阅读说明：本技术 一种纳米带钛酸锂@砭石复合纤维材料的制备及产品和应用 (Preparation of nanobelt lithium titanate @ stone needle composite fiber material, product and application ) 是由 方彦雯 方志财 于 2021-09-02 设计创作，主要内容包括：本发明涉及一种锂离子电池负极材料的制备方法,特别是涉及一种纳米带钛酸锂@砭石复合纤维材料的制备方法。它包括以下步骤：1)将有机钛盐溶于N,N-二甲基甲酰胺和醇混合液中,得溶液A；2)将溶液A在180～240℃反应15～20 h,得二氧化钛纳米片；3)将二氧化钛纳米片和砭石粉混合配比置于氢氧化锂溶液中反应,干燥,得前驱体；4)将前驱体在惰性气氛中300～400℃煅烧2～5 h得纳米带钛酸锂@砭石粉；5)将纳米带钛酸锂@砭石粉和壳聚糖溶解于极性溶液制成均匀纺丝溶液；6)将纺丝液用静电纺丝装置进行纺丝,获得纳米带钛酸锂@砭石复合纤维材料；本发明材料的电化学性能较高。(The invention relates to a preparation method of a lithium ion battery cathode material, in particular to a preparation method of a nanobelt lithium titanate @ stone needle composite fiber material. It comprises the following steps: 1) dissolving organic titanium salt in a mixed solution of N, N-dimethylformamide and alcohol to obtain a solution A; 2) reacting the solution A at 180-240 ℃ for 15-20 h to obtain a titanium dioxide nanosheet; 3) mixing and proportioning a titanium dioxide nanosheet and stone needle powder, placing the mixture in a lithium hydroxide solution for reaction, and drying to obtain a precursor; 4) calcining the precursor in an inert atmosphere at 300-400 ℃ for 2-5 h to obtain nanobelt lithium titanate @ stone needle powder; 5) dissolving nano-belt lithium titanate @ stone needle powder and chitosan in a polar solution to prepare a uniform spinning solution; 6) spinning the spinning solution by using an electrostatic spinning device to obtain a nanobelt lithium titanate @ stone needle composite fiber material; the electrochemical performance of the material is high.)

1. A preparation method of a nanobelt lithium titanate @ stone needle composite fiber material is characterized by comprising the following steps of:

1) dissolving organic titanium salt in a mixed solution of N, N-dimethylformamide and alcohol, wherein the volume ratio of the three is 1-4: 2-8: 10-20; stirring uniformly to obtain a solution A;

2) reacting the solution A at 180-240 ℃ for 15-20 h, cooling, and performing first-stage washing and first-stage drying to obtain a titanium dioxide nanosheet;

3) titanium dioxide nanosheets and stone needle powder are mixed according to the mass ratio of 50-60: 1-2, mixing and proportioning, placing in a lithium hydroxide solution, and uniformly stirring; reacting for 8-10 h at 120-160 ℃, cooling to room temperature, and performing second-stage washing and second-stage drying to obtain a precursor;

4) calcining the precursor in an inert atmosphere at 300-400 ℃ for 2-5 h to obtain nanobelt lithium titanate @ stone needle powder;

5) dissolving nano-belt lithium titanate @ stone needle powder and chitosan into a polar solution, stirring, and fully mixing to prepare a uniform spinning solution; the concentration of the spinning solution is 2% -60%;

6) and spinning the spinning solution by using an electrostatic spinning device to obtain the nano-belt lithium titanate @ stone needle composite fiber material.

2. The preparation method of the nanobelt lithium titanate @ stone needle composite fiber material according to claim 1, characterized in that: the first-stage washing and the second-stage washing are washing for 3-5 times by using deionized water and an organic solvent; the first stage drying and the second stage drying are carried out in an oven at 60-80 ℃ overnight.

3. The preparation method of the nanobelt lithium titanate @ stone needle composite fiber material according to claim 2, characterized in that: in the step 1), the organic titanium salt is one or a combination of tetrabutyl titanate, isopropyl titanate and ethyl titanate; the alcohol is one or combination of isopropanol, n-butanol or propanol.

4. The preparation method of the nanobelt lithium titanate @ stone needle composite fiber material according to claim 3, characterized in that: in the step 2), the organic solvent is one or a combination of absolute ethyl alcohol and acetone.

5. The preparation method of the nanobelt lithium titanate @ stone needle composite fiber material according to claim 4, characterized in that: in the step 4), the inert atmosphere is one or a combination of nitrogen and argon.

6. The preparation method of the nanobelt lithium titanate @ stone needle composite fiber material according to claim 5, characterized in that: in the step 5), the polar solvent is one or a combination of formic acid, glacial acetic acid or trifluoroacetic acid; the deacetylation degree of the chitosan is 80-100%.

