KR102285734B1 - Conductive additive for solar cell module and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a conductive additive for a solar cell module and a method for manufacturing the conductive additive for a solar cell module and, more particularly, to a conductive additive for a solar cell module coated with carbon fumes collected from a silicon growth furnace and a method for manufacturing the same, as a method of recycling silicon oxide (SiOx) fume generated in a silicon growth furnace. Recycling technology in the form of extracting silicon from the sludge generated in the existing silicon ingot processing process is in the form of sludge, so post-treatment is difficult. However, according to the conductive additive for a solar cell module of the present invention, the SiOx fume generated in the silicon growth furnace is obtained as dried powder, not sludge, so that the post-treatment is easier than sludge recycling technology.

Description

Conductive additive for solar cell module and manufacturing method thereof

The present invention relates to a conductive additive for a solar cell module and a method for manufacturing the conductive additive for a solar cell module. More specifically, as a method of recycling silicon oxide (SiOx) fume generated in a silicon growth furnace, a conductive additive for a solar cell module in which the fume collected in a silicon growth furnace is coated with carbon and a method for manufacturing the same it's about

A solar cell is a device that converts light energy into electricity using the photovoltaic effect. Solar power is an attractive green energy source because it produces only sustainable and unpolluted by-products. Therefore, many studies are being conducted to develop solar cells with improved efficiency while continuously lowering material and manufacturing costs.

Solar cells are classified into silicon 　 solar cells, thin film 　 solar cells, dye-sensitized solar cells, organic polymers and solar cells according to their constituent materials. Crystalline silicon solar cells account for most of the total production of solar cells worldwide and have different efficiency. It can be said that it is the most popular solar cell because it is higher than the battery and technology to keep the manufacturing cost lower is being developed.

In general, an electrode of a solar cell is formed on a wafer surface by application of an electrode paste, patterning, and firing. Conductive pastes for electrodes of solar cells typically include a conductive powder, glass frit, an organic medium, and additives. The conductive paste is printed onto the substrate as a linear or other pattern and then fired to form a pattern that carries electrical signals on the substrate.

The tasks to be solved in the conductive paste are largely divided into printability, adhesiveness, and electrical conductivity. That is, the pattern should be printed with a desired line width through a desired printing method, and the electrode, etc. formed by the conductive paste should be attached to the substrate while having durability, so that the adhesive force should be high, and it is necessary to lower the resistance. It is necessary to study the printability of the composition having properties suitable for the line width to be refined and the corresponding printing technology. Adhesiveness requires research to ensure that the conductive paste composition is stably attached to the substrate for a long time, and for this, the composition of the glass frit is mainly important. In addition, the electrical conductivity requires a study for line resistance and ohmic contact according to the reduction in line width. For this, the composition of the powder and frit is mainly important.

In the conductive paste composition, the technical elements for achieving the technical solutions such as printability, adhesion, and electrical conductivity, conductive powder, glass frit, and an organic medium have an antagonistic effect on each other to achieve a balanced effect on each technical element. Technology development is required.

Meanwhile, Japanese Patent Laid-Open No. 2005-243500 discloses an organic binder, a solvent, a glass frit, a conductive powder, and at least one metal selected from Ti, Bi, Zn, Y, In and Mo or a metal compound thereof. The conductive paste to be used WHEREIN: The electrically conductive paste whose average particle diameter of a metal or its metal compound is 0.001 micrometer or more and less than 0.1 micrometer is disclosed.

Japanese Patent Laid-Open No. 2005-243500

The present invention is a method of recycling silicon oxide (SiOx) fumes generated in a silicon growth furnace. To provide a conductive additive for a solar cell module in which the fume collected in a silicon growth furnace is coated with carbon and a method for manufacturing the same do.

In order to solve the above problem,

The present invention comprises the steps of collecting fumes (fume) generated in a silicon growth furnace; homogenizing the collected fume; mixing the homogenized fume with a polymer, dissolving it in a solvent, and drying the mixture; and carbonizing after drying.

The fume may include silicon oxide (SiOx) fume.

The polymer is a carbon source, polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), epoxy, polypropylene (PP), PEET, glucose (glucose), cellulose (cellulose), and may be selected from the group consisting of combinations thereof.

The carbonizing may be heat-treating at 500 to 1,000° C. under an inert gas atmosphere.

After the carbonizing step, it may further include the step of preparing a powder by milling.

In addition, the present invention provides a conductive additive for a solar cell module manufactured according to the above manufacturing method.

