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

Abstract

The present invention relates to a cathode active material, a method for preparing same, and a cathode and a lithium secondary battery comprising same, the cathode active material comprising: a lithium composite transition metal oxide in a single particle form consisting of 10 or less primary particles and having a composition represented by chemical formula 1 described in the present specification; and a coating layer containing a coating element (M) formed on the lithium composite transition metal oxide, the coating element (M) being at least one selected from Al, W, Cu, Zr, Ni, Co. Sr. Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si, wherein the cathode active material has a degree of single-particle formation (χ) exceeding 0.5 according to formula 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. 10-2023-0151121, 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 including the same.

[0005]

[0006] As technological development and demand for mobile devices increase, 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-cobalt composite metal oxides are commonly used as cathode active materials in lithium secondary batteries. Among these, lithium-cobalt composite metal oxides, such as LiCoO2, are primarily used due to their high operating voltage and superior capacity characteristics. However, LiCoO2 suffers from poor thermal properties due to crystal structure instability following delithiation. Furthermore, its high cost limits its widespread use as a power source in fields such as electric vehicles.

[0008] As materials to replace LiCoO2, lithium manganese composite metal oxides (such as LiMnO2 or LiMn2O4), lithium iron phosphate compounds (such as LiFePO4), or lithium nickel composite metal oxides (such as LiNiO2) have been developed. Among these, research and development is being more actively conducted on lithium nickel composite metal oxides, which have a high reversible capacity of approximately 200 mAh / g and can easily be used to implement large-capacity batteries. However, LiNiO2 has poor thermal stability compared to LiCoO2, and there is a problem that if an internal short circuit occurs due to external pressure while charged, the positive electrode active material itself decomposes, causing the battery to rupture and catch fire.

[0009] Accordingly, as a method to improve the low thermal stability while maintaining the excellent reversible capacity of LiNiO2, nickel-cobalt-manganese lithium composite transition metal oxides in which some of the Ni is replaced with Mn and Co, and nickel-manganese-aluminum lithium composite transition metal oxides in which some of the Ni is replaced with Mn and Al have been developed.

[0010] Meanwhile, lithium-based transition metal oxides with high nickel content suffer from further deterioration in structural and chemical stability, greater difficulty in ensuring thermal stability, and cost issues associated with high heat treatment temperatures. To improve stability, various studies are being conducted, including the inclusion of doping elements in lithium-based transition metal oxides.

[0011] Therefore, there is a need to develop a cathode active material with a high nickel content and improved stability that can implement a lithium secondary battery with improved capacity and life characteristics.

[0012]

[0013] [Prior Art Literature]

[0014] [Patent Document]

[0015] (Patent Document 1) Korean Patent Publication No. 10-2021-0007808

[0016]

[0017] The present invention is intended to solve the above problems, and to provide a positive electrode active material and a method for manufacturing the same that can improve the capacity and life characteristics of a battery.

[0018] In addition, the present invention seeks to provide a positive electrode and a lithium secondary battery having excellent capacity and lifespan characteristics, including the positive electrode active material as described above.

[0019]

[0020] (1) The present invention provides a cathode active material comprising a lithium composite transition metal oxide in the form of a single particle composed of 10 or fewer primary particles and having a composition represented by the following chemical formula 1; and a coating layer including a coating element (M) formed on the lithium composite transition metal oxide; wherein the coating element (M) is at least one selected from Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si, and has a single particle crystallinity (χ) according to the following chemical formula 1 of greater than 0.5.

[0021] [Chemical Formula 1]

[0022] Li 1+x Ni a Co b Mn c M 1 d O2

[0023] In the above chemical formula 1, the M 1 is at least one selected from Zr, Y, W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al, and -0.1≤x≤0.1, 0.6≤a<1, 0 <b<0.4, 0<c<0.4, 0≤d≤0.1, a+b+c+d=1, 0.25≤a-c≤0.45이고,

[0024] [Formula 1]

[0025] am.

[0026] (2) The present invention provides a positive electrode active material in the above (1), wherein in the above chemical formula 1, a is 0.6 or more and 0.75 or less.

[0027] (3) In the present invention, in the above (1) or (2), in the above chemical formula 1, the ac is 0.25 <a-c<0.34인 것인 양극 활물질을 제공한다.

[0028] (4) The present invention provides a positive electrode active material in which the content of the coating element (M) included in the coating layer is 3,000 ppm or more and 5,500 ppm or less with respect to the total weight of the lithium composite transition metal oxide in any one of (1) to (3).

[0029] (5) The present invention provides a positive electrode active material in any one of the above (1) to (4), wherein the coating layer includes a Li-MO compound, and M is at least one selected from Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si.

[0030] (6) The present invention provides a positive electrode active material in any one of the above (1) to (5), wherein the coating element (M) is at least one selected from Al and W.

[0031] (7) The present invention is characterized in that the average particle diameter (D') of the primary particles is in any one of the above (1) to (6). 50 ) provides a positive electrode active material having a size of 2㎛ or more and 5㎛ or less.

[0032] (8) The present invention, in any one of the above (1) to (7), has an average particle diameter (D) of the positive electrode active material. 50 ) provides a positive electrode active material having a size of 3㎛ or more and 5㎛ or less.

[0033] (9) The present invention provides a positive electrode active material having a single particle magnetization degree (χ) of 0.6 or more and 0.9 or less in any one of the above (1) to (8).

[0034] (10) The present invention provides a method for producing a positive electrode active material according to (1), comprising the steps of: (A) mixing a composite transition metal hydroxide and a lithium (Li)-containing raw material and calcining to produce a lithium composite transition metal oxide; and (B) mixing the lithium composite transition metal oxide and a raw material containing a coating element (M) and then heat-treating the mixture to form a coating layer; wherein the calcination is performed at a temperature of 800°C or higher and 1,100°C or lower, and the coating element (M) is at least one selected from among Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si.

[0035] (11) The present invention provides a method for producing a positive electrode active material, wherein, in the above (10), the raw material containing the coating element (M) is at least one selected from oxides, carbonates, nitrates, hydroxides, oxyhydroxides, and halides containing the coating element (M).

[0036] (12) The present invention provides a method for manufacturing a positive electrode active material, wherein, in the above (10) or (11), the raw material containing the coating element (M) is mixed so that the coating element (M) content is 3,000 ppm or more and 5,500 ppm or less with respect to the total weight of the lithium composite transition metal oxide.

[0037] (13) The present invention is a method for producing a positive electrode active material, wherein the heat treatment is performed at a temperature of 400°C or higher and 600°C or lower in any one of the above (10) to (12).

[0038] (14) The present invention provides a positive electrode comprising a positive electrode active material according to any one of (1) to (9).

[0039] (15) The present invention provides a lithium secondary battery including a positive electrode according to (14) above.

[0040]

[0041] The cathode active material according to the present invention comprises a lithium composite transition metal oxide having a molar fraction difference between nickel and manganese within a specific range, and by forming a coating layer on the lithium composite transition metal oxide, the average particle size of primary particles, etc. can be controlled to maintain electrode density while reducing side reactions with the electrolyte and improving electrical conductivity. Accordingly, the capacity characteristics and life characteristics of the cathode and secondary battery including the cathode active material are improved.

[0042] 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.

[0043]

[0044] Figure 1 is a SEM image (5K magnification) of the positive electrode active material manufactured in Example 1.

[0045] Figure 2 is a SEM image (5K magnification) of the positive electrode active material manufactured in Example 2.

[0046] Figure 3 is a SEM image (5K magnification) of the positive electrode active material manufactured in Comparative Example 1.

