Cobalt-doped molybdenum-tungsten sulfide, preparation method thereof, plasma treatment method and application of cobalt-doped molybdenum-tungsten sulfide

Abstract

The invention discloses a cobalt-doped molybdenum-tungsten sulfide and a preparation method and a plasma treatment method and application thereof, and relates to the technical field of electrode materials. A tungsten source, a molybdenum source, a cobalt source, a sulfur source and a complexing agent are dissolved in deionized water and then subjected to a hydrothermal reaction, and the cobalt-doped molybdenum-tungsten sulfide is obtained; and carrying out plasma treatment on the cobalt-doped molybdenum tungsten sulfide. The cobalt-doped modified molybdenum-tungsten sulfide can shorten the ion diffusion path, improve the conductivity and increase the active sites, so that the molybdenum-tungsten sulfide has more excellent conductivity; impurities on the surface of the cobalt-doped molybdenum-tungsten sulfide can be cleaned through plasma treatment, active sites are exposed, defects are formed, and therefore the electrochemical performance of the cobalt-doped molybdenum-tungsten sulfide is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrode materials, and in particular to a cobalt-doped molybdenum-tungsten sulfide, a preparation method thereof, a plasma treatment method thereof, and an application thereof. Background Art

[0002] With the rapid development of renewable energy, its intermittent and instability problems need to be solved urgently. Electrochemical energy storage technology has become an ideal solution with its advantages such as high energy density, high-efficiency conversion, and long cycle life. Supercapacitors and lithium batteries, as the two mainstays of electrochemical energy storage, each have their own characteristics. Supercapacitors are known for their rapid charging and discharging capabilities and are suitable for scenarios that require instantaneous high-power output; lithium batteries have high energy density and good cycle stability. The selection and design of electrode materials are feasible strategies to improve the energy storage and working efficiency of supercapacitors and lithium batteries. Molybdenum disulfide (MoS2) and tungsten disulfide (WS2), as two typical two-dimensional materials, have unique layered structures and have been widely studied and applied in the field of electrochemistry. However, due to the limitations of their own material structure, MoS2 and WS2 have become key bottlenecks in improving their electrochemical performance.

[0003] Molybdenum tungsten sulfide (Mo x W y S2) has shown significant advantages in the field of electrochemistry: it has high electrical conductivity, which can accelerate the electron transfer between the electrode and the electrolyte, and improve the electrochemical reaction rate and efficiency; it has a high specific capacity, which is conducive to improving the energy density of the battery; it has good electrochemical stability, and its structure and performance are stable during the cycle, which extends the service life of the electrochemical equipment; the rich oxidation states of molybdenum and tungsten enable it to participate in various redox reactions and is suitable for a variety of electrochemical devices; its band structure is adjustable and can be optimized according to different application requirements, and it has great potential in many electrochemical application scenarios such as batteries and supercapacitors.

[0004] In the field of material structure and property manipulation, impurity atom doping is a cutting-edge and highly effective strategy. Its precise controllable characteristics, highly controllable implementation path, and significant modification effects have made it a core means of optimizing material properties. In particular, doping with transition metal elements such as Fe, Co, Ni, and Cu has been shown to significantly enhance the electrochemical performance of MoS2 and WS2. From an electronic structural perspective, the doping process effectively increases the density of electronic states at the Fermi level of MoS2 or WS2, significantly improving the intrinsic conductivity of the material. Regarding the crystal structure, the introduction of dopant atoms alters the coordination environment of the surrounding atoms of MoS2 or WS2, inducing lattice mismatch and generating localized stress fields. This stress-induced effect can induce a transition from the thermodynamically stable 2H phase (hexagonal) to the metallic 1T phase (tetragonal), where it exhibits unique electron delocalization and abundant active sites, significantly enhancing the material's electrocatalytic activity and energy storage performance.

