CN102412400A - Silver vanadium oxide / polymer three coaxial nanowire and preparation method and application thereof - Google Patents

Abstract

The invention relates to a silver vanadium oxide/polymer triaxial nanowire and a preparation method thereof, as well as the application of the material as a positive electrode active material of a lithium-ion battery, which has an obvious triaxial structure and a length of 10 to 30 microns. The diameter is 60-100 nanometers, the core is β-AgVO ₃ nanowires, the middle layer is the silver vanadium oxide layer produced by losing part of the silver ions on the surface of β-AgVO ₃ nanowires, the outermost layer is a polymer layer, the outermost The thickness of the layer is 6-10 nanometers, and the thickness of the middle layer is 6-10 nanometers. The beneficial effects of the present invention are: when the nanowire is used as the positive electrode active material of a lithium ion battery, it shows significantly improved specific capacity and cycle stability; The obtained material has high purity and good dispersion; in addition, compared with other methods for preparing triaxial nanowires, chemical in-situ polymerization uses water as the medium, and triaxial nanowires can be realized after a short period of stirring at room temperature and pressure. The synthesis of threads is beneficial to market promotion.

Description

Silver vanadium oxide/polymer triaxial nanowire and its preparation method and application

technical field

The invention belongs to the technical field of nanomaterials and electrochemistry, and in particular relates to a silver vanadium oxide/polymer triaxial nanowire and a preparation method thereof, and the application of the material as a positive active material of a lithium ion battery.

Background technique

As a green energy source, lithium-ion batteries have been used in portable electronic devices and electric vehicles. Research on high-capacity, miniaturized, high-power, and low-cost lithium-ion batteries based on new nano-heterostructures is the key to lithium-ion batteries in the current low-carbon economic era. One of the frontiers and hotspots of research. Ag ₂ V ₄ O ₁₁ has the advantages of high energy density, safe and reliable performance, etc., so it is used as a lithium-ion primary battery material for cardiac pacemakers. Compared with Ag ₂ V ₄ O ₁₁ , β-AgVO ₃ is considered to have better electrochemical performance due to its higher Ag:V ratio. However, there are few reports on the research on β-AgVO ₃ as the cathode material of lithium-ion secondary batteries, and silver vanadium oxide still has the disadvantages of low conductivity, fast capacity decay, and poor cycle reversibility.

In recent years, nanowires with complex structures (such as coaxial nanowires, triaxial nanowires, etc.) have attracted more and more attention in the fields of electrochemistry and energy due to their excellent properties. Conductive polymers have good air stability, high conductivity, environmental non-toxicity, reversible redox characteristics and other characteristics, and are widely used in the construction and electrochemical modification of coaxial nanowires. However, triaxial nanowires with conductive polymer shells have not been reported yet.

Contents of the invention

The technical problem to be solved by the present invention is to provide a silver vanadium oxide/polymer triaxial nanowire with a simple preparation process, meet the requirements of green chemistry, and have excellent electrochemical performance and a preparation method thereof.

Another object of the present invention is to provide the application of the silver vanadium oxide/polymer triaxial nanowire.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: silver vanadium oxide/polymer triaxial nanowire, which is characterized in that it has an obvious triaxial structure, the length is 10-30 microns, and the diameter is 60-100 Nano, wherein the core is β-AgVO ₃ nanowires, the middle layer is a silver vanadium oxide layer produced by losing part of the silver ions on the surface of β-AgVO ₃ nanowires, the outermost layer is a polymer layer, and the thickness of the outermost layer is 6~ 10 nanometers, the thickness of the middle layer is 6~10 nanometers.

According to the above scheme, the polymer is polyaniline, polypyrrole or polythiophene.

The preparation method of silver vanadium oxide/polymer triaxial nanowire is characterized in that comprising the following steps:

1) Mix the vanadium source aqueous solution and the silver source aqueous solution under stirring conditions to obtain a precursor solution;

2) Transfer the precursor solution obtained in step 1) to the reactor for reaction, naturally cool to room temperature, and centrifuge to obtain the precipitate;

3) Repeatedly washing the precipitate obtained in step 2) with deionized water, and drying to obtain β-AgVO ₃ nanowires;

4) Disperse β-AgVO ₃ nanowires in deionized water, add polymer monomers, wherein the mass ratio of β-AgVO ₃ nanowires to polymer monomers is 2:1, stir at room temperature for 10-14 hours, and then Add an aqueous oxidant solution in the same amount as the polymer monomer, continue to stir at room temperature for 10 to 14 hours, and centrifuge to obtain the precipitated product;

5) The precipitated product obtained in step 4) was repeatedly washed with deionized water and absolute ethanol, and dried to obtain silver vanadium oxide/polymer triaxial nanowires.

