A method for controllable preparation of V2O5 nanorods by carbon template

Abstract

The application belongs to the field of functional materials, and particularly relates to a method for controllably preparing V2O5 nanorods by using carbon as a template and application thereof. The V2O5 nanorod material is prepared by adopting the method of carbon material impregnation metavanadate-inert atmosphere calcination-air calcination, and by controlling the types of carbon and the calcination conditions, the controllable preparation of V2O5 nanorods with different sizes and morphologies is realized, and the synthesis method is simple and easy to mass-produce. The material obtained by the application has excellent performance as a lithium ion battery negative electrode material and a lithium-sulfur battery positive electrode carrier material, and is beneficial to the preparation of high-energy-density electrode materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional materials, and particularly relates to a method for controllably preparing V2O5 nanorods by using carbon as a template. BACKGROUND

[0002] Since the twenty-first century, energy crisis has become a common problem faced by all mankind. The depletion of non-renewable energy sources such as fossil fuels has prompted people to continuously develop renewable energy sources such as wind energy, water energy, and solar energy to meet daily production and life. However, these renewable energy sources are intermittent and have problems such as instability, uneven distribution, etc. Therefore, it is crucial to use advanced energy storage systems to effectively store the power generated by renewable energy sources. Lithium secondary batteries have achieved great success in the past two decades due to their high energy density and small size. In particular, lithium batteries have been used as power sources or energy storage systems in some emerging technology fields such as electric vehicles and unmanned aerial vehicles. However, the energy density and capacity of lithium ion batteries are limited by traditional electrode materials and have reached the limit, which cannot meet the needs of people's production and life. Therefore, it is urgent to develop new electrode materials to improve the performance of lithium ion batteries to meet people's needs. In the research process, transition metal oxide (TMO) nanomaterials have attracted widespread attention due to their high specific surface area, short ion diffusion path, and significantly enhanced reaction kinetics.

[0003] Vanadium pentoxide (V2O5) is a transition metal oxide that is easy to synthesize, low in cost, large in capacity, and has unique electrochemical energy storage properties, and is therefore highly concerned in the research and development of new lithium ion battery materials. However, V2O5 needs to be structurally modified to obtain ideal electrode active materials due to its poor electrical conductivity. In recent years, V2O5 with different micro-nano structures has stood out among various transition metal oxide electrode materials. For example, An et al. used NH4VO3 and urea for solvothermal reaction, and utilized ammonium-based thermal decomposition to release ammonia and leave a large number of voids, finally obtaining V2O5 microporous sheets in the shape of a flying dart. The numerous pores on the surface of this flying dart-like electrode material can improve the penetration efficiency of the electrolyte, increase the interface area between the solid electrode and the liquid electrolyte, and make the maximum specific capacity of the battery reach 146 mAh g -1 (J. Mater. Chem. A 2014, 2, 3297). Wang et al. used a reflux method to calcine ammonium metavanadate sol in air to prepare three-dimensionally layered and porous V2O5 microspheres. These porous microspheres are composed of a large number of interlaced nanoparticles with a size of about 200 nm. This porous structure provides a larger surface area, a shorter ion diffusion length, and a larger buffer space for volume expansion / contraction. Experimental results show that this material has good electrochemical performance with a maximum specific capacity of 142 mAh g -1, the capacity attenuation rate is 0.28% after 100 cycles. (J. Colloid Interface Sci. 2014, 418, 74); at the same time, the above method is mainly a liquid phase method, such as a solvothermal method, an electrodeposition method, a sol-gel method, etc., which usually needs to be prepared in an acidic solution such as nitric acid or hydrochloric acid, and the reaction process is dangerous and produces a large amount of harmful waste liquid. The reaction process of preparing vanadium pentoxide nanomaterials by a liquid phase method is complex, and a large amount of expensive surfactant needs to be added, so the above-mentioned preparation method has defects of a relatively complex process, high cost, and a small specific capacity that needs to be further improved. SUMMARY

