A modified MXene conductive polymer bacterial cellulose composite fiber electrode, its preparation method and application

Abstract

This invention discloses a modified MXene conductive polymer-bacterial cellulose composite fiber electrode, its preparation method, and its applications, belonging to the field of composite conductive ultra-strong fiber preparation. The invention involves mixing K-MXene and a conductive polymer to obtain a composite conductive ink; subsequently, a strip-shaped BC hydrogel is crosslinked with the composite conductive ink via hydrogen bonds to obtain K-MXene / PEDOT:PSS@BC conductive hydrogel; next, the conductive hydrogel is subjected to wet-stretching and wet-twisting techniques to obtain K-MXene / PEDOT:PSS@BC conductive composite large fibers; finally, after PDMS dispersion impregnation coating and solvent replacement, a p-K-MXene / PEDOT:PSS@BC composite conductive large fiber electrode is obtained. The fiber electrode prepared by this invention can be woven with commercial yarns into smart fabrics for reliable detection of self-powered sensors and human body signals.

Description

Technical Field

[0001] This invention relates to a modified MXene conductive polymer bacterial cellulose composite fiber electrode, its preparation method and application, belonging to the field of composite conductive ultra-strong fiber preparation. Background Technology

[0002] In recent years, with the increasing demand for flexible wearable electronic devices, lightweight, portable, and wearable electrode materials have received widespread research attention for their applications in energy harvesting and storage, smart sensing, and smart connectivity. Compared to traditional rigid structural materials, fiber electrodes, due to their excellent mechanical strength, flexibility, and ease of integration, can be further woven with commercial fibers to form smart textiles, showing promising application prospects in the development of high-performance fiber-based supercapacitors, lithium / sodium-ion batteries, triboelectric / piezoelectric sensors, and other flexible electronic devices.

[0003] It is worth noting that fiber electrode materials are typically created by combining nano-conductive materials such as metals and their derivatives, carbon-based materials, conductive polymers, liquid electrodes, and mixed conductive materials with polymer substrates to obtain conductive fiber electrode structures. However, the stability of the multi-component mixed ink system determines the electrical properties of the conductive materials, thus affecting the overall performance of the fiber electrode materials. Current preparation methods mainly rely on simple mechanical mixing and complex post-processing, which may lead to uneven dispersion of conductive fillers and limitations in large-scale production. To address these issues, some researchers have been prompted to functionally modify conductive fillers to improve their colloidal stability and uniformity.

[0004] Titanium carbide (Ti3C2T) x MXene nanosheets possess metallic electrical properties, a typical layered structure, surface properties, and unique hydrophilicity, showing broad application prospects in multiple fields such as biosensing, energy storage, optoelectronics, and electromagnetic shielding. Furthermore, MXene is endowed with a large number of surface groups during hydrofluoric acid etching, resulting in excellent dispersibility in water. It can be processed into fibers or fabrics through various techniques such as spinning, coating, and printing. These properties and ease of processing have led to breakthroughs in the research of MXene-based functional fibers and smart textiles.

[0005] Bacterial cellulose (BC) is a high-purity cellulose synthesized by specific microorganisms (such as Staphylococcus aureus) under suitable culture conditions. It possesses ultra-high crystallinity, a nano-network structure, high mechanical strength, excellent biocompatibility, and water retention. In flexible electronic devices, introducing a certain proportion of bacterial cellulose into the system can endow the material with high mechanical strength and expand its applications in smart wearable fibers and smart fabrics. Currently, many conductive materials are combined with bacterial cellulose through doping, impregnation, and coating to prepare fiber materials that possess excellent mechanical properties and outstanding conductivity to meet practical application requirements.

[0006] Currently, some researchers are preparing triboelectric generators by combining conductive materials with cellulose; for example:

[0007] The literature (Fabric-Based TENG Woven with Bio-Fabricated Superhydrophobic Bacterial Cellulose Fiber) discloses the process of cutting, removing impurities, stretching, and twisting bacterial fiber membranes to form bacterial cellulose fibers; then impregnating them with carbon nanotube solution to form SEBC fibers, which are then woven to obtain triboelectric nanogenerators; however, the fiber electrode materials prepared by this method cannot well meet the Young's modulus requirements for fabric or device structure design and the stability of the device during wear; moreover, its conductivity and mechanical flexibility cannot be satisfied simultaneously.

