Preparation method and application of vertical array W18O49 material

Abstract

The invention discloses a preparation method of a vertical array W18O49 material. The preparation method comprises the following steps: S1, measuring 30-50 mL of cycloethanol and 10-20 mL of acetylacetone, and uniformly mixing in a container to obtain a solution A; s2, adding 1-3 g of tungsten hexachloride into the solution A, and uniformly mixing to obtain a solution B; s3, transferring the solution B into a 100mL reaction kettle, sealing, putting into a drying oven, and carrying out hydrothermal reaction at 180-220 DEG C to obtain a product; and S4, carrying out suction filtration and washing on the obtained product through a solvent combination, and drying in a vacuum oven to obtain W18O49 powder. W18O49 can provide abundant active sites for capture and interaction of NaPSs, reaction dynamic characteristics of the battery are remarkably improved, more excellent cycling stability and rate performance are obtained, the reaction is easy to control, the product purity is high, purification through post-treatment is not needed, common materials which are low in price and easy to obtain are selected, the preparation cost is remarkably reduced, and the method is suitable for industrial production. And efficient conversion of energy can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery materials, and particularly relates to a preparation method and application of a vertical array WO 18 O 49 material. Background Art

[0002] With the accelerating advancement of the global industrialization process, the contradiction between the traditional fossil energy utilization mode and the sustainable development requirements has become increasingly prominent. The problems of resource waste and environmental pollution caused by low energy utilization efficiency have seriously threatened the sustainable development of human society. This practical dilemma has promoted the development of new energy technologies and the efficient conversion of clean energy to become the strategic focus of the global scientific research field. Among many energy storage technologies, the room temperature sodium-sulfur battery (RT Na-S) has become an important direction for the research of large-scale energy storage systems due to its excellent theoretical specific capacity (1675 mAh g -1 -1) and environmental friendliness, as well as the advantages of the crustal abundance of sodium and sulfur elements.

[0003] However, this system faces dual technical bottlenecks in practical applications: on the one hand, the slow electrochemical conversion kinetics of low-order polysulfide sodium (NaPSs) significantly restricts the capacity release of the battery; on the other hand, the dendrite growth problem of the sodium metal negative electrode not only affects the rate performance but also brings serious safety hazards. These key challenges directly hinder the commercialization process of RT Na-S batteries. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a vertical array WO 18 O 49 material. A large number of oxygen vacancies are exposed on the surface of the vertical array WO 18 O 49 material, which can provide abundant active sites for the capture and interaction of NaPSs, significantly improve the reaction kinetic characteristics of the battery, and obtain more excellent cycle stability and rate performance.

[0005] The present invention is realized through the following technical solutions:

[0006] A preparation method of a vertical array WO 18 O 49 material, comprising the following steps:

[0007] S1: Measure 30-50 mL of cyclohexanol and 10-20 mL of acetylacetone, mix them evenly in a container to obtain solution A;

[0008] S2: Add 1-3 g of tungsten hexachloride to solution A and mix them evenly to obtain solution B;

[0009] S3: Transfer solution B into a 100 mL reactor, seal it, and place it in an oven for hydrothermal reaction at 180 - 220 °C to obtain the product;

[0010] S4: After filtering and washing the obtained product with a solvent combination, dry it in a vacuum oven to obtain WO 18 O 49 powder.

[0011] Preferably, the mixing condition in step S2 is stirring at room temperature for 5 - 30 min.

[0012] Preferably, the time for the hydrothermal reaction in step S3 is 3 - 8 h.

[0013] Preferably, the combined solvent in step S4 uses ethanol and water.

[0014] Furthermore, the drying temperature in step S4 is 60 °C and the drying time is 0.5 h.

[0015] The WO 18 O 49 material prepared by the preparation method described in any one of the above is used in a sodium-sulfur battery, and the WO 18 O 49 material is used as a catalyst for the positive electrode plate of the sodium-sulfur battery.

[0016] The present invention has the following beneficial effects:

[0017] (1) The present invention adopts a one-step solvothermal method, the reaction is easy to control, the product purity is high, there is no need for post-treatment for purification, and the selected common materials are cheap and easily available, which can significantly reduce the preparation cost of the vertical array WO 18 O 49 material. Moreover, it has been proved by experiments that the yield is as high as 99.82%, and it is suitable for large-scale production, and can realize efficient energy conversion;

[0018] (2) The WO 18 O 49 material prepared by the present invention is a self-assembly of one-dimensional nanowires perpendicular to each other. The surface of the nanowires is coated with an amorphous layer, which has a large number of defects and is an excellent reactive active site. The one-dimensional nanowires perpendicular to each other have a large specific surface area, can expose a large number of oxygen vacancies, provide rich active sites for the capture and interaction of NaPSs, and at the same time, it is easier for electrons to be transported in two mutually perpendicular directions of the vertical array WO 18 O 49 material, significantly improving the reaction kinetic characteristics of the battery;

