CN107785564B

CN107785564B - VTi2.6O7.7Nanoparticles, preparation and use

Info

Publication number: CN107785564B
Application number: CN201710972587.6A
Authority: CN
Inventors: 麦立强; 彭陈; 盛进之; 安琴友
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT
Priority date: 2017-10-18
Filing date: 2017-10-18
Publication date: 2020-11-24
Anticipated expiration: 2037-10-18
Also published as: CN107785564A

Abstract

The invention relates to VTi_2.6O_7.7Nanoparticles and their preparation, consisting of small particles of 5-20 nm, wherein the small particles are VTi of anatase phase_2.6O_7.7And has good electrochemical activity. The preparation method comprises the following steps: 1) sequentially adding vanadyl acetylacetonate and titanium potassium oxalate into deionized water, and uniformly mixing to obtain a mixed solution; 2) taking out the mixed solution obtained in the step 1), and carrying out hydrothermal treatment to obtain a suspension; 3) centrifugally filtering the turbid liquid obtained in the step 2), washing the obtained precipitate, and drying to obtain VTi_2.6O_7.7And (3) nanoparticles. The invention has the beneficial effects that: the magnesium-lithium composite battery cathode material has a higher magnesium ion diffusion rate and a higher electronic conductivity, shows excellent rate performance, high-rate cycle performance and a higher specific capacity when being used as a magnesium-lithium composite battery cathode active material, and is a potential application material of a magnesium-lithium battery with high rate and long service life.

Description

VTi2.6O7.7Nanoparticles, preparation and use

Technical Field

The invention belongs to the technical field of nano materials and electrochemical devices, and particularly relates to VTi_2.6O_7.7The nanometer particle and its preparation process can be used as the positive pole active material of Mg-Li cell.

Background

In the past decade, lithium ion batteries have been widely used in the fields of electric vehicles and portable electronic devices due to their advantages of high energy density and long service life, so that our lives become more convenient. However, since the lithium resources on earth are very scarce, lithium ion batteries have been unable to meet the increasing market demand. In recent years, a magnesium-lithium hybrid battery gradually emerges, which not only has a reaction mechanism similar to that of a lithium ion battery, but also is considered to be a novel energy storage system with great potential due to the advantages of high volume energy density, no dendritic crystal growth and rich magnesium resources. In order to meet the challenges brought by the slow diffusion kinetics of magnesium ions in the cathode material, a novel cathode electrode material with the capability of fast diffusion kinetics of magnesium ions is in need of development.

TiO, an extensively studied electrode material for lithium ion batteries₂Shows a stable discharge voltage plateau (-1.7V vs. li)⁺/Li), long cycle stability and excellent rate performance. However, due to Mg²⁺In TiO₂The diffusion kinetics in (1) are slow and similar good results cannot be obtained when applied to magnesium batteries. With other positive electrode materials (VO) reported in Mg-Li hybrid batteries₂，TiS₂， FeS_x(x ═ 1 or 2)) compared with TiO₂The relatively low capacity, cycling stability and average discharge voltage still need to be further improved. The construction of substitutional solid solutions by modulating the interatomic interactions is an effective method to optimize the electrochemical performance of the cell. Vanadium, as one of the small elements with high electrochemical activity, is located right to titanium in the periodic table of elements, and is favorable for forming substitutional solid solutions due to their very similar atomic radii and electronegativity. In addition, experimental approaches to optimizing electrochemical performance of batteries by constructing substitutional solid solutions have reported modification of other materials, but in the present invention, such constructed VTi_2.6O_7.7Nanoparticles have not been reported.

Disclosure of Invention

The invention aims to provide a VTi_2.6O_7.7Nanoparticles and a preparation method thereof, the method has simple process, and the prepared VTi_2.6O_7.7The nanoparticles have excellent electrochemical properties.

The technical scheme adopted by the invention for solving the technical problems is as follows: VTi_2.6O_7.7Nanoparticles consisting of small particles of 5-20 nm, wherein the small particles are VTi of anatase phase_2.6O_7.7And has good electrochemical activity.

VTi_2.6O_7.7The preparation method of the nano-particles comprises the following steps:

1) sequentially adding vanadyl acetylacetonate and titanium potassium oxalate into deionized water, and uniformly mixing to obtain a mixed solution;

2) taking out the mixed solution obtained in the step 1), and carrying out hydrothermal treatment to obtain a suspension;

3) centrifugally filtering the turbid liquid obtained in the step 2), washing the obtained precipitate, and drying to obtain VTi_2.6O_7.7And (3) nanoparticles.

