Method and apparatus for manufacturing silicon microparticles and silicon microparticles manufactured thereby

Abstract

The present invention relates to a method and an apparatus for manufacturing silicon microparticles and silicon microparticles manufactured thereby. More specifically, the present invention relates to a method and an apparatus capable of manufacturing silicon particles having a controlled grain size, a spherical shape, and a size of several micrometers (㎛), and to silicon microparticles manufactured thereby.

Description

Method for manufacturing silicon microparticles, manufacturing apparatus, and silicon microparticles manufactured thereby

[0001] The present invention relates to a method for manufacturing silicon microparticles, a manufacturing apparatus, and silicon microparticles manufactured thereby. More specifically, the present invention relates to a method and apparatus for manufacturing silicon particles having a controlled crystal grain size, a spherical shape, and a size of several micrometers (㎛), and to silicon microparticles manufactured thereby.

[0002] The performance improvement of secondary batteries is based on the components of positive electrode materials, negative electrode materials, and electrolyte.

[0003] Among the above components, graphite-based materials, which are mainly used as cathode materials, are commercially available due to their excellent electrochemical performance and low cost, but their theoretical capacity is limited to 370 mAh / g, which limits their application to high-capacity secondary batteries.

[0004] To overcome the above limitations, non-graphite anode materials such as silicon, tin, and germanium are emerging as alternatives. Among them, silicon has a theoretical capacity of 4,000–4,200 mAh / g, demonstrating nearly 10 times the capacity of graphite, and is thus attracting attention as a material to replace graphite. However, compared to its high theoretical capacity, it experiences significant volume expansion of approximately 400% during the charge and discharge process, resulting in structural destruction of the material and a short lifespan.

[0005] To address these limitations, methods have been developed to control silicon particle sizes down to the micrometer or nanometer range. Typically, these methods involve manufacturing polysilicon particles or crushing silicon materials, such as silicon chunks obtained from other industrial fields or processing processes.

[0006] Specifically, methods for manufacturing polysilicon particles include the Siemens method using a bell-shaped reactor and the FBR method using a fluidized bed reactor.

[0007] Among these, the Siemens method is a method of reacting a silicon source gas on a silicon rod provided in a reactor to deposit silicon on the surface of the rod. However, the surface area required for silicon deposition is limited, and there is a limit to the diameter of the silicon rod that increases due to the deposition reaction, so a continuous process is impossible, and since the power consumption per unit weight of silicon is high, there is a limit to low productivity.

[0008] The FBR method involves placing a silicon seed in a crucible through which hydrogen gas flows, injecting silicon source gas, causing the silicon seed to fall and precipitate silicon particles of about 1 cm in diameter around it. This method produces silicon faster than the Siemens method, but has the problem of lower quality of the silicon produced.

[0009] Conventionally, to obtain micro-sized silicon from polysilicon particles manufactured in this manner, a separate grinding process is required, and an additional sorting process is also required after the grinding, resulting in a complex process and low efficiency. Furthermore, the grinding process generates unintended impurities and fine particles, making it nearly impossible to control the sphericity of micrometer-sized particles.

[0010] In addition, as described above, the FBR method also has the problem that an additional purification process is required because the impurity content is high even during the process in which the silicon seed comes into contact with the inner wall of the reactor in the fluidized bed reactor.

[0011] Methods for directly manufacturing silicon nanoparticles are being developed, including a method for manufacturing by irradiating a target silicon metal with a laser beam, a method for manufacturing by thermally decomposing a precursor including silicon using ultraviolet rays in a solvent, and a plasma method for manufacturing silicon nanoparticles by generating plasma to decompose a silicon precursor.

[0012] Meanwhile, when using silicon nanoparticles as active materials for secondary batteries, the silicon particles are too small, resulting in poor dispersibility when applied as a cathode slurry, and this can reduce the lifespan and capacity retention of the secondary battery. Conversely, if the silicon particles become too large, mechanical stress during the charging and discharging process can cause deterioration.

[0013] Therefore, there is a demand for manufacturing silicon particles having a micro size. However, it is difficult to manufacture silicon particles having a micro size using conventional methods for manufacturing silicon nanoparticles, and there are limitations in controlling sphericity and crystal grains.

[0014] In addition, conventional methods for manufacturing silicon nanoparticles, such as lasers and plasma, have limitations in achieving mass production due to their high cost. Therefore, it is expected that it will be difficult to achieve mass production using technologies for manufacturing silicon microparticles using lasers and plasma.

[0015] In this way, considering the dispersibility of silicon particles and the activity due to the specific surface area of ​​silicon particles, the demand for silicon microparticles is increasing in many fields. Therefore, it is necessary to develop a technology that can directly and efficiently manufacture silicon microparticles. Furthermore, it is still necessary to develop a manufacturing method that can secure the crystal grain size and sphericity of silicon microparticles and a manufacturing device to implement the same.

[0016] The purpose of the present invention is to provide silicon microparticles having a crystal grain size of 40 nm or less, high sphericity, and a particle diameter of several hundred nm to several ㎛.

[0017] In addition, the present invention aims to provide a method for manufacturing silicon microparticles suitable for mass production and a manufacturing device for implementing the same, by economically and efficiently manufacturing silicon microparticles having a crystal grain size of 40 nm or less, a high sphericity, and a particle diameter of several hundred nm to several ㎛ without additional processes such as a grinding process or a sorting process.

