A bismuth triselenide / zinc selenide@nitrogen-carbon composite material, a preparation method thereof and application thereof in sodium ion batteries

Abstract

The application provides a kind of bismuth selenide / zinc selenide@nitrogen-carbon composite material, its preparation method and application in sodium ion battery, the application first disperses zinc source, bismuth source and organic ligand in organic solvent, solvent hot reaction is carried out, precursor Bi / Zn-MOF is obtained, and then selenization is carried out to obtain Bi2Se3 / ZnSe@NC nanowire cluster, which is in the form of radial rays.The preparation method of the application has high yield and low cost.The product has a radial structure composed of linear structures, which can provide a large specific surface area;During the charging and discharging process, more active sites are provided, the volume expansion problem is solved, the battery has better stability, and the nanomaterial is safe, environmentally friendly, cheap and has other advantages.The material is applied to the negative electrode material of sodium ion battery, has good cycle performance, high energy density and other advantages.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery composite material technology, specifically relating to a bismuth triselenide / zinc selenide@nitrogen carbon composite material, its preparation method, and its application in sodium-ion batteries. The prepared binary metal selenide Bi2Se3 / ZnSe@NC is used as a negative electrode material for sodium-ion batteries. Background Technology

[0002] Given the increasing environmental pollution and energy consumption, the development of efficient energy storage devices has become a research hotspot. For the past few decades, lithium-ion batteries have dominated as the most successful energy storage device, especially in portable electronic devices and electric vehicles. However, their relatively high cost and uneven distribution of lithium resources make them unsuitable for large-scale energy storage.

[0003] Sodium, as one of the most abundant metallic elements on Earth, is evenly distributed and exhibits chemical properties similar to lithium. Therefore, low-cost and high-efficiency sodium-ion batteries have great potential to dominate future large-scale energy storage systems.

[0004] In recent years, transition metal selenides have been considered promising anode materials for sodium-ion batteries due to their diverse material types, simple preparation, structural stability, and high theoretical capacity. Compared with homologous metal compounds, metal selenides exhibit superior reversibility and smaller volume change in their overall electrochemical performance as anodes in sodium-ion batteries. Furthermore, metal selenides demonstrate better electronic conductivity than metal sulfides and metal oxides, and their sodium-containing compounds, such as Na... x Se is also better than Na x O and Na x S exhibits superior ionic conductivity. Therefore, metal selenides possess rapid electrochemical reaction kinetics to achieve excellent rate performance.

[0005] Despite the numerous advantages of metal selenides for sodium storage, several challenging issues hinder their commercial application, such as poor capacity and cycling stability. Therefore, it is essential to provide a metal selenide material that improves both its capacity and cycling stability. Summary of the Invention

[0006] The purpose of this invention is to provide a bismuth triselenide / zinc selenide@nitrogen carbon composite material and its preparation method. The method utilizes inexpensive raw materials to prepare Bi2Se3 / ZnSe@NC nanowire clusters with a size of approximately 4-6 μm. Furthermore, the preparation method has high yield and low cost.

[0007] Another objective of this invention is to provide an application of a bismuth triselenide / zinc selenide@nitrogen carbon composite material in sodium-ion batteries. By using the prepared bismuth triselenide / zinc selenide@nitrogen carbon composite material as a negative electrode material for sodium-ion batteries, the battery's lifespan, capacity, and cycle stability are improved.

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

[0009] A method for preparing a bismuth triselenide / zinc selenide@nitrogen carbon composite material includes the following steps:

[0010] 1) Disperse zinc source, bismuth source and organic ligand in organic solvent and carry out solvothermal reaction to obtain precursor Bi / Zn-MOF;

[0011] 2) The precursor Bi / Zn-MOF and selenium powder obtained in step 1) were loaded into a ceramic boat and calcined to obtain a linear Bi2Se3 / ZnSe@NC composite material.

[0012] In step 1), the molar ratio of the zinc source, bismuth source, and organic ligand is 1:1:3; the zinc source is a soluble zinc salt, preferably zinc nitrate hexahydrate; the bismuth source is bismuth nitrate pentahydrate; the organic ligand is 2-methylimidazole; the organic solvent is glycerol; and the concentration of the zinc source in the organic solvent is 0.02–0.1 mol·L⁻¹. -1 Preferably 0.05 mol·L -1 ;

[0013] In step 1), the solvothermal reaction conditions are 150-190°C for 2-4 hours, preferably 160°C for 3 hours;

[0014] In step 1), after the hydrothermal reaction is completed, the precursor Bi / Zn-MOF is obtained by centrifugation, washing and drying.