7. The preparation method of the nanobelt lithium titanate @ stone needle composite fiber material according to claim 6, characterized in that: in the step 6), the technological parameters of electrostatic spinning are as follows: 1-50 kV, the receiving distance is 1-50 cm, and the solution flow is 0.01-20 mL/h.

8. The preparation method of the nanobelt lithium titanate @ stone needle composite fiber material according to any one of claims 1 to 7, which is characterized by comprising the following specific steps:

1) dissolving organic titanium salt in a mixed solution of N, N-dimethylformamide and alcohol, wherein the volume ratio of the three is 2 mL to 5 mL to 15 mL; stirring the mixture for 1 to 2 hours until the mixture is uniform to obtain a solution A;

2) transferring the solution A into a reaction kettle, reacting for 15-20 h at 180-240 ℃, cooling to room temperature, washing for 3-5 times by using deionized water and an organic solvent, and drying in an oven at 60-80 ℃ overnight to obtain a titanium dioxide nanosheet;

3) placing titanium dioxide nanosheets and stone needle powder into a lithium hydroxide solution, and stirring for 1-2 hours until the titanium dioxide nanosheets and the stone needle powder are uniform; wherein the mass ratio of the titanium dioxide nanosheet to the stone needle powder is 50-60: 1-2; transferring the mixture into a reaction kettle, reacting for 8-10 h at 120-160 ℃, cooling to room temperature, washing for 3-5 times by using deionized water and an organic solvent, and drying in an oven at 60-80 ℃ overnight to obtain a precursor;

4) calcining the precursor in a muffle furnace for 2-5 h at 300-400 ℃ in an inert atmosphere to obtain nano-belt lithium titanate @ stone needle powder;

5) dissolving 35-40 parts by weight of nanobelt lithium titanate @ stone needle powder and 20-30 parts by weight of chitosan into 50-60 parts by weight of polar solution, magnetically stirring at room temperature for 30-60 min, and fully mixing to prepare uniform spinning solution; the concentration of the spinning solution is 2% -60%;

6) and spinning the spinning solution by using an electrostatic spinning device to obtain the nano-belt lithium titanate @ stone needle composite fiber material.

9. The preparation method of the nanobelt lithium titanate @ stone needle composite fiber material according to claim 8, characterized in that: the electrostatic spinning device comprises an electrostatic spinning machine body (1), an injection nozzle (11) is fixedly mounted at the top of the inner wall of the electrostatic spinning machine body (1), a fixing frame (2) is fixedly mounted at the bottom of the inner wall of the electrostatic spinning machine body (1) through a bolt, a threaded hole (21) is formed in one side of the inner wall of the fixing frame (2), a roller (3) is contacted with the bottom of the inner wall of the electrostatic spinning machine body (1), a connecting frame (31) is rotatably sleeved at the top of the outer wall of the roller (3), a motor (32) is fixedly mounted at the top of the connecting frame (31) through a bolt, a rotating rod (33) is welded at the output end of the motor (32), a positioning thread (34) is formed in the outer wall of one end, close to the motor (32), of the rotating rod (33), the positioning thread (34) is sleeved in the threaded hole (21), a rotating ring (35) is fixedly sleeved at the middle part of the outer wall of the electrostatic spinning machine body (1), the utility model discloses a syringe, including swivel (35) outer wall, support frame (4), horizontal pole (41) outer wall fixed cover, injection shower nozzle (11) output is just to receiving roller (42), support frame (41) one end runs through support frame (4), horizontal pole (41) one end outer wall fixed cover has second gear (43), second gear (43) bottom meshing is connected with first gear (36), first gear (36) fixed cover is in bull stick (33) outer wall middle part.

10. Application of a product obtained by the preparation method of the nanobelt lithium titanate @ stone needle composite fiber material according to any one of claims 1 to 9 in a lithium battery material.

Technical Field

The invention relates to a preparation method of a lithium ion battery cathode material, in particular to a preparation method of a nanobelt lithium titanate @ stone needle composite fiber material.

Background

With the rapid development of smaller, lighter and higher performance electronic and communication devices, there is an increasing demand for the performance of batteries that provide power to these devices, particularly with respect to energy. However, the specific capacities of lithium ion batteries and MH/Ni batteries which are commercialized at present are difficult to be improved continuously. Therefore, the development of batteries with higher specific energy is urgently required. Lithium ion secondary batteries have been widely used as high specific energy chemical power sources in the fields of mobile communication, notebook computers, video cameras, portable instruments and meters, and the like, and have rapidly developed into one of the most important secondary batteries at present. Lithium ion batteries, which are the latest generation of green high-energy storage batteries, have been rapidly developed in the early 90 s of the 20 th century, and are favored because of their advantages of high voltage, high energy density, long cycle life, little environmental pollution, and the like.

