Tellurium-doped copper sulfide-based nano composite material with core-shell structure as well as preparation method and application thereof

Abstract

The invention discloses a tellurium-doped copper sulfide-based nano composite material with a core-shell structure as well as a preparation method and application thereof, and belongs to the technical field of zinc ion battery negative electrode materials. The method comprises the following steps: dissolving a copper source, a sulfur source, a carbon source and a tellurium source in a mixed solution of deionized water and ethylene glycol, uniformly stirring and mixing, carrying out hydrothermal reaction and centrifugal cleaning, collecting a precipitation product, and carrying out vacuum drying; and carrying out calcination reaction to obtain the tellurium-doped copper sulfide-based nano composite material with the core-shell structure. The inner-layer microspheres are microspheres formed by stacking tellurium-doped copper sulfide flower-shaped nanosheets; and the outer coating layer is a carbon layer. Through the synergistic effect of tellurium doping and carbon coating, the electron conduction and the structural stability of the material are effectively enhanced, and the cycle performance and the rate capability of the aqueous zinc ion battery are remarkably improved. As a negative electrode of the zinc ion battery, the material can effectively improve cyclic reversibility, has remarkable reversible capacity, improves the performance of the zinc ion battery, and is suitable for industrial production and large-scale energy storage.

Description

Technical Field

[0001] This invention belongs to the technical field of zinc-ion battery anode materials, specifically relating to tellurium-doped copper sulfide-based nanocomposite materials with core-shell structure, their preparation methods, and applications. Background Technology

[0002] In recent years, to address the dual pressures of the environment and energy sectors, countries worldwide have actively developed and utilized new energy sources as a crucial strategy for sustainable development. To slow the consumption of traditional energy sources such as coal, oil, and natural gas and promote sustainable social development, it is essential to actively develop energy-saving and emission-reduction technologies, continuously explore energy diversification, and develop new energy sources. However, renewable energy is intermittent, necessitating the development of efficient energy storage devices for the rational storage and output of energy. Among these, electrochemical energy storage has attracted widespread attention due to its advantages such as low cost, high energy efficiency, high power density, long lifespan, and economic viability. With the continuous improvement of battery technology, devices using batteries as the primary energy source or for energy storage have been widely applied. Aqueous zinc-ion batteries (ZIBs) have garnered significant attention due to their economic efficiency, high ionic conductivity, inherent safety, and high theoretical energy storage capacity, playing a key role in designing next-generation energy storage battery systems with high safety, low cost, and long lifespan. However, the application of ZIBs battery anodes faces numerous challenges, such as unavoidable zinc dendrite formation, corrosion passivation, hydrogen evolution reaction (HER), and electrolyte moisture loss, which weaken cycle stability, reduce coulombic efficiency, and severely limit the practical application of high-performance ZIBs. To overcome these challenges, much research has focused on innovative improvements to the anode of ZIBs (zinc-in-the-leaf) batteries. Examples include covering the electrode surface with a protective coating to suppress dendrite growth, adding special electrolytes to aqueous electrolytes, and developing high-capacity anode materials for ZIBs that suppress dendrite growth. This type of research aims to enhance the electrochemical performance of ZIBs by increasing energy storage and reducing discharge voltage.

[0003] Copper-based compounds are considered potential candidates for ZIBs anode materials due to their high specific capacity and excellent cycle stability. Copper sulfide (CuS), as a transition metal sulfide, has a layered structure (interlayer spacing of approximately 8.2 Å), with the layers bonded by van der Waals forces, forming a Zn anode. 2+ It provides ample diffusion channels, promoting rapid ion transport; the metal-sulfur bond is relatively weak, and the electronic conductivity is high, which is conducive to charge transfer and conversion reactions. Based on the high-capacity conversion reaction mechanism, the energy density of ZIBs can be improved. Due to its high specific capacity and excellent cycling stability, CuS materials in the ZIB field have gradually attracted more and more attention. However, although copper sulfide-based materials have shown many advantages at the theoretical level, they still face many thorny problems in practical applications. First, as a conversion electrode material, CuS undergoes crystal structure reconstruction during charge and discharge (such as Cu...). 2+With S 2- The changes in the bonding state of copper sulfide (ZIBs) are accompanied by a certain volume expansion and contraction. If this volume effect is not effectively mitigated, it will lead to the pulverization and detachment of the electrode material, destroying the integrity of the electrode structure and ultimately causing a decline in cycle performance. Secondly, copper sulfide itself has poor electrical conductivity and low electronic conductivity, which directly restricts the electron transport efficiency in the electrode material, making it difficult to improve the rate performance of the battery. In addition, copper sulfide may dissolve during cycling, especially when the electrolyte penetrates into the material. The copper ions generated by dissolution may migrate to the surface of the negative electrode and deposit, forming dendrites, thereby threatening the safety performance of the battery. These inherent defects greatly hinder the practical application of copper sulfide as a high-performance ZIBs negative electrode material.

