Spherical silver powder with rough surface structure and its preparation method and application

Abstract

The present invention discloses a quasi-spherical silver powder with a rough surface structure, a preparation method, and an application thereof. The preparation method comprises the following steps: separately preparing a silver nitrate solution, a reducing agent solution, and a dispersant solution, wherein the reducing agent solution contains an organic doping auxiliary prepared by mixing a polyol, a polyoxyethylene ether, a salt, and an alkali; simultaneously adding the silver nitrate solution and the reducing agent solution dropwise to the dispersant solution, stirring and reacting after the addition is completed to obtain a reaction solution; settling the reaction solution, decanting the supernatant, and then adding anhydrous ethanol for dispersion. After the dispersion is completed, solid-liquid separation, washing, and drying are performed to obtain a quasi-spherical silver powder with a rough surface structure. Based on the spherical silver powder, the present invention successfully prepares a monodisperse silver powder with a rough surface structure. The individual silver powder particles are quasi-spherical in shape, and a roughened structure exists on the particle surface. The silver powder is mainly used in the front slurry of solar photovoltaic cells and has good electrical properties and linearity.

Description

Technical Field

[0001] The present invention relates to the field of metal powder material preparation, and in particular to spherical silver powder with a rough surface structure, a preparation method and application thereof. Background Art

[0002] With the development of the photovoltaic industry and the emerging electronics industry, electronic conductive pastes are increasingly widely used. As the most important conductive component, the performance of metal powder has a crucial impact on the quality of electronic paste. Due to its good conductivity and relatively low price, metallic silver has become the main raw material for preparing powder for paste. The photovoltaic cell market is changing very rapidly. From 2023 to April 2024, photovoltaic front silver with a twin structure was favored by the market. However, since April, the market has changed dramatically, twin photovoltaic front silver has cooled, and monodisperse silver powder with a rough surface has become the mainstream. Combined with the rapid development of TOPCon technology, it is expected that roughened monodisperse silver powder will attract widespread attention for a long time to come.

[0003] In industrial production, chemical reduction has become the main method for producing silver powder due to its advantages such as mild reaction conditions, low production cost and simple process route. Chinese patent CN111618316A discloses a surface-modified silver powder and its coating preparation method. This patent can effectively control the roughness of the powder surface by adjusting the pH of the additive solution, thereby obtaining monodisperse silver powders with different specific surface areas and different organic coating amounts. However, although the addition of a pH regulator can make the surface of the powder particles smooth or rough, as the pH value of the solution changes from strongly acidic to strongly alkaline, the powder particles obviously gradually transition from a smooth surface state to a rough surface state, and the dispersion effect changes from excellent to poor.

[0004] Therefore, there is an urgent need to provide more preparation methods for spherical silver powders with rough surfaces to obtain spherical silver powders with high surface roughness and good monodispersity. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, propose a spherical silver powder with a rough surface structure, and a preparation method and application thereof, so as to solve the technical problem in the prior art that it is difficult to achieve both surface roughness and monodispersity of spherical silver powder.

[0006] In a first aspect, the present invention provides a method for preparing spherical silver powder having a rough surface structure, comprising the following steps:

[0007] A silver nitrate solution, a reducing agent solution and a dispersant solution are prepared respectively, wherein the reducing agent solution contains an organic doping auxiliary prepared by mixing polyol, polyoxyethylene ether, salt and alkali;

[0008] The silver nitrate solution and the reducing agent solution are simultaneously added dropwise to the dispersant solution, and after the addition is completed, the mixture is stirred for reaction to obtain a reaction solution;

[0009] The reaction solution was settled, the supernatant was poured out, and then anhydrous ethanol was added for dispersion. After the dispersion was completed, solid-liquid separation, washing, and drying were performed to obtain spherical silver powder with a rough surface structure.

[0010] In a second aspect, the present invention provides a spherical silver powder having a rough surface structure, wherein the spherical silver powder having a rough surface structure is obtained by the preparation method of the spherical silver powder having a rough surface structure provided by the first aspect of the present invention.

