KR20160139143A - Positive electrode active material precursor and method for manufacturing the same, positive electrode active material manufactured by using the same - Google Patents

Abstract

The present invention relates to a positive electrode active material precursor and a positive electrode active material manufactured by using the same. The positive electrode active material has a pore part which is an empty space between the inside and the outside while the inside and the outside are filled. According to the present invention, the positive electrode active material has large surface area and is structurally stable, so when manufacturing a positive electrode with the positive electrode active material, the positive electrode having high durability and density can be provided.

Description

FIELD OF THE INVENTION The present invention relates to a positive electrode active material precursor, a method for producing the same, and a positive electrode active material prepared using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a positive electrode active material precursor,

The present invention relates to a precursor used for producing a cathode active material and a method for producing the precursor.

In the lithium secondary battery, lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ) and lithium composite metal oxide (for example, LiNi _1-x Co _x O ₂ (0 <x <1) , Li (Ni-Co-Mn) O ₂ , and Li (Ni-Co-Al) O ₂ . However, the lithium secondary battery including the anode made of such oxides has a low power output and is limited in application to electric bicycles and electric vehicles requiring high output.

Accordingly, in order to improve the output characteristics of the lithium secondary battery, a technique of using a cathode active material having an empty hollow structure in the production of an anode has been proposed (see Patent Literature). The cathode active material having a hollow structure has a wider surface area than a cathode active material having a generally dense structure, and thus has a large contact area with the electrolyte solution. As a result, the movement of lithium ions becomes smooth, and as a result, the output characteristics of the lithium secondary battery can be improved. In addition, as the charge / discharge cycle is repeated, the cathode active material undergoes a volume change and its shape is deformed. Such deformation acts as a factor to lower the lifetime of the lithium secondary battery. The cathode active material having the hollow structure is relatively Deformation can be suppressed and the lifetime characteristics of the lithium secondary battery can be improved.

However, since the cathode active material having a hollow structure has a hollow interior, there is a limit to increase the durability and density of the anode because the hollow structure is likely to collapse during the rolling process in the anode manufacturing process. As a result, It acts as a limiting factor in height.

Therefore, development of a cathode active material capable of increasing the durability and density of the anode while having a wide surface area is required.

Korean Patent Laid-Open Publication No. 2013-0000138

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a cathode active material precursor capable of enlarging the surface area of a cathode active material and a method for manufacturing the same.

Another object of the present invention is to provide a cathode active material capable of increasing the durability and density of the anode and a method for producing the same.

Another object of the present invention is to provide a positive electrode having high durability and high density while improving the output characteristics of a lithium secondary battery.

According to an aspect of the present invention, there is provided a semiconductor device comprising: a core layer; An oxide layer provided on the core layer; And a surface layer provided on the oxide layer.

Further, the present invention provides a method for producing a metal hydroxide, comprising the steps of: a) introducing a metal hydroxide into an aqueous solution mixed with an aqueous sodium hydroxide solution and an aqueous ammonia solution to form a core layer in an inert atmosphere; b) forming an oxide layer on the surface of the core layer; And c) forming a surface layer having the same composition as that of the core layer on the surface of the oxide layer.

According to another aspect of the present invention, A surface portion spaced apart from the core portion; At least one bridge portion connecting the core portion and the surface portion; And at least one pore portion existing between the core portion and the surface portion.

The present invention also provides a method for producing a cathode active material, comprising the steps of: A) preparing a cathode active material precursor prepared by the above production method; B) mixing the cathode active material precursor with a lithium precursor to prepare a mixed precursor; And C) heat-treating the mixed precursor.

The present invention also provides a lithium secondary battery including the positive electrode and the positive electrode prepared using the positive electrode active material.

The positive electrode active material of the present invention is structurally stable while having a large surface area because the core portion inside and the outside surface portion are filled and the core portion and the surface portion are empty (that is, the pore portion exists). Therefore, when a positive electrode is manufactured using the positive electrode active material of the present invention, it is possible to provide a positive electrode having high durability and high density. By applying such a positive electrode to a lithium secondary battery, a lithium secondary battery having high output and long life can be provided.

