A porous carbon-coated high-entropy metal nitride material, a preparation method therefor, and an application thereof

Abstract

The present application relates to a kind of porous carbon coated high-entropy metal nitride material and its preparation method and application.The material includes dodecahedron nitrogen-doped porous carbon, and high-entropy metal nitride uniformly dispersed on porous carbon.The preparation method is: using zinc-based zeolite imidazolate metal organic framework material as precursor, under the protection of silica shell pyrolysis forms dodecahedron nitrogen-doped porous carbon;After adsorbing a plurality of metal ions, porous carbon coated high-entropy metal nitride material is prepared by high-temperature heat treatment.The material is used as lithium-sulfur battery positive electrode sulfur carrier material.Compared with prior art, the composite material prepared by the present application combines the respective advantages of porous carbon and high-entropy metal nitride, so it has abundant pore structure, the synergistic effect of multiple active sites and stable chemical interface, and can produce excellent adsorption and catalysis on lithium polysulfide.

Description

Technical Field

[0001] This invention relates to the field of energy materials technology, specifically to a porous carbon-coated high-entropy metal nitride material, its preparation method, and its application. Background Technology

[0002] Energy is a vital resource for human survival. To achieve efficient energy utilization, energy storage technologies, especially secondary energy storage technologies, have emerged. Among all secondary energy storage technologies, rechargeable batteries are one of the most mature and widely used.

[0003] Currently, nickel-metal hydride batteries, lead-acid batteries, and lithium-ion batteries have all been successfully commercialized, with lithium-ion batteries holding a significant position in the energy storage market. However, with the in-depth development of lithium-ion batteries, the actual energy density of their positive and negative electrode materials has approached its theoretical limit, making it difficult to further meet the market's ever-growing demand for high energy density. Furthermore, the use of cobalt and nickel-containing metal-based materials in the positive electrode of lithium-ion batteries poses environmental pollution and recycling difficulties, which also severely restricts the large-scale application of lithium-ion batteries in the future energy storage field.

[0004] In light of this, numerous novel rechargeable battery systems have been developed, among which lithium-sulfur batteries, using sulfur as the positive electrode and lithium metal as the negative electrode, are considered one of the most promising new energy storage systems due to their various advantages. Benefiting from the specific capacity advantages of sulfur as the positive electrode and lithium metal as the negative electrode, the overall theoretical energy density of lithium-sulfur batteries reaches as high as 2500 Wh kg⁻¹, far exceeding the energy density of existing commercial lithium-ion batteries. At the same time, sulfur is widely available and inexpensive, possessing advantages such as environmental friendliness and easy recyclability. Although lithium-sulfur batteries exhibit outstanding advantages in energy density, manufacturing cost, and environmental compatibility, their practical application still faces many challenges.

[0005] The most obvious problems are low utilization of active materials, rapid capacity decay, and low coulombic efficiency. On the cathode side of lithium-sulfur batteries, these issues can be attributed to the low conductivity of sulfur and the discharge product lithium sulfide, the dissolution and shuttle effect of intermediate lithium polysulfides, the large electrode volume changes during charge and discharge, and the sluggish electrochemical conversion reaction. Therefore, finding a suitable sulfur carrier for the cathode is a crucial way to improve the performance of lithium-sulfur batteries. Summary of the Invention

[0006] The purpose of this invention is to overcome at least one of the defects of the prior art and provide a porous carbon-coated high-entropy metal nitride material with outstanding performance in the field of lithium-sulfur batteries, high specific capacity, low capacity decay rate, no need to introduce ammonia during preparation, economical and efficient, stable performance, green and environmentally friendly, and mass-producible, as well as its preparation method and application.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] The inventors believe that porous carbon materials offer advantages such as large specific surface area, high conductivity, and outstanding stability, but their ability to capture and catalytically convert lithium polysulfides is limited. Metal nitrides, on the other hand, possess strong chemisorption and excellent catalytic activity; however, limitations in their preparation methods and tendency to aggregate prevent the full exposure of active sites, thus restricting their effectiveness. Furthermore, high-entropy materials exhibit better thermodynamic stability due to their larger configurational entropy, and their diverse active sites demonstrate different specific preferences during catalysis. When used on the cathode side of lithium-sulfur batteries, they hold promise for improving the multi-step, multi-phase, and multi-electron-involved kinetics of delayed redox reactions.

