Preparation method of fluorine-doped carbon material and application thereof

Abstract

The application relates to a preparation method and application of fluorine-doped carbon material, and relates to a preparation method and application of carbon material. The method comprises the following steps: S1, preparing a sodium fluoride solution; S2, adding perchloric acid drop by drop into the sodium fluoride solution to obtain a mixed solution; S3, adding carbon material into the mixed solution; and S4, carrying out hydrothermal reaction to obtain fluorine-doped carbon material. The preparation process of the fluorine-doped carbon material is optimized, the compactness and uniformity of a protective layer are realized, the corrosion resistance and cycle stability of a zinc negative electrode are remarkably improved, and important technical support is provided for large-scale application of water-based zinc ion batteries. The zinc negative electrode with the fluorine-doped carbon coating on the surface prepared by the application is used as a negative electrode of a water-based zinc ion battery. The fluorine-doped carbon material prepared by the application can effectively improve the corrosion resistance and cycle stability of the zinc negative electrode, and provides technical support for large-scale application of water-based zinc ion batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a carbon material and its application. BACKGROUND

[0002] With the increasing demand for energy and the promotion of sustainable development goals, the development and utilization of clean energy have become particularly important. Zinc-ion batteries, as a new type of aqueous energy storage device, have attracted widespread attention due to their low material cost, strong environmental friendliness, and excellent safety performance. However, there are significant technical bottlenecks in the practical application of zinc anodes, which severely limit their widespread application.

[0003] The main problems of zinc anode include the growth of zinc dendrites and the hydrogen evolution corrosion reaction. The formation of dendrites is caused by the uneven deposition of zinc ions on the surface of the negative electrode. These dendrites not only pierce the battery separator to cause short circuits, but also cause active material loss, thereby reducing the coulombic efficiency of the battery. In addition, the hydrogen evolution corrosion reaction of the zinc anode in the aqueous electrolyte consumes a large amount of electrolyte, while generating gas to cause battery swelling, thereby shortening the cycle life of the battery.

[0004] In view of the above problems, current researches mainly focus on electrolyte modification, separator design, and the construction of negative electrode protection layer. Among them, the construction of a protection layer on the surface of the zinc anode is considered to be the most direct and efficient solution. The material of such a protection layer needs to have high mechanical strength, chemical stability, and good zinc ion transmission capacity. Existing protection layer researches are mostly focused on inorganic materials and polymer materials, but the performance of a single material often cannot fully meet the actual demand. For example, although inorganic materials have excellent mechanical strength, they have poor ductility and are prone to cracking during long-term cycling; while the toughness of polymer materials is good, but their performance in inhibiting dendrites and corrosion resistance is limited. SUMMARY

[0005] To solve the above technical problems, the present application provides a preparation method of a fluorine-doped carbon material and its application.

[0006] The present application optimizes the preparation process of fluorine-doped carbon material, realizes the compactness and uniformity of the protection layer, significantly improves the corrosion resistance and cycle stability of the zinc anode, and provides important technical support for the large-scale application of aqueous zinc-ion batteries. The fluorine-doped carbon material prepared by the present application can effectively improve the corrosion resistance and cycle stability of the zinc anode, providing technical support for the large-scale application of aqueous zinc-ion batteries.

[0007] A preparation method of a fluorine-doped carbon material, which is completed according to the following steps:

[0008] I. Sodium fluoride is added to deionized water and magnetically stirred to obtain a sodium fluoride solution;

[0009] II. Under the condition of magnetic stirring, perchloric acid is added dropwise into the sodium fluoride solution to obtain a mixed solution;

[0010] III. Under the condition of magnetic stirring, the carbon material is added into the mixed solution, then magnetic stirring is carried out, and ultrasonic dispersion is carried out to obtain a dispersion liquid;

[0011] IV. The dispersion liquid is transferred into a reaction kettle, and hydrothermal reaction is carried out for a period of time; after the reaction is completed, a reaction product is obtained; the reaction product is washed and dried to obtain a fluorine-doped carbon material.

