Positive electrode active material, method for manufacturing the same, and positive electrode and lithium secondary battery containing the same

Abstract

This invention relates to a positive electrode active material in single-particle form, and the average particle size (D 50 The present invention relates to a lithium composite transition metal oxide in single-particle form having a particle size greater than 5.5 μm and less than or equal to 10.0 μm, wherein the lithium composite transition metal oxide is a positive electrode active material containing Al, Y, and Zr, a method for producing the same, and a positive electrode and lithium secondary battery containing the same.

Description

[Technical Field]

[0001] This application claims priority under Korean Patent Application No. 10-2023-0047005 dated April 10, 2023, and all content disclosed in the said Korean Patent Application is incorporated herein by reference.

[0002] The present invention relates to a positive electrode active material comprising a lithium composite transition metal oxide in single-particle form, a method for producing the same, and a positive electrode and lithium secondary battery containing the same. [Background technology]

[0003] Recently, in order to solve the structural and thermal stability problems of secondary particle cathode materials themselves, the development of single-particle cathode materials has been accelerating.

[0004] Specifically, when secondary particle-type cathode materials are applied to lithium-ion batteries, the large surface area in contact with the electrolyte causes a large amount of gas to be generated, leading to an expansion of the battery's volume. Furthermore, increasing the nickel content in the cathode material to achieve high capacity also increases the risk of fire. Therefore, there is a growing need for the development of single-particle-type cathode materials.

[0005] On the other hand, while single-particle cathode materials show improvements in structural and thermal stability compared to secondary-particle cathode materials, stability remains a problem when increasing the nickel content in the cathode material for higher capacity.

[0006] Therefore, there is a need to develop single-particle cathode materials that offer excellent stability and can improve battery capacity retention and thermal stability when applied to batteries. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to solve the above-mentioned problems and provides a positive electrode active material containing a single-particle lithium composite transition metal oxide that has excellent structural stability and can improve the battery's capacity retention rate, thermal stability, etc., when applied to a battery.

[0008] Furthermore, the present invention aims to provide a method for producing the positive electrode active material.

[0009] Furthermore, the present invention aims to provide a lithium secondary battery that includes the positive electrode active material and has improved capacity retention rate, thermal stability, and other properties. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides a positive electrode active material, a method for producing a positive electrode active material, a positive electrode, and a lithium secondary battery.

[0011] (1) The present invention relates to the average particle size (D 50 The present invention provides a positive electrode active material comprising a lithium composite transition metal oxide in single-particle form having a diameter greater than 5.5 μm and less than or equal to 10.0 μm, wherein the lithium composite transition metal oxide contains Al, Y, and Zr.

[0012] (2) The present invention provides a positive electrode active material in which, in the present invention, Al is contained in an amount of 500 ppm to 3,000 ppm relative to the total weight of the lithium composite transition metal oxide.

[0013] (3) The present invention provides a positive electrode active material in which, in (1) or (2) above, Y is contained in an amount of 100 ppm to 2,000 ppm relative to the total weight of the lithium composite transition metal oxide.

[0014] (4) The present invention provides a positive electrode active material in which, in any one of (1) to (3) above, the Zr is contained in an amount of 500 ppm to 5,000 ppm relative to the total weight of the lithium composite transition metal oxide.

[0015] (5) In any one of the above (1) to (4), the present invention provides a cathode active material in which the lithium composite transition metal oxide contains 60 mol% or more of nickel based on the total molar amount of metals other than lithium.

[0016] (6) In any one of the above (1) to (5), the present invention provides a cathode active material in which the lithium composite transition metal oxide has a composition represented by the following Chemical Formula 1. [Chemical Formula 1] Li x [Ni a Co b Mn c Al d Y e Zr f M1 g O 2-y A y In Chemical Formula 1 above, M1 is one or more selected from B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca, A is one or more selected from F, Cl, Br, I, and S, 0.9 ≤ x ≤ 1.2, 0.6 ≤ a < 1, 0 ≤ b ≤ 0.4, 0 ≤ c ≤ 0.4, 0 < d ≤ 0.01, 0 < e ≤ 0.0006, 0 < f ≤ 0.005, 0 ≤ g ≤ 0.2, a + b + c + d + e + f + g = 1, 0 ≤ y ≤ 0.2.

[0017] (7) In any one of the above (1) to (6), the present invention provides a cathode active material further including a coating portion containing Co formed on the lithium composite transition metal oxide in the single particle form. <00002\99> (8) In the above (7), the present invention provides a cathode active material in which the coating portion further includes Al, Zr, or a combination thereof as well.

[0019] (9) The present invention provides a method for producing a positive electrode active material, comprising the steps of (A) mixing a positive electrode active material precursor which is a composite transition metal hydroxide, a composite transition metal oxyhydroxide or a combination thereof, a first lithium-containing raw material, an aluminum-containing raw material, a yttrium-containing raw material, and a zirconium-containing raw material to produce a mixture; (B) primary firing of the mixture at a temperature of 820°C to 950°C to produce a primary fired product; and (C) selectively mixing a second lithium-containing raw material with the primary fired product, and then secondary firing at a temperature of 700°C to 850°C to produce a secondary fired product.

[0020] (10) The present invention provides a method for producing a positive electrode active material, further comprising the step of (B') grinding the primary calcined product before step (C) in (9).

[0021] (11) The present invention provides a method for producing a positive electrode active material, further comprising the step of (C') pulverizing the secondary calcined product in (9) or (10) above.

[0022] (12) The present invention provides a method for producing a positive electrode active material, further comprising the step of (D) mixing the secondary calcined product with a cobalt-containing coating material and then heat-treating it, in any one of the above (9) to (11).

[0023] (13) The present invention provides a method for producing a positive electrode active material, wherein in step (D) of (12), when mixing the secondary calcined product with the cobalt-containing coating material, an aluminum-containing coating material, a zirconium-containing coating material, or a combination thereof is further mixed.

[0024] (14) The present invention provides a method for producing a positive electrode active material, wherein, in (12) or (13) above, the cobalt-containing coating material is mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the secondary calcined product (A) is 0.01 to 0.03.

[0025] (15) The present invention provides a method for producing a positive electrode active material in which, in (13) above, the aluminum-containing coating material is mixed in an amount of 0.03 to 0.10 parts by weight per 100 parts by weight of the secondary calcined product.

[0026] (16) The present invention provides a method for producing a positive electrode active material in any one of (12) to (15) above, wherein the heat treatment is performed in an oxygen atmosphere.

[0027] (17) The present invention provides a method for producing a positive electrode active material in any one of the above (12) to (16), wherein the heat treatment is performed at a temperature of 600°C to 800°C.

[0028] (18) The present invention provides a positive electrode comprising a positive electrode active material according to any one of (1) to (8) above.

[0029] (19) The present invention provides a lithium secondary battery comprising a positive electrode according to (18), a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. [Effects of the Invention]

[0030] The positive electrode active material of the present invention has an average particle size (D 50 The material contains a lithium composite transition metal oxide in single-particle form with a particle size greater than 5.5 μm and less than or equal to 10.0 μm, wherein the lithium composite transition metal oxide contains Al, Y, and Zr, and can improve the capacity characteristics, life characteristics, etc., of lithium secondary batteries.

[0031] Furthermore, the method for producing the positive electrode active material of the present invention makes it possible to effectively produce the above-mentioned positive electrode active material. [Brief explanation of the drawing]

[0032] [Figure 1] This is the TEM EDX-Mapping data for the positive electrode active material of Example 1. [Modes for carrying out the invention]

[0033] The present invention will be described in more detail below to facilitate understanding of it.

[0034] The terms and words used herein and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may define the concepts of terms as appropriate to best describe their invention.

[0035] In this specification, terms such as “includes,” “equip,” or “have” indicate the presence of implemented features, figures, steps, components, or combinations thereof, but should be understood not to preclude the existence or possibility of adding one or more different features, figures, steps, components, or combinations thereof.

