Fluorine-doped graphdiyne material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of new energy batteries, and particularly relates to a fluorine-doped graphdiyne material and a preparation method and application thereof. The preparation method of the fluorine-doped graphdiyne material comprises the following steps: in a solvent system, mixing graphdiyne and a solid fluorine source, and drying to obtain a composite precursor; under the protective atmosphere, the composite precursor is annealed, so that the fluorine source is decomposed to release hydrogen fluoride and fluorine free radicals, the hydrogen fluoride or the fluorine free radicals are combined with carbon sites on graphdiyne through nucleophilic substitution, C-F bonds are formed, and the fluorine-doped graphdiyne material is obtained; the mass ratio of graphdiyne to the solid fluorine source is 30: (1-4). The fluorine-doped graphdiyne has the advantages that the defects are increased, the disorder is reduced, and the lithium storage capacity of the graphdiyne is improved, so that the long-term cycle performance and the high-rate performance are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy batteries, and specifically relates to a fluorine-doped graphyne material and a preparation method and application thereof. Background Art

[0002] GDY is a two-dimensional carbon allotrope composed of sp and sp 2 Composed of hybrid carbon atoms, graphyne combines the electrical conductivity of graphene with the porosity of carbon-rich materials. Its unique wide interlayer spacing, high specific surface area, ordered three-dimensional pore structure, and excellent charge transport properties give it significant potential for applications in electronics, energy storage, photoelectric conversion, and catalysis.

[0003] In the field of energy storage, especially in lithium-ion batteries, the capacity of traditional graphyne-based anode materials decays to 65% of the initial value after 50 charge and discharge cycles, making it difficult to meet the long-term stable high capacity requirements of high power density applications.

[0004] To increase the energy density of graphyne-based lithium-ion batteries, existing technologies primarily modify graphyne through methods such as alkaline crystallization and light element doping. Fluorine doping is an effective approach for improving graphyne's electrochemical performance. Fluorine atoms, due to their strong electronegativity, can modulate the electronic structure, enhance the stability of the electrode-electrolyte interface, and widen the interlayer spacing, accelerating ion diffusion.

[0005] Existing fluorine doping methods mostly use in-situ doping technology, for example, Reference 1: He J, Wang N, Yang Z, et al. Fluoride graphdiyne as a free-standing electrode displaying ultra-stable and extraordinary high Li storage performance[J]. Energy&EnvironmentalScience, 2018, 11(10): 2893-2903. Reference 1 used high temperature and high pressure fluorination to prepare 3,5-trifluoro-2,4,6-tribromobenzene and 1,3,5-(trimethylsilyl)ethyl-2,4,6-trifluorobenzene, and then synthesized fluorinated graphene by Glaser coupling reaction on copper foil.

[0006] However, most in-situ doping technologies need to be implemented under high temperature, high pressure or plasma conditions, with high equipment requirements and complicated operation steps. In addition, in-situ doping usually reacts violently and easily leads to excessive fluorination. Summary of the Invention

[0007] In order to solve the technical problem that the synthesis process of in-situ doping is complex and difficult to control, the present invention provides a fluorine-doped graphyne material and a preparation method and application thereof.

[0008] The first object of the present invention is to provide a method for preparing a fluorine-doped graphene material, comprising the following steps: In a solvent system, graphyne and a solid fluorine source are mixed and dried to obtain a mixed powder; the mixed powder is annealed under a protective atmosphere to decompose the fluorine source to release hydrogen fluoride and fluorine free radicals. The hydrogen fluoride or fluorine free radicals combine with the carbon sites on the graphyne through nucleophilic substitution to form C-F bonds, thereby obtaining a fluorine-doped graphyne material.

[0009] It should be noted that during the annealing process, the solid fluorine source decomposes to release hydrogen fluoride or fluorine radicals, and the sp hybridized acetylenic bonds or sp 2 The hybrid benzene ring provides active sites for fluorine atoms, and hydrogen fluoride or fluorine radicals bind to carbon sites on the surface of graphyne through nucleophilic substitution to form CF bonds, thereby achieving fluorine doping.

[0010] Preferably, the solid fluorine source is polyvinylidene fluoride or polyvinyl fluoride.