[0009] Based on the above theoretical analysis, this invention combines the advantages of porous carbon and metal nitrides, and introduces the unique cocktail effect of high-entropy materials, that is, a synergistic effect brought about by the interaction between elements. The electronic structure specificity produced by this special combination of multiple elements enables high-entropy metal nitrides to exert unique advantages in complex catalytic reactions that are different from those of single-metal nitrides, thereby improving the overall performance of lithium-sulfur batteries. The specific scheme is as follows:

[0010] A porous carbon-coated high-entropy metal nitride material, comprising dodecahedral nitrogen-doped porous carbon and high-entropy metal nitride uniformly dispersed on the porous carbon.

[0011] Furthermore, the metal element of the high-entropy metal nitride includes at least one, or even four, of V, Mn, Ta, or Cr.

[0012] Furthermore, the molar ratios of all metallic elements are equal.

[0013] A method for preparing porous carbon-coated high-entropy metal nitride materials as described above, the method comprising:

[0014] Zinc-based zeolite imidazole ester metal-organic framework material is used as a precursor, and dodecahedral nitrogen-doped porous carbon is formed by pyrolysis under the protection of a silica shell.

[0015] After adsorbing multiple metal ions, porous carbon-coated high-entropy metal nitride materials are prepared by high-temperature heat treatment.

[0016] Specifically, a zinc-based zeolite imidazole ester metal-organic framework (ZIF-8) is used as a precursor. Under the protection of a silica shell, it undergoes pyrolysis to form dodecahedral nitrogen-doped porous carbon. After adsorbing various metal ions, this porous carbon is then subjected to high-temperature heat treatment to prepare a porous carbon-coated high-entropy metal nitride material. During the preparation process, the silica shell, due to its higher thermal stability compared to ZIF-8, provides a rigid framework support during the latter's pyrolysis. This facilitates the inheritance of the original dodecahedral morphology and the generation of a rich mesoporous structure during the formation of porous carbon. This structural morphology promotes the effective and uniform dispersion of nanoscale high-entropy metal nitride particles, resulting in efficient adsorption of lithium polysulfides. Without the protection of the silica shell, the pores of the porous carbon generated by the pyrolysis of ZIF-8 are concentrated in the micropore size range, which is detrimental to the loading of high-entropy metal nitrides and the adsorption of lithium polysulfides, thus affecting its electrochemical performance.

[0017] Furthermore, the specific preparation steps for dodecahedral nitrogen-doped porous carbon are as follows:

[0018] Zinc salt and dimethylimidazole were dissolved separately in solvents; then the two solutions were mixed and stirred, centrifuged to collect the ZIF-8 precipitate and dried.

[0019] The ZIF-8 precipitate was placed in water and ultrasonically dispersed. Then, a surfactant and an alkali were added, and ultrasonication was continued to form a ZIF-8 dispersion.

[0020] A mixed solution of organosilicon source and organic solvent was added dropwise to ZIF-8 dispersion. After stirring, the solution was added to water, the precipitate was collected by centrifugation and freeze-dried to obtain ZIF-8 coated with SiO2, denoted as ZIF-8@SiO2.

[0021] ZIF-8@SiO2 was heated in an inert atmosphere, and after cooling, the SiO2 on the surface was etched to obtain dodecahedral nitrogen-doped porous carbon, which served as a carrier for high-entropy metal nitrides.

[0022] Furthermore, the zinc salt is zinc nitrate hexahydrate, and the mass ratio of zinc salt to dimethylimidazole is (0.96-3.84):(2.356-9.424).

