A ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material and its preparation method and application

Abstract

The invention discloses a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material and a preparation method and application thereof. The preparation method comprises the following steps: preparing alumina nanorods and modifying them with sodium hydroxide; introducing lithiophilic Ti and Zr elements onto the surfaces of the surface-modified alumina nanorods by electrospinning to form a stable ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric; covering the fabric with graphite foil and subjecting the fabric to high-temperature carbonization to obtain the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material, which is used as a negative electrode material for a lithium metal battery, effectively inhibits dendrite growth and volume expansion of the lithium metal negative electrode, and improves the cycle life and rate performance of the battery; and assembling a half-cell using the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber negative electrode of the invention, effectively inhibiting dendrite growth of the lithium metal negative electrode, and improving the cycle life and rate performance of the battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, relates to lithium metal battery electrode materials, and specifically relates to a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material and a preparation method and application thereof. Background Art

[0002] With the rapid development of society and the continuous growth of global energy demand, the application of new energy vehicles, artificial intelligence devices, and smart energy storage grids has led to an increasingly urgent demand for batteries with high energy density, long life, and sustainability, especially in the fields of renewable energy and electric vehicles. Among various battery technologies, lithium metal batteries are favored for their advantages such as excellent theoretical capacity and low potential. However, in practical applications, lithium metal batteries still face some obstacles to overcome, such as solid electrolyte interface (SEI) instability and increased electrolyte consumption, which are often caused by the growth of lithium dendrites.

[0003] To overcome these problems, researchers are actively exploring various methods, such as electrolyte modification, functionalized separator modification, and structured negative electrode design, to inhibit the growth and volume expansion of lithium dendrites. Among them, by designing the lithium negative electrode structure using a three-dimensional carbon-based lithium-philic current collector, the problems of lithium dendrite growth and volume expansion in lithium metal batteries can be effectively overcome. However, traditional carbon-based materials have interfacial lithium repellency problems, which may hinder lithium nucleation and cause lithium metal agglomeration. Although precious metal nanoparticles, doping with other elements and other traditional alloys can improve the lithium repellency of electrodes, they are usually accompanied by additional side effects and high costs, which limit their widespread application. In addition, traditional carbon-based materials may have interfacial lithium repellency problems in lithium metal batteries, resulting in lithium agglomeration and uneven distribution, which in turn affects battery performance and life. Therefore, in response to the interfacial lithium repellency problem of carbon-based materials, researchers are actively developing new three-dimensional carbon-based lithium-philic current collector structures to solve the various challenges faced by lithium metal batteries during use. In recent years, nanocomposite fiber materials have attracted much attention as an emerging technology. Using a matrix such as metal or ceramic as the continuous phase, inorganic particles containing various elements are dispersed within the matrix through appropriate preparation methods. By combining these various elements, the desired performance can be achieved through unlimited combinations, while also achieving coordinated interactions between the multiple components. Therefore, the study of composite nanofiber-based lithium-free anode materials and composite electrodes has become an important direction for addressing the challenges of lithium metal batteries. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material and its preparation method and application, introduce materials containing Ti, Zr, and C into the surface of the Al2O3 three-dimensional skeleton, and use it as a negative electrode material for lithium metal batteries, effectively inhibiting the growth of lithium metal negative electrode dendrites and improving the cycle life and rate performance of the battery.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material comprises the following steps:

[0007] Step 1: Add 5-10 g of aluminum isopropoxide to 10-30 ml of water and stir until uniformly dispersed, then add 5-15 ml of acetic acid and continue stirring until the solution is clear. After freeze-drying and grinding, aluminum oxide nanorod powder is obtained;

[0008] Step 2: Disperse 150-300 mg of alumina nanorod powder in 20-40 ml of deionized water, then add 75-120 ml of a 2 mol / L sodium hydroxide aqueous solution to the mixture of the alumina nanorod powder and deionized water under stirring, continue stirring until uniform, and then collect the surface-modified alumina nanorods by centrifugation. The surface-modified alumina nanorods are then washed by centrifugation, dried, and ground to obtain the surface-modified alumina nanorods.

