Positive electrode active material for secondary battery

Abstract

According to one aspect of the present invention, the positive electrode active material particle comprises a body region and a coating region, the coating region comprising cobalt (Co), and the coating area ratio of the coating region relative to the total area of ​​the surface can be 83% to 96% in a scanning electron microscope (SEM) image of a surface of the positive electrode active material particle.

Description

Technical Field

[0001] The present invention relates to positive electrode active material particles and a positive electrode active material for secondary batteries comprising the same, and more specifically, to a positive electrode active material which, when applied to a secondary battery, significantly improves the stability, lifespan and output performance of the secondary battery by controlling the composition, coating method, coating morphology and the like of the cobalt (Co)-containing coating material of the lithium composite oxide. Background Art

[0002] With the development of portable mobile electronic devices such as smartphones, MP3 players and tablet computers, the demand for secondary batteries capable of storing electrical energy has increased explosively. In particular, with the emergence of electric vehicles, large and medium-sized energy storage systems, and portable devices requiring high energy density, the demand for lithium secondary batteries is increasing.

[0003] As a lithium composite oxide contained in a positive electrode active material, the most prominently noticed material in recent years is lithium nickel (manganese / aluminum) cobalt oxide Li(Ni x Co y (Mn / Al) z )O2 (wherein x, y and z above are each independently the atomic fraction of the constituent element of the oxide, 0<x≤1, 0<y≤1, 0<z≤1, and 0<x+y+z≤1). Compared with LiCoO2, which has been actively studied and used as a positive electrode active material in the past, this positive electrode active material has the advantage of high capacity due to being used at a higher voltage, and has the advantage of low cost due to a relatively low Co content.

[0004] However, such lithium composite oxides undergo volume changes accompanying the intercalation and deintercalation of lithium ions during charging and discharging. There are the following problems: during charging and discharging, the volume of primary particles of the lithium composite oxide changes sharply, or cracks occur in secondary particles along with repeated charging and discharging, or collapse or phase transition of the crystal structure occurs.

[0005] To compensate for these disadvantages, as a positive electrode active material for secondary batteries, the demand for high-nickel positive electrode active materials in which the content of nickel (Ni) relative to the total metal content excluding lithium (Li) is high has started to increase. Summary of the Invention

[0006] Technical Problem

[0007] The present invention aims to provide a positive electrode active material which, when applied to a secondary battery, significantly improves the stability, lifespan and output performance of the secondary battery by controlling the composition, coating method, coating morphology and the like of the cobalt (Co)-containing coating material.

[0008] In particular, the present invention aims to provide a positive electrode active material with a controlled coating area ratio that can improve battery performance when using a non-water-washed cobalt (Co) coating method to overcome the disadvantages of water-washed coating using a coating solution.

[0009] Technical solution

[0010] According to one aspect of the present invention, the positive electrode active material particle comprises a body region and a coating region, the coating region comprising cobalt (Co), and the coating area ratio of the coating region relative to the total area of ​​the surface can be 83% to 96% in a scanning electron microscope (SEM) image of a surface of the positive electrode active material particle.

[0011] As a more preferred aspect, the positive electrode active material particles include more than one unit coating area. When the unit coating area refers to a closed coating area on the surface of the bulk region that is not connected to other coating areas, the average area of ​​the unit coating area can be from 3.0 μm² to 8.0 μm².

[0012] As a more preferred aspect, the number of unit coating areas in the positive electrode active material particles can be from 1 to 10.

[0013] As a more preferred aspect, on the surface of the body region, the average inclination of the slope of the periphery of the closed coating area can be less than 70°.

[0014] As a more preferred aspect, the average thickness of the coating area measured vertically from the surface of the body region can be from 20 nm to 60 nm.

[0015] As a more preferred aspect, the coating area may further comprise one or more of aluminum (Al), zirconium (Zr), boron (B), tungsten (W), yttrium (Y), and titanium (Ti).

[0016] As a more preferred aspect, the body region may be doped with one or more elements selected from cobalt (Co), zirconium (Zr), barium (Ba), strontium (Sr), aluminum (Al) and titanium (Ti).

[0017] As a more preferred aspect, the average particle size (D50) of the positive electrode active material particles can be from 2.0 μm to 6.0 μm.

[0018] As a more preferred aspect, the body region may consist of a single particle or contain two to eight contacting single particles.

[0019] According to one aspect of the present invention, the positive electrode active material may comprise said positive electrode active material particles.

