Positive electrode active material, method for preparing same, and positive electrode and lithium secondary battery both comprising same

Abstract

The positive electrode active material according to the present invention is a positive electrode active material including a lithium nickel-based oxide in the form of a single particle consisting of one single nodule or a quasi-single particle which is a composite of 30 or fewer nodules, wherein the lithium nickel-based oxide includes cobalt (Co) and aluminum (Al) and the concentration ratios of cobalt (Co) and aluminum (Al) on the surface of the lithium-nickel-based oxide, as measured by energy dispersive X-ray spectroscopy (EDX), satisfy the following Equations 1 and 2, respectively: [Equation 1] (Co concentration ratio inside the nodule with respect to the positive electrode active material) ≤ (Co concentration ratio at the nodule interface with respect to the positive electrode active material) ≤ (Co concentration ratio at the surface of the lithium-nickel-based oxide particles with respect to the positive electrode active material) [Equation 2] (Al concentration ratio at the surface of the lithium-nickel-based oxide particles with respect to the positive electrode active material) ≤ (Al concentration ratio at the nodule interface with respect to the cathode active material) < (Al concentration ratio inside the nodule with respect to the cathode active material)

Description

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

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0039388, filed March 21, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a single particle type positive electrode active material having excellent high temperature life characteristics, a method for producing the same, and a positive electrode and a lithium secondary battery including the same.

[0005]

[0006] A lithium secondary battery is generally composed of a positive electrode, a negative electrode, a separator, and an electrolyte, and the positive electrode and negative electrode include an active material capable of intercalating and deintercalating lithium ions.

[0007] Lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2 or LiMnO4, etc.), and lithium iron phosphate compound (LiFePO4) have been used as cathode 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 price of cobalt, which is the raw material, and its supply are unstable, making it difficult to commercially apply it to large-capacity batteries. Lithium nickel oxide has poor structural stability, making it difficult to achieve sufficient cycle life characteristics. Meanwhile, lithium manganese oxide has excellent stability but has the problem of poor capacity characteristics. Therefore, lithium composite transition metal oxides containing two or more transition metals have been developed to complement the problems of lithium transition metal oxides containing only Ni, Co, or Mn. Among these, lithium nickel cobalt manganese oxide containing Ni, Co, and Mn is widely used in the field of electric vehicle batteries.

[0008] Conventional lithium nickel cobalt manganese oxides are generally in the form of spherical secondary particles formed by agglomeration of tens to hundreds of primary particles. However, when lithium nickel cobalt manganese oxides formed in the form of secondary particles formed by agglomeration of many primary particles are used, there is a problem in that the primary particles are likely to break during the rolling process during the manufacture of the positive electrode, and cracks may occur inside the particles during the charge and discharge process. When the positive electrode active material particles break or crack, the contact area with the electrolyte increases, which increases gas generation and active material degradation due to side reactions with the electrolyte, and this causes problems in that the life characteristics are reduced.

[0009] To address the above issues, a technique has been proposed for producing single-particle cathode active materials rather than secondary particles by increasing the sintering temperature during the manufacture 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 less side reactions with the electrolyte. Furthermore, their superior particle strength reduces particle breakage during electrode manufacture. Therefore, single-particle cathode active materials offer the advantages of superior gas generation and cycle life. However, conventional single-particle cathode active materials require high sintering temperatures during synthesis, which causes the crystal structure of the particle surface to change from a layered structure to a rock-salt structure. The non-conductive rock-salt surface impedes the movement of lithium ions during charge and discharge, thereby reducing the lifespan of the battery.

[0010]

[0011] The present invention is intended to solve the above problems, and to provide a positive electrode active material capable of suppressing degradation of the positive electrode active material during a charge / discharge process by including a coating layer containing cobalt and aluminum.

[0012] In addition, the present invention seeks to provide a positive electrode and a lithium secondary battery having improved high-temperature life characteristics by including the positive electrode active material.

[0013]

[0014] [1] The present invention provides a cathode active material comprising a lithium nickel-based oxide in the form of a single particle consisting of one single nodule or a pseudo-single particle complex consisting of 30 or fewer nodules, wherein the lithium nickel-based oxide comprises cobalt (Co) and aluminum (Al), and the concentration ratio of cobalt (Co) and aluminum (Al) measured on the surface of the lithium nickel-based oxide by energy dispersive X-ray spectroscopy (EDX) satisfies the following equations 1 and 2, respectively.

[0015] [Formula 1]

[0016] (Co concentration ratio in the nodule for the positive electrode active material)≤(Co concentration ratio at the nodule interface for the positive electrode active material)≤(Co concentration ratio at the surface of the lithium nickel-based oxide particle for the positive electrode active material)

[0017] [Formula 2]

[0018] (Al concentration ratio on the surface of lithium nickel-based oxide particles for positive electrode active material)≤(Al concentration ratio at the nodule interface for positive electrode active material)<(Al concentration ratio in the nodule for positive electrode active material)

[0019] [2] The present invention provides a positive electrode active material, wherein, in the above [1], the Co concentration ratio in the nodule with respect to the positive electrode active material in the above formula 1 is less than 5 mol%.

[0020] [3] The present invention provides a positive electrode active material, wherein, in the above [1] or [2], the concentration ratio of Al in the nodule to the positive electrode active material in the above formula 1 is 0.2 mol% or more.

[0021] [4] The present invention provides a positive electrode active material, wherein in at least one of the above [1] to [3], the positive electrode active material includes a coating layer formed on the surface of the lithium nickel-based oxide, and the coating layer includes at least one member from the group consisting of Co, Al, Mg, Ti, V, Cr, Mn, Zr, Nb, W, and B.

