Ti3c2-based composite material, preparation method and application thereof

Abstract

This application provides a Ti3C2-based composite material, characterized in that it comprises a Ti3C2 substrate material and nanoparticles loaded on the Ti3C2 substrate material; based on the mass of the Ti3C2-based composite material as 100%, the mass percentage of the Ti3C2 substrate material is 80%–96%, and the mass percentage of the nanoparticles is 4%–20%. This application also provides a method for preparing the Ti3C2-based composite material and its applications. The Ti3C2-based composite material of this application has uniform particle size, which can effectively suppress the collapse and recombination of the accordion-like plate-like structure of the Ti3C2 material, while providing a large number of active sites; moreover, the Ti3C2-based composite material maintains good morphology and high purity, and can still retain its initial morphology after hydrothermal reaction. The preparation method of this application is simple, easy to operate, and has a short experimental cycle.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to a Ti3C2-based composite material, its preparation method, and its application. Background Technology

[0002] The overuse of fossil fuels has led to numerous environmental pollution problems, such as global warming and atmospheric smog. The emergence of lithium-ion batteries has significantly improved the current energy shortage situation. Due to their long cycle life and high energy density, lithium-ion batteries are among the most competitive candidates for energy storage devices. Graphite, as a widely used commercial lithium-ion battery anode material, has a theoretical specific capacity of only 370 mA hg. -1 Its specific capacity is relatively low and cannot meet the current demand of the lithium-ion battery market.

[0003] Two-dimensional (2D) materials are crystalline materials with one or more atomic layers. MXenes are a new type of two-dimensional layered transition metal carbides or nitrides that have attracted increasing attention from researchers due to their unique "accordion" layered structure, good hydrophilicity, and adaptability to intercalation with different electrolyte ions. Among the many MXenes, Ti3C2 has been extensively studied as a negative electrode material for lithium-ion batteries. It can increase the capacity of lithium-ion batteries by introducing additional reaction sites through loading or surface functional group modification. Furthermore, the two-dimensional voids between its layers can provide diffusion channels for lithium ions, making two-dimensional materials a focus of attention in electrochemical energy storage and conversion. However, Ti3C2 materials have weak conductivity, small specific surface area, and tend to accumulate into sheets during charging and discharging, which greatly limits their electrochemical applications. Summary of the Invention

[0004] Based on this, embodiments of the present invention provide a Ti3C2-based composite material, its preparation method and application, aiming to solve the problems that greatly limit the application of its electrochemical performance due to the weak conductivity, small specific surface area and easy accumulation of Ti3C2 materials into sheets during charging and discharging.

[0005] To achieve the above objectives, in one aspect, embodiments of the present invention provide a Ti3C2-based composite material, comprising a Ti3C2 substrate material and nanoparticles loaded on the Ti3C2 substrate material; based on the mass of the Ti3C2-based composite material as 100%, the mass percentage of the Ti3C2 substrate material is 80% to 96%, and the mass percentage of the nanoparticles is 4% to 20%.

[0006] By controlling the mass ratio of Ti3C2 substrate material to nanoparticles, the collapse and recombination of the accordion-like sheet structure of Ti3C2 substrate material can be effectively suppressed. At the same time, a large number of active sites (such as active sites for lithium ion insertion and extraction) can be provided, so that the morphology of Ti3C2-based composite material is well maintained and the purity is high. It can still maintain the initial morphology after hydrothermal reaction, thereby effectively improving the electrochemical performance of Ti3C2 substrate material.

[0007] In a preferred embodiment, the nanoparticles are LiTiO2 nanoparticles or Na2Ti3O7 nanoparticles.

[0008] On the other hand, embodiments of the present invention also provide a method for preparing the Ti3C2-based composite material, comprising the following steps:

[0009] SO1. Add Ti3C2 powder to the first solution and stir until homogeneous to obtain a mixed solution; add 50mg to 200mg of Ti3C2 powder to every 30ml to 100ml of the first solution;

[0010] SO2, the mixture from step S01 is subjected to a hydrothermal reaction to obtain a reaction product; the reaction product is centrifuged, the precipitate is collected, washed, and dried to obtain a Ti3C2-based composite material; the hydrothermal reaction conditions are 75℃~185℃ for 2h~16h.

[0011] In a preferred embodiment, in step S01,

[0012] Depending on the actual application requirements, 50 mg of Ti3C2 powder can be added to every 30 ml of the first solution, or 150 mg of Ti3C2 powder to every 50 ml of the first solution, or 200 mg of Ti3C2 powder to every 100 ml of the first solution, or 50 mg of Ti3C2 powder to every 100 ml of the first solution, etc., preferably 100 mg of Ti3C2 powder to every 50 ml of the first solution. This effectively suppresses the collapse and recombination of the accordion-like sheet structure of the Ti3C2 substrate material, while providing a large number of active sites (such as active sites for lithium ion insertion and extraction), thus maintaining a good morphology of the Ti3C2-based composite material.

