KR102550755B1 - A method for manufacturing silicon powder for secondary battery and silicon powder - Google Patents

Abstract

The present invention is to prepare silicon powder of a size and shape suitable for a secondary battery active material from a silicon mass,
Obtaining a first powder by crushing the silicon lump to an average particle diameter (D50) of 100um to 1000um;
obtaining a second powder by pulverizing the first powder to a size of 10 um to 200 um;
Obtaining a third powder by pulverizing the second powder to a size of 1 um to 100 um;
Obtaining a fourth powder by removing particles larger than 25um to 45um from the third powder;
Obtaining a fifth powder by removing particles smaller than 1 μm from the fourth powder;
It provides a method for manufacturing silicon powder for a secondary battery and a silicon powder for a secondary battery comprising a.

Description

Manufacturing method of silicon powder for secondary batteries and silicon powder manufactured using the same

The present invention relates to a method for producing silicon powder for a secondary battery and a silicon powder manufactured using the same, and in detail, a method for manufacturing silicon powder usable as a negative active material for a secondary battery from a lump of silicon and silicon produced by the method It is an invention about powder.

A lithium secondary battery consists of a positive electrode, a negative electrode, a separator, and an electrolyte. Among them, the negative electrode is composed of an active material involved in a battery reaction, a binder, and a conductive material, and the active material is carbon such as natural graphite, artificial graphite, and amorphous carbon. Manufactured by combining silicon-based materials, such as silicon powder, silicon thin film, silicon alloy, nano-silicon wire, and silicon oxide (SiOx, 0<x<2), metal-based materials such as tin and titanium, and materials containing graphite and silicon A composite anode active material material may be used. The negative electrode active material is a material capable of accepting and storing lithium during charging of the secondary battery and releasing lithium during discharging. Lithium ion batteries developed in the 1990s mainly use graphite as an anode active material, and as disclosed in Korean Registered Patent No. 10-2085938 and Korean Patent Publication No. 10-2011-0065133, in order to increase charge and discharge capacity, lithium ion occluding ability such as silicon is used. A silicon-carbon composite anode material in which a large material is added to or combined with a graphite or carbonaceous active material is used.

Silicon has a theoretical capacity of 4200 mAh/g, more than 10 times greater than graphite's theoretical specific capacity of 372 mAh/g. However, expansion and contraction occur repeatedly during the charging and discharging process, and deformation and fragmentation proceed accordingly, so that the electrical connection is broken between particles or between particles and the current collector, and the solid electrolyte interface continues to increase on the surface of the silicon particles, depleting the electrolyte lithium. There is a problem in that the internal resistance of the battery is increased and the battery performance is deteriorated.

로 냉각된 기판 위에 증착시켜 실리콘 입자를 수득한다.As a means to solve this problem, a method of reducing the size of silicon particles to a size of several to several tens of nanometers (nm) is disclosed in US Patent US8734991. In this method, 20 to 100 nm polycrystalline silicon particles are produced with monosilane or trichlorosilane, or dichlorosilane. Another US patent US9099717 discloses polycrystalline silicon particles having a size of 20 to 100 nm. Here, metal silicon is vaporized with an electron beam and 300 to 800

deposited on a substrate cooled by , to obtain silicon particles.

When the silicon particle size is reduced in this way, the absolute value of the size of expansion and contraction during charging and discharging is reduced compared to the case where the particle size is large, and thus the effect of expansion and contraction on battery performance can be reduced. However, the method of making silicon particles using an expensive silicon-containing special gas as a raw material in order to make small silicon particles is difficult to industrially use due to high manufacturing cost and difficult mass production.

Korean Registered Patent No. 10-2085938 Republic of Korea Patent Publication 10-2011-0065133

The present invention is an invention to solve the above-described problems, and manufactures a silicon powder for a secondary battery capable of improving charge and discharge capacity and efficiency by controlling the particle size distribution of the silicon powder for a secondary battery within a predetermined range according to the experimental results of the present invention. A method and a silicon powder prepared using the same are provided.

