Cathode active material, and cathode and lithium secondary battery comprising same

Abstract

The present invention relates to a cathode active material in a single particle form capable of exhibiting optimal battery performance, and a cathode and a lithium secondary battery comprising same, the cathode active material comprising a lithium composite transition metal oxide, which has a composition represented by chemical formula 1 described in the present specification and is in a single particle form consisting of 10 or less primary particles, wherein the primary particles have a Dv,50 of 2.2 ㎛ to 3.7 ㎛ as derived from an SEM image and a small particle fraction of 5% to 10% according to Equation 1 described in the present specification.

Description

Cathode active material, cathode and lithium secondary battery containing same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0151123, filed November 3, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a cathode active material, a cathode including the same, and a lithium secondary battery, and more particularly, to a cathode active material in the form of a single particle, a cathode including the same, and a lithium secondary battery.

[0005]

[0006] With the recent technological development and increasing demand for mobile devices and electric vehicles, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which boast high energy density and voltage, long cycle life, and low self-discharge rates, are commercialized and widely used.

[0007] 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 for lithium secondary batteries, and recently, Li[Ni a Co b Mn c ]O2, Li[Ni a Co b Al c ]O2, Li[Ni a Co b Mn c Al d ] Lithium composite transition metal oxides containing two or more transition metals, such as O2, have been developed and are widely used.

[0008] Lithium composite transition metal oxides containing two or more transition metals developed to date are usually manufactured in the form of spherical secondary particles in which tens to hundreds of primary particles are aggregated. Recently, in order to solve the structural and thermal stability problems of the secondary particle-type positive electrode active material itself, the development of single-particle positive electrode active materials is accelerating. Specifically, when the secondary particle-type positive electrode active material is applied to a lithium secondary battery, there is a problem that a large amount of gas is generated, causing the volume of the battery to expand. In addition, when the nickel content in the positive electrode active material is increased for high capacity, the risk of fire also increases. Accordingly, the demand for the development of single-particle positive electrode active materials with excellent stability is increasing.

[0009] The single particle type positive electrode active material is a concept that contrasts with the spherical secondary particle type positive electrode active material formed by the agglomeration of tens to hundreds of primary particles manufactured by conventional methods, and is a positive electrode active material composed of 10 or fewer primary particles. Since the size of the primary particles in the single particle type positive electrode active material has a very large effect on the performance of the positive electrode active material, it is necessary to control it well.

[0010] Meanwhile, when manufacturing lithium secondary batteries using the above-mentioned single-particle positive electrode active material, cracking and collapse of the positive electrode active material particles can easily occur during the process of applying the positive electrode active material to the positive electrode collector and then rolling it. Consequently, during the charge / discharge process of the lithium secondary battery, gas is generated due to side reactions between the positive electrode active material and the electrolyte, and swelling occurs, which deteriorates battery characteristics.

[0011] Therefore, there is a need to develop a single particle type cathode active material that can exhibit optimal battery performance.

[0012]

[0013] The present invention is an invention to solve the above problems, and aims to provide a single particle type positive electrode active material capable of exhibiting optimal battery performance.

[0014] In addition, the present invention aims to provide a lithium secondary battery with improved performance, including the positive electrode active material.

[0015]

[0016] To solve the above problem, the present invention provides a positive electrode active material, a positive electrode, and a lithium secondary battery.

[0017]

[0018] (1) The present invention comprises a lithium composite transition metal oxide in the form of a single particle consisting of 10 or fewer primary particles, having a composition represented by the following chemical formula 1, wherein the primary particles have a D derived from an SEM image. v,50 This provides a positive electrode active material having a particle size of 2.2 μm to 3.7 μm and a particle ratio of 5% to 10% according to the following formula 1.

[0019] [Chemical Formula 1]

[0020] Li 1+x Ni a1 Co b1 Mn c1 Zr d1 Y e1 M f1 O 2-y A y

[0021] In the above chemical formula 1,

[0022] M is at least one selected from W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si, and Al,

[0023] A is at least one selected from F, Cl, Br, I, and S,

[0024] -0.1≤x≤0.1, 0 <a1<1, 0<b1<1, 0<c1<1, 0<d1<0.01, 0<e1<0.01, 0≤f1<0.1, 0≤y≤0.2, a1+b1+c1+d1+e1+f1=1이고,

[0025] [Formula 1]

[0026] Small particle ratio (%) = (sum of the area of ​​primary particles with a particle size of 1 μm or less derived from SEM images / sum of the area of ​​all primary particles derived from SEM images) × 100.

[0027] (2) In the present invention, in the above (1), the primary particle is D derived from the SEM image. v,50 This provides a positive electrode active material having a diameter of 2.5㎛ to 2.8㎛.

[0028] (3) In the present invention, in the above (1) or (2), the positive electrode active material has a D measured by PSA (particle size analyzer). 50 This provides a positive electrode active material having a diameter of 3.5㎛ to 4㎛.

[0029] (4) The present invention provides a positive electrode active material in any one of the above (1) to (3), wherein the lithium composite transition metal oxide is doped with 1000 ppm to 4000 ppm of Zr and 1000 ppm to 4000 ppm of Y.

[0030] (5) The present invention provides a positive electrode active material according to any one of the above (1) to (4), wherein the positive electrode active material further includes a coating layer formed on the lithium composite transition metal oxide, and the coating layer includes Al, W, or a combination thereof.

[0031] (6) The present invention provides a positive electrode comprising a positive electrode active material according to any one of (1) to (5).

[0032] (7) The present invention provides a lithium secondary battery comprising a positive electrode according to (6); a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte.

[0033]

[0034] The cathode active material of the present invention comprises a lithium composite transition metal oxide doped with Zr and Y, and the particle ratio and the particle size of the primary particles according to Equation 1 described herein satisfy a specific range, thereby improving particle breakage and improving the capacity, initial efficiency, resistance performance, etc. of a lithium secondary battery.

[0035] The cathode and lithium secondary battery according to the present invention may have excellent capacity, initial efficiency, resistance performance, etc.

[0036]

[0037] Figure 1 is a SEM image of the positive electrode active material of Example 1.

[0038] Figure 2 is a SEM image of the positive electrode active material of Example 3.

[0039]

[0040] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0041] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0042]

[0043] It should be understood that the terms “include,” “have,” or “have” used in this specification are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0044] In this specification, the term 'on' means not only when a configuration is formed directly on the top surface of another configuration, but also when a third configuration is interposed between these configurations.

[0045] In this specification, the term "single particle form" refers to a form composed of 10 or fewer primary particles, in contrast to the spherical secondary particle form formed by agglomeration of tens to hundreds of primary particles manufactured by conventional methods. Specifically, the single particle form in the present invention may be a single particle composed of one primary particle, or may be a secondary particle form in which 2 to 10 primary particles are agglomerated.

[0046] 'Primary particle' refers to the smallest particle unit recognized when observing a positive electrode active material through a scanning electron microscope, and 'secondary particle' refers to a secondary structure formed by the aggregation of multiple primary particles.

[0047] In this specification, the term 'D of primary particles derived from SEM images v,50 'The area of ​​each primary particle is calculated through the number of pixels corresponding to each of n (at least 50) primary particles present in a specific magnification (e.g., 5,000x, 8,000x) image among SEM images, and the diameter and volume of each primary particle present in the SEM image are calculated using the radius value of a circle having the same area as the area of ​​each primary particle, and the particle diameter at the point where the cumulative volume distribution according to the particle diameter is 50% is calculated.

[0048] In this specification, the term 'sum of the area of ​​primary particles having a particle size of 1 μm or less derived from an SEM image' can be obtained by calculating the area of ​​each primary particle through the number of pixels corresponding to each of n (at least 50 or more) primary particles present in an image at a specific magnification (e.g., 5,000 times, 8,000 times) among SEM images, obtaining the particle size of each primary particle present in the SEM image using the radius value of a circle having the same area as the area of ​​each primary particle, and adding the areas of primary particles having a particle size of 1 μm or less among the primary particles.

