V6O13 nano material as well as preparation method and application thereof

Abstract

The invention discloses a V6O13 nano material and a preparation method and application thereof, and belongs to the technical field of aqueous zinc ion batteries, the preparation method of the V6O13 nano material comprises the following steps: taking V2O5 as a vanadium source, and adopting a hydrothermal method to prepare an intermediate product; and the intermediate product is subjected to annealing treatment, and the V6O13 nanometer material is obtained. According to the preparation method disclosed by the invention, a hydrothermal-annealing synergistic strategy is adopted, firstly, an intermediate product is prepared by taking V2O5 as a vanadium source and adopting a hydrothermal method, and then, the V6O13 nano material with more complete lattice arrangement is obtained through high-temperature annealing, so that higher battery capacity and more stable long cycle life are realized, and a new scheme is provided for research on an aqueous zinc ion battery positive electrode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of aqueous zinc ion batteries, and particularly relates to a V6O 13 Nanomaterials, their preparation methods and applications. Background Art

[0002] Aqueous zinc-ion batteries (AZIBs) are a hot topic in the energy storage field. Their low cost, safety, and harmlessness meet the requirements of green, environmentally friendly, and sustainable development. Current research on cathode materials for aqueous zinc-ion batteries focuses primarily on vanadium- and manganese-based materials. The advantages of vanadium-based materials lie in their diverse valence states and open structures. Within their crystal structures, VO bonds form diverse layered or tunnel-like structures through shared vertices, shared edges, and shared surfaces. This diverse connection enhances the stability and configurational diversity of vanadium-based materials.

[0003] The larger layered structure of vanadium-based materials can be Zn 2+ Provide sufficient transmission channels during the reversible redox reaction. Taking V2O5 as an example, its unit cell parameters are And Zn 2+ The radius is Theoretically, V2O5 can be Zn 2+ However, since the electrolyte used in aqueous zinc-ion battery system is water as solvent and usually exhibits weak acidity, water molecules have strong polarity and will react with Zn produced by oxidation at the negative electrode. 2+ Forming a solvation shell structure to generate hydrated zinc ions [Zn(H2O)6] 2+ Its radius is approximately During the redox process [Zn(H2O)6] 2+ It will produce a strong electrostatic effect with the positive electrode material, slowing down the diffusion dynamics of ions; the larger radius in the crystal structure embedded in the positive electrode material will cause the crystal of the material to be squeezed and expanded, resulting in irreversible structural collapse. Summary of the Invention

[0004] In view of the above technical problems, the present invention proposes a V6O 13 Nanomaterials and their preparation methods and applications, namely, the present invention adopts a hydrothermal-annealing synergistic strategy, firstly using V2O5 as a vanadium source to prepare an intermediate product by a hydrothermal method, and then annealing at high temperature to obtain a V6O with a more complete lattice arrangement. 13 Nanomaterials achieve higher battery capacity and more stable long cycle life, providing a new solution for the research of positive electrode materials for aqueous zinc-ion batteries.

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

[0006] One of the technical solutions of the present invention:

[0007] A V6O 13 The method for preparing a nanomaterial comprises the following steps:

[0008] The intermediate product was prepared by hydrothermal method using V2O5 as vanadium source;

[0009] The intermediate product is annealed to obtain the V6O 13 Nanomaterials.

[0010] Optionally, the specific steps of the hydrothermal method are:

[0011] V2O5, polyvinyl pyrrolidone and ethylene glycol are added to deionized water and stirred evenly, and then hydrochloric acid is added dropwise thereto and stirred evenly again, and then a hydrothermal reaction is carried out in a reactor, and then centrifuged, washed and dried in sequence to obtain an intermediate product.