At present, carbon anode materials are mostly adopted as commercial lithium ion battery anode materials, but the carbon anode materials have some defects: the electrolyte reacts with the electrolyte in the first discharging process to form a surface passivation film, so that the consumption of the electrolyte and the first coulombic efficiency are low; the carbon electrode has a similar electrode potential to that of metallic lithium, and when the battery is overcharged, metallic lithium may be precipitated on the surface of the carbon electrode to form dendrite, which may cause short circuit and cause safety problems. The search for new lithium ion negative electrode materials becomes a hot point of research. The spinel type lithium titanate is a zero-strain material, has good cycle performance, does not react with electrolyte, has a stable charging and discharging voltage platform, higher safety, low price and easier preparation, and is a very potential power type lithium ion battery cathode material. At the same time, the material has some disadvantages, Li₄Ti₅O₁₂The conductivity of the material is very low, the material is almost insulating, the performance under high multiplying power is poor, and the material is greatly limited if the material is applied to the fields of power vehicles, large energy storage batteries and the like. Thus, for Li₄Ti₅O₁₂The material has the defect of poor conductivity, and the research for improving the conductivity and high rate performance of the material is particularly important. Currently, the commonly used modification method is to perform nanocrystallization, coating or doping to primarily improve the performance of the electrode. Preparation of nanosized Li₄Ti₅O₁₂Reducing the size of material particles and shortening Li⁺Diffusion path of (2), reduction of Li⁺The electrochemical performance of the material is improved by the diffusion resistance and the electrode polarization slowing, but the nano particles are easy to agglomerate in the charging and discharging process. As charging and discharging progress, the electrochemical properties of the material may decrease.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a preparation method of a nanobelt lithium titanate @ stone needle composite fiber material.

Yet another object of the present invention is to: the nanobelt lithium titanate @ stone needle composite fiber material prepared by the method is provided.

Yet another object of the present invention is to: applications of the above products are provided.

The first technical purpose of the invention is realized by the following technical scheme:

a preparation method of a nanobelt lithium titanate @ stone needle composite fiber material comprises the following steps:

1) dissolving organic titanium salt in a mixed solution of N, N-dimethylformamide and alcohol, wherein the volume ratio of the three is 1-4: 2-8: 10-20; stirring uniformly to obtain a solution A;

2) reacting the solution A at 180-240 ℃ for 15-20 h, cooling, and performing first-stage washing and first-stage drying to obtain a titanium dioxide nanosheet;

3) titanium dioxide nanosheets and stone needle powder are mixed according to the mass ratio of 50-60: 1-2, mixing and proportioning, placing in a lithium hydroxide solution, and uniformly stirring; reacting for 8-10 h at 120-160 ℃, cooling to room temperature, and performing second-stage washing and second-stage drying to obtain a precursor;

4) calcining the precursor in an inert atmosphere at 300-400 ℃ for 2-5 h to obtain nanobelt lithium titanate @ stone needle powder;

5) dissolving nano-belt lithium titanate @ stone needle powder and chitosan into a polar solution, stirring, and fully mixing to prepare a uniform spinning solution; the concentration of the spinning solution is 2% -60%;

6) and spinning the spinning solution by using an electrostatic spinning device to obtain the nano-belt lithium titanate @ stone needle composite fiber material.

According to the preparation method of the nanobelt lithium titanate @ stone needle composite fiber material, the nanobelt lithium titanate material has a large specific surface area and can be fully contacted with an electrolyte, the electrochemical performance of the material is improved, the stone needle powder is rich in trace elements such as magnesium and iron and rare earth elements such as strontium, yttrium, copper and chromium, and a small amount of trace elements and rare earth elements can be doped into lithium titanate lattices in the calcining process, so that the electrochemical performance of the material is improved.

Preferably, the first-stage washing and the second-stage washing are washing for 3-5 times by using deionized water and an organic solvent; the first stage drying and the second stage drying are carried out in an oven at 60-80 ℃ overnight.

The selection of the washing solvent and the control of the drying temperature and the drying time influence the performance of the reaction product of the stone needle powder, carbon dioxide and lithium hydroxide in the precursor, and the specific selection and the control of the invention can help obtain the nano-belt lithium titanate @ stone needle powder with larger specific surface area and better doping performance of trace elements and rare earth elements in the subsequent calcining process.

Preferably, in the step 1), the organic titanium salt is one or a combination of tetrabutyl titanate, isopropyl titanate and ethyl titanate; the alcohol is one or combination of isopropanol, n-butanol or propanol.

Preferably, in the step 2), the organic solvent is one or a combination of absolute ethyl alcohol and acetone.

Preferably, in the step 4), the inert atmosphere is one or a combination of nitrogen and argon.

Preferably, in the step 5), the polar solvent is one or a combination of formic acid, glacial acetic acid or trifluoroacetic acid; the deacetylation degree of the chitosan is 80-100%.

The selection of the polar solvent and the control of the deacetylation degree of the chitosan influence the performance of the spinning solution, and the specific selection and control of the preparation method can help obtain the nanobelt lithium titanate @ stone needle powder with better electrochemical performance in the subsequent spinning process.

