Carbon nanosphere-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material and preparation method and application thereof

Abstract

The invention relates to the technical field of electrode material preparation, in particular to a carbon nanosphere-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material and a preparation method and application thereof, nanoneedle-shaped manganese-doped nickel-cobalt sulfide grows on the surface of carbon cloth in situ, and the surface of each nanoneedle is coated with a carbon sphere layer. The preparation method comprises the following steps: firstly, growing a manganese-doped nickel-cobalt precursor with controllable morphology on carbon cloth in situ, coating the surface of the nickel-cobalt precursor with polydopamine in situ at room temperature by virtue of electrostatic interaction between negative ions and negative charges in the precursor and amido positive charges in dopamine hydrochloride, and then vulcanizing and carbonizing to obtain a target product. The coated carbon sphere layer is beneficial to accelerating the electron conduction rate of the nickel-cobalt sulfide, providing abundant reaction active sites, accelerating the kinetics of ion transmission in the oxidation-reduction reaction process, improving the structural stability of the electrode material, inhibiting the volume expansion of the active substance in the circulation process, and improving the specific capacitance, the rate and the circulation stability of the electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state supercapacitor electrode material preparation, and specifically relates to a nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material, and a preparation method and application thereof. Background Art

[0002] Supercapacitors have shown broad application prospects in various portable electronic devices, electric vehicles, wearable devices, medical devices and military fields due to their advantages such as high power density, long cycle durability and fast charge and discharge capabilities. Compared with traditional liquid electrolyte supercapacitors, solid-state supercapacitors usually use gel electrolytes, which will not cause failures such as electrolyte leakage, and can be integrated on a single chip in various shapes. They are fast energy storage devices for future smart wearable electronics. The electrode material has a crucial impact on the performance of supercapacitors. Carbon cloth and carbon fiber-based flexible supercapacitor electrode materials are expected to be used in clothing weaving and integration due to their light weight, small size and strong deformation resistance.

[0003] Transition metal nickel-cobalt compounds have cobalt and nickel extranuclear electrons. d The presence of vacancies in the orbital and the abundance of valence electrons can improve the charge storage capacity through multi-electron transfer via Faraday redox reactions. It is a potential pseudocapacitive electrode material, but its application as an electrode material in supercapacitors is still limited by the following defects: (1) due to repeated volume expansion / contraction, the structural stability is poor during long-term charge / discharge cycles; (2) low rate capability, especially affected by low intrinsic conductivity, faces the problem of slow redox reaction kinetics during charge and discharge; (3) poor electronic / ionic conductivity and lack of redox activity lead to low energy density, which limits their application. To solve these problems, the introduction of nickel cobalt sulfide into carbon cloth substrate or the coating of carbon-based materials with high conductivity and high specific surface area on the surface of active materials can significantly increase the conductivity of electrode materials and buffer the volume change of electrodes during charge and discharge, thereby improving their specific capacity and cycle life. Therefore, it is very important to design flexible electrode materials with reasonable structure, enhanced interfacial charge transfer and excellent pseudocapacitive activity. Summary of the invention

[0004] The purpose of the present invention is to provide a nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material and its preparation method and application, so as to solve the defects of transition metal nickel-cobalt compounds such as poor structural stability, slow redox reaction kinetics, and low conductivity during long-term charge / discharge cycles; using carbon cloth as a substrate, a manganese-doped nickel-cobalt precursor is in situ grown and loaded on the carbon cloth substrate through a hydrothermal reaction, polydopamine is in situ coated on the surface of the manganese-doped nickel-cobalt precursor through an in situ self-polymerization reaction at room temperature, and then a carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material is obtained through a hydrothermal sulfidation and calcination process. The carbon ball layer is conducive to accelerating the electron conduction rate of nickel-cobalt sulfide, providing abundant reaction active sites, accelerating the kinetics of ion transmission during the redox reaction, inhibiting the volume expansion of active substances during the cycle, improving the structural stability of the electrode material, and improving the electrode specific capacitance, rate and cycle stability. By simply adjusting the time of coating polydopamine, the thickness of the nanocarbon ball layer can be controlled, and an electrode material with high specific capacitance, good rate performance and excellent cycle stability can be produced for use in hybrid solid-state flexible supercapacitors.

[0005] The primary purpose of the present invention is to propose a nano-carbon ball-coated manganese-doped nickel cobalt sulfide / carbon cloth flexible electrode material, in which manganese-doped nickel cobalt sulfide is in situ grown on the surface of the carbon cloth, the manganese-doped nickel cobalt sulfide is in the shape of a nano-needle, and the surface of each nano-needle is also coated with a carbon ball layer.

[0006] Furthermore, the diameter of the nanoneedles is 40~100 nm, and the particle size of the carbon spheres is 10~50 nm.

[0007] Another object of the present invention is to provide a method for preparing a nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material, which specifically comprises the following steps: (1) Pretreatment of carbon cloth CC; (2) Preparation of manganese-doped nickel-cobalt precursor / CC: dissolving hydrated nickel salt, hydrated cobalt salt and hydrated manganese salt in deionized water to obtain a metal ion mixture, adding urea and ammonium fluoride to the metal ion mixture, stirring until dissolved, and forming solution A; immersing the carbon cloth CC pretreated in step (1) in solution A and standing for 4 to 6 hours, then transferring it to a hydrothermal reactor for hydrothermal reaction, and naturally cooling to room temperature after the reaction, taking out the reacted carbon cloth, washing it with deionized water, and then drying it to obtain a nano-needle-shaped manganese-doped nickel-cobalt precursor grown in situ on the carbon cloth, which is recorded as manganese-doped nickel-cobalt precursor / CC; (3) Preparation of manganese-doped nickel-cobalt precursor @PDA / CC: Add tris(hydroxymethyl)aminomethane to an ethanol aqueous solution and stir to dissolve the mixture, adjust the pH value of the solution to 8.5, and then add dopamine hydrochloride to dissolve the mixture to obtain solution B; place the manganese-doped nickel-cobalt precursor / CC obtained in step (2) into solution B, and allow the mixture to react at room temperature for 24 to 96 h, replace solution B every 24 h, take out the carbon cloth after the reaction, wash it with deionized water, and then dry it to obtain a carbon cloth with polydopamine in situ coated on the surface of the manganese-doped nickel-cobalt precursor, which is recorded as manganese-doped nickel-cobalt precursor @PDA / CC; (4) Preparation of manganese-doped nickel-cobalt sulfide @PDA / CC: dissolving sodium sulfide nonahydrate in deionized water to form a solution C, immersing the manganese-doped nickel-cobalt precursor @PDA / CC obtained in step (3) in the solution C and transferring the whole of the solution into a hydrothermal reactor for a hydrothermal sulfidation reaction. After the reaction is completed, the mixture is naturally cooled to room temperature. The carbon cloth after the reaction is taken out, washed with deionized water, and then dried to obtain manganese-doped nickel-cobalt sulfide @PDA / CC; (5) Preparation of manganese-doped nickel cobalt sulfide@carbon ball / CC: The manganese-doped nickel cobalt sulfide@PDA / CC obtained in step (4) was calcined in an argon atmosphere at a calcination temperature of 500-600°C, a heating rate of 2°C / min, and a holding time of 60-180 min. After the calcination, it was naturally cooled to room temperature and taken out to obtain a nano-carbon ball-coated manganese-doped nickel cobalt sulfide / carbon cloth flexible electrode material, which was recorded as manganese-doped nickel cobalt sulfide@carbon ball / CC.