[0011] Preferably, the degree of polymerization of polyvinylidene fluoride is 1300-5000, and the degree of polymerization of polyvinyl fluoride is 1300-5000.

[0012] Preferably, the mass ratio of graphyne to solid fluorine source is 30:1-4.

[0013] Preferably, the mixing time is 4 to 8 hours and the temperature is room temperature.

[0014] Preferably, the annealing temperature is 400° C. to 600° C. and the annealing time is 0.5 h to 5 h. A shorter annealing time allows fluorine atoms to be doped only on the surface, but a longer annealing time may result in fluorine aggregation or structural damage.

[0015] Preferably, the solvent is N-methylpyrrolidone or N,N-dimethylformamide.

[0016] Preferably, the preparation method of graphyne is as follows: Hexaethynylbenzene and tetrabutylammonium fluoride are mixed in a solvent system and then rotary evaporated to obtain a mixed powder. Copper powder, pyridine solution and the mixed powder are placed at 110° C. in a protective atmosphere to react in the dark to obtain graphyne powder.

[0017] Preferably, the temperature of mixing hexaethynylbenzene and tetrabutylammonium fluoride is -10°C to -2°C.

[0018] Preferably, the solvent used to prepare graphyne is tetrahydrofuran.

[0019] Preferably, the light-proof reaction time is 48 hours.

[0020] The second object of the present invention is to provide a fluorine-doped graphyne material prepared by the above preparation method.

[0021] The third object of the present invention is to provide the use of the above-mentioned fluorine-doped graphyne material for preparing anode materials for metal ion batteries.

[0022] Preferably, the metal ion battery is a lithium ion battery, a sodium ion battery, a zinc ion battery, or a potassium ion battery. Preferably, the preparation method of the negative electrode material of the metal ion battery is as follows: Fluorine-doped graphyne material, activated carbon and polyvinylidene fluoride are mixed to obtain an active slurry; wherein the mass ratio of the fluorine-doped graphyne material, activated carbon and polyvinylidene fluoride is 8:1:1.

[0023] The active slurry is coated on a current collector and dried to form an active material layer on the current collector to obtain a negative electrode sheet.

[0024] The negative electrode sheet, separator material, electrolyte and positive electrode sheet are assembled in sequence to produce a metal ion battery.

[0025] Preferably, the current collector is copper foil.

[0026] Preferably, the drying temperature is 80°C and the drying time is 12 hours.

[0027] Preferably, the positive electrode plate is a lithium plate or a sodium plate.

[0028] Preferably, the electrolyte is 1M LiPF6.

[0029] Compared with the prior art, the present invention has the following technical effects: 1. In the present invention, graphyne and a solid fluorine source are fluorinated by sintering to decompose the solid fluorine source, releasing hydrogen fluoride or fluorine free radicals, and the sp hybridized acetylenic bonds or sp 2 The hybrid benzene ring provides an active site for fluorine atoms, and hydrogen fluoride or fluorine radicals combine with carbon sites on the surface of graphyne through nucleophilic substitution to form C-F bonds, thereby realizing the doping of fluorine atoms into graphyne. At the same time, by regulating the amount of solid fluorine source added, the doping amount of fluorine atoms into graphyne is controlled, thus solving the technical problems of complex and difficult-to-control in-situ doping synthesis process in the existing technology.

[0030] 2. The defects of fluorine-doped graphyne in the present invention are increased and the disorder is reduced, which improves the lithium storage capacity of graphyne, thereby improving the long-term cycle performance and high-rate performance; and the fluorine-doped graphyne is easy to react with the electrolyte to form more stable fluoride, further reducing the possibility of structural collapse of the negative electrode material after long cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the SEM image of the fluorine-doped graphyne material prepared in Example 1.

[0032] Figure 2 Raman spectra of the fluorine-doped graphyne materials prepared in Comparative Example 1 and Example 1.

[0033] Figure 3 This is the XPS graph of the fluorine-doped graphyne material prepared in Example 1.

[0034] Figure 4 The charge and discharge curves of the lithium-ion battery prepared in Example 1 are shown.

[0035] Figure 5 The charge and discharge curves of the sodium ion battery prepared in Example 1 are shown. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments.

