Nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material and preparation method thereof

Abstract

The invention relates to the technical field of electrochemical materials, in particular to a nitrogen-doped nickel-cobalt hydroxide / MoS2 composite electrode material and a preparation method thereof. The preparation method comprises the following steps: mixing cobalt salt, nickel salt, hexadecyl trimethyl ammonium bromide, an organic solvent and deionized water to obtain a reaction solution; adding MoS2 nanosheets into the reaction solution under ultrasonic dispersion and mechanical stirring to form a mixed solution, and reacting in a reaction kettle; and after the reaction is finished, standing and aging, and treating to obtain the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material. According to the method disclosed by the invention, the hexadecyl trimethyl ammonium bromide is introduced as a surfactant, and the raw material ratio, the reaction condition and the precipitation process are accurately controlled, so that the prepared nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material has high specific capacitance and excellent cycling stability, and is suitable for being used as a supercapacitor electrode material.

Description

Technical Field

[0001] This invention relates to the field of electrochemical materials technology, specifically to a nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material and its preparation method. Background Technology

[0002] With the increasing demand for the synergistic development of high power density and high energy density in electrochemical energy storage technology, supercapacitors have become a research focus due to their unique charge storage mechanism. However, traditional electrode materials (such as carbon materials and conductive polymers) are limited by their low specific capacitance, while transition metal hydroxides, although possessing advantages such as high theoretical specific capacitance and low cost, are often limited in practical applications due to poor conductivity, insufficient structural stability, and difficulty in morphology control. To overcome this bottleneck, researchers have proposed modifying materials through heterostructure composites and heteroatom doping strategies. Among these, two-dimensional transition metal sulfides (such as MoS2) can provide efficient ion transport channels due to their layered structure, while nitrogen (N) atom doping can optimize the electronic state density of the material and introduce pseudocapacitive active sites. The synergistic effect of these two approaches can significantly improve the electrochemical performance of the composite material.

[0003] While composite strategies have shown great potential in improving electrode material performance, existing material systems still face key challenges: the low electronic conductivity of single-component hydroxides leads to actual specific capacitance far lower than theoretical values; the materials are prone to volume expansion / contraction during charge / discharge, resulting in active material shedding or structural collapse, significantly reducing cycle life. Furthermore, traditional synthesis methods struggle to precisely control the microstructure and crystal phase structure of the products, affecting the uniformity of electrochemical performance.

[0004] Based on this, the present invention constructs a composite structure of nitrogen-doped nickel cobalt hydroxide and MoS2, combining the advantages of both components to achieve a comprehensive improvement in the material's conductivity, structural stability, and electrochemical activity, providing an innovative solution for the development of high-performance supercapacitors. Summary of the Invention

[0005] The purpose of this invention is to provide a nitrogen-doped nickel cobalt hydroxide / MoS2 composite material and its preparation method. By precisely controlling the synthesis process, the nitrogen-doped nickel cobalt hydroxide / MoS2 composite material is prepared with high quality and high yield. The prepared composite material exhibits high specific capacitance and good cycle stability, and is suitable for supercapacitor electrode materials, providing a new solution for improving the performance of supercapacitors.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material includes the following steps: S1: A reaction solution is obtained by mixing cobalt salt, nickel salt, hexadecyltrimethylammonium bromide, organic solvent and deionized water; S2: MoS2 nanosheets are added to the reaction solution under ultrasonic dispersion and mechanical stirring to form mixture C; mixture C is transferred to a reaction vessel for reaction. S3: After the reaction is complete, allow it to stand and age; then vacuum filter, wash and dry the aged precipitate to obtain the final nitrogen-doped nickel cobalt hydroxide / MoS2 composite material.

[0007] Further, in step S1, the cobalt salt is cobalt acetate, the nickel salt is nickel acetate, and the mass ratio of cobalt acetate to nickel acetate is 1:0.5-2.

[0008] Further, in step S1, the organic solvent is N,N-dimethylformamide, and the mass ratio of cobalt acetate to N,N-dimethylformamide is 1:500-800.

