V2O5 / MXene composite material with three-dimensional pillared structure as well as preparation method and application of V2O5 / MXene composite material

Abstract

The invention belongs to the field of composite nano materials, and discloses a V2O5 / MXene composite material with a three-dimensional pillared structure as well as a preparation method and application of the V2O5 / MXene composite material, which are used for solving the technical problem of limited electrochemical ion storage capacity caused by too small interlayer spacing of MXenes. The preparation method comprises the following steps: (1) adding MXene, a ground vanadium source and selenium powder into absolute ethyl alcohol, uniformly dispersing, and drying to obtain a mixture; and (2) heating and annealing the mixture obtained in the step (1) in a protective gas, and then cooling to room temperature to obtain the product. Through heat treatment, a V2O5 structure vertically grows in situ between MXene layers under the action of an inducer, and the purpose of stabilizing the interlayer spacing is achieved, so that a conductive network and an ion transmission path are optimized, and the electrochemical performance is effectively improved. When the V2O5 / MXene material prepared by the invention is applied to the aqueous zinc ion battery, relatively high specific capacity is shown.

Description

Technical Field

[0001] The present invention relates to the field of composite nanomaterials, and particularly to a three-dimensional composite material. Background Art

[0002] With the continuous growth of the demand for energy storage technologies, rechargeable aqueous zinc-ion batteries have gained the favor of researchers due to their low cost, operational safety, and environmental friendliness. In recent years, benefiting from the inherent advantages of zinc metal anodes, the promotion of aqueous zinc-ion batteries, such as having a high theoretical capacity (820 mAh / g) and a low reduction potential (-0.76 V) in an aqueous medium. In addition, the aqueous electrolyte under neutral or slightly acidic conditions provides a higher ionic conductivity than non-aqueous electrolytes, which is beneficial to improving the rate performance of aqueous zinc-ion batteries and has good compatibility with zinc metal anodes. However, the development of stable and efficient electrode materials still faces huge challenges. The main reason is that during the repeated zinc-ion insertion and extraction processes, obvious volume expansion and contraction occur, as well as irreversible phase change reactions, which induce the dissolution of active species and the structural collapse of electrode materials, resulting in slow diffusion kinetics and significant capacity decay, limiting the wide application of aqueous zinc-ion batteries in the commercial market.

[0003] In recent years, three-dimensional materials have become a research hotspot in the field of materials science due to their unique physical and chemical properties and extensive potential applications. Among them, MXene, as a new type of two-dimensional material, has rapidly attracted wide attention in the academic and industrial circles since it was first discovered by the research team at Drexel University in 2011. Two-dimensional MXenes are mainly prepared by selectively etching the "A" layer from layered ternary MAX precursors in a mixed solution of hydrofluoric acid or hydrochloric acid and lithium fluoride, where M, A, and X represent early transition metals (such as titanium, niobium, vanadium, molybdenum), group III-VI elements (such as aluminum, silicon, gallium), and carbon or nitrogen elements, respectively. The chemical composition of MXene is usually defined as M n+1 X n T x (n is 1-3), where T x refers to the surface end groups generated during the etching process (such as hydroxyl -OH and fluorine -F). Two-dimensional MXenes possess high conductivity, high specific surface area, good mechanical properties, and excellent electrochemical properties, especially showing great application potential in the field of energy storage.

[0004] However, limited by the interlayer van der Waals force, two-dimensional MXene is prone to agglomeration and stacking in practical applications, resulting in a reduced interlayer spacing, a decreased specific surface area, and a reduction in reaction sites, thereby affecting its physicochemical properties and even inducing performance failure. For example, when used in energy storage devices, the irreversible agglomeration and stacking of two-dimensional MXene will lead to a narrowing of the ion transport channels, a slowdown in ion transport kinetics, and a sharp decline in the capacity of the energy storage device. To solve this technical problem, in the prior art, other materials are grown on the surface or between the layers of MXene to further increase the interlayer spacing. For example, in the patents with publication numbers CN112018348A and CN114249322A, VO2 is combined with MXene, but VO2 mainly exists in the form of tiny particles; in the patent CN112018356A, V3Se4 mainly grows on the surface of MXene. Affected by size and surface preferential growth, these two existing forms mainly modify the surface of MXene and it is difficult to form an effective interlayer pillar effect. Summary of the Invention

