阅读说明：本技术 一种三维层状硼掺杂碳化钛及其制备方法和应用 (Three-dimensional layered boron-doped titanium carbide and preparation method and application thereof ) 是由 吴娜 张奇月 赵梦凡 陈新钰 于 2021-08-26 设计创作，主要内容包括：本发明提供了一种三维层状硼掺杂碳化钛及其制备方法和应用,属于锂离子电池材料技术领域。本发明通过将原材料Ti-(3)AlC-(2)刻蚀成碳化钛,然后将不同比例的碳化钛和硼酸进行水热反应,最终得到三维层状硼掺杂碳化钛。本发明得到的三维层状硼掺杂碳化钛因为成核位点硼的存在起到了均匀沉积的作用,还因为层间距小限制了沉积析出过程中锂枝晶的生长,很大程度上,提高了锂负极的安全性,库伦效率以及循环寿命,且本发明的制备方法操作简单易行,有利于大规模生产。(The invention provides three-dimensional layered boron-doped titanium carbide and a preparation method and application thereof, belonging to the technical field of lithium ion battery materials. The invention is prepared by mixing the raw material Ti 3 AlC 2 Etching to obtain titanium carbide, and then carrying out hydrothermal reaction on the titanium carbide and boric acid in different proportions to finally obtain the three-dimensional layered boron-doped titanium carbide. The three-dimensional layered boron-doped titanium carbide obtained by the invention plays a role in uniform deposition due to the existence of boron at nucleation sites, and the growth of lithium dendrites in the deposition and precipitation process is limited due to the small interlayer spacing, so that the safety, the coulombic efficiency and the cycle life of a lithium cathode are improved to a great extentAnd (5) producing a mould.)

1. A preparation method of three-dimensional layered boron-doped titanium carbide is characterized by comprising the following steps:

1) mixing Ti₃AlC₂Reacting with LiF in HCl solution, washing the obtained product to be neutral, and drying to obtain Ti₃C₂Powder;

2) mixing Ti₃C₂Powder, water and H₃BO₃And carrying out mixed hydrothermal reaction to obtain the three-dimensional layered boron-doped titanium carbide.

2. The method according to claim 1, wherein the Ti is₃AlC₂The mass-to-volume ratio of LiF to HCl solution is 10-2000 mg: 10-3000 mg: 1-50 mL.

3. The preparation method according to claim 2, wherein the concentration of the HCl solution is 3-12 mol/L.

4. The method according to any one of claims 1 to 3, wherein the reaction temperature in step 1) is 20 to 30 ℃ and the reaction time is 1 to 72 hours.

5. The preparation method according to claim 4, wherein in the step 1), the drying temperature is 40-120 ℃ and the drying time is 4-12 h.

6. The method according to claim 5, wherein the Ti is₃C₂Powder, water and H₃BO₃The mass-to-volume ratio of (A) is 30-900 mg: 300-9000 mL: 10-800 mg.

7. The preparation method according to claim 6, wherein the temperature of the hydrothermal reaction is 20 to 400 ℃ and the time of the hydrothermal reaction is 2 to 72 hours.

8. The preparation method according to claim 7, wherein a drying treatment is further required after the hydrothermal reaction, the drying treatment temperature is 40-120 ℃, and the drying treatment time is 4-10 hours.

9. The three-dimensional layered boron-doped titanium carbide prepared by the preparation method of any one of claims 1 to 8.

10. The use of the three-dimensional layered boron-doped titanium carbide of claim 9 as a negative electrode material in a lithium ion battery.

Technical Field

The invention relates to the technical field of lithium ion battery materials, in particular to three-dimensional layered boron-doped titanium carbide and a preparation method and application thereof.