[0022] [5] The present invention provides a positive electrode active material, wherein in at least one of the above [1] to [4], the lithium nickel-based oxide has a molar ratio of Ni of 55 mol% or more among all transition metals excluding lithium.

[0023] [6] The present invention provides a positive electrode active material, wherein in at least one of the above [1] to [5], the lithium nickel-based oxide has a composition represented by the following chemical formula 1.

[0024] [Chemical Formula 1]

[0025] Li a Ni b Co c M 1 d M 2 e O2

[0026] In the above chemical formula 1, M 1 At least one selected from the group consisting of Mn and Al, and M 2 is at least one selected from the group consisting of Ti, Mg, Zr, Y, Ba, Ca, Zr, Sr, W, Ta, Nb, and Mo, and 1.0≤a≤1.5, 0.55≤b<1.0, 0 <c≤0.20, 0<d≤0.20, 0≤e≤0.10임.

[0027] [7] The present invention provides a positive electrode active material, wherein, in at least one of the above [1] to [6], the average particle diameter of the nodules of the positive electrode active material is 1.0 µm to 10.0 µm.

[0028] [8] The present invention, in at least one of the above [1] to [7], D of the positive electrode active material 50 Provided is a positive electrode active material having a diameter of 2.0㎛ to 10.0㎛.

[0029] [9] The present invention, in at least one of the above [1] to [8], the positive electrode active material has a BET specific surface area of ​​0.2 m 2 / g to 1.5m 2 / g, a positive electrode active material is provided.

[0030]

[0010] The present invention provides a method for manufacturing a cathode active material, comprising: a step of forming a lithium nickel-based oxide by mixing a lithium nickel-based hydroxide precursor, a lithium raw material, and an aluminum-containing raw material, and then calcining the mixture; and a step of forming a coating layer by mixing two types of cobalt compounds and aluminum compounds of different sizes into the lithium nickel-based oxide, and then heat-treating the mixture.

[0031]

[0011] The present invention provides a method for manufacturing a positive electrode active material, wherein, in the above

[0010] , the calcination is performed at a temperature of 600°C to 1,000°C for 4 to 12 hours.

[0032]

[0012] In the present invention, in the above

[0010] or

[0011] , the cobalt compound is D 50 This 50 nm to 800 nm and D 50 A method for producing a positive electrode active material is provided, which comprises mixing two types of materials having a diameter of 200 nm to 2,000 nm in a ratio of 1:3 to 3:1.

[0033]

[0013] The present invention provides a method for producing a positive electrode active material, wherein, in at least one of the above

[0010] to

[0012] , the heat treatment is performed at a temperature of 600°C to 800°C for 4 to 12 hours.

[0034]

[0014] The present invention provides a method for producing a positive electrode active material, wherein, in at least one of the above

[0010] to

[0013] , mixing of the cobalt compound and the aluminum compound is performed by a dry mixing method.

[0035]

[0015] The present invention provides a positive electrode comprising a positive electrode active material according to any one of the above [1] to [9].

[0036]

[0016] The present invention provides a lithium secondary battery including a positive electrode according to the above

[0015] .

[0037]

[0038] In order to improve the problem that the high-temperature lifespan characteristics may be deteriorated when the Co concentration ratio in the nodule for the positive electrode active material decreases as charge and discharge progresses, the positive electrode active material according to the present invention has a cobalt (Co) and aluminum (Al) concentration ratio measured on the surface of a lithium nickel-based oxide using EDX so that it satisfies Equations 1 and 2, thereby increasing the overall material durability by strengthening the binding energy with oxygen, thereby suppressing the degradation of the positive electrode active material during the charge and discharge process of the battery, and thereby implementing excellent high-temperature lifespan characteristics.

[0039]

[0040] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0041] In the present invention, a "single particle" is a particle composed of one single nodule. In the present invention, a "quasi-single particle" means a composite particle formed of 30 or fewer nodules.

[0042] In the present invention, "nodule" means a sub-particle unit body constituting a single particle and a pseudo-single particle, and the nodule may be a single crystal lacking a crystalline grain boundary, or a polycrystal in which no grain boundary exists in appearance when observed under a field of view of 5000 to 20000 times using a scanning electron microscope (SEM). The average particle diameter of the nodule may be measured as the arithmetic mean value of the particle diameters of each nodule measured using a scanning electron microscope (SEM).

[0043] In the present invention, "secondary particle" refers to a particle formed by the aggregation of tens to hundreds, specifically more than 30, sub-particle unit bodies. To distinguish it from nodules, which are sub-particle units constituting single particles and pseudo-single particles, the sub-particle units constituting secondary particles are called "primary particles."

[0044] The expression "particle" used in the present invention may include any one or all of single particles, quasi-single particles, primary particles, nodules, and secondary particles.

[0045] In the present invention, "D 50 " means the particle size based on 50% of the volume cumulative particle size distribution of the positive electrode active material. The above D 50 can be measured using a laser diffraction method. For example, after dispersing the positive electrode active material powder in a dispersion medium, it can be measured by introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasonic waves of about 28 kHz at an output of 60 W, obtaining a volume cumulative particle size distribution graph, and then calculating the particle size corresponding to 50% of the volume cumulative amount.

[0046] In the present invention, the “specific surface area” is measured by the BET method, and specifically, can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using BELSORP-mino II of BEL Japan.

