KR20200094265A - Method for manufacturing silicon nanoparticle and method for manufacturing carbon coating silicon nanoparticle of a secondary cell - Google Patents

Abstract

The present invention relates to a method of manufacturing silicon nanoparticles and a method of manufacturing carbon-coated silicon nanoparticles for a secondary battery, which: can save time in manufacturing etched silicon nanoparticles through a simple process of etching after preparing milled silicon nanoparticles by ball milling of silicon microparticles; can manufacture etched silicon nanoparticles having excellent electrical properties with a high recovery rate at low cost without expensive equipment or harsh process conditions such as high pressure and high temperature; and can maximize charging efficiency of a secondary battery using the same.

Description

Manufacturing method of silicon nanoparticles and manufacturing method of carbon nanoparticles for secondary battery {METHOD FOR MANUFACTURING SILICON NANOPARTICLE AND METHOD FOR MANUFACTURING CARBON COATING SILICON NANOPARTICLE OF A SECONDARY CELL}

The present invention relates to a method of manufacturing silicon nanoparticles and a method of manufacturing carbon coated silicon nanoparticles for a secondary battery, and more specifically, to prepare milling silicon nanoparticles by ball milling of silicon microparticles, and then etching silicon nanoparticles by a simple process of etching. It can save time in manufacturing, and can manufacture etched silicon nanoparticles with excellent electrical properties at low cost with high recovery rate without expensive equipment or harsh process conditions such as high pressure and high temperature, and using this, 2 The present invention relates to a method of manufacturing silicon nanoparticles that can maximize the charging efficiency of a secondary battery and a method of manufacturing carbon coated silicon nanoparticles for a secondary battery.

In general, silicon is abundant on the earth, but it is most frequently used as a non-toxic semiconductor material.

In recent years, as the demand for miniaturization, light weight, and flexibility of electronic devices has increased, silicon nanoparticles are of great interest to many researchers as a key element of application as a next-generation silicon-based opto-electronic device and nano device development. It is targeted.

Silicon nanoparticles are widely used in display field effect transistors (TFTs), solar cells using PN junctions, diodes, and biomarkers.

It is already known that silicon nanoparticles can be applied as a solution process based on field effect transistors (Appl. Phys. Lett., 2009, 94, 193509.) and hybrid solar cells (Nanoletters, 2009, 9, 449.). The solution process-based silicon nanoparticle thin film is very useful for the softening of electronic devices.

As an example, silicon (Si) is selected as an optimal material capable of realizing a high-capacity secondary battery, that is, a lithium-ion battery by having a theoretical capacity of 4200mAh/g, but when charging is performed in a lithium-ion battery, Li4. By reacting 4 and Si to form Li4.4Si, very high volume expansion up to about 400% occurs.

However, silicon (Si) has a property in which stress due to volume expansion is reduced when the particle size changes from micro size (µm) to nano size (nm), and by using these properties, nano size (nm), that is, silicon nanoparticles By manufacturing a silicon electrode, a high capacity secondary battery (lithium ion battery) can be easily implemented.

Meanwhile, various methods for manufacturing silicon nanoparticles are known.

The most common method is a method of chemically reducing a silicon source such as silicon tetrachloride or silicon triethyl orthosilicate, but these methods include excessive capping of silicon nanoparticles, oxidation of silicon nanoparticles, and impurities such as carbon after the sintering process. Due to this, it has the disadvantage that it may cause electrical characteristics of electronic devices containing silicon nanoparticles to deteriorate.

Another method is a method of depositing a silicon source by vapor-liquid-solid (VLS) or solid-liquid-solid (SLS), which is a severe reaction condition because the silicon source is deposited at high pressure and high temperature. In addition, it is difficult to handle and requires expensive equipment, and the yield of silicon nanoparticles is low.

Accordingly, there is an increasing demand for a method of manufacturing silicon nanoparticles that can be applied to a solution process base and solve conventional problems.

On the other hand, a method of manufacturing a silicon nanomaterial according to the prior art document (Republic of Korea Patent Publication No. 2015-0072976) powders a colloid containing a silica-containing material to obtain a powder containing a silica-containing material, and silica- Alkaline earth metal is added to the powder containing the contained material to form a mixture, and the heat treatment of the mixture is introduced to reduce the silica contained in the silica-containing material to silicon, and the colloid containing the silica-containing material is powdered. Nanoparticles of silicon particles should be nanostructured by performing re-stacking by adding a cation of an alkaline earth metal to a colloid containing a silica-containing material or freeze-drying a colloid containing a silica-containing material. Not only is it very difficult to reconcile, but it also takes a long time.

