Preparation method of cobalt-doped graphene / molybdenum disulfide composite fiber electrode

Abstract

The invention discloses a preparation method of a cobalt-doped graphene / molybdenum disulfide composite fiber electrode, and relates to a preparation method of a composite fiber electrode material. The invention aims to solve the problem of performance degradation of molybdenum disulfide / carbon composite fibers caused by irreversible reaction of molybdenum sulfide and decomposition into metal molybdenum clusters and sulfur components when the existing fibrous molybdenum sulfide / carbon composite electrode is used for the sodium ion battery. The method comprises the following steps: 1, synthesizing an ultrathin MoS2 nanosheet; and 2, preparing the Co-doped MoS2 / graphene oxide fiber by wet spinning. The method is used for preparing the cobalt-doped graphene / molybdenum disulfide composite fiber electrode.

Description

Technical Field

[0001] This invention relates to a method for preparing composite fiber electrode materials. Background Technology

[0002] Fiber electrode materials are key components for the performance of wearable fiber batteries. Common synthesis strategies for attaching active materials to fiber electrodes mainly involve three methods: dip-coating, in-situ synthesis, and co-spinning. The dip-coating method suffers from low adhesion between the fiber's curved surface and the active material. In-situ synthesis produces fiber electrodes with low active material loading, limiting their practical application. Co-spinning involves manufacturing aligned sheet-like fiber structures through large-scale industrial wet spinning, directly assembling the active material and graphene, thus avoiding the aforementioned drawbacks. However, very few materials are suitable for co-spinning, limiting the application of this synthesis strategy. Precursor materials meeting the requirements of co-spinning must be in the form of ultrathin nanosheets or nanoribbons and should not undergo irreversible transformation reactions during ion insertion / extraction. In most cases, these irreversible transformation reactions directly damage the composite fiber structure, impairing its mechanical and electrical properties, and may even lead to the decomposition of the composite fiber structure, thereby reducing its mechanical and electrical properties. Ultrathin two-dimensional layered materials that are easy to peel, prepare, or synthesize are suitable precursors for aligned sheet-like fibers. However, many readily cospun two-dimensional materials undergo irreversible transformation reactions during their initial cycles, including sulfides, selenides, and phosphides. Catalysis can convert irreversibly transformed two-dimensional materials into reversibly transformed ones, broadening the range of available cospun precursors. Expanding the scope of composite fiber material systems is crucial for researchers to select and develop fiber electrodes suitable for various applications.

[0003] Molybdenum disulfide is the main component of molybdenite, and is an abundant and inexpensive graphene-like layered metal sulfide. It has a relatively large theoretical sodium storage capacity of 670 mAh g⁻¹. -1 However, the low conductivity, easy pulverization during cycling, and easy dissolution of molybdenum and sulfur components severely limit the electrochemical sodium storage performance of MoS2-based anode materials. Furthermore, the weak van der Waals interactions between the layers can promote the exfoliation of two-dimensional layered materials, serving as precursors for fibrous batteries. However, MoS2 can react with Na and irreversibly transform into Mo and Na2S at low potentials. This irreversible reaction means the disappearance of the MoS2 layered structure, directly leading to a sharp decline in the mechanical properties and reduced conductivity of the fibrous electrode. In addition, reaction intermediates (such as Na2S) generated by the conversion reaction may cause the intermediates to dissolve, further exacerbating capacity decay. Summary of the Invention

[0004] This invention aims to address the problem that when existing fibrous molybdenum disulfide / carbon composite electrodes are used in sodium-ion batteries, molybdenum disulfide undergoes an irreversible reaction and decomposes into metallic molybdenum atom clusters and sulfur components, leading to a degradation in the performance of the molybdenum disulfide / carbon composite fibers. Therefore, this invention provides a method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode.

[0005] A method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode, comprising the following steps:

[0006] I. Synthesis of Ultrathin MoS2 Nanosheets:

[0007] MoS2 powder and lithium pyrene were added to 1,2-dimethoxyethane and stirred. The supernatant was then removed by centrifugation and vacuum drying to obtain a precipitate. Deionized water was added to the precipitate and ultrasonically exfoliated. Finally, centrifugation was used to remove residual coarse particles to obtain a purified suspension of ultrathin MoS2 nanosheets.

