CN115064391A

CN115064391A - Preparation method of electrode material applied to asymmetric supercapacitor

Info

Publication number: CN115064391A
Application number: CN202210572390.4A
Authority: CN
Inventors: 冯婷婷; 焦浩宇; 吴孟强; ***
Original assignee: Yangtze River Delta Research Institute of UESTC Huzhou
Current assignee: Yangtze River Delta Research Institute of UESTC Huzhou
Priority date: 2022-05-25
Filing date: 2022-05-25
Publication date: 2022-09-16
Anticipated expiration: 2042-05-25
Also published as: CN115064391B

Abstract

The invention provides a preparation method of an electrode material applied to an asymmetric supercapacitor. The invention discloses a preparation method of an electrode material applied to an asymmetric supercapacitor, which comprises the following steps: 1) dissolving zinc nitrate hexahydrate and cobalt nitrate hexahydrate in water, and uniformly stirring and mixing to obtain a mixed solution A; 2) taking the mixed solution as electrostatic spinning solution, and obtaining a polymer diaphragm matrix by adopting an electrostatic spinning method; 3) and (3) dropwise adding the mixed solution A obtained in the step (1) into the solution B obtained in the step (2), fully stirring and uniformly mixing, standing for 24 hours, performing suction filtration and separation, and washing with water and ethanol to obtain a precipitate MOF.

Description

Preparation method of electrode material applied to asymmetric supercapacitor

Technical Field

The invention relates to the technical field of super capacitors, in particular to a preparation method of an electrode material applied to an asymmetric super capacitor.

Background

The amount of fossil energy resources represented by petroleum resources is in a growing shortage, and environmental pollution caused by the fossil energy resources is becoming serious, so that the problems force countries to search new energy resources which can be continuously developed and more advanced energy storage technologies. However, various new clean energy sources such as wind power generation and photovoltaic power generation have randomness and uncontrollable characteristics, and obvious production peaks and valleys often exist in practical application, and although considerable progress is made in recent years, fossil energy systems cannot be completely replaced. For 'peak clipping and valley filling', flexible access of clean energy to the power grid is realized, and stable supply of energy by means of energy storage facilities is the best solution at present.

The super capacitor is a novel energy storage device between an electrolytic capacitor and a battery. Compared with the traditional capacitor, the super capacitor has larger specific capacity and higher energy density; supercapacitors have higher power densities and longer cycle lives than rechargeable batteries. The advantages of the super capacitor enable the super capacitor to have wide application prospects, for example, a module group formed by large-capacity super capacitor monomers is applied to cold start assistance of an engine of a heavy truck, a power battery hybrid assembly of a large-sized electric vehicle, an energy heat exchanger of rail transit and the like.

Although supercapacitors do not have a long history of energy density, the development of high capacity electrode materials suitable for use in supercapacitors is still of great interest for increasing the capacity in their operating state. Thus, the concept of asymmetric supercapacitors has been proposed, which is characterized by replacing one side electrode with an electrode material having a similar cell behavior (known as pseudocapacitance) compared to conventional double layer electrochemical supercapacitors. Currently, the commonly used pseudocapacitive materials include transition metal compounds, alloys, conductive polymers, etc., wherein the transition metal compounds, especially the mono-or multi-component oxides and sulfides of metals such as Mn, Co, Ni, Zn, etc., are most concerned. One method for preparing a transition metal compound material with excellent performance is to obtain a composite derivative material of a carbon skeleton and an oxide by starting from an MOF material template with a specific structure and performing high-temperature pyrolysis. There are many studies on MOF derivative materials, but the achieved capacity is still far lower than the theoretical capacity, so there is still a need to further improve the electrochemical performance of the materials by appropriate means.

Disclosure of Invention

The invention aims to provide a preparation method of an electrode material applied to an asymmetric supercapacitor aiming at the defects in the background art. The electrode material provided by the invention adopts a composite structure of an MOF-based metal oxide material and a metal sulfide material, and the oxide material serving as a matrix is subjected to chemical etching, so that the potential of sulfide is also exerted on the basis of improving the performance of the electrode material.

