A vanadium pentoxide / carbon nanocomposite electrode material, a preparation method thereof and an application thereof

Abstract

The present invention relates to a vanadium pentoxide / carbon nanocomposite electrode material, a preparation method and an application thereof, belonging to the technical field of sodium ion battery electrode materials. To solve the problems of low conductivity and poor cycle performance caused by easy fragmentation during cycling when the existing nano-V2O5 material is used as a positive electrode material for lithium ion batteries, the present invention provides a preparation method of a vanadium pentoxide / carbon nanocomposite electrode material, including graphitization treatment of MCMB, functionalization treatment of MCMB, morphology regulation of vanadium oxide and high-temperature calcination of the V x O y / C precursor. Starting from the microscopic structure, the present invention constructs and synthesizes a three-dimensional nanostructured composite electrode material with a specific morphology, enabling the composite electrode material to have a larger chemical specific surface area, providing an effective buffer space for the volume expansion of the material, reducing the transmission paths of sodium ions and electrons, improving the conductivity and structural stability of the electrode material, and thereby enhancing the electrochemical performance of the electrode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium-ion battery electrode materials, and particularly relates to a vanadium pentoxide / carbon nanocomposite electrode material, a preparation method thereof, and an application thereof. Background Art

[0002] Electrochemical energy storage devices include lithium-ion batteries (LIBs), electrochemical capacitors (ECs), metal-oxygen batteries, etc. These rich energy storage systems have shown significant progress and great potential in many application fields such as portable electronic products, hybrid / pure electric vehicles, smart grids, and other rechargeable environmental protection electronic devices. Among them, sodium-ion batteries have attracted the favor of many researchers due to their wide applications in fields such as small mobile electronic devices, electric vehicles, and energy storage power stations. Among transition metals, the theoretical specific capacity of vanadium is 1037 mAh / g, which is 2.7 times that of graphite materials. Vanadium transition metals also have rich valence states and various redox potentials, and various oxides can be prepared through different process optimizations for use as the positive electrode of sodium-ion batteries.

[0003] V2O5 is a transition metal oxide with a well-defined orthorhombic phase, multiple oxidation states (II-V), and a typical layered structure. Its crystal is composed of pyramidal pentahedrons through the ways of sharing points and edges. The good interlayer structure allows ions to reversibly intercalate / deintercalate, increasing the redox reaction between ions and electrolytes. It is a low-cost material suitable for large-scale production. However, bulk V2O5 has poor conductivity, slow reaction kinetics, and is prone to vanadium dissolution, which limits its application. Currently, the bulk crystal structure has been nano-sized and transformed into nanorods, nanowires, nanosheets, nanobelts, and other nanostructures. These nanostructures have better reaction kinetics and shorter diffusion paths, and during the ion intercalation / deintercalation process, they improve the recyclability of the crystal structure with smaller strain. However, these nano-V2O5 materials still have disadvantages such as low conductivity and poor cycle performance due to easy fragmentation during the cycle. Summary of the Invention

[0004] To solve the problems of low conductivity and poor cycle performance due to easy fragmentation during the cycle when existing nano-V2O5 materials are used as the positive electrode material of lithium-ion batteries, the present invention provides a vanadium pentoxide / carbon nanocomposite electrode material, a preparation method thereof, and an application thereof.

[0005] The technical solution of the present invention:

[0006] A preparation method of a vanadium pentoxide / carbon nanocomposite electrode material includes the following steps:

[0007] Step 1: Heat-treat MCMB in a carbonization furnace and a graphite furnace in sequence to obtain graphitized MCMB;

[0008] Step 2: Mix the graphitized MCMB obtained in Step 1 with concentrated sulfuric acid and sodium nitrate and stir to obtain a mixed system I. Add potassium permanganate to the obtained mixed system I in multiple portions under a water bath condition and stir to obtain a mixed system II. Add distilled water to the obtained mixed system II in multiple portions under stirring to obtain a mixed system III. After the obtained mixed system III is cooled to room temperature, add 30% H2O2 thereto until no more bubbles are generated and the solution turns golden yellow. Collect the precipitate product, wash and dry it to obtain the MCMB-based nanocarbon material MCMB-C;

