Preparation of ni-nis2 heterostructure porous carbon gel, product and application thereof

Abstract

The application discloses a kind of Ni-NiS2 Heterostructure @ Porous Carbon Gel Preparation and its product and application.The present application prepares porous hydrogel by polyvinyl alcohol and graphene oxide, and Ni-NiS2 Heterostructure is grown in situ on the gel base material.The Ni-NiS2 Heterostructure prepared by this method is nanoparticle, has more adsorption and catalytic site, NiS2 shows more excellent adsorption capacity, Ni shows stronger catalytic capacity, and the construction of heterojunction surface controls the interface electronic effect and improves the intrinsic electronic conductivity of material.The built-in electric field formed by heterojunction surface helps the polysulfide near it to get ions quickly, and weakens the shuttle effect of polysulfide.Porous carbon gel framework has larger specific surface area, which helps to alleviate the volume change problem of lithium-sulfur battery.The composite material effectively improves the polysulfide shuttle problem and speeds up the reaction kinetics of electrode.

Description

Technical Field

[0001] This invention belongs to the field of lithium-sulfur battery technology, and particularly relates to the preparation of a Ni-NiS2 heterostructure@porous carbon gel, its products and applications. Background Technology

[0002] Lithium-sulfur batteries are known for their high theoretical specific capacity (1675 mAh g). -1 High specific energy density (2500Wh / kg) -1 Sulfur, with its abundant reserves and low price, is expected to become one of the next-generation energy storage devices. However, several key issues restrict its large-scale application. First, the electronic and ionic insulation of sulfur species: S and Li₂S have extremely low conductivity, which hinders the efficient transfer of electrons and ions and their participation in reactions. Second, the shuttle effect of polysulfides: during discharge, soluble long-chain polysulfides generated will shuttle back and forth between the positive and negative electrodes under the influence of electric field strength and concentration gradient, leading to a significant loss of sulfur active material. Finally, there is the issue of volume change before and after charge and discharge: sulfur undergoes a huge density change before and after lithiation, resulting in a nearly 76% volume change of the active material.

[0003] To address the aforementioned issues, researchers first introduced carbon materials, which possess high conductivity and diverse morphologies, as sulfur hosts. However, carbon materials exhibit weak physical adsorption, thus transition metal compounds (MoS2, Co9S8, FeS2, etc.) with strong adsorption and catalytic capabilities have been extensively studied. Due to their unique physical morphology and surface properties, some transition metal compounds exhibit excellent chemisorption capabilities for polysulfides, while others demonstrate strong catalytic capabilities, accelerating the redox reaction kinetics of lithium-sulfur batteries. Given the significant importance of designing and developing multifunctional sulfur hosts, this invention uniformly disperses heterostructures with adsorption and catalytic capabilities within porous carbon gels, preparing a unique three-dimensional conductive network doped with functional particles. Summary of the Invention

[0004] This invention provides a method for preparing Ni-NiS2 heterostructure@porous carbon gel, its products and applications. By designing a lithium-sulfur battery sulfur fixation material with high conductivity, strong adsorption capacity for polysulfides and catalytic ability, high capacity and long life of lithium-sulfur batteries can be achieved.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing Ni-NiS2 heterostructure@porous carbon gel includes the following steps:

[0007] (1) Polyvinyl alcohol, nickel chloride and deionized water were mixed and heated in a water bath to obtain a hydrogel containing nickel chloride.

[0008] (2) Add graphene oxide to the hydrogel obtained in step (1) and stir at room temperature to obtain a hydrogel-graphene oxide mixture;

[0009] (3) Sodium sulfide is dissolved in deionized water to obtain a sodium sulfide solution, which is then added to the hydrogel-graphene oxide mixture obtained in step (2), stirred, and freeze-dried to obtain the precursor material;

[0010] (4) Under an argon atmosphere, the precursor material was heat-treated at 700-900℃ for 2h to obtain Ni-NiS2 heterostructure@porous carbon gel.

