In-situ doped graphylene composites of lithium trifluoromethanesulfonate, their preparation methods and applications

Abstract

This invention belongs to the field of lithium battery materials technology, specifically relating to a lithium trifluoromethanesulfonate in-situ doped graphylene composite material, its preparation method, and its application. The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphylene composite material is as follows: a one-step in-situ synthesis method is used, specifically, hexaethynylbenzene and lithium trifluoromethanesulfonate are mixed in a solvent, a catalyst is added, and the mixture is heated to react. The resulting reactants are then post-treated to finally obtain the lithium trifluoromethanesulfonate in-situ doped graphylene composite material. The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphylene composite material provided by this invention has a simple process, and the prepared composite material has good interfacial stability. Its application in the negative electrode of lithium-ion batteries can improve the electrochemical performance of the battery and extend its service life.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery material technology, specifically relating to a composite material of lithium trifluoromethanesulfonate in situ doped with graphylene and its preparation method and application. Background Technology

[0002] As the core of modern electrochemical energy storage, the further improvement of lithium-ion batteries depends on the innovation of anode materials. Among numerous candidate materials, graphyne has attracted much attention due to its unique sp-sp2 hybrid carbon atom network and intrinsically uniform pore structure. These properties are believed to be conducive to the rapid transport of lithium ions and provide abundant lithium storage sites. Therefore, graphyne and its composite materials have shown clear application potential in the field of lithium-ion battery anodes.

[0003] Current technologies in this field mainly focus on the preparation of pure graphyne and the exploration of its performance as a negative electrode material. A more common improvement strategy is to use a "two-step method" to prepare graphyne composite materials. First, a two-dimensional layered porous graphyne framework is independently synthesized through a cross-coupling reaction of precursors such as hexaethynylbenzene under the action of a catalyst. Then, in the second step, the synthesized graphyne is physically mixed or solution-immersed with target dopants or active materials such as silicon or metal oxides. This method relies on the high specific surface area and porosity of graphyne to load other components through physical adsorption, aiming to introduce high-capacity substances or utilize the conductive network of graphyne to buffer volume expansion.

[0004] However, this mainstream two-step physical mixing strategy has several inherent drawbacks that limit its practical application. First, this method struggles to achieve molecular-level uniform dispersion of dopants within graphyne, especially for salts like lithium trifluoromethanesulfonate, which readily aggregate on the surface or undergo only weak physical adsorption. These poorly bound dopants are prone to detaching from the pores or dissolving in the electrolyte during battery cycling, resulting in unsustainable modification effects. Second, due to weak interfacial bonding, the solid electrolyte interface film formed between the graphyne composite and the electrolyte is often unstable, undergoing continuous rupture and reconstruction during long-term cycling, constantly consuming active lithium and electrolyte, leading to accelerated capacity decay and shortened cycle life. Furthermore, the stepwise synthesis process is lengthy, involving multiple independent operations, increasing production complexity and time costs, hindering cost control for large-scale applications. Finally, existing methods fail to effectively construct stable and efficient ion transport channels within the graphyne framework; physically adsorbed dopants cannot continuously provide additional lithium-ion diffusion pathways, thus limiting the ion transport kinetics of the material under high-rate charge-discharge conditions.

[0005] For example, CN109626368A discloses an N-doped γ-type graphitic monoacetylene carbon material, its preparation method and application. Pyridine is used as the source of pyridine N, and pyridine and benzene / hexahalobenzene are used as precursors of sp2 hybrid carbon atoms. The method of synthesizing pyridine N-doped γ-type graphitic monoacetylene is carried out through mechanochemical interaction with calcium carbide (the source of sp hybrid atoms) and subsequent heat treatment. However, it is difficult to dope uniformly and the repeatability is poor when using ball milling. Long-term ball milling can also easily introduce some metal impurities to contaminate the product.

