阅读说明：本技术 一种硅氧复合材料及其制备方法 (Silica composite material and preparation method thereof ) 是由 席利华 赵艳雁 张君平 于 2020-04-27 设计创作，主要内容包括：本公开提供了一种硅氧复合材料,该复合材料包括线状多孔骨架和沉积在所述线状多孔骨架孔隙中的硅氧纳米颗粒；所述线状多孔骨架孔径为5-10nm,孔隙率为20-35％,所述硅氧纳米颗粒的粒径为5-8nm；优选地,所述线状多孔骨架孔径为6-8nm,孔隙率为25-30％；所述硅氧纳米颗粒的粒径为5-6nm。该复合材料可以作为负极材料进一步缓解充放电过程中体积膨胀产生的应力,提升硅负极材料的导电性和机械强度。(The present disclosure provides a silicon-oxygen composite material comprising a linear porous skeleton and silicon-oxygen nanoparticles deposited in pores of the linear porous skeleton; the aperture of the linear porous skeleton is 5-10nm, the porosity is 20-35%, and the particle size of the silica nano-particles is 5-8 nm; preferably, the pore diameter of the linear porous skeleton is 6-8nm, and the porosity is 25-30%; the particle size of the silica nano-particles is 5-6 nm. The composite material can be used as a negative electrode material to further relieve stress generated by volume expansion in the charge-discharge process, and the conductivity and mechanical strength of the silicon negative electrode material are improved.)

1. A silicon-oxygen composite material, characterized in that the silicon-oxygen composite material comprises a linear porous skeleton and silicon-oxygen nanoparticles deposited in pores of the linear porous skeleton;

the aperture of the linear porous skeleton is 5-10nm, and the porosity is 20-35%; the grain diameter of the silica nano-particles is 5-8 nm; preferably, the pore diameter of the linear porous skeleton is 6-8nm, and the porosity is 25-30%; the particle size of the silica nano-particles is 5-6 nm.

2. The silicone composite of claim 1Wherein the linear porous skeleton is made of at least one of multi-wall carbon nanotubes, carbon nanofibers and transition metal oxide nanorods; the transition metal oxide nanorod is Fe₃O₄Nanorods or Co₃O₄And (4) nanorods.

3. The silicone composite material according to claim 1, wherein the silicone composite material comprises a conductive layer wrapped around the surface of the linear porous skeleton; the thickness of the conducting layer is 50-100 nm; preferably 50-70 nm;

preferably, the first and second electrodes are formed of a metal,

the conductive layer is an amorphous carbon conductive layer;

or, preferably, the number of bits in the bit stream,

the conducting layer is made of conducting polymers, and the conducting polymers are at least one of polydopamine, polyaniline, polypyrrole, polypyridine and polydivinylthiophene.

4. A process for preparing the silicone composite material according to any one of claims 1 to 3, characterized in that it comprises the following steps:

s1, adding the mixture into the first alkaline solution, mixing the mixture with the precursor of the linear porous framework, drying the mixture, and then carrying out first calcination to obtain the linear porous framework;

s2, dispersing the linear porous skeleton in water to obtain a dispersion liquid, then uniformly mixing the dispersion liquid and a silicon source material, and carrying out hydrolysis treatment on the silicon source material to obtain a material after hydrolysis treatment;

s3, filtering the hydrolyzed material to obtain filter residue, and carrying out secondary calcination on the filter residue in a reducing atmosphere.

5. The method of claim 4, wherein the wire-like porous scaffolding precursor is multi-walled carbon nanotubes, carbon nanofibers, and transition metal oxide nanorods; preferably, the transition metal oxide nanorod is Fe₃O₄Nanorods or Co₃O₄A nanorod; what is needed isThe silicon source material is silicate ester, and preferably the silicate ester is methyl orthosilicate, ethyl orthosilicate and propyl orthosilicate; the first alkaline solution is an alcoholic solution of alkali metal hydroxide, preferably the alcoholic solution of alkali metal hydroxide is a potassium hydroxide ethanol solution and/or a sodium hydroxide ethanol solution; the concentration of the alkali metal hydroxide in the first alkaline solution is 0.1-0.2 g/mL; performing the hydrolysis treatment by adding a second alkaline solution, preferably the second alkaline solution is ammonia; the reducing atmosphere is hydrogen-argon mixed gas.

