A system and process for scalable preparation of high-initial-efficiency silicon-carbon materials

Abstract

The present invention discloses a system and process method for scalably preparing high-initial-efficiency silicon-carbon materials, which belongs to the technical field of preparing negative electrode materials for lithium-ion batteries. The system for preparing high-initial-efficiency silicon-carbon materials includes a raw material warehouse, wherein the discharge port of the raw material warehouse is respectively connected to the feed ports of several silicon precipitation reactors through a material conveying pipeline, the discharge ports of several silicon precipitation reactors are connected to the feed port of a mixing warehouse, the discharge port of the mixing warehouse is connected to the feed port of a carbon coating reactor, the side of the carbon coating reactor is connected to a lithium source supply device, and the carbon coating reactor is provided with two discharge ports, which discharge materials to a finished product warehouse and a spare warehouse respectively; it also includes a silane gas blower, a nitrogen gas blower, an acetylene gas blower and a PLC control system. The present invention provides a system and process method for scalably preparing high-initial-efficiency silicon-carbon materials to solve the current technical problems of low production efficiency, high cost and low initial efficiency of silicon-carbon materials.

Description

Technical Field

[0001] The present invention relates to a system and a process method for scalably preparing high-initial-efficiency silicon-carbon materials, belonging to the technical field of preparing negative electrode materials for lithium-ion batteries. Background Art

[0002] With the accelerated development of cutting-edge fields such as new energy vehicles, humanoid robots, and low-altitude aircraft, lithium-ion batteries are facing higher performance thresholds, requiring increased energy density, enhanced safety and reliability, and guaranteed long cycle life. Currently commercialized graphite anodes are limited by a theoretical capacity ceiling of 372mAh / g, making it difficult to meet this demand. Silicon-based anode materials, with a theoretical capacity of up to 4200mAh / g, experience significant volume deformation of 300% during the lithiation / delithiation process, leading to pulverization and failure of the electrode structure, making it difficult to overcome the bottleneck of industrial application.

[0003] The industry has recently achieved key progress through process innovation: using chemical vapor deposition (CVD) technology to achieve controlled deposition of nano-silicon particles within a porous carbon network, while simultaneously constructing a dense carbon coating on the outside. This "three-dimensional carbon skeleton + gradient buffer protective layer" composite system design has increased the measured gram capacity of the silicon-carbon composite anode to 1800mAh / g, and the cycling stability has exceeded 1500 cycles, significantly narrowing the gap between laboratory performance and engineering application.

[0004] However, the current silicon-carbon production capacity is mainly achieved by using decentralized silicon-settling fluidized bed equipment with a single batch production capacity of 20kg or 50kg combined with carbon-coated rotary kiln equipment. The initial equipment investment and fixed plant investment costs are high, the degree of intelligence is low, the production efficiency is low, and the batch stability is poor, which is not conducive to the application and promotion of silicon-carbon materials. In addition, the first efficiency of most silicon-carbon materials is relatively low, only 80-85%, while the first efficiency of lithium iron phosphate materials can reach more than 95%, and the first efficiency 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.

[0005] Therefore, there is an urgent need to provide a system and process method for scalably preparing high-initial-efficiency silicon-carbon materials to solve the above problems. Summary of the Invention

[0006] In response to the deficiencies in the background technology, the present invention provides a system and process method for scalably preparing high-initial-efficiency silicon-carbon materials, so as to solve the current technical problems of low production efficiency, high cost and low initial efficiency of silicon-carbon materials.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A system for scalable preparation of high-initial-effect silicon-carbon materials includes a raw material bin, wherein the discharge port of the raw material bin is connected to the feed ports of several silicon precipitation reactors through material conveying pipelines, the discharge ports of the several silicon precipitation reactors are connected to the feed port of a mixing bin, the discharge port of the mixing bin is connected to the feed port of a carbon coating reactor, a lithium source supply device is connected to the side of the carbon coating reactor, and the carbon coating reactor is provided with two discharge ports, which discharge materials to a finished product bin and a spare bin respectively; it also includes a silane gas blower, a nitrogen gas blower, an acetylene gas blower and a PLC control system.

