Device and preparation method for improving deposition efficiency of silicon-carbon negative electrode prepared by CVD

Abstract

The application relates to the technical field of silicon-carbon negative electrode material preparation devices, in particular to a device for improving the deposition efficiency of CVD-prepared silicon-carbon negative electrodes and a preparation method. The reaction cavity is used for accommodating a base material, and the base material is heated by a heating device to promote the decomposition and deposition reaction of silane gas; an optimized stirring mechanism is designed in the reaction cavity to ensure that the base material can be fully mixed during the reaction; meanwhile, the design of the material lifting plate can ensure that the base material is uniformly lifted during the reaction and fully contacts with the silane gas, so that the mixing uniformity is improved. The gas supply part is responsible for supplying silane gas into the reaction cavity in the stirring process; by accurately controlling the flow and feeding time of the silane gas, the uniform distribution of the silane gas in the reaction cavity can be ensured. The recovery part can also recycle useful components in tail gas, improving the resource utilization rate.

Description

Technical Field

[0001] This invention relates to the field of silicon-carbon anode material preparation equipment, specifically to an equipment and preparation method for improving the deposition efficiency of silicon-carbon anodes prepared by CVD. Background Technology

[0002] Lithium-ion battery anode materials are one of the four main materials for lithium-ion batteries. Currently, graphite anodes are the mainstream, but the specific capacity of commercial graphite anode materials is approaching its theoretical limit, leaving little room for improvement. Silicon-carbon anode materials, with their advantages of high lithium storage capacity and low voltage platform, and the emerging silicon-based materials with extremely high energy density (theoretical specific capacity of 4200 mAh / g, 10 times that of graphite anode materials), are expected to replace graphite anodes as the mainstream direction for the research and development of anode materials for next-generation high-energy-density lithium-ion batteries.

[0003] CVD (Chemical Vapor Deposition) silicon requires a short production process, fewer equipment, and theoretically lower costs, making it the ultimate silicon anode solution for various battery cell manufacturers. Equipment for depositing silicon-carbon materials is currently mainly divided into two categories: rotary kilns and fluidized bed reactors, each with its own advantages and disadvantages. Rotary kiln processes are relatively simple and highly repeatable, hence their widespread adoption by overseas manufacturers. However, this process generally has low deposition efficiency, some silane waste, low batch production volumes, and slightly insufficient particle coverage, thus increasing the cost of mass-produced silicon-carbon products. While fluidized bed reactors do not suffer from uneven deposition or low silane utilization, they require high levels of equipment airtightness and pressure to achieve gaseous coating of small particles, presenting difficulties for large-scale production and thus requiring immediate solutions. Summary of the Invention

[0004] To avoid and overcome the technical problems existing in the prior art, this invention provides an apparatus and a preparation method for improving the deposition efficiency of silicon-carbon anodes prepared by CVD. The apparatus of this invention can effectively improve the mixing uniformity of silane and base material, thereby improving the preparation efficiency of silicon-carbon anode materials.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An apparatus for improving the deposition efficiency of silicon-carbon anodes prepared by CVD includes a reaction chamber for heating and stirring a substrate, a gas supply unit for introducing silane gas into the reaction chamber during the stirring process, and a recovery unit for recovering the tail gas in the reaction chamber. A lifting plate for lifting and stirring the substrate is installed in the reaction chamber.

[0007] As a further embodiment of the present invention: it includes a base and a furnace tube horizontally and rotatably mounted on the base. The furnace tube is cylindrical with a thicker middle and thinner ends, and its transition section is frustum-shaped. The middle section of the furnace tube and its two transition sections constitute the reaction chamber. The lifting plate includes a straight plate installed on the inner wall of the middle section of the furnace tube and a spiral plate installed on the inner wall of the two transition sections. The length direction of each straight plate, which is evenly distributed along the circumference of the furnace tube, is parallel to the axis of the furnace tube, and the height direction of each straight plate extends radially along the furnace tube at its respective position. The spiral plates at the two transition sections are distributed in a spiral shape, and the spiral directions of the spiral plates at the two transition sections are opposite to each other.

