A functional NiCo 2 S 4 @rGO-PU-CNTs composite fiber and its preparation method and application

Abstract

The present invention discloses a functional NiCo2S4@rGO-PU-CNTs composite fiber and its preparation method and application, belonging to the technical field of composite fiber preparation and application. The preparation of the NiCo2S4@rGO-PU-CNTs composite fiber of the present invention specifically involves in-situ self-growth of NiCo2S4 nanoparticles on the surface of GO to construct a NiCo2S4@rGO composite material. The combination of the two can increase the stability of the NiCo2S4 nanomaterial and reduce the crystal structure collapse during the cycle. At the same time, the high conductivity of graphene is utilized to enhance the electrochemical performance of the material. Moreover, the composite fiber prepared by mixing the NiCo2S4@rGO composite material, CNTs, and PU through the wet spinning technique has excellent pseudocapacitance characteristics while having high strength and flexibility, and can be widely applied to the field of intelligent wearable materials.

Description

Technical Field

[0001] The present invention relates to a functional NiCo 2 S 4 @rGO-PU-CNTs composite fiber and its preparation method and application, belonging to the technical field of composite fiber preparation and application. Background Art

[0002] The rapid development and wide application of intelligent wearable electronic devices rely on the support of safe, efficient, comfortable and wearable flexible energy storage devices. Compared with two-dimensional or three-dimensional energy storage devices, one-dimensional fiber-based energy storage devices can be easily integrated into fabrics and interlaced into arbitrary shapes due to their excellent deformability, flexibility and miniaturization potential, thus realizing the combination of energy technology and textile technology and achieving the scalable preparation of efficient energy storage systems.

[0003] NiCo 2 S 4 has the advantages of low cost, rich resources, high theoretical specific capacity, good redox reversibility, high working voltage (~1.75V), etc., and has become a very promising energy storage application material. At present, there have been studies on growing NiCo 2 S 4 on the surface of flexible conductive fibers (such as carbon fibers, stainless steel fibers, silver-plated fibers, nickel-plated fibers, etc.) through hydrothermal technology to construct fiber-based energy storage devices. However, the surface binding strength of these surface growth structures to the substrate is poor, easy to fall off, and cannot withstand repeated mechanical deformation in actual use. At the same time, it is also impossible to improve the inherent defects of NiCo 2 S 4 such as low electrical conductivity, low utilization rate, and easy collapse of crystal structure.

[0004] In addition, the prior art also mixes pseudocapacitive materials with highly conductive materials for wet spinning to quickly and continuously construct composite fiber electrodes with energy storage functions; however, ordinary blending often has defects such as low blending amount of pseudocapacitive materials (low capacity), easy aggregation and collapse of pseudocapacitive nanomaterials (low utilization rate, poor cycle performance), etc. Summary of the Invention

[0005] [Technical Problem]

[0006] In the prior art, when constructing fiber-based energy storage devices with flexible conductive fibers, there are technical problems such as poor binding strength between the energy storage material and the fiber, easy falling off, easy collapse of the crystal structure, and poor cycle performance.

[0007] [Technical Solution]

[0008] In view of the above technical problems, the present invention provides a functional composite fiber and its preparation method and application. Specifically, NiCo 2 S4 In-situ self-growth of nanoparticles constructs NiCo on the surface of GO 2 S 4 @rGO composite material, and the combination of the two can increase the stability of NiCo 2 S 4 nanomaterials, reduce the collapse of the crystal structure during cycling; at the same time, use the high conductivity of the graphene conductive network to build a "highway" to increase the electron transport efficiency of the material, improve the conductivity, accelerate the Faraday redox reaction, and enhance the electrochemical performance. At the same time, NiCo 2 S 4 @rGO composite material, CNTs, and PU are prepared into a composite fiber electrode with energy storage function by a mixed wet spinning technique. Compared with ordinary in-situ surface growth, it improves the defects of easy shedding and instability; and compared with ordinary NiCo 2 S 4 , rGO, CNTs, and PU blended spinning, it improves the capacity and electrochemical performance of the fiber electrode.