[0008] The literature (Highly Conductive MXene / PEDOT:PSS-Integrated Poly(N-Isopropylacrylamide)Hydrogels for Bioinspired Somatosensory Soft Actuators) discloses the preparation of homogeneous and conductive hydrogel electrodes through in-situ copolymerization of conductive K-MXene / PEDOT:PSS ink and thermally responsive PNIPAM hydrogel. However, hydrogel electrodes are soft and contain water, making them highly susceptible to mechanical property degradation under stretching, drying, or shearing. Flexible electrode materials made from hydrogels are prone to drying, dehydration, and freezing, limiting their reliability in long-term use, field applications, or extreme climates. Furthermore, hydrogel electrode materials are mainly based on ion conductivity, and their slow ion migration rate and high impedance at high frequencies or low temperatures result in weak or delayed signals acquired by the bioelectrode. Summary of the Invention

[0009] [Technical Issues]

[0010] The conductive ink lacks stability;

[0011] The tensile strength of the fiber electrodes is mismatched.

[0012] Interface control between inorganic conductive materials and organic polymers is difficult;

[0013] Conventional fiber conductive materials have conductivity problems when bent, stretched and twisted.

[0014] [Technical Solution]

[0015] To address the aforementioned issues, this invention functionalizes MXene nanosheets (K-MXene) with KH570 and introduces conductive polymers (PEDOT:PSS, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid) to obtain K-MXene / PEDOT:PSS composite conductive ink. Subsequently, strip-shaped BC hydrogel crosslinks with the K-MXene / PEDOT:PSS composite conductive ink via hydrogen bonds to obtain K-MXene / PEDOT:PSS@BC conductive hydrogel. Next, the K-MXene / PEDOT:PSS@BC conductive hydrogel is processed using wet-stretching and wet-twisting techniques to obtain K-MXene / PEDOT:PSS@BC conductive large fibers. Finally, through PDMS dispersion impregnation coating and solvent replacement, a more dense pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode with ultra-high tensile strength and Young's modulus is obtained. The pK-MXene / PEDOT:PSS@BC composite conductive macrofiber prepared by this invention can be woven into smart fabrics with commercial yarns for reliable detection of self-powered sensors and human body signals.

[0016] The first objective of this invention is to provide a method for preparing a modified MXene conductive polymer-bacterial cellulose composite fiber electrode, comprising the following steps:

[0017] (1) K-MXene / PEDOT:PSS composite conductive ink

[0018] Titanium carbide (Ti3C2T) was obtained by in-situ chemical etching of Ti3AlC2 MAX phase powder. x MXene nanosheet aqueous dispersion;

[0019] In titanium carbide (Ti3C2T) x KH570 was added dropwise to an aqueous dispersion of K-MXene nanosheets to achieve full cross-linking, followed by centrifugation, washing, and collection of the precipitate. Water was then added to the precipitate to obtain the K-MXene dispersion system.

[0020] Then, PEDOT:PSS aqueous dispersion was added dropwise to the K-MXene dispersion system and stirred until homogeneous to obtain K-MXene / PEDOT:PSS composite conductive ink;

[0021] (2) K-MXene / PEDOT:PSS@BC composite conductive large fiber

[0022] The strip-shaped BC hydrogel was immersed in K-MXene / PEDOT:PSS composite conductive ink and then removed to obtain K-MXene / PEDOT:PSS@BC conductive hydrogel;

[0023] Subsequently, the K-MXene / PEDOT:PSS@BC conductive hydrogel was stretched and twisted in a wet state, and then dried under tension to obtain K-MXene / PEDOT:PSS@BC composite conductive macrofibers.

[0024] (3) pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode

[0025] The K-MXene / PEDOT:PSS@BC composite conductive large fiber was dipped into PDMS dispersion, removed, and dried to obtain the pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0026] In one embodiment of the present invention, the titanium carbide (Ti3C2T) in step (1) x Ti3C2T in aqueous solution of MXene nanosheets x The lateral dimensions of MXene nanosheets range from 100 nm to 50 μm, and the thickness of a single nanosheet ranges from 1 nm to 5 nm; the mass concentration ranges from 1 mg / mL to 20 mg / mL.