Preferably, in the step 6), the electrostatic spinning process parameters are as follows: 1-50 kV, the receiving distance is 1-50 cm, and the solution flow is 0.01-20 mL/h.

The electrostatic spinning process parameter control has influence on the performance of the nanobelt lithium titanate @ stone needle composite fiber material, and the specific selection and control of the method can obtain the nanobelt lithium titanate @ stone needle powder with better electrochemical performance.

A preparation method of a nanobelt lithium titanate @ stone needle composite fiber material comprises the following specific steps:

1) dissolving organic titanium salt in a mixed solution of N, N-dimethylformamide and alcohol, wherein the volume ratio of the three is 2 mL to 5 mL to 15 mL; stirring the mixture for 1 to 2 hours until the mixture is uniform to obtain a solution A;

2) transferring the solution A into a reaction kettle, reacting for 15-20 h at 180-240 ℃, cooling to room temperature, washing for 3-5 times by using deionized water and an organic solvent, and drying in an oven at 60-80 ℃ overnight to obtain a titanium dioxide nanosheet;

3) placing titanium dioxide nanosheets and stone needle powder into a lithium hydroxide solution, and stirring for 1-2 hours until the titanium dioxide nanosheets and the stone needle powder are uniform; wherein the mass ratio of the titanium dioxide nanosheet to the stone needle powder is 50-60: 1-2; transferring the mixture into a reaction kettle, reacting for 8-10 h at 120-160 ℃, cooling to room temperature, washing for 3-5 times by using deionized water and an organic solvent, and drying in an oven at 60-80 ℃ overnight to obtain a precursor;

4) calcining the precursor in a muffle furnace for 2-5 h at 300-400 ℃ in an inert atmosphere to obtain nano-belt lithium titanate @ stone needle powder;

5) dissolving 35-40 parts by weight of nanobelt lithium titanate @ stone needle powder and 20-30 parts by weight of chitosan into 50-60 parts by weight of polar solution, magnetically stirring at room temperature for 30-60 min, and fully mixing to prepare uniform spinning solution; the concentration of the spinning solution is 2% -60%;

6) and spinning the spinning solution by using an electrostatic spinning device to obtain the nano-belt lithium titanate @ stone needle composite fiber material.

Preferably, the electrostatic spinning device comprises an electrostatic spinning machine body, an injection nozzle is fixedly installed at the top of the inner wall of the electrostatic spinning machine body, a fixing frame is fixedly installed at the bottom of the inner wall of the electrostatic spinning machine body through a bolt, a threaded hole is formed in one side of the inner wall of the fixing frame, a roller is contacted with the bottom of the inner wall of the electrostatic spinning machine body, a connecting frame is rotatably sleeved at the top of the outer wall of the roller, a motor is fixedly installed at the top of the connecting frame through a bolt, a rotating rod is welded at the output end of the motor, a positioning thread is formed in the outer wall of one end, close to the motor, of the rotating rod, the positioning thread is sleeved in the threaded hole, a rotating ring is fixedly sleeved at the middle part of the outer wall of the electrostatic spinning machine body, a supporting frame is rotatably sleeved at the outer wall of the rotating ring, a cross rod is rotatably sleeved at one side of the inner wall of the supporting frame, a receiving roller is fixedly sleeved at the outer wall of the cross rod, and the output end of the injection nozzle is opposite to the receiving roller, the support frame is run through to horizontal pole one end, horizontal pole one end outer wall fixed cover has the second gear, the meshing of second gear bottom is connected with first gear, the fixed cover of first gear is in the middle part of bull stick outer wall.

The receiving roller can transversely move and rotate at the same time by controlling the motor, and two motion states of the receiving roller can be completed only by a single motor; through the motor just reversing, under screw hole and location screw are spacing, can drive the receiving roll on the support frame and carry out lateral shifting, make when injection shower nozzle is limited to spinning spray range, through removing the receiving roll, make the spinning gathering area bigger on the receiving roll, suitable bulk production. After the motor of the invention is operated, the receiving roller is driven to rotate by the components such as the rotating rod, the two gears and the like, so that the spinning can be more uniformly distributed on the receiving roller during electrostatic spinning, and the formation of fiber materials is facilitated; thereby forming the nanobelt lithium titanate @ stone needle composite fiber material with better electrochemical performance.

As a preferred technical scheme of the invention, one end of the rotating rod penetrates through the fixing frame, and the limiting rod is welded in the fixing frame.

As a preferred technical scheme of the invention, the bottom end of the support frame is slidably sleeved on the outer wall of the limiting rod, and the rotating ring and the first gear are both positioned right above the limiting rod.

As a preferable technical scheme of the invention, the bottom of the support frame is contacted with the bottom of the inner wall of the fixed frame, and the rotating ring is positioned between the positioning thread and the first gear.