[0015] In step 2), the mass ratio of the precursor Bi / Zn-MOF to selenium powder is 1:3;

[0016] In step 2), the calcination conditions are 600–700°C for 2 hours, preferably 600°C for 2 hours. Calcination is carried out in a tube furnace under an argon atmosphere.

[0017] This invention provides a bismuth triselenide / zinc selenide@nitrogen carbon composite material, prepared using the method described above. The bismuth triselenide / zinc selenide@nitrogen carbon composite material is a nanowire cluster structure material, consisting of clusters of nanowires with a length of 4-6 μm and a diameter of 40-50 nm.

[0018] This invention first synthesizes Bi / Zn-MOF via a one-step hydrothermal method, and then uses a tube furnace for selenization to convert the Bi / Zn-MOF into a Bi2Se3 / ZnSe@NC nanowire cluster composite material. The one-step hydrothermal method not only facilitates the formation of regularly shaped crystals but also promotes the formation of a single-phase product. The linear structure not only increases specific surface area and reduces ion transport paths, thus increasing conductivity, but also suppresses volume expansion, thereby improving battery cycle stability.

[0019] This invention employs a one-step hydrothermal method to provide a relatively stable and continuous reaction environment. In a sealed hydrothermal reactor, the raw materials dissolve in the solvent under high temperature and pressure, reaching a supersaturated state, followed by uniform nucleation and growth, maintaining a complete radial structure. Because the process is completed in one step, the linear structure is not interrupted during growth, resulting in a more complete structure with fewer defects. The one-step hydrothermal method allows the metal salt and the ligand 2-methylimidazole to react in a stable environment, which contributes to the formation of the linear structure morphology. From a reaction kinetics perspective, the one-step hydrothermal method avoids interference from intermediate steps. It allows the reaction to proceed at a relatively stable rate, with continuous changes in the concentrations of various substances in the reaction system, which is beneficial for forming a single-phase product.

[0020] Due to the synergistic effect of the two metal ions, bimetallic selenides exhibit relatively higher electronic conductivity and richer redox reactions compared to their corresponding monometallic selenides. Among them, zinc selenide combines conversion and alloying reactions, possessing high theoretical specific capacity, a suitable charge-discharge platform, and low toxicity, making it a promising anode material. However, the performance of ZnSe remains affected by its low intrinsic conductivity and drastic volume changes during charge-discharge, ultimately leading to poor cycle stability and rate performance. Introducing Bi₂Se₃ to form a composite material, the mixed metal selenide increases the conductivity of redox reaction sites, thereby improving the electrochemical performance of the electrode. Employing a bimetallic selenide material form and effectively designing the material's microstructure can effectively mitigate volume expansion and prevent structural pulverization, thus preventing the structural collapse of the electrode material.

[0021] This invention provides the application of a bismuth triselenide / zinc selenide@nitrogen carbon composite material in sodium-ion batteries. The bismuth triselenide / zinc selenide@nitrogen carbon composite material is used as an active material to prepare the negative electrode of a sodium-ion battery, thereby preparing a sodium-ion battery.

[0022] Specifically, bismuth triselenide / zinc selenide@nitrogen carbon composite material is used as the active material. It is mixed evenly with conductive carbon black and polyvinylidene fluoride in a ratio of 8:1:1 or 7:2:1. NMP is then added dropwise, and the mixture is magnetically stirred for 6-8 hours to disperse it evenly. 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 tablets using a tablet press and then cut into small circular electrode sheets using a cutting machine. The electrode sheets are then 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 NaPF6+DEGDME, the sodium sheet has a purity of Na≥99.99%, a thickness of 0.5mm, and is rolled and cut to the size of the electrode sheet.

[0023] 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, add 3 drops of electrolyte to the glass fiber and place the sodium plate 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.

