CN100420626C - Preparation method of pure carbon nanotube film - Google Patents

Abstract

The invention discloses a preparing method of pure-carbon nanometer pipe film, which comprises the following steps: adopting electric spinning method or solution spinning method; spraying composite solution of carbon nanometer pipe and dispersant on the receiving board; heating to volatilize dispersant; or removing dispersant through distilled water.

Description

Preparation method of pure carbon nanotube film

Technical field

The invention relates to the preparation of a nanometer material, in particular to a preparation method of a pure carbon nanotube film.

Background technique

Carbon nanotubes were discovered by Japanese electron microscope expert Iijima in 1991. Carbon nanotubes are divided into multi-walled carbon nanotubes (also known as bucky tubes) and single-walled carbon nanotubes. Due to the unique structure of carbon nanotubes, the carbon nanotube films formed by them have broad application prospects in catalyst supports, semiconductor materials, field emission, optoelectronic devices, and energy storage. For example, when carbon nanotube films are used as electrode materials, they have the advantages of high crystallinity, good electrical conductivity, large specific surface area, concentrated pore size distribution within a certain range, and controllable pore size.

The preparation method of existing carbon nanotube thin film has: one, adopt chemical vapor deposition method, catalytic cracking method etc., in the preparation process carbon nanotube promptly grows on the substrate with the form of thin film, and its shortcoming is: preparation process needs catalyst, Due to the high temperature, the preparation process is complicated, and the film grows on the substrate. The film cannot be peeled off and used alone, which limits its application range. 2. Using ordinary coating technology to coat carbon nanomaterials on the substrate through adhesives, the disadvantages are: the preparation process is cumbersome, the combination is not strong, and the film is easy to crack in the later drying process, and due to the addition of adhesive The binding agent makes the components of the pure carbon nanotube film impure, and the performance of the pure carbon nanotube film deteriorates.

Contents of the invention

The purpose of the present invention is to provide a preparation method of pure carbon nanotube film, the preparation process is simple, the production cost is low, the pure carbon nanotube film material has good electrical conductivity, low internal resistance, and high utilization rate of carbon nanotubes .

The technical scheme adopted by the present invention to realize its inventive purpose is: a kind of preparation method of pure carbon nanotube thin film, and its way is: adopt electrospinning method or solution spinning method, the mixed solution of carbon nanotube and dispersing agent is sprayed to the receiving plate; then evaporate the dispersant by heating, or wash with distilled water to remove the dispersant.

The electrospinning method is a spinning technology under the action of an electric field. Its working principle is: add the mixture of carbon nanotubes and dispersant into the syringe, and then connect the power supply through the metal electrode placed in the liquid. The liquid is affected by surface tension and electric field force; as the voltage increases and the electric field strength increases, the same-sex charges in the solution are forced to gather on the surface of the droplet, and the solution at the end gradually changes from a hemispherical shape to a cone shape. When the critical electric field The force exceeds the surface tension, and a charged liquid stream is ejected from the nozzle end onto the receiving plate of the receiving device, forming a thin film.

The solution spinning method is to use high pressure to spray liquid on the receiving plate to form a thin film.

Compared with the prior art, the beneficial effect of the present invention is: the mixture of carbon nanotubes and dispersant is sprayed onto the receiving plate by electrospinning or solution spraying, and the carbon nanotubes are sprayed under high voltage or high pressure. Under the action of carbon nanotubes, carbon nanotubes produce nano-effects and form a thin film closely combined with each other. The carbon nanotubes are closely combined with each other, the film-forming performance is good, the film is not easy to crack, and can be peeled off from the receiving plate for separate use, and has a wide range of applications. The prepared carbon nanotube film does not need to be mixed with materials such as binders, the composition of the carbon nanotube film is pure, the utilization rate of carbon nanomaterials is high, the specific surface area is large, and the electrochemical performance is good.

The carbon nanotube thin film prepared by the method of the invention is used for making capacitor electrodes, and has low internal resistance, good conductivity and high electrochemical capacity.

The above-mentioned dispersant is N, N-dimethylformamide, sodium dodecylbenzenesulfonate, lithium dodecyl sulfate, 2-methoxyethanol, propylene carbonate, triethanolamine, sodium triphosphate, poly One or more mixed liquids of acrylic acid; the mass ratio of carbon nanotubes and dispersants is 1:1-1000.

