Yolk double-shell structure zinc thiophosphate material as well as preparation method and application thereof
By preparing a zinc thiophosphate material with a yolk-like double-shell structure, the conductivity and cycle stability problems of sodium-ion battery anode materials were solved, achieving efficient electron/ion conduction and volume stability, thus improving battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANCHANG UNIV
- Filing Date
- 2026-02-24
- Publication Date
- 2026-05-15
AI Technical Summary
Existing sodium-ion battery anode materials, such as hard carbon, have poor rate performance and limited specific capacity, while traditional transition metal thiophosphate materials have poor conductivity and insufficient cycle stability.
Zinc thiophosphate material with a yolk double-shell structure was prepared by template etching. Through ZIF-8 precursor coating, template etching, and simultaneous carbonization and sulfidation treatment, ZnPS3/NC@C material was formed, which combined a dual conductive network of MOF-derived nitrogen-doped carbon and phenolic resin-derived carbon shell.
It improves the conductivity and cycling stability of the material, exhibiting high first-cycle coulombic efficiency and long cycle life, mitigating volume expansion during sodiumization/desodiumization, and enhancing electron/ion conduction.
Smart Images
Figure CN122035930A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sodium-ion battery technology, and in particular to a yolk-double-shell structured zinc thiophosphate material, its preparation method, and its application. Background Technology
[0002] The ongoing global energy transition has spurred in-depth research into novel energy storage systems such as sodium-ion batteries, aiming to achieve high energy density, long cycle life, and good environmental compatibility. While hard carbon has been widely used as an anode material in sodium-ion batteries, its development is hampered by issues such as poor rate performance and limited specific capacity (~300 mAh g⁻¹). Therefore, developing novel anode materials that combine high performance with feasible manufacturing processes has become a key research direction.
[0003] Transition metal thiophosphates (TMPs), as a novel class of two-dimensional layered materials, have attracted considerable attention due to their potential in electrochemical energy storage. Their unique P2S6 octahedral units are bridged by transition metal ions (M2+), forming an abc stacked layered arrangement. The approximately 6.5 Å van der Waals gaps between the layers not only provide channels for the rapid insertion / extraction of sodium ions but also effectively buffer volume changes during cycling, thereby improving structural stability. While TMPs offer advantages over hard carbon materials, traditional TMPs still suffer from poor conductivity and insufficient cycle stability when used as anode materials in sodium-ion batteries, and their performance requires further improvement. Summary of the Invention
[0004] The purpose of this invention is to provide a zinc thiophosphate material with a yolk double-shell structure, its preparation method and application, in order to solve the problems existing in the prior art.
[0005] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of the present invention: a method for preparing a zinc thiophosphate material with a yolk double-shell structure, comprising the following steps: 2-methylimidazole, zinc source and solvent 1 were mixed and heated to obtain ZIF-8 precursor (solid polyhedral structure, used as template); The ZIF-8 precursor was dispersed in a mixed solvent, and CTAB, resorcinol and ammonia were added. The mixture was stirred and reacted, and then formaldehyde was added. The reaction was continued to be stirred to obtain a ZIF-8@RF (RF represents phenolic resin formed by the polymerization of resorcinol and formaldehyde) precursor (i.e., ZIF-8 with a phenolic resin shell. In this step, resorcinol and formaldehyde form a shell on the surface of ZIF-8 through a polymerization reaction, resulting in a solid polyhedron with a core (ZIF-8) shell (RF) structure). The ZIF-8@RF precursor was mixed with solvent 2 and tannic acid (TA, as an acidic etchant), and etched by stirring to obtain a yolk-double-shell structure ZIF-8 / TA-Zn@RF. (In this step, TA (acidic etchant) molecules penetrated the RF shell and interacted with the Zn on the ZIF-8 surface.) 2+ Strong ion coordination forms an insoluble TA-Zn composite shell. Although this shell partially shields the internal ZIF-8 from direct contact with the external TA, TA molecules and H... + Ions can still diffuse slowly inward through defects or pores in the shell. Due to the shell's restriction on mass transport, the outward diffusion rate of ligands significantly exceeds that of TA and Zn. 2+ The inward diffusion rate leads to a net mass loss inside and the formation of a cavity—a clear manifestation of the Kirkendall effect. Ultimately, due to the constraints of the double-shell structure, the internal ZIF-8 is not completely etched, forming an inner yolk shell structure composed of the TA-Zn complex and residual ZIF-8, which is then encased by the RF outer shell layer, thus forming a yolk double-shell structure. The egg yolk bishell structure ZIF-8 / TA-Zn@RF was subjected to simultaneous carbonization and sulfurization treatment under a sulfur-containing atmosphere to obtain the egg yolk bishell structure ZnS / NC@C. (After simultaneous carbonization and sulfurization treatment, the RF outer shell layer of the egg yolk bishell precursor ZIF-8 / TA-Zn@RF is carbonized to form a carbon (C) layer, and the Zn in the internal ZIF-8 / TA-Zn is...) 2+ The material is converted to ZnS by sulfidation, while TA and ZIF-8 organic matter are carbonized to generate nitrogen-doped carbon (NC), which together form the internal yolk shell unit ZnS / NC. The material as a whole maintains the yolk double-shell configuration completely during the phase transition, and is ultimately successfully transformed into a ZnS / NC@C composite material. The egg yolk double-shell structure ZnS / NC@C is subjected to phosphorus sulfide treatment under a phosphorus-sulfur atmosphere to obtain the egg yolk double-shell structure ZnPS3 / NC@C, which is the egg yolk double-shell structure zinc thiophosphate material (in this step, the ZnS in the inner egg yolk shell ZnS / NC in ZnS / NC@C is converted into ZnPS3, and the overall egg yolk double-shell structure remains unchanged).