[0024] This invention provides a method for preparing Bi₂Se₃ / ZnSe@NC nanowire cluster structure material. Zinc and bismuth sources are used as raw materials, and 2-methylimidazole is used as an organic ligand. A mixed solution is synthesized into Bi / Zn-MOF through a solvothermal reaction. Selenium powder is used as a selenizing agent, and selenization is performed at high temperature to generate Bi₂Se₃ / ZnSe@NC nanowire cluster structure material. This material provides numerous active sites during charge and discharge, solving the volume expansion problem and improving battery stability. Furthermore, this nanomaterial is safe, environmentally friendly, and inexpensive. The high boiling point and high viscosity of glycerol used in this invention reduce the diffusion rate of reactants, allowing for a more ordered arrangement of reactants during nucleation and growth, which is beneficial for the slow growth of nanowires along a specific direction. Glycerol can be adsorbed onto the surface of nanoparticles, controlling the growth direction and morphology of nanoparticles by reducing surface energy, preferentially promoting the growth of nanowires along specific crystal planes. Appropriate low temperature inhibits rapid nucleation and random growth, and a sufficiently long reaction time allows atoms ample time to align and grow into nanowires along a specific direction. If the reactant concentration is within a suitable range, it ensures a stable reaction and avoids the formation of large amounts of nucleation and granular or blocky morphologies. Anisotropic crystal growth causes differences in the growth rate of nanomaterials across different crystal planes. Under the influence of glycerol, growth on specific crystal planes is inhibited, while other crystal planes grow preferentially, ultimately forming nanowires. Furthermore, the 2-methylimidazole ligand in this invention decomposes, generating a large number of chemically active carbon (C) atoms and nitrogen-containing small molecules or groups, providing carbon and nitrogen sources for the products. Carbon atoms interact through covalent bonds to form layered substances with a certain thickness and structure. In this invention, carbon is introduced into the material, and some of this carbon doping forms a carbon layer on the material's surface through covalent bonds. This carbon layer can coat the surface of the positive or negative electrode material, existing within the organic electrolyte environment of the battery, interacting with the positive and negative electrodes, separator, and electrolyte, and participating in the battery's charging and discharging process. Carbon is incorporated into the crystal lattice of other materials in atomic form, altering their electronic structure and physicochemical properties. For example, in nitrogen-doped carbon materials, nitrogen atoms enter the carbon lattice, introducing more active sites and enhancing the material's electrochemical activity. Some carbon is also incorporated as a uniform thin film coating on the surface of active material particles. This carbon layer prevents direct contact between the active material and the electrolyte, reducing side reactions and improving electron conduction efficiency.

[0025] The Bi2Se3 / ZnSe@NC composite material prepared in this invention is in 1Ag -1 After 1200 cycles at current density, the display showed 386 mAh g. -1The high reversible capacity, high specific capacity, and stable cycling performance indicate that Bi₂Se₃ / ZnSe@NC is an excellent and promising sodium-ion anode material. The synthesis of this nitrogen-doped carbon nanostructure composite material is achieved through a simple solvothermal process followed by selenization. The unique structure of the nanowire clusters exposes more active sites, allowing for sufficient contact between the electrolyte and electrode materials, shortening the diffusion distance of electrons and ions, while the carbon layer provides both a conductive substrate and structural support. Furthermore, the introduction of nitrogen atoms provides more defects, which can further increase electronic conductivity. The nanomaterial possesses a relatively large electrolyte contact area, abundant electrochemical active sites, and strong surface strain resistance, thereby shortening the sodium-ion transition distance, improving capacity, and exhibiting excellent structural stability. Moreover, more sodium-storage active sites can be obtained in the specific heterostructure of metal selenides to improve sodium storage performance. The different redox potentials of different components in various metal selenides often result in asynchronous electrochemical reactions, leading to the suppression of strain during sodium insertion / extraction.

[0026] Compared with existing technologies, the application of the Bi2Se3 / ZnSe@NC nanocomposite material prepared in this invention in sodium-ion batteries is novel and represents the first combined application. The prepared composite material has a nanowire cluster structure, with the wires forming a special radial structure, which can provide a large specific surface area. The prepared nanocomposite material has stable performance, is not easily deformed in air, and is easy to store. When used as a negative electrode material for sodium-ion batteries, the prepared nanocomposite material has a large specific capacity and good cycle performance. The prepared nanocomposite material has excellent conductivity, shortens the electron transport distance in the nanowires, and improves the electrochemical reaction rate of the electrode material. The raw materials used in this invention are inexpensive, the synthesis process is simple, and it can be mass-produced. Attached Figure Description

[0027] Figure 1 SEM image of the Bi / Zn-MOF nanowire clusters precursor prepared in Example 1;

[0028] Figure 2 SEM image of the Bi2Se3 / ZnSe@NC nanowire clusters prepared in Example 1;

