Sodium metal negative electrode material with three-dimensional gradient sodium-philic interface as well as preparation method and application of sodium metal negative electrode material

Abstract

The invention discloses a sodium metal negative electrode material with a three-dimensional gradient sodium-philic interface as well as a preparation method and application of the sodium metal negative electrode material, and belongs to the technical field of sodium metal batteries. According to the sodium metal negative electrode material and the preparation method thereof, a metal net is coated with sodium-philic metal with concentration gradient through an electro-deposition method, then the surface of the sodium metal is covered with the sodium-philic metal, and the sodium metal negative electrode with the three-dimensional gradient sodium-philic interface can be obtained; the metal sodium can be guided to realize uniform and compact deposition from bottom to top, the large specific surface area is beneficial to reducing the local current density, the sufficient space reserved by the metal grid can realize high-capacity sodium ion deposition, meanwhile, the volume expansion and the structure failure of the electrode are avoided, and finally, dendrite-free growth and excellent cycle life of the sodium metal negative electrode are realized. The preparation method has the characteristics of simple preparation process and low requirements on preparation environment.

Description

Technical Field

[0001] This invention belongs to the field of sodium metal battery technology, and specifically relates to a method for preparing and applying sodium metal anode material. Background Technology

[0002] With the rapid economic development and the surge in applications such as electric vehicles, portable devices, and wearable devices, the demand for efficient energy storage is constantly increasing. Currently, lithium-ion batteries are widely used due to their high energy density, low self-discharge rate, and long cycle life. However, the limited and uneven global distribution of lithium resources leads to the high cost of lithium-ion batteries. Sodium belongs to the same group as lithium, has similar chemical properties, and is abundant and inexpensive; therefore, sodium-ion batteries are considered a promising alternative to lithium-ion batteries.

[0003] Hard carbon has attracted attention as a negative electrode material for sodium-ion batteries due to its low cost and good rate performance, but its low specific capacity limits further improvement in battery energy density. In contrast, sodium metal anodes have extremely high theoretical specific capacity (approximately 1165 mAh·g). -1 Sodium metal batteries, with their low redox potential (-2.714 V vs. SHE), are an important development direction for the next generation of high-energy-density energy storage systems.

[0004] However, sodium metal anodes still face many challenges in practical applications. During cycling, uneven sodium ion flux distribution and significant volume expansion can lead to uneven and non-dense sodium deposition, which in turn induces sodium dendrite growth or the formation of "dead sodium." These problems can significantly reduce coulombic efficiency, shorten cycle life, and even cause internal short circuits in the battery, posing safety hazards.

[0005] To address these issues, researchers have proposed various strategies, including constructing three-dimensional current collectors, optimizing electrolyte systems, and conducting interface engineering. Among these, interface engineering, by constructing three-dimensional interfacial layers on the electrode surface, can effectively increase specific surface area, reduce local current density, and promote uniform sodium ion deposition, and has attracted widespread attention due to its ease of operation. However, most reported three-dimensional interfacial layers are currently homogeneous conductors, which, during rapid deposition, can lead to preferential sodium deposition at the top, resulting in volume expansion, induced dendrite growth, and ultimately, failure of the interface modification.

[0006] In the prior art, there have been some studies on the modification of the anode structure of sodium batteries. For example, invention patent CN120767309A discloses a strategy for constructing an artificial solid electrolyte interface (SEI) on the sodium surface. This involves coating a layer of nickel selenide powder onto the sodium metal surface using a rolling method. After resting, the nickel selenide spontaneously reacts to form sodium selenide and nickel (Na2Se / Ni). Na2Se has excellent sodium affinity, which can induce uniform sodium ion deposition, while metallic Ni has high mechanical strength, preventing dendrites from penetrating the artificial SEI. Although this method suppresses dendrite problems to some extent, the artificial SEI lacks sufficient space for sodium deposition, failing to meet the requirements for large sodium deposition amounts. Another example is invention patent CN115295792A, which provides a composite sodium metal anode material. This material uses a porous organic membrane as a framework, deposits an alloy-type conductive sodium-affinity layer (such as a nickel-phosphorus alloy) on the surface, and fills it with sodium metal through melting or pressing. This design utilizes a three-dimensional flexible framework to suppress volume expansion and promotes uniform sodium ion deposition through the sodium-affinity layer. However, the sodium-loving layer in this scheme still relies on a uniform, highly conductive alloy material, which fails to completely avoid the tendency of top deposition. Furthermore, its preparation process involves multiple complex steps, which is not conducive to large-scale preparation and cost control.