[0020] The effects of the invention

[0021] As an effect, the present invention provides a positive electrode active material that reduces the amount of gas generated, thereby suppressing direct contact between the surface and the electrolyte, while further improving stability and strengthening the bulk structure and coating structure.

[0022] As an effect, the present invention provides a positive electrode active material that significantly improves the stability, lifespan and output performance of secondary batteries. Attached Figure Description

[0023] Figure 1 This is a SEM image of the surface of a positive electrode active material particle manufactured according to the present invention.

[0024] Figure 2 This is a SEM image of the surface of a positive electrode active material particle manufactured according to the present invention. Detailed Implementation

[0025] The terms “comprising” and similar expressions used in this specification should be understood as open-ended terms that imply the possibility of including other components.

[0026] As used in this specification, "preferred" and "ideally" refer to embodiments of the invention that provide specific advantages under particular conditions. However, this is not intended to exclude other embodiments from the scope of the invention.

[0027] Furthermore, the singular form used in the specification and appended claims may also include the plural form unless the context specifically indicates otherwise. That is, a technical feature relating to a single particle may refer to technical features relating to multiple particles, and may also refer to the average technical features of multiple particles.

[0028] The numerical ranges used in this specification include lower and upper limits, as well as all values ​​within that range, increments logically derived from the form and width of the defined range, all double-qualified values, and all possible combinations of upper and lower limits of numerical ranges qualified in different forms.

[0029] Unless otherwise defined, values ​​that may be outside the numerical range due to experimental errors or rounding are also included in the defined numerical range.

[0030] The meanings of “≤”, “above” or “below” as used in this specification may be replaced by the meanings of “<”, “exceed” or “not yet”.

[0031] On the other hand, the following technical features are one aspect of achieving the effects to be achieved by the present invention.

[0032] That is, the positive electrode active material according to one aspect of the present invention, by including the technical features of the following aspect, can further strengthen the bulk structure and coating structure of the particles and significantly improve the stability, lifespan and output performance of the secondary battery.

[0033] This invention relates to positive electrode active material particles for secondary batteries and positive electrode active materials comprising a plurality of such particles.

[0034] The secondary battery of the present invention is not limited in type as long as it is capable of converting external electrical energy into chemical energy for storage and reuse. For example, the present invention may relate to positive electrode active materials for lithium-ion secondary batteries.

[0035] According to one aspect of the present invention, the positive electrode active material particles include a body region and a coating region.

[0036] First, the body region will be described.

[0037] As one aspect, the body region may be a lithium composite oxide.

[0038] In one respect, the body region may be a lithium composite oxide containing nickel (Ni).

[0039] In one aspect, the body region may be a lithium composite oxide comprising nickel (Ni) and cobalt (Co).

[0040] In one respect, the lithium composite oxide can be represented by the following chemical formula 1.

[0041] [Chemical Formula 1]

[0042] Li a Ni x M1 y M2 (1-x-y) O2

[0043] 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, Ta and combinations thereof, and 0.9≤a≤1.2 and 0.1≤x<1.0, 0.0≤y≤0.5, and 0.0≤1-xyz≤0.5.

[0044] As one aspect, in the above chemical formula 1, the 'a' representing the mol% of lithium (Li) relative to the total mol% of transition metals other than lithium (Li) can be 0.9 or more, 1.0 or more, 1.2 or less, 1.1 or less, or 1.05 or less.

[0045] In one aspect, in the above chemical formula 1, x, which represents the molar percentage of nickel (Ni) relative to the total molar percentage of transition metals other than lithium (Li), can be 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more. In particular, the present invention can be a high-Ni oxide with x of 0.5 or more.

[0046] This high-nickel cathode active material has the advantage of high energy density. On the other hand, due to the high Li / M ratio during the manufacturing process, a high residual lithium content remains in the cathode active material after sintering. This causes difficulties in cell manufacturing due to gelation during electrode slurry production. Therefore, although a water washing process is introduced to remove residual lithium, there is a problem that the cathode surface is damaged during the water washing process, leading to a decrease in battery performance.

[0047] In addition, the following problems exist: due to the high Ni content, the structure is unstable, the reaction with the electrolyte at the particle surface and interface increases, and a large amount of gas is released during repeated charge and discharge, thus reducing the lifetime characteristics; while the present invention is particularly able to solve these more serious problems in high-Ni cathode active materials.

