A preparation method of a low-temperature core-shell coaxial fiber electrode and its products and applications

Abstract

The present invention discloses a method for preparing a low-temperature core-shell coaxial fiber electrode, its product and application, wherein a stacked two-dimensional nanosheet material is supported by a three-dimensional spherical knot structure carbon nanotube as a core electrode structure, and a continuous filamentary carbon nanotube wire film is used as a shell electrode; the carbon nanotube wire film is twisted in the same direction by a Fermat spinning method to coat the core electrode to obtain a core-shell coaxial fiber electrode. The electrode with an open core is conducive to improving the low-temperature capacity of the composite electrode, and the carbon nanotube with a high degree of orientation in the shell layer mainly serves as the mechanical support of the composite electrode. The low-temperature mechanical properties and energy storage performance of the composite electrode are optimized.

Description

Technical Field

[0001] The present invention belongs to the technical field related to low-temperature energy storage, and specifically relates to a preparation method of a low-temperature core-shell coaxial fiber electrode and its product and application. Background Art

[0002] In low-temperature environments, such as polar regions, energy supply stations, mobile power supplies, etc. usually have problems of heavy weight and large volume, which are not conducive to carrying. Flexible supercapacitors, especially fiber supercapacitors, have attracted widespread attention due to their mechanical flexibility in volume and shape, high power density, fast charge and discharge rate, long cycle life, and good suturing properties. In addition, fiber-shaped electrodes are lightweight, wearable, and easy to integrate into fabrics. They can be woven into the clothes of workers, solving the problem of difficult and inconvenient energy supply in low-temperature environments. Therefore, the application of fiber electrodes in low-temperature environments is particularly important.

[0003] Fiber electrodes need to have high carrier mobility, large available surface area, high robustness and environmental stability. However, high mechanical strength requires a high-density structure, which is not conducive to the penetration of electrolytes; high specific capacity requires a high porosity structure, and the material structure is easily destroyed during the compression process. This is a point that fiber electrodes are difficult to balance. In a low-temperature environment (for example, -20°C), on the one hand, the ionic conductivity of the electrolyte drops sharply with temperature, resulting in a loss of capacity of the supercapacitor. On the other hand, it is more difficult to maintain the flexibility of the material in a low-temperature environment. Therefore, the problem of how to balance the mechanical and capacitive properties of fiber supercapacitors at low temperatures is more prominent. Using carbon-based fibers as a substrate, pseudocapacitive materials are grown and deposited on their surface, and the prepared composite electrode materials have flexibility and increased capacity. However, pseudocapacitive materials often fall off from the substrate fibers under external mechanical deformation, and the capacity performance of the device will decay after long-term operation. In addition, pseudocapacitive materials usually agglomerate with increasing mass load, which hinders the diffusion of electrolytes, resulting in a decrease in electrochemical performance. After the pseudocapacitor material is compounded with the carbon-based material and twisted together, although it can increase the bonding strength between the pseudocapacitor material and the carbon-based material, it will make it difficult for the electrode material wrapped inside to contact the electrolyte, and the electrode material cannot be fully utilized, making it difficult to obtain high capacity.

[0004] Therefore, there is an urgent need in the art for an electrically and mechanically balanced fiber electrode material and a design method thereof. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a fiber electrode material with electrical and mechanical balance. First, carbon nanotubes and MXene materials with high conductivity, high mechanical strength and high thermal stability are selected as structural units; then, they are assembled into macroscopic bodies with high specific capacity or high mechanical strength; finally, different structural designs and assemblies are performed through the macroscopic bodies to achieve the improvement of the energy storage performance and mechanical properties of the composite fiber electrode at low temperature.

[0007] To achieve the above-mentioned purpose, the present invention provides a method for preparing a low-temperature core-shell coaxial fiber electrode: a conductive three-dimensional spherical structure material is used to support stacked conductive two-dimensional sheet materials as a core electrode structure, and a conductive flexible weavable material is used as a shell electrode; the flexible weavable material is twisted in the same direction by different spinning methods to cover the core electrode to obtain a core-shell coaxial fiber electrode.

[0008] As a preferred scheme for the preparation method of the low-temperature core-shell coaxial fiber electrode described in the present invention: the conductive two-dimensional sheet material includes one or more of graphene, M×ene, transition metal sulfide, layered metal oxide, and layered double hydroxide; the conductive three-dimensional spherical structure material can be prepared using one or more materials including carbon nanotubes, graphene, metal oxides, and metal organic frameworks, and the preparation methods include solvothermal method, carbonization, chemical vapor deposition method, template method, and ultrasonic spray pyrolysis method.

