CN110364700B - Silica composite material, preparation method thereof and lithium ion battery - Google Patents
Silica composite material, preparation method thereof and lithium ion battery Download PDFInfo
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Abstract
The invention relates to the technical field of lithium ion battery silicon materials, and particularly provides a silica composite material, a preparation method thereof and a lithium ion battery. The silica composite material is a composite material with a core-shell structure, and the core layer material is porous SiOxParticles, wherein the shell material is poly tannic acid, and a conductive agent is embedded between the core layer material and the shell material and in the shell material; wherein x is more than 0 and less than 2. The silica material has good conductivity and good structural stability, and can effectively improve the structural stability and rate characteristic of a silicon-based negative electrode material when used as a negative electrode active material of a lithium ion battery.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery silicon materials, and particularly relates to a silica composite material, a preparation method thereof and a lithium ion battery.
Background
Lithium ion batteries have the advantages of large capacity, long cycle life, no memory effect and the like, and are widely applied to the fields of digital products, electric tools and the like. With the continuous progress of the technology, the development and application of the high energy density lithium ion battery gradually enter the visual field of people, and the search and development of the lithium ion battery material with higher energy density become the key direction of research of researchers. In the research process of high-energy-density lithium ion battery materials, silicon is the material with the highest specific capacity in all negative electrode materials discovered nowadays, the specific mass capacity of the silicon can reach 3579mAh/g, and is more than 10 times of the specific capacity (372mAh/g) of the current commercialized graphite-based negative electrode materials, so that the silicon has a very large application prospect. However, the large volume change of silicon and silicon oxide materials during charge and discharge causes the breakage and pulverization of particles, which causes the continuous breakage and generation of a solid electrolyte interface film (SEI film), thereby causing a rapid decrease in the life span of a battery. In order to solve the above problems of the silicon negative electrode material, the prior art improves the surface characteristics of silicon by means of nano-crystallization, composite formation, alloying, etc. of silicon particles. Wherein, the nano-crystallization is to change silicon particles into nano-wires, nano-tubes, porous silicon, hollow silicon, silicon films and the like so as to weaken stress change in circulation; the compounding is to compound silicon with amorphous carbon, carbon nanotubes, graphene, titanium dioxide and the like, so that the volume change in the charging and discharging process is relieved; alloying is to make silicon particles into FeSi, NiSi, etc. to form bond energy on the silicon surface to resist silicon volume change and destruction. However, these methods for modifying silicon materials still cannot completely solve the problems of particle breakage and pulverization of silicon and silicon-oxygen materials during charging and discharging, and even if the silicon and silicon-oxygen materials are treated by the methods, the requirements of high-rate charging and discharging cannot be met.
Disclosure of Invention
Aiming at the problems that particles are broken and pulverized due to large volume change in the charging and discharging processes when the conventional silicon negative electrode material is used on a lithium ion battery, so that the stability of an SEI (solid electrolyte interphase) film is not facilitated, high-rate charging and discharging are not facilitated, the cycle life of the battery is short, and the like, the invention provides a silicon-oxygen composite material and a preparation method thereof.
Furthermore, the invention also provides a lithium ion battery taking the silicon-oxygen composite material as a negative active material.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the silica composite material is a composite material with a core-shell structure, and the core layer material is porous SiOxParticles, wherein the shell material is poly tannic acid, and a conductive agent is embedded between the core layer material and the shell material and in the shell material;
wherein x is more than 0 and less than 2.
Correspondingly, the preparation method of the silicon-oxygen composite material comprises the following steps:
step S01, SiOxDissolving the material in an alkaline solution, uniformly mixing, and heating to 30-70 ℃ to enable SiO to be dissolvedxReacting the material with an alkaline solution, separating, washing and drying to obtain an intermediate product;
s02, mixing the intermediate product with tannic acid, a conductive agent and deionized water, and performing ultrasonic treatment to obtain a uniform mixed solution;
and S03, adjusting the pH value of the mixed solution to be alkaline, so that the tannic acid is polymerized to obtain the silicon-oxygen composite material.
Further, the lithium ion battery comprises a negative electrode, wherein an active material on the negative electrode is selected from the silicon-oxygen composite material; or the active material of the negative electrode is prepared by the preparation method of the silicon-oxygen composite material.
