Two-dimensional mesoporous nanosheet composite, and preparation method and application thereof

Abstract

The application belongs to the technical field of electrode materials, and discloses a two-dimensional mesoporous nanosheet composite, a preparation method and application thereof, and the composite comprises single-layer uniform spherical mesoporous structures regularly arranged on two sides of MXene nanosheets, and the method comprises the following steps: (1) preparing a single-micelle solution; (2) preparing a 2-5 mg / mL MXene@micelle single-micelle superstructure alcohol solution; (3) preparing a composite of MXene@micelle single-micelle wrapped by polydopamine; (4) preparing a two-dimensional mesoporous nanosheet composite constructed by spherical mesoporous units; and application of the two-dimensional mesoporous nanosheet composite to batteries. The application greatly improves the specific surface area of the two-dimensional mesoporous nanosheet composite, increases active sites of chemical reactions, can provide better material transmission channels, and has fast mass transfer kinetics; and the assembled aqueous zinc ion battery has high discharge specific capacity and stable long cycle performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrode materials, more particularly, it relates to a two-dimensional mesoporous nanosheet composite and a preparation method and application thereof. BACKGROUND

[0002] As a new type of two-dimensional layered material, MXene material is mainly composed of transition metal carbides, nitrides and carbonitrides, thus laying a unique performance, such as high electrical conductivity, high mechanical strength, high chemical active surface and low cost, etc., so it has been widely concerned in the fields of mechanics, thermotics, electricity, magnetism and optics, but due to the van der Waals force and hydrogen bond between MXene nanosheets and the exposed metal atoms on the surface, it is easy to be oxidized and stacked. The introduction of mesoporous structure on the basis of two-dimensional material can not only improve its own defects, but also further improve the rich active sites of nanomaterial and accelerate the mass / electron transfer, greatly improve the reaction kinetics, and further increase the zinc ion energy storage performance.

[0003] The two-dimensional MXene mesoporous nanosheets prepared by traditional template-free method and hard template method mostly have few mesopores, and the pore size or arrangement is extremely irregular, which usually limits their practical application. Among them, the literature《Stabilizing atomic Co on 2D ordered mesoporous carbon sandwiched MXene for peroxymonosulfate activation: Enhanced performance and electron-transfer mechanism》disclosed a soft template method with micellar amphiphilic surfactant as template, although it can synthesize ideal two-dimensional mesoporous nanosheets, which has the advantages of multiple mesopores, pore size and arrangement, but the nanosheets obtained by this method usually have ring-shaped mesopores, which leads to the generation of super-long material transmission channel and extremely low mass transfer power, limiting its practical application. So far, the technology of synthesizing two-dimensional mesoporous nanosheets with spherical mesoporous structure has not been reported. Therefore, developing a method for synthesizing two-dimensional mesoporous nanosheet composite constructed by spherical mesoporous units is a synthetic hotspot and difficulty in the technical field. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application aims to provide a two-dimensional mesoporous nanosheet composite and a preparation method and application thereof, wherein the composite has a rich and special spherical mesoporous structure, greatly improving the specific surface area of the two-dimensional mesoporous nanosheet composite, increasing the active sites of chemical reaction, and providing a better material transmission channel with fast mass transfer power.

[0005] To achieve the above object, the present application provides the following technical scheme in one aspect: A preparation method of a two-dimensional mesoporous nanosheet composite, comprising the following steps:

[0006] (1) Dissolving an amphiphilic block copolymer micelle as a unit template in a solvent to obtain a block copolymer solution with a concentration of 0.1-40 mg / mL, and then preparing a single-micelle solution by a thermodynamic control method;

[0007] (2) Mixing the single-micelle solution in step (1) with a monolayer MXene alcohol dispersion solution with a concentration of 2-5 mg / mL and performing ultrasonic treatment, then adding an ammonia solution to perform oil bath stirring reaction, and after the oil bath stirring reaction, sequentially performing centrifugation, water washing, and anhydrous ethanol washing, and then redispersing in anhydrous ethanol to obtain a MXene@micelle single-micelle superstructure alcohol solution with a concentration of 2-5 mg / mL; wherein the volume ratio of the single-micelle solution, the monolayer MXene alcohol dispersion solution, and the ammonia solution is 3-6:1:0.025-0.03;

