A method for preparing a silver-copper composite material by molten salt electrolysis and the silver-copper composite material

Abstract

The present invention belongs to the technical field of melt materials, and particularly relates to a method for preparing a silver-copper composite material by molten salt electrolysis and the silver-copper composite material. The method for preparing the silver-copper composite material by molten salt electrolysis of the present invention comprises the following steps: 1) providing a working anode and a working cathode, and preparing a molten salt electrolyte; the working anode is crude copper, and the working cathode is a silver electrode plate; the molten salt electrolyte is a binary molten salt system of CuCl2 and NaCl; 2) placing the working anode and the working cathode in the molten salt electrolyte for electrolysis to form a structure in which silver strips and copper strips are alternately arranged, and then processing to obtain the product. The preparation method of the present invention can electro-deposit copper on the silver electrode by consuming the copper anode, and at the same time, by adopting a molten salt electrolyte system with a special composition, the stable combination of silver and copper can be achieved. Moreover, this method has high production efficiency and low equipment cost, and the size of the silver-copper composite strip is not limited, having good application prospects in the field of melt material preparation.

Description

Technical Field

[0001] The present invention belongs to the technical field of melt materials, and particularly relates to a method for preparing a silver-copper composite material by molten salt electrolysis and the silver-copper composite material. Background Art

[0002] With the rapid development of industries such as nuclear power, new energy vehicles, photovoltaic inverters, high-voltage power transmission and transformation, and household appliances, people's requirements for the safety of circuits are getting higher and higher. To ensure the safety of equipment circuits and personnel, matching fusing devices will be set in the circuits. As a protector for short circuits and overcurrents, the fuse is one of the most commonly used protection devices. When the current exceeds the specified value, the heat generated by the fuse itself melts the fuse element, thus disconnecting the circuit. The commonly used fusing material is made of pure silver strip. However, as a precious metal, pure silver is very expensive. To reduce costs, the application market has started to use silver-copper composite materials as fusing materials. For example, Chinese patents with publication numbers CN109585235B, CN111883400B, CN207602503U, CN216928470U, and CN209454299U all use silver-copper composite strips to replace pure silver strips. This composite material can save a large amount of silver and at the same time has the fast fusing ability of pure silver strips, and the market demand is gradually increasing.

[0003] At present, the commonly used preparation methods for silver-copper composite materials include rolling composite, side inlay composite, vacuum diffusion composite (ZL201711346188.5), etc. In rolling composite, by applying a certain pressure, the silver and copper materials are deformed to a certain extent and combined. However, this method is limited by the rolling mill equipment and it is difficult to combine well for multi-layer or ultra-multi-layer composite strips. In the side inlay composite process, while the number of material layers is limited, a large amount of excess metal needs to be milled off in subsequent processing. The vacuum diffusion composite process places the materials in a vacuum or protective atmosphere environment, applies a certain load, and makes the materials react with each other at a certain temperature to achieve composite. However, this method requires expensive equipment, the size of the composite strip is limited by the furnace chamber, and the production efficiency is low.

[0004] Therefore, there is an urgent need to develop a preparation method for silver-copper composite materials with high production efficiency, low equipment cost, the size of the silver-copper composite strip is not limited, and the stable combination of silver and copper can be achieved. Summary of the Invention

[0005] To solve the above deficiencies, the main object of the present invention is to provide a method for preparing a silver-copper composite material by molten salt electrolysis, which has high production efficiency, low equipment cost, the size of the silver-copper composite strip is not limited, and the stable combination of silver and copper can be achieved.

[0006] Another object of the present invention is to provide a silver-copper composite material with high silver-copper interface bonding strength and good performance.

