A modified negative electrode current collector and a preparation method and application thereof

Abstract

The application belongs to the technical field of battery materials, and particularly relates to a modified negative electrode current collector and a preparation method and application thereof. The negative electrode current collector comprises a Li2ZnCu3 alloy. After the Li2ZnCu3 alloy layer is used to modify the negative electrode current collector, the lithium affinity can be significantly improved, the nucleation barrier of lithium can be reduced, the Li2ZnCu3 alloy can be used as a uniform lithium nucleation site, the uniform deposition of lithium can be induced, the growth of dendrites can be inhibited, and the stability of a lithium / electrolyte interface and the cycle efficiency can be improved.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and specifically relates to a modified negative electrode current collector, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries are currently the most successful commercially available rechargeable batteries, widely used in emerging fields such as electric vehicles, aerospace, large-scale energy storage power stations, and mobile devices. However, the relatively low energy storage capacity of lithium-ion batteries limits their future application prospects. One major limiting factor is the low specific capacity of the graphite anode used in lithium-ion batteries, at only 372 mAh·g. -1 The search for a novel anode material to replace graphite has been put on the agenda. Lithium metal, compared to graphite anodes, has a specific capacity 10 times that of graphite (lithium metal specific capacity is 3860 mAh·g). -1 It possesses the lowest electrochemical reduction potential (-3.04 V vs. standard hydrogen electrode) and an extremely low mass density (0.534 g·cm³). -3 Theoretically, a battery using it as the negative electrode can easily achieve a yield higher than 400 Wh·kJ. -1 The energy density of lithium is sufficient to fully meet future needs. However, lithium resources on Earth are unevenly distributed and limited. Therefore, reducing dependence on lithium and developing new lithium metal-based batteries (including lithium metal batteries and negative electrode-free lithium metal batteries) that can operate stably in lithium-poor or lithium-free environments are key priorities for future energy storage.

[0003] Based on the above advantages, research on electrode materials for lithium metal batteries and anode-less lithium metal batteries has shown an increasing trend in recent years. However, the current collector electrodes developed for use in lithium metal batteries and anode-less lithium metal batteries still have many shortcomings, such as high production costs, complex processes, and stringent conditions. In addition, achieving uniform lithium deposition morphology is also quite difficult, limiting the long-cycle performance and safety of lithium metal-based batteries.

[0004] Therefore, finding a novel negative electrode current collector that can be rapidly and cost-effectively prepared and has the ability to achieve uniform lithium deposition, thereby improving battery cycle performance, has become an essential path to solving the problems of future commercial applications of lithium metal-based batteries. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0006] Therefore, the first objective of this invention is to provide a modified negative electrode current collector.

[0007] The second objective of this invention is to provide a method for preparing a modified negative electrode current collector.

[0008] A third objective of this invention is to propose an application of a modified negative electrode current collector.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A modified negative electrode current collector, comprising a Li2ZnCu3 alloy.

[0011] Preferably, the negative electrode current collector includes a metal foil and a Li2ZnCu3 alloy located on the surface of the metal foil.

[0012] Preferably, the metal sheet is copper foil.

[0013] Preferably, the thickness of the copper foil is 4.5-22 μm; more preferably, the thickness of the copper foil is 4.5-20 μm.

[0014] Preferably, the modified negative electrode current collector, from bottom to top, includes a copper foil layer and a Li2ZnCu3 alloy layer.

[0015] A method for preparing a modified negative electrode current collector includes the following steps:

[0016] (1) Mix Zn and Li under a protective atmosphere and heat to melt them to obtain a molten metal liquid;

[0017] (2) Heat the metal foil, then coat the surface of the metal foil with the molten metal liquid, keep it warm, and cool it to obtain the modified negative electrode current collector.

[0018] Preferably, in step (1), the protective atmosphere is a rare gas, such as argon.

[0019] Preferably, in step (1), the mass ratio of Zn to Li is 1:(1-25), more preferably 1:(1-20).

[0020] Preferably, in step (1), the Zn and Li are added in the form of Zn sheets and Li sheets.

[0021] Preferably, in step (1), the heating and melting temperature is 200-400℃.

[0022] Preferably, in step (1), after heating and melting, the molten metal liquid is stirred for 10-80 minutes, for example, by stirring with tweezers.

