Preparation method and application of porous nickel diselenide nanowire

Abstract

The invention discloses a preparation method and application of a porous nickel diselenide nanowire, and relates to the field of energy storage material preparation and performance research, the preparation process is as follows: firstly, under the condition of no template and surfactant, a soluble nickel salt and an alkali mixture are subjected to a hydrothermal reaction to obtain a precursor nickel hydroxide nanowire; and then under the protection of inert gas, performing heat treatment on the precursor by using selenium powder to obtain the nickel diselenide nanowire with a porous structure. The preparation method disclosed by the invention is simple and easy to implement, does not need a template, a surfactant and complex equipment, and is low in cost; the prepared nickel diselenide nanowire has a porous structure, has a large specific surface area, and has a wide application prospect in the fields of energy storage, catalysis and the like. The prepared porous nickel diselenide nanowire is used as a supercapacitor electrode material, shows large specific capacity, good rate capability and excellent cycling stability, and is a supercapacitor positive electrode material with application prospects.

Description

Technical Field

[0001] The invention relates to the field of energy storage material preparation and performance research, and in particular to a preparation method and application of multi-porous nickel diselenide nanowires. Background Art

[0002] Nowadays, green and efficient energy storage and conversion systems have attracted much attention. Among various power devices, supercapacitors have become a dazzling member with their outstanding advantages such as high specific power, fast charging and discharging speed, low manufacturing and maintenance costs, and long service life. However, the practical application of supercapacitors is severely limited due to insufficient energy density. It is well known that electrode materials play a key role in providing significant energy storage capacity. In order to provide sufficient energy density while maintaining power density and long service life, it is urgent to develop advanced electroactive materials and broaden the operating voltage of supercapacitors.

[0003] In order to achieve high-performance energy storage, people have tried to use various transition metal compounds such as metal selenides, oxides, sulfides, hydroxides, etc. as positive electrode materials for supercapacitors. Oxygen, sulfur, and selenium belong to Group VI A and have some similar properties. Compared with oxides and sulfides, transition metal selenides have smaller band gaps and higher conductivity. Therefore, they are expected to provide higher specific capacity and excellent energy storage performance in supercapacitors. Among them, NiSe 2 It has a low band gap (0.1eV), a small resistivity (<10 -3 Ω / cm) and good metallic properties, so it is a promising advanced supercapacitor material. 2 As electrode materials for supercapacitors. For example, Arul and his collaborators prepared hexagonal NiSe by hydrothermal method. 2 At 1mA / cm 2 Under current conditions, hexagonal NiSe 2 Available in 75F g -1 The specific capacity of NiS 2 NiSe synthesized using hollow spheres as precursor 2 hollow spheres, which can provide a specific capacitance of 341 F / g at 1 A / g. Chang et al. prepared NiSe containing Se vacancies using a plasma-assisted dry exfoliation strategy. 2 Nanosheets, with a specific capacity of 466F / g at 3A / g. Pyramidal NiSe 2 Used to construct all-solid-state NiSe 2 / / AC asymmetric supercapacitor, the device is 1.60mW / cm 2 The energy density at a power of 0.196mWh / cm 2Although some remarkable achievements have been made, most of the NiSe-based 2 The materials used in this study all have the problems of insufficient accessible surface and poor cycle durability. Optimizing the synthesis path and exploring new process methods are crucial to the successful synthesis of NiSe. 2 It is crucial to promote electrode materials to practical applications. An effective strategy is to construct porous nanowires with rich pores, which have the following advantages: 1) The rich pore structure is conducive to electrolyte wetting and ion diffusion, thereby obtaining high specific capacity and excellent rate performance. 2) Nanopores can play the role of "storage" and buffer space, which can resist the stress during continuous charge and discharge, thus helping to improve the cycle life. Therefore, the controlled synthesis of NiSe with rich nanopores is a good choice. 2 Nanowires are a promising strategy. In addition, assembling asymmetric capacitors can further improve the operating voltage and specific capacitance, thereby achieving high energy density storage. Therefore, it is necessary to provide a preparation method and application of multi-porous nickel diselenide nanowires to solve the above problems. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a preparation method and application of multi-porous nickel diselenide nanowires. Compared with metal oxides and sulfides, metal selenides have higher conductivity, which is beneficial to improve rate performance. Multi-porous nanowires have a large specific surface area, can provide abundant electrode / electrolyte interface contact and buffer space, and are beneficial to provide high specific capacity and cycle life. Therefore, the synthesis of NiSe with abundant nanopores is controlled. 2 Nanowires, as supercapacitor electrode materials, are a promising strategy. In addition, assembling asymmetric capacitors can further broaden the operating voltage, thereby achieving high energy density energy storage, so the following technical solutions are provided:

[0005] A method for preparing multi-porous nickel diselenide nanowires comprises the following steps:

[0006] Step 1, dissolving a soluble nickel salt in water, then adding alkali, stirring evenly, to obtain a mixed solution;

[0007] Step 2: hydrothermally treat the mixture at 120° C. for 24 hours; after the reaction is completed, naturally cool to room temperature, centrifuge, wash, and dry to obtain nickel hydroxide nanowires;

[0008] Step 3, weigh a certain amount of selenium powder and nickel hydroxide nanowires, put them into two crucibles respectively, and then place the selenium powder in the upper airflow of the tube furnace and the nickel hydroxide nanowires in the lower airflow position of the tube furnace;

[0009] Step 4: First, pass inert gas through the tube furnace, remove air, and then continue to ventilate;

[0010] Step 5: Heat the tube furnace from room temperature to 350° C. under the protection of inert gas and keep the temperature for a period of time. After the reaction is completed, cool it to room temperature to obtain black porous nickel diselenide nanowires.

[0011] In the step 1, the soluble nickel salt is one of nickel sulfate, nickel nitrate or nickel acetate, and the base is one of nickel hydroxide or potassium hydroxide.

[0012] In step three, the mass ratio of selenium powder to nickel hydroxide nanowires is 4:1 to 1:4.

[0013] In the step 4, the flow rate of the inert gas is 20 to 60 mL / min.

[0014] In the step 5, the heating rate is 1-5°C / min, and the insulation time is 1-2h.

[0015] The present invention also discloses a method for preparing multi-porous nickel diselenide nanowires and an application of the prepared multi-porous nickel diselenide nanowires in preparing supercapacitors, including electrode preparation and performance testing, and the method is as follows:

[0016] (1) Electrode preparation: First, porous nickel diselenide nanowires, acetylene black and PVDF were weighed in a mass ratio of 80:10:10, and NMP was added to prepare a slurry. The slurry was then coated on nickel foam, which was placed in a vacuum drying oven and dried at 80°C for 12 h. After drying, it was pressed into a thin sheet as a working electrode;

[0017] (2) Three-electrode test of capacitance performance: A three-electrode system was formed with a porous nickel diselenide nanowire electrode as the working electrode, a Hg / HgO electrode as the reference electrode, a Pt sheet electrode as the counter electrode, and a 4.0 mol / L KOH solution as the electrolyte. Cyclic voltammetry and constant current charge-discharge techniques were used to study the capacitance performance of the electrode.

[0018] (3) An asymmetric supercapacitor was assembled using porous nickel diselenide nanowire electrode as the positive electrode, activated carbon electrode as the negative electrode, and 4.0 mol / L KOH solution as the electrolyte. The energy storage performance of the capacitor was studied using cyclic voltammetry and constant current charge and discharge techniques.

[0019] Beneficial effects of the invention: Beneficial effects of the invention:

[0020] 1. The multi-porous nickel diselenide nanowires prepared by the present invention have a large specific surface area, can expose more active sites, improve specific capacity and electrochemical kinetics, and can be applied to supercapacitors with high energy density;

[0021] 2. The multi-porous nickel diselenide nanowires prepared by the present invention have a linear structure and abundant pores, which are beneficial to electrolyte wetting and ion diffusion, thereby obtaining a high specific capacity and excellent rate performance.