[0007] To achieve the above object, the method for preparing silver-copper composite material by molten salt electrolysis of the present invention adopts the following technical solution:

[0008] A method for preparing silver-copper composite material by molten salt electrolysis includes the following steps:

[0009] 1) Provide a working anode and a working cathode, and prepare a molten salt electrolyte; the working anode is crude copper, and the working cathode is a silver electrode plate; the molten salt electrolyte is a binary molten salt system of CuCl2 and NaCl;

[0010] 2) Place the working anode and the working cathode in the molten salt electrolyte for electrolysis, so that the copper ions generated by electrolysis of the working anode are deposited on the silver electrode plate of the working cathode to form a structure in which silver strips and copper strips are arranged alternately, and then process to obtain the silver-copper composite material.

[0011] The method for preparing silver-copper composite material by molten salt electrolysis of the present invention first applies the molten salt electrolysis method to the preparation of silver-copper composite material, and adopts a molten salt electrolyte with a special composition. By consuming the copper anode, copper is electrodeposited on the silver electrode to achieve the stable combination of silver and copper and improve the bonding strength. And this method has high production efficiency and low equipment cost, and the size of the silver-copper composite strip is not limited.

[0012] Furthermore, compared with the conventional aqueous solution electrolysis system, the present invention adopts a binary molten salt system of CuCl2 and NaCl, whose melting point is lower than the silver-copper eutectic temperature (779 °C). By using this molten salt system for electrolysis at a higher electrolysis temperature, the bonding strength between copper and silver in the obtained silver-copper composite material is not only the bonding force generated by electrodeposition, but also a certain degree of atomic diffusion can occur between silver and copper under high-temperature environment, thus greatly improving the interfacial bonding strength of the composite material.

[0013] Preferably, the silver electrode plate is a single-layer silver electrode plate or a multi-layer silver electrode plate; the number of layers of the multi-layer silver electrode plate ≥ 2.

[0014] Furthermore, the number of layers of the silver electrode plate is set according to the required number of silver strips in the silver-copper composite material. When the silver electrode plate is a multi-layer silver electrode plate, the interval between each layer of silver electrode plate is the same as the width of the copper strip in the silver-copper composite material. In the present invention, copper is electrodeposited on the silver electrode plate through the molten salt electrolysis process to form a structure in which silver strips and copper strips are arranged alternately. Therefore, the interval between each silver layer determines the width of the copper strip obtained by electrodeposition.

[0015] The molten salt system adopted in the present invention is a molten salt system containing copper ions. Preferably, in the molten salt electrolyte, the molar ratio of CuCl2 to NaCl is 0.7:0.3. Using the molten salt system with this composition can effectively improve the bonding strength of the silver-copper interface in the silver-copper composite material on the basis of improving the current efficiency and saving energy.

[0016] Further, the electrolysis is constant current electrolysis or constant voltage electrolysis.

[0017] Further preferably, the current of the constant current electrolysis is 100 - 200 A / m 2 ; the voltage of the constant voltage electrolysis is 1 - 1.5 V.

[0018] For the selection of the electrolysis temperature, the following principles should be followed: the electrolysis temperature should be higher than the melting temperature of the electrolyte and lower than the silver-copper eutectic temperature (779 °C). When the electrolysis temperature is lower than the silver-copper eutectic temperature, it can avoid the melting of the silver-copper composite strip; when the electrolysis temperature is higher than the melting temperature of the electrolyte, it can effectively ensure that the molten salt electrolyte is in a molten state and promote the progress of the electrolysis process. Preferably, the electrolysis temperature is 545 - 560 °C.

[0019] Based on the electrolysis process of the molten salt system, in order to ensure the quality of the silver-copper composite material and reduce the oxygen content in the copper layer, preferably, the electrolysis is carried out under the protection of an inert gas.

[0020] Further, the processing is milling and rolling the electrolyzed composite material. The milling is to mill the copper deposited on the width surface of the silver strip to ensure that the product is a strip of silver / copper appearing in sequence; the rolling is to roll the silver-copper composite material into the required thickness along the directions of the silver strip and the copper strip.

