Preparation method and material of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material

Abstract

This invention relates to the field of energy storage nanomaterials technology, specifically to a method and material for preparing nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials. The method includes: preparing a basic nickel carbonate / zinc precursor solution, subjecting it to hydrothermal reaction in a reactor, and washing and drying the hydrothermal reaction product to obtain basic nickel carbonate / zinc nanosheets; preparing a 2-methylimidazole solution, placing the basic nickel carbonate / zinc nanosheets in the prepared 2-methylimidazole solution, stirring at room temperature, and then washing and drying to obtain a nickel / zinc metal-organic framework composite material; carbonizing the nickel / zinc metal-organic framework composite material in an inert gas environment; mixing the obtained nickel / zinc@nitrogen-doped carbon composite material with selenium powder and grinding it; and subjecting the ground product to a selenization reaction in a protective gas environment to obtain the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material. This invention can efficiently prepare materials with stable structures and good rate performance for use as anode materials in sodium-ion batteries.

Description

Technical Field

[0001] This invention relates to the field of energy storage nanomaterials technology, and in particular to a method for preparing nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material and the material thereof. Background Technology

[0002] With the continued growth of global energy demand and the rapid development of renewable energy, efficient, reliable, and cost-effective energy storage technologies have become particularly important. Rechargeable lithium-ion batteries have achieved great success in promoting the efficient conversion and convenient utilization of clean energy. However, with the proliferation of lithium battery products and the explosive expansion of market demand, the limited, uneven distribution, and continuously rising prices of lithium resources have restricted their widespread use. Sodium-ion batteries, as a potential alternative, have received widespread attention in recent years due to their abundant resources, low cost, and environmental friendliness. However, sodium-ion batteries still face many challenges in practical applications, particularly the performance optimization of anode materials.

[0003] Studies have shown that transition metal chalcogenides (TMX, X = O, S, Se) have excellent sodium storage properties and can react with sodium, thus possessing a high theoretical specific capacity. Among them, Se has lower electronegativity and higher electronic conductivity than O and S, which is conducive to the rapid transport of ions and electrons and accelerates the diffusion kinetics of sodium ions. However, due to the large sodium ion radius, the electrode material will undergo a drastic volume expansion, resulting in the disadvantages of rapid capacity decay, poor rate performance, and poor cycle stability of transition metal selenides, which seriously restricts the widespread application of transition metal selenides in sodium-ion batteries.

[0004] Therefore, how to provide a simple and efficient preparation method for transition metal selenide anode energy storage materials, while improving the theoretical specific capacity of the materials, rate performance and cycle stability, has become an urgent technical problem to be solved. Summary of the Invention

[0005] In view of this, in order to overcome the shortcomings of the prior art, the present invention provides a method for preparing nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material and the material thereof.

[0006] According to one aspect of the present invention, a method for preparing a nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material is provided, the method comprising:

[0007] Step 1: Preparation of basic nickel carbonate / zinc nanosheets

[0008] A basic nickel carbonate / zinc precursor solution was prepared using nickel nitrate hexahydrate, zinc nitrate hexahydrate, urea, and deionized water in the specified proportions.

[0009] The prepared basic nickel carbonate / zinc precursor solution was placed in a reaction vessel for hydrothermal reaction. The hydrothermal reaction product was washed and dried to obtain basic nickel carbonate / zinc nanosheets.

[0010] Step 2: Preparation of nickel / zinc metal-organic framework composite materials

[0011] A 2-methylimidazole solution was prepared, and basic nickel carbonate / zinc nanosheets were placed in the prepared 2-methylimidazole solution and stirred at room temperature. The stirred product was then washed and dried to obtain a nickel / zinc metal-organic framework composite material.

[0012] Step 3: Preparation of nickel / zinc@nitrogen-doped carbon composite material

[0013] Nickel / zinc metal-organic framework composites were carbonized in an inert gas environment to obtain nickel / zinc@nitrogen-doped carbon composites.

[0014] Step 4: Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material

[0015] Nickel / zinc@nitrogen-doped carbon composite material is mixed with selenium powder according to the specified ratio and then ground. The ground product is subjected to selenization reaction in a protective gas environment to obtain nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material.

