Positive electrode active material, and positive electrode and lithium secondary battery which include the same

Abstract

The present invention relates to a positive electrode active material, which includes a lithium composite transition metal oxide having a composition represented by Formula 1 described in this specification, wherein the lithium composite transition metal oxide is in a form of a single particle, and has a degree of single crystal formation (χ) according to Equation 1 described in this specification of 0.0500 to 0.0750, and a positive electrode and a lithium secondary battery which include the same.

Description

Cathode active material and cathode and lithium secondary battery containing the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0034208, filed March 12, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a cathode active material and a cathode and 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 secondary batteries are composed of four major components: a cathode, an anode, a separator, and an electrolyte. Among these, the cathode active material contained in the cathode plays a significant role in determining the battery's capacity, output, and lifespan. For lithium secondary batteries to achieve high energy density, output, and lifespan, improving the performance of the cathode active material is essential. Consequently, extensive research has been conducted recently to develop high-performance cathode active materials.

[0008] Lithium transition 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.

[0009] 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.

[0010] 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.

[0011] Meanwhile, in the case of lithium composite transition metal oxides with high nickel content, the average particle size (D 50 ) is a secondary particle form in which primary particles having agglomeration are formed, and has a large specific surface area and low particle strength. Therefore, when an electrode is manufactured with a positive electrode active material including secondary particles in which the primary particles are agglomerated and then rolled, there is a problem in that the particle breakage is severe, and when the cell is operated, a large amount of gas is generated, resulting in poor stability and lifespan characteristics.

[0012] 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.

[0013]

[0014] [Prior Art Literature]

[0015] [Patent Document]

[0016] (Patent Document 1) Korean Patent Publication No. 10-2023-0013396

[0017]

[0018] The present invention is intended to solve the above problems and to provide a positive electrode active material capable of improving the capacity and life characteristics of a battery.

[0019] 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.

[0020]

[0021] (1) The present invention provides a positive electrode active material comprising a lithium composite transition metal oxide having a composition represented by the following chemical formula 1, wherein the lithium composite transition metal oxide is in the form of a single particle, and the lithium composite transition metal oxide has a single crystallinity (χ) of 0.0500 or more and 0.0750 or less according to the following chemical formula 1.

[0022] [Chemical Formula 1]

[0023] Li 1+x Ni a Mn b Co c Al d M 1 e M 2 f O2

[0024] In the above chemical formula 1, M 1 is at least one selected from the group consisting of Zr, K, Sr and Ba, and M 2 is at least one selected from the group consisting of B, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo and W, and 0.00≤x≤0.10, 0.600≤a<1.000, 0.000 <b<0.400, 0.000<c<0.400, 0.000<d≤0.100, 0.000<e≤0.100, 0.000≤f≤0.010이고,

[0025] [Formula 1]

[0026] am.

[0027] (2) The present invention provides a positive electrode active material having a single crystallinity (χ) of 0.0550 or more and 0.0700 or less in the above (1).

[0028] (3) The present invention, in the above (1) or (2), the M 1 Provided is a cathode active material comprising at least one selected from the group consisting of Zr, Sr, and Ba.

[0029] (4) The present invention is characterized in that in any one of the above (1) to (3), M in the lithium composite transition metal oxide 1 A positive electrode active material is provided, the content of which is 500 ppm or more and 4,000 ppm or less based on the total weight of the lithium composite transition metal oxide.

[0030] (5) The present invention provides a positive electrode active material in any one of the above (1) to (4), wherein the lithium composite transition metal oxide has an average crystallite size (α) of 170.0 nm or more and 300.0 nm or less.

[0031] (6) In any one of (1) to (5), the lithium composite transition metal oxide has an average particle diameter (D 50 ) provides a positive electrode active material having a diameter of 3.00㎛ or more and 5.00㎛ or less.

[0032] (7) The present invention provides a positive electrode comprising a positive electrode active material according to any one of (1) to (6).

[0033] (8) The present invention provides a lithium secondary battery including a positive electrode according to (7) above.

[0034]

[0035] The cathode active material according to the present invention has a composition represented by the chemical formula 1 described herein, is in the form of a single particle, and includes a lithium composite transition metal oxide having a single crystallinity within a specific range, so that the capacity and life characteristics can be improved.

[0036] Accordingly, the performance, particularly the capacity and life characteristics, of the positive electrode and secondary battery including the positive electrode active material can be improved.

[0037]

[0038] Figure 1 is a SEM image of the positive electrode active material manufactured in Example 1.

[0039] Figure 2 is a SEM image of the positive electrode active material manufactured in Example 2.

[0040] Figure 3 is a SEM image of the positive electrode active material manufactured in Example 3.

[0041] Figure 4 is an SEM image of the positive electrode active material manufactured in Example 4.

[0042] Figure 5 is an SEM image of the positive electrode active material manufactured in Example 5.

[0043] Figure 6 is an SEM image of the positive electrode active material manufactured in Example 6.

[0044] Figure 7 is an SEM image of the positive electrode active material manufactured in Comparative Example 1.

[0045] Figure 8 is an SEM image of the positive electrode active material manufactured in Comparative Example 2.

[0046] Figure 9 is an SEM image of the positive electrode active material manufactured in Comparative Example 3.

[0047] Figure 10 is an SEM image of the positive electrode active material manufactured in Comparative Example 4.

[0048] Figure 11 is an SEM image of the positive electrode active material manufactured in Comparative Example 5.

[0049] Figure 12 is a graph of capacity retention rate (cycle retention (%)) according to cycle of batteries including positive electrode active materials of examples and comparative examples.

[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 "single particle form" refers to a form composed of 30 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 30 primary particles are agglomerated.

[0055] 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.

[0056] In this specification, 'single crystal' means a crystal that does not contain grain boundaries inside the particles.

[0057] In this specification, 'crystallite' means a particle unit having substantially the same crystal orientation.

[0058] In this specification, the 'average crystallite size (α)' can be quantitatively analyzed using X-ray diffraction analysis (XRD) using Cu Kα X-rays. Specifically, the average crystallite size of the crystal grains can be quantitatively analyzed by putting the particles to be measured into a holder, irradiating the particles with X-rays, and analyzing the diffraction grating that is generated. Sampling was prepared by putting the powder sample of the particles to be measured into the groove in the center of a general powder holder, smoothing the surface using a slide glass, and ensuring that the sample height is the same as the edge of the holder. Then, X-ray diffraction analysis was performed using a Bruker D4 Endeavor (light source: Cu-Kα rays, wavelength: 1.54 Å) equipped with a LynxEye XE-T position sensitive detector, under the conditions of FDS 0.5°, 2θ=15° to 80°, step size 0.02°, and total scan time of approximately 20 minutes. For the measured data, Rietveld refinement was performed considering the charge (+3 for metal ions at transition metal sites, +2 for Ni ions at Li sites) and cation mixing at each site. When analyzing the crystallite size, instrumental brodadening was considered using the Fundamental Parameter Approach (FPA) implemented in the Bruker TOPAS program, and the entire peaks of the measurement range were used for fitting. The peak shape was fitted using only the Lorenzian contribution as the First Principle (FP) among the peak types available in TOPAS, and strain was not considered at this time.