The invention has the technical effects that:
compared with the prior art, the silicon-oxygen composite material provided by the invention is prepared from porous SiOxCoating a layer of polytannic acid on the surface of the particles to form a composite material with a core-shell structure, and coating polytannic acid and porous SiOxConductive agents are embedded among the particles and among the polytannic acid layers, so that the silica material has good conductivity and good structural stability, and when the silica material is used as a lithium ion battery cathode active material, the structural stability and the rate characteristic of the silicon-based cathode material can be effectively improved.
The preparation method of the silica composite material has simple preparation process, cheap and easily obtained raw materials, and porous SiOxForming polytannic acid on the surface of the particles as an artificial SEI film, and forming a poly-tannic acid film on the artificial SEI film and SiOxThe conductive agent is inserted between the particles, so that the silicon-oxygen composite material has good structural stability and good conductive property, and when the obtained silicon-oxygen composite material is used as a negative electrode active substance of a lithium ion battery, the high-rate charge and discharge performance of the battery can be improved.
According to the lithium ion battery, the silicon-oxygen composite material with the core-shell structure is adopted as the negative electrode active substance, and the silicon-oxygen composite material has excellent structural stability and excellent conductivity, so that the lithium ion battery is endowed with good high-rate charge-discharge characteristics and cycle life.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a diagram of SiO in example 1 of the present inventionxSEM image of intermediate product obtained after the particles are etched by alkali solution;
FIG. 2 is an SEM image of a silicon-oxygen composite material prepared in example 1 of the present invention;
FIG. 3 is an SEM and EDS chart of a silicon-oxygen composite material prepared by the preparation method of the silicon-oxygen composite material of the embodiment 2 of the invention and the mass ratio of O/Si before and after reaction;
fig. 4 is a cycle curve of a lithium ion battery made of a silicone-oxygen composite material prepared by the method for preparing a silicone-oxygen composite material of example 1 of the present invention;
FIG. 5 is a graph showing the cycle curves of lithium ion batteries made from the materials of example 2 of the present invention and comparative examples 1 and 2;
FIG. 6 is a graph showing the cycle curves of lithium ion batteries made of the materials of example 2 and comparative examples 1 and 2 of the present invention at different rates.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In one aspect of the present invention, a silicone composite material is provided. The silica composite material is a composite material with a core-shell structure, and the core layer material is porous SiOxThe particle, the shell material is poly tannic acid, and inlay the conductive agent between shell material and the material of nuclear layer, the inside of shell material is imbedded with the conductive agent at the same time; alternatively, the silicon oxygen composite material of the present invention comprises porous SiOxParticles and coated on porous SiOxPoly-tannic acid on the surface of the particles, and poly-tannic acid and porous SiOxConductive agents are embedded among the particles and in the poly-tannic acid layer, wherein x is more than 0 and less than 2.
Preferably, the conductive agent is at least one selected from carbon black, carbon nanotubes, graphene and other conductive agents. The carbon black includes acetylene black, ketjen black, conductive carbon black (Sp), and the like.
The size of the conductive agent is not more than 50nm, wherein the particle size of the carbon black is not more than 50 nm; the diameter of the carbon nano tube is less than or equal to 50 nm; the number of the graphene layers is less than or equal to 6 and the size of the graphene layers is not more than 50nm, if the size of the conductive agent is too large, the conductivity becomes better, but the large size brings gaps when being superposed, so that porous SiO in the silicon-oxygen composite material is causedxThe particles can not be isolated from the outside, and the artificial SEI film formed by the poly-tannic acid can not completely cover the porous SiOxParticles, when assembled into a lithium ion battery, electrolyte can enter the interior of the silicon-oxygen composite material along the gaps so as to be mixed with the porous SiOxParticle contact can reduce the structural stability of the silicone composite.