The above-mentioned mixed solution of carbon nanotubes and dispersant is formed through the step of ultrasonic dispersion to form a uniformly dispersed mixed solution. This can make the mixing and dispersion more uniform, and in the prepared film, the distribution of carbon nanotubes is more uniform, and the performance of the film is better.

When the aforementioned electrospinning method is used for spraying, the receiving plate used is a conductive receiving plate made of metal or graphite.

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is a 200 times optical microscope image of a pure carbon nanotube film prepared by the method of Example 1 of the present invention.

Fig. 2 is a 10,000 times scanning electron micrograph (SEM) image of a pure carbon nanotube film prepared by the method of Example 1 of the present invention.

FIG. 3 is a 200-fold optical microscope image of a carbon nanotube film prepared by a common coating method.

Detailed ways

Embodiment one

a. Fully mix the multi-walled carbon nanotube material and N,N-dimethylformamide solution at a mass ratio of 1:500 at room temperature, and then perform ultrasonic dispersion to make the solution uniformly dispersed.

b. Add the mixed solution into the electrospinning syringe, place an aluminum foil as a receiving plate at a distance of 15 cm from the spinneret, adjust the voltage of the syringe to 30KV, the injection speed of the mixed solution to 0.1mL/s, and the spinning time to 1h.

c. drying the prepared film in a vacuum environment at a temperature of 200° C. to obtain a pure carbon nanotube film.

Figures 1 and 2 show that the microscopic image of the carbon nanotube film prepared in this example is clear, indicating that the film surface is smooth without unevenness, and there are no cracks caused by drying and other reasons. Figure 3 shows that the optical microscopic image of the carbon nanotube film prepared by the ordinary coating method is blurred in some areas, and some cracks appear, indicating that the film obtained by the ordinary coating technology is not only uneven, but also uneven Not flat and cracked after drying.

The pure carbon nanotube film of this example can be directly used as a material for making capacitor electrodes, or the film can be peeled off from the aluminum foil for other purposes.

Embodiment two

The method of this example is basically the same as that of Example 1, except that the carbon nanotubes are single-walled carbon nanotubes, the dispersant is triethanolamine, and the mass ratio of single-walled carbon nanotubes to triethanolamine is 1: 1000. The mixture is directly mixed and stirred without ultrasonic treatment. The prepared film was soaked in distilled water to remove the triethanolamine dispersant.

Embodiment three

The method of this example is basically the same as the preparation method of embodiment one, and the difference is only: the dispersant is sodium dodecylbenzenesulfonate, and the mass ratio of single-walled carbon nanotubes and sodium dodecylbenzenesulfonate is 1:1, the receiving plate is made of nickel material.

Embodiment Four

The method of this example is basically the same as that of Example 1, except that the dispersant is lithium dodecyl sulfate, and the mass ratio of multi-walled carbon nanotubes to lithium dodecyl sulfate is 1:50. The receiver plate is made of silver material.

Embodiment five

The method of this example is basically the same as that of Example 1, except that the dispersant is 2-methoxyethanol, and the mass ratio of multi-walled carbon nanotubes to 2-methoxyethanol is 1:100. The receiving plate is a graphite receiving plate.

Embodiment six

The method of this example is basically the same as that of Example 1, except that the dispersant is a mixed solution of sodium triphosphate, polyacrylic acid and N, N-dimethylformamide (volume ratio is 1: 1: 1), the mass ratio of multi-walled carbon nanotubes to the mixed solution is 1:500. The receiving plate is a stainless steel receiving plate.

Embodiment seven

The method of this example is to use the solution spinning method, after mixing the single-walled carbon nanotubes and propylene carbonate at a mass ratio of 1:200, ultrasonically disperse them into a uniform mixed solution, and then inject them into the syringe of the solution spinning method , inject the mixture onto the glass receiver plate via a syringe. Then remove the dispersant by washing with distilled water.

Embodiment Eight

The method of this example is basically the same as that of Example 7, except that the dispersant is sodium triphosphate, and the receiving plate is a copper plate.

