A 3D-CNS@Mo2Ti2C3T x Method for preparing composite derivative of MXene and application thereof

Abstract

The application relates to a 3D-CNS@Mo2Ti2C3T x The application relates to a preparation method and application of a composite derivative of MXene, and belongs to the field of secondary battery negative materials. The preparation method comprises the following steps: 3D-CNS is prepared by chemical vapor deposition with ferrocene as a catalyst precursor and 1,2-dichlorobenzene as a carbon source; a multilayer Mo2Ti2C3T x Mxenes; 3D-CNS is used as a flexible substrate, and the multilayer Mo2Ti2C3T x MXene solution is used as an electroplating solution, a platinum sheet is used as a counter electrode, and electroplating is carried out under constant voltage; then, freeze-drying is carried out, sintering is carried out under inert gas protection, and thus, 3D-CNS@Mo2Ti2C3T x The application relates to a composite derivative of MXene. The prepared integrated self-supporting electrode transmits high-power type lithium storage performance with energy type.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of secondary battery negative electrode materials, in particular to a three-dimensional porous carbon nanotube and Mo2Ti2C3T x MXenes-based composite negative electrode material, preparation method and application thereof. BACKGROUND

[0002] At present, electric vehicles (EV) and the like exhibit green sustainability advantages such as intelligent interconnection, high energy efficiency, environmental friendliness, and diversity of energy sources, and the like, and are increasingly favored by the society. However, compared with fuel vehicles, the cruising range of electric vehicles still has certain limitations; compared with the refueling time of fuel vehicles, the charging time of electric vehicles is still relatively long; meanwhile, the vehicle battery still has the problem that the energy storage capacity gradually decreases with the increase of use time, resulting in relatively high battery cost.

[0003] Traditional battery materials have slow electrochemical kinetics due to diffusion-controlled redox processes, resulting in high energy density and relatively low power density; supercapacitors have very fast charging time (order of seconds) due to the surface or near-surface controlled ion adsorption charge storage mechanism of the materials, but the energy storage energy is relatively low. A large number of previous studies have confirmed that the pseudo-capacitive material has a charge storage mechanism of battery-like redox reaction, but its rate performance can be compared with traditional electrochemical double-layer capacitors; therefore, these materials provide a way for the development of electrodes with high power density and considerable energy density.

[0004] Two-dimensional transition metal carbon and / or nitride-Mxenes (general formula: M n+1 X n T x ; n = 1-4; M = Ti, Nb, Mo, V, Zr...; X = C, N; T x = -O, -OH, -F, -Cl...), which were first reported by Professor Yury Gogotsi's research group at Drexel University in 2011, have attracted extensive research attention since then due to their intrinsic suitability for energy storage electrodes, such as metallic conductivity, rich adjustable surface functional groups, and two-dimensional ion transport channels. At present, due to the van der Waals forces between the MXenes layers, the layers are prone to self-stacking, and the MXene pseudo-capacitive charge storage mechanism, the embedded ions and the surface functional groups of MXenes only induce slight redox depth. Meanwhile, the intrinsic rigidity of the M-X bond in MXene makes it difficult to deform to accommodate foreign ions. Therefore, the lithium storage specific capacity of MXenes in actual energy storage applications still cannot meet the demand for high-power and high-energy density materials.

[0005] Compared with the single-metal MXenes, the double-metal MXenes have more atomic layers and larger interlayer spacing. However, the preparation process of the double-metal MXenes, including etching and subsequent interlayer peeling, is still relatively complex and time-consuming. In addition, compared with the single-metal MXenes electrode materials reported at present, the synthesized double-metal MXenes electrode materials do not exhibit significant competitive advantages in lithium storage performance, cycle stability and rate capability. However, the rich metal composition of the M site of the double-metal MXenes makes them exhibit diversified structures and physical and chemical properties, so they are still ideal candidates for energy storage materials. The electrical properties and electrochemical behavior of the double-metal MXenes nanosheets still need to be explored. SUMMARY

[0006] The application takes 413 MAX phase-Mo2Ti2AlC3 as an example to show a process for preparing three-dimensional carbon nanotube sponge (3D-CNS)-Mo2Ti2C3T x MXene composite derivative strategy. First, pre-etched multi-layer Mo2Ti2C3T x MXenes are plated on 3D-PCNS (three-dimensional porous carbon nanosheets) to obtain a composite of 3D-CNS and Mo2Ti2C3T x Second, the composite is dried by a freeze-drying device to obtain a flexible composite derivative precursor. Finally, the obtained precursor electrode sheet is heat treated and sintered under the protection of an inert gas to prepare an integrated self-supporting 3D-CNS@Mo2Ti2C3T x MXene composite derivative electrode. The prepared integrated self-supporting electrode transmits high-power lithium storage performance with energy type.

