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

Abstract

The present invention relates to a single-particle form cathode active material with little particle deformation and almost no change in particle size distribution even after rolling, which contains a single-particle form lithium composite transition metal oxide. The lithium composite transition metal oxide contains Ni, Co, Mn, Al, and M1, and M1 is one or more selected from Zr, Y, K, Sr, and Ba. The present invention relates to a cathode active material satisfying the following Formula 1, a method for producing the same, a cathode containing the same, and a lithium secondary battery. [Formula 1] |1 - α / β| ≤ 0.1 In Formula 1 above, α is the value of (D 90 - D 10 ) / D 50 , and β is the value of (D 2 - D 2 ) / D 90 - D 10 ) / D 50 after rolling the cathode active material at 1,000 kgf / cm The value of.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0051887 filed on April 20, 2023, and all the contents disclosed in the document of the Korean Patent Application are incorporated herein by reference.

[0002] The present invention relates to a positive electrode active material, a method for manufacturing the same, a positive electrode and a lithium secondary battery including the same, and more specifically, to a positive electrode active material including a single-particle form of a lithium composite transition metal oxide capable of improving battery performance, a method for manufacturing the same, and a positive electrode and a lithium secondary battery including the same.

Background Art

[0003] Recently, with the development of technologies and the increasing demand for mobile devices and electric vehicles, the demand for secondary batteries as an energy source has been rapidly increasing. Among such secondary batteries, lithium secondary batteries having high energy density, high voltage, long cycle life, and low self-discharge rate have been commercialized and widely used.

[0004] Lithium transition metal oxides such as lithium cobalt oxide such as LiCoO2, lithium nickel oxide such as LiNiO2, lithium manganese oxide such as LiMnO2 or LiMn2O4, and lithium iron phosphate oxide such as LiFePO4 have been developed as positive electrode active materials of lithium secondary batteries. Recently, lithium composite transition metal oxides containing two or more transition metals, such as Li[Ni Co b Mn c O2, Li[Ni a Co b Al c O2, Li[Ni a Co b Mn c Al d O2, have been developed and widely used.

[0005] Lithium composite transition metal oxides containing two or more transition metals developed to date are typically manufactured in the form of spherical secondary particles, where tens to hundreds of primary particles aggregate. However, recently, in order to solve the structural and thermal stability problems of secondary particle-form cathode active materials, the development of single-particle-form cathode active materials has been accelerating. Specifically, when secondary particle-form cathode active materials are applied to lithium secondary batteries, they generate a large amount of gas, causing the battery volume to expand. Furthermore, if the nickel content in the cathode material is increased to achieve high capacity, the risk of fire also increases. Therefore, there is a growing need for the development of single-particle-form cathode active materials with superior stability.

[0006] Therefore, there is a need to develop single-particle positive electrode active materials that offer excellent stability and can improve various battery performance characteristics 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 capacity, initial efficiency, lifespan, and resistance of batteries when applied to them.

[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 performance. [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 provides a positive electrode active material comprising a lithium composite transition metal oxide in single-particle form, wherein the lithium composite transition metal oxide comprises Ni, Co, Mn, Al and M1, and M1 is one or more selected from Zr, Y, K, Sr and Ba, satisfying the following formula 1. [Formula 1] |1-α / β|≦0.1 In the above formula 1, α is (D 90 -D 10 ) / D 50 This is the value, and β is the positive electrode active material at 1,000 kgf / cm². 2 ~7,000 kgf / cm² 2 (D 90 -D 10 ) / D 50 This is the value.

[0012] (2) In the present invention, the lithium composite transition metal oxide provides a positive electrode active material having a layered structure.

[0013] (3) In the present invention, in (1) or (2) above, the lithium composite transition metal oxide is the average particle size (D 50 The present invention provides a positive electrode active material having a diameter of 3.00 μm to 8.00 μm.

[0014] (4) The present invention provides a positive electrode active material in any one of (1) to (3) above, wherein the lithium composite transition metal oxide is doped with Al and M1.

[0015] (5) The present invention provides a positive electrode active material in which, in any one of (1) to (4) above, 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.