[0009] Further, in step S1, the mass ratio of hexadecyltrimethylammonium bromide to deionized water is 1:5000-10000, and the mass ratio of cobalt acetate to hexadecyltrimethylammonium bromide is 10:1-3.

[0010] Furthermore, in step S2, the mass ratio of cobalt acetate to MoS2 nanosheets is 10:1.6-3.2, the ultrasonic dispersion power is 500-800 W, the mechanical stirring speed is 300-800 rpm / min, and the stirring time is 2-5 hours.

[0011] Furthermore, in step S2, the reaction temperature is 120-240℃ and the reaction time is 6-24 hours.

[0012] Further, step S1 includes the following steps: S11 Preparation of Mixture A: Cobalt acetate and nickel acetate are weighed into N,N-dimethylformamide to form mixture A; S12 Preparation of Mixture B: Mix hexadecyltrimethylammonium bromide with deionized water to form mixture B; S13 Preparation of reaction solution: Mixture B and mixture A are mixed under ultrasonic dispersion and mechanical stirring to form a reaction solution.

[0013] Furthermore, in step S13, the ultrasonic dispersion power is 500-800 W, the mechanical stirring speed is 300-800 rpm / min, and the stirring treatment time is 10-30 hours.

[0014] Furthermore, steps S11 and S12 include ultrasonic dispersion and mechanical stirring.

[0015] Furthermore, in step S11, the ultrasonic dispersion power is 500-1000 W, the mechanical stirring speed is 400-1000 rpm / min, and the processing time is 5-24 hours.

[0016] Furthermore, in step S12, the ultrasonic dispersion power is 500-1000 W, the mechanical stirring speed is 400-1000 rpm / min, and the stirring time is 5-24 hours.

[0017] The present invention also discloses a nitrogen-doped nickel cobalt hydroxide / MoS2 composite material prepared according to the above method.

[0018] Furthermore, the composite material exhibits a sheet-like stacked structure.

[0019] This invention further discloses the application of the above-mentioned nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material in the preparation of supercapacitor electrodes.

[0020] Furthermore, the charge / discharge capacity of nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material as a supercapacitor electrode can reach up to 856.2 F / g.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses hexadecyltrimethylammonium bromide (CTAB) as a surfactant. On the one hand, it improves the surface tension of the solution and promotes the uniform formation of precipitates, providing a more favorable environment for subsequent liquid phase reactions. On the other hand, the quaternary ammonium cation of CTAB serves as a nitrogen source and interacts electrostatically with nickel and cobalt ions in the liquid phase reaction to form coordination or adsorption, thereby resulting in the doping of a small amount of nitrogen. (2) By introducing nitrogen into the composite material, the present invention can not only optimize the electronic state density of the material and improve the conductivity of the material, but also increase the pseudocapacitive active sites, thereby increasing the specific capacitance of the material, so that the composite material exhibits higher storage capacity in supercapacitor applications. (3) The molybdenum disulfide nanosheets of the present invention provide a uniform growth template for the growth of nickel cobalt hydroxide, and the amphiphilic adsorption layer formed by CTAB on the surface of MoS2 acts as a molecular bridge. Its exposed cationic head groups attract negatively charged metal hydroxide precursor species (such as hydroxyl complexes) through electrostatic interaction, promoting the uniform nucleation and orderly arrangement of nickel cobalt hydroxide on the surface of MoS2, and constructing a three-dimensional sheet stacked structure. When used as a supercapacitor electrode, this structure can increase the effective contact area with the electrolyte, provide more reactive sites for electrolyte ions, and thus improve the electrochemical performance of the entire electrode. (4) By precisely controlling the raw material ratio, reaction conditions and precipitation process, this invention has achieved the synthesis of high-quality and high-yield nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material. At the same time, the liquid-phase reaction accelerates the reaction process and improves the crystallinity and purity of the product. This method is applicable to the synthesis of nickel-cobalt mixed hydroxides with different molar ratios, providing a new idea for the development of electrode materials. Attached Figure Description

[0022] Figure 1 SEM image of the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared in Example 1; Figure 2 The charge-discharge curve of the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared in Example 1; Figure 3 Cyclic voltammetry curves of the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared in Example 1; Figure 4 The image shows the AC impedance test results of the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared in Example 1. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and embodiments: As used herein, unless otherwise specified, numerical ranges include both the start and end values ​​of the range. For example, when describing a mass ratio as "1:500-800", this means that both 1:500 and 1:800 are valid values ​​for that mass ratio.