6. The method of claim 4, wherein in step S1, the conditions of the first calcining include: the first calcination is carried out in inert gas, the temperature rise rate of the first calcination is 2-5 ℃/min, the calcination temperature of the first calcination is 600-800 ℃, and the calcination time of the first calcination is 1.5-3 h;

in step S2, the conditions of the second calcination include: calcining at the temperature of 700 ℃ and 800 ℃ for 1-2h, wherein the hydrolysis conditions comprise: the hydrolysis temperature is 30-40 ℃, and the hydrolysis time is 12-18 h; the dispersion is ultrasonic dispersion, the water for dispersion is distilled water and/or deionized water, and the conditions of the ultrasonic dispersion comprise: the frequency of the ultrasonic dispersion is 20-40kHz, the specific power of the ultrasonic dispersion is 400-800W/L, and the ultrasonic dispersion time is 15-25 min;

in step S3, the conditions of the second calcination include: the temperature of the second calcination is 700-800 ℃, and the time of the second calcination is 1-2 h.

7. The method of any of claims 4-6, wherein the method further comprises: mixing the product obtained by the second calcination with water, a conductive polymer monomer and an oxidant, carrying out in-situ polymerization on a conductive polymer to obtain a product A, filtering and washing the product A in a weak acid solution to be neutral, and then carrying out drying treatment; the conductive polymer monomer is at least one selected from pyrrole, aniline and dopamine, and the weak acid solution is an HF solution;

preferably, the first and second electrodes are formed of a metal,the oxidant is selected from FeCl₃、H₂O₂And ammonium persulfate; the conditions for the in situ polymerization of the conductive polymer include: at the temperature of minus 5 ℃ to minus 5 ℃, the mixture is stirred magnetically for 10 to 20 hours at a constant speed of 500 plus one minute and 600 r/min.

8. The method of claim 7, wherein the method further comprises: performing third calcination on the dried product in reducing gas; the conditions of the third calcination include: calcining at the temperature of 700 ℃ and 800 ℃ for 1-2 h; the reducing atmosphere is hydrogen-argon mixed gas.

9. A negative electrode comprising a current collector and a negative electrode material coated on the current collector, wherein the negative electrode material is the silicon-oxygen composite material of any one of claims 1 to 3 and the silicon-oxygen composite material prepared by the method of any one of claims 4 to 8.

10. A lithium battery, which comprises a positive electrode and a negative electrode, wherein the negative electrode comprises a current collector and a negative electrode material coated on the current collector, and is characterized in that the negative electrode material is the silicon-oxygen composite material disclosed in any one of claims 1 to 3 and the silicon-oxygen composite material prepared by the method disclosed in any one of claims 4 to 8.

Technical Field

The application relates to the technical field of lithium ion batteries, in particular to a silica composite material and a preparation method thereof.

Background

With the rapid development of the electric automobile industry, the requirements on the energy density, the cycle life, the safety performance and the like of the matched power battery of the electric automobile are continuously improved. At present, most of negative electrode materials of lithium ion power batteries produced in mass production in the market mainly comprise graphite, the rate performance of the graphite negative electrode materials is poor, side reactions are more, the stability of a laminated structure is to be improved, and the market demand is difficult to meet. The silicon negative electrode material has the advantages of high theoretical capacity (4200mAh/g), low lithium intercalation/deintercalation platform, abundant resources, good safety and the like as a novel negative electrode material with the most potential, so the silicon negative electrode material becomes a main research direction of the negative electrode material of the lithium ion power battery.

However, during the charging and discharging process, the silicon negative electrode material is accompanied by huge volume change (the volume change is as high as 300%), so that the electrode material is pulverized and loses electric contact, the SEI film is continuously broken and repaired, and the capacity is rapidly attenuated. The theoretical capacity of the silicon oxide (2600mAh/g) is lower than that of silicon, the strength of Si-O bond is 2 times that of Si-Si bond, and Li generated during the first week reaction₂O、Li₄SiO₄The silicon dioxide is separated out by a skeleton network and serves as a good in-situ buffer matrix, and although the volume effect of active metal silicon particles in the charging and discharging process is inhibited to a certain extent, the problems caused by volume change cannot be completely eliminated, and the cycle stability of the silicon dioxide is still to be improved. In addition, in the first circulation process, due to the generation of inert components in the silicon monoxide, larger irreversible capacity is brought, and the first coulombic efficiency is low. These factors greatly limit the performance of the silica electrochemistry and its practical application.

