A spherical silver powder with high specific surface area, a preparation method thereof, and a conductive paste

Abstract

The present invention provides a spherical silver powder with a high specific surface area, a preparation method thereof, and a conductive paste, belonging to the technical field of conductive silver powder. The preparation method comprises: dissolving a silver salt in deionized water to obtain an oxidizing solution; dissolving a dispersant in deionized water to obtain a dispersion solution; dissolving a growth agent in deionized water to obtain a growth solution; dissolving a reducing agent in deionized water to obtain a reducing agent solution, adding an acid-base regulator to the reducing agent solution to obtain a reducing solution; mixing the dispersion solution with the growth solution and stirring evenly to form a mixed solution; injecting the oxidizing solution and the reducing solution into the mixed solution, stirring and reacting at 20-60°C for 8-12 minutes to obtain a product solution; filtering the product solution and washing it with water, adding an organic coating agent during the washing process, washing with water for 30-60 minutes, filtering, and drying to obtain a spherical silver powder with a high specific surface area having a protruding structure on the surface. The preparation method is simple, and the spherical silver powder can be used to prepare high-precision conductive line printing paste to meet the printing requirements of the conductive paste.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of conductive silver powder, and particularly relates to a spherical silver powder with a high specific surface area, a preparation method thereof, and a conductive slurry. Background Art

[0002] Electronic paste is a viscous paste made by mixing conductive phase powder, adhesive, solvent and additives in a certain ratio. It is a key material for the production of crystalline silicon solar cells. Among them, silver powder plays a core role as the conductive phase in electronic paste. The morphology, particle size, specific surface area, tap density, burn-in loss and other properties of silver powder will seriously affect the use of the paste. At present, most electronic pastes are printed on the surface of solar cells using the screen printing process. After drying and sintering, metal electrodes are formed. For this kind of high-precision printing, it is often necessary to use a high-viscosity paste. The high-viscosity paste is conducive to forming a high aspect ratio, which places extremely high demands on the morphology and performance of the silver powder, so as to achieve the preparation of high-precision patterns while ensuring printability.

[0003] At present, the existing technology uses liquid phase reduction method to mix conventional components (such as reducing agent, silver salt, dispersant and other components) to prepare silver powder. The specific surface area of the obtained silver powder is relatively small, mostly around 1.0 m 2 / g or less, and the formed electronic paste must be used at a higher temperature to achieve a good sintering effect. It also has problems such as poor conductivity and low aspect ratio, which affect the application effect of silver powder as a conductive filler and cannot meet the needs of high-precision printing. Summary of the Invention

[0004] The present disclosure aims to solve at least one of the technical problems existing in the prior art and provide a spherical silver powder with a high specific surface area, a preparation method thereof, and a conductive paste.

[0005] In one aspect of the present disclosure, a method for preparing spherical silver powder with a high specific surface area is provided, the preparation method comprising:

[0006] Dissolve silver salt in deionized water to obtain an oxidizing solution;

[0007] dissolving a dispersant in deionized water to obtain a dispersion;

[0008] dissolving the growth agent in deionized water to obtain a growth solution;

[0009] dissolving a reducing agent in deionized water to obtain a reducing agent solution, and adding an acid-base regulator to the reducing agent solution to obtain a reducing solution;

[0010] The dispersion liquid and the growth liquid are mixed and stirred to form a mixed solution; the oxidizing solution and the reducing solution are injected into the mixed solution, and the mixture is stirred and reacted at 20-60° C. for 8-12 minutes to obtain a product solution;

[0011] The product solution is filtered and washed with water, and an organic coating agent is added during the washing process. The product solution is washed with water for 30-60 minutes, filtered, and dried to obtain a spherical silver powder with a high specific surface area and a protrusion structure on the surface.

[0012] Optionally, the growth agent is a mixture of a carboxylic acid compound and an inorganic salt.

[0013] Optionally, the carboxylic acid compound includes one or more of formic acid, acetic acid, citric acid, and sodium citrate;

[0014] The inorganic salt includes one or more of potassium oxide, potassium sulfate, potassium carbonate and potassium nitrate.

