A composite material, its preparation and use

Abstract

The application provides a composite material and a preparation method and application thereof, and the preparation method comprises the following steps: grinding and mixing vanadium powder, sulfur powder, selenium powder and carbon nanotubes to obtain first mixed powder; adding a dispersing agent into the first mixed powder and performing dispersion treatment until the dispersing agent is completely volatilized to obtain second mixed powder; performing staged calcination on the second mixed powder to obtain a vanadium sulfoselenide carbon nanotube composite positive electrode material precursor; performing ball milling treatment on the composite positive electrode material precursor, adding a reducing agent to perform stirring and mixing treatment, and then performing filtration and drying to obtain a vanadium sulfoselenide carbon nanotube composite positive electrode material. The vanadium sulfoselenide system coexisting with sulfur and selenium is obtained through the staged calcination mode, and the carbon nanotubes are compounded on the vanadium sulfoselenide through ball milling and a reducing agent to obtain the vanadium sulfoselenide carbon nanotube composite positive electrode material, so that the conductivity and capacity of the composite positive electrode material are further improved.

Description

Technical Field

[0001] This application relates to the field of composite material technology, and in particular to a composite material, its preparation method, and its application. Background Technology

[0002] Currently, the scarcity of lithium-ion batteries, environmental pollution, and low safety have greatly restricted their application in energy storage. Aqueous zinc-ion batteries, on the other hand, have great application prospects due to their advantages such as low cost, environmental friendliness, high safety, and high ionic conductivity.

[0003] Currently, commonly used cathode materials for zinc-ion batteries include manganese oxides, vanadium oxides, and Prussian blue analogues. Among them, vanadium oxides are particularly popular in the field of aqueous zinc-ion batteries due to their abundant resources and the multiple valence states of vanadium. However, vanadium oxides still suffer from some problems such as poor conductivity, easy solubility, and strong electrostatic repulsion, which limit their further development. In contrast, vanadium diselenide (VSe2) materials exhibit ultra-high rate performance in zinc-ion batteries due to their high electronic conductivity, high carrier concentration, and rich redox properties, enabling rapid charge and discharge. However, the rigid VSe2 host material is prone to structural strain during continuous zinc ion insertion / extraction, leading to the dissolution of selenium and loss of Se. 2- The compensation of anions causes a charge imbalance in VSe2, leading to structural collapse. Summary of the Invention

[0004] In view of this, this application provides a composite material, its preparation method, and its application. The preparation method involves mixing and dispersing vanadium powder, sulfur powder, selenium powder, and carbon nanotubes, followed by segmented calcination to obtain a vanadium sulfoselenide carbon nanotube composite cathode material precursor. This precursor is then further dispersed by ball milling and a reducing agent is added to react and obtain a vanadium sulfoselenide carbon nanotube composite cathode material with suitable size and good uniformity. This application obtains a vanadium sulfoselenide system containing both sulfur and selenium through segmented calcination, and then composites carbon nanotubes onto the vanadium sulfoselenide using ball milling and a reducing agent to obtain the vanadium sulfoselenide carbon nanotube composite cathode material, further improving the conductivity and capacity of the composite cathode material.

[0005] The first aspect of this application provides a method for preparing a vanadium sulfide selenide carbon nanotube composite cathode material, comprising the following steps:

[0006] After grinding and mixing vanadium powder, sulfur powder, selenium powder, and carbon nanotubes, a first mixed powder is obtained.

[0007] After adding a dispersant to the first mixed powder, the powder is dispersed until the dispersant completely evaporates to obtain a second mixed powder.

[0008] The second mixed powder was calcined in stages to obtain a precursor for vanadium selenide carbon nanotube composite cathode material.

[0009] After ball milling the composite cathode material precursor, a reducing agent was added and stirred and mixed. The mixture was then filtered and dried to obtain the vanadium sulfide selenide carbon nanotube composite cathode material.

[0010] In this embodiment of the application, the mass of the carbon nanotube is 1%-10% of the total mass of the vanadium powder, the sulfur powder and the selenium powder.

[0011] In this embodiment of the application, the dispersant includes at least one of carbon disulfide, acetone and ethanol, and the reducing agent includes hydrazine solution, sodium borohydride solution or catechol solution.

[0012] In this embodiment of the application, the rotation speed of the dispersion treatment is 600 r / min-2000 r / min, and the treatment time is 30 min-60 min; the ball milling speed of the ball milling treatment is 200 r / min-500 r / min, and the ball milling time is 1 h-12 h.

[0013] In this embodiment of the application, the segmented calcination includes a first calcination treatment, a second calcination treatment, and a third calcination treatment performed sequentially; the heating rate of the first calcination treatment is 2℃ / min-5℃ / min, the holding temperature is 160℃-180℃, and the holding time is 1h-6h; the heating rate of the second calcination treatment is 2℃ / min-5℃ / min, the holding temperature is 220℃-280℃, and the holding time is 1h-6h; the heating rate of the third calcination treatment is 5℃ / min-10℃ / min, the holding temperature is 800℃-1000℃, and the holding time is 1-7 days.

[0014] In this embodiment of the application, the stirring speed of the stirring and mixing process is 400r / min-800r / min, the stirring time is 6h-24h, and the stirring temperature is 60℃-90℃.