[0029] Figure 3 The XRD pattern of the Bi2Se3 / ZnSe@NC nanowire clusters prepared in Example 1;

[0030] Figure 4 TEM image (left) and magnified view (right) of the Bi2Se3 / ZnSe@NC nanowire clusters prepared in Example 1;

[0031] Figure 5Mapping diagram of Bi2Se3 / ZnSe@NC nanowire clusters prepared for implementation of column 1;

[0032] Figure 6 HRTEM image of the Bi2Se3 / ZnSe@NC nanowire clusters prepared in Example 1;

[0033] Figure 7 SEM image of Bi2Se3 / ZnSe@NC prepared in Example 2;

[0034] Figure 8 SEM image of Bi2Se3 / ZnSe@NC prepared in Example 3;

[0035] Figure 9 SEM image of Bi2Se3 / ZnSe@NC prepared in Example 4;

[0036] Figure 10 SEM image of Bi2Se3 / ZnSe@NC prepared in Example 5;

[0037] Figure 11 SEM image of Bi2Se3 / ZnSe@NC prepared in Example 6;

[0038] Figure 12 SEM image of Bi2Se3 / ZnSe@NC prepared in Example 7;

[0039] Figure 13 SEM image of Bi2Se3 / ZnSe@NC prepared in Example 8;

[0040] Figure 14 SEM image of Bi2Se3 / ZnSe@NC prepared in Example 9;

[0041] Figure 15 SEM image of the Bi2Se3 / ZnSe@NC nanowire clusters prepared in Example 10;

[0042] Figure 16 SEM image of Bi2Se3@NC prepared in Example 11;

[0043] Figure 17 SEM image of ZnSe@NC prepared in Example 12;

[0044] Figure 18 The Bi₂Se₃ / ZnSe@NC nanowire cluster material prepared in Example 1 was used as a negative electrode material for a sodium-ion battery in 0.2 Ag⁻¹. -1 Cyclic performance test graph at current density;

[0045] Figure 19The Bi₂Se₃ / ZnSe@NC nanowire cluster material prepared in Example 1 was used as a negative electrode material for a sodium-ion battery in 0.2 Ag⁻¹. -1 Test graph of charge-discharge curves at current density;

[0046] Figure 20 The Bi₂Se₃ / ZnSe@NC nanowire cluster material prepared in Example 1 was used as a sodium-ion battery anode material in 1Ag -1 Cyclic performance test graph at current density;

[0047] Figure 21 The Bi₂Se₃ / ZnSe@NC nanowire cluster material prepared in Example 1 was used as a sodium-ion battery anode material in 1Ag -1 Test graph of charge-discharge curves at current density;

[0048] Figure 22 The Bi₂Se₃@NC material prepared in Example 11 was used as a negative electrode material for a sodium-ion battery in 0.2 Ag⁻¹. -1 Cyclic performance test graph at current density;

[0049] Figure 23 The Bi₂Se₃ / ZnSe@NC material prepared in Example 11 was used as a negative electrode material for a sodium-ion battery in 0.2 Ag⁻¹. -1 Test graph of charge-discharge curves at current density;

[0050] Figure 24 The ZnSe@NC material prepared in Example 12 was used as a negative electrode material for a sodium-ion battery in 0.2 Ag. -1 Cyclic performance test graph at current density;

[0051] Figure 25 The ZnSe@NC material prepared in Example 12 was used as a negative electrode material for a sodium-ion battery in 0.2 Ag. -1 Charge-discharge curve test graph at current density. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below 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.

[0053] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0054] 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.

[0055] Example 1

[0056] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0057] 1) Preparation of Bi / Zn-MOF precursor:

[0058] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred at room temperature for 12 h. The mixture was then transferred to a 50 mL polytetrafluoroethylene (PTFE) reactor and reacted at 160 °C for 3 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 Bi / Zn-MOF precursor precipitate was collected. Its SEM image is shown below. Figure 1 As shown in the figure, it can be seen that it is a cluster of nanowires with a length of about 4-6 μm.