[0009] As a preferred solution of the preparation method of the low-temperature core-shell coaxial fiber electrode described in the present invention: the sizes of the conductive three-dimensional spherical structure material and the conductive two-dimensional sheet material need to be controlled at the nanometer level, and the size of the conductive three-dimensional spherical structure material is smaller than the size of the conductive two-dimensional sheet material.

[0010] As a preferred solution for the preparation method of the low-temperature core-shell coaxial fiber electrode described in the present invention: by adjusting the ratio of the conductive three-dimensional spherical structure material and the conductive two-dimensional sheet material, the pore size of the conductive two-dimensional sheet material can be adjusted to obtain the best capacity performance.

[0011] As a preferred solution of the method for preparing the low-temperature core-shell coaxial fiber electrode of the present invention: the method for preparing the core electrode material includes physical mechanical mixing and hydrothermal method.

[0012] As a preferred solution of the method for preparing the low-temperature core-shell coaxial fiber electrode described in the present invention: the conductive flexible weavable material includes carbon nanomaterials, such as carbon nanotubes, graphene, carbon nanofibers, etc., metal oxide nanowires, and metal nanowires.

[0013] As a preferred solution of the method for preparing the low-temperature core-shell coaxial fiber electrode described in the present invention: the spinning method includes dry spinning and wet spinning, and the dry spinning includes double Archimedean spinning and Fermat spinning.

[0014] As a preferred solution for the preparation method of the low-temperature core-shell coaxial fiber electrode described in the present invention: the number of coating layers and torsion density of the conductive flexible braidable material will affect the mechanical and electrical properties of the fiber electrode. By adjusting the number of coating layers and torsion density, the best electrical and mechanical properties can be obtained.

[0015] Furthermore, the torsional density of the carbon nanotube wire film is 31.40 rad cm -1 .

[0016] Furthermore, the density of the array carbon nanotubes used to prepare the carbon nanotube wire film is 55 to 65 mg cm -3 , height is 250~350μm.

[0017] Furthermore, the carbon nanotube wire film is highly oriented.

[0018] Furthermore, the oriented carbon nanotube wire film is prepared by dry spinning combined with densification treatment.

[0019] As one of the preferred schemes for the preparation method of the low-temperature core-shell coaxial fiber electrode described in the present invention, the core electrode structure is to first prepare carbon nanotubes with a three-dimensional spherical knot structure through a two-step growth method, and then drop the carbon nanotubes with a three-dimensional spherical knot structure into a two-dimensional nanosheet material dispersion, wherein, in the two-step growth method, the first step growth temperature is 750°C, and the second step growth temperature is 950°C.

[0020] As one of the preferred embodiments of the method for preparing the low-temperature core-shell coaxial fiber electrode of the present invention, the flow rate of the carbon source gas C2H2 for preparing carbon nanotubes is 100 mL min -1 The mass ratio of carbon nanotubes with three-dimensional spherical knot structures to two-dimensional nanosheet materials is 1:5.

[0021] As one of the preferred schemes of the preparation method of the low-temperature core-shell coaxial fiber electrode described in the present invention, the carbon nanotube wire film is prepared by physical vapor deposition and chemical vapor deposition to form array carbon nanotubes, which are then stripped by a blade and then dry-spun and densified.

[0022] As one of the preferred schemes of the method for preparing the low-temperature core-shell coaxial fiber electrode of the present invention, the carbon nanotube wire film is twisted in the same direction by Fermat spinning, with the number of turns being 40 to 80.

[0023] As one of the preferred embodiments of the method for preparing the low-temperature core-shell coaxial fiber electrode of the present invention, the density of the array carbon nanotubes is 55 to 65 mg cm -3 , with a height of 250 to 350 μm, and the carbon nanotube wire film is twisted in the same direction by a Fermat spinning method, with the number of turns being 60.

[0024] As one of the preferred schemes of the preparation method of the low-temperature core-shell coaxial fiber electrode described in the present invention, a three-dimensional spherical knot structured carbon nanotube is prepared by a two-step growth method, and the catalyst used is a Ni-Mn-Al-O catalyst, which is synthesized by co-precipitation and calcination reaction of Ni(NO3)3, Mn(NO3)2 and Al(NO3)3, and the calcination temperature is 700-750°C.

