Vanadium pentoxide composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a vanadium pentoxide composite material and a preparation method and application thereof. The preparation method comprises the following steps: mixing ammonium metavanadate, a coating agent and a solvent, carrying out hydrothermal reaction to obtain a precursor, and sintering the precursor to obtain the vanadium pentoxide composite material, wherein the conditions of the hydrothermal reaction are as follows: the temperature is 170-185 DEG C, and the time is 2-5 hours; the vanadium pentoxide composite material prepared from ammonium metavanadate under a specific hydrothermal condition has a large specific surface area and a short ion diffusion path, a coating agent is added to realize coating, a high-efficiency electron conduction network is formed, and the vanadium pentoxide composite material has excellent capacity performance and cycling stability due to the synergistic effect of the coating agent and the high-efficiency electron conduction network.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a vanadium pentoxide composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of electric vehicles and portable electronic products, the market has placed higher demands on the energy density, power density, and cycle life of lithium-ion batteries. As a key component determining battery performance and cost, the technological innovation of cathode materials is particularly urgent. Developing novel cathode materials that combine high capacity, high stability, and excellent rate performance has become a current research hotspot and a core driving force for industrial development.

[0003] Vanadium pentoxide (V₂O₅) is a cathode material for lithium-ion batteries, possessing a theoretically high capacity (approximately 440 mAh g⁻¹). -1 It has advantages such as abundant raw materials and low cost. However, its intrinsic electronic conductivity is low (10⁻⁶). -3 Up to 10 -2 S cm -1 And the lithium-ion diffusion coefficient is small (approximately 10). -12 cm 2 s -1 The problem of [missing information] severely limits its capacity performance and cycle stability. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of poor capacity performance and cycle stability of existing vanadium pentoxide cathode materials, thereby providing a vanadium pentoxide composite material, its preparation method and application.

[0005] Therefore, the present invention provides the following technical solution: The first aspect of this invention protects a method for preparing vanadium pentoxide composite material, wherein the preparation method includes the following steps: mixing ammonium metavanadate, a coating agent and a solvent and carrying out a hydrothermal reaction to obtain a precursor, and sintering the precursor to obtain the vanadium pentoxide composite material; The conditions for the hydrothermal reaction include: a temperature of 170-185℃ and a time of 2-5 hours.

[0006] As an example, the temperature of the hydrothermal reaction can be 170°C, 172°C, 174°C, 176°C, 180°C, 182°C, 185°C, or within any range of the above values; the time can be 2h, 3h, 4h, 5h, or within any range of the above values.

[0007] In this invention, ammonium metavanadate can be dissolved in a solvent first, and then a carbon source and a nitrogen source can be added; alternatively, ammonium metavanadate, a carbon source, and a nitrogen source can be mixed first, and then dissolved in a solvent. The mixing order is not limited, as long as the mixture is homogeneous.

[0008] This invention selects ammonium metavanadate as the precursor raw material for vanadium pentoxide and carries out a hydrothermal reaction under specific hydrothermal conditions to obtain the precursor. The precursor is then sintered, undergoing phase transformation and structural reconstruction during high-temperature sintering to obtain a vanadium pentoxide composite material. This vanadium pentoxide composite material has a large specific surface area, increasing the contact area between the material and the electrolyte and providing sufficient active sites for ion adsorption and desorption. It also has a short ion diffusion path, effectively reducing resistance during ion migration and accelerating the ion transport rate. Furthermore, the addition of a coating agent achieves coating, forming a highly efficient electron conduction network and improving the material's electron conduction efficiency. The synergistic effect of these two factors results in the vanadium pentoxide composite material exhibiting excellent capacity performance and cycle stability.

[0009] In some alternative embodiments, the conditions for the hydrothermal reaction include a temperature of 175-180°C and a time of 3-4 hours.

[0010] As an example, the temperature of the hydrothermal reaction can be 175°C, 176°C, 177°C, 178°C, 179°C, 180°C, or any of the above values; the time can be 3h, 3.5h, 4h, or any of the above values.

[0011] In some alternative embodiments, the coating agent includes a carbon source and / or a nitrogen source.

[0012] In some optional embodiments, the mass ratio of ammonium metavanadate to carbon source is (0.1-1):(0.1-0.5), optionally (0.5-0.8):0.1, and further optionally 0.7:0.1.

[0013] In some optional embodiments, the mass ratio of ammonium metavanadate to nitrogen source is (0.1-1):(0.1-0.5), optionally (0.5-0.8):0.1, and further optionally 0.7:0.1.