[0005] Aiming at the technical problem of limited electrochemical ion storage capacity due to the too small interlayer spacing of MXenes, the present invention proposes a V2O5 / MXene composite material with a three-dimensional pillar structure, a preparation method thereof, and an application. This method uses heat treatment to in-situ vertically grow V2O5 between the MXene layers under the action of an inducer to achieve the purpose of stabilizing the interlayer spacing, thereby optimizing the conductive network and ion transport path, and effectively improving the electrochemical performance and cycle stability.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] A preparation method of a V2O5 / MXene composite material with a three-dimensional pillar structure, the steps are as follows:

[0008] (1) Add a vanadium source and selenium powder into a mortar and grind for 10 - 60 min;

[0009] (2) Add the MXene material and the vanadium source and selenium powder in step (1) into a 2 mL plastic tube filled with absolute ethanol, purge the plastic tube with nitrogen for 30 - 60 s to remove the air in the plastic tube, and ultrasonicate for 30 - 60 s to disperse it;

[0010] (3) Put the material in step (2) into a vacuum drying oven and dry at 50 - 60 °C for 1 - 2 h, and the vacuum degree of the vacuum drying oven is less than -0.01 Mpa;

[0011] (4) Place the material dried in step (3) into a quartz boat, put the quartz boat into a quartz tube with a diameter of 2.5 cm and a length of 15 cm, place the quartz tube into a tube furnace, repeat the evacuation and filling of the protective gas (argon or nitrogen) 4 - 6 times, and then carry out heat annealing treatment (heating and annealing) in the protective gas, and then cool to room temperature to obtain the V2O5 / MXene three-dimensional pillar-supported structure material. Selenium powder is used as an inducer to induce the vertical growth of V2O5 between the MXene layers. Specifically, during the reaction, when selenium powder is added and heated, selenium vapor is formed; the selenium vapor flows along the furnace tube under the action of argon or nitrogen, providing an environment of selenium vapor, filling the space between the MXene layers, and playing the role of an inducer at high temperature to induce the vertical growth of V2O5 between the MXene layers to form a three-dimensional pillar-supported structure material.

[0012] In the above step (2), the mass ratio of MXene, vanadium source, and selenium powder is 1:0.05 - 0.4:0.5 - 4.

[0013] Furthermore, in each liter of absolute ethanol in the above step (2), there are 80 - 150 g of MXene.

[0014] In the above step (2), the vanadium source is at least one of ammonium metavanadate, potassium metavanadate, sodium metavanadate, vanadyl sulfate, and vanadyl chloride; MXene is Ti3C2T x , V3C2T x , Nb2CT x and Mo2TiC2T x and at least one of them.

[0015] Furthermore, MXene is Ti3C2T x or V3C2T x , T x is a surface functional group -O, -F, or -OH.

[0016] In the above step (4), the heat annealing treatment is to heat to 400 - 600 °C at a heating rate of 8 - 12 °C / min, and the holding time is 1 - 5 h. For example, the heating rate is 8 - 10 °C / min, the heating rate is 10 - 12 °C / min, the heating rate is 9 - 11 °C / min, or the heating rate is 8 °C / min, 9 °C / min, 10 °C / min, 11 °C / min, or 12 °C / min, etc. Heat to 400 - 600 °C at any of the above heating rates, such as 400 °C, 450 °C, 500 °C, 550 °C, or 600 °C, and the holding (annealing treatment) time is 1 - 5 h, such as 1 h, 2 h, 3 h, 4 h, or 5 h, etc.

[0017] Further, during the cooling process in step (4) above, the cooling rate is 15 - 20 °C / min. For example, the cooling rate is 15 - 17 °C / min; the cooling rate is 17 - 20 °C / min; the cooling rate is 15 °C / min, 16 °C / min, 17 °C / min, 18 °C / min, 19 °C / min, or 20 °C / min. The protective gas is argon or nitrogen, and the gas flow rate is 6 - 120 mL / min. For example, the gas velocity is 6 - 40 mL / min; the gas velocity is 50 - 80 mL / min; the gas velocity is 90 - 120 mL / min; the gas velocity is 40 - 90 mL / min; the gas velocity is 6 mL / min, 18 mL / min, 24 mL / min, 30 mL / min, 36 mL / min, 42 mL / min, 48 mL / min, 54 mL / min, 60 mL / min, 90 mL / min, 120 mL / min.

