A high-entropy intermetallic compound nanomaterial, its preparation method and application
By preparing high-entropy intermetallic compound nanomaterials, the problems of few active centers and large size in nanocatalytic materials were solved, achieving efficient catalysis with multiple reaction branches and significantly improving the performance of lithium-sulfur batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN NORMAL UNIVERSITY
- Filing Date
- 2024-04-08
- Publication Date
- 2026-07-17
AI Technical Summary
Existing nanocatalytic materials have few types of active centers, large size, and low catalytic efficiency, making it difficult to simultaneously and optimally control multiple electron/ion/proton reactions.
High-entropy intermetallic compound nanomaterials were prepared using five elements: Fe, Co, Ni, Pt, and Cu. Pt occupied the vertices of the face-centered cubic structure, while Fe, Co, Ni, and Cu randomly occupied the face-centered positions. The PtCu3 phase structure was formed by in-situ synthesis using hollow carbon spheres and was uniformly distributed on the surface of the hollow carbon spheres.
It provides multiple types of active centers, improves material utilization, exhibits high entropy effect and lattice distortion effect, can catalyze multiple reaction branches simultaneously, exhibits catalytic performance over a wide energy range, and significantly improves the cycle stability and capacity of lithium-sulfur batteries.
Smart Images
Figure CN118341442B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a high-entropy alloy nanomaterial, its preparation method, and its application. Background Technology
[0002] Catalysts, as substances that accelerate chemical reaction rates, are hailed as the "heart" of modern chemical industry and are widely used in over 90% of chemical processes. High-entropy materials typically consist of five or more metallic active sites, each with a content between 5% and 35%. Compared to traditional binary or ternary catalysts, high-entropy catalysts offer significant advantages in lithium-sulfur batteries due to their unique multi-component synergistic regulatory effect. First, the multi-elemental composition of high-entropy catalysts can provide diverse active centers, lowering the reaction energy barrier and accelerating electrochemical reaction kinetics. Second, the proximity of various elements in high-entropy catalysts provides a unique opportunity to develop novel and tunable active sites. By precisely controlling the compositional elements and proportions of the material, the activity of these sites can be targeted and optimized. Therefore, high-entropy catalysts break through the barrier of limited active sites in traditional catalysts, opening up a vast compositional space for the design of multi-site catalysts, demonstrating significant advantages and broad prospects in applications involving multiple electron / ion / proton reactions, such as lithium-sulfur batteries.
[0003] For catalytic materials, smaller size and larger specific surface area facilitate better contact between the catalytic material and reactants, thereby enabling the catalytic material to regulate reaction rates. Due to limitations in previous preparation methods and processes, existing nanocatalytic materials are either large in size or contain only one or two types of active centers. On the one hand, larger sizes do not allow for the full utilization of the material's catalytic effect, resulting in wasted active centers and increased production costs. On the other hand, a single active center can only effectively regulate one reaction, not simultaneously and optimally regulate different reactions. In other words, for multi-step cascade reactions involving multiple electrons / ions / protons, a limited number of active centers cannot simultaneously and optimally regulate the rates of each branch of the reaction. Therefore, finding a low-temperature method for the precise preparation of high-entropy (sub)nanomaterials with controllable structure and composition remains a challenge in the field of materials science. Summary of the Invention
[0004] The purpose of this invention is to address the problems of limited types, large sizes, and low catalytic efficiency of existing nanocatalytic materials, and to provide a high-entropy intermetallic compound nanomaterial, its preparation method, and its application.
[0005] A high-entropy intermetallic compound nanomaterial is in the form of particles and is composed of five elements: Fe, Co, Ni, Pt, and Cu. It has a PtCu3 phase structure, in which Pt occupies the vertices of the face-centered cubic structure, while Fe, Co, Ni, and Cu randomly occupy the face centers of the face-centered cubic structure.
