Preparation method and application of nickel-cobalt-copper selenide composite MXene / carbon sphere film electrode material

Abstract

This invention belongs to the field of composite electrode materials technology, and relates to a method for preparing a NiCoCu selenide composite MXene / carbon sphere thin film electrode material, comprising: first, dissolving ZIF-67 powder in a carbon sphere solution, then adding an MXene aqueous solution, stirring for 1-10 hours, filtering and drying to obtain ZIF-67@MXene / CS; second, preparing a solution according to the proportion of urea, copper source, nickel source and ethanol, immersing ZIF-67@MXene / CS, and reacting hydrothermally to obtain a NiCoCu-LDH@MXene / CS thin film; third, mixing the NiCoCu-LDH@MXene / CS thin film, selenium powder and sodium borohydride in a mass ratio of 0.5-1:1-2:1-2, reacting at 150-180°C for 12-24 hours, washing the obtained product with deionized water and drying to obtain the final product. MXene and carbon spheres together provide a flexible substrate for the self-supporting material, increasing its conductivity and specific surface area. Simultaneously, NiCoCu-Se intercalation into the MXene acts as an intermediate buffer, preventing MXene self-stabilization and making its structure more stable. When applied as the positive electrode material for supercapacitors, the self-supporting material avoids the use of binders, reducing the material's impedance and improving electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of composite electrode materials technology, and relates to thin film electrodes, particularly to a method for preparing a NiCoCu selenide composite MXene / carbon sphere thin film electrode material and its application. Background Technology

[0002] With the deepening of the global energy transition and the continuous advancement of science and technology, the development of new renewable energy sources and efficient electrochemical energy storage devices has accelerated. Supercapacitors, as one type of electrochemical energy storage device, possess characteristics such as safety, stability, high power density, and fast charge / discharge speed, attracting widespread attention from scientists. However, due to the limited total number of electrolyte ions stored on the electrode surface, the overall energy density of supercapacitors has remained low, hindering their practical application. Therefore, the rational design of electrode materials is crucial for improving the energy density of supercapacitor electrode materials.

[0003] Combining transition metal selenides with highly conductive materials (such as carbon materials or MXene) can not only improve the conductivity of the materials but also enhance their structural stability. Carbon spheres, as a type of carbon material, possess high specific surface area, excellent conductivity, good chemical stability, and mechanical strength. They can remain stable in harsh electrochemical environments, and their morphology, porosity, and composition are easily adjustable to meet diverse application requirements. MXene is a two-dimensional material prepared by etching away the a-layer of the MAX phase, typically using the chemical formula M... n+1 X n T x The term MXene, where M represents an early transition metal, X is a carbon or nitrogen element, and T is a surface functional group (-F, -O, or -OH with a unique two-dimensional structure), is a candidate material for supercapacitor electrode materials due to its unique structure and ion storage properties. It possesses a high specific surface area, tunable functionalized surface ends, good conductivity, and high electrochemical activity, making it ideal as an electrode for supercapacitors. However, like other 2D materials, MXene is a layered transition metal carbonitride, which inevitably recombines during cycling, leading to a significant and rapid decrease in capacity. To prevent MXene self-stabilization, other low-dimensional materials are introduced between the layers as buffers; for example, heterogeneous assembly of MXene with LDH can make their structure more stable. Furthermore, effectively combining transition metal selenides with carbon materials and MXene can improve the conductivity and structural stability of the material, thereby significantly improving its electrochemical performance.

[0004] As shown in the periodic table, selenium (Se) belongs to the same group as oxygen (O) and sulfur (S), and shares some similarities in properties. However, Se has better metallic properties and higher electrical conductivity (1×10⁻⁶) than the latter two. -3 S m-1 ), exceeding O and S (1×10 -5 S m -1 and 5×10 -28 S m -1 Furthermore, compared with transition metal oxides (TMO) and transition metal sulfides (TMS), transition metal selenides (TMSe) have better rate performance and stability. Their excellent conductivity, rich valence state capabilities, good mechanical stability and thermal stability have made them increasingly popular in electronic devices, and they have also been studied and applied in the fields of electronics and optics. Summary of the Invention

[0005] To address the shortcomings of the existing technology, one objective of this invention is to disclose a method for preparing NiCoCu selenide composite MXene / carbon sphere thin film electrode material and its application.

