Cuprous sulfide / nickel disulfide / carbon composite material, preparation method thereof and application of cuprous sulfide / nickel disulfide / carbon composite material in battery

Abstract

The invention provides a cuprous sulfide / nickel disulfide / carbon composite material as well as a preparation method and application thereof in a battery, and the preparation method comprises the following steps: dispersing a copper source, a nickel source, polyvinylpyrrolidone and a sulfur source in a solvent, carrying out hydrothermal reaction to obtain a Cu1.81 S / NiS2 flower-like material, and annealing to obtain the cuprous sulfide / nickel disulfide / carbon composite material. Compared with the prior art, the Cu2S / NiS2 / C nanosphere composite material is prepared through a simple hydrothermal reaction and an annealing process. A heterogeneous interface between Cu2S and NiS2 crystals can induce an internal electric field to accelerate ion diffusion kinetics, improve conductivity and provide rich reaction sites for sodium energy storage. The material has the advantages of high reversible capacity, high specific capacity, stable cycle performance and steady rate capability.

Description

Technical Field

[0001] The present invention belongs to the field of sodium ion battery material preparation, and specifically relates to a cuprous sulfide / nickel disulfide / carbon composite material and a preparation method thereof and application in batteries. 2 S / NiS 2 / C is used as a negative electrode material for sodium ion batteries to make sodium ion batteries. Background Art

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

[0003] As a potential energy storage technology, sodium-ion batteries have attracted much attention in recent years. Sodium is abundant, widely distributed and low-cost on Earth, and has obvious resource advantages over lithium. In addition, the working principle of sodium-ion batteries is similar to that of lithium-ion batteries, and to a certain extent, they can draw on the mature technology and production experience of lithium-ion batteries.

[0004] However, sodium-ion batteries still face some challenges in terms of performance. For example, the ionic radius of sodium ions is larger than that of lithium ions, which may lead to poor structural stability of electrode materials during the charge and discharge process, affecting the cycle life of the battery. At the same time, the energy density of sodium-ion batteries is relatively low, which limits their application in certain fields with high energy density requirements. In order to overcome these challenges, researchers are committed to developing new electrode materials, optimizing battery structures, and improving manufacturing processes to improve the performance of sodium-ion batteries so that they can better meet the application needs of different fields.

[0005] Therefore, it is necessary to provide a new material for sodium ion batteries to improve their performance. Summary of the invention

[0006] The present invention aims to provide a cuprous sulfide / nickel disulfide / carbon composite material and a preparation method thereof, and to prepare a flower-shaped Cu nanosheet composed of porous nanosheets by a simple one-step hydrothermal reaction and annealing process. 2 S / NiS 2 / C composites, in which bimetallic sulfide Cu 2 S / NiS 2 It forms a heterojunction with carbon; it can be used in sodium-ion batteries to improve performance.

[0007] Another object of the present invention is to provide an application of a cuprous sulfide / nickel disulfide / carbon composite material in a battery, using the cuprous sulfide / nickel disulfide / carbon composite material as an active material to prepare a sodium ion battery negative electrode, and then to prepare a sodium ion battery, thereby greatly improving the life, cycle stability and battery capacity of the sodium ion battery.

[0008] The specific technical solutions of the present invention are as follows:

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

[0010] 1) Preparation of Cu by hydrothermal reaction 1.81 S / NiS 2 Flower-like materials;

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

[0012] Step 1) The preparation method is: disperse the copper source, nickel source, polyvinyl pyrrolidone and sulfur source in a solvent, and perform hydrothermal reaction to obtain Cu 1.81 S / NiS 2 Flower-like material.

[0013] In step 1), the molar ratio of polyvinyl pyrrolidone, 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 amount ratio of the copper source to the solvent is 0.02-0.05 mmol / mL; the copper source is a soluble copper source, preferably CuSO 4 ·5H 2 O; the nickel source is a soluble copper source, preferably NiSO 4 6H 2 O.Ni(NO 3 ) 2 6H 2 O; the solvent is ethylene glycol, the sulfur source is a soluble sulfur source, preferably thiourea; the polyvinyl pyrrolidone is PVP, K16-18, with a molecular weight of M=8000;

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

[0015] In step 1), after the hydrothermal reaction, washing is performed, washing with water 4 to 6 times, washing with ethanol 1 to 2 times, centrifuging, and drying; wherein the drying temperature is 40 to 80° C., and the time is 12 to 15 hours;

[0016] The Cu prepared in step 1) 1.81 S / NiS 2 Flower-like materials are formed by cross-stacked nanosheets in a flower shape with a size of 1-3μm.

