KR101742854B1 - Anode active material for lithium secondary battery, preparation method thereof, and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to carbon-based cores; Metal oxide particles coated on the carbon-based core; And a carbon coating layer existing on the surfaces of the carbon-based core and the metal oxide particles, and a method of manufacturing the same.
The negative electrode active material according to an embodiment of the present invention can be used for a negative electrode of a lithium secondary battery to form a more stable SEI layer when it reacts with an electrolyte, thereby reducing the resistance and improving the output characteristics of the lithium secondary battery. .

Description

TECHNICAL FIELD [0001] The present invention relates to a negative electrode active material, a method for producing the same, and a lithium secondary battery comprising the same. BACKGROUND ART [0002]

The present invention relates to carbon-based cores; And a shell containing the metal oxide particles coated on the carbon-based core, and a method of manufacturing the same.

BACKGROUND ART [0002] With the recent development of the information communication industry, as electronic devices have become smaller, lighter, thinner, and portable, there is a growing demand for higher energy density of batteries used as power sources for such electronic devices. Lithium secondary batteries are the ones that can best meet this demand, and researches thereon are actively being carried out.

Various types of carbon-based materials including artificial graphite, natural graphite, or hard carbon capable of lithium insertion / removal have been applied to the anode active material of the lithium secondary battery. The carbon-based graphite provides advantages in terms of energy density of a lithium battery and is most widely used because it guarantees a long life of a lithium secondary battery with excellent reversibility.

However, graphite has a problem in that its capacity is low in terms of energy density per unit volume of electrodes, and a high side discharge voltage tends to cause a side reaction with the organic electrolytic solution to be used, and there is a risk of ignition or explosion due to malfunction or overcharge of the battery.

Therefore, it is urgently required to develop a negative electrode active material that can simultaneously satisfy safety and electrical characteristics of a secondary battery.

Disclosure of Invention Technical Problem [8] The present invention provides a negative electrode active material capable of improving the high-rate and output characteristics of a lithium secondary battery and improving safety, and a method of manufacturing the same.

In order to solve the above problems, the present invention provides a carbon-based core; And a shell containing metal oxide particles coated on the carbon-based core, wherein the metal oxide particles have an average particle diameter (D ₅₀ ) of 50 nm or less.

The present invention also provides a method of manufacturing a negative electrode active material, which comprises mechanically milling carbon-based particles and metal oxide particles of 50 nm or less to form a shell containing metal oxide particles on the carbon-based core do.

The present invention also provides a negative electrode comprising a current collector and the negative active material formed on at least one surface of the current collector.

Further, the present invention provides a lithium secondary battery comprising the positive electrode, the negative electrode, and the separator interposed between the positive electrode and the negative electrode using such a negative electrode.

The negative electrode active material according to an embodiment of the present invention can form a shell containing metal oxide particles on the carbon-based core to form a more stable SEI layer upon reaction with the electrolyte, thereby reducing the resistance, The performance of the secondary battery can be improved. In particular, by including metal oxide particles having an average particle diameter of 50 nm or less in the shell, the high-rate characteristics and the output characteristics of the lithium secondary battery can be further improved.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention and, together with the description of the invention, It should not be construed as limited.
1 is a schematic view of an anode active material according to an embodiment of the present invention.
2 is a graph showing the output characteristics of the lithium secondary batteries of Examples 1 and 2 according to the average particle diameter of the carbon-based core.
FIG. 3 is a graph illustrating the output characteristics of lithium secondary batteries of Example 1 and Comparative Example 1 according to presence or absence of a shell containing metal oxide particles. FIG.
4 is a graph showing the output characteristics of the lithium secondary batteries of Examples 1 and 3 according to the presence or absence of a pitch coating on the carbon-based core.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

The negative electrode active material of the present invention comprises a carbon-based core; And a shell comprising metal oxide particles coated on the carbon-based core, wherein the metal oxide particles have an average particle diameter (D ₅₀ ) of 50 nm or less.

The negative electrode active material according to an embodiment of the present invention can form a shell containing metal oxide particles on a carbon-based core to form a more stable SEI layer upon reaction with an electrolyte, thereby reducing resistance, The performance of the secondary battery can be improved. In particular, by including metal oxide particles having an average particle diameter of 50 nm or less in the shell, the high-rate characteristics and the output characteristics of the lithium secondary battery can be further improved.

The anode active material according to an embodiment of the present invention may be formed of a shell containing metal oxide particles on a carbon-based core.