[0007] To achieve the above object, the technical scheme adopted by the application is:

[0008] A 3D-CNS@Mo2Ti2C3T x MXene composite derivative preparation method, comprising the following steps:

[0009] (1) Preparation of 3D-CNS

[0010] Ferrocene is used as a precursor of a catalyst, and 1,2-dichlorobenzene is used as a carbon source to synthesize by chemical vapor deposition technology;

[0011] (2) Preparation of multi-layer Mo2Ti2C3T x MXenes

[0012] Pre-etching with hydrofluoric acid, different process parameters were used to prepare multilayer Mo2Ti2C3T with different morphology and yield x Mxenes;

[0013] (3) 3D-CNS@Mo2Ti2C3T x Preparation of composite derivatives of MXenes

[0014] Acid treatment: hydrothermal treatment of 3D-CNS with concentrated nitric acid at 120℃ for 12 h, and washed with deionized water to neutral;

[0015] Electroplating solution: multilayer Mo2Ti2C3T prepared x MXenes solution was prepared as 0.5-2 M aqueous solution, ice bath probe ultrasonic for 30 min;

[0016] Electroplating process: the 3D-CNS hydrothermally treated with concentrated nitric acid as a flexible substrate, multilayer Mo2Ti2C3T x MXenes solution was used as the electroplating solution, platinum sheet was used as the counter electrode, and the electroplating was carried out at a constant voltage of 3 V-20 V for 5 min-60 min;

[0017] Heat treatment: 3D-CNS@Mo2Ti2C3T after electroplating x Freeze-drying of the precursor substrate of the composite derivative of MXenes, sintering at 400℃-600℃ for 1 h-3 h under inert gas protection.

[0018] Further, the specific process parameters for preparing 3D-CNS in step (1) are as follows:

[0019] Solution preparation: ferrocene powder was dissolved in 1,2-dichlorobenzene to prepare a solution with a concentration of 0.03-0.08 g·mL -1 ;

[0020] Solution delivery: the solution from the previous step was continuously injected into the quartz tube in the resistance furnace at a rate of 0.1-0.2 mL·min -1 ;

[0021] Reaction conditions: the temperature in the furnace was set to 700-1000℃;

[0022] Gas delivery: a mixture of argon and hydrogen gas was used as the carrier gas, with flow rates set at 2000 mL·min -1 and 300 mL·min -1 , respectively;

[0023] Growth substrate: a 2 inch x 1 inch quartz sheet was placed in the reaction area as the growth substrate for carbon nanotube sponge;

[0024] Collecting product: after 2-5 h of growth time, collect the formed three-dimensional carbon nanotube sponge with a certain thickness from the quartz substrate.

[0025] Further, the specific process of the pre-etching is:

[0026] Bimetallic MAX phase precursor: Mo2Ti2AlC3 addition amount is 0.5 g-3 g;

[0027] Etchant: 49 wt% HF, addition amount 15 mL-40 mL;

[0028] Pre-etching time: 120 h-168 h, to ensure sufficient pre-etching effect;

[0029] Pre-etching temperature: 55℃-65℃, to optimize the etching reaction. By adjusting the addition amount of MAX phase and HF and the etching time, multilayer Mo2Ti2C3T x Mxenes, different combinations of these variables will affect the morphology and yield of the final product.

[0030] A 3D-CNS@Mo2Ti2C3T x The composite derivative of MXene is used as a negative electrode material in a lithium ion battery.

[0031] Further, the 3D-CNS@Mo2Ti2C3T x The composite derivative of MXene as a negative electrode material has a lithium storage capacity of 726 mAh / g in a lithium ion battery at a current density of 5 A / g.