Republic of Korea Patent Publication No. 2015-0072976-Method for manufacturing silicon nanomaterial, and silicon nanomaterial prepared thereby

The objective of the present invention is to provide a silicon nanoparticle manufacturing method and a carbon coating silicon nanoparticle manufacturing method for a secondary battery, which are capable of guaranteeing productivity as well as ensuring excellent electrical properties, especially at the same time as ensuring rapid production of silicon nanoparticles. In the offer.

The present invention is to provide a method of manufacturing silicon nanoparticles and a carbon coating silicon nanoparticle for secondary batteries, which can be used as a negative electrode active material of a secondary battery having excellent electrical properties.

The present invention can save time in manufacturing the etched silicon nanoparticles by a simple process of etching after the milling silicon nanoparticles are prepared by ball milling of the silicon microparticles, and a severe process such as expensive equipment or high pressure and high temperature It is possible to manufacture etched silicon nanoparticles with excellent electrical properties at low cost without conditions, and by using this method for manufacturing carbon coating silicon nanoparticles for secondary batteries to maximize charging efficiency. And it is to provide a method for producing a carbon coating silicon nanoparticles for secondary batteries.

The present invention is to provide a method for producing silicon nanoparticles that can economically produce silicon nanoparticles and exhibit excellent electrical properties due to their small size and uniformity, and a method for producing carbon coated silicon nanoparticles for secondary batteries.

Method for producing silicon nanoparticles according to the present invention for achieving the above object,

Ball milling silicon microparticles having a particle size of µm to prepare milling silicon nanoparticles having a particle size of nm;

A basic feature of the technical method is to include the step of preparing the etched silicon nanoparticles having a particle size of nm by etching the milling silicon nanoparticles.

Method for producing carbon coated silicon nanoparticles for secondary batteries according to the present invention for achieving the above object,

Ball milling silicon microparticles having a particle size of µm to prepare milling silicon nanoparticles having a particle size of nm;

Etching the milling silicon nanoparticles to prepare a etched silicon nanoparticles of ㎚ particle size,

Step of preparing a silicon nanoparticle dispersion by ball milling while adding distilled water to the etching silicon nanoparticles,

A step of preparing a colloidal solution by mixing the silicon nanoparticle dispersion, glucose, distilled water and a carbon precursor;

Step of preparing a silicon carbon precursor aggregate by applying heat in an argon gas atmosphere while spraying the colloidal solution as a droplet,

It comprises the steps of heat-treating the silicon carbon precursor aggregate in an argon gas atmosphere to prepare the silicon nanoparticles coated with the carbon precursor is characterized by the following in the technical method.

The present invention has the effect of ensuring productivity as well as ensuring rapid electrical production of small and uniform etched silicon nanoparticles, and at the same time, excellent electrical properties due to its small size and uniformity.

The present invention has an effect that can be utilized as a negative electrode active material of a secondary battery having excellent electrical properties.

The present invention can save time in manufacturing the etched silicon nanoparticles by a simple process of etching after the milling silicon nanoparticles are prepared by ball milling of the silicon microparticles, and a severe process such as expensive equipment or high pressure and high temperature Etching silicon nanoparticles having excellent electrical properties with high recovery rate without conditions can be manufactured at a low cost, and by using this, it is possible to maximize charging efficiency by applying to the method of manufacturing carbon coated silicon nanoparticles for secondary batteries.

The present invention can economically produce silicon nanoparticles, and has the effect of exerting excellent electrical properties due to its small size and uniformity.

1A is a flow chart showing a method of manufacturing silicon nanoparticles according to the present invention.
Figure 1b is a flow chart showing a method of manufacturing a carbon coating silicon nanoparticles for a secondary battery according to the present invention.
Figure 2 is a graph showing the particle size analysis of the etched silicon nanoparticles prepared by the method of manufacturing silicon nanoparticles according to the present invention.
Figure 3 is a SEM photograph showing the etching silicon nanoparticles prepared by the method of manufacturing silicon nanoparticles according to the present invention.
4 is an XPS spectrum showing the etching silicon nanoparticles produced by the method of manufacturing silicon nanoparticles according to the present invention.
Figure 5 is an XRD spectrum showing the etching silicon nanoparticles prepared by the silicon nanoparticle manufacturing method according to the present invention.
6 and 7 are SEM and TEM photographs respectively showing carbon coated silicon nanoparticles produced by the method for manufacturing carbon coated silicon nanoparticles for secondary batteries according to the present invention.
8 is a graph showing the results of charging and discharging experiments after preparing a secondary battery by applying the carmon-coated silicon nanoparticles prepared by the method of manufacturing carbon coated silicon nanoparticles for a secondary battery according to the present invention.