[0009] Step 3, ultrasonically dispersing 100-150 mg of the surface-modified alumina nanorods prepared in step 2 in 5-15 g of an acetic acid and ethanol mixed solution, then adding 0.2-1 g of polyvinyl pyrrolidone and stirring at 40-60 ° C for 5-12 hours, then adding 1-10 g of tetraisopropyl titanate in an ice water bath and stirring evenly, and then adding 0.2-1 g of zirconium acetate and stirring evenly to obtain an electrospinning suspension, spinning the suspension, weaving, and stabilizing it in a vacuum oven to form a stable ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric;

[0010] Step 4: Cut the ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric into strips with a length of 150 mm and a width of 30 mm. Each strip is covered with graphite foil and stacked on a square crucible. In an N2 atmosphere, heat it to 500-1500°C and maintain it for 0.5-3 h. After cooling it naturally to room temperature, take out the sample to obtain the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material after high-temperature carbonization.

[0011] The present invention also has the following technical features:

[0012] Preferably, the grinding in step 1 and step 2 is performed using a mortar for 20 to 30 minutes.

[0013] Preferably, the drying in step 2 is carried out in an oven at 80-100° C. for 8-12 hours.

[0014] Preferably, the mass ratio of acetic acid to ethanol in the acetic acid-ethanol mixed solution described in step three is 2:3.

[0015] Preferably, the spinning parameters in step 3 are as follows: the distance between the current collector and the stainless steel needle is 18 cm, the voltage, feed rate and distance are fixed at 25 kV and 1 mL / h respectively, and the humidity is 40% to 60%.

[0016] Preferably, in step three, the temperature of the ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric in the vacuum oven is set to be stable at 70-80°C for 8-10 hours.

[0017] The present invention also protects a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material prepared by the above method and its application in the negative electrode of a lithium metal battery.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] The present invention introduces lithiophilic Ti, Zr, and C elements on the surface of a three-dimensional Al2O3 main body by combining an electrospinning method with a high-temperature carbonization strategy. The Al2O3 fiber rod framework can reduce the local current density and slow down the volume expansion of lithium metal. The introduction of Ti, Zr, and C elements improves the lithiophilicity of the carbon substrate and reduces the nucleation potential of lithium. When used as a negative electrode material for lithium metal batteries, it effectively inhibits the growth and volume expansion of lithium metal negative electrode dendrites and improves the cycle life and rate performance of the battery. A half-cell is assembled using the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber negative electrode of the present invention. At a current density of 2 mA cm -2 , with a specific capacity of 1 mAh cm -2 The electrode stability was tested, and after 170 stable cycles, the average coulombic efficiency value was 98%. In addition, the anode-free HEA / CF||NCM811 full battery using the ZrO2 / Ti4O7-Al2O3 of the present invention had an initial capacity of 113.2 mAh g at 1C. -1 After 160 cycles, it still has 19 mAh g -1 , the CE was stably maintained at around 95.2% during the cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Flow chart of the folding resistance test of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1;

[0021] Figure 2 This is an SEM image of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1;

[0022] Figure 3 This is the EDS image of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1;

[0023] Figure 4 This is the XRD pattern of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1;

[0024] Figure 5 Electrochemical performance diagram of ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1;

[0025] Figure 6 This is the overpotential diagram of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1;

[0026] Figure 7 This is the full battery impedance diagram of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1;

[0027] Figure 8 DRT diagram of a half-cell of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free anode material prepared in Example 1;

[0028] Figure 9 This is a performance diagram of a full battery with ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1 at a current of 1C. DETAILED DESCRIPTION

[0029] The present invention will be described in detail below in conjunction with the accompanying drawings and Examples, but embodiments of the present invention are not limited thereto. The reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. The test methods in the following examples where specific experimental conditions are not specified are generally based on conventional experimental conditions. Unless otherwise specified, the reagents and raw materials used in the present invention can be obtained commercially.

