NiCo2S4 electrode material with three-dimensional nanostructure as well as preparation method and application of NiCo2S4 electrode material

Abstract

The invention relates to the technical field of electrode materials, in particular to a three-dimensional nanostructure NiCo2S4 electrode material and a preparation method and application thereof. The preparation method of the electrode material comprises the following steps: S1, dissolving a cobalt source and a nickel source in deionized water to obtain a metal salt solution; s2, adding ammonium hydroxide, a surfactant CTAB (cetyltrimethyl ammonium bromide) and an organic sulfur source into the metal salt solution, and uniformly mixing; and S3, carrying out a hydrothermal reaction, and carrying out solid-liquid separation, washing and drying to obtain the NiCo2S4 electrode material with the three-dimensional nanostructure. According to the preparation method disclosed by the invention, the three-dimensional nanostructure NiCo2S4 material which is formed by ultrathin nanosheets and has a high specific surface area is synthesized through a one-step hydrothermal method by utilizing a synergistic effect of ammonium hydroxide, an organic sulfur source and a surfactant CTAB (Cetyltrimethyl Ammonium Bromide); when the material is used as an electrode material, the electrochemical performance of a battery or a supercapacitor can be remarkably improved; and the preparation process is simple and efficient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrode materials, in particular to a three-dimensional nano-structured NiCo2S4 electrode material, a preparation method and application thereof. BACKGROUND

[0002] With the development of lithium ion batteries and the application of power batteries in new energy vehicles, people have higher requirements for power density, cycle life, etc. Compared with lithium ion batteries, supercapacitors have higher power density, longer service life and more green environmental protection. The electrochemical performance of supercapacitors mainly depends on the properties of electrode materials, and the advantages and disadvantages of electrode materials determine the performance of supercapacitors. In order to explore a high-performance electrode material, researchers have conducted in-depth research on various transition metal oxides or sulfides, nitrides and phosphides in the past few decades. However, due to the large volume change of metal sulfides and the easy solubility of polysulfide ions in electrolyte, there are common problems such as low power utilization (i.e. capacity reduction) and short life obstacles.

[0003] Therefore, the present application is proposed. SUMMARY

[0004] The first object of the present application is to provide a preparation method of a three-dimensional nano-structured NiCo2S4 electrode material. The three-dimensional nano-structured NiCo2S4 electrode material with high specific surface area is obtained by one-step hydrothermal method through the synergistic control-sulfuration mechanism of CTAB and organic sulfur source in an alkaline system. The preparation process is simple, the obtained NiCo2S4 electrode material has large specific surface area, and is used in energy storage devices such as lithium ion batteries, sodium ion batteries or supercapacitors, which can significantly improve the electrochemical performance.

[0005] The second object of the present application is to provide a three-dimensional nano-structured NiCo2S4 electrode material prepared by the preparation method of the three-dimensional nano-structured NiCo2S4 electrode material.

[0006] The third object of the present application is to provide a working electrode comprising the three-dimensional nano-structured NiCo2S4 electrode material.

[0007] The fourth object of the present application is to provide the application of the working electrode in the preparation of lithium ion batteries, sodium ion batteries or supercapacitors.

[0008] In order to achieve the above objects of the present application, the following technical solutions are adopted: A preparation method of a three-dimensional nano-structured NiCo2S4 electrode material, comprising the following steps: S1. Dissolve a cobalt source and a nickel source in deionized water to obtain a metal salt solution; S2. Adding ammonium hydroxide, surfactant CTAB and organic sulfur source into the metal salt solution and mixing uniformly; S3. Performing hydrothermal reaction, and obtaining the three-dimensional nano-structured NiCo2S4 electrode material through solid-liquid separation, washing and drying.

[0009] Preferably, the cobalt source comprises at least one of cobalt nitrate hexahydrate, cobalt chloride hexahydrate and cobalt sulfate heptahydrate.

[0010] Preferably, the nickel source comprises at least one of nickel nitrate hexahydrate, nickel chloride hexahydrate and nickel sulfate hexahydrate.

[0011] Preferably, the cobalt source and the nickel source are metered in a molar ratio of Co and Ni of 1.9-2.1:1.

[0012] Preferably, in step S2, after adding the ammonium hydroxide, the pH of the system is 10-11.

