Micro-nano silver coated copper conductive powder and preparation method and application thereof

Abstract

The invention relates to micro-nano silver coated copper conductive powder and a preparation method and application thereof.The preparation method comprises the steps that carbon dioxide serves as an acid-base regulator to dynamically regulate and control the precipitation and separation process of a copper precursor to obtain a basic copper carbonate carrier material, and basic copper carbonate loaded silver carbonate precipitate is obtained through cation exchange of a silver source; and carrying out chemical reduction, solid-liquid separation, washing and drying to obtain the micro-nano silver coated copper conductive powder. Compared with the prior art, the method is based on the acidity and precipitation effects of CO2, operation is easy, green and environment-friendly, and the prepared micro-nano silver-coated copper conductive powder is narrow in particle size distribution, high in conductivity, low in silver content and good in stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-nano metal materials, and particularly to a micro-nano silver-coated copper conductive powder, a preparation method thereof and an application thereof. BACKGROUND

[0002] The micro-nano silver powder has high conductivity and good chemical stability, but the high cost and silver migration phenomenon limit its application to a certain extent. The conductivity of copper powder is close to that of silver powder, and the cost is low, but the copper powder is easy to oxidize in the preparation and use process, thereby reducing the service life of the material. The silver-coated copper powder is a multifunctional metal powder. By coating silver on the surface of copper powder, a composite material with special structure and properties is formed. The silver-coated copper powder not only overcomes the migration of silver powder and the oxidation characteristics of copper powder, but also has the advantages of low cost, high conductivity, good stability, etc. It is a high-conductive powder material with great development potential, which can be used in various conductive, electromagnetic shielding products such as ink, paint, adhesive, plastic, etc.

[0003] At present, the preparation methods of silver-coated copper powder mainly include chemical plating, electroplating, vapor deposition, mechanical ball milling, melt spraying, spraying, etc. The chemical plating method is to coat a layer of substance (silver) on the surface of the plated object (copper) by chemical method. The surface coating is not uniform and dense, and the oxidation resistance is not strong. Usually, dispersants and complexing agents need to be introduced. The mechanical ball milling method is to add prepared silver powder and copper powder into the equipment in proportion, so as to realize the purpose of silver-coated copper powder. However, the distribution is uneven, and the consumption of silver is high. The melt spraying method is to heat copper and silver to a molten state, and then realize the coating of silver on copper through atomization. This method can prepare silver-coated copper powder with low silver content, but the cost is high and the operation is complex.

[0004] Patent CN102211185B uses vapor deposition method to prepare spherical or spherical silver-coated copper alloy powder with an average particle size of 0.05-2 microns by evaporating copper and silver. However, the operation temperature of this method is high due to the boiling points of copper and silver being 2575℃ and 2212℃ respectively. Patent CN106148926B uses chemical plating method to prepare silver-coated copper powder. The copper powder is treated by alkaline washing, and silver-coated copper powder is obtained by introducing dispersants, complexing agents and coupling agents. However, the morphology of the product after silver plating is affected by the morphology of the copper powder raw material to be plated with silver. Patent CN113020587B introduces N times of silver coating treatment to copper powder to obtain silver-coated copper powder with dense silver layer, and the mass percentage of silver is about 5%-30%. However, the operation steps are complicated. Patent CN110551995B uses copper powder and silver nitrate as raw materials, ascorbic acid, glucose or formaldehyde as reducing agent, and obtains high-density silver-coated copper particles by one-pot chemical electroplating at room temperature. The mass ratio of silver to copper is 0.6-0.8:1. However, the storage of nano-silver suspension needs to strictly control the environmental conditions.

[0005] Patent application CN114535571A discloses a kind of micron silver-coated copper powder and its preparation method and application, preparation method includes the following steps: (1) mixed micro-nano copper powder, ammonium salt, reducing agent, ammonia and solvent, then ultrasonic and stirring are carried out in turn to obtain copper powder mixture liquid;(2) in the stirring state, drop silver source solution to the copper powder mixture liquid obtained in step (1) to carry out first reaction, then mix the protective agent solution, in turn carry out secondary reaction, stop stirring and sedimentation, obtain micron silver-coated copper powder precursor;(3) the micron silver-coated copper powder precursor obtained in step (2) is treated, to obtain the micron silver-coated copper powder.The preparation method of micron silver-coated copper powder provided by the application is simple, does not need heating, easy to scale production, and the micron silver-coated copper powder prepared has dense silver plating layer, complete coating, low resistivity and good oxidation resistance.However, the obtained sample has single morphology and micron particle size.