Background

In recent years, lithium ion batteries have been developed very rapidly as energy storage devices. Because the lithium ion battery has the advantages of high energy density, long cycle life, less self-discharge, no memory effect and the like, the lithium ion battery is widely applied to various industries, and the lithium ion battery is concerned by a plurality of researchers. However, in the use process of the lithium ion battery, the uncontrollable lithium dendrite grows from the metal lithium along with the reaction, and the lithium dendrite pierces the diaphragm to cause the short circuit of the battery or generate dead lithium, thereby causing the waste of lithium resources. In order to solve the problem, the current general method is to load metallic lithium in a material with a special structure to inhibit the growth of lithium dendrite, thereby relieving the problem of resource waste. However, the current commercial preparation method of the three-dimensional layered structure is complex, high in cost and unsatisfactory in effect.

Therefore, the preparation method of the three-dimensional layered boron-doped titanium carbide, which is simple to operate, can uniformly deposit the lithium metal and can inhibit the growth of lithium dendrites, is a technical problem which is urgently needed to be solved at present.

Disclosure of Invention

The invention aims to provide three-dimensional layered boron-doped titanium carbide and a preparation method and application thereof. The safety, the cycle performance and the coulombic efficiency of the lithium metal battery are greatly improved.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of three-dimensional layered boron-doped titanium carbide, which comprises the following steps:

1) mixing Ti₃AlC₂Reacting with LiF in HCl solution, washing the obtained product to be neutral, and drying to obtain Ti₃C₂Powder;

2) mixing Ti₃C₂Powder, water and H₃BO₃And carrying out mixed hydrothermal reaction to obtain the three-dimensional layered boron-doped titanium carbide.

Further, said Ti₃AlC₂Mass of LiF and HCl solutionThe volume ratio is 10-2000 mg: 10-3000 mg: 1-50 mL.

Further, the concentration of the HCl solution is 3-12 mol/L.

Further, in the step 1), the reaction temperature is 20-30 ℃, and the reaction time is 1-72 hours.

Further, in the step 1), the drying temperature is 40-120 ℃, and the drying time is 4-12 hours.

Further, said Ti₃C₂Powder, water and H₃BO₃The mass-to-volume ratio of (A) is 30-900 mg: 300-9000 mL: 10-800 mg.

Further, the temperature of the hydrothermal reaction is 20-400 ℃, and the time of the hydrothermal reaction is 2-72 hours.

Further, drying treatment is needed after the hydrothermal reaction, wherein the temperature of the drying treatment is 40-120 ℃, and the time of the drying treatment is 4-10 hours.

The invention provides three-dimensional layered boron-doped titanium carbide.

The invention provides application of three-dimensional layered boron-doped titanium carbide as a negative electrode material in a lithium ion battery.

The invention has the beneficial effects that:

the framework of the three-dimensional layered current collector obtained by doping titanium carbide with three-dimensional layered boron can be loaded with metal lithium, and boron ions doped on the three-dimensional layered boron-doped titanium carbide can induce the metal lithium to be uniformly deposited so as to achieve the purpose of uniformly depositing the metal lithium. Thus, the growth of lithium dendrites can be well inhibited, the cycle life of lithium is improved, and the coulombic efficiency is improved.

The invention innovatively uses boron ions as nucleation sites, and can regulate and control the uniformity of lithium in the electrodeposition process, so that the lithium-ion lithium electrodeposition process is suitable for electrochemical application. Furthermore, the uniformity and the deposition amount of the metal lithium deposition are controlled by regulating the current density and the deposition time, so that the electrochemical performance of the metal lithium deposition is improved.

The obtained three-dimensional layered current collector has a specific interlayer spacing, can contain a part of lithium metal, can prepare a lithium metal cathode with larger surface capacity, can relieve volume change in the process of embedding and releasing, inhibits the growth of lithium dendrites, and improves the coulombic efficiency. The obtained three-dimensional layered current collector is simple and easy to operate and is beneficial to large-scale production.

