A dual-ion regulated vanadium dioxide nanowire electrode material, a preparation method and application thereof

Abstract

This invention relates to the field of electrode materials technology, and particularly to a method for preparing a dual-ion-controlled vanadium dioxide nanowire electrode material. The steps are as follows: S1, dissolve a vanadium source in oxalic acid solution to form a first solution, and stir the first solution in a water bath at 80℃±10℃ for 1-2 hours until the overall color of the first solution changes from orange to dark blue; S2, simultaneously add an aluminum source solution and a zirconium source solution dropwise to the dark blue first solution, and stir at room temperature for 10 minutes to obtain a second solution; S3, transfer the second solution obtained in step S2 to a high-pressure reactor, heat it uniformly to 140℃-220℃, maintain the temperature for 1-6 hours, and allow it to cool naturally to room temperature after the reaction. Wash the reaction product with ethanol and deionized water, and then vacuum dry it at 80℃ for 24 hours to obtain the dual-ion-controlled vanadium dioxide nanowire electrode material. The dual-ion-controlled vanadium dioxide nanowire electrode material provided by this invention has both specific capacity and cycle stability, and has good application value.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, and in particular to a dual-ion controlled vanadium dioxide nanowire electrode material, its preparation method, and its application. Background Technology

[0002] With increasing fossil fuel consumption and escalating environmental challenges, aqueous zinc-ion batteries (ZIBs) have emerged as a promising and sustainable energy storage solution, effectively meeting the urgent need for reliable and environmentally friendly energy. Zinc-ion batteries leverage the inherent advantages of zinc metal, such as high theoretical capacity and compatibility with water, paving a viable path for energy storage technology. The use of aqueous electrolytes further enhances their appeal due to their cost-effectiveness, safety, and high ionic conductivity. However, issues such as dissolution and structural instability in zinc-ion battery cathode materials hinder their practical application. Researchers are actively exploring novel cathode materials to optimize battery performance, including higher energy density, power density, and longer cycle life.

[0003] Vanadium dioxide (VO2(B)) in phase B stands out as a prominent member of the vanadium oxide family. It has attracted considerable attention as a promising electrode material in zinc-ion batteries, mainly due to its complex porous tunnel-like framework structure, which can mitigate the volume expansion caused by zinc ion insertion / extraction.

[0004] However, vanadium dioxide electrode materials face dual constraints in aqueous zinc-ion batteries: stability and ionic conductivity. On the one hand, their crystal structure in Zn... 2+ Irreversible phase transitions, lattice distortions, and vanadium dissolution still occur during repeated insertion / extraction processes, leading to a decrease in cycle stability. Furthermore, vanadium dioxide itself has low electronic conductivity, while Zn... 2+ The high diffusion barrier and slow ion transport kinetics in tunnel structures exacerbate polarization at high magnification and further deteriorate structural integrity due to local stress concentration, severely limiting the actual electrochemical performance of vanadium dioxide electrode materials.

[0005] Therefore, how to modify vanadium dioxide electrode materials to improve their electrochemical performance has become a research hotspot. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a dual-ion regulated vanadium dioxide nanowire electrode material, its preparation method and application, thereby solving the problems of insufficient stability and insufficient electrochemical performance of existing vanadium dioxide electrode materials.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for preparing a dual-ion controlled vanadium dioxide nanowire electrode material, comprising the following steps: S1. Dissolve the vanadium source in oxalic acid solution to form the first solution. Stir the first solution in a water bath at 80℃±10℃ at a speed of 300~800r / min for 1~2h, so that the overall color of the first solution changes from orange to dark blue. S2. The aluminum source solution and the zirconium source solution are simultaneously added dropwise to the dark blue first solution, and stirred at 500 r / min for 10 min at room temperature to obtain the second solution. S3. Transfer the second solution obtained in step S2 to a high-pressure reactor, heat it at a constant rate to 140℃~220℃ and maintain the temperature for 1~6h. After the reaction is completed, cool it naturally to room temperature. Wash the reaction product with ethanol and deionized water and then vacuum dry it at 80℃ for 24h to obtain the dual-ion regulated vanadium dioxide nanowire electrode material.

[0008] In one embodiment, the vanadium source includes any one or a combination of vanadium pentoxide, ammonium vanadate, and vanadium oxysulfate; the aluminum source includes any one or a combination of aluminum nitrate, aluminum sulfate, and aluminum chloride; and the zirconium source includes any one or a combination of zirconium nitrate, zirconium oxychloride, and zirconium oxynitrate. Preferably, the vanadium source is vanadium pentoxide, the aluminum source is aluminum nitrate, and the zirconium source is zirconium nitrate.

