A cuprous sulfide / nickel disulfide / carbon composite material, its preparation method, and its application in batteries.

Abstract

This invention provides a cuprous sulfide / nickel disulfide / carbon composite material, its preparation method, and its application in batteries. The preparation method involves dispersing a copper source, a nickel source, polyvinylpyrrolidone, and a sulfur source in a solvent, followed by a hydrothermal reaction to obtain Cu. 1.81 The Cu2S / NiS2 flower-like material is obtained by further annealing. Compared with existing technologies, this invention prepares Cu2S / NiS2 / C nanosphere composite materials through a simple hydrothermal reaction and annealing process. The heterogeneous interface between Cu2S and NiS2 crystals can induce an internal electric field to accelerate ion diffusion kinetics, improve conductivity, and provide abundant reaction sites for sodium energy storage. It exhibits high reversible capacity, high specific capacity, stable cycling performance, and robust rate performance.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery material preparation, specifically relating to a cuprous sulfide / nickel disulfide / carbon composite material, its preparation method, and its application in batteries. The prepared binary metal sulfide Cu2S / NiS2 / C is used as a negative electrode material in sodium-ion batteries. Background Technology

[0002] With the growing global demand for sustainable energy, efficient and reliable energy storage technologies have become a research focus. Among the many energy storage technologies, battery technology occupies an important position. Traditional lithium-ion batteries have achieved great success in portable electronic devices and electric vehicles, but the limited availability and uneven distribution of lithium resources have prompted researchers to actively seek alternative battery technologies.

[0003] Sodium-ion batteries, as a promising energy storage technology, have attracted much attention in recent years. Sodium is abundant, widely distributed, and inexpensive on Earth, giving it a significant resource advantage over lithium. Furthermore, the working principle of sodium-ion batteries is similar to that of lithium-ion batteries, allowing for the application of mature technologies and production experience from lithium-ion batteries to some extent.

[0004] However, sodium-ion batteries still face some performance challenges. For example, the ionic radius of sodium ions is larger than that of lithium ions, which may lead to poorer structural stability of electrode materials during charge and discharge, affecting the battery's cycle life. At the same time, the relatively low energy density of sodium-ion batteries limits their application in certain fields with high energy density requirements. To overcome these challenges, researchers are dedicated to developing novel electrode materials, optimizing battery structures, and improving manufacturing processes to enhance the performance of sodium-ion batteries and better meet the application needs of various fields.

[0005] Therefore, it is essential to provide a new material for sodium-ion batteries and improve its performance. Summary of the Invention

[0006] The purpose of this invention is to provide a cuprous sulfide / nickel disulfide / carbon composite material and its preparation method. A porous nanosheet-like flower-like Cu2S / NiS2 / C composite material is prepared through a simple one-step hydrothermal reaction and annealing process, wherein the bimetallic sulfide Cu2S / NiS2 forms a heterojunction with carbon; it can be used in sodium-ion batteries to improve performance.

[0007] Another objective of this invention is to provide an application of a cuprous sulfide / nickel disulfide / carbon composite material in batteries. By using the cuprous sulfide / nickel disulfide / carbon composite material as an active material to prepare the negative electrode of a sodium-ion battery, a sodium-ion battery can be prepared, which greatly improves the lifespan, cycle stability and battery capacity of sodium-ion batteries.

[0008] The specific technical solution of this invention is as follows:

[0009] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0010] 1) Preparation of Cu by hydrothermal reaction 1.81 S / NiS2 flower-like material;

[0011] 2) Cu 1.81 The S / NiS2 flower-like material was annealed under a protective atmosphere to obtain a Cu2S / NiS2 / C composite material.

[0012] Step 1) Preparation method: Disperse copper source, nickel source, polyvinylpyrrolidone and sulfur source in solvent, and perform hydrothermal reaction to obtain Cu. 1.81 S / NiS2 flower-like material.

[0013] In step 1), the molar ratio of polyvinylpyrrolidone, copper source, nickel source, and sulfur source is 0.03:0.75:0.65-2.25:6; preferably 0.03:0.75:0.68:6; the ratio of copper source to solvent is 0.02-0.05 mmol / mL; the copper source is a soluble copper source, preferably CuSO4·5H2O; the nickel source is a soluble copper source, preferably NiSO4·6H2O or Ni(NO3)2·6H2O; the solvent is ethylene glycol; the sulfur source is a soluble sulfur source, preferably thiourea; the polyvinylpyrrolidone is PVP, K16-18, with a molecular weight M=8000;

[0014] In step 1), the hydrothermal reaction is carried out at 130~170℃ for 2-3 hours; preferably at 160℃ for 2.5 hours.

[0015] In step 1), further, after the hydrothermal reaction, the product is washed 4-6 times with water and 1-2 times with ethanol, centrifuged, and dried; the drying temperature is 40-80℃ and the time is 12-15h.

[0016] Cu prepared in step 1) 1.81 S / NiS2 flower-like materials are formed by the cross-stacking of nanosheets, with a size of 1-3 μm.

[0017] In step 2), the annealing refers to annealing at 300-400℃ for 2 hours, with the preferred temperature being 400℃;

[0018] In step 2), the protective atmosphere refers to an argon atmosphere;

[0019] In step 2), the temperature is raised to 300-400℃ at a heating rate of 2℃ / min for annealing and calcination treatment; preferably, the annealing and calcination treatment is carried out in a tube furnace.

