WO2021012397A1 - Method for preparing nickel cobaltate porous material, and use thereof - Google Patents

Abstract

Provided is a method for preparing a nickel cobaltate porous material, comprising the following steps: adding a compound containing a cobalt ion, a compound containing a nickel ion, and a compound containing a sodium ion into an organic solvent, and adding a precipitant, so as to obtain a mixed solution; subjecting the resulting mixed solution to an ultrasonic treatment and then heating same; and cooling the heated mixed solution and then calcining same, so as to produce a uniform nickel cobaltate porous material. The material can be used as an electrode material of a super capacitor to effectively increase the electricity storage capacity of the super capacitor, and can also be used as a negative electrode material of a rechargeable lithium ion battery.

Description

Preparation method and application of nickel cobaltate porous material Technical field

The invention belongs to the field of electrode materials and electrochemistry, and relates to a negative electrode material for lithium ion batteries, in particular to a preparation method and application of a nickel cobaltate porous material.

Background technique

my country began to develop supercapacitors in the 1980s and listed them as a national research topic. Supercapacitors not only have the two major advantages of high power density and high energy density, but also have the advantages of fast charging speed, long cycle life, rich electrode materials and environmental protection. As a new type of energy storage component, supercapacitors have amazing product value and huge market potential in transportation vehicles (especially electric or hybrid vehicles and special transportation vehicles), electricity, computers, communications, and military. Although the current level of my country's supercapacitor industry has not reached the forefront of the world, the research in the field of supercapacitors has reached the world's leading level. The core component of a supercapacitor is the electrode, and the electrode material is a key factor in determining the performance of the supercapacitor. Therefore, the development of supercapacitor electrode materials with high electrochemical performance has become the hottest topic in research.

Theoretically, Co ₃ O ₄ has the highest specific capacitance among transition metal oxides and is an excellent material for preparing supercapacitor electrodes, and its preparation method is not complicated. However, Co ₃ O ₄ is more expensive and more expensive than other transition metals. There is also toxicity. Therefore, through the research of cobalt oxide materials, it has become a research direction to develop materials that are similar in structure to Co ₃ O ₄ , have little functional difference, are cheaper and are environmentally friendly. NiCo ₂ O ₄ is a spinel phase AB ₂ O ₄ type composite oxide. Nickel ions occupy octahedral positions, and cobalt ions occupy both octahedral and tetrahedral positions. In terms of its physical structure, NiCo ₂ O _{4 The} material is very similar to Co ₃ O _4. NiCo ₂ O ₄ itself has two redox counter ions, Ni ²⁺ and Ni ³⁺ , Co ²⁺ and Co ³⁺ , so compared to NiO and Co ₃ O ₄ , NiCo ₂ O ₄ itself has good conductivity. In addition, NiCo ₂ O _{4 has} better electrochemical properties than Co ₃ O ₄ , low production cost, and sufficient raw materials. Therefore, research and preparation of high-performance nickel cobalt oxide materials is of great significance.

Summary of the invention

In view of the above technical problems in the prior art, the present invention provides a method for preparing a high-performance nickel cobalt oxide porous material to improve the electrode performance of a lithium battery.

The invention provides a method for preparing a nickel cobaltate porous material, which comprises the following steps:

Add the compound containing cobalt ion, the compound containing nickel ion, the compound containing sodium ion to the organic solvent, and the precipitation agent is added to obtain a mixed solution;

The obtained mixed solution is ultrasonically treated and then heated;

The heated mixed solution is cooled and then calcined to obtain a nickel cobaltate porous material.

Preferably, the compound containing cobalt ions is one or more of cobalt nitrate, cobalt carbonate and cobalt sulfate; the compound containing nickel ions is one or more of nickel nitrate, nickel carbonate and nickel sulfate; containing sodium ions The compound is one or more of sodium nitrate, sodium carbonate, sodium bicarbonate and sodium sulfate.

More preferably, the cobalt nitrate is cobalt nitrate hexahydrate; the nickel nitrate is nickel nitrate hexahydrate.

Preferably, the organic solvent is polyethylene glycol; the precipitation agent is urea.

More preferably, the polyethylene glycol is polyethylene glycol 400.

Preferably, the mass ratio of polyethylene glycol 400, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, sodium nitrate, and urea is (300-500): (40-60): (20-40): 1: (100 -200). More preferably, the mass ratio of polyethylene glycol 400, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, sodium nitrate, and urea is (400-500): (50-60): (25-35):1: ( 100-150).

