Method for preparing silver-coated copper powder with controllable morphology

Abstract

The invention provides a morphology-controllable method for preparing silver-coated copper powder. The morphology-controllable method comprises the following steps: S1, dispersing copper powder in water to obtain a copper powder suspension; s2, a plurality of parts of silver nitrate are dissolved in water, different complexing agents are added, and a plurality of parts of different silver complexing solutions are obtained; s3, respectively dissolving different reducing agents in water to obtain a plurality of parts of different reducing agent solutions; s4, in a stirring state, simultaneously dropwise adding a first silver complexing solution and a first reducing agent solution into the copper powder turbid liquid, then simultaneously dropwise adding a second silver complexing solution and a second reducing agent solution, sequentially and continuously dropwise adding until an Nth silver complexing solution and an Nth reducing agent solution are completely dropwise added, and continuously stirring and reacting; and S5, carrying out solid-liquid separation, and cleaning and drying the solid to obtain the silver-coated copper powder. According to the method, the silver deposition rate is regulated and controlled by matching complexing agents and reducing agents with different complexing capacities and reducing capacities, so that the silver-coated copper powder with different morphologies such as rough surfaces or smooth and compact surfaces can be controllably prepared.

Description

Technical Field

[0001] This invention relates to the field of metal powder materials technology, and specifically to a method for preparing silver-coated copper powder with controllable morphology. Background Technology

[0002] Silver, a widely used precious metal, plays an irreplaceable role in electronics, catalysts, and medicine due to its excellent conductivity, catalytic activity, and good biocompatibility. However, its high cost and relatively limited resources significantly restrict its large-scale industrial application. In contrast, copper, an abundant and inexpensive base metal, is an ideal alternative to silver. However, copper readily oxidizes in air, forming a copper oxide layer on its surface, which not only reduces its conductivity but also affects its material stability, thus limiting its application in related fields.

[0003] Silver-coated copper powder, a typical silver-copper bimetallic composite powder, combines the advantages of both silver and copper by coating a dense, complete silver layer onto the surface of copper powder. The core-shell structure of this material not only effectively preserves the excellent conductivity of silver but also significantly enhances the oxidation resistance and environmental stability of the copper powder. Furthermore, compared to traditional silver powder, silver-coated copper powder exhibits superior resistance to silver migration in conductive pastes, effectively overcoming conductivity failure caused by silver migration. It demonstrates promising application prospects and economic value in fields such as electronic packaging, conductive adhesives, and conductive pastes.

[0004] Currently, the most common method for preparing silver-coated copper powder is electroless plating. This method has a simple process and low equipment requirements. It mainly uses reducing agents to reduce silver ions and deposit them onto the surface of copper powder, gradually forming a dense and uniform silver coating layer. Silver salt, reducing agent, and complexing agent are the core components of the electroless plating solution: silver salt serves as the source of silver ions; the reducing agent controls the reduction rate of silver ions; and the complexing agent regulates the stability of the reaction system and the silver layer growth process by complexing silver ions. In actual preparation, the stability of the electroless plating solution has a significant impact on the quality and coating effect of the silver coating layer. Different types of complexing agents and reducing agents not only affect the electroless plating reaction but also directly determine the density, continuity, and final particle size and morphology of the silver-coated copper powder. The morphology and coating effect of the silver layer prepared by a single complexing agent and reducing agent have limitations and cannot meet the application requirements of silver-coated copper powder in different scenarios.

[0005] Therefore, there is an urgent need to develop methods for controlling the morphology of silver-coated copper powder in order to prepare materials with different morphologies and meet the application requirements of silver-coated copper powder in different scenarios. Summary of the Invention

[0006] In view of the technical problems existing in the background art, the present invention provides a method for preparing silver-coated copper powder with controllable morphology, aiming to solve the technical problems of morphological limitations and difficulty in precise control in the preparation of traditional silver-coated copper powder.

[0007] In a first aspect, the present invention provides a method for preparing silver-coated copper powder with controllable morphology, comprising the following steps: S1. Disperse copper powder in water to obtain a copper powder suspension; S2. Dissolve several portions of silver nitrate in water, and then add different complexing agents to obtain several different silver complex solutions, which are respectively denoted as the first silver complex solution to the Nth silver complex solution. S3. Dissolve different reducing agents in water to obtain several different reducing agent solutions, which are respectively denoted as the first reducing agent solution to the Nth reducing agent solution; S4. While stirring, add the first silver complex solution and the first reducing agent solution dropwise to the copper powder suspension simultaneously, then add the second silver complex solution and the second reducing agent solution dropwise simultaneously, and so on, until the Nth silver complex solution and the Nth reducing agent solution are completely added, and continue stirring the reaction; where N in the Nth silver complex solution and the Nth reducing agent solution is a natural number greater than 1; S5. After the reaction is complete, solid-liquid separation is performed. The solid is washed and dried to obtain silver-coated copper powder.