[0016] Preferably, in the preparation method of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention, in step one, a basic nickel carbonate / zinc precursor solution is prepared by using nickel nitrate hexahydrate, zinc nitrate hexahydrate, urea and deionized water in a certain ratio, including: when preparing the basic nickel carbonate / zinc precursor solution, each batch contains 2.5 mmol of nickel nitrate hexahydrate, 2.5 mmol of zinc nitrate hexahydrate, 25 mmol of urea and 50 ml of deionized water in a certain ratio.

[0017] Preferably, in the preparation method of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention, in step one, the hydrothermal reaction temperature is 105-135℃ and the hydrothermal reaction time is 10-12h.

[0018] Preferably, in the preparation method of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention, in step one, the hydrothermal reaction product is cleaned and dried to obtain basic nickel carbonate / zinc nanosheets, comprising: sequentially cleaning the hydrothermal reaction product cooled to room temperature with deionized water and anhydrous ethanol, and drying the cleaned product at 80°C for 10 h to obtain basic nickel carbonate / zinc nanosheets.

[0019] Preferably, in the preparation method of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention, step two involves preparing a 2-methylimidazole solution and placing basic nickel carbonate / zinc nanosheets in the prepared 2-methylimidazole solution and stirring at room temperature. This includes: preparing a 2-methylimidazole solution with a concentration of 3-7 mol / L, placing 40 mg of basic nickel carbonate / zinc nanosheets in 3 ml of the prepared 2-methylimidazole solution and stirring at room temperature for 6-24 h.

[0020] Preferably, in the preparation method of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention, step two, in which the stirred product is washed and dried to obtain the nickel / zinc metal-organic framework composite material, includes: washing the stirred product sequentially with deionized water and anhydrous ethanol, and drying the washed product at 80°C for 10 h to obtain the nickel / zinc metal-organic framework composite material.

[0021] Preferably, in the preparation method of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention, step three involves carbonizing the nickel / zinc metal-organic framework composite material in an inert gas environment, including: placing the nickel / zinc metal-organic framework composite material in an argon environment with an argon flow rate of 20 mL / min, heating it to 400-800°C at a heating rate of 2-5°C / min, holding it at that temperature for 2 hours, and then naturally cooling it to room temperature.

[0022] Preferably, in the preparation method of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention, step four involves mixing the nickel / zinc@nitrogen-doped carbon composite material with selenium powder according to the specified ratio and then grinding the mixture, including: mixing 1 part by weight of the nickel / zinc@nitrogen-doped carbon composite material with 2 parts by weight of selenium powder, and grinding the mixed material for 10 minutes.

[0023] Preferably, in the preparation method of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention, step four involves carrying out a selenization reaction on the ground product in a protective gas environment, including: placing the ground product in an argon environment with an argon flow rate of 20 mL / min, heating it to 400-450°C at a heating rate of 2-5°C / min, holding it at that temperature for 2 hours, and then naturally cooling it to room temperature.

[0024] According to another aspect of the present invention, the present invention provides a nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material, which is prepared according to the above method.

[0025] According to another aspect of the present invention, the present invention provides an application of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material as a negative electrode material for sodium-ion batteries.

[0026] The preparation method and material of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention have the following beneficial effects:

[0027] 1. By preparing basic nickel / zinc carbonate nanosheets, their large specific surface area is utilized to transform them into a uniform nickel / zinc metal-organic framework composite material, enhancing structural stability. By introducing nitrogen, the conductivity and electrochemical reactivity of the material are further improved, allowing for the adsorption of more sodium ions, thereby enhancing the material's sodium storage capacity.

[0028] 2. The nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in this invention, when applied to sodium-ion battery anode materials, can increase the theoretical specific capacity of the material and improve its cycle stability and rate performance through a synergistic effect. Secondly, the coating effect of nitrogen-doped porous carbon can significantly improve the conductivity and structural stability of the material, which is beneficial to electrolyte penetration and rapid ion transport. It can also effectively alleviate the volume expansion problem of nickel diselenide and zinc selenide during charge and discharge, thereby extending the cycle life of the battery and improving its performance.