[0009] In one embodiment, in step S1, the molar ratio of vanadium to oxalic acid in the vanadium source is 20:(15-30). Preferably, the molar ratio of vanadium to oxalic acid in the vanadium source is 20:20.

[0010] In one embodiment, in step S2, the molar ratio of vanadium, aluminum, and zirconium in the vanadium source, aluminum source, and zirconium source is 20:(0.2-1):(0.5-2). Preferably, the molar ratio of vanadium, aluminum, and zirconium is 20:0.5:1.

[0011] In one embodiment, the atomic molar ratio of aluminum to vanadium in the dual-ion regulated vanadium dioxide nanowire electrode material obtained in step S3 is 1 at% to 5 at%, and the atomic molar ratio of zirconium to vanadium is 2.5 at% to 10 at%. Preferably, the atomic molar ratio of aluminum to vanadium is 2.5 ± 0.5 at%, and the atomic molar ratio of zirconium to vanadium is 5 ± 1 at%.

[0012] In one embodiment, in step S3, the heating rate of the high-pressure reactor is 3.5℃~7℃ / min.

[0013] In one embodiment, in step S3, the second solution is heated at a constant rate to 160°C–200°C in a high-pressure reactor and then maintained at a stable temperature for 2.5–4 hours. Preferably, the second solution is heated at a constant rate to 180°C ± 10°C in a high-pressure reactor and then maintained at a stable temperature for 2.5–4 hours.

[0014] The present invention also provides a dual-ion controlled vanadium dioxide nanowire electrode material prepared by any of the preparation methods described above.

[0015] In one embodiment, the whiskers are in the form of nanowires with a length of 350–600 nm.

[0016] This invention also provides an application of a dual-ion regulated vanadium dioxide nanowire electrode material in a zinc-ion battery.

[0017] In one embodiment, the dual-ion controlled vanadium dioxide nanowire electrode material is used as the positive electrode of a zinc-ion battery, and the preparation steps are as follows: The prepared dual-ion controlled vanadium dioxide nanowire electrode material, activated carbon and polyvinylidene fluoride were added to a grinding device at a mass ratio of 7:2:1 and ground and mixed until viscous to obtain an active slurry. The active slurry is coated onto carbon paper and dried at 80°C for 12 hours to form an active material layer on the carbon paper, thus obtaining the positive electrode sheet. In one embodiment, a zinc-ion battery using a positive electrode retains ≥90% of its capacity after 3000 cycles at a current density of 5 A / g.

[0018] In one embodiment, the assembly steps of the zinc-ion battery are as follows: Zinc foil is used as a negative electrode after the oxide layer on the surface is sanded off with sandpaper. In an air environment, zinc foil negative electrode, glass fiber separator, Zn(CF3SO3)2 electrolyte, positive electrode and CR2032 battery case are assembled sequentially to obtain a zinc-ion battery.

[0019] The beneficial effects of this invention are as follows: 1. Ion doping broadens the diffusion channels and improves the conductivity of vanadium-based materials, thereby increasing the electronic conductivity of the materials.

[0020] 2. The dual-ion controlled vanadium dioxide nanowire electrode material provided by this invention adjusts and improves the crystal morphology of vanadium dioxide through co-doping with Zr and Al. After Al doping, the whiskers of VO2(B) exhibit a vertical growth trend, while after Zr doping, the whiskers exhibit a horizontal growth trend. After co-doping with the two in a certain proportion, the morphology of VO2(B) is controlled, making the whiskers full nanowires with a whisker length maintained at around 500 nm. This morphology not only reduces contact with the electrolyte and reduces the generation of side reactions, but also shortens the ion diffusion path, thereby ultimately improving the overall performance of the battery.

[0021] 3. The preparation method of the dual-ion regulated vanadium dioxide nanowire electrode material provided by the present invention uses Zr doping to improve the specific capacity of the composite material and Al doping to improve the cycle stability of the composite material. At the same time, through the synergistic effect of the two doping elements, the specific capacity and cycle stability of the composite material are controlled and improved simultaneously.

[0022] 4. The preparation method of the dual-ion regulated vanadium dioxide nanowire electrode material provided by the present invention has a simple and stable synthesis process, low equipment and production costs, and is easy to industrialize, thus having good promotional value.

