A KVOH nanomaterial, its preparation method, and an aqueous zinc-ion battery

Abstract

This application provides a KVOH nanomaterial, its preparation method, and an aqueous zinc-ion battery to address the technical problem of low performance of vanadium pentoxide cathode materials in the prior art. The KVOH nanomaterial provided in this application is obtained by a solvothermal reaction in an aqueous ethylene glycol solution. The introduction of potassium ions in the reaction expands the ion transport channels between the electrode material layers, improving the cycle performance of the battery. At the same time, the introduction of tetravalent vanadium also increases the specific capacity of the battery, thereby solving the technical problem of low performance of vanadium pentoxide cathode materials in the prior art.

Description

Technical Field

[0001] This application belongs to the field of electrode material technology, and particularly relates to a KVOH nanomaterial, its preparation method, and an aqueous zinc-ion battery. Background Technology

[0002] In addition to conventional lithium-ion and sodium-ion batteries, other ion batteries have also attracted attention. For example, rechargeable aqueous zinc-ion batteries are considered to have great development prospects in the field of large-scale energy storage due to their advantages such as high safety, high specific capacity, low cost and easy packaging.

[0003] Similar to lithium-ion and sodium-ion batteries, rechargeable aqueous zinc-ion batteries mainly consist of a positive electrode, a negative electrode, an electrolyte, and a separator. Vanadium pentoxide (VPO) possesses an open framework structure suitable for zinc ion insertion and extraction, making it a highly promising aqueous zinc-ion cathode material. However, VPO suffers from low intrinsic conductivity and insufficient crystal structure stability. Furthermore, the strong electrostatic interaction between zinc ions and VPO causes the layered structure of VPO to collapse during charging and discharging due to frequent zinc ion insertion and extraction, leading to capacity decay and cycle performance degradation. This significantly limits its practical application in aqueous zinc-ion batteries. Therefore, it is necessary to improve the performance of VPO cathode materials. Summary of the Invention

[0004] In view of this, this application provides a KVOH nanomaterial, a preparation method thereof, and an aqueous zinc-ion battery to solve the technical problem of low performance of vanadium pentoxide cathode materials in the prior art.

[0005] The first aspect of this application provides a KVOH nanomaterial, the chemical composition of which is: K 0.48 V2O5·nH2O, 0≤n≤2.

[0006] Preferably, the morphology of the KVOH nanomaterial is nanoribbons.

[0007] Preferably, the KVOH nanomaterial has a width of 30-60 nm and a length of 100-500 nm.

[0008] The second aspect of this application provides a method for preparing KVOH nanomaterials, which can prepare the KVOH nanomaterials described in the first aspect. The preparation method includes the following steps:

[0009] Step S1: Dissolve vanadium pentoxide and potassium ion compounds in an aqueous ethylene glycol solution to obtain a KVOH nanomaterial precursor solution;

[0010] Step S2: The KVOH nanomaterial precursor solution is subjected to a solvothermal reaction to obtain KVOH nanomaterials.

[0011] Preferably, in step S1, the volume ratio of ethylene glycol to deionized water in the ethylene glycol aqueous solution is 1:60~80.

[0012] Preferably, in step S1, the potassium ion compound is selected from potassium hydroxide.

[0013] Preferably, in step S1, the molar ratio of vanadium pentoxide to potassium ion compound is 1:0.1~1.

[0014] Preferably, in step S2, the temperature of the solvothermal reaction is 180~220℃ and the time is 8~30h.

[0015] Preferably, after step S2, there is also step S3 and a post-processing step;

[0016] The post-processing steps include: centrifugation, washing, and drying in sequence.

[0017] A third aspect of this application provides an aqueous zinc-ion battery, including a positive electrode, a negative electrode, a separator, and an electrolyte;

[0018] The cathode material is selected from the KVOH nanomaterials described in the first aspect.

[0019] Preferably, the positive electrode comprises the KVOH nanomaterial, conductive material, binder, and current collector described in the first aspect; the KVOH nanomaterial, conductive material, and binder are mixed and loaded onto the surface of the current collector;

[0020] The negative electrode is selected from zinc foil;

[0021] The diaphragm is selected from glass fiber filter paper;

[0022] The electrolyte is selected from an aqueous solution of zinc trifluoromethanesulfonate.

[0023] The fourth aspect of this application provides the application of KVOH nanomaterials in the fields of large-scale electrochemical energy storage batteries, photodetectors, field-effect transistors, or thermal / optical switches.