[0006] To overcome the problems of poor conductivity and insufficient cycle stability of traditional transition metal thiophosphate materials, this invention proposes a strategy for preparing a yolk-shell structured zinc thiophosphate material based on a template etching method, and applies it to the anode of high-performance sodium-ion batteries. Specifically, this invention first prepares a ZIF-8 precursor (a metal-organic framework, i.e., MOF material) template through a solvothermal reaction of a zinc source and 2-methylimidazole. Subsequently, it undergoes sequential coating, template etching, simultaneous carbonization and sulfidation treatments, and phosphoric sulfidation treatment, ultimately obtaining a ZnPS3 / NC@C material with an excellent electrochemical performance and a yolk-shell structure. Using MOF as a template, the porous nature of MOF and its derived carbon skeleton help enhance electron / ion conduction and alleviate volume expansion during sodiumization / desodiumization. The unique hollow and eggshell structure shortens the ion migration path, effectively adapts to changes in material volume, and improves the material's cycle and rate performance. Therefore, this invention combines a dual conductive network of nitrogen-doped carbon derived from MOF and carbon shell derived from phenolic resin, which significantly improves the overall conductivity of the material, thereby giving the battery higher first-cycle coulombic efficiency and better long-cycle stability.
[0007] Compared with traditional transition metal thiophosphate preparation processes, the method of this invention is safer and allows for precise control of the yolk-double-shell morphology of the metal phosphorus sulfide. The resulting yolk-double-shell structured zinc thiophosphate material exhibits hollow porous characteristics, high specific surface area, and structural stability compared to pure zinc thiophosphate prepared by traditional processes. When used as a negative electrode material in sodium-ion batteries, it demonstrates higher initial charge-discharge efficiency and excellent cycle stability.
[0008] Furthermore, the zinc source includes zinc nitrate, zinc acetate, zinc chloride, or zinc sulfate.
[0009] Furthermore, the solvent 1 includes anhydrous methanol.
[0010] Furthermore, the molar ratio of the 2-methylimidazole to the zinc source is 3-8:1.
[0011] Furthermore, the heating reaction is carried out at a temperature of 40-80°C for 4-12 hours.
[0012] Further, the mixing of 2-methylimidazole, zinc source and solvent 1 includes: dissolving 2-methylimidazole and zinc source in solvent 1 respectively to prepare 2-methylimidazole solution and zinc source solution, and then pouring the 2-methylimidazole solution into the zinc source solution under rapid stirring.
[0013] Furthermore, the concentration of the 2-methylimidazole solution is 2-6M, and the concentration of the zinc source solution is 0.3-0.7M.
[0014] Furthermore, the mixed solvent is a mixture of anhydrous methanol and water.
[0015] Furthermore, the ratio of the ZIF-8 precursor, CTAB, resorcinol, ammonia, and formaldehyde is 1g:2-3g:0.4-1.6g:1-3mL:0.5-3mL.
[0016] Furthermore, after adding CTAB, resorcinol, and ammonia, the reaction is stirred for 20-40 minutes.
[0017] Furthermore, after adding formaldehyde, the reaction should continue to be stirred for 6-12 hours.
[0018] Furthermore, the solvent 2 includes anhydrous methanol.
[0019] Furthermore, the mass ratio of the ZIF-8@RF precursor to the tannic acid is 0.6:0.8-1.2.
[0020] Furthermore, the stirring etching time is 30-120 minutes.
[0021] Furthermore, the steps of simultaneously carbonizing and sulfiding the egg yolk double-shell structure ZIF-8 / TA-Zn@RF under a sulfur-containing atmosphere include: placing the egg yolk double-shell structure ZIF-8 / TA-Zn@RF downstream of a tube furnace, placing sulfur powder upstream of the tube furnace, introducing inert gas, and then heating to 350-450℃ for simultaneous carbonization and sulfidation (inert gas is introduced first, then heating begins).
[0022] Further, the step of phosphorus sulfidation treatment of the egg yolk double-shell structure ZnS / NC@C under a phosphorus-sulfur atmosphere includes: placing the egg yolk double-shell structure ZnS / NC@C in the downstream temperature zone of a dual-temperature zone tube furnace, placing the phosphorus-sulfur powder in the upstream temperature zone of the dual-temperature zone tube furnace, setting the upstream temperature zone temperature to 280-330℃ and the downstream temperature zone temperature to 450-600℃, introducing inert gas, and then simultaneously starting to heat up the upstream and downstream temperature zones, and holding the temperature after heating to the set temperature for phosphorus sulfidation treatment.
[0023] Furthermore, the mass ratio of the egg yolk double-shell structure ZIF-8 / TA-Zn@RF to the sulfur powder is 0.5:2-4.
[0024] Furthermore, the mass ratio of phosphorus to sulfur in the sulfur-phosphorus powder is 1-2:1-3.
[0025] Furthermore, the simultaneous carbonization and sulfidation treatment takes 2-4 hours (i.e., holding at 350-450℃ for 2-4 hours).
[0026] Furthermore, during the simultaneous carbonization and sulfidation process, the flow rate of the inert gas is 30-60 mL / min.
[0027] Furthermore, the simultaneous carbonization and sulfidation treatment at 350-450℃ includes a heating rate of 3-8℃ / min.
[0028] Furthermore, the mass ratio of the egg yolk double-shell structure ZnS / NC@C to the sulfur-phosphorus powder is 0.1:1-2.
[0029] Furthermore, the phosphorus sulfidation treatment takes 1-4 hours.
[0030] Furthermore, during the phosphorus sulfidation process, the flow rate of the inert gas is 30-60 mL / min.
[0031] Furthermore, simultaneously raising the temperature of the upstream and downstream temperature zones includes controlling the heating rate of the upstream and downstream temperature zones so that both zones reach the set temperature at the same time.
[0032] Furthermore, the heating rate in the upstream temperature zone is 14-19℃ / min, and the heating rate in the downstream temperature zone is 8-10℃ / min.
[0033] The second technical solution of the present invention: a zinc thiophosphate material with a yolk double-shell structure prepared by the above-described method.
[0034] Furthermore, the zinc thiophosphate material with the yolk double-shell structure has ZnPS3 as the core, ZnPS3 / NC as the inner yolk shell layer, and C as the outer shell layer, and has hollow and porous characteristics.
[0035] The third technical solution of the present invention: the application of the above-mentioned egg yolk double-shell structure zinc thiophosphate material in the preparation of sodium-ion battery anode.
