A method for preparing vanadium oxide containing oxygen defects at low temperature
The preparation of vanadium oxide materials containing oxygen defects by low-temperature water bath method solves the problems of poor conductivity of vanadium-based oxides and slow diffusion of zinc ions, improves the electrochemical performance and production efficiency of water-based zinc ion batteries, and is suitable for large-scale production.
Patent Information
- Application Number
- CN202211724908.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-30
- Publication Date
- 2025-07-25
- Estimated Expiration
- 2042-12-30
AI Technical Summary
In the prior art, when preparing the positive electrode material of a water-based zinc ion battery, vanadium-based oxides have poor conductivity and slow diffusion kinetics of zinc ions, resulting in poor electrochemical performance, and high-temperature hydrothermal reaction and annealing treatment, which is not suitable for large-scale production.
Vanadium oxide containing oxygen defects was prepared by low-temperature water bath method. By dissolving vanadium pentoxide in water and adding thiourea and an acidic solution, a solution of specific colors was formed and stirred in a water bath, and then dried to obtain a dark green powder vanadium oxide material.
It improves the conductivity of the material and the zinc ion deintercalation ability, enhances the cyclic stability and specific capacity of the material, achieves zinc storage capacity and long cycle life above 400mAh/g, and at the same time reduces production costs, making it suitable for large-scale preparation.
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for preparing vanadium oxide containing oxygen defects, and particularly to a method for preparing vanadium oxide containing oxygen defects at low temperature. Background Art
[0002] There are various cathode materials for aqueous zinc-ion batteries, and commonly used ones are vanadium-based materials. However, vanadium-based oxides have poor electrical conductivity, and the strong electrostatic interaction between divalent zinc ions and the materials will lead to problems such as slow zinc ion diffusion kinetics and low material structure stability, seriously affecting and restricting the electrochemical performance of vanadium-based oxides.
[0003] Liang et al. synthesized vanadium pentoxide with oxygen defects through a hydrothermal reaction at 180 °C and subsequent annealing treatment at 350 °C. As a cathode material for aqueous zinc-ion batteries, the capacity is 362 mAh / g at a current density of 0.13 A / g (NanoEnergy, 2021, 87, 106164). Zhu et al. synthesized a vanadium dioxide cathode material with oxygen defects through a hydrothermal reaction at 200 °C and subsequent calcination treatment at 600 °C, with 196 mAh / g at a current density of 0.1 A / g (Nature Communication, 2021, 12, 27203). Most of the existing methods require hydrothermal reactions above 100 °C or high-temperature annealing treatments, with high production costs, complicated methods, and low yields, which are not conducive to large-scale mass production. Summary of the Invention
[0004] Object of the Invention: To provide a method for preparing vanadium oxide containing oxygen defects at low temperature with low cost and simple operation.
[0005] Technical Solution: The method for preparing vanadium oxide containing oxygen defects at low temperature according to the present invention has the following steps:
[0006] (1) Dissolve vanadium pentoxide in water to form an orange-yellow solution;
[0007] (2) Dissolve thiourea in the solution of step (1) to form a light orange-yellow solution;
[0008] (3) Add an acidic solution to the solution of step (2) to form a light green solution;
[0009] (4) Stir the solution of step (3) in a water bath at 75-95 °C to obtain a dark green solution, stand still and dry to obtain a dark green powdery vanadium oxide containing oxygen defects.
[0010] Furthermore, the concentration of vanadium pentoxide is 0.03-0.15 mol / L; the molar ratio range of vanadium pentoxide to thiourea is 4-0.5.
[0011] Further, the pH value range of the light green solution in step (3) is 0-4.
[0012] Further, the acidic solution in step (3) is any one of hydrochloric acid, sulfuric acid, and acetic acid.
[0013] Further, the drying condition in step (4) is a vacuum environment, and the drying temperature is controlled within 60-80°C.
[0014] Further, in steps (1), (2), and (3), stirring is carried out under a water bath condition of 30-60°C to form a uniformly mixed solution.
