Preparation method of photovoltaic silver powder with adjustable granularity

Abstract

The invention discloses a preparation method of photovoltaic silver powder with adjustable granularity, and belongs to the technical field of silver powder preparation. The method comprises the following steps: (1) preparing a silver source solution; preparing a reducing agent solution; preparing a surface stabilizer solution; (2) mixing the silver source solution and the surface stabilizer solution to obtain a mixed solution, equally dividing the reducing agent solution into at least two parts, adding the reducing agent solution into the mixed solution regularly, adding one part of the reducing agent solution each time, and obtaining a reaction product after the reaction is completed; (3) alternately washing and centrifuging the reaction product by using deionized water and ethanol until a washing solution is neutral, and then drying the washed product to obtain a dried product; and (4) the dried product is subjected to heat treatment in the nitrogen atmosphere, and the silver powder is obtained. In the preparation process of the silver powder, the particle size of the silver powder is regulated and controlled in a simple, efficient and environment-friendly mode, the particle size regulation and control difficulty of the silver powder is remarkably reduced, and precise regulation and control of the silver powder are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of silver powder preparation, and relates to a method for preparing photovoltaic silver powder with adjustable particle size. Background Art

[0002] Photovoltaic silver powder is a key material in the manufacturing process of photovoltaic cells. Its main function is to improve the photoelectric conversion efficiency of solar cells. Silver powder is mainly used in the preparation of solar cell electrodes in the photovoltaic industry. Its excellent conductivity and reflectivity make it the first choice for solar cell electrode materials. With the development of the photovoltaic industry, higher requirements are also put forward for photovoltaic materials.

[0003] The controllability of silver powder particle size has a great impact on its application in the photovoltaic industry. Silver powder with uniform particle size distribution and high stability can make the electronic paste have better performance, so that the electronic paste can meet higher application requirements. Therefore, in the process of preparing silver powder, it is of great significance to precisely control the silver powder particle size and make the silver powder particle size distribution uniform.

[0004] At present, the method for regulating the particle size of silver powder is relatively complicated, requiring the special preparation of seed solution, and precise control of multiple parameters to ensure the accuracy of each parameter. It also needs to be carried out under high temperature conditions. The control of silver powder particle size is difficult and the control process is relatively complicated.

[0005] Therefore, it is necessary to provide a method for preparing photovoltaic silver powder with adjustable strength, to accurately control the particle size of the silver powder during the preparation process, to obtain silver powder with uniform particle size distribution and good stability, so that it can better meet the requirements of the photovoltaic industry. Summary of the invention

[0006] In order to overcome the problems in the background technology, the present invention selects a reducing agent composed of monosaccharides and disaccharides containing free aldehyde groups, so that the reducing agent not only has the ability to reduce silver ions, but also can improve the dispersibility of silver powder during the reaction process. By using polyvinyl alcohol (PVA) with an auxiliary regulating effect, a thin film can be formed on the surface of the silver powder, inhibiting the agglomeration of particles and effectively controlling the particle size growth. At the same time, the way of adding the reducing agent determines the number of nuclei and the growth rate of the silver powder. By adding the reducing agent solution in portions, the particle size of the silver powder can be accurately adjusted. In addition, the present invention can slow down the rapid growth of particles and achieve a more uniform particle size distribution by reducing silver in a low temperature environment.

[0007] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0008] The preparation method comprises the following steps:

[0009] (1) dissolving silver nitrate in water to prepare a silver source solution; dissolving monosaccharide and disaccharide containing free aldehyde groups in water to prepare a reducing agent solution; dissolving polyvinyl alcohol in water to prepare a surface stabilizer solution;

[0010] (2) mixing the silver source solution and the surface stabilizer solution prepared in step (1) to obtain a mixed liquid, and dividing the reducing agent solution into at least two equal parts by volume, adding the reducing agent solution to the mixed liquid at a regular interval, adding one part of the reducing agent solution each time, and obtaining a reaction product after the reaction is completed, stirring the mixed liquid for 10 minutes, and then starting to add the first part of the reducing agent solution;

[0011] (3) washing the reaction product obtained in step (2) alternately with deionized water and ethanol by centrifugation until the washing solution becomes neutral, and then drying the washed product to obtain a dried product;

[0012] (4) heat-treating the dried product obtained in step (3) in a nitrogen atmosphere to obtain silver powder.