[0036] The fourth technical solution of the present invention: a sodium-ion battery negative electrode, the raw material of which includes the above-mentioned egg yolk double-shell structure zinc thiophosphate material.
[0037] The present invention discloses the following technical effects: The yolk-double-shell ZnPS3 / NC@C structure prepared in this invention exhibits a larger specific surface area compared to pure-phase materials synthesized by traditional chemical vapor transport methods due to its unique hollow and porous characteristics. This not only provides abundant sodium-ion reactive sites but also effectively buffers volume expansion during charge and discharge, thus demonstrating excellent structural stability. When used as a zinc thiophosphate / carbon composite material as the anode in sodium-ion batteries, this material exhibits not only high initial coulombic efficiency but also long cycle life at high current densities. Attached Figure Description
[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0039] Figure 1 The images are TEM images of the intermediate products obtained in steps (1)-(4) of Example 1, where (a) is the ZIF-8 precursor, (b) is the ZIF-8@RF precursor, (c) is the structure ZIF-8 / TA-Zn@RF, and (d) is ZnS / NC@C.
[0040] Figure 2 The image shows a TEM image of the egg yolk bishell structure ZnPS3 / NC@C prepared in Example 1.
[0041] Figure 3 The image shows the XRD pattern of the egg yolk bishell structure ZnPS3 / NC@C prepared in Example 1.
[0042] Figure 4 The graph shows the cycle performance of a sodium-ion battery assembled using the egg yolk double-shell structure ZnPS3 / NC@C prepared in Example 1. Detailed Implementation
[0043] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0044] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0045] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0046] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0047] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0048] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.
[0049] Unless otherwise specified, room temperature or ambient temperature mentioned in the following embodiments, comparative examples and test examples of this invention refers to 20-30℃.
[0050] All raw materials used in the following embodiments, comparative examples and test examples of this invention are common commercial products, and the concentration of ammonia water is 25.0%.
[0051] Example 1 A zinc thiophosphate material with a yolk-like double-shell structure is prepared by the following steps: (1) Accurately weigh 640 mmol of 2-methylimidazole and 80 mmol of zinc nitrate, and dissolve them separately in 160 mL of anhydrous methanol to prepare 2-methylimidazole solution and zinc nitrate solution. Under rapid stirring, pour the 2-methylimidazole solution into the zinc nitrate solution, mix well, and place in a 60 °C oven to react for 10 hours. A white suspension was observed to form. After the reaction was completed, filter, wash with anhydrous methanol and dry to obtain white ZIF-8 precursor powder.
[0052] (2) Take 0.8g of the above ZIF-8 precursor powder and disperse it in a mixed solvent consisting of 480mL of anhydrous methanol and 110mL of water. After ultrasonic dispersion, add 1.84g of CTAB, 0.64g of resorcinol and 1.6mL of ammonia water in sequence, and stir at room temperature for 30 minutes. Then add 0.96mL of formaldehyde and continue stirring at room temperature for 12 hours until the solution gradually turns pink. After filtration, obtain the pink ZIF-8@RF precursor.
[0053] (3) Weigh 0.6 g of the obtained pink ZIF-8@RF precursor and add it to 40 mL of anhydrous methanol. Then add 1 g of tannic acid and stir and etch at room temperature for 30 minutes. After the reaction is complete, filter and dry to obtain brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material.
[0054] (4) Place 0.5g of the above-mentioned brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material and 3g of sulfur powder together in a tube furnace (single-temperature zone tube furnace), with the sulfur powder placed upstream and the egg yolk double-shell structure ZIF-8 / TA-Zn@RF material placed downstream. Introduce nitrogen gas (flow rate of 40mL / min) as carrier gas and protective gas, then raise the temperature to 400℃ at a rate of 5℃ / min and hold for 3 hours for simultaneous carbonization and sulfurization treatment. After the holding period, allow it to cool naturally to room temperature while maintaining the nitrogen gas supply to obtain dry black egg yolk double-shell structure ZnS / NC@C powder.
[0055] (5) Finally, 0.1g of black egg yolk double-shell structure ZnS / NC@C powder was weighed and placed in the downstream temperature zone of a dual-temperature zone tube furnace (set temperature 480℃, heating rate 15℃ / min), and 1g of phosphorus-sulfur powder mixed at a phosphorus to sulfur mass ratio of 1:2 was placed in the upstream temperature zone (set temperature 330℃, heating rate 10℃ / min). Nitrogen gas (flow rate 40mL / min) was introduced as the carrier gas and protective gas, and then the upstream and downstream temperature zones were heated simultaneously (initial temperature 30℃). After both the upstream and downstream temperature zones reached the set temperature (both reached the set temperature simultaneously), the temperature was maintained for 2 hours for phosphorus sulfidation reaction. After the temperature maintenance, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply, and finally a black solid powder was obtained, which is the egg yolk double-shell structure zinc thiophosphate material (abbreviated as egg yolk double-shell structure ZnPS3 / NC@C).
[0056] Figure 1 These are TEM images of the intermediate products obtained in steps (1)-(4) of this embodiment. Figure 2 This is a TEM image of the final yolk bishell structure ZnPS3 / NC@C prepared in this embodiment. Figure 1 and Figure 2 The morphological evolution of the products at each step of the synthesis of the egg yolk bishell structure ZnPS3 / NC@C is shown. Figure 1 In the diagram, (a) is the ZIF-8 precursor, (b) is the ZIF-8@RF precursor, (c) is the ZIF-8 / TA-Zn@RF structure, and (d) is the ZnS / NC@C. Figure 1 As shown in (a), the ZIF-8 precursor exhibits a solid polyhedral structure. Figure 1 Figure (b) shows that a solid polyhedron with a core (ZIF-8) shell (RF) structure was successfully obtained by uniformly coating the surface of ZIF-8 with a layer of phenolic resin (i.e., RF). Figure 1As shown in (c), under restrictive etching conditions, the internal ZIF-8 was not completely removed, but rather encapsulated within the RF shell along with the TA-Zn complex (formed from the etched portion of ZIF-8), forming an inner yolk shell (ZIF-8 / TA-Zn) - outer shell (RF) structure. Ultimately, as... Figure 1 As shown in (d), the yolk-double-shell precursor ZIF-8 / TA-Zn@RF, after undergoing simultaneous carbonization and sulfidation treatment, still maintains its yolk-double-shell configuration, successfully transforming into a yolk-double-shell structure ZnS / NC@C material. Figure 2 As can be seen, the final ZnPS3 / NC@C bishell material exhibits a typical yolk bishell polyhedral configuration with an overall size of approximately 1 μm. Its structure originates from the evolution of the ZnS / NC@C yolk bishell precursor, specifically: ZnPS3 / NC forms the inner yolk shell, and RF-derived C forms the outer shell, with the overall structure exhibiting obvious hollow and porous characteristics. In other words, the ZnPS3 / NC@C bishell structure presents a hollow polyhedral bishell structure with ZnPS3 / NC as the inner shell (i.e., the inner yolk shell) and C as the outer shell.
