Method for preparing spherical silver powder for silver paste through TOPCon battery LECO technology

Abstract

The invention relates to the technical field of silver powder preparation, in particular to a method for preparing spherical silver powder for silver paste through a TOPCon battery LECO technology, and aims to solve the problems that at present, the spherical silver powder for preparing the silver paste is poor in dispersity, the particle size is difficult to effectively control, and finally printing and conductivity of the spherical silver powder for the silver paste are affected. The method comprises the following steps: preparing a silver nitrate solution, a reducing agent solution and a dispersing agent solution; preparing a pH adjusting solution, adding the pH adjusting solution into a reducing agent solution, adding a dispersing agent solution into a silver nitrate solution, fully and uniformly stirring, quickly pouring the reducing mixed solution into the silver nitrate solution in parts by weight under a stirring condition to obtain silver powder slurry, and washing, drying and separating the silver powder slurry to obtain the spherical silver powder. The superfine silver powder is good in dispersity, controllable in particle size, narrow in particle size distribution, good in sintering activity and high in tap density, and the printing performance and the conductivity of the spherical silver powder for the silver paste are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of silver powder preparation technology, and specifically to a method for preparing spherical silver powder for silver paste using TOPCon battery LECO technology. Background Technology

[0002] Due to their higher photoelectric conversion efficiency, TOPCon cells have become the mainstream photovoltaic product. Their structural and process design requires finding a balance between the surface passivation layer and the metal contact to reduce electron-hole recombination while maintaining good current collection. LECO technology allows for high-quality metal contact points without compromising the passivation layer properties. It can precisely and locally disrupt the passivation layer and promote electron transport between the metal and silicon. LECO can lower the optimal sintering temperature for cell metallization by 20-40°C, resulting in a higher open-circuit voltage (Voc) without a decrease in the fill factor (FF), thus achieving a significant breakthrough in improving the cell's photoelectric conversion efficiency by 0.2%-0.5%. As TOPCon cells and LECO technology mature, the front-side metallization paste has changed from traditional silver-aluminum paste to pure silver paste, placing more stringent requirements on the rheological properties, printability, and optimal sintering temperature of the silver paste. Therefore, the dispersibility, particle size and distribution, and sintering activity of the silver powder, the conductive functional phase of the silver paste, also require further optimization and improvement. Summary of the Invention

[0003] This invention provides a method for preparing spherical silver powder for silver paste using TOPCon battery LECO technology, in order to solve the problems mentioned above.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing spherical silver powder for silver paste using TOPCon battery LECO technology includes the following steps: Step 1: Prepare AgNO3 solution A, with a mass concentration of 5%-20% AgNO3.

[0005] Step 2: Prepare reducing agent solution B, with a mass concentration of 10%-20%.

[0006] Step 3: Prepare dispersant solution C by dissolving the dispersant in alcohol. The amount of dispersant used is 0.5%-5% of the mass fraction of AgNO3. Then, mix the mixture of dispersant and alcohol with deionized water to obtain dispersant solution C.

[0007] Step 4: Prepare a pH adjustment solution and add it to the reducing agent solution B in step 2 to obtain a mixed reducing solution with a pH value of 1-9.

[0008] Step 5: Add the dispersant solution C from step 3 to the AgNO3 solution A from step 1, and stir thoroughly to obtain a mixed AgNO3 solution.

[0009] Step 6: Divide the mixed reducing solution from Step 4 into ≥3 portions, and quickly pour the mixed reducing solution into the mixed AgNO3 solution from Step 5 under stirring conditions. The addition time of the mixed reducing solution is ≤10s, and the reaction temperature is controlled at 20℃-40℃ to obtain silver powder slurry.

[0010] Step 7: Separate the silver powder slurry from Step 6, wash and dry it at a temperature of 60℃-90℃ to obtain spherical silver powder with a particle size D50 of 1.0μm-3.0μm and a specific surface area of ​​0.4m². 2 / g-1.0 m 2 / g, tap density ≥5.5g / cm³ 3 .

[0011] Furthermore, the reducing agent solution B in step 2 is composed of one or a combination of two of ascorbic acid, formaldehyde, hydrazine hydrate, sodium borohydride, and nicotinamide.

[0012] Further, the dispersant solution C in step 3 is composed of one or more of polyvinylpyrrolidone, Tween-40, oleic acid, oleylamine, sodium dodecylbenzenesulfonate, rosin, octanoic acid and Triton-100.