[0011] In a third aspect, the present invention provides the use of the spherical silver powder having a rough surface structure in preparing a front slurry for solar photovoltaic cells.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] This invention uses silver nitrate as the silver source and successfully produces monodisperse silver powder with a roughened surface structure based on spherical silver powder. The individual silver powder particles are quasi-spherical in shape and exhibit a roughened surface. Laser particle size analysis reveals a D50 value of 1.3-2.0 μm. This silver powder is primarily used in solar photovoltaic cell front-side slurries and exhibits excellent electrical performance and linearity. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a 5000x scanning electron microscope image of the silver powder prepared in Example 1 of the present invention;

[0015] Figure 2 This is a scanning electron microscope image at 8000 times magnification of the silver powder prepared in Example 1 of the present invention;

[0016] Figure 3 This is a 10,000x scanning electron microscope image of the silver powder prepared in Example 1 of the present invention;

[0017] Figure 4 This is a 5000x scanning electron microscope image of the silver powder prepared in Example 2 of the present invention;

[0018] Figure 5 This is a scanning electron microscope image at 8000 times magnification of the silver powder prepared in Example 2 of the present invention;

[0019] Figure 6 This is a 5000x scanning electron microscope image of the silver powder prepared in Example 3 of the present invention;

[0020] Figure 7 This is a scanning electron microscope image at 8000 times magnification of the silver powder prepared in Example 3 of the present invention;

[0021] Figure 8This is a 5000x scanning electron microscope image of the silver powder prepared in Example 4 of the present invention;

[0022] Figure 9 This is a scanning electron microscope image at 8000 times magnification of the silver powder prepared in Example 4 of the present invention;

[0023] Figure 10 This is a 5000x scanning electron microscope image of the silver powder prepared in Comparative Example 1 of the present invention;

[0024] Figure 11 This is a scanning electron microscope image at 8000 times magnification of the silver powder prepared in Comparative Example 1 of the present invention;

[0025] Figure 12 This is a 10,000x scanning electron microscope image of the silver powder prepared in Comparative Example 1 of the present invention;

[0026] Figure 13 This is a 5000x scanning electron microscope image of the silver powder prepared in Comparative Example 2 of the present invention;

[0027] Figure 14 This is a scanning electron microscope image at 8000 times magnification of the silver powder prepared in Comparative Example 2 of the present invention;

[0028] Figure 15 This is a 10,000x scanning electron microscope image of the silver powder prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] In a first aspect, the present invention provides a method for preparing spherical silver powder having a rough surface structure, comprising the following steps:

[0031] S1. Prepare a silver nitrate solution, a reducing agent solution and a dispersant solution respectively, wherein the reducing agent solution contains an organic doping auxiliary prepared by mixing a polyol, polyoxyethylene ether, a salt and an alkali;

[0032] S2, adding the silver nitrate solution and the reducing agent solution dropwise to the dispersant solution simultaneously, stirring and reacting after the addition is completed to obtain a reaction solution;

[0033] S3. The reaction solution is allowed to settle, the supernatant is poured out, and then anhydrous ethanol is added for dispersion. After the dispersion is completed, solid-liquid separation, washing, and drying are performed to obtain spherical silver powder with a rough surface structure.

[0034] The organic doping agent of the present invention comprises a polyol as the main component, a salt and a polyoxyethylene ether as the complexing agent, and a base to adjust the pH of the organic doping agent. By adding the organic doping agent to a reducing agent solution, the present invention effectively produces a roughened surface, resulting in monodisperse, quasi-spherical silver powder with a roughened surface structure.

[0035] In this embodiment, the preparation process of the silver nitrate solution includes: dissolving silver nitrate in water to obtain the silver nitrate solution.

[0036] In this embodiment, the concentration of silver nitrate in the silver nitrate solution is 0.1-0.5 g / mL, including but not limited to 0.1 g / mL, 0.2 g / mL, 0.3 g / mL, 0.4 g / mL, 0.5 g / mL, etc.

[0037] In this embodiment, the reducing agent solution is prepared by dissolving the reducing agent and the organic doping auxiliary agent in water to obtain the reducing agent solution.

[0038] In this embodiment, in the reducing agent solution, the reducing agent is at least one of ascorbic acid, glucose, formaldehyde, triethanolamine, and hydrazine hydrate.