[0006] A method for preparing high-entropy intermetallic compound nanomaterials is specifically carried out according to the following steps:
[0007] I. Preparation of hollow carbon spheres:
[0008] ① Mix anhydrous ethanol, deionized water and NH3·H2O, stir for a period of time, then add tetraethyl silicate dropwise, and finally add a mixture of resorcinol and formaldehyde to obtain solution A;
[0009] ② Stir solution A continuously for a period of time, then transfer it to a high-pressure reactor lined with Teflon for hydrothermal reaction. After the reaction is completed, centrifuge and dry to obtain product A. Calcinate product A in N2 atmosphere at a temperature of 750℃~850℃ for a period of time to obtain product B. Immerse product B in NaOH solution for a period of time to remove SiO2 spheres and obtain hollow carbon spheres.
[0010] II. In-situ synthesis of high-entropy intermetallic compound nanomaterials on hollow carbon spheres:
[0011] H₂PtCl₆·6H₂O, FeCl₂·4H₂O, NiCl₂·6H₂O, CoCl₂·6H₂O, and CuCl₂·2H₂O were added to deionized water and sonicated to form a homogeneous solution, resulting in a mixed solution. Hollow carbon spheres were added to the mixed solution, stirred for a period of time, and then evaporated to dryness using a rotary evaporator. The solution was then transferred to a tube furnace and heated for a period of time in a mixed atmosphere of H₂ and Ar at a temperature of 950℃~1000℃ to obtain high-entropy intermetallic compound nanomaterials uniformly distributed on the surface of the hollow carbon spheres.
[0012] A high-entropy intermetallic compound nanomaterial is used as a positive electrode catalyst in lithium-sulfur batteries.
[0013] Effects of the invention:
[0014] I. The high-entropy intermetallic compound nanomaterial obtained by this invention is in the form of particles with a nanoscale particle size (less than 10 nm, with an average diameter of ~4 nm), which is beneficial for exposing more active sites and improving the utilization rate of the material.
[0015] II. The high-entropy intermetallic compound nanomaterial obtained by this invention is composed of five elements: Fe, Co, Ni, Pt, and Cu (the content of each element is between 5% and 35%), with a mixing entropy value ≥1.5R. It belongs to high-entropy materials and can exhibit high-entropy effect, lattice distortion effect, diffusion lag effect, and cocktail effect.
[0016] Third, the multi-element composition of the high-entropy intermetallic compound nanomaterial obtained by this invention can provide various types of active centers, which can selectively catalyze different reaction branches of multiple electron / ion / proton reactions.
[0017] Fourth, the high-entropy intermetallic compound nanomaterial obtained by this invention has a unique opportunity to precisely modulate the catalytic performance of active sites due to the proximity of various different elements; by precisely controlling the proportion of constituent elements, the catalytic activity of the sites can be optimized, thereby effectively controlling the transformation behavior of chemical reactions.
[0018] V. Compared with the discrete energy levels of elemental metals, the high-entropy intermetallic compound nanomaterial obtained by this invention exhibits a significantly broadened valence band and a continuously distributed band structure, which is beneficial for catalytic conversion of multiple electron / ion / proton reactions over a wide energy range.
[0019] VI. The high-entropy intermetallic compound nanomaterial obtained by this invention has a PtCu3 phase structure (JCPDS 65–33247), in which Pt element occupies the vertices of the face-centered cubic structure, while Fe, Co, Ni and Cu elements randomly occupy the face-centered positions of the face-centered cubic structure; in this structure, Pt element forms an ordered superlattice structure, which is equivalent to Pt single atoms on a metal support composed of the other four elements, and can better exert the catalytic effect of Pt;
[0020] VII. The high-entropy intermetallic compound nanomaterial obtained by this invention is uniformly distributed on the surface of hollow carbon spheres and has good intrinsic electronic / ionic conductivity.
