阅读说明：本技术 一种氢氧化镍纳米阵列/碳布电极材料及其制备方法 (Nickel hydroxide nano array/carbon cloth electrode material and preparation method thereof ) 是由 吴牧宸 支明佳 洪樟连 于 2021-07-01 设计创作，主要内容包括：本发明公开了一种氢氧化镍纳米阵列/碳布电极材料及其制备方法,该制备方法包括：S1：将清洗干燥后的碳布放入浓硝酸和浓硫酸组成的第一溶液中,随后进行活化处理,清洗后得到活化碳布；S2：将活化碳布浸没于第二溶液,得到混合体系；所述第二溶液为六水合硝酸镍溶于无水乙醇所得；将所述混合体系利用无水乙醇进行超临界干燥,得到氢氧化镍纳米阵列/碳布电极材料。通过上述方法制备的氢氧化镍纳米阵列/碳布电极材料具有优异的电化学性能和机械稳定性,可应用于超级电容器。(The invention discloses a nickel hydroxide nano array/carbon cloth electrode material and a preparation method thereof, wherein the preparation method comprises the following steps: s1: putting the cleaned and dried carbon cloth into a first solution consisting of concentrated nitric acid and concentrated sulfuric acid, then carrying out activation treatment, and cleaning to obtain activated carbon cloth; s2: immersing the activated carbon cloth in the second solution to obtain a mixed system; the second solution is obtained by dissolving nickel nitrate hexahydrate in absolute ethyl alcohol; and carrying out supercritical drying on the mixed system by using absolute ethyl alcohol to obtain the nickel hydroxide nano array/carbon cloth electrode material. The nickel hydroxide nano array/carbon cloth electrode material prepared by the method has excellent electrochemical performance and mechanical stability, and can be applied to a super capacitor.)

1. A preparation method of a nickel hydroxide nano array/carbon cloth electrode material is characterized by comprising the following steps:

s1: putting the cleaned and dried carbon cloth into a first solution consisting of concentrated nitric acid and concentrated sulfuric acid, then carrying out activation treatment, and cleaning to obtain activated carbon cloth;

s2: immersing the activated carbon cloth in the second solution to obtain a mixed system; the second solution is obtained by dissolving nickel nitrate hexahydrate in absolute ethyl alcohol; and carrying out supercritical drying on the mixed system by using absolute ethyl alcohol to obtain the nickel hydroxide nano array/carbon cloth electrode material.

2. The method for preparing a nickel hydroxide nanoarray/carbon cloth electrode material as claimed in claim 1, wherein the step S1 is as follows:

and cleaning the carbon cloth with ethanol, acetone and water, drying, putting into the first solution, then putting under a 3V potential together for activation treatment, and cleaning the activated carbon cloth with water to remove impurities to obtain the activated carbon cloth.

3. The method for preparing a nickel hydroxide nanoarray/carbon cloth electrode material according to claim 1 or 2, wherein the volume ratio of concentrated nitric acid to concentrated sulfuric acid in the first solution is 1: 1.

4. the method for preparing a nickel hydroxide nanoarray/carbon cloth electrode material as claimed in claim 1, wherein the concentration of nickel nitrate hexahydrate in the second solution is 0.01-0.5M.

5. The method for preparing the nickel hydroxide nano array/carbon cloth electrode material according to claim 1, wherein the supercritical drying process of the mixed system is performed in a supercritical reaction kettle, and specifically comprises the following steps:

heating the supercritical reaction kettle to 265 ℃ at the heating rate of 5 ℃/min, wherein the pressure reaches 7MPa, so that the absolute ethyl alcohol in the supercritical reaction kettle reaches the supercritical point and changes from a liquid state to a gaseous state; after the reaction is carried out for 1h, discharging the ethanol gas in the supercritical reaction kettle, introducing nitrogen, and then cooling to room temperature to finish the supercritical drying process.

6. The method for preparing the nickel hydroxide nano array/carbon cloth electrode material according to claim 1 or 5, wherein the mixed system is placed in a glass culture dish, and the glass culture dish is placed in a supercritical reaction kettle containing absolute ethyl alcohol for supercritical drying.

7. The method for preparing a nickel hydroxide nano array/carbon cloth electrode material as claimed in claim 6, wherein the liquid level of the absolute ethyl alcohol is lower than the top of the glass culture dish to prevent the absolute ethyl alcohol from submerging the mixed system.

8. The method for preparing a nickel hydroxide nanoarray/carbon cloth electrode material as claimed in claim 1 or 5, wherein the absolute ethanol in the supercritical reactor occupies three-quarters of the volume of the supercritical reactor.

9. The nickel hydroxide nano array/carbon cloth electrode material obtained by the preparation method of any one of claims 1 to 8, wherein the fiber structure of the carbon cloth is completely retained, and microstructure stability is shown; the nickel hydroxide nanosheets uniformly grow on the carbon cloth and completely cover the carbon cloth, so that a three-dimensional porous network-shaped layered structure is formed.

