CN113087011A

CN113087011A - Titanium dioxide B-phase material and preparation method and application thereof

Info

Publication number: CN113087011A
Application number: CN202110347484.7A
Authority: CN
Inventors: 魏明灯; 杨程宇
Original assignee: Fuzhou University
Current assignee: Fuzhou University
Priority date: 2021-03-31
Filing date: 2021-03-31
Publication date: 2021-07-09

Abstract

The invention discloses a titanium dioxide B phase material and a preparation method and application thereof, wherein (101) titanium dioxide B phase material with an exposed crystal face is successfully designed and synthesized for the first time, ammonium fluotitanate is used as a titanium source, glycolic acid is used as a reaction environment, a titanium dioxide precursor is synthesized through simple hydrothermal reaction, and then the titanium dioxide precursor is calcined in a muffle furnace to obtain a pure phase titanium dioxide B phase material with high crystallinity, so that the structural stability of the material is improved. Meanwhile, the special (101) exposed crystal face structure of the material provides more active sites for lithium, and ion combination and transmission are facilitated. The prepared soft package full battery has high specific capacity and good cycling stability, and the capacity can still reach 46.6mAh/g after 1000 cycles when the current density is 10C (1C =325 mAh/g).

Description

Titanium dioxide B-phase material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of soft package full-cell cathode materials, and particularly relates to a titanium dioxide B-phase material and a preparation method and application thereof.

Background

The titanium-based material mainly adopts titanates such as lithium titanate and the like as the soft package full-cell negative electrode material, and related patent reports that a titanium dioxide B-phase material is used as the soft package full-cell negative electrode material are also found at present.

Because of the high energy density, the lithium battery is widely applied to portable equipment, new energy automobiles, power grids and the like, so that the production and the life of people are changed greatly. However, with the development of socio-economic, people have higher and higher requirements for energy storage batteries, and people are pursuing industrialized batteries with high energy density and high stability, wherein the soft package full battery is generally regarded as an advantageous industrialized energy storage device. Titanium dioxide material, as an anode material for ion batteries, is considered to have the most commercial prospect due to its low production cost, stable structure, no toxicity, high safety and good cycle stability. However, the poor electronic conductivity and low ionic diffusion coefficient of titanium dioxide limit the commercial large-scale application of titanium dioxide. Therefore, in order to solve these problems, the construction of special nanostructured materials is generally adopted; the advantages of different reaction activities stably expose crystal faces; elemental doping such as boron, fluorine, nitrogen, and the like; composite carbon materials such as carbon nanotubes, graphene, and the like. The methods are proved to be capable of effectively improving the conductivity and the ion diffusion coefficient of the titanium dioxide, and finally improving the electrochemical performance of the material.

Disclosure of Invention

According to the invention, the (101) exposed crystal face titanium dioxide B phase material is successfully designed and synthesized for the first time, ammonium fluotitanate is used as a titanium source, glycolic acid is used as a reaction environment, a titanium dioxide precursor is synthesized after a simple hydrothermal reaction, and then the titanium dioxide precursor is calcined in a muffle furnace to obtain a pure phase titanium dioxide B phase material with high crystallinity, so that the structural stability of the material is improved, and the special (101) exposed crystal face structure of the obtained titanium dioxide B phase material provides more active sites for lithium, and is beneficial to ion combination and transmission. The prepared soft package full battery has high specific capacity and good cycling stability, and the capacity can still reach 46.6mAh/g after 1000 cycles when the current density is 10C (1C =335 mAh/g).

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a titanium dioxide B-phase material comprises the following steps:

(1) 1 g of ammonium fluotitanate, 0.3 g of boric acid and 3.5g of glycollic acid are sequentially added into a 50 ml polytetrafluoroethylene lining containing 35 ml of ethanol, stirred for 30min and then put into a reaction kettle device to react for 2h at 150 ℃. And washing the white precipitate obtained after naturally cooling to room temperature with deionized water, centrifuging for three times, and drying the product at 70 ℃ to finally obtain the titanium dioxide precursor.

(2) Calcining the titanium dioxide precursor in a muffle furnace at the temperature rise rate of 2 ℃/min at the temperature of 400 ℃ for 2h to obtain a final product, namely a titanium dioxide B-phase material with an exposed crystal face (101).

