A device for producing silicon-carbon material coated by a conical stirring fluidized bed CVD
By designing a conical stirred fluidized bed and controlling the gas precisely, the problems of particle segregation and reaction instability in cylindrical fluidized beds were solved, achieving stable fluidization and efficient production at low gas velocities. This adapts to the silane cracking process and improves the production safety and stability of silicon-carbon materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NOVUSILICON CORP
- Filing Date
- 2025-04-28
- Publication Date
- 2026-06-09
AI Technical Summary
Existing cylindrical fluidized beds suffer from problems such as particle segregation, high dust rate, increased reactor pressure, blockage, and sintering during the production of silicon carbide materials, leading to unstable production and safety hazards. Furthermore, they are difficult to adapt to the instability of volume changes during silane cracking.
The conical stirred fluidized bed design, combined with a stirring paddle and an air hammer, controls the gas flow rate through independent silane, nitrogen and carbon source pipelines. The conical structure suppresses particle separation and enhances the fluidization effect, while the air hammer prevents adhesion to the wall, achieving stable fluidization at low gas velocities.
It achieves full fluidization of particles at low gas velocities, reduces dust rate, improves fluidization quality and heat transfer efficiency, avoids reactor clogging and sintering, adapts to volume changes during silane cracking, and enhances production safety and stability.
Smart Images
Figure CN224332123U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lithium-ion battery technology, specifically to a conical stirred fluidized bed CVD coating silicon-carbon material production device. Background Technology
[0002] With the continuous development of lithium-ion batteries, graphite anode materials on the market have approached their theoretical specific capacity (372 mAh / g). However, the low theoretical specific capacity can no longer meet people's needs, and the higher requirements for battery energy density urgently require a replacement. Among many new anode materials, silicon has attracted widespread attention due to its high specific capacity, low lithium intercalation potential, and excellent fast-charging performance. However, it also has many challenges. The most significant challenge is the volume expansion of silicon anodes during use. The volume change of silicon during charging (lithium intercalation) can reach up to 300% (graphite 12%), which can lead to material breakage and pulverization, severely affecting cycle life. Secondly, the hydrofluoric acid produced by lithium salt decomposition reacts with silicon. Due to the volume changes during charging and discharging, the SEI film is repeatedly damaged, exposing silicon to the electrolyte. This leads to the continuous formation of the SEI film and the continuous consumption of active lithium, resulting in a decrease in capacity. Therefore, composite materials are generally used.
[0003] Chemical vapor deposition (CVD) involves passing silane into sponge-like porous carbon, which then undergoes pyrolysis to generate silicon nanoparticles, which are then deposited on the carbon surface to form a silicon-carbon composite material. The nano-sized silicon and the porosity of the porous carbon significantly reduce the volume expansion caused by lithium intercalation. Due to the small size of the silicon particles, the product has a uniform composition and dense structure, resulting in a low material expansion rate and significantly improved cycle performance, allowing for better utilization of the high capacity advantage of silicon-carbon anodes.
[0004] The core challenges in the industrialization of CVD silicon-carbon anodes lie in the selection of porous carbon, deposition processes, and deposition equipment. Currently, the commonly used deposition equipment is a cylindrical fluidized bed. Due to the small particle size and wide particle size range of porous carbon, cylindrical reactors require high gas velocities to achieve good fluidization quality. However, small-diameter porous carbon particles at high gas velocities can lead to particle separation and high dust rates. When filter rods are used at the top of the reactor, it can cause the reactor pressure to rise, posing a risk of explosion. In the initial stage of the cylindrical reactor reaction, the reaction is violent at the bottom, resulting in a large heat generation per unit volume, which can cause blockage and sintering in the dead zone at the bottom of the reactor. During the siliconization stage, silane decomposition releases gas, and the volume gradually increases as the static pressure decreases, resulting in large fluctuations in the fluidization state and poor stability. Utility Model Content
[0005] The purpose of this invention is to provide a cone-shaped stirred fluidized bed CVD coating silicon carbide material production device.
[0006] To achieve the above objectives, this utility model provides the following technical solution:
[0007] A conical stirred fluidized bed CVD coating silicon-carbon material production apparatus includes a reactor connected to a feed tank via a feed pipe. A stirring paddle is located in the center of the reactor. The bottom of the reactor is connected to a discharge tank via a discharge pipe. A stirring motor for driving the stirring paddle is located below the reactor. A gas input pipe is connected to the bottom of the reactor, and this gas input pipe is connected to a silane pipe, a nitrogen pipe, and a carbon source pipe. The bottom of the reactor is conical.