[0012] Beneficial effect: The present invention proposes a method based on V6O 13 The preparation method of nanomaterials and their application in aqueous zinc-ion battery cathode materials, through the hydrothermal-annealing synergistic strategy to optimize the material structure, significantly improve its electrochemical performance and cycle stability. Among them, V2O5 has good solubility and reactivity, and is easy to form vanadium-containing precursors under acidic conditions, which is the basis for the subsequent generation of V6O 13 Provide sufficient and stable vanadium source; it is beneficial to control the V content in the product 5+ / V 4+ ratio, thereby regulating the electronic conductivity and redox activity of the material; PVP can effectively regulate the crystal growth direction, inhibit particle agglomeration, and help form a uniform nanostructure; improve the specific surface area and pore structure of the product, enhance the interface contact between the electrode material and the electrolyte, and improve the ion diffusion efficiency; ethylene glycol is used as a reducing agent and solvent. In the hydrothermal system, ethylene glycol can partially reduce high-valent vanadium species and promote the conversion of V6O 13 The formation of an intermediate phase; at the same time, as a high-boiling point solvent, it helps to maintain the stability of the system and improve the controllability of the reaction; hydrochloric acid adjusts the pH value of the solution to acidic conditions that are conducive to the dissolution of V2O5 and the hydrolysis and polymerization of vanadium species; controlling the appropriate acidity can affect the crystal structure and crystallinity of the final product.

[0013] Furthermore, the usage ratio of V2O5, polyvinyl pyrrolidone, ethylene glycol, deionized water and hydrochloric acid is: 3mmol: 200mg: 1mL: 60ml: 1ml.

[0014] Furthermore, the concentration of the hydrochloric acid is 2 mol L -1 .

[0015] Furthermore, the conditions during the hydrothermal reaction are: keeping the temperature at 180° C. for 12 hours in an electric forced air drying oven.

[0016] Beneficial effect: Under the hydrothermal reaction conditions specified in the present invention, V6O with a preliminary crystal structure can be formed. 13 Intermediates; if the temperature is too low, it is difficult to form an ordered structure, while if the temperature is too high, it may lead to grain coarsening or the formation of by-products.

[0017] Furthermore, the centrifugal conditions are: at 5000 r min -1 Centrifuge for 3 minutes.

[0018] Furthermore, the conditions during the drying process are: vacuum drying at 70° C. for 24 hours.

[0019] Optionally, the annealing process is carried out under the following conditions: 3°C min -1 Heat to 200-400°C and keep warm for 2 hours.

[0020] Beneficial effects: This annealing condition can remove part of the crystal water in the material without causing structural collapse; it can also increase V 5+ ratio, significantly improving the crystallinity of the (200) crystal plane, making the lattice arrangement more orderly, and enhancing the ion diffusion kinetics.

[0021] Furthermore, the annealing process is carried out under the following conditions: 3°C min in air atmosphere. -1 Heat to 200°C and keep warm for 2h.

[0022] The second technical solution of the present invention:

[0023] A V6O 13 The nanomaterial is prepared by the above preparation method.

[0024] The third technical solution of the present invention:

[0025] The above V6O 13 Application of nanomaterials as aqueous zinc ion positive electrode materials.

[0026] The fourth technical solution of the present invention:

[0027] An aqueous zinc ion battery, the positive electrode of which is the above-mentioned V6O 13 Nanomaterials.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] The present invention adopts a hydrothermal-annealing synergistic strategy, firstly using a simple hydrothermal method to prepare V6O 13Then, the material was annealed in a muffle furnace to remove part of the crystal water and change the V6O 13 V 5+ / V 4+ ratio, confirmed by electrochemical experimental data and detailed characterization, for V6O 13 The optimization of the material structure inhibits its structural collapse, enhances the stability of the material during the cycle process, and improves the specific capacity of the material.

[0030] First, XRD confirmed that after annealing at 200℃, V6O 13 The defects disappear, improving the crystallinity of the 200 crystal plane, making V6O 13 The crystal structure is more orderly; TG confirmed that the unit mass of V6O increased after annealing at 200℃ 13 XPS confirmed that annealing at 200℃ increased the V6O 13 Medium V 5+ % of the total.