[0006] Therefore, it is an urgent problem in the field to prepare low-cost, well-stable silver-coated copper powder conductive powder by innovative method and provide its comprehensive application performance. SUMMARY

[0007] The purpose of the present application is to provide a kind of micro-nano silver-coated copper conductive powder and its preparation method and application, with low cost, high conductivity, good stability and other advantages.

[0008] The purpose of the present application can be realized by the following technical scheme: a kind of micro-nano silver-coated copper conductive powder preparation method, carbon dioxide (CO2) is used as acid-base regulator to dynamically control the precipitation process of copper precursor to obtain basic copper carbonate carrier material, and the cation exchange of silver source is carried out to obtain basic copper carbonate loaded silver carbonate Cu x Ag y (OH)2(CO3) precipitation, chemical reduction, solid-liquid separation, washing and drying to obtain the micro-nano silver-coated copper conductive powder.

[0009] Preferably, the preparation method of the micro-nano silver-coated copper conductive powder comprises the following steps:

[0010] (1) preparation of basic copper carbonate loaded silver carbonate precipitation: copper precursor and silver source are added to alkaline organic amine solution to obtain a mixture, carbon dioxide gas is introduced into the mixture, and basic copper carbonate loaded silver carbonate precipitation is obtained by reaction, and the chemical reaction formula is as follows:

[0011] Cu 2+ / Cu + +OH - +CO2→Cu2(OH)2(CO3)↓;

[0012] Cu2(OH)2(CO3)+Ag+ → Cu x Ag y (OH)2(CO3)↓;

[0013] wherein, x = 1.5-2, y = 0-1;

[0014] (2) Preparation of the micro-nano silver-coated copper conductive powder: adding a reducing agent to the system of step (1), and obtaining the micro-nano silver-coated copper conductive powder through solid-liquid separation, washing, and drying.

[0015] Further preferably, y = 0.1-1 in step (1).

[0016] Further preferably, the concentration of the copper precursor in the mixed solution in step (1) is 0.005 mol / L-1.5 mol / L.

[0017] Further preferably, the concentration of the silver source in the mixed solution in step (1) is 0.001-1 mol / L.

[0018] Further preferably, the mixing mode of the copper precursor, the silver source, and the alkaline organic amine solution in step (1) is one or two of stirring, ultrasonic, and microwave.

[0019] Further preferably, the concentration of the carbon dioxide gas in step (1) is higher than 400 ppm, and the gas flow rate is 1-100 L / min.

[0020] Further preferably, the carbon dioxide gas in step (1) is introduced in the form of carbon dioxide / nitrogen mixed gas.

[0021] Further preferably, the reaction time in step (1) is 0.5-24 h, and the reaction temperature is room temperature-80℃.

[0022] Further preferably, the mixed solution in step (1) is heated and carbon dioxide gas is introduced thereinto, and the reaction temperature is 30-80℃.

[0023] Further preferably, the organic amine in step (1) is one or a combination of several of ethanolamine, diethanolamine, triethanolamine, ethylenediamine, diethylamine, triethylamine, and N-methylethanolamine.

[0024] Further preferably, the mass fraction of the organic amine in the alkaline organic amine solution in step (1) is 2-80 wt%.

[0025] Further preferably, the solvent of the alkaline organic amine solution in step (1) is deionized water.

[0026] Further preferably, the reducing agent in step (2) is one or more of hydrazine hydrate, glucose, ascorbic acid, formic acid, sodium ascorbate, potassium ascorbate, ferrous sulfate, sodium sulfite, sodium dithionite, sodium thiosulfate, sodium hypophosphite, potassium hypophosphite, diborane, sodium borohydride, hydrogen, or synthetic gas.

[0027] Further preferably, the concentration of the reducing agent in step (2) is 0.01-1 mol / L, and the reduction process is achieved under ultrasonic-assisted stirring at 30-100°C for 0.1-12 hours.

[0028] Preferably, the copper precursor is one or two of copper acetate, copper hydroxide, copper nitrate, copper chloride, copper oxide, cuprous oxide, copper sulfide, cuprous sulfide, copper sulfate, cuprous sulfate, or copper acetylacetonate.

[0029] Further preferably, the copper precursor is one or two of copper acetate, copper hydroxide, copper nitrate, copper chloride, copper oxide, copper sulfate, or copper acetylacetonate.

[0030] The chemical reaction formula for generating the basic copper carbonate loaded silver carbonate precipitate is as follows:

[0031] CuX+OH - +CO2→Cu2(OH)2(CO3)↓;

[0032] Cu2(OH)2(CO3)+Ag + →Cu x Ag y (OH)2(CO3)↓;

[0033] X=(OAc)2, (OH)2, (NO3)2, Cl2, O, SO4, (acac)2.

[0034] Preferably, the silver source is one of silver nitrate, silver acetate, silver ammine solution, or silver sulfate.