[0009] Furthermore, the silane gas blower is connected to the bottom of several silicon precipitation reactors through pipelines, the nitrogen gas blower is connected to the bottom of several silicon precipitation reactors, the mixing bin, and the carbon coating reactor through pipelines, and the acetylene gas blower is connected to the bottom of the carbon coating reactor through pipelines.

[0010] Furthermore, the tail gas from several silicon precipitation reactors and carbon coating reactors is connected to the tail gas treatment system through the tail gas delivery pipeline.

[0011] Furthermore, the number of the silicon precipitation reactors is two to twelve; the number of the mixing bins is one or two; and the number of the carbon coating reactors is one to three.

[0012] Furthermore, the lithium source supply device is one of a thermal evaporation device, a spray device or a magnetron sputtering device.

[0013] A process for scalably preparing high-initial-efficiency silicon-carbon materials, using the above-mentioned system for scalably preparing high-initial-efficiency silicon-carbon materials, comprises the following steps:

[0014] S1, the porous carbon powder in the raw material bin enters several silicon precipitation reactors through the material conveying pipeline. It is first heated and fluidized by nitrogen purge. After keeping warm for a certain period of time, a mixture of nitrogen and silane is introduced. After the silane is cracked for a certain period of time, the intermediate material is conveyed to the mixing bin.

[0015] S2. The mixing bin is preheated to a certain temperature in advance, and the materials delivered from several silicon precipitation reactors are batch mixed by physical methods. After being kept warm for a certain period of time, the materials are transported to the carbon coating reactor;

[0016] S3. The carbon coating reactor has been heated to the set temperature. The powder is fluidized by nitrogen purge. The lithium source supply device delivers lithium-containing material to the carbon coating reactor. After a certain period of insulation, a mixture of nitrogen and acetylene is introduced. After a certain period of acetylene cracking, the qualified products are sent to the finished product silo, and the unqualified products are sent to the spare silo.

[0017] Furthermore, the reaction chamber of the silicon deposition reactor is cylindrical in shape, wherein the ratio of the chamber height H to the chamber inner diameter D is in the range of 8:1 to 12:1.

[0018] Furthermore, the inner diameter D of the reaction chamber of the silicon deposition reactor is 300-800 mm; the temperature in the silicon deposition reactor is 450-500° C., and the total silicon deposition reaction time is 2-10 hours.

[0019] Furthermore, the temperature in the carbon coating reactor is 550-650° C., and the total carbon coating time is 2-8 hours.

[0020] Furthermore, the lithium source raw material of the lithium source supply device is one or more of lithium block, lithium foil, lithium powder, lithium hydroxide, lithium carbonate, lithium oxalate, lithium squarate, lithium hydride, butyl lithium, naphthalene lithium, and biphenyl lithium.

[0021] After adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0022] 1. It can realize the large-scale production of silicon-carbon materials, with high production efficiency, reduced energy consumption, and lower manufacturing costs of silicon-carbon materials;

[0023] 2. Throughout the entire process, silicon deposition, pre-lithiation, and carbon coating are all carried out under a fluidized state, resulting in high heat and mass transfer efficiency, good reaction uniformity, and no need for frequent cooling.

[0024] 3. The entire production process is controlled by the PLC system, which makes the control more precise; the shared feeding system, mixing system, gas system, and exhaust gas treatment system greatly reduce the equipment investment cost;

[0025] 4. The prepared silicon-carbon material has the characteristics of high capacity, long cycle and high initial efficiency.

[0026] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of a system that can be used to prepare high-initial-efficiency silicon-carbon materials on a large scale;

[0028] Figure 2 This is a summary diagram of the performance and annual production capacity estimates of the silicon-carbon materials prepared in specific Examples 1-4.