[0008] Preferably, step S1 specifically includes: Copper powder is dispersed in water, a dispersant is added, and the mixture is mechanically stirred and ultrasonically dispersed. The mixture is then heated to 30-80°C to obtain a copper powder suspension.

[0009] Preferably, the dispersant includes at least one of polyvinylpyrrolidone, polyethylene glycol, gelatin, gum arabic, and OP emulsifier; the mass of the dispersant accounts for 0.5% to 10% of the mass of the copper powder.

[0010] Preferably, in step S1, the mass concentration of copper powder in the copper powder suspension is 5~20 g / L.

[0011] Preferably, in step S2, the complexing agent includes at least two of ammonia, ethylenediaminetetraacetic acid, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, citric acid, and tartaric acid; the concentration of the complexing agent in each silver complexing solution is 0.1 mol / L to 1.0 mol / L; and the molar ratio of silver nitrate to complexing agent in each silver complexing solution is (0.25~1):1.

[0012] Preferably, in step S3, the reducing agent includes at least two of glucose, hydrazine hydrate, ascorbic acid, sodium hypophosphite, and sodium borohydride; the concentration of the reducing agent in each reducing agent solution is 0.1 mol / L to 1.0 mol / L.

[0013] Preferably, steps S2 to S4 are as follows: S2. Dissolve the first silver nitrate in water, add the first complexing agent to obtain the first silver complex solution, dissolve the second silver nitrate in water, add the second complexing agent to obtain the second silver complex solution; wherein the complexing abilities of the first complexing agent and the second complexing agent are different; S3. Dissolve the first reducing agent in water to obtain a first reducing agent solution, and dissolve the second reducing agent solution in water to obtain a second reducing agent solution; wherein the first reducing agent and the second reducing agent have different reducing abilities; S4. While stirring, add the first silver complex solution and the first reducing agent solution dropwise to the copper powder suspension simultaneously, then add the second silver complex solution and the second reducing agent solution dropwise simultaneously, and continue stirring the reaction.

[0014] Preferably, the mass of the first complexing agent accounts for 30% to 70% of the total mass of the complexing agent; the mass of the first reducing agent accounts for 30% to 70% of the total mass of the reducing agent.

[0015] Preferably, in step S4, the temperature of the stirring reaction is 30~80℃; the stirring speed is 100~1000r / min; and the stirring reaction time is 5~30min.

[0016] In a second aspect, the present invention provides a silver-coated copper powder, which is prepared by the method for preparing silver-coated copper powder with controllable morphology as described in the first aspect.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for preparing silver-coated copper powder with controllable morphology. By precisely matching complexing agents and reducing agents with different complexing and reducing abilities and adding them dropwise in succession, the silver deposition reaction rate can be precisely controlled, thereby controlling the preparation of silver-coated copper powder with different morphologies, such as rough or smooth and dense surfaces. This invention avoids the limitations of traditional methods that involve mixing multiple complexing agents or reducing agents in a single batch, which cannot finely control the morphology. It achieves controllable surface morphology and customized functionality of silver-coated copper powder, combining process simplicity, material functionality, and application adaptability, demonstrating excellent applicability potential in multiple fields such as conductive pastes and catalysis. Attached Figure Description

[0018] Figure 1 This is a SEM image of the silver-coated copper powder prepared in Example 1 of the present invention; Figure 2 This is a SEM image of the silver-coated copper powder prepared in Example 2 of the present invention; Figure 3 This is a SEM image of the silver-coated copper powder prepared in Example 3 of the present invention. Detailed Implementation

[0019] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0020] To address the limitations and difficulty in precise control of morphology in traditional silver-coated copper powder preparation, this invention provides a method for preparing silver-coated copper powder with controllable morphology. By precisely matching complexing agents and reducing agents with different complexing and reducing abilities, and performing relay droplet addition for reduction, the silver deposition reaction rate can be precisely controlled, thereby controlling the preparation of silver-coated copper powder with different morphologies such as rough or smooth and dense surfaces.

