Preparation method and application of carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material

Abstract

The present invention relates to the technical field of lithium-ion battery negative electrode materials, and in particular to a preparation method and application of a carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material. The method comprises the following steps: placing a conductive substrate in a mixed solution A for a solvothermal reaction, followed by heat treatment to obtain a carbon nanotube array containing a metal catalyst; immersing the carbon nanotube array containing the metal catalyst in a mixed solution B to obtain a carbon nanotube array from which the catalyst has been removed; and adding the carbon nanotube array from which the catalyst has been removed to a mixed solution C for a solvothermal reaction, followed by heat treatment to obtain a carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material. The method significantly accelerates the electrode reaction kinetics of TNO. When the carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material prepared by the present invention is used as an electrode material for a lithium-ion battery negative electrode material, it exhibits a high capacity and a long cycle life.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery negative electrode materials, and in particular to a preparation method and application of a carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material. Background Art

[0002] The development of next-generation energy storage materials with fast charge and discharge capabilities is of direct significance to accelerating the popularization of electric vehicles. Anode materials are key components that determine the high-rate performance of lithium-ion batteries. Currently commercialized graphite anodes have poor performance in terms of stability, safety, and fast charge and discharge. Titanium niobium oxide (TNO, such as TiNb2O7, Ti2Nb 10 O 29 Anode materials exhibit low volume expansion during lithium insertion and extraction, superior safety and cycling stability compared to graphite, and possess a high theoretical capacity, making them highly promising anode materials. However, the low electronic and ionic conductivity of titanium niobium oxide leads to rapid capacity decay at high currents, limiting their widespread application.

[0003] In order to obtain excellent high rate performance, the electrode requires high electronic / ionic conductivity, short charge transfer path and good contact between particles. Nanocomposite and lattice defect modification are commonly used modification strategies. Cheng Xinqun et al. from Harbin Institute of Technology conducted Nb 5+ Self-doping. Dai Sheng et al. from Oak Ridge National Laboratory in the United States synthesized nanoporous TiNb2O7 using ionic liquid as a template. George P. Demopoulos et al. from McGill University used electrophoretic deposition to realize the composite of graphene oxide and TiNb2O7. Both achieved the improvement of TNO electrochemical performance. However, the above modification strategies have limited effect on improving the lithium storage performance of TNO. Summary of the Invention

[0004] Based on the above, the present invention provides a method for preparing and applying a carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material. This method utilizes a solvent-thermally loaded metal-organic framework (MOF) precursor to induce carbon nanotube growth through heat treatment. Metal-ion-doped titanium niobium oxide is then solvothermally grown, followed by heat treatment to yield the carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material. Titanium niobium oxide nanoparticles are uniformly grown on the carbon nanotubes, resulting in excellent cycle and rate performance as a negative electrode material for lithium-ion batteries.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is a method for preparing a carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material, comprising the following steps:

[0007] placing the conductive substrate in the mixed solution A to undergo a solvothermal reaction, followed by heat treatment to obtain a carbon nanotube array containing a metal catalyst;

[0008] Immersing the carbon nanotube array containing the metal catalyst in mixed solution B to obtain a carbon nanotube array with the catalyst removed;

[0009] adding the carbon nanotube array from which the catalyst has been removed into a mixed solution C for a solvothermal reaction, followed by a heat treatment to obtain the carbon nanotube-anchored metal ion-doped titanium-niobium-oxide composite array material;

[0010] The mixed solution A includes an organic ligand and a transition metal salt;

[0011] The mixed solution B includes hydrochloric acid and ferric chloride;

[0012] The mixed solution C includes titanium salt, niobium salt and metal chloride salt.

[0013] The second technical solution of the present invention is a carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material prepared by the above-mentioned preparation method.

[0014] The third technical solution of the present invention is the application of the above-mentioned carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material in battery negative electrode materials.

[0015] A fourth technical solution of the present invention is a battery negative electrode material, the raw materials of which include the above-mentioned carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material.