[0035] Preferably, after obtaining the basic copper carbonate loaded silver carbonate precipitate, the micro-nano silver-coated copper conductive powder is obtained through chemical reduction, solid-liquid separation, surface treatment, washing, and drying.

[0036] Further preferably, after solid-liquid separation, the obtained wet powder is dispersed in a solvent to obtain a 0.001-20 wt% silver-coated copper powder suspension, 0-5 wt% of a surface treatment agent is added, and continuous stirring is performed at 30-80°C for 0.01-6 hours, repeated filtration and washing are performed, and drying is performed at 50-120°C for 1-6 hours to obtain the micro-nano silver-coated copper conductive powder.

[0037] More preferably, the surface treatment agent comprises at least one of polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid.

[0038] More preferably, the solvent is one or more of deionized water, methanol, ethanol, acetic acid, ethyl acetate, acetone, toluene, and xylene.

[0039] Preferably, the solid-liquid separation method comprises one of centrifugation, suction filtration, and pressure filtration.

[0040] Preferably, the washing solvent is one or more of deionized water, ethanol, acetic acid, and dilute sulfuric acid solution.

[0041] A micro-nano silver-coated copper conductive powder is prepared by the above method, and the micro-nano silver-coated copper conductive powder has a particle size in the range of 10 nm-20 mu m and a spherical, round cake, spindle or flaky morphology.

[0042] The micro-nano silver-coated copper conductive powder is used in conductive ink, conductive paste, conductive adhesive and photovoltaic paste.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] 1. The present application provides a preparation method of a low-cost, high-conductivity and good-stability micro-nano silver-coated copper conductive powder, which is based on the acidity and precipitation of CO2 and is simple to operate and green and environmentally friendly, and the prepared micro-nano silver-coated copper conductive powder has a narrow particle size distribution, high conductivity, low silver content and good stability.

[0045] 2. The present application uses low-concentration CO2 as an acid-base regulator, which can utilize CO2 in flue gas or even air, thereby helping to reduce the concentration of CO2 in the environment and alleviate the greenhouse effect.

[0046] 3. The present application can obtain micro-nano silver-coated copper conductive powders with different particle sizes and morphologies by adjusting the composition, concentration and operating conditions of the organic amine solution, which can meet the requirements of silver-coated copper conductive powders in different fields.

[0047] 4. The present application uses a copper precursor as a raw material, and the morphology of the product after silver plating is not affected by the morphology of the copper raw material, so that micro-nano silver-coated copper conductive powders with different particle sizes and morphologies can be obtained.

[0048] 5. The silver of the micro-nano silver-coated copper conductive powder is uniformly and densely coated on the surface of the copper, and has strong oxidation resistance.

[0049] 6. The present application has a relatively low silver consumption, does not need to strictly control the storage environment of the raw material, does not need to introduce a dispersant and a complexing agent, has low cost, and is simple to operate and green and environmentally friendly. Attached Figure Description

[0050] Figure 1 This is a SEM image of the micro / nano silver-coated copper conductive powder in Example 1 of the present invention.

[0051] Figure 2 This is an EDS-MAPPING diagram of the micro / nano silver-coated copper conductive powder in Example 1 of the present invention.

[0052] Figure 3 This is an SEM image of the micro / nano silver-coated copper conductive powder in Example 2 of the present invention.

[0053] Figure 4 This is an EDS-MAPPING diagram of the micro / nano silver-coated copper conductive powder in Example 2 of the present invention.

[0054] Figure 5 This is a SEM image of the micro / nano silver-coated copper conductive powder in Example 3 of the present invention.

[0055] Figure 6 This is an SEM image of the micro / nano silver-coated copper conductive powder in Example 4 of the present invention. Detailed Implementation

[0056] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0057] A method for preparing micro / nano silver-coated copper conductive powder involves using CO2 as an acid-base regulator to dynamically control the precipitation process of Cu salts to obtain a basic copper carbonate carrier material, followed by cation exchange with silver salts to obtain Cu. x Ag y (OH)2(CO3) precipitate, followed by chemical reduction, solid-liquid separation, washing, and drying to obtain micro / nano silver-coated copper conductive powder with uniform particle size and controllable morphology.

[0058] The chemical reaction formula is as follows:

[0059] CuX+OH - +CO2→Cu2(OH)2(CO3)↓;

[0060] Cu2(OH)2(CO3)+Ag + →Cu x Ag y (OH)2(CO3)↓;

[0061] X=(OAc)2,(OH)2,(NO3)2,Cl2,O,SO4,(acac)2.