[0015] Optionally, the reducing agent includes one or more of ascorbic acid, sodium ascorbate, formaldehyde, sodium borohydride, and hydrazine hydrate.

[0016] Optionally, the dispersant includes one or more of polyvinyl pyrrolidone, gelatin, gum arabic, and polyvinyl alcohol.

[0017] Optionally, the organic coating agent includes one or more of stearic acid, palmitic acid, tyrosine, myristic acid, oleic acid, and lauric acid.

[0018] Optionally, the silver salt includes one or more of silver nitrate, silver fluoride, silver sulfate, and silver perchlorate.

[0019] Optionally, the concentration of the oxidizing solution is 0.2-0.5M;

[0020] The concentration of the reducing agent solution is 0.1-0.4M;

[0021] The concentration of the dispersion is 0.2-0.8 mM;

[0022] The concentration of the growth solution is 0.05-1M.

[0023] Optionally, an acid-base regulator is added to the reducing agent solution, comprising:

[0024] mixing an acid-base regulator with a solvent to form an acid-base regulator solution;

[0025] Adding an acid-base adjusting agent solution into the reducing agent solution.

[0026] Optionally, the concentration of the acid-base regulator solution is 0.01-1M.

[0027] Optionally, an organic coating agent is added during the water washing process, including:

[0028] mixing an organic capping agent with a solvent to form an organic capping agent solution;

[0029] The organic coating agent solution is added during the water washing process.

[0030] Optionally, the concentration of the organic coating agent solution is 0.01-0.1M.

[0031] Another aspect of the present disclosure provides a spherical silver powder with a high specific surface area, wherein the spherical silver powder with a high specific surface area is prepared by the method described above; wherein,

[0032] The specific surface area of the high specific surface area spherical silver powder is 1.4-1.6m 2 / g.

[0033] Optionally, the surface of the high specific surface area spherical silver powder contains an organic coating agent.

[0034] Another aspect of the present disclosure provides a conductive paste, which includes conductive powder, adhesive, solvent and additives; wherein,

[0035] The conductive powder adopts the high specific surface area spherical silver powder described above. The present disclosure provides a high specific surface area spherical silver powder and its preparation method and conductive paste. The preparation method comprises: dissolving a silver salt in deionized water to obtain an oxidizing solution; dissolving a dispersant in deionized water to obtain a dispersion; dissolving a growth agent in deionized water to obtain a growth solution; dissolving a reducing agent in deionized water to obtain a reducing agent solution, adding an acid-base regulator to the reducing agent solution to obtain a reducing solution; mixing the dispersion with the growth solution and stirring evenly to form a mixed solution; injecting the oxidizing solution and the reducing solution into the mixed solution, stirring and reacting at 20-60°C for 8-12 minutes to obtain a product solution; filtering and washing the product solution with water, adding an organic coating agent during the washing process, washing with water for 30-60 minutes, filtering, and drying to obtain a high specific surface area spherical silver powder with a protruding structure on the surface. The preparation method is simple, and the resulting high specific surface area spherical silver powder can be used to prepare high-precision conductive line printing paste to meet the printing requirements of the conductive paste. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flowchart of a method for preparing spherical silver powder with high specific surface area according to an embodiment of the present disclosure;

[0037] Figure 2 The microscopic morphology of the high specific surface area spherical silver powder according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0038] To help those skilled in the art better understand the technical solutions of the present disclosure, the present disclosure is further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a portion of the embodiments of the present disclosure, not all of them. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without the need for creative work are within the scope of protection of the present disclosure.

[0039] Unless otherwise specified, technical or scientific terms used in this disclosure shall have the ordinary meanings understood by persons having ordinary skills in the field to which this disclosure belongs. The terms "include" or "comprising" used in this disclosure do not limit the shapes, numbers, steps, operations and / or groups thereof mentioned, nor do they exclude the presence or addition of one or more other different shapes, numbers, steps, operations and / or groups thereof.