[0024] Unless otherwise stated, all materials, reagents, and apparatus used in this invention are commercially available products.

[0025] In a first aspect, the synthesis method of the nitrogen-doped nickel cobalt hydroxide / MoS2 composite material of the present invention, by precisely controlling the raw material ratio, reaction conditions and precipitation process, combined with the auxiliary effect of the surfactant cetyltrimethylammonium bromide (CTAB), develops a high-quality, high-yield nitrogen-doped nickel cobalt hydroxide / MoS2 composite material. This material exhibits high specific capacitance and good cycle stability, providing a new solution for improving the performance of supercapacitors.

[0026] Specifically, in this invention, there are no special restrictions on cobalt salts and nickel salts in step S1, as long as they can dissolve in the selected organic solvent. Preferably, acetates, namely cobalt acetate and nickel acetate, are used in step S1. Therefore, the acetates first form an acetate coordination compound during the reaction process, and then react with other substances to form a coordination chelate.

[0027] In step S1, there are no special restrictions on the organic solvent; amines, alcohols, etc., can all be used. N,N-dimethylformamide (DMF) is preferred.

[0028] In order to form a homogeneous reaction solution, step S1 in this invention includes the following steps: S11 Preparation of Mixture A: Cobalt acetate and nickel acetate are weighed into N,N-dimethylformamide to form mixture A; S12 Preparation of Mixture B: Mix hexadecyltrimethylammonium bromide with deionized water to form mixture B; S13 Preparation of reaction solution: Mixture B and mixture A are mixed under ultrasonic dispersion and mechanical stirring to form a reaction solution.

[0029] In step S11, the mass ratio of cobalt acetate, nickel acetate, and the solvent N,N-dimethylformamide (DMF) needs to be strictly controlled to obtain an optimized final product. Preferably, the mass ratio of cobalt acetate to nickel acetate is 1:0.5-2, and the mass ratio of cobalt acetate to N,N-dimethylformamide is 1:500-800.

[0030] Furthermore, in step S11, to ensure uniform mixing of the raw materials in the solvent, ultrasonic dispersion and mechanical stirring are applied during the mixing process to guarantee that the raw material molecules achieve complete dissolution and uniform dispersion in the solvent. In this invention, there are no particular limitations on the conditions for ultrasonic dispersion and mechanical stirring. However, preferably, the ultrasonic dispersion power is 500-1000 W, the mechanical stirring speed is 400-1000 rpm / min, and the processing time is 5-24 hours. As described in the following examples, the final product obtained under these conditions exhibits the best performance.

[0031] In this invention, cetyltrimethylammonium bromide (CTAB) is used as a surfactant in step S12. The addition of CTAB as a surfactant improves the surface tension of the solution, facilitating better dissolution and dispersion of the raw material molecules in the solvent, thus providing a more favorable environment for subsequent liquid-phase reactions. Simultaneously, it promotes the uniform nucleation of nickel-cobalt hydroxide on the molybdenum disulfide sheets, thereby optimizing the microstructure and properties of the composite product and indirectly improving the structural stability of the final composite material. Furthermore, the quaternary ammonium salt of CTAB serves as a source of nitrogen in the final composite material.

[0032] Preferably, the mass ratio of hexadecyltrimethylammonium bromide to deionized water is 1:5000-10000.

[0033] Similar to step S11, in step S12, to ensure uniform mixing of the raw materials in the solvent, ultrasonic dispersion and mechanical stirring are applied during the mixing process. Preferably, the ultrasonic dispersion power is 500-1000 W, the mechanical stirring speed is 400-1000 rpm / min, and the stirring time is 5-24 hours.

