Composite electrode material and preparation method, supercapacitor

Abstract

The present invention discloses a composite electrode material, a preparation method thereof, and a supercapacitor. The preparation method of the composite electrode material includes: 1) immersing Cu(OH)2 nanowire / copper substrate in a precursor solution to obtain HKUST-1 / copper substrate; the organic ligand in the precursor solution is trimesic acid; the immersion time is 8-12 min; 2) annealing the HKUST-1 / copper substrate to obtain (CuO-Cu2O@C) / copper substrate; the annealing temperature is 400-500 °C; 3) using the (CuO-Cu2O@C) / copper substrate as a working electrode and obtaining the composite electrode material through electrodeposition; the electrolyte for electrodeposition includes nickel chloride and thiourea. The composite electrode material of the present invention makes up for the defects of poor conductivity of nickel sulfide and low specific capacitance of carbon materials, reduces the impedance of the electrode material, improves the rate performance of the composite electrode material, and also enhances the electrochemical stability and energy density of the composite electrode material.

Description

Technical Field

[0001] The present invention specifically relates to a composite electrode material and a preparation method thereof, and a supercapacitor. Background Art

[0002] Supercapacitors are a new type of energy storage element between traditional capacitors and chemical power sources. They have the advantages of high power density, fast charging / discharging capabilities and ultra-long service life, and have received more and more attention in recent years. They can be used not only in new energy vehicles, industrial energy-saving systems, pulse power systems and other fields, but also in the field of consumer electronics. Electrode materials are the core of supercapacitors, which largely determine the performance of supercapacitors. However, the energy density of commercial supercapacitors is still relatively low, which also affects their further development in various fields. Therefore, the development of electrode materials with a wide voltage window and larger specific capacitance has become the main direction of improving supercapacitors.

[0003] Metal sulfide has become one of the most widely used electrode materials for supercapacitors due to its advantages such as easy availability and low price. Among them, nickel sulfide (Ni3S2) has high specific capacitance, low price, safety and pollution-free, and is an ideal supercapacitor electrode material. However, the poor conductivity of nickel sulfide itself limits its application in electrode materials, and its high resistance cannot support its performance at high rates. The application of carbon materials in supercapacitor electrode materials has the defect of poor specific capacitance. At present, there is no technical solution reported in the prior art to combine nickel sulfide with carbon materials to prepare composite electrode materials. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of poor conductivity of nickel sulfide as an electrode material and low specific capacitance of carbon material as an electrode material in the prior art, and provide a composite electrode material and preparation method, and supercapacitor. The composite electrode material of the present invention well compensates for the defects of poor conductivity of nickel sulfide and low specific capacitance of carbon material, reduces the impedance of the electrode material, improves the rate performance under high current, and enables the high specific capacitance of nickel sulfide itself to be reflected, thereby improving the conductivity of the composite electrode material; at the same time, it also enhances the electrochemical stability and energy density of the composite electrode material.

[0005] In the prior art, nickel sulfide has a high specific capacitance, but its poor electrical conductivity limits its application in electrode materials, and carbon materials have good electrical conductivity but poor specific capacitance. At present, there is no report on the technical solution for combining nickel sulfide and carbon materials. In the process of research and development, the inventors found that there are certain technical difficulties in combining the two and overcoming the defects between the two to obtain a composite electrode material with better performance. For example, it is difficult to overcome the problem of uniformly coating the carbon layer with metal-organic frameworks (MOFs, Metal-Organic Frameworks) as the carbon source on the surface of CuO-Cu2O nanowires, and the orderly growth of nickel sulfide on the carbon layer, etc. If these problems are not overcome, it is difficult to obtain a composite electrode material with excellent comprehensive performance such as electrochemical stability, high specific capacity, and high energy density. In addition, conventional carbon materials cannot solve the defect of poor electrical conductivity of nickel sulfide.

