CN110581270A - A kind of preparation method and application of hollow nano-silicon ball anode material - Google Patents

Abstract

The invention relates to a preparation method and application of a hollow nano-silicon ball negative electrode material, which specifically includes the following steps: S1: adding cetylamine bromide, sodium dodecyl sulfate, ammonia water, anhydrous ethanol and ultrapure water Mix and add tetraethyl orthosilicate to perform a sol-gel reaction to obtain a white powder. S2: After the white powder was incubated, it was washed with acidic anhydrous ethanol and dried to obtain hollow silica after calcination. S3: fully grind the hollow silica with magnesium powder, sodium chloride, potassium chloride, etc., mix, and calcine to obtain a brown mixture. S4: After the brown mixture is washed with hydrochloric acid and hydrofluoric acid and dried, hollow nano-silicon spheres are obtained. After testing, at a current density of 1.0A/g, the hollow nano-silicon spheres still have a capacity of 1200mAh/g after 100 cycles, which is much higher than that of ordinary silicon (only 400mAh/g remains after 100 cycles). The hollow nano-silicon spheres can significantly improve the cycling stability of silicon anode materials.

Description

A kind of preparation method and application of hollow nano-silicon ball anode material

technical field

The invention belongs to the technical field of negative electrode materials for lithium ion batteries, and particularly relates to a preparation method of hollow nano-silicon spheres and its application in the preparation of negative electrode materials for lithium ion batteries.

Background technique

Silicon is abundant on Earth and has a wide range of applications in semiconductors and energy. The theoretical capacity of silicon is 4200mAh•g ^-1 , which is much higher than that of the traditional graphite anode. It is expected to become the anode material of a new generation of lithium-ion batteries. However, there is a large volume expansion in the lithiation process of silicon, which causes the continuous rupture and growth of the SEI film, resulting in a low first effect and poor cycle performance. At present, there are two main methods to improve the performance of silicon anode materials, one is to coat the surface of silicon, and the other is to design silicon with different microstructures.

Chinese patent application 201910072699.5 discloses a double-layered silicon anode material structure on the surface, and the surface of silicon particles is sequentially coated with a silicon nitride layer and a silicon oxide layer from the inside to the outside. The inner silicon nitride layer can be used to limit the lithium storage expansion of the silicon material, and the Si-O bond in the outer silicon oxide layer can be combined with the carbon-hydrogen-oxygen structure in the binder to form a chemical bond to play an elastic nail. Binding effect, thereby improving the cycle stability of lithium-ion batteries. At the same time, due to the existence of the inner silicon nitride layer, the function of the outer silicon oxide layer is only to combine with the binder to form a pinning effect, so its thickness can be thinner, and it will not produce too much irreversible during the lithium storage process. Oxides, the first coulombic efficiency of silicon anode materials will not be greatly affected. Therefore, the silicon oxide and silicon nitride double-layer-coated silicon anode material structure is expected to have high specific capacity, excellent cycle stability and high first Coulombic efficiency at the same time.

Chinese patent application 201810797037.X discloses a silicon-based negative electrode material, including several silicon nanoparticles and a binder, each silicon nanoparticle is connected to each other by the binder, and the binder includes citric acid and a macromolecular chain polymer, The citric acid is coated on the surface of the silicon nanoparticle, and the macromolecular chain polymer is connected with the citric acid on the surface of the silicon nanoparticle. Using the synergistic effect of the macromolecular chain polymer and the double binder of CA, a three-dimensional cross-linked structure is formed as the binder of the silicon-based negative electrode material, and the structural stability of the electrode material is enhanced.

Chinese patent application 201710856095.0 discloses a novel silicon micro-nano structure preparation technology, which combines metal-induced silicon oxidation and acid-base corrosion to propose a low-cost, high-efficiency large-area periodic silicon micro-nano structure array preparation method . The pattern of the silicon micro-nano structure is not only determined by the pattern of the micro-nano structure on the lithography template, but also determined by the type of etchant used. The preparation method has a simple process, low requirements on equipment, and can efficiently prepare periodic silicon micro-nano structure arrays, such as micro-structures such as silicon micro-nano holes, positive pyramids, and inverted pyramids. The method is simple in process and low in cost, and the prepared large-area silicon micro-nano structure array has wide application prospects in the fields of solar cells, sensors and the like.

