Lithium secondary battery cathode active material, manufacturing method therefor, and lithium secondary battery comprising same

Abstract

The present invention relates to a lithium secondary battery cathode active material which is in a single particle form and contains 50-70 mol% of nickel on the basis of the total number of moles of metals excluding lithium, and in which D 50 / FWHM (110) satisfies a specific range.

Description

A positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same

[0001] The present invention relates to a positive electrode active material for a lithium secondary battery, a method for manufacturing the same, and a lithium secondary battery including the same. More specifically, the invention relates to a method for manufacturing a positive electrode active material for a lithium secondary battery in the form of a single particle, a positive electrode active material manufactured therefrom, and a lithium secondary battery including the same.

[0002] This application claims priority to Korean Patent Application No. 10-2024-0190698, filed on December 19, 2024, the entire contents of which are incorporated herein by reference.

[0003] Recently, the demand for IT mobile devices, small power drive systems (e-bikes, small EVs, etc.), and Energy Storage Systems (ESS) has been increasing explosively. Consequently, the development of high-capacity and high-energy-density secondary batteries to power these devices is actively underway worldwide. To manufacture such high-capacity batteries, high-capacity cathode materials must be used.

[0004] Among existing layered cathode active materials, LiNiO2 has the highest capacity, but commercialization is difficult due to structural collapse occurring easily during charging and discharging and low thermal stability caused by oxidation state issues.

[0005] To solve this problem, other stable transition metals (Co, Mn, etc.) must be substituted at the unstable Ni sites, and for this purpose, ternary NCM systems with Co and Mn substituted have been developed.

[0006] Conventional NCM-based cathode active materials are composed of secondary particles formed by the aggregation of primary particles. However, cathode materials composed of secondary particles formed by the aggregation of primary particles ranging in size from tens of nanometers to several micrometers have a large specific surface area of ​​powder, resulting in a large surface area in contact with the electrolyte, which leads to a high potential for gas generation. Additionally, there is a problem where the lifespan characteristics deteriorate because the secondary particles break into primary particles during the electrode rolling process due to the weak strength of the secondary particles.

[0007] To solve this problem, a method has been proposed to manufacture a cathode material in the form of a single particle with 20 or fewer primary particles clustered together by maximizing the size of the primary particles, rather than in the form of a secondary particle with tens to hundreds of primary particles clustered together, and then to apply it. However, in this case, a rock salt structure is formed on the surface of the particles, which causes a problem in that the electrochemical performance of the cathode active material is degraded.

[0008] Therefore, there is a need to develop cathode active materials capable of increasing battery life stability while simultaneously exhibiting excellent electrochemical characteristics, such as charge / discharge capacity, by performing multiple analyses on single-particle cathode materials to derive appropriate physical properties.

[0009] In this embodiment, regarding a single-particle positive active material, the electrochemical properties and stability of the positive active material for a lithium secondary battery are improved when the relationship between the half-width and average particle size with respect to the (110) plane satisfies a specific range, and the positive active material for a lithium secondary battery including the same is provided.

[0010] A positive electrode active material for a lithium secondary battery according to one embodiment is a positive electrode active material for a lithium secondary battery in the form of a single particle containing 50 to 70 mol% of nickel based on the total molar amount of metal excluding lithium, and can satisfy Formula 1 below.

[0011] [Equation 1]

[0012] 24.00 ≤ D50 / FWHM(110) ≤ 30.50

[0013] In the above Equation 1, FWHM (110) is the full width at half maximum [°] of the peak on the (110) plane measured by X-ray diffraction (XRD), and D50 represents the average particle size [μm] of the positive active material.

[0014] A method for manufacturing a positive electrode active material for a lithium secondary battery according to another embodiment comprises the steps of: preparing a metal precursor containing 50 to 70 mol% of nickel based on the total molar amount of the metal; mixing the metal precursor with a lithium raw material to form a mixture; mixing the mixture with an aqueous binder to form granules; calcining the granules to form a lithium metal oxide; and crushing the lithium metal oxide at 3.3 to 4.7 bar to form a positive electrode active material for a lithium secondary battery in the form of a single particle, wherein in the granule forming step, the mixture and the aqueous binder may be mixed in a weight ratio of 85:15 to 75:25.

[0015] A positive electrode for a lithium secondary battery according to another embodiment may include a positive electrode active material according to the present invention.

[0016] A lithium secondary battery according to another embodiment may include a positive electrode according to the present invention.

[0017] According to the present embodiment, by appropriately controlling the manufacturing process of a positive electrode active material for a lithium secondary battery, a positive electrode active material can be manufactured in which a relationship consisting of half-width and average particle size for the (110) plane satisfies a specific range.

[0018] Accordingly, it is possible to realize a positive electrode active material with improved electrochemical properties, such as high stability and high capacity.

[0019] Figure 1 is an SEM image of the positive electrode active material prepared according to Example 1, magnified 3,000 times.

[0020] Figure 2 is an SEM image of the positive electrode active material prepared according to Comparative Example 1, magnified 3,000 times.

[0021] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention.

[0022] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0023] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0024] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0025] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0026] In this specification, the term “combination(s) of these” described in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expression, and means including any one or more selected from the group consisting of said components.

[0027] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0028]

[0029] Cathode active material for lithium secondary batteries

[0030] A positive electrode active material for a lithium secondary battery according to one embodiment of the present invention comprises a lithium transition metal oxide in the form of a single particle. The active material in the form of a single particle has a smaller specific surface area compared to conventional secondary particles, which reduces the amount of gas generated due to side reactions with the electrolyte. Additionally, it has a higher particle strength, which can suppress particle breakage during rolling and reduce the occurrence of cracks due to repeated charging and discharging. Accordingly, it has the advantage of superior lifespan and safety compared to secondary particles, and can achieve high energy density of the electrode.

