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

Abstract

The present invention relates to a cathode active material which comprises a lithium nickel-based oxide containing 80 mol% or more of nickel from total metals excluding lithium, and which has a particle strength of 260-390 MPa.

Description

Cathode active material, precursor for cathode active material, method for manufacturing a precursor for cathode active material, cathode material, cathode and lithium secondary battery

[0001] Cross-citation with related applications

[0002] The present application claims the benefit of priority based on Korean Patent Application No. 10-2024-0196803 filed on December 26, 2024, and Korean Patent Application No. 10-2025-0210148 filed on December 24, 2025, and all contents disclosed in said Korean patent application documents are incorporated herein as part of the specification.

[0003] Technology field

[0004] The present invention relates to a positive electrode active material, a precursor for a positive electrode active material, a method for manufacturing a precursor for a positive electrode active material, a positive electrode material, a positive electrode, and a lithium secondary battery. More specifically, the invention relates to a positive electrode active material with reduced particle breakage during rolling, a precursor for a positive electrode active material, a method for manufacturing a precursor for a positive electrode active material, a positive electrode material, a positive electrode, and a lithium secondary battery.

[0005]

[0006] With the technological advancement of electric vehicles and portable electronic devices, the demand for lithium-ion batteries as an energy source is rapidly increasing. In particular, due to recent advancements in electric vehicle technology, there is a demand for batteries with high energy density.

[0007] As one of the technologies to increase the energy density of lithium secondary batteries, a technology has been developed to apply a cathode material having a bimodal structure in which a cathode active material having a large particle size is mixed with a cathode active material having a small particle size. Specifically, in a lithium secondary battery applying a cathode material having a bimodal structure, the energy density of the cathode can be improved because the small-particle cathode active material can fill the voids between the large-particle cathode active material particles.

[0008] In addition, by rolling an anode containing such a bimodal structured anode material, an anode with a denser structure can be manufactured, thereby further improving the energy density of the anode. However, during the rolling process, breakage of the anode active material particles may occur, and such particle breakage can lead to problems such as degradation of the anode active material.

[0009] Therefore, a technology has recently been developed to further increase rolling density while reducing particle breakage of the small-particle cathode active material by applying single-particle type particles with excellent particle strength as the small-particle cathode active material included in the bimodal structured cathode material.

[0010] Meanwhile, when secondary particles are applied as conventional small-particle cathode active materials, the small-particle cathode active material has relatively weaker particle strength than the large-particle cathode active material; thus, during the rolling process, the small-particle cathode active material particles break first and act as a buffer, preventing particle breakage of the large-particle cathode active material. However, as described above, when single-particle type particles are applied to the small-particle cathode active material, particle breakage of the large-particle cathode active material increases as the particle strength of the small-particle cathode active material increases, which can cause problems such as deterioration of battery life and resistance characteristics, increased gas generation, and reduced thermal stability.

[0011] Therefore, there is a need to develop technology capable of solving these problems.

[0012]

[0013] The present invention aims to solve the aforementioned problems by providing a precursor for an anode active material that can be applied to a bimodal structured anode material to prevent particle breakage during rolling, a method for manufacturing such a precursor for an anode active material, and an anode active material. Furthermore, the present invention aims to provide an anode material, an anode, and a lithium secondary battery in which the anode active material is included as a large-particle anode active material, thereby minimizing particle breakage during rolling and improving energy density.

[0014]

[0015] [1] The present invention provides a positive electrode active material comprising a lithium nickel-based oxide containing 80 mol% or more of nickel among all metals excluding lithium, and having a particle strength of 260 MPa to 390 MPa.

[0016] [2] The present invention, in [1] above, has an average particle size (D) of the positive active material. 50 ) provides a positive electrode active material having a size of 5㎛ to 18㎛.

[0017] [3] The present invention provides a positive active material according to [1] or [2], wherein the positive active material has a span value of 0.2 to 0.7 defined by the following formula C.

[0018] [Equation C]

[0019] SPAN = (D 90 -D 10 ) / D 50

[0020] In the above equation C, D 90, D 50, D 10 These are the particle size values ​​when the cumulative volume is 90%, 50%, and 10%, respectively, in the volume-based particle size distribution of the above-mentioned positive active material.

[0021] [4] The present invention provides a positive active material, wherein in any one of [1] to [3], the positive active material comprises secondary particles.

[0022] [5] The present invention provides a precursor for an anode active material comprising a nickel-based hydroxide containing 80 mol% or more of nickel among the total metals, and having a particle strength of 70 to 90 MPa.

[0023] [6] In the present invention, the precursor for the positive electrode active material according to [5] has an average particle size (D 50 Provides a precursor for a positive electrode active material having a thickness of 5㎛ to 18㎛.

[0024] [7] The present invention comprises a nucleation step of forming a precursor nucleus for an anode active material by co-precipitating a transition metal aqueous solution, an ammonium cation complex forming agent, and a basic compound while supplying them to a reactor; and

[0025] The present invention provides a method for manufacturing a precursor for a positive electrode active material, comprising: a particle growth step in which a transition metal aqueous solution, an ammonium cation complex forming agent, and a basic compound are supplied to a reaction solution in which a precursor nucleus for a positive electrode active material is formed, and a co-precipitation reaction is carried out to grow precursor particles for a positive electrode active material; wherein, in the particle growth step, the transition metal aqueous solution is supplied at a first flow rate of 8 L / h to 11.5 L / h and then supplied at a second flow rate of 20 L / h to 30 L / h.

[0026] [8] The present invention provides a method for manufacturing a precursor for an anode active material, wherein, in the particle growth step of [7], the co-precipitation reaction is performed at a temperature of 46 to 59°C.

[0027] [9] The present invention provides a method for manufacturing a precursor for an anode active material, wherein, in the particle growth step of [7] or [8], the transition metal aqueous solution is supplied at a first flow rate for 2 hours or less, and then supplied at a second flow rate for 7 to 13 hours.

[0028]

[0010] The present invention provides a method for manufacturing a precursor for an anode active material, wherein, in at least one of [7] to [9], the second flow rate is 2.3 times or more the first flow rate.

[0029]

[0011] The present invention comprises a first positive electrode active material; and a second positive electrode active material; wherein the first positive electrode active material has an average particle size (D) greater than that of the second positive electrode active material. 50 ) is large, and the first positive active material is a positive active material according to any one of [1] to [4], providing a positive material.

[0030]

[0012] The present invention provides a cathode material in which, in

[0011] the second cathode active material comprises a single particle.

[0031]

[0013] The present invention provides a cathode material according to

[0011] or

[0012] , wherein the second cathode active material comprises a lithium nickel-based oxide containing 80 mol% or more of nickel among the total metals excluding lithium.

[0032]

[0014] The present invention, in at least one of

[0011] to

[0013] , wherein the average particle size (D) of the second positive active material 50 ) provides a cathode material having a thickness of 1㎛ to 5㎛.

[0033]

[0015] The present invention provides a cathode material in which, in at least one of

[0011] to

[0014] , the second cathode active material has a ratio of particles with a particle size of 1 μm or less of 3.0 volume% or less.

[0034]

[0016] The present invention provides a cathode material in which, in at least one of

[0011] to

[0015] , the second cathode active material has a particle strength of 600 MPa to 900 MPa.

[0035]

[0017] The present invention provides a cathode material in which, in at least one of

[0011] to

[0016] , the second cathode active material has a span value of 0.7 to 1.5 as defined by the following formula C-1.

[0036] [Equation C-1]

[0037] SPAN = (D 90 -D 10 ) / D 50

[0038] In the above equation C-1, D 90, D 50, D 10 These are the particle size values ​​when the cumulative volume is 90%, 50%, and 10%, respectively, in the volume-based particle size distribution of the second positive active material.

[0039]

[0018] The present invention provides a cathode material in which, in at least one of

[0011] to

[0017] , the first cathode active material and the second cathode active material are included in a weight ratio of 2:8 to 8:2.

[0040]

[0019] The present invention provides an anode comprising an anode material according to at least one of

[0011] to

[0018] .

[0041]

[0020] The present invention provides a lithium secondary battery comprising: a positive electrode according to

[0019] ; a negative electrode disposed opposite to the positive electrode; and an electrolyte.

[0042]

[0043] The positive electrode active material according to the present invention satisfies a specific range of particle strength. Accordingly, the positive electrode active material according to the present invention can sufficiently withstand pressure even when pressure is concentrated on the positive electrode active material during rolling, thereby reducing particle breakage; at the same time, it can sufficiently disperse stress generated inside the positive electrode active material during charging and discharging, and secure electrolyte impregnation properties.

[0044] In particular, this particle breakage reduction effect can be maximized when the above-mentioned cathode active material is applied as a large-particle cathode active material in a bimodal structured cathode material. Specifically, when the above-mentioned cathode active material is included as a large-particle cathode active material in a bimodal structured cathode material, pressure may be concentrated on the large-particle cathode active material during rolling due to the difference in relative particle strength with respect to the small-particle cathode active material, such as by including single-particle type particles. Since the cathode active material according to the present invention possesses sufficient strength to withstand concentrated pressure during rolling, it can improve the problem of excessive breakage occurring in the large-particle cathode active material particles. Accordingly, particle breakage or cracking occurring in both the small-particle cathode active material and the large-particle cathode active material during rolling can be minimized, and rolling density can be improved at the same time.

[0045] The positive electrode active material according to the present invention may be manufactured using a precursor for a positive electrode active material manufactured by the method for manufacturing a precursor for a positive electrode active material according to the present invention. Accordingly, the particle strength of the positive electrode active material can be controlled to satisfy a specific range.

[0046] Consequently, when the cathode material according to the present invention is applied to a cathode and a lithium secondary battery, energy density is improved, capacity and resistance characteristics are excellent, and high-temperature life characteristics and gas generation can be reduced.

[0047]

[0048] The present invention will be described in more detail below.

[0049] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0050] The terms used in this specification are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0051] In this specification, terms such as “comprising,” “having,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0052] In the present invention, "single-particle type particle" refers to a particle formed by the aggregation of 30 or fewer sub-particles. The sub-particle unit constituting the single-particle type particle shall be referred to as a nodule. Single-particle type particles include a single particle consisting of one nodule and a pseudo-single particle which is a composite of 2 to 30 nodules.

[0053] The above “nodule” is a sub-grain unit constituting a single particle and a pseudo-single particle, and may be a single crystal that does not have crystalline grain boundaries, or a polycrystalline one in which no grain boundaries appear to exist when observed at a field of view of 5,000 to 20,000 times using a scanning electron microscope.

[0054] In the present invention, "secondary particle" refers to a particle formed by the aggregation of more than 30 sub-particles. To distinguish it from the sub-particles constituting a single-particle type particle, the sub-particles constituting the secondary particle are called "primary particles."

[0055] In the present invention, the term “particle” is a concept that includes any one or all of a single particle, a pseudo-single particle, a primary particle, a nodule, and a secondary particle.

[0056] In the present invention, "average particle size D 50 "This refers to the particle size corresponding to 50% of the volume-based particle size distribution of the powder to be measured, and can be measured using the laser diffraction method. For example, the powder to be measured can be measured by dispersing it in a dispersion medium, introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasound of about 28 kHz at an output of 60 W, obtaining a volume-based particle size distribution graph, and then determining the particle size corresponding to 50% of the volume-based particle size.

[0057] In the present invention, “particle strength” can be defined as compressive fracture strength. The positive electrode active material undergoes a rolling process as one of the manufacturing processes. At this time, the rolling process refers to pressing the electrode active material layer several times under a predetermined pressure to increase electrode density and enhance crystallinity. During the rolling process, some positive electrode active material particles may break and be destroyed because they cannot withstand the compressive stress received during rolling. Accordingly, particle strength can be quantified by measuring the force at the point where cracks occur in the particles when force is applied to the positive electrode active material particles.

[0058] For example, in this specification, “particle strength” can be measured as the arithmetic mean value of particle strengths obtained by applying pressure perpendicular to the target particle using Anton Paar’s Surface testing Platform_step 300 equipment to measure the point at which a crack occurs in the particle, calculating the particle strength according to the following [Equation A], and repeating this 10 times.

[0059] [Equation A]

[0060]

[0061] In the above [Equation A],

[0062] P refers to the pressure applied perpendicular to the particle at the point where a crack occurs in the target particle.

[0063] D represents the diameter of the particle assuming that the particle is a perfect sphere, and can be calculated as the arithmetic mean of the horizontal diameter and the vertical diameter of the particle. In this case, the diameter of the particle can be measured from a Scanning Electron Microscope (SEM) image of the particle taken using a SEM.

[0064] μ represents Poisson's ratio, and the normal strain (R) of the diameter of the particle is v ) and horizontal strain (R p It can be defined as the ratio of ).

[0065] The normal strain (R) of the diameter of the above particle v ) can be calculated according to the following [Equation B-1].

[0066] [Equation B-1]

[0067]

[0068] In the above [Equation B-1], D0 represents the diameter in the vertical direction of the particle before applying pressure to the particle, and D v represents the diameter in the vertical direction of the positive active material particle at the point where cracks occur in the particle.

[0069] Horizontal strain (R) of the diameter of the above particle p ) can be calculated according to the following [Equation B-2]. However, since horizontal deformation of the particle may not be considered when calculating the Poisson ratio, the above horizontal strain (R p ) can be calculated as 1.

[0070] [Equation B-2]

[0071]

[0072] In the above [Equation B-2], D1 represents the horizontal diameter of the particle before applying pressure to the particle, and D p represents the horizontal diameter of the particle at the point where a crack occurs in the particle.

[0073] In this specification, D 90, D 50, D 10 Each refers to a particle size corresponding to 90% of the volume-based particle size distribution of the positive active material powder, and can be measured using a laser diffraction method. For example, after dispersing the positive active material powder in a dispersion medium, it can be introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiated with ultrasound of approximately 28 kHz at an output of 60 W, and then obtained a volume-based particle size distribution graph, and then measured by determining the particle sizes corresponding to 90%, 50%, and 10% of the volume-based particle size distribution.

[0074]

[0075] In this specification, “ratio of particles with a particle size of 1 μm or less” refers to the volume percentage of particles with a particle size of 1 μm or less based on the total weight of the positive active material powder when the positive active material is pressed with a force of 12 tons. For example, the fine particle generation rate can be obtained by placing the positive active material in powder form into a cylindrical metal mold with a diameter of 13 mm, pressing it with a force of 12 tons, then dispersing it again in a dispersion medium, obtaining a Particle Size Distribution (PSD) using a laser diffraction particle size measuring device (Malvern, Mastersizer 3000), and then calculating the volume ratio of particles with a particle size of 1 μm or less in the total positive active material powder.