1 is a cross-sectional view illustrating a cathode active material precursor according to an embodiment of the present invention.
2 is a cross-sectional view illustrating a cathode active material according to an embodiment of the present invention.
3 is a cross-sectional image of the cathode active material precursor prepared in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention.
4 is a cross-sectional image of the cathode active material prepared in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention.
5 is a reference diagram for explaining Experimental Example 2 of the present invention.
6 to 8 are reference views for explaining Experimental Example 4 of the present invention.

Hereinafter, the present invention will be described.

The present invention provides a positive electrode active material which is formed by artificially forming an oxide layer on a positive electrode active material precursor, preparing a positive electrode active material by using the same, and having a pore between the inside and the outside, Specifically, it is as follows. Here, the cathode active material precursor of the present invention is described based on one particle, and the cathode active material of the present invention is described based on one cathode active material precursor particle.

1. Cathode active material precursor

Referring to FIG. 1, the cathode active material precursor of the present invention includes a core layer 11, an oxide layer 12, and a surface layer 13.

The core layer 11 included in the cathode active material precursor of the present invention is the center portion of the cathode active material precursor. The material forming the core layer 11 is not particularly limited, but is a metal hydroxide containing at least one selected from the group consisting of nickel (Ni), cobalt (Co) and manganese (Mn). The thickness (T ₁ ) (diameter) of the core layer 11 is not particularly limited. However, considering the structural stability of the cathode active material, it is preferable that the thickness is 1/2 to 4/5 of the cathode active material thickness Do.

The oxide layer (12) included in the positive electrode active material precursor of the present invention is provided on the core layer (11). The material forming the oxide layer 12 is not particularly limited, but may be made of a metal oxide alone, or a mixture of a metal oxide and a metal hydroxide. Here, the metal contained in the metal oxide and the metal hydroxide is not particularly limited, but may be a metal including at least one selected from the group consisting of nickel (Ni), cobalt (Co) and manganese (Mn). The thickness (T ₂ ) of the oxide layer 12 is not particularly limited, but is preferably 0.5 to 1.5 탆 in consideration of the surface area, structural stability, and density of the cathode active material.

The surface layer 13 included in the cathode active material precursor of the present invention is provided on the oxide layer 12. The material forming the surface layer 13 is the same metal hydroxide as the core layer 11. The thickness (T ₃ ) of the surface layer 13 is not particularly limited. However, in consideration of the structural stability and the density of the cathode active material, the thickness is preferably 2 to 5 탆.

Meanwhile, the density of the oxide layer 12 included in the cathode active material precursor of the present invention is lower than that of the core layer 11 and the surface layer 13, so that the cathode active material of the present invention is filled in and out, And a pore portion which is an empty space between the outside and the outside. That is, the internal density of the oxide layer 12 of the present invention is lower than the internal densities of the core layer 11 and the surface layer 13. When the cathode active material precursor of the present invention having such a density difference is heat- The oxide layer 12 having a relatively low density is converted into a pore portion which is an empty space that the rearrangement ratio of metal atoms by the heat treatment is reduced (that is, the number of metal atoms to be rearranged is small).

The internal density of the oxide layer 12 is lower than the internal densities of the core layer 11 and the surface layer 13 and the density difference is also present in the oxide layer 12. This causes the cathode active material of the present invention, And at least one bridge portion connecting the surface portions. That is, the oxide layer 12 has a low internal density portion X and a high internal density portion Y. When the cathode active material of the present invention is manufactured by heat treatment, the low internal density portion X is a metal The rearrangement ratio of the atoms is lowered to a pore portion which is an empty space and the portion Y having a relatively higher internal density than the portion X having a lower internal density has a higher rearrangement ratio of metal atoms and is converted into a bridge portion.

2. Manufacturing Method of Cathode Active Material Precursor

The present invention provides a method for producing the above-described cathode active material precursor, which will be described in detail as follows.

a) Formation of core layer 11

The metal hydroxide is added to an aqueous solution containing an aqueous sodium hydroxide solution and an aqueous ammonia solution to form the core layer 11. Specifically, a metal hydroxide is added to an aqueous solution containing an aqueous sodium hydroxide solution as a precipitant and an ammonia aqueous solution as a complexing agent, and a coprecipitation reaction is carried out to form a core layer 11 (nuclear particles) composed of a metal hydroxide.

