KR102206625B1 - LITHIUM-PRE DOPED SiOx PARTICLE FOR ANODE MATERIAL OF LITHIUM SECONDARY BATTERY AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Abstract

Disclosed is a method of preparing SiO _x particles for a negative electrode material of lithium pre-doped lithium secondary battery, which increases initial reversible efficiency by pre-doping lithium to form an irreversible phase such as lithium oxide and lithium silicon oxide.
The manufacturing method of SiO _x particles for lithium pre-doped lithium secondary battery negative electrode material according to the present invention comprises the steps of: (a) inducing silicon (Si) to induce melting to form silicon in a molten metal state; And (b) supplying a lithium source and an oxidation source for silicon in the molten state, SiO _x step of pre-doping of lithium in the particles; including, said SiO _x lithium oxide or / in the step of pre-doping of lithium in the particles And an irreversible phase comprising lithium silicon oxide.

Description

Lithium pre-doped SiOx particle for negative electrode material of lithium secondary battery and its manufacturing method {LITHIUM-PRE DOPED SiOx PARTICLE FOR ANODE MATERIAL OF LITHIUM SECONDARY BATTERY AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a SiO _x particle for a lithium secondary battery negative electrode material including an irreversible phase in advance by pre-doping lithium and a manufacturing technology thereof.

While the demand for secondary batteries is increasing, application fields of secondary batteries are expanding into electric vehicles and energy storage systems.

The improvement of lithium secondary battery performance is based on the components of the positive electrode, negative electrode and electrolyte. Among them, graphite, which is mainly used as an anode material, has a theoretical capacity of 370 mAh/g, so the development of anode materials such as silicon, silicon oxide (SiO _x ), tin, and aluminum as a material to replace the graphite anode material is being studied. .

Among them, silicon has a theoretical capacity of 4200 mAh/g and is attracting attention as a new material capable of overcoming the limitations of existing lithium secondary batteries because it has a high capacity of almost 10 times that of graphite.

However, in the process of alloying with lithium, silicon causes a swelling phenomenon while continuously repeating expansion and contraction due to a volume expansion rate of more than 300%, and thus cracks occur inside and on the electrode. Accordingly, there is a problem in that the cycle capacity rapidly decreases due to a decrease in electrical contact.

On the other hand, SiO _x has a high mechanical strength due to the oxide formed in the initial charging and discharging process. Accordingly, it has stability against volume expansion that occurs during charging and discharging, and thus it is possible to solve the life problem.

However, SiO _x has a large initial irreversible capacity due to Li ₂ O, Li ₂ Si ₂ O ₅ , Li ₂ SiO ₃ , and Li ₄ SiO _4, etc., which are generated during the initial charging of the negative electrode of lithium ions. These oxides are irreversible, and once made, the consumed lithium cannot be reused. The irreversible phase occupies more than 20% of the total, and the initial reversible efficiency is less than 80%. Accordingly, there is a problem that the initial reversible efficiency decreases, and commercialization is impossible.

In order to solve this problem, a technology has been developed to increase initial reversible efficiency by adding lithium to SiO _x in advance, and this is called lithium pre-doping or pre-lithiation process. Most existing technologies maximize efficiency by adding lithium to the anode or cathode in the form of a metal. In this case, the amount of lithium metal that forms the initial irreversible phase is mixed with the electrode in advance to compensate for the irreversible phase, and this is called active pre-lithiation.

However, in the case of such active pre-lithiation, lithium metal can generate heat and gas by exothermic reaction with moisture in air. As a result, the inside of the battery expands, causing a problem in the stability of the battery. In addition, when the lithium metal for mixing in the electrode is manufactured in the form of particles, the manufacturing process is complicated and the manufacturing cost is high. In addition, there is a problem in that the storage period of the electrode is extremely short due to the instability of lithium metal in the manufactured electrode.

Therefore, there is a need for research on a negative electrode material that can improve the initial reversible efficiency of the battery and can be stored for a long time.

Republic of Korea Patent Publication 10-1430640 (2014.08.14. Announcement)

An object of the present invention is to provide a lithium-pre-doped SiO _x particle for a negative electrode material of a lithium secondary battery capable of improving initial charging and discharging efficiency by forming an irreversible phase in advance.