[0016] The present invention discloses the following technical effects:

[0017] (1) The present invention uses vertical graphene and other substrates to load CNTs as a flexible conductive skeleton to grow TNO, obtaining a flexible composite array electrode that can be applied to flexible wearable devices. Compared with CNTs grown by ordinary CVD, the present invention uses MOFs as a precursor to promote the growth of CNTs. Because the inherent metal and organic components of MOFs can provide catalysts and carbon sources for the growth of CNTs during pyrolysis, no additional supply is required, and the organization is controllable. At the same time, MOFs-derived CNTs generally contain defects (such as N doping), which can increase the carrier concentration and thus improve the conductivity of CNTs. CNTs with a large specific surface area provide a large number of active sites for the growth of TNO, and the confined growth of TNO on its surface also prevents particle agglomeration. In addition, the CNTs array has multi-directional conductive channels and a more open electrolyte infiltration space, which can promote charge transfer more efficiently.

[0018] (2) The present invention uses a variety of modification strategies including ion doping, nanosizing, conductive composite and array integration (compounding nanostructured TNO with a conductive matrix, accelerating the electrode reaction kinetics by shortening the electron / ion transmission path inside the TNO and providing an external electron fast transmission channel; introducing impurity energy levels by doping metal ions and causing lattice distortion to accelerate the electron / ion transmission efficiency inside the TNO and improve the rate performance). The synergistic effect of various strategies helps to comprehensively improve the electrochemical lithium storage performance of TNO, showing excellent high-rate performance.

[0019] (3) The present invention utilizes solvent thermal method to carry out metal ion doping, and maintains the integrity of the array structure while successfully doping. In the past, metal ion doping of TNO was usually achieved by high-temperature solid-phase method, which is not suitable for array-loaded TNO. Because the high-temperature solid-phase method is to mix solid raw materials and sinter at high temperature to obtain TNO, it is impossible to load TNO nanoparticles onto the carbon nanotube array. The present invention utilizes solvent thermal method to realize the preparation of carbon nanotube anchored metal ion doped titanium niobium oxide composite array material. The method of the present invention greatly promotes the electrode reaction kinetics of TNO. When the carbon nanotube anchored metal ion doped titanium niobium oxide composite array material prepared by the present invention is used as an electrode material for lithium ion battery negative electrode material, it has a higher capacity and a longer cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 Scanning electron microscope (SEM) images of Ni-MOFs / VG prepared in Example 1 at different magnifications; a is a low-magnification SEM image, and b is a high-magnification SEM image.

[0022] Figure 2 These are SEM images of Co-TNO / CNTs / VG prepared in Example 1 at different magnifications; a is a low-magnification SEM image, and b is a high-magnification SEM image.

[0023] Figure 3 This is the X-ray diffraction (XRD) pattern of Co-TNO / CNTs / VG prepared in Example 1.

[0024] Figure 4 This is the battery cycle performance of Co-TNO / CNTs / VG prepared in Example 1.

[0025] Figure 5 This is the battery rate performance of Co-TNO / CNTs / VG prepared in Example 1. DETAILED DESCRIPTION

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0028] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0029] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0030] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0031] In one aspect, the present invention provides a method for preparing a carbon nanotube-anchored metal ion-doped titanium-niobium-oxide composite array material, comprising the following steps:

[0032] placing the conductive substrate in the mixed solution A to undergo a solvothermal reaction, followed by heat treatment to obtain a carbon nanotube array containing a metal catalyst;

[0033] Immersing the carbon nanotube array containing the metal catalyst in mixed solution B to obtain a carbon nanotube array with the catalyst removed;

[0034] adding the carbon nanotube array from which the catalyst has been removed into a mixed solution C for a solvothermal reaction, followed by a heat treatment (the purpose of the heat treatment is to form a TNO phase) to obtain the carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material;

[0035] The mixed solution A includes an organic ligand and a transition metal salt;

[0036] The mixed solution B includes hydrochloric acid and ferric chloride;

[0037] The mixed solution C includes titanium salt, niobium salt and metal chloride salt.

