Positive electrode active material, its manufacturing method, positive electrode and lithium secondary battery including the same

Abstract

The positive electrode active material according to the present invention includes a single particle consisting of one single nodule, a quasi-single particle which is a composite of 30 or less nodules, or a combination thereof, and includes a lithium nickel-based oxide in which the molar ratio of Ni among all transition metals is 60 mol % or more, and has a negative skewness factor (NSF) represented by the following formula 1 of 0.20 to 0.35. [Formula 1] NSF=(D 50 -D 10 ) / I max (In the above formula 1, D 50 is the particle size at the point where the cumulative volume is 50% in the volume cumulative particle size distribution graph of the positive electrode active material, and D 10 is the particle size at the point where the cumulative distribution is 10% in the volume cumulative particle size distribution graph of the positive electrode active material, and I max is the maximum volume fraction in the volume cumulative particle size distribution graph of the positive electrode active material.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application Nos. 10-2022-0166990, 10-2022-0166991, and 10-2023-0172466, filed December 2, 2022, and the entire contents of the documents of said Korean patent applications are incorporated herein by reference.

[0002] 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. [Background technology]

[0003] A lithium secondary battery generally comprises a positive electrode, a negative electrode, a separator, and an electrolyte, and the positive electrode and the negative electrode contain active materials capable of intercalating and deintercalating lithium ions.

[0004] Lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2 or LiMnO4, etc.), and lithium iron phosphate (LiFePO4) have been used as positive electrode active materials for lithium secondary batteries. Among these, lithium cobalt oxide has the advantages of high operating voltage and excellent capacity characteristics, but the high cost and unstable supply of cobalt, the raw material, make its commercial application in large-capacity batteries difficult. Lithium nickel oxide has poor structural stability and is difficult to achieve sufficient life characteristics. On the other hand, lithium manganese oxide has excellent stability but poor capacity characteristics. Therefore, to address the issues of lithium transition metal oxides containing only Ni, Co, or Mn, lithium composite transition metal oxides containing two or more transition metals have been developed. Among them, lithium nickel cobalt manganese oxide containing Ni, Co, and Mn is widely used in the field of electric vehicle batteries.

[0005] Conventional lithium nickel cobalt manganese oxides generally have a spherical secondary particle form, consisting of an agglomeration of tens to hundreds of primary particles. However, when using lithium nickel cobalt manganese oxides in this secondary particle form, consisting of an agglomeration of many primary particles, particle cracking occurs easily during the rolling process in the manufacture of the positive electrode, and cracks occur inside the particles during charge and discharge. When particle cracking or cracking occurs in the positive electrode active material, the contact area with the electrolyte increases, which increases the generation of gas due to side reactions with the electrolyte and the degradation of the active material, resulting in reduced life characteristics.

[0006] To address these issues, a technique has been proposed for producing a single-particle cathode active material rather than a secondary particle by increasing the calcination temperature during the preparation of lithium nickel cobalt manganese oxide. Single-particle cathode active materials have a smaller contact area with the electrolyte than conventional secondary-particle cathode active materials, resulting in fewer side reactions with the electrolyte and superior particle strength, resulting in less particle cracking during electrode fabrication. Therefore, the use of single-particle cathode active materials offers the advantages of less gas generation and excellent lifespan characteristics. However, conventional single-particle cathode active materials have a high resistance, which limits the ability to achieve sufficient output performance.

[0007] Meanwhile, the tap density and pellet density can be increased simply by increasing the average particle size of a single-particle positive electrode active material. However, if the average particle size increases beyond a certain level, the diffusion distance of lithium ions within the particles increases, resulting in an increase in initial resistance.

[0008] Therefore, a technique is needed that can reduce the average particle size of the single particle positive electrode active material as much as possible and increase the pellet density. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the above problems, and an object of the present invention is to provide a positive electrode active material that has a specific particle size distribution and therefore has low initial resistance characteristics and high energy density, a method for producing the same, and a positive electrode and a lithium secondary battery that include the same. [Means for solving the problem]

[0010] In one aspect, the present invention provides a cathode active material including a single particle consisting of one single nodule, a quasi-single particle that is a composite of 30 or less nodules, or a combination thereof, the cathode active material including a lithium nickel-based oxide in which the molar ratio of Ni to all transition metals is 60 mol % or more, and having a negative skewness factor (NSF) represented by the following formula 1 of 0.20 to 0.35: [Formula 1] NSF=(D 50 -D 10 ) / I max In the formula 1, D 50 is the particle size at the point where the cumulative volume is 50% in the volume cumulative particle size distribution graph of the positive electrode active material, and D 10 is the particle size at the point where the cumulative distribution is 10% in the volume cumulative particle size distribution graph of the positive electrode active material, and I max is the maximum volume fraction in the volume cumulative particle size distribution graph of the positive electrode active material.

[0011] D of the positive electrode active material 50 The thickness can be 5.0 μm to 7.0 μm.

[0012] The lithium nickel-based oxide may be represented by the following Chemical Formula 1: [Chemical formula 1] Li a Ni b Co c M 1 d M 2 e O2 In the above Chemical Formula 1, M 1 is Mn, Al or a combination thereof, and M2 is one or more elements selected from the group consisting of Ba, Ca, Zr, Ti, Mg, Ta, Nb, and Mo, and 1.0≦a≦1.5, 0.6≦b<1.0, 0 <c<0.1、0<d<0.2、0≦e≦0.1、0<c+d+e≦0.4である。

[0013] The positive electrode active material nodules may have an average particle size of 1.0 μm to 7.0 μm.