[0032] Compared with the prior art, the beneficial effects of the present application are:

[0033] The present application utilizes electroplating process combined with subsequent heat treatment to prepare 3D-CNS@Mo2Ti2C3T x The composite derivative of MXene, the prepared 3D-CNS@Mo2Ti2C3T x The composite derivative of MXene, Mo2Ti2C3T x The electrochemically inactive M-X bond part in MXenes is effectively activated, effectively enriching the lithium storage sites of the derivative material, while synergistically inheriting and exerting the excellent electrical conductivity and good flexibility of 3D-CNS. Also further improves the specific capacity of the derivative material for storing lithium under large current density. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 Multilayer Mo2Ti2C3T xScanning electron microscope images of MXenes;

[0035] Figure 2 3D-CNS@Mo2Ti2C3T prepared for the present embodiment 1 x Transmission electron microscope images of the composite derivative of MXene;

[0036] Figure 3 3D-CNS and 3D-CNS@Mo2Ti2C3T prepared for the present embodiment 1 x XRD test results of the composite derivative of MXene;

[0037] Figure 4 3D-CNS@Mo2Ti2C3T prepared for the present embodiment 1 x Composite derivative of MXene, 3D-CNS and multilayer Mo2Ti2C3T x Cycle performance curve comparison chart of MXenes negative electrode material. DETAILED DESCRIPTION

[0038] The technical solutions and effects of the present application will be further described below in combination with the drawings and specific embodiments, but the protection scope of the present application is not limited thereto. Embodiment 1

[0039] 3D-CNS@Mo2Ti2C3T x The preparation method of the composite derivative of MXene comprises the following steps:

[0040] (1) A multilayer Mo2Ti2C3T is prepared by HF pre-etching Mo2Ti2AlC3MAX phase x MXenes;

[0041] A multilayer Mo2Ti2C3T is prepared by liquid etching method x MXenes, and the specific method is as follows:

[0042] In the process of preparing Mo2Ti2C3T x MXenes, 49wt% HF is used as etchant. First, a polytetrafluoroethylene beaker with holes is placed in a water bath. Then, 30 mL of HF is added to the polytetrafluoroethylene beaker using a pipette. Then, 2g of Mo2Ti2AlC3MAX phase is weighed and gradually added to the hydrofluoric acid solution, ensuring uniform dispersion of the powder, and finally a constant temperature water bath stirrer is started. The pre-etching process is carried out at 60℃ for 144 h, and the stirring speed is set to 500 r·min -1 After pre-etching is completed, deionized water and a high-speed centrifuge are used for cleaning until the pH value of the supernatant reaches neutral. Figure 1Pre-etched multilayer Mo2Ti2C3T x Scanning electron microscope (SEM) images of MXenes.

[0043] (2) The 3D-CNS was prepared by the CVD method, and the specific method was as follows:

[0044] The 3D-CNS was synthesized by the CVD technology, using ferrocene as a catalyst and 1,2-dichlorobenzene as a carbon source. First, the ferrocene powder was dissolved in 1,2-dichlorobenzene to prepare a 0.06 g·mL -1 solution. Then, the solution was continuously delivered into the quartz tube in the resistance furnace by the injection pump at a rate of 0.13 mL·min -1 . At a reaction temperature of 860℃, the mixed gas of Ar and H2 was used as the carrier gas, and the flow rates were set to 2000 mL·min -1 and 300 mL·min -1 , respectively. A quartz sheet was placed in the reaction area as the growth substrate of the 3D-CNS. After a growth process of 2 h, the 3D-CNS with a certain thickness was collected from the quartz substrate. The 3D-CNS was hydrothermally treated with concentrated nitric acid at 120℃ for 12 h, and then washed with deionized water until neutral to obtain the 3D-CNS@Mo2Ti2C3T x MXene composite derivative.

[0045] (3) The 3D-CNS@Mo2Ti2C3T x MXene composite derivative was prepared by the electroplating method and heat treatment process, and the specific method was as follows:

[0046] The prepared multilayer Mo2Ti2C3T x MXene solution was prepared into a 1 M plating solution and was ultrasonically treated in an ice bath probe for 30 min. Then, the 3D-CNS treated with concentrated nitric acid was used as an electrode, and a platinum sheet was used as a counter electrode. The electroplating was performed at a constant voltage of 5 V for 30 min. The 3D-CNS@Mo2Ti2C3T x MXene composite derivative precursor substrate after electroplating was freeze-dried and sintered at 500℃ for 2 h under the protection of inert gas.