[0023] The surfactant is hexadecyltrimethylammonium bromide, and the alkali is sodium hydroxide. In the ZIF-8 dispersion, the mass ratio of ZIF-8 precipitate, surfactant, and alkali is (300-900):(75-300):(28.8-115.2).

[0024] The organosilicon source is tetraethyl orthosilicate, and the ratio of the organosilicon source to ZIF-8 precipitate is (1-3) mL:(300-900) mg.

[0025] Furthermore, the inert atmosphere is a nitrogen atmosphere, the heating temperature is 850-1050℃, and the time is 3-6h; the etching is performed using 5-20wt% HF etching.

[0026] Furthermore, the specific preparation steps for porous carbon-coated high-entropy metal nitrides are as follows:

[0027] The transition metal salt was dissolved by molar ratio, and dodecahedral nitrogen-doped porous carbon was added and ultrasonically dispersed.

[0028] After the solvent is evaporated by heating, the material is heated under an inert atmosphere and then cooled to obtain a porous carbon-coated high-entropy metal nitride material.

[0029] Furthermore, the transition metal salt includes one or more of VCl3, MnCl2, TaCl5 or CrCl3·3H2O, and the dodecahedral nitrogen-doped porous carbon is 1-4 times the total mass of the transition metal salt;

[0030] The inert atmosphere is nitrogen, and the heating temperature is 900-1100℃ for 1-4 hours.

[0031] An application of the porous carbon-coated high-entropy metal nitride material (HEMN / NC) as described above, which serves as a sulfur carrier material for the cathode of a lithium-sulfur battery.

[0032] Specifically, a composite sulfur cathode was prepared by loading 65 wt% elemental sulfur onto the material, with a lithium metal sheet as the anode, a Celgood 2400 polymer membrane as the separator, and a DOL / DME solution containing 1 M LiTFSI and 2 wt% LiNO3 as the electrolyte, and assembled into a CR2032 coin cell. Testing showed that the battery exhibited a high specific capacity and a low capacity decay rate during long-term charge-discharge cycles.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) In this invention, porous carbon-coated high-entropy metal nitride combines the advantages of porous carbon materials and high-entropy metal nitrides. The surface and interior of the material particles have abundant mesoporous structures and sufficient catalytic and adsorption sites. It has outstanding performance in the field of lithium-sulfur batteries, greatly improving the specific capacity of the battery and reducing the capacity decay rate of the battery.

[0035] (2) In the preparation process of this invention, metal nitrides can be obtained by heat treatment in a nitrogen atmosphere. Compared with the traditional metal nitride preparation process which requires the introduction of ammonia for nitriding, this process is more green and environmentally friendly and in line with the concept of sustainable development. This is because when introducing metal elements into the porous carbon support, this invention makes full use of its rich mesoporous structure, which effectively avoids the aggregation of metal elements and enables them to fully react with nitrogen in the form of nanoparticles with high specific surface area and high reactivity.

[0036] (3) This invention provides a new approach for preparing uniformly dispersed high-entropy nitrides. It is universal and can be applied to the process described above when introducing high-entropy nitride nanoparticles containing other types of metal elements into porous carbon materials.

[0037] (4) This invention provides an economical, efficient, stable, mass-producible porous carbon-coated high-entropy metal nitride material and its preparation method, and also includes the application of this material as a sulfur carrier material for the positive electrode of lithium-sulfur batteries. Attached Figure Description

[0038] Figure 1 This is a scanning electron microscope (SEM) image of the porous carbon-coated high-entropy metal nitride material prepared in Example 1.

[0039] Figure 2 This is a transmission electron microscope (TEM) image of the porous carbon-coated high-entropy metal nitride material prepared in Example 1;

[0040] Figure 3 The image shows the X-ray diffraction (XRD) pattern of the porous carbon-coated high-entropy metal nitride material prepared in Example 1.

[0041] Figure 4 The images show high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) images of the porous carbon-coated high-entropy metal nitride material prepared in Example 1, as well as EDS elemental distribution maps of C, N, Ta, Cr, V and Mn.