[0027] In one embodiment of the present invention, the ratio of Ti3AlC2 MAX phase powder to KH570 in step (1) is 2g:0.1-2mL.

[0028] In one embodiment of the present invention, the full crosslinking in step (1) is crosslinking at 20-30°C (room temperature) and 500-700 rpm for 20-30 hours.

[0029] In one embodiment of the present invention, the centrifugation in step (1) is performed at 6000-10000 rpm for 3-10 min.

[0030] In one embodiment of the present invention, the washing in step (1) is done with deionized water, and the number of washing cycles is 2 to 4.

[0031] In one embodiment of the present invention, the lateral dimension of K-MXene in step (1) is 100nm to 50μm, and the thickness of a single layer of K-MXene nanosheet is 2nm to 10nm.

[0032] In one embodiment of the present invention, the concentration of the PEDOT:PSS aqueous dispersion in step (1) is 1-2 wt%.

[0033] In one embodiment of the present invention, the stirring in step (1) is carried out at 20-30°C (room temperature) and 500-700 rpm for 6-24 hours for crosslinking.

[0034] In one embodiment of the present invention, the final concentration of K-MXene in the K-MXene / PEDOT:PSS composite conductive ink in step (1) is 8 to 20 mg / mL; and the final concentration of PEDOT:PSS is 4 to 20 mg / mL.

[0035] In one embodiment of the present invention, the strip-shaped BC hydrogel in step (2) is obtained by cutting the BC hydrogel. The size of the strip is (200-400) mm × (8-12) mm, the thickness is 2-4 mm, and the diameter is 50 nm to 100 nm.

[0036] In one embodiment of the present invention, the ratio of the amount of strip-shaped BC hydrogel and K-MXene / PEDOT:PSS composite conductive ink used in step (2) is 3g:20-40mL.

[0037] In one embodiment of the present invention, the immersion in step (2) is carried out at 6-8°C for 24-72 hours, which can be 24 hours, 48 ​​hours or 72 hours.

[0038] In one embodiment of the present invention, the wet stretching in step (2) is a tensile strain of 5% to 30%, which can be 5%, 10%, 20% or 30%.

[0039] In one embodiment of the present invention, in step (2), the wet twisting is performed at 1 to 20 rpm for 1 to 5 minutes; the twisting speed is 1, 5, 8, 10, 15 or 20 rpm; and the twisting time is 1 minute, 3 minutes or 5 minutes.

[0040] In one embodiment of the present invention, wet stretching and wet twisting in step (2) are achieved by mechanical clamping and applying axial tension and mechanical twisting.

[0041] In one embodiment of the present invention, the diameter of the K-MXene / PEDOT:PSS@BC composite conductive macrofiber in step (2) is 100-700 μm.

[0042] In one embodiment of the present invention, the PDMS dispersion in step (3) is a PDMS n-hexane dispersion with a concentration of 5wt% to 30wt%, which can be 5wt%, 10wt%, 20wt% or 30wt%.

[0043] In one embodiment of the present invention, the conditions for dipping the K-MXene / PEDOT:PSS@BC composite conductive large fiber into the PDMS dispersion in step (3) are: dipping at 20-30℃ (room temperature) for 5-15 minutes.

[0044] In one embodiment of the present invention, the drying in step (3) is drying at 20-30°C (room temperature).

[0045] In one embodiment of the present invention, the diameter of the pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode in step (3) is 100-700 μm.

[0046] The second objective of this invention is to prepare the pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode using the method described in this invention.

[0047] The third objective of this invention is the application of the pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode described herein in the field of flexible electronic devices such as high-performance fiber-based supercapacitors, lithium / nano-ion batteries, and triboelectric / piezoelectric sensors.

[0048] The fourth objective of this invention is to provide a triboelectric nanogenerator that employs the pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode described in this invention.

[0049] [Beneficial Effects]

[0050] Currently, most MXene-based composite fiber electrodes use one-dimensional nanowires, such as nanofiber dispersions, and carbon nanotubes or two-dimensional nanosheets, such as graphene, molybdenum disulfide, black phosphorus, or boron nitride nanosheets, as filling units, resulting in rigid structures. In contrast, PEDOT:PSS possesses high conductivity, flexibility, and transparency. Its molecular chains exhibit strong mobility, allowing the material to maintain conductivity even when bent, stretched, and twisted, making it an ideal functional nanofiller for flexible sensors and wearable fiber electrodes.