[0040] like Figure 1 As shown, one aspect of the present disclosure provides a method S100 for preparing spherical silver powder with high specific surface area, which specifically includes the following steps S110 to S160:

[0041] S110, dissolving silver salt in deionized water to obtain oxidizing solution A.

[0042] In some preferred embodiments, the silver salt includes one or more of silver nitrate, silver fluoride, silver sulfate, and silver perchlorate. That is, the silver salt can be a single silver-containing compound or a mixture of several compounds.

[0043] In other preferred embodiments, the concentration of the oxidizing solution is 0.2-0.5M, that is, the silver salt is dissolved in water to form an oxidizing solution with a silver ion concentration of 0.2-0.5M, wherein the concentration of the oxidizing solution may preferably be 0.2M, 0.3M, 0.4M, 0.5M, etc.

[0044] S120, dissolving the dispersant in deionized water to obtain dispersion B.

[0045] In some preferred embodiments, the dispersant includes one or more of polyvinyl pyrrolidone, gelatin, gum arabic, and polyvinyl alcohol.

[0046] In other preferred embodiments, the concentration of the dispersion is 0.2-0.8 mM, that is, the dispersant is dissolved in water to form a dispersion with a concentration of 0.2-0.8 mM, wherein the concentration of the dispersion may preferably be 0.2 mM, 0.3 mM, 0.5 mM, 0.6 mM, or 0.8 mM.

[0047] S130, dissolving the growth agent in deionized water to obtain a growth solution C.

[0048] In some preferred embodiments, the growth agent is a mixture of a carboxylic acid compound and an inorganic salt. The interaction between the two is conducive to promoting the formation of protrusions on the surface of the silver powder, forming spherical silver powder with a large specific surface area.

[0049] As a further preferred embodiment, the carboxylic acid compound can be a carboxylic acid, such as formic acid, acetic acid, or citric acid; of course, the carboxylic acid compound can also be a carboxylate, such as sodium citrate. In other words, the carboxylic acid compound can be any carboxylic acid or a mixture of multiple carboxylic acids, or any carboxylate or a mixture of multiple carboxylates. Of course, it can also be a mixture of at least one carboxylic acid and at least one carboxylate, and this is not specifically limited.

[0050] As a further preferred embodiment, the inorganic salt includes one or more of potassium oxide, potassium sulfate, potassium carbonate, and potassium nitrate, which are not specifically limited.

[0051] In other preferred embodiments, the concentration of the growth solution is 0.05-1 M. That is, the carboxylic acid organic compound and the inorganic salt are simultaneously dissolved in deionized water to form a growth solution with a concentration of 0.05-1 M. The concentration of the growth solution may preferably be 0.05 M, 0.1 M, 0.15 M, 0.2 M, 0.3 M, 0.5 M, 0.6 M, 0.7 M, 0.08 M, 0.9 M, 1 M, etc.

[0052] As a further preferred embodiment, the concentration of the growth solution is preferably 0.1M.

[0053] S140, dissolving a reducing agent in deionized water to obtain a reducing agent solution, and adding an acid-base regulator to the reducing agent solution to obtain a reducing solution D.

[0054] In some preferred embodiments, the reducing agent includes one or more of ascorbic acid, sodium ascorbate, formaldehyde, sodium borohydride, and hydrazine hydrate.

[0055] In other preferred embodiments, the concentration of the reducing agent solution is 0.1-0.4M, that is, the reducing agent is dissolved in water to form a reducing agent solution with a concentration of 0.1-0.4M, wherein the concentration of the reducing agent solution may preferably be 0.1M, 0.2M, 0.3M, 0.4M, etc.

[0056] In other preferred embodiments, the acid-base regulator includes one or a mixture of sodium hydroxide, ammonia water, nitric acid, and hydrochloric acid.

