The anode material, the anode electrode, and the lithium secondary battery include this anode electrode.

Abstract

The invention relates to an anode material comprising an active anode material consisting of: lithium nickel oxide particles in the form of secondary particles which are aggregates of primary particles, in which, among all metals except lithium, the content of Ni is between 50 mol% and 90 mol%; and a boron (B)-containing coating formed on the surface of the lithium nickel oxide particles. The specific surface area BET of the anode material is between 0.41 m2 / g and 0.59 m2 / g, and the mean crystal seed size of the anode material is 155 nm or greater.

Description

Cathode material, cathode containing same, and lithium secondary battery Cross-citation with related applications This application claims the benefit of priority to Korean Patent Application No. 10-2023-0189917, filed December 22, 2023, and Korean Patent Application No. 10-2024-0166754, filed November 20, 2024, the entire contents of which are incorporated herein by reference. Technical field The present invention relates to a cathode material, a cathode comprising the same, and a lithium secondary battery. Lithium secondary batteries are generally composed of a positive electrode, a negative electrode, a separator, and an electrolyte, and the positive electrode and negative electrode include an active material capable of intercalation and deintercalation of lithium ions. Lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2 or LiMnO4, etc.), and lithium iron phosphate compound (LiFePO4) have been used as positive active materials for lithium secondary batteries. Among these, lithium cobalt oxide has the advantages of high operating voltage and excellent capacity characteristics, but the price of cobalt, which is the raw material, is high and its supply is unstable, making it difficult to commercially apply it to large-capacity batteries. Lithium nickel oxide has poor structural stability, making it difficult to implement sufficient life characteristics. On the other hand, lithium manganese oxide has the problem of excellent stability but poor capacity characteristics. Therefore, lithium composite transition metal oxides containing two or more transition metals have been developed to complement the problems of lithium transition metal oxides containing only Ni, Co, or Mn, and among these, lithium nickel cobalt manganese oxide containing Ni, Co, and Mn is widely used in the field of electric vehicle batteries. Meanwhile, in the case of the cathode material using conventional lithium nickel cobalt manganese oxide, the specific surface area is high and the resistance characteristics are excellent, but the particles are easily broken during the electrode manufacturing process, resulting in a lot of fine powder generation, and there are many side reactions with the electrolyte, resulting in a lot of gas generation during high-temperature storage. To solve this, a method of lowering the specific surface area has been proposed, but in cases where the specific surface area is too low, the initial resistance increases, resulting in a decrease in the output characteristics and a decrease in the initial capacity characteristics. Therefore, there is a need for the development of a cathode material that has excellent output characteristics due to low resistance, as well as excellent high-temperature storage characteristics. The present invention is intended to solve the above problems, and to provide a cathode material having excellent output characteristics due to low resistance and excellent high-temperature storage characteristics, and a cathode and a lithium secondary battery including the cathode material. [1] The present invention is a cathode material including a cathode active material including lithium nickel-based oxide particles having a content of nickel of 50 mol% to 90 mol% among all metals excluding lithium and having a secondary particle form in which a plurality of primary particles are aggregated; and a coating layer formed on the surface of the lithium nickel-based oxide particles and containing boron (B); wherein the BET specific surface area of ​​the cathode material is 0.41 m 2 / g to 0.59m 2 / g, and the average crystallite size of the cathode material is 155 nm or more. [2] In the present invention, in the above [1], the average crystallite size of the cathode material may be 155 nm to 170 nm. [3] In the present invention, in the above [1] or [2], the lithium nickel-based oxide particles may be represented by the following chemical formula 1. [Chemical Formula 1] Li a [Ni b Co c M 1d M 2 e ]O2 In the above chemical formula 1, M 1 is Mn, Al or a combination of these, and M 2 is at least one selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and 0.80≤a≤1.20, 0.50≤b≤0.90, 0 <c≤0.40, 0<d≤0.40, 0≤e≤0.10이다. [4] In at least one of the above [1] to [3], the boron (B) may be included in an amount of 500 ppm to 1000 ppm based on the total weight of the cathode material. [5] In at least one of the above [1] to [4], the residual lithium amount of the positive electrode material may be 0.2 wt% to 0.4 wt%. [6] In at least one of the above [1] to [5], the cation mixing ratio of the positive electrode material may be 2.5 at% or less. [7] The present invention is characterized in that in at least one of the above [1] to [6], the cathode material has an average particle diameter D 50 These large particles are 6 ㎛ to 20 ㎛ in size and have an average particle diameter D 50 It may contain small particles of 0.1 μm to 5.5 μm. [8] The present invention is characterized in that in at least one of the above [1] to [7], the cathode material has an average particle diameter D 50 These large particles are 6 ㎛ to 20 ㎛ in size and have an average particle diameter D 50 It includes small particles having a size of 0.1 ㎛ to 5.5 ㎛, and the large particles and small particles may be included in a weight ratio of 60:40 to 80:20. [9] The present invention provides a cathode comprising a cathode material according to at least one of [1] to [8].

