Preparation method of melamine modified MXene material and application thereof

Abstract

This invention discloses a method for preparing and applying melamine-modified MXene materials, belonging to the field of nanomaterials. The preparation method includes the following steps: First, Ti3C2T is prepared by selective etching and layering in a LiF / HCl mixed solution. x Nanosheets. Next, melamine and Ti3C2T are added. x The suspension was mixed and stirred to promote the formation of hydrogen bonds between the end groups. After stirring, it was allowed to stand for 12 hours to further stabilize the formed hydrogen bonds. Finally, the final product Ti3C2T was obtained through washing, freeze-drying, and other processes. x / MA. The Ti3C2T x In the melamine / MA material, the optimal melamine content is 2.1 wt%, and its triazine ring structure optimizes lithium-ion transport. The melamine-modified MXene material of this invention features a large specific surface area, high lithium storage capacity, excellent lithium-ion diffusion ability, numerous lithium storage sites, and good rate performance.

Description

Technical Field

[0001] The invention belongs to the field of nanomaterials, specifically involving a method for preparing and applying melamine-modified MXene materials. Background Technology

[0002] With surging global energy demand and increasingly constrained fossil fuel resources, the scale of renewable energy installations, primarily solar and wind power, continues to expand. However, their geographical dependence and intermittent nature create an urgent need for efficient energy storage systems. Against this backdrop, lithium-ion batteries, due to their high energy density, long cycle life, and environmentally friendly characteristics, have become the core technology for energy storage in electric vehicles and smart electronic products. In lithium-ion batteries, the anode material, as a crucial component, directly affects battery performance. Therefore, developing novel lithium-ion battery anode materials with superior performance is of paramount importance.

[0003] Since the discovery of novel graphene-like two-dimensional transition metal carbide / nitride (MXene) materials in 2001, more than 70 different MAX phases have been reported, and Ti3C2T x Due to its excellent electrical conductivity and hydrophilicity, abundant active sites, and superior mechanical properties, MXene has gradually become the most widely used material, used in applications such as alkali metal batteries, metal-air batteries, and capacitors. The main step in its preparation is the selective etching of the Al layer in the Ti3AlC2 phase, and this etching process inevitably introduces various functional groups. The stacking of nanosheets and the introduction of undesirable functional groups (F, OH) all reduce the efficiency of Ti3C2T... x The technical challenge of reducing the lithium storage sites and thus lowering the lithium ion diffusion rate, resulting in a lower actual capacity, urgently needs to be addressed. Summary of the Invention

[0004] This invention aims to overcome the limitations of existing Ti3C2T technologies. x To address the technical shortcomings of lithium-ion batteries, a method is provided for preparing melamine (MA) modified MXene materials with large specific surface area, high lithium storage capacity, excellent rate performance, and strong lithium-ion diffusion ability.

[0005] This invention also provides a MA-modified two-dimensional nano-Ti3C2T x Material (Ti3C2T) x Applications of / MA in electrochemistry.

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows:

[0007] Ti3C2T x The preparation method of / MA material includes the following steps in sequence:

[0008] I. Ti3C2Tx Preparation of nanosheet suspension

[0009] 1.1 Add LiF to HCl and stir until completely dissolved; then add Ti3AlC2 powder to the solution;

[0010] 1.2 Transfer the mixed solution obtained in step 1.1 to a constant temperature oil bath for reaction. After the reaction is complete, centrifuge and wash the solid residue until the pH of the supernatant is close to neutral.

[0011] 1.3 The bottom reaction product obtained in step 1.2 was ultrasonicated in an ice bath under inert gas protection; after centrifugation and ultrasonication, the supernatant was collected to obtain Ti3C2T. x Nanosheet suspension;

[0012] II. Ti3C2T x / MA preparation

[0013] 2.1 Add MA powder to deionized water and ultrasonically stir until completely dissolved; then slowly add it dropwise to the Ti3C2T mixture described in step 1.3 under magnetic stirring. x In nanosheet suspension; the MA and Ti3C2T x The mass ratio is 1 to 12:10;

[0014] 2.2 After stirring, let the solution obtained in step 2.1 stand, then centrifuge and wash until the pH of the filtrate is close to neutral;

[0015] 2.3 The centrifuged product obtained in step 2.2 was freeze-dried to obtain the target product Ti3C2T. x / MA material.

[0016] Furthermore, the MA is bonded to Ti3C2T via hydrogen bonds. x The functional groups such as -OH and -F on the surface are connected, and self-assembly results in a higher specific surface area.

