System and process method capable of continuously preparing high-gram-volume and low-expansion silicon-carbon material

Abstract

The invention discloses a system and a process method capable of continuously preparing a high-gram-volume and low-expansion silicon-carbon material, and belongs to the technical field of lithium ion battery negative electrode material preparation, the system comprises a raw material bin, a preheating zone A, a multi-stage silicon deposition reactor, a preheating zone B, a multi-stage carbon coating reactor and a gas-solid separation device which are communicated in sequence; the preheating zone A, the multi-stage silicon deposition reactor, the preheating zone B and the multi-stage carbon coating reactor are all communicated with a nitrogen main air duct through nitrogen branch air ducts; the multi-stage silicon deposition reactor is communicated with the silane gas main air duct through a plurality of silane gas branch air ducts, and the multi-stage carbon coating reactor is communicated with the acetylene gas main air duct through a plurality of acetylene gas branch air ducts. The large-scale continuous production of the silicon-carbon material with high gram volume and low expansion rate can be realized, the uniformity of silicon deposition and carbon coating is good, the production efficiency can be improved, the energy consumption can be reduced, the manufacturing cost of the silicon-carbon material can be reduced, and the product yield can also be improved.

Description

Technical Field

[0001] The present invention relates to a system and process method for continuously preparing high specific capacity and low expansion silicon-carbon materials, belonging to the technical field of preparation of anode materials for lithium-ion batteries. Background Art

[0002] With the rapid development of emerging industries such as new energy vehicles, humanoid robots, and evtol, higher requirements are put forward for the energy density, safety performance, cycle performance, etc. of lithium-ion batteries. For traditional graphite anode materials, the theoretical specific capacity limit is only 372 mAh / g, while for silicon anode materials it is 4200 mAh / g, which is much higher than that of graphite. However, the volume expansion rate of silicon materials is as high as 300%, restricting its practical application.

[0003] Currently, domestic and foreign anode material manufacturers mostly use equipment such as fixed reactors, rotary kilns, and fluidized beds, and utilize the principle of chemical vapor deposition to achieve the deposition of nano-silicon particles at the pores of porous carbon, with carbon coating on the outer layer. With the elastic buffering of the porous carbon matrix and the outer carbon layer, the performance of silicon anode materials is greatly improved, with a specific capacity of up to 1800 mAh / g and a cycle life close to 1500 times. However, there are still the following technical problems in the process of producing silicon-carbon materials by equipment such as fixed reactors, rotary kilns, and fluidized beds; There are problems of uneven silicon deposition and carbon coating. The above three methods can only achieve batch continuous production and cannot achieve true continuous feeding and continuous discharging operations. For example, currently, the rotary kiln can only discharge 100 - 300 kg per batch, and the fluidized bed can only process 50 - 100 kg per batch, with low production efficiency; It is necessary to frequently and intermittently raise and lower the temperature significantly, which will have an important impact on the service life of key components of the equipment and also cause energy waste; The sharing of labor, factory buildings, equipment, etc. will all increase; resulting in a relatively high cost of silicon-carbon materials and being not conducive to large-scale popularization and application.

[0004] Therefore, there is an urgent need to provide a system and process method for continuously preparing high specific capacity and low expansion silicon-carbon materials to solve the above problems. Summary of the Invention

[0005] Aiming at the deficiencies in the background art, the present invention provides a system and process method for continuously preparing high specific capacity and low expansion silicon-carbon materials, which can achieve large-scale continuous production of high specific capacity and low expansion rate silicon-carbon materials, with good uniformity of silicon deposition and carbon coating. It can not only improve production efficiency, reduce energy consumption, lower the manufacturing cost of silicon-carbon materials, but also improve the product yield.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: A system for continuously preparing high specific capacity and low expansion silicon-carbon materials, comprising a raw material bin, a preheating zone A, a multi-stage silicon precipitation reactor, a preheating zone B, a multi-stage carbon coating reactor, and a gas-solid separation device connected in sequence; the preheating zone A, the multi-stage silicon precipitation reactor, the preheating zone B, and the multi-stage carbon coating reactor are all connected to a nitrogen main duct through nitrogen branch ducts, and a nitrogen blower is installed on the nitrogen main duct; the multi-stage silicon precipitation reactor is connected to a silane gas main duct through a plurality of silane gas branch ducts, and the silane gas branch ducts are arranged in one-to-one correspondence with the reaction zones in the multi-stage silicon precipitation reactor, and a silane gas blower is installed on the silane gas main duct; the multi-stage carbon coating reactor is connected to an acetylene gas main duct through a plurality of acetylene gas branch ducts, and the acetylene gas branch ducts are arranged in one-to-one correspondence with the reaction zones in the multi-stage carbon coating reactor, and an acetylene gas blower is installed on the acetylene gas main duct.

