Spherical Co3O4-coated Cu3Mo2O9 nano-film electrode material and preparation method and application thereof

Abstract

The invention discloses a preparation method of a spherical Co3O4-coated Cu3Mo2O9 nano-film electrode material, and belongs to the technical field of electrode materials. The preparation method comprises the following steps: firstly, taking foamed nickel as a template, generating Co3O4 on the foamed nickel in situ through a hydrothermal reaction, then adding Cu (NO3) 2.6 H2O and NaMoO4 into deionized water to obtain a uniform solution, soaking the Co3O4 generated on the foamed nickel in situ into the uniform solution, and successfully preparing the Co3O4-coated Cu3Mo2O9 film electrode material on the foamed nickel by adopting a simple hydrothermal deposition method. The electrode material shows excellent electrochemical performance.

Description

[0001] This application is a divisional application. The original application is entitled "A Method for Preparing Spherical Co3O4@Cu3Mo2O9 Nanofilm Electrode Material." The application number is 202411363901.7, and the filing date is September 28, 2024. Technical Field

[0002] The present invention belongs to the technical field of electrode materials, and in particular relates to a method for preparing a spherical Co3O4@Cu3Mo2O9 nano-thin film electrode material. Background Art

[0003] Increasing environmental pollution and decreasing renewable energy supply highlight the urgent need to develop materials required for next-generation energy storage solutions. Supercapacitors and lithium-ion batteries have become key players in the field of electrochemical energy storage, among which supercapacitors have attracted the attention of researchers due to their excellent power density, ultra-long cycle life and fast charging capability. These supercapacitors can be divided into double-layer capacitors (EDLCs) and pseudocapacitors based on different charge storage mechanisms. EDLCs store energy by separating charges at the electrode / electrolyte interface, while pseudocapacitors rely on Faradaic redox reactions to store energy. Although supercapacitors offer significant benefits, their current applications are limited and improvements are needed in terms of cycling stability and overall efficiency. The effectiveness and performance of supercapacitors depend on the structural design and electrochemical properties of the electrode materials used.

[0004] Transition metal oxides (TMOs) have attracted significant attention among these materials due to their diverse oxidation states, sample preparation methods, and high theoretical specific capacitance. Various metal oxides, including MnO2, NiO, Fe2O3, and Co3O4, have been used as electrode materials for supercapacitors. Among them, Co3O4 is considered the preferred electrode material for supercapacitors due to its high theoretical capacitance, low cost, environmental friendliness, and excellent electrochemical stability. However, in practical applications, Co3O4 exhibits a low electron transfer rate during the reaction, which impairs its electrochemical performance. Summary of the Invention

[0005] To address the above technical issues, the present invention proposes a method for preparing spherical Co3O4@Cu3Mo2O9 nanofilm electrode materials. The molybdenum-based oxide Cu3Mo2O9 has strong catalytic properties. Combining Cu3Mo2O9 with Co3O4 can promote the electrochemical reactions of the cathode material and improve its electrochemical performance. This is because the spherical structure provides a relatively large specific surface area, more reaction sites, and a shorter diffusion path length, allowing electrolyte ions to easily and quickly penetrate the electrode material, resulting in low resistance and improved electrochemical performance. Furthermore, Co3O4 provides a large open space, serving as a framework that facilitates the formation of Cu3Mo2O9 and successfully inhibits the agglomeration of NiCo2O4, also contributing to improved electrochemical performance.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a spherical Co3O4@Cu3Mo2O9 nanofilm electrode material comprises the following steps:

[0008] Co(NO3)2·6H2O and urea are dissolved in deionized water to obtain a red solution, nickel foam is added to the red solution and heated in a hydrothermal reactor, cooled naturally to room temperature, washed, dried, and calcined to obtain a Co3O4 / / nickel foam electrode material;

[0009] Cu(NO3)2·6H2O and NaMoO4 are added to deionized water to obtain a uniform solution (Cu3Mo2O9), the Co3O4 / / nickel foam electrode material is immersed in the uniform solution, heated again in a hydrothermal reactor, naturally cooled to room temperature, washed, dried, and calcined again to obtain a Co3O4@Cu3Mo2O9 nanofilm electrode material.