There is no report in the prior art that nano-silicon spheres with a hollow structure are prepared by a sol-gel method combined with magnesium thermal reduction, thereby effectively improving the cycle performance of silicon anode materials.

SUMMARY OF THE INVENTION

In order to solve the problems raised in the prior art, the present invention proposes a preparation method and application of a hollow nano-silicon ball negative electrode material. The prepared hollow structure can provide space for the volume expansion of silicon and shorten the transmission of lithium ions at the same time. It is an improved way to effectively improve the cycle performance of silicon anode materials.

The present invention adopts the following technical scheme: a preparation method of a hollow nano-silicon sphere negative electrode material, the hollow silicon dioxide is prepared by a sol-gel method, and is subjected to magnesium thermal reduction to obtain the hollow nano-silicon sphere.

In a preferred embodiment of the present invention, the preparation method specifically comprises the following steps:

S1: mix cetyl amine bromide, sodium lauryl sulfate, ammonia water, dehydrated alcohol and water and add tetraethyl orthosilicate to carry out sol-gel reaction to obtain white powder;

S2: after incubating the obtained white powder in water, washing and drying with acidic absolute ethanol, and calcining to obtain hollow silica;

S3: fully grind the hollow silica with magnesium powder, sodium chloride, potassium chloride, etc., mix, and calcine to obtain a brown mixture;

S4: After the brown mixture is washed with hydrochloric acid and hydrofluoric acid and dried, hollow nano-silicon spheres are obtained.

Preferably, the specific operation of S1 is: dissolving cetyl ammonium bromide and sodium dodecyl sulfate in a mixed solution of ultrapure water and absolute ethanol, adding ammonia water, stirring, and adding dropwise to the mixed solution Add tetraethyl orthosilicate, stir and filter to obtain white powder.

Preferably, in the specific operation of S1, the reaction temperature is 30-35°C.

Preferably, in the specific operation of S1, the stirring rate is 500-800 rpm.

Preferably, in the specific operation of S1, the reaction time is 20-30h.

Preferably, in the specific operation of S1, the mass-volume (g/L) ratio of cetylammonium bromide, sodium dodecyl sulfate and water is 1.5-3.5:1.5-3.5:0.5-2.

Preferably, in the specific operation of S1, the volume ratio of ammonia water, tetraethyl orthosilicate, absolute ethanol, and water is: 0.5-1.5:0.5-1.2:25-40:35-60.

Preferably, in the specific operation of S1, the concentration of ammonia water is 28wt%.

Preferably, in the specific operation of S2, the white powder is incubated in ultrapure water.

Preferably, in the specific operation of S2, the incubation temperature is 65-90°C.

Preferably, in the specific operation of S2, the incubation time is 24h-72h.

Preferably, in the specific operation of S2, cleaning is performed in absolute ethanol, and 0.2-0.5 ml of hydrochloric acid is added.

Preferably, in the specific operation of S2, the cleaning temperature is 60-70°C.

Preferably, in the specific operation of S2, the cleaning time is 6-12h.

Preferably, in the specific operation of S2, the drying temperature is 80°C and the drying time is 12h.

Preferably, in the specific operation of S2, calcination is carried out in air.

Preferably, in the specific operation of S2, the calcination temperature is 450-600°C.

Preferably, in the specific operation of S2, the calcination time is 4-8h.

Preferably, in the specific operation of S3, the mass ratio of hollow silica, magnesium powder, sodium chloride and potassium chloride is 1:0.8-1.5:5-10:5-10.

Preferably, in the specific operation of S3, the grinding time is not specified, and the mixing is uniform.

Preferably, in the specific operation of S3, the magnesium thermal reduction reaction is carried out in an argon atmosphere.