[0038] The reasons for performing the catalyst removal step in the present invention are: (1) the catalyst content is unknown, and using a metal salt with an unknown content for subsequent doping is not conducive to the experiment; (2) the catalyst is a single substance of Ni, which is not conducive to metal ion doping in solvent thermal compared to metal salts; and (3) it is easy to cause the formation of impurities.

[0039] In a preferred embodiment of the present invention, the solvent of the mixed solution A is N,N-dimethylformamide; the concentration of the organic ligand in the mixed solution A is 0.001-0.04 g / mL, and the concentration of the transition metal salt is 0.01-0.08 g / mL; the organic ligand is trimesic acid; the transition metal salt is nickel nitrate; and the conductive substrate is one of carbon cloth-loaded vertical graphene, carbon felt, carbonized cellulose film, titanium mesh, and copper foam.

[0040] The preparation method of the carbon cloth-supported vertical graphene is as follows: vertical graphene arrays are grown on carbon cloth using microwave plasma enhanced chemical vapor deposition (PECVD) technology, the carbon is arranged in a tube furnace, 30-60 sccm of methane and 40-80 sccm of hydrogen are introduced, and the reaction is carried out at a temperature of 400-700°C for 1-2 hours to obtain the carbon cloth-supported vertical graphene arrays.

[0041] In a preferred embodiment of the present invention, the conductive substrate is placed in a mixed solution A for a solvent thermal reaction, and the subsequent heat treatment step includes a solvent thermal reaction at 150-200°C for 3-5 hours, and then a heat treatment at 500-800°C for 0.5-3 hours in a hydrogen-argon mixed gas atmosphere with a hydrogen volume concentration of 5-30%.

[0042] The total flow rate of the hydrogen-argon mixed gas is 50-500 sccm.

[0043] The present invention limits the total flow rate of the hydrogen-argon mixed gas to 50-500 sccm for the following reasons: (1) too low a flow rate results in too little carbon nanotube production, hindering subsequent loading of titanium niobium oxide particles; and (2) too high a gas flow rate can blow away the substrate. Therefore, the present invention preferably limits the total flow rate of the hydrogen-argon mixed gas to 50-500 sccm.

[0044] After the step of placing the conductive substrate in the mixed solution A to carry out a solvothermal reaction, the method further includes washing and drying the obtained material before the subsequent heat treatment step.

[0045] In a preferred embodiment of the present invention, the solvent of the mixed solution B is water; the volume concentration of hydrochloric acid in the mixed solution B is 3-12%, and the concentration of ferric chloride is 0.05-0.17 g / mL; and the soaking time is 12-36 h.

[0046] After the step of immersing the carbon nanotube array containing the metal catalyst in the mixed solution B, the method further includes the steps of washing and drying.

[0047] In a preferred embodiment of the present invention, the carbon nanotube array with the catalyst removed is added to the mixed solution C for a solvothermal reaction, and the subsequent heat treatment step includes a solvothermal reaction at 180-210°C for 8-24 hours, followed by a heat treatment at 700-900°C for 1-6 hours under an inert atmosphere.

[0048] The time of the solvothermal reaction will affect the TNO particle size and loading amount, and thus affect the electrochemical performance. Therefore, the present invention preferably limits the time of the solvothermal reaction to 8-24 hours.

[0049] The reason for setting the temperature of the solvothermal reaction within the above range is that if the solvothermal temperature is too low, TNO cannot be synthesized, and if the temperature is too high, the equipment will be adversely affected.

[0050] If the heat treatment temperature is too low or the time is too short, the TNO will not form a phase, and if the heat treatment temperature is too high or the time is too long, the array structure will be destroyed. Therefore, the present invention preferably limits the heat treatment temperature to 700-900°C and the time to 1-6 hours.

[0051] The inert atmosphere is nitrogen or argon atmosphere.

[0052] After the step of adding the carbon nanotube array from which the catalyst has been removed into the mixed solution C for solvothermal reaction, the method further includes washing and drying steps before the subsequent heat treatment step.

