Preparation method and application of iron-based sulfide composite material

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a preparation method and application of an iron-based sulfide composite material. MIL-101 (Fe) and thiourea react under the hydrothermal condition and then react with graphene oxide, the iron-based sulfide composite material is obtained, and the iron-based sulfide composite material shows excellent electrochemical performance and serves as a battery negative electrode material. According to the preparation method, MIL-101 (Fe) is used as a precursor, the MIL-101 (Fe) is used as an ideal template, the MIL-101 (Fe) and low-toxicity thiourea are subjected to low-temperature hydro-thermal synthesis to form the double-phase metal sulfide with uniform morphology, the energy consumption is low, the process is mild and controllable, the high porosity and the regular morphology of the MIL-101 precursor are inherited and reserved to the greatest extent, and the preparation method has the advantages of simple process, high yield and high yield. And meanwhile, collaborative construction of heterojunction and pores is realized.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a method for preparing and applying an iron-based sulfide composite material. Background Technology

[0002] Currently, the ever-increasing demand for energy and the pressure to protect the environment are driving researchers to develop green and clean energy forms to gradually replace the currently dominant fossil fuels and build more environmentally friendly and safer energy storage and conversion systems. Lithium-ion batteries (LIBs) have achieved significant success in commercial energy storage devices. However, to meet the higher energy and power density requirements of electric vehicles and smart grids, further performance improvements are still needed. To date, significant progress has been made in improving the electrochemical performance of LIBs through innovative synthesis methods, multi-scale hierarchical structure design, and optimized matching of battery components. The rational selection of electrode materials is particularly crucial when implementing these strategies. As the main source of battery capacity, developing anode materials with high theoretical capacity and long-cycle stability is especially important.

[0003] FeS2, a metal sulfide, exhibits a high theoretical specific capacity (894 mAh / g) when used as an anode in lithium-ion batteries, but its poor conductivity and significant volume expansion (approximately 200%) severely affect its electrochemical stability. In contrast, Fe7S8, although having a lower theoretical capacity (663 mAh / g), possesses superior conductivity and a smaller volume change (approximately 160%), demonstrating better structural stability. Therefore, introducing the Fe7S8 phase into FeS2 is considered a promising strategy: Fe7S8 can act as an internal buffer matrix, mitigating the volume expansion of FeS2 during cycling and thus reducing material fragmentation; its good intrinsic conductivity also facilitates charge transport; simultaneously, the iron vacancies or surface functional groups in Fe7S8 can suppress the shuttle effect through chemical anchoring of polysulfides. Furthermore, since both FeS2 and Fe7S8 are predominantly Fe-S bonds, and the coordination environment of sulfur is similar, the atomic mismatch at their interface is small, which helps reduce defect formation. On the other hand, the Fe in Fe7S8... 2+ / Fe 3+ Mixed valence states and Fe in FeS2 2+Both phases can participate in redox reactions, further enhancing the overall capacity. In summary, constructing a FeS2 / Fe7S8 biphase metal sulfide system leverages the differences in reaction potential and mechanical properties between the two phases to achieve internal buffer volume changes and disperse stress concentration, thereby significantly improving the structural stability of the material. Metal-organic frameworks (MOFs), due to their tunable structure and abundant porosity, have been widely used as ideal precursors or templates for preparing nanostructured functional materials (including metal sulfides). Through pyrolysis and subsequent sulfidation treatment, MOFs can be transformed into metal sulfide nanomaterials with inherited porous structures. This structure not only facilitates sufficient electrolyte wetting but also provides buffer space to effectively accommodate volume changes during charge and discharge processes.

[0004] Most existing technologies directly utilize iron sources (such as ferric chloride) and sulfur sources (such as thiourea and L-cysteine) to hydrothermally generate iron sulfide; or first prepare iron oxide or iron hydroxide, then mix it with sulfur powder, and calcine it at high temperature in a tube furnace to prepare iron sulfide. The synthesis process is cumbersome, sulfur powder is flammable, and toxic and corrosive SO2 gas is generated at high temperatures. High-temperature energy consumption is high (usually 300-600℃ or even higher), and the pore structure is difficult to control. Summary of the Invention

[0005] This invention uses MIL-101 (Fe) as a precursor, taking advantage of its high iron content and stable and regular structure as an ideal template, to hydrothermally synthesize a uniformly morphological biphase metal sulfide FeS2 / Fe7S8-x (x=200, 220, 240) with low toxicity thiourea. It is further ultrasonically composited with graphene oxide (GO) with high specific surface area and good conductivity to obtain a FeS2 / Fe7S8-x@GO composite material with a three-dimensional conductive network. The material exhibits excellent electrochemical performance, and its synthesis process is simple, energy consumption is low, and the pore structure is easy to control.