[0059] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0060] 0.1 g of Bi / Zn-MOF precursor and selenium powder were weighed and placed in two separate ceramic boats at a mass ratio of 1:3. The boat containing the selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at 600℃ for 2 hours. The Bi₂Se₃ / ZnSe@NC mixture was collected, and its SEM image is shown below. Figure 2 As shown in the figure, it can be seen that it is in the form of nanowire clusters with a length of approximately 4-6 μm. The XRD pattern of the Bi₂Se₃ / ZnSe@NC composite material obtained in this embodiment is shown below. Figure 3 As shown, the obtained product is Bi2Se3 / ZnSe@NC. The TEM image of the Bi2Se3 / ZnSe@NC composite material obtained in this embodiment is shown below. Figure 4 As shown, the obtained material exhibits a nanowire cluster morphology. Transmission mapping is as follows... Figure 5 As shown, this demonstrates that the elemental distribution in this material is relatively uniform. Its HRTEM image is shown below. Figure 6 As shown, its lattice fringes demonstrate the presence of two individual substances in this composite material.

[0061] Example 2 (as a comparison)

[0062] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0063] 1) Preparation of Bi / Zn-MOF precursor:

[0064] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The solution was then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven. 110℃ The reaction was carried out for 3 hours. After naturally cooling to room temperature, the product was washed 4 times by centrifugation with deionized H2O, 2 times by washing with ethanol, and dried under vacuum at 60°C for 12 hours. The precursor Bi / Zn-MOF precipitate was collected.

[0065] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0066] 0.1 g of Bi / Zn-MOF precursor and selenium powder were weighed and placed in two separate ceramic boats at a mass ratio of 1:3. The boat containing the selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at a heating rate of 10 °C / min until the calcination temperature reached 600 °C. The calcination time was 2 h. The Bi₂Se₃ / ZnSe@NC mixture was collected, and its SEM image is shown below. Figure 7 As shown in the figure, it can be seen that it is a cluster of linear materials.

[0067] Figure 7 It can be seen that the hydrothermal temperature was low during the synthesis of Bi / Zn-MOF in Example 2, and the nanowires could not aggregate into radial materials.

[0068] Example 3 (as a comparison)

[0069] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0070] 1) Preparation of Bi / Zn-MOF precursor:

[0071] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The solution was then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven. 140℃ The reaction was carried out for 3 hours. After naturally cooling to room temperature, the product was washed 4 times by centrifugation with deionized H2O, 2 times by washing with ethanol, and dried under vacuum at 60°C for 12 hours. The precursor Bi / Zn-MOF precipitate was collected.

[0072] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0073] 0.1 g of Bi / Zn-MOF precursor and selenium powder were weighed and placed in two ceramic boats at a mass ratio of 1:3. The ceramic boat containing selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at a heating rate of 10 °C / min until the calcination temperature reached 600 °C. The calcination time was 2 h. The Bi₂Se₃ / ZnSe@NC mixture was collected, and its SEM image is shown below. Figure 8 As shown in the figure, it can be seen that it has an irregular blocky structure.

[0074] Example 4 (as a comparison)

[0075] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0076] 1) Preparation of Bi / Zn-MOF precursor:

[0077] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The solution was then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven. 200℃ The reaction was carried out for 3 hours. After naturally cooling to room temperature, the product was washed 4 times by centrifugation with deionized H2O, 2 times by washing with ethanol, and dried under vacuum at 60°C for 12 hours. The precursor Bi / Zn-MOF precipitate was collected.

[0078] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0079] 0.1 g of Bi / Zn-MOF precursor and selenium powder were weighed and placed in two separate ceramic boats at a mass ratio of 1:3. The boat containing the selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at a heating rate of 10 °C / min until the calcination temperature reached 600 °C. The calcination time was 2 h. The Bi₂Se₃ / ZnSe@NC mixture was collected, and its SEM image is shown below. Figure 9 As shown in the figure, it can be seen that it is a collapsed linear structure.

[0080] Figure 9 It can be seen that the hydrothermal temperature was high when Bi / Zn-MOF was synthesized in Example 4, and the nanowires were prone to collapse under high temperature calcination, exhibiting a collapsed linear structure.

[0081] Example 5 (as a comparison)

[0082] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0083] 1) Preparation of Bi / Zn-MOF precursor:

[0084] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The mixture was then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for reaction. 1h After naturally cooling to room temperature, the product was washed four times by centrifugation with deionized H2O, twice by washing with ethanol, and vacuum dried at 60℃ for 12 h. The precursor Bi / Zn-MOF precipitate was then collected.