[0010] The present invention provides a lithium secondary battery including a positive electrode according to the above [9]. The cathode material according to the present invention has a BET specific surface area of ​​0.41 m 2 / g to 0.59m 2 / g, and the average crystallite size is 155 nm or more. In the case of a lithium secondary battery using a cathode material satisfying all of the above conditions, the initial resistance characteristics and high-temperature storage characteristics are excellent. Hereinafter, the present invention will be described more preferably. The terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as having meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best manner. In the present invention, the “specific surface area” is measured by the BET method, and can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using BELSORP-mini II of BEL Japan. In the present invention, “single particle type” means a particle composed of 50 or fewer nodules, and is a concept that includes a single particle composed of one nodule and a pseudo-single particle that is a composite of 2 to 50 nodules. The above “nodule” is a sub-particle unit that constitutes a single particle and a pseudo-single particle, and may be a single crystal without a crystalline grain boundary, or a polycrystal that has no apparent grain boundary when observed under a field of view of 5,000 to 20,000 times using a scanning electron microscope. In the present invention, "secondary particle" means a particle formed by agglomeration of a plurality of primary particles, for example, tens to hundreds of primary particles. Preferably, the secondary particle may be an agglomerate of 51 or more primary particles. In the present invention, “particle” is a concept including any one or all of a single particle, a quasi-single particle, a primary particle, a nodule, and a secondary particle. In the present invention, "average particle diameter D 50 "It means the particle size at 50% of the volume cumulative particle size distribution of the positive electrode active material powder or positive electrode material powder, and can be measured using the laser diffraction method. For example, after dispersing the positive electrode active material powder or positive electrode material powder in a dispersion medium, it can be measured by introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasonic waves of about 28 kHz with an output of 60 W, obtaining a volume cumulative particle size distribution graph, and then finding the particle size corresponding to 50% of the volume cumulative amount. In the present invention, "crystallite" means a particle unit having substantially the same crystal orientation, which can be confirmed through EBSD (Electron Backscatter Diffraction) analysis. Preferably, it is a minimum particle unit displayed in the same color in an IPF map obtained by EBSD analysis of a cross-section of a cathode active material cut through ion milling. In the present invention, the "average crystallite size" can be quantitatively analyzed using X-ray diffraction analysis (XRD) by Cu Kα X-rays. Preferably, the average crystallite size of the crystal grains can be quantitatively analyzed by putting the particles to be measured in a holder, irradiating the particles with X-rays, and analyzing the diffraction grating generated. Sampling was prepared by putting a powder sample of the target particle into a groove in the center of a general powder holder, smoothing the surface using a slide glass, and making the sample height the same as the edge of the holder. Then, X-ray diffraction analysis was performed using a Bruker D8 Endeavor (light source: Cu Kα, λ=1.54Å) equipped with a LynxEye XE-T position sensitive detector, under the conditions of a step size of 0.02 degrees, and a total scan time of about 60 minutes for a FDS of 0.5°, 2θ=10° to 125° range. For the measured data, Rietveld refinement was performed considering the charge (+3 for metal ions at the transition metal site and +2 for Ni ions at the Li site) and cation mixing at each site. When analyzing the grain size, instrumental brodadening was considered using the Fundamental Parameter Approach (FPA) implemented in the Bruker TOPAS program, and the entire peaks of the measurement range were used for fitting. Among the peak types available in TOPAS, only the Lorenzian contribution was used for the peak shape fitting with the First Principle (FP), and strain was not considered. In the present invention, the "cation mixing ratio" is the nickel ion (Ni) based on the total amount of lithium sites (Li sites) in the lithium layer of the lithium nickel oxide having a layered structure. 2+) is mixed in, and refers to the ratio (%) occupied by the mixed particles, and means the value measured through X-ray diffraction analysis (XRD). Preferably, the X-ray diffraction analysis can be performed as follows. Using a Bruker D8 Endeavor (light source: Cu Kα, λ=1.54Å) equipped with a LynxEye XE-T position sensitive detector, X-ray diffraction analysis was performed under the conditions of a step size of 0.02 degree and a total scan time of approximately 60 minutes for the FDS 0.5°, 2θ=10° to 125° region. For the measured data, Rietveld refinement was performed considering the charge at each site (metal ions of the transition metal site are +3, Ni ions of the Li site are +2) and cation mixing. In the analysis of grain size, instrumental brodadening was considered using the Fundamental Parameter Approach (FPA) implemented in the Bruker TOPAS program, and the entire peaks of the measurement range were used for fitting. The peak shape was fitted using only the Lorenzian contribution as the FP (First Principle) among the peak types available in TOPAS, and strain was not considered at this time. The cathode material according to the present invention, the cathode comprising the same, and the lithium secondary battery comprise at least one of the following disclosed configurations, and may comprise any combination between technically possible configurations among the following configurations. Bipolar material Hereinafter, the cathode material according to the present invention will be described. The cathode material according to the present invention is a cathode material including a cathode active material including lithium nickel-based oxide particles having a nickel content of 50 mol% to 90 mol% among the total metal excluding lithium and having a secondary particle form in which a plurality of primary particles are aggregated; and a coating layer formed on the surface of the lithium nickel-based oxide particles and including boron (B); and the BET specific surface area of ​​the cathode material is 0.41 m 2 / g to 0.59m 2 / g, and the average crystallite size of the cathode material is 155 nm or more. Lithium nickel oxide particles, which were previously used as positive electrode active materials, were