According to an embodiment of the present invention, the carbon-based core may include a carbon-based material capable of intercalating and deintercalating lithium ions, and the carbon-based core may be natural graphite, artificial graphite, mesocarbon microbeads (MCMB), and carbon black.

The carbon-based material may have an average particle diameter (D ₅₀ ) of, for example, 5 탆 to 30 탆, preferably 5 탆 to 10 탆, and a specific surface area (BET) of 2.0 m 2 / g to 3.0 m 2 / have.

If the BET specific surface area of the carbon-based material is out of the above range, the output characteristics and initial efficiency of the secondary battery may be deteriorated and the remaining capacity may be decreased during storage at a high temperature.

According to an embodiment of the present invention, the carbon-based material may further include an amorphous carbon coating layer on the carbon-based material.

In the negative electrode active material according to an embodiment of the present invention, the metal oxide particles forming the shell may be formed of a metal that can form a coating (SEI (solid electrolyte interface) coating) having a better ionic conductivity than the carbon- Oxide particles. For example, any one selected from the group consisting of TiO ₂ , Al ₂ O ₃ , Cs ₂ O ₃ , ZnO, ZrO ₂ and Y ₂ O ₃ , or a mixed particle of two or more thereof.

The metal oxide particles may have an average particle diameter of 50 nm or less, preferably 10 nm to 50 nm, and the average particle diameter may improve the high rate characteristics. If the average particle diameter of the metal oxide is more than 50 nm, the diffusion path is prolonged in the process of inserting and desorbing lithium, and the high-rate characteristic and the output characteristic may be deteriorated due to the large resistance.

According to an embodiment of the present invention, it is most preferable that the metal oxide particles are synthesized so as to have an average particle diameter of 50 nm or less in the synthesis, and the metal oxide particles having an average particle diameter of several hundreds nm are subjected to milling treatment It can be implemented to have a particle diameter.

The milling process may be performed using a conventional milling apparatus, for example, a high energy ball mill, a planetary mill, a stirred ball mill, and a vibrating mill apparatus Can be used.

According to an embodiment of the present invention, the metal oxide particles may be contained in an amount of 5 wt% or less based on 100 wt% of the negative electrode active material.

According to an embodiment of the present invention, the surface of the carbon-based core can be sufficiently coated without leaving excess metal oxide particles in the above range, and the desired effect of the present invention can be exhibited very well.

If the content of the metal oxide particles exceeds the above range, the resistance between the active materials increases due to the presence of the metal oxide remaining in the coating on the carbon-based core, thereby deteriorating the electrochemical characteristics. When the metal oxide particles are less than the above range, the metal oxide particles can not be uniformly formed on the surface of the carbon-based core, and the effect of the output characteristics due to the formation of the desired safe film in the present invention may be insignificant.

The thickness ratio of the core to the shell according to an embodiment of the present invention may be, for example, 1: 0.1 to 0.2.

According to the anode active material according to an embodiment of the present invention, the initial efficiency can be improved by further including a carbon coating layer on the shell, thereby imparting additional conductivity and further reducing side reactions with the electrolyte solution.

The carbon coating layer may have a thickness of 10 nm to 50 nm.

The negative electrode active material according to an embodiment of the present invention may be formed by forming a shell containing metal oxide particles on a carbon-based core, thereby reducing the BET of the negative electrode active material to about 3% To 10% or more.

The specific surface area (BET) of the negative electrode active material according to an embodiment of the present invention may be 3.5 m 2 / g to 5.0 m 2 / g.

In the present invention, the specific surface area of the negative electrode active material or the carbon-based material can be measured by a BET (Brunauer-Emmett-Teller) method. For example, it can be measured by a BET 6-point method by a nitrogen gas adsorption / distribution method using a porosimetry analyzer (Bell Japan Inc, Belsorp-II mini).

In addition, the anode active material according to an embodiment of the present invention may further include a carbonaceous material.

The carbon material may include at least one selected from the group consisting of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), carbon fibers and carbon black.

The mixing ratio of the negative electrode active material and the carbon-based material may be 50 to 99 parts by weight: 1 to 50 parts by weight.

In addition, the present invention can provide a method for producing the negative electrode active material.

The method of manufacturing an anode active material according to an embodiment of the present invention includes mechanically milling a carbon-based material and metal oxide particles having an average particle diameter of 50 nm or less to form a shell containing metal oxide particles on the carbon-based core can do.

According to the method for manufacturing an anode active material according to an embodiment of the present invention, metal oxide particles are uniformly coated on a carbon-based core by a mechanical milling method to obtain a core-shell structure negative electrode active material.