[0015] The second aspect of this application provides a vanadium sulfide selenide carbon nanotube composite cathode material prepared by the preparation method provided in the first aspect. The vanadium sulfide selenide carbon nanotube composite cathode material has a two-dimensional layered structure, the lateral dimension of the vanadium sulfide selenide carbon nanotube composite cathode material is 300nm-500nm, and the thickness of the vanadium sulfide selenide carbon nanotube composite cathode material is 50nm-100nm.

[0016] In this embodiment of the application, the specific surface area of ​​the vanadium sulfide selenide carbon nanotube composite cathode material is 30 m². 2 / g-50m 2 / g; The vanadium sulfide selenide carbon nanotube composite cathode material includes a pore structure, which includes micropores, mesopores and macropores.

[0017] A third aspect of this application also provides a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive active layer loaded on the positive current collector, the positive active layer comprising a vanadium sulfide selenide carbon nanotube composite positive electrode material prepared by the preparation method of the first aspect of this application or a vanadium sulfide selenide carbon nanotube composite positive electrode material provided by the second aspect.

[0018] A fourth aspect of this application provides a zinc-ion battery, the zinc-ion battery comprising a positive electrode, a negative electrode, and a separator and an electrolyte located between the positive electrode and the negative electrode; wherein the positive electrode comprises the positive electrode of the third aspect of this application. Attached Figure Description

[0019] Figure 1 A flowchart illustrating a method for preparing a vanadium sulfide selenide carbon nanotube composite cathode material according to an embodiment of this application;

[0020] Figure 2 This is a field emission scanning microscope characterization image of the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 of this application;

[0021] Figure 3 This is a transmission electron microscope (TEM) characterization image of the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 of this application.

[0022] Figure 4 This is a spherical aberration electron microscopy characterization image of the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 of this application;

[0023] Figure 5 This is an X-ray diffraction characterization image of the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 of this application;

[0024] Figure 6 This is the Raman spectrum of the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 of this application;

[0025] Figure 7 This is a nitrogen adsorption-desorption curve of the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 of this application;

[0026] Figure 8 The cyclic voltammetry curves of the vanadium sulfide selenide carbon nanotube composite cathode materials prepared in Example 1 and Comparative Example 1 of this application are shown.

[0027] Figure 9 The graphs show the cycle performance of the vanadium sulfide selenide carbon nanotube composite cathode materials prepared in Example 1 and Comparative Example 1 of this application.

[0028] Figure 10 The AC impedance spectra of the vanadium sulfide selenide carbon nanotube composite cathode materials prepared in Example 1 and Comparative Example 1 of this application are shown. Detailed Implementation

[0029] The present application will be further described in detail below with reference to preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments.

[0030] In this application, all technical terms have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this application.

[0031] Currently, the scarcity of lithium-ion batteries, environmental pollution, and low safety have greatly restricted their application in energy storage. Aqueous zinc-ion batteries, on the other hand, have great application prospects due to their advantages such as low cost, environmental friendliness, high safety, and high ionic conductivity.

[0032] Currently, commonly used cathode materials for zinc-ion batteries include manganese oxides, vanadium oxides, and Prussian blue analogues. Among them, vanadium oxides are particularly popular in the field of aqueous zinc-ion batteries due to their abundant resources and the multiple valence states of vanadium. However, vanadium oxides still suffer from some problems such as poor conductivity, easy solubility, and strong electrostatic repulsion, which limit their further development. In contrast, vanadium diselenide (VSe2) materials exhibit ultra-high rate performance in zinc-ion batteries due to their high electronic conductivity, high carrier concentration, and rich redox properties, enabling rapid charge and discharge. However, the rigid VSe2 host material is prone to structural strain during continuous zinc ion insertion / extraction, leading to the dissolution of selenium and loss of Se. 2- The compensation of anions causes a charge imbalance in VSe2, leading to structural collapse.

[0033] Therefore, anion doping can slow down the breaking of V-Se bonds. Among the many anionic elements, S and Se belong to the same main group and therefore have similar chemical properties. By replacing part of Se with S, the original special layered structure of VSe2 can be maintained. On the other hand, S can adjust the interlayer spacing, improve electronic conductivity and increase defect sites in VSe2, thereby enabling vanadium sulfose selenide to have higher specific capacity and better rate performance.

[0034] To address the aforementioned problems, this application provides a composite material, its preparation method, and its application. The preparation method involves mixing and dispersing vanadium powder, sulfur powder, selenium powder, and carbon nanotubes, followed by segmented calcination to obtain a vanadium sulfoselenide carbon nanotube composite cathode material precursor. This precursor is then further dispersed by ball milling and a reducing agent is added to initiate a reaction, resulting in a vanadium sulfoselenide carbon nanotube composite cathode material of suitable size and good uniformity. This application obtains a vanadium sulfoselenide system containing both sulfur and selenium through segmented calcination, and then composites carbon nanotubes onto the vanadium sulfoselenide using ball milling and a reducing agent, thus obtaining the vanadium sulfoselenide carbon nanotube composite cathode material, further improving the conductivity and capacity of the cathode material.

[0035] This application provides a method for preparing a vanadium sulfide selenide carbon nanotube composite cathode material. Figure 1 The flowchart includes the following steps:

[0036] S101. Vanadium powder, sulfur powder, selenium powder, and carbon nanotubes are ground and mixed to obtain the first mixed powder;

[0037] S102. After adding a dispersant to the first mixed powder, the powder is dispersed until the dispersant is completely volatilized to obtain a second mixed powder.