[0006] Technical solution

[0007] With glucose (C6H) 12 Using O6), cobalt salt, 2-methylimidazole (C4H6N2), nickel salt, copper salt, urea (CO(NH2)2), sodium borohydride (NaBH4), selenium powder, and titanium carbide aqueous solution (MXene, 4.5 mg / mL) as raw materials, carbon spheres (CS) were first prepared by hydrothermal method, ZIF-67 was prepared by solution method, and ZIF-67@MXene / CS material was obtained by rapid chemical reaction method. Then, NiCoCu-LDH@MXene / CS was prepared by hydrothermal method, and finally, NiCoCu-Se@MXene / CS thin film electrode material was obtained by high temperature hydrothermal treatment.

[0008] A method for preparing a NiCoCu selenide composite MXene / carbon sphere (NiCoCu-Se@MXene / CS) thin film electrode material includes the following steps:

[0009] A. Dissolve ZIF-67 powder in carbon ball solution, then add MXene aqueous solution, stir for 1-10 h, preferably 6 h, filter and dry to obtain ZIF-67@MXene / CS; wherein, the material ratio of ZIF-67 powder, carbon ball solution and MXene aqueous solution is 10-80 mg: 10-30 mL: 2-10 mL, preferably 50 mg: 20 mL: 5 mL;

[0010] B. Prepare a solution with a material ratio of urea, copper source, nickel source and ethanol of 0.1-0.6g:0.1-0.5mM:0.1-0.5mM:15-30mL, preferably 0.3g:0.3mM:0.3mM:20mL; immerse the above ZIF-67@MXene / CS in the solution and react at 100-120℃ for 1-2h, preferably at 120℃ for 2h. After the reaction vessel has cooled naturally to room temperature, remove the solution, wash it several times with deionized water and anhydrous ethanol, and dry it at 60℃ to obtain NiCoCu-LDH@MXene / CS film.

[0011] C. NiCoCu-LDH@MXene / CS film, selenium powder, and sodium borohydride are mixed in a mass ratio of 0.5–1:1–2:1–2 (preferably 1:1:2) and then heated in an autoclave at 150–180°C.

[0012] The reaction was carried out for 12–24 h, preferably at 180 °C for 24 h. The resulting product was washed with deionized water and dried to obtain NiCoCu-Se@MXene / CS.

[0013] In a preferred embodiment of the present invention, in step A, the ZIF-67 powder is obtained by mixing equal volumes of cobalt salt-methanol solution and 2-methylimidazole-methanol solution, stirring evenly, letting stand for 24 hours, centrifuging, and drying at 60°C. The cobalt salt is Co(NO3)2 or CoCl2. The cobalt salt-methanol solution is prepared by mixing cobalt salt and methanol at a ratio of 1–5 mmol:15–30 mL, preferably 3 mmol:20 mL. The 2-methylimidazole-methanol solution is prepared by mixing 2-methylimidazole and methanol at a material ratio of 0.820–2.46 g:15–30 mL, preferably 1.633 g:20 mL.

[0014] In a preferred embodiment of the present invention, in step A, the carbon ball solution is prepared by dissolving the carbon source in deionized water at a ratio of 3-5g:20-50mL, preferably 4g:40mL, and then reacting the solution hydrothermally at 150-180°C for 4-8 hours, preferably at 160°C for 6 hours. The carbon source is glucose.

[0015] In a preferred embodiment of the present invention, in step A, the MXene aqueous solution is a titanium carbide aqueous solution with a concentration of 4.5 mg / mL.

[0016] In a preferred embodiment of the present invention, in step B, the copper source is Cu(NO3)2 or CuSO4, preferably Cu(NO3)2; the nickel source is Ni(NO3)2 or NiCl2, preferably Ni(NO3)2.

[0017] According to the method described in this invention, the size of the NiCoCu-Se@MXene / CS composite thin film electrode material can be arbitrarily cut according to actual conditions. Under its microscopic state, it can be observed that the NiCoCu-Se polyhedron is composited with MXene / CS, and the polyhedron exhibits a hollow phenomenon.

[0018] Another objective of this invention is to use the prepared NiCoCu-Se@MXene / CS composite thin film electrode material as the positive electrode material of a supercapacitor.