[0008] (3) Adding deionized water and bis-2-hydroxyethylamino trishydroxymethyl methane buffer to the MXene@micelle single-micelle superstructure alcohol solution in step (2) and performing ultrasonic treatment to make it uniformly dispersed; then adding polydopamine and stirring at room temperature to obtain a polydopamine-coated MXene@micelle single-micelle composite; wherein the mass ratio of the MXene@micelle single-micelle superstructure alcohol solution, the deionized water, the bis-2-hydroxyethylamino trishydroxymethyl methane buffer, and the polydopamine is 1:1-5:0.006-1:0.001-1;

[0009] (4) Sequentially performing centrifugation, washing, and drying on the MXene@micelle single-micelle composite in step (3), and then calcining under a nitrogen atmosphere to obtain a two-dimensional mesoporous nanosheet composite constructed by spherical mesoporous units.

[0010] Further, the block copolymer in step (1) is one or more of polystyrene-polytetraethylenylpyridine-polyethylene oxide, polystyrene-polyacrylic acid-polyethylene oxide, and polystyrene-polyethylene oxide.

[0011] Further, the solvent in step (1) is one or more of acetic acid, ethanol, water, DMF, or a mixture of DMF and water.

[0012] Further, in step (1), the thermodynamic control temperature is 20-110 ℃, and the time control is 0.5-10 h.

[0013] Further, in the step (2), the oil bath stirring reaction has a reaction temperature of 20-60 DEG C, a stirring speed of 500-1000 rpm, and a reaction time of 1-24 h; a centrifugal speed of 8000-15000 rpm, and water washing 3-6 times, and anhydrous ethanol washing 3-6 times.

[0014] Further, in the step (3), the stirring speed at room temperature is 500-800 rpm, and the reaction time is 1-100 h.

[0015] Further, in the step (4), the centrifugal speed is 8000-15000 rpm; the washing condition is that 95% ethanol solution is used for washing 3-6 times; and the drying condition is that the drying temperature is 20-60 DEG C, and the drying time is 2-24 h.

[0016] Further, in the step (4), the calcination is divided into two stages, the first stage has a calcination temperature of 350-400 DEG C and a calcination time of 1-10 h; and the second stage has a calcination temperature of 800-1000 DEG C and a calcination time of 1-10 h.

[0017] Another aspect of the present application provides the following technical solution: a two-dimensional mesoporous nanosheet composite, wherein single-layer uniform spherical mesoporous structures are regularly arranged on both sides of MXene nanosheets, the pore size of the spherical mesoporous structure is 22-46 nm, and the specific surface area of the two-dimensional mesoporous nanosheet composite is 387-156 m 2 / g.

[0018] Still another aspect of the present application provides the following technical solution: application of the two-dimensional mesoporous nanosheet composite in a battery, wherein the two-dimensional mesoporous nanosheet composite is used as a positive electrode, zinc sheets are used as negative electrodes, a water-based zinc salt electrolyte is used, and a water-based zinc ion battery is assembled.

[0019] The present application has the following advantages:

[0020] 1. The application discloses a two-dimensional mesoporous nanosheet composite and a preparation method thereof, wherein the two-dimensional mesoporous nanosheet composite is synthesized by a stable single-micelle assisted interfacial assembly method; that is, the MXene nanosheet surface is negatively charged, and the zeta potential measurement is -11.24 mV. The single-micelle shows a positive charge, and the zeta potential is 11.08 mV. Due to electrostatic attraction, the positively charged single-micelle can be closely anchored on the surface of the negatively charged MXene to form a closed micelle-MXene-micelle layered superstructure. Secondly, the polymerization of dopamine can not only be carried out on the single-micelle, but also on the MXene nanosheet surface. This is due to the coexistence of hydrogen bonds between the PEO end of the PS-PVP-PEO single-micelle and the -OH group and the -OH and -F end groups of the MXene nanosheet. The prepared two-dimensional mesoporous nanosheet composite has a rich and special spherical mesoporous structure, greatly improves the specific surface area of the two-dimensional mesoporous nanosheet composite, increases the active sites of chemical reactions, can provide better material transmission channels, and has a fast mass transfer dynamic.

