1. High purity phase multilayer V₂The preparation method of the material C is characterized by comprising the following steps:

firstly, mixing 0.6-1 g V₂Placing the AlC powder into 40-60 mL of HF aqueous solution with the mass concentration of 30% -50%, and stirring and reacting at room temperature for 240-288 hours to obtain a reaction solution;

repeatedly centrifuging the reaction liquid obtained in the step one at 5000-12000 r/min by using a centrifugal machine, adding deionized water for cleaning, repeating for many times, centrifuging and cleaning until the pH value of the supernatant is 5-7, and collecting solid-phase precipitate;

thirdly, drying the solid-phase precipitate obtained in the second step to obtain a high-purity-phase multilayer V₂And C, material.

2. The high purity phase multilayer V of claim 1₂The preparation method of the material C is characterized in that the V in the step one₂The grain size of AlC powder is 200 meshes.

3. The high purity phase multilayer V of claim 1₂The preparation method of the C material is characterized in that V in the step one₂The volume ratio of the mass of the AlC powder to the HF aqueous solution is 1 g: 52-58 mL.

4. The high purity phase multilayer V of claim 1₂The preparation method of the material C is characterized in that 0.8g V is added in the step one₂Placing the AlC powder into 40-50 mL of HF aqueous solution with the mass concentration of 30% -50%.

5. The high purity phase multilayer V of claim 1₂The preparation method of the material C is characterized in that in the step one, the material C is stirred and reacts for 250-270 hours at room temperature.

6. The high purity phase multilayer V of claim 1₂The preparation method of the material C is characterized in that a centrifuge is adopted in the second step to repeatedly centrifuge at 7000 r/min-9000 r/min.

7. The high purity phase multilayer V of claim 1₂And C, a preparation method of the material C, which is characterized in that the time of each centrifugation in the step two is 5 minutes.

8. The high purity phase multilayer V of claim 1₂The preparation method of the material C is characterized in that the step two is repeated for 6-8 times.

9. The high purity phase multilayer V of claim 1₂The preparation method of the material C is characterized in that the solid-phase precipitate in the step three is subjected to vacuum drying treatment, the vacuum drying temperature is 60 ℃, and the drying time is 12 hours.

10. High purity phase multilayer V₂Use of C materials, characterised in that high-purity phases are laminated V₂The C material is used as a negative electrode material and applied to the lithium ion battery.

Background

In 2004, the graphite of Novoselov et al successfully exfoliated flakes consisting of only one layer of carbon atoms, and after the unique electronic properties of graphene were discovered, great attention was paid to two-dimensional materials. 2011, Yury Gogotsi and Barsum collaboratively discover a novel two-dimensional material Ti₃C₂Since then, the attention of a large number of MXenes materials has been paid. Among the MXenes materials, they have been most widely studied in the field of energy storage due to their good capacitive properties and electrical conductivity and their lower Ti-Al bond, which makes them easier to prepare. V₂C is a member of MXenes materials, which also possesses surface hydrophilicity, metal conductivity and excellent electrochemical properties, but is comparable to high-purity phase Ti₃C₂Preparation of high purity phase multilayer V₂The preparation of C is very difficult. To date, no one has corroded high purity multi-layer V₂C. V was first assigned by Michael Naguib and Yury Gogotsi et al in 2013₂The AlC powder is immersed in HF solution to synthesize multilayer V₂And C, the reaction time is 90h, and the temperature is room temperature. However V prepared by this method₂C does not crystallize well by XRD and it is reported that there is about 15 wt% V₂AlC does not participate in the reaction, which also means that the purity of the AlC is not high, and the AlC can reach 210mAh/g after circulation is stable under the current density of 1C through testing the electrical performance of the electrode, and the purity of the AlC is not high, so that the multilayer V cannot be completely reflected₂And C is excellent in performance. In 2015, Zhou Patrio et al studied HF vs. V under different temperature and time conditions₂The result of the corrosion behavior of AlC shows that V is at 50-65 DEG C₂Corresponding V can not be prepared by soaking and stirring AlC powder in 49 percent HF solution for 120h₂C two-dimensional crystal; after soaking for 40h at 70 ℃, a small amount of Al gradually appears₂O₃And V₂O₅And a small number of two-dimensional transparent sheet structures were observed, predicted to be V₂C two-dimensional crystal, and analysis of the result shows that V cannot be successfully prepared₂C, but the experimental exploration shows the relationship between HF concentration and etching temperature and time to V₂The influence of the C preparation process is particularly important. In 2020, ZhangYajuan et al general V₂The AlC powder is immersed into HF solution, the reaction temperature is fixed to 35 ℃, the reaction time is strictly controlled to 120h, and the generation of a multilayer structure can be observed through SEM images of the AlC powder, however, the multilayer V prepared by the method₂C, in XRD pattern, V₂Characteristic peak of C and V₂The characteristic peak of AlC is very weak, indicating that the purity is not high, by mixing the multilayer V₂C, the electrical property of the electrode is tested, and the result shows that the capacity after the circulation stabilization is 241mAh/g under the current density of 0.1A/g, because the purity is not high and V is not completely embodied₂And electrical properties of the C electrode. V₂C has the advantages of stable structure, good conductivity, excellent lithium storage capacity and capability of being compounded with a plurality of materials.