[0018] Using the above preparation method, a V2O5 / MXene composite material with a three-dimensional pillar-supported structure can be prepared.

[0019] Application of the above V2O5 / MXene composite material in zinc-ion batteries.

[0020] A zinc-ion battery, the positive electrode of which contains the above V2O5 / MXene composite material.

[0021] The beneficial effects of the present invention are:

[0022] (1) The present invention provides a novel V2O5 / MXene composite material with a three-dimensional pillar-supported structure. By introducing V2O5 into MXene, the structural stability of MXene is enhanced and the interfacial stability of MXene is improved. On the one hand, in the present invention, selenium powder forms selenium gas during the high-temperature heating process, which serves as an inducer to induce the vertical growth of V2O5 between the MXene layers, providing an interlayer pillar support effect, avoiding the agglomeration and stacking of MXene layers, expanding the interlayer spacing, enhancing the structural stability of MXene, and being beneficial to the insertion and extraction of electrochemical ions (such as zinc ions). On the other hand, selenium induces the in-situ growth of V2O5 to form a unique Ti-O-V interfacial chemical bond, improving the interfacial stability of MXene.

[0023] (2) The V2O5 / Mxene composite material prepared by the present invention has a synergistic effect and can improve the zinc storage capacity of zinc-ion batteries. Specifically, at a current density of 100 mA / g, for the zinc-ion battery assembled with the material prepared in Example 1 of the present invention, its reversible specific capacity is 350 mAh / g, which is much higher than the battery performance of V2O5 / MXene assembled by other methods.

[0024] (3) The composite material of the present invention is safer during the entire synthesis process, has high production efficiency, a simple preparation method, high cost performance, and is easy to prepare on a large scale. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 SEM image of V2O5 / MXene with a three-dimensional pillar structure prepared in Example 1.

[0027] Figure 2 X-ray photoelectron spectroscopy diagram of V2O5 / MXene with a three-dimensional pillar structure prepared in Example 1.

[0028] Figure 3 X-ray diffraction pattern of V2O5 / MXene with a three-dimensional pillar structure prepared in Example 1.

[0029] Figure 4 Galvanostatic charge-discharge performance diagram of V2O5 / MXene with a three-dimensional pillar structure prepared in Example 1.

[0030] Figure 5 Galvanostatic charge-discharge performance diagram of V2O5 without MXene prepared in Comparative Example 1.

[0031] Figure 6 Galvanostatic charge-discharge performance diagram of V2O5 / MXene prepared without selenium inducer in Comparative Example 2.

[0032] Figure 7 Galvanostatic charge-discharge performance diagram of V2O5 / MXene prepared with sulfur inducer in Comparative Example 3. Detailed Embodiments

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0034] Example 1

[0035] A preparation method of a V2O5 / MXene composite material with a three-dimensional pillar structure in this embodiment is as follows:

[0036] (1) Weigh 15 mg of ammonium metavanadate and 25 mg of selenium powder and add them to a mortar for manual grinding for 10 min.

[0037] (2) Weigh 50 mg of MXene (Ti3C2T x ) Add the ground material and Ti3C2T x together into a 2 mL plastic tube containing 0.5 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then sonicate for 30 - 60 s.

[0038] (3) Put the sample in step (2) into a vacuum drying oven (60 °C) to vacuum dry for 2 h, and the vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0039] (4) Put the dried material in step (3) into a quartz boat, put the quartz boat into a quartz tube with a diameter of 2.5 cm, and then put the quartz tube into a tube furnace. Repeat the process of vacuum pumping and nitrogen filling five times. Each time the vacuum pumping time is 5 min, and the nitrogen rate is 60 mL / min for 2 min. The tube furnace is filled with high-purity nitrogen with a flow rate of 15 mL / min, heated to 550 °C at a heating rate of 10 °C / min, annealed for 2 h, and then cooled to room temperature at a cooling rate of 17.5 °C / min to obtain V2O5 / MXene with a three-dimensional pillar structure.

