Preparation method and application of lithium-philic composite copper current collector

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a preparation method and application of a lithium-philic composite copper current collector. The preparation method comprises the following steps: 1, immersing a copper current collector into an acid solution, and removing an oxide film on the surface of the copper current collector; 2, depositing a lithium-loving modification layer on the surface of the copper current collector by adopting a physical deposition method or an electrochemical deposition method to obtain a lithium-loving composite copper current collector; wherein the lithium-philic modification layer is made of a metal film material with high reaction activity with metal lithium. Aiming at the problem of poor affinity of the copper current collector and the metal lithium negative electrode, the preparation method provided by the invention is simple and easy to operate, low in preparation cost, capable of effectively improving the affinity of the copper foil to the lithium metal negative electrode and preventing the problem of lithium stripping in the assembly process, and suitable for large-scale surface treatment of the copper current collector.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and particularly relates to a preparation method and application of a lithiumophilic composite copper current collector. Background Art

[0002] With the rapid development of the global new energy vehicle industry, traditional lithium-ion batteries can no longer meet the market's demand for high-energy-density and low-cost energy storage devices. Lithium metal anodes are regarded as one of the most promising energy storage systems due to their extremely low electrode potential and extremely high theoretical capacity. However, lithium metal anodes are prone to serious side reactions and dendrite growth, which can lead to rapid capacity decay of lithium-ion batteries and even cause safety problems such as internal short circuits and thermal runaway. To address these challenges, methods such as the development of functional current collectors, battery interface regulation, and the construction of lithiumophilic materials can effectively improve the cycling stability of lithium-ion batteries. Among them, the development of functional current collectors has great commercial value, and copper foil current collectors, with excellent electrical conductivity and strong lithiumophilic properties, have become an indispensable component in lithium metal batteries, and their performance directly affects the stability and safety of the batteries.

[0003] The existing invention with the application number CN202311709934.8 discloses a preparation process of a composite copper foil, including the following steps: S1: Spraying an alcohol solution of a zinc salt on a polymer-based film and performing heat treatment to obtain a composite film; S2: Immersing the composite film in a polyol solution containing a noble metal salt and a stabilizer to reduce noble metal ions to noble metal nanoparticles, and then cleaning to obtain a composite film; S3: Immersing the composite film in an alkaline electroless copper plating solution for copper plating to obtain the composite copper foil.

[0004] The above-mentioned existing technology has the following defects: The above method uses a spraying and heating process, which has low equipment costs, but the process is cumbersome, it is difficult to guarantee the quality of the current collector, and the lithiumophilic property of the copper foil is difficult to guarantee, which may cause short circuit problems due to the shedding of metallic lithium during the assembly process.

[0005] Based on this, the present invention aims to provide a preparation method and application of a lithiumophilic composite copper current collector, which is simple and easy to operate, has low preparation costs, can effectively improve the affinity of copper foil for lithium metal anodes, and prevent lithium peeling problems during the assembly process. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method and application of a lithiumophilic composite copper current collector. The preparation process is simple, highly operable, and can solve the short circuit problem caused by lithium peeling during the assembly process of metal lithium battery packs.

[0007] According to the first aspect of the present invention, the present invention provides a preparation method of a lithiumophilic composite copper current collector, and the preparation method includes the following steps:

[0008] 1. Immerse the copper current collector in an acidic solution to remove the oxide film on the surface.

[0009] 2. Deposit a lithium - affinity modification layer on the surface of the copper current collector by physical deposition or electrochemical deposition to obtain a lithium - affinity composite copper current collector.

[0010] Among them, the lithium - affinity modification layer is a metal thin - film material with high reactivity with metallic lithium.