Preferably, the obtained mixed solution is subjected to ultrasonic treatment, and the ultrasonic time is 20-120 minutes. More preferably, the ultrasound time is 30-90 minutes.

Preferably, the ultrasonic mixed solution is heated, the heating temperature is 80-100° C., and the heating time is 1-4 hours. More preferably, the heating temperature is 90-100°C, and the heating time is 2-3 hours.

Preferably, the heated mixed solution is cooled and then roasted, the roasting temperature is 300-600°C, and the roasting time is 4-8 hours. More preferably, the heating rate is 2-3°C per minute.

Specifically, the preparation method of the nickel cobaltate porous material adopts the hydrothermal method and includes the following steps:

Measure 30-50mL polyethylene glycol 400 in a beaker, weigh 4-6g cobalt nitrate hexahydrate, 2-4g nickel nitrate hexahydrate, and 0.08-0.1g sodium nitrate into the beaker, stir slowly to disperse in the polyethylene two In the alcohol, then weigh 10-20g of urea into the beaker;

Ultrasound the resulting solution for 20-120 minutes, then heat the resulting solution to 80-100°C and stir for 1-4 hours under constant temperature conditions;

After the reaction, the solution is taken out and cooled to room temperature, heated to 300-600°C under the condition of contact with air, at a heating rate of 2-3°C per minute, and calcined for 4-8 hours;

After cooling, a black solid is obtained, which is ground to obtain a nickel cobaltate porous material.

More specifically, the preparation method of the nickel cobaltate porous material adopts the hydrothermal method and includes the following steps:

Measure 40-50mL polyethylene glycol 400 in a beaker, weigh 5-6g cobalt nitrate hexahydrate, 2.5-3.5g nickel nitrate hexahydrate, and 0.08-0.1g sodium nitrate into the beaker, stir slowly to disperse in the polyethylene In the glycol, then weigh 10-15g of urea into the beaker;

Ultrasound the resulting solution for 30-90 minutes, and then heat the resulting solution to 90-100°C and stir for 2-3 hours under constant temperature conditions;

After the reaction, the solution was taken out and cooled to room temperature, and heated to 400°C under the condition of contact with air, at a heating rate of 2-3°C per minute, and calcined for 6 hours;

After cooling, a black solid is obtained, which is ground to obtain a nickel cobaltate porous material.

The invention also provides the application of the prepared nickel cobalt oxide porous material. The nickel cobalt oxide prepared by the method of the invention is suitable for serving as a negative electrode material for lithium ion batteries and super capacitors, and effectively improves the storage performance of the super capacitor.

The structure of the porous nickel cobalt oxide material obtained in the present invention is studied by scanning electron microscope (SEM), and its electrochemical performance is tested. The results show that the present invention has the following beneficial effects:

(1) The crystal grains of the product obtained by the preparation method of the present invention can reach about ten nanometers, indicating that the preparation method of the present invention can prepare nano-scale nickel cobalt oxide materials, and the prepared materials are very uniform. During the experiment, we used urea as the precipitant and sodium nitrate as the auxiliary agent to increase the specific surface area of the nickel cobaltate product. From the scanning electron microscope test photos, the material is spinel, and the uneven surface makes the material The specific surface area has increased a lot. Supercapacitor electrode materials have the advantage of large specific surface area, which can better generate redox reactions, so that supercapacitors provide higher energy storage.

(2) The supercapacitor device made of the nickel cobalt oxide material obtained by the preparation method of the present invention has certain energy storage and stable and rapid charging and discharging functions, and the specific capacitance is close to 30F/g.

Description of the drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, together with the embodiments of the present invention, are used to explain the present invention, and do not constitute a limitation to the present invention.

Fig. 1 is a scanning electron microscope test photograph of a porous nickel cobalt oxide material prepared according to Example 2 under 10,000 times.

Fig. 2 is a scanning electron microscope test photograph of the porous nickel cobalt oxide material prepared according to Example 3 at 10000 times.

FIG. 3 is a cyclic voltammetry curve diagram of a supercapacitor device made of the nickel cobalt oxide porous material obtained in Example 2. FIG.

Detailed ways

The present invention will now be further described in conjunction with specific examples. The following examples are intended to illustrate the present invention but not to further limit the present invention.