[0024] In summary, this application provides a KVOH nanomaterial, its preparation method, and an aqueous zinc-ion battery. The chemical composition of the KVOH nanomaterial provided in this application is K... 0.48V2O5·nH2O is obtained by a solvothermal reaction of vanadium pentoxide and potassium ion compounds dissolved in an aqueous ethylene glycol solution. During the solvothermal reaction, metal cations are introduced into the interlayer of vanadium pentoxide as a support, expanding the ion transport channels between the layers. This effectively suppresses the structural distortion of the cathode material caused by zinc ion insertion-extraction, improves the stability of the layered structure, and enhances the cycle stability of the battery. At the same time, ethylene glycol in the aqueous ethylene glycol solution has a certain reducing property, thereby regulating the content of tetravalent vanadium in the KVOH nanomaterial, improving the specific capacity of the battery. Furthermore, this application prepares KVOH nanomaterials based on the spontaneous pre-insertion reaction of metal cations under solvothermal conditions. Compared with conventional hydrolysis methods, it has the characteristics of mild reaction, simple and easy process, and high yield, thus solving the technical problem of low performance of vanadium pentoxide cathode materials in the prior art. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 The XRD pattern of the KVOH nanomaterial provided in Example 1 of this application;

[0027] Figure 2 This is a SEM image of the KVOH nanomaterial provided in Example 1 of this application;

[0028] Figure 3 This is an X-ray photoelectron spectroscopy analysis diagram of the KVOH nanomaterial provided in Example 1 of this application;

[0029] Figure 4 To test the aqueous zinc-ion battery using the KVOH nanomaterials provided in Example 1 of this application at 0.2 A g... -1 GCD curves at current densities;

[0030] Figure 5 The rate performance diagram of an aqueous zinc-ion battery using the KVOH nanomaterial provided in Example 1 of this application is shown.

[0031] Figure 6 For an aqueous zinc-ion battery using the KVOH nanomaterials provided in Example 1 of this application, at 1 A g -1 and 5 Ag -1 Cyclic performance at current density. Detailed Implementation

[0032] This application provides a KVOH nanomaterial, its preparation method, and an aqueous zinc-ion battery to address the technical problem of low performance of vanadium pentoxide cathode materials in the prior art.

[0033] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Example 1

[0035] Example 1 of this application provides a method for preparing KVOH nanomaterials, the method including preparing a KVOH nanomaterial precursor solution and a solvothermal reaction.

[0036] The steps for preparing the KVOH nanomaterial precursor solution include: mixing 1 mL of ethylene glycol and 60 mL of deionized water as a solvent, adding 3 mmol of vanadium pentoxide and stirring until homogeneous, then adding 2.5 mmol of potassium hydroxide and stirring thoroughly to obtain a yellow mixed solution, which serves as the KVOH nanomaterial precursor solution.

[0037] The solvothermal reaction steps include: transferring the KVOH nanomaterial precursor solution to a reaction vessel, reacting at 200°C for 24 hours, and then centrifuging, washing with anhydrous ethanol, and drying at 70°C to obtain KVOH nanoribbon materials after natural cooling.

[0038] Example 2

[0039] Example 2 of this application provides a method for preparing KVOH nanomaterials, the method including preparing a KVOH nanomaterial precursor solution and a solvothermal reaction.

[0040] The steps for preparing the KVOH nanomaterial precursor solution include: mixing 0.6 mL of ethylene glycol and 60 mL of deionized water as a solvent, adding 3 mmol of vanadium pentoxide and stirring until homogeneous, then adding 2.5 mmol of potassium hydroxide and stirring thoroughly to obtain a yellow mixed solution, which serves as the KVOH nanomaterial precursor solution.

[0041] The solvothermal reaction steps include: transferring the KVOH nanomaterial precursor solution to a reaction vessel, reacting at 200°C for 12 hours, and then centrifuging, washing with anhydrous ethanol, and drying at 70°C to obtain KVOH nanoribbon materials after natural cooling.

[0042] Example 3

[0043] Example 3 of this application provides a method for preparing KVOH nanomaterials, the method including preparing a KVOH nanomaterial precursor solution and a solvothermal reaction.

[0044] The steps for preparing the KVOH nanomaterial precursor solution include: mixing 1 mL of ethylene glycol and 60 mL of deionized water as a solvent, adding 6 mmol of vanadium pentoxide and stirring evenly, then adding 4 mmol of potassium hydroxide and stirring thoroughly to obtain a yellow mixed solution, which is used as the KVOH nanomaterial precursor solution.

[0045] The solvothermal reaction steps include: transferring the KVOH nanomaterial precursor solution to a reaction vessel, reacting at 200°C for 24 hours, and then centrifuging, washing with anhydrous ethanol, and drying at 70°C to obtain KVOH nanoribbon materials after natural cooling.

[0046] Example 4

[0047] Example 4 of this application provides an aqueous zinc-ion battery; wherein the positive electrode is prepared using the KVOH nanomaterial prepared by the preparation method described in Example 1, and the negative electrode, separator and electrolyte are commercially available products.

[0048] The preparation process of the positive electrode for the aqueous zinc-ion battery includes: mixing the KVOH nanoribbon material obtained in Example 1 with conductive carbon black and polyvinylidene fluoride (PVDF) binder in a weight ratio of 7:2:1 in an n-methyl-2-pyrrolidone (NMP) solvent, grinding to form a slurry, and then scraping or printing the slurry onto a stainless steel wire mesh or titanium foil current collector to form the working electrode. The prepared working electrode is dried in a vacuum oven at 80°C for 12 h, and the mass loading of the KVOH nanoribbon material is 2.5 mg cm⁻¹. -2 .