[0059] 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).

[0060] In this specification, the average particle diameter (D) of the lithium composite transition metal oxide 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 of the lithium composite transition metal oxide can be measured by dispersing the powder to be measured in a dispersion medium, introducing it into a commercially available laser diffraction particle size measuring device (e.g., S3500 from Microtrac), 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 the particle size in the measuring device.

[0061]

[0062] positive electrode active material

[0063] Hereinafter, the positive electrode active material according to the present invention will be described.

[0064]

[0065] The cathode active material according to the present invention includes a lithium composite transition metal oxide having a composition represented by the following chemical formula 1, wherein the lithium composite transition metal oxide is in the form of a single particle, and the lithium composite transition metal oxide has a single crystallinity (χ) according to the following chemical formula 1 of 0.0500 or more and 0.0750 or less.

[0066] [Chemical Formula 1]

[0067] Li 1+x Ni a Mn b Co c Al d M 1 eM 2 f O2

[0068] In the above chemical formula 1, M 1 is at least one selected from the group consisting of Zr, K, Sr and Ba, and M 2 is at least one selected from the group consisting of B, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo and W, and 0.00≤x≤0.10, 0.600≤a<1.000, 0.000 <b<0.400, 0.000<c<0.400, 0.000<d≤0.100, 0.000<e≤0.100, 0.000≤f≤0.010이고,

[0069] [Formula 1]

[0070] am.

[0071]

[0072] Meanwhile, if the lithium composite transition metal oxide does not have a composition represented by the chemical formula 1 described herein, is not in the form of a single particle, and has a single crystallinity of less than 0.0500 according to the chemical formula 1 described herein, there is a problem of poor capacity characteristics and a problem of fine particles being generated due to particle breakage when rolling the positive electrode active material for electrode production, and when this is applied to a battery, there is a problem of gas being generated, which reduces the life characteristics of the battery.

[0073]

[0074] The present inventors have found that, in the case of a positive electrode active material comprising a lithium composite transition metal oxide having a composition represented by the chemical formula 1 described herein, in the form of single particles, and having a degree of single crystallinity of 0.0500 or more and 0.0750 or less according to the chemical formula 1 described herein, the thermal stability can be improved while improving the capacity characteristics by controlling the area of ​​the grain boundary, particle breakage can be suppressed when the positive electrode active material is rolled for electrode manufacture, and when applied to a battery, unnecessary side reactions with an electrolyte and the amount of gas generated can be improved, and thus the present invention has been completed. As described above, a battery using the positive electrode active material according to the present invention can have excellent capacity characteristics and life characteristics.

[0075]

[0076] The above lithium composite transition metal oxide has a composition represented by the following chemical formula 1.

[0077] [Chemical Formula 1]

[0078] Li 1+x Ni a Mn b Co c Al d M 1 e M 2 f O2

[0079] In the above chemical formula 1,

[0080] M 1 is at least one selected from the group consisting of Zr, K, Sr and Ba,

[0081] M 2 is at least one selected from the group consisting of B, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo and W,

[0082] 0.00≤x≤0.10, 0.600≤a<1.000, 0.000 <b<0.400, 0.000<c<0.400, 0.000<d≤0.100, 0.000<e≤0.100, 0.000≤f≤0.010이고,

[0083] Above M 1 is a doping element, specifically the above M 1 is at least one selected from the group consisting of Zr, K, Sr and Ba. The above M 1 is essentially included, which can improve capacity characteristics and life characteristics. In particular, M 1 When at least one selected from the group consisting of Zr, Sr and Ba is present, the structural stability of the positive electrode active material can be improved, the life characteristics can be improved, and the crystal growth can be assisted to increase the single crystallinity. Meanwhile, M 1 In this case, there is a problem that the average crystallite size of the lithium composite transition metal oxide becomes excessively large, and the single crystallinity (χ) according to Equation 1 described in the present invention exceeds 0.0750.

[0084] Above M 2 is a doping element, specifically the above M 2 M may be at least one selected from the group consisting of B, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo and W. 2 Although not necessarily included, 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.

[0085] Meanwhile, the above x may be 0.00 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 0.10 or less. When x satisfies the above range, high capacity characteristics and high energy density per unit volume can be realized.

[0086] The above a is the molar ratio of nickel (Ni) among all metals excluding lithium in the lithium composite transition metal oxide, and may be 0.600 or more, 0.650 or more, 0.700 or more, 0.750 or more, 0.800 or more, or 0.850 or more, and may be 0.900 or less, 0.950 or less, or less than 1.000. In particular, when a is 0.800 or more and 0.900 or less, a high energy density is exhibited, so that high-capacity characteristics can be realized.

[0087] The above b is the molar ratio of manganese (Mn) among all metals excluding lithium in the lithium composite transition metal oxide, and may be greater than 0.000, 0.010 or more, 0.020 or more, 0.030 or more, 0.040 or more, or 0.050 or more, and may be 0.060 or less, 0.070 or less, 0.080 or less, 0.090 or less, 0.100 or less, 0.200 or less, 0.300 or less, or less than 0.400. When b satisfies the above range, stability at room temperature and high temperature increases, and decomposition reaction of the electrolyte may be relatively reduced.

[0088] The above c is the molar ratio of cobalt (Co) among all metals excluding lithium in the lithium composite transition metal oxide, and may be greater than 0.000, 0.010 or more, 0.020 or more, 0.030 or more, 0.040 or more, or 0.050 or more, and may be 0.060 or less, 0.070 or less, 0.080 or less, 0.090 or less, 0.100 or less, 0.200 or less, 0.300 or less, or less than 0.400. When c satisfies the above range, stability can be improved during the charge / discharge process, and rate characteristics at room temperature and high temperature can be enhanced.

[0089] The above d is a molar ratio of aluminum (Al) among all metals excluding lithium in the lithium composite transition metal oxide, and may be greater than 0.000, 0.001 or more, 0.002 or more, 0.003 or more, 0.004 or more, or 0.005 or more, and may be 0.006 or less, 0.007 or less, 0.008 or less, 0.009 or less, 0.010 or less, 0.020 or less, 0.030 or less, 0.040 or less, 0.050 or less, 0.060 or less, 0.070 or less, 0.080 or less, 0.090 or less, or 0.100 or less. When d satisfies the above range, the structural stability of the positive electrode active material can be improved and the output characteristics can be enhanced.