[0038] S103. The second mixed powder is calcined in stages to obtain a precursor of vanadium selenide carbon nanotube composite cathode material.

[0039] S104. After ball milling the composite cathode material precursor, a reducing agent is added and stirred and mixed. The mixture is then filtered and dried to obtain the vanadium sulfide selenide carbon nanotube composite cathode material.

[0040] In step S101, vanadium powder, sulfur powder, selenium powder, and carbon nanotubes can be commercially available or prepared in-house, depending on actual needs. In some embodiments of this application, the purity of vanadium powder, sulfur powder, and selenium powder is greater than 99.99%. By using high-purity vanadium powder, sulfur powder, and selenium powder as the vanadium source, sulfur source, and selenium source for preparing VSSe, this application effectively avoids the generation of new impurities during the preparation process, thereby obtaining high-purity VSSe. Furthermore, it also facilitates the subsequent removal of impurities by the reducing agent.

[0041] In this embodiment, carbon nanotubes are used as a conductive agent to composite with VSSe. Compared to other carbon conductive agents, carbon nanotubes, as a typical one-dimensional material, have a high specific surface area, excellent hydrogen storage capacity, and excellent electrical conductivity. Carbon nanotubes also possess extremely high tensile strength and elastic modulus, thus exhibiting excellent mechanical properties and structural stability. Composite with VSSe improves the electron transport channels of the composite cathode material while increasing its structural stability. Furthermore, carbon nanotubes exhibit excellent chemical stability, being resistant to acids and alkalis, which can enhance the chemical stability of the composite cathode material.

[0042] In this application, the mass of carbon nanotubes is 1%-10% of the total mass of vanadium powder, sulfur powder, and selenium powder. In some embodiments of this application, the mass of carbon nanotubes can be, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% of the total mass of vanadium powder, sulfur powder, and selenium powder. By controlling the amount of carbon nanotubes added within a suitable range, this application can avoid excessive waste of carbon nanotubes while ensuring that as many carbon nanotubes as possible are composited on VSSe, thereby improving the conductivity of the composite cathode material.

[0043] In this application, the grinding and mixing tool can be, for example, an agate mortar. In some embodiments of this application, the grinding time is 5-30 minutes. In some specific embodiments, the grinding time can be, for example, 5 minutes, 6 minutes, 8 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes. After grinding, a first mixed powder is obtained, the particle size of which is less than or equal to 400 mesh.

[0044] In step S102, the dispersion treatment machine can be, for example, a degassing machine. Dispersing the first mixed powder in the degassing machine can further disperse the first mixed powder, resulting in a mixed powder with uniformly dispersed components. In this embodiment, the dispersant includes at least one of carbon disulfide, acetone, and ethanol. By adding the above-mentioned dispersants, which have low boiling points, they can effectively cooperate with the degassing machine during the dispersion treatment process, uniformly dispersing vanadium powder, sulfur powder, selenium powder, and carbon nanotubes, facilitating the subsequent synthesis of VSSe with uniform components and particle size. Furthermore, the dispersant completely volatilizes during ball milling, without introducing any impurities into the system.

[0045] In this application, the rotational speed for dispersion processing is 600 r / min-2000 r / min, and the processing time is 30 min-60 min. In some embodiments of this application, the rotational speed for dispersion processing can be, for example, 600 r / min, 800 r / min, 1000 r / min, 1200 r / min, 1400 r / min, 1500 r / min, 1600 r / min, 1800 r / min, or 2000 r / min, and the processing time can be, for example, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min. By controlling the dispersion processing parameters within a suitable range, this application ensures that the first mixed powder is uniformly dispersed under the action of the dispersant, and the resulting second mixed powder is a uniformly colored black powder. In some embodiments of this application, the diameter of the grinding balls used in dispersion processing can be, for example, 3 mm.

[0046] In step S103, the obtained second mixed powder is subjected to calcination treatment, which is a segmented calcination treatment. In this embodiment, the segmented calcination includes a first calcination treatment, a second calcination treatment, and a third calcination treatment performed sequentially. In this embodiment, the heating rate of the first calcination treatment is 2℃ / min-5℃ / min, the holding temperature is 160℃-180℃, and the holding time is 1h-6h. In some specific embodiments, the heating rate of the first calcination treatment may be, for example, 2℃ / min, 3℃ / min, 4℃ / min, or 5℃ / min; the holding temperature may be, for example, 160℃, 165℃, 170℃, 175℃, or 180℃; and the holding time may be, for example, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, or 6h. The temperature of the first calcination treatment is 160℃-180℃, and the melting point of sulfur is 112.8℃. In the first calcination treatment stage, sulfur reaches its melting point and is melted first, and then fully mixed with vanadium powder and selenium powder. By controlling the parameters of the first calcination reaction within the above range, the sulfur powder can be fully melted, which is convenient for subsequent compounding with vanadium powder and selenium powder to obtain VSSe.