[0011] The present invention aims at the problem of poor affinity between the copper current collector and the metallic lithium anode. A lithium - affinity modification layer is deposited on the surface of the copper current collector by physical deposition or electrochemical deposition, thereby obtaining a lithium - affinity composite copper current collector with a lithium - affinity modification layer. The lithium - affinity modification layer is a metal thin - film material with high reactivity with metallic lithium. Therefore, the presence of the lithium - affinity modification layer can improve the lithium - affinity of the copper current collector, thereby enhancing the affinity between the metallic lithium anode and the copper current collector, reducing the risk of battery short - circuit during the assembly process. Compared with the prior art for preparing composite copper current collectors, the preparation method of the present invention deposits the lithium - affinity modification layer by physical deposition or electrochemical deposition, having the advantages of simple preparation process, low equipment cost, and being suitable for large - scale surface treatment of copper current collectors.

[0012] In some embodiments of the present invention, depositing a lithium - affinity modification layer on the surface of the copper current collector by physical deposition includes the following steps: plating a lithium - affinity metal on the surface of the copper current collector by physical deposition to deposit a lithium - affinity modification layer on the surface of the copper current collector; among them, the lithium - affinity metal is one of tin, silver, zinc, and aluminum; the physical deposition method is one of magnetron sputtering, atomic layer deposition, and thermal evaporation.

[0013] By adopting the above - mentioned technical solution, the lithium - affinity metals such as tin, silver, zinc, and aluminum are converted into a vapor state or an ionized state by physical deposition methods such as thermal evaporation, magnetron sputtering, or atomic layer deposition, and then condensed on the surface of the copper current collector to form a thin film, obtaining a copper current collector with a lithium - affinity metal thin film. The surface of the lithium - affinity metal thin film usually has a low gel energy, making it easy for lithium ions to combine with it. Therefore, this copper current collector can effectively improve the affinity of the copper foil for the lithium metal anode and prevent the problem of lithium flaking during the assembly process.

[0014] In some embodiments of the present invention, the deposition time of the physical deposition method is 1 - 60 min, and the deposition vacuum degree is 0.001 - 1 Pa. Specifically, the deposition time of the physical deposition method can be 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or a range composed of any two of the above values, not limited to the listed values, and other unlisted values within this numerical range are equally applicable. Specifically, the deposition vacuum degree is 0.001 Pa, 0.005 Pa, 0.01 Pa, 0.05 Pa, 0.1 Pa, 0.5 Pa, 0.7 Pa, 0.85 Pa, 0.95 Pa, 1 Pa, or a range composed of any two of the above values, not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0015] By adopting the above technical solution, setting the deposition time and deposition vacuum degree of the physical deposition method within the corresponding ranges can further enable the prepared lithiumophilic modification layer to firmly bond the lithium metal anode to the copper current collector. During the assembly of the lithium metal battery, the lithium metal is not easily peeled off from the copper current collector.

[0016] In some embodiments of the present invention, depositing a lithiumophilic modification layer on the surface of the copper current collector by electro - chemical deposition method includes the following steps: providing an electroplating solution with a certain concentration, placing the lithiumophilic metal to be deposited on the anode side, and using the copper current collector as the substrate and placing it on the cathode side; electro - chemically depositing a lithiumophilic modification layer on the surface of the copper current collector on the cathode side at a certain current density.

[0017] By adopting the above technical solution, by using an electrolytic cell containing a suitable electroplating solution, placing the copper current collector and the lithiumophilic metal to be deposited on the anode and cathode of the electrolytic cell respectively; depositing a lithiumophilic metal thin film on the surface of the copper current collector on the cathode side at a certain current density to obtain a copper current collector with a lithiumophilic metal thin film. Due to the presence of the lithiumophilic metal thin film, the problem of poor affinity between the copper current collector and the lithium metal anode can be effectively alleviated, and the short - circuit risk caused by lithium peeling during the assembly of the lithium metal battery can be reduced.