[0013] The Ti3C2 powder was prepared by the following method: the MAX precursor was added to the second solution for etching, then centrifuged, the precipitate was collected, washed, and dried to obtain Ti3C2 powder; 0.5g to 2g of MAX precursor was added to every 10ml to 40ml of the second solution.

[0014] Depending on the actual application requirements, 0.5g of MAX precursor can be added to every 10ml of the second solution, or 2g of MAX precursor to every 40ml of the second solution, or 2g of MAX precursor to every 30ml of the second solution, etc., preferably 1g of MAX precursor to every 20ml of the second solution. This ensures the formation of Ti3C2 powder. The MAX precursor is Ti3AlC2; the second solution is an HF solution, preferably a 40wt% HF solution. Using an HF solution, the process is mature and well-established, and it is easy to etch out the ideal layered Ti3C2 powder.

[0015] The etching temperature is 40℃~60℃ (it can be 40℃, 45℃, 50℃ or 60℃, etc., depending on the actual needs of use), preferably 50℃; the etching time is 36h.

[0016] The centrifugation rate is 2000 r / min. -1 ~9000r min -1 The preferred speed is 6000 rpm. -1 ~9000r min -1 The centrifugation time is 4 min to 6 min.

[0017] The washing process uses deionized water.

[0018] The drying process is vacuum drying.

[0019] The vacuum drying temperature is preferably 75℃~85℃ (it can be 75℃, 78℃, 80℃ or 85℃, etc., depending on the actual needs of use), and the vacuum drying time is preferably 10h~20h (it can be 10h, 12h, 15h, 18h or 20h, etc., depending on the actual needs of use).

[0020] The first solution is an aqueous solution of LiOH or an aqueous solution of NaOH.

[0021] The LiOH aqueous solution is 1 mol L -1 The LiOH aqueous solution; the NaOH aqueous solution is 1 mol L -1 NaOH aqueous solution.

[0022] The stirring is magnetic stirring.

[0023] In a preferred embodiment, in step S02,

[0024] The hydrothermal reaction conditions are 100℃~165℃ (which can be 100℃, 120℃, 130℃, 140℃, 150℃ or 165℃, etc., depending on the actual use requirements) for 4h~12h (which can be 4h, 6h, 8h, 10h or 12h, etc., depending on the actual use requirements).

[0025] During the hydrothermal reaction, Ti3C2 is oxidized to form TiO2, and Li + / Na + By replacing anatase TiO2, in-situ LiTiO2 / Ti3C2 (or Na2Ti3O7 / Ti3C2) nanocomposites are generated. Ti3C2 is used as the substrate material, providing a large number of active sites for lithium ion insertion and extraction. Since the size of the in-situ grown nanoparticles is controllable and the nanoparticles are uniformly distributed, this is beneficial for stabilizing the layered structure of Ti3C2 during cycling. Therefore, the Ti3C2-based composite materials of this application (such as LiTiO2 / Ti3C2 nanocomposites or Na2Ti3O7 / Ti3C2 nanocomposites) exhibit better electrochemical performance than Ti3C2.

[0026] If the hydrothermal reaction temperature is too low, nanoparticles cannot be generated; if the hydrothermal reaction temperature is too high, the Ti3C2 substrate material will be oxidized by heat, causing the layered structure to collapse, thereby reducing the electrochemical performance of the composite material. If the hydrothermal reaction time is too long, the Ti3C2 material will be oxidized by heat, causing the layered structure to collapse, thereby reducing the electrochemical performance of the composite material; if the hydrothermal reaction time is too short, it will be detrimental to the generation of nanoparticles.

[0027] The hydrothermal reaction is carried out in a high-pressure reactor.

[0028] The centrifugation rate is 2000 r / min. -1 ~9000r min -1 (Based on actual usage needs, it can be 2000r min) -1 5000r min -1 6000r min -1 7000r min -1 Or 9000r min -1 (etc.), preferably 6000 rpm. -1 ~9000r min -1 The centrifugation time is 4 min to 6 min.

[0029] The washing process uses deionized water.

[0030] The drying process is vacuum drying.

[0031] The vacuum drying temperature is 75℃~85℃ (it can be 75℃, 78℃, 80℃ or 85℃, etc., depending on the actual use), preferably 80℃; the vacuum drying time is 10h~20h (it can be 10h, 12h, 15h, 18h or 20h, etc., depending on the actual use), preferably 12h.

[0032] Furthermore, embodiments of the present invention also provide applications of the Ti3C2-based composite material, which can be used in battery materials, hydrogen storage materials, and supercapacitors.

[0033] In a preferred embodiment, the battery material is a lithium-ion battery anode material.

