Silicon nanowire preparation device system and preparation method

Abstract

The invention provides a silicon nanowire preparation device system and a preparation method, the silicon nanowire preparation device system comprises a reaction furnace body and a material supply unit, the material supply unit is used for providing a reducing raw material and a silicon-based raw material into the reaction furnace body; the material supply unit comprises a vaporization module, the vaporization module is located in an inner cavity of the reaction furnace body, and the vaporization module is used for vaporizing a reducing raw material in the reaction furnace body to generate steam, and the steam reacts with a silicon-based raw material to generate the silicon nanowire. The feeding system and the reaction furnace body are integrated, so that the distance of a reaction area is shortened, the stability of raw material supply is effectively ensured, and the stability of a silicon nanowire product is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon nanowire synthesis, and relates to a silicon nanowire preparation device system and a preparation method. Background Art

[0002] With the development of energy technology, people have put forward higher demands on energy storage materials. Silicon materials are regarded as the next generation of negative electrode materials because of their high specific capacity. However, conventional silicon materials will cause material pulverization and slag due to volume expansion during the charging and discharging process, which seriously affects the service life of the battery. Silicon nanowires can maintain good structural stability and cycle performance during the charging and discharging of lithium-ion batteries due to their high surface area and unique quasi-one-dimensional structure. Therefore, the mass production of high-quality silicon nanowires is the key to industrial application.

[0003] At present, in the synthesis process of silicon nanowires, the preparation methods of silicon nanowires can be divided into top-down and bottom-up methods. Among them, the top-down method is to perform directional etching on the silicon substrate through etching technology to obtain a set silicon nanowire array or pattern, but it has high equipment requirements and high costs, and cannot be mass-produced, and is often used in cutting-edge equipment. The mainstream bottom-up process is the VLS (Vapor-Liquid-Soli, gas-liquid-solid) process, which usually uses gas-phase reactants as raw materials, forms a micro-droplet alloy eutectic after reaction, continuously adsorbs the gas-phase Si atoms produced by the reaction, and continuously precipitates and grows into linear nano-silicon under the influence of gravity.

[0004] However, in the VLS process, the generation of vapor has always been a node that is difficult to stably control, especially when it comes to high-temperature metal vapor. Whether it is evaporation, monitoring or transportation, it requires an extremely complex system to control, which seriously restricts the industrialization process. Therefore, the development of a feeding system that can control the vapor feedstock is of great practical significance for the advancement of silicon nanowire synthesis technology.

[0005] In the existing steam transportation method, the crucible is usually placed outside the cavity, and the steam pipe requires high insulation power consumption, especially for high-temperature metal vapor with high melting and boiling points (>800°C), which requires extremely high pipeline insulation power consumption, making overall insulation more difficult. If the insulation effect is not good, the metal vapor condenses in the pipeline, which can easily lead to pipeline blockage and even explosion risk. At the same time, the long pipeline distance leads to a large pressure loss, and a high-pressure system or a vacuum system is required to correct the pressure, which makes it more difficult to detect the concentration of metal vapor. Moreover, in the production process of metal vapor as a reactant, it is easy for the reactant to flow back to the metal evaporator, causing pollution to the raw materials and producing more adverse effects.

[0006] In addition, the engineering difficulty of metal vapor flow control, regulation and feedback is extremely high, and the overall cost of the equipment is high, which is quite difficult in actual engineering application. Therefore, it is necessary to optimize and improve the existing metal vapor generation and transportation, especially the system with metal vapor as the reactant, so as to design, manufacture, maintain and service the evaporator at low cost and high efficiency. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a silicon nanowire preparation device system and preparation method, which integrates the feeding system with the reaction furnace body, shortens the distance between the reaction zones, avoids condensation and deposition of steam before entering the reaction zones, effectively ensures the stability of raw material supply, and improves the stability of silicon nanowire products.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a silicon nanowire preparation device system, the silicon nanowire preparation device system comprising a reaction furnace body and a feeding unit, the feeding unit is used to respectively provide a reducing raw material and a silicon-based raw material into the reaction furnace body;

[0010] The feeding unit comprises a vaporization module, which is located in the inner cavity of the reaction furnace body and is used for vaporizing the reducing raw material in the reaction furnace body to generate steam, and the steam reacts with the silicon-based raw material to generate silicon nanowires.

[0011] In a silicon nanowire preparation device system provided by the present invention, a reaction furnace body has a heating function. The supply and vaporization of heating reducing raw materials are carried out through a vaporization module placed in the inner cavity of the reaction furnace body, thereby realizing the integration of a feeding unit and a reaction furnace, so that the temperature of the reaction furnace body directly heats the feed, thereby reducing the energy consumption of the feed. At the same time, the distance between the feeding unit and the reaction zone of the reaction furnace body is short, thereby avoiding the backflow of silicon-based raw materials, reducing the transportation distance of the reducing raw material vapor, and avoiding condensation or deposition of the steam before entering the reaction zone, thereby effectively ensuring the stability of the raw material supply, growing silicon nanowires through the VLS mechanism, and improving the stability of the silicon nanowire products.

[0012] As a preferred technical solution of the present invention, the feeding unit includes a first material storage module, which is used to accommodate reducing raw materials. The first material storage module is connected to the vaporization module through a feeding pipe. A plurality of discharge holes are distributed on the surface of the feeding pipe located in the reaction furnace body, and the discharge holes connect the feeding pipe and the reaction furnace body.

[0013] It should be noted that in the present invention, the feed pipe extends into the inner cavity of the reactor body and is connected to the vaporization module to directly feed the reducing raw material into the vaporization module for vaporization, and the generated steam enters the reactor body from the discharge hole, effectively shortening the steam transportation distance.

[0014] Preferably, a feeding device is provided at the outlet end of the first material storage module, and the feeding device is connected to the feeding pipeline and is used to feed the reducing raw material into the vaporization module.

[0015] Preferably, the pore size of the discharge hole is 50-100 μm, for example, it can be 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm or 100 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, one end of the feed pipe is connected to the feeding device, and the other end extends from the top of the reaction furnace body into the reaction furnace body and is connected to the vaporization module.

[0017] Preferably, the feeding device comprises a screw feeding device or a vibrating feeding device.