[0031] In this specification, a single particle may include at least one of a single crystal structure consisting of a single particle and a structure in which 2 to 20 or 2 to 10 particles are aggregated, which is distinguished as a single mass when the cross-section of the powder is observed through a scanning electron microscope. This can be used to distinguish it from a positive active material particle in the form of a secondary particle formed by the aggregation of tens to hundreds of primary particles that were conventionally used.

[0032] In addition, “secondary particles” refers to aggregates formed by the aggregation of tens to hundreds of primary particles through physical or chemical bonding between primary particles without any intentional aggregation or assembly process of the primary particles, i.e., secondary structures.

[0033] In addition, “primary particle” refers to the smallest particle unit that is distinguished as a single mass when the cross-section of the positive active material is observed through a scanning electron microscope (SEM), and it may consist of a single crystal grain or multiple crystal grains.

[0034] In addition, “grain” refers to a distinct region in which atoms within a primary particle form a lattice structure in a specific direction.

[0035]

[0036] In addition, to increase the energy density of the anode to which the single-particle anode active material is applied, the average particle size (D50) of the single particles is generally grown until it reaches a size of several micrometers.

[0037] However, if grain growth is excessive, there is a problem with output characteristics degrading according to capacity and C-rate, and if there are many underdeveloped particles, there may be a problem with reduced charge / discharge lifespan.

[0038] Accordingly, the calcination process conditions during the manufacture of the lithium metal oxide in the cathode active material according to the present invention are precisely controlled. As a result, the particle growth of the lithium metal oxide is effectively achieved, while defects in the layered crystal structure can be reduced. Furthermore, the lithium deficiency phenomenon on the surface of the lithium metal oxide is suppressed, and the residual lithium content remaining on the surface of the lithium metal oxide can be reduced. In addition, while ensuring a sufficient average particle size (D50) of the lithium metal oxide, excessive growth of the crystal grain size within the lithium metal oxide is suppressed, thereby ensuring a stable crystal structure. Accordingly, the capacity characteristics, high-temperature life characteristics, high-energy electrode density, and safety of the battery can be desirablely realized simultaneously.

[0039] The calcination process conditions will be explained in more detail in the method for manufacturing the positive electrode active material described later, and the specific characteristics and physical properties of the positive electrode active material according to the present invention will be explained in more detail below.

[0040] A positive electrode active material for a lithium secondary battery according to one embodiment may be a positive electrode active material for a lithium secondary battery that satisfies Formula 1 below.

[0041] [Equation 1]

[0042] 24.00 ≤ D50 / FWHM(110) ≤ 30.50

[0043] In the above Equation 1, FWHM (110) is the full width at half maximum [°] of the peak on the (110) plane measured by X-ray diffraction (XRD), and D50 represents the average particle size [μm] of the positive active material.

[0044] Specifically, D50 / FWHM (110) may be 24.00 to 30.50 μm / °, 25.00 to 30.40 μm / °, 26.00 to 30.30 μm / °, or 26.50 to 30.20 μm / °.

[0045] Since the structural stability of the positive electrode active material may vary depending on the nickel content and particle shape, the above range may be a preferred range for a single-particle positive electrode active material for a lithium secondary battery containing 50 to 70 mol% of nickel based on the total molar amount of metal excluding lithium.

[0046] If the above range is satisfied, excellent charge / discharge capacity and excellent high-temperature life characteristics can be achieved simultaneously. If it falls below the above range, high-temperature life characteristics may deteriorate, and if it exceeds the above range, charge / discharge capacity may decrease.

[0047] More specifically, D50 / FWHM (110) may be limited to a lower limit of 27.00 μm / ° or more, 27.50 μm / ° or more, or 28.00 μm / ° or more in addition to the aforementioned range, and if the range is satisfied, the high temperature life characteristics may be better.

[0048] For reference, it is difficult to achieve the excellent effect according to the present invention if only one of D50 or FWHM (110) satisfies the desirable range, and the excellent effect is confirmed only when D50 / FWHM (110) satisfies the desirable range according to the present invention.

[0049]

[0050] The above FWHM (110) may be 0.1050 to 0.1250˚, and more specifically, 0.1070 to 0.1240˚, 0.1090 to 0.1230˚, 0.1100 to 0.1220˚, 0.1115 to 0.1210˚, or 0.1130 to 0.1200˚.

[0051] (110) If the half-width of the peak on the plane is too small, the particle size of the single particle becomes too large, and the capacity characteristics of the battery may decrease due to the decrease in diffusion rate. (110) If the half-width of the peak on the plane is too large, the lithium loss on the surface of the secondary particle becomes severe, and the capacity characteristics of the battery may decrease.

[0052] In addition, the above FWHM (110) may be 0.1140˚ or greater or 0.1145˚ or greater, and if this range is satisfied, the charge / discharge capacity characteristics may be superior.

[0053] The positive electrode active material according to the present invention may have an average particle size (D50) of 2.80 to 3.50 μm, and more specifically, 2.95 to 3.47 μm or 3.10 to 3.45 μm. If the average particle size (D50) is too small, the density of the positive electrode composite decreases, making it difficult to achieve high energy density of the positive electrode. If the average particle size (D50) is too large, the capacity characteristics of the positive electrode active material may decrease. Therefore, when the average particle size (D50) satisfies the above range, the energy density of the positive electrode can be preferably achieved.

[0054] In this specification, the average particle size (D50) may be defined as the particle size corresponding to 50% of the volume accumulation in the particle size distribution curve. The average particle size (D50) may be measured, for example, using a laser diffraction method.