[0034] Compared with the prior art, the embodiments of the present invention have the following technical effects:

[0035] (1) The Ti3C2-based composite material of this application has uniform particle size, which can effectively suppress the collapse and recombination of the accordion-like sheet structure of Ti3C2 material, and at the same time provide a large number of active sites (such as active sites for lithium ion insertion and extraction); moreover, the morphology of the Ti3C2-based composite material is well maintained and the purity is high, and it can still maintain the initial morphology after hydrothermal reaction.

[0036] (2) The preparation method of this application is simple, easy to operate, and has a short experimental cycle. During the hydrothermal reaction, the by-product TiO2 nanoparticles play an important role in the targeted introduction of lithium / sodium ions, which greatly enhances the electrochemical performance of Ti3C2. This makes the prepared Ti3C2-based composite material have good electrochemical performance and can be applied to battery materials, hydrogen storage materials and supercapacitors, etc., and has good performance. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 The X-ray diffraction (XRD) patterns of Ti3AlC2, Ti3C2, LiTiO2 / Ti3C2 nanocomposites and Na2Ti3O7 / Ti3C2 nanocomposites are shown in the embodiments of the present invention.

[0039] Figure 2The images are FESEM images of Ti3C2, LiTiO2 / Ti3C2 nanocomposites and Na2Ti3O7 / Ti3C2 nanocomposites from embodiments of the present invention.

[0040] Figure 3 These are HRTEM images of the LiTiO2 / Ti3C2 nanocomposite material and the Na2Ti3O7 / Ti3C2 nanocomposite material from embodiments of the present invention.

[0041] Figure 4 XPS spectra of LiTiO2 / Ti3C2 nanocomposites and Na2Ti3O7 / Ti3C2 nanocomposites from embodiments of the present invention;

[0042] Figure 5 The electrochemical performance, long-cycle capacity performance, and corresponding coulombic efficiency of LiTiO2 / Ti3C2 nanocomposites and Na2Ti3O7 / Ti3C2 nanocomposites in the embodiments of the present invention are shown.

[0043] Figure 6 The variable magnification performance diagrams of the LiTiO2 / Ti3C2 nanocomposite material and the Na2Ti3O7 / Ti3C2 nanocomposite material in embodiments of the present invention are shown.

[0044] Figure 7 The CV curves of the LiTiO2 / Ti3C2 nanocomposite material and the Na2Ti3O7 / Ti3C2 nanocomposite material in the embodiments of the present invention are shown.

[0045] Figure 8 The CV curves of the LiTiO2 / Ti3C2 nanocomposite material in this embodiment of the invention at different scan rates and the contribution of the non-diffusion confinement current at different scan rates are shown.

[0046] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be noted that if the embodiments of the present invention involve descriptions such as "first" and "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0049] In the embodiments of this application, all reagents and raw materials used are commercially available products; the concentration of the HF solution is 40 wt%; the lithium hydroxide described in the embodiments of this application is lithium hydroxide (monohydrate); both lithium hydroxide (monohydrate) and sodium hydroxide are analytical grade; the purity of the MAX precursor is 98%, 200 mesh.

[0050] The embodiments of this application can effectively control the morphology and size of the product, the process is simple, and the obtained product has high purity, good dispersibility of nanoparticles, uniform particle size, and good electrochemical performance.

[0051] Example 1

[0052] A Ti3C2-based composite material includes a Ti3C2 substrate material and nanoparticles loaded on the Ti3C2 substrate material; based on the mass of the Ti3C2-based composite material as 100%, the mass percentage of the Ti3C2 substrate material is 80%, and the mass percentage of the nanoparticles is 20%.

[0053] The nanoparticles are LiTiO2 nanoparticles.

[0054] The preparation method of the Ti3C2-based composite material includes the following steps:

[0055] SO1. Add 100 mg of Ti3C2 powder to 50 ml of the first solution and stir until homogeneous to obtain a mixed solution;

[0056] SO2, the mixture from step S01 is subjected to a hydrothermal reaction to obtain a reaction product; the reaction product is centrifuged, the precipitate is collected, washed, and dried to obtain a Ti3C2-based composite material (i.e., LiTiO2 / Ti3C2 nanocomposite material); the hydrothermal reaction is carried out at 160℃ for 12 hours.

[0057] In step S01,

[0058] The Ti3C2 powder was prepared by the following method: under ice bath conditions, 1g of MAX precursor was added to 20ml of the second solution (added over 30min) for etching, then centrifuged, the precipitate was collected, washed, and dried to obtain Ti3C2 powder.

[0059] The MAX precursor is Ti3AlC2; the second solution is a 40wt% HF solution. The etching temperature is 50℃; the etching time is 36h.

[0060] The centrifugation rate is 7000 r / min. -1 The centrifugation time was 6 minutes.

[0061] The washing process uses deionized water (washing continues until the pH of the supernatant is approximately 6).

[0062] The drying process is vacuum drying. The vacuum drying temperature is 75°C, and the vacuum drying time is 20 hours.