[0021] 2. The application discloses an application of a two-dimensional mesoporous nanosheet composite, wherein a water-based zinc ion battery is assembled by taking the two-dimensional mesoporous nanosheet composite as a positive electrode, taking zinc sheets as a negative electrode and adopting a water-based zinc salt electrolyte, and the water-based zinc ion battery has a high discharge specific capacity and a stable long cycle performance. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A scanning electron microscope image of the two-dimensional mesoporous nanosheet composite prepared in Example 1.

[0023] Figure 2 An element mapping image of the two-dimensional mesoporous nanosheet composite prepared in Example 1.

[0024] Figure 3 A transmission electron microscope image of the two-dimensional mesoporous nanosheet composite prepared in Example 1.

[0025] Figure 4 A transmission electron microscope image of the two-dimensional mesoporous nanosheet composite prepared in Example 2.

[0026] Figure 5 A transmission electron microscope image of the two-dimensional mesoporous nanosheet composite prepared in Example 3.

[0027] Figure 6 A transmission electron microscope image of the two-dimensional mesoporous nanosheet composite prepared in Example 4.

[0028] Figure 7 A transmission electron microscope image of the two-dimensional mesoporous nanosheet composite prepared in Example 5.

[0029] Figure 8A specific capacity comparison chart of the batteries assembled for Examples 1-5 and Comparative Example 1.

[0030] Figure 9 A long cycle comparison chart of the batteries assembled for Examples 1-5 and Comparative Example 1. DETAILED DESCRIPTION

[0031] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0032] It should be noted that, unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0033] In the present application, unless otherwise stated, the orientation such as "upper, lower" is generally directed to the direction shown in the drawings, or is directed to the vertical, perpendicular or gravity direction; similarly, for the convenience of understanding and description, "left, right" is generally directed to the left and right shown in the drawings; "inner, outer" refers to the inner and outer relative to the contour of each component itself, but the above orientation words are not used to limit the present application.

[0034] Example 1: A method for preparing a two-dimensional mesoporous nanosheet composite, comprising the following steps:

[0035] (1) Using 80 mg of amphiphilic block copolymer polystyrene-polytetraethylene pyridine-polyethylene oxide (PS 106 -PVP 47 -PEO 113 ) micelles as a primitive template, dissolve it in 20 mL of acetic acid solution to obtain a block copolymer solution with a concentration of 20 mg / mL, keep the above solution at 110 ℃ for 3 hours, then cool to 25 ℃, and then put it into a dialysis bag for dialysis into a PS 106 -PV P47 -PEO 113 single-micelle deionized water solution;

[0036] (2) Add 1.5 mL of the single-micelle deionized water solution in step (1) dropwise to 0.5 mL of a monolayer MXene alcohol dispersion solution with a concentration of 3.5 mg / mL, and perform ultrasonic treatment, after 5 minutes of ultrasonic treatment, add 100 μL of ammonia solution for oil bath stirring reaction, i.e. stirring at 500 r / min in a 40 ℃ oil bath for 12 h, after the oil bath stirring reaction, sequentially undergo centrifugation at a speed of 12000 rpm, water washing 5 times, anhydrous ethanol washing 5 times, and then re-disperse in anhydrous ethanol to obtain a MXene@micelle single-micelle superstructure alcohol solution with a concentration of 4 mg / mL;

[0037] (3) 2 mL of deionized water was added to the MXene@micelle single-micelle superstructure alcohol solution in step (2) to form a uniformly dispersed solution, then 3 mg of bis-2-hydroxyethylamino trishydroxymethyl methane buffer was added to the solution, and ultrasonic treatment was performed to disperse it uniformly for 1 h; 3 mg of polydopamine was added, and the reaction was stirred at room temperature at a speed of 600 rpm for 12 h to obtain a polydopamine-wrapped MXene@micelle single-micelle composite;

[0038] (4) The MXene@micelle single-micelle composite in step (3) was sequentially subjected to centrifugation at a speed of 8000 r / min, then washed 5 times with 95% ethanol solution, then dried at a temperature of 50 ℃ for 18 h, and then calcined under a nitrogen atmosphere, i.e., heat-treated at 350 ℃ for 3 h to remove PS 106 -PVP 47 -PEO 113 micelles, and then the temperature was further increased to 800 ℃ for carbonization, and calcination was performed at this temperature for 3 h to obtain a two-dimensional mesoporous nanosheet composite constructed from spherical mesoporous units.