[0021] In a first aspect, embodiments of the present invention provide a method for preparing silver-coated copper powder with controllable morphology, comprising the following steps: S1. Disperse copper powder in water to obtain a copper powder suspension; S2. Dissolve several portions of silver nitrate in water, and then add different complexing agents to obtain several different silver complex solutions, which are respectively denoted as the first silver complex solution to the Nth silver complex solution. S3. Dissolve different reducing agents in water to obtain several different reducing agent solutions, which are respectively denoted as the first reducing agent solution to the Nth reducing agent solution; S4. While stirring, add the first silver complex solution and the first reducing agent solution dropwise to the copper powder suspension simultaneously, then add the second silver complex solution and the second reducing agent solution dropwise simultaneously, and so on, until the Nth silver complex solution and the Nth reducing agent solution are completely added, and continue stirring the reaction; where N in the Nth silver complex solution and the Nth reducing agent solution is a natural number greater than 1; S5. After the reaction is complete, solid-liquid separation is performed. The solid is washed and dried to obtain silver-coated copper powder.

[0022] In the technical solution of this invention, different complexing agents and reducing agents have different effects on the reaction rate regulation. Complexing agents with strong complexing ability slow down the release rate of silver ions, while complexing agents with weak complexing ability can accelerate the release of silver ions, thereby increasing the deposition rate. Similarly, reducing agents with strong reducing ability can quickly reduce silver ions to metallic silver, while reducing agents with weak reducing ability make the reaction more moderate. Through this differentiated combination design, the silver layer growth process can be gradually controlled, ultimately forming silver-coated copper powder with a specific morphology. The relay drop-addition method at different stages further enhances the precision of morphology control. For example, using a strong complexing agent and a weak reducing agent in the initial stage results in a slow silver deposition rate, which helps form a uniform and dense base silver layer. Using a weak complexing agent and a strong reducing agent in subsequent stages accelerates the silver deposition rate, allowing for the construction of a rough or specially structured outer layer on top of the base silver layer. Conversely, using a weak complexing agent and a weak reducing agent in the initial stage allows for faster silver ion release but a slower reduction rate, forming a rougher initial silver layer. Subsequent stages using a combination of strong complexing agents and strong reducing agents slow down the silver deposition rate and ensure uniform deposition, thereby optimizing the density and surface smoothness of the silver layer. This flexible control method can meet the specific morphological requirements of silver-coated copper powder in different application scenarios.

[0023] Furthermore, in some embodiments, step S1 specifically includes: Copper powder is dispersed in water, a dispersant is added, and the mixture is mechanically stirred and ultrasonically dispersed. The mixture is then heated to 30-80°C to obtain a copper powder suspension.

[0024] Furthermore, in some embodiments, the dispersant includes at least one of polyvinylpyrrolidone, polyethylene glycol, gelatin, gum arabic, and OP emulsifier; the mass of the dispersant accounts for 0.5% to 10% of the mass of the copper powder.

[0025] In the technical solution of this invention embodiment, the addition of dispersant can effectively prevent copper powder from agglomerating in water and improve the dispersion uniformity of copper powder in suspension, thereby providing a basis for the uniform deposition of subsequent silver layer.

[0026] Furthermore, in some embodiments, the mechanical stirring time is 10-40 min, and the mechanical stirring speed is 100-1000 r / min.

[0027] Furthermore, in some embodiments, in step S1, the mass concentration of copper powder in the copper powder suspension is 5~20 g / L.

[0028] Furthermore, in some embodiments, in step S2, the complexing agent includes at least two of ammonia, ethylenediaminetetraacetic acid, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, citric acid, and tartaric acid.

[0029] In the technical solution of this invention embodiment, complexing agents with different complexing abilities can be selected in stages according to the target morphology requirements of silver-coated copper powder, so as to control the silver deposition rate and thus control the morphology.

[0030] Furthermore, in some embodiments, in step S2, the concentration of the complexing agent in each silver complex solution is 0.1 mol / L to 1.0 mol / L; the molar ratio of silver nitrate to complexing agent in each silver complex solution is (0.25~1):1.

[0031] Furthermore, in some embodiments, in step S3, the reducing agent includes at least two of glucose, hydrazine hydrate, ascorbic acid, sodium hypophosphite, and sodium borohydride.