[0019] The prepared NiCoCu-Se@MXene / CS composite thin film electrode material was used as the positive electrode material, with 6 mol L... -1 Using KOH as the electrolyte, activated carbon, conductive carbon black, and binder were uniformly mixed and dispersed in an N-methylpyrrolidone solution at a mass ratio of 8:1:1. This mixture was then coated onto nickel foam, dried, and pressed into an electrode sheet to serve as the negative electrode material for a capacitor. The electrochemical performance of the prepared NiCoCu-Se@MXene / CS composite thin-film electrode material was evaluated through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests in a two-electrode system, and the corresponding energy density and power density were calculated. The voltage range for the cyclic voltammetry (CV) test was 0–0.5 V, and the scan rates were 2, 5, 10, 20, 50, and 100 mV s, respectively. -1 The voltage range for constant current charge-discharge testing is 0–0.5V, and the current density is 1, 2, 3, 5, 8, and 10Ag. -1 .

[0020] The NiCoCu-Se@MXene / CS composite thin film electrode material prepared in this invention was subjected to structural and performance analysis using field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), and a CHI-760E electrochemical workstation to evaluate its electrochemical activity.

[0021] MXene has a unique two-dimensional structure with high specific surface area, adjustable functionalized surface ends, good conductivity and high electrochemical activity. In particular, when combined with transition metal selenides, it can greatly improve the electrochemical performance of the material.

[0022] All reactants and reagents used in this invention are commercially available, including glucose (C6H4O). 12O6), cobalt nitrate hexahydrate (Co(NO3)2·6H2O), 2-methylimidazole (C4H6N2), nickel nitrate hexahydrate (Ni(NO3)2·6H2O), copper nitrate trihydrate (Cu(NO3)2·3H2O), urea (CO(NH2)2), sodium borohydride (NaBH4), selenium powder and titanium carbide aqueous solution (MXene, 4.5 mg / mL).

[0023] Beneficial effects

[0024] This invention synthesizes NiCoCu-Se@MXene / CS composite thin-film electrode materials through three steps: solution method, hydrothermal method, and vacuum filtration method. MXene and carbon spheres together provide a flexible substrate for the self-supporting material, increasing its conductivity and specific surface area. Simultaneously, NiCoCu-Se is intercalated into MXene, acting as an intermediate buffer to prevent MXene self-stabilization and making its structure more stable. Furthermore, when applied as a positive electrode material in supercapacitors, the self-supporting material eliminates the need for binders, reduces the material's impedance, and significantly improves its electrochemical performance. Attached Figure Description

[0025] Figure 1 Scanning electron microscope image of the NiCoCu-Se@MXene / CS composite thin film electrode material prepared in Example 1;

[0026] Figure 2 GCD curves of the NiCoCu-Se@MXene / CS composite thin film electrode material prepared in Example 1;

[0027] Figure 3 Energy density-power density diagram of the supercapacitor assembled from the NiCoCu-Se@MXene / CS composite thin film electrode material prepared in Example 1;

[0028] Figure 4 Cyclic stability diagram of the supercapacitor assembled from the NiCoCu-Se@MXene / CS composite thin film electrode material prepared in Example 1. Detailed Implementation

[0029] The present invention will now be described in detail with reference to embodiments to enable those skilled in the art to better understand the invention, but the invention is not limited to the following embodiments. Unless otherwise specified, the terminology used herein (including technical terms) shall be interpreted as having the same meaning as commonly understood by those skilled in the art to which this invention pertains. It will also be understood that the terminology used herein shall be interpreted as having the same meaning as it has in the context of this specification and related art, and shall not be interpreted in an idealized or excessive manner unless specifically limited herein.

[0030] Example 1

[0031] A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material includes the following steps:

[0032] Step 1: Weigh 3 mmol of Co(NO3)2·6H2O and 1.633 g of 2-methylimidazole and dissolve them separately in 20 mL of methanol. Mix the Co(NO3)2 methanol solution and the 2-methylimidazole solution and stir for 10 minutes. After standing at room temperature for 24 hours, centrifuge and dry at 60 °C to obtain ZIF-67 powder. Weigh 4 g of glucose and dissolve it in 40 mL of deionized water. After hydrothermal reaction at 160 °C for 6 hours, obtain carbon sphere solution. Dissolve 50 mg of the above ZIF-67 powder in 20 mL of carbon sphere solution, add 5 mL of MXene aqueous solution, stir at room temperature for 6 hours, filter and dry to obtain ZIF-67@MXene / CS.