[0042] Figure 5 The rate performance curve of a lithium-sulfur battery prepared using the porous carbon-coated high-entropy metal nitride material prepared in Example 1 as the positive electrode sulfur support is shown.

[0043] Figure 6 The specific capacity decay curve of a lithium-sulfur battery prepared using the porous carbon-coated high-entropy metal nitride material prepared in Example 1 as the positive electrode sulfur support is shown.

[0044] Figure 7 The areal capacity decay curve of a lithium-sulfur battery prepared under high areal sulfur loading conditions using the porous carbon-coated high-entropy metal nitride material prepared in Example 2 as the positive electrode sulfur carrier. Detailed Implementation

[0045] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0046] A porous carbon-coated high-entropy metal nitride material, its preparation method, and its application, comprising the following specific steps:

[0047] (1) Preparation of dodecahedral nitrogen-doped porous carbon:

[0048] Dissolve 0.96-3.84 g of zinc nitrate hexahydrate and 2.356-9.424 g of dimethylimidazole in 25-100 mL of methanol respectively; then rapidly mix the two solutions, stir for 3-9 hours, centrifuge to collect the ZIF-8 precipitate and dry it in a forced-air oven; weigh 300-900 mg of the ZIF-8 sample prepared above and place it in a beaker containing 150-400 mL of deionized water, and sonicate for 10-30 minutes; then add 75-300 mg of cetyltrimethylammonium bromide and 28.8-115.2 mg of sodium hydroxide and continue sonicating for 5-20 minutes; then... -3 mL of a mixed solution of tetraethyl orthosilicate and 4-12 mL of methanol was added dropwise to the above ZIF-8 dispersion; after stirring for 15-60 minutes, the precipitate was collected by centrifugation with deionized water and freeze-dried to obtain a ZIF-8 sample coated with SiO2, denoted as ZIF-8@SiO2; the dried sample was placed in a crucible and then transferred to a tube furnace purged with nitrogen and heated at 850-1050℃ for 3-6 hours; after cooling to room temperature, the SiO2 on the surface of the material was removed by acid washing with 5-20 wt% HF to obtain a dodecahedral nitrogen-doped porous carbon material, which was used as a carrier for high-entropy metal nitrides.

[0049] (2) Preparation of porous carbon-coated high-entropy metal nitrides:

[0050] Weigh out and mix a certain amount of transition metal salts such as VCl3, MnCl2, TaCl5, and CrCl3·3H2O, wherein the molar ratio of the transition metal elements V, Mn, Ta, and Cr is approximately 1:1:1:1. Add the transition metal salt mixture to an open glass bottle containing ethanol and dissolve it by sonication. Then weigh out 1-4 times the mass of the prepared porous carbon and add it to the glass bottle, and continue to sonicate for 10-40 minutes. Next, place the glass bottle on a heated stirring table and heat and stir at 75-95°C until the ethanol solution is completely evaporated. Then transfer the dried sample to a tube furnace under a nitrogen atmosphere and heat at 900-1100°C for 1-4 hours. After cooling to room temperature, porous carbon coated with high-entropy metal nitrides is obtained.

[0051] The prepared porous carbon-coated high-entropy metal nitrides have good pore structure and outstanding specific surface area, while also possessing abundant lithium polysulfide catalytic and adsorption active sites, making them suitable as sulfur support materials for lithium-sulfur battery cathodes.

[0052] Specifically, a composite sulfur cathode was prepared by loading 65 wt% elemental sulfur onto the material, with a lithium metal sheet as the anode, a Celgood 2400 polymer membrane as the separator, and a DOL / DME solution containing 1 M LiTFSI and 2 wt% LiNO3 as the electrolyte, and assembled into a CR2032 coin cell. Testing showed that the battery exhibited a high specific capacity and a low capacity decay rate during long-term charge-discharge cycles.