As a preferred silicon-oxygen composite material, porous SiO is used according to the mass ratioxAnd (3) particle: poly tannic acid: a conductive agent (10-50): (0.5-2): (0.5-2). Porous SiOxThe particles, the poly tannic acid and the conductive agent are in the proportion range, and the conductive agent can be effectively and uniformly distributed on the porous SiOxThe particles are distributed on the surface of the particles and in a film layer formed by the polytannic acid, and the polytannic acid can be completely coated on the porous SiOxThe particles and the surface of the conductive agent are formed to be thinThe silicon-oxygen material has more space, so that the silicon-oxygen material can expand and contract without being crushed or pulverized, and the conductive agent is uniformly distributed on the porous SiOxThe particle surface and the embedding can improve the electrically conductive characteristic of silica material effectively between the polytannic acid layer, and the thin layer SEI film that polytannic acid formed can stop the contact of silica material and electrolyte effectively, avoids the volume when charging and discharging of silica material to change simultaneously.
Preferably, the porous SiOxThe particle size of the particles is 1 nm-10 mu m, the particle size is too large, the porous structure cannot inhibit the amplitude of volume change, micro stress is easily formed on a silica material, so that the silica material is still easy to break and pulverize, the thickness of the shell material is 50-100 nm, namely, the thickness of a poly tannic acid coating layer formed by tannic acid is concentrated between 50 nm-100 nm, and the outer crosslinked poly tannic acid layer has a certain elastic effect, so that the stress change in the charging and discharging process can be relieved, and the pulverization of the silica particles is inhibited.
The silicon-oxygen composite material provided by the invention is prepared from porous SiOxCoating a layer of polytannic acid on the surface of the particles to form a composite material with a core-shell structure, wherein the polytannic acid and porous SiO are coatedxThe conductive agent is embedded among the particles, so that the silica material has good conductive performance and good structural stability, the poly-tannic acid film layer formed by polymerization of tannic acid belongs to an artificial SEI film, the poly-tannic acid film layer has the characteristic of compactness and is beneficial to preventing the silica material from directly contacting with electrolyte, meanwhile, the poly-tannic acid film layer also has good elasticity and can well maintain the structural stability of the silica composite material, the conductive agent embedded in the poly-tannic acid film layer has a good conductive effect on the poly-tannic acid, and when the silica composite material is used as a lithium ion battery cathode active material, the structural stability and the rate characteristic of the silicon-based cathode material can be effectively improved.
In a second aspect, the invention also provides a preparation method of the silicon-oxygen composite material. In one embodiment, the preparation method of the silicon-oxygen composite material comprises the following steps:
step S01, SiOxDissolving the material in an alkaline solution, uniformly mixing, and heating to 30-70 ℃ to enable SiO to be dissolvedxReacting the material with an alkaline solution, separating, washing and drying to obtain an intermediate product;
s02, mixing the intermediate product with tannic acid, a conductive agent and deionized water, and performing ultrasonic treatment to obtain a uniform mixed solution;
and S03, adjusting the pH value of the mixed solution to be alkaline, so that tannic acid is subjected to polymerization reaction, and obtaining the silicon-oxygen composite material.
The above-mentioned preparation method is explained in detail below.
In the above step S01, the alkaline solution may be sodium hydroxide solution or potassium hydroxide solution, SiOxThe material is etched in a sodium hydroxide solution or a potassium hydroxide solution at the temperature of 30-70 ℃, so that SiO is formedxThe material becomes an intermediate product with a porous structure.
In order to make the alkaline solution sufficiently opposite to SiOxEtching the material, adding alkali and SiO in the alkaline solutionxThe mass ratio of the materials is (5-20): (1-5). Alkaline solution to SiOxThe reaction temperature for etching the material is 50-70 ℃, for example, any one of 50 ℃, 55 ℃, 60 ℃, 65 ℃ and 70 ℃, and the etching time is generally about 10 hours. The preferred etching temperature is 60 ℃, the etching time is 10h, the non-uniformity of the holes can be caused by overhigh or overlow temperature and overlong or overlong time, and the SiO can be caused by overlong timexThe material is fully reacted.
Preferably, the concentration of the alkaline solution is (0.1-2) mol/L. The concentration of the alkaline solution is too high, and the etching is too fast, so that the etching degree is not easy to control.
