Zinc oxide nanosheet modified copper-based current collector and preparation method and application thereof

Abstract

The invention provides a zinc oxide nanosheet modified copper-based current collector as well as a preparation method and application thereof, and relates to the technical field of lithium batteries. According to the zinc oxide nanosheet modified copper-based current collector, uniform deposition of lithium is effectively induced in the circulation process, dendritic crystal growth is inhibited, volume expansion is relieved, and the zinc oxide nanosheet modified copper-based current collector structurally comprises a copper foil substrate and a zinc oxide nanosheet modified layer which is of a three-dimensional porous structure and covers the surface of the copper foil substrate; the thickness of the matrix is 6-500 [mu] m, the thickness of the zinc oxide nanosheet modification layer is 1-1.5 [mu] m, and the pore size of the porous structure is 210-250 nm; the zinc oxide crystal phase is of a hexagonal wurtzite structure. The preparation method disclosed by the invention is obviously superior to the existing high-temperature heat treatment oxidation technology in the aspects of reaction conditions, morphology regulation and control, lithium affinity, process cost, environmental friendliness and the like, provides a simple, convenient, efficient and green new way for preparing the high-performance lithium metal battery negative electrode current collector, and has important technical progress significance and wide application prospects.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a zinc oxide nanosheet modified copper-based current collector, its preparation method, and its application. Background Technology

[0002] With the rapid development of the new energy market, the demand for high-energy-density rechargeable batteries is increasing. Lithium metal is favored due to its high theoretical capacity (3860 mAh / g) and low density (0.534 g / cm³). 3 With its excellent properties such as extremely low electrochemical potential (-3.04 V vs. standard hydrogen electrode), lithium metal anodes are considered ideal materials for next-generation high-energy-density battery anodes. However, lithium metal anodes face many challenges in practical applications, which severely restricts their commercialization process.

[0003] First, due to the high chemical reactivity of lithium, repeated lithium deposition / dissolution cycles easily lead to side reactions between the electrolyte and lithium, forming a mechanically poor and unstable solid electrolyte interface (SEI). Second, lithium metal lacks a stable host structure, and its volume undergoes drastic changes during charge and discharge, causing repeated SEI breakage and reformation, accelerating the loss of active lithium and reducing coulombic efficiency. Furthermore, traditional copper foil current collectors have high surface roughness and exhibit a significant tip effect, causing lithium ions to preferentially deposit at surface protrusions at low potentials, forming localized hot spots and promoting uncontrolled lithium dendrite growth. Lithium dendrites not only puncture the separator, causing battery short circuits and posing serious safety hazards, but also lead to rapid battery capacity decay and a significantly shortened cycle life.

[0004] To address these issues, researchers have conducted extensive work, among which surface modification of the negative electrode current collector has proven to be an effective strategy. By constructing a lithiophilic functional layer on the current collector surface, the lithium nucleation overpotential can be reduced, guiding uniform lithium deposition and thus suppressing dendrite growth. Zinc oxide (ZnO), as an important semiconductor material, possesses unique physicochemical properties: its nanosheet structure has an average size of approximately 50 nm, providing a high specific surface area and offering more reactive sites; simultaneously, ZnO exhibits excellent chemical stability, maintaining structural and performance stability under various environments, enabling it to retain functionality during long-term charge-discharge cycles. Furthermore, ZnO has a good affinity for lithium, effectively reducing the lithium nucleation barrier.

[0005] However, the preparation of ZnO modified layers in the prior art usually adopts a high-temperature thermal oxidation process. For example, relevant literature reports the use of chemical bath deposition combined with high-temperature thermal treatment above 800℃ to grow porous ZnO nanosheets on copper substrates. This high-temperature oxidation process has obvious shortcomings: (1) High temperature (≥800℃) can easily cause thermal stress, lattice distortion or even phase transformation in the substrate, which can damage the mechanical properties and service life of the material; (2) The oxidation rate is strongly affected by factors such as temperature, atmosphere and time, which can easily form an oxide layer with uneven thickness, porous or brittle, affecting the reliability and consistency of the product; (3) The high-temperature process relies on large heating equipment, which has high energy consumption, high maintenance costs and long production cycle; (4) It may release harmful gases such as nitrogen oxides and volatile organic compounds, which require an additional exhaust gas treatment system, increasing production costs and environmental burden; (5) It is difficult to accurately control the microstructure of the oxide layer.

