A method for preparing oxygen-vacancy-rich vanadium-based nanoflowers for aqueous zinc-ion battery positive electrode materials

Abstract

The present invention discloses a method for preparing oxygen-vacancy vanadium-based nanoflowers for aqueous zinc ion battery positive electrode materials, which comprises firstly dissolving aspartic acid, zinc sulfate and ammonium vanadate in deionized water and performing a one-step hydrothermal reaction to obtain Zn 0.125 V2O5·H2O (ZVO), and then oxygen-rich Zn was obtained by calcination. 0.125 V2O5·H2O(O v The cathode material prepared by the present invention has stronger structural stability, high specific capacity, excellent cycle performance and energy density, indicating that the constructed battery system has great practical application potential.

Description

Technical Field

[0001] The present invention relates to the technical field of positive electrode materials for aqueous zinc ion batteries, and in particular to a method for preparing oxygen-vacancy-rich vanadium-based nanoflowers for positive electrode materials for aqueous zinc ion batteries. Background Art

[0002] Growing energy demands and worsening environmental problems necessitate the sustainable development of new energy sources. Rechargeable batteries with high charge-discharge efficiency, long cycle life, high power and energy density, pollution-free operation, and low maintenance costs can meet the demand for clean energy storage. Zinc-ion batteries, with their numerous advantages, including high volumetric capacity, simple fabrication process, safety, environmental friendliness, and abundant resources, are expected to become one of the leading next-generation electrochemical energy storage devices.

[0003] There are many cathode materials developed for aqueous zinc-ion batteries, but manganese-based materials have poor rate performance and Prussian blue analogs have low capacity. Compared with other types of cathode materials, vanadium-based compounds are considered to be the most competitive cathode materials for aqueous zinc-ion batteries due to their fast multi-electron redox reaction, high specific capacity, and good cycle stability. However, due to the high rate performance of Zn-based materials, the high specific capacity of Prussian blue analogs is the most competitive cathode material for aqueous zinc-ion batteries. 2+ There is a strong electrostatic interaction between zinc ions and vanadium-based materials, and the interlayer diffusion of zinc ions is slow, which seriously restricts its practical application. Summary of the Invention

[0004] In response to the above-mentioned problems currently existing in the vanadium-based positive electrode of aqueous zinc-ion batteries, the present invention provides a method for preparing oxygen-vacancy-rich vanadium-based nanoflowers for use as positive electrode materials for aqueous zinc-ion batteries. The prepared positive electrode material has stronger structural stability, high specific capacity, excellent cycle performance and energy density, demonstrating the practical application potential of the battery system.

[0005] To achieve the purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing oxygen-vacancy-rich vanadium-based nanoflowers for aqueous zinc-ion battery positive electrode materials comprises the following steps:

[0007] Step 1, dissolving aspartic acid L-Asp, zinc sulfate ZnSO4·7H2O and ammonium vanadate NH4VO3 in deionized water to obtain a mixed solution;

[0008] Step 2: Transfer the mixed solution obtained in step 1 to a reactor and heat it. After heating, cool it to room temperature. Centrifuge, wash, and dry the resulting suspension to obtain a precursor powder.

[0009] Step 3: heat-treating the precursor powder obtained in step 2 under an argon-hydrogen mixed atmosphere, and then naturally cooling it to room temperature to obtain oxygen-rich vacancy vanadium-based nanoflowers O for aqueous zinc ion battery positive electrode materials. v -ZVO.

[0010] Preferably, the specific method of step 1 is: heating deionized water to 60-80°C, then adding aspartic acid and zinc sulfate, and stirring at a constant temperature for 15-25 minutes until dissolved to obtain solution A; at the same time, heating deionized water to 60-80°C, then adding ammonium vanadate, and stirring at a constant temperature for 15-25 minutes until dissolved to obtain solution B; after solution A is completely dissolved, solution B is quickly added, and stirred at a constant temperature for 20 minutes to obtain a mixed solution.

[0011] Further preferably, in the solution A, the ratio of aspartic acid, zinc sulfate and deionized water is 0.10-0.15 g: 0.25-0.30 g: 10.0-20.0 mL; and in the solution B, the ratio of ammonium vanadate and deionized water is 0.10-0.15 g: 5.0-15.0 mL.

[0012] Preferably, in step 2, the heating temperature is 140-160° C., and the heating time is 4-8 hours.

