KR20120084585A - Cathod active material, method for preparing the same, lithium secondary battery comprising the same - Google Patents

Abstract

PURPOSE: A positive electrode active material, a manufacturing method thereof, and a lithium secondary battery including the same are provided to improve cycle properties, charging and discharging properties, and thermal stability. CONSTITUTION: A positive electrode active material for the lithium secondary battery comprises lithium composite metal oxide which is represented by the following chemical formula 1 : Li_aNi_xCo_yMn_zM_(1-x-y-z)O_(2-δ)Q_δ. The lithium compound metal oxide has a layered structure. The chemical formula 1 satisfies the following: 0.95ΔaΔ1.2, 0.6ΔxΔ0.8, 0.05ΔyΔ0.2, 5.0Δx/yΔ10.0, 2.0Δx/yΔ5.0, 0Δ|2y-z|Δ0.05, x≠y≠z, and 0Δ1-(x+y+z)Δ0.1. M is one or more elements selected from Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W and a combination thereof. Q is either a halogen element or S, and 0Δ δ Δ0.1.

Description

Cathode active material, a method of manufacturing the same, and a lithium secondary battery including the same TECHNICAL FIELD, LITHIUM SECONDARY BATTERY COMPRISING THE SAME

The present invention relates to a positive electrode active material for a lithium secondary battery, a method of manufacturing the same, and a lithium secondary battery including the same, and more particularly, to a positive electrode active material for a lithium secondary battery exhibiting improved thermal stability, a method of manufacturing the same, and a lithium secondary battery including the same. will be.

Recently, thanks to the rapid development of the electronics, telecommunications, and computer industries, the use of portable electronic products such as camcorders, mobile phones, notebook PCs, and the like, has increased the demand for light, long-lasting and reliable batteries.

In particular, the lithium secondary battery has an operating voltage of 3.7 V or more, and has a higher energy density per unit weight than a nickel-cadmium battery or a nickel-hydrogen battery. It is increasing day by day.

The lithium secondary battery is manufactured by using a material capable of reversible intercalation / deintercalation of lithium ions as a positive electrode and a negative electrode active material, and filling an organic electrolyte or a polymer electrolyte between the positive electrode and the negative electrode.

LiCoO ₂ , LiN _{1- x} M _x O ₂ (wherein x is 0.95 to 1 and M is Al, Co, Ni, Mn, or Fe) or LiMn ₂ O ₄ may be used as the cathode active material. _It is mainly used because of its high _divalent volumetric energy density, high temperature characteristics, in particular, cycle life characteristics at 60 ° C and swelling characteristics at 90 ° C.

However, there is still the requirement of stability with increasing capacity of the lithium secondary battery, in recent years, the Ni-containing more than 80% of _{Li [Ni 1 -x- y Co x} M y] that in order to have a high capacity characteristic O ₂ (1-xy> 0.8) and Li [Ni _x Co _1-2x Mn _x ] O ₂ , which is Ni-Co-Mn based on high capacity and thermal stability, has been actively studied. Although Li [Ni _1-xy Co _x M _y ] O ₂ (1-xy> 0.8) containing more than 80% of Ni has been studied in Japan to replace LiCoO ₂ , thermal stability with increasing Ni content There is difficulty in commercialization because it cannot solve the problem.

In _{addition, Li [Ni 1 -x- y Co} x M y] O 2 sealed _{Li [Ni 1/3 Co 1} /3 M 1/3] O 2 is Japanese Sanyo (Sanyo) Inc. are being commercialized by mixing LiCoO ₂ and . Since the material is configured to have an oxidation number in which Ni is divalent, Co is trivalent, and Mn is tetravalent, the thermal stability problem of the conventional Ni-based positive electrode active material can be solved, and Mn is filled / filled. It is also excellent in life characteristics because it is fixed to tetravalent during discharge.

_{However, Li [Ni 1/3 Co} 1/3 M 1/3] O 2 does not economical increase the Co content of the expensive price, a tap density of 2.5 to 2.7 about 1.8 to about 2.0 g / cc LiCoO ₂ Or, there was a problem lower than that of other positive electrode active materials.

An object of the present invention is to provide a cathode active material for a lithium secondary battery excellent in thermal stability in order to solve the above problems.

