CN108417810A - A kind of three-dimensional network structure polyaniline/graphene/silicon composite material preparation method - Google Patents

Abstract

The invention discloses a preparation method of a polyaniline/graphene/silicon composite material with a three-dimensional network structure, which comprises the following steps: adding p-phenylenediamine into water, stirring and dissolving in a water bath, adding a silicon source, stirring and dispersing, adding graphene oxide, uniformly dispersing, and carrying out hydrothermal reaction to obtain hydrogel M1; adding hydrogel M1 into hydrochloric acid for precooling, and adding NaNO₂Solution and HBF₄Respectively precooling the solution, and dropwise adding precooled NaNO into hydrochloric acid containing hydrogel M1 in an ice water bath₂Solution and precooled HBF₄Carrying out solution and then carrying out diazotization reaction to obtain hydrogel M2; dissolving aniline monomer in sulfuric acid solutionAdding hydrogel M2, soaking, and precooling to obtain a first mixed solution; dissolving ammonium persulfate in a sulfuric acid solution, and precooling to obtain a second mixed solution; and dropwise adding the second mixed solution into the first mixed solution in an ice-water bath, and adjusting the temperature to perform polymerization reaction to obtain the polyaniline/graphene/silicon composite material with the three-dimensional network structure.

Description

A kind of three-dimensional network structure polyaniline/graphene/silicon composite material preparation method

technical field

The invention relates to the technical field of lithium ion batteries, in particular to a method for preparing a polyaniline/graphene/silicon composite material with a three-dimensional network structure.

Background technique

With the development of electric vehicles and portable appliances, the demand for lithium-ion batteries with high energy density is also increasing. The theoretical specific capacity of traditional graphite anode materials is only 372mAh/g, which is difficult to meet market demand. The first gram capacity of silicon materials is 4200mAh/g, the lithium intercalation platform is higher, the earth's crust is abundant, and it is environmentally friendly, which has gradually attracted widespread attention of researchers.

However, the volume expansion of silicon is as high as 300%. During the cycle, it will not only cause silicon to separate from the surrounding conductive carbon network to form "dead silicon", but also cause silicon to peel off from the current collector. Secondly, the large volume expansion will also lead to the continuous reorganization and destruction of the SEI film on the surface, making the SEI film thicker and thicker, continuously consuming the Li ⁺ of the positive electrode, and reducing the Coulombic efficiency. Finally, the large volume expansion leads to pulverization of the silicon material in the late cycle, and these problems eventually lead to a sharp deterioration of the cycle performance.

At present, researchers mainly solve the above problems by compounding silicon with carbon materials, compounding with metal materials or using silicon oxide. In terms of metal silicon alloy, it is mainly combined with Al, Ti, Mg and other metals to buffer the volume expansion of the material, which can greatly improve the cycle performance of silicon. broken, the performance drops sharply. In terms of silicon-carbon materials, silicon materials and carbon materials are mainly used to improve the shortcomings of silicon materials by means of solid/liquid phase mixing, liquid phase coating, spray drying granulation, high-temperature sintering, etc., which can not only improve the electrical conductivity of the material, The volume expansion of the buffer material improves the cycle stability of the material to a certain extent. In addition, there are some studies on silicon oxide materials. Compared with silicon materials, its gram capacity is reduced, but its cycle performance is improved. The biggest problem is that the first effect is low, only 65-70%. In actual use, it needs to be pre-lithiated. However, the pre-lithiated process is not yet mature, and it is currently used after being mixed with graphite.

Contents of the invention

Based on the technical problems existing in the background technology, the present invention proposes a method for preparing a three-dimensional network structure polyaniline/graphene/silicon composite material, which overcomes the defects in the prior art, can effectively buffer the volume expansion of silicon, and improve the electronic and ion conductivity of the material The obtained composite material has a three-dimensional network structure, which not only provides a path for the transmission of lithium ions, but also buffers the volume deformation of the silicon material during charge and discharge. In addition, polyaniline can not only improve the interface performance of the material, but also has a chain structure in the composite material, providing electron and ion channels between silicon particles during charge and discharge. Finally, graphene and polyaniline can also improve the electronic conductivity of silicon materials, reduce material polarization, and improve the cycle stability of silicon-based materials to a certain extent.