generally 0.6 m 2 / g to 1.9m 2 / g level. These conventional positive electrode active materials have high internal porosity and thus excellent resistance characteristics, but the particles are easily broken during electrode manufacturing, resulting in a lot of fine powder generation, and there are many side reactions with the electrolyte, resulting in excessive gas generation during high-temperature storage. On the other hand, reducing the specific surface area of ​​the positive electrode active material reduces particle breakage, thereby reducing the amount of gas generated during high-temperature storage, but this increases the initial resistance, resulting in problems such as lower output and capacity characteristics. The inventors of the present invention have conducted continuous research to solve this problem and have achieved a BET surface area of ​​0.41 m 2 / g to 0.59m 2 / g level, and by controlling the average crystallite size of the cathode material to 155 nm or more, it was found that excellent high-temperature storage characteristics can be realized by reducing the initial resistance while reducing the amount of gas generated during high-temperature storage, thereby realizing excellent high-temperature storage characteristics. Thus, the present invention was completed. According to one embodiment of the present invention, the BET surface area of ​​the cathode material is 0.41 m 2 / g to 0.59m 2 / g. Preferably, 0.41m 2 / g or more or 0.42m 2 / g can be greater than or equal to 0.59m 2 / g or less, 0.58m 2 / g or less, 0.57m 2 / g or less, 0.56m 2 / g or less or 0.55m 2 / g or less, more preferably 0.41m 2 / g to 0.55m 2 / g. The BET surface area of ​​the cathode material is 0.41 m 2 / g or less, the crystal structure becomes unstable due to over-sintering or increased sintering temperature during the manufacture of the cathode material, and the amount of surface residual lithium increases, causing problems such as increased gas generation during high-temperature storage. The specific surface area of ​​the cathode material is 0.59 m 2 / If it exceeds g, the particle breakage during rolling increases, which increases the contact area with the electrolyte, and the electrolyte hygroscopicity at the interface increases, so there is a problem that the amount of gas generated increases during high-temperature storage. Therefore, when the above range is satisfied, the initial resistance is reduced, which implements excellent output characteristics, while the amount of gas generated during high-temperature storage is reduced, which implements excellent high-temperature storage characteristics. According to one embodiment of the present invention, the average crystallite size of the positive electrode material is 155 nm or more, preferably 155 nm or more, and may be 190 nm or less, 185 nm or less, 180 nm or less, 175 nm or less, or 170 nm or less, and more preferably 155 nm to 170 nm. When the average crystallite size of the positive electrode material is less than 155 nm, a plurality of primary particles in the secondary particle are randomly arranged, and as a result, the lithium ion movement paths in the secondary particle are diversified, thereby increasing unnecessary lithium ion movement. That is, since the movement of lithium through the primary particle interface in the secondary particle is hindered, a problem occurs in which the initial resistance increases, and a problem occurs in which the specific surface area increases, thereby increasing the amount of gas generated. Therefore, when the above range is satisfied, excellent initial resistance characteristics and high-temperature storage characteristics can be implemented. In addition, according to the research of the present inventors, when the BET specific surface area range and the average crystallite size range of the cathode material are simultaneously satisfied, excellent output characteristics and excellent high-temperature storage characteristics are simultaneously implemented. That is, when the BET specific surface area of ​​the cathode material is 0.41 m 2 / g to 0.59m 2 Even if / g is satisfied, if the average crystallite size is less than 155 nm, or if the average crystallite size of the cathode material is 155 nm or more but the BET surface area is outside the above range, the effect of improving the output characteristics and reducing the amount of gas generated during high-temperature storage is minimal. For example, if both the BET surface area and the average crystallite size of the cathode material are not controlled within a certain range, the contact area with the electrolyte, the stability of the crystal structure, the efficiency of the lithium path due to the crystal grain size, etc. are not organically combined as desired, so there is a problem that the output characteristics deteriorate and the amount of gas generated increases during high-temperature storage. Meanwhile, the BET specific surface area and the average crystallite size of the positive electrode material are controlled by a complex interaction of the BET specific surface area and the average crystallite size of the positive electrode active material included in the positive electrode material, the BET specific surface area and the average particle size of the precursor used in the manufacture of the positive electrode active material, the molar ratio of lithium and transition metal during the sintering of the precursor, the sintering temperature during the manufacture of the positive electrode active material and the positive electrode material, the content of the coating element, etc. In this case, when the positive electrode material has a bimodal particle size distribution having a positive electrode active material having a large average particle diameter and a positive electrode active material having a small average particle diameter, the BET specific surface area and the average crystallite size of each positive electrode active material and the content of the coating element can be controlled by a complex interaction of, but the present invention is not limited thereto. At this time, the BET specific surface area and the average crystallite size of the positive electrode material are values ​​measured from the positive electrode material powder, and are distinct from the BET specific surface area and the average crystallite size of individual positive electrode active material particles. For example, when a positive electrode active material having a large average particle size and a positive electrode active material having a small average particle size are included, the BET specific surface area and the average crystallite size of each may be different from the BET specific surface area and the average crystallite size of the entire positive electrode material. Hereinafter, a cathode material according to the present invention will be preferably described. According