[0004] Therefore, there are still many challenges in manufacturing novel ZIBs anodes using CuS as the main material, and the materials still need to be optimized and improved to achieve high-performance ZIBs. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure, its preparation method and application, so as to solve the technical problems of easy generation of zinc dendrites, uncontrollable self-corrosion of metallic zinc anode, low capacity of zinc-ion battery and unsatisfactory rate performance during the cycling process of existing zinc-ion battery anode materials.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure, comprising: an inner layer of microspheres and an outer coating layer; the inner layer of microspheres is composed of stacked tellurium-doped copper sulfide flower-like nanosheets; and the outer coating layer is a carbon layer.

[0007] Preferably, the microspheres formed by stacking tellurium-doped copper sulfide flower-shaped nanosheets are the basic units of tellurium-doped copper sulfide-based nanocomposites with a core-shell structure; the diameter of the microspheres formed by stacking tellurium-doped copper sulfide flower-shaped nanosheets is 0.1~10 μm; and the thickness of the tellurium-doped copper sulfide flower-shaped nanosheets is 1~100 nm.

[0008] Preferably, in the tellurium-doped copper sulfide flower-shaped nanosheets, each mole of copper sulfide contains 0.05~0.1 mol of tellurium.

[0009] Preferably, the carbon layer is amorphous carbon.

[0010] This invention also discloses a method for preparing tellurium-doped copper sulfide-based nanocomposites with a core-shell structure, comprising the following steps: Copper, sulfur, carbon, and tellurium sources were dissolved in a mixture of deionized water and ethylene glycol, stirred and mixed evenly, subjected to hydrothermal reaction, centrifuged and washed, the precipitate was collected and vacuum dried; then calcined to obtain tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure.

[0011] Preferably, the ratio of copper source, sulfur source, carbon source, tellurium source, and deionized water and ethylene glycol mixture is (0.1~5) g : (0.1~5) g : (0.1~5) g : (0.01~0.5) g : 120 mL; In the mixture of deionized water and ethylene glycol, the volume ratio of deionized water to ethylene glycol is 1:(3~8).

[0012] Preferably, the copper source is any one of copper sulfate, copper nitrate, and copper chloride; the sulfur source is any one of thiourea and thioacetamide; the carbon source is any one of glucose and dopamine solution; and the tellurium source is any one of sodium tellurite and potassium tellurate.

[0013] Preferably, the hydrothermal reaction temperature is 100~180℃ and the hydrothermal reaction time is 6~48 h; the vacuum drying conditions are 50~80℃ vacuum drying for 10~24 h.

[0014] Preferably, the calcination temperature is 500~1000℃; the calcination time is 6~48 h.

[0015] This invention also discloses the application of the above-mentioned tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure in the preparation of anode materials for aqueous zinc-ion batteries.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure. It consists of an inner layer of microspheres and an outer coating layer. The inner microspheres are formed by stacking tellurium-doped copper sulfide flower-like nanosheets. Tellurium and sulfur belong to the same group (Group 6) in the periodic table, possessing similar atomic radii and electronegativity. Tellurium doping can specifically alter the electronic structure of copper sulfide, adjusting the band structure to improve electronic conductivity, while simultaneously introducing lattice defects to increase active sites. The microsphere structure formed by the stacked flower-like nanosheets utilizes the short ion diffusion path characteristics of the nanoscale to promote rapid electron and ion transport in battery reactions, improving rate performance. The abundant pores formed by the tightly assembled nanosheets provide sufficient active sites, effectively promoting reactant mass transfer and discharge product deposition. Furthermore, the overall structure of the microspheres can buffer volume changes during charging and discharging, preventing material pulverization and detachment. The outer coating layer is a carbon layer, which tightly confines the stacked tellurium-doped copper sulfide nanosheets into a limited space. This mechanical constraint enhances the structural stability during the zinc ion insertion and extraction process, preventing damage caused by volume expansion. At the same time, the good electronic conductivity of the carbon layer ensures efficient electron transport and reduces side reactions such as copper sulfide dissolution and copper ion migration.

[0017] Furthermore, by setting microspheres as the basic unit and limiting their size parameters, stress is uniformly distributed during zinc ion insertion and extraction, preventing material pulverization and structural failure caused by localized stress concentration. Simultaneously, the ultrathin thickness of the nanosheets promotes rapid ion transport, and the abundant porous structure formed by stacking enhances electrochemical reaction efficiency. This effectively alleviates the problems of material pulverization and structural collapse caused by uneven volume expansion, while improving ion diffusion and electron transport efficiency, thereby enhancing the battery's cycle life and rate performance.