[0048] As one aspect, in the above chemical formula 1, when y represents the molar percentage of cobalt (Co) relative to the total molar percentage of transition metals other than lithium (Li), y can be less than 0.5, less than 0.4, less than 0.3, less than 0.2, or less than 0.1.

[0049] As one aspect, in the above chemical formula 1, when y represents the mol% of Al and / or Mn relative to the total mol% of transition metals other than lithium (Li), y can be less than 0.5, less than 0.4, less than 0.3, less than 0.2, less than 0.1, more than 0.1, more than 0.2, or more than 0.3.

[0050] As a more preferred aspect, the body 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).

[0051] More preferably, the body region may be doped with one or more elements selected from cobalt (Co), zirconium (Zr), barium (Ba), strontium (Sr), aluminum (Al) and titanium (Ti).

[0052] In manufacturing the positive electrode active material of the present invention, a hydroxide precursor and a lithium compound can be heat-treated to produce a lithium composite oxide. In this case, by heat-treating the dopant elements together, they can be uniformly doped into the lattice structure of the primary particles.

[0053] As another approach, during the coating process of lithium composite oxide particles, some of the coating elements can be present within the crystal lattice structure of the primary particles contained within the lithium composite oxide particles. In this case, the coating elements can be doped into the lithium composite oxide particles.

[0054] On the other hand, the lithium composite oxide particles in the body region are defined as encompassing all such doped regions.

[0055] As one aspect, cobalt (Co) is a coating element used after the manufacture of lithium composite oxides, and can also be doped during coating heat treatment and exist within the lattice structure of primary particles.

[0056] As one aspect, aluminum (Al) is a coating element used after the manufacture of lithium composite oxides, and can also be doped during coating heat treatment and exist within the lattice structure of primary particles.

[0057] As one aspect, zirconium (Zr) is a coating element used after the manufacture of lithium composite oxides, and can also be doped during coating heat treatment and exist within the lattice structure of primary particles.

[0058] As described above, by controlling the doping elements and the composition of the bulk region, the coating structure can be further enhanced, and the stability, lifespan, and output performance of the secondary battery can be further improved.

[0059] Next, the coated area will be described.

[0060] In one respect, the coating area may be a region distinct from the lithium composite oxide particles that constitute the body region.

[0061] When coating lithium composite oxide particles according to one aspect of the present invention, some coating elements may form coating areas containing coating material. This coating material may be present on the surface of secondary particles of the lithium composite oxide particles and / or at the grain boundaries between primary particles. Here, the grain boundary between primary particles refers to a region encompassing the space between the primary particles and the surface of the primary particles.

[0062] As a more preferred aspect, the coating area may contain cobalt (Co).

[0063] As one aspect, the cobalt (Co) can be in the coating area as LiCoO2, Li (1+a)CoO₂ (0.1<a<1), Li (1-b) CoO₂ (0.1<b<1), Co q O r (0<q<10, 0<r<10) and / or exists in forms such as Co(OH)₂.

[0064] In one aspect, for the coating region on the surface of the positive electrode active material particle, the average concentration of cobalt (Co) element measured by EP-EDS (Energy Profiling-Energy Dispersive X-Ray Spectroscopy, which measures the average concentration of elements from the surface of the positive electrode active material particle to the penetration depth of an electron beam irradiated at an acceleration voltage of 1 kV) can be 20 at% or more, 30 at% or more, 40 at% or more, 50 at% or more, 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.

[0065] In a more preferred aspect, in addition to cobalt (Co), the coating region may further contain one or more elements selected from the group consisting of 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).

[0066] More preferably, in addition to cobalt (Co), the coating region may further contain one or more elements selected from the group consisting of aluminum (Al), zirconium (Zr), boron (B), tungsten (W), yttrium (Y) and titanium (Ti).

[0067] More preferably, in addition to cobalt (Co), the coating region may further contain one or more elements selected from the group consisting of aluminum (Al), zirconium (Zr) and boron (B).

[0068] More preferably, in addition to cobalt (Co), the coating region may further contain two or more elements selected from the group consisting of aluminum (Al), zirconium (Zr) and boron (B).

[0069] More preferably, in addition to cobalt (Co), the coating region further contains aluminum (Al), zirconium (Zr) and boron (B).

[0070] On the other hand, as an example, the molar content of each coating element and / or doping element contained in the positive electrode active material can be 5.0 mol% or less, 3.0 mol% or less, or 1.0 mol% or less.