[0015] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: (1) The defective vanadium oxide cathode material for aqueous zinc ions of the present invention is a layered vanadium oxide material with oxygen defects and crystal water (V 10 O 24-x ·12H2O, 0<x<24), and the morphology is intertwined nanoribbons. The crystal water and oxygen defects expand the layer spacing of the vanadium oxide structure, and the oxygen defects weaken the electrostatic interaction between the host material and zinc ions, which are more conducive to the deintercalation and intercalation of zinc ions, improving the cycle stability and cycle life of the material; in addition, the oxygen defects can also improve the conductivity of the material and increase the zinc intercalation sites of the material, thereby improving the rate performance of the material and obtaining a higher specific capacity. The oxygen-deficient vanadium oxide synthesized in the present invention is used as the cathode to assemble an aqueous zinc ion battery, and its zinc storage capacity can be higher than 400 mAh / g and has a long cycle life; (2) The method of the present invention has a simple process, and it is easy to prepare vanadium oxide containing oxygen defects only by a low-temperature water bath at 75-95°C, which can be used for large-scale preparation and has obvious economic benefits. Description of the Drawings
[0016] Figure 1 XRD patterns of oxygen-deficient vanadium oxides prepared in Examples 1, 2, and 3;
[0017] Figure 2 SEM image of the oxygen-deficient vanadium oxide prepared in Example 1;
[0018] Figure 3 XPS O1s diffraction pattern of the oxygen-deficient vanadium oxide prepared in Example 1;
[0019] Figure 4 EPR spectra of vanadium oxides prepared in Examples 1, 2, 3, and Comparative Example 1;
[0020] Figure 5Cycling performance graphs of the vanadium oxide cathode materials prepared in Examples 1, 2, 3 and Comparative Example 1 at a current density of 0.5 A / g;
[0021] Figure 6 Rate performance graphs of the vanadium oxide cathode materials prepared in Examples 1, 2, 3 and Comparative Example 1;
[0022] Figure 7 Long cycling performance graphs of the vanadium oxide cathode materials prepared in Examples 1, 2, 3 and Comparative Example 1 at a current density of 10 A / g;
[0023] Figure 8 XRD pattern of V2O5 prepared in Comparative Example 1;
[0024] Figure 9 SEM image of V2O5 prepared in Comparative Example 1. Detailed implementation manners
[0025] The technical solutions of the present invention will be further described below in conjunction with the examples and the drawings.
[0026] Example 1:
[0027] (1) Put 2 mmol of vanadium oxide V2O5 into a beaker, add 50 ml of deionized water, and perform water bath stirring at 70 °C for 10 min to form an orange-yellow solution, referred to as solution A;
[0028] (2) Add 0.5 mmol of thiourea to solution A prepared in the water bath stirring step (1), and continue to stir for 10 min under the water bath conditions of step (1) to form a light orange-yellow solution, referred to as solution B;
[0029] (3) Drop 0.2 ml of a dilute sulfuric acid solution with a molar concentration of 2 mol / L into solution B prepared in step (2), and continue to stir for 15 min under the water bath conditions of step (1) to form a light green solution, referred to as solution C;
[0030] (4) Continue to stir solution C formed in step (3) in a water bath at 90 °C for 2 h to obtain a dark green solution, let it stand at room temperature for 30 min, and wash the reaction product 4 times alternately with ethanol and deionized water; then set the vacuum drying oven at 60 °C and heat for 18 h to obtain a dark green powdery product, namely vanadium oxide with oxygen defects (V 10 O 24-x ·12H2O, 0 < x < 24).
[0031] The XRD pattern of the vanadium oxide with oxygen defects prepared in this example is shown in Figure 1 , and the cathode material prepared by XRD analysis is V 10 O 24-x·12H2O, as shown in the scanning electrode diagram Figure 2 The material shows intertwined nanoribbons. The XPS O1s diagram and the EPR diagram are shown in Figure 3 and Figure 4 respectively, verifying the existence of oxygen defects in the material.
[0032] Take the vanadium oxide containing oxygen defects prepared by the method of this example, Superp Li (superconductive carbon black) and polytetrafluoroethylene, and mix the raw material components in a ratio of 7:2:1. Add the dispersant NMP to the ball milling tank and ball mill for 6 h, then draw into a film. Under vacuum conditions, dry at 60 °C for 18 h to obtain the positive electrode sheet of the aqueous zinc-ion battery. In air, use metallic zinc as the negative electrode, 3 mol / L zinc trifluoromethanesulfonate as the electrolyte, glass fiber as the separator, and titanium mesh as the current collector to assemble a button battery for electrochemical performance testing. When testing, the range of the charge-discharge current density is 0.2 - 10 A / g, and the charge-discharge cut-off voltage is 0.2 - 1.6 V (vs. Zn 2+ / Zn).
[0033] The performance of the zinc-ion battery prepared by the method of this example at a current density of 0.5 A / g is as shown in Figure 5 The initial discharge specific capacity is 391 mAh / g, and the capacity retention rate is as high as 76% after 300 cycles. The rate performance is shown in Figure 6 The material still shows a specific capacity of 270 mAh / g at a high current density of 10 A / g. After cycling 3000 times at a current density of 10 A / g, there is still a capacity retention rate of 67%, as shown in Figure 7 specifically.
