A method for preparing gradient Ti-doped modified Fe2O3 as a negative electrode of a lithium ion battery

Abstract

The application belongs to the field of materials, and provides a method for preparing gradient Ti-doped modified Fe2O3 as a negative electrode of a lithium ion battery, which comprises the following steps: reacting a glucose solution at 160-180 DEG C for 4-6 h, performing solid-liquid separation after cooling, washing, drying the obtained precipitate at 60-70 DEG C for 10-12 h to obtain a carbon matrix template; dispersing the carbon matrix template into anhydrous ethanol to form a suspension; then adding iron nitrate and tetrabutyl titanate into the suspension, setting the concentration of Fe to be 2.5-2.8 M and the proportion of Ti to be 5-8%, continuously stirring for 2-4 h, collecting and drying to obtain a precursor; and performing heat treatment on the precursor. 3+ The reversible specific capacity of the gradient Ti-doped modified Fe2O3 as a negative electrode of a lithium ion battery can be maintained at 1001.9 mAh / g after 1200 cycles at a current density of 1 A / g, while the specific capacity of undoped Fe2O3 can only be maintained at 503.9 mAh / g after 1200 cycles at a current density of 1 A / g.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of materials, and particularly relates to a method for preparing a gradient Ti-doped modified Fe2O3 as a negative electrode of a lithium ion battery. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general background of the application and does not necessarily constitute an admission or a recognition that the information forms part of the prior art already known to a person of ordinary skill in the art.

[0003] Environmental deterioration and energy crisis have prompted countries around the world to pay more attention to energy security and environmental protection. The use of renewable energy is an important method to alleviate pollution of fossil energy and reduce greenhouse gas emissions. However, new renewable energy sources such as wind energy, solar energy, and tidal energy are limited by the uneven distribution of time and space. The development and use of safe and effective large-scale energy storage devices have become the key to alleviating energy problems. At the same time, the cruising range of new energy vehicles depends on the development of high-performance energy storage batteries.

[0004] However, as the most potential secondary energy storage battery at present, lithium ion batteries still cannot meet the needs of large-scale energy storage and large mobile terminal devices. The key to developing a new generation of lithium ion batteries lies in the development and use of high-performance electrode materials. Currently, commercial lithium ion batteries use graphite as the negative electrode, which has low theoretical capacity and poor rate performance.

[0005] Conversion-type Fe2O3 negative electrodes have the advantages of high theoretical capacity, environmental friendliness, and low price, and have become a strong competitor for the next generation of lithium ion battery negative electrodes. However, Fe2O3 has a low electrical conductivity and a large volume change during cycling, which restricts its further application. Currently, the methods to solve the above problems mainly include reducing particle size, carbon coating, and heteroatom doping. Reducing the particle size can effectively shorten the lithium ion diffusion path and improve the ion diffusion kinetics. However, the preparation of nanomaterials often involves high processing costs, poor volume energy density, and complex preparation processes. Therefore, the preparation of micron-level electrode materials that retain the properties of nanomaterials is a key to commercial application. In addition, although carbon coating can effectively improve the electrical conductivity of the electrode material, it often compromises part of the energy density.

[0006] Patent CN115057471A discloses a lithium ion battery negative electrode material and a preparation method thereof. Ti 4+ and Sn 4+ are quickly co-precipitated on the surface of carbon spheres by adding ammonia water, and a hollow structure is obtained after heat treatment. Although the hollow structure can provide a larger specific surface area, it is often complex to prepare, difficult to process, compromises the quality energy density, and is prone to side reactions. SUMMARY

[0007] In order to solve the above problems, the present application aims to obtain a micron-sized electrode material with nanomaterial properties by preparing a Ti gradient concentration doped Fe2O3, which is used as a negative electrode material of a lithium ion battery. Ti modifies the surface structure of the material, improves the lithium affinity of the active component, and improves the lithium ion diffusion kinetics. At the same time, as an unequal atomic replacement, Ti doping can jointly modulate the electronic structure through ion and electron compensation mechanisms.