[0018] Furthermore, in the tellurium-doped copper sulfide flower-shaped nanosheets, each mole of copper sulfide contains 0.05~0.1 mol of tellurium. Utilizing the chemical similarity between tellurium and sulfur, both belonging to Group 6, tellurium atoms effectively replace sulfur atoms in the copper sulfide lattice. Among them, 0.05 mol ensures sufficient tellurium atoms to enhance electronic conductivity and promote rapid zinc ion transport, while 0.1 mol effectively suppresses the increased volume expansion caused by excessive doping. Thus, during the zinc ion insertion and extraction process, the integrity of the electrode structure is maintained synergistically, preventing the material from pulverizing and falling off.

[0019] Furthermore, by using amorphous carbon as the outer coating layer, its amorphous structure endows the material with excellent flexibility and deformability, enabling it to closely adhere to the surface of the inner tellurium-doped copper sulfide microspheres. During the volume changes caused by repeated insertion and extraction of zinc ions, this coating layer can dynamically buffer stress, preventing cracking or peeling, thereby maintaining the integrity of the overall electrode structure. At the same time, the continuous network structure of amorphous carbon maintains high electronic conductivity, ensuring rapid charge transfer within the electrode material and avoiding rate performance degradation due to insufficient conductivity.

[0020] The present invention provides a method for preparing tellurium-doped copper sulfide-based nanocomposite materials with a core-shell structure. By combining tellurium-doped copper sulfide microspheres with a carbon coating layer in a synergistic manner, the volume expansion and electron transport barriers of the negative electrode material during charge and discharge are effectively alleviated, thereby improving the cycle stability and rate performance of aqueous zinc-ion batteries. The high boiling point and reducing properties of ethylene glycol are used to regulate the reaction system, enabling the components to form a uniformly dispersed precursor solution in the mixed solvent, avoiding rapid precipitation and structural inhomogeneity caused by a single water solvent. Stirring ensures uniform mixing and guarantees molecular-level contact of the reactants, reducing local concentration differences and improving reaction uniformity. Hydrothermal reaction in a closed environment promotes the incorporation of tellurium atoms into the copper sulfide lattice, while simultaneously inducing the self-assembly of copper sulfide nanosheets into a flower-like stacked microsphere structure. This structure effectively accommodates volume changes during zinc ion insertion and extraction, reducing structural stress. Centrifugal washing removes unreacted impurities and byproducts, ensuring the purity of intermediate products. Vacuum drying in a low-temperature vacuum environment removes moisture, preventing material oxidation or nanostructure collapse. Calcination in situ carbonizes the carbon source to form a continuous amorphous carbon layer, tightly coating the surface of the tellurium-doped copper sulfide microspheres. This carbon layer not only enhances electron conductivity but also physically restricts the dissolution and pulverization of copper sulfide during cycling. Through the above technical solution, the inner tellurium-doped copper sulfide provides a high-capacity active center, and the outer carbon coating layer synergistically buffers the volume effect and accelerates electron transport, thus solving the problems of poor cycle stability, low capacity and poor rate performance of copper sulfide-based anode materials in aqueous zinc-ion batteries.

[0021] Furthermore, by precisely controlling the raw material ratio and solvent composition, the reaction system achieves dynamic equilibrium. Copper, sulfur, and carbon sources are used within defined ranges to ensure the formation of flower-like nanosheet stacking structures. Precise control of the tellurium source enables appropriate doping to enhance electron migration. A 120 mL mixed solution maintains the concentration to promote directional stacking, while a water-to-ethylene glycol volume ratio of 1:(3~8) optimizes solvent properties, allowing for carbon source pre-adsorption and preventing over-carbonization. This ensures uniform embedding of tellurium into the lattice and directional deposition of the carbon source, ultimately achieving high integrity of the core-shell structure and tight interfacial bonding. In this system, ethylene glycol acts not only as a solvent but also as a reducing agent and morphology guide. A ratio that is too low (e.g., <1:3) leads to excessively strong reducing power, causing nanosheets to grow too quickly and making it difficult to stack into spheres; a ratio that is too high (e.g., >1:8) results in excessive viscosity, which is detrimental to ion diffusion.