[0020] In the preparation of this invention: Under hydrothermal conditions, the solvent provides a high-temperature and high-pressure reaction environment. The copper and nickel sources dissolve in the solvent, releasing copper and nickel ions. Polyvinylpyrrolidone (PVP), as a surfactant and stabilizer, can adsorb onto the surface of the forming nanoparticles. Thiourea decomposes in the reaction system to produce sulfide ions, which react with copper and nickel ions to generate copper sulfide (Cu₂S) and nickel sulfide (NiS₂) precursors, i.e., Cu. 1.81 S / NiS2. These precursors gradually grow and aggregate in a hydrothermal environment, eventually forming a flower-like morphology due to factors such as anisotropic growth.

[0021] The annealing and calcination process mainly involves heat treatment of the precursor. During high-temperature calcination, the components in the precursor undergo further reactions and phase transformations. For example, copper sulfide (CuS) partially transforms into Cu2S, and nickel sulfide (NiS) transforms into NiS2. Simultaneously, organic materials such as PVP decompose to produce carbon (C), resulting in a Cu2S / NiS2 / C composite material. This process increases the crystallinity of the material and makes its internal structure more stable.

[0022] In the raw materials used, copper and nickel sources are the metal ion sources for the synthesis of copper sulfide and nickel sulfide. Their types (such as different copper and nickel salts) and concentrations affect the copper and nickel content in the final product, thus affecting the material's properties. For example, if the copper source concentration is relatively high, the proportion of Cu2S in the final product may increase. Increasing the concentration of copper or nickel sources may lead to larger flower-like materials. This is because an increased metal ion concentration provides more raw materials for sulfide growth, resulting in faster and larger particle growth. Simultaneously, the ratio of copper to nickel sources also affects the morphology of the composite material; an increased nickel source proportion may alter the petal shape or branching structure of the flower-like material. Therefore, this invention requires controlling an appropriate ratio of nickel to copper sources. Polyvinylpyrrolidone (PVP) is used as a surfactant. PVP can reduce the surface energy of nanoparticles, preventing particle aggregation. It adsorbs onto the surface of nanoparticles, maintaining particle dispersion through steric hindrance. Simultaneously, PVP can also regulate the growth process of the flower-like material, guiding nanoparticles to grow in a specific direction, contributing to the formation of a flower-like morphology. Furthermore, the molecular weight and concentration of PVP have a significant impact on the size and morphology of the flower-like material. Higher molecular weight PVP typically exhibits stronger steric hindrance, better restricting nanoparticle growth and resulting in smaller flower-like material sizes. Appropriate PVP concentration can lead to more elongated petals and better dispersibility in the flower-like material, as it more effectively prevents particle aggregation. Thiourea serves as a sulfur source, providing sulfur ions for the reaction. It can also control the decomposition rate and reactivity, influencing the sulfide formation rate. If the selected sulfur source decomposes too quickly, it may lead to excessively high local sulfur ion concentrations, resulting in uneven growth of the generated sulfide particles. Therefore, this invention selects thiourea as the sulfur source. Additionally, the amount of thiourea affects the amount of sulfide formed. Insufficient thiourea may lead to incomplete sulfidation, resulting in uneven growth of the composite material and affecting its size. An appropriate amount of thiourea ensures uniform sulfide growth, which is beneficial for forming a regular flower-like morphology. The solvent provides the reaction medium, allowing the reactants to mix and contact thoroughly. Meanwhile, the properties of the solvent (such as polarity and boiling point) affect the temperature and pressure of the hydrothermal reaction, and also have a certain impact on the reaction rate and the morphology of the product. For example, high-boiling-point solvents can carry out hydrothermal reactions at higher temperatures, which is beneficial for the crystallization and growth of nanoparticles. Low-viscosity solvents facilitate the diffusion of reactants, which may result in more uniform growth of flower-like materials with relatively smaller sizes. Conversely, high-viscosity solvents may restrict the diffusion of reactants, leading to different local reaction rates and a wider size distribution of the flower-like materials. In this invention, ethylene glycol is chosen as the solvent, which is beneficial for obtaining the morphology of the product of this application.

[0023] The present invention provides a cuprous sulfide / nickel disulfide / carbon composite material, which is prepared by the above method. The cuprous sulfide / nickel disulfide / carbon composite material is a flower-like composite material composed of sheet-like structures, with a cross-shaped structure and a size of 1-3 μm.

[0024] This invention provides the application of a cuprous sulfide / nickel disulfide / carbon composite material in batteries, wherein the cuprous sulfide / nickel disulfide / carbon composite material is used as an active material to prepare a sodium-ion battery anode, thereby preparing a sodium-ion battery.

[0025] Specifically, the cuprous sulfide / nickel disulfide / carbon composite material is the active material. After being mixed evenly with conductive carbon black and PVDF in a ratio of 8:1:1 or 7:2:1, it is magnetically stirred for 6-8 hours to uniformly disperse it in N-methylpyrrolidone (NMP). The uniformly mixed slurry is coated onto copper foil using a coater and placed in a vacuum drying oven at 60-80°C for 12-24 hours. After drying, it is pressed into sheets using a tablet press and then cut into small circular electrode sheets using a cutting machine. The electrode sheets are assembled into button batteries in a glove box filled with high-purity argon gas and with water and oxygen values ​​≤0.01 ppm. The electrolyte is NaCF3SO3+DEGDME. The sodium sheet has a purity of Na≥99.99% and a thickness of 0.5 mm. After rolling, it is cut to the size of the electrode sheet.

