CN109888245B

CN109888245B - Titanium niobium oxygen/carbon composite material with oxygen vacancy and carbon coating adjustment and preparation method and application thereof

Info

Publication number: CN109888245B
Application number: CN201910221605.6A
Authority: CN
Inventors: 夏新辉; 邓盛珏; 周荣帆; 涂江平; ***
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2019-03-21
Filing date: 2019-03-21
Publication date: 2021-01-15
Anticipated expiration: 2039-03-21
Also published as: CN109888245A

Abstract

The invention discloses a titanium niobium oxygen (Ti) with oxygen vacancy and carbon coating regulation₂Nb₁₀O_29‑x) A/carbon composite material, a preparation method and application thereof, and Ti prepared by a hydrothermal method and a high-temperature sintering method₂Nb₁₀O₂₉Finally obtaining Ti by high-temperature sintering in acetylene₂Nb₁₀O_29‑x@ C target product with large specific surface area, Ti₂Nb₁₀O_29‑xThe @ C nano-particles can increase the contact area of electrolyte and an electrode, provide a larger and more effective active reaction area, and simultaneously accelerate the electron conduction rate and improve the electrochemical performance. Ti of the invention₂Nb₁₀O_29‑xThe @ C material has the characteristics of long cycle life, high energy and power density, is particularly suitable for serving as a lithium ion battery cathode material, and has wide application prospects in the fields of mobile communication, electric automobiles, solar power generation, aerospace and the like.

Description

Titanium niobium oxygen/carbon composite material with oxygen vacancy and carbon coating adjustment and preparation method and application thereof

Technical Field

The invention relates to the field of lithium ion battery cathode materials, in particular to a titanium niobium oxygen/carbon composite material with oxygen vacancy and carbon coating regulation, and a preparation method and application thereof.

Background

The rapid expansion of the consumer market for electronic products has greatly increased the demand for high performance, highly stable battery materials. The lithium-storage material of titanium niobate has a good lithium-storage structure, thereby determining that the material has good electrochemical performance. The negative electrode materials mainly used at present comprise graphite, lithium titanate and the like, but have serious problems, graphite is easy to form an SEI (Solid Electrolyte interface) film due to a low voltage platform of the graphite to cause lithium dendrites and possibly cause explosion, and lithium titanate cannot generate the SEI film due to a high voltage platform of the lithium titanate, but has low theoretical capacity (175mAh g)^-1) So that the energy storage performance is not ideal. Compared with these common anode materials, the titanium niobate compound has larger theoretical capacity and relative safety stability. However, the titanium niobate compound also has some disadvantages, such as low electronic conductivity, small lithium ion diffusion coefficient, and the like.

Disclosure of Invention

The invention aims to provide a titanium niobium oxygen (Ti) with oxygen vacancy and carbon coating regulation aiming at the graphite with low safety performance and the lithium titanate lithium ion battery cathode material with low theoretical capacity₂Nb₁₀O_29-x) A/carbon composite material, a preparation method and application thereof, and the Ti₂Nb₁₀O_29-xThe @ C electrode material has high power density, high energy density and high safety and stability.

Titanium niobium oxygen (Ti) with oxygen vacancy and carbon coating adjustment₂Nb₁₀O_29-x) The preparation method of the/carbon composite material comprises the following steps:

1) dissolving niobium pentachloride and isopropyl titanate in an absolute ethyl alcohol solution, stirring and mixing uniformly to form a mixed solution, adding the mixed solution into a polytetrafluoroethylene high-pressure kettle, sealing and heating, wherein the hydrothermal temperature is 140-220 ℃, the hydrothermal time is 4-28 hours, cooling, taking out a sample, washing and drying to obtain an intermediate product, sintering the intermediate product in a tube furnace at the temperature of 600-900 ℃ for 0.5-4 hours to obtain a target precursor (Ti)₂Nb₁₀O₂₉)；

2) The target precursor (Ti) obtained in the step 1) is added₂Nb₁₀O₂₉) Placing the titanium-niobium-oxygen/carbon composite material into a tube furnace, introducing acetylene gas into the tube furnace at the temperature of 200 ℃ and 900 ℃ and sintering the titanium-niobium-oxygen/carbon composite material for 1 to 5 hours to obtain the titanium-niobium-oxygen/carbon composite material (namely Ti) with oxygen vacancy and carbon coating regulation₂Nb₁₀O_29-x@ C material).