As a preferred technical solution of the present invention, the receiving roller is located inside the supporting frame, and the second gear is located outside the supporting frame.

As a preferred technical scheme of the invention, the electrostatic spinning machine body and the motor are both electrically connected with an external power supply, the rotating ring is in a circular ring shape, and the fixing frame is in a U-shaped shape.

The second technical purpose of the invention is realized by the following technical scheme:

the invention provides a nanobelt lithium titanate @ stone needle composite fiber material which is prepared according to any one of the methods.

The third technical purpose of the invention is realized by the following technical scheme:

the invention provides an application of a preparation method of a nanobelt lithium titanate @ stone needle composite fiber material in a lithium battery material.

In conclusion, the invention has the following beneficial effects:

1. according to the preparation method of the nanobelt lithium titanate @ stone needle composite fiber material, the nanobelt lithium titanate material has a large specific surface area and can be fully contacted with an electrolyte, so that the electrochemical performance of the material is improved, the stone needle powder is rich in trace elements such as magnesium and iron and rare earth elements such as strontium, yttrium, copper and chromium, and a small amount of trace elements and rare earth elements can be doped into lithium titanate lattices in the calcining process, so that the electrochemical performance of the material is improved;

2. the selection of the washing solvent and the control of the drying temperature and the drying time influence the performance of the reaction product of the stone needle powder, carbon dioxide and lithium hydroxide in the precursor, and the specific selection and the control of the invention can help obtain the nano-belt lithium titanate @ stone needle powder with larger specific surface area and better doping performance of trace elements and rare earth elements in the subsequent calcining process.

3. The selection of a polar solvent and the control of the deacetylation degree of chitosan influence the performance of the spinning solution, and the specific selection and control of the method can help obtain the nanobelt lithium titanate @ stone needle powder with better electrochemical performance in the subsequent spinning process;

4. the electrostatic spinning process parameter control influences the performance of the nanobelt lithium titanate @ stone needle composite fiber material, and the specific selection and control of the method can obtain nanobelt lithium titanate @ stone needle powder with better electrochemical performance;

5. the receiving roller can transversely move and rotate at the same time by controlling the motor, and two motion states of the receiving roller can be completed only by a single motor; through the motor just reversing, under screw hole and location screw are spacing, can drive the receiving roll on the support frame and carry out lateral shifting, make when injection shower nozzle is limited to spinning spray range, through removing the receiving roll, make the spinning gathering area bigger on the receiving roll, suitable bulk production. After the motor of the invention is operated, the receiving roller is driven to rotate by the components such as the rotating rod, the two gears and the like, so that the spinning can be more uniformly distributed on the receiving roller during electrostatic spinning, and the formation of fiber materials is facilitated; the electrostatic spinning device influences the performance of the nanobelt lithium titanate @ stone needle composite fiber material, and the specific device can obtain nanobelt lithium titanate @ stone needle powder with better electrochemical performance.

Drawings

FIG. 1 is an SEM image of a nanobelt lithium titanate @ stone needle composite fiber material in example 1;

FIG. 2 is a charge-discharge performance diagram of the nanobelt lithium titanate @ stone needle composite fiber material of example 2;

FIG. 3 is a cycle life diagram of the nanobelt lithium titanate @ stone needle composite fiber material of example 3;

FIG. 4 is a front view showing the overall structure of the electrospinning device of the present invention;

FIG. 5 is a front sectional view showing the overall structure of the electrospinning device of the present invention;

FIG. 6 is an enlarged view of the structure A of FIG. 5 according to the present invention;

FIG. 7 is an enlarged view of the structure B of FIG. 6 according to the present invention;

FIG. 8 is a front view of a swivel of an electrospinning apparatus of the present invention;

in the figure, 1, an electrostatic spinning machine body; 11. an injection nozzle; 2. a fixed mount; 21. a threaded hole; 22. a limiting rod; 3. a roller; 31. a connecting frame; 32. a motor; 33. a rotating rod; 34. positioning the screw thread; 35. rotating the ring; 36. a first gear; 4. a support frame; 41. a cross bar; 42. a receiving roller; 43. a second gear.

Detailed Description

The present invention is described in detail by the following specific examples, but the scope of the present invention is not limited to these examples.

