CN113809304B - Preparation method and application of a plasma-based tin dioxide/carbon nanotube composite material - Google Patents

Abstract

The invention discloses a preparation method and application of a tin dioxide/carbon nano tube composite material based on plasma, wherein micron-sized high-purity tin metal powder, a carbon nano tube and deionized water are uniformly mixed according to a certain proportion to be in a semi-fluid state and are pressed into a cylinder shape to be used as a cathode; the method comprises the following steps of adopting a refractory conductive material as a positive electrode, keeping a certain distance from the positive electrode, switching on a power supply to generate direct current arc plasma, realizing uniform loading of tin dioxide nanoparticles on the surface of a carbon nanotube while dispersing the carbon nanotube to obtain a tin dioxide/carbon nanotube composite material, and drying the tin dioxide/carbon nanotube composite material to be used as a negative electrode of a lithium ion battery; compared with a chemical method, the preparation method has the advantages of simplicity, rapidness, green and the like, and the carbon nano tube conductive network structure not only provides enough space for the volume expansion of tin dioxide, but also is beneficial to electron transfer; the method is expected to realize industrialization, and provides a new idea for preparation of other nano composite materials.

Description

A kind of preparation method of tin dioxide/carbon nanotube composite material based on plasma law and its application

technical field

The invention belongs to the technical field of nanomaterial preparation, and in particular relates to a preparation method and application of a plasma-based tin dioxide/carbon nanotube composite material.

Background technique

The information disclosed in this background section is only intended to increase some understanding of the general background of the disclosure, and is not necessarily to be taken as an acknowledgment or any form of suggestion that the information constitutes prior art that is already known to those skilled in the art.

As an ideal energy storage device, lithium-ion batteries are widely used in electric vehicles, power grids, and electronic equipment energy storage due to their advantages such as high energy density, long cycle life, and low cost. At present, as a commercial lithium-ion battery anode material, graphite cannot meet the increasing demand for energy storage due to its shortcomings such as low theoretical specific capacitance and limited cycle rate. Therefore, it is urgent to seek new high-performance alternative anode materials.

Tin dioxide is widely used in lithium battery electrode materials because of its high theoretical specific capacity (781mAh/g). However, in the application process, there are problems such as large irreversible capacity for the first time, large volume effect (volume expansion of 250% to 300%) when intercalating lithium, and easy agglomeration during cycling. Therefore, it is often combined with other materials to improve the secondary The dispersibility of tin oxide particles can inhibit particle agglomeration and improve the cycle stability of electrode materials. Carbon nanotubes have the advantages of large specific surface area, good electrical conductivity, and strong chemical stability, and have become widely used carrier materials.

However, the preparation of carbon nanotubes/tin dioxide composite materials in the prior art mostly adopts complex chemical methods. There is a technology that mixes purified and modified carbon nanotubes with tin tetrachloride solution and ultrasonically treats the resulting solution Concentrated ammonia water was added dropwise and the pH was adjusted to 9. After stirring for 3 hours, the solution was suction filtered, washed and dried, and the obtained filter residue was calcined at 600° C. for 1 hour to obtain a carbon nanotube/tin dioxide composite electrode. For the chemical preparation method, on the one hand, the use of chemical reagents causes impurities to be easily introduced during the preparation process, which adversely affects performance and causes environmental pollution; on the other hand, the complexity of the preparation process is not conducive to large-scale production. Therefore, the development of a A simple and clean preparation method of tin dioxide/carbon nanotubes is of great significance.

Contents of the invention

The purpose of the present invention is to provide a kind of preparation method and application thereof based on plasma tin dioxide/carbon nanotube composite material, which solves the complex process of preparing tin dioxide/carbon nanotube composite material by chemical method proposed in the background technology Sexuality and the impurity caused by the use of many chemical reagents are difficult to remove and other issues.

The preparation method of the plasma-based tin dioxide/carbon nanotube composite material provided by the present invention, on the one hand, can increase the contact area between tin dioxide and carbon nanotubes on the basis of ensuring the uniformity of carbon nanotube dispersion, and promote the two On the other hand, by adjusting the mass ratio of carbon nanotubes and tin sources, tin dioxide/carbon nanotube composites coated with different tin dioxide contents can be obtained, so as to meet the electrochemical and other performance requirements of lithium battery electrode materials .