[0033] Step 2: Weigh 0.3g CO(NH2)2, 0.3mmol Cu(NO3)2·3H2O, and 0.3mmol Ni(NO3)2·6H2O and dissolve them in 20mL ethanol. Immerse the prepared ZIF-67@MXene / CS film in the above solution and react at 120℃ for 2h. After the reaction vessel cools to room temperature, take out the sample, wash the sample several times with deionized water and anhydrous ethanol, and dry it at 60℃ to obtain NiCoCu-LDH@MXene / CS film.

[0034] Step 3: Mix NiCoCu-LDH@MXene / CS, selenium powder and sodium borohydride in a mass ratio of 1:1:2 in an autoclave and react at 180℃ for 24 hours. Wash the resulting material with deionized water and dry it to obtain NiCoCu-Se@MXene / CS composite thin film electrode material.

[0035] Characterization and analysis of NiCoCu-Se@MXene / CS composite thin film electrode materials

[0036] like Figure 1 As shown in the figure, in the microscopic state, NiCoCu-Se hollow polyhedra are interspersed in MXene / CS to form a film-like structure with an ultra-high specific surface area.

[0037] like Figure 2 As shown in the figure, the GCD curve of the NiCoCu-Se@MXene / CS composite thin film electrode material can be seen. The results can be calculated for this material at a current density of 1 Ag. -1 It has 1252.3F g at that time -1 High specific capacity.

[0038] like Figure 3 As shown, the NiCoCu-Se@MXene / CS composite thin film electrode material prepared in this embodiment is used as a supercapacitor electrode material in a two-electrode system. The energy density-power density plot shows that the assembled supercapacitor has good power density and energy density, with a power density of 800 W / kg. -1 The maximum energy density achievable at this time is 108.3 Wh / kg. -1 .

[0039] like Figure 4 As shown, the results of the cycle stability test of the NiCoCu-Se@MXene / CS composite thin film electrode material prepared in this embodiment as the positive electrode material of a supercapacitor are shown. After 10,000 cycles, it has a capacity retention rate of 82.4%, which shows good cycle performance.

[0040] Example 2

[0041] A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material includes the following steps:

[0042] Step 1: Weigh 3 mmol of CoCl2·6H2O and 1.633 g of 2-methylimidazole and dissolve them separately in 20 mL of methanol. Mix the CoCl2 methanol solution and the 2-methylimidazole solution and stir for 10 minutes. After standing at room temperature for 24 hours, centrifuge and dry at 60 °C to obtain ZIF-67 powder. Weigh 4 g of glucose and dissolve it in 40 mL of deionized water. After hydrothermal reaction at 160 °C for 6 hours, obtain carbon sphere solution. Dissolve 50 mg of the above ZIF-67 powder in 20 mL of carbon sphere solution, add 5 mL of MXene aqueous solution, stir at room temperature for 6 hours, filter and dry to obtain ZIF-67@MXene / CS.

[0043] Step 2: Weigh 0.3g CO(NH2)2, 0.3mmol CuSO4·5H2O, and 0.3mmol NiCl2·6H2O and dissolve them in 20mL ethanol. Immerse the prepared ZIF-67@MXene / CS film in the above solution and react at 120℃ for 2h. After the reaction vessel cools to room temperature, take out the sample, wash the sample several times with deionized water and anhydrous ethanol, and dry it at 60℃ to obtain NiCoCu-LDH@MXene / CS film.

[0044] Step 3: Mix NiCoCu-LDH@MXene / CS, selenium powder and sodium borohydride in a mass ratio of 1:1:2 in an autoclave and react at 180℃ for 24 hours. Wash the resulting material with deionized water and dry it to obtain NiCoCu-Se@MXene / CS composite thin film electrode material.

[0045] The prepared NiCoCu-Se@MXene / CS composite thin film electrode material was used as the positive electrode material of a supercapacitor. The cycle stability test results showed that after 10,000 cycles, the capacity retention rate was 80.8%, which demonstrated good cycle performance.

[0046] Example 3

[0047] A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material includes the following steps:

[0048] Step 1: Weigh 1 mmol of Co(NO3)2·6H2O and 0.820 g of 2-methylimidazole and dissolve them in 15 mL of methanol respectively. Mix the Co(NO3)2 methanol solution and the 2-methylimidazole solution and stir for 10 minutes. After standing at room temperature for 24 hours, centrifuge and dry at 60 °C to obtain ZIF-67 powder. Weigh 3 g of glucose and dissolve it in 20 mL of deionized water. After hydrothermal reaction at 150 °C for 4 hours, obtain carbon sphere solution. Dissolve 10 mg of the above ZIF-67 powder in 10 mL of carbon sphere solution, add 2 mL of MXene aqueous solution, stir at room temperature for 1 hour, filter and dry to obtain ZIF-67@MXene / CS.