[0047] The transmission electron microscope (TEM) image of the 3D-CNS@Mo2Ti2C3T x MXene composite derivative prepared in this example is shown in Figure 2 . The MXene nanosheet is uniformly loaded on the 3D-CNS substrate.

[0048] The 3D-CNS@Mo2Ti2C3T x XRD of the composite derivative of MXene is shown in Figure 3 Among them, the characteristic peaks around 25° and 45° correspond to the highly ordered graphite carbon in the 3D-CNS matrix.

[0049] The multilayer Mo2Ti2C3T x Mxenes, 3D-CNS prepared in step (2), and 3D-CNS@Mo2Ti2C3T x The composite derivative of MXene was used as an electrode as a negative electrode material, and the Mo2Ti2C3T x Mxenes, 3D-CNS, and 3D-CNS@Mo2Ti2C3T x The composite derivative of MXene was directly cut into a sheet to assemble a battery to test the electrochemical performance of the material. Among them, lithium metal was used as the counter electrode, celgard 2500 was used as the separator, and the electrolyte was 1 M LiPF6(EC:DMC=1:1 vol%). The comparison chart of the cycle performance curve is shown in Figure 4 After 100 cycles at a current density of 5 A / g, the 3D-CNS@Mo2Ti2C3T x MXene composite derivative, 3D-CNS, multilayer Mo2Ti2C3T x The specific capacity of lithium storage of MXenes was 726 mAh / g, 176 mAh / g, and 106 mAh / g, respectively. Example 2

[0050] A 3D-CNS@Mo2Ti2C3T x The preparation method of the composite derivative of MXene comprises the following steps:

[0051] (1) The Mo2Ti2AlC3MAX phase was prepared into a multilayer Mo2Ti2C3T x MXenes by HF pre-etching;

[0052] The multilayer Mo2Ti2C3T x MXenes were prepared by a liquid etching method, and the specific method was as follows:

[0053] The Mo2Ti2C3T xIn the precursor process of MXenes, 49wt% HF was used as the etchant. First, a polytetrafluoroethylene beaker with a hole was placed in a water bath. Then, 40 mL of HF was added to the polytetrafluoroethylene beaker using a pipette. Then, 2 g of Mo2Ti2AlC3 MAX phase was weighed and gradually added to the hydrofluoric acid solution, ensuring that the powder was evenly dispersed, and finally the constant temperature water bath stirrer was started. The pre-etching process was carried out at 55℃ for 168 h, and the stirring speed was set to 500 r·min -1 After the pre-etching was completed, deionized water and a high-speed centrifuge were used for cleaning until the pH value of the supernatant reached neutral.

[0054] (2) 3D-CNS was prepared by CVD method, and the specific method is as follows:

[0055] 3D-CNS was synthesized by CVD technology, using ferrocene as catalyst and 1,2-dichlorobenzene as carbon source. First, ferrocene powder was dissolved in 1,2-dichlorobenzene to prepare a 0.04 g·mL -1 solution. Then, the solution was continuously delivered into the quartz tube in the resistance furnace by the injection pump at a rate of 0.13 mL·min -1 . At a reaction temperature of 960℃, Ar and H2 mixed gas were used as carrier gas, and the flow rates were set to 2000 mL·min -1 and 300 mL·min -1 respectively. A piece of quartz sheet was placed in the reaction area as the growth substrate of 3D-CNS. After 4 h of growth process, 3D-CNS with a certain thickness was collected from the quartz substrate. The 3D-CNS was hydrothermally treated with concentrated nitric acid at 120℃ for 12 h, and then washed with deionized water until neutral to obtain 3D-CNS@Mo2Ti2C3T x MXene composite derivative.

[0056] (3) 3D-CNS@Mo2Ti2C3T x MXene composite derivative was prepared by electroplating method and heat treatment process, and the specific method is as follows:

[0057] The prepared multilayer Mo2Ti2C3T x MXene solution was prepared into a 1 M plating solution and ultrasonically treated in an ice bath for 30 min. Then, the 3D-CNS treated with concentrated nitric acid was used as the electrode, and the platinum sheet was used as the counter electrode. The electroplating was carried out at a constant voltage of 5 V for 60 min. Then, the 3D-CNS@Mo2Ti2C3T x MXene composite derivative precursor substrate was freeze-dried and sintered at 600℃ for 1 h under inert gas protection. Example 3

[0058] A 3D-CNS@Mo2Ti2C3T x A method for preparing a composite derivative of MXene, comprising the following steps:

[0059] (1) A multilayer Mo2Ti2C3T is prepared by HF pre-etching of a Mo2Ti2AlC3 MAX phase x MXenes;

[0060] A multilayer Mo2Ti2C3T is prepared by a liquid etching method x MXenes, and the specific method is as follows:

[0061] In the process of preparing a Mo2Ti2C3T x MXene precursor, 49wt% HF is used as an etchant. First, a polytetrafluoroethylene beaker with a hole is placed in a water bath. Then, 30 mL of HF is added to the polytetrafluoroethylene beaker using a pipette. Then, 2g of Mo2Ti2AlC3 MAX phase is weighed and gradually added to the hydrofluoric acid solution, ensuring uniform dispersion of the powder, and finally a constant temperature water bath stirrer is started. The pre-etching process is carried out at 65℃ for 120 h, and the stirring speed is set to 500 r·min -1 After pre-etching, deionized water and a high-speed centrifuge are used for cleaning until the pH value of the supernatant reaches neutral.

[0062] (2) A 3D-CNS is prepared by a CVD method, and the specific method is as follows:

[0063] A 3D-CNS is synthesized by CVD technology, using ferrocene as a catalyst and 1,2-dichlorobenzene as a carbon source. First, ferrocene powder is dissolved in 1,2-dichlorobenzene to prepare a 0.05 g·mL -1 solution. Then, the solution is continuously delivered into the quartz tube in the resistance furnace by a syringe pump at a rate of 0.13 mL·min -1 . At a reaction temperature of 760℃, a mixture of Ar and H2 is used as the carrier gas, and the flow rates are set to 2000 mL·min -1 and 300 mL·min -1 , respectively. A quartz sheet is placed in the reaction area as a growth substrate for the 3D-CNS. After 2 h of growth, a 3D-CNS with a certain thickness is collected from the quartz substrate. The 3D-CNS is hydrothermally treated with concentrated nitric acid at 120℃ for 12 h, and then washed with deionized water until neutral to obtain a 3D-CNS@Mo2Ti2C3T x MXene composite derivative self-supporting substrate.

[0064] (3) 3D-CNS@Mo2Ti2C3T was prepared by electroplating method and heat treatment process x Composite derivatives of MXenes, the specific method is as follows:

[0065] Using constant voltage electroplating technology, the prepared multilayer Mo2Ti2C3T x MXene solution was prepared into 0.5 M electroplating solution, and the ice bath probe was ultrasonicated for 30 min. Then, the 3D-CNS treated by concentrated nitric acid was used as an electrode, and a metal platinum sheet was used as a counter electrode. Under the constant voltage of 10 V, electroplating was carried out for 10 min. Then, the 3D-CNS@Mo2Ti2C3T x The precursor substrate of the composite derivative of MXenes was freeze-dried, and sintered at 400℃ for 3 h under inert gas protection. Example 4

[0066] A 3D-CNS@Mo2Ti2C3T x The preparation method of the composite derivative of MXenes comprises the following steps:

[0067] (1) The Mo2Ti2AlC3MAX phase was prepared into multilayer Mo2Ti2C3T x MXenes by HF pre-etching

[0068] The multilayer Mo2Ti2C3T x MXenes was prepared by liquid etching method, and the specific method is as follows:

[0069] In the process of preparing the precursor of Mo2Ti2C3T x MXenes, 49wt% HF was used as etchant. First, a polytetrafluoroethylene beaker with holes was placed in a water bath. Then, 30 mL of HF was added to the polytetrafluoroethylene beaker using a pipette. Then, 2g of Mo2Ti2AlC3MAX phase was weighed and gradually added to the hydrofluoric acid solution, ensuring uniform dispersion of the powder, and finally a constant temperature water bath stirrer was started. The pre-etching process was carried out at 60℃ for 144 h, and the stirring speed was set to 500 r·min -1 After pre-etching, deionized water and high-speed centrifuge were used for cleaning until the pH value of the supernatant reached neutral.