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

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

The present invention includes a lithium composite metal oxide represented by the following Chemical Formula 1 for the above purpose, the lithium composite metal oxide provides a cathode active material for a lithium secondary battery having a layered structure.

[Formula 1]

Li _a Ni _x Co _y Mn _z M _{1 -xy- z} O _{2 -δ} Q _δ

(In Formula 1, 0.95≤a≤1.2, 0.6≤x≤0.8, 0.05≤y≤0.2, 5.0≤x / y≤10.0, 2.0≤x / z≤5.0, 0≤│2y-z│≤0.05 , x ≠ y ≠ z, and 0≤1- (x + y + z) ≤0.1, where M is Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, At least one element selected from the group consisting of Nb, Ga, Sn, Mo, W, and combinations thereof, Q is a halogen element or S, and 0 ≦ δ ≦ 0.1)

The present invention also includes the steps of preparing a metal salt comprising nickel, metal salt comprising cobalt, manganese salt; When mole% of the amount of the metal salt containing nickel is A, mole% of the amount of the metal salt containing cobalt is B, and mole% of the amount of the metal salt containing manganese is C, said A, B, Mixing C satisfies the following formula: 0.6≤A≤0.8, 0.05≤B≤0.2, 5.0≤A / B≤10.0, 2.0≤A / C≤5.0, 0≤│2B-C│≤0.05; In an inert atmosphere, adding a mixed solution of the metal salt, a base and a chelating agent to the reactor and stirring to co-precipitate nickel, cobalt and manganese to prepare a metal hydroxide; Mixing the metal hydroxide and the lithium raw material at a molar ratio of 1: 1 to 1: 1.10 and performing a first heat treatment at a temperature increase rate of 2 to 10 ° C / min; And it provides a method for producing a cathode active material for a lithium secondary battery comprising the step of secondary heat treatment of the primary heat treatment product.

The present invention also includes a positive electrode comprising the positive electrode active material; Provided is a lithium secondary battery including a negative electrode including a negative electrode active material and a nonaqueous electrolyte.

The present invention relates to a cathode active material for a lithium secondary battery, a manufacturing method thereof, and a lithium secondary battery including the same. The lithium secondary battery including the cathode active material for a lithium secondary battery according to the present invention has excellent cycle characteristics and charge / discharge characteristics, and Thermal stability.

1 to 5 show the surface photographs of the final active material particles prepared in Examples 1 to 3 and Comparative Examples 1 and 2 by scanning electron microscope.
6 is a result of measuring XRD peaks of the final active material particles prepared in Examples 1 to 3 and Comparative Examples 1 and 2.
7 shows charge and discharge test results for batteries using the final active material particles prepared in Examples 1 to 3 and Comparative Examples 1 and 2. FIG.
Figure 8 shows the life characteristics test results for the battery using the final active material particles prepared in Examples 1 to 3 and Comparative Examples 1, 2.
9 shows test results using a differential scanning thermal analyzer for batteries using the final active material particles prepared in Examples 1 to 3 and Comparative Examples 1 and 2. FIG.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

The cathode active material according to an embodiment of the present invention includes a lithium composite metal oxide represented by the following Formula 1, and the lithium composite metal oxide has a layered structure.

[Formula 1]

Li _a Ni _x Co _y Mn _z M _{1 -xy- z} O _{2 -δ} Q _δ

(In Formula 1, 0.95≤a≤1.2, 0.6≤x≤0.8, 0.05≤y≤0.2, 5.0≤x / y≤10, 2.0≤x / z≤5.0, 0≤│2y-z│≤0.05 , x ≠ y ≠ z, and 0≤1- (x + y + z) ≤0.1, where M is Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, At least one element selected from the group consisting of Nb, Ga, Sn, Mo, W, and combinations thereof, Q is a halogen element or S, and 0 ≦ δ ≦ 0.1)

The positive electrode active material according to an embodiment of the present invention has a Ni content of 60 to 80%, a Co content of 5 to 20%, and a ratio of Ni to a Co content of 5 to 10, as shown in Formula 1 above. By adjusting the ratio of the Ni content to the Mn content to 2 to 5, and adjusting the contents of Ni, Co and Mn so that the ratio of the Mn content to the Co content is 0≤│2y-z│≤0.05, respectively, It contains a lot of high capacity while lowering the Co content to secure economic efficiency, it is possible to exhibit high thermal stability by adjusting the content of Ni, Co and Mn.