[0007] Further, a vibrator is installed between the discharge port of the raw material bin and the feed port of the preheating zone A; both the multi-stage silicon precipitation reactor and the multi-stage carbon coating reactor are arranged horizontally, and a breathable valve A is installed between the feed port of the multi-stage silicon precipitation reactor and the discharge port of the preheating zone A, a breathable valve B is installed between the discharge port of the multi-stage silicon precipitation reactor and the feed port of the preheating zone B, a breathable valve C is installed between the discharge port of the preheating zone B and the feed port of the multi-stage carbon coating reactor, and a breathable valve D is installed between the discharge port of the multi-stage carbon coating reactor and the feed port of the gas-solid separation device.

[0008] Further, the multi-stage silicon precipitation reactor is internally provided with 2 to 8 reaction zones, and a movable microporous baffle A is provided between adjacent reaction zones, and the movable microporous baffle A can be intermittently opened and closed; The multi-stage carbon coating reactor is internally provided with 2 to 4 reaction zones, and a movable microporous baffle B is provided between adjacent reaction zones, and the movable microporous baffle B can be intermittently opened and closed.

[0009] Further, a fine powder recovery device is installed above the multi-stage silicon precipitation reactor near its outlet end, and the fine powder recovery device is connected to the preheating zone A through a reflux pipe.

[0010] Further, the discharge port of the gas-solid separation device is respectively connected to a tail gas treatment device and a finished product bin, and a cooling device is arranged around the finished product bin.

[0011] A process method for continuously preparing high specific capacity and low expansion silicon-carbon materials, applying the above system, comprising the following steps: Step 1: The porous carbon powder enters the vibrator from the raw material bin and is then transported to the preheating zone A. After maintaining a certain temperature for a period of time, the air-permeable valve A is opened. After purging with nitrogen, the porous carbon powder in the preheating zone A enters the first reaction zone of the multi-stage silicon deposition reactor. The multi-stage silicon deposition reactor has been heated to the set temperature. The porous carbon powder is fluidized by the mixture of nitrogen and silane. After silane cracking for a certain period of time, the movable microporous baffle A between the first reaction zone and the second reaction zone is opened, and the powder enters the second reaction zone. The ratio of silane to nitrogen in the mixture is adjusted through the gas flowmeter. After silane cracking for a certain period of time, the movable microporous baffle A between the second reaction zone and the third reaction zone is opened, and the powder enters the third reaction zone. The ratio of silane to nitrogen in the mixture is adjusted through the gas flowmeter. By analogy, the powder enters each reaction zone; Step 2: After the reaction in the multi-stage silicon deposition reactor is completed, the air-permeable valve B is opened, and the powder enters the preheating zone B. The preheating zone B has been heated to the set temperature. Continuous purging with nitrogen is carried out. After maintaining a certain temperature for a period of time, the air-permeable valve C is opened, and the powder enters the first reaction zone of the multi-stage carbon coating reactor; Step 3: The multi-stage carbon coating reactor has been heated to the set temperature. The material powder is fluidized by the mixture of nitrogen and acetylene. After acetylene cracking for a certain period of time, the movable microporous baffle B between the first reaction zone and the second reaction zone is opened, and the powder enters the second reaction zone. The ratio of acetylene to nitrogen in the mixture is adjusted through the gas flowmeter. After acetylene cracking for a certain period of time, the movable microporous baffle B between the second reaction zone and the third reaction zone is opened, and the powder enters the third reaction zone. The ratio of acetylene to nitrogen in the mixture is adjusted through the gas flowmeter. By analogy, the powder enters each reaction zone; Step 4: After the reaction in the multi-stage carbon coating reactor is completed, the air-permeable valve D is opened, and the material enters the gas-solid separation device for separation. The silicon-carbon material enters the finished product bin and is cooled by the cooling device. The generated tail gas enters the tail gas treatment device.