The metal hydroxide is not particularly limited, but is preferably selected from the group consisting of nickel sulfate hydrate (NiSO ₄ .6H ₂ O), manganese sulfate hydrate (MnSO ₄ .H ₂ O) and cobalt sulfate hydrate (CoSO ₄ .7H ₂ O) It can be more than a species. The metal hydroxide is preferably added to a solvent (for example, water or ion-exchanged water) to prepare a metal aqueous solution so that the coprecipitation reaction can be performed well, and then the metal hydroxide is added to an aqueous solution containing an aqueous sodium hydroxide solution and an aqueous ammonia solution. At this time, the concentration of the metal contained in the metal aqueous solution may be in the range of 1.5 to 2.5 M.

Meanwhile, in order to prevent the oxidation of the core layer 11, the core layer 11 is preferably formed in an inert atmosphere, and the inner pH of the co-precipitation reaction is maintained at 11.0 to 12.0 so that the core layer 11 can be formed well. . The temperature and rotation speed of the reactor used for forming the core layer 11 are not particularly limited, but the temperature is preferably 30 to 50 ° C and the rotation speed is preferably 300 to 700 rpm.

b) Formation of oxide layer (12)

An oxide layer 12 is formed on the surface of the core layer 11 formed as described above. The method of forming the oxide layer 12 on the surface of the core layer 11 is not particularly limited, but the core layer 11 may be exposed to an atmosphere having an oxygen concentration of 400 to 1000 ppm or treated with an oxidizing agent to form the oxide layer 12 . Specifically, after the core layer 11 is formed in an inert atmosphere, oxygen is injected at a concentration of 400 to 1000 ppm together with an inert gas (for example, nitrogen, helium or argon) or an aqueous solution of an aqueous sodium hydroxide solution and an aqueous ammonia solution An oxidizing agent (for example, hydrogen peroxide) is added to form the oxidized layer 12.

The thickness of the oxide layer 12 can be controlled according to the time of exposure to an atmosphere having an oxygen concentration of 400 to 1000 ppm and the amount of the oxidizer added. Specifically, the time for exposing the core layer 11 to an atmosphere having an oxygen concentration of 400 to 1000 ppm is not particularly limited, but is preferably 1 to 4 hours. The amount of the oxidizing agent to be added for forming the oxide layer 12 is not particularly limited, but is preferably 1 to 2% by volume based on 100% by volume of the reactor .

c) Formation of the surface layer 13

A surface layer 13 having the same composition as that of the core layer 11 is formed on the surface of the oxide layer 12 formed as described above. The method of forming the surface layer 13 is the same as the method of forming the core layer 11. Specifically, the injection of oxygen implanted together with the inert gas is interrupted to form the oxide layer 12, and the surface layer 13 is formed on the surface of the oxide layer 12 by continuing the coprecipitation reaction. In addition, the oxidant injected for forming the oxide layer 12 is consumed in the process of forming the oxide layer 12, and then the surface layer 13 is formed on the surface of the oxide layer 12 as the coprecipitation reaction proceeds continuously.

3. Cathode active material

2, the cathode active material of the present invention includes a core portion 21, a surface portion 22, a bridge portion 23, and a pore portion 24.

The core portion 21 included in the positive electrode active material of the present invention is the inside of the positive electrode active material. The material forming the core portion 21 is not particularly limited and may be a composite oxide in which a metal oxide including at least one selected from the group consisting of nickel (Ni), cobalt (Co), and manganese (Mn) Lt; / RTI &gt;

The surface portion 22 included in the positive electrode active material of the present invention is spaced apart from the core portion 21 to the outside of the positive electrode active material. The distance D between the core portion 21 and the surface portion 22 (the thickness of the pore portion 24) (D) is not particularly limited. However, considering the surface area, structural stability, and density of the cathode active material, . The material forming the surface portion 22 is the same as the material forming the core portion 21.

The bridge portion 23 included in the cathode active material of the present invention connects the core portion 21 and the surface portion 22. One or more of the bridge portions 23 are formed of the same material as the core 21.

At least one pore portion 24 included in the cathode active material of the present invention exists between the core portion 21 and the surface portion 22. The shape of the pore portion 24 is not particularly limited, but it is preferable to have a cut ring shape as shown in Fig.

