A system and process method for continuously preparing high-first-efficiency silicon-carbon materials

Abstract

The present invention discloses a system and a process method for continuously preparing high-first-efficiency silicon-carbon materials, belonging to the technical field of preparing anode materials for lithium-ion batteries. The system includes 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 that are connected in sequence. A lithium source supply device is connected to the side of the preheating zone B. 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. A plurality of reaction zones divided by staggered baffles A are arranged inside the multi-stage silicon precipitation reactor, and each reaction zone is connected to the nitrogen main duct through a purge air duct A. A plurality of reaction zones divided by staggered baffles B are arranged inside the multi-stage carbon coating reactor, and each reaction zone is connected to the nitrogen main duct through a purge air duct B. The present invention can solve the technical problems of the current silicon-carbon materials being unable to be continuously produced, having high costs, and low first efficiency.

Description

Technical Field

[0001] The present invention relates to a system and a process method for continuously preparing high-first-efficiency silicon-carbon materials, and belongs to the technical field of preparing anode materials for lithium-ion batteries. Background Art

[0002] With the rapid rise of emerging industries such as new energy transportation, intelligent robots, and flying cars, lithium-ion batteries face more stringent technical requirements in terms of energy density, safety performance, and cycle life. The current mainstream graphite anode material is limited by the theoretical specific capacity of 372 mAh / g, while the silicon-based material with an ultra-high theoretical specific capacity of 4200 mAh / g is difficult to achieve commercial application due to the 300% volume expansion effect during the charge and discharge process.

[0003] The industry has made important breakthroughs through innovative processes at present: using chemical vapor deposition technology to accurately deposit nano-silicon particles inside a porous carbon matrix and constructing an outer carbon coating structure. This composite design of an elastic skeleton and a buffer layer has increased the specific capacity of the silicon-carbon anode to 1800 mAh / g, and the number of cycles has exceeded 1500 times. However, there are still significant bottlenecks in the existing production processes:

[0004] The mainstream production equipment for silicon-carbon materials is fixed-bed reactors, rotary kilns, fluidized beds, etc. The mainstream equipment generally has the process defect of uneven silicon deposition and carbon coating, and the mainstream equipment all adopts an intermittent batch production mode and cannot achieve true continuous operation. For example, the rotary kiln can only discharge 100 - 300 kg per batch at present, and the fluidized bed can only process 50 - 100 kg per batch. This discontinuous production brings multiple challenges:

[0005] Frequent process starts and stops cause the equipment to experience severe temperature fluctuations (in the range of 400 - 600 °C), seriously shortening the service life of key components; the repeated heating and cooling processes result in more than 40% of ineffective energy consumption; the low utilization rate of factory buildings and equipment increases the unit cost; frequent manual operation interventions restrict the improvement of production capacity.

[0006] The above-mentioned systematic factors lead to the high comprehensive cost of silicon-carbon materials, becoming the main obstacle restricting the large-scale application of the industry.

[0007] At present, the first efficiency of most silicon-carbon materials is relatively low, only at the level of 80 - 85%. While the first efficiency of lithium iron phosphate materials can reach more than 95%, and that of graphite materials can reach more than 92%. When silicon-carbon materials / graphite are used in combination with lithium iron phosphate, the first efficiency drops to 87% or even lower, which will seriously affect the value of lithium iron phosphate materials.

[0008] Therefore, there is an urgent need to provide a system and a process method for continuously preparing high-first-efficiency silicon-carbon materials to solve the above problems.

[0009] In summary, it is obvious that there are inconveniences and defects in the prior art during actual use, so it is necessary to make improvements. Summary of the Invention

[0010] Aiming at the deficiencies in the background technology, the present invention provides a system and process method for continuously preparing high-first-efficiency silicon-carbon materials, which can solve the technical problems that current silicon-carbon materials cannot be continuously produced, have high costs, and low first efficiency.

[0011] To solve the above technical problems, the present invention adopts the following technical solutions:

[0012] A system for continuously preparing high-first-efficiency silicon-carbon materials includes 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 that are connected in sequence. A lithium source supply device is connected to the side of the preheating zone B.