[0049] The negative electrode uses commercially available zinc foil, the separator uses commercially available glass fiber filter paper, and the electrolyte uses commercially available 3M zinc trifluoromethanesulfonate (98%, Zn(CF3SO3)2) aqueous solution. Then, the positive electrode, negative electrode, separator and electrolyte are assembled into a button-type rechargeable aqueous zinc-ion battery.

[0050] Experimental Example 1

[0051] This application tests the KVOH nanomaterials prepared in Examples 1 and 4 and the aqueous zinc-ion battery.

[0052] The X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy results of the KVOH nanomaterials prepared in Example 1 are as follows: Figure 1-3 As shown; from Figure 1 The X-ray diffraction pattern shown indicates that the KVOH nanomaterials prepared in Example 1 are pure-phase monoclinic K... 0.48V₂O₅ crystals, when not completely dried, may contain some water; their chemical composition is K. 0.48 V₂O₅·1.6H₂O; from Figure 2 The scanning electron microscope images shown indicate that the KVOH nanomaterials have a width of 30–60 nm and a length of 100–500 nm; from Figure 2 The energy dispersive spectroscopy (EDS) spectrum shown indicates that the KVOH nanomaterials include potassium (K) and pentavalent vanadium (V). 5+ ), tetravalent vanadium (V 4+ The material contains elements such as potassium (O), oxygen (O), etc. Among them, potassium ions can act as a support, expanding the ion transport channels between layers, improving the stability of the material structure, and helping to improve the cycle performance of batteries using this material. Some tetravalent vanadium is due to the reducing properties of ethylene glycol in the aqueous solution of ethylene glycol. The product obtained after reducing pentavalent vanadium is beneficial to improving the specific capacity of the battery.

[0053] The performance test results of the KVOH nanomaterials prepared in Example 1 assembled into a button-type rechargeable aqueous zinc-ion battery are as follows: Figure 4-6 As shown; from Figure 4 It can be seen that the aqueous zinc-ion battery using KVOH nanoribbons as the positive electrode material provided in Example 1 of this application achieves a performance of 0.2 A g. -1 At a current density, it exhibits 700 mAh g -1 It exhibits an ultra-high initial discharge specific capacity, and the discharge specific capacity stabilizes at 620 mAh g after 5 cycles. -1 Further tests were conducted on the rate performance and cycle performance at higher current densities of the aqueous zinc-ion battery using KVOH nanoribbons as the cathode material provided in Example 1. The test results show that the aqueous zinc-ion battery using KVOH nanoribbons as the cathode material provided in this application has excellent rate performance and high cycle performance at high current.

[0054] The performance test results of KVOH nanomaterials and aqueous zinc-ion batteries demonstrate that aqueous zinc-ion batteries using KVOH nanoribbons as the cathode material provided in this application, due to the introduction of potassium ions as support, expand the ion transport channels between layers, effectively suppressing the structural distortion of the cathode material caused by zinc ion insertion-extraction, improving the stability of the layered structure, and enhancing the cycle stability of the battery. Simultaneously, ethylene glycol partially removes pentavalent vanadium (V... 5+ The reduction yielded tetravalent vanadium, which regulated the tetravalent vanadium content in the cathode material of KVOH nanoparticles and improved the specific capacity of zinc-ion batteries.

[0055] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 therein. Such 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 this application.

Claims

1. A method for preparing KVOH nanomaterials, characterized in that, The method comprises the steps of: In step S1, vanadium pentoxide and a potassium ion compound are dissolved in an ethylene glycol aqueous solution to obtain a KVOH nanomaterial precursor solution, wherein the volume ratio of ethylene glycol to deionized water in the ethylene glycol aqueous solution is 1:60-80. Step S2, performing a solvothermal reaction on the KVOH nanomaterial precursor solution to obtain a KVOH nanomaterial, the chemical composition of the KVOH nanomaterial being: K 0.48 V2O5·nH2O, 0≤n≤2.

2. The method for preparing KVOH nanomaterials according to claim 1, characterized in that, The KVOH nanomaterial has a morphology of a nanobelt.

3. The method for preparing KVOH nanomaterials according to claim 1, characterized in that, The KVOH nanomaterial has a width of 30-60 nm and a length of 100-500 nm.

4. The method of claim 1, wherein the KVOH nanomaterial is prepared by the method comprising the steps of: In step S2, the temperature of the solvothermal reaction is 180-220 DEG C, and the time is 8-30 h.

5. The method for preparing KVOH nanomaterials according to claim 1, characterized in that, After step S2, a post-treatment step S3 is further included. The post-treatment step comprises sequentially performing centrifugation, washing and drying.

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