[0047] In this embodiment, the heating rate of the second calcination treatment is 2℃ / min-5℃ / min, the holding temperature is 220℃-280℃, and the holding time is 1h-6h. In some specific embodiments, the heating rate of the second calcination treatment can be, for example, 2℃ / min, 3℃ / min, 4℃ / min, or 5℃ / min; the holding temperature can be, for example, 220℃, 230℃, 240℃, 250℃, 260℃, 265℃, 270℃, 275℃, or 280℃; and the holding time can be, for example, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, or 6h. The second calcination treatment temperature is 260℃-280℃. The melting point of selenium is 217℃. During the second calcination treatment, selenium reaches its melting point and melts further, mixing thoroughly with vanadium powder and molten sulfur. By controlling the parameters of the second calcination reaction within the above range, the selenium powder can be fully melted and thoroughly mixed and contacted with vanadium powder and molten sulfur, further promoting the occurrence of the composite reaction.

[0048] In this embodiment, the heating rate of the third calcination treatment is 5℃ / min-10℃ / min, the holding temperature is 800℃-1000℃, and the holding time is 1-7 days. In some specific embodiments, the heating rate of the third calcination treatment can be, for example, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, or 10℃ / min; the holding temperature can be, for example, 800℃, 810℃, 820℃, 840℃, 850℃, 860℃, 880℃, 900℃, 920℃, 940℃, 950℃, 960℃, 980℃, or 1000℃; and the holding time can be, for example, 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, or 7 days. By controlling the third calcination treatment within the above ranges, this application allows vanadium powder to react with fully molten and mixed selenium and sulfur to form a composite substance, VSSe. Based on the melting points of sulfur and selenium, this application divides the calcination process into three stages, allowing the sulfur source, selenium source, and vanadium source to react fully. This avoids waste of raw materials and ensures that the composite reaction occurs fully, thereby increasing the yield and improving the purity of the product.

[0049] In this embodiment, the vanadium sulfoselenide carbon nanotube composite cathode material precursor obtained in step S103 is a layered bulk material with a lateral dimension of 10 μm-50 μm and a thickness of 5 μm-30 μm. In some specific embodiments, the lateral dimension of the vanadium sulfoselenide carbon nanotube composite cathode material precursor can be, for example, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm, and the thickness can be, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, or 30 μm. The vanadium sulfoselenide carbon nanotube composite cathode material precursor obtained by calcination has a relatively large size, in the micrometer range, and only a small portion of the carbon nanotubes are composited on the surface of the layered bulk precursor. Therefore, further ball milling and reducing agent treatment are required.

[0050] In step S104, the ball milling speed of the second ball milling process is 200 r / min-500 r / min, and the ball milling time is 1 h-12 h. In some embodiments of this application, the ball milling speed of the second ball milling process can be, for example, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, or 500 r / min, and the ball milling time can be, for example, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, or 12 h. The second ball milling process further disperses the vanadium sulfide selenide carbon nanotube composite cathode material precursor powder, which has a large size and is agglomerated, thus obtaining a uniformly dispersed vanadium sulfide selenide carbon nanotube composite cathode material. This process further reduces the particle size of the obtained vanadium sulfide selenide carbon nanotube composite cathode material, resulting in a composite cathode material with a lateral size of 300nm-500nm and a thickness of 50nm-100nm. This reduces the size of the composite cathode material from the micrometer level to the submicrometer level, increases the specific surface area of ​​the composite cathode material, shortens the diffusion path of ions in the battery, reduces the diffusion coefficient and the internal resistance of the battery, and thus improves the capacity and cycle performance of the zinc-ion battery.

[0051] In this embodiment, after the vanadium sulfide selenide carbon nanotube composite cathode material precursor undergoes a second ball milling process, a reducing agent is added for stirring and mixing. In this embodiment, the reducing agent includes hydrazine solution, sodium borohydride solution, or catechol solution. In some specific embodiments, the mass percentage of the solute in the reducing agent is 20%-80%. By adding hydrazine solution, sodium borohydride solution, or catechol solution as a reducing agent, this application achieves two benefits: First, the reducing agent promotes the composite formation of carbon nanotubes and VSSe, causing them to disperse and adhere to the surface or interior of VSSe. The carbon nanotubes interweave and surround VSSe to form a porous network structure, providing a connected conductive network for electron conduction, further improving the conductivity of the composite cathode material. Second, the reducing agent can also react with excess sulfur and selenium powder, removing unreacted raw material impurities and further improving the purity of the composite cathode material.

[0052] In this embodiment, the stirring speed of the mixing process is 400 r / min-800 r / min, the stirring time is 6 h-24 h, and the stirring temperature is 60 °C-90 °C. In some embodiments of this application, the stirring speed can be, for example, 400 r / min, 450 r / min, 500 r / min, 550 r / min, 600 r / min, 650 r / min, 700 r / min, 750 r / min, or 800 r / min; the stirring time can be, for example, 6 h, 8 h, 10 h, 12 h, 14 h, 15 h, 16 h, 18 h, 20 h, 22 h, or 24 h; and the stirring temperature can be, for example, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, or 90 °C. By controlling the parameters of the mixing process within the above ranges, this application can further promote the reduction of the hydrazine solution.

[0053] The preparation method provided in this application uses readily available raw materials, has a simple preparation process, and introduces no impurities. The resulting vanadium sulfide selenide carbon nanotube composite cathode material has uniform size, good dispersibility, and excellent conductivity and stability.

