MXene / wool keratin electrode and preparation method and application thereof

Abstract

The application discloses a kind of MXene / wool keratin electrode and its preparation method and application, including the following steps: with crosslinking keratin solution as core fluid, MXene dispersion liquid is as sheath fluid, coaxial spinning heat release dominant type fiber and weaving heat release layer;With the PI filament bundle of surface immersion MXene weaving transition layer and spraying miniature valve;With keratin solution as core fluid, MXene dispersion liquid is as sheath fluid, coaxial spinning electric storage dominant type fiber and weaving electric storage layer;Heat release layer, transition layer and electric storage layer are laminated and fixed in Z direction, fill polyvinyl alcohol / lithium chloride gel precursor, in situ phase change solidification obtains MXene / wool keratin electrode.The application realizes the deep cooperation of photo-thermal conversion and electrochemical energy storage by "differentiated functional fiber design+asymmetric three-dimensional braiding structure+double mechanism dynamic regulation", solves the problem of traditional device function fixed, low temperature failure, poor flexible adaptability.

Description

Technical Field

[0001] This invention relates to the field of functional fibers and flexible energy storage devices, specifically to an MXene / wool keratin electrode, its preparation method, and its application. Background Technology

[0002] With the rapid development of wearable electronic devices, the development of fabric electrodes that combine high energy density, excellent mechanical flexibility, and environmental adaptability has become a research hotspot. Transition metal carbides / nitrides (MXenes), with their metal-like conductivity, abundant surface functional groups, and excellent photothermal conversion capabilities, are considered ideal materials for constructing next-generation smart fabrics. Although the preparation of regenerated fibers using wet spinning technology and the construction of conductive fabrics through knitting or weaving processes have a certain technological foundation in the current technology, existing MXene-based flexible devices still have significant technical shortcomings in terms of multifunctional integration and adaptability to complex environments.

[0003] Taking patent CN115433434A as an example, although this existing technology adopts a three-dimensional braided structure, its design focuses on improving electromagnetic shielding and overall mechanical performance, with its internal fibers and functional fillers exhibiting a homogeneous distribution. This structure lacks differentiated layered design for the "thermal energy-electrical energy" transmission direction. In integrated photovoltaic-thermal-storage applications, due to the lack of an effective heat flow control mechanism, the high temperatures generated by photovoltaics and heat will diffuse indiscriminately in all directions, easily causing the electrolyte in the energy storage unit to dry out due to excessive temperature or triggering side reactions, thereby leading to device performance degradation or even failure.

[0004] Furthermore, while CN112593302A involves coaxial or helical fiber technologies that improve conductivity or strain performance at the individual fiber level, they fail to construct a macroscopically effective three-dimensional thermal management network. Such technologies lack an intermediate transition structure that combines electronic conduction and heat blocking, making it difficult to achieve directional and controlled heat transfer from the photothermal layer to the energy storage layer. In practical applications, this single-dimensional design results in poor device environmental adaptability: it cannot effectively lock in heat to maintain energy storage activity in extremely cold environments, while it cannot block excess heat under strong light.

[0005] In summary, existing technologies, relying solely on conventional material composites or textile processes, are insufficient to resolve the contradiction between the heat release from photothermal conversion and the temperature sensitivity of electrochemical energy storage. Therefore, there is an urgent need to develop a novel fabric electrode based on an asymmetric three-dimensional structural design and integrating an intelligent thermal management mechanism to meet the demands for efficient photothermal energy storage across all weather conditions and a wide temperature range. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing an MXene / wool keratin electrode, its preparation method, and its application. Through "differentiated functional fiber design + asymmetric three-dimensional braided structure + dual-mechanism dynamic regulation," it achieves deep synergy between photothermal conversion and electrochemical energy storage, solving the problems of fixed function, low-temperature failure, and poor flexibility of traditional devices.

[0007] To address the aforementioned technical problems, the first aspect of this invention provides a method for preparing an MXene / wool keratin electrode, comprising the following steps:

[0008] S1. Using the first cross-linked wool keratin solution as the core fluid, and the first MXene (Ti3C2T) as the core fluid. x The dispersion is a sheath fluid, and exothermic-dominant fibers are prepared by coaxial spinning. These exothermic-dominant fibers are then used to weave a high-density exothermic layer.