[0017] Further, in step 1.1, 0.998g of LiF is added to 10mL of concentrated HCl and stirred until completely dissolved; then, 1g of Ti3AlC2 powder is added to the solution.

[0018] Further, in step 1.2, the mixed solution obtained in step 1.1 is transferred to a 36°C constant temperature oil bath and reacted for 24 hours to etch and remove the Al layer. After the reaction is complete, the solid residue is washed with deionized water by centrifugation until the pH of the supernatant is close to neutral.

[0019] Further, in step 2.1, MA powder is added to 25 mL of deionized water and ultrasonically stirred for 5 min to completely dissolve it; then, under magnetic stirring, it is slowly added dropwise to the Ti3C2T... xIn nanosheet suspension; the MA and Ti3C2T x The mass ratio is 1 to 12:10, preferably 2:10; in step 2.2, after stirring, the solution obtained in step 2.1 is allowed to stand for 12 hours, and then washed multiple times by centrifugation with deionized water to remove excess MA in the solution until the pH of the filtrate is close to neutral.

[0020] Furthermore, in step 2.3, the optimal content of MA in the Ti3C2Tx / MA material is 2.1 wt%, and its BET specific surface area is 76.4 m². 2 g -1 ;

[0021] The electrochemical applications of the Ti3C2Tx / MA material prepared by the above method with hydrogen-bonded network include using 1-methyl-2-pyrrolidone as a solvent to prepare Ti3C2T... x The MA material, conductive agent, and binder are mixed, ground, and then coated onto copper foil, followed by vacuum drying. The electrode sheets are assembled into a button half-cell in an argon-filled glove box. Lithium foil is used as the counter electrode, Celgard 2400 is used as the separator, and LiPF6 is dissolved in a mixture of ethylene carbonate, dimethyl carbonate, and diethyl carbonate as the electrolyte.

[0022] Furthermore, the conductive agent is acetylene black; the binder is polyvinylidene fluoride; the conductive agent is acetylene black; the binder is polyvinylidene fluoride; the mass ratio of the MA-modified MXene material, the conductive agent, and the binder is 8:1:1.

[0023] Furthermore, the volume ratio of ethylene carbonate, dimethyl carbonate, and diethyl carbonate is 1:1:1.

[0024] Compared with the prior art, the present invention has the following beneficial effects: The present invention prepares Ti3C2T x / MA material, MA and Ti3C2T x The functional groups on the surface are connected by a hydrogen bond network, which avoids the formation of Ti3C2T x The self-stacking of nanosheets increases the specific surface area of ​​the material.

[0025] This invention prepares Ti3C2T x / MA and Ti3C2T in MA materials xThe hydrogen bonds formed by the functional groups on the surface not only prevent the self-stacking of nanosheets, but more importantly, MA also acts as a "shielder" against the -OH end groups, hindering lithium-ion transport. Specifically, during lithium storage, the high electron cloud density of the triazine ring in MA pulls lithium ions around the -OH end groups closer to the unsaturated nitrogen and away from the -OH groups, thus preventing the -OH end groups from obstructing lithium-ion transport. This invention utilizes the synergistic effect of optimizing the specific surface area of ​​MXene through the hydrogen bond network of MA and shielding the -OH end groups, significantly improving the lithium-ion transport and diffusion capabilities.

[0026] MA is an organic anode material, and its triazine rings can serve as lithium storage sites. When the MA content is low, interfacial modification exists, and the adsorption of lithium by the triazine rings alters the lithium-ion transport pathway. When pure MA is used or the MA content exceeds a certain threshold, it becomes a common lithium storage material. See Examples 2-4 to verify that excessive MA leads to performance degradation. Figure 10 Example 2 shows that excessive MA (5.1 wt%) leads to performance degradation. Example 4 is an exploration of the upper limit of the feed ratio; only by using a specific amount of MA can it form an interface modification function in space, thereby improving the lithium storage characteristics of titanium carbide. In the present invention, Ti3C2T x After MA modification, the specific surface area is 76.4 m². 2 g-1) was significantly higher than that of the comparative sample (27.6m). 2 g -1 ), and the cycle capacity (387.7 mAh g) -1 Exceeding the theoretical capacity of commercially available graphite anodes (372 mAh g) -1 The significant improvement in lithium-ion diffusion coefficient was verified through testing (see [link]). Figure 13 This demonstrates the role of hydrogen bond networks in improving kinetics.

