High-surface-activity micro-nano spherical silver powder and preparation method and application thereof

Abstract

The invention discloses high-surface-activity micro-nano spherical silver powder and a preparation method and application thereof. The preparation method comprises the following steps: mixing a dispersing agent with a silver-ammonia solution to obtain a mixed solution; under the condition of continuous stirring, a reducing agent is added into the mixed solution for a first reaction, then a surface treating agent is added for a second reaction, and a silver powder initial product is obtained; mixing the silver powder primary product, a modified dispersing agent and a coating agent, and modifying the silver powder primary product to obtain the high-surface-activity micro-nano spherical silver powder, the particle size distribution D50 of the high-surface-activity micro-nano spherical silver powder is 0.6-1.0 mu m, and the specific surface area is not smaller than 1.7 m < 2 > / g. The preparation method provided by the invention is simple in technological process, simple and convenient to charge, rapid in reaction and convenient for large-scale stable production of the high-surface-activity micro-nano spherical silver powder.

Description

Technical Field

[0001] The invention belongs to the technical field of metal powder material preparation, and specifically relates to a high-surface-activity micro-nano spherical silver powder and a preparation method and application thereof. Background Art

[0002] Conductive silver paste for photovoltaics is a key material used in the manufacture of photovoltaic cells. It is mainly composed of silver powder, glass powder, organic carrier and other components. Silver powder is the main part of silver paste, and its performance will have a great impact on the silver paste. With the continuous development of the photovoltaic industry, the performance of photovoltaic cells needs to be better, and as the most important component, the industry has also put forward higher requirements on the performance of silver powder.

[0003] At present, the most commonly used method for preparing silver powder is the liquid phase reduction method, in which silver powder is obtained by reacting a soluble silver salt with a reducing agent. In order to obtain silver powder with fine particle size and narrow particle size distribution, the prior art usually uses a metering pump or a peristaltic pump to control the feeding. The feeding time is relatively long, or the pH value of the reaction solution needs to be adjusted. The steps are relatively cumbersome and not conducive to large-scale preparation. In addition, the silver powder prepared by the prior art has insufficient surface activity. Researchers usually increase the specific surface area to increase the surface activity of the silver powder. For example, patent CN117680693A discloses a method for preparing irregular micro-nano silver powder with high surface activity. The silver powder prepared by this method has a narrow particle size distribution, a large specific surface area and a high tap density, but its specific surface area does not exceed 1.6m 2 / g, the surface activity needs to be further improved, and its surface is irregular, resulting in poor fluidity of the silver powder and inability to distribute it evenly during printing. Summary of the invention

[0004] The main purpose of the present invention is to provide a micro-nano spherical silver powder with high surface activity and a preparation method and application thereof, so as to overcome the deficiencies in the prior art.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0006] One aspect of the present invention provides a method for preparing micro-nano spherical silver powder with high surface activity, comprising:

[0007] Mixing the dispersant with the silver ammonia solution to obtain a mixed solution;

[0008] Under the condition of continuous stirring, a reducing agent is added to the mixed solution to carry out a first reaction, and then a surface treatment agent is added to carry out a second reaction to obtain a primary product of silver powder;

[0009] The silver powder primary product, the modified dispersant and the coating agent are mixed to modify the silver powder primary product to obtain micro-nano spherical silver powder with high surface activity;

[0010] The particle size distribution D50 of the high surface activity micro-nano spherical silver powder is 0.6-1.0 μm, and the specific surface area is not less than 1.7 m 2 / g.

[0011] Another aspect of the present invention provides a high-surface-activity micro-nano spherical silver powder prepared by the above-mentioned preparation method, wherein the particle size distribution D50 of the high-surface-activity micro-nano spherical silver powder is 0.6-1.0 μm, and the specific surface area is not less than 1.7 m 2 / g.

[0012] Another aspect of the present invention also provides the use of the aforementioned high-surface-activity micro-nano spherical silver powder in solar cells or electronic appliances.