[0026] The specific method for assembling the battery is as follows: After adding 1 drop of electrolyte to the positive electrode shell, place the electrode plate, then add 1 drop of electrolyte and place the glass fiber. After adding 3 drops of electrolyte to the glass fiber, place the sodium sheet as the counter electrode, then place two pieces of nickel foam, add 4 drops of electrolyte, cover with the negative electrode shell, press and seal the battery with a hydraulic press, and let it stand for 6 to 12 hours.

[0027] Transition metal chalcogenides (TMCs) are considered excellent anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacity and low manufacturing cost. However, the poor rate performance and cycle performance of TMCs often result in low conductivity during the conversion reaction. This invention addresses this issue by using a flower-like composite material composed of porous nanosheets to improve the electrochemical performance of TMCs. The cuprous sulfide / nickel disulfide / carbon composite material provided by this invention exhibits good cycle stability and high rate performance.

[0028] The flower-like composite material composed of porous cuprous sulfide / nickel disulfide / carbon nanosheets provided by this invention offers sufficient surface area for electrolyte contact and reaction sites during charge and discharge, while also providing more active sites to accommodate volume changes during cycling. This significantly improves cycle stability, lifespan, and battery capacity. Its unique structure allows it to withstand high current and long-term cycling, reducing the loss of active material during charge and discharge and buffering volume changes, thereby improving the electrochemical performance of the negative electrode material. Cu₂S exhibits good conductivity, which is beneficial for sodium formation / desodium formation during the reaction process. Therefore, constructing a Cu₂S / NiS₂ / C porous nanosheet structure is expected to accelerate reaction kinetics. The multi-component synergistic effect of this invention promotes rapid charge transfer, resulting in excellent rate performance and cycle performance. The interfacial effect of the bimetallic sulfide can introduce an internal electric field to improve reaction kinetics, while providing abundant electrochemical reaction sites, thereby improving its reversible capacity and cycle stability.

[0029] This invention develops anode materials with unique structures using a practical and direct SIB method. Microstructured electrode materials are promising candidates (the size range is shown in the SEM images of the products, with 1.5 μm representing a micrometer structure). Micrometer-sized components improve the structural stability of the material. The micrometer structure size allows for better buffering of volumetric strain caused by ion insertion and extraction during charge and discharge. During charge and discharge, sodium ion insertion and extraction cause the material to expand and contract. Micrometer-structured materials can disperse stress, preventing material cracking and pulverization, maintaining electrode structural stability, and ensuring long-term battery cycle performance. Furthermore, micrometer-structured electrode materials form unique interfacial properties when in contact with the electrolyte. Appropriate micrometer size allows for uniform electrolyte wetting of the electrode surface, improving reaction uniformity. Simultaneously, this structure facilitates the formation of a stable SEI film at the electrode / electrolyte interface, preventing electrolyte decomposition and promoting lithium-ion transport, thus improving battery capacity retention and cycle life. Additionally, micrometer-structured electrode materials can promote synergistic effects when combined with other additives and active materials. In composite electrode materials, micron-sized active materials are combined with nano-sized conductive additives (nano-sized conductive carbon black). The former provides channels for electron transport, while the latter fills the spaces between micron-sized particles to reduce overall resistance. The combination significantly improves the capacity, rate performance, and cycle stability of the electrode material, thus benefiting the electrochemical performance of SIBs.

[0030] Compared with existing technologies, the advantages of this invention are that it prepares a flower-like Cu2S / NiS2 / C composite material composed of porous nanosheets through a simple one-step hydrothermal reaction and annealing process, wherein the bimetallic sulfide Cu2S / NiS2 forms a heterojunction with carbon. The heterojunction interface between Cu2S and NiS2 crystals can induce an internal electric field to accelerate ion diffusion kinetics, improve conductivity, and provide abundant reaction sites for sodium energy storage. Furthermore, the carbon matrix shortens the electron / ion path and mitigates strain from volume changes. Benefiting from these advantages, the prepared Cu2S / NiS2 / C composite material exhibits high conductivity at 1 A g / L. -1 After 1000 cycles at current density, the display showed 305 mAh g. -1 The high reversible capacity, high specific capacity, stable cycle performance, and robust rate performance demonstrate that Cu2S / NiS2 / C is an excellent and promising SIB anode material. Furthermore, the copper, nickel, and sulfur sources used in this invention are inexpensive and readily available; carbon doping significantly improves the battery's cycle stability, extends its lifespan, and increases and stabilizes its capacity. Attached Figure Description

[0031] Figure 1 Cu, the precursor precipitate of Example 1 1.81 SEM images of S / NiS2;

[0032] Figure 2 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 1;

[0033] Figure 3 TEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 1;

[0034] Figure 4 HRTEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 1;

[0035] Figure 5 Cu, the precursor prepared in Example 1 1.81 XRD pattern of S / NiS2 precipitate;

[0036] Figure 6 The XRD pattern of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 1;

[0037] Figure 7 Preparation of precursor Cu for Example 2 1.81 SEM image of S / NiS2 precipitate;

[0038] Figure 8SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 2;

[0039] Figure 9 Cu, the precursor prepared in Example 3 1.81 SEM image of S / NiS2 precipitate material;

[0040] Figure 10 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 3;

[0041] Figure 11 Cu, the precursor prepared in Example 4 1.81 SEM image of S / NiS2 precipitate material;

[0042] Figure 12 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 4;

[0043] Figure 13 Cu, the precursor prepared in Example 5 1.81 SEM image of S / NiS2 precipitate material;

[0044] Figure 14 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 5;

[0045] Figure 15 Preparation of precursor Cu for Example 6 1.81 SEM image of S / NiS2 precipitated nanospheres;