In addition, an object of the present invention is to provide a method for producing SiO _x particles for a negative electrode material for a secondary battery capable of pre-doping lithium by adding a lithium source in a process using an induction melting method.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention that are not mentioned can be understood by the following description, and will be more clearly understood by examples of the present invention. In addition, it will be easily understood that the objects and advantages of the present invention can be realized by the means shown in the claims and combinations thereof.

According to a first embodiment of the present invention, (a) forming silicon in a molten state by induction melting silicon (Si); And (b) supplying a lithium source and an oxidation source for silicon in the molten state, SiO _x step of pre-doping of lithium in the particles; including, said SiO _x lithium oxide or / in the step of pre-doping of lithium in the particles And it provides a method of producing SiO _x particles in which an irreversible phase including lithium silicon oxide is formed.

According to a second embodiment of the present invention, (a) induction melting by mixing silicon (Si) and a lithium source; And (b) supplying an oxidation source to the resultant induction melting, pre-doping lithium into SiO _x particles; Including, lithium oxide or/and lithium silicon in the step of pre-doping lithium to the SiO _x particles It provides a method of producing SiO _x particles in which an irreversible phase containing oxide is formed.

The present invention SiO _x particles; To the irreversible phase of the lithium secondary battery anode SiO _x particles material to the be formed on the SiO _x surface of the particles, mixed with the SiO _x particulate includes; and non-reverse phase containing lithium oxide and / or a lithium-silicon oxide to provide.

In the method of manufacturing SiO _x particles for a negative electrode material for lithium secondary batteries according to the present invention, an irreversible phase such as lithium oxide and lithium silicon oxide is formed in advance by pre-doping lithium by adding a lithium source to the induction melting method. There is an effect of increasing.

Since this irreversible phase is stable in air, there is no reduction in the life of the electrode, and long-term storage of the electrode is possible.

In addition to the above-described effects, specific effects of the present invention will be described together while describing specific details for carrying out the present invention.

1 is a conceptual diagram of lithium pre-doping proposed in the present invention.
2 is a flow chart of a method of manufacturing SiO _x particles for a negative electrode material of a lithium secondary battery according to the first embodiment of the present invention.
3 is a flow chart of a method of manufacturing SiO _x particles for a negative electrode material of a lithium secondary battery according to a second embodiment of the present invention.
Figure 4 is a SEM image of a non-doped SiO _x nanoparticles (a) and the lithium pre-doped SiO _x nanoparticles (b).
Figure 5 is an XRD analysis result that the SiO _x nanoparticles and a lithium pre-doped SiO _x nanoparticles undoped.
6 is a graph that shows the electrochemical characteristics of the SiO _x are not nanoparticles and a lithium pre-doped SiO _x nanoparticles.

The above-described objects, features, and advantages will be described later in detail with reference to the accompanying drawings, and accordingly, one of ordinary skill in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar elements.

Hereinafter, it means that an arbitrary component is disposed on the "top (or lower)" of the component or the "top (or lower)" of the component, the arbitrary component is arranged in contact with the top (or bottom) of the component. In addition, it may mean that other components may be interposed between the component and any component disposed on (or under) the component.

In addition, when a component is described as being "connected", "coupled" or "connected" to another component, the components may be directly connected or connected to each other, but other components are "interposed" between each component. It is to be understood that "or, each component may be "connected", "coupled" or "connected" through other components.

Hereinafter, SiO _x particles for lithium pre-doped lithium secondary battery negative electrode material according to some embodiments of the present invention and a method of manufacturing the same will be described.

In the present invention, lithium is added but not in the form of an unstable metal, but a method of adding a lithium source to molten silicon by using an induction melting method. Accordingly, the present invention provides a technology for producing SiO _{x (0<x<2)} particles for a negative electrode material of a lithium secondary battery having high initial reversible efficiency by forming an irreversible phase generated during initial charging and discharging in advance.

1 is a conceptual diagram of lithium pre-doping proposed in the present invention.

Referring to FIG. 1, an irreversible phase such as lithium oxide and lithium silicon oxide is formed in advance. In this case, since an irreversible phase that occurs during initial charging and discharging is created in advance, lithium is not sacrificed during the first charging and discharging. This is called Passive Pre-lithiation.