A kind of three-dimensional network structure polyaniline/graphene/silicon composite material preparation method that the present invention proposes, comprises the following steps:

S1. Add p-phenylenediamine to deionized water, stir and dissolve in a water bath, then add silicon source to stir and disperse, then add graphene oxide to disperse evenly, and then perform hydrothermal reaction to obtain hydrogel M1;

S2. Add the hydrogel M1 to hydrochloric acid to pre-cool, then pre-cool the _NaNO2 solution and the _HBF4 solution respectively, and add the pre-cooled NaNO2 solution and the pre-cooled hydrogel M1 dropwise to the hydrochloric acid containing the hydrogel M1 in _an ice-water bath. The cooled HBF ₄ solution is then subjected to a diazotization reaction and washed with deionized water to obtain the hydrogel M2;

S3, dissolving aniline monomer in sulfuric acid solution, then adding hydrogel M2, soaking, and pre-cooling to obtain the first mixed solution; dissolving ammonium persulfate in sulfuric acid solution, and pre-cooling to obtain the second mixed solution; The second mixed solution is added dropwise to the first mixed solution in a water bath, the temperature is adjusted to carry out polymerization reaction, washed with sulfuric acid solution, and dried to obtain a polyaniline/graphene/silicon composite material with a three-dimensional network structure.

Preferably, in S1, the silicon source is at least one of nano-silicon particles, silicon nanowires, silicon nano-films, and silicon oxide.

Preferably, in S1, the mass ratio of p-phenylenediamine to graphene oxide is 8˜12:1.

Preferably, in S1, the mass ratio of silicon source to graphene oxide is 7˜57:3.

Preferably, in S1, the temperature of the water bath is 50-90°C.

Preferably, in S1, the hydrothermal reaction temperature is 120-200° C., and the hydrothermal reaction time is 0.5-10 h.

Preferably, in S2, the pre-cooling temperature is 0°C.

Preferably, in S2, the concentration of hydrochloric acid is 0.8-1.2 mol/L.

Preferably, in S2, the mass ratio of NaNO ₂ in the NaNO ₂ solution to HBF ₄ in the HBF ₄ solution is 1:1-4.

Preferably, in S2, the diazotization reaction temperature is -10-20° C., and the diazotization reaction time is 0.5-4 h.

Preferably, in S3, the soaking time is 2-10 hours.

Preferably, in S3, the pre-cooling temperature is 0°C.

Preferably, in S3, the molar ratio of aniline monomer to ammonium persulfate is 1:1-4.

Preferably, in S3, the concentration of the sulfuric acid solution is 0.4-0.6 mol/L.

Preferably, in S3, the polymerization reaction temperature is -10-20° C., and the polymerization reaction time is 2-12 hours.

Preferably, in S3, the drying temperature is 60-100°C.

Compared with the prior art, the present invention has the advantages of:

(1) The polyaniline/graphene/silicon composite material obtained in the present invention has a three-dimensional network structure, which can not only buffer the volume expansion of silicon-based materials during charging and discharging, but also provide channels for the rapid transmission of lithium ions;

(2) The polyaniline used in the present invention can not only improve the interface performance of the material, but also improve the interface stability, and because it is in a chain structure, even if some silicon particles are broken during the charging and discharging process, it can still provide electrons and ion channels. Greatly improved the cycle performance of the material;

(3) The present invention adopts graphene and polyaniline to improve the electronic conductivity of silicon-based materials, reduce material polarization, and improve the rate performance of materials;

(4) The method of the present invention is simple, easy to control and realize industrial operation, and the obtained polyaniline/graphene/silicon composite material has good cycle stability and rate performance.

Description of drawings

Figure 1 is an SEM image of the polyaniline/graphene/silicon composite material obtained in Example 1 of the present invention.

Fig. 2 is a TEM image of the polyaniline/graphene/silicon composite material obtained in Example 1 of the present invention at a low resolution.

Fig. 3 is a TEM image of the polyaniline/graphene/silicon composite material obtained in Example 1 of the present invention at high resolution.

Fig. 4 is the first charge and discharge curves of the polyaniline/graphene/silicon composite material obtained in Example 1 of the present invention and the comparative example.

Fig. 5 is a diagram of the cycle performance of the polyaniline/graphene/silicon composite material obtained in Example 1 of the present invention and the comparative example at a current density of 0.1C.

Detailed ways

Below, the technical solution of the present invention will be described in detail through specific examples.