[0034] Example 2
[0035] The specific steps are basically the same as those in Example 1. The main difference is that the addition amount of thiourea in step (2) is changed to 1.5 mmol. The XRD pattern of the obtained vanadium oxide containing oxygen defects is shown in Figure 1 After XRD analysis, the prepared positive electrode material is V 10 O 24-x ·12H2O, as shown in Figure 4 verifying the existence of oxygen defects in the material; Take the vanadium oxide containing oxygen defects prepared by the method of this example to prepare the positive electrode sheet of the zinc-ion battery. The performance at a current density of 0.5 A / g is as shown in Figure 5 The initial discharge specific capacity is 413 mAh / g, and the capacity retention rate is as high as 80% after 300 cycles. The rate performance is shown in Figure 6 At a high current density of 10 A / g, the specific capacity reaches a high value of 303 mAh / g, and after cycling 3000 times, there is still a capacity retention rate of 77%, as shown in Figure 7 specifically.
[0036] Example 3
[0037] The specific steps are basically the same as those in Example 1. The main difference is that the addition amount of thiourea in step (2) is changed to 2 mmol. The XRD pattern of vanadium oxide containing oxygen vacancies obtained is shown in Figure 1 , and the cathode material prepared by XRD analysis is V 10 O 24-x ·12H2O, as shown in Figure 4 ; The existence of oxygen vacancies in the material is verified; The vanadium oxide containing oxygen vacancies prepared by the method of this example is made into a zinc ion battery cathode sheet, and its performance at a current density of 0.5 A / g is shown in Figure 5 ; The rate performance is shown in Figure 6 , and the specific capacity at a high current density of 10 A / g is specifically shown in Figure 7 .
[0038] Comparative Example 1
[0039] The specific steps are basically the same as those in Example 1. The main difference is that step (2) is removed and thiourea is not added during the preparation process. Finally, a vanadium oxide material is obtained, and its XRD pattern is shown in Figure 8 , and the cathode material prepared by XRD analysis is V2O5, and its morphology is shown in Figure 9 , which is a block material. The EPR pattern is shown in Figure 4 , and there are basically no oxygen vacancies. V2O5 is made into a vanadium-based cathode for an aqueous zinc ion battery according to the electrode preparation method in Example 1. In air, metallic zinc is used as the anode, 3M zinc trifluoromethanesulfonate is used as the electrolyte, glass fiber is used as the separator, and titanium mesh is used as the current collector to assemble a button battery for electrochemical performance testing. The range of the charge-discharge current density during the test is 0.2 - 10 A / g, and the charge-discharge cut-off voltage is 0.2 - 1.6 V (vs. Zn 2+ / Zn); The performance of the cathode material obtained in Comparative Example 1 at a current density of 0.5 A / g is shown in Figure 5 ; The rate performance is shown in Figure 6 , and the specific capacity at a high current density of 10 A / g is specifically shown in Figure 7 . Its cycle stability and specific capacity have a large gap compared with Examples 1, 2, and 3, further proving the improvement of the electrochemical performance of the material by the introduction of oxygen vacancies.
Claims
1. A method for preparing vanadium oxide containing oxygen defects at low temperature, characterized in that, The preparation method steps are as follows: (1) Dissolve vanadium pentoxide in water to form an orange-yellow solution; (2) Dissolve thiourea in the solution of step (1) to form a light orange-yellow solution; the molar ratio range of vanadium pentoxide to thiourea is 4 to 0.5; (3) Add an acidic solution to the solution of step (2) to form a light green solution; (4) Stir the solution of step (3) in a water bath at 75-95 °C to obtain a dark green solution, let it stand and dry to obtain a dark green powdery vanadium oxide containing oxygen defects.
2. The method for preparing vanadium oxide containing oxygen defects at low temperature according to claim 1, wherein The concentration of the vanadium pentoxide is 0.03-0.15 mol / L.
3. The method for preparing vanadium oxide containing oxygen defects at low temperature according to claim 1, characterized in that, The pH value range of the light green solution in step (3) is 0-4.
4. The method for preparing vanadium oxide containing oxygen defects at low temperature according to claim 1, characterized in that, The acidic solution in step (3) is any one of hydrochloric acid, sulfuric acid, and acetic acid.
5. The method for preparing vanadium oxide containing oxygen defects at low temperature according to claim 1, characterized in that, The drying condition in step (4) is a vacuum environment, and the drying temperature is controlled within 60-80 °C.
6. The method for preparing vanadium oxide containing oxygen defects at low temperature according to claim 1, characterized in that, In steps (1), (2), and (3), stirring is carried out under a water bath condition of 30-60 °C to form a uniformly mixed solution.