batteries, it exhibits excellent rate performance and cycle performance, effectively extending battery life.

[0013] To address the aforementioned technical problems, the present invention adopts the following technical solution:

[0014] A method for preparing silicon-carbon composite materials based on steam explosion includes the steps of preparing precursor composite slurry, steam explosion, simultaneous carbonization and activation, as detailed below:

[0015] 1. Preparation of precursor composite slurry

[0016] Add silicon powder to a 74-78 wt% ethanol solution and stir at 180-200 rpm for 10-15 min. Add carbon precursor solution at a rate of 1.0-1.2 g / min while stirring at 180-200 rpm. After addition, continue stirring for 35-40 min to obtain precursor composite slurry.

[0017] The silicon powder has a particle size of 0.5-5 μm;

[0018] The mass ratio of silicon powder to ethanol solution is 15-20:7.5-320;

[0019] The carbon precursor solution is prepared by adding the first carbon precursor and the second carbon precursor to a 74-78 wt% ethanol solution and stirring at 180-200 rpm for 5-10 min.

[0020] In the carbon precursor solution, the mass ratio of ethanol solution to total carbon precursor is 1:1;

[0021] The total carbon precursor is the sum of the first carbon precursor and the second carbon precursor;

[0022] The mass ratio of the first carbon precursor to the second carbon precursor is 0.5-2:1;

[0023] The mass ratio of silicon powder to total carbon precursor is 0.25-2:1;

[0024] The first carbon precursor is one of high-temperature asphalt and phenolic resin, with a particle size of 50-80 μm;

[0025] The high-temperature asphalt has a softening point of 85-95℃, an ash content of 0.1-0.2wt%, and a quinoline-insoluble content of 6-8wt%.

[0026] The molecular weight of the phenolic resin is 800-1500;

[0027] The second carbon precursor is one of sodium lignosulfonate, chitosan, and corn starch;

[0028] The particle size of the chitosan and corn starch is 120-150 mesh;

[0029] The degree of deacetylation of the chitosan is 85-90%.

[0030] 2. Steam explosion treatment

[0031] The precursor composite slurry was pumped into a steam explosion reactor, and saturated steam was introduced. The reactor was pressurized at 200-280℃ and 2.0-4.5MPa for 30-40 minutes. During pressurization, ultrasonic assistance was initiated, with a controlled frequency of 40-80kHz and a power density of 0.3-1.0W / cm³. 3 After the pressure maintenance is completed, a step-by-step pressure release is carried out, that is, 3-8 pressure releases are completed within 6-10 seconds, each pressure release is 10-30% of the previous pressure, and the pressure is held for 0.1-0.2 seconds after each pressure release, and finally completely released to atmospheric pressure (the pressure mentioned is gauge pressure, that is, the gauge pressure of atmospheric pressure is 0). After drying, the explosive product is obtained.

[0032] 3. Simultaneous carbonization and activation

[0033] The explosive material is placed in a pyrolysis furnace and carbonized under an argon atmosphere by programmed temperature increase. The temperature is increased at 2-5℃ / min to 500-700℃ and held for 10-30 min to fully decompose and create pores in the second carbon precursor. Then, the temperature is increased at 5-10℃ / min to 900-1200℃ and held for 1-3 h to fully graphitize the first carbon precursor and achieve in-situ self-activation. After cooling, a silicon-carbon composite material is obtained.

[0034] A silicon-carbon composite material based on steam explosion was prepared using the aforementioned method.

[0035] A silicon-carbon composite material based on steam explosion, when applied to batteries, exhibits excellent overall electrochemical performance.

