KR20230127020A - SiOx carbon coated particles and manufacturing method thereof - Google Patents

Abstract

The present invention relates to SiOx carbon-coated particles and a method for preparing the SiOx carbon-coated particles. More specifically, as a method of recycling silicon oxide (SiOx) fume generated in a silicon growth furnace, it relates to SiOx carbon-coated particles in which fume collected from a silicon growth furnace is coated with carbon and a method for manufacturing the same .

Description

SiOx carbon coated particles and manufacturing method thereof {SiOx carbon coated particles and manufacturing method thereof}

The present invention relates to SiOx carbon-coated particles and a method for preparing the SiOx carbon-coated particles. More specifically, as a method of recycling silicon oxide (SiOx) fume generated in a silicon growth furnace, it relates to SiOx carbon-coated particles in which fume collected from a silicon growth furnace is coated with carbon and a method for manufacturing the same .

A solar cell is a device that converts the energy of light into electricity using the photovoltaic effect. Solar power is an attractive green energy source because it is sustainable and generates only non-polluting by-products. Accordingly, much research is being done to develop solar cells with improved efficiencies while continuing to lower material and manufacturing costs.

Solar cells are classified into silicon, solar cells, thin-film solar cells, dye-sensitized solar cells, and organic polymer solar cells, depending on their constituent materials. It can be said to be the most popular 　 solar cell because it is higher than that of a battery and technology to lower the manufacturing cost continues to be developed.

In general, the electrodes of a solar cell are formed on the surface of a wafer by coating, patterning, and firing an electrode paste. A conductive paste for an electrode of a solar cell typically includes a "conductive" powder, a glass frit, an organic medium, and additives. To be formed into patterns that carry electrical signals on a substrate, the “conductive” paste is printed onto the substrate as a linear or other pattern and then fired.

The challenges to be solved in the conductive paste are largely divided into printability, adhesiveness, and electrical conductivity. That is, a pattern must be printed with a desired line width through a desired printing method, and the electrodes formed by the conductive paste must be attached to the substrate with durability to have high adhesive strength and low resistance. Printability requires research on a composition having physical properties suitable for line widths that are miniaturized and the corresponding printing technology, and the size of “conductive” powder or the properties of organic medium are mainly important for this. Adhesion requires research to stably attach the conductive paste composition to the substrate for a long time, and the composition of the glass frit is mainly important for this. In addition, electrical conductivity requires research on line resistance and ohmic contact according to line width reduction, and the composition of "conductive" powder and frit is mainly important for this.

The conductive paste composition is a technical solution to achieve printability, adhesiveness, and electrical conductivity, which are technical elements such as conductive powder, glass frit, and organic medium, which have antagonistic effects on each other to create a balanced solution for each technical element. Technology development is required.

Meanwhile, Japanese Laid-Open Patent Publication No. 2005-243500 includes an organic binder, a solvent, a glass frit, conductive powder, and at least one metal selected from Ti, Bi, Zn, Y, In, and Mo, or a metal compound thereof. A conductive paste in which an average particle diameter of a metal or a metal compound thereof is 0.001 μm or more and less than 0.1 μm is disclosed.

Japanese Laid-open Patent No. 2005-243500

The present invention is a method of recycling silicon oxide (SiOx) fume generated in a silicon growth furnace, and to provide SiOx carbon-coated particles in which fume collected from a silicon growth furnace is coated with carbon and a method for manufacturing the same.

In order to solve the above problem,

The present invention provides SiOx carbon-coated particles obtained by recycling silicon oxide (SiOx) fumes generated in a silicon growth furnace and coating the silicon oxide (SiOx) fumes with carbon.

The SiOx carbon coating particles may have a multi-pore structure.

In addition, the present invention comprises the steps of collecting fume (fume) generated in the silicon growth furnace; Homogenizing the collected fume; preparing a slurry by mixing the homogenized fume with a fluororesin and dissolving it in a solvent; and carbonizing the slurry after drying to form SiOx carbon-coated particles.