[0036] In this specification, the term “on top of” means not only when one configuration is formed directly on top of another, but also when a third configuration is interposed between these configurations.

[0037] In this specification, "single-particle positive electrode active material" is a concept contrasted with positive electrode active material in the form of spherical secondary particles formed by the aggregation of tens to hundreds of primary particles manufactured by conventional methods, and refers to a positive electrode active material consisting of 10 or fewer primary particles. Specifically, in the present invention, the single-particle positive electrode active material may be a single particle consisting of one primary particle, or it may be a secondary particle form formed by the aggregation of several primary particles.

[0038] "Primary particles" refer to the smallest particle units that can be recognized when observing the positive electrode active material through a scanning electron microscope, while "secondary particles" refer to secondary structures formed by the aggregation of multiple primary particles.

[0039] In this specification, the term "average particle size (D)" is used. 50)" refers to the particle size at the 50% point of the cumulative volume distribution by particle size. The average particle size is calculated by dispersing the powder to be measured in a dispersion medium, introducing it into a commercially available laser diffraction particle size analyzer (for example, Microtrac's S3500), measuring the difference in diffraction patterns due to particle size as the particles pass through the laser beam to calculate the particle size distribution, and then calculating the particle size at the point where the cumulative volume distribution by particle size in the measuring device reaches 50%. 50 It can be measured.

[0040] positive electrode active material This invention relates to the average particle size (D 50 The material comprises a lithium composite transition metal oxide in single-particle form having a diameter greater than 5.5 μm and less than or equal to 10.0 μm, wherein the lithium composite transition metal oxide provides a positive electrode active material containing Al, Y, and Zr. The lithium composite transition metal oxide may have a layered structure.

[0041] The inventors have found that the positive electrode active material has an average particle size (D 50 The inventors have discovered that when a lithium composite transition metal oxide in single-particle form has a particle size greater than 5.5 μm and less than or equal to 10.0 μm, and the lithium composite transition metal oxide contains Al, Y, and Zr as dopants, the structural stability of the positive electrode active material increases, cation mixing decreases, and the grain size becomes large, approximately 3.5 μm to 7.0 μm, thereby improving the capacity characteristics and life characteristics of lithium secondary batteries, and have completed the present invention. Specifically, the inventors have found that in order to improve the structural stability of a positive electrode active material in single-particle form with a large average particle size, Zr and Al are included as dopants. When Al is included as a dopant, there is a problem that the grain size does not increase, but to solve this, the inventors have completed the present invention by simultaneously including Y.

[0042] According to the present invention, the lithium composite transition metal oxide in single-particle form has an average particle size (D 50The average particle size (D) of the lithium composite transition metal oxide in single-particle form may be, specifically, greater than 5.5 μm, 6.0 μm or more, 6.5 μm or more, 7.0 μm or less, 7.5 μm or less, 8.0 μm or less, 8.5 μm or less, 9.0 μm or less, 9.5 μm or less, or 10.0 μm or less. The average particle size (D) of the lithium composite transition metal oxide is greater than 5.5 μm and 10.0 μm or less. 50 When the coefficient of flux (θ) is within the aforementioned range, the specific surface area decreases and contact with the electrolyte is reduced. Therefore, a battery containing the positive electrode active material according to the present invention has the advantages of high capacity retention, reduced gas generation, and excellent thermal stability.

[0043] On the other hand, the average particle size (D) of the lithium composite transition metal oxide 50 If the particle size is 5.5 μm or less, the specific surface area increases due to the small particle size, resulting in problems with the battery's capacity retention rate and thermal stability. If the particle size is greater than 10.0 μm, the lithium travels a longer distance within the particle, increasing resistance and reducing charging capacity.

[0044] According to the present invention, the Al can be included in an amount of 500 ppm to 3,000 ppm relative to the total weight of the lithium composite transition metal oxide. In this case, the crystal structure inside the positive electrode active material is stabilized, and the capacity characteristics and resistance characteristics of the battery can be improved.

[0045] According to the present invention, Y can be included in an amount of 100 ppm to 2,000 ppm relative to the total weight of the lithium composite transition metal oxide. In this case, the grain size contained in each particle is approximately 3.5 μm to 7.0 μm, which can improve the capacity characteristics and lifespan characteristics of the battery.

[0046] According to the present invention, the Zr can be included in an amount of 500 ppm to 5,000 ppm relative to the total weight of the lithium composite transition metal oxide. In this case, the Zr is stably doped into the lithium layer, and structural stability is improved during lithium insertion and removal, thereby improving the battery's lifespan and resistance characteristics.

[0047] According to the present invention, the lithium composite transition metal oxide may contain 60 mol% or more, specifically 80 mol% or more, and more specifically 85 mol% or more, of nickel relative to the total number of moles of metals other than lithium. In other words, the lithium composite transition metal oxide may be a high-nickel (High Ni) lithium composite transition metal oxide. In this case, the energy density of the lithium secondary battery can be improved.

[0048] According to the present invention, the lithium composite transition metal oxide may have a composition represented by the following chemical formula 1. In this case, the lithium composite transition metal oxide has a layered structure.

[0049] [Chemical formula 1] Li x [Ni a Co b Mn c Al d Y e Zr f M1 g ]O 2-y A y

[0050] In the aforementioned chemical formula 1, M1 is one or more elements selected from B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca. A is one or more elements selected from F, Cl, Br, I, and S. 0.9≦x≦1.2, 0.6≦a<1, 0≦b≦0.4, 0≦c≦0.4, 0 <d≦0.01、0<e≦0.0006、0<f≦0.005、0≦g≦0.2、a+b+c+d+e+f+g=1、0≦y≦0.2である。

[0051] The a above-mentioned a represents the atomic fraction of nickel among the metal elements in the lithium composite transition metal oxide, and may be 0.6 ≤ a < 1, 0.8 ≤ a ≤ 0.98, or 0.85 ≤ a ≤ 0.95.

[0052] The value of b above means the atomic fraction of cobalt among the metal elements in the lithium composite transition metal oxide, and may be 0 ≤ b ≤ 0.4, 0.01 ≤ b ≤ 0.2, or 0.01 ≤ b ≤ 0.15.

[0053] The value of c refers to the atomic fraction of manganese among the metal elements in the lithium composite transition metal oxide, and may be 0 ≤ c ≤ 0.4, 0.01 ≤ c ≤ 0.2, or 0.01 ≤ c ≤ 0.15.

[0054] The above d represents the atomic fraction of aluminum among the metal elements in the lithium composite transition metal oxide, and 0 <d≦0.01、0.002≦d≦0.008または0.003≦d≦0.006であってもよい。

[0055] The aforementioned e represents the atomic fraction of yttrium among the metal elements in the lithium composite transition metal oxide, and 0 <e≦0.0006、0.0001≦e≦0.0005または0.0002≦e≦0.0003であってもよい。

[0056] The aforementioned f represents the atomic fraction of zirconium among the metal elements in the lithium composite transition metal oxide, and 0 <f≦0.005、0.001≦f≦0.003または0.001≦f≦0.002であってもよい。

[0057] The value of g refers to the atomic fraction of element M1 among the metal elements in the lithium composite transition metal oxide, and may be 0 ≤ g ≤ 0.2, 0 ≤ g ≤ 0.1, or 0 ≤ g ≤ 0.05.

[0058] According to the present invention, the positive electrode active material may further include a coating portion containing Co formed on the single-particle lithium composite transition metal oxide. The coating portion may further include Al, Zr, or a combination thereof. When the positive electrode active material further includes the coating portion, the amount of residual lithium by-products can be reduced, structural stability can be increased, the battery life characteristics and resistance characteristics can be improved, and the amount of gas generated can also be reduced. Here, the coating portion may be in the form of a thin film and may be formed over the entire lithium composite transition metal oxide or locally.

[0059] The Co present in the coating portion may be present in an amount of 0.5 mol% to 3 mol% relative to the total number of moles of metals other than lithium contained in the lithium composite transition metal oxide. In this case, residual lithium by-products can be further reduced, and the lifespan and resistance characteristics can be further improved.