[0034] In this invention, in step S13, the stirring speed and ultrasonic power need to be strictly controlled to avoid aggregation caused by local overheating or excessive stirring of the solution. Preferably, the ultrasonic dispersion power is 500-800 W, the mechanical stirring speed is 300-800 rpm / min, and the stirring time is 10-30 hours.

[0035] In step S13, the mass ratio of cobalt acetate in mixture A to hexadecyltrimethylammonium bromide in mixture B is 10:1-3 to optimize the performance of the final material.

[0036] In this invention, in step S2, the reaction solution is mixed with MoS2 nanosheets for subsequent reactions. The mixing of the reaction solution and MoS2 nanosheets requires that the mass ratio of cobalt acetate to MoS2 nanosheets in the reaction solution be 10:1.6-3.2. During the mixing process, a homogeneous reaction solution is obtained by ultrasonic dispersion and mechanical stirring. Preferably, the ultrasonic dispersion power is 500-800W, the mechanical stirring speed is 300-800 rpm / min, and the stirring time is 2-5 hours.

[0037] Step S2 involves a liquid-phase reaction. During the reaction, the MoS2 nanosheets provide a lamellar attachment surface and a directional growth template for the growth of nickel-cobalt hydroxide, promoting the uniform nucleation and orderly arrangement of nickel-cobalt hydroxide along the lamellar axis on the MoS2 surface, guiding the composite material towards a three-dimensional lamellar stacked structure. When used as a supercapacitor electrode, this three-dimensional lamellar stacked structure can increase the effective contact area with the electrolyte, providing more reactive sites for electrolyte ions, thereby improving the overall electrochemical performance of the electrode.

[0038] Preferably, in step S2, the reaction temperature is 120-240℃ and the reaction time is 6-24 hours.

[0039] In the liquid-phase reaction of step S2, nickel acetate and cobalt acetate dissociate in the solvent to form Ni. 2+ and Co 2+ Ions, these metal ions with quaternary ammonium cations of CTAB (C 16 H 33 N + (CH3)3 +Electrostatic interactions occur, leading to coordination or adsorption, resulting in the doping of small amounts of nitrogen. Doping with small amounts of nitrogen can optimize the electronic density of states of the material, improve its conductivity, increase pseudocapacitive active sites, and increase its specific capacitance, thus enabling the composite material to exhibit higher storage capacity in supercapacitor applications.

[0040] Step S3 is a process that further promotes the maturation and crystallization of the precipitate in order to improve the structural stability and electrochemical performance of the precipitate.

[0041] Specifically, step S3 includes aging the precipitate overnight after the reaction, vacuum filtering the precipitate, washing it three times with deionized water and ethanol respectively to remove impurities and unreacted raw materials adhering to the surface of the precipitate, and drying the washed precipitate in an oven at 60°C to obtain the final nitrogen-doped nickel cobalt hydroxide / MoS2 composite material.

[0042] Preferably, the preparation method of the present invention includes the following steps: S11 Preparation of Mixture A: Cobalt acetate and nickel acetate are weighed into N,N-dimethylformamide and treated by ultrasonic dispersion and mechanical stirring to form mixture A; S12 Preparation of Mixture B: Hexadecyltrimethylammonium bromide and deionized water are mixed under ultrasonic dispersion and mechanical stirring to form Mixture B; S13 Preparation of reaction solution: Mixture B and mixture A are mixed under ultrasonic dispersion and mechanical stirring to form a reaction solution; S2 Introduction of MoS2: MoS2 nanosheets are added to the reaction solution obtained in step S13 under ultrasonic dispersion and mechanical stirring to form a mixture C; S3 Aging and Post-treatment: The mixture C is transferred to the reactor for reaction. After the reaction is completed, it is aged by standing overnight. The aged precipitate is then vacuum filtered, washed, and dried to obtain the final nitrogen-doped nickel cobalt hydroxide / MoS2 composite material.