[0029] In the figure, 1-raw material warehouse, 2-material conveying pipeline, 3-silicon precipitation reactor, 4-mixing warehouse, 5-carbon coating reactor, 6-lithium source supply device, 7-finished product warehouse, 8-spare warehouse, 9-exhaust gas conveying pipeline, 10-exhaust gas treatment system, 11-silane gas blower, 12-nitrogen blower, 13-acetylene gas blower, 14-PLC control system. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0031] like Figure 1 As shown, the present invention provides a system for scalable preparation of high-first-effect silicon-carbon materials, including a raw material bin 1, the discharge port of the raw material bin 1 is connected to the feed ports of several silicon precipitation reactors 3 through a material conveying pipe 2, the discharge ports of several silicon precipitation reactors 3 are connected to the feed port of a mixing bin 4, the discharge port of the mixing bin 4 is connected to the feed port of a carbon coating reactor 5, the side of the carbon coating reactor 5 is connected to a lithium source supply device 6, and the carbon coating reactor 5 is provided with two discharge ports, which discharge materials to a finished product bin 7 and a spare bin 8 respectively; it also includes a silane gas blower 11, a nitrogen blower 12, an acetylene gas blower 13 and a PLC control system 14.

[0032] The silane gas blower 11 is connected to the bottom of several silicon precipitation reactors 3 through pipelines, the nitrogen blower 12 is connected to the bottom of several silicon precipitation reactors 3, the mixing bin 4, and the carbon coating reactor 5 through pipelines, and the acetylene gas blower 13 is connected to the bottom of the carbon coating reactor 5 through pipelines.

[0033] The tail gas from the several silicon precipitation reactors 3 and the carbon coating reactor 5 is connected to the tail gas treatment system 10 through the tail gas delivery pipeline 9 .

[0034] The PLC control system 14 controls the feeding, reaction and discharging processes with PLC and human-machine interface as the core.

[0035] In the present invention, the number of silicon deposition reactors 3 is two to twelve.

[0036] In the present invention, the number of the mixing bins 4 is one or two.

[0037] In the present invention, the number of the carbon-coated reactors 5 is one to three.

[0038] In the present invention, the lithium source supply device 6 is a thermal evaporation device, a spray device or a magnetron sputtering device.

[0039] A process for preparing a high-initial-efficiency silicon-carbon material using the above system comprises the following steps:

[0040] Step 1: The porous carbon powder in the raw material bin 1 is fed into several silicon precipitation reactors 3 through the material conveying pipe 2. It is first heated and fluidized by nitrogen purge. After being kept warm for a certain period of time, a mixture of nitrogen and silane is introduced. After the silane is cracked for a certain period of time, the intermediate material is conveyed to the mixing bin 4.

[0041] Step 2: The mixing bin 4 is preheated to a certain temperature in advance, and the materials delivered from the several silicon precipitation reactors 3 are batch mixed by physical methods (vibration, stirring, air flow dispersion, etc.). After being kept warm for a certain period of time, the materials are transported to the carbon coating reactor 5;

[0042] Step 3: The carbon-coated reactor 5 is heated to the set temperature, and the powder is fluidized by nitrogen purge. The lithium source supply device 6 delivers lithium-containing material to the carbon-coated reactor 5. After keeping warm for a certain period of time, a mixture of nitrogen and acetylene is introduced. After acetylene cracking for a certain period of time, the qualified products are sent to the finished product silo 7, and the unqualified products are sent to the spare silo 8.

[0043] During the reaction process, the tail gas generated by the several silicon precipitation reactors 3 and the carbon coating reactor 5 enters the tail gas treatment system 10 (alkali solution washing tank, spray combustion, etc.) through the tail gas delivery pipeline 9 for treatment.

[0044] In the present invention, the reaction chamber of the silicon deposition reactor 3 is cylindrical in shape, wherein the ratio of the chamber height H to the chamber inner diameter D is in the range of 8:1 to 12:1.

[0045] In the present invention, the inner diameter D of the reaction chamber of the silicon precipitation reactor 3 is 300-800 mm.

[0046] In the present invention, the temperature in the silicon precipitation reactor 3 is 450-500° C., and the total silicon precipitation reaction time is 2-10 hours.

[0047] In the present invention, the temperature in the carbon coating reactor 5 is 550-650° C., and the total carbon coating time is 2-8 hours.