[0012] The present application has the following beneficial effects:

[0013] I. The present application optimizes the preparation process of the fluorine-doped carbon material, making it more efficient and suitable for large-scale application; it provides more reliable and low-cost technical support for aqueous zinc ion batteries; the zinc anode with a fluorine-doped carbon coating prepared by the present application has the advantages of long cycle life and good stability, and the coating preparation process is simple and has industrialization prospects;

[0014] II. By constructing a fluorine-doped carbon protective layer on the surface of the zinc anode, the present application effectively blocks the direct contact between the electrolyte and the zinc anode, inhibits the hydrogen evolution corrosion reaction, and simultaneously regulates the uniform deposition of zinc ions, significantly reducing the risk of zinc dendrite growth and improving the cycle stability of the battery;

[0015] III. The Zn / / Zn symmetric battery assembled using the modified zinc anode (zinc anode with a fluorine-doped carbon coating on the surface) can be stably cycled at a current density of 5mA / cm 2 for more than 4500h, far exceeding the life of the symmetric battery assembled using the unmodified zinc anode (original zinc anode).

[0016] The present application can obtain a fluorine-doped carbon material and a zinc anode with a fluorine-doped carbon coating on the surface, which can be used as a negative electrode for aqueous zinc ion batteries. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Scanning electron microscope image of the polypyrrole-derived carbon tube prepared in Example 1;

[0018] Figure 2 Transmission electron microscope image and corresponding fluorine element EDS energy spectrum distribution map of the fluorine-doped carbon material prepared in Example 1;

[0019] Figure 3 F1s high-resolution X-ray photoelectron spectroscopy of the fluorine-doped carbon material prepared in Example 1;

[0020] Figure 4F1s high resolution X-ray photoelectron spectroscopy of the fluorine-doped carbon material prepared for Example 2;

[0021] Figure 5 F1s high resolution X-ray photoelectron spectroscopy of the fluorine-doped carbon material prepared for Example 3;

[0022] Figure 6 Time-voltage curve of the symmetric battery assembled by using the zinc negative electrode with the fluorine-doped carbon coating prepared by using the application example 1 under the test condition of 5mA / cm 2 , 1mAh / cm 2 ;

[0023] Figure 7 Time-voltage curve of the symmetric battery assembled by using the zinc negative electrode modified by using the commercial carbon nanotube prepared by using the application example 2 under the test condition of 5mA / cm 2 , 1mAh / cm 2 . DETAILED DESCRIPTION

[0024] Detailed implementation one: the preparation method of the fluorine-doped carbon material in the embodiment, specifically is completed according to the following steps:

[0025] I. sodium fluoride is added to deionized water, and magnetic stirring is carried out, to obtain a sodium fluoride solution;

[0026] II. under the condition of magnetic stirring, perchloric acid is added dropwise into the sodium fluoride solution to obtain a mixed solution;

[0027] III. under the condition of magnetic stirring, carbon material is added into the mixed solution, then magnetic stirring is carried out, and ultrasonic dispersion is carried out, to obtain a dispersion liquid;

[0028] IV. the dispersion liquid is transferred into a reaction kettle, and hydrothermal reaction is carried out for a period of time, after the reaction is completed, a reaction product is obtained; the reaction product is washed and dried, to obtain the fluorine-doped carbon material.

[0029] Detailed implementation two: the difference between the embodiment and detailed implementation one is that the concentration of the sodium fluoride solution in step I is 100mmol / L-500mmol / L; the speed of the magnetic stirring in step I is 800r / min-1000r / min, and the time of the magnetic stirring is 30min-60min. The other steps are the same as detailed implementation one.

[0030] Specific embodiment three: the difference between this embodiment and one or two of the specific embodiments is that the concentration of perchloric acid in step two is 0.01 mol / L-0.47 mmol / L, the perchloric acid is added dropwise to the sodium fluoride solution in step two until the pH value of the mixed solution is 2-4, and the addition of perchloric acid is stopped; the speed of magnetic stirring in step two is 800 r / min-1000 r / min. The other steps are the same as those in specific embodiment one or two.