According to the above scheme, the vanadium source includes but not limited to ammonium metavanadate or vanadium pentoxide sol.

According to the above scheme, the silver source includes but not limited to silver nitrate, silver acetate or silver carbonate.

According to the above scheme, the polymer monomers include but not limited to aniline monomers, pyrrole monomers or thiophene monomers.

According to the above scheme, the reaction temperature in step 2) is 160°C~200°C, and the reaction time is 12~36 hours.

According to the above scheme, the oxidizing agent includes but not limited to ammonium persulfate, potassium dichromate or ferric chloride.

The application of the silver vanadium oxide/polymer triaxial nanowires as positive electrode active materials of lithium ion batteries.

The beneficial effects of the present invention are: based on β- _AgVO3 nanowires, silver vanadium oxide/polymer nanowires with obvious triaxial structure are prepared by combining chemical in-situ polymerization method and solid-liquid interface redox reaction method, wherein The core is the β-AgVO3 nanowire, the middle layer is the Ag _x VO _(2.5+0.5x) (0<x<1) layer produced by losing part of the silver ions on the surface of the β-AgVO3 nanowire, and the outermost layer is the polymer layer. This structure can effectively improve the electrical conductivity of the material, which is beneficial to electron and ion transport; the polymer layer can also act as a buffer layer, effectively preventing the electrode material from being damaged due to volume changes when lithium ions are intercalated/extracted. Improving the cycle stability of electrode materials, and the synergistic effect between inorganic silver vanadium oxides and polymers, also help to improve the electrochemical performance of β-AgVO3. Therefore, the silver vanadium oxide/polymer triaxial nanowires can improve the ability of the material to deintercalate lithium while maintaining a stable and long-term state. Specific capacity and cycle stability; in addition, the simple hydrothermal method used to prepare β-AgVO ₃ nanowires can be controlled by changing the concentration of reactants, reaction temperature and time in an aqueous solution without any surfactant and organic matter The shape and size of the material, and the obtained material has high purity and good dispersibility; in addition, compared with other methods for preparing triaxial nanowires, chemical in-situ polymerization uses water as the medium and undergoes a process at normal temperature and pressure. The synthesis of triaxial nanowires can be realized by stirring for a short time, which meets the requirements of green chemistry and is beneficial to market promotion.

Description of drawings

Figure 1 is the XRD pattern of the silver vanadium oxide/polyaniline triaxial nanowires and β-AgVO ₃ nanowires of Example 1; where Figure 1 (a) is the silver vanadium oxide/polyaniline triaxial nanowires XRD pattern, Figure 1(b) is the XRD pattern of β-AgVO ₃ nanowires;

Fig. 2 is the FTIR picture of the silver vanadium oxide/polyaniline triaxial nanowire and β-AgVO ₃ nanowire of embodiment 1; Wherein Fig. 2 (a) is the silver vanadium oxide/polyaniline triaxial nanowire FTIR diagram, Figure 2(b) is the FTIR diagram of β-AgVO ₃ nanowires;

Fig. 3 is the FESEM figure of the silver vanadium oxide/polyaniline triaxial nanowire of embodiment 1;

Fig. 4 is the TEM figure of the silver vanadium oxide/polyaniline triaxial nanowire of embodiment 1;

Figure 5 is the EDS image of the core and intermediate layer of the silver vanadium oxide/polyaniline triaxial nanowires of Example 1; Figure 5 (a) is the core layer region of the silver vanadium oxide/polyaniline triaxial nanowires The EDS diagram in Fig. 5(b) is the EDS diagram in the middle layer region of silver vanadium oxide/polyaniline triaxial nanowires;

Fig. 6 is the synthetic mechanism diagram of the silver vanadium oxide/polyaniline triaxial nanowire of embodiment 1;

Figure 7 is the battery cycle performance curve of the silver vanadium oxide/polyaniline triaxial nanowires and β-AgVO ₃ nanowires in Example 1, Figure 7 (a) is the silver vanadium oxide/polyaniline triaxial nanowires The battery cycle performance curve of the wire, Figure 7(b) is the battery cycle performance curve of the β-AgVO ₃ nanowire.