According to the scheme, the mass of the vanadyl acetylacetonate in the step 1) is 0.52-0.54g, the mass of the titanium potassium oxalate is 0.70-0.72g, and the volume of the deionized water is 75-85 mL.

According to the scheme, the volume of the mixed solution taken out in the step 2) accounts for 60-70% of the volume of the reaction container adopted in the hydrothermal treatment.

According to the scheme, the temperature of the hydrothermal treatment in the step 2) is 200 ℃, and the hydrothermal time is 9.5-10.5 h.

According to the scheme, the drying in the step 3) adopts the temperature of 60-80 ℃ under the vacuum condition.

The VTi_2.6O_7.7The application of the nano particles as the positive active material of the magnesium-lithium battery.

The invention has the beneficial effects that: the invention mainly adopts a one-step hydrothermal method to prepare the VTi with high electrochemical activity_2.6O_7.7And (3) nanoparticles. Preparation of the resulting VTi_2.6O_7.7The nano particles have higher magnesium ion diffusion rate and higher electronic conductivity, show excellent rate performance, high-rate cycle performance and higher specific capacity when being used as the cathode active material of the magnesium-lithium hybrid battery, and are potential application materials of the magnesium-lithium battery with high rate and long service life. The method has the advantages of simple process, short synthesis time and mild conditions, meets the requirement of green chemistry, and is beneficial to marketization popularization.

Drawings

FIG. 1 is a VTi of embodiment 1 of the present invention_2.6O_7.7XRD pattern of nanoparticles;

FIG. 2 is VTi of embodiment 1 of the present invention_2.6O_7.7EDS profile of nanoparticles;

FIG. 3 is VTi of embodiment 1 of the present invention_2.6O_7.7Transmission electron microscopy of nanoparticles;

FIG. 4 shows an embodiment of the present invention1 VTi_2.6O_7.7A battery cycle performance curve diagram of the magnesium-lithium battery cathode material with the nano particles at a current density of 1A/g;

FIG. 5 is VTi of embodiment 1 of the present invention_2.6O_7.7And the battery rate performance curve diagram of the magnesium-lithium battery cathode material with the nano particles under different rates.

Detailed Description

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

Example 1:

1) 0.53g of vanadyl acetylacetonate and 0.71g of potassium titanium oxalate are added successively to 80mL of deionized water and stirred until uniform mixing is achieved.

2) 70mL of the mixed solution was taken out therefrom, poured into a 100mL reaction vessel, and subjected to hydrothermal treatment at 200 ℃ for 10 hours.

3) Centrifugally filtering the suspension obtained in the step 2), washing precipitates with deionized water and alcohol for three times, and drying at 70 ℃ under a vacuum condition to obtain VTi_2.6O_7.7And (3) nanoparticles.

VTi in this example_2.6O_7.7Nanoparticles are exemplified, the structure of which is determined by X-ray diffractometry. As shown in FIG. 1, X-ray diffraction pattern (XRD) showed that the nanoparticles were VTi_2.6O_7.7The anatase phase of (A) has no other impurity phases. As shown in FIG. 2, the energy spectrum (EDS) test shows that the vanadium, titanium and oxygen elements in the sample are uniformly distributed. As shown in fig. 3, Transmission Electron Microscopy (TEM) testing indicated that the structure consisted of small particles ranging from 5 to 20 nanometers.

VTi prepared by the invention_2.6O_7.7The preparation method of the positive plate by using the nano particles as the positive active material of the magnesium-lithium battery comprises the following steps of_2.6O_7.7The nano-particles are used as an active material, the acetylene black is used as a conductive agent, the polytetrafluoroethylene is used as a binder, and the mass ratio of the active material to the acetylene black to the polytetrafluoroethylene is60:30: 10; fully mixing the raw materials in proportion, adding a small amount of isopropanol, grinding uniformly, and pressing an electrode plate with the thickness of about 0.2mm on a roll-to-roll machine; and (4) drying the pressed positive plate in an oven at 70 ℃ for 24 hours for later use. A button type magnesium-lithium hybrid battery is assembled by taking 1M LiCl dissolved in a total phenyl complex (APC) as an electrolyte, a magnesium sheet as a negative electrode and CR 2016 type stainless steel as a battery shell.