[0057] Figure 3 The XRD pattern of the egg yolk bishell structure ZnPS3 / NC@C prepared in Example 1 shows that the diffraction peak positions correspond perfectly with the standard card PDF#01-083-0467, indicating that the target product has been successfully synthesized.
[0058] Example 2 A zinc thiophosphate material with a yolk-like double-shell structure is prepared by the following steps: (1) Accurately weigh 480 mmol of 2-methylimidazole and 60 mmol of zinc chloride, and dissolve them separately in 160 mL of anhydrous methanol to prepare 2-methylimidazole solution and zinc chloride solution. Under rapid stirring, pour the 2-methylimidazole solution into the zinc chloride solution, mix well, and place in an 80 °C oven to react for 6 hours. A white suspension was observed to form. After the reaction was completed, filter, wash with anhydrous methanol and dry to obtain white ZIF-8 precursor powder.
[0059] (2) Take 0.8g of the above ZIF-8 precursor powder and disperse it in a mixed solvent consisting of 480mL of anhydrous methanol and 110mL of water. After ultrasonic dispersion, add 1.84g of CTAB, 0.82g of resorcinol and 1.9mL of ammonia water in sequence, and stir at room temperature for 30 minutes. Then add 1.2mL of formaldehyde and continue stirring at room temperature for 8 hours until the solution gradually turns pink. After filtration, obtain the pink ZIF-8@RF precursor.
[0060] (3) Weigh 0.6 g of the obtained pink ZIF-8@RF precursor and add it to 40 mL of anhydrous methanol. Then add 1 g of tannic acid and stir and etch at room temperature for 60 minutes. After the reaction is complete, filter and dry to obtain brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material.
[0061] (4) Place 0.5g of the above-mentioned brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material and 3g of sulfur powder together in a tube furnace, with the sulfur powder placed upstream and the egg yolk double-shell structure ZIF-8 / TA-Zn@RF material placed downstream. Nitrogen gas (flow rate of 40mL / min) is introduced as a carrier gas and protective gas, and then the temperature is increased to 450℃ at a rate of 5℃ / min and held for 3 hours for simultaneous carbonization and sulfurization treatment. After the holding period, the material is naturally cooled to room temperature while maintaining the nitrogen gas supply to obtain dry black egg yolk double-shell structure ZnS / NC@C powder.
[0062] (5) Finally, 0.1g of black egg yolk double-shell structure ZnS / NC@C powder was weighed and placed in the downstream temperature zone of a dual-temperature zone tube furnace (set temperature 550℃, heating rate 17.3℃ / min), and 1.5g of phosphorus-sulfur powder mixed at a phosphorus to sulfur mass ratio of 1:3 was placed in the upstream temperature zone (set temperature 300℃, heating rate 9℃ / min). Nitrogen gas (flow rate 50mL / min) was introduced as the carrier gas and protective gas, and then the upstream and downstream temperature zones were heated simultaneously (initial temperature 30℃). After both the upstream and downstream temperature zones reached the set temperature, the phosphorus sulfidation reaction was carried out for 2 hours. After the holding time was completed, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply, and finally a black solid powder was obtained, which is the egg yolk double-shell structure zinc thiophosphate material (abbreviated as egg yolk double-shell structure ZnPS3 / NC@C).
[0063] Example 3 A zinc thiophosphate material with a yolk-like double-shell structure is prepared by the following steps: (1) Accurately weigh 320 mmol of 2-methylimidazole and 96 mmol of zinc chloride, and dissolve them separately in 160 mL of anhydrous methanol to prepare 2-methylimidazole solution and zinc chloride solution. Under rapid stirring, pour the 2-methylimidazole solution into the zinc chloride solution, mix well, and place in a 50 °C oven to react for 8 hours. A white suspension was observed to form. After the reaction was completed, filter, wash with anhydrous methanol and dry to obtain white ZIF-8 precursor powder.
[0064] (2) Take 0.8g of the above ZIF-8 precursor powder and disperse it in a mixed solvent consisting of 480mL of anhydrous methanol and 110mL of water. After ultrasonic dispersion, add 1.84g of CTAB, 0.51g of resorcinol and 1.3mL of ammonia water in sequence, and stir at room temperature for 30 minutes. Then add 0.89mL of formaldehyde and continue stirring at room temperature for 10 hours until the solution gradually turns pink. After filtration, obtain the pink ZIF-8@RF precursor.
[0065] (3) Weigh 0.6 g of the obtained pink ZIF-8@RF precursor and add it to 40 mL of anhydrous methanol. Then add 0.8 g of tannic acid and stir and etch at room temperature for 60 minutes. After the reaction is complete, filter and dry to obtain brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material.
[0066] (4) Place 0.5g of the above-mentioned brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material and 3g of sulfur powder together in a tube furnace, with the sulfur powder placed upstream and the egg yolk double-shell structure ZIF-8 / TA-Zn@RF material placed downstream. Nitrogen gas (flow rate of 30mL / min) is introduced as a carrier gas and protective gas, and then the temperature is increased to 380℃ at a rate of 5℃ / min and held for 4 hours for simultaneous carbonization and sulfurization treatment. After the holding period, the material is naturally cooled to room temperature while maintaining the nitrogen gas supply to obtain dry black egg yolk double-shell structure ZnS / NC@C powder.