[0053] In a preferred embodiment of the present invention, the concentration of the titanium salt in the mixed solution C is 1-3.5 mmol / L, the concentration of the niobium salt is 2.5-12 mmol / L, and the concentration of the metal chloride salt is 0.01-0.6 mmol / L; the solvent of the mixed solution is ethanol; the titanium salt is isopropyl titanate; the niobium salt is niobium pentachloride; and the metal chloride salt is at least one of cobalt chloride, manganese chloride, nickel chloride, ferric chloride, praseodymium chloride, neodymium chloride, promethium chloride, samarium chloride, europium chloride, and gadolinium chloride.

[0054] In a preferred embodiment of the present invention, the concentration of the catalyst-removing carbon nanotube arrays in the mixed solution C is 0.01-0.05 mg / mL.

[0055] If the concentration of titanium salt and niobium salt in mixed solution C is too low, TNO cannot be synthesized; if the concentration is too high, TNO loading is too high and performance is reduced; if the concentration of metal chloride salt in mixed solution C is too low, TNO doping amount is too low and cannot have beneficial effect; if the concentration is too high, impurity phase will be generated.

[0056] If the concentration of the carbon nanotube arrays in the mixed solution C is too low, the TNO loading will be too high, thereby reducing the performance. If the concentration is too high, the TNO loading will be too low, thereby reducing the battery energy density.

[0057] Another aspect of the present invention provides a carbon nanotube-anchored metal ion-doped titanium-niobium-oxide composite array material prepared by the above-mentioned preparation method.

[0058] The carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material comprises metal ion-doped titanium niobium oxide and carbon nanotubes; the metal ion-doped titanium niobium oxide particles have a size of 50-150 nm and are uniformly grown on the carbon nanotube array.

[0059] Another aspect of the present invention provides the use of the carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material in a battery negative electrode material.

[0060] Another aspect of the present invention provides a battery negative electrode material, the raw material of which includes the above-mentioned carbon nanotube-anchored metal ion-doped titanium-niobium-oxide composite array material.

[0061] The obtained carbon nanotube anchored metal ion doped titanium niobium oxide composite array material was directly cut and used as lithium ion battery electrode to assemble the battery; microporous polypropylene membrane was used as the separator, and 1 mol L -1 A coin cell battery was assembled using LiPF6 as the solute, ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio as the solvent, and a lithium sheet negative electrode. After the assembled lithium-ion battery was left for 24 hours, a constant current charge and discharge test was performed at a charge and discharge voltage of 1V-2.5V. The capacity, rate performance, and charge and discharge cycle performance of the lithium-ion battery negative electrode were tested at 25±1°C.

[0062] Unless otherwise specified, the raw materials used in the embodiments of the present invention can be obtained through commercial channels.

[0063] Example 1

[0064] In step 1, carbon was placed in a tube furnace and microwave plasma-enhanced chemical vapor deposition (PECVD) was performed (frequency 2.45 GHz, power 2 kW) with 50 sccm of methane and 70 sccm of hydrogen introduced at 600°C for 1 hour to produce carbon cloth-supported vertical graphene arrays (VG). 0.105 g of trimesic acid and 0.872 g of nickel nitrate hexahydrate were dissolved in 60 mL of N,N-dimethylformamide and stirred to produce a mixed solution A. VG was placed in mixed solution A and subjected to a solvothermal reaction at 150°C for 3 hours to grow Ni-MOFs. The mixture was then washed and dried to produce a Ni-MOFs / VG array. CNTs (carbon nanotubes) were then grown in a hydrogen-argon mixed atmosphere with a total hydrogen flow rate of 150 sccm and a volume concentration of 15% at 600°C for 2 hours to produce a carbon nanotube (CNTs / VG) array containing a metal catalyst.

