Preparation method and application of manganese dioxide polyaniline MXene flexible composite material

Abstract

The invention discloses a preparation method and application of a manganese dioxide polyaniline MXene flexible composite material. Carbon cloth serves as a substrate, and the high-performance composite electrode material is prepared through the steps of polydopamine surface modification, MXene dipping adsorption, inert atmosphere calcination, polyaniline and manganese dioxide electro-deposition and the like in sequence. The preparation method has the beneficial effects that the material does not need to use a binder, effectively solves the compounding problem of the metal oxide, the conductive polymer and the metal carbide, remarkably improves the stability and the electrochemical performance of the electrode, is particularly suitable for preparation of the flexible supercapacitor electrode, and has important application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material preparation, and specifically relates to a preparation method and application of a manganese dioxide polyaniline MXene flexible composite material. Background Art

[0002] With the advancement of science and technology, growing awareness of environmental protection, and increasing energy demand, modern electronic products are becoming increasingly portable, flexible, and wearable. This creates an urgent need for the development of lightweight and flexible energy storage devices and related materials. Supercapacitors have attracted considerable attention due to their high power density, excellent cycling stability, outstanding flexibility, and rapid charge and discharge rates. Electrode materials, as their core component, directly determine the overall electrochemical performance of energy storage devices. Currently, the most widely studied electrode materials are carbon materials, metal compounds, and conductive polymers. Carbon materials offer high conductivity and high specific surface area, but low specific capacity. Conductive polymers, such as polyaniline and polypyrrole, have relatively high specific capacity but suffer from poor stability. Metal oxides, on the other hand, offer the highest theoretical specific capacity but exhibit lower conductivity.

[0003] Composite materials are composed of two or more materials with significantly different chemical or physical properties. In multi-component composites, each component provides unique functionality to optimize electrochemical performance. When combined, they can produce properties that differ from those of individual components, offsetting the shortcomings of individual components and synergizing their contributions to achieve greater advantages. In recent years, with the emergence of MXene materials, with their unique metallic conductivity and hydrophilicity, mechanical and optical properties, and through optimized structure and composite conductive materials, MXene can significantly improve energy density while also possessing advantages such as high conductivity, rich surface chemistry, and tunable interlayer spacing.

[0004] For example, the patent application number CN202211173240.2 discloses a MXene-based composite flexible electrode material and its preparation method, which x (MXene) dispersion and CNTs dispersion are alternately sprayed on a non-woven fabric substrate, dried, and carbonized under protective gas to obtain a MXene-based composite flexible electrode material.

[0005] Patent application number CN202411034039.5 discloses a MXene-based fiber flexible electrode material and a preparation method thereof, comprising: spinning an aramid nanofiber spinning solution through a wet spinning process to obtain ANF hydrogel fiber; placing the ANF hydrogel fiber in a single-layer MXene solution for impregnation to obtain MXene@ANF hydrogel fiber; vacuum drying the MXene@ANF hydrogel fiber to obtain a MXene@ANF fiber electrode material, that is, obtaining the MXene-based fiber flexible electrode material.

[0006] Patent application number CN201810544654.9 discloses a MnO2 / Ti3C2T x The preparation method of Mxene flexible supercapacitor electrode material is to obtain Ti3C2T by corroding the Al layer of Ti3AlC2 x , then MnCl2·4H2O and Ti3C2T x Mix and heat according to a certain mass ratio, and carry out redox reaction under the action of KMnO4, so that the generated MO2 nanorods are deposited on Ti3C2T x Finally, the flexible supercapacitor electrode material is obtained by washing and drying.

[0007] Although the above patents also provide some methods for preparing MXene-based flexible composite electrode materials, there are also problems such as complex processes and relatively single active components. Summary of the Invention

[0008] The purpose of the present invention is to overcome the defects of the prior art and provide a preparation method and application of a manganese dioxide polyaniline MXene flexible composite material.