[0031] Specific embodiment four: the difference between this embodiment and one of the specific embodiments one to three is that the speed of magnetic stirring in step three is 800 r / min-1000 r / min, and the time of magnetic stirring is 60 min-90 min; the mass of carbon material to the volume of mixed solution in step three is (40 mg-60 mg):(80 mL-120 mL); the time of ultrasonic dispersion in step three is 60 min-90 min, and the power of ultrasonic dispersion is 160 W-180 W. The other steps are the same as those in specific embodiments one to three.

[0032] Specific embodiment five: the difference between this embodiment and one of the specific embodiments one to four is that the carbon material in step three is one or several of polypyrrole derived carbon tube, carbon nanotube, porous carbon, graphene, graphite, activated carbon, carbon black, carbon fiber, carbon quantum dot or carbon-based composite material. The other steps are the same as those in specific embodiments one to four.

[0033] Specific embodiment six: the difference between this embodiment and one of the specific embodiments one to five is that the preparation method of polypyrrole derived carbon tube is as follows:

[0034] ①, methyl orange is added to deionized water, and then stirred under water bath heating conditions until methyl orange is completely dissolved to obtain a methyl orange solution;

[0035] The concentration of the methyl orange solution in step ① is 15 mmol / L-30 mmol / L; the temperature of water bath heating in step one is 60℃-80℃.

[0036] ②, pyrrole monomer and p-toluenesulfonic acid are added to the methyl orange solution, and magnetic stirring is performed to obtain a mixed solution;

[0037] The volume ratio of pyrrole monomer to methyl orange solution in step ② is (300 μL-400 μL):(80 mL-120 mL);

[0038] The mass ratio of p-toluenesulfonic acid to methyl orange solution in step ② is (120 mg-150 mg):(80 mL-120 mL);

[0039] The magnetic stirring speed in step 2 is 800 r / min-1000 r / min, and the magnetic stirring time is 60 min-90 min;

[0040] 3. FeCl3 is added into deionized water and stirred magnetically to obtain a FeCl3 solution; the FeCl3 solution is stirred magnetically under ice-bath condition for a period of time, and then added dropwise into the mixed solution, and stirred continuously under ice-water bath condition for a period of time to obtain solid reactant I; the solid reactant I is washed and dried to obtain solid reactant II;

[0041] The concentration of the FeCl3 solution in step 3 is 40 mmol / L-60 mmol / L;

[0042] The magnetic stirring speed in step 3 is 500 r / min-1000 r / min, and the magnetic stirring time is 10 min-30 min;

[0043] The FeCl3 solution is stirred magnetically under ice-bath condition for 1 h-2 h in step 3;

[0044] The volume ratio of the FeCl3 solution to the methyl orange solution in the mixed solution in step 3 is (15 mL-25 mL):(80 mL-120 mL);

[0045] The continuous stirring speed under ice-water bath condition in step 3 is 700 r / min-900 r / min, and the continuous stirring time is 24 h-36 h;

[0046] The solid reactant I is washed with deionized water until the washing solution is colorless in step 3;

[0047] The drying temperature is 70℃-90℃, and the drying time is 8 h-10 h;

[0048] 4. The solid reactant II is transferred into a tube furnace, heated to a calcination temperature under an inert gas atmosphere, calcined at the calcination temperature for a period of time, and then ground into particles to obtain polypyrrole-derived carbon tubes;

[0049] The inert gas in step 4 is nitrogen, argon, helium or a mixture of the above;

[0050] The heating rate in step 4 is 2℃ / min-10℃ / min;

[0051] The calcination temperature in step 4 is 700℃-900℃, and the calcination time is 60 min-100 min. The other steps are the same as steps 1-5 in the specific embodiment.