[0014] In this invention, the carbon source and nitrogen source are conventional materials in the art. Typically, without limitation, the carbon source includes at least one of glucose, sucrose, citric acid, tartaric acid, starch, and cellulose; and the nitrogen source includes at least one of ethylenediamine, ammonium chloride, and diethylenetriamine.

[0015] In this invention, when the coating agent is a carbon source and a nitrogen source, the introduction of nitrogen atoms not only significantly improves the electronic conductivity of the carbon layer, but also enhances the adsorption and intercalation capabilities of lithium ions through the defects and active sites (such as pyridine nitrogen) generated therefrom, thus achieving a dual improvement in electron and ion transport capabilities.

[0016] In some alternative embodiments, the solvent includes water and ethylene glycol, with the water being standard laboratory water, such as deionized water.

[0017] In some alternative embodiments, the volume ratio of water to ethylene glycol is (1-10):1.

[0018] In this invention, the amounts of ammonium metavanadate and solvent can be adjusted according to actual conditions. Typically, without limitation, the solid-liquid ratio of ammonium metavanadate to solvent is 0.7g:(50-100)mL.

[0019] In some alternative embodiments, the sintering conditions include: heating to 380-450°C at a rate of 1-3°C / min and holding for 3-5 hours under nitrogen atmosphere.

[0020] In some alternative embodiments, the precursor is further dried before sintering; In some alternative embodiments, the drying conditions include drying at 80-100°C for 8-12 hours.

[0021] A second aspect of the present invention protects a vanadium pentoxide composite material as described above, wherein the vanadium pentoxide composite material comprises a core and a coating layer covering the core; The core is a three-dimensional flower-shaped vanadium pentoxide sphere.

[0022] In some alternative embodiments, the three-dimensional flower-shaped vanadium pentoxide spheres comprise nanosheets and nanoparticles, wherein the nanosheets and nanoparticles are mixed and stacked in the form of a mixture.

[0023] In this invention, SEM (Scanning Electron Microscopy) observation reveals that the three-dimensional flower-like vanadium pentoxide spheres exhibit a spherical outline, formed by the disordered stacking of nanosheets and nanoparticles, possessing complete three-dimensional spatial distribution characteristics. The surface displays an open-pore structure, resembling the three-dimensional form of a blooming flower. These three-dimensional flower-like vanadium pentoxide spheres, as a vanadium pentoxide composite material, possess a large specific surface area, increasing the contact area between the material and the electrolyte, providing ample active sites for ion adsorption and desorption. They also have short ion diffusion paths, effectively reducing resistance during ion migration and accelerating ion transport rates. Furthermore, the addition of a coating agent achieves coating, forming a highly efficient electron conduction network, improving the material's electron conduction efficiency. The synergistic effect of these two factors results in the vanadium pentoxide composite material exhibiting excellent capacity performance and cycle stability.

[0024] In some alternative embodiments, the coating layer is made of carbon.

[0025] In some alternative embodiments, the coating layer is made of nitrogen.

[0026] In some alternative embodiments, the coating layer is made of carbon and nitrogen.

[0027] In this invention, XPS (X-ray photoelectron spectroscopy) is used to detect the elemental composition of the coating material.

[0028] A third aspect of this invention protects a secondary battery, wherein the secondary battery comprises the vanadium pentoxide composite material prepared by the aforementioned preparation method or the aforementioned vanadium pentoxide composite material.

[0029] The technical solution of this invention has the following advantages: 1. This invention provides a method for preparing vanadium pentoxide composite material, wherein the preparation method includes the following steps: mixing ammonium metavanadate, a coating agent, and a solvent to carry out a hydrothermal reaction to obtain a precursor, and sintering the precursor to obtain the vanadium pentoxide composite material; wherein the hydrothermal reaction conditions include: a temperature of 170-185℃ and a time of 2-5h; this invention selects ammonium metavanadate as the precursor raw material for vanadium pentoxide, and carries out a hydrothermal reaction under specific hydrothermal conditions to obtain the precursor; then the obtained precursor is sintered, and through phase transformation and structural reconstruction during the high-temperature sintering process, the vanadium pentoxide composite material is obtained. The vanadium pentoxide composite material has a large specific surface area, which can increase the contact area between the material and the electrolyte, providing sufficient active sites for ion adsorption and desorption; it has a short ion diffusion path, which effectively reduces the resistance during ion migration and accelerates the ion transport rate; and the addition of a coating agent achieves coating, forming a highly efficient electron conduction network, improving the electron conduction efficiency of the material. The synergistic effect of these two factors gives the vanadium pentoxide composite material excellent capacity performance and cycle stability.