[0008] II. Preparation of Co-doped MoS2 / graphene oxide fibers by wet spinning:

[0009] The ultrathin MoS2 nanosheet purification suspension, cobalt acetate solution, and graphene oxide aqueous solution were mixed, heated, stirred, and concentrated to obtain a spinning solution. The spinning solution was loaded into an injection pump and wet spun. Finally, the solution was chemically reduced with hydroiodic acid and treated at high temperature to obtain a cobalt-doped graphene / molybdenum disulfide composite fiber electrode.

[0010] The beneficial effects of this invention are:

[0011] This invention synthesizes a self-supporting, oriented cobalt-doped MoS2 / graphene composite fiber (CoMGCF) suitable for fibrous sodium-ion batteries, specifically a sandwich material of monolayer molybdenum disulfide and carbon. A stable MoS2 suspension was successfully obtained by exfoliating the bulk MoS2 material through a lithium pyrene intercalation reaction. The composite fiber was prepared using a wet spinning process, in which ultrathin MoS2 nanosheets and graphene are interleaved and stacked, constructing an oriented layer-to-layer structure within the composite fiber. Experiments show that the fiber electrode with unique cobalt-doped active sites achieves a reversible reaction from Mo / Na2S to MoS2 during charging, rather than the irreversible reaction from Mo / Na2S to Mo / S as is common in traditional methods. Thanks to the cobalt-doped catalyst, the fiber electrode can maintain its interlayered stacked structure, effectively preventing the aggregation of Mo metal clusters and the dissolution of sulfides during repeated charge-discharge cycles. Attached Figure Description

[0012] Figure 1SEM images, EDS spectra, Raman spectra, XPS spectra, XRD spectra, mechanical stretching curves, and optical images of CoMGCF prepared in Example 1 and MGCF prepared in the comparative experiment. (a) is an SEM image of CoMGCF, and the inset is a flexible optical image of CoMGCF. (b) is a surface SEM image of CoMGCF. (c) is a SEM image of the cross-section of CoMGCF. (d) to (i) are SEM images of CoMGCF and their corresponding EDS spectra. (j) is a TEM image of graphene exfoliated from CoMGCF and its corresponding EDS spectra. (k) is the Raman spectrum of CoMGCF and MGCF. (l) is the Co 2p XPS spectrum of CoMGCF and MGCF. (m) is the XRD spectrum of CoMGCF and MGCF. (n) is the mechanical stretching curve of CoMGCF and MGCF. The inset is an optical image of CoMGCF with a 50g weight suspended in it. (o) is an optical image of CoMGCF that can be spun and an optical image of CoMGCF embedded in a fabric.

[0013] Figure 2 The constant current charge-discharge curves, cycle performance, and rate performance of the CoMGCF prepared in Example 1 and the MGCF prepared in the comparative experiment are shown in (a). -1 The constant current charge-discharge curves at 0.1 A g are shown in (b) for CoMGCF and MGCF. -1 The cycling performance of CoMGCF is shown in (c) as the constant current discharge / charge curves of CoMGCF at different rates, (d) as the rate performance of CoMGCF and MGCF, and (e) as the rate performance of CoMGCF and MGCF at 2.0A g. -1 Long-cycle performance under these conditions;

[0014] Figure 3 In-situ Raman spectra of CoMGCF prepared in Example 1 and MGCF prepared in the comparative experiment during the first cycle: (a) In-situ Raman spectrum of CoMGCF during the first cycle; (b) In-situ Raman spectrum of MGCF during the first cycle. Detailed Implementation

[0015] Specific Implementation Method 1: This implementation method describes a method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode, which is carried out according to the following steps:

[0016] I. Synthesis of Ultrathin MoS2 Nanosheets:

[0017] MoS2 powder and lithium pyrene were added to 1,2-dimethoxyethane and stirred. The supernatant was then removed by centrifugation and vacuum drying to obtain a precipitate. Deionized water was added to the precipitate and ultrasonically exfoliated. Finally, centrifugation was used to remove residual coarse particles to obtain a purified suspension of ultrathin MoS2 nanosheets.

[0018] II. Preparation of Co-doped MoS2 / graphene oxide fibers by wet spinning:

[0019] The ultrathin MoS2 nanosheet purification suspension, cobalt acetate solution, and graphene oxide aqueous solution were mixed, heated, stirred, and concentrated to obtain a spinning solution. The spinning solution was loaded into an injection pump and wet spun. Finally, the solution was chemically reduced with hydroiodic acid and treated at high temperature to obtain a cobalt-doped graphene / molybdenum disulfide composite fiber electrode.