[0009] The first object of the present invention is to provide a method for preparing a functional NiCo 2 S 4 @rGO-PU-CNTs composite fiber, and the method includes the following steps:

[0010] (1) Preparation of NiCo 2 S 4 @rGO composite material

[0011] Dissolve graphene oxide (GO) in ethylene glycol (EG), and ultrasonically form a GO / EG suspension; then add nickel acetate and cobalt acetate to the suspension, magnetically stir at a constant temperature of 70-80 °C for 2-5 h, add thiourea to dissolve, and transfer to a high-pressure reaction kettle for reaction; after the reaction, naturally cool, filter, wash, and freeze-dry to obtain NiCo 2 S 4 @rGO composite material;

[0012] (2) Preparation of NiCo 2 S 4 @rGO-PU-CNTs composite fiber

[0013] Dissolve polyurethane PU, the NiCo 2 S 4 @rGO composite material prepared in step (1) and carbon nanotubes CNTs in N,N-dimethylformamide to form a spinning solution, and prepare NiCo 2 S 4 @rGO-PU-CNTs composite fiber by wet spinning.

[0014] In one embodiment, the mass-volume ratio of the graphene oxide to ethylene glycol in step (1) is 1:1 to 1.5, mg / ml.

[0015] In one embodiment, the molar ratio of nickel acetate, cobalt acetate and thiourea in step (1) is 1:2 to 3:6 to 8.

[0016] In one embodiment, the reaction conditions in step (1) are: 180 to 200 °C, and the time is 6 to 10 h.

[0017] In one embodiment, the freeze-drying conditions in step (1) are: -40 °C, <0.5 MPa, and the time is 12 - 24 h.

[0018] In one embodiment, for step (2), the mass ratio of the polyurethane, NiCo 2 S 4 @rGO composite material and carbon nanotubes is 10:(7 - 9):(1 - 3); preferably 10:7:3.

[0019] In one embodiment, for step (2), the ultrasonic stirring is carried out by ultrasonicating in an ice bath for 0.5 - 1 h, and then magnetically stirring at room temperature for 10 - 12 h.

[0020] In one embodiment, for step (2), the solid content of the spinning solution is 20 - 25%.

[0021] The second object of the present invention is to provide a NiCo 2 S 4 @rGO-PU-CNTs composite fiber prepared by the method described above.

[0022] The third object of the present invention is to provide an application of the NiCo 2 S 4 @rGO-PU-CNTs composite fiber in flexible electronic materials, flexible energy storage devices, and wearable electronic devices.

[0023] The fourth object of the present invention is to provide a method for preparing a wearable fiber-based zinc ion battery, the method comprising using the NiCo 2 S 4 @rGO-PU-CNTs composite fiber as the positive electrode, a stainless steel fiber loaded with zinc nanosheets as the negative electrode, and respectively knitting the positive electrode and the negative electrode into a fabric according to a set shape trajectory. After knitting is completed, a gel electrolyte solution is dropped onto the surface of the fabric for polymerization, thereby forming a wearable fiber-based zinc ion battery.

[0024] In one embodiment, the polymerization is carried out at 40 - 60 °C for 2 - 5 h.

[0025] In one embodiment, the preparation of the gel electrolyte solution includes: mixing an aqueous acrylic acid solution and a sodium hydroxide solution, and stirring evenly, then sequentially adding ammonium persulfate and N,N-methylenebisacrylamide, and continuously magnetically stirring at room temperature to form a gel electrolyte precursor solution; subsequently, adding a potassium hydroxide solution and a zinc acetate solution to the gel electrolyte precursor solution, and mixing evenly to obtain the gel electrolyte solution.

[0026] In one embodiment, the concentration of the potassium hydroxide solution is 6 - 10 mol / L; the concentration of the zinc acetate solution is 0.2 mol / L.