Example 1

A method for preparing a three-dimensional network structure polyaniline/graphene/silicon composite material, comprising the steps of:

S1. Add 0.288g of p-phenylenediamine to 100mL of deionized water, stir and dissolve in a water bath at 60°C, then add 0.684g of nano-silicon for stirring and dispersing, then add 12mL of graphene oxide dispersion with a mass fraction of 3mg/mL, and disperse evenly. Then carry out hydrothermal reaction, the hydrothermal reaction temperature is 180°C, and the hydrothermal reaction time is 2h, to obtain the hydrogel M1;

S2. Add hydrogel M1 into 100mL hydrochloric acid with a concentration of 1mol/L to pre-cool to 0°C; then add 0.2g _NaNO2 into 4mL deionized water, measure _8mL HBF4 solution with a mass fraction of 14wt%, and mix the two were pre-cooled to 0°C; in an ice-water bath, pre-cooled NaNO ₂ solution and pre-cooled HBF ₄ solution were added dropwise to the hydrochloric acid containing hydrogel M1, and then the diazotization reaction was carried out. The temperature is 0°C, the diazotization reaction time is 2 hours, and the hydrogel M2 is obtained by washing with deionized water;

S3. Dissolve 10 mL of aniline monomer with a molar concentration of 0.01 mol/L in a sulfuric acid solution with a concentration of 0.5 mol/L, then add hydrogel M2, soak for 7 hours, and pre-cool to 0°C to obtain the first mixed solution; Dissolve 0.03g of ammonium persulfate in 3mL of sulfuric acid solution with a molar concentration of 0.5mol/L, and pre-cool to 0°C to obtain the second mixed solution; add the second mixed solution dropwise to the first mixed solution in an ice-water bath, Then carry out the polymerization reaction, the polymerization reaction temperature is 0°C, the polymerization reaction time is 6h, the sulfuric acid solution is washed 3 to 5 times, and placed in an 80°C oven to dry completely to obtain a three-dimensional network structure polyaniline/graphene/silicon composite material.

Fig. 1 is the SEM picture of polyaniline/graphene/silicon composite material obtained in the present embodiment, can find from Fig. 1: graphene is three-dimensional network structure, and nano-silicon is dispersed in the three-dimensional network channel of graphene. And Fig. 2 is the TEM picture of the polyaniline/graphene/silicon composite material obtained in Example 1 of the present invention at low resolution magnification, and Fig. 3 is the polyaniline/graphene/silicon composite material obtained in Example 1 of the present invention at high resolution magnification The following TEM images can be found from Figure 2 and Figure 3: the size of nano-silicon particles is about 50-80nm, and they are evenly distributed on the surface of graphene.

The polyaniline/graphene/silicon composite material, Super-P, and LA133 obtained in this example were subjected to grinding, slurry mixing, and coating according to 8:1:1, and a button-type CR2016 battery was assembled, and EC+DMC with 1mol/L LiPF6 was selected The solution was used as the electrolyte for electrochemical performance testing.

Example 2

A method for preparing a three-dimensional network structure polyaniline/graphene/silicon composite material, comprising the steps of:

S1. Add 0.432g of p-phenylenediamine to 100mL of deionized water, stir and dissolve in a water bath at 50°C, then add 0.684g of silicon nanowires for stirring and dispersing, then add 12mL of graphene oxide dispersion with a mass fraction of 3mg/mL, and disperse evenly , and then carry out hydrothermal reaction, the hydrothermal reaction temperature is 120°C, the hydrothermal reaction time is 0.5h, and the hydrogel M1 is obtained;

S2. Add hydrogel M1 into 100mL hydrochloric acid with a concentration of 1mol/L to pre-cool to 0°C; then add 0.2g NaNO ₂ into 4mL deionized water, measure 32mL HBF ₄ solution with a mass fraction of 4wt%, and mix the two were pre-cooled to 0°C; in an ice-water bath, pre-cooled NaNO ₂ solution and pre-cooled HBF ₄ solution were added dropwise to the hydrochloric acid containing hydrogel M1, and then the diazotization reaction was carried out. The temperature is 0°C, the diazotization reaction time is 4 hours, and the hydrogel M2 is obtained by washing with deionized water;

S3. Dissolve 10 mL of aniline monomer with a molar concentration of 0.01 mol/L in a sulfuric acid solution with a concentration of 0.5 mol/L, then add hydrogel M2, soak for 7 hours, and pre-cool to 0°C to obtain the first mixed solution; Dissolve 0.03g of ammonium persulfate in 3mL of sulfuric acid solution with a molar concentration of 0.5mol/L, and pre-cool to 0°C to obtain the second mixed solution; add the second mixed solution dropwise to the first mixed solution in an ice-water bath, Then carry out the polymerization reaction, the polymerization reaction temperature is 0°C, the polymerization reaction time is 12h, the sulfuric acid solution is washed 3 to 5 times, and placed in a 100°C oven to dry completely to obtain a three-dimensional network structure polyaniline/graphene/silicon composite material.