[0016] (6) The present invention provides a positive electrode active material in which, in any one of (1) to (5) above, M1 is contained in an amount of 100 ppm to 5,000 ppm relative to the total weight of the lithium composite transition metal oxide.

[0017] (7) The present invention provides a positive electrode active material in which, in any one of (1) to (6) above, the lithium composite transition metal oxide contains 60 mol% or more nickel relative to the total number of moles of metals other than lithium.

[0018] (8) In any one of (1) to (7) above, the present invention provides a positive electrode 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 M1 e M2 f ]O 2-y A y In the above chemical formula 1, M1 is one or more elements selected from Zr, Y, K, Sr, and Ba. M2 is one or more elements selected from B, Ba, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo, W, and P. A is one or more elements selected from F, Cl, Br, I, and S. 1.0 ≤ x ≤ 1.3, 0.6 ≤ a < 1, 0.0 <b≦0.4、0.0<c≦0.4、0.0<d≦0.01、0.0<e≦0.005、0.0≦f≦0.2、a+b+c+d+e+f=1、0≦y≦0.2である。

[0019] (9) The present invention provides a step of producing a mixture by mixing (A) a positive electrode active material precursor containing Ni, Co and Mn, an aluminum-containing raw material, an M1-containing raw material and a first lithium-containing raw material, (B) A step of producing a primary calcined product by primary calcining the mixture at a temperature of 800°C to 950°C, (C) The process includes the step of mixing a second lithium-containing raw material with the primary calcined product and then performing a secondary calcination at a temperature of 680°C to 850°C to produce a secondary calcined product. The aforementioned M1 is one or more selected from Zr, Y, K, Sr, and Ba. The present invention provides a method for producing a positive electrode active material, wherein the M1-containing raw material is mixed in an amount of 100 ppm to 5,000 ppm relative to the total weight of the positive electrode active material precursor.

[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 positive electrode comprising a positive electrode active material according to any one of (1) to (8) above.

[0023] (13) The present invention provides a lithium secondary battery comprising a positive electrode according to (12), a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. [Effects of the Invention]

[0024] The positive electrode active material of the present invention comprises a lithium composite transition metal oxide in single-particle form, wherein the lithium composite transition metal oxide comprises Ni, Co, Mn, Al, and M1, and M1 is one or more selected from Zr, Y, K, Sr, and Ba, satisfying formula 1 described herein, resulting in minimal particle deformation and almost no change in particle size distribution after rolling. This makes it possible to improve the capacity, initial efficiency, lifespan, and resistance of lithium secondary batteries.

[0025] 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. [Modes for carrying out the invention]

[0026] The present invention will be described in more detail below to facilitate understanding of it.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] "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.

[0032] 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.

[0033] positive electrode active material The present invention provides a positive electrode active material comprising a lithium composite transition metal oxide in single-particle form, wherein the lithium composite transition metal oxide comprises Ni, Co, Mn, Al, and M1, and M1 is one or more selected from Zr, Y, K, Sr, and Ba, satisfying the following formula 1. The lithium composite transition metal oxide may have a layered structure.

[0034] [Formula 1] |1-α / β|≦0.1

[0035] In the above formula 1, α is (D 90 -D 10 ) / D 50 This is the value, and β is the positive electrode active material at 1,000 kgf / cm². 2 ~7,000 kgf / cm² 2 (D 90 -D 10 ) / D 50 This is the value.

[0036] The inventors have found that when the positive electrode active material contains a lithium composite transition metal oxide in single-particle form, and the lithium composite transition metal oxide contains Ni, Co, Mn, Al, and M1, and satisfies the above formula 1, the deformation of the particles of the positive electrode active material is reduced, and various performance aspects of the lithium secondary battery can be improved, thus completing the present invention. Specifically, the inventors have found that when the lithium composite transition metal oxide contains Al as an essential component, Al substitutes for the positions of some transition metal ions in the crystal structure, resulting in higher structural stability and improved performance of the lithium secondary battery. When M1 is also included, a positive electrode active material with excellent particle strength and a large grain size can be provided. On the other hand, when the positive electrode active material does not contain Al, the thermal and structural stability of the positive electrode active material is low, which leads to problems in battery performance due to deformation of the oxide lattice during charge and discharge cycles. When M1 is not included, there is a problem of not satisfying the above formula 1, i.e., a problem of low particle strength and / or a small grain size.

