A nanocrystalline copper-silver alloy current collector and a preparation method thereof

Abstract

The application provides a nanocrystalline copper-silver alloy current collector and a preparation method thereof. The content of silver atoms in the nanocrystalline copper-silver alloy current collector is 1% to 15%. The silver element in the copper-silver alloy current collector can disperse the nucleation sites of metal lithium, reduce the nucleation potential barrier and induce the uniform deposition of metal lithium.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular, the present application relates to a nanocrystalline copper-silver alloy current collector and a preparation method thereof. BACKGROUND

[0002] With the rapid rise of mobile phones, smart watches, electric vehicles and other industries, the market demand for energy storage batteries with high energy density and high safety is increasingly urgent. Among the many battery technologies, metal lithium has become the focus of research on the next generation of battery negative materials due to its impressive theoretical specific capacity (up to 3860 mAh / g) and extremely low redox electrode potential (-3.040 V standard hydrogen electrode). However, metal lithium negative electrode is prone to form lithium dendrites such as needles or dendrites during charge and discharge cycles, which not only leads to irreversible loss of battery capacity, but also can cause internal short circuit due to piercing the separator, thereby causing overheating, spontaneous combustion and other safety risks. In order to solve these problems, researchers have made many attempts from the perspectives of material structure design, battery structure design, etc., but currently the problems of low cycle efficiency, poor stability and low safety of metal lithium negative electrode cannot be perfectly solved. The growth of lithium dendrites also needs new thinking and new strategies.

[0003] The initial nucleation and growth stage of metal lithium has a crucial influence on the subsequent deposition process, which directly determines the stability of the subsequent metal lithium. Therefore, effectively controlling the nucleation and growth of metal lithium, especially ensuring uniform nucleation of metal lithium, has become the key to inhibiting the growth of lithium dendrites. However, the widely used copper foil current collector is prone to uneven enrichment during the nucleation stage of metal lithium due to its uneven surface and existing defects, which greatly increases the risk of lithium dendrite formation. Therefore, seeking a negative electrode current collector that can induce uniform nucleation of lithium metal is particularly important for the development of lithium metal negative electrode.

[0004] Currently, the negative electrode current collector that induces uniform nucleation of lithium metal is often formed by introducing alloying elements to form an alloy layer on the surface of the existing copper current collector to modify the surface of the existing copper current collector. This modification method will sacrifice the conductivity of the original current collector on the one hand, and will have the problem of poor interface bonding on the other hand. For example: patent CN108550858A discloses a copper-zinc alloy current collector for inhibiting lithium dendrites, in which a layer of copper-tin alloy is covered on the substrate material by magnetron sputtering. Patent CN114400331A discloses a negative electrode current collector preparation method that can improve the cycle stability of metal lithium, in which a layer of copper-tin alloy is covered on the surface of the copper foil by physical vapor deposition.

[0005] The above methods are all through simply covering an alloy layer on the surface of copper foil, a large number of sacrificing the original current collector conductive performance to improve the lithium dendrite growth, and there are also problems such as poor interface bonding force. Therefore, a new method is needed to induce uniform nucleation of lithium metal, and the conductivity will not be seriously lost, and also has excellent interface bonding force. SUMMARY

[0006] The present application aims to at least solve one of the technical problems in the related art. In order to inhibit the growth of lithium dendrites, improve the stability, safety and the like of the lithium metal negative electrode, and improve the strength of the current collector without seriously losing the conductivity, the present application provides a nanocrystalline copper-silver alloy current collector and a preparation method thereof. The silver element in the copper-silver alloy current collector can disperse the nucleation sites of lithium metal, reduce the nucleation barrier, and induce uniform deposition of lithium metal. The nanocrystalline copper-silver alloy current collector in the present application is realized by a direct current deposition method. In the present application, the nanocrystalline copper-silver alloy foil replaces the copper foil as the negative electrode current collector, and the content of silver atoms in the copper-silver alloy is 1% to 15%, which is realized by controlling the deposition current density or the composition of the plating solution.

[0007] In a first aspect of the present application, a nanocrystalline copper-silver alloy current collector is provided. According to an embodiment of the present application, the content of silver atoms in the nanocrystalline copper-silver alloy current collector is 1% to 15%. The silver element in the copper-silver alloy current collector can disperse the nucleation sites of lithium metal, reduce the nucleation barrier, and induce uniform deposition of lithium metal.