[0017] In step 2), the annealing refers to annealing at 300-400°C for 2h, preferably at 400°C;

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

[0019] In step 2), the temperature is raised to 300-400°C at a heating rate of 2°C / min for annealing and calcining; preferably, the annealing and calcining is carried out in a tubular furnace;

[0020] In the preparation of the present invention: under hydrothermal conditions, the solvent provides a high temperature and high pressure reaction environment. The copper source and the nickel source will dissolve in the solvent, releasing copper ions and nickel ions. Polyvinylpyrrolidone (PVP) as a surfactant and stabilizer can be adsorbed on the surface of the nanoparticles being formed. Thiourea will decompose in the reaction system to produce sulfide ions, which react with copper ions and nickel ions to generate copper sulfide (Cu 2 S) and nickel sulfide (NiS 2 ) precursor, namely Cu 1.81 S / NiS 2 These precursors gradually grow and aggregate in a hydrothermal environment, and eventually form a flower-like morphology due to factors such as anisotropic growth.

[0021] The annealing and calcining process is mainly to heat treat the precursor. During high temperature calcination, the components in the precursor will undergo further reactions and phase changes. For example, copper sulfide (CuS) will partially transform into Cu 2 S, nickel sulfide (NiS) will be converted into NiS 2 At the same time, organic matter such as PVP will decompose to produce carbon (C), thereby obtaining Cu 2 S / NiS 2 / C composite materials. In this process, the crystallinity of the material will be improved and the internal structure will be more stable.

[0022] Among the raw materials used, copper source and nickel source are the metal ion sources for synthesizing copper sulfide and nickel sulfide. Their types (such as different copper salts and nickel salts) and concentrations will affect the content of copper and nickel in the final product, and thus affect the performance of the material. For example, if the copper source concentration is relatively high, the Cu in the final product will be 2The proportion of S may increase. Increasing the concentration of the copper source or nickel source may cause the size of the flower-like material to become larger. This is because the increase in the concentration of metal ions provides more raw materials for the growth of sulfides, making the particles grow faster and larger. At the same time, the ratio of the copper source to the nickel source will also affect the morphology of the composite material. If the proportion of the nickel source increases, the petal shape or branch structure of the flower-like material may be changed. Therefore, the present invention needs to control the appropriate nickel source and copper source dosage ratio. The polyvinyl pyrrolidone (PVP) used is used as a surfactant. PVP can reduce the surface energy of nanoparticles and prevent particle agglomeration. It is adsorbed on the surface of the nanoparticles and keeps the particles in a dispersed state through the steric hindrance effect. At the same time, PVP can also regulate the growth process of the flower-like material, guide the nanoparticles to grow in a certain direction, and help to form a flower-like morphology. In addition, the molecular weight and concentration of PVP have an important influence on the size and morphology of the flower-like material. PVP with a higher molecular weight usually has a stronger steric hindrance effect, which can better limit the growth of nanoparticles and reduce the size of the flower-like material. The appropriate addition of PVP concentration can make the petals of the flower-like material more slender and more dispersed because it can more effectively prevent particle agglomeration. Thiourea is a sulfur source, providing sulfur ions for the reaction. It can control the decomposition rate and reaction activity, and affect the generation rate of sulfide. If the selected sulfur source decomposes too quickly, it may cause the local sulfur ion concentration to be too high, causing the generated sulfide particles to grow unevenly. Therefore, the present invention selects thiourea as a sulfur source. In addition, the amount of thiourea used will affect the amount of sulfide generated. If the amount of thiourea used is insufficient, it may cause incomplete vulcanization, causing uneven growth of the composite material and affecting the size. An appropriate amount of thiourea can ensure the uniform growth of sulfide and is conducive to the formation of a regular flower-like morphology. The solvent provides a medium for the reaction so that the reactants can be fully mixed and contacted. At the same time, the properties of the solvent (such as polarity, boiling point, etc.) will affect the temperature and pressure of the hydrothermal reaction, and also have a certain effect on the reaction rate and the morphology of the product. For example, a solvent with a high boiling point can carry out a hydrothermal reaction at a higher temperature, which is conducive to the crystal growth of nanoparticles. A low-viscosity solvent is conducive to the diffusion of the reactants, which may make the growth of the flower-like material more uniform and relatively small in size. A high-viscosity solvent may limit the diffusion of the reactants, resulting in different local reaction rates and a wider size distribution of the flower-like material. The present invention selects ethylene glycol as the solvent, which is beneficial to obtaining the morphology of the product of the present 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-shaped composite material composed of a sheet structure, a cross structure, and a size of 1-3 μm.