[0031] Secondly, the battery cycle test, rate performance test, CV test and EIS test at different current densities confirmed that the 200℃ annealing treatment improved the Zn 2+ The diffusion rate of V6O 13 -200 material as a positive electrode material for aqueous zinc ion batteries has better electrochemical performance than other comparison samples. -1 The highest specific capacity at current density is 407 mAh g -1 , the capacity retention rate reaches 95.3%; 2Ag -1 The optimal specific capacity is 360 mAh g -1 After 1000 cycles, it still has 332mAh g -1 , capacity retention rate is 92%; 5Ag -1 The capacity retention rate is 75% after 4000 cycles at the same current density.

[0032] In summary, the V6O prepared by the present invention 13 Nanomaterials (especially V6O 13 -200) has excellent electrochemical performance and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 XRD spectra (a) and local XRD spectra (b) of different samples;

[0035] Figure 2 SEM images of different samples, where (a) is V6O 13 , (b) is V6O 13 -200; (c) is V6O 13 -300, (d) is V6O 13 -500;

[0036] Figure 3 TEM images of different samples, where (a) is V6O 13 , (b) is V6O 13 -200; (c) is V6O 13 -300, (d) is V6O 13 -500;

[0037] Figure 4 (a) is the overall projection TEM image, (b) is the V6O 13 -200 sample EDS-mapping diagram, (c) is V element, (d) is O element;

[0038] Figure 5 V6O 13 With V6O 13 -200 XPS spectrum, where (a) is V 2p; (b) is O1s;

[0039] Figure 6 V6O 13 and V6O 13 -200 EPR curve;

[0040] Figure 7 (a) is V6O 13 / V6O 13 -200 N2 adsorption-desorption isotherm, (b) pore size distribution curve;

[0041] Figure 8 V6O 13 / V6O 13 -200 thermogravimetric curve, where (a) is V6O 13 , (b) is V6O 13 -200;

[0042] Figure 9 (a) is the sample at a current density of 0.5A -1 Cyclic test diagram; (b) V6O 13 The charge / discharge curves of the electrodes corresponding to different cycle times; (c) is V6O 13-200 electrode charge / discharge curves corresponding to different cycle times; (d) is the rate performance test diagram; (e) is the V6O 13 Charge and discharge curves of the electrode at different current densities; (f) is V6O 13 -200 electrode charge and discharge curves at different current densities;

[0043] Figure 10 V6O 13 -200 electrode at a current density of 2Ag -1 Cyclic performance test diagram;

[0044] Figure 11 V6O 13 -200 electrode at a current density of 5Ag -1 Cyclic performance test diagram;

[0045] Figure 12 (a) and (b) are V6O 13 With V6O 13 -200 electrodes at 0.2-1.0 mV s -1 CV curves; (c) and (d) are fitted b values; (e) and (f) are the CV curves at 0.2 mV s -1 V6O 13 With V6O 13 -200 capacitance contribution;

[0046] Figure 13 (a) and (b) are V6O 13 / V6O 13 -200 electrode pseudocapacitance contribution at different scan rates;

[0047] Figure 14 (a) is V6O 13 / V6O 13 -200 electrode EIS spectrum; (b) Z ' With ω -1 / 2 Linear fitting of the function; DETAILED DESCRIPTION

[0048] 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.

[0049] 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. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0050] 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.

[0051] 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.

[0052] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0053] Unless otherwise specified, the "room temperature" in the present invention refers to 20-30°C.

[0054] The "parts" described in the present invention, unless otherwise specified, refer to parts by mass.

[0055] The raw materials used in the present invention were all purchased from the market. The main reagents used in the examples are shown in Table 1.

[0056] Table 1

[0057]

[0058] Among them, the water used in the experiment was ultrapure water, and the drugs used were not further treated before the experiment.

[0059] The technical solution of the present invention is further illustrated by the following examples.

[0060] Example 1

[0061] A V6O with mixed valence 13 The method for preparing a nanomaterial comprises the following steps:

[0062] Step 1: First, add 3mmol V2O5, 200mg polyvinylpyrrolidone and 1mL ethylene glycol into 60ml deionized water and stir for 30min, then add 1ml 2mol L -1 HCl, stirred again for 30 min and then transferred into a 100 ml Teflon reactor, kept at 180 ° C in an electric blast drying oven for 12 h, cooled to room temperature, and then heated at 5000 r min -1 The product was collected after centrifugation for 3 minutes, and then washed alternately with ethanol and deionized water for 5-6 times, and dried under vacuum at 70°C for 24 hours to obtain the intermediate product V6O 13 .