[0018] The purpose of the present invention is not limited to the aforementioned purposes, and other unmentioned purposes and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0019] In order to achieve the above purpose, according to the first aspect of the present invention,

[0020] (S1) A step of introducing a silicon source gas mixture containing two or more silicon source gases having different decomposition temperatures and hydrogen gas into a reactor;

[0021] (S2) a step of decomposing a silicon source gas mixture in the reactor to produce silicon microparticles;

[0022] The above-mentioned generated silicon microparticles have an average crystal grain size of 40 nm or less and an average particle diameter (D 50 ) is 100 nm to 10 ㎛ and has a sphericity of 80% or more.

[0023] A method for manufacturing silicon microparticles can be provided.

[0024] The above silicon source gas mixture may be a mixture of two or more silicon source gases selected from the silicon source gases represented by the following chemical formula 1 or chemical formula 2.

[0025] [Chemical Formula 1] SiH x Cl 4-x (x is an integer from 0 to 4)

[0026] [Chemical Formula 2] Si2H y Cl 6-y (y is an integer from 0 to 6)

[0027] The silicon source gas represented by the above chemical formula 1 or 2 may be selected from monosilane (SiH4) gas, dichlorosilane (SiH2Cl2) gas, trichlorosilane (SiHCl3) gas, tetrachlorosilane (SiCl4) gas, dichlorosilane hexachlorosilane (Si2Cl6) gas, and disilane (Si2H6) gas.

[0028] The above silicon source gas mixture includes a first silicon source gas and a second silicon source gas, and the decomposition temperature of the first silicon source gas is lower than the decomposition temperature of the second silicon source gas.

[0029] The decomposition temperature of the first silicon source gas may be 350°C to 600°C, and the decomposition temperature of the second silicon source gas may be 600°C to 1000°C.

[0030] The first silicon source gas and the second silicon source gas can be introduced in a molar ratio of 1:0.2 to 1:6.

[0031] The above silicon source gas mixture and hydrogen gas can be introduced at a molar ratio of 1:0.5 to 1:10.

[0032] The temperature of the reactor is 700°C to 1,000°C, and the temperature at the top of the reactor can be gradiently increased to be higher than the temperature at the bottom of the reactor.

[0033] In the above reactor, the generation of silicon seeds and the growth of silicon particles from the continuously generated silicon seeds can proceed simultaneously.

[0034] In the above step (S2), the reaction time of the silicon source gas mixture in the reactor for producing silicon microparticles may be from 5 minutes to 3 hours.

[0035] In the above method for manufacturing silicon microparticles, a carrier gas may be further introduced into the reactor.

[0036] According to the second aspect of the present invention,

[0037] Raw gas injection section;

[0038] Raw gas mixing device;

[0039] pyrolysis reactor;

[0040] a heating element surrounding the reactor; and

[0041] Including a gas discharge part,

[0042] The above pyrolysis reactor can provide a device for manufacturing silicon microparticles, in which a turbulent flow region formed at the upper portion of the pyrolysis reactor and a laminar flow region formed at the lower portion of the pyrolysis reactor coexist.

[0043] The internal structure forming a turbulent flow region and a laminar flow region is included inside the pyrolysis reactor, and the material of the internal structure has heat resistance of 700°C to 1000°C and may include at least one selected from graphite, quartz, and ceramic.

[0044] The above silicon microparticle manufacturing device may be a device for implementing the silicon microparticle manufacturing method according to the first aspect.

[0045] The temperature of the above pyrolysis reactor is 700°C to 1,000°C, and the temperature can be gradiented so that the temperature at the top of the pyrolysis reactor is higher than the temperature at the bottom of the reactor.

[0046] In the volume of the above pyrolysis reactor, the volume of the turbulent region: the volume of the laminar region can be 1:9 to 9:1.

[0047] The above silicon microparticles have a crystal grain size of 40 nm or less and an average particle diameter (D 50 ) is 100 nm to 10 ㎛, and the sphericity can be 80% or more.

[0048] According to a third aspect of the present invention, it is possible to provide silicon microparticles manufactured according to the method for manufacturing silicon microparticles according to the first aspect of the present invention.

[0049] The above silicon microparticles have an average crystal grain size of 40 nm or less, an average particle diameter (D50) of 100 nm to 10 ㎛, and a sphericity of 80% or more.

[0050] According to the present invention, silicon microparticles having a crystal grain size of 40 nm or less and a sphericity of 80% or more can be provided.

[0051] The method for manufacturing silicon microparticles according to the present invention can manufacture silicon microparticles while directly controlling the crystal grain size and sphericity without processes such as crushing and sorting after manufacturing polysilicon particles.

[0052] The method for producing silicon microparticles according to the present invention has the advantages of being economical and efficient and suitable for mass production, as silicon microparticles can be directly produced by simultaneously producing silicon seeds and growing silicon particles in a single reactor without requiring the input of silicon rods and seeds.

[0053] In addition to the effects described above, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

[0054] FIG. 1 is a flowchart schematically illustrating a method for manufacturing silicon microparticles according to one embodiment of the present invention.

[0055] FIG. 2 schematically illustrates a cross-sectional view of a silicon microparticle manufacturing device according to one embodiment of the present invention.

[0056] Figure 3 schematically illustrates a thermal decomposition reactor of a silicon microparticle manufacturing device according to one embodiment of the present invention.

[0057] FIG. 4 shows a visualized simulation of the gas residence time distribution inside a thermal decomposition reactor of a silicon microparticle manufacturing device according to one embodiment of the present invention.

[0058] FIG. 5 is a visualized simulation showing the gas flow rate distribution inside a thermal decomposition reactor of a silicon microparticle manufacturing device according to one embodiment of the present invention.

