High-sphericity-degree and high-compaction silver powder and preparation method thereof

Abstract

The invention provides high-sphericity and high-compaction silver powder and a preparation method thereof, and belongs to the technical field of precious metal powder.The preparation method comprises the following steps that silver nitrate is dispersed in water, and a silver nitrate solution is obtained; dispersing a reducing agent in water, and adjusting the pH value to 7-9 to obtain a reducing agent solution; dispersing a dispersing agent in water to obtain a dispersing agent solution, dispersing ascorbic acid in the dispersing agent solution, and adjusting the pH value to 6-7 to obtain a mixed solution; dispersing a coating agent in absolute ethyl alcohol to obtain a coating agent solution; adding the coating agent solution into the mixed solution, stirring and mixing, simultaneously adding the silver nitrate solution and the reducing agent solution into the mixed solution at a constant speed, and stirring and reacting to obtain silver powder turbid liquid after charging is completed; and filtering, washing and drying the silver powder suspension to obtain the high-sphericity and high-compaction silver powder. Under the synergistic mechanism of'alkaline reduction-neutral stability ', formation of the high-sphericity silver powder can be promoted, and the silver powder can be stably dispersed.

Description

Technical Field

[0001] The present invention relates to the technical field of precious metal powders, and in particular to a high-sphericity and high-tapped silver powder and a preparation method thereof. Background Art

[0002] The morphology of silver powder is a key factor affecting the fluidity, printing performance, conductivity after sintering, and mechanical properties of conductive pastes. In recent years, with the growing demand for high-performance silver powder in photovoltaics, electronic packaging, 5G radio frequency devices and other fields, the preparation technology of spherical silver powder has been continuously optimized. The current industrial methods for preparing high-sphericity silver powder include: liquid-phase chemical reduction method, evaporation-condensation method, atomization method, and plasma method. In the industrial production process, the mainstream method for preparing high-sphericity silver powder is liquid-phase chemical reduction method.

[0003] Patent application CN119140840B discloses a high-sphericity micro-nano silver powder and its preparation method. The application provides a high-sphericity micro-nano silver powder and its preparation method. The method uses sodium borohydride to prepare high-sphericity nanosilver nuclei. Polyvinyl pyrrolidone (PVP) and ascorbic acid are then used to synergistically control the silver powder morphology. Sodium hydroxide is used to promote the rapid hydrolysis of PVP, inducing pseudo-agglomeration and sedimentation of silver particles. Finally, a 50-600nm high-sphericity silver powder is obtained, which is suitable for photovoltaic silver paste and electronic paste. However, sodium borohydride is not suitable for use as a reducing agent in industrial production. This reagent is expensive and produces hydrogen, posing a safety hazard during the production process.

[0004] The invention patent with publication number CN115055690B discloses a spherical polycrystalline silver powder with directional grain aggregation and its preparation method. By adding ascorbic acid in stages at low temperature and adjusting the pH, the silver grains are guided to directional aggregation under the action of a dispersant to form a polycrystalline structure. Although this can improve conductivity, the process requires low temperature control and the tap density is relatively low (5.0-6.0 g / cm 3 ), which will increase energy consumption in large-scale industrial production. Summary of the Invention

[0005] In view of the technical problems existing in the background technology, the present application provides a high-sphericity and high-tapped silver powder and a preparation method thereof, aiming to solve the technical problems of high cost and poor sphericity of the existing silver powder preparation process.

[0006] In a first aspect, the present invention provides a method for preparing a high-sphericity and high-tapped silver powder, comprising the following steps: Dispersing silver nitrate in water to obtain a silver nitrate solution; Dispersing the reducing agent in water and adjusting the pH to 7-9 to obtain a reducing agent solution; Dispersing a dispersant in water to obtain a dispersant solution, dispersing ascorbic acid in the dispersant solution, and adjusting the pH to 6-7 to obtain a mixed solution; dispersing the coating agent in anhydrous ethanol to obtain a coating agent solution; The coating agent solution is added to the mixed solution, and after stirring and mixing, the silver nitrate solution and the reducing agent solution are added to the mixed solution at a uniform speed. After the addition is completed, the mixture is stirred and reacted to obtain a silver powder suspension; The silver powder suspension is filtered, washed and dried to obtain high sphericity and high tap density silver powder.

