Method for preparing positive electrode active material

Abstract

Provided is a method for preparing a positive electrode active material, the method comprising the steps of: (A0) preparing nickel oxide by heat-treating nickel hydroxide at a temperature of greater than 400 °C and less than 600 °C; (A) dry-mixing the nickel oxide, a cobalt-containing raw material, and a manganese-containing raw material, and heat-treating the mixture at a temperature of greater than 400 °C and less than 600 °C to prepare a composite transition metal oxide; (B) mixing the composite transition metal oxide and a lithium-containing raw material to prepare a mixture; and (C) calcining the mixture to prepare a lithium composite transition metal oxide.

Description

Method for manufacturing positive electrode active material

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0172676, filed December 1, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a method for manufacturing a positive electrode active material.

[0005]

[0006] With the recent technological development and increasing demand for mobile devices and electric vehicles, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which boast high energy density and voltage, long cycle life, and low self-discharge rates, are commercialized and widely used.

[0007] Lithium transition metal oxides such as lithium cobalt oxide such as LiCoO2, lithium nickel oxide such as LiNiO2, lithium manganese oxide such as LiMnO2 or LiMn2O4, and lithium iron phosphate compounds such as LiFePO4 have been developed as positive electrode active materials for lithium secondary batteries, and recently, Li[Ni a Co b Mn c ]O2, Li[Ni a Co b Al c ]O2, Li[Ni a Co b Mn c Al d ] Lithium composite transition metal oxides containing two or more transition metals, such as O2, have been developed and are widely used.

[0008] In particular, with the recent technological advancements in electric vehicles and other devices, the demand for high-capacity secondary batteries is increasing, and accordingly, research on positive electrodes using high-nickel (High-Ni) positive electrode active materials with excellent capacity characteristics is being actively conducted.

[0009] Known methods for synthesizing these positive electrode active materials include co-precipitation, sol-gel, solid-state synthesis, thermal spray, and combustion.

[0010] The most widely used coprecipitation method involves simultaneously precipitating (co-precipitating) a solution of complex metal components in a reactor to produce a precursor, and then calcining the mixture of the precursor and lithium-containing raw material. In this method, a precipitant such as NH4OH is used depending on the characteristics of the raw metal used, and the pH is controlled to form a precipitate. The rotational force and structure within the reactor cause collisions between particles, producing a precursor in the form of spherical secondary particles in which the primary particles are aggregated. However, if the amount of precipitant used and the control of the reaction environment are uncertain, non-uniform coprecipitation can result in a mixture of precursors with various compositions rather than a single precursor. As a result, the cathode active material produced using this method also has a problem of not having a uniform composition. Furthermore, the coprecipitation method is complex and expensive, making mass production difficult. It also causes environmental problems such as wastewater discharge. In addition, the composition of the cathode active material that can be produced is limited depending on the composition of the precursor.

[0011] On the other hand, in the case of the solid-state synthesis method, the positive electrode active material is manufactured by preparing a mixture powder by mechanically mixing the solid-state raw material powders, then a calcination process that vaporizes and blows away the inorganic substances contained in the mixture powder, and a sintering process that forms an oxide with a uniform composition. In this method, the uniformity, homogeneity, and particle size of the mixture powder have a great influence not only on the sintering characteristics but also on the electrical characteristics, so the control of the raw material powder manufacturing step is important. This solid-state synthesis method has the advantage of being able to mass-produce with a relatively simple synthesis process, and is particularly advantageous for manufacturing lithium composite transition metal oxides with a high nickel content. However, since the solid-state raw material powders are mechanically mixed, there is a limit to uniform mixing, resulting in low uniformity in the composition and particle size of the manufactured positive electrode active material, and difficulty in manufacturing a secondary particle-type material.

[0012] Therefore, there is a need to secure a technology for manufacturing positive electrode active materials with a uniform composition and particle size and various compositions through an environmentally friendly and simple process.

[0013]

[0014] [Prior Art Literature]

[0015] [Patent Document]

[0016] (Patent Document 1) Korean Patent Publication No. 10-2022-0039638

[0017]

[0018] The technical task of the present invention is to provide a method for manufacturing a positive electrode active material having a uniform composition and particle size and having various compositions, using an environmentally friendly and simple process.

[0019]

[0020] (1) The present invention provides a method for producing a cathode active material, comprising the steps of: (A0) heat-treating nickel hydroxide at a temperature of more than 400°C and less than 600°C to produce nickel oxide; (A) dry-mixing the nickel oxide, a cobalt-containing raw material, and a manganese-containing raw material, and heat-treating the same at a temperature of more than 400°C and less than 600°C to produce a composite transition metal oxide; (B) mixing the composite transition metal oxide and a lithium-containing raw material to produce a mixture; and (C) calcining the mixture to produce a lithium composite transition metal oxide.

[0021] (2) The present invention provides a method for manufacturing a positive electrode active material, wherein the heat treatment of step (A) and the heat treatment of step (A0) are performed at the same temperature in the above (1).

[0022] (3) The present invention provides a method for manufacturing a positive electrode active material according to (1) or (2), wherein the nickel oxide has an average crystallite size of 20.0 nm or more and 45.0 nm or less.

[0023] (4) In any one of the above (1) to (3), the nickel oxide has a total pore volume of 0.1200 cm 3 / g or more than 0.1400 cm 3 / g or less. A method for manufacturing a positive electrode active material is provided.

[0024] (5) The present invention provides a method for producing a positive electrode active material according to any one of the above (1) to (4), wherein the nickel oxide has an average pore size of 10,000 nm or more and 30,000 nm or less.

[0025] (6) The present invention relates to a method for producing a positive electrode active material, wherein the nickel oxide has a conversion rate of 90% or more according to the following formula 1, in any one of the above (1) to (5):

[0026] [Formula 1]

[0027]

[0028] The above χ is the value that appears as 100×χ(%) in the TGA data when the weight change (%) is measured while increasing the temperature of nickel oxide from 0℃ to 900℃ at 5-10℃ / min in an air atmosphere using a thermogravimetric analyzer.