In step S02, there is no particular requirement on the charging sequence of the intermediate product, tannic acid, conductive agent and deionization, and no matter which charging sequence is adopted, the purpose is to coat the tannic acid and conductive agent on the surface of the intermediate product, and the coating effect is the same after ultrasonic treatment. For example, the tannic acid can be dissolved in the deionized water, and then the conductive agent and the intermediate product are sequentially added; or the conductive agent can be dispersed in the deionized water firstly, and then the tannic acid and the intermediate product are added; or firstly adding the intermediate product into deionized water, and then sequentially adding tannic acid and the conductive agent; or simultaneously adding the intermediate product, the tannic acid and the conductive agent into the deionized water. In the ultrasonic treatment process, the temperature is controlled to be-5-0 ℃, and the ultrasonic time is 12-36 hours. The ultrasonic treatment is mainly to disperse the porous silica particles and the conductive agent in the aqueous solution of tannic acid sufficiently and uniformly.
In step S02, the mass ratio of the intermediate product, the tannic acid and the conductive agent is (10-50): (0.5-2): (0.5 to 2);
during feeding, the whole ultrasonic process is maintained at-5 ℃ to 0 ℃ through an ice water bath.
In step S03, the pH can be adjusted by adding a sodium hydroxide solution or a potassium hydroxide solution to the mixed solution, adding an alkaline substance, and minimizing the introduction of impurities so that the pH is greater than 7, at which time the tannic acid undergoes a polymerization reaction, and the produced poly-tannic acid coats the surface of the silica material, and the silica composite material can be obtained without washing.
The preparation method of the silicon-oxygen composite material has simple process, and can prepare the silicon-oxygen composite material with good conductivity and stable structure without complex equipment.
The silica composite material obtained by the method has good conductivity and a stable structure, so that the silica composite material is suitable for being used as a lithium ion battery cathode active material. Because of this, the present invention also provides a lithium ion battery.
Specifically, the lithium ion battery comprises a negative electrode, and the active material on the negative electrode is selected from the silicon-oxygen composite material. The lithium ion battery has good electrochemical performance, and particularly can be charged and discharged at a large multiplying power, and the cycle life is prolonged.
In order to more effectively explain the technical solution of the present invention, the technical solution of the present invention is explained below by a plurality of specific examples.
Example 1
A preparation method of a silicon-oxygen composite material comprises the following steps:
s11, mixing 10.0g of SiO with the average grain diameter of 5 mu mxDissolving the material in 0.625L sodium hydroxide solution, mixing, heating to (40 + -5) deg.C to make sodium hydroxide to SiOxAnd etching the material, and reacting for 12h to form a porous structure, wherein the concentration of the sodium hydroxide solution is 2.0 mol/L.
S12, centrifuging the product obtained by the reaction in the step S11 by using deionized water, washing, and drying at 80 ℃ to obtain an intermediate product.
S13, dissolving 0.5g of tannic acid in deionized water, sequentially adding 0.5g of conductive carbon black (Sp) and 5g of the intermediate product obtained in the step S12, and carrying out ultrasonic treatment at the temperature of 0 ℃ for 24 hours to obtain a uniform mixed solution.
S14, adding a sodium hydroxide solution into the mixed solution obtained in the step S13, adjusting the pH value of the mixed solution to be about 11, carrying out a polymerization reaction on tannic acid to generate poly-tannic acid, coating the poly-tannic acid on the surface of an intermediate product, thus obtaining a silicon-oxygen composite material, and centrifuging and drying the silicon-oxygen composite material for later use.
Example 2
A preparation method of a silicon-oxygen composite material comprises the following steps:
s21, mixing 5.0g of SiO with the average grain diameter of 5 mu mxDissolving the material in 0.25L sodium hydroxide solution, mixing, heating to 40 + -5 deg.C to make sodium hydroxide to SiOxAnd etching the material, and reacting for 15h to form a porous structure, wherein the concentration of the sodium hydroxide solution is 2.0 mol/L.
S22, adopting deionized water to carry out centrifugation and washing on the product obtained by the reaction in the step S21, and drying at 80 ℃ to obtain an intermediate product.
S23, dissolving 0.3g of tannic acid in deionized water, sequentially adding 0.3g of conductive carbon black (Sp) and 3.0g of the intermediate product obtained in the step S22, and carrying out ultrasonic treatment at the temperature of 0 ℃ for 24 hours to obtain a uniform mixed solution.