[0055]

[0056] The ratio c / a of the c-axis lattice constant to the a-axis lattice constant of the positive electrode active material according to one embodiment may be 4.92 or less, and more specifically, may be 4.90 to 4.92 or 4.9150 to 4.9185.

[0057] In this specification, “c-axis lattice constant” and “a-axis lattice constant” may refer to the length of a lattice parameter representing one side of a unit lattice within a crystal structure derived from XRD measurements of the positive electrode active material. Specifically, the positive electrode active material according to one embodiment of the present invention may have a layered crystal structure (R-3m), and may refer to the lengths of the side (a) existing in the x and y axes and the side (c) existing in the z axis in such a structure. More specifically, the “c-axis lattice constant or a-axis lattice constant” can be derived from the 2theta values ​​of the (003) peak and the (110) peak of the XRD data, and can be quantitatively calculated through the Bragg equation and crystal structure information.

[0058]

[0059]

[0060] If it falls below the aforementioned range, the mobility of lithium ions in the cathode active material may be poor, and lifespan characteristics may be degraded. On the other hand, if it exceeds the aforementioned range, the insertion of lithium into the cathode active material may be insufficient, resulting in a low capacity.

[0061] The above-described positive active material may have a c-axis lattice constant of 14.1060 Å or less, and more specifically, 14.0900 to 14.1050 Å. Additionally, the above-described positive active material may have an a-axis lattice constant of 2.86830 Å or less, and more specifically, 2.8675 to 2.86825 Å. Accordingly, the phenomenon of lithium deficiency on the surface of lithium metal oxide secondary particles can be reduced, thereby improving capacity characteristics. Specifically, as mentioned above, if the calcination process conditions are not properly controlled during the manufacture of single particles, lithium becomes deficient on the surface of the lithium metal oxide secondary particles; in this case, the repulsive force between oxygen layers becomes dominant, which may increase the c-axis or a-axis lattice constant. On the other hand, in the positive active material according to the present invention, the phenomenon of lithium deficiency on the surface is suppressed by controlling the calcination process, and accordingly, the c-axis or a-axis lattice constant of the lithium metal oxide can be obtained to be appropriately small, and capacity characteristics can be improved.

[0062]

[0063] According to one embodiment, the positive active material may have a fine amount of less than 1.0 μm of 0.50 to 2.50 vol%, more specifically 0.60 to 2.00 vol%. The fine amount of less than 1.0 μm may refer to the ratio of fine particle size distribution of less than 1.0 μm in the volume-based particle size distribution curve of the positive active material.

[0064] By satisfying the aforementioned range, gas generation caused by fine particles can be prevented, thereby maximizing the safety of the battery, and by securing an appropriate specific surface area, excellent charge / discharge capacity characteristics can be exhibited.

[0065]

[0066] Meanwhile, the above-mentioned positive active material has a BET specific surface area of ​​0.65 to 0.77 m² 2 / g may be possible. The inventors have found that, in the case of the anode active material according to the present invention in which crystallinity is sufficiently recovered as the calcination process is controlled, the specific surface area is 0.65 m² 2 It was confirmed that a large amount is obtained when the value is greater than / g. This appears to be because lithium metal oxides with poor crystallinity have a strong tendency to aggregate, which reduces grinding efficiency during the disintegration process and results in a small specific surface area. If the specific surface area of ​​the cathode active material is excessively large beyond the aforementioned range, the high-temperature lifespan characteristics may appear inferior.

[0067] In this specification, the specific surface area of ​​the active material can be measured using the N2 absorption BET method (Surface area and Porosity analyzer) (Micromeritics, ASAP2020) for the active material powder.

[0068]

[0069] Meanwhile, the lithium metal oxide may have a residual lithium content of 0.2 wt% or less, and more specifically, 0.18 wt% or 0.17 wt% or less. Residual lithium refers to lithium byproducts that remain on the surface of the lithium metal oxide without forming a crystal structure, and may include LiOH and / or Li2CO3. Residual lithium can impair the safety of the battery by promoting gas generation through side reactions with the electrolyte. In the lithium metal oxide according to the present invention, the residual lithium content is reduced by controlling the calcination process conditions, thereby improving the stability of battery manufacturing.

[0070]

[0071] Meanwhile, the positive electrode active material for a lithium secondary battery according to the present invention may contain 50 to 70 mol%, more specifically 55 to 65 mol%, of nickel (Ni) based on the total molar amount of transition metal.

[0072] The structural stability of the cathode active material may vary depending on the nickel content. If the nickel content is too high, there may be thermal propagation issues, and the cost may increase. However, if the nickel content is too low, the capacity may become too low. Therefore, by including nickel within the aforementioned range, the cathode active material according to the present invention can achieve an appropriate capacity while ensuring excellent thermal stability and reducing manufacturing costs.

[0073] More specifically, it can be represented by the following chemical formula 1.

[0074] [Chemical Formula 1]

[0075] Li a [Ni x Co y Mn z M w ]O2

[0076] In the above chemical formula 1, 0.8≤a≤1.2, 0.5≤x≤0.7, 0.05≤y≤0.2, 0≤z≤0.4, 0≤w<0.03, x+y+z+w=1, and M is Zr, Y, B, Al, Mg, Ti, Nb, W, Sc, Si, V, Fe, Y, Mo, Ce, Hf, Ta, La, Sr or a combination thereof.

[0077] In the positive electrode active material of Chemical Formula 1 above, lithium may be included in an amount corresponding to a, i.e., 0.8 ≤ a ≤ 1.2. If a is too small, the capacity may decrease, and if a is too large, the strength of the calcined positive electrode active material may increase, making it difficult to grind, and the amount of gas generated may increase due to an increase in lithium by-products. Considering the effect of improving the capacity characteristics of the positive electrode active material by controlling the lithium content and the balance of sinterability during the manufacture of the active material, the lithium may more preferably be included in an amount of 0.9 ≤ a ≤ 1.1.

