Radial structure MXene / waterborne polyurethane / cellulose-based nanofiber composite conductive aerogel sensing material and preparation method thereof

Abstract

The invention discloses an MXene / waterborne polyurethane / cellulose-based nanofiber composite conductive aerogel sensing material with a radial structure and a preparation method of the MXene / waterborne polyurethane / cellulose-based nanofiber composite conductive aerogel sensing material. The aerogel is prepared by taking a two-dimensional MXene nanosheet as a three-dimensional support framework and waterborne polyurethane as a cross-linking agent and combining liquid nitrogen radial freezing and freeze-drying processes, and has a special bionic radial structure. The vertical ordered radial structure of the aerogel is similar to a wall in a building, can provide strong support in the compression process, resists pressure stress through gradual bending deformation, and endows the aerogel with excellent mechanical properties. The piezoresistive sensor assembled by the aerogel has ultrahigh sensitivity, wide pressure detection range and excellent cycling stability, and can realize real-time monitoring of various complex movement and health signals of a human body.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible wearable electronic devices, in particular to a radial structure MXene / water-based polyurethane / cellulose-based nanofiber composite conductive aerogel sensing material and a preparation method thereof. BACKGROUND

[0002] With the vigorous development of Internet of Things, human-computer interaction and wearable electronic technology, multifunctional materials with super strong conductivity and good mechanical properties have become a new demand for flexible sensors. In recent years, lightweight elastic aerogels have become one of the most important candidate materials for developing high-performance multifunctional platforms due to their adjustable structure, low density and high porosity. MXene, as a new two-dimensional layered conductive nanosheet, has brought new breakthroughs to flexible sensing with its high conductivity (~20000 S / cm), rich surface terminal groups (-F, -OH, etc.) and good mechanical properties, and has gradually developed into a revolutionary pressure-sensitive material with great potential. However, the weak interlayer van der Waals force and poor gel ability of MXene nanosheets make it difficult to form a stable self-supporting structure, thereby greatly limiting its application potential as a high-performance flexible piezoresistive sensing active material.

[0003] For MXene composite aerogels, optimizing the internal microstructure and introducing appropriate cross-linking agents are the key to improving their mechanical properties and sensing performance. Studies have shown that the design of an ordered porous structure can enhance the mechanical stability of the composite aerogel, allowing it to better maintain structural integrity when subjected to external forces. For example, Ruoff et al. developed a radial freezing technique to assemble graphene oxide nanosheets into an ordered structure with vertical and radial arrangement, and the obtained aerogel showed higher mechanical strength and conductivity in the vertical direction compared to the non-oriented aerogel. In addition, introducing cross-linking agents (WPU, chitosan, sodium alginate, etc.) is another effective strategy to enhance the interaction force between MXene nanosheets. WPU is an environmentally friendly block polymer with water as the dispersion medium, composed of rigid hard segments and flexible soft segments, and has good flexibility and elasticity. When the unbound temperature is exceeded, the -NCO groups in the WPU molecular chain are released, which can cross-link with the hydroxyl groups on the surface of MXene to form a more compact and stable structure, providing an ideal material basis for the preparation of MXene composite aerogels. The synergistic optimization strategy based on structural design and cross-linking is expected to open up new ideas for the construction of high-performance piezoresistive sensing active materials. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a radial structure MXene / aqueous polyurethane / cellulose-based nanofiber composite conductive aerogel sensing material and a preparation method thereof to solve the problems of the prior art.