[0008] In another aspect of the present application, a method for preparing a nanocrystalline copper-silver alloy current collector is also provided. According to an embodiment of the present application, the method comprises:

[0009] 1) mixing copper sulfate, potassium pyrophosphate and deionized water to obtain a mixed A solution;

[0010] 2) mixing potassium iodide, potassium nitrate, silver nitrate and deionized water to obtain a mixed B solution;

[0011] 3) mixing the A solution and the B solution to obtain a C solution;

[0012] 4) mixing a refiner and the C solution to obtain a D solution,

[0013] 5) placing an anode copper plate and a cathode nickel plate into the D solution for deposition treatment to obtain the nanocrystalline copper-silver alloy current collector. The content of silver atoms in the copper-silver alloy is 1% to 15% by controlling the deposition current density or the composition of the plating solution. The silver element in the copper-silver alloy current collector can disperse the nucleation sites of lithium metal, reduce the nucleation barrier, and induce uniform deposition of lithium metal.

[0014] According to an embodiment of the present application, the method further comprises at least one of the following accessory technical features:

[0015] According to an embodiment of the present application, the mass concentration ratio of the copper sulfate and the potassium pyrophosphate in step 1) is (20-100):(60-300).

[0016] According to an embodiment of the present application, the mass concentration ratio of the copper sulfate and the potassium pyrophosphate in step 1) is (50-80):(150-240).

[0017] According to an embodiment of the present application, the mass concentration ratio of the potassium iodide, the potassium nitrate and the silver nitrate in step 2) is (150-240):(5-15):(0.15-1.5).

[0018] According to an embodiment of the present application, the dosage ratio of the A solution and the B solution in step 2) is 1:1.2.

[0019] According to an embodiment of the present application, the dosage ratio of the A solution and the B solution in step 2) is 1:1.

[0020] According to an embodiment of the present application, the temperature of the mixing process is 40-60℃.

[0021] According to an embodiment of the present application, the mixing process is carried out under stirring, and the stirring speed is 200-800rpm.

[0022] According to an embodiment of the present application, the refiner is thiourea, 2-mercaptobenzimidazole or sodium poly(dithio-dipropyl sulfone).

[0023] According to an embodiment of the present application, the deposition process is carried out using a direct current power supply.

[0024] According to an embodiment of the present application, the current density of the direct current power supply is 2-20mA / cm 2 .

[0025] According to an embodiment of the present application, the deposition process is carried out using a direct current power supply.

[0026] According to an embodiment of the present application, the anode copper plate and the cathode nickel plate are anode copper plates and cathode nickel plates which are polished, washed with water, cleaned with anhydrous ethanol and then dried.

[0027] In still another aspect of the present application, the present application further provides a battery. According to an embodiment of the present application, the battery comprises the nanocrystalline copper-silver alloy current collector as described above or prepared according to the method as described above. BRIEF DESCRIPTION OF DRAWINGS

[0028] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the following drawings of which:

[0029] Figure 1 SEM image of lithium deposition on the nanocrystalline copper-silver alloy current collector according to an embodiment of the present application. DETAILED DESCRIPTION

[0030] The embodiments described below are exemplary and are intended to be illustrative of the present application, and are not to be understood as limiting the present application.

[0031] Example 1

[0032] 1. Prepare a mixed solution A according to the following component proportions: copper sulfate 50 g / L, potassium pyrophosphate 150 g / L;

[0033] 2. Prepare a mixed solution B according to the following component proportions: potassium iodide 150 g / L, potassium nitrate 10 g / L, silver nitrate 0.34 g / L;

[0034] 3. Mix the A solution obtained in step 1 with the B solution obtained in step 2 to obtain a C solution;

[0035] 4. Dissolve 0.005 g / L thiourea in the C solution obtained in step 3 according to the above component proportions to obtain a D solution;

[0036] 5. Place the anode copper plate and cathode nickel plate, which have been polished, washed with water, cleaned with anhydrous ethanol, and dried, into the D solution obtained in step 4, and perform deposition using a direct current power supply, with a current density of 5 mA / cm2, a deposition time of 60 min, a constant temperature of 50°C, and a stirring speed of 200 rpm, to obtain a nanocrystalline copper-silver alloy current collector from the substrate.

[0037] Example 2

[0038] 1. Prepare a mixed solution A according to the following component proportions: copper sulfate 50 g / L, potassium pyrophosphate 150 g / L;

[0039] 2. Prepare a mixed solution B according to the following component proportions: potassium iodide 150 g / L, potassium nitrate 10 g / L, silver nitrate 0.68 g / L;

[0040] 3. Mix the A solution obtained in step 1 with the B solution obtained in step 2 to obtain a C solution;

[0041] 4. Dissolve 0.005 g / L thiourea in the C solution obtained in step 3 according to the above component proportions to obtain a D solution;

[0042] 5. The anode copper plate and cathode nickel plate which are polished, washed with water, cleaned with anhydrous ethanol and dried are put into the D solution obtained in step 4, deposition is carried out using a direct current power source, the current density is 5 mA / cm2, the deposition time is 60 min, the constant temperature is 50℃, the stirring speed is 200 rpm, and the nanocrystalline copper-silver alloy current collector is obtained by peeling off from the substrate.

