Cathode active material, method for manufacturing same, and cathode and lithium secondary battery comprising same

Abstract

The present invention relates to a cathode active material that has a uniform particle diameter, and thus can improve capacity, initial efficiency, lifespan, and resistance performance of a battery, and to: a cathode active material; a method for manufacturing same; and a cathode and a lithium secondary battery, comprising same, the cathode active material including a lithium nickel cobalt manganese-based oxide in the form of a single-particle doped with Zr and Y, and having a polydispersity index (PDI) value of 1.0 to 2.0 according to equation 1 described in the present specification.

Description

Positive electrode active material, method for producing the same, and positive electrode and lithium secondary battery including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0151124, filed November 3, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a positive electrode active material, a method for producing the same, and a positive electrode and a lithium secondary battery comprising the same, and more particularly, to a positive electrode active material having a uniform particle size, a method for producing the same, and a positive electrode and a lithium secondary battery comprising the same.

[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] Meanwhile, additives used to improve the high-voltage charge-discharge efficiency and lifespan of single-particle cathode active materials are typically metal oxides in powder form (dry doping). However, dry doping can compromise particle growth uniformity due to the uneven influence of the additives.

[0010] Therefore, there is a need to develop a positive electrode active material in the form of a single particle with a uniform particle size.

[0011]

[0012] The present invention is an invention for solving the above problems, and aims to provide a single particle type positive electrode active material that has a uniform particle size and can improve the performance of a battery.

[0013] In addition, the present invention aims to provide a manufacturing method for manufacturing the positive electrode active material.

[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 cathode active material, a method for manufacturing a cathode active material, a cathode, and a lithium secondary battery.

[0017] (1) The present invention provides a cathode active material comprising a lithium nickel cobalt manganese oxide in the form of a single particle having a nickel content of 60 mol% or more among the total transition metal and consisting of 10 or fewer primary particles, wherein the lithium nickel cobalt manganese oxide is doped with zirconium (Zr) and yttrium (Y), and has a polydispersity index (PDI) value of 1.0 to 2.0 according to the following formula 1.

[0018] [Formula 1]

[0019] PDI = .

[0020] (2) The present invention provides a positive electrode active material in the above (1), wherein the lithium nickel cobalt manganese oxide has a composition represented by the following chemical formula 1.

[0021] [Chemical Formula 1]

[0022] Li 1+x Ni a1 Co b1 Mn c1 Zr d1 Y e1 M f1 O2

[0023] In the above chemical formula 1,

[0024] M is at least one selected from W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si, and Al,

[0025] -0.1≤x≤0.1, 0.6≤a1<1, 0 <b1<0.4, 0<c1<0.4, 0<d1≤0.01, 0<e1≤0.01, 0≤f1≤0.1, a1+b1+c1+d1+e1+f1=1이다.

[0026] (3) The present invention provides a positive electrode active material in the above (1) or (2), wherein the lithium nickel cobalt manganese oxide is doped with 1,500 ppm to 4,500 ppm of Zr and 1,500 ppm to 4,500 ppm of Y.

[0027] (4) The present invention provides a positive electrode active material in any one of the above (1) to (3), wherein the volume average particle diameter of the primary particles is 2.4 µm to 3.0 µm.

[0028] (5) The present invention provides a positive electrode active material in any one of the above (1) to (4), wherein the number average particle diameter of the primary particles is 1.2 µm to 3.0 µm.

[0029] (6) In any one of the above (1) to (5), 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 4.1㎛.

[0030] (7) The present invention relates to a method for manufacturing ... v,90 -D v,10 ) / D v,50 ) provides a positive electrode active material having a value of 0.9 or less.

[0031] (8) The present invention is one of the above (1) to (7), wherein the D of the primary particle v,50 Provides a positive electrode active material having a diameter of 2.2㎛ to 3.2㎛.

[0032] (9) In any one of the above (1) to (8), the positive electrode active material further includes a coating layer formed on the lithium nickel cobalt manganese oxide,

[0033] The above coating layer provides a positive electrode active material comprising Al, W or a combination thereof.

[0034] (10) The present invention provides a positive electrode active material in which the content of Al included in the coating layer is 1,000 ppm to 2,000 ppm relative to the total weight of the positive electrode active material in (9).

[0035] (11) The present invention provides a positive electrode active material in (9) or (10) above, wherein the content of W included in the coating layer is 2,000 ppm to 4,000 ppm relative to the total weight of the positive electrode active material.

[0036] (12) The present invention provides a method for producing a positive electrode active material, comprising: (A) a step of mixing a composite transition metal hydroxide having a composition represented by the following chemical formula 2, an yttrium-containing raw material, and a lithium-containing raw material to produce a mixture; and (B) a step of sequentially firing the mixture at 750°C to 900°C for the first time, at 920°C to 1,000°C for the second time, and at 500°C to 800°C for the third time in an air atmosphere to produce a fired product.

[0037] [Chemical Formula 2]

[0038] Ni a2 Co b2 Mn c2 Zr d2 M' e2 (OH)2

[0039] In the above chemical formula 2,

[0040] M' is at least one selected from W, Cu, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al,

[0041] 0.6≤a2<1, 0 <b2<0.4, 0<c2<0.4, 0<d2≤0.01, 0≤e2≤0.1, a2+b2+c2+d2+e2=1이다.

[0042] (13) The present invention provides a method for manufacturing a positive electrode active material, wherein, in the above (12), the first firing is performed for 2 to 10 hours.

[0043] (14) The present invention provides a method for manufacturing a positive electrode active material, wherein in the above (12) or (13), the secondary firing is performed for 2 to 10 hours.

[0044] (15) The present invention provides a method for manufacturing a positive electrode active material, wherein the third firing is performed for 2 to 10 hours in any one of the above (12) to (14).

[0045] (16) The present invention provides a method for manufacturing a positive electrode active material, further comprising the step of (C) pulverizing the sintered product in any one of (12) to (15).

[0046] (17) The present invention provides a method for producing a positive electrode active material, wherein the fine grinding is performed by air-flow grinding in the above (16).

[0047] (18) The present invention provides a method for producing a positive electrode active material, wherein the airflow grinding in (17) is performed under a pressure of 2.5 bar to 4 bar.

[0048] (19) The present invention provides a method for manufacturing a positive electrode active material, further comprising 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 any one of the above (12) to (18).

[0049] (20) The present invention provides a positive electrode comprising a positive electrode active material according to any one of (1) to (11).

[0050] (21) The present invention provides a lithium secondary battery comprising a positive electrode according to (20); a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte.