[0029] (7) The present invention provides a method for producing a positive electrode active material, wherein the composite transition metal oxide has a nickel content of 80 mol% or more among the total transition metals in any one of (1) to (6).

[0030] (8) The present invention provides a method for producing a positive electrode active material, wherein the composite transition metal oxide is in the form of secondary particles, in any one of (1) to (7).

[0031] (9) The present invention provides a method for producing a positive electrode active material, wherein in any one of the above (1) to (8), the step (B) comprises mixing a composite transition metal oxide and a lithium-containing raw material so that the molar ratio of lithium (Li) to transition metal (M) (Li / M) is 0.95 or more and 1.05 or less to produce a mixture.

[0032] (10) The present invention provides a method for producing a positive electrode active material, wherein in any one of the above (1) to (9), a mixture is produced by further mixing a doping element-containing raw material in the step (B), and the doping element is at least one selected from the group consisting of Al, Y, Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and La.

[0033] (11) The present invention provides a method for producing a positive electrode active material, wherein the calcination is performed in an oxygen atmosphere in any one of the above (1) to (10).

[0034] (12) The present invention provides a method for producing a positive electrode active material, wherein the calcination is performed at a temperature of 700°C or higher and 800°C or lower in any one of the above (1) to (12).

[0035]

[0036] The method for manufacturing a cathode active material of the present invention comprises the steps of dry mixing nickel oxide, cobalt-containing raw material, and manganese-containing raw material produced by heat-treating nickel hydroxide at a specific temperature when manufacturing a lithium composite transition metal oxide, heat-treating at a specific temperature to manufacture a composite transition metal oxide, and mixing and sintering the lithium-containing raw material to manufacture a lithium composite transition metal oxide, thereby increasing the reactivity of the composite transition metal oxide with lithium ions. Accordingly, the effect of suppressing secondary phase formation and cation mixing of the lithium composite transition metal oxide can be implemented. There is an effect of improving the capacity characteristics, rate characteristics, etc. of a cathode and a secondary battery including a cathode active material including the lithium composite transition metal oxide.

[0037] In addition, according to the method for manufacturing a positive electrode active material of the present invention, a positive electrode active material having a uniform composition and particle size and having various compositions can be effectively manufactured.

[0038]

[0039] Figure 1 shows XRD data for each NiO manufactured in Example 1 and Comparative Examples 3 to 6.

[0040] Figure 2 shows TGA data for each NiO manufactured in Example 1 and Comparative Example 3.

[0041] Figure 3 is a SEM image (5K magnification) of the composite transition metal oxide manufactured in Example 1.

[0042] Figure 4 is a cross-sectional SEM image of the composite transition metal oxide manufactured in Comparative Example 7.

[0043] Figure 5 is a SEM image (5K magnification) of the positive electrode active material manufactured in Example 1.

[0044] Figure 6 is a SEM image (20K magnification) of the positive electrode active material manufactured in Example 1.

[0045] Figure 7 is a SEM image (5K magnification) of the positive electrode active material manufactured in Example 2.

[0046] Figure 8 is a cross-sectional SEM image of the positive electrode active material manufactured in Comparative Example 7.

[0047] Figure 9 is a charge / discharge curve of a battery including each of the positive electrode active materials manufactured in Example 1 and Comparative Example 1.

[0048] Figure 10 is a charge / discharge curve of a battery including each of the positive electrode active materials manufactured in Example 2 and Comparative Example 2.

[0049]

[0050] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0051]

[0052] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0053] In this specification, it should be understood that terms such as “include,” “have,” or “have” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0054] In this specification, 'primary particle' means the smallest particle unit recognized when observing a positive electrode active material using a scanning electron microscope (SEM), and 'secondary particle' means a secondary structure formed by the aggregation of multiple primary particles.

[0055] In this specification, the content of each element in the composite transition metal oxide and / or lithium composite transition metal oxide may be measured through ICP (Inductive Coupled Plasma) analysis using an inductively coupled plasma optical emission spectrometer (ICP-OES; Avio series, PerkinElmer).

[0056] In this specification, 'crystallite' means a particle unit having substantially the same crystal orientation.

[0057] In this specification, the 'average crystallite size' can be quantitatively analyzed using X-ray diffraction analysis (XRD) using Cu Kα X-rays. Specifically, the average crystallite size can be quantitatively analyzed by putting the particles to be measured into a holder, irradiating the particles with X-rays, and analyzing the diffraction grating that is generated. Sampling was prepared by putting the powder sample of the particles to be measured into the groove in the center of a general powder holder, smoothing the surface using a slide glass, and ensuring that the sample height is the same as the edge of the holder. Then, X-ray diffraction analysis was performed using a Bruker D8-Endeavor (light source: Cu-Kα rays, wavelength: 1.54Å) equipped with a LynxEye XE-T position sensitive detector, in the range of FDS 0.5°, 2θ=15° to 80°, with a step size of 0.02°, a time per step of 0.2 s, and a total scan time of approximately 11 minutes. For the measured data, Rietveld refinement was performed considering the charge (+3 for metal ions at transition metal sites, +2 for Ni ions at Li sites) and cation mixing at each site. When analyzing the crystallite size, instrumental broadening was considered using the Fundamental Parameter Approach (FPA) implemented in the Bruker TOPAS program, and the entire peaks in the measurement range were used for fitting. The peak shape was fitted using only the Lorenzian contribution as the First Principle (FP) among the peak types available in TOPAS, and strain was not considered at this time.

[0058] In this specification, the 'total pore volume' is obtained by measuring the nitrogen adsorption and desorption amount for a material under vacuum using a surface area measuring device (BELSORP-max II, BEL Japan Co.), and calculating the total pore volume using the BET (Brunaure-Emmett-Teller) method by obtaining an isothermal adsorption-desorption curve.

[0059] In this specification, TGA (Thermo-Gravimetric Analysis) data may be obtained from measuring the weight change of the positive electrode active material using a thermogravimetric analyzer (e.g., TGA2 of Mettler-Toledo).

