Positive electrode active material for secondary batteries

Abstract

This invention provides a positive electrode active material that significantly improves the stability, charge / discharge capacity, and efficiency characteristics of secondary batteries. [Solution] The positive electrode active material particles comprise a bulk material and a first coating material, the first coating material comprising zirconium (Zr), and in a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles, the first coating material may be in the shape of dots.

Description

Technical Field

[0001] The present invention relates to a positive electrode active material particle and a positive electrode active material for a secondary battery containing the same, and more particularly, to a composition, coating method, coating form, etc. of a coating material containing zirconium (Zr) in a lithium composite oxide, and a positive electrode active material that significantly improves the stability, charge-discharge capacity, and efficiency characteristics of a secondary battery when applied to the secondary battery.

Background Art

[0002] With the development of portable mobile electronic devices such as smartphones, MP3 players, and tablet PCs, the demand for secondary batteries capable of storing electrical energy has increased explosively.

[0003] In particular, with the emergence of electric vehicles, medium and large-sized energy storage systems, and portable devices that require high energy density, the demand for lithium secondary batteries is increasing.

[0004] As a lithium composite oxide contained in a positive electrode active material, the most spotlighted substance recently is lithium nickel (manganese / aluminum) cobalt oxide Li(Ni , Co y (Mn / Al)z)O2 (where x, y, and z are atomic fractions of independent oxide composition elements, 0 < x ≤ 1, 0 < y ≤ 1, 0 < z ≤ 1, and 0 < x + y + z ≤ 1).

[0005] This positive electrode active material has the advantage of exhibiting a high capacity because it is used at a higher voltage than LiCoO2, which has been actively studied and used as a positive electrode active material so far, and has the advantage of a low price because the Co content is relatively low.

[0006] However, such a lithium composite oxide is accompanied by volume changes due to the intercalation and deintercalation of lithium ions during charge and discharge. During charging and discharging, the primary particles of the lithium composite oxide undergo rapid volume changes, and repeated charging and discharging can cause cracks in the secondary particles, as well as collapse of the crystal structure or a phase transition of the crystal structure.

[0007] To compensate for these shortcomings, demand has begun to increase for high-nickel cathode active materials used in secondary batteries, which have a high nickel (Ni) content relative to the total metal content excluding lithium (Li). [Overview of the initiative] [Problems that the invention aims to solve]

[0008] The present invention aims to provide a positive electrode active material that significantly improves the stability, charge / discharge capacity, and efficiency characteristics of a secondary battery when applied to a secondary battery, by controlling the composition, coating method, and coating form of the zirconium (Zr)-containing coating material.

[0009] In particular, the present invention aims to provide a positive electrode active material with controlled composition, coating method, and coating form that can improve battery performance when applying a non-water-washing coating method, in order to compensate for the disadvantages of water-washing coating using a coating liquid. [Means for solving the problem]

[0010] A positive electrode active material particle according to one aspect of the present invention comprises a bulk material and a first coating material, the first coating material may include zirconium (Zr).

[0011] In a more preferred embodiment, the first coating material may be dot-shaped in a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles.

[0012] In a more preferred embodiment, the first coating material may include one or more selected from ZrO2 and lithium zirconium oxide.

[0013] In a more preferred embodiment, the molar percentage of zirconium (Zr) contained in the positive electrode active material particles relative to the positive electrode active material particles may be 0.01 mol% to 1.0 mol%.

[0014] In a more preferred embodiment, the positive electrode active material particles may contain 3 to 20 of the first coating material.

[0015] In a more preferred embodiment, the average particle size (D50) of the first coating material contained in the positive electrode active material particles may be 50 nm to 150 nm.

[0016] In a more preferred embodiment, the positive electrode active material particles further comprise a second coating material, the second coating material may contain cobalt (Co).

[0017] In a more preferred embodiment, the second coating material can coat a portion of the surface of the bulk material.

[0018] In a more preferred embodiment, in a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles, the coating area ratio of the second coating material relative to the total surface area may be 30% to 98%.

[0019] In a more preferred embodiment, the average particle size (D50) of the positive electrode active material particles may be 1.0 μm to 6.0 μm.