[0060] The Al present in the coating portion may be contained in an amount of 300 ppm to 10,000 ppm relative to the total weight of the lithium composite transition metal oxide. In this case, structural stability is further enhanced, and life characteristics, resistance characteristics, and other properties can be further improved.

[0061] Method for manufacturing positive electrode active material The present invention provides a method for producing the positive electrode active material described above. Specifically, the positive electrode active material according to the present invention is produced by the following method for producing the positive electrode active material.

[0062] The method for producing a positive electrode active material according to the present invention includes the steps of: (A) mixing a positive electrode active material precursor which is a composite transition metal hydroxide, a composite transition metal oxyhydroxide or a combination thereof, a first lithium-containing raw material, an aluminum-containing raw material, a yttrium-containing raw material, and a zirconium-containing raw material to produce a mixture; (B) primary firing of the mixture at a temperature of 820°C to 950°C to produce a primary fired product; and (C) selectively mixing a second lithium-containing raw material with the primary fired product, and then secondary firing at a temperature of 700°C to 850°C to produce a secondary fired product.

[0063] The aluminum-containing raw material may be one or more selected from Al(OH)3, Al2O3, AlCl3, Al(NO)3, AlSO4, and Al2S3, and more specifically, one or more selected from Al(OH)3, Al2O3, and Al(NO)3, and more specifically, Al(OH)3. The aluminum-containing raw material can be added in an amount of 500 ppm to 3,000 ppm relative to the total weight of the positive electrode active material precursor.

[0064] The yttrium-containing raw material may be one or more selected from YCl3, Y2O3, Y(NO3)3, Y(OH)3, YSZ, Y2(SO4)3, and Y2S3, and more specifically, one or more selected from Y2O3 and Y(OH)3, and more specifically, Y2O3. The yttrium-containing raw material may be added in an amount of 100 ppm to 2000 ppm relative to the total weight of the positive electrode active material precursor.

[0065] The aforementioned zirconium-containing raw material is Zr(OH)4, ZrO2, Zr(NO3)4, ZrCl4, ZrS2, Zr(SO4)2, and C8H 12 It may be one or more selected from O8Zr, specifically one or more selected from Zr(OH)4 and ZrO2, and more specifically ZrO2. The zirconium-containing raw material can be added in an amount of 500 ppm to 5000 ppm relative to the total weight of the positive electrode active material precursor.

[0066] When the mixture is subjected to primary calcination at a temperature of 820°C to 950°C, the primary particles of the positive electrode active material precursor aggregate to produce a primary calcined product in the form of single particles.

[0067] When the primary firing temperature is within the aforementioned range, the primary particles of the positive electrode active material precursor aggregate to form a structurally stable single-particle primary firing product. However, when the primary firing temperature is below 820°C, there is a problem that the primary particles do not aggregate sufficiently, and when it exceeds 950°C, there is a problem that a structurally unstable firing product with low crystallinity is produced.

[0068] According to the present invention, the primary calcination can be carried out under an oxygen atmosphere in order to prevent the lithium transition metal oxide from degenerating into a rock salt structure.

[0069] According to the present invention, the primary firing can be carried out for 3 to 12 hours, specifically 6 to 12 hours, and more specifically 9 to 12 hours, in order to aggregate the primary particles and improve the crystallinity of the primary fired product.

[0070] When the primary-fired product is subjected to secondary firing at a temperature of 700°C to 850°C, lithium is inserted into the primary-fired product, producing a secondary-fired product. Here, the secondary-fired product is a lithium composite transition metal oxide in single-particle form.

[0071] When the secondary firing temperature is within the aforementioned range, lithium is inserted into the rock salt structure that may form on the surface of the primary fired product due to the high temperature during primary firing, restoring it to a layered structure and reducing lithium by-products. On the other hand, when the secondary firing temperature is below 700°C, there is a problem that the lithium insertion rate is slow due to the low temperature, and when it exceeds 850°C, there is a problem that the surface of the primary fired product degenerates into a rock salt structure due to the high temperature, leaving behind lithium by-products.

[0072] According to the present invention, the secondary calcination can be carried out under an oxygen atmosphere in order to prevent the lithium transition metal oxide from degenerating into a rock salt structure.

[0073] According to the present invention, the secondary firing can be performed for 3 to 12 hours, specifically 6 to 12 hours, or more specifically 9 to 12 hours, in order to increase the degree of crystallinity of the crystal structure inside the positive electrode active material.

[0074] The method for producing a positive electrode active material according to the present invention may further include, before step (C), step (B') of grinding the primary calcined product. Step (B') involves grinding the primary calcined product to an average particle size (D 50 The material can be ground so that the particles are between 5.5 μm and 10.0 μm.

[0075] The method for producing a positive electrode active material according to the present invention may further include the step of (C') grinding the secondary calcined product. The step of (C') grinds the primary calcined product to an average particle size (D 50 The material can be ground so that the particles are between 5.5 μm and 10.0 μm.

[0076] The grinding in steps (B') and (C') above can be carried out using a pin mill, ACM, jet mill, etc. On the other hand, the pin mill can be used at 18,000 rpm, the ACM can be used with Hosokawa equipment at 6,000 rpm for classification and 12,000 rpm for grinding, and the jet mill can be used with ZM Solution equipment at a grinding pressure of 6 bar and 3,500 rpm for classification.

[0077] The positive electrode active material according to the present invention can be manufactured by a process in which the lithium-containing raw material is added in two stages, or by a process in which it is added in one stage. That is, the lithium-containing raw material may be added all at once before the primary calcination, or it may be added in two stages, before the primary calcination and before the secondary calcination, respectively.

[0078] When the lithium-containing raw material is added in two separate steps, the positive electrode active material according to the present invention is obtained by, for example, primary calcining the mixture produced in step (A) at a temperature of 820°C to 950°C to obtain a primary calcined product, and then reducing the average particle size (D) of the primary calcined product at room temperature. 50 The material is ground to a particle size greater than 5.5 μm and less than or equal to 10.0 μm, the ground primary calcined product is mixed with the second lithium-containing raw material, and the secondary calcined product is obtained by secondary calcination at a temperature of 700°C to 850°C, and the secondary calcined product is then subjected to an average particle size (D) test at room temperature. 50 ) can be manufactured by grinding so that the particles are greater than 5.5 μm and less than or equal to 10.0 μm. Here, in step (A), the first lithium-containing raw material can be mixed so that the ratio (M:Li) of the total number of moles of transition metal (M) contained in the positive electrode active material precursor to the number of moles of lithium (Li) contained in the first lithium-containing raw material is 1:0.95 to 1:1.02, and in step (C), the second lithium-containing raw material can be mixed so that the ratio (M:Li) of the total number of moles of transition metal (M) contained in the positive electrode active material precursor in step (A) to the number of moles of lithium (Li) contained in the second lithium-containing raw material is 1:0.01 to 1:1.10.

[0079] When the lithium-containing raw material is added all at once, the positive electrode active material according to the present invention is, for example, prepared by first firing the mixture produced in step (A) at a temperature of 820°C to 950°C, then immediately cooling it down to 700°C to 850°C (without cooling it down to room temperature), and then second firing it at a temperature of 700°C to 850°C to obtain a second firing product, and then drying the second firing product at room temperature to obtain an average particle size (D 50 ) can be manufactured by grinding so that the particles are greater than 5.5 μm and less than or equal to 10.0 μm. Here, in step (A), the first lithium-containing raw material can be mixed so that the ratio (M:Li) of the total number of moles of transition metal (M) contained in the positive electrode active material precursor to the number of moles of lithium (Li) contained in the first lithium-containing raw material is 1:1.00 to 1:1.10. Also, the primary firing temperature can be higher than the secondary firing temperature.

[0080] The method for producing a positive electrode active material according to the present invention may further include the step of (D) mixing the secondary calcined product with a cobalt-containing coating material and then heat-treating it. In this case, a coating portion containing Co is formed on the secondary calcined product (a lithium composite transition metal oxide in single-particle form).