[0022] 3. The multi-porous nickel diselenide nanowires prepared by the present invention can play the role of "storage" and buffer space, which can resist the stress during continuous charge and discharge, thereby improving the cycle stability.

[0023] 4. The preparation process of the present invention is simple, the conditions are mild, the operation is easy, no surfactants, templates and complex equipment are required, the cost is low, the morphology of the product is controllable, and it is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The multi-porous nickel diselenide nanowire (NiSe 2 -200) TEM photo;

[0025] Figure 2 XRD patterns of nickel hydroxide nanowires and multi-porous nickel diselenide nanowires prepared in Examples 1-3;

[0026] Figure 3 CV graphs of nickel hydroxide nanowires and multi-porous nickel diselenide nanowires prepared in Examples 1-3;

[0027] Figure 4 GCD curves of nickel hydroxide nanowires and multi-porous nickel diselenide nanowires prepared in Examples 1-3 at a current density of 1 A / g;

[0028] Figure 5 NiSe prepared in Example 2 2 -200 Assembled NiSe 2 -200 / / CV graphs of AC asymmetric supercapacitors at different scan rates;

[0029] Figure 6 NiSe prepared in Example 2 2 -200 Assembled NiSe 2 -200 / / GCD curve of AC asymmetric supercapacitor at 1 A / g current density.

[0030] Figure 7 NiSe prepared in Example 2 2 -200 Assembled NiSe 2 -200 / / Lagung plot of AC asymmetric supercapacitor. DETAILED DESCRIPTION

[0031] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0032] Example 1

[0033] A preparation method and application of multi-porous nickel diselenide nanowires:

[0034] Step 1: dissolve 2.579 g of nickel sulfate hexahydrate in 40.0 ml of water, then add 0.196 g of sodium hydroxide and stir evenly to obtain a mixed solution;

[0035] Step 2: hydrothermally treat the mixture at 120°C for 24 hours; after the reaction is completed, naturally cool to room temperature, centrifuge, wash, and dry to obtain green nickel hydroxide nanowires;

[0036] Step 3, weigh 100 mg of selenium powder and 100 mg of nickel hydroxide nanowires, put them into two crucibles respectively, and then place the selenium powder in the upper airflow of the tube furnace and the nickel hydroxide nanowires in the lower airflow position of the tube furnace;

[0037] Step 4: First, evacuate the tube furnace with argon for 20 minutes, and then continue to ventilate at a flow rate of 40.0 ml / min;

[0038] Step 5: Heat the temperature of the tube furnace from room temperature to 350°C at a heating rate of 2°C / min under argon protection, and keep it at 350°C for 2 hours. After the reaction is completed, cool it to room temperature to obtain black multi-porous nickel diselenide nanowires marked as NiSe 2 -100.

[0039] Example 2

[0040] The difference from Example 1 is that the mass of selenium powder in step 3 is 200 mg, and the other conditions and steps are the same, and the obtained black multi-porous nickel diselenide nanowires are marked as NiSe 2 -200.

[0041] Example 3

[0042] The difference from Example 1 is that the mass of selenium powder in step 3 is 300 mg, and the other conditions and steps are the same, and the obtained black multi-porous nickel diselenide nanowires are marked as NiSe 2 -300.

[0043] XRD patterns of nickel hydroxide nanowires and porous nickel diselenide nanowires Figure 2 All diffraction peaks of nickel hydroxide nanowires can be indexed as Ni(SO 4 ) 0.3 (OH) 1.4The diffraction peaks of (JCPDS No.41-1424) indicate that pure phase α-Ni(OH) 2 .Diffraction peaks of porous nickel diselenide nanowires prepared under different selenium powder quality conditions and cubic phase NiSe 2 The diffraction peaks of (JCPDS No.41-1495) correspond one to one.