[0013] Preferably, in step (1), the concentration of the silver source solution is 0.05-0.5M, the concentration of the reducing agent solution is 50%-70% of the concentration of the silver source solution, and the solid-liquid ratio of polyvinyl alcohol to water in the surface stabilizer solution is polyvinyl alcohol: water = 1g: 20mL.

[0014] Preferably, the mass ratio of the monosaccharide to the disaccharide containing free aldehyde groups is monosaccharide: disaccharide = 1 to 2:1.

[0015] Preferably, in step (1), the monosaccharide includes at least one of glucose and arabinose, and the disaccharide includes at least one of lactose and maltose.

[0016] Preferably, in step (2), the reaction temperature is 30°C.

[0017] Preferably, in step (2), the mass of the surface stabilizer solution is 1% to 2% of the mass of the silver source solution, and the total mass of the reducing agent solution added is 50% to 70% of the mass of the silver source solution.

[0018] Preferably, there is a 5-min interval between the addition of two portions of reducing agent solution.

[0019] Preferably, in step (3), the drying temperature is 40° C. and the drying time is 12 h.

[0020] Preferably, in step (4), the heat treatment temperature is 180° C. and the insulation time is 1 h.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention divides the reducing agent solution into multiple portions, and adds each portion of the reducing agent solution into the reaction system at a fixed time and in a fixed quantity for reaction, thereby effectively avoiding rapid nucleation caused by adding an excessive amount of reducing agent at one time, and ensuring the controllability and stability of the silver powder particle size.

[0023] 2. The present invention uses a specific reducing agent, which not only has the ability to reduce silver ions, but also can improve the dispersibility of silver powder and reduce the agglomeration of silver powder during the reaction process, which helps to reduce the difficulty of controlling the particle size of silver powder.

[0024] 3. The present invention uses polyvinyl alcohol as a surface stabilizer to form a thin film on the surface of the silver powder, inhibit the agglomeration of the silver powder particles, effectively control the particle size growth, further enhance the stability of the silver powder particle size control, and reduce the difficulty of silver powder particle size control.

[0025] 4. The present invention can perform silver reduction in a relatively low temperature environment, which can slow down the particle growth rate and is conducive to uniformly regulating the particle size of the silver powder.

[0026] 5. The reducing agent of the present invention is biocompatible and biodegradable, harmless to the environment, and more environmentally friendly than other chemical reducing agents.

[0027] 6. The present invention realizes precise control of the silver powder particle size during the preparation of photovoltaic silver powder in a simple, efficient and environmentally friendly manner, and is suitable for industrial promotion and application.

[0028] 7. The present invention reduces the ignition loss of silver powder through heat treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a scanning electron microscope image of the silver powder prepared in Example 1 of the present invention.

[0030] Figure 2 This is a scanning electron microscope image of the silver powder prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the described contents.

[0032] Example 1

[0033] In this embodiment, photovoltaic silver powder is prepared according to the following method:

[0034] (1) 8.5 g of silver nitrate (AgNO3) was dissolved in 0.5 L of deionized water to prepare a 0.1 M silver source solution; 4.5 g of monosaccharide and disaccharide containing free aldehyde groups (mass ratio of monosaccharide to disaccharide = 1:1) were dissolved in 0.5 L of deionized water to prepare a 0.05 M reducing agent solution; 0.082 g of PVA was dissolved in 1.64 mL of deionized water to prepare a surface stabilizer solution.

