MoS2 self-supporting electrode, its preparation method, and its application in electrochemical energy storage.

Abstract

The application discloses a MoS2 self-supporting electrode and a preparation method and application thereof in electrochemical energy storage, relates to the technical field of nano functional materials and electrochemical energy storage, and organically combines the morphology regulation of P123, the surface and interface engineering of plasma and the integrated construction of the self-supporting electrode, so as to synergistically solve the bottlenecks of MoS2 in conductivity, active site utilization and interface transmission, fully release the energy storage potential of MoS2 in electrochemistry, and has important research significance and application value.

Description

Technical Field

[0001] This invention relates to the fields of nanomaterials and electrochemical energy storage technology, specifically to a MoS2 self-supporting electrode, its preparation method, and its application in electrochemical energy storage. Background Technology

[0002] Molybdenum disulfide (MoS2), a typical two-dimensional layered transition metal sulfide, has attracted widespread attention in the field of electrochemical energy storage due to its unique graphene-like layered structure, high theoretical specific capacity, and tunable electronic properties. However, its practical application still faces multiple challenges. First, the intrinsic electronic conductivity of MoS2 needs further improvement to support faster charge transport. Second, MoS2 nanosheets are prone to stacking and agglomeration during synthesis and assembly, leading to a significant reduction in effective specific surface area and burying a large number of active sites, thus severely limiting its energy storage performance. Finally, traditional electrode fabrication processes typically require the introduction of insulating polymer binders to fix the active material, which increases the interfacial resistance inside the electrode, hinders ion diffusion, and restricts the improvement of the overall electrode performance. To overcome these challenges, researchers have conducted extensive explorations at both the material synthesis and electrode engineering levels.

[0003] At the material synthesis level, morphology and structure control are crucial. Among these, the nonionic triblock copolymer P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide, EO...) is a key example. 20 -PO 70 -EO 20 This structure exhibits a unique structure-directing effect. The hydrophilic PEO and hydrophobic PPO segments of P123 can self-assemble into micelle templates in a hydrothermal environment. These micelles effectively adsorb metal precursor ions (such as MoO4²⁻) and guide the epitaxial growth of MoS2 around them through spatial confinement, thereby constructing a multi-level nanoflower-like morphology with an open structure. This structure possesses a high specific surface area and abundant mesopores, providing not only three-dimensional channels for rapid wetting and transport of electrolyte ions but also exposing more active sites at the edges, which is beneficial for improving the intrinsic electrochemical activity of the material.

[0004] At the electrode fabrication level, developing self-supporting electrodes is an effective way to overcome the inherent defects of traditional powder coating processes. By directly growing active materials in situ on flexible conductive substrates such as carbon cloth, the use of insulating binders can be completely avoided, achieving close electrical contact between the active material and the current collector, and establishing a stable and low-resistance electron transport path. Simultaneously, the firm anchoring of the active material on the substrate helps buffer volume changes during charge and discharge processes, thereby significantly improving the structural integrity and cycle stability of the electrode. However, how to directly grow MoS2 on carbon cloth with both ideal microstructure and surface properties remains a topic requiring further research. Summary of the Invention

[0005] To address the bottlenecks faced by intrinsic MoS2 materials, such as poor conductivity, a small number of active sites, and unstable electrode structures, this invention provides a method for preparing an integrated self-supporting electrode. The core of this method lies in using P123 to precisely control the growth morphology of MoS2 at the molecular scale, combining plasma treatment to deeply optimize the phase structure and surface chemistry of the material, and relying on carbon cloth to achieve binder-free integrated integration of the electrode, ultimately obtaining a high-performance energy storage electrode.

[0006] The technical problem to be solved by this invention is achieved by the following technical solution:

[0007] The first objective of this invention is to provide a method for preparing a MoS2 self-supporting electrode, comprising the following steps:

[0008] (1) Dissolve the molybdenum source, sulfur source and surfactant P123 in deionized water to obtain a precursor solution;

[0009] (2) Carbon cloth was placed in a precursor solution and subjected to a hydrothermal reaction to obtain carbon cloth loaded with MoS2.

