Preparation method and application of two-dimensional ultrathin ZnIn2S4 nanosheet material with adjustable indium vacancy

Abstract

The invention discloses a preparation method and application of a two-dimensional ultrathin ZnIn2S4 nanosheet material with adjustable indium vacancy, and belongs to the technical field of sodium ion battery materials. The preparation method comprises the following steps: (1) adding a zinc source, an indium source and a sulfur source into deionized water, and uniformly stirring to form a reaction mixture; (2) transferring the mixed solution into a lining of a polytetrafluoroethylene reaction kettle, and controlling the concentration of indium vacancy by regulating and controlling the hydrothermal reaction temperature; and (3) finally, centrifuging, washing and drying the obtained mixed substance to obtain the two-dimensional ultrathin ZnIn2S4 nanosheet material with the adjustable indium vacancy. The sodium-ion battery negative electrode material has the advantages of excellent rapid charging capability, high specific capacity, excellent rate capability and excellent cycling stability.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery anode material technology, specifically to the preparation method and application of two-dimensional ultrathin ZnIn2S4 nanosheets with tunable indium vacancies. Background Technology

[0002] Lithium-ion batteries (LIBs) are widely used in portable devices and electric vehicles, but their application in grid energy storage systems is limited by the scarcity, uneven distribution, and high cost of lithium resources. Sodium-ion batteries (SIBs) have attracted much attention due to their abundant sodium resources and similar electrochemical characteristics to lithium-ion batteries, making them particularly suitable for large-scale energy storage. However, the low energy density and poor cycle stability of sodium-ion batteries limit their widespread application. Therefore, developing high-performance electrode materials is crucial for improving the energy density and electrochemical performance of sodium-ion batteries.

[0003] Transition metal sulfides (TMSs) have become a highly promising class of materials for electrochemical energy storage due to their extremely high theoretical capacity and unique multi-step electron transfer mechanism. ZnIn2S4 (ZIS), with its sheet-like structure and tunable band alignment in a two-dimensional (2D) bimetallic semiconductor structure, has wide applications in energy conversion and storage. However, its practical application still faces several bottlenecks, including low conductivity, slow sodium ion kinetics, and significant volume expansion during electrochemical cycling, resulting in poor cycling performance and rate capability.

[0004] To address these issues, traditional modification methods focus on controlling the morphology and microstructure of the external interface to enhance the structural stability of the electrode material surface and promote diffusion kinetics. However, these methods have not effectively improved the ion / electron transport rate within the crystal structure, which limits the sodium ion storage performance of these materials. Therefore, there is an urgent need to explore new internal modulation methods to enhance the ion / electron transport properties within the crystal lattice structure.

[0005] Vacancy engineering is an effective strategy for modulating the electronic structure of electrode materials and improving their electrochemical performance. The introduction of vacancies can significantly increase electronic conductivity, while lowering the activation energy for ion migration, providing more active sites, increasing sodium ion adsorption and storage sites, and improving the specific capacity, cycle stability, and rate performance of the material (Se-Rich Functionalized FeS). xHollow Nanospheres for Accelerated and Long-Lasting Sodium Storage, Advanced Functional Materials. 2024, 35, 2414246. Therefore, regulating the vacancy structure at the atomic level is crucial for advancing the development of transition metal sulfide-based sodium-ion anode materials. Summary of the Invention

[0006] To address the aforementioned problems, this invention prepares a two-dimensional ultrathin ZnIn2S4 nanosheet material with tunable indium vacancies (ultra-V). In -ZIS-x), and applied it to sodium ion point cell anode materials.

[0007] ultra-V In -ZIS-x nanosheets possess an ultrathin nanosheet structure. This material exhibits the following characteristics: (1) the two-dimensional ultrathin nanosheet structure increases the electrolyte contact area, shortening the transport path of sodium ions and electrons; (2) indium vacancies enhance the material's electronic conductivity, increasing the adsorption and storage sites for sodium ions, thus improving the material's sodium storage capacity. Therefore, ultra-V In -ZIS-x, as a negative electrode material for sodium-ion batteries, exhibits excellent electrochemical performance.