Drawings

FIG. 1 is a scanning electron micrograph of three-dimensional layered boron-doped titanium carbide prepared in example 1;

FIG. 2 shows that the three-dimensional layered boron-doped titanium carbide prepared in example 1 is loaded with 1mAhcm^-2Cross-sectional scanning electron micrographs of lithium;

FIG. 3 shows that the three-dimensional layered boron-doped titanium carbide prepared in example 1 is loaded with 2mAhcm^-2Cross-sectional scanning electron micrographs of lithium;

FIG. 4 shows that the three-dimensional layered boron-doped titanium carbide prepared in example 1 is loaded with 4mAhcm^-2Cross-sectional scanning electron micrographs of lithium;

FIG. 5 shows that the three-dimensional layered boron-doped titanium carbide prepared in example 1 is loaded with 1mAhcm^-2Planar scanning electron micrographs of lithium;

FIG. 6 shows that the three-dimensional layered boron-doped titanium carbide prepared in example 1 is loaded with 2mAhcm^-2Planar scanning electron micrographs of lithium;

FIG. 7 shows that the three-dimensional layered boron-doped titanium carbide prepared in example 1 is loaded with 4mAhcm^-2Planar scanning electron micrographs of lithium;

FIG. 8 is a graph of the deposition/precipitation efficiency of lithium from three-dimensional layered boron-doped titanium carbide and pure titanium carbide prepared in example 1;

FIG. 9 is a scanning electron micrograph of three-dimensional layered boron-doped titanium carbide prepared according to example 2;

fig. 10 is a scanning electron micrograph of the three-dimensional layered boron-doped titanium carbide prepared in example 3.

Detailed Description

The invention provides a preparation method of three-dimensional layered boron-doped titanium carbide, which comprises the following steps:

1) mixing Ti₃AlC₂Reacting with LiF in HCl solution, washing the obtained product to be neutral, and drying to obtain Ti₃C₂Powder;

2) mixing Ti₃C₂Powder, water and H₃BO₃And carrying out mixed hydrothermal reaction to obtain the three-dimensional layered boron-doped titanium carbide.

In the present invention, the Ti is₃AlC₂The mass-to-volume ratio of LiF to HCl solution is 10-2000 mg: 10-3000 mg: 1-50 mL, preferably 50-1800 mg: 100-2800 mg: 5-45 mL, more preferably 200-1500 mg: 200-2500 mg: 20-40 mL.

In the invention, the concentration of the HCl solution is 3-12 mol/L, preferably 5-10 mol/L, and more preferably 8 mol/L.

In the invention, in the step 1), the reaction temperature is 20-30 ℃, the reaction time is 1-72 hours, preferably the reaction temperature is 22-28 ℃, the reaction time is 5-65 hours, more preferably the reaction temperature is 25 ℃, and the reaction time is 10-50 hours.

In the invention, in the step 1), the drying temperature is 40-120 ℃, the drying time is 4-12 h, preferably the drying temperature is 50-100 ℃, the drying time is 5-10 h, more preferably 60-90 ℃, and the drying time is 6-9 h.

In the present invention, the Ti is₃C₂Powder, water and H₃BO₃The mass-to-volume ratio of (A) is 30-900 mg: 300-9000 mL: 10-800 mg, preferably 50-800 mg: 500-8000 mL: 50-700 mg, more preferably 100-700 mg: 1000-7000 mL: 100-600 mg.

In the present invention, Ti₃C₂The concentration of the dispersion obtained by mixing the powder with water is 0.001 to 0.2mg/mL, preferably 0.1 mg/mL.

In the invention, the temperature of the hydrothermal reaction is 20-400 ℃, the time of the hydrothermal reaction is 2-72 h, preferably the temperature of the hydrothermal reaction is 50-300 ℃, the time of the hydrothermal reaction is 5-70 h, more preferably the temperature of the hydrothermal reaction is 100-250 ℃, and the time of the hydrothermal reaction is 10-60 h.

In the invention, after the hydrothermal reaction, drying treatment is required, wherein the temperature of the drying treatment is 40-120 ℃, the time of the drying treatment is 4-10 h, preferably the temperature of the drying treatment is 50-110 ℃, the time of the drying treatment is 5-9 h, further preferably the temperature of the drying treatment is 60-100 ℃, and the time of the drying treatment is 6-8 h.

