VN / tio composite three-dimensional self-supporting electrode material for aqueous zinc ion battery and preparation method and application thereof

Abstract

The application provides a VN / TiO composite three-dimensional self-supporting electrode material for a water-based zinc ion battery and a preparation method and application thereof, and belongs to the technical field of battery materials.The VN / TiO composite three-dimensional self-supporting electrode material is obtained by growing TiO2 nanorods on a substrate, then loading vanadium oxide precursors on the TiO2 nanorods, and finally performing annealing treatment under an NH3 atmosphere.The electrode material has a hollow nanotube structure, and VN microcrystals grow in the form of nanospheres on the hollow nanotubes, so that the structure can increase the contact area of the active material and the electrolyte, is conducive to ion transmission, shortens the diffusion path of ions, and can effectively improve the electrochemical performance of the material.The preparation method provided by the application is simple, low in cost, suitable for industrial large-scale production, and can be widely applied in the field of water-based zinc ion batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery materials, in particular to a VN / TiO composite three-dimensional self-supporting electrode material for aqueous zinc ion batteries and a preparation method and application thereof. BACKGROUND

[0002] With the vigorous support of the state for new energy, compared with the current lithium ion battery, the aqueous zinc ion battery as a green and environmentally friendly new energy has the advantages of high energy density, high safety, cheap electrolyte, easy recovery, etc., and the reserves of zinc are very rich, the current estimated reserves of zinc are more than 1.9 billion tons, which is 20 times of the 89 million tons of lithium ore exploration, and the aqueous zinc ion battery preparation requires a lower environment, and does not require a waterless and oxygen-free environment, so it has been widely concerned by researchers at present.

[0003] Similar to lithium ion batteries, the energy density and power density of aqueous zinc ion batteries mainly depend on the positive electrode material, which bears the role of zinc ion insertion into the host. When the hydrated zinc ion is inserted into the lattice of the positive electrode material, it first loses the bound water and then moves to a lower energy thermodynamic stable position, so the performance of the aqueous zinc ion battery is mainly related to the interaction between the positive electrode material lattice and Zn 2+ , specifically the adsorption strength of Zn 2+ in the positive electrode material, the strong electrostatic interaction with the lattice, the electron exchange speed with the lattice, the migration speed in the host lattice, and the electronic transmission speed of the lattice body. In addition, the stability of the aqueous zinc ion positive electrode material also depends on the crystal structure, physical and chemical properties, and the process of inserting Zn 2+ and the product. However, the current aqueous zinc ion battery still has the problems of low voltage, low energy density, slow positive electrode kinetic reaction, unclear zinc storage mechanism, etc.

[0004] Therefore, it is of great importance to the practical application to reasonably design the composition and structure of the aqueous zinc ion battery positive electrode material, so as to improve its electrochemical activity and stability as an electrode material in the zinc ion battery. SUMMARY

[0005] Therefore, the present application aims to provide a VN / TiO composite three-dimensional self-supporting electrode material for aqueous zinc ion batteries, a preparation method and application thereof. The VN / TiO composite three-dimensional self-supporting electrode material for aqueous zinc ion batteries provided by the present application can effectively improve the electrochemical performance of the material.

[0006] In order to achieve the above object, the present application provides the following technical scheme: a preparation method of a VN / TiO composite three-dimensional self-supporting electrode material for aqueous zinc ion batteries, first growing TiO2 nanorods on a substrate, then loading vanadium oxide precursors on the TiO2 nanorods, and finally performing annealing treatment in an NH3 atmosphere to obtain the VN / TiO composite three-dimensional self-supporting electrode material.

