Hydrothermal-electrodeposition method for preparing selenite-sulfide composite nanomaterials and application thereof

Abstract

This invention provides a method for preparing a selenite-sulfide nanocomposite material. Nickel selenite is grown in situ on nickel-plated carbon cloth using a hydrothermal method, followed by electrodeposition of transition metal sulfides onto its surface. Selenite, as a reinforcing phase in the positive electrode material of a supercapacitor, improves the conductivity of the composite material and releases selenate ions, which, along with sulfate ions released from the sulfides, adsorb onto the material surface, promoting redox kinetics in the electrochemical process. The prepared selenite-sulfide composite nanoelectrode material exhibits excellent supercapacitor performance at a current density of 1 A g. ‑1 At that time, its specific capacity was 3509 F g. ‑1 An asymmetric supercapacitor composed of commercially available activated carbon at 844 W / kg ‑1 The power density reached 141Wh / kg. ‑1 High energy density. This supercapacitor exhibits good cycle stability at 5A g. ‑1 Under these conditions, after 25,000 cycles, the capacity retention rate was 100.2%.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage devices, and specifically relates to a method for preparing selenite-sulfide composite nanomaterials by hydrothermal-electrodeposition, and its application in supercapacitors. Background Technology

[0002] Energy shortages have driven the development of electrochemical energy storage devices. Among them, supercapacitors have attracted widespread attention due to their long cycle life, rapid charging and discharging, and high power density. However, their relatively low energy density limits their further development in practical applications. Asymmetric supercapacitors are an effective way to bridge the gap between capacitors and batteries. By increasing the battery voltage and enhancing the specific capacity of electrode materials, the energy density of asymmetric supercapacitors for practical applications can be effectively improved. The performance of asymmetric supercapacitors is directly related to the performance of electrode materials. Therefore, designing a cathode material with high capacity and long cycle life has become a focus of attention.

[0003] Transition metal compounds possess high theoretical capacitance and are considered promising cathode materials for supercapacitors. The performance of transition metal cathode materials in alkaline electrolytes is limited by two factors: first, the material's conductivity; and second, the redox reaction kinetics during the electrochemical process. Therefore, both aspects should be considered when constructing a suitable cathode material structure.

[0004] This invention utilizes transition metal sulfides as the primary active material. A simple hydrothermal-electrodeposition method is employed to prepare selenite-sulfide composite nanomaterials, constructing a heterostructure of selenite and sulfide. This significantly improves the material's conductivity and provides an additional conductive pathway during electrochemical reactions. The adsorption of sulfate and selenate groups released during electrochemical processes on the material surface promotes the desorption of hydroxide ions, enhancing the electrode reactivity. The supercapacitor performance of this composite material is significantly improved, exhibiting high specific capacitance, excellent rate performance, and long-term cycle stability. Summary of the Invention

[0005] The technical problem to be solved by this invention is to synthesize selenite-sulfide composite nanomaterials by introducing selenite as an electrochemical performance-enhancing phase using a hydrothermal-electrodeposition method. Ultimately, these nanomaterials are used as electrode materials for supercapacitors, and their electrochemical performance is investigated.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] Nickel sulfate and boric acid were dissolved in deionized water. After cleaning the carbon cloth, it was used as the working electrode in the above solution for electrochemical deposition. The sample was then removed and dried to obtain nickel-plated carbon cloth. The nickel-plated carbon cloth was placed in a mixed solution of selenite, sodium bicarbonate, nickel sulfate, and ammonia, heated, and cooled to room temperature. The sample was then removed, cleaned, and dried to obtain nickel-plated carbon cloth with in-situ grown nickel selenite. This sample was used as the working electrode, and a mixed solution of cobalt nitrate, nickel nitrate, manganese chloride, thioacetamide, and potassium chloride was used as the electrolyte for electrochemical deposition. Finally, the sample was rinsed multiple times with deionized water to remove excess impurities and inorganic salts, and then dried in a vacuum oven. The resulting selenite-sulfide composite nanomaterial was used as an electrode material for supercapacitors.

[0008] (1) Compared with the prior art, the beneficial effects of the present invention are reflected in the fact that by constructing a selenite-sulfide composite nanostructure, there is an obvious interfacial interaction between the two phases, which is conducive to the directional conduction of electrons and significantly enhances the conductivity of the material.