[0021] 8. The high-entropy intermetallic compound nanomaterial obtained by this invention is uniformly distributed in hollow carbon spheres, exhibiting good wettability to solutions and achieving excellent catalytic performance;
[0022] IX. A high-entropy intermetallic compound nanomaterial obtained in this invention, when used as a cathode host in a lithium-sulfur battery, exhibits a capacitance of 1290.2 mAh g⁻¹ at 0.1C. -1 Initial capacity and excellent cycling stability. After 3000 cycles at 1C, the average capacity decay rate per cycle is only 0.03%. Furthermore, at 9 mg / cm³... -2 Under high sulfur loading, the initial areal capacity can reach 10.2 mAh / cm³. -2The areal capacity remains at 8.5 mAh cm⁻¹ during 35 cycles. -2 above;
[0023] 10. The high-entropy intermetallic compound nanomaterial obtained by this invention has an ingenious preparation process, is simple and easy to operate, has excellent performance, and is conducive to commercial production.
[0024] XI. The high-entropy intermetallic compound nanomaterial obtained by this invention has broad application prospects in many fields involving multiple electron / ion / proton reactions. Attached Figure Description
[0025] Figure 1 The image shown is a scanning electron microscope image of product B prepared in step 1② of Example 1.
[0026] Figure 2 The image shows a scanning electron microscope (SEM) image of the hollow carbon spheres prepared in step 1② of Example 1.
[0027] Figure 3 The X-ray diffraction pattern of the high-entropy intermetallic compound nanomaterial distributed on the surface of hollow carbon spheres prepared in Example 1;
[0028] Figure 4 This is a low-magnification transmission electron microscope image of the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1;
[0029] Figure 5 The statistical results of particle distribution of the high-entropy intermetallic compound nanomaterials prepared in Example 1 are shown.
[0030] Figure 6 The energy spectrum and composition of the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1 are shown below.
[0031] Figure 7 The image shows the elemental distribution of the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1.
[0032] Figure 8 This is a high-magnification transmission electron microscope image of the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1;
[0033] Figure 9 The two-dimensional interplanar spacing is shown in a high-magnification transmission electron microscope image of the high-entropy intermetallic compound nanomaterial distributed on the surface of hollow carbon spheres prepared in Example 1.
[0034] Figure 10 The Fourier transform results of a high-magnification transmission electron microscope image of the high-entropy intermetallic compound nanomaterial distributed on the surface of hollow carbon spheres prepared in Example 1;
[0035] Figure 11 The cycle characteristics of lithium-sulfur batteries under 0.1C conditions;
[0036] Figure 12 The cycle characteristics of lithium-sulfur batteries under 1C conditions;
[0037] Figure 13 High sulfur loading (9 mg / cm³) -2 Cycling characteristics of lithium-sulfur batteries under 0.1C conditions. Detailed Implementation
[0038] Specific Implementation Method 1: In this implementation method, a high-entropy intermetallic compound nanomaterial is in the form of particles, composed of five elements: Fe, Co, Ni, Pt, and Cu. It has a PtCu3 phase structure, in which the Pt element occupies the vertex position of the face-centered cubic structure, while the four elements Fe, Co, Ni, and Cu randomly occupy the face center positions of the face-centered cubic structure.
[0039] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the high-entropy intermetallic compound nanomaterial is composed of five elements: Fe, Co, Ni, Pt, and Cu, with each element comprising 5% to 35% by mass; the particle size of the high-entropy intermetallic compound nanomaterial is less than 10 nm. Other steps are the same as in Specific Implementation Method One.