VTi obtained in this example_2.6O_7.7For example, as shown in FIG. 4, the highest discharge capacity was 260.4mAh/g at a current density of 50 mA/g; under the high current of 2A/g, the capacity of the capacitor still has 64.9 mAh/g. As shown in FIG. 4, the capacity retention rate of 84.2% still remained after 1200 cycles at a current of 1A/g, and the coulombic efficiency was almost 100%. VTi indicated by the above results_2.6O_7.7The nano particles have excellent rate capability, high-rate cycle performance and high specific capacity, and are potential application materials of long-life and high-rate magnesium-lithium hybrid batteries.

Example 2:

1) 0.53g of vanadyl acetylacetonate and 0.71g of potassium titanium oxalate were added successively to 75mL of deionized water and stirred until mixed uniformly.

2) 72mL of the mixed solution was taken out therefrom, poured into a 100mL reaction vessel, and subjected to hydrothermal treatment at 200 ℃ for 10 hours.

VTi with the product of the invention_2.6O_7.7Nanoparticles are exemplified by small particles having a diameter of 5-20 nanometers.

VTi obtained in this example_2.6O_7.7For example, the highest specific discharge capacity of the nano-particles can reach 61.2mAh/g under the current density of 2A/g.

Example 3:

VTi_2.6O_7.7preparation of nanoparticlesThe method comprises the following steps:

2) 68mL of the mixed solution was taken out therefrom, poured into a 100mL reaction vessel, and hydrothermally treated at 200 ℃ for 10.5 hours.

VTi obtained in this example_2.6O_7.7For example, the highest specific discharge capacity of the nano-particles can reach 65.2mAh/g under the current density of 2A/g.

Example 4:

1) 0.52g of vanadyl acetylacetonate and 0.70g of potassium titanium oxalate are added successively to 80mL of deionized water and stirred until uniform mixing is achieved.

VTi obtained in this example_2.6O_7.7For example, the highest specific discharge capacity of the nano-particles can reach 64.7mAh/g under the current density of 2A/g.

Example 5:

1) 0.54g of vanadyl acetylacetonate and 0.71g of potassium titanium oxalate are added successively to 80mL of deionized water and stirred until uniform mixing is achieved.

2) 69mL of the mixed solution was taken out, poured into a 100mL reaction vessel, and subjected to hydrothermal treatment at 200 ℃ for 10 hours.

3) Centrifugally filtering the suspension obtained in the step 2), washing precipitates with deionized water and alcohol for three times, and drying at 65 ℃ under a vacuum condition to obtain VTi_2.6O_7.7And (3) nanoparticles.

VTi obtained in this example_2.6O_7.7For example, the highest specific discharge capacity of the nano-particles can reach 61.3mAh/g under the current density of 2A/g.

Example 6:

2) 71mL of the mixed solution was taken out, poured into a 100mL reaction vessel, and hydrothermally treated at 200 ℃ for 9.5 hours.

3) Centrifugally filtering the suspension obtained in the step 2), washing precipitates with deionized water and alcohol for three times, and drying at 75 ℃ under a vacuum condition to obtain VTi_2.6O_7.7And (3) nanoparticles.

Claims

1.VTi_2.6O_7.7Nanoparticles consisting of small particles of 5-20 nm, wherein the small particles are VTi of anatase phase_2.6O_7.7Has good electrochemical activity as followsThe product obtained by the preparation method comprises the following steps:

1) sequentially adding vanadyl acetylacetonate and titanium potassium oxalate into deionized water, and uniformly mixing to obtain a mixed solution; the mass of the vanadyl acetylacetonate is 0.52-0.54g, the mass of the titanium potassium oxalate is 0.70-0.72g, and the volume of the deionized water is 75-85 mL;

2) taking out the mixed solution obtained in the step 1), and carrying out hydrothermal treatment to obtain a suspension; the volume of the taken-out mixed solution accounts for 65-75% of the volume of the reaction container adopted by the hydrothermal treatment; the temperature of the hydrothermal treatment is 200 ℃, and the hydrothermal time is 9.5-10.5 h;

3) centrifugally filtering the turbid liquid obtained in the step 2), washing the obtained precipitate, and drying to obtain VTi_2.6O_7.7And (3) drying the nano particles at the temperature of 60-80 ℃ under a vacuum condition.

2. The VTi of claim 1_2.6O_7.7The application of the nano particles as the positive active material of the magnesium-lithium battery.