[0007] In the technical solution of the embodiment of the present application, part of ascorbic acid is added to the dispersant solution of the present invention, and the pH is adjusted to 5-7. The main function of ascorbic acid is to form a buffer solution with the pH regulator, which plays a buffering or stabilizing role in the pH adjustment process of the solution, preventing excessive growth and aggregation of silver powder particles under alkaline conditions; at the same time, the ascorbic acid in the dispersant solution helps control Ag in the early stage of the reaction. + The reduction rate is very low, and it works synergistically with the reducing agent solution to prevent local concentrations from being too high, which can lead to particle agglomeration. Directly adjusting the pH with alkaline substances without adding ascorbic acid will make the solution pH difficult to control.

[0008] The present invention adjusts the reducing agent solution to alkaline (pH 7-9) to accelerate the rapid reduction of silver ions and generate uniform crystal nuclei. - Complexation delays the diffusion of silver ions and inhibits the growth of dendrites. If the pH of the reducing agent solution is not adjusted, the morphology of the obtained silver powder will be crystalline. Subsequently, the steric hindrance and electrostatic repulsion of the dispersant are used to stabilize the particles in a neutral environment (dispersant pH 5-7). The coating agent is pre-adsorbed on the surface of the particles before the reaction to form a protective layer, thereby preparing a silver powder with high sphericity and high tap density. Under this synergistic mechanism of "alkaline reduction-neutral stabilization", it can not only promote the formation of high sphericity silver powder, but also make the silver powder stably dispersed. A longer feeding time and a uniform feeding method are used to make Ag + The release rate is controlled to match the reduction nucleation speed, avoiding polycrystals or dendrites caused by instantaneous high concentration and improving the sphericity of silver powder.

[0009] In some embodiments, the concentration of the silver nitrate solution is 267-400 g / L.

[0010] In some embodiments, the reducing agent is at least one of ascorbic acid, glucose, hydrazine hydrate, ethylene glycol, and formaldehyde; The mass of the first reducing agent is 60% of the mass of silver nitrate.

[0011] In some embodiments, the mass of ascorbic acid is 2% to 8% of the mass of silver nitrate.

[0012] In some embodiments, the dispersant is at least one of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, cetyltrimethylammonium bromide, sodium lauryl sulfate, and Tween-80; The mass of the dispersant is 15%~35% of the mass of silver nitrate.

[0013] In some embodiments, the coating agent is at least one of oleic acid, lauric acid, a silane coupling agent, and stearic acid; The mass of the coating agent is 0.5%~2% of the mass of silver nitrate.

[0014] In some embodiments, the addition time of the silver nitrate solution and the reducing agent solution is 10 to 30 minutes.

[0015] In some embodiments, the stirring reaction time is 5 minutes.

[0016] In the second aspect, the embodiment of the present application provides a high sphericity and high tap density silver powder, the particle size of the high sphericity and high tap density silver powder is 1.52~1.75 μm, and the tap density is 6.01~6.28 g / cm 3 .

[0017] Different from the existing technical solutions, the beneficial effects of this application include: 1. The present invention adjusts the reducing agent solution to alkaline (pH 7-9) to accelerate the rapid reduction of silver ions and generate uniform crystal nuclei, while at the same time - Complexation delays the diffusion of silver ions and inhibits dendrite growth; then, in a neutral environment (dispersant pH 5-7), the particles are stabilized by the steric hindrance and electrostatic repulsion of the dispersant, and a protective layer is formed by pre-adsorbing the coating agent on the particle surface before the reaction to prepare a silver powder with high sphericity and high tap density. Under this synergistic mechanism of "alkaline reduction-neutral stabilization", it can not only promote the formation of high sphericity silver powder, but also make the silver powder stably dispersed. Using a longer feeding time and a uniform feeding method makes Ag + The release rate is controlled to match the reduction nucleation speed, avoiding polycrystals or dendrites caused by instantaneous high concentration and improving the sphericity of silver powder.