In the cathode active material of the present invention, since the pore portion 24 exists between the core portion 21 and the surface portion 22 and the core portion 21, which is an inner portion of the core portion 21, And is structurally stable as compared with the positive electrode active material of the hollow structure (that is, the core portion 21 of the present invention is not present). Therefore, when a positive electrode is manufactured using the positive electrode active material of the present invention, it is possible to provide a positive electrode material having excellent density and durability. By applying such a positive electrode material to a lithium secondary battery, a lithium secondary battery having excellent output characteristics and life characteristics can be provided.

4. Manufacturing method of cathode active material

The present invention provides a method for producing the above-described cathode active material, which will be described in detail as follows.

A) Preparation of cathode active material precursor

First, a cathode active material precursor is prepared. Here, the method of preparing the cathode active material precursor is described in the above '2. Method for preparing a cathode active material precursor &quot;

B) Preparation of mixed precursor

The prepared precursor of the cathode active material and the lithium precursor are mixed to prepare a mixed precursor. The material used in the lithium precursor is not particularly limited, and lithium hydroxide (LiOH), lithium nitrate (LiNO _3), lithium carbonate (Li ₂ CO _3), lithium sulfate (Li ₂ SO _4), and acetic acid lithium (LiCH ₃ CO ₂ ). &Lt; / RTI &gt;

C) Heat treatment

The mixed precursor is thermally treated to prepare a cathode active material including a core portion 21, a surface portion 22, a bridge portion 23, and a pore portion 24. Specifically, as described above, the cathode active material precursor including the core layer 11, the oxide layer 12, and the surface layer 13 has a different density of each layer. The present invention is to produce a cathode active material comprising a core portion 21, a surface portion 22, a bridge portion 23, and a pore portion 24 by heat treating the cathode active material precursor. At this time, a portion having a relatively high density also exists in the oxide layer 12 of the positive electrode active material precursor, and the positive electrode active material of the present invention includes the bridge portion 23 by this portion.

The conditions for the heat treatment of the mixture are not particularly limited, but the heat treatment temperature is preferably 800 to 950 ° C and the heat treatment time is preferably 5 to 24 hours.

5. Bipolar and lithium secondary batteries

The present invention provides a positive electrode and a lithium secondary battery comprising the positive electrode active material as described above, which will be described in detail below.

The positive electrode of the present invention is manufactured by materials and methods known in the art, except that the positive electrode active material described above is used.

The lithium secondary battery of the present invention comprises a positive electrode; cathode; Separation membrane; And a nonaqueous electrolyte. Such a lithium secondary battery of the present invention is manufactured by materials and methods known in the art, except that it includes the above-described anode. The lithium secondary battery of the present invention can be applied to various fields, but it is preferably applied to middle and large-sized electronic devices (for example, electric bicycle or electric vehicle) which require high output and long life.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[Example 1]

1) Preparation of cathode active material precursor

Sulfuric acid mol ratio of nickel, cobalt and manganese so that the nickel hydroxide 60:20:20 _{(NiSO 4 · 6H 2 O)} , cobalt hydroxide sulfate (CoSO ₄ · 7H ₂ O), and sulfate of manganese hydroxide (MnSO ₄ · H ₂ O ) Was dissolved in ion-exchanged water to prepare a 2.4 M aqueous metal solution. 35L coprecipitation reactor, a coprecipitation reaction was carried out in a nitrogen atmosphere while a 9% ammonia aqueous solution and the metal aqueous solution were injected at a constant rate to form a core layer. The temperature and the rotation speed of the coprecipitation reactor were set to 50 ° C and 400 rpm, respectively. In addition, 25% sodium hydroxide aqueous solution was injected so that the pH was maintained at 11.0 to 12.0.

When the diameter of the formed core layer was 5 占 퐉, a nitrogen atmosphere containing 600 ppm of oxygen was maintained for 1 hour to form an oxide layer.

Then, the coprecipitation reaction was conducted again under a nitrogen atmosphere containing no oxygen to obtain a precipitate having a surface layer formed thereon. The resulting precipitate was recovered and washed with a centrifugal filter at a temperature of 40 to 50 ° C. until the pH of the filtrate was 9.0 or less and then dried at 150 ° C. for 24 hours to obtain a cathode active material precursor having a diameter of 10 μm (Composition: [Ni _0.6 Mn _0.2 Co _0.2 ] (OH) ₂ ).