[0018] In some embodiments of the present invention, the concentration of the electroplating solution is 0.1 - 1 M; the current density is 0.1 - 10 mA / cm 2, the electroplating time is 1 - 120 min. Specifically, the concentration of the electroplating solution can be 0.1 M, 0.15 M, 0.2 M, 0.25 M, 0.4 M, 0.45 M, 0.5 M, 0.7 M, 0.8 M, 1 M or a range composed of any two of the above values. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable. Specifically, the current density can be 0.1 mA / cm 2 , 0.5 mA / cm 2 , 1 mA / cm 2 , 2 mA / cm 2 , 2.5 mA / cm 2 , 3 mA / cm 2 , 5 mA / cm 2 , 7 mA / cm 2 , 8 mA / cm 2 , 8.5 mA / cm 2 , 9 mA / cm 2 , 10 mA / cm 2 or a range composed of any two of the above values. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable. Specifically, the electroplating time can be 1 min, 2 min, 5 min, 10 min, 15 min, 20 min, 30 min, 35 min, 40 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, 105 min, 110 min, 115 min, 120 min or a range composed of any two of the above values. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0019] By adopting the above technical solution, the deposition rate and film uniformity are coordinated by controlling the concentration of the electroplating solution. If the concentration of the electroplating solution is too low, the film deposition rate is too slow; if the concentration of the electroplating solution is too high, the film uniformity is insufficient. Therefore, in this application, the concentration of the electroplating solution is selected to be between 0.1 - 1 M. At the same time, the thickness of the lithiumophilic metal film can be controlled by controlling the current density and the electroplating time, and the thickness range is between 0.05 - 10 μm.

[0020] In some embodiments of the present invention, the lithiumophilic metal is one of magnesium, zinc, indium, and tin; the electroplating solution is one or several of magnesium sulfate, magnesium chloride, magnesium nitrate, zinc sulfate, zinc nitrate, zinc chloride, indium chloride, and tin chloride.

[0021] By adopting the above technical solution, a lithiophilic metal such as magnesium, zinc, indium, or tin is placed on the anode side of the electrolytic cell. During electrolysis, the lithiophilic metal dissolves and deposits on the surface of the copper current collector on the cathode side to form a layer of lithiophilic metal film, and then a lithiophilic composite copper current collector is obtained.

[0022] In some embodiments of the present invention, the copper current collector is one of copper foil, copper foam, and porous copper; and / or, the acidic solution is one or more of dilute hydrochloric acid, dilute nitric acid, and dilute sulfuric acid.

[0023] By adopting the above technical solution, the copper foil current collector is one of the most commonly used copper current collectors in lithium-ion batteries; copper foam is a three-dimensional network material with characteristics such as light weight, high strength, and high specific surface area; porous copper is a copper material with a highly porous structure, and its porosity can reach more than 90%; each of the above materials has its unique advantages and application scenarios. Selecting a suitable copper current collector is of great significance for improving battery performance and reducing costs.

[0024] According to the second aspect of the present invention, the present invention also provides a negative electrode of a lithium metal battery. The lithiophilic composite copper current collector obtained by the above preparation method is bonded to metallic lithium and heated. After heat treatment for a certain time, a negative electrode of a lithium metal battery is obtained.

[0025] By adopting the above technical solution, the lithiophilic composite copper current collector is bonded to metallic lithium and heated. By strengthening the interfacial affinity through interfacial alloying and the alloy reaction between the lithiophilic modification layer and metallic lithium, the lithiophilicity of the copper current collector can be improved, thereby enhancing the affinity between the metallic lithium negative electrode and the copper current collector and reducing the risk of battery short circuit during the assembly process.

[0026] In some embodiments of the present invention, the conditions for the heat treatment are: the heating temperature is 181 - 400 °C, and the heating time is 1 - 120 min. Specifically, the heating temperature can be 181 °C, 182 °C, 200 °C, 220 °C, 260 °C, 300 °C, 330 °C, 350 °C, 380 °C, 400 °C or a range composed of any two of the above values, not limited to the listed values, and other unlisted values within this numerical range are equally applicable. Specifically, the heating time can be 1 min, 10 min, 20 min, 30 min, 50 min, 60 min, 65 min, 80 min, 90 min, 120 min or a range composed of any two of the above values, not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0027] By adopting the above technical solution, the heating temperature and heating time are controlled within the above ranges, and the prepared lithiumophilic modification layer can firmly bond the lithium metal anode to the copper current collector. During the assembly of the lithium metal battery, the lithium metal is not easily peeled off from the copper current collector.