[0051]

[0052] The cathode active material of the present invention comprises a lithium nickel cobalt manganese oxide (lithium composite transition metal oxide) in the form of a single particle doped with Zr and Y, and has a polydispersity index value according to Equation 1 described herein that satisfies a specific range, thereby improving cathode active material particle breakage during rolling for manufacturing a lithium secondary battery, and improving the capacity, initial efficiency, lifespan, and resistance performance of the lithium secondary battery.

[0053] In addition, according to the method for manufacturing a positive electrode active material of the present invention, the positive electrode active material described above can be effectively manufactured.

[0054] The cathode and lithium secondary battery according to the present invention can have excellent capacity, initial efficiency, lifespan, and resistance performance.

[0055]

[0056] Figure 1 is an SEM image (5,000×) of each positive electrode active material manufactured in Examples 1 and 2 and Comparative Examples 1 and 2.

[0057] Figure 2 is a drawing showing the SEM images (5,000×) of each of the positive electrode active materials manufactured in Examples 1 and 2 and Comparative Examples 1 and 2, processed to show the boundaries of the primary particles divided and displayed in random colors.

[0058]

[0059] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0060] 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.

[0061]

[0062] 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.

[0063] 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.

[0064] 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.

[0065] '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.

[0066] In this specification, the 'volume average particle diameter of primary particles' is a value according to the following Equation 2, and the area of ​​each primary particle is calculated through the number of pixels corresponding to each of n primary particles existing in the SEM image, and the radius (r) of a circle having the same area as the area of ​​each primary particle 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 product of the calculated volume and particle diameter for each primary particle is calculated (V i D i ) is the total volume (V) calculated i ) is the value derived by dividing by the total sum of all values.

[0067] [Formula 2]

[0068]

[0069] In the above equation 2,

[0070] n is the number of primary particles present in the SEM image,

[0071] V i is the volume of one primary particle among n primary particles,

[0072] V i D i is the volume of one primary particle among n primary particles (V i ) and entrance diameter (D i ) is the product of

[0073] In this specification, the 'average number diameter of primary particles' is a value according to the following Equation 3, and the area of ​​the primary particles is calculated through the number of pixels corresponding to each of n primary particles existing in the SEM image, and the radius (r) of a circle having the same area as the area of ​​each of the primary particles i ) to determine the particle diameter (D) of each primary particle present in the SEM image. i =2r i ) is calculated and the total sum of the calculated particle sizes is divided by the number of primary particles.

[0074] [Formula 3]

[0075]

[0076] In the above equation 3,

[0077] n is the number of primary particles present in the SEM image,

[0078] D i is the particle diameter (D) of one primary particle among n primary particles.i )am.

[0079] 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.

[0080] In this specification, the primary particle 'D v,10 , D v,50 , D v,90 ' is calculated by calculating the area of ​​each primary particle through the number of pixels corresponding to each of n primary particles existing in the SEM image, calculating the particle diameter and volume of each primary particle existing in the SEM image using the radius value of a circle having the same area as the area of ​​each primary particle, and calculating the particle diameter at points that are 10%, 50%, and 90% of the cumulative volume distribution according to particle diameter. In addition, the span value of the primary particle is obtained by calculating the 'D v,10 , D v,50 , D v,90 ' (D v,90 -D v,10 ) / D v,50 This is the value obtained by substituting it into .

[0081]

[0082] positive electrode active material

[0083] The present invention provides a cathode active material comprising a lithium nickel cobalt manganese oxide having a nickel content of 60 mol% or more among the total transition metal and a single particle form composed of 10 or fewer primary particles, wherein the lithium nickel cobalt manganese oxide is doped with zirconium (Zr) and yttrium (Y), and has a polydispersity index (PDI) value of 1 to 2.0 according to the following formula 1. The lithium nickel cobalt manganese oxide may have a layered structure.

[0084] [Formula 1]

[0085] PDI = .

[0086]

[0087] The present inventors have found that when a cathode active material includes a lithium nickel cobalt manganese oxide in the form of a single particle doped with Zr and Y and a polydispersity index (PDI) value according to the above formula 1 satisfies a specific range, the cathode active material particles are less likely to break during rolling for manufacturing a lithium secondary battery, thereby improving the capacity, initial efficiency, lifespan, and resistance performance of the lithium secondary battery, thereby completing the present invention.

[0088]

[0089] According to the present invention, the lithium nickel cobalt manganese oxide may have a nickel content of 60 mol% or more among the total transition metals. Specifically, the lithium nickel cobalt manganese oxide may contain nickel in an amount of 60 mol% or more, or 61 mol% or more, based on the total moles of metals excluding lithium. That is, the lithium nickel cobalt manganese 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.

[0090] According to the present invention, the lithium nickel cobalt manganese oxide is doped with Zr and Y. In this case, the particle shape is improved and the structure is stabilized, thereby realizing high capacity characteristics and high energy density per unit volume.

[0091] Meanwhile, if the lithium nickel cobalt manganese oxide is not doped with Zr, the structural stability is relatively low during insertion and de-insertion of lithium, which may cause problems in the life performance of the lithium secondary battery. In addition, if it is not doped with Y, firing at a higher temperature is required for particle growth, which results in an increase in the resistance of the positive electrode active material produced.

[0092] According to the present invention, the positive electrode active material has a polydispersity index (PDI) value of 1.0 to 2.0 according to Equation 1. Theoretically, when all primary particles forming the lithium nickel cobalt manganese oxide have the same particle size, the polydispersity index (PDI) value is 1.0, and the more uniform the particle size, the closer the PDI value is to 1.0. Specifically, the polydispersity index value may be 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, or 1.8 or more, and may be 1.9 or less, or 2.0 or less. When the polydispersity index value satisfies the above range, it can be seen that the primary particles have grown very uniformly, and thus local degradation of the positive electrode active material is prevented, thereby improving the performance (capacity, initial efficiency, lifespan, resistance performance, etc.) of the battery. The above polydispersity index value is determined by a complex interaction of factors such as the manufacturing method of the positive electrode active material, composition, type of doping element, size of primary particles, and particle size distribution, and is not determined by any one factor alone.

[0093] Meanwhile, when the polydispersity index of the positive electrode active material exceeds 2.0, the primary particle size is not uniform, so the positive electrode active material particles are more likely to break during rolling for manufacturing a lithium secondary battery, which causes a problem in that the resistance and life performance of the lithium secondary battery are reduced.

[0094]

[0095] According to the present invention, the lithium nickel cobalt manganese oxide may have a composition represented by the following chemical formula 1.