[0060] In this specification, D min , D 10 , average particle diameter (D 50 ), D 90 , D max In the particle size distribution curve (graph curve of particle size distribution), it can be defined as the particle size corresponding to the minimum, 10%, 50%, 90%, and maximum of the volume cumulative distribution, respectively. The above D min , D 10 , average particle diameter (D 50 ), D 90 , D max The target powder is dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Horiba's LA-960V2), and the particle size distribution is calculated by measuring the difference in diffraction patterns according to particle size when the particles pass through the laser beam, and the particle diameters at the points where the volume cumulative distribution according to particle size in the measuring device is minimum, 10%, 50%, 90%, and maximum are calculated, thereby measuring.

[0061]

[0062] Method for manufacturing positive electrode active material

[0063] Hereinafter, a method for manufacturing a positive electrode active material according to the present invention will be described.

[0064]

[0065] A method for producing a cathode active material according to the present invention comprises the steps of: (A0) heat-treating nickel hydroxide at a temperature of more than 400°C and less than 600°C to produce nickel oxide; (A) dry-mixing the nickel oxide, a cobalt-containing raw material, and a manganese-containing raw material, and heat-treating the same at a temperature of more than 400°C and less than 600°C to produce a composite transition metal oxide; (B) mixing the composite transition metal oxide and a lithium-containing raw material to produce a mixture; and (C) calcining the mixture to produce a lithium composite transition metal oxide.

[0066]

[0067] The present inventors have found that a lithium secondary battery having improved capacity characteristics and rate characteristics can be realized when the lithium secondary battery includes a composite transition metal oxide prepared by dry mixing and heat-treating nickel oxide, cobalt-containing raw materials, and manganese-containing raw materials prepared by heat-treating nickel hydroxide at a specific temperature, and a lithium composite transition metal oxide prepared by mixing and sintering the composite transition metal oxide with a lithium-containing raw material. In addition, the present inventors have found that by controlling the ratio of nickel oxide and cobalt-containing raw materials and manganese-containing raw materials, cathode active materials having various compositions can be prepared through a relatively simple process, and that the cathode active material can be prepared in an environmentally friendly and low-cost manner because no waste liquid or the like is generated during the process, thereby completing the present invention.

[0068]

[0069] Hereinafter, the method for manufacturing a positive electrode active material according to the present invention will be described in more detail.

[0070]

[0071] (A0) Step

[0072] The method for producing a cathode active material according to the present invention includes a step (A0) of producing nickel oxide by heat-treating nickel hydroxide at a temperature of more than 400°C and less than 600°C. Specifically, nickel oxide can be produced by heat-treating nickel hydroxide at a temperature of more than 400°C, 410°C or more, 420°C or more, 430°C or more, 440°C or more, 450°C or more, 460°C or more, 470°C or more, 480°C or more, 490°C or more, or 500°C or more, and 510°C or less, 520°C or less, 530°C or less, 540°C or less, 550°C or less, 560°C or less, 570°C or less, 580°C or less, 590°C or less, or less than 600°C. In this case, the content of residual nickel hydroxide in the manufactured nickel oxide can be suppressed, and the crystallinity and pores of the manufactured nickel oxide can be controlled to increase the reactivity between the composite transition metal oxide and lithium ions. Accordingly, there is an effect of reducing the secondary phase in the lithium composite transition metal oxide manufactured by mixing and firing the composite transition metal oxide and the lithium-containing raw material, and an effect of suppressing cation mixing, so that the capacity and rate characteristics of the secondary battery manufactured with the lithium composite transition metal oxide can be improved. On the other hand, when nickel oxide is manufactured by heat-treating nickel oxide at a temperature of 400°C or lower or 600°C or higher, there is a problem that the conversion rate of the nickel oxide is low. In addition, there is a problem that the reactivity between the composite transition metal oxide manufactured therefrom and lithium ions is low because the crystallinity and pores of the nickel oxide are small or large. Accordingly, there is a problem of excessive secondary phase and excessive cation mixing in the lithium composite transition metal oxide manufactured by mixing and calcining the composite transition metal oxide and lithium-containing raw material.

[0073]

[0074] According to one embodiment of the present invention, the nickel hydroxide has an average particle diameter (D 50) may be 5.0 ㎛ or more and 20.0 ㎛ or less. Specifically, it may be 5.0 ㎛ or more, 6.0 ㎛ or more, 7.0 ㎛ or more, 8.0 ㎛ or more, 9.0 ㎛ or more, 10.0 ㎛ or more, 11.0 ㎛ or more, 12.0 ㎛ or more, 13.0 ㎛ or more, or 14.0 ㎛ or more, and may be 15.0 ㎛ or less, 16.0 ㎛ or less, 17.0 ㎛ or less, 18.0 ㎛ or less, 19.0 ㎛ or less, or 20.0 ㎛ or less. The average particle diameter (D 50 ) is within the above range, the capacity and rate characteristics of the secondary battery manufactured with the finally manufactured lithium composite transition metal oxide can be improved.

[0075]

[0076] (A) Step

[0077] The method for manufacturing a positive electrode active material according to the present invention includes step (A) of dry mixing the nickel oxide, cobalt-containing raw material, and manganese-containing raw material manufactured in step (A0) and heat-treating them at a temperature exceeding 400°C and less than 600°C to manufacture a composite transition metal oxide.

[0078]

[0079] The composite transition metal oxide of the present invention is manufactured by dry-mixing a mixture of solid-state raw material powders mechanically mixed and then heat-treating the mixture. In this case, there is an advantage in that a desired material can be mass-produced through a relatively simple synthesis process.

[0080] When nickel oxide, cobalt-containing raw material, and manganese-containing raw material heat-treated at a specific temperature as in the present invention are dry-mixed and heat-treated, the crystallinity and pores of the composite transition metal oxide can be controlled, thereby increasing the reactivity of the composite transition metal oxide with lithium ions. Accordingly, there is an effect of reducing secondary phases and suppressing cation mixing in the lithium composite transition metal oxide produced by mixing and firing the composite transition metal oxide and the lithium-containing raw material.