[0013] Preferably, the organic sulfur source comprises thiourea and / or thioacetamide.

[0014] Preferably, the molar ratio of the organic sulfur source to the total amount of nickel and cobalt metal is 2.5-3.5:1.

[0015] Preferably, the feeding sequence in step S2 is: first adding the ammonium hydroxide to form a suspension, then adding the CTAB, and finally adding the organic sulfur source.

[0016] Preferably, the molar ratio of the CTAB to the total amount of nickel and cobalt metal is 0.2-0.4:1.

[0017] Preferably, the temperature of the hydrothermal reaction is 120-180℃, and the time of the hydrothermal reaction is 8-12h.

[0018] A three-dimensional nano-structured NiCo2S4 electrode material is prepared by the preparation method of the three-dimensional nano-structured NiCo2S4 electrode material in any one of the preceding embodiments.

[0019] A working electrode comprises the three-dimensional nano-structured NiCo2S4 electrode material in the preceding embodiments.

[0020] The working electrode in the preceding embodiments is applied to the preparation of lithium ion batteries, sodium ion batteries or supercapacitors.

[0021] Compared with the prior art, the present application has the following beneficial effects: The prepared nickel cobalt sulfide (NiCo2S4) has excellent electrochemical performance due to the electrochemical contribution of nickel and cobalt ions; compared with binary metal sulfides of cobalt sulfide and nickel sulfide, the ternary sulfide can provide more abundant redox reactions and higher electronic conductivity; the synergistic effect of ammonium hydroxide, organic sulfur source and surfactant cetyltrimethylammonium bromide (CTAB) is utilized to synthesize the three-dimensional nanostructure NiCo2S4 material with high specific surface area formed by ultrathin nanosheets through one-step hydrothermal method; the material is used as an electrode material, and can significantly improve the electrochemical performance of a battery or a supercapacitor; and the preparation process is simple and efficient. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0023] Figure 1 X-ray diffraction pattern of the NiCo2S4 electrode material prepared for Example 1, Example 2 and Example 3 of the present application; Figure 2 Morphology diagram of the NiCo2S4 electrode material prepared for Example 1 of the present application; Figure 3 Morphology diagram of the NiCo2S4 electrode material prepared for Example 2 of the present application; Figure 4 Morphology diagram of the NiCo2S4 electrode material prepared for Example 3 of the present application; Figure 5 Morphology diagram of the NiCo2S4 electrode material prepared for Comparative Example 1 of the present application; Figure 6 Morphology diagram of the NiCo2S4 electrode material prepared for Comparative Example 2 of the present application; Figure 7 Morphology diagram of the NiCo2S4 electrode material prepared for Comparative Example 3 of the present application. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described clearly and completely below in combination with the drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, and are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market.

[0025] The first aspect of the present application provides a preparation method of a three-dimensional nano-structured NiCo2S4 electrode material, comprising the following steps: S1. Dissolve a cobalt source and a nickel source in deionized water to obtain a metal salt solution; S2. Add ammonium hydroxide, a surfactant CTAB and an organic sulfur source to the metal salt solution and mix uniformly; S3. Perform a hydrothermal reaction, and after solid-liquid separation, washing and drying, obtain a three-dimensional nano-structured NiCo2S4 electrode material.

[0026] As an electrode material, transition metal sulfide material has excellent electrochemical performance, high theoretical specific capacity and perfect preparation process, and at the same time has good thermal stability and mechanical stability, therefore, in recent years, transition metal sulfide has been determined as a substitute electrode material for high-performance supercapacitors. Among them, nickel-based sulfide is widely concerned due to its simple preparation and synthesis, high conductivity and excellent electrochemical performance. According to the different proportions of nickel element and sulfur element, nickel-based sulfide can be divided into various types, among which NiS2, Ni3S4 and α-NiS are common energy storage materials, and the energy storage mechanism thereof is as follows:

[0027] Similar to nickel-based sulfide, cobalt-based sulfide has a rich chemical structure due to the variety of stoichiometric composition, among which Co9S8, CoS and CoS2 are widely used as energy storage materials, and the energy storage mechanism thereof is as follows:

[0028] Compared with binary metal sulfides (such as nickel sulfide and cobalt sulfide), ternary sulfides can provide more abundant redox reactions and higher electronic conductivity, and thus have better electrochemical energy storage performance. Compared with binary metal sulfides and ternary metal oxides, NiCo2S4 is more attractive; the main reason is that it can provide more abundant redox reaction sites than cobalt sulfide and nickel sulfide; it has more advantages in high conductivity than NiCo2O4, and has better comprehensive performance.

