A sodium titanate nanofiber / reduced graphene oxide composite electrode material, a preparation method therefor, and an application thereof

Abstract

The application relates to a sodium titanate nanofiber / reduced graphene oxide composite electrode material and a preparation method and application thereof. The composite electrode material has a two-dimensional sheet structure, the particle size is 1-6 mu m, the thickness is 10-20 nm, is composed of a few-layer reduced graphene oxide and sodium titanate nanofibers with a diameter of 5-10 nm loaded on the reduced graphene oxide, and is prepared by taking the few-layer reduced graphene oxide as a template, uniformly loading titanium dioxide particles, and then carrying out hydrothermal treatment in an alkali solution. Compared with the prior art, the synthesis method is simple in process, easy to scale up, and high in controllability. As a negative electrode of a sodium ion battery or a positive electrode of a sodium battery, the sodium titanate nanofiber / reduced graphene oxide composite electrode material has the advantages of high initial coulomb efficiency, low working voltage, high capacity, excellent rate characteristics and cycle stability, and has a broad market application prospect.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery electrode materials technology, specifically to a sodium titanate nanofiber / reduced graphene oxide composite electrode material, its preparation method, and its application. Background Technology

[0002] Sodium-ion batteries possess the advantages of abundant resources and low cost, highlighting their enormous natural potential in applications such as large-scale energy storage and smart grids. However, their energy density, power density, and long-cycle stability remain shortcomings in their practical development and require further improvement.

[0003] Anode materials play a crucial role in the energy density and stability of batteries. The ideal anode material should possess a low discharge voltage and a high theoretical capacity. Simultaneously, first-cycle coulombic efficiency, power characteristics, and cycle stability are also important performance indicators. Titanium-based anode materials have attracted considerable interest due to their high sodium storage activity, high stability, low cost, and non-toxicity. Among them, Na₂Ti₃O₇ has a relatively high theoretical capacity (310 mAh g⁻¹). -1 and a lower discharge voltage plateau (0.3V vs Na / Na) + This can lead to higher operating voltages and energy densities in practical batteries. However, due to the large band gap (3.7 eV) of Na2Ti3O7 material itself, it exhibits slow sodium ion insertion / extraction kinetics. Furthermore, the large number of sodium insertions in the Na2Ti3O7 lattice causes severe structural strain, exposing more reactive surface sites, leading to continuous electrolyte decomposition and resulting in a low first-cycle coulombic efficiency, thus exhibiting poor cycling stability.

[0004] Existing literature mainly addresses the above problems by designing nanoparticle structures (Adv. Mater. 2017, 29, 1700989) and surface doping (Adv. Energy Mater. 2016, 6, 1502568), but these strategies have limited effect on improving ion transport. Summary of the Invention

[0005] The purpose of this invention is to provide a sodium titanate nanofiber / reduced graphene oxide composite electrode material, its preparation method and application, to improve ion transport rate.

[0006] The objective of this invention can be achieved through the following technical solution: a sodium titanate nanofiber / reduced graphene oxide composite electrode material, having a two-dimensional sheet structure, a particle size of 1-6 μm, a thickness of 10-20 nm, and composed of few-layer reduced graphene oxide and sodium titanate nanofibers with a diameter of 5-10 nm loaded thereon.

[0007] Preferably, the mass of the few-layer reduced graphene oxide is 10%-20% of the mass of the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0008] The sodium titanate nanofiber / reduced graphene oxide composite material of the present invention is prepared by using few-layer reduced graphene oxide as a template, uniformly loading titanium dioxide particles, and then hydrothermally treating it in an alkaline solution.

[0009] The sodium titanate nanofiber / reduced graphene oxide composite material of the present invention is obtained by solvent synthesis of titanium oxide, loading it onto few-layer reduced graphene oxide to form a precursor, and then treating it with an alkaline solution. The composite material has a two-dimensional sheet structure with a particle size of about 3 μm and a thickness of about 10-20 nm. It is composed of few-layer reduced graphene oxide and sodium titanate nanofibers with a diameter of 5-10 nm loaded on it.