[0011] Further, in step (1), the mass ratio of polyvinyl alcohol to nickel chloride is 1:0.04.

[0012] Furthermore, the mass ratio of sodium sulfide to nickel chloride added is 1-4:0.4.

[0013] Further, in step (1), the water bath heating is performed at 40°C for 1-4 hours.

[0014] The present invention also provides a Ni-NiS2 heterostructure@porous carbon gel prepared by the aforementioned method.

[0015] The present invention also provides an application of the aforementioned Ni-NiS2 heterostructure@porous carbon gel in lithium-sulfur battery cathode materials.

[0016] Furthermore, the preparation method of the lithium-sulfur battery cathode material is as follows: Ni-NiS2 heterostructure@porous carbon gel and sublimed sulfur powder are mixed in a mass ratio of 3:7-1:9 and heated in an argon atmosphere at 155°C for 12 hours to obtain sulfur / Ni-NiS2 heterostructure@porous carbon gel cathode material.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects:

[0018] 1. This invention prepares a porous hydrogel using polyvinyl alcohol and graphene oxide, and simultaneously grows a Ni-NiS2 heterostructure in situ on the gel substrate. The preparation process is short and simple. The Ni-NiS2 heterostructure@porous carbon gel obtained after heat treatment has a high specific surface area and possesses dual-functional active centers for adsorption and catalysis. This effectively mitigates the shuttle effect of polysulfides, improves the utilization rate of sulfur-containing active materials, and enhances the cycle life of lithium-sulfur batteries.

[0019] 2. The prepared sulfur / Ni-NiS2 heterostructure@porous carbon gel cathode material, under a current density of 0.1C (1C = 1675 mAh g / g), -1 It has a first-cycle discharge specific capacity of 1545mAhg. -1 High specific capacity; after 100 cycles, the specific capacity remains at 807 mAh g. -1 It exhibited excellent cycle stability.

[0020] 3. This invention is an excellent sulfur-fixing material of Ni-NiS2 heterostructure@porous carbon gel with high conductivity, strong adsorption capacity and catalytic ability. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 This is a scanning electron microscope image of the Ni-NiS2 heterostructure@porous carbon gel prepared in Example 5;

[0023] Figure 2 X-ray diffraction pattern of the Ni-NiS2 heterostructure@porous carbon gel prepared in Example 5;

[0024] Figure 3 The image shows a long-cycle diagram of the sulfur / Ni-NiS2 heterostructure@porous carbon gel prepared in Example 5 after 100 cycles at 0.1C.

[0025] Figure 4 The magnification diagram of the sulfur / Ni-NiS2@porous carbon gel prepared in Example 5 at different magnification rates. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0032] All raw materials used in the following embodiments of the present invention were obtained from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0033] Unless otherwise specified, the term "parts" in this invention refers to "parts by weight".

[0034] This invention designs a lithium-sulfur battery sulfur fixation material with high conductivity, strong adsorption capacity for polysulfides, and catalytic activity, aiming to achieve high capacity and long lifespan in lithium-sulfur batteries. To achieve the above objectives, this invention provides a porous carbon gel lithium-sulfur battery sulfur fixation material based on a Ni-NiS2 heterostructure, its preparation method, and its applications. The Ni-NiS2 heterostructure prepared by this method is in the form of nanoparticles with more adsorption and catalytic sites. NiS2 exhibits superior adsorption capacity, and Ni demonstrates stronger catalytic activity. Simultaneously, the construction of the heterojunction interface regulates the electronic effects at the interface and improves the intrinsic electronic conductivity of the material. Furthermore, the built-in electric field formed at the heterojunction surface helps polysulfides in its vicinity to acquire ions quickly, reducing the shuttle effect of polysulfides. The resulting porous carbon gel framework has a large specific surface area, which helps alleviate the volume change problem in lithium-sulfur batteries. The specific scheme is as follows:

[0035] A method for preparing Ni-NiS2 heterostructure@porous carbon gel includes the following steps:

[0036] (1) Add 1g of polyvinyl alcohol to a 10-30mL weighing bottle, then add 0.04g of nickel chloride to a 5-10mL beaker containing deionized water, and then add it to the weighing bottle. Heat in a 40℃ water bath for 1-4h to obtain a hydrogel containing nickel chloride. In some preferred embodiments, the amount of deionized water is 5-10mL. In a more preferred embodiment, it is 5mL. The reason is that if the deion content is too high, the pore size of the hydrogel will be too large after high-temperature carbonization, which is not conducive to the sealing of sulfur active substances. If the deion content is too low, the pore size will be too small and the sulfur active substances will not be able to effectively penetrate into the pores.

[0037] (2) Add 10-20 mL of graphene oxide with a concentration of 10 mg / mL to the hydrogel obtained in step (1) and stir at room temperature for 12 h to obtain a hydrogel-graphene oxide mixture.

[0038] (3) Dissolve 0.1-0.4g of sodium sulfide in a beaker containing 5-10mL of deionized water. After it is completely dissolved, add it to the hydrogel-graphene oxide mixture obtained in step (2). Stir for 4-10h and then place it in a freeze dryer to dry overnight to obtain the precursor material. In some preferred embodiments, the amount of deionized water used is 5-10mL.

[0039] (4) Place the precursor material from step (3) in a crucible and heat-treat it in a tube furnace at 700-900℃ for 2 hours (preferably 700℃) with argon atmosphere to finally obtain a multifunctional sulfur-fixing material with Ni-NiS2 heterostructure@porous carbon gel.

[0040] In some preferred embodiments, the mass ratio of polyvinyl alcohol to sodium sulfide is 1:(0.1-0.4). In other preferred embodiments, it is 1:0.1, 1:0.2, 1:0.3, or 1:0.4. The content of sodium sulfide affects product performance because different amounts influence the amount of NiS2 generated. The volume ratio of polyvinyl alcohol to graphene oxide solution is 1 g:(10-20) mL, and in some preferred embodiments, it is 1 g:10 mL.

[0041] The present invention also provides a Ni-NiS2 heterostructure@porous carbon gel prepared by the aforementioned method.

[0042] This invention also provides an application of the aforementioned Ni-NiS2 heterostructure@porous carbon gel in lithium-sulfur battery cathode materials. The preparation method of the lithium-sulfur battery cathode material is as follows: Ni-NiS2 heterostructure@porous carbon gel and sublimed sulfur powder are mixed at a mass ratio of 3:7-1:9 (in some preferred embodiments, 3:7 and 2:8, more preferably 3:7), and heated at 155°C for 12 hours to obtain a sulfur / Ni-NiS2 heterostructure@porous carbon gel cathode material.

[0043] The following embodiments are further illustrations of the technical solution of the present invention.

[0044] Example 1

[0045] (1) Add 1g of polyvinyl alcohol to a 20mL weighing bottle, then add 0.04g of nickel chloride to 5mL of deionized water, and then add it to the weighing bottle to mix with polyvinyl alcohol. Heat in a 40℃ water bath for 2h to obtain a hydrogel containing nickel chloride.

[0046] (2) Add 10 mL of graphene oxide solution with a concentration of 10 mg / mL to the hydrogel obtained in step (1) and stir at room temperature for 12 h to obtain a hydrogel-graphene oxide mixture.

[0047] (3) The hydrogel-graphene oxide mixture from step (2) was placed in a crucible and heat-treated at 700°C for 2 hours in a tube furnace with argon atmosphere to finally obtain a multifunctional sulfur-fixing material of Ni@porous carbon gel.

[0048] (4) The Ni@porous carbon gel and sublimed sulfur powder are thoroughly ground and mixed, and then mixed in a mass ratio of 3:7. The mixture is heated at 155°C for 12 hours to obtain sulfur / Ni@porous carbon gel cathode material.

[0049] The sulfur / Ni@porous carbon gel prepared using this embodiment exhibits a first-cycle discharge specific capacity of 1042 mAh g⁻¹ at a current density of 0.1 C. -1 It still maintains 450mAh after 100 cycles. -1 Specific capacity.