[0008] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0009] This invention provides a method for preparing two-dimensional ultrathin ZnIn2S4 nanosheets with tunable indium vacancies, characterized by comprising the following steps: 1) Disperse the zinc source, indium source, and sulfur source in deionized water by stirring to form a reaction mixture solution; 2) The above reaction mixture was transferred to the inner lining of a polytetrafluoroethylene reactor for hydrothermal reaction. The mixture was centrifuged, washed and dried to obtain two-dimensional ultrathin ZnIn2S4 nanosheet material with adjustable indium vacancies.

[0010] Preferably, in step 1), the zinc source includes one or more of zinc chloride, zinc acetate, zinc nitrate hexahydrate, and zinc acetate dihydrate.

[0011] Preferably, in step 1), the indium source is one or more of indium chloride, indium chloride tetrahydrate, indium chloride hydrate, and indium nitrate hydrate.

[0012] Preferably, in step 1), the sulfur source is one or more of thiourea, sulfur powder, thioacetamide, and L-cysteine.

[0013] Preferably, in step 1), the molar ratio of zinc source, indium source and sulfur source is 1:2:8.

[0014] Preferably, in step 1), the stirring and dispersion time is 30~180 min, the hydrothermal reaction temperature is 120~180℃, and the reaction time is 12~24 h.

[0015] Preferably, in step 2), the detergent used for washing is ethanol and deionized water; the drying temperature is 50~80℃, and the drying time is 8~24h.

[0016] The present invention also provides a two-dimensional ultrathin ZnIn2S4 nanosheet material with adjustable indium vacancies, which is prepared by the above-described preparation method.

[0017] This invention also provides an application of a two-dimensional ultrathin ZnIn2S4 nanosheet material with adjustable indium vacancies as a negative electrode material for sodium-ion batteries.

[0018] Preferably, the application includes the following steps: mixing the tunable indium vacancy two-dimensional ultrathin ZnIn2S4 nanosheet material, acetylene black and polyvinylidene fluoride to form a slurry, and coating it on copper foil to obtain a sodium-ion battery negative electrode sheet.

[0019] Preferably, the application is carried out under the following conditions: current density 0.5~10 A g. 1 .

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1) The present invention provides a two-dimensional ultrathin ZnIn2S4 nanosheet material with adjustable indium vacancies. Its ultrathin nanosheet structure can effectively alleviate volume expansion, improve pseudocapacitance effect, significantly increase contact area with electrolyte and shorten ion / electron diffusion path. In Example 1 of the present invention, a two-dimensional ultrathin ZIS nanosheet material with cation indium vacancies was successfully synthesized by controlling hydrothermal temperature, with a thickness of 2.7 nm.

[0021] 2) This invention effectively controls the concentration of indium vacancies by controlling the temperature of the hydrothermal reaction. The controllable formation of indium vacancies within the two-dimensional nanosheets significantly shortens the transport path of sodium ions and electrons, providing a large number of active sites for enhanced electronic conductivity. The optimized two-dimensional ultrathin ZnIn2S4 nanosheet material with tunable indium vacancies generates a large number of active sites, reduces the diffusion barrier, and enhances the Na+ conductivity. + It enhances adsorption capacity and significantly improves conductivity and sodium storage capacity.

[0022] 3) The optimized Ultra-V of this invention In-ZIS-2 exhibits excellent electrochemical performance as a negative electrode material for sodium-ion batteries: at a current density of 0.5 A g 1 After 100 cycles, it can maintain 687.5 mAh·g. 1 The capacity; at a current density of 10 A·g 1 After 800 cycles, it can maintain 522.9 mAh·g. 1 The high capacity demonstrates that the material obtained in this invention possesses excellent resistance to high-current interference and sodium-ion transport capabilities, providing a valuable reference for the development of fast-charging and fast-discharging sodium-ion batteries. This invention elucidates the mechanism by which vacancies promote the rapid diffusion of electrons and sodium ions, achieving outstanding discharge performance and cycle stability. It provides valuable inspiration for the design of advanced sodium-ion battery materials.

[0023] 4) The preparation method used in this invention is simple, reliable, reproducible, low-cost, environmentally friendly, and has practical commercialization and large-scale production prospects. Attached Figure Description

[0024] Figure 1 The ultra-V obtained in Example 1 In SEM image of -ZIS-1.