[0030] Example 1

[0031] This embodiment provides a method for preparing a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material, which specifically includes the following steps:

[0032] Step 1: Add 5 g of aluminum isopropoxide to 18 ml of water and stir until uniformly dispersed, then add 9 ml of acetic acid and continue stirring until the solution is clear. After freeze-drying and grinding in a mortar for 30 minutes, aluminum oxide nanorod powder is obtained;

[0033] Step 2: 150 mg of alumina nanorod powder was dispersed in 30 ml of deionized water. Then, 100 mL of a 2 mol / L sodium hydroxide aqueous solution was added to the mixture of the alumina nanorod powder and deionized water under stirring. The mixture was stirred for 5 minutes until uniform, and the surface-modified alumina nanorods were collected by centrifugation. The mixture was further dispersed in 30 ml of deionized water, and the solid was collected by centrifugation. The solid was dried in an oven at 80° C. for 10 hours and ground in a mortar for 30 minutes to obtain the surface-modified alumina nanorods.

[0034] Step 3: ultrasonically disperse 100 mg of the surface-modified alumina nanorods prepared in step 2 in 11 g of an acetic acid and ethanol mixed solution, wherein the mass ratio of acetic acid to ethanol in the acetic acid and ethanol mixed solution is 2:3; then add 0.4 g of polyvinyl pyrrolidone and stir at 40 ° C for 10 h, then add 3 g of tetraisopropyl titanate in an ice water bath and stir evenly, then add 0.7 g of zirconium acetate and stir for 10 min until uniform to obtain an electrospinning suspension, and load the mixed suspension into a 20 ml syringe, set the distance between the collector and the stainless steel needle to 18 cm, and adjust the voltage and feed rate. The feed rate and distance were fixed at 25 kV and 1 mL / h, respectively, and the humidity was controlled at 40% for electrospinning. After spinning, the zirconium oxide / titania-alumina (ZrO2 / Ti4O7-Al2O3) composite nanofibers were separated from the release paper. Finally, the zirconium oxide / titania-alumina (ZrO2 / Ti4O7-Al2O3) composite nanofibers were stabilized in a vacuum oven at 70°C for 8 hours to form a stable ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric.

[0035] Step 4: Cut the ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric into strips 150 mm long and 30 mm wide, cover each strip with graphite foil, and stack them on a square crucible. After loading the sample and sealing the tube furnace test tube, heat it to 1000°C under N2 atmosphere and hold it for 1 hour. After cooling naturally to room temperature, take out the sample to obtain the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material after high-temperature carbonization;

[0036] During heating, a slow heating rate of 1K / min is used in the section from room temperature to 100°C to remove oxygen contamination; a faster heating rate of 2K / min is used in the section from 100°C to 300°C and from 700°C to 1000°C; and in the section from 300°C to 700°C, the heating rate is 1K / min.

[0037] The following tests were performed on the sample properties:

[0038] 1. Folding resistance and high temperature resistance

[0039] Figure 1 The above is a flow chart of the folding resistance test of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1. From the flow chart, it can be observed that the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber negative electrode material has good folding resistance;

[0040] Figure 1 The following is a flow chart for the high temperature resistance test of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1; it can be observed from the flow chart that the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material has good high temperature resistance.

[0041] 2 Morphology

[0042] Figure 2 This is an SEM image of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1. From the SEM image, it can be observed that the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber presents a three-dimensional network structure.

[0043] Figure 3 This is the EDS image of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1. Figure 3 It can be seen that Ti, Zr, and C are evenly distributed throughout the Al2O3 fiber.

[0044] 3 components

[0045] Figure 4 The XRD pattern of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1 is as follows: Figure 4 As shown, the three diffraction peaks of the X-ray diffraction (XRD) of the material correspond to the (111), (200) and (1-20) planes of the FCC phase, respectively.

