Solar positive silver powder with high dispersibility and high tap density and method for manufacturing the same

Abstract

The application discloses solar positive silver powder with high dispersity and high tap density, which is prepared by decomposing silver iodide under blue light and inducing silver single element, has high dispersity and high tap density, and can well meet the fine line and low resistance requirements of solar positive electrodes. The application also discloses a manufacturing method of the solar positive silver powder, which comprises the following steps: preparing a system A solution, adding a solution, preparing a system B solution after blue light irradiation, mixing the system A solution and the system B solution, adding a flocculating agent to obtain silver powder precipitation, washing, drying and crushing the silver powder after solid-liquid separation, and obtaining the solar positive silver powder. Only the characteristics of silver iodide decomposition under light are used, silver single element is directly obtained through physical light irradiation, nucleation sites are provided for subsequent solar positive silver powder growth, and compared with chemical reduction, silver nucleus is obtained, so that the method is more simple and efficient.

Description

Technical Field

[0001] This invention belongs to the field of precious metal powder material preparation technology, specifically, it relates to a solar positive silver powder with high dispersibility and high tap density and its manufacturing method. Background Technology

[0002] Photovoltaic power generation, as one of the major environmentally friendly renewable energy sources, has experienced rapid development and widespread application in recent years. Over the past decade, the production of photovoltaic modules has achieved an average annual growth rate of over 30%, with the average growth rate exceeding 50% in the last three years. Industry experts even predict that by 2060, photovoltaic installed capacity may be 70 times its current level. Silver paste is a crucial material in solar cell manufacturing. Silver powder and glass powder in the paste are sintered onto the solar cell to form silver electrodes, which collect and transport current. The performance parameters of the silver powder directly affect the conversion efficiency of the solar cell.

[0003] With the development of photovoltaic technology, solar cell front electrodes are becoming increasingly finer, requiring lower resistance. This necessitates that solar cell front silver powder possess both high dispersibility and high tap density. Currently, domestically produced silver powder still lags behind imported silver powder in terms of electrical performance and stability, and its industrial production capacity also lags behind that of foreign countries. Reference document CN108714699B, "A method for preparing active silver powder using silver sulfide induction and the silver powder obtained therefrom," discloses the controlled preparation of monodisperse silver powder by adding Na2S to form Ag2S. In this method, Ag2S is reduced to elemental silver with different morphologies and particle sizes in the early stages of the reaction. This process is sensitive to conditions, difficult to control, and can easily lead to differences in the performance of the silver powder. Furthermore, the comparative documents CN105436517B, "A method for preparing metal powder by inducing production using nano-seeds", and CN110434355B, "A method for preparing spherical silver powder with high tap density and high dispersibility", propose adding nano-silver seeds or nuclei to induce the production of metal powder, but do not mention the process for effectively controlling the quality of nano-silver seeds, which may also lead to differences in the performance of silver powder.

[0004] Therefore, there is an urgent need to develop a simple, stable, and controllable method for producing highly dispersed, high-tap-density solar positive silver powder. Summary of the Invention

[0005] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a solar positive silver powder with high dispersibility and high tap density and its preparation method.

[0006] To solve the above-mentioned technical problems, the objective of this invention can be achieved through the following technical solutions:

[0007] The first aspect of this invention is a highly dispersible, high-tap-density solar-grade silver powder, which is prepared by blue light decomposition of silver iodide and induction of elemental silver. The laser particle size D50 of this solar-grade silver powder ranges from 1 to 2.5 μm, preferably from 1.2 to 1.8 μm, and the specific surface area ranges from 0.2 to 0.6 cm². 2 / g, preferably in the range of 0.32-0.48cm 2 / g.

[0008] The solar-grade silver powder of the first embodiment of this invention has the following characteristics: the particle size distribution (D90-D10) / D50 ≤ 1.5 and Dm / D50 ≤ 1.4, where Dm is the average particle size of the silver powder observed by scanning electron microscopy, and the tap density ranges from 6.0 to 6.9 g / cm³. 3 .

[0009] The solar positive silver powder of the first aspect of the present invention has the following characteristics: the solar positive silver powder has a spherical or near-spherical morphology.

[0010] The second aspect of this invention is a method for manufacturing highly dispersed, high-tap-density solar positive silver powder, comprising:

[0011] Step 1: Dissolve the surfactant in water, and then dissolve the reducing agent in water. The concentration of the surfactant is controlled at 5-40 g / L, the concentration of the reducing agent is controlled at 70-250 g / L, and the solution temperature is controlled at 20-40℃ to obtain system A.