[0010] A method for preparing the above-mentioned sodium titanate nanofiber / reduced graphene oxide composite electrode material includes the following steps:

[0011] (1) Solvent method for synthesizing precursors: few-layer reduced graphene oxide was added to an organic solvent with a strong base, stirred vigorously, and then titanium source was added. The solvent was dried to obtain a mixture of graphene-supported titanium dioxide. The black precipitate was collected, dried, and calcined to obtain the rGO / TiO2 composite precursor.

[0012] (2) Preparation of sodium titanate nanofiber / reduced graphene oxide composite electrode material by hydrothermal treatment: The precursor obtained in step (1) was added to sodium hydroxide alkaline solution, and then hydrothermally treated in a reaction vessel. After washing and drying, sodium titanate nanofiber / reduced graphene oxide composite electrode material was obtained.

[0013] Preferably, in step (1), the titanium source is one or more of titanium sulfate, titanium tert-butoxide, titanium methoxy, titanium tetrachloride, tetrabutyl titanate, isopropyl titanate, tetraethyl titanate, or titanium acetylacetonate.

[0014] Preferably, in step (1), the strong alkali is one or more of ammonia, quaternary ammonium alkali, sodium hydroxide, potassium hydroxide, and calcium hydroxide.

[0015] Preferably, in step (1), the organic solvent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, benzene, toluene, diethyl ether, tetrahydrofuran, chloroform, or dichloromethane.

[0016] Preferably, in step (2), the concentration of the sodium hydroxide alkaline solution is 1-20M.

[0017] An application of the above-mentioned sodium titanate nanofiber / reduced graphene oxide composite electrode material is to use the composite electrode material to prepare sodium-ion batteries or sodium batteries.

[0018] Preferably, the sodium titanate nanofiber / reduced graphene oxide composite material is used as the negative electrode of a sodium-ion battery or the positive electrode of a sodium battery.

[0019] Preferably, in the sodium-ion battery, the sodium titanate nanofiber / reduced graphene oxide composite electrode material is the negative electrode, and the sodium-ion intercalating / deintercalating active material is the positive electrode.

[0020] Preferably, in the sodium battery, the sodium titanate nanofiber / reduced graphene oxide composite electrode material is the positive electrode, and metallic sodium is the negative electrode.

[0021] Preferably, the sodium-ion battery and sodium battery are rechargeable room-temperature sodium / sodium-ion batteries, including a positive electrode, a negative electrode, an electrolyte, a separator, and a casing; in the sodium-ion battery, the sodium titanate nanofiber / reduced graphene oxide composite electrode material is the negative electrode, and the sodium-ion intercalation / deintercalation active material is the positive electrode; in the sodium battery, the sodium titanate nanofiber / reduced graphene oxide composite electrode material is the positive electrode, and metallic sodium is the negative electrode.

[0022] More preferably, the diaphragm is a glass fiber diaphragm, a polyethylene microporous membrane, a polypropylene microporous membrane, or a composite diaphragm thereof, and the electrolyte is a soluble sodium salt organic solution.

[0023] More preferably, the sodium-ion battery or sodium battery electrolyte—a soluble sodium salt organic solution—is obtained by dissolving a sodium salt in an organic solvent. The sodium salt is one or more of sodium hexafluorophosphate, sodium perchlorate, sodium trifluoromethanesulfonate, and sodium nitrate. The organic solvent is one or more of ethylene carbonate, propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-cyclopentanediol, ethylene glycol dimethyl ether, and triethylene glycol dimethyl ether.

[0024] More preferably, the sodium-intercalating / deintercalating active material includes transition metal oxides, phosphates, pyrophosphates, sulfates, and fluorophosphates.