[0049] In this specification, the term 'sum of the area of ​​all primary particles derived from the SEM image' can be obtained by calculating the area of ​​each primary particle through the number of pixels corresponding to each of n (at least 50 or more) primary particles present in an image of a specific magnification (e.g., 5,000x, 8,000x) among SEM images, obtaining the particle size of each primary particle present in the SEM image using the radius value of a circle having the same area as the area of ​​each primary particle, and adding the areas of all primary particles.

[0050] In this specification, 'D measured by PSA (particle size analyzer) 50 ' means the particle size at the 50% point of the cumulative volume distribution according to particle size. The above D 50 The powder to be measured is dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac's S3500), and the particle size distribution is calculated by measuring the difference in diffraction patterns according to particle size when the particles pass through the laser beam, and the particle diameter at the point where it becomes 50% of the volume cumulative distribution according to particle size in the measuring device is calculated, thereby allowing measurement.

[0051]

[0052] positive electrode active material

[0053] The present invention comprises a lithium composite transition metal oxide in the form of a single particle consisting of 10 or fewer primary particles, having a composition represented by the following chemical formula 1, wherein the primary particles have a D derived from an SEM image. v,50 This provides a cathode active material having a particle size of 2.2 μm to 3.7 μm and a particle ratio of 5% to 10% according to the following formula 1. The lithium composite transition metal oxide may have a layered structure.

[0054] [Chemical Formula 1]

[0055] Li 1+x Ni a1 Co b1 Mn c1 Zr d1 Y e1 M f1 O 2-y A y

[0056] In the above chemical formula 1,

[0057] M is at least one selected from W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si, and Al,

[0058] A is at least one selected from F, Cl, Br, I, and S,

[0059] -0.1≤x≤0.1, 0 <a1<1, 0<b1<1, 0<c1<1, 0<d1<0.01, 0<e1<0.01, 0≤f1<0.1, 0≤y≤0.2, a1+b1+c1+d1+e1+f1=1이고,

[0060] [Formula 1]

[0061] Small particle ratio (%) = (sum of the area of ​​primary particles with a particle size of 1 μm or less derived from SEM images / sum of the area of ​​all primary particles derived from SEM images) × 100.

[0062]

[0063] The present inventors have found that when a cathode active material comprises a lithium composite transition metal oxide in the form of a single particle doped with Zr and Y, the particle size of the primary particle satisfies a specific range, and the small particle ratio according to Equation 1 described herein is 5% to 10%, the cathode active material particles are less likely to break during rolling for manufacturing a lithium secondary battery, thereby improving the capacity, initial efficiency, and resistance performance of the lithium secondary battery, and have completed the present invention.

[0064]

[0065] According to the present invention, the lithium composite transition metal oxide is doped with Zr and Y. In this case, Zr is stably doped into the transition metal layer, so that a stable structure can be maintained even when lithium is inserted and removed repeatedly through repeated charge and discharge. In addition, Y acts as a flux material during sintering, so that an optimal primary particle size can be realized even at relatively low temperatures, which is advantageous for resistance and rate characteristics.

[0066] Meanwhile, if the lithium composite transition metal oxide is not doped with Zr, the structural retention rate is low, resulting in poor life performance, and if it is not doped with Y, the sintering temperature must be further increased to achieve an optimal primary particle size, resulting in poor resistance and rate characteristics.

[0067] According to the present invention, the lithium composite transition metal oxide may be doped with 1,000 ppm to 4,000 ppm of Zr and 1,000 ppm to 4,000 ppm of Y to have the desired primary particle size and optimal performance in terms of lifespan and resistance.

[0068] The content of Zr may be specifically 1,000 ppm or more, 1,100 ppm or more, 1,200 ppm or more, 1,300 ppm or more, or 1,400 ppm or more, and 1,500 ppm or less, 1,600 ppm or less, 1,700 ppm or less, 1,800 ppm or less, 1,900 ppm or less, 2,000 ppm or less, 2,100 ppm or less, 2,200 ppm or less, 2,300 ppm or less, 2,400 ppm or less, 2,500 or less, 2,600 or less, 2,700 or less, 2,800 or less, 2,900 or less, 3,000 ppm or less, 3,100 ppm or less, 3,200 ppm or less, It may be 3,300 ppm or less, 3,400 ppm or less, 3,500 ppm or less, 3,600 ppm or less, 3,700 ppm or less, 3,800 ppm or less, 3,900 ppm or less, or 4,000 ppm or less.

[0069] The content of Y may be specifically 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, 1,500 ppm or more, 1,600 ppm or more, 1,700 ppm or more, 1,800 ppm or more, 1,900 ppm or more, 2,000 ppm or more, 2,100 ppm or more, 2,200 ppm or more, 2,300 ppm or more, 2,400 ppm or more, 2,500 ppm or more, 2,600 ppm or more, 2,700 ppm or more, 2,800 ppm or more, or 2,900 ppm or more, and 3,000 ppm or less, 3,100 ppm or less, It may be 3,200 ppm or less, 3,300 ppm or less, 3,400 ppm or less, 3,500 ppm or less, 3,600 ppm or less, 3,700 ppm or less, 3,800 ppm or less, 3,900 ppm or less, or 4,000 ppm or less.

[0070] When the content of Zr is within the above range, high capacity can be realized while maintaining excellent structural retention rate during charge and discharge, and when the content of Y is within the above range, an optimal primary particle size can be realized even at a relatively low temperature, so that high capacity can be realized while being advantageous in resistance or rate characteristics.

[0071]

[0072] According to the present invention, the positive electrode active material has a particle ratio of 5% to 10% according to Equation 1. When the particle ratio is 5% to 10%, it has optimal performance in terms of battery performance, particle breakage, and rolling density.

[0073] Meanwhile, if the particle size ratio of the positive electrode active material is less than 5%, there are problems with the efficiency and resistance performance of the battery, and if it exceeds 10%, there are problems with particle breakage and poor rolling density.

[0074]

[0075] According to the present invention, the primary particle is D derived from the SEM image. v,50 This may be 2.2㎛ to 3.7㎛, preferably 2.5㎛ to 2.8㎛. In this case, it has optimal performance in terms of battery performance, particle breakage, and rolling density. Meanwhile, the D of the primary particles v,50 If it is less than 2.2㎛, there is a problem that the rolling density and / or the life performance of the battery are inferior, and if it is more than 3.7㎛, there is a problem that the efficiency and / or resistance performance of the battery are inferior.

[0076] D of the above primary particle v,50 When manufacturing a positive electrode active material, it can be controlled by the type and content of the doping element, the amount of lithium raw material added, the sintering temperature, etc.

[0077]

[0078] According to the present invention, the positive electrode active material has a D measured by PSA (particle size analyzer) 50This may be 3.5㎛ to 4.0㎛. D of the positive electrode active material 50 Specifically, it can be 3.50㎛ or more, 3.80㎛ or less, 3.85㎛ or less, 3.90㎛ or less, 3.95㎛ or less, or 4.0㎛ or less. D measured by PSA (particle size analyzer) of the positive electrode active material 50 Within this range, both the life and capacity characteristics of the battery including it are improved, and the electrochemical performance can be optimized. For reference, D 50 If it is less than 3.5㎛, the battery life may be reduced, and if it is more than 4.0㎛, the battery capacity may be reduced.

[0079]

[0080] According to the present invention, 3 g of the positive electrode active material is placed in a mold having an inner diameter of 13 mm and pressurized at 9 tons for 1 minute, and then the ratio of the number of particles having a particle size of less than 1 μm as measured by a PSA (particle size analyzer) to the total number of particles (the amount of fine particles generated) may be 2.5% or less, specifically 2.0% or less, 1.5% or less, 1.0% or less, or 0.6% or less. In this case, since the specific surface area where the particles come into contact with the electrolyte is reduced, side reactions can be suppressed, and the capacity retention rate (lifespan) and gas generation according to charge and discharge can be improved.

[0081]

[0082] According to the present invention, the lithium composite transition metal oxide may contain nickel in an amount of 60 mol% or more based on the total molar number of metals excluding lithium. That is, 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 a lithium secondary battery can be improved.

[0083] According to the present invention, in the chemical formula 1, x may be -0.1 or more, -0.09 or more, -0.08 or more, -0.07 or more, -0.06 or more, -0.05 or more, -0.04 or more, -0.03 or more, -0.02 or more, -0.01 or more, or 0 or more, and may be 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, or 0.1 or less. When x satisfies the above range, high-capacity characteristics and high energy density per unit volume can be realized.