[0028] According to the third aspect of the present invention, the present invention also provides a battery, including a positive electrode, a negative electrode and an electrolyte, and the negative electrode is selected from the lithium metal battery negative electrode as described in the second aspect of the present invention.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) In the present invention, a lithiumophilic modification layer is deposited on the surface of the copper current collector by physical deposition or electrochemical deposition, so as to obtain a lithiumophilic composite copper current collector with a lithiumophilic modification layer. The lithiumophilic modification layer is a metal thin film material with high reactivity with lithium metal. Therefore, the presence of the lithiumophilic modification layer can improve the lithiumophilicity of the copper current collector, thereby enhancing the affinity between the lithium metal anode and the copper current collector, reducing the risk of battery short circuit during the assembly process. Compared with the original copper current collector or other methods for interfacial regulation between modified lithium metal and copper, the preparation method of the lithiumophilic modification layer used in this method is simple and easy to operate, which can effectively improve the safety performance and electrochemical performance of liquid and solid lithium metal batteries, and the preparation process is simple, the equipment cost is low, and it is suitable for large-scale surface treatment of copper current collectors.

[0031] (2) The lithiumophilic composite copper current collector obtained by the preparation method provided by the present invention can be used in traditional liquid and solid lithium metal batteries. Description of the Drawings

[0032] Figure 1 It is a schematic flow chart of a preparation method of a lithiumophilic composite copper current collector in an embodiment of the present application;

[0033] Figure 2 It is a lithium deposition curve graph of a lithium / copper half-cell assembled with a copper current collector treated in Example 1;

[0034] Figure 3 It is a lithium deposition curve graph of a lithium / copper half-cell assembled with a copper current collector treated in Comparative Example 1;

[0035] Figure 4 It is a lithium deposition curve graph of a lithium / copper half-cell assembled with a copper current collector treated in Comparative Example 2;

[0036] Figure 5 It is a lithium deposition curve graph of a lithium / copper half-cell assembled with a copper current collector treated in Example 9;

[0037] Figure 6 It is a lithium deposition curve graph of a lithium / copper half-cell assembled with a copper current collector treated in Comparative Example 3;

[0038] Figure 7 Lithium deposition curve of a lithium / copper half-cell assembled with a copper current collector not treated with Comparative Example 4. Detailed implementation manners

[0039] The following further describes in detail the implementation manners of the present disclosure in conjunction with the drawings and embodiments. The detailed descriptions and drawings of the following embodiments are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure, that is, the present disclosure is not limited to the described embodiments.

[0040] The "ranges" disclosed herein are defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The ranges defined in this way can include or exclude the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present disclosure, unless otherwise specified, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] In the present disclosure, if there is no special instruction, all the implementation manners and preferred implementation manners mentioned herein can be combined with each other to form a new technical solution.

[0042] In the present disclosure, if there is no special instruction, all the technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0043] In the present disclosure, unless otherwise specified, all steps mentioned herein can be carried out sequentially or randomly, but preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may also include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0044] An embodiment of the present application provides a method for preparing a lithiumophilic composite copper current collector. Please refer to Figure 1 as shown, the preparation method includes the following steps:

[0045] Step 1: Immerse the copper current collector in an acidic solution to remove the oxide film on the surface;

[0046] Step 2: Deposit a lithiumophilic modification layer on the surface of the copper current collector by physical deposition or electrochemical deposition to obtain a lithiumophilic composite copper current collector; wherein, the lithiumophilic modification layer is a metal thin film material with high reactivity with metallic lithium.