[0076]

[0077] The present invention will be described in more detail below.

[0078] The precursor for a positive electrode active material, the method for manufacturing the precursor for a positive electrode active material, the positive electrode active material, the positive electrode material, and the lithium secondary battery according to the present invention comprise at least one of the configurations disclosed below, and may comprise any combination of technically feasible configurations among the configurations below.

[0079]

[0080] A cathode material having a bimodal structure has a structure in which small-particle cathode active material and large-particle cathode active material are mixed. During electrode rolling, the small-particle cathode active material fills the pores of the large-particle cathode active material, thereby increasing electrode density and enabling the realization of high energy density. Conventionally, in cathode materials having a bimodal structure, large-particle cathode active material and small-particle cathode active material were applied in the form of secondary particles. However, when charging and discharging are repeated, cracks occur between the primary particles, resulting in low structural stability, and there was a problem that lifespan characteristics deteriorated due to side reactions with the electrolyte.

[0081] Accordingly, the aim was to improve structural stability and reduce adverse reactions with the electrolyte by introducing a single-particle form into the bimodal cathode active material. However, since single-particle particles present a problem where resistance increases as the lithium diffusion distance lengthens as the average particle size of the cathode active material increases, the resistance issue was improved by applying a small-particle cathode active material as a single particle instead of a large-particle material, and the rolling density was also enhanced.

[0082] However, when using conventional small-particle cathode active materials in the form of secondary particles, the small-particle cathode active material would break first during electrode rolling, acting as a buffer for the large-particle cathode active material and preventing particle breakage of the large-particle cathode active material. However, when using single-particle type particles as the small-particle cathode active material, as the particle strength of the small-particle cathode active material increases, the small-particle cathode active material cannot act as a buffer, and the force becomes concentrated on the large-particle cathode active material during rolling, resulting in a problem where particle breakage of the large-particle cathode active material actually increases during electrode rolling. Consequently, this led to an increase in gas generation due to side reactions between the large-particle cathode active material and the electrolyte, a decrease in resistance characteristics, and a deterioration in the battery life characteristics.

[0083] Accordingly, the inventors conducted extensive research to solve the problem of particle breakage of large-particle cathode active materials during rolling in a bimodal structured cathode material comprising a small-particle cathode active material in the form of a single particle. As a result, the inventors confirmed that the particle strength of the cathode active material can be controlled when manufacturing the cathode active material by supplying an aqueous transition metal solution at a specific flow rate during the particle growth stage. From this, the inventors discovered that by controlling the particle strength of the large-particle cathode active material to a specific range and applying it to a bimodal structured cathode material, particle breakage during rolling of the large-particle cathode active material can be minimized. Consequently, the inventors found that excellent resistance characteristics and energy density can be achieved while suppressing the degradation and gas generation of the cathode material caused by particle cracking and breakage, thereby completing the present invention.

[0084]

[0085] The present invention will be described in detail below.

[0086] The positive electrode active material, the precursor for the positive electrode active material, the method for manufacturing the precursor for the positive electrode active material, the positive electrode material, the positive electrode, and the lithium secondary battery according to the present invention comprise at least one of the configurations disclosed below and may comprise any combination of technically feasible configurations among the configurations below.

[0087]

[0088] Precursor for positive electrode active material

[0089] The precursor particles for the positive electrode active material according to the present invention include a nickel-based hydroxide.

[0090] The above nickel-based hydroxide may contain nickel.

[0091] The above nickel-based hydroxide may contain nickel in an amount of 80 mol% or more, 82 mol% or more, 85 mol% or more, 88 mol% or more, 90 mol% or more, 92 mol% or more, 95 mol% or more, 97 mol% or more, 99 mol% or less, or 98 mol% or less among the total metals. For example, the above nickel-based hydroxide may contain nickel in an amount of 80 mol% or more, 85 mol% or more and 99 mol% or less, 90 mol% or more and 99 mol% or less, or 95 mol% or more and 98 mol% or less among the total metals. If the above ranges are satisfied, the capacity characteristics of the manufactured cathode active material may be excellent.

[0092] The above nickel-based hydroxide may further contain cobalt.

[0093] The above nickel-based hydroxide may contain cobalt in an amount of 0.1 mol% or more, 0.2 mol% or more, 0.3 mol% or more, 0.4 mol% or more, 0.5 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 8 mol% or less, 5 mol% or less, 1 mol% or less, 0.8 mol% or less, or 0.5 mol% or less among the total metals. For example, the above nickel-based hydroxide may contain cobalt in an amount of 20 mol% or less, 10 mol% or less, 5 mol% or less, 1 mol% or less, or 0.1 mol% or more and 1 mol% or less among the total metals. When the above ranges are satisfied, output characteristics can be secured.

[0094] The above nickel-based hydroxide may further contain manganese.

[0095] The above nickel-based hydroxide may contain manganese in the total metal in an amount of 0.1 mol% or more, 0.5 mol% or more, 1 mol% or more, 1.5 mol% or more, 2 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 8 mol% or less, 5 mol% or less, 3 mol% or less, or 2 mol% or less. For example, the above nickel-based hydroxide may contain manganese in the total metal in an amount of 20 mol% or less, 15 mol% or less, 10 mol% or less, or 1 mol% or more and 5 mol% or less. Structural stability can be secured when the above ranges are satisfied.

[0096] The above nickel-based hydroxide may further include aluminum.

[0097] The nickel-based hydroxide may contain aluminum in an amount of 0.1 mol% or more, 0.5 mol% or more, 1 mol% or more, 1.5 mol% or more, 2 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 8 mol% or less, 5 mol% or less, 3 mol% or less, 2 mol% or less, or 1 mol% or less among the total metals. For example, the nickel-based hydroxide may contain aluminum in an amount of 20 mol% or less, 15 mol% or less, 10 mol% or less, or 0.1 mol% or more and 5 mol% or less among the total metals. When the above ranges are satisfied, output characteristics and structural stability can be secured.

[0098] The nickel-based hydroxide may further include a doping element. The doping element may be one or more selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, or one or more selected from the group consisting of W, Y, Ba, Ca, Ti, Mg, Ta, and Nb.

[0099] The nickel-based hydroxide may contain the doping element in an amount of 0.1 mol% or more, 0.2 mol% or more, 0.3 mol% or more, 0.4 mol% or more, 0.5 mol% or more and 10 mol% or less, 8 mol% or less, 5 mol% or less, 1 mol% or less, 0.8 mol% or less, or 0.5 mol% or less of the total metal. For example, the nickel-based hydroxide may contain the doping element in an amount of 10 mol% or less, 8 mol% or less, 5 mol% or less, or 1 mol% or less of the total metal. If the above ranges are satisfied, ease of sintering or output characteristics and structural stability can be improved.

[0100] Alternatively, the nickel-based hydroxide may be represented by the following chemical formula 1.

[0101] [Chemical Formula 1]

[0102] Ni x0 Co y0 M 1 z0 M 2 w0 (OH)2

[0103] In the above chemical formula 1, M 1 It can be Mn, Al, or a combination thereof.

[0104] In the above chemical formula 1, M 2 ... may be one or more doping elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, or may be one or more doping elements selected from the group consisting of W, Y, Ba, Ca, Ti, Mg, Ta, and Nb. 2 It may be optionally included in or not included in the nickel-based hydroxide represented by the above chemical formula 1, and if included, it may play a role in facilitating calcination or improving structural stability.

[0105] The above x0 represents the molar ratio of nickel to the total metal in the nickel-based hydroxide particles, and may be 0.8≤x0<1.0, 0.85≤x0≤0.99, 0.90≤x0≤0.99, or 0.95≤x0≤0.98. When the above range is satisfied, the capacity characteristics of the manufactured cathode active material may be excellent.

[0106] The above y0 refers to the molar ratio of cobalt among the total metals in the nickel-based hydroxide particles, where 0 <y0≤0.2, 0<y0≤0.1, 0<y0≤0.05, 또는 0<y0≤0.01일 수 있다. 상기 범위를 만족하는 경우, 비용적인 이점을 가지면서, 출력 특성이 개선될 수 있다.

[0107] The above z0 is M among the total metals in the nickel-based hydroxide particles. 1 It refers to the molar ratio of, 0 <z0≤0.2, 0<z0≤0.15, 0<z0≤0.1, 또는 0.01≤z0≤0.05일 수 있다. 상기 범위를 만족하는 경우, 제조된 양극 활물질의 구조적 안정성이 개선될 수 있다.

[0108] The above w0 is M among the total metals in the nickel-based hydroxide particles. 2 It refers to the molar ratio, which may be 0≤w0≤0.1, 0≤w0≤0.08, 0≤w0≤0.05, or 0≤w0≤0.01. When the above range is satisfied, it can play a role in promoting particle growth during calcination of the manufactured cathode active material or improving crystal structure stability.

[0109] Alternatively, the nickel-based hydroxide may be represented by the following chemical formula 1-1.

[0110] [Chemical Formula 1-1]

[0111] Ni x1 Co y1 Mn z1 M 3 w1 (OH)2

[0112] In the above chemical formula 1-1, M 3... may be one or more doping elements selected from the group consisting of Al, W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and preferably may be one or more doping elements selected from the group consisting of Al, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb. 3 It may be optionally included in or not included in the nickel-based hydroxide represented by the above chemical formula 1-1, and if included, it may play a role in facilitating calcination or improving structural stability.

[0113] The above x1 represents the molar ratio of nickel in nickel-based hydroxide particles, and may be 0.8≤x1<1.0, 0.85≤x1≤0.99, 0.90≤x1≤0.99, or 0.95≤x1≤0.98. When the above range is satisfied, the capacity characteristics of the manufactured cathode active material may be excellent.

[0114] The above y1 refers to the molar ratio of cobalt in nickel-based hydroxide particles, 0 <y1≤0.2, 0<y1≤0.1, 0<y1≤0.05, 또는 0<y1≤0.01일 수 있다. 상기 범위를 만족하는 경우, 비용적인 이점을 가지면서, 출력 특성이 개선될 수 있다.

[0115] The above z1 refers to the molar ratio of manganese in nickel-based hydroxide particles, 0 <z1≤0.2, 0<z1≤0.15, 0<z0≤0.1, 또는 0.01≤z1≤0.05일 수 있다. 상기 범위를 만족하는 경우, 제조된 양극 활물질의 구조적 안정성이 개선될 수 있다.

[0116] The above w1 is M in nickel-based hydroxide particles 3It refers to the molar ratio of 0≤w1≤0.1, 0≤w1≤0.08, 0≤w1≤0.05, or 0≤w1≤0.01. If the above range is satisfied, the structural stability of the manufactured cathode active material can be improved.

[0117]

[0118] The particle strength of the above-described precursor for the positive active material is 70 MPa to 90 MPa. The particle strength can be controlled by controlling the internal structure and porosity of the precursor for the positive active material by adjusting the flow rate, temperature, reaction time, etc. of the transition metal aqueous solution during the co-precipitation reaction in the aforementioned method for manufacturing the precursor for the positive active material. Specifically, the particle strength of the above-described precursor for the positive active material may be 70 MPa or more, 75 MPa or more, 80 MPa or more, 90 MPa or less, 85 MPa or less, or 80 MPa or less. For example, the particle strength of the above-described precursor for the positive active material may be 70 MPa to 90 MPa, or 75 MPa to 85 MPa. The particle strength of the positive active material may be influenced by the particle strength of the applied precursor for the positive active material. Accordingly, if the particle strength of the precursor for the positive electrode active material satisfies the above range, the positive electrode active material manufactured by calcining the precursor for the positive electrode active material can have a particle strength within a specific range. Accordingly, even if the manufactured precursor for the positive electrode active material is mixed with a small-particle positive electrode active material in the form of single particles and applied to the positive electrode, it can withstand pressure during positive electrode rolling, and particle breakage occurring in large-particle positive electrode active materials can be reduced.

[0119]

[0120] The above precursor for the positive electrode active material has an average particle size (D 50) may be 5㎛ or more, 5.5㎛ or more, 6㎛ or more, 6.5㎛ or more, 7㎛ or more, 7.5㎛ or more, 8㎛ or more, 8.5㎛ or more, 9㎛ or more, 9.5㎛ or more, 10㎛ or more, 10.5㎛ or more, 11㎛ or more, 11.5㎛ or more, 12㎛ or more, 18㎛ or less, 17.5㎛ or less, 17㎛ or less, 16.5㎛ or less, 16㎛ or less, 15.5㎛ or less, 15㎛ or less, 14.5㎛ or less, 14㎛ or less, 13.5㎛ or less, 13㎛ or less, 12.5㎛ or less, or 12㎛ or less. For example, the above precursor for the cathode active material may have an average particle size (D 50 The particle size may be 5㎛ to 18㎛, 7㎛ to 16㎛, 9㎛ to 15㎛, or 11㎛ to 13㎛. When the above range is satisfied, the cathode active material manufactured by calcining the cathode active material precursor may have an appropriate particle size, which can increase the rolling density when applied to the cathode, and accordingly, the electrode density is improved, thereby enabling excellent energy density.

[0121]

[0122] Method for manufacturing a precursor for a positive electrode active material

[0123] A method for manufacturing a precursor for an anode active material according to the present invention comprises: a nucleation step of forming a precursor nucleus for an anode active material by co-precipitating a reaction while supplying an aqueous transition metal solution, an ammonium cation complex forming agent, and a basic compound to a reactor; and a particle growth step of growing precursor particles for an anode active material by co-precipitating a reaction while supplying an aqueous transition metal solution, an ammonium cation complex forming agent, and a basic compound to a reaction solution in which the precursor nucleus for the anode active material is formed.

[0124] In the particle growth step, the transition metal aqueous solution is supplied at a first flow rate of 8 L / h to 12 L / h, and then supplied at a second flow rate of 20 L / h to 30 L / h.

[0125]

[0126] In the process of manufacturing lithium secondary batteries, a rolling process is performed to press the positive active material layer under a predetermined pressure to increase energy density. However, during this rolling process, particle breakage occurs in which the positive active material fails to withstand the pressure and its particles are destroyed. When particle breakage occurs, the contact area between the positive active material and the electrolyte increases, leading to an increase in gas generation due to side reactions with the electrolyte and an increase in initial resistance. Additionally, as the positive active material degrades during repeated charging and discharging cycles, thermal stability decreases, and problems such as reduced lifespan and high-temperature lifespan characteristics may arise.