[0071] For example, when the positive electrode active material contains aluminum (Al), the content of aluminum (Al) can be from 1.0 mol% to 2.0 mol% relative to the total content of the positive electrode active material.

[0072] For example, when the positive electrode active material contains zirconium (Zr), the content of zirconium (Zr) can be from 0.1 mol% to 1.0 mol% relative to the total content of the positive electrode active material.

[0073] For example, when the positive electrode active material contains barium (Ba), the content of barium (Ba) can be from 0.05 mol% to 0.15 mol% relative to the total content of the positive electrode active material.

[0074] As described above, by controlling the coating composition, the coating structure can be further enhanced, and the stability, lifespan, and output performance of the secondary battery can be further improved.

[0075] As a more preferred aspect, in a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles, the coating area ratio of the coated region relative to the total area of ​​the surface can be 96% or less, 95% or less, 93% or less, 90% or less, 83% or more, 85% or more, 87% or more, or 90% or more. By adjusting the coating area ratio to the above-mentioned numerical range, the present invention can further enhance the coating structure and further improve the stability, lifespan, and output performance of the secondary battery.

[0076] In this invention, the coating area ratio is obtained by measuring the area using ImageJ program in a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles.

[0077] On the other hand, in this invention, the coating area ratio measured on one surface of any selected positive electrode active material particle can be interpreted as belonging to this range as long as it meets the above-mentioned numerical range.

[0078] On the other hand, unlike the wet process of immersing active material particles in a coating liquid, the present invention can achieve the above-mentioned coating area and morphology by adjusting the coating content, heat treatment temperature and time, particle size, etc., through a dry coating process during the second heat treatment without a water washing step.

[0079] In particular, when the present invention applies a non-water-wash coating method to overcome the disadvantages of water-wash coating using coating liquid, it controls the composition of the coating material, the coating method, and the coating morphology in order to further improve battery performance.

[0080] In one respect, the positive electrode active material particles may contain more than one "unit coating area".

[0081] The unit coating area refers to a closed coating area on the surface of the bulk region that is not connected to other coating areas.

[0082] More preferably, the average value of the unit coating area can be 3.0 μm² or more, 3.2 μm² or more, 3.5 μm² or more, 8.0 μm² or less, 7.0 μm² or less, 6.0 μm² or less, 5.0 μm² or less, 4.5 μm² or less, 4.0 μm² or less, or 3.8 μm² or less, and more preferably, it can be 3.0 μm² to 5.0 μm² or less. By adjusting the unit coating area to the above-mentioned numerical range, the present invention can further enhance the coating structure and further improve the stability, lifespan, and output performance of the secondary battery.

[0083] In this invention, the average area of ​​the unit coated area is obtained by averaging the areas of arbitrarily selected 2 to 5 unit coated areas in a scanning electron microscope (SEM) image. Furthermore, in this invention, any arbitrarily selected 2 to 5 unit coated areas whose average area satisfies the aforementioned numerical range can be interpreted as belonging to this range.

[0084] As a more preferred aspect, the number of unit coating areas in the positive electrode active material particles can be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, less than 10, less than 9, less than 8, less than 7, less than 6, less than 5, less than 4, less than 3, or less than 2. By adjusting the number of unit coating areas to the above-mentioned numerical range, the present invention can further enhance the coating structure and further improve the stability, lifespan, and output performance of the secondary battery.

[0085] As a more preferred aspect, the average thickness of the coating area measured in a vertical direction from the surface of the body region can be 20 nm or more, 30 nm or more, 60 nm or less, or 50 nm or less.

[0086] In this invention, the average thickness of the coating area is obtained by using a JSM-7610FPlus (JEOL) to obtain a cross-sectional SEM image of the lithium composite oxide at a voltage of 2kV, then measuring the thickness of the coating area at arbitrarily selected 10 locations and calculating the average value. On the other hand, in this invention, as long as the average thickness of the coating area at arbitrarily selected 10 locations meets the above-mentioned numerical range, it can be interpreted as belonging to this range.

[0087] On the other hand, the closed coating area can be a different shape than island-like protrusions, islands, and / or uneven shapes (see reference). Figure 2 ).

[0088] As a more preferred aspect, when observing the slope of the periphery of the closed coating area, the average inclination of the slope of the periphery of the closed coating area on the surface of the body region can be less than 70°, less than 60°, less than 50°, or more than 40°. By adjusting the inclination to the above-mentioned numerical range, the present invention can further enhance the coating structure and further improve the stability, lifespan, and output performance of the secondary battery.

