LITHIUM COMPLEX OXIDE

Abstract

A lithium complex oxide includes a mixture of first particles of n1 (n1>40) aggregated primary particles and second particles of n2 (n2≤20) aggregated primary particles, the lithium complex oxide represented by Chemical Formula 1 and having FWHM (deg., 2θ) of 104 peak in XRD, defined by a hexagonal lattice having R-3m space group, in a range of Formula 1:

Li.sub.aNi.sub.xCo.sub.yMn.sub.zM.sub.1-x-y-zO.sub.2,   [Chemical Formula 1]

where M is selected from: B, Ba, Ce, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, and any combination thereof, 0.9≤a≤1.3, 0.6≤x≤1.0, 0.0≤y≤=0.4, 0.0≤z≤0.4, and 0.0≤1-x-y-z≤0.4,

−0.025≤FWHM.sub.(104)−{0.04+(x.sub.first particle−0.6)×0.25}≤0.025,   [Formula 1]

where FWHM.sub.(104) is represented by Formula 2,

FWHM.sub.(104)={(FWHM.sub.Chemical Formula 1 powder(104)−0.1×mass ratio of second particles)/mass ratio of first particles}−FWHM.sub.Si powder (220).   [Formula 2]

Claims

1. A lithium complex oxide comprising a mixture of first particles and second particles, wherein an average particle diameter of the first particles is in a range of 8 to 20 μm, wherein an average particle diameter of the second particles is in a range of 0.1 to 7 μm, the lithium complex oxide represented by the following Chemical Formula 1 and having a full width at half maximum (FWHM) (deg., 2θ) of a 104 peak in an XRD peak, defined by a hexagonal lattice having an R-3m space group, in a range of the following Relational Formula 1:
Li.sub.aNi.sub.xCo.sub.yMn.sub.zM.sub.1-x-y-zO.sub.2,   [Chemical Formula 1] wherein in Chemical Formula 1, M is at least one selected from the group consisting of: B, Ba, Ce, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, and any combination thereof, 0.9≤a≤1.3, 0.6≤x≤1.0, 0.0≤y≤=0.4, 0.0≤z≤0.4, and 0.0≤1-x-y-z≤0.4,
−0.025≤FWHM.sub.(104)−{0.04+(x.sub.first particle−0.6)×0.25}≤0.025,   [Relational Formula 1] wherein FWHM.sub.(104) in Relational Formula 1 is represented by the following Relational Formula 2,
FWHM.sub.(104)={(FWHM.sub.Chemical Formula 1 powder(104)−0.1×mass ratio of second particles)/mass ratio of first particles}−FWHM.sub.Si powder (220),   [Relational Formula 2] wherein in Relational Formula 2, FWHM.sub.Chemical Formula 1 powder (104) is a FWHM of a 104 peak observed near 44.5° (2θ) in an XRD measurement value of the lithium complex oxide, FWHM.sub.Si powder (220) is a FWHM of a 220 peak observed near 47.3° (2θ) in an XRD measurement value of a Si powder that is Sigma-Aldrich No. 215619 Si powder, x.sub.first particle=(x−x.sub.second particle*mass ratio of second particles)/mass ratio of first particles, x.sub.second particle meaning a Ni molar rate of the second particles, and x is as defined above in Chemical Formula 1, and the mass ratios mean a mass rate with respect to the total mass of the first particles and the second particles.

2. The lithium complex oxide of claim 1, wherein a crystal structure of the lithium complex oxide is a hexagonal α-NaFeO.sub.2.

3. The lithium complex oxide of claim 1, wherein when a nickel content x is in a range of 0.97 to 0.99, the range of the FWHM.sub.(104) represented by the above Relational Formula 2 satisfies 0.108° (2θ) to 0.162° (2θ).

4. The lithium complex oxide of claim 1, wherein when a nickel content xis in a range of 0.93 to 0.95, the range of FWHM.sub.(104) represented by the above Relational Formula 2 satisfies 0.098° (2θ) to 0.152° (2θ).

5. The lithium complex oxide of claim 1, wherein when a nickel content xis in a range of 0.87 to 0.89, the range of the FWHM.sub.(104) represented by the above Relational Formula 2 satisfies 0.083° (2θ) to 0.137° (2θ).