[0062] comprising the following steps:

[0063] (1) Preparation of basic copper carbonate loaded silver carbonate: a copper precursor, a silver source are added into a basic organic amine solution, heated and low concentration carbon dioxide gas is introduced, and by adjusting the concentration of the copper precursor, the concentration of the silver source, the gas flow rate, the reaction temperature and the reaction time, a basic copper carbonate loaded silver carbonate Cu x Ag y (OH)2(CO3) precipitate is obtained.

[0064] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction is completed, a reducing agent is added to the above system, and after solid-liquid separation and repeated washing, a micro-nano silver-coated copper conductive powder is obtained by drying.

[0065] The present application carries out the anti-oxidation test of the powder at 300℃, that is, the silver-coated copper powder with a mass m1 (unit: g) is placed in a muffle furnace, treated at 300℃ for 1h, and the total mass of the treated powder is measured as m2 (unit: g), and the weight gain percentage (m2-m1) / m1*100% is calculated to represent the anti-oxidation of the sample. The greater the data, the more the powder is oxidized, and the poorer the anti-oxidation performance.

[0066] The following will be described in detail in conjunction with specific examples.

[0067] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present application are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0068] Example 1

[0069] A preparation method of a micro-nano silver-coated copper conductive powder, comprising the following steps:

[0070] (1) Preparation of basic copper carbonate loaded silver carbonate: 12g of copper acetate, 100mL of 0.15mol / L silver nitrate solution is added to 900mL of 8wt% ethanolamine-triethanolamine (v:v=3:1) mixed solution, stirred and heated to 50℃, and 10vol% carbon dioxide / nitrogen mixed gas is introduced at a flow rate of 4L / min, and after 3h, a basic copper carbonate loaded silver carbonate precipitate is obtained;

[0071] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction is completed, 6mL of formic acid is added to the above system, the reaction temperature is 50℃, and ultrasonic treatment is carried out for 1h to obtain silver-coated copper powder, which is centrifuged and then placed in 50mL of deionized water, 0.15g of polyethylene glycol is added, and stirring is continued at 70℃ for 2h, and then filtered, washed with water twice, and dried at 100℃ for 3h to obtain 80-150nm thick flaky micro-nano silver-coated copper conductive powder, as shown in Figure 1 ,Figure 2 The resistivity is 2.65 x 10 -6 Ω·cm, the silver content is 15wt%, and the oxidation resistance is 2.1%.

[0072] Example 2

[0073] A method for preparing a micro-nano silver-coated copper conductive powder includes the following steps:

[0074] (1) Preparation of basic copper carbonate loaded silver carbonate: 10 g of copper hydroxide, 100 mL of 0.2 mol / L silver ammine solution, and 900 mL of 10wt% ethanolamine solution are added, heated to 30°C under stirring, and 5vol% carbon dioxide / nitrogen mixed gas is passed at a flow rate of 4 L / min, and after 2 h, a basic copper carbonate loaded silver carbonate precipitate is obtained;

[0075] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction is completed, 5 mL of 80% hydrazine hydrate solution is added to the above system, the reaction temperature is 50°C, ultrasonic stirring is performed for 1 h to obtain silver-coated copper powder, after centrifugal separation, the powder is placed in 70 mL of deionized water, 0.2 g of polyethylene glycol is added, and continuous stirring is performed at 70°C for 2 h, and then filtration and water washing are performed twice, and 100°C drying is performed for 4 h to obtain spherical micro-nano silver-coated copper conductive powder with a size of about 18-30 nm, as shown in Figure 3 , Figure 4 The resistivity is 2.18 x 10 -6 Ω·cm, the silver content is 20wt%, and the oxidation resistance is 2.0%.

[0076] Example 3

[0077] A method for preparing a micro-nano silver-coated copper conductive powder includes the following steps:

[0078] (1) Preparation of basic copper carbonate loaded silver carbonate: 15 g of copper nitrate, 100 mL of 0.2 mol / L silver ammine solution, and 900 mL of 8wt% ethanolamine solution are added, heated to 40°C under stirring, and 5vol% carbon dioxide / nitrogen mixed gas is passed at a flow rate of 5 L / min, and after 2 h, a basic copper carbonate loaded silver carbonate precipitate is obtained;

[0079] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction is completed, 8 mL of 80% hydrazine hydrate solution is added to the above system, the reaction temperature is 50°C, ultrasonic stirring is performed for 1 h to obtain silver-coated copper powder, after centrifugal separation, the powder is placed in 50 mL of deionized water, 0.18 g of polyethylene glycol is added, and continuous stirring is performed at 70°C for 2 h, and then filtration and water washing are performed, and 100°C drying is performed for 4 h to obtain spindle-shaped micro-nano silver-coated copper conductive powder with a width of 20-60 nm and a length-diameter ratio of 4-10, as shown in Figure 5 The resistivity is 2.63 x 10-6 Ωcm, silver content of 18wt%, oxidation resistance of 2.2%.