[0009] S2. A low-density transition layer is woven from polyimide (PI) filament bundles with MXene impregnation on the surface, and a thermally responsive micro-valve is sprayed onto the transition layer.

[0010] S3. Using the second wool keratin solution as the core fluid and the second MXene dispersion as the sheath fluid, a storage-dominant fiber is prepared by coaxial spinning. The storage-dominant fiber is used as the weft, and the storage-dominant fiber and carbon fiber filaments are used as the warp to weave a medium-density energy storage layer.

[0011] S4. The heat-releasing layer, transition layer and energy storage layer are sequentially stacked and fixed by Z-direction binding yarn, wherein the Z-direction binding yarn is made of polyimide filament bundle to form a woven fabric.

[0012] S5. Under vacuum negative pressure, polyvinyl alcohol (PVA) / lithium chloride (LiCl) gel precursor is filled into the woven fabric, and after in-situ phase change curing, the MXene / wool keratin electrode is obtained.

[0013] Both the exothermic-dominant and energy-storage-dominant fibers of this invention use wool keratin as the core layer and MXene as the sheath layer. The exothermic-dominant fiber uses cross-linked keratin, which has a dense structure and a stable (solid) gel network, and does not support rapid electrolyte penetration. It is mainly responsible for "heat generation" and "support" rather than ion storage. The energy-storage-dominant fiber uses cross-linked keratin. During regeneration in the coaxial spinning coagulation bath, the keratin chain segments rearrange, naturally forming vertically penetrating micropores of 5-20 μm, which increases the specific surface area for rapid insertion and extraction of electrolyte ions.

[0014] This invention constructs a three-layer asymmetric woven structure consisting of a heat-exothermic layer, a transition layer, and an energy storage layer, and combines it with a thermally responsive micro-valve intelligent control mechanism to achieve dynamic synergy between photothermal conversion and electrochemical energy storage functions.

[0015] Under strong light, the high concentration of MXene in the exothermic fiber sheath layer efficiently absorbs light energy and converts it into heat energy. As the temperature rises, the micro-valve in the transition layer undergoes a phase change and contracts, opening microporous channels and facilitating the directional transfer of heat to the energy storage layer via thermal convection / conduction. The heat entering the energy storage layer is absorbed by the PVA / LiCl gel electrolyte and the porous fiber framework, causing a local temperature increase. However, this temperature rise is not used for thermal energy storage or thermoelectric conversion, but rather utilizes the promoting effect of temperature on electrochemical kinetics: on the one hand, it reduces the viscosity of the gel electrolyte, and on the other hand, it increases the electrolyte ion concentration (LiCl). + The migration rate and adsorption / desorption rate of the battery are improved; this "photothermal-assisted" mechanism significantly reduces the electrochemical impedance, thereby enabling the battery storage layer to exhibit higher specific capacitance and charge / discharge efficiency under the same conditions.

[0016] In extremely cold / light-free environments: the micro-valve in the transition layer absorbs moisture and swells, increasing in volume to "close" and retain heat. Combined with an antifreeze PVA / LiCl gel electrolyte, this ensures the device doesn't freeze and can still discharge (solving the low-temperature failure problem). Simultaneously, using wool keratin and MXene composite fibers as basic units, combined with a PVA / LiCl antifreeze gel electrolyte (freezing point < -25℃), ensures the device's flexibility and electrochemical activity at extreme low temperatures from a material perspective. The gradient pores formed by the asymmetric braided structure effectively trap air, forming a thermal insulation buffer layer to further delay heat loss.

[0017] This invention uses waste wool as raw material to realize the high-value utilization of waste biomass resources and reduce raw material costs; it adopts a three-dimensional orthogonal weaving integrated molding process, combined with Z-axis polyimide bonded yarn, which ensures structural integrity while giving the electrode excellent flexibility and resistance to bending fatigue; it does not require complex and expensive equipment, the parameters are controllable and repeatable, and it is easy to realize continuous and large-scale production.