[0046] 4 Electrochemical performance

[0047] Figure 5 The electrochemical performance diagram of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1; Figure 5 As shown in the figure, the negative electrode prepared in the embodiment is assembled into a half-cell and the current density is 2 mA cm -2 , with a specific capacity of 1 mAh cm -2The electrode stability was tested and an average coulombic efficiency value of 98% was obtained after 170 stable cycles.

[0048] Figure 6 This is the overpotential performance diagram of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1.

[0049] Figure 7 This is the full battery impedance diagram of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1; Figure 7 As shown, a full battery based on the negative electrode prepared in Example 1 and the NCM-811 positive electrode was assembled.

[0050] Figure 8 The DRT diagram of the half-cell of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1; Figure 8 As shown, DRT successfully distributes the electrochemical reaction process of lithium ions in the half-cell and the change pattern of impedance with the increase / decrease of lithium content. It can be determined that the four main peaks of the ZrO2 / Ti4O7-Al2O3 / C negative electrode at 10-4~10-2 (D1), 10-2~10-1 (D2), 10-1~1 (D3) and 1~100s (D4) show obvious and stable electrochemical processes, which correspond to: lithium ion transport process, SEI film formation and penetration process, lithium ion electronic reduction process, and lithium metal diffusion process.

[0051] Figure 9 The performance diagram of the full battery of ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material prepared in Example 1 at a current of 1C; Figure 9 As shown, the initial capacity of the full battery at 1C is 113.2 mAh g -1 After 160 cycles, it still has 19 mAh g -1 , the CE was stably maintained at around 95.2% during the cycle.

[0052] Example 2

[0053] This embodiment provides a method for preparing a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material, which specifically includes the following steps:

[0054] Step 1: Add 7 g of aluminum isopropoxide to 10 ml of water and stir until uniformly dispersed, then add 5 ml of acetic acid and continue stirring until the solution is clear. After freeze-drying and grinding in a mortar for 20 minutes, aluminum oxide nanorod powder is obtained;

[0055] Step 2: 200 mg of alumina nanorod powder was dispersed in 20 ml of deionized water. Then, 120 mL of a 2 mol / L sodium hydroxide aqueous solution was added to the mixture of the alumina nanorod powder and deionized water under stirring. The mixture was stirred for 5 minutes until uniform, and the surface-modified alumina nanorods were collected by centrifugation. The mixture was further dispersed in 30 ml of deionized water, and the solid was collected by centrifugation, dried in an oven at 100° C. for 8 hours, and ground in a mortar for 20 minutes to obtain surface-modified alumina nanorods.

[0056] Step 3: Ultrasonic disperse 120 mg of the surface-modified alumina nanorods prepared in step 2 in 5 g of an acetic acid and ethanol mixed solution, wherein the mass ratio of acetic acid to ethanol in the acetic acid and ethanol mixed solution is 2:3; then add 0.2 g of polyvinyl pyrrolidone and stir at 50 ° C for 5 h, then add 1 g of tetraisopropyl titanate in an ice water bath and stir evenly, then add 0.2 g of zirconium acetate and stir for 10 min until uniform to obtain an electrospinning suspension, and load the mixed suspension into a 20 ml syringe, set the distance between the collector and the stainless steel needle to 18 cm, and set the voltage and feed Electrospinning was performed at a fixed speed of 25 kV and a distance of 1 mL / h, respectively, and a humidity of 50%. After spinning, the ZrO2 / Ti4O7-Al2O3 composite nanofibers were separated from the release paper. Finally, the ZrO2 / Ti4O7-Al2O3 composite nanofibers were stabilized in a vacuum oven at 80°C for 9 hours to form a stable ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric.

[0057] Step 4: Cut the ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric into strips 150 mm long and 30 mm wide, cover each strip with graphite foil, and stack them on a square crucible. After loading the sample and sealing the tube furnace test tube, heat it to 500°C in a N2 atmosphere and hold it for 3 hours. After cooling naturally to room temperature, take out the sample to obtain the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material after high-temperature carbonization.