[0047] Figure 4 is a SEM image (5K magnification) of the positive electrode active material manufactured in Comparative Example 3.

[0048] Figure 5 is a SEM image (20K magnification) of the positive electrode active material manufactured in Example 1.

[0049] Figure 6 is a SEM image (50K magnification) of the positive electrode active material manufactured in Example 1.

[0050]

[0051] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0052] 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 idea 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 way.

[0053] In this specification, it should be understood that terms such as “include,” “have,” or “have” 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.

[0054] 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.

[0055] 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.

[0056] In this specification, 'primary particle' means the smallest particle unit recognized when observing a positive electrode active material using a scanning electron microscope (SEM), and 'secondary particle' means a secondary structure formed by the aggregation of multiple primary particles.

[0057] In this specification, the content of each element in the lithium composite transition metal oxide may be measured through ICP (Inductive Coupled Plasma) analysis using an inductively coupled plasma optical emission spectrometer (ICP-OES; Optima 7300DV, PerkinElmer).

[0058] In this specification, the particle size of the primary particles may be calculated by calculating the area of ​​each primary particle through the number of pixels corresponding to each of n primary particles present in the SEM image, and calculating the particle size of each primary particle present in the SEM image using the diameter of a circle having the same area as the area of ​​each primary particle. In addition, in this specification, the average particle size (D') of the primary particles 50 ) can be defined as the particle size corresponding to 50% of the volume cumulative distribution in the particle size distribution curve (graph curve of particle size distribution) of each particle. The average particle size (D') of the primary particles 50 ) can be measured by taking the volume of a sphere whose radius is half of the particle diameter of the primary particle as the volume of the primary particle, and then calculating the particle diameter at the point where 50% of the cumulative volume distribution according to the particle diameter in the result of calculating the volume of the primary particle is obtained.

[0059] In this specification, the average particle diameter (D) of the positive electrode active material 50 ) can be defined as the particle size corresponding to 50% of the volume cumulative distribution in the particle size distribution curve (graph curve of particle size distribution) of each particle. The average particle size (D) of the positive electrode active material 50 ) can be measured by dispersing the target powder in a dispersion medium, introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac's S3500), measuring the difference in diffraction pattern according to particle size when the particles pass through the laser beam, calculating the particle size distribution, and calculating the particle diameter at the point where it becomes 50% of the volume cumulative distribution according to particle size in the measuring device.

[0060]

[0061] positive electrode active material

[0062] Hereinafter, the positive electrode active material according to the present invention will be described.

[0063]

[0064] The cathode active material according to the present invention is in the form of a single particle composed of 10 or fewer primary particles, and includes a lithium composite transition metal oxide having a composition represented by the following chemical formula 1; and a coating layer including a coating element (M) formed on the lithium composite transition metal oxide; wherein the coating element (M) is at least one selected from Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si, and has a single particle degree (χ) according to the following chemical formula 1 of greater than 0.5.

[0065] [Chemical Formula 1]

[0066] Li 1+x Ni a Co b Mn c M 1 d O2

[0067] In the above chemical formula 1,

[0068] Above M 1 is at least one selected from Zr, Y, W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al, and -0.1≤x≤0.1, 0.6≤a<1, 0 <b<0.4, 0<c<0.4, 0≤d≤0.1, a+b+c+d=1, 0.25≤a-c≤0.45이고,

[0069] [Formula 1]

[0070] am.

[0071] The present inventors have found that a lithium secondary battery having improved capacity characteristics and cycle life characteristics can be implemented when the lithium composite transition metal oxide has a high nickel content and a lithium composite transition metal oxide having a specific range of mole fraction differences between nickel and manganese, a coating layer including a coating element (M) formed on the lithium composite transition metal oxide, and a cathode active material having a specific range of single particle size distribution is included. Specifically, the average particle diameter of the lithium composite transition metal oxide primary particles is determined according to the difference in mole fraction between nickel and manganese. When the average particle diameter of the primary particles increases, the electrode density decreases and the side reaction with the electrolyte decreases, and when the average particle diameter of the primary particles decreases, the electrode density increases and the side reaction with the electrolyte increases. In addition, by including the coating layer formed on the lithium composite transition metal oxide, electrical conductivity can be improved and byproducts formed by the side reaction with the electrolyte can be controlled. The present inventors have found that the positive electrode active material comprises a lithium composite transition metal oxide having a difference in the molar fraction of nickel and manganese within a specific range and a coating layer including a coating element (M) formed on the lithium composite transition metal oxide, thereby increasing the average particle diameter (D') of the primary particles of the positive electrode active material. 50 ) by appropriately controlling the single particle size according to Equation 1 described in this specification, the capacity characteristics, resistance characteristics, and life characteristics of the positive electrode active material can be improved when the single particle size is within a specific range, thereby completing the present invention.

[0072] Meanwhile, when the difference in the mole fraction of nickel and manganese contained in the lithium composite transition metal oxide with a high nickel content is not within a specific range or the degree of single particle size is 0.5 or less, the average particle diameter (D') of the primary particles of the lithium composite transition metal oxide 50) is small, there is a problem with the life characteristics, or when rolling for electrode manufacturing or operating the cell, particle breakage occurs due to grain boundaries, the grain boundary area in contact with the electrolyte increases significantly, and gas generation due to side reactions with the electrolyte increases, so there are problems with the life characteristics and resistance characteristics. In addition, when the coating layer including the coating element (M) formed on the lithium composite transition metal oxide with a high nickel content is not included, the electrical conductivity is poor, and there are problems with the capacity characteristics, resistance characteristics, and life characteristics due to by-products formed due to side reactions with the electrolyte.

[0073]

[0074] The lithium composite transition metal oxide is in the form of a single particle composed of 10 or fewer primary particles. That is, the lithium composite transition metal oxide is in the form of a single particle or a single particle composed of 2 to 10 aggregated particles. The single particle form is distinguished from a secondary particle composed of more than 10 aggregated primary particles. When the lithium composite transition metal oxide has a single particle form, the stability is excellent, and even when a positive electrode active material including the same is rolled, the positive electrode active material does not break or crack, so that a side reaction between the positive electrode active material and the electrolyte can be reduced. As a result, the durability against volume change during charge and discharge of the battery is improved, so that the life characteristics can be improved. When the lithium composite transition metal oxide has a form of a secondary particle, when a positive electrode active material including the same is rolled, the positive electrode active material is broken or cracked, so that a side reaction between the positive electrode active material and the electrolyte occurs, and as a result, the durability against volume change during charge and discharge of the battery is inferior, and there is a problem of inferior life characteristics.

[0075]

[0076] Above M 1 is a doping element, specifically the above M 1M may be at least one selected from Zr, Y, W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al. 1 Although it is not essential, if included in an appropriate amount, the particle shape of the positive electrode active material can be improved and the stability of the crystal structure can be enhanced.

[0077] Meanwhile, 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, or 0.03 or more, and may be 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 0.1 or less. When x satisfies the above range, high capacity characteristics and high energy density per unit volume can be realized.

[0078] The above a is the molar fraction of nickel (Ni) among the total metals excluding lithium in the lithium composite transition metal oxide, and may be 0.6 or more, 0.61 or more, 0.62 or more, 0.63 or more, or 0.64 or more, and may be 0.65 or less, 0.66 or less, 0.67 or less, 0.68 or less, 0.69 or less, 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. High-capacity characteristics can be implemented, and in particular, when a is 0.6 or more and 0.75 or less, high energy density is exhibited when driving at high voltage, so that high-capacity characteristics can be implemented.