[0090] The above e is M of all metals except lithium in the lithium complex transition metal oxide. 1 The molar ratio of e may be greater than 0.000, greater than 0.001, greater than 0.002, greater than 0.003, greater than 0.004, or greater than 0.005, and may be less than or equal to 0.010, less than or equal to 0.020, less than or equal to 0.030, less than or equal to 0.040, less than or equal to 0.050, less than or equal to 0.060, less than or equal to 0.070, less than or equal to 0.080, less than or equal to 0.090, or less than or equal to 0.100. When e satisfies the above range, it can improve structural stability, reduce gas generation, and improve life characteristics, and can help crystal growth and increase single crystallinity.

[0091] The above f is M among all metals except lithium in the lithium complex transition metal oxide. 2 The molar ratio of f may be 0.000 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, 0.007 or less, 0.008 or less, 0.009 or less, or 0.010 or less. When f 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.

[0092] The above a, b, c, d, e, and f can be a+b+c+d+e+f=1.

[0093]

[0094] The lithium composite transition metal oxide is in the form of a single particle composed of 30 or fewer primary particles. That is, the lithium composite transition metal oxide is in the form of a single particle or a single particle in which 2 or more but 30 or fewer primary particles are aggregated. The single particle form is distinguished from a secondary particle in which more than 30 primary particles are aggregated. When the lithium composite transition metal oxide has a single particle form, it has excellent stability, and even when a positive electrode active material including the same is rolled, the positive electrode active material does not break or crack. As a result, side reactions between the positive electrode active material and the electrolyte can be reduced, and the life characteristics of a battery using the same can be improved.

[0095]

[0096] In the present invention, the degree of single crystallinity is evaluated and expressed as a parameter represented by the above formula 1. The degree of single crystallinity (χ) in the present invention is the average size of crystallites forming one single particle and the average particle diameter (D) of the lithium composite transition metal oxide which is a single particle. 50 ), the average crystallite size (α) within a single particle is the average particle diameter (D) of the lithium composite transition metal oxide. 50 ) the closer it is to the single crystallinity, the higher it appears.

[0097] That is, the degree of single crystallinity shown in the present invention may be higher as the number of crystallites forming a single particle decreases.

[0098] For example, the maximum value of the single crystallinity is 1, which means that one single particle is composed of one crystallite.

[0099] The above lithium composite transition metal oxide has a single crystallinity (χ) of 0.0500 or more and 0.0750 or less according to the following equation 1. In particular, when the single crystallinity (χ) is 0.0550 or more and 0.0700 or less, the grain boundaries, which serve as the migration paths of lithium ions, can be appropriately controlled to improve the capacity characteristics, and when rolling for electrode manufacturing or operating a cell, particle breakage due to grain boundaries can be 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 significantly improving the lifespan of the secondary battery. On the other hand, when the single crystallinity is less than 0.0500, the capacity characteristics are inferior, and when rolling for electrode manufacturing or operating a cell, particle breakage due to grain boundaries occurs, and the grain boundary area in contact with the electrolyte is greatly increased, which increases the amount of gas generation due to side reactions with the electrolyte. When the degree of single crystallinity exceeds 0.0750, there are few crystal grain boundaries that serve as the migration paths of lithium ions within the positive electrode active material particles, so lithium mobility is reduced, and there are problems such as poor resistance characteristics and rate characteristics of the secondary battery.

[0100]

[0101] According to one embodiment of the present invention, M in the lithium composite transition metal oxide 1 The content of may be 500 ppm or more and 4,000 ppm or less based on the total weight of the lithium composite transition metal oxide. Specifically, M in the lithium composite transition metal oxide 1The content of may be 500 ppm or more, 600 ppm or more, 700 ppm or more, 800 ppm or more, 900 ppm or more, 1,000 ppm or more, 1,100 ppm or more, 1,200 ppm or more, or 1,300 ppm or more, and may be 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 ppm or less, or 4,000 ppm or less, based on the total weight of the lithium composite transition metal oxide. The above M 1 When the content is within the above range, structural stability can be improved and life characteristics can be improved.

[0102]

[0103] According to one embodiment of the present invention, the lithium composite transition metal oxide may have an average crystallite size (α) of 170.0 nm or more and 300.0 nm or less. Specifically, the lithium composite transition metal oxide may have an average crystallite size (α) of 170.0 nm or more, 180.0 nm or more, 190.0 nm or more, 200.0 nm or more, or 210.0 nm or more, 270.0 nm or less, 280.0 nm or less, 290.0 nm or less, or 300.0 nm or less. When the average crystallite size (α) is within the above range, particle breakage is suppressed compared to conventional secondary particles in which primary particles are aggregated, and side reactions with the electrolyte and the amount of gas generated are reduced, thereby improving the life characteristics. In addition, it is possible to prevent a decrease in capacity and a decrease in performance due to a decrease in rolling density, and to improve the output characteristics by suppressing an increase in resistance.

[0104]

[0105] According to one embodiment of the present invention, the lithium composite transition metal oxide has an average particle diameter (D50 ) may be 3.00㎛ or more and 5.00㎛ or less. Specifically, the average particle diameter (D of the lithium composite transition metal oxide 50 ) may be 3.00 ㎛ or more, 3.10 ㎛ or more, 3.20 ㎛ or more, 3.30 ㎛ or more, 3.40 ㎛ or more, 3.50 ㎛ or more, 3.60 ㎛ or more, or 3.70 ㎛ or more, and may be 4.20 ㎛ or less, 4.30 ㎛ or less, 4.40 ㎛ or less, 4.50 ㎛ or less, 4.60 ㎛ or less, 4.70 ㎛ or less, 4.80 ㎛ or less, 4.90 ㎛ or less, or 5.00 ㎛ or less. The average particle diameter (D of the lithium composite transition metal oxide 50 ) is within the above range, electrode density can be implemented excellently and capacity characteristics can be improved.

[0106]

[0107] Method for manufacturing positive electrode active material

[0108] The positive electrode active material according to the present invention described above can be manufactured by the following method, but is not limited thereto.

[0109]

[0110] The cathode active material according to the present invention described above comprises (A) a lithium (Li)-containing raw material, a composite transition metal hydroxide, an aluminum (Al)-containing raw material, and M 1 A method for producing a positive electrode active material, comprising the steps of: (A) preparing a mixture by dry mixing of raw materials containing lithium; (B) preparing a plastic product by calcining the mixture at a temperature of 800°C or more and 1,000°C or less; and (C) preparing a lithium composite transition metal oxide by mixing a raw material containing lithium (Li) with the plastic product and calcining the mixture at a temperature of 720°C or more and 900°C or less; wherein, the M 1 is at least one selected from the group consisting of Zr, K, Sr and Ba, and the plasticity is performed for a shorter time than the calcination.

[0111] The positive electrode active material according to the present invention described above can be manufactured by appropriately controlling the type of raw material, mixing ratio, etc.

[0112]

[0113] Hereinafter, each step of the present invention will be described in detail.

[0114]

[0115] (A) Step

[0116] Lithium (Li)-containing raw material, complex transition metal hydroxide, aluminum (Al)-containing raw material and M 1 It includes a step (A) of preparing a mixture by dry mixing of the raw materials contained therein.