[0054] This application also provides a vanadium sulfide selenide carbon nanotube composite cathode material prepared by the preparation method described above. In this embodiment, the vanadium sulfide selenide carbon nanotube composite cathode material is a two-dimensional layered material with a lateral dimension of 300nm-500nm and a thickness of 50nm-100nm. In some specific embodiments, the lateral dimension of the vanadium sulfide selenide carbon nanotube composite cathode material can be, for example, 300nm, 350nm, 400nm, 450nm, or 500nm, and the thickness can be, for example, 50nm, 60nm, 70nm, 80nm, 90nm, or 100nm. The size of the vanadium sulfide selenide carbon nanotube composite cathode material obtained after the second ball milling treatment is significantly reduced, from the micrometer level to the submicrometer level. This is because the second ball milling treatment greatly disperses the bulk precursor of the composite cathode material obtained after calcination, effectively solving the problems of agglomeration and size inhomogeneity of the composite cathode material.

[0055] In this embodiment, the carbon nanotube composite cathode material of vanadium sulfide selenide (VSSe) can have carbon nanotubes attached to the surface of layered VSSe or distributed within the internal pores of VSSe. Carbon nanotubes can significantly improve the conductivity of the composite cathode material and further enhance its structural stability. Moreover, compared to other carbon conductive materials, carbon nanotubes have a larger specific surface area and excellent hydrogen storage capacity. Compositeting them into VSSe can significantly improve the conductivity and stability of the composite cathode material, thereby enhancing the electrochemical performance of zinc-ion batteries.

[0056] In this embodiment, the specific surface area of ​​the vanadium sulfide selenide carbon nanotube composite cathode material is 30 m². 2 / g-50m 2 / g. In some specific embodiments, the specific surface area of ​​the vanadium sulfide selenide carbon nanotube composite cathode material can be, for example, 30 m². 2 / g、35m 2 / g、40m 2 / g、45m 2 / g, 50m 2 / g. This application further enhances the specific surface area of ​​the composite cathode material through composite carbon nanotubes, thereby further improving the capacity of the zinc-ion battery. In the embodiments of this application, the vanadium sulfide selenide carbon nanotube composite cathode material includes a pore structure, which includes micropores, mesopores, and macropores. Among them, the pore structure with a pore size less than or equal to 2 nm is a micropore, the pore structure with a pore size greater than 2 nm and less than 50 nm is a mesopore, and the pore structure with a pore size greater than or equal to 50 nm is a macropore. In some embodiments of this application, the pore size of the vanadium sulfide selenide carbon nanotube composite cathode material is mostly concentrated in three regions: 2 nm-3 nm, 10 nm-18 nm, and 45 nm-55 nm.

[0057] This application also provides a positive electrode sheet, which includes a positive current collector and a positive active layer loaded on the positive current collector. The positive active layer includes a vanadium sulfide selenide carbon nanotube composite positive electrode material prepared by the preparation method provided above, or the vanadium sulfide selenide carbon nanotube composite positive electrode material provided above. In the embodiments of this application, the positive current collector is a commonly used positive current collector in the art, including but not limited to titanium foil and stainless steel foil.

[0058] In some embodiments of this application, the positive electrode active layer further includes a conductive agent and a binder. In these embodiments, the conductive agent can be any conductive agent known in the art. In some embodiments, the conductive agent can be one or more of acetylene black, super carbon black, graphene, and carbon nanotubes. In these embodiments, the binder can be any binder known in the art. In some embodiments, the binder can be one or more of polyvinylidene fluoride and styrene-butadiene rubber.

[0059] This application also provides a zinc-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte located between the positive and negative electrodes. The positive electrode includes the positive electrode described above. In embodiments of this application, the zinc-ion battery is, for example, an aqueous zinc-ion battery. In some embodiments of this application, the zinc-ion battery may be, for example, a primary zinc-ion battery or a secondary zinc-ion battery. In embodiments of this application, the separator includes, but is not limited to, a glass fiber film or a polymer film. In embodiments of this application, the electrolyte may be any electrolyte known in the art for zinc-ion batteries.

[0060] The present application will be further described below with reference to several embodiments:

[0061] Example 1

[0062] Mix 0.5094g of vanadium powder, 0.32g of sulfur powder, and 0.7896g of selenium powder, then add 0.081g of carbon nanotubes and pour the mixture into an agate mortar. Grind for 30 minutes, then transfer the resulting first mixed powder to a degassing machine box. Add 5mL of carbon disulfide solution and 3mm grinding beads, and disperse at 2000r / min for 60 minutes until the carbon disulfide is completely volatilized. Transfer the resulting second mixed powder to a quartz tube and seal it using a vacuum sealing machine to make the powder filling more compact. Then transfer it to a tube furnace for calcination, initially at 2℃ / The temperature was increased from room temperature to 160℃ at a rate of 2℃ / min and held for 3 hours; then increased from 160℃ to 260℃ at a rate of 2℃ / min and held for 3 hours; finally increased from 260℃ to 1000℃ at a rate of 5℃ / min and held for 3 days, and then cooled to room temperature to obtain the precursor of vanadium sulfide selenide carbon nanotube composite cathode material; the precursor of vanadium sulfide selenide carbon nanotube composite cathode material was ball-milled at 400 r / min for 12 hours, then stirred at 80℃ for 12 hours with a 50% hydrazine solution, and finally filtered and dried to obtain the vanadium sulfide selenide carbon nanotube composite cathode material.