6. The lithium complex oxide of claim 1, wherein when a nickel content xis in a range of 0.79 to 0.81, the range of the FWHM.sub.(104) represented by the above Relational Formula 2 satisfies 0.063° (2θ) to 0.117° (2θ).

7. A method for preparing the lithium complex oxide of claim 1, the method comprising: preparing a first positive electrode active material by synthesizing a first positive electrode active material precursor including first particles in which n1 (n1>40) number of primary particles are aggregated and then firing the first positive electrode active material precursor after adding a lithium compound to the first positive electrode active material precursor; synthesizing a second positive electrode active material precursor including second particles in which n2 (n2≤20) number of primary particles are aggregated and then firing the second positive electrode active material precursor after adding a lithium compound to the second positive electrode active material precursor; preparing a second positive electrode active material by pulverizing a material formed in the synthesizing and the firing of the second positive electrode active material precursor; mixing the first positive electrode active material and the second positive electrode active material; and coating or doping the mixed material with a material M and then heat-treating the coated or doped material.

8. The method of claim 7, wherein in the adding of the lithium compound to the first positive electrode active material precursor and in the adding of the lithium compound to the second positive electrode active material precursor, the added lithium compound is LiOH.

9. The method of claim 7, wherein an average particle diameter of the first positive electrode active material prepared in the preparing of the first positive electrode active material is in a range of 8 to 20 μm.

10. The method of claim 7, wherein an average particle diameter of the second positive electrode active material prepared in the preparing of the second positive electrode active material is in a range of 0.1 to 7 μm.

11. The method of claim 7, further comprising washing, after firing of the first positive electrode active material precursor, after firing of the second positive electrode active material precursor, or after pulverizing of the material.

12. The method of claim 7, further comprising washing, after heat-treating of the coated or doped material.

13. The method of claim 7, wherein in the coating or doping of the mixed material with the material M, the material M is at least one selected from the group consisting of: B, Ba, Ce, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, and any combination thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] A more complete appreciation of the present invention will become more apparent by describing in detail embodiments thereof with reference to the accompanying drawings, wherein:

[0038] FIG. 1 is an SEM image illustrating a lithium complex oxide according to an embodiment of the present disclosure.

[0039] FIGS. 2 and 3 illustrate results of grain size analysis in terms of a mass mixing ratio between large particles and small particles of a lithium complex oxide according to an embodiment of the present disclosure.

[0040] FIGS. 4 and 5 illustrate graphs comparing battery characteristics of a single-particle-mixed bimodal structure and a multi-particle-mixed bimodal structure.

[0041] FIG. 6 illustrates results of XRD analysis of lithium complex oxides according to Embodiments of the present disclosure and Comparative Examples.

[0042] FIG. 7 illustrates results of XRD analysis of a Si powder according to an embodiment of the present disclosure.

[0043] FIGS. 8 and 9 illustrate graphs comparing battery characteristics of lithium complex oxides according to Embodiments of the present disclosure and Comparative Examples.

[0044] FIGS. 10 and 11 illustrate graphs comparing battery characteristics of lithium complex oxides according to Embodiments of the present disclosure and Comparative Examples.

[0045] FIGS. 12 and 13 illustrate graphs comparing battery characteristics of lithium complex oxides according to Embodiments of the present disclosure and Comparative Examples.

DETAILED DESCRIPTION

[0046] Hereinafter, the present disclosure will be described in more detail with embodiments. However, the present disclosure is not limited by the following embodiments.

[0047] <Measurement Method and Definition of Terms>

[0048] In XRD measurement, a Cu-Kα1 radiation source was used as an X-ray source, and the measurement was performed at 0.02° step intervals in a range of 10 to 70° (2θ) by a θ-2θ scan (Bragg-Brentano parafocusing geometry) method.

[0049] Measurement of FWHM.sub.(104) and FWHM.sub.(220) for a Si powder was calculated by fitting of Gaussian function, and the fitting of Gaussian function for the FWHM measurement may be performed by using various academic/public/commercial softwares known to those skilled in the art.

[0050] A Si powder (product No. 215619) manufactured by Sigma-Aldrich was used as the Si powder.

[0051] A mass mixing ratio between large particles and small particles was identified through grain size analysis, as illustrated in FIGS. 2 and 3.

