KR100560534B1 - A positive active material for a lithium secondary battery and a method of preparing the same - Google Patents

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery and a method for manufacturing the same, wherein the positive electrode active material includes a core including a lithium compound and a metal oxide layer formed on at least one of the core.

Multi-layer, metal oxide, cathode active material, lithium secondary battery

Description

A positive electrode active material for a lithium secondary battery and a manufacturing method thereof {A POSITIVE ACTIVE MATERIAL FOR A LITHIUM SECONDARY BATTERY AND A METHOD OF PREPARING THE SAME}

1 is a graph showing the results of differential scanning calorimetry (DSC) of the cathode active material for a lithium secondary battery manufactured by the method of Example 4 and Comparative Example 1 of the present invention.

Figure 2 is a graph showing the DSC results of the positive electrode active material for lithium secondary batteries prepared by the method of Example 6 and Comparative Example 1 of the present invention.

Figure 3a is a graph showing the low rate charge and discharge results of the coin battery prepared in Example 13 and Comparative Example 1.

Figure 3b is a graph showing the high rate charge and discharge results of the coin battery prepared according to Example 13 and Comparative Example 1.

4 is a graph showing capacity characteristics of a coin battery prepared according to Example 13 and Comparative Example 1. FIG.

FIG. 5 is an enlarged view of FIG. 3B illustrating a high rate charge / discharge result of a coin battery prepared according to Example 13. FIG.

6 is a view showing a cyclic voltammogram (CV) of the coin cells of Example 13 and Comparative Example 1. FIG.

7 is a graph showing charge and discharge curves at 0.1C and 1C of the coin cells of Example 17 and Comparative Example 1;

8 is a graph showing the DSC analysis results of the positive electrode active materials of Examples 12 and 13 and Comparative Example 1. FIG.

9 is a graph showing capacity characteristics according to cycles for the coin cells of Example 19 and Comparative Example 3. FIG.

10 is a view showing the DSC measurement results for the positive electrode active material of Example 18 and Comparative Example 2.

11 is a graph showing the results of DSC measurements on the positive electrode active materials of Example 19 and Comparative Example 3. FIG.

FIG. 12 is a diagram showing the results of DSC measurements after overcharging the positive electrode active materials of Example 18 and Comparative Example 2. FIG.

[Industrial use]

The present invention relates to a positive electrode active material for a lithium secondary battery and a method for manufacturing the same, and more particularly, to a positive electrode active material for a lithium secondary battery excellent in thermal stability and a method for manufacturing the same.

[Prior art]

Lithium secondary batteries are manufactured by reversibly inserting and desorbing lithium ions as positive and negative electrodes, and filling an organic or polymer electrolyte between the positive and negative electrodes, and lithium ions are inserted / removed in the positive and negative electrodes. Electrical energy is generated by oxidation and reduction reactions when desorption.

Lithium metal is used as a negative electrode active material of a lithium secondary battery. However, when lithium metal is used, there is a risk of explosion due to a short circuit of the battery due to the formation of dendrite. It is going to be replaced. In particular, in recent years, boron-coated graphite (BOC) is manufactured by adding boron to a carbon-based material to increase the capacity of the carbon-based material.

As a cathode active material, a chalcogenide compound is used. Examples thereof include a composite metal such as LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiNi _1-x Co _x O ₂ (0 <x <1), and LiMnO ₂ . Oxides are being studied. Among the cathode active materials, Mn-based cathode active materials such as LiMn ₂ O ₄ and LiMnO ₂ are easy to synthesize, are relatively inexpensive, and are less attractive to the environment due to less pollution. However, they have a small capacity. LiCoO ₂ exhibits good electrical conductivity, high battery voltage, and excellent electrode characteristics, and is a representative cathode active material currently commercialized and sold by Sony Corp., but has a disadvantage of being expensive. LiNiO ₂ is the cheapest of the above-mentioned positive electrode active materials, and exhibits the highest discharge capacity of battery characteristics, but has a disadvantage of difficulty in synthesizing.

Among these, LiCoO ₂ is mainly used as a cathode active material. Recently, Sony developed LiCo _1-x Al _x O _{2 in} which a part of Co was substituted with Al by doping Al ₂ O ₃ to about 1 to 5% by weight. Developed LiCoO _{2 in} which Co was partially substituted with Sn by doping SnO ₂ .

The lithium secondary battery composed of the positive electrode and the negative electrode active material described above can be classified into a lithium ion battery, a lithium ion polymer battery and a lithium polymer battery according to the type of separator and electrolyte used. A lithium ion battery uses a porous polypropylene / polyethylene film as a separator, and refers to a battery using a carbonate-based organic solvent in which lithium salt is dissolved as an electrolyte. Lithium-ion polymer battery uses an impregnation of the organic solvent on a porous substrate based on porous SiO ₂ and the polyvinylidene fluoride-based polymer, and since the electrolyte also serves as a separator, it is not necessary to use a separate separator. none. In addition, a lithium polymer battery refers to a battery using an SO ₂ series inorganic material or organic material having pure lithium ion conductivity as an electrolyte.

Examples of the lithium secondary battery having the above configuration include a cylindrical shape, a square shape, a coin shape, and the like. In the case of a cylindrical battery, a lithium ion secondary battery is described as an example. A cathode, a cathode, and a separator are wound to produce a jelly-roll type electrode plate group, and the electrode plate is placed in a cylindrical battery case. Refers to the injected battery. A square type battery means the battery manufactured by putting the said pole plate group in a square battery case, and a coin type battery means the battery manufactured by putting the said pole plate group in the coin type battery case. In addition, depending on the material of the case can be divided into a battery and a pouch (pouch) battery using a can of steel or Al material. The can battery is said that the battery case is made of a thin plate of steel or Al, the pouch battery is a battery manufactured by putting the electrode plate group in a flexible material having a thickness of less than 1mm made of a multilayer structure such as a plastic bag, the thickness of the battery Compared to a can battery, it is thin and has a flexible structure.

Recently, as the lithium secondary battery has become smaller and lighter in electronic devices, research for developing a battery having excellent electrochemical characteristics such as high capacity and long life is being conducted.

The present invention is to solve the above problems, an object of the present invention is to provide a positive electrode active material for lithium secondary battery with improved thermal stability.