[0048] In the present invention, the lithium source raw material of the lithium source supply device 6 is one or more of lithium block, lithium foil, lithium powder, lithium hydroxide, lithium carbonate, lithium oxalate, lithium squarate, lithium hydride, butyl lithium, naphthalene lithium, and biphenyl lithium. Example 1

[0049] A system for scalable preparation of high-first-effect silicon-carbon materials. Equipment parameters: the inner cavity of the silicon precipitation reactor is cylindrical, with a diameter D of 300mm and a height H of 3000mm, and there are twelve of them; there are two mixing silos; there are three carbon-coated reactors; and the lithium source supply device is a thermal evaporator device.

[0050] This embodiment also provides a process for preparing a high-initial-efficiency silicon-carbon material using the aforementioned system, specifically:

[0051] Step 1: The porous carbon powder in the raw material bin is fed into twelve silicon precipitation reactors through the material delivery pipeline. It is first heated, purged with nitrogen and fluidized, and kept at 490°C for 60 minutes. Then, a mixture of nitrogen and silane is introduced. After silane is cracked for 8 hours, the intermediate material is transported to the mixing bin.

[0052] Step 2: Preheat the two mixing bins to 590°C in advance, and batch mix the materials delivered from six silicon precipitation reactors using physical methods (vibration, stirring, airflow dispersion, etc.). After keeping the temperature for 60 minutes, the materials are transported to the carbon coating reactor.

[0053] Step 3: The carbon-coated reactor is heated to 590°C, and the powder is fluidized by nitrogen purge. The lithium source supply device melts and boils the lithium block at 1400°C to form lithium vapor which is transported to the carbon-coated reactor. After keeping warm for 20 minutes, a mixture of nitrogen and acetylene is introduced. After acetylene cracking for 8 hours, qualified products are sent to the finished product silo, and unqualified products are sent to the spare silo.

[0054] The performance and annual production capacity of silicon-carbon materials prepared by this system are summarized in Figure 2 Shown in. Example 2

[0055] A system for scalable preparation of high-initial-efficiency silicon-carbon materials. Equipment parameters: the inner cavity of the silicon precipitation reactor is cylindrical, with a diameter D of 800mm and a height H of 7000mm, and there are two of them; there is one mixing bin; there is one carbon coating reactor; and the lithium source supply device is a spray device.

[0056] This embodiment also provides a process method for preparing high-first-effect silicon-carbon materials using the aforementioned system, with specific process parameters: the temperature of the silicon precipitation reactor is 460°C, and the reaction time is 10 hours; the temperature of the mixing bin is 620°C, and it is kept warm for 1 hour; the lithium source supply device melts the lithium block at 230°C to form lithium liquid, and the lithium liquid is transported to the carbon coating reactor through the nozzle and kept warm for 60 minutes; the temperature of the carbon coating reactor is 620°C, and the reaction time is 6 hours.

[0057] The performance and annual production capacity of silicon-carbon materials prepared by this system are summarized in Figure 2 Shown in. Example 3

[0058] A system for scalable preparation of high-initial-efficiency silicon-carbon materials. Equipment parameters: the inner cavity of the silicon precipitation reactor is cylindrical, with a diameter D of 450mm and a height H of 5000mm, and there are ten of them; there are two mixing silos; there are three carbon-coated reactors; and the lithium source supply device is a spray device.

[0059] This embodiment also provides a process method for preparing high-first-effect silicon-carbon materials using the aforementioned system, with specific process parameters: the temperature of the silicon precipitation reactor is 490°C, and the reaction time is 4 hours; the temperature of the mixing bin is 600°C, and it is kept warm for 1 hour; the lithium source supply device melts the lithium block at 230°C to form lithium liquid, and the lithium liquid is transported to the carbon coating reactor through the nozzle and kept warm for 60 minutes; the temperature of the carbon coating reactor is 600°C, and the reaction time is 4 hours.

[0060] The performance and annual production capacity of silicon-carbon materials prepared by this system are summarized in Figure 2 Shown in. Example 4

[0061] A system for scalable preparation of high-initial-efficiency silicon-carbon materials. Equipment parameters: the inner cavity of the silicon precipitation reactor is cylindrical, with a diameter D of 450mm and a height H of 5000mm, and there are ten of them; there are two mixing bins; there are three carbon-coated reactors; and the lithium source supply device is a magnetron sputtering device.