[0052] Specific embodiment seven: the difference between this embodiment and one of the specific embodiments one to six is that the temperature of the hydrothermal reaction in step four is 150℃-180℃, the time of the hydrothermal reaction is 15h-24h; deionized water is used to clean the reaction product in step four until the reaction product is neutral; the temperature of the drying in step four is 60℃-80℃, the time of the drying is 10h-16h. The other steps are the same as specific embodiments one to six.

[0053] Specific embodiment eight: this embodiment is a fluorine-doped carbon material for modifying zinc negative electrode.

[0054] Specific embodiment nine: the difference between this embodiment and one of the specific embodiments one to eight is that a fluorine-doped carbon material is used to modify the zinc negative electrode, which is completed according to the following steps:

[0055] I. Disperse the fluorine-doped carbon material and the binder in the solvent to obtain a dispersion liquid;

[0056] The solvent in step one is one or a mixture of several of N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile, dichloromethane and ethanol;

[0057] The binder in step one is one or a mixture of several of polyvinylidene fluoride, polyacrylic acid, sodium carboxymethyl cellulose, styrene-butadiene rubber, chitosan and polyurethane;

[0058] The mass ratio of the fluorine-doped carbon material to the binder in step one is (8-9):(1-2);

[0059] The mass fraction of the fluorine-doped carbon material in the dispersion liquid in step one is 20%-60%;

[0060] II. Coating the dispersion liquid to the surface of the zinc negative electrode, drying to obtain a zinc negative electrode with a fluorine-doped carbon coating on the surface;

[0061] The drying temperature in step two is 60℃-80℃;

[0062] The thickness of the fluorine-doped carbon coating on the surface of the zinc negative electrode in step two is 5μm-30μm. The other steps are the same as specific embodiments one to eight.

[0063] Specific embodiment ten: the difference between this embodiment and one of the specific embodiments one to nine is that the zinc negative electrode with a fluorine-doped carbon coating on the surface in step two is used as the negative electrode of the aqueous zinc ion battery. The other steps are the same as specific embodiments one to nine.

[0064] The beneficial effects of the present application are verified by the following examples:

[0065] Embodiment 1: A preparation method of a poly-pyrrole derivative carbon tube modified zinc negative electrode, specifically completed according to the following steps:

[0066] I. Preparation of carbon material

[0067] ①, methyl orange is added to deionized water, and then stirred at 80°C water bath heating condition until the methyl orange is completely dissolved to obtain a methyl orange solution;

[0068] The concentration of the methyl orange solution in step ① is 15 mmol / L;

[0069] ②, 350 μL of pyrrole monomer and 140 mg of p-toluenesulfonic acid are added to 100 mL of methyl orange solution, and then magnetically stirred at a speed of 800 r / min for 60 min to obtain a mixed solution;

[0070] ③, ferric chloride is added to deionized water, and then magnetically stirred at a speed of 1000 r / min for 30 min to obtain a ferric chloride solution; the ferric chloride solution is magnetically stirred at 0°C ice bath condition for 1 h, the speed of magnetic stirring is 800 r / min, then 20 mL of ferric chloride solution is added to the mixed solution obtained in step two, and the magnetic stirring is continued at a speed of 800 r / min and ice water bath condition for 24 h to obtain solid reactant I; solid reactant I is washed with deionized water for 3 times, and then dried at 70°C for 10 h to obtain solid reactant II;

[0071] The concentration of the ferric chloride solution in step ③ is 50 mmol / L;

[0072] ④, solid reactant II is transferred to a tube furnace, heated to 800°C under nitrogen atmosphere, calcined at 800°C for 80 min, and then ground into particles to obtain poly-pyrrole derivative carbon tube, which is carbon material;

[0073] The rate of heating in step ④ is 5°C / min;

[0074] II. Sodium fluoride is added to 100 mL of deionized water, and then magnetically stirred at a speed of 1000 r / min for 30 min to obtain a sodium fluoride solution;

[0075] The concentration of the sodium fluoride solution in step II is 100 mmol / L;

[0076] III. Perchloric acid is added dropwise to the sodium fluoride solution under the condition of stirring at a speed of 1000 r / min until the pH value of the mixed solution is 3 to obtain a mixed solution;