[0020] The catalytic effect of heteroatom doping can effectively induce a reversible reaction in MoS2, making it possible to apply graphene / molybdenum disulfide composites to fiber-shaped sodium-ion batteries. In irreversible reactions, nanoscale molybdenum clusters can aggregate into larger particles during long cycles. This aggregation disrupts the overlapping ultrathin MoS2 nanosheets and GO fiber structure, significantly reducing the mechanical properties and conductivity of the fiber electrode. Furthermore, the aggregation of Mo atoms means that many sulfur molecules cannot contact the Mo clusters and dissolve in the electrolyte, thus reducing the S content. The catalytic effect of Co doping can transform the irreversible reaction into a reversible one. First, the reversible transformation of MoS2 helps to maintain the structure of MoS2 nanosheets within the fiber, which is fundamental to maintaining the excellent mechanical properties, conductivity, and flexibility of the fiber electrode. Second, the recrystallization and redistribution of molybdenum clusters can maintain them in a uniformly distributed nanodot state. This helps to prevent the aggregation of Mo clusters and the dissolution of sulfur in the electrolyte. Finally, the MoS2 sheets in Na + Fracture occurs during the insertion / extraction process, which provides Na + The storage provides more active sites and promotes charge transfer, thereby enhancing electrochemical reaction kinetics with excellent rate capability. This method successfully prepared electrode materials that can be applied to wearable batteries, expanding the application scope of two-dimensional materials in the field of wearable energy.

[0021] The beneficial effects of this embodiment are:

[0022] This embodiment synthesizes a self-supporting, oriented cobalt-doped MoS2 / graphene composite fiber (CoMGCF) suitable for fibrous sodium-ion batteries, specifically a sandwich material of monolayer molybdenum disulfide and carbon. A stable MoS2 suspension was successfully obtained by exfoliating the bulk MoS2 material through a lithium pyrene intercalation reaction. The composite fiber was prepared using a wet spinning process, in which ultrathin MoS2 nanosheets and graphene were interleaved and stacked, constructing an oriented layer-to-layer structure within the composite fiber. Experiments show that the fiber electrode with unique cobalt-doped active sites achieves a reversible reaction from Mo / Na2S to MoS2 during charging, rather than the irreversible reaction from Mo / Na2S to Mo / S as is common in traditional methods. Thanks to the cobalt-doped catalyst, the fiber electrode can maintain its interlayered stacked structure, effectively preventing the aggregation of Mo metal clusters and the dissolution of sulfides during repeated charge-discharge cycles.

[0023] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the molar ratio of MoS2 powder to lithium pyrene in step one is 1 g:(0.2~0.8) mmol; the volume ratio of MoS2 powder to 1,2-dimethoxyethane in step one is 1 g:(20~150) mL. Everything else is the same as in Specific Implementation Method One.

[0024] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the stirring described in step one is specifically carried out at a stirring speed of 60 r / min to 180 r / min for 6 h to 12 h; the centrifugation to remove residual coarse particles described in step one is specifically carried out at a rotation speed of 5000 r / min to 8000 r / min for 15 min to 30 min. Everything else is the same as in Specific Implementation Method One or Two.

[0025] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the ultrasonic stripping described in step one is specifically performed under a power of 700W~2000W for 15min~35min; the mass ratio of the precipitate to the volume of deionized water in step one is 1g:(50~100)mL. Everything else is the same as in Specific Implementation Methods One to Three.

[0026] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in the following ways: the concentration of the ultrathin MoS2 nanosheet purification suspension in step two is 0.1 mg / mL to 2 mg / mL; the concentration of the cobalt acetate solution in step two is 2 mg / mL to 5 mg / mL; the concentration of the graphene oxide aqueous solution in step two is 20 mg / mL to 25 mg / mL; the volume ratio of the ultrathin MoS2 nanosheet purification suspension to the cobalt acetate solution in step two is 1:(0.1~5); the volume ratio of the ultrathin MoS2 nanosheet purification suspension to the graphene oxide aqueous solution in step two is 1:(1~10). Everything else is the same as in Specific Implementation Methods One to Four.

[0027] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the heating and stirring described in step two is specifically carried out at a temperature of 35℃~80℃ and a stirring speed of 60r / min~180r / min for 6h~12h. Everything else is the same as in Specific Implementation Methods One to Five.

[0028] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the concentration mentioned in step two specifically refers to concentrating the ultrathin MoS2 nanosheets and graphene oxide in the spinning solution to a total concentration of 20 mg / mL to 25 mg / mL. Everything else is the same as in Specific Implementation Methods One to Six.