[0063] The vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 was characterized by field emission scanning microscopy, and the results are as follows: Figure 2 As shown, from Figure 2 As can be seen, after the second ball milling process, the size of the composite cathode material is significantly reduced, and after treatment with hydrazine solution, carbon nanotubes form a network structure in VSSe, which is uniformly interwoven and dispersed around VSSe.

[0064] The vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 was characterized by transmission electron microscopy, and the results were obtained. Figure 3 It can be seen that the vanadium sulfide selenide carbon nanotube composite cathode material exhibits a distinct two-dimensional layered stacked structure with carbon nanotubes interleaved on the VSSe surface. Figure 3 The lattice fringes of VSSe are distinct, with a measured lattice fringe spacing of 0.2698 nm, corresponding to the (100) crystal plane of VSSe. Furthermore, Figure 4 and Figure 5 The results of aberration-corrected electron microscopy and X-ray diffraction characterization of the vanadium sulfide selenide carbon nanotube composite cathode material show that VSSe was successfully prepared without any excess impurities.

[0065] Figure 6 The image shows the Raman spectrum of the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1. It can be seen that the spectrum at 140.2 cm⁻¹ is obtained. -1 and 236.3cm -1 The VSSe characteristic peak at 1346 cm⁻¹ and the peak at 1346 cm⁻¹ -1 and 1582cm-1 The carbon characteristic peaks corresponding to the carbon nanotubes at that location.

[0066] Figure 7 The figure shows the nitrogen adsorption-desorption curve of the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1. As can be seen from the figure, the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 of this application has a porous structure, including micropores, mesopores and macropores, and the pore size is concentrated in three regions: 2nm-3nm, 10nm-18nm, and 45nm-55nm.

[0067] Example 2

[0068] Mix 0.5094g of vanadium powder, 0.32g of sulfur powder, and 0.7896g of selenium powder, then add 0.0162g of carbon nanotubes and pour the mixture into an agate mortar. Grind for 30 minutes, then transfer the resulting first mixed powder to a degassing machine box. Add 5mL of carbon disulfide solution and 3mm grinding beads, and disperse at 2000r / min for 60 minutes until the carbon disulfide is completely volatilized. Transfer the resulting second mixed powder to a quartz tube and seal it using a vacuum sealing machine to make the powder filling more compact. Then transfer it to a tube furnace for calcination, initially at 2℃. The temperature was increased from room temperature to 160℃ at a rate of 2℃ / min and held for 3 hours; then increased from 160℃ to 260℃ at a rate of 2℃ / min and held for 3 hours; finally increased from 260℃ to 1000℃ at a rate of 5℃ / min and held for 3 days, and then cooled to room temperature to obtain the precursor of vanadium sulfide selenide carbon nanotube composite cathode material; the precursor of vanadium sulfide selenide carbon nanotube composite cathode material was ball-milled at 400 r / min for 12 hours, then stirred at 80℃ for 12 hours with a 50% hydrazine solution, and finally filtered and dried to obtain the vanadium sulfide selenide carbon nanotube composite cathode material.

[0069] Example 3

[0070] Mix 0.5094g of vanadium powder, 0.32g of sulfur powder, and 0.7896g of selenium powder, then add 0.162g of carbon nanotubes and pour the mixture into an agate mortar. Grind for 30 minutes, then transfer the resulting first mixed powder to a degassing machine box. Add 5mL of carbon disulfide solution and 3mm grinding beads, and disperse at 2000r / min for 60 minutes until the carbon disulfide is completely volatilized. Transfer the resulting second mixed powder to a quartz tube and seal it using a vacuum sealing machine to make the powder filling more compact. Then transfer it to a tube furnace for calcination, initially at 2℃ / The temperature was increased from room temperature to 160℃ at a rate of 2℃ / min and held for 3 hours; then increased from 160℃ to 260℃ at a rate of 2℃ / min and held for 3 hours; finally increased from 260℃ to 1000℃ at a rate of 5℃ / min and held for 3 days, and then cooled to room temperature to obtain the precursor of vanadium sulfide selenide carbon nanotube composite cathode material; the precursor of vanadium sulfide selenide carbon nanotube composite cathode material was ball-milled at 400 r / min for 12 hours, then stirred at 80℃ for 12 hours with a 50% hydrazine solution, and finally filtered and dried to obtain the vanadium sulfide selenide carbon nanotube composite cathode material.

[0071] Example 4

[0072] Mix 0.5094g of vanadium powder, 0.32g of sulfur powder, and 0.7896g of selenium powder, then add 0.081g of carbon nanotubes and pour the mixture into an agate mortar. Grind for 30 minutes, then transfer the resulting first mixed powder to a degassing machine box. Add 5mL of carbon disulfide solution and 3mm grinding beads, and disperse at 2000r / min for 60 minutes until the carbon disulfide is completely volatilized. Transfer the resulting second mixed powder to a quartz tube and seal it using a vacuum sealing machine to make the powder filling more compact. Then transfer it to a tube furnace for calcination, initially at 2℃ / The temperature was increased from room temperature to 160℃ at a rate of 2℃ / min and held for 3 hours; then increased from 160℃ to 260℃ at a rate of 2℃ / min and held for 3 hours; finally increased from 260℃ to 1000℃ at a rate of 5℃ / min and held for 7 days, and then cooled to room temperature to obtain the precursor of vanadium sulfide selenide carbon nanotube composite cathode material; the precursor of vanadium sulfide selenide carbon nanotube composite cathode material was ball-milled at 400 r / min for 12 hours, then stirred at 80℃ for 12 hours with a 50% hydrazine solution, and finally filtered and dried to obtain the vanadium sulfide selenide carbon nanotube composite cathode material.