[0040] Figure 1 is the scanning electron microscope image and the schematic diagram of the pillar structure, indicating that V2O5 / MXene has an obvious interlayer pillar structure, that is, V2O5 grows vertically between the MXene layers. Figure 2 is the X-ray photoelectron spectroscopy test result, indicating that a Ti-O-V interfacial chemical bond is formed between V2O5 and MXene. Figure 3 is the X-ray diffraction test result, indicating that the state of vanadium in the product exists in the form of V2O5.

[0041] Example 2

[0042] A preparation method of a V2O5 / MXene composite material with a three-dimensional pillar structure in this embodiment is as follows:

[0043] (1) Weigh 15 mg of ammonium metavanadate and 50 mg of selenium powder and add them to a mortar for manual grinding for 10 min.

[0044] (2) Weigh 50 mg of MXene (Ti3C2T x ) Add the ground material and Ti3C2T xAdd them together into a 2 mL plastic tube containing 0.5 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then sonicate for 30 - 60 s.

[0045] (3) Put the sample from step (2) into a vacuum drying oven (60 °C), evacuate and dry for 2 h, and the vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0046] (4) Put the dried material from step (3) into a quartz boat, put the quartz boat into a quartz tube with a diameter of 2.5 cm, then put the quartz tube into a tube furnace, repeat evacuating and filling with nitrogen five times, with each evacuation time being 5 min and the nitrogen rate being 60 mL / min for 2 min. Pass high-purity nitrogen into the tube furnace at a flow rate of 15 mL / min, heat to 550 °C at a heating rate of 10 °C / min, anneal for 2 h, and then cool to room temperature at a cooling rate of 17.5 °C / min to obtain V2O5 / MXene with a three-dimensional pillar-supported structure.

[0047] Example 3

[0048] A preparation method of a V2O5 / MXene composite material with a three-dimensional pillar-supported structure in this example is as follows:

[0049] (1) Weigh 15 mg of ammonium metavanadate and 100 mg of selenium powder, add them together into a mortar and grind manually for 10 min.

[0050] (2) Weigh 50 mg of MXene (Ti3C2T x ) Add the ground material and Ti3C2T x together into a 2 mL plastic tube containing 0.5 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then sonicate for 30 - 60 s.

[0051] (3) Put the sample from step (2) into a vacuum drying oven (60 °C), evacuate and dry for 2 h, and the vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0052] (4) Put the dried material from step (3) into a quartz boat, put the quartz boat into a quartz tube with a diameter of 2.5 cm, then put the quartz tube into a tube furnace, repeat evacuating and filling with nitrogen five times, with each evacuation time being 5 min and the nitrogen rate being 60 mL / min for 2 min. Pass high-purity nitrogen into the tube furnace at a flow rate of 15 mL / min, heat to 550 °C at a heating rate of 10 °C / min, anneal for 2 h, and then cool to room temperature at a cooling rate of 17.5 °C / min to obtain V2O5 / MXene with a three-dimensional pillar-supported structure.

[0053] Example 4

[0054] A preparation method of a V2O5 / MXene composite material with a three-dimensional pillar structure in this embodiment is as follows:

[0055] (1) Weigh 2.5 mg of potassium metavanadate and 200 mg of selenium powder and add them to a mortar for manual grinding for 60 min.

[0056] (2) Weigh 50 mg of MXene (Ti3C2T x ) Add the ground material and Ti3C2T x together into a 2 mL plastic tube containing 0.62 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then ultrasonicate for 30 - 60 s.

[0057] (3) Put the sample in step (2) into a vacuum drying oven (60 °C) and vacuum dry it for 1 h. The vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0058] (4) Put the dried material in step (3) into a quartz boat, put the quartz boat into a quartz tube with a diameter of 2.5 cm, and then put the quartz tube into a tube furnace. Repeat the vacuum pumping and nitrogen filling five times. Each vacuum pumping time is 5 min, and the nitrogen rate is 60 mL / min for 2 min. The tube furnace is filled with high-purity nitrogen with a flow rate of 120 mL / min, heated to 600 °C at a heating rate of 8 °C / min, annealed for 1 h, and then cooled to room temperature at a cooling rate of 15 °C / min to obtain V2O5 / MXene with a three-dimensional pillar structure.