[0010] Furthermore, in the red solution, the usage ratio of Co(NO3)2·6H2O, urea and deionized water is 0.4g:0.3g:50mL.

[0011] Furthermore, the heating conditions are: temperature 130° C., time 5 h; the calcination conditions are: heating rate 3° C. / min, temperature 320° C., time 2 h.

[0012] Furthermore, in the homogeneous solution, the usage ratio of Cu(NO3)2·6H2O, NaMoO4 and deionized water is 0.31 g:0.28 g:30 mL.

[0013] Furthermore, the conditions for the reheating treatment are: temperature 160° C., time 6 h; the conditions for the re-calcination are: heating rate 3° C. / min, temperature 400° C., time 2 h.

[0014] The present invention also provides a spherical Co3O4@Cu3Mo2O9 nano-thin film electrode material prepared by the above preparation method.

[0015] The present invention also provides an application of the spherical Co3O4@Cu3Mo2O9 nano-film electrode material in preparing a supercapacitor.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects:

[0017] The present invention successfully prepared a binder-free Co3O4@Cu3Mo2O9 thin film electrode material on nickel foam using a simple hydrothermal deposition method. The electrode exhibited excellent electrochemical performance. The Co3O4@Cu3Mo2O9 electrode material had a high specific capacitance of 942Fg-1 at 0.5Ag-1. The assembled Co3O4@Cu3Mo2O9 / / AC supercapacitor had an energy density of 40WhKg-1 at a power density of 800WKg-1. In addition, after 5000 cycles, the capacity retention rate of Co3O4@Cu3Mo2O9 / / AC reached a maximum of 80.59%, indicating good cycling stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0019] Figure 1 a is the SEM image of Co3O4@Cu3Mo2O9 (30μm); b is the SEM image of Co3O4@Cu3Mo2O9 (10μm); c is the EDS image of Co3O4@Cu3Mo2O9;

[0020] Figure 2 a is the XRD diffraction pattern of Co3O4, Co3O4@Cu3Mo2O9, and Cu3Mo2O9; b is the XPS spectrum of Co3O4@Cu3Mo2O9; c is the Mo3d high-resolution X-ray photoelectron spectrum of Co3O4@Cu3Mo2O9; d is the Co2p high-resolution X-ray photoelectron spectrum of Co3O4@Cu3Mo2O9; e is the Cu2p high-resolution X-ray photoelectron spectrum of Co3O4@Cu3Mo2O9; f is the O1s high-resolution X-ray photoelectron spectrum of Co3O4@Cu3Mo2O9;

[0021] Figure 3a is the nitrogen adsorption-desorption curve of Co3O4, Cu3Mo2O9 and Co3O4@Cu3Mo2O9; b is the pore size distribution curve of Co3O4, Cu3Mo2O9 and Co3O4@Cu3Mo2O9; c is the contact angle of Co3O4; d is the contact angle of Cu3Mo2O9; e is the contact angle of Co3O4@Cu3Mo2O9;

[0022] Figure 4 a is the CV curve of Co3O4@Cu3Mo2O9 at different scan rates; b is the comparison of CV curves of Co3O4, Cu3Mo2O9 and Co3O4@Cu3Mo2O9 at the same potential window and scan rate; c is the GCD curve of Co3O4, Cu3Mo2O9 and Co3O4@Cu3Mo2O9 at a current density of 1.0Ag-1; d is the GCD curve of Co3O4@Cu3Mo2O9 at different current densities; e is the specific capacitance of Co3O4, Cu3Mo2O9 and Co3O4@Cu3Mo2O9 at different current densities; f is the Nyquist plot of Co3O4, Cu3Mo2O9 and Co3O4@Cu3Mo2O9;