[0006] For example, the paper "Preparation and Lithium Storage Performance of Graphdiyne-Organic Conjugated Molecular Composite Material (Chen Yanhuan, Li Jiaofu, Liu Huibiao)" published in Acta Physico-Chimica Sinica, 2018, 34(9):1074-1079, utilizes a supramolecular chemistry method to achieve in-situ nitrogen doping of graphdiyne. By utilizing the strong π-π interaction between graphdiyne and organic conjugated molecules, a porphyrin / graphdiyne composite film was prepared in situ on the surface of a copper sheet. This composite film can be used directly as the negative electrode of a lithium-ion battery without any binder or conductive agent, effectively improving the specific capacity and stability of the lithium battery. However, there is a risk of it detaching from the copper sheet. When synthesizing the composite material on a copper sheet and assembling the battery by scraping off one side of the material to test the electrochemical performance, copper powder is easily scraped off as well, making it difficult to accurately obtain the specific quality of the material, thus leading to inaccurate data. Using copper sheets to synthesize materials is not easy to mass-produce. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing a composite material of lithium trifluoromethanesulfonate in situ doped with graphylene. The process is simple and the prepared composite material has good interfacial stability. When applied to the negative electrode of lithium-ion battery, it can improve the electrochemical performance of the battery and extend its service life.

[0008] The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphyne composite material is as follows: it is prepared by a one-step in-situ synthesis method, specifically by adding hexaethynylbenzene and lithium trifluoromethanesulfonate into a solvent and mixing them, then adding a catalyst and heating the reaction. The resulting reactants are post-treated to finally obtain the lithium trifluoromethanesulfonate in-situ doped graphyne composite material.

[0009] The catalyst is a soluble copper salt.

[0010] The solvent is pyridine, N,N-dimethylformamide, or tetrahydrofuran.

[0011] The catalyst is cuprous iodide.

[0012] The conditions for adding the catalyst and heating the reaction are: to carry out the reaction in a closed system under nitrogen or inert atmosphere, at a temperature of 60~120℃, for a reaction time of 12~72h.

[0013] The mass ratio of hexaethynylbenzene to lithium trifluoromethanesulfonate is 1:2 to 1:6.

[0014] The mass ratio of hexaethynylbenzene to catalyst is 5:1 to 16:1.

[0015] The post-processing steps involve cooling the obtained reactants, separating the solids, washing with acetonitrile, and vacuum drying.

[0016] A composite material in which lithium trifluoromethanesulfonate is in situ doped with graphynylene is prepared by the method described above.

[0017] Application of a composite material in situ doped with graphylene trifluoromethanesulfonate: the composite material is used in a lithium-ion battery anode composite material.

[0018] The graphyne synthesis precursor of this invention uses hexaethynylbenzene. This substance is a classic and essential monomer for the synthesis of graphyne; the six ethynyl groups in its molecular structure can undergo cross-coupling reactions under catalytic conditions to construct an sp-sp² hybrid two-dimensional graphyne framework. This is the basis for forming the main structure. The dopant used is lithium trifluoromethanesulfonate, which is required to be of battery-grade purity to minimize the adverse effects of impurities on electrochemical performance. + As an additional lithium source, it compensates for the irreversible capacity loss during the first charge and discharge of the battery; its CF3SO3 - Due to its unique chemical stability, the trifluoromethanesulfonate anion is pre-positioned within the graphyne structure, guiding the formation of a robust SEI film rich in stable components such as LiF during subsequent battery cycles. This invention uses pyridine as the solvent and a soluble copper salt (cuprous iodide) as the catalyst. Copper is an indispensable catalyst for the cross-coupling reaction of acetylene groups, and its surface or ions provide active sites for the nucleation and growth of graphyne.

[0019] The entire synthesis reaction of this invention is carried out under the protection of an inert gas (such as high-purity argon) or nitrogen to prevent oxygen and moisture in the air from negatively affecting the reaction precursors, catalysts, and lithium trifluoromethanesulfonate, which is sensitive to water and oxygen.

[0020] The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphylene composite material of the present invention adopts a "one-step in-situ synthesis method", and its detailed working steps are as follows:

[0021] Step 1: Preparation of precursor mixture solution

[0022] In a glove box filled with inert or nitrogen gas, hexaethynylbenzene and lithium trifluoromethanesulfonate are precisely weighed at a mass ratio of 1:6 to 1:2 and added together to a solvent. At room temperature, the solids are completely dissolved or fully dispersed by magnetic stirring to form a homogeneous mixed reaction solution. This step is crucial for ensuring the uniformity of subsequent doping.

[0023] Step 2: In-situ cross-coupling reaction

[0024] The above mixed reaction solution was transferred to a sealed reaction vessel, a catalyst was added, and the reaction system was heated to 60℃~120℃ and continued to react at this temperature for 12~72h.

[0025] During this process, hexaethynylbenzene undergoes a cross-coupling reaction under the action of a catalyst, gradually constructing a two-dimensional layered porous graphyne framework. At the same time, lithium trifluoromethanesulfonate dissolved in the reaction solution is captured in situ and physically by the extending and stacking graphyne layers, and is firmly confined in the gaps between the newly formed graphyne layers and in its inherent triangular pores.