[0021] The technical solution adopted for the silver-copper composite material of the present invention is:

[0022] A silver-copper composite material is formed by arranging copper strips and silver strips in sequence, and the outermost layer is a copper strip. The silver-copper composite material is prepared by the method for preparing a silver-copper composite material by molten salt electrolysis as described above.

[0023] The size of the silver-copper composite material of the present invention is not limited, and it is convenient to realize the preparation of large-size silver-copper composite materials. Further, the number of silver strips ≥ 3.

[0024] The silver-copper composite material of the present invention deposits copper on the silver electrode by consuming the copper anode, realizing the stable combination of silver and copper. The bonding interface has high strength and is suitable for use as a melt material.

[0025] The overall beneficial effect of the present invention is:

[0026] (1) The greatest advantage of the composite material obtained by electrolysis is that its size is not restricted. By simply changing the number of layers and the size of the multi-layer silver electrodes, large-sized silver-copper composite strips (width greater than 140 mm, number of silver strips greater than 3) that are difficult to obtain by other processes can be achieved.

[0027] (2) Low-cost crude copper is selected during electrolysis, and there is no need to use the high-purity oxygen-free copper selected by the existing processes. During electrolysis, crude copper can be refined electrolytically, greatly reducing production costs. The refining principle is as follows: Impurities such as gold and silver in crude copper, whose electrical properties are more positive than copper, cannot form ions during electrolysis and exist in the form of a single substance at the bottom of the anode. While copper is refined, a large amount of precious metals can be recovered. For metals whose electrical properties are more negative than copper, they exist in the form of ions in the melt and cannot be deposited on the cathode, thus achieving the refining of crude copper.

[0028] (3) The method of preparing silver-copper composite materials by high-temperature molten salt electrolysis proposed in the present invention has significantly improved the bonding strength between silver and copper.

[0029] (4) By using the electrolysis method, the production efficiency can be significantly improved. The number of electrolytic cells can be increased according to requirements. The electrolytic cells are extremely cheap compared to the equipment required by other processes (such as vacuum furnaces, diffusion furnaces, etc.). Brief Description of the Drawings

[0030] Figure 1 The electrolysis device (left figure) adopted by the method for preparing silver-copper composite materials by molten salt electrolysis of the present invention and the schematic structural diagram of the silver electrode plate (right figure);

[0031] Figure 2 The micrograph of the bonding interface of the silver-copper composite material in Example 1 of the present invention;

[0032] Figure 3 The fracture micrograph of the bonding interface of the silver-copper composite material in Example 1 of the present invention;

[0033] Among them, Figure 1 In, the components represented by each reference numeral are as follows: 1 - electrolysis power supply interface, 2 - horizontal silver electrode plate, 3 - vertical silver electrode plate. Detailed Embodiments

[0034] In order to more clearly illustrate the technical solutions of the present invention, the implementation schemes of the present invention will be described in detail below in combination with embodiments. However, those skilled in the art should understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0035] In the following examples and comparative examples, the electrolysis device adopted by the method for preparing silver-copper composite materials by molten salt electrolysis and the schematic structural diagram of the silver electrode plate are as Figure 1 shown.

[0036] Figure 1 Among them, the copper electrode is the working anode, and the working anode is connected to the positive electrode of the power supply. The working cathode is a silver electrode plate, and the working cathode is connected to the negative electrode of the power supply. To save costs, the copper electrode can be made of crude copper. The silver electrode plate can be single-layer or multi-layer.

[0037] When the silver electrode plate is a multi-layer electrode plate, the multi-layer electrode plate is composed of an electrolytic power supply interface 1, a silver electrode horizontal plate 2, and multiple single silver electrode vertical plates 3. The single silver electrode vertical plates 3 are arranged in parallel on the silver electrode horizontal plate 2 in sequence, and the intervals between the silver electrode vertical plates 3 are equal. Among them, the function of the silver electrode horizontal plate is to connect each silver electrode vertical plate so that there is current passing through each silver electrode vertical plate; the function of the silver electrode vertical plate is that when the electrolysis process starts, there are a large number of electrons with negative charges on each silver electrode vertical plate, so that Cu 2+ will be deposited on the silver plate surface in large quantities. Therefore, the silver electrode vertical plate is not only the substrate for Cu 2+ electrodeposition, but also the partition necessary for the alternating appearance of the composite materials Ag and Cu. Among them, w1 is the width of the silver electrode vertical plate, w2 is the interval distance of the silver electrode vertical plate, that is, the width of the copper strip to be electrodeposited, h is the height of the silver electrode, and L is the thickness of the silver electrode.