[0062] This embodiment also provides a process method for preparing high-first-effect silicon-carbon materials using the aforementioned system. The specific process parameters are: the temperature of the silicon precipitation reactor is 490°C, and the reaction time is 4 hours; the temperature of the mixing bin is 600°C, and it is kept warm for 1 hour; the lithium source supply device uses lithium foil as raw material, and transports lithium particles to the carbon coating reactor by magnetron sputtering and keeps them warm for 40 minutes; the temperature of the carbon coating reactor is 600°C, and the reaction time is 4 hours.

[0063] The performance and annual production capacity of silicon-carbon materials prepared by this system are summarized in Figure 2 Shown in.

[0064] The foregoing is an example of the best mode of carrying out the present invention. Any portion not described in detail herein is common knowledge within the skill of one of ordinary skill in the art. The scope of protection of the present invention is determined by the claims. Any equivalent transformation based on the technical teachings of the present invention is also within the scope of protection of the present invention.

Claims

1. A system for scalable preparation of high-initial-efficiency silicon-carbon materials, characterized in that: The invention comprises a raw material bin (1), wherein the discharge port of the raw material bin (1) is connected to the feed ports of several silicon precipitation reactors (3) through a material conveying pipe (2), the discharge ports of the several silicon precipitation reactors (3) are connected to the feed port of a mixing bin (4), the discharge port of the mixing bin (4) is connected to the feed port of a carbon coating reactor (5), the side of the carbon coating reactor (5) is connected to a lithium source supply device (6), and the carbon coating reactor (5) is provided with two discharge ports, which respectively discharge materials to a finished product bin (7) and a spare bin (8); It also includes a silane gas blower (11), a nitrogen gas blower (12), an acetylene gas blower (13) and a PLC control system (14). The silane gas blower (11) is connected to the bottom of the plurality of silicon precipitation reactors (3) through pipelines, the nitrogen gas blower (12) is connected to the bottom of the plurality of silicon precipitation reactors (3), the mixing bin (4) and the carbon coating reactor (5) through pipelines, and the acetylene gas blower (13) is connected to the bottom of the carbon coating reactor (5) through pipelines; the tail gas of the plurality of silicon precipitation reactors (3) and the carbon coating reactor (5) is connected to the tail gas treatment system (10) through the tail gas delivery pipeline (9); The lithium source supply device (6) is a thermal evaporation device, a spray device or a magnetron sputtering device.

2. A process for scalably preparing high-initial-efficiency silicon-carbon materials, using the system for scalably preparing high-initial-efficiency silicon-carbon materials according to claim 1, characterized in that: The following steps are involved: The porous carbon powder in the raw material bin (1) is fed into several silicon precipitation reactors (3) through the material conveying pipe (2). It is first heated and fluidized by nitrogen purge. After being kept warm for a certain period of time, a mixture of nitrogen and silane is introduced. After the silane is cracked for a certain period of time, the intermediate material is conveyed to the mixing bin (4). S2, the mixing bin (4) is preheated to a certain temperature in advance, and the materials delivered from the several silicon precipitation reactors (3) are batch mixed by physical methods. After being kept warm for a certain period of time, the materials are transported to the carbon coating reactor (5); S3, the carbon coating reactor (5) has been heated to the set temperature, and the powder is fluidized by nitrogen purge, and the lithium source supply device (6) delivers the lithium-containing material to the carbon coating reactor (5). After the temperature is kept for a certain period of time, a nitrogen and acetylene mixture is introduced. After the acetylene is cracked for a certain period of time, the qualified products are sent to the finished product bin (7), and the unqualified products are sent to the spare bin (8); The reaction chamber of the silicon deposition reactor (3) is cylindrical in shape, wherein the ratio of the chamber height H to the chamber inner diameter D is 8:1 to 12:1; the reaction chamber inner diameter D of the silicon deposition reactor (3) is 300 to 800 mm; the temperature in the silicon deposition reactor (3) is 450 to 500° C., and the total silicon deposition reaction time is 2 to 10 hours; The temperature in the carbon coating reactor (5) is 550-650°C, and the total carbon coating time is 2-8 hours; The lithium source raw material of the lithium source supply device is lithium oxalate / lithium squarate.

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