[0006] Therefore, there is an urgent need to develop a mild, efficient, environmentally friendly preparation method that can precisely control the oxide layer structure to meet the preparation requirements of high-performance lithium metal battery anode current collectors. Summary of the Invention

[0007] In view of this, the present invention provides a zinc oxide nanosheet-modified copper-based current collector, its preparation method, and its application. The present invention significantly outperforms existing high-temperature thermal oxidation techniques in terms of reaction conditions, morphology control, lithiophilic properties, process cost, and environmental friendliness. It provides a simple, efficient, and green new approach for the preparation of high-performance lithium metal battery anode current collectors, possessing significant technological advancement and broad application prospects.

[0008] The first aspect of the present invention is to provide a copper-based current collector modified with zinc oxide nanosheets, comprising a copper foil substrate and a three-dimensional porous zinc oxide nanosheet modification layer covering its surface; The zinc oxide nanosheet-modified copper-based current collector is obtained by using copper foil as raw material, which is zinc-plated and then oxidized on the surface with ammonia. The thickness of the substrate is 6-500 μm, the thickness of the zinc oxide nanosheet modification layer is 1-1.5 μm, and the pore size of the porous structure is 210-250 nm; the zinc oxide crystal phase is hexagonal wurtzite structure.

[0009] A second aspect of this invention provides a method for preparing a copper-based current collector modified with zinc oxide nanosheets, specifically comprising the following steps: S1. Surface pretreatment: Remove impurities and stains from the copper foil surface; S2, zinc-plated copper foil: zinc is electroplated onto the surface of the copper foil pretreated by S1 to deposit zinc on the copper foil surface. After washing and drying, zinc-modified copper foil is obtained. S3, Ammonia Oxidation: The zinc-modified copper foil from step S2 is placed in an ammonia solution for oxidation, generating zinc oxide nanosheets on the zinc layer surface, resulting in a copper-based current collector modified with zinc oxide nanosheets.

[0010] Preferably, in step S1, the thickness of the copper foil is 6-500 μm; the surface pretreatment method is as follows: the copper foil is first immersed in 0.1 mol L... -1 Sonicate in dilute hydrochloric acid for 5 minutes, then immerse in acetone and sonicate for 5 minutes, then blow dry.

[0011] Preferably, in step S2, the electroplating method is as follows: the copper foil pretreated in S1 is placed in a zinc sulfate electrolyte, and electroplating is performed using a platinum sheet as the counter electrode, the copper foil sample as the working electrode, and a saturated calomel electrode as the reference electrode; the concentration of the zinc sulfate solution is 0.01%. -1 M, more preferably 0.5 M; the electroplating current is -0.2 A, and the electroplating time is 100 minutes. - 1 000 s, more preferably 300 s; the washing method is as follows: the surface of the copper foil after zinc deposition is rinsed sequentially with deionized water and anhydrous ethanol; the drying is vacuum drying, the drying temperature is 60℃, and the drying time is 12 h.

[0012] Preferably, in step S3, the ammonia concentration is 10-30 mM, the oxidation temperature is room temperature, and the oxidation time is 2-12 h. More preferably, the ammonia concentration is 10 mM, and the oxidation time is 4 h.

[0013] A third aspect of the present invention is to provide an application of a zinc oxide nanosheet-modified copper-based current collector as a lithium battery electrode material, wherein the zinc oxide nanosheet-modified copper-based current collector is the zinc oxide nanosheet-modified copper-based current collector described above.

[0014] Preferably, the diameter of the electrode is 12-16 mm.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention employs an ammonia-based wet chemical oxidation process, enabling the preparation of zinc oxide nanosheets at room temperature. This completely avoids the structural damage to the copper foil substrate caused by traditional high-temperature heat treatment oxidation, such as thermal stress, lattice distortion, and phase transformation. It maximizes the preservation of the original properties and mechanical strength of the substrate, extending the service life of the material.

[0016] The ammonia solution used in this invention, as a weakly alkaline solution, can gently etch the zinc layer surface and synergistically induce an oxidation reaction, generating a uniform and dense three-dimensional porous zinc oxide nanosheet structure in situ on the zinc layer surface. This unique porous structure significantly increases the specific surface area, provides more active sites for lithium ion deposition, effectively reduces local current density, and guides uniform lithium deposition. In contrast, high-temperature thermal oxidation can only achieve the chemical transformation of surface materials, making it difficult to precisely control the microstructure and easily forming an oxide layer of uneven thickness.