[0007] Therefore, although existing technologies have made some progress in the design of sodium battery anode structures, there is still a lack of an interface modification strategy that can effectively control sodium deposition behavior, suppress dendrite growth, and is simple to process and easy to scale up. Therefore, developing a novel three-dimensional interface sandwich that can adjust the sodium-affinity properties of the interface while ensuring good ion transport to achieve dense and uniform sodium deposition from bottom to top is of great significance for promoting the practical application of sodium metal batteries. Summary of the Invention

[0008] This invention addresses the technical problems in existing sodium metal battery anode materials, such as the tendency for top deposition in the 3D interface interlayer, leading to non-dense sodium deposition, volume expansion, dendrite formation, and interface failure. It proposes a sodium metal anode material with a three-dimensional gradient sodium-loving interface, its preparation method, and its applications.

[0009] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0010] This invention provides a method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, comprising the following steps:

[0011] The cleaned metal mesh precursor is placed in a prepared electrodeposition solution for electrodeposition. The resulting product is washed, dried, and then coated onto the sodium metal surface to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0012] The cleaning process involves using acetone, hydrochloric acid, deionized water, or ethanol; the metal mesh precursor is selected from any one of copper mesh, nickel mesh, and stainless steel mesh, with a mesh count of 200-500 mesh.

[0013] The solute in the electrodeposition solution is selected from at least one of SbCl3, SnCl4, BiCl3 and AgCl, and the solvent is ethanol or water, preferably an ethanol solution; the concentration of the electrodeposition solution is 0.001-5 mol / L. During the electrodeposition process, the higher the solution concentration, the larger the metal particles formed on the surface of the metal mesh, and vice versa.

[0014] The electrodeposition is performed under constant voltage or constant current conditions, wherein the constant voltage is -10 to -0.01 V and the constant current is 0.01 to 5 A cm⁻¹. -2 The electrodeposition time was 1-30 min, using a three-electrode system: a metal mesh as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. During electrodeposition, a longer deposition time resulted in a denser concentration of metal particles on the metal mesh surface, leading to a larger deposition amount. However, excessive deposition could cause severe volume expansion of the surface metal during sodium ion deposition / stripping, causing it to detach; conversely, insufficient deposition could weaken the sodium-affinity of the metal particles. Therefore, a suitable deposition amount was needed to balance sodium affinity and volume expansion. During electrodeposition, a non-conductive plastic film substrate was attached to the back of the metal mesh, allowing for rapid and uniform deposition on both sides of the mesh in the initial stages. As ions were consumed, the copper mesh facing the platinum sheet diffused faster under the influence of the electric field, resulting in a larger deposition amount. Conversely, the copper mesh facing away from the platinum sheet diffused more slowly due to substrate influence, resulting in less deposition and a concentration gradient.

[0015] The washing solution is a mixture of water and ethanol, and the drying temperature is 25-80℃;

[0016] The covering involves placing the side of the metal mesh with a high concentration of sodium-affinity metal onto the sodium metal surface. This creates a concentration gradient, with the high-concentration side at the bottom, guiding the uniform and dense deposition of sodium ions from bottom to top. Simultaneously, the metal mesh spontaneously alloys with the sodium upon contact, forming a sodium-metal alloy.

[0017] This invention provides a sodium metal anode material with a three-dimensional gradient sodium-loving interface prepared by the aforementioned preparation method.

[0018] This invention provides the application of the sodium metal anode material with a three-dimensional gradient sodium-loving interface in the preparation of sodium metal battery anodes.

[0019] The present invention also provides a sodium metal battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode is the sodium metal negative electrode material having a three-dimensional gradient sodium-loving interface.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention utilizes an electrodeposition method to coat a sodium-loving metal with a concentration gradient onto a metal mesh, and then coats it onto the surface of sodium metal, thus obtaining a sodium metal anode with a three-dimensional gradient sodium-loving interface. This solves the key problems of uneven and non-dense deposition, dendrite growth caused by volume expansion, and short cycle life of traditional metal anodes. This anode material has a three-dimensional gradient sodium-loving interface, which guides the uniform and dense deposition of sodium metal from bottom to top. The large specific surface area helps reduce local current density, and the ample space reserved in the metal mesh allows for high-capacity sodium ion deposition while avoiding electrode volume expansion and structural failure, ultimately achieving dendrite-free sodium metal anodes with excellent cycle life.

[0022] 2. The sodium metal anode with a three-dimensional gradient sodium-loving interface prepared by this invention achieves a current of 2 mA / cm². -2 Current density and deposition stripping 1 mA h / cm -2 Compared with the unmodified copper mesh anode material, the cycle life of the optimally modified metal anode material increased from 460h to 1060h, while the initial polarization decreased from 17.5mV to 9.8mV, resulting in a significant improvement in cycle life and a marked reduction in polarization voltage. This invention features a simple preparation process and low environmental requirements, which is of great significance for simplifying the preparation process of sodium metal anode materials and promoting their practical application. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The X-ray diffraction patterns of the sodium metal anode material prepared in Example 1 before and after electrodeposition are shown.