Example 3

A method for preparing a three-dimensional network structure polyaniline/graphene/silicon composite material, comprising the steps of:

S1. Add 0.432g of p-phenylenediamine to 100mL of deionized water, stir and dissolve in a water bath at 50°C, then add 0.684g of silicon oxide to stir and disperse, then add 12mL of graphene oxide dispersion with a mass fraction of 3mg/mL, and disperse evenly , and then carry out hydrothermal reaction, the hydrothermal reaction temperature is 120°C, the hydrothermal reaction time is 0.5h, and the hydrogel M1 is obtained;

S2. Add hydrogel M1 into 100mL hydrochloric acid with a concentration of 1mol/L to pre-cool to 0°C; then add 0.2g NaNO ₂ into 4mL deionized water, measure 32mL HBF ₄ solution with a mass fraction of 4wt%, and mix the two The two were pre-cooled to 0°C respectively; the pre-cooled NaNO ₂ solution and the pre-cooled HBF ₄ solution were added dropwise to the hydrochloric acid containing hydrogel M1 in an ice-water bath, and then the diazotization reaction was carried out. The temperature is 0°C, the diazotization reaction time is 0.5h, and the hydrogel M2 is obtained by washing with deionized water;

S3. Dissolve 10 mL of aniline monomer with a molar concentration of 0.01 mol/L in a sulfuric acid solution with a concentration of 0.5 mol/L, then add hydrogel M2, soak for 6 hours, and pre-cool to 0°C to obtain the first mixed solution; Dissolve 0.023g of ammonium persulfate in 3mL of sulfuric acid solution with a molar concentration of 0.5mol/L, pre-cool to 0°C to obtain the second mixed solution; add the second mixed solution dropwise to the first mixed solution in an ice-water bath, Then carry out the polymerization reaction, the polymerization reaction temperature is 0°C, the polymerization reaction time is 2h, the sulfuric acid solution is washed 3 to 5 times, and placed in a 60°C oven to dry completely to obtain a three-dimensional network structure polyaniline/graphene/silicon composite material.

Example 4

A method for preparing a three-dimensional network structure polyaniline/graphene/silicon composite material, comprising the steps of:

S1. Add 0.288g of p-phenylenediamine to 100mL of deionized water, stir and dissolve in a water bath at 50°C, then add 0.684g of silicon oxide to stir and disperse, then add 12mL of graphene oxide dispersion with a mass fraction of 3mg/mL, and disperse evenly , and then carry out hydrothermal reaction, the hydrothermal reaction temperature is 120°C, the hydrothermal reaction time is 0.5h, and the hydrogel M1 is obtained;

S2. Add hydrogel M1 into 100mL hydrochloric acid with a concentration of 1mol/L to pre-cool to 0°C; then add 0.2g NaNO ₂ into 4mL deionized water, measure 32mL HBF ₄ solution with a mass fraction of 4wt%, and mix the two were pre-cooled to 0°C; in an ice-water bath, pre-cooled NaNO ₂ solution and pre-cooled HBF ₄ solution were added dropwise to the hydrochloric acid containing hydrogel M1, and then the diazotization reaction was carried out. The temperature is 0°C, the diazotization reaction time is 0.5h, and the hydrogel M2 is obtained by washing with deionized water;

S3. Dissolve 10 mL of aniline monomer with a molar concentration of 0.01 mol/L in a sulfuric acid solution with a concentration of 0.5 mol/L, then add hydrogel M2, soak for 6 hours, and pre-cool to 0°C to obtain the first mixed solution; Dissolve 0.023g of ammonium persulfate in 3mL of sulfuric acid solution with a molar concentration of 0.5mol/L, pre-cool to 0°C to obtain the second mixed solution; add the second mixed solution dropwise to the first mixed solution in an ice-water bath, Then carry out the polymerization reaction, the polymerization reaction temperature is 0°C, the polymerization reaction time is 2h, the sulfuric acid solution is washed 3 to 5 times, and placed in a 60°C oven to dry completely to obtain a three-dimensional network structure polyaniline/graphene/silicon composite material.

comparative example

Nano-silicon, Super-P, and LA133 were ground, slurried, and coated according to 8:1:1, and the button-type CR2016 battery was assembled. The EC+DMC solution of 1mol/L LiPF6 was selected as the electrolyte for electrochemical performance testing.

Figure 4 and Figure 5 are the first charge and discharge curves and cycle performance diagrams of the materials prepared in Example 1 and Comparative Example. Under the current density of 0.1C, the first charge specific capacity of polyaniline/graphene/silicon composite material obtained in the present invention is 2685mAh/g, the first effect is 85%, the charge specific capacity of the material after 50 weeks is 2499mAh/g, and the capacity retention rate It is 93%; the first charging specific capacity of the nano-silicon material used in the comparative example is 2244mAh/g, the first coulombic efficiency is 61.7%, and the specific capacity after 30 cycles is only 300mAh/g, which proves that the polyaniline with the three-dimensional network structure obtained by the present invention /graphene/silicon composites have greatly improved cycle stability.