[0018] Preferably, the first storage module comprises a hopper.

[0019] As a preferred technical solution of the present invention, the feeding unit further includes a second material storage module, the second material storage module is used to accommodate silicon-based raw materials, and the second material storage module is connected to the reaction furnace body to provide silicon-based raw materials into the reaction furnace body.

[0020] Preferably, the outlet end of the second material storage module is connected to the top of the reaction furnace body through a feed pump, and the feed pump is used to pump the silicon-based raw material into the reaction furnace body.

[0021] Preferably, a collecting device is further provided at the bottom of the reaction furnace body, and the collecting device is connected to the inlet end of the second material storage module through a condensation reflux device.

[0022] Preferably, the second storage module comprises a storage tank.

[0023] It should be noted that the present invention controls the excess silicon-based raw material fed into the reactor body, and after complete reaction with steam, the excess silicon-based raw material and by-products are recovered by a collecting device, separated by a condensing reflux device, and circulated to the second storage module for reuse.

[0024] As a preferred technical solution of the present invention, the feeding unit also includes a gas supply module, which is connected to the feeding pipeline and is used to introduce a carrier gas into the vaporization module. The carrier gas is used to blow the vaporized reducing raw material into the reactor body.

[0025] Preferably, the gas supply module comprises a heat exchange device, and the heat exchange device is used to heat the carrier gas.

[0026] It should be noted that the carrier gas in the present invention can flow through the discharge hole on the feed pipe. Since the internal pressure of the feed unit is much greater than the pressure in the cavity of the reactor body, the carrier gas is ensured to enter the cavity of the reactor body in the form of high-speed airflow, so that the steam and the silicon-based raw material are evenly mixed in the cavity of the reactor body to react and generate silicon nanowires.

[0027] As a preferred technical solution of the present invention, a support tray is further provided at the bottom of the inner cavity of the reaction furnace body, a catalyst is placed in the support tray, and the support tray is used to grow silicon nanowires.

[0028] Preferably, a tail gas pipeline is also provided at the bottom of the reaction furnace body, and the tail gas pipeline is connected to the outside to discharge the reaction tail gas.

[0029] It should be noted that the tail gas pipeline of the present invention is used to discharge the waste gas after the reaction out of the reaction furnace body, and can be treated with oil seal or water seal.

[0030] In a second aspect, the present invention provides a method for preparing silicon nanowires, wherein the method adopts the silicon nanowire preparation device system according to the first aspect, and the method comprises:

[0031] The reducing raw material is fed into the reaction furnace body and vaporized to form steam, and the steam reacts with the silicon-based raw material in the reaction furnace body to synthesize silicon nanowires.

[0032] The present invention provides a method for preparing silicon nanowires, which utilizes the heating effect of a reaction furnace body to vaporize reducing raw materials in a vaporization module to form steam, so that the steam reacts with the silicon-based raw materials, effectively ensuring the stability of the raw material supply, growing silicon nanowires through the VLS mechanism, and improving the stability of the silicon nanowire products.

[0033] As a preferred technical solution of the present invention, the preparation method specifically comprises the following steps:

[0034] (I) charging the first storage module with a reducing raw material, injecting the silicon-based raw material into the second storage module, and placing the catalyst on a supporting tray;

[0035] (II) introducing a carrier gas into the reaction furnace body by using a gas supply module, and heating the reaction furnace body to a reaction temperature under the protection of the carrier gas;

[0036] (III) driving the first material storage module to deliver the reducing raw material from the feed pipe into the vaporization module to vaporize and form steam, and driving the second material storage module to deliver the silicon-based raw material into the inner cavity of the reaction furnace body, wherein the steam enters the inner cavity of the reaction furnace body from the discharge hole along with the carrier gas and reacts with the silicon-based raw material to grow silicon nanowires on the support tray;

[0037] (IV) After the reaction is completed, the material supply of the first material storage module is stopped, the reaction furnace body is cooled down, and then the material supply of the second material storage module and the gas supply of the gas supply module are stopped.

[0038] As a preferred technical solution of the present invention, in step (I), the reducing raw material includes a reducing metal.

[0039] Preferably, the reducing metal is in the form of particles and / or blocks.

[0040] Preferably, the average particle size D of the reducing metal 50 It is 0.2-1 mm, for example, it can be 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1.0 mm, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the reducing metal includes any one of Fe, Al, Na, K, Zn, Ge or Mg, or a combination of at least two thereof.

[0042] Preferably, the silicon-based raw material comprises an oxygen-free silicon-based compound liquid.

[0043] It should be noted that the present invention utilizes the heating effect of the reaction furnace body to vaporize the reducing raw material in the vaporization module to form steam, and at the same time converts the liquid silicon-based raw material into a gas phase, so that the steam reacts with the gas phase silicon-based raw material, reducing the occurrence of side reactions.

[0044] Preferably, the silicon-based compound liquid includes any one of trichlorosilane, silicon tetrachloride, methyltrichlorosilane or an organic silicon compound, or a combination of at least two thereof.

[0045] Preferably, the catalyst includes any one of Au, Ag, Cu, Sn, Ni or Co, or a combination of at least two thereof.

[0046] Preferably, the catalyst is in the form of nanometer-scale powder and / or micro-nanometer-scale powder.

[0047] As a preferred technical solution of the present invention, in step (II), the carrier gas is heated and then introduced into the vaporization module.

[0048] Preferably, the temperature of the heated carrier gas is 300-800°C, for example, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] Preferably, after the carrier gas is introduced, the pressure in the vaporization module is 1.5 to 3 bar, for example, 1.5 bar, 1.6 bar, 1.8 bar, 2.0 bar, 2.2 bar, 2.5 bar, 2.6 bar, 2.8 bar or 3.0 bar, but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. By maintaining the pressure in the vaporization module, the silicon-based raw material in the inner cavity of the reactor body can be prevented from diffusing into the vaporization module.

[0050] Preferably, the carrier gas comprises Ar and / or N 2 .