[0037] According to the present invention, one or more M1 selected from Zr, Y, K, Sr, and Ba are elements that can improve the crystallinity and single-particle degree of the positive electrode active material, and more specifically, two or more selected from Zr, Y, K, Sr, and Ba, and more specifically, Zr and Y.

[0038] According to the present invention, the value in formula 1 may be 0.1 or less, specifically 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, or 0.05 or less. This means that the particle strength of the positive electrode active material is excellent and deformation is minimal even when pressure is applied to the positive electrode active material. When the value in formula 1 is within the above range, the capacity, initial efficiency, lifespan, and resistance performance of the battery containing the positive electrode active material can be excellent. On the other hand, when the value in formula 1 is greater than 0.1, the particle strength is low, which increases particle breakage at the electrodes, resulting in problems with lifespan and resistance performance.

[0039] According to the present invention, the lithium composite transition metal oxide has an average particle size (D 50The average particle size (D) of the lithium composite transition metal oxide may be 3.00 μm to 8.00 μm. 50 Specifically, the average particle size (D) of the lithium composite transition metal oxide may be 3.00 μm or more, 3.50 μm or more, 7.00 μm or less, 7.50 μm or less, or 8.00 μm or less. 50 If the above range is present, the electrochemical performance can be optimized.

[0040] According to the present invention, the lithium composite transition metal oxide may be doped with Al and M1. In this case, i.e., when the lithium composite transition metal oxide contains Al and M1 as dopants, the structural stability of the positive electrode active material is further increased, cation mixing is reduced, the grain size is larger, and the capacity, initial efficiency, lifespan, and resistance performance of the lithium secondary battery can be further improved.

[0041] To further improve the structural stability of the single-particle positive electrode active material with a small average particle size and to increase the grain size, the lithium composite transition metal oxide may, more specifically, be doped with Al, Zr, and Y.

[0042] According to the present invention, the Al may be present 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 and resistance performance of the battery can be improved.

[0043] According to the present invention, M1 may be present in an amount of 100 ppm to 5,000 ppm relative to the total weight of the lithium composite transition metal oxide.

[0044] On the other hand, when M1 is Y and Zr, Y may be present in an amount of 100 ppm to 2,000 ppm relative to the total weight of the lithium composite transition metal oxide, and Zr may be present in an amount of 500 ppm to 5,000 ppm relative to the total weight of the lithium composite transition metal oxide. When the content of Y is within the above range, the grain size contained in each particle is large, which can improve the capacity and life performance of the battery. When the content of Zr is within the above range, Zr is stably doped into the lithium layer, improving structural stability during lithium insertion and removal, resulting in superior particle strength, which can improve the life and resistance performance of the battery.

[0045] 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.

[0046] 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.

[0047] [Chemical formula 1] Li x [Ni a Co b Mn c Al d M1 e M2 f ]O 2-y A y

[0048] In the above chemical formula 1, M1 is one or more elements selected from Zr, Y, K, Sr, and Ba. M2 is one or more elements selected from B, Ba, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo, W, and P. A is one or more elements selected from F, Cl, Br, I, and S. 1.0 ≤ x ≤ 1.3, 0.6 ≤ a < 1, 0.0 <b≦0.4、0.0<c≦0.4、0.0<d≦0.01、0.0<e≦0.005、0.0≦f≦0.2、a+b+c+d+e+f=1、0≦y≦0.2である。

[0049] The above 'a' refers to the atomic fraction of nickel among the metal elements in the lithium composite transition metal oxide, and may be 0.6 or more, 0.8 or more, 0.85 or more, 0.95 or less, 0.98 or less, or 1.0 or less.

[0050] The term b refers to the atomic fraction of cobalt among the metal elements in the lithium composite transition metal oxide, and may be 0.0 or more, 0.01 or more, 0.15 or less, 0.2 or less, or 0.4 or less.

[0051] The aforementioned c represents the atomic fraction of manganese among the metal elements in the lithium composite transition metal oxide, and may be 0.0 or more, 0.01 or more, 0.15 or less, 0.2 or less, or 0.4 or less.