[0005] To achieve the above-mentioned application purposes, the technical scheme adopted by the present application is as follows: a radial structure MXene / aqueous polyurethane / cellulose-based nanofiber composite conductive aerogel sensing material and a preparation method thereof, comprising the following steps:

[0006] (1) synthesizing and preparing MXene nanosheets, the method comprising the following steps:

[0007] (1.1) adding lithium fluoride into a concentrated hydrochloric acid solution and stirring until the lithium fluoride is completely dissolved;

[0008] (1.2) slowly adding titanium aluminum carbide powder into the lithium fluoride / hydrochloric acid etching solution and stirring at 40 DEG C for 24 hours to obtain a stable suspension;

[0009] (1.3) performing cyclic centrifugal washing on the suspension in step (1.2) with deionized water until the supernatant pH is greater than or equal to 6;

[0010] (1.4) vacuum-assisted filtering the product in step (1.3) with deionized water as the medium, and then dispersing it in deionized water and performing ice bath ultrasonic treatment for 1 hour to obtain a Ti3C2TX MAX aqueous suspension;

[0011] (1.5) centrifuging the suspension obtained in step (1.4), collecting the suspension in a centrifuge tube, placing it in a-80 DEG C refrigerator, and then freeze-drying to obtain MXene nanosheets.

[0012] (2) weighing different cellulose derivative powders and dissolving them in a solvent, stirring, and preparing a spinning solution for storage;

[0013] (3) using an electrospinning technology to prepare a nanofiber membrane from the cellulose derivative spinning solution in step (2), and then placing it in an oven for drying and storage;

[0014] (4) dissolving and dispersing the dried MXene nanosheets in step (1) in deionized water and performing ultrasonic treatment, and then using an ultrasonic crusher to further homogenize and disperse to obtain an MXene dispersion liquid;

[0015] (5) The dried nanofiber film of step (3) is added to deionized water, and homogenized and dispersed by using a homogenizer to obtain a short nanometer dispersion liquid;

[0016] (6) The MXene dispersion liquid of step (4) and the short nanometer dispersion liquid of step (5) are mixed, and further dispersed by using an ultrasonic disrupter to obtain a MXene / short nanofiber mixed dispersion liquid;

[0017] (7) The mixed dispersion liquid of step (6) is added dropwise with aqueous polyurethane (WPU), stirred uniformly, and then radially frozen by using liquid nitrogen, followed by freeze-drying to obtain a MXene / WPU / cellulose derivative nanofiber composite conductive aerogel primary product.

[0018] (8) The MXene / WPU / cellulose derivative nanofiber composite conductive aerogel of step (7) is placed in a vacuum drying oven, heated and crosslinked for 5 hours to obtain a MXene / WPU / cellulose derivative nanofiber composite conductive aerogel sensing material.

[0019] Further, the concentration of hydrochloric acid in step (1.1) is 8-12 moles per liter, preferably 9 moles per liter.

[0020] Further, the time for adding titanium aluminum carbide to the lithium fluoride / hydrochloric acid etching solution in step (1.2) is controlled to be 6-12 minutes.

[0021] Further, the rotation speed of the cycle centrifugal washing in step (1.3) is 3000-4000 rpm, preferably 3500 rpm.

[0022] Further, the filter membrane used in the vacuum-assisted filtration process in step (1.4) is a hydrophilic PVDF polyvinylidene fluoride membrane (diameter of 70 mm, pore size of 220 nm) produced by Haishan Xindong Plastic Technology Co., Ltd.

[0023] Further, the ice bath ultrasonic in step (1.4) is performed by using an ultrasonic disrupter, and the ultrasonic power is 240 W.

[0024] Further, the freeze-drying in step (1.5) is performed at -90 to -45℃ and a pressure of 2-100 Pa, and the freeze-drying time is 24-48 hours.

[0025] Further, the cellulose derivative in step (2) is one of cellulose acetate, ethyl cellulose, and carboxymethyl cellulose.

[0026] Further, the concentration of the MXene dispersion liquid in step (4) is 4-12 mg / mL, preferably 8 mg / mL.

[0027] Further, the ultrasonic time in step (4) is 20-40 minutes; the ultrasonic crushing power is 240 W, and the time is 30-40 minutes.

[0028] Further, the concentration of the cellulose derivative nanofiber dispersion liquid in step (5) is 0.5 wt%, the speed of the homogenizer is 12000 rpm, and the time is 10-15 minutes.