The irreversible phase is stable in air and does not cause a decrease in the life of the electrode. Therefore, since the SiO _x particles for the negative electrode material that have been passively pre-lithiated have excellent stability in air, long-term storage of the electrode is possible. In addition, the manufacturing method of SiO _x particles for the negative electrode material that has been passive pre-lithiation is simpler than the lithium metal manufacturing method of the active pre-lithiation method.

2 is a flow chart of a method of manufacturing SiO _x particles for a negative electrode material of a lithium secondary battery according to the first embodiment of the present invention. Referring to FIG. 2, the method of manufacturing SiO _x particles of the present invention includes the step of inducing melting silicon (Si) (S110) and pre-doping lithium to SiO _x particles by supplying a lithium source and an oxidation source to silicon in a molten state. It includes a step (S120).

First, crystalline silicon (Si) is induction melted.

The induction melting method proceeds in a crucible installed in the space part of the vacuum chamber. Looking at the structure of the crucible, an induction coil is wound on the outside of the crucible whose upper side is open. A power supply unit for supplying power to the induction coil is provided outside the vacuum chamber. When power is supplied to the induction coil, the crucible is heated by induction, and the raw material charged in the crucible is melted to form a molten metal, and is volatilized into a gaseous state containing particles.

By using such an induction melting method, when a raw material made of silicon is supplied to the crucible with an open upper side and power is supplied, the raw material is inductively melted to form silicon in a molten metal state.

Silicon has low electrical conductivity up to about 700°C, and indirect heating is initially performed by heat applied to the crucible, and at temperatures higher than 700°C, the electrical conductivity is rapidly increased, and thus electromagnetic induction melting is mainly performed. For this purpose, the induction melting is preferably performed at 1100 to 1700°C, and the surface temperature of the molten metal is maintained at 1100 to 1700°C.

The induction melting is carried out in an inert gas atmosphere. For example, induction melting proceeds while argon gas, nitrogen gas, or the like is supplied into the crucible.

Subsequently, a lithium source and an oxidation source are supplied to the molten silicon. The lithium source and the oxidation source may be supplied by a nozzle or a vibration feeder positioned above the crucible, but are not limited thereto.

In the process of supplying the lithium source and the oxidation source, lithium is pre-doped on the SiO _x particles while forming an irreversible phase including lithium oxide or/and lithium silicon oxide.

The lithium source is lithium metal, lithium oxide (Li ₂ O, LiO ₂ , Li ₂ O ₂ ), lithium hydroxide (LiOH), lithium carbonate (Li ₂ CO ₃ ), lithium silicate (Li ₂ SiO ₃ ), lithium silicate ( Li ₂ Si ₂ O ₅ ), lithium silicate (Li ₄ SiO ₄ ), and lithium chloride (LiCl) may be selected and supplied. And the lithium source may be supplied in a granulated powder state of 1 ~ 2mm.

It is preferable to supply 0.1 to 30% by weight/hr of a lithium source with respect to 100% by weight of the total of the silicon and lithium sources. When the content of the lithium source is less than 0.1% by weight/hr, it is difficult to sufficiently form an irreversible phase. Conversely, when the content of the lithium source exceeds 30% by weight/hr, there is a risk of ignition in the air due to active pre-lithiation, and oxidation during storage causes a rapid deterioration in performance.

In order to form SiO _x particles from the silicon in the molten metal state, an oxidation source must be continuously supplied. To this end, an oxidation source including at least one of carbon monoxide (CO) gas, carbon dioxide (CO ₂ ) gas, water (H ₂ O), O ₂ /Ar and O ₂ /N ₂ is supplied.

It is preferable to supply 1 to 30 vol% of the oxidation source with respect to the total 100 vol% of the oxidation source and the inert gas. When the flow rate of the oxidation source is less than 1 vol%, the oxidation source for the formation of SiO _x particles is insufficient, and thus it is difficult to manufacture SiO _x powder. When the flow rate of the oxidation source is higher than 30 vol%, there is a problem that the X value in SiO _{x (0<x<2)} becomes high, making it difficult to control the capacity.