[0013] Compared with the prior art, the technical solution of the present invention has at least the following advantages:

[0014] 1) The preparation method provided by the present invention comprises adding ammonia water to prepare a silver ammonia solution, + Convert to [Ag(NH3)2] + , thereby regulating the reaction process, which is conducive to obtaining silver powder with a more uniform particle size distribution;

[0015] 2) The preparation method provided by the present invention has a simple process, is easy to add materials, has a rapid reaction, and is convenient for the stable mass production of high-surface-active micro-nano spherical silver powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a scanning electron microscope image of the high surface activity micro-nano spherical silver powder prepared in Example 1 of the present invention;

[0018] Figure 2 This is a scanning electron microscope image of the high surface activity micro-nano spherical silver powder prepared in Example 2 of the present invention;

[0019] Figure 3 This is a scanning electron microscope image of the high surface activity micro-nano spherical silver powder prepared in Example 3 of the present invention;

[0020] Figure 4 This is a scanning electron microscope image of the high surface activity micro-nano spherical silver powder prepared in Example 4 of the present invention;

[0021] Figure 5 This is a scanning electron microscope image of the silver powder prepared in Comparative Example 1 of the present invention;

[0022] Figure 6 This is a scanning electron microscope image of the silver powder prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be more fully understood by reading the following specific embodiments. However, it should be understood that the specific embodiments disclosed below are only exemplary of the present invention, and the present invention can be embodied in various forms. Therefore, the specific functional details disclosed herein should not be interpreted as limiting, but only as the basis for the claims and as a representative basis for teaching those skilled in the art to adopt the present invention in different ways in any appropriate detailed embodiment.

[0024] As one aspect of the technical solution of the present invention, a method for preparing a high-surface-activity micro-nano spherical silver powder involves:

[0025] Mixing the dispersant with the silver ammonia solution to obtain a mixed solution;

[0026] Under the condition of continuous stirring, a reducing agent is added to the mixed solution to carry out a first reaction, and then a surface treatment agent is added to carry out a second reaction to obtain a primary product of silver powder;

[0027] The silver powder primary product, the modified dispersant and the coating agent are mixed to modify the silver powder primary product to obtain micro-nano spherical silver powder with high surface activity;

[0028] The particle size distribution D50 of the high surface activity micro-nano spherical silver powder is 0.6-1.0 μm, and the specific surface area is not less than 1.7 m 2 / g.

[0029] In some embodiments, the preparation method comprises: adding a dispersant solution to a silver ammonia solution under stirring and mixing the mixture evenly to obtain the mixed solution.

[0030] In some preferred embodiments, the concentration of the dispersant solution is 3-6 wt %.

[0031] In some preferred embodiments, the mass fraction of the silver ammonia solution is 16-23 wt %.

[0032] In some embodiments, the mass of the dispersant in the mixed solution is 5%-50% of the mass of the silver element.

[0033] In some embodiments, the concentration of the dispersant in the mixed solution is 1.3-2.3 wt %.

[0034] In some embodiments, the dispersant includes, but is not limited to, any one or a combination of two or more of Tween, polyvinyl pyrrolidone (PVP), polyethylene glycol, gelatin, polyvinyl alcohol, gum arabic, and sodium citrate.

[0035] In some embodiments, the silver ammonia solution is obtained by mixing a silver-containing oxidant solution with aqueous ammonia.

[0036] In some preferred embodiments, the concentration of the silver-containing oxidant solution is 20-40 wt %.

[0037] In some preferred embodiments, the mass ratio of the silver-containing oxidant solution to aqueous ammonia is 2-6:1.

[0038] In some preferred embodiments, the silver-containing oxidizing agent comprises silver nitrate.

[0039] In some embodiments, the preparation method comprises: adding a reducing agent solution to the mixed solution under continuous stirring to carry out the first reaction.

[0040] In some preferred embodiments, the stirring speed is 200-600 r / min.

[0041] In some preferred embodiments, the temperature of the first reaction is room temperature, and the time is 5-15 minutes.

[0042] In some preferred embodiments, the molar ratio of the reducing agent in the reducing agent solution to the silver element in the mixed solution is (0.5-2):1.

[0043] In some preferred embodiments, the concentration of the reducing agent solution is 16-19 wt %.