In the present invention, Ti is added₂Nb₁₀O₂₉Introducing acetylene gas for sintering to obtain Ti₂Nb₁₀O_29-xThe material @ C, where x represents an oxygen vacancy (i.e., a deficient oxygen atom) and is formed by reduction of an oxygen atom by acetylene, is randomly generated with no specific value. Ti₂Nb₁₀O_29-xThe @ C material can effectively improve the electron conduction rate, thereby improving the electrochemical performance of the material. Ti₂Nb₁₀O_29-xThe @ C can be used as a lithium ion battery cathode material with high energy density, high power density and high safety and stability.

In the step 1), the molar ratio of niobium pentachloride to isopropyl titanate is 3-7: 1, more preferably 4 to 6: 1, most preferably 5: 1.

the hydrothermal temperature is 160-200 ℃, the hydrothermal time is 10-24 hours,

sintering the target precursor in a tube furnace at the temperature of 750-850 ℃ for 1-2 hours,

in the step 2), the target precursor (Ti) obtained in the step 1) is added₂Nb₁₀O₂₉) Placing the mixture into a tube furnace and introducing acetylene gas into the tube furnace at the temperature of 300 ℃ and 600 ℃ for sintering for 1.5 to 2.5 hours.

Prepared oxygen vacancy and carbon coating regulated titanium niobium oxygen/carbon composite material (namely Ti)₂Nb₁₀O_29-x@ C material) having a large specific surface area, Ti₂Nb₁₀O_29-xThe @ C nano-particles can increase the contact area of electrolyte and a motor, provide a larger and more effective active reaction area, and accelerate the electron conduction rate by coating carbon, and the carbon coating technology also generates oxygen vacancies, wherein x in the molecular formula represents the oxygen vacancies, so that the mechanical stress is improved, and the electrochemical performance is improved.

The titanium niobium oxygen/carbon composite material with the oxygen vacancy and carbon coating regulation is particularly suitable for being used as a negative electrode material of a lithium ion battery. What is needed isThe above Ti₂Nb₁₀O₂₉@ C material possesses high theoretical capacity (396mAh g^-1) At 5C (1C 396mAh g)^-1) The discharge specific capacitance under the current density can reach 310mAh g^-1And the discharge specific capacitance retention rate after 500 cycles reaches more than 90 percent, has better electronic conductivity and higher safety stability, and Ti₂Nb₁₀O₂₉The @ C nanoparticles have an average diameter of about 50 nm. The Ti₂Nb₁₀O₂₉The @ C material is used as a novel titanium niobium oxygen/carbon composite material.

Compared with the prior art, the invention has the following advantages:

the method of the invention prepares Ti by simple hydrothermal method and high-temperature sintering₂Nb₁₀O₂₉Finally, obtaining Ti by introducing acetylene and sintering at high temperature₂Nb₁₀O_29-x@ C target product. The preparation method is simple and convenient, and is easy to control.

Ti prepared by the invention₂Nb₁₀O_29-xA material of @ C electrode having a large specific surface area, Ti₂Nb₁₀O_29-xThe @ C nano-particles can increase the contact area of electrolyte and a motor, provide a larger and more effective active reaction area, and wrap carbon to accelerate the electron conduction rate, so that the carbon wrapping technology also generates oxygen vacancies, improves the mechanical stress and improves the electrochemical performance. The invention overcomes the defects of SEI film formation and reaction kinetics, thereby realizing high power discharge performance and simultaneously keeping high energy density, and forming the novel lithium ion battery cathode material with high power, high energy density and high safety and stability.

Drawings

FIG. 1 shows Ti obtained in example 1₂Nb₁₀O_29-xThe XRD pattern of @ C;

FIG. 2 shows Ti obtained in example 1₂Nb₁₀O_29-xScanning electron micrographs of @ C;

FIG. 3 shows Ti obtained in example 1₂Nb₁₀O_29-xTransmission electron micrograph of @ C.