Therefore, a suitable silicon negative electrode material needs to be found, which not only can effectively improve the cycling stability in the charging and discharging process, but also can improve the first coulomb efficiency in the first cycling process.

Disclosure of Invention

The purpose of the present disclosure is to provide a silicon-oxygen composite material to relieve stress generated by volume expansion during charging and discharging, and further improve conductivity and mechanical strength of a silicon negative electrode material.

In order to achieve the above object, the present disclosure provides, in one aspect, a silicon oxygen composite material including a linear porous skeleton and silicon oxygen nanoparticles deposited in pores of the linear porous skeleton; the aperture of the linear porous skeleton is 5-10nm, and the porosity is 20-35%; the grain diameter of the silica nano-particles is 5-8 nm; preferably, the pore diameter of the linear porous skeleton is 6-8nm, and the porosity is 25-30%; the particle size of the silica nano-particles is 5-6 nm.

Optionally, the material of the linear porous skeleton is at least one of multi-wall carbon nanotubes, carbon nanofibers and transition metal oxide nanorods; the transition metal oxide nanorod is Fe₃O₄Nanorods or Co₃O₄And (4) nanorods.

Optionally, the composite material comprises a conductive layer wrapped on the surface of the linear porous skeleton; the thickness of the conducting layer is 50-100 nm; preferably 50-70 nm.

Optionally, the conductive layer is an amorphous carbon conductive layer.

Optionally, the material of the conductive layer is a conductive polymer, and the conductive polymer is at least one of polydopamine, polyaniline, polypyrrole, polypyridine, and polydivinylthiophene.

In another aspect, the present disclosure provides a method of preparing a silicone composite material, the method comprising the steps of:

s1, adding the mixture into the first alkaline solution, mixing the mixture with the precursor of the linear porous framework, drying the mixture, and then carrying out first calcination to obtain the linear porous framework;

s2, dispersing the linear porous skeleton in water to obtain dispersion liquid, then uniformly mixing silicon source materials of the dispersion liquid, and carrying out hydrolysis treatment on the silicon source materials to obtain a material after hydrolysis treatment;

s3, filtering the hydrolyzed material to obtain filter residue, and carrying out secondary calcination on the filter residue in a reducing atmosphere.

Optionally, the linear porous skeleton precursor is a multi-walled carbon nanotube, a carbon nanofiber and a transition metal oxide nanorod; preferably, the transition metal oxide nanorod is a Fe3O4 nanorod or a Co3O4 nanorod; the silicon source material is silicate ester, and preferably the silicate ester is methyl orthosilicate, ethyl orthosilicate and propyl orthosilicate; the first alkaline solution is an alcoholic solution of alkali metal hydroxide, preferably the alcoholic solution of alkali metal hydroxide is a potassium hydroxide ethanol solution and/or a sodium hydroxide ethanol solution; the concentration of the alkali metal hydroxide in the first alkaline solution is 0.1-0.2 g/mL; performing the hydrolysis treatment by adding a second alkaline solution, preferably the second alkaline solution is ammonia; the reducing atmosphere is hydrogen-argon mixed gas.

Alternatively, in step S1, the conditions of the first calcination include: the first calcination is carried out in inert gas, the temperature rise rate of the first calcination is 2-5 ℃/min, the calcination temperature of the first calcination is 600-800 ℃, and the calcination time of the first calcination is 1.5-3 h;

in step S2, the conditions of the second calcination include: calcining at the temperature of 700 ℃ and 800 ℃ for 1-2h, wherein the hydrolysis conditions comprise: the hydrolysis temperature is 30-40 ℃, and the hydrolysis time is 12-18 h; the dispersion is ultrasonic dispersion, the water for dispersion is distilled water and/or deionized water, and the conditions of the ultrasonic dispersion comprise: the frequency of the ultrasonic dispersion is 20-40kHz, the specific power of the ultrasonic dispersion is 400-800W/L, and the ultrasonic dispersion time is 15-25 min;

in step S3, the conditions of the second calcination include: the temperature of the second calcination is 700-800 ℃, and the time of the second calcination is 1-2 h.