[0023] Preferably, in step (2), the metal foil is copper foil.

[0024] Preferably, in step (2), the heating temperature is 170-250℃, more preferably 180-220℃.

[0025] Preferably, in step (2), the heating time is 5-65 minutes, preferably 5-60 minutes.

[0026] Preferably, in step (2), the molten metal liquid is coated onto the surface of the metal foil using a stainless steel scraper.

[0027] Preferably, in step (2), the temperature of the heat preservation is 170-250℃ and the heat preservation time is 1-40 minutes; more preferably, the temperature of the heat preservation is 180-220℃ and the heat preservation time is 1-30 minutes.

[0028] Preferably, in step (2), after cooling, the metal foil is immersed in an ethanol solution, then washed with deionized water and dried to obtain the modified negative electrode current collector. Coating the molten metal liquid onto the surface of the metal foil and maintaining its temperature forms a Li2ZnCu3 alloy. Immersing the metal foil in the ethanol solution removes the mixed metal layer (a Li-Zn mixture) from the surface of the Li2ZnCu3 alloy.

[0029] Preferably, in step (2), the volume concentration of the ethanol solution is 75-99.5%, for example, 95%.

[0030] Preferably, in step (2), the soaking time is 10-70 minutes, preferably 10-60 minutes.

[0031] Preferably, in step (2), the drying is performed in an oven at 30-80°C for 5-60 minutes.

[0032] The above method was used to prepare a negative electrode current collector modified with Li2ZnCu3 alloy.

[0033] A metal-based battery comprising the above-modified negative electrode current collector.

[0034] Preferably, the metal-based battery includes any one of lithium, potassium, sodium, calcium, and magnesium metal-based batteries.

[0035] The application of the modified negative electrode current collector in battery fabrication.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] This invention provides a method for preparing a modified negative electrode current collector. The method first uses Li and Zn as raw materials to obtain a molten metal liquid (lithium-zinc liquid) through an alloying reaction at high temperature. The molten metal liquid is mainly composed of LiZn alloy and Li. Then, the molten metal liquid is transferred to a heated copper foil and uniformly covered on the surface of the copper foil with a stainless steel scraper. Under high temperature heating conditions, the LiZn alloy and Li will further undergo an alloying reaction with the copper foil substrate, namely Li + LiZn + 3Cu → Li2ZnCu3, forming a ternary Li2ZnCu3 alloy layer in situ on the surface of the copper foil. By reasonably controlling the mass ratio of Li and Zn, the heating temperature of the copper foil and the heating time, the thickness of the final Li2ZnCu3 alloy layer can be controlled to ensure the uniformity of the composition on the surface of the copper foil. Compared to a simple copper foil substrate, modification with a Li2ZnCu3 alloy layer significantly enhances lithiophilicity, reduces the lithium nucleation barrier, and provides uniform lithium nucleation sites, inducing uniform lithium deposition, suppressing dendrite growth, and improving the stability and cycle efficiency of the lithium / electrolyte interface. The mass of the copper foil modified with the Li2ZnCu3 alloy layer is only slightly increased compared to the unmodified copper foil, indicating that the modification has a minimal impact on the energy density of lithium metal batteries. This method is simple, inexpensive, and requires minimal equipment, making it suitable for large-scale production. Furthermore, the Li2ZnCu3 alloy-modified negative electrode current collector can also be applied to other metal battery systems, such as potassium, sodium, calcium, and magnesium-based batteries. Attached Figure Description

[0038] Figure 1 X-ray diffraction patterns of the negative electrode current collector modified with Li2ZnCu3 alloy and the unmodified copper foil current collector prepared in Example 1;

[0039] Figure 2 The scanning electron microscope, energy dispersive X-ray mapping, and energy dispersive X-ray mapping of the Li2ZnCu3 alloy-modified negative electrode current collector prepared in Example 1 are the scanning electron microscope, energy dispersive X-ray mapping of the high-angle annular dark field image under transmission electron microscope.