[0029] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: in step two, wet spinning is performed at a feed rate of 0.01 mL / min to 1 mL / min, and the rotating coagulation bath used in the wet spinning process is a 2 wt% to 37 wt% calcium chloride ethanol solution. Everything else is the same as in Specific Implementation Methods One to Seven.

[0030] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the chemical reduction of hydroiodic acid in step two is specifically carried out by immersion in 5% to 20% hydroiodic acid at a temperature of 25°C to 50°C for 5 to 10 hours. Everything else is the same as in Specific Implementation Methods One to Eight.

[0031] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the high-temperature treatment described in step two is specifically vacuum drying at a temperature of 570℃ to 820℃ for 12 to 24 hours. Everything else is the same as in Specific Implementation Methods One to Nine.

[0032] The beneficial effects of the present invention are verified using the following embodiments:

[0033] Example 1:

[0034] A method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode, comprising the following steps:

[0035] I. Synthesis of Ultrathin MoS2 Nanosheets:

[0036] MoS2 powder and lithium pyrene were added to 1,2-dimethoxyethane and stirred for 10 h at a stirring speed of 120 r / min. The supernatant was then removed by centrifugation and vacuum dried to obtain a precipitate. Deionized water was added to the precipitate and the mixture was sonicated for 20 min at a power of 800 W. Finally, the mixture was centrifuged for 25 min at a speed of 5500 r / min to remove residual coarse particles, resulting in a purified suspension of ultrathin MoS2 nanosheets.

[0037] The molar ratio of MoS2 powder to lithium pyrene is 1 g: 0.5 mmol; the mass ratio of MoS2 powder to 1,2-dimethoxyethane is 1 g: 50 mL; and the mass ratio of the precipitate to deionized water is 1 g: 75 mL.

[0038] II. Preparation of Co-doped MoS2 / graphene oxide fibers by wet spinning:

[0039] A purified suspension of ultrathin MoS2 nanosheets, a cobalt acetate solution, and an aqueous solution of graphene oxide were mixed and then heated and stirred for 12 hours at 80°C and a stirring speed of 120 r / min. The mixture was concentrated until the total concentration of ultrathin MoS2 nanosheets and graphene oxide in the spinning solution was 20 mg / mL. The spinning solution was then loaded into a syringe pump and wet-spun at a feed rate of 0.1 mL / min. The rotating coagulation bath used in the wet spinning process was an 8 wt% calcium chloride ethanol solution. The fibers were then chemically reduced in 10% hydroiodic acid at 80°C for 6 hours. Finally, the fibers were vacuum-dried at 660°C for 20 hours to obtain a cobalt-doped graphene / molybdenum disulfide composite fiber electrode (CoMGCF).

[0040] The concentration of the ultrathin MoS2 nanosheet purification suspension is 2.0 mg / mL; the concentration of the cobalt acetate solution is 2 mg / mL; the concentration of the graphene oxide aqueous solution is 20 mg / mL; the volume ratio of the ultrathin MoS2 nanosheet purification suspension to the cobalt acetate solution is 1:1; and the volume ratio of the ultrathin MoS2 nanosheet purification suspension to the graphene oxide aqueous solution is 1:5.

[0041] Comparative Experiment: This comparative experiment differs from Example 1 in that: the cobalt acetate solution is omitted in step two; the volume ratio of the purified suspension of ultrathin MoS2 nanosheets to the aqueous solution of graphene oxide is 1:1; and the composite fiber electrode obtained in step two is abbreviated as MGCF. Everything else is the same as in Example 1.

[0042] Figure 1 The images show SEM images, EDS spectra, Raman spectra, XPS spectra, XRD spectra, mechanical stretching curves, and optical images of CoMGCF prepared in Example 1 and MGCF prepared in the comparative experiment. (a) is an SEM image of CoMGCF, with an inset showing a flexible optical image of CoMGCF. (b) is a surface SEM image of CoMGCF. (c) is a SEM image of the cross-section of CoMGCF. (d) to (i) are SEM images of CoMGCF and their corresponding EDS spectra. (j) is a TEM image of graphene exfoliated from CoMGCF and its corresponding EDS spectra. (k) is the Raman spectrum of CoMGCF and MGCF. (l) is the Co 2p XPS spectrum of CoMGCF and MGCF. (m) is the XRD pattern of CoMGCF and MGCF. (n) is the mechanical stretching curve of CoMGCF and MGCF, with an inset showing an optical image of CoMGCF with a 50g weight suspended from it. (o) is an optical image of CoMGCF that can be spun and an optical image of CoMGCF embedded in a fabric. As shown in the figure, the material prepared by this process has a fibrous morphology with a fiber diameter of approximately 700 μm. The fiber is composed of stacked graphene and MoS2 sheets. CoMGCF fibers are composed of C, O, Mo, S, and Co elements. The graphene sheets peeled off the fiber surface are composed of C, O, and Co elements, indicating that Co element has been successfully doped into the fiber. Raman spectra of CoMGCF and MGCF show the presence of 2H-MoS2 in the fiber; Co2p XPS spectra of CoMGCF and MGCF indicate that Co is divalent; XRD patterns of CoMGCF and MGCF show the presence of hexagonal 2H-MoS2 phase in the fiber; CoMGCF and MGCF have good mechanical properties, can hang 50g hair, and the fibers are spinnable.