[0063] The first solution is an aqueous solution of LiOH, which is prepared by adding 2.098 g of lithium hydroxide (monohydrate) to 50 mL of deionized water and stirring magnetically for 30 min to obtain an aqueous solution of LiOH.

[0064] The stirring is magnetic stirring.

[0065] In step S02,

[0066] The hydrothermal reaction was carried out in a high-pressure reactor (100mL polytetrafluoroethylene-lined stainless steel high-pressure reactor).

[0067] The centrifugation rate is 8000 r / min. -1 The centrifugation time was 5 minutes.

[0068] The washing process uses deionized water.

[0069] The drying process is vacuum drying. The vacuum drying temperature is 80°C; the vacuum drying time is 12 hours.

[0070] The Ti3C2-based composite material can be used in battery materials. The battery material is a negative electrode material for lithium-ion batteries.

[0071] Example 2

[0072] A Ti3C2-based composite material includes a Ti3C2 substrate material and nanoparticles loaded on the Ti3C2 substrate material; based on the mass of the Ti3C2-based composite material as 100%, the mass percentage of the Ti3C2 substrate material is 96%, and the mass percentage of the nanoparticles is 4%.

[0073] The nanoparticles are Na2Ti3O7 nanoparticles.

[0074] The preparation method of the Ti3C2-based composite material includes the following steps:

[0075] SO1. Add 100 mg of Ti3C2 powder to 50 ml of the first solution and stir until homogeneous to obtain a mixed solution;

[0076] SO2, the mixture from step S01 is subjected to a hydrothermal reaction to obtain a reaction product; the reaction product is centrifuged, the precipitate is collected, washed, and dried to obtain a Ti3C2-based composite material (i.e., Na2Ti3O7 / Ti3C2 nanocomposite material); the hydrothermal reaction is carried out at 180℃ for 10 hours.

[0077] In step S01,

[0078] The Ti3C2 powder was prepared by the following method: under ice bath conditions, 1g of MAX precursor was added to 20ml of the second solution (added over 30min) for etching, then centrifuged, the precipitate was collected, washed, and dried to obtain Ti3C2 powder.

[0079] The MAX precursor is Ti3AlC2; the second solution is a 40wt% HF solution.

[0080] The etching temperature is 60°C; the etching time is 36 hours.

[0081] The centrifugation rate is 9000 r / min. -1 The centrifugation time was 4 minutes.

[0082] The washing process uses deionized water (washing continues until the pH of the supernatant is approximately 6).

[0083] The drying process is vacuum drying. The vacuum drying temperature is 85°C, and the vacuum drying time is 10 hours.

[0084] The first solution is an aqueous solution of NaOH, which is prepared by adding 2g of sodium hydroxide to 50mL of deionized water and stirring magnetically for 30min to obtain the aqueous solution of NaOH.

[0085] The stirring is magnetic stirring.

[0086] In step S02,

[0087] The hydrothermal reaction was carried out in a high-pressure reactor (100mL polytetrafluoroethylene-lined stainless steel high-pressure reactor).

[0088] The centrifugation rate is 8000 r / min. -1 The centrifugation time was 6 minutes.

[0089] The washing process uses deionized water.

[0090] The drying process is vacuum drying.

[0091] The vacuum drying temperature is 80℃; the vacuum drying time is 12 hours.

[0092] The Ti3C2-based composite material can be used in battery materials. The battery material is a negative electrode material for lithium-ion batteries.

[0093] Example 3

[0094] A Ti3C2-based composite material includes a Ti3C2 substrate material and nanoparticles loaded on the Ti3C2 substrate material; based on the mass of the Ti3C2-based composite material as 100%, the mass percentage of the Ti3C2 substrate material is 90%, and the mass percentage of the nanoparticles is 10%.

[0095] The nanoparticles are LiTiO2 nanoparticles.

[0096] The preparation method of the Ti3C2-based composite material includes the following steps:

[0097] SO1. Add 100 mg of Ti3C2 powder to 50 ml of the first solution and stir until homogeneous to obtain a mixed solution;

[0098] SO2, the mixture from step S01 is subjected to a hydrothermal reaction to obtain a reaction product; the reaction product is centrifuged, the precipitate is collected, washed, and dried to obtain a Ti3C2-based composite material (i.e., LiTiO2 / Ti3C2 nanocomposite material); the hydrothermal reaction is carried out at 120℃ for 6 hours.

[0099] In step S01,

[0100] The Ti3C2 powder was prepared by the following method: under ice bath conditions, 1g of MAX precursor was added to 20ml of the second solution (added over 30min) for etching, then centrifuged, the precipitate was collected, washed, and dried to obtain Ti3C2 powder.

[0101] The MAX precursor is Ti3AlC2; the second solution is a 40wt% HF solution.

[0102] The etching temperature is 40°C; the etching time is 36 hours.