[0039] In this embodiment, the theoretical stoichiometric ratio of silver nitrate to the reducing agent is 1:(1-1.2).

[0040] In this embodiment, the concentration of the reducing agent in the reducing agent solution is 0.1-0.3 g / mL, including but not limited to 0.1 g / mL, 0.15 g / mL, 0.2 g / mL, 0.25 g / mL, 0.3 g / mL, etc.

[0041] In this embodiment, the mass of the organic doping auxiliary agent is 2-5% of the silver nitrate, including but not limited to 2%, 3%, 4%, 5%, etc.

[0042] In this embodiment, the concentration of the organic doping aid in the reducing agent solution is 0.005-0.01 g / mL, including but not limited to 0.005 g / mL, 0.006 g / mL, 0.007 g / mL, 0.008 g / mL, 0.009 g / mL, 0.01 g / mL, etc.

[0043] In this embodiment, the polyol is at least one of ethylene glycol, propylene glycol, and glycerol.

[0044] In this embodiment, the polyoxyethylene ether is at least one of alkylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, lauric acid polyoxyethylene ether, and castor oil polyoxyethylene ether.

[0045] In this embodiment, the salt is at least one of sodium carbonate, sodium citrate, and ammonium acetate.

[0046] In this embodiment, the base is at least one of sodium hydroxide or ammonia water.

[0047] In this embodiment, the organic doping auxiliary agent is composed of the following raw materials in percentage by mass: 60% to 70% of polyol, 5% to 10% of polyoxyethylene ether, 20% to 30% of salt, and 5% to 10% of alkali.

[0048] In this embodiment, the preparation process of the dispersant solution includes: dissolving the dispersant and the initiator in water to obtain the dispersant solution.

[0049] In this embodiment, in the dispersant solution, the dispersant is at least one of polyethylene glycol, polyvinyl pyrrolidone, gelatin, and gum arabic.

[0050] In some embodiments of the present invention, the dispersant is PEG-1000 or polyvinyl pyrrolidone K30.

[0051] In this embodiment, the amount of the dispersant used is 10-20% of the mass of the silver powder obtained by the reaction, including but not limited to 10%, 12%, 14%, 16%, 18%, 20%, etc.

[0052] In this embodiment, in the dispersant solution, the concentration of the dispersant is 0.01-0.03 g / mL, including but not limited to 0.01 g / mL, 0.015 g / mL, 0.02 g / mL, 0.025 g / mL, 0.03 g / mL, etc.

[0053] In this embodiment, the initiator in the dispersant solution is ammonia water. In the present invention, ammonia water is added to the dispersant solution as an initiator to induce nucleation.

[0054] Preferably, the mass fraction of ammonia water is 10-30%, including but not limited to 10%, 15%, 20%, 25%, 30%, etc.; the dosage ratio of ammonia water to silver nitrate is (0.001-0.005) mL:1 g, including but not limited to 0.001 mL:1 g, 0.002 mL:1 g, 0.003 mL:1 g, 0.004 mL:1 g, 0.005 mL:1 g, etc.

[0055] In this embodiment, during the dropwise addition process and the stirring reaction process, the stirring rate is 400-600 rpm.

[0056] In this embodiment, the dropwise addition time of the silver nitrate solution and the reducing agent solution is 0.5 to 2 minutes, including but not limited to 0.5 minutes, 0.8 minutes, 1 minute, 1.2 minutes, 1.5 minutes, 1.8 minutes, 2 minutes, etc.

[0057] In some specific embodiments of the present invention, the dropping rate of the silver nitrate solution and the reducing agent solution is 600-700 mL / min.

[0058] In this embodiment, the stirring reaction time is 2-10 minutes, including but not limited to 2 minutes, 4 minutes, 6 minutes, 8 minutes, 10 minutes, etc.

[0059] In this embodiment, before the reaction liquid is allowed to settle, the process further includes: adding a coating agent solution into the reaction liquid and continuing to stir.

[0060] Preferably, the preparation process of the coating agent solution includes: dissolving the coating agent in anhydrous ethanol to obtain the coating agent solution.