Optionally, the method further comprises: mixing the product obtained by the second calcination with water, a conductive polymer monomer and an oxidant, carrying out in-situ polymerization on the conductive polymer, magnetically stirring under the action of the oxidant to obtain a product A, filtering and washing the product A in a weak acid solution to be neutral, and then drying; the conductive polymer monomer is at least one selected from pyrrole, aniline and dopamine, and the weak acid solution is an HF solution.

Optionally, the oxidizing agentSelected from FeCl₃、H₂O₂And ammonium persulfate; the conditions for the in situ polymerization of the conductive polymer include: in ice bath, under the temperature of minus 5 ℃ to minus 5 ℃, the mixture is stirred for 10 to 20 hours by magnetic force at a constant speed of 500 plus one minute and 600 r/min.

Optionally, the method further comprises: performing third calcination on the dried product in reducing gas; the conditions of the third calcination include: calcining at the temperature of 700 ℃ and 800 ℃ for 1-2 h; the reducing atmosphere is hydrogen-argon mixed gas.

In yet another aspect, the present disclosure provides a negative electrode.

In yet another aspect, the present disclosure provides a lithium battery.

Through the technical scheme, the silicon-oxygen composite material is of a one-dimensional linear structure, is good in conductivity and small in expansion, the size of silicon oxide is limited by the porous framework, and the porous framework can be used as a buffer matrix to relieve stress generated by volume expansion in the lithium desorption and insertion process.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Detailed Description

The following describes in detail specific embodiments of the present disclosure. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

One aspect of the present disclosure provides a silicon oxygen composite material comprising a linear porous skeleton and silicon oxygen nanoparticles deposited in pores of the linear porous skeleton; the aperture of the linear porous skeleton is 5-10nm, and the porosity is 20-35%; the grain diameter of the silica nano-particles is 5-8 nm; preferably, the pore diameter is 6-8nm, the porosity is 25-30%, and the particle size is 5-6 nm.

The silicon-oxygen composite material provided by the disclosure has a one-dimensional linear structure as a whole, is good in conductivity and small in expansion, and the porous framework not only limits the size of silicon oxide, but also can be used as a buffer matrix to relieve stress generated by volume expansion in the lithium releasing and embedding process. In addition, the particle size of the silica nano particles is further limited by limiting the pore structure of the one-dimensional porous framework, and the volume expansion in the charging and discharging process can be effectively relieved by the porous structure of the one-dimensional porous framework and the conductive polymer coating layer coated on the surface of the one-dimensional porous framework.

Preferably, the material of the linear porous skeleton is at least one of multi-wall carbon nanotubes, carbon nanofibers and transition metal oxide nanorods; the transition metal oxide nanorod is Fe₃O₄Nanorods or Co₃O₄And (4) nanorods.

According to the present disclosure, the composite material comprises a conductive layer wrapped on the surface of the one-dimensional porous skeleton; the thickness of the conducting layer is 50-100 nm; preferably 50-70 nm. The conductive layer further improves the conductivity and mechanical strength of the material, so that direct contact between silicon oxide nanoparticles and electrolyte is blocked, and the generated SEI film is more stable.

According to the present disclosure, the conductive layer is preferably an amorphous carbon conductive layer, so that the conductivity of the material is further improved, the contact area of the silica nanoparticles and the electrolyte is improved, and the generation of side reactions is reduced.

Preferably, the conductive layer is made of a conductive polymer with good conductivity, and the conductive polymer is at least one of polydopamine, polyaniline, polypyrrole, polypyridine and polydivinylthiophene.

In another aspect, the present disclosure provides a method of preparing a silicone composite material, the method comprising the steps of:

s1, adding the mixture into the first alkaline solution, mixing the mixture with the precursor of the linear porous framework, drying the mixture, and then carrying out first calcination to obtain the linear porous framework;

s2, dispersing the linear porous skeleton in water to obtain dispersion liquid, then uniformly mixing silicon source materials of the dispersion liquid, and carrying out hydrolysis treatment on the silicon source materials to obtain a material after hydrolysis treatment;

s3, filtering the hydrolyzed material to obtain filter residue, and carrying out secondary calcination on the filter residue in a reducing atmosphere.