[0013] 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 the nitrogen main duct through nitrogen branch ducts; multiple reaction zones divided by staggered baffles A are provided inside the multi-stage silicon precipitation reactor, and each reaction zone is connected to the nitrogen main duct through a purge duct A; multiple reaction zones divided by staggered baffles B are provided inside the multi-stage carbon coating reactor, and each reaction zone is connected to the nitrogen main duct through a purge duct B.

[0014] The multi-stage silicon precipitation reactor is connected to the silane gas main duct through multiple silane gas branch ducts; the multi-stage carbon coating reactor is connected to the acetylene gas main duct through multiple acetylene gas branch ducts.

[0015] Furthermore, the multi-stage silicon precipitation reactor and the multi-stage carbon coating reactor are both arranged horizontally. An air-permeable valve A is installed between the feed port of the multi-stage silicon precipitation reactor and the discharge port of the preheating zone A, an air-permeable valve B is installed between the discharge port of the multi-stage silicon precipitation reactor and the feed port of the preheating zone B, an air-permeable 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 an air-permeable 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.

[0016] Furthermore, the multi-stage silicon precipitation reactor is internally provided with 2 to 8 reaction zones, and staggered baffles A are provided between adjacent reaction zones; the multi-stage carbon coating reactor is internally provided with 2 to 4 reaction zones, and staggered baffles B are provided between adjacent reaction zones.

[0017] Furthermore, 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.

[0018] A process method for continuously preparing high-first-efficiency silicon-carbon materials, applying the above system, includes the following steps:

[0019] Step 1: The porous carbon powder enters the preheating zone A via the raw material bin and then enters the vibrator. After maintaining a certain temperature for a certain period of time, the air-permeable valve A is opened, and the porous carbon powder in the preheating zone A enters the first reaction zone of the multi-stage silicon deposition reactor through nitrogen purging. The multi-stage silicon deposition reactor has been heated to the set temperature, and the porous carbon powder is fluidized by the mixture of nitrogen and silane. After silane cracking for a certain period of time, the silane gas is closed, the gas flow rate of the nitrogen branch air duct is increased, and the corresponding purging air duct A is opened. The powder enters the second reaction zone through the staggered baffle A. The ratio of silane to nitrogen in the mixture is adjusted by the gas flow meter. After silane cracking for a certain period of time, the silane gas is closed, the gas flow rate of the nitrogen branch air duct is increased, and the corresponding purging air duct A is opened. The powder enters the third reaction zone through the staggered baffle A. The ratio of silane to nitrogen in the mixture is adjusted by the gas flow meter. By analogy, the powder enters each reaction zone.

[0020] Step 2: After the reaction in the multi-stage silicon deposition reactor is completed, the air-permeable valve B is opened, and the material enters the preheating zone B. The preheating zone B has been heated to the set temperature, and nitrogen purging is continuously carried out through the nitrogen branch air duct. The lithium source supply device transports the lithium-containing material to the preheating zone B. After maintaining a certain temperature for a certain period of time, the air-permeable valve C is opened, and the material enters the first reaction zone of the multi-stage carbon coating reactor.

[0021] Step 3: The multi-stage carbon coating reactor has been heated to the set temperature, and the material powder is fluidized by the mixture of nitrogen and acetylene. After acetylene cracking for a certain period of time, the acetylene gas is closed, the gas flow rate of the nitrogen branch air duct is increased, and the corresponding purging air duct B is opened. The powder enters the second reaction zone through the staggered baffle B. The ratio of acetylene to nitrogen in the mixture is adjusted by the gas flow meter. After silane cracking for a certain period of time, the acetylene gas is closed, the gas flow rate of the nitrogen branch air duct is increased, and the corresponding purging air duct B is opened. The powder enters the third reaction zone through the staggered baffle B. The ratio of acetylene to nitrogen in the mixture is adjusted by the gas flow meter. By analogy, the powder enters each reaction zone.

[0022] Step 4: After the reaction in the multi-stage carbon coating reactor is completed, the air-permeable valve D is opened, the material is separated by 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.