A preferred embodiment of the method for manufacturing a silicon nanoparticle according to the present invention and a method for manufacturing a carbon coated silicon nanoparticle for a secondary battery will be described with reference to the drawings, and a number of examples may exist, and through such an embodiment The objects, features and advantages of the present invention will be better understood.

1A is a flow chart showing a method of manufacturing silicon nanoparticles according to the present invention.

The method of manufacturing silicon nanoparticles according to the present invention provides milling silicon nanoparticles having a particle size of nm by ball milling silicon microparticles having a particle size of µm as shown in FIG. 1A (S10), and etching the milling silicon nanoparticles to form a nanometer particle size. It consists of a step (S20) of preparing the etched silicon nanoparticles.

The milling silicon nanoparticles having a particle size of nm are rapidly prepared by ball milling silicon microparticles having a particle size of µm, that is, milling silicon nanoparticles having a particle size of 300 to 800 nm, preferably 500 nm. Efficient preparation of etched silicon nanoparticles with a particle size of 80 nm, preferably 80 nm, enables rapid production of small and uniform etched silicon nanoparticles, guarantees productivity, and is particularly small and uniform, providing excellent electrical The characteristics can be guaranteed.

Specifically, the S10 step uses silicon zirconia balls with a zirconia ball of 500 to 700 rpm (if 500 rpm or less, the time is long, and if it is 700 rpm or more, the stress on silicon microparticles with a particle size is too high, resulting in poor electrical properties) 2 ~ It is milled for 4 hours [it is difficult to manufacture uniform milling silicon nanoparticles with a particle size of less than 2 hours and is not efficient in time when it is more than 4 hours] and milling for 300 to 800 nm [when etching is less than 300 nm] If it takes longer and is more than 800nm, the electrical properties are deteriorated due to the high stress during ball milling of the milling silicon nanoparticles] It is possible to prepare the milling silicon nanoparticles having a particle size.

In this case, the step S20 is 30 to 80 by centrifugation after the milling silicon nanoparticles of step S10 are stirred and dispersed in distilled water and etched by adding a reagent of any one of Na ₂ O, KOH and NaOH reagents or a mixture thereof. It is possible to provide etched silicon nanoparticles with a particle size of ㎚.

When any one of Na ₂ O, KOH, and NaOH reagents or a mixture thereof is introduced into milling silicon nanoparticles having a particle size of 300 to 800 nm together with midstream water to be easily etched and centrifuged to etch silicon of 30 to 80 nm particle size It is possible to rapidly prepare nanoparticles.

At this time, the milling silicon nanoparticles and reagents have a weight of 1:1 to 20 [if the ratio is 1:1 or less, the weight ratio of the reagent cannot be effectively realized, and if it is 1:20 or more, efficiency cannot be maximized compared to the weight ratio of the reagent] It is possible to achieve the etching of the milling silicon nanoparticles more quickly and efficiently by making the ratio.

Then, the step S20 is to etch the silicon nanoparticles prepared by centrifugation after etching in water and ultrasonic cleaning to completely remove impurities.

1B is a flow chart showing a method of manufacturing carbon coated silicon nanoparticles for a secondary battery according to the present invention.

The method for manufacturing carbon coated silicon nanoparticles for a secondary battery according to the present invention is ball milling silicon microparticles having a particle size of µm as shown in FIG. 1B to prepare milling silicon nanoparticles having a particle size of ㎚ (S100), milling silicon nanoparticles Etching to prepare etched silicon nanoparticles of nm particle size (S200), ball milling while adding distilled water to the etched silicon nanoparticles to prepare a silicon nanoparticle dispersion (S300), silicon nanoparticle dispersion, glucose, distilled water and carbon Prepare a colloidal solution by mixing the precursor (S400), apply heat in an argon gas atmosphere while spraying the colloidal solution as a droplet (S500), and then heat-treat the silicon carbon precursor aggregate in an argon gas atmosphere to carbon It consists of a step (S600) of preparing a precursor coated carbon coating silicon nanoparticles.

