阅读说明：本技术 一种碳掺杂三明治结构锂离子电池负极材料的制备方法 (Preparation method of carbon-doped sandwich-structure lithium ion battery cathode material ) 是由 吕晓欣 邓子啸 邓久军 王梦莲 于 2021-07-28 设计创作，主要内容包括：本发明提供了一种锂离子电池负极材料的制备方法,具体为一种碳掺杂三明治结构纳米TiO-(2)@Fe-(2)O-(3)锂离子电池负极材料的制备方法。针对目前TiO-(2)负极材料比容量不高和电导率低的缺点,本发明以Ti-(3)C-(2)和二茂铁作为前驱体,通过一步退火处理制备出了碳掺杂三明治结构纳米TiO-(2)@Fe-(2)O-(3)复合物,其优点在于合成工艺简单、成本低、可以大规模生产。此方法制备的碳掺杂三明治结构纳米TiO-(2)@Fe-(2)O-(3)颗粒均匀,具有良好的电化学性能。(The invention provides a preparation method of a lithium ion battery cathode material, and particularly relates to a carbon-doped sandwich structure nano TiO 2 @Fe 2 O 3 A preparation method of a lithium ion battery cathode material. Aiming at the existing TiO 2 The negative electrode material has the defects of low specific capacity and low conductivity, and the invention uses Ti 3 C 2 And ferrocene as a precursor, and preparing the carbon-doped sandwich structure nano TiO by one-step annealing treatment 2 @Fe 2 O 3 The compound has the advantages of simple synthesis process, low cost and large-scale production. The carbon-doped sandwich-structure nano TiO prepared by the method 2 @Fe 2 O 3 The particles are uniform and have good electrochemical performance.)

1. A preparation method of a carbon-doped sandwich structure lithium ion battery cathode material is characterized by comprising the following specific steps:

the first step is as follows: weighing ferrocene and multilayer Ti₃C₂Placing the powder into a mortar, and grindingGrinding uniformly;

the second step is that: placing the ground mixture into a porcelain boat, tightly wrapping the porcelain boat by using an aluminum foil, then placing the whole porcelain boat into a tube furnace, and carrying out annealing treatment for a certain time to obtain the carbon-doped nano TiO with the sandwich structure₂@Fe₂O₃A material.

2. The method for preparing the carbon-doped sandwich-structure lithium ion battery cathode material of claim 1, wherein in the first step, ferrocene and multiple layers of Ti are added₃C₂The mass ratio of the powder is 1: 5-6: 1.

3. The method for preparing the carbon-doped sandwich-structure lithium ion battery cathode material of claim 2, wherein in the first step, ferrocene and multiple layers of Ti are added₃C₂The mass ratio of the powders was 4: 1.

4. The method for preparing the carbon-doped sandwich structure lithium ion battery cathode material of claim 1, wherein in the second step, the annealing temperature is 300-500 ℃ and the annealing time is 1-3 hours.

Technical Field

The invention provides a lithium ionA preparation method of a battery cathode material, in particular to a carbon-doped sandwich structure nano TiO₂@Fe₂O₃A preparation method of a lithium ion battery cathode material.

Background

Lithium ion batteries have been widely used in portable electronic devices due to their high energy density, long cycle life, low self-discharge rate, no memory effect, and the like.

The cathode material is used as an important component of the lithium ion battery, and the structure and the composition of the cathode material greatly influence the electrochemical performance of the lithium ion battery. The traditional commercialized negative electrode material is graphitized carbon, and the lower theoretical specific capacity (372mAh/g) of the graphitized carbon cannot meet the requirements of new-generation mobile devices and power batteries. TiO 2₂Due to its low cost, environmental friendliness, etc., it is considered to be one of the most potential negative electrode materials that can replace graphite, and therefore has received increasing attention. And the characteristic of small volume change in the charge-discharge process of the TiO compound enables the TiO compound to be small in volume change₂The lithium ion battery has excellent structural stability and better cycling stability in the processes of lithium ion intercalation and deintercalation. However, TiO₂The lower theoretical specific capacity and poor conductivity limit its application in lithium ion batteries. There are two common solutions at present, one is to increase the specific capacity of a metal oxide with a higher theoretical specific capacity by forming a composite material with the metal oxide; and the other is that the conductivity of the lithium-ion battery can be improved by doping C, N, Fe and other exogenous atoms, so that the lithium-ion storage performance of the lithium-ion battery is improved.

