A high-entropy alloy type FeS2 / C composite material, a preparation method and application thereof

Abstract

The application discloses a high-entropy alloy type FeS2@C composite material and a preparation method and application thereof, and belongs to the technical field of entropy alloy material preparation. The high-entropy alloy type FeS2 / C composite material is prepared from a raw material of an iron source, metal soluble salt, sublimed sulfur and a carbon material dispersion liquid, and then ethylene glycol solution is added, stirring is performed until dissolution, and hydrothermal reaction is performed at 180-200 DEG C. The high-entropy alloy type FeS2 / C composite material is prepared by the solvent thermal reaction of the application, the synthesized FeS2 / C material is uniform in particle size, small in particle size and good in dispersibility. The application improves the utilization rate of reactants, shortens the reaction time, improves the yield, and has the advantages of simple operation, low requirement on reaction equipment, mild conditions, mass production and the like. The high-entropy alloy type FeS2@C composite material with excellent performance is prepared by a simple and efficient preparation method.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy material preparation technology, specifically to a high-entropy alloy FeS2 / C composite material, its preparation method, and its application. Background Technology

[0002] Electrochemical energy storage and conversion batteries have become one of the most important devices in people's daily lives. Rechargeable battery systems, as a clean energy technology, are gradually replacing traditional fossil fuels in the energy market and have gained a place in both stationary and mobile energy storage products. Among these alternative energy technologies, metal-ion batteries are widely used due to their high energy density and long lifespan. With continuous technological development, long lifespan and high safety are becoming increasingly important in battery design. Metal-polysulfide batteries, as a conversion reaction system with high theoretical energy density and low cost, have attracted widespread attention.

[0003] Pyrite (FeS2) is characterized by its high theoretical specific capacity (890 mA hg). -1 FeS2 is considered a promising cathode material due to its stable structure, safety, and lack of pollution. To date, numerous methods have been developed for synthesizing FeS2, including sol-gel methods, solvothermal methods, microwave irradiation, and solid-state reactions. These methods typically involve toxic reaction sources or organic solvents, and the FeS2 products often have end-capping reagents on their surfaces, affecting ion transport and cation exchange processes. Furthermore, the low intrinsic conductivity of FeS2 and its volume shrinkage / expansion during cycling severely damage its structure, leading to poor stability and rate performance during cycling, hindering its practical application. To improve the cycling performance of FeS2, researchers have modified FeS2 cathode materials using methods such as morphology design, voltage control, and electrolyte optimization. However, from a materials design perspective, these approaches do not fundamentally improve the bulk stability of the material. Therefore, this invention provides a high-entropy alloy-type FeS2 / C composite material, its preparation method, and its applications. Summary of the Invention

[0004] This invention provides a high-entropy alloy-type FeS2 / C composite material, its preparation method, and its application. On the one hand, it avoids the problems of existing FeS2 material synthesis using toxic reaction sources and organic reagents, and the resulting products having end-capping reagents on their surfaces, which affect ion transport and cation exchange processes. On the other hand, it solves the technical problems of existing FeS2 materials having low conductivity as positive electrode materials, and the volume shrinkage / expansion during cycling causing severe structural damage to the material, resulting in poor stability and rate performance during cycling. At the same time, it provides a pollution-free, high-yield, and low-energy-consumption method for preparing high-entropy alloy-type FeS2 / C composite materials.

[0005] The first objective of this invention is to provide a method for preparing a high-entropy alloy-type FeS2 / C composite material, comprising the following steps:

[0006] A soluble iron source, three or four soluble metal salts, and sublimed sulfur are added to a carbon material dispersion, followed by the addition of ethylene glycol solution. The mixture is stirred and dissolved, and then subjected to a hydrothermal reaction at 180–200 °C to load the carbon material onto FeS2. This process yields a composite material with an entropy value ≥1R, thus obtaining the FeS2 precursor. After centrifugation and washing, the crude FeS2 product is obtained. This product is then dried and ground to obtain a high-entropy alloy-type FeS2 / C composite material.

[0007] In a preferred embodiment, the molar ratio of the soluble iron source, three or four soluble metal salts, and sublimed sulfur is 1:0.17 to 4:5.

[0008] In a preferred embodiment, the carbon material accounts for 10% to 20% of the mass of the high-entropy alloy-type FeS2 / C composite material.

[0009] In a preferred embodiment, the carbon material dispersion is a dispersion of carbon material in N,N-dimethylformamide, wherein the volume ratio of N,N-dimethylformamide to ethylene glycol solution is 1:1 to 3.