The milling silicon nanoparticles having a particle size of nm are rapidly prepared by ball milling silicon microparticles having a particle size of µm, that is, milling silicon nanoparticles having a particle size of 300 to 800 nm, preferably 500 nm. Etching silicon nanoparticles with an 80 nm particle size, preferably 80 nm particle size, can be precisely provided, thereby ensuring rapid productivity of small and uniform etched silicon nanoparticles, ensuring productivity while ensuring electrical properties, and then again While adding distilled water to the etched silicon nanoparticles, ball milling is performed to prepare a silicon nanoparticle dispersion liquid, and this silicon nanoparticle dispersion liquid, glucose, distilled water and carbon precursors are mixed to form a colloidal solution [silicon nanoparticle dispersion liquid along with a carbon precursor. To spread evenly], spraying colloidal solution as droplets, applying heat in an argon gas atmosphere to prepare a silicon carbon precursor aggregate, and then heat-treating the silicon carbon precursor aggregate in an argon gas atmosphere to coat carbon coated silicon coated with carbon precursors. The nanoparticles are prepared to be used as a negative electrode active material of a secondary battery having excellent electrical properties.

At this time, in the step S500, the temperature of the argon gas atmosphere is 180 to 200°C so that the silicon carbon precursor aggregate can be easily provided, and in the step S600, the temperature of the argon gas atmosphere is 280 to 320°C to the silicon nanoparticles. It ensures that the carbon precursor can be coated firmly and uniformly.

In addition, milling silicon nanoparticles having a particle size of nm are rapidly prepared by ball milling silicon microparticles having a particle size of µm, that is, milling silicon nanoparticles having a particle size of 300 to 800 nm, preferably 500 nm, and then etching the particle size, i.e. Etching silicon nanoparticles with a particle size of 30 to 80 nm, preferably 80 nm, can be precisely provided, thereby ensuring productivity with rapid production of small and uniform etched silicon nanoparticles, while at the same time being particularly small and uniform in size. It is possible to ensure excellent electrical properties.

Furthermore, the step S100 is 2 to 4 with the use of zirconia balls of silicon microparticles in the range of 500 to 700 rpm (in case of 500 rpm or less, the time is long and when 700 rpm or more, the stress on silicon microparticles with the particle size is too high, resulting in poor electrical properties). Milling for 300 [800 nm or less [300 nm or less] by milling for a period of time [it is difficult to produce uniform milling silicon nanoparticles with a particle size of less than 2 hours and is not efficient in time when more than 4 hours] If it takes more than 800nm, milling silicon nanoparticles are subjected to a lot of stress during ball milling, resulting in reduced electrical properties.] It is possible to prepare milling silicon nanoparticles having a particle size.

At this time, the step S200 is 30 to 80 by centrifuging after adding the reagent of any one of Na ₂ O, KOH, and NaOH reagents or a mixture thereof while etching and dispersing the milling silicon nanoparticles of step S100 in distilled water with stirring and dispersing. It is possible to provide etched silicon nanoparticles with a particle size of ㎚.

When any one of Na ₂ O, KOH, and NaOH reagents or a mixture thereof is introduced into milling silicon nanoparticles having a particle size of 300 to 800 nm together with midstream water to be easily etched and centrifuged to etch silicon of 30 to 80 nm particle size It is possible to rapidly prepare nanoparticles.

Furthermore, the milling silicon nanoparticles and reagents are 1:1 to 20 [1:1 or less, the weight ratio of the reagents is low, so it is not possible to efficiently perform etching, and when it is 1:20 or more, the efficiency compared to the weight ratio of the reagents cannot be maximized. It is made to be made by the weight ratio of], so that the etching of the milling silicon nanoparticles can be realized more quickly and efficiently.

In addition, the step S200 is performed by ultrasonic cleaning by mixing the etched silicon nanoparticles prepared by centrifugation after etching in water to completely remove impurities.

As described above, the present invention can save time in manufacturing etched silicon nanoparticles by a simple process of etching after preparing milling silicon nanoparticles by ball milling of silicon microparticles, such as expensive equipment, high pressure, and high temperature. It is possible to manufacture etched silicon nanoparticles having excellent electrical properties at low cost with high recovery rate without harsh process conditions, and to maximize charging efficiency by applying to the method of manufacturing carbon coated silicon nanoparticles for secondary batteries.