[0096] [Chemical Formula 1]

[0097] Li 1+x Ni a1 Co b1 Mn c1 Zr d1 Y e1 M f1 O2

[0098] In the above chemical formula 1,

[0099] M is at least one selected from W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si, and Al,

[0100] -0.1≤x≤0.1, 0.6≤a1<1, 0 <b1<0.4, 0<c1<0.4, 0<d1≤0.01, 0<e1≤0.01, 0≤f1≤0.1, a1+b1+c1+d1+e1+f1=1이다.

[0101] The above 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, 0 or more, 0.01 or more, 0.02 or more, 0.03 or more, or 0.04 or more, and may be 0.05 or less, 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.

[0102] According to the present invention, in the chemical formula 1, a1 means the atomic fraction of nickel among the metal elements in the lithium nickel cobalt manganese oxide, and may be 0.6 or more, or 0.61 or more, and may be 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.

[0103] According to the present invention, in the chemical formula 1, the b1 refers to the atomic fraction of cobalt among the metal elements in the lithium nickel cobalt manganese 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, 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 b1 satisfies the above range, stability can be improved and rate characteristics can be enhanced during the charge and discharge process.

[0104] According to the present invention, in the chemical formula 1, c1 means the atomic fraction of manganese among the metal elements in the lithium nickel cobalt manganese 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.

[0105] 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 nickel cobalt manganese oxide, and may be 0 or more, 0.001 or more, 0.002 or more, or 0.003 or more, and may be 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.

[0106] 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 nickel cobalt manganese 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.

[0107] 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 nickel cobalt manganese 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.

[0108]

[0109] According to the present invention, the lithium nickel cobalt manganese oxide may be doped with 1,500 ppm to 4,500 ppm of Zr and 1,500 ppm to 45,00 ppm of Y.

[0110] The content of Zr may be specifically 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, 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, It may be 3,700 ppm or less, 3,800 ppm or less, 3,900 ppm or less, 4,000 ppm or less, 4,100 ppm or less, 4,200 ppm or less, 4,300 ppm or less, 4,400 ppm or less, or 4,500 ppm or less.

[0111] The content of Y may be specifically 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, or 2,400 ppm or more, based on the total weight of the lithium nickel cobalt manganese oxide, and may be 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, 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, It may be 3,800 ppm or less, 3,900 ppm or less, 4,000 ppm or less, 4,100 ppm or less, 4,200 ppm or less, 4,300 ppm or less, 4,400 ppm or less, or 4,500 ppm or less.

[0112] When the content of Y is within the above range, the growth of particles is promoted due to the influence of Y, so that the grain size and the size of primary particles increase, and thus the capacity and life performance of the battery can be improved. When the content of Zr is within the above range, Zr is stably doped into the transition metal layer, so that the structural stability is improved during insertion and de-insertion of lithium, and as a result, the particle strength is excellent, and thus the life and resistance performance of the battery can be improved.

[0113]

[0114] According to the present invention, the volume average particle diameter of the primary particles may be 2.4 µm to 3.0 µm. Specifically, the volume average particle diameter of the primary particles may be 2.4 µm or more, or 2.5 µm or more, and may be 2.7 µm or less, 2.8 µm or less, 2.9 µm or less, or 3.0 µm or less. When the volume average particle diameter of the primary particles is within the above range, lithium movement is advantageous, so that the charge / discharge capacity and efficiency of the battery are improved, and the life performance can be improved.

[0115]

[0116] According to the present invention, the number average particle diameter of the primary particles may be 1.2 µm to 3.0 µm. Specifically, the number average particle diameter of the primary particles may be 1.2 µm or more, or 1.3 µm or more, and may be 1.5 µm or less, 1.6 µm or less, 1.7 µm or less, 1.8 µm or less, 1.9 µm or less, 2.0 µm or less, 2.1 µm or less, 2.2 µm or less, 2.3 µm or less, 2.4 µm or less, 2.5 µm or less, 2.6 µm or less, 2.7 µm or less, 2.8 µm or less, 2.9 µm or less, or 3.0 µm or less. When the number average particle diameter of the primary particles is within the above range, the ratio of small particles (primary particles having a particle diameter of less than 1 µm) that participate in the life performance decreases, so the life performance can be improved.

[0117]

[0118] 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 4.1㎛. The average particle diameter (D) of the positive electrode active material 50) Specifically, it may be 3.50㎛ or more, 3.60㎛ or more, 3.70㎛ or more, or 3.80㎛ or more, and 3.90㎛ or less, 4.00㎛ or less, or 4.10㎛ 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 4.1㎛, the battery capacity may be reduced.

[0119]

[0120] According to the present invention, the span ((D) of the primary particle v,90 -D v,10 ) / D v,50 ) may be 0.9 or less. The span value of the primary particles may be specifically 0 or more, 0.10 or more, 0.20 or more, 0.30 or more, 0.40 or more, 0.50 or more, 0.60 or more, 0.70 or more, or 0.80 or more, and may be 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, or 0.90 or less. When the span value of the primary particles is within the above range, it can be determined that the distribution of particle sizes is uniform, and the life performance can be improved by uniform particle growth.

[0121]

[0122] According to the present invention, D of the primary particle v,50 The D of the primary particles may be 2.2 μm to 3.2 μm. v,50Specifically, it may be 2.20㎛ or more, 2.25㎛ or more, 2.30㎛ or more, 2.35㎛ or more, 2.40㎛ or more, 2.45㎛ or more, 2.50㎛ or more, or 2.55㎛ or more, and may be 2.70㎛ or less, 2.75㎛ or less, 2.80㎛ or less, 2.85㎛ or less, 2.90㎛ or less, 2.95㎛ or less, 3.00㎛ or less, 3.05㎛ or less, 3.10㎛ or less, 3.15㎛ or less, or 3.20㎛ or less. D of the primary particle v,50 Within this range, lithium movement is advantageous, so that charge / discharge capacity and efficiency are improved, and life performance can be improved.

[0123]

[0124] According to the present invention, the positive electrode active material further includes a coating layer formed on the lithium nickel cobalt manganese oxide, and the coating layer may include Al, W, or a combination thereof. In this case, the electrical conductivity of the positive electrode active material is improved, and side reactions with the electrolyte in the battery are suppressed, so that the capacity characteristics, resistance characteristics, and life characteristics of the battery can be improved. Specifically, the production of byproducts in the form of hydrogen fluoride, which may be generated by side reactions with the electrolyte in the battery, is suppressed, so that high-capacity characteristics can be exhibited at a high rate.

[0125]

[0126] 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, or 1,300 ppm or more, and 1,400 ppm or less, 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.