In the positive electrode active material according to an embodiment of the present invention, even if Ni to 60 to 80% for high capacity, the thermal stability is reduced when not controlling both the Co, Mn content as described above, consequently the life characteristics There may be a problem of this deterioration. That is, when the three elements other than lithium constituting the positive electrode active material are Mn, Co, and Ni, the desired thermal stability and high capacity can be obtained when the above range is satisfied, and any one of the three elements is different. If the element is changed to the desired effect is not obtained.

Another embodiment of the present invention relates to a method for producing the cathode active material.

The present invention first prepares a metal salt comprising nickel, a metal salt comprising cobalt, a metal salt comprising manganese, molar% of the amount of the metal salt containing nickel A, mol% of the amount of the metal salt containing cobalt When B and molar% of the amount of the metal salt containing manganese are referred to as C, A, B, and C are mixed so as to satisfy the following formula.

0.6≤A≤0.8, 0.05≤B≤0.2, 5.0≤A / B≤10, 2.0≤A / C≤5.0, 0≤│2B-C│≤0.05

The nickel raw material may be nickel sulfate, nickel hydroxide, nickel nitrate, nickel acetate or a mixture thereof, and the cobalt raw material may be cobalt sulfate, cobalt hydroxide, cobalt nitrate, cobalt acetate or Mixtures of these can be used. In addition, the manganese raw material may be used manganese sulfate, manganese hydroxide, manganese nitrate, manganese acetate or a mixture thereof.

The concentration of the prepared aqueous metal solution may be 1.5 to 3 M, and may be 1.8 to 2.4 M. When the concentration of the aqueous metal solution is included in the above range may have the advantage of obtaining an active material with improved spherical tap density.

Next, under an inert atmosphere, a mixed solution of the metal salt, a base and a chelating agent are added to the reactor and stirred to prepare a metal hydroxide by coprecipitation of nickel, cobalt and manganese.

As the base, an aqueous solution containing sodium hydroxide, potassium hydroxide or a combination thereof may be used to adjust pH while supplying a hydroxyl group in the coprecipitation step. At this time, the pH may be 10 to 12, may be 10.5 to 11.5. When the pH is in the above range, there is no problem that the metal of the particle melts again while an appropriate coprecipitation reaction can occur.

The chelating agent serves to help form the particles, for example, ammonia, ethylenediamine (NH ₂ CH ₂ CH ₂ NH ₂ ) or a combination thereof may be used.

The base is suitable to use a molar concentration of 1.8 to 2.2 times the molar concentration of the aqueous metal solution may cause an appropriate reaction, the chelating agent may be used in a molar concentration of 0.1 to 0.4 times the molar concentration of the aqueous metal solution It may also be used in a 0.2 to 0.3-fold molarity.

As the inert atmosphere, a nitrogen gas atmosphere or an argon gas atmosphere may be used.

It is also suitable for the aqueous metal solution to be added to the reactor at a rate of 0.2 to 1 liter / hour. Adding the aqueous metal solution at a rate in the above range has the effect of obtaining the resulting metal hydroxide in a constant form.

The aqueous metal solution, base and chelating agent are suitably added to the reactor at a temperature of 40 to 60 ° C.

When the temperature of the addition of the aqueous metal solution, the base and the chelating agent to the reactor is a temperature of 40 to 60 ℃, the effect of obtaining a particle of a constant size can be obtained.

Subsequently, the metal hydroxide and the lithium raw material are mixed in a molar ratio of 1: 1 to 1: 1.10. The metal hydroxide and the lithium raw material may be mixed in a molar ratio of 1: 1 to 1:05. When the mixing ratio of the metal hydroxide and the lithium raw material is included in the above range, the effect of high capacity and stable structure can be obtained. As the lithium raw material, lithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate, or a mixture thereof may be used.

The mixture is first heat treated (prebaked) at a rate of temperature increase of 2 to 10 ° C./min and the first heat treated product is subjected to a second heat treatment. At this time, the temperature increase rate may be 2 to 5 ℃ / min.

In addition, the first heat treatment process may be carried out at 450 to 500 ℃, the second heat treatment process may be carried out at 800 to 900 ℃. In addition, the primary heat treatment process may be performed for 5 to 10 hours, and the secondary heat treatment process may be performed for 5 to 20 hours.