[0047] In the present invention, the concentration of specific atoms within the nodule, at the nodule interface, and on the surface of the lithium nickel oxide can be confirmed using "energy dispersive X-ray spectroscopy (EDX)". During EDX measurement, scanning and measuring within each area and evaluating the area in two dimensions is sometimes called EDX surface analysis, and extracting data of a line-shaped area from EDX surface analysis to evaluate the distribution within the positive electrode active material particle with respect to the atomic concentration is sometimes called line analysis.

[0048]

[0049] Hereinafter, the present invention will be described in detail.

[0050] The cathode active material, the method for producing the cathode active material, the cathode, and / or the lithium secondary battery according to the present invention comprise at least one of the following disclosed configurations, and may comprise any combination between technically possible configurations among the following configurations.

[0051]

[0052] positive electrode active material

[0053] Hereinafter, the positive electrode active material according to the present invention will be described.

[0054] The cathode active material according to the present invention is a cathode active material comprising a lithium nickel-based oxide in the form of a single particle consisting of one single nodule or a pseudo-single particle complex consisting of 30 or fewer nodules, wherein the lithium nickel-based oxide comprises cobalt (Co) and aluminum (Al).

[0055] The lithium nickel-based oxide particles are in the form of single particles consisting of one single nodule or pseudo-single particles consisting of a composite of 30 or fewer, preferably 2 to 20, and more preferably 2 to 10 nodules. Such lithium nickel-based oxide particles in the form of single particles and / or pseudo-single particles have higher particle strength than lithium nickel-based oxide particles in the form of existing secondary particles in which tens to hundreds of primary particles are aggregated, and thus particle breakage is reduced during rolling.

[0056] In addition, in the case of the lithium nickel-based oxide in the form of a single particle or pseudo-single particle according to the present invention, since the number of sub-particle units (i.e., nodules) constituting the particles is small, the change due to volume expansion and contraction of the primary particles during charge and discharge is small, and accordingly, the occurrence of cracks inside the particles is also significantly reduced.

[0057]

[0058] Meanwhile, the degradation of the positive electrode active material generally occurs due to a deterioration phenomenon at the interface between the electrolyte and the positive electrode active material. If the Co concentration ratio within the nodule to the positive electrode active material decreases, there is a problem that Li / Ni disordering within the nodule becomes more severe as charge and discharge progresses, and the stability of the layered structure deteriorates.

[0059] Accordingly, the inventors of the present invention confirmed that the high-temperature life characteristics are improved when the cobalt (Co) and aluminum (Al) concentration ratios measured on the surface of the lithium nickel-based oxide using energy dispersive X-ray spectroscopy (EDX) satisfy the following equations 1 and 2, respectively.

[0060] [Formula 1]

[0061] (Co concentration ratio in the nodule for the positive electrode active material)≤(Co concentration ratio at the nodule interface for the positive electrode active material)≤(Co concentration ratio at the surface of the lithium nickel-based oxide particle for the positive electrode active material)

[0062] [Formula 2]

[0063] (Al concentration ratio on the surface of lithium nickel-based oxide particles for positive electrode active material)≤(Al concentration ratio at the nodule interface for positive electrode active material)<(Al concentration ratio in the nodule for positive electrode active material)

[0064]

[0065] In the above equation 1, the Co concentration ratio within the nodule with respect to the positive active material may be less than 5 mol%, less than 3 mol%, or less than 1 mol%. In addition, the Co concentration ratio at the nodule interface with respect to the positive active material may be 5 mol% to 40 mol%, 10 mol% to 30 mol%, or 15 mol% to 25 mol%. In addition, the Co concentration ratio at the surface of the lithium nickel-based oxide particle with respect to the positive active material may be 10 mol% to 60 mol%, 20 mol% to 50 mol%, or 30 mol% to 40 mol%.

[0066]

[0067] In the above formula 2, the Al concentration ratio in the nodule with respect to the positive active material may be 0.2 mol% or more, 0.3 mol% to 5.0 mol%, or 1.0 mol% to 3.0 mol%. In addition, the Al concentration ratio at the nodule interface with respect to the positive active material may be 0.1 mol% to 2.0 mol%, 0.3 mol% to 1.5 mol%, or 0.5 mol% to 1.0 mol%. In addition, the Al concentration ratio at the surface of the lithium nickel-based oxide particle with respect to the positive active material may be 0.1 mol% to 2.0 mol%, 0.3 mol% to 1.5 mol%, or 0.5 mol% to 1.0 mol%.

[0068]

[0069] Meanwhile, the positive electrode active material according to the present invention includes a coating layer formed on the surface of the lithium nickel-based oxide.

[0070] Ni-based cathode active materials have a high capacity because the content of nickel among the transition metals that make up the cathode active material is higher than that of other transition metals, but there is unstable Ni present on the surface of the cathode active material. 3+ , Ni 4+ There is a limitation of structural instability due to ions. To address this structural instability, various technologies are being studied to modify the surface of the positive electrode active material.

[0071] The coating layer may include at least one selected from the group consisting of Co, Al, Mg, Ti, V, Cr, Mn, Zr, Nb, W, and B, and preferably may include Co and / or Al. In this case, the coating layer may include cobalt (Co) in an amount of 4,000 ppm to 25,000 ppm, preferably 8,000 ppm to 20,000 ppm, and more preferably 10,000 ppm to 15,000 ppm, based on the total weight of the positive electrode active material. In addition, the coating layer may include aluminum (Al) in an amount of 500 ppm to 12,000 ppm, preferably 1,000 ppm to 6,000 ppm, and more preferably 1,200 ppm to 3,000 ppm, based on the total weight of the positive electrode active material.