[0039] The two-dimensional mesoporous nanosheet composite prepared in Example 1 was observed for microstructure by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the element mapping of the two-dimensional mesoporous nanosheet composite prepared in Example 1 was determined, and the results are shown in Figure 1 、 Figure 2 and Figure 3 , Figure 1 、 2 and 3, it can be seen that the two-dimensional mesoporous nanosheet composite prepared in Example 1 has a surface with closely and regularly arranged superstructure protrusions, showing a rich and uniform spherical mesoporous structure, with a spherical mesoporous pore size of about 38 nm and a carbon layer thickness of about 8 nm. The specific surface area of the composite of Example 1 was measured by a full-automatic gas adsorption instrument, and the specific surface area of the two-dimensional mesoporous nanosheet composite was 260 m 2 / g.

[0040] Example 2: The overall method is the same as that of Example 1, except that the amphiphilic block copolymer is PS 69 -PVP 42 -PEO 113 .

[0041] The two-dimensional mesoporous nanosheet composite prepared in Example 2 was observed for microstructure by transmission electron microscopy (TEM), and the results are shown in Figure 4 .Figure 4 As can be seen, the surface of the two-dimensional mesoporous nanosheet composite prepared in Example 2 exhibits a densely and regularly arranged superstructure protrusion, displaying a rich and uniformly sized spherical mesoporous structure. The pore size of the spherical mesopores is approximately 22 nm, and the carbon layer thickness is approximately 8 nm. The specific surface area of ​​the composite in Example 2 was measured using a fully automated gas adsorption analyzer, and the specific surface area of ​​its two-dimensional mesoporous nanosheet composite was found to be 387 m². 2 / g.

[0042] Example 3: The overall method is the same as in Example 1, except that the amphiphilic block copolymer is PS. 216 -PVP 56 -PEO 113 .

[0043] The microstructure of the two-dimensional mesoporous nanosheet composite prepared in Example 3 was observed using transmission electron microscopy (TEM), and the results are as follows: Figure 5 As shown, by Figure 5 It can be seen that the surface of the two-dimensional mesoporous nanosheet composite prepared in Example 3 has tightly and regularly arranged superstructure protrusions, exhibiting a rich and uniformly sized spherical mesoporous structure. The pore size of the spherical mesopores is about 46 nm, and the carbon layer thickness is about 8 nm. The specific surface area of ​​the composite in Example 3 was measured by a fully automated gas adsorption analyzer, and the specific surface area of ​​its two-dimensional mesoporous nanosheet composite was found to be 156 m². 2 / g.

[0044] Example 4: A method for preparing a two-dimensional mesoporous nanosheet composite, comprising the following steps:

[0045] (1) Using 10 mg of the amphiphilic block copolymer polystyrene-polytetravinylpyridine-polyethylene oxide (PS) 106 -PVP 47 -PEO 113 Using micelles as the basic template, they were dissolved in 100 mL of acetic acid solution to obtain a block copolymer solution with a concentration of 0.1 mg / mL. This solution was kept at 20 °C for 0.3 hours, then cooled to 25 °C, and finally dialyzed in a dialysis bag to obtain PS. 106 -PV P47 -PEO 113 Single micelle deionized aqueous solution;

[0046] (2) 3 mL of the single micelle deionized water solution in step (1) was added dropwise to 1 mL of a single-layer MXene alcohol dispersion with a concentration of 2 mg / mL. The mixture was then sonicated. After sonication for 5 minutes, 0.025 μL of ammonia solution was added for oil bath stirring reaction. The mixture was stirred in an oil bath at 20 °C for 1 h at a speed of 750 r / min. After the oil bath stirring reaction, the mixture was centrifuged at a speed of 8000 rpm, washed with water 3 times, and washed with anhydrous ethanol 3 times. Then it was redispersed in anhydrous ethanol to obtain a MXene@micelle single micelle superstructure alcohol solution with a concentration of 2 mg / mL.

[0047] (3) Add 1 mL of deionized water to 1 mL of the MXene@micelle single micelle superstructure alcohol solution in step (2) to form a uniformly dispersed solution. Then add 0.006 mg of bis2-hydroxyethylaminotris(hydroxymethyl)methane buffer to the solution and sonicate it to disperse it evenly for 1 h. Then add 6 mg of polydopamine and stir at 800 rpm for 1 h at room temperature to obtain the polydopamine-encapsulated MXene@micelle single micelle complex.