[0078] In the positive electrode active material of Chemical Formula 1 above, nickel may be included in an amount corresponding to x, i.e., 0.5≤x≤0.7. As previously mentioned, if the nickel content is too low, it may be difficult to achieve high capacity of the battery, and if the nickel content is too high, the battery life and thermal safety may decrease due to reduced structural stability of the active material, and manufacturing costs may increase.

[0079] In the positive electrode active material of Chemical Formula 1 above, the content of cobalt corresponding to y may be 0.05 ≤ y ≤ 0.2. If the cobalt content is too low, it may be difficult to simultaneously achieve sufficient rate characteristics and high powder density of the active material. If the cobalt content is too high, the cost of raw materials increases overall and the reversible capacity may decrease.

[0080] In the positive active material of Chemical Formula 1 above, manganese may be included in an amount corresponding to z, i.e., 0≤z≤0.4 or 0.1≤z≤0.4. If the manganese content is too low, the production cost may increase and the stability of the positive active material may decrease. If the manganese content is too high, the capacity and output characteristics of the battery may decrease.

[0081]

[0082] Method for manufacturing a positive electrode active material for a lithium secondary battery

[0083] The XRD properties and average particle size (D50) range of the anode active material according to one embodiment of the present invention mentioned above can be obtained by controlling the calcination process, and a method for manufacturing an anode active material according to another embodiment of the present invention will be described below.

[0084] Another embodiment of the present invention comprises the steps of: preparing a metal precursor containing 50 to 70 mol% of nickel based on the total molar amount of the metal; mixing the metal precursor with a lithium raw material to form a mixture; mixing the mixture with an aqueous binder to form granules; calcining the granules to form a lithium metal oxide; and dissolving the lithium metal oxide at 3.3 to 4.7 bar to form a single-particle positive electrode active material for a lithium secondary battery.

[0085] A method for manufacturing a positive electrode active material for a lithium secondary battery is provided, wherein in the granule forming step, the mixture and the water-based binder are mixed in a weight ratio of 85:15 to 75:25.

[0086] Hereinafter, a method for manufacturing a positive electrode active material for a lithium secondary battery according to another embodiment of the present invention will be described in detail step by step.

[0087]

[0088] First, a metal precursor containing 50 to 70 mol% of nickel based on the total molar amount of the metal is prepared.

[0089] The above transition metal precursor may be a transition metal hydroxide.

[0090] The above transition metal hydroxide may be prepared by co-precipitating a transition metal-containing solution containing a nickel raw material and optionally a cobalt raw material or a manganese raw material by adding a complexing agent-containing solution and a pH adjusting agent-containing solution to the solution.

[0091] The above nickel raw material is not particularly limited as long as it is used in the industry for manufacturing a cathode active material precursor. For example, the above nickel raw material may be a nickel-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically, it may be NiSO4, NiSO4·6H2O, Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, nickel fatty acid salt, nickel halide, or a combination thereof, but is not limited thereto.

[0092] The above-mentioned cobalt raw material is not particularly limited as long as it is used in the industry for the manufacture of cathode active material precursors. For example, the above-mentioned cobalt raw material may be a cobalt-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically, CoSO₄ 4, It may be CoSO4·7H2O, Co(OH)2, CoOOH, Co(OCOCH3)2·4H2O, Co(NO3)2·6H2O, or a combination thereof, but is not limited thereto.

[0093] The above manganese raw material is not particularly limited as long as it is used in the industry for the manufacture of cathode active material precursors. For example, the above manganese raw material may be a manganese-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof. Specifically, it may be a manganese salt such as MnSO4, MnCO3, Mn(NO3)2, manganese acetate, manganese dicarboxylate, manganese citrate, and manganese fatty acid, manganese oxide such as Mn2O3, MnO2, and Mn3O4, oxyhydroxide, manganese chloride, or a combination thereof, but is not limited thereto.

[0094] The above transition metal-containing solution may be prepared by adding a nickel raw material and optionally a cobalt raw material or a manganese raw material to a solvent, specifically water, or a mixture of water and an organic solvent that can be uniformly mixed with water (e.g., alcohol).

[0095] The above-mentioned complexing agent-containing solution performs the role of forming a complex, and may include, for example, NH3, NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, NH4CO3, or a combination thereof as the complexing agent, but is not limited thereto. Meanwhile, the above-mentioned complexing agent-containing solution may be used in the form of an aqueous solution, and in this case, water or a mixture of water and an organic solvent that is uniformly miscible with water (e.g., alcohol, etc.) may be used as the solvent.

[0096] The above pH-adjusting solution acts as a precipitating agent or a pH adjuster and may include alkali compounds such as hydroxides of alkali metals or alkaline earth metals like NaOH, KOH, or Ca(OH)2, their hydrates, or combinations thereof. Meanwhile, the above pH-adjusting solution may also be used in the form of an aqueous solution, in which case water or a mixture of water and an organic solvent that is uniformly miscible with water (e.g., alcohol) may be used as the solvent. In this case, the above pH-adjusting solution may be added in an amount such that the pH of the reaction solution becomes 11 to 13.

[0097] The above co-precipitation reaction can be carried out under an inert atmosphere such as nitrogen or argon, at a temperature of 30 to 70°C, and at a pH of 11 to 13.

[0098] By the above process, particles of nickel-cobalt-manganese (-doping element) hydroxide are generated and precipitated in the reaction solution. The precipitated precursor particles can be separated by conventional methods, washed, and dried to obtain a precursor. The precursor may be a secondary particle formed by the aggregation of primary particles.