[0004] The present application provides a method for preparing V2O5 nanorods using carbon as a template and an application, which specifically prepares V2O5 nanorod materials by a method of carbon material impregnation, ammonium metavanadate-inert atmosphere calcination-air calcination, realizes controllable preparation of V2O5 nanorods by controlling the type of carbon and calcination conditions, and has a simple and easy-to-operate preparation method and can realize large-scale production. At the same time, the carbon used in the present application can be a carbon material with a wide source and low cost, and the preparation method is simple and economical. The V2O5 nanorods obtained by the present application can be used as a lithium ion battery negative material and a lithium-sulfur battery positive carrier material, have excellent performance, and are conducive to the preparation of high-energy-density electrode materials.

[0005] The present inventors found that, in addition to the above-mentioned performance, vanadium pentoxide also has strong polar adsorption capacity and catalytic capacity, and can be used as a lithium-sulfur battery positive sulfur carrier material. Vanadium pentoxide micro-nano structure has a high specific surface area, which can provide abundant sulfur loading space. It can more effectively fix sulfur active substances to achieve the purpose of inhibiting the polysulfide shuttle effect, and these sufficient spaces also provide a large number of channels for lithium ion diffusion, thereby ensuring the smooth progress of electrochemical reactions. Therefore, vanadium pentoxide has a good application prospect whether it is used as a lithium ion battery negative material or a lithium-sulfur battery positive sulfur carrier. And by adjusting the micro-nano structure of vanadium pentoxide, its capacity and cycle performance can be better improved.

[0006] The present inventors finally decided to use carbon material as a template to prepare vanadium pentoxide nanorods, and the specific preparation steps are as follows:

[0007] A method for controllably preparing V2O5 nanorods using carbon as a template, and the specific steps are as follows:

[0008] (1) carbon material is impregnated into an ammonium metavanadate solution, then suction filtration is performed to separate out the carbon material loaded with ammonium metavanadate, and drying is performed for 12-24h;

[0009] Preferably, a certain mass of ammonium metavanadate is added to 50 mL of distilled water, ultrasonically dissolved, and a molar concentration of the obtained ammonium metavanadate solution is 0.1-0.3 mol / L -1 ; a carbon material is taken according to a mass ratio of 0.1-0.3 of the carbon material to ammonium metavanadate, and is placed in the above-mentioned ammonium metavanadate solution;

[0010] Further, the carbon material is taken, placed in the above-mentioned ammonium metavanadate solution, ultrasonically treated for 5 min, and immersed for 2 h, and the immersed carbon material is separated by suction filtration and dried at 60 ℃ for 24 h;

[0011] (2) The immersed carbon material is placed in a tube furnace in an argon atmosphere and calcined;

[0012] Preferably, the temperature is raised at a rate of 3.5 ℃ / min -1 to 400 ℃, kept for 4 h, then raised at a rate of 5 ℃ / min -1 to 850 ℃, and kept for 2 h.

[0013] (3) The material obtained in (2) is washed by suction filtration with distilled water and ethanol, and dried;

[0014] (4) The material obtained in (3) is calcined in a muffle furnace for 1-3 h, and V2O5 nanorods are obtained;

[0015] Preferably, the calcination temperature is 500-550 ℃, and the temperature raising rate is 2-10 ℃ / min -1 .

[0016] The carbon material is a fibrous or sheet-like carbon material selected from one or more of graphene, graphite, carbon cloth, carbon paper, carbon fiber, and biomass carbon.

[0017] Further, the biomass carbon is a carbon material obtained by calcining biomass, and the biomass includes but is not limited to agricultural and forestry waste such as straw, willow catkins, cotton, coconut shell, flax, and poplar catkins; and the preparation method includes the following specific steps:

[0018] The biomass is carbonized in a tube furnace in an argon atmosphere, and biomass carbon is obtained; wherein the temperature raising rate is 2-5 ℃ / min -1 , the holding temperature is 400-550 ℃, and the holding time is 2-6 h.