[0051] Preferably, the heating rate is 5 to 10°C / min, for example, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] Preferably, the reaction temperature is 50-100°C higher than the boiling point of the reducing raw material, for example, it can be 50°C, 55°C, 60°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] Preferably, the reaction temperature is 800-1200°C, for example, 800°C, 850°C, 900°C, 1000°C, 1100°C or 1200°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] It should be noted that the present invention utilizes the reaction furnace body to directly heat the reducing raw material in the vaporization module, and heats the reaction furnace body until its temperature is higher than the boiling point of the reducing raw material, so that the reducing raw material is vaporized to generate steam.

[0055] Preferably, the reaction time is 30 to 60 min, for example, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 50 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] Preferably, the mass ratio of the reducing raw material to the silicon-based raw material is 1:(1-5), for example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] Preferably, the preparation method further comprises: before the temperature raising treatment, using a carrier gas to displace and purge the inner cavity of the reaction furnace.

[0058] Preferably, after the displacement purge, the pressure in the inner cavity of the reactor body is 1.1-1.2 bar, for example, it can be 1.10 bar, 1.11 bar, 1.12 bar, 1.13 bar, 1.14 bar, 1.15 bar, 1.16 bar, 1.17 bar, 1.18 bar, 1.19 bar or 1.20 bar, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0059] Preferably, the replacement purge time is 60 to 180 min, for example, it can be 60 min, 70 min, 80 min, 90 min, 100 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min or 180 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] It should be noted that the carrier gas in the present invention, on the one hand, plays the role of a protective atmosphere. Before the reaction starts, an unheated carrier gas is used to replace the gas in the reactor body, so that the inner cavity of the reactor body maintains a slightly positive pressure atmosphere protection state, ensuring that the subsequent reaction process is carried out in a protective atmosphere. During the replacement and purging process, the carrier gas enters the feed pipe and flows out from the discharge hole to replace the air in the reactor body, and then is discharged from the tail gas pipe to complete the replacement and purging; on the other hand, the carrier gas plays the role of carrying steam, and the carrier gas is passed into the vaporization unit, so that the pressure in the reactor body is lower than the pressure of the vaporization unit, and the steam generated by vaporization is carried into the reactor body from the discharge hole in a high-speed airflow manner.

[0061] As a preferred technical solution of the present invention, in step (III), the excess silicon-based raw material after the reaction is condensed and refluxed to the second material storage module.

[0062] Preferably, the feeding rate of the first storage module is 1 to 100 g / min, for example, it can be 1 g / min, 2 g / min, 5 g / min, 10 g / min, 20 g / min, 30 g / min, 40 g / min, 45 g / min, 50 g / min, 60 g / min, 70 g / min, 80 g / min, 90 g / min or 100 g / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] Preferably, the feeding rate of the second material storage module (7) is 5 to 300 g / min, for example, it can be 5 g / min, 10 g / min, 20 g / min, 50 g / min, 60 g / min, 80 g / min, 100 g / min, 120 g / min, 150 g / min, 160 g / min, 180 g / min, 200 g / min, 220 g / min, 250 g / min, 280 g / min or 300 g / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0064] It should be noted that the feeding unit in the present invention is relatively stable, and the delivery speed can be adjusted by controlling the feed amount and the internal pressure of the vaporization module, thereby achieving stable delivery of the reducing raw material vapor, and at the same time inhibiting the diffusion of silicon-based raw materials into the vaporization module to produce adverse reactions.

[0065] Preferably, in step (IV), the reaction furnace body is kept warm before the temperature reduction treatment.

[0066] Preferably, the insulation time is 10 to 20 minutes, for example, it can be 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes or 20 minutes, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0067] Preferably, the cooling rate is 3 to 5°C / min, for example, 3.0°C / min, 3.2°C / min, 3.5°C / min, 3.8°C / min, 4.0°C / min, 4.3°C / min, 4.5°C / min, 4.8°C / min or 5.0°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0068] Preferably, after the cooling treatment, the temperature of the reaction furnace body is 500-550°C, for example, it can be 500°C, 505°C, 510°C, 520°C, 525°C, 530°C, 540°C, 545°C or 550°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] Preferably, the preparation method further comprises: in step (IV), after the feeding of the second material storage module (7) is completed, the heating of the carrier gas is first stopped, and under the protection of the carrier gas, the reaction furnace body (6) is naturally cooled to room temperature, and then the gas supply of the gas supply module is stopped.

[0070] It should be noted that the purpose of continuously adding silicon-based raw materials and introducing carrier gas after stopping the feeding of the first material storage module is to consume all the vapor of the evaporated reducing raw materials and prevent the excessive reducing raw materials from generating impurities.

[0071] Preferably, the average wire diameter D of the silicon nanowires is 50 It is 80-140nm, for example, it can be 80nm, 85nm, 90nm, 95nm, 100nm, 110nm, 120nm, 125nm, 130nm, 135nm or 140nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0072] It should be noted that in the present invention, after the temperature of the reaction furnace body is lowered to room temperature, the furnace is opened, the support tray at the bottom is taken out, the grown silicon nanowires are taken out and stored, and the desired product is obtained after washing and purification.

[0073] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0074] The system refers to an equipment system, a device system or a production device.

[0075] Compared with the prior art, the present invention has the following beneficial effects:

[0076] The present invention provides a silicon nanowire preparation device system and a preparation method. The reaction furnace body in the system has a heating function. The reducing raw material is supplied and vaporized by a vaporization module placed in the inner cavity of the reaction furnace body, so that the feeding unit and the reaction furnace are integrated, so that the temperature of the reaction furnace body directly heats the feeding material, thereby reducing the feeding energy consumption. At the same time, the feeding unit is shortly separated from the reaction zone of the reaction furnace body, so that the backflow of silicon-based raw materials is avoided, the transportation distance of the reducing raw material steam is reduced, and condensation or deposition of the steam before entering the reaction zone can be avoided, so that the stability of the raw material supply is effectively guaranteed. In the reaction furnace body, only the reducing raw materials in the gas phase react with the silicon-based raw materials in the gas phase, so that the generation of side reactions is reduced, and the silicon nanowires are grown through the VLS mechanism, so that the yield of the silicon nanowires is improved, so that the product yield reaches more than 85%. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 A schematic diagram of the structure of a silicon nanowire preparation device system provided in Example 1 of the present invention;