[0029] However, there are still common problems with transition metal sulfides as electrode materials: large volume change of metal sulfides, and easy dissolution of polysulfide ions in electrolyte, which can cause problems such as low electrical utilization rate and short service life of electrode materials. To solve these problems, preparing nanostructured electrode materials is an effective solution - since redox reactions mainly occur on the surface or near the surface of active materials, three-dimensional nanostructured materials with high specific surface area can further improve electrochemical performance (such as inhibiting volume change and reducing the loss caused by polysulfide dissolution) compared with one-dimensional and two-dimensional structured materials.

[0030] Based on this, the present application provides a preparation method of three-dimensional nanostructured NiCo2S4 electrode material, which uses one-step hydrothermal method to prepare NiCo2S4 electrode material, and has simple and efficient process. The synergistic effect of NH3, CTAB and organic sulfur source in alkaline system is used, ammonium hydroxide and metal salt solution form Ni-Co hydroxide suspension, CTAB forms micelles in alkaline suspension, and nickel-cobalt hydroxide precursor is guided to grow into ultrathin nanosheets (thickness less than 10 nm), and organic sulfur source penetrates the gap between micelles to realize in-situ sulfuration, forming mesoporous flower-like structure; three-dimensional nanostructured NiCo2S4 electrode material with high specific surface area formed by ultrathin nanosheets is prepared, which can significantly improve its electrochemical performance.

[0031] In some embodiments of the present application, the cobalt source includes at least one of cobalt nitrate hexahydrate, cobalt chloride hexahydrate, and cobalt sulfate heptahydrate.

[0032] In some embodiments of the present application, the nickel source includes at least one of nickel nitrate hexahydrate, nickel chloride hexahydrate, and nickel sulfate hexahydrate.

[0033] In some embodiments of the present application, the cobalt source and the nickel source are metered in a molar ratio of Co to Ni of 1.9-2.1:1, for example, the molar ratio of Co to Ni can be any one value or a range value composed of any two point values in 1.9:1, 1.95:1, 2:1, 2.05:1, and 2.1:1.

[0034] In some embodiments of the present application, in step S1, the total concentration of metal ions in the metal salt solution is 20-30 mmol / L, for example, it can be any one value or a range value consisting of any two point values among 20 mmol / L, 22 mmol / L, 25 mmol / L, 28 mmol / L and 30 mmol / L.

[0035] In some embodiments of the present application, in step S2, after adding ammonium hydroxide, the pH of the system is 10-11. Ammonium hydroxide is a weak base, and its ionization process is reversible, which can slowly release OH - and stabilize the pH of the system in a suitable range, avoiding local over-alkalization. Such a mild alkaline environment can ensure the gradual reaction of Ni 2+ , Co 2+ and sulfur source, reduce the generation of hydroxide impurities, and provide stable conditions for the ordered growth of three-dimensional nanostructures; and NH3 in ammonium hydroxide can "bind" metal ions through coordination, reducing their free concentration, so that metal ions are released at a controllable rate and react with the sulfur source. This "slow release" mechanism can regulate the nucleation rate and growth direction of nanocrystals, making it easier to form three-dimensional porous structures with high specific surface area; the synergistic sulfidation of ammonium hydroxide, CTAB and organic sulfur source is conducive to obtaining three-dimensional nanostructured NiCo2S4 electrode materials with excellent electrochemical performance.

[0036] In some embodiments of the present application, the organic sulfur source includes thiourea and / or thioacetamide.

[0037] In some embodiments of the present application, the molar ratio of the total amount of organic sulfur source to the total amount of nickel and cobalt metal (the total amount of Ni 2+ and Co 2+ added) is 2.5-3.5:1, for example, it can be any one value or a range value consisting of any two point values among 2.5:1, 2.8:1, 3:1, 3.2:1 and 3.5:1.