[0006] The preparation method of the iron-based sulfide composite material of the present invention mainly involves reacting MIL-101 (Fe) and thiourea under hydrothermal conditions, and then reacting them with graphene oxide.

[0007] The specific steps are as follows: (1) Dissolve MIL-101 (Fe) and thiourea separately in deionized water. After they are fully dissolved, mix them together and continue stirring to obtain a mixed solution. (2) Transfer the mixed solution to a high-pressure reactor, seal it and react it at 200-240℃. After the reaction is completed, centrifuge, wash and dry the mixture to obtain a biphase metal sulfide sample. (3) Graphene oxide was ultrasonically dispersed in deionized water to obtain a uniform graphene oxide dispersion; the biphase metal sulfide sample was ultrasonically dispersed in deionized water to obtain a sample dispersion. (4) Mix the sample dispersion with the graphene oxide dispersion, stir ultrasonically, centrifuge and dry to obtain iron-based sulfide composite material.

[0008] In this invention, MIL-101(Fe) has the characteristics of high iron content, high stability and high regularity, making it an ideal precursor for preparing high-performance, structurally controllable iron-based sulfide materials.

[0009] In this invention, the role of thiourea is: (1) to act as a "slow-release" sulfur source under hydrothermal conditions, slowly releasing sulfur through hydrolysis. 2- or HS - The "slow release" characteristic of ions perfectly matches the requirement of "in-situ transformation" for MIL-101(Fe). It allows sulfide ions to react gradually and uniformly with the [Fe3O] cluster from the framework surface and pores of MIL-101(Fe), rather than destroying it instantly. This process is more like a "smooth power transfer", which allows the metal-organic framework to be orderly transformed into a sulfide framework, thereby maximizing the inheritance of the high porosity and regular morphology of the precursor. The unique reaction kinetics of thiourea is the key to achieving the structure-guided transformation of MIL-101(Fe). (2) The iron in MIL-101(Fe) is Fe(III), while the iron in the target products Fe7S8 and FeS2 is partly Fe(II), which means that a reduction process must accompany the sulfidation process. Thiourea and its decomposition products (such as cyanamide) have certain reducing properties. Thiourea provides both a sulfur source and acts as an in-situ reducing agent to reduce Fe(III) to Fe(II), avoiding the need for additional complex and potentially toxic reducing agents (such as N2H4 and NaBH4), simplifying the process and maintaining the purity of the system. (3) The core objective of this invention is to prepare Fe7S8 / FeS2 heterojunctions. The ratio and interfacial properties of the heterojunctions are crucial to their electronic structure and performance. This invention can precisely control the depth and extent of sulfidation / reduction by precisely controlling the hydrothermal temperature. The mild reactivity of thiourea provides a possible time and space window for precisely controlling the depth and extent of sulfidation / reduction. For example, in the early stages of the reaction, one sulfide (such as FeS2) may be generated first, and as the reaction proceeds and the reduction deepens, it may be partially converted into another (such as Fe7S8), thereby forming a tightly coupled heterojunction at the nanoscale. If a violently reacting sulfur source is used, this process will be completed instantaneously, leading to phase separation or the formation of a uniform single phase, making it impossible to achieve controllable heterostructure construction. (4) Thiourea hydrolysis produces NH3, which makes the reaction environment weakly alkaline, which helps to inhibit the excessive volatilization of H2S and can promote the formation of specific phases.

[0010] The hydrothermal synthesis process of this invention is a chemical / solution-driven process. Using MIL-101(Fe) as a precursor, the reaction is carried out in a hydrothermal reactor at a relatively low temperature. The metal clusters (ferrite clusters) of MIL-101(Fe) act as "anchor sites," reacting with a sulfur source to generate Fe7S8 and FeS2. Its organic framework serves as an in-situ template and carbon source during the reaction. The resulting sulfide nanoparticles grow along the original MOF framework, maximizing the inheritance and retention of the high porosity and regular morphology of the MIL-101 precursor. This allows the invention to "program" the pore structure of the final product by pre-designing the precursor structure.