[0052] The term ‘FWHM range value’ refers to a value of “FWHM.sub.(104)−{0.04+(x−0.6)×0.25}”, and the term ‘FWHM optimal range’ refers to a case where the FWHM value is in a range of −0.025 to 0.025.

[0053] The term FWHM.sub.Large-particle(104)′ refers to a FWHM.sub.(104) value of large particles, the term FWHM.sub.Small-particle(104)′ refers to a FWHM.sub.(104) value of small particles, and the term FWHM.sub.Mixture(104)′ refers to a FWHM.sub.(104) value of a lithium complex oxide prepared by mixing large particles and small particles.

PREPARATION EXAMPLE 1

[0054] A positive electrode active material in which a mole fraction of Ni of multi-particulate large particles (e.g., large particles in the form of multi-particle) was 0.80 and a positive electrode active material in which a mole fraction of Ni of single-particulate small particles (e.g., small particles in the form of single particle) was 0.85 were prepared as follows.

[0055] Synthesizing of Positive Electrode Active Materials Having Large Particles

[0056] After preparing nickel sulfate, cobalt sulfate, and manganese sulfate, a coprecipitation reaction was performed to synthesize a precursor, LiOH was then added to the synthesized precursor, followed by firing, and thus a lithium complex oxide was prepared. Specifically, after mixing LiOH with the precursor, a temperature was raised by 1° C. per minute to perform heat treatment for 10 hours while an O.sub.2 atmosphere was maintained in a firing furnace, and then the heat-treated mixture was naturally cooled, and thus a positive electrode active material was prepared.

[0057] Subsequently, after a distilled water was added to the lithium complex oxide, the lithium complex oxide was washed with the distilled water for 1 hour, the washed lithium complex oxide was then filtered and dried, and thus a positive electrode active material having large particles having an average diameter in a range of 11 to 13 μm was obtained.

[0058] Method of Synthesizing Positive Electrode Active Material Having Single-Particulate Small Particles

[0059] After preparing nickel sulfate, cobalt sulfate, and manganese sulfate, a coprecipitation reaction was performed to synthesize a precursor, LiOH was then added to the synthesized precursor, followed by firing, and thus a lithium complex oxide was prepared. Specifically, after mixing LiOH with the precursor, a temperature was raised to 900° C. by 1° C. per minute to perform heat treatment for 10 hours while an O.sub.2 atmosphere was maintained in a firing furnace, and then the heat-treated mixture was naturally cooled, and thus a positive electrode active material was prepared.

[0060] Subsequently, after the lithium complex oxide was pulverized to a size of 3 to 4 μm using a pulverizer, a distilled water was added to wash the lithium complex oxide for 1 hour, the washed lithium complex oxide was then filtered and dried, and thus a positive electrode active material having single-particulate small particles was obtained.

[0061] Preparing of Final Bimodal Positive Electrode Active Material by Mixing the Large Particles and the Small Particles

[0062] Subsequently, the positive electrode active material having large particles and the positive electrode active material having single-particulate small particles were mixed with a boron (B)-containing raw material (H.sub.3BO.sub.3) using a mixer to perform B coating. The B-containing raw material (H.sub.3BO.sub.3) was mixed in an amount of 0.2% by weight (wt %) with respect to the total weight of the lithium complex oxide. While maintaining an O.sub.2 atmosphere in the same firing furnace, a temperature was raised by 2° C. per minute to perform heat treatment for 5 hours, and then the heat-treated mixture was naturally cooled, and thus a lithium complex oxide was obtained.

[0063] A SEM photograph of the prepared lithium complex oxide was measured and shown in FIG. 1.

<PREPARATION EXAMPLE>PREPARATION OF BATTERY

[0064] A slurry was prepared by mixing the positive electrode active material for a lithium secondary battery prepared according to Preparation Example 1, artificial graphite as a conductive material, and polyvinylidene fluoride (PVdF) as a binder in a weight ratio of 85:10:5. The slurry was uniformly applied to an aluminum foil having a thickness of 15 p.m and vacuum dried at 135° C., and thus a positive electrode for a lithium secondary battery was prepared.

[0065] A coin battery was manufactured in a conventional method using the positive electrode, a lithium foil as a counter electrode, a porous polypropylene film having a thickness of 20 μm as a separator, and an electrolytic solution in which LiPF.sub.6 was dissolved at a concentration of 1.15 M in a solvent in which ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate were mixed in a volume ratio of 3:1:6.