Preferably, in the specific operation of S3, the temperature of the magnesium thermal reduction reaction is 650°C-700°C.

Preferably, in the specific operation of S3, the heating rate is 1-10°C/min.

Preferably, in the specific operation of S3, the holding time is 2.5-4h.

Preferably, in the specific operation of S4, the concentration of hydrochloric acid is 1-3 mol/L.

Preferably, in the specific operation of S4, the cleaning time of hydrochloric acid is 5-12h.

Preferably, in the specific operation of S4, the concentration of hydrofluoric acid is 5-10 wt%.

Preferably, in the specific operation of S4, the cleaning time of hydrofluoric acid is 1-3h.

Preferably, in the specific operation of S4, the drying method is vacuum drying.

Preferably, in the specific operation of S4, the drying time is 12-24h.

The invention also protects the application of the hollow nano-silicon spheres in the negative electrode material of lithium ion batteries.

Compared with the prior art, the present invention adopts the sol-gel method combined with the method of magnesium thermal reduction to prepare nano-silicon spheres with hollow structure for the first time, and the prepared hollow nano-silicon spheres provide space for the volume change of the silicon material during the lithiation process. , shortens the path of lithium ion transmission, and effectively improves the cycle stability of silicon. The preparation method of the present invention is simple and easy to implement, can expand production, and also provides the preparation of hollow nano-silicon spheres that can be used as negative electrode materials for lithium ion batteries. a feasible preparation route.

Description of drawings

Further description is made below in conjunction with the accompanying drawings:

Fig. 1 is the TEM picture of the hollow silica of embodiment 3;

Fig. 2 is the TEM picture of the hollow nano-silicon sphere of embodiment 3;

FIG. 3 shows the test results of the charge-discharge performance and cycle performance of the hollow nano-silicon spheres of Example 3. FIG.

Detailed ways

Further description will be given below in conjunction with the embodiments.

Example 1

S1: Cetylamine bromide, sodium lauryl sulfate, ammonia water, absolute ethanol, and ultrapure water are mixed, and tetraethyl orthosilicate is added to carry out a sol-gel reaction to obtain a white powder.

S2: After the white powder was incubated, it was washed with acidic anhydrous ethanol and dried to obtain hollow silica after calcination.

S3: fully grind the hollow silica with magnesium powder, sodium chloride, potassium chloride, etc., mix, and calcine to obtain a brown mixture.

S4: After the brown mixture is washed with hydrochloric acid and hydrofluoric acid and dried, hollow nano-silicon spheres are obtained.

Wherein, the specific operation of S1 is: dissolving cetyl ammonium bromide and sodium dodecyl sulfate in a mixed solution of ultrapure water and absolute ethanol, adding ammonia water, and stirring. Tetraethyl orthosilicate is added dropwise to the mixed solution, stirred and filtered to obtain a white powder. The obtained white powder is incubated, washed, dried and calcined to obtain hollow silica.

In the specific operation of S1, the reaction temperature was 35°C.

In the specific operation of S1, the stirring rate was 600 rpm.

In the specific operation of S1, the reaction time is 20h.

In the specific operation of S1, the mass-volume (g/L) ratio of cetylammonium bromide, sodium dodecyl sulfate and water is 3:3:1.

In the specific operation of S1, the volume ratio of ammonia water, tetraethyl orthosilicate, absolute ethanol, and water is: 1.5:1:30:50.

In the specific operation of S1, the concentration of ammonia water is 28wt%.

In the specific operation of S2, the white powder was incubated in ultrapure water.

In the specific operation of S2, the incubation temperature was 80°C.

In the specific operation of S2, the incubation time was 36h.

In the specific operation of S2, wash in absolute ethanol, and add 0.3 ml of hydrochloric acid.

In the specific operation of S2, the cleaning temperature was 60°C.

In the specific operation of S2, the cleaning time is 10h.

In the specific operation of S2, the drying temperature is 80°C and the drying time is 12h.