[0023] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects of the invention and other beneficial effects may be realized and obtained by means of the structures and / or components pointed out in the description and claims. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating an embodiment of the present invention; Figure 2 These are the XRD patterns of Embodiment 1 and Comparative Example 1 of the present invention; Figure 3 These are scanning electron microscope images of Embodiment 1 and Comparative Examples 1 to 3 of the present invention; Figure 4 This is a comparison chart of the rate performance of Embodiment 1 and Comparative Example 1 of the present invention; Figure 5 This is a comparison chart of the cycle performance of Embodiment 1 and Comparative Example 1 of the present invention; Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0026] Example 1 S1. Dissolve 10 mmol of vanadium pentoxide in 100 ml of 0.2 mol / L oxalic acid solution to form the first solution. Stir the first solution in an 80℃ water bath at a speed of 500 r / min for 1 h until the first solution turns dark blue. S2. Then, 10 ml of 0.05 mol / L aluminum nitrate solution and 10 ml of 0.1 mol / L zirconium nitrate solution were added dropwise to the dark blue first solution. The mixture was stirred at 500 r / min for 10 min at room temperature to obtain the second solution. S3. The second solution obtained in step S2 is transferred to a reaction vessel and heated from room temperature to 180°C at a heating rate of 5°C / min. The mixture is then subjected to hydrothermal reaction at 180°C for 3 hours. After the reaction is completed, the mixture is cooled to room temperature. The reactants are washed with ethanol and deionized water and then vacuum dried at 80°C for 24 hours to obtain the dual-ion regulated vanadium dioxide nanowire electrode material.

[0027] Comparative Example 1 S1. Dissolve 10 mmol of vanadium pentoxide in 100 ml of 0.2 mol / L oxalic acid solution to form the first solution. Stir the first solution in an 80℃ water bath at a speed of 500 r / min for 1 h until the first solution turns dark blue. S2. The first solution is transferred to a reaction vessel and heated from room temperature to 180°C at a heating rate of 5°C / min. The mixture is then subjected to hydrothermal reaction at 180°C for 3 hours. After the reaction is completed, the mixture is cooled to room temperature. The reactants are washed with ethanol and deionized water and then vacuum dried at 80°C for 24 hours to obtain vanadium dioxide electrode material.

[0028] Comparative Example 2 S1. Dissolve 10 mmol of vanadium pentoxide in 100 ml of 0.2 mol / L oxalic acid solution to form the first solution. Stir the first solution in an 80℃ water bath at a speed of 500 r / min for 1 h until the first solution turns dark blue. S2. Then, 10 ml of 0.05 mol / L aluminum nitrate solution was added dropwise to the dark blue first solution, and stirred at 500 r / min for 10 min at room temperature to obtain the second solution. S3. The second solution obtained in step S2 is transferred to a reaction vessel and heated from room temperature to 180°C at a heating rate of 5°C / min. The mixture is then subjected to hydrothermal reaction at 180°C for 3 hours. After the reaction is completed, the mixture is cooled to room temperature. The reactants are washed with ethanol and deionized water and then vacuum dried at 80°C for 24 hours to obtain aluminum ion-controlled vanadium dioxide electrode material.

[0029] Comparative Example 3 S1. Dissolve 10 mmol of vanadium pentoxide in 100 ml of 0.2 mol / L oxalic acid solution to form the first solution. Stir the first solution in an 80℃ water bath at a speed of 500 r / min for 1 h until the first solution turns dark blue. S2. Then, 10 ml of 0.1 mol / L zirconium nitrate solution was added dropwise to the dark blue first solution, and stirred at 500 r / min for 10 min at room temperature to obtain the second solution. S3. The second solution obtained in step S2 is transferred to a reaction vessel and heated from room temperature to 180°C at a heating rate of 5°C / min. The mixture is then subjected to hydrothermal reaction at 180°C for 3 hours. After the reaction is completed, the mixture is cooled to room temperature. The reactants are washed with ethanol and deionized water and then vacuum dried at 80°C for 24 hours to obtain zirconium ion-controlled vanadium dioxide electrode material.

[0030] Comparative Example 4 S1. Dissolve 10 mmol of vanadium pentoxide in 100 ml of 0.2 mol / L oxalic acid solution to form the first solution. Stir the first solution in an 80℃ water bath at a speed of 500 r / min for 1 h until the first solution turns dark blue. S2. Then, 10 ml of 0.05 mol / L aluminum nitrate solution and 10 ml of 0.1 mol / L zirconium nitrate solution were added dropwise to the dark blue first solution. The mixture was stirred at 500 r / min for 10 min at room temperature to obtain the second solution. S3. The second solution obtained in step S2 is transferred to a reaction vessel and stirred at room temperature for 3 hours. The reactants are washed with ethanol and deionized water and then dried under vacuum at 80°C for 24 hours to obtain vanadium dioxide electrode material.