[0078] Figure 2 Schematic diagram of silicon nanowires prepared in Application Example 1 of the present invention

[0079] Figure 3 This is a scanning electron microscope image of silicon nanowires prepared in Application Example 1 of the present invention;

[0080] Figure 4 A schematic diagram of silicon nanowires prepared in Application Example 2 of the present invention;

[0081] Figure 5 This is a scanning electron microscope image of silicon nanowires prepared in Application Example 2 of the present invention;

[0082] Figure 6 Schematic diagram of silicon nanowires prepared in Application Example 3 of the present invention;

[0083] Figure 7 This is a scanning electron microscope image of silicon nanowires prepared in Application Example 3 of the present invention;

[0084] Figure 8 A schematic diagram of the structure of a silicon nanowire preparation device system provided in Comparative Example 1 of the present invention;

[0085] Fig. 9 A schematic diagram of silicon nanowires prepared in Comparative Application Example 1 of the present invention;

[0086] Fig.10 This is a scanning electron microscope image of silicon nanowires prepared in comparative application example 1 of the present invention;

[0087] Fig.11 A schematic diagram of silicon nanowires prepared in Comparative Application Example 2 of the present invention;

[0088] Fig.12This is a scanning electron microscope image of silicon nanowires prepared in comparative application example 2 of the present invention;

[0089] Fig.13 A schematic diagram of silicon nanowires prepared in Comparative Application Example 3 of the present invention;

[0090] Fig.14 This is a scanning electron microscope image of silicon nanowires prepared in comparative application example 3 of the present invention.

[0091] Among them, 1-first material storage module; 2-feeding device; 3-feeding pipeline; 4-vaporization module; 5-discharge hole; 6-reaction furnace body; 7-second material storage module; 8-feeding pump; 9-heat exchange device; 10-support tray; 11-condensation reflux device; 12-collecting device; 13-exhaust pipeline; 14-gas supply module; 15-porous quartz material; 16-platform. DETAILED DESCRIPTION

[0092] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0093] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0094] Those skilled in the art should understand that the present invention necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing a complete process, but the above content does not belong to the main inventive point of the present invention. Those skilled in the art can add layouts on their own based on the process flow and equipment structure selection, and the present invention does not make special requirements and specific limitations on this.

[0095] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0096] In a specific embodiment, the present invention provides a silicon nanowire preparation device system, including a reaction furnace body 6 and a feeding unit, wherein the feeding unit is used to provide a reducing raw material and a silicon-based raw material into the reaction furnace body 6 respectively.

[0097] The feeding unit includes a vaporization module 4, which is located in the inner cavity of the reaction furnace body 6. The vaporization module 4 is used to vaporize the reducing raw material in the reaction furnace body 6 to generate steam, and react with the silicon-based raw material to generate silicon nanowires.

[0098] The feeding unit includes a first material storage module 1, which is used to accommodate reducing raw materials and can be a hopper. The first material storage module 1 is connected to the vaporization module 4 through a feeding pipe 3. The surface of the feeding pipe 3 located in the reaction furnace body 6 is distributed with a plurality of discharge holes 5 with an aperture of 50 to 100 μm, and the discharge holes 5 connect the feeding pipe 3 and the reaction furnace body 6. A feeding device 2 is provided at the outlet end of the first material storage module 1. One end of the feeding pipe 3 is connected to the feeding device 2 for providing reducing raw materials, and the other end extends from the top of the reaction furnace body 6 into the reaction furnace body 6 and is connected to the vaporization module 4. The feeding device 2 can be a screw feeding device or a vibrating feeding device with a metering function. The feeding pipe 3 extends into the inner cavity of the reaction furnace body 6 and is connected to the vaporization module 4 to directly feed the reducing raw materials into the vaporization module 4 for vaporization. The generated steam enters the reaction furnace body 6 from the discharge hole 5, which effectively shortens the steam transportation distance. The design and processing structure of the present invention are relatively simple, and the production and maintenance costs are much lower than the existing high-temperature steam transportation process.

[0099] The feeding unit also includes a second storage module 7, which is used to accommodate silicon-based raw materials and can be a storage tank. The outlet end of the second storage module 7 is connected to the top of the reaction furnace body 6 through a feed pump 8, and the feed pump 8 is used to pump the silicon-based raw materials into the reaction furnace body 6. Under the heating action of the reaction furnace body 6, the silicon-based raw materials are converted into gas phase and react with the steam of the reducing raw materials. A collecting device 12 is also provided at the bottom of the reaction furnace body 6, and the collecting device 12 is used to recover excess silicon-based raw materials and by-products, and then connected to the inlet end of the second storage module 7 through a condensation reflux device 11, which is used to condense the gas phase silicon-based raw materials and reflux them to the second storage module 7 for recycling.

[0100] The feeding unit also includes a gas supply module 14, which is connected to the feeding pipeline 3 and is used to pass a carrier gas into the vaporization module 4, and the carrier gas is used to purge the vaporized reducing raw material into the reactor body 6. The gas supply module 14 includes a heat exchange device 9, and the heat exchange device 9 is used to heat the carrier gas. The carrier gas in the present invention flows through the discharge hole 5 on the feeding pipeline 3. Since the internal pressure of the feeding unit is much greater than the pressure in the inner cavity of the reactor body 6, it is ensured that the carrier gas enters the inner cavity of the reactor body 6 in a high-speed airflow mode, so that the steam and the silicon-based raw material are evenly mixed in the inner cavity of the reactor body 6, and react to generate silicon nanowires.

[0101] In some embodiments, a support tray 10 is further disposed at the bottom of the inner cavity of the reaction furnace body 6 , and a catalyst is placed in the support tray 10 . The support tray 10 is used to grow silicon nanowires.

[0102] In some embodiments, a tail gas pipe 13 is further provided at the bottom of the reaction furnace body 6. The tail gas pipe 13 is connected to the outside and is used to discharge the waste gas after the reaction out of the reaction furnace body 6. The tail gas pipe 13 can be treated with an oil seal or a water seal.