Most of the existing carbon doping methods need an external carbon source and are realized by sol-gel, hydrothermal and other methods, the preparation process is complex, and the equipment cost and the production cost are too high. MXene is a novel two-dimensional transition metal carbide or nitride, and the high conductivity and the unique structure of MXene enable the MXene to be widely applied to the field of electrochemistry. Among various MXene materials, Ti has abundant surface properties and excellent structural stability₃C₂Have received increasing attention. Ti₃C₂Can be oxidized into TiO under certain conditions₂And in the formation of TiO₂In the process, Ti₃C₂C in (3) can be doped into TiO as a suitable dopant₂Increasing the TiO content₂The conductivity is realized, and no additional carbon dopant is added. The invention is to directly oxidize multi-layer Ti₃C₂Powder, without additional carbon source, to obtain carbon-doped layered TiO₂。

At the same time, Fe₂O₃The lithium ion battery has the characteristics of high theoretical specific capacity (1005mAh/g), environmental friendliness, low cost and the like, but the electrode material is pulverized and falls off due to severe volume expansion in the circulation process, the capacity is rapidly attenuated, and the application of the lithium ion battery in the lithium ion battery is hindered. To react it with TiO₂Compounding, not only can improve the specific capacity of the compound, but also can relieve Fe to a certain extent₂O₃The volume changes. The traditional compound generally needs more complex synthetic steps, and the preparation process is complex and not easy to obtain.

The invention uses Ti₃C₂And ferrocene as a precursor, and preparing the carbon-doped sandwich structure nano TiO by a one-step method₂@Fe₂O₃And (c) a complex. The preparation method is simple and easy to operate, and the prepared compound has a sandwich structure with the advantages of large specific surface area and high reaction activity, and is convenient for migration of lithium ions and electrons. Carbon doped layered TiO in composites₂The zero-strain characteristic can provide excellent stability for the compound and relieve Fe to a certain extent₂O₃Volume expansion during cycling. Fe in the composite₂O₃The nano particles can provide high specific capacity for the compound, and finally the capacity and the stability of the compound are improved.

Disclosure of Invention

The invention aims to provide carbon-doped sandwich-structured nano TiO with simple process, low production cost and convenient large-scale application₂@Fe₂O₃A preparation method of a lithium ion battery cathode material.

In order to achieve the aim of the invention, the method specifically comprises the following steps:

the first step is as follows: weighing ferrocene andmultilayer Ti₃C₂(Mxene) powder, put into mortar, grind;

the second step is that: placing the ground mixture into a porcelain boat, tightly wrapping the porcelain boat by using an aluminum foil, then placing the whole porcelain boat into a tube furnace, and carrying out annealing treatment for a certain time to obtain the carbon-doped nano TiO with the sandwich structure₂@Fe₂O₃A material;

further, the above-mentioned preparation method, in the first step, ferrocene and multi-layered Ti₃C₂The mass ratio of the powder is 1: 5-6: 1.

In the second step of the preparation method, the annealing temperature is 300-500 ℃, and the annealing time is 1-3 hours.

Aiming at the existing TiO₂The negative electrode material has the defects of low specific capacity and low conductivity, and the invention uses Ti₃C₂And ferrocene as a precursor, and preparing the carbon-doped sandwich structure nano TiO by one-step annealing treatment₂@Fe₂O₃The compound has the advantages of simple synthesis process, low cost and large-scale production. The carbon-doped sandwich-structure nano TiO prepared by the method₂@Fe₂O₃The particles are uniform and have good electrochemical performance.

Drawings

FIG. 1 shows the preparation of carbon-doped nano TiO with sandwich structure by the method of the present invention₂@Fe₂O₃Reaction scheme of lithium battery negative electrode material.

FIG. 2(a) is a scanning electron micrograph of the product prepared in example 1 of the process of the present invention.

FIG. 2(b) is a graph of the circulating capacity of the product obtained in example 1 of the process of the invention.

FIG. 3(a) is a scanning electron micrograph of the product prepared in example 2 of the present invention.

FIG. 3(b) is a graph of the circulating capacity of the product obtained in example 2 of the process of the present invention.

FIG. 4(a) is a scanning electron micrograph of the product prepared in example 3 of the process of the present invention.

FIG. 4(b) is a graph of the circulating capacity of the product obtained in example 3 of the process of the present invention.

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but not to limit the present invention.

Example 1

(1) Weighing a certain amount of ferrocene powder and Ti with the mass ratio of 1:5₃C₂Putting the powder into an agate mortar, and uniformly grinding;

(2) placing the ground mixture in a porcelain boat, tightly wrapping the porcelain boat with aluminum foil, placing the porcelain boat in a tube furnace, and annealing at 450 ℃ for 2 hours to obtain the carbon-doped sandwich structure nano TiO₂@Fe₂O₃The negative electrode material (FIG. 2(a)) was obtained by doping TiO with carbon₂Well maintain Ti₃C₂Of a layered structure of, and Fe₂O₃The particles are uniformly dispersed in the layered TiO₂And the surface to form a sandwich structure;

(3) respectively weighing carbon-doped sandwich structure nano TiO according to the mass ratio of 70:20:10₂@Fe₂O₃The composite, conductive carbon black and polyvinylidene fluoride (PVDF) are put in an agate mortar, solvent N-methyl pyrrolidone (NMP) is added and evenly ground. The obtained slurry was coated on the surface of a clean copper foil, and dried in a vacuum drying oven for 12 hours. Cutting the dried copper foil into a circular sheet with the diameter of 12mm by a manual slicer to be used as an electrode pole piece, taking metal lithium as a counter electrode and 1mol/L LiPF₆and/DMC + DEC + EC (the volume ratio of DMC, DEC and EC is 1:1:1) is used as electrolyte, and Celgard 2325 is used as a diaphragm to form the button test cell. The battery is subjected to constant-current charge and discharge tests, the charge and discharge voltage range is 0.01-3.0V, and the result shows that the battery has better electrochemical performance, when the test current density is 1000mA/g, the first discharge specific capacity is 225.6mAh/g, and the discharge specific capacity after 400 cycles is 136mAh/g (fig. 2 (b)).