[0099] At this time, the molar ratio of nickel, cobalt, and manganese in the precursor can be controlled by adjusting the concentrations of the nickel raw material, cobalt raw material, and manganese raw material.

[0100] Accordingly, the nickel content in the transition metal precursor may be 50 to 70 mol% based on the total molar amount of the transition metal, and more specifically, 55 to 65 mol%. The technical significance of controlling the nickel content in the transition metal precursor is as described above and is therefore omitted.

[0101]

[0102] Next, the above metal precursor and lithium raw material are mixed to form a mixture.

[0103] The above lithium raw material may be a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, and is not particularly limited as long as it is soluble in water. Specifically, the above lithium raw material may be Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, Li3C6H5O7, or a combination thereof, but is not limited thereto.

[0104]

[0105] Next, the above mixture is mixed with a water-based binder to form granules.

[0106] The above mixture and the water-based binder may be mixed in a weight ratio of 85:15 to 75:25, more specifically in a weight ratio of 82.5:17.5 to 77.5:22.5. Granules may be formed when the weight ratio range is satisfied. If the water-based binder is mixed in a smaller amount than the aforementioned range, it is difficult to form granules, and if it is mixed in an excessive amount than the aforementioned range, the aggregation of the granules becomes severe and more energy may be consumed for drying.

[0107] At this time, the above-mentioned water-based binder is not particularly limited to water alone, or to 0~1 wt% of polymers such as PVA, PMMA, which are easily soluble in water, do not generate vapor pressure during heat treatment, and are easily thermally decomposed.

[0108] More specifically, granules can be formed using a rotor, with a preferred rotation speed of 700 to 800 rpm and a time of 5 to 20 minutes. If the above range is not satisfied, spherical granules may not be formed in a size suitable for firing.

[0109] The apparent density of the properly formed granules is 1.2 or higher, more specifically 1.2 to 1.5 g / cm³ 2 It may be possible. When the aforementioned range is satisfied, the sintering described below is carried out smoothly, allowing for the manufacture of a battery exhibiting excellent electrochemical characteristics.

[0110] In this case, apparent density may refer to the density measured including internal voids and empty spaces within the particles, and can be calculated as the mass of powder per unit volume when the granules are placed in a certain container.

[0111]

[0112] Next, the granules are calcined to form lithium metal oxide.

[0113] The above firing temperature may be 955 to 985°C or 957 to 983°C.

[0114] The above firing time may be 5 to 12 hours or 7 to 11 hours.

[0115] The above-mentioned firing atmosphere may be 90 to 100 vol% oxygen atmosphere or 95 to 100 vol% oxygen atmosphere. In this case, the remainder other than oxygen may be air.

[0116] When the specific sintering profile, such as sintering temperature, time, and atmosphere, satisfies the above range, the effect of grain growth of the lithium metal oxide, the effect of suppressing the lithium deficiency phenomenon in the surface portion within the bulk portion of the lithium metal oxide, the effect of enhancing crystallinity, and the effect of reducing residual lithium can be more preferably realized. Accordingly, the XRD properties of the cathode active material and the average particle size (D50) range can be appropriately realized within the range according to the present invention.

[0117]

[0118] Next, the lithium metal oxide is broken down to form a single-particle positive electrode active material.

[0119] The above crushing can be performed by methods commonly practiced in the industry, for example, using rotor mills, jet mills, ball mills, fin mills, bead mills, or roll mill equipment, but in particular, it can be performed using a jet mill, more specifically, an air jet mill using compressed air. At this time, the crushing pressure can be 3.3 to 4.7 bar, more specifically 3.4 bar or higher, 3.5 bar or higher, 3.6 bar or higher, or 3.7 bar or higher, or 4.6 bar or lower, 4.5 bar or lower, 4.4 bar or lower, or 4.3 bar or lower. More specifically, it can be performed at a crushing pressure of 3.5 to 4.5 bar or 3.8 to 4.2 bar. The above disintegration can be performed by controlling the grinding pressure differently according to the cohesive force between single particles depending on the calcination temperature or time during the calcination, but when performed within the above range, the generation of fine particles due to unnecessary particle breakage is suppressed, thereby suppressing side reactions with the electrolyte during operation when the electrode containing the above positive active material is included in a secondary battery, and separation between sufficiently grown particles can be performed, thereby realizing the stability of the positive active material in the desired single particle form.

[0120]

[0121] Through the above series of manufacturing methods, a lithium metal oxide in the form of a single particle according to the present invention can be formed, and the obtained positive electrode active material can be easily obtained with XRD properties and an average particle size (D50) range according to the present invention.

[0122]

[0123] anode

[0124] In another embodiment of the present invention, a positive electrode is provided comprising a current collector and a positive electrode active material layer located on one surface of the current collector and comprising a positive electrode active material manufactured according to the above embodiment.

[0125] The characteristics of the positive active material constituting the above positive active material layer are the same as those previously described. Therefore, a detailed description of the positive active material will be omitted.

[0126] The above current collector may be, for example, made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treated with carbon, nickel, titanium, silver, etc.

[0127] Meanwhile, the above positive active material layer may include a binder and a conductive material.

[0128] At this time, the binder serves to improve adhesion between positive active material particles and adhesion between the positive active material and the positive 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. One of these alone or a mixture of two or more may be used, but is not limited thereto. The binder may be included in an amount of 1 to 30 weight% based on the total weight of the positive active material layer.

[0129] In addition, the 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, and carbon fibers; 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 may be used, but is not limited thereto. The conductive material may typically be included in an amount of 1 to 30 weight% relative to the total weight of the positive electrode active material layer.

[0130] Except for being manufactured to fall within the above range, the above anode may be manufactured according to a conventional anode manufacturing method.