[0005] Plasma is widely used as a way to regulate the structure and phase of materials due to its non-contact, highly controllable, and multifunctional characteristics. Plasma treatment is a technology that uses plasma to physically and chemically treat the surface of a material. Under the action of plasma, processes such as cleaning, oxidation modification, and thin film deposition can occur on the surface of the material. Plasma activates gas molecules to produce active substances such as ions, free radicals, and excited molecules. These active substances can react with the surface of the material to achieve surface cleaning, remove organic matter, and enhance surface adhesion, providing an important means to enhance material performance and functionality.

[0006] The present invention aims to improve the Mo x W y Electrochemical performance of S2. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a preparation method of plasma cobalt-doped molybdenum tungsten sulfide. On the one hand, the electronic structure and crystal defects of molybdenum tungsten sulfide can be regulated by doping with impurity atoms, thereby introducing more active sites, optimizing its electrical conductivity and redox reaction activity, and thus improving the specific capacity; on the other hand, the surface of molybdenum tungsten sulfide is modified by plasma treatment to improve the interface contact between molybdenum tungsten sulfide and electrolyte, enhance the wettability of molybdenum tungsten sulfide, and reduce the charge transfer resistance, thereby effectively improving the electrochemical performance and providing strong support for the development of high-performance electrochemical devices.

[0008] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions: The first object of the present invention is to provide a method for preparing cobalt-doped molybdenum-tungsten sulfide, wherein a tungsten source, a molybdenum source, a cobalt source, a sulfur source and a complexing agent are dissolved in deionized water and then subjected to a hydrothermal reaction to obtain cobalt-doped molybdenum-tungsten sulfide.

[0009] The second object of the present invention is to provide a cobalt-doped molybdenum-tungsten sulfide obtained by the above-mentioned preparation method.

[0010] The third object of the present invention is to provide a plasma treatment method for the cobalt-doped molybdenum tungsten sulfide.

[0011] A fourth object of the present invention is to provide applications of the cobalt-doped molybdenum tungsten sulfide and the cobalt-doped molybdenum tungsten sulfide treated by the plasma treatment method in lithium-ion batteries and supercapacitors.

[0012] A fifth object of the present invention is to provide a lithium-ion battery using the cobalt-doped molybdenum-tungsten sulfide or the cobalt-doped molybdenum-tungsten sulfide treated by the plasma treatment method as a negative electrode material.

[0013] A sixth object of the present invention is to provide a supercapacitor using the cobalt-doped molybdenum tungsten sulfide or the cobalt-doped molybdenum tungsten sulfide treated by the plasma treatment method as a negative electrode material.

[0014] The beneficial effects of the present invention are: (1) The method for preparing cobalt-doped molybdenum tungsten sulfide provided by the present invention has the characteristics of cheap and readily available raw materials, low energy consumption, and simple process. It can realize the large-scale preparation of cobalt-doped molybdenum tungsten sulfide, which is conducive to scientific research promotion and industrialization.

[0015] (2) The present invention can shorten the ion diffusion path, improve the conductivity, increase the active sites, and make the molybdenum tungsten sulfide have more superior conductivity by cobalt doping modification of molybdenum tungsten sulfide.