[0020] In a more preferred embodiment, the bulk material may consist of a single particle or may contain two to eight single particles in contact with each other.

[0021] The positive electrode active material according to a more preferred embodiment can include the positive electrode active material particles.

Advantages of the Invention

[0022] As one effect, the present invention provides a positive electrode active material with increased stability, enhanced bulk structure and coating structure, while suppressing direct contact between the surface and the electrolyte, in order to reduce the amount of gas generation that directly affects the reduction of lifespan.

[0023] As one effect, the present invention provides a positive electrode active material that significantly improves the stability, charge-discharge capacity and efficiency characteristics of a secondary battery.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a SEM image of the surface of positive electrode active material particles according to an embodiment of the present invention. [Figure 2] FIG. 2 is a SEM image of the surface of positive electrode active material particles according to an embodiment of the present invention. [Figure 3] FIG. 3 is a SEM image of the surface of positive electrode active material particles according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0025] Expressions such as "comprising" used in this specification should be understood as open-ended terms that encompass the possibility of including other configurations.

[0026] "Preferred" and "preferably" used in this specification refer to embodiments of the present invention that can provide predetermined advantages under a given environment.

[0027] However, it is not intended to exclude other embodiments from the scope of the present invention.

[0028] Also, the singular forms used in the specification and the appended claims can be construed to include the plural forms as well, unless otherwise indicated specifically in the context.

[0029] In other words, the technical characteristics of any one particle may also refer to the technical characteristics of multiple particles, or they may be intended to represent the average technical characteristics of multiple particles.

[0030] The numerical ranges used herein include lower and upper limits and all values ​​within those limits, increments logically derived from the form and width of the defined range, all values ​​that are doubly limited, and all possible combinations of upper and lower limits of numerical ranges that are limited in different forms.

[0031] Unless otherwise specified herein, values ​​outside the defined numerical range that may occur due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0032] The meanings of "≦", "greater than or equal to", or "less than or equal to" as described herein may be replaced with the meanings of "<", "greater than", or "less than".

[0033] On the other hand, the technical features described below relate to one embodiment that achieves the effects intended for the present invention as described above.

[0034] In other words, a positive electrode active material according to one aspect of the present invention, by including the technical features of one aspect described below, has its particle bulk structure and coating structure further enhanced, and can significantly improve the stability, charge / discharge capacity, and efficiency characteristics of a secondary battery.

[0035] This invention relates to positive electrode active material particles for secondary batteries and positive electrode active material containing a plurality of such particles.

[0036] The secondary battery of this invention is not limited in type, as long as it is a battery that converts external electrical energy into chemical energy for storage and reuse.

[0037] As an example, the present invention may relate to a positive electrode active material for lithium-ion secondary batteries.

[0038] The positive electrode active material particles according to one aspect of the present invention may include a bulk material and a first coating material.

[0039] First, let me explain the bulk material.

[0040] In one embodiment, the bulk material may be a lithium composite oxide.

[0041] In one embodiment, the bulk material may be a lithium composite oxide containing nickel (Ni).

[0042] In one embodiment, the bulk region may be a lithium composite oxide containing nickel (Ni) and cobalt (Co).

[0043] In one embodiment, the lithium composite oxide can be represented by the following chemical formula 1.

[0044] [Chemical formula 1] Li a Ni x M1 y M2 1-x-y O2

[0045] In the above chemical formula 1, M1 is selected from the group consisting of cobalt (Co), manganese (Mn), aluminum (Al), and combinations thereof, and M2 is selected from the group consisting of Zr, Mn, Al, B, S, Ba, Ce, Cr, F, Mg, V, Ti, Fe, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Na, K, Hf, Ta, Cu, and combinations thereof, with 0.9 ≤ a ≤ 1.2 and 0.1 ≤ x < 1.0, 0.0 ≤ y ≤ 0.5, and 0.0 ≤ 1 - xy ≤ 0.5.