to one embodiment of the present invention, the cathode material includes a cathode active material including lithium nickel-based oxide particles in the form of secondary particles in which a plurality of primary particles are aggregated, and a coating layer formed on the surface of the lithium nickel-based oxide particles and including boron (B). According to one embodiment of the present invention, the lithium nickel-based oxide particles may have a content of Ni among metal elements other than lithium of 50 mol% to 90 mol%, preferably 60 mol% to 90 mol%, more preferably 60 mol% to 85 mol%, and even more preferably 65 mol% to 80 mol%. For example, the lithium nickel-based oxide particles can be represented by the following chemical formula 1. [Chemical Formula 1] Li a [Ni b Co c M 1 d M 2 e ]O2 In the above chemical formula 1, M 1 can be Mn, Al or a combination thereof. Above M 2 may be at least one selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and preferably may be at least one selected from the group consisting of Ti, Zr, Y, and Mg. When the above condition is satisfied, it may be preferable in terms of promoting particle growth during sintering or improving crystal structure stability. The above a represents the molar ratio of lithium in the lithium nickel-based oxide particles, and can be 0.80≤a≤1.20, 0.90≤a≤1.10, or 1.00≤a≤1.10. When the above range is satisfied, it is preferable in that the resistance can be reduced while reducing the amount of gas generated. The above b represents the molar ratio of nickel among the metals excluding lithium in the lithium nickel-based oxide particles, and may be 0.50≤b≤0.90, 0.60≤b≤0.90, 0.60≤b≤0.85, or 0.65≤b≤0.80. The above c represents the molar ratio of cobalt among metals other than lithium in lithium nickel oxide particles, and is 0. <c≤0.40, 0<c≤0.25 또는 0<c≤0.15일 수 있다. The above d is M among the metals other than lithium in the lithium nickel oxide particles. 1 It represents the molar ratio of elements, 0 <d≤0.40, 0<d≤0.30 또는 0<d≤0.25일 수 있다. The above e is M among the metals except lithium in the lithium nickel oxide particles. 2 It represents the molar ratio of elements, and can be 0≤e≤0.10, 0≤e≤0.08, or 0≤e≤0.05. According to one embodiment of the present invention, the lithium nickel-based oxide particles are in the form of secondary particles in which a plurality of primary particles are aggregated. When the lithium nickel-based oxide particles are in the form of secondary particles, a high rolling density can be implemented, so that the energy density per volume can increase. In addition, when a coating layer including boron (B) is formed on the surface of the lithium nickel-based oxide particles while satisfying the BET specific surface area range and the average crystallite size range of the above-described positive electrode material, it can be an appropriate condition for implementing better output characteristics and high-temperature storage characteristics. For example, when the lithium nickel-based oxide particles are in the form of single particles rather than secondary particles, a large amount of inactive rock salt structures are generated on the surface of the particles, which makes ion transfer difficult, and the average crystallite size is excessively high, which causes poor lithium ion movement and inferior resistance characteristics. In addition, in the case of single particle lithium nickel-based oxide, when a washing process is performed, an inactive structural material is formed on the surface, which increases resistance, so that it is difficult to control the amount of residual lithium on the surface without going through a washing process. Therefore, the effects according to the present invention are excellently implemented when the lithium nickel-based oxide particles are in the form of secondary particles. According to one embodiment of the present invention, the coating layer is formed on the surface of the lithium nickel-based oxide particle and includes boron (B). When the coating layer including boron (B) is formed on the surface of the lithium nickel-based oxide particle, contact between the electrolyte and the lithium nickel-based oxide particle is minimized by the coating layer, thereby suppressing side reactions between the electrolyte and the lithium nickel-based oxide and the elution of transition metals, thereby obtaining the effect of improving the life characteristics. According to one embodiment of the present invention, the boron (B) may be included in an amount of 500 ppm to 1000 ppm, preferably 600 ppm to 900 ppm, and more preferably 700 ppm to 900 ppm based on the total weight of the cathode material. When the above range is satisfied, it is preferable in that the dissolution of transition metals can be suppressed while particle breakage during rolling can be reduced and the resistance can not be excessively increased. According to one embodiment of the present invention, the amount of residual lithium in the positive electrode material may be 0.2 wt% to 0.4 wt%, preferably 0.25 wt% to 0.35 wt%, and more preferably 0.25 wt% to 0.30 wt%. When the above range is satisfied, it is preferable in that the problem of the surface of the positive electrode active material collapsing due to excessive washing can be prevented, while also preventing an increase in resistance due to residual lithium. According to one embodiment of the present invention, the cation mixing ratio of the positive electrode active material may be 2.5 at% or less, preferably 1.0 at% to 2.5 at%, and more preferably 1.0 at% to 2.0 at%. When the above range is satisfied, the resistance characteristics may be improved by having a high degree of crystal structure perfection. Here, at% means atomic%. According to one embodiment of the present invention, the cathode material has an average particle diameter D 50 These large particles are 6 ㎛ to 20 ㎛ in size and have an average particle diameter (D 50 ) may include small particles having a size of 0.1 μm to 5.5 μm. The average particle diameter D is greater than the above particles 50 When these small particles are included, the gaps between the large particles with a large average particle diameter are filled with small particles with a small average particle diameter during the manufacture of the positive electrode, thereby increasing the electrode density and increasing the contact area between the particles, thereby improving the energy density. According to one embodiment of the present invention, the average particle diameter D of the particles50 The silver may be 6 ㎛ to 20 ㎛, preferably 6 ㎛ to 15 ㎛, more preferably 7 ㎛ to 11 ㎛. According to one embodiment of the present invention, the average particle diameter D of the small particles 50 The silver may be 0.1 ㎛ to 5.5 ㎛, preferably 1 ㎛ to 5 ㎛, and more preferably 2 ㎛ to 5 ㎛. When the above range is satisfied, the energy density may be excellent. According