[0023] Further, the temperature of the preheating zone A is 450 - 500 °C, and the heat preservation time is 10 - 60 min.

[0024] Further, the temperature of the multi-stage silicon deposition reactor is 450 - 500 °C, and 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 ratio of the cavity length L to the inner diameter D of the cavity is 8:1 - 12:1.

[0025] Furthermore, the temperature of the preheating zone B is 550 - 650 °C, and the heat preservation time is 10 - 60 min.

[0026] Furthermore, the temperature of the multi-stage carbon-coated reactor is 550 - 650 °C, and the total carbon coating time is 2 - 8 h.

[0027] Furthermore, the lithium source supply device is one of a thermal evaporation device, a spraying device, and a magnetron sputtering device, and the lithium source raw material of the lithium source supply device is one or more of lithium blocks, lithium foils, lithium powders, lithium hydroxide, lithium carbonate, lithium oxalate, lithium squarate, lithium hydride, butyllithium, naphthyllithium, and biphenylyllithium.

[0028] After the present invention adopts the above technical solutions, compared with the technologies of traditional fixed reactors, rotary kilns, and fluidized beds, it has the following advantages:

[0029] It can realize the large-scale continuous production of silicon-carbon materials, with continuous feeding and discharging, high production efficiency, reduced energy consumption, and lower manufacturing cost of silicon-carbon materials.

[0030] In the whole process, the processes of silicon deposition, lithiation, and carbon coating are all carried out based on the material reaching the fluidized state, with high heat and mass transfer efficiency, better reaction uniformity, high product yield, and the prepared silicon-carbon materials having the characteristic of high initial efficiency.

[0031] Reduce the frequent heating and cooling of the equipment, extend the service life of the equipment, improve the equipment utilization rate, and reduce the comprehensive cost.

[0032] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0033] Figure 1 is a schematic structural diagram of a system for continuously preparing high-initial-efficiency silicon-carbon materials;

[0034] Figure 2 is a summary diagram of the performance and estimated annual production capacity of the silicon-carbon materials prepared in Examples 1 - 4.

[0035] In the figure, 1 - raw material bin, 2 - vibrator, 3 - preheating zone A, 4 - multi - stage silicon precipitation reactor, 5 - fine powder recovery device, 6 - staggered baffle A, 7 - preheating zone B, 8 - multi - stage carbon coating reactor, 9 - staggered baffle B, 10 - silane gas blower, 11 - nitrogen gas blower, 12 - acetylene gas blower, 13 - main silane gas duct, 14 - main nitrogen gas duct, 15 - main acetylene gas duct, 16 - silane gas branch duct, 17 - nitrogen gas 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 - purge duct A, 24 - purge duct B, 25 - breathable valve A, 26 - breathable valve B, 27 - breathable valve C, 28 - breathable valve D, 29 - lithium source supply device. Detailed implementation mode

[0036] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation mode of the present invention will now be described with reference to the accompanying drawings.

[0037] As Figure 1 shown, the present invention provides a system and process method for continuously preparing high - initial - efficiency silicon - carbon materials, including 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 that are connected in sequence. A lithium source supply device 29 is connected to the side of the preheating zone B 7.

[0038] 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 main nitrogen gas duct 14 through nitrogen gas branch ducts 17; multiple reaction zones divided by a staggered baffle A 6 are provided inside the multi - stage silicon precipitation reactor 4, and each reaction zone is connected to the main nitrogen gas duct 14 through a purge duct A 23; multiple reaction zones divided by a staggered baffle B 9 are provided inside the multi - stage carbon coating reactor 8, and each reaction zone is connected to the main nitrogen gas duct 14 through a purge duct B 24. The air inlet of the main nitrogen gas duct 14 is connected to the air outlet of the nitrogen gas blower 11.

[0039] The multi - stage silicon precipitation reactor 4 is connected to the main silane gas duct 13 through multiple silane gas branch ducts 16, and the silane gas branch ducts 16 are arranged in one - to - one correspondence with the reaction zones inside the multi - stage silicon precipitation reactor 4. The air inlet of the main silane gas duct 13 is connected to the air outlet of the silane gas blower 10.