[0040] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: a method for preparing high-entropy intermetallic compound nanomaterials is completed according to the following steps:
[0041] I. Preparation of hollow carbon spheres:
[0042] ① Mix anhydrous ethanol, deionized water and NH3·H2O, stir for a period of time, then add tetraethyl silicate dropwise, and finally add a mixture of resorcinol and formaldehyde to obtain solution A;
[0043] ② Stir solution A continuously for a period of time, then transfer it to a high-pressure reactor lined with Teflon for hydrothermal reaction. After the reaction is completed, centrifuge and dry to obtain product A. Calcinate product A in N2 atmosphere at a temperature of 750℃~850℃ for a period of time to obtain product B. Immerse product B in NaOH solution for a period of time to remove SiO2 spheres and obtain hollow carbon spheres.
[0044] II. In-situ synthesis of high-entropy intermetallic compound nanomaterials on hollow carbon spheres:
[0045] H₂PtCl₆·6H₂O, FeCl₂·4H₂O, NiCl₂·6H₂O, CoCl₂·6H₂O, and CuCl₂·2H₂O were added to deionized water and sonicated to form a homogeneous solution, resulting in a mixed solution. Hollow carbon spheres were added to the mixed solution, stirred for a period of time, and then evaporated to dryness using a rotary evaporator. The solution was then transferred to a tube furnace and heated for a period of time under a mixed atmosphere of H₂ and Ar at a temperature of 950℃~1000℃ to obtain high-entropy intermetallic compound nanomaterials uniformly distributed on the surface of the hollow carbon spheres. Other steps are the same as in specific implementation method one or two.
[0046] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the volume ratio of anhydrous ethanol, deionized water, NH3·H2O, and tetraethyl silicate in step one ① is (60mL~80mL):(5mL~15mL):(2mL~4mL):(2mL~3mL); the mass ratio of resorcinol to formaldehyde in the mixture of resorcinol and formaldehyde in step one ① is (0.3g~0.5g):(0.4mL~0.7mL). The other steps are the same as in Specific Implementation Methods One to Three.
[0047] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in the following ways: In step one ①, the volume ratio of anhydrous ethanol to methanol in the mixture of resorcinol and formaldehyde is (60mL~80mL):(0.4mL~0.7mL); the stirring temperature in step one ① is 30℃~40℃, and the stirring time is 20min~40min; the rate at which tetraethyl silicate is added dropwise in step one ① is 20 drops / min~40 drops / min. Other steps are the same as in Specific Implementation Methods One to Four.
[0048] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step one, solution A is continuously stirred at 30°C to 40°C for 20 to 24 hours; the hydrothermal reaction temperature in step one, step two is 90°C to 110°C, and the hydrothermal reaction time is 20 to 24 hours. Other steps are the same as in Specific Implementation Methods One to Five.
[0049] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in the following ways: the calcination time in step one to two is 1 to 3 hours; the concentration of the NaOH solution in step one to two is 2 to 3 mol / L; and the time for immersing product B in the NaOH solution in step one to two is 3 to 5 days. The other steps are the same as in Specific Implementation Methods One to Six.
[0050] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the high-entropy intermetallic compound nanomaterial described in step two is composed of five elements: Fe, Co, Ni, Pt, and Cu, with each element having a mass fraction of 5% to 35%; the mass-to-volume ratio of H₂PtCl₆·6H₂O, hollow carbon spheres, and deionized water described in step two is (30mg–50mg):(90mg–100mg):100mL. Other steps are the same as in Specific Implementation Methods One to Seven.
[0051] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in the following ways: In step two, hollow carbon spheres are added to the mixed solution, and the stirring time is 10-12 hours; in step two, the volume ratio of H2 to Ar in the mixed atmosphere is 5:100; in step two, the heating time in the mixed atmosphere of H2 and Ar at a temperature of 950°C-1000°C is 1-3 hours. The other steps are the same as in Specific Implementation Methods One to Eight.
[0052] Specific Implementation Method 10: This implementation method is to use a high-entropy intermetallic compound nanomaterial as a positive electrode catalyst material in a lithium-sulfur battery.