The above-mentioned improvement in electrical properties is due to the three-dimensional network structure of the polyaniline/graphene/silicon composite material, which not only provides a path for the transmission of lithium ions, but also buffers the volume deformation of the silicon material during charge and discharge. In addition, polyaniline can not only improve the interface performance of the material, but also has a chain structure in the composite material, providing electron and ion channels between silicon particles during charge and discharge. Finally, graphene and polyaniline can also improve the electronic conductivity of silicon materials, reduce material polarization, and improve the cycle stability of silicon-based materials to a certain extent.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concepts thereof shall fall within the protection scope of the present invention.

Claims (10)

1. a three-dimensional network structure polyaniline/graphene/silicon composite material preparation method, is characterized in that, comprises the steps: S1. Add p-phenylenediamine to deionized water, stir and dissolve in a water bath, then add silicon source to stir and disperse, then add graphene oxide to disperse evenly, and then perform hydrothermal reaction to obtain hydrogel M1; S2. Add the hydrogel M1 to hydrochloric acid to pre-cool, then pre-cool the _NaNO2 solution and the _HBF4 solution respectively, and add the pre-cooled NaNO2 solution and the pre-cooled hydrogel M1 dropwise to the hydrochloric acid containing the hydrogel M1 in _an ice-water bath. Cooled HBF ₄ solution, then carry out diazotization reaction to obtain hydrogel M2; S3, dissolving aniline monomer in sulfuric acid solution, then adding hydrogel M2, soaking, and pre-cooling to obtain the first mixed solution; dissolving ammonium persulfate in sulfuric acid solution, and pre-cooling to obtain the second mixed solution; The second mixed solution is added dropwise to the first mixed solution in a water bath, and the temperature is adjusted to carry out a polymerization reaction to obtain a polyaniline/graphene/silicon composite material with a three-dimensional network structure. 2. according to the described three-dimensional network structure polyaniline/graphene/silicon composite material preparation method of claim 1, it is characterized in that, in S1, silicon source is at least in nano-silicon particle, silicon nanowire, silicon nano-film, silicon oxide A sort of. 3. According to the preparation method of the three-dimensional network structure polyaniline/graphene/silicon composite material according to claim 1 or 2, it is characterized in that, in S1, the mass ratio of p-phenylenediamine to graphene oxide is 8 to 12:1; Preferably, in S1, the mass ratio of silicon source to graphene oxide is 7˜57:3. 4. The preparation method of the three-dimensional network structure polyaniline/graphene/silicon composite material according to any one of claims 1-3, characterized in that, in S1, the temperature of the water bath is 50-90°C; preferably, in S1, the water bath The thermal reaction temperature is 120-200°C, and the hydrothermal reaction time is 0.5-10h. 5. According to the preparation method of the three-dimensional network structure polyaniline/graphene/silicon composite material according to any one of claims 1-4, it is characterized in that, in S2, the precooling temperature is 0°C; preferably, in S2, the hydrochloric acid concentration 0.8~1.2mol/L. 6. according to _claim 1-5 any one _described three-dimensional network structure polyaniline/graphene/silicon composite material preparation method, it is characterized in that, in S2, NaNO in solution _{NaNO in} solution and HBF in solution HBF ₄ quality The ratio is 1:1~4. 7. The preparation method of the three-dimensional network structure polyaniline/graphene/silicon composite material according to any one of claims 1-6, characterized in that, in S2, the diazotization reaction temperature is -10 to 20°C, and the diazotization The reaction time is 0.5~4h. 8. The method for preparing a three-dimensional network structure polyaniline/graphene/silicon composite material according to any one of claims 1-7, characterized in that, in S3, the soaking time is 2 to 10 h; preferably, in S3, pre-cooling The temperature is 0°C. 9. According to the preparation method of three-dimensional network structure polyaniline/graphene/silicon composite material according to any one of claims 1-8, it is characterized in that, in S3, the molar ratio of aniline monomer to ammonium persulfate is 1:1～ 4; Preferably, in S3, the concentration of the sulfuric acid solution is 0.4-0.6 mol/L. 10. The preparation method of the three-dimensional network structure polyaniline/graphene/silicon composite material according to any one of claims 1-9, characterized in that, in S3, the polymerization reaction temperature is -10 to 20°C, and the polymerization reaction time is 2 ~12h.