[0103] In another specific embodiment, the present invention provides a method for preparing silicon nanowires, wherein the method adopts the silicon nanowire preparation device system described in a specific embodiment, and the method comprises the following steps:

[0104] (1) Fill the first material storage module 1 with reducing raw materials, inject the silicon-based raw materials into the second material storage module 7, and place the catalyst on the surface of the support tray 10. Use the gas supply module 14 to replace and purge the inner cavity of the reaction furnace body 6 for 60 to 180 minutes, so that the pressure in the inner cavity of the reaction furnace body 6 is 1.1 to 1.2 bar;

[0105] (2) The heat exchange device 9 of the gas supply module 14 is turned on to heat the carrier gas to 300-800° C. and pass the carrier gas into the vaporization module 4, so that the pressure in the vaporization module 4 is 1.5-3 bar. Under the protection of the carrier gas, the reaction furnace body 6 is heated at a rate of 5-10° C. / min to 800-1200° C., which is 50-100° C. higher than the boiling point of the reducing raw material. The carrier gas includes Ar and / or N 2 ;

[0106] (3) driving the first material storage module 1 to deliver the reducing raw material from the feed pipe 3 to the vaporization module 4 to vaporize and form steam, and driving the second material storage module 7 to deliver the silicon-based raw material into the inner cavity of the reaction furnace body 6. Under the heating effect of the reaction furnace body 6, the silicon-based raw material is converted into a gas phase, and the steam enters the inner cavity of the reaction furnace body 6 from the discharge hole 5 along with the carrier gas, and reacts with the silicon-based raw material to grow silicon nanowires on the support tray 10;

[0107] (4) After reacting for 30 to 60 minutes, stop feeding the first material storage module 1, keep the temperature for 10 to 20 minutes, then cool the reaction furnace body 6 to 500 to 550° C. at a rate of 3 to 5° C. / min, then stop feeding the second material storage module 7 and heating the carrier gas, and under the protection of the carrier gas, naturally cool the reaction furnace body 6 to room temperature, and then stop supplying gas from the gas supply module 14;

[0108] (5) Open the reaction furnace 6, take out the support tray 10 at the bottom, take out the grown silicon nanowires and store them, and after washing and purification, obtain an average wire diameter D 50 It is a silicon nanowire product with a diameter of 80 to 140 nm.

[0109] Wherein, in step (1), the reducing raw material comprises a granular and / or blocky reducing metal, and the average particle size D of the reducing metal is 50 The diameter of the catalyst is 0.2-1 mm, and the reducing metal includes any one of Fe, Al, Na, K, Zn, Ge or Mg or a combination of at least two thereof. The silicon-based raw material includes an oxygen-free silicon-based compound liquid, including any one of trichlorosilane, silicon tetrachloride, methyltrichlorosilane or an organosilicon compound or a combination of at least two thereof. The catalyst includes any one of Au, Ag, Cu, Sn, Ni or Co or a combination of at least two thereof, and the catalyst is in the form of nano-scale powder and / or micro-nano-scale powder.

[0110] In step (3), the mass ratio of the reducing raw material to the silicon-based raw material is 1:(1.5-4), the feeding rate of the first storage module 1 is 1-100 g / min, the feeding rate of the second storage module 7 is 5-300 g / min, and the mass ratio of the reducing raw material to the silicon-based raw material is ensured to be 1:(1-5).

[0111] In some embodiments, in step (3), the excess silicon-based raw material after the reaction is condensed and then refluxed to the second material storage module 7 for recycling.

[0112] Example 1

[0113] This embodiment provides a silicon nanowire preparation device system, such as Figure 1As shown, it includes a reactor body 6 and a feeding unit. The feeding unit includes a first storage module 1, a second storage module 7 and a gas supply module 14 arranged outside the reactor body 6. The first storage module 1, the second storage module 7 and the gas supply module 14 are used to respectively provide reducing raw materials, silicon-based raw materials and carrier gas into the reactor body 6, and the reactor body 6 is used to react and synthesize silicon nanowires. A support tray 10 is also provided at the bottom of the inner cavity of the reactor body 6, and a catalyst is placed in the support tray 10, and the support tray 10 is used to grow silicon nanowires. An exhaust pipe 13 is also provided at the bottom of the reactor body 6, and the exhaust pipe 13 is connected to the outside to discharge the waste gas after the reaction out of the reactor body 6.

[0114] The feeding unit also includes a vaporization module 4, which is located in the inner cavity of the reactor body 6. The vaporization module 4 is used to vaporize the reducing raw material in the reactor body 6 to generate steam. The first storage module 1 uses a hopper for accommodating the reducing raw material, and is connected to the vaporization module 4 through a feeding pipe 3. The outlet end of the first storage module 1 is provided with a feeding device 2, and the feeding device 2 uses a screw feeding device. One end of the feeding pipe 3 is connected to the feeding device 2, which is used to feed the reducing raw material into the vaporization module 4, and the other end extends from the top of the reactor body 6 into the reactor body 6 and is connected to the vaporization module 4. A plurality of discharge holes 5 with an aperture of 80 μm are distributed on the surface of the feeding pipe 3 located in the reactor body 6. The discharge holes 5 connect the feeding pipe 3 and the reactor body 6, so that the generated steam enters the reactor body 6 from the discharge holes 5, shortening the steam transportation distance.

[0115] The second storage module 7 uses a storage tank for accommodating silicon-based raw materials, and its outlet end is connected to the top of the reaction furnace body 6 through a feed pump 8, which is used to pump the silicon-based raw materials into the reaction furnace body 6. Under the heating action of the reaction furnace body 6, the silicon-based raw materials are converted into a gas phase and react with the steam of the reducing raw materials. A collecting device 12 is also provided at the bottom of the reaction furnace body 6. The collecting device 12 is used to recover excess silicon-based raw materials and by-products, and then connected to the inlet end of the second storage module 7 through a condensation reflux device 11, which is used to condense the gas phase silicon-based raw materials and reflux them to the second storage module 7 to achieve recycling.

[0116] The gas supply module 14 is connected to the feed pipe 3 and is used to supply carrier gas to the vaporization module 4. The carrier gas is used to purge the vaporized reducing raw material into the reaction furnace body 6. The gas supply module 14 includes a heat exchange device 9, which is used to heat the carrier gas.