[0053] The beneficial effects of the present invention are verified using the following embodiments:
[0054] Example 1: A method for preparing a high-entropy intermetallic compound nanomaterial, specifically carried out according to the following steps:
[0055] I. Preparation of hollow carbon spheres:
[0056] ① Mix 70 mL of anhydrous ethanol, 10 mL of deionized water and 3 mL of NH3·H2O, stir at 30 °C for 30 min, then add 2.8 mL of tetraethyl silicate dropwise at a rate of 30 drops / min, and finally add a mixture of resorcinol and formaldehyde (0.4 g of resorcinol and 0.56 mL of formaldehyde) to obtain solution A;
[0057] ② Solution A was continuously stirred at 30℃ for 24 hours, then transferred to a high-pressure reactor lined with Teflon and hydrothermally reacted at 100℃ for 24 hours. After the reaction, it was centrifuged and dried to obtain product A (a SiO2 nano-core-shell structure with an outer layer of resorcinol-formaldehyde resin); product A was calcined in a N2 atmosphere at 800℃ for 2 hours to obtain product B (a SiO2 nano-core-shell structure with an outer layer of carbon); product B was immersed in a 2.8 mol / L NaOH solution for 4 days to remove the SiO2 spheres and obtain hollow carbon spheres.
[0058] II. In-situ synthesis of high-entropy intermetallic compound nanomaterials on hollow carbon spheres:
[0059] 41.94 mg H2PtCl6·6H2O, 19.53 mg FeCl2·4H2O, 23.38 mg NiCl2·6H2O, 23.38 mg CoCl2·6H2O, and 16.8 mg CuCl2·2H2O were added to 100 mL of deionized water and sonicated to form a homogeneous solution, resulting in a mixed solution. 100 mg of hollow carbon spheres were added to the mixed solution, stirred for 12 h, and then evaporated to dryness using a rotary evaporator. The solution was then transferred to a tube furnace and heated for 2 h in a mixed atmosphere of H2 and Ar at 1000 °C to obtain a high-entropy intermetallic compound nanomaterial (HEA@HC) uniformly distributed in the hollow carbon spheres.
[0060] In step two, the volume ratio of H2 to Ar in the mixed atmosphere is 5:100.
[0061] Figure 1 The image shown is a scanning electron microscope image of product B prepared in step 1② of Example 1.
[0062] Figure 2 The image shows a scanning electron microscope (SEM) image of the hollow carbon spheres prepared in step 1② of Example 1.
[0063] from Figure 1 , Figure 2 As can be seen, the SiO2 spheres in product B have been removed, and the carbon spheres have a hollow structure.
[0064] Figure 3 The X-ray diffraction pattern of the high-entropy intermetallic compound nanomaterial distributed on the surface of hollow carbon spheres prepared in Example 1;
[0065] from Figure 3 As can be seen, the high-entropy intermetallic compound nanoparticles distributed on the surface of the hollow carbon spheres have a face-centered cubic structure, which is an intermetallic compound of the PtCu3 (JCPDS 65–33247) phase. Pt occupies the vertices of the face-centered cubic structure, while Fe, Co, Ni, and Cu randomly occupy the face-centered positions. In this structure, Pt forms an ordered superlattice structure, equivalent to single Pt atoms on a metal support composed of the other four elements, thus better leveraging the catalytic effect of Pt.
[0066] Figure 4 This is a low-magnification transmission electron microscope image of the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1;
[0067] Figure 5 The statistical results of particle distribution of the high-entropy intermetallic compound nanomaterials prepared in Example 1 are shown.
[0068] from Figure 4-5As can be seen, the high-entropy intermetallic compound nanomaterials prepared in Example 1 are particles uniformly distributed on the surface of hollow carbon spheres. The hollow structure of the carbon spheres exhibits good wettability to the solution, which is beneficial for obtaining excellent catalytic performance. At the same time, the high-entropy intermetallic compound nanoparticles have a nanoscale particle size (less than 10 nm, with an average diameter of ~4 nm), which is beneficial for exposing more active sites and improving the utilization rate of the material.