[0018] In this invention, the energy storage layer embeds carbon fiber filaments as a highly conductive and high-strength skeleton, which, together with porous energy storage-dominant fibers, constructs a planar conductive network. This serves both as an internal current collector to reduce interfacial resistance and as a mechanical reinforcement to improve the bending resistance and durability of the flexible electrode. Preferably, the ratio of energy storage-dominant fibers to carbon fiber filaments in the warp of the energy storage layer is (3-7):1.

[0019] Furthermore, in S1, the concentration of the first wool keratin solution is 12-15 wt%, and it is cross-linked with genipin; the concentration of the first MXene dispersion is 8-10 mg / mL.

[0020] And / or, during the coaxial spinning process, the flow rate ratio of the sheath fluid to the core fluid is (4-4.5):1.

[0021] Furthermore, in S2, the microvalve is prepared by mixing poly(N-isopropylacrylamide) and multi-walled carbon nanotubes, and then preparing composite gel microspheres with a diameter of 200-300 μm via reverse suspension polymerization, which serve as the microvalve. Utilizing the high thermal conductivity of carbon nanotubes, a highly efficient conductive network is constructed, significantly shortening the response time of the PNIPAM matrix to changes in ambient temperature. This overcomes the large thermal hysteresis inherent in traditional pure PNIPAM hydrogels, ensuring that the microvalve can achieve millisecond-level rapid opening and closing in response to changes in light intensity and ambient temperature.

[0022] The composite gel microspheres reduce their volume phase transition temperature to 15℃-18℃ through the salting-out effect. When the temperature of the energy storage layer is <15℃, the micro-valve absorbs moisture and swells, increasing in volume and blocking the pores, thus blocking heat transfer. When the temperature is >15℃ or the energy storage voltage is lower than the preset threshold (triggering an electrothermal response), the micro-valve undergoes a hydrophobic phase transition and shrinks (reducing in volume), thereby opening the blocked pores and opening the heat convection channel.

[0023] Furthermore, in S3, the concentration of the second wool keratin solution is 10-12 wt%, and the concentration of the second MXene dispersion is 4-6 mg / mL;

[0024] And / or, during the coaxial spinning process, the flow rate ratio of the sheath fluid to the core fluid is (2.5-3):1.

[0025] The present invention prepares a dense and thick sheath layer on the surface of the core layer of the heat-dominant fiber. The higher the MXene density, the higher the photothermal conversion efficiency and the more heat generated. The preparation of the energy storage-dominant fiber uses a low-concentration and low-flow-rate MXene dispersion sheath fluid, which prepares a thinner MXene layer and reduces the blockage of the pores inside the core layer.

[0026] Furthermore, the heat-dissipating layer has a weaving density of 10-12 threads / cm and a porosity of 50-55%; the transition layer has a weaving density of 4-6 threads / cm and a porosity of 80-85%; and the energy storage layer has a weaving density of 6-8 threads / cm and a porosity of 75-80%.

[0027] The heat-dissipating layer of this invention employs a densely woven "MXene sheath / crosslinked keratin core" composite fiber. The MXene sheath layer is responsible for efficiently absorbing sunlight and converting it into heat energy, serving as the heat energy supply source for the entire device. The dense structure acts as the "skin" of the device, preventing the internal electrolyte from leaking out or evaporating. The transition layer uses low-density woven MXene-coated polyimide (PI) filaments with embedded micro-valves, possessing high porosity (80-85%) and forming an air insulation layer. The micro-valves achieve "bidirectional dynamic control." The PI skeleton utilizes its low thermal conductivity to block heat conduction when the valves are closed, preventing overheating. When the heat-dissipating layer generates heat, the transition layer "opens" to conduct heat, using the heat to heat the electrolyte, allowing ions to move faster and significantly improving capacitance performance (light-enhanced energy storage), while simultaneously preventing excessive heat accumulation that could damage the device. The energy storage layer (skin-contact side) is made of loose porous weave. The loose structure adsorbs a large amount of electrolyte and provides ion transport channels. The carbon fiber filaments solve the problem of insufficient conductivity of keratin fibers and serve as current collectors. The high-concentration LiCl electrolyte ensures that it does not freeze at -20℃ and maintains basic working capacity.

[0028] Furthermore, in S4, the tension of the Z-direction binding yarn when it passes through and is fixed is 0.5-1.5N. Setting a small tension in the Z direction avoids excessive compression of the fabric thickness, ensuring strong interlayer bonding while maintaining low thermal conductivity.