[0072]

[0073] Meanwhile, the cathode active material according to the present invention may have a composition in which the nickel content is 55 mol% or more, preferably 80 mol% or more, and more preferably 90 mol% or more among all metals excluding lithium. Specifically, it may include a lithium nickel-based oxide having a composition as shown in the following chemical formula 1.

[0074] [Chemical Formula 1]

[0075] Li a Ni b Co c M 1 d M 2 e O2

[0076] 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 at least one selected from the group consisting of Ba, Ca, Zr, Ti, Mg, Ta, Nb, and Mo. M 2 Although elements are not essential, when included in appropriate amounts, they can promote grain growth during firing or play a role in improving crystal structure stability.

[0077] The above a represents the molar ratio of lithium in the lithium nickel-based oxide, and may be 1.0≤a≤1.5, 1.0≤a≤1.2, or 1.00≤a≤1.15. When the molar ratio of lithium satisfies the above range, a stable layered crystal structure can be formed.

[0078] The above b represents the molar ratio of nickel among all metals excluding lithium in the lithium nickel-based oxide, and may be 0.55≤b<1.0, 0.80≤b<1.0, 0.85≤b<1.0, or 0.90≤b<1. When the molar ratio of nickel satisfies the above range, excellent capacity characteristics are exhibited, and in particular, when the molar ratio of nickel is 0.90 or more, even better capacity characteristics can be realized.

[0079] The above c represents the molar ratio of cobalt among all metals excluding lithium in the lithium nickel oxide, and is 0. <c≤0.20, 0<c<0.20, 또는 0<c<0.18일 수 있다.

[0080] The above d is M of all metals except lithium in lithium nickel oxide. 1 It represents the molar ratio of 0 <d≤0.20, 0<d<0.20, 또는 0<d<0.18일 수 있다.

[0081] The above e is M of all metals except lithium in lithium nickel oxide. 2It represents the molar ratio of elements, and can be 0≤e≤0.20, 0≤e≤0.15, or 0≤e≤0.10.

[0082]

[0083] The positive electrode active material according to the present invention may have an average particle size of nodules of 1.0 µm to 10.0 µm, 2.0 µm to 6.0 µm, or 3.0 µm to 5.0 µm. When the average particle size of the nodules of the positive electrode active material according to the present invention satisfies the above range, high energy density and low initial resistance characteristics can be realized. When the average particle size of the nodules of the positive electrode active material according to the present invention is less than 1.0 µm, the overall specific surface area of ​​the positive electrode active material may increase, which may increase electrolyte side reactions, and when the average particle size of the nodules exceeds 10.0 µm, lithium mobility in the positive electrode active material may decrease, which may deteriorate the output characteristics of the battery.

[0084]

[0085] The positive electrode active material according to the present invention is D 50 The D of the positive electrode active material according to the present invention may be 2.0 μm to 10.0 μm, 3.0 μm to 7.0 μm, or 3.5 μm to 5.0 μm. 50 When the above range is satisfied, high energy density and low initial resistance characteristics can be realized. D of the positive electrode active material 50 If it is less than 2.0㎛, it is difficult to implement high rolling density and the energy density may be low, and D 50 If it exceeds 10.0㎛, lithium mobility in the positive electrode active material may decrease, which may increase the initial resistance of the lithium secondary battery containing it.

[0086]

[0087] The positive electrode active material according to the present invention has a BET specific surface area of ​​0.2 m 2 / g to 1.5m 2 / g, preferably 0.3m 2 / g to 1.2m 2 / g or 0.4m 2 / g to 1.0m 2 / g, more preferably 0.4m 2 / g to 0.8m 2 / g. The BET specific surface area of ​​the positive electrode active material is 0.2 m 2 If it is less than / g, there is a concern about initial output reduction, and if the BET surface area is less than 1.5m 2 / g exceeds, there are concerns about high-temperature life, resistance increase rate, and storage gas. Therefore, if the BET specific surface area of ​​the positive electrode active material satisfies the above numerical range, excellent performance in terms of output performance and high-temperature durability can be realized.

[0088]

[0089] Method for manufacturing positive electrode active material

[0090] Next, a method for manufacturing the positive electrode active material of the present invention will be described.

[0091]

[0092] The method for manufacturing a cathode active material according to the present invention includes a step of mixing a lithium nickel-based hydroxide precursor, a lithium raw material, and an aluminum-containing raw material and then calcining them to form a lithium nickel-based oxide, and a step of mixing two types of cobalt compounds and aluminum compounds of different sizes into the lithium nickel-based oxide and then heat-treating them to form a coating layer.

[0093]

[0094] In addition, lithium nickel oxide is a single particle having a molar ratio of Ni of 55 mol% or more among the total transition metals, or a pseudo-single particle consisting of one single nodule or a composite of 30 or fewer nodules. Since the above explanation applies equally to this, a duplicate explanation is omitted.

[0095]

[0096] Hereafter, each step of the method for manufacturing a positive electrode active material is described in detail.

[0097]

[0098] First, a lithium nickel-based hydroxide precursor containing nickel, cobalt, and manganese, a lithium raw material, and an aluminum-containing raw material are mixed and then calcined to form a lithium nickel-based oxide.

[0099] At this time, the positive electrode active material precursor may be purchased and used as a commercially available precursor such as nickel-cobalt-manganese hydroxide, or may be manufactured according to a precursor manufacturing method known in the art, such as a co-precipitation method.