[0080] Example 4

[0081] A method for preparing a micro-nano silver-coated copper conductive powder, comprising the following steps:

[0082] (1) Preparation of basic copper carbonate loaded silver carbonate: 10 g of copper hydroxide, 100 mL of 0.15 mol / L silver ammonia solution is added to 900 mL of 6wt% ethanolamine-triethylamine (v:v=1:1) mixed solution, ultrasonic heating to 30°C and 20vol% carbon dioxide / nitrogen mixed gas is passed at a flow rate of 2L / min, after 2h, basic copper carbonate loaded silver carbonate precipitate is obtained;

[0083] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction is completed, 2.5g of glucose is added to the above system, the reaction temperature is 50°C, ultrasonic stirring for 2 hours to obtain silver-coated copper powder, after centrifugal separation, it is placed in 50 mL of deionized water, 0.2g of polyethylene glycol is added and continuously stirred at 70°C for 2h, filtered and washed with water twice, dried at 100°C for 3 hours, to obtain spherical micro-nano silver-coated copper conductive powder composed of 20-40nm small particles, as shown in Figure 6 -6 Ωcm, silver content of 15wt%, oxidation resistance of 2.3%.

[0084] Example 5

[0085] A method for preparing a micro-nano silver-coated copper conductive powder, comprising the following steps:

[0086] (1) Preparation of basic copper carbonate loaded silver carbonate: 15 g of copper nitrate, 100 mL of 0.15 mol / L silver nitrate solution is added to 900 mL of 5wt% diethanolamine solution, stirring and heating to 40°C and 5vol% carbon dioxide / nitrogen mixed gas is passed at a flow rate of 2L / min, after 4h, basic copper carbonate loaded silver carbonate precipitate is obtained;

[0087] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction is completed, 2.5g of glucose is added to the above system, the reaction temperature is 50°C, ultrasonic stirring for 2 hours to obtain silver-coated copper powder, after centrifugal separation, it is placed in 50 mL of deionized water, 0.2g of polyvinyl alcohol is added and continuously stirred at 80°C for 2h, filtered and washed with water twice, dried at 100°C for 3 hours, to obtain 32-45nm thick round cake-shaped micro-nano silver-coated copper conductive powder. The resistivity is 1.95x10 -6 Ωcm, silver content of 15wt%, oxidation resistance of 2.4%.

[0088] Example 6​

[0089] A method for preparing micro-nano silver-coated copper conductive powder, comprising the following steps:

[0090] (1) Preparation of basic copper carbonate loaded silver carbonate: 20 g of copper nitrate, 100 mL of 0.2 mol / L silver nitrate solution is added to 900 mL of 8 wt% diethanolamine-diethylamine mixed (v:v=3:1) solution, microwave heating to 50℃ and 5 vol% carbon dioxide / nitrogen mixed gas is passed at a flow rate of 4 L / min, after 4 h, basic copper carbonate loaded silver carbonate precipitate is obtained;

[0091] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction is completed, 3 g of glucose is added to the above system, the reaction temperature is 50℃, ultrasonic stirring for 2 hours to obtain silver-coated copper powder, after centrifugal separation, it is placed in 100 mL of deionized water, 0.2 g of polyvinyl alcohol is added and stirred at 80℃ for 4 h, filtered and washed twice, dried at 100℃ for 3 hours to obtain 70-100 nm spherical micro-nano silver-coated copper conductive powder. The resistivity is 2.03×10 -6 Ω·cm, the silver content is 15 wt%, and the oxidation resistance is 2.4%.

[0092] Example 7

[0093] A method for preparing micro-nano silver-coated copper conductive powder, comprising the following steps:

[0094] (1) Preparation of basic copper carbonate loaded silver carbonate: 20 g of copper nitrate, 100 mL of 0.2 mol / L silver nitrate solution is added to 900 mL of 8 wt% diethanolamine-diethylamine mixed (v:v=3:1) solution, microwave heating to 50℃ and 5 vol% carbon dioxide / nitrogen mixed gas is passed at a flow rate of 4 L / min, after 4 h, basic copper carbonate loaded silver carbonate precipitate is obtained;

[0095] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction is completed, 3 g of glucose is added to the above system, the reaction temperature is 50℃, ultrasonic stirring for 2 hours to obtain silver-coated copper powder, after centrifugal separation, it is placed in 100 mL of deionized water, 0.2 g of polyvinyl alcohol is added and stirred at 80℃ for 4 h, filtered and washed twice, dried at 100℃ for 3 hours to obtain 70-100 nm spherical micro-nano silver-coated copper conductive powder. The resistivity is 2.03×10 -6 Ω·cm, the silver content is 15 wt%, and the oxidation resistance is 2.4%.

