Fluorinated modified MXene-based conductive composite material and preparation method thereof

Abstract

The invention relates to a fluorinated modified MXene-based conductive composite material and a preparation method thereof, and belongs to the technical field of composite materials, Ti3AlC2 is subjected to fluorinated etching, a fluorine group is introduced, Ni < 2 + >, Co < 2 + > and La < 3 + > react with S < 2 > generated by disproportionation reaction of sulfur powder under a hydrothermal condition to generate metal sulfide nanocrystals, the metal sulfide nanocrystals are anchored on the surface of fluorinated MXene powder, and the fluorinated modified MXene-based conductive composite material is obtained. Meanwhile, ammonium fluoride supplements fluorine ions to further regulate and control surface groups, melamine is induced to form a titanium vacancy defect in subsequent heat treatment, active sites are enriched, an electron transmission path is optimized, nitrogen doping and heat treatment of dopamine form a nitrogen-doped carbon layer, a three-dimensional conductive network is constructed, the interface bonding force is enhanced, and the conductivity of the electrode is improved. In-situ generation of ZnIn2S4 and interlayer insertion of graphene oxide increase additional active sites and effectively inhibit agglomeration, so that the specific capacitance and cycling stability of the fluorinated modified MXene-based conductive composite material are synergistically improved.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology and relates to a fluorinated modified MXene-based conductive composite material and its preparation method. Background Technology

[0002] MXene nanosheets, as two-dimensional transition metal carbide / nitride materials with atomic-level thickness, have shown great application value in energy storage, flexible sensing, and electrocatalysis due to their ultra-high electrical conductivity, large specific surface area, tunable interlayer spacing, and abundant surface functional groups, becoming a research hotspot for next-generation conductive functional materials. The general formula for this type of material is M... n+1 X n T x The functional groups such as -OH, -O, and -F on its surface endow it with unique physicochemical properties. When combined with other materials, it can also achieve a synergistic improvement in conductivity and functionality. It is widely used in the preparation of electrodes or dielectric layers for devices such as supercapacitors, alkali metal ion batteries, and triboelectric sensors.

[0003] Chinese invention patent application CN119775576A discloses an MXene / two-dimensional conductive MOF composite material and its derivative materials, flexible electrodes and applications. The preparation method is as follows: a reaction solution containing monolayer MXene, metal ions, ligands and initiators is reacted to obtain the MXene / two-dimensional conductive MOF composite material, which retains the original structure of MXene and C-MOF and has the excellent properties of both. When used as a flexible electrode, the supercapacitor performance of flexible supercapacitors is improved.

[0004] The MXene / two-dimensional conductive MOF composite material in the above scheme relies only on the simple composite of a single layer of MXene and MOF without targeted optimization of the MXene surface groups, and lacks multi-component synergistic doping and interlayer support design, which leads to easy stacking between material layers and obstruction of ion transport paths. At the same time, the interfacial bonding force between MOF and MXene is weak, and the active components are easy to fall off after long-term cycling, which limits the further improvement of the material's specific capacitance and cycle stability. Summary of the Invention

[0005] The purpose of this invention is to provide a fluorinated modified MXene-based conductive composite material and its preparation method. By fluorination etching, multi-metal sulfide doping, nitrogen doping, and ZnIn2S4 / graphene oxide composite, the specific capacitance, conductivity, and cycle stability of the material are improved, making it suitable for energy storage and conductivity requirements in multiple fields.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a fluorinated modified MXene-based conductive composite material includes the following steps: Step 1: Fluoride etching of Ti3AlC2 using concentrated hydrochloric acid and lithium fluoride to obtain fluorinated MXene powder.

[0007] Step 2: Under hydrothermal conditions, Ni from nickel source, cobalt source, and lanthanum source... 2+ Co 2+ La 3+ S is uniformly deposited on the surface of fluorinated MXene powder and reacted with sulfur powder through a disproportionation reaction. 2- The reaction, combined with ammonium fluoride to optimize surface groups, yields fluorinated modified MXene powder.

