Positive electrode active material precursor, method for manufacturing positive electrode active material precursor, positive electrode active material, and method for manufacturing positive electrode active material

Abstract

The present invention relates to a positive electrode active material precursor having high density, a method for manufacturing a positive electrode active material precursor, a positive electrode active material having high density, and a method for manufacturing a positive electrode active material. The present invention provides a positive electrode active material precursor, a method for manufacturing same, a positive electrode active material manufactured using same, and a method for manufacturing a positive electrode active material using same, wherein the positive electrode active material precursor comprises a manganese-nickel-based hydroxide containing manganese and nickel, the manganese-nickel-based hydroxide including: a porous core part (A); a first shell part (A1) formed on the core part; and a porous second shell part (A2) formed on the first shell part, first shell part (A1) having a thickness satisfying the formula 1 described in this specification, and the precursor has a tap density of 1.75g / cm3 to 2.0g / cm3 and a BET specific surface area of 18m2 / g to 25m2 / g.

Description

Positive electrode active material precursor, method for producing positive electrode active material precursor, positive electrode active material and method for producing positive electrode active material

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0175808, filed December 6, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a positive electrode active material precursor with improved density and a method for producing the same, a positive electrode active material produced using the same, and a method for producing the same.

[0005]

[0006] As technological development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which boast high energy density and voltage, long cycle life, and low self-discharge rates, are commercialized and widely used.

[0007] Lithium-transition metal composite oxides are used as cathode active materials in lithium secondary batteries. Among these, lithium-cobalt composite metal oxides, such as LiCoO2, are primarily used due to their high operating voltage and superior capacity characteristics. However, LiCoO2 suffers from poor thermal properties due to crystal structure instability following delithiation, and its high cost limits its widespread use as a power source in fields such as electric vehicles.

[0008] As materials to replace LiCoO2, lithium manganese composite metal oxides (such as LiMnO2 or LiMn2O4), lithium iron phosphate compounds (such as LiFePO4), or lithium nickel composite metal oxides (such as LiNiO2) have been developed. Among these, research and development are actively being conducted on lithium nickel composite metal oxides, which have a high reversible capacity of approximately 250 mAh / g and can easily be used to implement large-capacity batteries. However, LiNiO2 has poor thermal stability compared to LiCoO2, and there is a problem that if an internal short circuit occurs due to external pressure while charged, the positive electrode active material itself decomposes, causing the battery to rupture and catch fire.

[0009] Accordingly, as a method to improve the low thermal stability while maintaining the excellent reversible capacity of LiNiO2, a nickel-cobalt-manganese lithium composite metal oxide (hereinafter, NCM-based cathode active material) was developed in which some of the Ni was replaced with Mn and Co or Al.

[0010] However, due to the recent rise in the price of cobalt (Co), development of lithium-rich NCM cathode active materials that can meet high capacity while containing or not containing relatively low cobalt (Co) content is underway.

[0011] Meanwhile, cobalt-free, Li- and Mn-rich cathode active materials require a large amount of lithium for sintering, unlike typical NCM cathode active materials. Therefore, a porous structure through internal pore and primary particle shape control is required for smooth diffusion. However, the porous structure has the problem of lowering the strength of the cathode active material particles, causing the particles to break during electrode rolling. Incidentally, the broken particles generate gases through side reactions with the electrolyte during the charge and discharge process of the battery, which lowers the stability and performance of the battery.

[0012] Therefore, there is a need to develop a cathode active material precursor and cathode active material with improved internal density in a cobalt-free, Mn-rich precursor.

[0013]

[0014] The present invention is intended to solve the above problems and to provide a positive electrode active material precursor capable of implementing a high-density positive electrode active material.

[0015] In addition, the present invention provides a method for producing the positive electrode active material precursor.

[0016] In addition, the present invention provides a positive electrode active material manufactured using the positive electrode active material precursor and a method for manufacturing the same.

[0017]

[0018] In order to solve the above problem, the present invention provides a positive electrode active material precursor, a method for producing the positive electrode active material precursor, a positive electrode active material, and a method for producing the positive electrode active material.

[0019]

[0020] (1) The present invention comprises a manganese-nickel hydroxide containing manganese and nickel, wherein the manganese-nickel hydroxide comprises a porous core portion (A); a first shell portion (A1) formed on the core portion; and a porous second shell portion (A2) formed on the first shell portion, wherein the thickness of the first shell portion (A1) satisfies the following equation 1, and the tap density is 1.75 g / cm. 3 2.0g / cm 3 , and the BET surface area is 18m 2 / g to 25m 2 / g provides a positive electrode active material precursor.

[0021] [Formula 1]

[0022] 0.15×(average particle size of manganese nickel hydroxide (D 50 )) < thickness of the first shell (A1) < 0.30×(average particle size of manganese nickel hydroxide (D 50 )).

[0023] (2) The present invention provides a positive electrode active material precursor in the above (1), wherein the diameter of the core portion (A) satisfies the following equation 2.

[0024] [Formula 2]

[0025] 0 < diameter of core (A) < (average particle diameter of manganese nickel hydroxide (D) 50 )) / 3.

[0026] (3) The present invention provides a positive electrode active material precursor in (1) or (2) above, wherein the thickness of the second shell portion (A2) satisfies the following equation 3.

[0027] [Formula 3]

[0028] 0.04×(average particle size of manganese nickel hydroxide (D 50 )) ≤ thickness of the second shell (A2) ≤ 0.15×(average particle diameter of manganese nickel hydroxide (D 50 )).

[0029] (4) The present invention provides a positive electrode active material precursor in any one of the above (1) to (3), wherein the manganese nickel-based hydroxide contains manganese in an amount of 50 mol% or more among the total transition metals.

[0030] (5) The present invention provides a positive electrode active material precursor according to any one of the above (1) to (4), wherein the manganese nickel-based hydroxide has a composition represented by the following chemical formula 1.

[0031] [Chemical Formula 1]

[0032] [Mn a1 Ni b1 M c1 ](OH)2

[0033] In the above chemical formula 1,

[0034] M is at least one selected from Zr, Al, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, W, Na, and Pt,

[0035] 0.5≤a1<1.0, 0 <b1≤0.5, 0≤c1≤0.1, a1+b1+c1=1이다.

[0036] (6) In any one of the above (1) to (5), the manganese nickel hydroxide has an average particle diameter (D 50 ) provides a positive electrode active material precursor having a diameter of 1 μm to 15 μm.

[0037] (7) The present invention provides a positive electrode active material precursor in any one of the above (1) to (6), wherein the diameter of the core portion (A) is 0.33 µm or more and less than 5 µm, the thickness of the first shell portion (A1) is 0.3 µm or more and 4.5 µm or less, and the thickness of the second shell portion (A2) is 0.05 µm or more and 0.75 µm or less.

[0038] (8) The present invention comprises the steps of (S1) adding a solvent and a basic solution to a reactor to adjust the pH to 12.0 to 13.0, and then purging an inert gas to create a non-oxidizing atmosphere; (S2) continuously adding a transition metal-containing solution containing manganese and nickel and a basic solution to the reactor, and performing a coprecipitation reaction under a pH of 12.0 to 13.0 to form a porous core portion (A); (S3) continuously adding a transition metal-containing solution containing manganese and nickel and a basic solution to the reactor that has gone through the step (S2), and performing a coprecipitation reaction by lowering the pH by 0.25 to 0.5 every 20 to 60 minutes under a pH of 10.0 to 11.0 and then restoring it, and forming a first shell portion (A1) on the porous core portion (A); And (S4) a step of continuously introducing a transition metal-containing solution containing manganese and nickel and a basic solution into a reactor that has gone through step (S3), and performing a co-precipitation reaction at a pH of 10.0 to 11.0 to form a porous second shell part (A2) on the first shell part (A1) to produce a manganese-nickel hydroxide containing manganese and nickel; wherein steps (S2) to (S4) are performed under an oxidizing atmosphere, and the co-precipitation reaction of step (S3) is performed for 5 to 25 hours.

[0039] (9) The present invention provides a method for producing a positive electrode active material precursor, wherein, in the above (8), the co-precipitation reaction of the above (S2) step is performed for 0.1 to 2.0 hours.

[0040] (10) The present invention provides a method for producing a positive electrode active material precursor, wherein the co-precipitation reaction in step (S4) is performed for 35 to 55 hours in the above (8) or (9).