[0007] Preferably, the preparation method comprises the following steps:

[0008] (1) The substrate is pretreated and then soaked in a mixed solution of deionized water and a Ti-containing compound, dried, and the soaking and drying steps are repeated to obtain a substrate with TiO2 seeds grown thereon;

[0009] (2) The Ti-containing compound is dissolved in hydrochloric acid, and the substrate with TiO2 seeds grown thereon obtained in step (1) is placed in the acid solution containing the Ti-containing compound to perform a hydrothermal reaction, and after the reaction is completed, annealing treatment is performed to obtain a substrate with TiO2 nanorods grown thereon;

[0010] (3) Ammonium metavanadate, ammonia water and deionized water are stirred until all the powders are dissolved, then thioacetamide is added and stirred until the mixed solution is a transparent liquid, and the substrate with TiO2 nanorods grown thereon in step (2) is subjected to a hydrothermal reaction with the above mixed solution to obtain a substrate containing vanadium oxide precursors;

[0011] (4) The substrate containing vanadium oxide precursors obtained in step (3) is annealed in an NH3 atmosphere, and after natural cooling to room temperature, the VN / TiO composite three-dimensional self-supporting electrode material is obtained.

[0012] Further preferably, the Ti-containing compound is at least one of titanium tetrachloride, hexafluorotitanic acid, tetrabutyl titanate, isopropyl titanate and tetraethyl titanate.

[0013] Further preferably, the drying temperature in step (1) is 300-400℃.

[0014] Further preferably, the volume ratio of deionized water to Ti-containing compound in step (1) is (40-50):1.

[0015] Further preferably, the hydrothermal reaction temperature in step (2) is 140-180℃, and the hydrothermal reaction time is 3-6h; the annealing treatment temperature is 400-700℃, and the annealing treatment time is 0.5-2h.

[0016] Further preferably, the hydrothermal reaction temperature in step (3) is 160-180℃, and the hydrothermal reaction time is 3-6h.

[0017] Further preferably, the annealing temperature in step (4) is 600-800 DEG C, the annealing time is 1-3 h, and the heating rate is 5-10 DEG C / min.

[0018] The application further provides the VN / TiO composite three-dimensional self-supporting electrode material prepared by the preparation method.

[0019] The application further provides application of the VN / TiO composite three-dimensional self-supporting electrode material as a positive electrode material of a zinc ion battery.

[0020] Beneficial technical effects:

[0021] 1. The VN / TiO composite three-dimensional self-supporting electrode material prepared by the application has no conductive agent and no binder in the electrode structure, so that the energy density of the battery is increased, the binding force between the active material and the current collector is stronger and more uniform, there is no dead volume, the utilization efficiency of the active material is further improved, and the electron mobility is higher.

[0022] 2. The TiO hollow nanotube of the VN / TiO composite three-dimensional self-supporting electrode material prepared by the application can well buffer the volume change and electrochemical impact during Zn 2+ insertion and extraction, and the VN microcrystal loaded on the hollow nanotube can increase the contact area of the active material and the electrolyte, which is beneficial to ion transmission and shortens the diffusion path of ions.

[0023] 3. The preparation method of the VN / TiO composite three-dimensional self-supporting electrode material is simple, has high preparation efficiency and low cost, and can be used for large-scale production.

[0024] 4. The material prepared by the application has raw materials that are easy to obtain, a simple preparation process, and is suitable for industrialized production, and has a wide application prospect in the field of water-based zinc ion battery electrodes. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 X-ray diffraction patterns of the VN / TiO composite three-dimensional self-supporting electrode material obtained in Example 2 and the VN self-supporting electrode material obtained in Comparative Example 1 and the carbon cloth substrate;

[0026] Figure 2 A scanning electron microscope image of the VN self-supporting electrode material obtained in Comparative Example 1;

[0027] Figure 3 A scanning electron microscope image of the VN / TiO composite three-dimensional self-supporting electrode material obtained in Example 2;

[0028] Figure 4The rate performance curves of the VN / TiO composite three-dimensional self-supporting electrode material obtained in Example 2 and the VN self-supporting electrode material obtained in Comparative Example 1 as the positive electrode material of the aqueous zinc ion battery are compared;

[0029] Figure 5 The first charge-discharge curves of the VN / TiO composite three-dimensional self-supporting electrode material obtained in Example 2 and the VN self-supporting electrode material obtained in Comparative Example 1 as the positive electrode material of the aqueous zinc ion battery;

[0030] Figure 6 The specific capacity graph of the VN / TiO composite three-dimensional self-supporting electrode material obtained in Example 2 and the VN self-supporting electrode material obtained in Comparative Example 1 as the positive electrode material of the aqueous zinc ion battery under a current density of 2 A / g after 1000 cycles. DETAILED DESCRIPTION

[0031] The application provides a preparation method of a VN / TiO composite three-dimensional self-supporting electrode material for an aqueous zinc ion battery.