[0011] This invention employs a hydrothermal synthesis method, where the sulfidation reaction can initiate simultaneously and uniformly from both the surface and interior of the MIL-101 framework in a solution environment. By precisely controlling the hydrothermal temperature, time, and sulfur source concentration, the degree of sulfidation can be controlled, thereby precisely regulating the ratio and distribution of the Fe7S8 and FeS2 phases and the formation of their interface (i.e., heterojunction) at the nanoscale, achieving the synergistic construction of heterojunctions and pores.

[0012] Specifically, In step (1), the mass ratio of MIL-101 (Fe):thiourea is (0.15-3):1. When the ratio is lower than 0.15:1, the amount of thiourea is excessive, making it easier to form the FeS2 phase, and unreacted S... 2- It may lead to an amorphous sulfide layer on the surface. When used as a lithium battery anode material, the initial capacity may be high, but due to the large volume effect of FeS2 during the conversion reaction, the cycle stability is poor. When the ratio is higher than 0.3:1, the iron source is excessive, which makes it easier to form the Fe7S8 phase, and there may even be precursor residues. When used as a lithium battery anode material, the capacity is low and the rate performance is poor.

[0013] In step (2), the solvent of the mixed solution is 70-80% of the volume of the reactor, and the reaction time is 24-26h.

[0014] In step (2), the material is washed three times alternately with deionized water and anhydrous ethanol; then vacuum dried at 60-80℃ for 8-12 hours. Alternating washing is used to achieve gradual replacement and more thorough cleaning. This invention first uses water to remove most of the high concentration of water-soluble inorganic salts, then uses ethanol to dissolve and remove organic impurities. If ethanol is used first, some organic impurities may precipitate or coat the particle surface, hindering subsequent cleaning of inorganic salts. Excessively high drying temperatures will accelerate the drying process, leading to material agglomeration, phase change, oxidation, and material damage. Considering all factors, this invention chooses vacuum drying at 60-80℃ for 8-12 hours.

[0015] In step (3), the mass ratio of FeS2 / Fe7S8-x to graphene oxide is (1-1.5):1. Graphene is used in this invention to increase the overall conductivity of the material, promote charge transfer kinetics, and its good mechanical properties allow it to act as a buffer, mitigating the volume changes of FeS2 / Fe7S8 during charge and discharge, and improving the cycle stability of the electrode. When the ratio is less than 1:1, the content of graphene oxide is too low, weakening the coating effect on FeS2 / Fe7S8; when the ratio is greater than 1.5:1, the content of graphene oxide is too high, leading to a decrease in the relative content of FeS2 / Fe7S8 and a reduction in material capacity.

[0016] Typically, the concentration of graphene oxide dispersion is 1-1.5 mg / mL, which avoids both excessively low concentrations resulting in a large graphene solution volume and excessively high concentrations leading to a long ultrasonic dispersion time. In this invention, the centrifugation speed is 8000 rpm, and the centrifugation time is 1-2 min.

[0017] A composite material of iron disulfide / iron octasulfide was obtained by the preparation method described above, which exhibits excellent electrochemical performance and can be applied to battery anode materials.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) Using MIL-101(Fe) as a precursor, its high iron content lays the material basis for subsequent conversion into sufficient and high-capacity iron-based sulfides; its structural stability enables MIL-101(Fe) to withstand the moderate temperature (usually 100-220℃) and solvent environment required for hydrothermal synthesis, ensuring that the subsequent sulfidation reaction can proceed in an orderly manner; its regular structure ensures the formation of a highly regular pore system.

[0019] (2) Thiourea provides both sulfur source and in-situ reducing agent, maximizing the inheritance of the high porosity and regular morphology of the precursor, avoiding the addition of complex and toxic reducing agents, simplifying the process and maintaining the purity of the system; the mild reactivity of thiourea provides a possible time and space window for precise control of the depth and degree of sulfidation / reduction.