[0009] Step 3: Ultrasonically dissolve ammonium metavanadate in deionized water according to a mass-to-volume ratio of 0.1 - 2.0 g:20 - 200 mL, and adjust the pH value of the obtained ammonium metavanadate aqueous solution to 1 - 5; ultrasonically disperse the MCMB-based nanocarbon material obtained in Step 2 in deionized water to obtain an MCMB-based nanocarbon material system. Mix and stir the obtained MCMB-based nanocarbon material system and the ammonium metavanadate aqueous solution according to a mass ratio of the MCMB-based nanocarbon material to ammonium metavanadate of 1:20 - 1:5, react at 120 - 200 °C for 12 - 24 h, and after the reaction is completed, cool to room temperature, collect the solid product to obtain a V x O y / C precursor powder;

[0010] Step 4: Calcinate the V x O y / C precursor powder at high temperature and then naturally cool it to room temperature to obtain a V2O5 / C solid powder, which is the vanadium pentoxide / carbon nanocomposite electrode material.

[0011] Further, the heating treatment conditions of the carbonization furnace in Step 1 are as follows: under the protection of an inert gas, heat it to 500 - 1000 °C at a heating rate of 5 - 10 °C / min and keep it at a constant temperature for 1 - 5 h; the heating treatment conditions of the graphite furnace are as follows: heat it to 2800 - 3000 °C at a heating rate of 10 - 20 °C / min and keep it at a constant temperature for 1 - 3 h.

[0012] Further, the mass-to-volume ratios of the graphitized MCMB, concentrated sulfuric acid, sodium nitrate, potassium permanganate and distilled water in Step 2 are 1.0 g:30 - 70 mL:1.0 - 5.0 g:3.0 - 8.0 g:60 - 120 mL.

[0013] Further, the concentration of the concentrated sulfuric acid is 90 - 98%, the stirring time of the mixed system I is 10 - 50 min; the temperature of the water bath condition is 30 - 60 °C, and the stirring time of the mixed system II is 12 - 24 h.

[0014] Further, the washing of the precipitate product in Step 2 is to wash it three times with 1 mol / L hydrochloric acid and anhydrous ethanol in sequence, and the drying is to air-dry it at room temperature.

[0015] Further, the reagent used to adjust the pH value of the ammonium metavanadate aqueous solution in step three is ammonia water and an acid solution, and the acid solution is one of nitric acid, oxalic acid, phosphoric acid, formic acid, acetic acid, sulfuric acid or hydrochloric acid.

[0016] Further, the solid product collected in step three is centrifuged under the condition of 8000 r / min and washed several times with water and absolute ethanol in sequence.

[0017] Further, the high-temperature calcination in step four is carried out by heating to 200-500 °C at a heating rate of 5-20 °C / min and holding for 1-5 h.

[0018] A vanadium pentoxide / carbon nanotube composite electrode material prepared by the preparation method of the vanadium pentoxide / carbon nanotube composite electrode material provided by the present invention.

[0019] An application of a vanadium pentoxide / carbon nanotube composite electrode material in the preparation of a sodium-ion battery.

[0020] Advantages of the present invention:

[0021] Starting from the microscopic structure, the present invention constructs and synthesizes a three-dimensional nanostructured composite electrode material with a specific morphology. For the vanadium pentoxide / carbon nanotube composite electrode material provided by the present invention, vanadium pentoxide nanobelts are uniformly anchored on the surface of MCMB-C, enabling the composite electrode material to have a larger chemical specific surface area, providing an effective buffer space for the volume expansion of the material, reducing the transmission paths of sodium ions and electrons, and thus improving the electrochemical performance of the electrode material. Assembling the composite electrode material of the present invention into a sodium-ion half-cell and performing electrochemical tests in a voltage window of 0.01-2.5 V (vs. Na + / Na), when the current density is 40 mA / g, the specific capacity of the electrode is as high as 138 mAh / g; when the current density is further increased, the electrode exhibits a higher capacity retention rate at a small current density, indicating good rate performance. After 100 charge-discharge cycles, the capacity retention rate of the material is still as high as 71.65%, further confirming that nanosizing and compositing vanadium pentoxide can effectively improve problems such as voltage decay and capacity decay faced by vanadium materials, and significantly improve its cycling performance.