[0085] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0086] 0.1 g of Bi / Zn-MOF precursor and selenium powder were weighed and placed in two separate ceramic boats at a mass ratio of 1:3. The boat containing the selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at a heating rate of 10 °C / min until the calcination temperature reached 600 °C. The calcination time was 2 h. The Bi₂Se₃ / ZnSe@NC mixture was collected, and its SEM image is shown below. Figure 10 As shown in the figure, it can be seen that it has an irregular blocky structure.

[0087] Example 6 (as a comparison)

[0088] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0089] 1) Preparation of Bi / Zn-MOF precursor:

[0090] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The mixture was then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for reaction. 2h。 After naturally cooling to room temperature, the product was washed four times by centrifugation with deionized H2O, twice by washing with ethanol, and vacuum dried at 60℃ for 12 h. The precursor Bi / Zn-MOF precipitate was then collected.

[0091] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0092] 0.1 g of Bi / Zn-MOF precursor and selenium powder were weighed and placed in two separate ceramic boats at a mass ratio of 1:3. The boat containing the selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at a heating rate of 10 °C / min until the calcination temperature reached 600 °C. The calcination time was 2 h. The Bi₂Se₃ / ZnSe@NC mixture was collected, and its SEM image is shown below. Figure 11As shown in the figure, it can be seen that it has an irregular blocky structure.

[0093] Figure 11 It can be seen that the hydrothermal time was short during the synthesis of Bi / Zn-MOF in Example 6, the reaction was incomplete, and a linear structure was not formed.

[0094] Example 7 (as a comparison)

[0095] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0096] 1) Preparation of Bi / Zn-MOF precursor:

[0097] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The mixture was then transferred to a 50 mL polytetrafluoroethylene reactor and placed in an oven at 160 °C for reaction. 4h After naturally cooling to room temperature, the product was washed four times by centrifugation with deionized H2O, twice by washing with ethanol, and vacuum dried at 60℃ for 12 h. The precursor Bi / Zn-MOF precipitate was then collected.

[0098] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0099] 0.1 g of Bi / Zn-MOF precursor and selenium powder were weighed and placed in two separate ceramic boats at a mass ratio of 1:3. The boat containing the selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at a heating rate of 10 °C / min until the calcination temperature reached 600 °C. The calcination time was 2 h. The Bi₂Se₃ / ZnSe@NC mixture was collected, and its SEM image is shown below. Figure 12 As shown in the figure, it can be seen that it is a clustered linear structure, but part of it has collapsed.

[0100] Figure 12 It can be seen that the hydrothermal time and reaction time were relatively long when synthesizing Bi / Zn-MOF in Example 7. Although there was a linear structure, some of the structure had collapsed.

[0101] Example 8 (as a comparison)

[0102] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0103] 1) Preparation of Bi / Zn-MOF precursor:

[0104] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The mixture was then transferred to a 50 mL polytetrafluoroethylene (PTFE) reactor and reacted at 160 °C for 3 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 Bi / Zn-MOF precursor precipitate was collected.

[0105] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0106] Weigh 0.1g of Bi / Zn-MOF precursor and selenium powder into two ceramic boats at a mass ratio of 1:3. Place the ceramic boat containing selenium powder at the upwind end and calcine it in an argon atmosphere with a heating rate of 10℃ / min until the calcine temperature is reached. 400℃, calcination time 2 hours Bi2Se3 / ZnSe@NC was collected, and its SEM images are shown below. Figure 13 As shown in the figure, it can be seen that it is an irregular linear structure of aggregates.

[0107] Figure 13 It can be seen that the calcination temperature was low during the synthesis of Bi2Se3 / ZnSe@NC in Example 8, and the selenium powder was not completely reacted, with some selenium powder agglomerated into lumps.

[0108] Example 9 (as a comparison)

[0109] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0110] 1) Preparation of Bi / Zn-MOF precursor:

[0111] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The mixture was then transferred to a 50 mL polytetrafluoroethylene (PTFE) reactor and reacted at 160 °C for 3 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 Bi / Zn-MOF precursor precipitate was collected.

[0112] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0113] Weigh 0.1g of Bi / Zn-MOF precursor and selenium powder into two ceramic boats at a mass ratio of 1:3. Place the ceramic boat containing selenium powder at the upwind end and calcine it in an argon atmosphere with a heating rate of 10℃ / min until the calcine temperature is reached. 500℃, calcination time 2h Bi2Se3 / ZnSe@NC was collected, and its SEM images are shown below. Figure 14 As shown in the figure, it can be seen that it is an irregular linear structure.