In order to realize the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of an electrode material applied to an asymmetric supercapacitor comprises the following steps:

step 1, dissolving zinc nitrate hexahydrate and cobalt nitrate hexahydrate in water, and uniformly stirring and mixing to obtain a mixed solution A;

step 2, dissolving 2-methylimidazole in water, and uniformly stirring and mixing to obtain a solution B;

step 3, dropwise adding the mixed liquor A obtained in the step 1 into the solution B obtained in the step 2, fully stirring and uniformly mixing, standing for 24 hours, performing suction filtration and separation, and cleaning with water and ethanol to obtain a precipitate MOF;

step 4, mixing the MOF obtained in the step 3 with a tannic acid solution, standing for a period of time, separating by using a differential centrifugation method, and cleaning solids by using water and ethanol to obtain a precursor in the mixture;

step 5, calcining the precursor obtained in the step 4 in an argon atmosphere, and annealing in air to obtain a transition metal oxide material;

and 6, dispersing the transition metal oxide material obtained in the step 5, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, thioacetamide and polyvinylpyrrolidone K40(PVP K40) in a solution of water and glycol, mixing, performing hydrothermal reaction, and performing suction filtration to obtain a solid-phase product, namely the final product.

Compared with the prior art, the invention has the following beneficial effects:

the electrode material applied to the asymmetric supercapacitor is simple and easy to obtain and low in price, and the preparation method is simple;

the composite material structure constructed after basic modification of the electrode material applied to the asymmetric supercapacitor provided by the invention effectively improves the discharge specific capacity under the three-electrode test.

Drawings

FIG. 1 is a three-electrode charge/discharge test curve of the electrodes prepared in comparative examples 1 to 2 and examples 1 to 4;

FIG. 2 is a specific capacity comparison curve of the electrodes prepared in comparative examples 1 to 2 and examples 1 to 4;

fig. 3 is an SEM photograph of the electrode material prepared in example 4.

Detailed Description

The preparation process of the test pole piece adopted in the embodiment and the comparative example of the invention is as follows: fully and uniformly mixing 80 wt% of electrode material of an embodiment or a comparative example, 10 wt% of conductive carbon black and 10 wt% of PVDF, adding N-methylpyrrolidone, and uniformly stirring to obtain electrode slurry; and then, uniformly coating the obtained slurry on foamed nickel, drying, rolling and cutting to obtain the test pole piece.

The electrode plates prepared in the embodiments and the comparative examples of the invention are tested by a three-electrode method, the working electrode adopts a stainless steel electrode clamp to clamp the test electrode plate, the counter electrode adopts a platinum plate electrode, the reference electrode adopts an HgO electrode, and the electrolyte adopts 100mL of 3mol/L potassium hydroxide aqueous solution to perform electrochemical test in a glass sealed electrolytic cell.

The following provides a more detailed description of the implementation of the object of the present invention by means of the drawings and the embodiments.

Step 1, dissolving zinc nitrate hexahydrate with the concentration of 0.1mol/L and cobalt nitrate hexahydrate with the concentration of 0.2mol/L in water, and uniformly stirring and mixing to obtain 30mL of mixed solution A;

step 2, dissolving 2-methylimidazole with the concentration of 0.4g/ml in water, and uniformly stirring and mixing to obtain 30ml of solution B;

step 3, pumping the mixed solution A obtained in the step 1 into the solution B obtained in the step 2 by using a peristaltic pump at the speed of 1.5rpm, fully stirring and uniformly mixing, standing for 24 hours, performing suction filtration and separation, and cleaning with water and ethanol to obtain a precipitate MOF;

step 4, mixing the MOF obtained in the step 3 with 30mL of tannic acid solution with the concentration of 10g/L, standing for a period of time, separating by using a differential centrifugation method, washing solids with water and ethanol to obtain a precursor in the mixture, adding the MOF with the mass of 0.1g, and standing for 0< t < 30 minutes; the rotation speed for separation by the differential centrifugation method is 12000rpm, and the time is 5 minutes;

step 5, calcining the precursor obtained in the step 4 in an argon atmosphere, and annealing in air to obtain a transition metal oxide material, wherein the calcining temperature in the argon atmosphere is 600 ℃, the heat preservation time is 2h, the heating rate is 3 ℃/min, and the gas flow rate is 60 mL/min; the annealing temperature in the air is 300 ℃, the heat preservation time is 2h, and the heating rate is 2 ℃/min;

and 6, dispersing the transition metal oxide material obtained in the step 5, 50mg of nickel nitrate hexahydrate, 100mg of cobalt nitrate hexahydrate, 50mg of thioacetamide and 5mg of polyvinylpyrrolidone K40(PVP K40) in a solution of water and ethylene glycol, mixing, carrying out hydrothermal reaction, and carrying out suction filtration to obtain a solid-phase product, namely a final product, wherein the dosage of the transition metal oxide material is 50mg, and the ratio of water to ethylene glycol is 3:1 total 60mL of mixed solution; the temperature of the hydrothermal reaction is 150 ℃, and the heat preservation time is 5 h.