[0008] The silane pipeline is equipped with a silane flow meter.
[0009] The nitrogen pipeline is equipped with a nitrogen flow meter.
[0010] The carbon source pipeline is equipped with a carbon source flow meter.
[0011] The top outlet of the reactor is connected to the incinerator via an exhaust pipe.
[0012] The agitator is one or a combination of a triangular impeller, a frame impeller, and a ribbon impeller. A frame impeller or a combination of a frame impeller and a ribbon impeller is preferred. The agitation speed can be 20 rpm, 40 rpm, 60 rpm, 80 rpm, or 100 rpm.
[0013] The reactor is equipped with an air hammer, which is used to periodically shake the porous carbon adhering to the reactor wall away from the reactor during the reaction process.
[0014] The reactor has an upper longitudinal section that is an isosceles trapezoid, wider at the top and narrower at the bottom; a middle longitudinal section that is cylindrical; and a lower longitudinal section that is also an isosceles trapezoid, wider at the top and narrower at the bottom. The inclination angles of the upper and lower walls of the reactor are both between 10° and 60°, preferably between 20° and 60°, such as 20°, 40°, or 60°.
[0015] The structural design principle of this conical stirred fluidized bed CVD coating silicon-carbon material production device is as follows:
[0016] 1. Segmented reactor structure:
[0017] The upper part is an inverted isosceles trapezoid with an inclination angle of 10°-60° to suppress particle separation; the middle part is cylindrical to prolong the material residence time; and the lower part is conical with an inclination angle of 20°-60° to enhance the fluidization effect in conjunction with the stirring paddle.
[0018] 2. Synergistic effect of stirring and fluidization:
[0019] Frame-type propellers enhance axial mixing, while ribbon propellers improve radial shearing; their combined use prevents particle agglomeration; multi-speed motors are available for overtime work.
[0020] Speed adjustable (20-100rpm), suitable for different material viscosities.
[0021] 3. Gas input system:
[0022] Independent piping for silane, nitrogen, and silicon source, with precise flow control (flow meter accuracy ±1%); conical bottom gas dispersion.
[0023] The chamber (17) replaces the traditional distribution plate, and the gas flow rate decreases from bottom to top to achieve stable fluidization.
[0024] 4. Anti-sticking design
[0025] A pneumatic hammer is used to periodically vibrate the outer wall of the reactor, which, combined with the action of a stirring paddle, prevents porous carbon from adhering.
[0026] Compared with the prior art, the beneficial effects of this utility model are:
[0027] (1) For particles with a wide particle size distribution, the high linear velocity at the bottom of the cone or cone shape can ensure the fluidization of the particles, while the low linear velocity at the top can suppress particle separation and reduce dust rate. The cone shape achieves full fluidization of particles at low air velocity, with a dust rate ≥30%.
[0028] (2) The conical or cone-shaped bottom of the reactor causes intense turbulence of fluid and solid particles, which can make the fluid evenly distributed in the upper part of the bed. Therefore, the conical inlet can sometimes replace the distribution plate of a general fluidized bed, avoiding the problem of designing the distribution plate or greatly simplifying the design of the distribution plate.
[0029] (3) The device can operate at low gas velocity and obtain better fluidization quality, which cannot be achieved in cylindrical fluidized beds.
[0030] (4) For rapid and high-heat-generating reactions, the turbulent flow at the bottom of the conical bed can help heat be quickly transferred to other low-temperature zones in the bed; the high porosity generated by the high linear velocity at the bottom of the bed also helps to reduce the heat generation per unit volume in the most intense reaction zone, which can effectively prevent dead zones, blockages and sintering phenomena of general fluidized distribution plates; the synergy of stirring and fluidization improves the heat transfer efficiency by 20-40%.
[0031] (5) It can adapt to the reaction process of increasing gas volume. During the reaction, gas or bubbles rise in the bed and the volume will increase accordingly as the static pressure decreases. If gas is released during the reaction, this situation is particularly prominent. Using a conical bed and selecting a certain cone angle can adapt to the requirement of increasing volume, making the fluidization more stable and more adaptable to the volume expansion of silane cracking.
