阅读说明：本技术 一种层状结构钛酸锂纳米颗粒的制备方法 (Preparation method of lithium titanate nanoparticles with layered structure ) 是由 唐煌 薛建忠 吴晓庆 方涛 左旭东 于 2020-11-02 设计创作，主要内容包括：本发明提供了一种层状结构钛酸锂纳米颗粒的制备方法,包括：用酸性溶液腐蚀Ti3AlC2,生成二维材料MXene,再以MXene为前躯体,水热后再氧化两步法合成层状堆积的二氧化钛纳米颗粒,最后利用层状堆积的二氧化钛与碳酸锂在惰性气氛下高温反应,合成出层状结构的钛酸锂,其纳米颗粒尺寸大小在100nm左右,规则地以二维层状形式堆积。该材料作为锂离子电极材料,表现出优秀的长循环稳定性。(The invention provides a preparation method of lithium titanate nanoparticles with a layered structure, which comprises the following steps: corroding Ti3AlC2 with an acidic solution to generate a two-dimensional material MXene, then using the MXene as a precursor, hydrothermally oxidizing the precursor to synthesize titanium dioxide nano particles stacked in a layered manner, and finally utilizing the high-temperature reaction of the titanium dioxide stacked in the layered manner and lithium carbonate in an inert atmosphere to synthesize lithium titanate with a layered structure, wherein the size of the nano particles is about 100nm, and the lithium titanate is regularly stacked in a two-dimensional layered manner. The material is used as a lithium ion electrode material and shows excellent long-cycle stability.)

1. A preparation method of lithium titanate nanoparticles with a layered structure is characterized by specifically comprising the following steps: step one, adding Ti3AlC2 into an acid solution, and stirring magnetons until complete reaction; secondly, obtaining a layered material MXene by centrifugally washing and vacuum drying a reaction product; and thirdly, carrying out hydrothermal treatment on the obtained MXene under a certain condition, carrying out centrifugal washing and drying, then oxidizing in air or oxygen to obtain titanium dioxide nano particles stacked in a layered manner, mixing the titanium dioxide stacked in the layered manner with lithium carbonate according to a reaction ratio, uniformly grinding, and carrying out high-temperature reaction in an inert atmosphere to finally generate the lithium titanate nano particles with the layered structure.

2. The method according to claim 1, wherein the acidic solution can be hydrochloric acid, sulfuric acid, nitric acid or hydrofluoric acid, the concentration of the acidic solution is 10-60%, and the mass ratio of the Ti3AlC2 to the acidic solution is 1: 3-1: 20.

3. The method of claim 1, wherein the rotation speed of the magneton stirring is 100-800 rpm, and the stirring time is 2-50 hours.

4. The method according to claim 1, wherein the rotation speed of the centrifugal washing is 1000-10000 r/min, the centrifugal washing is carried out until the pH value is 5-7, the temperature of the vacuum drying is 50-120 ℃, and the drying time is 5-24 hours.

5. The method according to claim 1, characterized in that the temperature of the hydrothermal reaction is used: the hydrothermal time is 1-48 hours, the mass ratio of MXene to deionized water is 1: 10-1: 200 at 100-250 ℃.

6. The method according to claim 1, wherein the atmosphere in which the oxidation reaction is carried out is air or oxygen, and the temperature: the oxidation time is 1-48 hours at 100-500 ℃.

7. The method of claim 1, wherein the inert atmosphere for the high temperature reaction is nitrogen or argon, the temperature is 700-1100 ℃, and the reaction time is 6-12 hours.

8. A layered structure lithium titanate nanoparticle prepared by the method of claim 1, wherein the lithium titanate nanoparticle has a size of 90 to 110nm and is regularly shaped and regularly layered.

Technical Field

The invention relates to preparation of a nano material, in particular to a preparation method of lithium titanate nano particles with a layered structure.

Background

Lithium titanate (Li4Ti5O12) is a composite oxide of metallic lithium and a low-potential transition metal titanium, belonging to the AB2X4 series, and can be described as a spinel solid solution. The lithium titanate material has the characteristics of stable structure, environmental friendliness, convenience in preparation and low price, and has zero strain property. The zero strain property means that the crystal has small lattice constant and volume change when lithium ions are inserted or removed, and the zero strain property can avoid the structural damage caused by the back-and-forth expansion of an electrode material in the charge-discharge cycle, thereby improving the cycle performance and the service life of the electrode, reducing the specific capacity attenuation caused by the cycle, and having very good overcharge and overdischarge resistance characteristics. However, in the aspect of lithium battery application, the electrochemical performance of the lithium battery is greatly related to the particle size and the micro-morphology of lithium titanate. The reduction of the particle size can shorten the diffusion path of lithium ions, facilitate charge transmission and improve the performance of the lithium battery. Therefore, lithium titanate with different morphologies and nano structures is being researched as a new electrode material, such as lithium titanate nanosheets, lithium titanate nanorods, lithium titanate nanospheres, and the like.

In recent years, MXene, a novel layered material, is attracting attention. The precursor for preparing MXene is MAX phase, a ternary layered material integrating the excellent characteristics of ceramic and metal, and a novel two-dimensional layered material MXene is obtained by selectively corroding the element A in the ternary layered material through an acidic solution. The material shows good electrochemical performance, and can obtain high-capacity specific capacitance when being used as an electrode of a super capacitor. But the performance of the lithium ion battery is general as a negative electrode material of the lithium ion battery. Therefore, MXene is taken as a precursor, anatase titanium dioxide nanoparticles with a layered structure are successfully prepared through a hydrothermal and reoxidation two-step method, and finally titanium dioxide stacked in a layered manner and lithium carbonate are subjected to high-temperature reaction in an inert atmosphere to generate nano lithium titanate particles stacked in a layered manner. The lithium titanate nanoparticles have a size of about 100nm, are regularly stacked in a two-dimensional layered form, and exhibit excellent electrochemical properties.