[0038] In some embodiments of the present application, the feeding sequence in step S2 is: first adding ammonium hydroxide to form a suspension, then adding CTAB, and finally adding an organic sulfur source; after adding ammonium hydroxide, a Ni-Co hydroxide suspension is formed, CTAB forms micelles in the alkaline suspension, guiding the directional growth of nickel-cobalt hydroxide precursors into ultrathin nanosheets, and the organic sulfur source penetrates the micelles to realize in-situ sulfidation, forming a mesoporous flower-like structure. The feeding sequence of the three will affect their action process, and in turn affect the electrochemical performance of the product.

[0039] In some embodiments of the present application, the molar ratio of CTAB to the total amount of nickel and cobalt metal is 0.2-0.4:1, for example, it can be any one value or a range value composed of any two values in 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1; by controlling the addition ratio of CTAB, the present application can obtain NiCo2S4 material with high specific surface area, thereby improving its electrochemical performance.

[0040] In some embodiments of the present application, in step S2, the mixing includes stirring mixing, the temperature of stirring mixing is 40-60℃, for example, it can be any one value or a range value composed of any two values in 40℃, 45℃, 50℃, 55℃, 60℃; the stirring speed of stirring mixing is 300-500rpm, for example, it can be any one value or a range value composed of any two values in 300rpm, 350rpm, 400rpm, 450rpm, 500rpm; the stirring mixing time after the completion of adding all raw materials is 5-15min, for example, it can be any one value or a range value composed of any two values in 5min, 8min, 10min, 12min, 15min.

[0041] In some embodiments of the present application, in step S3, the temperature of hydrothermal reaction is 120-180℃, for example, it can be any one value or a range value composed of any two values in 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃; the time of hydrothermal reaction is 8-12h, for example, it can be any one value or a range value composed of any two values in 8h, 9h, 10h, 11h, 12h.

[0042] The second aspect of the present application provides a three-dimensional nano-structured NiCo2S4 electrode material, which is prepared by the preparation method of the three-dimensional nano-structured NiCo2S4 electrode material in any one of the preceding embodiments, and has a specific surface area of 160-200m 2 / g, for example, it can be any one value or a range value composed of any two values in 160m 2 / g, 168m 2 / g, 183m 2 / g, 197m 2 / g, 200m 2 / g.

[0043] The third aspect of the present application provides a working electrode comprising the three-dimensional nano-structured NiCo2S4 electrode material in the preceding embodiments.

[0044] In some embodiments of the present application, the preparation method of the working electrode comprises the following steps: Step one: the prepared NiCo2S4 electrode material, a binder (such as PVDF), and a conductive agent (such as acetylene black) are uniformly mixed together, and then an appropriate amount of N-methyl pyrrolidone is added and mixed uniformly in a jade mortar to obtain the required paste-like active electrode material; Step two: the foam nickel is cleaned and pretreated and dried, and the paste-like active electrode material obtained in step one is uniformly coated on the foam nickel electrode sheet using a glass rod; Step three: the foam nickel electrode sheet obtained in step two is placed in a drying box for complete drying; Step four: the dried foam nickel electrode sheet obtained in step three is subjected to tabletting treatment using a tablet press to ensure that the active electrode material coating does not fall off or be damaged; Step five: the foam nickel electrode sheet is welded on a nickel strip to obtain the required working electrode.

[0045] The fourth aspect of the present application provides a use of the working electrode described in the foregoing embodiments in the preparation of a lithium ion battery, a sodium ion battery, or a supercapacitor.

[0046] Embodiments of the present application will be described in detail below with reference to specific examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If no manufacturer of the reagent or instrument is specified, it is a conventional product that can be obtained by purchase on the market.

[0047] Example 1 S1. 0.4 mmol (0.116316 g) of Ni(NO3)2·6H2O and 0.8 mmol (0.232824 g) of Co(NO3)2·6H2O were stirred and dissolved in 48 mL of deionized water to obtain a metal salt solution; S2. 1 mL of ammonium hydroxide (analytical pure) was added to the above metal salt solution, the pH of the system was 10-11, a Ni-Co hydroxide suspension was formed, then CTAB was slowly added, the molar ratio of CTAB to the total amount of metal ions was 0.2, and finally 3.6 mmol (0.274032 g) of thiourea was slowly added. The resulting mixture was magnetically stirred at 40℃ for 10 min at a stirring speed of 500 rpm; S3. The stirred mixture of step S2 was transferred to a Teflon-lined stainless steel autoclave, and hydrothermal reaction was carried out at 120℃ for 12 h. After cooling to room temperature, the supernatant in the reaction kettle was poured out, and the black precipitate at the bottom of the reaction kettle was left. Finally, the black precipitate was washed several times by centrifugation with deionized water and ethanol. After washing, the obtained product was vacuum dried at 60℃ for 10 h, and then ground in a mortar to obtain a NiCo2S4 electrode material with a three-dimensional nanostructure.