Technical Field

The invention belongs to the technical field of preparation of electrode materials of supercapacitors, and particularly relates to a nickel hydroxide nano-array/carbon cloth electrode material and a preparation method thereof.

Background

Transition metal oxides, hydroxides, and sulfides have been extensively studied as efficient pseudocapacitive materials. Among the numerous hydroxides, Ni (OH)₂Has the characteristics of low cost, high capacity and large natural reserve, and is considered to be an excellent pseudocapacitance material. Notably, pseudocapacitive materials generally cannot be used directly as flexible solid-state supercapacitor electrodes, which need to be composited with flexible conductive substrates, such as: carbon cloth, graphene and a metal substrate. Carbon cloth flexible substrates have the characteristics of good mechanical strength, high electrical conductivity, light weight and low cost, and have been widely used for flexible energy storage devices. Therefore, mixing Ni (OH)₂The method is an effective way for preparing the high-performance flexible electrode by combining the carbon cloth substrate. For example, Liu et al prepared β -Ni (OH) (2) nanoflake coated Carbon cloth by hydrothermal method using nickel nitrate, urea and ammonium fluoride as reaction system (The hydrothermal synthesis of beta-Ni (OH) (2) nanoflakes and The electronic properties. New Carbon Materials,2017,32(2), 116-).

However, the direct deposition of metal hydroxides on carbon cloth by traditional hydrothermal methods results in irregular morphologies with large geometries, which results in low utilization of the active material and thus low specific capacity. In addition, the porous nano heterostructure material shows good electrochemical performance due to its large specific surface area and improved electrode-electrolyte interface contact. Many efforts have been made to develop an effective preparation method of porous functional materials, and although some progress has been made, the design of mesoporous materials having an open structure is still a challenge.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a nickel hydroxide nano array/carbon cloth electrode material and a preparation method thereof.

The invention adopts the following specific technical scheme:

in a first aspect, the invention provides a preparation method of a nickel hydroxide nano array/carbon cloth electrode material, which comprises the following specific steps:

s1: putting the cleaned and dried carbon cloth into a first solution consisting of concentrated nitric acid and concentrated sulfuric acid, then carrying out activation treatment, and cleaning to obtain activated carbon cloth;

s2: immersing the activated carbon cloth in the second solution to obtain a mixed system; the second solution is obtained by dissolving nickel nitrate hexahydrate in absolute ethyl alcohol; and carrying out supercritical drying on the mixed system by using absolute ethyl alcohol to obtain the nickel hydroxide nano array/carbon cloth electrode material.

Preferably, the step S1 is as follows:

and cleaning the carbon cloth with ethanol, acetone and water, drying, putting into the first solution, then putting under a 3V potential together for activation treatment, and cleaning the activated carbon cloth with water to remove impurities to obtain the activated carbon cloth.

Further, the volume ratio of the concentrated nitric acid to the concentrated sulfuric acid in the first solution is 1: 1.

preferably, the volume ratio of the concentrated nitric acid to the concentrated sulfuric acid in the first solution is 1: 1.

preferably, the concentration of the nickel nitrate hexahydrate in the second solution is 0.01-0.5M.

Preferably, the supercritical drying process of the mixed system is carried out in a supercritical reaction kettle, and specifically comprises the following steps:

heating the supercritical reaction kettle to 265 ℃ at the heating rate of 5 ℃/min, wherein the pressure reaches 7MPa, so that the absolute ethyl alcohol in the supercritical reaction kettle reaches the supercritical point and changes from a liquid state to a gaseous state; after the reaction is carried out for 1h, discharging the ethanol gas in the supercritical reaction kettle, introducing nitrogen, and then cooling to room temperature to finish the supercritical drying process.

Further, the mixed system is placed in a glass culture dish, and the glass culture dish is placed in a supercritical reaction kettle filled with absolute ethyl alcohol for supercritical drying.

Furthermore, the absolute ethyl alcohol in the supercritical reaction kettle accounts for three-quarters of the volume of the supercritical reaction kettle.

Preferably, the mixed system is placed in a glass culture dish, and the glass culture dish is placed in a supercritical reaction kettle filled with absolute ethyl alcohol for supercritical drying.

Further, the liquid level of the absolute ethyl alcohol is lower than the top of the glass culture dish, so that the absolute ethyl alcohol is prevented from submerging the mixing system.

Preferably, the absolute ethyl alcohol in the supercritical reactor accounts for three-quarters of the volume of the supercritical reactor.