[0049] Step 2: Weigh 0.1 g CO(NH2)2, 0.1 mmol Cu(NO3)2·3H2O, and 0.1 mmol Ni(NO3)2·6H2O and dissolve them in 15 mL ethanol. Immerse the prepared ZIF-67@MXene / CS film in the above solution and react at 120 °C for 2 h. After the reaction vessel cools to room temperature, take out the sample, wash the sample several times with deionized water and anhydrous ethanol, and dry it at 60 °C to obtain NiCoCu-LDH@MXene / CS film.

[0050] Step 3: Mix NiCoCu-LDH@MXene / CS, selenium powder and sodium borohydride in a mass ratio of 1:1:2 in an autoclave and react at 180℃ for 24 hours. Wash the resulting material with deionized water and dry it to obtain NiCoCu-Se@MXene / CS composite thin film electrode material.

[0051] The prepared NiCoCu-Se@MXene / CS composite thin film electrode material was used as the positive electrode material of a supercapacitor. The cycle stability test results showed that after 10,000 cycles, the capacity retention rate was 71.2%, which demonstrated good cycle performance.

[0052] Example 4

[0053] A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material includes the following steps:

[0054] Step 1: Weigh 5 mmol of Co(NO3)2·6H2O and 2.46 g of 2-methylimidazole and dissolve them separately in 30 mL of methanol. Mix the Co(NO3)2 methanol solution and the 2-methylimidazole solution and stir for 10 minutes. After standing at room temperature for 24 hours, centrifuge and dry at 60 °C to obtain ZIF-67 powder. Weigh 5 g of glucose and dissolve it in 50 mL of deionized water. After hydrothermal reaction at 180 °C for 8 hours, obtain carbon sphere solution. Dissolve 80 mg of the above ZIF-67 powder in 30 mL of carbon sphere solution, add 10 mL of MXene aqueous solution, stir at room temperature for 10 hours, filter and dry to obtain ZIF-67@MXene / CS.

[0055] Step 2: Weigh 0.6 g CO(NH2)2, 0.5 mmol Cu(NO3)2·3H2O, and 0.5 mmol Ni(NO3)2·6H2O and dissolve them in 30 mL ethanol. Immerse the prepared ZIF-67@MXene / CS film in the above solution and react at 120 °C for 2 h. After the reaction vessel cools to room temperature, take out the sample, wash the sample several times with deionized water and anhydrous ethanol, and dry it at 60 °C to obtain NiCoCu-LDH@MXene / CS film.

[0056] Step 3: Mix NiCoCu-LDH@MXene / CS, selenium powder and sodium borohydride in a mass ratio of 1:1:2 in an autoclave and react at 180℃ for 24 hours. Wash the resulting material with deionized water and dry it to obtain NiCoCu-Se@MXene / CS composite thin film electrode material.

[0057] The prepared NiCoCu-Se@MXene / CS composite thin film electrode material was used as the positive electrode material of a supercapacitor. The cycle stability test results showed that after 10,000 cycles, the capacity retention rate was 79.6%, which demonstrated good cycle performance.

[0058] Example 5

[0059] A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material includes the following steps:

[0060] Step 1: Weigh 3 mmol of Co(NO3)2·6H2O and 1.633 g of 2-methylimidazole and dissolve them separately in 20 mL of methanol. Mix the Co(NO3)2 methanol solution and the 2-methylimidazole solution and stir for 10 minutes. After standing at room temperature for 24 hours, centrifuge and dry at 60 °C to obtain ZIF-67 powder. Weigh 4 g of glucose and dissolve it in 40 mL of deionized water. After hydrothermal reaction at 160 °C for 6 hours, obtain carbon sphere solution. Dissolve 50 mg of the above ZIF-67 powder in 20 mL of carbon sphere solution, add 5 mL of MXene aqueous solution, stir at room temperature for 6 hours, filter and dry to obtain ZIF-67@MXene / CS.