[0117]

[0118] The lithium composite transition metal oxide of the present invention utilizes a process of dry mixing solid raw materials, and since no medium is used, energy from the beads is directly transferred to the raw material particles, which is energy efficient, and there is no need for medium filtration or drying, making it simple. On the other hand, if a process of wet mixing a composite transition metal hydroxide and a lithium-containing raw material to prepare a mixture is used, the lithium-containing raw material may dissolve in the solvent rather than react with the composite transition metal hydroxide, and the reaction between the lithium-containing raw material and the composite transition metal hydroxide may not be sufficient, the particle growth may not be smooth, and single particles may not progress sufficiently, and since an over-sintering process is required, it may cause a decrease in capacity during battery use due to reasons such as the formation of a rock-salt phase. In addition, since a precursor-based secondary particle form coexists, the degree of single crystallinity targeted by the present invention cannot be achieved.

[0119]

[0120] Lithium (Li) containing raw materials, aluminum (Al) containing raw materials and M 1In selecting raw materials for the containing raw materials, any raw material applicable to the solid-state synthesis method may be used without limitation. However, since residual sulfur after synthesis may cause problems in the positive electrode active material and sintering equipment, it is preferable to exclude sulfate-based compounds. Specifically, oxide, carbonate, and hydroxide-based compounds may be used. Each raw material and composite transition metal hydroxide may be used in an appropriate amount considering the content of each metal element in the final lithium composite transition metal oxide.

[0121]

[0122] 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.

[0123] The above-mentioned complex transition metal aqueous solution can be prepared by dissolving a transition metal-containing raw material in a solvent such as water. For example, it can be prepared by dissolving a nickel (Ni)-containing raw material, a cobalt (Co)-containing raw material, or a manganese (Mn)-containing raw material in water. In addition, if necessary, the above-mentioned transition metal aqueous solution can further include a metal-containing raw material.

[0124]

[0125] The nickel (Ni)-containing raw material may be 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, and a mixture of one or two or more of these may be used. Specifically, as the nickel-containing raw material, in order to obtain a composite transition metal hydroxide having a uniform composition, water-soluble NiSO 4· 6H2O can be used.

[0126] 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. Specifically, as the cobalt-containing raw material, water-soluble CoSO is used to obtain a complex transition metal hydroxide having a uniform composition. 4· You can use 7H2O.

[0127] The 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 thereof may be used. Specifically, as the manganese-containing raw material, in order to obtain a complex transition metal hydroxide having a uniform composition, water-soluble MnSO 4· You can use H2O.

[0128] 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.

[0129]

[0130] 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.

[0131]

[0132] 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.

[0133]

[0134] When a complex transition metal aqueous 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 through a coprecipitation reaction of the transition metal in the complex transition metal aqueous solution.

[0135] The above coprecipitation reaction can be carried out for 90 hours or more and 120 hours or less. When the coprecipitation reaction is carried out for a time within the above range, the crystallinity of the precursor particles can be controlled to a sufficient degree.

[0136] At this time, the basic compound can be added in an amount such that the pH of the reaction solution becomes within the desired range.

[0137] Once precursor particles are formed as described above, the particles are separated from the reaction solution to obtain a complex transition metal precursor. Specifically, the reaction solution is filtered to separate the complex transition metal precursor, and then the separated complex transition metal precursor is washed and dried to obtain the complex transition metal precursor. At this time, processes such as grinding and / or classification may also be performed, as needed.

[0138]

[0139] According to one embodiment of the present invention, the composite transition metal hydroxide in step (A) may have a composition represented by the following chemical formula 2.

[0140] [Chemical Formula 2]

[0141] Ni p Mn q Co r M 3 s (OH)2

[0142] In the above chemical formula 2,

[0143] M 3 is at least one selected from the group consisting of B, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo and W,

[0144] 0.600≤p<1.000, 0.000 <q<0.400, 0.000<r<0.400, 0.000≤s≤0.010이다.

[0145] Above M 3 is a doping element, specifically the above M 3 M may be at least one selected from the group consisting of B, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo and W. 3 Although not necessarily included, 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.

[0146] The above p is the molar ratio of nickel (Ni) among the total metals in the complex transition metal hydroxide, and may be 0.600 or more, 0.650 or more, 0.700 or more, 0.750 or more, 0.800 or more, or 0.850 or more, and may be 0.900 or less, 0.950 or less, or less than 1.000.

[0147] The molar ratio of manganese (Mn) among all metals in the above q complex transition metal hydroxide may be greater than 0, 0.010 or more, 0.020 or more, 0.030 or more, 0.040 or more, or 0.050 or more, and may be 0.060 or less, 0.070 or less, 0.080 or less, 0.090 or less, 0.100 or less, 0.200 or less, 0.300 or less, or less than 0.400.

[0148] The above r is a molar ratio of cobalt (Co) among all metals in the complex transition metal hydroxide, and may be greater than 0.000, 0.010 or more, 0.020 or more, 0.030 or more, 0.040 or more, or 0.050 or more, and may be 0.060 or less, 0.070 or less, 0.080 or less, 0.090 or less, 0.100 or less, 0.200 or less, 0.300 or less, or less than 0.400.

[0149] The above s is M among all metals in the complex transition metal hydroxide. 3 The molar ratio may be 0.000 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, 0.007 or less, 0.008 or less, 0.009 or less, or 0.010 or less.

[0150]

[0151] 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, LiOH, which has a low melting point and excellent reactivity, may be used as the lithium (Li)-containing raw material.

[0152]

[0153] The above aluminum (Al)-containing raw material may be at least one selected from the group consisting of Al2O3, AlF3, and Al(OH)3, and a mixture of one or more of these may be used. Specifically, Al(OH)3, which has excellent reactivity, may be used as the aluminum-containing raw material.

[0154]

[0155] Above M1 Contains raw materials M 1 It may be at least one selected from the group consisting of oxides, hydroxides, and sulfuric acid hydrates, and a mixture of one or more of these may be used. Specifically, M 1 As raw materials containing Zr(OH)2 and Ba(OH), which have relatively low reaction temperatures, 2· H2O or Sr(OH) 2· 8H2O can be used.

[0156]

[0157] According to one embodiment of the present invention, in the step (A), the aluminum (Al)-containing raw material may be mixed so that the aluminum (Al) content is 1,000 ppm or more and 5,000 ppm or less based on the total weight of the composite transition metal hydroxide. Specifically, in the step (A), the aluminum (Al)-containing raw material may be mixed so that the aluminum (Al) content is 1,000 ppm or more, 1,500 ppm or more, 2,000 ppm or more, or 2,500 ppm or more, and 3,000 ppm or less, 3,500 ppm or less, 4,000 ppm or less, 4,500 ppm or less, or 5,000 ppm or less based on the total weight of the composite transition metal hydroxide. When the aluminum (Al)-containing raw material is within the above range, it can act as a pillar in the crystal structure of the positive electrode active material, thereby improving structural stability and improving life characteristics.