[0070] (2) 3D-CNS was prepared by CVD method, and the specific method is as follows:

[0071] 3D-CNS was synthesized by CVD technology using ferrocene as catalyst and 1,2-dichlorobenzene as carbon source. First, ferrocene powder was dissolved in 1,2-dichlorobenzene to prepare a 0.03 g·mL-1 solution. Then, the solution was continuously fed into the quartz tube in the resistance furnace by an injection pump at a rate of 0.13 mL·min -1 . At a reaction temperature of 800 °C, a mixed gas of Ar and H2was used as the carrier gas, and the flow rates were set to 2000 mL·min -1 and 300 mL·min -1 , respectively. A piece of quartz was placed in the reaction zone as the growth substrate of 3D-CNS. After a growth process of 5 h, the 3D-CNS with a certain thickness was collected from the quartz substrate. The 3D-CNS was hydrothermally treated with concentrated nitric acid at 120 °C for 12 h, and then washed with deionized water until neutral to obtain 3D-CNS@Mo2Ti2C3T x MXene composite derivative.

[0072] (3) 3D-CNS@Mo2Ti2C3T x MXene composite derivative was prepared by electroplating and heat treatment process, and the specific method is as follows:

[0073] The prepared multilayer Mo2Ti2C3T x MXene solution was prepared into an electroplating solution of 1.5 M, and the ice bath probe was ultrasonically treated for 30 min. Then, the 3D-CNS treated with concentrated nitric acid was used as the electrode, and the metal platinum sheet was used as the counter electrode. The electroplating was carried out at a constant voltage of 15 V for 5 min. Then, the 3D-CNS@Mo2Ti2C3T x MXene composite derivative precursor substrate was freeze-dried and sintered at 500 °C for 2 h under the protection of inert gas. Example 5

[0074] A preparation method of 3D-CNS@Mo2Ti2C3T x MXene composite derivative, comprising the following steps:

[0075] (1) The multilayer Mo2Ti2C3T x MXenes were prepared by HF pre-etching of Mo2Ti2AlC3MAX phase.

[0076] The multilayer Mo2Ti2C3T x MXenes were prepared by liquid phase etching method, and the specific method is as follows:

[0077] The Mo2Ti2C3T xIn the precursor process of MXenes, 49wt% HF was used as the etchant. First, a polytetrafluoroethylene beaker with a hole was placed in a water bath. Then, 30 mL of HF was added to the polytetrafluoroethylene beaker using a pipette. Then, 2 g of Mo2Ti2AlC3 MAX phase was weighed and gradually added to the hydrofluoric acid solution, ensuring that the powder was evenly dispersed, and finally the constant temperature water bath stirrer was started. The pre-etching process was carried out at 60℃ for 144 h, and the stirring speed was set to 500 r·min -1 After the pre-etching was completed, deionized water and a high-speed centrifuge were used for cleaning until the pH value of the supernatant reached neutral.

[0078] (2) 3D-CNS was prepared by CVD method, and the specific method is as follows:

[0079] 3D-CNS was synthesized by CVD technology, using ferrocene as catalyst and 1,2-dichlorobenzene as carbon source. First, ferrocene powder was dissolved in 1,2-dichlorobenzene to prepare a 0.08 g·mL -1 solution. Then, the solution was continuously delivered into the quartz tube in the resistance furnace by the injection pump at a rate of 0.13 mL·min -1 . At a reaction temperature of 900℃, Ar and H2 mixed gas were used as carrier gas, and the flow rates were set to 2000 mL·min -1 and 300 mL·min -1 respectively. A piece of quartz sheet was placed in the reaction area as the growth substrate of 3D-CNS. After 5 h of growth process, 3D-CNS with a certain thickness was collected from the quartz substrate. The 3D-CNS was hydrothermally treated with concentrated nitric acid at 120℃ for 12 h, and then washed with deionized water until neutral to obtain 3D-CNS@Mo2Ti2C3T x self-supporting substrate of composite derivative of MXene.

[0080] (3) 3D-CNS@Mo2Ti2C3T x composite derivative of MXene was prepared by electroplating method and heat treatment process, and the specific method is as follows:

[0081] The prepared multilayer Mo2Ti2C3T x MXene solution was prepared into 1 M plating solution and ice bath probe ultrasonic for 30 min. Then, the 3D-CNS treated with concentrated nitric acid was used as the electrode, and the platinum sheet was used as the counter electrode. The electroplating was carried out at a constant voltage of 20 V for 5 min. Then, the 3D-CNS@Mo2Ti2C3T x composite derivative of MXene precursor substrate was freeze-dried and sintered at 500℃ for 2 h under inert gas protection. Comparative Example 1

[0082] This comparative example is the same as Example 1, except that in step (1), multilayer Mo2Ti2C3T x MXenes aqueous solution, without step (3), directly freeze-dried, then brush piece to assemble battery to test the electrical performance, the multilayer Mo2Ti2C3T x The specific capacity of the MXenes negative material for storing lithium is low, such as Figure 4 as shown. Comparative Example 2

[0083] This comparative example is the same as Example 1, except that in step (2), 3D-CNS is prepared, without step (3), directly cutting piece to assemble battery to test the electrical performance. The specific capacity of the 3D-CNS negative material for storing lithium prepared in step (2) is low, such as Figure 4 as shown.