Detailed Description

The present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

Example 1

Weighing 0.2849g C₁₂H₂₈O₄Ti, 60mL of absolute ethanol, stirring for 10 minutes, and then adding 1.35g of NbCl₅The molar ratio of niobium pentachloride to isopropyl titanate is 5:1, stirring for 15 minutes until complete dissolution. After being mixed evenly, the solution is transferred into a polytetrafluoroethylene high-pressure reaction kettle, the high-pressure reaction kettle is sealed, and the hydrothermal reaction is carried out for 24 hours at the temperature of 200 ℃. And cooling to room temperature of 25 ℃ after reaction, pouring the solution, taking out a sample, washing with deionized water, drying, and naturally cooling to room temperature of 25 ℃ to obtain an intermediate product. Finally, the intermediate product is put into a tube furnace to be sintered for 2 hours at 800 ℃ to obtain a target precursor (Ti)₂Nb₁₀O₂₉) And introducing acetylene to sinter at 300 deg.C for 2 hr to obtain Ti₂Nb₁₀O_29-x@ C target product (i.e., oxygen vacancy and carbon-clad modulated titanium niobium oxygen/carbon composite).

FIG. 1 shows Ti obtained in example 1₂Nb₁₀O_29-xXRD pattern of @ C, TNO in FIG. 1 representing Ti₂Nb₁₀O₂₉，TNO_-x@C₃Is represented by Ti₂Nb₁₀O_29-x@ C target product; FIG. 2 shows Ti obtained in example 1₂Nb₁₀O_29-xScanning electron micrographs of @ C; FIG. 3 shows Ti obtained in example 1₂Nb₁₀O_29-xTransmission electron micrograph of @ C. Ti₂Nb₁₀O₂₉The @ C nanoparticles have an average diameter of about 50 nm.

Example 2

Weighing 0.2849g C₁₂H₂₈O₄Ti, 60mL of absolute ethanol, stirring for 10 minutes, and then adding 1.35g of NbCl₅The molar ratio of niobium pentachloride to isopropyl titanate is 5:1, stirring for 15 minutes until complete dissolution. After being mixed evenly, the solution is transferred into a polytetrafluoroethylene high-pressure reaction kettle, the high-pressure reaction kettle is sealed, and the hydrothermal reaction is carried out for 10 hours at the temperature of 160 ℃. After the reaction, the reaction mixture was cooled to room temperature of 25 ℃ and the solution was poured offAnd (4) taking out a sample, washing and drying the sample by using deionized water, and naturally cooling the sample to room temperature of 25 ℃ to obtain an intermediate product. Finally, the intermediate product is put into a tube furnace to be sintered for 2 hours at 750 ℃ to obtain a target precursor (Ti)₂Nb₁₀O₂₉) And introducing acetylene gas to sinter at 500 deg.C for 2 hr to obtain Ti₂Nb₁₀O_29-x@ C target product (i.e., oxygen vacancy and carbon-clad modulated titanium niobium oxygen/carbon composite).

Example 3

Weighing 0.2849g C₁₂H₂₈O₄Ti, 60mL of absolute ethanol, stirring for 10 minutes, and then adding 1.35g of NbCl₅The molar ratio of niobium pentachloride to isopropyl titanate is 5:1, stirring for 15 minutes until complete dissolution. After being mixed evenly, the solution is transferred into a polytetrafluoroethylene high-pressure reaction kettle, the high-pressure reaction kettle is sealed, and the hydrothermal reaction is carried out for 15 hours at the temperature of 180 ℃. And cooling to room temperature of 25 ℃ after reaction, pouring the solution, taking out a sample, washing with deionized water, drying, and naturally cooling to room temperature of 25 ℃ to obtain an intermediate product. Finally, the intermediate product is put into a tube furnace to be sintered for 1 hour at 850 ℃ to obtain a target precursor (Ti)₂Nb₁₀O₂₉) And introducing acetylene gas to sinter at 600 deg.C for 2 hr to obtain Ti₂Nb₁₀O_29-x@ C target product (i.e., oxygen vacancy and carbon-clad modulated titanium niobium oxygen/carbon composite).