[0008] Step 3: Using dopamine hydrochloride as the nitrogen source, nitrogen is doped into the fluorinated modified MXene powder, and then heat-treated to obtain nitrogen-doped fluorinated modified MXene powder.

[0009] Step 4: Under hydrothermal conditions, Zn 2+ In 3+ With S 2- In-situ reaction generates ZnIn2S4, which is anchored on nitrogen-doped fluorinated modified MXene powder. Simultaneously, graphene oxide is inserted into the interlayer of nitrogen-doped fluorinated modified MXene powder to obtain a fluorinated modified MXene-based conductive composite material.

[0010] Furthermore, the specific preparation process of the fluorinated modified MXene-based conductive composite material is as follows: Nitrogen-doped fluorinated modified MXene powder, anhydrous ethanol, and deionized water were added to a high-pressure reactor and ultrasonically dispersed for 20-30 minutes. Zinc salt solution and indium salt solution were added and stirred for 40-50 minutes. Thioacetamide and graphene oxide were then added and stirred for 20-30 minutes. Air was purged with nitrogen and the mixture was reacted at 120-130°C for 2-3 hours. The mixture was then naturally cooled to room temperature, washed, and dried to obtain the fluorinated modified MXene-based conductive composite material.

[0011] Furthermore, the ratio of nitrogen-doped fluorinated modified MXene powder, anhydrous ethanol, deionized water, zinc salt solution, indium salt solution, thioacetamide, and graphene oxide is 1-1.5 g: 1-1.4 L: 1-1.4 L: 2-3 mmol: 4-6 mmol: 12-16 mmol: 0.2-0.4 g.

[0012] Furthermore, the zinc salt solution is one of zinc chloride and zinc acetate.

[0013] Furthermore, the indium salt solution is one of indium iodide and indium chloride.

[0014] Furthermore, the specific preparation process of nitrogen-doped fluorinated modified MXene powder is as follows: Fluorinated MXene powder and deionized water were added to a reaction vessel and stirred until homogeneous. The pH of the solution was adjusted to 8.5 and stirred for 30-40 min. A dopamine hydrochloride solution with a concentration of 8 g / L was slowly added dropwise. The mixture was stirred under dark conditions, centrifuged, washed, and dried. The temperature was increased to 400-450℃ at a rate of 5℃ / min and heated for 2-3 h under a nitrogen atmosphere to obtain nitrogen-doped fluorinated MXene powder.

[0015] Furthermore, the ratio of fluorinated modified MXene powder, deionized water, and dopamine hydrochloride solution is 2.2-3.2g: 5-6L: 5-6L.

[0016] Furthermore, the specific preparation process of fluorinated modified MXene powder is as follows: A 50 vol% aqueous ethanol solution, nickel chloride hexahydrate, lanthanum nitrate, cobalt salt, urea, ammonium fluoride, sulfur powder, and melamine were added to a reaction vessel and stirred until completely dissolved. Then, fluorinated MXene powder was added to the reaction vessel and ultrasonically dispersed for 30-40 minutes. The mixture was then hydrothermally reacted at 120-130℃ for 4-5 hours. After washing and drying, fluorinated modified MXene powder was obtained.

[0017] Furthermore, the ratio of the amounts of ethanol aqueous solution, nickel chloride hexahydrate, lanthanum nitrate, cobalt salt, urea, ammonium fluoride, sulfur powder, melamine, and fluorinated MXene powder is 400-500mL: 1.2-1.8g: 0.05-0.07g: 2.4-3.2g: 4.5-5.5g: 0.9-1.3g: 3-5g: 0.5-0.7g: 3.0-4.0g.

[0018] Furthermore, the cobalt salt is one of cobalt chloride hexahydrate and cobalt nitrate.

[0019] Furthermore, the specific preparation process of fluorinated MXene powder is as follows: Pure water, concentrated hydrochloric acid, and lithium fluoride were added sequentially to the reactor and stirred for 15-25 minutes. Ti3AlC2 was added in five portions, and the mixture was stirred at 55-65℃ for 24-26 hours. The mixture was then sonicated, the pH was adjusted to 7, and the mixture was dried to obtain fluorinated MXene powder.

