Carbon cloth supported iron oxide material, preparation method and application thereof

Abstract

The application discloses a preparation method of carbon cloth loaded iron oxide material, and the method comprises the following steps: soaking the carbon cloth in a nitric acid solution, cleaning and drying the carbon cloth after taking out, and obtaining pretreated carbon cloth; adding iron chloride hexahydrate and sodium acetate into ethylene glycol, stirring and dissolving to obtain a mixed solution, transferring the mixed solution into a stainless steel autoclave with a polytetrafluoroethylene lining, putting the pretreated carbon cloth into the autoclave and sealing, carrying out hydrothermal reaction at 170-190 DEG C, taking out and cleaning after the reaction is completed, obtaining a precursor, soaking the precursor in a mixed solution of 2-methyl imidazole and cobalt nitrate, cleaning and vacuum drying after taking out, and finally calcining under the protection of argon, thereby obtaining the carbon cloth loaded iron oxide material. Compared with the prior art, the carbon cloth loaded iron oxide material has excellent conductivity, electrochemical performance and mechanical stability, is particularly suitable for being used as a negative electrode of a lithium ion battery, and a lithium battery assembled by using the material shows good cycle stability and rate performance, and has a good application prospect in lithium ion energy storage devices.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a carbon cloth-supported iron oxide material, its preparation method, and its application. Background Technology

[0002] In recent years, with the growing acceptance of high-quality energy development and environmentally friendly strategies in the new era, lithium-ion battery technology has been widely applied in human production and daily life, such as in new energy electric vehicles and wearable electronic devices. However, with technological advancements, the demand for high-capacity, safe, and reliable batteries is increasing. Currently, graphite is the commonly used negative electrode material for lithium-ion batteries, but its theoretical capacity is relatively low and cannot meet the ever-growing demand for high capacity. Therefore, finding new materials with high capacity, stability, and safety has become a research hotspot.

[0003] Currently, research on lithium-ion battery anode materials mainly focuses on the following categories: carbon materials, transition metal oxides, and Mxene. Among them, iron oxide has attracted widespread attention due to its high theoretical capacity, low cost, and environmental friendliness. However, single iron oxide materials suffer from poor conductivity, large volume expansion, and are prone to breakage during charge and discharge, leading to unstable cycle performance. Therefore, improving the conductivity and cycle stability of iron oxide materials is a key technical problem that urgently needs to be solved. The mainstream approaches to solving this problem fall into two categories: one is to prepare iron oxide particles into various nanostructures, such as nanowires and nanorods, to improve material stability and reduce stress during volume changes. However, electrode fabrication using this method requires the addition of a binder, resulting in low conductivity; the other approach is to combine iron oxide with carbon materials. Carbon materials have excellent conductivity, which can improve the conductivity of the composite material while providing a self-supporting structure, avoiding the need for a binder. However, this method does not achieve ideal results in improving material stability. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing carbon cloth-supported iron oxide materials. The prepared carbon cloth-supported iron oxide materials have excellent electrical conductivity, electrochemical performance and mechanical stability.

[0005] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a carbon cloth-supported iron oxide material includes the following steps:

[0007] S1. Soak the carbon cloth in nitric acid solution, take it out, wash it and vacuum dry it to obtain the pretreated carbon cloth;

[0008] S2. Add ferric chloride hexahydrate and sodium acetate to ethylene glycol, stir and dissolve to obtain a mixed solution. Transfer the mixed solution to a stainless steel autoclave lined with polytetrafluoroethylene, put in the pretreated carbon cloth and seal it. Perform hydrothermal reaction at 170-190℃ for 10-16 hours. After the reaction is completed, take it out, wash it and obtain the precursor.

[0009] S3. The precursor is immersed in a mixed solution of 2-methylimidazole and cobalt nitrate. After the immersion is completed, it is removed, cleaned, vacuum dried, and finally calcined at 400-600℃ under argon protection to obtain carbon cloth-supported iron oxide material.

[0010] Furthermore, in step S1, the volume concentration of the nitric acid solution is 60%-70%.