When the temperature increase rate, the first heat treatment step, and the second heat treatment step are performed at the temperature and time ranges, a crystal structure is appropriately formed, so that insertion and desorption of lithium may occur easily.

In addition, the primary and secondary heat treatment may be carried out in a CO ₂ atmosphere, oxygen atmosphere or air atmosphere.

The positive electrode active material according to the embodiment of the present invention may be usefully used for the positive electrode of a lithium secondary battery. The lithium secondary battery includes a negative electrode and a nonaqueous electrolyte including a negative electrode active material together with a positive electrode.

The positive electrode is prepared by mixing a positive electrode active material, a conductive material, a binder, and a solvent according to an embodiment of the present invention to prepare a positive electrode active material composition, and then directly coating and drying the aluminum current collector. Alternatively, the cathode active material composition may be cast on a separate support, and then the film obtained by peeling from the support may be manufactured by laminating on an aluminum current collector.

The conductive material is carbon black, graphite, metal powder, the binder is vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene And mixtures thereof. In addition, N-methylpyrrolidone, acetone, tetrahydrofuran, decane, etc. are used as a solvent.

In this case, the contents of the positive electrode active material, the conductive material, the binder, and the solvent are used at levels commonly used in a lithium secondary battery.

Like the positive electrode, the negative electrode is mixed with a negative electrode active material, a binder, and a solvent to prepare an anode active material composition, and the negative electrode active material film coated on the copper current collector or cast on a separate support and peeled from the support is coated on the copper current collector. It is prepared by lamination. At this time, the negative electrode active material composition may further contain a conductive material if necessary.

As the negative electrode active material, a material capable of intercalating / deintercalating lithium is used, and for example, lithium metal, lithium alloy, coke, artificial graphite, natural graphite, organic polymer compound combustor, carbon fiber, or the like is used. . In addition, a conductive material, a binder, and a solvent are used similarly to the case of the positive electrode mentioned above.

The separator may be used as long as it is commonly used in lithium secondary batteries. For example, polyethylene, polypropylene, polyvinylidene fluoride or two or more multilayer films thereof may be used, and a polyethylene / polypropylene two-layer separator, It goes without saying that a mixed multilayer film such as polyethylene / polypropylene / polyethylene three-layer separator, polypropylene / polyethylene / polypropylene three-layer separator and the like can be used.

As the electrolyte to be charged in the lithium secondary battery, a non-aqueous electrolyte or a known solid electrolyte may be used, and a lithium salt is used.

Although the solvent of the said non-aqueous electrolyte is not specifically limited, Chain carbonate methyl acetate, ethyl acetate, such as cyclic carbonate dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, Esters such as propyl acetate, methyl propionate, ethyl propionate and γ-butyrolactone 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,2-dioxane, 2-methyltetrahydro Nitriles, such as ether acetonitrile, such as furan, or amides, such as dimethylformamide, etc. can be used. These can be used individually or in combination of two or more. In particular, a mixed solvent of a cyclic carbonate and a linear carbonate can be preferably used.

As the electrolyte, a gel polymer electrolyte in which an electrolyte solution is impregnated with a polymer electrolyte such as polyethylene oxide or polyacrylonitrile, or an inorganic solid electrolyte such as LiI or Li 3 N can be used.

The lithium salt is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , One selected from the group consisting of LiCl and LiI is possible.

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

≪ Example 1 >

4 liters of distilled water was added to the coprecipitation reactor (capacity 4L, output power of 80W or more), and nitrogen gas was supplied to the reactor at a rate of 0.5 liters / minute to remove dissolved oxygen and maintain the reactor temperature at 50 ° C at 1000 rpm. Stirred.