[0084] According to the present invention, in the chemical formula 1, a1 means the atomic fraction of nickel among the metal elements in the lithium composite transition metal oxide, and may be 0.6 or more, 0.61 or more, or 0.62 or more, and 0.7 or less, 0.71 or less, 0.72 or less, 0.73 or less, 0.74 or less, 0.75 or less, 0.76 or less, 0.77 or less, 0.78 or less, 0.79 or less, 0.8 or less, 0.81 or less, 0.82 or less, 0.83 or less, 0.84 or less, 0.85 or less, 0.86 or less, 0.87 or less, 0.88 or less, 0.89 or less, 0.9 or less, 0.91 or less, 0.92 or less, 0.93 or less, 0.94 or less, 0.95 or less, 0.96 or less, It may be 0.97 or less, 0.98 or less, 0.99 or less, or less than 1. When a1 satisfies the above range, high-capacity characteristics can be implemented, and in particular, when a1 is 0.6 to 0.75, high energy density can be exhibited when driven at high voltage, thereby implementing high-capacity characteristics.

[0085] According to the present invention, in the chemical formula 1, b1 means the atomic fraction of cobalt among the metal elements in the lithium composite transition metal oxide, and may be greater than 0, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more, and may be 0.10 or less, 0.11 or less, 0.12 or less, 0.13 or less, 0.14 or less, 0.15 or less, 0.16 or less, 0.17 or less, 0.18 or less, 0.19 or less, 0.20 or less, 0.21 or less, 0.22 or less, 0.23 or less, 0.24 or less, 0.25 or less, 0.26 or less, 0.27 or less, 0.28 or less, 0.29 or less, 0.30 or less, 0.31 or less, 0.32 or less, 0.33 b1 may be less than, 0.34 or less, 0.35 or less, 0.36 or less, 0.37 or less, 0.38 or less, 0.39 or less, or less than 0.4. When b1 satisfies the above range, stability can be improved and rate characteristics can be enhanced during the charge and discharge process.

[0086] According to the present invention, in the chemical formula 1, c1 means the atomic fraction of manganese among the metal elements in the lithium composite transition metal oxide, and is greater than 0, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, 0.15 or more, 0.16 or more, 0.17 or more, 0.18 or more, 0.19 or more, 0.2 or more, 0.21 or more, 0.22 or more, 0.23 or more, 0.24 or more, 0.25 or more, 0.26 or more, 0.27 or more, 0.28 or more, 0.29 or more, or It can be 0.30 or more, 0.32 or less, 0.33 or less, 0.34 or less, 0.35 or less, 0.36 or less, 0.37 or less, 0.38 or less, 0.39 or less, or less than 0.4. When c1 satisfies the above range, high-capacity characteristics can be realized. In addition, high-temperature stability can be increased, and side reactions with the electrolyte can be relatively reduced.

[0087] According to the present invention, in the chemical formula 1, d1 refers to the atomic fraction of zirconium among the metal elements in the lithium composite transition metal oxide, and may be 0 or more, or 0.0005 or more, and may be 0.001 or less, 0.002 or less, 0.003 or less, 0.004 or less, 0.005 or less, 0.006 or less, 0.007 or less, 0.008 or less, 0.009 or less, or 0.01 or less. When d1 satisfies the above range, the stability of the crystal structure of the positive electrode active material is improved, and the resistance and lifespan of the battery can be improved due to the increased structural stability.

[0088] According to the present invention, in the chemical formula 1, e1 refers to the atomic fraction of yttrium among the metal elements in the lithium composite transition metal oxide, and may be 0 or more, or 0.001 or more, and may be 0.002 or less, 0.003 or less, 0.004 or less, 0.005 or less, 0.006 or less, 0.007 or less, 0.008 or less, 0.009 or less, or 0.01 or less. When e1 satisfies the above range, particle growth properties may be improved, thereby improving capacity and lifespan.

[0089] According to the present invention, in the chemical formula 1, f1 refers to the atomic fraction of the M element among the metal elements in the lithium composite transition metal oxide, and may be 0 or more, and may be 0.01 or less, 0.02 or less, 0.03 or less, 0.04 or less, 0.05 or less, 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, or 0.10 or less. When f1 satisfies the above range, the stability of the crystal structure of the positive electrode active material can be improved and the grain shape can be improved.

[0090]

[0091] According to the present invention, the positive electrode active material further includes a coating layer formed on the lithium composite transition metal oxide, and the coating layer may include Al, W, or a combination thereof. In this case, the capacity and lifespan of a battery including the positive electrode active material may have optimal performance.

[0092] According to the present invention, the content of Al included in the coating layer may be 1,000 ppm to 2,000 ppm relative to the total weight of the positive electrode active material. Specifically, the content of Al may be 1,000 ppm or more, 1,100 ppm or more, 1,200 ppm or more, 1,300 ppm or more, or 1,400 ppm or more, and may be 1,500 ppm or less, 1,600 ppm or less, 1,700 ppm or less, 1,800 ppm or less, 1,900 ppm or less, or 2,000 ppm or less relative to the total weight of the positive electrode active material. In this case, the electrical conductivity of the positive electrode active material is improved, and the generation of byproducts formed by side reactions with the electrolyte in the battery is suppressed, so that the capacity characteristics, resistance characteristics, and life characteristics of the positive electrode active material can be improved.

[0093] According to the present invention, the content of W included in the coating layer may be 2,000 ppm to 4,000 ppm relative to the total weight of the positive electrode active material. The content of W may be specifically 2,000 ppm or more, 2,100 ppm or more, 2,200 ppm or more, 2,300 ppm or more, 2,400 ppm or more, 2,500 ppm or more, 2,600 ppm or more, 2,700 ppm or more, 2,800 ppm or more, or 2,900 ppm or more, and 3,000 ppm or less, 3,100 ppm or less, 3,200 ppm or less, 3,300 ppm or less, 3,400 ppm or less, 3,500 ppm or less, 3,600 ppm or less, 3,700 ppm or less, 3,800 ppm or less, 3,900 or less, or 4,000 ppm or less, based on the total weight of the positive electrode active material. In this case, the electrical conductivity of the positive electrode active material is improved, and the generation of by-products formed by side reactions with the electrolyte in the battery is suppressed, so that the capacity characteristics, resistance characteristics, and life characteristics of the positive electrode active material can be improved.

[0094]

[0095] Method for manufacturing positive electrode active material

[0096] The positive electrode active material according to the present invention can be manufactured by the following method for manufacturing a positive electrode active material, but is not limited thereto.

[0097] A method for producing a single-particle type positive electrode active material according to the present invention comprises the steps of (A) mixing a positive electrode active material precursor having a composition represented by the following chemical formula 2, a zirconium-containing raw material, a yttrium-containing raw material, and a lithium-containing raw material to produce a mixture; and (B) firing the mixture successively in an air atmosphere at 600°C to 850°C for the first time, at 960°C to 970°C for the second time, and at 500°C to 850°C for the third time to produce a fired product.

[0098] [Chemical Formula 2]

[0099] Ni a2 Co b2 Mn c2 M 1 d2 (OH)2

[0100] In the above chemical formula 2,

[0101] M 1 is at least one selected from Zr, Y, W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al,

[0102] 0 <a2<1, 0<b2<1, 0<c2<1, 0≤d2<0.1, a2+b2+c2+d2=1이다.

[0103]

[0104] The present inventors have found that when the mixture of a zirconium-containing raw material, an yttrium-containing raw material, and a lithium-containing raw material is sequentially fired at 800°C to 900°C for the first time, fired at 940°C to 970°C for the second time, and fired at 550°C to 650°C for the third time, a positive electrode active material having a uniform particle size is produced, and the positive electrode active material particles are less likely to break during rolling for manufacturing a lithium secondary battery, thereby completing the present invention.

[0105]

[0106] (A) Step

[0107] The above step (A) is a step of preparing a mixture by mixing a positive electrode active material precursor having a composition represented by the above chemical formula 2, a zirconium-containing raw material, a yttrium-containing raw material, and a lithium-containing raw material.