In this way, in the process of supplying the lithium source and the oxidation source, lithium is pre-doped on the SiO _x particles. At this time, Li ₂ O, LiOH, Li ₂ CO ₃ on the SiO _x particle surface, An irreversible phase comprising at least one of Li ₂ SiO ₃ , Li ₂ Si ₂ O ₅ , and Li ₄ SiO ₄ is formed. Or SiO _x particles and mixed Li ₂ O, LiOH, Li ₂ CO ₃ , An irreversible phase including at least one of Li ₂ SiO ₃ , Li ₂ Si ₂ O ₅ and Li ₄ SiO ₄ is formed. Is formed in the nonreciprocal phase SiO _x surface of the particles, and at the same time may be mixed with SiO _x particles.

The prepared SiO _x particles include at least one of crystalline silicon (Si) and silicon oxide (SiO ₂ ). The size of the prepared particles is nano-sized and has a diameter of approximately 10 to 1000 nm.

In the first embodiment, silicon and lithium sources are independently introduced, but in the second embodiment, silicon and lithium sources are mixed and introduced.

3 is a flow chart of a method of manufacturing SiO _x particles for a negative electrode material of a lithium secondary battery according to a second embodiment of the present invention. 3, the method of manufacturing SiO _x particles of the present invention includes the steps of induction melting by mixing silicon (Si) and a lithium source (S210) and pre-doping lithium to the SiO _x particles by supplying an oxidation source ( S220).

First, silicon (Si) and lithium source are mixed together to induce melting.

It is preferable to mix 0.1 to 30% by weight of the lithium source with respect to the total 100% by weight of the silicon and lithium source. When the supply amount of the lithium source is lower than 0.1% by weight, it is difficult to sufficiently form the irreversible phase. On the contrary, if it is higher than 30% by weight, there is a risk of ignition in the air due to active pre-lithiation, and it is oxidized during storage, resulting in a rapid deterioration in performance.

Matters on the induction melting method are as described above in the first embodiment.

In order to form SiO _x particles from the silicon, an oxidation source must be continuously supplied. In the process of supplying the oxidation source, lithium is pre-doped on the SiO _x particles while forming an irreversible phase including lithium oxide or/and lithium silicon oxide.

To this end, an oxidation source including at least one of carbon monoxide (CO) gas, carbon dioxide (CO ₂ ) gas, water (H ₂ O), O ₂ /Ar and O ₂ /N ₂ is supplied. Details on the oxidation source are as described above in the first embodiment.

Thus, the _{Li 2 O, LiOH, Li 2} CO 3, Li 2 SiO 3, Li 2 Si 2 O 5 and Li ₄ SiO least one of _four kinds of the surface SiO _x particles in the process of the lithium pre-doped in SiO _x particles A containing irreversible phase is formed. Or SiO _x particles and mixed Li ₂ O, LiOH, Li ₂ CO ₃ , An irreversible phase including at least one of Li ₂ SiO ₃ , Li ₂ Si ₂ O ₅ and Li ₄ SiO ₄ is formed. Is formed in the nonreciprocal phase SiO _x surface of the particles, and at the same time may be mixed with SiO _x particles.

The prepared SiO _x particles include at least one of crystalline silicon (Si) and silicon oxide (SiO ₂ ). The size of the prepared particles is nano-sized and has a diameter of approximately 10 to 1000 nm.

As described above, the method for producing lithium-pre-doped SiO _x particles of the present invention proceeds with a process of adding a lithium source to the induction melting method. According to the method of manufacturing the lithium-pre-doped SiO _x particles, by forming an irreversible phase such as lithium oxide and lithium silicon oxide in advance, there is an effect of improving the initial charge and discharge efficiency by preventing the sacrifice of lithium in the initial charge and discharge. Furthermore, since the volume expansion of the negative electrode material of the lithium secondary battery can be suppressed and a negative electrode material for a lithium secondary battery having a high capacity can be manufactured, it is very effective in manufacturing a negative electrode material that can improve the properties of the material for energy storage.

In addition, the SiO _x particles pre-doped with lithium in the present invention can be applied as a negative electrode material for lithium secondary batteries that can be used in IT materials, electric vehicles, and the like.

A detailed example of the lithium-pre-doped SiO _x particles for a negative electrode material for lithium secondary batteries and a method of manufacturing the same will be described below.

Figure 4 is a SEM image of a non-doped SiO _x nanoparticles (a) and the lithium pre-doped SiO _x nanoparticles (b).