[0016] (3) The present invention can clean the surface impurities of cobalt-doped molybdenum tungsten sulfide through plasma treatment, expose active sites, form defects, and thus improve the electrochemical properties of cobalt-doped molybdenum tungsten sulfide. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 X-ray diffraction (XRD) patterns of the cobalt-doped molybdenum tungsten sulfide after plasma treatment in Examples 1 to 5 and the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1; Figure 2 1 is a scanning electron microscope (SEM) image of the cobalt-doped molybdenum tungsten sulfide after plasma treatment in Examples 1 to 5 and the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1; Figure 3The SEM images, transmission electron microscope (TEM) images and energy dispersive spectrum (EDS) images of the cobalt-doped molybdenum tungsten sulfide after plasma treatment in Example 3 and the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1 are shown; wherein, (a-c) are TEM images of the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1; (d) is an SEM image of the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1; (e-g) are TEM images of the cobalt-doped molybdenum tungsten sulfide after plasma treatment in Example 3; (h) is an SEM image of the cobalt-doped molybdenum tungsten sulfide after plasma treatment in Example 3; and (im) is an EDS image of (h); Figure 4 Cyclic voltammetry (CV) curves, constant current charge-discharge (GCD) curves, rate performance curves, and electrochemical impedance spectroscopy (EIS) curves of three electrodes assembled using the plasma-treated cobalt-doped molybdenum tungsten sulfide of Examples 1 to 5 and the non-plasma-treated cobalt-doped molybdenum tungsten sulfide of Comparative Example 1 as negative electrode materials, respectively; (a) is a CV curve; (b) is a GCD curve; (c) is a rate performance curve; and (d) is an EIS. Figure 5 CV curves and GCD curves of three electrodes assembled using the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1 and the molybdenum tungsten sulfide not doped with cobalt and not plasma treated in Comparative Example 2 as negative electrode materials; (a) is the CV curve; (b) is the GCD curve; Figure 6 Rate performance curves of lithium-ion batteries assembled using the plasma-treated cobalt-doped molybdenum tungsten sulfide of Examples 1 to 5 and the plasma-untreated cobalt-doped molybdenum tungsten sulfide of Comparative Example 1 as negative electrode materials; Figure 7 Graphs showing the cycle performance of lithium-ion batteries assembled using the plasma-treated cobalt-doped molybdenum tungsten sulfide of Examples 1 to 5 and the plasma-untreated cobalt-doped molybdenum tungsten sulfide of Comparative Example 1 as negative electrode materials. DETAILED DESCRIPTION

[0018] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below with reference to specific embodiments and illustrations.

[0019] The present invention provides a method for preparing cobalt-doped molybdenum-tungsten sulfide. A tungsten source, a molybdenum source, a cobalt source, a sulfur source and a complexing agent are dissolved in deionized water and then subjected to a hydrothermal reaction to obtain the cobalt-doped molybdenum-tungsten sulfide.

[0020] Furthermore, the tungsten source is ammonium paratungstate.

[0021] Furthermore, the molybdenum source is ammonium molybdate, sodium molybdate and hydrates thereof.

[0022] Furthermore, the cobalt source is cobalt nitrate and its hydrate.

[0023] Furthermore, the sulfur source is at least one of thiourea, thioacetamide, and cysteine.

[0024] Furthermore, the complexing agent is oxalic acid.

[0025] Furthermore, the mass proportions of the tungsten source, molybdenum source, cobalt source, sulfur source and complexing agent are 18-23%, 9-10%, 0.3-3%, 51-53% and 14-16% respectively, with the total mass proportion being 100%.

[0026] Furthermore, the temperature of the hydrothermal reaction is 180-220° C., and the time is 24-48 hours.

[0027] The present invention provides a cobalt-doped molybdenum-tungsten sulfide obtained by the above-mentioned preparation method.

[0028] Furthermore, the molecular formula of the cobalt-doped molybdenum tungsten sulfide is Mo 0.64 W 0.36 S2.

[0029] Furthermore, the cobalt doping amount in the cobalt-doped molybdenum tungsten sulfide is 0.3-0.5%.

[0030] The present invention also provides a plasma treatment method for the cobalt-doped molybdenum tungsten sulfide.

[0031] Furthermore, the plasma treatment is carried out at room temperature and pressure, with a power of 0-50W and a treatment time of 5-10min.

[0032] Furthermore, the gas used in the plasma treatment is air. The advantages of using air are extremely low cost, easy access, good environmental protection, no secondary pollution, and suitability for large-scale industrial production.

[0033] The present invention also provides the use of the cobalt-doped molybdenum tungsten sulfide and the cobalt-doped molybdenum tungsten sulfide treated by the plasma treatment method in lithium-ion batteries and supercapacitors.

[0034] The present invention also provides a lithium-ion battery, using the cobalt-doped molybdenum-tungsten sulfide or the cobalt-doped molybdenum-tungsten sulfide treated by the plasma treatment method as a negative electrode material.

[0035] The present invention also provides a supercapacitor, which uses the cobalt-doped molybdenum tungsten sulfide or the cobalt-doped molybdenum tungsten sulfide treated by the plasma treatment method as a negative electrode material.