[0025] Figure 2 The image shows the characterization of the sodium metal anode material prepared in Example 1; where a is a scanning electron microscope image of copper@antimony; and b is a cross-sectional schematic diagram of copper@antimony covering the sodium metal surface.

[0026] Figure 3 The sodium metal anode materials prepared for Example 1 and Comparative Example 1 were tested at 6 mA cm⁻¹. -2 1mA cm -2 Scanning electron microscope image after 20 cycles under the specified conditions.

[0027] Figure 4 The time-voltage curves are for the sodium metal anode materials prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0031] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0032] XRD tests were performed on the sodium metal anode material prepared in this embodiment before and after copper mesh deposition. The results are as follows: Figure 1 As shown, the characteristic peaks of copper@antimony correspond to the standard cards for copper and antimony, proving that the copper mesh surface was successfully coated with antimony.

[0033] The sodium metal anode material prepared in this embodiment was analyzed by scanning electron microscopy, and the results are as follows: Figure 2 As shown, by Figure 2 It can be clearly seen that there is a gradient between copper and antimony; Figure 2 b is a schematic diagram of a cross-section of copper@antimony covering the surface of sodium metal, with the side with the higher concentration gradient facing the sodium metal.

[0034] Example 2

[0035] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0036] Prepare a 0.025 mol / L SnCl4 ethanol solution, and place a 6 cm² area... 2A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@tin was placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0037] Example 3

[0038] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0039] Prepare a 0.025 mol / L BiCl3 ethanol solution, and place a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@bismuth was placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0040] Example 4

[0041] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0042] Prepare a 0.025 mol / L AgCl ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@silver was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0043] Example 5

[0044] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0045] Prepare a 0.025 mol / L SbCl3 aqueous solution, and place a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0046] Example 6

[0047] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0048] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 30 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0049] Example 7

[0050] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0051] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 15 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0052] Example 8

[0053] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0054] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 1 min at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0055] Example 9

[0056] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0057] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -10V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0058] Example 10

[0059] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0060] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -0.01V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0061] Example 11

[0062] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0063] Prepare a 5 mol / L SbCl3 ethanol solution, and place a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0064] Example 12

[0065] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0066] Prepare a 0.001 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0067] Example 13

[0068] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0069] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh is placed in the above solution and heated at room temperature to 5A cm. -2 Under the conditions of constant current deposition for 6 min, after deposition, the material was washed in deionized water and ethanol respectively, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was placed on the surface of metallic sodium to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0070] Example 14

[0071] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0072] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution at room temperature at 0.01 Å cm⁻¹. -2 Under the conditions of constant current deposition for 6 min, after deposition, the material was washed in deionized water and ethanol respectively, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was placed on the surface of metallic sodium to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0073] Example 15

[0074] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0075] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 25℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0076] Example 16

[0077] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0078] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 80℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0079] Example 17

[0080] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0081] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 200-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0082] Example 18

[0083] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0084] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 500-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0085] Example 19

[0086] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0087] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh nickel mesh was placed in the above solution, and constant voltage electrodeposition was performed at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0088] Example 20

[0089] A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, the specific steps of which are as follows:

[0090] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh stainless steel mesh was placed in the above solution and subjected to constant voltage electrodeposition at -4.5V for 6 minutes at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of sodium metal to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

[0091] Comparative Example 1

[0092] A method for preparing a sodium metal anode material, the specific steps of which are as follows:

[0093] Sodium metal anode material is obtained by directly placing the cleaned copper mesh on the sodium metal surface.

[0094] Comparative Example 2

[0095] A method for preparing a sodium metal anode material, the specific steps of which are as follows:

[0096] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed on both sides of the copper mesh for 3 minutes at -4.5V at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of metallic sodium to obtain a sodium metal anode material.

[0097] Comparative Example 3

[0098] A method for preparing a sodium metal anode material, the specific steps of which are as follows:

[0099] Prepare a 0.025 mol / L SbCl3 ethanol solution. [The following appears to be a separate, unrelated sentence:] ...a 6 cm² area... 2 A 300-mesh copper mesh was placed in the above solution, and constant voltage electrodeposition was performed on both sides of the copper mesh for 6 minutes at -4.5V at room temperature. After deposition, the mesh was washed in deionized water and ethanol, and then dried in a vacuum drying oven at 60℃. The deposited copper@antimony was then placed on the surface of metallic sodium to obtain a sodium metal anode material.