Specifically, according to the method of manufacturing an anode active material according to an embodiment of the present invention, the carbon-based material and the metal oxide particles may be mechanically milled to form a shell containing metal oxide particles on the carbon-based core.

According to another embodiment of the present invention, there is provided a method of manufacturing a carbon-based material, which comprises coating a carbon-based material with an amorphous carbon coating layer, mechanically milling the carbon-based material and the metal oxide particles including the amorphous carbon coating layer, A shell containing particles can be formed.

At this time, the coating with the amorphous carbon coating layer can be carried out by a conventional method. For example, by mixing a carbon precursor such as a pitch or a hydrocarbon-based material with a carbon-based material, and then performing a heat treatment.

According to the method of manufacturing an anode active material according to an embodiment of the present invention, the mechanical milling is used to form a shell in which metal oxide particles are uniformly formed on the carbon-based core, and for example, A high energy ball mill, a planetary mill, a stirred ball mill, and a vibrating mill method may be used.

According to an embodiment of the present invention, the carbon-based material and the metal oxide particles are mechanically milled to uniformly coat the metal oxide particles on the surface of the carbon-based material as shown in the schematic view of the anode active material shown in FIG. 1 .

The use ratio of the carbon-based material and the metal oxide particles according to an embodiment of the present invention may be in the range of 1: 0.005 to 0.05 weight ratio.

According to the method of manufacturing an anode active material according to an embodiment of the present invention, a step of forming a carbon coating layer on the shell may be further included.

The carbon coating layer may be formed by mixing a negative electrode active material containing the core and the shell with a carbon precursor, followed by heat treatment.

The carbon precursor may be any of those which generate carbon by heat treatment. For example, a precursor similar to or the same as the carbon precursor used for forming the amorphous carbon coating layer may be used.

The carbon precursor may be used in an amount of 1 to 40% by weight based on the total weight of the negative electrode active material.

When the weight of the carbon precursor is less than 1 wt%, the total coating amount is insufficient to obtain a uniform coating. If the weight of the carbon precursor is more than 40 wt%, carbonized powder may aggregate.

For example, the carbon coating layer may be carbonized using the amorphous carbon precursor. The coating method can be used both dry and wet mixing. In addition, a vapor deposition method such as a chemical vapor deposition (CVD) method using a gas including carbon such as methane, ethane, propane, ethylene, acetylene, etc. may also be used.

In the method of manufacturing an anode active material according to an embodiment of the present invention, the heat treatment temperature for forming the carbon coating layer may be 160 ° C. to 1300 ° C., preferably 300 ° C. to 1100 ° C., and the heat treatment time is about 20 minutes To 20 hours, preferably from 30 minutes to 10 hours.

If the heat treatment temperature is lower than 160 ° C, the temperature is too low to form a carbon coating layer, and if it exceeds 1300 ° C, the temperature is too high to change the crystal structure of the target compound. In addition, the heat treatment is preferably performed in an inert atmosphere in which a nitrogen gas, an argon gas, a helium gas, a krypton gas, or a xenon gas is present.

The carbon coating layer formed as described above may be uniformly or uniformly coated on the carbon-based core and the metal oxide particles as a whole. The thickness of the coating layer is not particularly limited, but may be, for example, 10 nm to 50 nm.

If the thickness of the carbon coating layer is less than 10 nm, the effect of increasing the electric conductivity due to the carbon coating layer is insignificant, and the initial efficiency may be lowered due to high reactivity with the electrolyte when the anode active material is applied. When the thickness of the carbon coating layer is more than 50 nm, the thickness of the carbon coating layer is excessively increased, which may hinder the mobility of lithium ions and increase the resistance.

In addition, the average particle diameter (D ₅₀ ) of the negative electrode active material according to an embodiment of the present invention may be 5 μm to 50 μm, preferably 5 μm to 20 μm.

When the average particle diameter of the negative electrode active material is less than 5 탆, it may be difficult to disperse in the negative electrode active material slurry or the negative electrode active material in the electrode may aggregate. When the average particle diameter exceeds 50 탆, One reaction is difficult, so that the lifetime characteristics and the thickness expansion inhibition characteristics can be greatly reduced.

In the present invention, the average particle diameter of the particles can be defined as the particle diameter at the 50% of the particle diameter distribution of the particles. The average particle diameter (D ₅₀ ) of the particles according to an embodiment of the present invention can be measured using, for example, a laser diffraction method. The laser diffraction method generally enables measurement of a particle diameter of several millimeters from a submicron region, resulting in high reproducibility and high degradability.