[0020] Furthermore, the ratio of pure water, concentrated hydrochloric acid, lithium fluoride, and Ti3AlC2 is 100-150mL:100-150mL:10-15g:10g.

[0021] A fluorinated modified MXene-based conductive composite material is prepared by etching Ti3AlC2 with concentrated hydrochloric acid and lithium fluoride, followed by hydrothermal treatment of Ni... 2+ Co 2+ La 3+ S generated by the disproportionation reaction with sulfur powder2- The reaction is combined with ammonium fluoride to optimize the surface groups, then doped with dopamine hydrochloride as the nitrogen source and subjected to heat treatment, and finally Zn is subjected to hydrothermal conditions. 2+ In 3+ With S 2- ZnIn2S4 is generated in situ and anchored on the powder, while graphene oxide is inserted into its interlayer.

[0022] The beneficial effects of this invention are: 1. This invention introduces fluorine groups by fluorination etching of Ti3AlC2 with concentrated hydrochloric acid and lithium fluoride, followed by Ni under hydrothermal conditions. 2+ Co 2+ La 3+ S generated by the disproportionation reaction with sulfur powder 2− The reaction generates metal sulfide nanocrystals that are anchored on the surface of fluorinated MXene powder. Simultaneously, ammonium fluoride replenishes fluoride ions to further regulate surface functional groups. Melamine, as a nitrogen source and defect inducer, pyrolyzes to produce amino groups during hydrothermal treatment and subsequent processing. On the one hand, it induces the formation of titanium vacancy (VTi) defects on the MXene surface, expanding the range of unsaturated coordination sites. On the other hand, it provides nitrogen atoms to participate in MXene lattice doping, forming Ti-N bonds to strengthen interfacial bonding, enriching active sites and optimizing electron transport paths. Nitrogen doping of dopamine and heat treatment form a nitrogen-doped carbon layer, constructing a three-dimensional conductive network and strengthening interfacial bonding. The in-situ generation of ZnIn2S4 and the interlayer insertion of graphene oxide not only add additional active sites but also effectively inhibit MXene aggregation. Furthermore, the pyrolysis of melamine can also assist in the construction of a 3D porous structure, further alleviating MXene interlayer stacking. Together with graphene oxide, it ensures unobstructed ion transport channels and synergistically improves the specific capacitance, conductivity, and cycle stability of the fluorinated modified MXene-based conductive composite material.

[0023] 2. This invention provides abundant redox active sites for the material by introducing metal sulfide nanocrystals and ZnIn2S4 nanosheets. The nitrogen-doped carbon layer and the high conductivity of MXene form a synergy, accelerating charge transport and making the material's conductivity significantly better than that of single MXene or simple composite systems. Graphene oxide, as an interlayer support agent, effectively alleviates the interlayer stacking problem of MXene and ensures the smooth flow of ion transport channels. Meanwhile, the bridging and chemical bonding anchoring of polydopamine enhances the interfacial interaction and improves the structural stability of the material, enabling it to maintain a high capacitance retention rate after multiple cycles. This overcomes the defects of traditional composite materials, such as easy shedding of active components and easy structural collapse during cycling.

[0024] 3. The nickel source, cobalt source, zinc salt, indium salt, etc. in this invention can all be selected from a variety of soluble salts, without the need for specific reagents, which reduces the preparation cost and operation difficulty; the multi-step modification process works together, and the product of each step provides an ideal substrate for subsequent reactions, realizing the connection between steps and ensuring the uniform dispersion and synergistic effect of each component; the finally prepared fluorinated modified MXene-based conductive composite material, with its comprehensive advantages of high specific capacitance, high conductivity and long cycle stability, can be widely adapted to the needs of multiple fields such as supercapacitors, alkali metal ion batteries, and flexible sensing, providing a new path for the research and development of high-performance energy storage and conductive materials. Detailed Implementation

[0025] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following detailed description of the specific implementation methods, features and effects of the present invention is provided in conjunction with preferred embodiments.