[0027] MA-modified Ti3C2T prepared in this invention x Due to its unique triazine ring structure, the material *MA* not only "shields" the -OH end groups but also provides superior lithium-ion storage sites. In this invention, *MA* forms a stable structure through physical adsorption (not chemical bonding), avoiding MXene sheet stacking and simultaneously shielding the -OH groups from lithium. + Obstacles (see) Figures 7-8 (Redshift comparison).

[0028] This invention prepares MA-modified Ti3C2T x The process is simple; the target product can be obtained simply by stirring, without complex processes such as annealing, which can save costs and facilitate large-scale production.

[0029] The Ti3C2T prepared in this inventionx The optimal MA content in / MA is 2.1 wt%, and its triazine ring structure optimizes lithium-ion transport. Based on the unique triazine ring structure of MA, it provides better lithium storage sites and lowers the ion diffusion barrier, effectively improving lithium storage capacity. In this invention, MA is grafted with Ti3C2T via hydrogen bonding. x This is a strategy that balances functionalization and intrinsic properties, expanding its application potential in composite materials, energy storage, and other fields. The Ti3C2T prepared in this invention... x / MA materials have a large specific surface area, possessing advantages such as rapid lithium-ion diffusion, high lithium storage capacity, and good rate performance. Furthermore, this invention, Ti3C2T... x / MA materials are easy to prepare, and the amount of MA modification is controllable, making them suitable for large-scale applications. Attached Figure Description

[0030] The present invention will now be described in detail through specific embodiments. These embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art. As used throughout the specification and claims, the terms "comprising" or "including" are open-ended and are interpreted as "comprising but not limited to". The following description is a preferred embodiment for carrying out the invention; however, this description is intended to illustrate the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the invention is determined by the appended claims. Unless otherwise specified, all reagents and materials used in the present invention are commercially available.

[0031] Figure 1 The Ti3C2T in Example 1 x It interacts with MA to form Ti3C2T x / MA optical image;

[0032] Figure 2 The Ti3C2T in Example 1 x / MA、Ti3C2T x Zeta potential plot of MA;

[0033] Figure 3 Example 1, Comparative Example 1, and XRD patterns of MA;

[0034] Figure 4 Infrared spectra of Example 1 and Comparative Example 1;

[0035] Figure 5 XPS O1s plots of Example 1 and Comparative Example 1;

[0036] Figure 6 MA-modified Ti3C2T prepared in Example 1 xScanning electron microscope images of the material and its elemental mapping diagrams for Ti, C, O, F and N;

[0037] Figure 7 In Example 1, Ti3C2T x XPS Nls plot for / MA;

[0038] Figure 8 Infrared spectra of Comparative Example 1 at 0.01V and 3V;

[0039] Figure 9 Infrared spectra of Example 1 at 0.01V and 3V;

[0040] Figure 10 Comparison of cyclic performance between the examples and comparative examples;

[0041] Figure 11 Comparison of cycling tests of Example 1 and Comparative Example 1 at different temperatures;

[0042] Figure 12 Constant current intermittent titration curves of Example 1 and Comparative Example 1;

[0043] Figure 13 Comparison of lithium-ion diffusion coefficients between Example 1 and Comparative Example 1;

[0044] Figure 14 Electrochemical impedance spectroscopy of Example 1 and Comparative Example 1. Detailed Implementation

[0045] The technical solution of the present invention is illustrated by the following embodiments, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or parameter adjustments based on the technical features of the present invention fall within the scope of protection of this patent.

[0046] Example 1:

[0047] First, 0.998 g of LiF was added to 10 mL of concentrated HCl (12 M) and stirred until completely dissolved. Then, 1 g of Ti3AlC2 powder was slowly added to the solution, and the mixture was transferred to a 36°C oil bath for 24 h to etch away the Al layer. After the reaction was complete, the solid residue was repeatedly washed with deionized water by centrifugation (3500 rpm, 5 min) until the pH of the supernatant was close to neutral. Then, the bottom reaction product was redispersed in 20 mL of deionized water and sonicated in an ice bath for 1 h under inert gas protection. Finally, the sonicated solution was centrifuged for 1 h (3500 rpm), and the supernatant was collected to obtain Ti3C2T. x Nanosheet suspension.

[0048] Weigh 10 mg of MA powder and add it to 25 mL of deionized water. Sonicate for 5 minutes to dissolve completely. Then, under magnetic stirring, slowly add it dropwise to 25 mL of the previously prepared 2 mg / mL solution. -1 Ti3C2T x The solution was added. After the addition was complete, an inert gas was introduced for protection, and stirring continued for 24 hours. The stirred solution was allowed to stand for 12 hours, and then washed three times with deionized water (3500 rpm, 5 min) to remove excess MA from the solution until the pH of the filtrate was close to neutral. Finally, the centrifuged product was freeze-dried to obtain the final Ti3C2T. x / MA material. MA in Ti3C2T x The content of / MA in the material is 2.1 wt%.

