A V2O3 / C@Fe x Mn y O z Negative electrode composite materials, their preparation methods and applications
By preparing V2O3/C@FexMnyOz anode composite material, the problem of unsatisfactory electrochemical performance of activated carbon electrodes was solved, achieving high conductivity and dispersibility, and improving the electrochemical performance of supercapacitors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU UNIV
- Filing Date
- 2023-03-31
- Publication Date
- 2026-05-12
AI Technical Summary
The electrochemical performance of activated carbon electrodes, the existing anode material for supercapacitors, is not ideal, which limits the development of asymmetric supercapacitors. Iron oxides also have poor conductivity and dispersibility.
A V2O3/C@FexMnyOz anode composite material was prepared by mixing ammonium metavanadate and activated carbon and sintering at high temperature to form a V2O3/C substrate. Combined with hydrothermal and low-temperature oxidation methods, a V2O3/C@FexMnyOz material with a mesoporous structure was prepared, which improved its conductivity and dispersibility.
V2O3/C@FexMnyOz materials exhibit a large specific surface area, good cycling stability, high specific capacitance, low ion diffusion impedance, abundant active sites, and excellent electrochemical performance.
Smart Images
Figure CN116544037B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of negative electrode material preparation and supercapacitor technology, specifically relating to a V2O3 / C@Fe... x Mn y O z Negative electrode composite materials, their preparation methods, and applications. Background Technology
[0002] With the rapid development of science and technology and the intensification of urbanization and industrialization, the contradiction between energy issues and environmental pollution has gradually become apparent. To gradually reduce dependence on traditional non-renewable resources, promoting the development of green, environmentally friendly, and renewable clean energy is a crucial issue that industry urgently needs to address. Supercapacitors, as an emerging energy storage device, possess advantages such as high energy density, excellent power density, good cycle stability, and fast charging and discharging, showing great development potential and application value in rail transportation, communications, smart grids, electrical sensors, and medical equipment. Supercapacitors are a promising alternative to traditional batteries. In some electrochemical performance aspects, such as charge / discharge speed, cycle life, and power density, supercapacitors have advantages over traditional batteries.
[0003] Currently, activated carbon is the most common anode material for supercapacitors. However, the electrochemical performance of activated carbon electrodes is not ideal, which limits the development of asymmetric supercapacitors to some extent. Iron oxides are a low-cost anode active material with a large theoretical capacitance. Like other metal oxides, however, their conductivity and dispersibility are relatively poor. Therefore, improving the conductivity and dispersibility of iron oxides is an urgent problem to be solved. Thus, there is a need to provide a supercapacitor anode material that can improve the conductivity and dispersibility of iron oxides. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a V2O3 / C@Fe x Mn y O z Negative electrode composite material, its preparation method and application; the V2O3 / C@Fe x Mn y O z The negative electrode composite material is a blocky structure consisting of countless small spheres, namely V2O3 / C@Fe. x Mn y O z The negative electrode composite material has a large number of mesoporous structures with an average pore size of 5.2–5.7 nm; the V2O3 / C@Fe x Mn y O zElectrode materials have advantages such as good specific capacitance, large specific surface area, good cycle stability, low ion diffusion impedance, and abundant active sites, making them well-suited for use as anode materials in supercapacitors.
[0005] This invention first provides a V2O3 / C@Fe x Mn y O z The negative electrode composite material, namely V2O3 / C@Fe x Mn y O z The negative electrode composite material is a blocky structure consisting of countless small spheres, namely V2O3 / C@Fe. x Mn y O z The negative electrode composite material has a mesoporous structure with an average pore size of 5.2–5.7 nm, and the x:y:z ratio is 8.25:2.76:21.22.
[0006] The present invention also provides the above-mentioned V2O3 / C@Fe x Mn y O z The preparation method of the negative electrode composite material specifically includes the following steps:
[0007] (1) Preparation of precursor V2O3 / C:
[0008] Ammonium metavanadate and activated carbon powder were stirred evenly and then calcined at high temperature to obtain the precursor V2O3 / C.