[0026] Example 1: This example provides a fluorinated modified MXene-based conductive composite material, prepared through the following steps: S1: 100 mL of pure water, 100 mL of concentrated hydrochloric acid (concentration of 36%) and 10 g of lithium fluoride were added to the reaction vessel in sequence and stirred for 15 min. 10 g of MAX (Ti3AlC2) was added in five portions and stirred at 55 °C for 24 h. After centrifugation and washing with water, the mixture was ultrasonically treated, the pH was adjusted to 7, and the mixture was vacuum dried at 40 °C for 12 h to obtain fluorinated MXene powder.

[0027] Concentrated hydrochloric acid provides an acidic environment, and the HF generated by the reaction with lithium fluoride acts as a key etching agent, which can selectively break the relatively weak Ti-Al bonds in Ti3AlC2, thereby efficiently removing the Al layer. At the same time, fluoride ions combine with Ti atoms on the MXene surface, introducing fluorine groups, optimizing the surface chemical properties of the material, and obtaining fluorinated MXene powder with a stable structure and fluorine groups on the surface.

[0028] S2: 400 mL of 50 vol% ethanol aqueous solution, 1.2 g nickel chloride hexahydrate (analytical grade), 0.05 g lanthanum nitrate, 2.4 g cobalt chloride hexahydrate (analytical grade), 4.5 g urea (analytical grade), 0.9 g ammonium fluoride (analytical grade), 3 g sulfur powder and 0.5 g melamine were added to the reaction vessel and stirred until completely dissolved. Then, 3.0 g fluorinated MXene powder was added to the reaction vessel and ultrasonically dispersed for 30 min. The reaction was carried out hydrothermally at 120 °C for 4 h. After the reaction was completed, the supernatant was washed with a large amount of deionized water until the pH value was neutral to remove unreacted reagents. The supernatant was dried at 70 °C for 12 h to obtain fluorinated modified MXene powder.

[0029] The ethanol-water solution provides a stable dispersion system for the reaction, while urea acts as a slow-release alkali source, slowly decomposing and releasing ammonia under hydrothermal conditions. The pH of the system is gradually adjusted to allow Ni to react. 2+ Co 2+ La 3+ S is uniformly deposited on the surface of fluorinated MXene powder and reacts with sulfur powder in a hydrothermal environment to generate S. 2- The reaction forms a metal sulfide nanocrystal anchoring structure, while sulfur is doped into the MXene lattice, and ammonium fluoride replenishes fluoride ions, further optimizing the composition of terminal groups on the MXene surface; the amino groups generated by melamine pyrolysis interact with the hydroxyl groups on the MXene surface, and the strong coordination ability of the amino groups induces some atoms on the MXene surface to detach, forming titanium vacancy defects.

[0030] S3: Add 2.2g of fluorinated modified MXene powder and 5L of deionized water to a reaction vessel, stir evenly, add tris(hydroxymethyl)aminomethane (Tris) and adjust the pH of the solution to 8.5, stir at 700r / min for 30min, slowly add 5L of 8g / L dopamine hydrochloride solution, stir for 30min in the dark, centrifuge, wash the precipitate three times with deionized water, freeze dry, heat the dried powder at a heating rate of 5℃ / min, heat at 400℃ and under nitrogen protection for 2h to obtain nitrogen-doped fluorinated modified MXene powder.

[0031] Dopamine self-polymerizes in aqueous solution to form a polydopamine layer, which tightly coats the surface of fluorinated MXene powder. On the one hand, it acts as an interfacial bridge to enhance the binding force with the active components. On the other hand, the amino and hydroxyl groups it contains can combine with the surface groups of fluorinated MXene powder, thus coating the outside of the fluorinated MXene powder. Freeze-drying preserves the porous structure of the material, and then heat treatment not only consolidates the sulfur doping effect and optimizes the electronic structure, but also promotes the partial carbonization of polydopamine to form a nitrogen-doped carbon layer, thus constructing a conductive network.