[0158]

[0159] According to one embodiment of the present invention, in step (A), the M 1 The raw material contained is M based on the total weight of the above complex transition metal hydroxide. 1 It may be mixed so that the content is 500 ppm or more and 4,000 ppm or less. Specifically, in the step (A) above, M 1The raw material contained is M based on the total weight of the above complex transition metal hydroxide. 1 It may be mixed so that the content is 500 ppm or more, or 1,000 ppm or more, and 3,000 ppm or less, 3,500 ppm or less, or 4,000 ppm or less. The above M 1 When the contained raw material is within the above range, structural stability can be improved, life characteristics can be improved, and crystal growth can be assisted to increase the degree of single crystallinity.

[0160]

[0161] According to one embodiment of the present invention, the lithium (Li)-containing raw material, the composite transition metal hydroxide, and the aluminum (Al)-containing raw material may be mixed such that the molar ratio (M:Li:Al) of lithium (Li) and aluminum (Al) contained in the transition metal (M) contained in the composite transition metal hydroxide, the lithium (Li)-containing raw material, and the aluminum (Al)-containing raw material is 1:1:0.001 to 1:1.1:0.010. In this case, not only can excessive lithium be prevented from entering the positive electrode active material structure, but also the content of unreacted residual lithium can be low.

[0162]

[0163] (B) Step

[0164] After the above step (A), the above step (B) includes calcining the mixture at a temperature of 800°C or higher and 1,000°C or lower to manufacture a plastic product.

[0165]

[0166] The above sintering may be performed at a temperature of 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, or 870°C or higher, and 900°C or lower, 910°C or lower, 920°C or lower, 930°C or lower, 940°C or lower, 950°C or lower, 960°C or lower, 970°C or lower, 980°C or lower, 990°C or lower, or 1,000°C or lower. By performing the sintering in this manner, a lithium composite transition metal oxide in the form of a single particle can be formed. When the lithium composite transition metal oxide is in the form of a single particle, the structural stability is improved, particle breakage is suppressed during rolling, and gas generation due to a side reaction with an electrolyte is reduced, thereby improving the life characteristics of a secondary battery. When calcination is performed at a temperature below 800°C, there is a problem that the single crystallinity is low because the particles do not grow sufficiently, and when calcination is performed at a temperature exceeding 1,000°C, there is a problem that rock salt phases such as NiO are generated due to undercalcination.

[0167]

[0168] According to one embodiment of the present invention, the calcination may be performed under an oxygen atmosphere. In this case, nickel oxide, an impurity, can be reduced, and sufficient oxygen necessary for the reaction can be provided, allowing for more efficient calcination.

[0169]

[0170] According to one embodiment of the present invention, the calcination may be performed for a period of 4 hours or more and 9 hours or less. Specifically, the calcination may be performed for a period of 4 hours or more, or 5 hours or more, and 8 hours or less, or 9 hours or less. When the calcination time satisfies the above range, highly crystalline particles with an appropriate size can be obtained, and production efficiency can be improved.

[0171]

[0172] (C) Step

[0173] After the above step (B), the above step (C) includes mixing a lithium (Li)-containing raw material and calcining it at a temperature of 720°C or higher and 900°C or lower to produce a lithium composite transition metal oxide.

[0174]

[0175] According to one embodiment of the present invention, in the step (C), the lithium (Li)-containing raw material is a lithium composite transition metal oxide containing all metals (Ni+Co+Mn+Al+M) excluding lithium. 1 ) and the total lithium (Li) may be mixed so that the molar ratio is 1:1.00 or more, 1:1.01 or more, 1:1.02 or more, 1:1.03 or more, or 1:1.04 or more, and 1:1.05 or less, 1:1.06 or less, 1:1.07 or less, 1:1.08 or less, 1:1.09 or less, or 1:1.10 or less. The 'total lithium (Li)' above is related to the amount of lithium included in the lithium (Li) raw material mixed during calcination and firing. Specifically, it is the number of moles of lithium present in the lithium composite transition metal oxide when the entire metal excluding lithium present in the lithium composite transition metal oxide is converted to 1 mole. When the molar ratio is within the above range, there is an effect of helping to recover the crystal structure of the calcined product.

[0176]

[0177] In the present invention, the sintering is performed at a temperature of 720°C or higher and 900°C or lower. Specifically, it may be performed at a temperature of 720°C or higher, 730°C or higher, 740°C or higher, 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, or 820°C or higher, and 830°C or lower, 840°C or lower, 850°C or lower, 860°C or lower, 870°C or lower, 880°C or lower, 890°C or lower, or 900°C or lower. When sintering is performed within the above range, the crystal structure of the sintered product is restored by the additionally added lithium ions, thereby reducing the degree of deformation of the internal structure of the particles, and is effective in improving the structural stability and capacity characteristics of the positive electrode active material. When calcination is performed at a temperature lower than 720℃, it is difficult to recover the crystal structure of the calcined product because it does not sufficiently react with the additionally added lithium ions, the degree of deformation of the internal structure of the particles is not reduced, and there is a problem that the content of unreacted residual lithium is high. When calcination is performed at a temperature higher than 900℃, there is a problem that a rock salt phase such as NiO is generated due to overcalcination, and the content of residual lithium is high.

[0178]

[0179] According to one embodiment of the present invention, the firing may be performed under an oxygen atmosphere. In this case, nickel oxide, an impurity, can be reduced, and sufficient oxygen required for the reaction can be provided, allowing for more efficient firing.

[0180]

[0181] According to one embodiment of the present invention, the firing is performed for 5 hours or more and 20 hours or less. Specifically, the firing may be performed for 5 hours or more, or 6 hours or more, and 12 hours or less, 13 hours or less, 14 hours or less, 15 hours or less, 16 hours or less, 17 hours or less, 18 hours or less, 19 hours or less, or 20 hours or less. When the firing satisfies the time range, highly crystalline particles having an appropriate size can be obtained, and production efficiency can be improved.

[0182]

[0183] In the present invention, the sintering is performed for a shorter period of time than the above-described calcination. In this case, the sintering has the effect of synthesizing the crystal structure at a relatively short, high temperature, and then slowly restoring the crystal structure of the sintered product over a relatively long period of time. If the sintering is performed for a shorter period of time than the above-described calcination, the crystal structure of the positive electrode active material is difficult to recover, resulting in poor capacity characteristics and cycle life.

[0184]

[0185] According to one embodiment of the present invention, the plasticization may be performed at a higher temperature than the calcination. In this case, this is because the plasticization step, i.e., crystal structure synthesis and grain growth, requires higher energy, and by performing the plasticization at a higher temperature than the calcination, the degree of single crystallinity can be controlled.

[0186]

[0187] anode

[0188] Next, the anode according to the present invention will be described.

[0189] 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.