Detailed ways

In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

Example 1:

The preparation method of silver vanadium oxide/polyaniline triaxial nanowire, it comprises the steps:

1) Weigh ammonium metavanadate containing 2 mmol of vanadium ions and dissolve in 40 mL of deionized water, then weigh the same amount of silver nitrate and dissolve in 40 mL of deionized water, mix the two solutions under stirring conditions, Continue to stir for 1 hour to obtain the precursor solution for subsequent use;

2) Transfer the precursor solution obtained in step 1) to a 150 mL reactor, react at 180°C for 24 hours, take out the reactor, cool to room temperature naturally, and centrifuge to obtain the precipitate;

3) Wash the obtained precipitate repeatedly with deionized water, and dry it in an oven at 80°C to finally obtain β-AgVO ₃ nanowires for later use;

4) Weigh 0.1 g of the β-AgVO ₃ nanowires obtained in step 3), and disperse them into 20 mL of deionized water after stirring and ultrasonic treatment, slowly inject 0.05 g of aniline monomer under stirring conditions, stir at room temperature for 12 hours, and then Add 20 mL ammonium persulfate aqueous solution with the amount of aniline monomer and other substances under stirring condition, and continue to stir at room temperature for 12 hours;

5) Centrifuge the precipitated product obtained in step 4), wash it repeatedly with deionized water and absolute ethanol until the filtrate is colorless, and then dry it in an oven at 80°C for 12 hours to finally obtain silver vanadium oxide/polyaniline Triaxial nanowires.

The structure of the silver vanadium oxide/polyaniline triaxial nanowire product in Example 1 was determined by X-ray diffractometer and Fourier transform infrared spectrometer. The X-ray diffraction pattern (XRD) shows that the silver _vanadium oxide/polyaniline triaxial nanowires have the same peak positions as the original silver vanadium oxide nanowires. Card 29-1154 matches, as shown in Figure 1; Fourier transform infrared spectroscopy (FTIR) shows the formation of polyaniline, as shown in Figure 2; Field emission scanning electron microscopy (FESEM) tests show that silver vanadium oxide/polyaniline The length of the triaxial nanowire is about 10-30 micrometers, and the diameter is 60-100 nanometers, as shown in Figure 3; the transmission electron microscope (TEM) test can clearly observe the triaxial structure, the thickness of the outermost layer is about 8 nanometers, and the thickness of the middle layer is about 8 nanometers. The thickness of the layer is about 8 nanometers, as shown in Figure 4; the energy dispersive X-ray spectroscopy (EDS) test shows that the core and the middle layer of the silver vanadium oxide/polyaniline triaxial nanowires are composed of Ag, V, O elements, and The content of Ag in the middle layer is less, as shown in Figure 5. This is because the Ag _x VO _(2.5+0.5x) (0<x<1) in the middle layer is formed by the precipitation of Ag ⁺ on the surface of the β-AgVO ₃ nanowire, and Ag ⁺ and aniline monomer occur at the solid-liquid interface The oxidation-reduction reaction produces simple silver, and the presence of silver particles is also found in the transmission electron microscope image, which confirms the occurrence of this reaction; after adding the oxidant, a polyaniline layer is formed, which is coated on the silver vanadium oxide nanowire and formed On the surface of silver particles, triaxial nanowires are formed.

The silver vanadium oxide/polymer triaxial nanowire prepared by the invention is used as the positive electrode active material of the lithium ion battery, and the remaining steps of the preparation method of the lithium ion battery are the same as the usual preparation method. The preparation method of the positive plate is as follows, using silver vanadium oxide/polymer triaxial nanowires as the active material, acetylene black as the conductive agent, polytetrafluoroethylene as the binder, the active material, acetylene black, polytetrafluoroethylene The mass ratio is 70:25:5; after fully mixing them in proportion, add a small amount of isopropanol, grind evenly, and press the electrode sheet with a thickness of about 0.5mm on the roller machine; place the pressed positive electrode sheet in an oven at 80°C After drying for 24 hours, it is ready for use. 1M LiPF6 was dissolved in ethylene carbonate (EC) and dimethyl carbonate (DMC) as electrolyte, lithium sheet was used as negative electrode, celgard2325 was used as separator, and CR2025 stainless steel was used as battery case to assemble a button-type lithium-ion battery.

Taking silver vanadium oxide/polyaniline triaxial nanowires as an example, the constant current charge and discharge test results at a current density of 30mA/g show that its first discharge specific capacity can reach 211mAh/g, and after 20 cycles it is 131 mAh/g, and the capacity retention rate reached 62% after 20 cycles; the discharge specific capacities of β-AgVO ₃ nanowires for the first and 20 cycles were 199 and 76 mAh/g, respectively, and the retention rate was only 41.7%, as shown in Figure 7 shown. The above properties indicate that the silver vanadium oxide/polyaniline triaxial nanowires have significantly improved specific capacity and cycle stability, and are a potential cathode material for lithium-ion batteries.