In addition, according to an embodiment of the present invention, it is possible to further include a step of adding and mixing a carbon material to the negative electrode active material.

The carbon material may include at least one selected from the group consisting of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), carbon fibers and carbon black.

The mixing ratio of the anode active material and the carbonaceous material may be 50 to 99 parts by weight: 1 to 50 parts by weight.

In addition, the present invention may include a current collector and a negative electrode including the negative active material formed on at least one surface of the current collector.

According to an embodiment of the present invention, the cathode may be manufactured according to a manufacturing method commonly used in the art. In addition, the anode according to an embodiment of the present invention can be manufactured by a conventional method in the art as well as the cathode.

For example, a binder and a solvent may be mixed and stirred with a binder and a solvent, if necessary, with a conductive material and a dispersing agent to prepare a slurry, and the slurry may be applied to a current collector and compressed to produce an electrode.

Examples of the binder used in the present invention include polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile and polymethyl methacrylate (polymethylmethacrylate), and the like can be used.

As the cathode active material, a lithium-containing transition metal oxide may be preferably used. For example, Li _x CoO ₂ (0.5 <x <1.3), Li _x NiO ₂ (0.5 <x <1.3), Li _x MnO _{2 x <1.3), Li x Mn} 2 O 4 (0.5 <x <1.3), Li x (Ni a Co b Mn c) O 2 (0.5 <x <1.3, 0 <a <1, 0 <b <1, Li _x Co _{1- y} Mn _y O ₂ (where 0 <c <1, a + b + c = 1), Li _x Ni _1-y Co _y O ₂ 0.5 <x <1.3, 0≤y < 1), Li x Ni 1 -y Mn y O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn c) O 4 ( (0.5 <x <1.3, 0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), Li _x Mn _{2 -z} Ni _z O ₄ (0.5 <x <1.3, 0 <z <2), Li _x CoPO ₄ (0.5 <x <1.3) and Li _x FePO ₄ (0.5 <z <2), Li _x Mn _{2 -z} Co _z O ₄ x < 1.3), or a mixture of two or more thereof. The lithium-containing transition metal oxide may be coated with a metal such as aluminum (Al) or a metal oxide. In addition to the lithium-containing transition metal oxide, sulfide, selenide and halide may also be used.

When the electrode is manufactured, a lithium secondary battery having a separator and an electrolyte interposed between the positive electrode and the negative electrode, which is conventionally used in the art, can be manufactured using the electrode.

In the electrolyte used in the present invention, the lithium salt that may be included as the electrolyte may be any of those conventionally used in an electrolyte for a lithium secondary battery. For example, examples of the anion of the lithium salt include F ^- , Cl ^- , Br ^{- _{, I -, NO 3 -,}} N (CN) 2 -, BF 4 -, ClO 4 -, PF 6 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 _{^{PF 2 -, (CF 3)}} 5 PF -, (CF 3) 6 P -, CF 3 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, (FSO 2) 2 N _{^{-, CF 3 CF 2 (CF}} 3) 2 CO -, (CF 3 SO 2) 2 CH -, (SF 5) 3 C -, (CF 3 SO 2) 3 C -, CF 3 (CF 2) 7 SO ₃ ^- , CF ₃ CO ₂ ^- , CH ₃ CO ₂ ^- , SCN ^- and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- .

As the organic solvent contained in the electrolytic solution used in the present invention, the organic solvent commonly used in the electrolyte for a lithium secondary battery can be used without limitation, and examples thereof include propylene carbonate (PC), ethylene carbonate (ethylene carbonate) EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, dipropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxy Ethane, vinylene carbonate, sulfolane, gamma-butyrolactone, propylene sulfite, and tetrahydrofuran, or a mixture of two or more thereof. In particular, ethylene carbonate and propylene carbonate, which are cyclic carbonates in the carbonate-based organic solvent, can be preferably used because they have high permittivity as a high-viscosity organic solvent and dissociate the lithium salt in the electrolyte well. To such a cyclic carbonate, dimethyl carbonate and diethyl When a low viscosity, low dielectric constant linear carbonate such as carbonate is mixed in an appropriate ratio, an electrolyte having a high electric conductivity can be prepared, and thus it can be more preferably used.

Alternatively, the electrolytic solution stored in accordance with the present invention may further include an additive such as an overcharge inhibitor or the like contained in an ordinary electrolytic solution.