[0047] In the embodiment of the present application, the copper current collector is acid-treated to remove the oxide film on the surface, and then a lithiumophilic modification layer is deposited on the surface of the copper current collector by physical deposition or electrochemical deposition. The lithiumophilic modification layer is a metal thin film material with high reactivity with metallic lithium. Thus, the presence of the lithiumophilic modification layer can effectively improve the affinity of the copper current collector for the lithium metal negative electrode, and then can solve the problem of poor affinity caused by the electrochemical inertness of the traditional copper current collector and the lithium metal negative electrode, and can reduce the short-circuit problem caused by lithium stripping during the assembly process of the metal lithium battery pack. Moreover, the preparation method of the present application has a simple process and strong operability, and is suitable for large-scale surface treatment of copper current collectors.

[0048] In Step 1, the copper current collector is one of copper foil, copper foam, and porous copper; the acidic solution is one or more of dilute hydrochloric acid, dilute nitric acid, and dilute sulfuric acid.

[0049] In some embodiments, depositing a lithiumophilic modification layer on the surface of the copper current collector by physical deposition includes the following steps:

[0050] A lithiophilic metal is deposited on the surface of a copper current collector by physical deposition to deposit a lithiophilic modification layer on the surface of the copper current collector; wherein, the lithiophilic metal is one of tin, silver, zinc, and aluminum; the physical deposition method is one of magnetron sputtering, atomic layer deposition, and thermal evaporation, the deposition time of the physical deposition method is 1 - 60 min, and the deposition vacuum degree is 0.001 - 1 Pa.

[0051] In this embodiment, the lithiophilic metal is converted into a vapor state or an ionized state by physical deposition methods such as thermal evaporation, magnetron sputtering, or atomic layer deposition, and thus a thin film is condensed on the surface of the copper current collector. This thin film can effectively improve the affinity of the copper current collector for the lithium metal negative electrode and prevent the problem of lithium flaking during the assembly process.

[0052] In some other embodiments, a lithiophilic modification layer is deposited on the surface of the copper current collector by electrochemical deposition, including the following steps:

[0053] Provide a plating solution with a certain concentration, place the lithiophilic metal to be deposited on the anode side, and use the copper current collector as the substrate on the cathode side; on the surface of the copper current collector on the cathode side, electrochemically deposit a lithiophilic modification layer at a certain current density; wherein, the concentration of the plating solution is 0.1 - 1 M, the plating solution is one or several of magnesium sulfate, magnesium chloride, magnesium nitrate, zinc sulfate, zinc nitrate, zinc chloride, indium chloride, and tin chloride, and the current density is 0.1 - 10 mA / cm 2 , the plating time is 1 - 120 min, and the lithiophilic metal is one of magnesium, zinc, indium, and tin.

[0054] In this embodiment, by using an electrolytic cell containing a suitable plating solution, the copper current collector and the lithiophilic metal to be deposited are respectively placed on the anode and cathode of the electrolytic cell; a thin film of lithiophilic metal is deposited on the surface of the copper current collector on the cathode side at a certain current density. This thin film can effectively alleviate the problem of poor affinity between the copper current collector and the lithium metal negative electrode and reduce the short - circuit risk caused by lithium flaking during the assembly of metal lithium batteries.

[0055] The following describes the embodiments of depositing a lithiophilic modification layer by physical deposition.

[0056] Example 1

[0057] Immerse the copper foil current collector in dilute hydrochloric acid to remove the oxide film on the surface of the copper foil; deposit a tin target on the surface of the copper foil current collector by magnetron sputtering deposition, the deposition time is 10 min, and the vacuum degree of the deposition chamber is 0.05 Pa; bond the lithiated copper foil current collector with metallic lithium and heat it, the heating temperature is 220 °C, and the heating time is 30 min.

[0058] Example 2

[0059] Example 2 is different from Example 1 in that the copper current collector is porous copper.

[0060] Example 3

[0061] Example 3 is different from Example 1 in that the magnetron sputtering target used is a silver target.

[0062] Example 4

[0063] Example 4 is different from Example 1 in that the deposition time used is 15 min.

[0064] Example 5

[0065] Example 5 is different from Example 1 in that the vacuum degree of the deposition chamber used is 0.02 Pa.