Example 2:

The preparation method of silver vanadium oxide/polyaniline triaxial nanowire, it comprises the steps:

1) Weigh ammonium metavanadate containing 2 mmol of vanadium ions and dissolve in 40 mL of deionized water, then weigh the same amount of silver acetate and dissolve in 40 mL of deionized water, mix the two solutions under stirring conditions, Continue to stir for 1 hour to obtain the precursor solution for subsequent use;

2) Transfer the precursor solution obtained in step 1) to a 150 mL reactor, react at 160°C for 36 hours, take out the reactor, cool to room temperature naturally, and centrifuge to obtain the precipitate;

3) Wash the obtained precipitate repeatedly with deionized water, and dry it in an oven at 80°C to finally obtain β-AgVO ₃ nanowires for later use;

4) Weigh 0.1 g of β-AgVO ₃ nanowires obtained in step 3), and disperse them into 20 mL of deionized water after stirring and ultrasonic treatment, slowly inject 0.05 g of aniline monomer under stirring conditions, stir at room temperature for 10 hours, and then Under stirring conditions, add 20 mL potassium dichromate aqueous solution with the amount of aniline monomer and other substances, and continue to stir at room temperature for 10 hours;

5) Centrifuge the precipitated product obtained in step 4), wash it repeatedly with deionized water and absolute ethanol until the filtrate is colorless, and then dry it in an oven at 80°C for 12 hours to finally obtain silver vanadium oxide/polyaniline Triaxial nanowires.

Example 3:

The preparation method of silver vanadium oxide/polyaniline triaxial nanowire, it comprises the steps:

1) Weigh vanadium pentoxide sol containing 3 mmol vanadium ions and dissolve it in 40 mL deionized water, then weigh the same amount of silver carbonate and dissolve it in 40 mL deionized water, and mix the two solutions under stirring , and continue to stir for 1 hour to obtain a precursor solution, which is set aside;

2) Transfer the precursor solution obtained in step 1) to a 150 mL reactor, react at 200°C for 12 hours, take out the reactor, cool to room temperature naturally, and centrifuge to obtain the precipitate;

3) Wash the obtained precipitate repeatedly with deionized water, and dry it in an oven at 80°C to finally obtain β-AgVO ₃ nanowires for later use;

4) Weigh 0.1 g of β-AgVO ₃ nanowires obtained in step 3), and disperse them into 20 mL of deionized water after stirring and ultrasonic treatment, slowly inject 0.05 g of aniline monomer under stirring conditions, stir at room temperature for 14 hours, and then Under stirring conditions, add 20 mL of ferric chloride aqueous solution with the amount of aniline monomer and other substances, and continue to stir at room temperature for 14 hours;

5) Centrifuge the precipitated product obtained in step 4), wash it repeatedly with deionized water and absolute ethanol until the filtrate is colorless, and then dry it in an oven at 80°C for 12 hours to finally obtain silver vanadium oxide/polyaniline Triaxial nanowires.

Example 4:

The preparation method of silver vanadium oxide/polypyrrole triaxial nanowire, it comprises the steps:

1) Weigh vanadium pentoxide sol containing 3 mmol vanadium ions and dissolve it in 40 mL deionized water, then weigh the same amount of silver nitrate and dissolve it in 40 mL deionized water, and mix the two solutions under stirring , and continue to stir for 1 hour to obtain a precursor solution, which is set aside;

2) Transfer the precursor solution obtained in step 1) to a 150 mL reactor, react at 180°C for 24 hours, take out the reactor, cool to room temperature naturally, and centrifuge to obtain the precipitate;

3) Wash the obtained precipitate repeatedly with deionized water, and dry it in an oven at 80°C to finally obtain β-AgVO ₃ nanowires for later use;

4) Weigh 0.1 g of the β-AgVO ₃ nanowires obtained in step 3), and disperse them into 20 mL of deionized water after stirring and ultrasonic treatment, slowly inject 0.05 g of pyrrole monomer under stirring conditions, stir at room temperature for 12 hours, and then Add 20 mL ammonium persulfate aqueous solution with the amount of pyrrole monomer and other substances under stirring condition, and continue to stir at room temperature for 12 hours;

5) Centrifuge the precipitated product obtained in step 4), wash it repeatedly with deionized water and absolute ethanol until the filtrate is colorless, and then dry it in an oven at 80°C for 12 hours to finally obtain silver vanadium oxide/polypyrrole Triaxial nanowires.