Referring to FIG. 4, it can be seen that lithium is pre-doped on SiO _x nanoparticles having a diameter of 1000 nm or less.

Figure 5 is an XRD analysis result that the SiO _x nanoparticles and a lithium pre-doped SiO _x nanoparticles undoped.

Referring to FIG. 5, Si, Li ₂ SiO ₃ , and Li ₄ SiO ₄ phases were generated in the lithium-pre-doped SiO _x nanoparticles according to the present invention. This indicates that the formed phase irreversible mixed in the SiO _x nanoparticle surfaces and / or SiO _x nanoparticles.

6 is a graph that shows the electrochemical characteristics of the SiO _x are not nanoparticles and a lithium pre-doped SiO _x nanoparticles.

-Lithium pre-doped SiO _x nanoparticles were prepared as follows.

An induction coil having a diameter of 8 mm was wound 10 times based on the upper part of the crucible. Si raw material was charged into this crucible. After that, an alternating current having a frequency of 6.7 kHz was applied to the induction coil. After maintaining the vacuum in the chamber at 5 to 10 torr for 1 hour or more, Ar gas was injected to form an operating vacuum of about 760 to 800 torr.

In order to induce melting of 100 g of silicon, the melting started from the center of the charged silicon by applying 30 to 60 kW power to the induction coil. After heating the molten metal to a surface temperature of 1400° C., lithium source (Li ₂ O) was injected as much as 5 wt%/hr and O ₂ /Ar gas was injected as much as 15 vol% to form lithium pre-doped particles.

The prepared SiO _x nanoparticles were collected, prepared in a slurry form with a binder and an active material, applied to a Cu-foil current collector, dried to prepare an electrode, and the prepared negative electrode was rolled and then a battery was manufactured to evaluate the electrochemical properties. I did.

-The prepared negative electrode was applied to a lithium secondary battery to measure the initial reversible efficiency (ICE, the ratio of the first discharge capacity to the first charging capacity).

A coin-type half-cell was manufactured using metallic lithium as a counter electrode of the negative electrode. As an electrolyte, ethyl carbonate and dimethyl carbonate were mixed in a volume ratio of 1: 1, fluoroethyl carbonate was included in 3% by weight, and 1 M of LiPF ₆ was dissolved.

-Charge/discharge test method: cut-off voltage 0.005~1.5v at 0.1 c-rate in the first cycle, cut-off voltage 0.005v~1v at 0.1 c-rate in the second cycle, 50th from the third to the last The cycle was charged and discharged with a cut-off voltage of 0.005 to 1v at 0.5 c-rate.

Referring to FIG. 6, a battery using lithium-pre-doped SiO _x nanoparticles has an initial reversible capacity of 500 to 600 mAh/g, and a high Coulomb efficiency (CE) of approximately 100%. In addition, referring to the table inserted in FIG. 6, the initial reversible efficiency (ICE) of the lithium-pre-doped SiO _x nanoparticles is 78.2%, and shows a relatively high initial reversible efficiency compared to the sample not pre-doped with lithium. It can be seen that the initial irreversible reaction was relatively reduced.

Accordingly, the method for producing lithium-pre-doped SiO _x nanoparticles according to the present invention has an effect of lowering initial irreversible efficiency and increasing initial reversible efficiency by forming an irreversible phase in advance.

[Table 1] is a table showing the initial reversible efficiency characteristics of a battery using SiOx particles pre-doped with lithium according to the present invention.

-Lithium pre-doped SiOx particles were prepared in the same manner as in the manufacturing method of FIG. 6 according to the conditions of the following [Table 1], but a lithium source was injected in the process of heating by controlling the surface temperature of the molten metal. Subsequently, an oxidation source was injected to form lithium pre-doped particles.

The prepared SiO _x nanoparticles were collected, prepared in a slurry form with a binder and an active material, applied to a Cu-foil current collector, dried to prepare an electrode, and the prepared negative electrode was rolled and then a battery was manufactured to evaluate the electrochemical properties. I did.

-The capacity retention rate was expressed as a percentage of the first discharge capacity compared to the last discharge capacity.

[Table 1]

When SiO _x particles are produced under the conditions of [Table 1], the initial reversible efficiency is mostly 60% or more. It can be seen that after 50 cycles, most of the samples have more than 70% capacity conserved.