[0063] Step 2: Take the dried V6O 13 Place in a muffle furnace and heat in air at 3℃min -1 The product was obtained by heating to 200℃ and keeping the temperature for 2h and named V6O. 13 -200.

[0064] Example 2

[0065] The only difference from Example 1 is that in step 2, the calcination temperature is 300°C. The final product is named V6O 13 -300.

[0066] Example 3

[0067] The only difference from Example 1 is that in step 2, the calcination temperature is 500°C. The final product is named V6O 13 -500.

[0068] Effect verification

[0069] 1. Material structure analysis and morphology analysis

[0070] In order to study the crystal structure and chemical composition of the samples, the prepared samples were tested using X-ray diffraction analysis technology. Figure 1 The XRD spectrum shown in (a) shows that the diffraction peaks of the hydrothermal product are consistent with those of V6O 13 The standard diffraction peaks of V2O5 correspond to those of V6O5 (space group assigned to C2 / m(12)), indicating that in an acidic environment and a high-temperature aqueous solution with a small amount of ethylene glycol added, the valence of part of V in V2O5 is reduced and converted into V6O 13 Secondly, compared with V6O 13 (Intermediate product obtained in step 1 of the embodiment) and V6O 13 -200's XRD spectrum is at the 200 crystal plane, V6O 13There are certain defects, but after high temperature treatment at 200℃, the defects disappear, indicating that high temperature calcination improves the crystallinity of the 200 crystal plane, making V6O 13 Has a more ordered crystal structure. Compare again to V6O 13 -200 and V6O 13 -300's XRD spectrum, such as Figure 1 As shown in (b), V6O can be observed 13 The (110) crystal plane of -300 shows a shift in the forward Bragg reflection. According to the Bragg equation:

[0071] 2dsinθ=nλ

[0072] Where n is an integer multiple of the wavelength; d is the distance between parallel atomic planes; λ is the wavelength of the incident wave; and θ is the angle between the incident light and the crystal plane.

[0073] The results showed that V6O 13 The -200 sample has a larger lattice spacing at the 110 crystal plane. The large lattice spacing can increase the Zn 2+ Finally, when the calcination temperature reaches 500℃, the V6O 13 -500 XRD spectrum, after comparison with the diffraction peaks of commercial V2O5, is highly similar, indicating that the initial state of V6O 13 A phase transition occurs, generating V2O5.

[0074] The morphology and element distribution of the samples were characterized in detail by SEM, TEM and EDS-mapping. Figure 2 SEM of the samples shown in (a)-(d), Figure 2 (a)-(d) are TEM images of the sample, showing the initial state of V6O 13 With V6O 13 -200, V6O 13 -300, there is no significant change, all showing irregular nano-sheets. The advantage of the sheet structure is that it has a large contact area with the electrolyte, which is conducive to the electrochemical reaction. However, when the calcination temperature reaches 500℃, it can be observed that the morphology of the material changes significantly, the sheet structure disappears and becomes granular. The XRD spectrum shows that at 500℃, V6O 13 Converted to V2O5, during the high temperature calcination process, oxygen in the air atmosphere is inserted into V6O in the form of oxygen atoms 13 The element distribution was characterized as follows Figure 4 As shown, the element mapping results show that the V and O elements are evenly distributed in the structure.