[0014] The tap density of the positive electrode active material may be 2.40 g / cc to 2.60 g / cc.

[0015] The positive electrode active material may have a pellet density (9 tons) of 3.60 g / cc to 3.80 g / cc.

[0016] The initial resistance of a mono-cell manufactured using the positive electrode active material at SOC50 may be 1.45Ω to 1.50Ω.

[0017] In another aspect, the present invention provides a method for producing a cathode active material, the method including the steps of: mixing a cathode active material precursor and a lithium source material; and primarily firing the mixture; and pulverizing the primarily fired mixture; and secondarily firing the mixture.

[0018] The positive electrode active material precursor is D 50 The thickness can be 4.0 μm to 10.0 μm.

[0019] The grinding can be carried out by jet-mill grinding.

[0020] The jet-mill pulverization may be carried out under conditions of 2.0 bar to 4.0 bar and 1000 rpm to 2500 rpm.

[0021] In another aspect, the present invention provides a positive electrode including the above-described positive electrode active material and a lithium secondary battery including the positive electrode. [Effects of the Invention]

[0022] In the cathode active material according to the present invention, the NSF satisfies a specific range, so that the spaces between the relatively large particles are filled by the small particles, thereby increasing the tap density and pellet density, and a lithium secondary battery including the cathode active material can achieve a high energy density.

[0023] In addition, the positive electrode active material according to the present invention has an NSF that satisfies a specific range, thereby reducing the diffusion distance of lithium ions within the particles, and a lithium secondary battery including the positive electrode active material can achieve low initial resistance. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a graph showing the volume cumulative particle size distribution of the positive electrode active materials produced in Examples 1 to 4 of the present invention and Comparative Examples 1 to 4. [Figure 2] 1 is a graph showing the tap density as a function of D50 of the positive electrode active materials produced in Examples 1 to 4 of the present invention and Comparative Examples 1 to 4. [Figure 3] 1 is a graph showing pellet density as a function of D50 of positive electrode active materials produced in Examples 1 to 4 of the present invention and Comparative Examples 1 to 4. [Figure 4] 1 is a graph showing pellet density as a function of NSF value for positive electrode active materials produced in Examples 1 to 4 of the present invention and Comparative Examples 1 to 4. [Figure 5] 1 is a graph showing the initial resistance as a function of D50 of lithium secondary batteries including the positive electrode active materials prepared according to Examples 1 to 4 and Comparative Examples 1 to 4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The terms and words used in this specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, but are to be construed as meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0026] In the present invention, a "single particle" refers to a particle consisting of one single nodule. In the present invention, a "quasi-single particle" refers to a particle that is a complex formed by 30 or fewer nodules.

[0027] In the present invention, the term "nodule" refers to a particle unit body constituting a single particle or a quasi-single particle, and the nodule may be a single crystal lacking a crystalline grain boundary, or a polycrystal lacking a grain boundary when observed at a magnification of 5,000 to 20,000 times using a scanning electron microscope (SEM). The average particle size of the nodules may be measured as the arithmetic mean value of the particle sizes of the respective nodules measured using a scanning electron microscope (SEM).

[0028] In the present invention, the term "secondary particles" refers to particles formed by agglomeration of several tens to several hundreds of primary particles. More specifically, secondary particles are agglomerations of 40 or more primary particles.

[0029] The term "particle" as used in the present invention can include any one or all of single particles, quasi-single particles, primary particles, nodules, and secondary particles.

[0030] In the present invention, "D 50 " means the particle size at 50% of the volume cumulative particle size distribution of the positive electrode active material. 50 can be measured using a laser diffraction method. For example, the positive electrode active material powder is dispersed in a dispersion medium, introduced into a commercially available laser diffraction particle size analyzer (e.g., Microtrac MT 3000), and irradiated with ultrasonic waves of about 28 kHz at an output of 60 W. A volume cumulative particle size distribution graph is obtained, and the particle diameter corresponding to 50% of the volume cumulative amount is determined.

[0031] The present invention will now be described in further detail.

[0032] positive electrode active material The positive electrode active material according to the present invention includes a single particle consisting of one single nodule, a quasi-single particle which is a composite of 30 or less nodules, or a combination thereof.

[0033] Lithium nickel-based oxides in the form of single particles and / or quasi-single particles have higher particle strength than existing lithium nickel-based oxides in the form of secondary particles, which are composed of agglomerates of tens to hundreds of primary particles, and therefore suffer less particle cracking during rolling.

[0034] In addition, in the case of the lithium nickel-based oxide in the form of a single particle or quasi-single particle according to the present invention, the number of lower-component elements (i.e., nodules) constituting the particle is small, so there is little change due to volume expansion and contraction of the primary particles during charge and discharge, and therefore the occurrence of cracks inside the particles is significantly reduced.

[0035] In particular, the inventors of the present invention have found that when a cathode active material having a negative skewness factor (NSF) represented by the following formula 1 that satisfies a predetermined range is used, particle cracking is minimized during the electrode manufacturing process, resulting in less gas generation, changes in crystalline structure during charge and discharge are minimized, and the diffusion distance of lithium ions within particles is reduced, resulting in low initial resistance characteristics, and the tap density and pellet density are maximized, thereby improving energy density.