[0066] Example 6

[0067] Example 6 is different from Example 1 in that the physical deposition method used is thermal evaporation.

[0068] Example 7

[0069] Example 7 is different from Example 1 in that the heating temperature for bonding the lithiumated copper foil to metallic lithium is 300 °C.

[0070] Example 8

[0071] Example 8 is different from Example 1 in that the heating time for bonding the lithiumated copper foil to metallic lithium is 15 min.

[0072] Comparative Example 1

[0073] Comparative Example 1 is different from Example 1 in that no lithiumophilic modification layer is deposited on the surface of the copper current collector of Comparative Example 1, and the copper foil current collector only subjected to pickling is directly assembled into a lithium / copper half-cell for electrochemical performance testing.

[0074] Comparative Example 2

[0075] Comparative Example 2 is different from Example 1 in that the magnetron sputtering target used in Comparative Example 2 is a nickel target.

[0076] The parameter differences between Examples 1-8 are shown in Table 1

[0077]

[0078] Test method

[0079] Step 1. Assembly of lithium / copper half-cell

[0080] The affinity between the copper current collector and metallic lithium can be verified by assembling lithium / copper half-cells and measuring the changing trends of lithium nucleation and deposition overpotentials. The copper current collector was processed according to each example and comparative example, with a diameter (φ) of 15 mm; a metallic lithium sheet was used as the counter electrode, with a diameter (φ) of 14 mm; an LB303-type electrolyte was added, and 2032-type button cells were assembled with a cell pressure of 70 kPa.

[0081] Step 2: Testing of lithium-copper half-cells

[0082] At room temperature (25 °C), after the cells were assembled, they were left standing for 60 min, and lithium was deposited at a current density of 0.5 mA / cm 2 for 2 h, and the capacity per unit area of deposition was 1 mAh / cm 2 .

[0083] The performance parameter results of each example and comparative example prepared by the above testing method are shown in Table 2.

[0084] Table 2. Comparison of performance parameters of Examples 1-8 and Comparative Examples 1 and 2 of the present invention

[0085] Example Thickness of lithiumophilic layer (nm) Lithium nucleation overpotential (mV) Lithium deposition overpotential (mV) Example 1 15 21.5 14.3 Example 2 8 8.9 7.7 Example 3 15 19.9 18.2 Example 4 15 25.6 23.7 Example 5 15 22.8 17.1 Example 6 10 18.6 11.7 Example 7 20 23.8 17.5 Example 8 10 22.0 17.8 Comparative Example 1 0 70.6 69.8 Comparative Example 2 15 63.9 93.2

[0086] As can be seen from the results presented in Table 1, the data of the lithiumophilic modification layer thickness, lithium nucleation overpotential, and lithium deposition overpotential of lithium / copper half-cells for Examples 1-8 and Comparative Examples 1 and 2 are shown in Table 2. Figure 2 The lithium deposition curve of the lithium / copper half-cell assembled with the copper current collector treated in Example 1 is shown. Its lithium nucleation overpotential and lithium deposition overpotential are 21.5 mV and 14.3 mV, respectively. In contrast, when not subjected to lithiumophilic modification, due to the lithium-phobic property of the copper foil, the polarization of the half-cell increases significantly. Figure 3 The polarization curve of the lithium / copper half-cell assembled with the copper current collector treated in Comparative Example 1 is shown. Its lithium nucleation overpotential and lithium deposition overpotential are 70.6 mV and 69.8 mV, respectively. Figure 4 The lithium deposition curve of the lithium / copper half-cell assembled with the copper current collector treated in Comparative Example 2 is shown. Although it was also surface-treated, since nickel metal and lithium metal cannot form an electrochemical alloy, the overpotential of the half-cell is also significantly higher than that of Example 1, and its lithium nucleation overpotential and lithium deposition overpotential are 63.9 mV and 93.2 mV, respectively.

[0087] Next, examples of depositing a lithiumophilic modification layer by electrochemical deposition are described.