[Example 1] Preparation of silicon nanoparticles

a) Milling of 15 micrometers of silicon microparticles with 15 zirconia balls was performed, and milling was performed at 600 RPM for 3 hours to prepare 14 g of milling silicon nanoparticles having a particle size of 500 nm.

b) 3 g of milling silicon nanoparticles having a particle size of 500 nm obtained in step a) were stirred and dispersed in distilled water, and 10 ml of 5 wt% Na ₂ O solution was slowly added to perform etching for 10 hours, and centrifuged at 10,000 rpm for 30 minutes. After removing the test solution, the obtained 80 nm particle size of the etched silicon nanoparticles was mixed in water at 1:2, stirred and ultrasonically washed three times to prepare a final etched silicon nanoparticle.

c) 3 g of the etched silicon nanoparticle powder prepared in step b) was added to 57 g of distilled water and subjected to a ball mill treatment for 30 minutes to prepare a 5 wt% silicon nanoparticle dispersion.

2 is a graph showing the particle size analysis of the etched silicon nanoparticles prepared by the method of manufacturing silicon nanoparticles according to the present invention, showing a normal distribution as a result of the particle size analysis, and it was found that the central particle size was 89.1 nm.

3 is a SEM photograph showing an etched silicon nanoparticle prepared by the method of manufacturing a silicon nanoparticle according to the present invention, it was found that the etched silicon nanoparticles have a uniform particle size and a smooth surface.

4 is an XPS spectrum showing the etched silicon nanoparticles prepared by the method of manufacturing silicon nanoparticles according to the present invention, it is confirmed that the Si-O binding peak appears near 103eV when XPS analysis is performed immediately without surface treatment of the etched silicon nanoparticles. This is due to surface oxidation generated during the preparation and mounting of the analytical sample. After ball milling through sputtering in the XPS chamber, only peaks due to Si metal bonding remain.

As a result, it was confirmed that etched silicon nanoparticles were effectively produced in the silicon nanoparticle manufacturing process.

FIG. 5 is an XRD spectrum showing the etched silicon nanoparticles prepared by the method of manufacturing silicon nanoparticles according to the present invention. It can be seen that diffraction peaks appearing in silicon oxide are not observed and only have all the characteristic peaks of the silicon single crystal. there was.

[Example 2] Carbon coated silicon nanoparticles for secondary batteries

A colloidal solution in which silicon nanoparticles dispersed in 3 g of silicon nanoparticles and 2 g of glucose was dispersed in distilled water and carbon precursor was prepared. The colloidal solution was sprayed as droplets using a commercial spray dryer (Mini Spray Drier, B-191, Buchi) that generates droplets using a double nozzle.

The sprayed droplets were transported to a heating furnace of 190°C by argon gas having a flow rate of 4.5 L/min, and distilled water was evaporated at a set temperature to prepare a silicon carbon precursor aggregate.

The thus prepared silicon carbon precursor aggregate was heat-treated at 300° C. for 4 hours under an argon gas atmosphere to prepare carbon coated silicon nanoparticles coated with carbon precursors, and the average particle size of these carbon coated silicon nanoparticles was 5 μm.

6 and 7 are SEM pictures and TEM pictures respectively showing carbon coated silicon nanoparticles prepared by the method of manufacturing carbon coated silicon nanoparticles for a secondary battery according to the present invention, and it was confirmed that aggregation was good in a round circle. , It was confirmed that the surface of the carbon is uniformly coated as about 20 nm.

Carbon-coated silicon nanoparticles prepared by the present invention, ketjenblack, and PVDF (Polyvinylidene fluoride) were mixed in a weight ratio of 40:40:20, and a negative electrode material was prepared through doctor blading.

Thereafter, the prepared negative electrode material, lithium metal, electrolyte and separator were mixed to prepare a lithium ion battery as follows.

Samples synthesized by the method of Example, copper black by mixing carbon black (Acetylene black) as a conductor and polyvinylidene difluoride (PVDF) as a binder in a weight ratio of 20:20:50:10 (0.4g:0.4g:1g:0.2g) After pressing the whole, it was dried in a vacuum oven at 120°C for 1 hour. A half cell was prepared using lithium metal foil as the counter electrode and the reference electrode. As a separator, celgard 2400 was used.

In addition, a 2-electrode half cell of coin form (CR2032) was prepared using 0.5 cc of 1 mol concentration LiPF6 / ethylene carbonate (EC):dimethyl carbonate (DMC) (volume ratio 1:1) as the electrolyte and charged and discharged at a constant current at room temperature. The experiment was conducted.

Comparative Example 1 Instead of the carbon coated silicon nanoparticles prepared in Example 1, bulk silicon (1 µm) was used to prepare a coin-shaped two-electrode half cell in the same manner as in Example 2, and a charge/discharge experiment with constant current at room temperature. Was performed.