[0127] To solve this problem, it is necessary to appropriately adjust the particle strength of the positive electrode active material to a range capable of withstanding the pressure during rolling. Accordingly, the inventors discovered that the particle strength of the positive electrode active material precursor can be controlled to a desired range by adjusting the flow rate of the transition metal aqueous solution during the co-precipitation reaction to a specific range during the manufacturing step of the positive electrode active material precursor, and thus completed the present invention. The positive electrode active material manufactured by calcining the above-mentioned positive electrode active material precursor has appropriate particle strength and can sufficiently withstand pressure even during rolling, thereby reducing particle breakage.

[0128] The above-mentioned cathode active material can be applied as a large-particle cathode active material in a cathode material having a bimodal structure. In this case, particle breakage of the large-particle cathode active material can be minimized during electrode rolling, thereby preventing degradation of the large-particle cathode active material, suppressing gas generation, improving thermal stability, and improving the lifespan and resistance characteristics of the battery.

[0129]

[0130] Hereinafter, each step of the method for manufacturing a precursor for a positive electrode active material according to the present invention will be described in detail.

[0131]

[0132] (1) Nucleation stage

[0133] An aqueous transition metal solution, an ammonium cation complex forming agent, and a basic compound are supplied to a reactor and subjected to a co-precipitation reaction to form a precursor nucleus for the cathode active material.

[0134] It is preferable that the above reactor be a batch reactor. This is because it is difficult to control the particle size of the precursor particles when manufacturing the precursor using a Continuous Stirred-Tank Reactor (CSTR).

[0135] The above reactor may include a reaction mother liquor. Specifically, before supplying the reaction raw materials, which are an aqueous solution of a transition metal, an ammonium cation complex forming agent, and a basic compound, the ammonium cation complex forming agent, the basic compound, and water may be first introduced into the reactor to form a reaction mother liquor.

[0136] The ammonium cation complex forming agent may be at least one selected from the group consisting of NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3, and may be introduced into a reactor in the form of a solution in which the compound is dissolved in a solvent. At this time, the solvent may be water, or a mixture of water and an organic solvent (specifically, alcohol, etc.) that is uniformly miscible with water.

[0137] The above basic compound may be at least one selected from the group consisting of NaOH, KOH, and Ca(OH)2, and may be introduced into the reactor in the form of a solution in which the compound is dissolved in a solvent. In this case, water or a mixture of water and an organic solvent that is uniformly miscible with water (specifically, alcohol, etc.) may be used as the solvent.

[0138] The above reaction mother liquor can be formed such that its pH is 9.5 to 12.0, 10.0 to 11.8, or 10.0 to 11.5. When the pH of the reaction mother liquor satisfies the above range, nucleation can be carried out smoothly.

[0139] It is desirable to form a reaction mother liquor by introducing an ammonium cation complex forming agent, a basic compound, and water into a reactor, and then remove oxygen from the reaction mother liquor by purging with nitrogen gas.

[0140]

[0141] Next, an aqueous transition metal solution, an ammonium cation complex forming agent, and a basic compound are supplied to a reactor, and a co-precipitation reaction is carried out while stirring to prepare a reaction solution in which precursor seeds are formed.

[0142] When a transition metal aqueous solution, an ammonium cation complex forming agent, and a basic compound are supplied to a reactor containing a reaction mother liquor and stirred, a co-precipitation reaction proceeds, generating precursor nuclei in the form of primary particles, and as the primary particle nuclei aggregate, secondary particle nuclei (seeds) are formed.

[0143] In the nucleation step above, the transition metal aqueous solution may be supplied at a flow rate of 3.0 L / h to 6.0 L / h, 3.5 L / h to 5.7 L / h, 4.0 L / h to 5.5 L / h, or 4.5 L / h to 5.3 L / h. The above flow rate may be the average flow rate value during the co-precipitation reaction. If the above range is satisfied, nuclei having an appropriate density gradient can be formed.

[0144] In the above nucleation step, the ammonium cation complex forming agent may be supplied at a flow rate of 0.01 L / h to 5.0 L / h, 0.5 L / h to 4.5 L / h, 1.0 L / h to 4.5 L / h, or 2.0 L / h to 4.0 L / h. When the above range is satisfied, nuclei are formed smoothly, the growth rate of the nuclei can be maintained, and the degree of sphericity can be improved.

[0145] In the above nucleation step, the basic compound may be supplied at a flow rate of 0.5 L / h to 2.5 L / h, 1.0 L / h to 2.0 L / h, or 1.2 L / h to 1.8 L / h. If the above ranges are satisfied, the pH of the reaction solution can be maintained within an appropriate range.

[0146] The above transition metal aqueous solution may contain nickel, cobalt, and manganese elements, and may be formed by mixing nickel raw material, cobalt raw material, and manganese raw material in water.

[0147] The above nickel raw material may be Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, NiSO4, NiSO4·6H2O, nickel salts of fatty acids, or nickel halides, and any one or more of these may be used.

[0148] The above cobalt raw material may be Co(OH)2, CoOOH, Co(OCOCH3)2ㆍ4H2O, Co(NO3)2ㆍ6H2O, or Co(SO4)2ㆍ7H2O, etc., and any one or more of these may be used.

[0149] The above manganese raw materials may be manganese oxides such as Mn2O3, MnO2, and Mn3O4; manganese salts such as MnCO3, Mn(NO3)2, MnSO4, manganese acetate, manganese dicarboxylate, manganese citrate, and manganese fatty acid salts; oxyhydroxide, or manganese chloride, and any one or more of these may be used.

[0150] If necessary, the above transition metal aqueous solution may further include doping elements in addition to nickel, cobalt, and manganese. In this case, the doping element may include at least one selected from the group consisting of Mn, Al, Ba, Ca, Zr, Ti, Mg, Ta, Nb, and Mo. When the above positive active material further includes doping elements, the effect of improving lifespan characteristics, discharge characteristics, and / or stability can be achieved.

[0151] If the above transition metal aqueous solution further includes the above doping element, the raw material containing the above doping element may be optionally added during the preparation of the above transition metal aqueous solution.

[0152] As the raw material containing the doping element, at least one selected from the group consisting of acetates, sulfates, sulfides, hydroxides, oxides, or oxyhydroxides containing the doping element may be used.

[0153] The above ammonium cation complex forming agent and basic compound may be the same as the ammonium cation complex forming agent and basic compound used when forming the reaction mother liquor.

[0154]

[0155] The above nucleation step may be performed for 10 to 120 hours, 12 to 80 hours, 15 to 50 hours, 20 to 40 hours, 25 to 34 hours, or 27 to 32 hours. If the nucleation time is too short, sufficient nuclei are not generated, which may reduce productivity and result in a non-uniform particle size distribution of the precursor particles. Additionally, if the nucleation time is too long, the reaction time required to grow the precursor particles to the desired particle size may become too long, which may reduce productivity and result in a non-uniform particle size distribution as some particles grow during the nucleation process. Therefore, if the nucleation time satisfies the above range, the particle size distribution of the manufactured precursor for the cathode active material can be uniform, and the internal structure of the precursor for the cathode active material can be controlled, which can affect the particle strength of the precursor for the cathode active material.

[0156] In the above nucleation step, the pH of the reaction solution in which the precursor nucleus for the positive electrode active material is formed may be 10.0 to 13.0, 10.0 to 12.5, 10.5 to 12.3, or 11.0 to 12.0. In the above nucleation step, the temperature of the reaction solution may be 40°C to 70°C, 50°C to 68°C, or 55°C to 65°C.

[0157] When the pH and temperature of the reaction solution satisfy the above ranges, nuclei of cathode active material precursors are formed within the reaction solution, and the process in which these nuclei aggregate to form final nuclei can proceed smoothly. The pH of the reaction solution can be controlled by adjusting the amount of basic compound added using a pH sensor or the like.

[0158] The precursor nuclei for the positive electrode active material formed in the above nucleation step have an average particle size D 50This can be 1㎛ to 10㎛, 1.5㎛ to 8㎛, 2㎛ to 5㎛, 3㎛ to 4.4㎛, or 3.75㎛ to 3.85㎛. In this case, the average particle size of the precursor for a positive active material manufactured using the above-mentioned precursor nucleus for a positive active material is appropriate, and the particle strength can also be appropriately controlled.

[0159]

[0160] (2) Particle growth stage

[0161] When nuclei are sufficiently formed through the above process, precursor particles for the positive electrode active material are grown by co-precipitating a transition metal aqueous solution, an ammonium cation complex forming agent, and a basic compound while supplying them to the reaction solution in which the precursor nuclei for the positive electrode active material have been formed.

[0162] In the particle growth step, the transition metal aqueous solution is supplied at a first flow rate of 8 L / h to 11.5 L / h, and then supplied at a second flow rate of 20 L / h to 30 L / h. When the transition metal aqueous solution is supplied by changing the flow rate from the first to the second as described above, the internal structure of the particles can be formed porously, thereby allowing the particle strength of the precursor particles for the positive electrode active material to be controlled to satisfy a specific range. When a positive electrode active material is manufactured using such precursor particles for the positive electrode active material, a positive electrode active material with a particle strength satisfying a specific range can be manufactured. When the positive electrode active material is applied as a large-particle positive electrode active material to a bimodal structured positive electrode material, particle breakage of the positive electrode active material can be reduced during rolling.

[0163] The above first flow rate may be 8 L / h or more, 8.2 L / h or more, 8.4 L / h or more, 8.6 L / h or more, 8.8 L / h or more, 9 L / h or more, 9.2 L / h or more, 9.4 L / h or more, 9.6 L / h or more, 9.8 L / h or more, 10 L / h or more, 11.5 L / h or less, 11.4 L / h or less, 11.2 L / h or less, 11 L / h or less, 10.8 L / h or less, 10.6 L / h or less, 10.4 L / h or less, 10.2 L / h or less, or 10 L / h or less. For example, the first flow rate may be 8 to 11.5 L / h, 8.5 to 11.5 L / h, 9 to 11 L / h, or 9.5 to 10.5 L / h. When the above range is satisfied, the internal porosity of the precursor for the positive electrode active material can be improved, and the particle strength of the precursor for the positive electrode active material can be controlled to a desired range.

[0164] The above second flow rate may be 20 L / h or more, 20.5 L / h or more, 21 L / h or more, 21.5 L / h or more, 22 L / h or more, 22.5 L / h or more, 23 L / h or more, 23.5 L / h or more, 24 L / h or more, 24.5 L / h or more, 25 L / h or more, 30 L / h or less, 29.5 L / h or less, 29 L / h or less, 28.5 L / h or less, 28 L / h or less, 27.5 L / h or less, 27 L / h or less, 26.5 L / h or less, 26 L / h or less, 25.5 L / h or less, or 25 L / h or less. For example, the second flow rate may be 20 L / h to 30 L / h, 22 L / h to 28 L / h, 23 L / h to 27 L / h, or 24 L / h to 26 L / h. When the above range is satisfied, the degree of crystallization of the precursor for the positive active material is improved, thereby increasing the physical stability of the precursor for the positive active material, and accordingly, the particle strength of the precursor for the positive active material can be controlled.

[0165] The second flow rate may be 2 times or more, 2.1 times or more, 2.2 times or more, 2.3 times or more, 2.4 times or more, 2.5 times or more, 4.0 times or less, 3.8 times or less, 3.5 times or less, 3.2 times or less, 3 times or less, 2.9 times or less, 2.8 times or less, 2.7 times or less, 2.6 times or less, or 2.5 times or less of the first flow rate. When the above range is satisfied, depending on the difference between the first flow rate and the second flow rate, a structure can be formed in which the interior of the precursor has a high porosity and the surface has high physical stability, so that the manufactured cathode active material may have excellent crystallinity, excellent particle strength, and excellent lithium ion mobility.

[0166] In the particle growth step, the transition metal aqueous solution may be supplied at a first flow rate for 2 hours or less, 30 minutes to 90 minutes, or 40 minutes to 80 minutes. Afterwards, the transition metal aqueous solution may be supplied at a second flow rate for 7 hours to 13 hours, 8 hours to 12 hours, or 9 hours to 10 hours. If the above ranges are satisfied, the internal porosity of the precursor for the positive electrode active material can be improved, and the particle strength of the precursor for the positive electrode active material can be controlled to a desired range.

[0167] The supply flow rate of the ammonium cation complex forming agent is increased to more than twice, 2 to 10 times, or 2 to 9 times the supply flow rate in the nucleation step. When the supply rate of the ammonium cation complex forming agent is rapidly increased to more than twice during the particle growth step, the reaction rate increases due to the increase in reaction raw materials, and the surface density and primary particle size of the generated precursor particles decrease, thereby producing precursor particles with a large specific surface area. When such precursors with a large specific surface area are used in the manufacture of the cathode active material, the reactivity between the precursor and the lithium raw material is improved during the calcination step, thereby improving calcination uniformity and developing the crystal structure well.

[0168] The transition metal aqueous solution, ammonium cation complex forming agent, and basic compound introduced in the particle growth step are the same as those used in the nucleation step.

[0169]

[0170] In the particle growth step, before supplying the transition metal aqueous solution, ammonium cation complex forming agent, and basic compound to the reaction solution, the reaction solution may be purged with an inert gas, such as nitrogen (N2) gas, to remove dissolved oxygen and create a non-oxidizing atmosphere inside the reactor.

[0171] The above inert gas can be purged into the reactor at a rate of 100 to 500 L / h, 200 to 400 L / h, or 250 to 350 L / h. If the above range is satisfied, the crystallinity of the precursor for the cathode active material can be improved.

[0172] The pH of the reaction solution in which precursor particles for the cathode active material are grown during the particle growth step may be 10.5 to 12.5, 10.7 to 12.2, or 11.0 to 12.0. When the pH of the reaction solution satisfies the above range, the growth of the precursor particles can proceed smoothly. The pH of the reaction solution can be controlled by adjusting the amount of basic compound added using a pH sensor or the like.