[0049] 1. Electrochemical performance testing

[0050] Using 1-methyl-2-pyrrolidone as solvent, the active material, conductive agent acetylene black, and binder polyvinylidene fluoride were mixed in a mass ratio of 8:1:1, thoroughly ground, and then coated onto copper foil. The mixture was then dried in vacuum ovens at 60℃ and 120℃ for 12 hours, respectively. The final active material loading on the electrode sheet was maintained at approximately 0.8–1.2 mg. The cut electrode sheets were assembled into CR-2025 button half-cells in an argon-filled glove box, with lithium foil as the counter electrode, Celgard 2400 as the separator, and 1M LiPF6 dissolved in a 1:1:1 volume ratio of ethylene carbonate / dimethyl carbonate / diethyl carbonate (EC / EMC / DEC) as the electrolyte. All constant current charge-discharge tests were recorded using a LANDCT2001A test system within a voltage range of 0.01–3.00 V. Electrochemical impedance spectroscopy (EIS) was collected on a CHI-760E electrochemical workstation, with the measurement frequency range from 100 kHz to 10 mHz. The galvanostatic intermittent titration technique was performed by applying 0.05 Ag to the LAND test system. -1 The pulse current was applied for 20 minutes, and then the circuit was left to stand for 2 hours in an open circuit state before testing.

[0051] See Figure 1 As shown, Figure 1 The Ti3C2T is presented intuitively. x Optical images of the interaction between the MA and Ti3C2T before the addition of the MA. x Electrostatic repulsion between the nanosheets themselves leads to uniform dispersion of the solution, forming a colloidal dispersion. Upon the addition of MA, significant stratification occurs: the upper layer is a transparent solution, and the lower layer is a self-assembled precipitate. This can be attributed to the interaction between MA and Ti3C2T. x The nanosheets generated hydrogen bonding forces, Ti3C2T xThe terminal functional groups of MA interact with nitrogen on the MA molecule, inducing the self-assembly of two-dimensional sheets, which then lead to sedimentation.

[0052] See Figure 2 As shown, Figure 2 Due to the presence of highly electronegative functional groups on its surface, Ti3C2T x The Zeta potential is -39.6 mV. MA grafted onto Ti3C2T x The surface of nanosheets leads to Ti3C2T x The electrostatic repulsion between the nanosheets weakens (from -39.6 mV to -23.6 mV). When the weakened electrostatic repulsion is insufficient to overcome its high surface energy, Ti3C2T... x The nanosheets spontaneously assemble to reduce the overall surface energy of the material. As a result, a large amount of precipitate can be observed at the bottom of the sample vial.

[0053] See Figure 3 As shown, Figure 3 The XRD patterns of Example 1, Comparative Example 1, and MA are shown. Compared with Comparative Example 1, the (002) characteristic diffraction peak position of Example 1 is slightly forward, and the interlayer spacing is increased after MA modification. The increased interlayer spacing can improve the performance of Ti3C2T. x The electrolyte accessibility of nanosheets promotes Li + The migration of these molecules enables excellent lithium storage performance.

[0054] See Figure 4 As shown, Figure 4 As shown, the absorption peaks of -OH and C=O in Example 1 show a significant red shift compared to Comparative Example 1, which is due to the formation of hydrogen bonds. (O1s XPS spectrum) Figure 5 The shifts in -OH and C=O further prove the relationship between MA and Ti3C2T. x Hydrogen bonds are present. Furthermore... Figure 6 The elemental distribution in the sample of Example 1 is provided. The N element is evenly distributed with Ti, C, O, and F, further demonstrating that MA was successfully modified in the Ti3C2T sample of Example 1. x In the material. XPS spectrum of nitrogen element in Example 1 ( Figure 7 This also confirms the phenomenon.

[0055] Figure 8 and Figure 9 The infrared spectra of Example 1 and Comparative Example 1 at 0.01V (lithium-ion insertion) and 3V (lithium-ion extraction) are shown. In Comparative Example 1, the insertion of lithium ions causes a red shift in the -OH group, while in Example 1, no significant shift in the -OH group occurs. This confirms that MA "shields" the -OH group and the lithium ion. + Interactions between them.