[0065] Step 2, dissolve 12.5mL of hydrochloric acid and 19.5g of ferric chloride in 150mL of water and stir to obtain a mixed solution B, and soak the CNTs / VG prepared in step 1 in the mixed solution B for 24h to remove the metal catalyst, and then wash and dry. Dissolve 0.12mmol of isopropyl titanate, 0.32mmol of niobium pentachloride, and 0.009mmol of cobalt chloride in 60mL of ethanol and stir to obtain a mixed solution C. Afterwards, the CNTs / VG (containing 1mg of VG and 2mg of CNTs) from which the catalyst was removed was placed in the mixed solution C and subjected to a solvent thermal reaction at 200°C for 12h. After the reaction is completed, the material is washed and dried, and then heat-treated at 800°C in a nitrogen atmosphere for 2h to obtain a carbon nanotube-anchored cobalt-doped titanium niobium oxide composite array material, namely Co-Ti 0.82 Nb 2.12 O7 / CNTs / VG (abbreviated as Co-TNO / CNTs / VG).

[0066] Figure 1 The SEM images of Ni-MOFs / VG prepared in this example at different magnifications are shown in Figure 2. Figure 1 It can be seen that Ni-MOFs grow uniformly on the VG array.

[0067] Figure 2 The SEM images of Co-TNO / CNTs / VG prepared in this example at different magnifications are shown in Figure 2. Figure 2 It can be seen that Co-TNO presents a spherical structure of 50-100 nm.

[0068] Figure 3 The XRD pattern of Co-TNO / CNTs / VG prepared in this example is as follows: Figure 3It can be seen that the Co-TNO / CNTs / VG prepared in this example has the characteristic peaks of TiNb2O7 (JCPDS 70-2009).

[0069] Example 2

[0070] Step 1: Place the carbon in a tube furnace and use PECVD technology to introduce 50 sccm of methane and 70 sccm of hydrogen. The reaction is carried out at 600°C for 1 hour to obtain a carbon cloth-supported vertical graphene array (VG). 0.105g of trimesic acid and 0.872g of nickel nitrate hexahydrate are dissolved in 60mL of N,N-dimethylformamide and stirred to obtain a mixed solution A. VG is placed in mixed solution A and subjected to a solvothermal reaction at 150°C for 3h to grow Ni-MOFs. Afterwards, it is washed and dried to obtain a Ni-MOFs / VG array. CNTs are grown in a hydrogen-argon mixed atmosphere with a total flow rate of 150sccm and a volume concentration of 15%, and the temperature is kept at 600°C for 2h to obtain a carbon nanotube (CNTs / VG) array containing a metal catalyst.

[0071] Step 2, dissolve 12.5mL of hydrochloric acid and 19.5g of ferric chloride in 150mL of water and stir to obtain a mixed solution B, and soak the CNTs / VG prepared in step 1 in the mixed solution B for 24h to remove the metal catalyst, and then wash and dry. Dissolve 0.10mmol of isopropyl titanate, 0.34mmol of niobium pentachloride, and 0.018mmol of cobalt chloride in 60mL of ethanol and stir to obtain a mixed solution C. Afterwards, the CNTs / VG (containing 1mg of VG and 2mg of CNTs) from which the catalyst was removed was placed in the mixed solution C and subjected to a solvent thermal reaction at 200°C for 12h. After the reaction is completed, the material is washed and dried, and then heat-treated at 800°C in a nitrogen atmosphere for 2h to obtain a carbon nanotube-anchored cobalt-doped titanium niobium oxide composite array material, namely Co-Ti 0.64 Nb 2.24 O7 / CNTs / VG (abbreviated as Co-TNO / CNTs / VG).

[0072] Example 3

[0073] Step 1: Place the carbon in a tube furnace and use PECVD technology to introduce 50 sccm of methane and 70 sccm of hydrogen. The reaction is carried out at 600°C for 1 hour to obtain a carbon cloth-supported vertical graphene array (VG). 0.105g of trimesic acid and 0.872g of nickel nitrate hexahydrate are dissolved in 60mL of N,N-dimethylformamide and stirred to obtain a mixed solution A. VG is placed in mixed solution A and subjected to a solvothermal reaction at 150°C for 3h to grow Ni-MOFs. Afterwards, it is washed and dried to obtain a Ni-MOFs / VG array. CNTs are grown in a hydrogen-argon mixed atmosphere with a total flow rate of 150sccm and a volume concentration of 15%, and the temperature is kept at 600°C for 2h to obtain a carbon nanotube (CNTs / VG) array containing a metal catalyst.