[0041] (11) The present invention provides a method for producing a positive electrode active material precursor, wherein the oxidizing atmosphere is formed by introducing air and an inert gas into a reactor in any one of the above (8) to (10).

[0042] (12) The present invention provides a method for manufacturing a positive electrode active material precursor, wherein the atmosphere and the inert gas are introduced in a volume ratio of 0.5:99.5 to 15:85 in any one of the above (8) to (11).

[0043] (13) The present invention includes a lithium-excess manganese-nickel oxide containing manganese and nickel, wherein the lithium-excess manganese-nickel oxide simultaneously includes a Li2MnO3 phase and a LiMO2 (wherein M includes at least one selected from Ni and Mn) phase, wherein the lithium-excess manganese-nickel oxide includes a porous core portion (B); a first shell portion (B1) formed on the core portion; and a porous second shell portion (B2) formed on the first shell portion, wherein the thickness of the first shell portion (B1) satisfies the following equation 4, and the pellet density is 2.5 g / cm 3 3.00g / cm 3 and the BET surface area is 0.20 m 2 / g to 1.0m 2 / g provides a positive electrode active material.

[0044] [Formula 4]

[0045] 0.15×(average particle size of lithium-excess manganese nickel oxide (D 50 )) < thickness of the first shell (B1) < 0.32×(average particle size of lithium-excess manganese nickel oxide (D 50 )).

[0046] (14) The present invention provides a positive electrode active material in (13) above, wherein the lithium-excess manganese nickel oxide contains manganese in an amount of 50 mol% or more among all transition metals excluding lithium.

[0047] (15) The present invention provides a positive electrode active material in (13) or (14), wherein the lithium-excess manganese nickel oxide has a composition represented by the following chemical formula 2.

[0048] [Chemical Formula 2]

[0049] xLi2Mn (1-p) M 1 p O3·(1-x)LiNi q Mn r M 2 s O2

[0050] In the above chemical formula 2,

[0051] M 1 and M 2 are each independently at least one selected from Zr, Al, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, W, Na and Pt,

[0052] 0 <x<1.0, 0≤p≤0.1, 0<q≤0.5, 0.5≤r<1.0, 0≤s≤0.1, q+r+s=1이다.

[0053] (16) The present invention provides a method for manufacturing a positive electrode active material, which comprises the step of mixing a positive electrode active material precursor according to any one of (1) to (7) and a lithium raw material, and then calcining the mixture.

[0054] (17) The present invention provides a method for producing a positive electrode active material, wherein, in the above (16), the positive electrode active material precursor and the lithium raw material are mixed so that the molar ratio of the total metal elements present in the positive electrode active material precursor and the lithium present in the lithium raw material is 1:1.2 to 1:1.6.

[0055] (18) The present invention provides a method for producing a positive electrode active material, wherein the calcination is performed at 850°C to 950°C in the above (16) or (17).

[0056]

[0057] The positive electrode active material precursor according to the present invention can provide a positive electrode active material having a low BET specific surface area and a high tap density by including an internal densification region having a specific thickness.

[0058] According to the method for producing a positive electrode active material precursor of the present invention, the positive electrode active material precursor can be easily produced.

[0059] The cathode active material according to the present invention includes an internal densified region having a specific thickness, and thus has a low BET specific surface area and a high pellet density, enabling the implementation of a battery with excellent energy density.

[0060] According to the method for manufacturing a positive electrode active material of the present invention, the positive electrode active material can be easily manufactured.

[0061]

[0062] Figure 1 is a cross-sectional SEM image of the positive electrode active material precursor of Example 1.

[0063] Figure 2 is a cross-sectional SEM image of the positive electrode active material of Example 1.

[0064] Figure 3 is a cross-sectional SEM image of the positive electrode active material precursor of Example 2.

[0065] Figure 4 is a cross-sectional SEM image of the positive electrode active material of Example 2.

[0066] Figure 5 is a cross-sectional SEM image of the positive electrode active material precursor of Comparative Example 1.

[0067] Figure 6 is a cross-sectional SEM image of the positive electrode active material of Comparative Example 1.

[0068] Figure 7 is a cross-sectional SEM image of the positive electrode active material precursor of Comparative Example 2.

[0069] Figure 8 is a cross-sectional SEM image of the positive electrode active material of Comparative Example 2.

[0070]

[0071] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0072] The terms or words used in the description and claims of the present invention should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0073] In this specification, it should be understood that terms such as “include,” “have,” or “have” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0074] In this specification, the average particle diameter (D 50 ) can be defined as the particle size corresponding to 50% of the volume accumulation in the particle size distribution curve. The average particle size (D 50 ) can be measured, for example, using a laser diffraction method, and more specifically, after dispersing a lithium composite transition metal oxide in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac Mt 3000) and irradiated with an ultrasonic wave of about 28 kHz at an output of 60 W, and then the average particle diameter (D) corresponding to 50% of the particle size distribution in the measuring device is measured. 50 ) can be produced.

[0075] In this specification, the tap density is a value calculated by placing 50 g of a positive electrode active material precursor sample in a cylinder, tapping the cylinder containing the sample 3000 times using Tap Denser KYT-5000 (SEISHIN), reading the scale value to measure the volume, and then calculating the tap density.

[0076] In this specification, the BET specific surface area is a value measured by nitrogen adsorption method after pretreatment of 3.00 g of a sample at 200°C under vacuum conditions using a surface area analyzer TriStar 2 plus (Micromeritics).

[0077] In this specification, the pellet density is a value calculated by Equation 5 below when a force equivalent to 2,000 kgf is applied to form a pellet using an automatic pellet press. Specifically, the pellet density is a value obtained according to (1) to (3) below.

[0078] (1) Using a universal testing machine (UTM: Universal Testing Machine, Instron, Model 5966), adjust the zero point for thickness using a cylindrical mold for a circular pellet holder.

[0079] (2) Place the positive electrode active material in the above circular pellet holder, apply force until a force equivalent to 2,000 kgf is reached, and measure the thickness of the formed pellet.

[0080] (3) Calculate the pellet volume using the following equation 5, and calculate the pellet density using the following equation 6.

[0081] [Formula 5]

[0082] Pellet volume (cm) 3 ) = π(radius of the circular pellet holder) 2 × Pellet thickness

[0083] [Formula 6]

[0084] Pellet density (g / cm) 3 ) = Positive active material weight (g) / Pellet volume (cm 3 )]]

[0085]

[0086] Cathode active material precursor

[0087] The present invention provides a positive electrode active material precursor capable of providing a positive electrode active material having excellent density by including a densified region therein and exhibiting a BET specific surface area and tap density in a specific range.

[0088] The cathode active material according to the present invention comprises a manganese-nickel hydroxide containing manganese and nickel, wherein the manganese-nickel hydroxide comprises a porous core portion (A); a first shell portion (A1) formed on the core portion; and a porous second shell portion (A2) formed on the first shell portion, wherein the thickness of the first shell portion (A1) satisfies the following equation 1, and the cathode active material has a tap density of 1.75 g / cm. 3 2.0g / cm 3 , and the BET surface area is 18m 2 / g to 25m 2 / g is.

[0089]

[0090] Unlike typical NCM-based cathode active materials, cobalt-free, Li- and Mn-rich cathode active materials require a large amount of lithium for sintering. Therefore, a porous structure is required, with controlled internal pores and primary particle shape to facilitate lithium diffusion. However, this porous structure reduces the strength of the cathode active material particles, leading to particle breakage during electrode rolling. This, in turn, degrades battery performance.

[0091] However, the positive electrode active material precursor according to the present invention includes a first shell portion (A1) which is a dense region inside with a specific thickness and has a tap density of 1.75 g / cm 3 2.0g / cm 3 And the BET surface area is 18m 2 / g to 25m 2 / g is satisfied, and the density of the positive electrode active material manufactured using it can be improved. The first shell portion (A1) is a region in which the pores (air gaps) are relatively significantly smaller than those of the core portion and the second shell portion.

[0092] Meanwhile, the tap density of the positive electrode active material precursor is 1.75 g / cm 3 If it is less than 2.0 g / cm, it is not possible to implement a cathode active material with high energy density. 3 In case of excess, the internal density of the precursor is too high, which is disadvantageous when firing with lithium, making firing difficult, or even if firing is successful, making it difficult to develop capacity.

