Hydrofluorine atom doped graphdiyne material and preparation method thereof

Abstract

The invention discloses a hydrogen-fluorine atom doped graphdiyne material and a preparation method thereof, and relates to the technical field of carbon materials. According to the method, halogenated aromatic hydrocarbon and an alkynyl compound are taken as raw materials, a palladium catalyst and a copper catalyst are taken as a catalytic system, and an acetylenic bond of the alkynyl compound and the halogenated aromatic hydrocarbon are subjected to a Sonogashira coupling reaction to obtain the hydrogen-fluorine-doped graphite alkynyl material. The graphdiyne material provided by the invention has a large pore diameter, multiple active sites and high thermal stability and chemical stability, so that the hydrofluorine-doped graphdiyne material has excellent electrochemical energy storage property, shows reversible capacity of 1155mAh g <-1 > under 0.05 Ag <-1 > when being used as a negative electrode of a lithium ion battery, and can be used as a negative electrode of the lithium ion battery. And the density is almost 3 times that of a commercial graphite negative electrode material (300-350mAh g <-1 >). The application of the graphdiyne material in the field of electrochemical energy storage is obviously promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon materials, and in particular to a hydrogen-fluorine-doped graphyne material, a preparation method thereof, and lithium-ion battery applications. Background Art

[0002] Graphdiyne is composed of sp hybridized carbon atoms on the ethynyl unit and sp hybridized carbon atoms on the aromatic ring. 2 A new type of carbon material composed of hybrid carbon atoms, which forms a layered structure through van der Waals forces and π-π interactions. Therefore, graphyne has high π binding, adjustable electronic properties, a two-dimensional planar structure and a uniformly distributed pore structure, showing unique photoelectrochemical and energy storage properties, and has great application potential in energy, catalysis and other fields.

[0003] For example, the development of graphyne (GDY) as anode material for lithium-ion batteries has attracted increasing interest, but its electrochemical performance is limited by its lack of sufficient active sites and instability. Based on various studies of GDY as a lithium-ion battery electrode, two reasonable approaches remain to be considered to improve its lithium storage capacity. On the one hand, the larger pore size in the molecular structure facilitates ion diffusion in the bulk material. On the other hand, GDY can be doped with heteroatoms to increase lithium storage sites. The lower atomic density of hydrogen atoms facilitates higher capacity, allowing lithium to bind near hydrogen atoms. Due to the electronegativity difference between carbon and fluorine, fluorinated compounds exhibit high thermal and chemical stability. The lipophilicity of fluorinated aromatic hydrocarbons may lead to good wettability in organic electrolytes. In addition, C-F bonds can effectively enhance the mechanical properties of solid electrolyte membranes constructed at the electrode-electrolyte interface. Therefore, hydrogen-fluorine co-doping can effectively enhance the electrochemical activity of GDY.

[0004] Based on the above analysis, the present invention synthesized a large-pore hydrogen-fluorine heteroatom co-doped graphyne material for lithium-ion battery anode applications. The larger pore size within the molecular structure facilitates ion diffusion within the bulk material. Furthermore, hydrogen-fluorine co-doped graphyne further increases lithium storage sites and exhibits high thermal and chemical stability, effectively enhancing the electrochemical activity of graphyne. Summary of the Invention

[0005] The present invention aims to overcome the insufficient energy storage performance of prior art graphyne materials by providing a hydrogen-fluorine-doped graphyne material, its preparation method, its application, and a lithium-ion battery. The present invention utilizes a wide variety of low-cost halogenated aromatic hydrocarbons and produces fewer side reactions during polymerization, facilitating the development and utilization of diverse and high-quality graphyne materials while reducing the production cost of graphyne-based materials.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] The present invention uses halogenated aromatic hydrocarbons containing bromine and fluorine substitutions and alkynylbenzene compounds as starting materials, uses a palladium catalyst / copper catalyst as a composite catalytic system, and performs a Sonogashira cross-coupling reaction in a polar solvent and protective gas adjusted to an alkaline environment. During the reaction, the bromine group of the halogenated aromatic hydrocarbon is in situ removed through the acetylenic bond of the alkynylbenzene compound, and the bromine group is Sonogashira coupled with the halogenated aromatic hydrocarbon to obtain a graphene alkynyl material; the molar ratio of bromine to alkynyl is 1:1.5-1.5:1;

[0008] The reaction pathway of one type of substance is as follows:

[0009]

[0010] Preferably, the alkynylbenzene compound contains at least two ethynyl groups and is selected from hexaethynylbenzene, 1,3,5-triethynylbenzene or 1,4-diethynylbenzene.