[0035] (2) The silver source solution and the surface stabilizer solution are mixed in a reaction vessel (the mass of the surface stabilizer solution is 1% of the mass of the silver source solution), and the reaction temperature is set to 30° C. A reducing agent solution of 50% of the mass of the silver source solution is taken, and the reducing agent solution is divided into five equal parts, and the reducing agent solution is gradually added to the reaction system in a timed and quantitative manner. During the reaction, the reducing agent solution is added once every 5 minutes to effectively avoid the rapid nucleation caused by the one-time addition of excessive reducing agent, and ensure the stability of the silver powder particle size. After the reaction is completed, a reaction product is obtained, and the first reducing agent solution is added after the silver source solution and the surface stabilizer solution are mixed and stirred for 10 minutes.

[0036] (3) Wash the reaction product obtained by centrifugation with deionized water and ethanol alternately for 3 times, and the washing liquid is neutral. Dry the washed and centrifuged product at 40° C. for 12 hours to obtain a dry product.

[0037] (5) The dried product is placed in a nitrogen atmosphere for heat treatment at 180° C. for 1 hour. After the heat treatment is completed, photovoltaic silver powder is obtained.

[0038] The photovoltaic silver powder prepared in this example was subjected to a scanning electron microscope experiment, and the results are as follows: Figure 1 shown.

[0039] Example 2

[0040] In this embodiment, photovoltaic silver powder is prepared according to the following method:

[0041] (1) 8.5 g of silver nitrate (AgNO3) was dissolved in 1 L of deionized water to prepare a 0.05 M silver source solution; monosaccharides and disaccharides containing free aldehyde groups (mass ratio of monosaccharides to disaccharides = 1.5:1) were dissolved in deionized water to prepare a 0.03 M reducing agent solution; 0.1275 g of PVA was dissolved in 2.55 mL of deionized water to prepare a surface stabilizer solution.

[0042] (2) The silver source solution and the surface stabilizer solution are mixed in a reaction vessel (the mass of the surface stabilizer solution is 1.5% of the mass of the silver source solution), and the reaction temperature is set to 30° C. A reducing agent solution of 60% of the mass of the silver source solution is taken, the reducing agent solution is divided into two equal parts, and the reducing agent solution is gradually added to the reaction system in a timed and quantitative manner. The reducing agent solution is added once every 5 minutes during the reaction process, and a reaction product is obtained after the reaction is completed.

[0043] (3) Wash the reaction product obtained by centrifugation with deionized water and ethanol alternately for 3 times, and the washing liquid is neutral. Dry the washed and centrifuged product at 40° C. for 12 hours to obtain a dry product.

[0044] (5) The dried product is placed in a nitrogen atmosphere for heat treatment at 180° C. for 1 hour. After the heat treatment is completed, photovoltaic silver powder is obtained.

[0045] The photovoltaic silver powder prepared in this example has similar performance to the photovoltaic silver powder in Example 1.

[0046] Example 3

[0047] In this embodiment, photovoltaic silver powder is prepared according to the following method:

[0048] (1) 63.75 g of silver nitrate (AgNO3) was dissolved in 0.75 L of deionized water to prepare a 0.5 M silver source solution; monosaccharides and disaccharides containing free aldehyde groups (mass ratio of monosaccharides to disaccharides = 2:1) were dissolved in deionized water to prepare a 0.35 M reducing agent solution; 1.275 g of PVA was dissolved in 25.5 mL of deionized water to prepare a surface stabilizer solution.

[0049] (2) The silver source solution and the surface stabilizer solution are mixed in a reaction vessel (the mass of the surface stabilizer solution is 2% of the mass of the silver source solution), and the reaction temperature is set to 30° C. A reducing agent solution of 70% of the mass of the silver source solution is taken, and the reducing agent solution is divided into ten equal parts, and the reducing agent solution is gradually added to the reaction system in a timed and quantitative manner. The reducing agent solution is added once every 5 minutes during the reaction process, and a reaction product is obtained after the reaction is completed.