[0093] And, the BET specific surface area of ​​the positive electrode active material precursor is 18 m 2 If it is less than / g, the plasticity with lithium is unfavorable, and 25m 2 / g exceeds, there is a problem that a high energy density cathode active material cannot be implemented.

[0094]

[0095] According to the present invention, the thickness of the first shell portion (A1) satisfies the following equation 1. In this case, even if high pressure is applied in the process of manufacturing an electrode using a positive electrode active material manufactured from a positive electrode active material precursor according to the present invention, particle breakage of the positive electrode active material does not occur, thereby ensuring a high energy density.

[0096] [Formula 1]

[0097] 0.15×(average particle size of manganese nickel hydroxide (D 50 )) < thickness of the first shell (A1) < 0.30×(average particle size of manganese nickel hydroxide (D 50 ))

[0098] Meanwhile, if the thickness of the first shell portion (A1) is less than 0.15 times the average particle diameter of the manganese nickel hydroxide, there is a problem of particle breakage occurring in the process of manufacturing an electrode using the positive electrode active material manufactured therefrom, and if it is 0.30 times or more, lithium ion movement of the positive electrode active material manufactured therefrom is not easy, so the capacity of the battery is rather reduced, resulting in a problem of low energy density.

[0099]

[0100] According to the present invention, the diameter of the core portion (A) may satisfy the following equation 2. This is a condition for a stable seed formation reaction during the manufacture of a positive electrode active material precursor, and the reproducibility is high during continuous production, and the subsequent particle growth process can be easily performed.

[0101] [Formula 2]

[0102] 0 < diameter of core (A) < (average particle diameter of manganese nickel hydroxide (D) 50 )) / 3

[0103]

[0104] According to the present invention, the thickness of the second shell portion (A2) may satisfy the following equation 3. In this case, lithium ion movement is facilitated on the surface of the positive electrode active material manufactured from the positive electrode active material precursor according to the present invention, so that the performance of the battery can be secured.

[0105] [Formula 3]

[0106] 0.04×(average particle size of manganese nickel hydroxide (D 50 )) ≤ thickness of the second shell (A2) ≤ 0.15×(average particle diameter of manganese nickel hydroxide (D 50 ))

[0107]

[0108] The core portion (A) and the second shell portion (A2) may each independently have a porosity of greater than 0% and less than or equal to 30%. In this case, the movement of lithium ions is facilitated, so that the performance of a battery including a positive electrode active material manufactured from the positive electrode active material precursor according to the present invention may be excellent.

[0109]

[0110] According to the present invention, the manganese-nickel hydroxide may contain manganese in an amount of at least 50 mol% of the total transition metal. In this case, the capacity of a battery comprising a positive electrode active material prepared from the positive electrode active material precursor according to the present invention may be high.

[0111] According to the present invention, the manganese nickel-based hydroxide may have a composition represented by the following chemical formula 1. In this case, the capacity of a battery including a positive electrode active material manufactured from the positive electrode active material precursor according to the present invention may be excellent.

[0112] [Chemical Formula 1]

[0113] [Mn a1 Ni b1 M c1 ](OH)2

[0114] In the above chemical formula 1,

[0115] M is at least one selected from Zr, Al, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, W, Na, and Pt,

[0116] 0.5≤a1<1.0, 0 <b1≤0.5, 0≤c1≤0.1, a1+b1+c1=1이다.

[0117] The above M is a doping element, and although it is not necessarily included, when included in an appropriate amount, the particle shape of the positive electrode active material can be improved and the stability of the crystal structure can be enhanced.

[0118] Meanwhile, the manganese nickel hydroxide may not contain expensive cobalt, and may improve the performance of a lithium secondary battery without containing cobalt.

[0119]

[0120] According to the present invention, the manganese nickel hydroxide has an average particle diameter (D 50 ) may be 1㎛ to 15㎛. The average particle diameter (D) of the manganese nickel hydroxide 50) may be specifically 1.0㎛ or more, 1.5㎛ or more, 2.0㎛ or more, 2.5㎛ or more, or 3.0㎛ or more, and may be 10㎛ or less, 10.5㎛ or less, 11㎛ or less, 11.5㎛ or less, 12㎛ or less, 12.5㎛ or less, 13㎛ or less, 13.5㎛ or less, 14㎛ or less, 14.5㎛ or less, or 15㎛ or less.

[0121]

[0122] According to the present invention, the diameter of the core portion (A) may be 0.33 µm or more and less than 5 µm, the thickness of the first shell portion (A1) may be 0.3 µm or more and 4.5 µm or less, and the thickness of the second shell portion (A2) may be 0.05 µm or more and 0.75 µm or less.

[0123] The diameter of the core portion (A) may be specifically 0.33 ㎛, 1.0 ㎛ or more, 4.0 ㎛ or less, or less than 5 ㎛ to minimize the influence on the design of the first shell portion (A1) and the second shell portion (A2).

[0124] The thickness of the above first shell portion (A1) may be specifically 0.3 µm, 0.90 µm or more, 3.6 µm or less, or 4.5 µm or less. In this case, particle breakage is prevented even during the electrode process at high density, thereby ultimately securing a high energy density.

[0125] The thickness of the second shell portion (A2) may be specifically 0.05 µm, 0.10 µm or more, 0.40 µm or less, or 0.75 µm or less. In this case, lithium diffusion may be facilitated.

[0126]

[0127] According to the present invention, the positive electrode active material precursor may be in the form of secondary particles formed by agglomeration of primary particles. Specifically, as described below, the precursor may be manufactured in an oxidizing atmosphere, and may be in the form of secondary particles formed by agglomeration of thin, short, uniform, needle-shaped primary particles. In this case, the precursor readily reacts with an excess of lithium, thereby facilitating the manufacture of a Li- and Mn-rich positive electrode active material.

[0128]

[0129] Method for manufacturing a cathode active material precursor

[0130] The present invention provides a method for manufacturing a positive electrode active material precursor according to the present invention described above.

[0131] The method for manufacturing a positive electrode active material precursor according to the present invention comprises the steps of: (S1) adding a solvent and a basic solution to a reactor to adjust the pH to 12.0 to 13.0, and then purging an inert gas to create a non-oxidizing atmosphere; (S2) continuously adding a transition metal-containing solution containing manganese and nickel and a basic solution to the reactor, and performing a coprecipitation reaction at a pH of 12.0 to 13.0 to form a porous core portion (A); (S3) continuously adding a transition metal-containing solution containing manganese and nickel and a basic solution to the reactor that has gone through the step (S2), and performing a coprecipitation reaction by lowering the pH by 0.25 to 0.5 every 20 to 60 minutes at a pH of 10.0 to 11.0 and then restoring it, and forming a first shell portion (A1) on the porous core portion (A); And (S4) a step of continuously introducing a transition metal-containing solution containing manganese and nickel and a basic solution into a reactor that has gone through step (S3), and performing a co-precipitation reaction at a pH of 10.0 to 11.0 to form a porous second shell part (A2) on the first shell part (A1), thereby producing a manganese-nickel hydroxide containing manganese and nickel; wherein steps (S2) to (S4) are performed under an oxidizing atmosphere, and the co-precipitation reaction of step (S3) is performed for 5 to 25 hours.

[0132]

[0133] Hereinafter, the method for manufacturing a positive electrode active material precursor according to the present invention will be described in detail step by step.

[0134]

[0135] (S1) Step

[0136] The above step (S1) is a step for adjusting the inside of the reactor to a specific pH condition and a non-oxidizing (inert) atmosphere before the co-precipitation reaction. This can be performed by adding a solvent and a basic solution to the reactor to adjust the pH to 12.0 to 13.0, and then purging with an inert gas.

[0137] The solvent may be a polar solvent commonly used in the art, for example, water (distilled water, deionized water), alcohol, or a mixture thereof.

[0138] The above inert gas may be used without particular limitation as long as it is an inert gas commonly used in the art, but may be, for example, at least one selected from nitrogen, argon, helium, and neon, and specifically, may be nitrogen.

[0139] The above basic solution is a precipitant and serves to control the pH within the reactor, and may be a solution containing 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 above basic solution may be an aqueous basic solution, and in this case, a mixture of water (distilled water, deionized water) or an organic solvent (e.g., alcohol, etc.) that can be evenly mixed with water may be used as the solvent.