[0012] Step 2: Dissolve silver nitrate in water to obtain a silver nitrate aqueous solution with a mass concentration of 80-350 g / L. Then, add sodium iodide or potassium iodide solution dropwise under light-protected conditions to react and obtain silver iodide. The molar concentration of silver iodide in the solution is 5-100 mmol / L. Control the solution temperature at 20-40℃ and irradiate with blue light for 5-30 min to decompose silver iodide into elemental silver, obtaining system B.

[0013] Step 3: Mix system A with system B. After the reaction is complete, add 0.2-2 wt% flocculant of silver powder to precipitate the silver powder.

[0014] Step 4: After separating the solid and liquid components of the silver powder, wash, dry and crush it to obtain solar positive silver powder.

[0015] Another feature of this third-party invention based on the second aspect is that the surfactant in step 1 is a nonionic polymer, preferably one or two of polyethylene glycol, gelatin, and polyvinylpyrrolidone, and more preferably polyvinylpyrrolidone; the surfactant in step 1 is a nonionic polymer, preferably one or two of polyethylene glycol, gelatin, and polyvinylpyrrolidone, and more preferably polyvinylpyrrolidone.

[0016] The fourth aspect of this invention, based on the second aspect, is further characterized in that the reducing agent in step 1 is one of ascorbic acid, sodium ascorbate, glucose, and sodium borohydride, preferably ascorbic acid.

[0017] The fifth aspect of this invention, based on the second aspect, is further characterized in that the blue light wavelength range in step 2 is 400–480 nm, preferably 410–430 nm. Blue light has high energy in the spectrum and is essentially harmless to the human body. The blue light intensity range is 200–800 mW / cm². 2 The preferred light intensity range is 400–600 mW / cm². 2 Too low or too high light intensity is not conducive to controlling the growth of elemental silver.

[0018] The sixth aspect of this invention, based on the second aspect, is further characterized in that the mixing of system A and system B in step 3 is one of three mixing methods: adding system A to system B dropwise, adding system B to system A dropwise, or adding system A and system B to the reactor simultaneously. The preferred mixing method is adding system A and system B to the reactor simultaneously, with the solution drop rate controlled at 200–5000 ml / min.

[0019] The sixth aspect of the invention based on the second aspect is further characterized in that the flocculant is one of tetradecanoic acid, hexadecanoic acid, oleic acid, stearic acid, and sodium stearate.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention produces silver iodide using sodium iodide or potassium iodide, taking advantage of the light-decomposing property of silver iodide. Elemental silver is obtained directly through physical light irradiation, providing nucleation sites for subsequent solar-powered silver powder growth. Compared to obtaining silver nuclei through chemical reduction, this is a simpler and more efficient method.

[0022] 2. The blue light irradiation method for generating elemental silver in this invention is essentially a photo-induced method, which enables the generated elemental silver to slowly transform into silver nuclei with similar crystal form and morphology under the action of light. Photo-induction has a certain correction and shaping effect, ensuring the quality of elemental silver, which is conducive to generating solar positive silver powder with high dispersion and high tap density, and also increases batch-to-batch stability.

[0023] 3. The wavelength range, light intensity, and light exposure time of the blue light in the technical solution of this invention will affect the final physicochemical properties of elemental silver. These conditions are relatively simple and controllable in production. The final particle size of silver powder can be adjusted by simple parameter changes, making it easy to achieve industrial production.

[0024] 4. The solar-grade silver powder obtained by the technical solution of the present invention has a particle size distribution of (D90-D10) / D50≤1.5 and Dm / D50≤1.4, where Dm is the average particle size of silver powder observed by scanning electron microscopy, and the tap density ranges from 6.0 to 6.9 g / cm3. These parameters can well meet the requirements of fine wire and low resistance of solar front electrode. Attached Figure Description

[0025] Figure 1 This is a SEM image of the silver powder prepared in Example 1.

[0026] Figure 2 This is a SEM image of the silver powder prepared in Example 2.

[0027] Figure 3 This is a SEM image of the silver powder prepared in Example 3.

[0028] Figure 4 The image shows a SEM image of the silver powder prepared in Comparative Example 1. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] (1) Dissolve 10g of polyvinylpyrrolidone in 1000g of water, then dissolve 200g of sodium ascorbate in water, and control the solution temperature at 25℃ to obtain system A;

[0032] (2) Dissolve 150g of silver nitrate solution in 1000g of water to obtain a silver nitrate aqueous solution with a mass concentration of 150g / L. Then, add potassium iodide solution dropwise under light-protected conditions to react and obtain silver iodide. The molar concentration of silver iodide in the mixed solution is 20mmol / L. Control the solution temperature at 25℃ and use a light source with a wavelength of 430nm and an irradiation intensity of 600mW / cm². 2 Irradiation with blue light for 20 minutes decomposed silver iodide into elemental silver, yielding system B;

[0033] (3) Add system A to system B dropwise at a rate of 600 ml / min. After the reaction is complete, add 1.5 wt% of hexadecanoic acid (by weight of silver powder) to precipitate the silver powder.