[0051] Therefore, this invention proposes using surface-functionalized MXene nanosheets as the basic material, preparing K-MXene / PEDOT:PSS conductive ink by introducing PEDOT:PSS, and employing in-situ self-assembly, wet stretching and twisting, and solvent displacement processes to prepare pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrodes with high tensile strength and Young's modulus through a synergistic strategy of hydrogen bonding and coordination bonds. This strategy can improve the orientation degree and ordered structure of the composite conductive fiber system, enabling fiber electrodes with high mechanical properties (tensile strength and Young's modulus).

[0052] This invention effectively enhances the inorganic-organic stable interface of pK-MXene / PEDOT:PSS@BC through a sequential bridging strategy of hydrogen bonds and coordination bonds. The pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode achieves a tensile strength of 435 MPa and a Young's modulus of 25.9 GPa. Simultaneously, the pK-MXene / PEDOT:PSS@BC exhibits a conductivity of 10.1 S / cm and an open-circuit voltage of 273 V, making it suitable for high-strength fiber electrodes in fiber-based triboelectric nanogenerators and flexible electronics. Attached Figure Description

[0053] Figure 1 This is a process flow diagram of the present invention.

[0054] Figure 2 Scanning electron microscope images of the microstructures of bacterial cellulose (BC) (a), K-MXene@BC (b), K-MXene / PEDOT:PSS@BC (c) and pK-MXene / PEDOT:PSS@BC (d) in Example 2; wide-angle X-ray scattering (WAXS) spectrum and corresponding azimuth curve of pK-MXene / PEDOT:PSS@BC composite fiber electrode after sequential crosslinking by hydrogen bonds and coordination bonds.

[0055] Figure 3 The mechanical properties of the pK-MXene / PEDOT:PSS@BC composite fiber electrode prepared in Example 2 are shown. Among them, the stress-strain curves (a), Young's modulus (b), and radar plot (c) of bacterial cellulose (BC), K-MXene@BC, K-MXene / PEDOT:PSS@BC and pK-MXene / PEDOT:PSS@BC conductive macrofibers are shown. The flexibility of pK-MXene / PEDOT:PSS@BC conductive macrofibers is shown (d). The fracture mechanism of pK-MXene / PEDOT:PSS@BC conductive macrofibers is shown (e).

[0056] Figure 4 The pK-MXene / PEDOT:PSS@BC composite fiber electrode prepared in Example 2 is used for the electrical output performance of a fiber-based triboelectric nanogenerator; wherein, (a) the open-circuit voltage between 1 and 4 Hz, (b) the short-circuit current, (c) the corresponding output voltage of triboelectric couples of different materials for specific identification of different materials, and (d) the output power density at a frequency of 3 Hz. Detailed Implementation

[0057] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0058] Test method:

[0059] The morphology of MXene, K-MXene and their composite conductive macrofibers was observed using a field emission electron microscope (FESEM SU8100).

[0060] The tensile strength and Young's modulus of the composite fiber were tested using a universal testing machine (INSTRON 1185).

[0061] The resistance of the composite fiber electrode was tested and the conductivity was calculated using an electrochemical workstation (CHI 660E).

[0062] The triboelectric output characteristics of the composite conductive macrofiber fabric were tested using an electrometer (Keithley 6514, Keithley Instruments, Inc.).

[0063] Raw materials used in the examples:

[0064] Ti3AlC2 MAX phase: 400 mesh, Jilin Yiyi Technology Co., Ltd.;

[0065] γ-Methacryloxypropyltrimethoxysilane: KH570, Aladdin Chemical Reagent Co., Ltd.;

[0066] Bacterial cellulose: BC, Guilin Qihong Technology Co., Ltd., bacterial cellulose length is 5-30μm;

[0067] Ti3C2T x The preparation method of MXene includes the following steps:

[0068] 3.2 g of lithium fluoride (LiF) powder was added to a polytetrafluoroethylene beaker containing 20 mL of 9 M hydrochloric acid (HCl), and the mixture was magnetically stirred at room temperature for 30 min until the powder was completely dissolved. 2.0 g of Ti3AlC2 MAX phase powder was slowly added to the above solution, and the mixture was stirred slowly at 50 °C for 48 h. The resulting solution was evenly dispersed into four centrifuge tubes, deionized water was added, and the mixture was centrifuged at 3500 rpm for 10 min. The supernatant was discarded, and the process was repeated until the pH of the supernatant was greater than 6. Then, 40 mL of anhydrous ethanol was added to the neutralized precipitate and the mixture was shaken well. The multilayer MXene was exfoliated by continuous sonication in a 350 W ice-water bath for 1 h. After centrifugation at 10000 rpm for 10 min, the precipitate was collected and dispersed in deionized water. The mixture was centrifuged at 3500 rpm for 3 min, and the centrifugation was repeated multiple times, collecting the supernatant. Water was added, and the volume was adjusted to 1000 mL to obtain the monolayer Ti3C2T. x MXene aqueous dispersion.

[0069] Ti3C2Tx MXene: Lateral dimensions range from 100 nm to 50 μm, and the thickness of a single-layer nanosheet ranges from 1 nm to 5 nm.

[0070] PEDOT:PSS aqueous dispersion: commercially available, 1.3 wt%; Anaiji Chemical.

[0071] Example 1

[0072] A method for preparing a modified MXene conductive polymer-bacterial cellulose composite fiber electrode includes the following steps:

[0073] (1) K-MXene / PEDOT:PSS composite conductive ink

[0074] Titanium carbide (Ti3C2T) was obtained by in-situ chemical etching of 2g of Ti3AlC2 MAX phase powder. x MXene nanosheet aqueous dispersion; the specific method is as described above;

[0075] In 1000 mL of titanium carbide (Ti3C2T) x In an aqueous dispersion of MXene nanosheets, 0.1 mL of KH570 was added dropwise under stirring at room temperature (500 rpm) until the entire amount was added. The mixture was stirred at room temperature (600 rpm) for 24 h to allow MXene and KH570 to fully crosslink. The mixture was then centrifuged at 6000 rpm for 10 min, washed three times with deionized water, and the precipitate was collected. Water was then added to the precipitate to obtain the K-MXene dispersion system.

[0076] Under stirring conditions at room temperature (500 rpm), 5.7 mL of 1.3 wt% PEDOT:PSS aqueous dispersion was added dropwise to the K-MXene dispersion system until the addition was complete. The mixture was then magnetically stirred at room temperature (600 rpm) for 6 h to obtain K-MXene / PEDOT:PSS composite conductive ink.

[0077] The final concentration of K-MXene was 20 mg / mL; the final concentration of PEDOT:PSS was 8.6 mg / mL; and the mass ratio of K-MXene to PEDOT:PSS was 7:3.

[0078] (2) K-MXene / PEDOT:PSS@BC composite conductive large fiber

[0079] Prepare BC hydrogel and cut it into strips with a size of 300mm × 10mm, a thickness of 3mm, and a BC diameter of approximately 50–100nm.

[0080] 3.0 g of strip-shaped BC hydrogel was immersed in 30 mL of K-MXene / PEDOT:PSS composite conductive ink and soaked at 7 °C for 72 h to obtain K-MXene / PEDOT:PSS@BC conductive hydrogel.

[0081] Next, the two ends of the K-MXene / PEDOT:PSS@BC conductive hydrogel were fixed to a twisting and stretching motor. The motor was used to perform wet stretching (tensile strain of 30%) and wet twisting treatment (3 min) at a speed of 8 rpm. The mixture was then dried under tension at room temperature to obtain K-MXene / PEDOT:PSS@BC conductive composite macrofibers with a diameter of 100-300 μm.

[0082] (3) pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode

[0083] K-MXene / PEDOT:PSS@BC composite conductive large fibers were dipped into a 10wt% PDMS n-hexane dispersion for 10 min at room temperature, then removed and dried at room temperature to obtain pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrodes (diameter 100-300 μm).

[0084] Example 2

[0085] Adjust the amount of KH570 used in step (1) of Example 1 to 1 mL;

[0086] Everything else remained the same as in Example 1, resulting in a pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0087] Example 3

[0088] Adjust the amount of KH570 used in step (1) of Example 1 to 2 mL;

[0089] Everything else remained the same as in Example 1, resulting in a pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0090] Example 4

[0091] The final concentration of K-MXene in step (1) of Example 2 was adjusted to 10 mg / mL; the final concentration of PEDOT:PSS was adjusted to 4.3 mg / mL; and the mass ratio of K-MXene to PEDOT:PSS was adjusted to 7:3.