[0010] In a preferred embodiment, the hydrothermal reaction time is 12 to 24 hours.

[0011] In a preferred embodiment, the three or four metal-soluble salts are selected from three or four of cobalt salts, copper salts, manganese salts, nickel salts, zinc salts, molybdenum salts, tin salts, and niobium salts; the metal-soluble salts may be selected from CoSO4·7H2O, CuSO4·5H2O, MnSO4·H2O, NiSO4·6H2O, ZnSO4·7H2O, CoCl2·6H2O, CuCl2·2H2O, NiCl2·6H2O, (NH4)2MoO4, SnCl2, MnCl2·4H2O, C 10 H5NbO 20 .

[0012] In a preferred embodiment, the carbon material is carbon nanotubes, bio-based carbon, graphene oxide, or N,S dual-doped carbon.

[0013] In a preferred embodiment, the iron source is FeCl2·4H2O, Fe(NO3)3, Fe(OH)(CH3COO)2 or FeSO4.

[0014] The second objective of this invention is to provide a high-entropy alloy-type FeS2 / C composite material prepared by the above-described preparation method.

[0015] The third objective of this invention is to provide an application of the above-mentioned high-entropy alloy FeS2 / C composite material in the preparation of positive electrode materials. Specifically, the high-entropy alloy FeS2 / C composite material is mixed with acetylene black and PVDF binder at a mass ratio of 8:1:1 and ground for 10 min. 0.5 mL of nitrogen-methylpyrrolidone is added dropwise to obtain a slurry. The slurry is coated on a 15 μm copper foil and dried at 60 °C for 12 h to obtain an entropy alloy FeS2 / C positive electrode.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] (1) This invention provides a high-entropy alloy-type FeS2 / C composite material, its preparation method, and its application. Using an iron source, a soluble metal salt, sublimed sulfur, and a carbon material dispersion as raw materials, ethylene glycol solution is added, stirred until dissolved, and subjected to a hydrothermal reaction at 180–200°C to obtain a FeS2 precursor. After centrifugation and washing, a crude FeS2 product is obtained, which is then dried and ground to obtain the high-entropy alloy-type FeS2 / C composite material. The solvothermal reaction method of this invention for preparing the high-entropy alloy-type FeS2 / C composite material ensures system uniformity during the reaction process, resulting in FeS2 / C materials with uniform particle size, small particle size, and good dispersibility. This invention significantly improves the utilization rate of reactants, shortens the reaction time, increases the yield, and has advantages such as simple operation, low requirements for reaction equipment, mild conditions, and the ability to produce in large quantities. A high-entropy alloy-type FeS2@C composite material with excellent performance was prepared through a simple and efficient preparation method.

[0018] (2) This invention uses iron source, soluble metal salt, sublimed sulfur, and carbon materials as raw materials to prepare a highly disordered high-entropy alloy solid solution. By increasing the mixing entropy of the constituent elements and maximizing the mixing entropy as much as possible, the FeS2 electrode structure is stabilized, the volume expansion of the FeS2 electrode material is suppressed, and its cycle performance is improved. Example 6 of this invention prepares a high-entropy alloy Fe... 0.2 Co 0.2 Cu 0.2 Ni 0.2 Mo 0.2 The entropy of S2 / C composite materials can reach 1.6094R. The rich and flexible compositional design of high-entropy alloys reduces dependence on single elements and allows for the tuning of the electronic structure of entropy alloy-type FeS2 electrode materials, particularly the Fermi level related to electrode potential. The synergistic effect of multiple elements and the inherently complex surface of high-entropy alloys can provide near-continuous adsorption energy, making them ideal for multi-step tandem reaction systems of sulfide FeS2@C electrodes. The highly disordered and distorted lattice of high-entropy alloys can generate numerous defects in FeS2 electrode materials, which is beneficial for electron and ion migration.

[0019] (3) The high-entropy alloy FeS2@C composite material prepared in this invention is used to make a positive electrode material, and at 5A g -1 At the rate current, the rate capacitance is 588.4 mA hg -1 At 0.5A g -1 After 500 charge-discharge cycles at the current density, the discharge capacity remained at 576.8 mA hg. -1 The capacity retention rate was 81.7%.