[0013] Furthermore, the pH adjustment solution in step 4 is one of nitric acid, sodium hydroxide, or potassium hydroxide.

[0014] Furthermore, the spherical silver powder is composed of several nanoscale primary particles aggregated into secondary particles, and the secondary particles have excellent monodispersity and uniformity.

[0015] The present invention has the following beneficial effects: This invention provides a method for preparing spherical silver powder for silver paste using TOPCon battery LECO technology. The method includes preparing a silver nitrate solution, a reducing agent solution, and a dispersant solution; preparing a pH adjustment solution and adding it to the reducing agent solution; then adding the dispersant solution to the silver nitrate solution and stirring thoroughly; finally, rapidly pouring the reduced mixture into the silver nitrate solution in portions under stirring to obtain a silver powder slurry. After washing, drying, and separation, spherical silver powder is obtained. This method results in ultrafine silver powder with good dispersibility, controllable particle size, narrow particle size distribution, good sintering activity, and high tap density, greatly improving the printing performance and conductivity of the spherical silver powder for silver paste. It solves the problems of poor dispersibility and difficulty in effectively controlling particle size in current silver paste preparation methods, which ultimately affect the printing and conductivity performance of the spherical silver powder for silver paste. Attached Figure Description

[0016] Figure 1 This is a scanning electron microscope image of the spherical silver powder prepared in Example 1 of the present invention.

[0017] Figure 2 This is a scanning electron microscope image of the spherical silver powder prepared in Example 2 of the present invention.

[0018] Figure 3 This is a scanning electron microscope image of the spherical silver powder prepared in Example 3 of the present invention.

[0019] Figure 4 This is a scanning electron microscope image of the spherical silver powder prepared in Comparative Example 1 of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 Preparation of AgNO3 solution A: Dissolve 200g AgNO3 in 2L of deionized water, stir thoroughly, and keep the temperature constant to 30℃.

[0022] Prepare reducing agent solution B: Dissolve 100g of ascorbic acid in 500mL of deionized water, stir thoroughly, and keep the temperature constant to 30℃.

[0023] To prepare dispersant solution C: Dissolve 2g of oleic acid in 20mL of alcohol, then add 30mL of deionized water and stir thoroughly.

[0024] Preparation of pH adjustment solution: Prepare 5% wt dilute nitric acid solution, add it dropwise to reducing agent solution B, and obtain a mixed reducing solution with a pH of 3.

[0025] Add the prepared dispersant solution C to the AgNO3 solution A and stir thoroughly.

[0026] The prepared mixed reducing solution was divided into four equal portions, and simultaneously and rapidly poured into an AgNO3 solution containing dispersant solution C under stirring. The mixture was stirred until no Ag was detected in the reaction solution. + The reaction was deemed complete at a certain time. After solid-liquid separation and washing, the mixture was dried at 60℃ for 8 hours, then crushed and sieved to obtain ultrafine spherical silver powder. The scanning electron microscope image of the obtained spherical silver powder is shown below. Figure 1 As shown.

[0027] Example 2 Preparation of AgNO3 solution A: Dissolve 300g of silver nitrate in 2L of deionized water, stir thoroughly, and keep the temperature constant to 30℃.

[0028] Prepare reducing agent solution B: Dissolve 150g of ascorbic acid in 750mL of deionized water, stir thoroughly, and keep the temperature constant to 30℃.

[0029] To prepare dispersant solution C: Dissolve 2g of oleic acid in 20mL of alcohol, then add 30mL of deionized water and stir thoroughly.

[0030] Preparation of pH adjustment solution: Prepare a 5% wt sodium hydroxide solution, add it dropwise to reducing agent solution B, and obtain a mixed reducing solution with a pH of 6.

[0031] Add the prepared dispersant solution C to the AgNO3 solution A and stir thoroughly.

[0032] The prepared mixed reducing solution was divided into four equal portions, and simultaneously and rapidly poured into an AgNO3 solution containing dispersant solution C under stirring. The mixture was stirred until no Ag was detected in the reaction solution. + The reaction was determined to be complete at a certain time. After solid-liquid separation and washing, the powder was dried at 80℃ for 8 hours, crushed, and sieved to obtain ultrafine spherical silver powder. The scanning electron microscope image of the obtained spherical silver powder is shown below. Figure 2 As shown.