[0008] Furthermore, in step (1) of the above preparation method, the pretreatment process of the carbon cloth includes: ultrasonically washing the carbon cloth with anhydrous ethanol and acetone in sequence, placing it in a drying oven for drying, and then immersing it in concentrated sulfuric acid or concentrated nitric acid for 4 to 12 hours, taking out the soaked carbon cloth and washing it with deionized water for multiple times, placing it in a drying oven for drying, and finally placing it in a Ma Fuel furnace, heating it to 400 to 500°C, roasting it for 2 to 6 hours, and naturally cooling it to room temperature after roasting to obtain the pretreated carbon cloth.

[0009] Furthermore, in step (2) of the above preparation method, the hydrated nickel salt is selected from one of nickel nitrate hexahydrate and nickel chloride hexahydrate, the hydrated cobalt salt is selected from one of cobalt nitrate hexahydrate and cobalt chloride hexahydrate, and the hydrated manganese salt is selected from manganese chloride tetrahydrate; the temperature of the hydrothermal reaction is 120° C., and the reaction time is 8 h.

[0010] Furthermore, the molar ratio of hydrated nickel salt, hydrated cobalt salt, hydrated manganese salt, urea and ammonium fluoride is 1:2:0.5:4:2, the concentration of hydrated nickel salt in solution A is 0.01-0.03 mol / L, the concentration of hydrated cobalt salt is 0.02-0.06 mol / L, and the concentration of hydrated manganese salt is 0.005-0.015 mol / L.

[0011] Furthermore, in step (3) of the above preparation method, the concentration of tris(hydroxymethyl)aminomethane in solution B is 0.01 to 0.03 mol / L, the concentration of dopamine hydrochloride is 0.01 to 0.06 mol / L, and the ethanol aqueous solution is obtained by mixing anhydrous ethanol and water, and the volume ratio of anhydrous ethanol to water is 1:1 to 1:4.

[0012] Furthermore, in step (4) of the above preparation method, the concentration of sodium sulfide nonahydrate in solution C is 0.2-0.6 mol / L, the temperature of the hydrothermal sulfidation reaction is 160° C., and the reaction time is 6-8 h.

[0013] Another object of the present invention is to provide a nano-carbon ball-coated manganese-doped nickel cobalt sulfide / carbon cloth flexible electrode material obtained according to the above preparation method as an energy storage electrode material in a supercapacitor, and the nano-carbon ball-coated manganese-doped nickel cobalt sulfide / carbon cloth flexible electrode material can be directly used as a working electrode.

[0014] In the above application, nano-carbon sphere-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material was used as the working electrode, platinum sheet electrode was used as the counter electrode, Hg / HgO electrode was used as the reference electrode, and the electrolyte was 6 mol / L KOH at 1 mA / cm 2 When the area specific capacitance of the nano-carbon sphere-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material is 2900~4400 mF / cm 2 ; 30 mA / cm 2 When the area specific capacitance of the nano-carbon sphere-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material is 2200~3700mF / cm 2 The rate performance is 74~85%, and the area specific capacitance retention rate after 5000 cycles is 90~98%.

[0015] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the present invention can achieve considerable technical progress and practicality, and has a wide range of utilization value, and has at least the following advantages: (1) The present invention obtains hydrophilic carbon cloth by pre-treating commercial carbon cloth, and in-situ grows a manganese-doped nickel-cobalt precursor with controllable morphology on the carbon cloth fiber through a one-step hydrothermal reaction. - ,CO3 2-) negative charge and the positive charge of the amine group (-NH2) in dopamine hydrochloride, to achieve in-situ coating of polydopamine on the surface of the manganese-doped nickel-cobalt precursor at room temperature, and then obtain the target product through sulfurization and carbonization. Manganese-doped nickel-cobalt sulfide is in-situ grown on carbon cloth, and has the outstanding advantages of light weight, small size, and strong deformation resistance. In addition, manganese-doped nickel-cobalt sulfide is firmly bonded to the carbon cloth substrate and can be directly used as a working electrode. Compared with the preparation process of powder-type electrode materials, the present invention does not require solvent and adhesive mixing, nor does it require operations such as stirring, coating and drying, which saves the time for electrode preparation. At the same time, it avoids the problem that the electrode material obtained by the traditional preparation method has uneven coating of the electrode material and the weak bonding of the active material to the substrate during the preparation of the electrode, resulting in the active material falling off the substrate surface during the test and the low repeatability and poor stability of the results.

[0016] (2) The present invention inserts manganese into the precursor, and adjusts the local configuration and electron formation heterostructure around cobalt and nickel atoms through manganese doping, optimizes the electronic state density to improve the intrinsic conductivity of nickel cobalt sulfide, thereby improving the surface electrochemical activity and electron / ion transport of the electrode material.