[0020] (7) The preparation method of the high-entropy alloy FeS2@C composite material provided by the present invention is simple, environmentally friendly, has high yield, low energy consumption and wide applicability. Attached Figure Description

[0021] Figure 1 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 XRD pattern of S2 / C;

[0022] Figure 2 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 Elemental distribution diagram of S2 / C;

[0023] Figure 3 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 Transmission electron micrograph of S2 / C;

[0024] Figure 4 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C rate performance chart;

[0025] Figure 5 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C at 500mA g -1 Charge-discharge cycle diagram at current density. Detailed Implementation

[0026] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the invention. Unless otherwise specified, the following test methods and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0027] Based on the following three technical problems concerning FeS2 materials raised in the background of this invention: First, existing methods for synthesizing FeS2, such as the sol-gel method, solvothermal method, microwave radiation, and solid-state reaction, involve toxic reaction sources or organic solvents, and the FeS2 products usually have end-capping reagents on their surfaces, affecting ion transport and cation exchange processes. Second, the low intrinsic conductivity of FeS2 materials and the volume shrinkage / expansion during cycling severely damage the material's structure, resulting in poor stability and rate performance during cycling, hindering its practical application. Third, modifying FeS2 cathode materials using methods such as morphology design, voltage control, and electrolyte optimization cannot fundamentally improve the bulk stability of the material.

[0028] To address the aforementioned technical problems, this invention adds an iron source, a metal-soluble salt, and sublimed sulfur to a dispersion of carbon materials (carbon nanotubes, bio-based carbon, graphene oxide, or N,S dual-doped carbon), then adds an ethylene glycol solution, stirs until dissolved, and performs a hydrothermal reaction at 180–200°C for 12–24 hours to obtain an FeS2 precursor. After centrifugation and washing, a crude FeS2 product is obtained, which is then dried and ground to obtain a high-entropy alloy-type FeS2 / C composite material.

[0029] The structural and phase stability of a material depends on its entropy (ΔS) and enthalpy (ΔH), as shown in equation (1) according to the Gibbs free energy (ΔG) formula:

[0030] ΔG mix =ΔH mix -TΔS mix (1)

[0031] Where ΔS is the total entropy change, including configurational and dynamical contributions. The Gibbs free energy of a stable system is always the lowest. According to equation (1), it can be deduced that increasing the configurational entropy can increase the total entropy and entropy value, thereby obtaining a lower Gibbs free energy, which is beneficial to improving the structural stability of the material. Therefore, structural stability can be adjusted by manipulating the configurational entropy of the material. This entropy-mediated structural stability opens up a new type of high-performance electrode material that modifies and optimizes the structure.

[0032] Entropy-modified materials are generally classified into low entropy (S≤0.69R), medium entropy (S=0.69R~1R), and high entropy (S≥1R). Here, R is the gas constant, 8.314 J / (mol·K). The configuration entropy (ΔSconfig) is calculated using equation (2):

[0033]

[0034] It should be noted that the molar ratio of the iron source, the soluble metal salt, and sublimed sulfur is 1:0.17 to 4:5. The iron source is FeCl2·4H2O, Fe(NO3)3, Fe(OH)(CH3COO)2, or FeSO4. Increasing or decreasing its amount outside the given molar ratio range will cause the synthesized FeS2 / C composite material to fail to reach the expected design entropy value, and the molar ratio between the soluble metal salt and sublimed sulfur will not reach 1:2. When the amount of sublimed sulfur exceeds the given molar ratio, unreacted sulfur impurities are introduced into the target product of the system; when the amount of sublimed sulfur is below the given molar ratio, byproducts will be introduced into the final product.

[0035] To ensure the electrochemical performance of the composite material and thus improve battery performance, the carbon material accounts for 10% to 20% of the mass of the high-entropy alloy FeS2 / C composite material. When the carbon content is less than 10%, the electrochemical performance is not significantly improved after FeS2 and C materials are combined. When the carbon content is greater than 20%, the introduction of too much carbon material into the system causes a severe decrease in the energy density of the cathode material when it is used in the battery.

[0036] To further ensure the electrochemical performance of the composite material, the carbon material dispersion is a dispersion of carbon material in N,N-dimethylformamide, with a volume ratio of N,N-dimethylformamide to ethylene glycol solution of 1:1 to 3. The boiling points of N,N-dimethylformamide and ethylene glycol are 152.8℃ and 197.3℃, respectively. Mixing them ensures the safety of the hydrothermal reaction within the 180–200℃ range. Furthermore, electrochemical performance tests show that the performance is optimal when the volume ratio falls within this range.