[0019] According to the different types of carbon materials, the calcination time and temperature are adjusted to obtain different sizes and morphologies, and the details are as follows:

[0020] When the carbon material used is a one-dimensional or two-dimensional carbon material with a nanometer size such as graphene, carbon cloth, and carbon fiber, the calcination time is 1-3 h, the calcination temperature is 500 ℃, and V2O5 nanorods with a smaller size, a diameter of about 200-500 nm, a length of 0.5 μm-5 μm, and an aspect ratio of about 2-20 are obtained.

[0021] When the carbon material used is a biomass carbon or the like, which is a carbon material of micron size with a large size in one or two dimensions, the calcination time is 1-3h, and the calcination temperature is 500-550℃, the V2O5 nanorods obtained are large in size, with an average diameter of about 400-500nm, a length of 2-5um, and an aspect ratio of about 4-13.

[0022] The specific mechanism of the above preparation method is as follows:

[0023] When calcination is performed in air, the degradation of the carbon material and the growth of the V2O5 nanoparticles occur simultaneously. With the increase of the temperature, the carbon material is oxidized into CO2 and rapidly volatilized, while V2O3 is oxidized into V2O5 nanoparticles on the surface of the carbon material. When the calcination temperature reaches a certain temperature, V2O3 is oxidized into V2O5, and V2O5 begins to crystallize and agglomerate and gradually grows into a rod shape. If the calcination temperature is continuously increased or the calcination time is prolonged, the nanorods will further grow into large-sized nanosheets or block materials. In addition, due to the different sizes and specific surface areas of different carbon materials, the size of the loaded vanadium source will be different, and when a large-sized (small specific surface area) carbon material is used, large-sized V2O5 nanorods can be generated, while when a small-sized (large specific surface area) carbon material is used, small-sized V2O5 nanorods are usually generated. Therefore, by controlling the calcination temperature and time, the morphology of the prepared V2O5 can be controlled to be a nanorod, and by changing the size of the carbon material, the size of the obtained nanorod can be controlled. Therefore, the method provided by the present application can realize the controllable preparation of V2O5 nanorods.

[0024] The V2O5 nanorods prepared by the above method can be applied in the preparation of lithium ion batteries, zinc ion batteries and sodium ion batteries, and can be used as a negative electrode material of a lithium ion battery.

[0025] The V2O5 nanorods prepared by the above method can be applied in the preparation of lithium-sulfur batteries, and can be used as a positive electrode carrier of a lithium-sulfur battery.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] (1) The present application uses a simple and easy method to prepare V2O5 nanorods, which is simple, efficient and low in cost compared with the current solvothermal preparation method of V2O5;

[0028] (2) The carbon source used in the present application is widely available, and the use of biomass carbon can realize the transformation of agricultural waste into treasure;

[0029] (3) The present application realizes the controllable preparation of V2O5 nanorods by controlling the type of carbon and the calcination conditions, and the synthesis method is simple and easy to mass-produce.

[0030] (4) The V2O5 nanorod as the negative electrode material of the lithium ion battery is beneficial to promote ion transmission and improve electrochemical performance.

[0031] (5) The V2O5 nanorod used as the positive electrode carrier of the lithium-sulfur battery can provide a large number of polar adsorption sites for lithium polysulfide due to its large specific surface area and strong polarity, effectively slows down the shuttle effect, is beneficial to promote charge transfer in the electrochemical conversion reaction of sulfur, catalyzes the efficient and reversible performance of the sulfur charge-discharge reaction, and further improves the electrochemical performance of the sulfur electrode. Meanwhile, the unique nanostructure can realize uniform compounding with sulfur, thereby improving the electrochemical performance of the sulfur positive electrode.