[0043] Figure 2 The constant current charge-discharge curves, cycle performance, and rate performance of the CoMGCF prepared in Example 1 and the MGCF prepared in the comparative experiment are shown in (a). -1 The constant current charge-discharge curves at 0.1 A g are shown in (b) for CoMGCF and MGCF. -1 The cycling performance of CoMGCF is shown in (c) as the constant current discharge / charge curves of CoMGCF at different rates, (d) as the rate performance of CoMGCF and MGCF, and (e) as the rate performance of CoMGCF and MGCF at 2.0A g. -1The long-cycle performance is shown in Figures (a) and (b). During the first cycle, the discharge and charge specific capacities of CoMGCF were 608.6 mAh g, respectively. -1 and 469.1mAh g -1 The initial coulombic efficiency (ICE) was 77.1%. The irreversible initial capacity loss during the first cycle can be attributed to irreversible reactions and the formation of a solid electrolyte interphase (SEI) layer. In contrast, the discharge and charge specific capacities of MGCF were 597.6 mAh g⁻¹. -1 and 459.0mAh g -1 The initial coulombic efficiency was 76.8%. After 200 cycles, the CoMGCF electrode still maintained a 439.0 mAh g⁻¹. -1 The high reversible capacity of the MGCF is significantly superior to that of the MGCF. In contrast, the MGCF exhibits rapid capacity decay and poor cycling stability, which may be due to its irreversible conversion reaction. Furthermore, the reversible capacity of the MGCF rapidly decays to 101.5 mAh g⁻¹ after only 100 cycles. -1 When the current density is increased to 0.1 A g -1 0.2A g -1 0.5A g -1 0.8A g -1 1.0A g -1 and 2.0A g -1 At that time, the corresponding reversible capacity was 446.2 mAh g. -1 383.0mAh g -1 356.2mAh g -1 310.7mAh g -1 262.5mAh g -1 and 188.7mAhg -1 When the current density returns to 0.1 A g -1 At that time, the discharge specific capacity recovered to 366.8 mAh g. -1 This indicates that CoMGCF has a stable structure. In Figure (e), 2.0A g is also shown. -1 The cycling performance was investigated to evaluate the stability of CoMGCF. The fiber electrode was first activated at a low current for 30 cycles, followed by cycling at 2.0 A g. -1 Performance was tested. CoMGCF at 2.0 Ag -1 The reversible capacity of 224.1 mAh g remains stable after 1000 cycles. -1 The average coulombic efficiency is close to 100%, significantly better than MGCF. In stark contrast, MGCF exhibits poor cycling stability, with its capacity rapidly decaying to 54.3 mAh g⁻¹ after 50 cycles.-1 .

[0044] Figure 3 In-situ Raman spectra of CoMGCF prepared in Example 1 and MGCF prepared in the comparative experiment were obtained during the first cycle. (a) In-situ Raman spectrum of CoMGCF during the first cycle, (b) In-situ Raman spectrum of MGCF during the first cycle. As shown in the figure, the Raman spectra of both CoMGCF and MGCF at open-circuit voltage exhibit the typical fingerprint characteristics of 2H-MoS2. When the voltage drops to 0.8V, the intensity of the two characteristic peaks of 2H-MoS2 decreases, while the characteristic peak of 1T-MoS2 appears and gradually intensifies. When the deep discharge reaches 0.46V, the characteristic peaks of 2H-MoS2 and 1T-MoS2 disappear, which is attributed to their structural decomposition. This may indicate that a phase transition from 2H to 1T has occurred, accompanied by the transformation of MoS2 to the Mo metallic state and Na2S. During charging, CoMGCF and MGCF exhibit completely different behaviors. Cobalt-doped MoS2 (CoMGCF) reproduces the fingerprint characteristic peak of 1T-MoS2 at 1.80V, indicating a reversible structural transition. However, even when the potential was increased to 3.0V, the characteristic fingerprint peaks of 1T-MoS2 or 2H-MoS2 in pure MoS2 (MGCF) did not appear. Furthermore, no characteristic fingerprint peak intensity of 1T-MoS2 or 2H-MoS2 was detected in MGCF under complete desulfurization, indicating that its structure had undergone irreversible reactions. In contrast, the structure of CoMGCF exhibits reversible structural evolution during discharge / charge due to the catalytic effect of cobalt doping.