[0069] Figure 6 The energy spectrum and composition of the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1 are shown below.
[0070] Figure 7 The image shows the elemental distribution of the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1.
[0071] from Figure 6-7 As can be seen, the high-entropy intermetallic compound nanomaterials prepared in Example 1, distributed uniformly on the surface of hollow carbon spheres, are composed of five elements: Fe, Co, Ni, Pt, and Cu. The contents of Fe, Co, Ni, Pt, and Cu are approximately 15%, 15%, 20%, 25%, and 25%, respectively, with a mixing entropy value ≥1.5R, classifying them as high-entropy materials. These materials exhibit high-entropy effects, lattice distortion effects, diffusion retardation effects, cocktail effects, and a significantly broadened valence band and continuously distributed band structure. These particles can provide various types of active centers, enabling targeted catalysis of different reaction branches of multiple electron / ion / proton reactions. The proximity of various elements provides a unique opportunity for precisely modulating the catalytic performance of active sites. By precisely controlling the proportions of the constituent elements, the catalytic activity of the sites can be optimized, thereby effectively regulating the transformation behavior of chemical reactions.
[0072] Figure 8 This is a high-magnification transmission electron microscope image of the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1;
[0073] Figure 9 The two-dimensional interplanar spacing is shown in a high-magnification transmission electron microscope image of the high-entropy intermetallic compound nanomaterial distributed on the surface of hollow carbon spheres prepared in Example 1.
[0074] Figure 10 The Fourier transform results of a high-magnification transmission electron microscope image of the high-entropy intermetallic compound nanomaterial distributed on the surface of hollow carbon spheres prepared in Example 1;
[0075] from Figure 8-10 As can be seen, the nanoparticles distributed on the surface of the hollow carbon spheres are intermetallic compounds of the PtCu3 (JCPDS 65–33247) phase, and their crystal structure contains a large number of lattice distortions, which can exhibit lattice distortion effects.
[0076] Cultivating Rhizopus mycelial balls: Rhizopus was inoculated onto solid potato dextrose agar (PDA) medium and cultured at 28°C for 48 hours. The cultured Rhizopus mycelia were then inoculated onto Sabouraud dextrose agar (SDB) medium and transferred to a shaker. The mixture was initially incubated at 28°C and 130 rpm. -1 Under the same conditions for 24 hours, the rotation speed was then increased to 155 rpm. -1 Keep it for 24 hours.
[0077] Preparation of carbon substrate: Rhizopus mycelium balls were soaked in anhydrous ethanol and washed with deionized water until neutral; the washed Rhizopus mycelium balls were freeze-dried for 48 hours. The freeze-dried mycelium balls were annealed at 800℃ under N2 conditions for 2 hours to obtain a carbon substrate (HCNB) with a self-supporting structure.
[0078] Electrode preparation:
[0079] The high-entropy intermetallic compound nanomaterial (HEA@HC) uniformly distributed in hollow carbon spheres prepared in Example 1 was mixed with elemental sulfur (S) at a mass ratio of 7:3, sealed, and heated at 155°C for 12 hours to obtain the composite material / HEA@HC. The composite material / HEA@HC, polyvinylidene fluoride (PVDF), and conductive carbon black (Super P) were mixed in N-methylpyrrolidone (NMP) at a mass ratio of 8:1:1 to form a homogeneous slurry A. For ease of dissolution, the mass of PVDF in NMP was controlled at 5 wt.%. Slurry A was then dropped onto a self-supporting carbon substrate (HCNB) to achieve a sulfur loading of approximately 1 mg / cm³. -1 The electrode S / HEA@HC / HCNB was obtained.