[0079] The above b is the mole fraction of cobalt (Co) among the total metals excluding lithium in the lithium composite transition metal oxide, and may be greater than 0, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, or 0.06 or more, and may be 0.07 or less, 0.08 or less, 0.09 or less, 0.1 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, 0.2 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, 0.3 or less, It may be 0.31 or less, 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 b satisfies the above range, stability can be improved and rate characteristics can be enhanced during the charge and discharge process.

[0080] The above c is the mole fraction of manganese (Mn) among the total metals excluding lithium in the lithium composite transition metal oxide, and is greater than 0, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, 0.15 or more, 0.16 or more, 0.17 or more, 0.18 or more, 0.19 or more, 0.2 or more, 0.21 or more, 0.22 or more, 0.23 or more, 0.24 or more, 0.25 or more, 0.26 or more, 0.27 or more, 0.28 or more, 0.29 or more, 0.3 or more, or It can be 0.31 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 c 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.

[0081] The above d is M among all metals except lithium in the lithium complex transition metal oxide. 1 The molar fraction of d may be 0 or more, 0.001 or more, 0.002 or more, 0.003 or more, or 0.004 or more, and may be 0.005 or less, 0.006 or less, 0.007 or less, 0.008 or less, 0.009 or less, 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 0.1 or less. When d satisfies the above range, the stability of the crystal structure of the positive electrode active material may be improved and the particle shape may be improved.

[0082] In addition, the above a, c may be ac of 0.25 or more, greater than 0.25, 0.26 or more, 0.27 or more, 0.28 or more, 0.29 or more, 0.3 or more, or 0.31 or more, and less than 0.34, 0.34 or less, 0.35 or less, 0.36 or less, 0.37 or less, 0.38 or less, 0.39 or less, 0.4 or less, 0.41 or less, 0.42 or less, 0.43 or less, 0.44 or less, or 0.45 or less. When the above ac satisfies the above range, the average particle diameter (D') of the primary particles of the positive electrode active material 50 ) can be appropriately adjusted to control the electrode density and side reactions with the electrolyte, and to improve the capacity characteristics and life characteristics. When the above ac is less than 0.25, the average particle diameter (D') of the primary particles of the positive electrode active material 50 ) decreases, there is a problem of poor life characteristics because the side reaction with the electrolyte increases, and when it exceeds 0.45, there is a problem of poor capacity characteristics because the electrode density decreases. In particular, when ac exceeds 0.25 and is less than 0.34, the life characteristics and resistance characteristics can be improved while maintaining the charge / discharge capacity of the secondary battery.

[0083] A coating layer including a coating element (M) formed on the lithium composite transition metal oxide; wherein the coating element (M) is at least one selected from Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si. When the coating layer includes the coating element (M), electrical conductivity can be improved and by-products formed by a side reaction with the electrolyte can be controlled, thereby improving capacity characteristics, resistance characteristics, and life characteristics. Specifically, the coating element (M) may be at least one selected from Al and W. In this case, there is an effect of suppressing the generation of by-products in the form of hydrogen fluoride and exhibiting high-capacity characteristics at a high rate. On the other hand, when the coating layer including the coating element (M) formed on the lithium composite transition metal oxide is not included, there is a problem that the electrical conductivity is inferior and the capacity characteristics, resistance characteristics, and life characteristics are inferior due to by-products formed by a side reaction with the electrolyte.

[0084]

[0085] The cathode active material according to the present invention has a single particle size (χ) of greater than 0.5 according to Equation 1 described herein. Specifically, the single particle size (χ) may be greater than 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, or 0.62, and may be 0.87 or less, 0.88 or less, 0.89 or less, 0.90 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 1 or less. When the single particle size distribution (χ) is within the above range, it can be seen that the lithium composite transition metal oxide of the present invention has a single particle form in which agglomeration between primary particles is suppressed. In particular, when the single particle size distribution (χ) is 0.6 or more and 0.9 or less, the structural stability is improved, so that when rolling for electrode manufacturing or when operating a cell, particle breakage is suppressed, the grain boundary area in contact with the electrolyte is reduced, and gas generation due to side reactions with the electrolyte is reduced, thereby improving the life characteristics and resistance characteristics of the secondary battery. On the other hand, when the single particle size distribution is 0.5 or less, when rolling for electrode manufacturing or when operating a cell, particle breakage due to grain boundaries occurs, the grain boundary area in contact with the electrolyte is greatly increased, and gas generation due to side reactions with the electrolyte is increased, thereby deteriorating the life characteristics.

[0086]

[0087] According to one embodiment of the present invention, the content of the coating element (M) included in the coating layer may be 3,000 ppm or more and 5,500 ppm or less with respect to the total weight of the lithium composite transition metal oxide. The content of the coating element (M) may be 3,000 ppm or more, or 3,100 ppm or more, based on the total weight of the lithium composite transition metal oxide, and may be 3,200 ppm or less, 3,300 ppm or less, 3,400 ppm or less, 3,500 ppm or less, 3,600 ppm or less, 3,700 ppm or less, 3,800 ppm or less, 3,900 ppm or less, 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, 4,500 ppm or less, 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, 5,100 ppm Below, it may be 5,200 ppm or less, 5,300 ppm or less, 5,400 ppm or less, or 5,500 ppm or less. When the content of the coating element (M) is within the above range, the electrical conductivity can be improved and by-products formed by side reactions with the electrolyte can be controlled, thereby improving the capacity characteristics, resistance characteristics, and life characteristics of the positive electrode active material.

[0088]

[0089] According to one embodiment of the present invention, the coating layer includes a Li-MO compound, and M may be at least one selected from Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si. Specifically, in the case of a Li-Al-O compound, a Li-WO compound, or a combination thereof, electrical conductivity can be improved and byproducts formed by a side reaction with an electrolyte can be controlled, thereby improving capacity characteristics, resistance characteristics, and life characteristics of the positive electrode active material.

[0090]

[0091] According to one embodiment of the present invention, the average particle diameter (D') of the primary particles 50 ) may be 2㎛ or more and 5㎛ or less. Specifically, the average particle diameter (D') of the primary particles 50 ) may be 2 ㎛ or more, 2.1 ㎛ or more, 2.2 ㎛ or more, 2.3 ㎛ or more, 2.4 ㎛ or more, 2.41 ㎛ or more, 2.42 ㎛ or more, 2.43 ㎛ or more, 2.44 ㎛ or more, 2.45 ㎛ or more, 2.46 ㎛ or more, 2.47 ㎛ or more, 2.48 ㎛ or more, or 2.49 ㎛ or more, and may be 3.4 ㎛ or less, 3.5 ㎛ or less, 3.6 ㎛ or less, 3.7 ㎛ or less, 3.8 ㎛ or less, 3.9 ㎛ or less, 4 ㎛ or less, 4.1 ㎛ or less, 4.2 ㎛ or less, 4.3 ㎛ or less, 4.4 ㎛ or less, 4.5 ㎛ or less, 4.6 ㎛ or less, 4.7 ㎛ or less, 4.8 ㎛ or less, 4.9 ㎛ or less, or 5 ㎛ or less. The average particle diameter (D') of the above primary particles 50 ) is within the above range, the side reaction between the positive active material and the electrolyte is reduced, so that the life characteristics can be improved, and the lithium diffusion path inside the particle is shortened, so that the resistance characteristics can be improved.