[0038] In other embodiments, when the silver electrode plate is a single-layer electrode plate, the silver electrode horizontal plate is not required, and the electrolytic power supply can be directly connected to one end of the single-layer silver substrate. During electrolysis, Cu 2+ is deposited on the silver plate surface.

[0039] In the present invention, the height of the copper strip in the silver-copper composite material obtained after electrolysis is related to the insertion depth of the silver electrode plate. The insertion depth (copper strip height) of the silver electrode plate is generally controlled at 90-95% of the height of the silver electrode plate.

[0040] Example 1

[0041] The silver-copper composite material of this example is formed by arranging 4 copper strips and 3 silver strips in sequence, and the outermost layer is a copper strip. This silver-copper composite material is prepared by the following molten salt electrolysis method.

[0042] The method for preparing the silver-copper composite material by molten salt electrolysis in this example includes the following steps:

[0043] 1) Provide a working anode and a working cathode: The working anode is crude copper, and the working cathode is a silver electrode plate with a three-layer structure; the width w1 of the silver electrode plate is 10 mm, the height h is 500 mm, the thickness L is 500 mm; the distance w2 between each layer of silver electrode plates is 20 mm;

[0044] Prepare molten salt electrolyte: The molten salt electrolyte is a binary molten salt system composed of CuCl2 and NaCl, and the molar ratio of the two is CuCl2:NaCl = 0.7:0.3;

[0045] After electrolysis, the width of the copper strip in the silver-copper composite material is 20 mm, the height of the copper strip is 450 mm, and the thickness of the copper strip is 500 mm.

[0046] 2) First, melt the molten salt electrolyte into a liquid state, and then place the working anode and the working cathode in the molten salt electrolyte for electrolysis. During electrolysis, place the entire electrolysis device in a sealed device to create an inert gas (argon) atmosphere. Keep the electrolyte temperature at 550 °C during the electrolysis process, and the electrolysis time is 2 h. The electrolysis uses constant current electrolysis, and the current density is 150 A / m 2 , so that the copper ions generated by the electrolysis of the working anode are deposited on the silver electrode plate of the working cathode, forming a structure in which silver strips and copper strips are arranged alternately. Then, further mill the composite material to mill off the copper deposited on the width surface of the silver strip to ensure that the product has silver / copper strips appearing in sequence. Then, roll the silver-copper composite material along the directions of the silver strip and the copper strip to the required thickness to obtain the finished product.

[0047] Example 2

[0048] The silver-copper composite material of this example is formed by arranging 2 copper strips and 1 silver strip in sequence, and the outermost layer is a copper strip. The following molten salt electrolysis method is used for preparation.

[0049] The method for preparing a silver-copper composite material by molten salt electrolysis in this example. The prepared silver-copper composite material is composed of 2 copper strips and 1 silver strip. The preparation process includes the following steps:

[0050] 1) Provide a working anode and a working cathode: The working anode is crude copper, and the working cathode is a silver electrode plate with a single-layer structure; the width w1 of the silver electrode plate is 10 mm, the height h is 500 mm, and the thickness L is 500 mm;

[0051] Prepare molten salt electrolyte: The molten salt electrolyte is a binary molten salt system composed of CuCl2 and NaCl, and the molar ratio of the two is CuCl2:NaCl = 0.7:0.3;

[0052] In this example, since it is a single-layer silver electrode, the width of the copper strip in the silver-copper composite material obtained after electrolysis is also the thickness of the electrodeposited copper, and this thickness is related to the electrolysis time. The height of the composite strip (i.e., the electrode insertion depth) is 450 mm, and the thickness of the composite strip is 500 mm.