[0024] The present invention provides an application of a cuprous sulfide / nickel disulfide / carbon composite material in a battery. The cuprous sulfide / nickel disulfide / carbon composite material is used as an active material to prepare a negative electrode of a sodium ion battery, thereby preparing a sodium ion battery.

[0025] Specifically, the cuprous sulfide / nickel disulfide / carbon composite material is an active material, which is uniformly mixed with conductive carbon black and PVDF in a ratio of 8:1:1 or 7:2:1, and then uniformly dispersed in N-methylpyrrolidone (NMP) by magnetic stirring for 6 to 8 hours, and the uniformly mixed slurry is coated on a copper foil by a coater, and placed in a vacuum drying oven at 60 to 80° C., and after drying for 12 to 24 hours, it is pressed by a tablet press, and then cut into a small circular electrode sheet by a sheet cutter; the prepared electrode sheet is assembled into a button battery in a glove box filled with high-purity argon and the water oxygen value is ≤0.01ppm; the electrolyte is NaCF 3 SO 3 +DEGDME, the purity of the sodium sheet is Na≥99.99%, the thickness is 0.5mm, and it is cut into the size of the electrode sheet after rolling.

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

[0027] Transition metal sulfide is considered to be an excellent negative electrode material for sodium ion battery (SIB) due to its high theoretical specific capacity and low manufacturing cost. However, the poor rate performance and cycle performance of transition metal sulfide always lead to low conductivity during the conversion reaction. The present invention improves the electrochemical performance of transition metal sulfide by using a flower-like composite material composed of porous nanosheets. The cuprous sulfide / nickel disulfide / carbon composite material provided by the present invention has good cycle stability and high rate performance.

[0028] The flower-shaped composite material composed of cuprous sulfide / nickel disulfide / carbon porous nanosheets provided by the present invention provides sufficient surface area for electrolyte contact and reaction sites during the charge and discharge process, and also provides more active sites to adapt to the volume change during the cycle process, greatly improving the cycle stability, service life and battery capacity. Its unique structure enables it to withstand high current and long cycles, reduces the loss of active substances during the charge and discharge process, and buffers the volume change during the charge and discharge process, thereby improving the electrochemical performance of the negative electrode material. 2 S has good conductivity, which is beneficial to the sodiumation / de-sodiumation process. 2 S / NiS 2The C / C porous nanosheet structure is expected to accelerate the reaction kinetics. The multi-component synergistic effect of the present invention promotes the rapid transfer of charge, resulting in excellent rate performance and cycle performance. The interface effect of the bimetallic sulfide can introduce an internal electric field to improve the reaction kinetics, while providing abundant electrochemical reaction sites, thereby improving its reversible capacity and cycle stability.

[0029] The present invention develops negative electrode materials with unique structures through a practical and direct SIB method. Electrode materials with microstructures are promising candidate materials (the size range can be seen from the SEM image of the product of the present invention, and 1.5μm is a micron structure). Micron-sized components can improve the structural stability of the material. The micron-sized structure enables it to better buffer the volume strain caused by ion embedding and extraction during charging and discharging. The embedding and extraction of sodium ions during charging and discharging causes the volume of the material to expand and shrink. Micron-structured materials can disperse stress, avoid material rupture and pulverization, maintain the stability of the electrode structure, and ensure the long-term cycle performance of the battery. In addition, when the micron-structured electrode material contacts the electrolyte, unique interface characteristics will be formed. The appropriate micron size can make the electrolyte evenly infiltrate the electrode surface and improve the uniformity of the reaction. At the same time, this structure helps to form a stable SEI film at the electrode / electrolyte interface, which can not only prevent the decomposition of the electrolyte, but also promote lithium ion transmission, thereby improving the battery capacity retention rate and cycle life. At the same time, when the micron-structured electrode material is compounded with other additives and active substances, it can promote the synergy of different components. For example, in composite electrodes, micron-sized active materials are compounded with nano-sized conductive additives (nano-sized conductive carbon black). The former provides a channel for electron transmission, and the latter fills between micron particles to reduce the overall resistance. The combination of the two significantly improves the capacity, rate performance and cycle stability of electrode materials, which is beneficial to the electrochemical performance of SIBs.