[0046] In one embodiment, in the above chemical formula 1, a, which represents the relative lithium (Li) mol% to the total transition metal mol% excluding lithium (Li), may be 0.9 or more, 1.0 or more, 1.2 or less, 1.1 or less, or 1.05 or less.

[0047] In one embodiment, in the above chemical formula 1, x, which represents the relative nickel (Ni) mole% to the total transition metal mole% excluding lithium (Li), can be 0.1 or higher, 0.2 or higher, 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, or 0.9 or higher. In particular, the present invention may be a high-nickel (high-Ni) oxide in which x is 0.5 or higher.

[0048] While high-nickel cathode active materials have the advantage of high energy density, the high Li / M ratio during manufacturing results in a high residual lithium content after firing, making cell manufacturing difficult due to gelation during electrode slurry production. To address this, a water washing process is introduced to remove residual lithium, but this process damages the cathode surface, leading to a decrease in battery performance.

[0049] Furthermore, due to the high Ni content, the structure becomes unstable, leading to increased reactions with the electrolyte at the particle surface and interface. This results in the release of large amounts of gas during repeated charge-discharge processes, which reduces the lifespan characteristics. However, the present invention can resolve these problems, which are more serious with high-nickel (high-Ni) cathode active materials.

[0050] In one embodiment, in the above chemical formula 1, if y represents the total transition metal mole percent excluding lithium (Li) relative to the cobalt (Co) mole percent, then y may be 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0051] In one embodiment, in the above chemical formula 1, if y represents the molar percentage of Al and / or Mn relative to the molar percentage of all transition metals excluding lithium (Li), then y may be 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less, 0.1 or more, 0.2 or more, or 0.3 or more.

[0052] In a more preferred embodiment, the bulk region may be doped with one or more elements selected from cobalt (Co), zirconium (Zr), barium (Ba), strontium (Sr), titanium (Ti), aluminum (Al), niobium (Nb), vanadium (V), molybdenum (Mo), boron (B), yttrium (Y), tungsten (W), magnesium (Mg), zinc (Zn), iron (Fe), tantalum (Ta), silicon (Si), and fluorine (F).

[0053] More preferably, the bulk region may be doped with one or more elements selected from cobalt (Co), zirconium (Zr), barium (Ba), strontium (Sr), aluminum (Al), and titanium (Ti).

[0054] During the production of the positive electrode active material according to the present invention, a lithium composite oxide can be produced by heat-treating the hydroxide precursor and the lithium compound.

[0055] At this time, by heat-treating the doping element together, the primary particles can be uniformly doped within their lattice structure.

[0056] Another aspect of this approach is that when lithium composite oxide particles are coated, some of the coating elements can be present within the lattice structure of the primary particles contained within the lithium composite oxide particles.

[0057] In this case, the coating element can be doped into the lithium composite oxide particles.

[0058] On the other hand, lithium composite oxide particles relating to the bulk material are defined to include all of the elements doped in this manner.

[0059] In one embodiment, zirconium (Zr) is a coating element that is applied after the production of lithium composite oxide, but can be doped during the coating heat treatment and can be present within the lattice structure of the primary particles.

[0060] In one embodiment, cobalt (Co) is a coating element that is applied after the production of lithium composite oxide, but can be doped during the coating heat treatment and can be present within the lattice structure of the primary particles.

[0061] In one embodiment, aluminum (Al) is a coating element that is applied after the production of lithium composite oxide, but can be doped during the coating heat treatment and can be present within the lattice structure of the primary particles.

[0062] As described above, the present invention can further strengthen the bulk structure by controlling the dopant and bulk composition, thereby improving the stability, charge / discharge capacity, and efficiency characteristics of secondary batteries.

[0063] Next, the first coating material will be described.

[0064] In one embodiment, the first coating material may be a region distinct from the lithium composite oxide particles, which are a bulk material.

[0065] In one embodiment, the first coating material may contain zirconium (Zr), and in a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles, the first coating material may be in the shape of dots (see Figure 1).

[0066] This invention confirms that by coating with zirconium (Zr) in a dot shape, the coating structure can be further strengthened, and the stability, charge / discharge capacity, and efficiency characteristics of secondary batteries can be further improved.