[0053] Example 1

[0054] A porous carbon-coated high-entropy metal nitride material, its preparation method, and its application, comprising the following specific steps:

[0055] (1) Preparation of dodecahedral nitrogen-doped porous carbon: 1.9-2.0 g of zinc nitrate hexahydrate and 4.7-4.8 g of dimethylimidazole were dissolved in 50 mL of methanol respectively. The two solutions were then rapidly mixed and stirred for 6 hours. The ZIF-8 precipitate was collected by centrifugation and dried in a forced-air oven at 60 °C. 600 mg of the ZIF-8 sample prepared above was weighed and placed in a beaker containing 240 mL of deionized water and ultrasonically dispersed for 20 minutes. Then 150 mg of CTAB and 57.6 mg of NaOH were added and ultrasonication was continued for 10 minutes. Next, a mixed solution of 1.5 mL of tetraethyl orthosilicate and 6 mL of methanol was added dropwise to the above ZIF-8 dispersion. After stirring for 30 minutes, the precipitate was collected by centrifugation with deionized water and freeze-dried to obtain a ZIF-8 sample coated with SiO2 (ZIF-8@SiO2). The dried sample was placed in a crucible and then transferred to a tube furnace filled with nitrogen and heated at 950°C for 5 hours. After cooling to room temperature, the SiO2 on the surface of the material was removed by acid washing with 10wt% HF to obtain a dodecahedral nitrogen-doped porous carbon material, which was then used as a carrier for high-entropy metal nitrides.

[0056] (2) Preparation of porous carbon-coated high-entropy metal nitrides: 3 mg VCl3, 2.5 mg MnCl2, 7 mg TaCl5, and 6.7 mg CrCl3·6H2O were weighed and added to an open glass bottle containing 4 mL of ethanol and dissolved by sonication. Then, 50 mg of the porous carbon prepared above was added and sonicated for another 20 minutes. Next, the glass bottle was placed on a heated stirring table and heated and stirred at 85 °C until the ethanol solution was completely evaporated. The dried sample was then transferred to a tube furnace under a nitrogen atmosphere and heated at 1000 °C for 2 hours. After cooling to room temperature, porous carbon-coated high-entropy metal nitrides were obtained.

[0057] After loading 65 wt% elemental sulfur onto the material to prepare a composite sulfur cathode, a lithium metal sheet was used as the anode, a Celgood 2400 polymer membrane as the separator, and a DOL / DME solution containing 1 M LiTFSI and 2 wt% LiNO3 was used as the electrolyte to assemble a CR2032 coin cell. Testing was conducted under conventional sulfur loading and electrolyte addition conditions. Its morphology and performance are shown below. Figures 1-6 As shown.

[0058] Figure 1 It can be observed that the porous carbon-coated high-entropy metal nitride, namely HEMN@NC, has a regular dodecahedral morphology.

[0059] Figure 2 The middle circle indicates high-entropy metal nitride particles at the nanoscale, which are located in the abundant mesopores of the porous carbon support, achieving an effective and uniform distribution and providing sufficient sites for the catalysis and adsorption of lithium polysulfides.

[0060] Figure 3 XRD spectral lines further confirmed the presence of HEMN and Ta. 1 / 3 Mn 1 / 3 V 1 / 3 N and VN have similar crystal structures, but their interplanar spacings differ. Among them, the preparation of Ta... 1 / 3 Mn 1 / 3 V 1 / 3 The methods for preparing N@NC and VN@NC are similar to those for preparing HEMN@NC, except that Ta 1 / 3 Mn 1 / 3 V 1 / 3 N@NC only added 3mg VCl3, 2.5mg MnCl2, and 7mg TaCl5 during the introduction of metal elements, while VN@NC only added 12mg VCl3 during the introduction of metal elements.

[0061] Figure 4The EDS elemental distribution shows that V, Mn, Ta, Cr and other metal elements are uniformly distributed in HEMN@NC, which corroborates the formation of high-entropy metal nitrides.