[0127] 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, or 2,200 ppm or more, and 2,500 ppm or less, 2,600 ppm or less, 2,700 ppm or less, 2,800 ppm or less, 2,900 ppm or less, 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 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 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.

[0128]

[0129] Method for manufacturing positive electrode active material

[0130] The present invention provides a method for producing the above-described positive electrode active material. That is, the positive electrode active material according to the present invention is produced by the following method for producing a positive electrode active material.

[0131] A method for producing a single-particle type positive electrode active material according to the present invention comprises the steps of (A) mixing a composite transition metal hydroxide having a composition represented by the following chemical formula 2, an 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 750°C to 900°C for the first time, at 920°C to 1,000°C for the second time, and at 500°C to 800°C for the third time to produce a fired product.

[0132] [Chemical Formula 2]

[0133] Ni a2 Co b2 Mn c2 Zr d2 M' e2 (OH)2

[0134] In the above chemical formula 2,

[0135] M' is at least one selected from W, Cu, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al,

[0136] 0.6≤a2<1, 0 <b2<0.4, 0<c2<0.4, 0<d2≤0.01, 0≤e2≤0.1, a2+b2+c2+d2+e2=1이다.

[0137]

[0138] The present inventors have found that when a mixture of a yttrium-containing raw material and a lithium-containing raw material is sequentially fired at 750°C to 900°C for the first time, at 920°C to 1,000°C for the second time, and then at 500°C to 800°C for the third time, a positive electrode active material in the form of single particles having a uniform primary particle size is produced, thereby reducing breakage of the positive electrode active material particles during rolling for the manufacture of a lithium secondary battery, thereby completing the present invention.

[0139]

[0140] (A) Step

[0141] The above step (A) is a step of preparing a mixture by mixing a composite transition metal hydroxide having a composition represented by the above chemical formula 2, an yttrium-containing raw material, and a lithium-containing raw material.

[0142] 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, or 0.61 or more, and may be 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 high voltage, thereby realizing a high-capacity characteristic.

[0143] 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.

[0144] 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.

[0145] According to the present invention, in the chemical formula 2, d2 refers to the atomic fraction of zirconium among the metal elements in the composite transition metal hydroxide, and may be 0 or more, 0.001 or more, 0.002 or more, or 0.003 or more, and may be 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 d2 satisfies the above range, the crystal structure stability of the resulting positive electrode active material is improved, and the resistance and lifespan of the battery can be improved due to the increased structural stability.

[0146] According to the present invention, in the chemical formula 2, e2 means the atomic fraction of the M' element among the metal elements in the composite transition metal hydroxide, 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 e2 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.

[0147]

[0148] The above complex transition metal hydroxide can be produced by a co-precipitation reaction of a complex transition metal-containing solution including Ni, Co, Mn, and Zr, a basic aqueous solution, and an ammonium cation complex forming agent. Specifically, a reaction solution including a complex transition metal-containing solution, a basic aqueous solution, and an ammonium cation complex forming agent is introduced into a reactor, and a co-precipitation reaction is performed, thereby producing a complex transition metal hydroxide, which is a positive electrode active material precursor.

[0149] The above-mentioned complex transition metal-containing solution contains cations of Ni, Co, Mn, and Zr metals. The above-mentioned complex transition metal-containing solution may contain acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide of the above-mentioned metals, and is not particularly limited as long as it can be dissolved in water.

[0150] The above basic aqueous solution may include at least one selected from an alkali metal hydrate, an alkali metal hydroxide, an alkaline earth metal hydrate, and an alkaline earth metal hydroxide. For example, the above basic aqueous solution may include NaOH, KOH, Ca(OH)2, etc., and as a solvent, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) that can be uniformly mixed with water may be used.

[0151] The above ammonium cation complex forming agent may include at least one selected from NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3. As the solvent, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) that can be uniformly mixed with water may be used.

[0152] The above coprecipitation reaction may be performed for 1 hour to 50 hours. Specifically, the coprecipitation reaction may be performed for 1 hour or more, 5 hours or more, 10 hours or more, 11 hours or more, 12 hours or more, 13 hours or more, 14 hours or more, 15 hours or more, 16 hours or more, 17 hours or more, 18 hours or more, 19 hours or more, or 20 hours or more, and 30 hours or less, 31 hours or less, 32 hours or less, 33 hours or less, 34 hours or less, 35 hours or less, 36 hours or less, 37 hours or less, 38 hours or less, 39 hours or less, 40 hours or less, 45 hours or less, or 50 hours or less. When the coprecipitation reaction is performed for a time within the above range, the crystallinity of the composite transition metal hydroxide particles can be sufficiently controlled.

[0153] At this time, the basic aqueous solution may be added in an amount such that the pH of the reaction solution becomes a desired range. The coprecipitation reaction may be performed at a pH of 10 to 13 or lower. Specifically, it may be performed at a pH of 10 or higher, pH 10.5 or higher, pH 11 or higher, or pH 11.5 or higher, and pH 12 or lower, pH 12.5 or lower, pH 12.7 or lower, or pH 13 or lower.

[0154] Once the composite transition metal hydroxide particles are formed using the above method, the particles are separated from the reaction solution to obtain the composite transition metal hydroxide. Specifically, the reaction solution is filtered to separate the particles, and then the separated particles are washed and dried to obtain the composite transition metal hydroxide. At this time, processes such as grinding and / or classification may also be performed as needed.

[0155]

[0156] According to the present invention, the yttrium (Y)-containing raw material may be at least one selected from YCl3, Y2O3, Y(NO3)3, Y(OH)3, YSZ, Y2(SO4)3, and Y2S3, specifically at least one selected from Y2O3, Y(NO3)3, and Y(OH)3, and more specifically Y2O3. The yttrium-containing raw material may be added in an amount such that yttrium is 1,500 ppm to 4,500 ppm relative to the total weight of the composite transition metal hydroxide. Specifically, the yttrium-containing raw material contains yttrium in an amount of 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, 3,200 ppm or less, 3,300 ppm or less, 3,400 ppm or less, 3,500 ppm or less, It can be added in an amount such that the content is 3,600 ppm or less, 3,700 ppm or less, 3,800 ppm or less, 3,900 ppm or less, 4,000 ppm or less, 4,100 ppm or less, 4,200 ppm or less, 4,300 ppm or less, 4,400 ppm or less, or 4,500 ppm or less. In this case, since the grain size contained in one particle is large, the capacity and life performance of the battery can be further improved.

[0157]

[0158] 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.