[0057] It should be understood that the order in which the acid-base modifier is added to the reducing agent solution is not specifically limited, as long as it is added before the oxidizing solution and the reducing solution are mixed to adjust the pH of the reducing solution. For example, after each reserve solution is prepared and it is necessary to mix the reserve solutions for reaction, the acid-base modifier can be added to the reducing agent solution to adjust the pH of the reaction solution during the reaction. Of course, the acid-base modifier can also be added directly to the reducing agent solvent after the reducing agent solvent is prepared to obtain the reducing solution.

[0058] It should be noted that this embodiment does not specifically limit the form of adding the acid-base regulator. The acid-base regulator solid can be directly added to the reducing agent solution. Of course, in order to make the acid-base regulator evenly dispersed in the reducing agent solution, the acid-base regulator solid can also be first dissolved in the corresponding solvent to form an acid-base regulator solution, and then the acid-base regulator solution is added to the reducing agent solution.

[0059] In some preferred embodiments, the acid-base regulator is added in the form of a solution. In this case, the acid-base regulator is added to the reducing agent solution to form a reducing solution, which includes the following specific steps:

[0060] dissolving an acid-base adjusting agent in a solvent (e.g., deionized water) to form an acid-base adjusting agent solution;

[0061] Acid-base regulator solution is added to the reducing agent solution to form a reducing solution.

[0062] In other preferred embodiments, the concentration of the acid-base regulator solution is preferably 0.01-1M, for example, 0.01M, 0.03M, 0.04M, 0.06M, 0.08M, 1M.

[0063] It should be noted that this embodiment does not specifically limit the order of the above steps S110 to S140. The steps can be performed simultaneously to synchronously form the above standby solution, or the standby solutions can be formed in different orders.

[0064] S150, mixing the dispersion liquid and the growth liquid, stirring evenly to form a mixed solution; injecting the oxidizing liquid and the reducing liquid into the mixed solution, stirring and reacting at 20-60° C. for 8-12 minutes to obtain a product solution.

[0065] Specifically, dispersion liquid B and growth liquid C are added to a constant temperature reactor, and the dispersion liquid B and growth liquid C are stirred evenly by an agitator to obtain a mixed solution; at the same time, oxidation liquid A and reduction liquid D are injected into the constant temperature reactor at a rate of 0.1-0.5 L / h by a peristaltic pump to obtain a silver-gray solution, i.e., the product solution.

[0066] In some preferred embodiments, the reaction temperature is preferably 20°C, 30°C, 40°C, 50°C, or 60°C.

[0067] As a further preferred embodiment, the reaction temperature is preferably 30°C.

[0068] In other embodiments, the reaction time is preferably 8 min, 9 min, 10 min, 11 min, or 12 min.

[0069] As a further preferred embodiment, the reaction time is preferably 10 min.

[0070] In this embodiment, the dispersion liquid and the growth liquid are first mixed, and then the oxidizing liquid and the reducing liquid are added to the mixed solution by injection to ensure that the solutions are fully mixed. At the same time, by controlling the reaction rate, a protrusion structure is formed on the powder surface while forming spherical silver powder, thereby effectively increasing the specific surface area of the spherical silver powder.

[0071] S160, filtering the product solution, washing with water, adding an organic coating agent during the washing process, washing with water for 30-60 minutes, filtering, and drying to obtain a spherical silver powder with a high specific surface area and a protruding structure on the surface.

[0072] Specifically, the product solution is filtered through filter paper to filter out the silver powder, and the silver powder is repeatedly washed with water for 3-5 times. An organic coating agent is added in the last water washing. The organic coating agent is evenly coated on the silver powder to play a dispersing role, thereby preventing the silver powder from thermally agglomerating during the drying process. At the same time, the organic coating agent can better combine the silver powder with the glass powder and the organic carrier, thereby making the performance of the silver paste on the screen more excellent.

[0073] In some preferred embodiments, the organic coating agent includes one or more of stearic acid, palmitic acid, tyrosine, myristic acid, oleic acid, and lauric acid.

[0074] It should be noted that the present embodiment does not specifically limit the form of adding the organic coating agent. The organic coating agent solid can be directly added during the water washing process. Of course, the organic coating agent solid can also be first dissolved in a corresponding solvent to form an organic coating agent solution, and then the organic coating agent solution can be added to the water washing process to make it more evenly coated on the silver powder.