[0037] In the description of the present invention, unless otherwise specified, all reagents used are commercially available and all methods used are conventional techniques in the art.

[0038] Example 1 A method for preparing a fluorine-doped graphene material comprises the following steps: At -10°C, 30 mg of hexaethynylbenzene and 30 mL of tetrahydrofuran were mixed, and 2 mL of tetrabutylammonium fluoride solution was added. The mixture was stirred until the mixture turned purple. The mixture was subjected to rotary evaporation to obtain a precursor powder. The evaporation temperature was 60°C and the rotation speed was 50 r / min.

[0039] 100 mg of copper powder and 30 mL of tetrapyridine solution were mixed in a three-necked flask, and then the precursor powder was added. The mixture was heated at 110° C. for 48 h in an argon environment and protected from light to obtain graphyne powder.

[0040] 30 mg of graphyne powder and 2 mg of polyvinylidene fluoride were dissolved in 30 mL of N-methylpyrrolidone, stirred for 6 h, washed and dried to obtain a mixed powder.

[0041] The mixed powder was heated to 500° C. at a heating rate of 3° C. / min in an argon environment and annealed for 2 h to obtain a fluorine-doped graphyne material.

[0042] Example 2 A method for preparing a fluorine-doped graphene material comprises the following steps: At -8°C, 30 mg of hexaethynylbenzene and 30 mL of tetrahydrofuran were mixed, and 2 mL of tetrabutylammonium fluoride solution was added. The mixture was stirred until the mixture turned purple. The mixture was rotary evaporated to obtain a precursor powder. The evaporation temperature was 60°C and the rotation speed was 50 r / min.

[0043] 100 mg of copper powder and 30 mL of tetrapyridine solution were mixed in a three-necked flask, and then the precursor powder was added. The mixture was heated at 110° C. for 48 h in an argon environment and protected from light to obtain graphyne powder.

[0044] 30 mg of graphyne powder and 1 mg of polyvinylidene fluoride were dissolved in 30 mL of N-methylpyrrolidone, stirred for 4 h, washed and dried to obtain a mixed powder.

[0045] The mixed powder was heated to 500° C. at a heating rate of 3° C. / min in an argon environment and annealed for 2 h to obtain a fluorine-doped graphyne material.

[0046] The difference from Example 1 is: The amount of polyvinylidene fluoride used is 1 mg.

[0047] Example 3 A method for preparing a fluorine-doped graphene material comprises the following steps: At -10°C, 30 mg of hexaethynylbenzene and 30 mL of tetrahydrofuran were mixed, and 2 mL of tetrabutylammonium fluoride solution was added. The mixture was stirred until the mixture turned purple. The mixture was subjected to rotary evaporation to obtain a precursor powder. The evaporation temperature was 60°C and the rotation speed was 50 r / min.

[0048] 100 mg of copper powder and 30 mL of tetrapyridine solution were mixed in a three-necked flask, and then the precursor powder was added. The mixture was heated at 110° C. for 48 h in an argon environment and protected from light to obtain graphyne powder.

[0049] 30 mg of graphyne powder and 4 mg of polyvinylidene fluoride were dissolved in 30 mL of N-methylpyrrolidone, stirred for 8 h, washed and dried to obtain a mixed powder.

[0050] The mixed powder was heated to 500° C. at a heating rate of 3° C. / min in an argon environment and annealed for 2 h to obtain a fluorine-doped graphyne material.

[0051] The difference from Example 1 is: The amount of polyvinylidene fluoride used is 4 mg.

[0052] Example 4 A method for preparing a fluorine-doped graphene material comprises the following steps: At -10°C, 30 mg of hexaethynylbenzene and 30 mL of tetrahydrofuran were mixed, and 2 mL of tetrabutylammonium fluoride solution was added. The mixture was stirred until the mixture turned purple. The mixture was subjected to rotary evaporation to obtain a precursor powder. The evaporation temperature was 60°C and the rotation speed was 50 r / min.

[0053] 100 mg of copper powder and 30 mL of tetrapyridine solution were mixed in a three-necked flask, and then the precursor powder was added. The mixture was heated at 110° C. for 48 h in an argon environment and protected from light to obtain graphyne powder.