[0067] On the other hand, in the present invention, the scanning electron microscope (SEM) image was obtained using a JSM-IT8800 (JEOL) at a voltage of 2kV to obtain a particle surface FE-SEM image.

[0068] In a more preferred embodiment, the first coating material may have the highest brightness in a low-angle backscatter electron (LABE) mode scanning electron microscope (SEM) image of one surface of the positive electrode active material particles (see Figure 1).

[0069] This difference in brightness could be due to differences in the type and density of the coating elements.

[0070] In this invention, the scanning electron microscope (SEM) image was obtained by measuring the particle surface using a voltage of 2kV in low-angle backscatter electron (LABE) mode.

[0071] In a more preferred embodiment, the first coating material may include ZrO2 and / or lithium zirconium oxide.

[0072] In a more preferred embodiment, the molar percentage of zirconium (Zr) contained in the positive electrode active material particles relative to the positive electrode active material particles may be 0.01 mol% or more, 0.05 mol% or more, 0.1 mol% or more, 1.0 mol% or less, 0.5 mol% or less, 0.4 mol% or less, 0.3 mol% or less, 0.2 mol% or less, or 0.15 mol% or less, and more preferably 0.05 mol% to 0.2 mol%.

[0073] The present invention has confirmed that, considering the coating shape of zirconium (Zr), including it in the aforementioned molar content can further improve the charge / discharge capacity and efficiency characteristics of secondary batteries.

[0074] In a more preferred embodiment, the positive electrode active material particles may contain 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, or 10 or less of the first coating material.

[0075] The present invention can further strengthen the coating structure and improve the charge / discharge capacity and efficiency characteristics of a secondary battery by including the number of first coating materials within the aforementioned numerical range.

[0076] In a more preferred embodiment, the average particle size (D50) of the first coating material contained in the positive electrode active material particles may be 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, 150 nm or less, 140 nm or less, or 130 nm or less, and more preferably 70 nm to 130 nm.

[0077] The present invention can further strengthen the coating structure and improve the charge / discharge capacity and efficiency characteristics of secondary batteries by adjusting the average particle size (D50) of the first coating material to the aforementioned numerical range.

[0078] On the other hand, in this invention, the average particle size (D50) of the first coating material was calculated by converting units using a Scale bar at the same magnification of the SEM image x20.0K, measuring the diameters of 5 to 15 arbitrarily selected first coating materials using the Image J program, and then calculating the average.

[0079] On the other hand, in the present invention, the average particle size (D50) of the first coating material can be interpreted as being such that the average value of the diameters of 5 to 15 arbitrarily selected first coating materials satisfies the aforementioned numerical range.

[0080] As described above, by controlling the composition, form, etc. of the first coating material, the coating structure can be further strengthened, and the stability, charge-discharge capacity, and efficiency characteristics of the secondary battery can be further improved.

[0081] In one aspect, the positive electrode active material particles can further include a second coating material, and the second coating material can include cobalt (Co).

[0082] In one aspect, the cobalt (Co) can exist in the form of LiCoO2, Li 1+a CoO2(0 < a < 1) , Li 1-b CoO2(0 < b < 1) , Co q O r (0 < q < 10, 0 < r < 10), and / or in the form of Co(OH)2, etc.

[0083] In one aspect, using an electron beam irradiated at an acceleration voltage of 1 kV on the second coating material on the surface of the positive electrode active material particles, the average concentration of elements from the surface of the positive electrode active material particles to the depth penetrated by the electron beam is measured by EP-EDS (Energy Profiling-Energy Dispersive X-Ray Spectroscopy). The average concentration of the cobalt (Co) element can be 20 at% or more, 30 at% or more, 40 at% or more, 50 at% or more, or 80 at% or less, 70 at% or less, 60 at% or less, 50 at% or less, 40 at% or less, or 30 at% or less.

[0084] In one embodiment, the second coating material may further contain, in addition to cobalt (Co), one or more selected from aluminum (Al), titanium (Ti), zirconium (Zr), magnesium (Mg), zinc (Zn), molybdenum (Mo), iron (Fe), nickel (Ni), barium (Ba), tungsten (W), strontium (Sr), yttrium (Y), niobium (Nb), vanadium (V), boron (B), tantalum (Ta), silicon (Si), and fluorine (F).