[0050] Example 2

[0051] (1) Add 1g of polyvinyl alcohol to a 20mL weighing bottle, then add 0.04g of nickel chloride to 5mL of deionized water, and then add it to the weighing bottle to mix with polyvinyl alcohol. Heat in a 40℃ water bath for 2h to obtain a hydrogel containing nickel chloride.

[0052] (2) Add 10 mL of graphene oxide solution with a concentration of 10 mg / mL to the hydrogel obtained in step (1) and stir at room temperature for 12 h to obtain a hydrogel-graphene oxide mixture.

[0053] (3) Dissolve 0.2g sodium sulfide in 5mL of deionized water. After it is completely dissolved, add it to the hydrogel-graphene oxide mixture obtained in step (2). Stir for 4 hours and then place it in a freeze dryer to dry overnight to obtain the precursor material.

[0054] (3) Place the precursor material from step (2) in a crucible and heat-treat it at 700°C for 2 hours in a tube furnace with argon atmosphere to finally obtain a multifunctional sulfur-fixing material with Ni-NiS2 heterostructure@porous carbon gel.

[0055] (4) The Ni-NiS2 heterostructure@porous carbon gel and sublimed sulfur powder were thoroughly ground and mixed. They were mixed in a mass ratio of 3:7 and heated at 155℃ for 12h to obtain sulfur / Ni-NiS2 heterostructure@porous carbon gel cathode material.

[0056] The sulfur / Ni-NiS2 heterostructure@porous carbon gel prepared in this embodiment exhibits a first-cycle discharge specific capacity of 1227 mAh g⁻¹ at a current density of 0.1 C. -1 It still maintains 620mAh after 100 cycles. -1 Specific capacity.

[0057] Example 3

[0058] (1) Add 1g of polyvinyl alcohol to a 20mL weighing bottle, then add 0.04g of nickel chloride to 5mL of deionized water, and then add it to the weighing bottle to mix with polyvinyl alcohol. Heat in a 40℃ water bath for 2h to obtain a hydrogel containing nickel chloride.

[0059] (2) Add 10 mL of graphene oxide solution with a concentration of 10 mg / mL to the hydrogel obtained in step (1) and stir at room temperature for 12 h to obtain a hydrogel-graphene oxide mixture.

[0060] (3) Dissolve 0.4g sodium sulfide in 5mL of deionized water. After it is completely dissolved, add it to the hydrogel-graphene oxide mixture obtained in step (2). Stir for 4 hours and then place it in a freeze dryer to dry overnight to obtain the precursor material.

[0061] (3) Place the precursor material from step (2) in a crucible and heat-treat it at 700°C for 2 hours in a tube furnace with argon atmosphere to finally obtain a multifunctional sulfur-fixing material with Ni-NiS2 heterostructure@porous carbon gel.

[0062] (4) The Ni-NiS2 heterostructure@porous carbon gel and sublimed sulfur powder were thoroughly ground and mixed. They were mixed in a mass ratio of 3:7 and heated at 155℃ for 12h to obtain sulfur / Ni-NiS2 heterostructure@porous carbon gel cathode material.

[0063] The sulfur / Ni-NiS2 heterostructure@porous carbon gel prepared in this embodiment exhibits a first-cycle discharge specific capacity of 1305 mAh g⁻¹ at a current density of 0.1 C. -1 After 100 cycles, it still maintains 637mAh g. -1 Specific capacity.

[0064] Example 4

[0065] (1) Add 1g of polyvinyl alcohol to a 20mL weighing bottle, then add 0.04g of nickel chloride to 5mL of deionized water, and then add it to the weighing bottle to mix with polyvinyl alcohol. Heat in a 40℃ water bath for 2h to obtain a hydrogel containing nickel chloride.

[0066] (2) Add 10 mL of graphene oxide solution with a concentration of 10 mg / mL to the hydrogel obtained in step (1) and stir at room temperature for 12 h to obtain a hydrogel-graphene oxide mixture.