[0054] 30 mg of graphyne powder and 2 mg of polyvinylidene fluoride were dissolved in 30 mL of N-methylpyrrolidone, stirred for 6 h, washed and dried to obtain a mixed powder.

[0055] The mixed powder was heated to 600°C at a heating rate of 3°C / min in an argon environment and annealed for 2 hours to obtain a fluorine-doped graphyne material.

[0056] The difference from Example 1 is: The annealing temperature is 600°C.

[0057] Example 5 A method for preparing a fluorine-doped graphene material comprises the following steps: At -10°C, 30 mg of hexaethynylbenzene and 30 mL of tetrahydrofuran were mixed, and 2 mL of tetrabutylammonium fluoride solution was added. The mixture was stirred until the mixture turned purple. The mixture was subjected to rotary evaporation to obtain a precursor powder. The evaporation temperature was 60°C and the rotation speed was 50 r / min.

[0058] 100 mg of copper powder and 30 mL of tetrapyridine solution were mixed in a three-necked flask, and then the precursor powder was added. The mixture was heated at 110° C. for 48 h in an argon environment and protected from light to obtain graphyne powder.

[0059] 30 mg of graphyne powder and 2 mg of polyvinylidene fluoride were dissolved in 30 mL of N-methylpyrrolidone, stirred for 6 h, washed and dried to obtain a mixed powder.

[0060] The mixed powder was heated to 500° C. at a heating rate of 5° C. / min in an argon environment and annealed for 2 h to obtain a fluorine-doped graphyne material.

[0061] The difference from Example 1 is: The heating rate is 5°C / min.

[0062] Example 6 A method for preparing a fluorine-doped graphene material comprises the following steps: At -10°C, 30 mg of hexaethynylbenzene and 30 mL of tetrahydrofuran were mixed, and 2 mL of tetrabutylammonium fluoride solution was added. The mixture was stirred until the mixture turned purple. The mixture was subjected to rotary evaporation to obtain a precursor powder. The evaporation temperature was 60°C and the rotation speed was 50 r / min.

[0063] 100 mg of copper powder and 30 mL of tetrapyridine solution were mixed in a three-necked flask, and then the precursor powder was added. The mixture was heated at 110° C. for 48 h in an argon environment and protected from light to obtain graphyne powder.

[0064] 30 mg of graphyne powder and 2 mg of polyvinylidene fluoride were dissolved in 30 mL of N-methylpyrrolidone, stirred for 6 h, washed and dried to obtain a mixed powder.

[0065] The mixed powder was heated to 500° C. at a heating rate of 3° C. / min in an argon environment and annealed for 5 hours to obtain a fluorine-doped graphyne material.

[0066] The difference from Example 1 is: The insulation time is 5h.

[0067] Comparative Example 1 A method for preparing a graphyne material comprises the following steps: At -10°C, 30 mg of hexaethynylbenzene and 30 mL of tetrahydrofuran were mixed, and 2 mL of tetrabutylammonium fluoride solution was added. The mixture was stirred until the mixture turned purple. The mixture was subjected to rotary evaporation to obtain a precursor powder. The evaporation temperature was 60°C and the rotation speed was 50 r / min.

[0068] 100 mg of copper powder and 30 mL of tetrapyridine solution were mixed in a three-necked flask, and then the precursor powder was added. The mixture was heated at 110° C. for 48 h in an argon environment and protected from light to obtain a graphyne material.

[0069] The difference from Example 1 is: No polyvinylidene fluoride is added.

[0070] Comparative Example 2 A method for preparing a fluorine-doped graphene material comprises the following steps: 30 mg of hexaethynylbenzene and 10 mL of xenon difluoride were placed in a polytetrafluoroethylene liner filled with argon, and then the polytetrafluoroethylene liner was placed in a Teflon high-pressure reactor. The mixture was heated at 180°C for 12 hours and then cooled naturally to obtain 1,3,5-tris(trimethylsilyl)ethynyl-2,4,6-trifluorobenzene.

[0071] At -10°C, 30 mg of 1,3,5-tris(trimethylsilyl)ethynyl-2,4,6-trifluorobenzene and 30 mL of tetrahydrofuran were mixed, and 2 mL of tetrabutylammonium fluoride solution was added. The mixture was stirred until the mixed solution turned purple. The mixed solution was rotary evaporated to obtain a precursor powder. The evaporation temperature was 60°C and the rotation speed was 50 r / min.