[0173] In the particle growth step, the co-precipitation reaction may be performed at a temperature of 46°C or higher, 47°C or higher, 48°C or higher, 49°C or higher, 50°C or higher, 51°C or higher, 52°C or higher, 53°C or higher, less than 60°C, 59°C or lower, 58°C or lower, 57°C or lower, 56°C or lower, 55°C or lower, 54°C or lower, or 53°C or lower. For example, in the particle growth step, the co-precipitation reaction may be performed at a temperature of 46 to 59°C, 50 to 57°C, 51 to 55°C, or 52 to 54°C. When the temperature of the co-precipitation reaction satisfies the above range, transition metal ions are sufficiently dissolved while preventing the volatilization of the introduced solutions, thereby improving the crystallinity of the precursor particles for the cathode active material, and accordingly, precursor particles for the cathode active material having appropriate particle strength can be produced.

[0174] In the particle growth step above, the reaction for growing precursor particles for the positive electrode active material may be carried out for 7 to 100 hours, 8 to 90 hours, 9 to 87 hours, 30 to 85 hours, 50 to 84 hours, or 60 to 83 hours. If the above range is satisfied, precursor particles for the positive electrode active material can be obtained in which the particle strength is controlled to a desired range while growing the precursor particles for the positive electrode active material to an appropriate size.

[0175] When the reactor becomes full during the particle growth stage, the supply of raw materials is stopped and stirring is halted to allow the precursor particles in the reaction solution to settle, after which the supernatant is removed and the supply of raw materials is resumed to proceed with the reaction. By performing the process of removing the supernatant from the reactor as described above, sufficient reaction time required for precursor particle growth can be secured, and the production volume of the precursor can be increased. The above process may be repeated two or more times.

[0176] When the precursor particles grow sufficiently through the above process, the precursor particles can be separated from the reaction solution, washed, and dried to obtain precursor particles for the cathode active material.

[0177] Since the obtained precursor for the positive electrode active material is identical to the aforementioned precursor for the positive electrode active material, a detailed description is omitted.

[0178]

[0179] positive electrode active material

[0180] The positive electrode active material according to the present invention comprises a lithium nickel-based oxide.

[0181] The above lithium nickel-based oxide may contain nickel.

[0182] The above lithium nickel-based oxide may contain nickel in an amount of 80 mol% or more, 82 mol% or more, 85 mol% or more, 88 mol% or more, 90 mol% or more, 92 mol% or more, 95 mol% or more, 97 mol% or more, 99 mol% or less, or 98 mol% or less among the total metals excluding lithium. For example, the above lithium nickel-based oxide may contain nickel in an amount of 80 mol% or more, 85 mol% to 99 mol%, 90 mol% to 99 mol%, or 95 mol% to 98 mol% among the total metals excluding lithium. In this case, high capacity characteristics can be achieved.

[0183] The above lithium nickel-based oxide may further contain cobalt.

[0184] The above lithium nickel-based oxide may contain cobalt among the total metals excluding lithium in an amount of 0.1 mol% or more, 0.2 mol% or more, 0.3 mol% or more, 0.4 mol% or more, 0.5 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 8 mol% or less, 5 mol% or less, 1 mol% or less, 0.8 mol% or less, or 0.5 mol% or less. For example, the above lithium nickel-based oxide may contain cobalt among the total metals excluding lithium in an amount of 20 mol% or less, 10 mol% or less, 5 mol% or less, 1 mol% or less, or 0.1 mol% or more and 1 mol% or less. When the above range is satisfied, output characteristics can be secured.

[0185] The above lithium nickel-based oxide may further contain manganese.

[0186] The above lithium nickel-based oxide may contain manganese among the total metals excluding lithium in an amount of 0.1 mol% or more, 0.5 mol% or more, 1 mol% or more, 1.5 mol% or more, 2 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 8 mol% or less, 5 mol% or less, 3 mol% or less, or 2 mol% or less. For example, the above lithium nickel-based oxide may contain manganese among the total metals excluding lithium in an amount of 20 mol% or less, 15 mol% or less, 10 mol% or less, or 1 mol% or more and 5 mol% or less. If the above ranges are satisfied, structural stability can be secured.

[0187] The above lithium nickel-based oxide may further include aluminum.

[0188] The above lithium nickel-based oxide may contain aluminum among the total metals excluding lithium in an amount of 0.1 mol% or more, 0.5 mol% or more, 1 mol% or more, 1.5 mol% or more, 2 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 8 mol% or less, 5 mol% or less, 3 mol% or less, 2 mol% or less, or 1 mol% or less. For example, the above lithium nickel-based oxide may contain aluminum among the total metals excluding lithium in an amount of 20 mol% or less, 15 mol% or less, 10 mol% or less, or 0.1 mol% or more and 5 mol% or less. When the above ranges are satisfied, output characteristics and structural stability can be secured.

[0189] The lithium nickel-based oxide may further include a doping element. The doping element may be one or more selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, or one or more selected from the group consisting of W, Y, Ba, Ca, Ti, Mg, Ta, and Nb.

[0190] The lithium nickel-based oxide may contain the doping element in an amount of 0.1 mol% or more, 0.2 mol% or more, 0.3 mol% or more, 0.4 mol% or more, 0.5 mol% or more and 10 mol% or less, 8 mol% or less, 5 mol% or less, 1 mol% or less, 0.8 mol% or less, or 0.5 mol% or less among the total metals excluding lithium. For example, the lithium nickel-based oxide may contain the doping element in an amount of 10 mol% or less, 8 mol% or less, 5 mol% or less, or 1 mol% or less among the total metals excluding lithium. When the above ranges are satisfied, output characteristics and structural stability can be improved.

[0191] The above lithium nickel-based oxide can be represented by the following chemical formula 2.

[0192] [Chemical Formula 2]

[0193] Li1+a2 [Ni x2 Co y2 M 4 z2 M 5 w2 ]O2

[0194] In the above chemical formula 2, the M 4 It may be Mn, Al, or a combination thereof, or Mn or a combination of Mn and Al.

[0195] The above M 5 may correspond to a doping element that partially substitutes a transition metal element included in a lithium nickel-based oxide, and may be optionally included or not included. The above M 5 When included in lithium nickel-based oxides, it can inhibit the movement of nickel ions, thereby preventing the problem of nickel (Ni) valence changing from 2+ to 4+ and the problem of cation mixing. Specifically, the above M 5 may be one or more doping elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, or one or more doping elements selected from the group consisting of W, Y, Ba, Ca, Ti, Mg, Ta, and Nb.

[0196] The above 1+a2 may represent the molar ratio of lithium (Li) in the lithium nickel-based oxide, and may be 0≤a2≤0.5, 0≤a2≤0.2, 0≤a2≤0.1, or 0≤a2≤0.05. When the above range is satisfied, the positive electrode active material can form a stable layered crystal structure.

[0197] The above x2 may represent the molar ratio of nickel among the total metals excluding lithium in the lithium nickel-based oxide particles, and may be 0.8≤x2<1.0, 0.85≤x2≤0.99, 0.90≤x2≤0.99, or 0.95≤x2≤0.98. When the above range is satisfied, the capacity characteristics of the positive electrode active material may be excellent.

[0198] The above y2 may represent the molar ratio of cobalt among the total metals excluding lithium in the lithium nickel-based oxide particles, and 0 <y2≤0.2, 0<y2≤0.1, 0<y2≤0.05, 또는 0<y2≤0.01일 수 있다. 상기 범위를 만족하는 경우, 비용적인 이점을 가지면서, 출력 특성이 개선될 수 있다.

[0199] The above z2 is M among the total metals excluding lithium in the above lithium nickel-based oxide particles. 4 This can mean the mole ratio occupied, and 0 <z2≤0.2, 0<z2≤0.15, 0<z2≤0.1, 또는 0.01≤z2≤0.05일 수 있다. 상기 범위를 만족할 경우, 양극 활물질의 구조적 안정성을 향상시킬 수 있다.

[0200] The above w2 is M among the total metals excluding lithium in the above lithium nickel-based oxide. 5 It represents the molar ratio of the elements, which may be 0≤w2≤0.1, 0≤w2≤0.08, 0≤w2≤0.05, or 0≤w2≤0.01. When the above range is satisfied, it can play a role in promoting particle growth during the calcination of the positive active material or improving crystal structure stability.

[0201] Alternatively, the lithium nickel-based oxide may be represented by the following chemical formula 2-1.

[0202] [Chemical Formula 2-1]

[0203] Li 1+a3 [Ni x3 Co y3 Mn z3 M 6 w3 ]O2

[0204] In the above chemical formula 2-1, the M 6 may correspond to a doping element that partially substitutes a transition metal element included in a lithium nickel-based oxide, and may be optionally included or not included. The above M 6 When included in lithium nickel-based oxides, it can inhibit the movement of nickel ions, thereby preventing the problem of nickel (Ni) valence changing from 2+ to 4+ and the problem of cation mixing. Specifically, the above M 6 may be one or more doping elements selected from the group consisting of Al, W, Cu, Fe, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, or one or more doping elements selected from the group consisting of Al, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb.

[0205] The above 1+a3 may represent the molar ratio of lithium (Li) in the lithium nickel-based oxide, and may be 0≤a3≤0.5, 0≤a3≤0.2, 0≤a3≤0.1, or 0≤a3≤0.05. When the above range is satisfied, the positive electrode active material can form a stable layered crystal structure.

[0206] The above x3 may represent the molar ratio of nickel among the total metals excluding lithium in the lithium nickel-based oxide particles, and may be 0.8≤x3<1.0, 0.85≤x3≤0.99, 0.90≤x3≤0.99, or 0.95≤x3≤0.98. When the above range is satisfied, the capacity characteristics of the positive electrode active material may be excellent.

[0207] The above y3 may represent the molar ratio of cobalt among the total metals excluding lithium in the lithium nickel-based oxide particles, and 0 <y3≤0.2, 0<y3≤0.1, 0<y3≤0.05, 또는 0<y3≤0.01일 수 있다. 상기 범위를 만족하는 경우, 비용적인 이점을 가지면서, 출력 특성이 개선될 수 있다.

[0208] The above z3 may refer to the molar ratio of manganese among the total metals excluding lithium in the lithium nickel-based oxide particles, and 0 <z3≤0.2, 0<z3≤0.15, 0<z3≤0.1, 또는 0.01≤z3≤0.05일 수 있다. 상기 범위를 만족할 경우, 양극 활물질의 구조적 안정성이 개선될 수 있다.

[0209] The above w3 is M among the total metals excluding lithium in the above lithium nickel-based oxide. 6 It represents the molar ratio of the elements, which may be 0≤w3≤0.1, 0≤w3≤0.08, 0≤w3≤0.05, or 0≤w3≤0.01. When the above range is satisfied, it can play a role in promoting particle growth during the calcination of the cathode active material or improving crystal structure stability.

[0210]

[0211] The above positive active material may, if necessary, further include a coating layer comprising one or more coating elements selected from the group consisting of Al, B, Co, W, Ti, Mg, Zr, Y, Ba, Ca, Sr, Ta, Nb, and Mo on the surface of the lithium nickel-based oxide particles. Alternatively, the coating element may be Al, B, Co, or a combination thereof.

[0212] When a coating layer is present on the surface of the above lithium nickel-based oxide particles, contact between the electrolyte and the lithium nickel-based oxide is suppressed by the coating layer, thereby reducing the leaching of transition metals or gas generation caused by side reactions with the electrolyte.

[0213]

[0214] The above positive active material may have a particle strength of 260 MPa to 390 MPa.

[0215] Specifically, the anode active material may have a particle strength of 260 MPa or more, 265 MPa or more, 270 MPa or more, 275 MPa or more, 280 MPa or more, 285 MPa or more, 290 MPa or more, 295 MPa or more, 300 MPa or more, 305 MPa or more, 310 MPa or more, 315 MPa or more, 320 MPa or more, 325 MPa or more, and may be 390 MPa or less, 380 MPa or less, 370 MPa or less, 360 MPa or less, 350 MPa or less, 340 MPa or less, or 330 MPa or less. For example, the anode active material may have a particle strength of 260 MPa to 390 MPa, 280 MPa to 380 MPa, 300 MPa to 370 MPa, 310 MPa to 350 MPa, or 320 MPa to 340 MPa. The particle strength of the anode active material can be controlled by controlling the internal structure of the anode active material through the particle strength of the precursor for the anode active material, the calcination time, the calcination temperature, etc.

[0216] If the above-mentioned positive active material has a particle strength lower than the above range, the mechanical strength of the positive active material is low, and numerous particle breakage of the positive active material may occur during rolling. Alternatively, if the above-mentioned positive active material has a particle strength higher than the above range, problems may arise, such as difficulty in dispersing stress within the particles of the positive active material during charging and discharging, or a decrease in electrolyte impregnation.

[0217] Accordingly, the positive electrode active material according to the present invention satisfies the above range of particle strength, thereby minimizing particle breakage during rolling and simultaneously sufficiently dispersing stress within the positive electrode active material particles during charging and discharging. As a result, degradation of the positive electrode active material and an increase in gas generation due to side reactions in the electrolyte can be suppressed, thereby improving lifespan characteristics. Furthermore, the problem of reduced electrical conductivity caused by the loss of electron movement paths within the electrode due to particle breakage can be prevented, and resistance characteristics can be improved.

[0218] In particular, when the above-mentioned cathode active material is applied as a large-particle cathode active material in a bimodal structured cathode material, it is possible to improve energy density while reducing particle breakage during rolling, thereby enabling excellent capacity and lifespan characteristics.

[0219]

[0220] The above positive active material has an average particle size (D 50 ) may be 5㎛ or more, 5.5㎛ or more, 6㎛ or more, 6.5㎛ or more, 7㎛ or more, 7.5㎛ or more, 8㎛ or more, 8.5㎛ or more, 9㎛ or more, 9.5㎛ or more, 10㎛ or more, 10.5㎛ or more, 11㎛ or more, 18㎛ or less, 17.5㎛ or less, 17㎛ or less, 16.5㎛ or less, 16㎛ or less, 15.5㎛ or less, 15㎛ or less, 14.5㎛ or less, 14㎛ or less, 13.5㎛ or less, 13㎛ or less, 12.5㎛ or less, 12㎛ or less, or 11.5㎛ or less. For example, the above-mentioned cathode active material may have an average particle size (D 50 The thickness may be 5㎛ to 18㎛, 7㎛ to 16㎛, 8㎛ to 14㎛, or 10㎛ to 12㎛. When the above range is satisfied, the rolling density can be increased when applied to the anode, and accordingly, the electrode density is improved, thereby enabling the realization of excellent energy density. This effect can be maximized when the anode active material is applied as a large-particle anode active material in a bimodal structured anode material.