[0075] XPS was used to characterize V6O 13and V6O 13 -200 valence state of the material, e.g. Figure 5 (a) shows V6O 13 and V6O 13 -200 V 2p spectrum, V6O 13 The characteristic peaks at 517.15 / 524.25 eV are attributed to V 5+ ; The characteristic peaks at 515.9 / 522.95 are attributed to V 4+ V6O 13 The characteristic peaks of -200 at 517.5 / 524.4 eV are attributed to V 5+ ; The characteristic peaks at 515.9 / 523.0 are attributed to V 4+ There is no obvious difference between the two, indicating that annealing does not lead to V6O 13 Phase transition. Calculation of fitting peak area, V6O 13 V 4+ / V 5+ =0.96 and V6O 13 -200 V 4+ / V 5+ =0.77, indicating that after annealing, part of V 4+ Oxidation to V 5+ , more V 5+ The presence of can cause the transfer of multiple electrons during the redox reaction, providing more specific capacity for the electrode. Figure 5 (b) shows the O1s spectrum, V6O 13 The characteristic peaks of lattice oxygen, oxygen vacancy and VO bond appear in the sample, while V6O 13 -200 only has the characteristic peaks of oxygen vacancies and VO bonds, and V6O is calculated based on the fitted peak area. 13 The oxygen vacancy ratio in the sample is O d =0.35; V6O 13 -200 Oxygen vacancies in the sample d =0.52, indicating that after annealing treatment, V6O 13 -200 produces more oxygen vacancies.

[0076] In order to directly prove whether there are oxygen vacancies, the present invention uses a more accurate detection technology, electron paramagnetic resonance spectroscopy, to perform oxygen vacancy testing. Figure 6 V6O 13 With V6O 13 -200 sample EPR curve. As can be seen from the figure, due to the local charge imbalance inside the crystal, unpaired electrons interact with each other and generate signals during the detection process. 13 With V6O 13The paramagnetic symmetry center of the -200 sample is g = 2.0039, indicating that the 13 With V6O 13 -200 samples were all detected with oxygen vacancies, V6O 13 -200 produces a significantly higher signal than V6O 13 This indicates that the oxygen vacancy content is relatively high.

[0077] Figure 7 V6O shown in (a) 13 / V6O 13 -200 N2 adsorption-desorption isotherm diagram, the test result is V6O 13 and V6O 13 The specific surface areas of -200 are 13.86m 2 g -1 、14.59m 2 g -1 . Figure 7 (b) shows the pore size distribution. The pore size distribution of both is mainly mesopores. 13 -200 has a slightly larger specific surface area, and the presence of a mesoporous structure can enhance the Zn 2+ transmission dynamics.

[0078] Figure 8 (a)-(b) shows V6O 13 / V6O 13 -200 sample thermogravimetric curve, from room temperature to 100℃, V6O 13 / V6O 13 -200℃, the weight loss was 4.4% and 2% respectively. This process is the evaporation of free water in the material. The mass reduction in the second stage at 100℃-450℃ is due to the elimination of crystal water in the material structure. The third stage is a sudden change at 400-800℃, and a process of increasing the material mass appears. According to the literature research, this process V6O 13 Phase change occurs and oxidation reaction occurs at high temperature, turning into V2O5. 13 / V6O 13 The -200 sample reaches the maximum loss of 14.7% and 10.3% at 400℃, indicating that V6O 13 -200 has strong thermal stability.

[0079] 2. Battery performance testing and analysis

[0080] Aqueous zinc-ion batteries were assembled using a Swagelok battery test mold, and the electrochemical performance of the synthesized samples was tested at room temperature.

[0081] First, electrodes were prepared for different synthesized samples and batteries were assembled for testing. Figure 9 (a) shows different electrodes at 0.5Ag -1 Cyclic tests were conducted at current density. First, V6O without annealing was synthesized hydrothermally. 13 ( Figure 9 The highest specific capacity in (b) is only 304 mAh g -1 The specific capacity after 200 cycles is 284 mAh g -1 , the capacity retention rate is 93%. Obviously, V6O 13 The electrochemical performance of the -200 electrode is particularly outstanding, with a maximum specific capacity of 407 mAh g during cycling. -1 , it can still provide 388mAh g after 200 cycles -1 The specific capacity ( Figure 9 In (c), the capacity retention rate reaches 95.3%. 13 The -300 electrode reached 528 mAh g in the first discharge. -1 The reason for this phenomenon is that as the annealing temperature increases, V6O 13 More V 4+ Oxidation occurs to V 5+ , which allows the electrode to release more energy, but then enters the capacity decay process. XRD shows that V6O 13 -300 110 crystal plane 2θ diffraction angle compared to V6O 13 -200 shows a positive movement, indicating that V6O 13 -300 has a reduced lattice spacing, making Zn 2+ The insertion / extraction of the battery is subject to great resistance, and the specific capacity is only 213 mAh g after 200 cycles. -1 , the capacity retention rate is only 40%. Secondly, V6O 13 During the cycling process, the test curve of the -500 electrode is significantly different from that of other electrodes. The initial cycle specific capacity is extremely low, and the capacity continues to increase as the test progresses.