[0025] Preferably, the sodium battery positive electrode sheet is obtained by coating a slurry, which is obtained by uniformly mixing the positive electrode material with a conductive agent, a binder, and a dispersant, onto a current collector, and the current collector is a copper foil; the sodium-ion battery negative electrode sheet is obtained by coating a slurry, which is obtained by uniformly mixing the negative electrode material with a conductive agent, a binder, and a dispersant, onto a current collector, and the positive electrode sheet is obtained by coating a slurry, which is obtained by uniformly mixing the positive electrode material with a conductive agent, a binder, and a dispersant, onto a current collector, and the current collector is an aluminum foil.

[0026] More preferably, the sodium-ion battery or sodium battery conductive agent is one or more of acetylene black, Super P or graphite; the binder is one or more of polytetrafluoroethylene, polyvinylidene fluoride or styrene-butadiene rubber; and the dispersant is one or more of anhydrous ethanol, isopropanol or 1-methyl-2-pyrrolidone.

[0027] Preferably, the outer casing of the battery is made of aluminum, aluminum-plastic film (soft-pack battery), stainless steel, or their composite materials, and the shape is button-type, cylindrical, or square.

[0028] The sodium titanate nanofiber / reduced graphene oxide composite electrode material of this invention has a one-dimensional ultrafine sodium titanate nanofiber structure. The synthesis method is simple, easy to scale up, and highly controllable. As a negative electrode or positive electrode of sodium-ion batteries, it has the advantages of high first-cycle coulombic efficiency, low operating voltage, high capacity, excellent rate performance and cycle stability, showing broad market application prospects.

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

[0030] 1. This invention utilizes a rationally designed nanostructure of sodium titanate material, employing a one-dimensional fiber structure, to obtain a material with high first-cycle coulombic efficiency, high capacity, excellent rate performance, and cycling stability.

[0031] 2. The one-dimensional sodium titanate nanofibers in the bulk structure of this invention can effectively shorten the ion transport path, increase the ion transport rate, and release more sodium storage sites. At the same time, the few-layer reduced graphene oxide substrate can effectively improve the electronic conductivity, thereby effectively improving the sodium storage performance of the sodium titanate nanofibers.

[0032] 3. The composite electrode material of this invention has excellent kinetic characteristics, high actual reversible capacity, high first-cycle coulombic efficiency, and excellent cycle stability. Rechargeable sodium-ion batteries or sodium batteries containing this material have the advantages of high energy density and power density, showing broad market application prospects.

[0033] 4. The preparation process of this invention is simple, easy to scale up for production, and highly controllable. The diameter, specific surface area, and mesoscopic structure of the obtained sodium titanate nanofibers can all be adjusted. Attached Figure Description

[0034] Figure 1 This is the XRD pattern of the rGO / titanium dioxide precursor prepared in Example 1;

[0035] Figure 2 This is a TEM image of the rGO / titanium dioxide precursor prepared in Example 1;

[0036] Figure 3This is the XRD pattern of the sodium titanate nanofiber / reduced graphene oxide composite electrode material prepared in Example 1;

[0037] Figure 4 This is a TEM image of the sodium titanate nanofiber / reduced graphene oxide composite electrode material prepared in Example 1;

[0038] Figure 5 This is a TEM image of the sodium titanate nanofiber / reduced graphene oxide composite electrode material prepared in Example 1;

[0039] Figure 6 This is an HRTEM image of the sodium titanate nanofiber / reduced graphene oxide composite electrode material prepared in Example 1;

[0040] Figure 7 This is a charge-discharge curve of the sodium battery prepared in Example 1;

[0041] Figure 8 This is a rate performance diagram of the sodium battery prepared in Example 1;

[0042] Figure 9 This is a cycling diagram of the sodium battery prepared in Example 1 at a specific current density. Detailed Implementation

[0043] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0044] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0045] Example 1