The pure carbon nanotube film made in Example 1 is directly made into an electrochemical supercapacitor electrode and a capacitor thereof, which proves that its electrochemical performance is superior:

The aluminum foil with pure carbon nanotube film prepared in Example 1 was made into a disc-shaped electrode (2×10 ^-4 m ² ) using the existing capacitor electrode manufacturing technology, which was used as the positive and negative electrodes of the supercapacitor. Using the American Celgard2400 film as the separator layer, in an argon glove box, use 0.1mol/L LiClO ₄ (using ethyl carbonate and diethyl carbonate with a volume ratio of 1:1 as the solvent) to soak the separator After the layers and the positive and negative electrodes, the aluminum foil receiving plates of the positive and negative electrodes are facing away from each other, and the side with the carbon nanotube film is opposite, and the separator layer is embedded in the middle, that is, a button-type electrochemical supercapacitor is assembled.

Performance test: test its electrochemical behavior on a DC-5 battery tester in a charge-discharge mode with a constant current density of 3.5A/m ² and a charge-discharge range of 0-2.5V. The reversible capacity is based on its discharge curve, and is calculated according to the formula C=(I×t)/U (middle, C represents the electrochemical capacity of the material; I represents a constant current; t represents the discharge time; U represents the voltage range of the discharge) .

The test results show that: under the 0.2mA constant current charge-discharge mode, the single-electrode capacity of this capacitor is 32F/g in the organic electrolyte, which is 25% higher than the single-electrode capacity of the capacitor 24F/g made by the prior art. %, In addition, its cycle and electrical conductivity have been greatly improved.

The specific process conditions of the present invention can be determined according to the prior art and the film thickness required to be formed by spraying. Usually the injection time is 0.0003-10h, the injection flow rate is 0.0001-10mL/s, the distance between the spinneret and the receiving plate is 0.1-100cm, the voltage of the electrospray method is 0.1-1000KV, and the pressure of the solution method is 0.1-100MPa; The thickness of the prepared carbon nanotube film is 0.1-1000 μm.

The spinneret of the electrospinning method and the solution spinning method can be placed horizontally or vertically, and the receiving plate can be in the shape of a flat plate, a turntable or a cylinder. Apparently, the function of the receiving plate used in the solution spinning method of the present invention is to block and receive the sprayed mixed liquid, and to make the carbon nanotubes in the mixed liquid form a thin film thereon. Therefore, the receiver plate can be any flat plate that does not chemically react with the carbon nanotubes. And the effect of the receiving plate adopted in the electrospinning method of the present invention, in addition to the above-mentioned effect identical with the solution spinning method, also serves as another electrode of high voltage in the electrospinning device, generates attraction to the mixed liquid, absorbs and charges The mixed liquid is deposited on the surface of the receiving plate, so it is generally a conductive plate.

The dispersant of the present invention can select the corresponding single dispersant or mixed dispersant and the mixing ratio between the dispersants thereof according to the knowledge of the prior art according to the type, purpose and thickness of the carbon nanotube film made, so that the carbon nanotube Better even dispersion.

In the present invention, after the mixed liquid is sprayed onto the receiving plate with high voltage or high pressure, the dispersants on the receiving plate can be washed and removed with distilled water, and obviously can also be dissolved and washed with the corresponding solvents of these dispersants.

Claims (4)

1. the preparation method of a pure nano-carbon tube film, its way is: adopt electrical spinning method or solution spray method, the mixed solution of carbon nanotube and dispersion agent is injected on the dash receiver; Make the dispersion agent volatilization by heating then, or remove dispersion agent, get final product with distilled water wash.

2. the preparation method of pure nano-carbon tube film according to claim 1, it is characterized in that: described dispersion agent is N, the mixed solution of one or more in dinethylformamide, sodium dodecyl benzenylsulfonate, lithium dodecyl sulfate, 2-methyl cellosolve, propylene carbonate, trolamine, Tri sodium Phosphate, the polyacrylic acid; The mass ratio of carbon nanotube and dispersion agent is 1: 1～1000.

3. the preparation method of pure nano-carbon tube film according to claim 1 and 2, it is characterized in that: the mixed solution of described carbon nanotube and dispersion agent forms homodisperse mixed solution by the step of ultra-sonic dispersion.

4. the preparation method of pure nano-carbon tube film according to claim 1 is characterized in that: when described employing electrical spinning method sprayed, the dash receiver of employing was the conduction dash receiver that metal or graphite constitute.

Images