[0221] The above positive active material may have a SPAN value defined by the following formula C of 0.2 to 0.7, 0.3 to 0.6, or 0.3 to 0.4. When the above range is satisfied, the particle size of the above positive active material may be uniform.

[0222] [Equation C]

[0223] SPAN = (D 90 -D 10 ) / D 50

[0224] In the above equation C, D 90, D 50, D 10 These are the particle size values ​​when the cumulative volume is 90%, 50%, and 10%, respectively, in the volume-based particle size distribution of the above-mentioned positive active material.

[0225] The above positive active material may include secondary particles. In this case, it may have the effect of having excellent resistance, charge / discharge efficiency, and capacity characteristics.

[0226]

[0227] The above-mentioned positive electrode active material may comprise a calcined mixture of the aforementioned precursor for the positive electrode active material and a lithium raw material. That is, the above-mentioned positive electrode active material may be manufactured by mixing the aforementioned precursor for the positive electrode active material and a lithium raw material and calcining them.

[0228] Except for using precursor particles for the positive electrode active material obtained as described above, the calcined body of the mixture of the positive electrode active material precursor and the lithium raw material may be obtained by a calcination method known in the relevant technical field, and the method is not particularly limited.

[0229] The above lithium raw materials may include lithium-containing carbonates (e.g., lithium carbonate, etc.), hydrates (e.g., lithium hydroxide hydrate (LiOH·H2O), etc.), hydroxides (e.g., lithium hydroxide, etc.), nitrates (e.g., lithium nitrate (LiNO3), etc.), chlorides (e.g., lithium chloride (LiCl), etc.), and one of these alone or a mixture of two or more may be used.

[0230] The mixing of the precursor particles for the positive electrode active material and the lithium raw material can be carried out by solid-state mixing such as jet milling. The mixing ratio of the precursor particles for the positive electrode active material 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 finally manufactured. More specifically, the precursor particles for the positive electrode active material and the lithium raw material may be mixed such that the lithium element in the precursor particles for the positive electrode active material and the lithium raw material is in a molar ratio of 1:1.0 to 1:1.5 or 1:1.0 to 1:1.3.

[0231] Although not essential, in addition to the precursor for the cathode active material and the lithium raw material, raw materials for doping some of the transition metals and / or oxygen of the cathode active material may be additionally included in the above mixture. For example, the raw material containing the doping element described above may be additionally mixed in the above mixture.

[0232]

[0233] The above firing may be performed at a temperature of 600°C to 800°C, 620°C to 750°C, or 650°C to 720°C, but is not limited thereto.

[0234] The above firing may be performed for 5 to 20 hours, 7 to 15 hours, or 8 to 10 hours, but is not limited thereto.

[0235]

[0236] cathode material

[0237] The cathode material according to the present invention comprises a first cathode active material; and a second cathode active material. The first cathode active material is the aforementioned cathode active material.

[0238]

[0239] The above-mentioned cathode material is a cathode material having a bimodal structure, wherein the first cathode active material and the second cathode active material have an average particle size (D 50 ) differs. Specifically, the first positive electrode active material has an average particle size (D) greater than that of the second positive electrode active material. 50 ) is large. Accordingly, when rolling the electrode, the second positive active material with small particle size is filled into the pores of the first positive active material with large particle size, increasing the electrode density and enabling high energy density to be achieved, thereby enabling high capacity characteristics.

[0240]

[0241] Hereinafter, each component of the cathode material according to the present invention will be described in detail.

[0242]

[0243] (1) First positive active material

[0244] The first positive active material is identical to the aforementioned positive active material. That is, the positive active material according to the present invention is applied as a first positive active material having a relatively large average particle size in the positive material. If the positive active material according to the present invention is applied as a second positive active material having a relatively small average particle size in the positive material, it is not possible to prevent pressure concentration during rolling on the first positive active material; therefore, problems such as particle breakage occurring in the first positive active material, resulting in degradation of the positive active material and gas generation, cannot be resolved. Accordingly, by applying the positive active material according to the present invention as a first positive active material having a relatively large average particle size, particle breakage during rolling can be reduced, and energy density, lifespan characteristics, and resistance characteristics can be improved.

[0245] The above-mentioned first positive active material is identical to the aforementioned positive active material, so a detailed description is omitted.

[0246]

[0247] (2) Second positive active material

[0248] The above second positive active material corresponds to a positive active material with a relatively small particle size among the above positive materials.

[0249] The above-mentioned second positive active material may include single-particle type particles. In this case, compared to conventional positive active materials in the form of secondary particles where tens to hundreds of primary particles are aggregated, particle breakage during rolling is almost non-existent because the particle strength is higher. Furthermore, when single-particle type particles are included, the number of nodules constituting the particles is small, so there is less change due to volume expansion and contraction of the nodules during charging and discharging, and consequently, the occurrence of cracks inside the particles can be significantly reduced. In addition, since the contact area between the electrolyte and the positive active material is small, gas generation due to side reactions of the electrolyte is reduced and thermal stability can be excellent. Accordingly, it can have the effect of slowing down the degradation of the positive active material and improving lifespan characteristics.

[0250] Meanwhile, in order to solve the problem of increased particle breakage caused by force concentration on the first cathode active material during rolling, as the second cathode active material includes single-particle type particles and thus improves particle strength, the cathode material according to the present invention applies the aforementioned cathode active material as the first cathode active material. Specifically, even if the first cathode active material and the second cathode active material including single-particle type particles are mixed, the particle strength of the first cathode active material is controlled to a specific range such that the first cathode active material can withstand the force concentrated on it during rolling. Consequently, particle breakage is minimized, and internal stress within the particles can also be dispersed, thereby preventing the occurrence of particle cracks. Accordingly, the cathode material according to the present invention can achieve effects such as improved lifespan characteristics, reduced gas generation, and improved resistance characteristics while maintaining the effect of improved energy density resulting from the application of a bimodal structured cathode material.

[0251]

[0252] The above second positive active material may include a lithium nickel-based oxide.

[0253] The above lithium nickel-based oxide may contain nickel in an amount of 80 mol% or more, 82 mol% or more, 85 mol% or more, 88 mol% or more, 90 mol% or more, 92 mol% or more, 94 mol% or more, 99 mol% or less, 98 mol% or less, 97 mol% or less, 96 mol% or less, or 95 mol% or less among the total metals excluding lithium. For example, the above lithium nickel-based oxide may contain nickel in an amount of 80 mol% or more, 85 mol% to 99 mol%, 90 mol% to 99 mol%, or 92 mol% to 98 mol% among the total metals excluding lithium. In this case, high capacity characteristics can be achieved.

[0254] The above lithium nickel-based oxide may further contain cobalt.

[0255] The above lithium nickel-based oxide may contain cobalt among the total metals excluding lithium in an amount of 0.1 mol% or more, 0.3 mol% or more, 0.5 mol% or more, 0.8 mol% or more, 1 mol% or more, 1.5 mol% or more, 2 mol% or more, 2.5 mol% or more, 3 mol% or more, 3.5 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 8 mol% or less, 5 mol% or less, 4 mol% or less, or 3.5 mol% or less. For example, the above lithium nickel-based oxide may contain cobalt among the total metals excluding lithium in an amount of 20 mol% or less, 10 mol% or less, 0.1 mol% or more and 8 mol% or less, 1 mol% or more and 5 mol% or more, or 3 mol% or more and 4 mol% or less. When the above ranges are satisfied, output characteristics can be secured.

[0256] The above lithium nickel-based oxide may further contain manganese.

[0257] The above lithium nickel-based oxide may contain manganese among the total metals excluding lithium in an amount of 0.1 mol% or more, 0.5 mol% or more, 1 mol% or more, 1.5 mol% or more, 2 mol% or more, 2.5 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 8 mol% or less, 5 mol% or less, 3 mol% or less, or 2.5 mol% or less. For example, the above lithium nickel-based oxide may contain manganese among the total metals excluding lithium in an amount of 20 mol% or less, 15 mol% or less, 10 mol% or less, 0.1 mol% or more and 8 mol% or less, 1 mol% or more and 5 mol%, or 2 mol% or more and 3 mol% or less. Structural stability can be secured when the above ranges are satisfied.

[0258] The above lithium nickel-based oxide may further include aluminum.

[0259] The above lithium nickel-based oxide may contain aluminum among the total metals excluding lithium in an amount of 0.1 mol% or more, 0.5 mol% or more, 1 mol% or more, 1.5 mol% or more, 2 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 8 mol% or less, 5 mol% or less, 3 mol% or less, 2 mol% or less, or 1 mol% or less. For example, the above lithium nickel-based oxide may contain aluminum among the total metals excluding lithium in an amount of 20 mol% or less, 15 mol% or less, 10 mol% or less, or 1 mol% or less. When the above ranges are satisfied, output characteristics and structural stability can be secured.

[0260] The lithium nickel-based oxide may further include a doping element. The doping element may be one or more selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, or one or more selected from the group consisting of W, Y, Ba, Ca, Ti, Mg, Ta, and Nb.

[0261] The lithium nickel-based oxide may contain the doping element in an amount of 0.1 mol% or more, 0.2 mol% or more, 0.3 mol% or more, 0.4 mol% or more, 0.5 mol% or more and 10 mol% or less, 8 mol% or less, 5 mol% or less, 1 mol% or less, 0.8 mol% or less, or 0.5 mol% or less among the total metals excluding lithium. For example, the lithium nickel-based oxide may contain the doping element in an amount of 10 mol% or less, 8 mol% or less, 5 mol% or less, or 1 mol% or less among the total metals excluding lithium. When the above ranges are satisfied, output characteristics and structural stability can be improved.

[0262] The above second positive active material may include a lithium nickel-based oxide represented by the following chemical formula 3.

[0263] [Chemical Formula 3]

[0264] Li 1+a4 [Ni x4 Co y4 M 7 z4 M 8 w4 ]O2

[0265] In the above chemical formula 3, the M 7 It is Mn, Al, or a combination thereof, and preferably may be Mn or a combination of Mn and Al.

[0266] The above M 8 may correspond to a doping element that partially substitutes a transition metal element contained in a lithium nickel-based oxide, and can play a role in preventing the problem of nickel (Ni) valence changing from 2+ to 4+ and the problem of cation mixing by inhibiting the movement of nickel ions. Specifically, the above M 8 may be one or more doping elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, or one or more doping elements selected from the group consisting of W, Y, Ba, Ca, Ti, Mg, Ta, and Nb.

[0267] The above 1+a4 may represent the molar ratio of lithium (Li) in the lithium nickel-based oxide, and may be 0.5≤1+a4≤1.5, 0.8≤1+a4≤1.2, or 0.9≤1+a4≤1.1. When the above range is satisfied, the positive electrode active material can form a stable layered crystal structure.

[0268] The above x4 may represent the molar ratio of nickel among the total metals excluding lithium in the lithium nickel-based oxide particles, and may be 0.8≤x4<1, 0.85≤x4≤0.99, 0.90≤x4≤0.99, or 0.92≤x4≤0.98. When the above range is satisfied, the capacity characteristics may be excellent.

[0269] The above y4 may represent the molar ratio of cobalt among the total metals excluding lithium in the lithium nickel-based oxide particles, and 0 <y4≤0.2, 0<y4≤0.1, 0.001≤y4≤0.08, 0.01≤y4≤0.05, 또는 0.03≤y4≤0.04일 수 있다. 상기 범위를 만족하는 경우, Co 함량을 낮춤으로써 비용적인 이점을 가지며, 양호한 저항 특성 및 출력 특성을 구현할 수 있다.

[0270] The above z4 is M among the total metals excluding lithium in the above lithium nickel-based oxide particles. 7 This can mean the mole ratio occupied, and 0 <z4≤0.2, 0<z4≤0.1, 0.001≤z4≤0.08, 0.01≤z4≤0.05, 또는 0.02≤z4≤0.03일 수 있다. 상기 범위를 만족할 경우, 양극 활물질의 구조적 안정성을 향상시킬 수 있다.

[0271] The above w4 is M among the total metals excluding lithium in the above lithium nickel-based oxide. 8 It represents the molar ratio of the elements, which may be 0≤w4≤0.2, 0≤w4≤0.15, 0≤w4≤0.1, or 0≤w4≤0.01. When the above range is satisfied, it can play a role in promoting particle growth during the calcination of the positive active material or improving crystal structure stability.

[0272] Specifically, the positive electrode active material may include a lithium nickel-based oxide represented by the following chemical formula 3-1.

[0273] [Chemical Formula 3-1]

[0274] Li 1+a5 [Ni x5 Co y5 Mn z3 M 9 w5 ]O2

[0275] In the above chemical formula 3-1, the M 9may correspond to a doping element that partially substitutes a transition metal element included in lithium nickel-based oxides, and can play a role in improving structural stability by inhibiting the movement of nickel ions, thereby preventing the problem of nickel (Ni) valence changing from 2+ to 4+ and the problem of cation mixing. Specifically, the above M 9 may be one or more doping elements selected from the group consisting of Al, W, Cu, Fe, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, or one or more doping elements selected from the group consisting of Al, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb.

[0276] The above 1+a5 may represent the molar ratio of lithium (Li) in the lithium nickel-based oxide, and may be 0.5≤1+a5≤1.5, 0.8≤1+a5≤1.2, or 0.9≤1+a5≤1.1. When the above range is satisfied, the positive electrode active material can form a stable layered crystal structure.

[0277] The above x5 may represent the molar ratio of nickel among the total metals excluding lithium in the lithium nickel-based oxide particles, and may be 0.8≤x5<1, 0.85≤x5≤0.99, 0.90≤x5≤0.99, or 0.92≤x5≤0.98. When the above range is satisfied, the capacity characteristics may be excellent.

[0278] The above y5 may represent the molar ratio of cobalt among the total metals excluding lithium in the lithium nickel-based oxide particles, and 0 <y5≤0.2, 0<y5≤0.1, 0.001≤y5≤0.08, 0.01≤y5≤0.05, 또는 0.03≤y5≤0.04일 수 있다. 상기 범위를 만족하는 경우, Co 함량을 낮춤으로써 비용적인 이점을 가지며, 양호한 저항 특성 및 출력 특성을 구현할 수 있다.