[0027] The present invention has the following beneficial effects:

[0028] (1) In the present invention, NiCo 2 S 4 nanomaterials are in-situ self-grown on the surface of GO. The combination of the two can increase the stability of NiCo 2 S 4 nanomaterials, increase the specific capacity of the fiber (230.925 mAh / g), limit the structural collapse and shedding of NiCo 2 S 4 during the charge and discharge process, and improve the cycling performance (the capacity still remains about 70% after 2000 cycles). In addition, the GO conductive network increases the electron transport efficiency of the material and accelerates the Faraday redox reaction (at a high current density of 5 A / g, the capacity can still reach 148.2 mAh / g). Compared with ordinary in-situ surface growth, the present invention improves the defects of easy shedding and instability. Compared with ordinary NiCo 2 S 4 , rGO, CNTs, and PU blending, the capacity and electrochemical performance of the fiber electrode are improved.

[0029] (2) In the present invention, CNTs and NiCo 2 S 4 @rGO are mixed and wet-spun. The carbon nanotubes can connect each graphene sheet together to form a stable double conductive network, increasing electron transport while reducing the "dead volume". The addition of PU can endow the fiber with certain stretchability to adapt to various deformations in actual use. The NiCo 2 S 4 @rGO-PU-CNTs composite fiber prepared by hydrothermal technology and wet-spinning technology has good fiber tensile strength (breaking strength: 62.38 cN / tex, breaking elongation is about 66.29%).

[0030] (3) The NiCo 2 S 4While the @rGO-PU-CNTs composite fiber has high strength and flexibility, NiCo 2 S 4 still has its inherent properties and excellent pseudocapacitive characteristics; moreover, the assembled zinc-ion battery exhibits excellent electrochemical performance, deformation resistance, and wearability, and can be effectively applied to the energy supply in the field of intelligent wearables, with wide industrial applications. Description of the Drawings

[0031] Figure 1 TEM image of the NiCo 2 S 4 @rGO composite material prepared in Example 1 of the present invention; (a) TEM image of rGO; (b) TEM image of the NiCo 2 S 4 @rGO composite material.

[0032] Figure 2 SEM images of the NiCo 2 S 4 @rGO-PU-CNTs composite fiber prepared in Example 1 of the present invention; (a) longitudinal SEM image of the NiCo 2 S 4 @rGO-PU-CNTs composite fiber; (b) cross-sectional SEM image of the NiCo 2 S 4 @rGO-PU-CNTs composite fiber; (c) detailed SEM image of the NiCo 2 S 4 @rGO-PU-CNTs composite fiber.

[0033] Figure 3 SEM images of the NiCo 2 S 4 -rGO-PU-CNTs ordinary blended composite fiber prepared in Comparative Example 3; (a) longitudinal SEM image of the ordinary blended composite fiber; (b) cross-sectional SEM image of the ordinary blended composite fiber; (c) detailed SEM image of the ordinary blended composite fiber;

[0034] Figure 4 Electrochemical performance graphs of the fiber-based zinc-ion battery prepared with the NiCo 2 S 4 @rGO-PU-CNTs composite fiber as the positive electrode and the NiCo 2 S 4 -rGO-PU-CNTs ordinary blended composite fiber prepared in Comparative Example 3 as the positive electrode; NiCo prepared in Example 1 2 S 4(a) Charge-discharge curve and (b) cycling test chart of the fiber-based zinc-ion battery with @rGO-PU-CNTs composite fiber as the positive electrode; NiCo prepared in Comparative Example 3 2 S 4 (c) Charge-discharge curve and (d) cycling test chart of the fiber-based zinc-ion battery prepared with NiCo

[0035] Figure 5 Physical picture of the woven fabric of the fiber-based zinc-ion battery prepared in Example 4 of the present invention;

[0036] Figure 6 Charge-discharge curve of the woven fabric of the fiber-based zinc-ion battery prepared in Example 4 of the present invention, and charge-discharge curves under different mechanical deformations. Detailed implementation manners

[0037] The present invention will be further described below in conjunction with embodiments, but the implementation manners of the present invention are not limited thereto.