[0052] The above d represents the atomic fraction of aluminum among the metal elements in the lithium composite transition metal oxide, and may be greater than 0.0, 0.002 or more, 0.003 or more, 0.006 or less, 0.008 or less, or 0.01 or less.

[0053] The term e refers to the atomic fraction of element M1 among the metal elements in the lithium composite transition metal oxide, and may be greater than 0.0, 0.0001 or more, 0.0002 or more, 0.0006 or more, 0.002 or less, 0.003 or less, or 0.005 or less.

[0054] The value of f represents the atomic fraction of the M2 element among the metal elements in the lithium composite transition metal oxide, and may be 0.0 or greater, 0.05 or less, 0.1 or less, or 0.2 or less.

[0055] 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, battery life and resistance performance can be improved, and gas generation 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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 containing Ni, Co, and Mn, an aluminum-containing raw material, an M1-containing raw material, and a first lithium-containing raw material to produce a mixture; (B) primary firing the mixture at a temperature of 800°C to 950°C to produce a primary fired product; and (C) mixing a second lithium-containing raw material with the primary fired product and then secondary firing at a temperature of 680°C to 850°C to produce a secondary fired product. Here, M1 is one or more selected from Zr, Y, K, Sr, and Ba, and the M1-containing raw material is mixed in an amount of 100 ppm to 5,000 ppm relative to the total weight of the positive electrode active material precursor.

[0060] The inventors of the present invention have found that when lithium is introduced in two separate steps, (A) and (C), and the firing is carried out in two separate steps, and when M1 is introduced as a dopant in a specific amount or more before the primary firing, single-particle lithium transition metal oxide is produced, resulting in less deformation of the positive electrode active material particles and less change in particle size distribution even after rolling, thus completing the present invention.

[0061] The positive electrode active material precursor containing Ni, Co, and Mn may have a composition represented by the following chemical formula 2 or chemical formula 3.

[0062] [Chemical formula 2] Ni a’ Co b’ Mn c’ M2 d’ (OH)2

[0063] [Chemical formula 3] Ni a’ Co b’ Mn c’ M2 d’ O.OH

[0064] In the aforementioned chemical formulas 2 and 3, M2 is one or more elements selected from B, Ba, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo, W, and P. 0.6 ≤ a' < 1, 0.0 <b’≦0.4、0.0<c’≦0.4、0.0≦d’≦0.2である。

[0065] 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 may be added in an amount of 500 ppm to 3,000 ppm relative to the total weight of the positive electrode active material precursor. Specifically, the content of the aluminum-containing raw material may be 500 ppm or more, 600 ppm or more, 700 ppm or more, 800 ppm or more, 900 ppm or more, 1,000 ppm or more, 1,100 ppm or more, 1,200 ppm or more, 1,300 ppm or more, 1,400 ppm or more, 2,800 ppm or less, 2,900 ppm or less, or 3,000 ppm or less relative to the total weight of the positive electrode active material precursor. In this case, the crystal structure inside the positive electrode active material is stabilized, which has the advantage of providing better battery life performance.

[0066] The M1-containing raw material may be, but is not limited to, M1-containing hydroxides, oxides, chlorides, nitrates, sulfur oxides, sulfides, etc.

[0067] On the other hand, if M1 is Y, the yttrium (Y)-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. Specifically, the content of the yttrium-containing raw material may be 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, 500 ppm or more, 600 ppm or more, 700 ppm or more, 800 ppm or more, 900 ppm or more, 1,000 ppm or more, and 2,000 ppm or less relative to the total weight of the positive electrode active material precursor. In this case, the grain size contained in each particle is large, which can further improve the battery's capacity and lifespan performance.

[0068] Furthermore, if M1 is Zr, the 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, 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. Specifically, the content of the zirconium-containing raw material may be 500 ppm or more, 1000 ppm or more, 1500 ppm or more, 3000 ppm or less, 3500 ppm or less, 4000 ppm or less, 4500 ppm or less, or 5000 ppm or less relative to the total weight of the positive electrode active material precursor. In this case, Zr is stably doped into the lithium layer, and there is an advantage that structural stability is further improved during lithium insertion and deinsertion, and particle strength is also further improved.