[0061] Preferably, the coating agent is at least one of oleic acid, lauric acid, stearic acid, and palmitic acid.

[0062] Preferably, the amount of the coating agent is 0.1-1% of the mass of the silver powder obtained by the reaction, including but not limited to 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, etc.

[0063] Preferably, in the coating agent solution, the concentration of the coating agent is 0.01-0.1 g / mL, including but not limited to 0.01 g / mL, 0.02 g / mL, 0.04 g / mL, 0.06 g / mL, 0.08 g / mL, 0.1 g / mL, etc.

[0064] Preferably, the stirring time is 2-10 min, including but not limited to 2 min, 4 min, 6 min, 8 min, 10 min, etc.

[0065] In the present invention, the above reactions are all carried out at normal temperature and pressure.

[0066] In this embodiment, during the dispersion process, the stirring rate is 800-1000 rpm, and the stirring time is 10-30 min.

[0067] In this embodiment, the washing process includes: washing the silver powder with deionized water and anhydrous ethanol respectively until the conductivity of the filtrate is less than 20 μS / m.

[0068] In this embodiment, the drying temperature is 40-80° C., and the drying time is 6-24 hours.

[0069] In a second aspect, the present invention provides a spherical silver powder having a rough surface structure, wherein the spherical silver powder having a rough surface structure is obtained by the preparation method of the spherical silver powder having a rough surface structure provided by the first aspect of the present invention.

[0070] In a third aspect, the present invention provides the use of the spherical silver powder having a rough surface structure in preparing a front slurry for solar photovoltaic cells.

[0071] Example 1

[0072] (1) Preparation of organic doping additives

[0073] Weigh 70g of glycerol into a beaker and stir with a magnetic rotor at 500rpm. Add 5g of sodium hydroxide to adjust the pH. Once completely dissolved, add 5g of nonylphenol polyoxyethylene ether and stir thoroughly. Finally, add 20g of sodium carbonate and stir for 30 minutes to fully dissolve.

[0074] (2) Liquid preparation

[0075] Preparation of Solution A: Add 160 g of silver nitrate to a beaker, add 600 mL of deionized water and stir to dissolve to obtain Solution A;

[0076] Preparation of Solution B: 86.4 g of ascorbic acid was added to a beaker, and 600 mL of deionized water was added and stirred to dissolve. After complete dissolution, 5 g of an organic doping agent was added to the solution to obtain Solution B.

[0077] Preparation of Solution C: Take 16g of polyvinyl pyrrolidone (K30) and add it to a beaker. Add 880mL of deionized water and stir to dissolve. After it is completely dissolved, add 0.5mL of ammonia water (mass fraction 25-28%, the same below) and stir evenly to obtain Solution C.

[0078] Preparation of solution D: Take 0.5 g of oleic acid and add it into a beaker. Add 10 mL of anhydrous ethanol and stir to dissolve to obtain solution D.

[0079] (3) Preparation of silver powder

[0080] a. Transfer solution C to the reactor, start mechanical stirring, and control the stirring rate to 500 rpm;

[0081] b. The flow rates of solution A and solution B were adjusted to 600-700 mL / min and added to the reactor simultaneously, and the mechanical stirring rate of the reactor was controlled to 500 rpm;

[0082] c. After the addition is completed, stir for 5 minutes, add solution D, continue stirring for 5 minutes, and the reaction is completed;

[0083] d. Allow the reaction suspension to settle, pour off the supernatant, then add anhydrous ethanol to the reactor and stir at 1000 rpm for 20 minutes. After stirring, perform solid-liquid separation and wash the silver powder with deionized water and anhydrous ethanol until the filtrate conductivity is <20 μS / m. Dry the mixture in a 60°C air drying oven for 12 hours.

[0084] Example 2

[0085] (1) Preparation of organic doping additives

[0086] Weigh 70g of ethylene glycol into a beaker and stir magnetically with a magnetic rotor at 500rpm. Add 5g of sodium hydroxide to adjust the pH. Once completely dissolved, add 5g of nonylphenol polyoxyethylene ether and stir thoroughly. Finally, add 20g of sodium carbonate and stir for 30 minutes to fully dissolve.