[0100] For example, nickel (Ni), cobalt (Co) and M 1 After preparing a transition metal-containing solution containing an ammonium cation, a complex forming agent containing an ammonium cation and a basic aqueous solution are added to the transition metal-containing solution to cause a co-precipitation reaction, thereby preparing a positive electrode active material precursor.

[0101] The above transition metal-containing solution contains nickel-containing raw materials, cobalt-containing raw materials, M 1 It may contain the raw material, and the above M 1 The containing raw material may be a manganese-containing raw material and / or an aluminum-containing raw material.

[0102] The nickel-containing raw 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, NiCO3ㆍ2Ni(OH)2ㆍ4H2O, NiC2O2ㆍ2H2O, Ni(NO3)2ㆍ6H2O, NiSO4, NiSO4ㆍ6H2O, fatty acid nickel salts, nickel halides or combinations thereof.

[0103] The cobalt-containing raw 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)2ㆍ4H2O, Co(NO3)2ㆍ6H2O, CoSO4, Co(SO4)2ㆍ7H2O or a combination thereof.

[0104] The manganese-containing raw material may be, for example, a manganese-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, oxyhydroxide or a combination thereof, and specifically, may be, but is not limited to, manganese oxides such as Mn2O3, MnO2, Mn3O4; manganese salts such as MnCO3, Mn(NO3)2, MnSO4, manganese acetate, manganese dicarboxylic acid salts, manganese citrate, manganese fatty acid salts; manganese oxyhydroxide, manganese chloride or a combination thereof.

[0105] The aluminum-containing raw material may be, for example, Al2O3, Al(OH)3, Al(NO3)3, Al2(SO4)3, (HO)2AlCH3CO2, HOAl(CH3CO2)2, Al(CH3CO2)3 aluminum halides or combinations thereof.

[0106] Transition metal containing solution contains nickel containing raw material, cobalt containing raw material and M 1 It is manufactured by adding the raw material containing nickel to a solvent, specifically, water, or a mixed solvent of an organic solvent (e.g., alcohol, etc.) that can be uniformly mixed with water, or an aqueous solution of a raw material containing nickel, an aqueous solution of a raw material containing cobalt, and M 1 It may be manufactured by mixing the raw materials contained therein.

[0107] The ammonium cation-containing complex forming agent may be, but is not limited to, NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, NH4CO3, or a combination thereof. Meanwhile, the ammonium cation-containing complex forming agent may be used in the form of an aqueous solution, and in this case, the solvent may be water, or a mixture of water and an organic solvent (specifically, alcohol, etc.) that can be uniformly mixed with water.

[0108] The basic compound may be a hydroxide of an alkali metal or alkaline earth metal, such as NaOH, KOH, or Ca(OH)2, a hydrate thereof, or a combination thereof. The basic compound may also be used in the form of an aqueous solution, in which case the solvent may be water, or a mixture of water and an organic solvent that is uniformly miscible with water (specifically, alcohol, etc.).

[0109] The basic compound is added to adjust the pH of the reaction solution, and can be added in an amount such that the pH of the metal solution becomes 8 to 12.

[0110] 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.

[0111] Nickel-cobalt-M by the above process 1 The positive electrode active material precursor particles of hydroxide are generated and precipitated in the reaction solution. Nickel-containing raw material, cobalt-containing raw material and M 1 By controlling the concentration of the contained raw material, a positive electrode active material precursor having a nickel (Ni) content of 55 mol% or more among the total metal content can be manufactured. The precipitated positive electrode active material precursor particles can be separated and dried according to a conventional method to manufacture a positive electrode active material precursor.

[0112]

[0113] Afterwards, the positive electrode active material precursor and the lithium raw material can be mixed.

[0114] The lithium raw material may include lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, and is not particularly limited as long as it can be dissolved in water. Specifically, the lithium raw material may be Li2CO3, LiNO3, LiNO2, LiOH, LiOHㆍH2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, or Li3C6H5O7, and any one of these or a mixture of two or more thereof may be used.

[0115] The cathode active material precursor and the lithium raw material may be mixed in a molar ratio of, for example, about 1:1, about 1:1.05, about 1:1.10, about 1:1.15, or about 1:1.20, but is not limited thereto.

[0116] The above aluminum-containing raw material can be mixed in an amount of 0.05 mol% to 4.0 mol%, preferably 0.1 mol% to 1.5 mol%, and more preferably 0.2 mol% to 1.0 mol%, based on the mole number of the positive electrode active material precursor.

[0117]

[0118] Thereafter, the mixture can be fired. The firing can be carried out in an air or oxygen atmosphere. The appropriate firing temperature can vary depending on the metal composition in the precursor. For example, when the nickel (Ni) content is 80 mol% or more, the firing temperature can be performed at a temperature of 600°C to 1000°C, 750°C to 950°C, or 800°C to 900°C. The firing can be performed for 4 hours to 12 hours, 6 hours to 12 hours, or 8 hours to 12 hours.

[0119] When the above-mentioned sintering temperature and time satisfy the above-mentioned range, the structural instability of the positive electrode active material due to the reduction in the Co content in the nodule that may occur as charge and discharge proceeds can be compensated for by the presence of Al in the nodule, and thus the high-temperature life characteristics can be improved.

[0120]

[0121] Next, two types of cobalt compounds and aluminum compounds of different sizes are mixed with the lithium nickel oxide and then heat-treated to form a coating layer.

[0122] The surface of the lithium nickel-based oxide particles is coated with a cobalt compound and an aluminum compound.