[0048] (4) The MXene@micelle single micelle complex from step (3) was centrifuged at 12000 r / min, then washed three times with 95% ethanol solution, dried at 20 °C for 2 h, and then calcined under a nitrogen atmosphere, i.e., heat-treated at 370 °C for 1 h to remove PS. 106 -PVP 47 -PEO 113 The single micelle soft template was then carbonized at 900 °C and calcined at this temperature for 1 h to obtain a two-dimensional mesoporous nanosheet composite constructed from spherical mesoporous units.

[0049] The microstructure of the two-dimensional mesoporous nanosheet composite prepared in Example 4 was observed using transmission electron microscopy (TEM), and the results are as follows: Figure 6 As shown, by Figure 6 As can be seen, the two-dimensional mesoporous nanosheet composite prepared in Example 4 exhibits abundant and uniformly sized spherical mesoporous structures. The pore size of the spherical mesopores is approximately 38 nm, and the carbon layer thickness is approximately 20 nm. The specific surface area of ​​the composite in Example 4 was measured using a fully automated gas adsorption analyzer, and the specific surface area of ​​its two-dimensional mesoporous nanosheet composite was found to be 256 m². 2 / g.

[0050] Example 5: A method for preparing a two-dimensional mesoporous nanosheet composite, comprising the following steps:

[0051] (1) 80 mg of amphiphilic block copolymer polystyrene-poly(4-vinylpyridine)-poly(ethylene oxide) (PS-PVP-PEO) micelles were used as a primitive template, which was dissolved in 2 mL of acetic acid solution to obtain a block copolymer solution with a concentration of 40 mg / mL. The above solution was kept at 65 ℃ for 10 hours, and then cooled to 25 ℃, and then placed in a dialysis bag for dialysis to obtain a PS-PVP-PEO micelle deionized water solution. 106 -PVP 47 -PEO 113 106 -PV P47 -PEO 113

[0052] (2) 6 mL of the single-micelle deionized water solution in step (1) was added dropwise to 1 mL of a single-layer MXene alcohol dispersion solution with a concentration of 5 mg / mL, and ultrasonic treatment was performed. After 5 minutes of ultrasonic treatment, 0.03 μL of ammonia solution was added for oil bath stirring reaction, i.e. stirring at 1000 r / min in a 60 ℃ oil bath for 24 h. After the oil bath stirring reaction, centrifugation at a speed of 15000 rpm, water washing 6 times, and anhydrous ethanol washing 6 times were sequentially performed. Then, the MXene@micelle single-micelle superstructure alcohol solution with a concentration of 5 mg / mL was obtained by redispersion in anhydrous ethanol.

[0053] (3) 5 mL of deionized water was added to 1 mL of the MXene@micelle single-micelle superstructure alcohol solution in step (2) to form a uniformly dispersed solution. Then, 1 mg of bis-2-hydroxyethylamino trishydroxymethyl methane buffer was added to the solution, and ultrasonic treatment was performed to disperse the solution uniformly for 1 h. Then, 10 mg of polydopamine was added, and stirring reaction was performed at a speed of 500 rpm at room temperature for 100 h to obtain a polydopamine-wrapped MXene@micelle single-micelle composite.

[0054] (4) The MXene@micelle single-micelle composite in step (3) was sequentially subjected to centrifugation at a speed of 15000 r / min, and then washed 6 times with 95% ethanol solution. Then, drying was performed at a temperature of 60 ℃ for 24 h, and then calcination was performed at a temperature of 400 ℃ for 10 h under a nitrogen atmosphere to remove the PS-PVP-PEO single-micelle soft template. Then, the temperature was further increased to 1000 ℃ for carbonization, and calcination was performed at this temperature for 10 h to obtain a two-dimensional mesoporous nanosheet composite constructed by spherical mesoporous primitives. 106 -PVP 47 -PEO 113

[0055] ​​​The microstructure of the two-dimensional mesoporous nanosheet composite prepared in Example 5 was observed using transmission electron microscopy (TEM), and the results are as follows: Figure 7 As shown, by Figure 7 As can be seen, the two-dimensional mesoporous nanosheet composite prepared in Example 5 exhibits abundant and uniformly sized spherical mesoporous structures. The pore size of the spherical mesopores is approximately 38 nm, and the carbon layer thickness is approximately 30 nm. The specific surface area of ​​the composite in Example 2 was measured using a fully automated gas adsorption analyzer, and the specific surface area of ​​its two-dimensional mesoporous nanosheet composite was found to be 265 m². 2 / g.

