Preparation method and application of carbon nanofiber loaded WSe2 / Dy-WO3 heterojunction electrode material

Abstract

The invention relates to a preparation method and application of a carbon nanofiber loaded WSe2 / Dy-WO3 heterojunction electrode material. The method comprises the following steps: taking a high-molecular polymer containing W and Dy bimetal salts as a spinning solution, obtaining carbon fiber loaded Dy-WO3 by using an electrostatic spinning-high-temperature calcination method, then selenizing the Dy-WO3 by using a vapor deposition (CVD) method, and constructing a WSe2 / Dy-WO3 heterogeneous interface by using the Se reaction amount and a carrier gas component. The obtained carbon nanofiber loaded WSe2 / Dy-WO3 heterojunction material is used as a positive electrode, so that the technical problems of high cost and low energy density of an electrode material in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical energy storage technology, and in particular to a flexible tungsten selenide / dysprosium-tungsten oxide (WSe2 / Dy-WO3) heterostructure electrode material for supercapacitors, and a preparation method and application thereof. Background Art

[0002] The over-exploitation and utilization of traditional fossil fuels have led to the depletion of resources, highlighting the urgent need for sustainable and renewable energy storage solutions. In this context, supercapacitors (SCs) have become promising candidates to meet the growing demand for efficient energy storage devices due to their high power density and fast charging and discharging capabilities. However, the relatively low energy density and limited cycle life of SCs remain the main obstacles to large-scale application. In recent years, flexible asymmetric supercapacitors (ASCs) assembled by combining pseudocapacitive and double-layer capacitor electrode materials have the advantages of flexibility and portability with high performance, showing great application potential in wearable electronic devices, flexible displays and other fields. In these application scenarios, energy storage devices are required not only to have good electrochemical properties, but also to be able to adapt to different mechanical deformations such as bending and folding without affecting their performance. Therefore, from the perspective of material design and preparation, the rational design and preparation of Faraday-type cathode materials is crucial to improving the energy density and cycle life of flexible ASCs, providing an important way to solve today's energy challenges.