[0092] Everything else remained the same as in Example 2, resulting in a pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0093] Example 5

[0094] The amount of PEDOT:PSS aqueous dispersion in step (1) of Example 2 was adjusted to 13.3 mL, so that the final concentration of K-MXene was 20 mg / mL; the mass ratio of K-MXene to PEDOT:PSS was 5:5;

[0095] Everything else remained the same as in Example 2, resulting in a pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0096] Comparative Example 1

[0097] In Example 2, the final concentration of K-MXene in step (1) was adjusted to 8.6 mg / mL; the final concentration of PEDOT:PSS was adjusted to 20 mg / mL; and the mass ratio of K-MXene to PEDOT:PSS was adjusted to 3:7.

[0098] Everything else remained the same as in Example 2, resulting in a pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0099] Comparative Example 2

[0100] The final concentration of K-MXene in step (1) of Example 2 was adjusted to 5 mg / mL;

[0101] Everything else remained the same as in Example 2, resulting in a pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0102] Comparative Example 3

[0103] The tensile strain of wet stretching in step (2) of Example 2 was adjusted to 5%, 10%, and 20%;

[0104] Everything else remained the same as in Example 2, resulting in a pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0105] Comparative Example 4

[0106] Adjust the wet twisting time in step (2) of Example 2 to 1 min and 5 min;

[0107] Everything else remained the same as in Example 2, resulting in a pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0108] Example 6

[0109] The concentration of the PMDS dispersion in step (3) of Example 2 was adjusted to 5, 20 and 30 wt%;

[0110] Everything else remained the same as in Example 2, resulting in a pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0111] Comparative Example 5

[0112] The PDMS dispersion impregnation step (3) in Example 2 is omitted;

[0113] Everything else remained the same as in Example 2, resulting in a K-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

[0114] Comparative Example 6

[0115] The mass ratio of PEDOT:PSS, K-MXene and PEDOT:PSS in step (3) of Example 2 is omitted, and the mass ratio of PEDOT:PSS to K-MXene is 1:0; the rest is the same as in Example 2, and a K-MXene / PEDOT:PSS@BC composite conductive large fiber electrode is obtained.

[0116] The performance of the obtained pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode was tested, and the test results are as follows:

[0117] Table 1

[0118]

[0119]

[0120] As can be seen from Table 1:

[0121] Comparative Example 1 shows that the prepared pK-MXene / PEDOT:PSS composite fiber electrode has low conductivity and cannot be applied in the field of fiber electrodes.

[0122] The pK-MXene / PEDOT:PSS composite fiber electrode prepared in Comparative Example 2 has low conductivity and cannot be applied to the field of fiber electrodes.

[0123] The insufficient wet stretching process in Comparative Example 3 resulted in a large amount of free water remaining inside the pK-MXene / PEDOT:PSS@BC gel, and the resulting pK-MXene / PEDOT:PSS@BC composite conductive macrofiber had a lower Young's modulus.

[0124] The sample prepared by wet twisting time of 1 minute in Comparative Example 4 had poor mechanical properties and lacked a uniform fiber structure; while the sample prepared by wet twisting time of 5 minutes showed over-twisting, the fibers were too hard and lost their softness, and a "back-twisting" phenomenon occurred, resulting in a rough hand feel and a high yarn breakage rate during subsequent weaving.

[0125] In Examples 2, 6, and Comparative Example 5, the static water contact angle of the PDMS dispersion with a concentration of 5 wt% was 127.4°; the static water contact angle of the PDMS dispersion with a concentration of 10 wt% (Example 2) was 145.4°; the static water contact angle of the PDMS dispersion with a concentration of 20 wt% was 144.5°; and the static water contact angle of the PDMS dispersion with a concentration of 30 wt% was 133°. It can be seen that the sample with a PDMS dispersion concentration of 10 wt% exhibited the most significant hydrophobic layer effect; however, as the PDMS dispersion concentration further increased, the static contact angle did not increase accordingly.