[0059] Figure 6 visualizes the temperature gradient at the top and bottom of the reactor controlled according to Example 1 of the present invention.

[0060] Figure 7 shows an SEM image photograph of microparticles manufactured according to Example 1 of the present invention.

[0061] Figure 8 shows an SEM image photograph of microparticles manufactured according to Example 2 of the present invention.

[0062] Figure 9 shows an SEM image photograph of microparticles manufactured according to Example 3 of the present invention.

[0063] Figure 10 shows an SEM image photograph of microparticles manufactured according to Example 4 of the present invention.

[0064] Figure 11 shows an SEM image photograph of microparticles manufactured according to Example 5 of the present invention.

[0065] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Like reference numerals designate like elements throughout the specification.

[0066] Any details not described in this specification that can be sufficiently technically inferred by a person skilled in the art will be omitted.

[0067] Although terms like "first" and "second" are used herein to describe various components, these components are not limited by these terms. These terms are used only to distinguish one component from another, and unless otherwise specified, a first component may also be a second component.

[0068] Unless otherwise specifically stated in this specification, each component may be singular or plural.

[0069] In this specification, the phrase "any component is disposed "on (or below)" a component or "on (or below)" a component may mean not only that any component is disposed in contact with the upper surface (or lower surface) of said component, but also that another component may be interposed between said component and any component disposed on (or below) said component.

[0070] When it is described herein that a component is “connected,” “coupled,” or “connected” to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be “interposed” between the components, or that each component may be “connected,” “coupled,” or “connected” through another component.

[0071] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "contains," "includes," and "consists of" should not necessarily be construed to include all components or steps described in the specification, and should be construed to mean that some of the components or steps may not be included, or that additional components or steps may be included.

[0072] When the specification refers to “A and / or B”, it means A, B or A and B, unless otherwise stated, and when the specification refers to “C to D or C~D”, it means C or more and D or less, unless otherwise stated.

[0073] In this specification, when the ratio of the first component and the second component is described as a:b to c:d, it means that “first component: second component = a:b” or “first component: second component = c:d”.

[0074] In this specification, “average grain size” is measured using XRD (Panalytical, Empyrean XRD).

[0075] In this specification, "average particle diameter (D 50)" was measured by the laser diffraction method using a laser diffraction particle size analyzer (LS13 320, Beckman Coulter).

[0076] In this specification, “sphericity” is a value that specifies the horizontal and vertical axes to intersect at 90° from the center of the silicon particle, and converts the length of the vertical axis to the length of the horizontal axis within the particle into a percentage.

[0077] In this specification, microparticles have an average particle diameter (D 50 ) means 100 nm to 10 ㎛, and may include a margin of error.

[0078] Unless otherwise specifically stated herein, “reactor” shall be interpreted to mean “pyrolysis reactor.”

[0079]

[0080] Hereinafter, the present invention will be described in detail.

[0081] Method for manufacturing silicon microparticles

[0082] A method for manufacturing silicon microparticles of the present invention is described with reference to FIG. 1.

[0083] The method for manufacturing silicon microparticles according to the present invention is characterized in that the average crystal grain size is 40 nm or less and the average particle diameter (D 50 ) is for manufacturing silicon microparticles having a size of 100 nm to 10 ㎛ and a sphericity of 80% or more.

[0084] (S1) A step of introducing a silicon source gas mixture containing two or more silicon source gases having different decomposition temperatures and hydrogen gas into a reactor;

[0085] (S2) a step of decomposing a silicon source gas mixture in the reactor to generate silicon microparticles;

[0086] The silicon source gas mixture is a gas that serves as a raw material for manufacturing silicon particles, and according to one embodiment of the present invention, it may be a mixture of two or more types selected from the silicon source gases represented by Chemical Formula 1 or Chemical Formula 2.

[0087] [Chemical Formula 1] SiH x Cl 4-x (x is an integer from 0 to 4)

[0088] [Chemical Formula 2] Si2H y Cl 6-y (y is an integer from 0 to 6)

[0089] According to one embodiment of the present invention, the silicon source gas represented by the chemical formula 1 or 2 may be selected from monosilane (SiH4) gas, dichlorosilane (SiH2Cl2) gas, trichlorosilane (SiHCl3) gas, tetrachlorosilane (SiCl4) gas, dichlorosilane hexachlorosilane (Si2Cl6) gas, and disilane (Si2H6) gas, but is not limited thereto.

[0090] The silicon source gas mixture of the present invention comprises a first silicon source gas and a second silicon source gas, wherein the first silicon source gas and the second silicon source gas can be selected from the silicon source gases represented by the chemical formula 1 or chemical formula 2.

[0091] According to one embodiment of the present invention, the decomposition temperature of the first silicon source gas is lower than the decomposition temperature of the second silicon source gas, and the decomposition temperature of the first silicon source gas is lower than the decomposition temperature of the second silicon source gas, and the decomposition temperature of the first silicon source gas may be 350°C to 600°C, and the decomposition temperature of the second silicon source gas may be 600°C to 1,000°C. At this time, the decomposition temperatures of the first silicon source gas and the second silicon source gas are not the same. As a specific example, the first silicon source gas may be dichlorosilane (SiH2Cl2) gas, and the second silicon source gas may be trichlorosilane (SiHCl3) gas.