[0018] 2. The present invention first adds a coating agent to the mixed solution, followed by the silver nitrate solution and the reducing agent solution. During the initial stages of the silver powder reaction, the coating agent adsorbs onto the surface of the particles, forming a protective molecular layer. This pre-coating modulates the silver powder morphology, inhibiting the random growth of silver particles and promoting the formation of a highly spherical structure. It also prevents agglomeration by reducing the van der Waals forces between particles through steric hindrance or electrostatic repulsion, thus preventing agglomeration. It also stabilizes the reaction environment. During the reduction reaction, the coating agent is evenly distributed in the solution, ensuring immediate stability during particle formation.

[0019] 3. The high sphericity and high tap density micron-sized silver powder prepared by the present invention has a particle size of 1.52-1.75 μm and a tap density of 6.01-6.28 g / cm 3 The micron-sized silver powder with high sphericity and high tap density provided by the present invention has uniform particle size distribution, good dispersibility, and is non-toxic, and is suitable for large-scale industrial batch production, thereby making the photovoltaic silver paste prepared by the high-sphericity and high-tap density micron-sized silver powder in the present invention have excellent conductive properties and printing properties.

[0020] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0022] Figure 1 This is a SEM electron microscope image of the silver powder prepared in Example 3 of this application.

[0023] Figure 2 This is the SEM electron microscope image of the silver powder prepared in Comparative Example 1 of this application.

[0024] Figure 3 This is the SEM electron microscope image of the silver powder prepared in Comparative Example 2 of this application.

[0025] Figure 4 This is the SEM electron microscope image of the silver powder prepared in Comparative Example 3 of this application. DETAILED DESCRIPTION

[0026] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0028] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0029] 1. Preparation method Example 1 A method for preparing high-sphericity and high-tapped silver powder comprises the following steps: Step 1: Prepare the solution Solution A: Dissolve 320g of silver nitrate in 900ml of water and stir to obtain Solution A. Solution B: Dissolve 192 g of ascorbic acid in 900 ml of water, stir well, and then add ammonia water to adjust the pH to 5 to obtain Solution B. Solution C: 48 g of polyethylene glycol was added to 1.6 L of deionized water. After complete dissolution, 16 g of ascorbic acid was added and stirred to dissolve. Sodium carbonate was then added to adjust the pH to 7 to obtain Solution C. Solution D: Add 1g of oleic acid to a beaker, add 10ml of anhydrous ethanol and stir to dissolve to obtain solution D; Step 2: Prepare silver powder: Solution D was first added to solution C. After stirring for 30 seconds, solution A and solution B were added to solution C at the same time. The addition time was set to 15 minutes. Stirring was started and the speed was set to 550 rpm. After the addition was completed, the reaction was continued for 5 minutes. The reaction was completed to obtain a silver powder suspension.

[0030] The obtained silver powder suspension was subjected to solid-liquid separation, and washed and stirred with anhydrous ethanol at a stirring rate of 550 rpm and a stirring time of 10 min. The above operation was repeated until the conductivity of the washing liquid was less than 20 μS / m, thereby obtaining wet silver powder; The wet silver powder was dried at 80°C for 6 hours. After drying and post-processing, high-sphericity and high-tapped micron-sized silver powder was obtained.

[0031] Example 2 A method for preparing high-sphericity and high-tapped silver powder comprises the following steps: Step 1: Prepare the solution Solution A: Dissolve 345g of silver nitrate in 1000ml of water and stir to obtain Solution A. Solution B: Dissolve 207 g of ascorbic acid in 1000 ml of water, stir well, and then add sodium hydroxide to adjust the pH to 9 to obtain Solution B. Solution C: 48 g of polyvinyl alcohol was added to 1.72 L of deionized water. After complete dissolution, 17.2 g of ascorbic acid was added. After stirring to dissolve, aqueous ammonia was added to adjust the pH to 6 to obtain Solution C. Solution D: Take 1g of lauric acid and add it to a beaker. Add 10ml of anhydrous ethanol and stir to dissolve to obtain solution D. Step 2: Prepare silver powder: Solution D was first added to solution C. After stirring for 30 seconds, solution A and solution B were added to solution C at the same time. The addition time was set to 20 minutes. Stirring was started and the speed was set to 550 rpm. After the addition was completed, the reaction was continued for 5 minutes. The reaction was completed to obtain a silver powder suspension.