[0074] Step 2, dissolve 12.5mL of hydrochloric acid and 19.5g of ferric chloride in 150mL of water and stir to obtain a mixed solution B, and soak the CNTs / VG prepared in step 1 in the mixed solution B for 24h to remove the metal catalyst, and then wash and dry. Dissolve 0.15mmol of isopropyl titanate, 0.30mmol of niobium pentachloride, and 0.0015mmol of cobalt chloride in 60mL of ethanol and stir to obtain a mixed solution C. After that, the CNTs / VG (containing 1mg of VG and 2mg of CNTs) from which the catalyst was removed was placed in the mixed solution C and subjected to a solvent thermal reaction at 200°C for 12h. After the reaction is completed, the material is washed and dried, and then heat-treated at 800°C in a nitrogen atmosphere for 2h to obtain a carbon nanotube-anchored cobalt-doped titanium niobium oxide composite array material, namely Co-Ti 0.97 Nb 2.02 O7 / CNTs / VG (abbreviated as Co-TNO / CNTs / VG).

[0075] Example 4

[0076] Step 1: Place the carbon in a tube furnace and use PECVD technology to introduce 50 sccm of methane and 70 sccm of hydrogen. The reaction is carried out at 600°C for 1 hour to obtain a carbon cloth-supported vertical graphene array (VG). 0.105g of trimesic acid and 0.872g of nickel nitrate hexahydrate are dissolved in 60mL of N,N-dimethylformamide and stirred to obtain a mixed solution A. VG is placed in mixed solution A and subjected to a solvothermal reaction at 150°C for 3h to grow Ni-MOFs. Afterwards, it is washed and dried to obtain a Ni-MOFs / VG array. CNTs are grown in a hydrogen-argon mixed atmosphere with a total flow rate of 150sccm and a volume concentration of 15%, and the temperature is kept at 600°C for 2h to obtain a carbon nanotube (CNTs / VG) array containing a metal catalyst.

[0077] Step 2, dissolve 12.5mL of hydrochloric acid and 19.5g of ferric chloride in 150mL of water and stir to obtain a mixed solution B, and soak the CNTs / VG prepared in step 1 in the mixed solution B for 24h to remove the metal catalyst, and then wash and dry. Dissolve 0.12mmol of isopropyl titanate, 0.32mmol of niobium pentachloride, and 0.009mmol of cobalt chloride in 60mL of ethanol and stir to obtain a mixed solution C. Afterwards, the CNTs / VG (containing 1mg of VG and 2mg of CNTs) from which the catalyst was removed was placed in the mixed solution C and subjected to a solvent thermal reaction at 200°C for 8h. After the reaction is completed, the material is washed and dried, and then heat-treated at 800°C in a nitrogen atmosphere for 2h to obtain a carbon nanotube-anchored cobalt-doped titanium niobium oxide composite array material, namely Co-Ti 0.82 Nb 2.12 O7 / CNTs / VG (abbreviated as Co-TNO / CNTs / VG).

[0078] Example 5

[0079] Step 1: Place the carbon in a tube furnace and use PECVD technology to introduce 50 sccm of methane and 70 sccm of hydrogen. The reaction is carried out at 600°C for 1 hour to obtain a carbon cloth-supported vertical graphene array (VG). 0.105g of trimesic acid and 0.872g of nickel nitrate hexahydrate are dissolved in 60mL of N,N-dimethylformamide and stirred to obtain a mixed solution A. VG is placed in mixed solution A and subjected to a solvothermal reaction at 150°C for 3h to grow Ni-MOFs. Afterwards, it is washed and dried to obtain a Ni-MOFs / VG array. CNTs are grown in a hydrogen-argon mixed atmosphere with a total flow rate of 150sccm and a hydrogen concentration of 15%, and the temperature is kept at 600°C for 2h to obtain a carbon nanotube (CNTs / VG) array containing a metal catalyst.