[0022] Furthermore, by selecting specific types of copper, sulfur, carbon, and tellurium sources, the stability and controllability of each reactant during the hydrothermal reaction were ensured. The solubility of the copper source ensured a uniform supply of copper ions, while the organic properties of the sulfur source regulated the release rate of sulfur ions. Their synergistic effect promoted the orderly stacking of tellurium-doped copper sulfide flower-like nanosheets to form a microsphere structure. The choice of carbon source directly affected the quality of the carbon coating layer during subsequent calcination. Glucose formed a continuous carbon layer, while dopamine enhanced interfacial bonding, jointly ensuring the uniformity and density of the outer coating. The precise selection of the tellurium source achieved uniform doping of tellurium in the copper sulfide lattice, altering the electronic structure of the material. Overall, the optimized combination of these raw materials resulted in tellurium-doped copper sulfide-based nanocomposites exhibiting excellent electronic conductivity and structural stability, effectively solving the capacity decay and rate performance degradation problems faced by aqueous zinc-ion battery anode materials during cycling.

[0023] Furthermore, by limiting the hydrothermal reaction temperature to the range of 100–180 °C, tellurium atoms can be effectively embedded into the copper sulfide lattice and induce the directional self-assembly of flower-like nanosheets, while suppressing insufficient reaction kinetics or excessive dissolution. By setting the hydrothermal reaction time to 6–48 h, the formation of tellurium-doped copper sulfide microspheres is ensured without structural collapse, maintaining the uniformity of nanosheet stacking. Vacuum drying at 50–80 °C for 10–24 h utilizes the low-temperature environment to suppress thermal stress damage to the precursor structure, while also achieving complete removal of the mixed solvent, preventing residual moisture from generating bubbles or carbon layer defects during subsequent calcination. This ensures the high-quality construction of tellurium-doped copper sulfide flower-like nanosheet stacked microspheres and precursor stability, allowing the outer amorphous carbon layer to densely coat the inner microspheres.

[0024] Furthermore, by controlling the calcination temperature at 500–1000℃ and maintaining the calcination time at 6–4 hours, a high-quality amorphous carbon coating layer is formed during the pyrolysis of the carbon source. This layer tightly encapsulates the inner tellurium-doped copper sulfide microspheres, effectively buffering volume changes and providing efficient electron transport channels during zinc ion insertion and extraction. Ultimately, this ensures the composite material maintains structural integrity and high electrochemical activity during battery cycling. This effectively avoids problems such as uneven carbon layer structure and material thermal decomposition, ensuring the continuity and density of the outer carbon coating layer, thereby improving the electronic conductivity and structural stability of the composite material and enhancing the cycle performance and rate performance of aqueous zinc-ion batteries.

[0025] This invention discloses a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure. In preparing anode materials for aqueous zinc-ion batteries, this material combines tellurium-doped copper sulfide flower-like nanosheets stacked into microspheres with an amorphous carbon coating layer in a core-shell structure. Utilizing the fact that tellurium and sulfur both belong to Group 6 of the periodic table, electronic structure regulation is achieved. Simultaneously, the carbon layer mechanically constrains the microspheres, effectively suppressing zinc dendrite growth, mitigating structural pulverization caused by volume expansion, and reducing side reactions caused by copper sulfide dissolution. This significantly improves the cycle stability and rate performance of aqueous zinc-ion batteries. Tellurium doping modulates the band structure through similar atomic radii and electronegativity, enhancing electronic conductivity and introducing lattice defects to increase active sites. The microsphere structure formed by stacked flower-like nanosheets constructs a porous network within a 0.1–10 μm scale, shortening the zinc ion diffusion path and providing sufficient reaction interfaces. The outer carbon coating layer tightly confines the microspheres within a limited space, buffering volume stress changes during zinc ion insertion and extraction, preventing active material detachment, and synergistically suppressing copper ion migration and dendrite formation. This composite material maintains the integrity of the electrode structure during charge-discharge cycles, reduces capacity decay caused by increased contact interface resistance, and ultimately achieves a comprehensive improvement in the cycle reversibility and capacity stability of aqueous zinc-ion battery anode materials. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the preparation process of the tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure disclosed in this invention. Figure 2 The images shown are SEM images of the tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure disclosed in Example 1 of this invention; where (a) is a low-magnification SEM image and (b) is a high-magnification SEM image. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0029] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0030] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0031] Unless otherwise specified, the components or preferred components involved in this invention can be combined with each other to form new technical solutions.

[0032] In this invention, unless otherwise specified, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6~22" indicates that all real numbers between "6~22" have been listed in this document, and "6~22" is simply a shortened representation of these numerical combinations.

[0033] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0034] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0035] In this invention, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0036] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0037] This invention discloses a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure, comprising an inner layer of microspheres and an outer coating layer; the inner layer of microspheres is composed of stacked tellurium-doped copper sulfide flower-like nanosheets, and the outer coating layer is a carbon layer.