[0043] This invention prepares a nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material with high specific capacitance and excellent cycle stability by combining a surfactant with MoS2. Specifically, the mechanism of action of the combination of the CTAB surfactant and MoS2 in this invention is as follows: Effects of CTAB on the morphology and dispersion of single components 1. Micelle guidance and morphology control: CTAB self-assembles into micelles in the aqueous phase, which serve as soft templates to guide the directional growth of nickel cobalt hydroxide precursors, inhibit random aggregation, and promote the formation of highly dispersed one-dimensional or sheet-like nanostructures; its quaternary ammonium salt cation head groups adsorb onto the hydroxide surface, imparting a positive charge and enhancing colloidal stability.

[0044] 2. MoS2 surface modification and dispersion: The hydrophobic segments of CTAB are adsorbed onto the surface of MoS2 nanosheets through hydrophobic interactions, with the hydrophilic cation head groups facing outwards, which significantly improves its hydrophilicity and dispersion stability in the aqueous phase and inhibits stacking.

[0045] CTAB's core role in interface connectivity 1. Enhanced Interfacial Coupling: The amphiphilic adsorption layer formed by CTAB on the MoS2 surface acts as a molecular bridge. Its exposed cationic head groups attract negatively charged metal hydroxide precursor species (such as hydroxyl complexes) through electrostatic interactions, effectively promoting preferential heterogeneous nucleation and epitaxial growth of hydroxides on the MoS2 surface. Simultaneously, the tight physical contact mediated by CTAB facilitates the formation of metal ions (Ni... 2+ and Co 2+ The strong interfacial interactions (such as MO-Mo / S bonds) between the ions and the coordinated unsaturated sulfur / molybdenum atoms at the edge of MoS2 create favorable conditions, significantly enhancing the interfacial bonding strength and charge transport efficiency between the two phases.

[0046] In a second aspect, the present invention provides a nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared according to the above method. During the preparation of this composite material, MoS2 nanosheets are used as growth templates, and nickel-cobalt hydroxide is uniformly nucleated and orderly arranged along the axial direction of the MoS2 sheets, ultimately resulting in a composite material with a sheet-like stacked structure.

[0047] In a third aspect, the present invention provides the application of the above-mentioned material as a supercapacitor electrode, with a charge / discharge capacity of up to 856.2 F / g.

[0048] The technical solution of the present invention is further described in detail below through embodiments: Example 1 S11 Preparation of Mixture A: Weigh 100 mg of cobalt acetate and 50 mg of nickel acetate, add them to 50 g of N,N-dimethylformamide, ultrasonically disperse at 1000 W power for 24 hours, and mechanically stir at 1000 rpm / min to ensure that the raw materials are completely dissolved and uniformly dispersed to form Mixture A.

[0049] S12 Preparation of Mixture B: Weigh 20 mg of cetyltrimethylammonium bromide and mix with 200 g of deionized water, ultrasonically disperse at 1000 W power for 24 hours, and mechanically stir at 1000 rpm / min to prepare Mixture B.

[0050] S13 Preparation of reaction solution: Slowly add mixture B to mixture A, ultrasonically disperse at 800 W power, and mechanically stir at 600 rpm / min for 20 hours to form a uniform reaction solution.

[0051] S2 Introduction of MoS2: 16 mg of MoS2 nanosheets were added to the above homogeneous reaction solution, ultrasonically dispersed at 800 W power, and mechanically stirred at 600 rpm / min for 3 hours to obtain a mixed reaction solution; then, the mixed reaction solution was transferred to a reaction vessel and subjected to liquid phase reaction at 200 °C for 24 hours.

[0052] S3 Aging and Post-treatment: After the reaction was completed, the mixture was aged overnight. The aged precipitate was then vacuum filtered, washed three times each with deionized water and ethanol, and dried in an oven at 60°C to obtain the final nitrogen-doped nickel cobalt hydroxide / MoS2 composite material.

[0053] Example 2 S11 Preparation of Mixture A: Weigh 100 mg of cobalt acetate and 100 mg of nickel acetate, add them to 60 g of N,N-dimethylformamide, ultrasonically disperse at 500 W power for 12 hours, and mechanically stir at 400 rpm / min to ensure that the raw materials are completely dissolved and uniformly dispersed to form Mixture A.