Disclosure of Invention

The object of the invention is to solve the problem of the prior art of etching a multilayer V with HF solutions₂The C purity is low, the synthesis method is complicated, and the high-purity phase multilayer V which has high purity and simple synthesis method can be prepared₂And C, a method for preparing the material.

The invention relates to a high-purity phase multilayer V₂The preparation method of the material C is realized according to the following steps:

firstly, mixing 0.6-1 g V₂Placing the AlC powder into 40-60 mL of HF aqueous solution with the mass concentration of 30% -50%, and stirring and reacting at room temperature for 240-288 hours to obtain a reaction solution;

repeatedly centrifuging the reaction liquid obtained in the step one at 5000-12000 r/min by using a centrifugal machine, adding deionized water for cleaning, repeating for many times, centrifuging and cleaning until the pH value of the supernatant is 5-7, and collecting solid-phase precipitate;

thirdly, drying the solid-phase precipitate obtained in the second step to obtain a high-purity-phase multilayer V₂And C, material.

The invention relates to a high-purity phase multilayer V₂Application of C material as negative electrode material in lithium ion batteryIn (1).

The invention adopts HF solution to etch high-purity multi-layer V for the first time₂And during preparation of the material C, the dosage of the HF aqueous solution is increased to 40-60 ml, the chemical reaction time is increased to 240-288 h, and the reaction temperature is room temperature. Moderate increases in reaction time and acid levels allow the chemical reaction to proceed more actively and completely. Laminating high purity phases V₂When C is used as the cathode of the lithium ion battery, the multilayer V is tested₂C, the specific capacity of the negative electrode material is kept at 333.8mAh/g after circulating for 65 circles under the current density of 0.1A/g, and is kept at 109.1mAh/g after circulating for 650 circles under the current density of 2A/g, so that the negative electrode material has a series of advantages of high specific capacity, stable circulation, long service life and the like. Compared with the prior art, the invention has reasonable process, simple and convenient operation and excellent performance, and is a lithium ion battery cathode material with application prospect.

Drawings

FIG. 1 shows the high-purity phase multilayer V obtained in example I₂XRD pattern of material C;

FIG. 2 shows the high-purity phase multilayer V obtained in example one₂EDX plot of material C;

FIG. 3 shows the high-purity phase multilayer V obtained in example one₂SEM image of material C;

FIG. 4 shows the high-purity phase multilayer V obtained in example one₂C material under the current density of 0.1A/g charge-discharge cycle test chart, wherein 1-cycle efficiency, 2-specific discharge capacity, 3-specific charge capacity;

FIG. 5 shows the high-purity multi-layer V obtained in example one₂C, a charge-discharge cycle test chart of the material under different current densities, wherein 1 is discharge specific capacity, and 2 is charge specific capacity;

FIG. 6 shows the high-purity multi-layer V obtained in example one₂C, a charge-discharge cycle test chart of the material under the current density of 2A/g, wherein an upper curve represents cycle efficiency, and a lower curve represents discharge specific capacity;

FIG. 7 shows the high-purity multi-layer V obtained in example one₂CV curve test chart of C material, wherein 1 represents 5.0mVs^-1And 2 represents 2.0mVs^-1And 3 represents 1.0mVs^-1And 4 represents 0.5mVs^-15 th generationTABLE 0.1mVs^-1；

FIG. 8 shows the high purity phase multilayer V obtained in example one₂EIS map of material C.

Detailed Description

The first embodiment is as follows: the high purity phase multilayer V of the present embodiment₂The preparation method of the material C is implemented according to the following steps:

firstly, mixing 0.6-1 g V₂Placing the AlC powder into 40-60 mL of HF aqueous solution with the mass concentration of 30% -50%, and stirring and reacting at room temperature for 240-288 hours to obtain a reaction solution;

repeatedly centrifuging the reaction solution obtained in the step one at 6000-12000 r/min by using a centrifugal machine, adding deionized water for cleaning, repeating for many times, centrifuging and cleaning until the pH value of the supernatant is 5-7, and collecting solid-phase precipitate;

thirdly, drying the solid-phase precipitate obtained in the second step to obtain a high-purity-phase multilayer V₂And C, material.

The high purity phase multilayer V of the present embodiment₂The C material is a high-purity phase multilayer V formed by etching with HF solution₂C。

The second embodiment is as follows: the difference between the first embodiment and the second embodiment is that V is described in the first step₂The grain size of AlC powder is 200 meshes.