[0038] This invention discloses a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure, comprising an inner layer of microspheres and an outer coating layer; the inner layer consists of microspheres formed by stacked tellurium-doped copper sulfide flower-like nanosheets, and the outer coating layer is a carbon layer. The outer carbon coating layer tightly confines the microspheres formed by stacked tellurium-doped copper sulfide nanosheets within a limited space, thereby improving the Zn content. 2+ The structural stability of copper sulfide during the insertion and extraction process, the carbon coating with good electronic conductivity, and tellurium doping ensure the excellent rate performance of the copper sulfide anode. This invention solves the technical problems of poor cycle stability and low capacity of existing aqueous zinc-ion battery copper sulfide anode materials.

[0039] Microspheres formed by stacking tellurium-doped copper sulfide flower-like nanosheets are the basic unit of tellurium-doped copper sulfide-based nanocomposites with a core-shell structure. The diameter of the inner microspheres is 0.1~10μm, and the thickness of the tellurium-doped copper sulfide flower-like nanosheets is about 1~100 nm.

[0040] Microspheres, formed by stacking tellurium-doped copper sulfide nanosheets, serve as the basic unit of tellurium-doped copper sulfide-based nanocomposites. The diameter of these microspheres ranges from 0.1 to 10 μm, while the thickness of the tellurium-doped copper sulfide nanosheets ranges from 1 to 100 nm. The nanoscale design offers the advantage of short ion diffusion paths, ensuring rapid electron / ion diffusion during battery reactions and thus improving rate performance. The tightly packed nanosheets provide sufficient active sites and abundant pores, effectively promoting mass transfer of reactants and deposition of discharge products.

[0041] The tellurium doping content is 0.01-0.5 mol of tellurium per mol of copper sulfide. The carbon layer is amorphous carbon.

[0042] Tellurium and sulfur are both in Group 6 of the periodic table and have similar atomic radii and electronegativity. Doping tellurium atoms into the copper sulfide lattice can change the electronic structure of copper sulfide, adjust the band structure, increase electronic conductivity, and introduce lattice defects to increase active sites, thereby further improving the battery performance of copper sulfide anode materials.

[0043] This invention also discloses a method for preparing tellurium-doped copper sulfide-based nanocomposites with a core-shell structure, comprising the following steps: S1. Dissolve the copper source, sulfur source, carbon source and tellurium source in a mixture of deionized water and ethylene glycol (the volume ratio of deionized water and ethylene glycol is 1:(3~8)). After stirring and mixing evenly, carry out a hydrothermal reaction. After the reaction is completed, centrifuge and wash, collect the precipitate, and vacuum dry the obtained precipitate at 50~80℃ for 10~24h.

[0044] S2. The precipitate obtained in step S1 is subjected to calcination reaction to obtain tellurium-doped copper sulfide-based nanocomposite material with core-shell structure.

[0045] This invention discloses a method for preparing tellurium-doped copper sulfide-based nanocomposite materials with a core-shell structure. The method involves dissolving copper, sulfur, tellurium, and carbon sources in a mixed solvent of deionized water and ethylene glycol, stirring until homogeneous, and then performing a hydrothermal reaction. After the reaction, the mixture is centrifuged, washed, and the precipitated product is collected. The obtained precipitated product is then calcined and annealed to obtain the tellurium-doped copper sulfide-based nanocomposite material. This method is simple, low-cost, and the tellurium doping alleviates the low performance problem of copper sulfide anodes, improves the performance of zinc-ion batteries, and is suitable for industrial production and large-scale energy storage applications.

[0046] In step S1, the amount of copper source added to each 120 mL of deionized water and ethylene glycol mixed solvent is 0.1~5 g, the amount of sulfur source added is 0.1~5 g, the amount of carbon source added is 0.1~5 g, and the amount of tellurium source added is 0.01~0.5 g; the hydrothermal reaction temperature is 100~180 ℃, and the hydrothermal reaction time is 6~48 h.

[0047] The copper source is any one of copper sulfate, copper nitrate, and copper chloride; the carbon source is any one of glucose and dopamine solution; the sulfur source is any one of thiourea and thioacetamide; and the tellurium source is any one of sodium tellurite and potassium tellurate.

[0048] The hydrothermal reaction temperature is 100~180 ℃; the hydrothermal reaction time is 6~48 h.

[0049] In step S2, the calcination reaction temperature is 500~1000℃; the calcination reaction time is 6~48 h.