[0056] Next, we conducted a constant current charge-discharge test on the battery, with a current density of 0.1 Ag. -1 .like Figure 10 As shown, MA and Ti3C2T x The optimal ratio of MA to Ti3C2T is 2:10 (MA content 2.1 wt%, Example 1). x A feed ratio of 12:10 (Example 4) was used as an exploration case to determine the upper limit of feed ratio, verifying that excessive MA leads to performance degradation. Meanwhile, the lithium storage capacity of Example 1 was significantly increased compared to Comparative Example 1, and its cycle performance was excellent. After 100 cycles, the discharge capacity of Example 1 reached 387.7 mAh g. -1 The comparative example 1 has only 198.5 mAh g. -1 .

[0057] To verify Ti3C2T x To explore the potential of / MA electrode materials in practical applications, we conducted constant current charge-discharge tests within a temperature range of 50 to -20°C. Figure 11 The results showed that 0.1 Ag -1 The discharge capacities of Example 1 at current densities of 417.7, 388.6, 338.3, 310.8, 287.2, 245.0, 194.1, and 136.5 mAh g at 50, 40, 30, 20, 10, 0, -10, and -20 °C were respectively. -1 Furthermore, the discharge capacity values ​​within each temperature gradient are higher than those of Comparative Example 1. This excellent capacity retention over a wide temperature range demonstrates that the invention possesses good electrochemical stability and reversibility, making it more suitable for applications under extreme conditions.

[0058] Next, we conducted an in-depth study of its lithium storage kinetics. For example... Figure 12 As shown, the titration curve was obtained by applying a pulsed current to the electrode for 20 minutes followed by a relaxation time of 2 hours. The diffusion coefficient extracted from the GITT curve is shown in [the figure]. Figure 13 In the middle, Ti3C2T under different voltages x Both / MA have a relatively large ion diffusion coefficient, indicating that Ti3C2T x / MA has better Li + The diffusion kinetics capability is due to the modification of MA. Figure 14 Nyquist curves are shown in the frequency range of 100 kHz to 10 MHz, where the impedance values ​​of the examples are lower than those of Comparative Example 1. In summary, this MA modification strategy improves the electrochemical performance of Ti3C2T. x Its charge transfer capability.

[0059] Example 2:

[0060] First, 0.998 g of LiF was added to 10 mL of concentrated HCl (12 M) and stirred until completely dissolved. Then, 1 g of Ti3AlC2 powder was slowly added to the solution, and the mixture was transferred to a 36°C oil bath for 24 h to etch away the Al layer. After the reaction was complete, the solid residue was repeatedly washed with deionized water by centrifugation (3500 rpm, 5 min) until the pH of the supernatant was close to neutral. Then, the bottom reaction product was redispersed in 20 mL of deionized water and sonicated in an ice bath for 1 h under inert gas protection. Finally, the sonicated solution was centrifuged for 1 h (3500 rpm), and the supernatant was collected to obtain Ti3C2T. x Nanosheet suspension.

[0061] Weigh 30 mg of MA powder and add it to 25 mL of deionized water. Sonicate for 5 minutes to dissolve completely. Then, under magnetic stirring, slowly add it dropwise to 25 mL of the previously prepared 2 mg / mL solution. -1 Ti3C2T x The solution was added. After the addition was complete, an inert gas was introduced for protection, and stirring continued for 24 hours. The stirred solution was allowed to stand for 12 hours, and then washed three times with deionized water (3500 rpm, 5 min) to remove excess MA from the solution until the pH of the filtrate was close to neutral. Finally, the centrifuged product was freeze-dried to obtain the final Ti3C2T. x / MA material. Among them, MA is used in Ti3C2T x The content of / MA in the material is 5.1 wt%.

[0062] The obtained Ti3C2T x The active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a mass ratio of 8:1:1, thoroughly ground, and then coated onto copper foil. The mixtures were then dried in vacuum ovens at 60℃ and 120℃ for 12 hours, respectively. The final active material loading on the electrode sheets was maintained at approximately 1–1.2 mg. The cut electrode sheets were assembled into CR-2025 button half-cells in an argon-filled glove box, with lithium foil as the counter electrode, Celgard 2400 as the separator, and 1M LiPF6 dissolved in a 1:1:1 volume ratio of ethylene carbonate / dimethyl carbonate / diethyl carbonate (EC / EMC / DEC) as the electrolyte. All galvanostatic charge-discharge (GCD) tests were recorded using a LANDCT2001A testing system within a voltage range of 0.01–3.00 V.