[0131] Specifically, the anode may be manufactured by applying a composition for forming an anode active material layer, which optionally includes a binder, a conductive material, or a solvent as needed, onto an anode current collector, followed by drying and rolling. At this time, the types and contents of the anode active material, binder, and conductive material are as described above.

[0132] The above solvent may be a solvent commonly used in the relevant technical field, such as dimethylsulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these alone or a mixture of two or more may be used. The amount of the above solvent used is sufficient if it has a viscosity that dissolves or disperses the anode active material, conductive material, and binder, taking into account the coating thickness of the slurry and the manufacturing yield, and subsequently provides excellent thickness uniformity when coated for anode manufacturing.

[0133] Alternatively, the anode may be manufactured by casting a composition for forming an anode active material layer onto a separate support, and then laminating the film obtained by peeling off from the support onto an anode current collector.

[0134]

[0135] lithium secondary battery

[0136] In another embodiment, a lithium secondary battery including the anode is provided.

[0137] The above lithium secondary battery may specifically include a positive electrode, a negative electrode positioned opposite to the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode is as described above. Additionally, the lithium secondary battery may optionally further include a battery container housing an electrode assembly comprising the positive electrode, the negative electrode, and the separator, and a sealing member for sealing the battery container.

[0138] In the above lithium secondary battery, the negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0139] 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.

[0140] The above-mentioned cathode active material layer may optionally include a binder and a conductive material together with the cathode active material. The above-mentioned cathode active material layer may be manufactured, as an example, by applying a composition for forming a cathode active material layer, comprising a cathode active material and optionally a binder and a conductive material, onto a cathode current collector and drying it, or by casting the composition for forming a cathode onto a separate support and then laminating the film obtained by peeling it off from the support onto a cathode current collector.

[0141] 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; metal oxides capable of doping and dedoping lithium, such as SiOβ (0 ≤ β ≤ 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the above-mentioned metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the above-mentioned negative electrode active material. Furthermore, the carbon material 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.

[0142] The binder and conductive material mentioned above may be the same as those previously described in the anode.

[0143] Next, depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. As such a separator, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used, and a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may also be used.

[0144] In addition, regarding the above lithium secondary battery, the electrolyte may include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which are usable when manufacturing a lithium secondary battery, but is not limited to these.

[0145] Specifically, the organic liquid electrolyte may include an organic solvent and a lithium salt.

[0146] The above organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; and aromatic hydrocarbon-based solvents such as benzene and fluorobenzene. Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having C2 to C20 structures and may include a double bond, a directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, a carbonate-based solvent is preferred, 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-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.In this case, using a mixture of cyclic carbonate and chain carbonate in a volume ratio of about 1:1 to about 1:9 can result in excellent performance of the electrolyte.

[0147] The above lithium salt can be used without special restrictions 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 2.0 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.

[0148] As described above, since the lithium secondary battery including the positive electrode according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it is useful in portable devices such as mobile phones, laptop computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs).

[0149]

[0150] Preferred embodiments and comparative examples of the present invention are described below. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0151]

[0152] Preparation of positive electrode active material

[0153] Example 1

[0154] Ni with a D50 of 3.5 μm so that the molar ratio of lithium to the transition metal (Li / M) of the (mixed) precursor is 1.050.60 Co 0.10 Mn 0.30 A mixture was formed by mechanically mixing a (OH)2 hydroxide precursor with Li2CO3.

[0155] (Granule Preparation) The above mixture was placed into an intensive mixer, and water was added at a weight ratio of 20 wt% to the mixture and binder. Granules were then prepared by adjusting the rotor's rotation speed and time. The shape of the prepared granules was mostly spherical, and the apparent density of the granules was 1.2 to 1.5 g / cm³. 2 It was measured as.

[0156] The size of the manufactured granules was measured using image analysis equipment, and the granule sizes were widely distributed in the range of diameter from 1.0 to 10.0 mm.

[0157] After (calcination), the mixture was heated to 970°C for 3 hours under an oxygen (O2) atmosphere with an oxygen partial pressure of 100%, and then calcined at a constant temperature of 970°C for 9 hours. Afterward, it was naturally cooled for 4 hours to produce a single-particle aggregate.

[0158] (Disintegration) The manufactured single-particle aggregates were first coarsely ground, and then disintegrated using a jet mill to form single-particle lithium transition metal oxides.

[0159] The composition of the finally obtained lithium transition metal oxide is LiNi 0.60 Co 0.10 Mn 0.30 It was O2.

[0160]

[0161] Examples 2, 3, and Comparative Examples 1 to 5

[0162] Granules were manufactured by determining optimal conditions within the range of a water-based binder content of 15–25%, a rotor rotation speed of 500–2000 rpm, and a rotor rotation time of 5–25 minutes. The cathode active material was prepared in the same manner as in Example 1, except that the calcination temperature profile, air supply conditions, and disintegration conditions were adjusted as shown in Table 1 below. At this time, oxygen or CFA (CO2-Free Air) was mixed and used for air supply to control the calcination atmosphere.

[0163]

[0164] Calcination Conditions Disintegration Conditions Temperature [°C] Atmosphere [vol%] Supply Pressure [bar] Example 1970O21004 Example 2960O21004 Example 3980O21004 Comparative Example 1950O21004 Comparative Example 2990O21004 Comparative Example 3970O2804 Comparative Example 4970O21003 Comparative Example 5970O21005

[0165] Experimental Example 1: Evaluation of SEM Images of Anode Active Material

[0166] Scanning electron microscope (SEM) images of the positive electrode active material prepared according to Example 1 and Comparative Example 1 were observed and are shown in Figures 1 and 2, respectively.