[0059] Example 5

[0060] A preparation method of a V2O5 / MXene composite material with a three-dimensional pillar structure in this embodiment is as follows:

[0061] (1) Weigh 20 mg of vanadyl sulfate and 100 mg of selenium powder and add them to a mortar for manual grinding for 60 min.

[0062] (2) Weigh 50 mg of MXene (Ti3C2T x ) Add the ground material and Ti3C2T x together into a 2 mL plastic tube containing 0.33 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then ultrasonicate for 30 - 60 s.

[0063] (3) Put the sample in step (2) into a vacuum drying oven (50 °C) and vacuum dry it for 2 h. The vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0064] (4) Put the material obtained after drying in step (3) into a quartz boat, place the quartz boat into a quartz tube with a diameter of 2.5 cm, then put the quartz tube into a tube furnace. Repeat the process of vacuum pumping and nitrogen filling five times. Each time, the vacuum pumping time is 5 min, and the nitrogen rate is 60 mL / min for 2 min. High-purity nitrogen is introduced into the tube furnace at a flow rate of 80 mL / min, heated to 400 °C at a heating rate of 12 °C / min, annealed for 5 h, and then cooled to room temperature at a cooling rate of 20 °C / min to obtain V2O5 / MXene with a three-dimensional pillar structure.

[0065] Example 6

[0066] A method for preparing a V2O5 / MXene composite material with a three-dimensional pillar structure in this example is as follows:

[0067] (1) Weigh 15 mg of ammonium metavanadate and 150 mg of selenium powder and add them to a mortar for manual grinding for 10 min.

[0068] (2) Weigh 50 mg of MXene (Ti3C2T x ) Add the ground material and Ti3C2T x together into a 2 mL plastic tube containing 0.5 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then ultrasonicate for 30 - 60 s.

[0069] (3) Put the sample in step (2) into a vacuum drying oven (60 °C) to complete vacuum drying for 1 h. The vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0070] (4) Put the material obtained after drying in step (3) into a quartz boat, place the quartz boat into a quartz tube with a diameter of 2.5 cm, then put the quartz tube into a tube furnace. Repeat the process of vacuum pumping and nitrogen filling five times. Each time, the vacuum pumping time is 5 min, and the nitrogen rate is 60 mL / min for 2 min. High-purity nitrogen is introduced into the tube furnace at a flow rate of 6 mL / min, heated to 500 °C at a heating rate of 10 °C / min, annealed for 3 h, and then cooled to room temperature at a cooling rate of 18 °C / min to obtain V2O5 / MXene with a three-dimensional pillar structure.

[0071] Example 7

[0072] A method for preparing a V2O5 / MXene composite material with a three-dimensional pillar structure in this example is as follows:

[0073] (1) Weigh 15 mg of ammonium metavanadate and 25 mg of selenium powder and add them to a mortar for manual grinding for 10 min.

[0074] (2) Weigh 50 mg of MXene (V3C2T x)Add the ground material and V3C2T x together into a 2 mL plastic tube containing 0.5 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then sonicate for 30 - 60 s.

[0075] (3) Put the sample from step (2) into a vacuum drying oven (60 °C), evacuate and dry for 2 h, with the vacuum degree of the vacuum drying oven less than -0.1 Mpa.

[0076] (4) Put the dried material from step (3) into a quartz boat, place the quartz boat into a quartz tube with a diameter of 2.5 cm, then put the quartz tube into a tube furnace, repeat the evacuation and nitrogen filling five times, with each evacuation time being 5 min and the nitrogen rate being 60 mL / min for 2 min. The tube furnace is filled with high-purity nitrogen, with a flow rate of 15 mL / min, heated to 550 °C at a heating rate of 10 °C / min, annealed for 2 h, and then cooled to room temperature at a cooling rate of 17.5 °C / min to obtain V2O5 / MXene with a three-dimensional pillar-supported structure.

[0077] Example 8

[0078] A method for preparing a V2O5 / MXene composite material with a three-dimensional pillar-supported structure in this example is as follows:

[0079] (1) Weigh 15 mg of ammonium metavanadate and 25 mg of selenium powder, add them together into a mortar and grind manually for 10 min.