[0032] When the V2O5 nanorod prepared by using the poplar biomass carbon as a template is used as an electrode material and assembled into a battery with metal lithium, the specific capacity can still be maintained at 336 mAh g-1 after 100 cycles. -1 When the V2O5 nanorod prepared by using the poplar biomass carbon as a template is used as a carrier material and compounded with sulfur, the specific capacity of the prepared sulfur-based composite material can reach 1333 mAh g-1 in the first cycle. -1 . BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The XRD image of the V2O3@poplar biomass carbon composite material precursor prepared in Example 1;

[0034] Figure 2 The XRD image of the V2O5 nanorod prepared in Example 1;

[0035] Figure 3 The SEM image of the V2O5 nanorod prepared in Example 1;

[0036] Figure 4 The first cycle charge-discharge curve of the electrode prepared from the V2O5 nanorod prepared in Example 1;

[0037] Figure 5 The cycle performance curve of the electrode prepared from the V2O5 nanorod prepared in Example 1;

[0038] Figure 6 The first cycle charge-discharge curve of the sulfur positive electrode prepared by using the V2O5 nanorod prepared in Example 1 as a carrier of the lithium-sulfur battery;

[0039] Figure 7 The SEM image of the V2O5 nanorod prepared in Example 2;

[0040] Figure 8 The first cycle charge-discharge curve of the electrode prepared from the V2O5 nanorod prepared in Example 2;

[0041] Figure 9 The first-cycle charge-discharge curve of the sulfur cathode prepared using V2O5 nanorods as a lithium-sulfur battery carrier in Example 2.

[0042] Figure 10 SEM image of the V2O5 nanorods prepared in Example 3;

[0043] Figure 11 The first-cycle charge-discharge curve of the sulfur cathode prepared using V2O5 nanorods prepared in Example 3 as a lithium-sulfur battery carrier.

[0044] Figure 12 The first-cycle charge-discharge curve of the electrode prepared from the V2O5 nanorods prepared in Example 3;

[0045] Figure 13 SEM image of the V2O5 nanosheets prepared in Comparative Example 1;

[0046] Figure 14 The image shows a SEM image of V2O5 prepared in Comparative Example 2. Detailed Implementation

[0047] The invention will be further illustrated below with specific implementation examples. These examples are only intended to provide a complete and clear explanation of the invention, and are not intended to represent all possible implementations. All other implementations created based on this invention are within the scope of protection of this invention. Materials such as Super P, PVdF, and NMP used in the following embodiments are conventional reagents in the art.

[0048] Example 1

[0049] A method for preparing V2O5 nanorods using poplar catkin biomass carbon as a template is described below:

[0050] Collect poplar fluff from Canadian poplar trees at 5℃ for 1 minute. -1 The temperature was raised to 400℃ and kept at that temperature for 6 hours to obtain poplar catkin biomass carbon.

[0051] Prepare 50 mL of 0.2 mol L... -1 Ammonium metavanadate solution: Add 1.17g of ammonium molybdate to 50mL of distilled water and dissolve by sonication. Place 0.3g of poplar catkin biomass carbon in the ammonium metavanadate solution and sonicate for 5min. Remove and soak for 2h. Filter to obtain the soaked poplar catkin biomass carbon and dry at 60℃.

[0052] The impregnated poplar catkin biomass char was placed in a tube furnace and heated at 3.5℃ for 1 minute in an argon atmosphere. -1 Heat to 400℃ and hold for 4 hours, then reduce temperature by 5℃ / min. -1heated to 850℃ for 2h, and the obtained sample was taken out after cooling to room temperature, washed with distilled water and ethanol for three times, and dried at 60℃ to obtain the precursor V2O3@ biomass carbon composite material for preparing V2O5 nanorods.

[0053] The precursor obtained above was placed in a muffle furnace and heated at a rate of 5℃ / min -1 to 500℃ for 1h to obtain V2O5 nanorod material. The structure, morphology and electrochemical performance of the material were characterized.

[0054] Figure 1 The XRD image of V2O3@ biomass carbon composite material prepared in Example 1. As can be seen from the figure, the obtained XRD spectrum has sharp peak shape, and corresponds to the standard card PDF #76-1043 of V2O3. At the same time, the peak near 26° is the diffraction peak of biomass carbon, indicating that V2O3@ biomass carbon composite material is successfully obtained.