Therefore, the manufacturing technology of SiO _x particles for a negative electrode material of a lithium secondary battery according to the present invention has an effect of increasing initial reversible efficiency by pre-doping lithium to form an irreversible phase such as lithium oxide and lithium silicon oxide. Since the irreversible phase is stable in air, there is no reduction in the life of the electrode, and long-term storage of the electrode is possible.

As described above with reference to the drawings illustrated for the present invention, the present invention is not limited by the embodiments and drawings disclosed in the present specification, and various by a person skilled in the art within the scope of the technical idea of the present invention. It is obvious that transformation can be made. In addition, even if not explicitly described and described the effects of the configuration of the present invention while describing the embodiments of the present invention, it is natural that the predictable effects of the configuration should also be recognized.

Claims (12)

(a) induction melting silicon (Si) to form molten silicon; And
(b) supplying a lithium source and an oxidation source to the silicon in the molten metal state, and pre-doping the SiO _x particles with lithium; Including,
Process for producing a SiO _x particles are non-reversible image is formed comprising a lithium oxide and / or silicon oxide lithium in the step of pre-doping of lithium to the SiO _x particles.
(a) mixing silicon (Si) and a lithium source to induce melting; And
(b) supplying an oxidation source to the induction-melted product, and pre-doping lithium into the SiO _x particles; including,
Process for producing a SiO _x particles are non-reversible image is formed comprising a lithium oxide and / or silicon oxide lithium in the step of pre-doping of lithium to the SiO _x particles.
The method according to claim 1 or 2,
The lithium source is lithium metal, lithium oxide (Li ₂ O, LiO ₂ , Li ₂ O ₂ ), lithium hydroxide (LiOH), lithium carbonate (Li ₂ CO ₃ ), lithium silicate (Li ₂ SiO ₃ ), lithium silicate ( Li ₂ Si ₂ O ₅ ), lithium silicate (Li ₄ SiO ₄ ), and a method of producing SiO _x particles comprising at least one of lithium chloride (LiCl).
The method of claim 1,
A method for producing SiO _x particles in which a lithium source is supplied at 0.1 to 30% by weight/hr based on 100% by weight of the silicon and lithium source.
The method of claim 2,
SiO _x particle production method of mixing 0.1 to 30% by weight of a lithium source with respect to the total 100% by weight of the silicon and lithium source.
The method according to claim 1 or 2,
The induction melting is carried out at 1100 ~ 1700 ℃ SiO _x method for producing particles.
◈ Claim 7 was abandoned upon payment of the set registration fee. The method according to claim 1 or 2,
The oxidation source is a method of producing SiO _x particles comprising at least one of carbon monoxide (CO) gas, carbon dioxide (CO ₂ ) gas, water (H ₂ O), O ₂ /Ar, and O ₂ /N ₂ .
The method according to claim 1 or 2,
SiO _x particle production method for supplying 1 to 30 vol% of the oxidation source with respect to the total 100 vol% of the oxidation source and the inert gas.
◈ Claim 9 was abandoned upon payment of the set registration fee. The method according to claim 1 or 2,
The lithium oxide or/and the irreversible phase containing lithium silicon oxide is a method for producing SiO _x particles comprising at least one of Li ₂ O, Li ₂ SiO ₃ , Li ₂ Si ₂ O ₅ and Li ₄ SiO ₄ .
SiO _x particles; And
Including; an irreversible phase containing lithium oxide or/and lithium silicon oxide,
Said nonreciprocal phase will be formed on the SiO _x surface of the particles, mixed with the SiO _x particulate,
The ratio of the lithium secondary battery anode as the initial reversible efficiency (ICE) based on the SiO _x material particles, the initial reversible efficiency (ICE) is a lithium secondary battery anode materials for SiO _x particles more than 20% does not include a reverse phase.
The method of claim 10,
The irreversible phase containing the lithium oxide or/and lithium silicon oxide is Li ₂ O, SiO _x particles for a negative electrode material for lithium secondary batteries containing at least one of Li ₂ SiO ₃ , Li ₂ Si ₂ O ₅ and Li ₄ SiO ₄ .
The method of claim 10,
The SiO _x particles of crystalline silicon (Si) and silicon oxide (SiO _{2) x} SiO lithium secondary battery negative electrode material particles containing at least one of.

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