EXPERIMENTAL EXAMPLE 1

[0066] Results of XRD analysis of Embodiments 1-1 to 1-4 and Comparative Examples 1-1 and 1-2 prepared by the preparing method of Preparation Example 1 are illustrated in FIG. 6. It was appreciated that all samples had a hexagonal α-NaFeO.sub.2 (R-3m space group) structure.

[0067] In addition, results of a Si powder analysis with the same XRD equipment and conditions for FWHM correction are illustrated in FIG. 7.

[0068] Next, respective FWHM.sub.(104) values were measured, which are shown in Tables 1 and 2.

TABLE-US-00001 TABLE 1 Multi-particulate large particles Heat- FWHM treatment Li/Metal Molar ratio Large temp. (molar Ni/(Ni + Co/(Ni + Mn/(Ni + particle (° C.) ratio) Co + Mn) Co + Mn) Co + Mn) (104) Embodiment 1-1 790 1.00 0.80 0.10 0.10 0.1579 Embodiment 1-2 780 1.02 0.80 0.10 0.10 0.1644 Embodiment 1-3 780 1.01 0.80 0.09 0.11 0.1779 Embodiment 1-4 770 1.03 0.80 0.10 0.10 0.1869 Comp. Example 1-1 800 1.02 0.80 0.09 0.11 0.1385 Comp. Example 1-2 760 1.01 0.80 0.10 0.10 0.2013

TABLE-US-00002 TABLE 2 Single-particulate small particles Heat- FWHM treatment Li/Metal Molar ratio Small temp. (molar Ni/(Ni + Co/(Ni + Mn/(Ni + particle (° C.) ratio) Co + Mn) Co + Mn) Co + Mn) (104) Embodiment 1-1 900 1.06 0.85 0.11 0.04 0.1044 Embodiment 1-2 900 1.06 0.85 0.11 0.04 0.1044 Embodiment 1-3 900 1.06 0.85 0.11 0.04 0.1044 Embodiment 1-4 900 1.06 0.85 0.11 0.04 0.1044 Comp. Example 1-1 900 1.06 0.85 0.11 0.04 0.1044 Comp. Example 1-2 900 1.06 0.85 0.11 0.04 0.1044

[0069] After a positive electrode active material in which a mole fraction of Ni of large particles was 0.80 and a mole fraction of Ni of small particles, which are single particles, was 0.85 were prepared as in the preparing method of Preparation Example 1, a mass ratio of large particles, a mass ratio of small particles, and FWHM.sub.Mixture(104) according to a mole fraction of Ni were measured to calculate a FWHM range value in accordance with a relational formula of the present disclosure. Next, a battery according to the above Preparation Example was manufactured, and then a discharge capacity and life characteristics were measured, which are shown in Table 3 below and FIGS. 8 and 9.

TABLE-US-00003 TABLE 3 Mixture of multi-particulate large particles + single-particulate small particles Mass ratio Mass ratio FWHM FWHM Discharge Life of large of small Ni/(Ni + B Mixture range capacity @50 cyc particles particles Co + Mn) (ppm) (104) value (mAh/g) (%) Embodiment 1-1 0.6 0.4 0.82 311 0.1341 −0.016 204.9 95.5 Embodiment 1-2 0.7 0.3 0.82 317 0.1455 −0.008 205.6 95.9 Embodiment 1-3 0.8 0.2 0.81 299 0.1644 0.007 206.8 96.2 Embodiment 1-4 0.9 0.1 0.81 305 0.1801 0.016 207.9 96.6 Comp. Example 1-1 0.7 0.3 0.82 309 0.1296 −0.031 205.6 91.9 Comp. Example 1-2 0.7 0.3 0.82 301 0.1708 0.028 199.8 92.8

[0070] Referring to Table 3 and FIGS. 8 and 9, in the case of Embodiments 1-1 to 1-4 in which the FWHM range value satisfies the FWHM optimum range, the discharge capacity and life characteristics of the battery were excellent. However, in the case of Comparative Examples 1-1 to 1-2 in which the FWHM range value does not satisfy the FWHM optimum range, it was appreciated that the discharge capacity and life characteristics of the battery were poor.