[0032] S4: 1g of nitrogen-doped fluorinated modified MXene powder, 1L of anhydrous ethanol and 1L of deionized water were added to a high-pressure reactor and ultrasonically dispersed for 20min. 2mmol of zinc acetate (analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.) and 4mmol of indium iodide (analytical grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) were added and stirred for 40min. Then, 12mmol of thioacetamide (analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.) and 0.2g of graphene oxide (diameter 0.5-3μm > 99wt%, purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.) were added and stirred for 20min. Air was purged with nitrogen and reacted at 120℃ for 2h. The mixture was naturally cooled to room temperature, washed three times with water and ethanol, and freeze-dried to obtain the fluorinated modified MXene-based conductive composite material.

[0033] The mixture of anhydrous ethanol and deionized water ensures the uniform dispersion of nitrogen-doped fluorinated modified MXene powder and improves the solubility of zinc acetate and indium iodide. Graphene oxide acts as an interlayer support agent, inserted into the interlayer of nitrogen-doped fluorinated modified MXene powder to prevent its aggregation and provide additional active sites and conductive channels. Zinc and indium ions in zinc acetate and indium iodide react with thioacetamide in situ under hydrothermal conditions to generate ultrathin ZnIn2S4 nanosheets, which are anchored on the surface of nitrogen-doped fluorinated modified MXene powder through a combination of chemical bonding and physical adsorption, resulting in a fluorinated modified MXene-based conductive composite material with both high conductivity and a stable structure.

[0034] Example 2: This example provides a fluorinated modified MXene-based conductive composite material, prepared through the following steps: S1: 125 mL of pure water, 125 mL of concentrated hydrochloric acid (concentration of 37%) and 12.5 g of lithium fluoride were added to the reaction vessel in sequence and stirred for 20 min. 10 g of MAX (Ti3AlC2) was added in five portions and stirred at 60 °C for 25 h. After centrifugation and washing with water, the mixture was ultrasonically treated, the pH was adjusted to 7, and the mixture was vacuum dried at 45 °C for 13 h to obtain fluorinated MXene powder.

[0035] S2: 450 mL of 50 vol% ethanol aqueous solution, 1.5 g nickel chloride hexahydrate (analytical grade), 0.06 g lanthanum nitrate, 2.8 g cobalt chloride hexahydrate (analytical grade), 5.0 g urea (analytical grade), 1.1 g ammonium fluoride (analytical grade), 4 g sulfur powder and 0.6 g melamine were added to the reaction vessel and stirred until completely dissolved. Then, 3.5 g fluorinated MXene powder was added to the reaction vessel and ultrasonically dispersed for 35 min. The reaction was carried out hydrothermally at 125 °C for 4.5 h. After the reaction was completed, the supernatant was washed with a large amount of deionized water until the pH value was neutral to remove unreacted reagents. The supernatant was dried at 75 °C for 13 h to obtain fluorinated modified MXene powder.

[0036] S3: Add 2.7g of fluorinated modified MXene powder and 5.5L of deionized water to a reaction vessel, stir evenly, add tris(hydroxymethyl)aminomethane (Tris) and adjust the pH of the solution to 8.5, stir at 800r / min for 35min, slowly add 5.5L of 8g / L dopamine hydrochloride solution, stir for 35min in the dark, centrifuge, wash the precipitate 4 times with deionized water, freeze dry, heat the dried powder at a heating rate of 5℃ / min, heat at 425℃ and under nitrogen protection for 2.5h to obtain nitrogen-doped fluorinated modified MXene powder.

[0037] S4: 1.25 g of nitrogen-doped fluorinated modified MXene powder, 1.2 L of anhydrous ethanol and 1.2 L of deionized water were added to a high-pressure reactor and ultrasonically dispersed for 25 min. Then, 2.5 mmol of zinc acetate (analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.) and 5 mmol of indium iodide (analytical grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) were added and stirred for 45 min. Then, 14 mmol of thioacetamide (analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.) and 0.3 g of graphene oxide (diameter 0.5-3 μm > 99 wt%, purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.) were added and stirred for 25 min. The air was purged with nitrogen and reacted at 125 °C for 2.5 h. After naturally cooling to room temperature, the mixture was washed three times with water and ethanol and freeze-dried to obtain the fluorinated modified MXene-based conductive composite material.

