CN108134075B

CN108134075B - Sodium titanate microsphere and application thereof in sodium ion battery

Info

Publication number: CN108134075B
Application number: CN201711287104.5A
Authority: CN
Inventors: 高林; 陈思; 杨学林
Original assignee: China Three Gorges University CTGU
Current assignee: China Three Gorges University CTGU
Priority date: 2017-12-07
Filing date: 2017-12-07
Publication date: 2020-04-24
Anticipated expiration: 2037-12-07
Also published as: CN108134075A

Abstract

The invention provides a sodium titanate microsphere with high tap density and application thereof in a sodium ion battery. Specifically, a certain amount of tetrabutyl titanate is dissolved in an acetic acid solution to form milky turbid liquid, and the milky turbid liquid is annealed in the air after hydrothermal treatment to obtain TiO₂And (4) slicing and balling. In order to obtain high tap density of Na₂Ti₃O₇Microspheres, we will turn the above TiO into₂Placing the microspheres in a high-concentration NaOH solution for hydrothermal reaction, and annealing at 500 ℃ to obtain Na with high tap density₂Ti₃O₇Microspheres having a tap density of up to 1 g cm as measured by a tap density tester^‑3. With this high tap density of Na₂Ti₃O₇The microsphere has excellent electrochemical performance as the cathode material of the sodium ion battery and still has 85 mAh g under 3C multiplying power^‑1The capacity retention rate of the specific capacity is 84.1 percent after 20 cycles.

Description

Sodium titanate microsphere and application thereof in sodium ion battery

Technical Field

The invention relates to a sodium ion battery material with high tap density, in particular to Na₂Ti₃O₇A preparation method of microspheres belongs to the field of sodium ion batteries.

Technical Field

Since the 21 st century, with the improvement of the productivity level and the rapid development of the industrial level, a great deal of non-renewable fossil energy is used, so that the problems of air pollution, greenhouse gas emission and the like are increasingly prominent, and the daily life of people is greatly influenced. Therefore, the search for clean and environment-friendly alternative energy sources is urgently needed to be promoted. As far as the scientific technology is mastered at present, the new clean energy sources which can be utilized are wind energy, solar energy, tidal energy and the like, and the development of high-performance energy storage equipment is full of challenges. At present, lead-acid batteries, nickel-metal hydride batteries and lithium ion batteries are precedent for energy storage systems, such as energy storage devices matched with wind power stations, power exchange devices of communication base stations and the like. Among these battery systems, lithium ion batteries are superior in their excellent charge and discharge capacity and stable cycle performance, and are widely used in clean energy storage, electric vehicles, and portable electronic devices. With the rapid development of digital products and the automobile industry, the shortage of lithium resources is gradually a fatal factor for limiting the development of lithium ion batteries, so that the search for a substitute of the lithium ion battery is a current research hotspot. Sodium and lithium are in the same main group and have similar physical and chemical properties, and compared with the lithium resource, the sodium resource has richer reserves, wide distribution and simple extraction. Meanwhile, the sodium ion battery has a working principle similar to that of the lithium ion battery. Based on the above advantages, the sodium ion battery is likely to become the next generation energy storage device.

However, sodium ion batteries face significant challenges in practical applications, including low energy efficiency and unstable cycling performance. One of the main factors causing the above problems is the lack of an effective anode material. At present, titanium-based sodium ion battery cathode materials are widely concerned due to the characteristics of effective Na storage activity, high stability, low cost and no toxicity. In the research of many sodium-ion battery cathode material systems, Na₂Ti₃O₇Has larger theoretical capacity (310 mAh g)^-1) The material is an ideal cathode material of the sodium-ion battery. The invention discloses a sodium titanate microsphere with high tap density, which is used as a negative electrode material of a sodium-ion battery and shows excellent electrochemical performance.