[0023] Figure 5 a is the CV curve of Co3O4@Cu3Mo2O9 and AC electrode materials; b is the CV curve of Co3O4@Cu3Mo2O9 / / AC device at different voltage windows; c is the CV curve of Co3O4@Cu3Mo2O9 / / AC device at different scan rates; d is the GCD curve of Co3O4@Cu3Mo2O9 / / AC device at different current densities; e is the GCD curve of Co3O4 / / AC device, Cu3Mo2O9 / / AC device and Co3O4@C GCD curve of the u3Mo2O9 / / AC device at 10Ag-1; f is the Nyquist plot of the Co3O4 / / AC device, Cu3Mo2O9 / / AC device and Co3O4@Cu3Mo2O9 / / AC device; g is the energy density and power density curve of the Co3O4@Cu3Mo2O9 / / AC device; h is the cycling stability test of the Co3O4 / / AC device, Cu3Mo2O9 / / AC device and Co3O4@Cu3Mo2O9 / / AC device;

[0024] Figure 6 a is the relationship between the peak current and scan rate of Co3O4@Cu3Mo2O9 / / AC; b is the contribution of capacitance at a scan rate of 50mVs-1 shown by the Co3O4@Cu3Mo2O9 / / ACCV curve; c is the relative contribution of diffusion and capacitance at different scan rates of Co3O4@Cu3Mo2O9 / / AC. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] Unless otherwise specified, the "room temperature" in the present invention refers to 20-30°C.

[0031] The raw materials used in the present invention are all purchased from the market.

[0032] The technical solution of the present invention is further illustrated by the following examples.

[0033] Example 1

[0034] Preparation of Co3O4 electrode material:

[0035] 0.437 g Co(NO3)2·6H2O and 0.312 g urea were dissolved in 50 mL deionized water to form a uniform red solution. Nickel foam (1 cm×2 cm, NF) was added to the red solution and placed in a 100 mL hydrothermal reactor and heated to 130°C. After keeping warm for 5 hours, it was naturally cooled to room temperature. The sample was taken out, washed with deionized water, and dried at 60°C for 2 hours. After drying, it was placed in a muffle furnace for calcination and heated to 320°C at a heating rate of 3°C / min and calcined for 2 hours to obtain Co3O4 / / NF electrode material.

[0036] Preparation of Co3O4@Cu3Mo2O9 electrode material:

[0037] 0.31gCu(NO3)2·6H2O and 0.28gNaMoO4 were added to 30mL deionized water to mix into a uniform solution. The Co3O4 / / NF electrode material was immersed in the above solution and transferred to a 50mL hydrothermal reactor. It was kept at 160℃ for 6h. After naturally cooling to room temperature, the sample was taken out, washed with deionized water, and dried at 60℃. Finally, the sample was heated to 400℃ in a muffle furnace at a heating rate of 3℃ / min and calcined for 2h to obtain Co3O4@Cu3Mo2O9.

[0038] Control group 1

[0039] Preparation of Cu3Mo2O9 electrode material:

[0040] 0.31 g Cu(NO3)2·6H2O and 0.28 g NaMoO4 were added to 30 mL deionized water and mixed into a uniform solution. Nickel foam (1 cm×2 cm, NF) was immersed in the above solution and transferred to a 50 mL hydrothermal reactor. It was kept at 160°C for 6 h. After naturally cooling to room temperature, the sample was taken out, washed with deionized water, and dried at 60°C. Finally, the sample was heated to 400°C in a muffle furnace at a heating rate of 3°C / min and calcined for 2 h to obtain Cu3Mo2O9.

[0041] Figure 1 Figures a (30 μm) and b (10 μm) show SEM images of Co₃O₄@Cu₃Mo₂O₆ at different magnifications. As can be seen in Figures a and b, the micromorphology of Co₃O₄@Cu₃Mo₂O₆ exhibits a porous spherical structure. This porous spherical structure facilitates charge accumulation and transfer. Figure c shows an EDS image of Co₃O₄@Cu₃Mo₂O₆, demonstrating the uniform distribution of Co, Cu, Mo, and O elements throughout the Co₃O₄@Cu₃Mo₂O₆.