[0053] 2) Pre-melt the molten salt electrolyte into a liquid state, and then place the working anode and the working cathode in the molten salt electrolyte for electrolysis. During electrolysis, place the entire electrolysis device in a sealed device to create an inert gas (argon) atmosphere. Keep the electrolyte temperature at 560 °C during the electrolysis process, and the electrolysis time is 2 h. The electrolysis is carried out under constant voltage, and the electrolysis voltage is 1.5 V. During the electrolysis process, the copper ions generated by the electrolysis of the working anode are deposited on the silver electrode plate of the working cathode, forming a structure with alternating silver and copper strips. Then, further mill the composite material to mill off the copper deposited on the width surface of the silver strip, ensuring that the product has silver / copper strips appearing in sequence. Then, roll the silver-copper composite material along the directions of the silver and copper strips to the required thickness to obtain the finished product.

[0054] Comparative Example 1

[0055] This comparative example provides a method for preparing a silver-copper composite material by molten salt electrolysis. The preparation process is basically the same as that of Example 1, except that the composition of the molten salt electrolyte is different. The molten salt electrolyte of Comparative Example 1 is CuCl2, and the electrolysis temperature is 620 °C. After electrolysis, the width of the copper strip in the obtained silver-copper composite material is 20 mm, the height is 450 mm, the thickness is 500 mm, and the electrolysis time is 2 h.

[0056] Comparative Example 2

[0057] This comparative example provides a method for preparing a silver-copper composite material by molten salt electrolysis. The preparation process is basically the same as that of Example 1, except that the composition of the molten salt electrolyte is different. The molten salt electrolyte of Comparative Example 2 is a ternary electrolyte molten salt system composed of CuCl2, NaCl, and KCl, and the molar ratio of the three is CuCl2:NaCl:KCl = 0.5:0.3:0.2, and the electrolysis temperature is 430 °C. After electrolysis, the width of the copper strip in the obtained silver-copper composite material is 20 mm, the height is 450 mm, the thickness is 500 mm, and the electrolysis time is 2 h.

[0058] Comparative Example 3

[0059] This comparative example provides a method for preparing a silver-copper composite material by molten salt electrolysis. The preparation process is basically the same as that of Example 1, except that the composition of the molten salt electrolyte is different. The molten salt electrolyte of Comparative Example 3 is NaCl, and the electrolysis temperature is 800 °C. After electrolysis, the width of the copper strip in the obtained silver-copper composite material is 20 mm, the height is 450 mm, the thickness is 500 mm, and the electrolysis time is 2 h.

[0060] Comparative Example 4

[0061] This comparative example provides a method for preparing silver-copper composite materials by molten salt electrolysis. The preparation process is basically the same as that of Example 1, except that the composition of the molten salt electrolyte is different. The molten salt electrolyte of Comparative Example 4 is a binary electrolyte molten salt system composed of NaCl and KCl, and the molar ratio of the two is NaCl:KCl = 0.7:0.3. The electrolysis temperature is 700 °C. After electrolysis, the width of the copper strip in the silver-copper composite material is 20 mm, the height is 450 mm, the thickness is 500 mm, and the electrolysis time is 2 h.

[0062] Comparative Example 5

[0063] This comparative example provides a method for preparing silver-copper composite materials by aqueous solution electrolysis. The preparation process is basically the same as that of Example 1, except that the CuSO4 solution is used as the electrolyte solution instead of the molten salt electrolyte system in Example 1 for electrolysis under normal temperature conditions. The concentration of the CuSO4 solution is 1.1 mol / L. After electrolysis, the width of the copper strip in the silver-copper composite material is 20 mm, the height is 450 mm, the thickness is 500 mm, and the electrolysis time is 2 h.