In the specific operation of S2, calcination is carried out in air.

In the specific operation of S2, the calcination temperature is 550°C.

In the specific operation of S2, the calcination time is 6h.

The particle size of the hollow silica obtained in S2 was 450 nm.

In the specific operation of S3, the mass ratio of hollow silica, magnesium powder, sodium chloride and potassium chloride is 1:1:5:5.

In the specific operation of S3, the grinding time is not specified, and the mixing can be uniform.

In the specific operation of S3, the magnesium thermal reduction reaction is carried out in an argon atmosphere.

In the specific operation of S3, the temperature of the magnesium thermal reduction reaction is 700°C.

In the specific operation of S3, the heating rate was 5°C/min.

In the specific operation of S3, the holding time is 3h.

In the specific operation of S4, the concentration of hydrochloric acid was 1.5 mol/L.

In the specific operation of S4, the cleaning time of hydrochloric acid is 10h.

In the specific operation of S4, the concentration of hydrofluoric acid is 5wt%.

In the specific operation of S4, the cleaning time of hydrofluoric acid is 1h.

In the specific operation of S4, the drying method is vacuum drying.

In the specific operation of S4, the drying time was 18h.

The particle size of the hollow silicon microspheres obtained in S4 is about 450 nm.

Example 2

A preparation method of hollow nano-silicon ball, comprising the following steps

S1: Cetylamine bromide, sodium lauryl sulfate, ammonia water, absolute ethanol, and ultrapure water are mixed, and tetraethyl orthosilicate is added to carry out a sol-gel reaction to obtain a white powder.

S2: After the white powder was incubated, it was washed with acidic anhydrous ethanol and dried to obtain hollow silica after calcination.

S3: fully grind the hollow silica with magnesium powder, sodium chloride, potassium chloride, etc., mix, and calcine to obtain a brown mixture.

S4: After the brown mixture is washed with hydrochloric acid and hydrofluoric acid and dried, hollow nano-silicon spheres are obtained.

Wherein, the specific operation of S1 is: dissolving cetyl ammonium bromide and sodium dodecyl sulfate in a mixed solution of ultrapure water and absolute ethanol, adding ammonia water, and stirring. Tetraethyl orthosilicate is added dropwise to the mixed solution, stirred and filtered to obtain a white powder. The obtained white powder is incubated, washed, dried and calcined to obtain hollow silica.

In the specific operation of S1, the reaction temperature was 30°C.

In the specific operation of S1, the stirring rate was 500 rpm.

In the specific operation of S1, the reaction time is 24h.

In the specific operation of S1, the mass-volume (g/L) ratio of cetylammonium bromide, sodium dodecyl sulfate and water is 2:2:1.

In the specific operation of S1, the volume ratio of ammonia water, tetraethyl orthosilicate, absolute ethanol, and water is: 0.5:0.5:25:35.

In the specific operation of S1, the concentration of ammonia water is 28wt%

In the specific operation of S2, the white powder was incubated in ultrapure water.

In the specific operation of S2, the incubation temperature was 90°C.

In the specific operation of S2, the incubation time was 24h.

In the specific operation of S2, wash in absolute ethanol, and add 0.2 ml of hydrochloric acid.

In the specific operation of S2, the cleaning temperature was 60°C.

In the specific operation of S2, the cleaning time is 6h.

In the specific operation of S2, the drying temperature is 80°C and the drying time is 12h.

In the specific operation of S2, calcination is carried out in air.

In the specific operation of S2, the calcination temperature is 500°C.

In the specific operation of S2, the calcination time is 8h.

The particle size of the hollow silica obtained in S2 was 450 nm.

In the specific operation of S3, the mass ratio of hollow silica, magnesium powder, sodium chloride and potassium chloride is 1:0.8:5:5.

In the specific operation of S3, the grinding time is not specified, and the mixing can be uniform.

In the specific operation of S3, the magnesium thermal reduction reaction is carried out in an argon atmosphere.