[0190]

[0191] 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.

[0192]

[0193] The above-mentioned positive electrode active material layer may include a conductive material and a binder together with the positive electrode active material. 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 characteristics may be exhibited within this range.

[0194]

[0195] 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.

[0196]

[0197] 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.

[0198]

[0199] 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.

[0200]

[0201] 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.

[0202]

[0203] lithium secondary battery

[0204] Next, a lithium secondary battery according to the present invention will be described.

[0205]

[0206] 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.

[0207]

[0208] 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.

[0209]

[0210] 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.

[0211]

[0212] 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.

[0213] 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.

[0214]

[0215] The above negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0216]

[0217] 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.

[0218] 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.

[0219]

[0220] 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.

[0221]

[0222] 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.

[0223]

[0224] 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.

[0225]

[0226] 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.

[0227]

[0228] 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.

[0229] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0230] 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.

[0231]

[0232] 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.

[0233]

[0234] 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.

[0235]

[0236] 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).

[0237] 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.

[0238] 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.

[0239] 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.

[0240] 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.

[0241]

[0242] 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.

[0243]

[0244] Manufacturing example

[0245] NiSO 4· 6H2O, CoSO 4· 7H2O and MnSO 4· A 4M complex transition metal aqueous solution was prepared by mixing H2O in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 89:5:6. After mixing 10 L of the complex transition metal aqueous solution, 5 L / hr of 4 M NaOH aqueous solution, and 2 L / hr of 0.4 M NH4OH aqueous solution, stirring was performed at 50°C to adjust the pH of the solution to 11 and co-precipitation was performed for 90 to 100 hours to obtain Ni. 0.89 Co 0.05 Mn 0.06 Complex transition metal hydroxides having a composition represented by (OH)2 (average particle diameter (D 50 ): 4.0㎛) was manufactured.

[0246]

[0247] Examples and Comparative Examples

[0248] Example 1

[0249] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co 0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.03:0.005, and Zr(OH)2 was added to Ni 0.89 Co 0.05 Mn 0.06 A mixture was prepared by mixing Zr to a content of 1,400 ppm with respect to the total weight of (OH)2. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0250] The above mixture was calcined at a temperature of 870°C in an oxygen atmosphere for 6 hours to produce a calcined product.

[0251] LiOH was mixed in the above-mentioned plastic product so that the molar ratio of (Ni+Co+Mn+Al+Zr) and total Li ((Ni+Co+Mn+Al+Zr):Li) was 1:1.04, and calcined at a temperature of 820°C in an oxygen atmosphere for 10 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0252]

[0253] Example 2

[0254] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co 0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.01:0.005, and Zr(OH)2 was added to Ni 0.89 Co 0.05 Mn 0.06 A mixture was prepared by mixing Zr to a content of 1,400 ppm with respect to the total weight of (OH)2. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0255]

[0256] The above mixture was calcined at a temperature of 900°C in an oxygen atmosphere for 8 hours to produce a calcined product.

[0257] LiOH was mixed in the above-mentioned plastic product so that the molar ratio of (Ni+Co+Mn+Al+Zr) and total Li ((Ni+Co+Mn+Al+Zr):Li) was 1:1.04, and calcined at a temperature of 820°C in an oxygen atmosphere for 12 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0258]

[0259] Example 3

[0260] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89Co 0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.03:0.005, and Zr(OH)2 was added to Ni 0.89 Co 0.05 Mn 0.06 A mixture was prepared by mixing Zr to a content of 2,800 ppm with respect to the total weight of (OH)2. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0261]

[0262] The above mixture was calcined at a temperature of 870°C in an oxygen atmosphere for 6 hours to produce a calcined product.

[0263] LiOH was mixed into the above-mentioned plastic product so that the molar ratio of (Ni+Co+Mn+Al+Zr) and total Li was ((Ni+Co+Mn+Al+Zr):Li), and calcined at a temperature of 820°C in an oxygen atmosphere for 10 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0264]

[0265] Example 4

[0266] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co 0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.03:0.005, and Zr(OH)2 was added to Ni 0.89 Co 0.05 Mn 0.06 A mixture was prepared by mixing Zr to a content of 1,400 ppm with respect to the total weight of (OH)2. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06(OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0267]

[0268] The above mixture was calcined at a temperature of 900°C in an oxygen atmosphere for 5 hours to produce a calcined product.

[0269] LiOH was mixed in the above-mentioned plastic product so that the molar ratio of (Ni+Co+Mn+Al+Zr) and total Li ((Ni+Co+Mn+Al+Zr):Li) was 1:1.04, and calcined at a temperature of 830°C in an oxygen atmosphere for 6 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0270]

[0271] Example 5

[0272] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co 0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.03:0.005, and Ba(OH) 2· H2O to Ni 0.89 Co 0.05 Mn 0.06 A mixture was prepared by mixing Ba to a content of 1,400 ppm with respect to the total weight of (OH)2. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0273] The above mixture was calcined at a temperature of 900°C in an oxygen atmosphere for 6 hours to produce a calcined product.

[0274] LiOH was mixed in the above-mentioned plastic product so that the molar ratio of (Ni+Co+Mn+Al+Ba) and total Li ((Ni+Co+Mn+Al+Ba):Li) was 1:1.04, and calcined at a temperature of 820°C in an oxygen atmosphere for 10 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0275]

[0276] Example 6

[0277] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co 0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.03:0.005, and Sr(OH) 2· 8H2O to Ni 0.89 Co 0.05 Mn 0.06 A mixture was prepared by mixing Sr to a content of 1,400 ppm with respect to the total weight of (OH)2. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0278] The above mixture was calcined at a temperature of 900°C in an oxygen atmosphere for 6 hours to produce a calcined product.

[0279] LiOH was mixed in the above-mentioned plastic product so that the molar ratio of (Ni+Co+Mn+Al+Sr) and total Li ((Ni+Co+Mn+Al+ Ba):Sr) was 1:1.04, and calcined at a temperature of 820°C in an oxygen atmosphere for 10 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0280]

[0281] Comparative Example 1

[0282] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.04:0.005 to prepare a mixture. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 970 ppm with respect to the total weight.

[0283] The above mixture was calcined at a temperature of 750°C in an oxygen atmosphere for 6 hours to produce a calcined product.

[0284] The above-mentioned plastic product was fired at a temperature of 700°C in an oxygen atmosphere for 10 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of secondary particles.

[0285]

[0286] Comparative Example 2

[0287] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co 0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.03:0.005, and Zr(OH)2 was added to Ni 0.89 Co 0.05 Mn 0.06 A mixture was prepared by mixing Zr to a content of 1,400 ppm with respect to the total weight of (OH)2. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0288] The above mixture was calcined at a temperature of 750°C in an oxygen atmosphere for 6 hours to produce a calcined product.