[0006] The inventor of the present invention obtained the technical solution of the present invention through creative labor and screening of multiple experimental conditions. For example, HKUST-1 is used as the carbon material, the selection of organic ligands in HKUST-1, the source of metal ions, and the combination of the carbon material with the matrix of the copper substrate, the specific soaking process in the preparation of HKUST-1 / copper substrate, the selection of annealing temperature in the preparation of (CuO-Cu2O@C) / copper substrate, and the selection of electrolyte types during the electrodeposition process, etc., all have a significant impact on the performance of the composite electrode material of the present invention. In the present invention, the above-mentioned many characteristics are cleverly limited to maintain the nanowire array structure, and the carbon layer is uniformly coated on the surface of the CuO-Cu2O nanowires, and nickel sulfide grows uniformly and orderly on the surface of the carbon layer, so that the composite electrode material of the present invention has many excellent properties.

[0007] The technical solution solves the above technical problems.

[0008] The present invention also provides a method for preparing a composite electrode material, which comprises the following steps:

[0009] (1) immersing the Cu(OH)2 nanowire / copper substrate in a precursor liquid to obtain a HKUST-1 / copper substrate; the organic ligand in the precursor liquid is trimesic acid; and the immersion time is 8 to 12 minutes;

[0010] (2) The HKUST-1 / copper substrate is annealed to obtain a (CuO-Cu2O@C) / copper substrate; the annealing temperature is 400-500° C.;

[0011] (3) Using the (CuO-Cu2O@C) / copper substrate as a working electrode, a (CuO-Cu2O@C@Ni3S2) / copper substrate nanocomposite electrode material is obtained by electrodeposition; the electrolyte in the electrodeposition includes nickel chloride and thiourea.

[0012] The expressions of “ / ” and “@” in the present invention are conventional expressions in the art. Specifically, “ / ” generally refers to growth on the surface, for example, the “ / ” in (CuO-Cu2O@C) / copper substrate refers to CuO-Cu2O@C growing on the surface of the copper substrate. “@” generally refers to a core-shell structure, for example, in CuO-Cu2O@C, it refers to a core-shell structure with CuO-Cu2O as the core and C as the shell. (CuO-Cu2O@C@Ni3S2) / copper substrate nanocomposite electrode material refers to a core-shell structure with CuO-Cu2O@C as the core and Ni3S2 as the shell.

[0013] In step (1), it should be noted that the copper source in HKUST-1 is the Cu(OH)2 nanowire. Those skilled in the art are aware that the HKUST-1 refers to a metal-organic framework material with trimesic acid as an organic ligand and copper ions as metal ions. The copper source refers to a substance that can provide metal copper ions for HKUST-1.

[0014] In step (1), the Cu(OH)2 nanowire / copper substrate can be prepared by conventional methods in the art, for example, by immersing the copper substrate in a mixed solution containing sodium hydroxide and ammonium persulfate for reaction, and then taking it out and drying it.

[0015] Among them, those skilled in the art know that the copper substrate is usually pretreated before use. The pretreatment operation can be a conventional operation in the art, generally removing the surface oxide layer and oil stains in sequence. The method for removing the oxide layer can be conventional in the art, for example, the oxide layer can be removed by immersion in dilute hydrochloric acid. The method for removing the oil stain can be conventional in the art, for example, ultrasonic washing can be performed in an alcohol solvent. According to common sense in the art, the copper substrate after removing the oxide layer and oil stains needs to be dried.

[0016] The size of the copper substrate can be conventional in the art, for example, 1×2 cm 2 .

[0017] The reaction time may be conventional in the art, preferably 10 to 15 minutes.

[0018] The mixed solution can be prepared by conventional methods in the art, preferably by the following steps: adding sodium hydroxide solution dropwise to ammonium persulfate solution.

[0019] The concentration of the sodium hydroxide solution may be conventional in the art, generally 5 to 15 mol / L, for example 10 mol / L. The concentration of the ammonium persulfate solution may be conventional in the art, generally 0.15 to 0.2 mol / L, for example 0.18 mol / L.

[0020] The solvent in the sodium hydroxide or ammonium persulfate solution can be a conventional solvent in the art, generally water.