[0017] (3) The carbon ball layer, as an excellent conductive substrate, is coated on the surface of the high specific capacity manganese-doped nickel cobalt sulfide, which can accelerate the electronic conduction rate of the nickel cobalt sulfide and provide abundant reactive active sites to accelerate the OH in the electrolyte. - Diffusion and Ni 2+ / Co 2+ / Mn 2+ Ion and OH - The kinetics of ion transport during the redox reaction between the electrodes is beneficial to improving the structural stability of the electrode material and inhibiting the volume expansion of the active material during the cycle, so as to better play the synergistic effect of the high theoretical specific capacity of nickel cobalt sulfide and the excellent conductivity of carbon materials, and make up for the defects of poor conductivity of nickel cobalt sulfide and low specific capacity of carbon materials. The thickness of the carbon ball layer can be effectively controlled by adjusting the polydopamine coating time, and the energy storage electrode material with the best conductivity and electrochemical active sites can be optimized and synthesized for use in hybrid solid-state supercapacitors. Compared with the manganese-doped nickel cobalt sulfide / CC electrode not coated with the carbon ball layer, the manganese-doped nickel cobalt sulfide@carbon ball / CC electrode prepared by the present invention has relatively excellent specific capacity and rate performance, can maintain good cycle stability, and can be applied to hybrid solid-state flexible supercapacitors.

[0018] (4) The preparation method of the present invention is simple and repeatable, has low raw material cost, and is universal. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The following are SEM images of the surface morphology of the carbon cloth used in Example 1 before (a) and after (b) the pretreatment in step (1).

[0020] Figure 2 3 are SEM images of the manganese-doped nickel-cobalt precursor / CC prepared in step (2) of Example 2 at different magnifications.

[0021] Figure 3 These are SEM images of the manganese-doped nickel-cobalt sulfide / CC prepared in step (3) of comparative example 1 at different magnifications.

[0022] Figure 4 : These are SEM images of manganese-doped nickel cobalt sulfide @PDA / CC prepared in step (4) of Example 4 at different magnifications.

[0023] Figure 5 : are SEM images of manganese-doped nickel cobalt sulfide@carbon ball / CC prepared in step (5) of Example 4 at different magnifications.

[0024] Figure 6 It is the XRD curve of the manganese-doped nickel cobalt sulfide @ carbon ball / CC prepared in Example 4, the manganese-doped nickel cobalt sulfide / CC prepared in Comparative Example 1, and the pretreated carbon cloth CC.

[0025] 7 is a full XPS spectrum of the manganese-doped nickel cobalt sulfide@carbon ball / CC prepared in Example 4 and the manganese-doped nickel cobalt sulfide / CC electrode material prepared in Comparative Example 1.

[0026] Figure 8 CV curves of the manganese-doped nickel cobalt sulfide / CC electrode material prepared in Comparative Example 1 at different scanning rates.

[0027] Fig. 9 CV curves of the manganese-doped nickel cobalt sulfide@carbon ball / CC electrode material prepared in Example 4 at different scanning rates.

[0028] Fig.10 The electrode materials prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were subjected to a current density of 1 mA / cm 2 Comparison of constant current charge and discharge (GCD) curves under.

[0029] Fig.11 It is the GCD curve of the manganese-doped nickel cobalt sulfide@carbon ball / CC electrode material prepared in Example 4 at different current densities.

[0030] Fig.12 3 is the GCD curve of the manganese-doped nickel cobalt sulfide / CC electrode material prepared in Comparative Example 1 at different current densities.

[0031] Fig.13The manganese-doped nickel cobalt sulfide@carbon ball / CC electrode material prepared in Example 4 and the manganese-doped nickel cobalt sulfide / CC electrode material prepared in Comparative Example 1 were subjected to a current density of 5 mA / cm 2 Comparison of specific capacitance retention rate after 5000 charge and discharge cycles. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The present invention is described in detail with specific examples below. If no specific conditions are specified in the following examples, they are all carried out according to conventional conditions or conditions recommended by the manufacturer. The raw materials and reagents used without specifying the manufacturer are all conventional products that can be purchased from the market.

[0034] Embodiment 1: (1) Pretreatment of carbon cloth (CC): Prepare a carbon cloth with a size of 15×20×0.5mm 3 The carbon cloth was ultrasonically washed with anhydrous ethanol and acetone for 20 min in turn, dried in a drying oven at 60 °C for 12 h, and then immersed in a concentrated sulfuric acid solution (the mass fraction of concentrated sulfuric acid is 98%) for 8 h. The soaked CC was taken out and washed with deionized water for several times, then dried in a drying oven at 60 °C for 12 h, and finally placed in a Ma Fei furnace, heated to 450 °C at a rate of 5 °C / min, and calcined for 5 h. After calcination, it was naturally cooled to room temperature to obtain the pretreated CC.

[0035] (2) Preparation of manganese-doped nickel-cobalt precursor / CC: 0.238 g nickel chloride hexahydrate, 0.476 g cobalt chloride hexahydrate, and 0.099 g manganese chloride tetrahydrate were dissolved in 50 mL deionized water under stirring to obtain a metal ion mixture, 0.24 g urea and 0.072 g ammonium fluoride were added to the metal ion mixture, and stirred until completely dissolved to form solution A. The CC pretreated in step (1) was immersed in solution A and allowed to stand for 4 h, and then all transferred to a hydrothermal reactor, which was placed in a 120°C oven for hydrothermal reaction for 8 h. After the hydrothermal reaction was completed, the carbon cloth CC was naturally cooled to room temperature, and the carbon cloth CC reacted in solution A was taken out and washed with deionized water 3 times, and then placed in a vacuum oven at 60°C for 12 h to obtain a manganese-doped nickel-cobalt precursor in the form of nano needles grown in situ on the carbon cloth, which was recorded as manganese-doped nickel-cobalt precursor / CC.

[0036] (3) Preparation of manganese-doped nickel-cobalt precursor @PDA / CC: 0.0726 g of tris(hydroxymethyl)aminomethane was added to 60 mL of ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and the mixture was dissolved and stirred evenly. Ammonia water was added dropwise to adjust the pH value of the solution to 8.5. Then, 0.2 g of dopamine hydrochloride was added thereto to dissolve the mixture, and solution B was obtained. The manganese-doped nickel-cobalt precursor / CC obtained in step (2) was placed in solution B and allowed to stand at room temperature for self-polymerization reaction for 24 h. The carbon cloth CC after the reaction in solution B was taken out and washed with deionized water for 3 times, and then placed in a vacuum oven and dried at 60°C for 12 h to obtain a carbon cloth with polydopamine in situ coated on the surface of the manganese-doped nickel-cobalt precursor, which was recorded as manganese-doped nickel-cobalt precursor @PDA / CC.