[0046] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0047] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution, treated in a reactor at 150 °C for 24 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0048] Figure 1 The image shows the XRD pattern of the precursor rGO / titanium dioxide, which corresponds to the standard card (PDF#21-1272) of anatase-type TiO2. It can be seen that it is pure phase titanium dioxide. Figure 2 The image shows a TEM image of the precursor rGO / titanium dioxide, which reveals that titanium dioxide nanoparticles are loaded onto two-dimensional few-layer reduced graphene oxide sheets. Figure 3 The image shows the X-ray diffraction (XRD) pattern of the sodium titanate nanofiber / reduced graphene oxide composite material, with some crystal planes corresponding to the standard card (PDF#31-1329). The diffraction peak (2theta = 8.5°) corresponds to the (001) crystal plane and exhibits the highest intensity, indicating that the (001) crystal plane is the dominant crystal plane of sodium titanate. Figure 4 The image shows a TEM image of a sodium titanate nanofiber / reduced graphene oxide composite material, which can be seen to be sheet-like particles with a length of about 3 μm. Figure 5 The image shows a TEM image of a sodium titanate nanofiber / reduced graphene oxide composite material. It can be seen that sodium titanate nanofibers with a diameter of 5-10 nm are arranged on two-dimensional reduced graphene oxide sheets, with an overall thickness of 10-20 nm. Figure 6 The image shows a high-magnification TEM image of the sodium titanate nanofiber / reduced graphene oxide composite material. It can be seen that the sodium titanate nanofibers are located on the reduced graphene oxide sheets, with a lattice spacing of approximately 0.84 nm, corresponding to its (001) crystal plane. The mass of the few-layer reduced graphene oxide accounts for 12.0% of the total mass of the sodium titanate nanofiber / reduced graphene oxide composite material.

[0049] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge within a potential range of 0.01-3.0V at room temperature. Its charge-discharge curve and rate performance are shown below. Figure 7 and Figure 8 As shown. At 0.2C, the discharge plateau is less than 1.0V, with a specific capacity reaching 268.2 mAh / g, while also exhibiting a high first-cycle coulombic efficiency of 85.4%. At 80C, its discharge specific capacity reaches 81.1 mAh / g (1C = 310 mA / g). Its cycle stability is as follows... Figure 9 As shown, after 2000 cycles at 5.0C, it still retains a reversible capacity of 150.8 mAh / g, with a capacity retention of 83.3%.

[0050] Example 2

[0051] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0052] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution, treated in a reactor at 150 °C for 24 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0053] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. A 1M NaClO4 solution dissolved in EC:DEC (volume ratio 1:1) was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0054] Example 3

[0055] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0056] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution and treated in a reactor at 150 °C for 24 hours. After washing with ethanol and water, it was dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0057] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. A 1M NaPF6 solution dissolved in EC:DMC (volume ratio 1:1) was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0058] Example 4

[0059] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0060] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution, treated in a reactor at 150 °C for 24 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0061] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaPF6 dissolved in DME was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0062] Example 5

[0063] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0064] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution, treated in a reactor at 150 °C for 24 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0065] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the negative electrode active material. The negative electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. Commercially available sodium vanadium fluorophosphate was used as the positive electrode active material. The positive electrode active material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 70:20:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto aluminum foil. After vacuum drying at 80℃, negative and positive electrode sheets with a diameter of 13 mm were obtained. A glass fiber membrane (Whatman GF / D) was used as the separator, and 1M NaPF6 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium-ion batteries assembled using the above process were tested for charge and discharge at room temperature within a potential range of 0.1-3.0V.

[0066] Example 6

[0067] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0068] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution, treated in a reactor at 150 °C for 24 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0069] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the negative electrode active material. The negative electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. Commercially available sodium vanadium phosphate was used as the positive electrode active material. The positive electrode active material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 70:20:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto lv2 foil. After vacuum drying at 80℃, negative and positive electrode sheets with a diameter of 13 mm were obtained. A glass fiber membrane (Whatman GF / D) was used as the separator, and 1M NaPF6 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium-ion batteries assembled using the above process were tested for charge and discharge at room temperature within a potential range of 0.1-3.0V.