[0008] As a further aspect of the present invention: a support frame is also installed on the base, and two sets of rotating components are installed on the support frame, which respectively cooperate with both ends of the furnace tube; each rotating component includes multiple rollers that are uniformly rotated along the circumference of the furnace tube and installed on the support frame, and the rotation axis of each roller is parallel to the axis of the furnace tube; each roller has an annular groove formed by concave in the wheel surface; both ends of the furnace tube are coaxially fixedly installed with rolling rings, which roll and embed into the annular grooves of the rollers they cooperate with; a driven sprocket is coaxially fixedly connected to one end of the furnace tube; a drive motor is fixedly installed on the base; a drive sprocket is coaxially fixedly connected to the motor shaft of the drive motor; and the drive sprocket and the driven sprocket are connected to each other by a transmission chain.

[0009] As a further embodiment of the present invention: a furnace shell is also installed on the base, and a cylindrical furnace chamber is formed inside the furnace shell, which is arranged coaxially with the furnace tube and includes the middle section of the furnace tube and two transition sections. Multiple annular heating plates are uniformly installed coaxially along the furnace chamber axis on the inner wall of the furnace chamber, and the furnace tube is coaxially inserted into the heating cavity formed by the cooperation of multiple annular heating plates.

[0010] As a further embodiment of the present invention: the recovery unit includes an exhaust pipe that is fixedly installed on the base and is coaxially rotated and dynamically sealed with the exhaust end of the furnace tube. The exhaust end of the exhaust pipe extends into the sealed water tank and extends below the water surface of the water tank. The water tank and the clean water circulation system are connected to each other.

[0011] The gas pressure inside the furnace tube is calculated as follows:

[0012] P = (h1 - h2)ρg;

[0013] In the formula, P represents the gas pressure inside the furnace tube; h1 represents the liquid level in the water tank; h2 represents the liquid level difference between the exhaust pipe outlet and the bottom of the water tank; ρ represents the density of water; and g represents the acceleration due to gravity.

[0014] The gas pressure change inside the furnace tube is calculated as follows:

[0015]

[0016] In the formula, ΔP represents the change in gas pressure inside the furnace tube; Qv1 represents the flow rate of the inlet of the clean water circulation system adding clean water to the water tank; Qv2 represents the flow rate of the outlet of the clean water circulation system extracting clean water from the water tank; t represents the working time of the clean water circulation system; and R1 represents the inner radius of the cylindrical water tank.

[0017] As a further embodiment of the present invention: a spiral sleeve is coaxially fixed to the cavity of the gas outlet end of the furnace tube, and an outer spiral plate is fixed to the inner surface of the spiral sleeve; an inner spiral plate is coaxially fixed to the cavity of the spiral sleeve, and the inner spiral plate and the outer spiral plate cooperate with each other to form a spiral channel connecting the reaction chamber and the exhaust pipe.

[0018] As a further embodiment of the present invention: the gas supply unit includes an outer gas guide pipe coaxially rotated and sealed and fitted onto the gas inlet end of the furnace tube. The outer gas guide pipe extends into the reaction chamber and its extension end is a sealed end. Multiple gas guide holes are opened only at the position where the outer gas guide pipe overlaps with the middle section of the furnace tube, and each gas guide hole is arranged evenly along the length direction of the outer gas guide pipe. An inner gas guide pipe is coaxially inserted into the outer gas guide pipe, and the gas outlet end of the inner gas guide pipe extends to the middle position of the furnace tube. The gas inlet end of the inner gas guide pipe is connected to each gas storage tank, and a mass flow meter is installed at the gas outlet end of each gas tank. A static gas mixer is installed at the point where the various gases converge to mix the gases and generate a mixed gas.

[0019] As a further aspect of the present invention: the height of the straight plate is calculated as follows:

[0020] h = 0.3 - 0.4R;

[0021] In the formula, h represents the width of the straight plate; and represents the inner radius of the middle section of the furnace tube.

[0022] As a further aspect of the present invention: the minimum inner radius of the furnace tube transition section is r, calculated as follows:

[0023] r = 1.2 - 1.5(Q / πVa) 0.5 ;

[0024]

[0025] In the formula, Q represents the flow rate of the mixed gas entering the reaction chamber; Va represents the flow velocity of the mixed gas entering the reaction chamber; K represents the correction parameter; L represents the length of the middle section of the furnace tube; n represents the rotational speed of the furnace tube; δ represents the deposition efficiency of silane in the mixed gas; and α represents the maximum angle at which silane in the mixed gas can maintain a natural and stable state when deposited on the substrate, i.e., the angle of repose.