[0289] LiOH was mixed in the above-mentioned plastic product so that the molar ratio of (Ni+Co+Mn+Al+Zr) and total Li ((Ni+Co+Mn+Al+Zr):Li) was 1:1.04, and calcined at a temperature of 700°C in an oxygen atmosphere for 10 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0290]

[0291] Comparative Example 3

[0292] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co 0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.04:0.005, and Zr(OH)2 was added to Ni 0.89 Co 0.05 Mn 0.06 A mixture was prepared by mixing Zr to a content of 1,400 ppm with respect to the total weight of (OH)2. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0293]

[0294] The above mixture was calcined at a temperature of 900°C in an oxygen atmosphere for 10 hours to produce a calcined product.

[0295] The above-mentioned plastic product was fired at a temperature of 830°C in an oxygen atmosphere for 6 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0296]

[0297] Comparative Example 4

[0298] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co 0.05 Mn 0.06(OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.04:0.005 to prepare a mixture. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0299] The above mixture was calcined at a temperature of 800°C in an oxygen atmosphere for 15 hours to produce a calcined product.

[0300] The above-mentioned plastic product was fired at a temperature of 700°C in an oxygen atmosphere for 20 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0301]

[0302] Comparative Example 5

[0303] Composite transition metal hydroxide Ni prepared in the manufacturing example 0.89 Co 0.05 Mn 0.06 (OH)2, LiOH and Al(OH)3 were mixed so that the molar ratio of (Ni+Co+Mn):Li:Al was 1:1.04:0.005 to prepare a mixture. At this time, Al(OH)3 is the Ni 0.89 Co 0.05 Mn 0.06 (OH)2 is mixed so that the content of Al is 2,900 ppm with respect to the total weight.

[0304] The above mixture was calcined at a temperature of 880°C in an oxygen atmosphere for 5 hours to produce a calcined product.

[0305] The above-mentioned plastic product was fired at a temperature of 800°C in an oxygen atmosphere for 10 hours to produce a lithium composite transition metal oxide (positive electrode active material) in the form of a single particle.

[0306]

[0307] Experimental example

[0308] Experimental Example 1: ICP Analysis

[0309] Each of the positive electrode active materials manufactured in the above examples and comparative examples was taken in an amount of 0.1 g, 1 ml of hydrochloric acid was added, and 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. Next, the solution was diluted with deionized water to a total volume of 10 ml to prepare an analysis sample. Using an ICP device (Perkin Elmer, OPTIMA 7300DV), the weight ratio of the constituent elements present in the analysis sample was measured, and the composition of the lithium composite transition metal oxide and the content of zirconium (ppm) are shown in Table 1 below.

[0310]

[0311] Composition M 1 Content (ppm) Example 1Li 1.04 Ni 0.880 Mn 0.060 Co 0.050 Al 0.005 Zr 0.005 O21,370 Example 2Li 1.04 Ni 0.880 Mn 0.060 Co 0.050 Al 0.005 Zr 0.005 O21,390 Example 3Li 1.04 Ni 0.875 Mn 0.060 Co 0.050 Al 0.005 Zr 0.01 O22,720 Example 4Li 1.04 Ni 0.880 Mn 0.060 Co 0.050 Al 0.005 Zr 0.005 O21,380 Example 5Li 1.04 Ni 0.880 Mn 0.060 Co 0.050 Al 0.005 Ba 0.005 O21,410 Example 6Li 1.04 Ni 0.880 Mn 0.060 Co0.050 Al 0.005 Sr 0.005 O21,380 Comparative Example 1Li 1.04 Ni 0.888 Mn 0.060 Co 0.050 Al 0.002 O2-Comparative Example 2Li 1.04 Ni 0.880 Mn 0.060 Co 0.050 Al 0.005 Zr 0.005 O21,390 Comparative Example 3Li 1.04 Ni 0.880 Mn 0.060 Co 0.050 Al 0.005 Zr 0.005 O21,370 Comparative Example 4Li 1.04 Ni 0.885 Mn 0.060 Co 0.050 Al 0.005 O2-Comparative Example 5Li 1.04 Ni 0.885 Mn 0.060 Co 0.050 Al 0.005 O2-

[0312] Through Table 1, the lithium composite transition metal oxides manufactured in Examples 1 to 6 have a composition represented by the chemical formula 1 described in the present invention, and the M 1 It was confirmed that the content was 500 ppm to 4,000 ppm based on the total weight of the lithium composite transition metal oxide. Meanwhile, it was confirmed that the lithium composite transition metal oxides manufactured in Comparative Examples 1, 4, and 5 did not have the composition represented by Chemical Formula 1 described in the present invention.

[0313]

[0314] Experimental Example 2: SEM Analysis

[0315] For each of the positive electrode active materials manufactured in the above examples and comparative examples, SEM images were obtained using a scanning electron microscope (SEM) (JEOL, JSM7610F), and these are shown in Figures 1 to 11.

[0316]

[0317] Figure 1 is a SEM image of the positive electrode active material manufactured in Example 1.

[0318] Figure 2 is a SEM image of the positive electrode active material manufactured in Example 2.

[0319] Figure 3 is a SEM image of the positive electrode active material manufactured in Example 3.

[0320] Figure 4 is an SEM image of the positive electrode active material manufactured in Example 4.

[0321] Figure 5 is an SEM image of the positive electrode active material manufactured in Example 5.

[0322] Figure 6 is an SEM image of the positive electrode active material manufactured in Example 6.

[0323] Figure 7 is an SEM image of the positive electrode active material manufactured in Comparative Example 1.

[0324] Figure 8 is an SEM image of the positive electrode active material manufactured in Comparative Example 2.

[0325] Figure 9 is an SEM image of the positive electrode active material manufactured in Comparative Example 3.

[0326] Figure 10 is an SEM image of the positive electrode active material manufactured in Comparative Example 4.

[0327] Figure 11 is an SEM image of the positive electrode active material manufactured in Comparative Example 5.

[0328]

[0329] Through Figures 1 to 11, it was confirmed that the positive electrode active materials manufactured in Examples 1 to 6 according to the present invention and the positive electrode active materials manufactured in Comparative Examples 2 to 5 were in the form of single particles. Meanwhile, it was confirmed that the positive electrode active material manufactured in Comparative Example 1 was in the form of secondary particles.

[0330] In addition, it was confirmed through Figures 1 to 6 that the positive electrode active materials manufactured in Examples 1 to 6 had a relatively uniform particle size without fine particles or agglomerates of multiple particles.

[0331]

[0332] Experimental Example 3: XRD Analysis

[0333] For each positive electrode active material manufactured in the above examples and comparative examples, the average crystallite size (α) after XRD measurement is shown in Table 2 below.

[0334] At this time, the XRD measurement was performed using Bruker's AXS D4 Endeavor, and 2 to 3 g of positive electrode active material particles were collected from each positive electrode active material powder, and measured at a scan speed of 0.2 ° / sec from 2θ 15 ° to 80 ° under Cu-Kα radiation (wavelength 1.54 Å, acceleration voltage 40 kV, current 40 mA).