[0037] (4) Preparation of manganese-doped nickel cobalt sulfide @PDA / CC: 2.4 g of sodium sulfide nonahydrate was dissolved in 50 mL of deionized water to form solution C. The manganese-doped nickel cobalt precursor @PDA / CC obtained in step (3) was immersed in solution C and transferred to a hydrothermal reactor. The hydrothermal reactor was placed in an oven at 160°C for hydrothermal sulfurization reaction for 6 h. After the reaction was completed, it was naturally cooled to room temperature. The carbon cloth CC after the reaction in solution C was taken out and washed with deionized water three times, and then placed in an oven at 60°C for 12 h to obtain manganese-doped nickel cobalt sulfide @PDA / CC.

[0038] (5) Preparation of manganese-doped nickel cobalt sulfide@carbon ball / CC: The manganese-doped nickel cobalt sulfide@PDA / CC obtained in step (4) was calcined and carbonized in an argon atmosphere at a temperature of 500°C, a heating rate of 2°C / min, and a holding time of 120 min. After the calcination, the material was naturally cooled to room temperature and taken out to obtain a nano-carbon ball-coated manganese-doped nickel cobalt sulfide / carbon cloth flexible electrode material, which was recorded as manganese-doped nickel cobalt sulfide@carbon ball / CC.

[0039] The manganese-doped nickel-cobalt sulfide@carbon ball / CC prepared in step (5) was used as the working electrode, the platinum electrode as the counter electrode, and the Hg / HgO electrode as the reference electrode. Cyclic voltammetry (CV), constant current charge and discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycle stability tests were performed at different scan rates in 6 mol / L KOH electrolyte. The 1 mA / cm 2 The area specific capacitance is 2987.4 mF / cm 2 , 30 mA / cm 2 The area specific capacitance is 2226.0 mF / cm 2 The rate performance is 74.5%, and the area specific capacitance retention rate after 5000 cycles is 90.8%.

[0040] Embodiment 2: (1) Pretreatment of carbon cloth (CC): The specific operation is the same as step (1) of Example 1.

[0041] (2) Preparation of manganese-doped nickel-cobalt precursor / CC: 0.238 g of nickel chloride hexahydrate and 0.476 g of cobalt chloride hexahydrate were replaced with 0.293 g of nickel nitrate hexahydrate and 0.586 g of cobalt nitrate hexahydrate. The remaining operations were the same as step (2) of Example 1.

[0042] (3) Preparation of manganese-doped nickel-cobalt precursor @PDA / CC: The volume ratio of ethanol to water in the ethanol aqueous solution was 1:2, the self-polymerization reaction time was 48 h, and a new solution B was replaced every 24 h. The remaining operations were the same as step (3) of Example 1.

[0043] (4) Preparation of manganese-doped nickel cobalt sulfide @PDA / CC: The specific operation is the same as step (4) of Example 1.

[0044] (5) Preparation of manganese-doped nickel-cobalt sulfide@carbon ball / CC: The calcination temperature is 550°C, and the remaining operations are the same as step (5) of Example 1.

[0045] The manganese-doped nickel-cobalt sulfide@carbon ball / CC prepared in step (5) was used as the working electrode, the platinum electrode as the counter electrode, and the Hg / HgO electrode as the reference electrode. Cyclic voltammetry (CV), constant current charge and discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycle stability tests were performed at different scan rates in 6 mol / L KOH electrolyte. The 1 mA / cm 2 The area specific capacitance is 3192.1 mF / cm 2 , 30 mA / cm 2 The area specific capacitance is 2556.8 mF / cm 2 The rate performance is 80.1%, and the area specific capacitance retention rate after 5000 cycles is 94.0%.

[0046] Embodiment 3: (1) Pretreatment of carbon cloth (CC): concentrated sulfuric acid was replaced by concentrated nitric acid with a mass fraction of 68%, the calcination temperature was 400° C., and the remaining operations were the same as step (1) of Example 1.

[0047] (2) Preparation of manganese-doped nickel-cobalt precursor / CC: 0.238 g nickel chloride hexahydrate and 0.476 g cobalt chloride hexahydrate were replaced with 0.297 g nickel nitrate hexahydrate and 0.593 g cobalt nitrate hexahydrate. The remaining operations were the same as step (2) of Example 1.

[0048] (3) Preparation of manganese-doped nickel-cobalt precursor @PDA / CC: The volume ratio of ethanol to water in the ethanol aqueous solution was 1:2, the self-polymerization reaction time was 72 h, and a new solution B was replaced every 24 h. The remaining operations were the same as step (3) of Example 1.

[0049] (4) Preparation of manganese-doped nickel cobalt sulfide @PDA / CC: The specific operation is the same as step (4) of Example 1.

[0050] (5) Preparation of manganese-doped nickel-cobalt sulfide@carbon ball / CC: The calcination temperature is 600°C, and the remaining operations are the same as step (5) of Example 1.

[0051] The manganese-doped nickel-cobalt sulfide@carbon ball / CC prepared in step (5) was used as the working electrode, the platinum electrode as the counter electrode, and the Hg / HgO electrode as the reference electrode. Cyclic voltammetry (CV), constant current charge and discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycle stability tests were performed at different scan rates in 6 mol / L KOH electrolyte. The 1 mA / cm 2 The area specific capacitance is 3538.4 mF / cm 2 , 30 mA / cm 2 The area specific capacitance is 2905.0 mF / cm 2 The rate performance is 82.1%, and the area specific capacitance retention rate after 5000 cycles is 95.5%.

[0052] Embodiment 4: (1) Pretreatment of carbon cloth (CC): The specific operation is the same as step (1) of Example 1.

[0053] (2) Preparation of manganese-doped nickel-cobalt precursor / CC: The specific operation is the same as step (2) of Example 1.