[0013] Preferably, in step 2, the drying is vacuum drying, the drying temperature is 60-80° C., and the drying time is 4-8 hours.

[0014] Preferably, in step 3, the volume percentage of hydrogen in the argon-hydrogen mixed atmosphere is 5%, the heat treatment temperature is 200-300°C, the heat treatment time is 2-3h, and the heating rate is 2°C min -1 .

[0015] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0016] The present invention prepares a Zn 0.125 V2O5·H2O material, and oxygen vacancy-rich Zn was prepared by further annealing treatment. 0.125 In V2O5·H2O nanoflowers, the interaction between Zn and O atoms is weakened due to the introduction of oxygen vacancies. 2+ The diffusion barrier is reduced, which improves the electrochemical performance. v -ZVO cathode achieved high capacity and showed excellent cycling stability. This work helps to understand the Zn 2+ The intercalation / extraction and diffusion processes of ZIBs are investigated and provide a guiding strategy for designing high-performance ZIB cathode materials using defect engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 O prepared in Example 1 of the present invention v -Scanning electron microscopy images of ZVO nanoflowers, with insets corresponding to different magnifications;

[0018] Figure 2 O prepared in Example 1 of the present invention v - Transmission electron microscopy images of ZVO nanoflowers, with insets corresponding to different magnifications;

[0019] Figure 3 O prepared in Example 1 of the present invention v -Element distribution map of ZVO nanoflowers;

[0020] Figure 4 O prepared in Example 1 of the present invention v -X-ray diffraction pattern of ZVO nanoflowers;

[0021] Figure 5 O prepared in Example 1 of the present invention v -Thermogravimetric analysis curve of ZVO nanoflowers;

[0022] Figure 6 O prepared in Example 1 of the present invention v -Cyclic voltammetry curve of a 2032-type button battery constructed with ZVO nanoflowers as the positive electrode;

[0023] Figure 7 O prepared in Example 1 of the present invention v -Charge and discharge curves of a 2032-type button battery constructed with ZVO nanoflowers as the positive electrode;

[0024] Figure 8 The ZVO obtained in Comparative Example 1 (Figure (a)) of the present invention and the O obtained in Example 1 (Figure (b)) are v - Optical photo comparison of ZVO;

[0025] Figure 9 O obtained in Example 1 of the present invention v -Comparison of X-ray photoelectron spectra of ZVO and ZVO obtained in Comparative Example 1;

[0026] Figure 10 The pore size distribution curves (inset) and Brunauer-Emmet (BET) analysis of Example 1 (Figure (a)) of the present invention and Comparative Example 1 (Figure (b)) are shown;

[0027] Figure 11 The dissolution of Example 1 and Comparative Example 1 in 3M ZnSO4 is shown in the figure. The bottle on the left in each picture contains Comparative Example 1, and the bottle on the right contains Example 1.

[0028] Figure 121 is a cycle performance diagram of Example 1 of the present invention and Comparative Example 1;

[0029] Figure 13 1 is a rate performance diagram of Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0030] To further illustrate the present invention, the following detailed description of the preparation method of a novel high-performance aqueous zinc ion battery positive electrode material provided by the present invention, namely, oxygen vacancy-rich vanadium-based nanoflowers, is given in conjunction with the examples and illustrated in conjunction with the accompanying drawings, but it should not be understood as limiting the scope of protection of the present invention.

[0031] Example 1

[0032] In this example, oxygen-vacancy-rich vanadium-based nanoflowers were prepared according to the following steps:

[0033] Step 1. Dissolve 133.1 mg of L-Asp powder in 15 mL of 70°C deionized water, then add 287.56 mg of ZnSO₄·7H₂O and stir at constant temperature for 20 minutes to obtain Solution A. Simultaneously, dissolve 116.9 mg of NH₄VO₃ in 10 mL of 70°C deionized water and stir at constant temperature for 20 minutes to obtain Solution B. After Solution A is completely dissolved, quickly add Solution B, causing the solution to turn dark yellow. Stir at constant temperature for 20 minutes to obtain a mixed solution.

[0034] Step 2: Transfer the mixed solution to a 30 mL Teflon autoclave and heat at 150°C for 6 h. Cool to room temperature, collect the product, rinse with distilled water and ethanol in sequence, and then dry in a vacuum oven at 70°C for 6 h.

