A method for preparing a phosphorus-doped nickel-manganese bimetallic sulfide composite material and its application in supercapacitors.

Abstract

This invention discloses a method for preparing a phosphorus-doped nickel-manganese bimetallic sulfide composite material and its application in supercapacitors. The method uses readily available and relatively inexpensive raw materials, resulting in low cost. The preparation process is simple and has a short cycle time, making it suitable for mass production and commercial applications. Supercapacitors made using the phosphorus-doped nickel-manganese bimetallic sulfide composite material prepared in this invention as the positive electrode material and conductive carbon black as the negative electrode can significantly improve their specific capacity and energy density efficiency; meeting the battery market's demand for high-specific-capacity batteries; and possessing high practical application value.

Description

Technical Field

[0001] This invention belongs to the field of supercapacitors, and particularly relates to a phosphorus-doped nickel-manganese bimetallic sulfide composite material and its preparation method, belonging to the field of supercapacitor cathodes. Background Technology

[0002] In electrochemical energy storage devices, supercapacitors, due to their excellent overall performance, are strong competitors to high-performance energy storage systems and have been widely used in many fields. Compared with lithium-ion batteries, the most prominent features of supercapacitors are their superior power density and rapid charge / discharge capabilities. Furthermore, supercapacitors also offer advantages such as long lifespan, low cost, and environmental friendliness. However, supercapacitors are still far from being practically applicable for high-energy storage in real-world scenarios because their energy density (carbon-based symmetric supercapacitors ~5 Wh / kg) is limited. -1 Asymmetric supercapacitors <100 Wh / kg -1 ) and other energy storage devices such as lithium-ion batteries (170~250 Wh kg) -1 ) and fuel cells (~350 Wh kg) -1 Compared to other products, it is not significantly competitive.

[0003] Maintaining the high power and cycle stability of supercapacitors while simultaneously increasing their energy density to approach the comprehensive application capabilities of lithium-ion batteries in various fields is currently a hot research topic in the lithium-ion battery field both domestically and internationally. Developing high-performance electrode materials is a key approach to overcoming the energy density limitations of supercapacitors. Traditional carbon-based electrode materials (such as activated carbon and graphene) primarily rely on the double-layer mechanism for energy storage. While they possess high conductivity and excellent cycle stability, their specific capacitance is typically low (~300 F g). -1 However, this makes it difficult to meet the demands for high energy density. Transition metal-based materials (such as oxides, sulfides, and phosphides) based on surface redox reactions can achieve higher specific capacitance through pseudocapacitance or battery-type energy storage mechanisms. Among transition metal compounds, metal sulfides are more advantageous than metal oxides due to their unique physicochemical properties. Sulfur has a lower electronegativity than oxygen, resulting in stronger covalent bonds in the metal-sulfur bond and a narrower band gap, thus exhibiting higher intrinsic conductivity. Simultaneously, the larger radius of sulfur atoms and the looser layered structure facilitate rapid insertion / extraction of electrolyte ions, providing more abundant redox active sites.

[0004] To further optimize the electrochemical performance of metal sulfides, elemental doping strategies are widely adopted. Introducing heteroatoms (such as phosphorus, nitrogen, and oxygen) can effectively modulate the electronic structure, surface properties, and crystal structure of materials, thereby increasing the number of active sites, improving conductivity, and enhancing structural stability. Phosphorus, as a common dopant element, exhibits a significantly different electronegativity from metal atoms, inducing charge redistribution and optimizing the electronic structure and reactivity of the material. The covalent radius of phosphorus atoms also differs from that of sulfur atoms, causing lattice distortion after doping and exposing more highly active crystal planes. Simultaneously, phosphorus's 3p orbitals can couple with the d orbitals of metals, altering the charge density distribution of the material and promoting charge transfer kinetics.