[0012] Further, the porous carbon powder material is resin-based, biomass-based or coal-based, and the particle size is 1 - 15 μm.

[0013] Further, the temperature of the preheating zone A is 450 - 500 °C, and the heat preservation time is 10 - 60 min; the temperature of the preheating zone B is 550 - 650 °C, and the heat preservation time is 10 - 60 min.

[0014] Further, the temperature of the multi-stage silicon deposition reactor is 450 - 500 °C, the total silicon deposition reaction time is 2 - 10 h, the shape of the reaction cavity of the multi-stage silicon deposition reactor is circular, and the diameter is 200 - 1000 mm.

[0015] Further, the temperature inside the multi-stage carbon-coated reactor is 550 - 650 °C, the total carbon coating time is 2 - 8 h, the shape of the reaction chamber of the multi-stage carbon-coated reactor is circular, and the diameter is 400 - 2000 mm.

[0016] After the present invention adopts the above technical solutions, compared with traditional fixed reactors, rotary kilns, fluidized beds and other technologies, the present invention has the following advantages: 1. It can realize the large-scale continuous production of silicon-carbon materials, with high production efficiency, reduced energy consumption, and reduced manufacturing cost of silicon-carbon materials.

[0017] 2. The product yield is high, the silicon deposition and carbon coating are more uniform, and the prepared silicon-carbon materials have the characteristics of high specific capacity and low expansion rate.

[0018] 3. It reduces the frequent heating and cooling of equipment, extends the service life of equipment, improves the utilization rate of equipment, and reduces the comprehensive cost.

[0019] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of a system for continuously preparing silicon-carbon materials with high specific capacity and low expansion; Figure 2 is a summary diagram of the performance and estimated annual production capacity of the silicon-carbon materials prepared in Examples 1 - 4.

[0021] In the figure, 1 - raw material bin, 2 - vibrator, 3 - preheating zone A, 4 - multi-stage silicon deposition reactor, 5 - fine powder recovery device, 6 - movable microporous baffle A, 7 - preheating zone B, 8 - multi-stage carbon-coated reactor, 9 - movable microporous baffle B, 10 - silane gas blower, 11 - nitrogen blower, 12 - acetylene gas blower, 13 - main silane gas duct, 14 - main nitrogen duct, 15 - main acetylene gas duct, 16 - silane gas branch duct, 17 - nitrogen branch duct, 18 - acetylene gas branch duct, 19 - gas-solid separation device, 20 - tail gas treatment device, 21 - finished product bin, 22 - cooling device, 23 - return pipe, 24 - air permeable valve A, 25 - air permeable valve B, 26 - air permeable valve C, 27 - air permeable valve D. Detailed Embodiments

[0022] For a clearer understanding of the technical features, objectives and effects of the present invention, the specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0023] As Figure 1As shown in the figure, the present invention provides a system for continuously preparing a high specific capacity and low expansion silicon-carbon material, which includes a raw material bin 1, a preheating zone A3, a multi-stage silicon precipitation reactor 4, a preheating zone B7, a multi-stage carbon coating reactor 8, and a gas-solid separation device 19 that are connected in sequence.

[0024] The preheating zone A3, the multi-stage silicon precipitation reactor 4, the preheating zone B7, and the multi-stage carbon coating reactor 8 are all connected to the nitrogen main duct 14 through nitrogen branch ducts 17, and a nitrogen blower 11 is installed on the nitrogen main duct 14.

[0025] The multi-stage silicon precipitation reactor 4 is connected to the silane gas main duct 13 through a plurality of silane gas branch ducts 16. The silane gas branch ducts 16 are arranged in one-to-one correspondence with the reaction zones in the multi-stage silicon precipitation reactor 4, and a silane gas blower 10 is installed on the silane gas main duct 13.