[0061] Step 2: Weigh 0.3g CO(NH2)2, 0.3mmol Cu(NO3)2·3H2O, and 0.3mmol Ni(NO3)2·6H2O and dissolve them in 20mL ethanol. Immerse the prepared ZIF-67@MXene / CS film in the above solution and react at 120℃ for 1h. After the reaction vessel cools to room temperature, take out the sample, wash the sample several times with deionized water and anhydrous ethanol, and dry it at 60℃ to obtain NiCoCu-LDH@MXene / CS film.

[0062] Step 3: Mix NiCoCu-LDH@MXene / CS, selenium powder and sodium borohydride in a mass ratio of 1:1:2 in an autoclave and react at 180℃ for 24 hours. Wash the resulting material with deionized water and dry it to obtain NiCoCu-Se@MXene / CS.

[0063] The prepared NiCoCu-Se@MXene / CS composite thin film electrode material was used as the positive electrode material of a supercapacitor. The cycle stability test results showed that after 10,000 cycles, it had a capacity retention rate of 77.1%, demonstrating good cycle performance.

[0064] Example 6

[0065] A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material includes the following steps:

[0066] Step 1: Weigh 3 mmol of Co(NO3)2·6H2O and 1.633 g of 2-methylimidazole and dissolve them separately in 20 mL of methanol. Mix the Co(NO3)2 methanol solution and the 2-methylimidazole solution and stir for 10 minutes. After standing at room temperature for 24 hours, centrifuge and dry at 60 °C to obtain ZIF-67 powder. Weigh 4 g of glucose and dissolve it in 40 mL of deionized water. After hydrothermal reaction at 160 °C for 6 hours, obtain carbon sphere solution. Dissolve 50 mg of the above ZIF-67 powder in 20 mL of carbon sphere solution, add 5 mL of MXene aqueous solution, stir at room temperature for 6 hours, filter and dry to obtain ZIF-67@MXene / CS.

[0067] Step 2: Weigh 0.3g CO(NH2)2, 0.3mmol Cu(NO3)2·3H2O, and 0.3mmol Ni(NO3)2·6H2O and dissolve them in 20mL ethanol. Immerse the prepared ZIF-67@MXene / CS film in the above solution and react at 120℃ for 2h. After the reaction vessel cools to room temperature, take out the sample, wash the sample several times with deionized water and anhydrous ethanol, and dry it at 60℃ to obtain NiCoCu-LDH@MXene / CS film.

[0068] Step 3: Mix NiCoCu-LDH@MXene / CS, selenium powder and sodium borohydride in a mass ratio of 0.5:2:2 in an autoclave and react at 180℃ for 24h. Wash the resulting material with deionized water and dry it to obtain NiCoCu-Se@MXene / CS.

[0069] The prepared NiCoCu-Se@MXene / CS composite thin film electrode material was used as the positive electrode material of a supercapacitor. The cycle stability test results showed that after 10,000 cycles, it had a capacity retention rate of 76.5%, demonstrating good cycle performance.

[0070] Example 7

[0071] A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material includes the following steps:

[0072] Step 1: Weigh 3 mmol of Co(NO3)2·6H2O and 1.633 g of 2-methylimidazole and dissolve them separately in 20 mL of methanol. Mix the Co(NO3)2 methanol solution and the 2-methylimidazole solution and stir for 10 minutes. After standing at room temperature for 24 hours, centrifuge and dry at 60 °C to obtain ZIF-67 powder. Weigh 4 g of glucose and dissolve it in 40 mL of deionized water. After hydrothermal reaction at 160 °C for 6 hours, obtain carbon sphere solution. Dissolve 50 mg of the above ZIF-67 powder in 20 mL of carbon sphere solution, add 5 mL of MXene aqueous solution, stir at room temperature for 6 hours, filter and dry to obtain ZIF-67@MXene / CS.

[0073] Step 2: Weigh 0.3g CO(NH2)2, 0.3mmol Cu(NO3)2·3H2O, and 0.3mmol Ni(NO3)2·6H2O and dissolve them in 20mL ethanol. Immerse the prepared ZIF-67@MXene / CS film in the above solution and react at 120℃ for 2h. After the reaction vessel cools to room temperature, take out the sample, wash the sample several times with deionized water and anhydrous ethanol, and dry it at 60℃ to obtain NiCoCu-LDH@MXene / CS film.

[0074] Step 3: Mix NiCoCu-LDH@MXene / CS, selenium powder and sodium borohydride in a mass ratio of 1:1:1 in an autoclave and react at 180℃ for 24 hours. Wash the resulting material with deionized water and dry it to obtain NiCoCu-Se@MXene / CS.