[0025] In general, compared with the prior art, the low-temperature core-shell coaxial fiber electrode provided by the present invention has the following beneficial effects:

[0026] 1. Carbon nanotube / Mxene core-shell coaxial fiber electrode uses knotted carbon nanotubes to support the Mxene sheets, effectively preventing the stacking of Mxene sheets. This open 3D network space increases the accessibility of ions, accelerates the transmission of ions, and provides high capacity. By adjusting the ratio of knotted carbon nanotubes and Mxene, the best capacity performance can be obtained. The oriented carbon nanotube filament film provides high mechanical strength.

[0027] 2. The breaking strength of the carbon nanotube / Mxene core-shell coaxial fiber electrode is 201MPa at room temperature and 192MPa at -60°C, both of which are higher than lace thread, indicating that it has met the mechanical property requirements of textile materials at low temperatures.

[0028] 3. The flexibility of the carbon nanotube / Mxene core-shell coaxial fiber electrode at room temperature is 3.9 (cN cm 2 ) -1 , the flexibility at -60℃ is 3.3 (cN·cm 2 ) -1 The flexibility of lace thread at room temperature is 1.8 (cN·cm 2 ) -1 This indicates that the flexibility of the carbon nanotube / Mxene core-shell coaxial fiber electrode at -60°C is not only comparable to that at room temperature, but also close to the flexibility of lace thread. Therefore, the carbon nanotube / Mxene core-shell coaxial fiber electrode is still comfortable and weavable at -60°C.

[0029] 4. When the oriented carbon nanotube wire film is coated with 60 layers, the electrical and mechanical properties of the carbon nanotube / Mxene core-shell coaxial fiber electrode reach a balance.

[0030] 5. When the ratio of carbon nanotube / Mxene core-shell coaxial fiber electrode is 1:5 and the number of carbon nanotube wire film coating layers is 60, it has the best electrochemical performance, and the capacity at room temperature is 19.1F cm -3 .

[0031] 6. Carbon nanotube / Mxene core-shell coaxial fiber electrode (1:5) supercapacitor at -60℃, 0.05A cm -3 The specific capacity at the current density is 11.36 F cm -3 , the capacity loss is only 3% after 10,000 cycles. The specific capacity of the device at room temperature is 19.1F cm -3 , compared with room temperature, the capacity retention rate is 60%.

[0032] 7. Carbon nanotube / Mxene core-shell coaxial fiber electrode (1:5) supercapacitor at 25°C with a scan rate of 20 mVs -1 The capacity is 25F g -1 , the capacity is 13F g at -60℃ -1 The capacity retention rate is 52%. The MXene-knotted CNT supercapacitor prepared from the carbon nanotube / MXene composite material obtained in steps (1) to (4) has a capacitance of 20 mV s at room temperature. -1 The capacity at a scan rate of 23 F g -1 , the capacity at -60℃ is 9F g -1 , the capacity retention rate under the same test conditions is only 39%. Therefore, compared with MXene-knotted CNT supercapacitors, the capacity retention rate of carbon nanotube / MXene core-shell coaxial fiber electrode (1:5) supercapacitors at -60°C is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0034] Figure 1 It is a schematic diagram of the preparation of carbon nanotube / Mxene core-shell coaxial structure fiber;

[0035] Figure 2 is a graph showing the relationship between the number of coating layers and the fracture strength and capacity;

[0036] Figure 3It is the cyclic voltammetry curve of carbon nanotube / Mxene core-shell coaxial structure fiber electrode with different ratios;

[0037] Figure 4 The cyclic voltammetry curves and constant current charge-discharge curves of carbon nanotube / Mxene core-shell coaxial structure fiber electrodes with different ratios;

[0038] Figure 5 is the stress-strain curve of carbon nanotube / Mxene core-shell coaxial structure fiber (1:5) at -60°C;