[0036] Example 1 (1) Ammonium paratungstate (0.6240 g, 0.19 mmol), thiourea (1.4209 g, 18.67 mmol), ammonium molybdate tetrahydrate (0.2897 g, 0.23 mmol), oxalic acid (0.4256 g, 4.73 mmol) and cobalt nitrate hexahydrate (0.0114 g, 0.04 mmol) were stirred and dissolved in 20 mL of deionized water. The mixture was then transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene. The autoclave was then placed in a 220°C oven for hydrothermal reaction for 24 h. After the reaction, the oven was naturally cooled to room temperature. The reaction solution was removed and centrifuged three times with 25 mL of deionized water and twice with 25 mL of 95% ethanol at a centrifuge speed of 8000 rpm for 3 min each time. The resulting solid was vacuum dried at 60°C for 24 h to obtain cobalt-doped molybdenum tungsten sulfide.

[0037] (2) The cobalt-doped molybdenum tungsten sulfide prepared in step (1) is placed in a quartz transparent glass container with a hole on the top, and then the container is placed in a plasma generator, and plasma treated for 5 minutes at room temperature and pressure with a power of 10 W to obtain cobalt-doped molybdenum tungsten sulfide after plasma treatment.

[0038] Examples 2 to 5 The method of Example 1 is followed, except that the plasma processing power is adjusted to 20, 30, 40, and 50 W, respectively.

[0039] Comparative Example 1 The method of Example 1 is followed, except that the cobalt-doped molybdenum tungsten sulfide is not subjected to plasma treatment.

[0040] The inductively coupled plasma spectrum of the cobalt-doped molybdenum tungsten sulfide sample prepared in Comparative Example 1 was tested. The sample mass was 0.0546 g and the constant volume was 25 mL. The test results are shown in Table 1.

[0041] Table 1

[0042] From the element contents in Table 1, it can be determined that the molecular formula of molybdenum tungsten sulfide is Mo 0.64 W 0.36 S2.

[0043] Comparative Example 2 The method of Example 1 is followed, except that the molybdenum tungsten sulfide is not doped with cobalt and is not plasma treated.

[0044] Figure 1The XRD patterns of the cobalt-doped molybdenum tungsten sulfide after plasma treatment in Examples 1 to 5 and the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1 are shown. Figure 1 From the XRD diagram, it can be seen that the characteristic diffraction peaks at 14.0°, 32.7° and 57.0° correspond to the (002), (100) and (110) crystal planes, respectively. After plasma treatment, the (002) peak becomes stronger, indicating that the crystallinity of the sample is improved, which will lead to an increase in the ion / electron transmission efficiency, improve the sample interface stability, and enhance the reaction reversibility.

[0045] Figure 2 The SEM images of the cobalt-doped molybdenum tungsten sulfide after plasma treatment in Examples 1 to 5 and the cobalt-doped molybdenum tungsten sulfide without plasma treatment in Comparative Example 1 are shown. Figure 2 It can be seen that after plasma treatment, cobalt-doped molybdenum tungsten sulfide presents a nano-flower ball with a layered structure, providing more active sites for electrochemical reactions.

[0046] Figure 3 TEM and EDS images of the cobalt-doped molybdenum-tungsten sulfide after plasma treatment in Example 1. Figure 3 It can be seen that cobalt-doped molybdenum tungsten sulfide was successfully prepared and the cobalt element was evenly distributed. At the same time, the microscopic morphology of the cobalt-doped molybdenum tungsten sulfide after plasma treatment was a nanoflower ball formed by stacking nanosheets.

[0047] The following steps are used to assemble the supercapacitor: (1) Cut the nickel foam into 1 cm × 2 cm size and weigh it, which is recorded as m1.

[0048] (2) 80 mg of the plasma-treated cobalt-doped molybdenum tungsten sulfide of Examples 1 to 5 or the plasma-untreated cobalt-doped molybdenum tungsten sulfide of Comparative Example 1, 10 mg of superconducting carbon powder (SuperP), and 10 mg of polyvinylidene fluoride (PVDF) powder were placed in a mortar, and an appropriate amount of N-methylpyrrolidone (NMP) was added dropwise. The mixture was thoroughly ground to obtain a uniform slurry.