[0046] Figure 16 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 6;

[0047] Figure 17 Cu, the precursor prepared in Example 7 1.81 SEM image of S / NiS2 precipitate material;

[0048] Figure 18 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 7;

[0049] Figure 19 Cu precursor prepared in Example 8 1.81 SEM image of S / NiS2 precipitate material;

[0050] Figure 20SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 8;

[0051] Figure 21 Cu precursor prepared in Example 9 1.81 SEM image of the flower-like material of S / NiS2 precipitate;

[0052] Figure 22 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 9;

[0053] Figure 23 Preparation of precursor Cu for Example 10 1.81 SEM image of S / NiS2 precipitate;

[0054] Figure 24 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 10;

[0055] Figure 25 Cu precursor prepared in Example 11 1.81 SEM image of S / NiS2 precipitate material;

[0056] Figure 26 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 11;

[0057] Figure 27 Cu precursor prepared in Example 12 1.81 SEM image of S / NiS2 precipitate material;

[0058] Figure 28 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 12;

[0059] Figure 29 Cu precursor prepared in Example 13 1.81 SEM image of S / NiS2 precipitate material;

[0060] Figure 30 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 13;

[0061] Figure 31 Preparation of precursor Cu for Example 14 1.81 SEM image of S / NiS2 precipitated nanospheres;

[0062] Figure 32SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 14;

[0063] Figure 33 Cu precursor prepared in Example 15 1.81 SEM image of S / NiS2 precipitate material;

[0064] Figure 34 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 15;

[0065] Figure 35 Cu precursor prepared in Example 16 1.81 SEM image of S / NiS2 precipitate material;

[0066] Figure 36 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 16;

[0067] Figure 37 Cu precursor prepared for Example 17 1.81 SEM image of S / NiS2 precipitate material;

[0068] Figure 38 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 17;

[0069] Figure 39 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 18;

[0070] Figure 40 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 19;

[0071] Figure 41 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 20;

[0072] Figure 42 SEM image of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 21;

[0073] Figure 43 The carbon-doped Cu₂S / NiS₂ composite material Cu₂S / NiS₂ / C prepared in Example 1 was used as the anode material for a sodium-ion battery at 0.1 A g. -1 Cyclic stability test results at current density;

[0074] Figure 44 The carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 1 was used as a negative electrode material for a sodium-ion battery at 1 A g. -1 Charge-discharge test diagram at current density;

[0075] Figure 45 Rate capability diagram of the carbon-doped Cu2S / NiS2 composite material Cu2S / NiS2 / C prepared in Example 1 as a sodium-ion battery anode material. Detailed Implementation

[0076] 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 in conjunction with the embodiments of the present invention. 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.

[0077] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0078] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0079] Example 1

[0080] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0081] 1) Preparation of the precursor: Weigh 0.225 g PVP, 0.187 g CuSO4·5H2O, and 0.197 g Ni(NO3)2·6H2O into a 50 mL beaker, add 35 mL of ethylene glycol, and stir magnetically for 10 min to dissolve. Add 0.456 g thiourea and continue stirring magnetically for 10 min. Transfer the mixture to a 50 mL polytetrafluoroethylene reactor and react at 160 °C for 2.5 h. After naturally cooling to room temperature, wash four times with deionized H2O by centrifugation, wash twice with ethanol, and vacuum dry at 60 °C for 12 h. Collect the precursor Cu. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 1 As shown in the figure, it can be seen that it has a micro-flower-like structure with a size of 1-3 μm. The prepared Cu... 1.81 XRD pattern of S / NiS2 precursor material as shown in Figure Figure 6 As shown.

[0082] 2) Preparation of Cu2S / NiS2 / C:

[0083] The dried precursor product was placed in a ceramic boat and calcined in an argon atmosphere at a heating rate of 2℃ / min until the calcination temperature reached 400℃. The calcination time was 2 hours, yielding the final product Cu2S / NiS2 / C. Its SEM image is shown below. Figure 2 As shown in the image, it can be seen that it has a flower-like structure composed of sheet-like structures. TEM image as follows. Figure 3 As shown.

[0084] The HRTEM of the Cu2S / NiS2 / C composite material obtained in this embodiment is as follows: Figure 4 As shown, the obtained product is a complex of Cu2S and NiS2, and the XRD pattern is as follows. Figure 6 As shown, the obtained product is Cu2S / NiS2 / C.

[0085] Example 2 (as a comparison)

[0086] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0087] 1) Preparation of precursors: Weigh 0.225g PVP, 0.187g CuSO4·5H2O, and 0.197g Ni(NO3)2·6H2O into a 50mL beaker, add 35mL ethylene glycol, and stir magnetically for 10min to dissolve. Add 0.456g thiourea and continue stirring magnetically for 10min. Transfer the mixture to a 50mL polytetrafluoroethylene reactor and place it in an oven. 120℃ The reaction proceeded for 2.5 h. After natural cooling to room temperature, the product was washed four times by centrifugation with deionized H₂O, twice by washing with ethanol, and then vacuum dried at 60 °C for 12 h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 7 As shown in the image, the shape has changed and is no longer flower-like.

[0088] 2) Preparation of Cu2S / NiS2 / C:

[0089] The dried precursor product was placed in a ceramic boat and calcined in an argon atmosphere at a heating rate of 2℃ / min until the calcination temperature reached 400℃. The calcination time was 2 hours, yielding the final product Cu2S / NiS2 / C. Its SEM image is shown below. Figure 8 As shown in the figure, it remains consistent with the structure before calcination, exhibiting a strip-like structure.