[0067] (5) Finally, 0.1g of black egg yolk double-shell structure ZnS / NC@C powder was weighed and placed in the downstream temperature zone of a dual-temperature zone tube furnace (set temperature 600℃, heating rate 19℃ / min), and 2.0g of phosphorus-sulfur powder mixed in a phosphorus-sulfur mass ratio of 1:1 was placed in the upstream temperature zone (set temperature 280℃, heating rate 8.3℃ / min). Nitrogen gas (flow rate 60mL / min) was introduced as the carrier gas and protective gas, and then the upstream and downstream temperature zones were heated simultaneously (initial temperature 30℃). After both the upstream and downstream temperature zones reached the set temperature, the temperature was maintained for phosphosulfurization reaction for 1 hour. After the temperature maintenance, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply, and finally a black solid powder was obtained, which is the egg yolk double-shell structure zinc thiophosphate material (abbreviated as egg yolk double-shell structure ZnPS3 / NC@C).
[0068] Example 4 A zinc thiophosphate material with a yolk-like double-shell structure is prepared by the following steps: (1) Accurately weigh 960 mmol of 2-methylimidazole and 110 mmol of zinc acetate, and dissolve them separately in 160 mL of anhydrous methanol to prepare 2-methylimidazole solution and zinc acetate solution. Under rapid stirring, pour the 2-methylimidazole solution into the zinc acetate solution, mix well, and place in a 50 °C oven to react for 12 hours. A white suspension was observed to form. After the reaction was completed, filter, wash with anhydrous methanol and dry to obtain white ZIF-8 precursor powder.
[0069] (2) Take 0.8g of the above ZIF-8 precursor powder and disperse it in a mixed solvent consisting of 480mL of anhydrous methanol and 110mL of water. After ultrasonic dispersion, add 1.84g of CTAB, 1.26g of resorcinol and 2.0mL of ammonia water in sequence, and stir at room temperature for 30 minutes. Then add 1.68mL of formaldehyde and continue stirring at room temperature for 8 hours until the solution gradually turns pink. After filtration, obtain the pink ZIF-8@RF precursor.
[0070] (3) Weigh 0.6 g of the obtained pink ZIF-8@RF precursor and add it to 40 mL of anhydrous methanol. Then add 1.2 g of tannic acid and stir and etch at room temperature for 90 minutes. After the reaction is complete, filter and dry to obtain brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material.
[0071] (4) Place 0.5g of the above-mentioned brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material and 4g of sulfur powder together in a tube furnace, with the sulfur powder placed upstream and the egg yolk double-shell ZIF-8 / TA-Zn@RF structure material placed downstream. Nitrogen gas (flow rate of 30mL / min) is introduced as a carrier gas and protective gas, and then the temperature is increased to 380℃ at a rate of 5℃ / min and held for 3 hours for simultaneous carbonization and sulfurization treatment. After the holding period, the material is naturally cooled to room temperature while maintaining the nitrogen gas supply to obtain dry black egg yolk double-shell structure ZnS / NC@C powder.
[0072] (5) Finally, 0.1g of black egg yolk double-shell structure ZnS / NC@C powder was weighed and placed in the downstream temperature zone of a dual-temperature zone tube furnace (set temperature 580℃, heating rate 18.3℃ / min), and 1.5g of phosphorus-sulfur powder mixed in a phosphorus-sulfur mass ratio of 2:1 was placed in the upstream temperature zone (set temperature 300℃, heating rate 9℃ / min). Nitrogen gas (flow rate 40mL / min) was introduced as the carrier gas and protective gas, and then the upstream and downstream temperature zones were heated simultaneously (initial temperature 30℃). After both the upstream and downstream temperature zones reached the set temperature, the phosphorus sulfidation reaction was carried out for 1.5 hours. After the holding time was completed, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply. Finally, a black solid powder was obtained, which is the egg yolk double-shell structure zinc thiophosphate material (abbreviated as egg yolk double-shell structure ZnPS3 / NC@C).
[0073] Example 5 A zinc thiophosphate material with a yolk-like double-shell structure is prepared by the following steps: (1) Accurately weigh 800 mmol of 2-methylimidazole and 100 mmol of zinc nitrate, and dissolve them separately in 160 mL of anhydrous methanol to prepare 2-methylimidazole solution and zinc nitrate solution. Under rapid stirring, pour the 2-methylimidazole solution into the zinc nitrate solution, mix well, and place in an 80 °C oven to react for 12 hours. A white suspension was observed to form. After the reaction was completed, filter, wash with anhydrous methanol and dry to obtain white ZIF-8 precursor powder.
[0074] (2) Take 0.8g of the above ZIF-8 precursor powder and disperse it in a mixed solvent consisting of 480mL of anhydrous methanol and 110mL of water. After ultrasonic dispersion, add 1.84g of CTAB, 0.92g of resorcinol and 1.6mL of ammonia water in sequence, and stir at room temperature for 30 minutes. Then add 1.44mL of formaldehyde and continue stirring at room temperature for 6 hours until the solution gradually turns pink. After filtration, obtain the pink ZIF-8@RF precursor.
[0075] (3) Weigh 0.6 g of the obtained pink ZIF-8@RF precursor and add it to 40 mL of anhydrous methanol. Then add 1.1 g of tannic acid and stir and etch at room temperature for 80 minutes. After the reaction is complete, filter and dry to obtain brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material.
[0076] (4) 0.5g of the above-mentioned brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material and 2g of sulfur powder were placed together in a tube furnace, with the sulfur powder placed upstream and the egg yolk double-shell structure ZIF-8 / TA-Zn@RF material placed downstream. Nitrogen gas (flow rate of 50mL / min) was introduced as a carrier gas and protective gas, and then the temperature was increased to 420℃ at a rate of 5℃ / min and held for 2 hours for simultaneous carbonization and sulfurization. After the holding period, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply. After the reaction was completed, dry black egg yolk double-shell structure ZnS / NC@C powder was obtained.