[0036] This invention employs a first carbon precursor and a second carbon precursor as dual carbon sources. The first carbon precursor, after carbonization, exhibits a high degree of graphitization and high mechanical strength, serving to form a dense confinement layer. The second carbon precursor, with a high oxygen content, generates more gas after carbonization, resulting in a soft carbon matrix, which serves to form a porous buffer layer. This dual carbon source design creates a gradient buffer structure that is "rigid inside and flexible outside." The dense inner carbon shell strongly confines the expansion of the silicon core, preventing pulverization, while the porous, soft outer carbon matrix absorbs overall strain and provides a rapid ion transport channel. The two work synergistically to achieve multi-stage dissipation of volume expansion; combined with vibration... The oscillating blasting process results in more uniform silicon fragmentation, avoiding the over-crushing and unevenness issues associated with single blasting. The pulsed stress generated is more conducive to the formation of hierarchical channels in the carbon matrix. Ultrasonic assistance generates cavitation and micro-stirring during the micro-pressure stage, promoting the micron-level dispersion of the precursor and pre-weakening the silicon particles, reducing crushing energy consumption and resulting in a narrower final silicon core size distribution. Combined with the simultaneous carbonization and activation steps, the highly active surface of the soft carbon matrix and the ability to form a stable SEI film effectively improve cycle performance and rate performance, and extend battery life when applied to batteries.

[0037] This invention utilizes a synergistic approach of "multi-field coupled oscillating steam explosion" and "dual carbon source gradient design" to prepare a uniquely structured and high-performance silicon-carbon composite material in a single step. During the preparation process, native micron-sized silicon particles are broken into quasi-spherical silicon nanoparticles. Each silicon nanoparticle is encased in a dense, continuous graphitized carbon shell, forming a core-shell unit. Numerous core-shell units are uniformly embedded in a three-dimensionally interconnected soft carbon matrix (derived from a second carbon precursor) rich in macropores and mesopores. The soft carbon matrix contains cavities, which are pre-formed buffer spaces created by the combined action of steam explosion and carbon precursor decomposition, providing ample space for silicon. This invention seamlessly integrates multiple key steps, including nanostructuring, compositing, pore formation, carbonization, activation, and interface strengthening, into a simplified process of "oscillating steam explosion + simultaneous pyrolysis." The resulting silicon-carbon composite material, when applied to batteries, exhibits excellent electrochemical performance and a long service life, significantly reducing energy consumption and cost, and showing broad prospects for large-scale production.

[0038] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0039] 1. The silicon-carbon composite material of the present invention is applied to a CR2032 coin cell. Cyclic performance tests were conducted at a current density of 0.5C (1C=2000mA / g). The reversible capacity in the first cycle was 1566-1580mAh / g, the capacity retention rate after 200 cycles was 95.4-96.2%, and the capacity retention rate after 500 cycles was 92.3-93.6%.

[0040] 2. When the silicon-carbon composite material of the present invention is applied to the CR2032 coin cell, the discharge capacity is 1631-1650 mAh / g at 0.2C, 1514-1552 mAh / g at 0.5C, 1374-1423 mAh / g at 1C, 1226-1285 mAh / g at 2C, 982-1054 mAh / g at 5C, and 1584-1623 mAh / g when returning to 0.2C. Detailed Implementation

[0041] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described.

[0042] Example 1

[0043] 1. Preparation of precursor composite slurry

[0044] 18g of silicon powder was added to 36g of 78wt% ethanol solution and stirred at 200rpm for 13min. Then, 36g of carbon precursor solution was added at a rate of 1.0g / min while stirring at 200rpm. After the addition was completed, stirring was continued for 37min to obtain the precursor composite slurry.

[0045] The silicon powder has a particle size of 2.5 μm;

[0046] The carbon precursor solution was prepared by adding 9g of high-temperature pitch and 9g of sodium lignosulfonate to 18g of 78wt% ethanol solution and stirring at 200rpm for 8min.

[0047] The high-temperature asphalt has a softening point of 90℃, an ash content of 0.1wt%, a quinoline insoluble content of 7wt%, and a particle size of 70μm.

[0048] 2. Steam explosion treatment

[0049] The precursor composite slurry was pumped into a steam explosion reactor, and saturated steam was introduced. The reactor was pressurized at 240℃ and 3.5 MPa for 35 minutes. During this pressurization period, ultrasonic assistance was initiated, with a controlled frequency of 60 kHz and a power density of 0.6 W / cm³. 3 After the pressure maintenance is completed, a step-by-step depressurization is carried out, that is, five depressurizations are completed within 6 seconds, each depressurization pressure is 20% of the previous pressure, and the pressure is held for 0.1 seconds after each depressurization, and finally completely depressurized to atmospheric pressure (the pressure mentioned is gauge pressure, that is, the gauge pressure of atmospheric pressure is 0). After drying, the explosive product is obtained.