[0040] Figure 3 This is a scanning electron microscope image of the negative electrode current collector modified with Li2ZnCu3 alloy in Example 4 after electrodeposition in a Li2ZnCu3||Cu half cell;

[0041] Figure 4 The images show the coulombic efficiency diagrams of lithium plating / stripping for the Li2ZnCu3||Cu and Li||Cu half-cells in Example 5, as well as the voltage-time diagrams for the Li-Li2ZnCu3@Cu||Li-Li2ZnCu3@Cu and Li-Cu||Li-Cu symmetric cells. Detailed Implementation

[0042] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0043] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0044] Example 1: Preparation of Li2ZnCu3 alloy modified negative electrode current collector

[0045] A modified negative electrode current collector, from bottom to top, includes a copper foil layer and a Li2ZnCu3 alloy layer.

[0046] A method for preparing a modified negative electrode current collector includes the following steps:

[0047] In an argon-protected glove box, Zn and Li flakes were mixed together at a mass ratio of 1:2 and heated to 250°C. After the Zn and Li flakes melted, they were stirred with tweezers to ensure thorough mixing for 20 minutes, resulting in molten metal. The uniformly mixed molten metal was then transferred to a 10 μm thick copper foil and heated to 200°C for 40 minutes. The molten metal was then evenly spread over the copper foil surface using a stainless steel scraper, and the heat was maintained (i.e., kept warm) to promote the formation of Li₂Zn on the copper foil surface. The Cu3 alloy was generated by heating at 200℃ for 5 minutes. The copper foil was then removed and cooled to room temperature. The copper foil was then taken out of the glove box and immersed in an ethanol solution (99% concentration) to remove the solidified mixed metal layer (a Li-Zn mixture) on the surface. The immersion time was 15 minutes. Finally, the copper foil was thoroughly rinsed with deionized water and dried in an oven at 40℃ for 5 minutes to obtain the modified negative electrode current collector (i.e., the negative electrode current collector modified with Li2ZnCu3 alloy, denoted as Li2ZnCu3@Cu).

[0048] Example 2

[0049] The negative electrode current collector modified with Li2ZnCu3 alloy prepared in Example 1 was subjected to XRD test.

[0050] The Li2ZnCu3 alloy-modified negative electrode current collector and the unmodified copper foil current collector (i.e., pure metallic copper foil current collector) prepared in Example 1 were placed on a Bruker D8 Advance XRD diffractometer, with the test angle range set from 20 to 100 degrees. The test results are shown in [Figure 1]. Figure 1 .

[0051] Figure 1 X-ray diffraction patterns of the negative electrode current collector modified with Li2ZnCu3 alloy and the unmodified copper foil current collector prepared in Example 1.

[0052] Depend on Figure 1 ( Figure 1 As indicated by "Intensity" and "degree" in the text, the prepared Li2ZnCu3 alloy-modified negative electrode current collector exhibits distinct diffraction peaks in the range of 20 to 100 degrees, located at 21.8, 42.5, 43.3, 44.6, 50.5, 51.9, 57.1, 69.4, 74.1, 76.7, 80.8, 89.9, 93.1, and 95.1°. Among these, the diffraction peaks at 43.3, 50.5, 74.1, 89.9, and 95.1° belong to the diffraction peaks of the copper foil current collector substrate, which is consistent with the diffraction peak positions of the unmodified copper foil (i.e., Cu foil) current collector. XRD diffraction peaks of the pure phase of the Li2ZnCu3 alloy (i.e., "SimulatedLi2ZnCu3") simulated using Vesta software revealed that the remaining diffraction peaks at 21.8, 42.5, 44.6, 51.9, 57.1, 69.4, 76.7, 80.8, and 93.1° are characteristic peaks of the Li2ZnCu3 alloy, indicating successful modification of the copper foil current collector with the Li2ZnCu3 alloy. Furthermore, no impurity peaks were observed besides the Li2ZnCu3 alloy and the copper foil, demonstrating that the preparation method of Example 1 can successfully prepare a negative electrode current collector modified with pure Li2ZnCu3 alloy, ensuring the purity of the sample.

[0053] Example 3

[0054] The surface morphology and cross-sectional morphology of the Li2ZnCu3 alloy-modified negative electrode current collector prepared in Example 1 were measured by SEM (scanning electron microscopy) and TEM (transmission electron microscopy). The results are as follows: Figure 2 As shown.

[0055] Figure 2 The images show scanning electron microscopy, energy-dispersive X-ray mapping, and energy-dispersive X-ray mapping of the high-angle annular dark-field image of the negative electrode current collector modified with Li2ZnCu3 alloy prepared in Example 1.