[0003] In recent years, in view of the comprehensive consideration of material performance and cost, many studies have focused on exploring low-cost transition metal materials as substitutes for precious metals. Transition metals such as Fe, Co, Mo, Mn, and W have become key candidate materials in this field due to their excellent pseudocapacitive behavior. Among them, W-based compounds have outstanding performance in the field of pseudocapacitive materials, with good photoelectric response and high conductivity. For example, WO3, WS2, WSe2, etc. have emerged in the field of electrochemical energy storage by virtue of the advantages of polycrystalline structure properties. Among the existing invention patents, China's invention patent CN202410907274.2 discloses a WO3 / g-C3N4@WS2 ternary photocatalyst and its preparation method and application. By constructing a heterojunction, the electron transfer ability is enhanced, the recombination rate of electron-hole pairs is reduced, and the transient photocurrent is increased by about 18.18%. The specific surface area is 100.77 m 2 g -1, the degradation efficiency of Rhodamine B reached 97.9% under visible light for 15 min. This technology focuses on photocatalytic degradation based on the excellent photoelectric response of W-based materials, rather than the field of energy storage (such as SCs). The performance of the material in pseudocapacitance mechanism, conductivity and cycle stability has not been fully verified. Therefore, the development of multiphase W-based materials from photocatalysis to energy storage, combining pseudocapacitance with double-layer capacitance mechanism, and designing electrode materials with high energy density and long cycle life to fill the gap in the existing technology. Chinese invention patent CN106206071A discloses a high specific capacity WO3·H2O / PbO2 composite electrode and its preparation method and application. WO3·H2O and PbO2 work together to make the composite electrode have good pseudocapacitance characteristics. During the charge and discharge process, the charge is stored and released through redox reactions. The WO3·H2O / PbO2 electrode is 2mV s -1 At the scan rate, the maximum specific capacitance can reach 445F g -1 . However, although this technology WO3·H2O / PbO2 has excellent performance in specific capacitance, its PbO2 is toxic and does not meet the environmental protection requirements of green energy materials, and the subsequent recycling and treatment costs are high; in addition, the shortcomings of the synthesis method and cycle life make it difficult to meet the adaptability requirements of flexible SCs to mechanical deformations such as bending and folding. Therefore, designing environmentally friendly, low-cost and excellent mechanically flexible SCs electrode materials to fill the gap in environmentally friendly flexible energy storage technology is an urgent problem to be solved. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method and application of carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction electrode materials in view of the limitations of the current technology. The method uses a high molecular polymer containing W and Dy bimetallic salts as a spinning solution, uses an electrospinning-high temperature calcination method to obtain carbon fiber-loaded Dy-WO3, and then selenizes Dy-WO3 by a vapor deposition (CVD) method. During the CVD process, only when the appropriate Se reaction amount and the carrier gas component (H2 / Ar (5%+95%), 80sccm) reach a balance point can a WSe2 / Dy-WO3 heterogeneous interface be constructed to achieve electron redistribution and improve the electrochemical reaction kinetics. In addition, the carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction material is used as a positive electrode, and pure PCNFs are prepared as a negative electrode, TEAOH-KOH / PVA is used as a gel electrolyte, and a flexible ASC is assembled.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: A method for preparing a carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction electrode material, the method comprising the following steps: Step 1: Preparation of Dy-WO3 flexible material (1) Preparation of spinning solution: PAN and AMT were added to the mixed solvent and stirred at room temperature for 2-4 h until dissolved. Then, Dy(NO3)3·6H2O was added and stirred at room temperature for 20-30 h, followed by ultrasonic treatment for 20-40 min to obtain a light yellow transparent spinning solution. Among them, 0.05-0.3 g PAN, 1.0-5.0 g AMT and 0.01-0.05 g Dy(NO3)3·6H2O were added to every 10 g of mixed solvent; the composition of the solvent in the mixed solution was PVP and DMF, and the mass ratio of the two was 1:9; (2) Electrospinning: The spinning solution was loaded into a syringe for electrospinning. The fibers were collected using a three-dimensional dynamic receiving device with an amplitude adjustment range of 5 to 15 mm. Thus, a Dy(NO3)3-AMT / PAN-PVP polymer film accumulated on the aluminum foil was obtained. The film was then placed in a vacuum oven at 50 to 70 °C for 6 to 8 h. The electrospinning conditions were as follows: receiving distance 18-22 cm, voltage 13-17 kV adjustable voltage, fluid push speed 0.3-0.7 mL h -1 , drum speed 70~80 r min -1 ; The ambient temperature was maintained at 25±3 ℃ and the humidity was controlled at 40±5 %rh; (3) Heat treatment: Place the film that has been treated in the oven in the center of a tube furnace and heat the material obtained in the previous step at 1~3 ℃ min -1 The temperature was raised to 200-300 °C at a rate of 100 °C and maintained in an air atmosphere for 0.5-1.5 h for pre-oxidation. After the pre-oxidation, Ar gas was introduced as a protective gas and the temperature was raised to 500-700 °C at the same rate of 100 °C and maintained for 1-3 h, thereby finally obtaining a Dy-WO3 flexible material. Step 2: Preparation of WSe2 / Dy-WO3 materials: (1) Material placement: First, Dy-WO3 was placed in a quartz boat and placed downstream of the CVD tube. Second, Se powder (m2) was loaded into a ceramic crucible and placed flat in another boat, which was placed upstream of the CVD tube and 28-32 cm away from Dy-WO3. Among them, the mass ratio of Dy-WO3 and Se powder is =1:0.50~1.00; (2) Reaction process: In H2 / Ar (5%+95%) atmosphere, maintain a constant flow rate of 60~100 sccm and a temperature of 8~12℃ min -1The downstream temperature zone was rapidly raised to 700-900 °C at a heating rate, while the upstream temperature zone was maintained at 350-450 °C, and the reaction was continued for 90-150 min. After the reaction, the material was cooled in an Ar atmosphere to finally obtain WSe2 / Dy-WO3 supported by carbon nanofibers.