[0037] According to the high-entropy design rule, in order to achieve the expected design entropy value for the composite material, the three or four soluble metal salts are selected from three or four of the following: cobalt salt, copper salt, manganese salt, nickel salt, zinc salt, molybdenum salt, tin salt, and niobium salt. The soluble metal salts can be selected from CoSO4·7H2O, CuSO4·5H2O, MnSO4·H2O, NiSO4·6H2O, ZnSO4·7H2O, CoCl2·6H2O, CuCl2·2H2O, NiCl2·6H2O, (NH4)2MoO4, SnCl2, MnCl2·4H2O, C... 10 H5NbO 20 .

[0038] The effects are illustrated below through specific examples and comparative models.

[0039] Example 1 (Fe) 0.85 Co 0.05 Cu 0.05 Ni 0.05 S2 / C)

[0040] A high-entropy alloy type Fe 0.85 Co 0.05 Cu 0.05 Ni 0.05 The preparation method of S2 / C composite material includes the following steps:

[0041] 0.0965 g of N,S dual-doped carbon was weighed and placed in a beaker. 20 mL of N,N-dimethylformamide (DMF) was added, and the mixture was sonicated for 15 min to obtain solution A. Solution A was transferred to an inner liner. Then, 1.352 g of FeCl₂·4H₂O, 1.090 g of sublimed sulfur, 0.112 g of CoSO₄·7H₂O, 0.099 g of CuSO₄·5H₂O, and 0.105 g of NiSO₄·6H₂O were weighed and mixed into the inner liner. Finally, 40 mL of ethylene glycol was added, and the mixture was stirred on a magnetic stirrer until completely dissolved. After stirring magnetically at room temperature for 2 hours, the mixture was transferred to a high-pressure reactor and placed in a forced-air drying oven at 180 °C for 12 h. After the reactor cooled to room temperature, it was opened, yielding a black precipitate. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then placed in a forced-air drying oven at 80 °C until completely dried. The dried sample required further grinding to obtain the target product Fe. 0.85 Co 0.05 Cu 0.05 Ni 0.05 S2 / C.

[0042] Example 2 (Fe) 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C)

[0043] A high-entropy alloy type Fe 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 The preparation method of S2 / C composite material includes the following steps:

[0044] 0.1007 g of carbon nanotubes were weighed and placed in a beaker. 20 mL of N,N-dimethylformamide (DMF) was added, and the mixture was sonicated for 15 min to obtain solution A. Solution A was transferred to an inner liner. Then, 1.272 g of FeCl2·4H2O, 1.026 g of sublimed sulfur, 0.112 g of CoSO4·7H2O, 0.099 g of CuSO4·5H2O, 0.105 g of NiSO4·6H2O, and 0.078 g of (NH4)2MoO4 were weighed and mixed together and added to the inner liner. Finally, 40 mL of ethylene glycol was added, and the mixture was stirred on a magnetic stirrer until completely dissolved. After stirring magnetically at room temperature for 2 hours, the mixture was transferred to a high-pressure reactor and placed in a forced-air drying oven at 180 °C for 12 h. After the reactor cooled to room temperature, it was opened, and a black precipitate was obtained. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then placed in a forced-air drying oven at 80 °C until completely dry. The dried sample needs to be further ground to obtain the target product Fe. 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C.

[0045] Example 3 (Fe) 0.8 Sn 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C)

[0046] A high-entropy alloy type Fe 0.8 Sn 0.05 Cu 0.05 Ni 0.05 Mo 0.05 The preparation method of S2 / C composite material includes the following steps:

[0047] 0.1083 g of bio-based carbon was weighed and placed in a beaker. 20 mL of N,N-dimethylformamide (DMF) was added, and the mixture was sonicated for 15 min to obtain solution A. Solution A was transferred to an inner liner. Then, 1.272 g of FeCl2·4H2O, 1.026 g of sublimed sulfur, 0.076 g of SnCl2, 0.099 g of CuSO4·5H2O, 0.105 g of NiSO4·6H2O, and 0.078 g of (NH4)2MoO4 were weighed and mixed together and added to the inner liner. Finally, 40 mL of ethylene glycol was added, and the mixture was stirred on a magnetic stirrer until completely dissolved. After stirring magnetically at room temperature for 2 hours, the mixture was transferred to a high-pressure reactor and placed in a forced-air drying oven at 180 °C for 12 h. After the reactor cooled to room temperature, it was opened, yielding a black precipitate. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then placed in a forced-air drying oven at 80 °C until completely dry. The dried sample needs to be further ground to obtain the target product Fe.0.8 Sn 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C.