[0055] Figure 2 The XRD image of V2O5 nanorod prepared in Example 1. As can be seen from the figure, the obtained XRD spectrum has sharp peak shape, and corresponds to the standard card PDF #41-1426 of V2O5, indicating that V2O5 nanorod is successfully obtained.

[0056] Figure 3 The SEM image of V2O5 nanorod prepared in Example 1. As can be seen from the figure, the length of V2O5 nanorod is about 5μm, the diameter is about 200nm, and the aspect ratio is 1:25.

[0057] The V2O5 nanorod material prepared above was made into an electrode sheet according to the following method, and a half-cell was assembled with metal lithium as the counter electrode to test its electrochemical performance. The specific method is as follows:

[0058] 0.8g of the V2O5 nanorod prepared above, 0.1g of conductive carbon black (Super P), and 0.1g of polyvinylidene fluoride (PVdF) were weighed into a flat weighing bottle, mixed uniformly, then 2mL of N-methyl pyrrolidone (NMP) was added, stirred for 6h to obtain a positive electrode slurry with suitable viscosity; then the slurry was uniformly coated on a copper foil using a coating machine, dried in a 60℃ oven for 12h for standby; then the dried positive electrode sheet was cut into a 10mm diameter circle, and a 2032 button cell was assembled in an argon-filled glove box, and after assembly, the cell was left to stand for 4h, then activated on a battery test system at 0.1C for two weeks, and then tested at 0.2C, 0.01-3V (vs. Li + / Li discharge) voltage range.

[0059] obtained as Figure 4Battery charge / discharge performance chart for the first week; first-week discharge specific capacity is 688mAh g. -1 ; Figure 5 The battery cycle performance graph shows that after 100 cycles, the discharge specific capacity is 331 mAh g. -1 .

[0060] Using the above-mentioned V2O5 material as a carrier, an S / V2O5 sulfur-based composite cathode material was prepared by a melt method. The specific preparation process is as follows:

[0061] 0.8 g of elemental sulfur was mixed with 0.2 g of the V2O5 nanorods prepared above, and ground in an agate mortar for 30 min. Then, the mixture was placed in a crucible wrapped with tin foil and kept at 155 °C for 12 h. After the heating was completed and the mixture was allowed to return to room temperature, the product was ground again in an agate mortar for 20 min to finally obtain sulfur-based composite cathode material S / V2O5 with V2O5 as the carrier and sulfur content of 80 wt%.

[0062] The obtained S / V2O5 composite cathode material was fabricated into an electrode sheet according to the following method, and then a battery was assembled and tested. The specific experimental steps are as follows:

[0063] Weigh 0.28 g of the S / V₂O₅ positive electrode composite material prepared above, 0.08 g of conductive carbon black (Super P), and 0.04 g of polyvinylidene fluoride (PVdF), place them in a flat weighing bottle, mix well, and then add 2.6 mL of the mixture. N-methylpyrrolidone (NMP) was stirred for 6 hours to obtain a positive electrode slurry with suitable viscosity. Then, the slurry was uniformly coated onto carbon paper (Toray carbon paper, model: TGP-H-060 hydrophilic type) using a coating machine, with a coating amount of 0.2g. The slurry was then dried in a 60℃ oven for 12 hours. The dried positive electrode was then cut into 10mm diameter discs, with each disc containing approximately 1-2mg of sulfur. The discs were assembled into coin cells in an argon-filled glove box, with an electrolyte concentration of 30μL / mg (based on the aforementioned sulfur mass). After assembly, the cells were allowed to stand for 24 hours. Then, they were activated at 0.03C for one week and 0.05C for one week on a battery testing system. Subsequently, the cells were tested using a charge-discharge program with a voltage range of 0.1C and 1.7-2.8V.