[0029] Furthermore, in S5, the concentration of polyvinyl alcohol in the polyvinyl alcohol / lithium chloride gel precursor is 10-15 wt%, and the concentration of lithium chloride is 2-4 mol / L; the in-situ phase change curing is completed by a freeze-thaw cycle method.

[0030] Furthermore, between S4 and S5, the heat-dissipating layer undergoes a single-sided hot-pressing and polishing process to form a dense barrier layer on the surface of the heat-dissipating layer.

[0031] The second aspect of the present invention provides an MXene / wool keratin electrode prepared by the preparation method described in the first aspect.

[0032] The third aspect of the present invention provides the application of the MXene / wool keratin electrode described in the second aspect in wearable electronic devices.

[0033] The beneficial effects of this invention are:

[0034] This invention achieves deep synergy between photothermal conversion and electrochemical energy storage through "differentiated functional fiber design + asymmetric three-dimensional braiding structure + dual-mechanism dynamic control", solving the problems of fixed function, low-temperature failure and poor flexibility of traditional devices.

[0035] The MXene / waste wool keratin electrode prepared by this invention has outstanding advantages in terms of dynamic functional regulation, low-temperature stability, flexible wearability, green environmental protection and process feasibility. It is particularly suitable for fields with multiple requirements for energy management, such as outdoor emergency response, polar scientific research, and wearable electronic devices, and has broad prospects for industrial application. Attached Figure Description

[0036] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the heat dissipation layer, transition layer and energy storage layer stacked together according to the present invention;

[0038] The labels in the diagram are as follows: 1. Heat dissipation layer, 2. Transition layer, 3. Energy storage layer, 4. Micro valve, 5. Carbon fiber filament. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] This embodiment relates to a method for preparing an MXene / wool keratin electrode, comprising the following steps:

[0042] a. Preparation of functional fluids

[0043] (1) Preparation of waste wool keratin solution: Take waste wool fabric, cut it into pieces, and boil it in a 10wt% sodium hydroxide solution at 80℃ for 2 hours. After filtration, neutralize it with hydrochloric acid solution to a pH of 7. Put the obtained solution into a dialysis bag (molecular weight cutoff 8000-14000 Da) and dialyze it in deionized water for 3 days. Finally, concentrate the dialysate to prepare 15wt% and 10wt% keratin solutions for later use.

[0044] (2) Ti3C2T xPreparation of MXene aqueous dispersion: Ti3AlC2 MAX phase powder was slowly added to an HF / LiF mixed solution, and etched with stirring at 35°C for 24 hours. During this etching process, the aluminum (Al) atomic layer in the Ti3AlC2 precursor was selectively removed using in-situ generated hydrofluoric acid, disrupting the interlayer metallic bonds; simultaneously, lithium ions (Li...) in the solution... + The material is embedded in the interlayer space to increase the interlayer spacing and weaken the interlayer van der Waals forces. Subsequently, the product is centrifuged and washed until the pH of the supernatant is approximately 6. Then, it is ultrasonically exfoliated and centrifuged again to collect the supernatant, yielding Ti3C2T at concentrations of 8 mg / mL and 5 mg / mL, respectively. x MXene aqueous dispersion.

[0045] (3) Preparation of cross-linked keratin solution: Take 15wt% keratin solution, add 5% genipin of keratin content, and cross-link at 60℃ for 1 hour. The cross-linked keratin solution is used as the core fluid for preparing exothermic dominant fibers.

[0046] (4) Preparation of PVA / LiCl antifreeze gel precursor solution: Polyvinyl alcohol (PVA, type 1799) powder was added to deionized water and stirred at 90°C to dissolve, preparing a 12 wt% PVA aqueous solution. Subsequently, lithium chloride (LiCl) particles were added to the solution and stirred until completely dissolved, adjusting the molar concentration of LiCl to 3.0 mol / L.

[0047] (5) Preparation of thermally responsive micro valve precursor: Poly(N-isopropylacrylamide) monomer (PNIPAM) was mixed with multi-walled carbon nanotubes (MWCNTs) and composite gel microspheres with a diameter of 200-300 μm were prepared by reverse suspension polymerization.