[0011] More preferably, the halogenated aromatic hydrocarbon containing bromine and fluorine substitutions, wherein the bromine substitution includes at least two bromine substitutions, is selected from 1,4-dibromo-2,3,5,6-tetrafluorobenzene, 1,4-dibromo-2,3-difluorobenzene or 1,4-dibromo-2-fluorobenzene.

[0012] The polar solvent is selected from N,N-dimethylformamide, tetrahydrofuran, and toluene. These solvents can ensure efficient Sonogashira coupling reaction between monomers.

[0013] Preferably, the alkalinity is regulated by adding a base to the solvent to control the pH of the solvent to be 8 to 13; the base is selected from triethylamine, diisopropylamine, pyridine, potassium carbonate or sodium carbonate.

[0014] Preferably, the protective gas is selected from at least one of nitrogen, helium and argon.

[0015] Preferably, the palladium catalyst is selected from Pd(PPh3)4, Pd(PPh3)2Cl2 or Pd(dppf)Cl2.

[0016] Preferably, the copper catalyst is a monovalent copper catalyst selected from CuCl, CuBr, CuI or a Cu(I) complex dissolved from the surface of a copper sheet;

[0017] Preferably, the molar ratio of the palladium catalyst to the copper catalyst is 1:1 to 10:1, preferably 6:1;

[0018] Preferably, the Sonogashira cross-coupling reaction temperature is 60-120° C., and the reaction time is 24 h to 5 days, preferably 80° C. for 24 hours.

[0019] More preferably, a method for preparing graphene monoacetylene using halogenated aromatic hydrocarbons and alkynyl compounds as starting materials is as follows: 1,4-dibromo-2,3,5,6-tetrafluorobenzene is weighed and dissolved in N,N-dimethylformamide solution, triethylamine is added, argon is introduced for 15 minutes, and then Pd(PPh3)4, CuI, and 1,3,5-triethynylbenzene are added in sequence. The system is sealed and stirred at 80°C for 24 hours. After the reaction is completed, the black precipitate is filtered and washed three times with hydrochloric acid, distilled water, anhydrous ethanol, and dichloromethane in sequence, and then dried to obtain hydrogen-fluoride-doped graphene monoacetylene powder. For every 0.3 mmol of 1,4-dibromo-2,3,5,6-tetrafluorobenzene, 15 mL of N,N-dimethylformamide solution, 15 mL of triethylamine, 6 mg of Pd(PPh3)4, 0.9 mg of CuI, and 0.2 mmol of 1,3,5-triethynylbenzene are used.

[0020] In the method for preparing hydrogen-fluorine-doped graphene monoacetylene powder using polyhalogenated aromatic hydrocarbons and alkynyl compounds as starting materials, other polyhalogenated aromatic hydrocarbons (such as 1,4-dibromo-2,3-difluorobenzene and 1,4-dibromo-2-fluorobenzene) are used instead of 1,4-dibromo-2,3,5,6-tetrafluorobenzene to prepare graphene monoacetylene derivatives with different amounts of hydrogen and fluorine doping. Such graphene monoacetylene has a larger pore size, more active sites, and high thermal and chemical stability, effectively improving the electrochemical activity and lithium storage of graphene monoacetylene.

[0021] The second technical solution of the present invention:

[0022] (1) The hydrogen-fluorine-doped graphyne material provided by the present invention has a large pore size, multiple active sites, and high thermal stability and chemical stability, so that the hydrogen-fluorine-doped graphyne material has excellent electrochemical energy storage properties.

[0023] (2) The present invention adopts a bottom-up strategy to prepare graphyne materials, and prepares graphyne materials with precise doping of hydrogen and fluorine atoms and clear hybrid morphology through Sonogashira coupling reaction.