[0009] (2) During the charging and discharging process, the selenite-sulfide composite nanostructure is transformed into transition metal hydroxide and continues to undergo electrochemical reactions. The released sulfate and selenate ions are adsorbed on the surface of the transition metal hydroxide, which is conducive to the adsorption of hydroxide ions and the removal of proton hydrogen, thus enhancing the redox reaction kinetics of the material.

[0010] (3) The hydrothermal-electrodeposition method for synthesizing selenite-sulfide composite nanomaterials exhibits high specific capacitance, high energy density, and long cycle life. This opens up new avenues for the application of asymmetric capacitors in the field of energy storage. Attached Figure Description

[0011] Figure 1 These are scanning electron microscope (SEM) images of the composite nanomaterials prepared in Examples 1-2.

[0012] Figure 2 The images show the XRD patterns of the composite nanomaterials prepared in Examples 1-2.

[0013] Figure 3 The image shows the XPS analysis of the selenite-sulfide composite nanomaterial prepared in Example 2.

[0014] Figure 4 The images show the EIS analysis results of the composite nanomaterials prepared in Examples 1-2.

[0015] Figure 5 The specific capacitance performance of the selenite-sulfide composite nanomaterial prepared in Example 2 is shown.

[0016] Figure 6The power density-energy density curve is shown for the supercapacitor assembled from the selenite-sulfide composite nanomaterials prepared in Example 2.

[0017] Figure 7 The supercapacitor assembled from the selenite-sulfide composite nanomaterials prepared in Example 2 was tested at 5Ag. -1 Cycle life of a supercapacitor measured at current density. Detailed Implementation

[0018] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0019] Example 1

[0020] After ultrasonic treatment, the carbon cloth was washed with 2M hydrochloric acid solution, ethanol, and deionized water, respectively. First, H₂BO₃ (1M) and NiSO₄·6H₂O (0.5M) were dissolved in 200ml of deionized water with magnetic stirring. Then, using the above solution as the electrolyte, the treated carbon cloth as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode as the counter electrode, a constant voltage charging at -1.1V for 2 hours was used to obtain nickel-plated carbon cloth. Ni(NO₃)₂6H₂O (5mM), Co(NO₃)₂·6H₂O (5mM), MnCl₂ (5mM), KCl (5mM), and TAA (1M) were dissolved in 200ml of deionized water with magnetic stirring. Then, using the above solution as the electrolyte, the nickel-plated carbon cloth as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode as the counter electrode, a constant voltage charging at -1.2V to 0.3V for 5mVs was used. -1 The scanning rate was determined by cyclic voltammetry for six cycles to electrodeposit transition metal sulfides. Finally, the samples were rinsed with deionized water and ethanol and dried at 80°C to obtain the final samples.

[0021] Example 2

[0022] After obtaining the nickel-plated carbon cloth, NiSO4 (0.256 mM), H2SeO3 (0.5 mM), and NaHCO3 (0.8 mM) were dissolved in 100 mL of deionized water by magnetic stirring. The nickel-plated carbon cloth was then added to the prepared reaction mixture. The solution was then transferred to a Teflon-lined stainless steel autoclave, heated to 90 °C over 12 hours, and maintained at 90 °C for 12 hours. Finally, the obtained in-situ grown nickel-selenite nickel-plated carbon cloth was rinsed with deionized water and ethanol. The in-situ grown nickel-selenite nickel-plated carbon cloth was used as the working electrode for the subsequent electrodeposition of transition metal sulfides. The remaining processing was the same as in Example 1.

[0023] like Figure 1 As shown in the scanning electron microscope (SEM) images, Examples 1 and 2 exhibit nanosheets uniformly grown on carbon fibers. Figure 2 XRD patterns of the composite materials from two embodiments are shown. In both embodiments, a broad peak at approximately 26° belonging to the carbon cloth and characteristic diffraction peaks of the nickel layer at 44.5° and 51.8° are visible. Example 2 also shows clear diffraction peaks of nickel selenite, which was well preserved during the electrodeposition of sulfides. Figure 3 XPS analysis images of the composite materials prepared in Examples 1 and 2 show the presence of Ni, Co, Mn, S, O, and C, with Se also present in Example 2. In conclusion, this hydrothermal-electrodeposition technique can successfully construct selenite-sulfide composite nanostructures, significantly improving the electrochemical performance of the electrode materials by enhancing their conductivity and redox reaction kinetics. This provides a new method for preparing electrode materials with excellent electrochemical performance.