[0050] 3. Simultaneous carbonization and activation

[0051] The explosive material was placed in a pyrolysis furnace and carbonized under an argon atmosphere by programmed temperature increase. The temperature was increased to 600℃ at 3.5℃ / min and held for 20 min to fully decompose and create pores in the second carbon precursor. Then, the temperature was increased to 1100℃ at 7℃ / min and held for 2 h to fully graphitize the first carbon precursor and achieve in-situ self-activation. After cooling, a silicon-carbon composite material was obtained.

[0052] Example 2

[0053] 1. Preparation of precursor composite slurry

[0054] Add 15g of silicon powder to 7.5g of 74wt% ethanol solution and stir at 180rpm for 15min. Add 15g of carbon precursor solution at a rate of 1.2g / min while stirring at 180rpm. After addition, continue stirring for 40min to obtain precursor composite slurry.

[0055] The silicon powder has a particle size of 0.5 μm;

[0056] The carbon precursor solution was prepared by adding 2.5g of phenolic resin and 5g of chitosan to 7.5g of 74wt% ethanol solution and stirring at 180rpm for 10min.

[0057] The phenolic resin has a molecular weight of 800 and a particle size of 50 μm.

[0058] The chitosan has a degree of deacetylation of 88% and a particle size of 120 mesh.

[0059] 2. Steam explosion treatment

[0060] The precursor composite slurry was pumped into a steam explosion reactor, and saturated steam was introduced. The reactor was pressurized at 200℃ and 2.0 MPa for 40 minutes. During this pressurization period, ultrasonic assistance was initiated, with a controlled frequency of 40 kHz and a power density of 0.3 W / cm³. 3 After the pressure maintenance is completed, a step-by-step depressurization is carried out, that is, three depressurizations are completed within 8 seconds, each depressurization pressure is 10% of the previous pressure, and the pressure is held for 0.2 seconds after each depressurization, and finally completely depressurized to atmospheric pressure (the pressure mentioned is gauge pressure, that is, the gauge pressure of atmospheric pressure is 0). After drying, the explosive product is obtained.

[0061] 3. Simultaneous carbonization and activation

[0062] The explosive material was placed in a pyrolysis furnace and carbonized under an argon atmosphere by programmed temperature increase. The temperature was increased to 600℃ at 3.5℃ / min and held for 20 min to fully decompose and create pores in the second carbon precursor. Then, the temperature was increased to 1100℃ at 7℃ / min and held for 2 h to fully graphitize the first carbon precursor and achieve in-situ self-activation. After cooling, a silicon-carbon composite material was obtained.

[0063] Example 3

[0064] 1. Preparation of precursor composite slurry

[0065] Add 20g of silicon powder to 320g of 78wt% ethanol solution and stir at 200rpm for 10min. Add 280g of carbon precursor solution at a rate of 1.0g / min while stirring at 200rpm. After addition, continue stirring for 35min to obtain precursor composite slurry.

[0066] The silicon powder has a particle size of 5 μm;

[0067] The carbon precursor solution was prepared by adding 53g of phenolic resin and 27g of corn starch to 80g of 78wt% ethanol solution and stirring at 200rpm for 5min.

[0068] The phenolic resin has a molecular weight of 1500 and a particle size of 80 μm.

[0069] The corn starch has a particle size of 150 mesh.

[0070] 2. Steam explosion treatment

[0071] The precursor composite slurry was pumped into a steam explosion reactor, and saturated steam was introduced. The reactor was pressurized at 280℃ and 4.5MPa for 30 minutes. During this pressurization period, ultrasonic assistance was initiated, with a controlled frequency of 80kHz and a power density of 1.0W / cm³. 3 After the pressure maintenance is completed, a step-by-step depressurization is carried out, that is, eight depressurizations are completed within 10 seconds, each depressurization pressure is 30% of the previous pressure, and the pressure is held for 0.1 seconds after each depressurization, and finally completely depressurized to atmospheric pressure (the pressure mentioned is gauge pressure, that is, the gauge pressure of atmospheric pressure is 0). After drying, the explosive product is obtained.