[0103] The centrifugation rate is 9000 r / min.-1 The centrifugation time was 4 minutes.

[0104] The washing process uses deionized water (washing continues until the pH of the supernatant is approximately 6).

[0105] The drying process is vacuum drying.

[0106] The vacuum drying temperature is 75°C, and the vacuum drying time is 20 hours.

[0107] The first solution is an aqueous solution of LiOH, prepared by the following method: 1.2 g of lithium hydroxide is added to 50 mL of deionized water, and the mixture is magnetically stirred for 30 min to obtain the aqueous solution of LiOH. The stirring is magnetic stirring.

[0108] In step S02,

[0109] The hydrothermal reaction was carried out in a high-pressure reactor (100mL polytetrafluoroethylene-lined stainless steel high-pressure reactor).

[0110] The centrifugation rate is 9000 r / min. -1 The centrifugation time was 4 minutes.

[0111] The washing process uses deionized water.

[0112] The drying process is vacuum drying. The vacuum drying temperature is 75°C; the vacuum drying time is 20 hours.

[0113] The Ti3C2-based composite material can be used in battery materials. The battery material is a negative electrode material for lithium-ion batteries.

[0114] Example 4

[0115] A Ti3C2-based composite material includes a Ti3C2 substrate material and nanoparticles loaded on the Ti3C2 substrate material; based on the mass of the Ti3C2-based composite material as 100%, the mass percentage of the Ti3C2 substrate material is 85%, and the mass percentage of the nanoparticles is 15%.

[0116] The nanoparticles are LiTiO2 nanoparticles.

[0117] The preparation method of the Ti3C2-based composite material includes the following steps:

[0118] SO1. Add 100 mg of Ti3C2 powder to 50 ml of the first solution and stir until homogeneous to obtain a mixed solution;

[0119] SO2, the mixture from step S01 is subjected to a hydrothermal reaction to obtain a reaction product; the reaction product is centrifuged, the precipitate is collected, washed, and dried to obtain a Ti3C2-based composite material (i.e., LiTiO2 / Ti3C2 nanocomposite material); the hydrothermal reaction is carried out at 185℃ for 2 hours.

[0120] In step S01,

[0121] The Ti3C2 powder was prepared by the following method: under ice bath conditions, 1g of MAX precursor was added to 20ml of the second solution (added over 30min) for etching, then centrifuged, the precipitate was collected, washed, and dried to obtain Ti3C2 powder.

[0122] The MAX precursor is Ti3AlC2; the second solution is a 40wt% HF solution. The etching temperature is 60℃; the etching time is 36h.

[0123] The centrifugation rate is 7000 r / min. -1 The centrifugation time was 6 minutes.

[0124] The washing process uses deionized water (washing continues until the pH of the supernatant is approximately 6).

[0125] The drying process is vacuum drying. The vacuum drying temperature is 85°C, and the vacuum drying time is 10 hours.

[0126] The first solution is an aqueous solution of LiOH, prepared by the following method: 1.2 g of lithium hydroxide is added to 50 mL of deionized water, and the mixture is magnetically stirred for 30 min to obtain the aqueous solution of LiOH. The stirring is magnetic stirring.

[0127] The stirring is magnetic stirring.

[0128] In step S02,

[0129] The hydrothermal reaction was carried out in a high-pressure reactor (100mL polytetrafluoroethylene-lined stainless steel high-pressure reactor).

[0130] The centrifugation rate is 9000 r / min. -1 The centrifugation time was 5 minutes.

[0131] The washing process uses deionized water.

[0132] The drying process is vacuum drying. The vacuum drying temperature is 75°C; the vacuum drying time is 18 hours.

[0133] The Ti3C2-based composite material can be used in battery materials. The battery material is a negative electrode material for lithium-ion batteries.

[0134] Effect Example

[0135] The electrochemical energy of the prepared Ti3C2-based composite materials was tested: First, 80 mg of the LiTiO2 / Ti3C2 nanocomposite material from Example 1 was added to a first agate mortar containing 10 mg of conductive carbon black, and 80 mg of the Na2Ti3O7 / Ti3C2 nanocomposite material from Example 2 was added to a second agate mortar containing 10 mg of conductive carbon black. The materials were ground for 0.5 h under an argon atmosphere. After thorough grinding, the mixture was placed in a small glass bottle, and 200 μL of a prepared PVDF / NMP solvent (concentration 0.05 g / mL) was added. -1 Add an appropriate amount of NMP solvent and stir continuously on a stirrer for 12 hours to form a black slurry. Use a four-sided wet film preparation device to evenly coat the slurry onto copper foil (approximately 150 μm thick). Before use, wipe the copper foil with anhydrous ethanol to ensure a clean and impurity-free surface. Place it in a 120°C vacuum drying oven for 12 hours to dry. Press the dried copper foil sheet using an electric roller press to ensure stable contact between the slurry and the copper foil. Cut electrode sheets with a diameter of 14 mm using a slicing machine, and weigh the electrode sheets for use. Select a lithium metal sheet with a thickness of approximately 0.4 mm and a diameter of 14 mm as the counter electrode, and assemble a coin cell in an argon glove box. The oxygen content and water content in the glove box are below 0.01 ppm.