[0075] In some preferred embodiments, the organic coating agent is added in the form of a solution during the water washing process. In this case, the organic coating agent is added during the water washing process, comprising the following specific steps:

[0076] dissolving the organic coating agent in a solvent to form an organic coating agent solution;

[0077] The organic coating agent solution is added during the last water wash.

[0078] In other preferred embodiments, the concentration of the organic capping agent solution is preferably 0.01-0.1 M, for example, 0.01 M, 0.03 M, 0.05 M, 0.07 M, 0.09 M, 0.1 M, etc.

[0079] It is worth noting that the spherical silver powder prepared in this embodiment has a dense structure inside, good structural stability and high tap density, and there are protrusions on the surface of the silver powder, which increases its specific surface area and meets the needs of high-precision printing.

[0080] In this embodiment, by adding a growth agent component during the preparation process, it works synergistically with other components to facilitate the formation of spherical silver powder with a high specific surface area, thereby ensuring that the conductive paste has a high aspect ratio while meeting high sintering activity requirements.

[0081] In another aspect of the present disclosure, a spherical silver powder with a high specific surface area is provided. The spherical silver powder with a high specific surface area is prepared by the preparation method described above. For the specific preparation process, please refer to the above description and will not be repeated here.

[0082] like Figure 2 As shown in the figure, the surface of the spherical silver powder disclosed in the present invention is not smooth, but has an uneven protrusion structure. The particle size D10 of the spherical silver powder is 0.7-1.0 μm, D50 is 1.3-1.6 μm, D90 is 2.4-2.7 μm, the tap density is 3.9-4.5 g / mL, and the specific surface area is 1.4-1.6 m 2 / g.

[0083] Furthermore, the surface of the spherical silver powder disclosed herein contains an organic coating agent. When the silver powder is used in a conductive paste, the organic coating agent component on the surface can better combine the silver powder with the glass powder and the organic carrier, thereby making the performance of the silver paste on the screen more excellent.

[0084] Another aspect of the present disclosure provides a conductive paste comprising conductive powder, a binder, a solvent, and an additive; wherein the conductive powder is the high specific surface area spherical silver powder described above.

[0085] In this embodiment, the spherical structure of the prepared silver powder ensures high sintering activity in the conductive paste, reducing the sintering temperature. Furthermore, the large specific surface area of the silver powder facilitates the preparation of a high-viscosity paste, increasing the aspect ratio of the printed line shape of the conductive paste and further improving the printability of the conductive paste. Furthermore, when the highly active spherical silver powder is used as the conductive phase in the conductive paste, the conductive properties of the conductive paste can be improved, thereby increasing the photoelectric conversion efficiency of the crystalline solar cell.

[0086] The preparation method of spherical silver powder with high specific surface area will be further described below with reference to several specific examples:

[0087] Example 1

[0088] The method for preparing the spherical silver powder with high specific surface area in this example includes the following steps:

[0089] S1. Dissolve nitrate in deionized water to obtain an oxidizing solution A with a concentration of 0.3 M;

[0090] S2. Dissolve polyvinyl pyrrolidone in deionized water to obtain a dispersion B with a concentration of 0.5 mM;

[0091] S3, taking a mixture of citric acid and potassium sulfate as a growth agent, dissolving the growth agent in deionized water to obtain a growth solution C with a concentration of 0.15 ml;

[0092] S4, dissolving ascorbic acid in deionized water to obtain a reducing agent solution with a concentration of 0.2 M;

[0093] S5. Adding a 0.08 M sodium hydroxide solution to the reducing agent solution to obtain a reducing solution D;

[0094] S6. First, add dispersion liquid B and growth liquid C into the reactor and stir them with a stirrer to evenly mix them. Then, use a peristaltic pump to simultaneously inject oxidation liquid A and reduction liquid D into the thermostatic reactor at a rate of 0.1-0.5 L / h. The reaction temperature is 30°C and the reaction is stirred for 10 minutes to obtain a silver-gray solution.