[0048] Example 2 S1. 0.4 mmol (0.116316 g) of Ni (NO3)2·6H2O and 0.8 mmol (0.232824 g) of Co (NO3)2·6H2O were dissolved in 48 mL of deionized water under stirring to obtain a metal salt solution; S2. 1 mL of ammonium hydroxide (analytical pure) was added to the above metal salt solution, the system pH was 10-11, a Ni-Co hydroxide suspension was formed, then CTAB was slowly added, the molar ratio of CTAB to the total amount of metal ions was 0.3, finally 3.6 mmol (0.274032 g) of thiourea was slowly added, the obtained mixture was stirred at 40°C for 10 min at a stirring speed of 500 rpm; S3. The mixture after stirring in step S2 was transferred to a Teflon-lined stainless steel autoclave, and hydrothermal reaction was carried out at 120°C for 12 h, after cooling to room temperature, the supernatant in the reaction kettle was poured out, the black precipitate at the bottom of the reaction kettle was left, and the black precipitate was washed with deionized water and ethanol for several times; after washing, vacuum drying was carried out at 60°C for 10 h, the obtained product was ground in a mortar to obtain a NiCo2S4 electrode material with three-dimensional nanostructure.

[0049] Example 3 S1. 0.4 mmol (0.116316 g) of Ni (NO3)2·6H2O and 0.8 mmol (0.232824 g) of Co (NO3)2·6H2O were dissolved in 48 mL of deionized water under stirring to obtain a metal salt solution; S2. 1 mL of ammonium hydroxide (analytical pure) was added to the above metal salt solution, the system pH was 10-11, a Ni-Co hydroxide suspension was formed, then CTAB was slowly added, the molar ratio of CTAB to the total amount of metal ions was 0.4, finally 3.6 mmol (0.274032 g) of thiourea was slowly added, the obtained mixture was stirred at 40°C for 10 min at a stirring speed of 500 rpm; S3. The mixture after stirring in step S2 was transferred to a Teflon-lined stainless steel autoclave, and hydrothermal reaction was carried out at 120°C for 12 h, after cooling to room temperature, the supernatant in the reaction kettle was poured out, the black precipitate at the bottom of the reaction kettle was left, and the black precipitate was washed with deionized water and ethanol for several times; after washing, vacuum drying was carried out at 60°C for 10 h, the obtained product was ground in a mortar to obtain a NiCo2S4 electrode material with three-dimensional nanostructure.

[0050] Comparative Example 1 S1. 0.4 mmol (0.116316 g) of Ni (NO3)2·6H2O and 0.8 mmol (0.232824 g) of Co (NO3)2·6H2O were dissolved in 48 mL of deionized water under stirring to obtain a metal salt solution; S2. CTAB was slowly added at a molar ratio of 0.3 to the total amount of metal ions, and finally 3.6 mmol (0.274032 g) of thiourea was slowly added. The resulting mixture was stirred magnetically at 40-60°C for 10 min at a stirring speed of 300-500 rpm; S3. The mixture after stirring in step S2 was transferred to a Teflon-lined stainless steel autoclave, and hydrothermal reaction was carried out at 120°C for 12 h. After cooling to room temperature, the supernatant in the reaction kettle was poured out, and the black precipitate at the bottom of the reaction kettle was left. Finally, the black precipitate was washed by centrifugation with deionized water and ethanol for several times. After washing, vacuum drying was carried out at 60°C for 10 h. After grinding the obtained product in a mortar, the obtained NiCo2S4 existed in mixed sulfide and oxide heterophase.