[0064] Get as Figure 6 The first-cycle charge-discharge curve of the sulfur cathode prepared using V2O5 nanorods as a lithium-sulfur battery carrier is shown, with a first-cycle discharge specific capacity of 1333 mAh g. -1 .

[0065] Example 2

[0066] A method for preparing V2O5 nanorod materials using carbon cloth composed of carbon fibers as a template is described below:

[0067] The specific impregnation steps and reagent dosages are the same as in Example 1.

[0068] Carbon cloth impregnated with ammonium metavanadate was placed in a muffle furnace and heated to 5°C for 5 minutes. -1 The V₂O₅ nanorod material was obtained by heating to 500℃ and holding for 2 hours. The morphology and electrochemical properties of the material were then characterized.

[0069] Figure 7 The image shows a SEM image of the V2O5 nanorod material prepared in Example 2. As can be seen from the image, the prepared V2O5 nanomaterial is rod-shaped with a diameter of 50-100 nm and a length of about 100-200 nm, with an aspect ratio of 1:1-1:4. It can also be seen that it grows along the carbon cloth fiber.

[0070] The V2O5 nanorod material prepared above was used to fabricate an electrode sheet, and a half-cell was assembled with lithium metal as the counter electrode to test its electrochemical performance. The specific method is as described in Example 1.

[0071] Using the above-mentioned V2O5 material as a carrier, an S / V2O5 sulfur-based composite cathode material was prepared by a melting method, and then fabricated into an electrode sheet. The battery was then assembled and tested, and the specific experimental steps are as described in Example 1.

[0072] Get as Figure 8 The graph shows the first-week charge-discharge performance of the V2O5 nanorod electrode sheet and the lithium-ion battery. The first-week discharge specific capacity is 711 mAh g. -1 .like Figure 9 The graph shows the first-week charge-discharge performance of the lithium-sulfur battery, indicating a first-week discharge specific capacity of 1113 mAh g. -1 .

[0073] Example 3

[0074] A method for preparing V2O5 nanorod materials using graphene as a template is described below:

[0075] The specific impregnation steps and reagent dosages are the same as in Example 1.

[0076] Graphene impregnated with ammonium metavanadate was placed in a muffle furnace and heated to 5°C for 5 minutes. -1 The V₂O₅ nanorod material was obtained by heating to 500℃ and holding for 2 hours. The morphology and electrochemical properties of the material were then characterized.

[0077] Figure 10 The image shows a SEM image of the V2O5 nanorod material prepared in Example 3. As can be seen from the image, the prepared V2O5 nanomaterial is in the shape of a short rod, with a diameter of 50nm-100nm and a length of about 1μm, and an aspect ratio of 1:10-20.

[0078] The V2O5 nanorod material prepared above was used to fabricate an electrode sheet, and a half-cell was assembled with lithium metal as the counter electrode to test its electrochemical performance. The specific method is as described in Example 1.

[0079] Using the above-mentioned V2O5 material as a carrier, an S / V2O5 sulfur-based composite cathode material was prepared by a melting method, and then fabricated into an electrode sheet. The battery was then assembled and tested, and the specific experimental steps are as described in Example 1.

[0080] Get as Figure 11 The graph shows the first-week charge-discharge performance of the lithium-sulfur battery, indicating a first-week discharge specific capacity of 1226 mAh g. -1 ;like Figure 12 The graph shows the first-week charge-discharge performance of the V2O5 nanorod electrode sheet and the lithium-ion battery. The first-week discharge specific capacity is 620 mAh g. -1 .

[0081] Comparative Example 1

[0082] V₂O₅ nanosheets were prepared using biomass carbon as a template through temperature control. The specific preparation process is as follows:

[0083] Collect poplar fluff from Canadian poplar trees at 5℃ for 1 minute. -1 The temperature was raised to 400℃ and kept at that temperature for 6 hours under an argon atmosphere to obtain poplar catkin biomass carbon.