PREPARATION EXAMPLE 2

[0071] A positive electrode active material in which a mole fraction of Ni of multi-particulate large particles was 0.88 and a positive electrode active material in which a mole fraction of Ni of single-particulate small particles was 0.88 were prepared

[0072] Synthesizing of Positive Electrode Active Materials Having Large Particles

[0073] After preparing nickel sulfate, cobalt sulfate, and manganese sulfate, a coprecipitation reaction was performed to synthesize a precursor, LiOH was then added to the synthesized precursor, followed by firing, and thus a lithium complex oxide was prepared. Specifically, after mixing LiOH with the precursor, a temperature was raised by 1° C. per minute to perform heat treatment for 10 hours while an O.sub.2 atmosphere was maintained in a firing furnace, and then the heat-treated mixture was naturally cooled, and thus a positive electrode active material having large particles having an average diameter in a range of 11 to 13 μm was obtained.

[0074] Method of Synthesizing Positive Electrode Active Material Having Single-Particulate Small Particles

[0075] After preparing nickel sulfate, cobalt sulfate, and manganese sulfate, a coprecipitation reaction was performed to synthesize a precursor, LiOH was then added to the synthesized precursor, followed by firing, and thus a lithium complex oxide was prepared. Specifically, after mixing LiOH with the precursor, a temperature was raised to 900° C. by 1° C. per minute to perform heat treatment for 10 hours while an 0.sub.2 atmosphere was maintained in a firing furnace, and then the heat-treated mixture was naturally cooled, and thus a positive electrode active material was prepared.

[0076] Subsequently, the lithium complex oxide was pulverized to a size of 3 to 4 μm using a pulverizer, and thus a positive electrode active material having single-particulate small particles was obtained.

[0077] Preparing of Final Bimodal Positive Electrode Active Material by Mixing the Large Particles and the Small Particles

[0078] Subsequently, the positive electrode active material having the multi-particulate large particles and the positive electrode active material having single-particulate small particles were mixed with Al.sub.2O.sub.3 and ZrO.sub.2 using a mixer to perform Al and Zr coating. While maintaining an O.sub.2 atmosphere in the same firing furnace, a temperature was raised by 2° C. per minute to perform heat treatment for 5 hours, and then the heat-treated mixture was naturally cooled.

[0079] Subsequently, a distilled water was added to wash the lithium complex oxide for 1 hour, and the washed lithium complex oxide was then filtered and dried, and thus a lithium complex oxide was obtained.

EXPERIMENTAL EXAMPLE 2

[0080] According to results of XRD analysis of Embodiments 2-1 to 2-4 and Comparative Examples 2-1 and 2-2 prepared by the preparing method of Preparation Example 2, it was appreciated that all samples had a hexagonal α-NaFeO.sub.2 (R-3m space group) structure.

[0081] Next, respective FWHM.sub.(104) values were measured, which are shown in Tables 4 and 5.

TABLE-US-00004 TABLE 4 Multi-particulate large particle Heat- FWHM treatment Li/Metal Molar ratio Large temp. (molar Ni/(Ni + Co/(Ni + Mn/(Ni + particle (° C.) ratio) Co + Mn) Co + Mn) Co + Mn) (104) Embodiment 2-1 740 1.01 0.88 0.09 0.03 0.1738 Embodiment 2-2 730 1.02 0.88 0.09 0.03 0.1816 Embodiment 2-3 720 1.02 0.88 0.08 0.04 0.1943 Embodiment 2-4 710 1.04 0.88 0.09 0.03 0.2043 Comp. Example 2-1 750 1.01 0.88 0.08 0.04 0.1565 Comp. Example 2-2 700 1.04 0.88 0.09 0.03 0.2227

TABLE-US-00005 TABLE 5 Single-particulate small particles Heat- FWHM treatment Li/Metal Molar ratio Small temp. (molar Ni/(Ni + Co/(Ni + Mn/(Ni + particle (° C.) ratio) Co + Mn) Co + Mn) Co + Mn) (104) Embodiment 2-1 900 1.04 0.88 0.10 0.02 0.1029 Embodiment 2-2 900 1.04 0.88 0.10 0.02 0.1029 Embodiment 2-3 900 1.04 0.88 0.10 0.02 0.1029 Embodiment 2-4 900 1.04 0.88 0.10 0.02 0.1029 Comp. Example 2-1 900 1.04 0.88 0.10 0.02 0.1029 Comp. Example 2-2 900 1.04 0.88 0.10 0.02 0.1029