Example 1

Dissolving tetrabutyl titanate in a mixed solution of N, N-dimethylformamide and isopropanol, wherein the volume ratio of the tetrabutyl titanate to the N, N-dimethylformamide to the isopropanol is 2 mL to 5 mL to 15 mL; stirring for 1 hour to be uniform by magnetic force to obtain solution A; transferring the A into a reaction kettle, reacting for 20 h at 180 ℃, cooling to room temperature, washing for 3 times by using deionized water and ethanol, and drying in an oven at 60 ℃ overnight to obtain a titanium dioxide nanosheet; placing titanium dioxide nanosheets and stone needle powder in a lithium hydroxide solution, and stirring for 1 h until the titanium dioxide nanosheets and the stone needle powder are uniform; wherein the mass ratio of the titanium dioxide nanosheet to the stone needle powder is 50: 1; transferring the mixture into a reaction kettle to react for 8 hours at 160 ℃, cooling the mixture to room temperature, washing the mixture for 5 times by using deionized water and ethanol, and drying the mixture in an oven at 80 ℃ overnight to obtain a precursor; calcining the precursor in a muffle furnace at 400 ℃ for 2 h in a nitrogen atmosphere to obtain nano-belt lithium titanate @ stone needle powder; dissolving 40 parts by weight of nanobelt lithium titanate @ stone needle powder and 20 parts by weight of chitosan into 55 parts by weight of glacial acetic acid solution, magnetically stirring at room temperature for 60 min, and fully mixing to prepare uniform spinning solution; wherein the deacetylation degree of the chitosan is 90%, and the concentration of the spinning solution is 10%; spinning the spinning solution by using a conventional electrostatic spinning device, wherein the process parameters of electrostatic spinning are as follows: and (3) 20 kilovolts, the acceptance distance is 25 cm, and the solution flow is 5 mL/h, so that the nanobelt lithium titanate @ stone needle composite fiber material is obtained. FIG. 1 is an SEM image of a nanobelt lithium titanate @ stone needle composite fiber material. The fiber diameter is 186-246 nm. Through detection, the first discharge specific capacity is 175 mAh/g, the second discharge specific capacity is 168mAh/g, and the discharge specific capacity is 156mAh/g after 100 times of circulation.

Example 2

Dissolving isopropyl titanate in a mixed solution of N, N-dimethylformamide and N-butanol, wherein the volume ratio of the isopropyl titanate to the N, N-dimethylformamide to the N-butanol is 2 mL to 5 mL to 15 mL; stirring for 2 hours until the solution is uniform by magnetic force to obtain solution A; transferring the A into a reaction kettle, reacting at 180 ℃ for 20 h, cooling to room temperature, washing for 3 times by using deionized water and acetone, and drying in an oven at 80 ℃ overnight to obtain a titanium dioxide nanosheet; placing titanium dioxide nanosheets and stone needle powder in a lithium hydroxide solution, and stirring for 2 hours until the titanium dioxide nanosheets and the stone needle powder are uniform; wherein the mass ratio of the titanium dioxide nanosheet to the stone needle powder is 60: 1; transferring the mixture into a reaction kettle to react for 10 h at 130 ℃, cooling to room temperature, washing for 3 times by using deionized water and ethanol, and drying in an oven at 80 ℃ overnight to obtain a precursor; calcining the precursor in a muffle furnace at 300 ℃ for 5 hours in a nitrogen atmosphere to obtain nano-belt lithium titanate @ stone needle powder; dissolving 35 parts by weight of nanobelt lithium titanate @ stone needle powder and 20 parts by weight of chitosan in 50 parts by weight of glacial acetic acid solution, magnetically stirring at room temperature for 60 min, and fully mixing to prepare uniform spinning solution; wherein the deacetylation degree of chitosan is 80%, and the concentration of spinning solution is 15%; spinning the spinning solution by using a conventional electrostatic spinning device, wherein the process parameters of electrostatic spinning are as follows: and (3) 20 kilovolts, the acceptance distance is 20 centimeters, and the solution flow is 10 mL/h, so that the nanobelt lithium titanate @ stone needle composite fiber material is obtained. FIG. 2 is a charge-discharge performance diagram of the nanobelt lithium titanate @ stone needle composite fiber material. Under the condition of 0.5C, the first charge-discharge specific capacity is 175 mAh/g and 178mAh/g respectively. Through detection, the first discharge specific capacity is 173mAh/g, the second discharge specific capacity is 166 mAh/g, and the discharge specific capacity is 153mAh/g after 100 times of circulation.