[0006] Application of the carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction electrode material prepared by the method as a positive electrode material in flexible SCs; The specific steps include: (1) Preparation of WSe2 / Dy-WO3 electrode The WSe2 / Dy-WO3 flexible electrode material was sandwiched between two sheets of nickel foam (1×1 cm 2 ) and prepare the electrode sheet at a pressure of 5 to 20 MPa; The thickness of the WSe2 / Dy-WO3 flexible electrode material is 0.1-0.4 mm; (2) Preparation of TEAOH-KOH / PVA gel electrolyte Add polyvinyl alcohol to the mixed solution to dissolve, then add KOH, and stir at 80-100°C for 4-6 hours; then, pour the obtained liquid gel into a mold, and freeze at -20°C for 8-12 hours to obtain a solid TEAOH-KOH / PVA gel electrolyte; Among them, 2-3 g of polyvinyl alcohol and 1-5 g of KOH are added to every 20-30 g of the mixed solution; the composition of the mixed solution is TEAOH and deionized water; the mass ratio of the two is 3:5; (3) Assembling ASC of PCNFs / / WSe2 / Dy-WO3 With WSe2 / Dy-WO3 as the positive electrode, PCNFs as the negative electrode, and TEAOH-KOH / PVA as the gel electrolyte, button-type ASCs and flexible solid-state soft packages were assembled.

[0007] The essential features of the present invention are: In current technology, there is a scheme to prepare in-situ Ce-doped WO3 carbon nanofibers (Ce / WO3-CNFs) by electrospinning and calcination technology. The introduction of Ce increases the lattice spacing of WO3 (XRD shows that the (002) crystal plane spacing increases from 0.382 nm to 0.401 nm), thereby enhancing the electrolyte permeability and electron transfer efficiency. The specific capacitance of Ce / WO3-CNFs reaches 407 F g -1 (0.5A g -1 ), which is better than undoped WO3-CNFs (322 F g -1). However, due to the polycrystalline structure and multiple oxidation states of WO3, the advantages of WO3 in SCs cannot be fully utilized simply by high temperature treatment and rare earth Ce modification.

[0008] The present invention constructs a WSe2 / Dy-WO3 built-in electric field that induces heterogeneous interface charge redistribution through a simple and easy two-step method of electrospinning combined with CVD, forming metal-like materials with different energy level structures and electronic configurations to be stacked or spliced ​​on the heterogeneous interface, inducing charge redistribution and transfer at the interface. WSe2 / Dy-WO3 has the advantage of being "anchored" in a one-dimensional nanostructure phase structure and an interfacial electric field, which has the advantage of regulating electronic structure, promoting electron redistribution, and improving electrochemical reaction kinetics. Among them, each step cooperates with each other to achieve a specific structure and performance of the material. In the preparation process of Dy-WO3 flexible material, PVP, PAN, AMT and Dy(NO3)3·6H2O are mixed and then electrospun to form a film, and the electrospinning parameters affect the morphology and structure of the film. The pre-oxidation and calcination process changes the chemical composition and crystal structure of the material, so that it forms a Dy-WO3 flexible material with specific properties. When preparing WSe2 / Dy-WO3 materials, different temperature zones and gas atmospheres in the CVD tube are used to make Dy-WO3 react with Se powder. Different mass ratios will lead to different proportions of each component in the material, which in turn affects the microstructure and properties of the material, providing material selection with different characteristics for subsequent applications in energy storage and other fields.

[0009] The beneficial effects of the present invention are: The present invention constructs a WSe2 / Dy-WO3 nanofiber heterostructure by combining electrospinning with a CVD method, while giving full play to the similar electronegativity characteristics of the O element and the Se element, regulating the electron migration behavior and improving the electrochemical reaction kinetics.