[0089] In this invention, the average inclination of the slope of the periphery of the closed coating area is obtained by measuring and averaging the inclination at 10 randomly selected locations on a scanning electron microscope (SEM) image of one surface of the positive electrode active material particle. Furthermore, in this invention, any value within the range specified above can be considered to fall within this range.

[0090] As described above, by controlling the coating method and coating morphology, the coating structure can be further strengthened, and the stability, lifespan and output performance of the secondary battery can be further improved.

[0091] According to one aspect of the present invention, the average particle size (D50) of the positive electrode active material particles can be 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, 6 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.

[0092] In this invention, the average diameter (D50) is the particle size at the 50% point of the cumulative area distribution of the particle size, which can be determined using a laser diffraction method. Specifically, after the powder to be tested is dispersed in a dispersion medium, it is introduced into a commercially available laser diffraction particle size analyzer. By measuring the differences in the diffraction patterns produced by the particles based on their size as they pass through the laser beam, the particle size distribution can be calculated.

[0093] On the other hand, the bulk region of the positive electrode active material particles can be particles formed by contact between at least one or more single particles. Here, a single particle refers to a primary particle.

[0094] As a more preferred aspect, the body region may consist of a single particle, or contain 8 or fewer, 7 or fewer, 6 or fewer, 5 or fewer, 4 or fewer, 3 or fewer, or 2 or fewer contacting single particles.

[0095] In one aspect, when the body region is composed of a single particle, the average particle size (D50) can be 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, 6 μm or less, 5.5 μm or less, 5 μm or less, or 4.5 μm or less, and more preferably, it can be composed of a single particle with a particle size of 3.0 μm to 4.0 μm.

[0096] In one aspect, when the body region contains 2 to 8 phase-contacting single particles, it may contain 2 to 8 phase-contacting single particles of 1 μm or larger, 3 μm or smaller, or 2 μm or smaller.

[0097] As one aspect, the aspect ratio (longest major axis / shortest minor axis) of the single particle can be greater than 1, greater than 2, less than 3, less than 2, less than 1.5, less than 1.2, or less than 1.1.

[0098] According to one aspect of the present invention, the positive electrode active material may comprise a plurality of said positive electrode active material particles.

[0099] According to one aspect of the present invention, the positive electrode comprises the positive electrode active material.

[0100] In addition to using the aforementioned positive electrode active material, the positive electrode can have a known structure and be manufactured according to a known manufacturing method. The binder, conductive agent, and solvent are not particularly limited as long as they can be used in the positive electrode current collector of a secondary battery.

[0101] A secondary battery according to one aspect of the present invention comprises the positive electrode active material.

[0102] The secondary battery may specifically include a positive electrode, a negative electrode disposed opposite to the positive electrode, and an electrolyte located between the positive electrode and the negative electrode, but it is not particularly limited as long as it can be used as a secondary battery.

[0103] The embodiments of the present invention will now be described in more detail.

[0104] Manufacturing of positive electrode active materials

[0105] <Manufacturing Examples 1 to 10>

[0106] A lithium complex oxide NiCoMn(OH)2 hydroxide precursor (Ni:Co:Mn = 95:2:3 (at%)) was synthesized using a known co-precipitation method with nickel sulfate, cobalt sulfate, and manganese sulfate.

[0107] LiOH·H2O 1.02 mol%, Al(OH)3 0.5 mol%, ZrO2 0.2 mol%, and Ba(OH)2 0.1 mol were uniformly mixed into the above-prepared precursor, and then heat-treated (first firing) at 800°C to 840°C for 24 hours in a box-shaped sintering furnace with oxygen introduced to produce lithium composite oxide.

[0108] Subsequently, the lithium composite oxide was broken down using a jet mill to produce single-particle lithium composite oxides.

[0109] Next, in an O2 atmosphere at 700°C to 720°C, a positive electrode active material with a particle size of 3μm to 4μm is produced by heat treatment (second firing) in an oxygen atmosphere for 12 hours relative to the lithium composite oxide particles, with Co(OH)2 0.5 to 4.3 mol%, ZrO2 0.2 mol%, and Al2O3 0.5 mol%.