[0034] (4) After the silver powder is separated into solid and liquid, it is washed, dried and crushed to obtain solar positive silver powder.

[0035] The obtained silver powder laser-etched particle size D50 is 1.6 μm, and the specific surface area ranges from 0.42 cm². 2 / g, silver powder particle size distribution (D90-D10) / D50=1.36 and Dm / D50=1.38, where Dm is the average particle size of silver powder observed by scanning electron microscopy, and the tap density range is 6.4g / cm3. For example Figure 1 As shown, the obtained solar-grade silver powder has a spherical morphology.

[0036] Example 2

[0037] (1) Dissolve 60g of polyethylene glycol in 2000g of water, then dissolve 300g of ascorbic acid in water, and control the solution temperature at 40℃ to obtain system A;

[0038] (2) Dissolve 430g of silver nitrate solution in 2000g of water to obtain a silver nitrate aqueous solution with a mass concentration of 215g / L. Then, add sodium iodide solution dropwise under light-protected conditions to react and obtain silver iodide. The molar concentration of silver iodide in the solution is 90mmol / L. The solution temperature is controlled at 40℃, and a light intensity of 300mW / cm is used. 2 Irradiation with blue light for 10 minutes decomposes silver iodide into elemental silver, yielding system B;

[0039] (3) System A and System B are simultaneously added dropwise to the reactor at a rate of 800 ml / min. After the reaction is completed, 0.8 wt% of oleic acid is added to the silver powder to precipitate the silver powder.

[0040] (4) After the silver powder is separated into solid and liquid, it is washed, dried and crushed to obtain solar positive silver powder.

[0041] The obtained silver powder had a laser-etched particle size D50 of 1.2 μm and a specific surface area of ​​0.46 cm².2 / g, silver powder particle size distribution (D90-D10) / D50=1.40 and Dm / D50=1.23, where Dm is the average particle size of silver powder observed by scanning electron microscopy, and the tap density range is 6.1g / cm3. For example Figure 2 As shown, the obtained solar-grade silver powder has a spherical morphology.

[0042] Example 3

[0043] (1) Dissolve 300g of polyvinylpyrrolidone in 15kg of water, then dissolve 3kg of ascorbic acid in water, and control the solution temperature at 30℃ to obtain system A.

[0044] (2) Dissolve 4 kg of silver nitrate in 12 kg of water to obtain a silver nitrate aqueous solution with a mass concentration of 333.3 g / L. Then, under light-protected conditions, add sodium iodide solution dropwise to react and obtain silver iodide. The molar concentration of silver iodide in the solution is 50 mmol / L. Control the solution temperature at 30℃ and use a light source with a wavelength of 470 nm and an irradiation intensity of 500 mW / cm². 2 Irradiation with blue light for 15 minutes decomposes silver iodide into elemental silver, yielding system B.

[0045] (3) Add system B to system A at a rate of 1000 ml / min. After the reaction is complete, add stearic acid of 1 wt% of the silver powder mass to precipitate the silver powder.

[0046] (4) After the silver powder is separated into solid and liquid, it is washed, dried and crushed to obtain solar positive silver powder.

[0047] The obtained silver powder had a laser-guided particle size D50 of 1.5 μm, a specific surface area ranging from 0.44 cm² / g, a particle size distribution of (D90-D10) / D50 = 1.44 and Dm / D50 = 1.35, where Dm is the average particle size of the silver powder observed by scanning electron microscopy, and a tap density ranging from 6.3 g / cm³. Figure 3 As shown, the obtained solar-grade silver powder has a spherical morphology.

[0048] Comparative Example 1

[0049] 1) Dissolve 300g of polyvinylpyrrolidone in 15kg of water, then dissolve 3kg of ascorbic acid in water, and control the solution temperature at 30℃ to obtain system A.

[0050] (2) Dissolve 4 kg of silver nitrate in 12 kg of water to obtain a silver nitrate aqueous solution with a mass concentration of 333.3 g / L. Then, add sodium iodide solution dropwise under the dark to react and obtain silver iodide. The molar concentration of silver iodide in the solution is 50 mmol / L. Control the solution temperature at 30℃ to obtain system B.

[0051] (3) Add system B to system A at a rate of 1000 ml / min. After the reaction is complete, add stearic acid of 1 wt% of the silver powder mass to precipitate the silver powder.

[0052] (4) After the silver powder is separated into solid and liquid, it is washed, dried and crushed to obtain solar positive silver powder.