[0025] Figure 2 Ultra-V was prepared in Example 2. In XRD patterns of ZIS-2 and ZIS.

[0026] Figure 3 Ultra-V was prepared for Example 2. In SEM image of -ZIS-2.

[0027] Figure 4 The SEM image of ZIS obtained in Example 2 is shown.

[0028] Figure 5 Ultra-V was prepared in Example 2. In AFM diagram of -ZIS-2.

[0029] Figure 6 Ultra-V was prepared in Example 2. In TEM image of ZIS-2.

[0030] Figure 7 Ultra-V was prepared in Examples 1, 2, and 3. In -ZIS-1, ultra-V In -ZIS-2, ZIS and ultra-VIn EPR diagram of -ZIS-3.

[0031] Figure 8 Ultra-V was prepared in Example 2. In -ZIS-2 electrode at 10 A g 1 Long-cycle performance at current density.

[0032] Figure 9 Ultra-V obtained in Example 3 In SEM image of -ZIS-3. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments.

[0034] Example 1 A method for preparing two-dimensional ultrathin ZnIn2S4 nanosheets with tunable indium vacancies includes the following steps: 1) Preparation of ZnIn2S4: 0.8 mmol Zn(CH3COO)2 2H₂O and 1.6 mmol InCl₃ 4H2O was dissolved in 60mL of deionized water and stirred for 30 min. Then 6.4 mmol of thioacetamide (TAA) was added and stirred for another 10 min to obtain the reaction mixture. 2) Pour the mixed solution into a sealed 100 mL polytetrafluoroethylene liner and hydrothermally react at 120 °C for 12 h. After naturally cooling to room temperature, collect the resulting yellow precipitate by centrifugation and wash several times with water and ethanol. Finally, obtain ZIS by centrifugation, washing, and drying. 3) Preparation of Ultra-V In -ZIS-1: First add 0.5 mmol Zn(NO3)2 6H2O, 1.0 mmol In(NO3)3 xH2O and 4.0 mmol L-cysteine ​​were dissolved in 60 mL of deionized water and stirred for 60 min to obtain a reaction mixture. 4) Transfer the mixture to a sealed 100 mL PTFE-lined container and heat at 140°C for 18 h. After naturally cooling to room temperature, centrifuge to separate the dark green product, then wash three times with deionized water and ethanol. Finally, after centrifugation, washing, and drying, obtain Ultra-V. In -ZIS-1.

[0035] 5) The ultra-V obtained by the above preparation method In-ZIS-1 is used for electrochemical performance testing of sodium-ion battery anode materials, including the following steps: a. Preparation of the working electrode: The active material ultra-V In ZIS-1, acetylene black, and polyvinylidene fluoride were dispersed in N-methyl-2-pyrrolidone solvent at a mass ratio of 8:1:1 and uniformly mixed to form a slurry. The slurry was then coated onto copper foil and dried in a vacuum oven at 80°C for 12 hours. b. Sodium-ion battery assembly: Assemble the 2016 button battery in an argon-filled glove box, using an active material coated electrode as the working electrode, a sodium sheet as the counter electrode, Whatman glass fiber as the separator, and 1.0M NaPF6 dissolved in diethylene glycol dimethyl ether as the electrolyte. c. Electrochemical performance testing: Conducted using a NEWARE CT-4008T-5 V 20 mA battery testing system, with a voltage range of 0.01 - 3.0 V. (ultra-V) In -ZIS-1 electrode at 10 A g -1 After 800 cycles at the specified current, the capacity was 390.9 mAh g. -1 Reversible capacity.

[0036] Figure 1 The ultra-V obtained in Example 1 In The SEM image of -ZIS-1 shows a spherical structure composed of nanosheets.