[0080] Step 2, dissolve 12.5mL of hydrochloric acid and 19.5g of ferric chloride in 150mL of water and stir to obtain a mixed solution B, and soak the CNTs / VG prepared in step 1 in the mixed solution B for 24h to remove the metal catalyst, and then wash and dry. Dissolve 0.12mmol of isopropyl titanate, 0.32mmol of niobium pentachloride, and 0.009mmol of cobalt chloride in 60mL of ethanol and stir to obtain a mixed solution C. After that, the CNTs / VG (containing 1mg of VG and 2mg of CNTs) from which the catalyst was removed was placed in the mixed solution C and subjected to a solvent thermal reaction at 200°C for 24h. After the reaction is completed, the material is washed and dried, and then heat-treated at 800°C in a nitrogen atmosphere for 2h to obtain a carbon nanotube-anchored cobalt-doped titanium niobium oxide composite array material, namely Co-Ti 0.82 Nb 2.12O7 / CNTs / VG (abbreviated as Co-TNO / CNTs / VG).

[0081] Example 6

[0082] Step 1: Place the carbon in a tube furnace and use PECVD technology to introduce 50 sccm of methane and 70 sccm of hydrogen. The reaction is carried out at 600°C for 1 hour to obtain a carbon cloth-supported vertical graphene array (VG). 0.105g of trimesic acid and 0.872g of nickel nitrate hexahydrate are dissolved in 60mL of N,N-dimethylformamide and stirred to obtain a mixed solution A. VG is placed in mixed solution A and subjected to a solvothermal reaction at 150°C for 3h to grow Ni-MOFs. Afterwards, it is washed and dried to obtain a Ni-MOFs / VG array. CNTs are grown in a hydrogen-argon mixed atmosphere with a total flow rate of 150sccm and a volume concentration of 15%, and the temperature is kept at 600°C for 2h to obtain a carbon nanotube (CNTs / VG) array containing a metal catalyst.

[0083] Step 2, dissolve 12.5mL of hydrochloric acid and 19.5g of ferric chloride in 150mL of water and stir to obtain a mixed solution B, and soak the CNTs / VG prepared in step 1 in the mixed solution B for 24h to remove the metal catalyst, and then wash and dry. Dissolve 0.12mmol of isopropyl titanate, 0.32mmol of niobium pentachloride, and 0.009mmol of manganese chloride in 60mL of ethanol and stir to obtain a mixed solution C. After that, the CNTs / VG (containing 1mg of VG and 2mg of CNTs) with the catalyst removed is placed in the mixed solution C and subjected to a solvent thermal reaction at 200°C for 12h. After the reaction is completed, the material is washed and dried, and then heat-treated at 800°C in a nitrogen atmosphere for 2h to obtain a carbon nanotube-anchored manganese-doped titanium niobium oxide composite array material, namely Mn-Ti 0.82 Nb 2.12 O7 / CNTs / VG (abbreviated as Mn-TNO / CNTs / VG).

[0084] The carbon nanotube anchored metal ion doped titanium niobium oxide composite array materials (Co-TNO / CNTs / VG, Mn-TNO / CNTs / VG) prepared in Examples 1-6 were cut into 1 cm 2 The size of the battery was directly used as the lithium-ion battery electrode assembly battery. Microporous polypropylene membrane was used as the separator, and 1 mol L -1 A coin cell battery was assembled using LiPF6 as the solute, an electrolyte consisting of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio as the solvent, and a lithium anode sheet. Constant current charge and discharge tests were performed on the assembled lithium-ion battery, setting the charge and discharge voltage range to 2.5V-1V.