A method for producing silicon powder for a secondary battery according to an embodiment of the present invention includes the steps of crushing a silicon lump to have an average particle diameter (D50) of 100 um to 1000 um to obtain a first powder, the first powder having an average particle diameter of 10 um to 200 um Grinding to obtain a second powder, obtaining a third powder by pulverizing the second powder to an average particle size of 1 um to 100 um, removing particles larger than 25 um to 45 um from the third powder to obtain a fourth obtaining a powder; and obtaining a fifth powder by classifying the fourth powder such that a ratio of particles smaller than 1 μm in the fourth powder is equal to or less than a predetermined value.

In the method for manufacturing silicon powder for a secondary battery according to an embodiment of the present invention, the step of obtaining the fifth powder is to classify the fourth powder so that the ratio of particles smaller than 1 μm in the fourth powder is 15% or less. can do.

In the method of manufacturing silicon powder for a secondary battery according to an embodiment of the present invention, in the step of obtaining the fifth powder, particles smaller than 1 μm may be removed from the fourth powder.

In the method of manufacturing silicon powder for a secondary battery according to an embodiment of the present invention, the silicon mass is metallurgical grade silicon, upgraded metallurgical grade silicon, or polycrystalline silicon, or A polycrystalline silicon ingot, or a polycrystalline wafer, or a single crystal silicon ingot, or a single crystal silicon wafer, and metal silicon or UMG silicon or polysilicon or polysilicon ingot However, polysilicon wafers, single-crystal silicon ingots, or single-crystal silicon wafers may be produced by-products in the form of lumps, plates, or particulates.

In the method of manufacturing silicon powder for a secondary battery according to an embodiment of the present invention, at least one of the step of obtaining the first powder, the step of obtaining the second powder, and the step of obtaining the third powder is crushed or Each step of classifying after grinding may be further included.

In the manufacturing method of silicon powder for a secondary battery according to an embodiment of the present invention, the average particle diameter (D50) of the fifth powder may be 1 um to 10 um.

In the manufacturing method of silicon powder for a secondary battery according to an embodiment of the present invention, the SPAN of the fifth powder may be less than 1. Here, SPAN is defined by the following formula (D10 is the cumulative 10% particle size of the fifth powder, D50 is the cumulative 50% particle size of the fifth powder, and D90 is the cumulative 50% particle size of the fifth powder).

Silicon powder according to an embodiment of the present invention is manufactured by the above-described method for manufacturing silicon powder for a secondary battery.

The present invention relates to a method for producing silicon powder for a secondary battery, and provides a method for producing silicon powder that can be used as a negative electrode active material for a secondary battery by crushing, pulverizing, and finely pulverizing a silicon lump, and the silicon powder thus produced.

Using the silicon powder provided by the present invention, carbon nanotubes, graphene, carbon nanofibers, vapor grown carbon fibers, carbon fibers, If the anode material is composed of a 1-dimensional, 2-dimensional, or 3-dimensional conductive material such as carbon/carbon composite, the existing graphite active material and 0-dimensional conductive material such as carbon black can be used. The charge and discharge capacity is more than 10 times greater than that of the negative electrode material, and the battery charge and discharge speed is faster, making it possible to manufacture a high-capacity secondary battery with high-speed charge and discharge suitable for electric vehicles.

In order to further improve the performance of the negative electrode material using the silicon powder provided by the present invention, an ion-conducting binder may be used in the negative electrode material.

The secondary battery manufactured using the silicon powder provided by the present invention as an active material can be a smaller and lighter battery than when using a conventional graphite anode material, thereby reducing the weight of a battery that accounts for half of the total weight in an electric vehicle. By reducing it, the performance of electric vehicles can be improved. In addition, since the size of the battery is reduced, the utilization of an energy storage system essential for the use of sustainable renewable energy can be increased.

A method of manufacturing silicon powder for a secondary battery according to an embodiment of the present invention and silicon powder having excellent charge/discharge performance can be provided through particle size distribution control.

1 shows a method for manufacturing silicon powder for a secondary battery according to an embodiment of the present invention.
Figure 2 shows the particle size distribution of the silicon powder of the embodiment of the present invention.
3 shows the particle size distribution of Comparative Example.
4 shows life characteristics according to charge/discharge cycles of secondary batteries prepared in Examples and Comparative Examples of the present invention.
5 shows the effect of the silicon powder of less than 1 μm included in the silicon powder on the performance of the secondary battery.
6 shows the aggregation phenomenon of silicon powder.
1 to 6 are presented so as to generally understand the technical idea of the present invention, and the present invention is not limited to FIGS. 1 to 6.