[0050] In each 100 mL of ethylene glycol and 20 mL of deionized water mixed solvent, the amount of copper source added is 0.1–5 g, the amount of sulfur source added is 0.1–5 g, the amount of carbon source added is 0.1–5 g, and the amount of tellurium source added is 0.01–0.5 g; the hydrothermal reaction temperature is 100–180 °C, and the hydrothermal reaction time is 6–48 h; within the given reaction conditions, tellurium-doped copper sulfide-based nanocomposite intermediates can be obtained. In step S2, the calcination reaction temperature is 500–1000 °C, and the calcination reaction time is 6–48 h; within the given reaction conditions, tellurium-doped copper sulfide-based nanocomposite materials can be obtained.

[0051] This invention also discloses the application of the aforementioned tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure in the preparation of anode materials for aqueous zinc-ion batteries. This tellurium-doped copper sulfide-based nanocomposite material can effectively buffer volume changes in the active material and synergistically enhance the material's capacity performance, thereby improving zinc-ion storage performance and exhibiting certain advantages in zinc-ion battery anode material applications.

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0053] Example 1 A method for preparing a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure includes the following steps: S1. Dissolve 0.1g copper nitrate, 0.1g thiourea, and 0.1g glucose in a mixture of 20mL deionized water and 60mL ethylene glycol while stirring. Then, dissolve 0.01g sodium tellurite in 40mL ethylene glycol while stirring. After mixing the two solutions thoroughly, transfer them to a hydrothermal reactor and react at 100℃ for 6 hours. After the reaction is complete, centrifuge and wash to collect the precipitate. S2. The product obtained in step S1 is calcined and annealed in a tube furnace at 500°C for 6 hours to obtain tellurium-doped copper sulfide-based nanocomposite material.

[0054] The electrochemical testing methods for the obtained tellurium-doped copper sulfide-based nanocomposites are as follows: The electrochemical performance of the negative electrode material was studied using a coin cell. The negative electrode was formulated into a slurry with an active material: carbon black: PVDF ratio of 7:2:1. This slurry was then uniformly coated onto a stainless steel mesh and dried in a vacuum oven at 60 °C for 12 h to obtain the electrode for the experimental battery. Zinc foil was used as the counter electrode, a 2.0 M zinc sulfate aqueous solution as the electrolyte, and glass fiber as the separator. Charge-discharge cycle tests were performed on the coin cell.

[0055] Example 2 A method for preparing a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure includes the following steps: S1. Dissolve 5g copper nitrate, 5g thiourea, and 5g glucose in a mixture of 20mL deionized water and 60mL ethylene glycol while stirring. Then, dissolve 0.05g sodium tellurite in 40mL ethylene glycol while stirring. After mixing the two solutions thoroughly, transfer them to a hydrothermal reactor and react at 180℃ for 48 hours. After the reaction is complete, centrifuge and wash to collect the precipitate. S2. The product obtained in step S1 is calcined and annealed in a tube furnace at 1000℃ for 48 hours to obtain tellurium-doped copper sulfide-based nanocomposite material.

[0056] The electrochemical testing method for the obtained tellurium-doped copper sulfide-based nanocomposite material is the same as that in Example 1.

[0057] Example 3 A method for preparing a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure includes the following steps: S1. Dissolve 4g copper nitrate, 4g thiourea, and 4g glucose in a mixture of 20mL deionized water and 60mL ethylene glycol while stirring. Then, dissolve 0.4g sodium tellurite in 40mL ethylene glycol while stirring. After mixing the two solutions thoroughly, transfer them to a hydrothermal reactor and react at 170℃ for 36 hours. After the reaction is complete, centrifuge and wash to collect the precipitate. S2. The product obtained in step S1 is calcined and annealed in a tube furnace at 900°C for 36 hours to obtain tellurium-doped copper sulfide-based nanocomposite material.

[0058] The electrochemical testing method for the obtained tellurium-doped copper sulfide-based nanocomposite material is the same as that in Example 1.

[0059] Example 4 A method for preparing a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure includes the following steps: S1. Dissolve 3g copper nitrate, 3g thiourea, and 3g glucose in a mixture of 20mL deionized water and 60mL ethylene glycol while stirring. Then, dissolve 0.3g sodium tellurite in 40mL ethylene glycol while stirring. After mixing the two solutions thoroughly, transfer them to a hydrothermal reactor and react at 160℃ for 24 hours. After the reaction is complete, centrifuge and wash to collect the precipitate. S2. The product obtained in step S1 is calcined and annealed in a tube furnace at 800°C for 24 hours to obtain tellurium-doped copper sulfide-based nanocomposite material.

[0060] The electrochemical testing method for the obtained tellurium-doped copper sulfide-based nanocomposite material is the same as that in Example 1.