[0038] Example 3: This example provides a fluorinated modified MXene-based conductive composite material, prepared through the following steps: S1: 150 mL of pure water, 150 mL of concentrated hydrochloric acid (concentration of 38%) and 15 g of lithium fluoride were added to the reaction vessel in sequence and stirred for 25 min. 10 g of MAX (Ti3AlC2) was added in five portions and stirred at 65 °C for 26 h. After centrifugation and washing with water, the mixture was ultrasonically treated, the pH was adjusted to 7, and the mixture was vacuum dried at 50 °C for 14 h to obtain fluorinated MXene powder.

[0039] S2: Add 500 mL of 50 vol% ethanol aqueous solution, 1.8 g of nickel chloride hexahydrate (analytical grade), 0.07 g of lanthanum nitrate, 3.2 g of cobalt chloride hexahydrate (analytical grade), 5.5 g of urea (analytical grade), 1.3 g of ammonium fluoride (analytical grade), 5 g of sulfur powder and 0.7 g of melamine to a reaction vessel and stir until completely dissolved. Then add 4.0 g of fluorinated MXene powder to the reaction vessel and ultrasonically disperse for 40 min. Perform hydrothermal reaction at 130 °C for 5 h. After the reaction is completed, wash with a large amount of deionized water until the pH of the supernatant is neutral to remove unreacted reagents. Dry at 80 °C for 14 h to obtain fluorinated modified MXene powder.

[0040] S3: Add 3.2g of fluorinated modified MXene powder and 6L of deionized water to a reaction vessel, stir evenly, add tris(hydroxymethyl)aminomethane (Tris) and adjust the pH of the solution to 8.5, stir at 900r / min for 40min, slowly add 6L of 8g / L dopamine hydrochloride solution, stir for 40min in the dark, centrifuge, wash the precipitate 5 times with deionized water, freeze dry, heat the dried powder at a heating rate of 5℃ / min, heat at 450℃ and under nitrogen protection for 3h to obtain nitrogen-doped fluorinated modified MXene powder.

[0041] S4: 1.5 g of nitrogen-doped fluorinated modified MXene powder, 1.4 L of anhydrous ethanol and 1.4 L of deionized water were added to a high-pressure reactor and ultrasonically dispersed for 30 min. Then, 3 mmol of zinc acetate (analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.) and 6 mmol of indium iodide (analytical grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) were added and stirred for 50 min. Then, 16 mmol of thioacetamide (analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.) and 0.4 g of graphene oxide (diameter 0.5-3 μm > 99 wt%, purchased from Zhongke Leiming (Beijing) Technology Co., Ltd.) were added and stirred for 30 min. The air was purged with nitrogen and reacted at 130 °C for 3 h. After naturally cooling to room temperature, the mixture was washed 5 times with water and ethanol and freeze-dried to obtain the fluorinated modified MXene-based conductive composite material.

[0042] Example 4: This example provides a fluorinated modified MXene-based conductive composite material. The difference from Example 1 is that cobalt nitrate is used instead of cobalt chloride hexahydrate in step S2.

[0043] Example 5: This example provides a fluorinated modified MXene-based conductive composite material. The difference from Example 1 is that zinc chloride is used instead of zinc acetate in step S4.

[0044] Example 6: This example provides a fluorinated modified MXene-based conductive composite material. The difference from Example 1 is that indium chloride is used instead of indium iodide in step S4.

[0045] Comparative Example 1: This comparative example provides a fluorinated modified MXene-based conductive composite material. The difference from Example 1 is that step S2 is omitted, and in step S3, the fluorinated MXene powder prepared in step S1 is used instead of the fluorinated modified MXene powder.

[0046] Comparative Example 2: This comparative example provides a fluorinated modified MXene-based conductive composite material. The difference from Example 1 is that step S3 is omitted, and in step S4, the fluorinated modified MXene powder prepared in step S2 is used instead of the nitrogen-doped fluorinated modified MXene powder.