[0056] (1) The surface morphology of the negative electrode current collector modified with Li2ZnCu3 alloy prepared in Example 1 was tested by SEM.

[0057] The Li2ZnCu3 alloy-modified negative electrode current collector prepared in Example 1 was prepared on a surface morphology stage of an SEM, transferred to the chamber of a scanning electron microscope, and then subjected to surface morphology characterization after vacuuming. Figure 2 As shown in (a) and (b), compared to the smooth surface of the original copper foil current collector, the surface of the copper foil current collector after modification with Li2ZnCu3 alloy exhibits numerous uniformly distributed nanoparticles. These nanoparticles are composed of Li2ZnCu3 alloy. Benefiting from the high lithium affinity and uniform distribution of Li2ZnCu3 alloy, these Li2ZnCu3 alloy nanoparticles can effectively induce uniform lithium deposition on its surface and inhibit the growth of lithium dendrites.

[0058] (2) The cross-sectional morphology of the negative electrode current collector modified with Li2ZnCu3 alloy prepared in Example 1 was tested by SEM.

[0059] The Li2ZnCu3 alloy-modified negative electrode current collector prepared in Example 1 was prepared on a cross-sectional sample stage of an SEM, transferred to the chamber of a scanning electron microscope, and then subjected to vacuum for cross-sectional morphology characterization. Figure 2 As shown in (c), after modification with the Li2ZnCu3 alloy layer, a new structure clearly appeared on the copper foil and was tightly bonded to the copper foil substrate. According to... Figure 2 The energy-dispersive X-ray mapping results in (d) and (e) show a significant accumulation of Zn in the new structural layer, indicating that the layer is a Li₂ZnCu₃ alloy. Furthermore, compared to the original copper foil current collector thickness (10 μm), the thickness after Li₂ZnCu₃ alloy modification did not change significantly, indicating that the Li₂ZnCu₃ alloy modification does not substantially affect the volumetric energy density of the battery.

[0060] (3) TEM tests were performed on the negative electrode current collector modified with Li2ZnCu3 alloy prepared in Example 1.

[0061] The negative electrode current collector modified with Li2ZnCu3 alloy prepared in Example 1 was thinned by ion reduction, removing the bottom copper foil layer and reducing the thickness of the Li2ZnCu3 alloy layer to about 100 nm to facilitate TEM observation. Figure 2 As shown in (f), the Li2ZnCu3 alloy exhibits a nanoparticle structure under high-angle annular dark-field imaging, which is consistent with SEM observations. Furthermore, as... Figure 2 The mapping results of energy-dispersive X-rays in (g) and (h) show that copper and zinc elements are significantly enriched on these nanoparticles, further proving the successful preparation of Li2ZnCu3 alloy.

[0062] Example 4

[0063] Application of Li2ZnCu3 alloy-modified negative electrode current collector in lithium metal-based batteries.

[0064] The negative electrode current collector modified with the Li2ZnCu3 alloy prepared in Example 1 was matched with a lithium metal sheet to assemble a Li2ZnCu3@Cu||Li half-cell. The electrolyte consisted of 1 mol LiTFSI (lithium bis(trifluoromethanesulfonate)imide) dissolved in 1 L of DOL / DME (1,3-dioxolane / ethylene glycol dimethyl ether, volume ratio 1:1) solvent, with 2% LiNO3 added as an additive. The assembled Li2ZnCu3@Cu||Li half-cell was subjected to lithium electrodeposition tests using a blue electrode in a constant temperature oven at a current density of 1 mA·cm⁻¹. -2 Discharge was performed, and the capacity of the deposited lithium was 6 mAh·cm³. -2 Before lithium electrodeposition testing, the half-cell was left to stand for 6 hours to ensure complete wetting of the electrolyte inside the cell. Then, it was continuously charged and discharged 5 times at a current of 0.05 mA, with a voltage range of 0-1 V, to promote the formation of a solid electrolyte layer on the electrode surface. When the capacity of the deposited lithium reached 6 mAh·cm³, the electrode was successfully deposited. -2 Next, the battery was removed and disassembled in an argon-protected glove box. The electrodeposited Li2ZnCu3 alloy-modified negative electrode current collector was taken out, rinsed with DOL solvent using tweezers to remove residual electrolyte, then dried, and prepared onto a planar sample stage for SEM observation. The results are as follows: Figure 3 As shown.