[0092] As in the present invention, when a method for manufacturing silicon microparticles uses a mixture of silicon source gases having different decomposition temperatures, the silicon source gas having a lower decomposition temperature first forms silicon seed particles, and simultaneously or continuously grows the formed seed particles to manufacture silicon microparticles. Specifically, the decomposition temperature of the first silicon source gas is lower than the decomposition temperature of the second silicon source gas, so that the first silicon source gas can first be thermally decomposed to form seed particles within the reactor. In addition, the second silicon source gas can be thermally decomposed and deposited onto the seed particles formed, thereby manufacturing silicon microparticles in one reactor.

[0093] In this way, the method for manufacturing silicon microparticles according to the present invention does not require separate input of silicon rods or silicon seed particles, and does not require a process of contacting a reactor during production, so the content of metal impurities is low and the purity is high, and micro-sized silicon particles can be efficiently manufactured without a separate grinding process or particle size selection process.

[0094] The first silicon source gas and the second silicon source gas introduced into the reactor may be introduced at a molar ratio of, for example, 1:0.2 to 1:6, and may be introduced at a molar ratio of, for example, 1:0.5 to 1:4. The introduction ratio of the first silicon source gas and the second silicon source gas may be specified to control the formation speed of seed particles and the growth of particles. For example, when the ratio of the first silicon source gas is less than the above range, silicon seed particles may not be formed smoothly, and when the ratio of the first silicon source gas exceeds the above range, only a large amount of small-sized particles that have not grown sufficiently may be formed, which may cause a problem in that silicon particles of a desired size cannot be formed.

[0095] In the method for manufacturing silicon microparticles of the present invention, hydrogen (H2) gas, which is a growth reaction gas, is introduced together with a silicon source gas mixture. The introduced hydrogen gas undergoes a reduction reaction with the silicon source gas mixture, thereby enabling the growth of silicon particles.

[0096] The silicon source gas mixture and hydrogen gas introduced into the reactor may be introduced at a molar ratio of, for example, 1:0.5 to 1:10, for example, 1:1 to 1:5, for example, 1:2 to 1:3. If the injection ratio of hydrogen gas is less than the above range, the growth reaction may not occur well, and if the injection ratio of hydrogen gas exceeds the above range, the silicon source gas mixture is relatively small, so there is a limit to producing the desired amount of silicon particles.

[0097] The method for producing silicon microparticles of the present invention comprises the step (S2) of decomposing a silicon source gas mixture in the thermal decomposition reactor to produce silicon microparticles. In one reactor, the silicon source gas mixture can be decomposed to produce silicon seed particles while simultaneously growing to produce silicon microparticles.

[0098] Specifically, in the silicon source gas mixture introduced into the reactor, the first silicon source gas having a lower decomposition temperature is first thermally decomposed to form seed particles, and at the same time, the second silicon source gas is thermally decomposed to form seed particles, thereby allowing silicon microparticles to be manufactured using chemical vapor synthesis (CVS).

[0099] Accordingly, silicon microparticles can be manufactured at a faster rate, and high-purity silicon microparticles can be manufactured without the need for separate crushing and sorting processes.

[0100] In the present invention, when the silicon source gas mixture is decomposed to produce silicon microparticles, the internal temperature of the reactor may be 700°C to 1,000°C, and the temperature at the top of the reactor may be gradiently increased to be higher than the temperature at the bottom of the reactor. Details regarding the reactor will be described in detail below in the section on the apparatus for producing silicon microparticles.

[0101] The internal pressure of the reactor may be 1 bar to 10 bar. In the reaction step, it may be desirable for the reactor to have the temperature and pressure in the above range from the viewpoints of controlling the thermal decomposition rate of the silicon source gas mixture, controlling the size of silicon particles, and improving the reaction yield. The internal temperature of the reactor is preferably equal to or slightly higher than the thermal decomposition temperature of the second silicon source gas, which has a high decomposition temperature, since thermal decomposition must occur, and the pressure may be controlled according to process conditions. The reactor may be heated to the above temperature by a heating device.

[0102] According to one embodiment of the present invention, the time for the silicon source gas mixture to produce silicon microparticles in the reactor may be approximately 5 minutes to 3 hours, but this may be appropriately adjusted depending on the size of the reactor, the amount of raw material gas introduced, and the desired production amount. However, if the reaction time of the silicon source gas mixture is too short, there may be a problem that there is not enough time for seed particles to form and the particles to grow, and if the reaction time of the silicon source gas mixture is too long, the size of the silicon particles may go beyond the desired range, and there may be a problem that the crystal grains of the silicon particles overgrow, causing the crystal grain size to become too large.

[0103] According to one embodiment of the present invention, the method for producing silicon microparticles may further include a step of recovering the produced silicon microparticles, and may further include a step of cooling them prior to recovery.

[0104] According to one embodiment of the present invention, a carrier gas may be additionally introduced into the reactor. For example, the carrier gas may be argon (Ar) gas or nitrogen (N2) gas. The carrier gas may be introduced to maintain the flow rate of the gas injected from the bottom of the reactor. Since the reactor according to the present invention has a structure in which gas is introduced from the bottom, a carrier gas may be used to easily control the flow rate of the gas.

[0105] According to another aspect of the present invention, silicon microparticles manufactured according to the above-described method for manufacturing silicon microparticles are provided. The silicon microparticles manufactured in this manner can be used as silicon nitride raw materials, solar cell materials, secondary battery negative electrode materials, and the like.

[0106] Specifically, the silicon particles manufactured according to the present invention have an average particle diameter (D 50 ) may be, for example, 100 nm to 10 ㎛, for example, 1 ㎛ to 5 ㎛, for example, 1.5 ㎛ to 3 ㎛. Accordingly, a separate grinding process is not required, and since there is no grinding process, there is no generation of fine powder, and a sieving process is also not required, so the content of metal impurities is also significantly low. The silicon microparticles of the present invention having a particle size distribution in the above range can contribute to improving the lifespan and capacity retention rate of a secondary battery when used as a secondary battery negative electrode material.