[0038] The test methods involved in the present invention are as follows:

[0039] 1. Single fiber breaking strength

[0040] The breaking strength and breaking elongation of the fiber were tested using a YG004 type electronic single fiber strength tester; among them, the clamping distance was 20 mm, the stretching speed was 10 mm / min, the pre-tension was 0.5 cN / tex, and each cycle was stretched 10 times. After 3 cycles, the average value was taken.

[0041] 2. Resistance test

[0042] The resistance of the fiber was tested using an Agilent 34401A digital multimeter. Among them, the two test leads were touched together to zero before the test to ensure the accuracy of the measurement results; during the test, the distance between the two test leads was 1 cm, and the average value was taken after 5 tests.

[0043] 3. Electrochemical capacity

[0044] Based on the mass of the active material (NiCo in the present invention 2 S 4 @rGO) and the length of the fiber, the cycle performance test (GCD) was carried out on a Shenzhen Neware battery test system; among them, the positive electrode was NiCo 2 S 4 @rGO-PU-CNTs composite fiber or NiCo 2 S 4 -rGO-PU-CNTs ordinary blended fiber, the negative electrode was Zn@SSY fiber, and the electrolyte was: 6.0 M KOH and 0.2 M Zn(CH3 COO) 2 Mixed aqueous solution or hydrogel electrolyte (containing 6.0 M KOH and 0.2 M Zn(CH 3 COO) 2 mixed aqueous solution), with a current density of 0.5 Ag -1 , 1 Ag -1 , 1.5 Ag -1 , 2 Ag -1 , 3 Ag -1 , 4 Ag -1 , 5 Ag -1 .

[0045] 4. Cycling performance test

[0046] Based on the mass of the active material (NiCo 2 S 4 @rGO) and the length of the fiber, the cycling performance test was carried out on a Shenzhen Neware battery test system. (Performed through repeated constant current charge and discharge tests); among them, the positive electrode is NiCo 2 S 4 @rGO-PU-CNTs composite fiber or NiCo 2 S 4 -rGO-PU-CNTs ordinary blended fiber, the negative electrode is Zn@SSY fiber, and the electrolyte is: 6.0 M KOH and 0.2 M Zn(CH 3 COO) 2 mixed aqueous solution or hydrogel electrolyte (containing 6.0 M KOH and 0.2 M Zn(CH 3 COO) 2 mixed aqueous solution), with a current density of 5 Ag -1 .

[0047] Example 1

[0048] A preparation method of a functional composite fiber, the method comprising the following steps:

[0049] (1) Weigh 120 mg of graphene oxide (GO) and dissolve it in 120 mL of ethylene glycol (EG), then ultrasonicate in an ice bath for 1.5 h to form a uniform GO / EG suspension; subsequently, dissolve 3 mmol of nickel acetate and 6 mmol of cobalt acetate in the suspension, and stir magnetically at 80 °C for 2 h until a uniform suspension is formed. Then add 18 mmol of thiourea, mix and dissolve, and transfer to a high-pressure reaction kettle, react at 200 °C for 6 h; after natural cooling, filter, wash with a large amount of deionized water, and freeze-dry at -40 °C, <0.5 MPa for 12 - 24 h to obtain NiCo 2 S 4 @rGO composite material;

[0050] (2) Dissolve 1 g of polyurethane (PU), 700 mg of NiCo 2 S 4 @rGO prepared in step (1), 300 mg of carbon nanotubes (CNTs) in 10 mL of N,N-dimethylformamide (DMF). Sonicate in an ice bath for 0.5 h, then magnetically stir at room temperature for 10 - 12 h to obtain a composite spinning solution with a total mass fraction of 20%. Then inject the spinning solution into the syringe of a wet spinning device. At room temperature, adjust the wet spinning process parameters as follows: the flow rate of the spinning solution is 20 mL / h, the spinneret specification is 17G, the coagulation bath is deionized water, and the roller collection method is used to prepare composite fibers. Finally, dry the composite fibers prepared by wet spinning in a vacuum drying oven at 40°C for 2 h to remove the remaining solvent, and obtain functional NiCo 2 S 4 @rGO-PU-CNTs composite fibers.