[0108]

[0109] According to the present invention, the positive electrode active material precursor may contain nickel (Ni) in an amount of 60 mol% or more relative to the total molar number of transition metals contained in the positive electrode active material precursor. In this case, the energy density of a lithium secondary battery can be improved.

[0110] According to the present invention, in the chemical formula 2, a2 ​​means the atomic fraction of nickel among the metal elements in the composite transition metal hydroxide, and may be 0.6 or more, 0.61 or more, or 0.62 or more, and 0.7 or less, 0.71 or less, 0.72 or less, 0.73 or less, 0.74 or less, 0.75 or less, 0.76 or less, 0.77 or less, 0.78 or less, 0.79 or less, 0.8 or less, 0.81 or less, 0.82 or less, 0.83 or less, 0.84 or less, 0.85 or less, 0.86 or less, 0.87 or less, 0.88 or less, 0.89 or less, 0.9 or less, 0.91 or less, 0.92 or less, 0.93 or less, 0.94 or less, 0.95 or less, 0.96 or less, 0.97 or less, 0.98 or less, 0.99 or less, or less than 1. When a2 satisfies the above range, a high-capacity characteristic of a battery including a positive electrode active material produced as a result can be realized, and in particular, when a2 is 0.6 to 0.75, a battery including a positive electrode active material produced as a result can exhibit a high energy density when driven at a high voltage, thereby realizing a high-capacity characteristic.

[0111] According to the present invention, in the chemical formula 2, the b2 means the atomic fraction of cobalt among the metal elements in the complex transition metal hydroxide, and may be greater than 0, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more, and may be 0.10 or less, 0.11 or less, 0.12 or less, 0.13 or less, 0.14 or less, 0.15 or less, 0.16 or less, 0.17 or less, 0.18 or less, 0.19 or less, 0.20 or less, 0.21 or less, 0.22 or less, 0.23 or less, 0.24 or less, 0.25 or less, 0.26 or less, 0.27 or less, 0.28 or less, 0.29 or less, 0.30 or less, 0.31 or less, 0.32 or less, It may be 0.33 or less, 0.34 or less, 0.35 or less, 0.36 or less, 0.37 or less, 0.38 or less, 0.39 or less, or less than 0.4. When b2 satisfies the above range, the stability of the battery including the resulting positive electrode active material may be improved and the rate characteristics may be enhanced during the charge and discharge process.

[0112] According to the present invention, in the chemical formula 2, c2 means the atomic fraction of manganese among the metal elements in the composite transition metal hydroxide, and is greater than 0, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, 0.15 or more, 0.16 or more, 0.17 or more, 0.18 or more, 0.19 or more, 0.2 or more, 0.21 or more, 0.22 or more, 0.23 or more, 0.24 or more, 0.25 or more, 0.26 or more, 0.27 or more, 0.28 or more, 0.29 or more, or It can be 0.30 or more, 0.32 or less, 0.33 or less, 0.34 or less, 0.35 or less, 0.36 or less, 0.37 or less, 0.38 or less, 0.39 or less, or less than 0.4. When c2 satisfies the above range, a high-capacity characteristic of a battery including the resulting positive electrode active material can be realized. In addition, the high-temperature stability of the battery can be increased, and side reactions with the electrolyte can be relatively reduced.

[0113] According to the present invention, in the chemical formula 2, d2 is M among the metal elements in the complex transition metal hydroxide. 1 Refers to the atomic fraction of an element, and may be 0 or more, 0.01 or less, 0.02 or less, 0.03 or less, 0.04 or less, 0.05 or less, 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, or 0.10 or less. When d2 satisfies the above range, the crystal structure stability of the resulting positive electrode active material may be improved and the grain shape may be improved.

[0114]

[0115] According to the present invention, the lithium-containing raw material may be lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide or oxyhydroxide, and is not particularly limited as long as it can be dissolved in water. Specifically, the lithium-containing raw material may be Li2CO3, LiNO3, LiNO2, LiOH, LiOHㆍH2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, or Li3C6H5O7, and any one of these or a mixture of two or more thereof may be used.

[0116] According to the present invention, the positive electrode active material precursor and the lithium-containing raw material can be mixed so that the ratio (M:Li) of the total mole number (M) of transition metals included in the positive electrode active material precursor and the mole number (Li) of lithium included in the lithium-containing raw material is 1:1.03 to 1.07. In this case, the positive electrode active material produced as a result can have the desired primary particle size, and the lifespan and resistance characteristics of the battery can be improved.

[0117]

[0118] According to the present invention, the zirconium (Zr)-containing raw material is Zr(OH)4, ZrO2, Zr(NO3)4, ZrCl4, ZrS2, Zr(SO4)2 and C8H 12 It may be at least one selected from O8Zr, specifically at least one selected from ZrO2, Zr(OH)4 and Zr(NO3)4, and more specifically ZrO2.

[0119] According to the present invention, the zirconium-containing raw material can be added in an amount such that zirconium is 1,000 ppm to 4,000 ppm based on the total weight of the positive electrode active material precursor. Specifically, the zirconium-containing raw material contains zirconium in an amount of 1,000 ppm or more, 1,100 ppm or more, 1,200 ppm or more, 1,300 ppm or more, or 1,400 ppm or more, and 1,500 ppm or less, 1,600 ppm or less, 1,700 ppm or less, 1,800 ppm or less, 1,900 ppm or less, 2,000 ppm or less, 2,100 ppm or less, 2,200 ppm or less, 2,300 ppm or less, 2,400 ppm or less, 2,500 or less, 2,600 or less, 2,700 or less, 2,800 or less, 2,900 or less, 3,000 ppm or less, 3,100 ppm or less, relative to the total weight of the composite transition metal hydroxide. It can be added in an amount such that the content is 3,200 ppm or less, 3,300 ppm or less, 3,400 ppm or less, 3,500 ppm or less, 3,600 ppm or less, 3,700 ppm or less, 3,800 ppm or less, 3,900 ppm or less, or 4,000 ppm or less. In this case, Zr is stably doped into the transition metal layer, so that a stable structure can be maintained even when charge and discharge are repeated and lithium is inserted and removed repeatedly.

[0120] According to the present invention, the yttrium (Y)-containing raw material may be at least one selected from among YCl3, Y2O3, Y(NO3)3, Y(OH)3, YSZ, Y2(SO4)3 and Y2S3, specifically, at least one selected from among Y2O3, Y(OH)3 and YSZ, and more specifically, Y2O3.

[0121] According to the present invention, the yttrium-containing raw material can be added in an amount such that yttrium is 1,000 ppm to 4,000 ppm based on the total weight of the positive electrode active material precursor. Specifically, the yttrium-containing raw material contains yttrium in an amount of 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, 1,500 ppm or more, 1,600 ppm or more, 1,700 ppm or more, 1,800 ppm or more, 1,900 ppm or more, 2,000 ppm or more, 2,100 ppm or more, 2,200 ppm or more, 2,300 ppm or more, 2,400 ppm or more, 2,500 ppm or more, 2,600 ppm or more, 2,700 ppm or more, 2,800 ppm or more, or 2,900 ppm or more, and 3,000 ppm or less, relative to the total weight of the composite transition metal hydroxide. It can be added in an amount such that the content is 3,100 ppm or less, 3,200 ppm or less, 3,300 ppm or less, 3,400 ppm or less, 3,500 ppm or less, 3,600 ppm or less, 3,700 ppm or less, 3,800 ppm or less, 3,900 ppm or less, or 4,000 ppm or less. In this case, Y acts as a plus (flux) material during firing, so that the optimal primary particle size can be realized even at a relatively low temperature, which is advantageous for resistance or rate characteristics.

[0122]

[0123] (B) Step

[0124] The above step (B) is a step of manufacturing a sintered product by successively firing the mixture at 600°C to 850°C for the first time, at 960°C to 970°C for the second time, and at 500°C to 850°C for the third time in an air atmosphere.