[0035] Step 3: Place the product in step 2 in a tube furnace at 240°C with 5% argon-hydrogen mixture for 3 hours. The heating rate of the tube furnace is 2°C min -1 After cooling naturally to room temperature, O v -ZVO Nanoflower.

[0036] Depend on Figure 1 It can be seen that the sample prepared in this embodiment presents a nanoflower structure with an average size of about 6 μm.

[0037] Figure 2 O obtained in this embodiment v -ZVO nanoflower transmission electron microscope image, the nanoflower is composed of nanobelts with a width of about 50nm, and O v -ZVO lattice fringes with a distance of 0.29 nm correspond to the triclinic (400) plane of ZVO.

[0038] Figure 3 O obtained in this embodiment vElement distribution diagram of -ZVO nanoflowers, where (a) is the microscopic morphology, (b) is the V element distribution diagram, (c) is the O element distribution diagram, and (d) is the Zn element distribution diagram. As can be seen from the figure, Zn, V, and O elements are evenly distributed.

[0039] Figure 4 O obtained in this embodiment v -ZVO nanoflower X-ray diffraction pattern, as shown in the figure, the prepared O v The XRD spectrum of -ZVO nanoflowers is dominated by (00l) plane reflection, indicating a high degree of preferred orientation.

[0040] Figure 5 O obtained in this embodiment v -Thermogravimetric analysis of ZVO nanoflowers. The TGA curve shows a weight loss of 8.2% in the temperature range of 100-350°C, indicating 0.95 mol of water per formulation unit.

[0041] Table 1 is the results of this example. v The elemental mass ratio of Zn to V in ZVO nanoflowers was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). v -ZVO, the element mass ratio of Zn to V in the discharged electrode and the charged electrode in the second charge-discharge cycle, and the chemical formula of the synthesized material is determined to be Zn 0.125 V2O5·H2O.

[0042] Table 1

[0043]

[0044] Using the O obtained in this embodiment v -ZVO nanoflowers were used as the positive electrode, zinc foil as the negative electrode, and 3M ZnCl2 solution as the electrolyte to assemble a 2032-type button cell. Cyclic voltammetry curves were tested on a CHI 660C electrochemical workstation. Figure 6 The cyclic voltammetry (CV) curve is shown in Figure 1. The cyclic voltammetry (CV) curve is plotted at 0.2 mV s -1 The scanning rate was 0.2-1.6V (vs. Zn / Zn 2+ ) within the voltage window, there are two pairs of redox peaks located at 1.08 / 0.89 V and 0.72 / 0.55 V, which are attributed to Zn 2+ The first three cycles of the CV curves overlap, indicating that Zn 2+ The embedding / de-embedding process is highly reversible.

[0045] Figure 7The charge and discharge distribution diagram of the 2032 button battery prepared in this example at different current densities. As can be seen from the figure, two pairs of charge and discharge platforms can still be observed even at high current density. This is because Zn 2+ The charge and discharge curves at different rates are similar in shape, indicating that Zn 2+ The ion (de)intercalation reaction is highly reversible, indicating that Zn||O v - Rapid charge transfer in ZVO batteries.

[0046] Comparative Example 1

[0047] In this embodiment, ZVO material is prepared according to the following steps:

[0048] Step 1. Dissolve 133.1 mg of L-Asp powder in 15 mL of 70°C deionized water, then add 287.56 mg of ZnSO₄·7H₂O and stir at constant temperature for 20 minutes to obtain Solution A. Simultaneously, dissolve 116.9 mg of NH₄VO₃ in 10 mL of 70°C deionized water and stir at constant temperature for 20 minutes to obtain Solution B. After Solution A is completely dissolved, quickly add Solution B, causing the solution to turn dark yellow. Stir at constant temperature for 20 minutes to obtain a mixed solution.

[0049] Step 2: Transfer the mixed solution to a 30 mL Teflon autoclave and heat at 150°C for 6 h. Cool to room temperature, collect the product, rinse with distilled water and ethanol, and then dry in a vacuum oven at 70°C for 6 h to obtain ZVO.

[0050] Figure 8 (a) with Figure 8 (b) are optical photos of the samples obtained in Comparative Example 1 and Example 1, respectively, showing that the prepared O v -ZVO is darker in color than ZVO.