[0082] Subsequently, the rate performance of different electrodes was tested, and the results were as follows: Figure 9 As shown in (d), V6O 13 -200 electrode exhibits excellent electrochemical performance at all current densities, ranging from 0.2 to 5Ag -1 The specific capacities obtained at the current densities were 465, 439, 416, 387, and 342 mAh g -1 . And V6O 13 Electrode in the range of 0.2 to 5Ag -1 The only specific capacities available at current densities are 364, 346, 330, 310, and 273 mAh g -1At the same time, you can Figure 9 In (e)-(f), it is clearly observed that with the increase of current density, V6O 13 With V6O 13 -200 Change in electrode specific capacity.

[0083] At the same time, XRD confirmed that V6O after annealing at 500℃ 13 Converted to V2O5, through V6O 13 -500 electrode was tested for rate performance, and the test curve obtained was very similar to the test results of commercial V2O5, and the test results were consistent with the XRD test results. The reason for the extremely low specific capacity and the poor cycle stability is that unregulated V2O5 has multiple problems as a positive electrode material for aqueous zinc ion batteries. For example, the low specific surface area leads to a large internal resistance of the material, which makes Zn 2+ The diffusion of Zn is subject to greater resistance. As the number of cycles increases, the specific capacity continues to rise, which may be due to the 2+ Continuously embedded in the V2O5 lattice, the interlayer spacing of the V2O5 lattice is increased in situ, and the electrode is gradually activated, providing Zn 2+ The embedding continuously creates additional active sites, causing the capacity to continuously increase with the number of tests.

[0084] To evaluate V6O 13 -200 electrode commercial potential, and conducted high current density long cycle performance tests to prove the V6O 13 -200 cycle stability of the electrode. Figure 10 V6O shown 13 -200 electrode at 2Ag -1 The optimal specific capacity is 360 mAh g -1 , after 1000 cycles, it still has 332mAh g -1 , the capacity retention rate is 92%.

[0085] At the same time, 5Ag was also carried out -1 Cyclic testing, such as Figure 11 V6O shown 13 With V6O 13 -200 electrode cycle test, V6O 13 -200 showed the best specific capacity of 340 mAh g -1 , after 4000 cycles, it still has 256mAh g -1 The capacity retention rate is 75%. 13 The battery short-circuited after only 260 cycles, and the results of multiple tests were similar.

[0086] 3. Reaction kinetics analysis

[0087] To further explore V6O 13 With V6O 13 -200 electrochemical reaction kinetics and zinc storage behavior. Cyclic voltammetry tests were carried out on the two electrodes, such as Figure 12 As shown in (a)-(b), with the increase of scan rate, the oxidation / reduction peaks of the two electrodes shift due to the electrochemical polarization effect, and the shapes of the overall curves are similar, indicating that the oxidation / reduction reactions of the electrodes are reversible.

[0088] i=av b

[0089] log(i)=log(a)+blog(v)

[0090] From the above electrochemical kinetics, we can see from the formula that i is the current (mA), v is the scan rate, a and b are variable parameters, and b is determined by fitting the linear function of log(i) and log(v). When b = 1.0, it indicates that the electrochemical process of the electrode is capacitance controlled. When b is between 0.5-1.0, it indicates that both diffusion control and pseudocapacitive behavior participate in the electrochemical reaction, and pseudocapacitance plays a dominant role. Figure 12 From (c) and (d), we can see that V6O 13 The fitting b values ​​are 0.89, 1.00, 0.88, and 0.93 respectively; V6O 13 -200 fitting b values ​​are 0.85, 1.00, 0.90, and 0.90 respectively. This shows that the pseudocapacitance is controlled in V6O 13 -200 battery plays a major role in the capacitance contribution.