[0069] When the mixture is subjected to primary calcination at a temperature of 800°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. Specifically, the primary calcination temperature may be 800°C or higher, 810°C or higher, 820°C or higher, 830°C or higher, 840°C or higher, 850°C or higher, 900°C or lower, 910°C or lower, 920°C or lower, 930°C or lower, 940°C or lower, or 950°C or lower. When the primary calcination temperature is within the above range, the primary particles of the positive electrode active material precursor aggregate to form a primary calcined product in the form of a structurally stable single particle. When the primary calcination temperature is below 800°C, there is a problem that the primary particles do not aggregate sufficiently, and when it is above 950°C, there is a problem that a calcined product is produced that is structurally unstable and has a low degree of crystallinity.

[0070] The aforementioned primary calcination may be carried out under an oxygen atmosphere in order to prevent the lithium transition metal oxide from degenerating into a rock salt structure.

[0071] The aforementioned primary firing may be carried out for 3 to 12 hours, specifically for 3 hours or more, 4 hours or more, 5 hours or more, 6 hours or more and 9 hours or less, 10 hours or less, 11 hours or less, or 12 hours or less, in order to aggregate the primary particles and improve the crystallinity of the primary fired product.

[0072] When the primary-fired product is subjected to secondary firing at a temperature of 680°C to 850°C, lithium is inserted into the primary-fired product to produce a secondary-fired product. Here, the secondary-fired product is a lithium composite transition metal oxide in single-particle form. Specifically, the secondary firing temperature may be 680°C or higher, 700°C or higher, 720°C or higher, 740°C or higher, 760°C or higher, 780°C or higher, 800°C or higher, 840°C or lower, or 850°C or lower. When the secondary firing temperature is within the above range, lithium is inserted into the rock salt structure formed on the surface of the primary-fired product by the high temperature during primary firing, restoring it to a layered structure and reducing lithium byproducts. On the other hand, when the secondary firing temperature is below 680°C, there is a problem that the lithium insertion rate is slow due to the low temperature, and when it is above 850°C, there is a problem that the surface of the primary-fired product degenerates to a rock salt structure due to the high temperature, and lithium byproducts remain.

[0073] The aforementioned secondary calcination may be carried out under an oxygen atmosphere in order to prevent the lithium transition metal oxide from degenerating into a rock salt structure.

[0074] The aforementioned secondary firing may be performed for 3 to 12 hours, specifically for 3 hours or more, 4 hours or more, 5 hours or more, 6 hours or more, 9 hours or more but 9 hours or less, 10 hours or less, 11 hours or less, or 12 hours or less, in order to increase the degree of crystallinity of the crystal structure inside the positive electrode active material.

[0075] 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') is performed to prevent the initial resistance from becoming high by grinding the primary calcined product to an average particle size (D 50 The material may be ground to a size of 3.50 μm to 6.00 μm.

[0076] The method for producing a positive electrode active material according to the present invention may further include (C') a step of grinding the secondary calcined product. The (C') step may also include grinding the secondary calcined product to an average particle size (D 50 The material may be ground to a size of 3.50 μm to 6.00 μm.

[0077] 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. In this case, the desired average particle size (D 50 A positive electrode active material having ) can be easily obtained.

[0078] The positive electrode active material according to the present invention is manufactured by a process in which lithium-containing raw material is added in two stages. That is, the lithium-containing raw material is added before the primary calcination and before the secondary calcination. In this case, there is an advantage in that lithium is inserted into the rock salt structure formed on the surface, which facilitates the recovery to a layered structure. On the other hand, if the lithium-containing raw material is added in one stage before the primary calcination, there is a problem of decreased electrochemical performance due to an increase in lithium byproducts, and if the lithium-containing raw material is not added in the secondary calcination step, a problem arises in which a slow reaction rate, high temperature and long time are required.

[0079] When the lithium-containing raw material is added in two separate steps, in step (A), the first lithium-containing raw material can be mixed such 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 1:0.98 or higher, 1:0.99 or higher, 1:1.00 or higher, 1:1.01 or higher, 1:1.02 or higher, 1:1.04 or lower, or 1:1.05 or lower. In step (C), the second lithium-containing raw material can be mixed such 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 or higher, 1:0.05 or lower, 1:0.06 or lower, 1:0.07 or lower, 1:0.08 or lower, 1:0.09 or lower, or 1:1.10 or lower.

