KR20140036495A - Silicon-based complex composite in use of anode material for secondary battery, and manufacturing method thereof - Google Patents

Abstract

Disclosed is a silicon based composite material which can be used as a negative electrode material of secondary battery. The silicon based composite material is manufactured through the followings: a first step of forming a porous material by mixing silicon chloride and glycol which is a bivalent alcohol type; a second step of forming a silicon oxide which is indicated as general formula: SiOx, and in which an oxygen content is in the range of 0<x<2 by heat treating the porous material in the inert atmosphere; a third step of forming a composite powder of Si-SiOx by performing a solid state reaction after mixing the silicon oxide which is formed in the second step and metal silicon; a fourth step of forming a composite material of Si-SiOx-C by performing a solid state reaction after mixing the composite powder of Si-SiOx which is formed in the second step and carbon material; a fifth step of heat treating the composite material of Si-SiOx-C in the inert atmosphere at the temperature range of more than the reduction reaction temperature and less than the alloying reaction temperature. [Reference numerals] (AA) Charge and discharge capacity; (BB) Charge; (CC) Discharge; (DD) Number of cycles

Description

High capacity silicon-based composite material for negative electrode material of secondary battery and manufacturing method thereof

The present invention relates to a negative electrode material for improving the energy density of a secondary battery requiring a high output and a high voltage, and more particularly, to a negative electrode material having a high capacity for improving energy storage characteristics of a middle- or large- will be.

Silicon reacts with lithium to produce Li ₁₂ Si ₅ And the theoretical capacity reaches 4008 mAh / g. Therefore, it has attracted attention as a new material capable of overcoming the limitations of existing lithium secondary batteries because it exhibits a high capacity more than 10 times that of graphite. However, the silicon depletes the electrode due to a volume change of more than 300% during charging and discharging, and most of the capacity is lost within 10 cycles. As described above, the alloy-based negative electrode material having a high capacity can not be easily commercialized because the materials undergo continuous expansion and contraction during charging and discharging, resulting in loss of electrical contact, thereby rapidly increasing the electrode resistance .

In order to solve this problem, a method of using an active / inactive compound or a composite containing an inactive material capable of buffering a volume change without reacting with lithium has been studied. In particular, materials other than silicon, such as silicon, are superior in electric conductivity to silicon, so that an increase in electrode resistance can be suppressed and the active material can be dispersed evenly inside, thereby reducing the stress caused by the volume change. Therefore, it has a possibility of securing excellent reversibility than when using a silicon active material. However, when a material other than silicon is used as an alloying material, the maximum capacity or the limit capacity is reduced, so that the cycle characteristics and capacity can not be simultaneously pursued.

In order to overcome the problems of silicon, many researchers have been studying the addition of metals such as copper, lithium, and iron or the combination with carbonaceous materials to solve problems of excessive volume change and improvement of cycle life characteristics However, there is still a need for development for commercialization.

The present invention relates to a negative electrode active material for a lithium secondary battery used for an electric vehicle and an energy storage system, and more particularly, to a silicon composite material containing metal silicon, silicon oxide and carbon as a high capacity negative electrode active material for replacing a conventional graphite negative electrode material, And a method for producing the same.

Another object of the present invention is to provide a negative electrode material for a secondary battery having a high capacity and a method of manufacturing a silicon composite material containing silicon oxide having an oxygen content of less than 2, And to provide a method for producing a silicon-based composite material which can be easily controlled at a nano-size.

The method for manufacturing a silicon-based composite material for a negative electrode material of a secondary battery according to the present invention comprises: a first step of mixing a silicon chloride and a glycol as a dihydric alcohol to form a porous material; A second step of forming a silicon oxide represented by the general formula SiOx wherein the content (x) of oxygen is in the range of 0 < x < 2 by subjecting the porous material to heat treatment in an inert gas atmosphere; A third step of forming a composite powder of Si-SiOx by mixing and solid-reacting the silicon oxide and the metal silicon formed in the second step; A fourth step of forming a composite material of Si-SiOx-C by mixing and solid-reacting the carbonaceous material with the Si-SiOx composite powder formed in the third step; And a fifth step of heat-treating the composite material of Si-SiOx-C in an inert gas atmosphere at a temperature lower than the reduction reaction temperature of carbon and lower than an alloy reaction temperature of silicon and carbon.