[0021] In step (1), the Cu(OH)2 nanowires are in a nanowire array structure, and the diameter of the nanowires may be 180 to 220 nm, for example, 200 nm.

[0022] In step (1), the copper substrate may be a conventional copper substrate in the art, usually foam copper or copper foil.

[0023] In step (1), the soaking time is preferably 8 to 10 minutes.

[0024] In step (1), the precursor liquid preferably also includes polyvinyl pyrrolidone and a solvent.

[0025] The mass ratio of the trimesic acid, the polyvinyl pyrrolidone and the solvent may be conventional in the art, preferably 1:(7-11):(450-555), for example 1:10:500.

[0026] The solvent may be any conventional solvent in the art, such as water and / or N,N-dimethylformamide, preferably a mixed solvent of water and N,N-dimethylformamide.

[0027] When the solvent is a mixed solvent of water and N,N-dimethylformamide, the mass ratio of the water to the N,N-dimethylformamide is preferably 1: (0.5-1.5), for example 1:1.

[0028] In a preferred embodiment of the present invention, the precursor liquid can be prepared by the following steps: dropping N,N-dimethylformamide into a mixed solution containing trimesic acid, polyvinyl pyrrolidone and water and stirring the mixture evenly.

[0029] In step (1), those skilled in the art know that after the immersion is completed, the HKUST-1 / copper substrate is usually cleaned and dried.

[0030] The cleaning operation may be a conventional operation in the art, usually washing with deionized water and anhydrous ethanol in sequence.

[0031] The drying operation and conditions may be conventional in the art, and the drying is usually performed at 50 to 60° C. for 10 to 12 hours, such as at 60° C. for 12 hours.

[0032] In step (2), the annealing temperature is preferably 430-470°C, more preferably 450°C.

[0033] In step (2), the annealing temperature can be obtained by a conventional heating operation in the art. In the heating operation, the heating rate is preferably 2-4°C / min, more preferably 3°C / min.

[0034] In step (2), the annealing time is preferably 2 to 3 hours, for example 2 hours.

[0035] In step (2), the structure of the CuO-Cu2O@C may be a nanowire array structure, uniformly grown on the surface of the copper substrate. The diameter of the CuO-Cu2O@C may be 270-320 nm, for example, 300 nm.

[0036] The CuO-Cu2O in step (2) is obtained by annealing the copper source in the HKUST-1, and the CuO-Cu2O may be a nanowire array structure.

[0037] In step (3), the Ni3S2 may be a flake structure, uniformly grown on the surface of the C layer.

[0038] The length of the Ni3S2 may be 30-80 nm, for example, 60 nm. The width of the Ni3S2 may be 30-80 nm, for example, 60 nm.

[0039] In step (3), the diameter of the CuO-Cu2O@C@Ni3S2 may be 350 to 500 nm, for example, 400 nm.

[0040] In step (3), the solvent of the electrolyte can be conventional in the art, usually water.

[0041] In step (3), those skilled in the art know that the nickel chloride is usually NiCl2·6H2O.

[0042] In step (3), in the electrolyte, the molar ratio of the nickel chloride to the thiourea can be conventional in the art, preferably 1:(7-37.5), for example 1:20.

[0043] In step (3), it should be noted that if the electrodeposition uses other conventional electrolytes for depositing nickel sulfide in the art, such as nickel nitrate and thioacetamide, the nickel sulfide with a flaky structure in the present invention cannot be obtained.

[0044] In step (3), the concentration of nickel chloride in the electrolyte can be conventional in the art, preferably 0.04 to 0.07 mol·L -1 , for example 0.05 mol·L -1 .

[0045] In step (3), the concentration of thiourea in the electrolyte can be conventional in the art, preferably 0.5 to 1.5 mol·L -1 , for example 1.0 mol·L -1 .

[0046] In step (3), those skilled in the art know that the electrodeposition generally adopts a three-electrode system, in which a platinum sheet is generally used as a counter electrode and silver / silver chloride is used as a reference electrode.