The fume may include silicon oxide (SiOx) fume.

The homogenized fume and the fluororesin may be mixed in a ratio of 0.5:1 to 3:1.

The fluororesin is a carbon precursor, and is selected from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinylfluoride (PVF), and combinations thereof. may be selected.

The carbonizing step may be heat treatment at 600 to 800° C. under an inert gas atmosphere.

After the carbonization step, a step of preparing a powder by milling may be further included.

SiOx carbon coated particles according to the present invention can be prepared by coating fume collected in a silicon growth furnace with a fluororesin as a carbon precursor. The SiOx carbon coating particles recycle silicon oxide (SiOx) fumes generated from previously discarded silicon growth furnaces, enabling eco-friendly waste treatment and securing domestic and foreign manufacturing technology for solar cells or secondary battery anode materials that are urgently needed for localization. It can also be used as a conductive additive.

In addition, the recycling technology in the form of extracting silicon from the sludge generated in the existing silicon ingot processing process has the disadvantage of difficult post-treatment because it is in the form of sludge, but the SiOx carbon coating particles according to the present invention are SiOx generated in the silicon growth furnace Since fume can be obtained as dried powder rather than sludge, post-treatment is easier than sludge recycling technology.

In addition, the SiOx carbon coating particles according to the present invention have a feature that allows them to enter the domestic market as well as overseas markets with price competitiveness based on low manufacturing cost.

1 is a schematic diagram showing steps for preparing SiOx carbon-coated particles of the present invention.
Figure 2 is a schematic diagram showing a manufacturing process of SiOx carbon coated particles in one embodiment of the present invention.
3 (a) and (b) are SEM images showing samples heat-treated under conditions of a flow rate of 1 LPM according to an embodiment of the present invention.
4 (a) and (b) are SEM images showing samples heat-treated for 2 hours according to an embodiment of the present invention.
5 (a) and (b) are SEM images showing samples heat-treated at 700° C. according to an embodiment of the present invention.
6 (a) to (d) show the results of EDS mapping and EDS spectrum analysis of the particles of FIG. 5.
7 (a) to (c) show TEM images and elemental distributions of carbon-coated silica particles according to an embodiment of the present invention.
8 shows the change in discharge capacity according to the change in the mixing ratio of silica particles and PVDF in the manufacture of carbon-coated silica particles according to an embodiment of the present invention.
FIG. 9 shows a change in resistance characteristics according to a change in the mixing ratio of silica particles and PVDF in the manufacture of carbon-coated silica particles according to an embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In the present invention, the term "comprises" or "has" is 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.

In the present invention, "silicon oxide (SiOx) fume" is obtained by collecting and filtering silicon oxide (SiOx) contained in waste gas generated when manufacturing silicon (Si), ferrosilicon (FeSi), silicon alloy, etc. with a dust collector As a micro-silica particle, it means a material applied to various fields such as high-strength cement and concrete products, refractories, and other substitutes for asbestos. It is known as an essential material for manufacturing recent underwater concrete or concrete requiring durability, especially high-strength concrete. Among the physical properties of silicon oxide fume, the color is generally gray, and there are also black and white colors. The difference in color is mainly determined by the amount of carbon, although it is affected by the content of iron.

Hereinafter, the present invention will be described in detail.

The present invention provides SiOx carbon-coated particles obtained by recycling silicon oxide (SiOx) fumes generated in a silicon growth furnace and coating the silicon oxide (SiOx) fumes with carbon.

The SiOx carbon coating particles may have a multi-pore structure. This may be caused by using a fluororesin as a carbon precursor when carbon is coated on the silicon oxide fume.

The SiOx carbon coating particle according to the present invention contains silicon particles and can be used as an anode material.