[0125]

[0126] According to the present invention, when the mixture is first fired at 600°C to 850°C, the lithium-containing raw material melts and is sufficiently uniformly distributed on the surface of the precursor, thereby effectively reacting the lithium and the precursor to produce an active material having a uniform primary particle shape. Specifically, the first firing temperature may be 600°C or higher, 650°C or higher, 700°C or higher, or 750°C or higher, and 800°C or lower, or 850°C or lower. When the first firing temperature is within the above range, the lithium-containing raw material melts and can be sufficiently uniformly distributed on the surface of the precursor. On the other hand, when the first firing temperature is less than 600°C, there is a problem that the lithium-containing raw material does not melt sufficiently, and when it exceeds 850°C, the lithium-containing raw material intercalates into the precursor before melting and being sufficiently uniformly distributed, thereby producing an active material having a relatively non-uniform shape.

[0127] According to the present invention, the primary firing is performed under an air atmosphere in order to uniformly distribute the lithium-containing raw material.

[0128] According to the present invention, the first firing may be performed for 1 to 8 hours. In this case, the lithium-containing raw material can be melted and distributed sufficiently and evenly on the surface of the precursor.

[0129]

[0130] Immediately after the first firing is completed, the temperature is continuously increased to 960°C to 970°C, and when the second firing is performed at 960°C to 970°C, lithium is intercalated into the precursor to form a layered structure, and the primary particle interfaces merge to cause the primary particles to grow. When the second firing temperature is within the above range, the optimal primary particle size can be realized, so that the optimal performance of the battery capacity, resistance, and lifespan, as well as particle breakage and rolling density, can be expressed. On the other hand, when the second firing temperature is less than 960°C, the size of the primary particles becomes small, which causes problems in terms of particle breakage and rolling density, and when it exceeds 970°C, the primary particle size becomes large, which causes problems in terms of efficiency and resistance performance.

[0131] The above secondary firing is performed under an air atmosphere in order to ensure proper growth of the primary particles.

[0132] According to the present invention, the secondary calcination may be performed for 3 to 12 hours. In this case, lithium is sufficiently intercalated into the precursor, and primary particle growth can also occur appropriately.

[0133]

[0134] Immediately after the above-mentioned second firing is completed, the temperature is continuously increased to 500°C to 850°C, and a third firing is performed at 500°C to 850°C, so that defects in the crystal structure of the active material that are generated by the high temperature of the second firing are alleviated, and a fired product with fewer structural defects is manufactured. The above-mentioned third firing temperature may specifically be 500°C or higher, 510°C or higher, 520°C or higher, 530°C or higher, 540°C or higher, 550°C or higher, 560°C or higher, 570°C or higher, 580°C or higher, 590°C or higher, or 600°C or higher, and 650°C or lower, 660°C or lower, 670°C or lower, 680°C or lower, 690°C or lower, 700°C or lower, 710°C or lower, 720°C or lower, 730°C or lower, 740°C or lower, 750°C or lower, 760°C or lower, 770°C or lower, 780°C or lower, 790°C or lower, 800°C or lower, 810°C or lower, 820°C or lower, 830°C or lower, 840°C or lower, or 850°C or lower. At this time, the sintered product is a lithium composite transition metal oxide in the form of a single particle. When the third sintering temperature is within the above range, structural defects can be effectively alleviated. On the other hand, when the third sintering temperature is below 500°C or above 850°C, structural defects are not effectively alleviated.

[0135] The above 3rd firing is performed under an air atmosphere in order to minimize structural defects.

[0136] According to the present invention, the third firing may be performed for 1 to 8 hours. In this case, defects within the crystal structure can be minimized.

[0137]

[0138] The method for manufacturing a cathode active material according to the present invention may further include (C) a step of pulverizing the sintered product, in order to effectively manufacture an electrode and to efficiently react at the active material-electrolyte interface. The pulverization may be performed by measuring D of the cathode active material using a PSA (particle size analyzer). 50This may be performed to be 3.5㎛ to 4.0㎛.

[0139] According to the present invention, the above-mentioned fine grinding may be performed by air-flow grinding. In this case, not only is the grinding efficiency superior to conventional physical grinding, but also, since no heat is generated, denaturation of the active material surface can be suppressed.

[0140] According to the present invention, the airflow grinding may be performed under a pressure of 1 bar to 5 bar. In this case, the target particle size can be effectively achieved.

[0141]

[0142] The method for manufacturing a cathode active material according to the present invention may further include the step of (C') mixing the sintered product with at least one selected from an aluminum raw material and a tungsten raw material and then performing a heat treatment to form a coating layer including at least one selected from Al and W on the sintered product. In this case, a coating portion including at least one selected from Al and W is formed on the sintered product (lithium composite transition metal oxide in the form of single particles).

[0143]

[0144] According to the present invention, the aluminum raw material may be at least one selected from Al2O3, Al(OH)3, AlCl3, AlF3 and Al2(SO4)3, specifically at least one selected from Al2O3, Al(OH)3 and AlF3, and more specifically Al2O3.

[0145] According to the present invention, the aluminum raw material may be added in an amount such that aluminum is 1,000 ppm to 2,000 ppm relative to the total weight of the sintered product. Specifically, the aluminum raw material may be added in an amount such that aluminum is 1,000 ppm or more, 1,100 ppm or more, 1,200 ppm or more, 1,300 ppm or more, or 1,400 ppm or more, and 1,500 ppm or less, 1,600 ppm or less, 1,700 ppm or less, 1,800 ppm or less, 1,900 ppm or less, or 2,000 ppm or less relative to the total weight of the sintered product.

[0146] In this case, the capacity retention rate according to charge and discharge can be improved.

[0147] According to the present invention, the tungsten raw material may be at least one selected from WO3, WC and H2WO4, and more specifically, may be WO3.

[0148] According to the present invention, the tungsten raw material may be added in an amount such that tungsten is 2,000 ppm to 4,000 ppm relative to the total weight of the sintered product. Specifically, the tungsten raw material may be added in an amount such that the tungsten content is 2,000 ppm or more, 2,100 ppm or more, 2,200 ppm or more, 2,300 ppm or more, 2,400 ppm or more, 2,500 ppm or more, 2,600 ppm or more, 2,700 ppm or more, 2,800 ppm or more, or 2,900 ppm or more, and 3,000 ppm or less, 3,100 ppm or less, 3,200 ppm or less, 3,300 ppm or less, 3,400 ppm or less, 3,500 ppm or less, 3,600 ppm or less, 3,700 ppm or less, 3,800 ppm or less, 3,900 or less, or 4,000 ppm or less, based on the total weight of the sintered product. In this case, output performance can be improved when the battery is driven.

[0149]

[0150] According to the present invention, the heat treatment can be performed at 400°C to 600°C. In this case, the life performance of the positive electrode active material can be further improved.

[0151] According to the present invention, the heat treatment can be performed under an air atmosphere in terms of surface stabilization.

[0152] According to the present invention, the heat treatment may be performed for 3 to 12 hours. In this case, by stabilizing the surface of the positive electrode active material, side reactions between the positive electrode active material and the electrolyte are suppressed as charge and discharge are repeated, thereby improving the battery's life performance.

[0153]

[0154] anode

[0155] The present invention provides a positive electrode comprising the positive electrode active material.

[0156] 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.

[0157] The positive electrode current collector may include a highly conductive metal, and is not particularly limited as long as it is easily adhered to by the positive electrode active material layer and does not react within the voltage range of the battery. The positive electrode current collector may be made of, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. In addition, the positive electrode current collector may typically have a thickness of 3 ㎛ to 500 ㎛, and fine unevenness may be formed on the surface of the current collector to increase the adhesion of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0158] The above-described positive electrode active material layer may optionally include a conductive material and a binder, together with the positive electrode active material, as needed. In this case, the positive electrode active material may be included in an amount of 80 wt% to 99 wt%, more specifically 85 wt% to 98.5 wt%, based on the total weight of the positive electrode active material layer, and excellent capacity performance may be exhibited within this range.

[0159] The conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. 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 or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One of these may be used alone or a mixture of two or more may be used. The conductive material may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0160] The above binder serves to improve 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), polyvinylalcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and polymers in which hydrogens of these are substituted with Li, Na, or Ca, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The above binder may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0161] The positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the positive electrode active material described above is used. Specifically, the positive electrode can be manufactured by applying a composition for forming a positive electrode active material layer, which is manufactured by dissolving or dispersing the positive electrode active material and optionally a binder, a conductive agent, and a dispersant in a solvent as needed, onto a positive electrode current collector, followed by drying and rolling, or by casting the composition for forming a positive electrode active material layer onto a separate support, peeling the film from the support, and laminating the resulting film onto a positive electrode current collector.