[0048] Example 4 (Fe) 0.6 Co 0.1 Cu 0.1 Ni 0.1 Mo 0.1 S2 / C)

[0049] A high-entropy alloy type Fe 0.6 Co 0.1 Cu 0.1 Ni 0.1 Mo 0.1 The preparation method of S2 / C composite material includes the following steps:

[0050] 0.1204 g of carbon nanotubes were weighed and placed in a beaker. 20 mL of N,N-dimethylformamide (DMF) was added, and the mixture was sonicated for 15 min to obtain solution A. Solution A was transferred to an inner liner. Then, 0.954 g of FeCl2·4H2O, 1.026 g of sublimed sulfur, 0.225 g of CoSO4·7H2O, 0.200 g of CuSO4·5H2O, 0.210 g of NiSO4·6H2O, and 0.157 g of (NH4)2MoO4 were weighed and mixed together and added to the inner liner. Finally, 40 mL of ethylene glycol was added, and the mixture was stirred on a magnetic stirrer until completely dissolved. After stirring magnetically at room temperature for 2 hours, the mixture was transferred to a high-pressure reactor and placed in a forced-air drying oven at 180 °C for 12 h. After the reactor cooled to room temperature, it was opened, and a black precipitate was obtained. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then placed in a forced-air drying oven at 80 °C until completely dry. The dried sample needs to be further ground to obtain the target product Fe. 0.6 Co 0.1 Cu 0.1 Ni 0.1 Mo 0.1 S2 / C.

[0051] Example 5 (Fe) 0.4 Co 0.15 Cu 0.15 Ni 0.15 Mo 0.15 S2 / C)

[0052] A high-entropy alloy type Fe 0.4 Co 0.15 Cu 0.15 Ni 0.15 Mo 0.15 The preparation method of S2 / C composite material includes the following steps:

[0053] 0.1551 g of N,S dual-doped carbon was weighed and placed in a beaker. 20 mL of N,N-dimethylformamide (DMF) was added, and the mixture was sonicated for 15 min to obtain solution A. Solution A was transferred to an inner liner. Then, 0.636 g of FeCl₂·4H₂O, 1.026 g of sublimed sulfur, 0.337 g of CoSO₄·7H₂O, 0.300 g of CuSO₄·5H₂O, 0.315 g of NiSO₄·6H₂O, and 0.235 g of (NH₄)₂MoO₄ were weighed and mixed together in the inner liner. Finally, 40 mL of ethylene glycol was added, and the mixture was stirred on a magnetic stirrer until completely dissolved. After stirring magnetically at room temperature for 2 hours, the mixture was transferred to a high-pressure reactor and placed in a forced-air drying oven at 180 °C for 12 h. After the reactor cooled to room temperature, it was opened, yielding a black precipitate. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then placed in a forced-air drying oven at 80 °C until completely dry. The dried sample needs to be further ground to obtain the target product Fe. 0.4 Co 0.15 Cu 0.15 Ni 0.15 Mo 0.15 S2 / C.

[0054] Example 6 (Fe) 0.2 Co 0.2 Cu 0.2 Ni 0.2 Mo 0.2 S2 / C)

[0055] A high-entropy alloy type Fe 0.2 Co 0.2 Cu 0.2 Ni 0.2 Mo 0.2 The preparation method of S2 / C composite material includes the following steps:

[0056] 0.2048 g of bio-based carbon was weighed and placed in a beaker. 20 mL of N,N-dimethylformamide (DMF) was added, and the mixture was sonicated for 15 min to obtain solution A. Solution A was transferred to an inner liner. Then, 0.318 g of Cl₂·4H₂O, 1.026 g of sublimed sulfur, 0.450 g of CoSO₄·7H₂O, 0.400 g of CuSO₄·5H₂O, 0.421 g of NiSO₄·6H₂O, and 0.314 g of (NH₄)₂MoO₄ were weighed and mixed together and added to the inner liner. Finally, 40 mL of ethylene glycol was added, and the mixture was stirred on a magnetic stirrer until completely dissolved. After stirring magnetically at room temperature for 2 hours, the mixture was transferred to a high-pressure reactor and placed in a forced-air drying oven at 180 °C for 12 h. After the reactor cooled to room temperature, it was opened, yielding a black precipitate. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then placed in a forced-air drying oven at 80 °C until completely dry. The dried sample needs to be further ground to obtain the target product Fe. 0.2 Co 0.2 Cu 0.2 Ni 0.2 Mo 0.2 S2 / C.