[0040] The multi - stage carbon coating reactor 8 is connected to the main acetylene gas duct 15 through multiple acetylene gas branch ducts 18, and the acetylene gas branch ducts 18 are arranged in one - to - one correspondence with the reaction zones inside the multi - stage carbon coating reactor 8. The air inlet of the main acetylene gas duct 15 is connected to the air outlet of the acetylene gas blower 12.

[0041] Gas flow meters are installed on the air ducts for transporting silane gas, nitrogen gas, and acetylene gas.

[0042] 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.

[0043] The multi-stage silicon deposition reactor 4 and the multi-stage carbon coating reactor 8 are both arranged horizontally. A breathable valve A25 is installed between the feed port of the multi-stage silicon deposition reactor 4 and the discharge port of the preheating zone A3. A breathable valve B26 is installed between the discharge port of the multi-stage silicon deposition reactor 4 and the feed port of the preheating zone B7. A breathable valve C27 is installed between the discharge port of the preheating zone B7 and the feed port of the multi-stage carbon coating reactor 8. A breathable valve D28 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.

[0044] The multi-stage silicon deposition reactor 4 is internally provided with multiple reaction zones, and a staggered baffle A6 is provided between adjacent reaction zones. The staggered baffle A6 divides the reaction zones in the multi-stage silicon deposition reactor 4. In the multi-stage silicon deposition 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.

[0045] The multi-stage carbon coating reactor 8 is internally provided with multiple reaction zones, and a staggered baffle B9 is provided between adjacent reaction zones. The staggered baffle B9 divides the reaction zones in the multi-stage carbon coating reactor 8. In the multi-stage carbon coating reactor 8, its internal area can be divided into two-stage, three-stage, or four-stage reaction zones according to raw material properties, finished product performance requirements, etc.

[0046] Both the staggered baffle A6 and the staggered baffle B9 are composed of two staggered baffles, forming a gap. The width range of the gap is 5 - 15 cm, and gas can pass through normally. The gas flow rate and the gas purge direction determine the passing situation of the powder.

[0047] A fine powder collector 5 is installed above the outlet end of the multi-stage silicon deposition reactor 4. The fine powder collector 5 is connected to the preheating zone A3 through a reflux pipe. The fine powder collector 5 can recover the porous carbon materials with less deposited silicon and less silicon deposition, and transmit them back to the preheating zone A3 through the reflux pipe to improve the powder yield.

[0048] The discharge port of the gas-solid separation device 19 is respectively connected to the tail gas treatment device 20 and the finished product bin 21. A cooling device 22 is arranged outside the finished product bin 21.

[0049] The lithium source supply device 29 is one of a thermal evaporation device, a spraying device, and a magnetron sputtering device.

[0050] A process method for preparing high-performance silicon-carbon materials using the above system, comprising the following steps:

[0051] Step 1: The porous carbon powder enters the vibrator 2 from the raw material bin 1 and then enters the preheating zone A3. After maintaining the temperature for a certain period of time, the air-permeable valve A25 is opened, and the porous carbon powder in the preheating zone A3 enters the first reaction zone of the multi-stage silicon deposition reactor 4 through nitrogen purging. The multi-stage silicon deposition reactor 4 has been heated to the set temperature, and the porous carbon powder is fluidized by the mixture of nitrogen and silane. After silane is cracked for a certain period of time, the silane gas is closed, the gas flow rate of the nitrogen branch air duct 17 is increased, and the corresponding purging air duct A23 is opened. The powder enters the second reaction zone through the staggered baffle A6. The ratio of silane and nitrogen in the mixture is adjusted by the gas flow meter. After silane is cracked for a certain period of time, the silane gas is closed, the gas flow rate of the nitrogen branch air duct 17 is increased, and the corresponding purging air duct A23 is opened. The powder enters the third reaction zone through the staggered baffle A6. The ratio of silane and nitrogen in the mixture is adjusted by the gas flow meter. By analogy, the powder enters each reaction zone;