[0043] Example 3

[0044] 1. A mixed solution A is configured according to the following component proportions: copper sulfate 50 g / L, potassium pyrophosphate 150 g / L;

[0045] 2. A mixed solution B is configured according to the following component proportions: potassium iodide 150 g / L, potassium nitrate 10 g / L, silver nitrate 1.02 g / L;

[0046] 3. The A solution obtained in step 1 is mixed with the B solution obtained in step 2 to obtain a C solution;

[0047] 4. 0.005 g / L thiourea is dissolved in the C solution obtained in step 3 according to the above component proportions to obtain a D solution;

[0048] 5. The anode copper plate and cathode nickel plate which are polished, washed with water, cleaned with anhydrous ethanol and dried are put into the D solution obtained in step 4, deposition is carried out using a direct current power source, the current density is 5 mA / cm2, the deposition time is 60 min, the constant temperature is 50℃, the stirring speed is 200 rpm, and the nanocrystalline copper-silver alloy current collector is obtained by peeling off from the substrate.

[0049] Example 4

[0050] 1. A mixed solution A is configured according to the following component proportions: copper sulfate 50 g / L, potassium pyrophosphate 150 g / L;

[0051] 2. A mixed solution B is configured according to the following component proportions: potassium iodide 150 g / L, potassium nitrate 10 g / L, silver nitrate 1.36 g / L;

[0052] 3. The A solution obtained in step 1 is mixed with the B solution obtained in step 2 to obtain a C solution;

[0053] 4. 0.005 g / L thiourea is dissolved in the C solution obtained in step 3 according to the above component proportions to obtain a D solution;

[0054] 5. The anode copper plate and cathode nickel plate which are polished, washed with water, cleaned with anhydrous ethanol and dried are put into the D solution obtained in step 4, deposition is carried out using a direct current power source, the current density is 10 mA / cm2, the deposition time is 60 min, the constant temperature is 50℃, the stirring speed is 200 rpm, and the nanocrystalline copper-silver alloy current collector is obtained by peeling off from the substrate.

[0055] Example 5

[0056] 1. Prepare mixed solution A according to the following component proportions: copper sulfate 50 g / L, potassium pyrophosphate 150 g / L;

[0057] 2. Prepare mixed solution B according to the following component proportions: potassium iodide 150 g / L, potassium nitrate 10 g / L, silver nitrate 0.34 g / L;

[0058] 3. Mix the A solution obtained in step 1 with the B solution obtained in step 2 to obtain C solution;

[0059] 4. Dissolve 0.005 g / L thiourea in the C solution obtained in step 3 according to the above component proportions to obtain D solution;

[0060] 5. Place the anode copper plate and cathode nickel plate, which have been polished, washed with water, cleaned with anhydrous ethanol and dried, into the D solution obtained in step 4, use a direct current power source for deposition, the current density is 10 mA / cm2, the deposition time is 30 min, the constant temperature is 50°C, the stirring speed is 200 rpm, and a nanocrystalline copper-silver alloy current collector is obtained by peeling off from the substrate.

[0061] Example 6

[0062] 1. Prepare mixed solution A according to the following component proportions: copper sulfate 50 g / L, potassium pyrophosphate 150 g / L;

[0063] 2. Prepare mixed solution B according to the following component proportions: potassium iodide 150 g / L, potassium nitrate 10 g / L, silver nitrate 0.34 g / L;

[0064] 3. Mix the A solution obtained in step 1 with the B solution obtained in step 2 to obtain C solution;

[0065] 4. Dissolve 0.005 g / L thiourea in the C solution obtained in step 3 according to the above component proportions to obtain D solution;

[0066] 5. Place the anode copper plate and cathode nickel plate, which have been polished, washed with water, cleaned with anhydrous ethanol and dried, into the D solution obtained in step 4, use a direct current power source for deposition, the current density is 15 mA / cm2, the deposition time is 20 min, the constant temperature is 50°C, the stirring speed is 200 rpm, and a nanocrystalline copper-silver alloy current collector is obtained by peeling off from the substrate.