[0029] 3. The preparation method of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention has the characteristics of strong controllability, green and environmentally friendly, simple process, high efficiency and low cost. It can be applied in the manufacturing industry of sodium-ion battery energy storage devices and is conducive to large-scale industrial production. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The image shown is an FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 1 of this invention.

[0032] Figure 2 The image shown is an FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 2 of this invention.

[0033] Figure 3 The image shown is an FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 3 of this invention.

[0034] Figure 4 The image shown is a FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 4 of this invention.

[0035] Figure 5The image shown is an FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 5 of this invention.

[0036] Figure 6 This is a FESEM image of the basic nickel carbonate / zinc nanosheets prepared in Example 4 of this invention;

[0037] Figure 7 The image shown is a FESEM image of the nickel / zinc metal-organic framework composite material prepared in Example 4 of this invention.

[0038] Figure 8 The image shown is a FESEM image of the nickel / zinc@nitrogen-doped carbon composite material prepared in Example 4 of this invention.

[0039] Figure 9 The XRD patterns are of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4 and 5 of this invention.

[0040] Figure 10 Electrochemical rate performance diagrams of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4 and 5 of this invention;

[0041] Figure 11 The nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 4 of this invention was tested at 50 mAg. -1 The first five charge-discharge curves under the current density. Detailed Implementation

[0042] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0043] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0044] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0045] Example 1

[0046] Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials:

[0047] Step 1: Preparation of basic nickel carbonate / zinc nanosheets

[0048] A basic nickel carbonate / zinc precursor solution was prepared by mixing 2.5 mmol nickel nitrate hexahydrate, 2.5 mmol zinc nitrate hexahydrate, 25 mmol urea, and 50 ml deionized water according to the specified ratio. The prepared basic nickel carbonate / zinc precursor solution was placed in a reaction vessel with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 105 °C for 12 h to obtain the hydrothermal reaction product. The hydrothermal reaction product, cooled to room temperature, was washed sequentially with deionized water and anhydrous ethanol. The washed product was then dried at 80 °C for 10 h to obtain basic nickel carbonate / zinc nanosheets.

[0049] Step 2: Preparation of nickel / zinc metal-organic framework composite materials

[0050] A 3 mol / L 2-methylimidazole solution was prepared. 40 mg of basic nickel carbonate / zinc nanosheets were placed in 3 ml of the prepared 2-methylimidazole solution and stirred at room temperature for 24 h. The stirred product was washed with deionized water and anhydrous ethanol in sequence. The washed product was dried at 80 °C for 10 h to obtain the nickel / zinc metal-organic framework composite material.

[0051] Step 3: Preparation of nickel / zinc@nitrogen-doped carbon composite material

[0052] In an argon atmosphere with an argon flow rate of 20 mL / min, the nickel / zinc metal-organic framework composite material was carbonized at 800℃ with a heating rate of 5℃ / min. After holding at this temperature for 2 hours, it was naturally cooled to room temperature to obtain the nickel / zinc@nitrogen-doped carbon composite material.

[0053] Step 4: Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material

[0054] One part by weight of nickel / zinc@nitrogen-doped carbon composite material was mixed with two parts by weight of selenium powder. The mixture was ground for 20 min. The ground product was placed in a ceramic boat in a tube furnace. The furnace was heated to 400°C at a heating rate of 5°C / min in an argon atmosphere with a flow rate of 20 mL / min and held for 2 h. The selenization reaction product was then naturally cooled to room temperature to obtain nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material.

[0055] Example 2

[0056] Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials:

[0057] Step 1: Preparation of basic nickel carbonate / zinc nanosheets

[0058] A basic nickel carbonate / zinc precursor solution was prepared by mixing 2.5 mmol nickel nitrate hexahydrate, 2.5 mmol zinc nitrate hexahydrate, 25 mmol urea, and 50 ml deionized water according to the specified ratio. The prepared basic nickel carbonate / zinc precursor solution was placed in a reaction vessel with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 120°C for 11 h to obtain the hydrothermal reaction product. The hydrothermal reaction product, cooled to room temperature, was washed sequentially with deionized water and anhydrous ethanol. The washed product was then dried at 80°C for 10 h to obtain basic nickel carbonate / zinc nanosheets.

