Preparation method and application of Fe2O3 / MOFs composite material

Abstract

The application discloses a preparation method and application of Fe2O3 / MOFs composite material, and the preparation method of the Fe2O3 / MOFs composite material is as follows: S1, uniformly mixing a trivalent iron source aqueous solution and a humic acid aqueous solution to obtain a mixed solution I, and performing hydrothermal reaction on the mixed solution I to obtain a precursor solution; S2, uniformly mixing the precursor solution and an organic ligand aqueous solution, wherein the organic ligand is a carboxylic acid or an imidazole multi-dentate small-molecule organic ligand, to obtain a mixed solution II, performing hydrothermal reaction on the mixed solution II, centrifuging, drying the obtained precipitate, and obtaining the Fe2O3 / MOFs composite material. The Fe2O3 / MOFs composite material is prepared based on a simple hydrothermal reaction, and when the Fe2O3 / MOFs composite material is used as an active material for preparing a LIBs negative electrode, the Fe2O3 / MOFs composite material exhibits high specific capacity, excellent cycle stability and rate performance and other advantages, and the long-term cycle stability and rate performance of pure Fe2O3 as an active material for the LIBs negative electrode are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery anode material technology, specifically relating to a method for preparing Fe2O3 / MOFs composite material and its application. Background Technology

[0002] Lithium-ion batteries (LIBs), as a rapidly developing and popular energy storage device in recent years, have advantages such as high energy density, good stability, and low self-discharge, and are considered to be able to effectively alleviate the current severe energy demand. Unfortunately, the graphite anode, currently the most widely used material in LIBs, has a relatively low theoretical specific capacity (372 mAh g⁻¹). -1 The poor rate performance of these materials is no longer sufficient to meet the demand for high-capacity, rapid energy storage. Therefore, it is imperative to develop and design alternative anode materials with higher capacity and superior rate performance.

[0003] Fe2O3, as one of the most representative transition metal oxides (TMOs), has a theoretically high specific capacity (1005 mAh g / g). -1 Fe2O3 anodes are considered a potential LIB anode material due to their numerous advantages, including low cost and environmental friendliness. However, the key issues hindering the practical application of Fe2O3 anodes are their poor cycling stability and severe volume expansion during cycling. Fortunately, as described in Electroanal. Chem. 2018, 817, 65-72 and Small 2022, 18, 2203918, designing composite materials with rich pore structures can effectively alleviate the volume expansion problem of Fe2O3 anodes. MOF materials, known for their high porosity, not only help overcome this defect, but their abundant active sites can also further enhance the lithium storage performance of composite electrodes.

[0004] In recent years, a large amount of research has focused on using MOF materials as precursors to prepare composite electrodes through hydrothermal / solvothermal reactions and subsequent pyrolysis treatment. This method can effectively improve the stability of TMOs-based electrodes (Fe2O3) and has been proven to be one of the important strategies for designing high-performance electrode materials. However, this performance improvement usually comes at the cost of sacrificing the MOF material. If the MOF material can be retained, the rich active sites and pore structure of MOFs can be fully utilized, and the advantages of each component in the composite material can be better leveraged.

[0005] Among various MOF materials, Fe-based MOFs have become one of the most popular electrode materials in the battery field in recent years due to their advantages such as low cost, low toxicity, simple preparation, and diverse structures. On the other hand, as summarized in the review article Coordin. Chem. Rev. 2020, 416, 213341, regulating the molecular structure of organic ligands is of great significance for improving the electrochemical performance of MOF-based electrodes. Summary of the Invention

[0006] Based on the above-mentioned prior art, the present invention provides a method for preparing Fe2O3 / MOFs composite materials and their applications. The present invention prepares Fe2O3 / MOFs composite materials based on a simple hydrothermal reaction. When used as an active material for preparing LIBs anodes, it exhibits advantages such as extremely high specific capacity, excellent cycle stability and rate performance, and significantly improves the poor long-term cycle stability and rate performance of pure Fe2O3 as an active material for LIBs anodes.

[0007] The technical solution adopted to achieve the above-mentioned objectives of this invention is as follows:

[0008] A method for preparing Fe2O3 / MOFs composite materials includes the following steps:

[0009] S1. Mix the ferric source aqueous solution and the humic acid aqueous solution evenly to obtain mixture I. Perform a hydrothermal reaction on mixture I to obtain the precursor solution.