[0084] Prepare 50 mL of 0.2 mol L... -1 Ammonium metavanadate solution: Add 1.17 g of ammonium metavanadate to 50 mL of distilled water and dissolve by sonication. Place 0.3 g of poplar catkin biomass carbon in the ammonium metavanadate solution and sonicate for 5 min. Remove and soak for 2 h. Filter to obtain the soaked poplar catkin biomass carbon, and dry at 60℃. Place the soaked poplar catkin biomass carbon in a tube furnace and heat at 3.5℃ for 1 min under an argon atmosphere. -1 Heat to 400℃ and hold for 4 hours, then reduce temperature by 5℃ / min. -1 The temperature was raised to 850℃ and held for 2 hours. After cooling to room temperature, the obtained sample was removed, washed three times with distilled water and ethanol respectively, and dried at 60℃ to obtain the precursor for preparing V2O5 nanorods - V2O3@poplar catkin biomass carbon composite material. The poplar catkin biomass carbon precursor was placed in a muffle furnace and heated at 5℃ for 5 minutes. -1 The V2O5 nanosheet material is obtained by heating to 600℃ and holding for 1 hour.

[0085] Figure 13The image shows a SEM image of V₂O₅ prepared at 600°C for Comparative Example 1. As can be seen from the image, the V₂O₅ is in the form of nanosheets, with a width of over 400 nm and a thickness of approximately 100 nm. Using the above V₂O₅ nanosheets as a carrier, a sulfur-based S / V₂O₅ composite cathode material was prepared by a melt method, fabricated into electrode sheets, and assembled into a battery for testing. Specific experimental steps are as described in Example 1. The resulting sulfur-based composite material had a first-cycle discharge specific capacity of 1002 mAh g⁻¹. -1 .

[0086] Comparative Example 2

[0087] Blocky V2O5 was prepared using biomass carbon as a template through temperature control. The specific preparation process is as follows:

[0088] Collect poplar fluff from Canadian poplar trees at 5℃ for 1 minute. -1 The temperature was raised to 400℃ and kept at that temperature for 6 hours under an argon atmosphere to obtain poplar catkin biomass carbon.

[0089] Prepare 50 mL of 0.2 mol L... -1 Ammonium metavanadate solution: Add 1.17 g of ammonium metavanadate to 50 mL of distilled water and dissolve by sonication. Place 0.3 g of poplar catkin biomass carbon in the ammonium metavanadate solution and sonicate for 5 min. Remove and soak for 2 h. Filter to obtain the soaked poplar catkin biomass carbon, and dry at 60℃. Place the soaked poplar catkin biomass carbon in a tube furnace and heat at 3.5℃ for 1 min under an argon atmosphere. -1 Heat to 400℃ and hold for 4 hours, then reduce temperature by 5℃ / min. -1 The temperature was raised to 850℃ and held for 2 hours. After cooling to room temperature, the obtained sample was removed, washed three times with distilled water and ethanol respectively, and dried at 60℃ to obtain the precursor for preparing V2O5 nanorods - V2O3@poplar catkin biomass carbon composite material. The poplar catkin biomass carbon precursor was placed in a muffle furnace and heated at 5℃ for 5 minutes. -1 Heating to 700℃ and holding for 1 hour yields V2O5 block material.

[0090] Figure 14 The image shows a SEM image of V₂O₅ prepared at 700°C for Comparative Example 2. As can be seen from the image, the V₂O₅ is blocky, approximately 2 μm wide and 1 μm thick. Using the above blocky V₂O₅ material as a carrier, an S / V₂O₅ sulfur-based composite cathode material was prepared via a melt method, fabricated into electrode sheets, and then assembled into a battery for testing. Specific experimental steps are as described in Example 1. The first-cycle discharge specific capacity of the obtained blocky V₂O₅ material was 590 mAh g⁻¹. -1 The obtained sulfur-based composite material has a first-cycle discharge specific capacity of 988 mAh g. -1 .