[0082] After a positive electrode active material in which a mole fraction of Ni of large particles was 0.88 and a mole fraction of Ni of small particles, which are single particles, was 0.88 were prepared as in the preparing method of Preparation Example 2, a mass ratio of large particles, a mass ratio of small particles, and FWHM Mixture(104) according to a mole fraction of Ni were measured to calculate a FWHM range value in accordance with a relational formula of the present disclosure. Next, a battery according to the above Preparation Example was manufactured, and then a discharge capacity and life characteristics were measured, which are shown in Table 6 below and FIGS. 10 and 11.

TABLE-US-00006 TABLE 6 Mixture of multi-particulate large particles + single-particulate small particles Mass ratio Mass ratio FWHM FWHM Discharge Life of large of small Ni/(Ni + Al Zr Mixture Range capacity @50 cyc particles particles Co + Mn) (ppm) (ppm) (104) value (mAh/g) (%) Embodiment 2-1 0.6 0.4 0.88 1605 1014 0.1472 −0.014 210.7 94.7 Embodiment 2-2 0.7 0.3 0.88 1592 1101 0.1619 −0.005 213.4 95.5 Embodiment 2-3 0.8 0.2 0.88 1618 998 0.1798 0.007 215.2 95.3 Embodiment 2-4 0.9 0.1 0.88 1585 1016 0.1959 0.014 217.6 94.9 Comp. Example 2-1 0.7 0.3 0.88 1677 1051 0.1401 −0.036 212.4 91.1 Comp. Example 2-2 0.7 0.3 0.88 1628 1121 0.1874 0.032 209.7 90.8

[0083] Referring to Table 6 and FIGS. 10 and 11, in the case of Embodiments 2-1 to 2-4 in which the FWHM range value satisfies the FWHM optimum range, the discharge capacity and life characteristics of the battery were excellent. However, in the case of Comparative Examples 2-1 and 2-2 in which the FWHM range value does not satisfy the FWHM optimum range, it was appreciated that the discharge capacity and life characteristics of the battery were poor.

PREPARATION EXAMPLE 3

[0084] A lithium complex oxide was prepared in the same manner as in Preparation Example 2, except that a mole fraction of Ni of multi-particulate large particles was 0.94, a mole fraction of Ni of single-particulate small particles was 0.92 and Ti and Zr coating was performed.

EXPERIMENTAL EXAMPLE 3

[0085] According to results of XRD analysis of Embodiments 3-1 to 3-4 and Comparative Examples 3-1 and 3-2 prepared by the preparing method of Preparation Example 3, it was appreciated that all samples had a hexagonal α-NaFeO.sub.2 (R-3m space group) structure.

[0086] Next, respective FWHM(104) values were measured, which are shown in Tables 7 and 8.

TABLE-US-00007 TABLE 7 Multi-particulate large particles Heat- FWHM treatment Li/Metal Molar ratio Large temp. (molar Ni/(Ni + Co/(Ni + Mn/(Ni + particle (° C.) ratio) Co + Mn) Co + Mn) Co + Mn) (104) Embodiment 3-1 720 1.03 0.94 0.03 0.03 0.1891 Embodiment 3-2 710 1.00 0.94 0.03 0.03 0.1930 Embodiment 3-3 710 1.03 0.94 0.03 0.03 0.2088 Embodiment 3-4 700 1.02 0.94 0.03 0.03 0.2217 Comp. Example 3-1 730 1.01 0.94 0.03 0.03 0.1643 Comp. Example 3-2 700 1.04 0.94 0.03 0.03 0.2459

TABLE-US-00008 TABLE 8 Single-particulate small particles Heat- FWHM treatment Li/Metal Molar ratio Small temp. (molar Ni/(Ni + Co/(Ni + Mn/(Ni + particle (° C.) ratio) Co + Mn) Co + Mn) Co + Mn) (104) Embodiment 3-1 900 1.05 0.92 0.06 0.02 0.1031 Embodiment 3-2 900 1.05 0.92 0.06 0.02 0.1031 Embodiment 3-3 900 1.05 0.92 0.06 0.02 0.1031 Embodiment 3-4 900 1.05 0.92 0.06 0.02 0.1031 Comp. Example 3-1 900 1.05 0.92 0.06 0.02 0.1031 Comp. Example 3-2 900 1.05 0.92 0.06 0.02 0.1031