[0091] The contributions of capacitive and diffusion-controlled processes to the electrode capacitance are quantified using the above formula, where k1 and k2 are the coefficients of diffusion-controlled and capacitive processes, respectively. 13 With V6O 13 -200 pseudocapacitance contribution ratio, such as Figure 12 As shown in (e) and (f), they are 86% and 87% respectively. At the same time, as the scan rate increases, the contribution of charge diffusion also increases, as shown in Figure 13 V6O shown in (a) and (b) 13 With V6O 13 Pseudocapacitance contribution of the -200 electrode at different scan rates.

[0092] In addition, to further analyze the kinetic behavior, V6O 13 With V6O 13 The full battery assembled with -200 electrodes was subjected to EIS impedance test. Figure 14 As shown in (a), in the low frequency part V6O 13 With V6O 13-200 electrode charge transfer resistance (R ct ) are 468Ω and 264Ω respectively, V6O 13 The charge transfer resistance of the -200 electrode is small because the annealed V6O 13 The lattice spacing inside the -200 sample is expanded, and the electron transmission rate is accelerated.

[0093] At the same time, for the high frequency part of the Warburg impedance, Z' and ω 1 / 2 The slope of the fitting line represents the ion diffusion resistivity. Figure 14 V6O shown in (b) 13 The slope of -200 electrode is 52, which is significantly smaller than that of V6O 13 86 of the electrode, indicating V6O 13 -200 has faster ion transport kinetics and is more favorable for Zn 2+ diffusion, which makes V6O 13 -200 samples showed excellent electrochemical performance.

[0094] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A type of V6O 13 The method for preparing a nanomaterial is characterized in that: The following steps are involved: The intermediate product was prepared by hydrothermal method using V2O5 as vanadium source; The intermediate product is annealed to obtain the V6O 13 Nanomaterials.

2. A V6O according to claim 1 13 The method for preparing a nanomaterial is characterized in that: The specific steps of the hydrothermal method are: V2O5, polyvinyl pyrrolidone and ethylene glycol are added to deionized water and stirred evenly, and then hydrochloric acid is added dropwise thereto and stirred evenly again, and then a hydrothermal reaction is carried out in a reactor, and then centrifuged, washed and dried in sequence to obtain an intermediate product.

3. A V6O according to claim 2 13 The method for preparing a nanomaterial is characterized in that: The usage ratio of V2O5, polyvinyl pyrrolidone, ethylene glycol, deionized water and hydrochloric acid is: 3mmol: 200mg: 1mL: 60ml: 1ml.

4. V6O according to claim 2 13 The method for preparing a nanomaterial is characterized in that: The conditions of the hydrothermal reaction are: keeping warm at 180° C. for 12 h.

5. A V6O according to claim 2 13 The method for preparing a nanomaterial is characterized in that: The centrifugal conditions are: at 5000 r min -1 Centrifuge for 3 minutes; and / or, The drying conditions are: vacuum drying at 70° C. for 24 h.

6. The V6O according to claim 1 13 The method for preparing a nanomaterial is characterized in that: The annealing conditions are: 3°C min in air atmosphere -1 Heat to 200-400°C and keep warm for 2 hours.

7. The V6O according to claim 6 13 The method for preparing a nanomaterial is characterized in that: The annealing conditions are: 3°C min in air atmosphere -1 Heat to 200°C and keep warm for 2h.

8. A V6O 13 Nanomaterials, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. V6O as claimed in claim 8 13 Application of nanomaterials as aqueous zinc ion cathode materials.

10. An aqueous zinc ion battery, characterized in that: The positive electrode is V6O as claimed in claim 8 13 Nanomaterials.

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