[0062] Figure 5 The results show that S / HEMN@NC, as the active material for the cathode of lithium-sulfur batteries, has average discharge specific capacities of 1261, 1076, 954, 813, and 650 mAh g⁻¹ at 0.2C, 0.5C, 1C, 2C, and 5C rates, respectively. -1 This indicates that the material prepared by this invention has fewer metal components compared to S / Ta. 1 / 3 Mn 1 / 3 V 1 / 3 Lithium-sulfur batteries using N@NC and S / VN@NC materials as cathode materials can significantly improve battery capacity.

[0063] Figure 6 The results show that S / HEMN@NC, as the active material of the positive electrode in lithium-sulfur batteries, can maintain a capacity of 1107 mAh g / L after 100 cycles at a rate of 0.2C. -1 Its high specific capacity and capacity retention of 86.9% are higher than those of S / Ta. 1 / 3 Mn 1 / 3 V 1 / 3 The lithium-sulfur battery composed of N@NC and S / VN@NC as positive electrode active materials shows that the lithium-sulfur battery obtained by the materials prepared in this invention has excellent cycle stability and low capacity decay rate.

[0064] Example 2

[0065] A porous carbon-coated high-entropy metal nitride material, its preparation method, and its application, comprising the following specific steps:

[0066] (1) Preparation of dodecahedral nitrogen-doped porous carbon: 1.9-2.0 g of zinc nitrate hexahydrate and 4.7-4.8 g of dimethylimidazole were dissolved in 50 mL of methanol respectively. The two solutions were then rapidly mixed and stirred for 6 hours. The ZIF-8 precipitate was collected by centrifugation and dried in a forced-air oven at 60 °C. 600 mg of the ZIF-8 sample prepared above was weighed and placed in a beaker containing 240 mL of deionized water and ultrasonically dispersed for 20 minutes. Then 150 mg of CTAB and 57.6 mg of NaOH were added and ultrasonication was continued for 10 minutes. Next, a mixed solution of 1.5 mL of tetraethyl orthosilicate and 6 mL of methanol was added dropwise to the above ZIF-8 dispersion. After stirring for 30 minutes, the precipitate was collected by centrifugation with deionized water and freeze-dried to obtain a ZIF-8 sample coated with SiO2 (ZIF-8@SiO2). The dried sample was placed in a crucible and then transferred to a tube furnace filled with nitrogen and heated at 950°C for 5 hours. After cooling to room temperature, the SiO2 on the surface of the material was removed by acid washing with 10wt% HF to obtain a dodecahedral nitrogen-doped porous carbon material, which was then used as a carrier for high-entropy metal nitrides.

[0067] (2) Preparation of porous carbon-coated high-entropy metal nitrides: 3 mg VCl3, 2.5 mg MnCl2, 7 mg TaCl5, and 6.7 mg CrCl3·6H2O were weighed and added to an open glass bottle containing ethanol and dissolved by sonication. Then, 50 mg of the porous carbon prepared above was added and sonicated for another 20 minutes. Next, the glass bottle was placed on a heated stirring table and heated and stirred at 85 °C until the ethanol solution was completely evaporated. The dried sample was then transferred to a tube furnace under a nitrogen atmosphere and heated at 1100 °C for 2 hours. After cooling to room temperature, porous carbon-coated high-entropy metal nitrides were obtained.

[0068] After loading the material with 65 wt% elemental sulfur to prepare a composite sulfur cathode, a lithium metal sheet was used as the anode, a Celgood 2400 polymer membrane as the separator, and a DOL / DME solution containing 1 M LiTFSI and 2 wt% LiNO3 was used as the electrolyte to assemble a CR2032 coin cell. This cell was then tested at a high sulfur loading (5.0 mg / cm²). -2 ) and low electrolyte addition (8.0 μL mg) -1 The test was conducted under the following conditions. Its morphology is similar to that of Example 1, and its performance is as described above. Figure 7 . Figure 7 The display shows that it can maintain a 5.0 mAh capacity after 100 cycles. -2 Area capacity.