[0022] The one-dimensional nanostructure of V2O5 nanosheets provides an effective electron transport path along the one-dimensional direction, and the large specific surface area provides a shorter ion diffusion path. The composite with carbon materials improves the conductivity and structural stability of V2O5 / C. Compared with low-dimensional nanomaterials, the three-dimensional nanostructure material of V2O5 / C not only has a rich reaction interface, which can provide more active sites, but also the three-dimensional framework structure can provide channels for mass transport, effectively avoiding the random agglomeration of active substances while increasing the interface contact, thus maintaining the structural stability of the electrode. Therefore, under the same electrochemical tests, V2O5 / C with three-dimensional or hierarchical structures exhibits better electrochemical performance than low-dimensional electrode materials.

[0023] In the present invention, the composite of V2O5 and mesophase carbon microspheres MCMB helps to improve the overall conductivity of the electrode, increase the specific capacitance, reduce the energy loss during charging / discharging, improve the conductivity and structural stability of the electrode material, overcome the shortcomings of single electrode materials, and is the key to meeting the requirements of fast-charging portable electronic devices, long-life electric vehicles, and environmental protection energy storage devices. Description of the Drawings

[0024] Figure 1 SEM image of the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 1;

[0025] Figure 2 TEM image of the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 1;

[0026] Figure 3 XRD pattern of the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 1;

[0027] Figure 4 Ramam pattern of the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 1;

[0028] Figure 5 Comparison chart of charge-discharge curves of the electrode prepared from the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 1 at different current densities at 25 °C;

[0029] Figure 6 Comparison chart of rate performance of the electrode prepared from the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 1 at different current densities at 25 °C;

[0030] Figure 7 SEM image of the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 2. Detailed Description of the Invention

[0031] The technical solution of the present invention will be further described below in conjunction with embodiments, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be covered by the protection scope of the present invention. For the process equipment or devices not specifically noted in the following embodiments, conventional equipment or devices in the art are used. If not specifically indicated, the raw materials used in the embodiments of the present invention can be obtained commercially; if not specifically indicated, the technical means used in the embodiments of the present invention are conventional means well known to those skilled in the art.

[0032] Example 1

[0033] This example provides a method for preparing a vanadium pentoxide / carbon nanocomposite electrode material, which includes the following steps:

[0034] Step 1: Graphitization treatment of MCMB:

[0035] Put the mesophase carbon microspheres MCMB into a carbonization furnace, and under the protection of an inert gas, heat it to 750 °C at a heating rate of 10 °C / min, keep it at a constant temperature for 1.5 h, and then naturally cool to obtain a carbonized product; after carbonization, heat the MCMB in a graphite furnace to 3000 °C at a heating rate of 10 °C / min, keep it at a constant temperature for 1.5 h, and then cool to obtain graphitized MCMB.

[0036] Step 2: Functionalization treatment of MCMB:

[0037] Add 35 ml of concentrated sulfuric acid with a concentration of 95% to a 250 mL large beaker containing 1.0 g of the graphitized MCMB obtained in Step 1 and 1.2 g of sodium nitrate, stir for 15 min to obtain a mixed system I; place the beaker in a water bath at 30 °C, and add a total of 4.2 g of potassium permanganate to the mixed system I in the beaker in multiple portions, stir for 24 h to obtain a mixed system II; add a total of 75 ml of distilled water to the mixed system II in multiple portions under stirring conditions to obtain a mixed system III; after the mixed system III cools to room temperature, add 30% H2O2 to it until no more bubbles are generated and the solution turns golden yellow. Collect the precipitate product, wash it three times with 1 mol / L hydrochloric acid and ethanol respectively, and dry it at room temperature to obtain the MCMB-based nanocarbon material MCMB-C.