[0054] (3) Preparation of manganese-doped nickel-cobalt precursor @PDA / CC: The volume ratio of ethanol to water in the ethanol aqueous solution was 1:2, the self-polymerization reaction time was 96 h, and new solution B was replaced every 24 h. The remaining operations were the same as step (3) of Example 1.

[0055] (4) Preparation of manganese-doped nickel cobalt sulfide @PDA / CC: The specific operation is the same as step (4) of Example 1.

[0056] (5) Preparation of manganese-doped nickel-cobalt sulfide@carbon ball / CC: The calcination temperature is 600°C, and the remaining operations are the same as step (5) of Example 1.

[0057] The manganese-doped nickel-cobalt sulfide@carbon ball / CC prepared in step (5) was used as the working electrode, the platinum electrode as the counter electrode, and the Hg / HgO electrode as the reference electrode. Cyclic voltammetry (CV), constant current charge and discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycle stability tests were performed at different scan rates in 6 mol / L KOH electrolyte. The 1 mA / cm 2 The area specific capacitance is 4324.1 mF / cm 2 , 30 mA / cm 2 The area specific capacitance is 3645.0 mF / cm 2 The rate performance is 84.3%, and the area specific capacitance retention rate after 5000 cycles is 97.2%.

[0058] Comparative Example 1: (1) Pretreatment of carbon cloth (CC): The specific operation is the same as step (1) of Example 1.

[0059] (2) Preparation of manganese-doped nickel-cobalt precursor / CC: The specific operation is the same as step (2) of Example 1.

[0060] (3) Preparation of manganese-doped nickel cobalt sulfide / CC: 2.4 g of sodium sulfide nonahydrate was dissolved in 50 mL of deionized water to form solution C. The manganese-doped nickel cobalt precursor / CC obtained in step (2) was immersed in solution C and all transferred to a hydrothermal reactor. The hydrothermal sulfidation reaction was carried out in an oven at 160°C for 6 h. After the reaction was completed, the carbon cloth CC after the reaction in solution C was taken out and washed with deionized water for 3 times. Then, it was placed in an oven and dried at 60°C for 12 h to obtain a manganese-doped nickel cobalt sulfide / CC electrode material.

[0061] The manganese-doped nickel-cobalt sulfide / CC flexible electrode material prepared in step (3) was used as the working electrode, the platinum electrode as the counter electrode, and the Hg / HgO electrode as the reference electrode. Cyclic voltammetry (CV), constant current charge and discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycle stability tests were performed at different scan rates in 6 mol / L KOH electrolyte. Based on the GCD curve, 1 mA / cm 2 The area specific capacitance is 2724.0 mF / cm 2 , 30 mA / cm 2 When the area specific capacitance is 1968.1 mF / cm 2 The rate performance is 72.3%, and the area specific capacitance retention rate after 5000 cycles is 83.5%.

[0062] The above-mentioned comparative example 1 is a manganese-doped nickel cobalt sulfide / CC flexible electrode material prepared by a two-step hydrothermal reaction, and a carbon ball layer is not coated on the surface of the manganese-doped nickel cobalt compound.

[0063] Comparative Example 2: (1) Pretreatment of carbon cloth (CC): The specific operation is the same as step (1) of Example 1.

[0064] (2) Preparation of nickel-cobalt precursor / CC: 0.238 g nickel chloride hexahydrate and 0.476 g cobalt chloride hexahydrate were dissolved in 50 mL deionized water under stirring to obtain a metal ion mixed solution (excluding manganese ions), 0.24 g urea and 0.072 g ammonium fluoride were added to the metal ion mixed solution, and stirred until completely dissolved to form solution A. The remaining operations were the same as step (2) of Example 1 to obtain a nickel-cobalt precursor / CC.

[0065] (3) Preparation of nickel-cobalt precursor @PDA / CC: 0.0726 g of tris(hydroxymethyl)aminomethane was added to 60 mL of ethanol aqueous solution (the volume ratio of ethanol to water was 1:2), and the mixture was dissolved and stirred evenly. Ammonia water was added dropwise to adjust the pH value of the solution to 8.5. Then, 0.2 g of dopamine hydrochloride was added thereto to dissolve the solution, and solution B was obtained. The nickel-cobalt precursor / CC obtained in step (2) was placed in solution B, and allowed to stand at room temperature for self-polymerization reaction for 96 h. A new solution B was replaced every 24 h. The carbon cloth CC after the reaction in solution B was taken out and washed with deionized water for 3 times, and then placed in a vacuum oven and dried at 60 °C for 12 h to obtain a carbon cloth with polydopamine in situ coated on the surface of the nickel-cobalt precursor, which was recorded as nickel-cobalt precursor @PDA / CC.

[0066] (4) Preparation of nickel cobalt sulfide @PDA / CC: The specific operation is the same as step (4) of Example 1, except that the nickel cobalt precursor @PDA / CC prepared in step (3) of Comparative Example 2 is immersed in solution C (sodium sulfide aqueous solution) to finally obtain nickel cobalt sulfide @PDA / CC.

[0067] (5) Preparation of nickel cobalt sulfide @ carbon ball / CC: The nickel cobalt sulfide @ PDA / CC obtained in step (4) of comparative example 2 was calcined and carbonized under an argon atmosphere at a calcination temperature of 600 ° C, a heating rate of 2 ° C / min, and a holding time of 120 min. After the calcination, it was naturally cooled to room temperature and taken out to obtain a carbon ball-coated nickel cobalt sulfide / CC flexible electrode material, which was labeled as nickel cobalt sulfide @ carbon ball / CC.

[0068] The nickel cobalt sulfide@carbon ball / CC flexible electrode material prepared in step (5) was used as the working electrode, the platinum electrode as the counter electrode, and the Hg / HgO electrode as the reference electrode. Cyclic voltammetry (CV), constant current charge and discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycle stability tests were performed at different scan rates in 6 mol / L KOH electrolyte. Based on the GCD curve, 1 mA / cm 2The area specific capacitance is 3847.6 mF / cm 2 , 30 mA / cm 2 When the area specific capacitance is 3093.5 mF / cm 2 The rate performance is 80.4%, and the area specific capacitance retention rate after 5000 cycles is 95.8%.

[0069] The electrode material prepared in the above comparative example 2 is not doped with manganese element.