[0052] Step 2: After the reaction in the multi-stage silicon deposition reactor 4 is completed, the air-permeable valve B26 is opened, and the material enters the preheating zone B7. The preheating zone B7 has been heated to the set temperature, and nitrogen purging is continuously carried out through the nitrogen branch air duct 17. The lithium source supply device 29 transports the lithium-containing material to the preheating zone B7. After maintaining the temperature for a certain period of time, the air-permeable valve C27 is opened, and the material enters the first reaction zone of the multi-stage carbon coating reactor 8;

[0053] Step 3: The multi-stage carbon coating reactor 8 has been heated to the set temperature, and the material powder is fluidized by the mixture of nitrogen and acetylene. After acetylene is cracked for a certain period of time, the acetylene gas is closed, the gas flow rate of the nitrogen branch air duct 17 is increased, and the corresponding purging air duct B24 is opened. The powder enters the second reaction zone through the staggered baffle B9. The ratio of acetylene gas and nitrogen in the mixture is adjusted by the gas flow meter. After silane is cracked for a certain period of time, the acetylene gas is closed, the gas flow rate of the nitrogen branch air duct 17 is increased, and the corresponding purging air duct B24 is opened. The powder enters the third reaction zone through the staggered baffle B9. The ratio of acetylene gas and nitrogen in the mixture is adjusted by the gas flow meter. By analogy, the powder enters each reaction zone;

[0054] Step 4: After the reaction in the multi-stage carbon coating reactor 8 is completed, the air-permeable valve D28 is opened, the material is separated by the gas-solid separation device 19, 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.

[0055] When the continuous production is formed in the present invention, the nitrogen branch air duct 17 and the purge air duct A23 in the multi-stage silicon deposition reactor 4 are in pulsed cooperation, and the nitrogen branch air duct 17 and the purge air duct B24 in the multi-stage carbon coating reactor 8 are in pulsed cooperation, ensuring the smooth flow of materials in each reaction zone of the multi-stage silicon deposition reactor 4 and the multi-stage carbon coating reactor 8.

[0056] In the present invention, the temperature of the preheating zone A3 is 450 - 500 °C, and the heat preservation time is 10 - 60 min.

[0057] 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.

[0058] In the present invention, the shape of the reaction cavity of the multi-stage silicon deposition reactor 4 is circular, and the ratio of the cavity length L to the inner diameter D of the cavity is 8:1 - 12:1.

[0059] In the present invention, the temperature of the preheating zone B7 is 550 - 650 °C, and the heat preservation time is 10 - 60 min.

[0060] In the present invention, the temperature of the multi-stage carbon coating reactor 8 is 550 - 650 °C, and the total carbon coating time is 2 - 8 h.

[0061] In the present invention, the lithium source raw material of the lithium source supply device 29 is one or more of lithium blocks, lithium foils, lithium powders, lithium hydroxide, lithium carbonate, lithium oxalate, lithium squarate, lithium hydride, butyllithium, naphthyllithium, and biphenylyllithium.

[0062] Example 1

[0063] A system for continuously preparing high-first-efficiency silicon-carbon materials, equipment parameters: the inner cavity of the multi-stage silicon deposition reactor is circular, the diameter D is 200 mm, the length L is 2000 mm, and it is divided into four reaction zones; the carbon coating reactor is divided into two reaction zones; the lithium source supply device is a thermal evaporator device.

[0064] This example also provides a process method for preparing high-first-efficiency silicon-carbon materials using the aforementioned system, specifically:

[0065] Step 1: The porous carbon powder enters the preheating zone A via the raw material bin and then enters the vibrator. After being kept at 480°C for 10 minutes, the air-permeable valve A is opened, and after purging with nitrogen, the porous carbon powder in the preheating zone A enters the primary reaction zone of the multi-stage silicon deposition reactor. The multi-stage silicon deposition reactor has been heated to 480°C, and the porous carbon powder is fluidized by the mixed gas of nitrogen and silane. After 30 minutes of silane cracking, the silane gas is closed, the gas flow rate of the nitrogen branch air duct is increased, and the corresponding purging air duct A is opened. The powder enters the secondary reaction zone through the staggered baffle A. The ratio of silane to nitrogen in the mixed gas is adjusted by the gas flowmeter. After 30 minutes of silane cracking, the silane gas is closed, the gas flow rate of the nitrogen branch air duct is increased, and the corresponding purging air duct A is opened. The powder enters the tertiary reaction zone through the staggered baffle A. The ratio of silane to nitrogen in the mixed gas is adjusted by the gas flowmeter. After 30 minutes of silane cracking, the silane gas is closed, the gas flow rate of the nitrogen branch air duct is increased, and the corresponding purging air duct A is opened. The powder enters the quaternary reaction zone through the staggered baffle A. The ratio of silane to nitrogen in the mixed gas is adjusted by the gas flowmeter, and silane is cracked for 30 minutes.

[0066] Step 2: After the reaction in the multi-stage silicon deposition reactor is completed, the air-permeable valve B is opened, and the material enters the preheating zone B. The preheating zone B has been heated to 570°C, and nitrogen purging is continuously carried out through the nitrogen branch air duct. At the same time, the lithium source supply device melts and boils the lithium block at 1400°C to form lithium vapor and transports it to the preheating zone B. After 20 minutes of heat preservation, the air-permeable valve C is opened, and the material enters the primary reaction zone of the multi-stage carbon coating reactor.

[0067] Step 3: The multi-stage carbon coating reactor has been heated to 570°C, and the material powder is fluidized by the mixed gas of nitrogen and acetylene. After 60 minutes of acetylene cracking, the acetylene gas is closed, the gas flow rate of the nitrogen branch air duct is increased, and the corresponding purging air duct B is opened. The powder enters the secondary reaction zone through the staggered baffle B. The ratio of acetylene gas to nitrogen in the mixed gas is adjusted by the gas flowmeter, and silane is cracked for 60 minutes.

[0068] Step 4: After the reaction in the multi-stage carbon coating reactor is completed, the air-permeable valve D is opened, the material is separated by 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.

[0069] The performance and annual production capacity estimation summary of the high-first-efficiency silicon-carbon material prepared by this system are summarized in Figure 2 as shown.

[0070] Example 2

[0071] A system for continuously preparing high-first-efficiency silicon-carbon materials, equipment parameters: The inner cavity of the multi-stage silicon precipitation reactor is circular, with a diameter D of 1000 mm and a length L of 8000 mm, divided into eight reaction zones; the multi-stage carbon coating reactor is divided into four reaction zones; the lithium source supply device is a spraying device.

[0072] This embodiment also provides a process method for preparing high-first-efficiency silicon-carbon materials using the aforementioned system, process parameters: The temperature of preheating zone A is 500 °C, and the heat preservation time is 60 min; the temperature inside the multi-stage silicon precipitation reactor is 500 °C, and the fluidization time for each reaction zone is 70 min; the temperature of preheating zone B is 620 °C, the lithium source supply device melts lithium blocks at 230 °C to form lithium liquid, and the lithium liquid is transported to preheating zone B through a nozzle for heat preservation for 60 min; the temperature inside the multi-stage carbon coating reactor is 620 °C, and the carbon coating time for each reaction zone is 120 min.

[0073] The performance and annual production capacity estimation of the high-first-efficiency silicon-carbon materials prepared by this system are summarized in Figure 2 as shown.

[0074] Example 3

[0075] A system for continuously preparing high-first-efficiency silicon-carbon materials, equipment parameters: The inner cavity of the multi-stage silicon precipitation reactor is circular, with a diameter D of 500 mm and a length L of 6000 mm, divided into six reaction zones; the multi-stage carbon coating reactor is divided into three reaction zones; the lithium source supply device is a magnetron sputtering device.

[0076] This embodiment also provides a process method for preparing high-first-efficiency silicon-carbon materials using the aforementioned system, process parameters: The temperature of preheating zone A is 480 °C, and the heat preservation time is 40 min; the temperature inside the multi-stage silicon precipitation reactor is 480 °C, and the fluidization time for each reaction zone is 75 min; the temperature of preheating zone B is 590 °C, the lithium source supply device uses lithium foil as raw material, and lithium particles are transported to preheating zone B by magnetron sputtering for heat preservation for 40 min; the temperature inside the multi-stage carbon coating reactor is 590 °C, and the carbon coating time for each reaction zone is 75 min.