[0048] b. Preparation and weaving of differentiated functional fibers

[0049] (1) Using coaxial microfluidic wet spinning technology, the cross-linked keratin solution prepared in step a(3) was used as the core fluid, and the 8 mg / mL MXene dispersion obtained in step a(2) was used as the sheath fluid. The sheath / core flow rate ratio was set to 4:1 (sheath flow rate 0.8 mL / h, core flow rate 0.2 mL / h), and spinning was performed in an ethanol / water (volume ratio 7:3) coagulation bath to obtain exothermic dominant fibers with a diameter of 300-500 μm. The exothermic dominant fibers were used as warp and weft yarns with an arrangement density of 10 yarns / cm and a tension controlled at 4 N to weave the exothermic layer.

[0050] (2) The PI filament bundle was immersed in 1 mol / L NaOH solution for 20 minutes, and then washed with deionized water until neutral. The treated PI filament bundle was immersed in 5 mg / mL MXene dispersion and the "immersion for 1 minute - drying" cycle was repeated 3 times to form the transition layer of braided fibers. The fibers were braided into a loose mesh at a density of 5 fibers / cm to form the transition layer. The thickness of the transition layer was about 150 μm and the porosity was about 82%. During the braiding process, the gel microspheres prepared in step a(4) were adhered and fixed at the intersection nodes of the transition layer fibers using a spraying process as micro valves.

[0051] (3) Using coaxial microfluidic wet spinning technology, the 10wt% uncrosslinked keratin solution prepared in step a(1) was used as the core fluid, and the 5mg / mL MXene dispersion in step a(2) was used as the sheath fluid. The sheath / core flow rate ratio was set to 3:1 (sheath flow rate 0.6mL / h, core flow rate 0.2mL / h). Spinning was carried out in an ethanol / water (volume ratio 7:3) coagulation bath, and the fibers were regenerated and shaped in the coagulation bath to form a storage-dominant fiber with a porous structure of 5-20μm in the internal core layer. The storage-dominant fiber was used as the weft yarn, and the storage-dominant fiber and graphitized carbon fiber filaments were used as the warp yarns. The "mixed weaving" process was adopted. In the warp yarns, the ratio of the number of storage-dominant fibers to graphitized carbon fiber filaments was 5:1. The carbon fiber filaments were used as conductive reinforcing warp yarns with a tension of 2N, and the tension of the storage-dominant fiber was controlled at 3N. The overall arrangement density was 6 fibers / cm.

[0052] c. For example Figure 1 As shown, a heat-generating layer 1, a transition layer 2, and a power storage layer 3 are stacked. A micro-valve 4 is adhered and fixed to the transition layer 2, and carbon fiber filaments 5 are embedded in the power storage layer 3. Polyimide filament bundles are selected as the Z-direction binding yarn. This Z-direction yarn penetrates the heat-generating layer, transition layer, and power storage layer along the thickness direction during weaving, interlocking and fixing the three layers. To preserve the porous and loose structure of the power storage layer, the tension of the Z-direction yarn is set to 1N (lower than the warp and weft tensions).

[0053] d. Post-processing and in-situ gelation encapsulation

[0054] (1) Single-sided densification: The heat-dissipating layer of the woven fabric is subjected to single-sided hot pressing and calendering treatment at 80°C and 0.5 MPa to form a dense barrier layer on its surface.

[0055] (2) Vacuum-assisted liquid injection: The fabric is inverted (i.e., the heat-generating layer is facing down and the energy storage layer is facing up) and laid flat in a polytetrafluoroethylene (PTFE) molding mold. The mold has grooves that match the size of the fabric and are about 500 μm deep. Since the energy storage surface is loosely woven, the interconnected pores formed at the interlacing of the fibers are the liquid injection microchannels. The PVA / LiCl precursor solution in a molten state at 90℃ is directly coated on the surface of the energy storage layer. Under the action of vacuum negative pressure, the precursor solution quickly penetrates and fills the transition layer along these vertical microchannels. The vacuum negative pressure is used to fully wet the fibers inside the energy storage layer and the transition layer. The heat-generating layer at the bottom has been densified, which effectively prevents solution leakage. The impregnated electrode is placed in a -20℃ environment and frozen for 12 hours, and then thawed at room temperature for 2 hours. This cycle is repeated 3 times (i.e., the freeze-thaw cycle method) so that the precursor solution physically crosslinks in situ in the fiber gaps to form a quasi-solid gel, thus obtaining the MXene / wool keratin electrode. At this point, the electrolyte has transformed into a non-flowing gel state and formed an integrated interpenetrating network with the fiber skeleton, thus completely resolving the leakage concern.