[0051] Example 2

[0052] A method for preparing a functional composite fiber, the method comprising the following steps:

[0053] (1) Weigh 120 mg of graphene oxide (GO) and dissolve it in 120 mL of ethylene glycol (EG). Then sonicate in an ice bath for 1.5 h to form a uniform GO / EG suspension. Subsequently, dissolve 3 mmol of nickel acetate and 6 mmol of cobalt acetate in the suspension, and magnetically stir at 80°C for 2 h until a uniform suspension is formed. Then add 18 mmol of thiourea, mix and dissolve, and transfer to a high-pressure reaction kettle. React at 200°C for 6 h. After natural cooling, filter, wash with a large amount of deionized water, and freeze-dry at -40°C, <0.5 MPa for 12 - 24 h to obtain NiCo 2 S 4 @rGO composite material;

[0054] (2) Dissolve 1 g of polyurethane (PU), 800 mg of NiCo 2 S 4@rGO, 200 mg of carbon nanotubes (CNTs), were dissolved in 10 mL of N,N-dimethylformamide (DMF), and sonicated in an ice bath for 0.5 h, then magnetically stirred at room temperature for 10 - 12 h to obtain a composite spinning solution with a total mass fraction of 20%; then the spinning solution was injected into a syringe of a wet spinning device, and at room temperature, the wet spinning process parameters were adjusted as follows: the flow rate of the spinning solution was 20 mL / h, the spinneret specification was 17G, the coagulation bath was deionized water, and the roller collection method was used to prepare composite fibers; finally, the composite fibers prepared by wet spinning were dried in a vacuum drying oven at 40 °C for 2 h to remove the remaining solvent, obtaining functional NiCo 2 S 4 @rGO-PU-CNTs composite fibers.

[0055] Example 3

[0056] A preparation method of a functional composite fiber, the method comprising the following steps:

[0057] (1) Weigh 120 mg of graphene oxide (GO) and dissolve it in 120 mL of ethylene glycol (EG), then sonicate in an ice bath for 1.5 h to form a uniform GO / EG suspension; then dissolve 3 mmol of nickel acetate and 6 mmol of cobalt acetate in the suspension, and magnetically stir at 80 °C for 2 h until a uniform suspension is formed, then add 18 mmol of thiourea, after mixing and dissolving, transfer it to a high-pressure reaction kettle, and react at 200 °C for 6 h; after natural cooling, filter, wash with a large amount of deionized water, and freeze-dry at -40 °C, <0.5 MPa for 12 - 24 h to obtain NiCo 2 S 4 @rGO composite material;

[0058] (2) Dissolve 1 g of polyurethane (PU), 900 mg of NiCo 2 S 4 @rGO prepared in step (1), 100 mg of carbon nanotubes (CNTs), in 10 mL of N,N-dimethylformamide (DMF), sonicate in an ice bath for 0.5 h, then magnetically stir at room temperature for 10 - 12 h to obtain a composite spinning solution with a total mass fraction of 20%; then the spinning solution was injected into a syringe of a wet spinning device, and at room temperature, the wet spinning process parameters were adjusted as follows: the flow rate of the spinning solution was 20 mL / h, the spinneret specification was 17G, the coagulation bath was deionized water, and the roller collection method was used to prepare composite fibers; finally, the composite fibers prepared by wet spinning were dried in a vacuum drying oven at 40 °C for 2 h to remove the remaining solvent, obtaining functional NiCo 2 S 4 @rGO-PU-CNTs composite fibers.