S24, adding a sodium hydroxide solution into the mixed solution obtained in the step S23, adjusting the pH value of the mixed solution to be about 11, carrying out a polymerization reaction on tannic acid to generate poly-tannic acid, coating the poly-tannic acid on the surface of an intermediate product, thus obtaining a silicon-oxygen composite material, and centrifuging and drying the silicon-oxygen composite material for later use.
Example 3
A preparation method of a silicon-oxygen composite material comprises the following steps:
s31, mixing 10.0g of SiO with the average grain diameter of 5 mu mxDissolving the material in 0.625L sodium hydroxide solution, mixing, heating to (40 + -5) deg.C to make sodium hydroxide to SiOxAnd etching the material, and reacting for 12h to form a porous structure, wherein the concentration of the sodium hydroxide solution is 2.0 mol/L.
S32, centrifuging and washing a product obtained by the reaction in the step S31 by using deionized water, and drying at 80 ℃ to obtain an intermediate product.
S33, dissolving 0.6g of tannic acid in deionized water, sequentially adding 0.3g of conductive carbon black (Sp) and 3.0g of the intermediate product obtained in the step S32, and carrying out ultrasonic treatment at the temperature of 0 ℃ for 24 hours to obtain a uniform mixed solution.
S34, adding a sodium hydroxide solution into the mixed solution obtained in the step S33, adjusting the pH value of the mixed solution to be about 11, carrying out a polymerization reaction on tannic acid to generate poly-tannic acid, coating the poly-tannic acid on the surface of an intermediate product, thus obtaining a silicon-oxygen composite material, and centrifuging and drying the silicon-oxygen composite material for later use.
The materials of comparative example 1 and comparative example 2 are also provided for comparison.
Among them, the material of comparative example 1 is a commercial carbon-coated silica material (SiO)x@ C); the material of comparative example 2 was prepared by coating the surface of silica material with poly tannic acid (SiO)x@ tannin).
In order to verify the properties of the materials obtained in examples 1 to 3 and comparative examples 1 to 2, the following performance tests were carried out.
Scanning Electron Microscopy (SEM)
The products obtained in step S12 and step S14 of example 1 were scanned by an TESCAM MIRA3 scanner, and the results are shown in fig. 1 and 2.
As can be seen from FIG. 1, SiO was etched with NaOHxThe material is porous, and when the material is used as a negative electrode active material to prepare a lithium ion battery, lithium ion migration is facilitated, so that damage to a silica material structure in the charging and discharging process is reduced. As can be seen from FIG. 2, porous SiOxThe material is coated with polytannic acid to obtain porous SiOxThe surface of the material is coated with a layer of compact poly-tannic acid, and the poly-tannic acid is used as an artificial SEI film, so that the rate and the stability of the material are obviously improved.
The silicon oxygen composite material prepared in step S24 of example 2 was SEM-scanned using an TESCAM MIRA3 apparatus while simultaneously taking an energy spectrum (EDS), and the results are shown in fig. 3.
Comparing FIGS. 3, 2 and 1, it can be clearly seen that the porous SiO is originally coated with the polytannic acidxThe surface is coated with a compact coating layer, which is shown in detail in fig. 3(a), so that the contact between the active material and the electrolyte can be sufficiently isolated; the corresponding EDS image can find the phenomena of holes and coating, which has obvious effect on improving the multiplying power and the stability of the material, and is shown in figure 3 (b); as shown in FIG. 3(c), SiO was used as the starting materialxPorous SiOxAnd porous SiOx@ Polytannic acid&The mass ratio of O/Si of Sp is firstly reduced and then increased, which respectively correspond to the etching process and the coating process and accord with the experimental rule.
(III) cycle performance curve of lithium ion battery
The silicon-oxygen composite materials prepared in examples 1 and 2 and the SiO of comparative example 1x@ C SiO of comparative example 2x@ poly tannic acid as a positive electrode active material, a metal lithium sheet as a negative electrode, and an electrolyte of FEC: PC: DEC ═ 1:1:4(v: v), LiPF6(1M) and 2400 separators, respectively assembling 2025 type lithium ion batteries, standing, performing charging and discharging 3 times at Xinwei electrochemical workstation according to a small current of 0.05C to form a uniform and compact SEI film, and performing cycle test and corresponding rate performance test according to a current of 0.1C-2C.