[0026] The preparation method, which utilizes the aforementioned apparatus for improving the deposition efficiency of silicon-carbon anodes prepared by CVD, is characterized by comprising the following preparation steps:

[0027] S1. Assemble the device and simultaneously place porous carbon, which serves as the base material, into the furnace tube;

[0028] S2. Mix silane, acetylene and nitrogen according to the set ratio, and introduce the mixed gas into the reaction chamber. At the same time, the furnace tube rotates in the opposite direction of the spiral plate, the annular heating plate heats the furnace tube, and the clean water circulation system operates according to the set flow rate.

[0029] S3. The mixed gas reacts with the porous carbon, and the remaining gas enters the water tank and is extracted by the centrifugal fan according to the set power.

[0030] S4. After the reaction time is set, stop the device. At this point, the preparation of silicon-carbon anode material is complete.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1. The reaction chamber of this invention is used to contain the base material, and a heating device heats the base material to promote the decomposition and deposition reaction of silane gas. The reaction chamber is designed with an optimized stirring mechanism to ensure that the base material is fully mixed during the reaction. Simultaneously, the design of the lifting plate ensures that the base material is evenly lifted during the reaction and fully contacts the silane gas, thereby improving mixing uniformity. The gas supply unit is responsible for introducing silane gas into the reaction chamber during the stirring process; by precisely controlling the flow rate and introduction time of the silane gas, uniform distribution of the silane gas within the reaction chamber can be ensured. The recovery unit can also recover and reuse useful components in the exhaust gas, improving resource utilization.

[0033] 2. When the exhaust gas of this invention passes through the spiral sleeve, the airflow rotates with the spiral channel, generating a certain centrifugal force. The powder carried in the exhaust gas is affected by the centrifugal force and is deposited. The deposited material gradually falls back into the spiral plate near it under the action of the spiral channel. Then, under the reverse pushing action of the spiral plate, it re-enters the middle section of the furnace tube to continue to react with the base material, reducing material loss.

[0034] 3. Based on the gas pressure calculation formula in the furnace tube, this invention shows that by controlling the flow rate of the inlet and outlet of the clear water circulation system, the gas pressure in the furnace tube can be changed according to actual needs, thereby stably controlling the gas pressure in the furnace tube and providing a stable atmosphere environment for the high-temperature deposition of gas in the furnace tube.

[0035] 4. The arrangement of the external and internal gas guide pipes and the location of the gas guide holes in this invention enable the mixed gas to form a gas curtain that blows towards the furnace tube wall during the discharge process, thereby improving the uniformity of contact between the mixed gas and the base material, and thus improving the reaction efficiency of silane and porous carbon. Attached Figure Description

[0036] Figure 1This is a schematic diagram of the overall structure of the device of the present invention.

[0037] Figure 2 This is a schematic diagram of the furnace tube structure in this invention.

[0038] Figure 3 This is a schematic diagram of the gas supply unit in this invention.

[0039] Figure 4 This is a schematic diagram of the spiral sleeve in this invention.

[0040] Figure 5 This is a schematic diagram of the recovery section in this invention.

[0041] Figure 6 This is a schematic diagram of the dimensions and structure of the straight plate in this invention.

[0042] In the diagram: 1. Base; 11. Telescopic rod; 2. Base; 21. Support frame; 211. Support roller; 3. Furnace tube; 3a. Middle section; 3b. Transition section; 31. Lifting plate; 311. Straight plate; 312. Spiral plate; 32. Rolling ring; 33. Driven sprocket; 34. Reaction chamber; 4. Spiral sleeve; 41. Outer spiral plate; 42. Inner spiral plate; 43. Spiral channel; 5. Recovery section; 51. Exhaust pipe; 52. Clean water circulation system; 53. Centrifugal fan; 54. Water tank; 541. Level gauge; 6. Gas supply section; 61. Gas tank; 62. Mass flow meter; 63. Static gas mixer; 64. Outer gas guide pipe; 641. Gas guide hole; 65. Inner gas guide pipe. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Please see Figures 1-6 In use, the device of the present invention first fixes the base 1 in the corresponding position, and then uses a hydraulic cylinder, which serves as a telescopic rod 11, to drive the base 2, which is hinged to the base 1, to be leveled. Next, porous carbon, which serves as the base material, is added into the reaction chamber 34 from the feed inlet on the right side of the furnace tube 3 in a set amount. Then, the rotating sleeve and the inner spiral plate 42 are fixedly installed in the cavity at the feed inlet on the right side of the furnace tube 3. Finally, the gas supply unit 6 and the recovery unit 5 are connected sequentially to both ends of the furnace tube 3.