[0008] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0009] In a first aspect of the present application, a method for modifying Fe2O3 with gradient Ti doping as a negative electrode of a lithium ion battery is provided, comprising:

[0010] The glucose solution is reacted at 160-180℃ for 4-6h, and after cooling, solid-liquid separation and washing, the obtained precipitate is dried at 60-70℃ for 10-12h to obtain a carbon matrix template;

[0011] The carbon matrix template is dispersed in anhydrous ethanol to form a suspension;

[0012] Then, iron nitrate and tetrabutyl titanate are added to the suspension, the concentration of Fe is set to 2.5-2.8M, the proportion of Ti is 5-8%, and stirring is continued for 2-4h, and the precursor is collected and dried; 3+

[0013] The precursor is subjected to heat treatment, and the gradient Ti doped Fe2O3 is obtained.

[0014] Heteroatomic doping and its charge compensation mechanism is one of the important ways to modulate electrode materials. The present application finds that Ti gradient concentration doped Fe2O3 modifies the surface structure to obtain a micron-sized electrode material with nanomaterial properties, which effectively improves its performance.

[0015] In a second aspect of the present application, the gradient Ti doped Fe2O3 prepared by the above method is provided as a negative electrode of a lithium ion battery.

[0016] In a third aspect of the present application, the gradient Ti doped Fe2O3 as a negative electrode of a lithium ion battery is provided for use in the preparation of energy storage batteries, new energy vehicles, and large mobile terminal devices.

[0017] Advantages of the present application

[0018] ​(1) The application prepares a Ti gradient concentration doped Fe2O3 electrode, which can still maintain a reversible specific capacity of 1001.9 mAh / g after 1200 cycles at a current density of 1 A / g as a negative electrode of a lithium ion battery, and the undoped Fe2O3 can only maintain a specific capacity of 503.9 mAh / g after 1200 cycles at a current density of 1 A / g.

[0019] (2) Compared with patent CN115057471A, in the application, Fe 3+ and Ti 4+ ions are adsorbed to the carbon matrix through electrostatic adsorption, slowly infiltrate into the carbon matrix under the low surface tension of alcohol, and obtain solid nanoparticles, as shown in Figure 3 The prepared solid nanoparticles can avoid the loss of mass energy density as much as possible, and also retain the electrochemical properties comparable to nanomaterials, and are closer to actual application.

[0020] (3) The general doping is uniformly distributed in the Fe2O3 crystal structure, and in the application, the gradient means that the doping concentration of Ti is different from the surface of the material to the inside (gradually decreasing from the surface to the bulk). The application utilizes the concentration difference of Fe 3+ and Ti 4+ , and when infiltrating the carbon particles, Fe 3+ with high concentration can fully infiltrate the entire matrix, and Ti 4+ with low concentration can only infiltrate the surface of several tens of nanometers, thereby forming a gradient doping, effectively improving the reversible specific capacity and cycle performance of the electrode material.

[0021] (4) The preparation method of the application is simple, practical, and easy to popularize. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings accompanying the specification of the application form a part of the application and serve to further understand the application. The exemplary embodiments of the application and the description thereof are used to explain the application, and do not constitute an improper limitation on the application.

[0023] Figure 1 The scanning diagram of the gradient Ti modified Fe2O3 prepared in Example 1 of the application;

[0024] Figure 2 The charge-discharge curve of the 1200th cycle of Fe2O3 and Ti-Fe2O3 prepared in Example 1 of the application.

[0025] Figure 3 The transmission electron microscope picture of the gradient Ti modified Fe2O3 prepared in Example 1 of the application.