[0026] Step 3: Separation and purification of the product

[0027] After the reaction is complete, the system is allowed to cool naturally to room temperature. The solid product is collected by filtration or centrifugation. Acetonitrile is then used as a washing solvent to wash the solid product multiple times. This is to selectively wash away lithium trifluoromethanesulfonate, unreacted monomers, and catalyst residues that were not successfully incorporated and were only physically adsorbed on the outer surface of graphyne, while retaining the dopants that have been successfully confined inside the structure.

[0028] Step 4: Drying and Collection

[0029] The washed solid product was placed in a vacuum drying oven and dried at 60°C for 6-12 hours to completely remove the solvent, finally obtaining a black, powdery lithium trifluoromethanesulfonate in-situ doped graphyne composite material.

[0030] The working principle of this invention is based on two aspects: "structural confinement" and "interface pre-modification." Unlike the traditional "two-step" physical adsorption method, this invention utilizes the kinetics and thermodynamics of graphyne's own growth during its "birth" process to "weave" the dopant as an inherent component of the reaction system into the final structure. This permanently fixes lithium trifluoromethanesulfonate within the nanopores and interlayers of graphyne, achieving uniform distribution at the molecular level and unprecedented binding strength, effectively preventing detachment during cycling. This invention, through in-situ doping, introduces a key component (CF3SO3) that promotes stable SEI film formation. -These confined anions are "pre-embedded" within the structure during the electrode material preparation stage. When the battery is first charged and discharged, these anions preferentially undergo reduction reactions inside and on the surface of the electrode material, reacting with Li. + Through synergistic effects, a uniform, dense, and LiF-rich stable SEI film is induced to form at the pores and interlayer of graphyne. This high-quality SEI film effectively inhibits the continuous decomposition of the electrolyte, significantly improving the cycle life and coulombic efficiency of the battery. The uniformly distributed lithium salt in this invention provides additional, low-resistance jumping sites for lithium ions. Combined with the excellent electronic conductivity of graphyne itself, this enhances the ionic conductivity and charge transfer kinetics of the electrode, thereby endowing the material with excellent rate performance. Therefore, this invention, through a "one-step in-situ synthesis method," fundamentally solves the key defects of existing technologies, creating a structurally stable, interface-superior, and performance-enhanced lithium-ion battery anode composite material.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] (1) This invention combines the two key steps of traditional “synthesis first, doping later” into a one-step in-situ synthesis, which significantly simplifies the process. The traditional two-step method takes a total of 84-96 hours (48-72 hours for graphdiyne synthesis, and 12-24 hours for doping and subsequent treatment), while the one-step process of this invention shortens the total time to 20-80 hours, greatly improving efficiency. In addition, it eliminates a separate heating, stirring, separation and drying process, directly reducing equipment occupation, energy consumption and labor costs, providing a strong cost competitive advantage for large-scale industrial production.

[0033] (2) The composite material prepared by the present invention has a stable structure and excellent electrochemical performance. By firmly confining lithium trifluoromethanesulfonate in the graphynylene structure, it exhibits electrochemical performance far exceeding that of traditional materials when used as a negative electrode of lithium-ion batteries. Attached Figure Description

[0034] Figure 1 The image shows a scanning electron microscope (SEM) image of the in-situ doped graphyne composite material of lithium trifluoromethanesulfonate prepared in Example 1.

[0035] Figure 2 The graph shows the rate performance of the lithium-ion battery of the in-situ doped graphyne composite material of lithium trifluoromethanesulfonate prepared in Example 1.

[0036] Figure 3 The image shows the lithium-ion battery cycle performance of the lithium trifluoromethanesulfonate in-situ doped graphyne composite material prepared in Example 1.

[0037] Figure 4 The first three charge-discharge curves of the lithium-ion battery made of lithium trifluoromethanesulfonate in situ doped with graphyne composite material prepared in Example 1 are shown.

[0038] Figure 5 Impedance diagram of lithium-ion battery of lithium trifluoromethanesulfonate in-situ doped graphyne composite material prepared in Example 1.

[0039] Figure 6 The cyclic voltammetry curve of the lithium-ion battery of the in-situ doped graphyne composite material of lithium trifluoromethanesulfonate prepared in Example 1 is shown. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments.