[0044] In some preferred embodiments, the reducing agent includes but is not limited to any one or a combination of two or more of hydrazine hydrate, glucose, ascorbic acid, sodium citrate, sodium hypophosphite, sodium borohydride, hydroquinone, formaldehyde, and acetaldehyde.

[0045] In some preferred embodiments, the time for the reducing agent solution to completely enter the mixed solution is 1-30 seconds.

[0046] In some embodiments, the mass of the surface treatment agent is 1%-3% of the mass of the silver element in the mixed solution.

[0047] In some embodiments, the surface treatment agent includes, but is not limited to, any one or a combination of two or more of lauric acid, stearic acid, sodium dodecylbenzene sulfonate, oleic acid, palmitic acid, and benzotriazole. The purpose of adding the surface treatment agent is to improve the dispersibility of the silver powder and prevent agglomeration.

[0048] In some embodiments, the temperature of the second reaction is room temperature, and the time is 5-15 minutes.

[0049] In some embodiments, the preparation method includes: mixing the initial silver powder product, the modified dispersant and the coating agent, performing a stirring and dispersing treatment, modifying the initial silver powder product, and obtaining the high surface activity micro-nano spherical silver powder.

[0050] In some preferred embodiments, the mass ratio of the primary silver powder product, the modified dispersant and the coating agent is 1:(0.7-2):(0.01-0.03).

[0051] In some preferred embodiments, the modified dispersant includes but is not limited to any one of water and ethanol or a combination of both.

[0052] In some preferred embodiments, the coating agent includes, but is not limited to, any one or a combination of two or more of lauric acid, stearic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecylhydroxystearic acid, sodium dodecylbenzenesulfonate, and oleic acid. Adding a coating agent can further improve the dispersibility of the silver powder and reduce agglomeration.

[0053] In some embodiments, the preparation method includes: washing the initial silver powder product until the conductivity is below 20 μS / cm, and then mixing it with the modified dispersant and coating agent to modify the initial silver powder product.

[0054] In some more specific embodiments, the method for preparing the high surface activity micro-nano spherical silver powder comprises the following steps:

[0055] S1: preparing a silver-containing oxidant solution, a dispersant solution, and a reducing agent solution respectively;

[0056] S2: adding ammonia water to the silver-containing oxidant solution to prepare a silver ammonia solution;

[0057] S3: adding the dispersant solution to the silver ammonia solution under stirring at 200-600 r / min and mixing them evenly to obtain a mixed solution;

[0058] S4: adding the reducing agent solution to the mixed solution under stirring conditions of 200-600 r / min to react, adding the surface treatment agent after reacting for 5-15 minutes, and continuing the reaction for 5-15 minutes; after the reaction is completed, removing the supernatant after the reaction by sedimentation, and the remaining part is the initial product of silver powder;

[0059] S5: The remaining part is washed in the reactor until the conductivity is ≤20μS / cm, and then transferred to a disperser. A modified dispersant and a coating agent are added. After high-speed stirring and dispersion, the suspension containing the silver powder is washed clean, dried, and crushed to obtain high-surface-active micro-nano spherical silver powder.

[0060] As another aspect of the technical solution of the present invention, it relates to a high-surface-activity micro-nano spherical silver powder prepared by the above-mentioned preparation method, wherein the particle size distribution D50 of the high-surface-activity micro-nano spherical silver powder is 0.6-1.0 μm, and the specific surface area is not less than 1.7 m 2 / g.

[0061] As another aspect of the technical solution of the present invention, it involves the application of the aforementioned high-surface-activity micro-nano spherical silver powder in solar cells or electronic appliances.

[0062] In some embodiments, the application includes: using the high surface activity micro-nano spherical silver powder to prepare silver paste for solar cells.

[0063] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The reagents and raw materials used in the following examples are commercially available, and the experimental methods without specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers.