[0026] Figure 4 The diagram of the relative content of Ti element of Ti modified Fe2O3 and etching depth. Detailed Implementation

[0027] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] A method for using gradient Ti-doped Fe2O3 as a lithium-ion battery anode includes:

[0029] The glucose solution was reacted at 160–180 °C for 4–6 h, cooled, and then the solid and liquid were separated and washed. The obtained precipitate was dried at 60–70 °C for 10–12 h to obtain a carbon matrix template.

[0030] The carbon template matrix was dispersed in anhydrous ethanol to form a suspension;

[0031] Subsequently, ferric nitrate and tetrabutyl titanate were added to the suspension, setting the Fe... 3+ The concentration of the precursor was 2.5–2.8 M, the proportion of Ti was 5–8%, and the mixture was stirred continuously for 2–4 h. The precursor was then collected, dried, and obtained.

[0032] The precursor is then subjected to heat treatment to obtain the final product.

[0033] In some embodiments, the concentration of the glucose solution is 0.5–0.6 M.

[0034] In some embodiments, the solvent for the glucose solution is deionized water.

[0035] In some embodiments, the glucose solution is reacted in a reaction vessel lined with polytetrafluoroethylene.

[0036] In some embodiments, the solid-liquid separation is performed by centrifugation.

[0037] In some embodiments, the carbon template matrix is ​​washed with alcohol and water, and the Ti-doped sample is washed with alcohol.

[0038] In some embodiments, the concentration of the suspension is 20–30 mg / ml.

[0039] In some embodiments, the heat treatment conditions are: heat treatment in air at 550–600°C for 1–1.5 hours.

[0040] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0041] Example 1

[0042] A gradient Ti-doped Fe2O3 electrode as a lithium ion battery anode, mainly comprising the following steps:

[0043] (I) Preparation of carbon matrix template

[0044] (1) Dissolve an appropriate amount of glucose in 40 mL of deionized water to form a 0.5 M solution.

[0045] (2) Transfer the solution prepared in step (1) to a polytetrafluoroethylene-lined reaction kettle and react at 160°C for 6h.

[0046] (3) After sufficient cooling, centrifugal washing with alcohol and deionized water several times, the obtained precipitate is dried at 60°C for 12h.

[0047] (II) Preparation of Ti gradient concentration modified Fe2O3

[0048] (1) 600 mg of the carbon template matrix prepared in (I) is dispersed in 30 ml of anhydrous ethanol to form a suspension, and then iron nitrate and tetrabutyl titanate are added to the solution. The concentration of Fe is set to 2.5 M, and the proportion of Ti is about 6%. Stir for 2h, and collect the dried product. 3+

[0049] (2) Heat the above precursor at 550°C for 1h under air.

[0050] The above material can still maintain a reversible specific capacity of 1001.9 mAh / g as a lithium ion battery anode after 1200 cycles at a current density of 1A / g, while undoped Fe2O3 can only maintain a specific capacity of 503.9 mAh / g after 1200 cycles at a current density of 1A / g.

[0051] Example 2

[0052] A gradient Ti-doped Fe2O3 electrode as a lithium ion battery anode, mainly comprising the following steps:

[0053] (I) Preparation of carbon matrix template

[0054] (1) Dissolve an appropriate amount of glucose in 40 mL of deionized water to form a 0.6 M solution.

[0055] (2) Transfer the solution prepared in step (1) to a polytetrafluoroethylene-lined reaction kettle and react at 180°C for 4h.

[0056] (3) After sufficient cooling, centrifugal washing with alcohol and deionized water several times, the obtained precipitate is dried at 70°C for 10h.

[0057] (II) Preparation of Ti gradient concentration modified Fe2O3 ​

[0058] (1) 600 mg of the carbon template matrix prepared in (1) was dispersed in 20 ml of anhydrous ethanol to form a suspension, and then iron nitrate and tetrabutyl titanate were added to the solution. The concentration of Fe was set to 2.8 M, and the proportion of Ti was about 5%. Stirring was continued for 4 h, and drying was collected. 3+

[0059] (2) The above precursor was heat-treated at 600°C for 1.5 h in air.