[0019] (3) The vertical array WO 18 O 49The material exhibits excellent catalytic performance when used as a catalyst for the positive electrode of a sodium-sulfur battery. In the voltage range of 0.2 - 3.0 V and at a large current density of 2 A g –1 it still shows a capacity of approximately 1000 mAh g –1 and also has excellent rate performance. Even at a current density of 10 A g –1 it still has a capacity of approximately 900 mAh g –1 . Description of the Drawings

[0020] Figure 1 This is the XRD pattern of the WO 18 O 49 material in Example 1 of the present invention;

[0021] Figure 2 This is the SEM pattern of the WO 18 O 49 material in Example 1 of the present invention;

[0022] Figure 3 This is the TEM pattern of the WO 18 O 49 material in Example 1 of the present invention;

[0023] Figure 4 This is the cycling performance of the WO 18 O 49 material in the examples of the present invention;

[0024] Figure 5 This is the rate performance of the WO 18 O 49 material in the examples of the present invention. Detailed Description of the Invention

[0025] The present invention will be further described in detail below with reference to specific examples. The following are explanations of the present invention rather than limitations.

[0026] Example 1:

[0027] Example 1 provides a method for preparing a vertical array of WO 18 O 49 material, and the preparation method is as follows:

[0028] S1: Measure 40 mL of cyclohexanol and 15 mL of acetylacetone and add them to a beaker, and stir for 5 min to obtain solution A;

[0029] S2: Add 2 g of tungsten hexachloride to solution A and stir at room temperature for 15 min to obtain solution B;

[0030] S3: Transfer solution B into a 100 mL reaction kettle, seal it and place it in an oven for hydrothermal reaction at 200 °C for 5 h to obtain the product;

[0031] S4: After the obtained product is filtered and washed with ethanol and water, it is dried in a vacuum oven at 60 °C for 0.5 h and collected to obtain WO 18 O 49 powder.

[0032] The product obtained in Example 1 was analyzed using a Rigaku D / max2000PC X-ray diffractometer. The XRD of the product is shown Figure 1 as follows. The peak positions are consistent with the standard cards, indicating that high-purity WO 18 O 49 .

[0033] The product was observed under a scanning electron microscope to obtain the SEM pattern of WO 18 O 49 material as shown Figure 2 below. It can be seen that the product presents a self-assembly of one-dimensional nanowires perpendicular to each other.

[0034] And from Figure 3 , the TEM pattern of WO 18 O 49 material shows that the surface of the nanowires of this product is coated with an amorphous layer with a large number of defects, providing more catalytic reaction active sites.

[0035] Example 2:

[0036] This Example 2 provides a preparation of a vertical array WO 18 O 49 material, and its preparation method is as follows:

[0037] S1: Measure 30, 35, 40, 45, 50 mL of cyclohexanol and 10, 15, 15, 15, 20 mL of acetylacetone and add them to a beaker, and stir for 5 min to obtain solution A;

[0038] S2: Add 1, 1.5, 2, 2.5, 3 g of tungsten hexachloride to solution A and stir at room temperature for 5, 10, 15, 20, 30 min to obtain solution B;

[0039] S3: Transfer solution B into a 100 mL reaction kettle, seal it and place it in an oven for hydrothermal reaction at 180, 190, 200, 210, 220 °C for 8, 6, 5, 4, 3 h to obtain the product;

[0040] S4: After the obtained product is filtered and washed with ethanol and water, it is dried in a vacuum oven at 60 °C for 0.5 h and collected to obtain WO 18 O49 Powder

[0041] Example 3:

[0042] This Example 3 provides a preparation of vertical array W 18 O 49 material, and the preparation method is as follows:

[0043] S1: Measure 35 mL of cyclohexanol and 15 mL of acetylacetone and add them to a beaker, stir for 5 min to obtain Solution A;

[0044] S2: Add 1.5 g of tungsten hexachloride to Solution A, stir at room temperature for 10 min to obtain Solution B;

[0045] S3: Transfer Solution B into a 100 mL autoclave, seal it and place it in an oven for hydrothermal reaction at 190 °C for 6 h to obtain the product;

[0046] S4: After the obtained product is filtered and washed with ethanol and water, it is dried in a vacuum oven at 60 °C for 0.5 h to collect the W 18 O 49 powder

[0047] Example 4:

[0048] This Example 4 provides a preparation of vertical array W 18 O 49 material, and the preparation method is as follows:

[0049] S1: Measure 45 mL of cyclohexanol and 15 mL of acetylacetone and add them to a beaker, stir for 5 min to obtain Solution A;