[0032] In the technical solution of this invention embodiment, reducing agents with different reducing abilities can be selected in stages according to the target morphology requirements of silver-coated copper powder, so as to control the silver deposition rate and thus control the morphology.

[0033] Furthermore, in some embodiments, in step S3, the concentration of the reducing agent in each reducing agent solution is 0.1 mol / L to 1.0 mol / L.

[0034] Furthermore, in some embodiments, steps S2 to S4 specifically include: S2. Dissolve the first silver nitrate in water, add the first complexing agent to obtain the first silver complex solution, dissolve the second silver nitrate in water, add the second complexing agent to obtain the second silver complex solution; wherein the complexing abilities of the first complexing agent and the second complexing agent are different; S3. Dissolve the first reducing agent in water to obtain a first reducing agent solution, and dissolve the second reducing agent solution in water to obtain a second reducing agent solution; wherein the first reducing agent and the second reducing agent have different reducing abilities; S4. While stirring, add the first silver complex solution and the first reducing agent solution dropwise to the copper powder suspension simultaneously, then add the second silver complex solution and the second reducing agent solution dropwise simultaneously, and continue stirring the reaction.

[0035] Furthermore, in some embodiments, the mass of the first complexing agent accounts for 30% to 70% of the total mass of the complexing agent; the mass of the first reducing agent accounts for 30% to 70% of the total mass of the reducing agent.

[0036] In the technical solution of this invention, by adjusting the mass ratio of the first complexing agent to the second complexing agent, and the mass ratio of the first reducing agent to the second reducing agent, the dynamic balance of the reaction system can be further fine-tuned to ensure the stability and controllability of the silver layer growth process. For example, when it is necessary to prepare silver-coated copper powder with a smooth and dense surface, the ratio of strong complexing agent to weak reducing agent can be appropriately increased to slow down the release and reduction rate of silver ions and promote uniform deposition of the silver layer; while when it is necessary to prepare silver-coated copper powder with a rough surface or a special structure, the ratio of weak complexing agent to strong reducing agent can be increased to accelerate the silver deposition rate and form the desired rough outer layer or special morphology.

[0037] Furthermore, in some embodiments, in step S4, the temperature of the stirring reaction is 30~80℃; the stirring speed is 100~1000r / min; and the stirring reaction continues for 5~30min.

[0038] Secondly, embodiments of the present invention provide a silver-coated copper powder, which is prepared by the method for preparing morphology-controllable silver-coated copper powder as described in the first aspect.

[0039] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0040] I. Preparation Method Example 1 A method for preparing silver-coated copper powder with controllable morphology, the specific steps of which are as follows: S1. Weigh 10g of copper powder and add it to 1000mL of deionized water, then add 1.0g of PVP, ultrasonically disperse and mechanically stir for 15min at a stirring rate of 200r / min, and heat in a water bath to 40℃ to obtain a copper powder suspension; S2. Weigh 4.2g of silver nitrate and dissolve it in 120mL of deionized water. Add 7.2g of triethylenetetramine to the dissolved silver nitrate solution to form a silver complex solution ①. S3. Weigh 4.2g of silver nitrate and dissolve it in 120mL of deionized water. Add 6.93g of ammonia to the dissolved silver nitrate solution to form a silver complex solution ②. S4. Weigh 2.2g of glucose, add 50mL of deionized water, and dissolve to form a reducing agent solution ①; S5. Weigh 2.2g of ascorbic acid, add 50mL of deionized water, and dissolve to form a reducing agent solution ②; S6. Simultaneously add silver complex solution ① and reducing agent solution ① to a uniformly dispersed copper powder suspension. After the addition of silver complex solution ① and reducing agent solution ① is complete, simultaneously add silver complex solution ② and reducing agent solution ②. After all solutions have been added, continue stirring for 5 minutes, then perform solid-liquid separation. Wash and dry the solid obtained from the reaction to obtain the following... Figure 1 The image shows a rough surface of silver-coated copper powder.

[0041] In this embodiment, triethylenetetramine has a stronger complexing ability than ammonia, and ascorbic acid has a stronger reducing ability than glucose. When silver complex solution ① and reducing agent solution ① are added dropwise, due to the stronger complexing effect of triethylenetetramine, silver ions are not easily released, and glucose has a weaker reducing ability, resulting in a slower silver deposition rate and the formation of a relatively dense initial silver layer. When silver complex solution ② and reducing agent solution ② are added dropwise, the complexing ability of ammonia weakens, and the reducing ability of ascorbic acid is stronger, so the release rate of silver ions increases, the reduction reaction rate accelerates, and the resulting silver layer is rougher, thus obtaining silver-coated copper powder with a rough surface; it has a large specific surface area and is suitable for use in the catalytic field.