[0011] Furthermore, in step S1, the cleaning process involves first ultrasonically cleaning with acetone for 90 minutes, and then rinsing thoroughly with deionized water.

[0012] Furthermore, in step S1, the temperature of the vacuum drying is 80°C.

[0013] Furthermore, in step S2, the molar ratio of ferric chloride hexahydrate to sodium acetate is 1:(2-2.5).

[0014] Furthermore, in step S2, the hydrothermal reaction temperature is 180℃ and the time is 12 hours. Under these conditions, the iron(III) oxide on the carbon fiber surface is uniformly distributed without obvious agglomeration.

[0015] Furthermore, in step S3, the soaking temperature is 80-90℃ and the soaking time is 10-15h.

[0016] Furthermore, in step S3, the concentration of 2-methylimidazole in the mixed solution of 2-methylimidazole and cobalt nitrate is 4-6 mol / L, and the concentration of cobalt nitrate is 1-2 mol / L.

[0017] Furthermore, in step S3, the heating rate is 5℃ / min, the calcination temperature is 500℃, and the calcination time is 2h. Under these conditions, Co-MOFs exhibit strong stability and a uniformly distributed porous structure.

[0018] The carbon cloth-supported iron oxide material was prepared using the above method.

[0019] Application of carbon cloth-supported iron oxide material prepared by the above method in the preparation of lithium-ion battery anodes.

[0020] The principle of this invention: This invention loads particulate iron oxide active material onto carbon cloth, greatly improving the conductivity of the iron oxide anode material. Simultaneously, it avoids the significant limitations imposed by uneven dispersion of active materials during electrode coating and the use of inactive components such as binders and conductive agents (conductive carbon black), forming a self-supporting structure. To further enhance the stability of the iron oxide composite material, a metal-organic framework (MOF) is grown on the surface of the carbon cloth@Fe3O4 composite material. MOFs are formed by strong chemical bonds between metal cations and organic ligands, possessing high specific surface area and unique stability. The pores of the MOF material can fill the electrolyte, enhancing lithium-ion diffusion and reducing battery impedance, exhibiting excellent performance in Li+ storage. Combining iron oxide material with a metal-organic framework on a carbon cloth substrate to form a unique three-dimensional structure is an effective strategy for improving the electrochemical performance of lithium-ion batteries (LIBs).

[0021] The beneficial effects of this invention are:

[0022] (1) This invention discloses a method for preparing carbon cloth-supported iron oxide material. The prepared carbon cloth-supported iron oxide material is a three-dimensional structure of carbon cloth@Fe3O4@Co-MOFs. In the carbon cloth-supported iron oxide material, the mass percentage content of carbon cloth and cobalt metal-organic framework is 89-90%, the mass percentage content of iron oxide is 10-11%, and the iron oxide particles are uniformly covered on the carbon fiber rods of carbon cloth. Both the cobalt metal-organic framework and the carbon fiber rods are micron-sized. The pore size of the cobalt metal-organic framework is about 20 nm, and the diameter of the carbon fiber rods is 10-12 μm.

[0023] (2) This invention achieves a synergistic effect by uniformly growing and covering iron oxide nanoparticles on carbon fiber rods, and then encapsulating them with porous Co-MOFs on the surface of the nanoparticles. This process retains the excellent conductivity of carbon fibers and the stability of Co-MOFs, thereby improving the electrochemical performance and mechanical stability of the iron oxide composite material. The three-dimensional structure of the composite material consists of three layers: a carbon fiber substrate and a porous upper layer. These layers work together to encapsulate the active nanoparticles, allowing the composite material to adapt to volume changes during charging and discharging, thus increasing its mechanical properties. Simultaneously, the porous outer layer effectively reduces the diffusion distance of lithium ions, increasing the contact area between the electrode and the electrolyte.

[0024] (3) The carbon cloth loaded iron oxide material of the present invention is used as a self-supporting flexible electrode for lithium ions. The battery assembled with carbon cloth@Fe3O4@Co-MOFs three-dimensional material as negative electrode and lithium sheet as positive electrode exhibits good cycle stability and rate performance, and has great application prospects in the preparation of lithium ion energy storage devices. Attached Figure Description

[0025] Figure 1 Scanning electron microscope image and elemental analysis diagram of the carbon cloth-supported iron oxide material prepared in Example 1;

[0026] Figure 2 The image shows the XRD pattern of the carbon cloth-supported iron oxide material prepared in Example 1.