[0167] Referring to Figures 1 and 2, the positive active materials prepared according to Example 1 and Comparative Example 1 have a single-particle form, but it was confirmed that the positive active material according to Example 1 has a higher degree of single-particle formation.

[0168] Specifically, Example 1 consisted mostly of a single primary particle and a first aggregate of 2 to 5 primary particles. On the other hand, Comparative Example 1 consisted mostly of a second aggregate of 6 to 20 aggregated particles, with the aforementioned single particle and first aggregate present in small numbers.

[0169]

[0170] Experimental Example 2: Evaluation of Physical Properties of Anode Active Material

[0171] The physical properties of the cathode active materials prepared according to Examples 1 to 3 and Comparative Examples 1 to 5 were evaluated using the method described below. The results are shown in Table 2 below.

[0172]

[0173] (1) Evaluation of average particle size (D50)

[0174] For the active material powder, the particle size corresponding to 50% of the volume accumulation was measured using the laser diffraction method.

[0175]

[0176] (2) 110-page half-width evaluation

[0177] XRD data of the active material was measured using Rikaku's Smartlab XRD (X-ray diffraction) equipment and the pattern was analyzed to evaluate the full width at half maximum (FWHM (110)) of the (110) plane. FWHM (110) represents the width (FWHM) at half the height of the intensity of the peak (peak where 2θ is approximately 66°) corresponding to the (110) plane.

[0178]

[0179] (3) Evaluation of c-axis lattice constant and a-axis lattice constant

[0180] XRD data of the active material was measured using Rikaku's Smartlab XRD equipment. From the d-spacing of the (003) plane and the (110) plane and the crystal structure information, the c-axis lattice constant (Lc) and the a-axis lattice constant (La) were evaluated.

[0181]

[0182] (4) Evaluation of fine powder content

[0183] For each manufactured cathode active material, the particle size distribution was measured using a particle size analyzer, and the ratio of fine particles (particles with a diameter of less than 1 μm) was measured.

[0184] Specifically, 61 mL of 10 wt% (NaPO3) as a dispersant was mixed with 500 mL of water, and the disintegrated cathode active material was added to the mixture and sonicated for about 1 minute. Afterwards, the fine powder content was evaluated by analyzing the particle size using a Malvern (MS3000) instrument and measuring the volume % of fine powder with a particle size of less than 1.0 μm.

[0185]

[0186] (5) BET specific surface area evaluation

[0187] The specific surface area of ​​the active material powder was measured using the BET method (Surface area and Porosity analyzer) (Micromeritics, ASAP2020).

[0188]

[0189] (6) Evaluation of residual lithium

[0190] After adding distilled water to the cathode active material, residual lithium was extracted using a stirrer, and the cathode active material powder and extract were separated using a filter. Subsequently, the residual lithium was evaluated by measuring the extract through neutralization titration using a Mettler Toledo potentiometric titrator.

[0191]

[0192] FWHM(110)(˚)D50(μm)D50 / FWHM(110)(μm / ˚)La(Å)Lc(Å)Lc / La Differential Ratio (vol%) Specific Surface Area (m² 2 / g) Residual Lithium (wt%) LiOH Li2CO3 Example 1 0.1 150 3.28 28.5 22.86 79 21 4.1 00 33 4.9 16 61.1 20.7 11 30.0 8 0.0 8 Example 2 0.1 180 3.1 62 6.7 82.86 81 01 4.1 04 53 4.9 17 71.6 9 0.7 55 8 0.0 8 0.0 9 Example 3 0.1 135 3.4 23 0.1 32.86 79 41 4.1 02 43 4.9 17 30.6 8 0.6 7 050.070.09 Comparative Example 10.15112.6817.742.8683814.113834.92053.250.83450.080.10 Comparative Example 20.12683.9230.912.8687414.107564.91770.000.61370.110.18 Comparative Example 30.15183.5923.652.8694014.109724.91730.400.78560.100.58 Comparative Example 40.11473.8333.392.8680014.105914.91841.280.63140.080.10Comparative Example 50.14213.3223.362.8683814.109394.91891.840.81880.060.19

[0193] Experimental Example 3: Evaluation of Electrochemical Characteristics of Lithium Secondary Battery

[0194] To evaluate the physical properties and electrochemistry of the positive electrode active materials according to the examples and comparative examples, coin cells were manufactured as follows.

[0195] Specifically, the slurry for manufacturing the electrode plate was prepared by mixing the positive active material, conductive material (carbon black, Denka black), and binder (PVDF, KF1100) according to the above examples and comparative examples in a ratio of 96.5 : 1.5 : 2 wt%, and NMP (N-Methyl-2-pyrrolidone) was added to adjust the viscosity so that the solid content was approximately 30%. The prepared slurry was coated onto a 20 µm thick Al foil using a doctor blade and then dry-rolled. The electrode loading amount was 15.4 mg / cm². 2 It was, and the rolled density (25℃, 20kN) was 3.6 g / cm³ 3 It was.

[0196] A coin cell was manufactured using an electrolyte of 1M LiPF6 in EC:DMC:EMC=3:4:3 (vol%) with 3.0 vol% of VC added relative to the total amount of the electrolyte, a PP separator, and a lithium anode (200 μm, Honzo metal).

[0197]

[0198] (1) Initial dose evaluation

[0199] After fabricating a lithium secondary battery half cell, it was aged at 25°C for 12 hours, and then a charge-discharge test was performed at 25°C. To evaluate the initial capacity, 200 mAh / g was set as the reference capacity at 1C, and the battery was charged to 4.4V with a constant current of 0.1C. Then, the voltage was switched to a constant voltage, and charging continued until the terminal current reached 0.05C. After a 10-minute rest time following charging, the battery was discharged until it reached 2.5V with a constant current of 0.1C and a reference capacity of 200 mAh / g.