2) Manufacture of cathode active material

The cathode active material precursor prepared above and lithium hydroxide (LiOH) were mixed at a molar ratio of 1: 1 and then heat-treated at a temperature rising rate of 2 ° C / min at a temperature of 840 to 880 ° C for 8 to 12 hours in an air atmosphere, .

[Example 2]

A cathode active material was prepared in the same manner as in Example 1, except that a nitrogen atmosphere containing 600 ppm of oxygen was maintained for 2 hours to form an oxide layer.

[Example 3]

A cathode active material was prepared in the same manner as in Example 1, except that the oxidized layer was formed by maintaining a nitrogen atmosphere containing 600 ppm of oxygen for 1 hour when the formed core layer had a diameter of 7 탆.

[Example 4]

A cathode active material was prepared in the same manner as in Example 1, except that the oxide layer was formed by maintaining the nitrogen atmosphere containing 600 ppm of oxygen for 2 hours when the formed core layer had a diameter of 7 탆.

[Example 5]

The cathode active material was prepared in the same manner as in Example 1, except that the oxidized layer was formed by maintaining a nitrogen atmosphere containing 600 ppm of oxygen for 4 hours when the diameter of the formed core layer was 7 탆.

[Example 6]

A cathode active material was prepared in the same manner as in Example 1, except that a 34.5% hydrogen peroxide solution was added in an amount of 1 volume% based on the total volume of the reactor when the diameter of the formed core layer was 7 占 퐉.

[Comparative Example 1]

A cathode active material was prepared in the same manner as in Example 1, except that a cathode active material precursor (not forming an oxide layer) was produced only in a nitrogen atmosphere without maintaining a nitrogen atmosphere containing 600 ppm of oxygen for 1 hour.

[Comparative Example 2]

A cathode active material was prepared in the same manner as in Comparative Example 1, except that a cathode active material precursor was prepared by applying an oxygen atmosphere instead of a nitrogen atmosphere.

[Experimental Example 1] Cross section confirmation

Sections of each of the cathode active material precursors and cathode active materials prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were confirmed by scanning electron microscopy and the results are shown in FIG. 3 and FIG.

Referring to FIG. 3, the cathode active material precursors of Examples 1 and 2 according to the present invention had an annular metal oxide layer, but it was confirmed that no metal oxide layer existed in the cathode active material precursors of Comparative Examples 1 and 2 have.

Referring to FIG. 4, it can be seen that there are pores in the cathode active materials of Examples 1 and 2 according to the present invention, but no pores are present in the cathode active materials of Comparative Examples 1 and 2 (that is, 2 is a dense-structured cathode active material filled in the inside).

[Experimental Example 2] XRD analysis

The XRD of the cathode active material prepared in Example 1 and Comparative Example 1 was analyzed by methods known in the art, and the results are shown in FIG.

Referring to FIG. 5, it can be seen that the XRD analysis results of the cathode active material of Example 1 and the cathode active material of Comparative Example 1 are the same. This supports the fact that even when the oxide layer is formed in the production of the cathode active material precursor, the crystal structure of the cathode active material produced is not affected.

[Experimental Example 3] Density measurement

The tap density and the pellet density of the cathode active material precursor and the cathode active material prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were measured by the following methods and the results are shown in Table 1 Respectively.

1. Tap density (g / cc): Density measurement after injection of 50 g of cathode active material precursor, 100 g of cathode active material and 1000 times of tap using a 100 ml measuring cylinder

2. Pellet density (g / cc): 2 g of the positive electrode active material precursor and 3 g of the positive electrode active material are injected into the pellet mold.

division Cathode active material precursor Cathode active material Tap density
(g / cc) Pellet density
(g / cc) Tap density
(g / cc) Pellet density
(g / cc) Example 1 2.00 2.45 2.29 3.14 Example 2 1.76 2.36 2.12 3.08 Example 3 1.90 2.33 2.24 3.20 Example 4 1.73 2.33 2.15 3.21 Example 5 1.73 2.28 2.13 3.10 Example 6 1.77 2.33 2.17 3.21 Comparative Example 1 2.02 2.40 2.62 3.04 Comparative Example 2 1.35 1.87 1.70 2.45

Referring to Table 1, the tap density and the pellet density of the cathode active material precursor of the present invention tend to decrease as the time for injecting oxygen-containing gas is longer. However, the cathode active material of the present invention, It is possible to confirm that the pellet density is higher than that of the cathode active materials of Comparative Examples 1 and 2.