[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 may be performed at temperatures of 600°C or higher, 610°C or higher, 620°C or higher, 630°C or higher, 640°C or higher, 650°C or higher and 720°C or lower, 740°C or lower, 760°C or lower, 780°C or lower, and 800°C or lower, in order to ensure that the coating portion is formed with an appropriate thickness. After that, the temperature may be lowered to approximately 450°C to 550°C, and then heat treatment may be performed at temperatures of 450°C or higher, 460°C or higher, 470°C or higher, 480°C or higher and 520°C or lower, 530°C or lower, 540°C or lower, and 550°C or lower. In other words, the heat treatment may be performed at 600°C to 800°C in a single firing profile, followed by heat treatment at 450°C to 550°C.

[0089] According to the present invention, the heat treatment may be performed for a period of 1 hour or more, 2 hours or more, 3 hours or more, 8 hours or less, 9 hours or less, or 10 hours or less 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 rechargeable 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 for purposes such as improving battery life, suppressing the decrease in battery capacity, and improving battery discharge capacity. These additives may include, for example, haloalkylene carbonate compounds such as 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. Here, the additives 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 has excellent performance and is therefore 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 (4.20 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 1:1.03. 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 890°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 3.80 μm.

[0120] The crushed primary fired product and LiOH are mixed such 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 is 1:0.01, and secondary firing is performed at 820 °C for 9 hours to obtain a secondary fired product. The secondary fired product is crushed at room temperature, and the average particle size (D 50 ) is 3.80 μm, and a single particle form lithium composite transition metal oxide (composition: LiNi 0.87836 Co 0.03493 Mn 0.07985 Al 0.00499 Y 0.00027 Zr 0.0016 O2) is obtained.

[0121] After uniformly mixing the single particle form lithium composite transition metal oxide with Co(OH)2 (manufactured by Huayou) and Al(OH)3 (manufactured by Dazhou · KC), heat treatment is performed at a temperature of 700 °C for 5 hours and at a temperature of 500 °C for 3 hours in an oxygen atmosphere to produce a positive electrode active material in which a coating portion containing Co and Al is formed on the single particle form lithium composite transition metal oxide. 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 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 lithium composite transition metal oxide.

[0122] Example 2 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 50A mixture was prepared by mixing (4.20 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 1:1.03. 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 2000 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.

[0123] The mixture is subjected to primary calcination at 890°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 3.80 μm.

[0124] 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 1:0.01, and the mixture is calcined at 820°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 3.80 μm 0.87813 Co 0.03492 Mn 0.07983 Al 0.00499 Y 0.00054 Zr 0.00159 O2 was obtained.

[0125] 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 was heat-treated in an oxygen atmosphere at 700°C for 5 hours and at 500°C for 3 hours to produce a positive electrode active material in which a coating portion containing Co and Al was formed on the single-particle lithium composite transition metal oxide. 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.

[0126] 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 50 A mixture was prepared by mixing (4.20 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 1:1.03. Al(OH)3 (manufactured by Daishu-KC Corporation) was added at a concentration of 2800 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.

[0127] 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 3.80 μm.

[0128] 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 1:0.01, and the mixture is calcined at 820°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 3.80 μm 0.87338 Co 0.03493 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 was heat-treated in an oxygen atmosphere at 700°C for 5 hours and at 500°C for 3 hours to produce a positive electrode active material in which a coating portion containing Co and Al was formed on the single-particle lithium composite transition metal oxide. 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 50A mixture was prepared by mixing (4.20 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 1:1.03. 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 3000 ppm relative to the total weight of the composite transition metal hydroxide.

[0131] The mixture is subjected to primary calcination at 890°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 3.80 μm.