[0020] (3) The low-temperature hydrothermal synthesis method is adopted. The reaction is carried out at a relatively low temperature, which has low energy consumption and a mild and controllable process. It inherits and retains the high porosity and regular morphology of the MIL-101 precursor to the maximum extent, solves the disadvantage of the difficulty in controlling the pore structure, and realizes the synergistic construction of heterojunction and pore.

[0021] (4) The biphase metal sulfide sample obtained in this invention is further ultrasonically composited with graphene oxide, which has a high specific surface area and good conductivity. The coating effect of graphene oxide further enhances the structural stability and improves the overall conductivity of the material. Attached Figure Description

[0022] Figure 1 Electron micrograph of FeS2 / Fe7S8-200; Figure 2 Electron micrograph of FeS2 / Fe7S8-220; Figure 3 Electron micrograph of FeS2 / Fe7S8-240; Figure 4 Electron micrograph of FeS2 / Fe7S8-220@GO; Figure 5 XRD patterns of FeS2 / Fe7S8-x (x=200, 220, 240) and FeS2 / Fe7S8-220@GO; Figure 6 Pore ​​size distribution diagrams for FeS2 / Fe7S8-x (x=200, 220, 240) and FeS2 / Fe7S8-220@GO; Figure 7 TGA / DTG curves for FeS2 / Fe7S8-x (x=200, 220, 240) and FeS2 / Fe7S8-220@GO; Figure 8 For FeS2 / Fe7S8-x (x=200, 220, 240) and FeS2 / Fe7S8-220@GO at 0.1 A g -1 Stability comparison under current density; Figure 9 Rate performance of FeS2 / Fe7S8-220@GO. Detailed Implementation

[0023] Example 1 (1) Dissolve 338 mg of MIL-101 (Fe) and 1700 mg of thiourea in 25 mL of deionized water respectively. After they are fully dissolved, mix them together and continue stirring for 10 minutes to obtain a mixture. (2) The mixed solution was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene, sealed and reacted at 220°C for 24 hours. After the reaction was completed, the mixture was centrifuged at 8000 rpm for 1 minute to obtain a black precipitate. The precipitate was washed three times with deionized water and anhydrous ethanol, and finally dried under vacuum at 60°C for 8 hours to obtain a biphase metal sulfide sample, labeled as FeS2 / Fe7S8-220, in which the proportion of heptasulfide was 58.9%.

[0024] Example 2 (1) Dissolve 338 mg of MIL-101 (Fe) and 1700 mg of thiourea in 25 mL of deionized water respectively. After they are fully dissolved, mix them together and continue stirring for 10 minutes to obtain a mixture. (2) The mixed solution was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene, sealed and reacted at 200 °C for 24 hours. After the reaction was completed, the mixture was centrifuged at 8000 rpm for 1 minute to obtain a black precipitate, which was washed three times with deionized water and anhydrous ethanol. Finally, it was vacuum dried at 60 °C for 8 hours to obtain a biphase metal sulfide sample, labeled as FeS2 / Fe7S8-200, in which the proportion of heptasulfide was 37.56%.

[0025] Example 3 (1) Dissolve 338 mg of MIL-101 (Fe) and 1700 mg of thiourea in 25 mL of deionized water respectively. After they are fully dissolved, mix them together and continue stirring for 10 minutes to obtain a mixture. (2) The mixed solution was transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene, sealed and reacted at 240 °C for 24 hours. After the reaction was completed, the mixture was centrifuged at 8000 rpm for 1 minute to obtain a black precipitate, which was washed three times with deionized water and anhydrous ethanol. Finally, it was vacuum dried at 60 °C for 8 hours to obtain a biphase metal sulfide sample, labeled as FeS2 / Fe7S8-240, in which the proportion of heptasulfide was 35.03%.

[0026] Example 4 (1) 50 mg of graphene oxide was ultrasonically dispersed in deionized water to obtain 1 mg / mL -1 Uniform graphene oxide dispersion; 50 mg of FeS2 / Fe7S8-220 prepared in Example 1 was ultrasonically dispersed in deionized water to obtain the sample dispersion; (2) The sample dispersion was added to the graphene oxide dispersion and ultrasonically stirred for 10 hours. After centrifugation at 8000 rpm for 2 minutes, the precipitate was freeze-dried for 20 hours to obtain the iron-based sulfide composite material, labeled as FeS2 / Fe7S8-220@GO, in which the proportion of heptasulfide was 59.58%.