[0005] Therefore, it is essential to explore efficient, environmentally friendly, and high-raw-material-utilization methods for preparing phosphorus-doped nickel-manganese bimetallic sulfide composite materials. Summary of the Invention

[0006] The purpose of this invention is to address the problems of high energy consumption, low efficiency, toxicity, and environmental pollution in the preparation of phosphorus-doped nickel-manganese bimetallic sulfide composite materials, and to provide a method for preparing phosphorus-doped sulfide composite materials with high utilization and no toxicity or harm.

[0007] To achieve the above objectives, the present invention adopts the following technical solution to prepare phosphorus-doped nickel-manganese bimetallic sulfide composite materials.

[0008] (A1) Weigh out a nickel-manganese metal salt compound in a certain proportion and dissolve it in a solvent at a certain temperature;

[0009] (A2) Dissolve thiourea in deionized water;

[0010] (A3) Dissolve the surfactant in deionized water;

[0011] (A4) Dissolve a certain amount of phosphorus source in deionized water;

[0012] (A5) Add solutions A2, A3 and A4 into solution A1 in sequence and stir thoroughly to obtain a transparent solution.

[0013] (A6) Transfer the A5 solution to a polytetrafluoroethylene hydrothermal reactor for hydrothermal reaction.

[0014] In the above implementation, the nickel-manganese bimetallic salt compound is two of the following nickel-manganese bimetallic salt compounds: nickel acetate, manganese acetate, nickel sulfate, and manganese sulfate. In the preferred implementation, the nickel-manganese bimetallic compound is nickel acetate or manganese acetate.

[0015] In the above implementations, the ratio of nickel-manganese bimetallic compounds is 1:10 to 10:1, and in the preferred implementation, the ratio of nickel-based metal salt compounds to manganese-based metal salt compounds is 4:1.

[0016] In the above implementation, the amount of thiourea used is 0 to 100% of the mass of nickel-manganese bimetallic compound nickel-manganese, and preferably, the amount of thiourea used is 50% of the mass of nickel-manganese bimetallic compound nickel-manganese.

[0017] In the above implementation methods, the types of surfactants include hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, sodium dodecyl sulfonate, etc., and the preferred type of surfactant in the implementation method is hexadecyltrimethylammonium bromide.

[0018] In the above implementation, the amount of surfactant used is 0-20% of the mass of thiourea, and the preferred implementation is 10% of the mass of thiourea.

[0019] In the above implementation methods, the types of phosphorus sources include sodium phosphate, sodium phosphite, sodium hydrogen phosphate, sodium dihydrogen phosphate, etc., and sodium dihydrogen phosphate is the preferred phosphorus source in the implementation method.

[0020] In the above implementation methods, the amount of phosphorus source used is 0 to 10% of the mass of nickel-manganese bimetallic compound nickel-manganese, and in the preferred phosphorus implementation method, the amount of phosphorus source used is 1% of the mass of manganese bimetallic compound nickel-manganese.

[0021] In the above implementation methods, the stirring time is 5-30 minutes, with 10 minutes being the preferred method.

[0022] In the above implementation methods, the temperature of the hydrothermal reaction is 160-200℃, and the preferred implementation method is 180℃.

[0023] In the above implementation methods, the hydrothermal time is 2-24 hours, with the preferred implementation method being 6 hours.

[0024] Another objective of this invention is to provide an application of the above-mentioned composite material in the preparation of supercapacitors. The supercapacitor prepared based on this positive electrode can significantly improve the specific capacitance and energy density of the supercapacitor, and has high practical application value.

[0025] To achieve the above objectives, the present invention adopts the following technical solution to experimentally prepare the positive electrode material of supercapacitors.

[0026] (B1) The composite material, conductive agent, and PVDF are added to the mortar in a certain mass ratio and ground thoroughly;

[0027] (B2) The mixed slurry obtained in B1 is coated onto the current collector to obtain the precursor material of the cathode material;

[0028] (B3) Transfer the cathode material precursor obtained in B2 to an oven for drying;

[0029] (B4) The material obtained in B3 is compacted under a tablet press to obtain the positive electrode material of a supercapacitor.