[0026] The multi-stage carbon coating reactor 8 is connected to the acetylene gas main duct 15 through a plurality of acetylene gas branch ducts 18. The acetylene gas branch ducts 18 are arranged in one-to-one correspondence with the reaction zones in the multi-stage carbon coating reactor 8, and an acetylene gas blower 12 is installed on the acetylene gas main duct 15.

[0027] Gas flow meters are installed on the ducts for transporting silane gas, nitrogen, and acetylene gas.

[0028] A vibrator 2 is installed between the discharge port of the raw material bin 1 and the feed port of the preheating zone A3. The vibrator 2 vibrates and conveys the porous carbon powder in the raw material bin 1 into the preheating zone A3.

[0029] The multi-stage silicon precipitation reactor 4 and the multi-stage carbon coating reactor 8 are both arranged horizontally. An air-permeable valve A24 is installed between the feed port of the multi-stage silicon precipitation reactor 4 and the discharge port of the preheating zone A3. An air-permeable valve B25 is installed between the discharge port of the multi-stage silicon precipitation reactor 4 and the feed port of the preheating zone B7. An air-permeable valve C26 is installed between the discharge port of the preheating zone B7 and the feed port of the multi-stage carbon coating reactor 8. An air-permeable valve D27 is installed between the discharge port of the multi-stage carbon coating reactor 8 and the feed port of the gas-solid separation device 19.

[0030] The multi-stage silicon precipitation reactor 4 is internally provided with a plurality of reaction zones. An active microporous baffle A6 is provided between adjacent reaction zones. The active microporous baffle A6 divides the reaction regions in the multi-stage silicon precipitation reactor 4, and the active microporous baffle A6 can be intermittently opened and closed to ensure the smooth flow of materials in each reaction zone.

[0031] In the multi-stage silicon precipitation reactor 4, its internal area can be divided into two-stage, three-stage, four-stage, five-stage, six-stage, seven-stage, or eight-stage reaction zones according to raw material properties, finished product performance requirements, etc.

[0032] The multi-stage carbon-coated reactor 8 is internally provided with a plurality of reaction zones, and a movable microporous baffle B9 is arranged between adjacent reaction zones. The movable microporous baffle B9 divides the reaction zones in the multi-stage carbon-coated reactor 8, and the movable microporous baffle B9 can be intermittently opened and closed to ensure the smooth flow of materials in each reaction zone.

[0033] In the multi-stage carbon-coated reactor 8, its internal area can be divided into secondary, tertiary or quaternary reaction zones according to the properties of raw materials, the requirements of product performance, etc.

[0034] Both the movable microporous baffle A6 and the movable microporous baffle B9 are composed of upper and lower parts, and the upper and lower parts can be folded respectively. When not folded, it is in a closed state and gas can pass through normally; when folded, it is in an open state and gas and powder can pass through normally.

[0035] A fine powder recovery device 5 is installed above the outlet end of the multi-stage silicon deposition reactor 4. The fine powder recovery device 5 is connected to the preheating zone A3 through a reflux pipe 23. The fine powder recovery device 5 can recover the porous carbon materials with less deposited silicon and less deposited silicon amount, and transmit them back to the preheating zone A3 through the reflux pipe 23 to improve the powder yield.

[0036] The discharge ports of the gas-solid separation device 19 are respectively connected to the tail gas treatment device 20 and the finished product silo 21, and a cooling device 22 is arranged outside the finished product silo 21.