[0010] WSe2 / Dy-WO3 electrode at a current density of 0.5 A g -1 When the specific capacitance is 679.23 F g -1 , better than Dy-WO3 (557.28 F g -1 )、L WSe / Dy-WO3(611.22 F g -1 ) and H WSe / Dy-WO3(583.22 F g -1 ). Based on WSe2 / Dy-WO3 as the positive electrode and PCNFs as the negative electrode, button-type ASC and flexible solid-state soft package were assembled respectively. The ASC has a high energy density (when the power density is 362.54 W kg -1 Its energy density reaches 46.33 Wh kg -1). Compared with the solution chemistry method reported in the Journal of Colloid And Interface Science in 2024, a WO3 nano-petal-like structure with a surface morphology similar to that of a marigold was grown on a stainless steel substrate. -1 The specific capacitance at the scan rate is 271.67±9.37 F g -1 The assembled solid-state SCs device has a power density of 131.53±4.41 W kg -1 When the energy density is only 6.26±0.21 Wh kg -1 With Dy-WO3 / PCNFs as the positive electrode and CNFs as the negative electrode, the assembled ASC has an energy density of only 29.8 Wh kg at a power density of 363.48 W kg-1. -1 Therefore, the present invention adopts electrospinning combined with in-situ CVD technology to prepare carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction with high electrochemical performance to solve the technical problems of high cost and low energy density of electrode materials in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the SEM image of the Dy(NO3)3-AMT / PAN-PVP polymer film obtained by electrospinning in Example 1.

[0012] Figure 2 This is the SEM image of the Dy-WO3 flexible material obtained by heat treatment in Example 1.

[0013] Figure 3 This is the SEM image of the WSe2 / Dy-WO3 flexible material obtained by vapor deposition selenization treatment in Example 3.

[0014] Figure 4 It is the xrd of Dy-WO3 and WSe2 / Dy-WO3 obtained in Examples 1 and 3.

[0015] Figure 5 is the TEM of WSe2 / Dy-WO3 obtained in Example 3; wherein, Figure 5 (a) TEM of WSe2 / Dy-WO3 loaded on carbon nanofibers. Figure 5 (b, c) are HR-TEM images of WSe2 / Dy-WO3, showing the (002) crystal plane of WSe2 and the (002) crystal plane of WO3. The lattice spacings of the (002) crystal plane of WSe2 and the (002) crystal plane of WO3 are 0.68 nm and 0.38 nm, respectively. It is worth noting that WSe2 / Dy-WO3 exhibits a clear lattice interface.

[0016] Figure 6 The electrochemical performance diagrams of Dy-WO3, L WSe / Dy-WO3, WSe2 / Dy-WO3 and H WSe / Dy-WO3 obtained in Examples 1, 2, 3 and 4 are shown.

[0017] Figure 7 This is the energy density diagram of the ASC assembled by PCNFs / / WSe2 / Dy-WO3 obtained in Example 3.

[0018] Figure 8 A 3.6 V LED illuminates a button-type ASC assembled from three PCNFs / / WSe2 / Dy-WO3 connected in series.

[0019] Fig. 9 Schematic diagram of solid-state ASC soft package assembled from PCNFs / / WSe2 / Dy-WO3.

[0020] Fig.10 This is the TEAOH-KOH / PVA solid gel obtained in Example 3. DETAILED DESCRIPTION

[0021] Embodiment 1: A method for preparing a carbon nanofiber-loaded Dy-WO3 electrode material, the method comprising the following steps: (1) Preparation of Dy(NO3)3-AMT / PAN-PVP polymer fiber membrane Solution preparation: 1.0 g polyvinyl pyrrolidone (PVP) and 0.1 g polyacrylonitrile (PAN) were dissolved in 9 g N,N-dimethylformamide (DMF), stirred for 3 h until completely dissolved, and then 2 g ammonium metatungstate (AMT) and 0.02 g dysprosium nitrate hexahydrate (Dy(NO3)3·6H2O) were added. The mixture was stirred at room temperature for 24 h, followed by ultrasonic treatment for 30 min to obtain a light yellow transparent spinning solution.