[0050] S2: Add 2.5 g of tungsten hexachloride to Solution A, stir at room temperature for 20 min to obtain Solution B;

[0051] S3: Transfer Solution B into a 100 mL autoclave, seal it and place it in an oven for hydrothermal reaction at 210 °C for 4 h to obtain the product;

[0052] S4: After the obtained product is filtered and washed with ethanol and water, it is dried in a vacuum oven at 60 °C for 0.5 h to collect the W 18 O 49 powder

[0053] Example 5:

[0054] This Example 5 provides a preparation of vertical array W 18 O 49 material, and the preparation method is as follows:

[0055] S1: Measure 50 mL of cyclohexanol and 20 mL of acetylacetone, add them to a beaker, and stir for 5 min to obtain solution A;

[0056] S2: Add 3 g of tungsten hexachloride to solution A, and stir at room temperature for 30 min to obtain solution B;

[0057] S3: Transfer solution B into a 100 mL autoclave, seal it, and place it in an oven for hydrothermal reaction at 220 °C for 3 h to obtain the product;

[0058] S4: After the obtained product is filtered and washed with ethanol and water, it is dried in a vacuum oven at 60 °C for 0.5 h, and the WO powder is collected. 18 O 49 powder.

[0059] In summary, the prepared WO 18 O 49 material is a self-assembly of one-dimensional nanowires perpendicular to each other. The surface of the nanowires is coated with an amorphous layer, which has a large number of defects and can provide rich reactive sites for the capture and interaction of NaPSs. Therefore, it is used as a catalyst for the positive electrode of a sodium-sulfur battery, and a button-type sodium-sulfur battery is prepared. The specific steps are as follows:

[0060] (1) Place the prepared WO 18 O 49 powder and sublimed sulfur powder in a 1:2 ratio in an autoclave, seal it, and react in an oven at 155 °C for 12 h to obtain the active powder;

[0061] (2) Grind the active powder, conductive agent (Super P), carbon nanotubes, and binder (polyvinylidene fluoride PVDF) evenly according to a mass ratio of 7:1:1:1;

[0062] (3) Then add an appropriate amount of solvent NMP, continue to stir and grind to dissolve the binder fully in NMP, and mix it evenly with other components to form a slurry;

[0063] (5) Use a film applicator to coat the slurry evenly on the copper foil, and then place the copper foil in a vacuum drying oven at 80 °C for 24 h to obtain the electrode sheet;

[0064] (6) Assemble the electrode sheet into a button battery in a glove box.

[0065] Use a Neware electrochemical workstation to perform constant current charge and discharge tests on the prepared sodium-sulfur button battery. The test voltage is 0.2 - 3.0 V. As Figure 4 shown, the battery exhibits a capacity of about 1000 mAh g –1 at a current density of 2 A g –1 after 350 cycles. Its rate performance is asFigure 5 As shown, the capacity of the battery is relatively stable at different current densities. Even at a current density of 10 A g –1 it still has a capacity of approximately 900 mAh g –1 . That is, when returning to a low current density, the capacity can be maintained, indicating good rate performance and cycle stability.

[0066] The above content is a further detailed description of the present invention in combination with specific embodiments. It cannot be determined that the specific implementation of the present invention is limited only to these embodiments. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A vertical array W 18 O 49 The method for preparing the material is characterized in that: The following steps are involved: S1: Measure 30-50 mL of cyclohexanol and 10-20 mL of acetylacetone and mix them evenly in a container to obtain solution A; S2: Add 1-3 g of tungsten hexachloride to solution A and mix evenly to obtain solution B; S3: Transfer solution B into a 100 mL reactor, seal it and place it in an oven for hydrothermal reaction at 180-220°C to obtain a product; S4: The obtained product is filtered and washed with the solvent combination, and then dried in a vacuum oven to obtain W 18 O 49 Powder.

2. A vertical array W according to claim 1 18 O 49 The method for preparing the material is characterized in that: The mixing condition in step S2 is stirring at room temperature for 5 to 30 minutes.

3. A vertical array W according to claim 1 18 O 49 The method for preparing the material is characterized in that: The time of the hydrothermal reaction in step S3 is 3 to 8 hours.

4. A vertical array W according to claim 1 18 O 49 The method for preparing the material is characterized in that: The combined solvent in step S4 is ethanol and water.

5. A vertical array W according to claim 4 18 O 49 The method for preparing the material is characterized in that: The drying temperature in step S4 is 60° C. and the drying time is 0.5 h.

6. W prepared by the preparation method according to any one of claims 1 to 5 18 O 49 The application of the material in sodium-sulfur batteries is characterized in that: The W 18 O 49 The material is used as a catalyst for the positive electrode of sodium-sulfur batteries.

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