Figure 8 shows a stable appearance compared to the comparative example up to 50 cycles by looking at the graph of the results of charging and discharging experiments after preparing the secondary battery by applying the carmon-coated silicon nanoparticles prepared by the method of manufacturing carbon-coated silicon nanoparticles for a secondary battery according to the present invention I could observe.

The present invention can be used in the industry of manufacturing silicon nanoparticles and in the industry related to secondary batteries.

Comparative Example 1 of Figure 8: Conventional charge and discharge graph
Example 2 of Figure 8: Charging and discharging graph of the present invention

Claims (13)

A step (S10) of ball milling silicon microparticles having a particle size of µm to prepare milling silicon nanoparticles having a particle size of ㎚,
And etching the milling silicon nanoparticles to prepare etched silicon nanoparticles having a particle size of S (S20). According to claim 1,
In the step S10, the milling silicon nanoparticles have a particle size of 300 to 800 nm,
The method of manufacturing silicon nanoparticles, characterized in that the etching silicon nanoparticles in the step S20 is 30 to 80 nm particle size. According to claim 2,
In the step S10, the silicon microparticles are milled at 500 to 700 rpm for 2 to 4 hours using a zirconia ball to prepare the milling silicon nanoparticles having a particle size of 300 to 800 nm. According to claim 3,
In step S20, the milling silicon nanoparticles of step S10 are stirred and dispersed in distilled water, and then etched by adding a reagent made of any one of Na ₂ O, KOH, and NaOH reagents or a mixture thereof, and centrifuged for 30 to 80. Method of manufacturing silicon nanoparticles, characterized in that to prepare the etched silicon nanoparticles of ㎚ particle size. According to claim 4,
The method of manufacturing silicon nanoparticles, characterized in that the milling silicon nanoparticles and reagents have a weight ratio of 1:1 to 20. According to claim 4,
The S20 step is a method of manufacturing silicon nanoparticles further comprising ultrasonic cleaning by mixing the etched silicon nanoparticles prepared by centrifugation after etching in water. Step (S100) to prepare a milling silicon nanoparticles of ㎚ particle size by ball milling the silicon microparticles of the particle size,
Step S200 of etching the milling silicon nanoparticles to prepare etched silicon nanoparticles having a particle size of S,
Step (S300) to prepare a silicon nanoparticle dispersion by ball milling while adding distilled water to the etched silicon nanoparticle,
Step (S400) to prepare a colloidal solution by mixing the silicon nanoparticle dispersion, glucose, distilled water and carbon precursor,
Step (S500) for preparing a silicon carbon precursor aggregate by applying heat in an argon gas atmosphere while spraying the colloidal solution as a droplet,
A method of manufacturing carbon coated silicon nanoparticles for a secondary battery, comprising the step (S600) of heat-treating the silicon carbon precursor aggregate in an argon gas atmosphere to prepare carbon coated silicon nanoparticles coated with a carbon precursor. The method of claim 7,
In the step S500, the temperature of the argon gas atmosphere is 180 to 200°C,
Method of manufacturing carbon-coated silicon nanoparticles for a secondary battery, characterized in that the temperature of the argon gas atmosphere in the step S600 is 280 to 320°C. The method of claim 8,
In the step S100, the milling silicon nanoparticles have a particle size of 300 to 800 nm,
The method of manufacturing carbon-coated silicon nanoparticles for a secondary battery, characterized in that the etched silicon nanoparticles in the step S200 have a particle size of 30 to 80 nm. The method of claim 9,
The S100 step is milling the silicon microparticles at 500 to 700 rpm for 2 to 4 hours using a zirconia ball to prepare the milling silicon nanoparticles having a particle size of 300 to 800 nm. Particle manufacturing method. The method of claim 10,
In the S200 step, the milling silicon nanoparticles of the S100 step are stirred and dispersed in distilled water, and then etched by adding a reagent of any one of Na ₂ O, KOH, and NaOH reagents or a mixture thereof, and centrifuged for 30 to 80. Method for producing carbon coated silicon nanoparticles for a secondary battery, characterized in that the etched silicon nanoparticles having a particle size of ㎚ are provided. The method of claim 11,
The milling silicon nanoparticles and reagents are method of producing carbon coated silicon nanoparticles for a secondary battery, characterized in that consisting of a weight ratio of 1:1 to 20. The method of claim 11,
The step S200 is a method of manufacturing carbon coated silicon nanoparticles for a secondary battery, further comprising ultrasonic cleaning by mixing the etched silicon nanoparticles prepared by centrifugation after etching in water.

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