[0123] The above cobalt compound is D 50 This is 50 nm to 800 nm, preferably 100 nm to 500 nm, more preferably 150 nm to 350 nm, and D 50 It can be a mixture of two kinds of materials having a size of 200 nm to 2,000 nm, preferably 400 nm to 1,200 nm, and more preferably 600 nm to 900 nm. The two kinds of materials can be mixed in a ratio of 1:3 to 3:1. By using two kinds of cobalt compounds having different sizes, compared to when using a single cobalt compound, the Co concentration ratio at the nodule interface for the positive active material and the surface of the lithium nickel-based oxide particles for the positive active material can be selectively controlled, thereby maximizing the stability at the surface compared to the same Co content, thereby having the effect of improving high-temperature life performance.

[0124] The total mole number of the cobalt compound may be mixed in an amount of 0.5 mol% to 4.0 mol%, preferably 1.3 mol% to 3.3 mol%, and more preferably 1.6 mol% to 2.5 mol%, based on the mole number of the lithium nickel-based oxide. When the cobalt compound is mixed in an amount within the above numerical range, there is an effect of improving high-temperature life performance through a mechanism in which the Co coating reduces the Ni deterioration phenomenon at the interface between the electrolyte and the positive electrode active material.

[0125] The above cobalt compound may be a cobalt-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, and specifically, may be Co(OH)2, CoOOH, Co(OCOCH3)2ㆍ4H2O, Co(NO3)2ㆍ6H2O, CoSO4, Co(SO4)2ㆍ7H2O or a combination thereof, but is not limited thereto.

[0126] The above aluminum compound may be mixed in an amount of 0.03 mol% to 2.5 mol%, preferably 0.05 mol% to 1.0 mol%, and more preferably 0.1 mol% to 0.5 mol%, based on the mole number of lithium nickel-based oxide. When the above aluminum compound is mixed in an amount within the above numerical range, the high-temperature life performance is improved through the mechanism in which the Al coating reduces the Ni deterioration phenomenon at the interface between the electrolyte and the positive electrode active material.

[0127] The above aluminum compound may be, for example, Al2O3, Al(OH)3, Al(NO3)3, Al2(SO4)3, (HO)2AlCH3CO2, HOAl(CH3CO2)2, Al(CH3CO2)3 aluminum halide or a combination thereof.

[0128]

[0129] The heat treatment may be performed at a temperature of 600°C to 800°C, 650°C to 750°C, or 670°C to 730°C. The heat treatment may be performed for 4 hours to 12 hours, 6 hours to 12 hours, or 8 hours to 12 hours.

[0130] As a result of heat-treating a lithium nickel-based oxide mixed with a cobalt and aluminum compound within the above heat-treating temperature and heat-treating time range, Co and Al coating layers can be effectively formed on the nodule interface for the positive electrode active material and the surface of the lithium nickel-based oxide particles for the positive electrode active material, thereby effectively reducing the Ni deterioration phenomenon that mainly occurs at the interface with the electrolyte, thereby improving the high-temperature life characteristics.

[0131] The mixing of the above cobalt-containing raw material and aluminum-containing raw material can be performed by a dry mixing method.

[0132]

[0133] anode

[0134] The positive electrode according to the present invention comprises the positive electrode active material of the present invention described above. Specifically, the positive electrode comprises a positive electrode current collector, a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer comprises 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.

[0135]

[0136] The positive electrode current collector may include a highly conductive metal, and is not particularly limited as long as it is easily adhered to by the positive electrode active material layer and does not react within the voltage range of the battery. The positive electrode current collector may be made of, for example, stainless steel, aluminum, nickel, titanium, heat-treated carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. In addition, the positive electrode current collector may typically have a thickness of 3 μm to 500 μm, and fine unevenness may be formed on the surface of the current collector to increase the adhesion of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0137]

[0138] The above positive electrode active material layer may optionally include a conductive material and a binder, together with the positive electrode active material, as needed.

[0139] At this time, the positive electrode active material may be included in an amount of 80% to 99% by weight, more specifically 90% to 98% by weight, based on the total weight of the positive electrode active material layer.

[0140]

[0141] 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 particular limitation. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One of these may be used alone or a mixture of two or more may be used. The conductive material may be included in an amount of 0.01 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.

[0142]

[0143] The above binder serves to improve the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylalcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and polymers in which hydrogens of these are substituted with Li, Na, or Ca, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The above binder may be included in an amount of 1 wt% to 30 wt%, preferably 1 wt% to 20 wt%, and more preferably 1 wt% to 10 wt%, based on the total weight of the positive electrode active material layer.

[0144]

[0145] The above-mentioned positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the above-mentioned positive electrode active material is used. Specifically, the positive electrode slurry composition, prepared by dissolving or dispersing the above-mentioned positive electrode active material and optionally a binder, a conductive agent, and a dispersant in a solvent as needed, is applied onto a positive electrode current collector, followed by drying and rolling.

[0146] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethyl formamide (DMF), acetone, or water. One of these may be used alone or a mixture of two or more may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant in consideration of the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0147]

[0148] Alternatively, the positive electrode may be manufactured by casting the positive electrode slurry composition onto a separate support, peeling the resulting film from the support, and laminating the resulting film onto a positive electrode current collector.

[0149]

[0150] lithium secondary battery

[0151] Next, a lithium secondary battery according to the present invention will be described.

[0152]

[0153] 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 specifically described below.

[0154] 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.

[0155]

[0156] 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.

[0157] 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, heat-treated 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.

[0158]

[0159] The above negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0160] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. 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 alloy, Sn alloy, and Al alloy; metallic oxides capable of doping and dedoping lithium, such as SiOβ (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the 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 fibers, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature heat-treated carbon such as petroleum or coal tar pitch derived cokes.