Example 5:

The preparation method of silver vanadium oxide/polythiophene triaxial nanowire, it comprises the steps:

1) Weigh ammonium metavanadate containing 2.5 mmol of vanadium ions and dissolve in 40 mL of deionized water, then weigh the same amount of silver carbonate and dissolve in 40 mL of deionized water, mix the two solutions under stirring conditions, Continue to stir for 1 hour to obtain the precursor solution for subsequent use;

2) Transfer the precursor solution obtained in step 1) to a 150 mL reactor, react at 180°C for 24 hours, take out the reactor, cool to room temperature naturally, and centrifuge to obtain the precipitate;

3) Wash the obtained precipitate repeatedly with deionized water, and dry it in an oven at 80°C to finally obtain β-AgVO ₃ nanowires for later use;

4) Weigh 0.1 g of β-AgVO ₃ nanowires obtained in step 3), and disperse them into 20 mL of deionized water after stirring and ultrasonic treatment, slowly inject 0.05 g of thiophene monomer under stirring conditions, stir at room temperature for 10 hours, and then Add 20 mL of ammonium persulfate aqueous solution with the amount of thiophene monomer and other substances under stirring conditions, and continue to stir at room temperature for 14 hours;

5) Centrifuge the precipitated product obtained in step 4), wash it repeatedly with deionized water and absolute ethanol until the filtrate is colorless, and then dry it in an oven at 80°C for 12 hours to finally obtain silver vanadium oxide/polythiophene Triaxial nanowires.

Claims (9)

1. silver-vanadium oxide/polymer three co-axial nano lines is characterized in that it has tangible three coaxial configurations, and length is 10 ~ 30 microns, and diameter is the 60-100 nanometer, and its center is β-AgVO ₃Nano wire, intermediate layer are β-AgVO ₃Nanowire surface loses the part silver ion and the silver-vanadium oxide layer that produces, and outermost layer is a polymeric layer, and outermost layer thickness is 6 ~ 10 nanometers, and intermediate layer thickness is 6 ~ 10 nanometers.

2. silver-vanadium oxide/polymer three co-axial nano lines as claimed in claim 1 is characterized in that described polymer is polyaniline, polypyrrole or polythiophene.

3. the preparation method of the described silver-vanadium oxide/polymer three co-axial nano lines of claim 1 is characterized in that including following steps:

1) the vanadium source aqueous solution is mixed under stirring condition with the silver-colored source aqueous solution, obtain precursor solution;

2) step 1) gained precursor solution is transferred to agitated reactor, reacts, naturally cool to room temperature, centrifugal filtration obtains sediment;

3) with deionized water cyclic washing step 2) sediment that obtains, and oven dry obtains β-AgVO ₃Nano wire;

4) with β-AgVO ₃Nano wire is scattered in the deionized water, adds polymer monomer, wherein, and β-AgVO ₃The mass ratio of nano wire and polymer monomer is 2:1, and stirring at room 10-14 hour, the aqueous oxidizing agent solution of amount of substances such as adding and polymer monomer continued stirring at room 10 ~ 14 hours, the centrifugal precipitated product that obtains then;

5) with the precipitated product of deionized water and absolute ethyl alcohol cyclic washing step 4) gained, oven dry obtains silver-vanadium oxide/polymer three co-axial nano lines.

4. the preparation method of silver-vanadium oxide/polymer three co-axial nano lines as claimed in claim 3 is characterized in that described vanadium source is ammonium metavanadate or vanadic oxide colloidal sol.

5. the preparation method of silver-vanadium oxide/polymer three co-axial nano lines as claimed in claim 3 is characterized in that described silver-colored source is silver nitrate, silver acetate or silver carbonate.

6. the preparation method of silver-vanadium oxide/polymer three co-axial nano lines as claimed in claim 3 is characterized in that described polymer monomer is aniline monomer, pyrrole monomer or thiophene monomer.

7. the preparation method of silver-vanadium oxide/polymer three co-axial nano lines as claimed in claim 3 is characterized in that step 2) described reaction temperature is 160 ℃ ~ 200 ℃, the reaction time is 12 ~ 36 hours.

8. silver-vanadium oxide/polymer three co-axial nano line preparation methods as claimed in claim 3 is characterized in that described oxidant is ammonium persulfate, potassium bichromate or ferric trichloride.

9. the described silver-vanadium oxide/polymer three co-axial nano lines of claim 1 are in the application as anode active material of lithium ion battery.

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