[0085] More preferably, the second coating material may further contain one or more selected from aluminum (Al), zirconium (Zr), boron (B), tungsten (W), yttrium (Y), and titanium (Ti), in addition to cobalt (Co).

[0086] More preferably, the second coating material may further contain aluminum (Al) in addition to cobalt (Co).

[0087] More preferably, considering the coating method, coating composition, and coating form of the present invention, when cobalt (Co), zirconium (Zr), and aluminum (Al) are coated on the bulk material, the charge / discharge capacity and efficiency characteristics can be further improved.

[0088] As described above, the present invention can further strengthen the coating structure by controlling the composition of the second coating material, thereby improving the stability, charge / discharge capacity, and efficiency characteristics of the secondary battery.

[0089] In a more preferred embodiment, the second coating material can coat a portion of the surface of the bulk material.

[0090] In a more preferred embodiment, in a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles, the coating area ratio of the second coating material relative to the total area of ​​the surface may be 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 98% or less, or 95% or less, and more preferably 80% to 96%.

[0091] The present invention can further strengthen the coating structure and improve the stability, charge / discharge capacity, and efficiency characteristics of secondary batteries by adjusting the coating area ratio of the second coating material to the aforementioned numerical range.

[0092] In this invention, the coating area ratio was measured using the ImageJ program on a scanning electron microscope (SEM) image of one surface of a positive electrode active material particle.

[0093] On the other hand, in the present invention, the coating area ratio can be interpreted as fitting the description if the coating area ratio measured on one surface of arbitrarily selected positive electrode active material particles satisfies the aforementioned numerical range.

[0094] On the other hand, unlike the wet process in which active material particles are immersed in a coating liquid during the first and / or second coating, the present invention allows for the realization of the coating area and form by adjusting the coating content, heat treatment temperature and time, particle size, etc., through a dry coating process during secondary heat treatment without a water washing step.

[0095] In particular, the present invention controls the composition of the coating material, the coating method, and the coating form to further improve battery performance when applying a non-water-washing coating method, in order to compensate for the disadvantages of water-washing coating using a coating liquid.

[0096] In a more preferred embodiment, the thickness of the second coating material, measured perpendicularly from the surface of the bulk material, may be 1 nm to 100 nm, more preferably 20 nm to 60 nm.

[0097] In this invention, the thickness of the second coating material was determined by obtaining a cross-sectional SEM image of the lithium composite oxide at a voltage of 2kV using JSM-7610FPlus (JEOL), then measuring the thickness of the second coating material at 10 arbitrarily selected locations and calculating the average value.

[0098] On the other hand, if the thickness of the second coating material at 10 arbitrarily selected locations in the present invention satisfies the aforementioned numerical range, it can be interpreted as falling under this category.

[0099] As described above, the present invention can further strengthen the coating structure by controlling the coating method and coating form for the second coating material, thereby improving the stability, charge / discharge capacity, and efficiency characteristics of the secondary battery.

[0100] On the other hand, in one embodiment, the first coating material may be present on the surface of the bulk material or on the surface of the second coating material.

[0101] The average particle size (D50) of the positive electrode active material particles according to one aspect of the present invention may be 1.0 μm or more, 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, 6.0 μm or less, 5.5 μm or less, 5 μm or less, or 4.5 μm or less, and more preferably 3.0 μm to 4.0 μm.

[0102] In this invention, the average diameter (D50) is the particle size at the 50% point of the area cumulative distribution by particle size, and this can be measured using the laser diffraction method.

[0103] Specifically, the powder to be measured is dispersed in a dispersion medium, then introduced into a commercially available laser diffraction particle size analyzer. The particle size distribution can then be calculated by measuring the difference in diffraction patterns due to particle size as the particles pass through the laser beam.

[0104] On the other hand, the bulk material may be a particle formed by the contact of at least one or more single particles. Here, a single particle means a primary particle.