[0095] S7. Filter the silver-gray solution through filter paper to filter out the silver powder, then wash with water, repeat 3-5 times, add 0.05M stearic acid solution in the last wash, wash with water for 30-60 minutes, and finally filter and dry to obtain the desired silver powder.

[0096] As shown in Table 1, the specific surface area of the spherical silver powder obtained in Example 1 is 1.6 m 2 / g, tap density is 4.5g / mL, silver powder particle size D10 = 0.86μm, D50 = 1.43μm, D90 = 2.54μm.

[0097] Example 2

[0098] The preparation method of the high specific surface area spherical silver powder in this example is the same as that in Example 1, except that the reaction temperature in step S6 is changed to 20°C.

[0099] As shown in Table 1, the specific surface area of the spherical silver powder obtained in Example 2 is 1.43 m 2 / g, tap density is 3.95g / mL, silver powder particle size D10 = 0.78μm, D50 = 1.37μm, D90 = 2.48μm.

[0100] Example 3

[0101] The preparation method of the high specific surface area spherical silver powder in this example is the same as that in Example 1, except that the reaction temperature in step S6 is changed to 60°C.

[0102] As shown in Table 1, the specific surface area of the spherical silver powder obtained in Example 3 is 1.5 m 2 / g, tap density is 4.1g / mL, silver powder particle size D10 = 0.95μm, D50 = 1.53μm, D90 = 2.64μm.

[0103] Compared with Example 1, as the reaction temperature increases, the specific surface area and tap density of the spherical silver powder decrease, while the particle size increases. This shows that the relatively high reaction temperature helps promote the growth of the spherical silver powder, but has a limited effect on the formation of protrusions on the surface of the silver powder. As a result, the specific surface area of the spherical silver powder formed at the above reaction temperature is lower than that of the spherical silver powder formed in Example 1.

[0104] Comparative Example 1

[0105] The preparation method of the spherical silver powder in this example is the same as that in Example 1, except that the reaction temperature in step S6 is changed to 10°C.

[0106] As shown in Table 1, the specific surface area of the spherical silver powder obtained in Comparative Example 1 is 1.26 m 2 / g, tap density is 3.8g / mL, silver powder particle size D10 = 0.64μm, D50 = 1.35μm, D90 = 2.44μm.

[0107] Compared with Examples 1-3, when the reaction temperature is lower than 20°C, the specific surface area, tap density and particle size of the silver powder are reduced to varying degrees, but its specific surface area is still higher than 1 m 2 / g.

[0108] Comparative Example 2

[0109] The preparation method of the spherical silver powder in this example is the same as that in Example 1, except that the reaction temperature in step S6 is changed to 70°C.

[0110] As shown in Table 1, the specific surface area of the spherical silver powder obtained in Comparative Example 2 is 1.15 m 2 / g, tap density is 3.6g / mL, silver powder particle size D10 = 0.77μm, D50 = 1.18μm, D90 = 1.84μm.

[0111] Compared with Examples 1-3, when the reaction temperature is higher than 60°C, the specific surface area, tap density and particle size of the silver powder are reduced to varying degrees, but its specific surface area is still higher than 1m 2 / g.

[0112] In summary, according to Examples 1-3 and Comparative Examples 1-2, it can be seen that in the process of preparing spherical silver powder, the reaction temperature is preferably 20-60°C, and the specific surface area of the spherical silver powder formed in this temperature range is 1.4 m 2 / g or above, with a larger specific surface area, tap density, and particle size.

[0113] Comparative Example 3

[0114] The preparation method of the spherical silver powder in this example is the same as that in Example 1, except that step S3 is removed, that is, no growth agent is added, and the concentration of the growth solution is 0.

[0115] As shown in Table 1, the specific surface area of the spherical silver powder obtained in this comparative example 3 is 0.8 m 2 / g, tap density is 3.45g / mL, silver powder particle size D10 = 0.69μm, D50 = 1.21μm, D90 = 1.95μm.