Another object of the present invention is to provide a method for producing the positive electrode active material for a lithium secondary battery.

In order to achieve the above object, the present invention is a core containing a lithium compound; And a metal oxide layer formed on at least one of the cores.

The metal that may be included in the metal oxide layer coated on the cathode active material for a lithium secondary battery is Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As and Zr It is preferably selected from, but is not limited thereto.

The metal oxide layer formed on the surface of the cathode active material for a lithium secondary battery of the present invention may include one or more metals. In addition, the metal oxide layer may be formed of two or more multiple layers including different metals.

The invention also coats a lithium compound with an organic solution or aqueous solution comprising one or more metals; It provides a method for producing a cathode active material for a lithium secondary battery comprising the step of heat-treating the coated compound.

In the coating and heat treatment process, the lithium compound may be sequentially coated and heat treated two or more times with an organic solution or an aqueous solution containing one or more metals to form a multi-layer.

Hereinafter, the present invention will be described in more detail.

The positive electrode active material for a lithium secondary battery of the present invention is composed of a core containing a lithium compound and at least one metal oxide layer formed on the core. The metal oxide layer may be a single layer including one or more metals, or may be a multi-layer including one or two or more metals.

The lithium compound constituting the core of the cathode active material of the present invention is preferably at least one compound selected from the group consisting of the following Chemical Formulas 1 to 11. Among these compounds, lithium-cobalt chalcogenide, lithium-manganese chalcogenide, lithium-nickel chalcogenide, or lithium-nickel-manganese chalcogenide compound may be more preferably used in the present invention.
[Formula 1]
Li _x Mn _1-y M ' _y A ₂
[Formula 1a]
Li _x MnA ₂
[Formula 2]
Li _x Mn _1-y M ' _y O _2-z A _z
[Formula 2a]
Li _x MnO ₂
[Formula 2b]
Li _x Mn _1-y M ' _y O ₂
[Formula 3]
Li _x Mn ₂ O _4-z A _z
[Formula 3a]
Li _x Mn ₂ O ₄
[Formula 4]
Li _x Mn _2-y M ' _y A ₄
[Formula 4a]
Li _x Mn ₂ A ₄
[Formula 5]
Li _x M _1-y M " _y A ₂
[Formula 5a]
Li _x MA ₂
[Formula 6]
Li _x MO _2-z A _z
[Formula 6a]
Li _x MO ₂
[Formula 7]
Li _x Ni _1-y Co _y O _2-z A _z
[Formula 7a]
Li _x Ni _1-y Co _y O ₂
[Formula 7b]
Li _x NiO _2-z A _z
[Formula 7c]
Li _x NiO ₂
[Formula 8]
Li _x Ni _1-yz Co _y M " _z A _α
[Formula 8a]
Li _x NiM " _z A _α
[Formula 8b]
Li _x Ni _1-y Co _y A _α
[Formula 8c]
Li _x NiA _α
[Formula 9]
Li _x Ni _1-yz Co _y M " _z O _2-α A _α
[Formula 9a]
Li _x NiM " _z O _2-α A _α
[Formula 9b]
Li _x Ni _1-y Co _y O _2-α A _α
[Formula 9c]
Li _x NiO _2-α A _α
[Formula 10]
Li _x Ni _1-yz Mn _y M ' _z A _α
[Formula 10a]
Li _x Ni _1-z M ' _z A _α
[Formula 10b]
Li _x Ni _1-y Mn _y A _α
[Formula 10c]
Li _x NiA _α
[Formula 11]
Li _x Ni _1-yz Mn _y M ' _z O _2-α A _α
[Formula 11a]
Li _x Ni _1-y Mn _y O _2-α A _α
[Formula 11b]
Li _x Ni _1-z M ' _z O _2-α A _α
[Formula 11c]
Li _x NiO _2-α A _α

Wherein 0.95 ≦ x ≦ 1.1, 0 <y ≦ 0.5, 0 <z ≦ 0.5, 0 <α ≦ 2, M is Ni or Co, M ′ is Al, Ni, Co, Cr, Fe, Mg , Sr, V, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu , Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr, at least one element selected from the group, M "is Al, Cr, Mn, Fe, Mg, Sr, V, Sc, Y , La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf , Es, Fm, Md, No, and at least one element selected from the group consisting of Lr, A is an element selected from the group consisting of O, F, S and P.)

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At least one metal oxide formed on the surface of the lithium compound is an oxide of a metal selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Ga, Ge, B, As and Zr. It is preferable.

The content of the metal in the at least one metal oxide layer is preferably 2x10 ^-5 to 1% by weight, more preferably 0.001 to 1% by weight based on the positive electrode active material.

The positive electrode active material of the present invention is characterized in that the phase transition occurs in the voltage range of 4.0V to 4.3V during charging and discharging. In addition, the cathode active material of the present invention has a high heat generation temperature of 230 ° C. or higher and a small amount of heat generation, thereby providing excellent thermal stability.

In the present invention, an organic solution or an aqueous metal solution containing a metal is used as the coating solution of the lithium compound.

As the metal used in the preparation of the coating solution, any one dissolved in an organic solvent or water may be used, and representative examples thereof include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, and Ga. , B, As or Zr.

The metal organic solution may be prepared by dissolving a metal, a metal alkoxide, a metal salt, a metal oxide, or the like in an organic solvent, or by refluxing the mixture. The aqueous metal solution may be prepared by dissolving a metal salt or metal oxide in water, or by refluxing the mixture. Suitable forms of metals that are soluble in organic solvents or water may be selected by one of ordinary skill in the art. For example, the coating solution containing boron may be prepared by dissolving HB (OH) ₂ , B ₂ O ₃ , H ₃ BO ₃ , and the like in an organic solvent or water.

Organic solvents usable in the preparation of metal organic solutions in the coating solution include alcohols such as methanol, ethanol or isopropanol, hexane, chloroform, tetrahydrofuran, ether, methylene chloride, acetone and the like.

The metal alkoxide solution prepared by dissolving a metal alkoxide such as metal methoxide, metal ethoxide or metal isopropoxide in the alcohol in the alcohol may be preferably used in the present invention. As an example of such a metal alkoxide solution, a Si alkoxide solution is a tetraethylorthosilicate solution or a tetraethylorthosilicate solution prepared by dissolving silicate in ethanol.