[0140]

[0141] When the pH of the above step (S1) is 12.0 to 13.0, when a solution containing a transition metal including manganese and nickel is introduced in a subsequent step, seeds can be appropriately generated without clumping. On the other hand, when the pH of the step (S1) exceeds 13.0, there is a problem that seeds are excessively generated, limiting the particle growth rate, and when it is less than 12.0, there is a problem that the growth rate is too fast due to clumping between particles.

[0142]

[0143] (S2) step to (S4) step

[0144] The above steps (S2) to (S4) are steps for producing manganese nickel hydroxide by co-precipitation reaction of a transition metal. The inside of the reactor is re-formed into an active atmosphere (oxidizing atmosphere), a solution containing a transition metal and a basic solution are introduced, and a co-precipitation reaction is performed at pH 12.0 to 13.0, and then a co-precipitation reaction is performed at pH 10.0 to 11.0.

[0145] Specifically, (S2) a solution containing a transition metal including manganese and nickel and a basic solution are continuously introduced into the reactor, and a coprecipitation reaction is performed under a pH of 12.0 to 13.0 to form a porous core portion (A), (S3) a solution containing a transition metal including manganese and nickel and a basic solution are continuously introduced into the reactor that has gone through step (S2), and the process of lowering the pH by 0.25 to 0.5 every 20 to 60 minutes under a pH of 10.0 to 11.0 and then restoring it is repeated to cause a coprecipitation reaction to form a first shell portion (A1) on the porous core portion (A), and (S4) a solution containing a transition metal including manganese and nickel and a basic solution are continuously introduced into the reactor that has gone through step (S3), and a coprecipitation reaction is performed under a pH of 10.0 to 11.0 to form a porous second shell portion (A2) on the first shell portion (A1), thereby forming manganese and nickel. It is to manufacture a manganese nickel hydroxide containing:

[0146] As in the present invention, when a co-precipitation reaction is performed under an oxidizing atmosphere, thin and uniform primary particles can be formed, and the BET specific surface area and density of the positive electrode active material precursor thus manufactured can be the same as those of the positive electrode active material precursor according to the present invention described above.

[0147] According to the present invention, the oxidizing atmosphere may be formed by introducing air and an inert gas into the reactor.

[0148] Specifically, the oxidizing atmosphere can be formed by introducing air and an inert gas into the reactor at a volume ratio of 0.5:99.5 to 15:85. Here, the inert gas can be as described above, and specifically, can be nitrogen.

[0149]

[0150] According to the present invention, the formation of the porous core portion (A) can be achieved at a pH of 12.0 to 13.0, and the formation of the first shell portion (A1) and the second shell portion (A2) can be achieved at a pH of 10.0 to 11.0. This is because seeds of the positive electrode active material precursor are formed at a pH of 12.0 to 13.0, and positive electrode active material precursor particles grow at a pH of 10.0 to 11.0.

[0151] Meanwhile, the growth of the positive electrode active material precursor particles may be performed under pH 10.0 to 11.0 for stable simultaneous coprecipitation, and when the pH is lower than 10.0, the transition metals present in the transition metal-containing solution do not coprecipitate simultaneously, which may result in a difference in the composition of the transition metal-containing solution and the synthesized precursor.

[0152] In addition, the formation of the first shell portion (A1) may be performed by changing the pH by 0.25 to 0.5 within the pH range of 10.0 to 11.0 at intervals of 20 to 60 minutes, rather than continuously maintaining the pH constant. In this case, the coprecipitation reaction that increases the density of the particles occurs more easily than the coprecipitation reaction that attempts to grow outward from the center of the particles, so that a first shell portion (A1) with almost no pores may be formed. In other words, a first shell portion (A1) having relatively significantly fewer pores (air voids) compared to the core portion and the second shell portion may be formed.

[0153] Finally, the formation of the second shell portion (A2) may be performed at a specific pH within the range of pH 10.0 to 11.0. That is, it may be performed under a constant pH. When the coprecipitation reaction is performed under an oxidizing atmosphere, thin and uniform primary particles are formed, and when the pH is constant, the coprecipitation reaction occurs well in the growth direction, resulting in the formation of pores.

[0154]

[0155] According to the present invention, the co-precipitation reaction of the step (S2) may be performed for 0.1 to 2.0 hours. Specifically, the co-precipitation reaction time of the step (S2) may be 0.1 hour or more, 0.2 hours or more, 0.3 hours or more, 0.4 hours or more, or 0.5 hours, and may be 1.0 hour or less, 1.1 hour or less, 1.2 hours or less, 1.3 hours or less, 1.4 hours or less, 1.5 hours or less, 1.6 hours or less, 1.7 hours or less, 1.8 hours or less, 1.9 hours or less, or 2.0 hours or less. In this case, the amount and size of the seeds can be stably synthesized.

[0156] According to the present invention, the co-precipitation reaction of the step (S3) is performed for 5 to 25 hours. Specifically, the co-precipitation reaction time of the step (S3) may be 5 hours or more, 6 hours or more, 7 hours or more, 8 hours or more, 9 hours or more, or 10 hours or less, 20 hours or less, 21 hours or less, 22 hours or less, 23 hours or less, 24 hours or less, or 25 hours or less. In this case, the density can be increased while minimizing the deterioration of electrochemical performance. On the other hand, when the co-precipitation reaction time of the step (S3) is less than 5 hours, the thickness of the first shell part (A1) is thin, which causes a problem of particle breakage in the process of manufacturing an electrode using the positive electrode active material manufactured therefrom. In addition, when it exceeds 25 hours, the thickness of the first shell part (A1) is thick, which makes it difficult for lithium ions to move in the positive electrode active material manufactured therefrom, thereby lowering the capacity of the battery and causing a problem of low energy density.

[0157]

[0158] According to the present invention, the co-precipitation reaction of step (S4) may be performed for 35 to 55 hours. Specifically, the co-precipitation reaction time of step (S4) may be 35 hours or more, 36 hours or more, 37 hours or more, 38 hours or more, 39 hours or more, or 40 hours or less, 50 hours or less, 51 hours or less, 52 hours or less, 53 hours or less, 54 hours or less, or 55 hours or less. In this case, formation of thin, needle-shaped primary particles advantageous for sintering is possible.

[0159]

[0160] Specifically, the coprecipitation reaction may be performed by starting to introduce a transition metal-containing solution and a basic solution into a reactor, adjusting the amount of the basic solution introduced so that the pH in the reactor becomes 10.0 to 11.0 from 12.0 to 13.0 within 0.5 to 1.0 hours, and then proceeding with the reaction for 10 to 20 hours while changing the pH by 0.5 to 1.0 within the pH range of 10.0 to 11.0 at intervals of 20 to 60 minutes, and then proceeding with the reaction for 40 to 50 hours while maintaining the pH at 10.0 to 11.0.

[0161]

[0162] In addition, the above-mentioned coprecipitation reaction can be carried out while stirring at a temperature of 40°C to 60°C, and the stirring speed is not particularly limited, but may be stirred at 100 rpm to 1,000 rpm in terms of improving the reaction speed.

[0163]

[0164] The above transition metal-containing solution may be prepared by adding and mixing a transition metal raw material to a solvent, specifically, water (distilled water, deionized water) or a mixed solvent of an organic solvent (e.g., alcohol, etc.) that can be uniformly mixed with water, or may be prepared by mixing an aqueous solution of a transition metal raw material.

[0165] The above transition metal-containing solution may contain manganese in an amount of 50 mol% or more among the total transition metals in the solution. The above transition metal-containing solution may not contain cobalt.

[0166] The above transition metal raw material may be a sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide or oxyhydroxide containing a transition metal.

[0167] As a specific example, the nickel source material may be, for example, a nickel-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, and more specific examples may be, but are not limited to, Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, NiSO4·6H2O, a fatty acid nickel salt, a nickel halide or a combination thereof.

[0168] And, the manganese raw material may be, for example, a manganese-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, and more specific examples include, but are not limited to, manganese oxides such as Mn2O3, MnO2, Mn3O4; manganese salts such as MnCO3, Mn(NO3)2, MnSO4, manganese acetate, manganese dicarboxylic acid salt, manganese citrate, manganese fatty acid salt; manganese oxyhydroxide, manganese chloride or a combination thereof.