[0063] Example 3:

[0064] First, 0.998 g of LiF was added to 10 mL of concentrated HCl (12 M) and stirred until completely dissolved. Then, 1 g of Ti3AlC2 powder was slowly added to the solution, and the mixture was transferred to a 36°C oil bath for 24 h to etch away the Al layer. After the reaction was complete, the solid residue was repeatedly washed with deionized water by centrifugation (3500 rpm, 5 min) until the pH of the supernatant was close to neutral. Then, the bottom reaction product was redispersed in 20 mL of deionized water and sonicated in an ice bath for 1 h under inert gas protection. Finally, the sonicated solution was centrifuged for 1 h (3500 rpm), and the supernatant was collected to obtain Ti3C2T. x Nanosheet suspension.

[0065] Weigh 15 mg of MA powder and add it to 25 mL of deionized water. Sonicate for 5 minutes to dissolve completely. Then, under magnetic stirring, slowly add it dropwise to 25 mL of the previously prepared 2 mg / mL solution. -1 Ti3C2T x The solution was added. After the addition was complete, an inert gas was introduced for protection, and stirring continued for 24 hours. The stirred solution was allowed to stand for 12 hours, and then washed three times with deionized water (3500 rpm, 5 min) to remove excess MA from the solution until the pH of the filtrate was close to neutral. Finally, the centrifuged product was freeze-dried to obtain the final Ti3C2T. x / MA material.

[0066] The obtained Ti3C2T x The active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a mass ratio of 8:1:1, thoroughly ground, and then coated onto copper foil. The mixtures were then dried in vacuum ovens at 60℃ and 120℃ for 12 hours, respectively. The final active material loading on the electrode sheets was maintained at approximately 1–1.2 mg. The cut electrode sheets were assembled into CR-2025 button half-cells in an argon-filled glove box, with lithium foil as the counter electrode, Celgard 2400 as the separator, and 1M LiPF6 dissolved in a 1:1:1 volume ratio of ethylene carbonate / dimethyl carbonate / diethyl carbonate (EC / EMC / DEC) as the electrolyte. All galvanostatic charge-discharge (GCD) tests were recorded using a LANDCT2001A testing system within a voltage range of 0.01–3.00 V.

[0067] Example 4:

[0068] First, 0.998 g of LiF was added to 10 mL of concentrated HCl (12 M) and stirred until completely dissolved. Then, 1 g of Ti3AlC2 powder was slowly added to the solution, and the mixture was transferred to a 36°C oil bath for 24 h to etch away the Al layer. After the reaction was complete, the solid residue was repeatedly washed with deionized water by centrifugation (3500 rpm, 5 min) until the pH of the supernatant was close to neutral. Then, the bottom reaction product was redispersed in 20 mL of deionized water and sonicated in an ice bath for 1 h under inert gas protection. Finally, the sonicated solution was centrifuged for 1 h (3500 rpm), and the supernatant was collected to obtain Ti3C2T. x Nanosheet suspension.

[0069] Weigh 60 mg of MA powder and add it to 25 mL of deionized water. Sonicate for 5 minutes to dissolve completely. Then, under magnetic stirring, slowly add it dropwise to 25 mL of the previously prepared 2 mg / mL solution. -1 Ti3C2T x The solution was added. After the addition was complete, an inert gas was introduced for protection, and stirring continued for 24 hours. The stirred solution was allowed to stand for 12 hours, and then washed three times with deionized water (3500 rpm, 5 min) to remove excess MA from the solution until the pH of the filtrate was close to neutral. Finally, the centrifuged product was freeze-dried to obtain the final Ti3C2T. x / MA material.

[0070] The obtained Ti3C2T x The active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a mass ratio of 8:1:1, thoroughly ground, and then coated onto copper foil. The mixtures were then dried in vacuum ovens at 60℃ and 120℃ for 12 hours, respectively. The final active material loading on the electrode sheets was maintained at approximately 1–1.2 mg. The cut electrode sheets were assembled into CR-2025 button half-cells in an argon-filled glove box, with lithium foil as the counter electrode, Celgard 2400 as the separator, and 1M LiPF6 dissolved in a 1:1:1 volume ratio of ethylene carbonate / dimethyl carbonate / diethyl carbonate (EC / EMC / DEC) as the electrolyte. All galvanostatic charge-discharge (GCD) tests were recorded using a LANDCT2001A testing system within a voltage range of 0.01–3.00 V.