[0059] Comparative Example 1

[0060] It is only different from Example 1 in that the carbon nanotubes in step (2) are omitted, and at the same time, the addition amount of NiCo 2 S 4 @rGO is adjusted to 1000 mg; other parameters and conditions are the same as those in Example 1.

[0061] Comparative Example 2

[0062] It is only different from Example 1 in that NiCo in step (2) is omitted 2 S 4 @rGO, and at the same time, the addition amount of carbon nanotubes is adjusted to 1000 mg; other parameters and conditions are the same as those in Example 1.

[0063] Comparative Example 3

[0064] A method for preparing a functional composite fiber, the method comprising the following steps:

[0065] (1) Weigh 3 mmol of nickel acetate and 6 mmol of cobalt acetate, dissolve them in 120 mL of ethylene glycol (EG), and ultrasonically stir in an ice bath for 1.5 h and magnetically stir at 80 °C for 2 h until a uniform suspension is formed; then add 18 mmol of thiourea, and after mixing and dissolving, transfer it to a high-pressure reaction kettle and react at 200 °C for 6 h; after natural cooling, filter, wash with a large amount of deionized water, and freeze-dry at -40 °C, <0.5 MPa for 12 - 24 h to obtain NiCo 2 S 4 nanomaterials;

[0066] (2) Dissolve 1 g of polyurethane (PU), 580 mg of NiCo 2 S 4 nanomaterials, 120 mg of reduced graphene oxide (rGO), and 300 mg of carbon nanotubes (CNTs) in 10 mL of N,N-dimethylformamide (DMF), ultrasonically stir in an ice bath for 0.5 h, and then magnetically stir at room temperature for 10 - 12 h to prepare a composite spinning solution with a total mass fraction of 20%; then inject the spinning solution into a syringe of a wet spinning device, and at room temperature, adjust the wet spinning process parameters as follows: the flow rate of the spinning solution is 20 mL / h, the spinneret specification is 17G, the coagulation bath is deionized water, and the roller collection method is used to prepare composite fibers; finally, dry the composite fibers prepared by wet spinning in a vacuum drying oven at 40 °C for 2 h to remove the remaining solvent to obtain functional NiCo 2 S 4 -rGO-PU-CNTs composite fibers.

[0067] Example 4

[0068] A method for preparing a fiber-based zinc-ion battery, the method comprising the following steps:

[0069] (1) Dissolve 7.2 mL of acrylic acid in 10 mL of deionized water and 4 g of sodium hydroxide in 5 mL of deionized water. Then, slowly mix the two in an ice bath and magnetically stir at room temperature for 0.5 h. Then, add 110 mg of ammonium persulfate and 4 mg of N,N-methylenebisacrylamide in sequence and magnetically stir at room temperature for 0.5 h to form a gel electrolyte precursor solution. Subsequently, add 5.05 g of potassium hydroxide and 0.55 g of zinc acetate to the precursor solution to obtain a gel electrolyte solution;

[0070] (2) Use the NiCo 2 S 4 @rGO-PU-CNTs composite fiber prepared in Example 1 as the positive electrode, and the stainless steel fiber loaded with zinc nanosheets as the negative electrode. Weave them into the existing threaded fabric according to the serpentine footprint respectively. Then, slowly drop the gel electrolyte solution prepared in step (1) on the fabric surface and polymerize at 60 °C for 2 h to form a fiber-based zinc-ion battery.

[0071] Example 5

[0072] The difference from Example 4 is only that in step (2), the NiCo 2 S 4 @rGO-PU-CNTs composite fiber prepared in Example 2 is used as the positive electrode, and other conditions and parameters are the same as those in Example 4 to prepare a fiber-based zinc-ion battery.

[0073] Example 6

[0074] The difference from Example 4 is only that in step (2), the NiCo 2 S 4 @rGO-PU-CNTs composite fiber prepared in Example 3 is used as the positive electrode, and other conditions and parameters are the same as those in Example 4 to prepare a fiber-based zinc-ion battery.