[0010] S2. Mix the precursor solution and the aqueous solution of the organic ligand uniformly. The organic ligand is a carboxylic acid or imidazole-based multidentate small molecule organic ligand to obtain mixture II. Perform a hydrothermal reaction on mixture II. After the reaction is completed, centrifuge and dry the resulting precipitate to obtain the Fe2O3 / MOFs composite material.

[0011] Furthermore, the mass concentration of the trivalent iron source aqueous solution is 1-20%, and the mass concentration of the humic acid aqueous solution is 0.1-1%.

[0012] Furthermore, the ferric source is a water-soluble iron salt, and the ferric source is selected from at least one of ferric chloride, ferric nitrate, ferric sulfate, and ferric tribromide.

[0013] Furthermore, the molar ratio of the ferric source to the organic ligand is 1 to 4:1, and the mass ratio of the ferric source to humic acid is 1 to 10:1.

[0014] Furthermore, in steps S1 and S2, the hydrothermal reaction temperature is 150–190°C, and the hydrothermal reaction time is 8–24 h.

[0015] Furthermore, the organic ligand is selected from at least one of terephthalic acid, 2-aminoterephthalic acid, and 4,4'-biphenylacetic acid.

[0016] Furthermore, in step S2, when preparing the aqueous solution of the organic ligand, sodium hydroxide needs to be added to completely dissolve the organic ligand, and the mass concentration of the organic ligand in the aqueous solution is 0.3-0.7%, and the mass concentration of sodium hydroxide is 0.1-1%.

[0017] Application of Fe2O3 / MOFs composite material prepared by any of the above methods in lithium-ion batteries.

[0018] Furthermore, the Fe2O3 / MOFs composite material is used to prepare the negative electrode of a lithium-ion battery, and the specific preparation method is as follows:

[0019] Fe2O3 / MOFs composite material, conductive additive acetylene black, and binder polyvinylidene fluoride (PVDF) were added to the dispersion solvent N-methylpyrrolidone (NMP). The mass ratio of Fe2O3 / MOFs composite material, conductive additive acetylene black, and binder PVDF was 6:3:1 to 8:1:1, and the mass ratio of the above solids added to the dispersion solvent NMP was approximately 1:(6 to 10). The mixture was then magnetically stirred (stirring time not less than 12 hours) to ensure uniform dispersion, forming an electrode slurry. The electrode slurry was coated onto the surface of copper foil, dried, and finally stamped and cut to form a negative electrode sheet.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0021] 1. This invention is based on a simple hydrothermal reaction and prepares Fe2O3 / MOFs composite materials through a co-precipitation method. Furthermore, by controlling the organic ligands of MOFs materials, a variety of Fe2O3 / MOF composite materials have been developed, thereby obtaining high-performance LIBs anode materials. This has significant practical implications and is expected to become a highly promising strategy for preparing high-performance LIBs electrodes.

[0022] 2. This invention can obtain a composite electrode material that is loaded with Fe2O3 and retains the MOF structure without any subsequent high-temperature heat treatment, and it is compatible with a variety of organic ligands, thus having extremely high versatility.

[0023] 3. This invention uses humic acid, a biomass material, as a conductive carbon additive in composite materials, which has significant cost advantages and makes the prepared electrode material more environmentally friendly.

[0024] 4. Compared with the original Fe2O3 electrode, the electrode prepared by the Fe2O3 / MOFs composite material of the present invention has advantages such as high specific capacity, excellent cycle stability and rate performance.

[0025] 5. The process of this invention is simple, the synthesis conditions are mild, the cost is low, and the reproducibility is high, making it suitable for large-scale industrial production. Attached Figure Description

[0026] Figure 1 The image shows a SEM image of the Fe2O3 / MOFs composite material prepared in Example 1.

[0027] Figure 2The N2 adsorption / desorption isotherm is shown for the Fe2O3 / MOFs composite material prepared in Example 1.

[0028] Figure 3 The image shows the pore size distribution of the Fe2O3 / MOFs composite material prepared in Example 1.

[0029] Figure 4 The image shows the cyclic voltammetry curves of the Fe2O3 / MOFs composite material prepared in Example 1.

[0030] Figure 5 The Fe2O3 / MOFs composite material prepared in Example 1 was used in 0.1A g... -1 The constant current charge and discharge curves are shown below.