[0064] Example 1

[0065] A method for preparing micro-nano spherical silver powder with high surface activity comprises the following steps:

[0066] Dissolve 240 g of silver nitrate in 845 g of deionized water to obtain a 22 wt % oxidant solution;

[0067] Dissolve 153 g of ascorbic acid in 801 g of deionized water to obtain a 16 wt % reducing agent solution;

[0068] Dissolve 45.6 g of PVP in 1020 g of deionized water to obtain a 4.28 wt % dispersant solution;

[0069] Add 240 ml of 25% ammonia water (the mass ratio of the oxidant solution to the ammonia water is 5:1) to the oxidant solution to obtain a silver ammonia solution with a mass fraction of 18.45%;

[0070] The dispersant solution is added to the silver ammonia solution at a stirring speed of 400 r / min, so that the silver ammonia solution and the dispersant solution are evenly mixed to obtain a base liquid; the mass of the dispersant in the base liquid is 30% of the mass of the silver element, and the mass content of the dispersant in the base liquid is 1.9%;

[0071] Add the reducing agent solution to the base solution within 5 seconds; the molar ratio of the reducing agent in the reducing agent solution to the silver element in the base solution is 1:1;

[0072] After adding the reducing agent solution to the base solution, the reaction is continued for 5 minutes, and then the surface treatment agent lauric acid is added, the mass of the surface treatment agent is 2.6% of the mass of the silver element in the base solution, and the reaction is continued for 5 minutes to obtain a silver powder suspension;

[0073] The silver powder suspension obtained by the reaction was subjected to solid-liquid separation, washing and suction filtration, and the supernatant after the reaction was removed by sedimentation. The remaining part (silver powder primary product) was washed in the reactor until the conductivity was ≤20μ S / cm, transferred to a disperser, added with alcohol, and stirred for 10 minutes using the disperser. Then, lauric acid (the mass ratio of the silver powder primary product, alcohol and lauric acid was 1:1:0.03) was added and continued to be stirred for 10 minutes. After the stirring was completed, it was washed and suction filtered with alcohol, and the wet powder was placed in a blast drying oven and dried at 65°C for 12 hours. The dried silver powder was crushed and sieved with 200 mesh to obtain a micro-nano spherical silver powder with high surface activity. The scanning electron microscope image thereof is shown in Figure 1 .

[0074] Example 2

[0075] A method for preparing micro-nano spherical silver powder with high surface activity comprises the following steps:

[0076] Dissolve 360 ​​g of silver nitrate in 1005 g of deionized water to obtain a 26 wt % oxidant solution;

[0077] Dissolve 229.5 g of ascorbic acid in 961 g of deionized water to obtain a 19 wt % reducing agent solution;

[0078] Dissolve 35 g of PVP in 1014 g of deionized water to obtain a 3.34 wt % dispersant solution;

[0079] Add 285 ml of 25% ammonia water (the mass ratio of the oxidant solution to the ammonia water is 5.3:1) to the oxidant solution to obtain a 22.16% silver ammonia solution;

[0080] The dispersant solution is added to the silver ammonia solution at a stirring speed of 400 r / min, so that the silver ammonia solution and the dispersant solution are evenly mixed to obtain a base liquid; the mass of the dispersant in the base liquid is 15% of the mass of the silver element, and the mass content of the dispersant in the base liquid is 1.3%;

[0081] Add the reducing agent solution into the bottom solution within 5 seconds; the molar ratio of the reducing agent in the reducing agent solution to the silver element in the bottom solution is 1:1;

[0082] After adding the reducing agent to the base solution, the reaction is continued for 5 minutes, and then the surface treatment agent lauric acid is added, the mass of the surface treatment agent is 1.7% of the mass of the silver element in the base solution, and the reaction is continued for 5 minutes to obtain a silver powder suspension;

[0083] The silver powder suspension obtained by the reaction was subjected to solid-liquid separation, washing and suction filtration, and the supernatant after the reaction was removed by sedimentation. The remaining part (silver powder primary product) was washed in the reactor until the conductivity was ≤20μ S / cm, and then transferred to a disperser, and alcohol was added. After stirring for 10 minutes using the disperser, lauric acid was added (the mass ratio of the silver powder primary product, alcohol and lauric acid was 1:0.7:0.01), and stirring was continued for 10 minutes. After the stirring was completed, it was washed and suction filtered with alcohol, and the wet powder was placed in a blast drying oven and dried at 65°C for 12 hours. The dried silver powder was crushed and sieved with 200 mesh to obtain high surface activity micro-nano spherical silver powder, and its scanning electron microscope image is shown in Figure 2 .