[0030] 2. In this invention, when the coating agent is a carbon source and a nitrogen source, the introduction of nitrogen atoms not only significantly improves the electronic conductivity of the carbon layer, but also enhances the adsorption and intercalation capabilities of lithium ions through the defects and active sites (such as pyridine nitrogen) generated therefrom, thus achieving a dual improvement in electron and ion transport capabilities.

[0031] 3. This invention provides a vanadium pentoxide composite material, wherein the vanadium pentoxide composite material includes a core and a coating layer covering the core; the core is a three-dimensional flower-shaped vanadium pentoxide sphere; the vanadium pentoxide composite material has a large specific surface area, which can increase the contact area between the material and the electrolyte, providing sufficient active sites for ion adsorption and desorption; it has a short ion diffusion path, effectively reducing the resistance in the ion migration process and accelerating the ion transport rate; and the addition of a coating agent achieves coating, forming a highly efficient electron conduction network, improving the electron conduction efficiency of the material. The synergistic effect of these two factors gives the vanadium pentoxide composite material excellent capacity performance and cycle stability. Detailed Implementation

[0032] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof in the text of this application are intended to cover non-exclusive inclusion.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter can be, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0036] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0037] In the description of the embodiments of this application, the term "at least one" refers to one or more (including two).

[0038] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0039] Example 1 This embodiment provides a vanadium pentoxide composite material, the preparation method of which includes the following steps: Ammonium metavanadate was dissolved in a mixed solvent of deionized water and ethylene glycol in a volume ratio of 1:1, with a solid-liquid ratio of 0.7 g: 60 mL to obtain a mixed solution. Glucose and ammonium chloride were then added, with a mass ratio of 0.7:0.1:0.1. The mixture was magnetically stirred until completely dissolved. The solution was transferred to a high-pressure reactor and reacted at 180 °C for 4 h. After the reaction, the product was dried at 80 °C for 12 h. Finally, under a nitrogen atmosphere, the temperature was increased to 400 °C at a rate of 2 °C / min and held for 3 h to obtain a vanadium pentoxide composite material. SEM analysis revealed that the vanadium pentoxide composite material consists of a core and a coating layer covering the core. The core is a three-dimensional flower-like vanadium pentoxide sphere, which comprises disordered stacked nanosheets and nanoparticles. The coating layer consists of carbon and nitrogen elements.

[0040] Example 2 This embodiment provides a vanadium pentoxide composite material, the preparation method of which includes the following steps: Following the method of Example 1, the difference is that the solution is transferred to a high-pressure reactor and reacted at 170°C for 5 hours; finally, a vanadium pentoxide composite material is obtained; SEM testing shows that the vanadium pentoxide composite material includes a core and a coating layer covering the core. The core is a three-dimensional flower-shaped vanadium pentoxide sphere, and the three-dimensional flower-shaped vanadium pentoxide sphere includes disordered stacked nanosheets and nanoparticles. The coating layer is made of carbon and nitrogen elements.

[0041] Example 3 This embodiment provides a vanadium pentoxide composite material, the preparation method of which includes the following steps: Ammonium metavanadate was dissolved in a mixed solvent of deionized water and ethylene glycol at a volume ratio of 1:1, with a solid-liquid ratio of 0.7 g: 60 mL, to obtain a mixed solution. Glucose was then added, with a mass ratio of ammonium metavanadate to glucose of 0.7:0.2. The mixture was magnetically stirred until completely dissolved. The solution was transferred to a high-pressure reactor and reacted at 180 °C for 4 h. After the reaction, the product was dried at 80 °C for 12 h. Finally, under a nitrogen atmosphere, the temperature was increased to 400 °C at a rate of 2 °C / min and held for 3 h to obtain a vanadium pentoxide composite material. SEM analysis revealed that the vanadium pentoxide composite material consists of a core and a coating layer covering the core. The core is a three-dimensional flower-like vanadium pentoxide sphere, which comprises disordered stacked nanosheets and nanoparticles. The coating layer consists of carbon.