[0080] The preparation of hollow carbon sphere electrodes S / HC / HCNB without high-entropy intermetallic compound nanoparticles was carried out according to the following steps:
[0081] Hollow carbon spheres prepared in step one of Example 1 and elemental sulfur (S) were mixed at a mass ratio of 7:3, sealed, and heated at 155°C for 12 hours to obtain a composite material. The composite material, polyvinylidene fluoride (PVDF), and conductive carbon black (SuperP) were mixed in N-methylpyrrolidone (NMP) at a mass ratio of 8:1:1 to form a homogeneous slurry A. For ease of dissolution, the mass of PVDF in NMP was controlled to be 5 wt.%. Slurry A was then dropped onto a carbon substrate (HCNB) with a self-supporting structure to obtain a hollow carbon sphere electrode S / HC / HCNB without high-entropy intermetallic compound nanoparticles.
[0082] Assembly and electrochemical testing of lithium-sulfur batteries:
[0083] The battery uses a 2032 battery casing, with S / HEA@HC / HCNB or S / HC / HCNB as the positive electrode, lithium foil as the negative electrode, and commercial porous polypropylene (Celgard 2400) as the separator. The battery is assembled in an argon-filled glove box. The positive electrode loading of the lithium-sulfur battery is 1.0 mg / cm³. -2 The electrolyte used was a DOL / DME (v / v, 1:1) mixed solution containing 1.0 M lithium bis(trifluoromethane)sulfonylimide (LiTFSI) and 0.2 M LiNO3. The electrolyte-to-sulfur ratio (E / S) was controlled at 10 μmg. -1 about.
[0084] Constant current charge-discharge (GCD) tests were performed on the LANCT battery testing system at different rates within a voltage range of 1.7 to 2.8 V at room temperature. Cyclic voltammetry (CV) measurements were performed between 1.7 and 2.8 V using a VMP3 multichannel electrochemical workstation (BioLogic, France).
[0085] Figure 11 The cycle characteristics of lithium-sulfur batteries under 0.1C conditions;
[0086] Figure 12 The cycle characteristics of lithium-sulfur batteries under 1C conditions;
[0087] Figure 13 High sulfur loading (9 mg / cm³) -2 Cycle characteristics of lithium-sulfur batteries at 0.1C;
[0088] from Figure 11-13 It can be seen that the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1, when used in lithium-sulfur batteries with positive electrode hosts, exhibit a performance of 1290.2 mAh g⁻¹ at 0.1C. -1 Initial capacity and excellent cycling stability. After 3000 cycles at 1C, the average capacity decay rate per cycle is only 0.03%. Furthermore, at 9 mg / cm³... -2 Under high sulfur loading, the initial areal capacity can reach 10.2 mAh / cm³. -2 The areal capacity remains at 8.5 mAh cm⁻¹ during 35 cycles. -2 above.
[0089] Therefore, it is demonstrated that the high-entropy intermetallic compound nanomaterials distributed on the surface of hollow carbon spheres prepared in Example 1 can effectively catalyze the multi-step conversion of sulfur cathode, thereby improving the cycle performance of lithium-sulfur batteries.
[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing high-entropy intermetallic compound nanomaterials, characterized in that... A high-entropy intermetallic compound nanomaterial is in the form of particles and is composed of five elements: Fe, Co, Ni, Pt, and Cu. It has a PtCu3 phase structure, in which Pt occupies the vertex position of the face-centered cubic structure, while Fe, Co, Ni, and Cu randomly occupy the face center position of the face-centered cubic structure. The preparation method is specifically carried out according to the following steps: I. Preparation of hollow carbon spheres: ① Mix anhydrous ethanol, deionized water and NH3·H2O, stir for a period of time, then add tetraethyl silicate dropwise, and finally add a mixture of resorcinol and formaldehyde to obtain solution A; ② Stir solution A continuously for a period of time, then transfer it to a high-pressure reactor lined with Teflon for hydrothermal reaction. After the reaction is completed, centrifuge and dry to obtain product A. Calcine product A in N2 atmosphere at a temperature of 750℃~850℃ for a period of time to obtain product B. Immerse product B in NaOH solution for a period of time to remove SiO2 spheres and obtain hollow carbon spheres. II. In-situ synthesis of high-entropy intermetallic compound nanomaterials on hollow carbon spheres: H₂PtCl₆·6H₂O, FeCl₂·4H₂O, NiCl₂·6H₂O, CoCl₂·6H₂O, and CuCl₂·2H₂O were added to deionized water and sonicated to form a homogeneous solution, resulting in a mixed solution. Hollow carbon spheres were added to the mixed solution, stirred for a period of time, and then evaporated to dryness using a rotary evaporator. The solution was then transferred to a tube furnace and heated for a period of time in a mixed atmosphere of H₂ and Ar at a temperature of 950℃~1000℃ to obtain high-entropy intermetallic compound nanomaterials uniformly distributed on the surface of the hollow carbon spheres.