[0073] Example 5

[0074] Mix 0.5094g of vanadium powder, 0.32g of sulfur powder, and 0.7896g of selenium powder, then add 0.081g of carbon nanotubes and pour the mixture into an agate mortar. Grind for 30 minutes, then transfer the resulting first mixed powder to a degassing machine box. Add 5mL of carbon disulfide solution and 3mm grinding beads, and disperse at 2000r / min for 60 minutes until the carbon disulfide is completely volatilized. Transfer the resulting second mixed powder to a quartz tube and seal it using a vacuum sealing machine to make the powder filling more compact. Then transfer it to a tube furnace for calcination, initially at 2℃. The temperature was increased from room temperature to 160℃ at a rate of 2℃ / min and held for 3 hours; then increased from 160℃ to 260℃ at a rate of 2℃ / min and held for 3 hours; finally increased from 260℃ to 1000℃ at a rate of 5℃ / min and held for 3 days, and then cooled to room temperature to obtain the precursor of vanadium sulfide selenide carbon nanotube composite cathode material; the precursor of vanadium sulfide selenide carbon nanotube composite cathode material was ball-milled at 400 r / min for 1 hour, then stirred at 80℃ for 12 hours with a 50% hydrazine solution, and finally filtered and dried to obtain vanadium sulfide selenide carbon nanotube composite cathode material.

[0075] Example 6

[0076] Mix 0.5094g of vanadium powder, 0.32g of sulfur powder, and 0.7896g of selenium powder, then add 0.081g of carbon nanotubes and pour the mixture into an agate mortar. Grind for 30 minutes, then transfer the resulting first mixed powder to a degassing machine box. Add 5mL of carbon disulfide solution and 3mm grinding beads, and disperse at 2000r / min for 60 minutes until the carbon disulfide is completely volatilized. Transfer the resulting second mixed powder to a quartz tube and seal it using a vacuum sealing machine to make the powder filling more compact. Then transfer it to a tube furnace for calcination, initially at 2℃ / The temperature was increased from room temperature to 160℃ at a rate of 2℃ / min and held for 3 hours; then increased from 160℃ to 260℃ at a rate of 2℃ / min and held for 3 hours; finally increased from 260℃ to 1000℃ at a rate of 5℃ / min and held for 3 days, and then cooled to room temperature to obtain the precursor of vanadium sulfide selenide carbon nanotube composite cathode material; the precursor of vanadium sulfide selenide carbon nanotube composite cathode material was ball-milled at 400 r / min for 12 hours, then stirred at 80℃ for 12 hours with hydrazine solution of 80% by mass, and finally filtered and dried to obtain vanadium sulfide selenide carbon nanotube composite cathode material.

[0077] Comparative Example 1

[0078] Mix 0.5094g of vanadium powder, 0.32g of sulfur powder, and 1.5792g of selenium powder, then add 0.081g of carbon nanotubes and pour the mixture into an agate mortar. Grind for 30 minutes, then transfer the resulting first mixed powder to a degassing machine box. Add 5mL of carbon disulfide solution and 3mm grinding beads, and disperse at 2000r / min for 60 minutes until the carbon disulfide is completely volatilized. Transfer the resulting second mixed powder to a quartz tube and seal it using a vacuum tube sealing machine. The powder was sealed to make it more compact, and then transferred to a tube furnace for calcination. The temperature was increased from room temperature to 1000℃ at a rate of 5℃ / min, held for 3 days, and then cooled to room temperature to obtain the precursor of vanadium sulfose selenide carbon nanotube composite cathode material. The precursor of vanadium sulfose selenide carbon nanotube composite cathode material was ball-milled at 400 r / min for 12 h, and then stirred at 80℃ for 12 h with a 50% hydrazine solution. Finally, it was filtered and dried to obtain vanadium sulfose selenide carbon nanotube composite cathode material.

[0079] The vanadium sulfide carbon nanotube composite cathode material prepared in Example 1 and Comparative Example 1, along with acetylene black and polyvinylidene fluoride, were added to N-methyl-2-pyrrolidone solvent at a mass ratio of 7:2:1. The mixture was stirred to obtain a cathode active slurry. The obtained cathode active slurry was coated onto a titanium foil current collector and vacuum dried at 80°C for 12 hours to obtain a cathode electrode. A zinc foil with a thickness of 100 μm was selected as the cathode electrode, GF / D glass fiber was used as the separator, and a 2 mol / L trifluoromethane zinc sulfate solution was used as the electrolyte to assemble a button cell.

[0080] Cyclic voltammetry (CV) was tested at scan rates of 0.1 mV / s to 100 mV / s on an electrochemical station; constant current charge-discharge tests ranging from 0.1 V to 1.7 V were performed on a blue-electric test system, and the results are as follows. Figure 8 and Figure 9 As shown; then, an AC impedance test was performed on the battery, with a frequency range of 0.01Hz-1000000Hz and an amplitude of 10mV. The measured results are as follows. Figure 10 As shown.