[0081] According to the present invention, in step (D), when mixing the secondary fired product with the cobalt-containing coating material, an aluminum-containing coating material, a zirconium-containing coating material, or a combination thereof may be further mixed. In this case, the coating portion may further contain Al, Zr, or a combination thereof, in addition to Co.

[0082] According to the present invention, the cobalt-containing coating material can be mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the secondary calcined product (A) is 0.01 to 0.03. In this case, there is an advantage that lithium by-products can be controlled in the manufacturing process of the positive electrode active material, which does not include a water washing step.

[0083] The cobalt-containing coating material may be one or more selected from Co(OH)2, Co3O4, CoO, (CH3CO2)2Co, CoCl2, and CoSO4·xH2O, and specifically may be Co(OH)2.

[0084] According to the present invention, the aluminum-containing coating material can be mixed in an amount of 0.03 to 0.10 parts by weight per 100 parts by weight of the secondary firing product. In this case, structural stability can be ensured, thereby improving lifespan, resistance, and gas generation.

[0085] The aluminum-containing coating material may be one or more selected from Al(OH)3, Al2(SO4)3·xH2O, Al2O3, Al(NO3)3·9H2O, AlCl3, and C2H5O4Al, and specifically may be Al(OH)3.

[0086] The zirconium-containing coating material is Zr(OH)4, ZrO2, Zr(NO3)4, ZrCl4, ZrS2, Zr(SO4)2, and C8H 12 It may be one or more selected from O8Zr.

[0087] According to the present invention, the heat treatment can be carried out under an oxygen atmosphere to prevent the lithium transition metal oxide from degenerating into a rock salt structure.

[0088] According to the present invention, the heat treatment can be performed at a temperature of 600°C to 800°C, specifically 650°C to 780°C, and more specifically 680°C to 720°C, in order to form the coating portion to an appropriate thickness.

[0089] According to the present invention, the heat treatment can be performed for 1 to 10 hours, specifically 2 to 8 hours, and more specifically 3 to 6 hours, in order to increase the degree of crystallinity of the coated portion.

[0090] positive electrode The present invention provides a positive electrode containing the positive electrode active material.

[0091] The positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer may include the positive electrode active material.

[0092] The positive electrode current collector is not particularly limited as long as it contains a highly conductive metal, allows for easy adhesion of the positive electrode active material layer, and is unreactive within the battery voltage range. Examples of materials that can be used for the positive electrode current collector include stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with surface treatments such as carbon, nickel, titanium, or silver. Furthermore, the positive electrode current collector can typically have a thickness of 3 μm to 500 μm, and fine irregularities can be formed on the surface of the current collector to enhance the adhesion of the positive electrode active material. It can be used in various forms, such as films, sheets, foils, meshes, porous materials, foams, and nonwoven fabrics.

[0093] The positive electrode active material layer may optionally contain a conductive material and a binder along with the positive electrode active material. Here, the positive electrode active material can be included in an amount of 80% to 99% by weight, more specifically 85% to 98.5% by weight, relative to the total weight of the positive electrode active material layer, and within this range, excellent capacitance characteristics can be observed.

[0094] The conductive material is used to impart conductivity to the electrodes and can be used without particular limitations in a battery that does not cause chemical changes and possesses electronic conductivity. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. Of these, one or more can be used. The conductive material can be included in an amount of 0.1% to 15% by weight relative to the total weight of the positive electrode active material layer.

[0095] The binder plays a role in improving the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, and polymers in which the hydrogen atoms of these materials are substituted with Li, Na, or Ca, or various copolymers thereof. One of these materials alone or a mixture of two or more materials can be used. The binder can be present in an amount of 0.1% to 15% by weight relative to the total weight of the positive electrode active material layer.

[0096] The positive electrode can be manufactured by a conventional method for manufacturing a positive electrode, except that the positive electrode active material is used. Specifically, the positive electrode can be manufactured by coating a positive electrode active material layer-forming composition, which is prepared by dissolving or dispersing the positive electrode active material and, if necessary, selectively, a binder, a conductive material, and a dispersant in a solvent, onto a positive electrode current collector, followed by drying and rolling; or by casting the positive electrode active material layer-forming composition onto another support, peeling it off the support, and laminating the resulting film onto the positive electrode current collector.

[0097] The solvent may be any solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water, and one or more of these can be used individually or in mixtures of two or more. The amount of solvent used should be sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant, taking into consideration the coating thickness of the slurry and the manufacturing yield, and to have a viscosity that allows for excellent thickness uniformity when applied for the manufacture of the positive electrode.

[0098] Lithium-ion battery The present invention provides a lithium secondary battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte.

[0099] The lithium secondary battery may optionally further include a battery container for housing the electrode assembly comprising the positive electrode, negative electrode, and separator, and a sealing member for sealing the battery container.

[0100] The negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0101] The negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloys can be used. The negative electrode current collector can usually have a thickness of 3 μm to 500 μm, and, similar to the positive electrode current collector, fine irregularities can be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material. For example, it can be used in various forms such as film, sheet, foil, mesh, porous material, foam, and nonwoven fabric.

[0102] The negative electrode active material layer may selectively include a binder and a conductive material together with the negative electrode active material.

[0103] As the negative electrode active material, compounds capable of reversible intercalation and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO2. β Examples include metallic oxides that can be doped and dedoped with lithium, such as (0<β<2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites containing the metallic compound and carbonaceous material, such as Si-C composites or Sn-C composites; and any one or more mixtures thereof can be used. A metallic lithium thin film can also be used as the negative electrode active material. Furthermore, both low-crystallinity carbon and high-crystallinity carbon can be used as the carbon material. Typical low-crystalline carbons include soft carbon and hard carbon, while typical high-crystalline carbons include amorphous, plate-like, flaky, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbons such as petroleum or coal tar pitch-derived cokes. The anode active material can be present in an amount of 80% to 99% by weight relative to the total weight of the anode active material layer.

[0104] The binder in the negative electrode active material layer is a component that helps to bond the conductive material, active material, and current collector, and is usually added in an amount of 0.1% to 10% by weight relative to the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0105] The conductive material in the negative electrode active material layer is a component for further improving the conductivity of the negative electrode active material, and can be added in an amount of 10% by weight or less, preferably 5% by weight or less, relative to the total weight of the negative electrode active material layer. Such conductive materials are not particularly limited as long as they do not cause chemical changes in the battery and are conductive, and examples of usable materials include graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0106] The negative electrode can be manufactured by coating a negative electrode active material layer-forming composition, which is prepared by dissolving or dispersing a negative electrode active material and a binder and conductive material selectively in a solvent, onto a negative electrode current collector and then drying it, or by casting the negative electrode active material layer-forming composition onto another support, peeling it off the support, and then laminating the resulting film onto the negative electrode current collector.

[0107] The separator separates the negative and positive electrodes and provides a passage for lithium ions to move. It can be used without particular limitations as long as it is a separator typically used in lithium secondary batteries. Particularly preferred is one that exhibits low resistance to electrolyte ion movement and excellent electrolyte impregnation ability. Specifically, porous polymer films, such as those made from polyolefin polymers like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or laminated structures of two or more layers thereof, can be used. Alternatively, ordinary porous nonwoven fabrics, such as those made from high-melting-point glass fibers or polyethylene terephthalate fibers, can also be used. Furthermore, coated separators containing ceramic components or polymeric substances can be used to ensure heat resistance or mechanical strength, and can be selectively used as single-layer or multi-layer structures.

[0108] Examples of the electrolyte include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries. Specifically, the electrolyte may contain an organic solvent and a lithium salt.

[0109] The organic solvent can be used without particular limitations, as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvents include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (propylene Carbonate solvents such as carbonate (PC); alcoholic solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, and can include a double-bonded aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, carbonate solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge and discharge performance of the battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred.