The SiOx carbon coating particles according to the present invention can be used as SiOx carbon coating particles for conductive adhesives used in shingled modules with reduced resistance due to direct contact between solar cells. In addition, it can be used as an additive for a finger line through which electrons generated during the solar cell power generation process move.

The recycling technology in the form of extracting silicon from the sludge generated in the existing silicon ingot processing process has the disadvantage of difficult post-treatment because it is in the form of sludge, but the SiOx carbon coating particles according to the present invention are SiOx fume generated from the silicon growth furnace Since it can be obtained as dried powder rather than sludge, it has the advantage of being easier to post-process than sludge recycling technology.

In addition, the SiOx carbon coating particles according to the present invention have a feature that allows them to enter the domestic market as well as overseas markets with price competitiveness based on low manufacturing cost.

In addition, the present invention comprises the steps of collecting fume (fume) generated in the silicon growth furnace; Homogenizing the collected fume; preparing a slurry by mixing the homogenized fume with a fluororesin and dissolving it in a solvent; and carbonizing the slurry after drying to form SiOx carbon-coated particles. 1 is a schematic diagram showing steps for preparing the SiOx carbon-coated particles.

Referring to FIG. 1, SiOx carbon coated particles according to the present invention can be prepared by coating fumes collected in a silicon growth furnace with a fluororesin as a carbon precursor. The SiOx carbon coating particles are environmentally friendly waste treatment by recycling silicon oxide (SiOx) fumes generated from previously discarded silicon growth furnaces, and it is possible to secure domestic and foreign manufacturing technologies for anode materials that urgently need to be localized. Can be used as an additive.

Specifically, in the present invention, fume generated in the silicon growth furnace may be collected by a dust collector connected to the silicon growth furnace. After homogenizing the collected fume, the homogenized fume may be mixed with a fluororesin as a carbon precursor, dissolved in a solvent, and then dried.

Homogenization of the collected fume is a process of equalizing the particle size of the collected particles, and may be a process of minimizing the variation of powders having various particle size distributions, and may include a milling method.

The milling may be performed by any one of ball milling, attrition milling, and gyro ball milling.

The fume may include silicon oxide (SiOx) fume.

The homogenized fume and the fluororesin may be mixed in a ratio of 0.5:1 to 3:1. For example, the homogenized fume and fluororesin are 0.5: 1 to 1.5: 1, 0.5: 1 to 1: 1, 1: 1 to 3: 1, 1: 1 to 2: 1, 1: 1 to 1.5: It may be mixing in a ratio of 1 or 1.5:1 to 2:1.

The fluororesin is a carbon precursor, and is selected from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinylfluoride (PVF), and combinations thereof. may be selected. In addition, the fluororesin is a carbon precursor for preparing the particles into carbon composite particles, and may include a polymer in which carbon and fluorine are polymerized.

In the fluororesin, fluorine is discharged in the heat treatment process to exhibit an etching effect, so that impurities in silicon oxide can be removed, and accordingly, a process of purifying the impurities can be omitted. The etching is performed by generating hydrogen fluoride (HF) from the fluorine resin by heat during the heat treatment process, and reacting the HF and silicon oxide to form SiF ₄ and H ₂ O.

Carbon composite particles prepared using the fluororesin as a carbon precursor may have a multi-pore structure.

The solvent for mixing and dissolving the homogenized fume and the fluororesin may include an organic solvent, and more specifically, an organic solvent having a higher carbon number than acetone. For example, the organic solvent may include N-methyl pyrrolidone (NMP).

After the drying, for example, carbonization may be performed by heat treatment at 600 to 800° C. under an inert gas atmosphere in an electric furnace. For example, the heat treatment may be heat treatment at 600 to 750 °C, 600 to 700 °C, 600 to 650 °C, 650 to 800 °C, 700 to 800 °C, or 750 to 800 °C.

The heat treatment may be performed for 1 to 5 hours. For example, the heat treatment may be performed for 2 to 3 hours.

The inert gas may include one or more of Ar, N ₂ , Ne, or He.