[0029] Further, the MXene dispersion liquid and the cellulose derivative short nanometer dispersion liquid are mixed in a volume ratio of 1:1 in step (6).

[0030] Further, the water-based polyurethane used in step (7) is a water-based polyurethane produced by Anhui Andahuatai New Material Co., Ltd., with a model number of A105, a blocked-NCO content of 6.5±0.5%, and an unblocking temperature of 130°C or higher; the mass of the added water-based polyurethane is 5-80 mg.

[0031] Further, the directional freezing and freeze-drying method in step (7) is as follows: the MXene / WPU / cellulose derivative short nanofiber mixed solution is poured into a self-made mold (where the bottom is polytetrafluoroethylene and the upper part is a copper pipe), and then the mold is placed on a copper block in liquid nitrogen (the copper block is placed in liquid nitrogen and the upper surface is exposed) for directional freezing for 10-15 minutes to prepare a MXene / WPU / cellulose derivative nanofiber ice hydrogel; then the ice hydrogel is placed in a freeze dryer and dried at 2-100 Pa and -90°C for 48 hours to obtain a MXene / WPU / cellulose derivative nanofiber composite conductive aerogel primary product.

[0032] Further, the heating crosslinking temperature in step (8) is 130-150°C.

[0033] The beneficial technical effects of the present application are as follows:

[0034] (1) The present application uses two-dimensional MXene nanosheets as a three-dimensional support skeleton, water-based polyurethane as a crosslinking agent, and combines liquid nitrogen radial freezing and freeze-drying processes to prepare a MXene / WPU / cellulose derivative nanofiber composite conductive aerogel sensing material. The aerogel has a special radial structure, high conductivity, super elasticity, excellent fatigue resistance, and sensing performance. The piezoresistive sensor assembled with the aerogel has ultra-high sensitivity, a wide pressure detection range, and excellent cycle stability, and can realize real-time monitoring of various complex movements and health signals of the human body.

[0035] (2) The special self-made mold (the bottom is polytetrafluoroethylene, and the upper part is a copper pipe) used in the present application can realize the generation of a radial structure in liquid nitrogen freezing. The vertically arranged ordered radial structure is similar to the "wall" in a building, which provides strong support in the compression process and gradually bends and deforms to resist the compression stress, while effectively avoiding the aggregation and stacking of MXene materials, giving the aerogel excellent mechanical properties.

[0036] (3) A large number of short nanofibers are completely embedded in the pore wall like leaf veins, not only supporting the entire aerogel as a second skeleton, but also strengthening the pore wall structure with its vein-like structure, which plays an important role in improving the mechanical properties of the aerogel.

[0037] (4) The cellulose derivative nanofiber and the MXene sheet surface contain a large number of hydroxyl groups, which can crosslink with the isocyanate groups on the waterborne polyurethane (unblocking temperature is 130 DEG C) chain at a certain temperature, thereby further strengthening the binding force between the components of the aerogel and improving the resilience and fatigue resistance of the aerogel. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0039] Among them:

[0040] Figure 1 The preparation process schematic diagram of the two-dimensional MXene nanosheet described in the present application.

[0041] Figure 2 The mechanical property comparison chart of the composite conductive aerogel prepared in example 1, example 2 and comparative example of the present application.

[0042] Figure 3 The structure schematic diagram of the CA / MXene / WPU composite conductive aerogel prepared in example 2 of the present application and its corresponding SEM diagram (the scale is shown in the figure).