[0031] Figure 6 The images show the XRD patterns of the Fe2O3 / MOFs composite materials prepared in Examples 1-3 and Comparative Examples 1-3.

[0032] Figure 7 The graph shows a comparison of the rate performance of the Fe2O3 / MOFs composite material prepared in Example 1 and the pure Fe2O3 in Comparative Example 1.

[0033] Figure 8 The Fe2O3 / MOFs composite materials prepared in Examples 1-3 and Comparative Examples 1-3, as well as the pure Fe2O3 in Comparative Example 4, were prepared at 0.1 A g. -1 The following is a comparison chart of the cycle performance. Detailed Implementation

[0034] The present invention will now be described in detail with reference to specific embodiments.

[0035] Example 1

[0036] 1. Dissolve 300 mg FeCl3 in 10 ml of deionized water to obtain an aqueous solution of FeCl3.

[0037] 2. Dissolve 110 mg of humic acid in 20 ml of deionized water to obtain an aqueous solution of humic acid.

[0038] 3. Mix FeCl3 aqueous solution and humic acid aqueous solution, stir magnetically for 10 min, and then sonicate for 40 min to obtain mixture I. Transfer mixture I to a high-pressure reactor made of polytetrafluoroethylene and hydrothermally react at 190℃ for 12 h. After the reaction is completed, cool to room temperature and sonicate the cooled mixture for 20 min to obtain the precursor solution.

[0039] 4. Add 120 mg of 2-aminoterephthalic acid (ATA) to 30 ml of deionized water, and add about 40 mg of NaOH while stirring to completely dissolve it, so as to obtain an aqueous solution of 2-aminoterephthalic acid.

[0040] 5. Add the aqueous solution of 2-aminoterephthalic acid to the precursor solution and stir magnetically for 10 min to obtain mixture II. Transfer mixture II to a high-pressure reactor made of polytetrafluoroethylene and hydrothermally react at 190℃ for 12 h. After the reaction is complete, cool to room temperature and transfer the cooled mixture to a centrifuge tube. Centrifuge at 6000 r / min for 5 min, remove the supernatant, add deionized water, shake the centrifuge tube vigorously, and centrifuge again. Repeat this operation 3-4 times. Discard the supernatant and transfer the obtained precipitate to a freeze dryer. Vacuum dry at -50℃ and 1 Pa for one day to obtain the Fe2O3 / MOFs composite material.

[0041] The Fe2O3 / MOFs composite material prepared in Example 1 was scanned using a scanning electron microscope, and the resulting SEM images are shown below. Figure 1 As shown, from Figure 1 It can be seen that the prepared Fe2O3 / MOFs composite electrode material exhibits a unique cauliflower-like structure, and abundant pore structures can be observed on the material surface. This porous structure can effectively alleviate the volume expansion of Fe2O3 during the charging and discharging process.

[0042] The Fe2O3 / MOFs composite material prepared in Example 1 was subjected to N2 adsorption-desorption experiments. The resulting N2 adsorption / desorption isotherms are shown below. Figure 2 As shown, the obtained aperture distribution diagram is as follows: Figure 3 As shown. From Figure 2 It can be seen that the prepared Fe2O3 / MOFs composite material exhibits a type IV isotherm and a hysteresis loop in the range of P / P0≈0.75-0.95, indicating that the composite material contains a large number of mesopores. Figure 3 The pore size distribution diagram further confirms this conclusion. Calculations based on the BET model and BJH method show that the specific surface area of ​​the prepared Fe₂O₃ / MOFs composite material is 99.4 m². 2 g -1 The average pore size is 27.0 nm.

[0043] The Fe2O3 / MOFs composite material prepared in Example 1 was subjected to cyclic voltammetry testing at a scan rate of 0.1 mV / s. -1 The voltage range was 0–3V, and the test temperature was 30℃. The resulting cyclic voltammetry curve is shown below. Figure 4 As shown, Figure 4The significant difference in curves between the first and subsequent scan cycles stems from the formation of the SEI film, the decomposition of the electrolyte, and the occurrence of irreversible reactions. The curves showed no significant distortion in subsequent cycles, indicating that the prepared Fe2O3 / MOFs composite material possesses excellent reversibility and stability.