[0075] Comparative Example 4

[0076] The difference from Example 4 is only that in step (2), the NiCo 2 S 4 -rGO-PU-CNTs composite fiber prepared in Comparative Example 3 is used as the positive electrode, and other conditions and parameters are the same as those in Example 4 to prepare a fiber-based zinc-ion battery.

[0077] Result performance measurement

[0078] 1. Perform structural characterization on the composite fibers prepared in Example 1 and Comparative Example 3, and the results are as follows:

[0079] From Figure 2 andFigure 3 It can be seen that NiCo 2 S 4 @rGO-PU-CNTs composite fibers ( Figure 2 ) and NiCo 2 S 4 -rGO-PU-CNTs blended fibers ( Figure 3 ) both form core-shell structured fibers with a tightly packed cortex and regularly arranged pores in the core layer. This unique structure alleviates the inherent conflict between fiber strength and porosity; however, the difference is that NiCo 2 S 4 @rGO and CNTs are entangled with each other and uniformly distributed in NiCo 2 S 4 @rGO-PU-CNTs fibers, while NiCo 2 S 4 , rGO and CNTs are independent of each other and agglomerate separately in NiCo 2 S 4 -rGO-PU-CNTs fibers.

[0080] 2. The single fiber breaking strength and resistance of the composite fibers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were tested, and the test results are shown in Table 1:

[0081] Table 1. Single fiber breaking strength and resistance data

[0082]

[0083]

[0084] It can be seen from the data in Table 1 that in the absence of CNTs (Comparative Example 1), the fiber resistance is large, which is not conducive to the occurrence of electrochemical reactions; while after adding CNTs (Examples 1, 2, 3), the breaking strength of the fibers is significantly improved, and the fiber resistance is reduced; this may be because CNTs inhibit the re-stacking of rGO sheets and serve as an effective electron transfer pathway to connect graphene flakes, forming a double conductive network.

[0085] 3. The NiCo 2 S 4 @rGO-PU-CNTs composite fibers prepared in Example 1 were used as the positive electrode, and the NiCo 2 S 4 -rGO-PU-CNTs ordinary blended composite fibers prepared in Comparative Example 3 were used as the positive electrode to prepare a fiber-based zinc-ion battery for electrochemical capacity and cycle performance testing (the test electrolyte was: 6.0 mol / L KOH and 0.2 mol / L Zn(CH 3 COO) 2mixed aqueous solution), and the results are shown in Table 2 and Figure 4 as follows:

[0086] Table 2. Electrochemical capacity and cycling performance data

[0087]

[0088] As can be seen from the data in Table 2, the electrochemical capacity of the zinc-ion battery prepared from ordinary blended fibers (Comparative Example 3) is only 71.158 mAh / g, while the capacity of the zinc-ion battery prepared from the composite fibers (Example 1) of the present invention can reach 230.925 mAh / g. This may be because the ordinary blended NiCo 2 S 4 nanoparticles tend to form large-sized aggregates, resulting in a smaller contact area between the electrode and the electrolyte, a reduction in electrochemically active sites, a longer ion diffusion distance, thereby reducing the utilization rate and specific capacity. In addition, the conductivity of NiCo 2 S 4 nanoparticles themselves is poor; if only NiCo 2 S 4 and rGO are blended, the binding strength between NiCo 2 S 4 and rGO and CNTs is insufficient, and it is difficult to form a perfect conductive network, resulting in a slower electron transfer rate and poorer chemical reaction kinetics in the fiber electrode. In addition, the cycling performance of the zinc-ion battery prepared from the NiCo 2 S 4 @rGO-PU-CNTs composite fiber is significantly better than that of the NiCo 2 S 4 -rGO-PU-CNTs ordinary blended composite fiber; the reason may be that during the charge-discharge cycle of the ordinary blended fiber prepared in Comparative Example 3, the NiCo 2 S 4 nanoparticles undergo volume changes and structural collapse, and without the constraint of rGO, it is easy to form large-sized dead bodies, resulting in a rapid decline in cycling performance.