[0037] Example 2 A method for preparing two-dimensional ultrathin ZnIn2S4 nanosheets with tunable indium vacancies includes the following steps: 1) Preparation of ZnIn2S4: 0.8 mmol Zn(CH3COO)2 2H₂O and 1.6 mmol InCl₃ 4H2O was dissolved in 60mL of deionized water and stirred for 30 min. Then 6.4 mmol of thioacetamide (TAA) was added and stirred for another 10 min to obtain the reaction mixture. 2) Pour the mixed solution into a sealed 100 mL polytetrafluoroethylene-lined container and hydrothermally react at 120 °C for 12 h. After naturally cooling to room temperature, collect the resulting yellow precipitate by centrifugation and wash several times with water and ethanol. Finally, obtain ZIS by centrifugation, washing, and drying. 3) Preparation of Ultra-V In -ZIS-2: First add 0.5 mmol Zn(NO3)2 6H2O, 1.0 mmol In(NO3)3 xH2O and 4.0 mmol L-cysteine ​​were dissolved in 60 mL of deionized water and stirred for 60 min to obtain a reaction mixture. 4) Transfer the mixture to a sealed 100 mL PTFE-lined container and heat at 160°C for 18 h. After naturally cooling to room temperature, centrifuge to separate the dark green product, then wash three times with deionized water and ethanol. Finally, after centrifugation, washing, and drying, obtain Ultra-V. In -ZIS-2.

[0038] 5) The ultra-V obtained by the above preparation method In -ZIS-2 is used for electrochemical performance testing of sodium-ion battery anode materials, including the following steps: a. Preparation of the working electrode: The active material ultra-V In -ZIS-2 or ZIS, acetylene black and polyvinylidene fluoride are dispersed in N-methyl-2-pyrrolidone solvent at a mass ratio of 8:1:1 and mixed evenly to form a slurry. The slurry is then coated onto copper foil and dried in a vacuum oven at 80°C for 12 hours to obtain the negative electrode sheet for sodium-ion batteries. b. Sodium-ion battery assembly: Assemble the 2016 button battery in an argon-filled glove box, using an active material coated electrode as the working electrode, a sodium sheet as the counter electrode, Whatman glass fiber as the separator, and 1.0M NaPF6 dissolved in diethylene glycol dimethyl ether as the electrolyte. c. Electrochemical performance testing: The testing was conducted using a NEWARE CT-4008T-5 V 20 mA battery testing system, with a voltage range of 0.01 - 3.0 V. The ultra-VIn-ZIS-2 electrode was tested at a current density of 0.5 A g. 1 After 100 cycles, it can maintain 687.5 mAh·g. 1 The capacity; in 10 A g -1 After 800 cycles at a current of [current value missing], the electrode still maintains a high 522.9 mAh g⁻¹. -1 High reversible capacity. ZIS electrode at 10 A g -1 After 800 cycles at a given current, the capacity was reduced to only 275.6 mAh g. -1 Capacity. Ultra-V In The excellent electrochemical performance of the ZIS-2 electrode is mainly attributed to the introduction of appropriate indium cation vacancies to bind the ultrathin nanosheets and the formation of strong carbon-sulfur bonds in the bimetallic transition metal sulfide, which provides more active sites, shortens the ion / electron transport distance, enhances the stability of the electrode structure, and improves the reaction kinetics.

[0039] Figure 2 Ultra-V prepared in Example 2 In XRD patterns of ZIS-2 and ZIS, from which the Ultra-V can be seen. In Both ZIS-2 and ZIS materials exhibit similar diffraction peaks to the hexagonal phase of ZnIn2S4 (JCPDS No. 65-2023). This indicates that the crystal structure of the samples remains intact after the introduction of indium vacancies.

[0040] Figure 3 Ultra-V prepared in Example 2 In The SEM image of ZIS-2 shows that Ultra-V... In -ZIS-2 material is composed of ultrathin nanosheets.

[0041] Figure 4 The image shows a SEM image of ZIS prepared in Example 2. The ZnIn2S4 material has a nanoflower-like structure composed of nanosheets.

[0042] Figure 5 Ultra-V prepared in Example 2 In -ZIS-2 AFM diagram, from which you can see Ultra-V In -ZIS-2 material has ultrathin nanosheets with a thickness of about 2.7 nm.

[0043] Figure 6 Ultra-V was prepared in Example 2. In TEM image of ZIS-2, with interplanar spacings of 0.29 and 0.31 nm, corresponding to the (104) and (013) planes of ZIS, respectively.