[0038] Step 3: Morphology regulation of vanadium oxide:

[0039] Dissolve 0.7 g of ammonium metavanadate in 30 mL of deionized water at 80 °C by ultrasonic treatment to obtain a light yellow solution. Add ammonia water and nitric acid dropwise to the aqueous solution of ammonium metavanadate to adjust the pH value of the solution to 1.67. Weigh 0.07 g of the MCMB-based nanocarbon material MCMB-C obtained in the second step and disperse it in deionized water by ultrasonic treatment to obtain an MCMB-based nanocarbon material system. Mix and stir the obtained MCMB-based nanocarbon material system with the ammonium metavanadate aqueous solution, pour it into a 100 mL reaction kettle, and react at 180 °C for 15 h. After the reaction is completed, cool it to room temperature, centrifuge the product at 8000 rpm, and wash it three times with water and ethanol respectively to obtain a V x O y / C precursor powder;

[0040] Step 4. High-temperature calcination of the V x O y / C precursor:

[0041] Place the V x O y / C precursor powder obtained in Step 3 in a muffle furnace for high-temperature calcination. Heat it to 350 °C at a heating rate of 10 °C / min and keep it at a constant temperature for 2 h; then let it cool naturally to room temperature, which is the vanadium pentoxide / carbon nanocomposite electrode material.

[0042] Figure 1 and Figure 2 are the SEM image and TEM image of the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 1 respectively; Figure 1 It shows that vanadium pentoxide nanobelts with regular arrangement and distribution are on the surface of the MCMB-based nanocarbon material, and their width is about 300 nm. The vanadium pentoxide nanobelts are anchored on the surface of MCMB, and some nanobelts are adhered together. It can be further observed that the particle size of the composite electrode material is 3 - 5 μm.

[0043] The one-dimensional nanostructure of the V2O5 nanosheets provides an effective electron transport path along the one-dimensional direction, and the large specific surface area provides a shorter ion diffusion path. The composite with the carbon material improves the conductivity and structural stability of V2O5 / C. Compared with low-dimensional nanomaterials, the three-dimensional nanostructure material of V2O5 / C not only has a rich reaction interface, which can provide more active sites, but also the three-dimensional skeleton structure can provide channels for mass transport, effectively avoiding the random agglomeration of active substances while increasing the interface contact, thus maintaining the structural stability of the electrode. Therefore, under the same electrochemical tests, V2O5 / C with a three-dimensional or hierarchical structure exhibits better electrochemical performance than low-dimensional electrode materials.

[0044] Figure 3XRD pattern of the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 1. As can be seen from the figure, 15.4°, 20.3°, 21.7°, 26.1°, 31°, 32.3°, 33.3°, 34.3°, 41.2°, 42°, 45.4°, 47.3°, 51.2° correspond to the (200), (001), (101), (110), (301), (011), (111), (310), (002), (102), (411), (600), (020) crystal planes of vanadium pentoxide respectively, and 26.2° corresponds to the (002) crystal plane of carbon.

[0045] Figure 4 Ramam pattern of the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 1. As can be seen from the figure, 144, 138.8, 480, 280 cm -1 are attributed to the bending vibrations of V-O-V and V=O, and 1350, 1589 are attributed to the D band and G band of carbon.

[0046] To evaluate the electrochemical performance of the electrode at room temperature, V2O5 / C and a sodium metal sheet were assembled into a sodium-ion half-cell, and electrochemical tests were carried out in a voltage window of 0.01 - 2.5 V (vs. Na + / Na). Figure 5 Comparison chart of charge-discharge curves of the electrode prepared from the vanadium pentoxide / carbon nanocomposite electrode material at 25°C and different current densities; Figure 6 Comparison chart of rate performance of the electrode prepared from the vanadium pentoxide / carbon nanocomposite electrode material at 25°C and different current densities.