to one embodiment of the present invention, the particle includes a lithium nickel-based oxide particle in the form of a secondary particle in which a plurality of primary particles are aggregated, and the lithium nickel-based oxide particle can be represented by the following chemical formula 2. [Chemical formula 2] Li a1 Ni b1 Co c1 M 3 d1 M 4 e1 O2 In the above chemical formula 2, M 3 can be Mn, Al or a combination thereof. Above M 4 may be at least one selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo. The above a1 represents the molar ratio of lithium in the lithium nickel-based oxide particles, and may be 0.80≤a1≤1.20, 0.90≤a1≤1.10, or 1.00≤a1≤1.10. The above b1 represents the molar ratio of nickel among metals excluding lithium in the lithium nickel-based oxide particles, and may be 0.30≤b1<1.00, 0.40≤b1≤0.90, 0.50≤b1≤0.85, or 0.65≤b≤0.80. The above c1 represents the molar ratio of cobalt among metals other than lithium in lithium nickel oxide particles, 0 <c1≤0.70, 0<c1≤0.40 또는 0<c1≤0.20일 수 있다. The above d1 is M among the metals except lithium in the lithium nickel oxide particles. 1 It represents the molar ratio of elements, 0 <d1≤0.70, 0<d1≤0.40 또는 0<d1≤0.30일 수 있다. The above e1 is M among the metals except lithium in the lithium nickel oxide particles. 2 It represents the molar ratio of elements, and can be 0≤e1≤0.10, 0≤e1≤0.08, or 0≤e1≤0.05. According to one embodiment of the present invention, the large particle may include a lithium nickel-based oxide particle and a coating layer formed on the surface of the lithium nickel-based oxide particle and containing boron (B). When the coating layer is formed on the surface of the lithium nickel-based oxide particle, contact between the electrolyte and the lithium nickel-based oxide particle is suppressed by the coating layer, thereby obtaining an effect of reducing transition metal elution or gas generation due to a side reaction with the electrolyte. According to one embodiment of the present invention, the coating layer may further include one or more coating elements selected from the group consisting of Al, Ti, W, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb. Mo, Sr, Sb, Bi, Si and S. When the above condition is satisfied, it may be preferable in terms of being able to suppress the occurrence of side reactions of the electrolyte. According to one embodiment of the present invention, the small particle includes a lithium nickel-based oxide particle in the form of a secondary particle in which a plurality of primary particles are aggregated, and the lithium nickel-based oxide particle can be represented by the following chemical formula 3. [Chemical Formula 3] Li a2 Ni b2 Co c2 M 5 d2 M 6 e2 O2 In the above chemical formula 3, M 5can be Mn, Al or a combination thereof. Above M 6 may be at least one selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo. The above a2 represents the molar ratio of lithium in the lithium nickel-based oxide particles, and may be 0.80≤a1≤1.20, 0.90≤a1≤1.10, or 1.00≤a1≤1.10. The above b2 represents the molar ratio of nickel among metals excluding lithium in the lithium nickel-based oxide particles, and may be 0.30≤b1<1.00, 0.40≤b1≤0.90, 0.50≤b1≤0.85, or 0.65≤b≤0.80. The above c2 represents the molar ratio of cobalt among metals other than lithium in lithium nickel oxide particles, and is 0. <c1≤0.70, 0<c1≤0.40 또는 0<c1≤0.20일 수 있다. The above d2 is M among the metals except lithium in the lithium nickel oxide particles. 1 It represents the molar ratio of elements, 0 <d1≤0.70, 0<d1≤0.40 또는 0<d1≤0.30일 수 있다. The above e2 is M among the metals except lithium in the lithium nickel oxide particles. 2 It represents the molar ratio of elements, and can be 0≤e1≤0.10, 0≤e1≤0.08, or 0≤e1≤0.05. According to one embodiment of the present invention, according to one embodiment of the present invention, the small particle may include a lithium nickel-based oxide particle and a coating layer formed on the surface of the lithium nickel-based oxide particle and including boron (B). When the coating layer is formed on the surface of the lithium nickel-based oxide particle, contact between the electrolyte and the lithium nickel-based oxide particle is suppressed by the coating layer, thereby obtaining the effect of reducing the elution of transition metal or gas generation due to a side reaction with the electrolyte. According to one embodiment of the present invention, the large particles and small particles may be included in a weight ratio of 60:40 to 80:20, and preferably in a weight ratio of 65:35 to 75:25. When the above range is satisfied, the effect of suppressing particle breakage during rolling and the energy density may be excellent. anode Next, the anode according to the present invention will be described. The positive electrode according to the present invention comprises the positive electrode material according to the present invention described above. Preferably, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector and comprising the positive electrode material of the present invention described above. In the above positive electrode, the positive electrode collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode collector may typically have a thickness of 3 to 500 ㎛, and fine unevenness may be formed on the surface of the positive electrode collector to increase the adhesion of the positive electrode active material. For example, it may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc. In addition, the positive electrode active material layer may include a conductive material and a binder together with the positive electrode material described above. The conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without special restrictions. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, and carbon nanotube; metal powder or metal fiber 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 the like, and one of these may be used alone or a mixture of two or more may be used. The conductive material may be typically included in an amount of 1 to 30 wt%, preferably 1 to 20 wt%, and more preferably 1 to 10 wt%, based on the total weight of the positive electrode active material layer. The above binder serves to improve the adhesion between the positive electrode active material particles and the adhesiveness between the positive electrode active material and the positive electrode current collector. Specific examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, 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 may be used alone or a mixture of two or more thereof may be used. The above binder may be included in an amount of 1 to 30 wt%, preferably 1 to 20 wt%, and more preferably 1 to 10 wt%, based on the total weight of the positive electrode active material layer. The above positive electrode can be manufactured according to a conventional positive electrode manufacturing method. For example, the