[0027] Figure 3 The image shows the Bet test results of the carbon cloth-supported iron oxide material prepared in Example 1.

[0028] Figure 4 The image shows the Raman spectrum of the carbon cloth-supported iron oxide material prepared in Example 1.

[0029] Figure 5 The X-ray photoelectron spectroscopy spectrum of the carbon cloth-supported iron oxide material prepared in Example 1 is shown below.

[0030] Figure 6 The electrochemical impedance spectroscopy of the carbon cloth-supported iron oxide material prepared in Example 1;

[0031] Figure 7 The results show the cycle performance of a lithium-ion battery assembled using the carbon cloth-supported iron oxide material prepared in Example 1 as the negative electrode at a current of 1 A / g.

[0032] Figure 8 The results show the cycle performance of a lithium-ion battery assembled using the carbon cloth-supported iron oxide material prepared in Example 1 as the negative electrode at currents of 6 A / g and 10 A / g.

[0033] Figure 9 The graph shows the rate performance of a lithium-ion battery assembled using the carbon cloth-supported iron oxide material prepared in Example 1 as the negative electrode at different current densities. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] A method for preparing a carbon cloth-supported iron oxide material includes the following steps:

[0037] S1. Immerse a 3cm×3cm carbon cloth in a 65% nitric acid solution, remove it and ultrasonically clean it with acetone for 90 minutes, then clean it with deionized water, and vacuum dry it at 80℃ to obtain the pretreated carbon cloth.

[0038] S2. Add 20 mmol of ferric chloride hexahydrate and 44 mmol of sodium acetate to 60 mL of ethylene glycol. After stirring and dissolving, a mixed solution is obtained. The mixed solution is transferred to a stainless steel autoclave lined with polytetrafluoroethylene. The pretreated carbon cloth is placed in the autoclave and sealed. The autoclave is hydrothermally reacted at 180 °C for 12 h. After the reaction is completed, the autoclave is removed and washed three times with deionized water to obtain the precursor (carbon cloth@Fe3O4 precursor).

[0039] S3. The precursor was immersed in 80 mL of a mixed solution of 2-methylimidazole and cobalt nitrate (2-methylimidazole concentration was 4 mol / L, and cobalt nitrate concentration was 1.25 mol / L), kept at 85 °C for 12 h, removed and washed with deionized water, then dried under vacuum at 60 °C, and finally calcined at 500 °C for 2 h under argon protection at a rate of 5 °C / min to obtain carbon cloth supported iron oxide material, namely carbon cloth@Fe3O4@Co-MOFs composite material.

[0040] Figure 1 The images show scanning electron microscope (SEM) images and elemental analysis diagrams of the carbon cloth-supported iron oxide material prepared in Example 1. Figure 1 (a) is a scanning electron microscope image of carbon cloth-supported iron oxide material. Figure 1 (b) is an HR-TEM image of carbon cloth-supported iron oxide material. Figure 1 (c)- Figure 1 (f) is the elemental mapping diagram of the carbon cloth-supported iron oxide material. Figure 1 (a) It can be seen that iron oxide nanoparticles are uniformly coated on the carbon fiber rods of the carbon cloth in a particulate form, and the cobalt metal-organic framework is wrapped around the active particles in a porous, spiky manner. Both the cobalt metal-organic framework and the carbon fiber rods are micrometer-sized. Figure 1 (b) It can be seen that the porous Co-MOFs are uniformly distributed on the carbon fibers, with iron oxide particles encapsulated within them, providing not only a good conductive network but also facilitating electron transport within the electrode material. Figure 1 (c)- Figure 1 (f) shows that the elemental mapping image displays Fe (green), O (blue), C (red), and Co (purple) elements, and proves that Fe, O, C, and Co elements exist in the material and are uniformly distributed.