The conductive additive for a solar cell module according to the present invention can be prepared by coating fumes collected in a silicon growth furnace with carbon. The conductive additive for solar cell module recycles silicon oxide (SiOx) fume generated in the silicon growth furnace that was previously discarded, so that waste can be treated in an eco-friendly manner, and domestic and foreign manufacturing technology for anode materials urgently needed for localization can be secured. , it can be used as a conductive additive for solar cell modules.

In addition, the conventional recycling technology in the form of extracting silicon from the sludge generated in the silicon ingot processing process has a disadvantage in that post-treatment is difficult because it is in the form of sludge. Since SiOx fume can be obtained as dried powder rather than sludge, it has the advantage of easier post-treatment than sludge recycling technology.

In addition, the conductive additive for a solar cell module according to the present invention has the feature of being able to enter the domestic market as well as the overseas market with price competitiveness based on low manufacturing cost.

1 (a) and (b) are SEM images showing a sample heat-treated at a flow rate of 1 LPM according to an embodiment of the present invention.
2 (a) and (b) are SEM images showing a sample heat-treated for 2 hours according to an embodiment of the present invention.
3 (a) and (b) are SEM images showing a sample heat-treated at 700° C. according to an embodiment of the present invention.
4 (a) to (d) show the results of EDS mapping and EDS spectrum analysis of the particles of FIG. 3 .
5 (a) and (b) show TEM images of silica particles having a carbon-coated nm-size silica particle and a layered carbon layer according to an embodiment of the present invention.

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

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

In the present invention, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

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 refers to a material applied to various fields such as high-strength cement and concrete products, refractory materials, and replacement of other asbestos. Recently, it is known as an essential material for the production of underwater concrete or concrete that requires durability, especially high-strength concrete. Among the physical properties of silicon oxide fume, the color is generally gray, and there are black and white ones. The color difference is mainly determined by the amount of carbon although it is affected by the iron content.

Hereinafter, the present invention will be described in detail.

The present invention comprises the steps of collecting fumes (fume) generated in a silicon growth furnace; homogenizing the collected fume; mixing the homogenized fume with a polymer, dissolving it in a solvent, and drying the mixture; and carbonizing after drying. The mixing ratio between the homogenized fume and the polymer may range from 0.5:1 to 1:3.

The conductive additive for a solar cell module according to the present invention can be prepared by coating fumes collected in a silicon growth furnace with carbon. The conductive additive for solar cell module recycles silicon oxide (SiOx) fume generated in the silicon growth furnace that was previously discarded, so that waste can be treated in an eco-friendly manner, and domestic and foreign manufacturing technology for anode materials urgently needed for localization can be secured. , it can be used as a conductive additive for solar cell modules.

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

The homogenization of the collected fumes is a process of equalizing the particle size of the collected particles, and may be a process of minimizing the deviation 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 polymer is a carbon source, polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), epoxy (Epoxy), polypropylene (PP), polyetheretherketone (Polyetheretherketone, PEEK) ), glucose (glucose), cellulose (cellulose), and may be selected from the group consisting of combinations thereof. In addition, the polymer may include a carbon polymer or a polymer, but may not be limited thereto.

The solvent for mixing and dissolving the homogenized fume and the polymer may include an organic solvent, 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, it may be carbonized by heat treatment at 500 to 1,000° C. under an inert gas atmosphere in an electric furnace. For example, the heat treatment may be heat treatment at 500 to 800 °C, 500 to 600 °C, 600 to 1,000 °C, 700 to 1,000 °C, 800 to 1,000 °C, 600 to 800 °C, or 700 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, the method may further include milling the carbonized fume to prepare a powder. After the carbonization, the carbonized powder is formed into a lump and can be prepared in a powdered state through the milling, and is a step that is essential to use as a conductive additive for a solar cell module.

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

In addition, the present invention provides a conductive additive for a solar cell module manufactured according to the above manufacturing method.

The conductive additive for a solar cell module according to the present invention can be used as a conductive additive for a conductive adhesive used in a shingled module 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 power generation process of a solar cell move.

The conventional recycling technology in the form of extracting silicon from the sludge generated in the silicon ingot processing process has a disadvantage in that post-treatment is difficult because it is in the form of sludge. Since fume can be obtained as dried powder rather than sludge, it has the advantage of easier post-treatment than sludge recycling technology.

In addition, the conductive additive for a solar cell module according to the present invention has the feature of being able to enter the domestic market as well as the overseas market with price competitiveness based on low manufacturing cost.