[0107] In addition, the silicon microparticles manufactured in the present invention may have smaller crystal grains than in the past. The larger the crystal grain size of the silicon particles, the lower the life characteristics of the secondary battery when used as an anode material of the secondary battery. The crystal grain size of the silicon particles used in the past is approximately 100 nm. Therefore, according to one embodiment of the present invention, the average crystal grain size of the silicon microparticles may be 40 nm or less, and by controlling the process conditions, for example, silicon microparticles having an average crystal grain size of 30 nm or less, for example, silicon microparticles having an average crystal grain size of 25 nm or less, may be manufactured. When the crystal grain size is reduced in this way, particle destruction due to volume change that occurs during charging and discharging of the secondary battery is reduced, thereby contributing to improving the lifespan of the secondary battery.

[0108] In addition, the silicon microparticles produced in the present invention can exhibit very high sphericity because there is no pulverization process, unlike microparticles obtained by conventional pulverization. When non-spherical silicon particles are used as an anode material of a secondary battery, there is a problem that the dispersibility is low and the probability of side reactions occurring during the charge / discharge process of the secondary battery is high, which ultimately lowers the performance of the secondary battery. Therefore, when the spherical silicon microparticles according to the present invention are used as an anode material of a secondary battery, they can contribute to improving the performance of the secondary battery. According to one embodiment of the present invention, the silicon microparticles may have, for example, a sphericity of 80% or more, for example, a sphericity of 90% or more, for example, a sphericity of 95% or more, for example, a sphericity of 99% or more.

[0109] Silicon microparticle manufacturing device

[0110] Referring to FIG. 2, a silicon microparticle manufacturing device for implementing the method for manufacturing silicon microparticles of the present invention can be provided.

[0111] The above silicon microparticle manufacturing device (100) includes a raw material gas injection unit (10); a raw material gas mixing unit (20); a pyrolysis reactor (30); a heating unit (40) surrounding the reactor; and a gas discharge unit (50). The pyrolysis reactor (30) is characterized in that it includes an internal structure (60), thereby simultaneously forming a turbulent flow region and a laminar flow region during a reaction.

[0112] The above pyrolysis reactor (30) can be used without limitation as long as it is a reactor capable of implementing chemical vapor synthesis (CVS).

[0113] The above thermal decomposition reactor (30) may be a reactor used in the method for producing silicon microparticles of the present invention.

[0114] For example, the pyrolysis reactor (30) can be used among a chemical vapor deposition reactor, a chemical vapor condensation reactor, and a fluidized-bed reactor, and preferably, a chemical vapor deposition reactor is used.

[0115] The above internal structure (60) is a structure in which both the upper and lower parts are open, and may have a cylindrical structure, a hexahedral structure, etc. depending on the structure of the pyrolysis reactor (30), and may have the same shape as the shape of the pyrolysis reactor (30), but is not necessarily limited thereto.

[0116] The heating unit (40) surrounding the pyrolysis reactor (30) is not particularly limited as long as it is a heating unit applicable in the present technical field, and it is required to be able to heat to a temperature of 700°C to 1000°C, which is the temperature required in the present invention. For example, it can be operated in a manner in which a heating wire is inserted into the wall of the pyrolysis reactor (30) and power is applied to heat it, or in a manner in which a tube-shaped furnace formed around the pyrolysis reactor (30) is provided to heat it.

[0117] In addition, as described later, since the temperatures of the upper part (30a) and the lower part (30b) of the pyrolysis reactor (30) are different, it is preferable that the heating part (40) be designed so that the temperatures of the upper part (30a) and the lower part (30b) can be controlled differently.

[0118] Although not shown in Fig. 2, it may include a bag filter, various pressure and temperature controllers, valves, etc. for capturing the final silicon microparticles.

[0119] Referring to FIG. 3, reaction gases are each supplied to the raw material gas injection unit (10), and reaction gases (raw material gases) supplied from the raw material gas mixing device (20) are mixed and injected into the pyrolysis reactor (30) through the internal structure (60).

[0120] The arrow marked "IN" in Fig. 3 indicates the injection direction in which the raw material gas moves from the raw material gas injection portion (10) to the internal structure (60) together with the pyrolysis reactor (30). The raw material gas injected through the internal structure (60) passes through the upper part of the internal structure (60) and is diffusely injected into the pyrolysis reactor (30).

[0121] The arrow marked “OUT” in Fig. 3 indicates the direction in which gas is discharged to the gas discharge unit (50) after the reaction proceeds in the pyrolysis reactor (30) including the internal structure (60).

[0122] Although not specifically illustrated in the drawing, according to one embodiment of the present invention, it is also possible to design the feed gas flow direction and the gas discharge direction in FIG. 3 to be opposite each other. Referring to FIG. 3, this means that the feed gas can be designed to be supplied at the location of the gas discharge unit (50) and the gas can be discharged at the location of the feed gas injection unit (20). This can be changed by changing the flow of gas inside and outside the reactor.

[0123] According to a preferred embodiment of the present invention, as shown in FIG. 3, one raw material gas injection part (10) is provided on the central side of the internal structure (60), and two gas discharge parts (50) are provided on the outer side of the pyrolysis reactor (30) that is not occupied by the internal structure (60).