[0043] Figure 4The current-time diagram of human motion and physiological signal tested by the CA / MXene / WPU composite conductive aerogel prepared in Embodiment 2 of the present application after the flexible piezoresistive sensor is assembled; wherein Figure A is the assembled sensor testing finger clicking and pressing motion; Figure B is the assembled sensor fixed at the finger joint to test the finger bending motion; Figure C is the assembled sensor fixed at the elbow to test the elbow joint bending motion at different angles; Figure D is the assembled sensor fixed on the cheek to test the cheek blowing motion. Figures E and F are respectively the assembled sensor fixed at the wrist to test the pulse signal and its signal amplification diagram. DETAILED DESCRIPTION

[0044] In order to better understand the above-mentioned purposes, features and advantages of the present application, the specific embodiments of the present application will be described in detail below in combination with the drawings and specific embodiments.

[0045] The structures, proportions, sizes and the like shown in the drawings of the specification are only used to cooperate with the content disclosed in the specification, to be understood and read by those skilled in the art, and are not used to limit the conditions that the present application can be implemented, so they do not have technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effect and purpose that the present application can produce, should still fall within the scope of the technical content disclosed by the present application. At the same time, the terms such as "upper", "lower", "front", "rear", "middle" and the like in the specification are only for the convenience of clear description, and are not used to limit the scope of the present application, and the change or adjustment of the relative relationship, without substantially changing the technical content, is also considered as the implementation of the present application.

[0046] Secondly, "one embodiment" or "embodiment" referred to herein means that a certain feature, structure or characteristic can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is independent of or mutually exclusive with other embodiments.

[0047] Embodiment 1

[0048] A radial structure cellulose acetate / MXene composite conductive aerogel sensing material and a preparation method thereof, comprising the following steps:

[0049] (1) Synthetically prepare MXene nanosheets, the method comprising the following steps:

[0050] (1.1) Take 15.4 mL of 11.7 mol / L concentrated hydrochloric acid solution, add deionized water to 20 mL, prepare 9 mol / L hydrochloric acid solution, and save for later use.

[0051] (1.2) Weigh 1.6 g of lithium fluoride and dissolve it in the concentrated hydrochloric acid solution described in step (1.1), stir to ensure complete dissolution of the lithium fluoride, and prepare a LiF / HCl etching solution.

[0052] (1.3) Weigh 1 g of titanium aluminum carbide powder and slowly add it to the LiF / HCl etching solution described in step (1.2), and magnetically stir (550 rpm) at 40°C for 24 hours to obtain a stable suspension.

[0053] (1.4) Perform cyclic centrifugal washing (3500 rpm, 5 minutes per cycle) of the suspension described in step (1.3) with deionized water until the supernatant pH is ≥ 6.

[0054] (1.5) Vacuum-assisted filtration (using deionized water as the medium, with a usage of about 1 L) of the product described in step (1.3) is performed, with a filter membrane having a pore size of 220 nm, and then it is dispersed in deionized water and ultrasonically treated in an ice bath for 1 hour (240 W power) to obtain a Ti3C2TX MAX aqueous suspension.

[0055] (1.6) Centrifuge the suspension obtained in step (1.5) (3500 rpm, 5 minutes), collect the suspension in a centrifuge tube, freeze it in a -80°C refrigerator, and then freeze-dry it at -90°C and a pressure of 2 Pa for 24 hours to obtain MXene nanosheets.

[0056] (2) Weigh 2.7 g of cellulose acetate powder and dissolve it in a mixture of 10.38 mL of acetone and 4.65 mL of N,N-dimethylacetamide, stirring at a speed of 500 r / min to prepare a 18 wt% cellulose acetate spinning solution for storage.

[0057] (3) Spin the 18 wt cellulose acetate spinning solution described in step (2) in a high-voltage electrostatic field with a voltage of 15 kV, where the distance from the needle tip to the receiving roller is 15 cm, the pushing speed of the spinning solution is 1 mL / h, and the roller speed for collecting the fibers is 300 r / min. The temperature in the spinning closed environment is controlled at 25 ± 2°C, and the humidity is controlled at 50 ± 5%. After collecting the CA nanofiber membrane, place it in a 50°C drying oven for 24 hours.