[0060] Example 3

[0061] A gradient Ti-doped Fe2O3 electrode as a negative electrode of a lithium ion battery mainly includes the following steps:

[0062] (1) Preparation of a carbon matrix template

[0063] (1) A proper amount of glucose was dissolved in 40 mL of deionized water to prepare a 0.55 M solution.

[0064] (2) The solution prepared in step (1) was transferred to a polytetrafluoroethylene-lined reaction kettle, and reacted at 170°C for 5 h.

[0065] (3) After sufficient cooling, centrifugation was performed, and the obtained precipitate was repeatedly washed with alcohol and deionized water several times, and then dried at 65°C for 11 h.

[0066] (2) Preparation of Ti gradient concentration modified Fe2O3

[0067] (1) 600 mg of the carbon template matrix prepared in (1) was dispersed in 25 ml of anhydrous ethanol to form a suspension, and then iron nitrate and tetrabutyl titanate were added to the solution. The concentration of Fe was set to 2.65 M, and the proportion of Ti was about 8%. Stirring was continued for 3 h, and drying was collected. 3+

[0068] (2) The above precursor was heat-treated at 580°C for 1.2 h in air.

[0069] Comparative Example 1

[0070] Journal of Alloys and Compounds 924 (2022) 166441, which can only maintain 760 mAh g -1 at a current density of 1A g -1 .

[0071] ​​The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A method for gradient Ti-doped Fe2O3 as a lithium-ion battery anode, characterized in that, include: The glucose solution was reacted at 160–180 °C for 4–6 h, cooled, and then the solid and liquid were separated and washed. The obtained precipitate was dried at 60–70 °C for 10–12 h to obtain a carbon matrix template. The carbon matrix template was dispersed in anhydrous ethanol to form a suspension; Subsequently, ferric nitrate and tetrabutyl titanate were added to the suspension, setting the Fe... 3+ The concentration of the precursor was 2.5–2.8 M, the proportion of Ti was 5–8%, and the mixture was stirred continuously for 2–4 h. The precursor was then collected, dried, and obtained. The precursor is then subjected to heat treatment to obtain the final product.

2. The method for using gradient Ti-doped Fe2O3 as a lithium-ion battery anode as described in claim 1, characterized in that, The concentration of the glucose solution is 0.5–0.6 M.

3. The method for using gradient Ti-doped Fe2O3 as a lithium-ion battery anode as described in claim 1, characterized in that, The solvent for the glucose solution is deionized water.

4. The method for using gradient Ti-doped Fe2O3 as a lithium-ion battery anode as described in claim 1, characterized in that, The glucose solution was reacted in a reaction vessel lined with polytetrafluoroethylene.

5. The method for using gradient Ti-doped Fe2O3 as a lithium-ion battery anode as described in claim 1, characterized in that, The solid-liquid separation method is centrifugation.

6. The method for using gradient Ti-doped Fe2O3 as a lithium-ion battery anode as described in claim 1, characterized in that, When preparing the carbon template matrix, it is washed with alcohol and water; when preparing the Ti-doped sample, it is washed with alcohol.

7. The method for using gradient Ti-doped Fe2O3 as a lithium-ion battery anode as described in claim 1, characterized in that, The concentration of the suspension is 20–30 mg / ml.

8. The method for using gradient Ti-doped Fe2O3 as a lithium-ion battery anode as described in claim 1, characterized in that, The heat treatment conditions are: in air, heat treatment at 550-600℃ for 1-1.5 hours.

9. The gradient Ti-doped Fe2O3 prepared by the method according to any one of claims 1-8 is used as the negative electrode of a lithium-ion battery.

10. The application of the gradient Ti-doped Fe2O3 as a lithium-ion battery anode in the preparation of energy storage batteries, new energy vehicles, and large mobile terminal devices, as described in claim 9.

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