[0072] 100 mg of copper powder and 30 mL of tetrapyridine solution were mixed in a three-necked flask, and then the precursor powder was added. The mixture was heated at 110° C. for 48 h in an argon environment and protected from light to obtain a fluorine-doped graphyne material.

[0073] Application Example 1 A method for preparing a lithium ion battery comprises the following steps: The fluorine-doped graphyne material prepared in Example 1, activated carbon and polyvinylidene fluoride were added to a mortar in a mass ratio of 8:1:1, and ground and mixed until viscous to obtain an active slurry.

[0074] The active slurry was coated on a copper foil and dried at 80° C. for 12 h to form an active material layer on the current collector to obtain a negative electrode sheet.

[0075] In a glove box where the oxygen and water content are both less than 0.1 ppm, the negative electrode sheet, diaphragm material, LiPF6 electrolyte, lithium sheet as positive electrode sheet and CR2032 battery shell are assembled in sequence to produce a lithium-ion battery.

[0076] Application Example 2 A method for preparing a lithium ion battery comprises the following steps: The fluorine-doped graphyne material prepared in Example 2, activated carbon and polyvinylidene fluoride were added to a mortar in a mass ratio of 8:1:1, and ground and mixed until viscous to obtain an active slurry.

[0077] The active slurry was coated on a copper foil and dried at 80° C. for 12 h to form an active material layer on the current collector to obtain a negative electrode sheet.

[0078] In a glove box where the oxygen and water content are both less than 0.1 ppm, the negative electrode sheet, diaphragm material, LiPF6 electrolyte, lithium sheet as positive electrode sheet and CR2032 battery shell are assembled in sequence to produce a lithium-ion battery.

[0079] Application Example 3 A method for preparing a lithium ion battery comprises the following steps: The fluorine-doped graphyne material prepared in Example 3, activated carbon and polyvinylidene fluoride were added to a mortar at a mass ratio of 8:1:1, and ground and mixed until viscous to obtain an active slurry.

[0080] The active slurry was coated on a copper foil and dried at 80° C. for 12 h to form an active material layer on the current collector to obtain a negative electrode sheet.

[0081] In a glove box where the oxygen and water content are both less than 0.1 ppm, the negative electrode sheet, diaphragm material, LiPF6 electrolyte, lithium sheet as positive electrode sheet and CR2032 battery shell are assembled in sequence to produce a lithium-ion battery.

[0082] Application Example 4 A method for preparing a lithium ion battery comprises the following steps: The fluorine-doped graphyne material prepared in Example 4, activated carbon and polyvinylidene fluoride were added into a mortar at a mass ratio of 8:1:1, and ground and mixed until viscous to obtain an active slurry.

[0083] The active slurry was coated on a copper foil and dried at 80° C. for 12 h to form an active material layer on the current collector to obtain a negative electrode sheet.

[0084] In a glove box where the oxygen and water content are both less than 0.1 ppm, the negative electrode sheet, diaphragm material, LiPF6 electrolyte, lithium sheet as positive electrode sheet and CR2032 battery shell are assembled in sequence to produce a lithium-ion battery.

[0085] Application Example 5 A method for preparing a lithium ion battery comprises the following steps: The fluorine-doped graphyne material prepared in Example 5, activated carbon and polyvinylidene fluoride were added to a mortar at a mass ratio of 8:1:1, and ground and mixed until viscous to obtain an active slurry.

[0086] The active slurry was coated on a copper foil and dried at 80° C. for 12 h to form an active material layer on the current collector to obtain a negative electrode sheet.

[0087] In a glove box where the oxygen and water content are both less than 0.1 ppm, the negative electrode sheet, diaphragm material, LiPF6 electrolyte, lithium sheet as positive electrode sheet and CR2032 battery shell are assembled in sequence to produce a lithium-ion battery.

[0088] Application Example 6 A method for preparing a lithium ion battery comprises the following steps: The fluorine-doped graphyne material prepared in Example 6, activated carbon and polyvinylidene fluoride were added to a mortar at a mass ratio of 8:1:1, and ground and mixed until viscous to obtain an active slurry.