Representative examples of metal salts or metal oxides that may be used in preparing the metal aqueous solution in the coating solution include vanadate such as ammonium vanadate (NH ₄ (VO ₃ )), vanadium oxide (V ₂ O ₅ ), and the like.

The amount of the metal, metal alkoxide, metal salt or metal oxide added in the preparation of the metal organic solution or the metal aqueous solution is 0.1 to 50% by weight, more preferably 1 to 20% by weight based on the organic solution or the aqueous solution. When the concentration of the metal, metal alkoxide, metal salt or metal oxide is lower than 0.1% by weight, there is no effect of coating the lithium compound with a metal organic solution or an aqueous metal solution, and the concentration of the metal, metal alkoxide, metal salt, or metal oxide is If it exceeds 50% by weight, the thickness of the coating layer is too thick, which is not preferable.

The lithium compound is coated with the metal organic solution or the metal aqueous solution prepared as described above.

As the coating method, a general coating method such as sputtering, chemical vapor deposition (CVD), dip coating, which is an impregnation method, may be used, but powder, which is the simplest coating method, is simply dipped in the coating solution. It is preferable to use the dip coating method taken out.

The coating process may be performed using an organic solution or an aqueous solution containing one or more metals so that one or more metals are included in one coating layer. In addition, after the first coating with a first organic solution or a first aqueous solution containing one or more metals and heat treatment, the second coating with a second organic solution or a second aqueous solution containing one or more metals, followed by heat treatment to form a double layer You may. Three or more coatings and heat treatments may be sequentially performed with an organic solution or an aqueous solution containing one or more metals so as to have three or more metal oxide coating layers.

When the coating process is performed by mixing at least one metal organic solution or a metal aqueous solution, it is preferable to mix the solutions to be used in the same volume.

Regardless of the number of coating processes, a heat treatment process is performed after the coating is performed, and the heat treatment process is performed at 200 to 800 ° C. for 1 to 20 hours. In order to produce a more uniform crystalline active material, the heat treatment process is preferably performed under conditions of flowing dry air. In this case, when the heat treatment temperature is lower than 200 ° C., the coated metal organic solution or the metal aqueous solution is not crystallized, and thus, when the active material is applied to the battery, the movement of lithium ions may be disturbed. In addition, when the heat treatment temperature is higher than 800 ° C., the evaporation of lithium and the crystallinity of the metal oxide layer formed on the surface become high, which causes a problem in the movement of Li ⁺ . In addition, even when the heat treatment time is out of the above range, there is a problem in the movement of Li ⁺ due to the evaporation of lithium and the crystallinity of the metal oxide layer formed on the surface.

The heat treatment process converts the metal organic solution or the metal aqueous solution into a metal oxide. Therefore, in the case where coating is performed once by mixing a metal organic solution or an aqueous metal solution, AB oxide (A and B are Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge on the surface, respectively). Selected from the group consisting of Ga, B, As, and Zr, and are not identical to each other.) A single layer is formed, and when two or more coating processes are performed, an A oxide layer and a B oxide layer formed on the layer, etc. Multiple layers of are formed.

It is preferable that the thickness of the metal oxide layer formed in the surface by the said process is 1-100 nm, and it is more preferable that it is 1-50 nm. If the thickness of the metal oxide layer formed on the surface is less than 1 nm, the effect of coating with the metal oxide is insignificant. If the thickness exceeds 100 nm, the thickness of the coating layer is too thick, which is not preferable.

After the heat treatment, the obtained product is cooled to about 200 to 500 ° C. in the furnace, and then rapidly taken out into the atmosphere, that is, a quenching process may be performed at room temperature. A slow cooling process can be performed to take out in the middle. When performing a quenching step, the quenching rate is preferably 0.5 ° C / min or more.

As the lithium compound used in the present invention, a commercially available compound may be used, or a synthesized lithium compound may be used, or these lithium compounds may be mixed and used.

Synthesis method of the lithium compound is as follows. First, lithium salts and metal salts are mixed at a desired equivalent ratio. As the lithium salt, generally, any one used to prepare a cathode active material for a manganese-based lithium secondary battery may be used, and representative examples thereof may include lithium nitrate, lithium acetate, lithium hydroxide, and the like. Manganese salt, cobalt salt, nickel salt or nickel manganese salt may be used as the metal salt. The manganese salt may be used, such as manganese acetate, manganese dioxide, the cobalt salt may be used such as cobalt hydroxide, cobalt nitrate or cobalt carbonate, nickel salts, nickel hydroxide, nickel nitrate Or nickel acetate. The nickel manganese salt may be prepared by precipitating nickel salt and manganese salt by coprecipitation method. As the metal salt, fluorine salt, sulfur salt or phosphorus salt may be precipitated together with manganese salt, cobalt salt, nickel salt or nickel manganese salt. Manganese fluoride, lithium fluoride, or the like may be used as the fluorine salt. Manganese sulfide, lithium sulfide, or the like may be used as the sulfur salt, and H ₃ PO ₄ may be used as the phosphate salt. The manganese salt, cobalt salt, nickel salt, nickel manganese salt, fluorine salt, sulfur salt and phosphorus salt are not limited to the compound.

At this time, in order to promote the reaction between the lithium salt and the metal salt, an appropriate solvent such as ethanol, methanol, water, acetone may be added and mortar grinder mixing may be performed until the solvent is almost gone. have.

The obtained mixture is heat-treated at a temperature of about 400 to 600 ° C. to prepare a lithium compound precursor powder in a semi crystalline state. If the heat treatment temperature is lower than 400 ℃ there is a problem that the reaction between the lithium salt and the metal salt is not sufficient. When the primary heat treatment temperature is lower than 400 ° C., the reaction between the lithium salt and the metal salt is not sufficient. In addition, the lithium salt may be uniformly distributed by drying the precursor powder prepared by heat treatment, or by remixing the cathode active material precursor powder at room temperature while blowing dry air after the heat treatment process.

The semi-crystalline precursor powder obtained is subjected to secondary heat treatment at a temperature of 700 to 900 ° C. for about 10 to 15 hours. If the secondary heat treatment temperature is lower than 700 ° C, there is a problem that the crystalline material is difficult to form. The heat treatment step is carried out by heating at a rate of 1 to 5 ℃ / min under the conditions of blowing dry air or oxygen, it is maintained by a certain time at each heat treatment temperature and then naturally cooled.