[0044] NiSe 2 -200 TEM photos such as Figure 1 As shown in the figure, it can be seen that nickel diselenide nanowires have a linear structure and a rich pore structure, which is conducive to electrolyte wetting and ion diffusion. The nanopores can play the role of "storage" and buffer space, which can resist the stress during the charging and discharging process, thereby obtaining excellent energy storage performance.

[0045] Electrochemical energy storage performance test: The nickel hydroxide nanowires (α-Ni(OH) 2 ) and porous nickel diselenide nanowires (NiSe 2 -100, NiSe 2 -200 and NiSe 2 -300) was made into a test electrode, and the lithium sheet was used as the counter electrode. The electrochemical capacitance performance of the electrode was first tested by the three-electrode method, and then the activated carbon was used as the negative electrode, and NiSe 2 -200 is NiSe for positive electrode assembly 2 -200 / / AC asymmetric supercapacitor, energy storage performance test in the potential range of 0-1.7V.

[0046] The specific steps are as follows: (1) firstly, porous nickel diselenide nanowires or nickel hydroxide nanowires, acetylene black and PVDF are weighed in a mass ratio of 80:10:10, and a proper amount of NMP is added to prepare a slurry, and then the slurry is coated on nickel foam, which is placed in a vacuum drying oven and dried at 80°C for 12 h. After drying, it is pressed into a thin sheet as a working electrode;

[0047] (2) Three-electrode test of capacitance performance: A three-electrode system was formed using porous nickel diselenide nanowire electrode or nickel hydroxide nanowire electrode as the working electrode, Hg / HgO electrode as the reference electrode, Pt sheet electrode as the counter electrode, and 4.0 mol / L KOH solution as the electrolyte. The capacitance performance of the electrode was studied using cyclic voltammetry (potential range: 0-0.7 V) and constant current charge and discharge (potential range: 0-0.5 V) techniques.

[0048] (3) NiSe 2 -200 electrode as positive electrode, AC electrode as negative electrode, 4.0mol / L KOH solution as electrolyte, assembled NiSe 2-200 / / AC asymmetric supercapacitor, using cyclic voltammetry, constant current charge and discharge (potential range: 0-1.7V) and other technologies to study the energy storage performance of the capacitor.

[0049] Figure 3 The CV curves of the four electrodes at a scan rate of 20 mV / s are shown in Figure 2. Figure 3 It can be seen that there is a pair of obvious redox peaks on each CV curve, indicating that nickel hydroxide nanowires and multi-porous nickel diselenide nanowires are both battery-type electrode materials. 2 The area enclosed by the CV curve of the -200 electrode is the largest, indicating that NiSe 2 The -200 electrode has the largest specific capacitance.

[0050] Figure 4 is the GCD curve of the four electrodes at a current density of 1A / g. Figure 4 It can be seen that each GCD curve has a nonlinear structure and a distinct charge-discharge platform, which further indicates that nickel hydroxide nanowires and multi-porous nickel diselenide nanowires are both battery-type electrode materials. 2 The discharge time of -200 electrode is the longest, indicating that NiSe 2 -200 electrode has the largest specific capacitance. At a current density of 1A / g, α-Ni(OH) 2 、NiSe 2 -100, NiSe 2 -200 and NiSe 2 The discharge specific capacities of -300 are 563.2, 868.6, 1123.8 and 959.6 F / g respectively.

[0051] Figure 5 For NiSe 2 -200 / / AC asymmetric supercapacitor CV curves at different scan rates. The CV curves are rectangular and have obvious redox peaks, which indicates that NiSe 2 -200 / / AC asymmetric supercapacitors rely not only on the double layer but also on redox reactions to store charge. The shape of the CV curves did not change significantly with increasing scan rates, indicating that NiSe 2 -200 / / AC asymmetric supercapacitors have excellent stability.