[0162] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant in consideration of the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0163]

[0164] lithium secondary battery

[0165] The present invention provides a lithium secondary battery comprising: the positive electrode; the negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte.

[0166]

[0167] The lithium secondary battery may optionally further include a battery container that houses the electrode assembly of the positive electrode, negative electrode, and separator, and a sealing member that seals the battery container.

[0168]

[0169] The above negative electrode may include a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0170] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 ㎛ to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0171] The above negative electrode active material layer may optionally include a binder and a conductive material together with the negative electrode active material.

[0172] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may 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 alloy, Sn alloy, or Al alloy; SiO β(0<β<2), SnO2, vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical or fibrous shapes, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes. The negative electrode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0173] The binder of the above-described negative electrode active material layer is a component that assists in bonding between the conductive material, the active material, and the current collector, and is typically added in an amount of 0.1 wt% to 10 wt% based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0174] The conductive material of the above-described negative electrode active material layer is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10 wt% or less, preferably 5 wt% or less, based on the total weight of the negative electrode active material layer. The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber or metal fiber; fluorinated carbon; metal powder such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0175] The above negative electrode can be manufactured by applying and drying a composition for forming a negative electrode active material layer prepared by dissolving or dispersing a negative electrode active material, and optionally a binder and a conductive material in a solvent, on a negative electrode current collector, or by casting the composition for forming a negative electrode active material layer on a separate support, and then laminating the film obtained by peeling it off from the support on a negative electrode current collector.

[0176] The above separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without any particular restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture absorption capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may also be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0177] 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. As a specific example, the electrolyte may include an organic solvent and a lithium salt.

[0178] As the organic solvent, any solvent that can serve as a medium through which ions involved in the electrochemical reaction of the battery can move may be used without particular limitation. Specifically, the organic solvent includes 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; carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylenecarbonate (EC), and propylene carbonate (PC); Alcohol solvents such as ethyl alcohol, isopropyl alcohol, etc.; nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes, etc. can be used. Among these, carbonate solvents are preferable, 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 / discharge performance of a battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferable.

[0179] The above lithium salt can be used without any special limitation as long as it is a compound that can provide lithium ions used in a lithium secondary battery. Specifically, the anion of the above 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 - At least one selected from the group consisting of may be used, and the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. It is preferable to use the concentration of the lithium salt within the range of 0.1 M to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0180] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the lifespan of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 wt% to 5 wt% based on the total weight of the electrolyte.

[0181]

[0182] Since the lithium secondary battery including the positive electrode active material according to the present invention has excellent performance, it is useful in the fields of portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0183] There is no particular limitation on the external shape of the lithium secondary battery of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0184] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also be preferably used as a unit battery in a medium- to large-sized battery module including a plurality of battery cells.

[0185] Accordingly, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0186] The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0187]

[0188] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0189]

[0190] Examples and Comparative Examples

[0191] Example 1

[0192] A composite transition metal hydroxide (composition: Ni) in the form of secondary particles formed by the agglomeration of tens to hundreds of primary particles in an acoustic mixer 0.62 Co 0.06 Mn 0.32 (OH)2, D 50: 3.5㎛), ZrO2 (input in an amount such that Zr is 1500 ppm based on the total weight of the composite transition metal hydroxide) and Y2O3 (input in an amount such that Y is 3000 ppm based on the total weight of the composite transition metal hydroxide) were added and sequentially mixed at 40 g (g: gravitational acceleration) for 2 minutes, 80 g for 1 minute, and 50 g for 2 minutes. Afterwards, Li2CO3 was added to the acoustic mixer so that the ratio of the total mole number of transition metals included in the composite transition metal hydroxide (Ni+Co+Mn) to the mole number of lithium included in Li2CO3 (Li) ((Ni+Co+Mn):Li) was 1:1.05, and the mixture was prepared by sequentially mixing at 40 g (g: gravitational acceleration) for 2 minutes, 80 g for 1 minute, and 50 g for 2 minutes.

[0193] After the above mixture was placed in a square alumina crucible (150 mm × 150 mm), the first firing was performed at 850°C for 4 hours in an air atmosphere, the temperature was continuously increased to 965°C (heating rate: 1.3°C / min), the second firing was performed at 965°C for 6 hours, the temperature was continuously lowered to 600°C (heating rate: 4°C / min), and the third firing was performed at 600°C for 3 hours to manufacture a sintered product.

[0194] The above-mentioned product was pulverized using a jet mill (Isaac ENC Co., Ltd., 2-inch Air Jet Mill) at 4 bar for 10 minutes.

[0195] The above-mentioned pulverized product was mixed with Al2O3 (input in an amount such that Al is 1500 ppm based on the total weight of the sintered product) and WO3 (input in an amount such that W is 3000 ppm based on the total weight of the sintered product), and then heat-treated at 500°C in an air atmosphere to produce a cathode active material including a coating layer containing Al and W.

[0196]

[0197] Example 2

[0198] A composite transition metal hydroxide (composition: Ni) in the form of secondary particles formed by the agglomeration of tens to hundreds of primary particles in an acoustic mixer 0.62 Co 0.06 Mn 0.32 (OH)2, D 50 : 3.5㎛), ZrO2 (input in an amount such that Zr is 1500 ppm based on the total weight of the above-mentioned complex transition metal hydroxide) and Y2O3 (input in an amount such that Y is 3000 ppm based on the total weight of the above-mentioned complex transition metal hydroxide) were added and sequentially mixed at 40 g (g: gravitational acceleration) for 2 minutes, at 80 g for 1 minute, and at 50 g for 2 minutes. Afterwards, Li2CO3 was added to the acoustic mixer so that the ratio of the total mole number of transition metals included in the complex transition metal hydroxide (Ni+Co+Mn) to the mole number of lithium included in Li2CO3 (Li) ((Ni+Co+Mn):Li) was 1:1.04, and the mixture was prepared by sequentially mixing at 40 g (g: gravitational acceleration) for 2 minutes, at 80 g for 1 minute, and at 50 g for 2 minutes.

[0199] After the above mixture was placed in a square alumina crucible (150 mm × 150 mm), the first firing was performed at 850°C for 4 hours in an air atmosphere, the temperature was continuously increased to 965°C (heating rate: 1.3°C / min), the second firing was performed at 965°C for 6 hours, the temperature was continuously lowered to 600°C (heating rate: 4°C / min), and the third firing was performed at 600°C for 3 hours to manufacture a sintered product.

[0200] The above-mentioned product was pulverized using a jet mill (Isaac ENC Co., Ltd., 2-inch Air Jet Mill) at 4 bar for 10 minutes.

[0201] The above-mentioned pulverized product was mixed with Al2O3 (input in an amount such that Al is 1500 ppm based on the total weight of the sintered product) and WO3 (input in an amount such that W is 3000 ppm based on the total weight of the sintered product), and then heat-treated at 500°C in an air atmosphere to produce a cathode active material including a coating layer containing Al and W.

[0202]

[0203] Example 3

[0204] A composite transition metal hydroxide (composition: Ni) in the form of secondary particles formed by the agglomeration of tens to hundreds of primary particles in an acoustic mixer 0.62 Co 0.06 Mn 0.32 (OH)2, D 50 : 3.5㎛), ZrO2 (input in an amount such that Zr is 1500 ppm based on the total weight of the above-mentioned complex transition metal hydroxide) and Y2O3 (input in an amount such that Y is 3000 ppm based on the total weight of the above-mentioned complex transition metal hydroxide) were added and sequentially mixed at 40 g (g: gravitational acceleration) for 2 minutes, at 80 g for 1 minute, and at 50 g for 2 minutes. Thereafter, Li2CO3 was added to the acoustic mixer so that the ratio of the total mole number of transition metals included in the complex transition metal hydroxide (Ni+Co+Mn) to the mole number of lithium included in Li2CO3 (Li) ((Ni+Co+Mn):Li) was 1:1.06, and the mixture was prepared by sequentially mixing at 40 g (g: gravitational acceleration) for 2 minutes, at 80 g for 1 minute, and at 50 g for 2 minutes.