Example 1

A preparation method of nickel cobaltate porous material, weigh 50mL polyethylene glycol 400 into a beaker, weigh 5.8g cobalt nitrate hexahydrate, 2.9g nickel nitrate hexahydrate, and 0.09g sodium nitrate into the beaker, slowly stir to make it Disperse in polyethylene glycol 400, then weigh 10g of urea into a beaker, use an ultrasonic cleaner to perform ultrasound for 1 hour, then put the resulting solution in an oil bath, heat to 100°C, and react with constant temperature stirring for 2 hours. The stirring speed is 300r/min; After the reaction, the solution was taken out and cooled to room temperature, transferred to a square crucible, placed in a muffle furnace in contact with air, first heated to 300°C for 2 hours at a constant temperature, and then heated to 400 Treat it at a constant temperature of ℃ for 6 hours, the heating rate is 2-3 ℃ per minute, wait until it is cooled to obtain a black solid, grind with a grinder to finally obtain a porous nickel cobaltate material.

Example 2

A method for preparing nickel cobaltate porous material. Measure 45mL polyethylene glycol 400 in a beaker, weigh 5.8g cobalt nitrate hexahydrate, 2.9g nickel nitrate hexahydrate, and 0.1g sodium nitrate into the beaker, and slowly stir to make it Disperse in polyethylene glycol 400, then weigh 15g of urea into a beaker, use an ultrasonic cleaner to perform ultrasound for 1 hour, then put the resulting solution in an oil bath and heat to 100°C, and react with magnetic stirring for 2 hours at a stirring speed of 300r /min: After the reaction, the solution is taken out and cooled to room temperature, transferred to a square crucible, and placed in a muffle furnace in contact with air, heated to 300°C for 2 hours, and then heated to 400°C Constant temperature treatment for 6 hours at a rate of temperature increase of 2-3°C per minute. After cooling, a black solid is obtained, which is then ground with a grinder to obtain a nickel cobaltate porous material.

Example 3

A preparation method of nickel cobaltate porous material, weigh 40mL polyethylene glycol 400 in a beaker, weigh 5.8g cobalt nitrate hexahydrate, 2.9g nickel nitrate hexahydrate, and 0.1g sodium nitrate into the beaker, slowly stir to make it Disperse in polyethylene glycol 400, then weigh 15g of urea into a beaker, use an ultrasonic cleaner for ultrasound for 1 hour, then put the resulting solution in an oil bath and heat to 100°C, magnetically stir for 2 hours, and stir at 330r /min: After the reaction, the solution is taken out and cooled to room temperature, transferred to a square crucible, placed in a muffle furnace in contact with air, and directly heated to 400°C for 6 hours at a constant temperature at a heating rate of 2-3 ℃ per minute, let it cool to obtain a black solid, grind it with a grinder to finally obtain a porous nickel cobaltate material.

Referring to Figure 1 and Figure 2, it can be seen by scanning electron microscopy that the crystal grains of the nickel cobalt oxide material thus produced can reach about ten nanometers, indicating that the preparation method of the experiment can obtain nano-scale nickel cobalt oxide material, and the preparation The material is very uniform. During the experiment, the present invention uses urea as the precipitant and sodium nitrate as the auxiliary agent to increase the specific surface area. From the scanning electron microscope test photos, the material is spinel, and the uneven surface makes the material The specific surface area has increased a lot. In addition, it can be seen from the comparison between Fig. 1 and Fig. 2 that the calcination temperature has a certain influence on the particle size and surface area of the material. The test also verified that NiCo ₂ O ₄ as a supercapacitor electrode material has the advantage of large specific surface area, so that it can better undergo redox reactions, so that the prepared supercapacitors can provide higher energy storage.

Example 4

In this example, an electrochemical test was performed on the NiCo ₂ O ₄ powder prepared in Example 2

Preparation of Super Capacitor Test Device

Cut a 1cm×2cm carbon cloth, and then put it in a beaker soaked in absolute ethanol. Place the beaker in an ultrasonic cleaning machine for ultrasonic cleaning with a proper water level for 1 hour to remove impurities attached to the carbon cloth. After washing, put the carbon cloth into a dry glass petri dish, put it in an electric thermostatic blast drying box and dry at 80°C for 30 minutes, then take it out, let it cool to room temperature, and brush a layer on one side of the carbon cloth with liquid glue. Cut oily paper that is slightly larger than the carbon cloth, stick it on the glue, and cut off the sides. Use another glass petri dish to press the carbon cloth pasted with oily paper into the electric heating constant temperature blast drying box and dry it at 80℃ for 30 minutes, then take it out. Then brush a thin layer of glue on the oily paper to prepare 0.02g NiCo _{Spread the 2} O ₄ powder evenly on the glue and push it flatly with a glass rod to make the powder evenly distributed, then put it in an electric thermostatic blast drying oven and dry at 80°C for 1 hour, then take it out, cool to room temperature, and cut out two pieces of 1cm×1cm copper foil , Distributed on the carbon cloth and powder layer, and then welded wires on the copper foil for testing.