[0136] To confirm the phase composition and crystal structure of Ti3AlC2, Ti3C2, the LiTiO2 / Ti3C2 nanocomposite material of Example 1, and the Na2Ti3O7 / Ti3C2 nanocomposite material of Example 2, XRD pattern analysis was performed. The results are shown in [Figure 1]. Figure 1In the XRD pattern of Ti3C2, the peak at 39° disappeared, and the diffraction peaks corresponding to (104) and (002) of Ti3AlC2 were shifted to lower angles, indicating that the Al intercalation of Ti3AlC2 was successfully dissolved by HF solution. Furthermore, the diffraction peak (002) of Na2Ti3O7 / Ti3C2 nanocomposite shifted from 9.70° to 9.02° after NaOH treatment, while the peak of LiTiO2 / Ti3C2 nanocomposite shifted to a lower angle of 7.15°, indicating a corresponding increase in interlayer spacing. Calculations using the Bragg equation showed that the interlayer spacings of Ti3C2, LiTiO2 / Ti3C2 nanocomposite, and Na2Ti3O7 / Ti3C2 nanocomposite were 0.91, 0.98, and 1.20 nm, respectively. Meanwhile, the (110) peak appeared in all samples, indicating that the reaction of Ti3C2 with LiOH and NaOH did not completely destroy the layered structure of Ti3C2. XRD analysis of the LiTiO2 / Ti3C2 nanocomposite material revealed characteristic peaks for both LiTiO2 and Ti3C2, indicating the formation of a new LiTiO2 phase within the composite. XRD analysis of the Na2Ti3O7 / Ti3C2 nanocomposite material showed only the detection of a new Na2Ti3O7 phase. The Ti3C2 in both the LiTiO2 / Ti3C2 and Na2Ti3O7 / Ti3C2 nanocomposite materials underwent partial oxidation during hydrothermal treatment, forming TiO2. XRD results indicated two types of TiO2 in the Na2Ti3O7 / Ti3C2 nanocomposite material: anatase TiO2 (ICDD PDF#21-1272) and rutile TiO2 (ICDD PDF#21-1276). However, only narrow-bandgap rutile TiO2 was detected in both the Ti3C2 and LiTiO2 / Ti3C2 nanocomposite materials, which contributes to improved electrochemical performance.

[0137] like Figure 2 As shown in (ac), the microstructures of Ti3C2, the LiTiO2 / Ti3C2 nanocomposite of Example 1, and the Na2Ti3O7 / Ti3C2 nanocomposite of Example 2 were characterized by FESEM. Figure 2 In (a), Ti3C2 exhibits a typical layered structure. Figure 2Images (b) and (c) show the microstructures of the LiTiO2 / Ti3C2 and Na2Ti3O7 / Ti3C2 nanocomposites, respectively. It can be seen that LiTiO2 and Na2Ti3O7 grow on the Ti3C2 layers, and Ti3C2 acts as a support, effectively maintaining the layered structure. Furthermore, the LiTiO2 nanoparticles in the LiTiO2 / Ti3C2 nanocomposite are smaller, finer, and more uniformly distributed than the Na2Ti3O7 nanoparticles in the Na2Ti3O7 / Ti3C2 nanocomposite. The presence of LiTiO2 nanoparticles increases the spacing between the Ti3C2 layers and supports the layered structure.

[0138] Figure 3 HRTEM images of the LiTiO2 / Ti3C2 nanocomposite prepared in Example 1 are shown. As shown, small LiTiO2 particles are distributed on the Ti3C2 layer. Figure 3 The fast Fourier transform and inverse fast Fourier transform were used to analyze the crystal planes, and the interplanar spacing was calculated to be 0.205 nm, corresponding to the (200) plane of LiTiO2. This result is consistent with the conclusion of SEM, that is, the nanoparticles are grown on the surface of Ti3C2 thin film.