[0009] (2) Preparation of V2O3 / C@FeMn-LDH:
[0010] Disperse V2O3 / C evenly in water and record as solution 1; dissolve ferric nitrate nonahydrate and manganese acetate tetrahydrate in water and stir thoroughly to dissolve, then record as solution 2; dissolve urea in water and stir thoroughly to dissolve, then record as solution 3.
[0011] Solution 1 was added to solution 2 and stirred until homogeneous. Then solution 3 was added and stirred until homogeneous to obtain a mixed solution. The mixed solution was subjected to hydrothermal reaction. After the reaction was completed, the solution was centrifuged, washed, and dried to obtain V2O3 / C@FeMn-LDH.
[0012] (3) V2O3 / C@Fe x Mn y O z Preparation of negative electrode composite materials:
[0013] V2O3 / C@FeMn-LDH was oxidized at low temperature (280–320 °C) for 100–150 min to obtain V2O3 / C@Fe x Mny O z A negative electrode composite material, wherein x:y:z = 8.25:2.76:21.22.
[0014] Preferably, in step (1), the mass ratio of ammonium metavanadate to activated carbon powder is 4:1 to 3:1.
[0015] Preferably, in step (1), the high-temperature calcination is performed at 750–850°C for 100–150 min.
[0016] Preferably, in step (2), the mass ratio of V2O3 / C, ferric nitrate nonahydrate, manganese acetate tetrahydrate and urea is 60-80 mg: 400-450 mg: 240-260 mg: 180-240 mg.
[0017] Preferably, in step (2), the hydrothermal reaction is carried out at 120-140°C for 9-11 hours.
[0018] The present invention also provides the above-mentioned V2O3 / C@Fe x Mn y O z Application of negative electrode composite materials as negative electrode materials for supercapacitors.
[0019] Preferably, the application is as follows:
[0020] Two pieces of nickel foam were soaked in hydrochloric acid, and after soaking, they were washed and dried to obtain the treated nickel foam.
[0021] V2O3 / C@Fe x Mn y O z Acetylene black, PTFE, and ethanol were mixed and ultrasonically dispersed. The uniformly dispersed mixture was then dropped onto two pieces of treated nickel foam, vacuum dried, and then pressed into thin sheets using a tablet press to obtain the negative electrode V2O3 / C@Fe. x Mn y O z electrode.
[0022] Preferably, the concentration of the hydrochloric acid is 2–4 mol / L;
[0023] The V2O3 / C@Fe x Mn y O z The mass ratio of acetylene black to PTFE is 7.5–8.5:0.9–1.1:0.9–1.1.
[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0025] This invention first involves calcining ammonium metavanadate and activated carbon to create a rough V₂O₃ layer on the smooth activated carbon surface. Simultaneously, the incorporation of carbon imparts electrical conductivity to the V₂O₃ / C composite material. Then, using V₂O₃ / C as a substrate, V₂O₃ / C@Fe is prepared via hydrothermal and low-temperature oxidation methods. x Mn y O z Negative electrode composite material. The V2O3 / C@Fe x Mn y O z The large specific surface area of the negative electrode composite material allows the active material to come into contact with more active sites, providing transport channels for electrons and electrolytes, thereby improving the electrochemical performance of the material.
[0026] When the current density is 1 A / g, V2O3 / C@Fe x Mn y O z The specific capacitance of the negative electrode composite material is 1261.3 F / g, which is far higher than that of ordinary activated carbon electrodes. Furthermore, the V₂O₃ / C@Fe... x Mn y O z The negative electrode composite material retains 89.13% of its initial capacitance after 5000 cycles at a current density of 4A / g, demonstrating good cycle stability.
[0027] The V2O3 / C@Fe of this invention x Mn y O z The preparation method of negative electrode composite material is simple, easy to operate, and uses inexpensive materials with low preparation cost, making it very valuable as a negative electrode material for supercapacitors. Attached Figure Description
[0028] Figure 1 Scanning electron micrographs of V2O3 / C (a) and V2O3 / C@Fe x Mn y O z Scanning electron microscope image (b) of the negative electrode composite material.