[0032] In the application, the preparation method specifically comprises the following steps:

[0033] (1) The substrate is pretreated, then immersed in a mixed solution of deionized water and a Ti-containing compound, and dried, and the immersion and drying steps are repeated to obtain a substrate with TiO2 seeds grown thereon.

[0034] In the application, the substrate is preferably carbon cloth; the pretreatment is to cut the substrate and then immerse it in concentrated nitric acid, and then ultrasonically clean it with deionized water and ethanol respectively, the concentration of the concentrated nitric acid is ≤68%, and the concentration of the ethanol is ≥95%; the Ti-containing compound is preferably at least one of titanium tetrachloride, hexafluorotitanic acid, tetrabutyl titanate, isopropyl titanate and tetraethyl titanate, and more preferably titanium tetrachloride; the volume ratio of the deionized water to the Ti-containing compound is preferably (40-50):1; and the drying temperature is preferably 300-400℃.

[0035] (2) The Ti-containing compound is dissolved in hydrochloric acid, and the substrate with TiO2 seeds grown thereon obtained in step (1) is put into the acid solution containing the Ti-containing compound for hydrothermal reaction, and then annealed after the reaction is completed to obtain a substrate with TiO2 nanorods grown thereon.

[0036] In the present application, the hydrochloric acid is obtained by mixing deionized water and concentrated hydrochloric acid at a volume ratio of 1:1; the hydrothermal reaction temperature is 140-180 DEG C, and the hydrothermal reaction time is 3-6h; the annealing temperature is 400-700 DEG C, and the annealing time is 0.5-2h.

[0037] (3) stirring ammonium metavanadate, ammonia and deionized water until all powders are dissolved, then adding thioacetamide and stirring until the mixed solution is a transparent liquid, and subjecting the substrate with TiO2 nanorods grown in the step (2) to hydrothermal reaction with the mixed solution to obtain a substrate containing a vanadium oxide precursor.

[0038] In the present application, the adding amount of the ammonium metavanadate, ammonia and thioacetamide is controlled to be 1mmol of ammonium metavanadate, 2ml of ammonia and 7mmol of thioacetamide per 30ml of deionized water; the hydrothermal reaction temperature is preferably 160-180 DEG C, and the hydrothermal reaction time is preferably 3-6h.

[0039] (4) annealing the substrate containing the vanadium oxide precursor obtained in the step (3) in an NH3 atmosphere, and naturally cooling to room temperature to obtain the VN / TiO composite three-dimensional self-supporting electrode material.

[0040] In the present application, the annealing temperature is preferably 600-800 DEG C, the annealing time is preferably 1-3h, and the heating rate is preferably 5-10 DEG C / min.

[0041] The present application also provides a VN / TiO composite three-dimensional self-supporting electrode material for aqueous zinc ion batteries prepared by the preparation method.

[0042] The present application also provides an application of the VN / TiO composite three-dimensional self-supporting electrode material as a positive electrode material for aqueous zinc ion batteries.

[0043] In order to better understand the present application, the content of the present application is further illustrated by the following examples, but the content of the present application is not limited to the following examples.

[0044] Example 1

[0045] (1) cutting carbon cloth into pieces, then immersing in concentrated nitric acid, and taking out and ultrasonically cleaning in deionized water and ethanol for 3 times; adding 20ml of deionized water and 0.4ml of titanium tetrachloride into a beaker to mix and stir to form a titanium-containing mixed solution, immersing the cleaned carbon cloth into the titanium-containing mixed solution, then taking out and baking on a 300 DEG C hot plate, and after baking and drying, immersing again into the titanium-containing mixed solution, and repeating the above steps for 5 times to obtain carbon cloth with TiO2 seeds grown thereon;