[0081] from Figure 8 As can be seen, compared with the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 without segmented calcination, the battery prepared by the vanadium sulfide selenide carbon nanotube composite cathode material obtained by segmented calcination in Example 1 of this application shows two pairs of redox peaks and the curves of four scans highly overlap, indicating that the cathode prepared by this composite cathode material is highly reversible in the zinc ion insertion / extraction process and has excellent electrochemical performance.

[0082] contrast Figure 9The cycling performance of Example 1 and Comparative Example 1 shows that, compared with the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Example 1 without segmented calcination, the battery prepared by the vanadium sulfide selenide carbon nanotube composite cathode material obtained by segmented calcination in Example 1 of this application maintains a high capacity at different current densities and can still maintain a high specific capacity after 900 cycles. The cathode is highly reversible in the zinc ion insertion / extraction process, indicating that the segmented calcination method can effectively improve the cycling performance of the cathode material.

[0083] Figure 10 The AC impedance spectra of the vanadium sulfide selenide carbon nanotube composite cathode materials prepared in Example 1 and Comparative Example 1 are shown. It can be seen that the charge transfer impedance of the vanadium sulfide selenide carbon nanotube composite cathode material in Example 1 is only 12Ω, while the charge transfer impedance of the vanadium sulfide selenide carbon nanotube composite cathode material prepared in Comparative Example 1 is as high as 70Ω. This indicates that the composite cathode material prepared by segmented calcination has less resistance to charge transport and is more conducive to ion diffusion and electron transfer.

[0084] The preferred embodiments have been described in detail above, but the present invention is not limited to the specific implementation methods described above. Those skilled in the art can make various specific modifications under the guidance of this application without departing from the scope of protection of this application, and these modifications all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a vanadium sulfide selenide carbon nanotube composite cathode material, characterized in that, Includes the following steps: After grinding and mixing vanadium powder, sulfur powder, selenium powder, and carbon nanotubes, a first mixed powder is obtained. A dispersant is added to the first mixed powder and then dispersed until the dispersant is completely volatilized to obtain a second mixed powder; the dispersant includes at least one of carbon disulfide, acetone and ethanol. The second mixed powder is subjected to segmented calcination to obtain a vanadium sulfide selenide carbon nanotube composite cathode material precursor. The segmented calcination includes a first calcination treatment, a second calcination treatment, and a third calcination treatment performed sequentially. The heating rate of the first calcination treatment is 2℃ / min-5℃ / min, the holding temperature is 160℃-180℃, and the holding time is 1 h-6 h. The heating rate of the second calcination treatment is 2℃ / min-5℃ / min, the holding temperature is 220℃-280℃, and the holding time is 1 h-6 h. The heating rate of the third calcination treatment is 5℃ / min-10℃ / min, the holding temperature is 800℃-1000℃, and the holding time is 1-7 days. The composite cathode material precursor is ball-milled, then a reducing agent is added and stirred and mixed. After filtration and drying, vanadium sulfide selenide carbon nanotube composite cathode material is obtained. The reducing agent includes hydrazine solution, sodium borohydride solution or catechol solution.

2. The preparation method of the vanadium sulfide selenide carbon nanotube composite cathode material as described in claim 1, characterized in that, The mass of the carbon nanotubes is 1%-10% of the total mass of the vanadium powder, the sulfur powder, and the selenium powder.

3. The preparation method of the vanadium sulfide selenide carbon nanotube composite cathode material as described in claim 1, characterized in that, The rotational speed for the dispersion treatment is 600 r / min-2000 r / min, and the treatment time is 30 min-60 min; the ball milling speed for the ball milling treatment is 200 r / min-500 r / min, and the ball milling time is 1 h-12 h.

4. The method for preparing the vanadium sulfide selenide carbon nanotube composite cathode material according to any one of claims 1-3, characterized in that, The stirring speed for the mixing process is 400 r / min-800 r / min, the stirring time is 6 h-24 h, and the stirring temperature is 60℃-90℃.

5. A vanadium sulfide selenide carbon nanotube composite cathode material prepared by the preparation method according to any one of claims 1-4, characterized in that, The vanadium sulfide selenide carbon nanotube composite cathode material has a two-dimensional layered structure, with a lateral dimension of 300 nm-500 nm and a thickness of 50 nm-100 nm.

6. The vanadium sulfide selenide carbon nanotube composite cathode material as described in claim 5, characterized in that, The specific surface area of ​​the vanadium sulfide selenide carbon nanotube composite cathode material is 30 m². 2 / g-50 m 2 / g; The vanadium sulfide selenide carbon nanotube composite cathode material includes a pore structure, which includes micropores, mesopores and macropores.

7. A positive electrode sheet, characterized in that, The positive electrode includes a positive current collector and a positive active layer loaded on the positive current collector. The positive active layer includes a vanadium sulfide selenide carbon nanotube composite positive electrode material prepared by the preparation method according to any one of claims 1-4 or the vanadium sulfide selenide carbon nanotube composite positive electrode material according to claim 5 or 6.

8. A zinc-ion battery, characterized in that, The zinc-ion battery includes a positive electrode, a negative electrode, a separator, and an electrolyte located between the positive electrode and the negative electrode; wherein the positive electrode includes the positive electrode as described in claim 7.

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