[0090] Example 3 (as a comparison)

[0091] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0092] 1) Preparation of precursors: Weigh 0.225g PVP, 0.187g CuSO4·5H2O, and 0.197g Ni(NO3)2·6H2O into a 50mL beaker, add 35mL ethylene glycol, and stir magnetically for 10min to dissolve. Add 0.456g thiourea and continue stirring magnetically for 10min. Transfer the mixture to a 50mL polytetrafluoroethylene reactor and place it in an oven. 140℃ The reaction proceeded for 2.5 h. After natural cooling to room temperature, the product was washed four times by centrifugation with deionized H₂O, twice by washing with ethanol, and then vacuum dried at 60 °C for 12 h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 9 As shown in the figure, it can be seen that it has a micro-flower-like and erythrocyte-like structure with an uneven morphology and a size of 1-3 μm.

[0093] 2) Preparation of Cu2S / NiS2 / C:

[0094] The dried precursor product was placed in a ceramic boat and calcined in an argon atmosphere at a heating rate of 2℃ / min until the calcination temperature reached 400℃. The calcination time was 2 hours, yielding the final product Cu2S / NiS2 / C. Its SEM image is shown below. Figure 10 As shown in the figure, it is consistent with the state before calcination.

[0095] Example 4 (as a comparison)

[0096] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0097] 1) Preparation of precursors: Weigh 0.225g PVP, 0.187g CuSO4·5H2O, and 0.197g Ni(NO3)2·6H2O into a 50mL beaker, add 35mL ethylene glycol, and stir magnetically for 10min to dissolve. Add 0.456g thiourea and continue stirring magnetically for 10min. Transfer the mixture to a 50mL polytetrafluoroethylene reactor and place it in an oven. 180℃ The reaction proceeded for 2.5 h. After natural cooling to room temperature, the product was washed four times by centrifugation with deionized H₂O, twice by washing with ethanol, and then vacuum dried at 60 °C for 12 h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 11 As shown in the figure, it can be seen that it has micro-flower-like, cubic and red blood cell-like structures, with a size of 1-3 μm.

[0098] 2) Preparation of Cu2S / NiS2 / C:

[0099] The dried precursor product was placed in a ceramic boat and calcined in an argon atmosphere at a heating rate of 2℃ / min until the calcination temperature reached 400℃. The calcination time was 2 hours, yielding the final product Cu2S / NiS2 / C. Its SEM image is shown below. Figure 12 As shown in the figure, it is consistent with the precursor structure.

[0100] Example 5 (as a comparison)

[0101] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0102] 1) Preparation of precursors: Weigh 0.225g PVP, 0.187g CuSO4·5H2O, and 0.197g Ni(NO3)2·6H2O into a 50mL beaker, add 35mL ethylene glycol, and stir magnetically for 10min to dissolve. Add 0.456g thiourea and continue stirring magnetically for 10min. Transfer the mixture to a 50mL polytetrafluoroethylene reactor and place it in an oven. 200℃ The reaction proceeded for 2.5 h. After natural cooling to room temperature, the product was washed four times by centrifugation with deionized H₂O, twice by washing with ethanol, and then vacuum dried at 60 °C for 12 h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 13 As shown in the figure, it has a sheet-like structure, but the flower-like structure is not very obvious, and the size is 1-3 μm.

[0103] 2) Preparation of Cu2S / NiS2 / C:

[0104] The dried precursor product was placed in a ceramic boat and calcined in an argon atmosphere at a heating rate of 2℃ / min until the calcination temperature reached 400℃. The calcination time was 2 hours, yielding the final product Cu2S / NiS2 / C. Its SEM image is shown below. Figure 14 As shown in the figure, it can be seen that it is consistent with the precursor.

[0105] Example 6

[0106] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0107] 1) Preparation of the precursor: Weigh 0.225 g PVP, 0.187 g CuSO4·5H2O, and 0.394 g Ni(NO3)2·6H2O into a 50 mL beaker, add 35 mL of ethylene glycol, and stir magnetically for 10 min to dissolve. Add 0.456 g thiourea and continue stirring magnetically for 10 min. Transfer the mixture to a 50 mL polytetrafluoroethylene reactor and react at 160 °C for 2.5 h. After naturally cooling to room temperature, wash four times with deionized H2O by centrifugation, wash twice with ethanol, and vacuum dry at 60 °C for 12 h. Collect the precursor Cu. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 15 As shown in the figure, it can be seen that it has a sheet-like structure, some flower-like structures, and most of it is irregular, with a size of 1-3 μm.

[0108] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 16 As shown in the figure, the morphology is consistent with that of the precursor.

[0109] Example 7

[0110] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0111] 1) Preparation of the precursor: Weigh 0.225 g PVP, 0.187 g CuSO4·5H2O, and 0.591 g Ni(NO3)2·6H2O into a 50 mL beaker. Add 35 mL of ethylene glycol and stir magnetically for 10 min to dissolve. Add 0.456 g thiourea and continue stirring magnetically for 10 min. Transfer the mixture to a 50 mL polytetrafluoroethylene reactor and react at 160 °C for 2.5 h. Allow to cool naturally to room temperature. Wash four times with deionized H2O by centrifugation and twice with ethanol. Dry under vacuum at 60 °C for 12 h. Collect the precursor Cu. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 17 As shown in the figure, it can be seen that it is a flower-like structure composed of nanosheets, but the yield is relatively small and the size is 1-3 μm.

[0112] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 18 As shown in the figure, the morphology is consistent with that of the precursor.