[0071] Example 5:

[0072] First, 0.998 g of LiF was added to 10 mL of concentrated HCl (12 M) and stirred until completely dissolved. Then, 1 g of Ti3AlC2 powder was slowly added to the solution, and the mixture was transferred to a 36°C oil bath for 24 h to etch away the Al layer. After the reaction was complete, the solid residue was repeatedly washed with deionized water by centrifugation (3500 rpm, 5 min) until the pH of the supernatant was close to neutral. Then, the bottom reaction product was redispersed in 20 mL of deionized water and sonicated in an ice bath for 1 h under inert gas protection. Finally, the sonicated solution was centrifuged for 1 h (3500 rpm), and the supernatant was collected to obtain Ti3C2T. x Nanosheet suspension.

[0073] Weigh 5 mg of MA powder and add it to 25 mL of deionized water. Sonicate for 5 min to dissolve completely. Then, under magnetic stirring, slowly add it dropwise to 25 mL of the 2 mg / mL solution prepared above. -1 Ti3C2T x The solution was added. After the addition was complete, an inert gas was introduced for protection, and stirring continued for 24 hours. The stirred solution was allowed to stand for 12 hours, and then washed three times with deionized water (3500 rpm, 5 min) to remove excess MA from the solution until the pH of the filtrate was close to neutral. Finally, the centrifuged product was freeze-dried to obtain the final Ti3C2T. x / MA material.

[0074] The obtained Ti3C2T x The active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a mass ratio of 8:1:1, thoroughly ground, and then coated onto copper foil. The mixtures were then dried in vacuum ovens at 60℃ and 120℃ for 12 hours, respectively. The final active material loading on the electrode sheets was maintained at approximately 1–1.2 mg. The cut electrode sheets were assembled into CR-2025 button half-cells in an argon-filled glove box, with lithium foil as the counter electrode, Celgard 2400 as the separator, and 1M LiPF6 dissolved in a 1:1:1 volume ratio of ethylene carbonate / dimethyl carbonate / diethyl carbonate (EC / EMC / DEC) as the electrolyte. All galvanostatic charge-discharge (GCD) tests were recorded using a LANDCT2001A testing system within a voltage range of 0.01–3.00 V.

[0075] Comparative Example 1:

[0076] First, 0.998 g of LiF was added to 10 mL of concentrated HCl (12 M) and stirred until completely dissolved. Then, 1 g of Ti3AlC2 powder was slowly added to the solution, and the mixture was transferred to a 36°C oil bath for 24 h to etch away the Al layer. After the reaction was complete, the solid residue was repeatedly washed with deionized water by centrifugation (3500 rpm, 5 min) until the pH of the supernatant was close to neutral. Then, the bottom reaction product was redispersed in 20 mL of deionized water and sonicated in an ice bath for 1 h under inert gas protection. The sonicated solution was centrifuged for 1 h (3500 rpm), and the supernatant was collected to obtain Ti3C2T. x Nanosheet suspension. Finally, the obtained supernatant product was freeze-dried to obtain the final Ti3C2T. x Material.

[0077] The obtained Ti3C2T x The active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a mass ratio of 8:1:1, thoroughly ground, and then coated onto copper foil. The mixtures were then dried in vacuum ovens at 60℃ and 120℃ for 12 hours, respectively. The final active material loading on the electrode sheets was approximately 1–1.2 mg. The cut electrode sheets were assembled into CR-2025 button half-cells in an argon-filled glove box, with lithium foil as the counter electrode, Celgard 2400 as the separator, and 1M LiPF6 dissolved in a 1:1:1 volume ratio of ethylene carbonate / dimethyl carbonate / diethyl carbonate (EC / EMC / DEC) as the electrolyte. All galvanostatic charge-discharge (GCD) tests were recorded using a LANDCT2001A testing system within a voltage range of 0.01–3.00 V.

[0078] Comparative Example 2:

[0079] First, 0.998 g of LiF was added to 10 mL of concentrated HCl (12 M) and stirred until completely dissolved. Then, 1 g of Ti3AlC2 powder was slowly added to the solution, and the mixture was transferred to a 36°C oil bath for 24 h to etch away the Al layer. After the reaction was complete, the solid residue was repeatedly washed with deionized water by centrifugation (3500 rpm, 5 min) until the pH of the supernatant was close to neutral. Then, the bottom reaction product was redispersed in 20 mL of deionized water and sonicated in an ice bath for 1 h under inert gas protection. The sonicated solution was centrifuged for 1 h (3500 rpm), and the supernatant was collected to obtain Ti3C2T. x Nanosheet suspension. Then, the obtained supernatant product was freeze-dried to obtain Ti3C2T. x Materials. Finally, Ti3C2T xThe material was calcined in a tube furnace at 300°C for 3 hours with Ar as the protective gas to obtain the final product.