[0161] The above negative electrode active material may be included in an amount of 80 wt% to 99 wt%, 82 wt% to 99 wt%, or 84 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0162]

[0163] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and is typically added in an amount of 0.1 wt% to 10 wt% based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0164]

[0165] The conductive agent 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 agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber or metal fiber; fluorinated carbon; metal powder such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0166]

[0167] The above negative electrode active material layer can be manufactured by applying and drying a negative electrode slurry composition 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 negative electrode slurry composition on a separate support, and then laminating the obtained film by peeling it off from the support on a negative electrode current collector.

[0168]

[0169] 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 any particular restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture absorption capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, 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.

[0170]

[0171] In addition, the electrolyte used in the present invention may include, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc. that can be used in the manufacture of a lithium secondary battery.

[0172] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0173] The organic solvent may be used without any particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent may include 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), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R represents 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 can be used. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a linear carbonate compound having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable.

[0174]

[0175] The above lithium salt can be used without any special limitation as long as it is a compound that can provide lithium ions used in a lithium secondary battery. Specifically, the anion of the above lithium salt is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - At least one selected from the group consisting of, and the lithium salt is LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2) 2. LiCl, LiI, or LiB(C2O4)2 can be used. The concentration of the lithium salt is preferably within the range of 0.1M to 4.0M, preferably 0.5M to 3.0M, and more preferably 1.0M to 2.0M. 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.

[0176]

[0177] 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 additives may be included in an amount of 0.1 to 10.0 wt% based on the total weight of the electrolyte.

[0178]

[0179] As described above, a lithium secondary battery including a cathode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention, 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).

[0180] 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.

[0181] 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.

[0182]

[0183] 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.

[0184]

[0185] Examples and Comparative Examples

[0186] Example 1

[0187] The transition metal precursor, lithium raw material (LiOH) and Al(OH)3 having a molar ratio of Ni:Co:Mn of 96:1:3 were mixed so that the molar ratio of transition metal (Ni+Co+Mn):Li:Al was 1:1.02:0.3, and then calcined at 870°C for 12 hours to obtain single-particle Li[Ni 0.96 Co 0.01 Mn 0.03 ] 0.977 Al 0.023 O2 was manufactured.

[0188] After that, the above-mentioned material D 50 This 200 nm Co(OH)2 and D 50 When Co(OH)2 of 800 nm was used as the final positive electrode active material standard at a ratio of 1:1, a total of 2 mol% and Al(OH)3 0.2 mol% were dry mixed and then heat-treated at 680°C for 10 hours to produce a single particle type positive electrode active material powder having a cobalt (Co) and aluminum (Al) containing coating layer formed on the surface.

[0189]

[0190] Comparative Example 1

[0191] The point that Al(OH)3 is not additionally mixed during the above firing, and D is added to the above fired product. 50 A positive electrode active material powder was manufactured in the same manner as in Example 1, except that only 2 mol% of Co(OH)2 with a diameter of 800 nm was mixed and then heat-treated.

[0192]

[0193] Comparative Example 2

[0194] A positive electrode active material powder was manufactured in the same manner as Example 1, except that Al(OH)3 was not additionally mixed during the above firing and Al(OH)3 was not additionally mixed during the above dry mixing.

[0195]

[0196] Comparative Example 3

[0197] A positive electrode active material powder was prepared in the same manner as in Example 1, except that Al(OH)3 was not additionally mixed during the above firing.

[0198]

[0199] Experimental Example 1: Characteristic Evaluation of Positive Electrode Active Materials

[0200] The results of energy dispersive X-ray spectroscopy (EDX) for (1) the inside of the nodule, (2) the nodule interface, and (3) the surface of the lithium nickel oxide particles for the positive electrode active materials of Example 1 and Comparative Examples 1 to 3 are shown in Table 1 below.

[0201] Specifically, Ar ion milling was performed on the electrode using Hitachi's IM5000 at an acceleration voltage of 6 kV, and then the concentration ratios of Ni, Co, Mn, and Al within the nodule, at the nodule interface, and on the oxide particle surface were measured using JEOL's IT8000-EDX at an acceleration voltage of 15 kV.

[0202] (1) Co concentration ratio in the nodule for the positive electrode active material [mol%] (2) Co concentration ratio at the nodule interface for the positive electrode active material [mol%] (3) Co concentration ratio at the surface of the lithium nickel-based oxide particle for the positive electrode active material [mol%] (1) Al concentration ratio in the nodule for the positive electrode active material [mol%] (2) Al concentration ratio at the nodule interface for the positive electrode active material [mol%] (3) Al concentration ratio at the surface of the lithium nickel-based oxide particle for the positive electrode active material [mol%] Example 11.020.034.51.00.90.8 Comparative Example 11.03.938.1000 Comparative Example 21.020.235.6000 Comparative Example 31.020.035.100.120.19

[0203] Experimental Example 2: Measurement of BET specific surface area of ​​positive electrode active material

[0204] For the positive electrode active materials of Example 1 and Comparative Examples 1 to 3, the nitrogen gas adsorption amount at liquid nitrogen temperature (77 K) was calculated using a specific surface area analyzer (BEL Japan, BELSORP-mino II). The results are shown in Table 2 below.

[0205] BET surface area [m 2 / g]Example 10.6Comparative Example 10.6Comparative Example 20.6Comparative Example 30.6

[0206] Experimental Example 3: High-Temperature Life Evaluation

[0207] The high-temperature life characteristics were evaluated for lithium secondary battery half cells manufactured as follows using the positive electrode active materials of Example 1 and Comparative Examples 1 to 3.