Since the present invention can apply various transformations and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the description of the invention. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all conversions, equivalents, or substitutes included in the spirit and scope of the present invention. In describing the present invention, even if shown in different embodiments, the same identification numbers are used for the same components.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and when describing with reference to the drawings, the same or corresponding components are assigned the same reference numerals, and overlapping descriptions thereof will be omitted. .

In the following embodiments, terms such as first and second are used for the purpose of distinguishing one component from another component without limiting meaning.

In the following examples, expressions in the singular number include plural expressions unless the context clearly dictates otherwise.

In the following embodiments, terms such as include or have mean that features or components described in the specification exist, and do not preclude the possibility that one or more other features or components may be added.

In the drawings, the size of components may be exaggerated or reduced for convenience of description. For example, since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited to those shown.

When an embodiment is otherwise implementable, a specific process sequence may be performed differently from the described sequence. For example, two processes described in succession may be performed substantially simultaneously, or may be performed in an order reverse to the order described.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

The present invention provides a method for producing a powder suitable for a silicon active material for a secondary battery by crushing a silicon lump and classifying the pulverized product, and a silicon powder prepared by crushing and classifying the silicon lump.

In this specification, the silicon mass is metallurgical grade silicon, or UMG silicon (upgraded metallurgical grade silicon), or polycrystalline silicon, or polycrystalline silicon ingot, or polysilicon wafer (polycrystalline wafer) ), or single-crystal silicon ingot, or single-crystal silicon wafer, and the process of producing metal silicon, UMG silicon, polysilicon, polysilicon ingot, polysilicon wafer, single-crystal silicon ingot or single-crystal silicon wafer It may include by-products in the form of lumps, plates, or particulates generated from silicon agglomerates, which may have a size of several tens of nanometers to several meters. The silicon element content of the silicon mass is 90% by weight or more, preferably 98% by weight or more, and more preferably 99% by weight or more.

In the present specification, grinding includes all unit operations of further reducing the size of particles by applying energy to particles input as raw materials in a separate step of the present invention. In the present invention, grinding may include a unit operation of increasing a specific surface area per unit weight of silicon particles.

In this specification, classification includes all unit operations of dividing a plurality of particles having different particle sizes into particles larger than the target particle size and particles smaller than the target particle size.

In this specification, the silicon particle is a single crystal (single crystalline), or a polycrystalline (poly crystalline) in which crystallites are bonded to each other with grain boundaries interposed therebetween.

In the present specification, silicon powder is an individual particle or an aggregate of primary particles made of silicon single crystal or silicon polycrystal, or an agglomerate or an aggregate of secondary particles in which individual particles or primary particles are weakly attached to each other.

In the present specification, the average particle diameter (D50) is a particle size distribution curve that continuously displays the number of particles corresponding to each particle size or the number of particles included in the particle size range when all particles are placed in order according to the particle size ( particle size distribution curve), which corresponds to 50% of the volumetric accumulation amount, and this average particle diameter (D50) may be, for example, a value measured using a laser scattering method. . It should be understood that when the particle size, that is, the particle size, is indicated without special mention or designation, it means the 50% cumulative particle size D50 measured by the laser scattering method.

In this specification, um means a micrometer (μm, micrometer, 10 ^-6 m).

The present invention provides a method for producing silicon powder usable as an anode active material for a secondary battery and a silicon powder usable as an anode active material. A method for producing a silicon powder for use and a silicon powder are provided.

1 shows a method for manufacturing silicon powder for a secondary battery according to an embodiment of the present invention, FIG. 2 shows a particle size distribution of silicon powder according to an embodiment of the present invention, FIG. 3 shows a particle size distribution of a comparative example, and FIG. Life characteristics according to charge and discharge cycles of secondary batteries manufactured in Examples and Comparative Examples of the invention are shown, and FIG. 5 shows the effect of silicon powder of less than 1 μm included in the silicon powder on the performance of the secondary battery, and FIG. It shows the aggregation phenomenon of silicon powder.