After the carbonizing step, a step of preparing powder by milling the carbonized fume may be further included. After the carbonization, the carbonized powder is formed into a lump and can be prepared in a powdered state through the milling, which is an essential step to use the SiOx carbon coating particles as a conductive additive.

The milling may be performed by any one of ball milling, attrition milling, and gyro ball milling.

Hereinafter, the present invention will be described in more detail through examples and the like according to the present invention, but the scope of the present invention is not limited by the examples presented below.

[Example]

manufacturing example

2 is a schematic diagram showing a manufacturing process of SiOx carbon-coated particles of this production example.

Referring to Figure 2, in order to coat carbon on silica particles homogenized by ball milling silica fume, polyvinylidene fluoride (PVDF), a source for carbon coating, and N-methylpyrrolidone, a solvent for dissolving PVDF (N-methyl-2-pyrolidone, NMP) was mixed, dried, and heat-treated at 600 to 800 ° C. for 2 to 4 hours while flowing nitrogen, an inert gas. After heat treatment, milling was performed to prepare silica particles that became agglomerates in a powder state while being mixed with PVDF, which is a polymer, during the carbonization process.

Since the carbonization depends on the flow rate of the nitrogen gas and the heat treatment temperature, first, the mixing ratio of silica and PVDF is set to 1: 1 to determine the heat treatment temperature and gas flow rate, and only the heat treatment temperature and gas flow rate are changed while analyzing the carbide did

Experimental Example

In order to select the carbonization conditions of the carbide, the experiment was performed under the process conditions shown in Table 1 with reference to several previous studies.

A total of 27 samples were made by selecting variables according to each condition, and conditions for forming a layered carbon coating layer were found through SEM and TEM analysis.

heat treatment time
[hr] inert gas
Flow rate [LPM] heat treatment temperature
[℃] 2 0.5 650 2.5 One 700 3 1.5 750

3 (a) and (b) are SEM images of one of the samples. In the sample prepared under the condition of a nitrogen gas flow rate of 1 LPM or more, particles whose surface was not covered with a carbon coating layer were confirmed. Considering that even if the amorphous carbon layer covers the surface of the particle, the particle surface is not visible, it was determined that the coating layer was not stable under a flow rate condition of 1 LPM or more.

According to the above experiment, after fixing the nitrogen gas flow rate to 0.5 LPM, parameters were optimized by coating carbon on ㎛-sized spherical silica particles to make it easier to check the formation conditions of the carbon coating layer. ㎛-sized particles are larger than NM-sized silica particles, so when observing the coating layer during SEM analysis, they have the advantage of being more clearly distinguished than NM-sized particles and making it easier to see the surface in detail. It was applied to nanometer-sized particles.

As shown in (a) and (b) of FIG. 3, the samples prepared under the flow conditions except for the flow rate conditions (1 LPM or more) did not require a detailed examination of the surface of the coating layer because the collapse of the coating layer was clear, but the samples prepared under the other conditions A surface analysis was required because the coating layer was covered.

4 (a) and (b) are SEM pictures showing one of the particles of the sample made with the heat treatment time of 2 and 2.5 hours, and it was confirmed that the carbon coating layer was formed on the surface, but partially peeled off. As shown in the particles in (a) and (b) of FIG. 3 , it was confirmed that the coating layer was not completely peeled off and was partially peeled off.

Among the samples with a heat treatment time of 3 hours, some samples as shown in (a) and (b) of FIG. 4 were found even at a temperature of 650 ° C, and it was determined that there was no problem with the coating at a temperature of 700 ° C or higher.

Figures 5 (a) and (b) are SEM images showing the particles of the samples under the conditions of heat treatment temperature of 700 ℃ or more. It was confirmed that the carbon layer completely covered the particle surface. The difference between 700 ° C and 750 ° C is expected to be a difference in crystalline and amorphous or the thickness of the formed layer, not the formation of the coating layer.