As the separator, a conventional porous polymer film conventionally used as a separator, for example, a polyolefin such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer and an ethylene / methacrylate copolymer A porous polymer film made of a high molecular weight polymer may be used alone or in a laminated manner, or a nonwoven fabric made of a conventional porous nonwoven fabric such as a glass fiber having a high melting point, a polyethylene terephthalate fiber or the like may be used. It is not.

The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be a cylindrical shape, a square shape, a pouch shape, a coin shape, or the like using a can.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Example

EXAMPLES The present invention will be further illustrated by the following examples and experimental examples, but the present invention is not limited by these examples and experimental examples.

&Lt; Production of lithium secondary battery >

Example  One

&Lt; Preparation of negative electrode active material &

Pitch-coated natural graphite having a particle size of about 8 탆 and TiO ₂ powder of about 50 nm pulverized by a milling apparatus The particles were mechanically coated using a ball mill to form TiO ₂ The particles were uniformly coated to form a shell on the core.

The coated particles were wet-coated on an ethanol (6 wt% pitch-ethanol solution) diluted with coal-based pitch and then heat-treated at about 400 ° C in an argon atmosphere to form an anode active material containing a carbon coating layer on the shell .

Natural graphite and TiO ₂ The weight ratio was 98 wt%: 2 wt%, and the carbon coating layer was about 20 nm.

&Lt; Production of lithium secondary battery >

Negative electrode active material, SBR (styrene-butadiene rubber), thickening agents as (carboxy methyl cellulose), acetylene black as a and the conductive material 95 CMC as a binder: 2: 2: 1 of water (H ₂ O), and these solvents mixed in a weight ratio of To prepare a uniform negative electrode slurry. The prepared negative electrode slurry was coated on one side of the copper current collector to a thickness of 65 μm, dried and rolled, and then punched to a required size to prepare a negative electrode.

Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 30:70, and LiPF ₆ was added to the non-aqueous electrolyte solvent to prepare a 1 M LiPF ₆ non-aqueous electrolyte.

In addition, a lithium metal foil was used as a counter electrode, that is, an anode. A polyolefin separator was interposed between both electrodes, and then the electrolyte was injected to prepare a coin-type lithium secondary battery.

Example  2

A negative electrode active material and a lithium secondary battery were prepared in the same manner as in Example 1, except that pitch-coated natural graphite having a particle size of about 8 탆 was used instead of pitch-coated natural graphite having a particle size of about 8 탆. In the negative electrode active material, the weight ratio of natural graphite and TiO ₂ was 98 wt%: 2 wt%. The carbon coating layer was about 20 nm.

Example  3

A negative electrode active material and a lithium secondary battery were prepared in the same manner as in Example 1, except that natural graphite without pitch coating was used instead of pitch-coated natural graphite having a particle size of about 8 탆. In the negative electrode active material, natural graphite and TiO ₂ The weight ratio was 98 wt%: 2 wt%. The carbon coating layer was about 20 nm.

Comparative Example  One

The 50 nm TiO ₂ A negative electrode active material and a lithium secondary battery were produced in the same manner as in Example 1, except that particles were not used but only natural graphite was used.

Experimental Example  One

<Measurement of output characteristics>

The lithium secondary batteries of Examples 1 to 3 and Comparative Example 1 were continuously discharged at -30 캜.

The battery was charged at a constant current (CC) of 4.2 V at room temperature with a lithium secondary battery (battery capacity 11 mAh), and then charged at a constant voltage (CV) of 4.2 V until the charge current reached 0.03 mAh. . Thereafter, the battery was discharged at a constant current (CC) of 2 C until SOC 50, stored at -30 ° C for 3 hours, discharged at 5 C for 6 seconds, left for 5 seconds, and left three times.

2 is a graph showing the output characteristics of the lithium secondary batteries of Examples 1 and 2 according to the average particle diameter of the carbon-based core.

3 is a graph showing the output characteristics of the lithium secondary batteries of Example 1 and Comparative Example 1 according to presence or absence of a shell containing metal oxide particles.

4 is a graph showing the output characteristics of the lithium secondary batteries of Examples 1 and 3 according to the presence or absence of a pitch coating layer (amorphous carbon coating layer) on the carbonaceous material.

Referring to FIG. 2, it can be seen that the size of the natural graphite particles affects the output characteristics.

Specifically, as in Example 1, when the size of the natural graphite particles is 8 탆, the coating effect of the metal oxide particles is more excellent than that of the natural graphite particles having the size of 11 탆 as in Example 2.