[0050] (3) Wash the reaction product obtained by centrifugation with deionized water and ethanol alternately for 3 times, and the washing liquid is neutral. Dry the washed and centrifuged product at 40° C. for 12 hours to obtain a dry product.

[0051] (5) The dried product is placed in a nitrogen atmosphere for heat treatment at 180° C. for 1 hour. After the heat treatment is completed, photovoltaic silver powder is obtained.

[0052] The photovoltaic silver powder prepared in this example has similar performance to the photovoltaic silver powder in Example 1.

[0053] Comparative Example 1

[0054] This comparative example adopts the same method as Example 1 to prepare photovoltaic silver powder, except that: in this comparative example, the reducing agent solution is not added in portions, but is slowly added dropwise, and the total time for adding the reducing agent is the same as the total time for adding the reducing agent solution in Example 1.

[0055] The photovoltaic silver powder prepared in this comparative example was subjected to a scanning electron microscope experiment, and the results are as follows: Figure 2 shown.

[0056] pass Figure 1 and Figure 2 Comparison shows that the particle size uniformity of the photovoltaic silver powder prepared by the present invention is significantly improved compared with that of the photovoltaic silver powder prepared by comparative example 1, indicating that the photovoltaic silver powder prepared by the present invention can effectively improve the dispersibility of the silver powder, reduce the agglomeration of the silver powder, and has a good effect on the control of the silver powder particle size and the particle size stability.

[0057] In summary, the present invention can achieve relatively precise and stable regulation of the silver powder particle size in a simple, efficient and environmentally friendly manner, so that the prepared photovoltaic silver powder has relatively excellent performance.

Claims

1. A method for preparing photovoltaic silver powder with adjustable particle size, characterized in that: The preparation method comprises the following steps: (1) dissolving silver nitrate in water to prepare a silver source solution; dissolving monosaccharide and disaccharide containing free aldehyde groups in water to prepare a reducing agent solution; dissolving polyvinyl alcohol in water to prepare a surface stabilizer solution; (2) mixing the silver source solution and the surface stabilizer solution prepared in step (1) to obtain a mixed liquid, and dividing the reducing agent solution into at least two equal parts by volume, adding the reducing agent solution to the mixed liquid at a regular interval, adding one part of the reducing agent solution each time, and obtaining a reaction product after the reaction is completed, stirring the mixed liquid for 10 minutes, and then starting to add the first part of the reducing agent solution; (3) washing the reaction product obtained in step (2) alternately with deionized water and ethanol by centrifugation until the washing solution becomes neutral, and then drying the washed product to obtain a dried product; (4) heat-treating the dried product obtained in step (3) in a nitrogen atmosphere to obtain silver powder.

2. The preparation method according to claim 1, characterized in that: In the step (1), the concentration of the silver source solution is 0.05-0.5M, the concentration of the reducing agent solution is 50%-70% of the concentration of the silver source solution, and the solid-liquid ratio of polyvinyl alcohol to water in the surface stabilizer solution is polyvinyl alcohol: water = 1g: 20mL.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the monosaccharide to the disaccharide containing free aldehyde groups is monosaccharide: disaccharide=1-2:

1.

4. The preparation method according to claim 1 or 3, characterized in that: In the step (1), the monosaccharide includes at least one of glucose and arabinose, and the disaccharide includes at least one of lactose and maltose.

5. The preparation method according to claim 1, characterized in that: In the step (2), the reaction temperature is 30°C.

6. The preparation method according to claim 1, characterized in that: In the step (2), the mass of the surface stabilizer solution is 1% to 2% of the mass of the silver source solution, and the total mass of the reducing agent solution added is 50% to 70% of the mass of the silver source solution.

7. The preparation method according to claim 1, characterized in that: There was a 5-min interval between the addition of two portions of reducing agent solution.

8. The preparation method according to claim 1, characterized in that: In the step (3), the drying temperature is 40° C. and the drying time is 12 h.

9. The preparation method according to claim 1, characterized in that: In the step (4), the heat treatment temperature is 180° C. and the insulation time is 1 hour.

Images