In order to confirm the ratio of carbon coated on the surface of the particles shown in (a) and (b) of FIG. 5, EDS analysis was performed on the particles, but the two particles were judged to be similar when considering the error range.

Figures 6 (a) to (d) show the EDS analysis results of the particles shown in Figure 5 (a) and (b). As shown in (a) to (d) of FIG. 6, the values of the two particles were similar, so it was determined that there would be no difference in thickness or crystalline formation of the coating layer.

When comparing the two samples, since they were numerically similar, the heat treatment temperature was selected under the condition of 700 ° C, which uses less energy in terms of manufacturing unit cost. It was determined to be 700°C.

The manufacturing process conditions determined above were applied to silica particles having a size of 3 μm to confirm the etching effect of PVDF.

7 (a) to (c) are TEM images (a and b) showing conductive particles prepared by carbonizing 3 μm-sized silica particles with a heat treatment time of 3 hours, a nitrogen gas flow rate of 0.5 LPM, and a heat treatment temperature of 700 ° C. It shows the elemental distribution (c). As shown in FIG. 7, it can be seen that the inside of the large particle (a) is etched to create an empty space, and not only the particle (a) with a size of about 300 nm but also the particle (b) with a size of about 70 nm has a similar shape. It can be seen that particles are formed. It was confirmed that the outside of the original particle was etched by hydrogen fluoride and the particle size was reduced.

As shown in Chemical Formula 1 below, HF is generated from the fluororesin including PVDF by heat during the treatment process, and the HF and SiO ₂ react to change into SiF ₄ and H ₂ O.

[Formula 1]

In addition, as shown in (c) of FIG. 7, it was confirmed that carbon coated the particles through the presence of carbon in the element distribution.

Figure 8 shows the change in discharge capacity according to the change in the mixing ratio of silica particles and PVDF in the above preparation example. As samples, silica particles and silica:PVDF mixing ratios of 1:1 and 3:1 were used to measure carbon-coated particles. As shown in FIG. 8, it was found that the higher the mixing ratio of the silica particles, the higher the initial discharge capacity.

9 shows a change in resistance characteristics according to a change in the mixing ratio of silica particles and PVDF in the above Preparation Example. As samples, silica particles and silica:PVDF mixing ratios of 1:1 and 3:1 were used to measure carbon-coated particles. As shown in FIG. 9, it was found that the higher the mixing ratio of silica, the lower the resistance value, and this was because the electrical conductivity was improved and the stability was improved.

Claims (8)

By recycling the silicon oxide (SiOx) fume generated in the silicon growth furnace,
SiOx carbon-coated particles obtained by coating the silicon oxide (SiOx) fume with carbon.
According to claim 1,
The SiOx carbon coated particles are SiOx carbon coated particles, characterized in that the multi-pore structure.
Collecting fume generated from a silicon growth furnace;
Homogenizing the collected fume;
preparing a slurry by mixing the homogenized fume with a fluororesin and dissolving it in a solvent; and
Method for producing SiOx carbon-coated particles comprising the step of carbonizing the slurry after drying to form SiOx carbon-coated particles.
According to claim 1,
The fume is a method for producing SiOx carbon coated particles, characterized in that it comprises silicon oxide (SiOx) fume.
According to claim 1,
The homogenized fume and the fluororesin are mixed in a ratio of 0.5: 1 to 3: 1, characterized in that the manufacturing method of SiOx carbon coating particles.
According to claim 1,
The fluororesin is a carbon precursor, and is selected from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinylfluoride (PVF), and combinations thereof. Method for producing SiOx carbon coated particles, characterized in that selected.
According to claim 1,
In the carbonization step,
Method for producing SiOx carbon coated particles, characterized in that heat treatment at 600 to 800 ℃ in an inert gas atmosphere.
According to claim 1,
After the carbonization step,
Method for producing SiOx carbon-coated particles further comprising the step of milling to prepare a powder.