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

To coat carbon on silica particles homogenized with silica fume by ball milling, polyvinylidene fluoride (PVDF), a source for carbon coating, and N-methylpyrrolidone (N-methyl-2- pyrolidone, NMP) was mixed, dried, and heat-treated at 600 to 800° C.) for 2 to 4 hours while flowing nitrogen as an inert gas. After heat treatment, milling was performed to prepare silica particles that were agglomerated while being mixed with PVDF, a polymer, in a powder state when subjected to a carbonization process.

Since carbonization varies depending on the flow rate of the nitrogen gas and the heat treatment temperature, first, in order to determine the heat treatment temperature and the flow rate of the gas, the mixing ratio of silica and PVDF is fixed to 1:1, and the carbide is produced while only the heat treatment temperature and the flow rate of the gas are changed. analyzed.

Experimental example

In order to select the carbonization conditions of the carbide, the process conditions shown in Table 1 were tested with reference to several previous studies.

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

Heat treatment time [hr] Inert gas flow [LPM] Heat treatment temperature [℃] 2 0.5 650 2.5 One 700 3 1.5 750

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

According to the above experiment, after fixing the nitrogen gas flow rate to 0.5 LPM, variable optimization was performed by coating carbon on spherical silica particles having a size of μm to make it easier to check the formation conditions of the carbon coating layer. ㎛ size particles are larger than nm size silica particles, so when observing the coating layer during SEM analysis, they are clearly distinguished than nm size particles and have the advantage that it is easy to see the surface in detail. It was applied to particles of nanometer size.

As shown in (a) and (b) of Fig. 1 (a) and (b), there was no need to examine the surface of the coating layer in detail for the sample prepared under flow conditions except Surface analysis was required as the coating layer was covered.

2 (a) and (b) are SEM photographs showing one of the particles of the sample made with heat treatment times of 2 and 2.5 hours, and it was confirmed that a carbon coating layer was formed on the surface, but partly peeled off. It could be confirmed that the coating layer was not completely peeled off like the particles of FIGS. 1 (a) and (b), but was partially peeled off.

Some of the samples as shown in (a) and (b) of FIG. 2 were found even in samples having a temperature of 650 °C among the heat treatment time of 3 hours, and it was determined that there was no problem in coating at a temperature of 700 °C or higher.

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

EDS analysis was performed on the particles to confirm the ratio of carbon coated on the particle surface shown in (a) and (b) of FIGS.

4 (a) to (d) show the results of EDS analysis of the particles shown in FIGS. 3 (a) and (b). As shown in (a) to (d) of Figure 4, the numerical values of the two particles are similar, so it was determined that there would be no difference in the thickness or crystalline formation of the coating layer.

Since the two samples were numerically similar when compared, the heat treatment temperature was selected as a condition of 700 °C that uses less energy in terms of manufacturing cost. It was determined to be 700°C.

The determined manufacturing process conditions were applied to silica particles having a size of nm.

5 (a) and (b) are TEM images of silica particles having a size of nm, carbonized at a heat treatment time of 3 hours, a nitrogen gas flow rate of 0.5 LPM, and a heat treatment temperature of 700°C. As shown in FIG. 5, in FIG. 5(a), two aggregated particles of about 300 nm in size are seen, and in FIG. It was possible to see what was written on the The black dots are silica, and the film that is brighter than the outer silica has a layered structure with a carbon layer, indicating that the silicas are aggregated inside the carbon layer.

Since the size of the non-agglomerated particles was targeted to be 100 nm or less, it was determined that the size of the carbon-coated particles was manufactured to the desired size.

Claims (6)

Collecting fumes (fume) generated in the silicon growth furnace;
homogenizing the collected fume;
mixing the homogenized fume with a polymer, dissolving it in a solvent, and drying the mixture; and
A method of manufacturing a conductive additive for a solar cell module, comprising the step of carbonizing after drying.
The method of claim 1,
The fume is a method of manufacturing a conductive additive for a solar cell module, characterized in that it comprises silicon oxide (SiOx) fume.
The method of claim 1,
The polymer is a carbon source, polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), epoxy, polypropylene (PP), polyetheretherketone (PEEK) ), glucose (glucose), cellulose (cellulose), and a method of manufacturing a conductive additive for a solar cell module, characterized in that selected from the group consisting of combinations thereof.
The method of claim 1,
The carbonizing step is,
Method for producing a conductive additive for a solar cell module, characterized in that heat treatment at 500 to 1,000 ℃ under an inert gas atmosphere.
The method of claim 1,
After the carbonizing step,
Method for producing a conductive additive for a solar cell module further comprising the step of preparing a powder by milling.
A conductive additive for a solar cell module prepared according to any one of claims 1 to 5.

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