[0061] Example 5 A method for preparing a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure includes the following steps: S1. Dissolve 2g copper nitrate, 2g thiourea, and 2g glucose in a mixture of 20mL deionized water and 60mL ethylene glycol while stirring. Then, dissolve 0.2g sodium tellurite in 40mL ethylene glycol while stirring. After mixing the two solutions thoroughly, transfer them to a hydrothermal reactor and react at 140℃ for 18 hours. After the reaction is complete, centrifuge and wash to collect the precipitate. S2. The product obtained in step S1 is calcined and annealed in a tube furnace at 700°C for 18 hours to obtain tellurium-doped copper sulfide-based nanocomposite material.

[0062] The electrochemical testing method for the obtained tellurium-doped copper sulfide-based nanocomposite material is the same as that in Example 1.

[0063] Example 6 A method for preparing a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure includes the following steps: S1. Dissolve 1g of copper nitrate, 1g of thiourea, and 1g of glucose in a mixture of 20mL of deionized water and 60mL of ethylene glycol while stirring. Then, dissolve 0.1g of sodium tellurite in 40mL of ethylene glycol while stirring. After mixing the two solutions thoroughly, transfer them to a hydrothermal reactor and react at 120℃ for 12 hours. After the reaction is complete, centrifuge and wash to collect the precipitate. S2. The product obtained in step S1 is calcined and annealed in a tube furnace at 600°C for 12 hours to obtain tellurium-doped copper sulfide-based nanocomposite material.

[0064] The electrochemical testing method for the obtained tellurium-doped copper sulfide-based nanocomposite material is the same as that in Example 1.

[0065] Example 7 A method for preparing a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure includes the following steps: S1. Under stirring conditions, 2.5 g of copper sulfate, 2.5 g of thioacetamide, and 2.5 g of dopamine solution were sequentially dissolved in a solution composed of 20 mL of deionized water and 100 mL of ethylene glycol (volume ratio 1:5). Subsequently, under continuous stirring, 0.25 g of potassium tellurate was dissolved in an appropriate amount of ethylene glycol. After thoroughly mixing the two solutions, the mixture was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 140 °C for 24 h. After the reaction was completed, the reaction system was centrifuged to separate the precipitate. The precipitate was then washed multiple times with a suitable cleaning agent. Finally, the precipitate was collected and dried in a vacuum environment at 50 °C for 24 h.

[0066] S2. Place the dried product obtained in step S1 in a tube furnace for calcination and annealing treatment. Calcinate at 750°C for 24 hours. After the reaction is completed, allow it to cool naturally to room temperature to obtain tellurium-doped copper sulfide-based nanocomposite material.

[0067] The electrochemical testing method for the obtained tellurium-doped copper sulfide-based nanocomposite material is the same as that in Example 1.

[0068] Example 8 A method for preparing a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure includes the following steps: S1. Under stirring, 0.5g of copper chloride, 0.5g of thioacetamide, and 0.5g of dopamine solution were sequentially added to a solution (volume ratio 1:8) formed by mixing 13mL of deionized water and 107mL of ethylene glycol, and stirred until fully dissolved. Simultaneously, in another container, 0.025g of potassium tellurate was dissolved in an appropriate amount of ethylene glycol under stirring. After thoroughly mixing these two solutions, they were transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 120℃ for 12 hours. After the reaction was completed, the reaction system was centrifuged to separate the precipitate, which was then washed multiple times with a suitable cleaning agent. The precipitate was collected and dried in a vacuum environment at 80℃ for 10 hours.

[0069] S2. The dried product obtained in step S1 is placed in a tube furnace for calcination and annealing at 600°C for 12 hours. After the reaction is completed, the product is allowed to cool naturally to room temperature to obtain tellurium-doped copper sulfide-based nanocomposite material.

[0070] The electrochemical testing method for the obtained tellurium-doped copper sulfide-based nanocomposite material is the same as that in Example 1.

[0071] See Figure 1 This diagram illustrates the preparation process of the tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure disclosed in this invention. As shown in the diagram, the preparation route of this invention mainly includes three key stages: raw material dissolution, hydrothermal synthesis, and calcination. First, copper, sulfur, tellurium, and carbon sources are dissolved and dispersed in a mixed solvent system composed of deionized water and ethylene glycol to construct a homogeneous reaction precursor solution. Subsequently, under hydrothermal reaction conditions, the components undergo chemical reactions and self-assemble to form spherical intermediate products. Finally, the intermediate products are calcined to induce in-situ carbonization of the carbon source to form a coating layer, simultaneously optimizing the structure of the tellurium-doped copper sulfide crystals, ultimately obtaining a tellurium-doped copper sulfide-based nanocomposite material that maintains a micron-sized spherical morphology. The entire process visually demonstrates the integrated synthesis path from liquid-phase precursor to solid-phase core-shell structured composite material.