In particular, in the first step, the content of the silicon chloride is preferably 10 parts by weight or more and 90 parts by weight or less based on 100 parts by weight of the total mixture of the silicon chloride and the glycol. Here, the silicon chloride may be at least one selected from the group consisting of silicon tetrachloride and dialkyldichlorosilane. Further, the glycol may be at least one selected from the group including ethylene glycol, propylene glycol, and pinacol.

Furthermore, it is preferable that the heat treatment performed in the second step is performed at a temperature of 600 ° C or higher and 900 ° C or lower.

In the third step, the content of the silicon oxide is preferably 2 parts by weight or more and 98 parts by weight or less based on 100 parts by weight of the mixed powder of the silicon oxide and the metal silicon.

In addition, it is preferable that the heat treatment performed in the fifth step is performed at a temperature of 800 ° C or more and less than 1,000 ° C.

In the fourth step, the content of the Si-SiOx composite powder is preferably 5 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of the total of the Si-SiOx composite powder and the carbonaceous material.

The silicon-based composite material for a negative electrode material of a secondary battery according to the present invention comprises: a silicon oxide represented by the general formula SiOx in which the content (x) of oxygen is within a range of 0 < x < Metal silicon; And a carbonaceous material. Here, the silicon oxide powder represented by the general formula SiOx and the silicon metal powder having the oxygen content (x) in the range of 0 < x < 2 are solid-phase reacted to form a Si-SiOx composite powder, And the carbon material are solid-phase reacted to form a composite material of Si-SiOx-C. The Si-SiOx-C composite thus formed is heat-treated in an inert gas atmosphere at a temperature not lower than the reduction reaction temperature of carbon and lower than the reaction temperature of the reaction between silicon and carbon, and finally, the silicon composite material according to the present invention is formed.

The silicon-based composite material according to the present invention may include metal silicon, silicon oxide having less than 2 oxygen atoms, and carbon, and such a silicon-based composite material can be advantageously used particularly as an anode material of a lithium secondary battery.

In the case of using the silicon-based composite material containing metal silicon, silicon oxide having less than 2 oxygen atoms, and carbon as an anode material of a secondary battery by the method according to the present invention, the carbon in the matrix on the base reacts with the Si-SiOx composite powder and oxygen The irreversible reaction of silicon can be suppressed and the reactivity of the silicon metal with lithium can be improved.

Further, according to the process for producing a silicon-based composite material according to the present invention, the particle size can be easily controlled and the irreversibility of the negative electrode material can be suppressed in manufacturing the negative electrode material used in the middle- or large-sized secondary battery and the high- It is very effective in producing a high-capacity powder that can dramatically improve energy storage characteristics.

1 is an electron micrograph of a silicon composite material produced according to the present invention.
2 shows an XRD diffraction pattern for confirming the crystal structure of the silicon-based composite material produced by the present invention.
Fig. 3 shows the results of the electrochemical property evaluation of the silicon-based composite material produced by the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a silicon-based composite material including metal silicon, silicon oxide having less than 2 oxygen atoms and carbon material, and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

First, a silicon-based composite material according to the present invention is a Si-SiOx composite powder formed by solid-phase reaction of a silicon oxide powder and a metal silicon powder represented by a general formula SiOx in which the content (x) of oxygen is in the range of 0 < And a solid-reacted carbon material with the Si-SiOx composite powder. Particularly, the content (x) of oxygen in the silicon oxide is more preferably in the range of 0.1? X? 1.9.

The silicon-based composite material according to the present invention can be produced by the following method. That is, the method for producing a silicon-based composite material according to the present invention comprises the steps of: forming a porous material by mixing silicon chloride and glycol as a first step; and heat-treating the porous material in an inert gas atmosphere as a second step Forming a silicon oxide represented by the general formula SiOx in which the content (x) of oxygen is in the range of 0 < x <2; and, as a third step, mixing the silicon oxide and the metal silicon formed in the second step, Forming a composite material of Si-SiOx-C by mixing and solid-reacting the carbonaceous material with the Si-SiOx composite powder formed in the third step, as a fourth step, The composite material of Si-SiOx-C is heated in an inert gas atmosphere at a temperature lower than the reduction reaction temperature of carbon and lower than the reaction temperature of silicon and carbon alloy And a heat treatment step.