[0058] (4) Weigh 80 mg of the dried MXene nanosheets described in step (1) and dissolve and disperse them in 10 mL of deionized water and ultrasonically treat for 30 minutes, and then further homogenously disperse them using an ultrasonic crusher (240 W power, 30 minutes) to prepare an MXene dispersion liquid;

[0059] (5) Take 0.1 g of the dried CA nanofiber film described in step (3) and cut into small pieces (1*1 cm), add 10 mL of deionized water, and use a homogenizer to homogenize at 12000 rpm for 15 minutes to prepare a CA short nanodispersion;

[0060] (6) Mix the MXene dispersion liquid described in steps (4) and (5) with the CA short nanodispersion, and use an ultrasonic crusher to further disperse (240 W power, 30 minutes) to prepare a CA-MXene mixed dispersion liquid;

[0061] (7) Transfer the CA-MXene mixed dispersion liquid described in step (6) to a self-made mold, freeze radially in a liquid nitrogen environment for 15 minutes, and then transfer to a freeze dryer to freeze dry at -90°C and 2 Pa pressure for 48 hours to obtain a CA / MXene composite conductive aerogel sensing material.

[0062] Example 2

[0063] A radial structure cellulose acetate / MXene / aqueous polyurethane composite conductive aerogel sensing material and a preparation method thereof, comprising the following steps:

[0064] (1) Synthetically prepare MXene nanosheets, the method is consistent with step (1) in Example 1.

[0065] (2) Take 3.6 g of cellulose acetate powder and dissolve it in 13.84 mL of a mixed solution of acetone and 6.2 mL of N,N-dimethylacetamide, stir and dissolve at a stirring speed of 500 r / min, and prepare 18 wt% cellulose acetate spinning solution for storage.

[0066] (3) Spin the 18 wt% cellulose acetate spinning solution described in step (2) in a high-voltage electrostatic field with a voltage of 15 kV, wherein the distance from the needle tip to the receiving roller is 15 cm, the pushing speed of the spinning solution is 1 mL / h, and the roller speed for collecting fibers is 300 r / min. The temperature in the spinning closed environment is controlled at 25±2°C, and the humidity is controlled at 50±5%. After collecting the CA nanofiber film, place it in a 50°C drying oven for 24 hours.

[0067] (4) Take 160 mg of the dried MXene nanosheet described in step (1) and dissolve and disperse it in 20 mL of deionized water and ultrasonic for 30 minutes, and then use an ultrasonic crusher for further homogenization and dispersion (240 W power, 30 minutes) to prepare a MXene dispersion liquid.

[0068] (5) Take 0.2 g of the dried CA nanofiber film described in step (3) and cut into small pieces (1*1 cm), add 20 mL of deionized water, and use a homogenizer to homogenize at 12000 rpm for 15 minutes to prepare a CA short nanodispersion.

[0069] (6) Mix the MXene dispersion described in steps (4) and (5) with the CA short nanodispersion, and use an ultrasonic disrupter to further disperse (240 W power, 30 minutes) to prepare a CA-MXene mixed dispersion.

[0070] (7) Add 20 mg of aqueous polyurethane (WPU) dropwise to the mixed dispersion described in step (6), stir until uniform, then transfer to a self-made mold, and perform radial freezing in a liquid nitrogen environment for 15 minutes, then transfer to a freeze dryer and freeze dry at -90°C, 2 Pa pressure for 48 hours to obtain a CA / MXene composite conductive aerogel primary product.

[0071] (8) Place the CA / MXene / WPU composite conductive aerogel described in step (7) in a vacuum drying oven, heat crosslinking at 150°C for 5 hours to obtain a CA / MXene / WPU composite conductive aerogel sensing material.

[0072] Comparative Example:

[0073] A composite conductive aerogel sensing material is prepared in accordance with the raw materials and preparation parameters used in Example 2 but without heat crosslinking treatment, and the structure and performance of the material are compared with the material of the present application, including the following steps:

[0074] (1) Synthesize and prepare MXene nanosheets in accordance with the method described in step (1) of Example 1.