[0039] Figure 6 It is the volume capacity of carbon nanotube / Mxene core-shell coaxial structure fiber (1:5) at different temperatures. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] The present invention provides a low-temperature core-shell coaxial fiber electrode material. First, carbon nanotubes and MXene materials with high conductivity, high mechanical strength and high thermal stability are selected as structural units; then, they are assembled into a macroscopic body with high specific capacity or high mechanical strength; finally, different structural designs and assemblies are performed through the macroscopic body to achieve the joint improvement of energy storage performance and mechanical properties of the composite fiber electrode at low temperature. Three composite fiber electrodes are designed and prepared by changing the position of the active material. 1. MXene is deposited on the surface of the carbon nanotube fiber by a self-assembly method to achieve the improvement of the capacity of the composite fiber electrode. The carbon nanotube fiber electrode can also be treated with sulfuric acid acid to introduce functional groups to form hydrogen bonds with MXene to increase the deposition amount of MXene. However, when the loading amount is large, the active material will stack, which makes it difficult for ions to be transmitted inside. 2. After the MXene dispersion is dripped on the surface of the carbon nanotube buckypaper, unilateral curling is performed to prepare the composite fiber electrode. However, the vacuum filtration process will cause the monomers in the carbon nanotube buckypaper to have a high degree of disorder, resulting in a decrease in the conductivity of the composite fiber. 3. Through the design of the core-shell coaxial structure, the advantages of high ion accessibility of the open knot structure carbon nanotube / Mxene electrode are combined with the mechanical advantages of the oriented carbon nanotube wire film electrode, in which the electrode with an open core is conducive to improving the low-temperature specific capacity of the composite electrode, while the carbon nanotubes with a high degree of orientation in the shell mainly serve as the mechanical support of the composite electrode. The present invention found that the third type of electrode with an open core is conducive to improving the low-temperature capacity of the composite electrode, while the carbon nanotubes with a high degree of orientation in the shell mainly serve as the mechanical support of the composite electrode. The low-temperature mechanical properties and energy storage performance of the composite electrode are optimized.

[0042] See also Figure 1 The electrically and mechanically balanced fiber electrode provided by the present invention has a core-shell coaxial structure. The core knot structure carbon nanotube / Mxene has a three-dimensional open network space, which is conducive to the penetration of electrolyte, promotes the rapid diffusion of electrolyte ions in the electrode, and improves the charge storage and ion transmission at the interface between the electrode and the electrolyte. The shell structure of the carbon nanotube wire film is highly oriented. The density of the densified carbon nanotube wire film is 4.5ug cm -2 , about 3 times that of the undensified carbon nanotube film, with a diameter of 200 μm. The breaking stress at -60°C is higher than that of the lace thread. The low-temperature core-shell coaxial structure fiber electrode can be used as a working electrode in energy storage devices.

[0043] The following specific examples further illustrate the present invention in detail.

[0044] (1) The growth of knotted carbon nanotubes uses a special catalyst, Ni-Mn-Al-O catalyst, which is synthesized by coprecipitation and calcination reaction. First, Ni(NO3)3, Mn(NO3)2 and Al(NO3)3 are dissolved in 200 mL of deionized water, and the [Ni 2+ ]+[Mn 2+ ]+[Al 3+ ]=0.2mol L -1 , where n(Ni):n(Mn):n(Al)=0.4:1:2. Then, 50mL of 2.50molL -1 NaOH was added to the solution, and the mixed solution was placed in a 500 mL flask and allowed to stand at 95 ° C for 12 hours. The obtained suspension was then filtered, washed with deionized water, and then freeze-dried to obtain NiMnAl two-dimensional layered composite metal hydroxide. The NiMnAl two-dimensional layered composite metal hydroxide was then placed in a quartz boat and calcined in a quartz tube at 700 ° C for 2 hours to obtain the final product Ni-Mn-Al-O.

[0045] (2) Knot-structured carbon nanotubes were prepared by a two-step growth method. The first stage of growth was carried out in the upper region of the reactor. First, 0.20 g of Ni-Mn-Al-O nanoparticles were loaded into the reactor, and then the ambient temperature was raised to 750 °C. The nanoparticles were annealed in H2 for 10 min (H2 flow rate was 80 mL min -1 ) to form a catalyst, and then introduce carbon source gas C2H2 (C2H2 flow rate is 100mL min -1 ) for the first growth step, which lasts for 15 minutes. Then, the isolation plate is opened, and the nanoparticles with the thick-diameter carbon nanotubes and the remaining catalyst are moved to a reactor at a temperature of 950° C., and then the second growth step is carried out for 15 minutes.