According to the specific implementation of

steps

4 and 6, the samples obtained are differentiated as described in table 1:

sample(s)	Standing time in step 4	Whether or not to perform step 6
			Example 1	10	Is that
Example 2	20	Is that
			Comparative example 1	0 (skip step 4)	Whether or not
Comparative example 2	10	Whether or not
			Comparative example 3	20	Whether or not
Comparative example 4	0 (skip step 4)	Is that

TABLE 1 differentiation of examples from comparative examples

The specific capacities of the test electrodes prepared in comparative examples 1 to 4 and examples 1 to 2 were tested as follows:

after the test electrodes and relevant elements of the electrolytic cell are configured, the electrochemical workstation CHI660E is connected to carry out testing by a chronoamperometry, the test voltage range is 0-0.55V, and the test current density gradients are 1A/g, 2A/g, 3A/g, 5A/g, 8A/g and 10A/g, and the results are shown in figure 1.

The results of FIG. 1 were further collated to obtain FIG. 2. It can be seen that comparative example 2, which was subjected to the etching treatment in step 4, has a comparable capacity improvement as compared to comparative example 1, which indicates that the treatment by tannic acid etching is effective in improving the electrochemical performance of MOF derivatives. And NiCo from step 6 ₂ S ₄ The compounding work further enhanced the performance of the material, as shown in examples 1, 2 and 4, which were etched for 20 minutes and mixed with NiCo ₂ S ₄ Composite example 2 exhibited the highest specific capacity. The specific data obtained from the electrochemical tests are shown in table 2.

TABLE 2 Capacity of examples and comparative examples in F/g

FIG. 3 is an SEM photograph of example 2. NiCo grown on MOF derivatives can be seen ₂ S ₄ The clustering proves the above conclusion

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. A preparation method of an electrode material applied to an asymmetric supercapacitor is characterized by comprising the following steps: the method comprises the following steps:

step 5, calcining the precursor obtained in the step 4 in an argon atmosphere, naturally cooling the precursor, annealing the precursor in the air, and cooling the cooled precursor to obtain a transition metal oxide material;

and 6, dispersing the transition metal oxide material obtained in the step 5, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, thioacetamide and polyvinylpyrrolidone K40(PVP K40) in a solution of water and glycol, mixing, carrying out hydrothermal reaction, cooling after the reaction is finished, and carrying out suction filtration to obtain a solid-phase product, namely the final product.

2. The preparation method of the electrode material applied to the asymmetric supercapacitor is characterized in that: in the step 1, the concentration of the zinc nitrate hexahydrate in the aqueous solution is 0.1mol/L, and the concentration of the cobalt nitrate hexahydrate in the aqueous solution is 0.2 mol/L.

3. The preparation method of the electrode material applied to the asymmetric supercapacitor is characterized in that: in the step 2, the concentration of the 2-methylimidazole in the aqueous solution is 0.4 g/ml.

4. The preparation method of the electrode material applied to the asymmetric supercapacitor is characterized in that: in step 3, the mixed solution A is added into the solution B by using a peristaltic pump, the pumping rate is 1mL/s, and the ratio of the total added mixed solution A to the solution B is 1:1 according to the volume ratio.

5. The preparation method of the electrode material applied to the asymmetric supercapacitor is characterized in that: in the step 4, the concentration of the tannic acid solution is 10g/L, the MOF prepared in the step 3 is added into the tannic acid solution, the dosage is that 0.1g of MOF is added into every 30mL of the tannic acid solution, and the standing time is more than 0 t and less than or equal to 30 minutes; the speed of rotation used for the differential centrifugation is 12000rpm, and the time is 5-10 minutes.

6. The preparation method of the electrode material applied to the asymmetric supercapacitor is characterized in that: in the step 5, the calcining condition of the argon atmosphere is that the temperature is heated from room temperature to 500-fold sand 700 ℃ at the heating rate of 3 ℃/min, then the heat preservation time is 2-5h, and the flow rate of argon gas in the heating and heat preservation process is 60 mL/min; the annealing in the air is carried out under the conditions that the temperature is heated from room temperature to 350 ℃ at the heating rate of 2 ℃/min, and the heat preservation time is 2-5 h.

7. The preparation method of the electrode material applied to the asymmetric supercapacitor is characterized in that: in step 6, the transition metal oxide material, the nickel nitrate hexahydrate, the cobalt nitrate hexahydrate, the thioacetamide and the PVP K40 are dissolved in a solution obtained by mixing water and ethylene glycol according to the volume ratio of 3:1, wherein the mass ratio of the transition metal oxide material to the nickel nitrate hexahydrate to the cobalt nitrate hexahydrate to the thioacetamide to the PVP K40 is 10:10:20:10: 1; the hydrothermal reaction is carried out at the temperature of 140 ℃ and 160 ℃ and the heat preservation time is 5-12 h.