[0080] The obtained Ti3C2T x The active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a mass ratio of 8:1:1, thoroughly ground, and then coated onto copper foil. The mixtures were then dried in vacuum ovens at 60℃ and 120℃ for 12 hours, respectively. The final active material loading on the electrode sheets was approximately 1–1.2 mg. The cut electrode sheets were assembled into CR-2025 button half-cells in an argon-filled glove box, with lithium foil as the counter electrode, Celgard 2400 as the separator, and 1M LiPF6 dissolved in a 1:1:1 volume ratio of ethylene carbonate / dimethyl carbonate / diethyl carbonate (EC / EMC / DEC) as the electrolyte. All galvanostatic charge-discharge (GCD) tests were recorded using a LANDCT2001A testing system within a voltage range of 0.01–3.00 V.

[0081] The above description is merely a specific embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent transformations made using the present invention, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing melamine-modified MXene material, characterized by comprising the following steps in sequence: I. Ti3C2T x Preparation of nanosheet suspension 1.1 Add LiF to HCl and stir until completely dissolved; then add Ti3AlC2 powder to the solution; 1.2 Transfer the mixed solution obtained in step 1.1 to a constant temperature oil bath for reaction. After the reaction is complete, centrifuge and wash the solid residue until the pH of the supernatant is close to neutral. 1.3 The bottom reaction product obtained in step 1.2 was ultrasonicated in an ice bath under inert gas protection; after centrifugation and ultrasonication, the supernatant was collected to obtain Ti3C2T. x Nanosheet suspension; II. Ti3C2T x / MA preparation 2.1 Melamine powder was added to deionized water and ultrasonically stirred until completely dissolved; then, under magnetic stirring, it was slowly added dropwise to the Ti3C2T mixture described in step 1.

3. x In the nanosheet suspension; the melamine and Ti3C2T x The mass ratio is 1 to 12:10; 2.2 After stirring, let the solution obtained in step 2.1 stand, then centrifuge and wash until the pH of the filtrate is close to neutral; 2.3 The centrifuged product obtained in step 2.2 is freeze-dried to obtain the target product, melamine-modified MXene material; the content of melamine in the melamine-modified MXene material is 2.1 wt%.

2. The method for preparing melamine-modified MXene material according to claim 1, characterized in that: melamine binds to Ti3C2T via hydrogen bonds. x The -OH and -F functional groups on the surface connect and self-assemble to form a three-dimensional structure.

3. The method for preparing melamine-modified MXene material according to claim 2, characterized in that: In step 1.1, 0.998 g of LiF was added to 10 mL of concentrated HCl and stirred until completely dissolved; then, 1 g of Ti3AlC2 powder was added to the solution.

4. The method for preparing melamine-modified MXene material according to claim 3, characterized in that: In step 1.2, the mixed solution obtained in step 1.1 is transferred to a 36°C constant temperature oil bath and reacted for 24 h to etch away the Al layer. After the reaction is complete, the solid residue is washed with deionized water by centrifugation until the pH of the supernatant is close to neutral.

5. The method for preparing melamine-modified MXene material according to claim 4, characterized in that: In step 2.1, melamine powder is added to 25 mL of deionized water and ultrasonically stirred for 5 min to completely dissolve it; then, under magnetic stirring, it is slowly added dropwise to the Ti3C2T... x In the nanosheet suspension; in step 2.2, after stirring, the solution obtained in step 2.1 is allowed to stand for 12 h, and then washed multiple times by centrifugation with deionized water to remove excess melamine in the solution until the pH of the filtrate is close to neutral.

6. The electrochemical application of the product obtained by the preparation method of melamine-modified MXene material as described in any one of claims 1 to 5, characterized in that: Using 1-methyl-2-pyrrolidone as a solvent, melamine-modified MXene material, a conductive agent, and a binder were mixed, ground, and then coated onto copper foil, followed by vacuum drying. The electrode sheets were assembled into a button half-cell in an argon-filled glove box. Lithium foil served as the counter electrode, Celgard 2400 as the separator, and LiPF6 was dissolved in a mixture of ethylene carbonate, dimethyl carbonate, and diethyl carbonate as the electrolyte. Acetylene black was used as the conductive agent, and polyvinylidene fluoride was used as the binder. The mass ratio of the melamine-modified MXene material, the conductive agent, and the binder was 8:1:1, and the volume ratio of ethylene carbonate, dimethyl carbonate, and diethyl carbonate was 1:1:1.

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