The invention provides three-dimensional layered boron-doped titanium carbide.

The invention provides application of three-dimensional layered boron-doped titanium carbide as a negative electrode material in a lithium ion battery, wherein a metal current collector is made of one or more of iron, cobalt, nickel, manganese and copper.

The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.

Example 1

Preparing three-dimensional layered boron-doped titanium carbide:

1500mgTi at room temperature₃AlC₂And 2000mg LiF was added to 25mL of 10mol/LHCl and reacted for 70 hours. And washing the semi-finished product with deionized water to be neutral. Furthermore, the powder was collected by centrifugation at 8000rpm for 20 minutes. Finally, the resulting product was dried in a vacuum oven at 100 ℃ for 10 hours. Mixing 800mgTi₃C₂The powder was uniformly dispersed in deionized water. Then, 500mgH₃BO₃Is added to Ti₃C₂And stirred for half an hour. The suspension was transferred to a teflon reaction furnace and heated at 380 ℃ for 60 hours, resulting in a grey-black precipitate. After centrifugation, the obtained product is dried in vacuum at 100 ℃ to obtain the three-dimensional layered boron-doped titanium carbide.

It can be clearly seen from the scanning electron micrograph of fig. 1 that boron is embedded in the surface of the layered titanium carbide of the three-dimensional layered boron-doped titanium carbide structure.

(II) assembling the battery: weighing 150mg of the three-dimensional layered boron-doped titanium carbide, adding PVDF (polyvinylidene fluoride) in a proper proportion as a binder, uniformly mixing, coating the mixture on a copper foil to form a positive plate, taking a lithium plate as a negative electrode, taking Celgard as a diaphragm and taking LiTFSI + DOL + DME + 1% LiNO as a diaphragm in a vacuum glove box₃And assembling the button cell as an electrolyte.

(III) preparing a metal lithium negative electrode taking three-dimensional layered boron doped titanium carbide as a current collector:

respectively carrying out electrolytic deposition on lithium by taking the prepared three-dimensional layered boron-doped titanium carbide as a cathode and a lithium sheet as an anode to obtain 1mAhcm of lithium^-2，2mAhcm^-2，4mAhcm^-2。

From the scanning electron micrograph of the cross section of FIG. 2, it can be seen that the three-dimensional layered boron-doped titanium carbide is loaded with 1mAhcm^-2The thickness of the lithium was 47.5 um. The cross section is uniform and has no dendrite.

From the scanning electron micrograph of the cross section of FIG. 3, it can be seen that the three-dimensional layered boron-doped titanium carbide is loaded with 2mAhcm^-2The thickness of the lithium is 80.9 um. The cross section is uniform and has no dendrite.

From the scanning electron micrograph of the cross section of FIG. 4, it can be seen that the three-dimensional layered boron-doped titanium carbide is loaded with 4mAhcm^-2The thickness of the lithium is 303 um. The cross section is uniform and has no dendrite.

From the scanning electron micrograph of FIG. 5, it can be seen that the three-dimensional layered boron-doped titanium carbide is loaded with 1mAhcm^-2The lithium surface is uniform and has no dendrites. Lithium is first deposited in the interlayer space of titanium carbide and the surface of titanium carbide is uniformly covered with lithium metal spheres taking boron ions as nucleation sites.

From the scanning electron micrograph of FIG. 6, it can be seen that the three-dimensional layered boron-doped titanium carbide is loaded with 2mAhcm^-2The lithium surface is uniform and has no dendrites. Three-dimensional layered boron-doped titanium carbide surface load of 2mAhcm^-2Lithium, the boron-doped titanium carbide material is completely covered by lithium.