[0058] Example 3

[0059] This embodiment provides a method for preparing a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material, which specifically includes the following steps:

[0060] Step 1: Add 10 g of aluminum isopropoxide to 38 ml of water and stir until evenly dispersed, then add 15 ml of acetic acid and continue stirring until the solution is clear. Freeze-dry and grind in a mortar for 25 minutes to obtain aluminum oxide nanorod powder;

[0061] Step 2: 300 mg of alumina nanorod powder was dispersed in 40 ml of deionized water. Then, 75 mL of a 2 mol / L sodium hydroxide aqueous solution was added to the mixture of the alumina nanorod powder and deionized water under stirring. The mixture was stirred for 5 minutes until uniform, and the surface-modified alumina nanorods were collected by centrifugation. The mixture was further dispersed in 30 ml of deionized water, and the solid was collected by centrifugation, dried in a 90°C oven for 12 hours, and ground in a mortar for 25 minutes to obtain surface-modified alumina nanorods.

[0062] Step 3: ultrasonically disperse 150 mg of the surface-modified alumina nanorods prepared in step 2 in 15 g of an acetic acid and ethanol mixed solution, wherein the mass ratio of acetic acid to ethanol in the acetic acid and ethanol mixed solution is 2:3; then add 1 g of polyvinyl pyrrolidone and stir at 60 ° C for 12 h, then add 10 g of tetraisopropyl titanate in an ice water bath and stir evenly, then add 1 g of zirconium acetate and stir for 10 min until uniform to obtain an electrospinning suspension, and load the mixed suspension into a 20 ml syringe, set the distance between the collector and the stainless steel needle to 18 cm, and adjust the voltage and feed rate. The electrospinning was performed with the rate and distance fixed at 25 kV and 1 mL / h, respectively, and the humidity controlled at 60%. After the spinning was completed, the zirconium oxide / titania-alumina (ZrO2 / Ti4O7-Al2O3) composite nanofibers were separated from the release paper. Finally, the zirconium oxide / titania-alumina (ZrO2 / Ti4O7-Al2O3) composite nanofibers were stabilized in a vacuum oven at 75°C for 10 hours to form a stable ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric.

[0063] Step 4: Cut the ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric into strips 150 mm long and 30 mm wide, cover each strip with graphite foil, and stack them on a square crucible. After loading the sample and sealing the tube furnace test tube, heat it to 1500°C in a N2 atmosphere and hold it for 0.5 h. After cooling naturally to room temperature, take out the sample to obtain the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material after high-temperature carbonization.

[0064] Example 4

[0065] This embodiment provides a method for preparing a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material, which specifically includes the following steps:

[0066] Step 1: Add 6 g of aluminum isopropoxide to 18 ml of water and stir until uniformly dispersed, then add 9 ml of acetic acid and continue stirring until the solution is clear. After freeze-drying and grinding in a mortar for 30 minutes, aluminum oxide nanorod powder is obtained;

[0067] Step 2: 200 mg of alumina nanorod powder was dispersed in 30 ml of deionized water. Then, 100 mL of a 2 mol / L sodium hydroxide aqueous solution was added to the mixture of the alumina nanorod powder and deionized water under stirring. The mixture was stirred for 5 minutes until uniform, and then the surface-modified alumina nanorods were collected by centrifugation. The mixture was further dispersed in 30 ml of deionized water, and then the solid was collected by centrifugation, dried in an 80°C oven for 10 hours, and ground in a mortar for 30 minutes to obtain surface-modified alumina nanorods.

[0068] Step 3: ultrasonically disperse 100 mg of the surface-modified alumina nanorods prepared in step 2 in 11 g of an acetic acid and ethanol mixed solution, wherein the mass ratio of acetic acid to ethanol in the acetic acid and ethanol mixed solution is 2:3; then add 0.6 g of polyvinyl pyrrolidone and stir at 40 ° C for 10 h, then add 5 g of tetraisopropyl titanate in an ice water bath and stir evenly, then add 0.5 g of zirconium acetate and stir for 10 min until uniform electrospinning suspension is obtained, and the mixed suspension is loaded into a 20 ml syringe, and the distance between the collector and the stainless steel needle is set to 18 cm, and the voltage and feed rate are adjusted. The feed rate and distance were fixed at 25 kV and 1 mL / h, respectively, and the humidity was controlled at 40% for electrospinning. After spinning, the zirconium oxide / titania-alumina (ZrO2 / Ti4O7-Al2O3) composite nanofibers were separated from the release paper. Finally, the zirconium oxide / titania-alumina (ZrO2 / Ti4O7-Al2O3) composite nanofibers were stabilized in a vacuum oven at 70°C for 8 hours to form a stable ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric.