[0139] The structural information of the LiTiO2 / Ti3C2 nanocomposite material in Example 1 and the Na2Ti3O7 / Ti3C2 nanocomposite material in Example 2 was further determined by XPS. Ti, O, C, and F were the main elements in the samples. F was a residue from the etching process. Further analysis of Ti 2p( Figure 4 (a), (b)), C 1s( Figure 4 (c), (d)) and O1s Figure 4 High-resolution XPS spectra (e) and (f) show six distinct peaks observed in the high-resolution Ti 2p orbital. Based on the 2p orbital binding energies of the LiTiO2 / Ti3C2 and Na2Ti3O7 / Ti3C2 nanocomposites, it can be found that Ti contains three valence states, namely Ti... 2+ Ti 3 + and Ti 4+ In these three Ti states (C-Ti-C, C-Ti-O, and O-Ti-O), the binding energies of 455.2 and 461.8 eV, 456.3 and 463.2 eV, and 468.6 and 464.5 eV correspond to the 2p3 / 2 and 2p1 / 2 spin states, respectively. High-resolution C1s spectra of the two samples (…) Figure 4(c) and (d) contain three peaks, corresponding to Ti-C (281.9 eV), CO (288.7 eV), and CC (285.1 eV), respectively. These results confirm that during the fabrication of Ti3C2, the Ti-C bonds were not mostly broken, nor were they completely oxidized to Ti-O bonds, thus preserving the original structure relatively well.

[0140] Figure 5 For a voltage range of 0.1V to 3.0V and 0.1A g -1 The battery performance data and long-term cycling capability of the LiTiO2 / Ti3C2 nanocomposite material in Example 1 and the Na2Ti3O7 / Ti3C2 nanocomposite material in Example 2 were analyzed at the specified current density. The initial discharge capacity of the LiTiO2 / Ti3C2 nanocomposite material was 551.5 mA hg. -1 Higher than Na2Ti3O7 / Ti3C2 nanocomposite material (470 mA hg) -1 The initial coulombic efficiency (ICE) of the LiTiO2 / Ti3C2 nanocomposite was 52.3%, and the initial capacitance was reduced by the formed SEI film and Li. + The decay is due to partially irreversible reactions between the LiTiO2 / Ti3C2 surface groups (-OH, -F, and -O). For the second and third cycles, the discharge specific capacities of the LiTiO2 / Ti3C2 nanocomposite were 312.3 and 287.1 mA hg, respectively. -1 At 0.1A g -1 At the specified current density, the LiTiO2 / Ti3C2 nanocomposite exhibited better cycling performance, showing a slight upward trend after 200 cycles, while the Na2Ti3O7 / Ti3C2 nanocomposite showed a more stable trend, with a final capacity of 321.1 mA hg. -1 This phenomenon can be explained by the increased interlayer spacing of Ti3C2 due to the insertion and removal of lithium ions during charging / discharging. LiTiO2 and Na2Ti3O7 nanoparticles play a supporting role in the layered structure. These changes enable LiTiO2 / Ti3C2 nanocomposites and Na2Ti3O7 / Ti3C2 nanocomposites to provide more active sites to improve ion migration dynamics.

[0141] like Figure 6 As shown, the LiTiO2 / Ti3C2 nanocomposite of Example 1 exhibits better rate performance than the Na2Ti3O7 / Ti3C2 nanocomposite of Example 2. With current density increasing from 0.1 A g... -1 Increase to 5A g -1The specific capacity of the LiTiO2 / Ti3C2 nanocomposite material increased from 337.2 mA hg. -1 It dropped to 101.8 mA hg -1 Afterwards, the current density recovered to 0.1 Ag. -1 The capacity of the LiTiO2 / Ti3C2 nanocomposite increased to 372.3 mA hg. -1 This indicates that the two-dimensional structure of the LiTiO2 / Ti3C2 nanocomposite exhibits excellent rate performance. Compared with the Na2Ti3O7 / Ti3C2 nanocomposite at the same current density, the LiTiO2 / Ti3C2 nanocomposite shows a higher capacity. At 0.1 and 0.2 A g... -1 Within the current density range, the LiTiO2 / Ti3C2 nanocomposite exhibits a different capacity than the Na2Ti3O7 / Ti3C2 nanocomposite. The capacity increases with cycling, which may be related to the permeation through continuously activated electrolytes. This phenomenon can be inferred as an improvement in ion diffusion kinetics.

[0142] The lithium storage behavior of the composite material was studied by cyclic voltammetry (CV). Figure 7 The left and right images respectively show the LiTiO2 / Ti3C2 nanocomposite material of Example 1 and the Na2Ti3O7 / Ti3C2 nanocomposite material of Example 2 at 0.1 mV s. -1 The initial three CV curves were obtained at the scan rate and within a potential range of 0.01 V to 3.0 V. In the first cathode scan, a cathode peak appeared at approximately 1.516 V when lithium ions intercalated into the intercalation layer. This peak then shifted to 1.566 V and 1.614 V in subsequent cycles, attributed to electrolyte decomposition and the formation of a solid electrolyte interphase (SEI) layer on the electrode surface, illustrating the distinctly irreversible cathode peak at 0.431 V. In the subsequent anodic scan, a relatively strong peak appeared at 1.801 V and a relatively weak peak at 2.644 V. In subsequent cycles, both the anodic and cathode peaks shifted to the right, indicating that Li... + The gradual extraction was observed. In contrast, the Na2Ti3O7 / Ti3C2 nanocomposite exhibited irreversible cathode peaks at 0.46V and 1.62V. In the first cycle, lithium-ion insertion resulted in a cathode peak at 1.31V, which shifted to approximately 1.4V in subsequent cycles.