[0031] Comparative Example 5 S1. Dissolve 10 mmol of vanadium pentoxide in 100 ml of 0.2 mol / L oxalic acid solution to form the first solution. Stir the first solution in an 80℃ water bath at a speed of 500 r / min for 1 h until the first solution turns dark blue. S2. Then, 10 ml of 0.05 mol / L aluminum nitrate solution and 10 ml of 0.1 mol / L zirconium nitrate solution were added dropwise to the dark blue first solution. The mixture was stirred at 500 r / min for 10 min at room temperature to obtain the second solution. S3. The second solution obtained in step S2 is transferred to a reaction vessel and heated from room temperature to 210°C at a heating rate of 5°C / min. The mixture is then subjected to hydrothermal reaction at 180°C for 3 hours. After the reaction is completed, the mixture is cooled to room temperature. The reactants are washed with ethanol and deionized water and then vacuum dried at 80°C for 24 hours to obtain the dual-ion regulated vanadium dioxide nanowire electrode material.

[0032] Comparative Example 6 S1. Dissolve 10 mmol of vanadium pentoxide in 100 ml of 0.2 mol / L oxalic acid solution to form the first solution. Stir the first solution in an 80℃ water bath at a speed of 500 r / min for 1 h until the first solution turns dark blue. S2. Then, 10 ml of 0.05 mol / L aluminum nitrate solution and 10 ml of 0.1 mol / L zirconium nitrate solution were added dropwise to the dark blue first solution. The mixture was stirred at 500 r / min for 10 min at room temperature to obtain the second solution. S3. The second solution obtained in step S2 is transferred to a reaction vessel and heated from room temperature to 180°C at a heating rate of 5°C / min. The mixture is then subjected to hydrothermal reaction at 150°C for 6 hours. After the reaction is completed, the mixture is cooled to room temperature. The reactants are washed with ethanol and deionized water and then vacuum dried at 80°C for 24 hours to obtain the dual-ion regulated vanadium dioxide nanowire electrode material.

[0033] It should be noted that the specific parameters or some commonly used reagents in the above embodiments are specific or preferred embodiments under the concept of the present invention, and not limitations thereof; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

[0034] In addition, unless otherwise specified, the raw materials used may be commercially available products in the field, or prepared by conventional methods in the field.

[0035] XRD analysis was performed on Example 1 and Comparative Example 1, and the specific results are as follows: Figure 2 As shown. Figure 2 It is noted that the crystal structure of the materials obtained in Example 1 and Comparative Example 1 is VO2(B), and the diffraction peaks of the crystal in Example 1 were weakened after Zr and Al doping.

[0036] The results of Example 1 and Comparative Examples 1-3 were obtained by scanning electron microscopy. Figure 3 As shown. By Figure 3 From this, it can be seen that, in Comparative Example 1, the whisker morphology of VO2(B) in the material is nanorod-like, with a whisker length of approximately 50–300 nm. Figure 3 As can be seen from c, the whiskers of Comparative Example 2, which only underwent Al doping, exhibit longitudinal growth, forming slender nanowires with a length of approximately 2 μm. The excessively long whiskers result in a high aspect ratio, making them prone to bending and breakage during prolonged use, thus affecting stability. Figure 3 As can be seen from d, the whiskers of Comparative Example 3, which only underwent Zr doping, formed granular particles with a diameter of less than 100 nm. Figure 3 b shows that the whiskers of Example 1, which uses Zr and Al co-doping, are saturated nanowires with uniform diameter, orderly arrangement, and an average whisker length of about 500 nm.

[0037] The samples from Example 1 and Comparative Examples 1 to 6 were prepared as positive electrode sheets and then assembled into zinc-ion batteries.

[0038] The specific steps are as follows: The prepared dual-ion controlled vanadium dioxide nanowire electrode material, activated carbon and polyvinylidene fluoride are added to a grinding device in a mass ratio of 7:2:1 and ground and mixed until viscous to obtain an active slurry. The active slurry is coated onto carbon paper and dried at 80°C for 12 hours to form an active material layer on the carbon paper, thus obtaining the positive electrode sheet. Zinc foil is used as a negative electrode after the oxide layer on the surface is sanded off with sandpaper. In an air environment, zinc foil negative electrode, glass fiber separator, Zn(CF3SO3)2 electrolyte, positive electrode and CR2032 battery case are assembled sequentially to obtain a zinc-ion battery.

[0039] The obtained zinc-ion batteries were subjected to discharge capacity testing and 3000-cycle testing. The test results are shown in Table 1.