[0047] In step (3), the electrodeposition is preferably cyclic voltammetric electrodeposition.

[0048] In step (3), the voltage range of the electrodeposition can be conventional in the art, preferably -1.2 to 0.2V.

[0049] In step (3), the scan rate of the electrodeposition may be conventional in the art, preferably 5 to 10 mV / s, such as 5 mV / s.

[0050] In step (3), the number of deposition cycles of the electrodeposition is preferably 2 to 4 cycles, more preferably 3 cycles.

[0051] In step (3), those skilled in the art know that the electrodeposition usually includes washing and drying.

[0052] The washing operation may be a conventional operation in the art. Generally, the material after the electrodeposition is taken out and then rinsed with deionized water and anhydrous ethanol in sequence.

[0053] The present invention also provides a composite electrode material, which is prepared by the above-mentioned preparation method.

[0054] The present invention also provides a supercapacitor, whose electrode material is the above-mentioned composite electrode material.

[0055] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0056] The reagents and raw materials used in the present invention are commercially available.

[0057] The positive and progressive effects of the present invention are:

[0058] The present invention screens the raw material components of specific MOFs materials and the preparation process of MOFs materials to obtain HKUST-1 / copper substrate materials, and finally obtains the composite electrode material of the present invention after a specific annealing process and an electrodeposition process. The composite electrode material is a nanowire array structure, and the carbon layer is uniformly coated on the surface of the CuO-Cu2O nanowires, and nickel sulfide grows uniformly and orderly on the surface of the carbon layer. The composite electrode material obtained by combining the above-mentioned process parameters has a large specific surface area and increases the electrochemical sites; it well compensates for the defects of poor conductivity of nickel sulfide and low specific capacitance of carbon materials, reduces the impedance of the electrode material, improves the rate performance under large current, and enables the higher specific capacitance of nickel sulfide itself to be reflected, thereby improving the conductivity of the composite electrode material, and enhancing the electrochemical stability and energy density of the composite electrode material; at the same time, the carbon layer can effectively inhibit the volume expansion of nickel sulfide during charging and discharging, and further enhances the electrochemical stability of the composite electrode material.

[0059] The composite electrode material obtained by the present invention exhibits excellent performance in electrochemical tests, indicating that it has broad application prospects in the field of supercapacitor electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 The XRD diagram of the products obtained in each step of Example 2 is shown in FIG.

[0061] Figure 2 This is a scanning electron microscope image of the composite electrode material in Example 2.

[0062] Figure 3 This is the cyclic voltammetry curve of the composite electrode material in Example 2.

[0063] Figure 4 The composite electrode material in Examples 1, 2, and 3 is 2 mA·cm -1 The constant current discharge curve below.

[0064] Figure 5 This is a constant current discharge curve diagram of the composite electrode material in Example 2 at different current densities. DETAILED DESCRIPTION

[0065] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0066] Example 1

[0067] (1) Preparation of Cu(OH)2 nanowires / copper foam: Weigh 0.913 g of ammonium persulfate in a beaker, add 22 mL of deionized water, and stir magnetically for 30 min until completely dissolved; weigh 3.2 g of sodium hydroxide in a beaker, add 8 mL of deionized water, stir magnetically for 30 min until completely dissolved and the solution is cooled to room temperature. Pour the sodium hydroxide solution into a constant pressure separatory funnel, open the funnel valve and slowly drip it into the ammonium persulfate solution to obtain a mixed solution; let the mixed solution stand for 5 min, and place it in a 1×2 cm 2 The foamed copper was placed in the mixed solution and soaked for 10 min. After its surface turned blue, it was taken out and washed repeatedly with deionized water and anhydrous ethanol for several times, and then placed in a vacuum oven at 60 °C and dried for 12 h.