[0042] The purity and crystal structure information of the samples were analyzed by X-ray diffraction (XRD).

[0043] Figure 2 a in the figure is the XRD diffraction pattern of the prepared samples Co3O4, Co3O4@Cu3Mo2O9 and Cu3Mo2O9. It can be seen that the diffraction peaks of the samples are sharp and clear, and no extra peaks are observed, confirming that Co3O4@Cu3Mo2O9 is composed of Co3O4 and Cu3Mo2O9. b is the XPS spectrum of Co3O4@Cu3Mo2O9, which confirms the presence of Cu, Co, Mo and O elements. High-resolution x-ray photoelectron spectroscopy is used to fit Co3O4@Cu3Mo2O9. Figure 2 As can be seen from Figure c, in Co3O4@Cu3Mo2O9, the Mo3d spectrum consists of two main peaks, which can be attributed to the spin-orbit splitting of Mo3d5 / 2 and Mo3d3 / 2 at binding energies of 232.4 and 235.3 eV, respectively. These peaks confirm the existence of Mo6+ and Mo4+ states. Figure 2 As can be seen from the d in the figure, the Co2p spectrum has two main peaks at 779.6 and 795.8 eV, which are related to the Co2+ and Co3+ states respectively, and there are also two satellite peaks at 784.2 and 801.9 eV. Figure 2 As can be seen from the e in the Cu2p spectrum, the two main peaks of Cu2p3 / 2 and Cu2p1 / 2 are located at 934.6 and 954.7 eV respectively, and the satellite peaks are located at 942.8 and 962.7 eV, confirming the existence of Cu2+ state. Figure 2 As can be seen from the figure, the high-resolution O1s spectrum shows three peaks centered at 530.2, 530.8, and 531.9 eV. The peak at 530.2 eV is mainly formed by O2- attached to Co-O and Cu and Mo atoms, the peak at 530.8 eV is attributed to the Mo-O bond, and the peak at 531.9 eV is attributed to the surface hydroxyl groups.

[0044] In order to further explore the pore size distribution and specific surface area of Co3O4, Cu3Mo2O9 and Co3O4@Cu3Mo2O9, nitrogen adsorption and desorption tests were carried out on the samples. The pore size distribution was analyzed using the BJH model. The results are as follows: Figure 3 As shown in b. According to the BJH adsorption curve ( Figure 3 From a), we know that the pore size of Co3O4@Cu3Mo2O9 is mainly between 5-20 nm, which proves that the main forms of pores in the sample are micropores and small-sized mesopores. Figure 3a in the graph is the nitrogen adsorption and desorption test results of Co3O4, Cu3Mo2O9 and Co3O4@Cu3Mo2O9. Co3O4@Cu3Mo2O9 shows obvious IV type curve characteristics and H4 type hysteresis loop, which proves that there are a large number of micropores in the material. In addition, the wettability of Co3O4, Cu3Mo2O9 and Co3O4@Cu3Mo2O9 was tested by contact angle, as shown in Figure 2. Figure 3 As shown in Figure c, compared with Co3O4 and Cu3Mo2O9, Co3O4@Cu3Mo2O9 has the smallest contact angle of 38.15°, which indicates that Co3O4@Cu3Mo2O9 has the best wettability.