[0027] Figure 1 Electron micrographs of FeS2 / Fe7S8-200 are shown, revealing a spherical morphology with rough particles on the surface. Figure 2 Electron micrographs of FeS2 / Fe7S8-220 are shown. As the temperature increases, FeS2 / Fe7S8-220 exhibits a more compact spherical structure with more rough wrinkles on the surface. Figure 3Electron micrographs of FeS2 / Fe7S8-240 are shown. Under higher temperature and pressure, the original octahedral structure of MIL-101 (Fe) collapses directly and is compressed into a sheet-like shape. Figure 4 Electron micrographs of FeS2 / Fe7S8-220@GO are shown. In addition to observing a spherical structure with rough wrinkles similar to FeS2 / Fe7S8-220, layered GO can also be clearly seen, indicating the successful preparation of FeS2 / Fe7S8-220@GO.

[0028] from Figure 5 It can be seen that the diffraction peaks in the XRD patterns of FeS2 / Fe7S8-x and FeS2 / Fe7S8-220@GO match the diffraction peaks of pyrite FeS2 (PDF#42-1340) and pyrrhotite Fe7S8 (PDF#29-0723), indicating the successful preparation of FeS2 / Fe7S8. No obvious identifiable GO diffraction peaks were observed in the FeS2 / Fe7S8-220@GO composite material, which may be due to its few-layered and highly dispersed GO nanosheets.

[0029] from Figure 6 It can be seen that all samples (FeS2 / Fe7S8-200, FeS2 / Fe7S8-220, FeS2 / Fe7S8-240, and FeS2 / Fe7S8-220@GO) exhibit a distribution peak at 4 nm, which is consistent with "structural inheritance." The observation of a distribution peak around 4 nm is strong evidence of the successful inheritance of the mesoporous structure of the precursor into the heptasulfide / ferric disulfide heterostructure. For FeS2 / Fe7S8-220@GO, the distribution peak at 4 nm is relatively sharp, indicating that the size of these mesopores is relatively uniform, which may be the result of ultrasonic dispersion. Distribution peaks also appeared in the 10-30 nm range, which is the result of graphene oxide composite.

[0030] from Figure 7The TGA and DTG results show that the oxidation of Fe7S8 and FeS2 is a relatively direct, single-step process, leading to a continuous decrease in their mass, as they are directly oxidized to Fe2O3 and SO2 (4Fe7S8 + 53O2 → 14Fe2O3 + 32SO2↑ (400~550℃), 4FeS2 + 11O2 → 2Fe2O3 + 8SO2↑ (550~600℃)). Calculations show that the proportions of Fe7S8 in FeS2 / Fe7S8-200, FeS2 / Fe7S8-220, and FeS2 / Fe7S8-240 are 37.56%, 58.9%, and 35.03%, respectively. Clearly, FeS2Fe7S8-220 has the highest Fe7S8 content, which is attributed to the competition between reaction kinetics and thermodynamics. Furthermore, the proportion of Fe7S8 in FeS2 / Fe7S8-200@GO is 59.58%, indicating that the structure of FeS2 / Fe7S8-200 is not damaged when it combines with GO.

[0031] The Fe 2p spectrum shows that the fitted peak is located at 707.7 eV (Fe 2p). 3 / 2 ) and 720.5 eV (Fe2p 1 / 2 ), attributed to Fe 2+ And a satellite peak at 714.0 eV. Located at 711.6 eV (Fe2p). 3 / 2 ) and 725.6 eV (Fe2p 1 / 2 The signal and a satellite peak at 733.5 eV indicate the presence of Fe. 3+ For S 2p, the four peaks are located at 161.6, 162.7, 164, and 167.8 eV, corresponding to S 2p. 3 / 2 S 2p 1 / 2 S 2- and SO x (Oxidation of metal sulfides in the air).

[0032] Example 5 Electrode and battery fabrication section The preparation process of the electrode sheet is as follows: The prepared samples (FeS2 / Fe7S8-200, FeS2 / Fe7S8-220, FeS2 / Fe7S8-240 and FeS2 / Fe7S8-220@GO), conductive carbon black (Super-P) and polyvinylidene fluoride (PVDF) are made into a slurry in a mass ratio of 7:2:1, coated on a pure copper foil current collector, and dried under vacuum at 50-70℃ for 24 hours to obtain the electrode sheet.