[0037] A process method for preparing a high specific capacity and low expansion silicon-carbon material by using the above system includes the following steps: Step 1: The porous carbon powder enters the vibrator 2 from the raw material bin 1 and is then transported to the preheating zone A3. After maintaining a certain temperature for a certain time, the air permeable valve A24 is opened, and after purging with nitrogen, the porous carbon powder in the preheating zone A3 enters the first reaction zone of the multi-stage silicon deposition reactor 4. The multi-stage silicon deposition reactor 4 has been heated to the set temperature, and the porous carbon powder is fluidized by the mixed gas of nitrogen and silane. After silane is cracked for a certain time, the movable microporous baffle A6 between the first reaction zone and the second reaction zone is opened, and the powder enters the second reaction zone. The ratio of silane and nitrogen in the mixed gas is adjusted by the gas flow meter. After silane is cracked for a certain time, the movable microporous baffle A6 between the second reaction zone and the third reaction zone is opened, and the powder enters the third reaction zone. The ratio of silane and nitrogen in the mixed gas is adjusted by the gas flow meter, and so on, and the powder enters each reaction zone; Step 2: After the reaction in the multi-stage silicon deposition reactor 4 is completed, the air permeable valve B25 is opened, and the powder enters the preheating zone B7. The preheating zone B7 has been heated to the set temperature, and continuous purging with nitrogen is carried out. After maintaining a certain temperature for a certain time, the air permeable valve C26 is opened, and the powder enters the first reaction zone of the multi-stage carbon-coated reactor 8; Step 3: The multi-stage carbon-coated reactor 8 has been heated to the set temperature. The material powder is fluidized by the mixed gas of nitrogen and acetylene. After acetylene is pyrolyzed for a certain time, the movable microporous baffle B9 between the first reaction zone and the second reaction zone is opened, and the powder enters the second reaction zone. The ratio of acetylene to nitrogen in the mixed gas is adjusted by the gas flowmeter. After acetylene is pyrolyzed for a certain time, the movable microporous baffle B9 between the second reaction zone and the third reaction zone is opened, and the powder enters the third reaction zone. The ratio of acetylene to nitrogen in the mixed gas is adjusted by the gas flowmeter, and so on. The powder enters each reaction zone; Step 4: After the reaction in the multi-stage carbon-coated reactor 8 is completed, the air-permeable valve D27 is opened, and the material enters the gas-solid separation device 19 for separation. The silicon-carbon material enters the finished product bin 21 and is cooled by the cooling device 22. The generated tail gas enters the tail gas treatment device 20.

[0038] In the present invention, the porous carbon material is resin-based, biomass-based or coal-based, and the particle size is 1-15 μm.

[0039] In the present invention, the temperature of the preheating zone A3 is 450-500 °C, and the heat preservation time is 10-60 min.

[0040] In the present invention, the temperature of the multi-stage silicon deposition reactor 4 is 450-500 °C, and the total silicon deposition reaction time is 2-10 h.

[0041] In the present invention, the shape of the reaction cavity of the multi-stage silicon deposition reactor 4 can be circular or square, preferably circular, and the diameter is 200-1000 mm.

[0042] In the present invention, the temperature of the preheating zone B7 is 550-650 °C, and the heat preservation time is 10-60 min.

[0043] In the present invention, the temperature in the multi-stage carbon-coated reactor 8 is 550-650 °C, and the total carbon coating time is 2-8 h.

[0044] In the present invention, the shape of the reaction cavity of the multi-stage carbon-coated reactor 8 can be circular or square, preferably circular, and the diameter is 400-2000 mm.

[0045] Example 1 A system for continuously preparing a high specific capacity and low expansion silicon-carbon material, equipment parameters: the inner cavity of the multi-stage silicon deposition reactor is circular, with a diameter of 200 mm, and is divided into four reaction zones; the inner cavity of the carbon-coated reactor is circular, with a diameter of 400 mm, and is divided into two reaction zones.