[0068] Preparation of HKUST-1 / foam copper: Weigh 10 mg of 1,3,5-trimethylbenzene trimesic acid and 100 mg of polyvinyl pyrrolidone in a beaker, add 2.5 mL of deionized water, and then add 2.5 mL of N,N-dimethylformamide dropwise to the solution. After magnetic stirring, a precursor liquid is obtained. The Cu(OH)2 nanowires / foam copper prepared above are placed in the precursor liquid and soaked for 8 min. Then, the prepared Cu(OH)2 nanowires / foam copper are taken out and washed repeatedly with deionized water and anhydrous ethanol for several times, and dried in a vacuum oven at 60°C for 8 h.

[0069] (2) The HKUST-1 / copper foam obtained in step (1) was placed in a porcelain ark and heated in a tubular high-temperature furnace at 3°C ​​min -1 The material was heated to 450°C at a heating rate of 100 °C and kept at that temperature for 2 h. After the material was naturally cooled to room temperature, it was taken out and dried to obtain (CuO-Cu2O@C) / foam copper.

[0070] (3) Weigh 0.005 mol of NiCl2·6H2O and 0.1 mol of thiourea in a beaker, add 100 mL of deionized water, stir magnetically for 30 min until completely dissolved, and obtain an electrolyte for use. A three-electrode system was used for electrodeposition, with (CuO-Cu2O@C) / copper foam as the working electrode, and a platinum sheet and an Ag / AgCl electrode as the counter electrode and reference electrode, respectively. At room temperature, in the above electrolyte, a cyclic voltammetric electrodeposition method was used, with a potential range of -1.2 to 0.2 V and a scan rate of 5 mV s -1 After deposition, the product was taken out with tweezers, then rinsed with deionized water and anhydrous ethanol, and dried to obtain the CuO-Cu2O@C@Ni3S2 / foam copper nanocomposite electrode material.

[0071] Example 2

[0072] In this embodiment, the number of electrodeposition turns is 3 turns, and the remaining preparation process parameters and operation steps are the same as those in Embodiment 1.

[0073] Figure 1 The XRD diagram of the product in each step of this embodiment. The characteristic peaks at 16.7°, 23.8°, 34.1°, 35.9°, 38.2°, 39.8°, and 53.1° correspond to the (020), (021), (002), (111), (041), (130), and (150) crystal planes of Cu(OH)2, respectively; the broad peak near 26° indicates the presence of amorphous carbon in CuO-Cu2O@C and CuO-Cu2O@C@Ni3S2; the characteristic peaks at 21.7°, 31.1°, 37.7°, 50.1°, and 55.1° correspond to the (010), (-110), (111), (-120), and (-121) crystal planes of CuO-Cu2O@C@Ni3S2, respectively. Cu(OH)2 in the figure refers to the Cu(OH)2 nanowire / foam copper obtained in step (1) of this embodiment; HKUST-1 in the figure refers to HKUST-1 / foam copper in step (1) of this embodiment. CuO-Cu2O@C in the figure refers to the (CuO-Cu2O@C) / foam copper prepared in step (2) of this embodiment. CuO-Cu2O@C@Ni3S2 in the figure refers to the composite electrode material finally obtained in this embodiment. The structure of the composite electrode material of this embodiment is as follows: CuO-Cu2O is a nanowire array structure grown on the surface of the foam copper, the C layer is coated on the surface of the CuO-Cu2O nanowires, and Ni3S2 grows uniformly on the surface of the C layer.

[0074] Figure 2 This is a scanning electron microscope image of the composite electrode material prepared in Example 2. It can be seen from the image that the morphology of the composite electrode material in this example is a nanowire array structure, and nickel sulfide grows uniformly and orderly on the surface of the carbon layer.

[0075] The diameter of the Cu(OH)2 nanowire obtained in step (1) of this embodiment is 200nm, and it is a nanowire array structure; the structure of the CuO-Cu2O@C obtained in step (2) is a nanowire array structure, and its diameter is 300nm; the Ni3S2 in the composite electrode material finally obtained is a sheet structure, and the length and width of the sheet structure are 60nm. The diameter of the CuO-Cu2O@C@Ni3S2 nanowire obtained in step (3) is 400nm.