[0116] Compared with Examples 1-3 and Comparative Examples 1-2, when no growth agent is added during the preparation of spherical silver powder, the specific surface area, tap density and particle size of the obtained silver powder are significantly reduced, and the specific surface area is less than 1m 2 / g, which shows that the growth agent plays a vital role in increasing the specific surface area of silver powder. During the preparation process, the addition of growth agent can effectively promote the formation of protrusion structure on the surface of silver powder and increase the specific surface area.

[0117] Table 1 Specific surface area, tap density and particle size results of spherical silver powder

[0118]

[0119] The present invention discloses a spherical silver powder with high specific surface area, a preparation method thereof, and a conductive paste, which have the following advantages over the prior art: the preparation process of the present invention is simple, and the spherical silver powder with high specific surface area is prepared by liquid phase reduction method, and its specific surface area can reach 1.6m 2 / g, can form a conductive paste with higher viscosity, which is beneficial to improve the aspect ratio, so as to achieve the preparation of high-precision patterns while ensuring printability. At the same time, it also has higher sintering activity and higher conductivity, which can reduce the sintering temperature of the conductive paste, solving the current problems of poor conductive performance and low aspect ratio of the conductive paste.

[0120] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present disclosure, and the present disclosure is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present disclosure, and such modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A method for preparing spherical silver powder with high specific surface area, characterized in that: The preparation method comprises: Dissolve silver salt in deionized water to obtain an oxidizing solution; dissolving a dispersant in deionized water to obtain a dispersion; dissolving the growth agent in deionized water to obtain a growth solution; dissolving a reducing agent in deionized water to obtain a reducing agent solution, and adding an acid-base regulator to the reducing agent solution to obtain a reducing solution; The dispersion liquid and the growth liquid are mixed and stirred to form a mixed solution; the oxidizing liquid and the reducing liquid are injected into the mixed solution, and the mixture is stirred and reacted at 20-60° C. for 8-12 minutes to obtain a product solution; the growth agent is a mixture of a carboxylic acid compound and an inorganic salt, and the inorganic salt includes one or more of potassium oxide, potassium sulfate, potassium carbonate, and potassium nitrate; The product solution is filtered and washed with water, and an organic coating agent is added during the washing process. The product solution is washed with water for 30-60 minutes, filtered, and dried to obtain a high specific surface area spherical silver powder with a dense internal structure and a protruding structure on the surface. The specific surface area of the high specific surface area spherical silver powder is 1.4-1.6 m 2 / g.

2. The preparation method according to claim 1, characterized in that The carboxylic acid compound includes one or more of formic acid, acetic acid, citric acid, and sodium citrate.

3. The preparation method according to claim 1, characterized in that The reducing agent includes one or more of ascorbic acid, sodium ascorbate, formaldehyde, sodium borohydride and hydrazine hydrate.

4. The preparation method according to claim 1, characterized in that The dispersant includes one or more of polyvinyl pyrrolidone, gelatin, gum arabic, and polyvinyl alcohol.

5. The preparation method according to claim 1, characterized in that The organic coating agent includes one or more of stearic acid, palmitic acid, tyrosine, myristic acid, oleic acid, and lauric acid.

6. The preparation method according to claim 1, characterized in that The silver salt includes one or more of silver nitrate, silver fluoride, silver sulfate, and silver perchlorate.

7. The preparation method according to any one of claims 1 to 6, characterized in that The concentration of the oxidizing solution is 0.2-0.5M; The concentration of the reducing agent solution is 0.1-0.4M; The concentration of the dispersion is 0.2-0.8 mM; The concentration of the growth solution is 0.05-1M.

8. A spherical silver powder with high specific surface area, characterized in that: The high specific surface area spherical silver powder is prepared by the preparation method according to any one of claims 1 to 7.

9. A conductive paste, characterized in that: The conductive paste includes conductive powder, adhesive, solvent and additives; wherein, The conductive powder is the spherical silver powder with high specific surface area as claimed in claim 8.

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