[0053] The obtained silver powder had a laser-guided particle size D50 of 1.8 μm, a specific surface area ranging from 0.54 cm² / g, a particle size distribution of (D90-D10) / D50 = 1.65 and Dm / D50 = 1.91, where Dm is the average particle size of the silver powder observed by scanning electron microscopy, and a tap density ranging from 5.4 g / cm³. Figure 4 As shown, the obtained solar-grade silver powder has a spherical morphology.

[0054] The particle size and tapping performance of silver powder in Examples 1-3 and Comparative Example 1 were analyzed, and the numerical results are shown in Table 1.

[0055]

[0056] Table 1. Analysis of particle size and tapping performance of solar-grade silver powder prepared in Examples 1-3 and Comparative Example 1.

[0057] As clearly shown in Table 1, even when comparing individual powder characteristic values, the solar positive silver powder obtained using the above examples exhibits higher dispersibility compared to silver powder manufactured using conventional methods. Furthermore, the high film density overlap effect caused by the fine powder particles within the solar positive silver powder reduces the resulting conductor resistance. These findings sufficiently demonstrate that the solar positive silver powder manufactured using the method of the present invention can effectively meet the requirements for finer lines and lower resistance in solar front electrodes.

[0058] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this invention should be considered within the scope of protection of this invention.

Claims

1. A solar-grade silver powder with high dispersibility and high tap density, characterized in that, This solar-grade positive silver powder is prepared by decomposing silver iodide with blue light and inducing the formation of elemental silver. The particle size distribution of the solar-grade silver powder is (D90-D10) / D50≤1.5 and Dm / D50≤1.4, where Dm is the average particle size of the silver powder observed by scanning electron microscopy, and the tap density ranges from 6.0 to 6.9 g / cm³. 3 The method for manufacturing the solar positive silver powder includes the following steps: Step 1: First, dissolve the surfactant in water, then dissolve the reducing agent in water. The concentration of the surfactant is controlled at 5-40 g / L, the concentration of the reducing agent is controlled at 70-250 g / L, and the solution temperature is controlled at 20-40℃ to obtain system A. Step 2: Dissolve silver nitrate solution in water to obtain a silver nitrate aqueous solution with a mass concentration of 80-350 g / L. Then, add sodium iodide or potassium iodide solution dropwise under light-protected conditions to react and obtain silver iodide. The molar concentration of silver iodide in the solution is controlled at 5-100 mmol / L, and the solution temperature is controlled at 20-40℃. Irradiate with blue light for 5-30 min to decompose silver iodide into elemental silver, obtaining system B. Step 3: Mix system A obtained in step 1 with system B obtained in step 2. After the reaction is complete, add flocculant with a mass of 0.2-2 wt% silver powder to precipitate the silver powder. Step 4: After separating the solid and liquid components of the silver powder obtained in Step 3, wash, dry and crush it to obtain solar positive silver powder.

2. The highly dispersible, high-tap-density solar positive silver powder as described in claim 1, characterized in that, The laser-coated positive silver powder has a particle size D50 ranging from 1 to 2.5 μm and a specific surface area ranging from 0.2 to 0.6 cm². 2 / g.

3. The highly dispersible, high-tap-density solar positive silver powder as described in claim 2, characterized in that, The laser-coated positive silver powder has a particle size D50 ranging from 1.2 to 1.8 μm and a specific surface area ranging from 0.32 to 0.48 cm². 2 / g.

4. The highly dispersible, high-tap-density solar positive silver powder according to claim 1, characterized in that, The surfactant mentioned in step 1 is a nonionic polymer, and is one or two of polyethylene glycol, gelatin, and polyvinylpyrrolidone.

5. The highly dispersible, high-tap-density solar positive silver powder according to claim 1, characterized in that, The reducing agent mentioned in step 1 is one of ascorbic acid, sodium ascorbate, glucose, and sodium borohydride.

6. The highly dispersible, high-tap-density solar positive silver powder according to claim 1, characterized in that, The blue light wavelength range in step 2 is 400-480nm, and the blue light intensity range is 200-800mW / cm². 2 .

7. The highly dispersible, high-tap-density solar positive silver powder according to claim 1, characterized in that, The blue light wavelength range mentioned in step 2 is 420-430nm, and the blue light intensity range is 400~600mW / cm². 2 .

8. The highly dispersible and high-tap-density solar positive silver powder according to claim 1, characterized in that, The mixing of system A and system B in step 3 is one of three mixing methods: adding system A to system B dropwise, adding system B to system A dropwise, or adding system A and system B to the vessel simultaneously. The drop rate of the solutions in system A and system B is controlled between 200-5000 ml / min.

9. The highly dispersible and high-tap-density solar positive silver powder according to claim 1, characterized in that, The flocculant in step 3 is one of myristic acid, hexadecanoic acid, oleic acid, stearic acid, and sodium stearate.

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