Referring to FIG. 1, a method for manufacturing silicon powder for a secondary battery according to an embodiment of the present invention,

Obtaining a first powder by crushing the silicon lump to an average particle diameter (D50) of 100um to 1000um (S110);

Grinding the first powder to a size of 10 um to 200 um to obtain a second powder (S120);

Obtaining a third powder by pulverizing the second powder to a size of 1 um to 100 um (S130);

Obtaining a fourth powder by removing particles larger than 25um to 45um from the third powder (S140);

It may include a step (S150) of obtaining a fifth powder by removing particles smaller than 1 μm from the fourth powder.

In the present invention, the silicon lump is metal silicon, or UMG silicon, or polysilicon, or polysilicon ingot, or polysilicon wafer, or single crystal silicon ingot, or single crystal silicon wafer, or metal silicon, or UMG silicon, or polysilicon or poly It may contain by-products in the form of lumps, plates, or particles generated during the production of silicon ingots, polysilicon wafers, single-crystal silicon ingots or single-crystal silicon wafers.

The size of the silicon lump is suitable for 10mm to 100mm that can be introduced as a raw material in step S110. The size of the silicon lump is preferably 1 mm to 50 mm, and the size of the silicon lump is more preferably 1 mm to 30 mm. If the size of the silicon lump exceeds 100 mm, it may be necessary to break the silicon lump into an appropriate size that can be introduced as a raw material for step S110. In this case, a jaw crusher, a gyrotory crusher, a single roll crusher, a double roll crusher, and the like can be used.

When a silicon lump of an appropriate size is prepared, it is crushed to a size of 100um to 1000um using various crushers to obtain a first powder (S110). Roller mills, disc mills, hammer mills, disc pin mills, impact mills and ball mills can be used for this purpose. Here, the size of the first powder may be an average particle diameter (D50).

If the size of the first powder is less than 100um, it takes too much time to crush the silicon lump, and if the size of the first powder exceeds 1000um, it may take a lot of time to crush the powder in steps S120 and S130. there is.

In one embodiment, before or after step S110, particle classification may be additionally performed using a vibrator, an air classifier, a decanter, a liquid cyclone, or the like. For example, the silicon lump may be crushed through step S110, and particle classification may be performed thereon to finally obtain a first powder having an average particle diameter of 100 um to 1000 um.

The first powder is pulverized to a size of 10 um to 200 um to obtain a second powder (S120). Suitable mills for step S120 include roller mills, ball mills, centrifugal mills, vibration mills, satellite mills, high-speed rotary impact mills, and high-speed shear mills. Here, the size of the second powder may be an average particle diameter (D50).

If the size of the second powder is less than 100um, it takes too much time to grind the first powder, and if the size of the second powder exceeds 200um, it may take a lot of time to grind the powder in step S130. .

In one embodiment, before or after step S120, particle classification may be additionally performed using a vibrator, an air classifier, a settling tank, a liquid cyclone, or the like. For example, the first powder may be pulverized through step S120 and subjected to particle classification to finally obtain a second powder having an average particle diameter of 10 um to 200 um. The second powder is pulverized to a size of 1 um to 100 um. to perform step S130 to obtain a third powder. Suitable pulverizers for step S130 include vibrating ball mills, satellite mills, jet mills, high-speed rotary impact mills, high-speed shear type pulverizers, high-frequency vibration mills, and attrition mills. Here, the size of the third powder may be an average particle diameter (D50).

In one embodiment, particle classification may be additionally performed before step S130 or after step S120 using a vibrator, a settling tank, a liquid cyclone, or the like. For example, the second powder may be pulverized through step S130 and subjected to particle classification to finally obtain a third powder having an average particle diameter of 1 um to 100 um.

In one embodiment, crushing or crushing devices used in steps S110, S120, and S130 may use different devices or set different control conditions of the same device. For example, in step S110, a grinding device using balls having relatively large particles may be used, and balls having gradually smaller particles may be used in subsequent steps. Alternatively, the rotational speed of the grinder may be lowered from step S110 to step S130.

Step S140 is performed to obtain a fourth powder by removing particles larger than 25um to 45um from the third powder. Devices suitable for step S140 include a vibrator, an air classifier, a sedimentation tank, a liquid cyclone, and the like. Step S140 may be performed before the subsequent step S150. Alternatively, step S140 may be performed after step S150. However, in order to easily remove relatively small particles in step S150, step S140 is preferably performed before step S150.