[0047] Figure 5 It shows that at a current density of 40 mA / g, the specific capacity of the electrode is as high as 138 mAh / g. After 100 cycles, the capacity retention rate is about 72%. Figure 6 It can be clearly seen that when the current density is further increased, the electrode shows a higher capacity retention rate at a small current density, indicating good rate performance. By means of compounding vanadium pentoxide with carbon materials, the vanadium pentoxide cathode material is further modified, and this modification significantly improves its cycling performance. Specifically, after 100 charge-discharge cycles, the capacity retention rate of the material is still as high as 71.65%. It is further confirmed that nanonizing and compounding vanadium pentoxide can effectively improve problems such as voltage decay and capacity decay faced by vanadium materials.

[0048] Example 2

[0049] This example provides a preparation method of a vanadium pentoxide / carbon nanocomposite electrode material, including the following steps:

[0050] Step 1. Graphitization treatment of MCMB:

[0051] Place the mesophase carbon microbeads MCMB in a carbonization furnace. Under the protection of an inert gas, heat it to 650 °C at a heating rate of 10 °C / min, hold for 1.0 h at a constant temperature, and then cool naturally to obtain a carbonized product; after carbonization, heat the MCMB in a graphite furnace to 3000 °C at a heating rate of 10 °C / min, hold for 1.0 h at a constant temperature, and then cool to obtain graphitized MCMB.

[0052] Step 2. Functionalization treatment of MCMB:

[0053] Add 35 ml of concentrated sulfuric acid with a concentration of 95% to a 250 mL large beaker containing 1.0 g of the graphitized MCMB obtained in Step 1 and 1.0 g of sodium nitrate, stir for 15 min to obtain a mixed system I; place the beaker in a water bath at 35 °C, and add a total of 3.8 g of potassium permanganate to the mixed system I in the beaker in multiple portions, stir for 24 h to obtain a mixed system II; add a total of 75 ml of distilled water to the mixed system II in multiple portions under stirring conditions to obtain a mixed system III; after the mixed system III cools to room temperature, add 30% H2O2 to it until no more bubbles are generated and the solution turns golden yellow. Collect the precipitate product, wash it three times with 1 mol / L hydrochloric acid and ethanol respectively, and dry it at room temperature to obtain the MCMB-based nanocarbon material MCMB-C.

[0054] Step 3. Morphology regulation of vanadium oxide:

[0055] Ultrasonically dissolve 0.6 g of ammonium metavanadate in 50 mL of deionized water at 80 °C to obtain a light yellow solution, and adjust the pH value of the ammonium metavanadate aqueous solution to 1.85 by dropping ammonia water and nitric acid respectively. Weigh 0.04 g of the MCMB-based nanocarbon material MCMB-C obtained in Step 2, ultrasonically disperse it in deionized water to obtain an MCMB-based nanocarbon material system. Mix and stir the obtained MCMB-based nanocarbon material system with the ammonium metavanadate aqueous solution, pour it into a 100 mL reaction kettle, and react at 180 °C for 15 h. After the reaction is completed, cool to room temperature, centrifuge the product at 8000 rap / s, and wash it three times with water and ethanol respectively to obtain V x O y / C precursor powder;

[0056] Step 4. High-temperature calcination of the V x O y / C precursor:

[0057] The V x O yThe / C precursor powder was placed in a muffle furnace for high-temperature calcination, heated to 300 °C at a heating rate of 10 °C / min, and kept at a constant temperature for 2 h; then it was naturally cooled to room temperature to obtain the vanadium pentoxide / carbon nanocomposite electrode material.