[0087] (2) Liquid preparation

[0088] Preparation of Solution A: Add 160 g of silver nitrate to a beaker, add 600 mL of deionized water and stir to dissolve to obtain Solution A;

[0089] Preparation of Solution B: 86.4 g of ascorbic acid was added to a beaker, and 600 mL of deionized water was added and stirred to dissolve. After complete dissolution, 5 g of an organic doping agent was added to the solution to obtain Solution B.

[0090] Preparation of Solution C: Take 16g of polyvinyl pyrrolidone (K30) and add it to a beaker. Add 880mL of deionized water and stir to dissolve. After it is completely dissolved, add 0.5mL of ammonia water and stir evenly to obtain Solution C.

[0091] Preparation of solution D: Take 0.5 g of oleic acid and add it into a beaker. Add 10 mL of anhydrous ethanol and stir to dissolve to obtain solution D.

[0092] (3) Preparation of silver powder

[0093] a. Transfer solution C to the reactor, start mechanical stirring, and control the stirring rate to 500 rpm;

[0094] b. The flow rates of solution A and solution B were adjusted to 600-700 mL / min and added to the reactor simultaneously, and the mechanical stirring rate of the reactor was controlled to 500 rpm;

[0095] c. After the addition is completed, stir for 5 minutes, add solution D, continue stirring for 5 minutes, and the reaction is completed;

[0096] d. Allow the reaction suspension to settle, pour off the supernatant, then add anhydrous ethanol to the reactor and stir at 1000 rpm for 20 minutes. After stirring, perform solid-liquid separation and wash the silver powder with deionized water and anhydrous ethanol until the filtrate conductivity is <20 μS / m. Dry the mixture in a 60°C air drying oven for 12 hours.

[0097] Example 3

[0098] (1) Preparation of organic doping additives

[0099] Weigh 65g of glycerol into a beaker and stir with a magnetic rotor at 500rpm. Add 5g of sodium hydroxide to adjust the pH. Once completely dissolved, add 5g of nonylphenol polyoxyethylene ether and stir thoroughly. Finally, add 25g of sodium citrate and stir for 30 minutes to fully dissolve.

[0100] (2) Liquid preparation

[0101] Preparation of Solution A: Add 160 g of silver nitrate to a beaker, add 600 mL of deionized water and stir to dissolve to obtain Solution A;

[0102] Preparation of Solution B: 86.4 g of ascorbic acid was added to a beaker, and 600 mL of deionized water was added and stirred to dissolve. After complete dissolution, 5 g of an organic doping agent was added to the solution to obtain Solution B.

[0103] Preparation of Solution C: Take 16g of polyvinyl pyrrolidone (K30) and add it to a beaker. Add 880mL of deionized water and stir to dissolve. After it is completely dissolved, add 0.5mL of ammonia water and stir evenly to obtain Solution C.

[0104] Preparation of solution D: Take 0.5 g of oleic acid and add it into a beaker. Add 10 mL of anhydrous ethanol and stir to dissolve to obtain solution D.

[0105] (3) Preparation of silver powder

[0106] a. Transfer solution C to the reactor, start mechanical stirring, and control the stirring rate to 500 rpm;

[0107] b. The flow rates of solution A and solution B were adjusted to 600-700 mL / min and added to the reactor simultaneously, and the mechanical stirring rate of the reactor was controlled to 500 rpm;

[0108] c. After the addition is completed, stir for 5 minutes, add solution D, continue stirring for 5 minutes, and the reaction is completed;

[0109] d. Allow the reaction suspension to settle, pour off the supernatant, then add anhydrous ethanol to the reactor and stir at 1000 rpm for 20 minutes. After stirring, perform solid-liquid separation and wash the silver powder with deionized water and anhydrous ethanol until the filtrate conductivity is <20 μS / m. Dry the mixture in a 60°C air drying oven for 12 hours.

[0110] Example 4

[0111] (1) Preparation of organic doping additives

[0112] Weigh 65g of glycerol into a beaker and stir with a magnetic rotor at 500rpm. Add 5g of sodium hydroxide to adjust the pH. Once completely dissolved, add 5g of nonylphenol polyoxyethylene ether and stir thoroughly. Finally, add 25g of ammonium acetate and stir for 30 minutes to fully dissolve.