[0072] Figure 2 The images show SEM images of the tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure disclosed in Example 1 of this invention; (a) is a low-magnification SEM image; and (b) is a high-magnification SEM image. As can be seen from the images, the obtained product exhibits a regular spherical morphology, with a relatively uniform particle size distribution, good dispersibility, and no obvious agglomeration. According to Figure (a), the diameter of the microspheres is approximately 3.5–4.5 μm. Further analysis of the high-magnification microstructure in Figure (b) reveals that the microspheres are not smooth, solid spheres, but rather a hierarchical flower-like structure formed by the interlacing and stacking of numerous ultrathin nanosheets. These nanosheets have clear edges and a thickness on the order of tens of nanometers, and the stacking between the nanosheets forms a rich internal porous structure. This unique flower-like stacking structure not only constitutes a stable micron-scale framework but also helps to increase the specific surface area of ​​the material, providing abundant channels for electrolyte wetting and rapid ion transport.

[0073] In summary, this invention discloses a tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure, its preparation method, and its applications. This composite material uses tellurium (Te)-doped copper sulfide microspheres as the core and an amorphous carbon shell as the outer layer. The preparation method includes: dissolving a copper source, a sulfur source, a tellurium source, and a carbon source in a mixed solvent, obtaining a precursor through a hydrothermal reaction, followed by a calcination reaction to achieve in-situ carbonization and coating of the carbon source, ultimately obtaining the core-shell structured composite material. This invention effectively enhances the electronic conductivity and structural stability of the material through the synergistic effect of tellurium doping and carbon coating, significantly improving the cycle performance and rate performance of aqueous zinc-ion batteries. The preparation process is simple. In the application of tellurium-doped copper sulfide-based nanocomposite materials as zinc-ion battery anode materials, it can effectively improve cycle reversibility, exhibit significant reversible capacity, improve zinc-ion battery performance, and is suitable for industrial production and large-scale energy storage. It has certain advantages in the application of zinc-ion battery anode materials.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure, characterized in that, include: The inner layer consists of microspheres and an outer coating layer; the inner layer consists of microspheres formed by stacking tellurium-doped copper sulfide flower-shaped nanosheets; the outer coating layer is a carbon layer.

2. The tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure according to claim 1, characterized in that, The microspheres formed by stacking tellurium-doped copper sulfide flower-shaped nanosheets are the basic unit of tellurium-doped copper sulfide-based nanocomposite materials with a core-shell structure; the diameter of the microspheres formed by stacking tellurium-doped copper sulfide flower-shaped nanosheets is 0.1~10 μm; the thickness of the tellurium-doped copper sulfide flower-shaped nanosheets is 1~100 nm.

3. The tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure according to claim 1, characterized in that, The tellurium-doped copper sulfide flower-shaped nanosheets contain 0.05~0.1 mol of tellurium per mole of copper sulfide.

4. The tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure according to claim 1, characterized in that, The carbon layer is amorphous carbon.

5. The method for preparing the tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure according to any one of claims 1 to 4, characterized in that, Includes the following steps: Copper, sulfur, carbon, and tellurium sources were dissolved in a mixture of deionized water and ethylene glycol, stirred and mixed evenly, subjected to hydrothermal reaction, centrifuged and washed, the precipitate was collected and vacuum dried; then calcined to obtain tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure.

6. The method for preparing tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure according to claim 5, characterized in that, The ratio of the copper source, sulfur source, carbon source, tellurium source, and the mixture of deionized water and ethylene glycol is (0.1~5) g : (0.1~5) g : (0.1~5) g : (0.01~0.5) g : 120 mL; In the mixture of deionized water and ethylene glycol, the volume ratio of deionized water to ethylene glycol is 1: (3~8).

7. The method for preparing tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure according to claim 5, characterized in that, The copper source is any one of copper sulfate, copper nitrate, and copper chloride; the sulfur source is any one of thiourea and thioacetamide; the carbon source is any one of glucose and dopamine solution; and the tellurium source is any one of sodium tellurite and potassium tellurate.

8. The method for preparing tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure according to claim 5, characterized in that, The hydrothermal reaction temperature is 100~180℃, and the hydrothermal reaction time is 6~48 h; the vacuum drying conditions are 50~80℃ vacuum drying for 10~24 h.

9. The method for preparing the tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure according to claim 5, characterized in that, The calcination reaction temperature is 500~1000℃; the calcination reaction time is 6~48 h.

10. The application of the tellurium-doped copper sulfide-based nanocomposite material with a core-shell structure as described in any one of claims 1 to 4 in the preparation of anode materials for aqueous zinc-ion batteries.

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