[0089] The active slurry was coated on a copper foil and dried at 80° C. for 12 h to form an active material layer on the current collector to obtain a negative electrode sheet.

[0090] In a glove box where the oxygen and water content are both less than 0.1 ppm, the negative electrode sheet, diaphragm material, LiPF6 electrolyte, lithium sheet as positive electrode sheet and CR2032 battery shell are assembled in sequence to produce a lithium-ion battery.

[0091] Application Example 7 A method for preparing a sodium ion battery comprises the following steps: The fluorine-doped graphyne material prepared in Example 1, activated carbon and polyvinylidene fluoride were added to a mortar in a mass ratio of 8:1:1, and ground and mixed until viscous to obtain an active slurry.

[0092] The active slurry was coated on a copper foil and dried at 80° C. for 12 h to form an active material layer on the current collector to obtain a negative electrode sheet.

[0093] In a glove box with oxygen and water content below 0.1 ppm, the negative electrode sheet, diaphragm material, LiPF6 electrolyte, sodium sheet as positive electrode sheet and CR2032 battery shell were assembled in sequence to produce a sodium ion battery.

[0094] Comparative Application Example 1 A method for preparing a lithium ion battery comprises the following steps: The fluorine-doped graphyne material prepared in Comparative Example 1, activated carbon and polyvinylidene fluoride were added into a mortar at a mass ratio of 8:1:1, and ground and mixed until viscous to obtain an active slurry.

[0095] The active slurry was coated on a copper foil and dried at 80° C. for 12 h to form an active material layer on the current collector to obtain a negative electrode sheet.

[0096] In a glove box where the oxygen and water content are both less than 0.1 ppm, the negative electrode sheet, diaphragm material, LiPF6 electrolyte, lithium sheet as positive electrode sheet and CR2032 battery shell are assembled in sequence to produce a lithium-ion battery.

[0097] Application Comparative Example 2 A method for preparing a lithium ion battery comprises the following steps: The fluorine-doped graphyne material prepared in Comparative Example 2, activated carbon and polyvinylidene fluoride were added into a mortar at a mass ratio of 8:1:1, and ground and mixed until viscous to obtain an active slurry.

[0098] The active slurry was coated on a copper foil and dried at 80° C. for 12 h to form an active material layer on the current collector to obtain a negative electrode sheet.

[0099] In a glove box where the oxygen and water content are both less than 0.1 ppm, the negative electrode sheet, diaphragm material, LiPF6 electrolyte, lithium sheet as positive electrode sheet and CR2032 battery shell are assembled in sequence to produce a lithium-ion battery.

[0100] Experimental test.

[0101] 1. SEM test.

[0102] like Figure 1 As shown, the fluorine-doped graphyne material prepared in Example 1 maintains the original continuous network structure of graphyne.

[0103] 2. Raman test.

[0104] Usually, the intensity ratio of D peak to G peak (I D / I G ) can be used to characterize the disorder or defects of fluorine-doped graphyne materials. Figure 2 As shown, the fluorine-doped graphene material I prepared in Example 1 D / I G The value is 0.99; the I of the Graphdiyne material prepared in Comparative Example 1 D / I G The value is 0.70; compared with the graphyne material prepared in Comparative Example 1, the I of the fluorine-doped graphyne material prepared in the embodiment of the present invention is D / I G The larger the value, the higher the disorder.

[0105] 3. XPS test.

[0106] like Figure 3 As shown, the full XPS spectrum of fluorine-doped graphyne shows that C1s, O1s and F1s peaks appear at 284.8 eV, 532.0 eV and 688.0 eV, respectively, indicating that F atoms are successfully doped.

[0107] Table 1 Elemental composition and element content of fluorine-doped graphyne materials prepared in Examples 1 to 3 3. Electrochemical performance test.

[0108] The present invention uses a CHI760E electrochemical workstation produced by Shanghai Chenhua Instrument Co., Ltd. to perform constant current charge and discharge tests on the lithium ion batteries prepared in Application Examples 1 to Application Examples 6 and Application Comparative Examples 1 to Application Comparative Examples 2, respectively. The discharge specific capacity is calculated according to the following formula: ; in, C is the specific capacitance, Iis the discharge current in mA, Δt is the discharge time in h, and m is the mass of the active material in g.