[0113] (2) Liquid preparation

[0114] Preparation of Solution A: Add 160 g of silver nitrate to a beaker, add 600 mL of deionized water and stir to dissolve to obtain Solution A;

[0115] Preparation of Solution B: 86.4 g of ascorbic acid was added to a beaker, and 600 mL of deionized water was added and stirred to dissolve. After complete dissolution, 5 g of an organic doping agent was added to the solution to obtain Solution B.

[0116] Preparation of Solution C: Take 16g of polyvinyl pyrrolidone (K30) and add it to a beaker. Add 880mL of deionized water and stir to dissolve. After it is completely dissolved, add 0.5mL of ammonia water and stir evenly to obtain Solution C.

[0117] Preparation of solution D: Take 0.5 g of oleic acid and add it into a beaker. Add 10 mL of anhydrous ethanol and stir to dissolve to obtain solution D.

[0118] (3) Preparation of silver powder

[0119] a. Transfer solution C to the reactor, start mechanical stirring, and control the stirring rate to 500 rpm;

[0120] b. The flow rates of solution A and solution B were adjusted to 600-700 mL / min and added to the reactor simultaneously, and the mechanical stirring rate of the reactor was controlled to 500 rpm;

[0121] c. After the addition is completed, stir for 5 minutes, add solution D, continue stirring for 5 minutes, and the reaction is completed;

[0122] d. Allow the reaction suspension to settle, pour off the supernatant, then add anhydrous ethanol to the reactor and stir at 1000 rpm for 20 minutes. After stirring, perform solid-liquid separation and wash the silver powder with deionized water and anhydrous ethanol until the filtrate conductivity is <20 μS / m. Dry the mixture in a 60°C air drying oven for 12 hours.

[0123] Comparative Example 1

[0124] (1) Liquid preparation

[0125] Preparation of Solution A: Add 160 g of silver nitrate to a beaker, add 600 mL of deionized water and stir to dissolve to obtain Solution A;

[0126] Preparation of Solution B: Take 86.4 g of ascorbic acid and add it to a beaker. Add 600 mL of deionized water and stir to dissolve to obtain Solution B.

[0127] Preparation of Solution C: Take 16g of polyvinyl pyrrolidone (K30) and add it to a beaker. Add 880mL of deionized water and stir to dissolve. After it is completely dissolved, add 0.5mL of ammonia water and stir evenly to obtain Solution C.

[0128] Preparation of solution D: Take 0.5 g of oleic acid and add it into a beaker. Add 10 mL of anhydrous ethanol and stir to dissolve to obtain solution D.

[0129] (2) Preparation of silver powder

[0130] a. Transfer solution C to the reactor, start mechanical stirring, and control the stirring rate to 500 rpm;

[0131] b. The pH value of solution B was adjusted to 5.5 (pH consistent with Example 1) using a 10 mol / L sodium hydroxide solution, and then the flow rates of solution A and solution B were adjusted to 600-700 mL / min and added to the reactor simultaneously. The mechanical stirring rate of the reactor was controlled to 500 rpm.

[0132] c. After the addition is completed, stir for 5 minutes, add solution D, continue stirring for 5 minutes, and the reaction is completed;

[0133] d. Allow the reaction suspension to settle, pour off the supernatant, then add anhydrous ethanol to the reactor and stir at 1000 rpm for 20 minutes. After stirring, perform solid-liquid separation and wash the silver powder with deionized water and anhydrous ethanol until the filtrate conductivity is <20 μS / m. Dry the mixture in a 60°C air drying oven for 12 hours.

[0134] Comparative Example 2

[0135] All the liquid preparation and silver powder preparation conditions are the same as those in Example 1, except that the amount of organic doping auxiliary agent is reduced to 2.5 g. The specific steps are as follows:

[0136] (1) Preparation of organic doping additives

[0137] Weigh 70g of glycerol into a beaker and stir with a magnetic rotor at 500rpm. Add 5g of sodium hydroxide to adjust the pH. Once completely dissolved, add 5g of nonylphenol polyoxyethylene ether and stir thoroughly. Finally, add 20g of sodium carbonate and stir for 30 minutes to fully dissolve.