Particularly, in the third step, silicon oxide having a produced oxygen number of less than 2 and metal silicon in a bulk state having an average particle diameter of 200 mu m or less are mixed in a ratio range of 2: 98 to 98: 2, Are put into a ball mill to cause a solid phase reaction to produce a composite powder. At this time, it is preferable that the rotation speed of the ball mill is in the range of 50 rpm to 2000 rpm in the solid state reaction, and the solid phase reaction time is limited to 30 minutes to 6 hours. Particularly, the weight ratio of silicon oxide and metal silicon is more preferably 30:70, and the rotation speed is preferably 150 rpm for 2 hours.

On the other hand, in the fourth step, the produced Si-SiOx (0 < x < 2) composite powder is combined with a carbonaceous material. Here, in the complexing step, the weight ratio of Si-SiOx composite powder and carbon is set at a weight ratio of 1:99 to 99: 1, more preferably 5:95 to 20:80, Solid state reaction is carried out for a period of time to produce a composite of SiOx-Si-C. The composite process is a pretreatment for the final production of a silicon-based composite material. If the solid-phase reaction of the Si-SiOx composite powder and carbon in the composite process is not satisfactory, the reduction reaction of the composite material in the subsequent final heat- So that the volume expansion due to carbon is not suppressed. When the rotation speed of the milling machine is less than 50 rpm when the Si-SiOx composite powder and the carbonaceous material are mixed in the composite process, the composite material is not mixed smoothly and the composite material is not formed. When the rotation speed is more than 500 rpm, is due to the destruction and pressure contact by the energy in the SiOx in the composite material the transformation of SiO ₂ can be promoted.

Next, as a fifth step, the produced SiOx-Si-C composite material is heat-treated in an inert gas atmosphere using an electric furnace. At this time, argon (Ar), nitrogen, or hydrogen gas may be preferably used as the inert gas. Here, the heat treatment temperature is set within the range of 800 to 1000 ° C., the temperature is increased by 1 to 10 ° C. per minute, the final temperature is maintained for 30 minutes to 3 hours, and the resultant is further cooled by 1 to 10 ° C. to obtain the final product. When the heat treatment temperature is lower than 800 ° C, the reduction heat treatment is insufficient and the carbon base is not generated uniformly. If the temperature is higher than 1,000 ° C, CO is formed due to the reaction between carbon and Si- A desired silicon-based composite material is not formed. More preferably, it is most preferable to increase the temperature to 900 DEG C by 5 DEG C per minute, maintain the temperature at 900 DEG C for 1 hour, and further cool down by 5 DEG C / minute. On the other hand, when the temperature is increased or cooled to 1 ° C or less, productivity is deteriorated due to a long heat treatment. When the temperature is increased or cooled to 10 ° C or more, There is a problem that it is not realized.

Hereinafter, the method for producing the composite powder including the above-described metal silicon and silicon oxide will be described in more detail.

[Preparation of Porous Material]

First, to produce a porous material as an initial material for the formation of silicon oxide (SiOx; 0 < x < 2) with an oxygen content of less than 2, 2, which is a dihydric alcohol. Examples of the silicon chloride having a purity of 90% or more include silicon tetrachloride (silicon tetrachloride), dialkyldichlorosilane (RRSiCl2; Diacyldichlorosilane] and the like can be used. As the glycol, all alcohols represented by R (OH) 2, for example, ethylene glycol, propylene glycol, pinacol and the like can be used. Silicon chloride and glycols are rapidly mixed to produce a porous material. In the mixing sequence, a large amount of a porous material in the form of a sponge can be produced by rapid reaction when silicon chloride is added to the glycol. Conversely, glycol may be added to the silicon chloride, in which case the porous material and the sol-state liquid material may be formed together. In the reaction of silicon chloride with glycol, the reaction rate can be controlled within a chemical weight ratio, and can be adjusted to have a reaction time of 1 minute to 60 minutes in consideration of rapid mixing time and weight ratio in real time mixing.