[0075] The prepared NiCoCu-Se@MXene / CS composite thin film electrode material was used as the positive electrode material of a supercapacitor. The cycle stability test results showed that after 10,000 cycles, the capacity retention rate was 72.4%, which demonstrated good cycle performance.

[0076] Example 8

[0077] A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material includes the following steps:

[0078] Step 1: Weigh 3 mmol of Co(NO3)2·6H2O and 1.633 g of 2-methylimidazole and dissolve them separately in 20 mL of methanol. Mix the Co(NO3)2 methanol solution and the 2-methylimidazole solution and stir for 10 minutes. After standing at room temperature for 24 hours, centrifuge and dry at 60 °C to obtain ZIF-67 powder. Weigh 4 g of glucose and dissolve it in 40 mL of deionized water. After hydrothermal reaction at 160 °C for 6 hours, obtain carbon sphere solution. Dissolve 50 mg of the above ZIF-67 powder in 20 mL of carbon sphere solution, add 5 mL of MXene aqueous solution, stir at room temperature for 6 hours, filter and dry to obtain ZIF-67@MXene / CS.

[0079] Step 2: Weigh 0.3g CO(NH2)2, 0.3mmol Cu(NO3)2·3H2O, and 0.3mmol Ni(NO3)2·6H2O and dissolve them in 20mL ethanol. Immerse the prepared ZIF-67@MXene / CS film in the above solution and react at 120℃ for 2h. After the reaction vessel cools to room temperature, take out the sample, wash the sample several times with deionized water and anhydrous ethanol, and dry it at 60℃ to obtain NiCoCu-LDH@MXene / CS film.

[0080] Step 3: Mix NiCoCu-LDH@MXene / CS, selenium powder and sodium borohydride in a mass ratio of 1:1:2 in an autoclave and react at 150°C for 24 hours. Wash the resulting material with deionized water and dry it to obtain NiCoCu-Se@MXene / CS.

[0081] The prepared NiCoCu-Se@MXene / CS composite thin film electrode material was used as the positive electrode material of a supercapacitor. The cycle stability test results showed that after 10,000 cycles, the capacity retention rate was 70.1%, which demonstrated good cycle performance.

[0082] Example 9

[0083] A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material includes the following steps:

[0084] Step 1: Weigh 3 mmol of Co(NO3)2·6H2O and 1.633 g of 2-methylimidazole and dissolve them separately in 20 mL of methanol. Mix the Co(NO3)2 methanol solution and the 2-methylimidazole solution and stir for 10 minutes. After standing at room temperature for 24 hours, centrifuge and dry at 60 °C to obtain ZIF-67 powder. Weigh 4 g of glucose and dissolve it in 40 mL of deionized water. After hydrothermal reaction at 160 °C for 6 hours, obtain carbon sphere solution. Dissolve 50 mg of the above ZIF-67 powder in 20 mL of carbon sphere solution, add 5 mL of MXene aqueous solution, stir at room temperature for 6 hours, filter and dry to obtain ZIF-67@MXene / CS.

[0085] Step 2: Weigh 0.3g CO(NH2)2, 0.3mmol Cu(NO3)2·3H2O, and 0.3mmol Ni(NO3)2·6H2O and dissolve them in 20mL ethanol. Immerse the prepared ZIF-67@MXene / CS film in the above solution and react at 120℃ for 2h. After the reaction vessel cools to room temperature, take out the sample, wash the sample several times with deionized water and anhydrous ethanol, and dry it at 60℃ to obtain NiCoCu-LDH@MXene / CS film.

[0086] Step 3: Mix NiCoCu-LDH@MXene / CS, selenium powder and sodium borohydride in a mass ratio of 1:1:2 in an autoclave and react at 180℃ for 12 hours. Wash the resulting material with deionized water and dry it to obtain NiCoCu-Se@MXene / CS.

[0087] The prepared NiCoCu-Se@MXene / CS composite thin film electrode material was used as the positive electrode material of a supercapacitor. The cycle stability test results showed that after 10,000 cycles, the capacity retention rate was 71.6%, which demonstrated good cycle performance.