[0059] Step 2: Preparation of nickel / zinc metal-organic framework composite materials

[0060] A 5 mol / L 2-methylimidazole solution was prepared. 40 mg of basic nickel / zinc carbonate nanosheets were placed in 3 ml of the prepared 2-methylimidazole solution and stirred at room temperature for 12 h. The stirred product was washed with deionized water and anhydrous ethanol in sequence. The washed product was dried at 80 °C for 10 h to obtain the nickel / zinc metal-organic framework composite material.

[0061] Step 3: Preparation of nickel / zinc@nitrogen-doped carbon composite material

[0062] In an argon atmosphere with an argon flow rate of 20 mL / min, the nickel / zinc metal-organic framework composite material was carbonized at 700℃ with a heating rate of 4℃ / min. After holding at this temperature for 2 hours, it was naturally cooled to room temperature to obtain the nickel / zinc@nitrogen-doped carbon composite material.

[0063] Step 4: Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material

[0064] One part by weight of nickel / zinc@nitrogen-doped carbon composite material was mixed with two parts by weight of selenium powder. The mixture was ground for 15 min. The ground product was placed in a ceramic boat in a tube furnace. The furnace was heated to 430°C at a heating rate of 4°C / min in an argon atmosphere with a flow rate of 20 mL / min and held for 2 h. The selenization reaction product was then naturally cooled to room temperature to obtain nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material.

[0065] Example 3

[0066] Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials:

[0067] Step 1: Preparation of basic nickel carbonate / zinc nanosheets

[0068] A basic nickel carbonate / zinc precursor solution was prepared by mixing 2.5 mmol nickel nitrate hexahydrate, 2.5 mmol zinc nitrate hexahydrate, 25 mmol urea, and 50 ml deionized water according to the specified ratio. The prepared basic nickel carbonate / zinc precursor solution was placed in a reaction vessel with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 135°C for 10 h to obtain the hydrothermal reaction product. The hydrothermal reaction product, cooled to room temperature, was washed sequentially with deionized water and anhydrous ethanol. The washed product was then dried at 80°C for 10 h to obtain basic nickel carbonate / zinc nanosheets.

[0069] Step 2: Preparation of nickel / zinc metal-organic framework composite materials

[0070] A 7 mol / L 2-methylimidazole solution was prepared. 40 mg of basic nickel carbonate / zinc nanosheets were placed in 3 ml of the prepared 2-methylimidazole solution and stirred at room temperature for 6 h. The stirred product was washed with deionized water and anhydrous ethanol in sequence. The washed product was dried at 80 °C for 10 h to obtain the nickel / zinc metal-organic framework composite material.

[0071] Step 3: Preparation of nickel / zinc@nitrogen-doped carbon composite material

[0072] In an argon atmosphere with an argon flow rate of 20 mL / min, the nickel / zinc metal-organic framework composite material was carbonized at 600℃ with a heating rate of 2℃ / min. After holding at this temperature for 2 hours, it was naturally cooled to room temperature to obtain the nickel / zinc@nitrogen-doped carbon composite material.

[0073] Step 4: Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material

[0074] One part by weight of nickel / zinc@nitrogen-doped carbon composite material was mixed with two parts by weight of selenium powder. The mixture was ground for 10 min. The ground product was placed in a ceramic boat in a tube furnace. The furnace was heated to 400°C at a heating rate of 2°C / min in an argon atmosphere with a flow rate of 20 mL / min. The temperature was held for 2 h. The selenization reaction product was then naturally cooled to room temperature to obtain nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material.

[0075] Example 4

[0076] Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials:

[0077] Step 1: Preparation of basic nickel carbonate / zinc nanosheets

[0078] A basic nickel carbonate / zinc precursor solution was prepared by mixing 2.5 mmol nickel nitrate hexahydrate, 2.5 mmol zinc nitrate hexahydrate, 25 mmol urea, and 50 ml deionized water according to the specified ratio. The prepared basic nickel carbonate / zinc precursor solution was placed in a reaction vessel with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 120°C for 10 h to obtain the hydrothermal reaction product. The hydrothermal reaction product, cooled to room temperature, was washed sequentially with deionized water and anhydrous ethanol. The washed product was then dried at 80°C for 10 h to obtain basic nickel carbonate / zinc nanosheets.