[0036] [Formula 1] NSF=(D 50 -D 10 ) / I max

[0037] In the formula 1, D 50 is the particle size at the point where the cumulative volume is 50% in the volume cumulative particle size distribution graph of the positive electrode active material, and D 10 is the particle size at the point where the cumulative distribution is 10% in the volume cumulative particle size distribution graph of the positive electrode active material, and Imax is the maximum volume fraction in the volume cumulative particle size distribution graph of the positive electrode active material.

[0038] The positive electrode active material according to the present invention may include a lithium nickel-based oxide in which the molar ratio of Ni to the total transition metals is 60 mol % or more, 70 mol % or more, or 80 mol % or more.

[0039] The positive electrode active material according to the present invention may have an NSF value of 0.20 to 0.35, 0.21 to 0.35, or 0.21 to 0.34. Research by the present inventors has shown that when the NSF value is less than 0.20 or exceeds 0.35, the tap density and pellet density decrease.

[0040] When the NSF value is within the above range, the spaces between the relatively large particles are filled by the small particles, resulting in an increase in tap density and pellet density. When the NSF value is less than 0.20, there are not enough small particles to fill the spaces between the large particles, and when the NSF value is more than 0.35, the small particles remain even after filling the spaces between the large particles, resulting in a decrease in pellet density. Therefore, D 50 Even if the NSF value is the same, the tap density and pellet density can be maximized by optimizing the NSF value.

[0041] The positive electrode active material according to the present invention is D 50 The diameter D of the positive electrode active material according to the present invention can be 5.0 μm to 7.0 μm, 5.5 μm to 6.5 μm, or 5.6 μm to 6.2 μm. 50 When the NSF value is the same, the D of the positive electrode active material is 50 The larger the D of the positive electrode active material, the higher the pellet density. 50 If the diameter is less than 5.0 μm, even if the optimum level of NSF is achieved, it may be difficult to achieve a relatively high pellet density. 50 If the particle size exceeds 7.0 μm, the lithium mobility in the positive electrode active material decreases, and the initial resistance of a lithium secondary battery containing the same may increase.

[0042] Meanwhile, the positive electrode active material according to the present invention may include a lithium nickel-based oxide, specifically, a lithium nickel-based oxide having a composition represented by the following Chemical Formula 1:

[0043] [Chemical formula 1] Li a Ni b Co c M 1 d M 2 e O2

[0044] In the above Chemical Formula 1, M 1 is Mn, Al or a combination thereof, preferably Mn or a combination of Mn and Al, and M 2 is one or more elements selected from the group consisting of Ba, Ca, Zr, Ti, Mg, Ta, Nb and Mo. 2 Although the elements are not essential, when contained in an appropriate amount, they can promote grain growth during firing or improve the stability of the crystal structure.

[0045] The a represents the molar ratio of lithium in the lithium nickel-based oxide and may be 1.0≦a≦1.5, 1.1≦a≦1.4, or 1.2≦a≦1.3. When the lithium molar ratio satisfies this range, a stable layered crystal structure can be formed.

[0046] The b represents the molar ratio of nickel to all metals other than lithium in the lithium nickel-based oxide, and may be 0.6≦b<1.0, 0.8≦b<1.0, or 0.82≦b<1.0. When the nickel molar ratio satisfies this range, excellent capacity characteristics can be achieved, and particularly, when the nickel molar ratio is 0.8 or more, even better capacity characteristics can be achieved.

[0047] The c represents the molar ratio of cobalt to all metals other than lithium in the lithium nickel-based oxide, and is 0 <c<0.1、0<c<0.08、または0<c<0.06であることができる。

[0048] The d is M among all metals other than lithium in the lithium nickel-based oxide. 1 indicates the molar ratio of 0 <d<0.2、0<d<0.18、または0<d<0.15であることができる。

[0049] The e is M among all metals other than lithium in the lithium nickel-based oxide. 2 It denotes the molar ratio of the elements and can be 0≦e≦0.1, 0≦e≦0.08, or 0≦e≦0.06.

[0050] The cathode active material according to the present invention may have an average nodule particle size of 1.0 μm to 7.0 μm, 2.0 μm to 6.0 μm, or 3.0 μm to 5.0 μm. When the average nodule particle size of the cathode active material according to the present invention is within this range, high energy density and low initial resistance characteristics can be achieved. If the average nodule particle size of the cathode active material according to the present invention is less than 1.0 μm, the overall specific surface area of ​​the cathode active material may increase, which may increase side reactions in the electrolyte. If the average nodule particle size is more than 7.0 μm, the lithium mobility in the cathode active material may decrease, which may degrade the battery output characteristics.

[0051] The positive electrode active material according to the present invention may have a tap density of 2.40 g / cc to 2.60 g / cc, 2.42 g / cc to 2.56 g / cc, or 2.43 g / cc to 2.54 g / cc. When the tap density of the positive electrode active material according to the present invention satisfies the above range, a high energy density can be achieved.

[0052] The positive electrode active material according to the present invention may have a pellet density (9 ton) of 3.60 g / cc to 3.80 g / cc or more, 3.61 g / cc to 3.78 g / cc, or 3.62 g / cc to 3.75 g / cc. When the pellet density of the positive electrode active material according to the present invention satisfies this range, a high energy density can be achieved.

[0053] Meanwhile, the initial resistance at SOC50 of a mono-cell manufactured using the positive electrode active material may be 1.45Ω to 1.50Ω, preferably 1.47Ω to 1.50Ω, and more preferably 1.48Ω to 1.49Ω.