[0132] 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 1:0.01, and the mixture is calcined at 820°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 3.80 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 was heat-treated in an oxygen atmosphere at 700°C for 5 hours and at 500°C for 3 hours to produce a positive electrode active material in which a coating portion containing Co and Al was formed on the single-particle lithium composite transition metal oxide. 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] Comparative Example 1 Lithium composite transition metal oxide (composition: LiNi) in single-particle form was produced in the same manner as in Example 1, except that Y2O3 was not added during the preparation of the mixture. 0.8786 Co 0.03494 Mn 0.07987 Al 0.00499 Zr 0.0016 A positive electrode active material was manufactured in which a coating portion containing Co and Al was formed on O2.

[0135] Comparative Example 2 Lithium composite transition metal oxide (composition: LiNi) is produced in single-particle form using the same method as in Example 1, except that Al(OH)3 is not added during the preparation of the mixture. 0.88336 Co 0.03493 Mn 0.07985 Y 0.00027 Zr 0.00159 A positive electrode active material was manufactured in which a coating portion containing Co and Al was formed on O2.

[0136] Comparative Example 3 Lithium composite transition metal oxide (composition: LiNi) in single-particle form is produced in the same manner as in Example 1, except that ZrO2 is not added during the preparation of the mixture. 0.87976 Co 0.03499 Mn 0.07998 Al 0.005 Y 0.00027A positive electrode active material was manufactured in which a coating portion containing Co and Al was formed on O2.

[0137] Experimental example Experimental Example 1: Particle Size Analysis of Cathode Active Material After taking 0.01 g each of the positive electrode active materials (powder) prepared in Examples 1-4 and Comparative Examples 1-3, place them in vials containing 30 ml of ultrapure water and 500 μl of dispersant. Disperse the positive electrode active materials with a sonicator for 1 minute, then place them in a particle size analyzer (PSA) (Microtrac S3500) to determine the D of each positive electrode active material. 10 , D 50 , D 90 Obtain the value of α=(D 90 -D 10 ) / D 50 The value of D was calculated. 10 , D 50 , D 90 This refers to the particle size at the 10%, 50%, and 90% points of the cumulative volume distribution by particle size.

[0138] Furthermore, 3g each of the positive electrode active materials (powder) produced in Examples 1-4 and Comparative Examples 1-3 was taken and then subjected to a pelletization process of 6,780.6 kgf / cm² using an automatic pellet press (Carver, 3887.4). 2 Pelletization was performed by rolling under pressure (3g of positive electrode active material (powder) was placed in a circular pellet holder with a diameter of 13mm and pressure was applied until a force equivalent to 9,000kgf was reached). The pellets were then crushed into powder again using a mortar and pestle for 1 minute. After taking 0.01g portions of the crushed positive electrode active material, they were placed in vials containing 30ml of ultrapure water and 500μl of dispersant, and the positive electrode active material was dispersed using a sonicator for 1 minute. The particles were then placed in a particle size analyzer (PSA) (Microtrac, S3500) to determine the D content of each positive electrode active material. 10 , D 50 , D 90 Obtain the value of β=(D 90 -D 10 ) / D 50 The value was calculated.

[0139] For reference, crushing using a mortar and pestle does not affect the average particle size of the positive electrode active material.

[0140] The values ​​of α and β mentioned above were substituted into Equation 1 below, and the values ​​calculated using Equation 1 are shown in Table 1 below.

[0141] [Table 1]

[0142] Experiment Example 2: Evaluation of Battery Performance The positive electrode active materials, carbon black conductive material, and polyvinylidene fluoride (PVDF) binder prepared in Examples 1-4 and Comparative Examples 1-3 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.

[0143] 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.

[0144] For each half-cell manufactured in this manner, the initial charge capacity and initial discharge capacity were measured while charging at 0.1C in CC-CV mode at 25°C until the voltage reached 4.3V, and then discharging to 3.0V with a constant current of 0.1C. The initial efficiency and DC internal resistance (DCIR) were calculated and are shown in Table 2 below. For reference, the initial efficiency value is the percentage of the initial discharge capacity relative to the initial charge capacity, and the DCIR value is calculated by dividing the difference between the voltage at 60 seconds of discharge with a constant current of 0.1C and the initial voltage by the applied current.