[0096] Example 8

[0097] A method for preparing micro-nano silver-coated copper conductive powder, comprising the following steps:

[0098] (1) Preparation of basic copper carbonate loaded silver carbonate: 15 g of copper nitrate, 100 mL of 0.18 mol / L silver acetate solution was added to 900 mL of 8 wt% ethanolamine solution, heated to 50°C with stirring and 5 vol% carbon dioxide / nitrogen mixed gas was passed at a flow rate of 5 L / min, after 3 h, basic copper carbonate loaded silver carbonate precipitate was obtained;

[0099] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction, 20 g of sodium sulfite was added to the above system, the reaction temperature was 60°C, and ultrasonic stirring was carried out for 2 hours to obtain silver-coated copper powder. After centrifugal separation, it was placed in 60 mL of deionized water, 0.2 g of polyvinyl alcohol was added, and continuous stirring was carried out at 80°C for 2 h. After filtration and water washing twice, it was dried at 100°C for 3 hours to obtain 2.3-3.5 μm near-spherical micro-nano silver-coated copper conductive powder. The resistivity was 2.88×10 -6 Ω·cm, the silver content was 18 wt%, and the oxidation resistance was 2.1%.

[0100] Example 9

[0101] A method for preparing a micro-nano silver-coated copper conductive powder, comprising the following steps:

[0102] (1) Preparation of basic copper carbonate loaded silver carbonate: 15 g of copper nitrate, 100 mL of 0.18 mol / L silver acetate solution was added to 900 mL of 8 wt% ethanolamine solution, heated to 50°C with stirring and 5 vol% carbon dioxide / nitrogen mixed gas was passed at a flow rate of 5 L / min, after 3 h, basic copper carbonate loaded silver carbonate precipitate was obtained;

[0103] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction, 20 g of sodium sulfite was added to the above system, the reaction temperature was 60°C, and ultrasonic stirring was carried out for 2 hours to obtain silver-coated copper powder. After centrifugal separation, it was placed in 60 mL of deionized water, 0.2 g of polyvinyl alcohol was added, and continuous stirring was carried out at 80°C for 2 h. After filtration and water washing twice, it was dried at 100°C for 3 hours to obtain 2.3-3.5 μm near-spherical micro-nano silver-coated copper conductive powder. The resistivity was 2.88×10 -6 Ω·cm, the silver content was 18 wt%, and the oxidation resistance was 2.1%.

[0104] Example 10

[0105] A method for preparing a micro-nano silver-coated copper conductive powder, comprising the following steps:

[0106] (1) Preparation of basic copper carbonate loaded silver carbonate: 10 g of copper oxide, 100 mL of 0.15 mol / L silver acetate solution was added to 900 mL of 10 wt% ethanolamine solution, heated to 50°C with stirring and 20 vol% carbon dioxide / nitrogen mixed gas was passed at a flow rate of 5 L / min, after 2 h, basic copper carbonate loaded silver carbonate precipitate was obtained;

[0107] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction, 6 mL of formic acid was added to the above system, the reaction temperature was 50°C, and ultrasonic stirring was carried out for 2 hours to obtain silver-coated copper powder, which was centrifuged and placed in 60 mL of deionized water, 0.18 g of polyvinylpyrrolidone was added and stirred at 60°C for 2 h, filtered, washed twice with ethanol, and dried at 90°C for 3 hours to obtain 30-45 nm spherical micro-nano silver-coated copper conductive powder. The resistivity is 2.20 x 10 -6 Ω·cm, the silver content is 15 wt%, and the oxidation resistance is 2.4%.

[0108] Example 11

[0109] A method for preparing a micro-nano silver-coated copper conductive powder, comprising the following steps:

[0110] (1) Preparation of basic copper carbonate loaded silver carbonate: 10 g of copper oxide, 100 mL of 0.15 mol / L silver acetate solution was added to 900 mL of 10 wt% ethanolamine solution, heated to 50°C with stirring and 20 vol% carbon dioxide / nitrogen mixed gas was passed at a flow rate of 5 L / min, after 2 h, basic copper carbonate loaded silver carbonate precipitate was obtained;

[0111] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction, 6 mL of formic acid was added to the above system, the reaction temperature was 50°C, and ultrasonic stirring was carried out for 2 hours to obtain silver-coated copper powder, which was centrifuged and placed in 60 mL of deionized water, 0.18 g of polyvinylpyrrolidone was added and stirred at 60°C for 2 h, filtered, washed twice with ethanol, and dried at 90°C for 3 hours to obtain 30-45 nm spherical micro-nano silver-coated copper conductive powder. The resistivity is 2.20 x 10 -6 Ω·cm, the silver content is 15 wt%, and the oxidation resistance is 2.4%.