[0046] This example also provides a process method for preparing a high specific capacity and low expansion silicon-carbon material by using the aforementioned system, specifically: Step 1: The biomass-based porous carbon powder with a D50 particle size of 8 μm enters the preheating zone A via the raw material bin and then enters the vibrator. After being kept at 480 °C for 10 min, the air-permeable valve A is opened. After purging with nitrogen, the porous carbon powder in the preheating zone A enters the first reaction zone of the multi-stage silicon deposition reactor. The multi-stage silicon deposition reactor has been heated to 480 °C. The porous carbon powder is fluidized by the mixture of nitrogen and silane. After 30 min of silane cracking, the movable microporous baffle A between the first reaction zone and the second reaction zone is opened, and the powder enters the second reaction zone. The ratio of silane to nitrogen in the mixture is adjusted by the gas flowmeter. After 30 min of silane cracking, the movable microporous baffle A between the second reaction zone and the third reaction zone is opened, and the powder enters the third reaction zone. The ratio of silane to nitrogen in the mixture is adjusted by the gas flowmeter. After 30 min of silane cracking, the movable microporous baffle A between the third reaction zone and the fourth reaction zone is opened, and the ratio of silane to nitrogen in the mixture is adjusted by the gas flowmeter. After 30 min of silane cracking; Step 2: After the reaction in the multi-stage silicon deposition reactor ends, the air-permeable valve B is opened, and the powder enters the preheating zone B. The preheating zone B has been heated to 570 °C. Nitrogen purging is continuously carried out. After 20 min of heat preservation, the air-permeable valve C is opened, and the powder enters the first reaction zone of the multi-stage carbon coating reactor; Step 3: The multi-stage carbon coating reactor has been heated to 570 °C. The material powder is fluidized by the mixture of nitrogen and acetylene. After 60 min of acetylene cracking, the movable microporous baffle B between the first reaction zone and the second reaction zone is opened, and the powder enters the second reaction zone. The ratio of acetylene to nitrogen in the mixture is adjusted by the gas flowmeter. Acetylene cracking is carried out for 60 min; Step 4: After the reaction in the multi-stage carbon coating reactor ends, the air-permeable valve D is opened. The material is separated in the gas-solid separation device. The silicon-carbon material enters the finished product bin and is cooled by the cooling device. The generated tail gas enters the tail gas treatment device.

[0047] When continuous production is formed, the movable microporous baffle A in the multi-stage silicon deposition reactor and the movable microporous baffle B in the multi-stage carbon coating reactor will be intermittently opened and closed to ensure the smooth flow of materials in the reaction zone.

[0048] The performance and annual production capacity estimation of the silicon-carbon material prepared by this system are summarized in Figure 2 as shown.

[0049] Example 2 A system for continuously preparing high specific capacity and low expansion silicon-carbon materials, equipment parameters: the inner cavity of the multi-stage silicon deposition reactor is circular with a diameter of 1000 mm and is divided into eight reaction zones; the inner cavity of the carbon coating reactor is circular with a diameter of 2000 mm and is divided into four reaction zones.

[0050] This embodiment also provides a process method for preparing a high specific capacity and low expansion silicon-carbon material by using the aforementioned system. The specific process parameters are as follows: The porous carbon material is resin-based, the D50 particle size is 4 μm, the temperature of preheating zone A is 500 °C, and the heat preservation time is 60 min; the temperature of the multi-stage silicon deposition reactor is 500 °C, and the fluidization time for each reaction zone is 70 min; the temperature of preheating zone B is 620 °C, and the heat preservation time is 60 min; the temperature in the multi-stage carbon coating reactor is 620 °C, and the carbon coating time for each reaction zone is 120 min.

[0051] The performance and annual production capacity estimation of the silicon-carbon material prepared by this system are summarized in Figure 2 as shown in.

[0052] Example 3 A system for continuously preparing a high specific capacity and low expansion silicon-carbon material, with equipment parameters: The inner cavity of the multi-stage silicon deposition reactor is circular, with a diameter of 500 mm, and is divided into six reaction zones; the inner cavity of the carbon coating reactor is circular, with a diameter of 1000 mm, and is divided into three reaction zones.

[0053] This embodiment also provides a process method for preparing a high specific capacity and low expansion silicon-carbon material by using the aforementioned system. The specific process parameters are as follows: The porous carbon material is coal-based, the D50 particle size is 10 μm, the temperature of preheating zone A is 480 °C, and the heat preservation time is 40 min; the temperature of the multi-stage silicon deposition reactor is 480 °C, and the fluidization time for each reaction zone is 75 min; the temperature of preheating zone B is 590 °C, and the heat preservation time is 40 min; the temperature in the multi-stage carbon coating reactor is 590 °C, and the carbon coating time for each reaction zone is 75 min.

[0054] The performance and annual production capacity estimation of the silicon-carbon material prepared by this system are summarized in Figure 2 as shown in.

[0055] Example 4 A system for continuously preparing a high specific capacity and low expansion silicon-carbon material, with equipment parameters: The inner cavity of the multi-stage silicon deposition reactor is circular, with a diameter of 1000 mm, and is divided into eight reaction zones; the inner cavity of the carbon coating reactor is circular, with a diameter of 2000 mm, and is divided into four reaction zones.