Performance testing

Ti prepared in the above examples 1 to 3₂Nb₁₀O_29-xThe material @ C is respectively used as a positive electrode (the negative electrode active material prepared in the experiment, a binder polyvinylidene fluoride (PVDF1300) and a conductive agent acetylene black are uniformly mixed according to the mass ratio of 75:15:10, diluted to a proper viscosity by N-methylpyrrolidone (NMP) and coated on a battery-grade copper foil, and then the battery-grade copper foil is placed in a vacuum drying oven to be dried for 12 hours at 120 ℃ in a vacuum mode). The metal lithium sheet is used as a negative electrode, and LiPF is selected as electrolyte₆Dissolving it in a mixture of ethylene carbonate (DC) and dimethyl carbonate (DMC) and Ethylene Carbonate (EC) in a mass ratio of 1:1:1, LiPF₆At a concentration of 1mol L^-1. And assembling the button cell in the glove box. Testing batteries separately in a blue testerAnd (4) performance. The charging and discharging voltage is 1.0-2.5V, and the Ti is measured in a circulation mode in an environment of 25 +/-1 DEG C₂Nb₁₀O_29-xThe material @ C has reversible charge-discharge specific capacity, charge-discharge cycle performance and high rate characteristic.

The performance test results are as follows:

ti of example 1, example 2 and example 3₂Nb₁₀O_29-x@ C material at 5C (1C ═ 396mAh g^-1) The discharge specific capacitance under the current density is 310mAh g respectively^-1、295mAh g^-1And 299mAh g^-1And the discharge specific capacitance retention rate after 500 cycles reaches more than 90%. As can be seen, Ti obtained as described above₂Nb₁₀O_29-xThe @ C material has high charge and discharge capacity and good cycle stability.

This is Ti prepared by the present invention₂Nb₁₀O_29-xA material of @ C electrode having a large specific surface area, Ti₂Nb₁₀O_29-xThe @ C nanoparticles can increase the contact area of the electrolyte and the electrode. The carbon coating accelerates the electron conduction rate, and the carbon coating technology also generates oxygen vacancies, improves the mechanical stress and improves the electrochemical performance. Thus, the Ti of the present invention₂Nb₁₀O_29-xThe @ C material has the characteristics of long cycle life, high energy and power density, and has wide application prospects in the fields of mobile communication, electric automobiles, solar power generation, aerospace and the like.

Claims

1. A preparation method of a titanium niobium oxygen/carbon composite material with adjusted oxygen vacancy and carbon coating is characterized by comprising the following steps:

1) dissolving niobium pentachloride and isopropyl titanate in an absolute ethanol solution, stirring and mixing uniformly to form a mixed solution, adding the mixed solution into a polytetrafluoroethylene high-pressure kettle, sealing and heating, wherein the hydrothermal temperature is 140-220 ℃, the hydrothermal time is 4-28 hours, cooling, taking out a sample, washing and drying to obtain an intermediate product, and sintering the intermediate product in a tube furnace at the temperature of 600-900 ℃ for 0.5-4 hours to obtain a target precursor;

2) putting the target precursor obtained in the step 1) into a tube furnace, and introducing acetylene gas into the tube furnace at the temperature of 300 ℃ and 600 ℃ for sintering for 1.5-2.5 hours to obtain the titanium niobium oxygen/carbon composite material with oxygen vacancy and carbon coating regulation.

2. The preparation method of claim 1, wherein in the step 1), the molar ratio of the niobium pentachloride to the isopropyl titanate is 3-7: 1.

3. the preparation method according to claim 2, wherein in the step 1), the molar ratio of the niobium pentachloride to the isopropyl titanate is 4-6: 1.

4. the preparation method according to claim 3, wherein in the step 1), the molar ratio of the niobium pentachloride to the isopropyl titanate is 5: 1.

5. the preparation method according to claim 1, wherein the hydrothermal temperature in step 1) is 160 ℃ to 200 ℃ and the hydrothermal time is 10 to 24 hours.

6. The method as claimed in claim 1, wherein in step 1), the intermediate product is sintered in a tube furnace at 750-850 ℃ for 1-2 hours.

7. The oxygen vacancy and carbon cladding adjusted titanium niobium oxygen/carbon composite material prepared by the preparation method of any one of claims 1 to 6.

8. The use of the oxygen-vacancy and carbon-clad modulated titanium niobium oxygen/carbon composite of claim 7 as a negative electrode material for a lithium ion battery.