[0077] (5) Finally, 0.1g of black egg yolk double-shell structure ZnS / NC@C powder was weighed and placed in the downstream temperature zone of a dual-temperature zone tube furnace (set temperature 490℃, heating rate 15.3℃ / min), and 1.5g of phosphorus-sulfur powder mixed at a phosphorus to sulfur mass ratio of 1:3 was placed in the upstream temperature zone (set temperature 280℃, heating rate 8.3℃ / min). Nitrogen gas (flow rate 30mL / min) was introduced as the carrier gas and protective gas, and then the upstream and downstream temperature zones were heated simultaneously (initial temperature 30℃). After both the upstream and downstream temperature zones reached the set temperature, the phosphorus sulfidation reaction was carried out for 2 hours. After the holding time was completed, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply. Finally, a black solid powder was obtained, which is the egg yolk double-shell structure zinc thiophosphate material (abbreviated as egg yolk double-shell structure ZnPS3 / NC@C).
[0078] Example 6 A zinc thiophosphate material with a yolk-like double-shell structure is prepared by the following steps: (1) Accurately weigh 320 mmol of 2-methylimidazole and 50 mmol of zinc nitrate, and dissolve them separately in 160 mL of anhydrous methanol to prepare 2-methylimidazole solution and zinc nitrate solution. Under rapid stirring, pour the 2-methylimidazole solution into the zinc nitrate solution, mix well, and place in a 50 °C oven to react for 10 hours. A white suspension was observed to form. After the reaction was completed, filter, wash with anhydrous methanol and dry to obtain white ZIF-8 precursor powder.
[0079] (2) Take 0.8g of the above ZIF-8 precursor powder and disperse it in a mixed solvent consisting of 480mL of anhydrous methanol and 110mL of water. After ultrasonic dispersion, add 1.84g of CTAB, 0.32g of resorcinol and 0.8mL of ammonia water in sequence, and stir at room temperature for 30 minutes. Then add 0.48mL of formaldehyde and continue stirring at room temperature for 10 hours until the solution gradually turns pink. After filtration, obtain the pink ZIF-8@RF precursor.
[0080] (3) Weigh 0.6 g of the obtained pink ZIF-8@RF precursor and add it to 40 mL of anhydrous methanol. Then add 1.2 g of tannic acid and stir and etch at room temperature for 60 minutes. After the reaction is complete, filter and dry to obtain brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material.
[0081] (4) 0.5g of the above-mentioned brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material and 4g of sulfur powder were placed together in a tube furnace, with the sulfur powder placed upstream and the egg yolk double-shell structure ZIF-8 / TA-Zn@RF material placed downstream. Nitrogen gas (flow rate of 60mL / min) was introduced as a carrier gas and protective gas, and then the temperature was increased to 450℃ at a rate of 5℃ / min and held for 2 hours for simultaneous carbonization and sulfurization. After the holding period, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply. After the reaction was completed, dry black egg yolk double-shell structure ZnS / NC@C powder was obtained.
[0082] (5) Finally, 0.1g of black egg yolk double-shell structure ZnS / NC@C powder was weighed and placed in the downstream temperature zone of a dual-temperature zone tube furnace (set temperature 450℃, heating rate 14℃ / min), and 1g of phosphorus-sulfur powder mixed at a phosphorus to sulfur mass ratio of 1:2 was placed in the upstream temperature zone (set temperature 330℃, heating rate 10℃ / min). Nitrogen gas (flow rate 40mL / min) was introduced as the carrier gas and protective gas, and then the upstream and downstream temperature zones were heated simultaneously (initial temperature 30℃). After both the upstream and downstream temperature zones reached the set temperature, the phosphorus sulfidation reaction was carried out for 3 hours. After the holding time was completed, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply. Finally, a black solid powder was obtained, which is the egg yolk double-shell structure zinc thiophosphate material (abbreviated as egg yolk double-shell structure ZnPS3 / NC@C).
[0083] Example 7 A zinc thiophosphate material with a yolk-like double-shell structure is prepared by the following steps: (1) Accurately weigh 640 mmol of 2-methylimidazole and 80 mmol of zinc nitrate, and dissolve them separately in 160 mL of anhydrous methanol to prepare 2-methylimidazole solution and zinc nitrate solution. Under rapid stirring, pour the 2-methylimidazole solution into the zinc nitrate solution, mix well, and place in a 60 °C oven to react for 10 hours. A white suspension was observed to form. After the reaction was completed, filter, wash with anhydrous methanol and dry to obtain white ZIF-8 precursor powder.
[0084] (2) Take 0.8g of the above ZIF-8 precursor powder and disperse it in a mixed solvent consisting of 480mL of anhydrous methanol and 110mL of water. After ultrasonic dispersion, add 1.84g of CTAB, 0.84g of resorcinol and 2.2mL of ammonia water in sequence, and stir at room temperature for 30 minutes. Then add 1.26mL of formaldehyde and continue stirring at room temperature for 12 hours until the solution gradually turns pink. After filtration, obtain the pink ZIF-8@RF precursor.
[0085] (3) Weigh 0.6 g of the obtained pink ZIF-8@RF precursor and add it to 40 mL of anhydrous methanol. Then add 1 g of tannic acid and stir and etch at room temperature for 120 minutes. After the reaction is complete, filter and dry to obtain brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material.
[0086] (4) 0.5g of the above-mentioned brown egg yolk double-shell structure ZIF-8 / TA-Zn@RF material and 3g of sulfur powder were placed together in a tube furnace, with the sulfur powder placed upstream and the egg yolk double-shell structure ZIF-8 / TA-Zn@RF material placed downstream. Nitrogen gas (flow rate of 30mL / min) was introduced as a carrier gas and protective gas, and then the temperature was increased to 400℃ at a rate of 5℃ / min and held for 4 hours for simultaneous carbonization and sulfurization. After the holding period, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply. After the reaction was completed, dry black egg yolk double-shell structure ZnS / NC@C powder was obtained.