[0046] (3) The tube furnace was cooled to room temperature under the protection of Ar, and the grown knot-structured carbon nanotubes were collected and heated to room temperature by HCl (5 mol L -1 ) and NaOH (13 molL -1 ) is purified to remove the residual catalyst, and the average diameter of the obtained thick diameter carbon nanotubes is about 55-70nm, and the average diameter of the thin diameter carbon nanotubes is about 15-30nm.

[0047] (4) 25 mg of the knotted carbon nanotubes prepared above were added to 50 mL of deionized water, and 50 mg of cetyltrimethylammonium bromide (CTAB) was added as a surfactant. Then, an ultrasonic cell crusher was used for 20 minutes to obtain a density of 0.50 mg mL -1 The obtained knot structure carbon nanotube dispersion was added dropwise to 1 mg mL -1 In the MXene dispersion, mCNT∶mMXene=1∶5, mCNT∶mMXene=1∶8 and mCNT∶mMXene=2∶5 were respectively controlled to prepare three kinds of mixed dispersions. After that, the obtained mixed solution was ultrasonicated in an ultrasonic cell crusher for 10 minutes, and then the knot structure carbon nanotube / MXene composite electrode was filtered onto a Celgard 3501 filter membrane by vacuum filtration. After drying in a vacuum environment at 40℃, a self-supporting knot structure carbon nanotube / MXene composite material was obtained, and then the composite electrode was cut into 0.1×0.25cm strips with a clean blade for use.

[0048] (5) High-purity, high-density, and highly oriented array carbon nanotubes were prepared by physical vapor deposition and chemical vapor deposition: First, a clean silicon wafer was plated with Al2O3 and Fe catalysts on a magnetron sputtering instrument, and then placed in a tube furnace to grow array carbon nanotubes. The growth conditions were: using a mixture of ethylene (140 sccm), Ar (590 sccm), and H2 (45 sccm), growing at 750°C for 600-1800 s, with Ar and H2 as carrier gases and ethylene as a carbon source. The average diameter of the array carbon nanotubes was about 9.25 nm, the number of walls was mostly 5, and the purity could be as high as 99.36%.

[0049] (6) Use a clean blade to cut the array carbon nanotubes (density 55-65 mg cm -3 , with a height of 250-350 μm) is peeled off from the silicon wafer substrate to form a continuous filament. Then, a clean wooden stick is used to roll up the peeled filamentous carbon nanotubes and drag them, with a length and width of 1 cm respectively; finally, by repeating the second step, the carbon nanotube silk threads of the same width and length are stacked at the same position. A carbon nanotube silk film is obtained.

[0050] (7) Densification treatment is performed on the carbon nanotube wire film prepared above: First, the carbon nanotube wire film stacked in step (6) is soaked in water and sandwiched between two clean glass slides, and then dried in a natural state for 48 hours.

[0051] (8) The mCNT:mMXene=1:5, mCNT:mMXene=1:8 and mCNT:mMXene=2:5 long composite materials prepared in step (4) are placed between two carbon nanotube wire films densified in step (7), and twisted a certain number of times in the same direction by Fermat spinning to obtain 40, 50, 60, 70 and 80 layers of carbon nanotube / MXene fiber core-shell coaxial structure fiber electrodes, respectively.

[0052] The pore size of the core structure of the low-temperature core-shell coaxial structure fiber electrode can be controlled by adjusting the ratio of the knot structure carbon nanotubes and Mxene.

[0053] The number of coating layers of the core structure of the low-temperature core-shell coaxial structure fiber electrode will affect the electrical and mechanical properties. Although the increase in the number of coating layers will improve the mechanical properties, it will increase the distance and resistance of electrolyte penetration and reduce the capacity performance. Figure 2 When the number of coating layers is 60 and mCNT∶mMXene=1∶5, the volume specific capacitance is 19.1F cm -3 , the fracture strength is 201MPa. The electrical and mechanical properties reach a balance.

[0054] In order to characterize the electrochemical performance of the energy storage device, the carbon nanotube / Mxene core-shell coaxial structure fiber electrodes with different ratios were tested, specifically:

[0055] (1) Prepare a 1 mol / L mixed organic solution of EMIMTFSI, LiTFSI, and acetonitrile as the electrolyte.

[0056] (2) Supercapacitors were constructed using carbon nanotube / Mxene core-shell coaxial structured fibers with different ratios as electrode materials.