[0077] The performance and annual production capacity estimation of the high-first-efficiency silicon-carbon materials prepared by this system are summarized in Figure 2 as shown.

[0078] Example 4

[0079] A system for continuously preparing high-first-efficiency silicon-carbon materials, equipment parameters: The inner cavity of the multi-stage silicon precipitation reactor is circular, with a diameter D of 1000 mm and a length L of 8000 mm, divided into eight reaction zones; the multi-stage carbon coating reactor is divided into four reaction zones; the lithium source supply device is a spraying device.

[0080] This embodiment also provides a process method for preparing high-first-efficiency silicon-carbon materials using the aforementioned system, and the process parameters are as follows:

[0081] The temperature of preheating zone A is 490 °C, and the heat preservation time is 60 min; the temperature of the multi-stage silicon precipitation reactor is 490 °C, and the fluidization time for each reaction zone is 70 min; the temperature of preheating zone B is 600 °C. The lithium source supply device dissolves lithium hydroxide in deionized water to form a solution, and the solution is transported to preheating zone B through a nozzle for heat preservation for 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.

[0082] The performance and annual production capacity estimation of the high-first-efficiency silicon-carbon materials prepared by this system are summarized in Figure 2 as shown.

[0083] The above is an example of the best implementation mode of the present invention. The parts not described in detail are all 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-first-efficiency silicon-carbon materials, characterized in that: It includes a raw material bin (1), a preheating zone A (3), a multi-stage silicon deposition reactor (4), a preheating zone B (7), a multi-stage carbon coating reactor (8), and a gas-solid separation device (19) that are connected in sequence. A lithium source supply device (29) is connected to the side of the preheating zone B (7). The preheating zone A (3), the multi-stage silicon deposition reactor (4), the preheating zone B (7), and the multi-stage carbon coating reactor (8) are all connected to a nitrogen main duct (14) through nitrogen branch ducts (17). Inside the multi-stage silicon deposition reactor (4), there are multiple reaction zones divided by staggered baffles A (6), and each reaction zone is connected to the nitrogen main duct (14) through a purge duct A (23). Inside the multi-stage carbon coating reactor (8), there are multiple reaction zones divided by staggered baffles B (9), and each reaction zone is connected to the nitrogen main duct (14) through a purge duct B (24). The multi-stage silicon deposition reactor (4) is connected to a silane gas main duct (13) through multiple silane gas branch ducts (16), and the silane gas branch ducts (16) are arranged in one-to-one correspondence with the reaction zones inside the multi-stage silicon deposition reactor (4). The multi-stage carbon coating reactor (8) is connected to an acetylene gas main duct (15) through multiple acetylene gas branch ducts (18), and the acetylene gas branch ducts (18) are arranged in one-to-one correspondence with the reaction zones inside the multi-stage carbon coating reactor (8).

2. The system for continuously preparing high-first-efficiency silicon-carbon materials according to claim 1, characterized in that: The multi-stage silicon deposition reactor (4) and the multi-stage carbon coating reactor (8) are both arranged horizontally. An air-permeable valve A (25) is installed between the feed port of the multi-stage silicon deposition reactor (4) and the discharge port of the preheating zone A (3). An air-permeable valve B (26) is installed between the discharge port of the multi-stage silicon deposition reactor (4) and the feed port of the preheating zone B (7). An air-permeable valve C (27) is installed between the discharge port of the preheating zone B (7) and the feed port of the multi-stage carbon coating reactor (8). An air-permeable valve D (28) 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-first-efficiency silicon-carbon materials according to claim 1, characterized in that: A fine powder collector (5) is installed above the multi-stage silicon deposition reactor (4) near its outlet end, and the fine powder collector (5) is connected to the preheating zone A (3) through a reflux pipe.