0.3M / hour aqueous metal solution of 2.4M concentration mixed with 65 mol%, 12 mol% and 23 mol% nickel sulfate, cobalt sulfate and manganese sulfate and 0.03 liter / hour It was added continuously. In addition, 4.8 mol of sodium hydroxide solution was supplied for pH adjustment so that the pH was maintained at 11. Impeller speed was adjusted to 1000 rpm. The flow rate was adjusted so that the average residence time of the solution in the reactor was about 6 hours. After the reaction reached a steady state, the reactant metal hydroxide was continuously obtained. The metal hydroxide was filtered, washed with water and dried in a 110 ° C. warm air dryer for 15 hours. After mixing the metal hydroxide and lithium hydroxide (LiOH) in a 1: 1.06 molar ratio, the first heat treatment at an elevated temperature rate of 2 ℃ / min in an air atmosphere and then maintained at 500 ℃ for 10 hours to perform the first heat treatment (preliminary firing) It was, subsequently under an air atmosphere, at a temperature of 850 ℃ 15 hours 2 primary heat treatment (sintering) to _{1 .06} Li (Ni Co _{0 .65 0 .12 0 .23} Mn) ₂ O to obtain a positive electrode active material powder.

Slurry was prepared by mixing a poly-vinylidene fluoride as a super-P and a binder as the prepared positive active material and the conductive material at a weight ratio of 85: 7.5: 7.5, respectively. This slurry was uniformly applied to an aluminum foil having a thickness of 20 μm, and vacuum dried at 120 ° C. to prepare a positive electrode.

The prepared anode and lithium foil were used as counter electrodes, and a porous polyethylene membrane (Celgard ELC, Celgrad 2300, thickness: 25 μm) was used as a separator, and ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1. LiPF ₆ in prepared solvent The coin battery was manufactured according to a commonly known manufacturing process using a liquid electrolyte dissolved at a concentration of 1 M.

<Example 2>

The same procedure as in Example 1, except that the aqueous solution of 2.4M concentration of a mixture of 70 mol% nickel sulfate, cobalt sulfate and manganese sulfate in 10 mol% and 20 mol% was added at 3 liters / hour Precursor particles were prepared. Thereafter, the Example 1 after the same manner as the lithium salt and mixing with the firing by _{1 .06} Li (Ni Co _{0 .70 0 .10 0 .20} Mn) ₂ O to obtain a positive electrode active material powder.

<Example 3>

The same procedure as in Example 1, except that the aqueous solution of 2.4M concentration of nickel, 75 mol%, cobalt sulfate and manganese sulfate was mixed in 8 mol% and 17 mol% was added at 3 liters / hour Precursor particles were prepared. Thereafter, the final Li _1.06 (Ni _0.75 Co _0.08 Mn _0.17 ) O ₂ positive electrode active material powder was obtained by mixing with a lithium salt and baking the same as in Example 1.

&Lt; Comparative Example 1 &

The same procedure as in Example 1 except that 55 mol% of nickel sulfate, cobalt sulfate and manganese sulfate were added at a rate of 3 liters / hour of an aqueous metal solution at a concentration of 2.4 M mixed with 15 mol% and 30 mol%. Precursor particles were prepared. Then, the final active material particles were obtained by mixing and baking with a lithium salt as in Example 1 above.

Comparative Example 2

The same procedure as in Example 1, except that the aqueous solution of 2.4M of metal mixed with 85 mol% nickel sulfate, cobalt sulfate and manganese sulfate in 5 mol% and 10 mol% was added at 3 liters / hour Precursor particles were prepared. Then, the final active material particles were obtained by mixing and baking with a lithium salt as in Example 1 above.

< Experimental Example  1: check the cross-sectional picture of the active material particles>

Surface photographs of the final active material particles prepared in Examples 1 to 3 and Comparative Examples were measured by a scanning electron microscope, and the results are shown in FIGS. 1 to 5. Each figure is a surface photograph measured by varying the magnification, and it can be seen that the particles are uniformly generated.

< Experimental Example  2: of active material particles XRD  OK>

XRD peaks of the final active material particles prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were measured, and the results are shown in FIG. 6.

< Experimental Example  3: Charging and discharging  Capacity, and cycle characteristic measurement>

Charge and discharge tests and cycle characteristics of the batteries using the active materials prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were measured, and the results are shown in FIGS. 7 and 8. The charging and discharging was performed 10 times for each sample under the condition of 0.2C between 2.7 and 4.3V, and the average value was taken. In addition, the charge and discharge characteristics and cycle characteristics results are summarized in Table 1 below.