[0200]

[0201] (2) High temperature life evaluation

[0202] High-temperature life characteristics were tested by performing 50 charge-discharge cycles at high temperature (45°C) under charge-discharge conditions of 0.5C constant voltage charging and 1.0C constant current discharging, and the capacity retention rate of the 50th cycle was measured relative to the first cycle.

[0203]

[0204] 1 st Charging Capacity (mAh / g) 1st Discharge Capacity (mAh / g) Capacity Retention Rate (%) Example 1 217.3 196.1 95.8 Example 2 217.8 196.5 95.4 Example 3 216.5 195.4 96.0 Comparative Example 1 218.2 197.9 94.2 Comparative Example 2 215.8 192.9 96.1 Comparative Example 3 218.4 198.5 93.2 Comparative Example 4 216.8 194.2 95.8 Comparative Example 5 216.4 196.6 94.4

[0205] Referring to Tables 2 and 3, in the case of Examples 1 to 3 in which the calcination process conditions were appropriately controlled according to the present invention, it was confirmed that D50 / FWHM (110) was realized within a desirable range, and that all XRD-related physical properties and average particle size (D50) were appropriately realized within the range according to the present invention, and that residual lithium was reduced, thereby predicting an improvement in the safety of the battery. In addition, in this case, it was confirmed that the initial charge capacity and discharge capacity characteristics of the lithium secondary battery were excellently realized, and at the same time, the high-temperature life characteristics were excellently realized.

[0206] On the other hand, in the case of Comparative Examples 1 to 3, D50 / FWHM (110) was outside the range according to the present invention, and a high residual lithium was obtained, so a decrease in the safety of the battery was predicted. In addition, in this case, it was confirmed that the initial charge capacity and discharge capacity characteristics and high-temperature life characteristics of the battery deteriorated compared to the examples.

[0207] Meanwhile, in the case of Comparative Examples 4 and 5, D50 and FWHM (110) were each at a level similar to that of the example, but D50 / FWHM (110) was outside the range according to the present invention, and a high residual lithium was obtained, so a decrease in the safety of the battery was predicted. In addition, in this case, it was confirmed that the initial charge capacity and discharge capacity characteristics and high-temperature life characteristics of the battery deteriorated compared to the example.

[0208]

[0209] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

[0210] Therefore, the substantive scope of the present invention shall be defined by the appended claims and their equivalents.

Claims

1. A positive electrode active material for a lithium secondary battery in the form of a single particle containing 50 to 70 mol% of nickel based on the total molar amount of metals excluding lithium, wherein That which satisfies Equation 1 below, Cathode active material for lithium secondary batteries: [Equation 1] 24.00 ≤ D50 / FWHM(110) ≤ 30.50 In the above Equation 1, FWHM (110) is the full width at half maximum [°] of the peak for the (110) plane measured by X-ray diffraction (XRD), and D50 refers to the average particle size [μm] of the positive electrode active material.

2. In Paragraph 1, A positive electrode active material for a lithium secondary battery having a FWHM (110) of 0.1050 to 0.1250˚.

3. In Paragraph 1, A positive electrode active material for a lithium secondary battery having a D50 of 2.80 to 3.50 μm.

4. In Paragraph 1, The ratio c / a of the c-axis lattice constant to the a-axis lattice constant of the above positive active material is 4.92 or less, Cathode active material for lithium secondary batteries.

5. In Paragraph 1, A positive electrode active material for a lithium secondary battery having a c-axis lattice constant of 14.1060 Å or less Cathode active material for lithium secondary batteries.

6. In Paragraph 1, A positive electrode active material for a lithium secondary battery having an a-axis lattice constant of 2.86830 Å or less.

7. In Paragraph 1, A positive electrode active material for a lithium secondary battery having a fine amount of less than 1.0 μm of the above positive electrode active material of 0.50 to 2.50 vol%.

8. In Paragraph 1, The BET specific surface area of ​​the above positive active material is 0.65 to 0.77 m² 2 Cathode active material for lithium secondary batteries in g.

9. In Paragraph 1, The above positive active material is a positive active material for a lithium secondary battery represented by the following chemical formula 1: [Chemical Formula 1] Li a [Ni x Co y Mr z M w ]O2 In the above chemical formula 1, 0.8≤a≤1.2, 0.5≤x≤0.7, 0.05≤y≤0.2, 0≤z≤0.4, 0≤w≤0.2, x+y+z+w=1, and M is Zr, Al, B, Y, Mg, Ti, Nb, W, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, Ir, or a combination thereof.

10. A step of preparing a metal precursor containing 50 to 70 mol% of nickel based on the total molar amount of the metal; A step of forming a mixture by mixing the above metal precursor and lithium raw material; A step of mixing the above mixture with a water-based binder to form granules; A step of forming lithium metal oxide by calcining the above granules; and The method includes the step of crushing the lithium metal oxide at 3.3 to 4.7 bar to form a single-particle positive electrode active material for a lithium secondary battery, In the granule forming step above, the mixture and the water-based binder are mixed in a weight ratio of 85:15 to 75:25, Method for manufacturing a positive electrode active material for a lithium secondary battery.

11. In Paragraph 10, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the calcination temperature is 955 to 985℃.

12. In Paragraph 10, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the above-mentioned calcination atmosphere is an oxygen atmosphere of 90 to 100 vol%.

13. In Paragraph 10, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the above calcination time is 5 to 12 hours.

14. A positive electrode for a lithium secondary battery comprising a positive electrode active material according to claim 1.

15. A lithium secondary battery comprising a positive electrode for a lithium secondary battery according to paragraph 14.

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