That is, as can be seen from the graph of FIG. 2, in the lithium secondary battery of Example 1 of the present invention, the voltage did not decrease while the current of 6C was flowing, while in Example 2, .

It can be seen from FIG. 2 that when the size of the natural graphite particles is small, the coating effect of the metal oxide particles is more prominent.

In the case of FIG. 3, as in Comparative Example 1, the negative electrode active material containing no metal oxide particles but using only natural graphite shows significantly reduced output characteristics as compared with Example 1. FIG.

As a result of comparing the output characteristics of the lithium secondary batteries of Examples 1 and 3 with and without the pitch coating layer (amorphous carbon coating layer) on the carbon-based material as shown in FIG. 4, In the case of an anode active material coated with a graphite oxide, the voltage drop is very large during the current of 6 C, which indicates that the resistance reduction effect expected by the metal oxide coating is not significant.

On the contrary, in the case of Example 1 in which a metal oxide is coated after the formation of a pitch coating layer on the carbon-based material, the resistance reduction effect is very large and the output characteristics are remarkably improved.

Therefore, it can be seen that the resistance and the output characteristics are affected by the existence of the pitch coating layer on the carbon-based material.

Claims (24)

A carbon-based core in which an amorphous carbon layer is formed;
A shell coated on the carbon-based core, the shell comprising metal oxide particles; And
And a carbon coating layer formed on the shell,
Wherein the carbon-based core comprises at least one carbon-based material selected from the group consisting of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), and carbon black,
Wherein the metal oxide particles have an average particle diameter (D50) of 50 nm or less.
delete The method according to claim 1,
Wherein the carbon-based core has an average particle diameter of 5 占 퐉 to 30 占 퐉 and a specific surface area (BET) of 2.0 m 2 / g to 3.0 m 2 / g.
delete The method according to claim 1,
Wherein the metal oxide particles are contained in an amount of 5 wt% or less based on 100 wt% of the negative electrode active material.
The method according to claim 1,
Wherein the metal oxide particle is any one selected from the group consisting of TiO ₂ , Al ₂ O ₃ , Cs ₂ O ₃ , ZnO, ZrO ₂ and Y ₂ O ₃ , or a mixture of two or more thereof.
delete The method according to claim 1,
Wherein the carbon coating layer has a thickness of 10 nm to 50 nm.
The method according to claim 1,
Wherein the negative electrode active material further comprises a carbonaceous material.
The method according to claim 1,
Wherein the negative electrode active material has a specific surface area (BET) of 3.5 m 2 / g to 5.0 m 2 / g.
Mechanically milling the carbon-based material and metal oxide particles of 50 nm or less to form a shell comprising metal oxide particles on the carbon-based core; And
And forming a carbon coating layer on the shell, the method comprising the steps of:
The method of claim 1, wherein the carbon-based core comprises at least one carbon-based material selected from the group consisting of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), and carbon black.
12. The method of claim 11,
Wherein the mechanical milling is selected from a high energy ball mill, a planetary mill, a stirred ball mill, and a vibrating mill method.
12. The method of claim 11,
Wherein the metal oxide particles are selected from the group consisting of TiO ₂ , Al ₂ O ₃ , Cs ₂ O ₃ , ZnO, ZrO ₂ and Y ₂ O ₃ , or a mixture of two or more thereof. Gt;
delete 12. The method of claim 11,
Wherein the use ratio of the carbon-based material: metal oxide particles is 1: 0.005 to 0.05 weight ratio.
delete 12. The method of claim 11,
Wherein the carbon coating layer is formed by mixing an anode active material containing the core and the shell with a carbon precursor and then heat-treating the carbon precursor.
18. The method of claim 17,
Wherein the carbon precursor is a pitch or a hydrocarbon-based material.

18. The method of claim 17,
Wherein the heat treatment is performed in a temperature range of 160 ° C to 1300 ° C.
12. The method of claim 11,
Further comprising adding a carbon material to the negative electrode active material and mixing the negative active material.
21. The method of claim 20,
Wherein the carbon material comprises at least one selected from the group consisting of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), carbon fibers, and carbon black.
21. The method of claim 20,
Wherein the mixing ratio of the negative electrode active material and the carbonaceous material is 50 to 99 parts by weight: 1 to 50 parts by weight.
A negative electrode comprising the current collector and the negative active material of claim 1 formed on at least one side of the current collector.
A positive electrode, a negative electrode of claim 23, and a separator interposed between the positive electrode and the negative electrode.

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