[0072] 3. Simultaneous carbonization and activation

[0073] The explosive material was placed in a pyrolysis furnace and carbonized under an argon atmosphere by programmed temperature increase. The temperature was increased to 700℃ at 5℃ / min and held for 30min to fully decompose and create pores in the second carbon precursor. Then, the temperature was increased to 1200℃ at 10℃ / min and held for 3h to fully graphitize the first carbon precursor and achieve in-situ self-activation. After cooling, a silicon-carbon composite material was obtained.

[0074] Comparative Example 1

[0075] Based on Example 1, the following changes were made:

[0076] 1. Ball mill

[0077] Mix 18g of silica powder with 18g of high-temperature asphalt, stir evenly, and then ball mill for 10 hours. The ball-to-material ratio is 4:1 and the ball milling speed is 140 rpm. After ball milling, mix the powder.

[0078] The silicon powder has a particle size of 2.5 μm;

[0079] The high-temperature asphalt has a softening point of 90℃, an ash content of 0.1wt%, a quinoline insoluble content of 7wt%, and a particle size of 70μm.

[0080] 2. Simultaneous carbonization and activation

[0081] The mixed powder was subjected to simultaneous carbonization and activation steps, which were performed in exactly the same manner as in Example 1.

[0082] Comparative Example 2

[0083] Based on Example 1, the following changes were made:

[0084] 1. Preparation of precursor composite slurry

[0085] 18g of silicon powder was added to 36g of 78wt% ethanol solution and stirred at 200rpm for 13min. Then, 36g of carbon precursor solution was added at a rate of 1.0g / min while stirring at 200rpm. After the addition was completed, stirring was continued for 37min to obtain the precursor composite slurry.

[0086] The silicon powder has a particle size of 2.5 μm;

[0087] The carbon precursor solution was prepared by adding 18g of high-temperature asphalt to 18g of 78wt% ethanol solution and stirring at 200rpm for 8min.

[0088] The high-temperature asphalt has a softening point of 90℃, an ash content of 0.1wt%, a quinoline insoluble content of 7wt%, and a particle size of 70μm.

[0089] 2. Steam explosion

[0090] The precursor composite slurry was pumped into a steam explosion reactor, saturated steam was introduced, and the pressure was maintained at 240℃ and 3.5MPa for 35 minutes. After the pressure maintenance was completed, the pressure was instantly released to atmospheric pressure (the pressure is gauge pressure, i.e., the gauge pressure of atmospheric pressure is 0). After drying, the explosion product was obtained.

[0091] 3. Simultaneous carbonization and activation

[0092] The explosive material was subjected to simultaneous carbonization and activation steps, which were performed in exactly the same manner as in Example 1.

[0093] Applications in electrochemistry

[0094] The silicon-carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-2 were used to prepare electrode sheets with 10 wt% conductive carbon black and 10 wt% polyacrylic acid coagulant. The lithium sheet was used as the counter electrode, and CR2032 coin cells were assembled. The electrolyte was 1M LiPF6 in EC / DEC (1:1) with 10% FEC, where 1:1 is the volume ratio. The electrochemical performance of the cells in Examples 1-3 and Comparative Examples 1-2 was tested.

[0095] 1. Cyclic performance

[0096] The batteries prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to cycle performance tests at a current density of 0.5C (1C=2000mA / g). The test results are as follows:

[0097]

[0098] It is evident that the reversible capacity of Comparative Examples 1-2 is low in the first cycle and has a low capacity retention rate after 500 cycles, indicating poor cycling performance.

[0099] 2. Ratio Performance

[0100] The batteries prepared in Examples 1-2 and Comparative Examples 1-2 were tested for discharge capacity (mAh / g) at 0.2C, 0.5C, 1C, 2C, and 5C respectively. The test results are as follows:

[0101]

[0102] It can be seen that the discharge capacity retention rate of Comparative Examples 1-2 is low with the increase of current density, and the capacity is significantly different from the initial value when it recovers to a low rate of 0.2C, indicating that the rate performance and material stability of the comparative examples are poor.

[0103] According to the data in the table above, Comparative Example 1 only uses ball milling to mix asphalt and silicon powder. The interfacial bonding is weak, there is a lot of interfacial contact resistance, the electron transport efficiency is low, and the volume expansion of silicon cannot be effectively buffered. During the charging and discharging process, the silicon particles repeatedly expand and contract, causing the carbon layer to crack, the active material to pulverize, the transport path to be interrupted, and ultimately the capacity decay. The volume effect is more severe at high rates, and the capacity cannot be recovered when the current returns to a low rate.