[0112] Example 12

[0113] A method for preparing a micro-nano silver-coated copper conductive powder, comprising the following steps:

[0114] (1) Preparation of basic copper carbonate loaded silver carbonate: 10 g of copper oxide, 100 mL of 0.15 mol / L silver nitrate solution were added to 900 mL of 10 wt% ethanolamine-diethanolamine-diethylamine mixed (v:v=2:2:1) solution, heated to 80°C under stirring and 10 vol% carbon dioxide / nitrogen mixed gas was passed at a flow rate of 5 L / min, after 4 h, basic copper carbonate loaded silver carbonate precipitate was obtained;

[0115] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction was completed, 6 mL of 80% hydrazine hydrate solution was added to the above system, the reaction temperature was 50°C, and ultrasonic stirring was carried out for 1 hour to obtain silver-coated copper powder. After centrifugal separation, it was placed in 60 mL of deionized water, 0.2 g of polyacrylic acid was added, and continuous stirring was carried out at 50°C for 2 h. After filtration and water washing twice, 100°C drying was carried out for 3 hours to obtain 1.6-2.3 μm spherical micro-nano silver-coated copper conductive powder. The resistivity was 2.74 x 10 -6 Ω·cm, the silver content was 15 wt%, and the oxidation resistance was 2.1%.

[0116] Comparative Example 1

[0117] A method for preparing a micro-nano silver-coated copper conductive powder, comprising the following steps:

[0118] (1) Preparation of basic copper carbonate loaded silver carbonate: 10 g of copper oxide, 100 mL of 0.15 mol / L silver nitrate solution were added to 900 mL of 10 wt% ethanolamine-diethanolamine-diethylamine mixed (v:v=2:2:1) solution, heated to 80°C under stirring and 10 vol% carbon dioxide / nitrogen mixed gas was passed at a flow rate of 5 L / min, after 4 h, basic copper carbonate loaded silver carbonate precipitate was obtained;

[0119] (2) Preparation of micro-nano silver-coated copper conductive powder: after the reaction was completed, 6 mL of 80% hydrazine hydrate solution was added to the above system, the reaction temperature was 50°C, and ultrasonic stirring was carried out for 1 hour to obtain silver-coated copper powder. After centrifugal separation, it was placed in 60 mL of deionized water, 0.2 g of polyacrylic acid was added, and continuous stirring was carried out at 50°C for 2 h. After filtration and water washing twice, 100°C drying was carried out for 3 hours to obtain 1.6-2.3 μm spherical micro-nano silver-coated copper conductive powder. The resistivity was 2.74 x 10 -6 Ω·cm, the silver content was 15 wt%, and the oxidation resistance was 2.1%.

[0120] Comparative Example 2

[0121] A method for preparing a micro-nano silver-coated copper conductive powder, comprising the following steps:

[0122] (1) Preparation of copper powder loaded with silver carbonate: 5 g of copper powder was dispersed in 200 mL of 10 g / L sodium hydroxide solution by ultrasonic, and was heated at 60 °C for 2 h. After filtration and washing, the copper powder was added to 100 mL of 0.2 mol / L silver-ammonia solution, and was added to 900 mL of 10 wt% ethanolamine solution. The mixture was heated to 30 °C with stirring, and was bubbled with 5 vol% carbon dioxide / nitrogen mixed gas at a flow rate of 4 L / min. After 2 h, copper powder loaded with silver carbonate precipitate was obtained.

[0123] (2) Preparation of micro-nano silver-coated copper conductive powder: After the reaction, 5 mL of 80% hydrazine hydrate solution was added to the above system, and the reaction temperature was 50 °C. Ultrasonic stirring was carried out for 1 h to obtain silver-coated copper powder. After centrifugal separation, the powder was placed in 70 mL of deionized water, and 0.2 g of polyethylene glycol was added. The mixture was continuously stirred at 70 °C for 2 h. After filtration and water washing twice, the mixture was dried at 100 °C for 4 h to obtain 100-150 nm spherical micro-nano silver-coated copper conductive powder. The resistivity was 3.5 x 10 -6 Ω·cm, the silver content was 15 wt%, and the oxidation resistance was 3.4%.

[0124] The above description of the embodiments is for the purpose of facilitating the understanding and use of the present application by those skilled in the art. Those skilled in the art can easily make various modifications to the embodiments, and apply the general principles described herein to other embodiments without inventive labor. Therefore, the present application is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope of the present application should be within the scope of the present application.