Subsequently, the powder of the prepared lithium compound may be remixed at room temperature to distribute the lithium salt more uniformly.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only one preferred embodiment of the present invention and the present invention is not limited to the following examples.

(Comparative Example 1)

LiCoO ₂ powder having an average particle diameter of 10 μm, a super P carbon conductive material, and a polyvinylidene fluoride binder were measured at a mass ratio of 94: 3: 3, and then dissolved in an N-methylpyrrolidone solvent to prepare a cathode active material slurry. The slurry was cast on Al-foil, dried and pressed to prepare a positive electrode plate for a coin battery.

A coin-type half cell was manufactured in an Ar-purged glove box using lithium metal as a positive electrode plate and a counter electrode. At this time, the electrolyte solution is dissolved 1M LiPF ₆ A standard electrolyte solution of a mixed solvent of ethylene carbonate and dimethyl carbonate (1: 1 volume ratio) was used.

(Comparative Example 2)

Instead of LiCoO ₂ as a positive electrode active material _{Li 1.03 Ni 0.69 Mn 0.19 Co 0.1} Al 0.07 Mg 0.07 O 2 ( average particle diameter: 10㎛) and the coin-type half-cell was produced in the same manner as in Comparative Example 1 except for using.

(Comparative Example 3)

A coin-type half cell was manufactured in the same manner as in Comparative Example 1, except that LiNi _0.9 Co _0.1 Sr _0.002 O ₂ (average particle diameter: 10 μm) was used instead of LiCoO ₂ as the cathode active material.

(Comparative Example 4)

A coin-type half cell was manufactured in the same manner as in Comparative Example 1, except that LiMn ₂ O ₄ (average particle diameter: 20 μm) was used instead of LiCoO ₂ as the cathode active material.

(Example 1)

Al-isopropoxide powder was added to ethanol to prepare a 5% by weight Al-isopropoxide solution.

100 g of LiCoO ₂ powder having an average particle diameter of 10 μm was added to the Al-isopropoxide solution and stirred for about 10 minutes with a stirrer so that the Al-isopropoxide solution could be evenly coated on the surface of the LiCoO ₂ powder. It was. The slurry thus prepared was left to stand for about 30 minutes to separate the slurry and the Al-isopropoxide solution, and then the Al-isopropoxide solution was removed, and only the slurry was placed in a furnace for heat treatment.

After heat-processing at 300 degreeC for 10 hours, flowing dry air at the temperature increase rate of 3 degree-C / min in a furnace, it cooled in the furnace. When the furnace temperature was about 200 ° C., the heat treatment furnace was taken out into the air, quenched, left in air, and when the temperature reached room temperature, the powder was pulverized and classified to finally prepare the cathode active material powder. Using a positive electrode active material powder thus prepared was prepared a coin-type half-cell in the same manner as in Comparative Example 1.

(Example 2)

A coin-type half cell was prepared in the same manner as in Example 1 except that the heat treatment temperature was changed from 300 ° C. to 500 ° C.

(Example 3)

A coin-type half cell was manufactured by the same method as Example 1 except that the heat treatment temperature was changed from 300 ° C. to 700 ° C.

(Example 4)

The core / shell type LiCoO ₂ powder coated on the surface of the aluminum oxide prepared by the first heat treatment in Example 1 was immersed in a sufficient tetraethylorthosilicate solution (Aldrich), followed by stirring to give a secondary coating. The secondary coated LiCoO ₂ powder was separated into a solution and a slurry in the same manner as in Example 1, and then the slurry was heat-treated at 300 ° C. for 10 hours to coat the secondary silicon oxide on the aluminum oxide-coated powder. Multi-layer LiCoO ₂ powder was synthesized.

A coin-type half cell was manufactured in the same manner as in Comparative Example 1 using the prepared multilayer LiCoO ₂ powder.

(Example 5)

In the same manner as in Example 4 except for using a core / shell-type LoCoO ₂ powder coated with aluminum oxide prepared by the method of Example 2 and changing the heat treatment temperature from 300 ° C. to 700 ° C. The coin-type half cell was produced.

(Example 6)

Aluminum oxide prepared by the method of Example 3 was carried out in the same manner as in Example 4, except that the core / shell type LiCoO ₂ coated on the surface, and the heat treatment temperature was changed from 300 ℃ to 500 ℃ The coin-type half cell was produced.

(Example 7)

A coin-type half cell was prepared in the same manner as in Example 4, except that a mixed solution of Al-isopropoxide solution and tetraethylorthosilicate solution was used instead of the Al-isopropoxide solution. .

(Example 8)

In place of the Al-isopropoxide solution, 5% by weight of aluminum nitrate solution prepared by adding Al (NO ₃ ) ₃ to water was used in the same manner as in Example 1 Half cell was prepared.

(Example 9)

Instead of the Al-isopropoxide solution, a 5 wt% aluminum nitrate solution prepared by adding Al (NO ₃ ) ₃ to water was used, except that the heat treatment temperature was changed from 300 ° C. to 500 ° C. A coin-type half cell was prepared in the same manner as in Example 1 above.

(Example 10)

Instead of the Al-isopropoxide solution, a 5 wt% aluminum nitrate solution prepared by adding Al (NO ₃ ) ₃ to water was used, except that the heat treatment temperature was changed from 300 ° C. to 700 ° C. A coin-type half cell was prepared in the same manner as in Example 1 above.

The lithium secondary batteries prepared by the methods of Examples 1 to 10 and Comparative Example 1 were charged at a current of 0.1 C-rate to 4.3V. After discharging the charged battery in the glove box, only 10mg of the active material was taken from the electrode plate was used as a sample. Using this sample, the thermal stability of the positive electrode active material was measured by differential scanning calorimetry (DSC) scanning using a Perkin Helmer Co. product from 25 to 300 ° C. under an air atmosphere at a rate of 3 ° C./min. .