[0017] The zinc oxide nanosheet-modified current collector of this invention exhibits excellent lithium affinity. Zinc oxide can reduce the nucleation overpotential of lithium, promoting uniform lithium nucleation and deposition. Compared with pure copper foil, the lithium deposition thickness on the zinc oxide-modified current collector is thinner and more uniform, significantly improving battery cycle performance, reducing voltage polarization, extending cycle life, effectively suppressing lithium dendrite growth, and enhancing battery safety and cycle stability.

[0018] The preparation process of this invention includes three main steps: surface pretreatment, electroplating a zinc layer, and ammonia oxidation. It is simple to operate, requires no complex high-temperature equipment, and the entire preparation process is fast and efficient. Ammonia, as a common chemical, is inexpensive and recyclable, requiring minimal equipment investment and low energy consumption, making it suitable for large-scale industrial production. The production cost is far lower than that of high-temperature heat treatment processes.

[0019] The ammonia oxidation process is carried out at room temperature to medium temperature, with extremely low energy consumption. The ammonia can be recycled and reused, reducing chemical consumption. The entire process is green and environmentally friendly, in line with the concepts of green chemistry and sustainable development, and has good environmental and social benefits.

[0020] When the zinc oxide nanosheets prepared in this invention are used to modify copper-based current collectors as anodes in lithium metal batteries, they exhibit excellent electrochemical performance, uniform lithium deposition behavior, high utilization rate, and significantly improved battery capacity retention and cycle stability.

[0021] This invention can precisely control the zinc layer thickness and the morphology of zinc oxide nanosheets by adjusting process parameters such as electroplating time, zinc sulfate concentration, ammonia concentration, and immersion time. The process has good reproducibility, stable product quality, and is easy to standardize. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 This is a process flow diagram of the method for preparing zinc oxide nanosheet-modified copper-based current collectors according to the present invention; Figure 2 This is a macroscopic photograph of the original commercial copper foil after pretreatment in Example 1 of the present invention, showing that the copper foil surface is smooth and reddish-copper in color; Figure 3 This is a macroscopic photograph of the zinc-modified copper foil in Embodiment 3 of the present invention, showing that the copper foil surface is covered with a silver-gray zinc layer after electroplating. Figure 4 This is a macroscopic photograph of the zinc oxide nanosheet-modified copper foil in Example 3 of the present invention, showing that the copper foil surface has a grayish-white zinc oxide layer after oxidation with ammonia. Figure 5 The image shows a scanning electron microscope (SEM) image of the original copper foil surface, with a magnification scale bar of 2 μm, revealing a relatively flat morphological feature on the copper foil surface. Figure 6 The image is a scanning electron microscope (SEM) image of the zinc oxide nanosheets modified copper foil surface prepared in Example 3 of this invention, with a magnification scale bar of 500 nm. Figure 7 The X-ray diffraction (XRD) pattern of the zinc oxide nanosheet-modified copper foil prepared in Example 3 of this invention is shown. The red curve is the diffraction pattern of the ZnO@Cu sample, and the black curve is the diffraction pattern of the pure copper foil. Standard card number: ZnO corresponds to JCPDS card 36-1451, and Cu corresponds to JCPDS card 04-0836. Figure 8 Cross-sectional SEM images comparing the lithium deposition behavior on two current collectors (pure copper foil and zinc oxide nanosheet-modified copper foil in Example 3), where: (a) is the cross-sectional morphology of the lithium deposition layer when pure copper foil is used as the current collector, with a lithium deposition layer thickness of approximately 17.14 μm and exhibiting a loose and porous structure; (b) is the cross-sectional morphology of the lithium deposition layer when zinc oxide nanosheet-modified copper foil is used as the current collector, with a lithium deposition layer thickness of approximately 9.14 μm and exhibiting a more dense and uniform structure; Figure 9 For 0.5 mA cm -2 The comparison graph shows the cycling performance of a symmetrical battery assembled with pure copper foil (black curve) and zinc oxide nanosheet modified copper foil (red curve) in Example 3 as current collectors at current density. The main graph is the voltage change curve over time during cycling; the sub-graph (b) is a magnified curve in the 500-600 hour range. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] The copper foil used in the embodiments and comparative examples of this invention is a commercially available planar copper foil with a size of 4 cm × 4 cm and a thickness of 11 μm.