[0087] (5) Finally, 0.1g of black egg yolk double-shell structure ZnS / NC@C powder was weighed and placed in the downstream temperature zone of a dual-temperature zone tube furnace (set temperature 480℃, heating rate 15℃ / min), and 1g of phosphorus-sulfur powder mixed at a phosphorus to sulfur mass ratio of 1:2 was placed in the upstream temperature zone (set temperature 330℃, heating rate 10℃ / min). Nitrogen gas (flow rate 50mL / min) was introduced as the carrier gas and protective gas, and then the upstream and downstream temperature zones were heated simultaneously (initial temperature 30℃). After both the upstream and downstream temperature zones reached the set temperature, the phosphorus sulfidation reaction was carried out for 2 hours. After the holding time was completed, the mixture was naturally cooled to room temperature while maintaining the nitrogen gas supply. Finally, a black solid powder was obtained, which is the egg yolk double-shell structure zinc thiophosphate material (abbreviated as egg yolk double-shell structure ZnPS3 / NC@C).
[0088] Comparative Example 1 A pure zinc thiophosphate (ZnPS3) material is prepared by the following steps: 0.1g of pure zinc sulfide powder was weighed and placed in the downstream zone of a dual-zone tube furnace (set temperature 480℃, heating rate 15℃ / min). 1g of phosphorus-sulfur powder mixed at a phosphorus to sulfur mass ratio of 1:2 was placed in the upstream zone (set temperature 330℃, heating rate 10℃ / min). Nitrogen gas (flow rate 40mL / min) was introduced as both carrier and protective gas. The upstream and downstream zones were then simultaneously heated (initial temperature 30℃). After both zones reached their set temperatures, the phosphorus sulfide reaction was carried out for 2 hours. After the holding period, the mixture was allowed to cool naturally to room temperature while maintaining nitrogen flow, ultimately yielding a grayish-white solid powder, which is the pure ZnPS3 material.
[0089] Comparative Example 2 A single-shell structured zinc thiophosphate material is prepared by the following steps: (1) Accurately weigh 640 mmol of 2-methylimidazole and 80 mmol of zinc nitrate, and dissolve them separately in 160 mL of anhydrous methanol to prepare 2-methylimidazole solution and zinc nitrate solution. Under rapid stirring, pour the 2-methylimidazole solution into the zinc nitrate solution, mix well, and place in a 60 °C oven to react for 10 hours. A white suspension was observed to form. After the reaction was completed, filter, wash with anhydrous methanol and dry to obtain white ZIF-8 precursor powder.
[0090] (2) Weigh 0.8g of the above white ZIF-8 precursor powder and add it to 40mL of anhydrous methanol. Then add 1g of tannic acid and stir and etch at room temperature for 30 minutes. After the reaction is complete, filter and dry to obtain eggshell structure (single-shell structure) ZIF-8 / TA-Zn material.
[0091] (3) Place 0.5g of the above-mentioned eggshell structure ZIF-8 / TA-Zn material and 3g of sulfur powder together in a tube furnace (single-temperature zone tube furnace), with the sulfur powder placed upstream and the eggshell structure ZIF-8 / TA-Zn material placed downstream. Introduce nitrogen gas (flow rate of 40mL / min) as carrier gas and protective gas, and heat to 400℃ at a rate of 5℃ / min, and hold for 3 hours for simultaneous carbonization and sulfurization treatment. After the holding period, allow it to cool naturally to room temperature while maintaining the nitrogen gas supply to obtain dry black eggshell structure ZnS / NC powder.
[0092] (4) Finally, weigh 0.1g of black eggshell-structured ZnS / NC powder and place it in the downstream temperature zone of a dual-temperature zone tube furnace (set temperature 480℃, heating rate 15℃ / min). Place 1g of phosphorus-sulfur powder mixed in a phosphorus-sulfur mass ratio of 1:2 in the upstream temperature zone (set temperature 330℃, heating rate 10℃ / min). Introduce nitrogen gas (flow rate 40mL / min) as carrier gas and protective gas, and then simultaneously start heating the upstream and downstream temperature zones (initial temperature 30℃). After both the upstream and downstream temperature zones reach the set temperature, maintain the temperature for 2 hours for phosphorus sulfidation reaction. After the holding time is completed, allow it to cool naturally to room temperature while maintaining the nitrogen gas supply. Finally, obtain black solid powder, which is eggshell-structured ZnPS3 / NC.
[0093] Test Example 1 Sodium-ion batteries were assembled using the egg yolk double-shell structure ZnPS3 / NC@C prepared in Examples 1-7, the pure ZnPS3 prepared in Comparative Example 1, or the eggshell structure ZnPS3 / NC material prepared in Comparative Example 2 as active negative electrode materials, and their electrochemical performance was tested.
[0094] The assembly and testing methods for sodium-ion batteries are as follows: To prepare a sodium-ion half-cell (CR2032 type) for electrochemical performance testing, the active negative electrode material, conductive agent Super P, and 4wt% polyvinylidene fluoride binder solution (solvent N-methylpyrrolidone) were weighed at a mass ratio of 7:2:25. The active negative electrode material and conductive agent were thoroughly mixed in a mortar for 15 minutes until the color was uniform. Then, the mixture was transferred to a small beaker, and the polyvinylidene fluoride binder solution was added dropwise under continuous stirring. Then, an appropriate amount of N-methylpyrrolidone solvent was added under magnetic stirring to form a homogeneous slurry with good flowability. The slurry was uniformly coated on the surface of copper foil and dried horizontally in a vacuum oven at 120℃ for 10 hours. The dried electrode sheet was punched to obtain a circular electrode with a diameter of 12mm, which is the negative electrode sheet. The active material loading was confirmed to be 1.2mg by weighing. Battery assembly was conducted in a glove box with strictly controlled moisture and oxygen content (H2O, O2 < 0.1 ppm): the negative electrode shell, negative electrode sheet (active negative electrode material side up), separator with 80 μL of electrolyte (1 M NaPF6 dissolved in 100% diethylene glycol dimethyl ether), sodium sheet, gasket, spring sheet, and positive electrode shell were stacked and assembled sequentially, followed by sealing under 6 MPa pressure. The encapsulated battery was then aged at room temperature for 12 hours to ensure sufficient electrolyte wetting. Finally, the aged battery was placed in the Blue Battery Testing System and tested at 2.0 A g within the voltage range of 0.01-3.0 V. -1 The system was subjected to constant current charge-discharge tests at a given current density to evaluate its electrochemical performance.