[0081] On the other hand, when using the co-precipitation method to manufacture composite transition metal hydroxides, which are precursors of lithium composite transition metal oxides, there are problems such as high process costs due to the complex process and environmental problems such as wastewater generation, and the composition of lithium composite transition metal oxides that can be manufactured is limited depending on the composition of the precursor. When using the solid-state synthesis method to manufacture lithium composite transition metal oxides using a solid-state raw material mixture without a precursor of lithium composite transition metal oxides, there are problems such as difficulty in controlling the particle size of lithium composite transition metal oxides and difficulty in manufacturing secondary particle-type counterparts.

[0082] In addition, when nickel nitrate, nickel sulfate, nickel carbonate, etc., rather than nickel oxide, is used as a nickel-containing raw material, there is a problem that it is difficult to control the particle size of the lithium composite transition metal oxide and it is difficult to manufacture a cathode active material in the form of secondary particles.

[0083]

[0084] When selecting raw materials for manganese-containing raw materials and cobalt-containing raw materials, any raw materials applicable to dry mixing may be used without limitation. However, since residual sulfur after synthesis may cause problems for the positive electrode active material and heat treatment equipment, it is preferable to exclude sulfate-based compounds. Specifically, nitrate, oxide, carbonate, and hydroxide-based compounds may be used. Specifically, considering the ease of manufacturing processes such as particle size control and doping, Mn(NO3)2 may be used as the manganese-containing raw material, and Co(NO3)2 may be used as the cobalt-containing raw material.

[0085]

[0086] According to the present invention, the heat treatment of step (A) is performed at a temperature of more than 400°C and less than 600°C. Specifically, the heat treatment is performed at a temperature of more than 400°C, 410°C or more, 420°C or more, 430°C or more, 440°C or more, 450°C or more, 460°C or more, 470°C or more, 480°C or more, 490°C or more, or 500°C or more, and 510°C or less, 520°C or less, 530°C or less, 540°C or less, 550°C or less, 560°C or less, 570°C or less, 580°C or less, 590°C or less, or less than 600°C. When the heat treatment is within the above range, sufficient heat energy can be supplied for the nickel oxide, cobalt-containing raw material, and manganese-containing raw material to react, and the crystallinity and pores of the composite transition metal oxide can be controlled, so that when manufacturing a lithium composite transition metal oxide, the reactivity between the composite transition metal oxide and lithium ions can be increased. When the heat treatment is 400°C or lower, sufficient heat energy is not supplied for the nickel oxide, cobalt-containing raw material, and manganese-containing raw material to react, so that there is a problem that cobalt and manganese are not contained in an appropriate amount in the manufactured composite transition metal oxide. When the heat treatment is 600°C or higher, the crystallinity of the composite transition metal oxide increases, so that there is a problem that the reactivity of lithium ions decreases when manufacturing a lithium composite transition metal oxide.

[0087]

[0088] According to one embodiment of the present invention, the heat treatment of step (A) and the heat treatment of step (A0) may be performed at the same temperature. In this case, by controlling the residual nickel hydroxide content and crystallinity, a composite transition metal oxide having a low residual nickel hydroxide content, appropriate levels of cobalt and manganese, and improved reactivity can be produced.

[0089]

[0090] According to one embodiment of the present invention, the nickel oxide may have an average crystallite size of 20.0 nm or more and 45.0 nm or less. Specifically, the average crystallite size may be 20.0 nm or more, 21.0 nm or more, 22.0 nm or more, 23.0 nm or more, 24.0 nm or more, 25.0 nm or more, 26.0 nm or more, 27.0 nm or more, 28.0 nm or more, 29.0 nm or more, 30.0 nm or more, 31.0 nm or more, 32.0 nm or more, 33.0 nm or more, 34.0 nm or more, 35.0 nm or more, 36.0 nm or more, 37.0 nm or more, 38.0 nm or more, or 39.0 nm or more, and may be 40.0 nm or less, 41.0 nm or less, 42.0 nm or less, 43.0 nm or less, 44.0 nm or less, or 45.0 nm or less. When the average crystallite size is within the above range, the residual nickel hydroxide content of the composite transition metal oxide can be suppressed, and the reactivity between the composite transition metal oxide and lithium ions can be increased. Accordingly, there is an effect of reducing secondary phases and suppressing cation mixing in the lithium composite transition metal oxide manufactured by mixing and firing the composite transition metal oxide and the lithium-containing raw material, thereby improving the discharge capacity of a secondary battery manufactured with the lithium composite transition metal oxide.

[0091]

[0092] According to one embodiment of the present invention, the nickel oxide has a total pore volume of 0.1200 cm 3 / g or more than 0.1400 cm 3 / g or less. Specifically, the total pore volume is 0.1200 cm 3 / g or more, 0.1210 cm 3 / g or less, 0.1220 cm 3 / g or less, 0.1230 cm 3 / g or less, 0.1240 cm 3 / g or less, 0.1250 cm 3 / g or less, 0.1260 cm 3 / g or less, 0.1270 cm 3 / g or less, 0.1280 cm 3 / g or less, 0.1290 cm 3 / g or less, 0.1300 cm 3 / g or less, 0.1310 cm 3 / g or less, 0.1320 cm 3 / g or less, 0.1330 cm 3 / g or less, 0.1340 cm 3 / g or less, 0.1350 cm 3 / g or less, 0.1360 cm 3 / g or less, 0.1370 cm 3 / g or less, 0.1380 cm 3 / g or less, 0.1390 ​​cm 3 / g or less, or 0.1400 cm 3 / g or less. When the total pore volume is within the above range, metal ions such as manganese and cobalt are appropriately diffused into nickel oxide to form a composite transition metal oxide, and when the composite transition metal oxide and the lithium-containing raw material are mixed and fired, lithium ions are appropriately diffused to produce a lithium composite transition metal oxide. The lithium composite transition metal oxide has a layered structure, secondary phases are reduced, and cation mixing is suppressed, so that the capacity characteristics of a secondary battery produced therefrom can be improved.