[0057] (3) Cyclic voltammetry and constant current charge-discharge curves of carbon nanotube / Mxene core-shell coaxial fiber electrodes with different ratios were tested. The potential range was 0-1V and the scan rate was 20mV s -1 .from Figure 3 and Figure 4 It can be seen that when the ratio of carbon nanotube / Mxene core-shell coaxial structure fiber is 1:5, it exhibits the largest response current and the longest charge and discharge time because it has the optimal pore size.

[0058] The stress-strain curve of carbon nanotube / Mxene core-shell coaxial structure fiber (1:5) at -60°C and the constant current charge-discharge curve at different temperatures were tested. The current density was 0.05A cm -3 .from Figure 5It can be seen that at -60°C, the breaking strength is 192MPa, which is close to the breaking strength at room temperature. By calculating the constant current charge and discharge curves of carbon nanotube / Mxene core-shell coaxial structure fibers (1:5) at different temperatures, the volume capacity at different temperatures can be obtained, such as Figure 6 As shown. It can be seen that at -60℃, 60% of the capacity at room temperature can be maintained.

[0059] The low-temperature core-shell coaxial structure fiber electrode provided by the present invention realizes the improvement of the low-temperature specific capacity and low-temperature mechanical strength of the electrode through the open and oriented electrode structure designs. Through the design of the core-shell structure, the ion accessibility advantages of the knot structure carbon nanotube / MXene open electrode and the mechanical advantages of the oriented structure carbon nanotube wire film are combined to prepare a core-shell coaxial structure composite fiber electrode with an oriented structure carbon nanotube wire film as the shell layer and a knot structure carbon nanotube / MXene open electrode as the inner core. The high ion accessibility advantage of the open core electrode is combined with the mechanical advantages of the highly oriented electrode. The electrode with an open core is conducive to improving the capacity of the composite electrode, while the electrode with a high degree of orientation in the shell layer mainly serves as the mechanical support of the composite electrode. The optimization of the low-temperature mechanical properties and energy storage performance of the composite electrode is achieved.

[0060] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a low-temperature core-shell coaxial fiber electrode, Features: A conductive three-dimensional spherical structural material is used to support stacked conductive two-dimensional sheet materials as a core electrode structure, and a conductive flexible weavable material is used as a shell electrode; the conductive flexible weavable material is placed on the outside of the core electrode structure as an outer layer to cover the core electrode structure, and is twisted in the same direction by spinning to obtain a core-shell coaxial fiber electrode.

2. The method for preparing the low-temperature core-shell coaxial fiber electrode according to claim 1, Features: The conductive two-dimensional sheet material includes one or more of graphene, Mxene, transition metal sulfide, layered metal oxide, and layered double hydroxide; the conductive three-dimensional spherical structure material includes one or more of carbon nanotubes, graphene, metal oxide, and metal organic framework. The preparation method of the conductive three-dimensional spherical structure material includes solvent thermal method, carbonization, chemical vapor deposition method, template method or ultrasonic spray pyrolysis method.

3. The method for preparing the low-temperature core-shell coaxial fiber electrode according to claim 1 or 2, Features: The sizes of the conductive three-dimensional spherical structure material and the conductive two-dimensional sheet material need to be controlled at the nanometer level, and the size of the conductive three-dimensional spherical structure material is smaller than the size of the conductive two-dimensional sheet material.

4. The method for preparing the low-temperature core-shell coaxial fiber electrode according to claim 1, Features: The pore size of the conductive two-dimensional sheet material is 100-500 nm.

5. The method for preparing the low-temperature core-shell coaxial fiber electrode according to claim 1, Features: The conductive flexible weavable material includes one or more of carbon nanomaterials, metal oxide nanowires, and metal nanowires. The carbon nanomaterial includes one or more of carbon nanotubes, graphene, and carbon nanofibers.

6. The method for preparing the low-temperature core-shell coaxial fiber electrode according to claim 1, Features: The spinning method includes dry spinning and wet spinning, and the dry spinning includes double Archimedean spinning and Fermat spinning.

7. The method for preparing the low-temperature core-shell coaxial fiber electrode according to claim 1, Features: The number of layers of the coating is adjusted to 60, and the torsional density is 31.40 rad cm -1 .

8. The low-temperature core-shell coaxial fiber electrode prepared by the preparation method according to claim 1.

9. Use of the core-shell coaxial fiber electrode according to claim 8 in room temperature and low temperature resistant electrode materials.

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