[0092]

[0093] According to one embodiment of the present invention, the average particle diameter (D) of the positive electrode active material 50 ) may be 3㎛ or more and 5㎛ or less. Specifically, the average particle diameter (D) of the positive electrode active material 50) may be 3 ㎛ or more, 3.1 ㎛ or more, 3.2 ㎛ or more, 3.3 ㎛ or more, 3.4 ㎛ or more, 3.5 ㎛ or more, 3.6 ㎛ or more, 3.7 ㎛ or more, 3.8 ㎛ or more, or 3.9 ㎛ or more, and may be 4.02 ㎛ or less, 4.03 ㎛ or less, 4.04 ㎛ or less, 4.05 ㎛ or less, 4.06 ㎛ or less, 4.07 ㎛ or less, 4.08 ㎛ or less, 4.09 ㎛ or less, 4.1 ㎛ or less, 4.2 ㎛ or less, 4.3 ㎛ or less, 4.4 ㎛ or less, 4.5 ㎛ or less, 4.6 ㎛ or less, 4.7 ㎛ or less, 4.8 ㎛ or less, 4.9 ㎛ or less, or 5 ㎛ or less. The average particle diameter (D of the positive electrode active material 50 ) is within the above range, excellent electrode density can be achieved and structural stability can be improved.

[0094]

[0095] Method for manufacturing positive electrode active material

[0096] Next, a method for manufacturing the positive electrode active material of the present invention will be described. The method for manufacturing the positive electrode active material of the present invention is a method for manufacturing the positive electrode active material according to the present invention.

[0097]

[0098] A method for manufacturing a cathode active material according to the present invention comprises the steps of (A) mixing a composite transition metal hydroxide and a lithium (Li)-containing raw material and calcining to manufacture a lithium composite transition metal oxide; and (B) mixing the lithium composite transition metal oxide and a raw material containing a coating element (M) and then heat-treating the mixture to form a coating layer; wherein the calcination is performed at a temperature of 800°C or higher and 1,100°C or lower, and the coating element (M) is at least one selected from among Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si.

[0099]

[0100] The cathode active material according to the present invention described above can be manufactured by appropriately controlling the type of raw material, the mixing ratio of raw materials, the heat treatment temperature, the sintering and heat treatment time, etc.

[0101]

[0102] Hereinafter, each step of the present invention will be described in detail.

[0103] (A) Step

[0104] The method for manufacturing a cathode active material according to the present invention includes the step (A) of mixing and calcining a composite transition metal hydroxide and a lithium (Li)-containing raw material to manufacture a lithium composite transition metal oxide.

[0105] The above complex transition metal hydroxide can be produced through a coprecipitation reaction by introducing a complex transition metal aqueous solution, an ammonium cation complex, and a basic compound into a reactor.

[0106] The above complex transition metal-containing solution may contain nickel (Ni), cobalt (Co), and manganese (Mn).

[0107] The above-mentioned composite transition metal aqueous solution can be prepared by dissolving a transition metal-containing raw material in a solvent such as water, and for example, can be prepared by dissolving a nickel (Ni)-containing raw material, a cobalt (Co)-containing raw material, and a manganese (Mn)-containing raw material in water. That is, the above-mentioned composite transition metal-containing solution can include a nickel (Ni)-containing raw material, a cobalt (Co)-containing raw material, and a manganese (Mn)-containing raw material. In addition, if necessary, the above-mentioned composite transition metal-containing solution can further include a metal-containing raw material containing a transition metal other than nickel (Ni), cobalt (Co), and manganese (Mn) (for example, at least one selected from Zr, Y, W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si, and Al).

[0108] The above nickel (Ni) containing raw material is NiSO 4,At least one selected from the group consisting of NiO, Ni(OH)2, NiOㆍOH, NiCO3ㆍ2Ni(OH)2ㆍ4H2O, NiC2O4ㆍ2H2O, Ni(NO3)2ㆍ6H2O, fatty acid nickel, and nickel halides may be used, and a mixture of one or two or more of these may be used.

[0109] The above cobalt (Co)-containing raw material may be at least one selected from the group consisting of Co(OH)2, Co3O4, CoOㆍOH, Co(OCOCH3)2ㆍ4H2O, Co(NO3)2ㆍ6H2O or Co(SO4)2ㆍ7H2O, fatty acid cobalt, and cobalt halides, and a mixture of one or two or more of these may be used.

[0110] The above manganese (Mn)-containing raw material may be at least one selected from the group consisting of MnCO3, Mn2O3, MnO2, Mn3O4, Mn(NO3)2, manganese acetate, manganese dicarboxylate, manganese citrate, manganese salts of fatty acid manganese, oxyhydroxides, and halides of manganese chloride, and a mixture of one or two or more of these may be used.

[0111] The above metal-containing raw material may be at least one selected from the group consisting of carbonates, nitrates, hydroxides, oxides, oxyhydroxides, and halides containing at least one transition metal other than nickel (Ni), cobalt (Co), and manganese (Mn), and a mixture of one or two or more of these may be used.

[0112] Nickel (Ni)-containing raw materials, cobalt (Co)-containing raw materials, and manganese (Mn)-containing raw materials can be used in appropriate amounts considering the content of each metal element in the composite transition metal hydroxide being manufactured.

[0113]

[0114] Meanwhile, the ammonium cation complex forming agent may include at least one compound selected from the group consisting of NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3, and may be introduced into the reactor in the form of a solution in which the compound is dissolved in a solvent. At this time, 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.

[0115]

[0116] The basic compound may be at least one compound selected from the group consisting of NaOH, KOH, and Ca(OH)2, and may be introduced into the reactor in the form of a solution in which the compound is dissolved in a solvent. At this time, the solvent may be water, or a mixture of water and an organic solvent (specifically, alcohol, etc.) that can be uniformly mixed with water.

[0117] When a complex transition metal-containing solution, an ammonium cation complex forming agent, and a basic compound are introduced into a reactor as described above, precursor particles in the form of a complex transition metal hydroxide are generated due to a coprecipitation reaction between the transition metal ions in the complex transition metal-containing solution and the hydroxide ions of the basic compound.

[0118] The above coprecipitation reaction may be performed for 1 hour or more and 50 hours or less. 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 precursor particles can be sufficiently controlled.

[0119] At this time, the basic compound 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 or higher and 13 or lower. Specifically, it may be performed at a pH of 10 or higher, 10.5 or higher, 11 or higher, or 11.5 or higher, and at a pH of 12 or lower, 12.5 or lower, 12.7 or lower, or 13 or lower.

[0120] Once the precursor particles are formed by the above method, the particles are separated from the reaction solution to obtain a complex transition metal hydroxide. Specifically, the reaction solution is filtered to separate the precursor particles, and then the separated precursor particles are washed and dried to obtain a complex transition metal hydroxide. At this time, processes such as grinding and / or classification may also be performed as needed.

[0121]

[0122] The above complex transition metal hydroxide is Ni p Co q Mn r M2 s (OH)2(M above 2 is at least one selected from Zr, Y, W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al, and the p, q, r, s are 0.6≤p<1, 0 <q<0.4, 0<r<0.4, 0≤s≤0.1, p+q+r+s=1이다.)로 표시되는 조성을 가질 수 있다.

[0123]

[0124] The above lithium (Li)-containing raw material may be at least one selected from the group consisting of LiOH, Li2CO3, LiNO3, LiNO2, LiOHㆍH2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li acetate, Li dicarboxylic acid, Li citrate, Li fatty acid, alkyl lithium, and lithium halides, and a mixture of one or two or more thereof may be used. Specifically, considering that the melting point of the lithium (Li)-containing raw material is similar to the sintering temperature and considering economic feasibility, Li2CO3 may be used.