[0075] (2) Take 3.6 g of cellulose acetate powder and dissolve it in 13.84 mL of acetone and 6.2 mL of N,N-dimethylacetamide mixed solution, stir at a stirring speed of 500 r / min to dissolve, and prepare a 18 wt% cellulose acetate spinning solution for storage.

[0076] (3) Spin the 18 wt% cellulose acetate spinning solution described in step (2) in a high-voltage electrostatic field with a voltage of 15 kV, where the distance from the needle tip to the receiving roller is 15 cm, the pushing speed of the spinning solution is 1 mL / h, and the roller speed for collecting fibers is 300 r / min. The temperature in the spinning closed environment is controlled at 25±2°C, and the humidity is controlled at 50±5%. After collecting the CA nanofiber film, place it in a 50°C drying oven for 24 hours.

[0077] (4) 160 mg of the dry MXene nanosheet described in step (1) was weighed and dissolved and dispersed in 20 mL of deionized water and ultrasonicated for 30 minutes, and then further homogenously dispersed by using an ultrasonic disrupter (240 W power, 30 minutes) to prepare a MXene dispersion.

[0078] (5) 0.2 g of the dry CA nanofiber film described in step (3) was weighed and cut into small pieces (1*1 cm), added to 20 mL of deionized water, and homogenized by using a homogenizer at 12000 rpm for 15 minutes to prepare a CA short nanodispersion.

[0079] (6) The MXene dispersion and the CA short nanodispersion described in steps (4) and (5) were mixed, and further dispersed by using an ultrasonic disrupter (240 W power, 30 minutes) to prepare a CA-MXene mixed dispersion.

[0080] (7) 20 mg of aqueous polyurethane (WPU) was added dropwise to the mixed dispersion described in step (6), stirred uniformly, and then transferred to a self-made mold, radially frozen in a liquid nitrogen environment for 15 minutes, and then transferred to a freeze dryer, and freeze-dried at -90°C and 2 Pa pressure for 48 hours to obtain a CA / MXene composite conductive aerogel sensing material.

[0081] Test Example:

[0082] Mechanical performance test: The parameters of the composite nanofiber aerogels prepared in Examples 1-2 and the comparative examples were recorded, and then a universal testing machine (UTM6502, Shenzhen Sanechips Technology Co., Ltd., China) was used to compress the aerogel samples at a speed of 10 mm / min, and the stress-strain curve was tested, and each sample was tested at least 3 times.

[0083] Piezoresistive sensing performance test: A piezoresistive sensing performance test was performed by using an electrochemical workstation (CHI660E, Shanghai Chenhua Instrument Co., Ltd.) combined with a universal testing machine. The CA / TPU / PPy composite conductive nanofiber aerogel prepared in Example 2 was assembled with copper tape and the like to prepare a simple device, the device was clamped by alligator clips and connected to the electrochemical workstation, and the conductivity and current response change of the material were observed and recorded.