[0030] In the above implementation methods, the types of conductive agents include acetylene black, Ketjen black, and carbon nanotubes, with acetylene black being the preferred implementation method;

[0031] In the above implementation methods, the ratio of composite material, conductive agent, and PVDF is 1~10:1:1, with a preferred ratio of 8:1:1.

[0032] In the above implementation methods, the current collector can be made of materials such as nickel foam, aluminum foil, carbon-coated aluminum foil, and carbon paper, with nickel foam being the preferred implementation method.

[0033] In the above implementation methods, the temperature of the drying oven is 50~80℃, with 70℃ being the preferred implementation method; the drying time is 0.5~10 hours, with 6 hours being the preferred implementation method.

[0034] In the above implementation methods, the pressure of the tablet press is 3~10 MPa, and the preferred implementation method is 7 MPa.

[0035] The preparation method for the negative electrode of all supercapacitor button devices in the above implementation is as follows: conductive carbon black, acetylene black, and PTFE are mixed in a mass ratio of 8:1:1, a few drops of anhydrous ethanol are added, and the mixture is thoroughly ground in a mortar. The mud-like mixture is then coated onto a nickel foam current collector, placed in a 70 ℃ oven for 6 h, and then pressed using a tablet press at a pressure of 7 MPa to obtain a thin negative electrode sheet.

[0036] The fabrication method for all supercapacitor button cells in the above implementation is as follows: the button cell supercapacitor is assembled in the order of positive electrode shell, positive electrode, separator, negative electrode, gasket, spring, and negative electrode shell. Both the positive and negative electrodes are monolithic electrodes, the electrolyte is 2 M KOH, and the separator is a cellulose membrane.

[0037] The technical effects and advantages of this invention are as follows:

[0038] 1. This invention provides a novel method for preparing phosphorus-doped nickel-manganese bimetallic sulfide composite materials. This method uses readily available and relatively inexpensive raw materials, resulting in low cost. The preparation process is simple and has a short cycle time, making it suitable for mass production and commercial applications.

[0039] 2. The supercapacitor made using the phosphorus-doped nickel-manganese bimetallic sulfide composite material prepared in this invention as the positive electrode material and conductive carbon black as the negative electrode can significantly improve its specific capacity and energy density efficiency; it meets the battery market's demand for high specific capacity batteries; and it has high practical application value. Attached Figure Description

[0040] Appendix Figure 1XRD patterns of composite materials with different phosphorus doping levels.

[0041] Appendix Figure 2 Infrared images of composite materials with different phosphorus doping levels.

[0042] Appendix Figure 3 Raman spectroscopy of composite materials with different phosphorus doping levels.

[0043] Appendix Figure 4 SEM / TEM and TEM mapping images of phosphorus-doped nickel-manganese bimetallic sulfide composite materials.

[0044] Appendix Figure 5 The supercapacitor prepared by phosphorus-doped nickel-manganese bimetallic sulfide composite material is shown in the EIS image.

[0045] Appendix Figure 6 Supercapacitors prepared from different phosphorus-doped nickel-manganese bimetallic sulfide composite materials at 1 A g -1 GCD curves at current density.

[0046] Appendix Figure 7 GCD curves of supercapacitors prepared from phosphorus-doped nickel-manganese bimetallic sulfide composites at different current densities.

[0047] Appendix Figure 8 Cyclic curves of supercapacitors prepared from phosphorus-doped nickel-manganese bimetallic sulfide composite materials. Detailed Implementation

[0048] The technical solutions of various embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are part of the present invention.

[0049] The following detailed description, in conjunction with the accompanying drawings and examples, further illustrates the preparation method of the nano-sulfur particles of the present invention and their application in lithium-sulfur batteries. The illustrative embodiments and descriptions of the present invention are for explaining the invention and do not constitute any limitation thereof.

[0050] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0051] In the following examples, all raw materials were purchased from Chengdu Kelong Reagent Co., Ltd.