[0054] Method for producing positive electrode active material Next, a method for producing the positive electrode active material of the present invention will be described.

[0055] The method for producing a positive electrode active material according to the present invention includes the steps of (A) mixing a positive electrode active material precursor and a lithium source material and performing primary firing, and (B) pulverizing the primary fired material and performing secondary firing.

[0056] The produced positive electrode active material includes a single particle consisting of one single nodule, a quasi-single particle which is a composite of 30 or less nodules, or a combination thereof, and includes a lithium nickel-based oxide in which the molar ratio of Ni among all transition metals is 60 mol % or more, and has a negative skewness factor (NSF) represented by the following formula 1 of 0.20 to 0.35.

[0057] [Formula 1] NSF=(D 50 -D 10 ) / I max

[0058] In the formula 1, D 50 is the particle size at the point where the cumulative volume is 50% in the volume cumulative particle size distribution graph of the positive electrode active material, and D 10 is the particle size at the point where the cumulative distribution is 10% in the volume cumulative particle size distribution graph of the positive electrode active material, and I maxis the maximum volume fraction in the volume cumulative particle size distribution graph of the positive electrode active material.

[0059] The above-mentioned content is similarly applied to the formula 1, so a duplicated explanation will be omitted.

[0060] Each step of the method for producing a positive electrode active material will be specifically described below.

[0061] First, a positive electrode active material precursor and a lithium raw material are mixed together and then subjected to primary firing (step (A)).

[0062] Here, the positive electrode active material precursor may be a commercially available precursor such as nickel-cobalt-manganese hydroxide, or may be prepared by a precursor preparation method well known in the art, such as a coprecipitation method.

[0063] For example, nickel (Ni), cobalt (Co) and M 1 After preparing a transition metal-containing solution containing the cations, an ammonium cation-containing complex-forming agent and a basic aqueous solution are added to the transition metal-containing solution to cause a coprecipitation reaction, thereby preparing a positive electrode active material precursor.

[0064] The transition metal-containing solution contains a nickel-containing source material, a cobalt-containing source material, M 1 The raw material may be contained, and the M 1 The containing source material can be a manganese-containing source material and / or an aluminum-containing source material.

[0065] The nickel-containing source material may be, for example, a nickel-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically may be, but is not limited to, Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, NiSO4, NiSO4·6H2O, a fatty acid nickel salt, a nickel halide, or a combination thereof.

[0066] The cobalt-containing source material may be a cobalt-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically may be, but is not limited to, Co(OH)2, CoOOH, Co(OCOCH3)2·4H2O, Co(NO3)2·6H2O, CoSO4, Co(SO4)2·7H2O, or a combination thereof.

[0067] The manganese-containing source material may be, for example, a manganese-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof. Specifically, the manganese-containing source material may be, but is not limited to, manganese oxides such as MnO, MnO, MnO, etc.; manganese salts such as MnCO, Mn(NO), MnSO, ​​manganese acetate, manganese dicarboxylate, manganese citrate, and manganese fatty acid salt; manganese oxyhydroxide, manganese chloride, or a combination thereof.

[0068] The aluminum-containing source material can be, for example, Al2O3, Al(OH)3, Al(NO3)3, Al2(SO4)3, (HO)2AlCH3CO2, HOAl(CH3CO2)2, Al(CH3CO2)3 aluminum halide, or combinations thereof.

[0069] The transition metal-containing solution contains a nickel-containing source material, a cobalt-containing source material, and M 1 The nickel-containing raw material is added to a solvent, specifically, a mixed solvent of water or an organic solvent (e.g., alcohol) that can be uniformly mixed with water, or an aqueous solution of a nickel-containing raw material, an aqueous solution of a cobalt-containing raw material, and M 1 It can be produced by mixing the raw materials involved.

[0070] The ammonium cation-containing complexing agent may be, for example, but not limited to, NHOH, (NH)SO, NHNO, NHCl, CHCOONH, NHCO, or a combination thereof. Meanwhile, the ammonium cation-containing complexing agent may be used in the form of an aqueous solution, in which the solvent may be water or a mixture of water and an organic solvent (e.g., alcohol) that is uniformly miscible with water.

[0071] The basic compound may be a hydroxide of an alkali metal or alkaline earth metal, such as NaOH, KOH, or Ca(OH), a hydrate thereof, or a combination thereof. The basic compound may also be used in the form of an aqueous solution, and the solvent may be water or a mixture of water and an organic solvent (e.g., alcohol) that is uniformly miscible with water.

[0072] The basic compound is added to adjust the pH of the reaction solution, and can be added in an amount that makes the pH of the metal solution 8 to 12.

[0073] The co-precipitation reaction can be carried out in an inert atmosphere such as nitrogen or argon at a temperature range of 35°C to 80°C.

[0074] By the above process, nickel-cobalt-M 1 The hydroxide positive electrode active material precursor particles are generated and precipitated in the reaction solution. 1 By adjusting the concentrations of the raw materials contained, a cathode active material precursor having a nickel (Ni) content of 60 mol% or more based on the total metal content can be produced. The precipitated cathode active material precursor particles can be separated and dried using a conventional method to produce the cathode active material precursor.