[0032] (6) The production equipment is safe and simple, and can optimize the physical and chemical properties of silicon-carbon materials, greatly improve the overall performance of batteries, and is of great significance for the large-scale production of silicon-carbon coated anode materials. Attached Figure Description
[0033] Figure 1 This is a schematic diagram of a conical stirred fluidized bed CVD coating silicon-carbon material production device. In the diagram, 1-silane flow meter; 2-nitrogen flow meter; 3-carbon source flow meter; 4-feed tank; 5-feed pipeline; 6-reactor; 7-stirring paddle; 8-discharge pipeline; 9-discharge tank; 10-stirring motor.
[0034] Figure 2 The images show the XRD patterns of the silicon-carbon anode material before and after SiC coating in Application Example 1. Detailed Implementation
[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0036] Implementation Cases
[0037] like Figure 1 As shown, a conical stirred fluidized bed CVD coating silicon-carbon material production device includes a reactor 6, which is connected to a feed tank 4 via a feed pipe 5. A stirring paddle 7 is provided in the center of the reactor 6, and the bottom of the reactor 6 is connected to a discharge tank 9 via a discharge pipe 8. A stirring motor 10 for driving the stirring paddle 7 to rotate is provided below the reactor 6. A gas input pipe is connected to the bottom of the reactor 6, and the gas input pipe is connected to a silane pipe, a nitrogen pipe, and a carbon source pipe. The upper longitudinal section of the reactor 6 is an isosceles trapezoid with a wider upper section and a narrower lower section, the middle longitudinal section is a cylinder, and the lower longitudinal section is an isosceles trapezoid with a wider upper section and a narrower lower section.
[0038] A silane flow meter 1 is installed on the silane pipeline. A nitrogen flow meter 2 is installed on the nitrogen pipeline. A carbon source flow meter 3 is installed on the carbon source pipeline. The top outlet of reactor 6 is connected to the incinerator via an exhaust pipeline. The agitator 7 is a frame-type impeller. The stirring speed is 10-120 rpm. The inclination angle of both the upper and lower walls of reactor 6 is 40°.
[0039] The specific steps for using this production device are as follows:
[0040] (1) 50 kg of raw material is pumped from feed tank 4 into reactor 6 using pressure. A frame-type agitator is used, and the agitator is turned on throughout the reaction process.
[0041] (2) Turn on the heating device to heat the reactor 6 and raise the reactor temperature to the predetermined temperature.
[0042] (3) Nitrogen flow meter 2 and silane flow meter 1 are fed into reactor 6 according to the predetermined process, so that silicon source gas and carbon-based material form CVD fluidized deposition in reactor 6 to form silicon-carbon material.
[0043] (4) After the preset time, stop feeding silane gas into reactor 6, introduce nitrogen gas, and continue heating to the carbon coating temperature.
[0044] (5) The carbon source flow meter 3 and the silane flow meter 1 are fed into the reactor 6 in a predetermined ratio.
[0045] (6) After the preset time, stop feeding carbon source gas into reactor 6 and continuously introduce nitrogen gas to reduce the temperature of reactor 6 to room temperature.
[0046] (7) Pressurize and collect the silicon carbide material into the discharge tank 9.
[0047] The siliconization stage mainly involves cracking silanes at high temperatures. The resulting silicon is deposited in porous carbon, and the generated hydrogen gas enters the alkaline spray tank along with nitrogen gas (its main function is to react with undecomposed silanes). The reaction temperature and reaction time are determined based on the BET of the porous carbon raw material.
[0048] Backflushing at the top of the reactor must be carried out continuously to periodically backflush the filter rods and prevent them from becoming clogged or pressurized. At the same time, the reactor is equipped with an air hammer to periodically shake the porous carbon adhering to the reactor wall away from the reactor during the reaction process.
[0049] Application Example 1
[0050] The SiC-coated silicon-carbon anode material was prepared using a conical stirred fluidized bed CVD production apparatus for silicon-carbon coating. The specific steps are as follows:
[0051] (1) Using pressure (40 kPa), 50 kg of raw material is pumped from feed tank 4 into reactor 6. A frame-type impeller is used for stirring, the stirring speed is 60 rpm, and the nitrogen flow rate is 200 L / min.
[0052] (2) Turn on the heating device to heat the reactor 6 and raise the reactor temperature to 500°C.
[0053] (3) Nitrogen gas flow meter 2 and silane gas flow meter 1 are fed into reactor 6 at a volume ratio of 4:1, so that silicon source gas and carbon-based material form CVD fluidized deposition in reactor 6 to form silicon-carbon material.
[0054] (4) After 12 hours, the silicon loading process is completed. After the preset time, stop feeding silane gas into reactor 6, introduce nitrogen gas, and continue to raise the temperature to 650℃.