[0070] The morphology changes of the intermediate materials and the final electrode materials prepared in the examples and comparative examples were characterized using a German ZEISS Sigma 360 scanning electron microscope (SEM). 2 For small pieces, there is no need to distinguish the front and back sides. They can be glued to the conductive glue on the sample stage and then sprayed with gold for testing.

[0071] Figure 1 The SEM images of the surface morphology of the carbon cloth used in Example 1 before (a) and after (b) pretreatment in step (1), are magnified at 5K times. It can be seen that the surface of the carbon cloth fiber is smooth before pretreatment, and after pretreatment with concentrated acid solution and calcination in air atmosphere, the surface of the carbon cloth fiber becomes rough and cracked, which is conducive to increasing the hydrophilicity of the carbon cloth surface, increasing the loading amount of active materials and making the bonding stronger.

[0072] Figure 2 3 are SEM images of the manganese-doped nickel-cobalt precursor / CC prepared in step (2) of Example 2 at different magnifications. Figure 2 The magnification of (a) is 20k times. Figure 2 The magnification of (b) is 2k times. Figure 2 It shows that after the hydrothermal reaction in step (2), the nano-needle-shaped manganese-doped nickel-cobalt precursor is in-situ uniformly grown on the pretreated carbon cloth fiber. The surface of the nano-needle is very smooth and the diameter of the nano-needle is about 40~100 nm.

[0073] Figure 3 These are SEM images of the manganese-doped nickel-cobalt sulfide / CC prepared in step (3) of comparative example 1 at different magnifications. Figure 3 The magnification of (a) is 20k times. Figure 3 The magnification of (b) is 2k times. Figure 3 It shows that after the ion exchange reaction occurs during the hydrothermal vulcanization process, the manganese-doped nickel-cobalt sulfide generated still maintains the nanoneedle morphology and grows evenly on the carbon cloth fibers, but the surface of the nanoneedle becomes rough.

[0074] Figure 4are SEM images of manganese-doped nickel-cobalt sulfide @PDA / CC prepared in step (4) of Example 4 at different magnifications. Figure 4 The magnification of (a) is 1k times. Figure 4 The magnification of (b) is 2k times. Figure 4 The magnification of the middle (c) is 20k times. Figure 4 The magnification of (d) is 100k times. It can be seen from the figure that compared with the manganese-doped nickel cobalt sulfide nanoneedles ( Figure 3 ), after being coated with polydopamine and then subjected to a hydrothermal vulcanization process, the surface of the nanoneedles was covered with spherical polydopamine particles, and the nanoneedles were slightly aggregated.

[0075] Figure 5 is the SEM image of the manganese-doped nickel-cobalt sulfide@carbon ball / CC prepared in step (5) of Example 4 at different magnifications, Figure 5 The magnification of (a) is 1k times. Figure 5 The magnification of (b) is 5k times. Figure 5 The magnification of (c) is 30k times. Figure 5 The magnification of (d) is 100k times. It can be seen from the figure that the manganese-doped nickel-cobalt sulfide coated with spherical polydopamine particles still retains the nanoneedle morphology after calcination, grows in situ on the surface of the carbon cloth, and the aggregation phenomenon disappears. The surface of each nanoneedle is coated with a carbon ball layer. The diameter of the nanoneedle is about 40~100 nm, and the particle size of the carbon ball is about 10~50 nm. The high conductivity and high specific surface area of ​​the carbon ball layer can increase the active material and OH in the electrolyte. - The contact area provides more active sites for redox reactions, giving full play to the synergistic effect of the high theoretical specific capacity of manganese-doped nickel cobalt sulfide and the excellent conductivity of carbon materials, making up for the defects of poor conductivity of nickel cobalt sulfide and low specific capacity of carbon materials.

[0076] The XRD test was performed using a Japanese Rigaku SmartLab SE X-ray diffractometer, and the carbon cloth loaded with active materials was placed on a sample table to analyze information such as the composition and crystal structure of the material. Figure 6The XRD curves of the manganese-doped nickel cobalt sulfide @ carbon ball / CC prepared in Example 4, the manganese-doped nickel cobalt sulfide / CC prepared in Comparative Example 1, and the pretreated carbon cloth CC. By comparison, it was found that the XRD curves of the manganese-doped nickel cobalt sulfide @ carbon ball / CC prepared in Example 4 and the manganese-doped nickel cobalt sulfide / CC prepared in Comparative Example 1 both showed characteristic peaks of NiCo2S4 and CC. Among them, 2θ at 26.8°, 31.5°, 38.3°, 50.4°, 55.3°, 65.0°, 69.2° and 78.1° correspond to the (220), (311), (400), (511), (440), (533), (444) and (731) crystal planes of NiCo2S4, respectively. In addition, from the XRD curve of Example 4, it can be seen that the diffraction peak of Co9S8 also appears in the manganese-doped nickel-cobalt sulfide@carbon ball / CC electrode material prepared by polydopamine coating and calcination process, and 2θ at 15.4°, 29.8°, 47.5° and 52.05° corresponds to the (111), (311), (511) and (440) crystal planes of Co9S8, respectively, indicating that the loaded nickel-cobalt sulfide product contains Co9S8 and NiCo2S4. Due to the small amount of manganese doping, it was not observed in the comparative example and Example 4.

[0077] XPS testing was performed using a Thermo Scientific K-Alpha X-ray photoelectron spectrometer from the United States. The carbon cloth loaded with active materials was placed on a sample stage to analyze the valence state of the elements in the electrode and possible bonding interactions. Figure 7 It is the full XPS spectrum of the manganese-doped nickel cobalt sulfide@carbon ball / CC prepared in Example 4 and the manganese-doped nickel cobalt sulfide / CC electrode material prepared in Comparative Example 1. Figure 7 It shows that the electrodes all contain Ni, Co, Mn, S, C, and O elements, but the N1s energy band at 399.1 eV and the C1s energy band at 284.8 eV in Example 4 are stronger than those in Comparative Example 1, indicating that the coated polydopamine forms a carbon ball layer coated on the surface of manganese-doped nickel cobalt sulfide after calcination.