[0052] Example 1:

[0053] The method for preparing the phosphorus-doped nickel-manganese bimetallic sulfide composite supercapacitor cathode material provided in this embodiment includes the following steps:

[0054] (1) Weigh out 0.9g of nickel acetate and 0.225g of manganese acetate respectively, dissolve them in 35 mL of deionized water, stir thoroughly to dissolve, and obtain solution 1;

[0055] (2) Weigh 0.56g of thiourea and add it to 35 mL of deionized water. Stir thoroughly to dissolve and obtain solution 2.

[0056] (3) Add 0.056g of cetyltrimethylammonium bromide to 50 mL of deionized water and stir thoroughly to dissolve, to obtain solution 3;

[0057] (4) Dissolve 0.011 g of sodium dihydrogen phosphate in 20 mL of deionized water and stir thoroughly to obtain solution 4;

[0058] (5) Slowly add solutions 2, 3, and 4 into solution 1 to obtain solution 5;

[0059] (6) Transfer solution 5 to a polytetrafluoroethylene reactor and hydrothermally react at 180 °C for 6 h. After the reaction is complete, take out the sample, wash it several times with deionized water and anhydrous ethanol, and then dry it to obtain product 1.

[0060] (7) Mix product 1 powder with acetylene black and PVDF in a mass ratio of 8:1:1, add a few drops of NMP, grind in a mortar to form a mixed slurry, and coat it onto the nickel foam current collector. After placing in a 70 ℃ oven for 6 h, take it out and press it with a tablet press at a pressure of 7 MPa to obtain a positive electrode sheet.

[0061] Example 2:

[0062] The method for preparing the phosphorus-doped nickel-manganese bimetallic sulfide composite supercapacitor cathode material provided in this embodiment includes the following steps:

[0063] (1) Weigh 0.225g of nickel acetate and 0.9g of manganese acetate respectively and dissolve them in 35 mL of deionized water. Stir thoroughly to dissolve and obtain solution 1;

[0064] (2) Weigh 0.5g of thiourea and add it to 35 mL of deionized water. Stir thoroughly to dissolve and obtain solution 2.

[0065] (3) Add 0.1g of dodecyltrimethylammonium bromide to 50 mL of deionized water and stir thoroughly to dissolve, to obtain solution 3;

[0066] (4) Dissolve 0.02 g of sodium phosphate in 20 mL of deionized water and stir thoroughly to obtain solution 4;

[0067] (5) Slowly add solutions 2, 3, and 4 into solution 1 to obtain solution 5;

[0068] (6) Transfer solution 5 to a polytetrafluoroethylene reactor and hydrothermally react at 180 °C for 6 h. After the reaction is complete, take out the sample, wash it several times with deionized water and anhydrous ethanol, and then dry it to obtain product 1.

[0069] (7) Mix product 1 powder with acetylene black and PVDF in a mass ratio of 8:2:1, add a few drops of NMP, grind in a mortar to form a mixed slurry, and coat it onto the nickel foam current collector. After placing in a 70 ℃ oven for 4 h, take it out and press it with a tablet press at a pressure of 5 MPa to obtain a positive electrode sheet.

[0070] Example 3:

[0071] The method for preparing the phosphorus-doped nickel-manganese bimetallic sulfide composite supercapacitor cathode material provided in this embodiment includes the following steps:

[0072] (1) Weigh out 0.5g of nickel sulfate and 0.5g of manganese sulfate respectively, dissolve them in 35 mL of deionized water, stir thoroughly to dissolve, and obtain solution 1;

[0073] (2) Weigh 1g of thiourea and add it to 35 mL of deionized water. Stir thoroughly to dissolve and obtain solution 2.

[0074] (3) Add 0.1g sodium dodecyl sulfonate to 50 mL of deionized water and stir thoroughly to dissolve, to obtain solution 3;

[0075] (4) Dissolve 0.02 g of sodium phosphite in 20 mL of deionized water and stir thoroughly to obtain solution 4;

[0076] (5) Slowly add solutions 2, 3, and 4 into solution 1 to obtain solution 5;

[0077] (6) Transfer solution 5 to a polytetrafluoroethylene reactor and hydrothermally react at 150 °C for 6 h. After the reaction is complete, take out the sample, wash it several times with deionized water and anhydrous ethanol, and then dry it to obtain product 1.