[0033] Example 3 Preparation of AgNO3 solution A: Dissolve 200g of silver nitrate in 2L of deionized water, stir thoroughly, and keep the temperature constant to 30℃.

[0034] Prepare reducing agent solution B: Dissolve 100g of ascorbic acid in 500mL of deionized water, stir thoroughly, and keep the temperature constant to 30℃.

[0035] To prepare dispersant solution C: Dissolve 1g of oleic acid and 1g of Tween-40 in 20mL of alcohol, then add 30mL of deionized water and stir thoroughly.

[0036] Preparation of pH adjustment solution: Prepare 5% wt dilute nitric acid solution, add it dropwise to reducing agent solution B, and obtain a mixed reducing solution with a pH of 9.

[0037] Add the prepared dispersant solution C to the AgNO3 solution A and stir thoroughly.

[0038] The prepared mixed reducing solution was divided into four equal portions, and simultaneously and rapidly poured into an AgNO3 solution containing dispersant solution C under stirring. The mixture was stirred until no Ag was detected in the reaction solution. + The reaction was determined to be complete at a certain time. After solid-liquid separation and washing, the powder was dried at 90℃ for 8 hours, crushed, and sieved to obtain ultrafine spherical silver powder. The scanning electron microscope image of the obtained spherical silver powder is shown below. Figure 3 As shown.

[0039] Comparative Example 1 Preparation of AgNO3 solution A: Dissolve 200g of silver nitrate in 2L of deionized water, stir thoroughly, and keep the temperature constant to 30℃.

[0040] Prepare reducing agent solution B: Dissolve 100g of ascorbic acid in 500mL of deionized water, stir thoroughly, and keep the temperature constant to 30℃.

[0041] Preparation of pH adjustment solution: Prepare 5% wt dilute nitric acid solution, add it dropwise to reducing agent solution B, and obtain a mixed reducing solution with a pH of 1.

[0042] Under stirring conditions, the mixed reducing solution was quickly poured into an AgNO3 solution containing a dispersant, and the mixture was stirred until no Ag was detected in the reaction solution. + The reaction was determined to be complete at a certain time. After solid-liquid separation and washing, the powder was dried at 80℃ for 8 hours, crushed, and sieved to obtain ultrafine silver powder. The scanning electron microscope image of the obtained spherical silver powder is shown below. Figure 4 As shown.

[0043] After comparing Examples 1-3 and Comparative Example 1, the physical properties of the spherical silver powder for silver paste are shown in Table 1.

[0044] Table 1. Physical Indicator Tests The application performance data of the obtained spherical silver powder for silver paste are shown in Table 2.

[0045] Table 2. Application Performance Data

Claims

1. A method for preparing spherical silver powder for silver paste using a LECO technique for a TOPCon cell, characterized by, The process comprises the following steps: Step 1, preparing AgNO3 solution A, the mass concentration of AgNO3 is 5%-20%; Step 2, preparing reducing agent solution B, the mass concentration of reducing agent is 10%-20%; Step 3, preparing dispersant solution C, dispersing the dispersant in alcohol, the amount of dispersant is 0.5%-5% of the mass fraction of AgNO3, then mixing the mixture of dispersant and alcohol with deionized water to obtain dispersant solution C; Step 4, preparing pH adjusting solution and adding it into the reducing agent solution B of step 2 to obtain mixed reducing liquid, the pH value of the mixed reducing liquid is 1-9; Step 5, adding the dispersant solution C of step 3 into the AgNO3 solution A of step 1, stirring thoroughly to obtain mixed AgNO3 solution; Step 6, dividing the mixed reducing liquid of step 4 into ≥3 parts, and quickly pouring the mixed reducing liquid into the mixed AgNO3 solution of step 5 under stirring, the adding time of the mixed reducing liquid is ≤10s, the reaction temperature is controlled at 20℃-40℃, and silver powder slurry is obtained. Step 7, the silver powder slurry of step 6 is separated and washed and dried, the drying temperature is 60-90℃, finally spherical silver powder is obtained, the particle size D50 of the spherical silver powder is 1.0-3.0μm, the specific surface area is 0.4-0.8m 2 / g, the tap density is ≥5.5g / cm 2 / g, the tap density is ≥5.5g / cm 3 .

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