[0078] The material was subjected to a three-electrode test using a Shanghai Chenhua electrochemical workstation CHI760E, with the manganese-doped nickel cobalt sulfide@carbon ball / CC electrode material prepared in Example 4 or the manganese-doped nickel cobalt sulfide / CC electrode material prepared in Comparative Example 1 as the working electrode, a platinum sheet electrode as the counter electrode; and a Hg / HgO electrode as the reference electrode. Cyclic voltammetry (CV) test analysis was performed at different scan rates in a 6 mol / L KOH electrolyte. Figure 8 and Fig. 9 The CV curves of the electrode materials prepared in Comparative Example 1 and Example 4 at different scanning rates are shown in FIG. Figure 8It can be seen that: when the scan rate increases from 2 mV / s to 20 mV / s, the shape of the CV curve of the manganese-doped nickel cobalt sulfide / CC electrode material prepared in Comparative Example 1 can remain consistent, but when it continues to increase to 50 mV / s and 100 mV / s, the CV curve is severely deformed. Fig. 9 In the experiment, the scan rate increased from 2 mV / s to 200 mV / s, and the CV curve shape of the manganese-doped nickel cobalt sulfide@carbon ball / CC electrode material prepared in Example 4 remained consistent, indicating that coating the carbon ball layer on the surface of manganese-doped nickel cobalt sulfide can improve the rate performance of the electrode.

[0079] Fig.10 The electrode materials prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were subjected to a current density of 1 mA / cm 2 Comparison of constant current charge and discharge (GCD) curves under the current density of 1 mA / cm 2 When the area specific capacitance of the electrode materials prepared in Example 1, Example 2, Example 3, Example 4 and Comparative Example 1 and Comparative Example 2 is 2987.4 mF / cm 2 、3192.1 mF / cm 2 、3538.4 mF / cm 2 、4324.1 mF / cm 2 and 2724.0 mF / cm 2 、3847.6 mF / cm 2 Compared with the comparative example 1 without the carbon ball layer, coating the carbon ball layer on the surface of the manganese-doped nickel cobalt sulfide can significantly improve the specific capacitance of the electrode material. The area specific capacitance of the electrode material obtained with a coating time of 96 h in Example 4 is the largest, indicating that an excellent coating effect has been achieved. Compared with the nickel cobalt sulfide@carbon ball / CC prepared by coating polydopamine for 96 h without manganese element in comparative example 2, manganese element doping improves the specific capacitance of the electrode, indicating that manganese atom doping can adjust the local configuration and electron formation heterogeneous structure around nickel and cobalt atoms, optimize the electronic state density, give full play to the synergistic effect between metal ions, and provide abundant electrochemical active sites.

[0080] Fig.11 The GCD curves of the manganese-doped nickel-cobalt sulfide@carbon ball / CC electrode material prepared in Example 4 at different current densities are shown in Table 1. 2 When the area specific capacitance of the electrode material is 4324.1 mF / cm 2 When the current density increases to 30 mA / cm 2 When the area specific capacitance of the electrode material is 3645.0 mF / cm 2 , the rate performance is 84.3%.

[0081] Fig.12 The GCD curves of the manganese-doped nickel-cobalt sulfide / CC electrode material prepared in Comparative Example 1 at different current densities are shown in Table 1. 2 When the area specific capacitance of the electrode material is 2724.0 mF / cm 2 When the current density increases to 30 mA / cm 2 When the area specific capacitance of the electrode material is 1968.1 mF / cm 2 , the rate performance is 72.3%.

[0082] contrast Fig.11 and Fig.12 It can be seen that after the surface of manganese-doped nickel-cobalt sulfide is coated with a carbon ball layer, the excellent conductivity and large specific surface area of ​​the carbon ball layer can increase the contact with the electrolyte OH - The contact area can provide more active sites for redox reactions, giving full play to the synergistic effect of the high theoretical specific capacity of manganese-doped cobalt nickel sulfide and the excellent conductivity of carbon materials, so that the area specific capacitance and rate performance of the prepared electrode are significantly improved.

[0083] Fig.13 The electrode materials prepared in Example 4 and Comparative Example 1 were subjected to a current density of 5 mA / cm 2 The capacitance retention rate comparison chart of the specific capacitance after 5000 cycles of charge and discharge is shown in Figure 4. The capacitance retention rate of the manganese-doped nickel cobalt sulfide@carbon ball / CC electrode material prepared in Example 4 after 5000 cycles is 97.2%, which is significantly better than the capacitance retention rate of 83.5% of the manganese-doped nickel cobalt sulfide / CC electrode material prepared in Comparative Example 1, indicating that the coating of the carbon ball layer can significantly improve the cycle stability of the manganese-doped nickel cobalt sulfide / CC electrode.

[0084] The nano-carbon ball coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material disclosed in the present invention uses the pretreated carbon cloth as a substrate, firstly grows a manganese-doped nickel-cobalt precursor in situ on the surface of the carbon cloth through a hydrothermal reaction, then realizes in situ coating of polydopamine on the surface of the manganese-doped nickel-cobalt precursor at room temperature in an ethanol / water solution containing trishydroxymethylaminomethane and dopamine hydrochloride, and then undergoes a hydrothermal ion exchange to undergo a sulfidation reaction to obtain a carbon cloth coated with polydopamine manganese-doped nickel-cobalt sulfide, and finally obtains a carbon cloth flexible electrode material coated with a carbon ball layer manganese-doped nickel-cobalt sulfide after polydopamine is decomposed and carbonized in a calcination process. The present invention adjusts the local configuration around cobalt and nickel atoms and the electrons form a heterogeneous structure through manganese doping, can optimize the electronic state density, improve the intrinsic conductivity of nickel-cobalt sulfide, and thus improve the surface electrochemical activity and electron / ion transmission of the electrode material. The carbon sphere layer coated on the surface of manganese-doped nickel cobalt sulfide has high conductivity and high specific surface area, which can accelerate the electronic conduction rate of nickel cobalt sulfide. At the same time, it can provide abundant reaction active sites, accelerate the kinetics of ion transfer during redox reactions, and help improve the structural stability of electrode materials and inhibit the volume expansion of active substances during the cycle, so as to better play the synergistic effect of the high theoretical specific capacity of nickel cobalt sulfide and the excellent conductivity of carbon materials, and make up for the defects of poor conductivity of nickel cobalt sulfide and low specific capacity of carbon materials.