A step S150 of obtaining a fifth powder by removing particles smaller than 1 μm from the fourth powder is performed. Equipment suitable for step S150 includes an air classifier, a turbo classifier, a sedimentation tank, a liquid cyclone, and the like.

In one embodiment, particles smaller than 1 μm generated in step S150 may be separately collected and used as a raw material for manufacturing a nanometer-sized silicon active material for a secondary battery or a nanometer-sized silicon active material for a secondary battery.

In one embodiment, the average particle diameter (D50) of the fifth powder obtained through steps S110 to S150 is 0.1 um to 45 um. The average particle diameter (D50) of the fifth powder is preferably 0.5um to 25um. More preferably, the average particle diameter (D50) of the fifth powder is more preferably 1 um to 10 um. When the average particle diameter (D50) of the fifth powder is less than 1 μm, the silicon powder is excessively miniaturized, and the silicon powder is not dispersed and aggregated with each other, and performance characteristics of the secondary battery may be deteriorated. In addition, when the average particle diameter (D50) of the fifth powder exceeds 10 um, the particles of the silicon powder may become too large and D100 (Dmax) may exceed 25 um to 45 um.

The fifth powder obtained through steps S110 to S150 may be a raw material for preparing silicon powder for a secondary battery having a particle size of nanometers.

In order to remove metal impurities other than silicon before and after the individual steps of crushing, pulverizing, and finely pulverizing the silicon lump, a magnetic separator including a de-iron device [Korean Registered Patent 10-1498693] disclosed by the applicant of the present invention as a patent can be used. can

Air classifiers, fluidized bed classifiers, liquid cyclones, etc. may be used to remove non-metallic impurities other than silicon before and after individual steps of crushing, pulverizing, and finely pulverizing silicon lumps.

In order to manufacture silicon powder for secondary batteries, steps S110 to S150, including a silicon crushing preparation step that can be performed before step S110, are carried out as a dry process that does not use liquids such as water or alcohol, or using liquids such as water or alcohol. It can be carried out as a wet process. In the case of performing steps S110 to S150 as a wet process, filtration and/or drying and/or disaggregation unit processes may be included for the silicon powder resulting from the individual steps.

(Example 1)

Using the polysilicon by-product as a raw material, powder having an average particle diameter (D50) of 10 um to 200 um was prepared through a jaw crusher and a hammer mill, and powder having an average particle diameter (D50) of 1 um to 100 um was obtained using an air jet mill. This powder is put into a settling tank and mixed, and after stirring the mixed solution with a stirrer, it is left still. After a certain period of time, the semen was removed to collect a part of the lower precipitate slurry, and particles larger than 25 μm to 45 μm were removed, and particles smaller than 1 μm were also removed. The particle size distribution was measured by laser scattering method. The results are shown in FIG. 2 . 2, the horizontal axis is the particle size (um), and the vertical axis is the fraction (%) of the particles corresponding to the particle size on the horizontal axis.

(Example 2)

Using the polysilicon by-product as a raw material, powder having an average particle diameter (D50) of 10 um to 200 um was prepared through an impact mill, and powder having an average particle diameter (D50) of 1 um to 100 um was obtained using a planetary mill. Particles larger than 25 μm to 45 μm were removed from this powder using an air flow classifier to perform the same function as the dipping method in Example 1, and particles smaller than 1 μm were also removed. Part of the classified powder was collected and the particle size distribution was measured by laser scattering method. The results are shown in FIG. 2 .

(Example 3)

Using the polysilicon by-product as a raw material, powder having a 50% cumulative particle size D50 of 10 um to 200 um was prepared using a roller mill, and powder having a 1 um to 100 um was obtained using a jet mill. This powder is put into a settling tank and mixed, and after stirring the mixed solution with a stirrer, it is left still. After a certain period of time, the semen was removed to collect a part of the lower precipitate slurry, and particles larger than 25 μm to 45 μm were removed, and particles smaller than 1 μm were also removed. The particle size distribution was measured by laser scattering method. The results are shown in FIG. 2 .

(Comparative Example 1)

Using the polysilicon by-product as a raw material, powder having an average particle diameter (D50) of 10 um to 200 um was prepared through a jaw crusher and a hammer mill, and powder having an average particle diameter (D50) of 1 um to 100 um was obtained using an air jet mill. Part of the obtained powder was collected without performing a separate classification process, and the particle size distribution was measured by a laser scattering method. The result is shown in FIG. 3.