[0169] Meanwhile, the transition metal-containing solution may further include at least one selected from among Zr, Al, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, W, Na, and Pt, and in this case, the transition metal-containing solution may further include a raw material containing the Zr, Al, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, W, Na, or Pt, and the raw material may be an acetate, a nitrate, a sulfate, a halide, a sulfide, a hydroxide, an oxide, or an oxyhydroxide containing each of the above metals.

[0170]

[0171] In addition, the method for manufacturing a positive electrode active material precursor according to the present invention may further perform at least one step selected from filtration, washing, and drying after step (S2). In addition, the filtration, washing, and drying may be performed using methods commonly known in the art.

[0172]

[0173] positive electrode active material

[0174] The present invention provides a high-density positive electrode active material manufactured using the positive electrode active material according to the present invention described above.

[0175] The cathode active material according to the present invention includes a lithium-excess manganese-nickel oxide containing manganese and nickel, and the lithium-excess manganese-nickel oxide simultaneously includes a Li2MnO3 phase and a LiMO2 (wherein M includes at least one selected from Ni and Mn) phase, and the lithium-excess manganese-nickel oxide includes a porous core portion (B); a first shell portion (B1) formed on the core portion; and a porous second shell portion (B2) formed on the first shell portion, and the thickness of the first shell portion (B1) satisfies the following equation 4. In addition, the cathode active material according to the present invention has a pellet density of 2.5 g / cm. 3 3.00g / cm 3 and the BET surface area is 0.20 m 2 / g to 1.0m 2 / g is.

[0176] [Formula 4]

[0177] 0.15×(average particle size of lithium-excess manganese nickel oxide (D 50 )) < thickness of the first shell (B1) < 0.32×(average particle size of lithium-excess manganese nickel oxide (D 50 ))

[0178]

[0179] Specifically, the positive electrode active material according to the present invention is manufactured from a positive electrode active material precursor that includes a densified region (first shell portion (B1)) with a specific thickness inside and has a BET specific surface area and a tap density that satisfy a specific range, so that the pellet density is high and the energy density is excellent. The positive electrode active material according to the present invention has a high pellet density, so that an electrode process is possible without breaking even at a high rolling rate, and thus the energy density is high. Meanwhile, the positive electrode active material according to the present invention has a BET specific surface area within the above range because the internal specific surface area is reduced as the density increases.

[0180]

[0181] According to the present invention, the thickness of the first shell portion (B1) satisfies the following equation 4. In this case, even if high pressure is applied in the process of manufacturing an electrode using the positive electrode active material according to the present invention, particle breakage of the positive electrode active material does not occur, thereby ensuring a high energy density.

[0182] [Formula 4]

[0183] 0.15×(average particle size of lithium-excess manganese nickel oxide (D 50 )) < thickness of the first shell (B1) < 0.32×(average particle size of lithium-excess manganese nickel oxide (D 50 ))

[0184] Meanwhile, if the thickness of the first shell portion (B1) is less than 0.15 times the average particle size of the lithium-excess manganese nickel oxide, there is a problem of particle breakage occurring in the process of manufacturing an electrode using the positive electrode active material, and if it is 0.32 times or more, lithium ion movement of the positive electrode active material is not easy, so the capacity of the battery is reduced and there is a problem of low energy density.

[0185]

[0186] According to the present invention, the lithium-excess manganese-nickel oxide may contain manganese in an amount of 50 mol% or more among all transition metals excluding lithium. In this case, it may be easy to secure a high capacity of the positive electrode active material.

[0187] According to the present invention, the lithium-excess manganese nickel oxide may have a composition represented by the following chemical formula 2. In this case, the capacity of a battery including a positive electrode active material may be excellent.

[0188] [Chemical Formula 2]

[0189] xLi2Mn (1-p) M 1 p O3·(1-x)LiNi q Mn r M 2 s O2

[0190] In the above chemical formula 2,

[0191] M 1 and M 2 are each independently at least one selected from Zr, Al, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, W, Na and Pt,

[0192] 0 <x<1.0, 0≤p≤0.1, 0<q≤0.5, 0.5≤r<1.0, 0≤s≤0.1, q+r+s=1이다.

[0193] Above M 1 and M 2 is a doping element, and although it is not necessarily included, when included in an appropriate amount, the particle shape of the lithium-excess manganese nickel oxide can be improved and the stability of the crystal structure can be enhanced.

[0194] Meanwhile, the lithium-excess manganese nickel oxide may not contain expensive cobalt, and may improve the performance of a lithium secondary battery without containing cobalt.

[0195]

[0196] According to the present invention, the lithium-excess manganese nickel oxide has an average particle diameter (D 50 ) may be 1.0㎛ to 15㎛. The average particle diameter (D) of the lithium-excess manganese nickel oxide 50 ) may be specifically 1.0㎛ or more, 1.5㎛ or more, 2.0㎛ or more, 2.5㎛ or more, or 3.0㎛ or more, and may be 12㎛ or less, 12.5㎛ or less, 13㎛ or less, 13.5㎛ or less, 14㎛ or less, 14.5㎛ or less, or 15㎛ or less.

[0197]

[0198] According to the present invention, the diameter of the core portion (B) may be 0.33 µm or more and less than 5 µm, the thickness of the first shell portion (B1) may be 0.3 µm or more and 4.5 µm or less, and the thickness of the second shell portion (B2) may be 0.05 µm or more and 0.75 µm or less.

[0199] The diameter of the core portion (B) may be specifically 0.33 ㎛, 1.0 ㎛ or more, 4.0 ㎛ or less, or less than 5 ㎛ to minimize the influence on the design of the first shell portion (A1) and the second shell portion (A2).

[0200] The thickness of the first shell portion (B1) may be specifically 0.3 µm, 0.90 µm or more, 3.6 µm or less, or 4.5 µm or less. In this case, particle breakage is prevented even during the electrode process at high density, thereby ultimately securing a high energy density.

[0201] The thickness of the second shell portion (B2) may be specifically 0.05 µm, 0.10 µm or more, 0.40 µm or less, or 0.75 µm or less. In this case, lithium diffusion may be facilitated.

[0202]

[0203] Method for manufacturing positive electrode active material

[0204] The present invention provides a method for producing a positive electrode active material, which can produce the positive electrode active material according to the present invention described above.

[0205] The method for manufacturing a positive electrode active material according to the present invention includes a step of mixing the positive electrode active material precursor according to the present invention described above with a lithium raw material, and then calcining the mixture.

[0206]

[0207] The above lithium raw material may include lithium-containing carbonates (e.g., lithium carbonate, etc.), hydrates (e.g., lithium hydroxide hydrate (LiOH·H2O)), hydroxides (e.g., lithium hydroxide, etc.), nitrates (e.g., lithium nitrate (LiNO3)), chlorides (e.g., lithium chloride (LiCl)), etc., and one of these may be used alone or a mixture of two or more may be used.

[0208]

[0209] The mixing of the above positive electrode active material precursor and the lithium raw material can be achieved by solid-state mixing such as jet milling, and the mixing ratio of the positive electrode active material precursor and the lithium raw material can be determined within a range that satisfies the mole fraction of each component in the positive electrode active material to be finally manufactured.

[0210] According to the present invention, the positive electrode active material precursor and the lithium raw material may be mixed so that the molar ratio of the total metal elements present in the positive electrode active material precursor and the lithium present in the lithium raw material is 1:1.2 to 1:1.6. In this case, a two-phase Li and Mn-rich positive electrode active material without impurity phases can be produced.

[0211]

[0212] In addition, although not essential, during the mixing, raw materials for doping a portion of the transition metal and / or oxygen of the positive electrode active material may be additionally included in addition to the positive electrode active material precursor and the lithium raw material. For example, the M-containing raw material described above or the X-containing raw material described below may be additionally mixed during the mixing. At this time, the X-containing raw material may be, for example, Na3PO4, K3PO4, Mg3(PO4)2, AlF3, NH4F, LiF, etc., but is not limited thereto. When a portion of the oxygen is replaced by the X element as described above, the effect of suppressing oxygen desorption and reaction with the electrolyte during charge and discharge of the secondary battery can be obtained.