[0064] Test Example 1 Current Efficiency and Preparation Efficiency Test

[0065] Taking the molten salt systems without copper ions (Comparative Examples 3 and 4) and the molten salt systems with copper ions (Comparative Example 1 and Example 1) as the test objects, the current efficiency of the silver-copper composite materials obtained after electrolysis and before milling and rolling processing was investigated. Among them, the test process of the current efficiency is: η = m1 / m 0＝ m1 / 1.186It, where η is the current efficiency, m1 is the mass of the actually electrolyzed copper (obtained by weighing), m0 is the mass of the theoretical electrolysis product, I is the current intensity (A), t is the power-on time (h), and 1.186 is the electrochemical equivalent of copper (g / (A·h)). The results are shown in Table 1.

[0066] Table 1 Current Efficiency of Silver-Copper Composite Materials Prepared by Different Molten Salt Systems

[0067] Molten salt system Molar ratio of molten salt Current efficiency / % <![CDATA[Example 1 (CuCl2:NaCl)]]> 0.7:0.3 96 <![CDATA[Comparative Example 1 (CuCl2)]]> - 95.5 Comparative example 3 (NaCl) - 90.3 Comparative example 4 (NaCl:KCl) 0.7:0.3 91

[0068] As can be seen from Table 1, the molten salt systems of Comparative Examples 3 and 4 do not contain free copper ions, and the electrolysis efficiency will decrease significantly. This is mainly because the anode crude copper contains certain impurity elements. When the impurity elements are consumed at the anode, there are no extra copper ions in the molten salt system to precipitate at the cathode, so the current efficiency is reduced. Therefore, in order to ensure the current efficiency, the molten salt system needs to contain free copper ions.

[0069] Further, the preparation efficiency of the multi-layer silver-copper composite material obtained by electrolysis in Example 1 was calculated. Through calculation, to electrolyze 4 layers of copper with the above dimensions, 45 kg of electrolytic copper was required, and the electrolysis time was 2.0 h, which was about 6 times the efficiency of preparing the silver-copper composite material of the same specification by diffusion bonding, effectively improving the production efficiency.

[0070] Test Example 2 Performance Test of Silver-Copper Composite Material

[0071] The silver-copper layer bonding strength and the thickness of the element diffusion layer of the silver-copper composite materials obtained after electrolysis in Example 1, Comparative Example 1, and Comparative Example 2 were tested. Among them, the bonding strength of different samples was detected by the tensile shear test, and the reference standard was GB / T 11363-2008 "Test Method for the Strength of Brazed Joints"; the test method for the actual element diffusion layer thickness was: measurement by elemental line scanning of a scanning electron microscope. The test results are shown in Table 2.

[0072] Table 2 Properties of Silver-Copper Composite Strips Prepared by Different Molten Salt Systems

[0073]

[0074] As can be seen from Table 2, in Comparative Example 1, a single CuCl2 was used as the molten salt system. Although the bonding strength and the thickness of the element diffusion layer of the silver-copper composite material obtained by electrolysis of the single CuCl2 molten salt were slightly lower than those of the CuCl2+NaCl mixed molten salt system in Example 1, the melting temperature of the single molten salt system was relatively high, reaching 620 °C, which would cause great energy consumption. Example 3 was a ternary molten salt system of CuCl2+NaCl+KCl, and the melting temperature of the molten salt was relatively low. However, during the electrolysis process, the element diffusion thickness between silver and copper was small, resulting in a decrease in the bonding strength and not meeting the use requirements. Comparative Example 5 used an aqueous solution electrolysis system, and the element diffusion thickness and bonding strength between silver and copper were significantly lower than those of the molten salt electrolysis system of the present invention.

[0075] Test Example 3 Oxygen Content Test

[0076] The oxygen content of the same layer of the silver-copper composite material obtained by electrolysis in Example 1 was tested, and at the same time, the oxygen content of the silver-copper composite material of the same specification obtained by the conventional rolling bonding and diffusion bonding methods in the prior art was used as a comparison. The results are shown in Table 3.