[0125]

[0126] The above mixing can be done by dry mixing or wet mixing. When mixing each component through dry mixing, the firing process can be performed without a separate drying process. When mixing each component through wet mixing, the mixture can be prepared by adding it to a solvent, specifically water, or a mixture of water and an organic solvent (specifically, alcohol, etc.) that can be uniformly mixed with water, or a solution containing each raw material, specifically an aqueous solution, is prepared, and then the mixed components are mixed and spray-dried before the firing process is performed. Each raw material and composite transition metal hydroxide can be used in an appropriate amount considering the content of each metal element in the lithium composite transition metal oxide to be finally manufactured.

[0127]

[0128] According to one embodiment of the present invention, in step (A), the composite transition metal hydroxide and the lithium (Li)-containing raw material can be mixed in an amount such that the raw material has a composition represented by the chemical formula 1.

[0129]

[0130] The above firing is performed at a temperature of 800°C or higher and 1,100°C or lower. Specifically, the firing is performed at 800°C or higher, 810°C or higher, 820°C or higher, 830°C or higher, 840°C or higher, 850°C or higher, 860°C or higher, 870°C or higher, 880°C or higher, 890°C or higher, 900°C or higher, 910°C or higher, 920°C or higher, 930°C or higher, or 940°C or higher, and 950°C or lower, 960°C or lower, 970°C or lower, 980°C or lower, 990°C or lower, 1,000°C or lower, 1,010°C or lower, 1,020°C or lower, 1,030°C or lower, 1,040°C or lower, 1,050°C or lower, 1,060°C or lower, 1,070°C or lower, 1,080°C or lower, 1,090°C or lower, or It is performed under a temperature of 1,100℃ or lower. When the sintering temperature is within the above range, the primary particles grow to an appropriate degree, thereby improving the capacity characteristics and life characteristics. When performed under a temperature of less than 800℃, the particle growth is insufficient, so that more than 10 primary particles form agglomerates of positive electrode active material in the form of secondary particles, which causes a problem of reduced life characteristics. When performed under a temperature exceeding 1,100℃, the primary particles overgrow and the lithium movement decreases, which causes a problem of increased resistance and reduced capacity characteristics.

[0131]

[0132] The above firing can be performed under an air atmosphere, an oxygen atmosphere, or an inert atmosphere. Specifically, it can be performed under an air atmosphere because it is easy to maintain the firing atmosphere and is advantageous from an economic perspective.

[0133]

[0134] The above-mentioned calcination may be performed for 10 hours or more and 18 hours or less. Specifically, it may be performed for 10 hours or more, 11 hours or more, 12 hours or more, 13 hours or more, or 14 hours or more, and 15 hours or less, 16 hours or less, 17 hours or less, or 18 hours or less. When the above-mentioned calcination time is within the above-mentioned range, the crystallinity of the lithium composite transition metal oxide particles is sufficiently controlled, which is advantageous for lithium ion transport.

[0135]

[0136] (B) Step

[0137] The method for manufacturing a positive electrode active material according to the present invention includes, after step (A), a step of mixing the lithium composite transition metal oxide and a raw material containing a coating element (M) and then performing heat treatment to form a coating layer.

[0138]

[0139] The above coating element (M) is at least one selected from Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si. By forming a coating layer containing the coating element (M) on the lithium composite transition metal oxide, electrical conductivity can be improved and by-products formed by a side reaction with the electrolyte can be controlled, thereby improving the capacity characteristics, resistance characteristics, and life characteristics of the positive electrode active material. On the other hand, when a coating layer containing the coating element (M) is not formed on the lithium composite transition metal oxide, there is a problem that the electrical conductivity is inferior and the capacity characteristics, resistance characteristics, and life characteristics are inferior due to by-products formed by a side reaction with the electrolyte.

[0140]

[0141] According to one embodiment of the present invention, the raw material containing the coating element (M) may use at least one selected from oxides, carbonates, nitrates, hydroxides, oxyhydroxides, and halides containing the coating element (M). Specifically, in order to exhibit the effect of suppressing the generation of byproducts in the form of hydrogen fluoride and exhibiting high capacity characteristics at a high rate, an oxide containing the coating element (M) may be used, and the coating element (M) may be Al or W.

[0142]

[0143] According to one embodiment of the present invention, the raw material containing the coating element (M) may be mixed so that the coating element (M) content is 3,000 ppm or more and 5,500 ppm or less with respect to the total weight of the lithium composite transition metal oxide. Specifically, the coating element (M) is 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, 5,100 ppm or less, It may be mixed so that the content is 5,200 ppm or less, 5,300 ppm or less, 5,400 ppm or less, or 5,500 ppm or less. When the mixing amount of the raw material containing the coating element (M) is within the above range, the electrical conductivity 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 positive electrode active material.

[0144]

[0145] 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.

[0146]

[0147] According to one embodiment of the present invention, the heat treatment may be performed at a temperature of 400°C or higher and 600°C or lower. 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 thermal energy required for coating can be supplied. When the above lithium composite transition metal oxide and the coating (M) raw material are mixed and then heat-treated in the above temperature range, a coating layer including a coating element (M) can be formed on the lithium composite transition metal oxide. The coating layer including the coating element (M) can be in the form of partially covering (discontinuously) at least a portion of the lithium composite transition metal oxide, i.e., a region of the lithium composite transition metal oxide, or covering (continuously) the entire region. The form of the coating layer can be a film type, an island type, or a combination thereof.

[0148]

[0149] The above heat treatment may be performed for 3 hours or more and 9 hours or less. Specifically, the heat treatment may be performed for 3 hours or more, 4 hours or more, or 5 hours or more, and 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.

[0150]

[0151] anode

[0152] Next, the anode according to the present invention will be described.

[0153]

[0154] The positive electrode according to the present invention comprises a positive electrode active material layer comprising the positive electrode active material according to the present invention. Specifically, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and comprising the positive electrode active material. Since the positive electrode active material has been described above, a detailed description thereof will be omitted, and only the remaining components will be described in detail below.

[0155]

[0156] The positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 µm to 500 µm, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesive strength of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0157]

[0158] The above-mentioned positive electrode active material layer may include a conductive material and a binder together with the positive electrode active material. At this time, 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 characteristics may be exhibited within this range.

[0159]

[0160] 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, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; 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 type alone or a mixture of two or more types of these 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.

[0161]

[0162] The above binder serves to improve the adhesion between positive electrode active material particles and the adhesive strength between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The 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.

[0163]

[0164] 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 coating 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 and a conductive material in a solvent, on a positive electrode current collector, followed by drying and rolling. At this time, the types and contents of the positive electrode active material, binder, and conductive material are as described above. Alternatively, the positive electrode can be manufactured by casting the composition for forming a positive electrode active material layer on a separate support, and then laminating the film obtained by peeling it from the support on a positive electrode current collector.

[0165]

[0166] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), 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, and binder, taking into account 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.

[0167]

[0168] lithium secondary battery

[0169] Next, a lithium secondary battery according to the present invention will be described.

[0170]

[0171] The present invention can manufacture an electrochemical device including the above-described positive electrode. The electrochemical device may be, specifically, a battery, a capacitor, or the like, and more specifically, a lithium secondary battery.

[0172]

[0173] The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, and a separator and electrolyte interposed between the positive electrode and the negative electrode. Since the positive electrode is the same as described above, a detailed description thereof will be omitted, and only the remaining components will be described in detail below.