[0022] Electrospinning: The spinning solution was placed into a 10 ml plastic syringe for electrospinning (electrospinning equipment: Nafiber BS-200). The fibers were collected using a three-dimensional dynamic receiving device, and the electrospinning conditions were set at a receiving distance of 20 cm, a voltage of 15 kV, and a pushing speed of 0.5 mL h -1 , spinning amplitude 10 mm, drum speed 70 r min -1 The ambient temperature was maintained at 25±3°C and the humidity was controlled at 40±5%rh; thus, a Dy(NO3)3-AMT / PAN-PVP polymer film accumulated on the aluminum foil was obtained. The film was placed in a vacuum oven at 60°C for 6 h.

[0023] (2) Preparation of Dy-WO3 flexible materials Heat treatment: Place the film treated in the oven in the center of a tube furnace and heat it at 2 °C min -1 The material was heated to 250 °C at a heating rate of 100 °C and kept in air atmosphere for 1 h for pre-oxidation. After the pre-oxidation, Ar gas was introduced as a protective gas and the material was heated to 600 °C at the same heating rate and kept for 2 h. Finally, Dy-WO3 flexible material was obtained. -1 The specific capacitance of Dy-WO3 electrode is 557.28 F g -1 The Dy-WO3 obtained in Example 1 was used as a blank experiment to explore the Seization of the CVD process.

[0024] Electrochemical testing instrument: Electrochemical workstation-CHI660E-Shanghai Chenhua Instrument Co., Ltd. Electrochemical performance test method of three electrodes: The electrochemical performance of the electrodes was evaluated in 4 M KOH electrolyte. First, cyclic voltammetry (CV) was tested to determine the CV test voltage window (0-0.6 V). The test scan rate range was changed to 0.05, 0.03, 0.02, 0.01, 0.005, and 0.002 V s -1 , test 2 cycles at each scan rate; constant current charge and discharge GCD curve, determine the test voltage window (0~0.5 V), change the test current density to 0.5, 0.8, 1, 3, 5, 8, 10 A g -1 , charge and discharge twice at each current density; the electrochemical impedance spectroscopy (EIS) test frequency range is 0.01~10 5 Hz, at a certain open circuit voltage, the sinusoidal AC current amplitude is 0.05 V.

[0025] Embodiment 2: A method for preparing a carbon nanofiber-loaded LWSe / Dy-WO3 electrode material, the method comprising the following steps: Step 1: Preparation of Dy-WO3 flexible material, the steps are the same as those in Example 1; Step 2: Preparation of L WSe / Dy-WO3 materials Material placement: First, Dy-WO3 (m1) was placed in a quartz porcelain boat and placed downstream of the CVD tube. Second, Se powder (m2) was loaded into a ceramic crucible and placed flat in another porcelain boat, which was placed upstream of the CVD tube at a distance of 32 cm from Dy-WO3. The mass ratio of Dy-WO3 and Se powder was m1:m2=1:0.50.

[0026] Reaction process: In H2 / Ar (volume ratio 5% + 95%) atmosphere, maintain a constant flow rate of 100 sccm and heat at 10 ℃ min -1The downstream temperature zone was quickly raised to 800 °C at a heating rate of 1.5 °C, while the upstream temperature zone was kept at 400 °C for 90 min. After the reaction, the material was cooled in an Ar atmosphere to obtain LWSe / Dy-WO3 electrode material. -1 The specific capacitance is 583.22 F g -1 .

[0027] Embodiment 3: A method for preparing a carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction, the method comprising the following steps: Step 1: Preparation of Dy-WO3 flexible material, the steps are the same as those in Example 1; Step 2: Preparation of carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction Material placement: First, Dy-WO3 (m1) was placed in a quartz porcelain boat and placed downstream of the CVD tube. Second, Se powder (m2) was loaded into a ceramic crucible and placed flat in another porcelain boat, which was placed upstream of the CVD tube at a distance of 30 cm from Dy-WO3. The mass ratio of Dy-WO3 and Se powder was m1:m2=1:0.75.