[0052] Figure 6 For NiSe 2 -200 / / GCD curves of AC asymmetric supercapacitors at different current densities. Figure 6 As shown in the figure, the GCD curves at different current densities are almost triangular symmetrical, which indicates that NiSe 2-200 / / AC asymmetric supercapacitors have ideal capacitance characteristics. NiSe 2 -200 / / AC asymmetric supercapacitor has a specific capacity of 88.3F / g at a current density of 1.0A / g.

[0053] like Figure 7 NiSe 2 -200 / / AC asymmetric supercapacitor Ragon diagram. NiSe 2 -200 / / AC asymmetric supercapacitor can provide 35.4Wh / kg specific energy at 850W / kg power density. Even if the specific power is increased to 8500W / kg, NiSe2-200 / / AC asymmetric supercapacitor can still produce 22.6Wh / kg specific energy, indicating that NiSe 2 -200 / / AC asymmetric supercapacitor has excellent energy storage performance.

[0054] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A method for preparing porous nickel diselenide nanowires, It is characterized in that The steps include: Step 1, dissolving a soluble nickel salt in water, then adding alkali, stirring evenly, to obtain a mixed solution; Step 2: hydrothermally treat the mixture at 120° C. for 24 hours; after the reaction is completed, naturally cool to room temperature, centrifuge, wash, and dry to obtain nickel hydroxide nanowires; Step 3, weigh a certain amount of selenium powder and nickel hydroxide nanowires, put them into two crucibles respectively, and then place the selenium powder in the upper airflow of the tube furnace and the nickel hydroxide nanowires in the lower airflow position of the tube furnace; Step 4: First, pass inert gas through the tube furnace, remove air, and then continue to ventilate; Step 5: Heat the tube furnace from room temperature to 350° C. under the protection of inert gas and keep the temperature for a period of time. After the reaction is completed, cool it to room temperature to obtain black porous nickel diselenide nanowires.

2. A method for preparing multi-porous nickel diselenide nanowires according to claim 1, Features: In the step 1, the soluble nickel salt is one of nickel sulfate, nickel nitrate or nickel acetate, and the base is one of nickel hydroxide or potassium hydroxide.

3. A method for preparing multi-porous nickel diselenide nanowires according to claim 1, Features: In step three, the mass ratio of selenium powder to nickel hydroxide nanowires is 4:1 to 1:

4.

4. A method for preparing multi-porous nickel diselenide nanowires according to claim 1, Features: In the step 4, the flow rate of the inert gas is 20 to 60 mL / min.

5. A method for preparing multi-porous nickel diselenide nanowires according to claim 1, Features: In the step 5, the heating rate is 1-5°C / min, and the insulation time is 1-2h.

6. Application of the multi-porous nickel diselenide nanowires prepared by the method for preparing multi-porous nickel diselenide nanowires according to any one of claims 1 to 5, It is characterized in that Applied to the preparation of supercapacitors, including electrode preparation and performance testing, the method is as follows: (1) Electrode preparation: First, porous nickel diselenide nanowires, acetylene black and PVDF were weighed in a mass ratio of 80:10:10, and NMP was added to prepare a slurry. The slurry was then coated on nickel foam, which was placed in a vacuum drying oven and dried at 80°C for 12 h. After drying, it was pressed into a thin sheet as a working electrode; (2) Three-electrode test of capacitance performance: A three-electrode system was formed with a porous nickel diselenide nanowire electrode as the working electrode, a Hg / HgO electrode as the reference electrode, a Pt sheet electrode as the counter electrode, and a 4.0 mol / L KOH solution as the electrolyte. Cyclic voltammetry and constant current charge-discharge techniques were used to study the capacitance performance of the electrode. (3) An asymmetric supercapacitor was assembled using porous nickel diselenide nanowire electrode as the positive electrode, activated carbon electrode as the negative electrode, and 4.0 mol / L KOH solution as the electrolyte. The energy storage performance of the capacitor was studied using cyclic voltammetry and constant current charge and discharge techniques.

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