[0024] (3) The hydrogen-fluorine-doped graphene material prepared by the present invention is an excellent lithium-ion battery electrode material, showing an extraordinary energy storage effect. -1 The performance is 1155mAh g -1 The reversible capacity is almost the same as that of commercial graphite anode materials (300-350 mAh g -1 ) times; significantly promoted the application of graphyne materials in the field of electrochemical energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1The scanning electron microscope images (1-1) and (1-2) of hydrogen fluoride-doped graphyne (H3F4-GY) prepared in Example 1 at different magnifications;

[0026] Figure 2 The scanning electron micrographs (2-1) and (2-2) of hydrogen fluoride-doped graphyne (H5F2-GY) prepared in Example 2 at different magnifications are shown;

[0027] Figure 3 The scanning electron micrographs (3-1) and (3-2) of hydrogen fluoride-doped graphyne (H6F1-GY) prepared in Example 3 at different magnifications are shown;

[0028] Figure 4 This is an infrared spectrum of hydrogen-fluorine-doped graphyne (H3F4-GY) prepared in Example 1;

[0029] Figure 5 This is the nitrogen adsorption-desorption curve of hydrogen-fluorine-doped graphene (H3F4-GY) prepared in Example 1 (the inset is the pore size distribution diagram);

[0030] Figure 6 In order to use the hydrogen fluoride doped graphene (H3F4-GY) prepared in Example 1 of the present invention for the negative electrode of lithium ion battery at 50mAg -1 The cycle performance diagram (6-1) and rate performance diagram (6-2) under

[0031] Figure 7 In order to use the hydrogen fluoride doped graphene (H5F2-GY) prepared in Example 2 of the present invention for the negative electrode of lithium ion battery at 50mAg -1 The cycle performance diagram (7-1) and rate performance diagram (7-2) under

[0032] Figure 8 In order to use the hydrogen fluoride doped graphene (H6F1-GY) prepared in Example 3 of the present invention for the negative electrode of lithium ion battery at 50mAg -1 The cycle performance diagram (8-1) and rate performance diagram (8-2) below. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions and advantages of the present invention more clear, embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0034] An embodiment of the present invention provides a hydrogen-fluorine-doped graphyne structure and a preparation method thereof, which is characterized by having a large pore size, multiple active sites, and high thermal stability and chemical stability. It has excellent electrochemical energy storage properties and exhibits extraordinary energy storage effects when used as a negative electrode material for lithium-ion batteries.

[0035] In the present invention, the hydrogen-fluorine-doped graphyne material can be represented as H3F4-GY, H5F2-GY and H6F1-GY according to different doping amounts.

[0036] In an embodiment of the present invention, the structural formula of the hydrogen-fluorine-doped graphyne material is shown in formulas (1)-(3):

[0037]

[0038] The preparation method thereof is as follows:

[0039] The invention uses halogenated aromatic hydrocarbons and alkynyl compounds as starting materials, uses palladium catalysts and copper catalysts as catalytic systems, conducts a Sonogashira coupling reaction in a polar solvent, and couples the halogenated aromatic hydrocarbons through the acetylenic bond of alkynylbenzene to obtain hydrogen-fluorine-doped graphene alkynyl materials.

[0040] Specifically, in some embodiments of the present invention, the alkynyl compound monomer includes hexaethynylbenzene, 1,3,5-triethynylbenzene or 1,4-diethynylbenzene.

[0041] Specifically, in some embodiments of the present invention, the halogenated aromatic hydrocarbon is a polyhalogenated aromatic hydrocarbon, including 1,4-dibromo-2,3,5,6-tetrafluorobenzene, 1,4-dibromo-2,3-difluorobenzene or 1,4-dibromo-2-fluorobenzene.

[0042] Specifically, in some embodiments of the present invention, the polar solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, and toluene. These solvents can ensure efficient Sonogashira coupling reaction between monomers.

[0043] Specifically, in some embodiments of the present invention, the solvent is an alkaline organic solvent, and the alkaline organic solvent is selected from at least one of triethylamine, diisopropylamine and pyridine.

[0044] Specifically, in some embodiments of the present invention, the protective gas is selected from at least one of nitrogen, helium and argon.

[0045] Specifically, in some embodiments of the present invention, the first catalyst is a complex of Pd(PPh3)4 and CuI or a complex of PdCl2(PPh3)2 and CuI, preferably a complex of Pd(PPh3)4 and CuI.

[0046] Specifically, in some embodiments of the present invention, the copper material is selected from at least one of copper sheet, copper foam and cuprous iodide.

[0047] Specifically, in some embodiments of the present invention, the conditions of the coupling reaction include: a temperature of 60-120°C, such as 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, and any value within the range consisting of any two of the above values, preferably 80-110°C, and a time of 1-5 days, such as 1 day, 2 days, 3, and any value within the range consisting of any two of the above values, preferably 1 day.