[0093]

[0094] According to one embodiment of the present invention, the nickel oxide may have an average pore size of 10,000 nm or more and 30,000 nm or less. Specifically, the average pore size may be 10.000 nm or more, 11.000 nm or more, 12.000 nm or more, 13.000 nm or more, or 14.000 nm or more, 15.000 nm or less, 16.000 nm or less, 17.000 nm or less, 18.000 nm or less, 19.000 nm or less, 20.000 nm or less, 21.000 nm or less, 22.000 nm or less, 23.000 nm or less, 24.000 nm or less, 25.000 nm or less, 26.000 nm or less, 27.000 nm or less, 28.000 nm or less, 29.000 nm or less, or 30.000 nm or less. When the average pore size is within the above range, metal ions such as manganese and cobalt are appropriately diffused into nickel oxide to form a composite transition metal oxide, and when the composite transition metal oxide and the lithium-containing raw material are mixed and fired, lithium ions are appropriately diffused to produce a lithium composite transition metal oxide having a uniform composition. The lithium composite transition metal oxide has a layered structure, secondary phases are reduced, and cation mixing is suppressed, so that the capacity characteristics of a secondary battery produced therefrom can be improved.

[0095]

[0096] According to one embodiment of the present invention, the nickel oxide may have a conversion rate of 90% or more according to the following equation 1.

[0097] [Formula 1]

[0098]

[0099] The above χ is the value that appears as 100×χ(%) in the TGA data when the weight change (%) is measured while increasing the temperature of nickel oxide from 0℃ to 900℃ at 5-10℃ / min in an air atmosphere using a thermogravimetric analyzer.

[0100] Specifically, the conversion rate according to the above formula 1 may be 90% or more, and may be 91% or less, 92% or less, 93% or less, 94% or less, 95% or less, 96% or less, 97% or less, 98% or less, 99% or less, or 100% or less. The closer the conversion rate according to the above formula 1 is to 100%, the closer χ, which represents the weight change when heat-treated using a thermogravimetric analyzer, is to 0, which means that there is no residual nickel hydroxide in the nickel oxide, and that when nickel hydroxide is heat-treated to manufacture nickel oxide, all of the nickel hydroxide has become nickel oxide. When the conversion rate is within the above range, a composite transition metal oxide having a uniform composition can be manufactured by controlling the reaction of a cobalt-containing raw material and a manganese-containing raw material. Specifically, secondary phases resulting from the abnormal reaction of nickel hydroxide, which is more reactive than nickel oxide, with cobalt-containing raw materials and manganese-containing raw materials are reduced, so that a composite transition metal oxide having a uniform composition can be manufactured.

[0101]

[0102] According to one embodiment of the present invention, the composite transition metal oxide may have a nickel content of 80 mol% or more among the total transition metals. Specifically, the nickel content of the total transition metals may be 80 mol% or more, 81 mol% or more, 82 mol% or more, 83 mol% or more, 84 mol% or more, 85 mol% or more, 86 mol% or more, 87 mol% or more, 88 mol% or more, or 90 mol% or more, and may be 95 mol% or less, 96 mol% or less, 97 mol% or less, 98 mol% or less, or 99 mol% or less. When the nickel content is within the above range, a cathode active material exhibiting high energy density and having high-capacity characteristics can be produced. In particular, when the nickel content is 88 mol% or more and 95 mol% or less, cathode active materials having various compositions can be easily produced from a single raw material, nickel oxide.

[0103]

[0104] According to one embodiment of the present invention, the composite transition metal oxide may be in the form of secondary particles. In this case, the energy density can be increased, thereby improving the capacity characteristics of a battery comprising the lithium composite transition metal oxide manufactured therefrom.

[0105]

[0106] According to one embodiment of the present invention, the composite transition metal oxide has an average particle diameter (D 50 ) may be 7㎛ or more and 25㎛ or less. Specifically, the composite transition metal oxide has an average particle diameter (D 50 ) may be 7.0 ㎛ or more, 8.0 ㎛ or more, 9.0 ㎛ or more, 10.0 ㎛ or more, 11.0 ㎛ or more, 12.0 ㎛ or more, 13.0 ㎛ or more, 14.0 ㎛ or more, 15.0 ㎛ or more, 16.0 ㎛ or more, 17.0 ㎛ or more, 18.0 ㎛ or more, or 19.0 ㎛ or more, and may be 20.0 ㎛ or less, 21.0 ㎛ or less, 22.0 ㎛ or less, 23.0 ㎛ or less, 24.0 ㎛ or less, or 25.0 ㎛ or less. The average particle diameter (D 50 ) is within the above range, the capacity and rate characteristics of the secondary battery manufactured with the finally manufactured lithium composite transition metal oxide can be improved.

[0107]

[0108] (B) Step

[0109] The method for manufacturing a positive electrode active material according to the present invention includes, after step (A), step (B) of manufacturing a mixture by mixing the composite transition metal oxide and a lithium-containing raw material.

[0110]

[0111] Examples of the lithium-containing raw material include lithium-containing carbonates (e.g., lithium carbonate, etc.), hydrates (e.g., lithium hydroxide hydrate (LiOH H2O)), hydroxides (e.g., lithium hydroxide, etc.), nitrates (e.g., lithium nitrate (LiNO3)), chlorides (e.g., lithium chloride (LiCl)), etc., and one of these may be used alone or a mixture of two or more thereof. Specifically, LiOH H2O may be used when considering economic feasibility and ease of manufacturing process due to its low cost and low melting point.