The titanium dioxide B phase material is applied to a soft package full battery: preparing a titanium dioxide B phase material according to the mass ratio: acetylene black: PVDF 70: 20: 10, mixing and grinding, and then uniformly coating on a copper foil to prepare a negative electrode, wherein the weight ratio of lithium ferrite: acetylene black: PVDF 80: 10: 10 as a positive electrode after mixed grinding, the electrolyte was 1.0M LiPF ₆100% DME solution, all assembly being carried out in a glove box.

The invention has the advantages that: the preparation method is simple, low in cost and good in repeatability, the fluotitanate is used as a titanium source, the appearance of an exposed surface is adjusted by boric acid, the glycolic acid is used as a reaction solvent environment to synthesize the titanium dioxide B-phase material, and the glycolic acid is beneficial to synthesizing a titanium dioxide B-phase structure; the titanium dioxide is mainly divided into four crystal forms of an anatase phase, a brookite phase, a rutile phase and a B phase, the first three crystal phases are tetragonal crystal systems and only have one ion transmission channel, and the B phase has 2 ion transmission channels because the B phase belongs to a monoclinic crystal system. According to the calculation of a density functional theory, because ion binding channels and space groups are different, the theoretical capacity of the first three crystal forms is 168 mAh/g, the B phase has the theoretical capacity of 335 mAh/g, and the B phase is more advantageous in capacity compared with the other three crystal phases.

Drawings

FIG. 1 is an XRD spectrum of a synthesized titanium dioxide B phase material, the material of the invention and TiO of a standard card₂The peak positions of the-B JCPDS NO.74-1940 are completely matched, which indicates that the material is pure phase titanium dioxide B phase material;

FIG. 2 is a scanning electron microscope image of a synthesized titanium dioxide B phase material of the present invention; as can be seen from SEM scanning electron micrographs of the materials, the materials have obvious (101) exposed crystal faces, and the materials are uniform in size and distribution and have the size of about 700 nm;

FIG. 3 is a rate performance graph of the soft package full cell under different current densities; when the current returns to 0.1C from 10C, the full battery still has the specific capacity close to the initial value, and shows good structural stability and cycling stability;

fig. 4 is a cycle performance diagram of a soft package full cell prepared according to the invention at a current density of 10C; the material still has 46.6mAh/g capacity after 1000 cycles under the current density of 10C, and shows good cycling stability of the battery.

Detailed Description

In order to make the present invention more comprehensible, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto.

Example 1

The titanium dioxide B phase material is applied to a soft package full battery: preparing a titanium dioxide B phase material according to the mass ratio: acetylene black: PVDF 70: 20: 10, mixing and grinding, and then uniformly coating on a copper foil to prepare a negative electrode, wherein the weight ratio of lithium ferrite: acetylene black: PVDF 80: 10: 10 as a positive electrode after mixed grinding, the electrolyte was 1.0M LiPF₆All assembly was performed in a glove box to give a pouch full cell.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.

Claims

1. A preparation method of a titanium dioxide B-phase material is characterized by comprising the following steps: the method comprises the following steps:

(1) sequentially adding ammonium fluotitanate, boric acid and glycollic acid into a polytetrafluoroethylene lining containing ethanol, stirring, putting into a reaction kettle device for reaction, naturally cooling to room temperature to obtain a white precipitate, and washing and drying to obtain a titanium dioxide precursor;

(2) and (2) placing the titanium dioxide precursor in the step (1) in a muffle furnace, calcining at 400 ℃ for 2h at the heating rate of 2 ℃/min, and obtaining the titanium dioxide B-phase material with the (101) exposed crystal face.

2. The method of claim 1, wherein: in the step (1), the mass ratio of the ammonium fluotitanate to the boric acid to the glycolic acid is 10: 3: 35.

3. the method of claim 1, wherein: the reaction temperature of the reaction kettle device in the step (1) is 150 ℃, and the reaction time is 2 h.

4. The method of claim 1, wherein: the temperature for drying in step (1) was 70 ℃.

5. A titanium dioxide phase B material produced by the production method according to any one of claims 1 to 4.

6. Use of the titanium dioxide B-phase material of claim 5 in a soft-pack full cell negative electrode, wherein: preparing a titanium dioxide B phase material according to the mass ratio: acetylene black: PVDF 70: 20: 10 and uniformly coating the mixture on copper foil after mixing and grinding to be used as a soft-package full-cell negative electrode.