[0044] The Fe2O3 / MOFs composite material prepared in Example 1 was assembled into a coin cell, and the result was obtained at a current density of 0.1 Ag. -1 A constant current charge-discharge test was performed, and the resulting constant current charge-discharge curves are shown below. Figure 5 As shown, the high discharge specific capacity in the first cycle originates from the formation of the SEI film and irreversible side reactions, which is very consistent with the results of the cyclic voltammetry curves. The prepared Fe2O3 / MOFs composite material gradually increases in specific capacity within 10-30 cycles and remains stable within 40-50 cycles.

[0045] Comparative Example 1

[0046] 1. Dissolve 300 mg FeCl3 in 10 ml of deionized water to obtain an aqueous solution of FeCl3.

[0047] 2. Add 120 mg of 2-aminoterephthalic acid (ATA) to 30 ml of deionized water, and add about 40 mg of NaOH while stirring to completely dissolve it, so as to obtain an aqueous solution of 2-aminoterephthalic acid.

[0048] 3. Mix FeCl3 aqueous solution and 2-aminoterephthalic acid aqueous solution, stir magnetically for 10 min, then transfer the mixture to a high-pressure reactor made of polytetrafluoroethylene, and hydrothermally react at 190℃ for 12 h. After the reaction is complete, cool to room temperature, transfer the cooled mixture to a centrifuge tube, centrifuge at 6000 r / min for 5 min, remove the supernatant, replenish with deionized water, shake the centrifuge tube vigorously and centrifuge again, repeat this operation 3-4 times, discard the supernatant, transfer the obtained precipitate to a freeze dryer, and vacuum dry at -50℃ and 1 Pa for one day to obtain Fe2O3 / MOFs composite material without HA composite.

[0049] Example 2

[0050] 1. Dissolve 300 mg FeCl3 in 10 ml of deionized water to obtain an aqueous solution of FeCl3.

[0051] 2. Dissolve 110 mg of humic acid in 20 ml of deionized water to obtain an aqueous solution of humic acid.

[0052] 3. Mix FeCl3 aqueous solution and humic acid aqueous solution, stir magnetically for 10 min, and then sonicate for 40 min to obtain mixture I. Transfer mixture I to a high-pressure reactor made of polytetrafluoroethylene and hydrothermally react at 190℃ for 12 h. After the reaction is completed, cool to room temperature and sonicate the cooled mixture for 20 min to obtain the precursor solution.

[0053] 4. Add 110 mg of terephthalic acid (PTA) to 30 ml of deionized water, and add about 40 mg of NaOH while stirring until it is completely dissolved to obtain an aqueous solution of terephthalic acid.

[0054] 5. Add the aqueous solution of terephthalic acid to the precursor solution and stir magnetically for 10 min to obtain mixture II. Transfer mixture II to a high-pressure reactor made of polytetrafluoroethylene and hydrothermally react at 190℃ for 12 h. After the reaction is complete, cool to room temperature and transfer the cooled mixture to a centrifuge tube. Centrifuge at 6000 r / min for 5 min, remove the supernatant, add deionized water, shake the centrifuge tube vigorously, and centrifuge again. Repeat this operation 3-4 times. Discard the supernatant and transfer the obtained precipitate to a freeze dryer. Vacuum dry at -50℃ and 1 Pa for one day to obtain the Fe2O3 / MOFs composite material.

[0055] Comparative Example 2

[0056] 1. Dissolve 300 mg FeCl3 in 10 ml of deionized water to obtain an aqueous solution of FeCl3.

[0057] 2. Add 110 mg of terephthalic acid (PTA) to 30 ml of deionized water, and add about 40 mg of NaOH while stirring until it is completely dissolved to obtain an aqueous solution of terephthalic acid.

[0058] 3. Mix FeCl3 aqueous solution and terephthalic acid aqueous solution, stir magnetically for 10 min, then transfer the mixture to a high-pressure reactor made of polytetrafluoroethylene, and hydrothermally react at 190℃ for 12 h. After the reaction is complete, cool to room temperature, transfer the cooled mixture to a centrifuge tube, centrifuge at 6000 r / min for 5 min, remove the supernatant, replenish with deionized water, shake the centrifuge tube vigorously and centrifuge again, repeat this operation 3-4 times, discard the supernatant, transfer the obtained precipitate to a freeze dryer, and vacuum dry at -50℃ and 1 Pa for one day to obtain Fe2O3 / MOFs composite material without HA composite.