[0042] Example 2 A method for preparing silver-coated copper powder with controllable morphology, the specific steps of which are as follows: S1. Weigh 30g of copper powder and add it to 3000mL of deionized water. Then add 3g of PVP, ultrasonically disperse and mechanically stir for 15min at a stirring rate of 400r / min, and heat in a water bath to 50℃. S2. Weigh 10g of silver nitrate and dissolve it in 250mL of deionized water. Add 4g of ethylenediamine to the dissolved silver nitrate solution to form a silver complex solution ①. S3. Weigh 10g of silver nitrate and dissolve it in 250mL of deionized water. Add 16.5g of ammonia to the dissolved silver nitrate solution to form a silver complex solution ②. S4. Weigh 5g of ascorbic acid, add 210mL of deionized water, and dissolve to form a reducing agent solution ①. S5. Weigh 5g of glucose, add 210mL of deionized water, and dissolve to form a reducing agent solution ②. S6. Simultaneously add silver complex solution ① and reducing agent solution ① to a uniformly dispersed copper powder suspension. After the addition of silver complex solution ① and reducing agent solution ① is complete, simultaneously add silver complex solution ② and reducing agent solution ②. After all solutions have been added, continue stirring for 5 minutes, then perform solid-liquid separation. Wash and dry the solid obtained from the reaction to obtain the following... Figure 2 The surface shown contains silver-coated copper powder with raised silver particles.

[0043] In this embodiment, ethylenediamine has a stronger complexing ability than ammonia, and ascorbic acid has a stronger reducing ability than glucose. When silver complex solution ① and reducing agent solution ① are added, the stronger complexing effect of ethylenediamine and the stronger reducing ability of ascorbic acid result in a moderate silver deposition rate, forming a relatively dense initial silver layer. With the addition of silver complex solution ② and reducing agent solution ②, the weaker complexing effect of ammonia accelerates the release rate of silver ions, while the relatively weaker reducing ability of glucose leads to an uneven silver deposition process, resulting in a raised silver particle morphology on the surface of the silver-coated copper powder. This unique surface structure gives the material better adhesion, making it suitable for use in the encapsulation field.

[0044] Example 3 A method for preparing silver-coated copper powder with controllable morphology, the specific steps of which are as follows: S1. Weigh 10g of copper powder and add it to 1000mL of deionized water, then add 1g of PVP, ultrasonically disperse and mechanically stir for 15min at a stirring rate of 300r / min, and heat in a water bath to 30℃. S2. Weigh 4g of silver nitrate and dissolve it in 100mL of deionized water. Add 2g of ethylenediamine to the dissolved silver nitrate solution to form a silver complex solution ①. S3. Weigh 4g of silver nitrate and dissolve it in 100mL of deionized water. Add 7.0g of triethylenetetramine to the dissolved silver nitrate solution to form a silver complex solution ②. S4. Weigh 2.2g of ascorbic acid, add 50mL of deionized water, and dissolve to form a reducing agent solution ①; S5. Weigh 1g of hydrazine hydrate, add 50mL of deionized water, and dilute to form a reducing agent solution ②. S6. Simultaneously add silver complex solution ① and reducing agent solution ① to a uniformly dispersed copper powder suspension. After the addition of silver complex solution ① and reducing agent solution ① is complete, simultaneously add silver complex solution ② and reducing agent solution ②. After all solutions have been added, continue stirring for 5 minutes, then perform solid-liquid separation. Wash and dry the solid obtained from the reaction to obtain the following... Figure 3 The silver layer shown is a smooth and uniform silver-coated copper powder.

[0045] In this embodiment, the complexing ability of ethylenediamine is relatively weaker than that of triethylenetetramine, and the reducing ability of ascorbic acid is relatively weaker than that of hydrazine hydrate. When silver complex solution ① and reducing agent solution ① are added, due to the relatively weak complexing effect of ethylenediamine and the relatively weak reducing ability of ascorbic acid, silver ions are released relatively quickly but the reduction rate is slow, resulting in a relatively rough initial silver layer. With the addition of silver complex solution ② and reducing agent solution ②, the strong complexing effect of triethylenetetramine inhibits the release rate of silver ions to some extent, while the reducing ability of hydrazine hydrate is enhanced, thus making the growth process of the silver layer more stable and gradually modifying the rough initial silver layer into a smooth and uniform silver-coated copper powder. This type of silver-coated copper powder has low surface roughness and high density, making it suitable for use in conductive pastes.