[0041] Figure 2The XRD pattern of the carbon cloth-supported iron oxide material prepared in Example 1 shows that, compared with carbon cloth, the carbon cloth@Fe3O4 precursor exhibits obvious diffraction peaks at 30.1°, 35.5°, and 43.1°, confirming that iron oxide (Fe3O4) was successfully hydrothermally grown on the surface of the carbon cloth fibers after step S2. In the XRD spectrum of the carbon cloth@Fe3O4@Co-MOFs composite material prepared in Example 1, the XRD peaks of iron oxide are covered by the peaks of Co-MOFs, indicating that Co-MOFs grow on the surface of the carbon cloth@Fe3O4 precursor and encapsulate the iron oxide nanoparticles, which can improve the stability of the material.

[0042] Figure 3 The image shows the Bet test results for the carbon cloth-supported iron oxide material prepared in Example 1. It can be seen that the surface area of ​​the carbon cloth-supported iron oxide material is 42 cm². 2 g -1 The average pore size distribution is concentrated around 20 nm.

[0043] Figure 4 The image shows the Raman spectrum of the carbon cloth-supported iron oxide material prepared in Example 1, at 1341 cm⁻¹. -1 The D band peak and the G band peak at 1577 cm⁻¹ confirm the formation of the graphite carbon layer, with IG / ID = 1.17.

[0044] Figure 5 The X-ray photoelectron spectroscopy spectrum of the carbon cloth-supported iron oxide material prepared in Example 1 is shown below. Figure 5 A is the full spectrum. Figure 5 B is the Co 2p diagram. Figure 5 C is the C1s plot. Figure 5 D is the O1s plot. Figure 5 E represents the Fe 2p diagram. Figure 5 F is the N1s spectrum, which indicates that the carbon cloth-supported iron oxide material is composed of elements such as Co, Fe, N, O, and C. Figure 5 Spectrum A indicates Co 2+ The existence of these materials fully demonstrates that Co-MOFs were synthesized on carbon cloth@Fe3O4Co-MOFs. Furthermore... Figure 5 D and Figure 5 E proved the successful synthesis of iron(III) oxide, combined with Figure 2 The results of the heated XRD pattern further confirmed the successful preparation of carbon cloth-supported iron oxide material (carbon cloth@Fe3O4@Co-MOFs).

[0045] Figure 6The image shows the electrochemical impedance spectroscopy (EIS) of the carbon cloth-supported iron oxide material prepared in Example 1. The semicircles in the figure reflect the resistance of the SEI layer and the charge transfer resistance between the electrode surface and the electrolyte. It can be seen that the semicircle diameter of the carbon cloth@Fe3O4@Co-MOFs composite material prepared in Example 1 is smaller than that of carbon cloth@Fe3O4 and Fe3O4, indicating lower charge transfer resistance and lower electronic properties. This demonstrates that the three-dimensional structure can improve the conductivity of the material.

[0046] The carbon cloth-supported iron oxide material prepared in Example 1 was used to prepare the negative electrode of a lithium-ion battery, and then assembled into a lithium-ion battery. The performance of the lithium-ion battery was then tested. The specific method is as follows:

[0047] 1) Lithium battery assembly: Electrochemical tests were conducted using CR2032 coin-shaped batteries. The carbon cloth-supported iron oxide material (carbon cloth@Fe3O4@Co-MOFs), carbon cloth@Fe3O4 precursor, and Fe3O4 prepared in Example 1 were used as working electrodes (negative electrodes), and lithium foil was used as the counter electrode.

[0048] 2) Cut the two electrodes into 12 mm diameter discs, use Celgard 2400 as the separator, and add 1 M LiPF6 as the electrolyte in ethylene carbonate (EC) / diethyl carbonate (DEC) / dimethyl carbonate (DMC) (volume ratio of 1:1:1); the battery is assembled in an argon-filled glove box, and the H2O and O2 contents are kept below 0.1 ppm.

[0049] 3) Perform battery performance tests on the assembled lithium-ion batteries.