[0088] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a NiCoCu selenide composite MXene / carbon sphere thin-film electrode material, characterized in that, Includes the following steps: A. Dissolve ZIF-67 powder in carbon ball solution, then add MXene aqueous solution, stir for 1-10 hours, filter and dry to obtain ZIF-67@MXene / CS; wherein, the material ratio of ZIF-67 powder, carbon ball solution and MXene aqueous solution is 10-80 mg: 10-30 mL: 2-10 mL; B. Prepare a solution by mixing urea, copper source, nickel source and ethanol in a ratio of 0.1-0.6g: 0.1-0.5mmol: 0.1-0.5mmol: 15-30mL, immerse the solution in the ZIF-67@MXene / CS solution, react at 100-120℃ for 1-2 hours, remove the solution after the reaction vessel has cooled to room temperature, wash it several times with deionized water and anhydrous ethanol, and dry it at 60℃ to obtain the NiCoCu-LDH@MXene / CS film. C. Mix NiCoCu-LDH@MXene / CS film, selenium powder and sodium borohydride in a mass ratio of 0.5~1:1~2:1~2 and react them in an autoclave at 150~180℃ for 12~24h. The resulting product is washed with deionized water and dried.

2. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 1, characterized in that: In step A, ZIF-67 powder is dissolved in carbon ball solution, and then MXene aqueous solution is added. After stirring for 6 hours, ZIF-67@MXene / CS is obtained by filtration and drying. The material ratio of ZIF-67 powder, carbon ball solution and MXene aqueous solution is 50mg: 20mL: 5mL.

3. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 1, characterized in that: In step A, the ZIF-67 powder is obtained by mixing equal volumes of cobalt salt-methanol solution and 2-methylimidazole-methanol solution, stirring evenly, letting stand for 24 hours, centrifuging, and drying at 60°C. The cobalt salt is Co(NO3)2 or CoCl2.

4. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 3, characterized in that: In step A, the cobalt salt-methanol solution is prepared by mixing cobalt salt and methanol at a ratio of 1~5 mmol: 15~30 mL.

5. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 4, characterized in that: In step A, the cobalt salt-methanol solution is prepared by mixing cobalt salt and methanol at a ratio of 3 mmol: 20 mL.

6. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 3, characterized in that: In step A, the 2-methylimidazole-methanol solution is prepared by mixing 2-methylimidazole and methanol in a material ratio of 0.820~2.46g: 15~30mL.

7. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 6, characterized in that: In step A, the 2-methylimidazole-methanol solution is a mixture of 2-methylimidazole and methanol in a material ratio of 1.633g:20mL.

8. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 1, characterized in that: In step A, the carbon ball solution is prepared by dissolving a carbon source in deionized water at a ratio of 3~5g: 20~50mL and then reacting it hydrothermally at 150~180℃ for 4~8h. The carbon source is glucose.

9. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 8, characterized in that: In step A, the carbon ball solution is prepared by dissolving the carbon source in deionized water at a ratio of 4g:40mL and then reacting it hydrothermally at 160℃ for 6 hours.

10. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 1, characterized in that: In step A, the MXene aqueous solution is a titanium carbide aqueous solution with a concentration of 4.5 mg / mL.

11. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 1, characterized in that: In step B, a solution was prepared according to the material ratio of urea, copper source, nickel source and ethanol as 0.3g: 0.3mmol: 0.3mmol: 20mL; the solution was immersed in the above ZIF-67@MXene / CS and reacted at 120℃ for 2 h. After the reaction vessel was naturally cooled to room temperature, it was taken out.

12. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 1, characterized in that: In step B, the copper source is Cu(NO3)2 or CuSO4, and the nickel source is Ni(NO3)2 or NiCl2.

13. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 12, characterized in that: In step B, the copper source is Cu(NO3)2 and the nickel source is Ni(NO3)2.

14. The method for preparing the NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 1, characterized in that: In step C, NiCoCu-LDH@MXene / CS film, selenium powder and sodium borohydride are mixed in a mass ratio of 1:1:2 and reacted in an autoclave at 180°C for 24 hours. The resulting product is washed with deionized water and dried.

15. The NiCoCu selenide composite MXene / carbon sphere thin film electrode material prepared by any one of the methods described in claims 1-14.

16. The NiCoCu selenide composite MXene / carbon sphere thin film electrode material according to claim 15, characterized in that: Its microstructure consists of NiCoCu-Se polyhedra combined with MXene / CS, with hollow structures appearing in the polyhedra.

17. An application of the NiCoCu selenide composite MXene / carbon sphere thin film electrode material as described in claim 15 or 16, characterized in that: It is used as the positive electrode material for supercapacitors.

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