[0109] like Figure 4 As shown, the discharge platform of the charge-discharge curve of the lithium-ion battery prepared in Example 1 is near 0.7V.

[0110] like Figure 5 As shown, the discharge platform of the charge-discharge curve of the sodium ion battery prepared in Example 7 is near 1.1V.

[0111] Table 2 Electrical performance data of lithium-ion batteries prepared in Application Examples 1 to 6 and Application Comparative Examples 1 to 2 As shown in Table 2, as the amount of polyvinylidene fluoride added increases, the discharge specific capacity of the lithium-ion battery prepared using fluorine-doped gydne material at different current densities first increases and then decreases. When the amount of polyvinylidene fluoride added is 2 mg, the lithium-ion battery prepared using fluorine-doped gydne material has the best discharge specific capacity at different current densities, and the capacity retention rate reaches 72.8% after 500 cycles. Compared with the lithium-ion battery prepared using fluorine-doped gydne material, the lithium-ion battery prepared using undoped fluorine-doped gydne material has a significantly lower discharge specific capacity at different current densities, and the capacity retention rate after 500 cycles drops to 43.6%. Compared with the fluorine-free gypsum material, the fluorine-doped gypsum material obtained by in-situ doping has an improved discharge specific capacity at different current densities; compared with the fluorine-doped gypsum material prepared by solid-phase sintering of gypsum and a solid fluorine source in Application Examples 1 to 3, the fluorine-doped gypsum material obtained by in-situ doping has a significantly reduced discharge specific capacity at different current densities, and the capacity retention rate after 500 cycles is 55.8%.

[0112] This shows that the defects of fluorine-doped graphyne in the embodiment of the present invention are increased and the disorder is reduced, which improves the lithium storage capacity of graphyne, thereby improving the long-term cycle performance and high-rate performance; and the fluorine-doped graphyne is easy to react with the electrolyte to form more stable fluoride, further reducing the possibility of structural collapse of the negative electrode material after long cycles.

[0113] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, the present invention describes preferred embodiments to avoid redundancy. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts, and such changes and modifications fall within the scope of the present invention.

[0114] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. If these modifications and variations of the present invention fall within the scope of the equivalent technology of the present invention, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a fluorine-doped graphene material, characterized in that: The following steps are involved: In a solvent system, graphyne and a solid fluorine source are mixed and dried to obtain a mixed powder; The mixed powder is annealed under a protective atmosphere to decompose the fluorine source to release hydrogen fluoride and fluorine free radicals. The hydrogen fluoride and fluorine free radicals combine with the carbon sites on the graphyne through nucleophilic substitution to form C-F bonds, thereby obtaining a fluorine-doped graphyne material. The mass ratio of graphyne to the solid fluorine source is 30:1-4.

2. The method for preparing fluorine-doped graphyne material according to claim 1, characterized in that: The solid fluorine source is polyvinylidene fluoride or polyvinyl fluoride.

3. The method for preparing fluorine-doped graphyne material according to claim 2, characterized in that: The degree of polymerization of polyvinylidene fluoride is 1300 to 5000, and the degree of polymerization of polyvinyl fluoride is 1300 to 5000.

4. The method for preparing fluorine-doped graphyne material according to claim 1, characterized in that: The annealing temperature is 400°C to 600°C.

5. The method for preparing fluorine-doped graphyne material according to claim 1, characterized in that: The mixing time is 4h to 8h, and the temperature is room temperature.

6. The method for preparing fluorine-doped graphyne material according to claim 1, characterized in that: The solvent is N-methylpyrrolidone or N,N-dimethylformamide.

7. A fluorine-doped graphyne material, characterized in that: The fluorine-doped graphene material is prepared by the preparation method of the fluorine-doped graphene material according to any one of claims 1 to 6.

8. Use of the fluorine-doped graphyne material according to claim 7 for preparing anode materials for metal ion batteries.

9. The use of the fluorine-doped graphyne material according to claim 8 for preparing anode materials for metal ion batteries, characterized in that: Metal ion batteries are lithium ion batteries, sodium ion batteries, zinc ion batteries or potassium ion batteries.

Images