[0279] The above z5 may refer to the molar ratio of manganese among the total metals excluding lithium in the lithium nickel-based oxide particles, and 0 <z5≤0.2, 0<z5≤0.1, 0.001≤z5≤0.08, 0.01≤z5≤0.05, 또는 0.02≤z5≤0.03일 수 있다. 상기 범위를 만족할 경우, 양극 활물질의 구조적 안정성을 향상시킬 수 있다.

[0280] The above w5 is M among the total metals excluding lithium in the above lithium nickel-based oxide. 6 It represents the molar ratio of the elements, which may be 0≤w5≤0.2, 0≤w5≤0.15, 0≤w5≤0.1, or 0≤w5≤0.01. When the above range is satisfied, it can play a role in promoting particle growth during the calcination of the positive active material or improving crystal structure stability.

[0281] The second positive electrode active material may, if necessary, further include a coating layer comprising one or more coating elements selected from the group consisting of Al, B, Co, W, Ti, Mg, Zr, Y, Ba, Ca, Sr, Ta, Nb, and Mo on the surface of the lithium nickel-based oxide particles. Preferably, the coating element may be Al, B, Co, or a combination thereof.

[0282] When a coating layer is present on the surface of the above lithium nickel-based oxide particles, contact between the electrolyte and the lithium nickel-based oxide is suppressed by the coating layer, thereby reducing the leaching of transition metals or gas generation caused by side reactions with the electrolyte.

[0283]

[0284] The second positive active material may have a particle strength of 600 MPa to 900 MPa, 650 MPa to 850 MPa, 680 MPa to 820 MPa, 700 MPa to 800 MPa, or 720 MPa to 780 MPa. When the above range is satisfied, it has sufficient particle strength so that particle breakage can be minimized even when the small particle size positive active material is rolled.

[0285]

[0286] The above second positive active material may have a ratio of particles with a particle size of 1 μm or less of 3.0 volume% or less, 2.5 volume% or less, or 2.0 volume% or less. If the above range is satisfied, particle breakage occurring in the second positive active material during rolling can be minimized.

[0287] The above second positive active material has an average particle size (D 50 ) may be 1㎛ or more, 1.2㎛ or more, 1.5㎛ or more, 1.7㎛ or more, 2㎛ or more, 2.2㎛ or more, 2.5㎛ or more, 2.7㎛ or more, 3㎛ or more, 3.5㎛ or more, 3.9㎛ or more, 5㎛ or less, 4.7㎛ or less, 4.5㎛ or less, 4.2㎛ or less, 4㎛ or less, or 3.9㎛ or less. For example, the above second cathode active material has an average particle size (D 50 ) may be 1㎛ to 5㎛, 2㎛ to 5㎛, or 3㎛ to 4.5㎛. When the above range is satisfied, the rolling density can be increased when applied to the anode, and accordingly, the electrode density is improved, thereby enabling excellent energy density.

[0288] The second positive active material may have a span value defined by the following formula C-1 of 0.2 to 1.3, 0.5 to 1.0, or 0.6 to 0.8. When the above range is satisfied, the particle size of the second positive active material may be uniform.

[0289] [Equation C]

[0290] SPAN = (D 90 -D 10) / D 50

[0291] In the above equation C, D 90, D 50, D 10 These are the particle size values ​​when the cumulative volume is 90%, 50%, and 10%, respectively, in the volume-based particle size distribution of the above-mentioned positive active material.

[0292]

[0293] The first positive active material and the second positive active material may be included in a weight ratio of 2:8 to 8:2, 3:7 to 7:3, or 4:6 to 6:4. When the above range is satisfied, excellent thermal stability of the manufactured battery can be secured while preventing degradation of output characteristics, maintaining contact between positive active material particles, and minimizing particle breakage.

[0294]

[0295] anode

[0296] The anode according to the present invention comprises the aforementioned anode material. Specifically, the anode may comprise an anode active material layer comprising the aforementioned anode material, and more specifically, may comprise an anode current collector; and an anode active material layer comprising the aforementioned anode material located on the anode current collector.

[0297]

[0298] Hereinafter, each component of the anode according to the present invention will be described in detail.

[0299]

[0300] (1) Positive current collector

[0301] Various positive current collectors used in the relevant technical field may be used as the positive current collector. For example, the positive current collector may be stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. The positive current collector may typically have a thickness of 3 to 500 μm, and fine irregularities may be formed on the surface of the positive current collector to increase the adhesion of the positive active material. The positive current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0302]

[0303] (2) Positive active material layer

[0304] The positive active material layer may be located on the positive current collector, and specifically, may be located on one or both sides of the positive current collector. The positive active material layer may be a single layer or a multilayer structure of two or more layers.

[0305] The above positive active material layer may include a positive material, a positive conductive material, and a positive binder.

[0306] The above-described cathode material comprises the cathode material according to the present invention described above, i.e., a first cathode active material; and a second cathode active material; wherein the first cathode active material has an average particle size (D) greater than that of the second cathode active material. 50 ) is large, and the first positive active material is the positive active material described above. The specific characteristics of the positive material are the same as those described above.

[0307]

[0308] The above-mentioned cathode material may be included in an amount of 90% to 99% by weight, preferably 92% to 98% by weight, and more preferably 94% to 98% by weight, based on the total weight of the cathode active material layer. If the above range is satisfied, the energy density and capacity characteristics of the lithium secondary battery to which the cathode is applied can be improved.

[0309] The above-mentioned positive electrode conductive material is used to impart conductivity to the electrode, and in the battery being constructed, it may be used without special limitations as long as it possesses electronic conductivity without causing chemical changes. 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, carbon fiber, carbon nanotube; metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used. The above-mentioned positive electrode conductive material may typically be included in an amount of 0.1 to 10 weight%, preferably 0.1 to 8 weight%, and more preferably 0.1 to 5 weight% based on the total weight of the positive electrode active material layer.

[0310] The above-mentioned anode binder serves to improve adhesion between anode material particles and adhesion between the anode material and the anode current collector. Specific examples include fluoropolymer-based binders comprising polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber-based binders comprising styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, or styrene-isoprene rubber; cellulose-based binders comprising carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, or regenerated cellulose; polyalcohol-based binders comprising polyvinyl alcohol; polyolefin-based binders comprising polyethylene or polypropylene; polyimide-based binders; and polyester-based binders. Examples include silane-based binders, and one of these alone or a mixture of two or more may be used. The anode binder may be included in an amount of 0.1 to 10 weight%, preferably 0.5 to 10 weight%, and more preferably 1 to 8 weight% based on the total weight of the anode active material layer.

[0311]

[0312] The anode may be manufactured by methods known in the art. For example, the anode may be manufactured by mixing an anode material, an anode binder, and an anode conductive material in a solvent to prepare an anode slurry, applying the anode slurry onto an anode current collector, and then drying and rolling, or by casting the anode slurry onto a separate support and then laminating the film obtained by peeling it off from the support onto an anode current collector. In this case, the solvent for the anode slurry may be any anode slurry solvents generally used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, or a mixture thereof, but is not limited thereto. The solvent may be used in an amount that dissolves or disperses the anode material, the anode conductive material, and the anode binder, and has a viscosity such that the anode slurry can be uniformly coated.

[0313]

[0314] lithium secondary battery

[0315] A lithium secondary battery according to the present invention is described. The lithium secondary battery according to the present invention comprises a positive electrode according to the present invention; a negative electrode disposed opposite to the positive electrode; and an electrolyte. Optionally, the lithium secondary battery according to the present invention may further comprise a separator interposed between the positive electrode and the negative electrode.

[0316] Since the anode above is the same as described above, the remaining components excluding the anode will be described below.

[0317]

[0318] (1) Cathode

[0319] In a lithium secondary battery according to the present invention, the negative electrode comprises a negative electrode active material layer including a negative electrode active material, and specifically, may include a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.

[0320]

[0321] The above-mentioned negative 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., and aluminum-cadmium alloy may be used. In addition, the above-mentioned negative current collector may typically have a thickness of 3 to 500 μm, and, similar to the positive current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding strength of the negative active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0322]

[0323] The above negative electrode active material layer may be located on the negative electrode current collector, and specifically, may be located on one or both sides of the negative electrode current collector. The above negative electrode active material layer may have a single-layer structure or a multi-layer structure of two or more layers.

[0324] When the negative electrode active material layer is a multilayer structure composed of two or more layers, the types and / or contents of the negative electrode active material, negative electrode binder, and / or negative electrode conductive material in each layer may differ from one another. By forming the negative electrode active material layer into a multilayer structure and varying the composition of each layer, the performance characteristics of the battery, such as rapid charging performance and output characteristics, can be appropriately controlled.

[0325] As the above-mentioned 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 alloys, Sn alloys, or Al alloys; and SiO₂ β Examples include metal oxides capable of doping and dedoping lithium, such as (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the metal compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more of these may be used.

[0326] The above carbonaceous materials may include both low-crystallinity carbon and high-crystallinity carbon. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, 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.

[0327] Preferably, the cathode active material may be a carbon-based cathode active material, wherein the carbon-based cathode active material may include, for example, natural graphite, artificial graphite, graphitized carbon fiber, amorphous carbon, soft carbon, hard carbon, or a combination thereof. More preferably, the carbon-based cathode active material may include natural graphite and artificial graphite.

[0328] The above carbon-based negative electrode active material has an average particle size D 50 This can be 2㎛ to 30㎛, preferably 5㎛ to 30㎛.

[0329] The above-mentioned negative electrode active material may be included in an amount of 80% to 98% by weight, preferably 90% to 98% by weight, and more preferably 93% to 98% by weight, based on the total weight of the negative electrode active material layer. When the content of the negative electrode active material satisfies the above range, excellent energy density can be achieved.

[0330]

[0331] The above-mentioned cathode active material layer may further include a cathode conductive material and / or a cathode binder together with the cathode active material.

[0332] The cathode conductive material is used to impart conductivity to the cathode, and in the battery being constructed, it can be used without special restrictions as long as it has electronic conductivity without causing chemical changes. Specific examples include carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, carbon nanotube; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more of them may be used.

[0333] The above-mentioned cathode conductive material may typically be included in an amount of 0.1 to 10 weight%, preferably 0.1 to 8 weight%, and more preferably 0.1 to 5 weight% based on the total weight of the cathode active material layer.

[0334] The above-mentioned cathode binder serves to improve adhesion between cathode active material particles and adhesion between the cathode active material and the cathode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used.

[0335] The above-mentioned cathode binder may be included in an amount of 0.1 to 10 weight%, preferably 0.5 to 10 weight%, and more preferably 1 to 8 weight% based on the total weight of the cathode active material layer.

[0336]

[0337] The above cathode may be manufactured by methods known in the art. For example, the cathode may be manufactured by mixing a cathode active material, a cathode binder, and / or a cathode conductive material in a solvent to prepare a cathode slurry, applying the cathode slurry onto a cathode current collector, and then drying and rolling, or by casting the cathode slurry onto a separate support and then laminating the film obtained by peeling it off from the support onto a cathode current collector.

[0338] Meanwhile, solvents commonly used in the relevant technical field may be used as the solvent for the cathode slurry, for example, dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, or mixtures thereof, but are not limited thereto. The solvent may be used in an amount that dissolves or disperses the cathode active material, cathode conductive material, and cathode binder, and has a viscosity such that the cathode slurry can be uniformly coated.

[0339]

[0340] (2) Electrolyte

[0341] The electrolyte according to the present invention may include a lithium salt and an organic solvent.

[0342] The above lithium salt can be used without special limitations as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably used within the range of 0.1 to 5.0 M, more preferably 0.1 to 3.0 M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and allow lithium ions to move effectively.

[0343]

[0344] The above organic solvent may include at least one of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

[0345] The above-mentioned cyclic carbonate-based organic solvent is a high-viscosity organic solvent and may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate.

[0346] In addition, the above-mentioned linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and as a representative example, at least one organic solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate may be used, and specifically, it may include ethylmethyl carbonate (EMC).

[0347] Specific examples of the above linear ester-based organic solvent may include at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0348] The above-mentioned cyclic ester-based organic solvent may include at least one organic solvent selected from the group consisting of butyrolactone, valerolactone, and caprolactone.

[0349] Preferably, the electrolyte according to the present invention may include ethylene carbonate and dimethyl carbonate as organic solvents.

[0350]

[0351] Meanwhile, in addition to the electrolyte components, the above electrolyte may additionally include other additives for the purpose of improving the lifespan characteristics of the battery, suppressing the reduction of battery capacity, and improving the discharge capacity of the battery.

[0352] These other additives may include at least one other additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sulfone compounds, sulfate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds different from the lithium salt contained in the electrolyte, as representative examples.

[0353] The above other additives are vinylene carbonate (VC), vinylethylene carbonate, fluoroethylene carbonate (FEC), 1,3-propane sulfone (PS), 1,4-butane sulfone, ethene sulfone, 1,3-propene sulfone (PRS), 1,4-butene sulfone, 1-methyl-1,3-propene sulfone, ethylene sulfate (ESA), trimethylene sulfate (TMS), methyl trimethylene sulfate (MTMS), tetraphenyl borate, lithium oxalyl difluoroborate, succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, Examples include one or more compounds selected from the group consisting of 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile, fluorobenzene, triethanolamine, ethylenediamine, tetravinylsilane, LiN(SO2F)2 (Lithium bis(fluorosulfonyl)imide, LiFSI), LiN(SO2CF3)2 (lithium bis(trifluoromethane sulfonyl)imide, LiTFSI), LiPO2F2, LiODFB, LiBOB (lithium bis-oxalate toborate (LiB(C2O4)2)) and LiBF4.

[0354] The above other additives may be included in an amount of 0.01 to 20 weight% based on the total weight of the electrolyte, and preferably in an amount of 0.05 to 5.0 weight%. If the content of the above other additives is less than 0.01 weight%, the effect of improving low-temperature output, high-temperature storage characteristics, and high-temperature life characteristics of the battery is negligible, and if the content of the above other additives exceeds 20 weight%, there is a possibility that excessive side reactions may occur within the electrolyte during charging and discharging of the battery. In particular, when the above SEI film-forming additives are added in excess, they may not decompose sufficiently at high temperatures and may remain as unreacted substances or precipitated within the electrolyte at room temperature. Accordingly, side reactions that degrade the lifespan or resistance characteristics of the secondary battery may occur.

[0355]

[0356] (3) Separator

[0357] The above separator physically separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions; any separator typically used in lithium secondary batteries can be used without any special restrictions. In this case, the separator may be interposed between the positive electrode and the negative electrode.