[0026] Unless otherwise specified, all experiments were repeated three times. Results are expressed as mean ± standard deviation, and P < 0.05 indicates a significant difference.

[0027] Example 1: A method for preparing a copper-based current collector modified with zinc oxide nanosheets, comprising the following steps: S1. Surface pretreatment: Commercially available planar copper foil with a thickness of 11 μm was cut into 4 cm × 4 cm pieces and immersed in 0.1 mol L⁻¹ solution. -1 The copper foil was ultrasonically cleaned in dilute hydrochloric acid and acetone for 5 minutes, then air-dried to remove impurities, oil stains, and oxide layers from its surface. The surface morphology of the pretreated copper foil is as follows: Figure 2 As shown; S2, Copper foil with electroplated zinc layer: The copper foil pretreated in step S1 was placed in a 0.5 M zinc sulfate electrolyte. A three-electrode system was used for electrochemical deposition, with a platinum sheet as the counter electrode, the copper foil sample as the working electrode, and a saturated calomel electrode as the reference electrode. The electroplating current was set to -0.2 A, and the electroplating time was 100 s, under which zinc was uniformly deposited on the copper foil surface. After electroplating, the sample was rinsed sequentially with deionized water and anhydrous ethanol, and then air-dried to obtain zinc-modified copper foil. The macroscopic morphology of the zinc-modified copper foil is shown below. Figure 3 As shown; S3, ammonia oxidation: The zinc-modified copper foil obtained in step S2 was placed in a 10 mM ammonia solution and soaked at room temperature for 2 h. Zinc oxide nanosheets were generated in situ on the zinc layer surface through a wet chemical oxidation reaction. After soaking, the sample was washed with deionized water and anhydrous ethanol and dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based current collector modified with zinc oxide nanosheets.

[0028] Example 2: A method for preparing a copper-based current collector modified with zinc oxide nanosheets, comprising the following steps: S1. Surface pretreatment: Commercially available planar copper foil with a thickness of 11 μm was cut into 4 cm × 4 cm pieces and immersed in 0.1 mol L⁻¹ solution. -1 Ultrasonic cleaning in dilute hydrochloric acid and acetone for 5 minutes, followed by drying to remove impurities, oil stains and oxide layer from the copper foil surface; S2, Copper foil with electroplated zinc layer: The copper foil pretreated in step S1 was placed in a 0.5 M zinc sulfate electrolyte. A three-electrode system was used for electrochemical deposition, with a platinum sheet as the counter electrode, the copper foil sample as the working electrode, and a saturated calomel electrode as the reference electrode. The electroplating current was set to -0.2 A and the electroplating time was 300 s. Under these conditions, zinc was uniformly deposited on the surface of the copper foil. After electroplating, the sample was rinsed with deionized water and anhydrous ethanol in sequence and then dried to obtain zinc-modified copper foil. S3, ammonia oxidation: The zinc-modified copper foil obtained in step S2 was placed in a 10 mM ammonia solution and soaked at room temperature for 2 h. Zinc oxide nanosheets were generated in situ on the zinc layer surface through a wet chemical oxidation reaction. After soaking, the sample was washed with deionized water and anhydrous ethanol and dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based current collector modified with zinc oxide nanosheets.

[0029] Example 3: A method for preparing a copper-based current collector modified with zinc oxide nanosheets, comprising the following steps: S1. Surface pretreatment: Commercially available planar copper foil with a thickness of 11 μm was cut into 4 cm × 4 cm pieces and immersed in 0.1 mol L⁻¹ solution. -1 The copper foil was ultrasonically cleaned in dilute hydrochloric acid and acetone for 5 minutes, then dried to remove impurities, oil stains, and oxide layers from its surface. The SEM morphology of the original copper foil is shown below. Figure 5 As shown.