[0041] Example 1

[0042] The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphynylene composite material includes the following steps: In a glove box filled with inert gas, 50 mg of hexaethynylbenzene and 200 mg of lithium trifluoromethanesulfonate are added to 50 mL of pyridine and mixed. The mixture is magnetically stirred at room temperature to form a homogeneous mixed reaction solution. The reaction solution is transferred to a sealed reaction vessel, 5 mg of cuprous iodide is added, and the reaction system is heated to 80 °C and the reaction is continued at this temperature for 18 h. After the reaction is completed, the system is allowed to cool naturally to room temperature. The obtained solid product is collected by filtration. Subsequently, the solid product is washed multiple times with acetonitrile. The washed solid product is placed in a vacuum drying oven and dried at 60 °C for 12 h to finally obtain a black, powdery lithium trifluoromethanesulfonate in-situ doped graphynylene composite material.

[0043] Scanning electron microscope image of the prepared composite material, as shown Figure 1 As shown in the figure, the composite material exhibits an irregular structure with many small particles on the surface. This structure increases the specific surface area and exposes many active sites, which is beneficial to the stability of the SEI layer and the transfer of electrons, thereby effectively improving the electrochemical performance of the material.

[0044] The rate performance diagram of the lithium-ion battery of the prepared composite material is shown in the figure below. Figure 2 As shown, the discharge specific capacity is 580 mAh / g at a current density of 0.1 A / g, and it still maintains a high discharge specific capacity of 264 mAh / g when the current density is increased to 2 A / g. When the current density returns to 0.1 A / g, the discharge specific capacity can return to 570 mAh / g. This demonstrates that the composite material exhibits excellent rate performance.

[0045] The lithium-ion battery cycle performance diagram of the prepared composite material is shown in the figure below. Figure 3 As shown, after 300 cycles at a current density of 0.1 A / g, the discharge specific capacity can still be maintained at 500 mAh / g. The charging and discharging data at different cycle numbers overlap to some extent, indicating that the lithium-ion battery of the composite material has excellent cycle stability.

[0046] The discharge curves of the lithium-ion battery obtained from the composite material in the first three cycles are shown in the figure below. Figure 4 As shown, the discharge specific capacity and charge specific capacity in the first cycle are 897 mAh / g and 770 mAh / g, respectively, and the calculated coulombic efficiency in the first cycle reaches 85.8%. The GCD curves of the next two cycles almost overlap, indicating that the composite material has good cycle stability.

[0047] The lithium-ion battery impedance diagram of the prepared composite material is shown below. Figure 5 As shown, the diameter of the semicircle is smaller, and the fitted R... ct A resistance of 60Ω indicates rapid charge transfer during cycling. In the low-frequency region, the steeply sloping line indicates high Li-value. + And the efficiency of electron transport.

[0048] The cyclic voltammogram of the lithium-ion battery obtained from the composite material is shown in the figure below. Figure 6 As shown, the area of ​​the cyclic voltammetry curve gradually increases with increasing scan rate, but the shape remains essentially unchanged, indicating that the composite electrode has high reversibility and cyclic stability. This high reversibility of the redox process originates from the composite system of graphdiyne and lithium trifluoromethanesulfonate, which accelerates the transport of lithium ions and electrons and promotes lithium storage between layers.

[0049] Example 2

[0050] The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphylene composite material includes the following steps: In a glove box filled with inert gas, 50 mg of hexaethynylbenzene and 100 mg of lithium trifluoromethanesulfonate are added to 50 mL of pyridine and mixed. The mixture is magnetically stirred at room temperature to form a homogeneous mixed reaction solution. The reaction solution is transferred to a sealed reaction vessel, 4 mg of cuprous iodide is added, and the reaction system is heated to 60 °C and the reaction is continued at this temperature for 12 h. After the reaction is completed, the system is allowed to cool naturally to room temperature. The obtained solid product is collected by filtration. Subsequently, the solid product is washed multiple times with acetonitrile. The washed solid product is placed in a vacuum drying oven and dried at 60 °C for 6 h to finally obtain a black, powdery lithium trifluoromethanesulfonate in-situ doped graphylene composite material.