[0076] Example 3

[0077] In this embodiment, the number of electrodeposition turns is 4 turns, and the remaining preparation process parameters and operation steps are the same as those in Embodiment 1.

[0078] Comparative Example 1

[0079] On the basis of Example 2, the preparation operation of HKUST-1 / foam copper in step (1) is not performed to obtain a CuO-Cu2O@Ni3S2 / foam copper nanocomposite electrode material without a carbon layer. The remaining preparation process parameters are the same as those in Example 2.

[0080] Similarly, Chinese patent document CN110504107A also directly electrodeposits nickel sulfide on the copper oxide nanoarray. Similar to the comparative example of the present application, it does not coat the copper oxide nanoarray with a uniform carbon layer, and the cycle stability of the resulting composite electrode material is poor.

[0081] The preparation process parameters of the composite electrode materials of Examples 1 to 3 and Comparative Example 1 are shown in Table 1 below.

[0082] Table 1 Process parameters in Examples 1-3 and Comparative Example 1

[0083]

[0084] The morphology of the composite electrode materials of Examples 2 and 3 of the present invention is the same as that of Example 1, and both are CuO-Cu2O@C@Ni3S2 with a nanowire array structure uniformly grown on the surface of the copper foam. The inventors have discovered through creative work that the composite electrode material of the present invention requires a carbon layer to be uniformly coated on the surface of CuO-Cu2O, and also requires a specific annealing temperature to maintain the array structure of the nanowires in order to achieve the effect of the present invention. When the annealing temperature is lower than 400°C, it cannot be guaranteed that HKUST-1 is completely pyrolyzed and carbonized; and when it is higher than 500°C, it is difficult to maintain the array structure of the nanowires, so the composite electrode material of the present invention cannot be obtained.

[0085] Effect Example 1

[0086] The composite electrode materials obtained in Examples 1 to 3 and Comparative Example 1 were used as working electrodes, platinum sheets were used as counter electrodes, Ag / AgCl electrodes were used as reference electrodes, and the electrolyte was 2 mol·L -1 The electrochemical performance was tested on a Chenhua CHI660E instrument, where the cycling stability was measured at 20 mA cm under the three-electrode system as described above. -2 The data were obtained by testing 4000 cycles of constant current charge and discharge at a current density of . The test results are shown in Table 2 below. The calculation formula for the area specific capacitance in the following embodiments and comparative examples is: C 面积比电容 =(I 即时电流 ×△t 放电时间 ) / (S 工作电极的面积 ×△V 放电电压 ).

[0087] Figure 3The cyclic voltammetry curves of the composite electrode material prepared in Example 2 at different scan rates of 5 to 100 mV are shown. A pair of obvious redox peaks in the figure indicate that the material has good pseudocapacitive properties, and a large area enclosed by the cyclic voltammetry curve indicates that the material has good specific capacitance.

[0088] Figure 4 The composite electrode materials prepared in Examples 1, 2 and 3 are -2 The constant current discharge curve under the above conditions shows that the area specific capacitance of the composite electrode material of Example 2 is 3.152 F·cm -2 .

[0089] Figure 5 The constant current discharge curve of the composite electrode material prepared in Example 2 at different current densities is shown in Table 2. It can be seen from the calculation that the composite electrode material has a constant current discharge curve at 1 mA·cm -2 The area specific capacitance is as high as 3.858F·cm -2 , the rate performance is 67%. It can be seen that the composite electrode material has a high specific capacitance and good rate performance.

[0090] Table 2

[0091]

[0092] As shown in Table 2 above, the composite electrode material of the present invention has a better area specific capacitance. From the calculation formula, it can be seen that the energy density of the present invention is higher.