Disclosure of Invention

The invention aims to provide a preparation method of lithium titanate nanoparticles with a layered structure aiming at the defects of the prior art.

The technical scheme for solving the problems comprises the following steps: a preparation method of lithium titanate nanoparticles with a layered structure specifically comprises the following steps: step one, adding Ti3AlC2 into an acid solution, and stirring magnetons until complete reaction; secondly, obtaining a layered material MXene by centrifugally washing and vacuum drying a reaction product; and thirdly, carrying out hydrothermal treatment on the obtained MXene under a certain condition, carrying out centrifugal washing and drying, then oxidizing in air or oxygen to obtain titanium dioxide nano particles stacked in a layered manner, mixing the titanium dioxide stacked in the layered manner with lithium carbonate according to a reaction ratio, uniformly grinding, and carrying out high-temperature reaction in an inert atmosphere to finally generate the lithium titanate nano particles with the layered structure.

Furthermore, the acid solution can be hydrochloric acid, sulfuric acid, nitric acid or hydrofluoric acid, the concentration of the acid solution is 10-60%, and the mass ratio of the Ti3AlC2 to the acid solution is 1: 3-1: 20.

Furthermore, the rotating speed of the magnetic stirring is 100-800 r/min, and the stirring time is 2-50 hours.

Further, the rotating speed of centrifugal washing is 1000-10000 r/min, the centrifugal washing is carried out until the pH value is 5-7, the temperature of vacuum drying is 50-120 ℃, and the drying time is 5-24 hours.

Further, the temperature of the hydrothermal reaction is: the hydrothermal time is 1-48 hours, the mass ratio of MXene to deionized water is 1: 10-1: 200 at 100-250 ℃.

Further, the atmosphere of the oxidation reaction is air or oxygen, and the temperature is as follows: the oxidation time is 1-48 hours at 100-500 ℃.

Further, the inert atmosphere of the high-temperature reaction is nitrogen or argon, the temperature is 700-1100 ℃, and the reaction time is 6-12 hours.

Furthermore, the size of the lithium titanate nano-particles is 90-110nm, the shape is regular, and the lithium titanate nano-particles are regularly stacked in a layered manner.

The invention has the following beneficial effects:

the invention provides a preparation method of lithium titanate nanoparticles with a layered structure, which comprises the steps of using a novel two-dimensional material MXene as a template, synthesizing titanium dioxide nanoparticles stacked in a layered manner by a hydrothermal post-oxidation two-step method, and reacting the titanium dioxide nanoparticles stacked in a layered manner with lithium carbonate at a high temperature to generate lithium titanate nanoparticles with a layered structure. At present, almost no report exists on lithium titanate with a layered structure, and lithium titanate nano particles prepared by the method are small and only about 100 nanometers, are regularly and stratically stacked, are convenient for the intercalation and deintercalation of lithium ions, and show excellent electrochemical performance.

Drawings

Fig. 1 is an XRD pattern of layered structure lithium titanate nanoparticles prepared in a preferred embodiment of the present invention;

fig. 2 is an SEM image of the layered structure lithium titanate nanoparticles prepared in the preferred embodiment of the present invention.

Detailed Description

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.

Example 1:

1. adding 1g of Ti3AlC2 into 10ml of 40% hydrofluoric acid, and stirring for 24 hours by magnetons;

2. centrifuging and washing the stirred solution until the pH value is 6, performing vacuum drying for 60 hours, and drying for 12 hours to obtain a two-dimensional material MXene;

3. adding 0.2g of MXene into 20ml of deionized water, carrying out hydrothermal treatment at 200 ℃ for 5 hours, carrying out centrifugal washing until the pH value is 7, carrying out vacuum washing at 60 ℃, and drying for 12 hours;

4. and (3) putting the dried product into a muffle furnace, and oxidizing at 300 ℃ for 3 hours to obtain the product which is the titanium dioxide nano-particles stacked in a layered mode.

5. And grinding the titanium dioxide and 0.1g of lithium titanate which are stacked in a layered manner and obtained by the reaction for 10 minutes, uniformly mixing the titanium dioxide and the lithium titanate, putting the mixture into a tubular furnace, introducing high-purity argon, and reacting at 800 ℃ for 9 hours to obtain the product, namely the lithium titanate nano-particles with the layered structure.

Referring to fig. 1, which is an XRD spectrum of the lithium titanate nanoparticles with a layered structure provided in this embodiment, it can be seen from the graph that, in comparison with the standard card JCPDS No.49-0207, XRD diffraction peaks completely correspond to the standard spectrum of lithium titanate, and 9 diffraction peaks respectively correspond to the diffraction peaks of the (111), (311), (400), (331), (333), (440), (531), (533), and (622) crystal planes of lithium titanate.

See fig. 2, which is an SEM image of lithium titanate nanoparticles provided in this example. As can be seen from the scanning electron microscope image, the lithium titanate nanoparticles are typically stacked in layers, and the particle size is about 100 nanometers.

The above description is only a preferred embodiment of the present invention, and not intended to limit the present invention in other forms, and any person skilled in the art may apply the above modifications or changes to the equivalent embodiments with equivalent changes, without departing from the technical spirit of the present invention, and any simple modification, equivalent change and change made to the above embodiments according to the technical spirit of the present invention still belong to the protection scope of the technical spirit of the present invention.