[0091] It can be seen from Comparative Examples 1 and 2 that when the calcination temperature is above 600 degrees, the morphology of the V2O5 nanomaterials changes obviously, from V2O5 nanorods to V2O5 nanosheets and V2O5 bulk materials. This shows that the calcination temperature has a great influence on the size and morphology control of V2O5. At the same time, the obtained nanorods are more conducive to the deintercalation of lithium ions than the nanosheets and bulk materials, and have a larger specific surface area, which can more effectively adsorb lithium polysulfides, and therefore, as electrode materials or carrier materials, are more conducive to obtaining secondary batteries with excellent performance.

[0092] At the same time, as can be seen from the above examples and comparative examples, by changing the type of carbon material and simultaneously controlling the calcination temperature and time, V2O5 nanorods with different sizes and morphologies can be obtained. As electrode materials or carrier materials, they can obtain high specific energy batteries.

[0093] The technical features of the above examples can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above examples are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present disclosure. The above examples can be used to help understand the principles and methods of the present application. However, the above examples are not unique and should not be understood as limiting the present application. At the same time, for those skilled in the art, according to the principles and methods of the present application, specific embodiments and application ranges can be flexibly changed.

Claims

1. A method for controllably preparing V₂O₅ nanorods using carbon as a template, characterized in that, The specific steps are as follows: (1) The carbon material is impregnated in an ammonium metavanadate solution, then filtered to separate the carbon material loaded with ammonium metavanadate, and dried for 12-24 h. The mass ratio of carbon material to ammonium metavanadate is 0.1-0.3; the molar concentration of the ammonium metavanadate solution is 0.1-0.3 mol / L; the carbon material is fibrous or sheet-like and is selected from one or more of graphene, graphite, carbon cloth, carbon paper, and biomass carbon. (2) The impregnated carbon material is placed in a tube furnace under an argon atmosphere for calcination; specifically, the temperature is increased to 400℃ at 3.5℃ / min and held for 4 h, and then increased to 850℃ at 5℃ / min and held for 2 h. (3) Wash the material obtained in (2) with distilled water and ethanol, and then dry it; (4) Calcine the material in (3) in a muffle furnace for 1-3 h to obtain V2O5 nanorods; When the carbon material used is graphene or carbon cloth, the calcination time is 1-3 h, and the calcination temperature is 500 ℃, the obtained V2O5 nanorods have a diameter of 200-500 nm, a length of 0.5μm-5μm, and an aspect ratio of 2-20. When the carbon material used is biomass carbon, the calcination time is 1-3 h, and the calcination temperature is 500-550 ℃, the average diameter of the obtained V2O5 nanorods is 400-500 nm, the length is 2-5 μm, and the aspect ratio is 4-13.

2. The method for controllably preparing V₂O₅ nanorods using carbon as a template according to claim 1, characterized in that, In step (1), the carbon material is placed in the above ammonium metavanadate solution and sonicated for 5 min, then impregnated for 2 h. The impregnated carbon material is then separated by filtration and dried at 60 ℃ for 24 h.

3. The method for controllably preparing V₂O₅ nanorods using carbon as a template according to claim 1, characterized in that, The biomass carbon mentioned in step (1) is a carbon material obtained by calcining biomass. Biomass includes, but is not limited to, one or more of straw, willow catkins, cotton, coconut shells, flax, and poplar catkins. The specific steps of its preparation method are as follows: Biomass is carbonized in a tube furnace under an argon atmosphere to obtain biomass carbon; wherein the heating rate is 2-5℃ / min, the holding temperature is 400-550℃, and the holding time is 2-6 h.

4. The method for controllably preparing V₂O₅ nanorods using carbon as a template according to claim 1, characterized in that, In step (4), the calcination temperature is 500-550 ℃ and the heating rate is 2-10℃ / min.

5. The application of V2O5 nanorods prepared by the method of claim 1 in the preparation of lithium-ion batteries, zinc-ion batteries and sodium-ion batteries.

6. The application of V2O5 nanorods prepared by the method of claim 1 in the preparation of lithium-sulfur batteries.

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