In a second aspect, the invention provides a nickel hydroxide nanoarray/carbon cloth electrode material obtained by the preparation method of any one of the first aspect, wherein the fiber structure of the carbon cloth is completely retained, and the microstructure stability is shown; the nickel hydroxide nanosheets uniformly grow on the carbon cloth and completely cover the carbon cloth, so that a three-dimensional porous network-shaped layered structure is formed.

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

compared with the conventional solvent, the invention utilizes the unique characteristics that the supercritical fluid (absolute ethyl alcohol in supercritical drying) has gas-like diffusivity, near-zero surface tension and excellent dissolving capacity, and uniformly covers the reactant on the surface of the complex porous material. In addition, the excellent wettability of the supercritical fluid ensures good contact between the reactants and the substrate. Therefore, the nickel hydroxide nano-array/carbon cloth electrode material prepared by supercritical drying treatment has the appearance of uniform distribution and layered porous structure, exposes more active sites and improves the utilization rate of active substances. A large number of open pore channels generated by interweaving adjacent nano sheets promote the transmission of electrolyte ions, and the method can be applied to super capacitors.

Drawings

In fig. 1, (a) and (b) are scanning electron microscope pictures of example 1, and (c) and (d) are scanning electron microscope pictures of the nickel hydroxide nano-array/carbon cloth electrode material prepared in example 2.

Detailed Description

The invention will be further elucidated and described with reference to the drawings and the detailed description. The technical features of the embodiments of the present invention can be combined correspondingly without mutual conflict.

Example 1

1) Washing commercial (directly purchased) carbon cloth with ethanol, acetone and deionized water for 15min, and drying in a drying oven.

2) And (3) putting the cleaned and dried carbon cloth into a container containing sulfuric acid and nitric acid (the volume ratio is 1: 1) then placed in an electrochemical workstation and subjected to an activation treatment at a potential of 3V for 10 minutes.

3) And (3) placing the activated carbon cloth in deionized water for 12h to remove impurities, and cleaning to obtain the activated carbon cloth.

4) 0.1g of Ni (NO)₃)₂·6H₂O (nickel nitrate hexahydrate) is dissolved in 10ml of absolute ethyl alcohol to form a clear second solution, the obtained second solution and an activated carbon cloth are placed into a glass culture dish together, and the activated carbon cloth is immersed in the second solution.

5) The petri dish was placed in a 500ml supercritical reaction kettle (a substrate was padded under the glass petri dish to ensure that the level of ethanol was below the petri dish) with 340ml absolute ethanol. Then the reaction kettle is heated to 265 ℃ at the heating rate of 5 ℃/min, the pressure in the reaction kettle reaches 7MPa, and at the moment, the absolute ethyl alcohol reaches the supercritical state (240 ℃, 6.3MPa) and changes from the liquid state to the gas state. After reacting for 1h under the state, discharging ethanol in the reaction kettle, introducing nitrogen, and then cooling the reaction kettle at room temperature to obtain the nickel hydroxide nano array/carbon cloth electrode material.

Scanning electron micrographs of the nickel hydroxide nano-array/carbon cloth electrode material prepared in this example are shown in fig. 1(a) and (b), and it can be seen from the images that the carbon cloth interwoven fiber structure is completely retained after supercritical deposition, exhibiting high microstructure stability, ni (oh)₂The nano-sheets uniformly grow on the carbon cloth fiber and realize complete coverageOpen pores and channels can be clearly observed between a large range of adjacent nanosheets, which can increase the contact area of the active material with the electrolyte. The nickel hydroxide nano array/carbon cloth electrode material prepared by the embodiment is subjected to constant current charge and discharge test at 2mA cm^-2The specific capacity calculated under the current density is 222mC cm^-2When the current density is 20mA cm^-2The capacity retention rate was 67.6%.

Example 2

1) Washing commercial carbon cloth with ethanol, acetone and deionized water for 15min, and drying in a drying oven.

2) And (3) putting the cleaned and dried carbon cloth into a container containing sulfuric acid and nitric acid (the volume ratio is 1: 1) then placed in an electrochemical workstation and subjected to an activation treatment at a potential of 3V for 10 minutes.

3) And (3) placing the activated carbon cloth in deionized water for 12h to remove impurities, and cleaning to obtain the activated carbon cloth.

4) 0.2g of Ni (NO)₃)₂·6H₂O (nickel nitrate hexahydrate) is dissolved in 10ml of absolute ethyl alcohol to form a clear second solution, the obtained second solution and an activated carbon cloth are placed into a glass culture dish together, and the activated carbon cloth is immersed in the second solution.

5) The petri dish was placed in a 500ml supercritical reaction kettle (a substrate was padded under the glass petri dish to ensure that the level of ethanol was below the petri dish) with 340ml absolute ethanol. Then the reaction kettle is heated to 265 ℃ at the heating rate of 5 ℃/min, the pressure in the reaction kettle reaches 7MPa, and at the moment, the absolute ethyl alcohol reaches the supercritical state (240 ℃, 6.3MPa) and changes from the liquid state to the gas state. After reacting for 1h under the state, discharging ethanol in the reaction kettle, introducing nitrogen, and then cooling the reaction kettle at room temperature to obtain the nickel hydroxide nano array/carbon cloth electrode material.