[0046] (2) Put the deionized water and concentrated hydrochloric acid with a volume ratio of 1:1 into a beaker and stir until uniform, then add 0.6 ml of tetrabutyl titanate and mix, and then transfer to a 50 ml reaction kettle. Put the carbon cloth seeded with TiO2 obtained in step (1) into the reaction kettle, and perform hydrothermal reaction at 140°C for 6h. After hydrothermal reaction, wash with deionized water and ethanol three times, and then place in a muffle furnace and anneal at 400°C for 1h to obtain carbon cloth substrate seeded with TiO2 nanorods;

[0047] (3) Mix 1 mmol of ammonium metavanadate, 2 ml of ammonia water and 30 ml of deionized water in a beaker until the powder is completely dissolved, then add 7 mmol of thioacetamide and stir until the mixed solution is a transparent liquid. Put the carbon cloth seeded with TiO2 nanorods in step (2) and the above mixed solution into a 25 ml reaction kettle, and perform hydrothermal reaction at 160°C for 3h to obtain carbon cloth containing vanadium oxide precursor;

[0048] (4) Continue to anneal the carbon cloth containing vanadium oxide precursor obtained in step (3) at 600°C for 1h in an NH3 atmosphere, with a heating rate of 5°C / min. After natural cooling to room temperature, the VN / TiO composite three-dimensional self-supporting electrode material is obtained.

[0049] Example 2

[0050] (1) Cut the carbon cloth into pieces, then immerse in concentrated nitric acid, and then wash in deionized water and ethanol three times each. Add 20 ml of deionized water and 0.4 ml of titanium tetrachloride to a beaker and mix to form a titanium-containing mixed solution. Immerse the washed carbon cloth in the titanium-containing mixed solution, then take it out and bake on a 300°C hot plate. After baking, immerse it again in the titanium-containing mixed solution. Repeat the above steps 5 times to obtain carbon cloth seeded with TiO2;

[0051] (2) Put the deionized water and concentrated hydrochloric acid with a volume ratio of 1:1 into a beaker and stir until uniform, then add 0.6 ml of tetrabutyl titanate and mix, and then transfer to a 50 ml reaction kettle. Put the carbon cloth seeded with TiO2 obtained in step (1) into the reaction kettle, and perform hydrothermal reaction at 160°C for 5h. After hydrothermal reaction, wash with deionized water and ethanol three times, and then place in a muffle furnace and anneal at 550°C for 1h to obtain carbon cloth substrate seeded with TiO2 nanorods;

[0052] (3) 1 mmol of ammonium metavanadate, 2 ml of ammonia water and 30 ml of deionized water were mixed and stirred in a beaker until the powders were completely dissolved, 7 mmol of thioacetamide was then added and stirred until the mixed solution became a transparent liquid, the carbon cloth substrate with TiO2 nanorods grown in step (2) was placed in a 25 ml reaction kettle with the above mixed solution, and hydrothermal reaction was carried out at 160°C for 6 h to obtain a carbon cloth containing vanadium oxide precursor;

[0053] (4) The carbon cloth containing vanadium oxide precursor obtained in step (3) was further annealed in an NH3 atmosphere at 700°C for 2.5 h at a heating rate of 5°C / min, and the VN / TiO composite three-dimensional self-supporting electrode material was obtained after natural cooling to room temperature.

[0054] Example 3

[0055] (1) The carbon cloth was cut into pieces and then immersed in concentrated nitric acid, and after being taken out, it was ultrasonically cleaned in deionized water and ethanol for 3 times respectively; 20 ml of deionized water and 0.4 ml of titanium tetrachloride were added into a beaker and mixed and stirred to form a titanium-containing mixed solution, and the cleaned carbon cloth was placed in the above titanium-containing mixed solution for immersion, and then taken out and baked on a 400°C hot plate, after drying, it was placed in the above Ti-containing mixed solution for immersion again, and the above steps were repeated for 5 times to obtain carbon cloth with TiO2 seeds grown;

[0056] (2) Deionized water and concentrated hydrochloric acid with a volume ratio of 1:1 were placed in a beaker and stirred uniformly, then 0.6 ml of tetrabutyl titanate was added and mixed and stirred, and transferred to a 50 ml reaction kettle, the carbon cloth with TiO2 seeds grown obtained in step (1) was placed in the reaction kettle, and hydrothermal reaction was carried out at 150°C for 4 h, and after hydrothermal reaction, it was washed with deionized water and ethanol for 3 times, and then dried and placed in a muffle furnace for annealing at 500°C for 1.5 h to obtain a carbon cloth substrate with TiO2 nanorods grown;