[0067] (3) Dissolve 0.1g sodium sulfide in 5mL of deionized water. After it is completely dissolved, add it to the hydrogel-graphene oxide mixture obtained in step (2). Stir for 4 hours and then place it in a freeze dryer to dry overnight to obtain the precursor material.

[0068] (3) Place the precursor material from step (2) in a crucible and heat-treat it at 700°C for 2 hours in a tube furnace with argon atmosphere to finally obtain a multifunctional sulfur-fixing material with Ni-NiS2 heterostructure@porous carbon gel.

[0069] (4) The Ni-NiS2 heterostructure@porous carbon gel and sublimed sulfur powder were thoroughly ground and mixed. They were mixed in a mass ratio of 3:7 and heated at 155℃ for 12h to obtain sulfur / Ni-NiS2 heterostructure@porous carbon gel cathode material.

[0070] The sulfur / Ni-NiS2 heterostructure@porous carbon gel prepared in this embodiment exhibits a first-cycle discharge specific capacity of 1153 mAh g⁻¹ at a current density of 0.1 C. -1 It still maintains 580mAh after 100 cycles. -1 Specific capacity.

[0071] Example 5

[0072] (1) Add 1g of polyvinyl alcohol to a 20mL weighing bottle, then add 0.04g of nickel chloride to 5mL of deionized water, and then add it to the weighing bottle to mix with polyvinyl alcohol. Heat in a 40℃ water bath for 2h to obtain a hydrogel containing nickel chloride.

[0073] (2) Add 10 mL of graphene oxide solution with a concentration of 10 mg / mL to the hydrogel obtained in step (1) and stir at room temperature for 12 h to obtain a hydrogel-graphene oxide mixture.

[0074] (3) Dissolve 0.3g sodium sulfide in 5mL of deionized water. After it is completely dissolved, add it to the hydrogel-graphene oxide mixture obtained in step (2). Stir for 4 hours and then place it in a freeze dryer to dry overnight to obtain the precursor material.

[0075] (3) Place the precursor material from step (2) in a crucible and heat-treat it at 700°C for 2 hours in a tube furnace with argon atmosphere to finally obtain a multifunctional sulfur-fixing material with Ni-NiS2 heterostructure@porous carbon gel.

[0076] (4) The Ni-NiS2 heterostructure@porous carbon gel and sublimed sulfur powder were thoroughly ground and mixed. They were mixed in a mass ratio of 3:7 and heated at 155℃ for 12h to obtain sulfur / Ni-NiS2 heterostructure@porous carbon gel cathode material.

[0077] Figure 1 The image shows a scanning electron microscope (SEM) image of the Ni-NiS2@porous carbon gel prepared in Example 5. As can be seen from the image, a large number of macroporous structures appeared after high-temperature carbonization. These macroporous structures can effectively store sulfur active materials and alleviate their volume expansion problem during charge and discharge. At the same time, the nano-Ni-NiS2 heterostructure enhances the adsorption and catalytic ability of polysulfides and accelerates the reaction kinetics of lithium-sulfur batteries.

[0078] Figure 2 The X-ray diffraction pattern of the Ni-NiS2@porous carbon gel prepared in Example 5 is shown in the figure. As can be seen from the figure, the classic 002 carbon peak appears at 24.4°, which corresponds to the carbon peak of polyvinyl alcohol and graphene. At the same time, diffraction peaks corresponding to Ni and NiS2 are observed, which proves the successful preparation of Ni-NiS2@porous carbon gel.

[0079] Eighty parts of the sulfur / Ni-NiS2@porous carbon gel cathode material prepared in Example 5, 10 parts of conductive carbon Super-p, and 10 parts of binder PVDF were mixed and stirred. The mixed slurry was coated onto an aluminum foil current collector with a thickness of 100 micrometers. The solvent was removed by vacuum drying at 60°C for 25 hours to obtain the working electrode. This working electrode, along with a lithium foil anode, separator, and electrolyte, was assembled into a battery in a half-cell configuration. The assembly process was carried out entirely in a glove box under an argon atmosphere with an oxygen content of 0.01 ppm and a water content of 0.01 ppm. Electrochemical tests were performed on this lithium-sulfur battery. The voltage range was 1.6-2.8V, and the charge / discharge rates were 0.1C, 0.2C, 0.5C, 1C, and 2C.