[0110] Manufacturing of lithium secondary batteries

[0111] A positive electrode slurry was prepared by dispersing 96 wt% of the positive electrode active material, 2 wt% of artificial graphite, and 2 wt% of PVDF binder in 8 g of N-methyl-2-pyrrolidone (NMP). The positive electrode slurry was then uniformly coated onto an aluminum film with a thickness of 15 μm and vacuum dried at 135 °C to produce a positive electrode for lithium secondary batteries.

[0112] For the positive electrode, a lithium foil is used as the counter electrode, a porous polyethylene membrane (Celgard 2300, thickness: 25 μm) is used as the separator, and an electrolyte containing LiPF6 at a concentration of 1.15 M is used in a solvent in which ethylene carbonate and methyl ethyl carbonate are mixed in a volume ratio of 3:7 to manufacture a button cell.

[0113] <Experimental Example 1> SEM Analysis

[0114] For the positive electrode active material particles manufactured according to the above example, FE-SEM was used with a JSM-7610FPlus (JEOL) at a voltage of 2kV to obtain particle surface images, which are then shown in... Figure 1 and Figure 2 middle.

[0115] <Experimental Example 2> Coating Area

[0116] The coating area was determined using ImageJ program in a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles, and is shown in Table 1 below.

[0117] <Experimental Example 3> Unit Coating Area and Number of Unit Coating Zones

[0118] In scanning electron microscope (SEM) images of one surface of the positive electrode active material particles, the average area of ​​arbitrarily selected 2 to 5 unit coating areas was determined, as shown in Table 1 below.

[0119] In addition, the number of unit coated areas was determined by scanning electron microscope (SEM) images of all surfaces of the positive electrode active material particles, as shown in Table 1 below.

[0120] <Experimental Example 4> Lifetime Characteristics

[0121] For the lithium secondary battery manufactured according to the above manufacturing example, after 50 charge / discharge cycles at 1C / 1C conditions within a driving voltage range of 2.0V to 4.6V at 25°C, the ratio of the discharge capacity of the 50th cycle to the initial discharge capacity (cycle capacity retention) was measured and is shown in Table 2 below.

[0122] <Experimental Example 5> C-rate determination

[0123] For the lithium secondary battery manufactured according to the above-described manufacturing example, the output efficiency (C-rate) at 1.0C / 0.1C was measured using an electrochemical analysis apparatus (Toyo, Toscat-3100) through a charge-discharge experiment at 25°C, a voltage range of 2.5V to 4.25V, and an applied discharge rate of 0.1C to 1.0C, as shown in Table 2 below.

[0124] [Table 1]

[0125] [Table 2]

Claims

1. A positive electrode active material particle, characterized in that, Includes body region and coating region, The coated area contains cobalt (Co), In a scanning electron microscope (SEM) image of one surface of the positive electrode active material particles, the coating area of ​​the coated region is 83% to 96% relative to the total area of ​​the surface.

2. The positive electrode active material particles according to claim 1, characterized in that, The positive electrode active material particles contain one or more unit coating areas. When the unit coating area refers to a closed coating area on the surface of the bulk region that is not connected to other coating areas, the average area of ​​the unit coating area is 3.0 μm² to 8.0 μm².

3. The positive electrode active material particles according to claim 2, characterized in that, In the positive electrode active material particles, the number of unit coating areas is 1 to 10.

4. The positive electrode active material particles according to claim 2, characterized in that, On the surface of the body region, the average inclination of the slope of the periphery of the closed coating area is less than 70°.

5. The positive electrode active material particles according to claim 1, characterized in that, The average thickness of the coating area, measured vertically from the surface of the body region, is between 20 nm and 60 nm.

6. The positive electrode active material particles according to claim 1, characterized in that, The coating area also contains at least one selected from aluminum (Al), zirconium (Zr), boron (B), tungsten (W), yttrium (Y), and titanium (Ti).

7. The positive electrode active material particles according to claim 1, characterized in that, The body region is doped with at least one element selected from cobalt (Co), zirconium (Zr), barium (Ba), strontium (Sr), aluminum (Al), and titanium (Ti).

8. The positive electrode active material particles according to claim 1, characterized in that, The average particle size (D50) of the positive electrode active material particles is 2.0 μm to 6.0 μm.

9. The positive electrode active material particles according to claim 1, characterized in that, The body region consists of a single particle or contains two to eight contacting single particles.

10. A positive electrode active material, characterized in that, It contains the positive electrode active material particles according to claim 1.

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