CN105948108B - A kind of sodium lithium titanate nano wire and preparation method thereof - Google Patents

Abstract

The invention discloses a preparation method of lithium sodium titanate nanowires. In the invention, a certain amount of lithium salt, sodium salt and titanium salt are dissolved in a mixed solution of dimethylformamide and ethanol, and glacial acetic acid and high Molecules make it form a clear solution, the clear solution is electrospun at a certain voltage and a certain volume flow rate, the electrospinning product is dried at a constant temperature, and then sintered at a high temperature to obtain the corresponding NaLiTiO ₃ lithium sodium titanate nanowires, and their electrochemical performance and lithium storage performance were studied. The invention successfully realizes the preparation of NaLiTiO ₃ lithium sodium titanate nanowires, which are negative electrode materials of lithium ion batteries, and the nanowires have excellent physical and chemical properties. Electrochemical experiments prove that the NaLiTiO ₃ lithium sodium titanate nanowires prepared by this method have broad application prospects as lithium-ion battery negative electrode materials. In the whole preparation process, the operation is simple, the cost of raw materials is low, the investment in equipment is small, and it is suitable for mass production.

Description

A lithium sodium titanate nanowire and preparation method thereof

technical field

The invention belongs to the field of lithium ion battery materials, and in particular relates to a preparation method of NaLiTiO ₃ lithium sodium titanate nanofibers, which are negative electrode materials of lithium ion batteries.

Background technique

As a potential lithium-ion battery material, lithium-sodium titanate compound has the advantages of good ionic conductivity, high theoretical capacity, and no solid electrolyte interface (SEI) film will be formed during charge and discharge. Materials assembled into batteries can obtain lithium-ion batteries with high output voltage, safety, and long cycle life, and are expected to meet the power requirements of electric vehicles. However, the large rate performance of lithium sodium titanate negative electrode material is poor.

There are many ways to solve the high-rate performance of lithium sodium titanate negative electrode materials, and the most effective way is to nanometerize the material. The large specific surface area of zero-dimensional nanomaterials increases the electrochemically active surface energy, which will lead to poor cycle performance of materials. Compared with zero-dimensional, two-dimensional and three-dimensional nanomaterials, one-dimensional nanomaterials have superior physical and electrical properties. properties, which provide a good system for the study of dimensionality and size effects on electron transport, heat conduction, and mechanical properties. One-dimensional nanomaterials are of great value in the field of basic research, and have broad application prospects in integrated circuit nano-components. Researchers can easily integrate them into nano-functional electronic devices.

At present, the reported preparation methods of lithium sodium titanate mainly include: high-temperature solid-phase synthesis method and sol-gel method. The high-temperature solid-phase method has shortcomings such as long sintering time, high temperature, and high energy consumption, and the synthesized materials are relatively uneven, low in purity, relatively large in particle size, and relatively poor in electrochemical performance; while the sol-gel method The preparation process is relatively complicated, and the temperature of the reaction and the speed of solution dropwise need to be controlled, and a long aging time is required, which increases the cost. In order to solve the shortcomings of the above two methods and improve the high-rate performance of the lithium sodium titanate material, the present invention uses an electrospinning method to prepare a one-dimensional lithium sodium titanate NaLiTiO ₃ nanowire material.

Contents of the invention

The purpose of the present invention is to solve the problem of poor electrochemical performance of the existing lithium sodium titanate negative electrode material, and to provide a preparation method of lithium sodium titanate NaLiTiO ₃ nanowires, which are negative electrode materials for lithium ion batteries.

The technical solution adopted by the present invention to solve the above technical problems is: a lithium sodium titanate nanowire, the chemical formula of which is NaLiTiO ₃ .

The present invention also provides a preparation method of lithium sodium titanate nanowires, the preparation method comprising:

Sodium salt was dissolved in dimethylformamide (DMF) to form solution A;

Dissolving lithium salt in absolute ethanol to form solution B;

Dissolving the titanium salt in dimethylformamide (DMF) to form a solution C;

Mix solutions A, B, and C, add glacial acetic acid and polymers, and stir for 2 hours to form a clear solution D. The molar ratio of Na, Li, and Ti elements in solution D is 1:1:3～1:1.5:3.5;

Electrospinning the clarified solution D at a voltage of 15-20kV and a flow rate of 0.8-1.2mL/h;

Dry the obtained electrospinning product in an oven at 60-90°C for 4 hours;

The dried electrostatic spinning product is transferred to a muffle furnace, and sintered at 600-800° C. for 3-6 hours to obtain lithium sodium titanate nanowires.

Preferably, the sodium salt is one or a combination of NaCH ₃ COO and NaHCO ₃ , the lithium salt is one or a combination of several of LiF, LiCH ₃ COO and LiNO ₃ , The titanium salt is isopropyl titanate, and the polymer is polyvinyl alcohol (PVA).

The one-dimensional lithium sodium titanate NaLiTiO ₃ nanowire material synthesized by the present invention has excellent performance, has higher initial discharge specific capacity and better capacity retention rate, and the initial discharge specific capacity is 80mAh g ^-1 , after 800 cycles of charging and discharging , The capacity retention rate is not less than 90%.