[0114] Example 10

[0115] A method for preparing a Bi2Se3 / ZnSe@NC composite material includes the following steps:

[0116] 1) Preparation of Bi / Zn-MOF precursor:

[0117] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O and 0.243 g of Bi(NO3)3·5H2O were weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The mixture was then transferred to a 50 mL polytetrafluoroethylene (PTFE) reactor and reacted at 160 °C for 3 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 Bi / Zn-MOF precursor precipitate was collected.

[0118] 2) Preparation of Bi2Se3 / ZnSe@NC:

[0119] 0.1 g of Bi / Zn-MOF precursor and selenium powder were weighed and placed in two ceramic boats at a mass ratio of 1:3. The ceramic boat containing selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at a heating rate of 10 °C / min until the calcination temperature reached 700 °C. The calcination time was 2 h. The Bi₂Se₃ / ZnSe@NC mixture was collected, and its SEM image is shown below. Figure 15 As shown.

[0120] Figure 15 It can be seen that the calcination temperature was relatively high when synthesizing Bi2Se3 / ZnSe@NC in Example 10. Although it exhibited a linear structure, some of the structure collapsed due to the excessively high temperature.

[0121] Example 11 (as a comparison)

[0122] A sort of Bi2Se3@NC The method for preparing composite materials includes the following steps:

[0123] 1) Preparation of Bi-MOF precursor:

[0124] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.243 g of Bi(NO3)3·5H2O was weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The mixture was then transferred to a 50 mL polytetrafluoroethylene (PTFE) reactor and reacted at 160 °C for 3 h. After naturally 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 Bi-MOF precursor precipitate was collected.

[0125] 2) Preparation of Bi2Se3@NC:

[0126] 0.1 g of Bi-MOF precursor and selenium powder were weighed and placed in two separate ceramic boats at a mass ratio of 1:3. The boat containing the selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at a heating rate of 10 °C / min until the calcination temperature reached 650 °C. The calcination time was 2 h. Bi₂Se₃@NC was collected, and its SEM image is shown below. Figure 16 As shown in the figure, it can be seen that it has a sheet-like structure, but the size of the sheet-like structure is not uniform.

[0127] Example 12 (as a comparison)

[0128] A sort of ZnSe@NC The method for preparing composite materials includes the following steps:

[0129] 1) Preparation of precursor Zn-MOF:

[0130] 0.125 g of 2-methylimidazole was dispersed in 10.0 mL of glycerol to form a homogeneous solution. 0.149 g of Zn(NO3)2·6H2O was weighed and added to the homogeneous solution, and the mixture was stirred for 12 h at room temperature. The mixture was then transferred to a 50 mL polytetrafluoroethylene (PTFE) reactor and reacted at 160 °C for 3 h. After naturally 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 Zn-MOF precursor precipitate was collected.

[0131] 2) Preparation of ZnSe@NC:

[0132] 0.1 g of Zn-MOF precursor and selenium powder were weighed and placed in two separate ceramic boats at a mass ratio of 1:3. The boat containing the selenium powder was placed upwind. The mixture was calcined in an argon atmosphere at 650 °C for 2 h at a heating rate of 10 °C / min. ZnSe@NC was collected, and its SEM image is shown below. Figure 17 As shown in the figure, it can be seen that it is a blocky structure with a shape similar to a willow leaf.

[0133] Example 13

[0134] An application of Bi2Se3 / ZnSe@NC composite material in sodium-ion batteries, the specific application method is as follows:

[0135] The Bi2Se3 / ZnSe@NC nanowire cluster structure material prepared in Example 1 was used as the active material. It was mixed with conductive carbon black and polyvinylidene fluoride in a ratio of 8:1:1. NMP was added dropwise and the mixture was magnetically stirred for 8 hours to disperse it evenly. The uniformly mixed slurry was coated onto copper foil using a coater and placed in a vacuum drying oven at 80°C. After drying for 24 hours, it was pressed into tablets using a tablet press and then cut into small circular electrode sheets using a cutting machine. The electrode sheets were assembled into button batteries in a glove box filled with high-purity argon gas and with water and oxygen values ​​≤0.01ppm. The electrolyte was NaPF6+DEGDME. The sodium sheet had a purity of Na≥99.99% and a thickness of 0.5mm. After rolling, it was cut to the size of the electrode sheet.

[0136] 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, add 3 drops of electrolyte to the glass fiber and place the sodium plate 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 12 hours.