[0042] Example 4 This embodiment provides a vanadium pentoxide composite material, the preparation method of which includes the following steps: Ammonium metavanadate was dissolved in a mixed solvent of deionized water and ethylene glycol at a volume ratio of 1:1, with a solid-liquid ratio of 0.7 g: 60 mL, to obtain a mixed solution. Ammonium chloride was then added, with a mass ratio of 0.7:0.2 between ammonium metavanadate and ammonium chloride. The mixture was magnetically stirred until completely dissolved. The solution was transferred to a high-pressure reactor and reacted at 180 °C for 4 h. After the reaction, the product was dried at 80 °C for 12 h. Finally, under a nitrogen atmosphere, the temperature was increased to 400 °C at a rate of 2 °C / min and held for 3 h to obtain a vanadium pentoxide composite material. SEM analysis revealed that the vanadium pentoxide composite material consists of a core and a coating layer covering the core. The core is a three-dimensional flower-like vanadium pentoxide sphere, which comprises disordered stacked nanosheets and nanoparticles. The coating layer contains nitrogen.

[0043] Comparative Example 1 This comparative example provides a vanadium pentoxide material, the preparation method of which includes the following steps: Ammonium metavanadate was dissolved in a mixed solvent of deionized water and ethylene glycol at a volume ratio of 1:1, with a solid-liquid ratio of 0.7 g: 60 mL to obtain a mixed solution. The solution was transferred to a high-pressure reactor and reacted at 180 °C for 4 h. After the reaction, the product was dried at 80 °C for 12 h. Finally, under a nitrogen atmosphere, the temperature was increased to 400 °C at a rate of 2 °C / min and held for 3 h to obtain vanadium pentoxide material. SEM analysis showed that the vanadium pentoxide composite material includes a core, which is a three-dimensional flower-like vanadium pentoxide sphere. The three-dimensional flower-like vanadium pentoxide sphere includes disordered stacked nanosheets and nanoparticles.

[0044] Comparative Example 2 This comparative example provides a vanadium pentoxide composite material, the preparation method of which includes the following steps: Ammonium metavanadate was dissolved in a mixed solvent of deionized water and ethylene glycol in a volume ratio of 1:1, with a solid-liquid ratio of 0.7 g: 60 mL to obtain a mixed solution. Glucose and ammonium chloride were then added, with a mass ratio of 0.7:0.1:0.1. The mixture was magnetically stirred until completely dissolved. The solution was transferred to a high-pressure reactor and reacted at 150 °C for 6 h. After the reaction, the product was dried at 80 °C for 12 h. Finally, under a nitrogen atmosphere, the temperature was increased to 400 °C at a rate of 2 °C / min and held for 3 h to obtain a vanadium pentoxide composite material. SEM analysis revealed that the vanadium pentoxide composite material consists of a core and a coating layer covering the core. The core is a three-dimensional flower-like vanadium pentoxide sphere, which comprises disordered stacked nanosheets and nanoparticles. The coating layer consists of carbon and nitrogen elements.

[0045] Comparative Example 3 This comparative example provides a vanadium pentoxide composite material, the preparation method of which includes the following steps: Ammonium metavanadate was dissolved in a mixed solvent of deionized water and ethylene glycol in a volume ratio of 1:1, with a solid-liquid ratio of 0.7 g: 60 mL to obtain a mixed solution. Glucose and ammonium chloride were then added, with a mass ratio of 0.7:0.1:0.1. The mixture was magnetically stirred until completely dissolved. The solution was transferred to a high-pressure reactor and reacted at 190 °C for 3 h. After the reaction, the product was dried at 80 °C for 12 h. Finally, under a nitrogen atmosphere, the temperature was increased to 400 °C at a rate of 2 °C / min and held for 3 h to obtain a vanadium pentoxide composite material. SEM analysis revealed that the vanadium pentoxide composite material consists of a core and a coating layer covering the core. The core is a three-dimensional flower-like vanadium pentoxide sphere, which comprises disordered stacked nanosheets and nanoparticles. The coating layer consists of carbon and nitrogen elements.