[0078] (7) Mix product 1 powder with Ketjen black and PVDF in a mass ratio of 4:1:1, add a few drops of NMP, grind in a mortar to form a mixed slurry, and coat it onto the nickel foam current collector. After placing in a 70 ℃ oven for 4 h, take it out and press it with a tablet press at a pressure of 5 MPa to obtain a positive electrode sheet.

[0079] Example 4:

[0080] The method for preparing the phosphorus-doped nickel-manganese bimetallic sulfide composite supercapacitor cathode material provided in this embodiment includes the following steps:

[0081] (1) Weigh out 0.5g of nickel sulfate and 0.5g of manganese sulfate respectively, dissolve them in 35 mL of deionized water, stir thoroughly to dissolve, and obtain solution 1;

[0082] (2) Weigh 1g of thiourea and add it to 35 mL of deionized water. Stir thoroughly to dissolve and obtain solution 2.

[0083] (3) Add 0.1g sodium dodecyl sulfonate to 50 mL of deionized water and stir thoroughly to dissolve, to obtain solution 3;

[0084] (4) Dissolve 0.02 g of sodium phosphite in 20 mL of deionized water and stir thoroughly to obtain solution 4;

[0085] (5) Slowly add solutions 2, 3, and 4 into solution 1 to obtain solution 5;

[0086] (6) Transfer solution 5 to a polytetrafluoroethylene reactor and hydrothermally react at 150 °C for 6 h. After the reaction is complete, take out the sample, wash it several times with deionized water and anhydrous ethanol, and then dry it to obtain product 1.

[0087] (7) Mix product 1 powder with Ketjen black and PVDF in a mass ratio of 4:1:1, add a few drops of NMP, grind in a mortar to form a mixed slurry, and coat it onto the nickel foam current collector. After placing in a 70 ℃ oven for 4 h, take it out and press it with a tablet press at a pressure of 5 MPa to obtain a positive electrode sheet.

[0088] Example 5:

[0089] The method for preparing the phosphorus-doped nickel-manganese bimetallic sulfide composite supercapacitor cathode material provided in this embodiment includes the following steps:

[0090] (1) Weigh 0.15g of nickel sulfate and 0.25g of manganese sulfate respectively and dissolve them in 35 mL of deionized water. Stir thoroughly to dissolve and obtain solution 1;

[0091] (2) Weigh 0.5g of thiourea and add it to 35 mL of deionized water. Stir thoroughly to dissolve and obtain solution 2.

[0092] (3) Add 0.1 g of hexadecyltrimethylammonium bromide to 50 mL of deionized water and stir thoroughly to dissolve, to obtain solution 3;

[0093] (4) Dissolve 0.02 g of sodium phosphite in 20 mL of deionized water and stir thoroughly to obtain solution 4;

[0094] (5) Slowly add solutions 2, 3, and 4 into solution 1 to obtain solution 5;

[0095] (6) Transfer solution 5 to a polytetrafluoroethylene reactor and hydrothermally react at 150 °C for 6 h. After the reaction is complete, take out the sample, wash it several times with deionized water and anhydrous ethanol, and then dry it to obtain product 1.

[0096] (7) Mix product 1 powder with Ketjen black and PVDF in a mass ratio of 8:3:1, add a few drops of NMP, grind in a mortar to form a mixed slurry, and coat it onto the nickel foam current collector. After placing in a 70 ℃ oven for 4 h, take it out and press it with a tablet press at a pressure of 5 MPa to obtain a positive electrode sheet.