Disclosure of Invention

The invention relates to a preparation method of a sodium ion battery cathode material, wherein the cathode material is Na₂Ti₃O₇The shape of the material is spherical. This Na salt₂Ti₃O₇The diameter of the microsphere is 2-4 mu m, and the pore size distribution is concentrated in 5 nm. The preparation method comprises the following steps: weighing a proper amount of glacial acetic acid into a hydrothermal lining, adding a certain amount of tetrabutyl titanate, stirring for 5 minutes to obtain a milky white solution, then carrying out hydrothermal treatment for 5-12 hours in a blast oven at 120-200 ℃, adding deionized water into the hydrothermally cooled intermediate phase white gel, centrifuging for 3-6 times until the gel is neutral, then placing the gel in a blast oven at 50 ℃ and drying for 24-36 hours until the gel is completely dried to obtain layered multi-stage TiO₂And (3) microspheres. Weighing a proper amount of sodium hydroxide in a beaker, and adding the layered multi-stage TiO obtained after drying₂Adding a proper amount of deionized water into the microspheres, fully stirring for 10 min until the microspheres are completely dissolved, transferring the dissolved solution into a hydrothermal liner, adding the deionized water to 80% of the volume of the liner, and then carrying out hydrothermal treatment for 8-15 h in a forced air oven at 180-250 ℃. Cooling the waterAnd adding deionized water into the cooled liquid for suction filtration, and then placing the obtained product in a blast oven at 80 ℃ for drying for 24-36 h until the product is completely dried into powder. Finally, the powder is placed in an air atmosphere for annealing treatment at 500 ℃ for 1-3 h, and Na is obtained after cooling₂Ti₃O₇And (3) a negative electrode material.

The volume ratio of the glacial acetic acid to the tetrabutyl titanate is 50: 1-5, and the concentration of the sodium hydroxide is 1-5M;

said Na₂Ti₃O₇The appearance is spherical, the surface is similar to a sunflower shape, Na₂Ti₃O₇The diameter of the microsphere is 2-4 mu m, and the tap density is up to 1 g cm^-3The specific surface area is 6.87 m²g^-1。

Na according to the invention₂Ti₃O₇The preparation method, the material and the performance of the cathode material have the following characteristics:

(1) the synthesis process is simple, easy to operate, good in repeatability and low in cost;

(2) prepared Na₂Ti₃O₇The negative electrode material is spherical, and the Na₂Ti₃O₇The diameter of the microsphere is 2-4 mu m, the pore size distribution is concentrated at 5 nm, and the specific surface area is 6.87 m²g^-1；

(3) Na produced by the invention₂Ti₃O₇The material used as the cathode material of the sodium-ion battery shows better cycle performance, and the tap density of the material is as high as 1 g cm^-3And has the advantage of high volume energy density.

Drawings

Figure 1 XRD pattern of the sample prepared in example 1.

FIG. 2 SEM image of sample prepared in example 1.

FIG. 3 the nitrogen de-adsorption curve and the corresponding pore size distribution curve for the samples prepared in example 1.

Fig. 4 cycle performance graph (a) and charge and discharge graph (b) at 3C rate of the sample prepared in example 1.

FIG. 5 SEM image of sample prepared in example 2.

FIG. 6 SEM image of sample prepared in example 3.

FIG. 7 SEM image of sample prepared in example 4.