Description of drawings

Fig. 1 is lithium sodium titanate NaLiTiO that the present invention makes The XRD figure _of nanowire;

Fig. 2 is the SEM image of lithium sodium titanate NaLiTiO ₃ nanowires prepared in the present invention.

detailed description

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Example 1

Dissolve 0.15 mmol of NaCH ₃ COO in 2 mL of dimethylformamide (DMF) to form solution A; dissolve 0.15 mmol of LiCH ₃ COO in 5 mL of absolute ethanol to form solution B; dissolve 0.3 mmol of isopropyl titanate in 3 mL Dimethylformamide (DMF) to form solution C; mix solutions A, B, and C evenly, add 2 mL of glacial acetic acid and 1.2 g of polyvinyl alcohol, and stir for 2 hours to form a clear solution D; put the clear solution D under voltage Electrospinning was performed at 15kv and a flow rate of 0.8mL/h; the obtained electrospinning product was dried in a 60°C oven for 4h; the dried electrospinning product was transferred to a muffle furnace and sintered at 600°C for 6h. Lithium ion battery negative electrode material sodium lithium titanate NaLiTiO ₃ nanowires are obtained. The nanowires were characterized by powder diffraction (XRD), as shown in FIG. 1 . The morphology of the nanowires was observed with a scanning electron microscope, as shown in FIG. 2 .

Example 2

Dissolve 0.15 mmol of NaHCO in ₂ mL of dimethylformamide (DMF) to form solution A; dissolve 0.225 mmol of LiF in 5 mL of absolute ethanol to form solution B; dissolve 0.525 mmol of isopropyl titanate in 3 mL Dimethylformamide (DMF) to form solution C; mix solutions A, B, and C evenly, add 1.5mL glacial acetic acid and 1.1g polyvinyl alcohol, stir for 2 hours, and form a clear solution D; put the clear solution D in Electrospinning was carried out at a voltage of 20kv and a flow rate of 1.2mL/h; the obtained electrospinning product was dried in an oven at 90°C for 4h; the dried electrospinning product was transferred to a muffle furnace and sintered at 800°C for 3h , to obtain lithium sodium titanate NaLiTiO ₃ nanowires as the negative electrode material of lithium ion battery.

Example 3

Dissolve 0.15 mmol of NaCH ₃ COO in 2 mL of dimethylformamide (DMF) to form solution A; dissolve 0.15 mmol of LiNO ₃ in 5 mL of absolute ethanol to form solution B; dissolve 0.45 mmol of isopropyl titanate In dimethylformamide (DMF), form a solution C; mix solutions A, B, and C evenly, add 1.5mL glacial acetic acid and 1.2g polyvinyl alcohol, stir for 2 hours, and form a clear solution D; put the clear solution in Electrospinning was carried out at a voltage of 18kv and a flow rate of 1.0mL/h; the obtained electrospinning product was dried in an oven at 80°C for 4h; the dried electrospinning product was transferred to a muffle furnace and sintered at 700°C for 5h , to obtain lithium sodium titanate NaLiTiO ₃ nanowires as the negative electrode material of lithium ion battery.

Example 4

Dissolve 0.15 mmol of NaHCO ₃ in 2 mL of dimethylformamide (DMF) to form solution A; dissolve 0.2 mmol of LiCH ₃ COO in 5 mL of absolute ethanol to form solution B; dissolve 0.50 mmol of isopropyl titanate Add 3mL dimethylformamide (DMF) to form solution C; mix solutions A, B, and C evenly, add 1.5mL glacial acetic acid and 1.2g polyvinyl alcohol, stir for 2 hours, and form clear solution D; Electrospinning was performed at a voltage of 16kv and a flow rate of 0.6mL/h; the obtained electrospinning product was dried in an oven at 90°C for 4h; the dried electrospinning product was transferred to a muffle furnace and sintered at 600°C 6h, lithium sodium titanate NaLiTiO ₃ nanowires, which are the negative electrode material for lithium ion batteries, were obtained.

Claims (1)

1. a kind of preparation method of sodium lithium titanate nano wire, it is characterised in that the preparation method includes：

Sodium acetate or sodium acid carbonate are dissolved in DMF, solution A is formed；

One or more in lithium fluoride, lithium acetate or lithium nitrate are dissolved in absolute ethyl alcohol, solution B is formed；

Isopropyl titanate is dissolved in DMF, solution C is formed；

Glacial acetic acid and polyvinyl alcohol are added after solution A, B, C are mixed, 2h is stirred, Na, Li in the solution D of clarification, solution D is formed Mol ratio with Ti elements is 1:1:2 or 1:1.5:3.5 or 1:1:3 or 3:4:10；

By the solution D of clarification under 15~20kV voltages and 0.8~1.2mL/h flow rates electrostatic spinning；

Obtained electrostatic spinning product is put in 60~90 DEG C of oven drying 4h；

Dried electrostatic spinning product is transferred in Muffle furnace, 3~6h is sintered at 600~800 DEG C, obtains the lithium titanate Sodium nano wire；

The sodium lithium titanate nano wire is used as lithium ion battery negative material；

The chemical formula of the sodium lithium titanate nano wire is NaLiTiO₃。