[0030] S2, Copper foil with electroplated zinc layer: The copper foil pretreated in step S1 was placed in a 0.5 M zinc sulfate electrolyte. A three-electrode system was used for electrochemical deposition, with a platinum sheet as the counter electrode, the copper foil sample as the working electrode, and a saturated calomel electrode as the reference electrode. The electroplating current was set to -0.2 A and the electroplating time was 300 s. Under these conditions, zinc was uniformly deposited on the surface of the copper foil. After electroplating, the sample was rinsed with deionized water and anhydrous ethanol in sequence and then dried to obtain zinc-modified copper foil. S3, ammonia oxidation: The zinc-modified copper foil obtained in step S2 was placed in a 10 mM ammonia solution and soaked at room temperature for 4 h. Zinc oxide nanosheets were generated in situ on the zinc layer surface through a wet chemical oxidation reaction. After soaking, the sample was washed with deionized water and anhydrous ethanol and dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based current collector modified with zinc oxide nanosheets.

[0031] Example 4: A method for preparing a copper-based current collector modified with zinc oxide nanosheets, comprising the following steps: S1. Surface pretreatment: Commercially available planar copper foil with a thickness of 11 μm was cut into 4 cm × 4 cm pieces and immersed in 0.1 mol L⁻¹ solution. -1 Ultrasonic cleaning in dilute hydrochloric acid and acetone for 5 minutes, followed by drying to remove impurities, oil stains and oxide layer from the copper foil surface; S2, Copper foil with electroplated zinc layer: The copper foil pretreated in step S1 was placed in a 0.5 M zinc sulfate electrolyte. A three-electrode system was used for electrochemical deposition, with a platinum sheet as the counter electrode, the copper foil sample as the working electrode, and a saturated calomel electrode as the reference electrode. The electroplating current was set to -0.2 A and the electroplating time was 300 s. Under these conditions, zinc was uniformly deposited on the surface of the copper foil. After electroplating, the sample was rinsed with deionized water and anhydrous ethanol in sequence and then dried to obtain zinc-modified copper foil. S3, ammonia oxidation: The zinc-modified copper foil obtained in step S2 was placed in a 20 mM ammonia solution and soaked at room temperature for 4 h. Zinc oxide nanosheets were generated in situ on the zinc layer surface through a wet chemical oxidation reaction. After soaking, the sample was washed with deionized water and anhydrous ethanol and dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based current collector modified with zinc oxide nanosheets.

[0032] Example 5: Application of a zinc oxide nanosheet-modified copper-based current collector in lithium metal batteries, the steps are as follows: S1. Surface pretreatment: Commercially available planar copper foil with a thickness of 11 μm was cut into 4 cm × 4 cm pieces and immersed in 0.1 mol L⁻¹ solution. -1 Ultrasonic cleaning in dilute hydrochloric acid and acetone for 5 minutes, followed by drying to remove impurities, oil stains and oxide layer from the copper foil surface; S2, Copper foil with electroplated zinc layer: The copper foil pretreated in step S1 was placed in a 0.5 M zinc sulfate electrolyte. A platinum sheet was used as the counter electrode, the copper foil sample as the working electrode, and a saturated calomel electrode as the reference electrode. Electrochemical deposition was performed using a three-electrode system. The electroplating current was set to -0.2 A and the electroplating time was 100 s. Under these conditions, zinc was uniformly deposited on the surface of the copper foil. After electroplating, the sample was rinsed with deionized water and anhydrous ethanol in sequence and then dried to obtain zinc-modified copper foil. S3, ammonia oxidation: The zinc-modified copper foil obtained in step S2 was placed in a 10 mM ammonia solution and soaked at room temperature for 4 h. Zinc oxide nanosheets were generated in situ on the zinc layer surface through a wet chemical oxidation reaction. After soaking, the sample was washed with deionized water and anhydrous ethanol and dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based current collector modified with zinc oxide nanosheets.

[0033] S4: Battery Assembly and Performance Testing The zinc oxide nanosheets modified with copper-based current collectors prepared in step S3 were die-cut into circular electrodes with a diameter of 16 mm. The electrodes were then transferred to a glove box filled with argon (H2O < 0.1 ppm, O2 < 0.1 ppm) and assembled with the positive electrode shell, negative electrode shell, separator (Celgard 2325 polypropylene separator), and electrolyte (1 M LiTFSI in DOL / DME (1:1 v / v) + 2wt% LiNO3) to form CR2032 type half-cells, symmetrical cells, and full cells. The electrochemical performance of the cells was then tested.