[0009] The purpose of the present invention can be achieved through the following technical solutions:

[0010] A method for preparing a manganese dioxide polyaniline MXene flexible composite material comprises the following steps:

[0011] Step 1: Mix Ti3AlC2 powder with HCl / LiF solution and stir at 30-50°C for 20-48h. After the reaction liquid is centrifuged, acid-washed and washed with water several times until it is close to neutral, the precipitate is dissolved in ethanol and ultrasonicated, then centrifuged, washed with water, and centrifuged again. The upper layer of liquid is collected to obtain a MXene dispersion.

[0012] Step 2: Immerse the clean carbon cloth in a dopamine alkaline solution, adjust the pH to 8-10 with tris buffer, stir at room temperature for 2-24 hours, take out and wash with water and ethanol, and vacuum dry at 60-120°C to obtain polydopamine functionalized carbon cloth;

[0013] Step 3: Immerse the polydopamine-functionalized carbon cloth in the MXene dispersion for 1-100 minutes, remove it and dry it at 60-120°C, and repeat the above immersion-drying process 1-10 times to adjust the loading amount of MXene on the carbon cloth to obtain MXene-modified flexible carbon cloth;

[0014] Step 4: The MXene-modified flexible carbon cloth is placed in a furnace with an atmosphere of nitrogen or argon, and the temperature is raised to 400-900°C at a heating rate of 1-10°C / min and calcined for 1-10 hours to improve the conductivity of the composite material and effectively fuse and carbonize the polydopamine layer and the MXene adsorption layer to obtain a carbonized flexible carbon cloth;

[0015] Step 5: Polyaniline and manganese dioxide are sequentially deposited on the carbonized flexible carbon cloth by electrochemical deposition to obtain a manganese dioxide-polyaniline MXene flexible composite material.

[0016] More optimally, in the HCl / LiF solution, the molar ratio of HCl to LiF is 9:(1-2).

[0017] More optimally, the concentration of the dopamine alkaline solution is 0.5-8 g / L.

[0018] More optimally, the specific operation process of step 5 is:

[0019] (1) Using carbonized flexible carbon cloth as the working electrode, platinum sheet as the counter electrode, and saturated calomel electrode as the reference electrode, polyaniline was electrodeposited in a solution containing 0.1-1 M aniline and 0.1-1 M sulfuric acid using an electrochemical workstation;

[0020] (2) After rinsing the electrode after depositing polyaniline, the electrode was placed in a solution containing 0.01-1M manganese acetate and 0.05-1M sodium acetate to electrodeposit manganese dioxide. After washing with water, the electrode was vacuum-dried at 60-120°C to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0021] More optimally, the electro-deposition of polyaniline adopts cyclic voltammetry, with a deposition voltage of -0.5-1V, a scan rate of 1-100mV / s, and a deposition cycle of 1-30 cycles.

[0022] More optimally, the electrodeposition of manganese dioxide adopts a constant potential method, with a deposition voltage of 0.7-1.3 V and a deposition time of 100-3600 s.

[0023] More optimally, the manganese dioxide polyaniline MXene flexible composite material can be used to prepare flexible supercapacitors.

[0024] Beneficial effects:

[0025] The present invention uses carbon cloth as a substrate and sequentially produces a high-performance composite electrode material through the following steps: surface modification with polydopamine, MXene impregnation and adsorption, calcination in an inert atmosphere, and electrodeposition of polyaniline and manganese dioxide. This material, which requires no binder, effectively solves the complex composite problem of metal oxides, conductive polymers, and metal carbides, significantly improving the stability and electrochemical performance of the electrode. It is particularly suitable for the preparation of flexible supercapacitor electrodes and has important application value. The details are as follows:

[0026] First, through surface functionalization modification of polydopamine, the problem of conventional composite materials requiring binders for molding is solved, and the dispersion and bonding strength of MXene and other active substances on the surface of the flexible carbon cloth substrate are effectively enhanced. At the same time, subsequent high-temperature carbonization treatment of the polydopamine layer and the MXene adsorption layer can enhance the surface conductivity and composite effect.