[0143] To further investigate the storage mechanism of this electrode, it was tested at concentrations of 0.1, 0.2, 0.4, 0.6, 0.8, and 1.0 mV·s. -1 The LiTiO2 / Ti3C2 nanocomposite material of Example 1 was subjected to CV testing. Figure 8As shown in (a), the peak anode current gradually increases with increasing scan rate. The relationship between the peak current (i) and the scan rate (v) can be described by formula (1):

[0144] log(i)=b*log(v)+log(a) (0.5≤b≤1) (1)

[0145] Where a and b are two variable parameters. The lithium-ion storage mechanism is determined by the value of b. Generally, b = 0.5 indicates that diffusion completely controls lithium-ion storage, and b = 1 indicates that storage is completely controlled by capacitance. In the embodiments of this application, the calculated b values ​​for the anode and cathode peaks of the electrode are 0.852 and 0.932, respectively. Figure 8 (b) indicates that the lithium-ion storage process in the lithium electrode is controlled by capacitance and diffusion processes.

[0146] According to formula (2), the contribution of the capacitive process is further quantified:

[0147] (v)=k1 v+k2 v1 / (2i(v)) (2)

[0148] Where k1 and k2 are two variables; k1v and k2v1 / 2 represent the contributions of the capacitance and diffusion control processes, respectively. Figure 8 As shown in (c), for the Li electrode, at a scan rate of 0.4 mV·s -1 At that time, the capacitance contribution was 62.7%. The percentage of capacitance contribution gradually increased with increasing scan rate, from 0.1 mV·s. -1 46.5% to 1 mV·s -1 76.7% at that time Figure 8 (d) This indicates that lithium-ion insertion / extraction can be achieved more efficiently at higher scan rates due to the rapid reaction kinetics of the capacitive storage mechanism. Therefore, a higher capacitance contribution rate will play a conductive role in ion transport and improve the high-rate performance of the electrode.

[0149] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A Ti3C2-based composite material, characterized in that, The composite material comprises a Ti3C2 substrate material and nanoparticles loaded on the Ti3C2 substrate material; based on the mass of the Ti3C2-based composite material as 100%, the mass percentage of the Ti3C2 substrate material is 80%–96%, and the mass percentage of the nanoparticles is 4%–20%. The nanoparticles are LiTiO2 nanoparticles or Na2Ti3O7 nanoparticles. The preparation method of the Ti3C2-based composite material includes the following steps: S01. Add Ti3C2 powder to the first solution and stir until homogeneous to obtain a mixed solution; add 50mg to 200mg of Ti3C2 powder to every 30ml to 100ml of the first solution; S02. The mixture from step S01 is subjected to a hydrothermal reaction to obtain a reaction product; the reaction product is centrifuged, the precipitate is collected, washed, and dried to obtain a Ti3C2-based composite material; the hydrothermal reaction conditions are 75℃~185℃ for 2 h~16 h. The first solution is an aqueous solution of LiOH or an aqueous solution of NaOH.

2. The Ti3C2-based composite material according to claim 1, characterized in that, In step S01, the Ti3C2 powder is prepared by the following method: the MAX precursor is added to the second solution for etching, then centrifuged, the precipitate is collected, washed, and dried to obtain Ti3C2 powder; 0.5g to 2g of MAX precursor is added to every 10ml to 40ml of the second solution.

3. The Ti3C2-based composite material according to claim 2, characterized in that, The MAX precursor is Ti3AlC2; the second solution is an HF solution; The etching temperature is 40℃~60℃; the etching time is 36 h; The centrifugation rate was 2000 r / min. -1 ~9000 r min -1 The centrifugation time is 4 min to 6 min. The drying process is vacuum drying; the vacuum drying temperature is 75℃~85℃, and the vacuum drying time is 10h~20h.

4. The Ti3C2-based composite material according to claim 1, characterized in that, In step S01, the stirring is magnetic stirring.

5. The Ti3C2-based composite material according to claim 1, characterized in that, In step S02, the hydrothermal reaction is carried out at 100℃~165℃ for 4 h~12 h.

6. The Ti3C2-based composite material according to claim 1, characterized in that, In step S02, the centrifugation rate is 2000 r / min. -1 ~9000 r min -1 The centrifugation time is 4 min to 6 min. The drying process is vacuum drying; the vacuum drying temperature is 75℃~85℃; and the vacuum drying time is 10h~20h.

7. The application of the Ti3C2-based composite material according to claim 1, characterized in that, The Ti3C2-based composite material is used in battery materials, hydrogen storage materials, and supercapacitors.

8. The application of the Ti3C2-based composite material according to claim 7, characterized in that, The battery material is a lithium-ion battery anode material.

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