[0126] Figure 2 Scanning electron microscope (SEM) images of the microstructures of bacterial cellulose (BC) (a), K-MXene@BC (b), K-MXene / PEDOT:PSS@BC (c), and pK-MXene / PEDOT:PSS@BC (d) in Example 2; wide-angle X-ray scattering (WAXS) spectra and corresponding azimuth curves of the pK-MXene / PEDOT:PSS@BC composite fiber electrode after sequential crosslinking by hydrogen bonds and coordination bonds. Figure 2It can be seen that BC fibers exhibit obvious arc-shaped diffraction fringes, proving that the molecular chains are highly oriented along the fiber axis, indicating a high orientation parameter. The pK-MXene / PEDOT:PSS@BC composite fiber electrode scattering fringes are wider than those of BC fibers, indicating a lower degree of orientation. However, due to further impregnation with PDMS hexane, its orientation parameter is still superior to that of K-MXene@BC and K-MXene / PEDOT:PSS@BC fibers. The fracture morphology of the K-MXene / PEDOT:PSS@BC composite conductive fibers and pK-MXene / PEDOT:PSS@BC composite conductive fibers was tested using scanning electron microscopy. For the unimpregnated K-MXene / PEDOT:PSS@BC composite conductive fibers, the BC fiber bundles were stretched during the tensile process, showing significantly elongated BC fiber bundles at the fracture. Conversely, the pK-MXene / PEDOT:PSS@BC composite conductive fibers impregnated with PDMS exhibited micro-serrated fracture edges at the fracture surface, with an overall tightly packed fiber bundle structure, indicating high stress transfer efficiency between fiber bundles. Compared to uncoated K-MXene / PEDOT:PSS@BC, the pK-MXene / PEDOT:PSS@BC composite conductive macrofiber exhibits smaller fiber bundle elongation at the fracture surface. This is because the PDMS dispersion coating further reduces the bound water within the K-MXene / PEDOT:PSS@BC composite conductive macrofiber, resulting in a higher Young's modulus for the pK-MXene / PEDOT:PSS@BC composite conductive macrofiber. In contrast, the K-MXene / PEDOT:PSS@BC composite fiber electrode exhibits a lower Young's modulus and poorer deformability.

[0127] Figure 3 Mechanical properties of the pK-MXene / PEDOT:PSS@BC composite fiber electrode prepared in Example 2; wherein, (a) are the stress-strain curves of bacterial cellulose (BC), K-MXene@BC, K-MXene / PEDOT:PSS@BC and pK-MXene / PEDOT:PSS@BC conductive macrofibers; (b) are Young's modulus; (c) are radar plots; (d) are the flexibility demonstration of pK-MXene / PEDOT:PSS@BC conductive macrofibers; and (e) are the fracture mechanism of pK-MXene / PEDOT:PSS@BC conductive macrofibers. Figure 3It can be seen that BC and K-MXene@BC fibers exhibit high tensile strength, while K-MXene / PEDOT:PSS@BC exhibits a larger Young's modulus, proving that the molecular chain orientation increases after wet stretching and wet twisting of the large fiber bundles. In addition, SEM images show that the pK-MXene / PEDOT:PSS@BC conductive large fibers can be knotted without breaking, indicating their good flexibility and structural stability, making them suitable for flexible electronics and complex deformation applications.

[0128] Figure 4 The pK-MXene / PEDOT:PSS@BC composite fiber electrode prepared in Example 2 was used for the electrical output performance of a fiber-based triboelectric nanogenerator, wherein (a) the open-circuit voltage between 1 and 4 Hz; (b) the short-circuit current; (c) the corresponding output voltages of triboelectric couples made of different materials for specific identification of different materials; and (d) the output power density at a frequency of 3 Hz. Figure 4 It can be seen that the changes in open-circuit voltage and short-circuit current at frequencies ranging from 0.5Hz to 4Hz show that as the frequency increases, charge accumulation is faster, the charge transfer rate increases, and the output voltage and short-circuit current increase significantly. The open-circuit voltage increases from 155V to nearly 270V; the short-circuit current increases from 5μA to 18μA; and the output power density varies with the external load, reaching a maximum of 86.3mW / m. 2 The pK-MXene / PEDOT:PSS@BC-based fiber-based triboelectric nanogenerator outputs different voltages for different triboelectric materials (PVDF, PTFE, PET, PVC, Nylon, Cotton). Among them, the output voltage for PVDF is the highest, reaching 259.06V, and it has specific recognition.