4. A process for continuously preparing a high-first-efficiency silicon-carbon material, applying the system for continuously preparing a high-first-efficiency silicon-carbon material described in any one of claims 1 to 3, characterized in that: It includes the following steps: Step 1: The porous carbon powder enters the vibrator (2) via the raw material bin (1) and then enters the preheating zone A (3). After maintaining the temperature for a certain period of time, the air permeable valve A (25) is opened, and the porous carbon powder in the preheating zone A (3) enters the primary reaction zone of the multi-stage silicon deposition reactor (4) through nitrogen purging. The multi-stage silicon deposition reactor (4) has been heated to the set temperature, and the porous carbon powder is fluidized by the mixture of nitrogen and silane. After silane cracking for a certain period of time, the silane gas is closed, the gas flow rate of the nitrogen branch air duct (17) is increased, and the corresponding purging air duct A (23) is opened. The powder enters the secondary reaction zone through the staggered baffle A (6). The ratio of silane to nitrogen in the mixture is adjusted by the gas flow meter. After silane cracking for a certain period of time, the silane gas is closed, the gas flow rate of the nitrogen branch air duct (17) is increased, and the corresponding purging air duct A (23) is opened. The powder enters the tertiary reaction zone through the staggered baffle A (6). The ratio of silane to nitrogen in the mixture is adjusted by the gas flow meter. By analogy, 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 B (26) is opened, and the material enters the preheating zone B (7). The preheating zone B (7) has been heated to the set temperature, and nitrogen purging is continuously carried out through the nitrogen branch air duct (17). The lithium source supply device (29) transports the lithium-containing material to the preheating zone B (7). After maintaining the temperature for a certain period of time, the air permeable valve C (27) is opened, and the material enters the primary reaction zone of the multi-stage carbon coating reactor (8). Step 3: The multi-stage carbon coating reactor (8) has been heated to the set temperature, and the material powder is fluidized by the mixture of nitrogen and acetylene. After acetylene cracking for a certain period of time, the acetylene gas is closed, the gas flow rate of the nitrogen branch air duct (17) is increased, and the corresponding purging air duct B (24) is opened. The powder enters the secondary reaction zone through the staggered baffle B (9). The ratio of acetylene gas to nitrogen in the mixture is adjusted by the gas flow meter. After silane cracking for a certain period of time, the acetylene gas is closed, the gas flow rate of the nitrogen branch air duct (17) is increased, and the corresponding purging air duct B (24) is opened. The powder enters the tertiary reaction zone through the staggered baffle B (9). The ratio of acetylene gas to nitrogen in the mixture is adjusted by the gas flow meter. By analogy, the powder enters each reaction zone. Step 4: After the reaction in the multi-stage carbon coating reactor (8) is completed, the air permeable valve D (28) is opened, the material is separated by the gas-solid separation device (19), the silicon-carbon material enters the finished product bin (21), and the cooling device (22) is used for cooling. The generated tail gas enters the tail gas treatment device (20).

5. The process method for continuously preparing high-first-efficiency silicon-carbon materials according to claim 4, characterized in that: The temperature of the preheating zone A (3) is 450 - 500 °C, and the heat preservation time is 10 - 60 min.

6. The process method for continuously preparing a high-first-efficiency silicon-carbon material according to claim 4, characterized in that: 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; the shape of the reaction cavity of the multi-stage silicon deposition reactor (4) is circular, and the ratio of the cavity length L to the inner diameter D of the cavity is 8:1 - 12:

1.

7. The process method for continuously preparing high-first-efficiency silicon-carbon materials according to claim 4, characterized in that: The temperature of the preheating zone B (7) is 550 - 650 °C, and the heat preservation time is 10 - 60 min.

8. A process method for continuously preparing a high-first-efficiency silicon-carbon material as described in claim 4, characterized in that: The temperature of the multi-stage carbon coating reactor (8) is 550 to 650 °C, and the total carbon coating time is 2 to 8 h.

9. The process method for continuously preparing high-first-efficiency silicon-carbon materials according to claim 4, characterized in that: The lithium source supply device (29) is one of a thermal evaporation device, a spraying device, and a magnetron sputtering device.

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