[0097] Examples 1 to 5

[0098] Preparation of negative electrode material: Conductive carbon black, acetylene black, and PTFE were mixed in a mass ratio of 8:1:1, and a few drops of anhydrous ethanol were added. The mixture was then thoroughly ground in a mortar. The mud-like mixture was then coated onto a nickel foam current collector, placed in an oven at 70 °C for 6 h, and then pressed using a tablet press at a pressure of 7 MPa to obtain a thin negative electrode sheet.

[0099] Assembly of the coin cell: The coin cell supercapacitor was assembled in the following order: positive electrode shell, positive electrode, separator, negative electrode, gasket, spring, and negative electrode shell. Both the positive and negative electrodes are monolithic electrodes, the electrolyte is 2 M KOH, and the separator is a cellulose membrane.

[0100] Comparative example:

[0101] (1) Weigh out 0.9g of nickel acetate and 0.225g of manganese acetate respectively, dissolve them in 35 mL of deionized water, stir thoroughly to dissolve, and obtain solution 1;

[0102] (2) Weigh 0.56g of thiourea and add it to 35 mL of deionized water. Stir thoroughly to dissolve and obtain solution 2.

[0103] (3) Add 0.056g of cetyltrimethylammonium bromide to 50 mL of deionized water and stir thoroughly to dissolve, to obtain solution 3;

[0104] (4) Slowly add solutions 2 and 3 into solution 1 to obtain solution 5;

[0105] (5) Transfer solution 5 to a polytetrafluoroethylene reactor and hydrothermally react at 180 °C for 6 h. After the reaction is complete, take out the sample, wash it several times with deionized water and anhydrous ethanol, and then dry it to obtain product 1.

[0106] (6) Mix product 1 powder with acetylene black and PVDF in a mass ratio of 8:1:1, add a few drops of NMP, grind in a mortar to form a mixed slurry, and coat it onto the nickel foam current collector. After placing in a 70 ℃ oven for 6 h, take it out and press it with a tablet press at a pressure of 7 MPa to obtain a positive electrode sheet.

[0107] Preparation of negative electrode material: Conductive carbon black, acetylene black, and PTFE were mixed in a mass ratio of 8:1:1, and a few drops of anhydrous ethanol were added. The mixture was then thoroughly ground in a mortar. The mud-like mixture was then coated onto a nickel foam current collector, placed in an oven at 70 °C for 6 h, and then pressed using a tablet press at a pressure of 7 MPa to obtain a thin negative electrode sheet.

[0108] Assembly of the coin cell: The coin cell supercapacitor was assembled in the following order: positive electrode shell, positive electrode, separator, negative electrode, gasket, spring, and negative electrode shell. Both the positive and negative electrodes are monolithic electrodes, the electrolyte is 2 M KOH, and the separator is a cellulose membrane.

[0109] Supercapacitor coin cell performance analysis:

[0110] Table 1. Test results of supercapacitor button cells

[0111] <![CDATA[Current density (A g -1 )]]> <![CDATA[Specific capacitance (F g -1 )]]> <![CDATA[Current density (A g -1 ).]]> <![CDATA[Specific capacitance (F g -1 )]]> <![CDATA[Current density (A g -1 ).]]> <![CDATA[Specific capacitance (F g -1 )]]> <![CDATA[Current density (A g -1 ).]]> <![CDATA[Specific capacitance (F g -1 )]]> Example 1 1 1675.4 2 798.7 5 324.5 10 127.5 Example 2 1 1328.3 2 689.7 5 257.8 10 98.7 Example 3 1 1172.5 3 627.5 5 234.7 10 88.7 Example 4 1 1087.3 802 602.6 5 232.1 10 78.6 Example 5 1 995.7 897.4 598.5 5 217.5 10 66.5 Comparative Example 1 973.2 865.3 542.7 5 198.6 10 57.2

[0112] The button cells prepared in Examples 1-5 and the comparative examples were tested on the Shanghai Chenhua Electrochemical Workstation.

[0113] The test data above show that the button cell assembled from the supercapacitor cathode material prepared by the method of this invention has high electrochemical performance, especially compared with the comparative example, both the specific capacity and conductivity are further improved.