According to the method, a linear porous framework precursor is selected as a basic framework, a first alkaline solution is added, and reaction and pore-forming are carried out under a high-temperature inert atmosphere to prepare a linear porous framework; adding a silicon source, hydrolyzing, and generating silicon oxide in situ in the linear porous skeleton; and (2) calcining the silicon-oxygen composite material at high temperature under a reducing atmosphere to obtain the silicon-oxygen composite material comprising a linear porous skeleton and silicon-oxygen nano particles deposited in pores of the linear porous skeleton. The method disclosed by the invention has the advantages that the specific reaction conditions of the steps are adjusted, so that the obtained silicon-oxygen composite material has the pore diameter and porosity of a linear framework in a proper range and the particle size of deposited silicon-oxygen particles, and thus, an ideal silicon-oxygen composite material is obtained.

According to the present disclosure, the linear porous scaffold precursor is a multiwalled carbon nanotube, a carbon nanofiber and a nanorod; preferably, the transition metal oxide nanorods; the transition metal oxide nanoparticles are Fe₃O₄Nanorods or Co₃O₄A nanorod; the silicon source material is silicate ester, and preferably the silicate ester is methyl orthosilicate, ethyl orthosilicate and propyl orthosilicate; the first alkaline solution is an alcoholic solution of alkali metal hydroxide, preferably the alcoholic solution of alkali metal hydroxide is a potassium hydroxide ethanol solution and/or a sodium hydroxide ethanol solution; the concentration of the alkali metal hydroxide in the first alkaline solution is 0.1-0.2 g/mL; performing the hydrolysis treatment by adding a second alkaline solution, preferably the second alkaline solution is ammonia water, wherein the percentage content of the ammonia water can be 25-28%; the weak acid solution is HF solution; the reducing atmosphere is hydrogen-argon mixed gas, wherein the hydrogen-argon ratio in the hydrogen-argon mixed gas can be 1: 9-19.

The present disclosure may control the relative mass ratio of the linear porous framework in the silicon-oxygen composite material to the silicon-oxygen nanoparticles deposited in the pores of the linear porous framework by controlling the amounts of the linear porous framework precursor and the silicon source material. In the present disclosure, the amount of the first basic solution may be 15 to 30mL with respect to 1g of the linear porous skeleton precursor; the amount of water used for dispersion may be 80 to 120mL, and the amount of the silicon source material may be 8 to 15mL, relative to 1g of the linear porous skeleton.

According to the present disclosure, in step S1, the conditions of the first calcination include: the first calcination is carried out in inert gas, the temperature rise rate of the first calcination is 2-5 ℃/min, the calcination temperature of the first calcination is 600-800 ℃, and the calcination time of the first calcination is 1.5-3 h; in step S2, the conditions of the second calcination include: calcining at the temperature of 700 ℃ and 800 ℃ for 1-2h, wherein the hydrolysis conditions comprise: the hydrolysis temperature is 30-40 ℃, and the hydrolysis time is 12-18 h; the dispersion is ultrasonic dispersion, the water for dispersion is distilled water and/or deionized water, and the conditions of the ultrasonic dispersion comprise: the frequency of the ultrasonic dispersion is 20-40kHz, the specific power of the ultrasonic dispersion is 400-800W/L, and the ultrasonic dispersion time is 15-25 min; in step S3, the conditions of the second calcination include: the temperature of the second calcination is 700-800 ℃, and the time of the second calcination is 1-2 h.

According to the present disclosure, the method of preparing a silicone composite material may further comprise: mixing the product obtained by the second calcination with water, a conductive polymer monomer and an oxidant, carrying out in-situ polymerization on the conductive polymer to obtain a product A, filtering and washing the product A in a weak acid solution to be neutral, and then carrying out drying treatment; the conductive polymer monomer is at least one selected from pyrrole, aniline and dopamine, and the weak acid solution is an HF solution. According to the method, pyrrole, aniline or dopamine is added after a product obtained by second calcination is dispersed in deionized water, so that the silicon-oxygen composite material is provided with a conductive polymer coating layer coated on the surface of the one-dimensional porous skeleton, the conductivity and mechanical strength of the material are further improved, direct contact between silicon-oxygen nano particles and electrolyte is blocked, and a generated SEI film is more stable.