[0030] Compared with the prior art, the present invention has the advantage of preparing a flower-shaped Cu composed of porous nanosheets through a simple one-step hydrothermal reaction and annealing process. 2 S / NiS 2 / C composites, in which bimetallic sulfide Cu 2 S / NiS 2 It forms a heterojunction with carbon. Cu 2 S and NiS 2 The heterogeneous interface between crystals can induce an internal electric field to accelerate ion diffusion kinetics, improve conductivity and provide abundant reaction sites for sodium energy storage. In addition, the carbon matrix shortens the path of electrons / ions and alleviates the strain of volume change. Benefiting from these advantages, the prepared Cu 2 S / NiS 2 / C composites at 1A g -1 After 1000 cycles at the same current density, the current density was 305 mAh g -1The high reversible capacity, high specific capacity, stable cycling performance and robust rate performance indicate that Cu 2 S / NiS 2 / C is an excellent and promising SIB negative electrode material. Moreover, the copper source, nickel source and sulfur source in the present invention are low-priced and easy to obtain; after carbon addition, the cycle stability of the battery is greatly improved, the service life is increased, and the capacity is increased and stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The precursor precipitated product Cu in Example 1 1.81 S / NiS 2 SEM images of

[0032] Figure 2 The carbon-doped Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0033] Figure 3 The carbon-doped Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 TEM image of / C;

[0034] Figure 4 The carbon-doped Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 HRTEM image of / C;

[0035] Figure 5 The precursor Cu prepared in Example 1 1.81 S / NiS 2 XRD pattern of the precipitated product;

[0036] Figure 6 The carbon-doped Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / C XRD pattern;

[0037] Figure 7 Preparation of Cu precursor for Example 2 1.81 S / NiS 2 SEM image of the precipitated product;

[0038] Figure 8 The carbon-doped Cu prepared in Example 22 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0039] Fig. 9 The precursor Cu prepared in Example 3 1.81 S / NiS 2 SEM image of the precipitated product material;

[0040] Fig.10 The carbon-doped Cu prepared in Example 3 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0041] Fig.11 The precursor Cu prepared in Example 4 1.81 S / NiS 2 SEM images of the precipitated product material;

[0042] Fig.12 The carbon-doped Cu prepared in Example 4 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0043] Fig.13 The precursor Cu prepared in Example 5 1.81 S / NiS 2 SEM images of the precipitated product material;

[0044] Fig.14 The carbon-doped Cu prepared in Example 5 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0045] Fig.15 Preparation of Cu precursor for Example 6 1.81 S / NiS 2 SEM image of the precipitated nanosphere material;

[0046] Fig.16 The carbon-doped Cu prepared in Example 6 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0047] Fig.17 The precursor Cu prepared in Example 7 1.81 S / NiS 2 SEM image of the precipitated product material;

[0048] Fig.18 The carbon-doped Cu prepared in Example 7 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0049] Fig.19 The precursor Cu prepared in Example 8 1.81 S / NiS 2 SEM images of the precipitated product material;

[0050] Fig. 20 The carbon-doped Cu prepared in Example 8 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0051] Fig.21 The precursor Cu prepared in Example 9 1.81 S / NiS 2 SEM image of the flower-like material of the precipitation product;

[0052] Fig. 22 The carbon-doped Cu prepared in Example 9 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0053] Fig.23 Preparation of Cu precursor for Example 10 1.81 S / NiS 2 SEM image of the precipitated product;

[0054] Fig.24 The carbon-doped Cu prepared in Example 10 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0055] Fig.25 The precursor Cu prepared in Example 11 1.81 S / NiS 2 SEM image of the precipitated product material;

[0056] Fig.26The carbon-doped Cu prepared in Example 11 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0057] Fig. 27 The precursor Cu prepared in Example 12 1.81 S / NiS 2 SEM images of the precipitated product material;

[0058] Fig.28 The carbon-doped Cu prepared in Example 12 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0059] Fig.29 The precursor Cu prepared in Example 13 1.81 S / NiS 2 SEM images of the precipitated product material;

[0060] Fig.30 The carbon-doped Cu prepared in Example 13 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0061] Fig.31 Preparation of Cu precursor for Example 14 1.81 S / NiS 2 SEM image of the precipitated nanosphere material;

[0062] Fig.32 The carbon-doped Cu prepared in Example 14 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0063] Fig.33 The precursor Cu prepared in Example 15 1.81 S / NiS 2 SEM image of the precipitated product material;

[0064] Fig.34 The carbon-doped Cu prepared in Example 15 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0065] Fig.35 The precursor Cu prepared in Example 16 1.81 S / NiS 2 SEM images of the precipitated product material;

[0066] Fig.36 The carbon-doped Cu prepared in Example 16 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0067] Fig.37 The precursor Cu prepared in Example 17 1.81 S / NiS 2 SEM images of the precipitated product material;