DSC analysis was performed to confirm the thermal stability of the charged cathode active material. In general, the safety of the lithium secondary battery (safety) is carried out by a variety of mechanisms, in particular, it is known that one of the most important safety experiments to penetrate the nail in the state of charge. At this time, there are various factors affecting the safety of the charged battery. In particular, it is known that the exothermic reaction by the reaction of the charged positive electrode and the electrolyte solution impregnated in the electrode plate plays an important role. A coin battery was manufactured by a method of comparatively judging such a phenomenon, and then charged to a constant potential to make a Li _1-x CoO ₂ state, and then the exothermic temperature, calorific value, and exothermic curve displayed through DSC measurement of the material in this state of charge. Based on the results of the safety can be judged.

This will be described using LiCoO ₂ as an example. LiCoO ₂ has a structure of Li _1-x CoO ₂ in a charged state. Since the active material having such a structure is unstable, when the temperature inside the battery is high, oxygen, ie, oxygen bound with cobalt, is released from the metal. Freed oxygen is likely to react with the electrolyte inside the cell, providing an opportunity for the cell to explode. Therefore, the oxygen decomposition temperature and the calorific value at this time can be said to be an important factor indicating the stability of the battery.

1 is a DSC measurement result of Example 4 and Comparative Example 1, Figure 2 is a DSC measurement result of Example 6 and Comparative Example 1. As shown in FIG. 1, Example 4 has a heat generation temperature of about 214 ° C., while Comparative Example 1 has a heat generation temperature of about 209 ° C., and the positive electrode active material of Example 4 has a higher heat generation temperature than that of Comparative Example 1 and is gentle. It can be seen that the thermal stability is excellent because it has a heating curve. At this time, the amount of the electrolyte solution impregnated into the positive electrode active material of Example 4 and Comparative Example 1 was 0.006g, the charge amount was 161mAh / g.

In addition, as shown in FIG. 2, the exothermic temperature of Example 6 is 234 ° C., whereas Comparative Example 1 is 225 ° C. and Example 6 exhibits a higher exothermic temperature than Comparative Example 1, indicating that the thermal stability is better. have.

(Example 11)

Coin-type halves were prepared in the same manner as in Example 1, except that 10% by weight of the boron ethoxide solution prepared by dissolving 10% by weight of B ₂ O ₃ powder in 90% by weight of ethanol was used as a coating solution. The battery was prepared.

(Example 12)

A coin-type half cell was prepared by carrying out the same method as Example 1 except that 10 wt% of the boron ethoxide solution was used as a coating solution and the heat treatment temperature after coating was 500 ° C.

(Example 13)

A coin-type half cell was prepared by carrying out the same method as Example 1 except that 10 wt% of the boron ethoxide solution was used as a coating solution and the heat treatment temperature after coating was 700 ° C.

(Example 14)

10% by weight of B ₂ O ₃ powder was dissolved in 90% by weight of ethanol to prepare a boron ethoxide solution. LiCoO ₂ powder having an average particle diameter of 10 μm was subjected to a coating process in the same manner as in Example 1 using the boron ethoxide solution to prepare LiCoO ₂ powder coated with boron oxide.

Boron oxide-coated LiCoO ₂ powder is a core / shell type multi-layer LiCoO with secondary coating of aluminum oxide on the surface in the same manner as in Example 1 using 1% by weight of Al-isopropoxide solution ₂ powders were synthesized.

A coin-type half cell was manufactured in the same manner as in Comparative Example 1 using the prepared multilayer LiCoO ₂ powder.

(Example 15)

A coin-type half cell was prepared in the same manner as in Example 14, except that 1 wt% of boron ethoxide solution was used as the coating solution.

(Example 16)

A coin-type half cell was prepared in the same manner as in Example 14, except that 1% by weight of boron ethoxide solution was used as the coating solution and the heat treatment temperature after coating was 500 ° C.

(Example 17)

A coin-type half cell was prepared in the same manner as in Example 14, except that 1% by weight of boron ethoxide solution was used as a coating solution and the heat treatment temperature after coating was 700 ° C.

Using the coin-type half cell of Example 13, after performing charge / discharge in the range of 4.3V-2.75V at 0.5C charge / discharge rate, the result is shown to FIG. 3A. For comparison, the result of charging and discharging of the coin-type half cell of Comparative Example 1 including LiCoO ₂ , which is not conventionally treated, is also shown. As shown in FIG. 3A, it can be seen that the half cell of Example 13 has better discharge potential and capacity characteristics than the battery of Comparative Example 1. FIG. Moreover, after performing charge / discharge in the range of 4.3V-2.75V at 1C charge / discharge rate, the result is shown to FIG. 3B. As shown in FIG. 3B, the battery using the active material of Example 10 had better discharge potential and capacity characteristics as compared to Comparative Example 1, even at a high rate of charge and discharge of 1C. The discharge capacities of the batteries shown in FIGS. 3A and 3B are also shown in FIG. 4. It can be seen that the battery of Example 13 has better capacity characteristics according to cycles than Comparative Example 1.

When the charge and discharge curves of the battery according to Example 13 of FIG. 3b were observed, the charge and discharge curves were slightly deformed between 4.0V and 4.3V. 5 shows an enlarged view of a charge / discharge curve of a battery including the active material of Example 10 in the charge / discharge curve of FIG. 3B. The deformation of the charge / discharge curve is presumed to be a result of the phase transition of the positive electrode active material. In order to confirm this fact, cyclic voltammetry analysis was performed on the half cell containing the positive electrode active material of Example 13. The cyclic voltammogram obtained by scanning at a rate of 0.5 mV / sec in the range of 5.0 V to 2.5 V is shown in FIG. 6. For comparison, the half cell of Comparative Example 1 to which LiCoO ₂ without conventional surface treatment was applied was also shown in FIG. 6 under cyclic voltamograms under the same conditions. As shown in FIG. 6, only one peak was observed during the charging and discharging of the battery including LiCoO ₂ , whereas two peaks were observed during the charging and discharging of the battery including the active material of Example 10. Thus, the active material prepared according to Example 13 of the present invention can be confirmed that the structural change occurs during charging and discharging.

For the coin battery prepared according to Example 17, 0.1C and 1C charge and discharge results in a voltage range of 4.3 to 2.75V are shown in FIG. 7. In FIG. 7, a slight deformation of the charge / discharge curve was observed between 4.0V and 4.3V. The positive electrode active material prepared according to Example 17 may also predict that phase transition occurred in the voltage region.