[0045] Electrochemical tests were carried out on the flower-shaped Co3O4@Cu3Mo2O9 material. The electrode material was subjected to CV tests in 6MKOH aqueous solution at room temperature, and the test potential window was 0~0.5V. Figure 4 Figure a is the CV curve of Co3O4@Cu3Mo2O9 electrode material at different scan rates. It can be seen from the curve that as the scan progresses, the current peaks of the cathode and anode move toward the two poles and the current of the CV curve increases in proportion to the increase in the scan rate, indicating that the material has the characteristics of fast charging and discharging. Figure 4 Figure b compares the CV curves of Co3O4, Cu3Mo2O9, and Co3O4@Cu3Mo2O9 at the same potential window and scan rate (0-0.45V potential window, 100mVs-1 scan rate). The curve shape and enclosed area indicate that Co3O4@Cu3Mo2O9 has the highest specific capacity. Compared to Co3O4 and Cu3Mo2O9, Co3O4@Cu3Mo2O9 is more rectangular in shape and has a wider redox peak, indicating that its capacitance is a function of both pseudocapacitance and double-layer capacitance mechanisms. The widening peak may be due to the superposition of the redox peaks of Co3O4 and Cu3Mo2O9. This composite material has a multi-layer core-shell structure, with the primary capacitance provided by the two active materials, Co3O4 and Cu3Mo2O9. Figure 4Figure c represents the GCD curves of three electrode materials, Co3O4, Cu3Mo2O9, and Co3O4@Cu3Mo2O9, at a current density of 1.0Ag⁻¹. It is clearly observed that the discharge time of Co3O4@Cu3Mo2O9 is much longer than that of the other two materials, confirming that Co3O4 loaded with Cu3Mo2O9 improves the material's specific capacitance. The GCD curve of Co3O4@Cu3Mo2O9 resembles a superposition of the GCD curves of Co3O4 and Cu3Mo2O9. Analysis shows that both Co3O4 and Cu3Mo2O9 contribute to the material's overall specific capacity. The synergistic effect of multiple active substances yields electrochemical performance superior to that of a single material. The multi-layered "shell-core" structure enhances interfacial activity between the electrode material and the electrolyte, enriching redox reactions. Figure 4 Figure d is the GCD curve of Co3O4@Cu3Mo2O9 at different current densities. It can be seen that the discharge time of Co3O4@Cu3Mo2O9 curve is the longest. Figure 4 Figure (e) shows the specific capacitance of Co3O4, Cu3Mo2O9, and Co3O4@Cu3Mo2O9 at different current densities. It can be seen that the specific capacity of Co3O4@Cu3Mo2O9 (942 F / g) is much greater than that of Co3O4 (329 F / g) and Cu3Mo2O9 (221 F / g). Figure (f) shows the Nyquist plots of Co3O4, Cu3Mo2O9, and Co3O4@Cu3Mo2O9. It can be seen that the slope of the Co3O4@Cu3Mo2O9 curve is the largest, indicating the lowest impedance.

[0046] Before assembling the Co3O4@Cu3Mo2O9 / / AC device, the prepared positive and negative electrode materials need to be tested by CV. First, the negative electrode is tested by CV in the voltage window of -1~0V. The results are as follows: Figure 5 As shown in a. As can be seen from Figure a, the CV curve of the negative electrode material AC / NF has no obvious redox peak, which indicates that the AC / NF material has obvious double-layer capacitance characteristics. The electrochemical performance of the assembled asymmetric supercapacitor Co3O4@Cu3Mo2O9 / / AC was tested in a double-electrode system. Figure 5As can be seen in Figure b, the device exhibits a distinct redox peak within the 0-1.5V voltage window. This is due to the redox reaction occurring in the positive electrode material. As the voltage is increased, the electrode material polarizes, causing significant deformation in the CV curve. This is detrimental to charge and ion transport. Therefore, the device voltage window was set within the 0-1.5V range. CV and GCD tests were performed on the device within the 0-1.5V voltage window. As can be seen in Figure c, the CV curve maintains a relatively consistent shape with increasing scan rate, demonstrating good rate performance. The GCD test in Figure d shows a relatively symmetrical curve, indicating high Coulombic efficiency and electrochemical reversibility. Co3O4 / / AC, Cu3Mo2O9 / / AC, and Co3O4@Cu3Mo2O9 / / AC were compared at 1.0Ag-1. As shown in Figure e, Co3O4@Cu3Mo2O9 / / AC has the longest discharge time, which can be attributed to the synergistic effect between Co3O4 and Cu3Mo2O9. In addition, the conductivity of the three devices, Co3O4 / / AC, Cu3Mo2O9 / / AC, and Co3O4@Cu3Mo2O9 / / AC, was also tested. As shown in Figure f, Co3O4@Cu3Mo2O9 / / AC has the best conductivity. The energy density and power density of Co3O4@Cu3Mo2O9 / / AC were calculated using the formula. As shown in Figure g, at 800WKg-1, Co3O4@Cu3Mo2O9 / / AC has 40WhKg-1. In addition, the cycling stability of Co3O4 / / AC, Cu3Mo2O9 / / AC, and Co3O4@Cu3Mo2O9 / / AC was further tested. As shown in Figure h, after 5000 cycles, the capacity retention rate of Co3O4@Cu3Mo2O9 / / AC was the highest (Co3O4@Cu3Mo2O9 / / AC: 80.59%, Co3O4 / / AC: 50%, Cu3Mo2O9 / / AC: 60.45%), which indicates that Co3O4@Cu3Mo2O9 / / AC has good cycling stability. The charge storage mechanism of supercapacitor devices can be qualitatively determined by the peak current at different scan rates, calculated using the following formula (1).