[0051] Comparative Example 2 S1. 0.4 mmol (0.116316 g) of Ni (NO3)2·6H2O and 0.8 mmol (0.232824 g) of Co (NO3)2·6H2O were dissolved in 48 mL of deionized water under stirring to obtain a metal salt solution; S2. 1 mL of ammonium hydroxide (analytical pure) was added to the above metal salt solution, the pH of the system was 10-11, and a Ni-Co hydroxide suspension was formed. Finally, 3.6 mmol (0.274032 g) of thiourea was slowly added. The resulting mixture was stirred magnetically at 40-60°C for 10 min at a stirring speed of 300-500 rpm; S3. The mixture after stirring in step S2 was transferred to a Teflon-lined stainless steel autoclave, and hydrothermal reaction was carried out at 120°C for 12 h. After cooling to room temperature, the supernatant in the reaction kettle was poured out, and the black precipitate at the bottom of the reaction kettle was left. Finally, the black precipitate was washed by centrifugation with deionized water and ethanol for several times. After washing, vacuum drying was carried out at 60°C for 10 h. After grinding the obtained product in a mortar, the obtained NiCo2S4 existed in random agglomerated particles.

[0052] Comparative Example 3 S1. 0.4 mmol (0.116316 g) of Ni (NO3)2·6H2O and 0.8 mmol (0.232824 g) of Co (NO3)2·6H2O were dissolved in 48 mL of deionized water under stirring to obtain a metal salt solution; S2. Sodium hydroxide with a concentration of 0.5 mol / L was added to the above metal salt solution to make the pH of the system 10-11, then CTAB was slowly added, the molar ratio of CTAB to the total amount of metal ions was 0.3, finally 3.6 mmol (0.274032 g) of thiourea was slowly added, and the obtained mixture was stirred at 40°C for 10 min at a stirring speed of 500 rpm; S3. The stirred mixture of step S2 was transferred to a Teflon-lined stainless steel autoclave, and hydrothermal reaction was carried out at 120°C for 12 h. After cooling to room temperature, the supernatant in the reaction kettle was poured out, and the black precipitate at the bottom of the reaction kettle was left. Finally, the black precipitate was washed by centrifugation with deionized water and ethanol for several times. After washing, vacuum drying was carried out at 60°C for 10 h. After grinding the obtained product in a mortar, the obtained NiCo2S4 existed in the form of Ni / Co hydroxide precipitate, and the particles were coarse.

[0053] Test Example (1) XRD test The working voltage of X-ray diffraction analysis test was 40 KV, the working current was 40 mA, and the test range was 2θ = 20°-80°, and the test results are shown in Figure 1 . Among them, the (220) crystal face corresponds to a 2θ value of 26.8°, the (311) crystal face corresponds to a 2θ value of 31.6°, the (400) crystal face corresponds to a 2θ value of 38.3°, the (511) crystal face corresponds to a 2θ value of 50.5°, and the (440) crystal face corresponds to a 2θ value of 55.3°. It shows that the prepared sample material is NiCo2S4 material, and has a good crystal structure.

[0054] (2) Scanning electron microscope test The scanning electron microscope analysis was tested by using a working voltage of 5 KV to 10 KV, Figure 2 , Figure 3 and Figure 4 are the morphology diagrams of the NiCo2S4 electrode materials prepared in Example 1, Example 2 and Example 3, respectively. The morphology of the materials of Example 1 and Example 2 both presents a three-dimensional embroidered spherical shape, and the material dispersibility of Example 3 decreases due to the addition of too much CTAB, and clusters appear. Figure 5 , Figure 6 and Figure 7 are the morphology diagrams of the NiCo2S4 electrode materials prepared in Comparative Example 1, Comparative Example 2 and Comparative Example 3, respectively, and the morphology is irregular and the particles are coarse.

[0055] (3) Specific surface area test Test method: BET nitrogen adsorption method was used to test the specific surface area, and the sample was treated at 80°C, 10 -3Pa was degassed under vacuum for 6 h, and the adsorption-desorption isotherm was collected in liquid nitrogen environment at 77 K. The BET specific surface area was calculated in the range of P / P0=0.05-0.30.

[0056] The test results are shown in Table 1.