2. The method for preparing a high-entropy intermetallic compound nanomaterial according to claim 1, characterized in that... The high-entropy intermetallic compound nanomaterial is composed of five elements: Fe, Co, Ni, Pt, and Cu, with each element having a mass fraction of 5% to 35%; the particle size of the high-entropy intermetallic compound nanomaterial is less than 10 nm.
3. The method for preparing a high-entropy intermetallic compound nanomaterial according to claim 1, characterized in that... The volume ratio of anhydrous ethanol, deionized water, NH3·H2O, and tetraethyl silicate in step 1① is (60mL~80mL):(5mL~15mL):(2mL~4mL):(2mL~3mL); the mass ratio of resorcinol to formaldehyde in the mixture of resorcinol and formaldehyde in step 1① is (0.3g~0.5g):(0.4mL~0.7mL).
4. The method for preparing a high-entropy intermetallic compound nanomaterial according to claim 1, characterized in that... The volume ratio of anhydrous ethanol to methanol in the mixture of resorcinol and formaldehyde in step 1① is (60mL~80mL):(0.4mL~0.7mL); the stirring temperature in step 1① is 30℃~40℃, and the stirring time is 20min~40min; the rate at which tetraethyl silicate is added dropwise in step 1① is 20 drops / min~40 drops / min.
5. The method for preparing a high-entropy intermetallic compound nanomaterial according to claim 1, characterized in that... In step 1②, solution A is continuously stirred at 30°C~40°C for 20h~24h; the hydrothermal reaction temperature in step 1② is 90°C~110°C, and the hydrothermal reaction time is 20h~24h.
6. The method for preparing a high-entropy intermetallic compound nanomaterial according to claim 1, characterized in that... The calcination time in step 1② is 1h~3h; the concentration of NaOH solution in step 1② is 2mol / L~3mol / L; the time for immersing product B in NaOH solution in step 1② is 3d~5d.
7. The method for preparing a high-entropy intermetallic compound nanomaterial according to claim 1, characterized in that... The high-entropy intermetallic compound nanomaterials mentioned in step two are composed of five elements: Fe, Co, Ni, Pt, and Cu, with each element having a mass fraction of 5% to 35%. The mass-volume ratio of H2PtCl6·6H2O, hollow carbon spheres, and deionized water mentioned in step two is (30mg to 50mg):(90mg to 100mg):100mL.
8. The method for preparing a high-entropy intermetallic compound nanomaterial according to claim 1, characterized in that... In step two, hollow carbon spheres are added to the mixed solution and stirred for 10-12 hours; in step two, the volume ratio of H2 to Ar in the mixed atmosphere is 5:100; in step two, the heating time in the mixed atmosphere of H2 and Ar at a temperature of 950℃-1000℃ is 1-3 hours.
9. The application of the high-entropy intermetallic compound nanomaterials prepared by the preparation method according to claim 1, characterized in that... High-entropy intermetallic compound nanomaterials are used as positive electrode catalysts in lithium-sulfur batteries.