[0047] i=av b #(1)

[0048] In the equation, i(A) represents the peak current, v(mVs-1) represents the scan rate, and a and b are a pair of constants. When b is close to 0.5, it means that the electrode follows the diffusion-controlled charge storage mechanism, and when b is close to 1, it means that the electrode follows the surface-controlled charge storage mechanism. Figure 6As shown in a, the redox peak current is linearly fitted (the slope is represented by b), and the slopes of the redox peak current are 0.87 and 0.82, respectively. This shows that the device exhibits diffusion and capacitance jointly controlled charge storage behavior. In order to further understand the contribution of surface capacitance and diffusion controlled capacitance at a specific scan rate, the following formula (2) can be used for calculation

[0049]

[0050] Where i represents the response current, k1 and k2 are adjustable parameters, and v (mVs-1) represents the voltage scan rate.

[0051] The surface controls the contribution of current to capacitance. Figure 6 Panel b shows the capacitance contribution at a scan rate of 50 mVs-1, where the yellow CV curve represents the capacitance contribution. Figure 6 Figure c shows the changes in capacitance contribution and diffusion contribution in the range of 5-100mVs-1. It can be seen that with the increase of scan rate, the contribution of capacitance gradually increases from 39% to 73%, which indicates that the device is diffusion-controlled at low scan rates, but with the increase of scan rate, the charge storage mechanism tends to capacitance-controlled behavior.

[0052] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A spherical Co3O4@Cu3Mo2O9 nanofilm electrode material, characterized in that: Prepared by the following method: Co(NO3)2·6H2O and urea are dissolved in deionized water to obtain a red solution, nickel foam is added to the red solution and heated in a hydrothermal reactor, cooled naturally to room temperature, washed, dried, and calcined to obtain a Co3O4 / / nickel foam electrode material; Cu(NO3)2·6H2O and NaMoO4 are added to deionized water to obtain a uniform solution, the Co3O4 / / nickel foam electrode material is immersed in the uniform solution, heated again in a hydrothermal reactor, naturally cooled to room temperature, washed, dried, and calcined again to obtain a Co3O4@Cu3Mo2O9 nanofilm electrode material; in the red solution, the amount ratio of Co(NO3)2·6H2O, urea, and deionized water is 0.4g:0.3g:50mL ; The heating conditions are: temperature 130℃, time 5h; the calcination conditions are: heating rate 3℃ / min, temperature 320℃, time 2h; in the uniform solution, the dosage ratio of Cu(NO3)2·6H2O, NaMoO4 and deionized water is 0.31g:0.28g:30mL; the conditions for the secondary heating treatment are: temperature 160℃, time 6h; the conditions for the secondary calcination are: heating rate 3℃ / min, temperature 400℃, time 2h.

2. Use of the electrode material as claimed in claim 1 in preparing a supercapacitor.

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