[0335]

[0336] Experimental Example 4: Measurement of average particle size

[0337] The average particle diameter (D) of each positive electrode active material particle manufactured in the above examples and comparative examples 50 ) was measured using PSA (Microtrac, S3500), and the single crystallinity was calculated according to Equation 1 described in this specification to obtain the average particle diameter (D 50 ) and single crystallinity (χ) are shown in Table 2 below.

[0338]

[0339] Average particle size (α) [nm] Average particle diameter (D 50 )[㎛] Single crystallinity (χ) Example 1 233.9 3.8 2 0.06 12 Example 2 27 0.04 11 0.06 57 Example 3 234.6 3.9 5 0.05 94 Example 4 213.03 77 0.05 65 Example 5 240.23 8 3 0.06 27 Example 6 245.43 9 3 0.06 24 Comparative Example 1 92.5 3.5 3 0.02 62 Comparative Example 2 152.63 6 0.04 17 Comparative Example 3 333.24 18 0.07 97 Comparative Example 4 322.5 3.4 6 0.09 32 Comparative Example 5 262.7 4.2 3 0.06 21

[0340] Through Table 2, the positive electrode active materials of Examples 1 to 6 have an average crystallite size (α) of 170.0 nm or more and 300.0 nm or less, and an average particle diameter (D 50 ) was confirmed to be 3.00㎛ or more and 5.00㎛ or less. In addition, it was confirmed that the single crystallinity (χ) was 0.0500 or more and 0.0750 or less. In contrast, it was confirmed that the positive electrode active materials of Comparative Examples 1 and 2 had an average crystallite size (α) of less than 170.0 nm and a single crystallinity (χ) of less than 0.0500, and it was confirmed that the positive electrode active materials of Comparative Examples 3 and 4 had an average crystallite size (α) of more than 300.0 nm and a single crystallinity (χ) of more than 0.0750.

[0341] Through examples and comparative examples, it can be seen that the single crystallinity (χ) according to formula 1 described in the present specification is a technical characteristic that appears by comprehensively controlling the sintering step, sintering and plasticizing temperature, sintering time, and input amount of raw materials when manufacturing a positive electrode active material.

[0342]

[0343] Experimental Example 5: Battery Characteristics Evaluation

[0344] Coin-type half-cell manufacturing

[0345] 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 carbon black 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 100°C, and then rolled to prepare a positive electrode.

[0346] 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 1.0 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.

[0347]

[0348] Battery Characteristics Evaluation

[0349] Using the coin-type half-cell manufactured as described above, the activation process (formation) was performed by charging to 4.25 V using the CC (0.1 C)-CV (Cut off current: 0.05 C) method at 45°C and discharging to 2.5 V using the CC (0.1 C) method.

[0350]

[0351] After performing the activation process, the battery was charged to 4.25 V using the CC (0.1 C)-CV (Cut off current: 0.05 C) method at 25°C, discharged to 2.5 V using the CC (0.1 C) method, and the discharge capacity at this time was measured. The measured discharge capacity (mAh / g) is shown in Table 3 below.

[0352]

[0353] Discharge capacity (mAh / g) Example 1208.2 Example 2207.4 Example 3207.5 Example 4205.9 Example 5206.7 Example 6206.3 Comparative Example 1201.3 Comparative Example 2202.9 Comparative Example 3203.5 Comparative Example 4203.0 Comparative Example 5203.4

[0354] Through Table 3, it was confirmed that the batteries including the positive electrode active materials of Examples 1 to 6, that is, the positive electrode active materials having the single crystallinity (χ) of 0.0500 or more and 0.0750 or less, had a greater discharge capacity than the batteries including the positive electrode active materials of Comparative Examples 1 to 4, that is, the positive electrode active materials having the single crystallinity (χ) of less than 0.0500 or greater than 0.0750, and the positive electrode active material of Comparative Example 5, that is, the positive electrode active material not having the composition represented by Chemical Formula 1 described herein. In conclusion, it can be seen that the positive electrode active material according to the present invention can secure an optimal migration path during desorption and insertion of lithium ions by controlling the crystal grain boundaries that serve as the migration paths of lithium ions inside the positive electrode active material particles, thereby improving the capacity characteristics.

[0355]

[0356] Life Characteristics Assessment

[0357] Using the coin-type half-cell manufactured as described above, a cycle of charging (0.5C) to 4.25 V at 45°C using the CC-CV method, and then discharging (1.0C) to 3.0 V using the CC method was considered as one cycle, and a total of 50 cycles of charging and discharging were repeated, and the discharge capacities from the first to the 50th cycles were measured, and then the percentage of the discharge capacity of the nth cycle (n is from 1 to 50) to the measured discharge capacity of the first cycle (capacity retention rate (%)) was calculated, and the capacity retention rate (cycle retention (%)) according to the cycle of each battery including the positive electrode active material of the examples and comparative examples is shown in FIG. 12.

[0358] Through Fig. 12, it was confirmed that the batteries including the positive electrode active materials of Examples 1 to 6 had superior life characteristics compared to the batteries including the positive electrode active materials of Comparative Examples 1 to 5.

Claims

1. Contains a lithium composite transition metal oxide having a composition represented by the following chemical formula 1, The above lithium composite transition metal oxide is in the form of a single particle, The above lithium composite transition metal oxide is a cathode active material having a single crystallinity (χ) of 0.0500 or more and 0.0750 or less according to the following formula 1: [Chemical Formula 1] Li 1+x Ni a Mr b Co c Al d M 1 e M 2 f O2 In the above chemical formula 1, M 1 is at least one selected from the group consisting of Zr, K, Sr and Ba, M 2 is at least one selected from the group consisting of B, Ce, Cr, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo and W, 0.0≤x≤0.1, 0.600≤a<1.000, 0.000 <b<0.400, 0.000<c<0.400, 0.000<d≤0.100, 0.000<e≤0.100, 0.000≤f≤0.010이고, [Formula 1] am.

2. In claim 1, A cathode active material having a single crystallinity (χ) of 0.0550 or more and 0.0700 or less.

3. In claim 1, Above M 1 A cathode active material comprising at least one selected from the group consisting of Zr, Sr, and Ba.

4. In claim 1, M in the above lithium complex transition metal oxide 1 A cathode active material having a content of 500 ppm or more and 4,000 ppm or less based on the total weight of the lithium composite transition metal oxide.

5. In claim 1, The above lithium composite transition metal oxide is a positive electrode active material having an average crystallite size (α) of 170.0 nm or more and 300.0 nm or less.

6. In claim 1, The above lithium composite transition metal oxide has an average particle diameter (D 50 ) is a positive electrode active material having a particle size of 3.00㎛ or more and 5.00㎛ or less.

7. A positive electrode comprising the positive electrode active material of any one of claims 1 to 6.

8. A lithium secondary battery comprising the positive electrode of claim 7.