[0205] After the above mixture was placed in a square alumina crucible (150 mm × 150 mm), the first firing was performed at 850°C for 4 hours in an air atmosphere, the temperature was continuously increased to 965°C (heating rate: 1.3°C / min), the second firing was performed at 965°C for 6 hours, the temperature was continuously lowered to 600°C (heating rate: 4°C / min), and the third firing was performed at 600°C for 3 hours to manufacture a sintered product.

[0206] The above-mentioned product was pulverized using a jet mill (Isaac ENC Co., Ltd., 2-inch Air Jet Mill) at 4 bar for 10 minutes.

[0207] The above-mentioned pulverized product was mixed with Al2O3 (input in an amount such that Al is 1500 ppm based on the total weight of the sintered product) and WO3 (input in an amount such that W is 3000 ppm based on the total weight of the sintered product), and then heat-treated at 500°C in an air atmosphere to produce a cathode active material including a coating layer containing Al and W.

[0208]

[0209] Comparative Example 1

[0210] A composite transition metal hydroxide (composition: Ni) in the form of secondary particles formed by the agglomeration of tens to hundreds of primary particles in an acoustic mixer 0.62 Co 0.06 Mn 0.32 (OH)2, D 50: 3.5㎛), ZrO2 (input in an amount such that Zr is 1500 ppm based on the total weight of the composite transition metal hydroxide) and Y2O3 (input in an amount such that Y is 3000 ppm based on the total weight of the composite transition metal hydroxide) were added and sequentially mixed at 40 g (g: gravitational acceleration) for 2 minutes, 80 g for 1 minute, and 50 g for 2 minutes. Afterwards, Li2CO3 was added to the acoustic mixer so that the ratio of the total mole number of transition metals included in the composite transition metal hydroxide (Ni+Co+Mn) to the mole number of lithium included in Li2CO3 (Li) ((Ni+Co+Mn):Li) was 1:1.05, and the mixture was prepared by sequentially mixing at 40 g (g: gravitational acceleration) for 2 minutes, 80 g for 1 minute, and 50 g for 2 minutes.

[0211] After the above mixture was placed in a square alumina crucible (150 mm × 150 mm), the first firing was performed at 850°C for 4 hours in an air atmosphere, the temperature was continuously increased to 955°C (heating rate: 1.3°C / min), the second firing was performed at 955°C for 6 hours, the temperature was continuously lowered to 600°C (heating rate: 4°C / min), and the third firing was performed at 600°C for 3 hours to manufacture a sintered product.

[0212] The above-mentioned product was pulverized using a jet mill (Isaac ENC Co., Ltd., 2-inch Air Jet Mill) at 4 bar for 10 minutes.

[0213] The above-mentioned pulverized product was mixed with Al2O3 (input in an amount such that Al is 1500 ppm based on the total weight of the sintered product) and WO3 (input in an amount such that W is 3000 ppm based on the total weight of the sintered product), and then heat-treated at 500°C in an air atmosphere to produce a cathode active material including a coating layer containing Al and W.

[0214]

[0215] Comparative Example 2

[0216] A composite transition metal hydroxide (composition: Ni) in the form of secondary particles formed by the agglomeration of tens to hundreds of primary particles in an acoustic mixer 0.62 Co 0.06 Mn 0.32 (OH)2, D 50 : 3.5㎛), ZrO2 (input in an amount such that Zr is 1500 ppm based on the total weight of the composite transition metal hydroxide) and Y2O3 (input in an amount such that Y is 3000 ppm based on the total weight of the composite transition metal hydroxide) were sequentially mixed at 40 g (g: gravitational acceleration) for 2 minutes, 80 g for 1 minute, and 50 g for 2 minutes. Thereafter, Li2CO3 was added to the acoustic mixer so that the ratio of the total mole number of transition metals included in the composite transition metal hydroxide (Ni+Co+Mn) to the mole number of lithium included in Li2CO3 (Li) ((Ni+Co+Mn):Li) was 1:1.05, and the mixture was prepared by sequentially mixing at 40 g (g: gravitational acceleration) for 2 minutes, 80 g for 1 minute, and 50 g for 2 minutes.

[0217] After the above mixture was placed in a square alumina crucible (150 mm × 150 mm), it was first fired at 850°C for 4 hours in an air atmosphere, then the temperature was continuously raised to 975°C (heating rate: 1.3°C / min), fired a second time at 975°C for 6 hours, then the temperature was continuously lowered to 600°C (heating rate: 4°C / min), fired a third time at 600°C for 3 hours, and a fired product was manufactured.

[0218] The above-mentioned product was pulverized using a jet mill (Isaac ENC Co., Ltd., 2-inch Air Jet Mill) at 4 bar for 10 minutes.

[0219] The above-mentioned pulverized product was mixed with Al2O3 (input in an amount such that Al is 1500 ppm based on the total weight of the sintered product) and WO3 (input in an amount such that W is 3000 ppm based on the total weight of the sintered product), and then heat-treated at 500°C in an air atmosphere to produce a cathode active material including a coating layer containing Al and W.

[0220]

[0221] Experimental example

[0222]

[0223] Experimental Example 1: Analysis of the shape of the positive electrode active material

[0224] Using SEM (FEI, Inspect F), SEM images of each of the positive electrode active materials manufactured in Examples 1 and 3 were obtained. The SEM image of the positive electrode active material of Example 1 is shown in Fig. 1, and the SEM image of the positive electrode active material of Example 3 is shown in Fig. 2.

[0225] Referring to FIGS. 1 and 3, it can be confirmed that the positive electrode active materials of Examples 1 and 3 are in the form of single particles.

[0226]

[0227] Experimental Example 2: ICP Analysis

[0228] Each of the sintered products (hereinafter referred to as lithium composite transition metal oxides) manufactured in the Examples and Comparative Examples was taken in an amount of 0.1 g, 1 ml of hydrochloric acid was added, and heating was performed to dissolve the lithium composite transition metal oxide. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction, completely dissolving the lithium composite transition metal oxide to prepare a solution. Subsequently, the solution was diluted with deionized water to a total volume of 10 ml to prepare an analysis sample. Using an ICP device (ICP-OES; Agilent 5110, Agilent Technologies Co., Ltd.), the weight ratio of the constituent elements present in the analysis sample was measured, and the composition of the lithium composite transition metal oxide, the content of Zr (ppm) and the content of Y (ppm) present in the lithium composite transition metal oxide are shown in Table 1 below.

[0229] Lithium complex transition metal oxide composition Zr content (ppm) Y content (ppm) Example 1 Li[Ni 0.62 Co 0.06 Mn 0.32 ] 0.997 Zr 0.0015 Y 0.0015 O214842988 Example 2Li[Ni 0.62 Co 0.06 Mn 0.32 ] 0.997 Zr 0.0015 Y 0.0015 O214712998 Example 3Li[Ni 0.62 Co 0.06 Mn 0.32 ] 0.997 Zr 0.0015 Y 0.0015 O214872986Comparative Example 1Li[Ni 0.62 Co 0.06 Mn 0.32 ] 0.997 Zr 0.0015 Y 0.0015 O214822989Comparative Example 2Li[Ni 0.62 Co 0.06 Mn 0.32 ] 0.997 Zr 0.0015 Y 0.0015 O214762992

[0230] Through the above Table 1, it was confirmed that the lithium composite transition metal oxides manufactured in Examples 1 to 3 have a composition represented by Chemical Formula 1 described herein and include doping elements Zr and Y.

[0231]

[0232] Experimental Example 3: Particle Size Analysis of Positive Electrode Active Material (1)

[0233] Using SEM (FEI, Inspect F), SEM images of each positive electrode active material manufactured in the examples and comparative examples were obtained, and using an image processing program (LG Chemical, DX program), the boundaries of the primary particles existing in the SEM images were divided to obtain images represented in random colors.