As described above, the positive electrode active material of the present invention has a pore portion between the inside and the outside and has a high packing density, so that it is possible to produce a positive electrode having a high density even when rolled at a low pressure and to minimize particle breakage of the positive electrode active material .

[Production Example 1]

The cathode active material prepared in Example 1, carbon black as a conductive material, and PVDF as a binder were mixed in a weight ratio of 92: 5: 3 and then NMP was added thereto to prepare a slurry-like mixture. The prepared mixture was deposited on aluminum foil at 60 to 80 탆 and dried at 80 캜 for 12 hours to prepare a positive electrode.

Coin cell type lithium secondary battery of 2032 standard was manufactured by the produced anode.

[Comparative Production Example 1]

A lithium secondary battery was prepared in the same manner as in Production Example 1, except that the cathode active material prepared in Comparative Example 1 was used instead of the cathode active material prepared in Example 1.

[Experimental Example 4] Evaluation of cell performance

The lithium secondary battery manufactured in Production Example 1 and Comparative Production Example 1 was left at 25 占 폚 for 10 hours, and after the open circuit voltage OCV was stabilized, the initial charge of 3.0 to 4.3 V at a cut- The discharge and the life evaluation were carried out (the capacity at 1 C was 170 mAh / g), and the results are shown in FIGS. 6 to 8 and Table 2.

1 ^st discharge capacity
(0.1 C, mAh / g) 1 ^st reversible efficiency
(%) Life characteristics
(50 cycles,%) Production Example 1 182.10 91.69 93.73 Comparative Preparation Example 1 180.05 90.10 92.74

Referring to Table 2 and FIGS. 6 and 7, it can be seen that the lithium secondary battery to which the cathode active material of the present invention is applied has excellent initial discharge capacity, reversible efficiency and life characteristics.

FIG. 8 is a graph showing charging and discharging at 0.1 C 0.2 C, 0.5 C, and 1.0 C, indicating that the lithium secondary battery to which the cathode active material of the present invention is applied has excellent performance.

11: core layer
12: oxide layer
13: Surface layer
21: core portion
22: surface portion
23:
24:

Claims (13)

A core layer;
An oxide layer provided on the core layer; And
And a surface layer provided on the oxide layer. The method according to claim 1,
Wherein the density of the oxide layer is lower than the density of the core layer and the surface layer. The method according to claim 1,
Wherein the thickness of the oxide layer is 0.5 to 1.5 占 퐉. a) introducing the metal hydroxide into an aqueous solution containing an aqueous sodium hydroxide solution and an aqueous ammonia solution to form a core layer in an inert atmosphere;
b) forming an oxide layer on the surface of the core layer; And
c) forming a surface layer having the same composition as the core layer on the surface of the oxide layer. 5. The method of claim 4,
And b) forming the oxide layer by exposing the core layer to an atmosphere having an oxygen concentration of 400 to 1000 ppm. 5. The method of claim 4,
Wherein the step b) comprises treating the core layer with an oxidizing agent to form the oxide layer. A core portion;
A surface portion spaced apart from the core portion;
At least one bridge portion connecting the core portion and the surface portion; And
And at least one pore portion existing between the core portion and the surface portion. 8. The method of claim 7,
Wherein a distance between the core portion and the surface portion is 0.5 to 2.5 占 퐉. 8. The method of claim 7,
Wherein the pore portion has a cut ring shape. A) preparing a cathode active material precursor prepared by the method of any one of claims 4 to 6;
B) mixing the cathode active material precursor with a lithium precursor to prepare a mixed precursor; And
C) heat treating the mixed precursor. 11. The method of claim 10,
Wherein the heat treatment in step C) is performed at 800 to 950 占 폚 for 5 to 24 hours. An anode prepared using the cathode active material of any one of claims 7 to 9. A lithium secondary battery comprising the positive electrode of claim 12.

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