[0065] Figure 3 This is a scanning electron microscope image of the negative electrode current collector modified with Li2ZnCu3 alloy in Example 4 after electrodeposition in a Li2ZnCu3||Cu half-cell.

[0066] like Figure 3 As shown in (a) and (b), the Li2ZnCu3 alloy-modified negative electrode current collector exhibits a uniform lithium deposition morphology without dendrite formation. This indicates that the Li2ZnCu3 alloy modification helps suppress dendrite growth on the current collector surface, promotes uniform lithium deposition, and improves the stability of the electrode / electrolyte interface. Furthermore, the Li2ZnCu3 alloy-modified negative electrode current collector has a high lithium loading capacity, perfectly matching existing positive electrodes (typically with capacities of 3-4 mAh·cm³). -2 This demonstrates its excellent cathode compatibility, which is conducive to the realization of high-energy-density lithium metal-based batteries.

[0067] Example 5

[0068] Application of Li2ZnCu3 alloy-modified negative electrode current collector in lithium metal-based batteries.

[0069] (1) The negative electrode current collector modified with Li2ZnCu3 alloy prepared in Example 1 and the copper foil current collector were matched with lithium metal sheets to assemble Li2ZnCu3@Cu||Li and Cu||Li half-cells, respectively. The electrolyte was 1 mol LiTFSI (lithium bis(trifluoromethanesulfonate)imide) dissolved in 1 L of DOL / DME (1,3-dioxolane / ethylene glycol dimethyl ether, volume ratio 1:1) solvent, with 2% LiNO3 additive added. The assembled Li2ZnCu3@Cu||Li and Cu||Li half-cells were tested for coulombic efficiency by lithium plating / stripping in a constant temperature oven using a blue electrode to test the promoting effect of the Li2ZnCu3 alloy modified negative electrode current collector on the reversible cycling of lithium. Before lithium electrodeposition testing, the half-cell was allowed to stand for 6 hours to ensure complete wetting of the electrolyte inside the cell. Then, it was continuously charged and discharged 5 times at a current of 0.05 mA, with a voltage range of 0-1 V, to promote the formation of a solid electrolyte layer on the electrode surface. The current density was 1 mA·cm⁻¹. -2 Discharge was performed, and the capacity of the deposited lithium was 1 mAh·cm³. -2 Lithium is electroplated onto the electrode surface, and then charged at the same current density until the battery voltage reaches 1V, indicating that the lithium plating on the electrode surface has been completely stripped off. This process is repeated, and the coulombic efficiency of the half-cell lithium plating / stripping is obtained by dividing the charging capacity by the discharging capacity. The results are as follows: Figure 4 As shown in (a).

[0070] Figure 4 The diagrams show the coulombic efficiency of the Li2ZnCu3||Cu and Li||Cu half-cells in Example 5, based on lithium plating / stripping, and the voltage-time diagrams of the Li-Li2ZnCu3@Cu||Li-Li2ZnCu3@Cu and Li-Cu||Li-Cu symmetrical cells. Figure 4 In this context, "coulombic efficiency" refers to the coulombic efficiency, "Cycle number" refers to the number of cycles, "Average CE" refers to the average coulombic efficiency, "Voltage" refers to the voltage, and "Time" refers to the time.

[0071] like Figure 4As shown in Figure (a), the Li₂ZnCu₃@Cu||Li half-cell exhibits a higher initial coulombic efficiency compared to the Cu||Li half-cell, and can maintain a stable average coulombic efficiency of 97.9% for 200 cycles. In contrast, the Cu||Li half-cell can only maintain a high coulombic efficiency for 100 cycles before experiencing a rapid decline in coulombic efficiency, leading to battery failure. This is mainly due to the improved lithium deposition morphology on the surface of the negative electrode current collector and the stabilization of the electrode / electrolyte interface resulting from Li₂ZnCu₃ modification. Therefore, the Li₂ZnCu₃@Cu||Li half-cell reduces the occurrence of side reactions during cycling and improves the reversibility of lithium plating / stripping, further demonstrating the application potential and commercial prospects of Li₂ZnCu₃ alloy-modified negative electrode current collectors in lithium metal-based batteries.