[0174]

[0175] In addition, the lithium secondary battery may optionally further include a battery container that houses the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0176]

[0177] In the above lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0178] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and 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.

[0179]

[0180] The above negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0181]

[0182] 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 fiber-like forms, 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.

[0183] The above negative electrode active material may be included in an amount of 80% to 99% by weight based on the total weight of the negative electrode active material layer.

[0184]

[0185] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and can typically be 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, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0186]

[0187] The conductive agent 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, specifically, 5 wt% or less, based on the total weight of the negative electrode active material layer. The conductive agent is not particularly limited as long as it has conductivity and does not cause 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; metal powders such as fluorocarbon, aluminum, and 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.

[0188]

[0189] The negative electrode active material layer may 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.

[0190]

[0191] Meanwhile, in the lithium secondary battery, the 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 special 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, can 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. can also be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength can be used, and can optionally be used in a single-layer or multi-layer structure.

[0192]

[0193] In addition, examples of the electrolyte used in the present invention 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.

[0194] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0195] 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), ethylene carbonate (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.In this case, the performance of the electrolyte may be improved when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0196]

[0197] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, 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. The concentration of the lithium salt is preferably used within the range of 0.1 to 5.0 M, specifically, 0.1 to 3.0 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.

[0198]

[0199] 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 life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additive may be included in an amount of 0.1 to 10 wt%, specifically, 0.1 to 5 wt%, based on the total weight of the electrolyte.

[0200]

[0201] As described above, a lithium secondary battery including a cathode active material according to the present invention exhibits excellent life characteristics and capacity characteristics, and is therefore useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0202] Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0203] 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.

[0204] 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.

[0205] 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.

[0206]

[0207]

[0208] 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.

[0209]

[0210] Examples and Comparative Examples

[0211] Example 1

[0212] Ni 0.62 Co 0.06 Mn 0.32 A complex transition metal hydroxide having a composition represented by (OH)2 (product name: Nickel cobalt manganese hydroxide, D 50 : 3.5㎛, BET: 15m 2 / g, secondary particles) and Li2CO3 were added so that the molar ratio of (Ni+Co+Mn):Li was 1:1.05, and Y2O3 was added to Ni 0.62 Co 0.06 Mn 0.32 ZrO2 is added to Ni so that the content of Y is 1,500 ppm with respect to the total weight of (OH)2. 0.62 Co 0.06 Mn 0.32 (OH)2 was added and mixed so that Zr content was 3,000 ppm with respect to the total weight, and then calcined at 940℃ for 14 hours in an air atmosphere to obtain LiNi 0.625 Co 0.06 Mn 0.311 Zr 0.003 Y 0.001 A lithium composite transition metal oxide having a composition represented by O2 was prepared.

[0213] The lithium composite transition metal oxide, Al2O3 and WO3 were mixed and heat-treated at 500°C for 5 to 7 hours in an air atmosphere to produce a positive electrode active material in which a coating layer including Al and W was formed on the lithium composite transition metal oxide. At this time, the Al2O3 was LiNi 0.625 Co 0.06 Mn 0.311 Zr 0.003 Y 0.001 Mix Al so that the content is 1,500 ppm with respect to the total weight of O2. , WO3 is the above LiNi 0.625 Co 0.06 Mn 0.311 Zr0.003 Y 0.001 W was mixed so that the content was 3,000 ppm with respect to the total weight of O2. The coating layer includes a Li-Al-O compound, a Li-WO compound, and a Li-Al-WO compound.

[0214]

[0215] Example 2

[0216] Ni 0.62 Co 0.06 Mn 0.32 Instead of complex transition metal hydroxides having a composition represented by (OH)2, Ni 0.65 Co 0.05 Mn 0.30 (OH)2(Product name: Nickel cobalt manganese hydroxide, D 50 : 3.5㎛, BET: 15m 2 A positive electrode active material was prepared in the same manner as in Example 1, except that a composite transition metal hydroxide having a composition represented by / g, secondary particles was used.

[0217]

[0218] Comparative Example 1

[0219] Ni 0.62 Co 0.06 Mn 0.32 Instead of complex transition metal hydroxides having a composition represented by (OH)2, Ni 0.60 Co 0.05 Mn 0.35 (OH)2(Product name: Nickel cobalt manganese hydroxide, D 50 : 3.5㎛, BET: 15m 2 A positive electrode active material was prepared in the same manner as in Example 1, except that a composite transition metal hydroxide having a composition represented by / g, secondary particles was used.

[0220]

[0221] Comparative Example 2

[0222] The lithium composite transition metal oxide of Example 1 was used as the positive electrode active material of Comparative Example 2.

[0223]

[0224] Comparative Example 3

[0225] Ni 0.62 Co 0.06 Mn 0.32 Instead of complex transition metal hydroxides having a composition represented by (OH)2, Ni 0.685 Co 0.095 Mn 0.220 (OH)2(Product name: Nickel cobalt manganese hydroxide, D 50 : 3.5㎛, BET: 15m 2 A positive electrode active material was prepared in the same manner as in Example 1, except that a composite transition metal hydroxide having a composition represented by / g, secondary particles was used.

[0226]

[0227] Experimental example

[0228] Experimental Example 1: Analysis of Lithium Complex Transition Metal Oxides

[0229] - Composition of lithium complex transition metal oxide

[0230] For the lithium composite transition metal oxides manufactured in the above examples and comparative examples, the composition of the lithium composite transition metal oxides was confirmed by the following method, and is shown in Table 1 below.

[0231] 1 ml of hydrochloric acid was added to 0.1 g of each of the lithium composite transition metal oxide particles manufactured in the above examples and comparative examples, and heated to dissolve the lithium composite transition metal oxide. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction, completely dissolving the lithium composite transition metal oxide to prepare a solution. Subsequently, the solution was diluted with deionized water to a total volume of 10 ml to prepare an analysis sample. Using ICP-OES (Optima 7300DV, Perkin Elmer), the composition of the lithium composite transition metal oxide present in the analysis sample was confirmed, and the composition of the lithium composite transition metal oxide and the difference (ac) in the mole fraction of nickel and the mole fraction of manganese are shown in Table 1 below.

[0232] Composition AC Example 1Li 1.032 Ni 0.624 Co 0.06 Mn 0.312 Zr 0.003 Y 0.001 O20.312 Example 2Li 1.035 Ni 0.643 Co 0.051 Mn 0.302 Zr 0.003 Y 0.001 O20.341 Comparative Example 1Li 1.030 Ni 0.598 Co 0.05 Mn 0.348 Zr 0.003 Y 0.001 O20.25 Comparative Example 2Li 1.028 Ni 0.624 Co 0.06 Mn 0.312 Zr 0.003 Y 0.001 O20.312 Comparative Example 3Li 1.027 Ni 0.680 Co 0.097 Mn 0.219 Zr 0.003 Y 0.001 O20.463

[0233] Through Table 1, it was confirmed that the lithium composite transition metal oxides manufactured in Examples 1 and 2 had a composition represented by Chemical Formula 1 described herein. In addition, it was confirmed that the lithium composite transition metal oxides manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 had a difference in the mole fractions of nickel and manganese, that is, the difference (ac) between the mole fraction a of nickel (Ni) among all metals excluding lithium in the lithium composite transition metal oxide in the composition represented by Chemical Formula 1 described herein and the mole fraction c of manganese (Mn) among all metals excluding lithium in the lithium composite transition metal oxide was 0.25 or more and 0.45 or less. On the other hand, it was confirmed that the lithium composite transition metal oxide manufactured in Comparative Example 3 had an ac greater than 0.45.