[0095] Test results are as follows Figure 4 As shown in Table 1. Figure 4The graph shows the cycle performance of a sodium-ion battery assembled using the egg yolk double-shell structure ZnPS3 / NC@C prepared in Example 1.
[0096] Table 1 As shown in Table 1, the egg yolk double-shell structure ZnPS3 / NC@C prepared in this invention exhibits high first-cycle coulombic efficiency and excellent long-cycle stability when used as a negative electrode active material for sodium-ion batteries. Specifically, the first-cycle coulombic efficiency of Examples 1-7 is not less than 65%; at 2A g -1 During high current density cycling tests, its cycle life can reach 676-2000 cycles, and it can still maintain ≥371mAh g after cycling. -1 The reversible capacity. Notably, the sample in Example 1 exhibited the best performance at 2A g. -1 After 2000 cycles at the current density, the capacity remained at 582 mAh g. -1 Meanwhile, its coulombic efficiency can reach 82%, demonstrating its excellent structural stability and electrochemical reversibility.
[0097] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A method for preparing a zinc thiophosphate material with a yolk-double-shell structure, characterized in that, Includes the following steps: 2-methylimidazole, zinc source and solvent 1 were mixed and heated to react, yielding the ZIF-8 precursor; The ZIF-8 precursor was dispersed in a mixed solvent, and CTAB, resorcinol and ammonia were added. The mixture was stirred and reacted, and then formaldehyde was added. The reaction was continued by stirring to obtain the ZIF-8@RF precursor. The ZIF-8@RF precursor was mixed with solvent 2 and tannic acid, stirred and etched to obtain the egg yolk double shell structure ZIF-8 / TA-Zn@RF; The egg yolk bishell structure ZIF-8 / TA-Zn@RF was subjected to simultaneous carbonization and sulfurization treatment in a sulfur-containing atmosphere to obtain the egg yolk bishell structure ZnS / NC@C. The egg yolk double-shell structure ZnS / NC@C was subjected to phosphorus sulfidation treatment under a phosphorus-sulfur atmosphere to obtain the egg yolk double-shell structure ZnPS3 / NC@C, which is the egg yolk double-shell structure zinc thiophosphate material.
2. The method for preparing the yolk-double-shell structured zinc thiophosphate material as described in claim 1, characterized in that, The zinc source includes zinc nitrate, zinc acetate, zinc chloride, or zinc sulfate; And / or, the solvent 1 includes anhydrous methanol; And / or, the molar ratio of the 2-methylimidazole to the zinc source is 3-8:1; And / or, the heating reaction is carried out at a temperature of 40-80°C for 4-12 hours.
3. The method for preparing the yolk-double-shell structured zinc thiophosphate material as described in claim 1, characterized in that, The mixed solvent is a mixture of anhydrous methanol and water; And / or, the ratio of the ZIF-8 precursor, the CTAB, the resorcinol, the ammonia, and the formaldehyde is 1g:2-3g:0.4-1.6g:1-3mL:0.5-3mL; And / or, after adding CTAB, resorcinol and ammonia, stir the reaction for 20-40 minutes; And / or, after adding formaldehyde, continue stirring for 6-12 hours.
4. The method for preparing the yolk-double-shell structured zinc thiophosphate material as described in claim 1, characterized in that, Solvent 2 includes anhydrous methanol; And / or, the mass ratio of the ZIF-8@RF precursor to the tannic acid is 0.6:0.8-1.2; And / or, the stirring etching time is 30-120 minutes.
5. The method for preparing the yolk-double-shell structured zinc thiophosphate material as described in claim 1, characterized in that, The steps of simultaneously carbonizing and sulfiding the egg yolk double-shell structure ZIF-8 / TA-Zn@RF in a sulfur-containing atmosphere include: placing the egg yolk double-shell structure ZIF-8 / TA-Zn@RF downstream of a tube furnace, placing sulfur powder upstream of the tube furnace, introducing inert gas, and then heating to 350-450℃ for simultaneous carbonization and sulfidation. And / or, the step of phosphorus sulfidation treatment of the egg yolk double-shell structure ZnS / NC@C under a phosphorus-sulfur atmosphere includes: placing the egg yolk double-shell structure ZnS / NC@C in the downstream temperature zone of a dual-temperature zone tube furnace, placing the phosphorus-sulfur powder in the upstream temperature zone of the dual-temperature zone tube furnace, setting the upstream temperature zone temperature to 280-330℃ and the downstream temperature zone temperature to 450-600℃, introducing inert gas, and then simultaneously starting to heat up the upstream and downstream temperature zones, and holding the temperature after heating to the set temperature for phosphorus sulfidation treatment.
6. The method for preparing the yolk-double-shell structured zinc thiophosphate material as described in claim 5, characterized in that, The mass ratio of the egg yolk double-shell structure ZIF-8 / TA-Zn@RF to the sulfur powder is 0.5:2-4; And / or, the simultaneous carbonization and sulfidation treatment takes 2-4 hours.
7. The method for preparing the yolk-double-shell structured zinc thiophosphate material as described in claim 5, characterized in that, The mass ratio of phosphorus to sulfur in the sulfur-phosphorus powder is 1-2:1-3; And / or, the mass ratio of the egg yolk double-shell structure ZnS / NC@C to the sulfur-phosphorus powder is 0.1:1-2; And / or, the phosphorus sulfidation treatment time is 1-4 hours.
8. A zinc thiophosphate material with a yolk double-shell structure prepared by a method according to any one of claims 1-7.
9. The application of the egg yolk double-shell structure zinc thiophosphate material as described in claim 8 in the preparation of sodium-ion battery anodes.
10. A sodium-ion battery negative electrode, characterized in that, The raw materials include the zinc thiophosphate material with a yolk double-shell structure as described in claim 8.