Preferably, the oxidizing agent is selected from FeCl₃、H₂O₂And ammonium persulfate; the conditions for the in situ polymerization of the conductive polymer include: at the temperature of minus 5 ℃ to minus 5 ℃, the mixture is stirred magnetically for 10 to 20 hours at a constant speed of 500 plus one minute and 600 r/min.

Further preferably, the method for preparing the silicone composite material may further comprise: performing third calcination on the dried product in reducing gas; the conditions of the third calcination include: calcining at the temperature of 700 ℃ and 800 ℃ for 1-2 h; the reducing atmosphere is hydrogen-argon mixed gas, wherein the hydrogen-argon ratio in the hydrogen-argon mixed gas can be 1: 9-19. The method comprises the step of subjecting a silicon-oxygen composite material with a conductive polymer coating layer coated on the surface of a one-dimensional porous framework to third calcination in reducing gas to further carbonize the conductive polymer coating layer, so as to obtain an amorphous carbon coating layer.

In yet another aspect, the present disclosure provides a negative electrode comprising a current collector and a negative electrode material coated on the current collector, wherein the negative electrode material is the silica composite of the present disclosure. By using the silicon-oxygen composite material as the silicon cathode material, the stress generated by volume expansion of the existing silicon cathode material in the charging and discharging process is relieved, so that the conductivity and the mechanical strength of the silicon cathode material are further improved.

In yet another aspect, the present disclosure provides a lithium battery including a positive electrode and a negative electrode, the negative electrode including a current collector and a negative electrode material coated on the current collector, the negative electrode material being the silica composite of the present disclosure.

The present disclosure is further illustrated by the following examples, but is not to be construed as being limited thereby.

The materials, reagents, instruments and equipment used in the examples of the present disclosure are commercially available, unless otherwise specified, wherein the carbon nanofibers are available from Sigma-

Example 1

Dissolving 3g of potassium hydroxide in 20ml of ethanol solution, adding 1g of carbon nanofiber, uniformly mixing, drying in a 180 ℃ forced air drying oven, and performing primary calcination on the dried product to obtain the linear porous framework. Wherein the conditions of the first calcination are as follows: heating to 800 ℃ at the heating rate of 5 ℃/min and calcining for 2 h.

And (3) washing 0.5g of linear porous skeleton deionized water to be neutral, performing ultrasonic dispersion in the deionized water, adding 5ml of ethyl orthosilicate, stirring for 30min, adding 5ml of 25% ammonia water, hydrolyzing at the constant temperature of 35 ℃ for 14h, filtering and washing a hydrolyzed product, and performing secondary calcination to obtain the silica composite material. Wherein the ultrasonic dispersion conditions are as follows: the frequency is 30kHz, the specific power of ultrasonic dispersion is 600W/L, and the ultrasonic dispersion time is 20 min; the conditions of the second calcination are: calcining at the high temperature of 730 ℃ for 1.5h in a hydrogen-argon mixed gas, wherein the hydrogen-argon ratio in the hydrogen-argon mixed gas is 1: 19.

example 2

Dissolving 3g of potassium hydroxide in 20ml of ethanol solution, adding 1g of carbon nanofiber, uniformly mixing, drying in a 180 ℃ forced air drying oven, and performing primary calcination on the dried product to obtain the linear porous framework. Wherein the conditions of the first calcination are as follows: heating to 800 ℃ at the heating rate of 5 ℃/min and calcining for 2 h.