[0058] Figure 7 Figure 4 is the SEM image of the vanadium pentoxide / carbon nanocomposite electrode material prepared in Example 2. It can be seen from the figure that the nanobelts overlap with each other and are anchored on the surface of the carbon spheres, forming a composite material with a three-dimensional structure. Compared with Example 1, the stacking degree of the vanadium pentoxide nanosheets in this example is greater and they are adhered to each other, increasing the specific surface area of the material and providing more active sites to enhance its electrical properties.

[0059] Example 3

[0060] This example provides a preparation method of a vanadium pentoxide / carbon nanocomposite electrode material, including the following steps:

[0061] Step 1. Graphitization treatment of MCMB:

[0062] The mesocarbon microbeads MCMB were placed in a carbonization furnace and heated to 1000 °C at a heating rate of 10 °C / h under the protection of an inert gas, kept at a constant temperature for 2.0 h, and then naturally cooled to obtain a carbonized product; the carbonized MCMB was heated to 3000 °C at a heating rate of 10 °C / h in a graphite furnace, kept at a constant temperature for 1.0 h, and then cooled to obtain graphitized MCMB.

[0063] Step 2. Functionalization treatment of MCMB:

[0064] 35 ml of concentrated sulfuric acid with a concentration of 95% was added to a 250 mL large beaker containing 1.0 g of the graphitized MCMB obtained in Step 1 and 3.0 g of sodium nitrate, and stirred for 15 min to obtain a mixed system I; the beaker was placed in a water bath at 40 °C, and a total of 6.1 g of potassium permanganate was added to the mixed system I in the beaker in several portions, and stirred for 24 h to obtain a mixed system II; a total of 75 ml of distilled water was added to the mixed system II in several portions under stirring to obtain a mixed system III; after the mixed system III was cooled to room temperature, 30% H2O2 was added to it until no more bubbles were generated and the solution was golden yellow. The precipitate product was collected, washed three times with 1 mol / L hydrochloric acid and ethanol respectively, and dried at room temperature to obtain the MCMB-based nanocarbon material MCMB-C.

[0065] Step 3. Morphology regulation of vanadium oxide:

[0066] Dissolve 0.7 g of ammonium metavanadate ultrasonically in 50 mL of deionized water at 80 °C to obtain a light yellow solution. Add ammonia water and nitric acid dropwise to the aqueous solution of ammonium metavanadate to adjust the pH value of the solution to 2.85. Weigh 0.14 g of the MCMB-based nanocarbon material MCMB-C obtained in the second step and disperse it ultrasonically in deionized water to obtain the MCMB-based nanocarbon material system. Mix and stir the obtained MCMB-based nanocarbon material system with the ammonium metavanadate aqueous solution, pour it into a 100 mL reaction kettle, and react at 180 °C for 15 h. After the reaction is completed, cool it to room temperature, centrifuge the product at 8000 rpm, and wash it three times with water and ethanol respectively to obtain the V x O y / C precursor powder;

[0067] Step 4. High-temperature calcination of the V x O y / C precursor:

[0068] Place the V x O y / C precursor powder obtained in the third step in a muffle furnace for high-temperature calcination. Heat it to 400 °C at a heating rate of 10 °C / h and keep it at a constant temperature for 2 h; then let it cool naturally to room temperature, which is the vanadium pentoxide / carbon nanocomposite electrode material.