In order to solve the above problems, the technical solution adopted in the present invention is:

A method for preparing a plasma-based tin dioxide/carbon nanotube composite material, comprising the steps of:

S1: Evenly mix tin metal powder, carbon nanotubes and deionized water to a semi-fluid state;

S2: pressing the semi-fluid mixture prepared in S1 into a cylindrical solid;

S3: using the cylindrical solid material prepared in step S2 as a negative electrode, using a refractory conductive material as a positive electrode, and respectively connecting the negative electrode and the positive electrode to a power supply;

S4: When the power is turned on, a DC arc plasma is generated between the negative electrode and the positive electrode to form a carbon nanotube dispersed fog. Tin oxide/carbon nanotube composites;

S5: Collect the tin dioxide/carbon nanotube composite material prepared in step S4, sonicate, filter, and dry.

Preferably, the tin metal powder is micron-sized high-purity tin metal powder; the mass ratio of the micron-sized high-purity tin metal powder, carbon nanotubes, and deionized water is 8:1:5.

Preferably, the refractory conductive material is one of iron, copper, aluminum, tungsten and graphite.

Preferably, the refractory conductive material is tungsten or graphite.

Preferably, in step S3, the distance between the negative electrode and the positive electrode is 2-5mm, and the power supply parameters are: voltage 8000-10000V, power 50W, frequency 0.1HZ-10HZ.

Preferably, in step S5, the ultrasonic time of the tin dioxide/carbon nanotube composite material is 0.5 h, the drying temperature is 60-150° C., and the drying time is 1-2 h.

An application of a plasma-based tin dioxide/carbon nanotube composite material, and an application of a plasma-based tin dioxide/carbon nanotube composite material in lithium battery anode materials.

The beneficial effects of the present invention are:

1. A kind of preparation method of the tin dioxide/carbon nanotube composite material based on plasma of the present invention, compared with chemical method, does not have the use of any chemical reagent, has the advantage such as preparation is simple, fast, green, in carbon nanotube While dispersing, the uniform loading of tin dioxide nanoparticles on the surface of carbon nanotubes is realized. The conductive network structure of carbon nanotubes can not only provide enough space for the volume expansion of tin dioxide, but also help to transfer electrons between the electrode and tin dioxide during the lithium ion intercalation/deintercalation process. While this method is expected to be industrialized, it also provides a new idea for the preparation of other nanocomposites.

2. The cylindrical solid material of the present invention is used as the negative pole, and when the power is turned on, a DC arc plasma is generated between the negative pole and the positive pole to form a carbon nanotube dispersed mist, while the tin metal powder is gasified and oxidized; carbon nanotubes and tin metal powder are mixed Pressed into a cylindrical solid material and used as the negative electrode at the same time, the carbon nanotube dispersion and the gasification and oxidation of the tin metal powder synergize, that is, the formation of the carbon nanotube dispersed mist hinders the collision and aggregation between the tin metal vapors, and effectively inhibits the collision between the tin vapors. The particle agglomeration caused by adopting the preparation method of the present invention is all nano-scale; simultaneously, it is beneficial to the better combination of tin vapor and carbon nanotube dispersion mist, and improves the dispersion of tin dioxide on the surface of carbon nanotubes. The combination of tin dioxide and carbon nanotubes is attributed to the condensation and oxidation of tin vapor on the surface of carbon nanotubes. After ultrasonication, tin dioxide still exists stably on the surface of carbon nanotubes, showing good bonding strength.

Description of drawings

Fig. 1 is the morphology characterization of the tin dioxide/carbon nanotube composite material prepared by the present invention;

Among them: (a) is the scanning electron microscope image (SEM) of SnO ₂ /CNTs; (b), (c) is the transmission electron microscope image (TEM) of SnO ₂ /CNTs under different magnifications; (d) is the SnO ₂ /CNTs High-resolution transmission electron microscope image (HRTEM);

Fig. 2 is the X-ray diffraction (XRD) pattern of SnO ₂ /CNTs prepared by the present invention and commercially available tin dioxide;

Fig. 3 is the specific surface area and pore size distribution of the SnO ₂ /CNTs composite material prepared by the present invention;

Where: (e) is the nitrogen adsorption/desorption isotherm of the SnO ₂ /CNTs composite; (f) is the pore size distribution of the SnO ₂ /CNTs composite obtained by the Barrett-Joyner-Halenda method;

Figure 4 shows the cycle stability at a current density of 100mAg ^-1 of SnO ₂ /CNTs prepared by the patent of the present invention and commercially available SnO ₂ as lithium-ion battery negative electrode materials.