[0104] Comparative Example 2 uses a slurry method combined with steam explosion treatment and high-temperature asphalt as a single carbon source. It lacks the pore-forming and interface modification of sodium lignosulfonate, which cannot adequately buffer the volume expansion of silicon. After carbonization with a single carbon source, the interfacial bonding force between the carbon layer and silicon particles is weak, which accelerates the capacity decay. In addition, the traditional single steam explosion produces large and unevenly distributed pores, resulting in weak rate performance. However, compared with Comparative Example 1, the distribution of silicon particles and carbon materials is relatively uniform, and the cycle performance and rate performance are relatively better than those of Comparative Example 1.

[0105] Unless otherwise specified, all proportions mentioned in this invention are mass proportions, and all percentages are mass percentages.

[0106] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing silicon-carbon composite materials based on steam explosion, characterized in that, This includes steps such as preparation of precursor composite slurry, steam explosion, simultaneous carbonization and activation; The method for preparing the precursor composite slurry is as follows: silicon powder is added to an ethanol solution and stirred evenly; carbon precursor solution is added and stirring is continued for 35-40 minutes to obtain the precursor composite slurry. The carbon precursor solution is prepared by adding a first carbon precursor and a second carbon precursor to an ethanol solution and stirring at 180-200 rpm for 5-10 min. The first carbon precursor is one of high-temperature asphalt and phenolic resin; The second carbon precursor is one of sodium lignosulfonate, chitosan, and corn starch; The mass ratio of the first carbon precursor to the second carbon precursor is 0.5-2:1; The mass ratio of silicon powder to total carbon precursor is 0.25-2:1; The total carbon precursor is the sum of the first carbon precursor and the second carbon precursor; The steam explosion treatment step involves pumping the precursor composite slurry into a steam explosion reactor, introducing saturated steam, and maintaining pressure at 200-280℃ and 2.0-4.5MPa for 30-40 minutes. During this pressure maintenance, ultrasonic assistance is activated at a frequency of 40-80kHz and a power density of 0.3-1.0W / cm³. 3 After the pressure maintenance is completed, a step-by-step depressurization is carried out, that is, 3-8 depressurizations are completed within 6-10 seconds, each depressurization pressure is 10-30% of the previous pressure, and the pressure is held for 0.1-0.2 seconds after each depressurization, and finally completely depressurized to atmospheric pressure. After drying, the explosive product is obtained. The simultaneous carbonization and activation steps are as follows: the explosive material is put into a pyrolysis furnace, and carbonization is carried out by programmed temperature increase under an argon atmosphere. The temperature is increased at 2-5℃ / min to 500-700℃ and held for 10-30 min to fully decompose and create pores in the second carbon precursor. Then, the temperature is increased at 5-10℃ / min to 900-1200℃ and held for 1-3 h to fully graphitize the first carbon precursor and achieve in-situ self-activation. After cooling, the silicon-carbon composite material is obtained.

2. The method for preparing a silicon-carbon composite material based on steam explosion according to claim 1, characterized in that, In the carbon precursor solution, the mass concentration of the ethanol solution is 74-78%. The mass ratio of the ethanol solution to the total carbon precursor is 1:

1.

3. The method for preparing a silicon-carbon composite material based on steam explosion according to claim 1, characterized in that, In the preparation method of the precursor composite slurry, the particle size of the silicon powder is 0.5-5μm; The mass ratio of silicon powder to ethanol solution is 15-20:7.5-320; The particle size of the first carbon precursor is 50-80 μm; The high-temperature asphalt has a softening point of 85-95℃, an ash content of 0.1-0.2wt%, and a quinoline-insoluble content of 6-8wt%. The molecular weight of the phenolic resin is 800-1500; The chitosan and corn starch have a particle size of 120-150 mesh.

4. A silicon-carbon composite material based on steam explosion, characterized in that, Prepared by the preparation method according to any one of claims 1-3.

5. An application of a silicon-carbon composite material based on steam explosion, characterized in that, The steam explosion-based silicon-carbon composite material is prepared by the preparation method according to any one of claims 1-3.

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