[0079] Step 2: Preparation of nickel / zinc metal-organic framework composite materials

[0080] A 5 mol / L 2-methylimidazole solution was prepared. 40 mg of basic nickel / zinc carbonate nanosheets were placed in 3 ml of the prepared 2-methylimidazole solution and stirred at room temperature for 12 h. The stirred product was washed with deionized water and anhydrous ethanol in sequence. The washed product was dried at 80 °C for 10 h to obtain the nickel / zinc metal-organic framework composite material.

[0081] Step 3: Preparation of nickel / zinc@nitrogen-doped carbon composite material

[0082] In an argon atmosphere with an argon flow rate of 20 mL / min, the nickel / zinc metal-organic framework composite material was carbonized at 500℃ with a heating rate of 2℃ / min. After holding at this temperature for 2 hours, it was naturally cooled to room temperature to obtain the nickel / zinc@nitrogen-doped carbon composite material.

[0083] Step 4: Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material

[0084] One part by weight of nickel / zinc@nitrogen-doped carbon composite material was mixed with two parts by weight of selenium powder. The mixture was ground for 10 minutes. The ground product was placed in a ceramic boat in a tube furnace. The furnace was heated to 450°C at a heating rate of 2°C / min in an argon atmosphere with a flow rate of 20 mL / min. The temperature was held for 2 hours. The selenization reaction product was then naturally cooled to room temperature to obtain nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material.

[0085] Example 5

[0086] Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials:

[0087] Step 1: Preparation of basic nickel carbonate / zinc nanosheets

[0088] A basic nickel carbonate / zinc precursor solution was prepared by mixing 2.5 mmol nickel nitrate hexahydrate, 2.5 mmol zinc nitrate hexahydrate, 25 mmol urea, and 50 ml deionized water according to the specified ratio. The prepared basic nickel carbonate / zinc precursor solution was placed in a reaction vessel with a polytetrafluoroethylene liner for hydrothermal reaction at a temperature of 120°C for 10 h to obtain the hydrothermal reaction product. The hydrothermal reaction product, cooled to room temperature, was washed sequentially with deionized water and anhydrous ethanol. The washed product was then dried at 80°C for 10 h to obtain basic nickel carbonate / zinc nanosheets.

[0089] Step 2: Preparation of nickel / zinc metal-organic framework composite materials

[0090] A 5 mol / L 2-methylimidazole solution was prepared. 40 mg of basic nickel / zinc carbonate nanosheets were placed in 3 ml of the prepared 2-methylimidazole solution and stirred at room temperature for 12 h. The stirred product was washed with deionized water and anhydrous ethanol in sequence. The washed product was dried at 80 °C for 10 h to obtain the nickel / zinc metal-organic framework composite material.

[0091] Step 3: Preparation of nickel / zinc@nitrogen-doped carbon composite material

[0092] In an argon atmosphere with an argon flow rate of 20 mL / min, the nickel / zinc metal-organic framework composite material was carbonized at 400℃ with a heating rate of 2℃ / min. After holding at this temperature for 2 hours, it was naturally cooled to room temperature to obtain the nickel / zinc@nitrogen-doped carbon composite material.

[0093] Step 4: Preparation of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material

[0094] One part by weight of nickel / zinc@nitrogen-doped carbon composite material was mixed with two parts by weight of selenium powder. The mixture was ground for 10 minutes. The ground product was placed in a ceramic boat in a tube furnace. The furnace was heated to 450°C at a heating rate of 2°C / min in an argon atmosphere with a flow rate of 20 mL / min. The temperature was held for 2 hours. The selenization reaction product was then naturally cooled to room temperature to obtain nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material.

[0095] Example 6

[0096] The microstructures of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4, and 5, and the basic nickel carbonate / zinc nanosheets, nickel / zinc metal-organic framework composite materials, and nickel / zinc@nitrogen-doped carbon composite materials prepared in Example 4 were observed using a thermal field emission scanning electron microscope (FESEM) manufactured by Zeiss AG, Germany. The experimental procedures and parameters included: the materials prepared in each example were made into powder samples, and the samples were attached to the sample stage with conductive adhesive and observed using the instrument. The accelerating voltage was 5 kV.