Claims

1. A method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode, characterized in that... It is done in the following steps: I. Synthesis of Ultrathin MoS2 Nanosheets: MoS2 powder and lithium pyrene were added to 1,2-dimethoxyethane and stirred. The supernatant was then removed by centrifugation and vacuum drying to obtain a precipitate. Deionized water was added to the precipitate and ultrasonically exfoliated. Finally, centrifugation was used to remove residual coarse particles to obtain a purified suspension of ultrathin MoS2 nanosheets. II. Preparation of Co-doped MoS2 / graphene oxide fibers by wet spinning: The ultrathin MoS2 nanosheet purification suspension, cobalt acetate solution, and graphene oxide aqueous solution were mixed, heated, stirred, and concentrated to obtain a spinning solution. The spinning solution was loaded into an injection pump and wet spun. Finally, the solution was chemically reduced with hydroiodic acid and treated at high temperature to obtain a cobalt-doped graphene / molybdenum disulfide composite fiber electrode.

2. The method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode according to claim 1, characterized in that... The molar ratio of MoS2 powder to lithium pyrene in step one is 1 g:(0.2~0.8) mmol; the molar ratio of MoS2 powder to 1,2-dimethoxyethane in step one is 1 g:(20~150) mL.

3. The method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode according to claim 1, characterized in that... The stirring described in step one is specifically carried out at a stirring speed of 60 r / min to 180 r / min for 6 h to 12 h; the centrifugation to remove residual coarse particles described in step one is specifically carried out at a speed of 5000 r / min to 8000 r / min for 15 min to 30 min.

4. The method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode according to claim 1, characterized in that... The ultrasonic stripping described in step one is specifically performed under a power of 700W~2000W for 15min~35min; the mass ratio of the precipitate to the volume of deionized water in step one is 1g:(50~100)mL.

5. The method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode according to claim 1, characterized in that... The concentration of the ultrathin MoS2 nanosheet purification suspension in step two is 0.1 mg / mL to 2 mg / mL; the concentration of the cobalt acetate solution in step two is 2 mg / mL to 5 mg / mL; the concentration of the graphene oxide aqueous solution in step two is 20 mg / mL to 25 mg / mL; the volume ratio of the ultrathin MoS2 nanosheet purification suspension to the cobalt acetate solution in step two is 1:(0.1~5); the volume ratio of the ultrathin MoS2 nanosheet purification suspension to the graphene oxide aqueous solution in step two is 1:(1~10).

6. The method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode according to claim 1, characterized in that... The heating and stirring described in step two specifically involves heating and stirring for 6 to 12 hours at a temperature of 35℃ to 80℃ and a stirring speed of 60 r / min to 180 r / min.

7. The method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode according to claim 1, characterized in that... The concentration mentioned in step two specifically refers to concentrating the total concentration of ultrathin MoS2 nanosheets and graphene oxide in the spinning solution to 20 mg / mL to 25 mg / mL.

8. The method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode according to claim 1, characterized in that... In step two, wet spinning is performed at a feed rate of 0.01 mL / min to 1 mL / min, and the rotating coagulation bath used in the wet spinning process is a 2 wt% to 37 wt% calcium chloride ethanol solution.

9. The method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode according to claim 1, characterized in that... The chemical reduction of hydroiodic acid mentioned in step two specifically involves immersing the sample in hydroiodic acid with a mass percentage of 5% to 20% for 5 to 10 hours at a temperature of 25°C to 50°C.

10. The method for preparing a cobalt-doped graphene / molybdenum disulfide composite fiber electrode according to claim 1, characterized in that... The high-temperature treatment mentioned in step two specifically involves vacuum drying at a temperature of 570℃~820℃ for 12h~24h.

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