[0049] (3) The slurry was evenly coated on the nickel foam with a coating area of ​​1 cm × 1 cm, and dried in a vacuum drying oven at 60 ° C for 12 h to obtain an electrode sheet, which was weighed and recorded as m 2。

[0050] (4) The electrochemical performance of the assembled three electrodes was tested using an electrode sheet with m2-m1=1~2 mg as the working electrode, a platinum electrode as the counter electrode, an Ag / AgCl electrode as the reference electrode, and a sodium sulfate solution (1 mol / L) as the electrolyte.

[0051] Figure 4The CV curves, GCD curves, rate performance curves and EIS curves of three electrodes assembled using the cobalt-doped molybdenum tungsten sulfide after plasma treatment in Examples 1 to 5 and the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1 as negative electrode materials. Figure 4 It can be seen that the three-electrode assembled with cobalt-doped molybdenum tungsten sulfide as the negative electrode material after 30W plasma treatment has the longest discharge time. According to the formula C=It / mV, the specific capacitance can be calculated. Therefore, the three-electrode assembled with cobalt-doped molybdenum tungsten sulfide as the negative electrode material after 30W plasma treatment has the highest specific capacitance, and its specific capacitance at various current densities is significantly better than that of cobalt-doped molybdenum tungsten sulfide at other plasma treatment powers. In addition, the plasma-treated cobalt-doped molybdenum tungsten sulfide is significantly better than the untreated cobalt-doped molybdenum tungsten sulfide, which proves that plasma treatment helps improve the electrochemical performance of cobalt-doped molybdenum tungsten sulfide.

[0052] Figure 5 CV curves and GCD curves of three electrodes assembled using the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1 and the molybdenum tungsten sulfide not subjected to cobalt doping and plasma treatment in Comparative Example 2 as negative electrode materials. Figure 5 It can be seen that the CV curve of the cobalt-doped molybdenum tungsten sulfide has a larger area, and the GCD curve also has a longer discharge time, that is, it has a larger specific capacitance, which shows that cobalt doping improves the electrochemical performance of the molybdenum tungsten sulfide.

[0053] The following steps are used to assemble the lithium-ion battery: (1) Dissolve 0.4 g of PVDF powder in 20 mL of NMP to obtain a PVDF solution.

[0054] (2) Take 35 mg of the cobalt-doped molybdenum tungsten sulfide after plasma treatment in Examples 1 to 5 or the cobalt-doped molybdenum tungsten sulfide not subjected to plasma treatment in Comparative Example 1, 10 mg of SuperP and 250 μL of the PVDF solution prepared in step (1), add an appropriate amount of NMP dropwise, and stir thoroughly to obtain a uniform slurry.

[0055] (3) Wipe the copper foil with alcohol to remove the surface oxide layer, and cut it into discs with a diameter of 1.2 cm. Weigh it and record it as m1.

[0056] (4) The slurry prepared in step (2) is evenly coated on the rough surface of the copper foil with a coating thickness of 100 μm. After coating, it is dried in an oven at 60°C for 1 hour. The copper foil loaded with the active material is compacted using a tablet press to obtain an electrode sheet, which is weighed and recorded as m2.

[0057] (5) The battery was assembled in an argon environment glove box (oxygen content ≤ 0.01 ppm, water content ≤ 0.01 ppm), with the negative electrode shell as the bottom layer, the electrode sheet prepared in step (2) was placed in the center of the negative electrode shell, 2 to 3 drops of electrolyte (LiPF6, EC:EMC:DMC=1:1:1v%) were added, and the PP diaphragm was covered. 1 to 2 drops of electrolyte were added, lithium sheets were added, gaskets and springs were pressed on, and finally the positive electrode shell was covered. The battery was packaged using a punching machine with a punching pressure of 5 MPa and a punching time of 10 s. The button cell was taken out of the glove box and the residual electrolyte on the surface was wiped to obtain a lithium-ion battery.