In the same manner as the coin cells of Examples 1 to 10, the coin cells of Examples 11 to 17 were charged to 4.3 V, and then disassembled in a glove box to separate the electrode plates. About 10 mg of only the active material coated on the Al-foil was collected from the separated electrode plate and subjected to DSC analysis using a 910 DSC (manufactured by TA Instrument). DSC analysis was performed by scanning at a temperature increase rate of 3 ° C./min in a temperature range of 25 to 300 ° C. in an air atmosphere. The measurement results of Examples 12 and 13 are shown in FIG. 8.

This result is formed on the surface of LiCoO ₂ powder is at least one metal oxide being heat treated and surface treated with one or more metal alkoxides LiCoO ₂ can be interpreted as a crystal structure of LiCoO ₂ stabilized. In other words, it is assumed that the surface crystal structure of LiCoO ₂ is stabilized and the bond between cobalt and oxygen is stabilized. In addition, by forming a metal oxide layer such as Al ₂ O ₃ , SiO ₂ , B ₂ O ₃ on the surface of LiCoO ₂ can be interpreted that the reactivity of the positive electrode active material and the electrolyte solution is suppressed to reduce the oxidation of the electrolyte solution.

Combustion, thermal exposure and overcharge tests were carried out on 20 2000 mAh cylindrical batteries containing the positive electrode active materials in Comparative Example 1 and Examples 15 to 17. In the combustion test, the burst rate of the battery was calculated by heating the battery with a burner. The thermal exposure test measured the time that the battery ruptured when the battery was thermally exposed at 150 ° C., and the overcharge test was leakage when the battery was overcharged to 1C. The rate was investigated. The results are shown in Table 1 below.

Comparative Example 1 Example 15 Example 16 Example 17 Burst Rate on Combustion 90% 0% 0% 0% Bursting time of battery during thermal exposure (average) 11 minutes 12 minutes 15 minutes 20 minutes 1C Overcharge Leakage Rate 100% 30% 10% 0%

(Example 18)

Li _1.03 Ni _0.69 Mn _0.19 Co _0.1 Al _0.07 Mg _0.07 O ₂ (average particle size: 10㎛) instead of LiCoO _{2 with a} lithium compound coated with 1% by weight of boron ethoxide solution and then heat-treated at 700 ℃ A coin-type half cell was prepared in the same manner as in Example 13.

(Example 19)

LiNi _0.9 Co _0.1 Sr _0.002 O ₂ (average particle diameter: 10 μm) instead of LiCoO _{2 with a} lithium compound in the same manner as in Example 13 except for the heat treatment at 700 ℃ after 1% by weight of the boron ethoxide solution Coin type half cells were prepared.

(Example 20)

Li _1.03 Ni _0.69 Mn _0.19 Co _0.1 Al _0.07 Mg _0.07 O ₂ (average particle size: 10㎛) instead of LiCoO _{2 with a} lithium compound coated with 1% by weight of boron ethoxide solution and then heat-treated at 700 ℃ A coin-type half cell was prepared in the same manner as in Example 14.

(Example 21)

LiNi _0.9 Co _0.1 Sr _0.002 O ₂ (average particle diameter: 10 μm) instead of LiCoO _{2 with a} lithium compound in the same manner as in Example 14 except for the heat treatment at 700 ℃ after 1% by weight of the boron ethoxide solution Coin type half cells were prepared.

(Example 22)

A coin-type half cell was manufactured in the same manner as in Example 15, except that LiNi _0.9 Co _0.1 Sr _0.002 O ₂ (average particle diameter: 10 μm) was used instead of LiCoO ₂ as a lithium compound.

(Example 23)

A coin-type half cell was manufactured in the same manner as in Example 16, except that LiNi _0.9 Co _0.1 Sr _0.002 O ₂ (average particle diameter: 10 μm) was used instead of LiCoO ₂ as the lithium compound.

(Example 24)

A coin-type half cell was manufactured in the same manner as in Example 17, except that LiNi _0.9 Co _0.1 Sr _0.002 O ₂ (average particle diameter: 10 μm) was used instead of LiCoO ₂ as a lithium compound.

(Example 25)

A coin-type half cell was manufactured in the same manner as in Example 15, except that LiMn ₂ O ₄ (average particle diameter: 20 μm) was used instead of LiCoO ₂ as the lithium compound.

(Example 26)

A coin-type half cell was manufactured in the same manner as in Example 16, except that LiMn ₂ O ₄ (average particle diameter: 20 μm) was used instead of LiCoO ₂ as the lithium compound.

(Example 27)

A coin-type half cell was manufactured in the same manner as in Example 17, except that LiMn ₂ O ₄ (average particle diameter: 20 μm) was used instead of LiCoO ₂ as the lithium compound.

C in the order of 0.1 C (1 cycle), 0.2 C (3 cycles), 0.5 C (10 cycles) and 1 C (6 cycles) in sequence for the batteries prepared by the methods of Examples 18 to 27 and Comparative Examples 2 to 4 The discharge capacity was measured by charging and discharging in the voltage range of 4.3V to 2.75V while changing the rate. Capacity characteristics of the batteries of Example 19 and Comparative Example 3 according to cycles are illustrated in FIG. 9. As shown in FIG. 9, the battery of Example 19 showed better cycle capacity characteristics and higher discharge potential than Comparative Example 3.

After charging the coin cells of Examples 18 and 19 to 4.3V and dismantled in a glove box, only 10mg of the active material was taken from the electrode plate and used as a sample. This sample was subjected to DSC scanning at 25 to 300 ° C. under an air atmosphere at a rate of 3 ° C./minute using a 910 DSC (manufactured by TA Instrument) to measure thermal stability. DSC scans were also performed on the coin cells of Comparative Example 2 using Li _1.03 Ni _0.69 Mn _0.19 Co _0.1 Al _0.07 Mg _0.07 O ₂ without surface treatment and Comparative Example 3 using LiNi _0.9 Co _0.1 Sr _0.002 O ₂ without surface treatment. It was. The DSC measurement results of Example 18 and Comparative Example 2 are shown in FIG. The DSC measurement results of Example 19 and Comparative Example 3 are shown in FIG.

After overcharging the coin batteries of Example 18 and Comparative Example 2 to 4.45V and dismantled in a glove box, only 10mg of the active material was taken from the electrode plate and used as a sample. Using this sample, DSC scan was carried out to 25-300 degreeC in air atmosphere at the speed of 3 degree-C / min. The DSC measurement results of Example 18 and Comparative Example 2 after overcharging are shown in FIG. 12.