[0057] (3) 1 mmol of ammonium metavanadate, 2 ml of ammonia water and 30 ml of deionized water were mixed and stirred in a beaker until the powders were completely dissolved, 7 mmol of thioacetamide was then added and stirred until the mixed solution became a transparent liquid, the carbon cloth substrate with TiO2 nanorods grown in step (2) was placed in a 25 ml reaction kettle with the above mixed solution, and hydrothermal reaction was carried out at 160°C for 4 h to obtain a carbon cloth containing vanadium oxide precursor;

[0058] (4) The carbon cloth containing vanadium oxide precursor obtained in step (3) was further annealed in an NH3 atmosphere at 600°C for 2 h at a heating rate of 5°C / min, and the VN / TiO composite three-dimensional self-supporting electrode material was obtained after natural cooling to room temperature.

[0059] Example 4

[0060] (1) The carbon cloth was cut into pieces and then immersed in concentrated nitric acid. After being taken out, it was ultrasonically cleaned in deionized water and ethanol for 3 times, respectively. 20 ml of deionized water and 0.4 ml of titanium tetrachloride were added into a beaker and mixed to form a titanium-containing mixed solution. The cleaned carbon cloth was immersed in the titanium-containing mixed solution, and then taken out and baked on a 350°C hot plate. After drying, it was continuously immersed in the Ti-containing mixed solution. The above steps were repeated 5 times to obtain carbon cloth with TiO2 seeds grown thereon;

[0061] (2) Deionized water and concentrated hydrochloric acid with a volume ratio of 1:1 were added into a beaker and stirred uniformly. Then 0.6 ml of tetrabutyl titanate was added and mixed, and transferred to a 50 ml reaction kettle. The carbon cloth with TiO2 seeds grown thereon obtained in step (1) was placed in the reaction kettle and subjected to hydrothermal reaction at 170°C for 4 h. After hydrothermal reaction, it was washed with deionized water and ethanol for 3 times, and then dried. It was then placed in a muffle furnace and annealed at 600°C for 1 h to obtain carbon cloth substrate with TiO2 nanorods grown thereon;

[0062] (3) 1 mmol of ammonium metavanadate, 2 ml of ammonia water and 30 ml of deionized water were mixed and stirred in a beaker until the powder was completely dissolved. Then 7 mmol of thioacetamide was added and stirred to dissolve until the mixed solution became a transparent liquid. The carbon cloth substrate with TiO2 nanorods grown thereon in step (2) was placed in a 25 ml reaction kettle together with the above mixed solution, and subjected to hydrothermal reaction at 170°C for 2 h to obtain carbon cloth containing vanadium oxide precursor;

[0063] (4) The carbon cloth containing vanadium oxide precursor obtained in step (3) was annealed in NH3 atmosphere at 700°C for 1.5 h with a heating rate of 5°C / min. After natural cooling to room temperature, the VN / TiO2 composite three-dimensional self-supporting electrode material was obtained.

[0064] Example 5

[0065] (1) The carbon cloth was cut into pieces and then immersed in concentrated nitric acid. After being taken out, it was ultrasonically cleaned in deionized water and ethanol for 3 times, respectively. 20 ml of deionized water and 0.4 ml of titanium tetrachloride were added into a beaker and mixed to form a titanium-containing mixed solution. The cleaned carbon cloth was immersed in the titanium-containing mixed solution, and then taken out and baked on a 300°C hot plate. After drying, it was continuously immersed in the Ti-containing mixed solution. The above steps were repeated 5 times to obtain carbon cloth with TiO2 seeds grown thereon;

[0066] (2) Put deionized water and concentrated hydrochloric acid with a volume ratio of 1:1 into a beaker and stir until uniform, then add tetrabutyl titanate and mix, and then transfer to a 50 ml reaction kettle, and put the carbon cloth seeded with TiO2 obtained in step (1) into the reaction kettle, and perform hydrothermal reaction at 180°C for 3h, and then wash with deionized water and ethanol three times, and then dry and place in a muffle furnace at 700°C for 0.5h to obtain carbon cloth substrate seeded with TiO2 nanorods;