[0027] Second: Polyaniline and manganese dioxide are deposited onto the surface of the modified flexible substrate by electrodeposition to obtain a ternary flexible composite material of MXene, manganese dioxide and polyaniline. This avoids the shortcomings of the active material layer prepared by conventional impregnation or hydrothermal methods, such as poor conductivity, poor structural stability, and uneven mixing and bonding by traditional coating methods. The stability and electrochemical activity of the composite material are effectively improved, and therefore it has broad application prospects in supercapacitor electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] Figure 1 The figure is a flow chart for the preparation of manganese dioxide polyaniline MXene flexible composite materials;

[0030] Figure 2 This is a scanning electron microscope image of the manganese dioxide polyaniline MXene flexible composite material according to Example 1 of the present invention;

[0031] Figure 3 CV curves of the manganese dioxide polyaniline MXene flexible composite material at different scan rates according to Example 1 of the present invention;

[0032] Figure 4 This is the GCD curve of the manganese dioxide / polyaniline / MXene flexible composite material of Example 1 of the present invention at different current densities. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] Pre-preparation: The preparation method of MXene solution is as follows:

[0035] To prepare MXene, 2g of LiF was weighed, along with 40mL of 9M HCl and 200mL of 1M HCl. The weighed LiF was poured into a reactor containing 40mL of 9M HCl and stirred at 500 rpm for 15 minutes. 2g of Ti3AlC2 was slowly added to the reactor and stirred at 35°C and 500 rpm for 48 hours. After etching, the supernatant was centrifuged at 4000 rpm for 5 minutes, and the supernatant was discarded. The resulting mixture was washed with 1M HCl and centrifuged at 4000 rpm for 3 minutes. After four centrifugations, the precipitate was collected and washed with deionized water, centrifuged at 4000 rpm for 3 minutes multiple times until the pH of the supernatant was >6. The lower precipitate was then re-dispersed with anhydrous ethanol, sonicated in an ice-water bath for 60 minutes, and then centrifuged at 10,000 rpm for five minutes. The supernatant was discarded. Next, the lower precipitate was redispersed in deionized water and centrifuged at 4000 r / min for 5 min. After centrifugation, the supernatant was collected to obtain the MXene solution.