[0056] This embodiment also provides a process method for preparing a high specific capacity and low expansion silicon-carbon material by using the aforementioned system. The specific process parameters are as follows: Experimental parameters: The porous carbon material is resin-based, with a D50 particle size of 2 μm, the temperature of preheating zone A is 490 °C, and the holding time is 60 min; the temperature of the multi-stage silicon deposition reactor is 490 °C, and the fluidization time for each reaction zone is 70 min; the temperature of preheating zone B is 600 °C, and the holding time is 60 min; the temperature of the multi-stage carbon coating reactor is 600 °C, and the carbon coating time for each reaction zone is 80 min.

[0057] The performance and annual production capacity estimation of the silicon-carbon material prepared by this system are summarized in Figure 2 as shown.

[0058] The above are examples of the best implementation modes of the present invention. Those parts not described in detail are common general knowledge of those skilled in the art. The protection scope of the present invention is subject to the content of the claims, and any equivalent transformation based on the technical inspiration of the present invention is also within the protection scope of the present invention.

Claims

1. A system for continuously preparing high gram capacity, low expansion silicon-carbon materials, characterized in that: It comprises a raw material bin (1), a preheating zone A (3), a multi-stage silicon precipitation reactor (4), a preheating zone B (7), a multi-stage carbon coating reactor (8) and a gas-solid separation device (19) which are sequentially connected and arranged; The preheating zone A (3), the multi-stage silicon precipitation reactor (4), the preheating zone B (7) and the multi-stage carbon coating reactor (8) are all connected to the nitrogen main air duct (14) through a nitrogen branch air duct (17), and a nitrogen blower (11) is installed on the nitrogen main air duct (14); The multi-stage silicon deposition reactor (4) is connected to the silane gas main air duct (13) via a plurality of silane gas branch air ducts (16); the silane gas branch air ducts (16) are arranged in one-to-one correspondence with the reaction zones in the multi-stage silicon deposition reactor (4); and a silane gas blower (10) is installed on the silane gas main air duct (13); The multi-stage carbon-coated reactor (8) is connected to the acetylene gas main air duct (15) via a plurality of acetylene gas branch air ducts (18); the acetylene gas branch air ducts (18) are arranged in one-to-one correspondence with the reaction zones in the multi-stage carbon-coated reactor (8); and an acetylene gas blower (12) is installed on the acetylene gas main air duct (15).

2. A system for continuously preparing high gram capacity, low expansion silicon-carbon materials as claimed in claim 1, characterized in that: A vibrator (2) is installed between the discharge port of the raw material bin (1) and the feed port of the preheating zone A (3); a breathable valve A (24) is installed between the feed port of the multi-stage silicon precipitation reactor (4) and the discharge port of the preheating zone A (3); a breathable valve B (25) is installed between the discharge port of the multi-stage silicon precipitation reactor (4) and the feed port of the preheating zone B (7); a breathable valve C (26) is installed between the discharge port of the preheating zone B (7) and the feed port of the multi-stage carbon coating reactor (8); and a breathable valve D (27) is installed between the discharge port of the multi-stage carbon coating reactor (8) and the feed port of the gas-solid separation device (19).

3. A system for continuously preparing high gram capacity, low expansion silicon-carbon materials as claimed in claim 1, characterized in that: The multi-stage silicon precipitation reactor (4) is provided with 2 to 8 reaction zones, and a movable microporous baffle A (6) is provided between adjacent reaction zones, and the movable microporous baffle A (6) can be opened and closed intermittently; The multi-stage carbon coating reactor (8) is provided with 2 to 4 reaction zones inside, and a movable microporous baffle B (9) is provided between adjacent reaction zones. The movable microporous baffle B (9) can be opened and closed intermittently.

4. A system for continuously preparing high gram capacity, low expansion silicon-carbon materials as claimed in claim 1, characterized in that: A fine powder recovery device (5) is installed above the multi-stage silicon precipitation reactor (4) near its outlet end, and the fine powder recovery device (5) is connected to the preheating zone A (3) via a reflux pipe (23).