Claims

1. A method for preparing micro-nano silver-coated copper conductive powder, characterized in that, The precipitation process of copper precursor is dynamically controlled by taking carbon dioxide as an acid-base regulator to obtain basic copper carbonate carrier material, and the basic copper carbonate carrier material is subjected to cation exchange of silver source to obtain basic copper carbonate loaded silver carbonate precipitate, and the basic copper carbonate loaded silver carbonate precipitate is subjected to chemical reduction, solid-liquid separation, washing and drying to obtain the micro-nano silver-coated copper conductive powder.

2. The method according to claim 1, wherein the method is characterized by, The method comprises the following steps: (1) Preparation of basic copper carbonate loaded silver carbonate precipitate: copper precursor and silver source are added into an organic amine solution to obtain a mixed solution, carbon dioxide gas is introduced into the mixed solution, and a basic copper carbonate loaded silver carbonate precipitate is obtained by reaction, and the chemical reaction formula is as follows: Cu 2+ / Cu + + OH - + CO2→ Cu2(OH)2(CO3)↓; Cu2(OH)2(CO3) + Ag + → Cu x Ag y (OH)2(CO3)↓; wherein x = 1.5-2, and y = 0-1; (2) Preparation of micro-nano silver-coated copper conductive powder: a reducing agent is added into the system of step (1), and the micro-nano silver-coated copper conductive powder is obtained by solid-liquid separation, washing and drying.

3. The method according to claim 2, wherein the method is characterized by, The concentration of the copper precursor in the mixed solution in step (1) is 0.005 mol / L-1.5 mol / L; The concentration of the silver source in the mixed solution in step (1) is 0.001-1 mol / L; The mixing mode of the copper precursor, the silver source and the alkaline organic amine solution in step (1) is one or two of stirring, ultrasonic and microwave.

4. The method according to claim 2, wherein the method is characterized by, The concentration of the carbon dioxide gas in step (1) is higher than 400 ppm, the gas flow rate is 1-100 L / min, the reaction time is 0.5-24 h, and the reaction temperature is room temperature-80 ℃.

5. The method according to claim 2, wherein the method is characterized by, The organic amine in step (1) is one or a combination of several of ethanolamine, diethanolamine, triethanolamine, ethylenediamine, diethylamine, triethylamine and N-methyl ethanolamine. The mass fraction of the organic amine in the organic amine solution is 2-80 wt%.

6. The method according to claim 2, wherein the method is characterized by, The reducing agent in step (2) is one or several of hydrazine hydrate, glucose, ascorbic acid, formic acid, sodium ascorbate, potassium ascorbate, ferrous sulfate, sodium sulfite, sodium dithionite, sodium thiosulfate, sodium hypophosphite, potassium hypophosphite, diborane, sodium borohydride, hydrogen and synthetic gas, the concentration of the reducing agent is 0.01-1 mol / L, and the reduction process is realized by stirring at 30-100 ℃ for 0.1-12 h.

7. The method according to claim 1, wherein the method is characterized by, The copper precursor is one or two of copper acetate, copper hydroxide, copper nitrate, copper chloride, copper oxide, cuprous oxide, copper sulfide, cuprous sulfide, copper sulfate, cuprous sulfate and acetylacetone copper. The silver source is one of silver nitrate, silver acetate, silver ammine solution and silver sulfate.

8. The method for preparing micro / nano silver-coated copper conductive powder according to claim 1, characterized in that, After obtaining the basic copper carbonate loaded silver carbonate precipitate, the micro-nano silver-coated copper conductive powder is obtained by chemical reduction, solid-liquid separation, surface treatment, washing and drying. The solid-liquid separation mode comprises one of centrifugation, suction filtration and pressure filtration. After the solid-liquid separation, the obtained wet powder is dispersed in a solvent to obtain a 0.001-20 wt% silver-coated copper powder suspension, 0-5 wt% of a surface treatment agent is added, and continuous stirring is carried out at 30-80 ℃ for 0.01-6 h, repeated filtration and washing are carried out, and drying is carried out at 50-120 ℃ for 1-6 h to obtain the micro-nano silver-coated copper conductive powder. The surface treatment agent comprises at least one of polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone and polyacrylic acid.

9. A micro-nano silver-coated copper conductive powder, characterized in that, The micro-nano silver-coated copper conductive powder is prepared by the preparation method in any one of claims 1-8, has a particle size in the range of 10 nm-20 μm, and has a spherical, round cake, spindle or flaky shape.

10. The use of the micro-nano silver-coated copper conductive powder according to claim 9, characterized in that, The micro-nano silver-coated copper conductive powder is used in conductive ink, conductive paste, conductive adhesive and photovoltaic paste.

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