[0036] Example 1: Cut a piece of 1×1.5cm carbon cloth, immerse it in 4g / L dopamine solution, adjust the pH value to about 8.5 by adding tris, and stir it at room temperature for 24h. Then take it out, rinse it with deionized water and ethanol, and dry it in a vacuum drying oven at 60℃; soak the carbon cloth in MXene solution for 15min and then dry it in an oven at 80℃, repeat the above steps 3 times; place the dried carbon cloth in an argon furnace and calcine it at 700℃ for 3h at a heating rate of 5℃ per minute; take out the carbon cloth and place it in a 0.8M MXene solution. In a mixed solution of aniline and 0.25M sulfuric acid, cyclic voltammetry was used for electrodeposition in an aniline acidic electrolyte solution using an electrochemical workstation. The deposition voltage range was between -0.2-0.7V, and the scan rate was 25mV / s, and the number of scans was 10. After taking out and rinsing, the carbon cloth was placed in a mixed solution containing 0.05M manganese acetate and 0.1M sodium acetate using a constant potential method. The deposition voltage was 0.9V and the deposition time was 600s. Then it was rinsed with water and vacuum dried at 80°C to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0037] Example 2: Cut a piece of 1×1.5cm carbon cloth, immerse it in 2g / L dopamine solution, adjust the pH value to about 8.5 by adding tris, and stir it at room temperature for 20h. Then take it out, rinse it with deionized water and ethanol, and dry it in a vacuum drying oven at 80℃; soak the carbon cloth in MXene solution for 10min and then dry it in an 80℃ oven. Repeat the above steps twice; place the dried carbon cloth in an argon furnace and calcine it at 600℃ for 2h at a heating rate of 2℃ per minute; take out the carbon cloth and place it in a 0.2M MXene solution. In a mixed solution of aniline and 0.2M sulfuric acid, cyclic voltammetry was used for electrodeposition in an aniline acidic electrolyte solution using an electrochemical workstation. The deposition voltage range was between -0.3-0.5V, and the scan rate was 15mV / s, and the number of scans was 15 circles. After taking out and rinsing, the carbon cloth was placed in a mixed solution containing 0.3M manganese acetate and 0.05M sodium acetate using a constant potential method. The deposition voltage was 0.7V and the deposition time was 500s. Then it was rinsed with water and vacuum dried at 80°C to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0038] Example 3: Cut a piece of 1×1.5cm carbon cloth, immerse it in 1g / L dopamine solution, adjust the pH value to about 8.5 by adding tris, and stir it at room temperature for 16h. Then take it out, rinse it with deionized water and ethanol, and dry it in a vacuum drying oven at 80℃; soak the carbon cloth in MXene solution for 20min and then dry it in an 80℃ oven. Repeat the above steps 3 times; place the dried carbon cloth in an argon furnace and calcine it at 500℃ for 3h at a heating rate of 4℃ per minute; take out the carbon cloth and place it in a 0.4M MXene solution. In a mixed solution of aniline and 0.8M sulfuric acid, cyclic voltammetry was used for electrodeposition in an aniline acidic electrolyte solution using an electrochemical workstation. The deposition voltage range was between -0.1-0.9V, and the scan rate was 20mV / s, and the number of scans was 10. After taking out and rinsing, the carbon cloth was placed in a mixed solution containing 0.5M manganese acetate and 0.7M sodium acetate using a constant potential method. The deposition voltage was 0.6V and the deposition time was 1000s. Then it was rinsed with water and vacuum dried at 80°C to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0039] Example 4: Cut a piece of 1×1.5cm carbon cloth, immerse it in 8g / L dopamine solution, adjust the pH value to about 8.5 by adding tris, and stir it at room temperature for 18h. Then take it out, rinse it with deionized water and ethanol, and dry it in a vacuum drying oven at 80℃; soak the carbon cloth in MXene solution for 15min and then dry it in an 80℃ oven. Repeat the above steps 4 times; place the dried carbon cloth in an argon furnace and calcine it at 650℃ for 1.5h at a heating rate of 8℃ per minute; take out the carbon cloth and place it in a 0 0.7M aniline and 0.2M sulfuric acid mixed solution, the electrochemical workstation in the aniline acidic electrolyte solution using cyclic voltammetry for electrodeposition, the deposition voltage range is between -0.3-0.6V, and the scanning rate is 30mV / s, the number of scanning circles is 15 circles; after taking out and rinsing, the carbon cloth is placed in a mixed solution containing 0.1M manganese acetate and 0.3M sodium acetate using a constant potential method, the deposition voltage is 1V and the deposition time is 400s, and then rinsed with water, and vacuum dried at 80 ° C to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0040] Example 5: Cut a piece of 1×1.5cm carbon cloth, immerse it in 5g / L dopamine solution, adjust the pH value to about 8.5 by adding tris, and stir it at room temperature for 10h. Then take it out, rinse it with deionized water and ethanol, and dry it in a vacuum drying oven at 80℃; soak the carbon cloth in MXene solution for 50min and then dry it in an oven at 80℃, repeat the above steps 4 times; place the dried carbon cloth in an argon furnace and calcine it at 650℃ for 3h at a heating rate of 5℃ per minute; take out the carbon cloth and place it in a 0.65℃ oven containing MXene. The carbon cloth was placed in a mixed solution of 0.1M aniline and 0.15M sulfuric acid, and cyclic voltammetry was used for electrodeposition in an aniline acidic electrolyte solution using an electrochemical workstation. The deposition voltage range was between -0.2-0.9V, and the scan rate was 25mV / s, and the number of scans was 15. After taking out and rinsing, the carbon cloth was placed in a mixed solution containing 0.1M manganese acetate and 0.2M sodium acetate using a constant potential method. The deposition voltage was 0.4V and the deposition time was 300s. Then it was rinsed with water and vacuum dried at 80°C to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0041] Comparative Example 1: Compared with Example 1, the polydopamine modification is lacking, as follows:

[0042] Cut a piece of 1×1.5cm carbon cloth, soak the carbon cloth in MXene solution for 15 minutes and then dry it in an 80℃ oven, repeat the above steps 3 times; place the dried carbon cloth in an argon furnace and calcine it at 700℃ for 3 hours at a heating rate of 5℃ per minute; take out the carbon cloth and place it in a mixed solution containing 0.8M aniline and 0.25M sulfuric acid, and use cyclic voltammetry to perform electrodeposition in aniline acidic electrolyte solution through an electrochemical workstation. The deposition voltage range is between -0.2-0.7V, and the scan rate is 25mV / s, and the number of scans is 10. After taking out and rinsing, the carbon cloth is placed in a mixed solution containing 0.05M manganese acetate and 0.1M sodium acetate using a constant potential method, the deposition voltage is 0.9V and the deposition time is 600s, then rinse it with water and vacuum dry it at 80℃ to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0043] Comparative Example 2: Compared with Example 1, the MXene solution was not immersed, and the details are as follows:

[0044] Cut a piece of 1×1.5cm carbon cloth, immerse it in 4g / L dopamine solution, adjust the pH value to about 8.5 by adding tris, and stir it at room temperature for 24h. Then take it out, rinse it with deionized water and ethanol, and dry it in a vacuum drying oven at 60℃. Place the dried carbon cloth in an argon furnace and calcine it at 700℃ for 3h at a heating rate of 5℃ per minute. After taking out the carbon cloth, put it into a mixed solution containing 0.8M aniline and 0.25M sulfuric acid, and electrochemically test it. The workstation was electroplated using cyclic voltammetry in an aniline acidic electrolyte solution with a deposition voltage range of -0.2-0.7 V and a scan rate of 25 mV / s for 10 scans. After taking out and rinsing, the carbon cloth was placed in a mixed solution containing 0.05 M manganese acetate and 0.1 M sodium acetate and subjected to a constant potential method with a deposition voltage of 0.9 V and a deposition time of 600 s. The cloth was then rinsed with water and vacuum dried at 80°C to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0045] Comparative Example 3: Compared with Example 1, the high-temperature calcination was not performed, and the details are as follows:

[0046] Cut a piece of 1×1.5cm carbon cloth, immerse it in 4g / L dopamine solution, adjust the pH value to about 8.5 by adding tris, and stir it at room temperature for 24h. Then take it out, rinse it with deionized water and ethanol, and dry it in a vacuum drying oven at 60℃; soak the carbon cloth in MXene solution for 15min and then dry it in an oven at 80℃. Repeat the above steps 3 times; take out the carbon cloth and put it into a mixed solution containing 0.8M aniline and 0.25M sulfuric acid. The workstation used cyclic voltammetry to perform electrodeposition in an aniline acidic electrolyte solution. The deposition voltage range was between -0.2 and 0.7 V, and the scanning rate was 25 mV / s, with a scanning number of 10 circles. After taking out and rinsing, the carbon cloth was placed in a mixed solution containing 0.05 M manganese acetate and 0.1 M sodium acetate. The constant potential method was used, and the deposition voltage was 0.9 V and the deposition time was 600 s. Then it was rinsed with water and vacuum dried at 80 ° C to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0047] Comparative Example 4: Compared with Example 1, polyaniline was not deposited, specifically as follows:

[0048] A 1×1.5 cm piece of carbon cloth was cut and immersed in a 4 g / L dopamine solution. The pH value was adjusted to about 8.5 by adding tris and stirred at room temperature for 24 h. Then it was taken out, rinsed with deionized water and ethanol, and dried in a vacuum drying oven at 60 °C. The carbon cloth was soaked in the MXene solution for 15 min and then dried in an 80 °C oven. The above steps were repeated 3 times. The dried carbon cloth was placed in an argon furnace and calcined at 700 °C for 3 h at a heating rate of 5 °C per minute. After taking out the carbon cloth, it was placed in a mixed solution containing 0.05 M manganese acetate and 0.1 M sodium acetate and subjected to a constant potential method with a deposition voltage of 0.9 V and a deposition time of 600 s. Then it was rinsed with water and vacuum dried at 80 °C to obtain a manganese dioxide polyaniline MXene flexible composite material.

[0049] Detection test:

[0050] (1) The microstructure of the manganese dioxide polyaniline MXene flexible composite material obtained in Example 1 was observed by scanning electron microscopy, and the results were as follows: Figure 2 As shown;

[0051] (2) Using a saturated calomel electrode as a reference electrode and a platinum sheet as an auxiliary electrode, the test was carried out in a 1M Na2SO4 solution electrolyte. The manganese dioxide polyaniline MXene flexible composite material obtained in Example 1 was tested using an electrochemical workstation. The voltage range was 0-0.6V, and the cyclic voltammetry (CV) curves at different scan rates were recorded. The results are shown in FIG. Figure 3 As shown;

[0052] (3) Using a saturated calomel electrode as a reference electrode and a platinum sheet as an auxiliary electrode, an electrochemical workstation was used to perform a constant current charge-discharge cycle performance test on the manganese dioxide polyaniline MXene flexible composite material obtained in the embodiment and the comparative example in a 1M Na2SO4 solution electrolyte. The voltage range was set to 0-0.8V, and the discharge time and other data at different current densities were recorded. The electrode specific capacitance at a current density of 1A / g was calculated according to the formula C=(I·Δt) / (m·ΔV) (C(F / g) represents the electrode specific capacitance, I(A) represents the discharge current, Δt(s) represents the discharge time, m(g) represents the active material, and ΔV(V) represents the voltage window range). The specific data are shown in the following table. In addition, the constant current charge-discharge (GCD) curve of Example 1 was also recorded, and the results are shown in the following table. Figure 4 shown.

[0053]

[0054] Table 1

[0055] Conclusion: The present invention achieves excellent electrochemical performance of the composite material through the synergistic effect of four key steps: polydopamine modification, MXene introduction, high temperature calcination and polyaniline deposition. Figure 2-Figure 4 It can be seen that the electrodeposition method makes the active material load very evenly on the surface of the electrode material, greatly increasing the contact area between the electrode material and the electrolyte solution. The MXene layer can enhance the bonding ability of polydopamine and MnO2 materials with the carbon cloth substrate. The calcined MXene layer can make the loading of the active material more uniform, playing a linking role during the composite, greatly improving the stability of the material; its CV curves at different scan rates and the constant current charge and discharge curves at different current densities have good symmetry, indicating that the composite material has good redox properties.

[0056] Furthermore, it can be seen from the comparison between the examples and the comparative examples (as shown in Table 1):

[0057] First, the absence of polydopamine (PDA) surface modification (Comparative Example 1) significantly reduces the electrochemical performance of the material. This is mainly because PDA modification can effectively enhance the bonding between the active material and the carbon cloth fiber. The lack of this step will lead to uneven distribution of the active material and weak bonding.

[0058] Secondly, the introduction of MXene active material is crucial (Comparative Example 2). As a highly conductive substrate, MXene can construct a three-dimensional conductive network, a property that compensates for the inherent defect of polyaniline's conductivity relying on doping. Experimental data confirms that the specific capacitance of materials lacking MXene decreases significantly.