[0213]

[0214] According to the present invention, the sintering can be performed at 800°C to 1,000°C, specifically 850°C to 950°C. In this case, all excess lithium ions can participate in the reaction, and a two-phase, highly crystalline, Li- and Mn-rich cathode active material without impurity phases can be produced.

[0215]

[0216] And, the firing time can be 7 to 13 hours, specifically 9 to 11 hours, but is not limited thereto.

[0217]

[0218] According to the present invention, in order to allow all excess lithium ions to participate in the reaction, the calcination may be performed under an air atmosphere.

[0219]

[0220] anode

[0221] The present invention provides a positive electrode comprising the positive electrode active material. That is, a positive electrode comprising the bimodal positive electrode active material is provided.

[0222] The positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer may include the positive electrode active material.

[0223] The positive electrode current collector may include a highly conductive metal, and is not particularly limited as long as it is easily adhered to by the positive electrode active material layer and does not react within the voltage range of the battery. The positive electrode current collector may be made of, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. In addition, the positive electrode current collector may typically have a thickness of 3 ㎛ to 500 ㎛, and fine unevenness may be formed on the surface of the current collector to increase the adhesion of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0224] The above-mentioned positive electrode active material layer may optionally include a conductive material and a binder, together with the positive electrode active material, as needed. In this case, the positive electrode active material may be included in an amount of 80 wt% to 99 wt%, more specifically 85 wt% to 98.5 wt%, based on the total weight of the positive electrode active material layer, and excellent capacity characteristics may be exhibited within this range.

[0225] The conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One of these may be used alone or a mixture of two or more may be used. The conductive material may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0226] The above binder serves to improve the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylalcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and polymers in which hydrogens of these are substituted with Li, Na, or Ca, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The above binder may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0227] The positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the positive electrode active material described above is used. Specifically, the positive electrode can be manufactured by applying a composition for forming a positive electrode active material layer, which is manufactured by dissolving or dispersing the positive electrode active material and optionally a binder, a conductive agent, and a dispersant in a solvent as needed, onto a positive electrode current collector, followed by drying and rolling, or by casting the composition for forming a positive electrode active material layer onto a separate support, peeling the film from the support, and laminating the resulting film onto a positive electrode current collector.

[0228] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant in consideration of the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0229]

[0230] lithium secondary battery

[0231] The present invention provides a lithium secondary battery including the positive electrode.

[0232]

[0233] The lithium secondary battery may include the positive electrode; the negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte. 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.

[0234] The above negative electrode may include a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0235] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 ㎛ to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0236] The above negative electrode active material layer may optionally include a binder and a conductive material together with the negative electrode active material.

[0237] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO β(0<β<2), SnO2, vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical or fibrous shapes, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes. The negative electrode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0238] The binder of the above-described negative electrode active material layer is a component that assists in bonding between the conductive material, the active material, and the current collector, and is typically added in an amount of 0.1 wt% to 10 wt% based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0239] The conductive material of the above-described negative electrode active material layer is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10 wt% or less, preferably 5 wt% or less, based on the total weight of the negative electrode active material layer. The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber or metal fiber; fluorinated carbon; metal powder such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0240] The above negative electrode can be manufactured by applying and drying a composition for forming a negative electrode active material layer prepared by dissolving or dispersing a negative electrode active material, and optionally a binder and a conductive material in a solvent, on a negative electrode current collector, or by casting the composition for forming a negative electrode active material layer on a separate support, and then laminating the film obtained by peeling it off from the support on a negative electrode current collector.

[0241] The above separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without any particular restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may also be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0242] Examples of the electrolyte include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries. As a specific example, the electrolyte may include an organic solvent and a lithium salt.

[0243] 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), ethylenecarbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes 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.

[0244] The above lithium salt can be used without any special limitation as long as it is a compound that can provide lithium ions used in a lithium secondary battery. Specifically, the anion of the above lithium salt is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - At least one selected from the group consisting of may be used, and the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. It is preferable to use the concentration of the lithium salt within the range of 0.1 M to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0245] 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 wt% to 5 wt% based on the total weight of the electrolyte.

[0246]

[0247] A lithium secondary battery including a cathode active material according to the present invention stably exhibits excellent capacity characteristics, output characteristics, and life characteristics, and is therefore useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0248] There is no particular limitation on the external shape of the lithium secondary battery of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0249] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also be preferably used as a unit battery in a medium- to large-sized battery module including a plurality of battery cells.

[0250] Accordingly, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0251] 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.

[0252]

[0253] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0254]

[0255] Examples and Comparative Examples

[0256]

[0257] Example 1

[0258] (Manufacturing of positive electrode active material precursor)

[0259] MnSO4 and NiSO4 were mixed in deionized water in an amount such that the molar ratio of Mn:Ni was 65:35 to prepare a transition metal aqueous solution with a concentration of 2.4 M, and a NaOH aqueous solution with a concentration of 25 wt% was prepared.

[0260] 2.6 L of deionized water and 3.5 ml of the above NaOH aqueous solution were added to a 10 L continuous stirring tank reactor, and the temperature was maintained at 50°C while stirring at 150 rpm to adjust the pH inside the reactor to 12.0. Nitrogen gas was purged at 2 L / min to remove dissolved oxygen and create a non-oxidizing atmosphere.

[0261] Afterwards, while stirring at 1,000 rpm, nitrogen and air were injected into the reactor at a volume ratio of 90:10 to create a weak oxidizing atmosphere, and the above transition metal aqueous solution and the above NaOH aqueous solution were continuously injected into the reactor to cause a co-precipitation reaction, thereby producing a manganese nickel hydroxide.

[0262] At this time, the above transition metal aqueous solution was introduced at a flow rate of 0.85 L / hr, and the above NaOH aqueous solution was introduced at a flow rate such that the pH within the reactor became 10.0 within 1 hour from the start of the reaction. That is, a co-precipitation reaction was performed at a pH of 12.0 to 10.0 for 1 hour from the start of the reaction to form a precursor seed.

[0263] After the pH reached 10.0, the amount of NaOH aqueous solution added was adjusted to raise and lower the pH by 0.5 every 30 minutes, and the process of raising and lowering the pH was repeated (i.e., the process of reacting at pH 10.0 for 30 minutes and then reacting at pH 10.5 for 30 minutes was repeated) to form a first shell portion (A1) by performing a co-precipitation reaction for 20 hours, and then, while maintaining the pH at 10.0, a co-precipitation reaction was performed for 40 hours to form a second shell portion (A2) (precursor particle growth process).

[0264] Afterwards, the manganese nickel hydroxide was washed with deionized water, filtered, and dried at 100°C for 12 hours to obtain a positive electrode active material precursor (composition: Mn 0.65 Ni 0.35 (OH)2) was prepared.

[0265] (Manufacturing of positive electrode active materials)

[0266] The above positive electrode active material precursor and LiOH were mixed so that the molar ratio of (Mn+Ni):Li was 1:1.3, and calcined at 900°C for 10 hours to obtain a positive electrode active material (composition: 0.26[Li2MnO3]·0.61[LiNi 0.5 Mn 0.5O2]) was manufactured. At this time, the positive electrode active material is composed of R3-m, Rhombohedral phase and C2 / m, Monoclinic phase.

[0267]

[0268] Example 2

[0269] A precursor and a positive electrode active material were manufactured in the same manner as in Example 1, except that the formation time of the first shell portion (A1) was adjusted to 10 hours and the formation time of the second shell portion (A2) was adjusted to 50 hours.

[0270]

[0271] Comparative Example 1

[0272] A precursor and a positive electrode active material were manufactured in the same manner as in Example 1, except that the formation time of the first shell portion (A1) was adjusted to 40 hours and the formation time of the second shell portion (A2) was adjusted to 20 hours.

[0273]

[0274] Comparative Example 2

[0275] (Manufacturing of positive electrode active material precursor)

[0276] MnSO4 and NiSO4 were mixed in deionized water in an amount such that the molar ratio of Mn:Ni was 65:35 to prepare a transition metal aqueous solution with a concentration of 2.4 M, and a NaOH aqueous solution with a concentration of 25 wt% was prepared.

[0277] 2.6 L of deionized water and 3.5 ml of the above NaOH aqueous solution were added to a 10 L continuous stirring tank reactor, and the temperature was maintained at 50°C while stirring at 150 rpm to adjust the pH inside the reactor to 12.0. Nitrogen gas was purged at 2 L / min to remove dissolved oxygen and create a non-oxidizing atmosphere.