[0033] The half-cell preparation process is as follows: a circular electrode sheet with a diameter of 12 mm with holes punched in the prepared electrode sheet is used as the working electrode, the loading of electroactive material is about 1.8-2 mg·cm⁻², lithium metal foil is used as the counter electrode, 1.0 MLiPF6 ethylene carbonate / diethyl carbonate solution (volume ratio 1:1) is used as the electrolyte, and a polypropylene microporous membrane with a diameter of 16 mm is used as the separator. The half-cell is assembled into a CR2025 coin cell in an argon atmosphere glove box.

[0034] Figure 8 The results demonstrate the performance of FeS2 / Fe7S8-x (x=200, 220, 240) and FeS2 / Fe7S8-220@GO at 0.1 A g. -1 Cycling stability after 150 charge-discharge cycles at current density: The capacities of FeS2 / Fe7S8-x (x=200, 220, 240) and FeS2 / Fe7S8-220@GO after cycling were 556.2 mAh g⁻¹. -1 873.5 mAh g -1 423.1 mAh g -1 and 1380.7 mAh g -1 It can be seen that after 150 cycles, FeS2 / Fe7S8-220@GO has the highest discharge specific capacity. This is due to the more compact spherical structure of FeS2 / Fe7S8 obtained under optimal temperature control, with more rough wrinkles on the surface. Such a structure is more conducive to the structural stability of FeS2 / Fe7S8. In addition, the coating effect of graphene oxide further enhances the structural stability and improves the overall conductivity of the material.

[0035] Figure 9 The rate performance of FeS2 / Fe7S8-220@GO is demonstrated. It can be seen that FeS2 / Fe7S8-220@GO achieves good rate performance at current densities of 0.1, 0.2, 0.5, 1, 3, and 5 A g. -1 At that time, it exhibited high values ​​of 1223.2, 1015.2, 813.6, 709.2, 589.2 and 544.2 mAh g. -1 The reversible capacity indicates excellent rate performance. When the current density recovers to 0.1 A g... -1 At that time, the discharge specific capacity recovered to 1352.2 mAh g. -1 It exhibits excellent structural stability.

Claims

1. A method for preparing an iron-based sulfide composite material, characterized in that, MIL-101 (Fe) and thiourea were reacted under hydrothermal conditions and then reacted with graphene oxide to obtain an iron-based sulfide composite material.

2. The method for preparing an iron-based sulfide composite material according to claim 1, characterized in that, The specific steps are as follows: (1) Dissolve MIL-101 (Fe) and thiourea separately in deionized water. After they are fully dissolved, mix them together and continue stirring to obtain a mixed solution. (2) Transfer the mixed solution to a high-pressure reactor, seal it and react it at 200-240℃. After the reaction is completed, centrifuge, wash and dry the mixture to obtain a biphase metal sulfide sample. (3) Obtain a uniform graphene oxide dispersion by ultrasonically dispersing graphene oxide in deionized water; obtain a sample dispersion by ultrasonically dispersing a biphase metal sulfide sample in deionized water. (4) Mix the sample dispersion with the graphene oxide dispersion, stir ultrasonically, centrifuge and dry to obtain iron-based sulfide composite material.

3. The method for preparing an iron-based sulfide composite material according to claim 1, characterized in that, In step (1), the mass ratio of MIL-101 (Fe): thiourea is (0.15-0.3):

1.

4. The method for preparing an iron-based sulfide composite material according to claim 1, characterized in that, In step (2), the reaction time is 24-26 hours.

5. The method for preparing an iron-based sulfide composite material according to claim 1, characterized in that, In step (2), wash with deionized water and anhydrous ethanol alternately; vacuum dry at 60-80℃ for 8-12 hours.

6. The method for preparing an iron-based sulfide composite material according to claim 1, characterized in that, In step (3), the mass ratio of biphase metal sulfide sample to graphene oxide is (1-1.5):

1.

7. An iron-based sulfide composite material, characterized in that, It is obtained by the preparation method described in any one of claims 1-6.

8. The application of the iron-based sulfide composite material according to claim 7 in a battery, characterized in that, As a negative electrode material for batteries.

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