[0048] The present invention will be further described below through specific examples.

[0049] In the following specific examples, the operations involved, if the conditions are not specified, were carried out according to conventional conditions or the conditions recommended by the manufacturer. The raw materials used, if the manufacturer and specifications are not specified, are all conventional products that can be obtained through commercial purchase.

[0050] Example 1 Synthesis of Graphdiyne H3F4-GY

[0051] Accurately weigh 0.3 mmol of 1,4-diethynyl-2,3,5,6-tetrafluorobenzene and dissolve it in 15 mL of N,N-dimethylformamide solution. Add 15 mL of triethylamine and introduce argon for 15 minutes. Then, add 6 mg of Pd(PPh3)4 and 0.9 mg of CuI and 0.2 mmol of 1,3,5-triethynylbenzene in sequence. Seal the system and stir the reaction at 80°C for 24 hours. After the reaction is completed, filter the mixture. The obtained black precipitate is washed three times with hydrochloric acid, distilled water, anhydrous ethanol and dichloromethane in sequence and dried to obtain graphene H3F4-GY powder. The scanning electron microscope image is shown in FIG. Figure 1 , indicating that F-GY has a spherical morphology; Figure 2 is the infrared spectrum of H3F4-GY, Figure 3 is the element distribution map of H3F4-GY, Figure 4 Figure 1 is a diagram of nitrogen adsorption and desorption of H3F4-GY.

[0052] Example 2 Synthesis of Two-Dimensional Graphyne Monoyne H5F2-GY

[0053] Accurately weigh 0.3 mmol of 1,4-diethynyl-2,3-difluorobenzene and dissolve it in 15 mL of N,N-dimethylformamide solution. Add 15 mL of triethylamine and introduce argon for 15 minutes. Then, add 6 mg of Pd(PPh3)4 and 0.9 mg of CuI and 0.2 mmol of 1,3,5-triethynylbenzene in sequence. Seal the system and stir the reaction at 80°C for 24 hours. After the reaction is completed, filter the mixture. The obtained black precipitate is washed three times with hydrochloric acid, distilled water, anhydrous ethanol and dichloromethane in sequence and dried to obtain H5F2-GY powder.

[0054] Example 3 Synthesis of Two-Dimensional Graphyne Monoyne H6F1-GY

[0055] Accurately weigh 0.3 mmol of 1,4-diethynyl-2-fluorobenzene and dissolve it in 15 mL of N,N-dimethylformamide solution. Add 15 mL of triethylamine and introduce argon for 15 minutes. Then, add 6 mg of Pd(PPh3)4, 0.9 mg of CuI and 0.2 mmol of 1,3,5-triethynylbenzene in sequence. Seal the system and stir the reaction at 80°C for 24 hours. After the reaction is completed, filter the mixture. The obtained black precipitate is washed three times with hydrochloric acid, distilled water, anhydrous ethanol and dichloromethane in sequence and dried to obtain H6F1-GY powder.

[0056] Example 4 Assembled into 2032 button lithium ion battery

[0057] In this example, the hydrogen-fluorine-doped graphene materials prepared in Examples 1 to 3 were used to prepare working negative electrodes. The electrodes were prepared by mixing 70 wt% hydrogen-fluorine-doped graphene materials with 20 wt% Ketjen black (KB) and 10 wt% polyvinylidene fluoride (PVDF) on copper foil. The obtained hydrogen-fluorine-doped graphene-based electrode sample was coated on copper foil, cut into a disk with a radius of 0.6 cm, and then dried in a vacuum oven at 120°C for 8 hours before being used as a working electrode. 2032-type button cells were assembled, and pure lithium foil was used as the counter electrode, separated from the working electrode by a Celgard 2500 polymer separator. The electrolyte was 1 M LiPF6 in EC / DEC (1:1, v / v). The cells were assembled in an argon-filled glove box with moisture and oxygen concentrations below 1 ppm.

[0058] Cyclic performance test: at 50mAg -1 At a current density of 100, the LAND battery test system was used to perform 100 cycle tests in the range of 0.005V and 3V to obtain the average coulombic efficiency and capacity retention rate. -1 The performance is 1155mAh g -1 The reversible capacity is almost the same as that of commercial graphite anode materials (300-350 mAh g -1 ) three times.