[0046] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for preparing silver-coated copper powder with controllable morphology, characterized in that, Includes the following steps: S1. Disperse copper powder in water to obtain a copper powder suspension; S2. Dissolve several portions of silver nitrate in water, and then add different complexing agents to obtain several different silver complex solutions, which are respectively denoted as the first silver complex solution to the Nth silver complex solution. S3. Dissolve different reducing agents in water to obtain several different reducing agent solutions, which are respectively denoted as the first reducing agent solution to the Nth reducing agent solution; S4. While stirring, add the first silver complex solution and the first reducing agent solution dropwise to the copper powder suspension simultaneously, then add the second silver complex solution and the second reducing agent solution dropwise simultaneously, and so on, until the Nth silver complex solution and the Nth reducing agent solution are completely added, and continue stirring the reaction; where N in the Nth silver complex solution and the Nth reducing agent solution is a natural number greater than 1; S5. After the reaction is complete, solid-liquid separation is performed. The solid is washed and dried to obtain silver-coated copper powder.

2. The method for preparing silver-coated copper powder with controllable morphology according to claim 1, characterized in that, Step S1 specifically involves: Copper powder is dispersed in water, a dispersant is added, and the mixture is mechanically stirred and ultrasonically dispersed. The mixture is then heated to 30-80°C to obtain a copper powder suspension.

3. The method for preparing silver-coated copper powder with controllable morphology according to claim 2, characterized in that, The dispersant includes at least one of polyvinylpyrrolidone, polyethylene glycol, gelatin, gum arabic, and OP emulsifier; And / or, the mass of the dispersant accounts for 0.5% to 10% of the mass of the copper powder.

4. The method for preparing silver-coated copper powder with controllable morphology according to claim 1, characterized in that, In step S1, the mass concentration of copper powder in the copper powder suspension is 5~20g / L.

5. The method for preparing silver-coated copper powder with controllable morphology according to claim 1, characterized in that, In step S2, the complexing agent includes at least two of ammonia, ethylenediaminetetraacetic acid, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, citric acid, and tartaric acid. And / or, the concentration of the complexing agent in each of the silver complex solutions is 0.1 mol / L to 1.0 mol / L; And / or, in each of the silver complex solutions, the molar ratio of silver nitrate to complexing agent is (0.25~1):

1.

6. The method for preparing silver-coated copper powder with controllable morphology according to claim 1, characterized in that, In step S3, the reducing agent includes at least two of glucose, hydrazine hydrate, ascorbic acid, sodium hypophosphite, and sodium borohydride. And / or, the concentration of the reducing agent in each of the reducing agent solutions is 0.1 mol / L to 1.0 mol / L.

7. The method for preparing silver-coated copper powder with controllable morphology according to claim 1, characterized in that, The specific steps S2~S4 are as follows: S2. Dissolve the first silver nitrate in water, add the first complexing agent to obtain the first silver complex solution, dissolve the second silver nitrate in water, add the second complexing agent to obtain the second silver complex solution; wherein the complexing abilities of the first complexing agent and the second complexing agent are different; S3. Dissolve the first reducing agent in water to obtain a first reducing agent solution, and dissolve the second reducing agent solution in water to obtain a second reducing agent solution; wherein the first reducing agent and the second reducing agent have different reducing abilities; S4. While stirring, the first silver complex solution and the first reducing agent solution are simultaneously added dropwise to the copper powder suspension, followed by the second silver complex solution and the second reducing agent solution, and the reaction is continued with stirring.

8. The method for preparing silver-coated copper powder with controllable morphology according to claim 7, characterized in that, The first complexing agent accounts for 30% to 70% of the total mass of the complexing agent; And / or, the mass of the first reducing agent accounts for 30% to 70% of the total reducing agent.

9. The method for preparing silver-coated copper powder with controllable morphology according to claim 1, characterized in that, In step S4, the temperature of the stirring reaction is 30~80℃; And / or, the stirring speed is 100~1000 r / min; And / or, the stirring reaction is continued for 5 to 30 minutes.

10. A silver-coated copper powder, characterized in that, It is prepared by the method for morphology controllable preparation of silver-coated copper powder as described in any one of claims 1 to 9.

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