[0278] Afterwards, while stirring at 1,000 rpm, nitrogen and air were injected into the reactor at a volume ratio of 90:10 to create a weak oxidizing atmosphere, and the above transition metal aqueous solution and the above NaOH aqueous solution were continuously injected into the reactor to cause a co-precipitation reaction, thereby producing a manganese nickel hydroxide.

[0279] At this time, the above transition metal aqueous solution was injected at a flow rate of 0.85 L / hr, and the above NaOH aqueous solution was injected at a flow rate such that the pH within the reactor became 10.0 within 1 hour from the start of the reaction. That is, for 1 hour from the start of the reaction, a coprecipitation reaction was performed at a pH of 12.0 to 10.0 to form precursor seeds. Thereafter, the coprecipitation reaction was performed for 60 hours while maintaining the pH at 10.0 to grow precursor particles.

[0280] Afterwards, the manganese nickel hydroxide was washed with deionized water, filtered, and dried at 100°C for 12 hours to obtain a positive electrode active material precursor (composition: Mn 0.65 Ni 0.35 (OH)2) was prepared.

[0281] (Manufacturing of positive electrode active materials)

[0282] The above positive electrode active material precursor and LiOH were mixed so that the molar ratio of (Mn+Ni):Li was 1:1.3, and calcined at 900°C for 10 hours to obtain a positive electrode active material (composition: 0.26[Li2MnO3]·0.61[LiNi 0.5 Mn 0.5 O2]) was manufactured.

[0283]

[0284] Experimental Example 1

[0285] Using a particle size analyzer (Microtrac, S3500), the average particle diameter (D) of each positive electrode active material precursor and positive electrode active material manufactured in the examples and comparative examples 50 ) was measured, and the results are shown in Table 1 below.

[0286] Specifically, 0.1 g of each of the positive electrode active material precursor and positive electrode active material sample manufactured in the examples and comparative examples was added to 0.5 ml of a dispersant and 10 ml of deionized water, dispersed for 1 minute using ultrasonic waves, and then placed in a particle size analyzer (Microtrac, S3500) and analyzed.

[0287]

[0288] Experimental Example 2

[0289] The cross-sections of each of the positive electrode active material precursors and positive electrode active materials manufactured in the examples and comparative examples were analyzed using SEM (QUANTA FEG 250, Thermo Fischer), and the results are shown in FIGS. 1 to 8. Specifically, FIG. 1 is a cross-sectional SEM image of the positive electrode active material precursor of Example 1, FIG. 2 is a cross-sectional SEM image of the positive electrode active material of Example 1, FIG. 3 is a cross-sectional SEM image of the positive electrode active material precursor of Example 2, and FIG. 4 is a cross-sectional SEM image of the positive electrode active material of Example 2. In addition, FIG. 5 is a cross-sectional SEM image of the positive electrode active material precursor of Comparative Example 1, FIG. 6 is a cross-sectional SEM image of the positive electrode active material of Comparative Example 1, FIG. 7 is a cross-sectional SEM image of the positive electrode active material precursor of Comparative Example 2, and FIG. 8 is a cross-sectional SEM image of the positive electrode active material of Comparative Example 2.

[0290] And, the diameter of the core part (A) of the positive electrode active material precursor, the thickness of the first shell part (A1), the thickness of the second shell part (A2), and the diameter of the core part (B) of the positive electrode active material, the thickness of the first shell part (B1), and the thickness of the second shell part (B2) were measured (using a length measuring tool in an SEM device), and are shown in Table 1 below.

[0291] For reference, when measuring the diameter of the core portion and the thickness of the shell portion in the positive electrode active material precursor and the positive electrode active material, the lengths were measured in various directions from the center of the particle toward the surface, and the average value was used. In the cross-sectional image, the part where the pores clearly disappeared or appeared was segmented, and the core portion, the first shell portion, and the second shell portion were distinguished by corresponding this to the reaction time during precursor synthesis.

[0292]

[0293] Cathode active material precursor Cathode active material D 50 (㎛) Core part (A) diameter (㎛) First shell part (A1) thickness (㎛) Second shell part (A1) thickness (㎛) D 50 (㎛) Core portion (B) diameter (㎛) First shell portion (B1) thickness (㎛) Second shell portion (B1) thickness (㎛) Example 19.96 3.12 2.98 0.44 9.36 3.10 2.85 0.28 Example 210.5 3.36 2.11 1.46 9.66 3.32 1.85 1.32 Comparative example 110.0 4 3.40 3.22 0.109 78 3.32 3.22 0.01 Comparative example 210.17 3.15 0.01 3.50 9.79 2.97 0.11 3.30

[0294] Referring to FIGS. 1 to 4 and Table 1, it can be confirmed that the positive electrode active material precursor and the positive electrode active material of Examples 1 and 2 each sequentially include a core portion, a shell portion (first shell portion) having relatively few pores formed on the core portion, and a shell portion (second shell portion) having relatively many pores, and it can be confirmed that the thickness of the first shell portion satisfies Equations 1 and 4 described in the present specification.

[0295] In comparison, referring to FIGS. 5 and 6 and Table 1, it can be confirmed that the positive electrode active material precursor and positive electrode active material of Comparative Example 1 have a first shell portion that is too thick and a second shell portion that is too thin. In addition, referring to FIGS. 7 and 8 and Table 1, it can be confirmed that the positive electrode active material precursor and positive electrode active material of Comparative Example 2 have a first shell portion that is almost non-existent. That is, it can be confirmed that the thickness of the first shell portion of Comparative Examples 1 and 2 does not satisfy Equations 1 and 4 described herein.

[0296]

[0297] Experimental Example 3

[0298] The tap density of each positive electrode active material precursor manufactured in the examples and comparative examples was measured and is shown in Table 2 below.

[0299] The tap density was calculated by placing 50 g of each of the positive electrode active material precursor samples manufactured in the examples and comparative examples into a cylinder, tapping the cylinder containing the sample 3000 times using Tap Denser KYT-5000 (SEISHIN), reading the scale value to measure the volume, and calculating the tap density. Each measurement was performed three times and expressed as the average value.

[0300]

[0301] Experimental Example 4

[0302] The BET specific surface area of ​​each positive electrode active material precursor and positive electrode active material manufactured in the examples and comparative examples was measured and shown in Table 2 below.

[0303] The BET surface area was measured using a surface area analyzer TriStar 2 plus (Micromeritics) using a 3.00 g sample pretreated at 200°C under vacuum conditions and the nitrogen adsorption method.

[0304]

[0305] Experimental Example 5

[0306] The pellet density of each positive electrode active material precursor manufactured in the examples and comparative examples was obtained and is shown in Table 2 below.

[0307] Specifically, the zero point for thickness was adjusted using a cylindrical mold for a circular pellet holder having a diameter of 13 mm using an automatic pellet press (Auto Pellet Press, Carver, 3887.4). Then, 3 g each of the positive electrode active materials manufactured in the examples and comparative examples was placed into the circular pellet holder, and a force was applied until a force corresponding to 2,000 kgf was reached, and the thickness of the formed pellet was measured. Then, the pellet volume was calculated using the following equation 5, and the pellet density was calculated using the following equation 6.

[0308] [Formula 5]

[0309] Pellet volume (cm) 3) = π(radius of the circular pellet holder) 2 × Pellet thickness

[0310] [Formula 6]

[0311] Pellet density (g / cm) 3 ) = Positive active material weight (g) / Pellet volume (cm 3 )

[0312]

[0313] Experimental Example 6

[0314] Each of the positive electrode active materials, conductive agent (carbon black), and binder (PVdF) manufactured in Examples and Comparative Examples was mixed in a weight ratio of 93.15:2.90:3.95 in an N-methyl-2-pyrrolidone (NMP) solvent to manufacture a positive electrode slurry. The positive electrode slurry was applied to one surface of an aluminum current collector, dried at 130°C, and then rolled to manufacture each positive electrode.

[0315] An electrode assembly was manufactured by interposing a separator between each positive electrode and a Li metal disk negative electrode manufactured as described above, and then positioning this assembly inside a battery case, and then injecting an electrolyte into the battery case to manufacture a coin cell type lithium secondary battery of the 2032 standard.