[0077] The concentration of perchloric acid in step III is 0.06 mmol / L;

[0078] 4. Under magnetic stirring conditions, 50 mg of the carbon material prepared in step 1 (4) was added to the mixed solution, followed by magnetic stirring for 60 min, and then ultrasonic dispersion for 60 min to obtain a dispersion;

[0079] 5. The dispersion was transferred to a reactor and subjected to a hydrothermal reaction at 160°C for 16 hours. After the reaction was completed, a reaction product was obtained. The reaction product was washed with deionized water until it was neutral, and then dried at 60°C for 12 hours to obtain a fluorine-doped carbon material.

[0080] Figure 1 This is a scanning electron micrograph of the polypyrrole-derived carbon nanotubes prepared in Example 1;

[0081] Figure 2 The transmission electron microscopy image of the fluorine-doped carbon material prepared in Example 1 and the corresponding EDS energy spectrum distribution diagram of the fluorine element;

[0082] from Figure 2 It can be seen that the morphology and structure of the fluorine-doped carbon material prepared in Example 1 are not destroyed compared with that before doping (polypyrrole-derived carbon tubes), and obvious uniform distribution of fluorine elements can be observed.

[0083] Figure 3 This is the F1s high-resolution X-ray photoelectron spectrum of the fluorine-doped carbon material prepared in Example 1;

[0084] from Figure 3 It can be seen from the figure that the fluorine-doped carbon material prepared in Example 1 can detect obvious fluorine element signals, which once again confirms the successful doping of fluorine element.

[0085] Example 2: This example differs from Example 1 in that the sodium fluoride solution in step 2 is 10 mmol / L. Other steps and parameters are the same as those in Example 1.

[0086] Figure 4 This is the F1s high-resolution X-ray photoelectron spectrum of the fluorine-doped carbon material prepared in Example 2;

[0087] from Figure 4 It can be seen from the figure that no obvious fluorine element signal can be detected in the fluorine-doped carbon material prepared in Example 2, which proves that effective fluorine doping cannot be performed when the concentration of the sodium fluoride solution is too low.

[0088] Example 3: This example differs from Example 1 in that the sodium fluoride solution in step 2 is 1000 mmol / L. Other steps and parameters are the same as those in Example 1.

[0089] Figure 5 This is the F1s high-resolution X-ray photoelectron spectrum of the fluorine-doped carbon material prepared in Example 3;

[0090] It can be seen from Figure 5 that the morphology of the fluorine-doped carbon material prepared in Example 3 is destroyed, which proves that a too high concentration of sodium fluoride solution can increase the damage to the morphology of the carbon material.

[0091] Application Example 1: The fluorine-doped carbon material prepared in Example 1 was used to modify the zinc negative electrode, which was completed according to the following steps:

[0092] I. 20 mg of the fluorine-doped carbon material prepared in Example 1 and polyvinylidene fluoride were dispersed in 100 μL of N-methylpyrrolidone to obtain a dispersion liquid;

[0093] The mass ratio of the fluorine-doped carbon material to polyvinylidene fluoride in step I was 9:1;

[0094] II. The zinc negative electrode with a thickness of 100 μm was polished to be bright using sandpaper to remove the oxide layer, the coating thickness of the coater was adjusted to 150 μm, and then the dispersion liquid was coated on the surface of the polished zinc negative electrode, which was dried at 80°C for 12 h to obtain a zinc negative electrode with a fluorine-doped carbon coating on the surface.

[0095] Figure 6 The symmetric battery assembled with the zinc negative electrode with a fluorine-doped carbon coating on the surface prepared in Application Example 1 was tested under the conditions of 5 mA / cm 2 , 1 mAh / cm 2 , and the time-voltage curve was obtained.

[0096] It can be seen from Figure 6 that compared with the symmetric battery composed of untreated pure zinc sheets, the cycle life of the symmetric battery composed of the fluorine-doped carbon material modified zinc negative electrode is obviously improved, and the stable cycle is more than 4500 h, and the polarization voltage does not appear obvious fluctuation in the whole cycle process, which shows extremely excellent cycle stability, and powerfully proves the advantages of the fluorine-doped carbon material modified zinc negative electrode.