[0088] Example 9

[0089] The copper foil current collector was immersed in dilute hydrochloric acid for acid treatment to remove the surface oxide film; a 0.1 M magnesium chloride electroplating solution was prepared, the metal magnesium to be deposited was placed on the anode side, and the copper foil was used as the substrate and placed on the cathode side; on the surface of the copper foil on the cathode side, magnesium was electrochemically deposited at a current density of 0.5 mA / cm 2 and the deposition time was 10 min to form a magnesium thin film.

[0090] Example 10

[0091] The difference from Example 9 was that the copper current collector was porous copper.

[0092] Example 11

[0093] The difference from Example 9 was that the copper current collector was copper foam.

[0094] Example 12

[0095] The difference from Example 9 was that the electroplating solution used was magnesium nitrate.

[0096] Example 13

[0097] The difference from Example 9 was that the electroplating solution used was zinc nitrate and the anode metal material was metal zinc.

[0098] Example 14

[0099] The difference from Example 9 was that the electroplating solution concentration was 0.5 M.

[0100] Example 15

[0101] The difference from Example 9 was that the electroplating current density was 0.6 mA / cm 2 .

[0102] Example 16

[0103] The difference from Example 9 was that the electroplating current density was 0.15 mA / cm 2 .

[0104] Example 17

[0105] The difference from Example 9 was that the electroplating time was 20 min.

[0106] Example 18

[0107] The difference from Example 9 was that the electroplating time was 5 min.

[0108] Comparative Example 3

[0109] Different from Example 9, a lithiumophilic modification layer is not deposited on the surface of the copper foil current collector in Comparative Example 3. The copper foil current collector only subjected to pickling is directly assembled into a lithium / copper half-cell for electrochemical performance testing.

[0110] Comparative Example 4

[0111] Different from Example 9, the electroplating solution used in Comparative Example 4 is ferric chloride, and the anode metal material is metallic iron.

[0112] The parameter differences between Examples 9-18 are shown in Table 3

[0113]

[0114]

[0115] Test method

[0116] Step 1. Assembly of lithium / copper half-cell

[0117] The affinity between the copper current collector and metallic lithium can be verified by assembling a lithium / copper half-cell combination group and measuring the change trend of lithium nucleation and deposition overpotential. The copper current collector is processed according to each example and comparative example, with φ being 15 mm; a metallic lithium sheet is used as the counter electrode, with φ being 14 mm; an LB303 type electrolyte is added, and a 2032 type button cell is assembled, and the battery pressure is 70 kPa.

[0118] Step 2. Testing of lithium-copper half-cell

[0119] At room temperature (25 °C), after the battery is assembled, it is left standing for 60 min, and lithium deposition is carried out at a current density of 0.3 mA / cm 2 The deposition time is 2 h, and the deposition capacity per unit area is 1 mAh / cm 2 .

[0120] The performance parameter results of each example and comparative example prepared by the above test method are shown in Table 4.

[0121] Table 4. Comparison of performance parameters of Examples 9-18, Comparative Example 3, and Comparative Example 4 of the present invention

[0122] Example Thickness of lithiumophilic layer (nm) Lithium nucleation overpotential (mV) Lithium deposition overpotential (mV) Example 9 50 20.5 15.1 Example 10 15 8.7 5.5 Example 11 15 9.0 5.3 Example 12 50 21.2 16.1 Example 13 45 23.1 13.2 Example 14 55 19.7 14.5 Example 15 100 18.9 16.0 Example 16 25 22.3 17.7 Example 17 100 18.9 15.2 Example 18 25 20.2 16.3 Comparative Example 3 0 63.2 102.9 Comparative Example 4 50 88.3 91.6