Detailed Description

Example 1

Measuring 50mL of glacial acetic acid in a hydrothermal lining by using a measuring cylinder, adding 1000 muL of tetrabutyl titanate in the stirring process to obtain a milky white solution, then carrying out hydrothermal treatment for 8 h in a 150 ℃ blast oven to obtain mesophase white gel, adding deionized water, centrifuging for 5 times until the mesophase white gel is neutral, then placing the mesophase white gel in a 50 ℃ blast oven to dry for 24h until the mesophase white gel is completely dried to obtain layered multi-stage TiO₂And (3) microspheres. 6.4g of sodium hydroxide is weighed into a beaker, and the layered multi-stage TiO obtained after drying is added₂Adding 20 mL of deionized water into the microspheres, fully stirring for 10 min until the microspheres are completely dissolved, transferring the dissolved solution into a hydrothermal liner, adding the deionized water to 80% of the volume of the liner, and then carrying out hydrothermal treatment for 12h in a blast oven at 200 ℃. And adding deionized water into the liquid after the hydrothermal cooling, performing suction filtration, and then putting the obtained product into a blast oven at 80 ℃ for 24 hours until the product is completely dried into powder. Finally, the powder is placed in the air atmosphere for annealing treatment for 1 h at 400 ℃, and Na is obtained after cooling₂Ti₃O₇And (3) a negative electrode material. The prepared sample is analyzed by XRD pattern, as shown in figure 1, all diffraction peaks and Na₂Ti₃O₇(XRD card JCPDS, No. 31-1329) shows that we have successfully prepared Na₂Ti₃O₇And (3) sampling. SEM characterization of the samples, as can be seen in FIG. 2, Na₂Ti₃O₇The material is spherical, and the diameter of the microsphere is 2-4 mu m. The results of the nitrogen desorption test are shown in FIG. 3, and the precursor TiO₂Has a specific surface area of 116.6 m²g^-1The pore size distribution was centered at 5 nm and 20 nm. Na obtained after treatment with NaOH solution₂Ti₃O₇The specific surface area of the microspheres is 6.87 m²g^-1The pore size distribution is mainly centered at 5 nm. Na obtained in the above step₂Ti₃O₇Material (8: 1:1, Na)₂Ti₃O₇: acetylene black: PVDF) was coated on a copper foil, cut into 14 mm round pieces, and vacuum dried at 120 ℃ for 12 hours. A metal sodium sheet is taken as a counter electrode, Grade GF/D is taken as a diaphragm, and NaPF is dissolved₆(1 mol L^-1) The solution of EC + DEC (volume ratio of 1: 1) of (A) was used as an electrolyte and assembled into a CR2025 type cell in an argon-protected glove box. And standing for 8 hours after the battery is assembled, and then performing constant-current charging and discharging tests by using a CT2001A battery test system, wherein the test voltage is 0.01-2.5V. FIG. 4 shows Na prepared in example 1₂Ti₃O₇The electrode still has 85 mAh g under 3C multiplying power^-1The capacity retention rate of the specific capacity is 84.1 percent after 20 cycles, and the electrochemical performance is better.

Example 2

Measuring 50mL of glacial acetic acid in a hydrothermal lining by using a measuring cylinder, adding 1000 muL of tetrabutyl titanate in the stirring process to obtain a milky white solution, then carrying out hydrothermal treatment in a 150 ℃ blast oven for 8 hours to obtain a mesophase white gel, adding deionized water, centrifuging for 5 times until the gel is neutral, then placing the gel in a 50 ℃ blast oven for drying for 24 hours until the gel is completely dried to obtain layered multi-stage TiO₂And (3) microspheres. 3.2 g of sodium hydroxide is weighed into a beaker, and the layered multi-stage TiO obtained after drying is added₂Adding 20 mL of deionized water into the microspheres, fully stirring for 10 min until the microspheres are completely dissolved, transferring the dissolved solution into a hydrothermal liner, adding the deionized water to 80% of the volume of the liner, and then carrying out hydrothermal treatment in a blast oven at 200 ℃ for 12 h. And adding deionized water into the liquid after the hydrothermal cooling, performing suction filtration, and then putting the obtained product into a blast oven at 80 ℃ for 24 hours until the product is completely dried into powder. Finally, the powder is placed in the air atmosphere for annealing treatment for 1 h at 500 ℃, and Na is obtained after cooling₂Ti₃O₇And (3) a negative electrode material. As can be seen from FIG. 5, Na produced in example 2₂Ti₃O₇Is a microsphere with the diameter of 2-4 mu m.