[0040] Table 1 Test Results

[0041] As shown in Table 1, the electrochemical performance of the material used in Example 1 as the cathode material for an aqueous zinc-ion battery is significantly better than that of Comparative Examples 1-6. Comparative Example 1, being undoped, lacks the heterostructure ion pillar effect, leading to easy lattice collapse and severe vanadium dissolution during cycling, resulting in a capacity retention rate of only 31.1%. Comparative Examples 2 and 3, due to single Al or Zr doping respectively, suffer from an imbalance in crystal morphology control. The former exhibits excessive whisker growth, which easily leads to mechanical fracture risk and restricts ion diffusion, while the latter inhibits excessive nanoparticle formation, exacerbating surface side reactions and agglomeration, making it difficult to balance capacity and stability. Comparative Example 4 lacks a hydrothermal crystallization step, resulting in poor crystallinity of the product and the inability of doped ions to effectively enter the lattice, leading to low electrochemical activity. Comparative Example 5 suffers from high-temperature impurity phase formation or whisker fracture due to excessively high hydrothermal temperature, while Comparative Example 6 suffers from insufficient low-temperature crystallization kinetics due to insufficient hydrothermal temperature, resulting in the final materials failing to meet the required electrochemical performance.

[0042] The rate performance comparison test and the 1000-cycle stability test were continued for Example 1 and Comparative Example 1. The test results are as follows: Figure 4 and Figure 5 As shown.

[0043] Depend on Figure 4 It can be seen that, within a voltage window of 0.2–1.4 V, Example 1 achieves a current density of 10 A g. -1 It still has 281mAh g -1 The reversible capacity. (By...) Figure 5 It can be seen that the zinc-ion battery prepared in Example 1 retains a reversible capacity of 265 mAh g after 1000 cycles. -1 With a capacity retention rate of 91.6%, it has excellent application value.

[0044] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0045] Although terms such as vanadium source and aluminum source are used frequently in this document, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any kind of additional limitation would contradict the spirit of the invention. Terms such as "first," "second," etc. (if present) in the specification and claims of the embodiments of the invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a dual-ion-controlled vanadium dioxide nanowire electrode material, characterized in that, The steps are as follows: S1. Dissolve the vanadium source in oxalic acid solution to form a first solution. Stir the first solution in a water bath at 80℃±10℃ at a speed of 300~800r / min for 1~2h, so that the overall color of the first solution changes from orange to dark blue. S2. The aluminum source solution and the zirconium source solution are simultaneously added dropwise to the dark blue first solution, and stirred at 500 r / min for 10 min at room temperature to obtain the second solution. S3. Transfer the second solution obtained in step S2 to a high-pressure reactor, heat it at a constant rate to 140℃~220℃ and maintain the temperature for 1~6h. After the reaction is completed, cool it naturally to room temperature. Wash the reaction product with ethanol and deionized water and then vacuum dry it at 80℃ for 24h to obtain the dual-ion regulated vanadium dioxide nanowire electrode material.

2. The preparation method according to claim 1, characterized in that: The vanadium source includes any one or a combination of vanadium pentoxide, ammonium vanadate, and vanadium oxysulfate; the aluminum source includes any one or a combination of aluminum nitrate, aluminum sulfate, and aluminum chloride; and the zirconium source includes any one or a combination of zirconium nitrate, zirconium oxychloride, and zirconium oxynitrate.

3. The preparation method according to claim 2, characterized in that: In step S1, the molar ratio of vanadium to oxalic acid in the vanadium source is 20:(15-30).

4. The preparation method according to claim 2, characterized in that: In step S2, the molar ratio of vanadium, aluminum and zirconium in the vanadium source, aluminum source and zirconium source is 20:(0.2~1):(0.5~2).

5. The preparation method according to claim 1, characterized in that: In the dual-ion regulated vanadium dioxide nanowire electrode material prepared in step S3, the atomic molar ratio of aluminum to vanadium is 1 at% to 5 at%, and the atomic molar ratio of zirconium to vanadium is 2.5 at% to 10 at%.

6. The preparation method according to claim 1, characterized in that: In step S3, the heating rate of the high-pressure reactor is 3.5℃~7℃ / min.

7. The preparation method according to claim 1, characterized in that: In step S3, the second solution is heated at a constant rate to 160℃~200℃ in a high-pressure reactor and then the temperature is maintained for 2.5~4h.

8. A dual-ion controlled vanadium dioxide nanowire electrode material prepared by the preparation method according to any one of claims 1 to 7.

9. The dual-ion controlled vanadium dioxide nanowire electrode material according to claim 8, characterized in that: The whiskers are in the form of nanowires, with a length of 350–600 nm.

10. Application of a dual-ion regulated vanadium dioxide nanowire electrode material in zinc-ion batteries.

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