[0110] The lithium salt can be used without particular limitations as long as it is a compound that can provide lithium ions for use in lithium secondary batteries. Specifically, the anion of the lithium salt is F - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - The lithium salt may be selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. The concentration of the lithium salt is preferably in the range of 0.1M to 2.0M. When the concentration of the lithium salt is within this range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0111] In addition to the components of the electrolyte, the electrolyte may also contain one or more additives, such as haloalkylene carbonate compounds like difluoroethylene carbonate, pyridine, triethyl phosphite, triethyl alcoholamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethyl alcohol, or aluminum trichloride, for purposes such as improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity. Here, the additive may be present in an amount of 0.1% to 5% by weight relative to the total weight of the electrolyte.

[0112] The lithium secondary battery containing the positive electrode active material according to the present invention exhibits excellent capacity characteristics and excellent lifespan characteristics, making it useful in portable devices such as mobile phones, notebook computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0113] The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, rectangular, pouch-type, or coin-type, using a can.

[0114] The lithium secondary battery according to the present invention can be used as a battery cell for powering small devices, and can also be preferably used as a unit battery in medium- and large-sized battery modules containing a large number of battery cells.

[0115] This provides a battery module including the lithium secondary battery as a unit cell and a battery pack including the same.

[0116] The aforementioned battery module or battery pack can be used as a power source for one or more medium-to-large devices, including power tools; electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems.

[0117] Hereinafter, embodiments of the present invention will be described in detail so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in a variety of different forms and is not limited to the embodiments described herein.

[0118] Examples and Comparative Examples Example 1 A composite transition metal hydroxide (composition: Ni) formed by the aggregation of tens to hundreds of primary particles into secondary particle form. 0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50 A mixture was prepared by mixing (6.2 μm) and LiOH such that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in the LiOH ((Ni+Co+Mn):Li) was 1:0.98. Al(OH)3 (manufactured by Daishu-KC Corporation) was added at a concentration of 1400 ppm relative to the total weight of the composite transition metal hydroxide, Y2O3 (manufactured by Neo Performance Corporation) at a concentration of 1000 ppm relative to the total weight of the composite transition metal hydroxide, and ZrO2 (manufactured by R&F Corporation) at a concentration of 1500 ppm relative to the total weight of the composite transition metal hydroxide.

[0119] The mixture is subjected to primary calcination at 830°C for 6 hours to obtain a primary calcined product, and the primary calcined product is subjected to an average particle size (D) at room temperature. 50 The particles were ground to a size of 3.8 μm.

[0120] The pulverized primary calcined product and LiOH are mixed so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH ((Ni+Co+Mn):Li) is 1:0.04, and the mixture is calcined at 760°C for 9 hours to obtain a secondary calcined product, and the secondary calcined product is pulverized at room temperature to obtain an average particle size (D 50 ) Lithium composite transition metal oxide (composition: LiNi) in single-particle form with a diameter of 3.8 μm 0.87836 Co 0.03493 Mn 0.07985 Al 0.00499 Y 0.00027 Zr 0.0016 O2 was obtained.

[0121] After uniformly mixing the single-particle lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou-KC), a positive electrode active material (composition: LiNi) is formed on the single-particle lithium composite transition metal oxide by heat treatment in an oxygen atmosphere at a temperature of 700°C for 5 hours. 0.85761 Co 0.05489 Mn 0.07978 Al 0.00586 Y 0.00027 Zr 0.00159 O2) was produced. Here, the Co(OH)2 was mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the single-particle lithium composite transition metal oxide (A) was 0.02, and the Al(OH)3 was mixed in an amount of 0.05 parts by weight per 100 parts by weight of the single-particle lithium composite transition metal oxide.

[0122] Example 2 A composite transition metal hydroxide (composition: Ni) formed by the aggregation of tens to hundreds of primary particles into secondary particle form. 0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50): 6.2 μm) and LiOH were mixed so that the ratio ((Ni + Co + Mn): Li) of the total number of moles of transition metals (Ni + Co + Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH became 1:0.98. To this, Al(OH)3 (manufactured by Dazhou · KC) was added at 1400 ppm based on the total weight of the composite transition metal hydroxide, Y2O3 (manufactured by Neo performance) was added at 2000 ppm based on the total weight of the composite transition metal hydroxide, and ZrO2 (manufactured by R&F) was added at 1500 ppm based on the total weight of the composite transition metal hydroxide, and they were mixed to produce a mixture.

[0123] The mixture was primary fired at 830 °C for 6 hours to obtain a primary fired product, and at room temperature, the primary fired product was ground so that the average particle size (D 50 ) became 5.8 μm.

[0124] The ground primary fired product and LiOH were mixed so that the ratio ((Ni + Co + Mn): Li) of the total number of moles of transition metals (Ni + Co + Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH became 1:0.04, and secondary fired at 760 °C for 9 hours to obtain a secondary fired product. At room temperature, the secondary fired product was ground to obtain a lithium composite transition metal oxide in the form of single particles with an average particle size (D 50 ) of 3.8 μm (composition: LiNi 0.87813 Co 0.03492 Mn 0.07983 Al 0.00499 Y 0.00054 Zr 0.00159 O2).

[0125] After uniformly mixing the lithium composite transition metal oxide in the form of single particles, Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou · KC), heat treatment was performed at 700 °C for 5 hours in an oxygen atmosphere to form a coating portion containing Co and Al on the lithium composite transition metal oxide in the form of single particles. The cathode active material (composition: LiNi 0.85738 Co 0.05487 Mn 0.07976 Al 0.00586 Y 0.00054 Zr 0.00159O2) was produced. Here, the Co(OH)2 is mixed in an amount such that the ratio (B / A) of the number of moles of cobalt (B) contained in the cobalt-containing coating material to the total number of moles of metals other than lithium (A) contained in the single-particle form of the lithium composite transition metal oxide is 0.02, and the Al(OH)3 is mixed in an amount of 0.05 parts by weight with respect to 100 parts by weight of the single-particle form of the lithium composite transition metal oxide.

[0126] Example 3 A composite transition metal hydroxide in the form of secondary particles formed by aggregation of dozens to hundreds of primary particles (composition: Ni 0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50 ): 6.2 μm) and LiOH were mixed so that the ratio ((Ni + Co + Mn): Li) of the total number of moles of transition metals (Ni + Co + Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH was 1:0.98. To this, Al(OH)3 (manufactured by Daiwa Kasei Co., Ltd.) was added at 2800 ppm with respect to the total weight of the composite transition metal hydroxide, Y2O3 (manufactured by Neo Performance Co., Ltd.) was added at 1000 ppm with respect to the total weight of the composite transition metal hydroxide, and ZrO2 (manufactured by R&F Co., Ltd.) was added at 1500 ppm with respect to the total weight of the composite transition metal hydroxide, and they were mixed to produce a mixture.

[0127] The mixture was first fired at 830 °C for 6 hours to obtain a first fired product, and the first fired product was pulverized at room temperature so that the average particle size (D 50 ) became 5.8 μm.

[0128] The pulverized first fired product and LiOH were mixed so that the ratio ((Ni + Co + Mn): Li) of the total number of moles of transition metals (Ni + Co + Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH was 1:0.04, and then second fired at 760 °C for 9 hours to obtain a second fired product, and the second fired product was pulverized at room temperature to obtain a single-particle form of lithium composite transition metal oxide with an average particle size (D 50 ) of 5.8 μm (composition: LiNi 0.87338 Co0.03493 Mn 0.07985 Al 0.00998 Y 0.00027 Zr 0.00159 O2 was obtained.

[0129] After uniformly mixing the single-particle lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou-KC), the mixture is heat-treated in an oxygen atmosphere at 700°C for 5 hours to form a positive electrode active material (composition: LiNi) on which a coating portion containing Co and Al is formed on the single-particle lithium composite transition metal oxide. 0.85262 Co 0.05489 Mn 0.07978 Al 0.01085 Y 0.00027 Zr 0.00159 O2) was produced. Here, the Co(OH)2 was mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the single-particle lithium composite transition metal oxide (A) was 0.02, and the Al(OH)3 was mixed in an amount of 0.05 parts by weight per 100 parts by weight of the single-particle lithium composite transition metal oxide.