[0029] Figure 2 V2O3 / C@Fe x Mn y O z XRD spectrum of the negative electrode composite material.
[0030] Figure 3 V2O3 / C@Fe x Mn y O zNitrogen adsorption / desorption curves of the negative electrode composite material.
[0031] Figure 4 V2O3 / C@Fe x Mn y O z GCD curve of negative electrode composite material.
[0032] Figure 5 The GCD curves are for Examples 1-3 and Comparative Examples 1-2.
[0033] Figure 6 V2O3 / C@Fe x Mn y O z EIS electrochemical impedance spectroscopy of the negative electrode composite material.
[0034] Figure 7 V2O3 / C@Fe x Mn y O z Cycle life curve of negative electrode composite material. Detailed Implementation
[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0036] Example 1: V2O3 / C@Fe x Mn y O z Preparation of negative electrode composite materials
[0037] (1) Preparation of precursor V2O3 / C:
[0038] Weigh 1g of ammonium metavanadate and 0.25g of activated carbon powder, pour them into a porcelain boat, stir them evenly, and then place them in a tube furnace at 800℃ for high-temperature calcination for 2 hours to obtain the precursor V2O3 / C.
[0039] (2) Preparation of material V2O3 / C@FeMn-LDH:
[0040] Weigh 30 mg of V2O3 / C and disperse it in 20 ml of water. Sonicate for 30 min to ensure uniform dispersion. Record this as solution 1.
[0041] Weigh out 1 mmol of ferric nitrate nonahydrate and 1 mmol of manganese acetate tetrahydrate and dissolve them in 20 ml of deionized water. Stir for 20 minutes. Weigh out 0.404 g of ferric nitrate nonahydrate and 0.2451 g of manganese acetate tetrahydrate and dissolve them in 20 ml of deionized water. This solution is denoted as solution 2.
[0042] Dissolve 3 mmol (0.1818 g) of urea in 20 ml of water and stir for 10 min. Record this solution as solution 3 and set aside.
[0043] First, pour solution 1 into solution 2 and stir to mix the solutions evenly. Then, pour solution 3 into the solution and stir for 5 minutes to obtain a mixture. Pour the mixture into a polytetrafluoroethylene reactor and react at 130°C for 10 hours. After the reaction is complete, centrifuge the solid precipitate, wash it with deionized water, and dry it in a vacuum drying oven to obtain material V2O3 / C@FeMn-LDH.
[0044] (3) V2O3 / C@Fe x Mn y O z Preparation of negative electrode composite materials:
[0045] V2O3 / C@FeMn-LDH was poured into a ceramic boat, which was then placed in a tube furnace and oxidized at 300℃ for 2 hours to obtain the final V2O3 / C@Fe x Mn y O z Negative electrode composite material.
[0046] Figure 1 Scanning electron micrographs of V2O3 / C (a) and V2O3 / C@Fe x Mn y O z Scanning electron microscope image (b) of the negative electrode composite material. As can be seen from the image, the surface of the precursor V2O3 / C is not as smooth as the surface of the carbon block, but is covered with a rough V2O3 coating, which provides a basis for the subsequent synthesis of the composite material. Figure 1 SEM images in b show the prepared V2O3 / C@Fe. x Mn y O z The negative electrode composite material is a blocky structure wrapped in countless small spheres. It can be seen that the irregular stacking gives the material a lot of mesoporous structure, which is conducive to the transfer and transport of electrons between the material and the electrolyte.
[0047] Figure 2 V2O3 / C@Fe x Mn y O z The XRD spectrum of the negative electrode composite material shows that the V2O3 / C@FexMnyOz electrode material exhibits XRD diffraction peaks characteristic of rhombic V2O3, confirming the presence of V2O3. Furthermore, the presence of new diffraction peaks can be attributed to the presence of Fe in the composite material. x Mn y O z .