[0068] Fig.38 The carbon-doped Cu prepared in Example 17 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0069] Fig.39 The carbon-doped Cu prepared in Example 18 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0070] Fig.40 The carbon-doped Cu prepared in Example 19 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0071] Fig.41 The carbon-doped Cu prepared in Example 20 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0072] Fig.42 The carbon-doped Cu prepared in Example 21 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / SEM image of C;

[0073] Fig.43 The carbon-doped Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / C as anode material for sodium ion batteries at 0.1A g -1 Cyclic stability test diagram under current density;

[0074] Fig.44 The carbon-doped Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / C as anode material for sodium-ion batteries at 1A g -1 Constant current charge and discharge curves under current density;

[0075] Fig.45 The carbon-doped Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / C as anode material for sodium-ion batteries at 1A g -1 Cyclic stability test diagram under current density;

[0076] Fig.46 The carbon-doped Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / C as rate diagram of negative electrode material for sodium ion batteries. DETAILED DESCRIPTION

[0077] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0078] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0079] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0080] Example 1

[0081] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0082] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, the mixture was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Figure 1 As shown in the figure, it can be seen that it is in the shape of microflowers with a size of 1-3 μm. 1.81 S / NiS 2 XRD pattern of precursor material Figure 6 shown.

[0083] 2)Cu 2 S / NiS 2 / C Preparation:

[0084] The dried precursor product was placed in a porcelain boat and calcined in an argon flow atmosphere at a heating rate of 2°C / min to a calcination temperature of 400°C for 2h to obtain the product Cu 2 S / NiS 2 / C, its SEM picture is as follows Figure 2 As shown in the figure, it can be seen that it is a flower-like structure composed of flake structures. Figure 3 shown.

[0085] The Cu obtained in this example 2 S / NiS 2 HRTEM of composite materials such as Figure 4 As shown, it is proved that the product is Cu 2 S and NiS 2 The XRD pattern of the composite is as follows Figure 6 As shown, it is proved that the product is Cu 2 S / NiS 2 / C.

[0086] Example 2 (for comparison)

[0087] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0088] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven. 120℃ The reaction was continued for 2.5 h. The mixture was cooled to room temperature and then quenched with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Figure 7 As shown, it can be seen from the figure that the morphology has also changed and is no longer flower-shaped.

[0089] 2)Cu 2 S / NiS 2 / C Preparation:

[0090] The dried precursor product was placed in a porcelain boat and calcined in an argon flow atmosphere at a heating rate of 2°C / min to a calcination temperature of 400°C for 2h to obtain the product Cu 2 S / NiS 2 / C, its SEM picture is as follows Figure 8 As shown in the figure, it can be seen that it is consistent with that before calcination, and it has a strip-like structure.

[0091] Example 3 (for comparison)

[0092] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0093] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven. 140℃ The reaction was continued for 2.5 h. The mixture was cooled to room temperature and then quenched with deionized H2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig. 9 As shown in the figure, it can be seen that it is a micro-flower-like and red blood cell-like structure with uneven morphology and a size of 1-3μm.

[0094] 2)Cu 2 S / NiS 2 / C Preparation:

[0095] The dried precursor product was placed in a porcelain boat and calcined in an argon flow atmosphere at a heating rate of 2°C / min to a calcination temperature of 400°C for 2h to obtain the product Cu 2 S / NiS 2 / C, its SEM picture is as follows Fig.10 As shown, it can be seen from the figure that it is consistent with that before calcination.

[0096] Example 4 (for comparison)

[0097] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0098] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven. 180℃ The reaction was continued for 2.5 h. The mixture was cooled to room temperature and then quenched with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.11 As shown in the figure, it can be seen that it is a micro-flower-like, cube-like and red blood cell-like structure with a size of 1-3μm.

[0099] 2)Cu 2 S / NiS 2 / C Preparation:

[0100] The dried precursor product was placed in a porcelain boat and calcined in an argon flow atmosphere at a heating rate of 2°C / min to a calcination temperature of 400°C for 2h to obtain the product Cu 2 S / NiS 2 / C, its SEM picture is as follows Fig.12 As shown, it can be seen from the figure that it is consistent with the precursor structure.

[0101] Example 5 (for comparison)

[0102] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0103] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven. 200℃ The reaction was continued for 2.5 h. The mixture was cooled to room temperature and then quenched with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.13 As shown in the figure, it can be seen that it is a flake structure, but the flower-like structure is not very obvious, and the size is 1-3μm.