[0044] Figure 8 Ultra-V was prepared in Example 2. In -ZIS-2 electrode at 10 A g 1. Long-cycle performance at current density, Ultra-V In -ZIS-2 electrode at 10 A g -1 After 800 cycles at a current of [current value missing], the electrode still maintains a high capacity of 522.9 mAh g. -1 High reversible capacity, Ultra-V In The -ZIS-2 electrode exhibits excellent electrochemical performance.

[0045] Example 3 A method for preparing two-dimensional ultrathin ZnIn2S4 nanosheets with tunable indium vacancies includes the following steps: 1) Preparation of ZnIn2S4: 0.8 mmol Zn(CH3COO)2 2H₂O and 1.6 mmol InCl₃ 4H2O was dissolved in 60mL of deionized water and stirred for 30 min. Then 6.4 mmol of thioacetamide (TAA) was added and stirred for another 10 min to obtain the reaction mixture. 2) Pour the mixed solution into a sealed 100 mL polytetrafluoroethylene-lined container and hydrothermally react at 120 °C for 12 hours. After naturally cooling to room temperature, collect the resulting yellow precipitate by centrifugation and wash several times with water and ethanol. Finally, obtain ZIS by centrifugation, washing, and drying. 3) Preparation of Ultra-V In -ZIS-3: First add 0.5 mmol Zn(NO3)2 6H2O, 1.0 mmol In(NO3)3 xH2O and 4.0 mmol L-cysteine ​​were dissolved in 60 mL of deionized water and stirred for 60 min to obtain a reaction mixture. 4) Transfer the mixture to a sealed 100 mL PTFE-lined container and heat at 180°C for 18 hours. After naturally cooling to room temperature, centrifuge to separate the dark green product, then wash three times with deionized water and ethanol. Finally, after centrifugation, washing, and drying, obtain Ultra-V. In -ZIS-3.

[0046] 5) V obtained by the above preparation method In -ZIS-3 is used for electrochemical performance testing of sodium-ion battery anode materials, including the following steps: a. Preparation of the working electrode: The active material ultra-V In ZIS-3, acetylene black, and polyvinylidene fluoride were dispersed in N-methyl-2-pyrrolidone solvent at a mass ratio of 8:1:1 and uniformly mixed to form a slurry. The slurry was then coated onto copper foil and dried in a vacuum oven at 80°C for 12 hours. b. Sodium-ion battery assembly: Assemble the 2016 button battery in an argon-filled glove box, using an active material coated electrode as the working electrode, a sodium sheet as the counter electrode, Whatman glass fiber as the separator, and 1.0M NaPF6 dissolved in diethylene glycol dimethyl ether as the electrolyte. c. Electrochemical performance testing: Conducted using a NEWARE CT-4008T-5 V 20 mA battery testing system, with a voltage range of 0.01 - 3.0 V. (ultra-V) In -ZIS-3 electrode at 10 A g -1After 800 cycles at the specified current, the capacity was 420.3 mAh g. -1 Reversible capacity.

[0047] Figure 7 Ultra-V was prepared in Examples 1, 2, and 3. In -ZIS-1, ZIS, ultra-V In -ZIS-2 and ultra-V In The EPR plot of -ZIS-3 and electron spin resonance (EPR) confirmed the presence of indium vacancies. The results also showed that the number of indium vacancies increased with increasing temperature during the hydrothermal reaction (where the g value was 2.005).

[0048] Figure 9 The ultra-V obtained in Example 3 In The SEM image of ZIS-3 shows a spherical structure composed of nanosheets.

[0049] In summary, compared with the prior art, the present invention has the following advantages and beneficial effects: 1) The present invention provides a two-dimensional ultrathin ZnIn2S4 nanosheet material with adjustable indium vacancies. Its ultrathin nanosheet structure can effectively alleviate volume expansion, improve pseudocapacitance effect, significantly increase contact area with electrolyte and shorten ion / electron diffusion path. The present invention successfully synthesized a two-dimensional ultrathin ZIS nanosheet material with cation indium vacancies with a thickness of 2.7 nm by controlling hydrothermal temperature.