Cyclic Voltammetry

The cyclic voltammetry test method is to control the initial potential loaded on the working electrode and conduct it at a certain scanning rate. One cycle consists of two parts: forward scanning and reverse scanning to complete a charge and discharge process. The different potentials enable the materials on the working electrode in the electrolyte to produce different degrees of redox reactions, which are recorded by the current-potential curve, which is the cyclic voltammetry curve. The curve can reflect the redox reversibility of the electrode material and electrochemical properties such as capacitance. The scanning speed of the cyclic voltammetry test is between 10-100mV/s, and the C-V curve change law under different scanning rates is measured. The voltage window for the charge and discharge experiment is -0.6-0.4V.

Suppose the scan rate is k, then the discharge scan speed is -k, S1 and S2 are the projected areas of the discharge curve and the charge curve on the horizontal axis, respectively, assuming that the charge capacitance and the discharge capacitance are equal.

For the discharge curve

-mkC=I(U)

(U2-U1)mkC=S1

Similarly charging curve

(U2-U1)mkC=S2

Subtract the two to get

S is the figure enclosed by the cyclic voltammetry curve

A complete CV curve is equivalent to a charge and discharge process, so the cycle integral area should be divided by 2 to be the discharge part. If the mass of the active material is the total mass on the two electrodes, the capacitor capacitance = integral area/(2×scanning speed × potential difference × total active material), the material single electrode is 4 times of the capacitor, that is, the single electrode capacitance = 2 × integral area/(scanning speed × potential difference × total active material).

Refer to FIG. 3, which is a cyclic voltammetry curve diagram of a supercapacitor device made of the nickel cobalt oxide porous material obtained in Example 2. It can be seen from the figure that the cyclic voltammetry curve has a pair of obvious redox peaks. The shape of the curve shows that the capacitance characteristics of this test device are obviously different from that of the electric double layer capacitor. The shape of the cyclic voltammetry curve of the electric double layer capacitor is generally close For the ideal rectangle. The data is processed by Origin software and the area integral of the curve is 69.2240, and the capacitance of the test device is calculated to be 0.5769F and the specific capacitance is 28.84F/g. Through the electrochemical performance test, it is verified that the supercapacitor device made of the nickel cobalt oxide porous material obtained by the present invention has certain energy storage and stable and rapid charge and discharge functions.

Claims (8)

1. A preparation method of nickel cobaltate porous material is characterized in that it comprises the following steps:

   Add the compound containing cobalt ion, the compound containing nickel ion, the compound containing sodium ion to the organic solvent, and the precipitation agent is added to obtain a mixed solution;

   The obtained mixed solution is ultrasonically treated and then heated;

   The heated mixed solution is cooled and then calcined to obtain a nickel cobaltate porous material.
2. The method for preparing nickel cobalt oxide porous material according to claim 1, wherein the compound containing cobalt ions is one or more of cobalt nitrate, cobalt carbonate and cobalt sulfate; the compound containing nickel ions is nickel nitrate One or more of nickel carbonate and nickel sulfate; the compound containing sodium ions is one or more of sodium nitrate, sodium carbonate, sodium bicarbonate and sodium sulfate; organic solvent is polyethylene glycol; precipitating agent For urea.
3. The method for preparing nickel cobaltate porous material according to claim 2, wherein the cobalt nitrate is cobalt nitrate hexahydrate; the nickel nitrate is nickel nitrate hexahydrate; and the polyethylene glycol is polyethylene glycol 400.
4. The method for preparing nickel cobalt oxide porous material according to claim 3, wherein the mass ratio of polyethylene glycol 400, cobalt nitrate hexahydrate, nickel nitrate hexahydrate, sodium nitrate, and urea is (300-500) : (40-60): (20-40): 1: (100-200).
5. The method for preparing a nickel cobaltate porous material according to claim 1, wherein the obtained mixed solution is subjected to ultrasonic treatment for 20-120 minutes; then, constant temperature heating is performed, and the heating temperature is 80-100°C. The heating time is 1-4 hours.
6. The method for preparing nickel cobaltate porous material according to claim 1, wherein the heated mixed solution is cooled and then roasted, the roasting temperature is 300-600°C, the roasting time is 4-8 hours, and the heating rate is 2-3°C per minute.
7. The porous nickel cobalt oxide material prepared by the method of any one of claims 1-6.
8. The application of the nickel cobaltate porous material of claim 7 in the negative electrode material of a rechargeable lithium ion battery.

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