[0045] In this embodiment, four gas cylinders 61 are used, two of which are filled with nitrogen, with one nitrogen cylinder 61 serving as a spare. The other two gas cylinders 61 are filled with silane and acetylene, respectively. After the acetylene, silane, and nitrogen pass through their respective mass flow meters 62, the nitrogen and acetylene are uniformly mixed in a static gas mixer 63, while the nitrogen and silane are uniformly mixed in another static gas mixer 63. The two mixed gases are then mixed again in the inner gas guide pipe 65 to form the final mixed gas, which is then sent into the reaction chamber 34 through the gas guide hole 641 in the outer gas guide pipe 64. The flow rate Q of the mixed gas entering the reaction chamber 34 is calculated by formula (1):

[0046]

[0047] During the monitoring of the initial gas flow using mass flow meter 62, the ratio of silane to nitrogen is controlled at 1:3, and the ratio of acetylene to nitrogen is also 1:3. Simultaneously, nitrogen is continuously introduced into the interlayer between the inner gas guide pipe 65 and the outer gas guide pipe 64 using a spare nitrogen tank 61. This lowers the temperature inside the composite pipe formed by the combination of the outer and inner gas guide pipes 64 and 65, thus reducing the process gas temperature and preventing decomposition of the mixed gas before it contacts the porous carbon after entering the furnace tube 3 due to excessively high temperature, which would affect the coating quality. Furthermore, the composite pipe is inserted into the inlet end of the furnace tube 3 using a common coaxial rotary seal and fixed to the base 2. This ensures that the composite pipe remains stationary during the rotation of the furnace tube 3, improving the stability of the gas flow.

[0048] The mixed gas continuously enters the furnace tube 3. Simultaneously, driven by the drive motor and the transmission chain, the driven sprocket 33 rotates the furnace tube 3. The rollers 211 mounted on the support frame 21 engage with the rolling ring 32, providing a rotational basis for the furnace tube 3 and improving rotational stability. The horizontally arranged furnace tube 3 rotates continuously, and its direction of rotation is opposite to the vortex direction of the spiral plate 312 in the transition section 3b. This causes the spiral plate 312 to push the porous carbon diffused into the transition section 3b back into the middle section 3a of the furnace tube 3. Under the lifting action of the straight plate 311 in the lifting plate 31, the carbon is continuously tumbled and stirred, thus achieving full contact and reaction with the mixed gas. The spiral plates 312 at both ends of the furnace tube 3 rotate in opposite directions: the right-hand spiral plate 312 rotates clockwise, and the left-hand spiral plate 312 rotates counterclockwise. During sintering, furnace tube 3 rotates counterclockwise. The straight plate 311 ensures uniform material feeding in the middle, increasing the uniformity of particle coating. The spiral plates 312 at both ends prevent the raised powder from spreading to both ends and push the powder accumulated in the transition section 3b of furnace tube 3 to the middle of furnace tube 3. The temperature difference between the transition section 3b and the middle section 3a of furnace tube 3 is relatively large, preventing uneven powder coating at both ends. During discharge, furnace tube 3 rotates in the opposite direction to push the material out of furnace tube 3.

[0049] In this embodiment, the height of the straight plate 311 is also required. It is calculated by formula (2). When the number of lifting plates 31 and the number of straight plates 311 are 6, R < 600mm; when the number of straight plates 311 is 8, 600mm ≤ R < 1000mm.

[0050] h = 0.3 - 0.4R (2)

[0051] Meanwhile, the minimum inner radius of the transition section 3b of furnace tube 3 is r, calculated as shown in formula (3):

[0052] r = 1.2 - 1.5(Q / πVa) 0.5 (3)

[0053] During the sintering process, the furnace chamber is encased in insulation material made of high-quality ceramic fiber. A ring-shaped heating plate is embedded within the insulation material, enclosing the furnace tube 3. This ensures uniform heating of the furnace tube 3, minimizes the temperature difference within its cross-section, and maintains consistent silane decomposition and deposition efficiency. The heat collector plate can be a conventional plate made of resistance wire; however, other materials or structures capable of time-based heating are also feasible.