[0048] Figure 3 V2O3 / C@Fe x Mn y O z The nitrogen adsorption / desorption curves of the negative electrode composite material show that V2O3 / C@Fe x Mn y O z The negative electrode composite material contains a mesoporous structure, and BJH analysis reveals that V2O3 / C@Fe x Mn y O z The average pore size of the negative electrode composite material is 5.2–5.7 nm.
[0049] The prepared V2O3 / C@Fe x Mn y O z The negative electrode composite material was subjected to quantitative analysis using map, and the analysis results are shown in the table below:
[0050] Table 1. V₂O₃ / C@Fe x Mn y O z Quantitative analysis of negative electrode composite materials using map
[0051] element number of atoms Normalized quality (%) atom(%) C 6 27.84 48.75 O 8 25.34 33.31 V 23 6.67 2.76 Mn 25 9.91 3.79 Fe 26 30.24 11.39 100.00 100.00
[0052] As can be seen from Table 1, based on simple quantitative analysis using the map, this material should be V2O3 / C@Fe. 8.25 Mn 2.76 O 21.22 .
[0053] Example 2:
[0054] In this embodiment, the amounts of ferric nitrate nonahydrate and manganese acetate tetrahydrate in the preparation process of material V2O3 / C@FeMn-LDH in step (2) are adjusted to prepare different V2O3 / C@Fe x Mn y O z The negative electrode composite material contains 1 mmol of ferric nitrate nonahydrate and 3 mmol of manganese acetate tetrahydrate. Specifically, 0.404 g of ferric nitrate nonahydrate and 0.7353 g of manganese acetate tetrahydrate are dissolved in 20 ml of deionized water and stirred for 20 min to obtain solution 2. Other operating procedures are basically the same as in Example 1.
[0055] Example 3:
[0056] In this embodiment, the amounts of ferric nitrate nonahydrate and manganese acetate tetrahydrate in the preparation process of material V2O3 / C@FeMn-LDH in step (2) are adjusted to prepare different V2O3 / C@Fex Mn y O z The negative electrode composite material contains 3 mmol of ferric nitrate nonahydrate and 1 mmol of manganese acetate tetrahydrate. Specifically, 1.212 g of ferric nitrate nonahydrate and 0.2451 g of manganese acetate tetrahydrate are dissolved in 20 ml of deionized water and stirred for 20 min to obtain solution 2. Other operating steps are basically the same as in Example 1.
[0057] Example 4:
[0058] This embodiment also uses the V2O3 / C@Fe prepared in Examples 1-3. x Mn y O z Anode composite material was used to prepare the anode V2O3 / C@Fe. x Mn y O z The electrode is prepared as follows:
[0059] Cut two pieces of nickel foam, each 1cm x 1.1cm in size, and soak them in 3mol / L hydrochloric acid for 20 minutes. After soaking, ultrasonically clean them in 15mL of acetone for 3 minutes, then soak them for 12 minutes. Rinse them several times with deionized water to ensure that impurities on the surface of the nickel foam are thoroughly cleaned. Place the cleaned nickel foam in a vacuum drying oven and dry it at 60℃ for 12 hours for later use. Weigh 8mg of the active material V2O3 / C@Fe in a ratio of 8:1:1. x Mn y O z 1 mg of acetylene black and 1 mg of PTFE (dissolved in 50 μL of N-methylpyrrolidone) were mixed with an appropriate amount of ethanol to obtain a solution. The solution was then ultrasonically dispersed in an ultrasonic cleaner for 0.5 h. Finally, the uniformly dispersed solution was dropped onto two pieces of nickel foam and vacuum dried at 100 °C for 8 h. The mixture was then pressed into thin sheets using a tablet press to obtain the negative electrode V2O3 / C@Fe. x Mn y O z electrode.
[0060] With negative electrode V2O3 / C@Fe x Mn y O z The electrode used was the working electrode, the platinum sheet electrode was the counter electrode, and the standard Hg / HgO electrode was the reference electrode. The electrolyte was a 3 mol / L KOH solution. The negative electrode V2O3 / C@Fe was measured using a CHI660E electrochemical workstation (Shanghai Chenhua). x Mn y O z The electrochemical performance of the electrode was specifically tested as follows:
[0061] (1) Electrode activation treatment:
[0062] The electrode materials in Examples 1 to 3 were activated by cyclic voltammetry (CV). The voltage range of the CV curve was 0-0.6V, the scan rate was 100mV / s, and the number of cycles was 100. After activation, the electrode reached a stable state.