Example 2

(1) Weighing a certain amount of ferrocene powder and Ti with the mass ratio of 4:1₃C₂Placing the powder in an agate mortarAnd grinding uniformly;

(2) placing the ground ferrocene into a porcelain boat, tightly wrapping the porcelain boat by using aluminum foil, placing the porcelain boat into a tube furnace, and annealing at 450 ℃ for 2 hours to obtain carbon-doped sandwich structure nano TiO₂@Fe₂O₃The negative electrode material (FIG. 3(a)) was obtained by the present example, and the carbon-doped TiO was observed in the drawing₂Also well maintain Ti₃C₂Of a layered structure of, Fe₂O₃The particle size and the density are increased to a certain degree, and the particles are uniformly dispersed in the layered TiO₂And the surface, a very obvious sandwich structure is formed;

(3) respectively weighing sandwich structure nano TiO according to the mass ratio of 70:20:10₂@Fe₂O₃The composite, conductive carbon black and polyvinylidene fluoride (PVDF) are put in an agate mortar, solvent N-methyl pyrrolidone (NMP) is added and evenly ground. The obtained slurry was coated on the surface of a clean copper foil, and dried in a vacuum drying oven for 12 hours. Cutting the dried copper foil into a circular sheet with the diameter of 12mm by a manual slicer to be used as an electrode pole piece, taking metal lithium as a counter electrode and 1mol/L LiPF₆and/DMC + DEC + EC (the volume ratio of DMC, DEC and EC is 1:1:1) is used as electrolyte, and Celgard 2325 is used as a diaphragm to form the button test cell. When the current density is 1000mA/g, the discharge specific capacity after 900 cycles is 403.3mAh/g, and the capacity retention rate is up to 92% (fig. 3 (b)). The better capacity retention rate is attributed to the ferrocene and Ti in the precursor₃C₂The mass ratio of the powder is proper. And ferrocene and Ti₃C₂An excessively small mass proportion of powder results in Fe in the resulting composite₂O₃The occupied proportion is too small, so that the specific capacity of the composite negative electrode is not obviously improved; and ferrocene and Ti₃C₂An excessive powder mass ratio will result in Fe in the resulting composite₂O₃The nano particles are agglomerated and grow up, and further the negative cycle stability of the compound is reduced. Thus, ferrocene and Ti are suitable₃C₂Mass ratio of powderFor example, the effect on the electrochemical performance of the battery is particularly important.

Example 3

(1) Weighing a certain amount of ferrocene powder and Ti with the mass ratio of 6:1₃C₂Putting the powder into an agate mortar, and uniformly grinding;

(2) placing the ground ferrocene into a porcelain boat, tightly wrapping the porcelain boat by using aluminum foil, placing the porcelain boat into a tube furnace, and annealing at 450 ℃ for 2 hours to obtain carbon-doped sandwich structure nano TiO₂@Fe₂O₃The negative electrode material (FIG. 4(a)) was obtained by the present example, and the carbon-doped TiO was observed in the drawing₂Also well maintain Ti₃C₂Of a layered structure of, Fe₂O₃The particle size and density are increased and are uniformly dispersed in the layered TiO₂And the surface to form a very obvious sandwich structure;

(3) respectively weighing sandwich structure nano TiO according to the mass ratio of 70:20:10₂@Fe₂O₃The composite, conductive carbon black and polyvinylidene fluoride (PVDF) are put in an agate mortar, solvent N-methyl pyrrolidone (NMP) is added and evenly ground. The obtained slurry was coated on the surface of a clean copper foil, and dried in a vacuum drying oven for 12 hours. Cutting the dried copper foil into a circular sheet with the diameter of 12mm by a manual slicer to be used as an electrode pole piece, taking metal lithium as a counter electrode and 1mol/L LiPF₆and/DMC + DEC + EC (the volume ratio of DMC, DEC and EC is 1:1:1) is used as electrolyte, and Celgard 2325 is used as a diaphragm to form the button test cell. The battery is subjected to constant-current charge and discharge tests, the charge and discharge voltage range is 0.01-3.0V, and the result shows that the battery has better electrochemical performance, when the test current density is 1000mA/g, the first discharge specific capacity is 422.3mAh/g, and the discharge specific capacity after 900 cycles is 270.3mAh/g (fig. 4 (b)).