[0057] Example 7 (Fe) 0.52 Co 0.12 Mn 0.12 Mo 0.12 Ni 0.12 S2 / C)

[0058] A high-entropy alloy type Fe 0.52 Co 0.12 Mn 0.12 Mo 0.12 Ni 0.12 The preparation method of S2 / C composite material includes the following steps:

[0059] 0.1003 g of N,S dual-doped carbon was weighed and placed in a beaker. 20 mL of N,N-dimethylformamide (DMF) was added, and the mixture was sonicated for 15 min to obtain solution A. Solution A was transferred to an inner liner. Then, 0.827 g of FeCl2·4H2O, 1.026 g of sublimed sulfur, 0.270 g of CoSO4·7H2O, 0.162 g of MnSO4·H2O, 0.252 g of NiSO4·6H2O, and 0.188 g of (NH4)2MoO4 were weighed and mixed together in the inner liner. Finally, 40 mL of ethylene glycol was added, and the mixture was stirred on a magnetic stirrer until completely dissolved. After stirring magnetically at room temperature for 2 hours, the mixture was transferred to a high-pressure reactor and placed in a forced-air drying oven at 180 °C for 12 h. After the reactor cooled to room temperature, it was opened, yielding a black precipitate. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then placed in a forced-air drying oven at 80 °C until completely dry. The dried sample needs to be further ground to obtain the target product Fe. 0.5 2Co 0.12 Mn 0.12 Mo 0.12 Ni 0.12 S2 / C.

[0060] Example 8 (Fe) 0.52 Co 0.12 Mn 0.12 Mo 0.12 Nb 0.12 S2 / C)

[0061] A high-entropy alloy type Fe 0.52 Co 0.12 Mn 0.12 Mo 0.12 Nb 0.12 The preparation method of S2 / C composite material includes the following steps:

[0062] Weigh 0.1036 g of carbon nanotubes and place them in a beaker. Add 20 mL of N,N-dimethylformamide (DMF) and sonicate for 15 min to obtain solution A. Transfer solution A to the inner liner. Then weigh 0.827 g of FeCl2·4H2O, 1.026 g of sublimed sulfur, 0.270 g of CoSO4·7H2O, 0.162 g of MnSO4·H2O, and 0.517 g of C. 10 H5NbO 20The mixture was placed in the inner liner with 0.188 g of (NH4)2MoO4, and then 40 mL of ethylene glycol was added. The mixture was then stirred on a magnetic stirrer until completely dissolved. After stirring magnetically for 2 hours at room temperature, the mixture was transferred to a high-pressure reactor and placed in a drying oven at 180°C for 12 hours. After the reactor cooled to room temperature, it was opened, yielding a black precipitate. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then dried completely in a drying oven at 80°C. The dried sample required further grinding to obtain the target product Fe. 0.52 Co 0.12 Mn 0.12 Mo 0.12 Nb 0.12 S2 / C.

[0063] Example 9 (Fe) 0.52 Co 0.12 Mn 0.12 Mo 0.12 Sn 0.12 S2 / C)

[0064] A high-entropy alloy type Fe 0.52 Co 0.12 Mn 0.12 Mo 0.12 Sn 0.12 The preparation method of S2 / C composite material includes the following steps:

[0065] Weigh 0.106 g of N,S dual-doped carbon into a beaker, add 20 mL of N,N-dimethylformamide (DMF), and sonicate for 15 min to obtain solution A. Transfer solution A to the inner liner, then weigh 0.827 g FeCl2·4H2O, 1.026 g sublimed sulfur, 0.270 g CoSO4·7H2O, 0.162 g MnSO4·H2O, and 0.517 g C. 10 H5NbO 20 Mix 0.182 g of SnCl2 with the inner container, then add 40 mL of ethylene glycol and stir on a magnetic stirrer until completely dissolved. Stir magnetically for 2 hours at room temperature, then transfer to a high-pressure reactor and place in a drying oven at 180°C for 12 hours. After the reactor cools to room temperature, open it to obtain a black precipitate. Wash the precipitate three times each with deionized water and anhydrous ethanol, and then place it in an 80°C drying oven until completely dry. The dried sample needs further grinding to obtain the target product Fe. 0.52 Co 0.12 Mn 0.12 Mo 0.12 Sn 0.12 S2 / C.