[0010] (3) Plasma treatment was performed on the carbon cloth loaded with MoS2 to obtain a MoS2 self-supporting electrode.

[0011] Furthermore, the molybdenum source is ammonium molybdate and its hydrate.

[0012] Furthermore, the sulfur source is thioacetamide.

[0013] Furthermore, the mass ratio of the molybdenum source, sulfur source and P123 is (0.8~1): (0.2~0.4): (0.8~1).

[0014] P123, through its self-assembly behavior, acts as a soft template to precisely guide the directional growth of MoS2 on the surface of carbon fiber, forming a nanoflower-like structure with high specific surface area and hierarchical pores.

[0015] Furthermore, the hydrothermal reaction is carried out at a temperature of 170-190°C for 16-20 hours.

[0016] Furthermore, the plasma treatment is carried out under normal temperature and pressure conditions, with a power of 40~60 W, a gas flow rate of 70~90 sccm, and a treatment time of 3~8 min.

[0017] Furthermore, the gas used for plasma treatment is air. The advantages of using air are low cost, easy availability, environmental friendliness, no secondary pollution, and suitability for large-scale industrial production.

[0018] To further optimize the surface state and electrode interface properties of the material, this invention subjected MoS2-loaded carbon cloth to plasma treatment. Plasma, rich in highly reactive particles, can clean the material surface, regulate surface energy, and introduce controllable defects through physical and chemical interactions, thereby optimizing the electrode / electrolyte interface and enhancing charge transfer kinetics. Notably, the multi-level MoS2 nanostructures synthesized under P123 guidance, due to their high specific surface area and open pores, provide a larger area and depth for plasma treatment, extending the surface modification effect from the outer surface to the internal structure of the material, achieving a more comprehensive performance improvement.

[0019] A second objective of this invention is to provide a MoS2 self-supporting electrode obtained by the aforementioned preparation method. MoS2 is grown in situ on the surface of carbon cloth fibers in a three-dimensional nanoflower-like structure, which possesses a high specific surface area and abundant porosity.

[0020] A third objective of this invention is to provide the application of the self-supporting MoS2 electrode in electrochemical energy storage.

[0021] A fourth objective of this invention is to provide a lithium-ion battery that uses the MoS2 self-supporting electrode as the negative electrode.

[0022] The fifth object of the present invention is to provide a supercapacitor using the MoS2 self-supporting electrode as the negative electrode.

[0023] The beneficial effects of this invention are:

[0024] 1. The multi-functional synergistic effect of P123:

[0025] Precise morphology control: P123 serves as a soft template to guide the formation of a three-dimensional multi-level nanoflower structure MoS2, which greatly increases the specific surface area and the number of active sites of the electrode.

[0026] Inhibiting particle aggregation: The steric hindrance effect of P123 effectively prevents the disordered stacking of MoS2 nanosheets and maintains open porous channels.

[0027] Surface modification: The introduction of P123 alters the chemical microenvironment of the MoS2 surface, providing a more favorable interface for its subsequent plasma treatment.

[0028] 2. Advantages of the integrated electrode structure: The active material is grown directly on the carbon cloth in situ, forming a binder-free, self-supporting integrated electrode. This structure ensures extremely low interfacial resistance and excellent mechanical stability, significantly improving the electrode's rate performance and cycle life.

[0029] 3. Deep optimization of plasma treatment: Plasma treatment not only cleans the material surface, but may also achieve synergistic enhancement of the material's "bulk phase" and "interface" properties through interaction with the special nanostructure generated by P123 modification.

[0030] 4. Simple, green and efficient process: The entire process is simple, plasma treatment is fast and uses air, which is environmentally friendly and low-cost, and has good prospects for large-scale application. Attached Figure Description

[0031] Figure 1 X-ray diffraction analysis patterns of PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3;

[0032] Figure 2 Scanning electron microscope images of PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3;

[0033] Figure 3 The energy dispersive spectroscopy (EDS) spectrum of the PT-MoS2-P123 sample prepared in Example 1 is shown below.