[0097] Application Example 2: The commercial carbon nanotubes were used to modify the zinc negative electrode, which was completed according to the following steps:

[0098] I. 20 mg of commercial carbon nanotubes (prepared by chemical vapor deposition) sold by Mclane and polyvinylidene fluoride were dispersed in 100 μL of N-methylpyrrolidone to obtain a dispersion liquid;

[0099] The mass ratio of the commercial carbon nanotubes to polyvinylidene fluoride in step I was 9:1;

[0100] II. The zinc negative electrode with a thickness of 100 pm was polished to a shine using sandpaper to remove the oxide layer. The applicator was adjusted to a thickness of 150 pm, and the dispersion was applied to the surface of the polished zinc negative electrode. The sample was dried at 80 °C for 12 h to obtain a commercial carbon nanotube-modified zinc negative electrode.

[0101] Figure 7 A symmetric battery was assembled using the commercial carbon nanotube-modified zinc negative electrode prepared in Example 2. The symmetric battery was cycled at 5 mA / cm 2 , 1 mAh / cm 2 under the test conditions, and the time-voltage curve is shown in FIG. 6.

[0102] As can be seen from Figure 7 , the symmetric battery assembled using the zinc negative electrode directly modified with carbon nanotubes short-circuits after only about 200 hours of cycling, demonstrating that it cannot effectively improve the cycle life of the zinc negative electrode.

Claims

1. A method for preparing a fluorine-doped carbon material, characterized in that The preparation method is specifically completed according to the following steps:

1. Add sodium fluoride to deionized water and stir magnetically to obtain a sodium fluoride solution; The concentration of the sodium fluoride solution described in step 1 is 100 mmol / L to 500 mmol / L; 2. Under magnetic stirring, adding perchloric acid dropwise to the sodium fluoride solution to obtain a mixed solution; 3. Adding polypyrrole-derived carbon tubes to the mixed solution under magnetic stirring, followed by magnetic stirring and ultrasonic dispersion to obtain a dispersion; The preparation method of the polypyrrole-derived carbon nanotubes described in step 3 is specifically completed by the following steps: ①. Add methyl orange to deionized water, and then stir in a water bath until the methyl orange is completely dissolved to obtain a methyl orange solution; The concentration of the methyl orange solution in step ① is 15 mmol / L to 30 mmol / L; the temperature of the water bath heating in step 1 is 60° C. to 80° C.; ②, adding pyrrole monomer and p-toluenesulfonic acid to the methyl orange solution, stirring magnetically to obtain a mixed solution; The volume ratio of the pyrrole monomer to the methyl orange solution in step ② is (300 μL~400 μL):(80 mL~120 mL); The volume ratio of the mass of p-toluenesulfonic acid described in step ② to the methyl orange solution is (120 mg ~ 150 mg): (80 mL ~ 120 mL); The speed of the magnetic stirring in step ② is 800 rpm to 1000 rpm, and the time of the magnetic stirring is 60 min to 90 min. ③. Add ferric chloride to deionized water and stir magnetically to obtain a ferric chloride solution; The ferric chloride solution was magnetically stirred in an ice bath for a period of time, and then added dropwise to the mixed solution, and stirred continuously in an ice-water bath for a period of time to obtain a solid reactant I; The solid reactant I is washed and dried to obtain a solid reactant II; The concentration of the ferric chloride solution described in step ③ is 40mmol / L~60mmol / L; The speed of the magnetic stirring in step ③ is 500 rpm to 1000 rpm, and the time of the magnetic stirring is 10 min to 30 min; In step ③, the ferric chloride solution is magnetically stirred in an ice bath for 1 h to 2 h; The volume ratio of the ferric chloride solution described in step ③ to the methyl orange solution in the mixed solution is (15mL~25mL):(80mL~120mL); In step ③, the stirring speed is 700 rpm to 900 rpm under ice-water bath conditions, and the stirring time is 24 h to 36 h; In step ③, the solid reactant I is washed with deionized water until the washing solution is colorless; The drying temperature is 70°C to 90°C, and the drying time is 8h to 10h; ④, transferring the solid reactant II to a tube furnace, raising the temperature to a calcination temperature under an inert atmosphere, calcining at the calcination temperature for a period of time, and grinding into particles after calcination to obtain polypyrrole-derived carbon tubes; The inert atmosphere in step ④ is nitrogen, argon, helium or a mixture of the above; The heating rate in step ④ is 2°C / min~10°C / min; The calcination temperature in step ④ is 700°C to 900°C, and the calcination time is 60min to 100min; 4. The dispersion is transferred to a reactor and subjected to hydrothermal reaction for a period of time. After the reaction is completed, a reaction product is obtained; the reaction product is washed and dried to obtain a fluorine-doped carbon material.