[0072] (2) The negative electrode current collector and copper foil current collector modified with the Li2ZnCu3 alloy prepared in Example 1 were matched with lithium metal sheets to assemble Li2ZnCu3@Cu||Li and Cu||Li half-cells, respectively. The electrolyte consisted of 1 mol LiTFSI (lithium bis(trifluoromethanesulfonate)) dissolved in 1 L of DOL / DME (1,3-dioxolane / ethylene glycol dimethyl ether, volume ratio 1:1) solvent, with 2% LiNO3 additive added. The assembled Li2ZnCu3@Cu||Li and Cu||Li half-cells were subjected to lithium electrodeposition using a blue electrode in a constant temperature oven at a current density of 1 mA·cm⁻¹. -2 Discharge was performed, and the capacity of the deposited lithium was 1 mAh·cm³. -2 When the capacity of the deposited lithium reaches 6 mAh·cm³ -2 Next, the battery was removed and disassembled in an argon-protected glove box. The electrodeposited Li2ZnCu3 alloy-modified negative electrode current collector and copper foil current collector were taken out and rinsed with DOL solvent using tweezers to remove residual electrolyte. They were then air-dried to obtain Li-Li2ZnCu3@Cu and Li-Cu electrodes with lithium metal deposition on their surfaces. Two identical Li-Li2ZnCu3@Cu and Li-Cu electrodes were used to assemble symmetrical cells, using the same electrolyte as the half-cell. These were assembled into Li-Li2ZnCu3@Cu||Li-Li2ZnCu3@Cu and Li-Cu||Li-Cu symmetrical cells, and lithium symmetrical cell tests were performed to investigate their voltage stability under repeated lithium plating / stripping. The current density used was 1 mA·cm⁻¹. -2 The capacity of lithium obtained through repeated electroplating / stripping is 1 mAh·cm³. -2 The result is as follows Figure 4 As shown in (b).

[0073] like Figure 4As shown in (b), the Li-Li2ZnCu3@Cu||Li-Li2ZnCu3@Cu symmetric cell exhibits a stable plating / stripping voltage plateau and can operate smoothly for 500 hours, while the Li-Cu||Li-Cu symmetric cell only operates normally for 320 hours before failing due to a sharp increase in voltage. This further demonstrates that the presence of the Li2ZnCu3 modification layer helps achieve uniform lithium deposition and improves the lithium plating / stripping behavior. Furthermore, this performance is also superior to the symmetric cell performance in CN115763699 A.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A negative electrode current collector, characterized in that, The negative electrode current collector includes a metal foil and a Li2ZnCu3 alloy located on the surface of the metal foil; the metal foil is a copper foil. The negative electrode current collector is prepared by a method comprising the following steps: (1) Mix Zn and Li under a protective atmosphere and heat to melt them to obtain a molten metal liquid; (2) Heat the metal foil, then coat the molten metal liquid onto the surface of the metal foil, keep it warm, cool it, and after cooling, immerse the metal foil in an ethanol solution to remove the solidified mixed metal layer on the surface. The mixed metal layer is a Li-Zn mixture. Then wash it with deionized water and dry it to obtain the negative electrode current collector.

2. The negative electrode current collector according to claim 1, characterized in that, The thickness of the copper foil is 4.5-22 μm.

3. The method for preparing the negative electrode current collector according to any one of claims 1-2, characterized in that, Includes the following steps: (1) Mix Zn and Li under a protective atmosphere and heat to melt them to obtain a molten metal liquid; (2) Heat the metal foil, then coat the molten metal liquid onto the surface of the metal foil, keep it warm, cool it, and after cooling, immerse the metal foil in an ethanol solution to remove the solidified mixed metal layer on the surface. The mixed metal layer is a Li-Zn mixture. Then wash it with deionized water and dry it to obtain the negative electrode current collector.

4. The preparation method according to claim 3, characterized in that, In step (1), the mass ratio of Zn to Li is 1:(1-25).

5. The preparation method according to claim 3, characterized in that, In step (2), the metal foil is copper foil; in step (2), the heating temperature is 170-250℃; in step (2), the heat preservation temperature is 170-250℃, and the heat preservation time is 1-40 minutes.

6. A lithium metal battery, characterized in that, Includes the negative electrode current collector as described in any one of claims 1-2.

7. The application of the negative electrode current collector according to any one of claims 1-2 in the preparation of a battery.

Images