[0137] Then in 0.2Ag -1 1Ag -1 The cycle performance and charge / discharge performance of the coin cell were tested under the given current, and the results are as follows: Figure 18 , Figure 19 , Figure 20 , Figure 21 As shown in the figure, there is a relatively stable charge / discharge platform and cycle performance.

[0138] The Bi2Se3@NC block structure material prepared in Example 11 was used as the active material. It was mixed with conductive carbon black and polyvinylidene fluoride in a ratio of 8:1:1. NMP was added dropwise and the mixture was magnetically stirred for 8 hours to disperse it evenly. The uniformly mixed slurry was coated onto copper foil using a coater and placed in a vacuum drying oven at 80°C. After drying for 24 hours, it was pressed into tablets using a tablet press and then cut into small circular electrode sheets using a cutting machine. The electrode sheets were assembled into button batteries in a glove box filled with high-purity argon gas and with water and oxygen values ​​≤0.01ppm. The electrolyte was NaPF6+DEGDME. The sodium sheet had a purity of Na≥99.99% and a thickness of 0.5mm. After rolling, it was cut to the size of the electrode sheet.

[0139] 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, add 3 drops of electrolyte to the glass fiber and place the sodium plate 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 12 hours.

[0140] Then in 0.2Ag -1 The cycle performance and charge / discharge performance of the coin cell were tested under the given current, and the results are as follows: Figures 22-23 As shown in the figure, its charge-discharge platform is relatively unstable and its cycle performance is poor.

[0141] The ZnSe@NC block structure material prepared in Example 12 was used as the active material. It was mixed with conductive carbon black and polyvinylidene fluoride in a ratio of 8:1:1. NMP was added dropwise and the mixture was magnetically stirred for 8 hours to disperse it evenly. The uniformly mixed slurry was coated onto copper foil using a coater and placed in a vacuum drying oven at 80°C. After drying for 24 hours, it was pressed into tablets using a tablet press and then cut into small circular electrode sheets using a cutting machine. The electrode sheets were assembled into button batteries in a glove box filled with high-purity argon gas and with water and oxygen values ​​≤0.01ppm. The electrolyte was NaPF6+DEGDME. The sodium sheet had a purity of Na≥99.99% and a thickness of 0.5mm. After rolling, it was cut to the size of the electrode sheet.

[0142] 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, add 3 drops of electrolyte to the glass fiber and place the sodium plate 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 12 hours.

[0143] Then in 0.2Ag -1 The cycle performance and charge / discharge performance of the coin cell were tested under the given current, and the results are as follows: Figures 24-25 As shown in the figure, although it has a stable charge and discharge platform, its cycle stability is poor.

[0144] The data marked with an underline or superscript indicates data that does not meet the requirements of this invention.

[0145] 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 bismuth triselenide / zinc selenide@nitrogen carbon composite material, characterized in that, The preparation method includes the following steps: 1) Disperse zinc source, bismuth source and organic ligand in organic solvent and carry out solvothermal reaction to obtain precursor Bi / Zn-MOF; 2) The precursor Bi / Zn-MOF and selenium powder obtained in step 1) were loaded into a ceramic boat and calcined to obtain a linear Bi2Se3 / ZnSe@NC composite material; In step 1), the solvothermal reaction conditions are 150~190℃ for 2~4 hours; the organic ligand is 2-methylimidazole; In step 2), the calcination conditions are 600~700℃ for 2 hours.

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

3.

3. The preparation method according to claim 1 or 2, characterized in that, The organic solvent is glycerol.

4. The preparation method according to claim 1, characterized in that, In step 2), the mass ratio of the precursor Bi / Zn-MOF to selenium powder is 1:

3.

5. The preparation method according to claim 1, characterized in that, In step 2), calcination is carried out in an argon atmosphere.

6. A bismuth triselenide / zinc selenide@nitrogen carbon composite material prepared by the preparation method according to any one of claims 1-5, characterized in that, In step 1), the solvothermal reaction conditions are 160℃ for 3 h; in step 2), the calcination conditions are 600℃ for 2 h. The resulting bismuth selenide / zinc selenide@nitrogen carbon composite material is a cluster structure composed of nanowires with a length of 4-6 μm and a diameter of 40-50 nm.

7. The application of the bismuth triselenide / zinc selenide@nitrogen carbon composite material according to claim 6 in a sodium-ion battery.

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