[0075] Meanwhile, the cathode active material precursor prepared as described above was 50The diameter of the positive electrode active material precursor may be 4.0 μm to 10.0 μm, preferably 5.0 μm to 9.0 μm, and more preferably 6.0 μm to 8.0 μm. 50 When the thickness is less than 4.0 μm, the D 50 is likely to be smaller than the appropriate range, and the D 50 If the particle size exceeds 10.0 μm, the specific surface area (BET) decreases, which may reduce the reactivity when mixed with the lithium source material, and may reduce the structural integrity of the positive electrode active material.

[0076] The positive electrode active material precursor and the lithium source material can then be mixed.

[0077] The lithium source material may be a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, and is not particularly limited as long as it is soluble in water. Specifically, the lithium source material may be Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, or Li3C6H5O7, or a mixture of two or more thereof.

[0078] The positive electrode active material precursor and the lithium source material may be mixed in a molar ratio of, for example, but not limited to, about 1:1, about 1:1.05, about 1:1.10, about 1:1.15, or about 1:1.20.

[0079] The mixture can then be first fired.

[0080] The primary firing can be carried out in an air or oxygen atmosphere.

[0081] The primary firing can be carried out at a temperature of 700°C to 1000°C, 800°C to 900°C, or 825°C to 875°C.

[0082] The primary firing can be carried out for 6 to 18 hours, 8 to 16 hours, or 10 to 14 hours.

[0083] Next, the primary fired product is pulverized and then subjected to secondary firing (step (B)).

[0084] Here, the pulverization can be performed, for example, by jet mill pulverization, and the jet mill pulverization can be performed at a pressure range of 2.0 bar to 4.0 bar, 2.2 bar to 3.8 bar, or 2.4 bar to 3.5 bar.

[0085] Jet-mill grinding can also be carried out at a speed range of 1000 rpm to 2500 rpm, 1200 rpm to 2400 rpm, or 1300 rpm to 2300 rpm. The positive electrode active material produced by grinding within the above range of speed may have an NSF value of 0.20 to 0.35, 0.21 to 0.35, or 0.21 to 0.34, thereby achieving low initial resistance and high energy density.

[0086] The jet-mill grinding can improve the structural integrity of the surface exposed by cracking the particles.

[0087] The secondary firing can be carried out at a temperature of 500 to 1000°C, 600 to 900°C, or 700 to 800°C.

[0088] The secondary firing can be carried out for 6 to 18 hours, 8 to 16 hours, or 10 to 14 hours.

[0089] The recrystallization reaction caused by the secondary firing can improve the structural integrity of the positive electrode active material compared to after the primary firing.

[0090] After the jet-mill grinding, secondary firing can recrystallize the surface exposed by cracking of the particles and remove fine powder in the process.

[0091] On the other hand, M 2 When preparing a lithium composite transition metal oxide containing a metal, M 2 A metal-containing raw material can be further mixed. 2 Metal-containing raw materials are 2 It can be a metal acetate, carbonate, nitrate, sulfate, halide, sulfide, or oxide, or the like.

[0092] positive electrode A positive electrode according to the present invention includes the above-described positive electrode active material of the present invention. Specifically, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer includes the positive electrode active material of the present invention. 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.

[0093] The positive electrode current collector may include a highly conductive metal, and is not particularly limited as long as it is easily adhered to the positive electrode active material layer and is non-reactive within the battery voltage range. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, heat-treated carbon, and aluminum or stainless steel whose surfaces are surface-treated with carbon, nickel, titanium, silver, etc. The positive electrode current collector typically has a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the current collector to enhance the adhesion of the positive electrode active material. The positive electrode current collector may be used in various forms, such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0094] The positive electrode active material layer may optionally contain a conductive material and a binder in addition to the positive electrode active material, as required.

[0095] Here, the positive electrode active material may be included in an amount of 80 wt % to 99 wt %, more specifically, 90 wt % to 98 wt %, based on the total weight of the positive electrode active material layer.

[0096] The conductive material is used to impart conductivity to the electrode. Any conductive material can be used without particular limitations, as long as it does not cause chemical changes in the resulting battery and has electronic conductivity. Specific examples include graphite, such as natural graphite or artificial graphite; carbon-based materials, such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or fibers, such as copper, nickel, aluminum, and silver; conductive tubes, such as carbon nanotubes; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and conductive polymers, such as polyphenylene derivatives. These materials can be used alone or in combination. The conductive material can be present in an amount of 0.01 wt % to 10 wt %, preferably 0.1 wt % to 9 wt %, and more preferably 0.1 wt % to 5 wt %, based on the total weight of the positive electrode active material layer.

[0097] The binder improves adhesion between positive electrode active material particles and between the positive electrode active material and the current collector. Specific examples of the binder include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, polymers in which hydrogen is substituted with Li, Na, or Ca, or various copolymers thereof. These may be used alone or in combination. The binder can be contained in an amount of 1 to 30% by weight, preferably 1 to 20% by weight, and more preferably 1 to 10% by weight, based on the total weight of the positive electrode active material layer.

[0098] The positive electrode can be manufactured by a conventional method for manufacturing a positive electrode, except for using the positive electrode active material. Specifically, the positive electrode can be manufactured by dissolving or dispersing the positive electrode active material and, optionally, a binder, a conductive material, and a dispersant in a solvent to prepare a positive electrode slurry composition, which is then coated on a positive electrode current collector, followed by drying and rolling.