[0063] (2) GCD (Galvanic charge-discharge curve) test
[0064] The capacitance of the material was tested using constant current charge-discharge curves. In a 3 mol / L KOH electrolyte, the high potential was set to 0 V, the low potential to -1 V, and current densities of 1 A / g, 2 A / g, 4 A / g, 6 A / g, 8 A / g, and 10 A / g were used to investigate the capacitance of the V₂O₃ / C@Fe material prepared in Example 1. x Mn y O z Anode V2O3 / C@Fe obtained from anode composite material x Mn y O z The capacitance of the electrode at current densities of 1-10 A / g was investigated, and the results are as follows: Figure 4 As shown.
[0065] Figure 4 V2O3 / C@Fe x Mn y O z The GCD curve of the negative electrode composite material shows that, based on the V2O3 / C@Fe prepared in Example 1, x Mn y O z Anode V2O3 / C@Fe obtained from anode composite material x Mn y O z The specific capacitances of the electrodes at current densities of 1-10 A / g are 1261.3 F / g, 682.4 F / g, 408.8 F / g, 277.8 F / g, 200.6 F / g, and 147.2 F / g, respectively.
[0066] Tests showed that in a 3 mol / L KOH electrolyte, at a current density of 1 A / g, the V₂O₃ / C@Fe prepared in Examples 1-3... x Mn y O z Anode V2O3 / C@Fe obtained from anode composite material x Mn y O zThe electrode specific capacitances were 1261.3 F / g, 968.2 F / g, and 665.3 F / g, respectively. This indicates that the V2O3 / C@Fe electrode prepared in Example 1... x Mn y O z Anode V2O3 / C@Fe obtained from anode composite material x Mn y O z The electrode has the highest specific capacitance and the best performance.
[0067] (3) EIS (Electrochemical Impedance) test:
[0068] To investigate the internal characteristics of the electrode material, an analysis was conducted on the V2O3 / C@Fe electrode prepared in Example 1. x Mn y O z Anode V2O3 / C@Fe obtained from anode composite material x Mn y O z Electrochemical impedance spectroscopy (EIS) was performed on the electrodes, with a frequency range of 0.01 Hz to 100 kHz. The measured EIS impedance diagrams were analyzed using a simulated equivalent circuit method, and the results are as follows. Figure 6 As shown.
[0069] Figure 6 V2O3 / C@Fe x Mn y O z The EIS electrochemical impedance spectroscopy (EIS) plot of the negative electrode composite material shows that the curve exhibits a semi-circular shape in the high-frequency region. The intercept with the x-axis and the diameter of the semi-circle represent the internal resistance (Rs) and charge transfer resistance (Rct) of the electrode material, respectively. Rs consists of the resistance between the active material, the current collector, and the electrolyte, while Rct consists of the redox reaction and the double-layer capacitor (CL) on the electrode surface. In the low-frequency region, it is a straight line, representing the diffusion and transport of ions during electrochemical behavior. The test was conducted using V2O3 / C@Fe prepared in Example 1. x Mn y O z Anode V2O3 / C@Fe obtained from anode composite material x Mn y O z The charge transfer resistance of the electrode is 0.849 Ω, and the internal resistance of the material is 0.051 Ω. Furthermore, the slope of the line in the low-frequency region is 1.01, indicating that the material has low ion diffusion resistance.
[0070] (4) Cyclic stability test:
[0071] Cyclic stability testing of the material was performed using a constant current charge-discharge curve. The current density used was 4 A / g, and the potential window was -1 to 0 V. After 5000 cycles, the material was based on the V2O3 / C@Fe prepared in Example 1. x Mn y O z Anode V2O3 / C@Fe obtained from anode composite material x Mn y O z The capacity retention rate of the electrode was 89.13%.