[0059] Rate performance test: LAND battery test system was used to test in the range of 0.05V and 3V, respectively at 50mAg -1 , 100mAg -1 , 200mAg -1 , 500mA g -1 , 1000mAg -1 , 2000mAg -15000mAg -1 , 50mAg -1 After 5 cycles, the battery capacity data at different current densities are obtained, such as Figure 6-2 , 7-2, 8-2.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing hydrogen-fluorine atom-doped graphene material, characterized in that: The following steps are involved: Using bromine- and fluorine-substituted halogenated aromatic hydrocarbons and alkynylbenzene compounds as starting materials, a palladium catalyst / copper catalyst composite catalytic system is used to carry out a Sonogashira cross-coupling reaction in a polar solvent adjusted to an alkaline environment and a protective gas. During the reaction, the bromine group of the halogenated aromatic hydrocarbon is in situ removed through the acetylenic bond of the alkynylbenzene compound, and the halogenated aromatic hydrocarbon is Sonogashira coupled to obtain a graphene-based material. The alkynylbenzene compound contains at least two acetylene groups, and the bromine substitution in the halogenated aromatic hydrocarbon containing bromine and fluorine substitution includes at least two bromine substitutions, and the molar ratio of bromine to alkynyl is 1:1.5-1.5:

1.

2. The method according to claim 1, characterized in that The alkynylbenzene compound is selected from hexaethynylbenzene, 1,3,5-triethynylbenzene or 1,4-diethynylbenzene. The halogenated aromatic hydrocarbon containing bromine and fluorine substitution is selected from 1,4-dibromo-2,3,5,6-tetrafluorobenzene, 1,4-dibromo-2,3-difluorobenzene or 1,4-dibromo-2-fluorobenzene.

3. The method according to claim 1, characterized in that The polar solvent is selected from N,N-dimethylformamide, tetrahydrofuran, and toluene, which can ensure efficient Sonogashira coupling reaction between monomers; the alkalinity is regulated by adding a base to the solvent to control the pH of the solvent to 8 to 13; the base is selected from triethylamine, diisopropylamine, pyridine, potassium carbonate, or sodium carbonate.

4. The method according to claim 1, characterized in that The protective gas is selected from at least one of nitrogen, helium and argon.

5. The method according to claim 1, characterized in that The palladium catalyst is selected from Pd(PPh3)4, Pd(PPh3)2Cl2 or Pd(dppf)Cl2; The copper catalyst is a monovalent copper catalyst selected from CuCl, CuBr, CuI or a Cu(I) complex dissolved from the surface of a copper sheet; The molar ratio of the palladium catalyst to the copper catalyst is 1:1 to 10:

1.

6. The method according to claim 1, characterized in that The Sonogashira cross-coupling reaction temperature is 60-120° C., and the reaction time is 24 hours to 5 days, preferably 80° C. for 24 hours.

7. The method according to claim 1, characterized in that The method for preparing graphene monoacetylene using halogenated aromatic hydrocarbons and alkynyl compounds as starting materials is as follows: 1,4-dibromo-2,3,5,6-tetrafluorobenzene is weighed and dissolved in N,N-dimethylformamide solution. Triethylamine is added and argon is introduced for 15 minutes. Then, Pd(PPh3)4, CuI, and 1,3,5-triethynylbenzene are added sequentially. The system is sealed and stirred at 80°C for 24 hours. After completion of the reaction, the resulting black precipitate is filtered and washed three times with hydrochloric acid, distilled water, anhydrous ethanol, and dichloromethane, followed by drying to obtain hydrogen-fluoride-doped graphene monoacetylene powder. For every 0.3 mmol of 1,4-dibromo-2,3,5,6-tetrafluorobenzene, 15 mL of N,N-dimethylformamide solution, 15 mL of triethylamine, 6 mg of Pd(PPh3)4, 0.9 mg of CuI, and 0.2 mmol of 1,3,5-triethynylbenzene are used.

8. A hydrogen-fluorine atom-doped graphene material prepared according to the method of any one of claims 1 to 7.

9. Use of the hydrogen-fluorine atom-doped graphyne material prepared by the method according to any one of claims 1 to 7 as an electrode material for lithium-ion batteries, especially as a negative electrode.

10. A lithium ion battery, characterized in that: The invention comprises a hydrogen-fluorine atom-doped graphene material prepared according to the method according to any one of claims 1 to 7.

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