[0130] Example 4 A composite transition metal hydroxide (composition: Ni) formed by the aggregation of tens to hundreds of primary particles into secondary particle form. 0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50 A mixture was prepared by mixing (6.2 μm) and LiOH such that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in the LiOH ((Ni+Co+Mn):Li) was 1:0.98. Al(OH)3 (manufactured by Daishu-KC Corporation) was added at a concentration of 1400 ppm relative to the total weight of the composite transition metal hydroxide, Y2O3 (manufactured by Neo Performance Corporation) at a concentration of 1000 ppm relative to the total weight of the composite transition metal hydroxide, and ZrO2 (manufactured by R&F Corporation) at a concentration of 3500 ppm relative to the total weight of the composite transition metal hydroxide.

[0131] The mixture is subjected to primary calcination at 830°C for 6 hours to obtain a primary calcined product, and the primary calcined product is subjected to an average particle size (D) at room temperature. 50 The particles were ground to a size of 5.8 μm.

[0132] The pulverized primary calcined product and LiOH are mixed so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH ((Ni+Co+Mn):Li) is 1:0.04, and the mixture is calcined at 760°C for 9 hours to obtain a secondary calcined product, and the secondary calcined product is pulverized at room temperature to obtain an average particle size (D 50 ) Lithium composite transition metal oxide (composition: LiNi) in single-particle form with a diameter of 5.8 μm 0.87651 Co 0.03486 Mn 0.07968 Al 0.00498 Y 0.00027 Zr 0.0037 O2 was obtained.

[0133] After uniformly mixing the single-particle lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou-KC), the mixture is heat-treated in an oxygen atmosphere at 700°C for 5 hours to form a positive electrode active material (composition: LiNi) on which a coating portion containing Co and Al is formed on the single-particle lithium composite transition metal oxide. 0.85576 Co 0.05481 Mn 0.07961 Al 0.00585 Y 0.00027 Zr 0.0037 O2) was produced. Here, the Co(OH)2 was mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the single-particle lithium composite transition metal oxide (A) was 0.02, and the Al(OH)3 was mixed in an amount of 0.05 parts by weight per 100 parts by weight of the single-particle lithium composite transition metal oxide.

[0134] Example 5 A composite transition metal hydroxide (composition: Ni) formed by the aggregation of tens to hundreds of primary particles into secondary particle form.0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50 A mixture was prepared by mixing (6.8 μm) and LiOH such that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in the LiOH ((Ni+Co+Mn):Li) was 1:0.98. Al(OH)3 (manufactured by Daishu-KC Corporation) was added at a concentration of 1400 ppm relative to the total weight of the composite transition metal hydroxide, Y2O3 (manufactured by Neo Performance Corporation) at a concentration of 1000 ppm relative to the total weight of the composite transition metal hydroxide, and ZrO2 (manufactured by R&F Corporation) at a concentration of 1500 ppm relative to the total weight of the composite transition metal hydroxide.

[0135] The mixture is subjected to primary calcination at 830°C for 6 hours to obtain a primary calcined product, and the primary calcined product is subjected to an average particle size (D) at room temperature. 50 The particles were ground to a size of 6.8 μm.

[0136] The crushed primary calcined product and LiOH are mixed so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH ((Ni+Co+Mn):Li) is 1:0.04, and the mixture is calcined at 760°C for 9 hours to obtain a secondary calcined product, and the secondary calcined product is crushed at room temperature to obtain an average particle size (D 50 ) Lithium composite transition metal oxide (composition: LiNi) in single-particle form with a diameter of 6.8 μm 0.87836 Co 0.03493 Mn 0.07985 Al 0.00499 Y 0.00027 Zr 0.0016 O2 was obtained.

[0137] After uniformly mixing the single-particle lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou-KC), a positive electrode active material (composition: LiNi) is formed on the single-particle lithium composite transition metal oxide by heat treatment in an oxygen atmosphere at a temperature of 700°C for 5 hours. 0.85761 Co 0.05489 Mn0.07978 Al 0.00586 Y 0.00027 Zr 0.00159 O2) was produced. Here, the Co(OH)2 was mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the single-particle lithium composite transition metal oxide (A) was 0.02, and the Al(OH)3 was mixed in an amount of 0.05 parts by weight per 100 parts by weight of the single-particle lithium composite transition metal oxide.

[0138] Comparative Example 1 A composite transition metal hydroxide (composition: Ni) formed by the aggregation of tens to hundreds of primary particles into secondary particle form. 0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50 A mixture was prepared by mixing (6.2 μm) and LiOH such that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in the LiOH ((Ni+Co+Mn):Li) was 1:0.98. Al(OH)3 (manufactured by Daishu-KC Co., Ltd.) was added at a concentration of 1400 ppm relative to the total weight of the composite transition metal hydroxide, and ZrO2 (manufactured by R&F Co., Ltd.) was added at a concentration of 1500 ppm relative to the total weight of the composite transition metal hydroxide, and the mixture was then mixed.

[0139] The mixture is subjected to primary calcination at 830°C for 6 hours to obtain a primary calcined product, and the primary calcined product is subjected to an average particle size (D) at room temperature. 50 The particles were ground to a size of 5.8 μm.

[0140] The pulverized primary calcined product and LiOH are mixed so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH ((Ni+Co+Mn):Li) is 1:0.04, and the mixture is calcined at 760°C for 9 hours to obtain a secondary calcined product, and the secondary calcined product is pulverized at room temperature to obtain an average particle size (D 50 ) Lithium composite transition metal oxide (composition: LiNi) in single-particle form with a diameter of 5.8 μm 0.8786 Co0.03494 Mn 0.07987 Al 0.00499 Zr 0.0016 O2 was obtained.

[0141] After uniformly mixing the single-particle lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou-KC), the mixture is heat-treated in an oxygen atmosphere at 700°C for 5 hours to form a positive electrode active material (composition: LiNi) on which a coating portion containing Co and Al is formed on the single-particle lithium composite transition metal oxide. 0.85784 Co 0.0549 Mn 0.0798 Al 0.00586 Zr 0.0016 O2) was produced. Here, the Co(OH)2 was mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the single-particle lithium composite transition metal oxide (A) was 0.02, and the Al(OH)3 was mixed in an amount of 0.05 parts by weight per 100 parts by weight of the single-particle lithium composite transition metal oxide.

[0142] Comparative Example 2 A composite transition metal hydroxide (composition: Ni) formed by the aggregation of tens to hundreds of primary particles into secondary particle form. 0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50 A mixture was prepared by mixing (6.2 μm) and LiOH such that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in the LiOH ((Ni+Co+Mn):Li) was 1:0.98. Y2O3 (manufactured by Neo Performance) was added at a concentration of 1000 ppm relative to the total weight of the composite transition metal hydroxide, and ZrO2 (manufactured by R&F) was added at a concentration of 1500 ppm relative to the total weight of the composite transition metal hydroxide, and the mixture was then mixed.

[0143] The mixture is subjected to primary calcination at 830°C for 6 hours to obtain a primary calcined product, and the primary calcined product is subjected to an average particle size (D) at room temperature. 50The particles were ground to a size of 5.8 μm.

[0144] The pulverized primary calcined product and LiOH are mixed so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH ((Ni+Co+Mn):Li) is 1:0.04, and the mixture is calcined at 760°C for 9 hours to obtain a secondary calcined product, and the secondary calcined product is pulverized at room temperature to obtain an average particle size (D 50 ) Lithium composite transition metal oxide (composition: LiNi) in single-particle form with a diameter of 5.8 μm 0.88336 Co 0.03493 Mn 0.07985 Y 0.00027 Zr 0.00159 O2 was obtained.