[0046] Test case The products obtained in the examples and comparative examples, conductive agent acetylene black, binder PVDF, and solvent N-methylpyrrolidone (NMP) were mixed, wherein the mass ratio of the products obtained in the examples and comparative examples, conductive agent acetylene black, and binder PVDF was 90:3:2, and the solid content was 65%, to prepare a positive electrode slurry. Simultaneously, graphite material, binder LA133, conductive agent CNT, and solvent water were mixed, wherein the mass ratio of graphite material, binder LA133, and conductive agent CNT was 90:2:1, and the solid content was 60%, to prepare a negative electrode slurry. The mixture was then coated (single-sided coating surface density 10 mg / cm²). 2 The process involves a series of standard soft-pack battery manufacturing steps, including rolling, slicing, winding, assembly, liquid injection, formation, secondary sealing, and capacity testing, to complete the battery preparation. Test method for charge and discharge capacity: At 25℃, charge the battery to 4.0V at a rate of 0.1C, and obtain the specific capacity of the first charge at 0.1C based on the battery mass; then discharge the battery to 1.5V at a rate of 0.1C, and obtain the specific capacity of the first discharge at 0.1C based on the battery mass. Initial efficiency = (0.1C initial discharge specific capacity / 0.1C initial charge specific capacity) × 100%; Test method for capacity retention rate: At 25℃, charge the battery to 4.0V at a rate of 0.5C, then discharge it to 1.5V at a rate of 0.5C, repeat X times. The capacity retention rate of the Xth cycle = (discharge capacity of the Xth cycle / discharge capacity of the 1st cycle) × 100%, where X = 100, 200, 300, 400 or 500. The test results are shown in Table 1; Table 1

[0047] A comparison of Example 1 and Comparative Examples 1-3 shows that the present invention selects ammonium metavanadate as the precursor raw material for vanadium pentoxide, and conducts a hydrothermal reaction under specific hydrothermal conditions to obtain the precursor. The precursor is then sintered, undergoing phase transformation and structural reconstruction during high-temperature sintering to obtain a vanadium pentoxide composite material. This vanadium pentoxide composite material has a large specific surface area, increasing the contact area between the material and the electrolyte, providing sufficient active sites for ion adsorption and desorption. It also has a short ion diffusion path, effectively reducing resistance during ion migration and accelerating ion transport rates. Furthermore, the addition of a coating agent achieves coating, forming a highly efficient electron conduction network and improving the material's electron conduction efficiency. The synergistic effect of these two factors results in the vanadium pentoxide composite material exhibiting excellent capacity performance and cycle stability.

[0048] A comparison of Examples 1, 3, and 4 shows that when the coating agent is a carbon source and a nitrogen source, the introduction of nitrogen atoms not only significantly improves the electronic conductivity of the carbon layer, but also enhances the adsorption and intercalation capabilities of lithium ions through the defects and active sites (such as pyridine nitrogen) generated by nitrogen, thus achieving a dual improvement in electron and ion transport capabilities.

[0049] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a vanadium pentoxide composite material, characterized in that, The preparation method includes the following steps: mixing ammonium metavanadate, coating agent and solvent and carrying out hydrothermal reaction to obtain a precursor, sintering the precursor to obtain vanadium pentoxide composite material; The conditions for the hydrothermal reaction include: a temperature of 170-185℃ and a time of 2-5 hours.

2. The preparation method according to claim 1, characterized in that, The conditions for the hydrothermal reaction include: a temperature of 175-180℃ and a time of 3-4 hours.

3. The preparation method according to claim 1 or 2, characterized in that, The coating agent includes a carbon source and / or a nitrogen source; Optionally, the mass ratio of ammonium metavanadate to carbon source is (0.1-1):(0.1-0.5); Optionally, the mass ratio of ammonium metavanadate to nitrogen source is (0.1-1):(0.1-0.5).

4. The preparation method according to any one of claims 1-3, characterized in that, The solvent includes water and ethylene glycol; Optionally, the volume ratio of water to ethylene glycol is (1-10):

1.

5. The preparation method according to any one of claims 1-4, characterized in that, The sintering conditions include: heating to 380-450℃ at a rate of 1-3℃ / min and holding for 3-5 hours under nitrogen atmosphere.

6. The preparation method according to any one of claims 1-5, characterized in that, The precursor is also dried before sintering; Optionally, the drying conditions include drying at 80-100°C for 8-12 hours.

7. A vanadium pentoxide composite material according to any one of claims 1-6, characterized in that, The vanadium pentoxide composite material includes a core and a coating layer covering the core; The core is a three-dimensional flower-shaped vanadium pentoxide sphere.

8. The vanadium pentoxide composite material according to claim 7, characterized in that, The three-dimensional flower-shaped vanadium pentoxide spheres comprise nanosheets and nanoparticles; Alternatively, nanosheets and nanoparticles are stacked in a mixture.

9. The vanadium pentoxide composite material according to claim 7 or 8, characterized in that, The material of the coating layer includes carbon. And / or, the material of the coating layer includes nitrogen; Optionally, the coating layer may be made of carbon and nitrogen.

10. A secondary battery, characterized in that, The secondary battery comprises a vanadium pentoxide composite material prepared by any one of claims 1-6 or a vanadium pentoxide composite material prepared by any one of claims 7-9.

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