[0059] Example 3

[0060] 1. Dissolve 300 mg FeCl3 in 10 ml of deionized water to obtain an aqueous solution of FeCl3.

[0061] 2. Dissolve 110 mg of humic acid in 20 ml of deionized water to obtain an aqueous solution of humic acid.

[0062] 3. Mix FeCl3 aqueous solution and humic acid aqueous solution, stir magnetically for 10 min, and then sonicate for 40 min to obtain mixture I. Transfer mixture I to a high-pressure reactor made of polytetrafluoroethylene and hydrothermally react at 190℃ for 12 h. After the reaction is completed, cool to room temperature and sonicate the cooled mixture for 20 min to obtain the precursor solution.

[0063] 4. Add 160 mg of 4,4'-biphenyldicarboxylic acid (BPDC) to 30 ml of deionized water, and add about 40 mg of NaOH while stirring to completely dissolve it, so as to obtain an aqueous solution of 4,4'-biphenyldicarboxylic acid.

[0064] 5. Add the aqueous solution of 4,4'-biphenyl dicarboxylic acid to the precursor solution and stir magnetically for 10 min to obtain mixture II. Transfer mixture II to a high-pressure reactor made of polytetrafluoroethylene and hydrothermally react at 190℃ for 12 h. After the reaction is complete, cool to room temperature and transfer the cooled mixture to a centrifuge tube. Centrifuge at 6000 r / min for 5 min, remove the supernatant, add deionized water, shake the centrifuge tube vigorously, and centrifuge again. Repeat this operation 3-4 times. Discard the supernatant and transfer the obtained precipitate to a freeze dryer. Vacuum dry at -50℃ and 1 Pa for one day to obtain the Fe2O3 / MOFs composite material.

[0065] Comparative Example 3

[0066] 1. Dissolve 300 mg FeCl3 in 10 ml of deionized water to obtain an aqueous solution of FeCl3.

[0067] 2. Add 160 mg of 4,4'-biphenyldicarboxylic acid (BPDC) to 30 ml of deionized water, and add about 40 mg of NaOH while stirring to completely dissolve it, so as to obtain an aqueous solution of 4,4'-biphenyldicarboxylic acid.

[0068] 3. Mix FeCl3 aqueous solution and 4,4'-biphenyl dicarboxylic acid aqueous solution, stir magnetically for 10 min, then transfer the mixture to a high-pressure reactor made of polytetrafluoroethylene, and hydrothermally react at 190℃ for 12 h. After the reaction is complete, cool to room temperature, transfer the cooled mixture to a centrifuge tube, centrifuge at 6000 r / min for 5 min, remove the supernatant, replenish with deionized water, shake the centrifuge tube vigorously and centrifuge again, repeat this operation 3-4 times, discard the supernatant, transfer the obtained precipitate to a freeze dryer, and vacuum dry at -50℃ and 1 Pa for one day to obtain Fe2O3 / MOFs composite material without HA composite.

[0069] The Fe2O3 / MOFs composite materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to X-ray diffraction (XRD) analysis, and the obtained XRD patterns are shown below. Figure 6 As shown, by Figure 6 It can be seen that the characteristic diffraction peak of γ-Fe2O3 (JCPDS card No. 33-664) can be clearly observed in the Fe2O3 / MOFs composite materials prepared in Examples 1-3 and Comparative Examples 1-3, thus confirming the presence of Fe2O3 in the Fe2O3 / MOFs composite materials prepared in Examples 1-3 and Comparative Examples 1-3.

[0070] Comparative Example 4

[0071] Pure Fe2O3 was directly used as the active material for preparing the negative electrode of lithium batteries.

[0072] The specific capacitance of the Fe2O3 / MOFs composite material and pure Fe2O3 prepared in Example 1 was tested at different current densities, with a voltage range of 0–3V and a test temperature of 30℃. The resulting rate performance graph is shown in Figure 1. Figure 7 As shown, by Figure 7 As can be seen, compared with pure Fe2O3 in Comparative Example 4, the prepared Fe2O3 / MOFs composite electrode material exhibits good stability at various current densities, demonstrating excellent rate performance and reversibility. This indicates that the method for preparing Fe2O3 / MOFs composite materials in this invention effectively improves the poor cycle stability and rate performance of pure Fe2O3, while providing considerable specific capacity, and shows promise as a potential alternative to LIBs anodes.