As shown in FIG. 10, the exothermic peak of Comparative Example 2 was shown to be large at about 220 ° C., but the exothermic curve of Example 18 was nearly horizontal, showing no exothermic peak. This indicates that the amount of heat generated by the cathode active material of Example 18 is much lower than that of the cathode active material of Comparative Example 2, and it can be seen that the thermal stability of the cathode active material according to the present invention is much better. These results can also be confirmed in FIG. 11, which shows the DSC measurement results of Example 19 and Comparative Example 3. FIG. In addition, it can be seen that the gap between the areas of the exothermic peaks of Example 18 and Comparative Example 2 is further increased from FIG. 12, which is a DSC measurement result after overcharge. It was found that the positive electrode active material used in the battery prepared according to the remaining examples also has excellent thermal stability.

As described above, the positive electrode active material for a lithium secondary battery of the present invention has significantly improved thermal stability as the metal oxide layer is formed on the surface of the oxide layer containing one or more metals. A significant effect can be obtained.

Claims (22)

A core comprising a lithium compound; And At least one metal oxide layer formed over the core, wherein the metal oxide layer comprises at least two different metals A cathode active material for a lithium secondary battery comprising a. The positive active material of claim 1, wherein the lithium compound is at least one compound selected from the group consisting of Chemical Formulas 1 to 11. [Formula 1] Li _x Mn _1-y M ' _y A ₂ [Formula 1a] Li _x MnA ₂ [Formula 2] Li _x Mn _1-y M ' _y O _2-z A _z [Formula 2a] Li _x MnO ₂ [Formula 2b] Li _x Mn _1-y M ' _y O ₂ [Formula 3] Li _x Mn ₂ O _4-z A _z [Formula 3a] Li _x Mn ₂ O ₄ [Formula 4] Li _x Mn _2-y M ' _y A ₄ [Formula 4a] Li _x Mn ₂ A ₄ [Formula 5] Li _x M _1-y M " _y A ₂ [Formula 5a] Li _x MA ₂ [Formula 6] Li _x MO _2-z A _z [Formula 6a] Li _x MO ₂ [Formula 7] Li _x Ni _1-y Co _y O _2-z A _z [Formula 7a] Li _x Ni _1-y Co _y O ₂ [Formula 7b] Li _x NiO _2-z A _z [Formula 7c] Li _x NiO ₂ [Formula 8] Li _x Ni _1-yz Co _y M " _z A _α [Formula 8a] Li _x NiM " _z A _α [Formula 8b] Li _x Ni _1-y Co _y A _α [Formula 8c] Li _x NiA _α [Formula 9] Li _x Ni _1-yz Co _y M " _z O _2-α A _α [Formula 9a] Li _x NiM " _z O _2-α A _α [Formula 9b] Li _x Ni _1-y Co _y O _2-α A _α [Formula 9c] Li _x NiO _2-α A _α [Formula 10] Li _x Ni _1-yz Mn _y M ' _z A _α [Formula 10a] Li _x Ni _1-z M ' _z A _α [Formula 10b] Li _x Ni _1-y Mn _y A _α [Formula 10c] Li _x NiA _α [Formula 11] Li _x Ni _1-yz Mn _y M ' _z O _2-α A _α [Formula 11a] Li _x Ni _1-y Mn _y O _2-α A _α [Formula 11b] Li _x Ni _1-z M ' _z O _2-α A _α [Formula 11c] Li _x NiO _2-α A _α Wherein 0.95 ≦ x ≦ 1.1, 0 <y ≦ 0.5, 0 <z ≦ 0.5, 0 <α ≦ 2, M is Ni or Co, M ′ is Al, Ni, Co, Cr, Fe, Mg , Sr, V, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu , Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr, at least one element selected from the group, M "is Al, Cr, Mn, Fe, Mg, Sr, V, Sc, Y , La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf , Es, Fm, Md, No, and at least one element selected from the group consisting of Lr, A is an element selected from the group consisting of O, F, S and P.) The cathode active material of claim 1, wherein the metal content of the metal oxide layer is 2 × 10 ⁻⁵ to 1 wt% based on the cathode active material. The cathode active material of claim 3, wherein the metal content of the metal oxide layer is 0.001 to 1 wt% based on the cathode active material. delete The metal of claim 1, wherein the metal in the metal oxide layer is at least one selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, and Zr. The positive electrode active material for lithium secondary batteries which is a metal. A core comprising a lithium compound; And Two or more metal oxide layers sequentially formed on the core, wherein the metal oxide layers comprise different metals from one another A cathode active material for a lithium secondary battery comprising a. The cathode active material of claim 7, wherein the lithium compound is at least one compound selected from the group consisting of Chemical Formulas 1 to 11. 9.  [Formula 1] Li _x Mn _1-y M ' _y A ₂ [Formula 1a] Li _x MnA ₂ [Formula 2] Li _x Mn _1-y M ' _y O _2-z A _z [Formula 2a] Li _x MnO ₂ [Formula 2b] Li _x Mn _1-y M ' _y O ₂ [Formula 3] Li _x Mn ₂ O _4-z A _z [Formula 3a] Li _x Mn ₂ O ₄ [Formula 4] Li _x Mn _2-y M ' _y A ₄ [Formula 4a] Li _x Mn ₂ A ₄ [Formula 5] Li _x M _1-y M " _y A ₂ [Formula 5a] Li _x MA ₂ [Formula 6] Li _x MO _2-z A _z [Formula 6a] Li _x MO ₂ [Formula 7] Li _x Ni _1-y Co _y O _2-z A _z [Formula 7a] Li _x Ni _1-y Co _y O ₂ [Formula 7b] Li _x NiO _2-z A _z [Formula 7c] Li _x NiO ₂ [Formula 8] Li _x Ni _1-yz Co _y M " _z A _α [Formula 8a] Li _x NiM " _z A _α [Formula 8b] Li _x Ni _1-y Co _y A _α [Formula 8c] Li _x NiA _α [Formula 9] Li _x Ni _1-yz Co _y M " _z O _2-α A _α [Formula 9a] Li _x NiM " _z O _2-α A _α [Formula 9b] Li _x Ni _1-y Co _y O _2-α A _α [Formula 9c] Li _x NiO _2-α A _α [Formula 10] Li _x Ni _1-yz Mn _y M ' _z A _α [Formula 10a] Li _x Ni _1-z M ' _z A _α [Formula 10b] Li _x Ni _1-y Mn _y A _α [Formula 10c] Li _x NiA _α [Formula 11] Li _x Ni _1-yz Mn _y M ' _z O _2-α A _α [Formula 11a] Li _x Ni _1-y Mn _y O _2-α A _α [Formula 11b] Li _x Ni _1-z M ' _z O _2-α A _α [Formula 11c] Li _x NiO _2-α A _α Wherein 0.95 ≦ x ≦ 1.1, 0 <y ≦ 0.5, 0 <z ≦ 0.5, 0 <α ≦ 2, M is Ni or Co, M ′ is Al, Ni, Co, Cr, Fe, Mg , Sr, V, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu , Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr, at least one element selected from the group, M "is Al, Cr, Mn, Fe, Mg, Sr, V, Sc, Y , La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf , Es, Fm, Md, No, and at least one element selected from the group consisting of Lr, A is an element selected from the group consisting of O, F, S and P.) The cathode active material of claim 7, wherein a content of the metal in the metal oxide layer is 2 × 10 ⁻⁵ to 1 wt% based on the cathode active material. The cathode active material of claim 9, wherein the metal content of the metal oxide layer is 0.001 to 1 wt% based on the cathode active material. 8. The method of claim 7, wherein the metal in the metal oxide layer is at least one selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As and Zr. The positive electrode active material for lithium secondary batteries which is a metal. The cathode active material of claim 7, wherein the metal oxide layer comprises two or more metals. Coating a lithium compound using a metal organic solution or aqueous metal solution, wherein the metal organic solution or aqueous metal solution comprises two or more different metals; And Heat-treating the coated compound Including, A method of manufacturing a cathode active material for a lithium secondary battery, wherein the coating and heat treatment steps are performed one or more times. The method of claim 13, wherein the lithium compound is at least one compound selected from the group consisting of Chemical Formulas 1 to 11.  [Formula 1] Li _x Mn _1-y M ' _y A ₂ [Formula 1a] Li _x MnA ₂ [Formula 2] Li _x Mn _1-y M ' _y O _2-z A _z [Formula 2a] Li _x MnO ₂ [Formula 2b] Li _x Mn _1-y M ' _y O ₂ [Formula 3] Li _x Mn ₂ O _4-z A _z [Formula 3a] Li _x Mn ₂ O ₄ [Formula 4] Li _x Mn _2-y M ' _y A ₄ [Formula 4a] Li _x Mn ₂ A ₄ [Formula 5] Li _x M _1-y M " _y A ₂ [Formula 5a] Li _x MA ₂ [Formula 6] Li _x MO _2-z A _z [Formula 6a] Li _x MO ₂ [Formula 7] Li _x Ni _1-y Co _y O _2-z A _z [Formula 7a] Li _x Ni _1-y Co _y O ₂ [Formula 7b] Li _x NiO _2-z A _z [Formula 7c] Li _x NiO ₂ [Formula 8] Li _x Ni _1-yz Co _y M " _z A _α [Formula 8a] Li _x NiM " _z A _α [Formula 8b] Li _x Ni _1-y Co _y A _α [Formula 8c] Li _x NiA _α [Formula 9] Li _x Ni _1-yz Co _y M " _z O _2-α A _α [Formula 9a] Li _x NiM " _z O _2-α A _α [Formula 9b] Li _x Ni _1-y Co _y O _2-α A _α [Formula 9c] Li _x NiO _2-α A _α [Formula 10] Li _x Ni _1-yz Mn _y M ' _z A _α [Formula 10a] Li _x Ni _1-z M ' _z A _α [Formula 10b] Li _x Ni _1-y Mn _y A _α [Formula 10c] Li _x NiA _α [Formula 11] Li _x Ni _1-yz Mn _y M ' _z O _2-α A _α [Formula 11a] Li _x Ni _1-y Mn _y O _2-α A _α [Formula 11b] Li _x Ni _1-z M ' _z O _2-α A _α [Formula 11c] Li _x NiO _2-α A _α Wherein 0.95 ≦ x ≦ 1.1, 0 <y ≦ 0.5, 0 <z ≦ 0.5, 0 <α ≦ 2, M is Ni or Co, M ′ is Al, Ni, Co, Cr, Fe, Mg , Sr, V, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu , Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr, at least one element selected from the group, M "is Al, Cr, Mn, Fe, Mg, Sr, V, Sc, Y , La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf , Es, Fm, Md, No, and at least one element selected from the group consisting of Lr, A is an element selected from the group consisting of O, F, S and P.) The method of claim 13, wherein the concentration of the metal, metal alkoxide, metal salt, or metal oxide in the metal organic solution or the metal aqueous solution is 0.1 to 50% by weight. The method of claim 15, wherein the concentration of the metal, metal alkoxide, metal salt or metal oxide in the metal organic solution or the metal aqueous solution is 1 to 20% by weight. The method of claim 13, wherein the metal organic solution or metal solution is one selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, and Zr. The manufacturing method of the positive electrode active material for lithium secondary batteries containing the above metal. The method of claim 13, wherein the metal organic solution or aqueous metal solution contains two or more metals. The method of claim 13, wherein the heat treatment is performed at 200 to 800 ° C. for 1 to 20 hours. The method of manufacturing a cathode active material for a lithium secondary battery according to claim 13, wherein the heat treatment step is performed in an atmosphere of flowing dry air. Primary coating the lithium compound with a metal organic solution or an aqueous metal solution; Primary heat treatment of the primary coated lithium compound to form a first metal oxide layer on the surface of the lithium compound; Second coating the lithium compound having the first metal oxide layer formed thereon with a metal organic solution or a metal aqueous solution, wherein the metal included in the metal organic solution or the metal aqueous solution is different from the metal of the first metal oxide layer; And Secondary heat treatment of the secondary coated lithium compound Including, A method of manufacturing a cathode active material for a lithium secondary battery, which is carried out by forming a second metal oxide layer on the first metal oxide layer. The method of claim 13, wherein the manufacturing method is performed by coating a metal organic solution or an aqueous metal solution and performing a heat treatment three or more times.

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