Example 3

Dissolving ethyl titanate in a mixed solution of N, N-dimethylformamide and N-butanol, wherein the volume ratio of the ethyl titanate to the N, N-dimethylformamide to the N-butanol is 2 mL to 5 mL to 15 mL; stirring for 2 hours until the solution is uniform by magnetic force to obtain solution A; transferring the A into a reaction kettle, reacting for 15 h at 240 ℃, cooling to room temperature, washing for 3 times by using deionized water and acetone, and drying in an oven at 80 ℃ overnight to obtain a titanium dioxide nanosheet; placing titanium dioxide nanosheets and stone needle powder in a lithium hydroxide solution, and stirring for 2 hours until the titanium dioxide nanosheets and the stone needle powder are uniform; wherein the mass ratio of the titanium dioxide nanosheet to the stone needle powder is 60: 1; transferring the mixture into a reaction kettle to react for 8 hours at 120 ℃, cooling the mixture to room temperature, washing the mixture for 3 times by using deionized water and acetone, and drying the mixture in an oven at 80 ℃ overnight to obtain a precursor; calcining the precursor in a muffle furnace at 350 ℃ for 2 h in an argon atmosphere to obtain nano-belt lithium titanate @ stone needle powder; dissolving 40 parts by weight of nanobelt lithium titanate @ stone needle powder and 20 parts by weight of chitosan in 55 parts by weight of trifluoroacetic acid, magnetically stirring at room temperature for 60 min, and fully mixing to prepare a uniform spinning solution; wherein the deacetylation degree of chitosan is 95%, and the concentration of the spinning solution is 20%; spinning the spinning solution by using a conventional electrostatic spinning device, wherein the process parameters of electrostatic spinning are as follows: 15 kilovolts, the acceptance distance is 20 centimeters, the solution flow is 15 mL/h, and the nanobelt lithium titanate @ stone needle composite fiber material is obtained. FIG. 3 is a cycle life diagram of the nanobelt lithium titanate @ stone needle composite fiber material. The first discharge specific capacity is 178mAh/g, the second discharge specific capacity is 170mAh/g, and the discharge specific capacity is 158 mAh/g after 100 times of circulation.

Example 4

The same as example 1, except that the electrospinning was carried out using the specific electrospinning apparatus of the present invention: the electrospinning apparatus shown in fig. 4-8: the electrostatic spinning machine comprises an electrostatic spinning machine body 1, wherein the electrostatic spinning machine body 1 is an existing electrostatic spinning machine, internal mechanisms of the electrostatic spinning machine body 1 are disclosed, and redundant description is omitted, an injection nozzle 11 is fixedly installed at the top of the inner wall of the electrostatic spinning machine body 1, so that electrostatic spinning can be conveniently carried out by using the injection nozzle 11, a fixing frame 2 is fixedly installed at the bottom of the inner wall of the electrostatic spinning machine body 1 through bolts, the electrostatic spinning machine body 1 can conveniently fix the fixing frame 2, and a threaded hole 21 is formed in one side of the inner wall of the fixing frame 2;

the bottom of the inner wall of the electrostatic spinning machine body 1 is contacted with the roller 3, the electrostatic spinning machine body 1 can support the roller 3, the top of the outer wall of the roller 3 is rotatably sleeved with the connecting frame 31, the connecting frame 31 can limit the roller 3, the top of the connecting frame 31 is fixedly provided with the motor 32 through bolts, the connecting frame 31 can support the motor 32, when the motor 32 moves transversely, the connecting frame 31 and the roller 3 can improve the stability of the motor 32 when moving, the roller 3 can reduce the resistance of the motor 32 when moving through rolling, the output end of the motor 32 is welded with the rotating rod 33, the motor 32 can drive the rotating rod 33 to rotate after running, and the motor 32 can rotate forwards and backwards, which is the prior art and is not described in more detail herein;

the outer wall of one end of the rotating rod 33 close to the motor 32 is provided with a positioning thread 34, the positioning thread 34 is in threaded sleeve in the threaded hole 21, one end of the rotating rod 33 is in threaded sleeve in the threaded hole 21 through the positioning thread 34, the positioning thread 34 and the threaded hole 21 are convenient for supporting and limiting the rotating rod 33, the middle part of the outer wall of the electrostatic spinning machine body 1 is fixedly sleeved with a rotating ring 35, the outer wall of the rotating ring 35 is rotatably sleeved with a support frame 4, the rotating ring 35 can be used for connecting the rotating rod 33 with the support frame 4, the rotating rod 33 is matched with a limiting rod 22 to limit the support frame 4, the support frame 4 can move transversely along with the rotating rod 33 and cannot rotate along with the rotating rod 33, one side of the inner wall of the support frame 4 is rotatably sleeved with a cross rod 41, the outer wall of the cross rod 41 is fixedly sleeved with a receiving roller 42, the cross rod 41 can support the receiving roller 42, the output end of the injection nozzle 11 is opposite to the receiving roller 42, and is convenient for the injection nozzle 11 to spray spinning on the receiving roller 42, support frame 4 is run through to horizontal pole 41 one end, and the fixed cover of horizontal pole 41 one end outer wall has second gear 43 for second gear 42 can drive horizontal pole 41 after rotating and rotate, and second gear 43 bottom meshing is connected with first gear 36, makes first gear 36 can drive second gear 43 after rotating and rotate, and first gear 36 is fixed to be overlapped in bull stick 33 outer wall middle part, and the bull stick 33 of being convenient for drives first gear 36 after rotating and rotates.

Specifically, referring to fig. 6, one end of the rotating rod 33 penetrates through the fixing frame 2, so that the fixing frame 2 can support the rotating rod 33, and the limiting rod 22 is welded in the fixing frame 2, thereby facilitating the fixing frame 2 to support the limiting rod 22.