[0085] With the change of doping amount, solvothermal time and doping ion, the lithium-ion battery exhibits different electrochemical properties. The maximum discharge capacity of the lithium-ion battery at different current densities after the carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array materials in Examples 1-6 are assembled as lithium-ion electrode materials is shown in Table 1:

[0086] Table 1

[0087]

[0088] As can be seen from Table 1, changing the amount of doping source will change the TNO doping amount, thereby affecting its crystal structure and further affecting the electrochemical performance; the solvent thermal time will affect the TNO particle size and loading amount, thereby affecting the electrochemical performance.

[0089] Figure 4 The battery cycle performance of Co-TNO / CNTs / VG prepared in Example 1 (test method is the same as above). Figure 4 It can be seen that the lithium-ion battery exhibits excellent electrochemical performance at a current density of 10C. At a current density of 10C, after 500 cycles, it can maintain 209mAh g -1 The specific capacity (capacity retention rate is 86.7%).

[0090] Figure 5 The battery rate performance of Co-TNO / CNTs / VG prepared in Example 1 (test method is the same as above). Figure 5 As can be seen, at a current density of 1C there is 339mAh g -1 The high specific capacity is 103 mAh g at a current density of 30C. -1 The capacity shows the excellent high rate performance of the material.

[0091] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material, characterized in that: The following steps are involved: The conductive substrate is placed in the mixed solution A for a solvothermal reaction, and then heat-treated at 500-800°C for 0.5-3 h in a hydrogen-argon mixed atmosphere with a hydrogen volume concentration of 5-30% to obtain a carbon nanotube array containing a metal catalyst; Immersing the carbon nanotube array containing the metal catalyst in mixed solution B to obtain a carbon nanotube array with the catalyst removed; Adding the carbon nanotube array from which the catalyst has been removed to the mixed solution C for solvothermal reaction at 180-210° C. for 8-24 h, followed by heat treatment at 700-900° C. for 1-6 h under an inert atmosphere to obtain the carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material; The mixed solution A includes an organic ligand and a transition metal salt, wherein the organic ligand is trimesic acid and the transition metal salt is nickel nitrate; The mixed solution B includes hydrochloric acid and ferric chloride; The mixed solution C includes titanium salt, niobium salt and metal chloride; the concentration of titanium salt in the mixed solution C is 1-3.5 mmol / L, the concentration of niobium salt is 2.5-12 mmol / L, and the concentration of metal chloride is 0.01-0.6 mmol / L; the concentration of the carbon nanotube array from which the catalyst is removed in the mixed solution C is 0.01-0.05 mg / mL; The total flow rate of the hydrogen-argon mixed gas is 50-500 sccm.

2. The preparation method according to claim 1, characterized in that The solvent of the mixed solution A is N,N-dimethylformamide; the concentration of the organic ligand in the mixed solution A is 0.001-0.04 g / mL, and the concentration of the transition metal salt is 0.01-0.08 g / mL; the conductive substrate is one of carbon cloth-loaded vertical graphene, carbon felt, carbonized cellulose film, titanium mesh and foam copper.

3. The preparation method according to claim 1, characterized in that The step of placing the conductive substrate in the mixed solution A for a solvothermal reaction comprises a solvothermal reaction at 150-200° C. for 3-5 hours.

4. The preparation method according to claim 1, characterized in that The solvent of the mixed solution B is water; the volume concentration of hydrochloric acid in the mixed solution B is 3-12%, and the concentration of ferric chloride is 0.05-0.17 g / mL; and the soaking time is 12-36 h.

5. The preparation method according to claim 1, characterized in that The solvent of the mixed solution C is ethanol; the titanium salt is isopropyl titanate; the niobium salt is niobium pentachloride; and the metal chloride salt is at least one of cobalt chloride, manganese chloride, nickel chloride, ferric chloride, praseodymium chloride, neodymium chloride, promethium chloride, samarium chloride, europium chloride, and gadolinium chloride. 6 . The carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material prepared by the preparation method according to claim 1 .

7. Use of the carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material as claimed in claim 6 in anode materials for batteries.

8. A battery negative electrode material, characterized in that: The raw materials include the carbon nanotube-anchored metal ion-doped titanium niobium oxide composite array material according to claim 6.

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