[0051] Figure 9 is the XPS spectra of the samples obtained in Example 1 and Comparative Example 1, v The O1s XPS spectra of -ZVO and ZVO can be deconvoluted into three peaks at 530.5 eV, 531.5 eV, and 533.1 eV, which are assigned to VO bonds, oxygen vacancies, and -OH, O v The peak intensity of α-ZVO at 531.5 eV is significantly higher than that of ZVO, demonstrating the successful introduction of a large number of oxygen vacancies.

[0052] Figure 10 (a) with Figure 10 (b) are the pore size distribution curves (inset) and Brunauer-Emmet (BET) analysis of the samples obtained in Example 1 and Comparative Example 1, respectively. vThere are a large number of mesopores with an average pore size of 4 nm and 2 nm in ZVO-ZVO and ZVO, respectively. In addition, Brunauer-Emmet (BET) analysis shows that the introduction of oxygen vacancies increases the specific surface area and pore size. v - The surface area of ​​ZVO is 75.10m 2 g -1 , much higher than the surface area of ​​ZVO (44.37m 2 g -1 ).

[0053] Figure 11 The dissolution of the samples obtained in Example 1 and Comparative Example 1 in 3M ZnSO4 is shown. After immersing in ZVO for 60 days, a distinct yellow color can be observed in the solution; thanks to the introduction of oxygen vacancies, O v -ZVO's structure is more stable, soaked in O v -ZVO's ZnSO4 solution is still transparent.

[0054] Figure 12 The samples obtained in Example 1 and Comparative Example 1 were -1 Cycling performance under v -ZVO’s initial capacity can reach 375mAh g -1 , the capacity is basically maintained at the initial value after 50 cycles. However, the initial capacity of ZVO is only 320mAh g -1 , and the capacity decreases rapidly in the following 50 cycles.

[0055] Figure 13 The samples obtained in Example 1 and Comparative Example 1 are 0.1-3.0Ag -1 Rate performance at current density of 0.1, 0.2, 0.5, 1.0 and 2.0A -1 When O v The reversible specific capacities of ZVO can reach 402, 365, 345, 295, and 250 mAh g-1, respectively. -1 In 3Ag -1 At high rates, the capacity can still reach 250mAh g -1 When the current density returns to 0.2Ag -1 When O v -ZVO's capacity can be restored to 365mAh g -1 However, at the same current ratio, the capacity of ZVO is significantly lower than that of O v -ZVO.

[0056] The above are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing oxygen-vacancy-rich vanadium-based nanoflowers for aqueous zinc ion battery positive electrode materials, characterized in that: The following steps are involved: Step 1. Heat deionized water, then add aspartic acid and zinc sulfate, and stir at a constant temperature until dissolved to obtain solution A, wherein the amount ratio of aspartic acid, zinc sulfate and deionized water is 0.10-0.15 g: 0.25-0.30 g: 10.0-20.0 mL; at the same time, heat deionized water, then add ammonium vanadate, and stir at a constant temperature until dissolved to obtain solution B, wherein the amount ratio of ammonium vanadate and deionized water is 0.10-0.15 g: 5.0-15.0 mL; after solution A is completely dissolved, quickly add solution B, stir at a constant temperature until uniform, and obtain a mixed solution; Step 2: Transfer the mixed solution obtained in step 1 to a Teflon autoclave and heat it at a temperature of 140-160° C. for 4-8 h. After heating, cool it to room temperature. The resulting suspension is centrifuged, washed, and dried to obtain a precursor powder. Step 3: heat-treat the precursor powder obtained in step 2 in an argon-hydrogen mixed atmosphere at a temperature of 200-240 °C, a heat-treatment time of 2-3 h, and a heating rate of 2 °C min -1 After cooling naturally to room temperature, the oxygen-rich vacancy vanadium-based nanoflower O for aqueous zinc ion battery positive electrode materials is obtained. v -ZVO.

2. The preparation method according to claim 1, wherein: In step 1, the heating temperature for preparing solution A is 60-80°C and the stirring time is 15-25 min. The heating temperature for preparing solution B is 60-80°C and the stirring time is 15-25 min. The stirring time after mixing solution A and solution B is 20 min.

3. The preparation method according to claim 1, wherein: In step 2, the drying is vacuum drying, the drying temperature is 60-80° C., and the drying time is 4-8 h.

4. The preparation method according to claim 1, wherein: In step 3, the volume percentage of hydrogen in the argon-hydrogen mixed atmosphere is 5%.

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