[0099] The solvent may be a solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water, and may be used alone or in combination. The amount of the solvent used may be sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant, taking into consideration the coating thickness of the slurry and the manufacturing yield, and to provide a viscosity that allows excellent thickness uniformity during subsequent coating for manufacturing a positive electrode.

[0100] Alternatively, the positive electrode can be produced by casting the positive electrode slurry composition on a separate support, peeling the composition from the support, and laminating the resulting film on a positive electrode current collector.

[0101] Lithium secondary battery Next, the lithium secondary battery according to the present invention will be described.

[0102] Specifically, the lithium secondary battery includes a positive electrode, a negative electrode facing the positive electrode, and a separator and an electrolyte interposed between the positive electrode and the negative electrode. Since the positive electrode is as described above, a detailed description thereof will be omitted, and only the remaining components will be described in detail below.

[0103] The lithium secondary battery may 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.

[0104] In the lithium secondary battery, the negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0105] The negative electrode current collector may be any material that does not cause chemical changes in the battery and has high conductivity, and examples of such materials include copper, stainless steel, aluminum, nickel, titanium, heat-treated carbon, copper or stainless steel surfaces treated with carbon, nickel, titanium, silver, or the like, and aluminum-cadmium alloys. The negative electrode current collector typically has a thickness of 3 μm to 500 μm. As with the positive electrode current collector, the current collector may have fine irregularities on its surface to enhance the binding strength of the negative electrode active material. The negative electrode current collector may be used in various forms, such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0106] The negative electrode active material layer may optionally contain a binder and a conductive material in addition to the negative electrode active material.

[0107] The negative electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium. Specific examples thereof include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, and Al alloys; and SiO. βExamples of the negative electrode active material include metal oxides capable of doping and dedoping lithium, such as SnO2, vanadium oxide, and lithium vanadium oxide (0<β<2); and composites containing the metallic compounds and carbonaceous materials, such as Si-C composites and Sn-C composites. These may be used alone or in combination. A thin film of metallic lithium may also be used as the negative electrode active material. The carbon material may be either low-crystalline carbon or high-crystalline carbon. Typical low-crystalline carbons are soft carbon and hard carbon, while typical high-crystalline carbons are amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature heat-treated carbons such as petroleum or coal tar pitch-derived cokes.

[0108] The negative electrode active material may be included in an amount of 80% by weight to 99% by weight, 82% by weight to 99% by weight, or 84% by weight to 99% by weight based on the total weight of the negative electrode active material layer.

[0109] The binder is a component that helps bind the conductive material, active material, and current collector together, and is typically added in an amount of 0.1 to 10% by weight based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0110] The conductive material is a component for further improving the conductivity of the negative electrode active material and may be included in an amount of 1 wt % to 30 wt %, 1 wt % to 20 wt %, or 1 wt % to 10 wt % based on the total weight of the negative electrode active material layer. The conductive material is not particularly limited as long as it does not cause chemical changes in the battery and has conductivity. Examples of the conductive material include graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; carbon fluoride; metal powder such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0111] The negative electrode active material layer may be prepared by coating a negative electrode slurry composition, which is 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 and drying the coating. Alternatively, the negative electrode slurry composition may be cast on a separate support, peeled from the support, and the resulting film may be laminated on the negative electrode current collector.

[0112] Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a path for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without particular limitations. In particular, a separator that exhibits low resistance to electrolyte ion movement and excellent electrolyte humidification capability is preferred. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof can be used. Conventional porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, can also be used. To ensure heat resistance or mechanical strength, a separator coated with a ceramic component or a polymer material can also be used, and can be selectively used in a single-layer or multi-layer structure.

[0113] Furthermore, examples of the electrolyte used in the present invention include 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 production of lithium secondary batteries, but are not limited to these.

[0114] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0115] The organic solvent may be any solvent that can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether and tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate. Examples of solvents that can be used include carbonate-based solvents such as ethylene carbonate (PC), alcohol-based solvents such as ethyl alcohol and isopropyl alcohol, nitriles such as R-CN (where R is a hydrocarbon group having 2 to 20 carbon atoms and having a linear, branched, or cyclic structure, and may contain a double-bonded aromatic ring or an ether bond), amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, and sulfolanes. Among these, carbonate-based solvents are preferred, and mixtures of cyclic carbonates (e.g., ethylene carbonate or propylene carbonate) with high ionic conductivity and a high dielectric constant, which can improve the charge / discharge performance of batteries, and low-viscosity linear carbonate compounds (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) are more preferred.

[0116] The lithium salt can be any compound that can provide lithium ions used in lithium secondary batteries without any particular limitations. Specifically, the anion of the lithium salt can be F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The lithium salt may be at least one selected from the group consisting of: LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably within a range of 0.1M to 4.0M, preferably 0.5M to 3.0M, and more preferably 1.0M to 2.0M. When the lithium salt concentration is within this range, the electrolyte has appropriate conductivity and viscosity, thereby exhibiting excellent electrolyte performance and allowing lithium ions to migrate effectively.

[0117] In addition to the electrolyte components, the electrolyte may further contain one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethyl alcohol amine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinoneimine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethyl alcohol, or aluminum trichloride, for the purposes of improving battery life characteristics, suppressing battery capacity loss, and improving battery discharge capacity. Here, the additives may be contained in an amount of 0.1 to 10.0 wt % based on the total weight of the electrolyte.