[0117] Application Example 1

[0118] This application example provides a method for preparing silicon nanowires, which uses the silicon nanowire preparation device system in Example 1 to prepare silicon nanowires, and specifically includes the following steps:

[0119] (1) Fill the first storage module 1 with particles of average particle size D50 The Fe particles are 0.5 mm in diameter, silicon tetrachloride solution is injected into the second material storage module 7, and the catalyst nano-scale Co powder is placed on the surface of the support tray 10, and the inner cavity of the reaction furnace body 6 is replaced and purged for 120 minutes by the gas supply module 14, so that the pressure in the inner cavity of the reaction furnace body 6 is 1.2 bar;

[0120] (2) The heat exchange device 9 of the gas supply module 14 is turned on to heat the carrier gas to 500°C and pass it into the vaporization module 4, so that the pressure in the vaporization module 4 is 2.2 bar. Under the protection of the carrier gas, the reaction furnace body 6 is heated to 1100°C at a rate of 7°C / min. The carrier gas is N 2 ;

[0121] (3) driving the first material storage module 1 to feed Fe particles from the feed pipe 3 into the vaporization module 4 at a feed rate of 50 g / min to vaporize and form steam, and driving the second material storage module 7 to feed the silicon tetrachloride solution into the inner cavity of the reaction furnace body 6 at a feed rate of 200 g / min. Under the heating action of the reaction furnace body 6, the silicon tetrachloride solution is converted into a gas phase, and the steam enters the inner cavity of the reaction furnace body 6 from the discharge hole 5 along with the carrier gas, and reacts with the silicon tetrachloride solution in the gas phase to grow silicon nanowires on the support tray 10. The excess silicon tetrachloride after the reaction is condensed and refluxed to the second material storage module 7 for recycling;

[0122] (4) After the reaction has lasted for 45 minutes, the feeding of the first material storage module 1 is stopped, the temperature is kept at 15 minutes, and then the reaction furnace body 6 is cooled to 550° C. at a rate of 4° C. / min. The feeding of the second material storage module 7 and the heating of the carrier gas are stopped. Under the protection of the carrier gas, the reaction furnace body 6 is naturally cooled to room temperature, and then the gas supply of the gas supply module 14 is stopped;

[0123] (5) Open the reaction furnace body 6, take out the support tray 10 at the bottom, take out the grown silicon nanowires and store them, and obtain the following after washing and purification: Figure 2 and Figure 3 Silicon nanowire product shown.

[0124] Application Example 2

[0125] This application example provides a method for preparing silicon nanowires, which uses the silicon nanowire preparation device system in Example 1 to prepare silicon nanowires, and specifically includes the following steps:

[0126] (1) Fill the first storage module 1 with particles of average particle size D 50The Zn particles are 0.3 mm in diameter, trichlorosilane solution is injected into the second storage module 7, and the catalyst nano-scale Ag powder is placed on the surface of the support tray 10, and the inner cavity of the reaction furnace body 6 is replaced and purged for 60 minutes by the gas supply module 14, so that the pressure in the inner cavity of the reaction furnace body 6 is 1.1 bar;

[0127] (2) The heat exchange device 9 of the gas supply module 14 is turned on to heat the carrier gas to 300° C., and then introduced into the vaporization module 4, so that the pressure in the vaporization module 4 is 1.5 bar. Under the protection of the carrier gas, the reaction furnace body 6 is heated at a rate of 5° C. / min to 800° C., and the carrier gas is Ar;

[0128] (3) driving the first material storage module 1 to feed Zn particles from the feed pipe 3 to the vaporization module 4 at a feed rate of 15 g / min to vaporize and form steam, and driving the second material storage module 7 to feed the trichlorosilane solution into the inner cavity of the reaction furnace body 6 at a feed rate of 60 g / min. Under the heating action of the reaction furnace body 6, the trichlorosilane solution is converted into a gas phase, and the steam enters the inner cavity of the reaction furnace body 6 from the discharge hole 5 along with the carrier gas, and reacts with the gas phase trichlorosilane solution to grow silicon nanowires on the support tray 10. The excess trichlorosilane after the reaction is condensed and refluxed to the second material storage module 7 for recycling;

[0129] (4) After the reaction for 30 minutes, the feeding of the first material storage module 1 was stopped, the temperature was kept at 10 minutes, and then the reaction furnace body 6 was cooled to 520° C. at a rate of 3° C. / min, and then the feeding of the second material storage module 7 and the heating of the carrier gas were stopped. Under the protection of the carrier gas, the reaction furnace body 6 was naturally cooled to room temperature, and then the gas supply of the gas supply module 14 was stopped;

[0130] (5) Open the reaction furnace body 6, take out the support tray 10 at the bottom, take out the grown silicon nanowires and store them, and obtain the following after washing and purification: Figure 4 and Figure 5 Silicon nanowire product shown.

[0131] Application Example 3

[0132] This application example provides a method for preparing silicon nanowires, which uses the silicon nanowire preparation device system in Example 1 to prepare silicon nanowires, and specifically includes the following steps:

[0133] (1) Fill the first storage module 1 with particles of average particle size D 50 A Ge block of 1 mm in diameter is used, a methyltrichlorosilane solution is injected into the second material storage module 7, and a catalyst nano-scale Ni powder is placed on the surface of the support tray 10, and the inner cavity of the reaction furnace body 6 is replaced and purged for 180 minutes using the gas supply module 14, so that the pressure in the inner cavity of the reaction furnace body 6 is 1.2 bar;

[0134] (2) The heat exchange device 9 of the gas supply module 14 is turned on to heat the carrier gas to 800°C, and then introduced into the vaporization module 4, so that the pressure in the vaporization module 4 is 3 bar. Under the protection of the carrier gas, the reaction furnace body 6 is heated to 1200°C at a rate of 10°C / min. The carrier gas is N 2 ;

[0135] (3) driving the first material storage module 1 to feed the Ge block from the feed pipe 3 to the vaporization module 4 at a feed rate of 100 g / min to vaporize and form steam, and driving the second material storage module 7 to feed the methyltrichlorosilane solution into the inner cavity of the reaction furnace body 6 at a feed rate of 300 g / min. Under the heating action of the reaction furnace body 6, the methyltrichlorosilane solution is converted into a gas phase, and the steam enters the inner cavity of the reaction furnace body 6 from the discharge hole 5 along with the carrier gas, and reacts with the gas phase methyltrichlorosilane solution to grow silicon nanowires on the support tray 10. The excess methyltrichlorosilane after the reaction is condensed and refluxed to the second material storage module 7 for recycling;