[0028] Reaction process: In H2 / Ar (5%+95%) atmosphere, maintain a constant flow rate of 80 sccm and heat at 10 ℃ min -1 The downstream temperature zone was quickly raised to 800 °C at a heating rate of 1.5 °C, while the upstream temperature zone was kept at 400 °C for 120 min. After the reaction, the material was cooled in an Ar atmosphere to obtain a carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction material. -1 The specific capacitance is 679.23 F g -1 .

[0029] Embodiment 4: A method for preparing a carbon nanofiber-loaded HWSe / Dy-WO3 electrode material, the method comprising the following steps: Step 1: Preparation of Dy-WO3 flexible material, the steps are the same as those in Example 1; Step 2: Preparation of H WSe / Dy-WO3 materials Material placement: First, Dy-WO3 (m1) was placed in a quartz porcelain boat and placed downstream of the CVD tube. Second, Se powder (m2) was loaded into a ceramic crucible and placed flat in another porcelain boat, which was placed upstream of the CVD tube with a distance of 28 cm from Dy-WO3. The mass ratio of Dy-WO3 and Se powder was m1:m2=1:1.00.

[0030] Reaction process: In H2 / Ar (5%+95%) atmosphere, maintain a constant flow rate of 60 sccm and heat at 10 ℃ min -1 The downstream temperature zone was quickly raised to 800 °C at a heating rate of 1.5 °C, while the upstream temperature zone was kept at 400 °C for 150 min. After the reaction, the material was cooled in an Ar atmosphere to obtain H WSe / Dy-WO3 electrode material. -1 The specific capacitance is 611.22 F g -1 .

[0031] The carbon nanofiber-loaded WSe2 / Dy-WO3 electrode material with the best electrochemical performance obtained in Example 3 was used as the positive electrode to assemble SCs: (1) Preparation of WSe2 / Dy-WO3 electrode sheet A 0.2 mm thick WSe2 / Dy-WO3 flexible electrode material (0.5 mg) was sandwiched between two sheets of nickel foam (1×1 cm 2 ) and prepared the electrode sheets under 10 MPa pressure (benchtop powder tablet press FYC-25). The electrochemical performance of the three-electrode system was investigated in 4 M KOH electrolyte, with WSe2 / Dy-WO3, platinum mesh and Hg / HgO electrodes as working electrode, counter electrode and reference electrode, respectively. The CV, GCD and EIS were tested and recorded on an electrochemical workstation (CHI760E). The specific capacitance (C, F·g -1 ) is calculated as follows:

[0032] Where C (F g -1 ) is the specific capacity of the electrode, I is the discharge current, Δt is the discharge time, ΔV is the potential window during the GCD process, and m is the mass of the active material.

[0033] (2) Preparation of negative electrode PCNFs materials and electrode sheets Solution preparation: 0.6 g PVP and 0.4 g PAN were dissolved in 9 g DMF and stirred for 24 h until completely dissolved to obtain a colorless and transparent spinning solution.

[0034] The electrospinning conditions were set in accordance with the preparation process of Dy(NO3)3-AMT / PAN-PVP polymer film in Example 1 above, and a PAN-PVP polymer film was obtained.

[0035] The heat treatment conditions were consistent with the preparation process of Dy-WO3 material in Example 1 above, and PCNFs were obtained as negative electrode materials. -1The specific capacitance is 161 F g -1 .

[0036] The PCNFs material was sandwiched between two sheets of nickel foam (1×1 cm 2 ) and prepare the negative electrode sheet under a pressure of 10 MPa.