[0124] The above pyrolysis reactor (30) is characterized in that a turbulent flow region is formed at the top and a laminar flow region is formed at the bottom of the pyrolysis reactor (30).

[0125] In addition, the above pyrolysis reactor (30) is characterized by controlling the upper and lower temperatures differently.

[0126] Specifically, the area from the raw material gas injection portion (10) to approximately 1 / 3 of the height of the pyrolysis reactor (30) is designated as the lower portion (30a), and the area from that point to the top of the reactor is designated as the upper portion (30b), and the temperature of the upper portion (30b) is set to be about 50 to 100°C higher than the temperature of the lower portion (30a).

[0127] According to one embodiment of the present invention, the temperature of the lower part (30a) of the pyrolysis reactor may be approximately 700°C to 1000°C, and may be 800°C to 900°C. Accordingly, the temperature of the lower part (30b) of the pyrolysis reactor may be heated to a temperature as high as 50°C to 100°C.

[0128] As a result, in the lower part (30a) of the pyrolysis reactor where the temperature is set relatively low, the silicon seed production reaction mainly proceeds with the silicon source gas having a relatively low pyrolysis temperature.

[0129] Additionally, in the upper part (30b) of the pyrolysis reactor where the temperature is set relatively high, silicon seeds generated in the lower part (30a) are grown into particles by a chemical vapor deposition reaction using silicon sources having a relatively high pyrolysis temperature, thereby forming micro-level silicon particles.

[0130] What is important is that, as described in detail below, a laminar flow region is formed predominantly in the lower part (30a) of the pyrolysis reactor, and a turbulent flow region is formed predominantly in the upper part (30b), so that the seed generation reaction can proceed mainly in the lower part (30a) and the chemical deposition reaction can proceed mainly in the upper part (30b) as intended in the present invention, thereby exhibiting high efficiency and controllability in producing silicon microparticles.

[0131] The turbulent flow region and the laminar flow region are described in detail with reference to FIGS. 4 and 5.

[0132] Figure 4 is a simulation drawing visualizing the flow of gas in the upper part of the reactor as a line, and is represented by a color spectrum distinguished according to the gas residence time (particle residence time, Particle RT).

[0133] Since blue represents a residence time of 0, the closer to blue the color, the shorter the residence time of the gas particles. A short residence time of gas particles indicates a linear flow, meaning that they are quickly discharged from the reactor, indicating the development of laminar flow.

[0134] Conversely, a color shift toward red indicates a longer residence time. A longer residence time for gas particles indicates that the reaction gas injected from the bottom of the reactor remains mixed at the top, indicating the development of turbulence.

[0135] As shown in FIGS. 4a to 4d, the cross-sectional diameter of the internal structure (60) remains the same, but the height of the internal structure (60) relative to the height of the pyrolysis reactor (30) gradually decreases. In other words, the occupancy rate of the turbulent region where flow does not develop in the upper part of the reactor can be adjusted depending on the height of the internal structure.

[0136] That is, Fig. 4 shows that the height of the internal structure (60) is set as a factor for controlling the volume of the turbulent region and the laminar region formed according to the residence time of gas particles, and that by designing the height of the internal structure (60) differently compared to the height of the pyrolysis reactor (30), the volume of the turbulent region where no flow develops in the upper part of the reactor can be controlled.

[0137] The laminar flow region is suitable for seed formation, and the turbulent flow region is suitable for particle growth. Therefore, by adjusting factors such as the height of the internal structure (60), an optimal combination of the volumes of the laminar flow region and the turbulent flow region can be derived.

[0138] Figure 5 is a simulation diagram visualizing the gas flow velocity (vector value) at the top of the reactor as the direction and length of the arrows. The color spectrum is distinguished according to the gas flow velocity. Bluer colors indicate slower flow velocity, and redder colors indicate faster flow velocity.

[0139] The interpretation of Fig. 5 is the same as the interpretation of Fig. 4 described above. That is, the more or shorter the blue arrows, the laminar flow region in which the gas particle residence time in the corresponding region is short, and the more or longer the arrows approaching red, the turbulent flow region in which the flow in the corresponding region is not active, the longer the gas particle residence time, and the more mixing there is.

[0140] FIGS. 5a to 5d are simulations of the same reactor as FIGS. 4a to 4d, and it can be confirmed in the flow velocity analysis that the occupancy rate of the turbulent region where flow does not develop in the upper part of the reactor can be controlled depending on the height of the internal structure. In this way, by controlling the design of the internal structure (60), the volume and residence time of the turbulent region formed in the upper part (30b) of the pyrolysis reactor can be controlled, and as a result, the size and growth of the silicon particles to be finally manufactured can be controlled.

[0141] According to one embodiment of the present invention, the volume of the turbulent region: the volume of the laminar region in the volume of the pyrolysis reactor may be, for example, 1:9 to 9:1, for example, 2:8 to 8:2, for example, 3:7 to 7:3, for example, 4:6 to 6:4, for example, 5:5.

[0142] According to one embodiment of the present invention, the material of the internal structure (60) has heat resistance of 700 to 1000°C and may include at least one selected from graphite, quartz, and ceramic. By controlling the ratio of the diameter of the pyrolysis reactor (30) and the diameter of the internal structure (60) and the height of the reactor and the height of the internal structure, the turbulent flow region and the laminar flow region can be designed with a desired volume ratio, and the method thereof is not particularly limited.

[0143] Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

[0144] Example 1

[0145] The reactor was pressurized to a pressure of 0.5 bar, and heated so that the temperature at the bottom of the reactor was 800°C and the temperature at the top of the reactor was 900°C.