[0069] Step 4: Cut the ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric into strips 150 mm long and 30 mm wide, cover each strip with graphite foil, and stack them on a square crucible. After loading the sample and sealing the tube furnace test tube, heat it to 1200°C in a N2 atmosphere and hold it for 1 hour. After cooling naturally to room temperature, take out the sample to obtain the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber lithium-free negative electrode material after high-temperature carbonization.

[0070] It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it; without departing from the concept of the present invention, the deduction or replacement made by those skilled in the art shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing a ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material, characterized in that: The following steps are involved: Step 1: Add 5-10 g of aluminum isopropoxide to 10-30 ml of water and stir until uniformly dispersed, then add 5-15 ml of acetic acid and continue stirring until the solution is clear. After freeze-drying and grinding, aluminum oxide nanorod powder is obtained; Step 2: Disperse 150-300 mg of alumina nanorod powder in 20-40 ml of deionized water, then add 75-120 ml of a 2 mol / L sodium hydroxide aqueous solution to the mixture of the alumina nanorod powder and deionized water under stirring, continue stirring until uniform, and then collect the surface-modified alumina nanorods by centrifugation. The surface-modified alumina nanorods are then washed by centrifugation, dried, and ground to obtain the surface-modified alumina nanorods. Step 3, ultrasonically dispersing 100-150 mg of the surface-modified alumina nanorods prepared in step 2 in 5-15 g of an acetic acid and ethanol mixed solution, then adding 0.2-1 g of polyvinyl pyrrolidone and stirring at 40-60 ° C for 5-12 hours, then adding 1-10 g of tetraisopropyl titanate in an ice water bath and stirring evenly, and then adding 0.2-1 g of zirconium acetate and stirring evenly to obtain an electrospinning suspension, spinning the suspension, weaving, and stabilizing it in a vacuum oven to form a stable ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric; Step 4: Cut the ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric into strips with a length of 150 mm and a width of 30 mm. Each strip is covered with graphite foil and stacked on a square crucible. In an N2 atmosphere, heat it to 500-1500°C and maintain it for 0.5-3 h. After cooling it naturally to room temperature, take out the sample to obtain the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material after high-temperature carbonization.

2. The method for preparing the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material according to claim 1, characterized in that: The grinding in step 1 and step 2 is performed using a mortar for 20 to 30 minutes.

3. The method for preparing the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material according to claim 1, characterized in that: The drying in step 2 is carried out in an oven at 80-100° C. for 8-12 hours.

4. The method for preparing the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material according to claim 1, characterized in that: The mass ratio of acetic acid to ethanol in the acetic acid-ethanol mixed solution described in step 3 is 2:

3.

5. The method for preparing the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material according to claim 1, characterized in that: The spinning parameters described in step 3 are as follows: the distance between the current collector and the stainless steel needle is 18 cm, the voltage, feed rate and distance are fixed at 25 kV and 1 mL / h respectively, and the humidity is 40% to 60%.

6. The method for preparing the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material according to claim 1, characterized in that: In step 3, the ZrO2 / Ti4O7-Al2O3 composite nanofiber fabric is stabilized in a vacuum oven at a temperature of 70-80°C for 8-10 hours.

7. A ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material prepared by the method according to any one of claims 1 to 6.

8. Use of the ZrO2 / Ti4O7-Al2O3 / C composite nanofiber material as claimed in claim 7 in a negative electrode of a lithium metal battery.

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