[0112]

[0113] According to one embodiment of the present invention, the step (B) may be to prepare a mixture by mixing the composite transition metal oxide and the lithium-containing raw material so that the molar ratio of lithium (Li) to the transition metal (M) (Li / M) is 0.95 or more and 1.05 or less. Specifically, the molar ratio of lithium (Li) contained in the lithium-containing raw material to the transition metal (M) contained in the composite transition metal oxide may be 0.95 or more, 0.96 or more, 0.97 or more, 0.98 or more, 0.99 or more, 1.00 or more, 1.01 or more, or 1.02 or more, and 1.03 or less, 1.04 or less, or 1.05 or less. When the molar ratio of lithium (Li) to the transition metal (M) (Li / M) is mixed so that it is within the above range, a lithium composite transition metal oxide having a uniform composition can be prepared while minimizing residual lithium.

[0114]

[0115] According to one embodiment of the present invention, in the step (B), a mixture is prepared by further mixing a doping element-containing raw material, and the doping element may be at least one selected from the group consisting of Al, Y, Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and La. The doping element-containing raw material is not necessarily included, but when included in an appropriate amount, the grain shape of the positive electrode active material may be improved, and the stability of the crystal structure may be enhanced.

[0116]

[0117] (C) Step

[0118] The method for manufacturing a positive electrode active material according to the present invention includes, after step (B), step (C) of calcining the mixture to manufacture a lithium composite transition metal oxide.

[0119]

[0120] According to one embodiment of the present invention, in step (C), the calcination may be performed under an oxygen atmosphere. In this case, the reaction between the composite transition metal oxide and the lithium-containing raw material is promoted, thereby efficiently growing lithium composite transition metal oxide particles.

[0121]

[0122] According to one embodiment of the present invention, in the step (C), the sintering may be performed at a temperature of 700°C or more and 800°C or less. Specifically, it may be performed at a temperature of 700°C or more, 710°C or more, 720°C or more, 730°C or more, 740°C or more, or 750°C or more, and 760°C or less, 770°C or less, 780°C or less, 790°C or less, or 800°C or less. Within the above temperature range, a lithium composite transition metal oxide in the form of secondary particles can be formed. When the lithium composite transition metal is in the form of secondary particles, the energy density is improved, thereby improving the capacity characteristics of a battery manufactured therefrom.

[0123]

[0124] positive electrode active material

[0125] In addition, the present invention provides a positive electrode active material manufactured by the manufacturing method described above.

[0126] The cathode active material according to the present invention is manufactured by the manufacturing method described above, and includes a lithium composite transition metal oxide in the form of secondary particles in which the particle size and particle shape are maintained similar to those of the spherical nickel hydroxide as the raw material, and the formation of secondary phases and mixing of cations are suppressed.

[0127]

[0128] According to one embodiment of the present invention, the positive electrode active material has an average particle diameter (D 50 ) is 10.0㎛ or more and 25.0㎛ or less, and the span value according to the following formula 2 may be 0.70 or more and 2.00 or less.

[0129] [Formula 2]

[0130]

[0131] Specifically, the positive electrode active material has an average particle diameter (D 50) may be 10.0㎛ or more, 11.0㎛ or more, 12.0㎛ or more, 13.0㎛ or more, or 14.0㎛ or more, or 15.0㎛ or less, 16.0㎛ or less, 17.0㎛ or less, 18.0㎛ or less, 19.0㎛ or less, 20.0㎛ or less, 21.0㎛ or less, 22.0㎛ or less, 23.0㎛ or less, 24.0㎛ or less, or 25.0㎛ or less, and the span value according to the above formula 2 may be 0.70 or more, or 0.80 or more, or 0.90 or less, 1.00 or less, 1.10 or less, 1.20 or less, 1.30 or less, 1.40 or less, 1.50 or less, 1.60 or less, 1.70 or less, 1.80 or less, It may be 1.90 or less, or 2.00 or less. The above average particle diameter (D 50 ) and when the span value according to the above formula 2 is within the above range, there is an effect of improving the capacity characteristics, rate characteristics, etc. of the positive electrode and secondary battery including the positive electrode active material.

[0132]

[0133] According to one embodiment of the present invention, the positive electrode active material may include a lithium composite transition metal oxide having a composition represented by the following chemical formula 1.

[0134] [Chemical Formula 1]

[0135] Li 1+x Ni a Co b Mn c M 1 d O2

[0136] In the above chemical formula 1, the M 1 is at least one selected from Zr, Y, W, Cu, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al, and 0.000≤x≤0.100, 0.60≤a<1.00, 0 <b≤0.40, 0<c≤0.40, 0≤d≤0.10, a+b+c+d=1이다.

[0137] Above M 1is a doping element, specifically the above M 1 M may be at least one selected from Zr, Y, W, Cu, Sr, Mn, Y, Ti, Mg, Mo, B, Sn, Fe, Zn, Si and Al. 1 Although it is not essential, if included in an appropriate amount, the particle shape of the positive electrode active material can be improved and the stability of the crystal structure can be enhanced.

[0138] Meanwhile, the above x may be 0.000 or more, or 0.010 or more, and may be 0.020 or less, 0.030 or less, 0.040 or less, 0.050 or less, 0.060 or less, 0.070 or less, 0.080 or less, 0.090 or less, or 0.100 or less. When x satisfies the above range, high-capacity characteristics and high energy density per unit volume can be realized.

[0139] The above a is the molar fraction of nickel (Ni) among the total metals excluding lithium in the lithium composite transition metal oxide, and may be 0.60 or more, 0.70 or more, 0.80 or more, 0.85 or more, 0.86 or more, 0.87 or more, 0.88 or more, or 0.89 or more, and may be 0.95 or less, 0.96 or less, 0.97 or less, 0.98 or less, 0.99 or less, or less than 1.00. When a is within the above range, a high energy density is exhibited, so that high-capacity characteristics can be realized. In particular, when a is 0.88 or more and 0.95 or less, there is an effect of improving the capacity characteristics, rate characteristics, etc. of the positive electrode and the secondary battery including the positive electrode active material.

[0140] The above b is the mole fraction of cobalt (Co) among the total metals excluding lithium in the lithium composite transition metal oxide, and may be 0 or more, 0.01 or more, 0.02 or more, or 0.03 or more, and may be 0.05 or less, 0.10 or less, 0.20 or less, 0.25 or less, 0.30 or less, 0.35 or less, or 0.40 or less. When b satisfies the above range, the output characteristics can be improved during the charge and discharge process.