[0159] According to the present invention, the composite transition metal hydroxide 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 composite transition metal hydroxide and the mole number (Li) of lithium included in the lithium-containing raw material is 1:1.0 to 1.1, 1:1.01 to 1.09, 1:1.02 to 1.08, 1:1.03 to 1.07, 1:1.04 to 1.07, or 1:1.05 to 1.07.

[0160]

[0161] (B) Step

[0162] The above step (B) is a step of manufacturing a sintered product by successively firing the mixture first at 750°C to 900°C, second at 920°C to 1,000°C, and third at 500°C to 800°C under an atmospheric atmosphere.

[0163]

[0164] According to the present invention, when the mixture is first fired at 750°C to 900°C, a reaction occurs between the lithium-containing raw material and the composite transition metal hydroxide, causing a change in the crystal structure, and polycrystalline secondary particles having small primary particle sizes are produced. Specifically, the first firing temperature may be 750°C or higher, 760°C or higher, 770°C or higher, 780°C or higher, 790°C or higher, 800°C or higher, 810°C or higher, 820°C or higher, 830°C or higher, 840°C or higher, or 850°C or higher, and 860°C or lower, 870°C or lower, 880°C or lower, 890°C or lower, or 900°C or lower. When the first firing temperature is within the above range, the reaction between the composite transition metal hydroxide and lithium progresses evenly, so that the cathode active material ultimately produced can be structurally stable and uniform. When the temperature is lower than 750°C, the reaction between lithium and the composite transition metal hydroxide does not proceed sufficiently, so that more than 10 primary particles are aggregated to form a cathode active material in the form of secondary particles during secondary firing, resulting in a problem of reduced life characteristics. When the temperature is higher than 900°C, the growth of the primary particles progresses rapidly, inducing non-uniform particle growth during secondary firing, resulting in a problem of reduced capacity.

[0165] According to the present invention, the first firing is performed in an air atmosphere, which is easy to maintain in a heat treatment atmosphere and is economical.

[0166] According to the present invention, the primary calcination may be performed for 2 to 10 hours. In this case, the reaction between the composite transition metal hydroxide and lithium ions can proceed appropriately, so that lithium can be evenly distributed throughout the positive electrode active material, and uniform particle growth can be achieved overall.

[0167]

[0168] Immediately after the first firing is completed, the temperature is continuously increased to 920°C to 1,000°C, and when the second firing is performed at 920°C to 1,000°C, the size of the primary particles increases and particles in the form of single particles are manufactured. When the second firing temperature is within the above range, the primary particles grow to an appropriate level, so that a positive electrode active material in the form of single particles can be manufactured, and the capacity characteristics and life characteristics can be improved. On the other hand, when the second firing temperature is less than 920°C, the size of the primary particles is small, so that an uneven positive electrode active material in the form of secondary particles that cannot be in the shape of single particles is manufactured, which causes a problem of a reduced lifespan. When it exceeds 1,000°C, the size of the primary particles becomes too large, so that the movement of lithium decreases, which causes a problem of an increase in resistance and a decrease in capacity characteristics.

[0169] The above secondary firing is performed in an air atmosphere, which is economical and easy to maintain.

[0170] According to the present invention, the secondary firing may be performed for 2 to 10 hours. In this case, the primary particles can grow to an appropriate degree, thereby improving capacity characteristics and lifespan characteristics.

[0171]

[0172] Immediately after the above-mentioned second firing is completed, the temperature is continuously lowered to 500℃ to 800℃, and when the third firing is performed at 500℃ to 800℃, a stabilization reaction on the surface occurs, and a fired product with increased stability of the crystal structure is manufactured. At this time, the fired product may be a lithium nickel cobalt manganese oxide in the form of a single particle composed of 10 or fewer primary particles and having a nickel content of 60 mol% or more among the total transition metal. When the third firing temperature is within the above range, the structural stability increases, so that the charge / discharge capacity and resistance can be improved. On the other hand, when the third firing temperature is less than 500℃, the structural stability of the positive electrode active material is lowered, which increases cation mixing, causing a problem of a decrease in life performance. When it exceeds 800℃, there is a problem of an increase in resistance and a decrease in charge capacity due to a structural change on the surface.

[0173] The above 3rd firing is performed in an air atmosphere, which is economical and easy to maintain.

[0174] According to the present invention, the third firing may be performed for 2 to 10 hours. In this case, the structural stability of the positive electrode active material is increased, thereby providing the advantage of increased charge / discharge capacity and efficiency.

[0175]

[0176] The method for manufacturing a positive electrode active material according to the present invention may further include (C) a step of pulverizing the sintered product, in order to improve capacity through uniform application of the positive electrode active material during electrode manufacturing.

[0177] According to the present invention, the above-mentioned fine grinding may be performed by air-flow grinding. In this case, grinding is possible within the target particle size range, which is advantageous in achieving a particle size optimized for capacity and life performance.

[0178] According to the present invention, the airflow grinding may be performed under a pressure of 1.5 to 5 bar. In this case, uniform grinding without damage to the primary particles can improve the charge / discharge capacity and life performance of the positive electrode active material.

[0179]

[0180] 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 nickel cobalt manganese oxide in the form of single particles).

[0181] 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, or 1,300 ppm or more, and 1,400 ppm or less, 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.

[0182] 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, or 2,200 ppm or more, and 2,500 ppm or less, 2,600 ppm or less, 2,700 ppm or less, 2,800 ppm or less, 2,900 ppm or less, 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.

[0183] According to the present invention, the aluminum raw material and the tungsten raw material can be mixed in an amount such that the total amount of coating elements Al and W relative to the total weight of the sintered product is 3,000 ppm to 6,000 ppm. Specifically, the aluminum raw material and the tungsten raw material have a total amount of coating elements Al and W of 3,000 ppm or more, 3,100 ppm or more, 3,200 ppm or more, 3,300 ppm or more, 3,400 ppm or more, 3,500 ppm or more, 3,600 ppm or more, 3,700 ppm or more, 3,800 ppm or more, 3,900 ppm or more, 4,000 ppm or more, 4,100 ppm or more, 4,200 ppm or more, 4,300 ppm or more, 4,400 ppm or more, or 4,500 ppm or more, and 4,600 ppm or less, 4,700 ppm or less, 4,800 ppm or less, 4,900 ppm or less, 5,000 ppm or less, It can be mixed in an amount such that the content is 5,100 ppm or less, 5,200 ppm or less, 5,300 ppm or less, 5,400 ppm or less, 5,500 ppm or less, 5,600 ppm or less, 5,700 ppm or less, 5,800 ppm or less, 5,900 ppm or less, or 6,000 ppm or less. In this case, the electrical conductivity of the resulting positive electrode active material can be improved and byproducts formed by side reactions with the electrolyte can be controlled, thereby improving the capacity characteristics and life characteristics of the battery.