[0034] Figure 4 Using PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3 as working electrodes, Ag / AgCl as reference electrodes, and platinum sheets as counter electrodes, 1 mol·L -1 Cyclic voltammetry (a), constant current charge-discharge curve (b), rate performance curve (c), and electrochemical impedance spectroscopy (d) of a three-electrode system assembled with Na2SO4 aqueous solution as electrolyte.

[0035] Figure 5 Using the PT-MoS2-P123 sample prepared in Example 1 as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode, 1 mol·L -1 Cyclic stability test results of a three-electrode system assembled with Na2SO4 aqueous solution as electrolyte;

[0036] Figure 6 The rate performance curves of lithium-ion batteries assembled using PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3, respectively, as negative electrodes are shown. Detailed Implementation

[0037] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments and illustrations.

[0038] Example 1

[0039] (1) Dissolve 0.9 g ammonium molybdate tetrahydrate, 0.3 g thioacetamide and 0.9 g surfactant P123 in 30 mL of deionized water to obtain a precursor solution.

[0040] (2) The dried carbon cloth (1 cm × 2 cm) was immersed in the above precursor solution, and then transferred to a 50 mL polytetrafluoroethylene-lined high-pressure reactor. The reactor was then sealed and placed in an oven at 180 °C for 18 h. After the reaction was completed, the carbon cloth was allowed to cool naturally to room temperature. The carbon cloth was then removed and ultrasonically washed three times with deionized water and anhydrous ethanol, respectively. Finally, it was dried in a vacuum drying oven at 60 °C for 12 h to obtain carbon cloth loaded with MoS2.

[0041] (3) The carbon loaded with MoS2 was placed in the sample chamber of the plasma processing equipment and the sample was subjected to plasma processing under normal temperature and pressure conditions. Air was introduced as the working gas, the gas flow rate was set to 80 sccm, the processing power was 50 W, and the processing time was 5 min to obtain the MoS2 self-supporting electrode (abbreviated as PT-MoS2-P123).

[0042] Example 2

[0043] The method is the same as in Example 1, except that the plasma processing power in step (3) is adjusted to 40W, the processing time is adjusted to 8 min, and the gas flow rate is adjusted to 100 sccm.

[0044] Example 3

[0045] The method is the same as in Example 1, except that the plasma processing power in step (3) is adjusted to 60W, the processing time is adjusted to 3 min, and the gas flow rate is adjusted to 50 sccm.

[0046] Example 4

[0047] The method is the same as in Example 1, except that the reaction temperature in step (2) is adjusted to 170°C and the reaction time is adjusted to 20 h.

[0048] Example 5

[0049] The method is the same as in Example 1, except that the reaction temperature in step (2) is adjusted to 190°C and the reaction time is adjusted to 16 h.

[0050] Example 6

[0051] The method of Example 1 is followed, except that the amount of feed in step (1) is adjusted to 0.8 g ammonium molybdate tetrahydrate, 0.2 g thioacetamide and 0.8 g surfactant P123.

[0052] Example 7

[0053] The method of Example 1 is followed, except that the amount of feed in step (1) is adjusted to 1 g ammonium molybdate tetrahydrate, 0.4 g thioacetamide and 1 g surfactant P123.

[0054] Comparative Example 1

[0055] The method of Example 1 was followed, except that the plasma treatment in step (3) was not performed, and the MoS2 / carbon cloth electrode (referred to as MoS2-P123) synthesized with P123 assistance was obtained.

[0056] Comparative Example 2

[0057] The method of Example 1 is followed, except that surfactant P123 is not added in step (1) to obtain a plasma-treated MoS2 / carbon cloth electrode (PT-MoS2 for short).

[0058] Comparative Example 3

[0059] The method of Example 1 is different in that the surfactant P123 is not added in step (1) and the plasma treatment in step (3) is not performed to obtain the MoS2 / carbon cloth electrode (abbreviated as MoS2).