[0037] (3) Preparation of TEAOH-KOH / PVA gel electrolyte 2.5 g PVA was added to a mixture containing 9 g TEAOH and 15 g deionized water, heated and stirred at 90 °C until dissolved, and then 3 g KOH was added. The heating was continued for 4 to 6 hours, at which time the solution was yellow and clear. Subsequently, the liquid gel was poured into a mold, frozen at -20 °C for 8 to 12 hours, and taken out to obtain a solid TEAOH-KOH / PVA gel electrolyte.

[0038] (4) ASC was assembled with WSe2 / Dy-WO3 electrode as the positive electrode and PCNFs as the negative electrode. The mass calculation formula of the two electrodes is as follows:

[0039] in, is the mass of active material in the positive electrode, is the mass of active material in the negative electrode. and is the specific capacitance of the positive electrode and the negative electrode. and are the potential ranges of the positive electrode and the negative electrode, respectively. After balancing the charge capacity, the mass ratio of the positive electrode to the negative electrode working electrode material is controlled at 2.83.

[0040] (5) Two-electrode system test: First, CV was performed to determine the voltage window of the CV test. The test scan rate range was 0.05, 0.03, 0.02, 0.01, and 0.005 V s -1 , test 2 cycles at each scan rate; constant current charge and discharge GCD curve, determine the test voltage window, current density is 0.5, 0.8, 1, 3, 5, 8, 10 A g -1 , charge and discharge twice at each current density.

[0041] The energy density (E) and power density (P) of ACS were calculated by:

[0042]

[0043] (6) Assembling PCNFs / / WSe2 / Dy-WO3 ASC With WSe2 / Dy-WO3 as the positive electrode, PCNFs as the negative electrode, and TEAOH-KOH / PVA as the gel electrolyte, button-type ASCs and flexible solid soft packs were assembled. The introduction of TEAOH in the electrolyte can strengthen the hydrogen bonding effect and has a water retention function, thereby extending the service life of SCs.

[0044] In summary, the present invention is based on the structural characteristics of WO3 with polycrystalline morphology, and the crystal structure of WO3 is regulated by introducing rare earth elements to improve its reaction activity in the electrochemical process. Among the numerous rare earth elements, Dy has a large number of outer electron orbits and a large number of unpaired 4f orbital electrons, which can provide a more efficient electron conduction path, thereby improving the storage capacity of Dy-WO3. While deeply exploring the excellent performance of WO3 in the field of pseudocapacitive materials, researchers have noticed that from the perspective of element synergy, non-metallic elements such as S, Se, and P can often induce changes in physical and chemical properties when combined with transition metal compounds. By continuing to modify the precursor, the electronic structure of the material can be effectively regulated, so as to prepare a composite electrode with better electrochemical performance. Thus, the introduction of non-metallic elements forms a chemical bond between it and the metal atom, and this process forms a metal-like material with different energy level structures and electronic configurations to be stacked or spliced ​​on a heterogeneous interface. Therefore, in view of the photoelectric response characteristics of WO3 and the similarity and gradual change of chemical properties between elements of the same group, we will select Se elements from the same main group as O elements and with relatively strong electronegativity to further modify Dy-WO3, and construct WSe2 / Dy-WO3 heterojunction for flexible electrode materials with excellent performance. WSe2 / Dy-WO3 electrode has excellent performance at a current density of 0.5 A g -1 The specific capacitance is the largest at 679.23 F g -1 , which is better than Dy-WO3 electrode (557.28 F g -1 ), L WSe / Dy-WO3 electrode (583.22 F g -1 ) and H WSe / Dy-WO3 electrode (611.22 F g -1 ).

[0045] Matters not covered by the present invention are known technologies.