[0047] Comparative Example 3: This comparative example provides a fluorinated modified MXene-based conductive composite material. The difference from Example 1 is that step S4 is not performed. The nitrogen-doped fluorinated modified MXene powder prepared in step S3 is the fluorinated modified MXene-based conductive composite material.

[0048] The fluorinated modified MXene-based conductive composite materials prepared in Examples 1-6 and Comparative Examples 1-3 were cut into 1×1cm pieces as working electrodes, silver / silver chloride as reference electrodes, and platinum sheet electrodes as counter electrodes. 1M sulfuric acid was used as the electrolyte solution. The materials were tested using an electrochemical workstation, cyclically 8000 times at a current of 2A, to test the specific capacitance and capacitance retention rate. The conductivity of the materials was also tested using the four-probe method.

[0049] The test results are shown in the table below: Table 1 Performance Test Overview As shown in Table 1, the fluorinated modified MXene-based conductive composite materials of Examples 1-6 exhibit better specific capacitance, cycling stability, and conductivity than those of Comparative Examples 1-3. This may be because fluorinated MXene provides a highly conductive substrate, metal sulfides and ZnIn2S4 enrich active sites to enhance pseudocapacitance, nitrogen-doped carbon layers optimize the conductive network, graphene oxide inhibits aggregation and broadens ion channels, and the products of each step provide an ideal substrate for subsequent reactions, ensuring rapid charge transport, efficient ion diffusion, and structural stability, ultimately achieving simultaneous excellence in specific capacitance, conductivity, and cycling stability.

[0050] Comparative Example 1, which did not undergo metal ion doping and sulfidation modification in step S2, lacked active sites for Ni-Co-La metal sulfide nanocrystals. Furthermore, due to the absence of melamine treatment, it lacked melamine-induced 3D porous structure support, resulting in severe interlayer stacking of MXene. The MXene surface groups were not optimized, and the electron transport path was singular. Therefore, its specific capacitance and conductivity were significantly lower than those of the Example. Moreover, without the structural support of metal sulfides during cycling, its stability decreased significantly.

[0051] Comparative Example 2 lacks a nitrogen-doped carbon layer formed by polydopamine carbonization, which neither enables the construction of a three-dimensional conductive network to improve electron transport efficiency nor strengthens the interfacial bonding force through the carbon layer. As a result, the conductivity and cycle stability are weaker than those of the Example. The insufficient synergistic effect between the active component and MXene also limits the improvement of specific capacitance.

[0052] Comparative Example 3 did not undergo step S4, so the MXene interlayer stacking problem was not effectively suppressed, and the ion transport channels were blocked, resulting in insufficient specific capacitance, conductivity and cycling stability.

[0053] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a fluorinated modified MXene-based conductive composite material, characterized in that, Includes the following steps: Step 1: Fluoride etching of Ti3AlC2 using concentrated hydrochloric acid and lithium fluoride to obtain fluorinated MXene powder; Step 2: Under hydrothermal conditions, Ni from nickel source, cobalt source, and lanthanum source... 2+ Co 2+ La 3+ S is uniformly deposited on the surface of fluorinated MXene powder and reacted with sulfur powder through a disproportionation reaction. 2- The reaction, combined with ammonium fluoride to optimize surface groups, yielded fluorinated modified MXene powder; Step 3: Using dopamine hydrochloride as a nitrogen source, nitrogen is doped into fluorinated modified MXene powder, and then heat-treated to obtain nitrogen-doped fluorinated modified MXene powder. Step 4: Under hydrothermal conditions, Zn 2+ In 3+ With S 2- In-situ reaction generates ZnIn2S4, which is anchored on nitrogen-doped fluorinated modified MXene powder. Simultaneously, graphene oxide is inserted into the interlayer of nitrogen-doped fluorinated modified MXene powder to obtain a fluorinated modified MXene-based conductive composite material.