positive electrode can be manufactured by mixing a positive electrode active material, a binder, and / or a conductive agent in a solvent to manufacture a positive electrode slurry, applying the positive electrode slurry onto a positive electrode current collector, and then drying and rolling. At this time, the types and contents of the positive electrode active material, binder, and conductive agent are as described above. The solvent may be a solvent generally used in the relevant technical field, and may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, taking into account the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity during subsequent coating for manufacturing the positive electrode. Alternatively, the positive electrode may be manufactured by casting the positive electrode slurry onto a separate support, peeling the resulting film from the support, and laminating the resulting film onto a positive electrode current collector. Lithium secondary battery Hereinafter, a lithium secondary battery according to the present invention will be described. The lithium secondary battery of the present invention comprises the positive electrode according to the present invention. Preferably, it may comprise the positive electrode, the negative electrode, the separator, and the electrolyte. In addition, the lithium secondary battery may optionally further comprise a battery container that accommodates the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container. (cathode) The above negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector. The above negative electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change 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., an aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 to 500 ㎛, and, like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a non-woven fabric. The above negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material. As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO β (0 <β< 2), SnO2, vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metal compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative active material. In addition, both low-crystallinity carbon and high-crystallinity carbon may be used as the carbon material. Soft carbon and hard carbon are representative examples of low-crystallinity carbon, and high-crystallinity carbon is representative examples of amorphous, plate-like, flaky, spherical or fibrous natural graphite or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes. The conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without special restrictions. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, carbon fiber, and carbon nanotube; metal powder or metal fiber 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 the like, and one of these may be used alone or a mixture of two or more may be used. The conductive material may be typically included in an amount of 1 to 30 wt%, preferably 1 to 20 wt%, and more preferably 1 to 10 wt%, based on the total weight of the negative electrode active material layer. The above binder serves to improve the adhesion between negative active material particles and the adhesive strength between the negative active material and the negative current collector. Specific examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one kind alone or a mixture of two or more kinds thereof may be used. The above binder may be included in an amount of 1 to 30 wt%, preferably 1 to 20 wt%, and more preferably 1 to 10 wt%, based on the total weight of the negative electrode active material layer. The above negative electrode active material layer may be manufactured by, for example, applying a negative electrode slurry containing a negative electrode active material and optionally a binder and a conductive material onto a negative electrode current collector and drying it, or by casting the negative electrode slurry onto a separate support and then peeling the film from the support and laminating the resulting film onto a negative electrode current collector. (Separator) Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. If it is a separator that is usually used in lithium secondary batteries, it can be used without any special restrictions, and in particular, it is preferable that it has low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity. Preferably, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, can be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. can be used. In addition, a coated separator containing a ceramic component or a polymer material can be used to secure heat resistance or mechanical strength, and can be selectively used in a single-layer or multi-layer structure. (electrolyte) In addition, examples of the electrolyte used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries. Preferably, the electrolyte may include an organic solvent and a lithium salt. As the organic solvent, any solvent that can act as a medium through which ions involved in the electrochemical reaction of the battery can move may be used without particular limitation. Preferably, the organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Examples of solvents that can be used include carbonate solvents, such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents, such as ethyl alcohol and isopropyl alcohol; nitriles, such as R-CN (wherein R represents a C2 to C20 linear, branched, or cyclic hydrocarbon group, and may include a double-bonded aromatic ring or an ether bond); amides, such as dimethylformamide; dioxolanes, such as 1,3-dioxolane; and sulfolanes. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable. The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Preferably, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably in the range of 0.1 to 5.0 M, and preferably 0.1 to 3.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively. In addition to the electrolyte components, the electrolyte may further include additives for the purposes of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. For example, the additives may include haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexamethylphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxy ethanol, or aluminum trichloride, either singly or in mixtures, but are not limited thereto. The additives may be included in an amount of 0.1 to 10 wt%, preferably 0.1 to 5 wt%, based on the total weight of the electrolyte. As described above, since the lithium secondary battery according to the present invention exhibits excellent output characteristics, it is useful not only in the field of electric vehicles such as hybrid electric vehicles (HEVs), but also in the field of portable devices such as mobile phones, laptop computers, and digital cameras. Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided. The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, including power tools; electric vehicles including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems. Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. Example 1 As a particle, the average particle diameter D 50 This 9.9㎛ Li 1.0 [Ni 0.7 Co 0.1 Mn 0.2 ]O2 and mean particle size (D) as small particles 50 ) is 4㎛ Li 1.0 [Ni 0.7 Co 0.1 Mn 0.2 ]O2 was mixed in a weight ratio of 70:30 to prepare a mixed cathode active material. At this time, the large and small particles were in the form of secondary particles, and the large particles had a BET surface area of ​​5.7 m 2 / g complex transition metal precursor (Ni 0.7 Co 0.1 Mn 0.2 (OH)2) and a lithium source (Li2CO3) were mixed so that the molar ratio of Li:Ni+Co+Mn was 1.03:1, and then calcined to produce the product. A cathode material was manufactured by mixing the above mixed cathode active material and H3BO3, and then calcining at a temperature of 320°C for 6 hours to form a coating layer containing boron (B) on the surface of the cathode active material particles. Boron (B) was included at 800 ppm based on the total weight of the cathode material. Thereafter, the positive electrode material, carbon black as a conductive material, and polyvinylidene fluoride (PVDF) as a binder were mixed in a weight ratio of 96: 1: 3 in N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode slurry. The positive electrode slurry was applied to one surface of an aluminum current collector, dried at 130°C, and then rolled to prepare a positive electrode. An anode slurry was prepared by mixing artificial graphite as an anode active material, carbon black as a conductive material, and carboxymethyl cellulose (CMC) as a binder in a weight ratio of 97:1.5:1.5, and the slurry was applied to one surface of a copper current collector, dried at 110°C, and then rolled to produce an anode. An electrode assembly was manufactured by interposing a separator between the positive and negative electrodes, and then positioning the assembly inside a battery case, and then injecting an electrolyte into the case to manufacture a lithium secondary battery. The electrolyte was an electrolyte in which 1 M LiPF6 was dissolved in a mixed organic solvent of ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) in a volume ratio of 30:40:30. Examples 2-3 and Comparative Examples 1-5 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the ratio of the number of moles of lithium (Li) contained in Li2CO3 to the total number of moles of transition metals (Ni+Co+Mn, Me) in the composite transition metal precursor during the manufacture of the large particles (Li / Me) and the BET specific surface area of ​​the composite transition metal precursor were controlled as shown in Table 1 below. In addition, the average particle diameter of the particles used in the examples and comparative examples is as shown in Table 1 below. BET surface area of ​​Li / Me precursor in the production of large particles (m 2 / g) Average particle size (D50, ㎛) Example 11.035.79.9 Example 21.065.79.9 Example 31.035.69.7 Comparative Example 11.034.69.7 Comparative Example 21.056.09.9 Comparative Example 31.054.69.7 Comparative Example 41.066.09.9 Comparative Example 51.065.79.9 Experimental Example 1: Measurement of BET surface area and average crystallite size of cathode material The BET specific surface area of ​​the cathode material powders manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 was measured by the BET method, and the average crystallite size was measured by performing X-ray diffraction analysis (XRD, Bruker D8 Endeavor). At this time, the conditions for performing the BET method and X-ray diffraction analysis are the same as those described above. The measurement results are shown in Table 2 below. BET surface area of ​​anode material (m 2 / g)Average crystallite size (nm)Example 10.42163Example 20.42160Example 30.46165Comparative Example 10.37150Comparative Example 20.66152Comparative Example 30.38162Comparative Example 40.61161Comparative Example 50.43143 Experimental Example 2: Measurement of residual lithium content and cation mixing ratio After dispersing 5 g of the cathode material powder manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 in 100 ml of distilled water, the amount of residual lithium dissolved in the distilled water was measured using the pH titration method. The measured amount of residual lithium was expressed as weight% based on the total weight of the cathode material. In addition, the cation mixing ratio of the cathode materials manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 was measured through XRD analysis. The XRD analysis was performed using an X-ray diffraction analyzer (Bruker AXS D4-Endeavor XRD), using a Cu Ka light source, and under 10 kV acceleration voltage conditions. The above measurement results are shown in Table 3 below. Amount of residual lithium in the cathode material (wt%) Cation mixing ratio (at%) Example 10.29 1.5 Example 20.27 1.4 Example 30.26 1.5 Comparative Example 10.27 1.4 Comparative Example 20.33 1.4 Comparative Example 30.34 1.4 Comparative Example 40.40 1.4 Comparative Example 50.44 2.2 Experimental Example 3: Initial Resistance Measurement Each lithium secondary battery manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 was charged to 4.25 V at a constant current of 0.3 C at 25°C, and discharged to 3.0 V at a constant current of 39 mAh / g, which constituted one cycle, and three charge / discharge cycles were performed. Next, the battery was charged to 4.25 V at 0.3 C CC under constant current-constant voltage (CC-CV) charging conditions at 25 °C, then pulse discharged at 2.5 C rate under SOC 50% and 10% conditions to measure the voltage drop for 10 seconds to obtain the initial resistance value. The initial resistance values ​​are shown in Table 4 below. Experimental Example 4. Evaluation of Gas Generation Amount Each lithium secondary battery manufactured in Examples 1 to 3 and Comparative Examples 1 to 5 was charged to 4.25 V at a constant current of 0.3 C, and then charged at a constant voltage of 4.25 V until the charge current became 0.05 C (cut-off current). Then, each lithium secondary battery was stored at 60° C. for 4 weeks, and the amount of gas evolution was measured. The amount of gas generated is shown in Table 4 below. Initial Resistance (Ω)Gas Generation (㎕)SOC 50%SOC 10%Example 11.432.34216Example 21.452.37230Example 31.422.42226Comparative Example 11.422.52236Comparative Example 21.392.23352Comparative Example 31.432.43259Comparative Example 41.382.20333Comparative Example 51.512.43367 Through the above Table 4, it can be seen that in the cases of Examples 1 to 3, where the BET surface area and average crystallite size of the cathode material satisfy the range of the present invention, the amount of gas generated is less than in the cases of Comparative Examples 1 to 5, and the initial resistance value is at a similar level or smaller.