[0084] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that a number of improvements and refinements can be made without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A radially structured MXene / waterborne polyurethane / cellulose-based nanofiber composite conductive aerogel sensing material and its preparation method, characterized in that, The preparation method includes the following steps: (1) Synthesis and preparation of MXene nanosheets: Lithium fluoride was slowly added to concentrated hydrochloric acid solution and stirred until homogeneous. Aluminum carbide powder was slowly added to the solution and stirred at 40°C for 24 hours to obtain a suspension. The suspension was washed by centrifugation (until the pH of the supernatant was ≥6). The precipitate was then vacuum-assisted filtered and dispersed in deionized water and sonicated. After centrifugation, the suspension was collected, frozen and freeze-dried to obtain MXene nanosheets, which were stored for later use. (2) Weigh the cellulose derivative powder and dissolve it in the corresponding solvent, stir, prepare the cellulose derivative spinning solution, and store it for later use; (3) The spinning solution described in step (2) is prepared into a nanofiber membrane using electrospinning technology, and then placed in an oven for drying and storage for later use. (4) Dissolve and disperse the dried MXene nanosheets obtained in step (1) in deionized water and perform ultrasonic treatment. Then, use an ultrasonic disruptor to further homogenize and disperse the MXene dispersion. (5) Add the dried nanofiber membrane described in step (3) to deionized water and homogenize and disperse it using a homogenizer to obtain a short nano-dispersion. (6) Mix the MXene dispersion obtained in steps (4) and (5) with the short nano dispersion, and further disperse it using an ultrasonic disruptor to obtain an MXene / cellulose derivative nanofiber mixed dispersion. (7) Add water-based polyurethane (WPU) dropwise to the mixed dispersion in step (6), stir evenly, and then perform radial freezing with liquid nitrogen. Subsequently, freeze-dry to obtain the initial product of MXene / WPU / cellulose derivative nanofiber composite conductive aerogel. (8) The MXene / WPU / cellulose derivative nanofiber composite conductive aerogel obtained in step (7) is placed in a vacuum drying oven and heated for cross-linking for 5 hours to obtain the MXene / WPU / cellulose derivative nanofiber composite conductive aerogel sensing material.

2. The preparation method according to claim 1, characterized in that, The concentration of hydrochloric acid in step (1) is 8-12 mol / L, and the time for adding titanium aluminum carbide to the lithium fluoride / hydrochloric acid etching solution is controlled at 6-12 minutes; the centrifugal washing speed of the suspension is 3000-4000 rpm, and the filter membrane used for vacuum-assisted filtration is a hydrophilic PVDF polyvinylidene fluoride membrane (diameter of 70 mm and pore size of 220 nm) produced by Haiyan Xindongfang Plastic Technology Co., Ltd.; the freeze drying is carried out at -90 to -45℃ and 2 to 100 Pa pressure for 24 to 48 hours.

3. The preparation method according to claim 1, characterized in that, The concentration of the MXene dispersion in step (4) is 4-12 mg / mL; the ultrasonic time for MXene is 20-40 minutes; the ultrasonic disruptor has a power of 240W and a time of 30-40 minutes.

4. The preparation method according to claim 1, characterized in that, The cellulose derivative mentioned in step (2) is one of cellulose acetate, ethyl cellulose, and carboxymethyl cellulose.

5. The preparation method according to claim 1, characterized in that, The concentration of the cellulose derivative nano-dispersion in step (5) is 0.5 wt%, the homogenizer speed is 12000 rpm, and the time is 10-15 minutes.

6. The preparation method according to claim 1, characterized in that, In step (6), the MXene dispersion and the short nano dispersion are mixed at a volume ratio of 1:

1.

7. The preparation method according to claim 1, characterized in that, The waterborne polyurethane used in step (7) is model A105 produced by Anhui Anda Huatai New Materials Co., Ltd., with a blocking-NCO content of 6.5±0.5% and an unblocking temperature of 130℃ or higher; the mass of the added waterborne polyurethane is 5 to 80 mg.

8. The preparation method according to claim 1, characterized in that, The directional freezing and freeze-drying method described in step (7) is as follows: the mixed solution of MXene / WPU / cellulose derivative nanofibers is poured into a self-made mold (the bottom is polytetrafluoroethylene and the top is a copper tube), and then the mold is placed on a copper block in liquid nitrogen (the copper block is placed in liquid nitrogen and the upper surface is exposed) and directionally frozen for 10-15 minutes to obtain MXene / WPU / cellulose derivative nanofiber ice gel; then the ice gel is placed in a freeze dryer and dried at 2-100 Pa and -90℃ for 48 hours to obtain the initial product of MXene / WPU / cellulose derivative nanofiber composite conductive aerogel.

9. The preparation method according to claim 1, characterized in that, The heating crosslinking temperature in step (8) is 130-150℃.

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