[0234]

[0235] Experimental Example 2: Analysis of positive electrode active material

[0236] - Content of coating element (M) included in the coating layer

[0237] For the positive electrode active materials manufactured in the above examples and comparative examples, the contents of aluminum (Al) and tungsten (W) included in the coating layer were confirmed by the following method, and are shown in Table 2 below.

[0238] To each 0.1 g of the positive electrode active material particles manufactured in the above examples and comparative examples, 1 ml of hydrochloric acid was added, and the mixture was heated to dissolve the positive electrode active material. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction, completely dissolving the positive electrode active material to prepare a solution. Subsequently, the solution was diluted with deionized water to a total volume of 10 ml to prepare an analysis sample. Using ICP-OES (Optima 7300DV, Perkin Elmer), the contents (ppm) of aluminum (Al) and tungsten (W) included in the positive electrode active material coating layer present in the analysis sample were confirmed, and the results are shown in Table 2 below.

[0239] Content (ppm) Aluminum (Al) Tungsten (W) Example 11,1202,050 Example 21,1802,090 Comparative Example 11,2302,240 Comparative Example 2--Comparative Example 31,1502,110

[0240] Through Table 2, it was confirmed that the total content of aluminum and tungsten, which are coating elements included in the positive electrode active material coating layer manufactured in Examples 1 and 2, was 3,000 ppm or more and 5,500 ppm or less with respect to the total weight of the lithium composite transition metal oxide.

[0241] - Particle size and particle size distribution of positive electrode active material

[0242] Using PSA (S3500, Microtrac), the average particle diameter (D) of the positive electrode active materials manufactured in the examples and comparative examples 50 ) were measured and shown in Table 3 below.

[0243] In addition, using SEM (FEI, Inspect F), SEM images (5K magnification) of the positive electrode active materials manufactured in the examples and comparative examples were obtained, and using an image processing program (LG Chemical, DX program), the boundaries of the primary particles existing in the SEM images were divided and images were displayed in random colors. Using the images in which the boundaries of the primary particles were divided and displayed in random colors, the area of ​​each primary particle was calculated through the number of pixels corresponding to each of n primary particles (an average of 50,000 or more primary particles), and the average particle diameter (D') of the primary particles existing in the lithium composite transition metal oxide manufactured in Example 1 was used, which is the diameter of a circle having the same area as the area of ​​each primary particle. 50 ) was measured and shown in Table 3 below. And, the average particle diameter (D) of lithium composite transition metal oxide 50 ) for the average particle diameter (D') of the primary particles 50 ) was calculated (the degree of single particle magnetization (χ)) and is shown in Table 3 below.

[0244] Average particle size (㎛) Single particle magnetization (χ) Primary particle (D')50 )Cathode active material (D 50 ) Example 12.494.020.62 Example 23.423.890.88 Comparative Example 11.584.340.36 Comparative Example 22.494.020.62 Comparative Example 33.734.040.92

[0245] Through Table 3, the primary particles of the positive electrode active materials manufactured in Examples 1 and 2 have an average particle diameter (D') 50 ) was confirmed to be 2㎛ or more and 5㎛ or less, and the average particle diameter (D) of the positive electrode active material 50 ) was confirmed to be 3㎛ or more and 5㎛ or less. In addition, it was confirmed that the positive electrode active materials manufactured in Examples 1 and 2 had a single particle size (χ) of more than 0.5 according to Equation 1 described herein. For reference, it can be seen that the positive electrode active materials manufactured in Examples 1 and 2 had a single particle size of 0.6 or more and 0.9 or less, indicating that they were single particle forms with suppressed agglomeration between primary particles. On the other hand, it was confirmed that the positive electrode active material manufactured in Comparative Example 1 had a single particle size of 0.5 or less according to Equation 1 described herein.

[0246] Meanwhile, the average particle diameter (D') of the primary particles of the positive electrode active material manufactured in Example 1 including a coating layer and the positive electrode active material manufactured in Comparative Example 2 not including a coating layer 50 ) and the average particle diameter (D) of the positive electrode active material 50 ) It can be seen that the coating layer is formed in nano units from these being almost identical.

[0247]

[0248] - Shape of positive electrode active material and coating layer

[0249] For the positive electrode active materials manufactured in the above examples and comparative examples, SEM images taken at 5K magnification were obtained using a scanning electron microscope (SEM), and the SEM images of the positive electrode active materials manufactured in Examples 1 and 2 and Comparative Examples 1 and 3 are shown in FIGS. 1 to 4. In addition, SEM images taken at 20K magnification and 50K magnification for the positive electrode active material manufactured in Example 1 were obtained, and these are shown in FIGS. 5 and 6, respectively.

[0250] Figure 1 is a SEM image (5K magnification) of the positive electrode active material manufactured in Example 1.

[0251] Figure 2 is a SEM image (5K magnification) of the positive electrode active material manufactured in Example 2.

[0252] Figure 3 is a SEM image (5K magnification) of the positive electrode active material manufactured in Comparative Example 1.

[0253] Figure 4 is a SEM image (5K magnification) of the positive electrode active material manufactured in Comparative Example 3.

[0254] Figure 5 is a SEM image (20K magnification) of the positive electrode active material manufactured in Example 1.

[0255] Figure 6 is a SEM image (50K magnification) of the positive electrode active material manufactured in Example 1.

[0256] Through Figures 1 to 4, it was confirmed that the positive electrode active materials manufactured in Examples 1 and 2 according to the present invention were in the form of single particles. The positive electrode active materials are composed of a coating layer on a lithium composite transition metal and a lithium composite transition metal oxide, and since it was confirmed in the experimental examples above that the coating layer was formed in nano-units, it can be confirmed that the lithium composite transition metal oxides manufactured in Examples 1 and 2 are in the form of single particles. In addition, it was confirmed that the positive electrode active materials manufactured in Examples 1 and 2 had less fine particles and larger particle sizes compared to the positive electrode active material manufactured in Comparative Example 1.

[0257] Through FIGS. 5 and 6, it was confirmed that the positive electrode active material manufactured in Example 1 according to the present invention includes a coating layer including a coating element in an island type on the positive electrode active material.

[0258] In conclusion, the positive electrode active materials manufactured in Examples 1 and 2 had an average particle diameter (D') of primary particles 50 ) was confirmed to be larger than the positive electrode active material manufactured in Comparative Example 1, and it was confirmed that the coating layer including the coating element (M) partially covers at least a portion of the lithium composite transition metal oxide.

[0259]

[0260] Experimental Example 3: Battery Characteristics Evaluation

[0261] - Manufacturing of coin-type half-cells

[0262] A positive electrode slurry was prepared by mixing 95 wt% of the positive electrode active material manufactured in the above examples and comparative examples, 2.0 wt% of Super P as a conductive agent, and 3.0 wt% of polyvinylidene fluoride (PVDF) as a binder in an N-methylpyrrolidone (NMP) solvent. The prepared positive electrode slurry was applied to one surface of an aluminum current collector, dried at 130°C, and then rolled to prepare a positive electrode.

[0263] An electrode assembly was manufactured using a lithium metal electrode as the negative electrode and a porous polyethylene separator interposed between the positive and negative electrodes. This was placed inside a battery case, and a coin-type half-cell was manufactured by injecting an electrolyte solution containing 1 M LiPF6 dissolved in an organic solvent containing ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) in a volume ratio of 3:4:3.