[0113] Example 8 (as a comparison)

[0114] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0115] 1) Preparation of precursors: Weigh 0.225g PVP and 0.187g CuSO4·5H2O respectively. 0.788g Ni(NO3)2·6H2O was placed in a 50 mL beaker, and 35 mL of ethylene glycol was added. The mixture was magnetically stirred for 10 min to dissolve. Then, 0.456 g of thiourea was added, and the mixture was magnetically stirred for another 10 min. The mixture was then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After naturally cooling to room temperature, the mixture was washed four times with deionized H2O by centrifugation, twice with ethanol, and vacuum dried at 60 °C for 12 h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 19 As shown in the figure, it can be seen that it has flower-like and block-like structures with uneven morphology. Most of the flower-like materials are 1-3 μm in size.

[0116] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 20 As shown in the figure, the morphology is consistent with that of the precursor.

[0117] Example 9 (as a comparison)

[0118] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0119] 1) Preparation of precursors: Weigh 0.225g PVP and 0.187g CuSO4·5H2O respectively. 0.985g Ni(NO3)2·6H2O was placed in a 50 mL beaker, and 35 mL of ethylene glycol was added. The mixture was magnetically stirred for 10 min to dissolve. Then, 0.456 g of thiourea was added, and the mixture was magnetically stirred for another 10 min. The mixture was then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After naturally cooling to room temperature, the mixture was washed four times with deionized H2O by centrifugation, twice with ethanol, and vacuum dried at 60 °C for 12 h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 21 As shown in the figure, it can be seen that it has a blocky structure.

[0120] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 22 As shown in the figure, the morphology is consistent with that of the precursor.

[0121] By comparison Figure 1 and Figures 17-22 As can be seen, with the increase of the ratio between nickel and copper sources, sulfides are more likely to aggregate during the hydrothermal process. Furthermore, the nickel source tends to form individual sulfides, leading to unsuccessful recombination. Morphologically, this results in heterogeneity and a tendency to form blocky structures that agglomerate together.

[0122] Example 10 (as a comparison)

[0123] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0124] 1) Preparation of precursors: Weigh out the following: 0.45g 0.187g CuSO4·5H2O and 0.197g Ni(NO3)2·6H2O were placed in a 50mL beaker, and 35mL of ethylene glycol was added. The mixture was magnetically stirred for 10min to dissolve the compounds. Then, 0.456g thiourea was added, and the mixture was magnetically stirred for another 10min. The mixture was then transferred to a 50mL polytetrafluoroethylene (PTFE) reactor and reacted in an oven at 160℃ for 2.5h. After naturally cooling to room temperature, the mixture was washed four times with deionized H2O by centrifugation, twice with ethanol, and vacuum dried at 60℃ for 12h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 23 As shown in the figure, it has a sheet-like structure with many irregular fragments.

[0125] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 24 As shown in the figure, the morphology is consistent with that of the precursor.

[0126] Example 11 (as a comparison)

[0127] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0128] 1) Preparation of precursors: Weigh out the following: 0.675g 0.187g CuSO4·5H2O and 0.197g Ni(NO3)2·6H2O were placed in a 50mL beaker, and 35mL of ethylene glycol was added. The mixture was magnetically stirred for 10min to dissolve the compounds. Then, 0.456g thiourea was added, and the mixture was magnetically stirred for another 10min. The mixture was then transferred to a 50mL polytetrafluoroethylene (PTFE) reactor and reacted in an oven at 160℃ for 2.5h. After naturally cooling to room temperature, the mixture was washed four times with deionized H2O by centrifugation, twice with ethanol, and vacuum dried at 60℃ for 12h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 25 As shown in the figure, a small part of it consists of circular flower-like structures composed of sheets, while the rest are irregular sheet-like structures.

[0129] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 26 As shown in the figure, the morphology is consistent with that of the precursor.

[0130] Example 12 (as a comparison)

[0131] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0132] 1) Preparation of precursors: Weigh out the following: 0.9g 0.187g CuSO4·5H2O and 0.197g Ni(NO3)2·6H2O were placed in a 50mL beaker, and 35mL of ethylene glycol was added. The mixture was magnetically stirred for 10min to dissolve the compounds. Then, 0.456g thiourea was added, and the mixture was magnetically stirred for another 10min. The mixture was then transferred to a 50mL polytetrafluoroethylene (PTFE) reactor and reacted in an oven at 160℃ for 2.5h. After naturally cooling to room temperature, the mixture was washed four times with deionized H2O by centrifugation, twice with ethanol, and vacuum dried at 60℃ for 12h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 27 As shown in the figure, it can be seen that it has a disc-like structure and a block-like structure. The two morphologies are not uniform, and the size of most disc-like structure materials is 1-3μm.

[0133] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 28 As shown in the figure, the morphology is consistent with that of the precursor.

[0134] Example 13 (as a comparison)

[0135] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0136] 1) Preparation of precursors: Weigh out the following: 1.125 0.187g PVP, 0.187g CuSO4·5H2O, and 0.197g Ni(NO3)2·6H2O were placed in a 50mL beaker, and 35mL of ethylene glycol was added. The mixture was magnetically stirred for 10min to dissolve the PVP. Then, 0.456g thiourea was added, and the mixture was magnetically stirred for another 10min. The mixture was then transferred to a 50mL polytetrafluoroethylene (PTFE) reactor and reacted at 160℃ for 2.5h. After naturally cooling to room temperature, the mixture was washed four times with deionized H2O by centrifugation, twice with ethanol, and vacuum dried at 60℃ for 12h. The precursor Cu was collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 29 As shown in the figure, it can be seen that it is a mixture of three structures: a pancake-like structure, a flower-like structure, and a block-like structure, with the majority being a block-like structure composed of pancakes.