[0136] (4) After the reaction has lasted for 60 minutes, the feeding of the first material storage module 1 is stopped, the temperature is kept at room temperature for 20 minutes, and the reaction furnace body 6 is cooled to 550° C. at a rate of 5° C. / min. The feeding of the second material storage module 7 and the heating of the carrier gas are stopped. Under the protection of the carrier gas, the reaction furnace body 6 is naturally cooled to room temperature, and then the gas supply of the gas supply module 14 is stopped;

[0137] (5) Open the reaction furnace body 6, take out the support tray 10 at the bottom, take out the grown silicon nanowires and store them, and obtain the following after washing and purification: Figure 6 and Figure 7 Silicon nanowire product shown.

[0138] Comparative Example 1

[0139] This comparative example provides a silicon nanowire preparation device system, such as Figure 8As shown, it includes a reactor body 6 and a feeding unit, and the difference from Example 1 is that: (1) the first storage module 1 is located inside the reactor body 6, and the vaporization module 4 is not provided, wherein the first storage module 1 adopts a quartz boat for accommodating reducing raw materials, and its mouth is covered with a porous quartz material 15 for controlling the escape amount of reducing raw material vapor. The reducing raw material is heated and evaporated into a vapor state in the first storage module 1, and escapes from the pores of the porous quartz material 15 into the reactor body 6; (2) the support tray 10 arranged at the bottom of the inner cavity of the reactor body 6 adopts a quartz boat for accommodating catalysts, and at the same time, the platforms 16 with support frames on both sides are used to limit the raw materials, so that the reaction area of ​​each raw material vapor is concentrated directly above the porous quartz material 15; (3) the gas supply module 14 is connected to the top of the reactor body 6, and the inert gas enters the heat exchange device 9 through the air inlet pipe, which is used to supply inert gas to the entire reaction system, and the heat exchange device 9 is used to heat the inert gas.

[0140] Comparative application example 1

[0141] This application example uses the silicon nanowire preparation device system in Comparative Example 1 to prepare silicon nanowires, and obtains Fig. 9 and Fig.10 The silicon nanowire product shown uses the same preparation materials, operating conditions and process parameters as those in Application Example 1.

[0142] Comparative Application Example 2

[0143] This application example uses the silicon nanowire preparation device system in Comparative Example 1 to prepare silicon nanowires, and obtains Fig.11 and Fig.12 The silicon nanowire product shown uses the same preparation materials, operating conditions and process parameters as those in Application Example 2.

[0144] Comparative Application Example 3

[0145] This application example uses the silicon nanowire preparation device system in Comparative Example 1 to prepare silicon nanowires, and obtains Fig.13 and Fig.14 The silicon nanowire product shown uses the same preparation materials, operating conditions and process parameters as those in Application Example 3.

[0146] The present invention tests the yield, yield rate and average wire diameter of the silicon nanowire products obtained in Applications 1-3 and Comparative Applications 1-3, and the results are shown in Table 1:

[0147] Table 1

[0148] serial number Yield (g) Yield (%) <![CDATA[Average wire diameter (D 50 / nm)]]> Application Example 1 48.74 93.12％ 103.42 Application Example 2 46.88 88.47％ 122.41 Application Example 3 49.12 95.81％ 89.74 Comparative application example 1 35.84 38.48％ 557.21 Comparative Application Example 2 47.83 44.65％ 368.55 Comparative Application Example 3 59.97 67.57％ 487.94

[0149] It can be seen from Table 1 that, compared with the preparation of silicon nanowires in Comparative Example 1, the device system provided in Example 1 in the present invention effectively improves the output and product yield of silicon nanowires. At the same time, the average wire diameter of the silicon nanowires is significantly reduced. This is mainly because a large number of side reactions are generated in the system used in Comparative Example 1, and the molten reducing raw material reacts with the gas phase silicon-based raw material, making the steam transport of the reducing raw material extremely unstable, thereby reducing the product yield.

[0150] The present invention realizes the integration of the feeding unit and the reaction furnace by placing the vaporization module 4 in the reaction furnace body 6 to vaporize the reducing raw material and generate steam, thereby reducing the transportation distance of the reducing raw material steam, stabilizing the steam supply, and only the steam reacts with the gas-phase silicon-based raw material in the reaction furnace body 6, thereby significantly improving the yield and yield of the produced silicon nanowires.

[0151] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A silicon nanowire preparation device system, characterized in that: The silicon nanowire preparation device system comprises a reaction furnace body (6) and a feeding unit, wherein the feeding unit is used to respectively provide a reducing raw material and a silicon-based raw material into the reaction furnace body (6); The feeding unit comprises a vaporization module (4), the vaporization module (4) is located in the inner cavity of the reaction furnace body (6), and the vaporization module (4) is used to vaporize the reducing raw material in the reaction furnace body (6) to generate steam, and the steam reacts with the silicon-based raw material to generate silicon nanowires.

2. The silicon nanowire preparation device system according to claim 1, characterized in that: The feeding unit comprises a first material storage module (1), the first material storage module (1) is used to accommodate reducing raw materials, the first material storage module (1) is connected to the vaporization module (4) via a feeding pipe (3), a surface of the feeding pipe (3) located in the reaction furnace body (6) is provided with a plurality of discharge holes (5), and the discharge holes (5) connect the feeding pipe (3) and the reaction furnace body (6); Preferably, a feeding device (2) is provided at the outlet end of the first material storage module (1), and the feeding device (2) is connected to the feeding pipeline (3) and is used to feed the reducing raw material into the vaporization module (4); Preferably, the aperture of the discharge hole (5) is 50 to 100 μm; Preferably, one end of the feed pipe (3) is connected to the feed device (2), and the other end extends from the top of the reaction furnace body (6) into the reaction furnace body (6) and is connected to the vaporization module (4); Preferably, the feeding device (2) comprises a screw feeding device or a vibrating feeding device; Preferably, the first storage module (1) comprises a hopper.