[0123] It can be seen from the results presented in Table 4 that the lithiumophilic modification layer thickness, lithium nucleation overpotential, and lithium deposition overpotential data of Examples 9-18 and Comparative Examples 3 and 4 are shown in Table 4. Figure 5The figure shows the lithium deposition curve of a lithium / copper half-cell assembled with a copper current collector treated in Example 9, and its lithium nucleation overpotential and lithium deposition overpotential are 20.5 mV and 15.1 mV respectively. In contrast, when not subjected to lithiophilic modification, due to the lithium-phobic property of the copper foil, the polarization of the half-cell increases significantly. Figure 6 The figure shows the polarization curve of a lithium / copper half-cell assembled with a copper current collector treated in Comparative Example 3, and its lithium nucleation overpotential and lithium deposition overpotential are 63.2 mV and 102.9 mV respectively. Figure 7 The figure shows the lithium deposition curve of a lithium / copper half-cell assembled with a copper current collector treated in Comparative Example 4. Although it has also been surface electroplated, since no electrochemical alloy can be formed between iron metal and lithium metal, the overpotential of the half-cell is also significantly higher than that of Example 1, and its lithium nucleation overpotential and lithium deposition overpotential are 88.3 mV and 91.6 mV respectively.

[0124] It can be understood that the present invention is described by means of some embodiments. Those skilled in the art know that, without departing from the spirit and scope of the present invention, various changes or equivalent substitutions can be made to these features and embodiments. Additionally, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present invention belong to the scope protected by the present invention.

Claims

1. A preparation method of a lithiumophilic composite copper current collector, characterized in that, The preparation method comprises the following steps:

1. Immerse the copper current collector in an acidic solution to remove the oxide film on the surface; 2. Deposit a lithiumophilic modification layer on the surface of the copper current collector by physical deposition or electrochemical deposition to obtain a lithiumophilic composite copper current collector; Among them, the lithiumophilic modification layer is a metal thin film material with high reactivity with metallic lithium.

2. The preparation method according to claim 1, characterized in that The step of depositing a lithiumophilic modification layer on the surface of the copper current collector by physical deposition includes the following steps: Deposit a lithiumophilic metal on the surface of the copper current collector by physical deposition to deposit a lithiumophilic modification layer on the surface of the copper current collector; among them, the lithiumophilic metal is one of tin, silver, zinc, and aluminum; the physical deposition method is one of magnetron sputtering, atomic layer deposition, and thermal evaporation.

3. The preparation method according to claim 2, characterized in that The deposition time of the physical deposition method is 1-60 min, and the deposition vacuum degree is 0.001-1 Pa.

4. The preparation method according to claim 1, characterized in that The step of depositing a lithiumophilic modification layer on the surface of the copper current collector by electrochemical deposition includes the following steps: Provide a plating solution with a certain concentration, place the lithiumophilic metal to be deposited on the anode side, and place the copper current collector as the substrate on the cathode side; Electrochemically deposit a lithiumophilic modification layer on the surface of the copper current collector on the cathode side at a certain current density.

5. The preparation method according to claim 4, characterized in that The concentration of the plating solution is 0.1-1 M; The current density is 0.1 - 10 mA / cm 2 , and the electroplating time is 1 - 120 min.

6. The preparation method according to claim 5, characterized in that The lithiumophilic metal is one of magnesium, zinc, indium, and tin; The plating solution is one or several of magnesium sulfate, magnesium chloride, magnesium nitrate, zinc sulfate, zinc nitrate, zinc chloride, indium chloride, and tin chloride.

7. The preparation method according to claim 1, characterized in that The copper current collector is one of copper foil, copper foam, and porous copper; And / or, the acidic solution is one or several of dilute hydrochloric acid, dilute nitric acid, and dilute sulfuric acid.

8. A negative electrode of a lithium metal battery, characterized in that, Bond the lithiumophilic composite copper current collector obtained by the preparation method according to any one of claims 1-7 with metallic lithium and heat it. After heat treatment for a certain time, a negative electrode of a lithium metal battery is obtained.

9. The negative electrode of a lithium metal battery according to claim 8, characterized in that The conditions of the heat treatment are: the heating temperature is 181-400 °C, and the heating time is 1-120 min.

10. A battery, comprising a positive electrode, a negative electrode and an electrolyte, characterized in that, The negative electrode is selected from the negative electrode of a lithium metal battery according to claim 8 or 9.

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