Specifically, referring to fig. 6, the bottom end of the supporting frame 4 is slidably sleeved on the outer wall of the limiting rod 22, so that the limiting rod 22 can limit the supporting frame 4, the supporting frame 4 can only move laterally but cannot rotate, and the rotating ring 35 and the first gear 36 are both located right above the limiting rod 22.

Specifically, referring to fig. 6, the bottom of the supporting frame 4 is in contact with the bottom of the inner wall of the fixing frame 2, so that the fixing frame 2 can limit and support the supporting frame 4, and the rotating ring 35 is located between the positioning thread 34 and the first gear 36.

Specifically, referring to fig. 6, the receiving roller 42 is located inside the supporting frame 4, so that the supporting frame 4 can shield and protect the receiving roller 42, the second gear 43 is located outside the supporting frame 4, and the second gear 42 rotates outside the supporting frame 4.

Specifically, referring to fig. 4, 6 and 8, the electrostatic spinning machine body 1 and the motor 32 are electrically connected to an external power supply, the external power supply supplies power, the rotating ring 35 is in a circular ring shape, so that the rotating ring 35 can rotate in the supporting frame 4 conveniently, and the fixing frame 2 is in a U-shape, so that the fixing frame 2 can support the rotating rod 33 conveniently.

The working principle is as follows: when in use, the motor 32 is controlled to rotate positively and negatively, the motor 32 drives the rotating rod 33 to rotate after running, at the moment, under the supporting and limiting of the threaded hole 21 and the positioning thread 34 on the rotating rod 33, the rotating rod 33 rotates and moves transversely (communicated with a rotating bolt principle), so that the motor 32, the support frame 4 and the rotating rod 33 are driven to move transversely as a whole, at the same time, under the limiting of the rotating ring 35 and the limiting rod 22, the support frame 4 can only move transversely but not rotate, because the position of the injection nozzle 11 is fixed and the injection range is fixed, the transverse movement of the support frame 4 and the receiving roller 42 can be used for increasing the spinning gathering area on the receiving roller 42, meanwhile, after the rotating rod 33 rotates, the first gear 36 and the second gear 43 can drive the cross rod 41 to rotate, the cross rod 41 can drive the receiving roller 42 to rotate in the support frame 4, and during electrostatic spinning, the receiving roller 42 is rotated, the spray spinning is more uniformly distributed on the receiving roller 42, and the connecting frame 31 and the roller 3 can support the motor 32, so that the motor 32 is more stable in operation and movement.

Through detection, the first discharge specific capacity is 188 mAh/g, the second discharge specific capacity is 175 mAh/g, and the discharge specific capacity is 170mAh/g after 100 times of circulation.

Example 5

The same as example 2 except that electrospinning was carried out using a specific electrospinning apparatus as described in example 4. Through detection, the first discharge specific capacity is 190 mAh/g, the second discharge specific capacity is 178mAh/g, and the discharge specific capacity is 172 mAh/g after 100 times of circulation.

Example 6

The same as example 3 except that electrospinning was carried out using a specific electrospinning apparatus as described in example 4. Through detection, the first discharge specific capacity is 185 mAh/g, the second discharge specific capacity is 173mAh/g, and the discharge specific capacity is 161mAh/g after 100 times of circulation.

Comparative example 1

In the same way as in example 1, different steps 1) are carried out to dissolve organic titanium salt into a mixed solution of N, N-dimethylformamide and alcohol, wherein the volume ratio of the three is 1: 9: 8; step 3), preparing titanium dioxide nanosheets and stone needle powder according to a mass ratio of 45: 3, mixing and proportioning, putting into lithium hydroxide solution, and stirring uniformly. Through detection, the first discharge specific capacity is 145 mAh/g, the second discharge specific capacity is 130 mAh/g, and the discharge specific capacity is 126mAh/g after 100 times of circulation.

Comparative example 2

The same as example 1, except that step 2) the solution A was reacted at 160 ℃ for 14 h; step 3) reacting the titanium dioxide nanosheet with the stone needle powder at 170 ℃; and step 4) calcining the precursor in an inert atmosphere at 450 ℃ to obtain the nano-belt lithium titanate @ stone needle powder. Through detection, the first discharge specific capacity is 150mAh/g, the second discharge specific capacity is 140 mAh/g, and the discharge specific capacity is 120 mAh/g after 100 times of circulation.

The above data for examples 1-6 and comparative examples 1-2 illustrate that:

1. compared with the formula or different process of the comparative example 1-2, the nanobelt lithium titanate @ stone needle powder composite fiber material prepared by the formula and process parameters of the embodiments 1-6 of the invention has better electrochemical performance;

2. compared with the nanobelt lithium titanate @ stone needle powder composite fiber material prepared by adopting a conventional electrostatic spinning device in examples 1-3, the nanobelt lithium titanate @ stone needle powder composite fiber material prepared by adopting the specific electrostatic spinning device in examples 4-6 of the invention has better electrochemical performance.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.