[0054] The exhaust gas produced after the mixed gas reacts in the porous carbon reactor passes through the spiral channel 43 formed by the outer spiral plate 41 and the inner spiral plate 42 in the filter sleeve, and then enters the exhaust pipe 51. At the same time, the exhaust pipe 51 is inserted into the gas outlet end of the furnace tube 3 using a common coaxial rotary seal and is fixed on the base 2 so that the exhaust pipe 51 remains fixed during the rotation of the furnace tube 3, thereby improving the stability of the exhaust.

[0055] The high-temperature resistant packing sealing material on the outside of the spiral sleeve 4 ensures a seal between the rotating sleeve and the pipe wall, preventing material leakage from this part. The exhaust pipe 51 sends the exhaust gas into the water tank 54 below the water surface, causing some substances in the exhaust gas to dissolve in the water and be carried away by the clean water circulation system 52. The remaining gas floats in the upper space of the water tank 54 and is drawn away by the centrifugal fan 53 for centralized treatment.

[0056] Numerical flow meters are installed at both the inlet and outlet of the water circulation system 52, which connects to the water tank 54. The flow rate can be measured in real time using these numerical flow meters. A level gauge 541 is installed at the bottom of the water tank 54 to collect the water level height data h1 in real time and transmit it to the control system. At the same time, the distance between the exhaust pipe 51 and the bottom of the water tank 54 is h2. The gas pressure in the reaction chamber 34 can be calculated using formula (4).

[0057] P=(h1-h2)ρg (4)

[0058] Since the water in tank 54 is constantly circulating, the value of ρ remains basically unchanged. The gas pressure in furnace tube 3 is directly proportional to the vertical distance h1-h2 between the water pipe and the water surface. The volumetric flow rates Qv1 and Qv2 of the inlet and outlet water are controlled by numerical liquid flow meters, and the pressure P of furnace tube 3 is adjusted. The pressure change of furnace tube 3 is shown in formula (5).

[0059]

[0060] The gas pressure control method described above for furnace tube 3 stably controls the gas pressure in furnace tube 3, providing a stable atmospheric environment for the high-temperature deposition of gas inside furnace tube 3.

[0061] After the set reaction time is reached, sintering is stopped, and the connection between the exhaust pipe 51 and the furnace tube 3 is disconnected. At the same time, the spiral sleeve 4 is removed. At this time, under the action of the hydraulic cylinder, one end of the base 2 is lifted, and under the action of the drive motor, the furnace tube 3 reverses, thereby pouring all the material in the furnace tube 3 into the collection box. This completes the preparation of silicon-carbon anode material for this round.

[0062] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An apparatus for improving the deposition efficiency of silicon-carbon anodes prepared by CVD, characterized in that, It includes a reaction chamber (34) for heating and stirring the base material, a gas supply unit (6) for introducing silane gas into the reaction chamber (34) during the stirring process, and a recovery unit (5) for recovering the tail gas in the reaction chamber (34). A lifting plate (31) for lifting and stirring the base material is installed in the reaction chamber (34). The furnace tube (3) is a cylindrical shape that is thicker in the middle and thinner at both ends, and its transition section (3b) is a frustum shape. The middle section (3a) and the two transition sections (3b) of the furnace tube (3) constitute the reaction chamber (34). The lifting plate (31) includes a straight plate (311) installed on the inner wall of the middle section (3a) of the furnace tube (3) and a spiral plate (312) installed on the inner wall of the two transition sections (3b). The length direction of each straight plate (311) evenly distributed around the furnace tube (3) is parallel to the axis of the furnace tube (3), and the height direction of each straight plate (311) extends radially along the furnace tube (3) at its respective position. The spiral plates (312) at the two transition sections (3b) are distributed in a spiral shape, and the spiral plate (312) at the two transition sections (3b) have opposite spiral directions. The gas supply unit (6) includes an external gas guide pipe (64) that is coaxially rotated and sealed and fitted to the gas inlet end of the furnace tube (3). The external gas guide pipe (64) extends into the reaction chamber (34) and its extension end is a sealed end. The external gas guide pipe (64) has multiple gas guide holes (641) only at the position where it overlaps with the middle section (3a) of the furnace tube (3). Each gas guide hole (641) is arranged evenly along the length of the external gas guide pipe (64). An internal gas guide pipe (65) is coaxially inserted inside the external gas guide pipe (64). The gas outlet end of the internal gas guide pipe (65) extends to the middle position of the furnace tube (3). The gas inlet end of the internal gas guide pipe (65) is connected to each gas tank (61) that stores gas. Each gas tank (61) is equipped with a mass flow meter (62) at its gas outlet end. A static gas mixer (63) is installed at the point where various gases converge to mix the gases and generate a mixed gas.