[0085] The above is only an embodiment of the present invention, and does not limit the present invention in any form. The present invention can also have other forms of embodiments according to the above structures and functions, which are not listed one by one. Therefore, any simple modification, equivalent change and modification made by any technician familiar with the profession to the above embodiment according to the technical essence of the present invention without departing from the scope of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material, characterized in that: Manganese-doped nickel-cobalt sulfide is in-situ grown on the surface of the carbon cloth. The manganese-doped nickel-cobalt sulfide is in the shape of nano needles, and the surface of each nano needle is coated with a carbon ball layer.

2. The nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material according to claim 1, characterized in that: The diameter of the nanoneedles is 40~100 nm, and the particle size of the carbon spheres is 10~50 nm.

3. A method for preparing a nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material, characterized in that: The following steps are involved: (1) Pretreatment of carbon cloth CC; (2) Preparation of manganese-doped nickel-cobalt precursor / CC: dissolving hydrated nickel salt, hydrated cobalt salt and hydrated manganese salt in deionized water to obtain a metal ion mixture, adding urea and ammonium fluoride to the metal ion mixture, stirring until dissolved, and forming solution A; immersing the carbon cloth CC pretreated in step (1) in solution A and standing for 4 to 6 hours, then transferring it to a hydrothermal reactor for hydrothermal reaction, and naturally cooling to room temperature after the reaction, taking out the reacted carbon cloth, washing it with deionized water, and then drying it to obtain a nano-needle-shaped manganese-doped nickel-cobalt precursor grown in situ on the carbon cloth, which is recorded as manganese-doped nickel-cobalt precursor / CC; (3) Preparation of manganese-doped nickel-cobalt precursor @PDA / CC: Add tris(hydroxymethyl)aminomethane to an ethanol aqueous solution and stir to dissolve the mixture, adjust the pH value of the solution to 8.5, and then add dopamine hydrochloride to dissolve the mixture to obtain solution B; place the manganese-doped nickel-cobalt precursor / CC obtained in step (2) into solution B, and allow the mixture to react at room temperature for 24 to 96 h, replace solution B every 24 h, take out the carbon cloth after the reaction, wash it with deionized water, and then dry it to obtain a carbon cloth with polydopamine in situ coated on the surface of the manganese-doped nickel-cobalt precursor, which is recorded as manganese-doped nickel-cobalt precursor @PDA / CC; (4) Preparation of manganese-doped nickel-cobalt sulfide @PDA / CC: dissolving sodium sulfide nonahydrate in deionized water to form a solution C, immersing the manganese-doped nickel-cobalt precursor @PDA / CC obtained in step (3) in the solution C and transferring the whole of the solution into a hydrothermal reactor for a hydrothermal sulfidation reaction. After the reaction is completed, the mixture is naturally cooled to room temperature. The carbon cloth after the reaction is taken out, washed with deionized water, and then dried to obtain manganese-doped nickel-cobalt sulfide @PDA / CC; (5) Preparation of manganese-doped nickel cobalt sulfide@carbon ball / CC: The manganese-doped nickel cobalt sulfide@PDA / CC obtained in step (4) was calcined in an argon atmosphere at a calcination temperature of 500-600°C, a heating rate of 2°C / min, and a holding time of 60-180 min. After the calcination, it was naturally cooled to room temperature and taken out to obtain a nano-carbon ball-coated manganese-doped nickel cobalt sulfide / carbon cloth flexible electrode material, which was recorded as manganese-doped nickel cobalt sulfide@carbon ball / CC.

4. The method for preparing the nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material according to claim 3, characterized in that: The pretreatment process of the carbon cloth in step (1) includes: ultrasonically washing the carbon cloth with anhydrous ethanol and acetone in sequence, placing it in a drying oven for drying, and then immersing it in concentrated sulfuric acid or concentrated nitric acid for 4 to 12 hours, taking out the soaked carbon cloth and washing it with deionized water for multiple times, placing it in a drying oven for drying, and finally placing it in a Ma Fuel furnace, heating it to 400 to 500° C., roasting it for 2 to 6 hours, and naturally cooling it to room temperature after roasting to obtain the pretreated carbon cloth.

5. The method for preparing the nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material according to claim 3, characterized in that: The hydrated nickel salt in step (2) is selected from one of nickel nitrate hexahydrate and nickel chloride hexahydrate, the hydrated cobalt salt is selected from one of cobalt nitrate hexahydrate and cobalt chloride hexahydrate, and the hydrated manganese salt is selected from manganese chloride tetrahydrate; the temperature of the hydrothermal reaction is 120° C., and the reaction time is 8 h.

6. The method for preparing the nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material according to claim 3 or 5, characterized in that: In step (2), the molar ratio of hydrated nickel salt, hydrated cobalt salt, hydrated manganese salt, urea and ammonium fluoride is 1:2:0.5:4:2, the concentration of hydrated nickel salt in solution A is 0.01-0.03 mol / L, the concentration of hydrated cobalt salt is 0.02-0.06 mol / L, and the concentration of hydrated manganese salt is 0.005-0.015 mol / L.

7. The method for preparing the nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material according to claim 3, characterized in that: In step (3), the concentration of tris(hydroxymethyl)aminomethane in solution B is 0.01 to 0.03 mol / L, the concentration of dopamine hydrochloride is 0.01 to 0.06 mol / L, and the ethanol aqueous solution is obtained by mixing anhydrous ethanol and water, and the volume ratio of anhydrous ethanol to water is 1:1 to 1:

4.

8. The method for preparing the nano-carbon ball-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material according to claim 3, characterized in that: In step (4), the concentration of sodium sulfide nonahydrate in solution C is 0.2-0.6 mol / L, the temperature of the hydrothermal sulfidation reaction is 160° C., and the reaction time is 6-8 h.

9. Application of the nano-carbon sphere-coated manganese-doped nickel-cobalt sulfide / carbon cloth flexible electrode material obtained by the preparation method as claimed in claim 3 as an energy storage electrode material in a supercapacitor.

10. The use according to claim 9, characterized in that: The nano carbon ball coated manganese-doped nickel cobalt sulfide / carbon cloth flexible electrode material is directly used as a working electrode.

Images