[0146] After that, monosilane (SiH4, decomposition temperature of about 600°C) as a first silicon source gas, trichlorosilane (SiHCl3, decomposition temperature of about 800°C) as a second silicon source gas, and hydrogen gas were mixed in a molar ratio of 0.5:1:3, and the first silicon source gas, the second silicon source gas, and the hydrogen gas were all introduced into the reactor. The amount of trichlorosilane introduced was 2056 sccm based on the amount introduced.

[0147] Then, the reaction was carried out in a reactor for approximately 60 minutes to carry out a thermal decomposition reaction, thereby producing micro-sized silicon particles. The produced silicon particles were cooled and recovered.

[0148] Example 2

[0149] Pressurization and heating were performed in the same manner as in Example 1, but the temperature conditions of the reactor were changed to those described in Table 1 below. Thereafter, monosilane (SiH4, decomposition temperature of about 600°C) as the first silicon source gas, trichlorosilane (SiHCl3, decomposition temperature of about 800°C) as the second silicon source gas, and hydrogen gas were mixed in a molar ratio of 0.5:1:1.6, and the first silicon source gas, the second silicon source gas, and the hydrogen gas were all introduced into the reactor. The amount of trichlorosilane introduced was 4134 sccm based on the amount introduced.

[0150] Then, the reaction was carried out in a reactor for approximately 45 minutes to carry out a thermal decomposition reaction, thereby producing micro-sized silicon particles. The produced silicon particles were cooled and recovered.

[0151] Example 3

[0152] Pressurization and heating were performed in the same manner as in Example 1, but the temperature conditions of the reactor were changed to those described in Table 1 below. Thereafter, monosilane (SiH4, decomposition temperature of about 600°C) as the first silicon source gas, trichlorosilane (SiHCl3, decomposition temperature of about 800°C) as the second silicon source gas, and hydrogen gas were mixed in a molar ratio of 0.5:1:3, and the first silicon source gas, the second silicon source gas, and the hydrogen gas were all introduced into the reactor. The amount of trichlorosilane introduced was 4961 sccm based on the amount introduced.

[0153] Then, the reaction was carried out in a reactor for approximately 35 minutes to carry out a thermal decomposition reaction, thereby producing micro-sized silicon particles. The produced silicon particles were cooled and recovered.

[0154] Example 4

[0155] Pressurization and heating were performed in the same manner as in Example 1, but the temperature conditions of the reactor were changed to those described in Table 1 below. Thereafter, monosilane (SiH4, decomposition temperature of about 600°C) as the first silicon source gas, trichlorosilane (SiHCl3, decomposition temperature of about 800°C) as the second silicon source gas, and hydrogen gas were mixed in a molar ratio of 0.5:1:3, and the first silicon source gas, the second silicon source gas, and the hydrogen gas were all introduced into the reactor. The amount of trichlorosilane introduced was 2756 sccm based on the amount introduced.

[0156] Then, the reaction was carried out in a reactor for approximately 60 minutes to carry out a thermal decomposition reaction, thereby producing micro-sized silicon particles. The produced silicon particles were cooled and recovered.

[0157] Example 5

[0158] Pressurization and heating were performed in the same manner as in Example 1, but the temperature conditions of the reactor were changed to those described in Table 1 below. Thereafter, monosilane (SiH4, decomposition temperature of about 600°C) as the first silicon source gas, trichlorosilane (SiHCl3, decomposition temperature of about 800°C) as the second silicon source gas, and hydrogen gas were mixed in a molar ratio of 0.5:1:3, and the first silicon source gas, the second silicon source gas, and the hydrogen gas were all introduced into the reactor. The amount of trichlorosilane introduced was 3859 sccm based on the amount introduced.

[0159] Then, the reaction was carried out in a reactor for approximately 60 minutes to carry out a thermal decomposition reaction, thereby producing micro-sized silicon particles. The produced silicon particles were cooled and recovered.

[0160] Experimental example

[0161] SEM images of the silicon particles manufactured in Examples 1 to 5 are shown in Figures 7 to 11, respectively.

[0162] D using a laser diffraction particle size analyzer (LS13 320, Beckman Coulter) 50 was measured.

[0163] The average crystal grain size of silicon particles was measured by analyzing according to the X-ray diffraction method using XRD (Panalytical, Empyrean XRD).

[0164] By analyzing the SEM images of Figures 7 to 11, 20 particles were randomly selected, the sphericity was measured, and the average value was calculated to determine the sphericity value.

[0165] Process conditions of Examples 1 to 5 and the measured D 50 , the average grain size and sphericity are shown in Table 1 below.

[0166] Example 1 Example 2 Example 3 Example 4 Example 5 Reactor bottom temperature (℃) 800 800 800 800 850 Reactor top temperature (℃) 900 900 900 850 900 TCS input (sccm) 20 5 6 4 3 1 6 4 9 6 1 2 7 5 6 3 8 5 9 SiH4: TCS: Hydrogen (molar ratio) 0.5:1:3.0 0.5:1:1.6 0.5:1:3.0 0.5:1:3.0 0.5:1:3.0 Retention time (sec) 143 10 9 5 1.8 1238 5 Process time (min) 60 45 35 60 60 D 50 (㎛)2.481.802.482.652.30Average grain size (nm)2530232531Sphericity (%)8387908892

[0167] The meanings of the terms used in Table 1 above are as follows.

[0168] “TCS” stands for trichlorosilane (SiHCl3).

[0169] "sccm" is standard cubic centimeter per minute (based on 0℃ and 1atm), and is a unit of flow rate per unit time.