[0316] As an electrolyte, 1M LiPF6 was dissolved in an organic solvent containing ethylene carbonate: ethyl methyl carbonate: diethyl carbonate in a volume ratio of 3:3:4.

[0317] For each lithium secondary battery manufactured as described above, CC / CV mode charging was performed at 25°C with a constant current of 0.1 C to 4.6 V, then CC mode discharging was performed to 2.0 V to activate the battery, and then CC / CV mode charging was performed at a constant current of (1 / 3) C to 4.45 V, then CC mode discharging was performed to 2.15 V, and the initial charge capacity and discharge capacity were measured.

[0318] Then, the energy density value was obtained by multiplying the initial discharge capacity and the pellet density value of the positive electrode active material.

[0319]

[0320] Cathode active material precursor Cathode active material BET specific surface area (m 2 / g)Tab density (g / cm) 3 )BET specific surface area (m 2 / g) Pellet density (g / cm) 3 ) Energy density (mAh / cm 3 )Example 118.41.860.352.572011.03Example 224.51.750.922.501880.1Comparative Example 118.51.880.322.501738.2Comparative Example 225.61.631.352.311681.9

[0321] Referring to Tables 1 and 2, the positive electrode active material precursors of Examples 1 and 2 have a thickness of the first shell portion that satisfies Equation 1 described herein and a tap density of 1.75 g / cm 3 2.0g / cm 3 , and the BET surface area is 18m 2 / g to 25m 2 / g, and the positive electrode active materials of Examples 1 and 2 have a thickness of the first shell portion that satisfies Equation 4 described herein, and a pellet density of 2.5 g / cm 3 3.00g / cm 3 and the BET surface area is 0.20 m 2 / g to 1.0m 2 It can be confirmed that / g is satisfied. From this, it can be confirmed that the energy density of the positive electrode active material manufactured from the positive electrode active material precursor according to the present invention is high.

[0322] In comparison, it can be confirmed that the positive electrode active material manufactured from the positive electrode active material precursor of Comparative Examples 1 and 2 has a low energy density.

Claims

1. Contains manganese-nickel hydroxide containing manganese and nickel, The manganese nickel-based hydroxide comprises a porous core portion (A); a first shell portion (A1) formed on the core portion; and a porous second shell portion (A2) formed on the first shell portion. The thickness of the first shell portion (A1) satisfies the following equation 1: Tap density is 1.75g / cm 3 2.0 g / cm 3 , and the BET surface area is 18m 2 / g to 25m 2 / g positive electrode active material precursor: [Formula 1] 0.15×(average particle size of manganese nickel hydroxide (D 50 )) < thickness of the first shell (A1) < 0.30×(average particle size of manganese nickel hydroxide (D 50 )).

2. In claim 1, The diameter of the core portion (A) above satisfies the following equation 2: [Formula 2] 0 < diameter of core (A) < (average particle diameter of manganese nickel hydroxide (D) 50 )) / 3.

3. In claim 1, The thickness of the second shell portion (A2) satisfies the following equation 3: [Formula 3] 0.04×(Average particle size of manganese nickel hydroxide (D 50 )) ≤ thickness of the second shell (A2) ≤ 0.15×(average particle size of manganese nickel hydroxide (D 50 )).

4. In claim 1, The above manganese nickel hydroxide is a cathode active material precursor containing manganese in an amount of 50 mol% or more among the total transition metals.

5. In claim 1, The manganese nickel hydroxide is a positive electrode active material precursor having a composition represented by the following chemical formula 1: [Chemical Formula 1] [Mn a1 No b1 M c1 ](OH) 2 In the above chemical formula 1, M is at least one selected from Zr, Al, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, W, Na and Pt, 0.5≤a1<1.0, 0 <b1≤0.5, 0≤c1≤0.1, a1+b1+c1=1이다.

6. In claim 1, The above manganese nickel hydroxide has an average particle size (D 50 ) is a positive electrode active material precursor having a diameter of 1 μm to 15 μm.

7. In claim 1, The diameter of the above core portion (A) is 0.33㎛ or more and less than 5㎛, The thickness of the above first shell portion (A1) is 0.3 ㎛ or more and 4.5 ㎛ or less, A positive electrode active material precursor having a thickness of the second shell portion (A2) of 0.05 ㎛ or more and 0.75 ㎛ or less.

8. (S1) A step of adding a solvent and a basic solution to a reactor to adjust the pH to 12.0 to 13.0, and then purging an inert gas to create a non-oxidizing atmosphere; (S2) A step of continuously adding a transition metal-containing solution including manganese and nickel and a basic solution to a reactor and performing a co-precipitation reaction at a pH of 12.0 to 13.0 to form a porous core portion (A); (S3) (S2) A step of continuously adding a transition metal-containing solution including manganese and nickel and a basic solution to a reactor that has gone through the step, and repeating the process of lowering the pH by 0.25 to 0.5 every 20 to 60 minutes at a pH of 10.0 to 11.0 and then restoring it to the original state, thereby performing a co-precipitation reaction to form a first shell part (A1) on the porous core part (A); and (S4) A step of continuously introducing a transition metal-containing solution containing manganese and nickel and a basic solution into a reactor that has undergone step (S3), and performing a co-precipitation reaction at a pH of 10.0 to 11.0 to form a porous second shell part (A2) on the first shell part (A1), thereby producing a manganese-nickel hydroxide containing manganese and nickel; The above steps (S2) to (S4) are performed under an oxidizing atmosphere, A method for producing a positive electrode active material precursor, wherein the co-precipitation reaction of the above step (S3) is performed for 5 to 25 hours.

9. In claim 8, A method for producing a positive electrode active material precursor, wherein the co-precipitation reaction of the above step (S2) is performed for 0.1 to 2.0 hours.

10. In claim 8, A method for producing a positive electrode active material precursor, wherein the co-precipitation reaction of the above step (S4) is performed for 35 to 55 hours.

11. In claim 8, A method for producing a cathode active material precursor, wherein the above oxidizing atmosphere is created by introducing air and an inert gas into a reactor.

12. In claim 8, A method for manufacturing a positive electrode active material precursor, wherein the above atmosphere and inert gas are introduced in a volume ratio of 0.5:99.5 to 15:

85.

13. Containing a lithium-excess manganese-nickel oxide containing manganese and nickel, The above lithium-excess manganese nickel oxide is Li 2 MnO 3 Prize and LiMO 2 (At this time, M includes at least one selected from Ni and Mn) and includes the award at the same time, The lithium-excess manganese nickel oxide comprises a porous core portion (B); a first shell portion (B1) formed on the core portion; and a porous second shell portion (B2) formed on the first shell portion. The thickness of the first shell portion (B1) satisfies the following equation 4: Pellet density is 2.5g / cm 3 3.00g / cm2 3 And, BET surface area is 0.20m 2 / g to 1.0m 2 / g positive electrode active material: [Formula 4] 0.15×(Average particle size of lithium-excess manganese nickel oxide (D 50 )) < thickness of the first shell (B1) < 0.32×(average particle size of lithium-excess manganese nickel oxide (D 50 )).

14. In claim 13, The above lithium-excess manganese nickel oxide is a cathode active material containing manganese in an amount of 50 mol% or more among all transition metals excluding lithium.

15. In claim 13, The above lithium-excess manganese nickel oxide is a cathode active material having a composition represented by the following chemical formula 2: [Chemical formula 2] xLi 2 Mn (1-p) M 1 p O 3 ·(1-x)LiNi q Mn r M 2 s O 2 In the above chemical formula 2, M 1 and M 2 are each independently at least one selected from Zr, Al, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, W, Na and Pt, 0 <x<1.0, 0≤p≤0.1, 0<q≤0.5, 0.5≤r<1.0, 0≤s≤0.1, q+r+s=1이다.

16. A method for producing a cathode active material, comprising the step of mixing a cathode active material precursor according to claim 1 and a lithium raw material, and then calcining.

17. In claim 16, A method for producing a cathode active material, wherein the cathode active material precursor and the lithium raw material are mixed so that the molar ratio of the total metal elements present in the cathode active material precursor and the lithium present in the lithium raw material is 1:1.2 to 1:1.

6.

18. In claim 16, A method for producing a positive electrode active material, wherein the above-mentioned calcination is performed at 850°C to 950°C.

Images