[0118] As described above, the lithium secondary battery including the cathode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, and is therefore useful in portable devices such as mobile phones, notebook computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0119] Therefore, according to another embodiment of the present invention, there is provided a battery module including the lithium secondary battery as a unit cell, and a battery pack including the same.

[0120] The battery module or battery pack may be used as a power source for one or more medium- to large-sized devices, such as power tools; electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems.

[0121] Although the present invention may be embodied in many different forms, it is not intended to be limited to the embodiments set forth herein, and the present invention may be practiced in various different forms, without departing from the spirit or scope of the present invention.

[0122] Examples and Comparative Examples Example 1 D 50 Positive electrode active material precursor Ni 0.90 Co 0.05 Mn 0.05 (OH)2 and the lithium source material LiOH were mixed and then subjected to primary firing at 850°C for 12 hours.

[0123] Next, the primary fired material was jet-milled under conditions of 2.5 bar and 1400 rpm for 1 hour, and then secondary fired at 750°C for 12 hours to obtain the positive electrode active material LiNi 0.90 Co 0.05 Mn 0.05 (OH)2 was produced.

[0124] Example 2 D 50 A positive electrode active material was produced in the same manner as in Example 1, except that a positive electrode active material precursor having a particle size of 8.0 μm was used and jet-milled at 2.5 bar and 1800 rpm for 1 hour.

[0125] Example 3 D 50 A positive electrode active material was produced in the same manner as in Example 1, except that a positive electrode active material precursor having a particle size of 9.0 μm was used and jet-milled at 2.5 bar and 2400 rpm for 1 hour.

[0126] Example 4 D 50 A positive electrode active material was produced in the same manner as in Example 1, except that a positive electrode active material precursor having a particle size of 9.0 μm was used and jet-milled at 3.0 bar and 2400 rpm for 1 hour.

[0127] Comparative Example 1 D 50 A positive electrode active material was produced in the same manner as in Example 1, except that a positive electrode active material precursor having a particle size of 3.5 μm was used and jet-milled at 2.5 bar and 800 rpm for 1 hour.

[0128] Comparative Example 2 D 50 A positive electrode active material was produced in the same manner as in Example 1, except that a positive electrode active material precursor having a particle size of 5.5 μm was used and jet-milled at 2.5 bar and 800 rpm for 1 hour.

[0129] Comparative Example 3 D 50 A positive electrode active material was produced in the same manner as in Example 1, except that a positive electrode active material precursor having a particle size of 7.0 μm was used and pulverized in a jet mill under conditions of 2.5 bar and 800 rpm for 1 hour.

[0130] Comparative Example 4 D 50 A positive electrode active material was produced in the same manner as in Example 1, except that a positive electrode active material precursor having a particle size of 9.0 μm was used and jet-milled at 2.5 bar and 2800 rpm for 1 hour.

[0131] Experimental Example 1: Particle size distribution of positive electrode active material 0.005 g of each of the positive electrode active materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 was dispersed in a dispersion medium HO, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000). Ultrasonic waves of about 28 kHz were irradiated at an output of 60 W to obtain a volume cumulative particle size distribution graph for each positive electrode active material. Using the graph, 50 , D 10 , I max and the NSF value was calculated using the following formula 1.

[0132] [Formula 1] NSF=(D 50 -D 10 ) / I max

[0133] In the formula 1, D 50 is the particle size at the point where the cumulative volume is 50% in the volume cumulative particle size distribution graph of the positive electrode active material, and D 10 is the particle size at the point where the cumulative distribution is 10% in the volume cumulative particle size distribution graph of the positive electrode active material, and I max is the maximum volume fraction in the volume cumulative particle size distribution graph of the positive electrode active material.

[0134] The volume cumulative particle size distribution graph of each positive electrode active material is shown in Figure 1. 50 , D 10 , I max The NSF values ​​of the following formula 1 are shown in Table 1 below.

[0135] [Table 1]

[0136] Experimental Example 2: Tap density and pellet density of positive electrode active material Using a tap density tester (Micromeritics GeoPyc 1365), the tap density of each of the positive electrode active materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 was measured. Specifically, 10 g of each of the positive electrode active materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 was filled into a 45 cc container, and the container was vibrated horizontally until a force of 108 N was applied to measure the tap density. The measurement results are shown in Table 2 below. 50 The tap density is shown in FIG.

[0137] Using a density measuring machine (Caver Pellet Press), the pellet density of each of the positive electrode active materials produced in Examples 1 to 4 and Comparative Examples 1 to 4 was measured. Specifically, 5 g of each of the positive electrode active materials produced in Examples 1 to 4 and Comparative Examples 1 to 4 was divided into small portions, tightly packed into a cylindrical holder with a diameter of 13 mm, and then a pressure of 9 tons was applied to measure the pellet density. The measurement results are shown in Table 2 below. 50 The pellet density according to the NSF value is shown in FIG. 3, and the pellet density according to the NSF value is shown in FIG.

[0138] [Table 2]

[0139] From Table 2 above, it was found that the positive electrode active materials of Examples 1 to 4 had higher tap densities and higher pellet densities than the positive electrode active materials of Comparative Examples 1 to 4. From Figures 2 and 3, D 50 It was found that even when positive electrode active materials have the same NSF value, they have high tap density and high pellet density when the NSF value falls within the range specified in the examples of the present invention. In this case, it is believed that the spaces between the relatively large particles are filled by small particles, resulting in increased tap density and pellet density. On the other hand, in Comparative Examples 1 to 3, where the NSF value is less than 0.20, there are insufficient small particles to fill the spaces between the large particles. In Comparative Example 4, where the NSF value is greater than 0.35, it is believed that even after the small particles have filled the spaces between the large particles, some small particles remain, resulting in a decrease in pellet density.