[0145] After uniformly mixing the single-particle lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou-KC), the mixture is heat-treated in an oxygen atmosphere at 700°C for 5 hours to form a positive electrode active material (composition: LiNi) on which a coating portion containing Co and Al is formed on the single-particle lithium composite transition metal oxide. 0.86259 Co 0.05489 Mn 0.07978 Al 0.00088 Y 0.00027 Zr 0.00159 O2) was produced. Here, the Co(OH)2 was mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the single-particle lithium composite transition metal oxide (A) was 0.02, and the Al(OH)3 was mixed in an amount of 0.05 parts by weight per 100 parts by weight of the single-particle lithium composite transition metal oxide.

[0146] Comparative Example 3 A composite transition metal hydroxide (composition: Ni) formed by the aggregation of tens to hundreds of primary particles into secondary particle form. 0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50A mixture was prepared by mixing (6.2 μm) and LiOH such that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in the LiOH ((Ni+Co+Mn):Li) was 1:0.98. Al(OH)3 (manufactured by Daishu-KC Co., Ltd.) was added at a concentration of 1400 ppm relative to the total weight of the composite transition metal hydroxide, and Y2O3 (manufactured by Neo Performance Co., Ltd.) was added at a concentration of 1000 ppm relative to the total weight of the composite transition metal hydroxide, and the mixture was then mixed.

[0147] The mixture is subjected to primary calcination at 830°C for 6 hours to obtain a primary calcined product, and the primary calcined product is subjected to an average particle size (D) at room temperature. 50 The particles were ground to a size of 5.8 μm.

[0148] The pulverized primary calcined product and LiOH are mixed so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH ((Ni+Co+Mn):Li) is 1:0.04, and the mixture is calcined at 760°C for 9 hours to obtain a secondary calcined product, and the secondary calcined product is pulverized at room temperature to obtain an average particle size (D 50 ) Lithium composite transition metal oxide (composition: LiNi) in single-particle form with a diameter of 5.8 μm 0.87976 Co 0.03499 Mn 0.07998 Al 0.005 Y 0.00027 O2 was obtained.

[0149] After uniformly mixing the single-particle lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou-KC), the mixture is heat-treated in an oxygen atmosphere at 700°C for 5 hours to form a positive electrode active material (composition: LiNi) on which a coating portion containing Co and Al is formed on the single-particle lithium composite transition metal oxide. 0.85901 Co 0.05494 Mn 0.07991 Al 0.00587 Y 0.00027Co(OH)2 was produced. Here, the Co(OH)2 was mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the single-particle lithium composite transition metal oxide (A) was 0.02, and the Al(OH)3 was mixed in an amount of 0.05 parts by weight per 100 parts by weight of the single-particle lithium composite transition metal oxide.

[0150] Comparative Example 4 A composite transition metal hydroxide (composition: Ni) formed by the aggregation of tens to hundreds of primary particles into secondary particle form. 0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50 A mixture was prepared by mixing (4.19 μm) and LiOH such that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in the LiOH ((Ni+Co+Mn):Li) was 1:0.98. Al(OH)3 (manufactured by Daishu-KC Corporation) was added at a concentration of 1400 ppm relative to the total weight of the composite transition metal hydroxide, Y2O3 (manufactured by Neo Performance Corporation) at a concentration of 1000 ppm relative to the total weight of the composite transition metal hydroxide, and ZrO2 (manufactured by R&F Corporation) at a concentration of 1500 ppm relative to the total weight of the composite transition metal hydroxide.

[0151] The mixture is subjected to primary calcination at 830°C for 6 hours to obtain a primary calcined product, and the primary calcined product is subjected to an average particle size (D) at room temperature. 50 The particles were ground to a size of 3.8 μm.

[0152] The pulverized primary calcined product and LiOH are mixed so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH ((Ni+Co+Mn):Li) is 1:0.04, and the mixture is calcined at 760°C for 9 hours to obtain a secondary calcined product, and the secondary calcined product is pulverized at room temperature to obtain an average particle size (D 50 ) Lithium composite transition metal oxide (composition: LiNi) in single-particle form with a diameter of 3.8 μm 0.87836 Co0.03493 Mn 0.07985 Al 0.00499 Y 0.00027 Zr 0.0016 O2 was obtained.

[0153] After uniformly mixing the single-particle lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou-KC), a positive electrode active material (composition: LiNi) is formed on the single-particle lithium composite transition metal oxide by heat treatment in an oxygen atmosphere at a temperature of 700°C for 5 hours. 0.85761 Co 0.05489 Mn 0.07978 Al 0.00586 Y 0.00027 Zr 0.00159 O2) was produced. Here, the Co(OH)2 was mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the single-particle lithium composite transition metal oxide (A) was 0.02, and the Al(OH)3 was mixed in an amount of 0.05 parts by weight per 100 parts by weight of the single-particle lithium composite transition metal oxide.

[0154] Comparative Example 5 A composite transition metal hydroxide (composition: Ni) formed by the aggregation of tens to hundreds of primary particles into secondary particle form. 0.885 Co 0.035 Mn 0.08 O2, average particle size (D 50 A mixture was prepared by mixing (9 μm) and LiOH such that the ratio of the total number of moles of transition metals (Ni+Co+Mn):Li in the composite transition metal hydroxide to the number of moles of lithium (Li) in the LiOH was 1:0.98. Al(OH)3 (manufactured by Daishu-KC Corporation) was added at a concentration of 1400 ppm relative to the total weight of the composite transition metal hydroxide, Y2O3 (manufactured by Neo Performance Corporation) at a concentration of 1000 ppm relative to the total weight of the composite transition metal hydroxide, and ZrO2 (manufactured by R&F Corporation) at a concentration of 1500 ppm relative to the total weight of the composite transition metal hydroxide.

[0155] The mixture is subjected to primary calcination at 830°C for 6 hours to obtain a primary calcined product, and the primary calcined product is subjected to an average particle size (D) at room temperature. 50 The material was ground to a size of 11 μm.

[0156] The pulverized primary calcined product and LiOH are mixed so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the composite transition metal hydroxide to the number of moles of lithium (Li) contained in LiOH ((Ni+Co+Mn):Li) is 1:0.04, and the mixture is calcined at 760°C for 9 hours to obtain a secondary calcined product, and the secondary calcined product is pulverized at room temperature to obtain an average particle size (D 50 ) Lithium composite transition metal oxide (composition: LiNi) in single-particle form with a diameter of 11 μm 0.87836 Co 0.03493 Mn 0.07985 Al 0.00499 Y 0.00027 Zr 0.0016 O2 was obtained.

[0157] After uniformly mixing the single-particle lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou-KC), a positive electrode active material (composition: LiNi) is formed on the single-particle lithium composite transition metal oxide by heat treatment in an oxygen atmosphere at a temperature of 700°C for 5 hours. 0.85761 Co 0.05489 Mn 0.07978 Al 0.00586 Y 0.00027 Zr 0.00159 O2) was produced. Here, the Co(OH)2 was mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the single-particle lithium composite transition metal oxide (A) was 0.02, and the Al(OH)3 was mixed in an amount of 0.05 parts by weight per 100 parts by weight of the single-particle lithium composite transition metal oxide.

[0158] Experimental example Experimental Example 1: Analysis of Cathode Active Material To confirm the presence of the dopants Al, Y, and Zr in the positive electrode active material produced in Example 1, and how the coating portion containing Co and Al was formed, analysis was performed using a TEM (Transmission Electron Microscope) (Titan Buved G2 600-300) EDX-Mapping, and the TEM EDX-Mapping data is shown in Figure 1.

[0159] Referring to Figure 1, in the case of the positive electrode active material produced in Example 1, it can be confirmed that the dopants Al, Y, and Zr do not have a concentration gradient within the particles but are uniformly distributed, and that the coating portion containing Co and Al is formed as a thin film on the surface of the particles.

[0160] Experimental Example 2: Confirmation of residual lithium content in secondary calcined products The amount of residual lithium present in each of the secondary calcined products produced in Examples 1-5 and Comparative Examples 1-5, i.e., the content of Li2CO3 and LiOH, was confirmed by the following method.