Washing 0.5g of linear porous skeleton deionized water to be neutral, then ultrasonically dispersing in the deionized water, adding 5ml of ethyl orthosilicate, stirring for 30min, then adding 5ml of 25 percent ammonia water, hydrolyzing for 14h at the constant temperature of 35 ℃, filtering and washing the hydrolyzed product, and then carrying out secondary calcination. Wherein the ultrasonic dispersion conditions are as follows: the frequency is 30kHz, the specific power of ultrasonic dispersion is 600W/L, and the ultrasonic dispersion time is 20 min; the conditions of the second calcination are: calcining at the high temperature of 730 ℃ for 1.5h in a hydrogen-argon mixed gas, wherein the hydrogen-argon ratio in the hydrogen-argon mixed gas is 1: 19.

dispersing the product obtained by the second calcination in 50ml of deionized water, adding 5g of dopamine monomer and 1g of ammonium persulfate, magnetically stirring for 12 hours at a constant speed in an ice bath at a stirring speed of 550r/min, filtering and washing to obtain a product A, adding the product A into 10ml of 5% HF solution, stirring for 10 minutes, filtering and washing to be neutral, and drying to obtain the silica composite material.

Example 3

This example prepares a silicone composite material according to the method of example 2. Except that the silica composite material prepared in example 2 was subjected to a third calcination. Wherein the third calcining condition is as follows: calcining at 800 deg.C for 1h in mixed gas of hydrogen and argon.

Example 4

This example prepares a silicone composite material according to the method of example 2. Except that the conditions of the first calcination in this example were: heating to 750 ℃ at the heating rate of 3 ℃/min and calcining for 2 h.

Example 5

This example prepares a silicone composite material according to the method of example 2. Except that the conditions of the first calcination in this example were: heating to 700 ℃ at the heating rate of 2 ℃/min and calcining for 2 h.

Example 6

This example prepares a silicone composite material according to the method of example 2. Except that the conditions of the second calcination in this example were: calcining at 700 deg.C for 1.5h in mixed gas of hydrogen and argon.

Example 7

This example prepares a silicone composite material according to the method of example 2. Except that the conditions of the second calcination in this example were: calcining at 800 deg.C for 3h in mixed gas of hydrogen and argon.

Example 8

This example prepares a silicone composite material according to the method of example 2. Except that the conditions of the first calcination in this example were: heating to 730 ℃ at the heating rate of 3 ℃/min and calcining for 2 h; the conditions of the second calcination are: calcining at 800 deg.C for 1h in mixed gas of hydrogen and argon.

Example 9

This example prepares a silicone composite material according to the method of example 2. The difference is that the product obtained by the second calcination is dispersed in 50ml of deionized water, 3g of pyrrole and 1g of oxidant ammonium persulfate are added, the mixture is magnetically stirred for 15h at a constant stirring speed of 550r/min in an ice bath, and the product A is obtained after filtration and washing.

Example 10

This example prepares a silicone composite material according to the method of example 2. Except that the product obtained by the second calcination was dispersed in 50ml of deionized waterIn (5 g) aniline and 5ml H are added₂O₂And magnetically stirring at a constant speed of 550r/min for 35 hours in an ice bath, and filtering and washing to obtain a product A.

Example 11

This example prepares a silicone composite material according to the method of example 2. Except that the carbon nanofibers were replaced with Fe₃O₄And (4) nanorods.

Comparative example 1

This comparative example a silicone composite was prepared according to the method of example 1. Except that the conditions for the first calcination in this comparative example were: heating to 850 ℃ at the heating rate of 10 ℃/min and calcining for 1 h.

Comparative example 2

This comparative example a silicone composite was prepared according to the method of example 1. Except that the conditions for the second calcination in this comparative example were: calcining at 800 deg.C for 2h in mixed gas of hydrogen and argon.

Comparative example 3

This example prepares a silicone composite material according to the method of example 1. Except that the conditions for the first calcination in this comparative example were: heating to 900 ℃ at the heating rate of 15 ℃/min and calcining for 1 h; the conditions of the second calcination are: calcining at 1000 deg.C for 0.5h in hydrogen-argon mixture; wherein, the hydrogen-argon ratio in the hydrogen-argon mixed gas is 1: 19.

comparative example 4

Silicon oxygen anode material available from OTC corporation.

Test example 1

Pore diameters, porosities, particle diameters of silicone nano particles, and thicknesses of the conductive polymer coating layers of the linear porous frameworks of the silicone composite materials obtained in examples 1 to 11, comparative examples 1 to 3, and the commercially available silicone negative electrode material of comparative example 4 were measured, and the measurement results are shown in table 1.