Sample
LiOH 102% 0.2C
One ^st Discharge Capacity  (30 ^o C) One ^st Efficiency Cycle retention Example  One L651223 780 ^o C -15h 186.0 mAh / g 93.6% 97.5% (50 ^th ) Example  2 L701020 750 ^o C -15h 189.4 mAh / g 93.3% 86.8% (50 ^th ) Example  3 L750817 750 ^o C -15h 196.4 mAh / g 94 .7% Comparative example  One L551530 820 ^o C -15h 174.0 mAh / g 91.7% 99.4% (50 ^th ) Comparative example  2 L850510 730 ^o C -15h 192.6 mAh / g 87.6% 84.1% (50 ^th )

As shown in Table 1 and the following FIGS. 7 and 8, in the case of the secondary battery including the cathode active material of the present invention having a composition ratio of Ni, Co, and Mn according to the present invention, the secondary battery using the conventional active material is compared. When it did, it can confirm that cycling characteristics and a charge / discharge characteristic are more excellent.

< Experimental Example  4 : DSC  Through measurement Thermal stability  Evaluation>

10 ° C./min using a differential scanning thermal analyzer (DSC) in a state where 4.3 V of the positive electrode including each positive electrode active material prepared in Examples 1 to 3 and Comparative Example and the positive electrode including the positive electrode active material of Comparative Example were charged It was measured while heating up at a rate of, and the results are shown in FIG.

As shown in Figure 9, in the case of including the active material according to the invention it can be seen that the exothermic peak temperature in the DSC is 240 ℃ or more. That is, when using the positive electrode active material having a composition ratio of Ni, Co, Mn according to the present invention it can be seen that high thermal stability.

Claims (11)

To include a lithium composite metal oxide represented by the formula (1),
The lithium composite metal oxide has a layered structure positive electrode active material for a lithium secondary battery:
[Formula 1]
Li _a Ni _x Co _y Mn _z M _1-xyz O _2-δ Q _δ
(In Formula 1, 0.95≤a≤1.2, 0.6≤x≤0.8, 0.05≤y≤0.2, 5.0≤x / y≤10.0, 2.0≤x / y≤5.0, 0≤│2y-z│≤0.05 , x ≠ y ≠ z, and 0≤1- (x + y + z) ≤0.1, where M is Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, At least one element selected from the group consisting of Nb, Ga, Sn, Mo, W, and combinations thereof, Q is a halogen element or S, and 0 ≦ δ ≦ 0.1) The method of claim 1,
Average particle size of the active material is 10 ~ 15㎛ positive electrode active material. Preparing a metal salt comprising nickel, a metal salt comprising cobalt, and a metal salt comprising manganese;
When mole% of the amount of the metal salt containing nickel is A, mole% of the amount of the metal salt containing cobalt is B, and mole% of the amount of the metal salt containing manganese is C, said A, B, Mixing C to satisfy the following formula to prepare a metal aqueous solution;
0.6≤A≤0.8, 0.1≤B≤0.2, 5.0≤A / B≤10, 2≤A / C≤5, 0≤│2B-C│≤0.05
In an inert atmosphere, adding a metal aqueous solution of the mixed metal salt, a base, and a chelating agent to the reactor and stirring to co-precipitate nickel, cobalt and manganese to prepare a metal hydroxide;
Mixing the metal hydroxide and the lithium raw material at a molar ratio of 1: 1 to 1: 1.10 and performing a first heat treatment at a temperature increase rate of 2 to 10 ° C / min; And
Method of manufacturing a positive electrode active material for a lithium secondary battery comprising the step of secondary heat treatment of the primary heat treatment product. The method of claim 3,
The concentration of the aqueous metal solution is 1.5 to 3M. The method of claim 3,
The base is an aqueous solution containing a compound selected from the group consisting of sodium hydroxide, potassium hydroxide and combinations thereof. The method of claim 3,
The metal aqueous solution is added to the reactor at a rate of 0.2 to 1 liter / hour. The method of claim 3,
The aqueous metal solution, base and chelating agent are added to the reactor at a temperature of 40 to 60 ℃. The method of claim 3,
The primary heat treatment is carried out at 450 to 500 ° C. The method of claim 3,
The secondary heat treatment is performed at 800 to 900 ° C. A lithium secondary battery comprising the cathode active material according to claim 1. The method of claim 10,
A lithium secondary battery having an exothermic peak temperature of 240 ° C. or more by differential scanning thermal analysis in a 4.3 V state of charge of a lithium secondary battery including the cathode active material.

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