[0080] (2) Weigh 50 mg of MXene (Nb2CT x ) Add the ground material and Nb2CT x together into a 2 mL plastic tube containing 0.5 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then sonicate for 30 - 60 s.

[0081] (3) Put the sample from step (2) into a vacuum drying oven (60 °C), evacuate and dry for 2 h, with the vacuum degree of the vacuum drying oven less than -0.1 Mpa.

[0082] (4) Put the dried material from step (3) into a quartz boat, place the quartz boat into a quartz tube with a diameter of 2.5 cm, then put the quartz tube into a tube furnace, repeat the evacuation and nitrogen filling five times, with each evacuation time being 5 min and the nitrogen rate being 60 mL / min for 2 min. The tube furnace is filled with high-purity nitrogen, with a flow rate of 15 mL / min, heated to 550 °C at a heating rate of 10 °C / min, annealed for 2 h, and then cooled to room temperature at a cooling rate of 17.5 °C / min to obtain V2O5 / MXene with a three-dimensional pillar-supported structure.

[0083] Example 9

[0084] A preparation method of a V2O5 / MXene composite material with a three-dimensional pillar structure in this embodiment is as follows:

[0085] (1) Weigh 15 mg of ammonium metavanadate and 25 mg of selenium powder and add them to a mortar for manual grinding for 10 min.

[0086] (2) Weigh 50 mg of MXene (Mo2TiC2T x ) Add the ground material and Mo2TiC2T x together into a 2 mL plastic tube containing 0.5 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then sonicate for 30 - 60 s.

[0087] (3) Put the sample in step (2) into a vacuum drying oven (60 °C), evacuate and dry for 2 h, and the vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0088] (4) Put the dried material in step (3) into a quartz boat, put the quartz boat into a quartz tube with a diameter of 2.5 cm, and then put the quartz tube into a tube furnace. Repeat the evacuation and nitrogen filling five times, with each evacuation time being 5 min and the nitrogen rate being 60 mL / min for 2 min. The tube furnace is filled with high-purity nitrogen with a flow rate of 15 mL / min, heated to 550 °C at a heating rate of 10 °C / min, annealed for 2 h, and then cooled to room temperature at a cooling rate of 17.5 °C / min to obtain V2O5 / MXene with a three-dimensional pillar structure.

[0089] Comparative Example 1

[0090] A preparation method of a V2O5 material in this comparative example, which is different from Example 2, is that no MXene is added. The specific steps are as follows:

[0091] (1) Weigh 15 mg of ammonium metavanadate and 50 mg of selenium powder and add them to a mortar for manual grinding for 10 min.

[0092] (2) Weigh the ground material and add it to a 2 mL plastic tube containing 0.5 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then sonicate for 30 - 60 s.

[0093] (3) Put the sample in step (2) into a vacuum drying oven (60 °C), evacuate and dry for 2 h, and the vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0094] (4) Put the material obtained after drying in step (3) into a quartz boat, place the quartz boat into a quartz tube with a diameter of 2.5 cm, then put the quartz tube into a tube furnace. Repeat the procedures of vacuum pumping and nitrogen filling five times. Each time, the vacuum pumping time is 5 min, and the nitrogen rate is 60 mL / min for 2 min. High-purity nitrogen is introduced into the tube furnace at a flow rate of 15 mL / min, heated to 550 °C at a heating rate of 10 °C / min, annealed for 2 h, and then cooled to room temperature at a cooling rate of 17.5 °C / min to obtain the V2O5 material.

[0095] Comparative Example 2

[0096] A preparation method of a V2O5 / MXene composite material in this comparative example is different from that in Example 1 in that no selenium powder is added. The specific steps are as follows:

[0097] (1) Weigh 15 mg of ammonium metavanadate and add it to a mortar for manual grinding for 10 min.

[0098] (2) Weigh 50 mg of MXene (Ti3C2T x ) Add the ground material and Ti3C2T x together into a 2 mL plastic tube containing 0.5 mL of absolute ethanol, purge the plastic tube with nitrogen for 30 s, and then sonicate for 30 - 60 s.