The third concrete implementation mode: the difference between this embodiment and the first or second embodiment is that V is the first step₂The volume ratio of the mass of the AlC powder to the HF aqueous solution is 1 g: 52-58 mL.

The fourth concrete implementation mode: this embodiment differs from one of the first to third embodiments in that 0.8gV is added in the first step₂Placing the AlC powder into 40-50 mL of HF aqueous solution with the mass concentration of 30% -50%.

The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is that in the first step, the reaction is performed at room temperature for 250 to 270 hours with stirring.

The sixth specific implementation mode: the present embodiment is different from the first to fifth embodiments in that the repeated centrifugation is performed at 7000r/min to 9000r/min by using a centrifuge in the second step.

The seventh embodiment: this embodiment differs from one of the first to sixth embodiments in that the time for each centrifugation in step two is 5 minutes.

The specific implementation mode is eight: the present embodiment is different from the first to seventh embodiments in that the second step is repeated 6 to 8 times.

The specific implementation method nine: the difference between this embodiment and the first to eighth embodiments is that the solid phase precipitate is vacuum dried in step three, the vacuum drying temperature is 60 ℃, and the drying time is 12 h.

The detailed implementation mode is ten: this embodiment combines high purity phases into a multilayer V₂The C material is used as a negative electrode material and applied to the lithium ion battery.

The first embodiment is as follows: this example high purity phase multilayer V₂The preparation method of the material C is implemented according to the following steps:

firstly, 0.8g V₂Placing AlC powder (200 meshes) into 45mL of HF aqueous solution with the mass concentration of 40%, and stirring and reacting for 264 hours at room temperature to obtain reaction liquid;

repeatedly centrifuging the reaction liquid obtained in the step one at 8000r/min by adopting a centrifuge, adding deionized water for cleaning, wherein the centrifuging time is 5 minutes each time, separating supernate from precipitate in each cleaning process, adding deionized water into the precipitate, shaking up, centrifuging again for multiple times, centrifugally cleaning until the pH value of the supernate is 6, and collecting solid-phase precipitate;

thirdly, carrying out vacuum drying treatment on the solid-phase precipitate obtained in the second step, wherein the vacuum drying temperature is 60 ℃, and the drying time is 12 hours, so as to obtain the high-purity-phase multilayer V₂And C, material.

The high purity phase multilayer V obtained in this example₂XRD of C material is shown in figure 1, from which Nb can be seen₂The diffraction peak of the AlC powder at 41.3 degrees basically disappears completely after corrosion, and the 002 peak is advanced to 9.1 degrees from the original 13.5 degrees. To this end, it can be shown that V was successfully synthesized₂And C, material.

FIG. 2 is V₂EDX spectrum of C with V, C, O, F and Al atomic ratio of 2.03:106:0.79:0.06, it can be seen that the Al content is very small, indicating that the high-purity-phase multilayer V was successfully synthesized₂And C, material.

FIG. 3 is a high purity phase multilayer V₂SEM photograph of material C, illustrating the structure of the multilayer.

FIGS. 4 to 8 are high purity phase multilayers V₂C electrochemical performance test chart of material, a little V₂Grinding the C material into powder as an active substance, mixing the active substance with acetylene black and polyvinylidene fluoride into slurry according to the mass ratio of 7:1.5:1.5, coating the slurry on copper foil to prepare an electrode sheet, drying the electrode sheet, pressing the electrode sheet into a 13mm electrode sheet by using a hand-press punching machine after drying, then preparing the electrode sheet into a button type lithium ion battery in a glove box, and then testing the electrochemical performance of the button type lithium ion battery, wherein as can be seen from figure 4, the current density of 0.1A/g circulates for 65 circles, the specific capacity is kept at 333.8mAh/g (reported by Michael Naguib, Yury Gogotsi and the like, and under the current density of 1C, the circulation stability can reach 210mAh/g, reported by ZhangYajuan and the like, and under the current density of 0.1A/g, V is used as an active substance₂The capacity after C circulation stabilization is 241mAh/g), and the coulombic efficiency is close to 100%. Fig. 5 is a charge-discharge cycle test plot at different current densities showing good rate performance. As can be seen from FIG. 6, the high purity phase multilayer V₂The C negative electrode material circulates 650 circles under the current density of 2A/g, the specific capacity is kept at 109.1mAh/g, and the coulombic efficiency is close to 100%. FIG. 7 is the drawing V₂The CV curve of the C material illustrates the capacitive behavior at different sweep rates. FIG. 8 is the drawing V₂The EIS map of the material C shows that the material has smaller charge transfer resistance and good particle diffusion capacity. Taken together, it is shown that the high purity phase multilayer V₂The C material is a promising lithium ion battery cathode material.