The results are shown in FIGS. 4 and 5. As can be seen from fig. 4, the lithium ion battery prepared in example 1 has a discharge capacity of over 1200mAh/g in a cycle curve at a current of 0.2C, and the material can be stable for a long time.
As can be seen from FIG. 5, the cyclic stability of the silicon oxide composite material obtained in example 2 with respect to the materials of comparative examples 1 and 2 is due to the porous SiOxProvides a large number of migration channels of Li ions, and simultaneously forms an outer layer and SiOxThe conductive carbon black with good conductivity is arranged between the two layers, the outer layer is a poly tannic acid layer with elastic characteristic, and the three layers have obvious effects on maintaining the structure and performance stability of the material.
(IV) Large Rate Charge/discharge test
The silicon-oxygen composite materials prepared in examples 1 and 2 and the SiO of comparative example 1x@ C SiO of comparative example 2x@ poly tannic acid as a positive electrode, a metal lithium sheet as a negative electrode, and an electrolyte of FEC: PC: DEC ═ 1:1:4(v: v), LiPF6(1M) and 2400 separators, respectively assembling 2025 type lithium ion batteries, standing, performing charge and discharge for 3 times at Xinwei electrochemical workstation according to a small current of 0.05C to form a uniform and compact SEI film, and then performing magnification performance test.
As can be seen from fig. 6, the lithium ion battery assembled by the silicone-oxygen composite material of example 2 has capacities of 1645mAh/g, 1453mAh/g, 1234mAh/g, 876mAh/g, and 774mAh/g at 0.1C, 0.2C, 0.5C, 1C, and 2C, respectively, and has good rate capability, and specific capacities of comparative example 1 and comparative example 2, which indicates that the outer-coated poly tannic acid and the conductive carbon black have higher ion mobility and conductivity.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. The preparation method of the silica composite material is characterized in that the silica composite material is a composite material with a core-shell structure, and the core layer material is porous SiOxParticles, the shell material being polytannic acid, and the core material and the shell material being in betweenEmbedding a conductive agent; wherein x is more than 0 and less than 2, and the preparation method of the silicon-oxygen composite material comprises the following steps:
step S01, SiOxDissolving the material in an alkaline solution, uniformly mixing, and heating to 30-70 ℃ to enable SiO to be dissolvedxReacting the material with an alkaline solution, separating, washing and drying to obtain an intermediate product; the alkaline solution is any one of sodium hydroxide solution and potassium hydroxide solution, and the alkali and SiO in the alkaline solution are addedxThe mass ratio of the materials is (5-20): (1-5);
s02, mixing the intermediate product with tannic acid, a conductive agent and deionized water, and performing ultrasonic treatment to obtain a uniform mixed solution;
and S03, adjusting the pH value of the mixed solution to be alkaline, so that the tannic acid is polymerized to obtain the silicon-oxygen composite material.
2. The method for producing a silicone composite material according to claim 1, wherein the concentration of the alkaline solution is (0.1 to 2) mol/L.
3. The preparation method of the silicone composite material according to claim 1, wherein in the ultrasonic treatment of step S02, the temperature is controlled to be-5 ℃ to 0 ℃, and the ultrasonic time is (12) to 36) hours.
4. The method for producing a silicone composite material according to claim 1, wherein in step S02, the mass ratio of the intermediate product, the tannic acid, and the conductive agent is (10 to 50): (0.5-2): (0.5 to 2);
the conductive agent is selected from at least one of carbon black, carbon nano tubes and graphene.
5. The method for producing a silicon-oxygen composite material according to any one of claims 1 to 4, wherein the porous SiO is contained in the silicon-oxygen composite material at a mass ratioxAnd (3) particle: poly tannic acid: conductive agent = (10 to 50): (0.5-2): (0.5-2).
6. As claimed inThe method for producing a silica composite material according to any one of claims 1 to 4, wherein the porous SiO isxThe particle size of the particles is 1 nm-10 mu m, and the thickness of the shell material is 50 nm-100 nm.
7. The method for preparing a silicone composite material according to any one of claims 1 to 4, wherein the conductive agent is at least one selected from carbon black, carbon nanotubes, and graphene.
8. A lithium ion battery comprises a negative electrode, and is characterized in that an active material of the negative electrode is prepared by the preparation method of the silicon-oxygen composite material of any one of claims 1 to 7.
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