In the specific operation of S3, the temperature of the magnesium thermal reduction reaction is 700°C.

In the specific operation of S3, the heating rate was 3°C/min.

In the specific operation of S3, the holding time is 2.5h.

In the specific operation of S4, the concentration of hydrochloric acid is 1 mol/L.

In the specific operation of S4, the cleaning time of hydrochloric acid is 12h.

In the specific operation of S4, the concentration of hydrofluoric acid is 5wt%.

In the specific operation of S4, the cleaning time of hydrofluoric acid is 1h.

In the specific operation of S4, the drying method is vacuum drying.

In the specific operation of S4, the drying time is 12h.

The particle size of the hollow silicon microspheres obtained in S4 is about 450 nm.

Implementation Case 3

A preparation method of hollow nano-silicon ball, comprising the following steps

S1: Cetylamine bromide, sodium lauryl sulfate, ammonia water, absolute ethanol, and ultrapure water are mixed, and tetraethyl orthosilicate is added to carry out a sol-gel reaction to obtain a white powder.

S2: After the white powder was incubated, it was washed with acidic anhydrous ethanol and dried to obtain hollow silica after calcination.

S3: fully grind the hollow silica with magnesium powder, sodium chloride, potassium chloride, etc., mix, and calcine to obtain a brown mixture.

S4: After the brown mixture is washed with hydrochloric acid and hydrofluoric acid and dried, hollow nano-silicon spheres are obtained.

Wherein, the specific operation of S1 is: dissolving cetyl ammonium bromide and sodium dodecyl sulfate in a mixed solution of ultrapure water and absolute ethanol, adding ammonia water, and stirring. Tetraethyl orthosilicate is added dropwise to the mixed solution, stirred and filtered to obtain a white powder. The obtained white powder is incubated, washed, dried and calcined to obtain hollow silica.

In the specific operation of S1, the reaction temperature was 35°C.

In the specific operation of S1, the stirring rate was 800 rpm.

In the specific operation of S1, the reaction time is 20h.

In the specific operation of S1, the mass-volume (g/L) ratio of cetylammonium bromide, sodium dodecyl sulfate and water is 1.5:1.5:1.

In the specific operation of S1, the volume ratio of ammonia water, tetraethyl orthosilicate, absolute ethanol, and water is: 1:1:25:35.

In the specific operation of S1, the concentration of ammonia water is 28wt%.

In the specific operation of S2, the white powder was incubated in ultrapure water.

In the specific operation of S2, the incubation temperature was 80°C.

In the specific operation of S2, the incubation time was 48h.

In the specific operation of S2, wash in absolute ethanol, and add 0.3 ml of hydrochloric acid.

In the specific operation of S2, the cleaning temperature was 65°C.

In the specific operation of S2, the cleaning time is 12h.

In the specific operation of S2, the drying temperature is 80°C and the drying time is 12h.

In the specific operation of S2, calcination is carried out in air.

In the specific operation of S2, the calcination temperature is 550°C.

In the specific operation of S2, the calcination time is 6h.

The particle size of the hollow silica obtained in S2 was 450 nm.

In the specific operation of S3, the mass ratio of hollow silica, magnesium powder, sodium chloride and potassium chloride is 1:1:10:10.

In the specific operation of S3, the grinding time is not specified, and the mixing can be uniform.

In the specific operation of S3, the magnesium thermal reduction reaction is carried out in an argon atmosphere.

In the specific operation of S3, the temperature of the magnesium thermal reduction reaction is 700°C.

In the specific operation of S3, the heating rate was 5°C/min.

In the specific operation of S3, the holding time is 3h.

In the specific operation of S4, the concentration of hydrochloric acid is 2 mol/L.

In the specific operation of S4, the cleaning time of hydrochloric acid is 6h.

In the specific operation of S4, the concentration of hydrofluoric acid is 10wt%.

In the specific operation of S4, the cleaning time of hydrofluoric acid is 0.5h.

In the specific operation of S4, the drying method is vacuum drying.