[0137] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 30 As shown in the figure, the morphology is consistent with that of the precursor.

[0138] By comparison Figure 1 and Figures 23-30 As can be seen, with the increase of PVP, sulfides are more likely to aggregate together during the hydrothermal process, and the flower-like structure composed of nanosheets transitions to the appearance of a cake-like structure, and finally to a spherical structure, easily forming a mixture of various morphologies.

[0139] Example 14 (as a comparison)

[0140] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0141] 1) Preparation of precursors: Weigh 0.225g PVP, 0.187g CuSO4·5H2O, and 0.197g Ni(NO3)2·6H2O into a 50mL beaker, add 35mL ethylene glycol, stir magnetically for 10min to dissolve, and then add... 0.912g After further magnetic stirring for 10 min, the thiourea was transferred to a 50 mL polytetrafluoroethylene (PTFE) reactor and placed in an oven at 160 °C for 2.5 h. After natural cooling to room temperature, the product was washed four times with deionized H₂O by centrifugation, twice with ethanol, and vacuum dried at 60 °C for 12 h. The precursor precipitate was collected. Its SEM image is shown below. Figure 31 As shown in the figure, it can be seen that it has a spherical structure, but most of it is stuck together, irregular, and the size is 1-3μm.

[0142] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 32 As shown in the figure, the morphology is consistent with that of the precursor.

[0143] Example 15 (as a comparison)

[0144] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0145] 1) Preparation of precursors: Weigh 0.225g PVP, 0.187g CuSO4·5H2O, and 0.197g Ni(NO3)2·6H2O into a 50mL beaker, add 35mL ethylene glycol, stir magnetically for 10min to dissolve, and then add... 1.368 After stirring thiourea for 10 min, the mixture was transferred to a 50 mL polytetrafluoroethylene (PTFE) reactor and reacted in an oven at 160 °C for 2.5 h. After natural cooling to room temperature, the product was washed four times with deionized H₂O by centrifugation, twice with ethanol, and vacuum dried at 60 °C for 12 h. The precursor precipitate was collected. Its SEM image is shown below. Figure 33 As shown in the figure, it can be seen that it consists of small spherical particles mixed with larger spherical and rod-shaped structures, but the yield is relatively low.

[0146] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 34 As shown in the figure, the morphology is consistent with that of the precursor.

[0147] Example 16 (as a comparison)

[0148] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0149] 1) Preparation of precursors: Weigh 0.225g PVP, 0.187g CuSO4·5H2O, and 0.197g Ni(NO3)2·6H2O into a 50mL beaker, add 35mL ethylene glycol, stir magnetically for 10min to dissolve, and then add... 1.824 After stirring thiourea magnetically for 10 min, the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After naturally cooling to room temperature, the mixture was washed four times with deionized H₂O by centrifugation, twice with ethanol, and vacuum dried at 60 °C for 12 h. The precursor Cu was then collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 35 As shown in the figure, it can be seen that it is a blocky structure that is stuck together and has an uneven shape.

[0150] 2) The preparation of Cu2S / NiS2 / C is the same as in Example 1, and its SEM image is shown below. Figure 36 As shown in the figure, the morphology is consistent with that of the precursor.

[0151] Example 17 (as a comparison)

[0152] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0153] 1) Preparation of precursors: Weigh 0.225g PVP, 0.187g CuSO4·5H2O, and 0.197g Ni(NO3)2·6H2O into a 50mL beaker, add 35mL ethylene glycol, stir magnetically for 10min to dissolve, and then add... 2.28g After further magnetic stirring for 10 min, the thiourea was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After natural cooling to room temperature, the mixture was washed four times with deionized H₂O by centrifugation, twice with ethanol, and vacuum dried at 60 °C for 12 h. The precursor Cu was then collected. 1.81 S / NiS2 precipitate. Its SEM image is shown below. Figure 37 As shown in the figure, it can be seen that it is a clustered blocky structure, with most of the components measuring 1-3 μm in size.

[0154] 2) The preparation of Cu2S / NiS2 / C was the same as in Example 1, and the SEM image of the product is shown below. Figure 38 As shown in the figure, the morphology is consistent with that of the precursor.

[0155] By comparison Figure 1 and Figures 31-38 It can be seen that as the amount of sulfur source increases, the sulfides are more likely to stick together during the hydrothermal process, and instead of forming a flower-like structure of nanosheets, they form a spherical structure. The size of the spheres varies, and the larger the amount of sulfur source used, the larger the size and the more uniform the morphology of the spheres.

[0156] Example 18

[0157] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0158] 1) The preparation of the precursor is the same as in Example 1;

[0159] 2) Preparation of Cu2S / NiS2 / C:

[0160] The dried precursor product was placed in a ceramic boat and calcined in an argon atmosphere at a heating rate of 2℃ / min until the calcination temperature reached 300℃. The calcination time was 2 hours, yielding the final product Cu2S / NiS2 / C. Its SEM image is shown below. Figure 39 As shown in the figure, it can be seen that it is a flower-like structure composed of nanosheets.

[0161] Example 19 (as a comparison)

[0162] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0163] 1) The preparation of the precursor is the same as in Example 1;

[0164] 2) Preparation of Cu2S / NiS2 / C:

[0165] The dried precursor product was placed in a porcelain boat and calcined in an argon atmosphere at a heating rate of 2℃ / min until the calcination temperature was reached. 500℃ The calcination time was 2 hours, and the final product Cu2S / NiS2 / C was obtained. Its SEM image is shown below. Figure 40 As shown in the image, the flower-like structure collapsed, leaving only fragments.