[0067] (3) Mix 1 mmol of ammonium metavanadate, 2 ml of ammonia water and 30 ml of deionized water in a beaker and stir until the powder is completely dissolved, then add 7 mmol of thioacetamide and stir until the mixed solution is a transparent liquid, then put the carbon cloth substrate seeded with TiO2 nanorods in step (2) and the above mixed solution into a 25 ml reaction kettle, and perform hydrothermal reaction at 180°C for 1h to obtain carbon cloth containing vanadium oxide precursor;

[0068] (5) Continue to anneal the carbon cloth containing vanadium oxide precursor obtained in step (4) in an NH3 atmosphere at 800°C for 1h at a heating rate of 5°C / min, and then cool naturally to room temperature to obtain the VN / TiO composite three-dimensional self-supporting electrode material.

[0069] Comparative Example 1

[0070] This comparative example is to directly grow VN self-supporting electrode material on carbon cloth

[0071] The preparation method is as follows:

[0072] (1) Cut the carbon cloth into pieces, then immerse in concentrated nitric acid, and then wash in deionized water and ethanol three times;

[0073] (2) Mix 1 mmol of ammonium metavanadate, 2 ml of ammonia water and 30 ml of deionized water in a beaker and stir until the powder is completely dissolved, then add 7 mmol of thioacetamide and stir until the mixed solution is a transparent liquid, then put the cleaned carbon cloth substrate in step (1) and the above mixed solution into a 25 ml reaction kettle, and perform hydrothermal reaction at 180°C for 6h to obtain carbon cloth containing vanadium oxide precursor;

[0074] (3) Continue to anneal the carbon cloth containing vanadium oxide precursor obtained in step (2) in an NH3 atmosphere at 700°C for 2.5h at a heating rate of 5°C / min, and then cool naturally to room temperature to obtain the VN self-supporting electrode material.

[0075] The VN / TiO composite three-dimensional self-supporting electrode material obtained in Comparative Example 2 and the VN self-supporting electrode material obtained in Comparative Example 1 and the carbon cloth substrate were characterized by XRD, and the results are shown in Figure 2.Figure 1 It can be seen that the XRD diffraction patterns of the samples of Example 2 and Comparative Example 1 both correspond to the VN (PDF#89-5267) standard card, indicating that VN products are generated. In addition, the XRD diffraction pattern of Example 2 also corresponds to the TiO (PDF#89-3660) standard card, which is because the TiO2 grown on the carbon cloth substrate is reduced by NH3 high-temperature annealing, thereby generating TiO products.

[0076] The electrode materials obtained in Comparative Example 1 and Example 2 were characterized by scanning electron microscopy, and it can be seen that Figure 2 and Figure 3 It can be seen that the VN of the VN self-supporting electrode material of Comparative Example 1 grows on the carbon cloth, and part of the nanosheets formed are agglomerated to form a dense block structure, which is not conducive to the contact of the electrolyte and reduces the active sites; the VN nanosheets of the VN / TiO composite three-dimensional self-supporting electrode material of Example 2 grow on the hollow nanotubes of TiO, and the nanosheets are uniformly dispersed and thinner, and this composite structure can more effectively allow the electrolyte to be soaked and be conducive to providing diffusion channels for the diffusion of Zn 2+ ions.

[0077] Test experiment:

[0078] The VN / TiO composite three-dimensional self-supporting electrode material prepared in Example 2 and the VN self-supporting electrode material prepared in Comparative Example 1 were respectively used as the positive electrode to prepare aqueous zinc ion batteries and perform electrochemical performance analysis: the self-supporting electrode material was cut into a piece with a diameter of 1x1 cm, a metal zinc sheet was used as the negative electrode in an air atmosphere, a GFD separator was used, the electrolyte was a 2 mol / L ZnSO4 solution, and the batteries were assembled in the order of negative electrode shell-zinc sheet-separator-positive electrode-gasket-spring piece-positive electrode shell, and sealed with a manual hydraulic sealing machine under a pressure of 50Mpa, to form a CR2032 type button cell. The electrochemical performance was tested by a new battery tester.