In the specific operation of S4, the drying time is 12h.

The particle size of the hollow silicon microspheres obtained in S4 is about 500 nm.

Fig. 1 is a TEM image of the hollow silica of Example 3, Fig. 2 is a TEM image of the hollow nano-silicon spheres of Example 3, Fig. 3 is the charge-discharge performance of the hollow nano-silicon spheres of The test results of the cycle performance show that at a current density of 1.0A/g, the hollow nano-silicon spheres still have a capacity of 1200mAh/g after 100 cycles, which is much higher than that of ordinary silicon (only 400mAh/g remains after 100 cycles. ).

The above are all preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited to this, and changes or replacements according to the concept of the present invention should be covered within the protection scope of the present invention.

Claims (7)

1. a preparation method of hollow nano-silicon sphere negative electrode material, it is characterized in that, prepare hollow silica by sol-gel method, and carry out magnesium thermal reduction to it to obtain hollow nano-silicon sphere. 2. preparation method according to claim 1, is characterized in that, described preparation method specifically comprises the following steps: S1: mix cetyl amine bromide, sodium lauryl sulfate, ammonia water, dehydrated alcohol and water and add tetraethyl orthosilicate to carry out sol-gel reaction to obtain white powder; S2: after incubating the obtained white powder in water, washing and drying with acidic absolute ethanol, and calcining to obtain hollow silica; S3: fully grind the hollow silica with magnesium powder, sodium chloride, potassium chloride, etc., mix, and calcine to obtain a brown mixture; S4: After the brown mixture is washed with hydrochloric acid and hydrofluoric acid and dried, hollow nano-silicon spheres are obtained. 3. preparation method according to claim 2 is characterized in that, the concrete operation of S1 is: cetyl ammonium bromide and sodium lauryl sulfate are dissolved in the mixed solution of ultrapure water and absolute ethanol , add ammonia water, stir, add tetraethyl orthosilicate dropwise to the mixed solution, stir, and obtain white powder after suction filtration; in the specific operation of S1, the reaction temperature is 30-35 ℃, and the stirring rate is 500- 800rpm, the reaction time is 20-30h, the mass-volume (g/L) ratio of cetyl ammonium bromide, sodium dodecyl sulfate and water is 1.5-3.5: 1.5-3.5: 0.5-2, ammonia water, normal The volume ratio of tetraethyl silicate, absolute ethanol and water is: 0.5-1.5:0.5-1.2:25-40:35-60, and the concentration of ammonia water is 28wt%. 4. The preparation method according to claim 2, characterized in that, in the specific operation of S2, the white powder is incubated in ultrapure water, the incubation temperature is 65-90°C, and the incubation time is 24h-72h. Wash in ethanol, and add 0.2-0.5ml of hydrochloric acid, the cleaning temperature is 60-70 °C, and the cleaning time is 6-12 hours; the drying temperature is 80 °C, and the drying time is 12 hours; calcined in the air, the calcination temperature is 450-600 °C, and the calcination time is 4 -8h. 5. preparation method according to claim 2 is characterized in that, in the concrete operation of S3, the mass ratio of hollow silica, magnesium powder, sodium chloride and potassium chloride is 1:0.8-1.5:5-10 : 5-10; the grinding time is not specified, just mix well; the magnesium thermal reduction reaction is carried out in an argon atmosphere, the magnesium thermal reduction reaction temperature is 650 ℃-700 ℃, and the heating rate is 1-10 ℃/min , the holding time is 2.5-4h. 6. preparation method according to claim 2 is characterized in that, in the concrete operation of S4, hydrochloric acid concentration is 1-3mol/L, and the cleaning time of hydrochloric acid is 5-12h; The concentration of hydrofluoric acid is 5-10wt% , the cleaning time of hydrofluoric acid is 1-3h; the drying method is vacuum drying, and the drying time is 12-24h. 7. Application of the hollow nano-silicon spheres prepared by the preparation method according to any one of claims 1 to 6 in negative electrode materials for lithium ion batteries.