[0072] Comparative Example 1:
[0073] Weigh 1g of ammonium metavanadate and 0.25g of activated carbon powder, pour them into a porcelain boat, stir them evenly, and then place them in a tube furnace at 800℃ for high-temperature calcination for 2 hours to obtain V2O3 / C.
[0074] Two pieces of nickel foam, each 1cm x 1.1cm in size, were cut and soaked in 3mol / L hydrochloric acid for 20 minutes. After soaking, they were ultrasonically cleaned in 15mL acetone for 3 minutes, then soaked for 12 minutes. They were then rinsed several times with deionized water to ensure all impurities on the surface of the nickel foam were removed. The cleaned nickel foam was then placed in a vacuum drying oven and dried at 60℃ for 12 hours. 8mg of active material V2O3 / C, 1mg of acetylene black, and 1mg of PTFE (dissolved in 50µL of N-methylpyrrolidone) were weighed in a ratio of 8:1:1. An appropriate amount of ethanol was added to obtain a mixture, which was then ultrasonically dispersed in an ultrasonic cleaner for 0.5 hours. Finally, the evenly dispersed mixture was dropped onto the two pieces of nickel foam and vacuum dried at 100℃ for 8 hours. The mixture was then pressed into thin sheets using a tablet press to obtain the negative electrode V2O3 / C electrode.
[0075] like Figure 5 As shown, the negative electrode V2O3 / C electrode has a specific capacitance of 22.3 F / g in a 3 mol / L KOH electrolyte at a current density of 1 A / g.
[0076] Comparative Example 2:
[0077] (1) Preparation of precursor V2O3 / C:
[0078] Weigh 1g of ammonium metavanadate and 0.25g of activated carbon powder, pour them into a porcelain boat, stir them evenly, and then place them in a tube furnace at 800℃ for high-temperature calcination for 2 hours to obtain the precursor V2O3 / C.
[0079] (2) Preparation of material V2O3 / C@FeMn-LDH:
[0080] Weigh 30 mg of V2O3 / C and disperse it in 20 ml of water. Sonicate for 30 min to ensure uniform dispersion. Record this as solution 1.
[0081] Weigh out 1 mmol of ferric nitrate nonahydrate and 1 mmol of manganese acetate tetrahydrate and dissolve them in 20 ml of deionized water. Stir for 20 minutes. Weigh out 0.404 g of ferric nitrate nonahydrate and 0.2451 g of manganese acetate tetrahydrate and dissolve them in 20 ml of deionized water. This solution is denoted as solution 2.
[0082] Dissolve 3 mmol (0.1818 g) of urea in 20 ml of water and stir for 10 min. Record this solution as solution 3 and set aside.
[0083] First, pour solution 1 into solution 2 and stir to mix the solutions evenly. Then, pour solution 3 into the solution and stir for 5 minutes to obtain a mixture. Pour the mixture into a polytetrafluoroethylene reactor and react at 130°C for 10 hours. After the reaction is complete, centrifuge the solid precipitate, wash it with deionized water, and dry it in a vacuum drying oven to obtain material V2O3 / C@FeMn-LDH.
[0084] Two pieces of nickel foam, each 1cm x 1.1cm in size, were cut and soaked in 3mol / L hydrochloric acid for 20 minutes. After soaking, they were ultrasonically cleaned in 15mL acetone for 3 minutes, then soaked for 12 minutes. They were then rinsed several times with deionized water to ensure that impurities on the surface of the nickel foam were thoroughly cleaned. The cleaned nickel foam was then placed in a vacuum drying oven and dried at 60℃ for 12 hours. 8mg of active material V2O3 / C@FeMn-LDH, 1mg of acetylene black, and 1mg of PTFE (dissolved in 50µL of N-methylpyrrolidone) were weighed in a ratio of 8:1:1. An appropriate amount of ethanol was added to obtain a mixture, which was then ultrasonically dispersed in an ultrasonic cleaner for 0.5 hours. Finally, the evenly dispersed mixture was dropped onto the two pieces of nickel foam and vacuum dried at 100℃ for 8 hours. The mixture was then pressed into thin sheets using a tablet press to obtain the negative electrode V2O3 / C@FeMn-LDH electrode.