[0358] As the above separator, a porous polymer film made of a polyolefin-based polymer, such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, 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, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0359]

[0360] The lithium secondary battery according to the present invention as described above can be usefully applied to portable devices such as mobile phones, laptop computers, and digital cameras, as well as electric vehicles such as hybrid electric vehicles (HEVs). Since the lithium secondary battery according to the present invention exhibits excellent thermal stability and can achieve excellent capacity characteristics, it can be particularly usefully applied in the field of electric vehicles.

[0361] According to another embodiment of the present invention, a battery module comprising a lithium secondary battery according to the present invention as a unit cell and a battery pack comprising the same are provided.

[0362] The above battery module or battery pack can be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0363]

[0364] The present invention will be explained in more detail below through specific embodiments. However, the following embodiments are intended only to enable a person skilled in the art to fully understand and easily implement the present invention, and the scope of the present invention is not limited to the following embodiments.

[0365]

[0366] Examples and Comparative Examples

[0367] Example 1

[0368] <Manufacture of Precursors for Positive Active Materials>

[0369] (1) Nucleation stage

[0370] A transition metal aqueous solution with a concentration of 2.28 M was prepared by dissolving NiSO4, CoSO4, and MnSO4 in ion-exchanged water in amounts such that the molar ratio of nickel:cobalt:manganese was 97.5:0.5:2.0. A 20 L batch reactor was filled with distilled water, a 20 wt% concentration of ammonia water, and a 30 wt% concentration of sodium hydroxide aqueous solution, and the reactor temperature was increased while purging with N2 gas and stirring at 500 rpm.

[0371] When the internal solution temperature of the reactor reaches 60℃, the transition metal aqueous solution is quantitatively injected at a rate of 5 L / h, and ammonia solution with a concentration of 20 wt% is injected at a rate of 3.0 L / h; additionally, an aqueous sodium hydroxide solution is injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5. In the nucleation step, the reaction [causes] the average particle size D of the prepared nuclei 50 This was performed for about 30 hours until it became about 3.8㎛.

[0372] (2) Particle growth stage

[0373] After 1 hour, N2 gas was purged into the reaction solution at a rate of 300 L / h, then the transition metal aqueous solution was supplied at a supply rate of 10 L / h (first flow rate) for 1 hour, and then supplied at a supply rate of 25 L / h (second flow rate) for 9 hours.

[0374] At the same time, the ammonia solution was supplied at a rate of 25 L / h for 10 hours, and then a sodium hydroxide solution was injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5 and the reaction solution temperature at 53℃ while carrying out the co-precipitation reaction.

[0375] When the volume of the reaction solution reached 20 L, the supply of reactants was stopped, stirring was halted to allow the precursor intermediate to settle, the supernatant was removed, and the reaction was resumed. This process was repeated about 5 times, and the reaction was terminated when the average particle size D50 of the precursor particles reached 12 µm. The total reaction time was 80 hours.

[0376] After separating the precursor particles from the reaction solution, impurities were removed by washing, and the precursor for the cathode active material was prepared by drying in a 130°C drying oven for 10 hours and then sieving.

[0377] <Manufacturing of Cathode Active Material>

[0378] The above-prepared precursor for the cathode active material and LiOH were mixed such that the molar ratio of (Ni+Co+Mn) : Li was 1 : 1.05, and then calcined at 680°C for 10 hours to prepare the cathode active material. The prepared cathode active material is LiNi 0.975 Co 0.005 Mn 0.02 It has a composition of O2, with an average particle size D 50 It was confirmed that this is 11.2 μm and has the form of a secondary particle.

[0379]

[0380] Comparative Example 1

[0381] <Preparation of precursor for positive active material>(1) Nucleation stage

[0382] A transition metal aqueous solution with a concentration of 2.28 M was prepared by dissolving NiSO4, CoSO4, and MnSO4 in ion-exchanged water in amounts such that the molar ratio of nickel:cobalt:manganese was 97.5:0.5:2.0. A 20 L batch reactor was filled with distilled water, a 20 wt% ammonia solution, and a 30 wt% sodium hydroxide aqueous solution, and the reactor temperature was increased while stirring at 500 rpm and purging with N2 gas.

[0383] When the internal solution temperature of the reactor reaches 60℃, the transition metal aqueous solution is quantitatively injected at a rate of 5.0 L / h and ammonia solution with a concentration of 20 wt% is injected at a rate of 3.0 L / h, and an aqueous sodium hydroxide solution is injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5. In the nucleation stage, the reaction is carried out for approximately 40 hours, and the average particle size D of the prepared nuclei 50 This was performed to be approximately 4.45 μm.

[0384] (2) Particle growth stage

[0385] After 1 hour, N2 gas was purged into the reaction solution at a rate of 300 L / h, and then the transition metal aqueous solution was supplied at a supply rate of 6 L / h (first flow rate) for 1 hour, and then supplied at a supply rate of 12 L / h (second flow rate) for 9 hours.

[0386] At the same time, the ammonia solution was supplied at a rate of 25 L / h for 10 hours, and then a sodium hydroxide solution was injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5 and the reaction solution temperature at 45℃ while carrying out the co-precipitation reaction.

[0387] When the volume of the reaction solution reached 20L, the supply of reactants was stopped, stirring was halted to allow the precursor intermediate to settle, the supernatant was removed, and the reaction was resumed. This process was repeated approximately 5 times to determine the average particle size D of the precursor particles. 50 The reaction was terminated when it reached 12 µm. The total reaction time was 80 hours.

[0388] After separating the precursor particles from the reaction solution, impurities were removed by washing, and the precursor for the cathode active material was prepared by drying in a 130°C drying oven for 10 hours and then sieving.

[0389] <Manufacturing of Cathode Active Material>

[0390] A positive electrode active material was prepared using the same method as in Example 1, except that the precursor for the positive electrode active material prepared above was used. The prepared positive electrode active material is LiNi 0.975 Co 0.005 Mn 0.02 It has a composition of O2, with an average particle size D 50 It was confirmed that this is 11.2 μm and has the form of a secondary particle.

[0391]

[0392] Comparative Example 2

[0393] <Manufacture of Precursors for Positive Active Materials>

[0394] (1) Nucleation stage

[0395] A transition metal aqueous solution with a concentration of 2.28 M was prepared by dissolving NiSO4, CoSO4, and MnSO4 in ion-exchanged water in amounts such that the molar ratio of nickel:cobalt:manganese was 97.5:0.5:2.0. A 20 L batch reactor was filled with distilled water, a 20 wt% ammonia solution, and a 30 wt% sodium hydroxide aqueous solution, and the reactor temperature was increased while stirring at 500 rpm and purging with N2 gas.

[0396] When the internal solution temperature of the reactor reaches 60℃, the transition metal aqueous solution is quantitatively injected at a rate of 5.0 L / h and ammonia solution with a concentration of 20 wt% is injected at a rate of 3.0 L / h, and an aqueous sodium hydroxide solution is injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5. In the nucleation step, the reaction is carried out for approximately 20 hours, and the average particle size D of the prepared nuclei 50 This was performed to make it approximately 3.6 µm.

[0397] (2) Particle growth stage

[0398] After 1 hour, N2 gas was purged into the reaction solution at a rate of 300 L / h, then the transition metal aqueous solution was supplied at a supply rate of 15 L / h (first flow rate) for 1 hour, and then supplied at a supply rate of 30 L / h (second flow rate) for 9 hours.

[0399] At the same time, the above ammonia solution was supplied at a rate of 25 L / h for 10 hours, and then a sodium hydroxide solution was injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5 and the reaction solution temperature at 60℃ while carrying out the co-precipitation reaction.

[0400] When the volume of the reaction solution reached 20L, the supply of reactants was stopped, stirring was halted to allow the precursor intermediate to settle, the supernatant was removed, and the reaction was resumed. This process was repeated approximately 5 times to determine the average particle size D of the precursor particles. 50 The reaction was terminated when it reached 12 µm. The total reaction time was 80 hours.

[0401] After separating the precursor particles from the reaction solution, impurities were removed by washing, and the precursor for the cathode active material was prepared by drying in a 130°C drying oven for 10 hours and then sieving.

[0402] <Manufacturing of Cathode Active Material>

[0403] A positive electrode active material was prepared using the same method as in Example 1, except that the precursor for the positive electrode active material prepared above was used. The prepared positive electrode active material is LiNi 0.975 Co 0.005 Mn 0.02 It has a composition of O2, with an average particle size D 50 It was confirmed that this is 11.2 μm and has the form of a secondary particle.

[0404]

[0405] Comparative Example 3

[0406] <Manufacture of Precursors for Positive Active Materials>

[0407] (1) Nucleation stage

[0408] A transition metal aqueous solution with a concentration of 2.28 M was prepared by dissolving NiSO4, CoSO4, and MnSO4 in ion-exchanged water in amounts such that the molar ratio of nickel:cobalt:manganese was 97.5:0.5:2.0. A 20 L batch reactor was filled with distilled water, a 20 wt% ammonia solution, and a 30 wt% sodium hydroxide aqueous solution, and the reactor temperature was increased while stirring at 500 rpm and purging with N2 gas.

[0409] When the internal solution temperature of the reactor reaches 60℃, the transition metal aqueous solution is quantitatively injected at a supply rate of 5.0 L / h and ammonia solution with a concentration of 20 wt% is injected at a supply rate of 3.0 L / h, and an aqueous sodium hydroxide solution is injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5. In the nucleation stage, the reaction is carried out for approximately 20 hours, and the average particle size D of the prepared nuclei 50 This was performed to make it approximately 4.6 µm.

[0410] (2) Particle growth stage

[0411] After 1 hour, N2 gas was purged into the reaction solution at a rate of 300 L / h, then the transition metal aqueous solution was supplied at a supply rate of 6 L / h (first flow rate) for 1 hour, and then supplied at a supply rate of 8.5 L / h (second flow rate) for 9 hours.

[0412] At the same time, the ammonia solution was supplied at a rate of 25 L / h for 10 hours, and then a sodium hydroxide solution was injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5 and the reaction solution temperature at 50℃ while carrying out the co-precipitation reaction.

[0413] When the volume of the reaction solution reached 20 L, the supply of reactants was stopped, stirring was halted to allow the precursor intermediate to settle, the supernatant was removed, and the reaction was resumed. This process was repeated about 5 times, and the reaction was terminated when the average particle size D50 of the precursor particles reached 12 µm. The total reaction time was 80 hours.

[0414] After separating the precursor particles from the reaction solution, impurities were removed by washing, and the precursor for the cathode active material was prepared by drying in a 130°C drying oven for 10 hours and then sieving.

[0415] <Manufacturing of Cathode Active Material>

[0416] A positive electrode active material was prepared using the same method as in Example 1, except that the precursor for the positive electrode active material prepared above was used. The prepared positive electrode active material is LiNi 0.975 Co 0.005 Mn 0.02 It has a composition of O2, with an average particle size D 50 It was confirmed that this is 11.2 μm and has the form of a secondary particle.

[0417]

[0418] Comparative Example 4

[0419] <Manufacture of Precursors for Positive Active Materials>

[0420] (1) Nucleation stage

[0421] A transition metal aqueous solution with a concentration of 2.28 M was prepared by dissolving NiSO4, CoSO4, and MnSO4 in ion-exchanged water in amounts such that the molar ratio of nickel:cobalt:manganese was 97.5:0.5:2.0. A 20 L batch reactor was filled with distilled water, a 20 wt% ammonia solution, and a 30 wt% sodium hydroxide aqueous solution, and the reactor temperature was increased while stirring at 500 rpm and purging with N2 gas.

[0422] When the internal solution temperature of the reactor reaches 60℃, the transition metal aqueous solution is quantitatively injected at a supply rate of 5.0 L / h and ammonia solution with a concentration of 20 wt% is injected at a supply rate of 3.0 L / h, and an aqueous sodium hydroxide solution is injected using a pH peristaltic pump to maintain the pH of the reaction solution at 11.5. In the nucleation stage, the reaction is carried out for approximately 50 hours, and the average particle size D of the nuclei produced 50 This was performed to make it 4.2㎛.

[0423] (2) Particle growth stage

[0424] After 1 hour, N2 gas was purged into the reaction solution at a rate of 300 L / h, then the transition metal aqueous solution was supplied at a supply rate of 7 L / h (first flow rate) for 1 hour, and then supplied at a supply rate of 13 L / h (second flow rate) for 9 hours.

[0425] At the same time, the ammonia solution was supplied at a rate of 25 L / h for 10 hours, and then a sodium hydroxide solution was injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5 and the reaction solution temperature at 50℃ while carrying out the co-precipitation reaction.

[0426] When the volume of the reaction solution reached 20L, the supply of reactants was stopped, stirring was halted to allow the precursor intermediate to settle, the supernatant was removed, and the reaction was resumed. This process was repeated approximately 5 times to determine the average particle size D of the precursor particles. 50 The reaction was terminated when it reached 12 µm. The total reaction time was 80 hours.

[0427] After separating the precursor particles from the reaction solution, impurities were removed by washing, and the precursor for the cathode active material was prepared by drying in a 130°C drying oven for 10 hours and then sieving.

[0428] <Manufacturing of Cathode Active Material>

[0429] A positive electrode active material was prepared using the same method as in Example 1, except that the precursor for the positive electrode active material prepared above was used. The prepared positive electrode active material is LiNi 0.975 Co 0.005 Mn 0.02 It has a composition of O2, with an average particle size D 50 It was confirmed that this is 11.2 μm and has the form of a secondary particle.

[0430]

[0431] Comparative Example 5

[0432] (1) Nucleation stage

[0433] A transition metal aqueous solution with a concentration of 2.28 M was prepared by dissolving NiSO4, CoSO4, and MnSO4 in ion-exchanged water in amounts such that the molar ratio of nickel:cobalt:manganese was 97.5:0.5:2.0. A 20 L batch reactor was filled with distilled water, a 20 wt% ammonia solution, and a 30 wt% sodium hydroxide aqueous solution, and the reactor temperature was increased while stirring at 500 rpm and purging with N2 gas.

[0434] When the internal solution temperature of the reactor reaches 60℃, the transition metal aqueous solution is quantitatively injected at a rate of 5.0 L / h and ammonia solution with a concentration of 20 wt% is injected at a rate of 3.0 L / h, and an aqueous sodium hydroxide solution is injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5. In the nucleation stage, the reaction is carried out for approximately 25 hours, and the average particle size D of the prepared nuclei 50 This was performed to make it 4.0㎛.