On the other hand, the mixing ratio of silicon chloride and glycol is adjusted so as to be in the range of 0.1: 0.9 to 0.9: 0.1 in order to produce HCl through hydrogen reaction of chlorine and glycol in the silicon chloride so that the silicon oxide can be produced easily. do. Here, when the weight ratio of the silicon chloride to 100 parts by weight of the entire mixture of silicon chloride and glycol is less than 10 parts by weight, the oxidation reaction in the silicon can not be performed smoothly and silicon oxide can not be formed. If the weight ratio of the silicon chloride to the whole mixture exceeds 90 parts by weight, the chlorine reaction in the glycol explosively increases and the silicon oxide can be dissolved.

[Heat treatment of porous material]

The porous material produced by the above-described method is subjected to heat treatment to produce silicon oxide having an oxygen content of less than 2. More specifically, the produced porous material is heat-treated in an inert gas atmosphere using a mixed gas of hydrogen, nitrogen, argon, or a mixture of these three gases. For example, the produced porous material is heat-treated at 600 ° C to 900 ° C for 15 minutes to 6 hours in a vertical, horizontal, or heat treatment furnace including a conveyor belt. During the heat treatment, the chlorine gas is evaporated by the reaction of chlorine in the silicon chloride with carbon in the glycol, and by the reaction of the silicon cluster in the silicon chloride with oxygen in the glycol, a silicon oxide having an oxygen number less than 2 is produced. Here, the inert gas atmosphere is maintained because an oxidizing atmosphere for forming a silicon oxide having less than 2 oxygen atoms is not formed when an oxidizing gas or a reducing gas is included.

On the other hand, when the heat treatment temperature is lower than 600 ° C, the reaction rate of chlorine and hydrogen is lowered, so that the chlorine gas is not removed smoothly and silicon oxide is not easily formed. On the other hand, if the temperature exceeds 900 ° C., the particle size of the generated silicon oxide may grow and eventually the activity of the secondary battery may deteriorate. Also, due to the explosive generation of chlorine gas, An oxide having a valence of 2 or more can be produced. If the heat treatment temperature is less than 15 minutes, formation of silicon oxide is not easy, and if it exceeds 6 hours, particle growth problem may occur. During the cooling after the heat treatment, it is preferable to perform air cooling or slow cooling to 20 ° C or less per minute because excessive quenching may cause problems of degradation of electrochemical characteristics due to grain size growth.

[Powder Collection and Control of Particle Size]

The silicon oxide prepared by the above-mentioned method is composed of a bulk material as a porous material. The bulk of the bulk state is a state in which nanoparticles are aggregated and must be formed in powder form for application to a secondary cell and control of particle size. For this purpose, it is desirable to control the particle size of the bulk silicon oxide mass produced through the ball mill. In the case of a ball mill, it is preferable to control the rotation speed to 300 rpm or less and the ball mill time to 12 hours or less since the electrochemical characteristics may deteriorate when the particle size is extremely fine.

[Solid phase reaction of silicon oxide and bulk metal silicon]

Next, the silicon oxide (i. E., Silicon monoxide) prepared above is mixed with the bulk silicon metal. The metal silicon in the bulk state is preferably a metal silicon powder having an average particle diameter of 10 nm or more and 200 mu m or less, for example. The thus-prepared silicon oxide powder and metal silicon powder were charged into alumina pores and then charged at 150 rpm for 2 hours using an Attritor, Planatery, Spex, Ball Miller, Mixer ), Etc., and subjected to a solid-phase reaction at room temperature to produce a composite powder of silicon oxide and metal silicon. By such solid phase reaction, the silicon oxide powder and the metal silicon powder form a composite powder physically bonded to each other.

In the solid-phase reaction, the weight ratio of silicon oxide to metal silicon is limited to a range of 2: 98 to 98: 2, the rotation speed is set to 50 rpm to 2,000 rpm, and the solid phase reaction time is limited to 30 minutes to 6 hours . Particularly, when the content of silicon oxide is less than 2 parts by weight based on 100 parts by weight of the mixed powder of silicon oxide and metal silicon, silicon oxide is not distributed in the metal silicon powder base, and the capacity increasing effect can not be obtained. If the content of the silicon oxide exceeds 98 parts by weight, the reaction between the bulk metal silicon and oxygen does not progress smoothly, and irreversibility can not be suppressed. Particularly, the weight ratio of silicon oxide (SiOx; 0 <x <2) to metal silicon is more preferably 30:70.