[0184]

[0185] The above heat treatment can be performed in an air atmosphere, an oxygen atmosphere, or an inert atmosphere. Specifically, it can be performed in an air atmosphere because it is easy to maintain and economically advantageous.

[0186]

[0187] In addition, the heat treatment may be performed at a temperature of 400°C to 600°C. Specifically, the heat treatment may be performed at a temperature of 400°C or higher, 410°C or higher, 420°C or higher, 430°C or higher, 440°C or higher, 450°C or higher, 460°C or higher, 470°C or higher, 480°C or higher, 490°C or higher, or 500°C or higher, and 510°C or lower, 520°C or lower, 530°C or lower, 540°C or lower, 550°C or lower, 560°C or lower, 570°C or lower, 580°C or lower, 590°C or lower, or 600°C or lower. When the heat treatment temperature is within the above range, sufficient heat energy required for coating can be supplied. When the lithium nickel cobalt manganese oxide and the coating Al and W raw materials are mixed and then heat-treated in the above temperature range, a coating layer including the coating elements Al and W can be formed on the lithium nickel cobalt manganese oxide. The coating layer including the coating elements Al and W may partially cover (discontinuously) at least a portion of the lithium nickel cobalt manganese oxide, i.e., a region of the lithium nickel cobalt manganese oxide, or may cover (continuously) the entire region. The coating layer may be in the form of a film type, an island type, or a combination thereof.

[0188]

[0189] The above heat treatment may be performed for 3 to 9 hours. Specifically, the heat treatment may be performed for 3 hours or more, 4 hours or more, or 5 hours or more, or 6 hours or less, 7 hours or less, 8 hours or less, or 9 hours or less. When the heat treatment time is within the above range, heat energy can be supplied to a sufficient degree to form a coating layer.

[0190]

[0191] anode

[0192] The present invention provides a positive electrode comprising the positive electrode active material.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] 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.

[0200]

[0201] lithium secondary battery

[0202] 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.

[0203]

[0204] The above 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.

[0205]

[0206] 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.

[0207] 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.

[0208] The above negative electrode active material layer may optionally include a binder and a conductive material together with the negative electrode active material.

[0209] 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.

[0210] 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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218]

[0219] 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).

[0220] 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.

[0221] 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.

[0222] Accordingly, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0223] 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.

[0224]

[0225] 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.

[0226]

[0227] Examples and Comparative Examples

[0228] Example 1

[0229] 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 0.617 Co 0.06 Mn 0.32 Zr 0.003 (OH)2, average particle size (D) 50 ): 3.5㎛) and Y2O3 (input in an amount such that yttrium is 0.3 mol% of the 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+Zr) to the mole number of lithium included in Li2CO3 (Li) ((Ni+Co+Mn+Zr):Li) was 1:1.06, 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 to prepare a mixture.

[0230] After the above mixture was placed in a square alumina crucible (150 mm × 150 mm), it was first fired at 850°C for 6 hours in an air atmosphere, then the temperature was continuously raised to 955°C (heating rate: 1.25°C / min), fired a second time at 955°C for 3 hours, then the temperature was continuously lowered to 600°C (heating rate: 3°C / min), fired a third time at 600°C for 2 hours, and a fired product was manufactured.

[0231] Using a jet mill (Isaac E&C, 2-inch Jet Mill), the above-mentioned calcined product was finely ground by injecting 5 g per minute under a sample injection pressure of 6 bar and a grinding pressure of 4 bar.

[0232] The above-mentioned pulverized product was mixed with Al2O3 (input in an amount such that Al is 1,500 ppm based on the total weight of the sintered product) and WO3 (input in an amount such that W is 3,000 ppm based on the total weight of the sintered product), and then heat-treated at 500°C for 6 hours in an air atmosphere to manufacture a positive electrode active material including a coating layer containing Al and W.

[0233]

[0234] Example 2

[0235] 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 0.617 Co 0.06 Mn 0.32 Zr 0.003 (OH)2, average particle size (D) 50): 3.5㎛) and Y2O3 (input in an amount such that yttrium is 0.3 mol% of the 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+Zr) to the mole number of lithium included in Li2CO3 (Li) ((Ni+Co+Mn+Zr):Li) was 1:1.06, 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 to prepare a mixture.

[0236] 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 945°C (heating rate: 1.25°C / min), the second firing was performed at 945°C for 5 hours, the temperature was continuously decreased to 600°C (heating rate: 3°C / min), and the third firing was performed at 600°C for 6 hours and 30 minutes to manufacture a sintered product.

[0237] Using a jet mill (Isaac E&C, 2-inch Jet Mill), the above-mentioned calcined product was finely ground by injecting 5 g per minute under a sample injection pressure of 6 bar and a grinding pressure of 4 bar.

[0238] The above-mentioned pulverized product was mixed with Al2O3 (input in an amount such that Al is 1,500 ppm based on the total weight of the sintered product) and WO3 (input in an amount such that W is 3,000 ppm based on the total weight of the sintered product), and then heat-treated at 500°C for 6 hours in an air atmosphere to manufacture a positive electrode active material including a coating layer containing Al and W.

[0239]

[0240] Comparative Example 1

[0241] 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, average particle size (D) 50 ): 3.5㎛), ZrO2 (zirconium added in an amount such that 0.3 mol% of the above-mentioned complex transition metal hydroxide is added) and Y2O3 (yttrium added in an amount such that 0.3 mol% of the above-mentioned complex transition metal hydroxide is added) were sequentially mixed at 40 g (g: acceleration of gravity) 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+Zr) and the mole number of lithium included in Li2CO3 (Li) ((Ni+Co+Mn+Zr):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.

[0242] After the above mixture was placed in a square alumina crucible (150 mm × 150 mm), it was first fired at 850°C for 6 hours in an air atmosphere, then the temperature was continuously raised to 955°C (heating rate: 1.25°C / min), fired a second time at 955°C for 3 hours, then the temperature was continuously lowered to 600°C (heating rate: 3°C / min), fired a third time at 600°C for 2 hours, and a fired product was manufactured.

[0243] Using a jet mill (Isaac E&C, 2-inch Jet Mill), the above-mentioned calcined product was finely ground by injecting 5 g per minute under a sample injection pressure of 6 bar and a grinding pressure of 4 bar.