[0066] Example 10 (Fe)0.52 Co 0.12 Zn 0.12 Mo 0.12 Sn 0.12 S2 / C)

[0067] A high-entropy alloy type Fe 0.52 Co 0.12 Zn 0.12 Mo 0.12 Sn 0.12 The preparation method of S2 / C composite material includes the following steps:

[0068] Weigh 0.107 g of bio-based carbon and place it in a beaker. Add 20 mL of N,N-dimethylformamide (DMF) and sonicate for 15 min to obtain solution A. Transfer solution A to the inner liner. Then weigh 0.827 g FeCl2·4H2O, 1.026 g sublimed sulfur, 0.270 g CoSO4·7H2O, 0.276 g ZnSO4·7H2O, 0.188 g (NH4)2MoO4, and 0.182 g SnCl2 and mix them into the inner liner. Finally, add 40 mL of ethylene glycol and place the mixture on a magnetic stirrer until completely dissolved. Stir magnetically at room temperature for 2 hours, then transfer to a high-pressure reactor and place it in a forced-air drying oven at 180 °C for 12 h. After the reactor cools to room temperature, open it to obtain a black precipitate. Wash the precipitate three times each with deionized water and anhydrous ethanol, and place it in a forced-air drying oven at 80 °C until completely dry. The dried sample needs to be further ground to obtain the target product Fe. 0.52 Co 0.12 Mn 0.12 Mo 0.12 Sn 0.12 S2 / C.

[0069] Example 11 (Fe) 0.52 Zn 0.12 Mn 0.12 Mo 0.12 Sn 0.12 S2 / C)

[0070] A high-entropy alloy type Fe 0.52 Zn 0.12 Mn 0.12 Mo 0.12 Sn 0.12 The preparation method of S2 / C composite material includes the following steps:

[0071] 0.107 g of carbon nanotubes were weighed and placed in a beaker. 20 mL of N,N-dimethylformamide (DMF) was added and sonicated for 15 min to obtain solution A. Solution A was transferred to the inner liner. Then, 0.827 g of FeCl2·4H2O, 1.026 g of sublimed sulfur, 0.276 g of ZnSO4·7H2O, 0.162 g of MnSO4·H2O, 0.188 g of (NH4)2MoO4, and 0.182 g of SnCl2 were weighed and mixed and placed in the inner liner. Finally, 40 mL of ethylene glycol was added and the mixture was placed on a magnetic stirrer and stirred until completely dissolved. After stirring magnetically at room temperature for 2 hours, the mixture was transferred to a high-pressure reactor and placed in a forced-air drying oven at 180 °C for 12 h. After the reactor cooled to room temperature, it was opened to obtain a black precipitate. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then placed in an 80°C forced-air drying oven until completely dry. The dried sample required further grinding to obtain the target product Fe. 0.52 Zn 0.12 Mn 0.12 Mo 0.12 Sn 0.12 S2 / C.

[0072] To further illustrate the technical effects of the present invention, comparative examples are also provided, as follows:

[0073] Comparative Example 1

[0074] FeS2 / C material was prepared using a solvothermal method: 1.590 g of FeCl2·4H2O and 1.282 g of sublimed sulfur were weighed and mixed in an inner container. Finally, 40 mL of ethylene glycol and 20 mL of N,N-dimethylformamide were added, and the mixture was stirred on a magnetic stirrer until completely dissolved. After stirring magnetically at room temperature for 2 hours, the mixture was transferred to a high-pressure reactor and placed in a forced-air drying oven at 180 °C for 12 hours. After the reactor cooled to room temperature, it was opened, yielding a black precipitate. The precipitate was washed three times each with deionized water and anhydrous ethanol, and then placed in a forced-air drying oven at 80 °C until completely dried. The dried sample required further grinding to obtain the target product, FeS2 / CNT.

[0075] The target products prepared in Examples 1-11 and Comparative Example 1 of the present invention were respectively prepared into positive electrode materials. High-entropy alloy FeS2 / C composite material (or FeS2 / CNT) was mixed with acetylene black and PVDF binder at a mass ratio of 8:1:1 and ground for 10 min. 0.5 mL of N-methylpyrrolidone was added dropwise to obtain a slurry. The slurry was coated onto a 15 μm copper foil and dried at 60 °C for 12 h to obtain an entropy alloy FeS2 / C positive electrode. The performance of each was tested. Since the effects of Examples 1-11 are similar, only Example 2 is used as an example to illustrate the effect. The results are as follows: Figures 1-5 As shown.

[0076] Figure 1 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 XRD pattern of S2 / C; by Figure 1 It can be seen that the prepared sample is a single phase, belonging to the space group Pa-3(205). The diffraction peaks at 2θ of 28.5°, 33.1°, 37.2°, 40.7°, 47.5°, 56.3° and 64.3° correspond to the (111), (200), (210), (211), (220), (311) and (321) diffraction planes of FeS2 crystal with space group Pa-3(205), respectively, indicating that the prepared sample is a cubic FeS2 structure.