[0097] The microstructure of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 1 is shown in [reference needed]. Figure 1 The magnification is 100,000 times; the microstructure of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 2 is shown in [reference needed]. Figure 2 The magnification is 100,000 times; the microstructure of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 3 is shown in [reference needed]. Figure 3 The magnification is 100,000 times; the microstructure of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 4 is shown in [reference needed]. Figure 4 The magnification is 100,000 times; the microstructure of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 5 is shown in [reference needed]. Figure 5 The magnification is 100,000 times; the microstructure of the basic nickel carbonate / zinc nanosheets prepared in Example 4 is shown in [reference needed]. Figure 6 The magnification is 100,000 times; the microstructure of the nickel / zinc metal-organic framework composite material prepared in Example 4 is shown in [reference needed]. Figure 7 The magnification is 100,000 times; the microstructure of the nickel / zinc@nitrogen-doped carbon composite material prepared in Example 4 is shown in [reference needed]. Figure 8 The magnification is 100,000 times.

[0098] Figure 1 The image shown is a FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 1 of this invention. Figure 1 As shown, the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material is composed of nickel diselenide and zinc selenide nanoparticles and nitrogen-doped porous carbon. After carbonization and selenization reaction, the surface is relatively rough and has a large specific surface area, which increases the number of active sites, which is conducive to the adsorption of sodium ions and helps to improve the capacity of sodium-ion batteries.

[0099] Figure 2 The image shown is a FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 2 of this invention. Figure 2As shown, by adjusting the concentration of the 2-methylimidazole solution, the surface of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material after carbonization and selenization is rougher and has a larger specific surface area. When the material is used as the negative electrode material of sodium-ion battery, it is beneficial to the insertion of more sodium ions and thus improves the capacity of sodium-ion battery.

[0100] Figure 3 The image shown is a FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 3 of this invention. Figure 3 As shown, by adjusting the temperature and time of hydrothermal treatment, the distribution of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material after carbonization and selenization is more uniform, and the number of nickel diselenide and zinc selenide nanoparticles increases. When the material is used as a negative electrode material for sodium-ion batteries, it is beneficial for the rapid insertion and extraction of sodium ions, which is conducive to improving the first coulombic efficiency of sodium-ion batteries.

[0101] Figure 4 The image shown is a FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 4 of this invention. Figure 4 As shown, a large number of nickel diselenide and zinc selenide nanoparticles are attached to the carbon skeleton. When the material is used in the anode material of sodium-ion batteries, the presence of the carbon skeleton helps to alleviate the volume expansion caused by electrochemical charging and discharging. The heterostructure formed by nickel diselenide and zinc selenide helps to improve the specific capacity of the electrode material.

[0102] Figure 5 The image shown is a FESEM image of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 5 of this invention. Figure 5 As shown, by adjusting the temperature of the carbonization process, the original dodecahedral structure becomes more prominent, resulting in a more uniform distribution of nickel diselenide and zinc selenide nanoparticles formed by the subsequent selenization reaction. When the material is applied to the anode material of sodium-ion batteries, it is beneficial for the insertion and extraction of sodium ions, and helps to improve the structural stability of sodium-ion batteries during the electrochemical reaction process.

[0103] Figure 6 The image shown is a FESEM image of the basic nickel carbonate / zinc nanosheets prepared in Example 4 of this invention. Figure 6 As shown, the basic nickel carbonate / zinc nanosheets are uniform in size and do not exhibit agglomeration, which is beneficial for subsequent processes to prepare nickel / zinc metal-organic framework composite materials with uniform size.

[0104] Figure 7 The image shown is a FESEM image of the nickel / zinc metal-organic framework composite material prepared in Example 4 of this invention. Figure 7As shown, the nickel / zinc metal-organic framework composite material exhibits a regular dodecahedral structure with clustered nanoparticles attached to its surface. The particle size distribution is relatively uniform, providing a stable structure for subsequent processes. When the material is applied to the anode material of sodium-ion batteries, it is beneficial to enhance the structural stability during the electrochemical reaction process.

[0105] Figure 8 The FESEM image of the nickel / zinc@nitrogen-doped carbon composite material prepared in Example 4 of this invention is shown below. Figure 8 As shown, after high-temperature carbonization, the original dodecahedral structure shrinks to form a stable carbon skeleton, which enhances the structural stability of the material. Furthermore, nickel / zinc nanoparticles are attached to the surface, which further enhances the conductivity of the material.