[0089] 4. Electrochemical performance tests and practical application tests were carried out on the fiber-based zinc-ion battery fabrics prepared in Example 4 and Comparative Example 4, and the results are as Figure 5 and Figure 6 shown:

[0090] From Figure 5It can be seen that the fiber-based zinc-ion battery prepared in Example 4 is woven on the fabric, which has the advantages of flexibility, stretchability, light weight, safety, scalability, easy assembly, etc., and has great potential as the preferred energy source for wearable energy textiles. In order to demonstrate the application potential of the fiber-based zinc-ion battery in the wearable field, a power wristband was constructed by connecting two fiber-based zinc-ion batteries woven on fabrics in series. The power wristband still works normally under various mechanical deformations.

[0091] From Figure 6 It can be seen that the fiber-based zinc-ion battery woven on the fabric can still maintain excellent electrochemical performance. When the current is 1 A / g, a capacity of 179.7 mAh / g can still be obtained. Moreover, under different mechanical deformations, the charge-discharge curves remain stable and there is no significant capacity loss.

Claims

1. A method for preparing functional NiCo 2 S 4 @rGO-PU-CNTs composite fibers It is characterized in that The method comprises the following steps: (1) NiCo 2 S 4 Preparation of NiCo Dissolve graphene oxide GO in ethylene glycol to form a suspension; then add nickel acetate and cobalt acetate to the suspension, magnetically stir at a constant temperature of 70-80 °C for 2-5 h, add thiourea to dissolve, and transfer to a high-pressure reactor for reaction; after the reaction, cool, filter, wash, and dry to obtain the NiCo 2 S 4 @rGO composite material; (2) NiCo 2 S 4 Preparation of @rGO-PU-CNTs Composite Fiber Dissolve polyurethane PU, the NiCo prepared in step (1) 2 S 4 @rGO composite material and carbon nanotubes CNTs in N,N-dimethylformamide to form a spinning solution, and prepare NiCo 2 S 4 @rGO-PU-CNTs composite fibers by wet spinning.

2. The method according to claim 1, It is characterized in that In step (1), the mass-volume ratio of graphene oxide to ethylene glycol is 1:1 to 1.5, mg / ml.

3. The method according to claim 1, It is characterized in that In step (1), the molar ratio of nickel acetate, cobalt acetate and thiourea is 1:2 to 3:6 to 8.

4. The method according to claim 1, It is characterized in that The reaction conditions in step (1) are: 180 - 200 °C, and the time is 6 - 10 h.

5. The method according to claim 1, It is characterized in that The polyurethane and NiCo described in step (2) 2 S 4 The mass ratio of the @rGO composite material and the carbon nanotubes is 10:(7-9):(1-3).

6. The method according to claim 1, It is characterized in that During the process of forming the spinning solution in step (2), ultrasonic stirring is also required. The ultrasonic stirring is carried out in an ice bath for 0.5 - 1 h, and then magnetically stirred at room temperature for 10 - 12 h.

7. The method according to claim 1, It is characterized in that The solid content of the spinning solution in step (2) is 20 - 25%.

8. NiCo prepared by the method according to any one of claims 1 to 7 2 S 4 @rGO-PU-CNTs composite fiber 9. NiCo as claimed in claim 8 2 S 4 Application of @rGO-PU-CNTs composite fiber in flexible electronic materials, flexible energy storage devices and wearable electronic devices.

10. A method for preparing a wearable fiber-based zinc ion battery, It is characterized in that The method includes using the NiCo 2 S 4 @rGO-PU-CNTs composite fiber as the positive electrode and the stainless steel fiber loaded with zinc nanosheets as the negative electrode, and respectively weaving the positive electrode and the negative electrode into the fabric according to a set shape trajectory. After the weaving is completed, a gel electrolyte solution is dropped on the surface of the fabric for polymerization, thereby forming a wearable fiber-based zinc ion battery.

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