[0058] (6) The lithium-ion battery obtained in step (5) was allowed to stand for 8 hours and subjected to performance testing using a blue battery testing system. Different currents were set at different current densities to test the rate performance and cycle performance of the lithium-ion battery.

[0059] The current is calculated as follows: I=0.7·ρ 电流 m 1000 Where m=m2-m1.

[0060] Figure 6 The rate performance curves of lithium-ion batteries assembled using the plasma-treated cobalt-doped molybdenum tungsten sulfide of Examples 1 to 5 and the plasma-untreated cobalt-doped molybdenum tungsten sulfide of Comparative Example 1 as negative electrode materials. Figure 6 It can be seen that at a current density of 5C, the lithium-ion battery assembled with cobalt-doped molybdenum tungsten sulfide treated with 30W plasma as the negative electrode material has the largest specific capacity, which shows that plasma treatment can improve the electrochemical properties of cobalt-doped molybdenum tungsten sulfide.

[0061] Figure 7 The graphs are for the cycle performance of lithium-ion batteries assembled using the plasma-treated cobalt-doped molybdenum tungsten sulfide of Examples 1 to 5 and the plasma-untreated cobalt-doped molybdenum tungsten sulfide of Comparative Example 1 as negative electrode materials. Figure 7 It can be seen that the lithium-ion battery assembled with cobalt-doped molybdenum tungsten sulfide treated with 30W plasma as the negative electrode material has the best cycle performance, and its specific capacity is still the highest after 600 cycles.

[0062] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing cobalt-doped molybdenum-tungsten sulfide, characterized by: A tungsten source, a molybdenum source, a cobalt source, a sulfur source and a complexing agent are dissolved in deionized water and then subjected to a hydrothermal reaction to obtain cobalt-doped molybdenum-tungsten sulfide.

2. The preparation method according to claim 1, wherein: The tungsten source is ammonium paratungstate; The molybdenum source is ammonium molybdate, sodium molybdate and hydrates thereof; The cobalt source is cobalt nitrate and its hydrate; The sulfur source is at least one of thiourea, thioacetamide, and cysteine; The complexing agent is oxalic acid; The mass proportions of the tungsten source, molybdenum source, cobalt source, sulfur source and complexing agent are 18-23%, 9-10%, 0.3-3%, 51-53% and 14-16% respectively, with the total mass proportion being 100%.

3. The preparation method according to claim 1, wherein: The temperature of the hydrothermal reaction is 180-220° C., and the time is 24-48 hours.

4. Cobalt-doped molybdenum tungsten sulfide obtained by the preparation method according to any one of claims 1 to 3.

5. The cobalt-doped molybdenum-tungsten sulfide according to claim 4, characterized in that: The molecular formula of the cobalt-doped molybdenum tungsten sulfide is Mo 0.64 W 0.36 S2; The cobalt doping amount in the cobalt-doped molybdenum tungsten sulfide is 0.3-0.5%.

6. A plasma treatment method for cobalt-doped molybdenum tungsten sulfide according to claim 4 or 5.

7. The plasma processing method according to claim 6, wherein: The plasma treatment is carried out at room temperature and pressure, with a power of 0-50W and a treatment time of 5-10min; The gas used for plasma treatment is air.

8. Use of the cobalt-doped molybdenum tungsten sulfide according to any one of claims 4 to 5 and the cobalt-doped molybdenum tungsten sulfide treated by the plasma treatment method according to any one of claims 6 to 7 in lithium-ion batteries and supercapacitors.

9. A lithium-ion battery, characterized in that: The cobalt-doped molybdenum tungsten sulfide according to any one of claims 4 to 5 or the cobalt-doped molybdenum tungsten sulfide treated by the plasma treatment method according to any one of claims 6 to 7 is used as the negative electrode material.

10. A supercapacitor, characterized in that: The cobalt-doped molybdenum tungsten sulfide according to any one of claims 4 to 5 or the cobalt-doped molybdenum tungsten sulfide treated by the plasma treatment method according to any one of claims 6 to 7 is used as the negative electrode material.

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