[0050] Figure 7 The results of the cycle performance test of the lithium-ion battery assembled using the carbon cloth-supported iron oxide material prepared in Example 1 as the negative electrode at a current of 1A / g show that the lithium-ion battery assembled using the carbon cloth@Fe3O4@Co-MOFs composite material prepared in Example 1 as the negative electrode has almost no capacity decay after 100 cycles at a current of 1A / g, and has a high specific capacity and very good cycle performance.

[0051] Figure 8 The results show the cycle performance of a lithium-ion battery assembled using the carbon cloth-supported iron oxide material prepared in Example 1 as the negative electrode at currents of 6 A / g and 10 A / g. Figure 8 (a) shows the cycling performance test results at a current of 6 A / g. Figure 8 (b) The cycling performance test results at a current of 10 A / g show that the device still exhibits high capacity after 500 and 1000 cycles at high currents of 6 A / g and 10 A / g, respectively, reaching 335 mAh g. -1 and 265mAh g-1 .

[0052] Figure 9 The graph shows the rate performance of lithium-ion batteries assembled using the carbon cloth-supported iron oxide material prepared in Example 1 as the negative electrode at different current densities. It can be seen that at current densities of 0.1 A / g, 0.3 A / g, 0.5 A / g, 1 A / g, 3 A / g, 5 A / g, and 10 A / g, the entire battery exhibits good rate performance, with reversible capacities of 1626, 1689, 1695, 1549, 1129, 754, and 372 mAh g, respectively. -1 The entire battery retained 99.5% of its capacity and had a cycle efficiency (CE) of approximately 100% after 100 cycles at 0.1 A / g, demonstrating excellent cycle stability. These results indicate that the carbon cloth@Fe3O4@Co-MOFs composite material has great potential for the fabrication of high-capacity and high-stability lithium-ion batteries.

[0053] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications made within the spirit and principle of the present invention are permitted.

Claims

1. A method for preparing a carbon cloth-supported iron oxide material, characterized in that, The steps include the following: S1. Soak the carbon cloth in nitric acid solution, take it out, wash it and vacuum dry it to obtain the pretreated carbon cloth; S2. Add ferric chloride hexahydrate and sodium acetate to ethylene glycol, stir and dissolve to obtain a mixed solution. Transfer the mixed solution to a stainless steel autoclave lined with polytetrafluoroethylene, put in the pretreated carbon cloth and seal it. Perform hydrothermal reaction at 170-190℃ for 10-16 hours. After the reaction is completed, take it out, wash it and obtain the precursor. S3. The precursor is immersed in a mixed solution of 2-methylimidazole and cobalt nitrate. After the immersion is completed, it is removed, cleaned, vacuum dried, and finally calcined at 400-600℃ under argon protection to obtain carbon cloth supported iron oxide material. In step S3, the soaking temperature is 80-90℃ and the soaking time is 10-15h. In the mixed solution of 2-methylimidazole and cobalt nitrate, the concentration of 2-methylimidazole is 4-6 mol / L and the concentration of cobalt nitrate is 1-2 mol / L.

2. The method for preparing carbon cloth-supported iron oxide material as described in claim 1, characterized in that, In step S1, the volume concentration of the nitric acid solution is 60%-70%.

3. The method for preparing carbon cloth-supported iron oxide material as described in claim 1, characterized in that, In step S1, the temperature of the vacuum drying is 80°C.

4. The method for preparing carbon cloth-supported iron oxide material as described in claim 1, characterized in that, In step S2, the molar ratio of ferric chloride hexahydrate to sodium acetate is 1:(2-2.5).

5. The method for preparing carbon cloth-supported iron oxide material as described in claim 1, characterized in that, In step S2, the hydrothermal reaction is carried out at a temperature of 180°C for 12 hours.

6. The method for preparing the carbon cloth-supported iron oxide material according to any one of claims 1 to 5, characterized in that, In step S3, the heating rate is 5℃ / min, the calcination temperature is 500℃, and the calcination time is 2h.

7. Carbon cloth-supported iron oxide material prepared by any one of claims 1 to 6.

8. The application of the carbon cloth-supported iron oxide material prepared by any one of claims 1 to 6 in the preparation of lithium-ion battery anodes.

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