[0077] Table 3 Oxygen Content of Copper Layers of Silver-Copper Composite Materials Prepared by Different Methods

[0078] Preparation method Electrolysis method Rolling composite Diffusion composite Oxygen content in copper layer of composite material / ppm 50～75 1000～2000 110-200

[0079] As can be seen from Table 3, although high-purity oxygen-free copper is selected as the raw material for both the rolling composite method and the diffusion composite method, oxidation inevitably occurs during the subsequent processing. In the present invention, since the entire electrolysis process is in an oxygen-free environment, the oxygen content is greatly reduced.

[0080] Test Example 4 Morphology Test

[0081] The microstructure and fracture micro-morphology of the bonding interface of the silver-copper composite material obtained in Example 1 were tested by a scanning electron microscope, and the results are as Figure 2 、 3 shown.

[0082] From Figure 2 the microstructure diagram, it can be seen that the silver and copper materials are well bonded, and there is an obvious fine grain region at the interface of the silver-copper materials.

[0083] From Figure 3 the fracture morphology diagram, it can be seen that there is obvious ductile fracture at the fracture, and thus the bonding strength of the composite material can be improved.

[0084] In summary, the method for preparing silver-copper composite materials by molten salt electrolysis of the present invention can electro-deposit copper on a silver electrode by consuming a copper anode, and at the same time, by using a molten salt electrolyte system with a special composition, stable bonding of silver and copper can be achieved. Moreover, this method has high production efficiency, low equipment cost, and the size of the silver-copper composite strip is not limited, and it has great application prospects in the field of melt material preparation.

Claims

1. A method for preparing a silver-copper composite material by molten salt electrolysis, characterized in that, Comprising the following steps: 1) Provide a working anode and a working cathode, and prepare a molten salt electrolyte; the working anode is crude copper, and the working cathode is a silver electrode plate; the molten salt electrolyte is a binary molten salt system of CuCl2 and NaCl; 2) Place the working anode and the working cathode in the molten salt electrolyte for electrolysis, so that the copper ions electrolyzed from the working anode are deposited on the silver electrode plate of the working cathode to form a structure in which silver strips and copper strips are arranged alternately, and then process to obtain the silver-copper composite material; In the molten salt electrolyte described in step 1), the molar ratio of CuCl2 to NaCl is 0.7:0.3; the electrolysis in step 2) is constant current electrolysis or constant voltage electrolysis; the current of the constant current electrolysis is 100-200 A / m 2 ; The voltage of the constant voltage electrolysis is 1 to 1.5 V; the temperature of the electrolysis is 545 to 560 °C.

2. The method for preparing silver-copper composite materials by molten salt electrolysis according to claim 1, characterized in that, The silver electrode plate is a single-layer silver electrode plate or a multi-layer silver electrode plate; the number of layers of the multi-layer silver electrode plate is ≥2.

3. The method for preparing silver-copper composite material by molten salt electrolysis according to claim 2, characterized in that The number of layers of the silver electrode plate is set according to the quantity requirement of the silver strips in the silver-copper composite material; when the silver electrode plate is a multi-layer silver electrode plate, the interval between each layer of silver electrode plates is the same as the width of the copper strips in the silver-copper composite material.

4. The method for preparing a silver-copper composite material by molten salt electrolysis according to claim 1, characterized in that, The electrolysis is carried out under the protection of an inert gas.

5. The method for preparing a silver-copper composite material by molten salt electrolysis according to claim 1, wherein, The processing is to carry out milling and rolling treatment on the composite material after electrolysis.

6. A silver-copper composite material is formed by arranging copper strips and silver strips in sequence, and the outermost layer is a copper strip. It is characterized in that The silver-copper composite material is prepared by the method for preparing a silver-copper composite material by molten salt electrolysis as described in any one of claims 1 to 5.

7. The silver-copper composite material according to claim 6, wherein The number of the silver strips is ≥3.

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