[0059] Furthermore, the high-temperature calcination step (Comparative Example 3) plays a significant role in optimizing material properties. The calcination process not only improves the overall conductivity of the composite material but also makes the subsequent electrodeposition of polyaniline and manganese dioxide more uniform, effectively reducing intermolecular stacking.

[0060] Finally, the introduction of polyaniline (Comparative Example 4) plays a unique role. It can form a cross-linked network between the manganese dioxide particles, preventing them from agglomerating while also increasing the material's surface area, thereby providing more electrochemically active sites. The absence of this component also results in a significant decrease in specific capacitance.

[0061] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0062] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a manganese dioxide polyaniline MXene flexible composite material, characterized by: The steps include: Step 1: Mix Ti3AlC2 powder with HCl / LiF solution, stir at 30-50°C for 20-48h, centrifuge, wash, and ultrasonically disperse in ethanol, then take the supernatant to prepare MXene dispersion; Step 2: Immerse the clean carbon cloth in a dopamine alkaline solution, adjust the pH to 8-10, stir at room temperature for 2-24 hours, take it out, wash it with water and ethanol, and vacuum dry it at 60-120°C to obtain polydopamine functionalized carbon cloth; Step 3: Immerse the polydopamine-functionalized carbon cloth in the MXene dispersion for 1-100 minutes, remove it and dry it at 60-120°C, and repeat the above immersion-drying process 1-10 times to obtain MXene-modified flexible carbon cloth; Step 4: The MXene-modified flexible carbon cloth is heated to 400-900°C at a heating rate of 1-10°C / min under an inert atmosphere and calcined for 1-10 hours to obtain a carbonized flexible carbon cloth; Step 5: Polyaniline and manganese dioxide are sequentially deposited on the carbonized flexible carbon cloth by electrochemical deposition to obtain a manganese dioxide-polyaniline MXene flexible composite material.

2. The method for preparing a manganese dioxide polyaniline MXene flexible composite material according to claim 1, characterized in that: In the HCl / LiF solution, the molar ratio of HCl to LiF is 9:(1-2).

3. The method for preparing a manganese dioxide polyaniline MXene flexible composite material according to claim 1, characterized in that: The concentration of the dopamine alkaline solution is 0.5-8 g / L.

4. The method for preparing a manganese dioxide polyaniline MXene flexible composite material according to claim 1, characterized in that: The specific operation process of step 5 is as follows: (1) Using carbonized flexible carbon cloth as the working electrode, polyaniline was electrodeposited in a solution containing 0.1-1 M aniline and 0.1-1 M sulfuric acid; (2) After rinsing the electrode after depositing polyaniline, the electrode was placed in a solution containing 0.01-1M manganese acetate and 0.05-1M sodium acetate to electrodeposit manganese dioxide. After washing with water, the electrode was vacuum-dried at 60-120°C to obtain a manganese dioxide polyaniline MXene flexible composite material.

5. The method for preparing a manganese dioxide polyaniline MXene flexible composite material according to claim 4, characterized in that: The electro-deposition of polyaniline adopts cyclic voltammetry, with a deposition voltage of -0.5-1V, a scan rate of 1-100mV / s, and a deposition cycle of 1-30 cycles.

6. The method for preparing a manganese dioxide polyaniline MXene flexible composite material according to claim 4, characterized in that: The electrodeposition of manganese dioxide adopts a constant potential method, the deposition voltage is 0.7-1.3V, and the deposition time is 100-3600s.

7. A manganese dioxide polyaniline MXene flexible composite material, characterized by: Prepared according to the preparation method according to any one of claims 1 to 6.

8. Use of the manganese dioxide polyaniline MXene flexible composite material according to claim 7 in the preparation of flexible supercapacitors.

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