[0055] (5) The carbon source flow meter 3 and the silane flow meter 1 are fed into the reactor 6 at a volume ratio of 5:1.
[0056] (6) The carbonization process is completed in 2 hours. After the preset time, the carbon source gas is stopped from being fed into reactor 6, and nitrogen is continuously introduced to reduce the temperature of reactor 6 to room temperature.
[0057] (7) Pressurize and collect the silicon carbide material into the discharge tank 9.
[0058] XRD patterns of silicon-carbon anode materials before and after SiC coating are as follows: Figure 2 As shown.
[0059] Application Example 2
[0060] The SiC-coated silicon-carbon anode material was prepared using a conical stirred fluidized bed CVD production apparatus for silicon-carbon coating. The specific steps are as follows:
[0061] (1) Using pressure (40 kPa), 50 kg of raw material is pumped from feed tank 4 into reactor 6. A triangular impeller is used for stirring, the stirring speed is 60 rpm, and the nitrogen flow rate is 200 L / min.
[0062] (2) Turn on the heating device to heat the reactor 6 and raise the reactor temperature to 500°C.
[0063] (3) Nitrogen flow meter 2 and silane flow meter 1 are fed into reactor 6 at a volume ratio of 4:1, so that silicon source gas and carbon-based material form CVD fluidized deposition in reactor 6 to form silicon-carbon material.
[0064] (4) After 12 hours, the silicon loading process is completed. After the preset time, stop feeding silane gas into reactor 6, introduce nitrogen gas, and continue to raise the temperature to 650℃.
[0065] (5) The carbon source flow meter 3 and the silane flow meter 1 are fed into the reactor 6 at a volume ratio of 5:1.
[0066] (6) The carbonization process is completed in 2 hours. After the preset time, the carbon source gas is stopped from being fed into the reactor (6), and nitrogen is continuously introduced to reduce the temperature of the reactor (6) to room temperature.
[0067] (7) Pressurize and collect the silicon carbide material into the discharge tank (9).
[0068] Lithium-ion batteries were fabricated using the SiC-coated silicon-carbon anode material prepared in Application Examples 1-2, and then performance tests were conducted. The results are shown in the table below.
[0069]
[0070] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A conical stirred fluidized bed CVD coating silicon carbide material production apparatus, characterized in that: The reactor (6) is connected to the feed tank (4) via a feed pipe (5). A stirring paddle (7) is provided in the center of the reactor (6). The bottom of the reactor (6) is connected to the discharge tank (9) via a discharge pipe (8). A stirring motor (10) for driving the stirring paddle (7) to rotate is provided below the reactor (6). A gas input pipe is connected to the bottom of the reactor (6). The gas input pipe is connected to a silane pipe, a nitrogen pipe and a carbon source pipe. The upper longitudinal section of the reactor (6) is an isosceles trapezoid with a wider upper section and a narrower lower section. The middle longitudinal section is a cylinder. The lower longitudinal section is an isosceles trapezoid with a wider upper section and a narrower lower section.
2. The cone-shaped stirred fluidized bed CVD coating silicon-carbon material production apparatus according to claim 1, characterized in that: A silane flow meter (1) is installed on the silane pipeline.
3. The cone-shaped stirred fluidized bed CVD coating silicon-carbon material production apparatus according to claim 1, characterized in that: A nitrogen flow meter (2) is installed on the nitrogen pipeline.
4. The cone-shaped stirred fluidized bed CVD coating silicon-carbon material production apparatus according to claim 1, characterized in that: A carbon source flow meter (3) is installed on the carbon source pipeline.
5. The cone-shaped stirred fluidized bed CVD coating silicon-carbon material production apparatus according to claim 1, characterized in that: The top outlet of the reactor (6) is connected to the incinerator via an exhaust pipe.
6. The cone-shaped stirred fluidized bed CVD coating silicon-carbon material production apparatus according to claim 1, characterized in that: The stirring paddle (7) is one or a combination of triangular paddle, frame paddle, and ribbon paddle.
7. The cone-shaped stirred fluidized bed CVD coating silicon-carbon material production apparatus according to claim 1, characterized in that: The reactor (6) is equipped with an air hammer, which is used to periodically shake the porous carbon adhering to the wall away from the reactor (6) during the reaction process.
8. The cone-shaped stirred fluidized bed CVD coating silicon-carbon material production apparatus according to claim 1, characterized in that: The upper and lower walls of the reactor (6) are inclined at angles of 10°-60°.