From the scanning electron micrograph of FIG. 7, it can be seen that the three-dimensional layered boron-doped titanium carbide is loaded with 4mAhcm^-2The lithium surface is uniform and has no dendrites. Three-dimensional layered boron-doped titanium carbide surface load of 4mAhcm^-2Lithium, boron doped titanium carbide was completely covered with lithium and the deposited lithium was gradually increased. The fact that lithium is firstly deposited in the interlayer spacing of titanium carbide shows that the interlayer spacing limits the growth of lithium dendrites and improves the coulombic efficiency and the safety of the battery.

(IV) electrochemical test of lithium metal secondary battery:

using a charge-discharge instrument to carry out the process of the batteryConstant current charge and discharge test with cutoff capacity of 0.5mA hcm^-2The test temperature was 25 ℃.

FIG. 8 shows the lithium negative electrode at 0.5mAhcm^-2Charge and discharge curves at current density. The deposition/precipitation efficiency of lithium reaches about 99% after 20 cycles. The voltage remained stable for 70 cycles.

And (V) assembling a symmetrical battery by using the negative electrodes:

in this example, to test the safety and cycle life of the negative electrode, the 2mA hcm prepared as described above was used^-2Lithium is the positive and negative electrodes. And (3) assembling the full cell by using the ester electrolyte, and testing the electrochemical performance of the three-dimensional layered boron-doped titanium carbide current collector.

Example 2

1000mgTi at room temperature₃AlC₂And 1500mg of LiF were added to 20mL of 5mol/LHCl and reacted for 60 hours. And washing the semi-finished product with deionized water to be neutral. Furthermore, the powder was collected by centrifugation at 8000rpm for 20 minutes. Finally, the resulting product was dried in a vacuum oven at 100 ℃ for 10 hours. Mixing 800mgTi₃C₂The powder was uniformly dispersed in deionized water. Then, 1000mgH₃BO₃Is added to Ti₃C₂And stirred for half an hour. The suspension was transferred to a teflon reaction furnace and heated at 400 ℃ for 50 hours, resulting in a grey-black precipitate. After centrifugation, the obtained product is dried in vacuum at 100 ℃ to obtain the three-dimensional layered boron-doped titanium carbide.

Example 3

At room temperature, 800mgTi₃AlC₂And 1200mg LiF was added to 15mL of 12mol/LHCl and reacted for 50 hours. And washing the semi-finished product with deionized water to be neutral. Furthermore, the powder was collected by centrifugation at 8000rpm for 20 minutes. Finally, the resulting product was dried in a vacuum oven at 100 ℃ for 10 hours. Mixing 800mgTi₃C₂The powder was uniformly dispersed in deionized water. Then, 500mgH₃BO₃Is added to Ti₃C₂And stirred for half an hour. The suspension was transferred to a teflon reaction furnace and heated at 200 ℃ for 60 hours, resulting in a grey-black precipitate.After centrifugation, the obtained product is dried in vacuum at 100 ℃ to obtain the three-dimensional layered boron-doped titanium carbide.

Comparative example

1500mgTi at room temperature₃AlC₂And 2000mLLIF was added to 25mL of 10mol/LHCl and reacted for 70 hours. And washing the semi-finished product with deionized water to be neutral. Furthermore, the powder was collected by centrifugation at 8000rpm for 20 minutes. Finally, the resulting product was dried in a vacuum oven at 100 ℃ for 10 hours.

Assembling the battery: weighing 150mg of titanium carbide material, adding PVDF (polyvinylidene fluoride) as a binder in a proper proportion, uniformly mixing, coating the mixture on a copper foil to form a positive plate, taking a lithium plate as a negative electrode, taking Celgard as a diaphragm and taking LiTFSI + DOL + DME + 1% LiNO as a diaphragm in a vacuum glove box₃And assembling the button cell as an electrolyte.

As shown in fig. 8, although the number of cycles until 90% of titanium carbide is small, the coulombic efficiency is unstable and decreases rapidly.

The embodiments of the present invention can show that, when the three-dimensional layered boron-doped titanium carbide of the present invention is used for a metal negative electrode carrier, the growth of lithium dendrites can be effectively inhibited, thereby improving the coulombic efficiency and the cycle life.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.