[0084] Example 3

[0085] A method for preparing micro-nano spherical silver powder with high surface activity comprises the following steps:

[0086] Dissolve 240 g of silver nitrate in 960 g of deionized water to obtain a 20 wt % oxidant solution;

[0087] Dissolve 153 g of ascorbic acid in 801 g of deionized water to obtain a 16 wt % reducing agent solution;

[0088] Dissolve 45.6 g of PVP in 1474.4 g of deionized water to obtain a 3 wt % dispersant solution;

[0089] Add 330 ml of 25% ammonia water (the mass ratio of the oxidant solution to the ammonia water is 4:1) to the oxidant solution to obtain a 16% silver ammonia solution;

[0090] The dispersant solution is added to the silver ammonia solution at a stirring speed of 400 r / min, so that the silver ammonia solution and the dispersant solution are evenly mixed to obtain a base liquid; the mass of the dispersant in the base liquid is 30% of the mass of the silver element, and the mass content of the dispersant in the base liquid is 1.5%;

[0091] Add the reducing agent solution into the bottom solution within 5 seconds; the molar ratio of the reducing agent in the reducing agent solution to the silver element in the bottom solution is 1:1;

[0092] After adding the reducing agent to the base solution, the reaction is continued for 5 minutes, and then the surface treatment agent lauric acid is added, the mass of the surface treatment agent is 1% of the mass of the silver element in the base solution, and the reaction is continued for 5 minutes to obtain a silver powder suspension;

[0093] The silver powder suspension obtained by the reaction was subjected to solid-liquid separation, washing and suction filtration, and the supernatant after the reaction was removed by sedimentation. The remaining part (silver powder primary product) was washed in the reactor until the conductivity was ≤20μ S / cm, and then transferred to a disperser, and alcohol was added. After stirring for 10 minutes, lauric acid (the mass ratio of silver powder primary product, alcohol and lauric acid was 1:2:0.04) was added, and stirring was continued for 10 minutes. After the stirring was completed, it was washed and suction filtered with alcohol, and the wet powder was placed in a blast drying oven and dried at 65°C for 12 hours. The dried silver powder was crushed and sieved with 200 mesh to obtain high surface activity micro-nano spherical silver powder, and its scanning electron microscope image is shown in Figure 3 .

[0094] Example 4

[0095] A method for preparing micro-nano spherical silver powder with high surface activity comprises the following steps:

[0096] Dissolve 240 g of silver nitrate in 560 g of deionized water to obtain a 30 wt % oxidant solution;

[0097] Dissolve 153 g of ascorbic acid in 652 g of deionized water to obtain a 19 wt % reducing agent solution;

[0098] Dissolve 45.6 g of PVP in 714 g of deionized water to obtain a 6 wt % dispersant solution;

[0099] Add 440 ml of 25% ammonia water (the mass ratio of the oxidant solution to the ammonia water is 2:1) to the oxidant solution to prepare a 20% silver ammonia solution;

[0100] The dispersant solution is added to the silver ammonia solution at a stirring speed of 400 r / min, so that the silver ammonia solution and the dispersant solution are evenly mixed to obtain a base liquid; the mass of the dispersant in the base liquid is 30% of the mass of the silver element, and the mass content of the dispersant in the base liquid is 2.3%;

[0101] Add the reducing agent solution into the base solution within 5 seconds; the molar ratio of the reducing agent in the reducing agent solution to the silver element in the base solution is 1:1;

[0102] After adding the reducing agent to the base solution, the reaction is continued for 5 minutes, and then the surface treatment agent lauric acid is added, the mass of the surface treatment agent is 1% of the mass of the silver element in the base solution, and the reaction is continued for 5 minutes to obtain a silver powder suspension;

[0103] The silver powder suspension obtained by the reaction was subjected to solid-liquid separation, washing and suction filtration, and the supernatant after the reaction was removed by sedimentation. The remaining part (silver powder primary product) was washed in the reactor until the conductivity was ≤20μ S / cm, transferred to a disperser, added with alcohol, and stirred for 10 minutes using the disperser. Then, lauric acid (the mass ratio of the silver powder primary product, alcohol and lauric acid was 1:1:0.03) was added and continued to be stirred for 10 minutes. After the stirring was completed, it was washed and suction filtered with alcohol, and the wet powder was placed in a blast drying oven and dried at 65°C for 12 hours. The dried silver powder was crushed and sieved with 200 mesh to obtain a micro-nano spherical silver powder with high surface activity. The scanning electron microscope image thereof is shown in Figure 4 .