[0104] 2)Cu 2 S / NiS 2 / C Preparation:

[0105] The dried precursor product was placed in a porcelain boat and calcined in an argon flow atmosphere at a heating rate of 2°C / min to a calcination temperature of 400°C for 2h to obtain the product Cu 2 S / NiS 2 / C, its SEM picture is as follows Fig.14 As shown, it can be seen from the figure that it is consistent with the precursor.

[0106] Example 6

[0107] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0108] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.394 g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, the mixture was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.15 As shown in the figure, it can be seen that it is a flake structure, partly a flower-like structure, and mostly irregular, with a size of 1-3 μm.

[0109] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig.16 As shown in the figure, it can be seen that the morphology is consistent with the precursor.

[0110] Example 7

[0111] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0112] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.591g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, the mixture was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.17 As shown in the figure, it can be seen that it is a flower-like structure composed of nanosheets, but the output is relatively small and the size is 1-3μm.

[0113] 2)Cu 2 S / NiS2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig.18 As shown in the figure, it can be seen that the morphology is consistent with the precursor.

[0114] Example 8 (for comparison)

[0115] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0116] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 Oh, 0.788g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, the mixture was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.19 As shown in the figure, it can be seen that it is a flower-like structure and a block-like structure with uneven morphology. Most of the flower-like materials have a size of 1-3 μm.

[0117] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig. 20 As shown in the figure, it can be seen that the morphology is consistent with the precursor

[0118] Example 9 (for comparison)

[0119] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0120] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 Oh, 0.985g Ni(NO 3 ) 2 6H 2O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, the mixture was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.21 As shown, it can be seen from the figure that it is a block structure.

[0121] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig. 22 As shown in the figure, it can be seen that the morphology is consistent with the precursor.

[0122] By comparison Figure 1 and Figure 17-Figure 22 It can be seen that with the increase in the ratio between the nickel source and the copper source, the sulfides are more likely to aggregate together during the hydrothermal process, and the nickel source is prone to form a single sulfide, resulting in unsuccessful composite, which is uneven in morphology and easily forms a block structure and aggregates together.

[0123] Example 10 (for comparison)

[0124] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0125] 1) Preparation of precursors: Weigh 0.45g PVP, 0.187 g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, the mixture was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.23 As shown in the figure, it can be seen that it is a flaky structure with many fragments and irregularity.

[0126] 2)Cu 2 S / NiS2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig.24 As shown in the figure, it can be seen that the morphology is consistent with the precursor.

[0127] Example 11 (for comparison)

[0128] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0129] 1) Preparation of precursors: Weigh 0.675g PVP, 0.187 g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, the mixture was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.25 As shown, it can be seen from the figure that a small part of it is a circular flower-like structure composed of flakes, and the rest is an irregular flake structure.

[0130] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig.26 As shown in the figure, it can be seen that the morphology is consistent with the precursor.

[0131] Example 12 (for comparison)

[0132] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0133] 1) Preparation of precursors: Weigh 0.9g PVP, 0.187 g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, the mixture was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig. 27 As shown in the figure, it can be seen that it is a pie-shaped structure and a block-shaped structure. The two morphologies are uneven, and the size of most pie-shaped structure materials is 1-3μm.

[0134] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig.28 As shown in the figure, it can be seen that the morphology is consistent with the precursor.

[0135] Example 13 (for comparison)

[0136] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0137] 1) Preparation of precursors: Weigh 1.125 g PVP, 0.187 g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, 0.456 g of thiourea was added, magnetic stirring was continued for 10 min, and then the mixture was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, the mixture was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.29 As shown in the figure, it can be seen that it is a mixture of three structures: pie-shaped, flower-shaped and block-shaped structures composed of flakes, and most of them are block-shaped structures composed of flakes.

[0138] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig.30 As shown in the figure, it can be seen that the morphology is consistent with the precursor.

[0139] By comparison Figure 1 and Figure 23-Figure 30 ,It can be seen that 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 a pancake-like structure and finally to a spherical structure, which easily forms a mixed result of multiple morphologies.

[0140] Example 14 (for comparison)

[0141] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0142] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, and then 0.912g The thiourea was stirred magnetically for 10 min and then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling to room temperature, the thiourea was heated with deionized H 2 The precursor was washed 4 times by centrifugation, washed 2 times by ethanol, and dried under vacuum at 60℃ for 12h. The SEM image is shown in Fig.31 As shown in the figure, it can be seen that it is a spherical structure, but most of it is adhered together, irregular, and has a size of 1-3μm.

[0143] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig.32 As shown in the figure, it can be seen that the morphology is consistent with the precursor.