[0054] S12 Preparation of Mixture B: Weigh 10 mg of cetyltrimethylammonium bromide and mix with 100 g of deionized water, ultrasonically disperse at 500 W power for 12 hours, and mechanically stir at 400 rpm / min to prepare Mixture B.

[0055] S13 Preparation of reaction solution: Slowly add mixture B to mixture A, ultrasonically disperse at 500 W power, and mechanically stir at 300 rpm / min for 15 hours to form a uniform reaction solution.

[0056] S2 Introduction of MoS2: 24 mg of MoS2 nanosheets were added to the above homogeneous reaction solution, ultrasonically dispersed at 500 W power, and mechanically stirred at 300 rpm / min for 2 hours to obtain a mixed reaction solution; then, the mixed reaction solution was transferred to a reaction vessel and subjected to liquid phase reaction at 180 °C for 12 hours.

[0057] S3 Aging and Post-treatment: After the reaction was completed, the mixture was aged overnight. The aged precipitate was then vacuum filtered, washed three times each with deionized water and ethanol, and dried in an oven at 60°C to obtain the final nitrogen-doped nickel cobalt hydroxide / MoS2 composite material.

[0058] Example 3 S11 Preparation of Mixture A: Weigh 100 mg of cobalt acetate and 150 mg of nickel acetate, add them to 70 g of N,N-dimethylformamide, ultrasonically disperse at 800 W power for 20 hours, and mechanically stir at 800 rpm / min to ensure that the raw materials are completely dissolved and uniformly dispersed to form Mixture A.

[0059] S12 Preparation of Mixture B: Weigh 30 mg of cetyltrimethylammonium bromide and mix with 150 g of deionized water, ultrasonically disperse at 800 W power for 20 hours, and mechanically stir at 800 rpm / min to prepare Mixture B.

[0060] S13 Preparation of reaction solution: Slowly add mixture B to mixture A, ultrasonically disperse at 800 W power, and mechanically stir at 500 rpm / min for 30 hours to form a uniform reaction solution.

[0061] S2 Introduction of MoS2: 20 mg of MoS2 nanosheets were added to the above homogeneous reaction solution, ultrasonically dispersed at 800 W power, and mechanically stirred at 500 rpm / min for 4 hours to obtain a mixed reaction solution; then, the mixed reaction solution was transferred to a reaction vessel and subjected to liquid phase reaction at 120 °C for 18 hours.

[0062] S3 Aging and Post-treatment: After the reaction was completed, the mixture was aged overnight. The aged precipitate was then vacuum filtered, washed three times each with deionized water and ethanol, and dried in an oven at 60°C to obtain the final nitrogen-doped nickel cobalt hydroxide / MoS2 composite material.

[0063] Example 4 S11 Preparation of Mixture A: Weigh 100 mg of cobalt acetate and 200 mg of nickel acetate, add them to 80 g of N,N-dimethylformamide, ultrasonically disperse at 600 W power for 5 hours, and mechanically stir at 600 rpm / min to ensure that the raw materials are completely dissolved and uniformly dispersed to form Mixture A.

[0064] S12 Preparation of Mixture B: Weigh 15 mg of cetyltrimethylammonium bromide and mix with 120 g of deionized water, ultrasonically disperse at 600 W power for 5 hours, and mechanically stir at 600 rpm / min to prepare Mixture B.

[0065] S13 Preparation of reaction solution: Slowly add mixture B to mixture A, ultrasonically disperse at 500 W power, and mechanically stir at 800 rpm / min for 10 hours to form a uniform reaction solution.

[0066] S2 Introduction of MoS2: 32 mg of MoS2 nanosheets were added to the above homogeneous reaction solution, ultrasonically dispersed at 500 W power, and mechanically stirred at 800 rpm / min for 5 hours to obtain a mixed reaction solution; then, the mixed reaction solution was transferred to a reaction vessel and subjected to liquid phase reaction at 240 °C for 6 hours.