[0105] In a more preferred embodiment, the bulk material may consist of a single particle, or may contain eight or fewer, seven or fewer, six or fewer, five or fewer, four or fewer, three or fewer, or two or fewer single particles in contact with each other.

[0106] In one aspect, when the bulk material consists of a single particle, the average particle size (D50) may be 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, 6.0 μm or less, 5.5 μm or less, 5 μm or less, or 4.5 μm or less, and more preferably, it may consist of a single particle of 3.0 μm to 4.0 μm.

[0107] On one side, if the bulk material contains two to eight single particles in contact with each other, then two to eight single particles measuring 1 μm or more, 3 μm or less, or 2 μm or less may be contained in contact with each other.

[0108] In one embodiment, the aspect ratio (longest major axis / shortest minor axis) of the single particle may be 1 or more, 2 or more, 3 or less, 2 or less, 1.5 or less, 1.2 or less, or 1.1 or less.

[0109] A positive electrode active material according to one aspect of the present invention may contain a plurality of positive electrode active material particles. A positive electrode according to one aspect of the present invention includes the positive electrode active material.

[0110] Aside from using the aforementioned positive electrode active material, the positive electrode has a known structure and can be manufactured by a known manufacturing method.

[0111] The binder, conductive material, and solvent are not particularly limited, as long as they can be used on the positive electrode current collector of a secondary battery.

[0112] A secondary battery according to one aspect of the present invention includes the positive electrode active material.

[0113] The secondary battery may specifically include a positive electrode, a negative electrode located opposite the positive electrode, and an electrolyte between the positive electrode and the negative electrode, but is not particularly limited as long as it can be used as a secondary battery.

[0114] The following describes embodiments of the present invention in more detail. Manufacturing of positive electrode active material

[0115] <Example 1> A lithium composite oxide NiCoMn(OH)2 hydroxide precursor (Ni:Co:Mn = 95:2:3 (at%)) was synthesized through a known co-precipitation method using nickel sulfate, cobalt sulfate, and manganese sulfate. Next, the hydroxide precursor and LiOH (Li / (Ni+Co+Mn) mol ratio = 1.05) were mixed, and then the mixture was heat-treated (primary calcination) in an O2 atmosphere at 790°C for 12 hours to obtain a lithium composite oxide. Subsequently, the material was crushed using a jet-mill to produce lithium composite oxide in single-particle form. Next, lithium composite oxide particles were mixed with 23 mol% Co(OH), 20.1 mol% ZrO, and 30.1 mol% Al2O at 700°C in an O2 atmosphere and heat-treated (secondary calcination) in an oxygen atmosphere for 12 hours to produce a positive electrode active material with a particle size of 3 μm to 4 μm.

[0116] <Example 2> The positive electrode active material was manufactured in the same manner as in Example 1, except that instead of mixing 23 mol% Co(OH), 20.1 mol% ZrO, and 30.1 mol% Al2O, 23 mol% Co(OH) and 20.1 mol% ZrO.

[0117] <Example 3> The positive electrode active material was manufactured in the same manner as in Example 1, except that instead of mixing 23 mol% Co(OH), 20.1 mol% ZrO, and 30.1 mol% Al2O, 23 mol% Co(OH) and 20.5 mol% ZrO.

[0118] <Comparative Example 1> The positive electrode active material was manufactured in the same manner as in Example 1, except that instead of mixing 23 mol% Co(OH), 20.1 mol% ZrO, and 30.1 mol% Al2O, 23 mol% Co(OH) and 20.1 mol% TiO.

[0119] <Comparative Example 2> The positive electrode active material was manufactured in the same manner as in Example 1, except that instead of mixing 23 mol% Co(OH), 20.1 mol% ZrO, and 30.1 mol% Al2O, 23 mol% Co(OH) and 20.5 mol% TiO.

[0120] <Comparative Example 3> The positive electrode active material was manufactured in the same manner as in Example 1, except that instead of mixing 23 mol% Co(OH), 20.1 mol% ZrO, and 30.1 mol% Al2O, 23 mol% Co(OH) and 30.1 mol% Al2O.