[0056] Example 2

[0057] The difference between this embodiment and Embodiment 1 lies in the preparation parameters and weaving density of the functional fibers, in order to explore the influence of different parameters on performance, specifically:

[0058] Exothermic-dominant fibers: The concentration of MXene dispersion in the sheath layer was increased to 10 mg / mL, and the sheath / core flow rate ratio was set to 4.5:1;

[0059] Energy-storage-dominant fiber: The concentration of the core layer fluid keratin solution was adjusted to 12wt%.

[0060] The braiding density of the heat-dissipating surface is increased to 12 strands / cm, the braiding density of the energy storage surface is increased to 8 strands / cm, the braiding density of the transition layer is adjusted to 4 strands / cm, and the porosity changes accordingly to 85%.

[0061] The other preparation steps and parameters are the same as in Example 1.

[0062] Comparative Example 1

[0063] The difference between this comparative example and Example 1 is that a symmetrical structure electrode without a heat-exothermic layer and a transition layer is prepared. Specifically, only the energy storage-dominant fiber prepared in Example 1 is used, and the energy storage surface is woven into a single-layer fabric electrode with a total thickness equivalent to that in Example 1, referring to the weaving process of the energy storage surface in Example 1 (6 fibers / cm density, embedded graphitized carbon fiber filaments). Subsequently, the same process is used to inject a PVA / LiCl precursor solution and freeze-cur in situ.

[0064] Comparative Example 2

[0065] The difference between this comparative example and Example 1 is that...

[0066] The waste wool keratin solution in Example 1 was completely replaced with a polyacrylonitrile (PAN) solution of equal concentration; and the PVA / LiCl antifreeze gel precursor solution was replaced with Li + The same concentration of Li2SO4 aqueous electrolyte was used, and all other preparation steps and parameters remained unchanged.

[0067] Comparative Example 3

[0068] The difference between this comparative example and Example 1 is that a symmetrical electrode with a fully dense structure is constructed (the core layer of the energy storage layer fiber is a dense solid structure). Specifically, in step b (3), the core layer fluid of the energy storage layer fiber is the same cross-linked keratin solution prepared in step a (3) as the heat release layer fiber. The spinning parameters are: sheath flow rate 0.8 mL / h, core layer flow rate 0.2 mL / h, and other steps and parameters remain unchanged.

[0069] Comparative Example 4

[0070] The difference between this comparative example and Example 1 is that a symmetrical electrode with a fully porous structure (the core layer of the heat-releasing layer fiber is porous) is constructed. Specifically, in step b (1), the core fluid of the heat-releasing layer fiber is the same 10wt% uncrosslinked keratin solution as the energy storage layer fiber. The spinning parameters are: sheath flow rate 0.6mL / h, core flow rate 0.2mL / h), and other steps and parameters remain unchanged.

[0071] Comparative Example 5

[0072] The difference between this comparative example and Example 1 is that the transition layer material is adjusted, using pure PI filament bundles instead of MXene coating, while other steps and parameters remain unchanged.

[0073] Test case

[0074] The electrodes obtained in the examples and comparative examples were subjected to performance tests, and the results are shown in Table 1. The specific methods are as follows:

[0075] (1) Photothermal conversion performance: A standard simulated solar light source (AM 1.5G) was used, with a radiation power density of 80 mW / cm², to vertically irradiate the electrode surface. An infrared thermal imager was used to monitor and record the highest temperature rise (ΔT) of the electrode heat-dissipating layer after reaching quasi-steady state within 10 minutes. The test environment temperature was maintained at 25±1℃ and the relative humidity at 50±5%.