[0161] Specifically, 5 g of each secondary calcined product prepared in Examples 1-5 and Comparative Examples 1-5 was added to 100 g of distilled water and mixed for 5 minutes, after which filtering was performed. After filtering, the amounts of Li2CO3 and LiOH dissolved in the distilled water were measured using a pH meter by titration (using 0.1 N HCl), and these results are shown in Table 1.

[0162] [Table 1]

[0163] Experimental Example 3: Evaluation of Volume Retention Rate The positive electrode active materials, carbon black conductive material, and polyvinylidene fluoride (PVDF) binder prepared in Examples 1-5 and Comparative Examples 1-5 were mixed in N-methylpyrrolidone (NMP) solvent in a ratio of 96:2:2 to produce a positive electrode slurry. The positive electrode slurry was applied to one surface of an aluminum current collector, dried at 150°C, and rolled to produce a positive electrode.

[0164] A lithium metal electrode was used as the negative electrode, and an electrode assembly was manufactured by interposing a porous polyethylene separator between the positive and negative electrodes. After positioning the electrode assembly inside a battery case, an electrolyte solution was injected into the case to manufacture a half-cell. The electrolyte solution was prepared by dissolving 1.0 M LiPF6 in an organic solvent mixture of ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) in a volume ratio of 3:4:3.

[0165] For each half-cell manufactured in this manner, the lithium secondary battery capacity was measured by repeatedly performing 50 charge-discharge cycles at a constant current of 0.33C in the range of 3.0 to 4.25V at 45°C. The capacity retention rate was defined as the percentage of the discharge capacity after 50 cycles relative to the discharge capacity after 1 cycle, and this is shown in Table 2 below.

[0166] [Table 2]

[0167] Experimental Example 4: Evaluation of Thermal Stability For each half-cell manufactured as in Experimental Example 3, Example 1 and Comparative Example 4 were charged in CC / CV mode to 4.25V with a constant current of 0.2C at 25°C (end current: 0.05C). Then, the batteries were disassembled while charged, the positive electrode was cleaned with DMC, and the heat flow was measured using a differential scanning calorimeter (DSC) while increasing the temperature at 10°C / min. The results, total heat generation, onset (peak start) temperature, main peak temperature, and instantaneous maximum heat generation are shown in Table 3 below.

[0168] [Table 3]

[0169] Referring to Table 1, it can be confirmed that in the case of the positive electrode active materials of Examples 1 to 5, the amount of residual lithium, i.e., the total content of Li2CO3 and LiOH, decreases.

[0170] Referring to Tables 2 and 3, it can be confirmed that batteries containing the positive electrode active materials of Examples 1 to 5 have excellent lifespan characteristics due to their high capacity retention rate, and that batteries containing the positive electrode active material of Example 1 have excellent thermal stability.

[0171] In contrast, the positive electrode active material of Comparative Example 1 does not contain Y and has problems with grain growth, so it can be confirmed that the capacity retention rate of batteries containing it decreases. Similarly, the positive electrode active material of Comparative Example 2 does not contain Al and has a form with many defects and increased cation mixing, so it can be confirmed that the capacity retention rate of batteries containing it decreases. Furthermore, the positive electrode active material of Comparative Example 3 does not contain Zr, which maintains structural stability, so it can be confirmed that the capacity retention rate decreases. Furthermore, the positive electrode active material of Comparative Example 4 has a small average particle size, resulting in a low battery capacity retention rate and poor thermal stability. Furthermore, the positive electrode active material of Comparative Example 5 has a large average particle size, resulting in a long lithium migration distance in the particles, so it can be confirmed that the battery capacity retention rate decreases. In addition, although not shown in Table 2, it was confirmed that the resistance characteristics of the positive electrode active material of Comparative Example 5 are not good (high initial resistance and resistance increase rate).

Claims

1. Average particle size (D ５０ ) contains a lithium composite transition metal oxide in single-particle form, where the particle size is greater than 5.5 μm and less than or equal to 10.0 μm. The lithium composite transition metal oxide is a positive electrode active material containing Al, Y, and Zr.

2. The positive electrode active material according to claim 1, wherein the Al is contained in an amount of 500 ppm to 3,000 ppm relative to the total weight of the lithium composite transition metal oxide.

3. The positive electrode active material according to claim 1, wherein Y is contained in an amount of 100 ppm to 2,000 ppm relative to the total weight of the lithium composite transition metal oxide.

4. The positive electrode active material according to claim 1, wherein the Zr is contained in an amount of 500 ppm to 5,000 ppm relative to the total weight of the lithium composite transition metal oxide.

5. The positive electrode active material according to claim 1, wherein the lithium composite transition metal oxide contains 60 mol% or more of nickel relative to the total number of moles of metals other than lithium.

6. The positive electrode active material according to claim 1, wherein the lithium composite transition metal oxide has a composition represented by the following chemical formula 1. [Chemical formula 1] Li ｘ [Ni ａ Co ｂ Mn ｃ Al ｄ Y ｅ Zr ｆ M1 ｇ ]O ２－ｙ A ｙ In the aforementioned chemical formula 1, M1 is one or more selected from B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca. A is one or more elements selected from F, Cl, Br, I, and S. 0.9 ≤ x ≤ 1.2, 0.6 ≤ a < 1, 0 ≤ b ≤ 0.4, 0 ≤ c ≤ 0.4, 0 < d ≤ 0.01, 0 < e ≤ 0.0006, 0 < f ≤ 0.005, 0 ≤ g ≤ 0.2, a + b + c + d + e + f + g = 1, 0 ≤ y ≤ 0.

2.

7. The positive electrode active material according to claim 1, further comprising a coating portion containing Co formed on the lithium composite transition metal oxide in single-particle form.

8. The positive electrode active material according to claim 7, wherein the coating portion further comprises Al, Zr, or a combination thereof.

9. (A) A step of mixing a cathode active material precursor which is a composite transition metal hydroxide, a composite transition metal oxyhydroxide or a combination thereof, a lithium-containing raw material, an aluminum-containing raw material, a yttrium-containing raw material and a zirconium-containing raw material to produce a mixture, (B) A step of producing a primary calcined product by primary calcining the mixture at a temperature of 820°C to 950°C, (C) A method for producing a positive electrode active material according to claim 1, comprising the step of selectively mixing a second lithium-containing raw material with the primary calcined product and then performing a secondary calcination at a temperature of 700°C to 850°C to produce a secondary calcined product.

10. The method for producing a positive electrode active material according to claim 9, further comprising the step of (B') grinding the primary calcined product before step (C).

11. (C') A method for producing a positive electrode active material according to claim 9, further comprising the step of pulverizing the secondary calcined product.

12. (D) A method for producing a positive electrode active material according to claim 9, further comprising the step of mixing the secondary calcined product with a cobalt-containing coating material and then heat-treating it.

13. The method for producing a positive electrode active material according to claim 12, wherein in step (D), when mixing the secondary calcined product with the cobalt-containing coating material, an aluminum-containing coating material, a zirconium-containing coating material, or a combination thereof is further mixed.

14. The method for producing a positive electrode active material according to claim 12, wherein the cobalt-containing coating material is mixed in an amount such that the ratio (B / A) of the number of moles of cobalt contained in the cobalt-containing coating material to the total number of moles of metals other than lithium contained in the secondary calcined product (A) is 0.01 to 0.

03.

15. The method for producing a positive electrode active material according to claim 13, wherein the aluminum-containing coating material is mixed in an amount of 0.03 to 0.10 parts by weight per 100 parts by weight of the secondary firing product.

16. The method for producing a positive electrode active material according to claim 12, wherein the heat treatment is performed under an oxygen atmosphere.

17. The method for producing a positive electrode active material according to claim 12, wherein the heat treatment is performed at a temperature of 600°C to 800°C.

18. A positive electrode comprising the positive electrode active material according to any one of claims 1 to 8.

19. The positive electrode according to claim 18, The negative electrode and, A separator interposed between the positive electrode and the negative electrode, A lithium secondary battery containing an electrolyte.

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