[0069] In summary, the composite material prepared by this invention combines the advantages of both porous carbon and high-entropy metal nitrides, thus possessing a rich pore structure, synergistic effects of multiple active sites, and a stable chemical interface, and exhibiting excellent adsorption and catalytic effects on lithium polysulfides. Therefore, when this composite material is used as a sulfur support material for the cathode of lithium-sulfur batteries, it demonstrates high specific capacity and long cycle life. The preparation process of this invention is simple and environmentally friendly, the preparation conditions are easy to meet, and the preparation cost is low.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing porous carbon-coated high-entropy metal nitride materials, characterized in that, The material comprises dodecahedral nitrogen-doped porous carbon and high-entropy metal nitrides uniformly dispersed on the porous carbon. The preparation method is as follows: Zinc-based zeolite imidazole ester metal-organic framework material is used as a precursor, and dodecahedral nitrogen-doped porous carbon is formed by pyrolysis under the protection of a silica shell. The transition metal salt was dissolved by molar ratio, and dodecahedral nitrogen-doped porous carbon was added and ultrasonically dispersed. The dodecahedral nitrogen-doped porous carbon is 1-4 times the total mass of the transition metal salt; After the solvent is evaporated by heating, the material is heated under an inert atmosphere and then cooled to obtain a porous carbon-coated high-entropy metal nitride material. The inert atmosphere is a nitrogen atmosphere, the heating temperature is 900-1100℃, and the heating time is 1-4 h. The metal elements of the high-entropy metal nitride include V, Mn, Ta, and Cr in equimolar ratios.

2. The method for preparing a porous carbon-coated high-entropy metal nitride material according to claim 1, characterized in that, The specific preparation steps for dodecahedral nitrogen-doped porous carbon are as follows: Zinc salt and dimethylimidazole were dissolved separately in solvents; then the two solutions were mixed and stirred, centrifuged to collect the ZIF-8 precipitate and dried. The ZIF-8 precipitate was placed in water and ultrasonically dispersed. Then, a surfactant and an alkali were added, and ultrasonication was continued to form a ZIF-8 dispersion. A mixed solution of organosilicon source and organic solvent was added dropwise to ZIF-8 dispersion. After stirring, the solution was added to water, the precipitate was collected by centrifugation and freeze-dried to obtain ZIF-8 coated with SiO2, denoted as ZIF-8@SiO2. ZIF-8@SiO2 was heated in an inert atmosphere, and after cooling, the SiO2 on the surface was etched to obtain dodecahedral nitrogen-doped porous carbon, which served as a carrier for high-entropy metal nitrides.

3. The method for preparing a porous carbon-coated high-entropy metal nitride material according to claim 2, characterized in that, The zinc salt is zinc nitrate hexahydrate, and the mass ratio of zinc salt to dimethylimidazole is (0.96-3.84): (2.356-9.424). The surfactant is hexadecyltrimethylammonium bromide, and the alkali is sodium hydroxide. In the ZIF-8 dispersion, the mass ratio of ZIF-8 precipitate, surfactant, and alkali is (300-900): (75-300): (28.8-115.2). The organosilicon source is tetraethyl orthosilicate, and the ratio of the organosilicon source to ZIF-8 precipitate is (1-3) mL: (300-900) mg.

4. The method for preparing a porous carbon-coated high-entropy metal nitride material according to claim 2, characterized in that, When ZIF-8@SiO2 is heated in an inert atmosphere, namely nitrogen atmosphere, the heating temperature is 850-1050℃ and the time is 3-6 h; etching is performed using 5-20wt% HF.

5. The method for preparing a porous carbon-coated high-entropy metal nitride material according to claim 1, characterized in that, The transition metal salts mentioned include VCl3, MnCl2, TaCl5, and CrCl3·3H2O.

6. An application of a porous carbon-coated high-entropy metal nitride material prepared by the method according to any one of claims 1-5, characterized in that, This material serves as a sulfur carrier for the cathode in lithium-sulfur batteries.

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