[0076] (2) Electrochemical performance: The electrochemical workstation was used to test the specific capacitance in a two-electrode symmetrical system. The specific capacitance was calculated by constant current charge-discharge (GCD) curve at a current density of 1 A / g. The room temperature specific capacitance was tested at 25℃; the high light specific capacitance was tested under the same light intensity after continuous irradiation with simulated sunlight at 80mW / cm² for 10 minutes to reach thermal equilibrium.

[0077] (3) Low-temperature performance: Refer to the requirements for low-temperature environment settings in "Environmental Testing for Electrical and Electronic Products Part 2: Test Methods Test A: Low Temperature" (GB / T 2423.1-2008). Place the packaged electrode sample in a -20℃ constant temperature chamber for 2 hours to ensure uniform temperature inside and outside the sample. The test process is carried out in a pre-cooled low-temperature controlled environment (in-situ leads inside the constant temperature chamber) to ensure that the sample temperature remains constant at -20±1℃ throughout the GCD test. Calculate its retention rate of specific capacitance relative to room temperature (25℃).

[0078] (4) Cyclic stability:

[0079] 1. Charge-discharge cycle stability: The capacitance retention rate was calculated after 5000 constant current charge-discharge cycles at a current density of 5 A / g;

[0080] 2. Mechanical cycle stability: The electrode sample was subjected to 1000 cycles of repeated 180° folding tests using a bending tester (folding radius 1 mm, folding frequency 1 fold / second). The electrode surface resistance was measured before folding, and after 100, 500, and 1000 folds (using the four-probe method, test voltage 1V, and averaging of 3 different test points). The resistance change rate after 1000 folds was calculated.

[0081] Table 1

[0082]

[0083] Referring to Table 1, based on the principles of polymer solution rheology and the Stokes-Einstein theory, the photothermal heating process (ΔT = 18.5℃) in Example 1 produced a dual synergistic effect: firstly, it reduced transport resistance, as the thermal energy weakened the intermolecular hydrogen bonds within the gel network, leading to a significant decrease in electrolyte viscosity; secondly, it enhanced ion kinetic energy, causing Li... + It is easier to overcome the activation energy barrier. Therefore, Example 1 exhibits a specific capacitance of up to 330 F / g under strong light. In contrast, Comparative Example 1 (symmetric monolayer structure) has a temperature rise of only 9.8°C due to the lack of a dedicated heat-dissipating layer, and its photocapacitance gain is weak, confirming the necessity of independently constructing an efficient heat-dissipating layer.

[0084] The comparison between Example 1 and Comparative Example 2 shows that Example 1, using keratin / MXene composite fiber with PVA / LiCl antifreeze electrolyte, achieved a capacitance retention rate of 85.3% in an extremely cold environment of -20℃, and could work stably. However, Comparative Example 2, using a conventional PAN fiber and Li2SO4 aqueous solution system, suffered from freezing of the ion transport due to the freezing of the aqueous solution, resulting in a low-temperature capacitance retention rate of <10% (complete failure).

[0085] The comparison between Example 1 and Comparative Examples 3 and 4 shows that the "dense on top, porous on the bottom" asymmetric structure is key to achieving high performance. Comparative Example 3 constructed a fully dense structure, which, although exhibiting a high photothermal temperature rise (19.2°C), resulted in a sharp drop in specific capacitance to 42 F / g (only about 1 / 5 of Example 1). This confirms that without the ion transport channels constructed by the porous structure, the gel electrolyte cannot penetrate to the fiber core, rendering the internal MXene active sites unusable and essentially negating the energy storage function. Comparative Example 4 constructed a fully porous structure, which showed a photothermal temperature rise of 11.5°C and a high rate of change in resistance after bending (9.8%). This is because the lack of a dense surface layer creates a "thermal accumulation effect," allowing heat to easily dissipate through the pores. Simultaneously, the fully porous structure prevents effective locking of the gel electrolyte during vacuum encapsulation, leading to leakage and severely compromising the device's mechanical stability and cycle life.