[0087] After a positive electrode active material in which a mole fraction of Ni of large particles was 0.94 and a mole fraction of Ni of small particles, which are single particles, was 0.92 were prepared as in the preparing method of Preparation Example 3, a mass ratio of large particles, a mass ratio of small particles, and FWHM.sub.Mixture(104) according to a mole fraction of Ni were measured to calculate a FWHM range value in accordance with a relational formula of the present disclosure. Next, a battery according to the above Preparation Example was manufactured, and then a discharge capacity and life characteristics were measured, which are shown in Table 9 below and FIGS. 12 and 13.

TABLE-US-00009 TABLE 9 Mixture of multi-particulate large particles + single-particulate small particles Mass ratio Mass ratio FWHM FWHM Discharge Life of large of small Ni/(Ni + Ti Zr Mixture range capacity @50 cyc particles particles Co + Mn) (ppm) (ppm) (104) value (mAh/g) (%) Embodiment 3-1 0.6 0.4 0.93 1225 1051 0.1544 −0.017 218.4 93.6 Embodiment 3-2 0.7 0.3 0.93 1210 1036 0.1680 −0.011 220.5 93.5 Embodiment 3-3 0.8 0.2 0.94 1248 1024 0.1892 0.004 223.0 94.1 Embodiment 3-4 0.9 0.1 0.94 1236 1042 0.2151 0.020 224.8 94.6 Comp. Example 3-1 0.7 0.3 0.93 1218 1061 0.1496 −0.037 221.1 88.6 Comp. Example 3-2 0.7 0.3 0.93 1261 1027 0.2038 0.040 219.4 87.8

[0088] Referring to Table 9 and FIGS. 12 and 13, in the case of Embodiments 3-1 to 3-4 in which the FWHM range value satisfies the FWHM optimum range, the discharge capacity and life characteristics of the battery were excellent. However, in the case of Comparative Examples 3-1 and 3-2 in which the FWHM range value does not satisfy the FWHM optimum range, it was appreciated that the discharge capacity and life characteristics of the battery were poor.

<EXPERIMENTAL EXAMPLE 4> COMPARISON OF MULTI-PARTICLE-MIXED BIMODAL AND SINGLE-PARTICLE-MIXED BIMODAL

[0089] In the case of manufacturing a high-nickel NCM bimodal positive electrode active material by mixing small particles with large particles in the form of multi-particle, BET may be reduced, gas generation may be suppressed, and storage characteristics may be improved when small particles in the form of single particle are mixed, as compared to the case where small particles in the form of multi-particle are mixed.

[0090] Rates of gas generation and lifetime characteristics when using the multi-particle-mixed bimodal and when using the single-particle-mixed bimodal were compared, which are shown in Table 10 and FIGS. 4 and 5.

[0091] Referring to FIG. 4, it may be appreciated that a volume change of a pouch cell due to gas generation when left at a high temperature in the case of the multi-particle-mixed bimodal was twice, or more than twice, as large as that in the case of the single-particle-mixed bimodal.

TABLE-US-00010 TABLE 10 Multi-particle-mixed Single-particle-mixed bimodal bimodal Conditions Large particle:Multi- Large particle:Single- particulate small particulate small particles particles Rate 8:2 8:2 PD (g/cc) 3.39 3.50 BET (m.sup.2/g) 1.89 1.46 Coin CH 235.6 237.2 Cell DCH 217.7 216.7 Efficiency 92.4% 91.4% EIS 19.1 19.5 Output (5 C/1 C) 82.4% 83.0% 25° C. Life 93.6% 95.8%
As set forth hereinabove, in the lithium complex oxide according to one or more embodiments of the present disclosure, micro-cracking of the first particles may be inhibited, and accordingly, the life characteristics of the battery including the Ni-rich positive electrode active material are improved by adjusting the range of the FWHM value of the 104 peak defined by a hexagonal lattice having an R-3m space group to maintain a predetermined relationship with the mole fraction of nickel and the mass ratio between the first particles and the second particles.