[0079] The rate performance of the prepared aqueous zinc ion batteries was tested, and it can be seen that Figure 4 The VN / TiO composite three-dimensional self-supporting electrode material prepared in Example 2 has the best rate performance, indicating that it has better charge transfer and zinc ion diffusion rate.

[0080] The prepared aqueous zinc ion batteries were subjected to the first charge and discharge at a current density of 1A / g between 0.2-1.8V. It can be seen that Figure 5 The first discharge specific capacity of the battery prepared by the electrode material of Example 2 is higher than that of Comparative Example 1, indicating that the hollow nanotubes formed increase the contact area of the active material and the electrolyte, increase the diffusion path of the zinc ions, and thereby improve the electrochemical performance.

[0081] At 25°C, 1000 charge-discharge cycles were performed at 2A / g between 0.2-1.8V, and the capacity retention rate was calculated. Figure 6 It can be seen that the VN / TiO composite three-dimensional self-supporting electrode material obtained in Example 2 still has a performance retention rate of 71% after 1000 cycles, while the performance retention rate of the VN self-supporting electrode material obtained in Comparative Example 1 is only 27%, indicating excellent electrochemical stability.

[0082] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A method for preparing a VN / TiO composite three-dimensional self-supporting electrode material for aqueous zinc ion batteries, characterized in that, The VN / TiO composite three-dimensional self-supporting electrode material is obtained by growing TiO2 nanorods on a substrate, loading vanadium oxide precursor on the TiO2 nanorods, and then performing annealing treatment in an NH3 atmosphere; wherein the structure of the TiO is a hollow nanotube. The preparation method comprises the following steps: (1) pretreating the substrate, then immersing the substrate in a mixed solution of deionized water and a Ti-containing compound, drying, repeating the immersion and drying steps, and obtaining a substrate with TiO2 seeds; (2) dissolving the Ti-containing compound in hydrochloric acid, immersing the substrate with TiO2 seeds obtained in step (1) in the acid solution containing the Ti-containing compound to perform hydrothermal reaction, and then performing annealing treatment after the reaction to obtain a substrate with TiO2 nanorods; (3) stirring ammonium metavanadate, ammonia water and deionized water until the powders are completely dissolved, then adding thioacetamide to stir and dissolve until the mixed solution is a transparent liquid, immersing the substrate with TiO2 nanorods obtained in step (2) in the mixed solution to perform hydrothermal reaction, and obtaining a substrate containing vanadium oxide precursor; (4) annealing the substrate containing vanadium oxide precursor obtained in step (3) in an NH3 atmosphere, and obtaining the VN / TiO composite three-dimensional self-supporting electrode material after natural cooling to room temperature; The annealing treatment temperature in step (4) is 600-800℃, and the annealing treatment time is 1-3h.

2. The production method according to claim 1, characterized by, The Ti-containing compound is at least one of titanium tetrachloride, hexafluorotitanic acid, tetrabutyl titanate, isopropyl titanate and tetraethyl titanate.

3. The preparation method according to claim 1, characterized in that, The drying temperature in step (1) is 300-400℃.

4. The production method according to claim 1, characterized by, The volume ratio of deionized water to Ti-containing compound in step (1) is (40-50):

1.

5. The method of claim 1, wherein, The hydrothermal reaction temperature in step (2) is 140-180℃, and the hydrothermal reaction time is 3-6h; the annealing treatment temperature is 400-700℃, and the annealing treatment time is 0.5-2h.

6. The method of claim 1, wherein, The hydrothermal reaction temperature in step (3) is 160-180℃, and the hydrothermal reaction time is 3-6h.

7. The preparation method according to claim 1, characterized in that, The annealing treatment in step (4) has a heating rate of 5-10℃ / min.

8. The VN / TiO composite three-dimensional self-supporting electrode material for aqueous zinc ion batteries prepared by the preparation method in any one of claims 1-7.

9. Application of the VN / TiO composite three-dimensional self-supporting electrode material in claim 8 as a positive electrode material for zinc ion batteries.

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