[0051] Example 3

[0052] The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphylene composite material includes the following steps: In a glove box filled with inert gas, 50 mg of hexaethynylbenzene and 300 mg of lithium trifluoromethanesulfonate are added to 50 mL of tetrahydrofuran and mixed. The mixture is magnetically stirred at room temperature to form a homogeneous reaction solution. The reaction solution is transferred to a sealed reaction vessel, and 3.3 mg of cuprous iodide is added. The reaction system is heated to 100°C and the reaction is continued at this temperature for 48 h. After the reaction is completed, the system is allowed to cool naturally to room temperature. The obtained solid product is collected by filtration. Subsequently, the solid product is washed multiple times with acetonitrile. The washed solid product is placed in a vacuum drying oven and dried at 60°C for 10 h to finally obtain a black, powdery lithium trifluoromethanesulfonate in-situ doped graphylene composite material.

[0053] Example 4

[0054] The preparation method of the lithium trifluoromethanesulfonate in-situ doped graphynylene composite material includes the following steps: In a glove box filled with inert gas, 50 mg of hexaethynylbenzene and 300 mg of lithium trifluoromethanesulfonate are added to 50 mL of N,N-dimethylformamide and mixed. The mixture is magnetically stirred at room temperature to form a homogeneous mixed reaction solution. The reaction solution is transferred to a sealed reaction vessel, 10 mg of cuprous iodide is added, and the reaction system is heated to 120 °C and the reaction is continued at this temperature for 72 h. After the reaction is completed, the system is allowed to cool naturally to room temperature. The obtained solid product is collected by filtration. Subsequently, the solid product is washed multiple times with acetonitrile. The washed solid product is placed in a vacuum drying oven and dried at 60 °C for 8 h to finally obtain a black, powdery lithium trifluoromethanesulfonate in-situ doped graphynylene composite material.

[0055] Comparative Example 1

[0056] The method for preparing graphyne includes the following steps: In a glove box filled with inert gas, 50 mg of hexaethynylbenzene is added to 50 mL of pyridine, transferred to a sealed reaction vessel, and 5 mg of cuprous iodide is added. The reaction system is heated to 80 °C and the reaction is continued at this temperature for 72 h. After the reaction is completed, the system is allowed to cool naturally to room temperature. The obtained solid product is collected by filtration. Subsequently, the solid product is washed multiple times with acetonitrile. The washed solid product is placed in a vacuum drying oven and dried at 60 °C for 12 h to finally obtain the graphyne material.

[0057] Comparative Example 2

[0058] The preparation method of the lithium trifluoromethanesulfonate-doped graphyne composite material includes the following steps: In a glove box filled with inert gas, 50 mg of hexaethynylbenzene is added to 50 mL of pyridine, transferred to a sealed reaction vessel, and 5 mg of cuprous iodide is added. The reaction system is heated to 80°C and the reaction is continued at this temperature for 72 h. After the reaction is completed, the system is allowed to cool naturally to room temperature. The obtained solid product is collected by filtration. Subsequently, the solid product is washed multiple times with acetonitrile. The washed solid product is placed in a vacuum drying oven and dried at 60°C for 12 h to finally obtain a black, powdery graphyne material. In a glove box filled with inert gas, graphyne and lithium trifluoromethanesulfonate are placed in a ball mill jar and ball-milled in a planetary ball mill for 12 h to obtain the lithium trifluoromethanesulfonate-doped graphyne composite material.

[0059] Comparative Example 3

[0060] The preparation method of the lithium trifluoromethanesulfonate-doped graphyne composite material includes the following steps: In a glove box filled with inert gas, 50 mg of hexaethynylbenzene is added to 50 mL of pyridine, transferred to a sealed reaction vessel, and 5 mg of cuprous iodide is added. The reaction system is heated to 80°C and the reaction is continued at this temperature for 72 h. After the reaction is completed, the system is allowed to cool naturally to room temperature. The obtained solid product is collected by filtration. Subsequently, the solid product is washed multiple times with acetonitrile. The washed solid product is placed in a vacuum drying oven and dried at 60°C for 12 h to finally obtain a black, powdery graphyne material. Graphyne and lithium trifluoromethanesulfonate are ground and mixed evenly in a mortar and placed in a tube furnace for heat treatment at 200°C for 16 h to obtain the lithium trifluoromethanesulfonate-doped graphyne composite material.