[0032] The obtained silver powder suspension was subjected to solid-liquid separation, and washed and stirred with anhydrous ethanol at a stirring rate of 550 rpm and a stirring time of 10 min. The above operation was repeated until the conductivity of the washing liquid was less than 20 μS / m, thereby obtaining wet silver powder; The wet silver powder was dried at 80°C for 6 hours. After drying and post-processing, high-sphericity and high-tapped micron-sized silver powder was obtained.

[0033] Example 3 A method for preparing high-sphericity and high-tapped silver powder comprises the following steps: Step 1: Prepare the solution Solution A: Dissolve 320g of silver nitrate in 1200ml of water and stir to obtain solution A. Solution B: Dissolve 173 g of ascorbic acid in 1200 ml of water, stir well, and add sodium hydroxide to adjust the pH to 7 to obtain Solution B. Solution C: 45 g of polyvinyl pyrrolidone was added to 1.76 L of deionized water. After complete dissolution, 16 g of ascorbic acid was added and stirred to dissolve. Ammonium bicarbonate was then added to adjust the pH to 6 to obtain Solution C. Solution D: Add 1g of oleic acid to a beaker, add 10ml of anhydrous ethanol and stir to dissolve to obtain solution D; Step 2: Prepare silver powder: Solution D was first added to solution C. After stirring for 30 seconds, solution A and solution B were added to solution C at the same time. The addition time was set to 15 minutes. Stirring was started and the speed was set to 550 rpm. After the addition was completed, the reaction was continued for 5 minutes. The reaction was completed to obtain a silver powder suspension.

[0034] The obtained silver powder suspension was subjected to solid-liquid separation, and washed and stirred with anhydrous ethanol at a stirring rate of 550 rpm and a stirring time of 10 min. The above operation was repeated until the conductivity of the washing liquid was less than 20 μS / m, thereby obtaining wet silver powder; The wet silver powder was dried at 80°C for 6 hours. After drying and post-processing, high-sphericity and high-tapped micron-sized silver powder was obtained.

[0035] Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that the silver nitrate solution and the reducing agent solution are added in different ways. The specific steps are as follows: Step 1: Prepare the solution Solution A: Dissolve 345g of silver nitrate in 1000ml of water and stir to obtain Solution A. Solution B: Dissolve 207 g of ascorbic acid in 1000 ml of water, stir well, and then add sodium hydroxide to adjust the pH to 9 to obtain Solution B. Solution C: Take 48g of polyvinyl alcohol and add 1.72L of deionized water. After dissolution, add 17.2g of ascorbic acid and stir to dissolve. Then, add ammonia water to adjust the pH to 6 to obtain Solution C. Solution D: Take 1g of lauric acid and add it to a beaker. Add 10ml of anhydrous ethanol and stir to dissolve to obtain solution D. Step 2: Prepare silver powder: Solution D was first added to solution C, and after stirring for 30 seconds, solution A was first added to solution C. After stirring for 3 minutes, solution B was slowly added. The addition time of solution B was 15 minutes. (Comparative addition method) The stirring speed was set to 550 rpm. After the addition was completed, the reaction was continued for 5 minutes. The reaction was completed to obtain a silver powder suspension.

[0036] The obtained silver powder suspension was subjected to solid-liquid separation, and washed and stirred with anhydrous ethanol at a stirring rate of 550 rpm and a stirring time of 10 min. The above operation was repeated until the conductivity of the washing liquid was less than 20 μS / m, thereby obtaining wet silver powder; The wet silver powder was dried at 80°C for 6 hours. After drying and post-processing, high-sphericity and high-tapped micron-sized silver powder was obtained.

[0037] Comparative Example 2 The difference between Comparative Example 2 and Example 3 is that the feeding time is shorter, and the specific steps are as follows: Step 1: Prepare the solution Solution A: Dissolve 320g of silver nitrate in 1200ml of water and stir to obtain solution A. Solution B: Dissolve 173 g of ascorbic acid in 1200 ml of water, stir well, and add sodium hydroxide to adjust the pH to 7 to obtain Solution B. Solution C: 45 g of polyvinyl pyrrolidone was added to 1.76 L of deionized water. After complete dissolution, 16 g of ascorbic acid was added and stirred to dissolve. Then, sodium hydroxide was added to adjust the pH to 6 to obtain Solution C. Solution D: Add 1g of oleic acid to a beaker, add 10ml of anhydrous ethanol and stir to dissolve to obtain solution D; Step 2: Prepare silver powder: Solution D was first added to solution C. After stirring for 30 seconds, solution A and solution B were added to solution C at the same time. The addition time was set to 1 minute. Stirring was started and the speed was set to 550 rpm. After the addition was completed, the reaction was continued for 5 minutes. The reaction was completed to obtain a silver powder suspension.