Figure 5 is the electrochemical impedance spectrum of SnO ₂ /CNTs prepared by the patent of the present invention and commercially available SnO ₂ as lithium-ion battery negative electrode materials in the frequency range of 0.01Hz-100KHz;

Detailed ways

In order to clearly illustrate the technical characteristics of this solution, the following will describe this solution through specific implementation modes and in conjunction with the accompanying drawings.

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

It should be noted that the terminology used herein is only for describing specific embodiments, and is not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations and/or combinations thereof.

Example

1. Preparation of tin dioxide/carbon nanotube composites

A method for preparing a plasma-based tin dioxide/carbon nanotube composite material, comprising the steps of:

S1: Mix micron-sized high-purity tin metal powder, carbon nanotubes and deionized water evenly to a semi-fluid state according to the mass ratio of 8:1:5;

S2: pressing the semi-fluid mixture prepared in S1 into a cylindrical solid;

S3: The cylindrical solid material prepared in step S2 is used as the negative electrode, and the metal tungsten wire conductive material is used as the positive electrode, and the negative electrode, the positive electrode and the power supply are respectively connected correspondingly; the distance between the negative electrode and the positive electrode is 2-5mm; The power parameters are: voltage 8000V, power 50W, frequency 5HZ;

S4: When the power is turned on, a DC arc plasma is generated between the negative electrode and the positive electrode to form a carbon nanotube dispersed fog. Tin oxide/carbon nanotube composites;

S5: Collect the tin dioxide/carbon nanotube composite material prepared in step S4, sonicate for 0.5 h, and dry at 100° C. for 2 h.

2. Application of a plasma-based tin dioxide/carbon nanotube composite material

An application of a plasma-based tin dioxide/carbon nanotube composite material, the plasma-based tin dioxide/carbon nanotube composite material of the present invention is applied to lithium battery negative electrode materials.

Electrochemical performance test

The electrochemical performance was carried out under the following conditions: the tin dioxide/carbon nanotube composite material prepared above was mixed with conductive carbon black and polyvinylidene fluoride as the negative electrode active material, and the tin dioxide/carbon nanotube composite material was mixed with conductive carbon The weight ratio of black and polyvinylidene fluoride is 8:1:1, and N-methylpyrrolidone is used as a solvent. After being fully mixed, it is evenly coated on a copper foil, and dried at 80°C for punching to obtain a working electrode. In the glove box, a 2032 button cell was assembled with a pure lithium sheet as the counter electrode, wherein the separator was a polypropylene/polyethylene microporous membrane, and the electrolyte was 1.15M LiPF ₆ /ethylene carbonate-dimethyl carbonate. The charge and discharge test is carried out on the electrical test system, and the voltage window is 0.01V-3V. The electrochemical impedance spectroscopy test was carried out using an electrochemical workstation (CHI660D) in the frequency range of 0.01Hz-100KHz.

Fig. 1 is the morphology characterization figure of the tin dioxide/carbon nanotube composite material (SnO ₂ /CNTs ₎ prepared by the present invention, can see obvious carbon nanotube tubular structure from Fig. 1, and SnO Uniform load on There is no obvious agglomeration phenomenon on the carbon nanotubes, thus, the plasma-based tin dioxide/carbon nanotube composite material of the present invention has good dispersibility.

Fig. 2 is the X-ray diffraction pattern of SnO ₂ /CNTs prepared by the present invention and commercially available tin dioxide (SnO ₂ ), by comparing with the standard value card (JCPDS 41-1445), it can be seen that the main diffraction peaks are similar to those of SnO The tetragonal rutile phase of ₂ fits well, indicating that Sn metal powders formed SnO ₂ nanoparticles under the action of DC arc plasma.

Fig. 3 is the specific surface area and pore size distribution of the SnO ₂ /CNTs composite material prepared by the present invention, the result shows that the specific surface area of the SnO ₂ /CNTs composite material is 181.92m ² g ^-1 , analyzed by the Barrett-Joyner-Halenda (BJH) method The pore size distribution, the pore volume is 0.89mL g ^-1 , and the average pore diameter is 16.76nm. The large specific surface area and pore volume are beneficial to reduce the strain caused by the electrochemical cycle process, relieve the volume expansion of tin dioxide, and improve cycle stability.