Table 1:

group of	Pore size (nm)	Porosity (%)	Silica nanoparticle size (nm)	Thickness of coating (nm)
					Example 1	6-8	25％	5-6	/
Example 2	6-8	26％	5-6	65
					Example 3	6-8	28％	5-6	55
Example 4	8-10	20％	5-6	64
					Example 5	6-10	33％	5-7	65
Example 6	5-8	29％	7-8	63
					Example 7	6-9	27％	6-8	63
Example 8	5-10	32％	6-8	66
					Example 9	6-9	25％	5-7	70
Example 10	6-8	28％	5-6	60
					Example 11	7-10	28％	5-8	62
Comparative example 1	15-18	10％	12-15	/
					Comparative example 2	20-25	18％	22-25	/
Comparative example 3	20-30	17％	25-30	/
					Comparative example 4	/	/	Over 100nm	/

Test example 2

The silicon-oxygen composite materials prepared in examples 1 to 11 and comparative examples 1 to 3 and the silicon-oxygen negative electrode material commercially available in comparative example 4 are respectively used as a negative electrode active material, acetylene black and sodium carboxymethylcellulose according to the proportion of 8: 1: 1, uniformly mixing, and coating on a copper foil to obtain a working pole piece; using a metal lithium sheet as a counter electrode; the button cell is made by taking the PE/PP composite diaphragm as an ion exchange membrane and adopting a conventional method in the field.

Discharging the button cell to 0.005V at constant current of 0.5A at normal temperature, then charging to 1.5V at constant current of 0.5mA, circularly charging for 100 circles, recording the discharge capacity and the charge capacity of the cell, and calculating the first reversible capacity, the first coulombic efficiency and the residual capacity after charging for 100 circles of the cell, wherein the specific data are shown in Table 2.

The first coulombic efficiency calculation formula is as follows: first discharge capacity/first charge capacity 100%

Table 2:

group of	First reversible capacity mAh/g	First coulombic efficiency%	100 circles of residual capacity mAh/g
				Example 1	1716.99	68.6	910
Example 2	1822.8	75.3	1518.9
				Example 3	1795.185	78.6	1554.72
Example 4	1732.705	74.5	1368.2
				Example 5	1795.4	73.2	1294.4
Example 6	1781.25	75.4	1343.1
				Example 7	1736.25	70.6	1202
Example 8	1726.1	76.4	1099.21
				Example 9	1697.25	73.6	1156.5
Example 10	1659.85	75.1	1085
				Example 11	1641.45	72.6	1199.64
Comparative example 1	1655.05	68.9	856.23
				Comparative example 2	1662.95	66.45	788.915
Comparative example 3	1639.25	65.4	694.805
				Comparative example 4	1874.988	63.7	329.346

Test example 3

Working electrode sheets and button cells were made according to the method of test example 2. And measuring the original thickness of each group of sample pole pieces by using a micrometer before assembling the button cell. After the button cell is circulated for 50 circles, the cell is completely discharged, the button cell is disassembled, the negative plate is taken out, the cell is cleaned by DMC solution, the cell is dried, the thickness test is carried out, the expansion rate is calculated, and the specific data are shown in Table 3.

Wherein, the calculation formula of the expansion ratio is as follows: (T)₁₀₀-T₀)/T₀

Table 3:

the silicon-oxygen composite material disclosed by the invention is of a one-dimensional linear structure, good in conductivity and small in expansion, and the porous framework not only limits the size of silicon oxide, but also can be used as a buffer matrix for relieving stress generated by volume expansion in the lithium desorption process. From the data in tables 2-3, it can be seen that the button cell prepared by using the silicone-oxygen composite material of the present disclosure has higher first reversible capacity and first coulombic efficiency, and the residual capacity after charging for 100 cycles is higher; and after 50 cycles of charging, the cell expansion rate of the button cell prepared by using the silicon-oxygen composite material disclosed by the invention is greatly reduced. Therefore, the volume expansion in the charging and discharging process can be effectively relieved by using the silicon-oxygen composite material as a battery negative electrode material.

The preferred embodiments of the present disclosure have been described in detail above, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.