[0121] <Comparative Example 4> The positive electrode active material was manufactured in the same manner as in Example 1, except that instead of mixing 23 mol% Co(OH), 20.1 mol% ZrO, and 30.1 mol% Al2O, 23 mol% Co(OH) and 30.5 mol% Al2O.

[0122] <Comparative Example 5> The positive electrode active material was manufactured in the same manner as in Example 1, except that instead of mixing 23 mol% Co(OH), 20.1 mol% ZrO, and 30.1 mol% Al2O, a mixture of 23 mol% Co(OH), 20.1 mol% TiO, and 30.1 mol% Al2O was used.

[0123] Manufacturing of lithium-ion batteries A cathode slurry was prepared by dispersing 96 wt% of each of the cathode active materials produced by the above manufacturing example, 2 wt% of artificial graphite, and 2 wt% of PVDF binder in 8 g of N-methyl-2-pyrrolidone (NMP).

[0124] The aforementioned positive electrode slurry was uniformly applied to a 15 μm thick aluminum thin film and vacuum-dried at 135°C to produce a positive electrode for a lithium secondary battery.

[0125] A coin cell was manufactured using a lithium foil as the counter electrode for the positive electrode, a porous polyethylene membrane (Celgard 2300, thickness: 25 μm) as the separation membrane, and an electrolyte containing ethylene carbonate and ethyl methyl carbonate mixed in a volume ratio of 3:7 with LiPF6 present at a concentration of 1.15 M.

[0126] <Experimental Example 1> SEM Analysis For the positive electrode active material particles according to Example 1, a FE-SEM (JSM-IT8800, JEOL) was used to obtain particle surface images at a voltage of 2kV, which are shown in Figures 1 to 3.

[0127] <Experimental Example 2> Measurement of average particle size (D50) of Zr white spots For the surface of the positive electrode active material particles according to Example 1, the diameters of 7 to 12 first coating materials were measured using the ImageJ program after unit conversion through a Scale bar at the same magnification x20.0K SEM image, and the average value was calculated, as shown in Tables 1 to 3 below. [Table 1] [Table 2] [Table 3]

[0128] <Experimental Example 3> Charge / Discharge Capacity and Efficiency For the lithium secondary batteries of the above-mentioned examples and comparative examples, the initial charge capacity and initial discharge capacity were measured through charge / discharge experiments using an electrochemical analyzer (Toyo, Toscat-3100) at 25°C, with a voltage range of 3.0V to 4.3V and a discharge rate of 0.1C. The efficiency was calculated and is shown in Table 4 below. [Table 4]

Claims

1. A bulk material; and a first coating material; The first coating material contains zirconium (Zr), In a scanning electron microscope (SEM) image of one surface of a positive electrode active material particle, the first coating material is dot-shaped. Positive electrode active material particles.

2. In claim 1, The first coating material is ZrO 2 and one or more selected from lithium zirconium oxide, Positive electrode active material particles.

3. In claim 1, Compared to the positive electrode active material particles, the molar percentage of zirconium (Zr) contained in the positive electrode active material particles is 0.01 mol% to 1.0 mol%. Positive electrode active material particles.

4. In claim 1, The positive electrode active material particles include 2 to 20 of the first coating material. Positive electrode active material particles.

5. In claim 1, The average particle size (D50) of the first coating material contained in the positive electrode active material particles is 50 nm to 150 nm. Positive electrode active material particles.

6. In claim 1, The positive electrode active material particles further comprise a second coating material, the second coating material comprising cobalt (Co). Positive electrode active material particles.

7. In claim 6, The second coating material coats a portion of the surface of the bulk material. Positive electrode active material particles.

8. In claim 6, In a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles, the coating area ratio of the second coating material relative to the total surface area is 30% to 98%. Positive electrode active material particles.

9. In claim 1, The average particle size (D50) of the positive electrode active material particles is 1.0 μm to 6.0 μm. Positive electrode active material particles.

10. In claim 1, The bulk material consists of one single particle, or contains two to eight single particles in contact with each other. Positive electrode active material particles.

11. The positive electrode active material particles according to claim 1, Cathode active material.

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