[0099] (3) Put the sample in step (2) into a vacuum drying oven (60 °C) to complete vacuum drying for 2 h. The vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0100] (4) Put the material obtained after drying in step (3) into a quartz boat, place the quartz boat into a quartz tube with a diameter of 2.5 cm, then put the quartz tube into a tube furnace. Repeat the procedures of vacuum pumping and nitrogen filling five times. Each time, the vacuum pumping time is 5 min, and the nitrogen rate is 60 mL / min for 2 min. High-purity nitrogen is introduced into the tube furnace at a flow rate of 15 mL / min, heated to 550 °C at a heating rate of 10 °C / min, annealed for 2 h, and then cooled to room temperature at a cooling rate of 17.5 °C / min to obtain V2O5 / MXene.

[0101] Comparative Example 3

[0102] A preparation method of a V2O5 / MXene composite material in this comparative example is different from that in Example 1 in that sulfur powder is used as an inducer. The specific steps are as follows:

[0103] (1) Weigh 15 mg of ammonium metavanadate and 25 mg of sulfur powder together and add them to a mortar for manual grinding for 10 min.

[0104] (2) Weigh 50 mg of MXene (Ti3C2T x) Add the ground material and Ti3C2T x together into a 2 mL plastic tube containing 0.5 mL of absolute ethanol. Purge the plastic tube with nitrogen for 30 s, and then sonicate for 30 - 60 s.

[0105] (3) Place the sample from step (2) into a vacuum drying oven (60 °C), evacuate and dry for 2 h. The vacuum degree of the vacuum drying oven is less than -0.1 Mpa.

[0106] (4) Place the dried material from step (3) into a quartz boat, put the quartz boat into a quartz tube with a diameter of 2.5 cm, and then place the quartz tube into a tube furnace. Repeat the evacuation and nitrogen filling five times. Each evacuation time is 5 min, and the nitrogen rate is 60 mL / min for 2 min. Pass high-purity nitrogen into the tube furnace at a flow rate of 15 mL / min, heat to 550 °C at a heating rate of 10 °C / min, anneal for 2 h, and then cool to room temperature at a cooling rate of 17.5 °C / min to obtain V2O5 / MXene.

[0107] Application Example

[0108] Apply the V2O5 / MXene composite materials prepared in Examples 1 - 6 of the present invention, the V2O5 material prepared in Comparative Example 1, and the V2O5 / MXene composite materials prepared in Comparative Examples 2 - 3 to zinc ion batteries. The specific process for preparing the zinc ion batteries is as follows:

[0109] Mix the V2O5 / MXene three-dimensional pillar-supported structure material, polyvinylidene fluoride, and carbon black in a mass ratio of 8:1:1, add an appropriate amount of N-methylpyrrolidone, and then put it into a mortar and grind for 30 min to form a uniform slurry. Coat the slurry on a titanium foil current collector, dry in vacuum at 60 °C for 12 h, and press into a positive electrode plate for the zinc ion battery. Use a pure zinc sheet as the counter electrode. The process for preparing the batteries using the materials in Comparative Examples 1 - 3 is the same as above. Conduct electrochemical tests using a button-type half-cell.

[0110] Conduct electrochemical performance tests on the above-prepared zinc ion batteries. Use a battery tester to perform constant current charge-discharge and stability tests. The current density used is 100 mA / g, the highest charging voltage is 1.5 V, and the lowest discharging voltage is 0.2 V. The test results are shown in Table 1.

[0111] Table 1. Comparison of material compositions and specific capacity data in Examples and Comparative Examples

[0112] Project Material composition Inducer Reversible specific capacity (mAh / g) Example 1 <![CDATA[V2O5 / Ti3C2T x MXene]]> Selenium powder 350 Example 2 <![CDATA[V2O5 / Ti3C2T x MXene]]> Selenium powder 341 Example 3 <![CDATA[V2O5 / Ti3C2T x MXene]]> Selenium powder 314 Example 4 <![CDATA[V2O5 / Ti3C2T x MXene]]> Selenium powder 282 Example 5 <![CDATA[V2O5 / Ti3C2T x MXene]]> Selenium powder 309 Example 6 <![CDATA[V2O5 / Ti3C2T x MXene]]> Selenium powder 299 Example 7 <![CDATA[V2O5 / V3C2T x MXene]]> Selenium powder 321 Example 8 <![CDATA[V2O5 / Nb2CT x MXene]]> Selenium powder 300 Example 9 <![CDATA[V2O5 / Mo2TiC2T x MXene]]> Selenium powder 287 Comparative example 1 <![CDATA[V2O5]]> Selenium powder 170 Comparative example 2 <![CDATA[V2O5 / MXene]]> None 142 Comparative example 3 <![CDATA[V2O5 / MXene]]> Sulfur powder 139