[0166] Example 20 (as a comparison)

[0167] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0168] 1) The preparation of the precursor is the same as in Example 1;

[0169] 2) Preparation of Cu2S / NiS2 / C:

[0170] The dried precursor product was placed in a porcelain boat and calcined in an argon atmosphere at a heating rate of 2℃ / min until the calcination temperature was reached. 600℃ The calcination time was 2 hours, and the final product Cu2S / NiS2 / C was obtained. Its SEM image is shown below. Figure 41 As shown in the figure, its structure has been completely changed, and it has an irregular shape.

[0171] Example 21 (for comparison)

[0172] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material includes the following steps:

[0173] 1) The preparation of the precursor is the same as in Example 1;

[0174] 2) Preparation of Cu2S / NiS2 / C:

[0175] The dried precursor product was placed in a porcelain boat and calcined in a flowing argon atmosphere at a temperature of [temperature missing]. 700℃ The calcination time was 2 hours, and the heating rate was 2℃ / min. The final product Cu2S / NiS2 / C was obtained, and its SEM image is shown below. Figure 42 As shown in the figure, its morphology is completely different from that of Example 1, and it has a blocky structure.

[0176] Performance testing:

[0177] The product of Example 1 was used to prepare sodium batteries as anode materials for sodium-ion batteries, specifically:

[0178] The active material, cuprous sulfide / nickel disulfide / carbon composite, is mixed with conductive carbon black and PVDF in a ratio of 7:2:1. After uniform mixing, it is magnetically stirred for 8 hours to disperse it evenly in NMP. The uniformly mixed slurry is coated onto copper foil using a coater and placed in a vacuum drying oven at 80°C for 24 hours. After drying, it is pressed into sheets using a tablet press and then cut into small circular electrode sheets using a cutting machine. The electrode sheets are assembled into button batteries in a glove box filled with high-purity argon gas and with water and oxygen values ​​≤0.01ppm. The electrolyte is NaCF3SO3+DEGDME. The sodium sheet has a purity of Na≥99.99% and a thickness of 0.5mm. After rolling, it is cut to the size of the electrode sheet.

[0179] The specific method for assembling the battery is as follows: Add one drop of electrolyte to the positive electrode shell, then place the electrode plate. Next, add one drop of electrolyte and place the glass fiber. Add three drops of electrolyte to the glass fiber and place a sodium sheet as the counter electrode. Then, place two pieces of nickel foam, add four more drops of electrolyte, cover with the negative electrode shell, and use a hydraulic press to press and seal the battery. Let it stand for 12 hours.

[0180] Specific testing procedure: After assembling the sodium-ion half-cell, the following steps were set on the Xinwei tester: first, constant current discharge to 0.1V, then constant current charging to 3V, repeating this cycle a certain number of times. The active material loading on the electrode plates was approximately 1.0 mg / cm³. -2 .

[0181] The test results and data are as follows:

[0182] Figure 43 The carbon-doped flower-like Cu₂S / NiS₂ composite material (Cu₂S / NiS₂ / C) prepared in Example 1 is shown to be used as a sodium-ion battery anode material in 0.1 A g⁻¹. -1 Cyclic stability test results at current density; the circuit can cycle stably for more than 100 cycles at this current density, demonstrating good cyclic stability.

[0183] Figure 44 The current density is 1A g -1 The charge-discharge curves show an average discharge voltage of around 1.8V. The second and third curves have a high degree of overlap, indicating good reversibility.

[0184] Figure 45 The graph shows the rate capability of the carbon-doped Cu2S / NiS2 composite material (Cu2S / NiS2 / C) prepared in Example 1 as a negative electrode material for a sodium-ion battery. As can be seen from the graph, this composite material exhibits good rate performance. Furthermore, it still maintains high capacity after two cycles of high-current rate cycling, indicating good electrochemical performance.

[0185] The data underlined above do not meet the requirements of this invention.

[0186] The above description of the embodiments is intended to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material, characterized in that, The preparation method includes the following steps: 1) Preparation of Cu by hydrothermal reaction 1.81 S / NiS2 flower-like material; 2) Cu 1.81 The S / NiS2 flower-like material was annealed under a protective atmosphere to obtain a Cu2S / NiS2 / C composite material; Step 1) Preparation method: Disperse copper source, nickel source, polyvinylpyrrolidone and sulfur source in solvent, and perform hydrothermal reaction to obtain Cu. 1.81 S / NiS2 flower-like material; In step 1), the molar ratio of polyvinylpyrrolidone, copper source, nickel source and sulfur source is 0.03:0.75:0.65-2.25:6; The solvent is ethylene glycol; the sulfur source is thiourea; the polyvinylpyrrolidone is PVP, K16-18, with a molecular weight M=8000; the hydrothermal reaction is carried out at 160℃ for 2-3 hours; in step 2), the annealing refers to annealing at 300-400℃ for 2 hours.

2. A cuprous sulfide / nickel disulfide / carbon composite material prepared by the method of claim 1, characterized in that, The cuprous sulfide / nickel disulfide / carbon composite material has a flower-like structure composed of nanosheets, which is a cross-shaped structure with a size of 1-3 μm.

3. The application of the cuprous sulfide / nickel disulfide / carbon composite material as described in claim 2 in a battery, characterized in that, Used to prepare the negative electrode for sodium-ion batteries.

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