(Comparative Example 2)

Using polysilicon as a raw material, powder having an average particle diameter (D50) of 10 um to 200 um was prepared through an impact mill, and powder having an average particle diameter (D50) of 1 um to 100 um was obtained using a planetary mill. Part of the obtained powder was collected without performing a separate classification process, and the particle size distribution was measured by a laser scattering method. The result is shown in FIG. 3.

(Comparative Example 3)

Using the polysilicon by-product as a raw material, powder having an average particle diameter (D50) of 10 um to 200 um was prepared using a roller mill, and powder having an average particle diameter (D50) of 1 um to 100 um was obtained using a jet mill. Part of the obtained powder was collected without performing a separate classification process, and the particle size distribution was measured by a laser scattering method. The result is shown in FIG. 3.

Table 1 shows the particle size distribution of the silicon powder obtained in Examples and Comparative Examples. In Table 1, D10, D50, and D90 are cumulative particle sizes of 10%, 50%, and 90%, and SPAN is defined as follows. As defined below, the larger the SPAN value, the wider the particle size distribution of the silicon powder, and the smaller the SPAN value, the narrower the particle size distribution, indicating that the particle size of the silicon powder is generally close to D50.

D10 [um] D50 [um] D90 [um] SPAN ≤2um[%] ≤1um[%] Example 1 3.07 4.54 6.49 0.76 0.63 0 Example 2 3.16 4.66 6.62 0.74 0.50 0 Example 3 3.19 4.72 6.75 0.75 0.47 0 Comparative Example 1 3.31 6.25 10.50 1.15 2.87 0.89 Comparative Example 2 3.27 6.34 11.05 1.23 2.66 0.51 Comparative Example 3 3.39 6.44 10.90 1.17 2.80 0.89

There is a difference between Examples and Comparative Examples in whether particles larger than 25 μm to 45 μm are removed through dry or wet classification of powders that have undergone crushing, pulverization, and pulverization, and particles smaller than 1 μm are removed. Accordingly, it can be seen that the SPANs of Examples 1 to 3 are all less than 1, whereas the SPANs of Comparative Examples 1 to 3 exceed 1. In particular, the SPAN of Examples 1 to 3 is 0.8 or less, and it can be seen that the particle size deviation between the finally obtained silicon powders is small. A secondary battery was manufactured using the silicon powder obtained in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3, and its performance was evaluated. The first cycle charge and discharge results are shown in Table 2. In addition, the results of performing charge and discharge 200 times are shown in FIG. 4 .

Medium particle size of silicone
um charging capacity
mAh/g discharge capacity
mAh/g efficiency
discharge/charge, % Example 1 4.54 3928 3563 90.7 Example 2 4.66 3926 3620 92.2 Example 3 4.72 3880 3593 92.6 Comparative Example 1 6.25 3967 3650 92.0 Comparative Example 2 6.34 3916 3611 92.2 Comparative Example 3 6.44 3940 3601 91.4

Referring to Table 2 and FIG. 4, it can be seen that the first cycle characteristics are similar to the examples and the comparative example, but the life characteristics of the comparative example having a large SPAN value are inferior.

This is because when the silicon powder contains fine particles of less than 1 μm, the silicon powder is not sufficiently dispersed and aggregation occurs, which deteriorates the characteristics of the secondary battery (see FIG. 6). On the other hand, as in the embodiment of the present invention, when particles of less than 1 μm are removed from the finally obtained silicon powder, the aggregation of the silicon powder is fundamentally blocked, thereby significantly improving the performance characteristics of the manufactured secondary battery. .

In particular, in the method for manufacturing silicon powder according to an embodiment of the present invention, reliability and durability of an electrode current collector and electrode manufacturing equipment can be secured by removing silicon powder particles larger than the electrode thickness. More specifically, the coating thickness of the negative electrode active material in the current collector is usually 30um to 50um. The method for manufacturing silicon powder according to an embodiment of the present invention removes silicon powder particles larger than the size of the electrode thickness, thereby preventing the silicon powder particles from entering the electrode current collector and damaging the copper thin film, and manufacturing an electrode. Damage to equipment can be prevented.