[0113] As can be seen from Table 1, compared with adding no inducer or using other inducers (such as sulfur), the three-dimensional pillared V2O5 / MXene material obtained under the action of a selenium inducer shows a higher reversible specific capacity, indicating that the three-dimensional pillared structure obtained by using a selenium inducer in the design of this scheme is conducive to the insertion and extraction of zinc ions and can improve the specific capacity of zinc-ion batteries.

[0114] Figure 4 It is the galvanostatic charge-discharge performance diagram assembled with the V2O5 / MXene composite material prepared in Example 1. From Figure 4 it can be seen that its reversible specific capacity is 350 mAh / g.

[0115] Figure 5 It is the galvanostatic charge-discharge performance diagram of the V2O5 material without MXene prepared in Comparative Example 1. Electrochemical tests show that the discharge capacity is 170 mAh / g.

[0116] Figure 6 It is the galvanostatic charge-discharge performance diagram of the V2O5 / MXene material prepared in Comparative Example 2 without a selenium inducer. Electrochemical tests show that the discharge capacity is 142 mAh / g.

[0117] Figure 7 It is the galvanostatic charge-discharge performance diagram of the V2O5 / MXene material prepared with a sulfur inducer in Comparative Example 3. Electrochemical tests show that the discharge capacity is 139 mAh / g.

[0118] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a V2O5 / MXene composite material with a three-dimensional pillar structure, characterized in that, The steps are as follows: (1) Add MXene, the ground vanadium source, and selenium powder into absolute ethanol, ultrasonically disperse them evenly, and obtain a mixture after drying; (2) Heat and anneal the mixture obtained in step (1) in a protective gas, and then cool it to room temperature to obtain the product.

2. The preparation method of the V2O5 / MXene composite material with a three-dimensional pillar structure according to claim 1, characterized in that, In step (1), the mass ratio of MXene, the vanadium source, and selenium powder is 1:0.05 - 0.4:0.5 - 4.

3. The preparation method of the V2O5 / MXene composite material with a three-dimensional pillar structure according to claim 2, characterized in that, In step (1), there are 80 - 150 g of MXene in each liter of absolute ethanol.

4. The preparation method of the V2O5 / MXene composite material with a three-dimensional pillar structure according to any one of claims 1-3, characterized in that, In the step (1), the vanadium source is at least one of ammonium metavanadate, potassium metavanadate, sodium metavanadate, vanadyl sulfate, and vanadyl chloride; the MXene is at least one of Ti3C2T x , V3C2T x , Nb2CT x and Mo2TiC2T x among others.

5. The preparation method of the V2O5 / MXene composite material with a three-dimensional pillar structure according to claim 4, characterized in that, In step (1), the grinding time is 10 - 60 min; the drying temperature is 50 - 60 °C, and the drying time is 1 - 2 h.

6. The preparation method of the V2O5 / MXene composite material with a three-dimensional pillar structure according to claim 5, characterized in that, In step (2), the heating rate of the heat treatment for heating and annealing is 8 - 12 °C / min, the temperature is 400 - 600 °C, and the time is 1 - 5 h.

7. The preparation method of the V2O5 / MXene composite material with a three-dimensional pillar structure according to claim 6, characterized in that, In the cooling process of step (2), the cooling rate is 15 - 20 °C / min, the protective gas is argon or nitrogen, and the gas flow rate is 6 - 120 mL / min.

8. The V2O5 / MXene composite material prepared by the preparation method of the V2O5 / MXene composite material with a three-dimensional pillar structure according to claim 1.

9. The application of the V2O5 / MXene composite material according to claim 8 in a zinc-ion battery.

10. A zinc-ion battery, characterized in that, The positive electrode of the zinc-ion battery contains the V2O5 / MXene composite material according to claim 8.

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