[0060] Figure 1 X-ray diffraction patterns of PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3 are shown. Figure 1 It can be seen that the diffraction peaks appearing near 14.4°, 33.5° and 58.3° correspond to the (002), (100) and (110) crystal planes of MoS2, respectively, confirming the successful synthesis of MoS2.

[0061] Figure 2 Scanning electron microscope (SEM) images of the PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3. Figure 2 It can be seen that the surface of carbon fiber is uniformly covered with three-dimensional nanoflower-like MoS2 assembled from ultrathin nanosheets. Its open and porous morphology is conducive to electrolyte wetting and provides a rich active surface.

[0062] Figure 3This is an energy dispersive spectroscopy (EDS) surface scan analysis of the PT-MoS2-P123 sample prepared in Example 1. Figure 3 It can be seen that the Mo (brown) and S (red) elements are uniformly overlapped in the nanoflower region, confirming that MoS2 grows uniformly on the carbon cloth.

[0063] The PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3 were cut into 1 cm × 1 cm sizes and used as working electrodes. A platinum sheet electrode was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. 1 mol·L -1 A Na₂SO₄ aqueous solution was used as the electrolyte to assemble a three-electrode system. Cyclic voltammetry curves of the three-electrode system were then performed using an electrochemical workstation (scan rate 20 mV·s). -1 ), constant current charge-discharge curve (current density 1 mA·cm) -2 Rate performance curves (current density 1~20 mA·cm) -2 Electrochemical impedance spectroscopy and cyclic stability tests were performed, and the results are shown in […]. Figure 4 and Figure 5 .

[0064] Figure 4 Using PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3 as working electrodes, Ag / AgCl as reference electrodes, and platinum sheets as counter electrodes, 1 mol·L -1 Cyclic voltammetry (a), galvanostatic charge-discharge curve (b), rate performance curve (c), and electrochemical impedance spectroscopy (d) of a three-electrode system assembled using Na2SO4 aqueous solution as the electrolyte. Figure 4 (a) It can be seen that the CV curve closure area of ​​the PT-MoS2-P123 electrode is the largest, indicating that it has the highest specific capacitance; the CV areas of the MoS2-P123 and PT-MoS2 electrodes are next, but both are significantly larger than those of the MoS2 electrode. This shows that the introduction of P123 and plasma treatment can effectively improve the storage capacity of the electrodes, and the two together exhibit the best synergistic effect. Figure 4 (b) It can be seen that the PT-MoS2-P123 electrode exhibits the longest discharge time, and its specific capacitance is the highest according to the formula C=IΔt / mV. The discharge times of the MoS2-P123 and PT-MoS2 electrodes are in the middle and significantly longer than those of the MoS2 electrode. All GCD curves show an approximately symmetrical triangular shape, indicating that the electrodes have good charge-discharge reversibility. Figure 4 (c) It can be seen that the PT-MoS2-P123 electrode exhibits the highest specific capacity at all current densities, and at 20 mA·cm⁻¹-2 Maintaining high capacity even at high current densities indicates excellent rate performance and rapid ion diffusion kinetics. The rate performance of MoS2-P123 and PT-MoS2 electrodes is superior to that of the MoS2 electrode, but inferior to that of the PT-MoS2-P123 electrode, further confirming the importance of the synergistic effect of morphology regulation and surface modification. The diameter of the semicircle in the high-frequency region of the electrochemical impedance spectroscopy corresponds to the charge transfer resistance (Rct), which is determined by… Figure 4 (d) It can be seen that the PT-MoS2-P123 electrode has the smallest semicircular diameter, indicating that it has the lowest Rct and the optimal interfacial charge transport kinetics. The Rct of the MoS2-P123 and PT-MoS2 electrodes is lower than that of the MoS2 electrode, but higher than that of the PT-MoS2-P123 electrode. In the low-frequency region, the slope of the curve of the PT-MoS2-P123 electrode is closest to vertical, indicating that it has the most ideal capacitive behavior and the fastest ion diffusion rate.