3. The silicon nanowire preparation device system according to claim 1 or 2, characterized in that: The material supply unit further comprises a second material storage module (7), the second material storage module (7) being used to contain silicon-based raw materials, the second material storage module (7) being connected to the reaction furnace body (6) so as to provide silicon-based raw materials into the reaction furnace body (6); Preferably, the outlet end of the second material storage module (7) is connected to the top of the reaction furnace body (6) via a feed pump (8), and the feed pump (8) is used to pump the silicon-based raw material into the reaction furnace body (6); Preferably, a collecting device (12) is further provided at the bottom of the reaction furnace body (6), and the collecting device (12) is connected to the inlet end of the second material storage module (7) through a condensation reflux device (11); Preferably, the second storage module (7) comprises a storage tank.

4. The silicon nanowire preparation device system according to any one of claims 1 to 3, characterized in that: The feeding unit further comprises a gas supply module, the gas supply module being connected to the feeding pipeline (3) and being used to introduce a carrier gas into the vaporization module (4), the carrier gas being used to purge the vaporized reducing raw material into the reaction furnace body (6); Preferably, the gas supply module comprises a heat exchange device (9), and the heat exchange device (9) is used to heat the carrier gas.

5. The silicon nanowire preparation device system according to any one of claims 1 to 4, characterized in that: A support tray (10) is also provided at the bottom of the inner cavity of the reaction furnace body (6), a catalyst is placed in the support tray (10), and the support tray (10) is used to grow silicon nanowires; Preferably, a tail gas pipeline (13) is further provided at the bottom of the reaction furnace body (6), and the tail gas pipeline (13) is connected to the outside and is used to discharge the reaction tail gas.

6. A method for preparing silicon nanowires, characterized in that: The preparation method adopts the silicon nanowire preparation device system according to any one of claims 1 to 5, and the preparation method comprises: A reducing raw material is fed into a reaction furnace body (10) and vaporized to form steam, and the steam reacts with a silicon-based raw material in the reaction furnace body (10) to synthesize silicon nanowires.

7. The method for preparing silicon nanowires according to claim 6, characterized in that: The preparation method specifically comprises the following steps: (I) charging a reducing raw material into the first material storage module (1), injecting a silicon-based raw material into the second material storage module (7), and placing a catalyst on a supporting tray (10); (II) using a gas supply module to introduce a carrier gas into the reaction furnace body (6), and heating the reaction furnace body (6) to a reaction temperature under the protection of the carrier gas; (III) driving the first material storage module (1) to deliver the reducing raw material from the feed pipe (3) into the vaporization module (4) for vaporization to form steam, and driving the second material storage module (7) to deliver the silicon-based raw material into the inner cavity of the reaction furnace body (6), wherein the steam enters the inner cavity of the reaction furnace body (6) from the discharge hole (5) along with the carrier gas, and reacts with the silicon-based raw material to grow silicon nanowires on the support tray (10); (IV) After the reaction is completed, the material supply of the first material storage module (1) is stopped, the reaction furnace body (6) is cooled down, and then the material supply of the second material storage module (7) and the gas supply of the gas supply module are stopped.

8. The method for preparing silicon nanowires according to claim 7, characterized in that: In step (I), the reducing raw material comprises a reducing metal; Preferably, the reducing metal is in granular and / or massive form; Preferably, the average particle size D of the reducing metal 50 0.2~1mm; Preferably, the reducing metal comprises any one of Fe, Al, Na, K, Zn, Ge or Mg or a combination of at least two thereof; Preferably, the silicon-based raw material comprises a silicon-based compound liquid that does not contain oxygen; Preferably, the silicon-based compound liquid includes any one of trichlorosilane, silicon tetrachloride, methyltrichlorosilane or an organic silicon compound or a combination of at least two thereof; Preferably, the catalyst comprises any one of Au, Ag, Cu, Sn, Ni or Co or a combination of at least two thereof; Preferably, the catalyst is in the form of nanometer-scale powder and / or micro-nanometer-scale powder.

9. The method for preparing silicon nanowires according to claim 7 or 8, characterized in that: In step (II), the carrier gas is heated and then introduced into the vaporization module (4); Preferably, the temperature of the heated carrier gas is 300 to 800°C; Preferably, after the carrier gas is introduced, the pressure in the vaporization module (4) is 1.5 to 3 bar; Preferably, the carrier gas comprises Ar and / or N2; Preferably, the heating rate is 5-10°C / min; Preferably, the reaction temperature is 50 to 100° C. higher than the boiling point of the reducing raw material; Preferably, the reaction temperature is 800-1200°C; Preferably, the reaction time is 30 to 60 minutes; Preferably, the mass ratio of the reducing raw material to the silicon-based raw material is 1:(1-5); Preferably, the preparation method further comprises: before the temperature raising treatment, using a carrier gas to displace and purge the inner cavity of the reaction furnace body (6); Preferably, after the displacement purge, the pressure in the inner cavity of the reaction furnace body (6) is 1.1 to 1.2 bar; Preferably, the displacement purge time is 60 to 180 minutes.

10. The method for preparing silicon nanowires according to any one of claims 7 to 9, characterized in that: In step (III), the excess silicon-based raw material after the reaction is condensed and then refluxed to the second material storage module (7); Preferably, the feeding rate of the first material storage module (1) is 1 to 100 g / min; Preferably, the feeding rate of the second material storage module (7) is 5 to 300 g / min; Preferably, in step (IV), before the temperature reduction treatment, the reaction furnace body (6) is kept warm; Preferably, the insulation time is 10 to 20 minutes; Preferably, the cooling rate is 3-5°C / min; Preferably, after the temperature reduction treatment, the temperature of the reaction furnace body (6) is 500-550°C; Preferably, the preparation method further comprises: in step (IV), after the feeding of the second material storage module (7) is finished, the heating of the carrier gas is first stopped, and under the protection of the carrier gas, the reaction furnace body (6) is naturally cooled to room temperature, and then the gas supply of the gas supply module is stopped; Preferably, the average wire diameter D of the silicon nanowires is 50 It is 80~140nm.

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