[0067] Comparative Example 1

[0068] 1. Prepare mixed solution A according to the following component proportions: copper sulfate 120 g / L, copper chloride 100 g / L, concentrated sulfuric acid 60 g / L;

[0069] 2. Add 0.02 g / L of polydithiopropanesulfonic acid sodium and 0.01 g / L of sodium dodecylbenzenesulfonate to the A solution obtained in step 1 to obtain a B solution;

[0070] 3. Put the anode copper plate and the cathode stainless steel plate, which have been polished, washed with water, cleaned with anhydrous ethanol and dried, into the B solution obtained in step 2, deposit using a direct current power source, the current density is 10 mA / cm2, the deposition time is 30 min, the constant temperature is 25℃, and the stirring speed is 500 rpm, and then peel off the copper foil current collector from the substrate.

[0071] Comparative Example 2

[0072] 1. Prepare a mixed solution A according to the following component proportions: copper sulfate 120 g / L, copper chloride 100 g / L, and concentrated sulfuric acid 60 g / L;

[0073] 2. Add 0.02 g / L of polydithiopropanesulfonic acid sodium, 0.01 g / L of ethylene thiourea and 0.01 g / L of polyethylene glycol to the A solution obtained in step 1 to obtain a B solution;

[0074] 3. Put the anode copper plate and the cathode stainless steel plate, which have been polished, washed with water, cleaned with anhydrous ethanol and dried, into the B solution obtained in step 2, deposit using a direct current power source, the current density is 10 mA / cm2, the deposition time is 30 min, the constant temperature is 25℃, and the stirring speed is 500 rpm, and then peel off the copper foil current collector from the substrate.

[0075] As shown in the following table data, the nanocrystalline copper-silver alloy current collector obtained by the embodiment of the present application has higher strength and good electrical conductivity. Figure 1 As shown in the following table data, the nanocrystalline copper-silver alloy current collector obtained by the embodiment of the present application has higher strength and good electrical conductivity.

[0076] Table 1 Silver content, strength and electrical conductivity of the current collector of the embodiment and the comparative example

[0077]

[0078]

[0079] In the description of the specification, the description using the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the particular feature, structure, material or characteristic being described is included in at least one embodiment or example of the present application. The illustrative appearances of the above-mentioned terms in various places in the specification are not necessarily referred to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Furthermore, the description herein of certain examples does not necessarily exclude these features, structures, materials or characteristics from being used in other examples. Without intending to limit the scope of the application, examples of the application can be summarized as follows:

[0080] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be taken as limiting the present application, and that within the scope of the present application, those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments.

Claims

1. A method for preparing nanocrystalline copper-silver alloy current collectors, characterized in that, include: 1) Copper sulfate, potassium pyrophosphate, and deionized water are mixed to obtain solution A; 2) Potassium iodide, potassium nitrate, silver nitrate, and deionized water are mixed to obtain solution B; 3) Mix solution A with solution B to obtain solution C; 4) The refining agent is mixed with the C solution to obtain the D solution; 5) The anode copper plate and cathode nickel plate are placed in the solution D for deposition treatment to obtain the nanocrystalline copper-silver alloy current collector; The silver atom content in the nanocrystalline copper-silver alloy current collector is 1% to 15%.

2. The method according to claim 1, characterized in that, The mass concentration ratio of copper sulfate and potassium pyrophosphate in step 1) is (20-100):(60-300).

3. The method according to claim 2, characterized in that, The mass concentration ratio of copper sulfate and potassium pyrophosphate in step 1) is (50-80):(150-240).

4. The method according to claim 1, characterized in that, In step 2), the mass concentration ratio of potassium iodide, potassium nitrate and silver nitrate is (150-240): (5-15): (0.15-1.5).

5. The method according to claim 1, characterized in that, In step 2), the ratio of the amount of solution A to the amount of solution B is 1:1.

2.

6. The method according to claim 5, characterized in that, In step 2), the ratio of the amount of solution A to the amount of solution B is 1:

1.

7. The method according to claim 1, wherein the mixing temperature is 40~60℃; The mixing process is carried out under stirring at a speed of 200-800 rpm.

8. The method according to claim 1, wherein the refining agent is thiourea, 2-mercaptobenzimidazole, or sodium polydithiopropane sulfonate.

9. The method of claim 1, wherein the deposition process is performed using a DC power supply; The current density of the DC power supply is 2~20mA / cm. 2 ; The deposition treatment time is 30~120 min.

10. The method according to claim 1, wherein the anode copper plate and cathode nickel plate are anode copper plates and cathode nickel plates that have been polished, washed with water, cleaned with anhydrous ethanol, and then dried.

11. A battery, characterized in that, The battery includes a nanocrystalline copper-silver alloy current collector prepared according to any one of claims 1-10.

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