[0144] Example 15 (for comparison)

[0145] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0146] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, and then 1.368After the thiourea was stirred magnetically for 10 min, it was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, it was heated with deionized H 2 The precursor was washed 4 times by centrifugation, washed 2 times by ethanol, and dried under vacuum at 60℃ for 12h. The SEM image is shown in Fig.33 As shown in the figure, it can be seen that it is a small spherical particle mixed with a larger spherical stick structure, but the output is relatively small.

[0147] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig.34 As shown in the figure, it can be seen that the morphology is consistent with the precursor.

[0148] Example 16 (for comparison)

[0149] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0150] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, and then 1.824 After the thiourea was stirred magnetically for 10 min, it was transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling naturally to room temperature, it was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.35 As shown in the figure, it can be seen that it is a block structure stuck together with uneven morphology.

[0151] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and its SEM image is shown in Fig.36 As shown in the figure, it can be seen that the morphology is consistent with the precursor

[0152] Example 17 (for comparison)

[0153] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0154] 1) Preparation of precursor: Weigh 0.225g PVP, 0.187g CuSO 4 ·5H 2 O, 0.197g Ni(NO 3 ) 2 6H 2 O was placed in a 50 mL beaker, 35 mL of ethylene glycol was added, magnetic stirring was performed for 10 min to dissolve, and then 2.28g The thiourea was stirred magnetically for 10 min and then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for 2.5 h. After cooling to room temperature, the thiourea was heated with deionized H 2 O centrifugation wash 4 times, ethanol wash 2 times, 60 ℃ vacuum drying 12h, collect the precursor Cu 1.81 S / NiS 2 The precipitated product. Its SEM image is as follows Fig.37 As shown in the figure, it can be seen that it is a block structure aggregated together, most of which are 1-3μm in size.

[0155] 2)Cu 2 S / NiS 2 / C was prepared in the same manner as in Example 1, and the SEM image of the product is shown in Fig.38 As shown in the figure, it can be seen that the morphology is consistent with the precursor

[0156] By comparison Figure 1 and Figure 31-Figure 38 It can be seen that with the increase in the amount of sulfur source used, the sulfides are more likely to stick together during the hydrothermal process, and do not form a flower-like structure of nanosheets, but more of a spherical structure, and the sizes of the balls are different. The more the amount used, the larger the size of the balls and the more uniform the morphology.

[0157] Embodiment 18

[0158] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0159] 1) The preparation of the precursor is the same as in Example 1;

[0160] 2)Cu 2 S / NiS 2 / C Preparation:

[0161] The dried precursor product was placed in a porcelain boat and calcined in an argon flow atmosphere at a heating rate of 2°C / min to a calcination temperature of 300°C for 2h to obtain the product Cu 2 S / NiS 2 / C, its SEM picture is as follows Fig.39 As shown, it can be seen from the figure that it is a flower-like structure composed of nanosheets.

[0162] Example 19 (for comparison)

[0163] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0164] 1) The preparation of the precursor is the same as in Example 1;

[0165] 2)Cu 2 S / NiS 2 / C Preparation:

[0166] The dried precursor product was placed in a porcelain boat and calcined in an argon flow atmosphere at a heating rate of 2°C / min until the calcination temperature was 500℃ , calcination time 2h, the final product Cu 2 S / NiS 2 / C, its SEM picture is as follows Fig.40 As shown in the figure, it can be seen that the flower-like structure collapsed and only fragments appeared.

[0167] Example 20 (for comparison)

[0168] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0169] 1) The preparation of the precursor is the same as in Example 1;

[0170] 2)Cu 2 S / NiS 2 / C Preparation:

[0171] The dried precursor product was placed in a porcelain boat and calcined in an argon flow atmosphere at a heating rate of 2°C / min until the calcination temperature was 600℃ , calcination time 2h, the final product Cu 2 S / NiS 2 / C, its SEM picture is as follows Fig.41 As shown in the figure, it can be seen that its structure has completely changed and has an irregular morphology.

[0172] Example 21 (for comparison)

[0173] A method for preparing a cuprous sulfide / nickel disulfide / carbon composite material comprises the following steps:

[0174] 1) The preparation of the precursor is the same as in Example 1;

[0175] 2)Cu 2 S / NiS 2 / C Preparation:

[0176] The dried precursor product was placed in a porcelain boat and calcined in an argon flow atmosphere at a temperature of700℃ , calcination time 2h, heating rate 2℃ / min, the final product Cu 2 S / NiS 2 / C, its SEM picture is as follows Fig.42 As shown in the figure, it can be seen that its morphology is completely different from that of Example 1, and is a block structure.