[0100] Example of implementation effect 1

[0101] Sodium metal anode materials prepared using Examples 1-3, 7-8, and Comparative Examples 1-3 of this invention were assembled into sodium metal symmetric batteries, and battery performance was tested as follows:

[0102] A sodium metal anode was obtained by placing the high-concentration side of the deposited metal mesh on the surface of metallic sodium. Two identical sodium metal anodes with their low-concentration sides were then assembled face-to-face to form a symmetrical sodium metal battery for electrochemical performance testing. The button cell model was CR2032. The separator was made of glass fiber, and the electrolyte was 1 mol / L NaPF6 dissolved in ethylene glycol dimethyl ether. The assembled battery was left to stand for at least 8 hours.

[0103] The assembled batteries were subjected to rate performance and cycle performance tests, and the results are shown in Tables 1 and 2.

[0104] Table 1. Rate performance of batteries assembled from sodium metal anode materials prepared in Examples 1-3, 7-8, 20 and Comparative Examples 1-3.

[0105]

[0106] Table 2. Cycle performance of batteries assembled from sodium metal anode materials prepared in Examples 1-3, Example 7, and Comparative Examples 1-3.

[0107]

[0108] As shown in Tables 1 and 2, the sodium metal anode with gradient sandwich (Example 1) has a lower polarization voltage and longer cycle life compared to the sodium metal anode without gradient sandwich (Comparative Examples 2 and 3). This is because the gradient sandwich can induce uniform and dense deposition of sodium ions from bottom to top, while the absence of a gradient sandwich results in top deposition, leading to uneven and non-dense deposition. Figure 3 Deposition of different types of sodium-loving metals can produce similar effects. As shown in Tables 1 and 2, the gradient interface interlayer formed by antimony metal deposition exhibits superior performance, with lower polarization voltage and longer cycle life. Deposition conditions also have a certain influence on its deposition morphology and formation. For example, in Example 7, changing the deposition time to 15 minutes resulted in a lower polarization voltage at 6 mA cm⁻¹. -2 1 mAh cm -2 Under the given conditions, it can only cycle for 126 hours, while the optimal conditions in Example 1 can cycle for 534 hours under the same conditions.

[0109] in, Figure 3 a represents the sodium metal anode material prepared in Comparative Example 1 of this invention at 6 mA cm⁻¹. -2 1mA cm -2 Scanning electron microscope image after 20 cycles under the given conditions. Figure 3 b represents the sodium metal anode material prepared in Example 1 of this invention at 6 mA / cm². -2 1mA cm -2The scanning electron microscope image after 20 cycles under the given conditions clearly shows that the deposition in Example 1 is more uniform and dense.

[0110] Figure 4 The time-voltage curves of Example 1 and Comparative Example 1 of the present invention show that, compared with Comparative Example 1, the sodium metal anode material obtained in Example 1 exhibits better performance at 2 mA cm⁻¹. -2 1mA cm -2 Under these conditions, the initial polarization voltage was reduced from 16mV to 8mV, and the cycle life was increased from 460h to 1062h.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a sodium metal anode material with a three-dimensional gradient sodium-loving interface, characterized in that, Includes the following steps: The cleaned metal mesh precursor is placed in a prepared electrodeposition solution for electrodeposition. The resulting product is washed, dried, and then coated onto the sodium metal surface to obtain a sodium metal anode material with a three-dimensional gradient sodium-loving interface.

2. The preparation method according to claim 1, characterized in that: The cleaning process involves using acetone, hydrochloric acid, deionized water, or ethanol.

3. The preparation method according to claim 2, characterized in that: The metal mesh precursor is selected from any one of copper mesh, nickel mesh and stainless steel mesh, with a mesh count of 200-500 mesh.

4. The preparation method according to claim 3, characterized in that: The solute in the electrodeposition solution is selected from at least one of SbCl3, SnCl4, BiCl3 and AgCl, and the solvent is ethanol or water with a concentration of 0.001-5 mol / L.

5. The preparation method according to claim 4, characterized in that: The electrodeposition is performed under constant voltage or constant current conditions, wherein the constant voltage is -10 to -0.01 V and the constant current is 0.01 to 5 A cm⁻¹. -2 The electrodeposition time is 1-30 min.

6. The preparation method according to claim 5, characterized in that: The washing solution is a mixture of water and ethanol, and the drying temperature is 25-80℃.

7. The preparation method according to claim 6, characterized in that: The covering involves covering the sodium metal surface with the side of the metal mesh that has a high concentration of sodium-loving metal.

8. A sodium metal anode material with a three-dimensional gradient sodium-loving interface prepared by the preparation method according to any one of claims 1-7.

9. The application of the sodium metal anode material with a three-dimensional gradient sodium-loving interface as described in claim 8 in the preparation of sodium metal battery anodes.

10. A sodium metal battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, characterized in that: The negative electrode is the sodium metal negative electrode material with a three-dimensional gradient sodium-loving interface as described in claim 8.

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