[0065] Figure 5 Using the PT-MoS2-P123 sample prepared in Example 1 as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode, 1 mol·L -1 Cyclic stability test results of a three-electrode system assembled using Na2SO4 aqueous solution as the electrolyte. Figure 5 It can be seen that at 20 mA·cm -2 After 10,000 cycles at a current density, the capacity retention rate is as high as 92.1%, and the coulombic efficiency remains above 99%, proving that the electrode has excellent cycle stability.

[0066] The carbon cloth used to prepare the electrodes in this invention was cut into circular pieces with a diameter of 12 mm, weighed, and the mass was recorded as m1. The PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3 were cut into circular pieces with a diameter of 12 mm and used as negative electrode sheets, weighed, and the mass was recorded as m2. Battery assembly was carried out in a glove box under argon atmosphere (oxygen content ≤0.01 ppm, water content ≤0.01 ppm). With the negative electrode shell as the bottom layer, the negative electrode sheet was placed in the center of the negative electrode shell, and 3 drops of electrolyte (1 mol·L⁻¹) were added. -1 A LiPF6 aqueous solution (using EC, EMC, and DMC in a volume ratio of 1:1:1 as solvents) was used to cover a PP separator. Two drops of electrolyte were added, followed by a lithium sheet. A gasket and spring were then pressed on, and finally the positive electrode shell was placed on top. The battery was then encapsulated using a stamping machine at a pressure of 5 MPa for 10 seconds. The resulting coin cell was removed from the glove box and the surface residual electrolyte was wiped off, yielding a lithium-ion battery. After standing for 8 hours, the lithium-ion battery underwent rate and cycle performance tests. The results are shown below. Figure 6 .

[0067] The formula for calculating current is as follows:

[0068] I=ρ 电流 ·m·1000

[0069] Where m = m2 - m1.

[0070] Figure 6 The rate performance curves of lithium-ion batteries assembled using PT-MoS2-P123, MoS2-P123, PT-MoS2, and MoS2 samples prepared in Example 1 and Comparative Examples 1-3, respectively, as negative electrodes are shown. Figure 6 It can be seen that at current densities of 0.1, 0.2, 0.5, 1, 2, 5, and 0.1 C, the specific capacities of lithium-ion batteries assembled with PT-MoS2-P123 as the negative electrode are 5807, 5707, 5573, 5376, 5036, 4308, and 5859 mAh·g, respectively. -1 It exhibits excellent rate performance.

[0071] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a MoS2 self-supporting electrode, characterized in that, Includes the following steps: (1) Dissolve the molybdenum source, sulfur source and surfactant P123 in deionized water to obtain a precursor solution; (2) Carbon cloth was placed in a precursor solution and subjected to a hydrothermal reaction to obtain carbon cloth loaded with MoS2. (3) Plasma treatment was performed on the carbon cloth loaded with MoS2 to obtain a MoS2 self-supporting electrode.

2. The preparation method according to claim 1, characterized in that: The molybdenum source is ammonium molybdate and its hydrate.

3. The preparation method according to claim 1, characterized in that: The sulfur source is thioacetamide.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the molybdenum source, sulfur source and P123 is (0.8~1): (0.2~0.4): (0.8~1).

5. The preparation method according to claim 1, characterized in that: The hydrothermal reaction is carried out at a temperature of 170-190℃ for 16-20 hours.

6. The preparation method according to claim 1, characterized in that: The plasma treatment is carried out under normal temperature and pressure conditions, with a power of 40~60 W, a gas flow rate of 70~90 sccm, and a treatment time of 3~8 min; preferably, the gas used for plasma treatment is air.

7. A MoS2 self-supporting electrode obtained by the preparation method according to any one of claims 1 to 6.

8. The application of the MoS2 self-supporting electrode according to claim 7 in electrochemical energy storage.

9. A lithium-ion battery, characterized in that: The MoS2 self-supporting electrode as described in claim 7 is used as the negative electrode.

10. A supercapacitor, characterized in that: The MoS2 self-supporting electrode as described in claim 7 is used as the negative electrode.

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