[0080] Figure 3 This is a long-cycle graph of the sulfur / Ni-NiS2@porous carbon gel prepared in Example 5 after 100 cycles at 0.1C. As can be seen from the graph, at a current density of 0.1C (1C = 1675 mAh·g), the... -1 The first-cycle discharge specific capacity is 1545 mAh·g. -1 After 100 cycles, the capacity remains at 807 mAh·g. -1 With a capacity decay rate of 0.47%, it exhibits excellent cycle stability.

[0081] Figure 4 The scale diagrams for the sulfur / Ni-NiS2@porous carbon gel prepared in Example 5 at different scales show that the sulfur-fixing material exhibits excellent scale performance.

[0082] Example 6

[0083] Same as Example 5, except that in step (3), the sample is heat-treated at 900°C for 2 hours in a tubular furnace.

[0084] The sulfur / Ni-NiS2 heterostructure@porous carbon gel prepared in this embodiment exhibits a first-cycle discharge specific capacity of 1365 mAh g⁻¹ at a current density of 0.1 C. -1 After 100 cycles, it still maintains a capacity of 689mAh. -1 Specific capacity.

[0085] Comparative Example 1

[0086] Same as Example 5, except that in step (1), the amount of polyvinyl alcohol added is 2g.

[0087] The sulfur / Ni-NiS2@porous carbon gel prepared using this comparative example exhibits a first-cycle discharge specific capacity of 1120 mAh g⁻¹ at a current density of 0.1 C. -1 After 100 cycles, it maintains 523mAh g. -1 Specific capacity.

[0088] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a Ni-NiS2 heterostructure@porous carbon gel sulfur fixation material, characterized in that, Includes the following steps: (1) Polyvinyl alcohol, nickel chloride and deionized water are mixed and heated in a water bath to obtain a hydrogel containing nickel chloride; the ratio of polyvinyl alcohol, nickel chloride and deionized water is 1g:0.04g:(5-10)mL. (2) Add graphene oxide to the hydrogel obtained in step (1) and stir at room temperature to obtain a hydrogel-graphene oxide mixture; (3) Sodium sulfide is dissolved in deionized water to obtain a sodium sulfide solution, which is then added to the hydrogel-graphene oxide mixture obtained in step (2), stirred, and freeze-dried to obtain the precursor material; (4) Under an argon atmosphere, the precursor material was heat-treated at 700-900℃ for 2h to obtain Ni-NiS2 heterostructure@porous carbon gel sulfur fixation material. The mass ratio of sodium sulfide to nickel chloride added is 1-4:0.

4.

2. The preparation method of the Ni-NiS2 heterostructure@porous carbon gel sulfur fixation material according to claim 1, characterized in that, In step (1), the water bath heating is performed at 40°C for 1-4 hours.

3. A Ni-NiS2 heterostructure@porous carbon gel sulfur fixation material prepared by the preparation method of the Ni-NiS2 heterostructure@porous carbon gel sulfur fixation material according to any one of claims 1-2.

4. The application of the Ni-NiS2 heterostructure@porous carbon gel sulfur fixation material as described in claim 3 in the cathode material of lithium-sulfur batteries.

5. The application according to claim 4, characterized in that, The method for preparing the lithium-sulfur battery cathode material is as follows: Ni-NiS2 heterostructure@porous carbon gel sulfur fixation material and sublimed sulfur powder are mixed in a mass ratio of 3:7-1:9 and heated at 155℃ in an argon atmosphere for 12 hours to obtain sulfur / Ni-NiS2 heterostructure@porous carbon gel sulfur fixation cathode material.

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