[0145] Furthermore, the capacity of the lithium secondary battery was measured by repeating the charge-discharge cycle 50 times at a constant current of 0.33C in the range of 3.0 to 4.25V at 45℃. The capacity retention rate was defined as the percentage of the discharge capacity after the 50th cycle relative to the discharge capacity after the first cycle, and this is shown in Table 2 below. In addition, the resistance increase rate was defined as the percentage of DICR obtained by dividing the voltage drop (ΔV) over 60 seconds by the current in the 50th discharge cycle relative to DCIR obtained by dividing the voltage drop (ΔV) over 60 seconds by the current in the first discharge cycle, and this is also shown in Table 2 below.

[0146] [Table 2]

[0147] Referring to Tables 1 and 2, it can be confirmed that the batteries containing the positive electrode active materials of Examples 1 to 4 contain Ni, Co, Mn, Al, Zr, and Y, satisfy Formula 1 as described herein, and exhibit excellent capacity, initial efficiency, lifespan, and resistance performance.

[0148] On the other hand, it can be confirmed that batteries containing the positive electrode active materials of Comparative Examples 1 to 3 have inferior initial discharge capacity, and their initial efficiency, lifespan, and resistance performance are all lower compared to the battery containing the positive electrode active material of Example 1. The positive electrode active material of Comparative Example 1 does not contain Y and has problems with grain growth, so it cannot satisfy Formula 1 as described herein, and the performance of batteries containing it is reduced. Also, the positive electrode active material of Comparative Example 2 does not contain Al and has a high defect rate and increased cation mixing, so the performance of batteries containing it is reduced. Furthermore, the positive electrode active material of Comparative Example 3 does not contain Zr, which improves particle strength, so it cannot satisfy Formula 1 as described herein, and the performance of batteries containing it is reduced.

Claims

1. It contains a lithium composite transition metal oxide in single-particle form, The lithium composite transition metal oxide comprises Ni, Co, Mn, Al, and M1. The aforementioned M1 is one or more selected from Zr, Y, K, Sr, and Ba. A positive electrode active material that satisfies the following equation 1. [Formula 1] ｜１－α／β｜≦０．１ In the above formula 1, α is (D ９０ -D １０ ) / D ５０ This is the value, and β is the positive electrode active material at 1,000 kgf / cm². ２ ~7,000kgf / cm ２ (D ９０ -D １０ ) / D ５０ This is the value.

2. The lithium composite transition metal oxide has a layered structure, wherein the positive electrode active material is as described in claim 1.

3. The lithium composite transition metal oxide has an average particle size (D ５０ ) of 3.00 μm to 8.00 μm, and the positive electrode active material according to claim 1.

4. The positive electrode active material according to claim 1, wherein the lithium composite transition metal oxide is doped with Al and M1.

5. 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.

6. The positive electrode active material according to claim 1, wherein M1 is present in an amount of 100 ppm to 5,000 ppm relative to the total weight of the lithium composite transition metal oxide.

7. 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.

8. 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 M1 ｅ M2 ｆ ]O ２－ｙ A ｙ In the aforementioned chemical formula 1, M1 is one or more selected from Zr, Y, K, Sr, and Ba. M2 is one or more selected from B, Ba, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo, W, and P. A is one or more elements selected from F, Cl, Br, I, and S. 1.0 ≤ x ≤ 1.3, 0.6 ≤ a < 1, 0.0 < b ≤ 0.4, 0.0 < c ≤ 0.4, 0.0 < d ≤ 0.01, 0.0 < e ≤ 0.005, 0.0 ≤ f ≤ 0.2, a + b + c + d + e + f = 1, 0 ≤ y ≤ 0.

2.

9. (A) A step of mixing a positive electrode active material precursor containing Ni, Co and Mn, an aluminum-containing raw material, an M1-containing raw material and a first lithium-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 800°C to 950°C, (C) The process includes the step of mixing a second lithium-containing raw material with the primary calcined product and then performing a secondary calcination at a temperature of 680°C to 850°C to produce a secondary calcined product. The aforementioned M1 is one or more selected from Zr, Y, K, Sr, and Ba. A method for producing a positive electrode active material, wherein the M1-containing raw material is mixed in an amount of 100 ppm to 5,000 ppm relative to the total weight of the positive electrode active material precursor.

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

13. The positive electrode according to claim 12, 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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