On the other hand, when the rotational speed is less than 50 rpm, composite powdering does not occur, so that bulk metallic silicon and silicon oxide are separated and a composite powder can not be formed. When the rotation speed exceeds 2,000 rpm, the nano-scale of the composite powder occurs, and irreversible inhibition effect due to the reaction of bulk silicon metal and oxygen can not be obtained. Further, if the solid phase reaction time is less than 30 minutes, the composite powder does not occur. If the reaction time is more than 6 hours, the powder particles are refined in spite of the low rotational speed, so that oxidation of the composite powder proceeds rapidly. On the other hand, since the bulk metal silicon is not reacted with oxygen, it can be mixed in the air, and preferably, it can be mixed in an inert atmosphere.

[Solid phase reaction of Si-SiOx composite powder and carbon material]

Next, the composite powder body of Si-SiOx (0 < x < 2) prepared as described above is mixed with the carbonaceous material. For example, a Si-SiOx composite powder and a carbonaceous material are put into a 50 ml block mouth bottle together with 10 zirconia balls (about 5 mm), and a low energy ball mill is performed for 12 hours at a speed of 100 rpm through a ball mill, To form a composite of SiOx-Si-C. That is, by the solid-state reaction, a composite material of Si-SiOx-C, in which the composite powder of Si-SiOx and the carbon material are physically bonded again, is formed.

Examples of the carbon material include a carbon pitch, a carbon nanotube (CNT), a carbon nanofiber (CNF), a graphene, a graphite, and the like. Can be used. The mixing ratio (Si-SiOx: Carbon) of the composite powder body of Si-SiOx (0 <x <2) and the carbonaceous material is set in the range of 1:99 to 99: 1. When the content of the composite powder body (Si-SiOx) is less than 1 part by weight based on 100 parts by weight of the total weight of the composite powder and the carbonaceous material, Si-SiOx is insufficient in the finally formed silicone composite material, Smooth intercalation of the image is not caused. If the content of the composite powder (Si-SiOx) exceeds 99 parts by weight based on 100 parts by weight of the total weight of the composite powder and the carbonaceous material, the proportion of Si-SiOx in the finally formed silicon- So that the volume expansion can not be suppressed smoothly. More preferably, the weight ratio of the Si-SiOx composite powder to the carbonaceous material can be adjusted in the range of 5:95 to 20:80.

[Heat Treatment of SiOx-Si-C Composite]

The SiOx-Si-C composite thus formed is transferred into an alumina crucible and heat treatment is performed in an inert gas atmosphere using a reducing furnace. At this time, argon (Ar), nitrogen, hydrogen or the like can be preferably used as the inert gas. In addition, the heat treatment temperature in the reduction heat treatment process is controlled within a temperature range above the reduction reaction temperature of carbon and below the alloying reaction temperature of silicon and carbon. Preferably, the reduction heat treatment of the mixed powder of silicon and carbon is carried out at a temperature in the range of 800 ° C or more and less than 1,000 ° C. Preferably, the heat treatment temperature is higher than the reduction reaction temperature of carbon, and if the heat treatment temperature is lower than 800 ° C, the reduction heat treatment is not easy and the carbon base is not produced smoothly. The heat treatment temperature is preferably lower than the alloying reaction temperature of silicon and carbon. If the heat treatment temperature is higher than 1,000 ° C, carbon oxide (CO) can be formed by the reaction of carbon with oxygen of Si-SiOx.

FIGS. 1, 2, and 3 show the results of performing electron microscopy, X-ray diffraction analysis, and electrochemical characteristics evaluation of the Si-SiOx-C composite material produced by this embodiment.

As shown in FIG. 1, it can be seen that the Si-SiOx-C composite produced by the present invention has an average particle diameter in the range of 50 μm to 150 μm, and it can be confirmed that carbon is coated on the matrix.

On the other hand, as shown in FIG. 2, even after the Si-SiOx-C composite material is formed, the SiOx retains the crystal structure of the conventional silicon monoxide, and the composite phase is easily prepared through the absence of crystallization of carbon and silicon .