[0141] The above c is the mole fraction of manganese (Mn) among the total metals excluding lithium in the lithium composite transition metal oxide, and may be 0.01 or more, 0.02 or more, 0.03 or more, or 0.04 or more, and may be 0.07 or less, 0.10 or less, 0.15 or less, 0.20 or less, 0.25 or less, 0.30 or less, 0.35 or less, or 0.40 or less. When c satisfies the above range, high-temperature stability increases, and the decomposition reaction of the electrolyte may be relatively reduced.

[0142] The above d is M of all metals except lithium in the lithium composite transition metal oxide. 1 The mole fraction of d may be 0 or more, 0.01 or more, 0.02 or more, or 0.03 or more, and may be 0.04 or less, 0.05 or less, 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, or 0.10 or less. When d satisfies the above range, the stability of the crystal structure of the positive electrode active material may be improved and the particle shape may be improved.

[0143]

[0144] anode

[0145] In addition, the present invention provides a positive electrode for a lithium secondary battery including the positive electrode active material described above.

[0146] Specifically, the positive electrode includes a positive electrode current collector, and a positive electrode active material layer positioned on at least one surface of the positive electrode current collector and including the positive electrode active material described above.

[0147] The positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 μm, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesive strength of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0148]

[0149] The above positive electrode active material layer may include a conductive material and a binder together with the positive electrode active material.

[0150] At this time, the positive electrode active material may be included in an amount of 80 to 99 wt%, more specifically 85 to 98 wt%, based on the total weight of the positive electrode active material layer. When included in the above content range, excellent capacity characteristics can be exhibited.

[0151] At this time, the conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like, and one type alone or a mixture of two or more types thereof may be used. The conductive material may be included in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0152]

[0153] The above binder serves to improve the adhesion between positive electrode active material particles and the adhesive strength between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The binder may be included in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0154]

[0155] The above-mentioned positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the above-mentioned positive electrode active material is used. Specifically, the positive electrode composite material, prepared by dissolving or dispersing the above-mentioned positive electrode active material and optionally a binder and a conductive agent in a solvent, is applied onto a positive electrode current collector, and then dried and rolled. At this time, the types and contents of the positive electrode active material, binder, and conductive agent are as described above.

[0156]

[0157] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, taking into account the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0158]

[0159] Alternatively, the positive electrode may be manufactured by casting the positive electrode composite on a separate support, then peeling the resulting film from the support and laminating it on a positive electrode current collector.

[0160]

[0161] lithium secondary battery

[0162] In addition, the present invention can manufacture an electrochemical device including the positive electrode. The electrochemical device may be a battery, a capacitor, or the like, and more specifically, a lithium secondary battery.

[0163] The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, and a separator and electrolyte interposed between the positive electrode and the negative electrode. Since the positive electrode is the same as described above, a detailed description thereof will be omitted, and only the remaining components will be described in detail below.

[0164] In addition, the lithium secondary battery may optionally further include a battery container that houses the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0165]

[0166] In the above lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0167] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 ㎛ to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0168]

[0169] The above negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0170] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO β(0<β<2), SnO2, vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical, or fiber-like forms, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes.

[0171] The above negative electrode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0172]

[0173] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and can typically be added in an amount of 0.1 wt% to 10 wt% based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0174] The conductive agent is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10 wt% or less, preferably 5 wt% or less, based on the total weight of the negative electrode active material layer. The conductive agent is not particularly limited as long as it has conductivity and does not cause a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber or metal fiber; fluorinated carbon; metal powder such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0175]

[0176] The above negative electrode active material layer can be manufactured by applying and drying a negative electrode composite prepared by dissolving or dispersing a negative electrode active material, and optionally a binder and a conductive material in a solvent, on a negative electrode current collector, or by casting the negative electrode composite on a separate support and then laminating the obtained film by peeling it off from the support on a negative electrode current collector.

[0177]

[0178] Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without special restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture absorption capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, can be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. can also be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength can be used, and can optionally be used in a single-layer or multi-layer structure.

[0179]

[0180] In addition, examples of the electrolyte used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0181] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0182] As the organic solvent, any solvent that can serve as a medium through which ions involved in the electrochemical reaction of the battery can move may be used without particular limitation. Specifically, the organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); Alcohol solvents such as ethyl alcohol, isopropyl alcohol, etc.; nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes, etc. can be used. Among these, carbonate solvents are preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of a battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferable.

[0183] The above lithium salt can be used without any special limitation as long as it is a compound that can provide lithium ions used in a lithium secondary battery. Specifically, the above lithium salt is LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2) 2. LiCl, LiI, or LiB(C2O4)2 can be used. The concentration of the lithium salt is preferably within the range of 0.1 to 4.0 M, and preferably, 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0184]

[0185] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the total weight of the electrolyte.

[0186]

[0187] As described above, a lithium secondary battery including a cathode active material according to the present invention stably exhibits excellent discharge capacity, rate characteristics, etc., and is therefore useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0188] Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0189] The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0190] There is no particular limitation on the external shape of the lithium secondary battery of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0191] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also be preferably used as a unit battery in a medium- to large-sized battery module including a plurality of battery cells.

[0192]

[0193] Hereinafter, the present invention will be described in detail with reference to examples. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention should not be construed as being limited to the examples described below. The examples of the present invention are provided to more fully explain the present invention to those of ordinary skill in the art.

[0194]

[0195] Examples and Comparative Examples

[0196] Example 1

[0197] Nickel hydroxide (D) is a spherical, porous, and has a composition represented by Ni(OH)2. 50 : 14.4㎛, secondary particle form) was heat treated at 500℃ in an air atmosphere for 6 hours to produce NiO.