5. A system for continuously preparing high gram capacity, low expansion silicon-carbon materials as claimed in claim 1, characterized in that: The discharge port of the gas-solid separation device (19) is respectively connected to the tail gas treatment device (20) and the finished product silo (21), and a cooling device (22) is arranged outside the finished product silo (21).

6. A process for continuously preparing high gram capacity and low expansion silicon-carbon materials, using the system for continuously preparing high gram capacity and low expansion silicon-carbon materials as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, porous carbon powder enters the vibrator (2) through the raw material bin (1) and is then transported to the preheating zone A (3). After being kept warm for a certain period of time, the air permeable valve A (24) is opened, and the porous carbon powder in the preheating zone A (3) is purged with nitrogen to enter the primary reaction zone of the multi-stage silicon precipitation reactor (4). The multi-stage silicon precipitation reactor (4) has been heated to a set temperature, and the porous carbon powder is fluidized by a nitrogen and silane mixture. After silane is cracked for a certain period of time, the movable microporous baffle A (6) between the primary reaction zone and the secondary reaction zone is opened, and the powder enters the secondary reaction zone. The ratio of silane to nitrogen in the mixed gas is adjusted by a gas flow meter. After silane is cracked for a certain period of time, the movable microporous baffle A (6) between the secondary reaction zone and the tertiary reaction zone is opened, and the powder enters the tertiary reaction zone. The ratio of silane to nitrogen in the mixed gas is adjusted by a gas flow meter. By analogy, the powder enters each level of reaction zone; Step 2, after the reaction in the multi-stage silicon precipitation reactor (4) is completed, the air-permeable valve B (25) is opened, and the powder enters the preheating zone B (7). The preheating zone B (7) has been heated to a set temperature and is continuously purged with nitrogen. After a certain period of heat preservation, the air-permeable valve C (26) is opened, and the powder enters the primary reaction zone of the multi-stage carbon coating reactor (8); Step 3, the multi-stage carbon-coated reactor (8) has been heated to a set temperature, and the material powder is fluidized by a nitrogen and acetylene mixed gas. After the acetylene is cracked for a certain period of time, the movable microporous baffle B (9) between the primary reaction zone and the secondary reaction zone is opened, and the powder enters the secondary reaction zone. The ratio of acetylene to nitrogen in the mixed gas is adjusted by a gas flow meter. After the acetylene is cracked for a certain period of time, the movable microporous baffle B (9) between the secondary reaction zone and the tertiary reaction zone is opened, and the powder enters the tertiary reaction zone. The ratio of acetylene to nitrogen in the mixed gas is adjusted by a gas flow meter. Similarly, the powder enters each level of reaction zone; Step 4: After the reaction in the multi-stage carbon coating reactor (8) is completed, the air permeable valve D (27) is opened, the material enters the gas-solid separation device (19) for separation, the silicon-carbon material enters the finished product silo (21), and is cooled by the cooling device (22), and the generated tail gas enters the tail gas treatment device (20).

7. A process for continuously preparing high gram capacity and low expansion silicon-carbon material according to claim 6, characterized in that: The porous carbon powder material is resin-based, biomass-based or coal-based, and has a particle size of 1 to 15 μm.

8. A process for continuously preparing high gram capacity and low expansion silicon-carbon material according to claim 6, characterized in that: The temperature of the preheating zone A (3) is 450-500°C, and the holding time is 10-60 minutes; the temperature of the preheating zone B (7) is 550-650°C, and the holding time is 10-60 minutes.

9. A process for continuously preparing high gram capacity and low expansion silicon-carbon material according to claim 6, characterized in that: The temperature of the multi-stage silicon deposition reactor (4) is 450-500° C., the total silicon deposition reaction time is 2-10 hours, and the reaction chamber of the multi-stage silicon deposition reactor (4) is circular in shape with a diameter of 200-1000 mm.

10. A process for continuously preparing high gram capacity and low expansion silicon-carbon material according to claim 6, characterized in that: The temperature in the multi-stage carbon coating reactor (8) is 550-650° C., the total carbon coating time is 2-8 hours, and the reaction chamber of the multi-stage carbon coating reactor (8) is circular in shape with a diameter of 400-2000 mm.

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