[0140] Experimental Example 3: Initial resistance of lithium secondary battery <Lithium secondary battery manufacturing> The positive electrode active materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4, respectively, a conductive material (Carbon Black, Denka), and a PVDF binder were mixed in N-methylpyrrolidone at a weight ratio of 96:1:3 to prepare a positive electrode slurry. The positive electrode slurry was applied to one side of an aluminum current collector, dried at 130°C, and rolled to prepare a positive electrode.

[0141] The negative electrode active material, binder, and conductive material were mixed in N-methylpyrrolidone in a weight ratio of 97:1.5:1.5 to prepare a negative electrode mixture. Specifically, artificial graphite was used as the negative electrode active material, carboxymethyl cellulose (CMC) as the binder, and carbon black as the conductive material. The negative electrode mixture was applied to one side of a copper current collector, dried at 110°C, and then rolled to prepare a negative electrode.

[0142] An electrode assembly was fabricated by interposing a separator between the positive and negative electrodes, and then placed inside a battery case. An electrolyte solution was then injected into the case to fabricate a battery cell. The electrolyte solution was prepared by dissolving 1M LiPF6 in a mixed organic solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of 1:1:1, and adding 5 wt% vinylene carbonate (VC).

[0143] The initial resistance was measured by measuring the change in voltage when a current of 2.5C was applied to the fabricated battery cell for 10 seconds at SOC50 (half-charged battery state). The measurement results are shown in Table 3 below and Figure 5.

[0144] [Table 3]

[0145] According to Table 3 and Figure 5, the NSF value is 0.18, and D 50 It was found that the positive electrode active material of Comparative Example 3, in which the particle size was greater than 7.0 μm, had a higher initial resistance value than the positive electrode active materials of Examples 1 to 4. This is believed to be because the diffusion distance of lithium ions within the particles in the positive electrode active material increases, reducing lithium mobility and increasing the initial resistance of a lithium secondary battery containing the positive electrode active material. Referring to Experimental Examples 2 and 3, it was found that the positive electrode active material of the present invention maximizes tap density and pellet density, increases energy density, and has low initial resistance characteristics.

Claims

1. A positive electrode active material comprising a single particle consisting of one single nodule, a pseudo-single particle which is a composite of 30 or less nodules, or a combination thereof, The positive electrode active material includes a lithium nickel-based oxide in which the molar ratio of Ni to all transition metals is 60 mol % or more, The negative strain factor (NSF) represented by the following formula 1 is 0.20 to 0.35, [Formula 1] NSF=(D ５０ -D １０ ) / I ｍａｘ In the formula 1, D ５０ is the particle size at the point where the cumulative volume is 50% in the volume cumulative particle size distribution graph of the positive electrode active material, and D １０ is the particle size at a point where the cumulative distribution is 10% in the volume cumulative particle size distribution graph of the positive electrode active material, and I ｍａｘ is the maximum volume fraction in a volume cumulative particle size distribution graph of the positive electrode active material.

2. D of the positive electrode active material ５０ The positive electrode active material according to claim 1, wherein the average particle diameter is 5.0 μm to 7.0 μm.

3. The lithium nickel-based oxide is represented by the following chemical formula 1: [Chemical formula 1] Li ａ Ni ｂ Co ｃ M １ ｄ M ２ ｅ O ２ In the above formula 1, M １ is Mn, Al or a combination thereof, and M ２ is one or more elements selected from the group consisting of Ba, Ca, Zr, Ti, Mg, Ta, Nb, and Mo, and 1.0≦a≦1.5, 0.6≦b<1.0, 0<c<0.1, 0<d<0.2, 0≦e≦0.1, and 0<c+d+e≦0.

4.

4. 2. The positive electrode active material according to claim 1, wherein the average particle size of the nodules of the positive electrode active material is 1.0 μm to 7.0 μm.

5. 2. The positive electrode active material according to claim 1, wherein the tap density of the positive electrode active material is 2.40 g / cc to 2.60 g / cc.

6. 2. The positive electrode active material according to claim 1, wherein the pellet density of the positive electrode active material is 3.60 g / cc to 3.80 g / cc.

7. 2. The positive electrode active material according to claim 1, wherein the initial resistance of a mono-cell manufactured using the positive electrode active material at an SOC of 50% is 1.45Ω to 1.50Ω.

8. A method for producing the positive electrode active material according to any one of claims 1 to 7, comprising: (A) mixing a positive electrode active material precursor and a lithium source material and performing primary firing to obtain a primary fired product; (B) crushing the primary fired product and subjecting it to secondary firing.

9. D of the positive electrode active material precursor ５０ The method for producing a positive electrode active material according to claim 8, wherein the average particle size is 4.0 μm to 10.0 μm.

10. The method for producing a positive electrode active material according to claim 8 , wherein the pulverization is performed by jet mill pulverization.

11. The method for producing a positive electrode active material according to claim 10, wherein the jet mill pulverization is carried out under conditions of 2.0 bar to 4.0 bar and 1000 rpm to 2500 rpm.

12. A positive electrode comprising the positive electrode active material according to claim 1 .

13. A lithium secondary battery comprising the positive electrode according to claim 12.

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