[0138] (2) Liquid preparation

[0139] Preparation of Solution A: Add 160 g of silver nitrate to a beaker, add 600 mL of deionized water and stir to dissolve to obtain Solution A;

[0140] Preparation of Solution B: 86.4 g of ascorbic acid was added to a beaker, and 600 mL of deionized water was added and stirred to dissolve. After complete dissolution, 2.5 g of an organic doping agent was added to the solution to obtain Solution B.

[0141] Preparation of Solution C: Take 16g of polyvinyl pyrrolidone (K30) and add it to a beaker. Add 880mL of deionized water and stir to dissolve. After it is completely dissolved, add 0.5mL of ammonia water and stir evenly to obtain Solution C.

[0142] Preparation of solution D: Take 0.5 g of oleic acid and add it into a beaker. Add 10 mL of anhydrous ethanol and stir to dissolve to obtain solution D.

[0143] (3) Preparation of silver powder

[0144] a. Transfer solution C to the reactor, start mechanical stirring, and control the stirring rate to 500 rpm;

[0145] b. The flow rates of solution A and solution B were adjusted to 600-700 mL / min and added to the reactor simultaneously, and the mechanical stirring rate of the reactor was controlled to 500 rpm;

[0146] c. After the addition is completed, stir for 5 minutes, add solution D, continue stirring for 5 minutes, and the reaction is completed;

[0147] d. Allow the reaction suspension to settle, pour off the supernatant, then add anhydrous ethanol to the reactor and stir at 1000 rpm for 20 minutes. After stirring, perform solid-liquid separation and wash the silver powder with deionized water and anhydrous ethanol until the filtrate conductivity is <20 μS / m. Dry the mixture in a 60°C air drying oven for 12 hours.

[0148] Performance testing

[0149] The performance of the silver powder prepared in the above examples and comparative examples was tested, and the test results are shown in Tables 1 and Figures 1 to 15 .

[0150] Particle size: Particle size distribution analysis was performed using a Malvern 3000 laser particle size analyzer. Sample pretreatment involved ultrasonic dispersion with alcohol for 6 min, using deionized water as the dispersion medium.

[0151] Burning loss: The burning loss test was carried out by muffle furnace calcination. The silver powder was calcined at 538℃ and the calcination time was 0.5h.

[0152] Loose / tapped density: The bulk and tapped density tests were performed using a Better BT-310 tap density tester with a sample size of 25 cm 3 , vibration 3000 times, vibration frequency 300 times / min;

[0153] Specific surface area: The specific surface area of ​​silver powder was tested using a Bester 3H-2000 specific surface analyzer;

[0154] Scanning electron microscope (SEM) was used to characterize the morphology of the silver powder.

[0155] Table 1

[0156]

[0157] Through Table 1 and Figure 1-15 It can be seen that after adding the organic doping agent during the reaction process, monodisperse spherical silver powder can be obtained.

[0158] pass Figure 1-15 It can be seen that after adding the organic doping agent during the reaction process, the surface of the silver powder becomes obviously roughened, and the degree and type of surface roughening are inconsistent when different materials and proportions are used.

[0159] Compared with Example 1, in Comparative Example 1, no organic doping agent was added, and the surface of the prepared silver powder was obviously smooth and had an irregular polyhedral spherical shape.

[0160] Compared with Example 1, in Comparative Example 2, after the amount of the organic doping auxiliary agent was reduced, the surface roughness was reduced and the uniformity of the system was reduced, indicating that too low an amount of the organic doping auxiliary agent was not conducive to roughening the surface of the silver powder.