Example 3

Measuring 50mL of glacial acetic acid in a hydrothermal lining by using a measuring cylinder, adding 1000 muL of tetrabutyl titanate in the stirring process to obtain a milky white solution, and then carrying out water treatment in a 150 ℃ blast ovenHeating for 8 h, adding deionized water into the intermediate phase white gel obtained by hydrothermal treatment, centrifuging for 5 times until the intermediate phase white gel is neutral, and then placing the intermediate phase white gel in a blowing oven at 50 ℃ for drying for 24h until the intermediate phase white gel is completely dried to obtain layered multilevel TiO₂And (3) microspheres. 6.4g of sodium hydroxide is weighed into a beaker, and the layered multi-stage TiO obtained after drying is added₂Adding 20 mL of deionized water into the microspheres, fully stirring for 10 min until the microspheres are completely dissolved, transferring the dissolved solution into a hydrothermal liner, adding the deionized water to 80% of the volume of the liner, and then carrying out hydrothermal treatment for 12h in a blast oven at 200 ℃. And adding deionized water into the liquid after the hydrothermal cooling, performing suction filtration, and then putting the obtained product into a blast oven at 80 ℃ for 24 hours until the product is completely dried into powder. Finally, the powder is placed in the air atmosphere for annealing treatment for 1 h at 500 ℃, and Na is obtained after cooling₂Ti₃O₇And (3) a negative electrode material. As can be seen from FIG. 6, Na produced in example 3₂Ti₃O₇Is a microsphere with the diameter of 2-4 mu m.

Example 4

Measuring 50mL of glacial acetic acid in a hydrothermal lining by using a measuring cylinder, adding 1000 muL of tetrabutyl titanate in the stirring process to obtain a milky white solution, then carrying out hydrothermal treatment in a 150 ℃ blast oven for 8 hours to obtain a mesophase white gel, adding deionized water, centrifuging for 5 times until the gel is neutral, then placing the gel in a 50 ℃ blast oven for drying for 24 hours until the gel is completely dried to obtain layered multi-stage TiO₂And (3) microspheres. Weighing 16g of sodium hydroxide in a beaker, and adding the layered multi-stage TiO obtained after drying₂Adding 20 mL of deionized water into the microspheres, fully stirring for 10 min until the microspheres are completely dissolved, transferring the dissolved solution into a hydrothermal liner, adding the deionized water to 80% of the volume of the liner, and then carrying out hydrothermal treatment in a blast oven at 200 ℃ for 12 h. And adding deionized water into the liquid after the hydrothermal cooling, performing suction filtration, and then putting the obtained product into a blast oven at 80 ℃ for 24h until the product is completely dried into powder. Finally, the powder is placed in the air atmosphere for annealing treatment for 1 h at 500 ℃, and Na is obtained after cooling₂Ti₃O₇And (3) a negative electrode material. As can be seen from FIG. 7, Na produced in example 4₂Ti₃O₇Is a microsphere with the diameter of 2-4 mu m.

Claims

1. The preparation method of the sodium titanate microspheres is characterized in that the chemical structural formula of the microspheres is Na₂Ti₃O₇Said Na₂Ti₃O₇The diameter of the microsphere is 2-4 μm, the pore size distribution is concentrated at 5 nm, and the tap density is 0.5-1 g cm^-3The specific surface area is 6.5-8 m²g^-1The method comprises the following steps:

(1) adding glacial acetic acid into the hydrothermal lining, adding tetrabutyl titanate, stirring to obtain a milky white solution, performing hydrothermal reaction in a forced air oven for 5-12 h, and cooling to obtain an intermediate phase white gel;

(2) adding deionized water into the intermediate phase white gel obtained in the step (1), centrifuging until the gel is neutral, and drying to obtain layered multi-stage TiO₂Microspheres;

(3) weighing sodium hydroxide, and layering the multilevel TiO in the step (2)₂Adding deionized water into microspheres, stirring until the microspheres are completely dissolved, transferring the dissolved solution into a hydrothermal liner, adding the deionized water to 70-80% of the volume of the liner, carrying out hydrothermal reaction in a forced air oven for 8-15 h, and cooling to obtain a mesophase liquid;

(4) adding deionized water into the intermediate phase liquid subjected to hydrothermal cooling in the step (3), performing suction filtration, drying, annealing at 400-500 ℃ for 1-3 h in an air atmosphere, and cooling to obtain Na₂Ti₃O₇And (3) a negative electrode material.

2. The method for preparing sodium titanate microspheres according to claim 1, wherein the volume ratio of glacial acetic acid to tetrabutyl titanate is 50: 1-5, wherein the concentration of the sodium hydroxide is 1-5M.

3. The method for preparing sodium titanate microspheres according to claim 1, wherein the hydrothermal reaction temperature in step (1) is 120-200 ℃.