[0024] Application Example 1

[0025] Using Example 2 as the working electrode, a platinum sheet electrode as the counter electrode, a mercuric oxide electrode as the reference electrode, and 1 MkOH solution as the electrolyte, the single-electrode electrochemical performance was tested using a CHI660 electrochemical workstation. The test results are as follows: Figure 4-5 As shown. Figure 4 The EIS spectra of Examples 1 and 2 are shown. The internal resistance, charge transfer resistance and diffusion resistance of the electrode material prepared in Example 2 are significantly reduced. Figure 5 The specific capacitance performance of Example 2 is shown at a current density of 1 A g. -1 It has 3509F g -1 High specific capacitance, even at 100A g -1 Even at high current densities, it still exhibits 1961 F g. -1 The specific capacitance was determined. Using Example 2 as the positive electrode, commercial activated carbon as the negative electrode, and 1M KOH solution as the electrolyte, an asymmetric supercapacitor was assembled. Its electrochemical performance was tested using a CHI660 electrochemical workstation. The test results are as follows: Figure 6-7 As shown. Figure 6 The power density-energy density curve of the device is shown, and the results indicate that at 844 W kg... -1 Its energy density can reach 141Wh kg at a power density of [value missing]. -1 This demonstrates excellent electrochemical performance. Cycle life, as one of the indicators for evaluating the performance of energy storage devices, such as... Figure 7 As shown, the device is at 5A g -1After 25,000 charge-discharge cycles at the given current density, it exhibits excellent reversibility and a cycle efficiency of 100.6%.

[0026] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a selenite-sulfide composite nanomaterial, characterized in that... It includes the following steps: (a) Preparation of nickel nanoarray on carbon cloth surface: After cleaning the carbon cloth, 1 mol / L boric acid and 0.5 mol / L nickel sulfate hexahydrate were dissolved in deionized water to prepare an electrolyte. The carbon cloth was used as the working electrode and charged at a constant voltage of -1.1V for 2 hours to obtain nickel-plated carbon cloth. (b) In-situ growth of nickel selenite layer: Nickel sulfate hexahydrate, selenite and sodium bicarbonate were dissolved in deionized water. The nickel-plated carbon cloth obtained in step (a) was placed in the prepared reaction mixture and transferred to a stainless steel autoclave with Teflon lining for hydrothermal reaction. The resulting sample was rinsed with deionized water and dried to obtain nickel-plated carbon cloth with nickel selenite grown on the surface. (c) Preparation of transition metal sulfides: Using the nickel-plated carbon cloth with nickel selenite grown on the surface obtained in step (b) as the working electrode, transition metal sulfides are grown by electrodeposition to obtain selenite-sulfide composite nanomaterials.

2. The method for preparing selenite-sulfide composite nanomaterials according to claim 1, characterized in that, In step (c): Cobalt sulfate hexahydrate, nickel sulfate hexahydrate, manganese chloride, thioacetamide, and potassium chloride are added to deionized water to prepare an electrolyte. Nickel-plated carbon cloth with nickel selenite grown on its surface is used as the working electrode. The electrolyte is scanned for 6 cycles at a scan rate of 5 mV / s under -1.2 V to 0.3 V to obtain selenite-sulfide composite nanomaterials.

3. The method for preparing selenite-sulfide composite nanomaterials according to claim 1 or 2, characterized in that: In the selenite-sulfide composite nanomaterial, the selenite layer is located between the sulfide layer and the current collector, and there is a strong interfacial interaction between the selenite and the transition metal sulfide.

4. The method for preparing selenite-sulfide composite nanomaterials according to claim 1 or 2, characterized in that: The selenite-sulfide composite nanomaterial is transformed in situ into a transition metal hydroxide during electrochemical processes, and provides capacity through a reversible reaction between the hydroxide and the hydroxyl oxide.

5. The application of selenite-sulfide composite nanomaterials as electrode materials for supercapacitors, characterized by: The selenite-sulfide composite nanomaterial was prepared using the preparation method described in any one of claims 1-4.

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