[0104] Comparative Example 1

[0105] Dissolve 240 g of silver nitrate in 845 g of deionized water to obtain an oxidant solution;

[0106] Dissolve 153 g of ascorbic acid in 801 g of deionized water to obtain a reducing agent solution;

[0107] Dissolve 45.6 g of PVP in 1020 g of deionized water to obtain a dispersant solution;

[0108] The dispersant solution was added into the oxidant solution at a stirring speed of 400 r / min to make the oxidant solution and the dispersant solution evenly mixed to obtain a base solution;

[0109] Add the reducing agent solution to the base solution within 5 seconds;

[0110] After adding the reducing agent solution to the base solution, the reaction is continued for 5 minutes, and then the surface treatment agent lauric acid is added, the mass of the surface treatment agent is 2.6% of the mass of the silver element in the base solution, and the reaction is continued for 5 minutes to obtain a silver powder suspension;

[0111] The silver powder suspension obtained by the reaction was subjected to solid-liquid separation, washing and suction filtration, and the supernatant after the reaction was removed by sedimentation. The remaining part (silver powder primary product) was washed in the reactor until the conductivity was ≤20μ S / cm, and then transferred to a disperser, and alcohol was added. After stirring for 10 minutes using the disperser, lauric acid (the mass ratio of the silver powder primary product, alcohol and lauric acid was 1:1:0.03) was added, and stirring was continued for 10 minutes. After the stirring was completed, it was washed and suction filtered with alcohol, and the wet powder was placed in a blast drying oven and dried at 65°C for 12 hours. The dried silver powder was crushed and sieved through 200 meshes to obtain silver powder, and its scanning electron microscope image is shown in Figure 5 .

[0112] Comparative Example 2

[0113] Compared with Example 1, the difference is that the silver ammonia solution and the reducing agent solution are added to the dispersant solution at the same time. Figure 6 .

[0114] The parameters of the high surface active spherical silver powder prepared in the embodiment of the present invention and the comparative example product are compared, as shown in Table 1:

[0115] Table 1: Particle size, tap density and specific surface area of ​​the silver powder obtained in each embodiment and comparative example

[0116] Test items <![CDATA[D 10 (one)]]> <![CDATA[D 50 (one)]]> <![CDATA[D 90 (one)]]> <![CDATA[D 100 (one)]]> <![CDATA[Tap density (g / cm 3 )]]> <![CDATA[Specific surface area (m 2 / g)]]> Example 1 0.40 0.68 1.15 2.12 3.85 2.37 Example 2 0.32 0.62 1.10 2.12 4.25 2.16 Example 3 0.50 0.82 1.32 1.87 4.93 1.75 Example 4 0.63 1.00 1.56 2.40 4.95 1.71 Comparative Example 1 2.16 3.33 4.98 8.55 5.83 0.47 Comparative Example 2 0.51 0.88 1.51 9.81 5.13 1.67

[0117] The difference between Example 1 and Comparative Example 1 is whether ammonia water is added to the oxidant to prepare the silver nitrate solution into a silver ammonia solution. + Convert to [Ag(NH3)2] + , and quickly add the reducing agent solution, so that the reaction occurs quickly to obtain silver powder with fine particle size and narrow particle size distribution. The difference between Comparative Example 2 and Example 1 is that the base solution is not mixed first, but the silver ammonia solution and the reducing agent solution are added to the dispersant solution at the same time. From the data in Table 1, it can be seen that the particle size distribution of the silver powder obtained in Comparative Example 2 becomes wider.