[0056] The basic templates in Examples 1-3 are different. As the length of PS in the template increases, the pore size of the spherical mesopores in the resulting two-dimensional mesoporous nanosheet composites increases. The spherical mesopores in the two-dimensional mesoporous nanosheet composites prepared in Example 2 have the smallest pore size. The amount of polydopamine added in Examples 4-5 is increased compared to Example 1, which leads to an increase in the carbon layer thickness of the resulting two-dimensional mesoporous nanosheet composites with the increase of polydopamine addition.

[0057] Battery fabrication: First, the two-dimensional mesoporous nanosheet composites prepared in Examples 1-5 were mixed with conductive carbon black and polyvinylidene fluoride at a mass ratio of 8:1:1. Then, n-methyl-2-pyrrolidone solvent was added and the mixture was stirred for 5 hours to obtain a slurry. Next, the obtained slurry was coated onto a stainless steel foil as the positive electrode. Finally, the above positive electrode, zinc foil negative electrode, electrolyte (2 M ZnSO4-7H2O), and glass microfiber separator were assembled into a button cell (CR2025 type) for further testing.

[0058] Comparative Example 1: First, cyclic mesoporous nanosheets, conductive carbon black, and polyvinylidene fluoride (PVDF) from the prior art were mixed in a mass ratio of 8:1:1. Then, n-methyl-2-pyrrolidone solvent was added and the mixture was stirred for 5 hours to obtain a slurry. Next, the obtained slurry was coated onto a stainless steel foil as the positive electrode. Finally, the above positive electrode, zinc foil negative electrode, electrolyte (2 M ZnSO4-7H2O), and glass microfiber separator were assembled into a button cell (CR2025 type) for further testing.

[0059] Experiment: Charge-discharge tests were conducted on the aqueous zinc-ion batteries assembled in Examples 1-5 and Comparative Example 1, and the results are as follows. Figure 8 and Figure 9 As shown, by Figure 8 and 9 It can be seen that the battery prepared in Example 1 has a performance of 0.1 A g. -1 It has 158 mA hg -1 High specific capacity, and at a current density of 5 A g -1the battery prepared in Example 2 has a high specific capacity of 176 mA h g -1 at 0.1 A g -1 and the capacity retention rate thereof after 5000 cycles at a current density of 5 A g -1 is still 85%; the battery prepared in Example 3 has a high specific capacity of 130 mAh g -1 at 0.1 A g -1 and the capacity retention rate thereof after 5000 cycles at a current density of 5 A g -1 is still more than 82%; the battery prepared in Example 4 has a high specific capacity of 100 mA h g -1 at 0.1 A g -1 and the capacity retention rate thereof after 5000 cycles at a current density of 5 A g -1 is still more than 81%; the battery prepared in Example 5 has a high specific capacity of 105 mA h g -1 at 0.1 A g -1 and the capacity retention rate thereof after 5000 cycles at a current density of 5 A g -1 is still more than 84%; the battery prepared in Comparative Example 1 has a specific capacity of 80 mA h g -1 at 0.1 A g -1 and the capacity retention rate thereof after 5000 cycles at a current density of 5 A g -1 is only 70%; thus, the batteries assembled by the materials prepared in Examples 1-5 have much better performance than the battery prepared in Comparative Example 1, and the two-dimensional mesoporous nanosheet composite prepared in Example 2 has smaller pore size of the spherical mesoporous structure and higher specific surface area, resulting in more active sites for chemical reactions and better material transmission channels and fast mass transfer dynamics, so that the discharge specific capacity and long cycle performance of the battery assembled by the material prepared in Example 2 are the best among the other examples, and thus the two-dimensional mesoporous nanosheet composite prepared in the application has higher discharge specific capacity and more stable long cycle performance.