[0077] Figure 2 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 Elemental distribution diagram of S2 / C; by Figure 2 It can be known that: Fe 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 The C, S, Fe, Co, Cu, Ni, Mo and S elements on the S2 particles are uniformly distributed, and all the constituent elements have good overlap.

[0078] Figure 3 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 Transmission electron microscopy image of S2 / C; by Figure 3 It can be known that: Figure 3 (af) represents FeS2 / CNTs and Fe 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 HRTEM images of the S2 / C samples. The images show that the CNTs are uniformly distributed and well-bonded with the FeS2 particles. The prepared powders all exhibit micron-sized aggregated particles. Compared to FeS2 / CNTs, Fe... 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo0.05 The particle size of S2 / C material is reduced and the agglomeration is weakened. Figure 3 HR-TEM at (c,f) clearly shows FeS2 / CNTs and Fe 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C lattice fringes. Figure 3 -(c) HR-TEM shows the (023) crystal plane of FeS2 / CNTs with a lattice spacing of 0.333 nm. Figure 3 (f) HR-TEM showed Fe 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 The (321) crystal plane of S2 / C corresponds to a lattice spacing of 0.345 nm. The FFT image shows that entropy-stable Fe... 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C materials are single-phase compounds, not multiphase mixtures.

[0079] Figure 4 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C rate performance diagram; from Figure 4 As can be seen from the figure, the medium-entropy strategy significantly improves the rate performance of the prepared samples, especially for Fe. 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 S2 / C, at current densities of 500, 1000, 2000 and 5000 mA g -1 Below, 661.4, 637.2, 615.0, and 588.4 mA hg were provided respectively. -1 The discharge specific capacity. When the current density returns to 500 mA g -1 At that time, its discharge specific capacity can still recover to the initial value.

[0080] Figure 5 The Fe prepared in Example 2 of this invention 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05S2 / C at 500mA g -1 Charge-discharge cycle diagram at current density; by Figure 5 It can be known that: Fe 0.8 Co 0.05 Cu 0.05 Ni 0.05 Mo 0.05 The initial discharge capacity of S2 / C is 705.9 mA hg. -1 The discharge specific capacity after 500 cycles is 576.8 mA hg. -1 The capacity retention rate was 81.7%.

[0081] In summary, this invention improves the synthesis steps and equipment of the solvothermal reaction, employing a magnetic stirrer to ensure complete dissolution, thus guaranteeing system homogeneity during the reaction process. The synthesized FeS2 / C material exhibits uniform particle size, small particle size, and good dispersion. This invention significantly improves the utilization rate of reactants, shortens the reaction time, and increases the yield. Furthermore, it offers advantages such as simple operation, low equipment requirements, mild conditions, and suitability for large-scale production. A high-entropy alloy-type FeS2@C composite material with excellent performance was prepared using this simple and efficient method.

[0082] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a high-entropy alloy-type FeS2 / C composite cathode material, characterized in that, The specific steps are as follows: A soluble iron source, three or four soluble metal salts, and sublimed sulfur are added to a carbon material dispersion, followed by the addition of ethylene glycol solution to dissolve the material. The mixture is then subjected to a hydrothermal reaction at 180-200 °C to load the carbon material onto FeS2, thereby obtaining a composite material with an entropy value ≥1R. This results in a high-entropy alloy FeS2 / C composite cathode material. The molar ratio of the soluble iron source, the soluble metal salt, and sublimed sulfur is 1:0.17 to 4:5; based on the mass of the high-entropy alloy FeS2 / C composite material, the mass percentage of the carbon material is 10% to 20%. The three or four metal-soluble salts are selected from three or four of the following: cobalt salts, copper salts, manganese salts, nickel salts, zinc salts, molybdenum salts, tin salts, and niobium salts. The carbon material dispersion is a dispersion of carbon material in N,N-dimethylformamide, and the volume ratio of N,N-dimethylformamide to ethylene glycol solution is 1:1~3.

2. The preparation method according to claim 1, characterized in that, The hydrothermal reaction takes 12 to 24 hours.

3. The preparation method according to claim 1, characterized in that, The carbon material is carbon nanotube, bio-based carbon, graphene oxide, or N,S dual-doped carbon.

4. The preparation method according to claim 1, characterized in that, The iron source is FeCl2·4H2O, Fe(NO3)3, Fe(OH)(CH3COO)2 or FeSO4.

5. A high-entropy alloy FeS2 / C composite cathode material prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the high-entropy alloy FeS2 / C composite cathode material according to claim 5 in the preparation of cathode materials.

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