[0067] S3 Aging and Post-treatment: After the reaction was completed, the mixture was aged overnight. The aged precipitate was then vacuum filtered, washed three times each with deionized water and ethanol, and dried in an oven at 60°C to obtain the final nitrogen-doped nickel cobalt hydroxide / MoS2 composite material.

[0068] Comparative Example 1 S11 Preparation of Mixture A: Weigh 100 mg of cobalt acetate and 50 mg of nickel acetate, add them to 50 g of N,N-dimethylformamide, ultrasonically disperse at 1000 W power for 24 hours, and mechanically stir at 1000 rpm / min to ensure that the raw materials are completely dissolved and uniformly dispersed to form Mixture A.

[0069] S2 Introduction of MoS2: 16 mg of MoS2 nanosheets were added to the above mixture A, ultrasonically dispersed at 800 W power, and mechanically stirred at 600 rpm / min for 3 hours to obtain a mixed reaction solution; then, the mixed reaction solution was transferred to a reaction vessel and subjected to liquid phase reaction at 200℃ for 24 hours.

[0070] S3 Aging and Post-treatment: After the reaction was completed, the mixture was aged overnight. The aged precipitate was then vacuum filtered, washed three times each with deionized water and ethanol, and dried in an oven at 60°C to obtain the final nickel cobalt hydroxide / MoS2 composite material.

[0071] Comparative Example 2 S11 Preparation of Mixture A: Weigh 100 mg of cobalt acetate and 50 mg of nickel acetate, add them to 50 g of N,N-dimethylformamide, and ultrasonically disperse at 1000 W for 24 hours. Then, mechanically stir at 1000 rpm / min to ensure complete dissolution and uniform dispersion of the raw materials, forming Mixture A. Transfer Mixture A to a reaction vessel and carry out a liquid-phase reaction at 200℃ for 24 hours.

[0072] S3 Aging and Post-treatment: After the reaction is completed, the product is aged by standing overnight; then the aged precipitate is vacuum filtered, washed three times each with deionized water and ethanol, and dried in an oven at 60°C to obtain the final nickel-cobalt hydroxide.

[0073] Experimental example: Experiment Example 1: SEM Image Representation Using the material obtained in Example 1 as a sample, the morphology of the prepared nanomaterials was characterized using a Zeiss Sigma 300 SEM, and the results are as follows. Figure 1 As shown in the figure, the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared according to the method of the present invention has a plate-like stacked structure and a large electrochemically active specific surface area, which is beneficial to promoting the occurrence of electrochemical reactions.

[0074] Experimental Example 2: Electrochemical Performance Testing The materials prepared in Examples 1-4 above were subjected to electrochemical performance testing.

[0075] The method for testing electrochemical performance is as follows: The electrode materials prepared in Examples 1-4 were mixed with PTFE and conductive agent (acetylene black) in a ratio of 8:1:1 and uniformly coated onto nickel foam. After vacuum drying, they were used as electrodes, with a platinum sheet as the counter electrode and Hg / HgO as the reference electrode. A 3 M KOH solution was used as the electrolyte. Charge-discharge tests were conducted at different current densities, and the results are shown in Table 1.

[0076] Table 1: Discharge specific capacity of Examples 1-4 and Comparative Examples 1-2 at different current densities

[0077] As can be seen from Table 1, compared with Comparative Examples 1-2, the specific capacity of Examples 1-4 according to the present invention is significantly improved at various current densities. Among them, the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared in Example 1 has the highest specific capacity, reaching a maximum of 856.2 F / g at a current density of 0.5 A / g. This indicates that due to the addition of surfactant and MoS2, the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared according to the method of the present invention has better electrochemical performance.

[0078] Meanwhile, other electrical performance tests were conducted using the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared in Example 1 above as a sample.

[0079] Figure 2 The results of charge-discharge tests of the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared in Example 1 above are shown in the range of 0.5-10 A / g current densities. As can be seen from the figure, the charge-discharge curves of the material prepared according to the method of the present invention maintain a basically consistent shape at different current densities, indicating that the material possesses good rate performance.