As a result of the electrochemical property evaluation of the silicon-based composite material produced by the present invention, it can be seen that the capacity of 630 mAh / g, which is the initial capacity, is maintained after 40 cycles. It can be confirmed that the bulk expansion is almost suppressed compared to the conventional SiOx powder, and it is confirmed that the capacity is about twice as high as that of the conventional carbon material.

These results suggest that the carbon in the matrix can inhibit the irreversible reaction of silicon by suppressing the reaction between Si-SiOx and oxygen through the formation of composite material of Si-SiOx composite powder and carbon. In addition, in the present silicon-based composite material, the reactivity with the lithium (Li) of the silicon (Si) metal is improved, and furthermore, the space in which the lithium can be inserted into the grain boundary of the SiOx is sufficient. And a stable crystal phase can be maintained.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. It is therefore to be understood that the embodiments of the invention described herein are to be considered in all respects as illustrative and not restrictive, and the scope of the invention is indicated by the appended claims rather than by the foregoing description, Should be interpreted as being included in.

Claims (12)

A first step of mixing a silicon chloride and a glycol as a dihydric alcohol to form a porous material;
A second step of forming a silicon oxide represented by the general formula SiOx wherein the content (x) of oxygen is in the range of 0 < x < 2 by subjecting the porous material to heat treatment in an inert gas atmosphere;
A third step of forming a composite powder of Si-SiOx by mixing and solid-reacting the silicon oxide and the metal silicon formed in the second step;
A fourth step of forming a composite material of Si-SiOx-C by mixing and solid-reacting the carbonaceous material with the Si-SiOx composite powder formed in the third step; And
And a fifth step of heat-treating the composite material of Si-SiOx-C in an inert gas atmosphere at a temperature lower than the reduction reaction temperature of carbon and a temperature lower than an alloy reaction temperature of silicon and carbon. Way.
The method of claim 1,
In the first step, the content of the silicon chloride is 10 parts by weight or more and 90 parts by weight or less based on 100 parts by weight of the total mixture of the silicon chloride and the glycol. .
The method of claim 1,
Wherein the silicon chloride is at least one selected from the group consisting of silicon tetrachloride and dialkyldichlorosilane. 2. The method of claim 1, wherein the silicon chloride is at least one selected from the group consisting of silicon tetrachloride and dialkyldichlorosilane.
The method of claim 1,
Wherein the glycol is at least one selected from the group consisting of ethylene glycol, propylene glycol, and pinacol.
The method of claim 1,
Wherein the heat treatment is performed at a temperature of 600 ° C or more and 900 ° C or less in the second step.
The method of claim 1,
In the third step, the content of the silicon oxide is not less than 2 parts by weight and not more than 98 parts by weight based on 100 parts by weight of the mixed powder of the silicon oxide and the metal silicon. Way.
The method of claim 1,
In the fourth step, the content of the Si-SiOx composite powder is not less than 7 parts by weight and not more than 20 parts by weight based on 100 parts by weight of the total amount of the Si-SiOx composite powder and the carbonaceous material. A method for producing a silicon based composite material for a negative electrode material.
The method of claim 1,
Wherein the heat treatment is performed at a temperature of 800 DEG C or more and less than 1,000 DEG C in the fifth step.
Silicon oxide powder represented by general formula SiOx in which an oxygen content (x) is in a range of 0 <x <2; Metal silicon powder; And a carbon material powder; wherein the silicon oxide powder, the metal silicon powder, and the carbon material powder are bonded to each other by solid phase reaction.
Si-SiOx composite powder formed by the solid-state reaction of the silicon oxide powder and the metal silicon powder represented by the general formula SiOx having an oxygen content (x) in the range of 0 <x <2; And a carbon material powder in which the Si-SiOx composite powder and the solid phase react with each other to be bonded to each other.
11. The method of claim 10,
The content of the silicon oxide powder is 2 parts by weight or more and 98 parts by weight or less based on 100 parts by weight of the total of the silicon oxide powder and the metal silicon powder.
The content of the Si-SiOx composite powder is 5 parts by weight or more and 20 parts by weight or less with respect to a total of 100 parts by weight of the Si-SiOx composite powder and the carbon material powder. .
A lithium secondary battery comprising a negative electrode formed by using the silicon-based composite according to claim 9.

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