Scanning electron micrographs of the nickel hydroxide nano-array/carbon cloth electrode material prepared in the embodiment are shown in fig. 1(c) and (d), and it can be seen from the images that the material prepared in the embodiment has the same structure as the material obtained in example 1, but the size of the nano-sheet is slightly reduced. The nickel hydroxide nano array/carbon cloth electrode material prepared by the embodiment is subjected to constant current charge and discharge test at 2mA cm^-2The specific capacity calculated under the current density is 446mC cm^-2When the current density is 20mA cm^-2The capacity retention rate was 73.5%.

Example 3

1) Washing commercial carbon cloth with ethanol, acetone and deionized water for 15min, and drying in a drying oven.

2) And (3) putting the cleaned and dried carbon cloth into a container containing sulfuric acid and nitric acid (the volume ratio is 1: 1) then placed in an electrochemical workstation and subjected to an activation treatment at a potential of 3V for 10 minutes.

3) And (3) placing the activated carbon cloth in deionized water for 12h to remove impurities, and cleaning to obtain the activated carbon cloth.

4) 0.3g of Ni (NO)₃)₂·6H₂O (nickel nitrate hexahydrate) is dissolved in 10ml of absolute ethyl alcohol to form a clear second solution, the obtained second solution and an activated carbon cloth are placed into a glass culture dish together, and the activated carbon cloth is immersed in the second solution.

5) The petri dish was placed in a 500ml supercritical reaction kettle (a substrate was padded under the glass petri dish to ensure that the level of ethanol was below the petri dish) with 340ml absolute ethanol. Then the reaction kettle is heated to 265 ℃ at the heating rate of 5 ℃/min, the pressure in the reaction kettle reaches 7MPa, and at the moment, the absolute ethyl alcohol reaches the supercritical state (240 ℃, 6.3MPa) and changes from the liquid state to the gas state. After reacting for 1h under the state, discharging ethanol in the reaction kettle, introducing nitrogen, and then cooling the reaction kettle at room temperature to obtain the nickel hydroxide nano array/carbon cloth electrode material.

The nickel hydroxide nano array/carbon cloth electrode material prepared by the embodiment is subjected to constant current charge and discharge test at 2mA cm^-2The specific capacity calculated under the current density is 918mC cm^-2When the current density is 20mA cm^-2The capacity retention rate was 68.4%.

Example 4

1) Washing commercial carbon cloth with ethanol, acetone and deionized water for 15min, and drying in a drying oven.

2) And (3) putting the cleaned and dried carbon cloth into a container containing sulfuric acid and nitric acid (the volume ratio is 1: 1) then placed in an electrochemical workstation and subjected to an activation treatment at a potential of 3V for 10 minutes.

3) And (3) placing the activated carbon cloth in deionized water for 12h to remove impurities, and cleaning to obtain the activated carbon cloth.

4) 0.4g of Ni (NO)₃)₂·6H₂O (nickel nitrate hexahydrate) is dissolved in 10ml of absolute ethyl alcohol to form a clear second solution, the obtained second solution and an activated carbon cloth are placed into a glass culture dish together, and the activated carbon cloth is immersed in the second solution.

5) The petri dish was placed in a 500ml supercritical reaction kettle (a substrate was padded under the glass petri dish to ensure that the level of ethanol was below the petri dish) with 340ml absolute ethanol. Then the reaction kettle is heated to 265 ℃ at the heating rate of 5 ℃/min, the pressure in the reaction kettle reaches 7MPa, and at the moment, the absolute ethyl alcohol reaches the supercritical state (240 ℃, 6.3MPa) and changes from the liquid state to the gas state. After reacting for 1h under the state, discharging ethanol in the reaction kettle, introducing nitrogen, and then cooling the reaction kettle at room temperature to obtain the nickel hydroxide nano array/carbon cloth electrode material.

The nickel hydroxide nano array/carbon cloth electrode material prepared by the embodiment is subjected to constant current charge and discharge test at 2mA cm^-2The specific capacity calculated under the current density is 898mC cm^-2When the current density is 20mA cm^-2The capacity retention rate was 50.6%.

The research results of the embodiments 1 to 4 show that the performance of the finally prepared material can be regulated and controlled by changing the concentration of the nickel nitrate hexahydrate in the second solution.

The above-described embodiments are merely preferred embodiments of the present invention, which should not be construed as limiting the invention. Various changes and modifications may be made by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present invention. Therefore, the technical scheme obtained by adopting the mode of equivalent replacement or equivalent transformation is within the protection scope of the invention.