[0161] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing spherical silver powder having a rough surface structure, characterized in that: The following steps are involved: A silver nitrate solution, a reducing agent solution and a dispersant solution are prepared respectively, wherein the reducing agent solution contains an organic doping auxiliary prepared by mixing polyol, polyoxyethylene ether, salt and alkali; Adding the silver nitrate solution and the reducing agent solution dropwise to the dispersant solution simultaneously, stirring and reacting after the addition is completed to obtain a reaction solution; The reaction solution is allowed to settle, the supernatant is poured out, and then anhydrous ethanol is added for dispersion. After the dispersion is completed, solid-liquid separation, washing, and drying are performed to obtain spherical silver powder with a rough surface structure; wherein, The reducing agent is at least one of ascorbic acid, glucose, formaldehyde, triethanolamine, and hydrazine hydrate; The mass of the organic doping auxiliary agent is 2-5% of silver nitrate; The salt is at least one of sodium carbonate, sodium citrate, and ammonium acetate; The organic doping auxiliary agent is composed of the following raw materials in percentage by mass: 60% to 70% of polyol, 5% to 10% of polyoxyethylene ether, 20% to 30% of salt, and 5% to 10% of alkali.

2. The method for preparing the spherical silver powder having a rough surface structure according to claim 1, characterized in that: The preparation process of the silver nitrate solution includes: dissolving silver nitrate in water to obtain the silver nitrate solution; wherein, In the silver nitrate solution, the concentration of silver nitrate is 0.1-0.5 g / mL.

3. The method for preparing the spherical silver powder having a rough surface structure according to claim 1, characterized in that: The preparation process of the reducing agent solution includes: dissolving the reducing agent and the organic doping auxiliary agent in water to obtain the reducing agent solution; wherein, The theoretical stoichiometric ratio of the silver nitrate to the reducing agent is 1:(1-1.2); and / or, In the reducing agent solution, the concentration of the reducing agent is 0.1-0.3 g / mL; and / or, In the reducing agent solution, the concentration of the organic doping auxiliary agent is 0.005-0.01 g / mL.

4. The method for preparing the spherical silver powder having a rough surface structure according to claim 1, characterized in that: The polyol is at least one of ethylene glycol, propylene glycol and glycerol; and / or, The polyoxyethylene ether is at least one of alkylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, lauric acid polyoxyethylene ether, and castor oil polyoxyethylene ether; and / or, The alkali is at least one of sodium hydroxide and ammonia water.

5. The method for preparing the spherical silver powder having a rough surface structure according to claim 1, characterized in that: The preparation process of the dispersant solution includes: dissolving the dispersant and the initiator in water to obtain the dispersant solution; wherein, The dispersant is at least one of polyethylene glycol, polyvinyl pyrrolidone, gelatin, and gum arabic; and / or, The amount of the dispersant is 10-20% of the mass of the silver powder obtained by the reaction; and / or, The initiator is aqueous ammonia; and / or, In the dispersant solution, the concentration of the dispersant is 0.01-0.03 g / mL; and / or, In the process of preparing the dispersant solution, the mass fraction of the initiator used is 10~30%, and the amount ratio of the initiator to silver nitrate is (0.001~0.005)mL:1g.

6. The method for preparing spherical silver powder having a rough surface structure according to claim 1, characterized in that: During the dropwise addition process and the stirring reaction process, the stirring rate is 400-600 rpm; and / or, The silver nitrate solution and the reducing agent solution are both added dropwise for 0.5 to 2 minutes; and / or, The stirring reaction time is 2-10 minutes.

7. The method for preparing spherical silver powder having a rough surface structure according to claim 1, characterized in that: Before the reaction solution is settled, the method further comprises: dissolving the coating agent in anhydrous ethanol to obtain a coating agent solution; Add the coating agent solution to the reaction solution and continue stirring; wherein, The coating agent is at least one of oleic acid, lauric acid, stearic acid, and palmitic acid; and / or, The amount of the coating agent is 0.1-1% of the mass of the silver powder obtained by the reaction; and / or, In the coating agent solution, the concentration of the coating agent is 0.01-0.1 g / mL; and / or, The stirring time is 2-10 minutes.

8. The method for preparing spherical silver powder having a rough surface structure according to claim 1, characterized in that: During the dispersion process, the stirring rate is 800-1000 rpm and the stirring time is 10-30 min.

9. A spherical silver powder having a rough surface structure, characterized in that: The spherical silver powder having a rough surface structure is obtained by the preparation method of the spherical silver powder having a rough surface structure according to any one of claims 1 to 8.

10. Use of the spherical silver powder having a rough surface structure as claimed in claim 9 in preparing a front slurry for solar photovoltaic cells.

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