[0070] Example 7

[0071] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0072] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution, treated in a reactor at 150 °C for 24 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0073] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the negative electrode active material. The negative electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. Commercially available sodium vanadium fluorophosphate was used as the positive electrode active material. The positive electrode active material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 70:20:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto lv2 foil. After vacuum drying at 80℃, negative and positive electrode sheets with a diameter of 13 mm were obtained. A glass fiber membrane (Whatman GF / D) was used as the separator, and 1M NaClO4 dissolved in EC:DEC (volume ratio 1:1) was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium-ion batteries assembled using the above process were tested for charge and discharge at room temperature within a potential range of 0.1-3.0V.

[0074] Example 8

[0075] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0076] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution, treated in a reactor at 150 °C for 24 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0077] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the negative electrode active material. The negative electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. Commercially available sodium vanadium phosphate was used as the positive electrode active material. The positive electrode active material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 70:20:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto lv2 foil. After vacuum drying at 80℃, negative and positive electrode sheets with a diameter of 13 mm were obtained. A glass fiber membrane (Whatman GF / D) was used as the separator, and 1M NaClO4 dissolved in EC:DEC (volume ratio 1:1) was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium-ion batteries assembled using the above process were tested for charge and discharge at room temperature within a potential range of 0.1-3.0V.

[0078] Example 9

[0079] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0080] 0.5 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution and treated in a reactor at 150 °C for 24 hours. After washing with ethanol and water, and drying in an oven, the sodium titanate nanofiber / reduced graphene oxide composite electrode material was obtained.

[0081] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0082] Example 10

[0083] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0084] 2.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution and treated in a reactor at 150 °C for 24 hours. After washing with ethanol and water, it was dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0085] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0086] Example 11

[0087] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0088] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 50 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution and treated in a reactor at 150 °C for 24 hours. After washing with ethanol and water, and drying in an oven, the sodium titanate nanofiber / reduced graphene oxide composite electrode material was obtained.

[0089] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0090] Example 12

[0091] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0092] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 200 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution and treated in a reactor at 150 °C for 24 hours. After washing with ethanol and water, and drying in an oven, the sodium titanate nanofiber / reduced graphene oxide composite electrode material was obtained.

[0093] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0094] Example 13

[0095] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0096] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 450 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution and treated in a reactor at 150 °C for 24 hours. After washing with ethanol and water, and drying in an oven, the sodium titanate nanofiber / reduced graphene oxide composite electrode material was obtained.

[0097] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0098] Example 14

[0099] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0100] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 550 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution and treated in a reactor at 150 °C for 24 hours. After washing with ethanol and water, it was dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0101] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0102] Example 15

[0103] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0104] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 5 M sodium hydroxide solution and treated in a reactor at 150 °C for 24 hours. After washing with ethanol and water, and drying in an oven, the sodium titanate nanofiber / reduced graphene oxide composite electrode material was obtained.

[0105] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0106] Example 16

[0107] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0108] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 20 M sodium hydroxide solution, treated in a reactor at 150 °C for 24 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0109] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0110] Example 17

[0111] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0112] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution, treated in a reactor at 150 °C for 12 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0113] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0114] Example 18

[0115] The synthesis steps of the sodium titanate nanofiber / reduced graphene oxide composite electrode material used in this invention are as follows:

[0116] 1.0 mL of NH4OH was added to 50 mL of anhydrous ethanol solution. After stirring for 10 minutes, 100 mg of graphene oxide was added, and stirring was continued for another 10 minutes to mix thoroughly. Then, 3.0 g of tetrabutyl titanate (TBOT) was added dropwise. The entire solution was heated in an oil bath at 60 °C for 6 hours with stirring at 400 rpm, and then cooled to room temperature. The black precipitate was separated and collected by centrifugation, washed with ethanol, and dried in an oven. Finally, it was calcined at 350 °C for 3 hours under a nitrogen atmosphere to obtain the rGO-supported titanium dioxide precursor. 0.15 g of this precursor was added to 30 mL of 10 M sodium hydroxide solution, treated in a reactor at 150 °C for 48 hours, washed with ethanol and water, and dried in an oven to obtain the sodium titanate nanofiber / reduced graphene oxide composite electrode material.