Claims

1. A cathode material including a cathode active material including lithium nickel-based oxide particles in the form of secondary particles in which a plurality of primary particles are aggregated, wherein the content of nickel among the total metals excluding lithium is 50 mol% to 90 mol%; and a coating layer formed on the surface of the lithium nickel-based oxide particles and including boron (B); The BET surface area of ​​the above cathode material is 0.41 m 2 / g to 0.59m 2 / g and, A cathode material having an average crystallite size of 155 nm or more.

2. In paragraph 1, A cathode material having an average crystallite size of 155 nm to 170 nm.

3. In paragraph 1, The above lithium nickel-based oxide particles are cathode materials represented by the following chemical formula 1: [Chemical Formula 1] Li a [Ni b Co c M 1 d M 2 e ]O2 In the above chemical formula 1, M 1 is Mn, Al or a combination of these, and M 2 is at least one selected from the group consisting of Ti, Mg, Al, Zr, Y, Ba, Ca, Sr, W, Ta, Nb, and Mo, and 0.80≤a≤1.20, 0.50≤b≤0.90, 0 <c≤0.40, 0<d≤0.40, 0≤e≤0.10이다.

4. In paragraph 1, A cathode material wherein the above boron (B) is contained in an amount of 500 ppm to 1000 ppm based on the total weight of the cathode material.

5. In paragraph 1, A cathode material having a residual lithium content of 0.2 wt% to 0.4 wt%.

6. In paragraph 1, A cathode material having a cation mixing ratio of 2.5 at% or less.

7. In paragraph 1, The above cathode material has an average particle diameter D 50 These large particles of 6㎛ to 20㎛, Average particle diameter D 50 A cathode material comprising small particles having a size of 0.1 μm to 5.5 μm.

8. In paragraph 7, A cathode material in which the above large and small particles are included in a weight ratio of 60:40 to 80:

20.

9. A cathode comprising the cathode material of claim 1.

10. A lithium secondary battery comprising the positive electrode of claim 9.