[0060] The preferred embodiments of the application are described above, but the application is not limited to the above, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

[0061] The above merely describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-described embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall also be considered as falling within the protection scope of the present application.

Claims

1. A method of preparing a two-dimensional mesoporous nanosheet composite, characterized by: It comprises the following steps: (1) Using amphiphilic block copolymer micelles as the basic template, dissolving it in a solvent to obtain a block copolymer solution with a concentration of 0.1-40 mg / mL, and then using a thermodynamic control method to prepare a single-micelle solution; The block copolymer is polystyrene-polytetraethylene pyridine-polyethylene oxide; (2) Mixing the single-micelle solution in step (1) with a monolayer MXene alcohol dispersion solution with a concentration of 2-5 mg / mL and performing ultrasonic treatment, then adding an ammonia solution for oil bath stirring reaction, and then sequentially performing centrifugation, water washing, and anhydrous ethanol washing, and then redispersing in anhydrous ethanol to obtain a MXene@micelle single-micelle superstructure alcohol solution with a concentration of 2-5 mg / mL; wherein the volume ratio of the single-micelle solution, the monolayer MXene alcohol dispersion solution, and the ammonia solution is 3-6:1:0.025-0.03; (3) Adding deionized water and bis-2-hydroxyethylamino trishydroxymethyl methane buffer to the MXene@micelle single-micelle superstructure alcohol solution in step (2) and performing ultrasonic treatment to make it uniformly dispersed; then adding polydopamine and stirring at room temperature to obtain a polydopamine-coated MXene@micelle single-micelle composite; wherein the mass ratio of the MXene@micelle single-micelle superstructure alcohol solution, the deionized water, the bis-2-hydroxyethylamino trishydroxymethyl methane buffer, and the polydopamine is 1:1-5:0.006-1:0.001-1; (4) The MXene@micelle single-micelle composite in step (3) is sequentially subjected to centrifugation, washing, and drying, and then calcination under a nitrogen atmosphere to obtain a two-dimensional mesoporous nanosheet composite constructed by spherical mesoporous units.

2. The method for preparing a two-dimensional mesoporous nanosheet composite according to claim 1, characterized in that: The solvent in step (1) is one or more of acetic acid, ethanol, water, DMF, or a mixture of DMF and water.

3. The method for preparing a two-dimensional mesoporous nanosheet composite according to claim 1, characterized in that: In step (1), the thermodynamic control temperature is 20-110℃, and the time control is 0.5-10 h.

4. The method for preparing a two-dimensional mesoporous nanosheet composite according to claim 1, characterized in that: In step (2), the oil bath stirring reaction temperature is 20-60℃, the stirring speed is 500-1000 rpm, the reaction time is 1-24 h, the centrifugal speed is 8000-15000 rpm, the water washing is 3-6 times, and the anhydrous ethanol washing is 3-6 times.

5. The method for preparing a two-dimensional mesoporous nanosheet composite according to claim 1, characterized in that: In step (3), the stirring speed at room temperature is 500-800 rpm, and the reaction time is 1-100 h.

6. The method for preparing a two-dimensional mesoporous nanosheet composite according to claim 1, characterized in that: In step (4), the centrifugal speed is 8000-15000 rpm; the washing condition is 3-6 times of washing with 95% ethanol solution; and the drying condition is a drying temperature of 20-60℃ and a drying time of 2-24 h.

7. The method for preparing a two-dimensional mesoporous nanosheet composite according to claim 1, characterized in that: In step (4), the calcination is divided into two stages, the first stage calcination temperature is 350-400℃, and the calcination time is 1-10 h; the second stage calcination temperature is 800-1000℃, and the calcination time is 1-10 h.

8. The two-dimensional mesoporous nanosheets composite prepared according to the preparation method of any one of claims 1-7, characterized in that: The two sides of the MXene nanosheet are regularly arranged with single-layer uniform spherical mesoporous structures, and the pore size of the spherical mesoporous structure is 22-46nm; the specific surface area of the two-dimensional mesoporous nanosheet composite is 387-156 m 2 / g.

9. Use of the two-dimensional mesoporous nanosheets composite of claim 8 in a battery, wherein The two-dimensional mesoporous nanosheet complex is used as a positive electrode, zinc sheets are used as negative electrodes, a water-based zinc salt electrolyte is used, and a water-based zinc ion battery is assembled.

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