Claims

1. A preparation method of a vanadium pentoxide / carbon nanocomposite electrode material, characterized in that, It includes the following steps: Step 1: Heat MCMB successively in a carbonization furnace and a graphite furnace to obtain graphitized MCMB; Step 2: Mix the graphitized MCMB obtained in Step 1 with concentrated sulfuric acid and sodium nitrate and stir to obtain a mixed system I. Add potassium permanganate to the obtained mixed system I in several portions under water bath conditions and stir to obtain a mixed system II. Add distilled water to the obtained mixed system II in several portions under stirring conditions to obtain a mixed system III. After the obtained mixed system III is cooled to room temperature, add 30% H2O2 thereto until no more bubbles are generated and the solution turns golden yellow. Collect the precipitate product, wash and dry it to obtain the MCMB-based nanocarbon material MCMB-C; Step 3: Ultrasonically dissolve ammonium metavanadate in deionized water at a mass-volume ratio of 0.1 - 2.0 g:20 - 200 mL, and adjust the pH value of the obtained ammonium metavanadate aqueous solution to 1 - 5; ultrasonically disperse the MCMB-based nanocarbon material obtained in Step 2 in deionized water to obtain an MCMB-based nanocarbon material system, and mix and stir the obtained MCMB-based nanocarbon material system with the ammonium metavanadate aqueous solution at a mass ratio of MCMB-based nanocarbon material to ammonium metavanadate of 1:20 - 1:5, react at 120 - 200 °C for 12 - 24 h, cool to room temperature after the reaction is completed, collect the solid product, and obtain a V x O y / C precursor powder; Step 4. The V x O y / C precursor powder is calcined at high temperature and then naturally cooled to room temperature to obtain V2O5 / C solid powder, which is the vanadium pentoxide / carbon nanocomposite electrode material.

2. The preparation method of a vanadium pentoxide / carbon nanocomposite electrode material according to claim 1, characterized in that, The heating treatment conditions of the carbonization furnace in Step 1 are as follows: under the protection of an inert gas, heat it at a heating rate of 5 - 10 °C / h to 500 - 1000 °C, and keep it at a constant temperature for 1 - 5 h; the heating treatment conditions of the graphite furnace are as follows: heat it at a heating rate of 10 - 20 °C / h to 2800 - 3000 °C, and keep it at a constant temperature for 1 - 3 h.

3. The preparation method of a vanadium pentoxide / carbon nanocomposite electrode material according to claim 1 or 2, characterized in that, The mass-volume ratio of the graphitized MCMB, concentrated sulfuric acid, sodium nitrate, potassium permanganate and distilled water in Step 2 is 1.0 g: 30 - 70 mL: 1.0 - 5.0 g: 3.0 - 8.0 g: 60 - 120 mL.

4. The preparation method of a vanadium pentoxide / carbon nanocomposite electrode material according to claim 3, characterized in that, The concentration of the concentrated sulfuric acid is 90 - 98%, and the stirring time of the mixed system I is 10 - 50 min; the temperature of the water bath conditions is 30 - 60 °C, and the stirring time of the mixed system II is 12 - 24 h.

5. The preparation method of a vanadium pentoxide / carbon nanocomposite electrode material according to claim 4, characterized in that, The washing of the precipitate product in Step 2 is to wash it three times with 1 mol / L hydrochloric acid and anhydrous ethanol respectively, and the drying is to air-dry it at room temperature.

6. The preparation method of a vanadium pentoxide / carbon nanocomposite electrode material according to claim 5, characterized in that, The reagents used to adjust the pH value of the ammonium metavanadate aqueous solution in Step 3 are ammonia water and an acid solution, and the acid solution is one of nitric acid, oxalic acid, phosphoric acid, formic acid, acetic acid, sulfuric acid or hydrochloric acid.

7. The preparation method of a vanadium pentoxide / carbon nanocomposite electrode material according to claim 6, characterized in that, The collection of the solid product in Step 3 is to centrifuge it at 8000 rap / s and wash it several times with water and anhydrous ethanol in turn.

8. The preparation method of a vanadium pentoxide / carbon nanocomposite electrode material according to claim 7, characterized in that, The high-temperature calcination in Step 4 is to heat it at a heating rate of 5 - 20 °C / min to 200 - 500 °C and keep it at a constant temperature for 1 - 5 h.

9. A vanadium pentoxide / carbon nanocomposite electrode material prepared by the preparation method of the vanadium pentoxide / carbon nanocomposite electrode material according to any one of claims 1 - 8.

10. An application of the vanadium pentoxide / carbon nanocomposite electrode material according to claim 9 in the preparation of a sodium ion battery.

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