[0264]

[0265] - Evaluation of battery capacity characteristics and cycle characteristics

[0266] Using the coin-type half-cell manufactured as described above, the activation process (formation) was performed by charging (0.1C) in the CC-CV manner to 4.45 V at 25°C and then discharging (0.1C) in the CC manner to 2.5 V.

[0267] After charging (0.33C) to 4.45 V at 45°C in the CC-CV manner, and then discharging (0.33C) to 2.5 V in the CC manner, one cycle was defined as a cycle, and a total of 100 cycles of charging and discharging were repeated. After measuring the discharge capacity in the first and 100th cycles, the percentage of the discharge capacity in the 100th cycle to the discharge capacity in the first cycle (capacity retention rate (%)) is shown in Table 4 below.

[0268] In addition, after measuring the DC internal resistance (DCIR) of the first cycle and the DCIR of the 100th cycle, the percentage (resistance increase rate (%)) of the DCIR value of the 100th cycle to the measured DCIR value of the first cycle was calculated and shown in Table 4 below. The DCIR value is a value calculated by dividing the difference between the voltage at 60 seconds and the initial voltage while discharging with a constant current of 0.33 C in each cycle by the applied current.

[0269] After charging (0.1C) to 4.45 V at 25°C using the CC-CV method, the initial charge-discharge process was performed by discharging (0.1C) to 2.5 V using the CC method, and the charge and discharge capacities at this time were measured. The measured charge and discharge capacities and the percentage of discharge capacity to charge capacity (efficiency (%)) are shown in Table 4 below.

[0270] @45℃, 0.33C@45℃, 0.33C@25℃, 0.1CDischarge capacity (mAh / g)Capacity retention rate (%)Direct current internal resistance (DCIR)Resistance increase rate (%)Charge capacity (mAh / g)Discharge capacity (mAh / g)Efficiency (%)First cycle100th cycleFirst cycle100th cycleExample 1186.0168.889.51.503.20113.5222.4201.490.6Example 2184.6168.291.11.613.59122.7221.4199.890.2Comparative example 1190.4169.589.01.463.54142.3224.2203.190.6Comparative example 2183.4161.488.01.684.41162.4221.2198.889.8Comparative example 3187.2171.391.52.245.45143.3224.0200.689.6

[0271] As shown in Table 4, the battery including the positive electrode active material manufactured in Comparative Example 1 having a particle size distribution of 0.5 or less according to Equation 1 described herein has a high discharge capacity in the first and 100th cycles at high temperature, and a high charge / discharge capacity and efficiency at room temperature, but has problems of low capacity retention and high resistance increase rate at high temperature. On the other hand, the battery including the positive electrode active material manufactured in Comparative Example 2, which does not include a coating layer on a lithium composite transition metal oxide, has problems of low discharge capacity, capacity retention, and efficiency in the first and 100th cycles at high temperature, a high resistance increase rate, and low charge / discharge capacity and efficiency at room temperature.

[0272] In addition, a battery including a cathode active material manufactured in Comparative Example 3, in which the lithium composite transition metal oxide does not have a composition represented by the chemical formula 1 described herein, specifically, ac is greater than 0.45, has high charge / discharge capacity and capacity retention rate at high temperatures, but has problems of high high-temperature DC internal resistance and high resistance increase rate, and low charge / discharge efficiency at room temperature.

[0273] In comparison, it was confirmed that the batteries including the positive electrode active materials manufactured in Examples 1 and 2 having a single particle size distribution of more than 0.5 according to Formula 1 described herein maintained the charge / discharge capacity at high temperatures and the charge / discharge capacity and efficiency at room temperature at the same level as the battery including the positive electrode active material manufactured in Comparative Example 1, but had superior capacity retention rate and resistance increase rate at high temperatures. In addition, it was confirmed that the batteries including the positive electrode active materials manufactured in Examples 1 and 2 having a composition represented by Chemical Formula 1 described herein maintained the capacity retention rate at high temperatures at a similar level as the battery manufactured in Comparative Example 3, but had superior resistance and resistance increase rate at high temperatures and superior charge / discharge efficiency at room temperature.

[0274] In conclusion, it can be confirmed that the positive electrode active material according to the present invention maintains charge / discharge capacity and efficiency at the same level at high temperature and room temperature, while having excellent DC internal resistance and resistance increase rate at high temperature. Through this, it can be seen that the positive electrode active material according to the present invention maintains energy density and is stable with little structural change even during charge / discharge cycles.

Claims

A lithium composite transition metal oxide having a single particle form composed of 1.10 or fewer primary particles and having a composition represented by the following chemical formula 1; and A coating layer including a coating element (M) formed on the lithium composite transition metal oxide; The above coating element (M) is at least one selected from Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn and Si, A cathode active material having a single particle magnetization degree (χ) greater than 0.5 according to the following formula 1: [Chemical Formula 1] Li 1+x Ni a Co b Mr c M 1 d O2 In the above chemical formula 1, Above M 1 is at least one selected from Zr, Y, W, Cu, Sr, Mn, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al, -0.1≤x≤0.1, 0.6≤a<1, 0 <b<0.4, 0<c<0.4, 0≤d≤0.1, a+b+c+d=1, 0.25≤a-c≤0.45이고, [Formula 1] .

2. In claim 1, A positive electrode active material in the above chemical formula 1, wherein a is 0.6 or more and 0.75 or less.

3. In claim 1, In the above chemical formula 1, the ac is 0.25 <a-c<0.34인 것인 양극 활물질.

4. In claim 1, A positive electrode active material having a content of a coating element (M) included in the coating layer of 3,000 ppm or more and 5,500 ppm or less based on the total weight of the lithium composite transition metal oxide.

5. In claim 1, The above coating layer comprises a Li-MO compound, The positive electrode active material wherein the above M is at least one selected from Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn and Si.

6. In claim 1, A positive electrode active material wherein the above coating element (M) is at least one selected from Al and W.

7. In claim 1, The average particle diameter (D') of the above primary particles 50 ) is a positive electrode active material having a size of 2㎛ or more and 5㎛ or less.

8. In claim 1, The average particle diameter (D) of the above positive electrode active material 50 ) is a positive electrode active material having a size of 3㎛ or more and 5㎛ or less.

9. In claim 1, A cathode active material having a single particle magnetization (χ) of 0.6 or more and 0.9 or less. 10.(A) A step of mixing and calcining a composite transition metal hydroxide and a lithium (Li)-containing raw material to produce a lithium composite transition metal oxide; and (B) a step of forming a coating layer by mixing the lithium composite transition metal oxide and the raw material containing the coating element (M) and then performing heat treatment; The above firing is performed at a temperature of 800℃ or higher and 1,100℃ or lower. A method for manufacturing a positive electrode active material according to claim 1, wherein the coating element (M) is at least one selected from Al, W, Cu, Zr, Ni, Co, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, and Si.

11. In claim 10, A method for producing a positive electrode active material, wherein the raw material containing the coating element (M) is at least one selected from oxides, carbonates, nitrates, hydroxides, oxyhydroxides, and halides containing the coating element (M).

12. In claim 10, A method for manufacturing a positive electrode active material, wherein the raw material containing the above coating element (M) is mixed so that the coating element (M) content is 3,000 ppm or more and 5,500 ppm or less with respect to the total weight of the above lithium composite transition metal oxide.

13. In claim 10, A method for manufacturing a positive electrode active material, wherein the above heat treatment is performed at a temperature of 400°C or higher and 600°C or lower.

14. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 9.

15. A lithium secondary battery comprising a positive electrode according to claim 14.

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