[0057] Table 1

[0058] (4) Electrochemical performance test Preparation of working electrode: the NiCo2S4 electrode material prepared in each example and each comparative example was uniformly mixed with the binder PVDF and the conductive agent acetylene black in a ratio of 8:1:1, wherein the acetylene black was ground, and then an appropriate amount of N-methyl pyrrolidone was added, and the mixture was uniformly mixed in a agate mortar to obtain the required paste-like active electrode material; After the foam nickel was cleaned, pretreated and dried, the paste-like active electrode material was uniformly coated on the foam nickel electrode sheet with a glass rod, and then was placed in a drying oven and dried at 60°C for 24 h. After ensuring that the electrode material on the foam nickel electrode sheet was completely dried, it was taken out and weighed to calculate the mass of the active electrode material on each foam nickel electrode sheet and record the data; In order to prevent the active electrode material coating after drying from being relatively loose and easily falling off and damaged after being soaked in electrolyte, a tablet press was used to press the foam nickel electrode sheet, and the tablet pressing pressure was 3-5 MPa. Then the foam nickel electrode sheet was welded on a nickel strip with a length of about 7 cm to obtain the required working electrode.

[0059] Constant current charge-discharge test was performed on the prepared working electrode with 0~0.4V as the voltage scanning window and 3A / g as the current density. The capacitance data was calculated according to the obtained results, and the electrical performance of the prepared working electrode was analyzed.

[0060] The test results are shown in Table 2.

[0061] Table 2

[0062] Although the present application has been illustrated and described with reference to specific embodiments, it is to be understood that the above-described embodiments are merely illustrative of the present application and are not intended to be limiting thereof. It is understood that various modifications can be made therein by those skilled in the art without departing from the spirit and scope of the present application. It is understood that the technical solutions described in the foregoing embodiments can be modified or some or all of the technical features can be replaced by equivalents without departing from the spirit and scope of the present application. Such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application. Therefore, it is meant that all such modifications and replacements within the scope of the present application are included in the appended claims.

Claims

1. A preparation method of a three-dimensional nano-structured NiCo2S4 electrode material, characterized in that, The method comprises the following steps: S1. Dissolving a cobalt source and a nickel source in deionized water to obtain a metal salt solution; S2. Adding ammonium hydroxide, a surfactant CTAB and an organic sulfur source to the metal salt solution and mixing uniformly; S3. Performing a hydrothermal reaction, and then performing solid-liquid separation, washing and drying to obtain the three-dimensional nano-structured NiCo2S4 electrode material.

2. The method for preparing the three-dimensional nanostructured NiCo2S4 electrode material according to claim 1, characterized in that, In step S1, at least one of the following characteristics is met: (1) The cobalt source comprises at least one of cobalt nitrate hexahydrate, cobalt chloride hexahydrate and cobalt sulfate heptahydrate; (2) The nickel source comprises at least one of nickel nitrate hexahydrate, nickel chloride hexahydrate and nickel sulfate hexahydrate; (3) The cobalt source and the nickel source are measured in a molar ratio of Co and Ni of 1.9-2.1:

1.

3. The method for preparing the three-dimensional nanostructured NiCo2S4 electrode material according to claim 1, characterized in that, In step S2, after adding the ammonium hydroxide, the pH of the system is 10-11.

4. The method of claim 1, wherein the three-dimensional nanostructured NiCo2S4 electrode material is prepared by the steps of: The organic sulfur source comprises thiourea and / or thioacetamide; And / or, the molar ratio of the organic sulfur source to the total amount of nickel and cobalt metal is 2.5-3.5:

1.

5. The method of claim 1, wherein the three-dimensional nanostructured NiCo2S4 electrode material is prepared by the steps of: In step S2, the order of adding the materials is as follows: first, the ammonium hydroxide is added to form a suspension, then the CTAB is added, and finally the organic sulfur source is added.

6. The method of claim 1, wherein the three-dimensional nanostructured NiCo2S4 electrode material is prepared by the steps of: The molar ratio of the CTAB to the total amount of nickel and cobalt metal is 0.2-0.4:

1.

7. The method according to claim 1, wherein the method is characterized by, The temperature of the hydrothermal reaction is 120-180℃, and the time of the hydrothermal reaction is 8-12h.

8. A three-dimensional nanostructured NiCo2S4 electrode material, characterized in that, The three-dimensional nano-structured NiCo2S4 electrode material is prepared by the method according to any one of claims 1-7.

9. A working electrode characterized by, The three-dimensional nano-structured NiCo2S4 electrode material according to claim 8.

10. The working electrode according to claim 9 is used in the preparation of a lithium ion battery, a sodium ion battery or a supercapacitor.

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