[0050] 2) This invention effectively controls the concentration of indium vacancies by controlling the temperature of the hydrothermal reaction. The controllable formation of indium vacancies within the two-dimensional nanosheets significantly shortens the transport path of sodium ions and electrons, providing a large number of active sites for enhanced electronic conductivity. The optimized ultra-V in Example 1... In The -ZIS-2 structure generates a large number of active sites, lowers the diffusion barrier, and enhances Na+ diffusion. + It enhances adsorption capacity and significantly improves conductivity and sodium storage capacity.

[0051] 3) Ultra-V prepared in Example 1 of the present invention In ZIS-2 nanosheets exhibit excellent electrochemical performance as anode materials for sodium-ion batteries: at a current density of 0.5 A g... 1 After 100 cycles, it can maintain 687.5 mAh·g. 1 The capacity; at a current density of 10 A·g 1 After 800 cycles, it can maintain 522.9 mAh·g. 1 The high capacity demonstrates that the material obtained in this invention possesses excellent resistance to high-current interference and sodium-ion transport capabilities, providing a valuable reference for the development of fast-charging and fast-discharging sodium-ion batteries. This invention elucidates the mechanism by which vacancies promote the rapid diffusion of electrons and sodium ions, achieving outstanding discharge performance and cycle stability. It provides valuable inspiration for the design of advanced sodium-ion battery materials.

[0052] 4) The preparation method used in this invention is simple, reliable, reproducible, low-cost, environmentally friendly, and has practical commercialization and large-scale production prospects.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any changes, substitutions, modifications, etc., made by those skilled in the art without departing from the spirit and essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing two-dimensional ultrathin ZnIn2S4 nanosheets with tunable indium vacancies, characterized in that, Includes the following steps: 1) Disperse the zinc source, indium source, and sulfur source in deionized water by stirring to form a reaction mixture solution; 2) The above reaction mixture was transferred to the inner lining of a polytetrafluoroethylene reactor for hydrothermal reaction to obtain a mixture. After centrifugation, washing and drying, a two-dimensional ultrathin ZnIn2S4 nanosheet material with adjustable indium vacancies was obtained.

2. The preparation method according to claim 1, characterized in that, In step 1), the zinc source includes one or more of zinc chloride, zinc acetate, zinc nitrate hexahydrate, and zinc acetate dihydrate.

3. The preparation method according to claim 1, characterized in that, In step 1), the indium source is one or more of indium chloride, indium chloride tetrahydrate, indium chloride hydrate, and indium nitrate hydrate.

4. The preparation method according to claim 1, characterized in that, In step 1), the sulfur source is one or more of thiourea, sulfur powder, thioacetamide, and L-cysteine.

5. The preparation method according to claim 1, characterized in that, In step 1), the molar ratio of the zinc source, indium source, and sulfur source is 1:2:

8.

6. The preparation method according to claim 1, characterized in that, In step 2), the stirring and dispersion time is 30-180 min; the hydrothermal reaction temperature is 120-180℃ and the reaction time is 12-24 h; the washing agent used is ethanol and deionized water; the drying temperature is 50-80℃ and the drying time is 8-24 h.

7. A two-dimensional ultrathin ZnIn2S4 nanosheet material with tunable indium vacancies prepared by the preparation method according to any one of claims 1-6, characterized in that, The indium vacancy concentration is adjustable; by controlling the temperature of the hydrothermal reaction, the concentration of indium vacancy can be effectively controlled.

8. The application of the two-dimensional ultrathin ZnIn2S4 nanosheet material with adjustable indium vacancies as described in claim 7 as a negative electrode material for sodium-ion batteries.

9. The application of the two-dimensional ultrathin ZnIn2S4 nanosheet material with tunable indium vacancies as a negative electrode material for sodium-ion batteries according to claim 8, characterized in that, The application includes the following steps: mixing the tunable indium vacancy two-dimensional ultrathin ZnIn2S4 nanosheet material, acetylene black and polyvinylidene fluoride to form a slurry, and coating it on copper foil to obtain a sodium-ion battery negative electrode sheet.

10. The application of the two-dimensional ultrathin ZnIn2S4 nanosheet material with tunable indium vacancies according to claim 9, characterized in that, The application was carried out under the following conditions: current density 0.5~10 A g. 1 .

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