[0034] Example 6 The application of a zinc oxide nanosheet-modified copper-based current collector in lithium metal batteries specifically includes the following steps: The zinc oxide nanosheets modified with copper-based current collectors prepared in Example 3 were die-cut into circular electrodes with a diameter of 16 mm. The electrodes were then transferred to a glove box filled with argon (H2O < 0.1 ppm, O2 < 0.1 ppm) and assembled with a positive electrode shell, a negative electrode shell, a separator (Celgard 2325 polypropylene separator), and an electrolyte (1 M LiTFSI in DOL / DME (1:1 v / v) + 2 wt% LiNO3) to form CR2032 type half-cells, symmetrical cells, and full cells. The electrochemical performance of the cells was then tested.

[0035] Comparative Example 1: Preparation of zinc oxide modified copper-based current collectors using a traditional high-temperature heat treatment oxidation process, the steps of which are as follows: S1. Surface pretreatment: Commercially available planar copper foil with a thickness of 11 μm was cut into 4 cm × 4 cm pieces and immersed in 0.1 mol L⁻¹ solution. -1 Ultrasonic cleaning in dilute hydrochloric acid and acetone for 5 minutes, followed by drying to remove impurities, oil stains and oxide layer from the copper foil surface; S2, Copper foil with electroplated zinc layer: The copper foil pretreated in step S1 was placed in a 0.5 M zinc sulfate electrolyte. A three-electrode system was used for electrochemical deposition, with a platinum sheet as the counter electrode, the copper foil sample as the working electrode, and a saturated calomel electrode as the reference electrode. The electroplating current was set to -0.2 A and the electroplating time was 300 s. Under these conditions, zinc was uniformly deposited on the surface of the copper foil. After electroplating, the sample was rinsed with deionized water and anhydrous ethanol in sequence and then dried to obtain zinc-modified copper foil. S3': Heat treatment oxidation The zinc-modified copper foil obtained in step S2 is placed in a tube furnace and heated to 800°C at a heating rate of 5°C / min under an air atmosphere. It is held at that temperature for 1 hour and then naturally cooled to room temperature. The zinc layer is converted into zinc oxide through high-temperature oxidation to obtain a zinc oxide-modified copper-based current collector. S4: Battery Assembly and Performance Testing The zinc oxide-modified copper-based current collector prepared in step S3' was punched into a circular electrode with a diameter of 16 mm using a mold. The electrode was then transferred to a glove box filled with argon gas and assembled into a half-cell, a symmetrical cell, and a full cell with the positive electrode shell, negative electrode shell, separator, and electrolyte. The electrochemical performance of the battery was then tested.

[0036] Test Example 1: Electrochemical Performance Test (1) Symmetric cell test: at 0.5 mA cm -2 Constant current charge-discharge cycle tests were performed at a current density of 1 mAh cm⁻¹. -2 .

[0037] Test results are as follows Figure 9 As shown, the symmetric cell with zinc oxide nanosheets modified copper foil as the current collector (red curve) exhibits excellent cycle stability, with a cycle life exceeding 1600 h and small and stable voltage polarization (approximately ±0.02 V); when the current density is increased to 1 mA cm⁻¹... -2 Even under these conditions, the battery still maintains good cycle performance. In contrast, the voltage polarization of the symmetrical battery (black curve) with pure copper foil as the current collector is significantly increased (approximately ±0.04 V), indicating that the zinc oxide nanosheet modification layer effectively suppresses lithium dendrite growth and improves lithium deposition / dissolution behavior.

[0038] (2) Lithium deposition morphology analysis: The cycled battery was disassembled in a glove box, and the current collector was removed for SEM characterization. For example... Figure 8 As shown, the lithium deposition layer on the pure copper foil is about 17.14 μm thick and exhibits a loose and porous dendritic structure; while the lithium deposition layer on the zinc oxide nanosheet-modified copper foil is only about 9.14 μm thick and exhibits a dense and uniform morphology, further demonstrating the lithiophilicity of the zinc oxide modification layer and its guiding role in the uniform deposition of lithium.

[0039] Depend on Figure 6 As can be seen, the scanning electron microscope (SEM) image of the zinc oxide nanosheets modified on the copper foil surface prepared by the present invention, with a magnification scale bar of 500 nm, clearly shows that the three-dimensional porous zinc oxide nanosheets are uniformly distributed on the copper foil surface, and the nanosheets are interwoven to form a three-dimensional network structure with a pore size of about 210-250 nm.