2. The method for preparing a fluorinated modified MXene-based conductive composite material according to claim 1, characterized in that, The specific preparation process of the fluorinated modified MXene-based conductive composite material described in step four is as follows: Nitrogen-doped fluorinated modified MXene powder, anhydrous ethanol, and deionized water were added to a high-pressure reactor and ultrasonically dispersed for 20-30 minutes. Zinc salt solution and indium salt solution were added and stirred for 40-50 minutes. Thioacetamide and graphene oxide were then added and stirred for 20-30 minutes. Air was purged with nitrogen and the mixture was reacted at 120-130°C for 2-3 hours. The mixture was then naturally cooled to room temperature, washed, and dried to obtain the fluorinated modified MXene-based conductive composite material.

3. The method for preparing a fluorinated modified MXene-based conductive composite material according to claim 2, characterized in that, The ratio of nitrogen-doped fluorinated modified MXene powder, anhydrous ethanol, deionized water, zinc salt solution, indium salt solution, thioacetamide, and graphene oxide is 1-1.5 g: 1-1.4 L: 1-1.4 L: 2-3 mmol: 4-6 mmol: 12-16 mmol: 0.2-0.4 g; The zinc salt solution is one of zinc chloride and zinc acetate; The indium salt solution is one of indium iodide and indium chloride.

4. The method for preparing a fluorinated modified MXene-based conductive composite material according to claim 1, characterized in that, The specific preparation process of the nitrogen-doped fluorinated modified MXene powder is as follows: Fluorinated MXene powder and deionized water were added to a reaction vessel and stirred until homogeneous. The pH of the solution was adjusted to 8.5 and stirred for 30-40 min. A dopamine hydrochloride solution with a concentration of 8 g / L was slowly added dropwise. The mixture was stirred under dark conditions, centrifuged, washed, and dried. The temperature was increased to 400-450℃ at a rate of 5℃ / min and heated for 2-3 h under a nitrogen atmosphere to obtain nitrogen-doped fluorinated MXene powder.

5. The method for preparing a fluorinated modified MXene-based conductive composite material according to claim 4, characterized in that, The ratio of fluorinated modified MXene powder, deionized water, and dopamine hydrochloride solution is 2.2-3.2g: 5-6L: 5-6L.

6. The method for preparing a fluorinated modified MXene-based conductive composite material according to claim 1, characterized in that, The specific preparation process of the fluorinated modified MXene powder is as follows: A 50 vol% aqueous ethanol solution, nickel chloride hexahydrate, lanthanum nitrate, cobalt salt, urea, ammonium fluoride, sulfur powder, and melamine were added to a reaction vessel and stirred until completely dissolved. Then, fluorinated MXene powder was added to the reaction vessel and ultrasonically dispersed for 30-40 minutes. The mixture was then hydrothermally reacted at 120-130℃ for 4-5 hours. After washing and drying, fluorinated modified MXene powder was obtained.

7. The method for preparing a fluorinated modified MXene-based conductive composite material according to claim 6, characterized in that, The ratio of the following components to be used is 400-500 mL: 1.2-1.8 g: 0.05-0.07 g: 2.4-3.2 g: 4.5-5.5 g: 0.9-1.3 g: 3-5 g: 0.5-0.7 g: 3.0-4.0 g; The cobalt salt is one of cobalt chloride hexahydrate and cobalt nitrate.

8. The method for preparing a fluorinated modified MXene-based conductive composite material according to claim 1, characterized in that, The specific preparation process of the fluorinated MXene powder is as follows: Pure water, concentrated hydrochloric acid, and lithium fluoride were added sequentially to the reactor and stirred for 15-25 minutes. Ti3AlC2 was added in five portions, and the mixture was stirred at 55-65℃ for 24-26 hours. The mixture was then sonicated, the pH was adjusted to 7, and the mixture was dried to obtain fluorinated MXene powder.

9. The method for preparing a fluorinated modified MXene-based conductive composite material according to claim 8, characterized in that, The ratio of pure water, concentrated hydrochloric acid, lithium fluoride, and Ti3AlC2 is 100-150mL:100-150mL:10-15g:10g.

10. A fluorinated modified MXene-based conductive composite material, characterized in that, The fluorinated modified MXene-based conductive composite material was prepared by any one of claims 1-9.

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