[0038] The obtained silver powder suspension was subjected to solid-liquid separation, and washed and stirred with anhydrous ethanol at a stirring rate of 550 rpm and a stirring time of 10 min. The above operation was repeated until the conductivity of the washing liquid was less than 20 μS / m, thereby obtaining wet silver powder; The wet silver powder was dried at 80°C for 6 hours. After drying and post-processing, high-sphericity and high-tapped micron-sized silver powder was obtained.

[0039] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that the pH of the dispersant is acidic. The specific steps are as follows: Step 1: Prepare the solution Solution A: Dissolve 320g of silver nitrate in 1200ml of water and stir to obtain solution A. Solution B: Dissolve 173 g of ascorbic acid in 1200 ml of water, stir well, and add sodium hydroxide to adjust the pH to 7 to obtain Solution B. Solution C: 45 g of polyvinyl pyrrolidone was added to 1.76 L of deionized water. After complete dissolution, 16 g of ascorbic acid was added and stirred to dissolve. Then, sodium hydroxide was added to adjust the pH to 3 to obtain Solution C. Solution D: 1 g of oleic acid was added to a beaker and 10 ml of anhydrous ethanol was added and stirred to dissolve to obtain Solution D. Step 2: Prepare silver powder: Solution D was first added to solution C. After stirring for 30 seconds, solution A and solution B were added to solution C at the same time. The addition time was set to 15 minutes. Stirring was started and the speed was set to 550 rpm. After the addition was completed, the reaction was continued for 5 minutes. The reaction was completed to obtain a silver powder suspension.

[0040] The obtained silver powder suspension was subjected to solid-liquid separation, and washed and stirred with anhydrous ethanol at a stirring rate of 550 rpm and a stirring time of 10 min. The above operation was repeated until the conductivity of the washing liquid was less than 20 μS / m, thereby obtaining wet silver powder; The wet silver powder was dried at 80°C for 6 hours. After drying and post-processing, high-sphericity and high-tapped micron-sized silver powder was obtained.

[0041] 2. Test Method 1. Particle size detection method: GB / T 19077-2016 "Particle size analysis by laser diffraction method".

[0042] 2. Burn detection method: (1) Take a certain mass of silver powder sample (accurate to 0.1 mg) and record the initial mass (m0).

[0043] (2) Place the sample in an inert atmosphere (such as nitrogen) or air environment and calcine it at a set temperature (such as 300~500℃) for 1~2 hours to simulate the high temperature exposure conditions in the actual process.

[0044] (3) After cooling, weigh the mass of the calcined sample (m1) and calculate the burning rate: .

[0045] 3. Bulk density and tap density test methods: GB / T 1479.1-2011 Bulk density tester / funnel method; GB / T5162-2021 Tap density tester / tap method.

[0046] 4. Specific surface area detection method: GB / T13390-2008 Specific surface area analyzer / nitrogen adsorption method.

[0047] 3. Analysis of test results of various embodiments and comparative examples The silver powders obtained in Example 3 and Comparative Examples 1 to 3 were examined by scanning electron microscopy, and the SEM images obtained were shown in FIG. Figures 1 to 4 The performance of the silver powders prepared in the embodiments and comparative examples was tested, and the test results are shown in Table 1 below.

[0048] Table 1 Performance data of silver powder obtained in various embodiments and comparative examples

[0049] All three embodiments of the present invention utilize a liquid-phase chemical reduction method to prepare high-sphericity, high-tap density, micron-sized silver powder. This method is performed in an alkaline-neutral environment with simultaneous, long-term addition of feed. This method offers numerous advantages, including a narrow particle size distribution, high sphericity, high tap density, good dispersibility, high purity, and mild reaction conditions. These advantages make this method uniquely suited for preparing high-quality silver powders with high sphericity and high tap density, making it suitable for applications requiring high conductivity and printing properties, such as conductive silver pastes and conductive inks.