[0061] Comparative Example 4

[0062] The preparation method of the lithium hexafluorophosphate in-situ doped graphynylene composite material includes the following steps: In a glove box filled with inert gas, 50 mg of hexaethynylbenzene and 200 mg of lithium hexafluorophosphate are added to 50 mL of pyridine and mixed. The mixture is magnetically stirred at room temperature to form a homogeneous mixed reaction solution. The reaction solution is transferred to a sealed reaction vessel, 5 mg of cuprous iodide is added, and the reaction system is heated to 80 °C and the reaction is continued at this temperature for 18 h. After the reaction is completed, the system is allowed to cool naturally to room temperature. The obtained solid product is collected by filtration. Subsequently, the solid product is washed multiple times with acetonitrile. The washed solid product is placed in a vacuum drying oven and dried at 60 °C for 12 h to finally obtain the lithium hexafluorophosphate in-situ doped graphynylene composite material.

[0063] The composite materials prepared in the above examples and comparative examples were weighed separately with polyvinylidene fluoride and carbon black at a certain mass ratio (8:1:1), placed in an agate mortar, and then an appropriate amount of N-methylpyrrolidone was added and ground thoroughly to form a uniform and viscous slurry. The uniformly ground slurry was coated onto the current collector copper foil with a scraper to a thickness of 100 μm. The coated copper foil was then placed in a vacuum drying oven and heated at 80°C for 12 hours. After the temperature of the vacuum drying oven dropped to room temperature, it was cut into electrode sheets with a diameter of 12 mm, and the mass of the active material was controlled at 1 mg / cm³. 2 The button cells were assembled in an argon-filled glove box, where the water and oxygen content were both below 0.01 ppm. CR2032 battery casings were used, with lithium foil as the positive electrode. A mixed solution of 0.8 M LiPF6 dissolved in ethylene carbonate (EC) / diethyl carbonate (DEC) (v:v=1:1) was used as the electrolyte, and a Celgard 2500 membrane was used as the separator. The assembled batteries were subjected to performance testing, and the results are shown in Table 1.

[0064] Table 1 Test Results

[0065]

[0066] As can be seen from the above, after 300 charge-discharge cycles, the capacity retention rate of the material of this invention is as high as 85.2%, which is much higher than that of the control group. This directly proves that the stable SEI film and robust composite structure formed by in-situ doping can effectively inhibit the failure of active materials and the continuous decomposition of electrolyte, thus solving the core problem of rapid capacity decay.

[0067] At a high rate of 2 A / g, Example 1 still provides a high capacity of 264 mAh / g, while Comparative Example 1 provides a high capacity of 200 mAh / g, meaning Example 1 has 1.3 times the capacity of Comparative Example 1. This indicates that the confined lithium trifluoromethanesulfonate, together with the inherent channels of graphyne, constructs an ultrafast ion transport pathway, giving the battery excellent fast-charging potential.

[0068] The invention has a higher initial coulombic efficiency (85.8%), which means less irreversible lithium loss during the first charge and discharge process, and more lithium ions can be used for subsequent reversible cycles, directly improving the battery's energy density and overall energy efficiency.

Claims

1. A method for preparing a composite material of lithium trifluoromethanesulfonate in situ doped with graphynylene, characterized in that: The product was prepared by a one-step in-situ synthesis method, specifically by mixing hexaethynylbenzene and lithium trifluoromethanesulfonate in a solvent, adding a catalyst and heating the reaction. The resulting reactants were then post-treated to finally obtain a composite material of lithium trifluoromethanesulfonate in-situ doped with graphyne. The catalyst is cuprous iodide. The conditions for adding the catalyst and heating the reaction are: to carry out the reaction in a closed environment under nitrogen or inert atmosphere, at a temperature of 60~120℃, and for a reaction time of 12~72h. The mass ratio of hexaethynylbenzene to lithium trifluoromethanesulfonate is 1:2 to 1:6; The mass ratio of hexaethynylbenzene to catalyst is 5:1 to 16:

1.

2. The method for preparing the lithium trifluoromethanesulfonate in-situ doped graphylene composite material according to claim 1, characterized in that: The solvent is pyridine, N,N-dimethylformamide, or tetrahydrofuran.

3. The method for preparing the lithium trifluoromethanesulfonate in-situ doped graphylene composite material according to claim 1, characterized in that: The post-processing steps involve cooling the obtained reactants, separating the solids, washing with acetonitrile, and vacuum drying.

4. A composite material in situ doped with graphylene trifluoromethanesulfonate, characterized in that: It is prepared by the method of preparing the lithium trifluoromethanesulfonate in-situ doped graphylene composite material according to any one of claims 1-3.

5. The application of the composite material of lithium trifluoromethanesulfonate in situ doped with graphynylene as described in claim 4, characterized in that: The composite material is used in the negative electrode of a lithium-ion battery.

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