[0084] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. 3D-CNS@Mo2Ti2C3T as a negative material for use in lithium-ion batteries x A method for preparing a composite derivative of MXene, characterized by, The preparation method comprises the following steps: (1) preparation of 3D-CNS Ferrocene is used as a precursor of catalyst, 1,2-dichlorobenzene is used as carbon source, and synthesis is carried out through chemical vapor deposition technology; (2) Multilayer Mo2Ti2C3T x Preparation of MXenes The multilayer Mo2Ti2C3T with different morphologies and yields is prepared by different process parameters through pre-etching with hydrofluoric acid x Mxenes; The specific process of pre-etching is as follows: Double-metal MAX phase precursor: Mo2Ti2AlC3 addition amount is 0.5 g-3 g; Etchant: 49 wt% HF, addition amount is 15 mL-40 mL; Pre-etching time: 120 h-168 h, to ensure sufficient pre-etching effect; Pre-etching temperature: 55℃-65℃, to optimize etching reaction; (3) 3D-CNS@Mo2Ti2C3T x Preparation of composite derivatives of MXene Acid treatment: using concentrated nitric acid for hydrothermal treatment of 3D-CNS, 120℃, 12 h, and using deionized water for washing to neutral; Electroplating solution: Multilayer Mo2Ti2C3T prepared x MXenes solution was prepared into 0.5-2 M electroplating solution, ice bath probe ultrasonic 30 min; Electroplating process: The concentrated nitric acid hydrothermal treated 3D-CNS as a flexible substrate, multilayer Mo2Ti2C3T x MXene solution was used as the electroplating solution, and platinum pieces were used as the counter electrode. The electroplating was carried out at a constant voltage of 3 V-20 V for 5 min-60 min. Heat treatment: 3D-CNS@Mo2Ti2C3T after electroplating is heated at 400-600 °C for 1-3 h under inert gas protection x The composite derivative precursor of MXene is freeze-dried, sintered at 400-600 °C for 1-3 h under inert gas protection, and an integrated self-supporting 3D-CNS@Mo2Ti2C3T is prepared x MXene composite derivative electrode The prepared 3D-CNS@Mo2Ti2C3T x The composite derivative of MXene, Mo2Ti2C3T x The electrochemically inactive M-X bond part in the MXene is effectively activated, effectively enriching the lithium storage sites of the derivative material, while synergistically inheriting and exerting the excellent electrical conductivity and good flexibility of the 3D-CNS, and further improving the lithium storage specific capacity of the derivative material at a large current density. The 3D-CNS@Mo2Ti2C3T x The composite derivative of MXene as a negative electrode material has a lithium storage capacity of 726 mAh / g in a lithium ion battery at a current density of 5 A / g.

2. The 3D-CNS@Mo2Ti2C3T of claim 1 x A method for preparing a composite derivative of MXene, characterized by, The specific process parameters of the step (1) 3D-CNS preparation are as follows: Solution preparation: Ferrocene powder was dissolved in 1,2-dichlorobenzene to prepare a solution with a concentration of 0.03-0.08 g-mL -1 -1. Solution delivery: The solution from the previous step was continuously injected into a quartz tube in a resistance furnace by a syringe pump at a rate of 0.1-0.2 mL min -1 -1. Reaction condition: the temperature in the furnace is set to 700-1000℃; Gas delivery: The mixed gas of argon and hydrogen was used as the carrier gas, and the flow rates were set to 2000 mL·min -1 and 300 mL·min -1 , respectively. Growth substrate: a 2 inch×1 inch quartz piece is placed in the reaction area as a growth substrate of carbon nanotube sponge; Collecting product: after 2-5 h of growth time, the three-dimensional carbon nanotube sponge with a certain thickness formed on the quartz substrate is collected.

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