[0177] Performance Test:

[0178] The product of Example 1 is used as a negative electrode material for sodium ion batteries to prepare sodium batteries, specifically:

[0179] The cuprous sulfide / nickel disulfide / carbon composite material is an active material. After being uniformly mixed with conductive carbon black and PVDF in a ratio of 7:2:1, it is uniformly dispersed in NMP by magnetic stirring for 8 hours. The uniformly mixed slurry is coated on copper foil by an applicator, placed in a vacuum drying oven at 80°C, and pressed by a tablet press after drying for 24 hours. It is then cut into a small circular electrode sheet by a sheet cutter. The prepared electrode sheet is assembled into a button battery in a glove box filled with high-purity argon and with a water-oxygen value of ≤0.01ppm. The electrolyte is NaCF 3 SO 3 +DEGDME, the purity of the sodium sheet is Na≥99.99%, the thickness is 0.5mm, and it is cut into the size of the electrode sheet after rolling.

[0180] The specific method of assembling the battery is as follows: add 1 drop of electrolyte on the positive electrode shell of the battery and place the electrode sheet, then add 1 drop of electrolyte and place the glass fiber, add 3 drops of electrolyte on the glass fiber and place the sodium sheet as the counter electrode, then place two pieces of foam nickel, add 4 drops of electrolyte, cover the negative electrode shell, press and seal the battery with a hydraulic press, and leave it for 12 hours.

[0181] Specific test process: After assembling the sodium ion half-cell, set the process steps on the Xinwei tester, first discharge at a constant current to 0.1V, then charge at a constant current to 3V, and repeat this cycle for a certain number of times. The active material load of the electrode sheet is about 1.0mgcm -2 .

[0182] The test results and data are as follows:

[0183] Fig.43 The carbon-doped flower-like Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / C as anode material for sodium ion batteries at 0.1A g -1 Cyclic stability test diagram under current density; it can stably cycle for more than 100 cycles at this current density, showing good cycle stability.

[0184] Fig.44 The carbon-doped flower-like Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / C as anode material for sodium ion batteries at 1A g -1 Constant current charge and discharge curve under current density; it can stably cycle for more than 1000 cycles at this current density, showing good cycle stability.

[0185] Fig.45 The current density is 1A g -1 The charge and discharge curves have an average discharge voltage of about 1.8V, and the second and third cycle curves have a high degree of overlap, indicating good reversibility.

[0186] Fig.46 The carbon-doped Cu prepared in Example 1 2 S / NiS 2 Composite material Cu 2 S / NiS 2 / C as a negative electrode material for sodium ion batteries; it can be seen from the figure that the composite material has good rate performance. In addition, after undergoing two rounds of high current rate cycles, it still has a high capacity, indicating that it has good electrochemical performance.

[0187] The underlined data above do not meet the requirements of the present invention.

[0188] The description of the above embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and 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 present 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 comprises 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 in a protective atmosphere to obtain a Cu2S / NiS2 / C composite material.

2. The preparation method according to claim 1, characterized in that: Step 1) The preparation method is: disperse the copper source, nickel source, polyvinyl pyrrolidone and sulfur source in a solvent, and perform hydrothermal reaction to obtain Cu 1.81 S / NiS2 flower-like material.

3. The preparation method according to claim 2, characterized in that: In step 1), the molar ratio of the polyvinyl pyrrolidone, the copper source, the nickel source and the sulfur source is 0.03:0.75:0.65-2.25:

6.

4. The preparation method according to claim 2 or 3, characterized in that: The solvent is ethylene glycol.

5. The preparation method according to claim 2 or 3, characterized in that: The sulfur source is thiourea.

6. The preparation method according to claim 2 or 3, characterized in that: The polyvinyl pyrrolidone is PVP, K16-18, and the molecular weight M=8000.

7. The preparation method according to claim 2, characterized in that: In step 1), the hydrothermal reaction is carried out at 130-170° C. for 2-3 hours.

8. The preparation method according to claim 1 or 2, characterized in that: In step 2), the annealing refers to annealing at 300-400° C. for 2 h.

9. A cuprous sulfide / nickel disulfide / carbon composite material prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The cuprous sulfide / nickel disulfide / carbon composite material is a flower-like structure composed of nanosheets, a cross-shaped structure, and a size of 1-3 μm.

10. Use of the cuprous sulfide / nickel disulfide / carbon composite material according to claim 9 in a battery, characterized in that: Used to prepare negative electrodes for sodium ion batteries.

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