Claims

1. A method for preparing a carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction electrode material, characterized in that: The method comprises the following steps: Step 1: Preparation of Dy-WO3 flexible material (1) Preparation of spinning solution: PAN and AMT were added to the mixed solvent and stirred at room temperature for 2-4 h until dissolved. Then, Dy(NO3)3·6H2O was added and stirred at room temperature for 20-30 h, followed by ultrasonic treatment for 20-40 min to obtain a light yellow transparent spinning solution. Among them, 0.05-0.3 g PAN, 1.0-5.0 g AMT and 0.01-0.05 g Dy(NO3)3·6H2O were added to every 10 g of mixed solvent; the composition of the solvent in the mixed solution was PVP and DMF, and the mass ratio of the two was 1:9; (2) Electrospinning: The spinning solution is loaded into a syringe for electrospinning to obtain a Dy(NO3)3-AMT / PAN-PVP polymer film accumulated on an aluminum foil, and then the film is placed in a vacuum oven at 50-70°C for 6-8 h; The electrospinning conditions were as follows: receiving distance 18-22 cm, voltage 13-17 kV adjustable voltage, fluid push speed 0.3-0.7 mL h -1 , drum speed 70~80 r min -1 ; The ambient temperature was maintained at 25±3 ℃ and the humidity was controlled at 40±5 %rh; (3) Heat treatment: Heat the material obtained in the previous step at 1~3 ℃ min -1 The temperature was raised to 200-300 °C at a rate of 100 °C and maintained in an air atmosphere for 0.5-1.5 h for pre-oxidation. After the pre-oxidation, Ar gas was introduced as a protective gas and the temperature was raised to 500-700 °C at the same rate of 100 °C and maintained for 1-3 h, thereby finally obtaining a Dy-WO3 flexible material. Step 2: Preparation of WSe2 / Dy-WO3 materials: (1) Material placement: First, Dy-WO3 was placed in a quartz boat and placed downstream of the CVD tube. Second, Se powder was loaded into a ceramic crucible and placed flat in another boat, which was placed upstream of the CVD tube and 28-32 cm away from Dy-WO3. Among them, the mass ratio of Dy-WO3 and Se powder is =1:0.50~1.00; (2) Reaction process: In H2 / Ar (5%+95%) atmosphere, maintain a constant flow rate of 60~100 sccm and a temperature of 8~12 ℃min -1 The downstream temperature zone was raised to 700-900 °C at a heating rate, while the upstream temperature zone was maintained at 350-450 °C, and the reaction was continued for 90-150 min. After the reaction, the temperature was lowered in an Ar atmosphere to finally obtain WSe2 / Dy-WO3 supported on carbon nanofibers.

2. The method for preparing the carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction electrode material according to claim 1, characterized in that: In the electrospinning of step 1, the fibers are collected using a three-dimensional dynamic receiving device with an amplitude adjustment range of 5 to 15 mm.

3. Application of the carbon nanofiber-loaded WSe2 / Dy-WO3 heterojunction electrode material prepared by the method of claim 1, characterized in that: Used as cathode materials in flexible SCs.

4. The use according to claim 3, characterized in that it comprises the following steps: (1) Preparation of WSe2 / Dy-WO3 electrode: The WSe2 / Dy-WO3 flexible electrode material was sandwiched between two sheets of nickel foam and the electrode sheet was prepared under a pressure of 5-20 MPa; The thickness of the WSe2 / Dy-WO3 flexible electrode material is 0.1-0.4 mm; (2) Preparation of TEAOH-KOH / PVA gel electrolyte: Add polyvinyl alcohol to the mixed solution to dissolve, then add KOH, and stir at 80-100°C for 4-6 hours; then, pour the obtained liquid gel into a mold, and freeze at -20°C for 8-12 hours to obtain a solid TEAOH-KOH / PVA gel electrolyte; in, Add 2-3 g polyvinyl alcohol and 1-5 g KOH to every 20-30 g of the mixed solution; the composition of the mixed solution is TEAOH and deionized water; the mass ratio of the two is 3:5; (3) Assembling ASC of PCNFs / / WSe2 / Dy-WO3 With WSe2 / Dy-WO3 as the positive electrode, PCNFs as the negative electrode, and TEAOH-KOH / PVA as the gel electrolyte, button-type ASCs and flexible solid-state soft packages were assembled.

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