[0106] Example 7

[0107] The phase composition of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4, and 5 was analyzed using an XRD-6000 (3KW) XRD instrument manufactured by Shimadzu Corporation, Japan. The experimental procedure and parameter settings included: placing the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in each example into a glass slide groove (2.0*2.0cm), ensuring the groove was completely filled, and then placing it in the XRD instrument. The X-ray source was Cu target Kα rays (λ=0.15418nm), the scanning range was 10-80°, the scanning rate was 4° / min, the tube voltage was 40kV, and the tube current was 30mA. The test results are shown in [reference needed]. Figure 9 .

[0108] Figure 9 The XRD patterns of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4, and 5 of this invention are shown below. Figure 9 As shown, the XRD patterns of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4 and 5 correspond to the standard PDF cards NiSe2-JCPDS#88-1711 and ZnSe-JCPDS#88-2345, indicating that the materials prepared in Examples 1, 2, 3, 4 and 5 contain nickel diselenide and zinc selenide.

[0109] Example 8

[0110] The nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4, and 5 were mixed with conductive agent Super P and polyvinylidene fluoride respectively in a mass ratio of 8:1:1 and stirred evenly to obtain a mixed product. Then, N-methylpyrrolidone was added to the mixed product as a solvent and stirred evenly to obtain a slurry with suitable viscosity. Finally, the slurry was coated onto a copper foil with a thickness of 9 μm using an SZQ type four-sided preparation device (thickness of 150 μm) produced by Tianjin Jinghai District Kexin Testing Machine Factory. The coated copper foil was vacuum dried at 80℃ for 12 h to obtain the electrode sheet made of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Examples 1, 2, 3, 4, and 5.

[0111] The nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite electrode sheets prepared in Examples 1, 2, 3, 4, and 5 were cut into sheets using a tablet press manufactured by Shenzhen Kejing Materials Technology Co., Ltd. The experimental process and parameters included: cutting the materials prepared in each example into 12mm diameter circular sheets as electrode materials; using a CR2025 battery casing and 1M NaCF3SO3 in… Diglyme (100%) electrolyte, glass fiber separator, and sodium metal sheet were placed together in a glove box with a water and oxygen content of less than 0.1 ppm. The electrode material was placed in the center of the positive electrode shell, and two drops of electrolyte were added to fully wet the electrode material. Then, the glass fiber separator was covered onto the electrode sheet with tweezers. The sodium metal sheet, gasket, spring sheet, and negative electrode shell were then placed in sequence. Finally, the battery was sealed using a battery sealing machine of model PX-HS-20 produced by Shenzhen Kejing Materials Technology Co., Ltd., to obtain a sodium-ion battery composed of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Examples 1, 2, 3, 4, and 5 as the negative electrode material.

[0112] Electrochemical tests were conducted on sodium-ion batteries assembled from nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4, and 5 using a CT3002A Blue Electric Battery Testing System manufactured by Wuhan Blue Electric Electronics Co., Ltd. The experimental procedures and parameters included: current densities of 0.05 Ag... -1 0.1Ag -1 0.2A g -1 0.5Ag -1 1.0Ag -1 2.0Ag -1 5.0Ag -1 and 10.0Ag -1The electrochemical performance of each embodiment was reflected by constant current charge-discharge testing.

[0113] Figure 10 The electrochemical rate performance diagrams are shown for the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4, and 5 of this invention. Figure 10 As shown, the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1, 2, 3, 4 and 5 have good sodium storage performance, and the charge and discharge capacity overlap is high under different current densities, with the efficiency maintained at around 100%.

[0114] Figure 11 The sodium-ion battery assembled from the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in Example 4 of this invention operates at 50 mAg. -1 The first five charge-discharge curves under current density, with the first charge cycle showing a capacity of 576.80 mAh g. -1 The discharge capacity is 588.43 mAh g. -1 The efficiency in the first lap was as high as 98.02%.

[0115] Sodium-ion batteries assembled using nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1 to 5 achieved a performance of 50 mAg. -1 The first charge-discharge capacity and first coulombic efficiency under current density are shown in Table 1.