As an additional experiment, in order to confirm how the more particles of 1 μm or less in the silicon powder affect the characteristics of the secondary battery, as shown in Table 3, silicon powder containing about 25% of 1 μm or less (median particle size 1.611 μm, Experimental Example 1) and Characteristics were evaluated using silicon powder containing about 14% of 1 um or less (median particle size 3.055 um, Experimental Example 2). As a result, as shown in Table 4 and FIG. 5, it can be seen that the charge capacity, discharge capacity, and charge/discharge efficiency deteriorate as the number of particles of 1 μm or less in the silicon powder increases.

D10 [um] D50 [um] D90 [um] SPAN ≤2um[%] ≤1um[%] Experimental Example 1 0.603 1.611 3.423 1.751 63.04 25.51 Experimental Example 2 0.731 3.055 7.194 2.116 30.22 13.65

Medium particle size of silicone
um charging capacity
mAh/g discharge capacity
mAh/g efficiency
discharge/charge, % Experimental Example 1 1.611 3865 3336 86.3 Experimental Example 2 3.055 3815 3487 91.4

Through this experiment, it can be seen that fine particles of 1 μm or less in the silicon powder adversely affect the performance characteristics of the secondary battery.

Specific technical details described in the embodiments are only examples, and do not limit the technical scope of the embodiments. In order to briefly and clearly describe the description of the invention, descriptions of conventional general techniques and configurations may be omitted. In addition, the connection of lines or connection members between the components shown in the drawing is an example of functional connection and / or physical or circuit connection, which can be replaced in an actual device or additional various functional connections, physical connections, or circuit connections. In addition, if there is no specific reference such as "essential" or "important", it may not necessarily be a component necessary for the application of the present invention.

“Above” or similar designations described in the description and claims of the invention may refer to both singular and plural, unless otherwise specifically limited. In addition, when a range is described in an embodiment, it includes an invention in which individual values belonging to the range are applied (unless there is no description to the contrary), and each individual value constituting the range is described in the description of the invention. same. In addition, if there is no clear description or description of the order of steps constituting the method according to the embodiment, the steps may be performed in an appropriate order. Embodiments are not necessarily limited according to the order of description of the steps. The use of all examples or exemplary terms (eg, etc.) in the embodiments is simply to describe the embodiments in detail, and unless limited by the claims, the examples or exemplary terms limit the scope of the embodiments. It is not. In addition, those skilled in the art will appreciate that various modifications, combinations and changes may be made according to design conditions and factors within the scope of the appended claims or equivalents thereof.

Claims (8)

Obtaining a first powder by crushing the silicon lump to an average particle diameter (D50) of 100um to 1000um;
obtaining a second powder by pulverizing the first powder to an average particle diameter of 10 um to 200 um;
Obtaining a third powder by pulverizing the second powder to an average particle diameter of 1 um to 100 um;
Obtaining a fourth powder by removing particles larger than 45um from the third powder; and
obtaining a fifth powder by classifying the fourth powder to remove particles smaller than 1 μm from the fourth powder;
The average particle diameter of the fifth powder is 1 um to 10 um,
The fifth powder does not contain particles smaller than 1um, and the SPAN is less than 1, a method for producing a silicon powder for a secondary battery.
Here, SPAN is defined by the following formula (D10 is the cumulative 10% particle size of the fifth powder, D50 is the cumulative 50% particle size of the fifth powder, and D90 is the cumulative 90% particle size of the fifth powder).

delete delete According to claim 1,
The silicon mass is metallurgical grade silicon, or upgraded metallurgical grade silicon, or polycrystalline silicon, or polycrystalline silicon ingot, or polysilicon wafer (polycrystalline wafer), Or a single crystal silicon ingot, or a single crystal silicon wafer, which is generated in the process of producing metal silicon, UMG silicon, polysilicon, polysilicon ingot, polysilicon wafer, single crystal silicon ingot or single crystal silicon wafer. A method for producing a silicon powder for a secondary battery, comprising a by-product in the form of a bulk or plate or particulate form. According to claim 1,
At least one of the step of obtaining the first powder, the step of obtaining the second powder, and the step of obtaining the third powder further comprises the step of crushing or pulverizing and then classifying, respectively, a method for producing a silicon powder for a secondary battery . delete delete Claims 1, 4, and 5, wherein the silicon powder produced by the method for producing a silicon powder for a secondary battery according to any one of claims.

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