[0244] The above-mentioned pulverized product was mixed with Al2O3 (Evonik) (Al was added in an amount such that 1,500 ppm was added based on the total weight of the sintered product) and WO3 (Zenychem) (W was added in an amount such that 3,000 ppm was added based on the total weight of the sintered product), and then heat-treated at 500°C for 6 hours in an air atmosphere to manufacture a cathode active material including a coating layer containing Al and W.

[0245]

[0246] Comparative Example 2

[0247] 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, average particle size (D) 50 ): 3.5㎛), ZrO2 (zirconium added in an amount such that 0.3 mol% of the above-mentioned complex transition metal hydroxide is added) and Y2O3 (yttrium added in an amount such that 0.3 mol% of the above-mentioned complex transition metal hydroxide is added) were sequentially mixed at 40 g (g: acceleration of gravity) 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+Zr) and the mole number of lithium included in Li2CO3 (Li) ((Ni+Co+Mn+Zr):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.

[0248] 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 945°C (heating rate: 1.25°C / min), the second firing was performed at 945°C for 5 hours, the temperature was continuously decreased to 600°C (heating rate: 3°C / min), and the third firing was performed at 600°C for 6 hours and 30 minutes to manufacture a sintered product.

[0249] Using a jet mill (Isaac E&C, 2-inch Jet Mill), the above-mentioned calcined product was finely ground by injecting 5 g per minute under a sample injection pressure of 6 bar and a grinding pressure of 4 bar.

[0250] The above-mentioned pulverized product was mixed with Al2O3 (input in an amount such that Al is 1,500 ppm based on the total weight of the sintered product) and WO3 (input in an amount such that W is 3,000 ppm based on the total weight of the sintered product), and then heat-treated at 500°C for 6 hours in an air atmosphere to manufacture a positive electrode active material including a coating layer containing Al and W.

[0251]

[0252] Experimental example

[0253] Experimental Example 1: Particle Size Analysis of Positive Electrode Active Material (1)

[0254] Using SEM (FEI, Inspect F), SEM images (5,000×) of each of the positive electrode active materials manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 were obtained, and are shown in Fig. 1.

[0255] In addition, using an image processing program (LG Chemical, DX program), the boundaries of the primary particles existing in the five SEM images (5,000×) of each of the positive electrode active materials manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 were divided and displayed in random colors. Fig. 2 is a drawing in which the boundaries of the primary particles are divided and displayed in random colors by image processing the SEM images (5,000×) of each of the positive electrode active materials manufactured in Examples 1 and 2 and Comparative Examples 1 and 2.

[0256]

[0257] Using a drawing 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, 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 product of the calculated volume and particle diameter for each primary particle is calculated (V i D i ) is the total volume (V) calculated i ) is divided by the total sum of the primary particles to derive the volume average particle diameter of the primary particles, and the total sum of the derived particle diameters is divided by the number of primary particles to derive the number average particle diameter of the primary particles. Then, the PDI value is obtained according to Equation 1 described in this specification, and this is shown in Table 1 below.

[0258] And, using the drawing that divides the boundaries of the primary particles and randomly colors them, the particle diameters at the points that are 10%, 50%, and 90% of the cumulative volume distribution according to particle diameter are calculated from the particle diameters and volumes of all the primary particles produced, and D v,10 , D v,50 , D v,90 Check it out, D v,50and span((D v,90 -D v,10 ) / D v,50 ) values ​​are shown in Table 1 below.

[0259]

[0260] Experimental Example 2: Particle Size Analysis of Positive Electrode Active Material (2)

[0261] 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 1 below.

[0262] At this time, D 50 refers to the particle size at the 50% point of the cumulative volume distribution according to particle size.

[0263]

[0264] Classification Volume average particle size of primary particles (㎛) Number average particle size of primary particles (㎛) PDI span ((D v,90 -D v,10 ) / D v,50 ) value D v,50 D measured by PSA 50 (㎛)Example 12.5261.3321.8960.8132.553.54Example 22.6701.4471.8460.8092.663.98Comparative Example 12.8741.3602.1110.9102.873.82Comparative Example 22.5861.2122.1340.9382.573.81

[0265] Referring to Table 1 above, it can be confirmed that the positive electrode active materials of Examples 1 and 2 have a PDI value close to 1 and a low span value, and thus have a more uniform particle size than the positive electrode active materials of Comparative Examples 1 and 2.

[0266] Referring to FIG. 1, it can be confirmed that the positive electrode active materials of Examples 1 and 2 exist only in the form of single particles composed of 10 or fewer primary particles, whereas the positive electrode active materials of Comparative Examples 1 and 2 exist in the form of secondary particles composed of agglomerates of primary particles smaller than the primary particles of Examples 1 and 2, as well as in the form of single particles composed of primary particles that have grown to very large sizes.

[0267] Referring to FIG. 2, in the case of Examples 1 and 2, it can be seen that the primary particles expressed in different colors have a small number of clumped areas and primary particles of uniform size are evenly distributed, whereas in the case of Comparative Examples 1 and 2, the primary particles expressed in different colors appear to be clumped together and the individual sizes of the primary particles are not uniform.

[0268]

[0269] Experimental Example 3: ICP Analysis

[0270] Each of the sintered products (hereinafter referred to as lithium nickel cobalt manganese oxide) 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 nickel cobalt manganese oxide. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction to completely dissolve the lithium nickel cobalt manganese oxide, thereby preparing 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 nickel cobalt manganese oxide, the content of Zr (ppm) and the content of Y (ppm) present in the lithium nickel cobalt manganese oxide are shown in Table 2 below.

[0271] In addition, 0.1 g of the positive electrode active materials manufactured in the examples and comparative examples were taken, 1 ml of hydrochloric acid was added, and the positive electrode active material was dissolved by heating. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction to completely dissolve the positive electrode active material, thereby preparing a solution. Next, 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 content of Al (ppm) and W (ppm) present in the positive electrode active material are shown in Table 2 below.

[0272] Classification Lithium nickel cobalt manganese oxide composition Zr content (ppm) Y content (ppm) Al content (ppm) W content (ppm) Example 1 Li 1.0402 Ni 0.6173 Co 0.0606 Mn 0.3161 Zr 0.0033 Y 0.0027 O22,9802,4201,3552,288 Example 2Li 1.0412 Ni 0.6183 Co 0.0596 Mn 0.3161 Zr 0.0032 Y 0.0027 O22,9302,4301,3612,445 Comparative example 1Li 1.0407 Ni 0.6185 Co 0.0597 Mn 0.3162 Zr 0.0030 Y 0.0027 O22,7002,3801,2532,264Comparative example 2Li 1.0406 Ni 0.6175 Co 0.0587 Mn 0.3182 Zr 0.0029 Y 0.0027 O22,6802,4101,2972,253

[0273] Through the above Table 2, it was confirmed that the lithium nickel cobalt manganese oxide manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 had a composition represented by the above chemical formula 1 and included doping elements Zr and Y. In addition, it was confirmed that the positive electrode active materials manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 included a coating layer including Al and W.