2. The apparatus for improving the deposition efficiency of silicon-carbon anodes prepared by CVD according to claim 1, characterized in that, A support frame (21) is also installed on the base (2). Two sets of rotating components are installed on the support frame (21) respectively, which are matched with the two ends of the furnace tube (3). Each rotating component includes multiple rollers (211) that are installed on the support frame (21) in a uniform manner along the circumference of the furnace tube (3). The rotation axis of each roller (211) is parallel to the axis of the furnace tube (3). The wheel surface of each roller (211) is concave to form an annular groove. Both ends of the furnace tube (3) are coaxially fixedly installed with rolling rings (32). The rolling rings (32) are rolled and embedded in the annular grooves of each roller (211) that they match. One end of the furnace tube (3) is coaxially fixedly connected with a driven sprocket (33). A drive motor is fixedly installed on the base (2). A drive sprocket is coaxially fixedly connected to the motor shaft of the drive motor. The drive sprocket and the driven sprocket (33) are connected to each other through a transmission chain.

3. The apparatus for improving the deposition efficiency of silicon-carbon anodes prepared by CVD according to claim 2, characterized in that, A furnace shell is also installed on the base (2). Inside the furnace shell, a cylindrical furnace chamber is formed, which is arranged coaxially with the furnace tube (3) and includes the middle section (3a) and two transition sections (3b) of the furnace tube (3). Multiple annular heating plates are evenly installed coaxially along the furnace chamber axis on the inner wall of the furnace chamber. The furnace tube (3) is coaxially inserted into the heating cavity formed by the cooperation of multiple annular heating plates.

4. An apparatus for improving the deposition efficiency of silicon-carbon anodes prepared by CVD according to any one of claims 1-3, characterized in that, The recycling unit (5) includes an exhaust pipe (51) that is fixedly installed on the base (2) and rotates and seals with the exhaust end of the furnace tube (3) on the same axis. The exhaust end of the exhaust pipe (51) extends into the sealed water tank (54) and extends below the water surface of the water tank (54). The water tank (54) is connected to the clean water circulation system (52). The gas pressure inside the furnace tube (3) is calculated as follows: ； In the formula, P represents the gas pressure inside the furnace tube (3); h1 represents the liquid level in the water tank (54); h2 represents the liquid level difference between the exhaust pipe (51) outlet and the bottom of the water tank (54); ρ represents the density of water; and g represents the acceleration due to gravity.

5. The apparatus for improving the deposition efficiency of silicon-carbon anodes prepared by CVD according to claim 4, characterized in that, A spiral sleeve (4) is coaxially fixed inside the cavity of the gas outlet end of the furnace tube (3), and an outer spiral plate (41) is fixed on the inner surface of the spiral sleeve (4); an inner spiral plate (42) is coaxially fixed in the cavity of the spiral sleeve (4), and the inner spiral plate (42) and the outer spiral plate (41) cooperate with each other to form a spiral channel (43) connecting the reaction chamber (34) and the exhaust pipe (51).

6. A preparation method, wherein the preparation method utilizes the apparatus described in claim 5 for improving the deposition efficiency of silicon-carbon anodes prepared by CVD, characterized in that, The preparation steps include the following: S1, assemble the device and simultaneously place porous carbon as the base material in the furnace tube (3); S2. Mix silane, acetylene and nitrogen according to the set ratio and introduce the mixed gas into the reaction chamber (34). At the same time, the furnace tube (3) rotates in the opposite direction of the spiral plate (312), the annular heating plate heats the furnace tube (3), and the water circulation system (52) operates according to the set flow rate. S3. The mixed gas reacts with the porous carbon, and the remaining gas enters the water tank (54) and is extracted by the centrifugal fan (53) according to the set power. S4. After the reaction time is set, stop the device. At this point, the preparation of silicon-carbon anode material is complete.

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