[0073] The Fe2O3 / MOFs composite materials prepared in Examples 1-3 and Comparative Examples 1-3, and the pure Fe2O3 in Comparative Example 4 were subjected to cyclic stability tests (100 cycles, 0.1A g). -1 Under the condition that the voltage range is 0–3V, the obtained cycle stability performance is as follows: Figure 8 As shown, by Figure 8As can be seen, the Fe2O3 / MOFs composite material prepared in Example 1 exhibits the highest capacity and best stability, with a specific capacity as high as 1396 mAh g after 100 cycles. -1 The Fe2O3 / MOFs composite material prepared in Comparative Example 1 maintained a specific capacity of 535 mAh g after 100 cycles. -1 Although the pure Fe₂O₃ in Comparative Example 4 exhibited a high specific capacity during the initial cycling process, it rapidly decreased during subsequent cycles, showing the lowest specific capacity (433 mAh g⁻¹) after 100 cycles. -1 ).

[0074] according to Figure 8 The comparison shows that the Fe2O3 / MOFs composite material prepared in Example 2 maintained a specific capacity of 830 mAh g after 100 cycles. -1 The Fe2O3 / MOFs composite material prepared in Comparative Example 2 maintained a specific capacity of 703 mAh g after 100 cycles. -1 .

[0075] according to Figure 8 The comparison shows that the Fe2O3 / MOFs composite material prepared in Example 3 maintained a specific capacity of 767 mAh g after 100 cycles. -1 The Fe2O3 / MOFs composite material prepared in Comparative Example 3 maintained a specific capacity of 479 mAh g⁻¹ after 100 cycles. -1 .

[0076] In the aforementioned cyclic voltammetry and constant current charge-discharge tests, Fe2O3 / MOFs composite materials and pure Fe2O3 were used as the active material to prepare the working electrode. These were then assembled into CR2032 coin cells in an argon glove box. The coin cells were tested on an electrochemical workstation and a Xinwei battery testing system. In the coin cells: the electrolyte was a 1M LiPF6 in EC+DEC (1:1, vol%) commercial electrolyte; the counter electrode was a 1mm thick lithium metal sheet; and the separator was a Celgard 2325 separator.

Claims

1. A method for preparing a Fe2O3 / MOFs composite material for use as a negative electrode active material in lithium-ion batteries, characterized in that... Includes the following steps: S1. Mix the ferric source aqueous solution and the humic acid aqueous solution evenly to obtain mixture I. Perform a hydrothermal reaction on mixture I at a temperature of 150~190℃ for 8~24 h to obtain a precursor solution. The trivalent iron source is a water-soluble iron salt; S2. Mix the precursor solution with the aqueous solution of 2-aminoterephthalic acid to obtain mixture II. Perform a hydrothermal reaction on mixture II at a temperature of 150~190℃ for 8~24 h. After the reaction is complete, centrifuge and dry the resulting precipitate to obtain cauliflower-shaped Fe2O3 / MOFs composite material.

2. The method for preparing the Fe2O3 / MOFs composite material according to claim 1, characterized in that: The mass concentration of the trivalent iron source aqueous solution is 1~20%, and the mass concentration of the humic acid aqueous solution is 0.1~1%.

3. The method for preparing the Fe2O3 / MOFs composite material according to claim 1, characterized in that: The trivalent iron source is selected from at least one of ferric chloride, ferric nitrate, ferric sulfate, and ferric tribromide.

4. The method for preparing the Fe2O3 / MOFs composite material according to claim 1, characterized in that: The molar ratio of the ferric source to the organic ligand is 1~4:1, and the mass ratio of the ferric source to humic acid is 1~10:

1.

5. The method for preparing the Fe2O3 / MOFs composite material according to claim 1, characterized in that: In step S2, when preparing the aqueous solution of the organic ligand, sodium hydroxide needs to be added to completely dissolve the organic ligand. The mass concentration of the organic ligand in the aqueous solution is 0.3~0.7%, and the mass concentration of sodium hydroxide is 0.1~1%.

6. The application of an Fe2O3 / MOFs composite material prepared by any one of claims 1-5 in a lithium-ion battery, wherein the Fe2O3 / MOFs composite material is used as an active material for preparing a negative electrode of a lithium-ion battery.

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