[0086] The comparison between Example 1 and Comparative Example 5 shows that the design of the transition layer has a significant impact on the device's precision performance. In Example 1, the transition layer was coated with MXene and embedded with a temperature-sensitive micro-valve, resulting in the best synergistic effect of photothermal and energy storage. In contrast, the transition layer in Comparative Example 5 was not coated with MXene, leading to a decrease in photothermal transfer efficiency (ΔT dropped to 16.8℃) and a corresponding decrease in the high-light specific capacitance to 295 F / g. This indicates that the functionalized transition layer plays a crucial pivotal role in heat conduction and intelligent control.

[0087] In summary, the electrode prepared by this invention, through its unique asymmetric three-dimensional braided structure, successfully resolves the contradiction between "high photothermal efficiency" and "high ion transport rate" in terms of structural requirements (dense vs. porous). It also significantly outperforms existing technologies in terms of functional dynamic control, low-temperature stability, and flexibility and durability, and has broad prospects for industrialization.

[0088] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for preparing an MXene / wool keratin electrode, characterized in that, Includes the following steps: S1. Using the first cross-linked wool keratin solution as the core fluid and the first MXene dispersion as the sheath fluid, a heat-exothermic dominant fiber is prepared by coaxial spinning, and a high-density heat-exothermic layer is woven from the heat-exothermic dominant fiber. S2. A low-density transition layer is woven from polyimide filament bundles coated with MXene, and a thermally responsive micro-valve is sprayed onto the transition layer; the micro-valve is prepared by mixing poly(N-isopropylacrylamide) and multi-walled carbon nanotubes, and preparing composite gel microspheres with a diameter of 200-300 μm by reverse suspension polymerization, which serve as micro-valve. S3. Using the second wool keratin solution as the core fluid and the second MXene dispersion as the sheath fluid, a storage-dominant fiber is prepared by coaxial spinning. The storage-dominant fiber is used as the weft, and the storage-dominant fiber and carbon fiber filaments are used as the warp to weave a medium-density energy storage layer. S4. The heat-releasing layer, transition layer and energy storage layer are sequentially stacked and fixed by Z-direction binding yarn, wherein the Z-direction binding yarn is made of polyimide filament bundle to form a woven fabric. S5. Under vacuum negative pressure, polyvinyl alcohol / lithium chloride gel precursor is filled into the woven fabric, and after in-situ phase change curing, the MXene / wool keratin electrode is obtained.

2. The method for preparing the MXene / wool keratin electrode as described in claim 1, characterized in that, In S1, the concentration of the first wool keratin solution is 12-15 wt%, and it is cross-linked with genipin; the concentration of the first MXene dispersion is 8-10 mg / mL. And / or, during the coaxial spinning process, the flow rate ratio of the sheath fluid to the core fluid is (4-4.5):

1.

3. The method for preparing the MXene / wool keratin electrode as described in claim 1, characterized in that, In S3, the concentration of the second wool keratin solution is 10-12 wt%, and the concentration of the second MXene dispersion is 4-6 mg / mL; And / or, during the coaxial spinning process, the flow rate ratio of the sheath fluid to the core fluid is (2.5-3):

1.

4. The method for preparing the MXene / wool keratin electrode as described in claim 1, characterized in that, The heat-dissipating layer has a weaving density of 10-12 threads / cm and a porosity of 50-55%; the transition layer has a weaving density of 4-6 threads / cm and a porosity of 80-85%; and the energy storage layer has a weaving density of 6-8 threads / cm and a porosity of 75-80%.

5. The method for preparing the MXene / wool keratin electrode as described in claim 1, characterized in that, In S4, the tension of the Z-direction fixed yarn when it passes through and is fixed is 0.5-1.5N.

6. The method for preparing the MXene / wool keratin electrode as described in claim 1, characterized in that, In S5, the polyvinyl alcohol / lithium chloride gel precursor has a polyvinyl alcohol concentration of 10-15 wt% and a lithium chloride concentration of 2-4 mol / L; the in-situ phase change curing is completed by a freeze-thaw cycle method.

7. The method for preparing the MXene / wool keratin electrode as described in claim 1, characterized in that, Between S4 and S5, the heat-dissipating layer undergoes single-sided hot pressing and polishing treatment to form a dense barrier layer on the surface of the heat-dissipating layer.

8. An MXene / wool keratin electrode prepared by the preparation method according to any one of claims 1-7.

9. The application of the MXene / wool keratin electrode of claim 8 in a wearable electronic device.

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