[0274]

[0275] Experimental Example 4: Battery Performance Evaluation

[0276] The positive electrode active materials manufactured in the examples and comparative examples were mixed with each positive electrode active material, Super P conductive agent, and polyvinylidene fluoride (PVDF) binder in a ratio of 95:2:3 in an N-methylpyrrolidone (NMP) solvent to manufacture a positive electrode slurry. The positive electrode slurry was applied to one surface of an aluminum current collector, dried at 130°C, and rolled to manufacture a positive electrode.

[0277] 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.

[0278] For each half cell manufactured in this way, the initial charge capacity and initial discharge capacity were measured while charging to 4.45 V in CC (0.1 C)-CV mode at 25°C and discharging to 2.5 V in CC (0.1 C) mode, and the initial 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 0.1 C by the applied current.

[0279] Then, the capacity of the lithium secondary battery was measured by repeating the charge / discharge cycle 50 times at a constant current of 0.33 C in the range of 2.5 to 4.45 V at 45℃, and the percentage of the 50th cycle discharge capacity to the 1st cycle discharge capacity was defined as the capacity retention rate, which is shown in Table 3 below. In addition, the percentage of the DICR, which is defined as the voltage drop (△V) for 60 seconds in the 50th discharge cycle divided by the current, to the DCIR, which is defined as the voltage drop (△V) for 60 seconds in the 1st discharge cycle divided by the current, was defined as the resistance increase rate, which is shown in Table 3 below.

[0280] ClassificationInitial discharge capacity (mAh / g)Initial efficiency (%)DCIR (Ω)Capacity retention rate (%)Resistance increase rate (%)Example 1200.390.134.995.385.5Example 2199.590.134.295.581.8Comparative example 1198.890.035.694.392.1Comparative example 2197.889.836.093.8105.0

[0281] Referring to Table 1 and Table 3 above, the positive electrode active materials of Examples 1 and 2 not only have a single particle form, but also have a PDI index close to 1 and a low span value, so that it can be confirmed that the battery including them has superior battery capacity, initial efficiency, lifespan, and resistance performance compared to the battery including the positive electrode active materials of Comparative Examples 1 and 2.

Claims

1. Contains lithium nickel cobalt manganese oxide in the form of a single particle consisting of 10 or fewer primary particles, with a nickel content of 60 mol% or more among all transition metals; The above lithium nickel cobalt manganese oxide is doped with zirconium (Zr) and yttrium (Y). A positive electrode active material having a polydispersity index (PDI) value of 1.0 to 2.0 according to the following equation 1: [Formula 1] PDI = .

2. In claim 1, The above lithium nickel cobalt manganese oxide is a positive electrode active material having a composition represented by the following chemical formula 1: [Chemical Formula 1] Li 1+x Ni a1 Co b1 Mr c1 Zr d1 Y e1 M f1 O2 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, -0.1≤x≤0.1, 0.6≤a1<1, 0 <b1<0.4, 0<c1<0.4, 0<d1≤0.01, 0<e1≤0.01, 0≤f1≤0.1, a1+b1+c1+d1+e1+f1=1이다.

3. In claim 1, The above lithium nickel cobalt manganese oxide is a cathode active material doped with 1,500 ppm to 4,500 ppm of Zr and 1,500 ppm to 4,500 ppm of Y.

4. In claim 1, A positive electrode active material having an average volume particle size of the above primary particles of 2.4 ㎛ to 3.0 ㎛.

5. In claim 1, A positive electrode active material having an average particle size of the primary particles of 1.2 μm to 3.0 μm.

6. 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 4.1㎛.

7. In claim 1, The span of the above primary particle ((D v,90 -D v,10 ) / D v,50 ) positive electrode active material with a value of 0.9 or less.

8. In claim 1, D of the above primary particle v,50 A positive electrode active material having a diameter of 2.2㎛ to 3.2㎛.

9. In claim 1, The above positive electrode active material further includes a coating layer formed on the lithium nickel cobalt manganese oxide, The above coating layer is a positive electrode active material comprising Al, W or a combination thereof.

10. In claim 9, A positive electrode active material having an Al content included in the coating layer of 1,000 ppm to 2,000 ppm relative to the total weight of the positive electrode active material.

11. In claim 9, A positive electrode active material having a content of W included in the coating layer of 2,000 ppm to 4,000 ppm relative to the total weight of the positive electrode active material. 12.(A) A step of preparing a mixture by mixing a complex transition metal hydroxide having a composition represented by the following chemical formula 2, an yttrium-containing raw material, and a lithium-containing raw material; and (B) A method for manufacturing a cathode active material, comprising: a step of manufacturing a sintered product by successively firing the mixture at 750°C to 900°C in an air atmosphere, firing it at 920°C to 1,000°C in a second time, and firing it at 500°C to 800°C in a third time; [Chemical Formula 2] Ni a2 What b2 Mn c2 Zr d2 M' e2 (OH)2 In the above chemical formula 2, M' is at least one selected from W, Cu, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al, 0.6≤a2<1, 0 <b2<0.4, 0<c2<0.4, 0<d2≤0.01, 0≤e2≤0.1, a2+b2+c2+d2+e2=1이다.

13. In claim 12, A method for manufacturing a positive electrode active material, wherein the above first firing is performed for 2 to 10 hours.

14. In claim 12, A method for manufacturing a positive electrode active material, wherein the above secondary firing is performed for 2 to 10 hours.

15. In claim 12, A method for manufacturing a positive electrode active material, wherein the above third firing is performed for 2 to 10 hours.

16. In claim 12, (C) A method for producing a positive electrode active material, further comprising a step of pulverizing the above-mentioned product.

17. In claim 16, A method for producing a positive electrode active material, wherein the above-mentioned fine grinding is performed by air-flow grinding.

18. In claim 17, A method for producing a positive electrode active material, wherein the above-mentioned airflow grinding is performed under a pressure of 2.5 bar to 4 bar.

19. In claim 12, (C') A method for producing a positive electrode active material, further comprising the step of mixing the sintered product with at least one selected from aluminum raw materials and tungsten raw materials and then performing a heat treatment to form a coating layer including at least one selected from Al and W on the sintered product.

20. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 11.

21. The anode according to claim 20; cathode; a separator interposed between the anode and the cathode; and A lithium secondary battery comprising an electrolyte.

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