[0040] Depend on Figure 8It can be seen that when pure copper foil is used as the current collector, the cross-sectional morphology of the lithium deposition layer is approximately 17.14 μm thick, exhibiting a loose and porous structure. When zinc oxide nanosheets are used to modify copper foil as the current collector, the cross-sectional morphology of the lithium deposition layer is approximately 9.14 μm thick, exhibiting a more dense and uniform structure, which clearly demonstrates the improvement effect of the zinc oxide modification layer on lithium deposition behavior.

[0041] Depend on Figure 9 It can be seen that when the current density is increased to 1 mA cm⁻¹ -2 Subsequently, the zinc oxide-modified current collector of the present invention still maintains stable cycling performance, proving that the material prepared by the present invention has excellent ability to suppress lithium dendrite growth and long-term cycling stability.

[0042] Comparative analysis of results: (1) High-temperature heat treatment (800℃) causes obvious thermal stress and lattice distortion in the copper foil substrate, resulting in a decrease in the mechanical properties of the material; (2) The thickness of the zinc oxide layer formed is uneven and lacks the three-dimensional porous nanosheet structure formed by the ammonia oxidation process of this invention; (3) Electrochemical performance tests show that the material prepared by heat treatment oxidation is not as good as the ammonia oxidation process of this invention in terms of suppressing lithium dendrite growth and cycle stability; (4) High-temperature process has high energy consumption, long production cycle, and high cost, which is not conducive to industrial production.

[0043] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A copper-based current collector modified with zinc oxide nanosheets, characterized in that, It includes a copper foil substrate and a three-dimensional porous zinc oxide nanosheet modification layer covering its surface; The zinc oxide nanosheet-modified copper-based current collector is obtained by using copper foil as raw material, which is zinc-plated and then oxidized on the surface with ammonia. The thickness of the substrate is 6-500 μm, the thickness of the zinc oxide nanosheet modification layer is 1-1.5 μm, and the pore size of the porous structure is 210-250 nm; the zinc oxide crystal phase is hexagonal wurtzite structure.

2. The method for preparing the zinc oxide nanosheet-modified copper-based current collector according to claim 1, characterized in that, Includes the following steps: S1. Surface pretreatment: Remove impurities and stains from the copper foil surface; S2, zinc-plated copper foil: zinc is electroplated onto the surface of the copper foil pretreated by S1 to deposit zinc on the copper foil surface. After washing and drying, zinc-modified copper foil is obtained. S3, Ammonia Oxidation: The zinc-modified copper foil from step S2 is placed in an ammonia solution for oxidation, generating zinc oxide nanosheets on the zinc layer surface, resulting in a copper-based current collector modified with zinc oxide nanosheets.

3. The preparation method according to claim 2, characterized in that, In step S1, the thickness of the copper foil is 6-500 μm.

4. The preparation method according to claim 2, characterized in that, In step S1, the surface pretreatment is as follows: the copper foil is first immersed in 0.1 mol L-1 dilute hydrochloric acid and sonicated for 5 min, then immersed in acetone and sonicated for 5 min, and then dried.

5. The preparation method according to claim 2, characterized in that, In step S2, the electroplating method is as follows: the copper foil pretreated in S1 is placed in zinc sulfate electrolyte, and then electroplating is performed using a platinum sheet as the counter electrode, the copper foil sample as the working electrode, and a saturated calomel electrode as the reference electrode.

6. The preparation method according to claim 5, characterized in that, In step S2, the concentration of the zinc sulfate solution is 0.01-1 M; the electroplating current is -0.2 A, and the electroplating time is 100-1000 s.

7. The preparation method according to claim 2, characterized in that, In step S2, the washing method is as follows: the surface of the copper foil after zinc deposition is rinsed sequentially with deionized water and anhydrous ethanol.

8. The preparation method according to claim 2, characterized in that, In step S3, the ammonia concentration is 10-30 mM, the oxidation temperature is room temperature, and the oxidation time is 2-12 h.

9. The application of a zinc oxide nanosheet-modified copper-based current collector as an electrode material for lithium batteries, characterized in that, The zinc oxide nanosheet-modified copper-based current collector is the zinc oxide nanosheet-modified copper-based current collector as described in claim 1 or the zinc oxide nanosheet-modified copper-based current collector prepared by the method described in any one of claims 2-8.

10. The application according to claim 9, characterized in that, The diameter of the electrode is 12-16 mm.

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