[0435] (2) Particle growth stage

[0436] After 1 hour, N2 gas was purged into the reaction solution at a rate of 300 L / h, then the transition metal aqueous solution was supplied at a supply rate of 12 L / h (first flow rate) for 1 hour, and then supplied at a supply rate of 27 L / h (second flow rate) for 9 hours.

[0437] At the same time, the ammonia solution was supplied at a rate of 25 L / h for 10 hours, and then a sodium hydroxide solution was injected using a pH peristaltic pump to maintain the reaction solution pH at 11.5 and the reaction solution temperature at 50℃ while carrying out the co-precipitation reaction.

[0438] When the volume of the reaction solution reached 20L, the supply of reactants was stopped, stirring was halted to allow the precursor intermediate to settle, the supernatant was removed, and the reaction was resumed. This process was repeated approximately 5 times to determine the average particle size D of the precursor particles. 50The reaction was terminated when it reached 12 µm. The total reaction time was 80 hours.

[0439] After separating the precursor particles from the reaction solution, impurities were removed by washing, and the precursor for the cathode active material was prepared by drying in a 130°C drying oven for 10 hours and then sieving.

[0440] <Manufacturing of Cathode Active Material>

[0441] A positive electrode active material was prepared using the same method as in Example 1, except that the precursor for the positive electrode active material prepared above was used. The prepared positive electrode active material is LiNi 0.975 Co 0.005 Mn 0.02 It has a composition of O2, with an average particle size D 50 It was confirmed that this is 11.2 μm and has the form of a secondary particle.

[0442]

[0443] Experimental Example 1 - Measurement of Particle Strength

[0444] For each of the precursors for the positive active material and the positive active material particles prepared in Example 1 and Comparative Examples 1 to 5 above, a pressure of 50 mN was applied in a vertical direction, the time at which cracks occurred in the particles was measured, the particle strength was calculated according to the following formula A, and the arithmetic mean value was calculated by repeating this 10 times to measure the particle strength value of each particle.

[0445] [Equation A]

[0446]

[0447] In the above [Equation A], P represents the pressure applied perpendicular to the particle at the point when a crack occurs in the target particle.

[0448] D represents the diameter of each particle assuming that the precursor for the positive active material and the positive active material particles prepared in Example 1 and Comparative Examples 1 to 5 are each perfectly spherical, and was calculated as the arithmetic mean of the horizontal diameter and the vertical diameter of the particle. At this time, the diameter of the particle was measured from the SEM image of the particle taken using a scanning electron microscope.

[0449] μ represents Poisson's ratio, and the normal strain (R) of the diameter of each of the above particles v ) and horizontal strain (R p It is defined as the ratio of ). At this time, the horizontal deformation of the particle was not considered, so the horizontal strain was calculated as 1.

[0450] The normal strain (R) of the diameter of each of the above particles v ) can be calculated according to the following [Equation B-1].

[0451] [Equation B-1]

[0452]

[0453] In the above [Equation B-1], D0 represents the diameter in the vertical direction of each particle before applying pressure to the particle, and D v represents the diameter in the vertical direction of the particle at the point where a crack occurs in each particle.

[0454]

[0455] Particle strength (MPa) of precursor for positive electrode active material Particle strength (MPa) of positive electrode active material Example 1 80 330 Comparative Example 1 30 220 Comparative Example 2 120 480 Comparative Example 3 25 180 Comparative Example 4 40 250 Comparative Example 5 95 400

[0456] Referring to Table 1 above, it can be seen that the precursor particles for the positive electrode active material prepared in Examples 1 and 2 have a particle strength satisfying the range of 70 MPa to 90 MPa, whereas the precursor particles for the positive electrode active material prepared in Comparative Examples 1 to 5 have a particle strength that does not satisfy the range of 70 MPa to 90 MPa. Meanwhile, it can be seen that the positive electrode active material prepared in Example 1 has a particle strength satisfying the range of 260 MPa to 390 MPa, whereas the positive electrode active materials prepared in Comparative Examples 1 to 5 have a particle strength that does not satisfy the range of 260 MPa to 390 MPa.

[0457] Cathode material manufacturing

[0458] Each of the positive active materials (first positive active material) prepared in Examples 1-2 and Comparative Examples 1-5 above and single-particle type particles and LiNi 0.94 Co 0.035 Mn 0.025 A cathode material was prepared by mixing a second cathode active material A, which has a composition of O2 and an average particle size of 3.9 μm, in a weight ratio of 50:50.

[0459] In addition, a cathode active material (first cathode active material) prepared in Comparative Example 1 above and a second cathode active material B prepared by the following method were mixed in a weight ratio of 50:50 to prepare a cathode material.

[0460] - Preparation of second positive active material B: (1) During the nucleation step when preparing the precursor for the positive active material, the average particle size D of the nuclei produced by the reaction 50 The fact that this was performed for about 0.5 hours until it becomes about 0.1 μm, and the average particle size D of the precursor particles in the particle formation stage. 50A precursor for a positive electrode active material was prepared in the same manner as in Example 1, except that the reaction was terminated when it reached 3.9 μm and the total reaction time was 5 hours. At this time, the particle strength of the precursor for the positive electrode active material was 80 MPa. (2) A second positive electrode active material was prepared in the same manner as in Example 1, except that the above precursor for the positive electrode active material was calcined at 750°C for 16 hours. At this time, the prepared second positive electrode active material was LiNi 0.94 Co 0.035 Mn 0.025 It was confirmed that it has a composition of O2, a particle strength of 330 MPa, and an average particle size of 3.9 μm. That is, the second cathode active material B has the same particle strength as Example 1 for the precursor and cathode active material, but differs from Example 1 in terms of average particle size.

[0461]

[0462] Experimental Example 2 - Initial Dose Characteristics

[0463] Each of the anode materials prepared above, PVdF as a binder, and carbon black as a conductive material were mixed with N-methylpyrrolidone in a weight ratio of 96.5:1.5:2 to prepare an anode slurry. The anode slurry was applied to one side of an aluminum thin film, dried at 100°C, and then rolled to produce an anode.

[0464] The cathode used lithium metal.

[0465] An electrode assembly was manufactured by interposing a porous polyethylene separator between the anode and cathode manufactured above, and a coin half-cell type lithium secondary battery was manufactured by placing the electrode assembly inside a battery case and injecting an electrolyte into the case. At this time, the electrolyte was prepared by dissolving 1.0 M lithium hexafluorophosphate (LiPF6) in an organic solvent mixed with ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate in a volume ratio of 3:4:3.

[0466] The above lithium secondary battery was charged to 4.25V at 25℃ in CC / CV mode with a C-rate of 0.2C and a cut-off condition of 0.005C, and then discharged to 2.5V in CC mode with a C-rate of 0.2C to measure the charge capacity and discharge capacity.

[0467] The results are shown in Table 2 below.

[0468]

[0469] Experimental Example 3 - Initial Resistance Characteristics

[0470] For a coin half-cell type lithium secondary battery with each of the cathode materials prepared above, it was charged to 4.25V at 25℃ in CC / CV mode, with a C-rate of 0.2C and a cut-off condition of 0.05C, and then discharged to 2.5V in CC mode and a C-rate of 0.2C (S-1). Afterwards, it was charged to 4.25V at 25℃ in CC / CV mode, with a C-rate of 0.2C and a cut-off condition of 0.05C, and then discharged in CC mode and a C-rate of 0.2C until it reached 50% of the discharge capacity measured in step S-1 (S-2).

[0471] At this time, the initial resistance (DCIR) was calculated by dividing the difference (voltage drop) between the voltage immediately after performing step S-2 and the voltage 10 seconds after performing step S-2 by the applied current (1.0C). The results are shown in Table 2 below.

[0472]

[0473] Experimental Example 4 - High-temperature life characteristics

[0474] For a coin half-cell type lithium secondary battery using the cathode material prepared above, charging to 4.25V under CC-CV mode, a C-rate of 0.33C, and a cut-off condition of 0.05C at 45℃, and discharging to 2.5V under CC mode and a C-rate of 0.33C constituted one cycle, and 30 cycles of charge and discharge were performed, after which the capacity retention rate relative to the initial capacity after 30 cycles was measured. The results are shown in Table 2 below.

[0475] Cathode Material 1st Cathode Active Material 2nd Cathode Active Material Charging Capacity [mAh / g] Discharging Capacity [mAh / g] Initial Resistance [@SOC 50%, Ω] Capacity Retention Rate [@30 cycle, %] A Example 1 2nd Cathode Active Material A247.4218.59.893.2C Comparative Example 1 2nd Cathode Active Material A246.2215.810.189.4D Comparative Example 2 2nd Cathode Active Material A245.0212.510.892.4E Comparative Example 3 2nd Cathode Active Material A245.5214.610.287.5F Comparative Example 4 2nd Cathode Active Material A246.5216.19.890.2G Comparative Example 5 2nd Cathode Active Material A245.4214.110.692.8H Comparative Example 1 2nd Cathode Active Material B248.1219.811.285.4

[0476] Referring to Table 2 above, it can be seen that the lithium secondary battery using the cathode materials A and B has lower initial capacity and capacity retention rate at high temperatures, and higher initial resistance than the lithium secondary battery using the cathode materials C to G. Referring to Table 2 above, it can be seen that the lithium secondary battery using the cathode material H has a discharge capacity similar to or superior to that of the lithium secondary battery using the cathode materials A to C, but has very high initial resistance and a very low capacity retention rate at high temperatures.

[0477] This is determined to be due to the fact that by applying the cathode active materials prepared in Examples 1 and 2 to the first cathode active material, which is a large-particle cathode active material, the first cathode active material with a large particle size can have appropriate particle strength, and accordingly, particle breakage during the rolling process is relatively reduced compared to the cathode materials C to H.

[0478] In particular, the above-mentioned cathode material H is a cathode material in which the first cathode active material, which has a large particle size, is a cathode active material having a particle strength at the level of Comparative Example 1, which is the same as the conventional one, and the second cathode active material, which has a small particle size, is a cathode active material having a particle strength identical to that of the cathode active material and the cathode active material prepared in Example 1. As the particle strength of the second cathode active material is lower than that of the conventional one, the reaction area increases, and while there may be advantages in terms of initial capacity, particle breakage may occur in both the first and second cathode active materials during rolling, and particle cracking may occur in the second cathode active material, so it is judged that the initial resistance and high-temperature life characteristics become even more inferior.

Claims

1. A lithium nickel-based oxide containing 80 mol% or more of nickel among all metals excluding lithium, and A positive active material having a particle strength of 260 MPa to 390 MPa.

2. In Paragraph 1, Average particle size (D) of the above positive active material 50 ) is a positive active material having a size of 5㎛ to 18㎛.

3. In Paragraph 1, The above positive active material is a positive active material having a SPAN value of 0.2 to 0.7 defined by the following formula C. [Equation C] SPAN = (D 90 -D 10 ) / D 50 In the above equation C, D 90, D 50, D 10 These are the particle size values ​​when the cumulative volume is 90%, 50%, and 10%, respectively, in the volume-based particle size distribution of the above-mentioned positive active material.

4. In Paragraph 1, The above positive active material is a positive active material comprising secondary particles.

5. A precursor for an anode active material comprising a nickel-based hydroxide containing 80 mol% or more of nickel among the total metals, and having a particle strength of 70 to 90 MPa.

6. In Paragraph 5, The above precursor for the positive electrode active material has an average particle size (D 50 A precursor for a positive electrode active material having a thickness of 5㎛ to 18㎛.

7. A nucleation step of forming a precursor nucleus for an anode active material by co-precipitating while supplying an aqueous transition metal solution, an ammonium cation complex forming agent, and a basic compound to a reactor; and A particle growth step comprising growing precursor particles for a positive electrode active material by co-precipitating a reaction solution in which a precursor nucleus for the positive electrode active material is formed, while supplying an aqueous transition metal solution, an ammonium cation complex forming agent, and a basic compound to the reaction solution; A method for manufacturing a precursor for an anode active material, wherein in the particle growth step, the transition metal aqueous solution is supplied at a first flow rate of 8 L / h to 11.5 L / h and then supplied at a second flow rate of 20 L / h to 30 L / h.

8. In Paragraph 7, A method for manufacturing a precursor for an anode active material, wherein the co-precipitation reaction in the particle growth step is performed at a temperature of 46 to 59°C.

9. In Paragraph 7, A method for manufacturing a precursor for an anode active material, wherein in the particle growth step, the transition metal aqueous solution is supplied at a first flow rate for 2 hours or less, and then supplied at a second flow rate for 7 to 13 hours.

10. In Paragraph 7, A method for manufacturing a precursor for an anode active material, wherein the second flow rate is at least 2.3 times the first flow rate.

11. A first positive electrode active material; and a second positive electrode active material; comprising, The first positive active material has an average particle size (D) greater than that of the second positive active material. 50 ) is large, The above-mentioned first positive active material is a positive active material according to any one of claims 1 to 4, a positive material.

12. In Paragraph 11, The above second positive active material is a positive material comprising single-particle type particles.

13. In Paragraph 11, The above second positive active material comprises a lithium nickel-based oxide containing 80 mol% or more of nickel among the total metals excluding lithium, and is a positive material.

14. In Paragraph 11, Average particle size (D) of the second positive active material above 50 ) is a cathode material having a size of 1㎛ to 5㎛.

15. In Paragraph 11, The above second positive active material is a positive material having a ratio of particles with a particle size of 1 μm or less of 3.0 volume% or less.

16. In Paragraph 11, The above second positive active material is a positive material having a particle strength of 600 MPa to 900 MPa.

17. In Paragraph 11, The above second positive active material is a positive material having a span value of 0.7 to 1.5 as defined by the following formula C-1. [Equation C-1] SPAN = (D 90 -D 10 ) / D 50 In the above equation C-1, D 90, D 50, D 10 These are the particle size values ​​when the cumulative volume is 90%, 50%, and 10%, respectively, in the volume-based particle size distribution of the second positive active material.

18. In Paragraph 11, A cathode material comprising the first cathode active material and the second cathode active material in a weight ratio of 2:8 to 8:

2.

19. A cathode comprising a cathode material according to paragraph 11.

20. A lithium secondary battery comprising: a positive electrode according to claim 19; a negative electrode disposed opposite to the positive electrode; and an electrolyte.

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