[0085] like Figure 5 As shown, the negative electrode V2O3 / C@FeMn-LDH electrode has a specific capacitance of 228.8 F / g in a 3 mol / L KOH electrolyte at a current density of 1 A / g.
[0086] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.
Claims
1. A V2O3 / C@Fe x Mn y O z The negative electrode composite material is characterized by, The V2O3 / C@Fe x Mn y O z The negative electrode composite material is a blocky structure consisting of countless small spheres, namely V2O3 / C@Fe. x Mn y O z The negative electrode composite material has a mesoporous structure with an average pore size of 5.2–5.7 nm, and the x:y:z ratio is 8.25:2.76:21.
22.
2. The V2O3 / C@Fe according to claim 1 x Mn y O z A method for preparing a negative electrode composite material, characterized in that, include: (1) Preparation of precursor V2O3 / C: Ammonium metavanadate and activated carbon powder were stirred evenly and then calcined at high temperature to obtain the precursor V2O3 / C. (2) Preparation of V2O3 / C@FeMn-LDH: Disperse V2O3 / C evenly in water and record as solution 1; dissolve ferric nitrate nonahydrate and manganese acetate tetrahydrate in water and stir thoroughly to dissolve, then record as solution 2; dissolve urea in water and stir thoroughly to dissolve, then record as solution 3. Solution 1 was added to solution 2 and stirred until homogeneous. Then solution 3 was added and stirred until homogeneous to obtain a mixed solution. The mixed solution was subjected to hydrothermal reaction. After the reaction was completed, the solution was centrifuged, washed, and dried to obtain V2O3 / C@FeMn-LDH. (3) V2O3 / C@Fe x Mn y O z Preparation of negative electrode composite materials: V2O3 / C@FeMn-LDH was oxidized at low temperature (280–320 °C) for 100–150 min to obtain V2O3 / C@Fe x Mn y O z A negative electrode composite material, wherein x:y:z = 8.25:2.76:21.
22.
3. The V2O3 / C@Fe according to claim 2 x Mn y O z A method for preparing a negative electrode composite material, characterized in that, In step (1), the mass ratio of ammonium metavanadate to activated carbon powder is 4:1 to 3:
1.
4. The V2O3 / C@Fe according to claim 2 x Mn y O z A method for preparing a negative electrode composite material, characterized in that, In step (1), the high-temperature calcination conditions are calcination at 750-850℃ for 100-150 min.
5. The V2O3 / C@Fe according to claim 2 x Mn y O z A method for preparing a negative electrode composite material, characterized in that, In step (2), the mass ratio of V2O3 / C, ferric nitrate nonahydrate, manganese acetate tetrahydrate and urea is 60-80 mg: 400-450 mg: 240-260 mg: 180-240 mg.
6. The V2O3 / C@Fe according to claim 2 x Mn y O z A method for preparing a negative electrode composite material, characterized in that, In step (2), the hydrothermal reaction is carried out at 120-140°C for 9-11 hours.
7. The V2O3 / C@Fe according to claim 1 x Mn y O z Application of negative electrode composite materials as negative electrode materials for supercapacitors.
8. The application according to claim 7, characterized in that, The application is as follows: Two pieces of nickel foam were soaked in hydrochloric acid, and after soaking, they were washed and dried to obtain the treated nickel foam. V2O3 / C@Fe x Mn y O z Acetylene black, PTFE, and ethanol were mixed and ultrasonically dispersed. The uniformly dispersed mixture was then dropped onto two pieces of treated nickel foam, vacuum dried, and then pressed into thin sheets using a tablet press to obtain the negative electrode V2O3 / C@Fe. x Mn y O z electrode.
9. The application according to claim 8, characterized in that, The concentration of the hydrochloric acid is 2–4 mol / L; The V2O3 / C@Fe x Mn y O z The mass ratio of acetylene black to PTFE is 7.5–8.5:0.9–1.1:0.9–1.1.