[0234] Using an image in which the boundaries of the above primary particles are divided and displayed in random colors, the area of ​​each primary particle is calculated through the number of pixels corresponding to each of n primary particles (an average of 50,000 or more primary particles), and the radius (r) of a circle having the same area as the area of ​​each of the above primary particles i ) to determine the particle diameter (D) of each primary particle present in the SEM image. i =2r i ) is obtained, and the areas of the particles with a diameter of 1㎛ or less among the primary particles are added to obtain the sum of the areas of the primary particles with a diameter of 1㎛ or less, and the areas of all the primary particles are added to obtain the sum of the areas of all the primary particles, and then the small particle ratio is obtained according to Equation 1 described in this specification, and this is shown in Table 2 below.

[0235] In addition, by using an image in which the boundaries of the primary particles are divided and displayed in random colors, the area of ​​each primary particle is calculated through the number of pixels corresponding to each of n primary particles (an average of 50,000 or more primary particles), and the radius (r) of a circle having the same area as the area of ​​each primary particle is calculated. i) to determine the particle diameter (D) of each primary particle present in the SEM image. i =2r i ) and volume (V i =4 / 3×πr i 3 ) is calculated, and the particle diameter at the point where the volume cumulative distribution according to particle size is 50% is calculated to obtain the D of the primary particle. v,50 The values ​​were obtained and are shown in Table 2 below.

[0236]

[0237] Experimental Example 4: Particle Size Analysis of Positive Electrode Active Material (2)

[0238] After taking 0.01 g of each positive electrode active material (powder) manufactured in the examples and comparative examples, put it in a vial containing 30 ml of ultrapure water and 500 μl of dispersant, disperse the positive electrode active material with a sonicator for 1 minute, and then put it in a PSA (Microtrac, S3500) and analyze it, D 50 , and this is shown in Table 2 below.

[0239] At this time, D 50 refers to the particle size at the 50% point of the cumulative volume distribution according to particle size.

[0240]

[0241] Experimental Example 5: Evaluation of Differential Generation Amount

[0242] Each of the positive electrode active materials (powder) manufactured in the examples and comparative examples was taken in an amount of 3 g, placed in a mold with an inner diameter of 13 mm, and pressurized at 9 tons for 1 minute. The number of particles with a particle diameter of less than 1 μm was confirmed using PSA (Microtrac, S3500). Then, the ratio of the number of particles with a particle diameter of less than 1 μm to the total number of particles (hereinafter referred to as the amount of fine particles generated) was calculated and shown in Table 2 below.

[0243]

[0244] Experimental Example 6: Rolling Density Measurement

[0245] Each of the positive electrode active materials (powder) manufactured in the examples and comparative examples was taken in an amount of 5 g, placed in a mold with an inner diameter of 20 mm, and pressurized at 2 tons for 1 minute. The height of the mold after pressurization was measured. From the height, the volume after applying pressure to 5 g of the positive electrode active material was calculated, and the weight of the active material per unit volume after pressurization, i.e., the rolling density, was obtained and is shown in Table 2 below.

[0246]

[0247] Primary particle ratio (%) D of primary particles v,50 D measured by (㎛)PSA 50 (㎛) Fine powder generation amount (%) Rolling density (g / cm) 3 )Example 17.42.73.50.42.81Example 26.52.53.60.62.74Example 38.02.93.80.42.84Comparative Example 114.62.13.62.92.67Comparative Example 22.53.83.90.12.89

[0248] Referring to Table 2 above, the positive electrode active materials of Examples 1 to 3 satisfy the small particle ratio range of 5% to 10%, and the D of the primary particles v,50 While satisfying this 2.2㎛ to 3.7㎛, the positive electrode active material of comparative example 1 has a high particle ratio of more than 10%, and the D of the primary particles v,50 It can be confirmed that this is less than 2.2㎛. In addition, the positive electrode active material of comparative example 2 has a low particle ratio of less than 5%, and the D of the primary particle v,50 It can be confirmed that this exceeds 3.7㎛.

[0249] Typically, lower fine particle generation reduces the specific surface area between particles and electrolyte, which can suppress side reactions and improve capacity retention and gas generation during charge / discharge cycles. Meanwhile, higher rolling density is advantageous because it allows for a greater amount of active material to be coated per unit volume during electrode fabrication. However, fine particle generation and rolling density are in conflict with each other, so finding the optimal conditions requires a comprehensive evaluation of other performance factors.

[0250]

[0251] Experimental Example 7: Battery Performance Evaluation

[0252] The positive electrode slurry was prepared by mixing the positive electrode active materials manufactured in the examples and comparative examples, the FX35 conductive agent, and the polyvinylidene fluoride (PVDF) binder in a ratio of 95:3:2 in an N-methylpyrrolidone (NMP) solvent. The positive electrode slurry was applied to one surface of an aluminum current collector, dried at 130°C for 10 minutes or more, and rolled to prepare a positive electrode.

[0253] A lithium metal electrode was used as the negative electrode, and a porous polyethylene separator was interposed between the positive and negative electrodes to manufacture an electrode assembly. The electrode assembly was then placed inside a battery case, and an electrolyte was injected into the case to manufacture a half-cell. At this time, the electrolyte was prepared by dissolving 1.0 M LiPF6 in an organic solvent containing ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) in a volume ratio of 3:4:3.

[0254] For each half cell manufactured in this way, the initial charge capacity and initial discharge capacity were measured while charging at 0.1C in CC-CV mode at 25℃ to 4.5V and discharging at a constant current of 0.1C to 2.5V, and the initial charge / discharge capacity, initial efficiency, and direct current internal resistance (DCIR) were calculated, which are shown in Table 3 below. For reference, the initial efficiency value is the percentage value of the initial discharge capacity to the initial charge capacity, and the DCIR value is the value calculated by dividing the difference between the voltage at 60 seconds and the initial voltage while discharging at a constant current of 0.1C by the applied current.

[0255] ClassificationInitial charge capacity (mAh / g)Initial discharge capacity (mAh / g)Initial efficiency (%)DCIR (Ω)Example 1223.0202.090.633.6Example 2222.3200.990.432.1Example 3223.6202.990.832.5Comparative example 1222.5202.090.829.6Comparative example 2222.3197.788.939.5

[0256] Referring to Table 2 and Table 3 above, the positive electrode active materials of Examples 1 to 3 have a small particle ratio in the range of 5% to 10%, and the D of the primary particles v,50 By satisfying this 2.2㎛ to 3.7㎛ range, it can be confirmed that in the case of a battery including it, the capacity, initial efficiency, and resistance performance of the battery are all superior to the batteries including the positive electrode active materials of Comparative Examples 1 and 2.

Claims

1. A lithium composite transition metal oxide having a composition represented by the following chemical formula 1 and having a single particle form composed of 10 or fewer primary particles, The above primary particles are D derived from SEM images v,50 This is 2.2㎛ to 3.7㎛, A cathode active material having a particle ratio of 5% to 10% according to the following formula 1: [Chemical Formula 1] Li 1+x Ni a1 Co b1 Mr c1 Zr d1 Y e1 M f1 O 2-y A y In the above chemical formula 1, M is at least one selected from W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si, and Al, A is at least one selected from F, Cl, Br, I, and S, -0.1≤x≤0.1, 0 <a1<1, 0<b1<1, 0<c1<1, 0<d1<0.01, 0<e1<0.01, 0≤f1<0.1, 0≤y≤0.2, a1+b1+c1+d1+e1+f1=1이고, [Formula 1] Small particle ratio (%) = (sum of the area of ​​primary particles with a particle size of 1 μm or less derived from SEM images / sum of the area of ​​all primary particles derived from SEM images) × 100.

2. In claim 1, The above primary particles are D derived from SEM images v,50 This positive electrode active material having a diameter of 2.5㎛ to 2.8㎛.

3. In claim 1, The above positive electrode active material has a D measured by PSA (particle size analyzer) 50 This positive electrode active material is 3.5㎛ to 4㎛.

4. In claim 1, The above lithium composite transition metal oxide is a cathode active material doped with 1000 ppm to 4000 ppm of Zr and 1000 ppm to 4000 ppm of Y.

5. In claim 1, The above positive electrode active material further includes a coating layer formed on the lithium composite transition metal oxide, The above coating layer is a positive electrode active material comprising Al, W or a combination thereof.

6. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 5.

7. The anode according to claim 6; cathode; a separator interposed between the anode and the cathode; and A lithium secondary battery comprising an electrolyte.

Images