[0050] Example 3 in Table 1 is the silver powder with the highest sphericity obtained by this method. The silver powder prepared by this method has a small particle size, D50 is 1.75 μm, and the particle size distribution is uniform. At the same time, it has a high tap density of 6.15 g / cm 3 Comparative Example 1 is not used to add materials at the same time, but first add silver nitrate solution, and then add reducing agent solution to prepare silver powder, from the data in the table and the attached Figure 2 It can be seen that the particle size of the prepared silver powder is too large and the sphericity of the prepared silver powder is very poor; Comparative Example 2 is a comparative test in which the feeding speed is greatly increased and the feeding time is shortened. From the data in the table and the attached Figure 3 It can be seen from the figure that the D90 and D100 particle sizes of the silver powder increase sharply, which indicates that there is agglomeration in the powder. And from the attached figure, it can be seen that dendritic silver powder is generated. This is because the feeding speed is too fast, resulting in instantaneous Ag + The concentration is too high, which leads to the phenomenon; Comparative Example 3 is the effect of using neutral-acid synergistic effect on the preparation of micron-sized silver powder with high sphericity and high tap density. From the data in the table, it can be seen that although the parameters of the silver powder are relatively normal, the attached Figure 4 It can be seen that the morphology of the silver powder is more crystalline and cannot be compared with Examples 1 to 3 in terms of sphericity.

[0051] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solution of the present application, embodiments having substantially the same structure as the technical idea and exerting the same effects are all included in the technical scope of the present application. In addition, within the scope of the subject matter of the present application, various modifications that can be conceived by those skilled in the art to the embodiments, and other methods constructed by combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing high-sphericity and high-tapped silver powder, characterized in that: The steps include: Dispersing silver nitrate in water to obtain a silver nitrate solution; Dispersing the reducing agent in water and adjusting the pH to 7-9 to obtain a reducing agent solution; Dispersing a dispersant in water to obtain a dispersant solution, dispersing ascorbic acid in the dispersant solution, and adjusting the pH to 6 to 7 to obtain a mixed solution; dispersing the coating agent in anhydrous ethanol to obtain a coating agent solution; The coating agent solution is added to the mixed solution, and after stirring and mixing, the silver nitrate solution and the reducing agent solution are added to the mixed solution at a uniform speed. After the addition is completed, the mixture is stirred and reacted to obtain a silver powder suspension; The silver powder suspension is filtered, washed and dried to obtain high-sphericity and high-tapped silver powder.

2. The method for preparing high-sphericity and high-tapped silver powder according to claim 1, wherein: The concentration of the silver nitrate solution is 267-400 g / L.

3. The method for preparing high-sphericity and high-tapped silver powder according to claim 1, wherein: The reducing agent is at least one of ascorbic acid, glucose, hydrazine hydrate, ethylene glycol, and formaldehyde; The mass of the first reducing agent is 60% of the mass of silver nitrate.

4. The method for preparing high-sphericity and high-tapped silver powder according to claim 1, wherein: The mass of the ascorbic acid is 2% to 8% of the mass of the silver nitrate.

5. The method for preparing high-sphericity and high-tapped silver powder according to claim 1, wherein: The dispersant is at least one of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, cetyltrimethylammonium bromide, sodium lauryl sulfate, and Tween-80; The mass of the dispersant is 15% to 35% of the mass of the silver nitrate.

6. The method for preparing high-sphericity and high-tapped silver powder according to claim 1, characterized in that: The coating agent is at least one of oleic acid, lauric acid, a silane coupling agent and stearic acid; The mass of the coating agent is 0.5% to 2% of the mass of silver nitrate.

7. The method for preparing high-sphericity and high-tapped silver powder according to claim 1, wherein: The addition time of the silver nitrate solution and the reducing agent solution is 10 to 30 minutes.

8. The method for preparing high-sphericity and high-tapped silver powder according to claim 1, wherein: The stirring reaction time is 5 minutes.

9. A high sphericity and high tap silver powder, characterized in that: The high sphericity and high tap density silver powder is prepared by the preparation method according to any one of claims 1 to 8, wherein the particle size of the high sphericity and high tap density silver powder is 1.52 to 1.75 μm and the tap density is 6.01 to 6.28 g / cm 3 .

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