2. The method for preparing a fluorine-doped carbon material according to claim 1, characterized in that The speed of the magnetic stirring in step 1 is 800 r / min~1000 r / min, and the time of the magnetic stirring is 30 min~60 min.

3. The method for preparing a fluorine-doped carbon material according to claim 1, characterized in that The concentration of the perchloric acid in step 2 is 0.01 mol / L~0.47 mmol / L. In step 2, the perchloric acid is added dropwise to the sodium fluoride solution until the pH value of the mixed solution reaches 2~4, and the addition of perchloric acid is stopped. The speed of the magnetic stirring in step 2 is 800r / min~1000r / min.

4. The method for preparing a fluorine-doped carbon material according to claim 1, characterized in that The magnetic stirring speed in step 3 is 800 r / min~1000 r / min, and the magnetic stirring time is 60 min~90 min; the mass ratio of the polypyrrole-derived carbon tubes in step 3 to the volume ratio of the mixed solution is (40 mg~60 mg):(80 mL~120 mL); the ultrasonic dispersion time in step 3 is 60 min~90 min, and the ultrasonic dispersion power is 160 W~180 W.

5. The method for preparing a fluorine-doped carbon material according to claim 1, characterized in that The temperature of the hydrothermal reaction described in step 4 is 150°C~180°C, and the time of the hydrothermal reaction is 15h~24h; in step 4, the reaction product is washed with deionized water until the reaction product is neutral; the drying temperature described in step 4 is 60°C~80°C, and the drying time is 10h~16h.

6. An application of fluorine-doped carbon material, characterized in that A fluorine-doped carbon material prepared by the preparation method according to any one of claims 1 to 5 is used to modify a zinc negative electrode.

7. The use of a fluorine-doped carbon material according to claim 6, characterized in that A fluorine-doped carbon material is used to modify a zinc negative electrode, which is specifically completed by the following steps:

1. dispersing the fluorine-doped carbon material and the binder in a solvent to obtain a dispersion; The solvent in step 1 is one or a mixture of N-methylpyrrolidone, dimethyl sulfoxide, acetonitrile, dichloromethane and ethanol; The binder in step 1 is one or a mixture of polyvinylidene fluoride, polyacrylic acid, sodium carboxymethyl cellulose, styrene-butadiene rubber, chitosan and polyurethane; The mass ratio of the fluorine-doped carbon material to the binder in step 1 is (8-9):(1-2); Step 1: The mass fraction of the fluorine-doped carbon material in the dispersion is 20% to 60%; 2. coating the dispersion onto the surface of the zinc negative electrode and drying it to obtain a zinc negative electrode having a fluorine-doped carbon coating on the surface; The drying temperature in step 2 is 60°C to 80°C; In step 2, the thickness of the fluorine-doped carbon coating on the surface of the zinc negative electrode is 5 μm to 30 μm.

8. The use of a fluorine-doped carbon material according to claim 7, characterized in that The zinc negative electrode with a fluorine-doped carbon coating on its surface as described in step 2 is used as the negative electrode of an aqueous zinc ion battery.

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