[0117] The prepared sodium titanate nanofiber / reduced graphene oxide composite electrode material was used as the positive electrode active material. The positive electrode material was mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 80:10:10, using 1-methyl-2-pyrrolidone as a dispersant. The mixture was thoroughly mixed to form a slurry and then coated onto copper foil. After vacuum drying at 80℃, a 13mm diameter positive electrode sheet was obtained. A sodium metal sheet (16mm diameter) was used as the negative electrode, and a glass fiber membrane (Whatman GF / D) was used as the separator. 1M NaSO3CF3 dissolved in DGM was used as the electrolyte. A stainless steel shell was used as the outer casing, and the cells were assembled into a CR2025 button cell. The sodium battery assembled in the above process was tested for charge and discharge at room temperature within a potential range of 0.01-3.0V.

[0118] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A sodium titanate nanofiber / reduced graphene oxide composite electrode material, characterized in that, It has a two-dimensional sheet structure with a particle size of 1-6 μm and a thickness of 10-20 nm. It consists of few-layer reduced graphene oxide and sodium titanate nanofibers with a diameter of 5-10 nm supported on it. The sodium titanate nanofiber / reduced graphene oxide composite electrode material is prepared by uniformly loading titanium dioxide particles onto a few-layer reduced graphene oxide template and then hydrothermally treating it in an alkaline solution. The sodium titanate nanofiber / reduced graphene oxide composite electrode material was prepared by the following method: (1) Synthesizing precursors by solvent method: few-layer reduced graphene oxide was added to an organic solvent with a strong base, stirred and then titanium source was added. The solvent was dried to obtain a mixture of graphene-supported titanium dioxide. The precipitate was collected, dried, and calcined to obtain rGO / TiO2 composite precursor. (2) Sodium titanate nanofiber / reduced graphene oxide composite electrode material was prepared by hydrothermal treatment: The precursor obtained in step (1) was added to sodium hydroxide alkaline solution, followed by hydrothermal treatment, washing and drying to obtain sodium titanate nanofiber / reduced graphene oxide composite electrode material. The mass of the few-layer reduced graphene oxide is 10%-20% of the mass of the sodium titanate nanofiber / reduced graphene oxide composite electrode material. The concentration of the sodium hydroxide alkaline solution is 1-20M; The calcination process involves heating to 300-800℃ at a rate of 1-5℃ / min and holding at that temperature for 0.5-3 hours.

2. The sodium titanate nanofiber / reduced graphene oxide composite electrode material according to claim 1, characterized in that, In step (1), the titanium source is one or more of titanium sulfate, titanium tert-butoxide, titanium methoxy, titanium tetrachloride, tetrabutyl titanate, isopropyl titanate, tetraethyl titanate, or titanium acetylacetonate.

3. The sodium titanate nanofiber / reduced graphene oxide composite electrode material according to claim 1, characterized in that, In step (1), the strong base is one or more of ammonia, quaternary ammonium base, sodium hydroxide, potassium hydroxide, and calcium hydroxide; the organic solvent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, benzene, toluene, diethyl ether, tetrahydrofuran, chloroform, or dichloromethane.

4. An application of the sodium titanate nanofiber / reduced graphene oxide composite electrode material as described in any one of claims 1 to 3, characterized in that, The composite electrode material described above is used to prepare sodium-ion batteries or sodium batteries.

5. The application of the sodium titanate nanofiber / reduced graphene oxide composite electrode material according to claim 4, characterized in that, In the sodium-ion battery described above, the sodium titanate nanofiber / reduced graphene oxide composite electrode material is the negative electrode, and the active material capable of intercalating / deintercalating sodium ions is the positive electrode.

6. The application of the sodium titanate nanofiber / reduced graphene oxide composite electrode material according to claim 4, characterized in that, In the sodium battery described above, sodium titanate nanofiber / reduced graphene oxide composite electrode material is used as the positive electrode, and metallic sodium is used as the negative electrode.

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