[0118] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0119] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing micro-nano spherical silver powder with high surface activity, characterized in that: include: Mixing the dispersant with the silver ammonia solution to obtain a mixed solution; Under the condition of continuous stirring, a reducing agent is added to the mixed solution to carry out a first reaction, and then a surface treatment agent is added to carry out a second reaction to obtain a primary product of silver powder; The silver powder primary product, the modified dispersant and the coating agent are mixed to modify the silver powder primary product to obtain micro-nano spherical silver powder with high surface activity; The particle size distribution D50 of the high surface activity micro-nano spherical silver powder is 0.6-1.0 μm, and the specific surface area is not less than 1.7 m 2 / g.

2. The preparation method according to claim 1, characterized in that: include: Under stirring conditions, adding the dispersant solution to the silver ammonia solution and mixing them evenly to obtain the mixed solution; Preferably, the concentration of the dispersant solution is 3-6wt%; Preferably, the mass fraction of the silver ammonia solution is 16-23wt%.

3. The preparation method according to claim 1, characterized in that: The mass of the dispersant in the mixed solution is 5%-50% of the mass of the silver element; and / or, the concentration of the dispersant in the mixed solution is 1.3-2.3wt%; And / or, the dispersant includes any one or a combination of two or more of Tween, polyvinyl pyrrolidone, polyethylene glycol, gelatin, polyvinyl alcohol, gum arabic, and sodium citrate.

4. The preparation method according to claim 1, characterized in that: The silver ammonia solution is obtained by mixing a silver-containing oxidant solution with aqueous ammonia; Preferably, the concentration of the silver-containing oxidant solution is 20-40wt%; Preferably, the mass ratio of the silver-containing oxidant solution to ammonia water is 2-6:1; Preferably, the silver-containing oxidizing agent comprises silver nitrate.

5. The preparation method according to claim 1, characterized in that: include: Under the condition of continuous stirring, adding a reducing agent solution to the mixed solution to carry out the first reaction; Preferably, the stirring speed is 200-600r / min; Preferably, the temperature of the first reaction is room temperature and the time is 5-15 min; Preferably, the molar ratio of the reducing agent in the reducing agent solution to the silver element in the mixed solution is (0.5-2):1; Preferably, the concentration of the reducing agent solution is 16-19wt%; Preferably, the reducing agent includes any one or a combination of two or more of hydrazine hydrate, glucose, ascorbic acid, sodium citrate, sodium hypophosphite, sodium borohydride, hydroquinone, formaldehyde, and acetaldehyde; Preferably, the time for the reducing agent solution to completely enter the mixed solution is 1-30s.

6. The preparation method according to claim 1, characterized in that: The mass of the surface treatment agent is 1%-3% of the mass of the silver element in the mixed solution; And / or, the surface treatment agent includes any one or a combination of two or more of lauric acid, stearic acid, sodium dodecylbenzene sulfonate, oleic acid, palmitic acid, and benzotriazole; And / or, the temperature of the second reaction is room temperature, and the time is 5-15 minutes.

7. The preparation method according to claim 1, characterized in that: include: The silver powder primary product, the modified dispersant and the coating agent are mixed, and stirred and dispersed to modify the silver powder primary product to obtain the high surface activity micro-nano spherical silver powder; Preferably, the mass ratio of the silver powder primary product, the modified dispersant and the coating agent is 1:(0.7-2):(0.01-0.03); Preferably, the modified dispersant includes any one of water and ethanol or a combination of the two; Preferably, the coating agent includes any one or a combination of two or more of lauric acid, stearic acid, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dodecylhydroxystearic acid, sodium dodecylbenzenesulfonate, and oleic acid.

8. The preparation method according to claim 1, characterized in that: include: The silver powder primary product is washed until the conductivity is below 20 μS / cm, and then mixed with the modified dispersant and coating agent to modify the silver powder primary product.

9. The high surface activity micro-nano spherical silver powder prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The particle size distribution D50 of the high surface activity micro-nano spherical silver powder is 0.6-1.0 μm, and the specific surface area is not less than 1.7 m 2 / g.

10. Application of the high surface activity micro-nano spherical silver powder according to claim 9 in solar cells or electronic appliances; Preferably, the application includes: The high-surface-activity micro-nano spherical silver powder is used to prepare silver paste for solar cells.

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