[0129] Comparative Example 7

[0130] The K-MXene / PEDOT:PSS composite conductive ink in step (1) of Example 2 is adjusted as shown in Table 2; the rest remains the same as in Example 2.

[0131] The results are as follows:

[0132] Table 2

[0133] Material type Existing problems Comparison with MXene / PEDOT:PSS Graphene / PEDOT:PSS Poor dispersion and complex processing K-MXene / PEDOT; PSS exhibits better dispersion and a more homogeneous system. AgNWs / PEDOT:PSS High cost and easy oxidation K-MXene has lower cost and better stability. Pure PEDOT:PSS Limited conductivity MXene improves its electrical conductivity and mechanical properties. MXene Easily oxidized and has poor film-forming properties PEDOT: PSS improves its stability and processing performance.

[0134] Comparative Example 8

[0135] The strip-shaped BC hydrogel in step (1) of Example 2 was adjusted to (PVA / MXene / glycerol (Anti-Freezing, Conductive, and Strong Adhesive MXene-Based Hydrogel for Wearable Strain Sensors. ACS Applied Materials & Interfaces, 2021, 13(9), 10801–10811), with a strength of 200 kPa); other aspects remained the same as in Example 2.

[0136] The results showed that the obtained conductive hydrogel system had poor mechanical properties and could not meet the requirements of wearable systems with complex deformation.

[0137] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing a modified MXene conductive polymer-bacterial cellulose composite fiber electrode, characterized in that, Includes the following steps: (1) K-MXene / PEDOT:PSS composite conductive ink Titanium carbide (Ti3C2T) was obtained by in-situ chemical etching of Ti3AlC2 MAX phase powder. x MXene) nanosheet aqueous dispersion; in titanium carbide (Ti3C2T) x KH570 was added dropwise to the K-MXene nanosheet aqueous dispersion, and the mixture was fully crosslinked. After centrifugation and washing, the precipitate was collected. Water was then added to the precipitate to obtain the K-MXene dispersion system. PEDOT:PSS aqueous dispersion was then added dropwise to the K-MXene dispersion system and stirred until homogeneous to obtain the K-MXene / PEDOT:PSS composite conductive ink. (2) K-MXene / PEDOT:PSS@BC composite conductive large fiber The strip-shaped BC hydrogel was immersed in K-MXene / PEDOT:PSS composite conductive ink and then removed to obtain K-MXene / PEDOT:PSS@BC conductive hydrogel; Subsequently, the K-MXene / PEDOT:PSS@BC conductive hydrogel was stretched and twisted in a wet state, and then dried under tension to obtain K-MXene / PEDOT:PSS@BC composite conductive macrofibers. (3) pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode The K-MXene / PEDOT:PSS@BC composite conductive large fiber was dipped into PDMS dispersion, removed and dried to obtain the pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode.

2. The method according to claim 1, characterized in that, In step (1), the ratio of Ti3AlC2 MAX phase powder to KH570 is 2g:0.1~2mL.

3. The method according to claim 1, characterized in that, In step (1), the final concentration of K-MXene in the K-MXene / PEDOT:PSS composite conductive ink is 8-20 mg / mL; and the final concentration of PEDOT:PSS is 4-20 mg / mL.

4. The method according to claim 1, characterized in that, In step (2), the wet stretching involves a tensile strain of 5% to 30%.

5. The method according to claim 1, characterized in that, In step (2), the wet twisting is performed at 1-20 rpm for 1-5 minutes.

6. The method according to claim 1, characterized in that, In step (3), the PDMS dispersion is a PDMS-n-hexane dispersion with a concentration of 5wt% to 30wt%.

7. The method according to claim 1, characterized in that, In step (3), the diameter of the pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode is 100-700 μm.

8. The pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode prepared by the method according to any one of claims 1 to 7.

9. The application of the pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode as described in claim 8 in the field of flexible electronic devices such as high-performance fiber-based supercapacitors, lithium / nano-ion batteries, and triboelectric / piezoelectric sensors.

10. A triboelectric nanogenerator, characterized in that, The pK-MXene / PEDOT:PSS@BC composite conductive large fiber electrode as described in claim 8 was used.

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