[0208]

[0209] <Manufacturing of Lithium Secondary Batteries>

[0210] The positive electrode active material, conductive agent (carbon black), and PVDF binder manufactured in Example 1 and Comparative Examples 1 to 3 were mixed in a weight ratio of 95:2:3 in N-methylpyrrolidone to manufacture a positive electrode slurry. The positive electrode slurry was applied to one surface of an aluminum current collector, dried at 130°C, and then rolled to manufacture a positive electrode.

[0211] Lithium metal was used as the negative electrode, and a separator was interposed between the positive and negative electrodes manufactured by the above-described method to manufacture an electrode assembly, which was then placed inside a battery case, and an electrolyte was injected into the case to manufacture a battery cell. The electrolyte was manufactured by dissolving 0.6 M LiPF6 in a mixed organic solvent of ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) = 1:2:1 by volume, and adding 2 wt% of vinylene carbonate (VC).

[0212]

[0213] Specifically, for each of the lithium secondary battery half cells, 50 charge-discharge cycles were performed, with one cycle being a charge-discharge cycle of 0.33C at 45°C in a voltage range of 2.5 V to 4.35 V, and then the capacity retention rate was measured using a PNE cycler. The measurement results are shown in Table 3 below.

[0214] Capacity retention rate [300 cycles, %] Example 195 Comparative Example 188 Comparative Example 290 Comparative Example 393

[0215] Through the above Table 3, it can be confirmed that the lithium secondary battery including the positive electrode active material of Example 1 has superior high-temperature life characteristics compared to the lithium secondary batteries including the positive electrode active materials of Comparative Examples 1 to 3.

Claims

1. A cathode active material comprising a lithium nickel oxide in the form of a single particle consisting of one single nodule or a quasi-single particle consisting of 30 or fewer nodules, A positive electrode active material, wherein the lithium nickel-based oxide contains cobalt (Co) and aluminum (Al), and the concentration ratio of cobalt (Co) and aluminum (Al) measured on the surface of the lithium nickel-based oxide by energy dispersive X-ray spectroscopy (EDX) satisfies the following equations 1 and 2, respectively. [Formula 1] (Co concentration ratio in the nodule for the positive electrode active material)≤(Co concentration ratio at the nodule interface for the positive electrode active material)≤(Co concentration ratio at the surface of the lithium nickel-based oxide particle for the positive electrode active material) [Formula 2] (Al concentration ratio on the surface of lithium nickel-based oxide particles for positive electrode active material)≤(Al concentration ratio at the nodule interface for positive electrode active material)<(Al concentration ratio in the nodule for positive electrode active material) 2. In claim 1, In the above formula 1, a cathode active material, wherein the Co concentration ratio in the nodule for the cathode active material is less than 5 mol%.

3. In claim 1, In the above formula 1, a cathode active material, wherein the concentration ratio of Al in the nodule to the cathode active material is 0.2 mol% or more.

4. In claim 1, The above positive electrode active material includes a coating layer formed on the surface of the lithium nickel-based oxide, A positive electrode active material, wherein the coating layer comprises at least one member selected from the group consisting of Co, Al, Mg, Ti, V, Cr, Mn, Zr, Nb, W, and B.

5. In claim 1, The above lithium nickel-based oxide is a cathode active material in which the molar ratio of Ni among all transition metals excluding lithium is 55 mol% or more.

6. The above lithium nickel-based oxide is a positive electrode active material having a composition 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 At least one selected from the group consisting of Mn and Al, and M 2 is at least one selected from the group consisting of Ti, Mg, Zr, Y, Ba, Ca, Zr, Sr, W, Ta, Nb, and Mo, and 1.0≤a≤1.5, 0.55≤b<1.0, 0 <c≤0.20, 0<d≤0.20, 0≤e≤0.10임.

7. In claim 1, A positive electrode active material, wherein the average particle size of the nodules of the positive electrode active material is 1.0 ㎛ to 10.0 ㎛.

8. In claim 1, D of the above positive electrode active material 50 A positive electrode active material having a diameter of 2.0㎛ to 10.0㎛.

9. In claim 1, The above positive electrode active material has a BET specific surface area of ​​0.2 m 2 / g to 1.5m 2 / g, positive electrode active material.

10. A step of forming a lithium nickel-based oxide by mixing a lithium nickel-based hydroxide precursor, a lithium raw material, and an aluminum-containing raw material and then calcining the mixture; and A method for producing a positive electrode active material, comprising the step of mixing two types of cobalt compounds and aluminum compounds of different sizes into the lithium nickel-based oxide and then performing heat treatment to form a coating layer.

11. In claim 10, A method for producing a positive electrode active material, wherein the above-mentioned calcination is performed at a temperature of 600°C to 1,000°C for 4 to 12 hours.

12. In claim 10, The above cobalt compound is D 50 This 50 nm to 800 nm and D 50 A method for producing a positive electrode active material, comprising mixing two types of materials having a diameter of 200 nm to 2,000 nm in a ratio of 1:3 to 3:

1.

13. In claim 10, A method for producing a positive electrode active material, wherein the above heat treatment is performed at a temperature of 600°C to 800°C for 4 to 12 hours.

14. In claim 10, A method for producing a positive electrode active material, wherein mixing of the above cobalt compound and aluminum compound is performed by a dry mixing method.

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

16. A lithium secondary battery comprising the positive electrode of claim 15.