[0114] In summary, the supercapacitor cathode material provided by this invention comprises three parts: a phosphorus-doped nickel-manganese bimetallic sulfide composite material, a conductive agent, and a current collector. Among them, the phosphorus-doped nickel-manganese bimetallic sulfide composite material can effectively regulate the electronic structure, surface properties, and crystal structure of the material, thereby increasing the number of active sites, improving conductivity, and enhancing structural stability.

[0115] Furthermore, the button supercapacitor made from the supercapacitor positive electrode material provided by this invention has a simple manufacturing process, short cycle time, low cost, excellent performance, and high specific capacitance and cycle life, and has great potential for market application.

[0116] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for preparing a phosphorus-doped nickel-manganese bimetallic sulfide composite material, characterized in that, Includes the following steps: (A1) Weigh out nickel salt and manganese salt in a certain proportion and dissolve them in a solvent at a certain temperature to obtain solution A1; (A2) Dissolve thiourea in deionized water to obtain solution A2; (A3) Dissolve surfactant in deionized water to obtain solution A3; (A4) Dissolve phosphorus source in deionized water to obtain solution A4, wherein the amount of phosphorus source is 1-10% of the total mass of nickel salt and manganese salt; (A5) Add solutions A2, A3, and A4 dropwise to solution A1 in sequence and stir thoroughly to obtain a transparent solution; (A6) Transfer the solution obtained in step A5 to a polytetrafluoroethylene hydrothermal reactor and carry out a hydrothermal reaction at a temperature of 160-200℃ for 2-24 hours; (A7) Take out the sample after the hydrothermal reaction, wash it several times with deionized water and anhydrous ethanol, and then dry it.

2. The method for preparing a phosphorus-doped nickel-manganese bimetallic sulfide composite material according to claim 1, characterized in that: The nickel salt is nickel acetate or nickel sulfate, and the manganese salt is manganese acetate or manganese sulfate; the ratio of nickel salt to manganese salt is 1:10 to 10:

1.

3. The method for preparing a phosphorus-doped nickel-manganese bimetallic sulfide composite material according to claim 1, characterized in that: The types of surfactants include hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and sodium dodecyl sulfonate; the amount of surfactant used is 0-20% of the mass of thiourea.

4. The method for preparing a phosphorus-doped nickel-manganese bimetallic sulfide composite material according to claim 1, characterized in that: Phosphorus sources include sodium phosphate, sodium phosphite, sodium hydrogen phosphate, and sodium dihydrogen phosphate.

5. The method for preparing a phosphorus-doped nickel-manganese bimetallic sulfide composite material according to claim 1, characterized in that: Stirring time is 5-30 minutes.

6. The application of the phosphorus-doped nickel-manganese bimetallic sulfide composite material according to any one of claims 1-5, characterized in that: The above-mentioned composite material is used in the preparation of the positive electrode of supercapacitor.

7. The application of the phosphorus-doped nickel-manganese bimetallic sulfide composite material according to claim 6, characterized in that, The following technical solution was adopted to prepare the positive electrode material of the supercapacitor: (B1) The composite material, conductive agent and PVDF were added into the mortar according to a certain mass ratio and ground thoroughly; (B2) The mixed slurry obtained in B1 was coated onto the current collector to obtain the precursor material of the positive electrode material. (B3) Transfer the cathode material precursor obtained in B2 to an oven for drying; (B4) The material obtained in B3 is compacted under a tablet press to obtain the positive electrode material of a supercapacitor.

8. The application of the phosphorus-doped nickel-manganese bimetallic sulfide composite material according to claim 6, characterized in that, The mass ratio of composite material, conductive agent, and PVDF is 1~10:1:

1.

9. The application of the phosphorus-doped nickel-manganese bimetallic sulfide composite material according to claim 6, characterized in that, The oven temperature is 50~80℃; the drying time is 0.5~10 hours; the pressure of the tablet press is 3~10 MPa.

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