[0080] Figure 3Cyclic voltammetry curves of the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material prepared in Example 1 above at different scan rates are shown. As can be seen from the figure, the material prepared according to the method of the present invention exhibits significant electrochemical bulging near 0.3 V and 0.5 V, indicating that the material has a relatively sensitive electrochemical response.

[0081] Figure 4 The AC impedance test of the material prepared in Example 1 above is shown in the frequency range of 0.01 Hz-100 kHz. As can be seen from the figure, the material prepared according to the method of the present invention has low internal resistance and interface resistance.

[0082] Based on the above electrical performance test results, it can be seen that the material prepared by the method according to the present invention exhibits excellent electrochemical performance due to the doping of a small amount of nitrogen element and its composite with molybdenum disulfide nanosheets, and is suitable as a supercapacitor electrode.

[0083] The above embodiments illustrate different parameter combinations for the synthesis method of nitrogen-doped nickel-cobalt hydroxide / MoS2 composite materials based on surfactant assistance. They are only used to illustrate specific implementations of the present invention and do not limit the scope of protection of the present invention.

Claims

1. A method for preparing a nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material, characterized in that, Includes the following steps: S1: A reaction solution is obtained by mixing cobalt salt, nickel salt, hexadecyltrimethylammonium bromide, organic solvent and deionized water; S2: MoS2 nanosheets are added to the reaction solution under ultrasonic dispersion and mechanical stirring to form mixture C; mixture C is transferred to a reaction vessel for reaction. S3: After the reaction is complete, allow it to stand and age; then vacuum filter, wash and dry the aged precipitate to obtain the final nitrogen-doped nickel cobalt hydroxide / MoS2 composite material.

2. The preparation method according to claim 1, characterized in that, In step S1, the cobalt salt is cobalt acetate, the nickel salt is nickel acetate, and the mass ratio of cobalt acetate to nickel acetate is 1:0.5-2.

3. The preparation method according to claim 2, characterized in that, In step S1, the organic solvent is N,N-dimethylformamide, and the mass ratio of cobalt acetate to N,N-dimethylformamide is 1:500-800.

4. The preparation method according to claim 3, characterized in that, In step S1, the mass ratio of hexadecyltrimethylammonium bromide to deionized water is 1:5000-10000, and the mass ratio of cobalt acetate to hexadecyltrimethylammonium bromide is 10:1-3.

5. The preparation method according to claim 1, characterized in that, In step S2, the mass ratio of cobalt acetate to MoS2 nanosheets is 10:1.6-3.2, the ultrasonic dispersion power is 500-800 W, the mechanical stirring speed is 300-800 rpm / min, and the stirring time is 2-5 hours.

6. The preparation method according to claim 1, characterized in that, In step S2, the reaction temperature is 120-240℃ and the reaction time is 6-24 hours.

7. The preparation method according to claim 4, characterized in that, Step S1 includes: S11 Preparation of Mixture A: Cobalt acetate and nickel acetate are weighed into N,N-dimethylformamide to form mixture A; S12 Preparation of Mixture B: Mix hexadecyltrimethylammonium bromide with deionized water to form mixture B; S13 Preparation of reaction solution: Mixture B and mixture A are mixed under ultrasonic dispersion and mechanical stirring to form a reaction solution; In step S13, the ultrasonic dispersion power is 500-800 W, the mechanical stirring speed is 300-800 rpm / min, and the stirring time is 10-30 hours.

8. The preparation method according to claim 7, characterized in that, Steps S11 and S12 include ultrasonic dispersion and mechanical stirring. In step S11, the ultrasonic dispersion power is 500-1000 W, the mechanical stirring speed is 400-1000 rpm / min, and the processing time is 5-24 hours. In step S12, the ultrasonic dispersion power is 500-1000 W, the mechanical stirring speed is 400-1000 rpm / min, and the stirring time is 5-24 hours.

9. A nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material, characterized in that, The composite material is prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the nitrogen-doped nickel-cobalt hydroxide / MoS2 composite material according to claim 9 in the preparation of supercapacitor electrodes.

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