Claims

1. A method for preparing a composite electrode material, characterized in that: It includes the following steps: (1) Immersing the Cu(OH)2 nanowire / copper substrate in a precursor liquid to obtain HKUST-1 / copper substrate; the organic ligand in the precursor liquid is trimesic acid; the immersion time is 8 to 12 minutes; the precursor liquid also includes the following components: polyvinyl pyrrolidone and a solvent; the preparation method of the Cu(OH)2 nanowire / copper substrate includes the following steps: immersing the copper substrate in a mixed solution containing sodium hydroxide and ammonium persulfate for reaction, and then taking it out and drying it; (2) The HKUST-1 / copper substrate is annealed to obtain a "CuO-Cu2O@C" / copper substrate; the annealing temperature is 400-500°C; (3) Using the "CuO-Cu2O@C" / copper substrate as the working electrode, a "CuO-Cu2O@C@Ni3S2" / copper substrate nanocomposite electrode material is obtained by electrodeposition; the electrolyte in the electrodeposition comprises nickel chloride and thiourea; the electrodeposition is cyclic voltammetric electrodeposition; the voltage range of the electrodeposition is -1.2~0.2V; the scanning rate of the electrodeposition is 5~10mV / s; and the number of deposition cycles of the electrodeposition is 2~4 cycles.

2. The preparation method according to claim 1, characterized in that In step (1), the reaction time is 10 to 15 minutes; And / or, in the mixed solution, the concentration of sodium hydroxide is 5-15 mol / L; And / or, in the mixed solution, the concentration of ammonium persulfate is 0.15-0.2 mol / L; And / or, the copper substrate is foamed copper.

3. The preparation method according to claim 2, characterized in that: In the mixed solution, the concentration of sodium hydroxide is 10 mol / L.

4. The preparation method according to claim 3, characterized in that: In the mixed solution, the concentration of ammonium persulfate is 0.18 mol / L.

5. The preparation method according to claim 1, characterized in that: In step (1), the soaking time is 8 to 10 minutes.

6. The preparation method according to claim 1, characterized in that: The mass ratio of the trimesic acid, the polyvinyl pyrrolidone and the solvent is 1:(7-11):(450-555); And / or, the solvent is water and / or N,N-dimethylformamide.

7. The preparation method according to claim 6, characterized in that: The mass ratio of the trimesic acid, the polyvinyl pyrrolidone and the solvent is 1:10:

500.

8. The preparation method according to claim 6, characterized in that: The solvent is a mixed solvent of water and N,N-dimethylformamide.

9. The preparation method according to claim 8, characterized in that: The mass ratio of the water to the N,N-dimethylformamide is 1:(0.5-1.5).

10. The preparation method according to claim 9, characterized in that: The mass ratio of the water to the N,N-dimethylformamide is 1:

1.

11. The preparation method according to claim 1, characterized in that: In step (2), the annealing temperature is 430-470°C; And / or, in step (2), the heating rate to the annealing temperature is 2-4°C / min; And / or, in step (2), the annealing time is 2 to 3 hours.

12. The preparation method according to claim 11, characterized in that: In step (2), the annealing temperature is 450°C.

13. The preparation method according to claim 11, characterized in that: In step (2), the heating rate to the annealing temperature is 3°C / min.

14. The preparation method according to claim 1, characterized in that: In step (3), the nickel chloride is NiCl2·6H2O; and / or, in the electrolyte, the molar ratio of the nickel chloride to the thiourea is 1:(7-37.5); And / or, in the electrolyte, the concentration of nickel chloride is 0.04-0.07 mol L -1 ; And / or, in the electrolyte, the concentration of thiourea is 0.5-1.5 mol·L -1 .

15. The preparation method according to claim 14, characterized in that: In the electrolyte, the molar ratio of the nickel chloride to the thiourea is 1:

20.

16. The preparation method according to claim 14, characterized in that: In the electrolyte, the concentration of nickel chloride is 0.05 mol L -1 .

17. The preparation method according to claim 14, characterized in that: In the electrolyte, the concentration of thiourea is 1.0 mol·L -1 .

18. The preparation method according to claim 1, characterized in that: The number of deposition turns of the electrodeposition is 3 turns.

19. A composite electrode material, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 18.

20. A supercapacitor, characterized in that: The electrode material of the supercapacitor is the composite electrode material as described in claim 19.

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