[0116] Table 1

[0117]

[0118] As can be seen from Table 1, the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite materials prepared in Examples 1-5 of this invention exhibit excellent electrochemical performance when used as anode materials for sodium-ion batteries. Among them, the anode material prepared in Example 4 shows particularly good performance at 50 mAg. -1 The initial charge-discharge specific capacity under current density testing was 576.80 / 588.43 mAh g. -1 The initial coulombic efficiency is as high as 98.02%, and the other embodiments all have high charge-discharge specific capacity, with initial coulombic efficiencies all above 95%.

[0119] The preparation method and material of the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention have the following beneficial effects:

[0120] 1. By preparing basic nickel / zinc carbonate nanosheets, their large specific surface area is utilized to transform them into a uniform nickel / zinc metal-organic framework composite material, enhancing structural stability. By introducing nitrogen, the conductivity and electrochemical reactivity of the material are further improved, allowing for the adsorption of more sodium ions, thereby enhancing the material's sodium storage capacity.

[0121] 2. The nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material prepared in this invention, when applied to sodium-ion battery anode materials, can increase the theoretical specific capacity of the material and improve its cycle stability and rate performance through a synergistic effect. Secondly, the coating effect of nitrogen-doped porous carbon can significantly improve the conductivity and structural stability of the material, which is beneficial to electrolyte penetration and rapid ion transport. It can also effectively alleviate the volume expansion problem of nickel diselenide and zinc selenide during charge and discharge, thereby extending the cycle life of the battery and improving its performance.

[0122] 3. The preparation method of nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material of the present invention has the characteristics of strong controllability, green and environmentally friendly, simple process, high efficiency and low cost. It can be applied in the manufacturing industry of sodium-ion battery energy storage devices and is conducive to large-scale industrial production.

[0123] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material, characterized in that, The method includes: Prepare a basic nickel carbonate / zinc precursor solution by mixing 2.5 mmol of nickel nitrate hexahydrate, 2.5 mmol of zinc nitrate hexahydrate, 25 mmol of urea, and 50 ml of deionized water. The prepared basic nickel carbonate / zinc precursor solution was placed in a reaction vessel for hydrothermal reaction at a temperature of 105-135℃ for 10-12 hours. The hydrothermal reaction product was then washed and dried to obtain basic nickel carbonate / zinc nanosheets. Prepare a 3-7 mol / L 2-methylimidazole solution, place 40 mg of basic nickel / zinc carbonate nanosheets in 3 ml of the prepared 2-methylimidazole solution and stir at room temperature for 6-24 h. Wash and dry the product after stirring to obtain nickel / zinc metal-organic framework composite material. The nickel / zinc metal-organic framework composite material was placed in an argon atmosphere with an argon flow rate of 20 mL / min and heated to 400-800℃ at a heating rate of 2-5℃ / min. After holding at this temperature for 2 hours, it was naturally cooled to room temperature to obtain the nickel / zinc@nitrogen-doped carbon composite material. One part by weight of nickel / zinc@nitrogen-doped carbon composite material was mixed with two parts by weight of selenium powder and ground for 10 min. The ground product was placed in an argon atmosphere with an argon flow rate of 20 mL / min and heated to 400-450℃ at a heating rate of 2-5℃ / min. After holding at this temperature for 2 h, it was naturally cooled to room temperature to obtain nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material.

2. The method for preparing the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material according to claim 1, characterized in that, The hydrothermal reaction product was cleaned and dried to obtain basic nickel carbonate / zinc nanosheets. The process included: cleaning the hydrothermal reaction product cooled to room temperature with deionized water and anhydrous ethanol in sequence, and drying the cleaned product at 80°C for 10 h to obtain basic nickel carbonate / zinc nanosheets.

3. The method for preparing the nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material according to claim 1, characterized in that, The product after stirring is washed and dried to obtain a nickel / zinc metal-organic framework composite material, including: washing the product after stirring with deionized water and anhydrous ethanol in sequence, and drying the washed product at 80°C for 10 h to obtain the nickel / zinc metal-organic framework composite material.

4. A nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material, characterized in that, The nickel diselenide@zinc selenide / nitrogen-doped porous carbon composite material is prepared by the method according to any one of claims 1 to 3.

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