Fig. 4 is the cycle stability under the 100mAg ^-1 current density of the SnO ₂ /CNTs prepared by the present invention and commercially available SnO ₂ as lithium-ion battery anode material, can find out from the figure although commercially available SnO ₂ shows higher Initial discharge capacity, but after 60 cycles the capacity drops rapidly to less than 200mAh g ^-1 , and the cycle stability is poor, while the _SnO2 /CNTs prepared in this application show high cycle stability, 200 cycles at 100mA g ^-1 After that, it still has a capacity of 472mAh g ^-1 .

Fig. 5 is the electrochemical impedance spectroscopy (EIS) of _SnO2 /CNTs prepared by the present invention and commercially available _SnO2 in the frequency range of 0.01Hz-100KHz as lithium-ion battery negative electrode material, can find out among the figure the electric charge of _SnO2 /CNTs The transfer resistance is 119.8 Ω, which is lower than 198.7 Ω of commercially available _SnO2 , indicating that the introduction of carbon nanotubes accelerates the electron transport during the electrochemical reaction and has higher charge transfer efficiency. At the same time, at low frequencies, the slope of the straight line represents the ionic conductivity of the material, and the impedance slope of SnO ₂ /CNTs is larger than that of commercially available SnO ₂ , indicating that SnO ₂ /CNTs has superior Li ⁺ diffusion speed and thus better storage capacity. lithium characteristics and exhibit better electrochemical performance.

To sum up, a method for preparing a plasma-based tin dioxide/carbon nanotube composite material of the present invention, compared with chemical methods, does not use any chemical reagents, and has the advantages of simple, fast, and green preparation. While the tubes are dispersed, the uniform loading of tin dioxide nanoparticles on the surface of carbon nanotubes is realized. And the conductive network structure of carbon nanotubes can not only provide enough space for the volume expansion of tin dioxide, but also help to transfer electrons between electrodes and tin dioxide during the lithium ion intercalation/deintercalation process; the present invention prepares A high-performance tin dioxide/carbon nanotube composite material can be used as a good negative electrode material for lithium batteries.

The above-mentioned embodiment is a preferred implementation mode of the present disclosure, but the implementation mode of the present disclosure is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, All simplifications should be equivalent replacement methods, and all are included in the protection scope of the present disclosure.

Claims (7)

1. a preparation method based on plasma-based tin dioxide/carbon nanotube composite material, is characterized in that, comprises the steps: S1: Evenly mix tin metal powder, carbon nanotubes, and deionized water to a semi-fluid state; the tin metal powder is micron-sized high-purity tin metal powder; the micron-sized high-purity tin metal powder, carbon nanotubes, and deionized water are The ratio is 8:1:5; S2: pressing the semi-fluid mixture prepared in S1 into a cylindrical solid; S3: using the cylindrical solid material prepared in step S2 as a negative electrode, using a refractory conductive material as a positive electrode, and respectively connecting the negative electrode and the positive electrode to a power supply; S4: When the power is turned on, a DC arc plasma is generated between the negative electrode and the positive electrode to form a carbon nanotube dispersed fog. Tin dioxide/carbon nanotube composites; S5: Collect the tin dioxide/carbon nanotube composite material prepared in step S4, sonicate, filter, and dry. 2. the preparation method of tin dioxide/carbon nanotube composite material as claimed in claim 1, is characterized in that, described refractory conductive material is a kind of of iron, copper, aluminum, tungsten, graphite. 3. the preparation method of tin dioxide/carbon nanotube composite material as claimed in claim 2, is characterized in that, described refractory conductive material is tungsten or graphite. 4. the preparation method of tin dioxide/carbon nanotube composite material as claimed in claim 1, is characterized in that, in step S3, the distance between negative pole and positive pole two electrodes is 2～5 mm, and described power supply parameter It is: voltage 8000~10000 V, power 50 W, frequency 0.1 HZ-10 HZ. 5. The preparation method of the tin dioxide/carbon nanotube composite material as claimed in claim 1, characterized in that, in step S5, the ultrasonic time of the tin dioxide/carbon nanotube composite material is 0.5 h. 6. The preparation method of tin dioxide/carbon nanotube composite material as claimed in claim 1, is characterized in that, in step S5, the drying temperature of described tin dioxide/carbon nanotube composite material is 60～150 ℃, The drying time is 1~2 h. 7. The application of a plasma-based tin dioxide/carbon nanotube composite material is characterized in that the tin dioxide/carbon nanotube composite material is prepared by the preparation method as described in any one of claims 1-6, based on Application of plasmonic tin dioxide/carbon nanotube composites in lithium battery anode materials.

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