[0170] “Retention time” refers to the time it takes for the reaction gas to leave the reactor after it has been injected into it.

[0171] “Process time” refers to the time required for the deposition reaction to complete.

[0172] As can be seen in Table 1 above, the silicon particles manufactured according to the present invention were able to achieve the desired micro-level particle size (D50) and crystal grain size, and exhibited extremely high sphericity. Furthermore, the manufacturing method of the present invention demonstrated excellent processability in that it could be efficiently manufactured through chemical vapor synthesis (CVS) without a separate grinding process.

[0173]

[0174] Although the present specification has been described in more detail with reference to the embodiments and drawings, the present specification is not necessarily limited to these embodiments and drawings, and various modifications may be implemented without departing from the technical spirit of the present specification. Therefore, the embodiments disclosed in the present specification are not intended to limit the technical spirit of the present invention, but to explain it, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all aspects and not restrictive. The protection scope of the present specification and the present invention should be interpreted by the claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of rights of the present specification and the present invention.

Claims

1. (S1) A step of introducing a silicon source gas mixture containing two or more silicon source gases having different decomposition temperatures and hydrogen gas into a reactor; (S2) a step of decomposing a silicon source gas mixture in the reactor to generate silicon microparticles; The above-mentioned generated silicon microparticles have an average crystal grain size of 40 nm or less and an average particle diameter (D 50 ) is 100 nm to 10 ㎛ and has a sphericity of 80% or more. Method for manufacturing silicon microparticles.

2. In paragraph 1, A method for producing silicon microparticles, wherein the silicon source gas mixture is a mixture of two or more silicon source gases selected from the following chemical formula 1 or chemical formula 2. [Chemical Formula 1] SiH x Cl 4-x (x is an integer from 0 to 4) [Chemical Formula 2] Si2H y Cl 6-y (y is an integer from 0 to 6) 3. In paragraph 2, The silicon source gas represented by the above chemical formula 1 or 2 is selected from monosilane (SiH4) gas, dichlorosilane (SiH2Cl2) gas, trichlorosilane (SiHCl3) gas, tetrachlorosilane (SiCl4) gas, dichlorosilane hexachlorosilane (Si2Cl6) gas, and disilane (Si2H6) gas. Method for manufacturing silicon microparticles.

4. In paragraph 1, The above silicon source gas mixture includes a first silicon source gas and a second silicon source gas, and the decomposition temperature of the first silicon source gas is lower than the decomposition temperature of the second silicon source gas. Method for manufacturing silicon microparticles.

5. In paragraph 4, The decomposition temperature of the first silicon source gas is 350°C to 600°C, The decomposition temperature of the second silicon source gas is 600°C to 1000°C. Method for manufacturing silicon microparticles.

6. In paragraph 4, The first silicon source gas and the second silicon source gas are introduced in a molar ratio of 1:0.2 to 1:

6. Method for manufacturing silicon microparticles.

7. In paragraph 4, The above silicon source gas mixture and hydrogen gas are introduced in a molar ratio of 1:0.5 to 1:

10. Method for manufacturing silicon microparticles.

8. In paragraph 1, The temperature of the above reactor is 700℃ to 1,000℃, The temperature at the top of the reactor is gradiented so as to be higher than the temperature at the bottom of the reactor. Method for manufacturing silicon microparticles.

9. In paragraph 1, In the above reactor, the generation of silicon seeds and the growth of silicon particles from the continuously generated silicon seeds are simultaneously performed. Method for manufacturing silicon microparticles.

10. In paragraph 1, In the step (S2), the reaction time of the silicon source gas mixture in the reactor for producing silicon microparticles is 5 minutes to 3 hours. Method for manufacturing silicon microparticles.

11. In paragraph 1, Injecting additional carrier gas into the above reactor, Method for manufacturing silicon microparticles.

12. Raw gas injection section; Raw gas mixing device; pyrolysis reactor; a heating element surrounding the above reactor; and Including a gas discharge part, The above pyrolysis reactor is a pyrolysis reactor in which a turbulent flow region formed at the upper part of the pyrolysis reactor and a laminar flow region formed at the lower part of the pyrolysis reactor coexist. A device for manufacturing silicon microparticles.

13. In paragraph 12, An internal structure forming a turbulent flow region and a laminar flow region is included inside the above pyrolysis reactor, The material of the internal structure has a heat resistance of 700°C to 1000°C and includes at least one selected from graphite, quartz and ceramic. A device for manufacturing silicon microparticles.

14. In paragraph 12, The temperature of the above pyrolysis reactor is 700℃ to 1,000℃, The temperature at the top of the above pyrolysis reactor is gradiented so that it is higher than the temperature at the bottom of the reactor. A device for manufacturing silicon microparticles.

15. In paragraph 12, In the volume of the above pyrolysis reactor, the volume of the turbulent region: the volume of the laminar region is 1:9 to 9:1, A device for manufacturing silicon microparticles.

16. In paragraph 12, The above silicon microparticles have a crystal grain size of 40 nm or less and an average particle diameter (D 50 ) is 100 nm to 10 ㎛ and has a sphericity of 80% or more. A device for manufacturing silicon microparticles.

17. Silicon microparticles manufactured according to the method for manufacturing silicon microparticles according to any one of claims 1 to 11.

18. In paragraph 17, The above silicon microparticles have an average crystal grain size of 40 nm or less, an average particle diameter (D50) of 100 nm to 10 ㎛, and a sphericity of 80% or more. Silicon microparticles.

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