[0198] The above NiO and Co(NO3)2 and Mn(NO3)2 were dry mixed so that the molar ratio of Ni:Co:Mn was 95:2:3, and heat-treated for 6 hours under an air atmosphere and a temperature of 500℃ to obtain Ni 0.95 Co 0.02 Mn 0.03 A complex transition metal oxide having a composition represented by O was prepared.

[0199] The above complex transition metal oxide (composition: Ni) 0.95 Co 0.02 Mn 0.03 O) and LiOHH2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.03, and calcined at 760℃ in an oxygen atmosphere for 13 hours, Li 1.073 Ni 0.95 Co 0.02 Mn 0.03 A lithium composite transition metal oxide (positive electrode active material) having a composition represented by O2 was prepared. Subsequently, it was classified into sizes of 38 μm or less.

[0200]

[0201] Example 2

[0202] Nickel hydroxide (D) is a spherical, porous, and has a composition represented by Ni(OH)2. 50 : 14.4㎛, secondary particle form) was heat treated at 500℃ in an air atmosphere for 6 hours to produce NiO.

[0203] The above NiO and Co(NO3)2 and Mn(NO3)2 were dry mixed so that the molar ratio of Ni:Co:Mn was 88:5:7, and heat-treated for 6 hours under an air atmosphere and a temperature of 500℃ to obtain Ni 0.88 Co 0.05 Mn 0.07 A complex transition metal oxide having a composition represented by O was prepared.

[0204] The above complex transition metal oxide (composition: Ni) 0.88 Co 0.05 Mn 0.07 O) and LiOHH2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.03, and calcined at 760℃ in an oxygen atmosphere for 13 hours, Li 1.065 Ni 0.88 Co 0.05 Mn 0.07 A lithium composite transition metal oxide (positive electrode active material) having a composition represented by O2 was prepared. Subsequently, it was classified into sizes of 38 μm or less.

[0205]

[0206] Comparative Example 1

[0207] Ni 0.95 Co 0.02 Mn 0.03 Complex transition metal hydroxides (D) having a composition represented by (OH)2 50 : 7.6㎛, secondary particle form) and LiOHH2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.03, and calcined at 760°C in an oxygen atmosphere for 13 hours to produce a lithium composite transition metal oxide (positive electrode active material).

[0208]

[0209] Comparative Example 2

[0210] Ni 0.88 Co 0.05 Mn 0.07 Complex transition metal hydroxides (D) having a composition represented by (OH)2 50: 12.0㎛, secondary particle form) and LiOHH2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.03, and calcined at 760°C in an oxygen atmosphere for 13 hours to manufacture a lithium composite transition metal oxide (positive electrode active material).

[0211]

[0212] Comparative Example 3

[0213] Nickel hydroxide (D) is a spherical, porous, and has a composition represented by Ni(OH)2. 50 : 14.4㎛, secondary particle form) was heat treated at 400℃ in an air atmosphere for 6 hours to produce NiO.

[0214] The above NiO and Co(NO3)2 and Mn(NO3)2 were dry mixed so that the molar ratio of Ni:Co:Mn was 95:2:3, and heat-treated for 6 hours under an air atmosphere and a temperature of 400℃ to obtain Ni 0.95 Co 0.02 Mn 0.03 A complex transition metal oxide having a composition represented by O was prepared.

[0215] The above complex transition metal oxide (composition: Ni) 0.95 Co 0.02 Mn 0.03 O) and LiOHH2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.03, and calcined in an oxygen atmosphere at 760°C for 13 hours to produce a lithium composite transition metal oxide (positive electrode active material).

[0216]

[0217] Comparative Example 4

[0218] Nickel hydroxide (D) is a spherical, porous, and has a composition represented by Ni(OH)2. 50 : 14.4㎛, secondary particle form) was heat treated at 600℃ in an air atmosphere for 6 hours to produce NiO.

[0219] The above NiO and Co(NO3)2 and Mn(NO3)2 were dry mixed so that the molar ratio of Ni:Co:Mn was 95:2:3, and heat-treated for 6 hours under an air atmosphere and a temperature of 600℃ to obtain Ni 0.95 Co 0.02 Mn 0.03 A complex transition metal oxide having a composition represented by O was prepared.

[0220] The above complex transition metal oxide (composition: Ni) 0.95 Co 0.02 Mn 0.03 O) and LiOHH2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.03, and calcined in an oxygen atmosphere at 760°C for 13 hours to produce a lithium composite transition metal oxide (positive electrode active material).

[0221]

[0222] Comparative Example 5

[0223] Nickel hydroxide (D) is a spherical, porous, and has a composition represented by Ni(OH)2. 50 : 14.4㎛, secondary particle form) was heat treated at 650℃ in an air atmosphere for 6 hours to produce NiO.

[0224] The above NiO and Co(NO3)2 and Mn(NO3)2 were dry mixed so that the molar ratio of Ni:Co:Mn was 95:2:3, and heat-treated for 6 hours under an air atmosphere and a temperature of 650℃ to obtain Ni 0.95 Co 0.02 Mn 0.03 A complex transition metal oxide having a composition represented by O was prepared.

[0225] The above complex transition metal oxide (composition: Ni) 0.95 Co 0.02 Mn 0.03 O) and LiOHH2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.03, and calcined in an oxygen atmosphere at 760°C for 13 hours to produce a lithium composite transition metal oxide (positive electrode active material).

[0226]

[0227] Comparative Example 6

[0228] Nickel hydroxide (D) is a spherical, porous, and has a composition represented by Ni(OH)2. 50 : 14.4㎛, secondary particle form) was heat treated at 750℃ in an air atmosphere for 6 hours to produce NiO.

[0229] The above NiO and Co(NO3)2 and Mn(NO3)2 were dry mixed so that the molar ratio of Ni:Co:Mn was 95:2:3, and heat-treated for 6 hours under an air atmosphere and a temperature of 750℃ to obtain Ni 0.95 Co 0.02 Mn 0.03 A complex transition metal oxide having a composition represented by O was prepared.

[0230] The above complex transition metal oxide (composition: Ni) 0.95 Co 0.02 Mn 0.03 O) and LiOHH2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.03, and calcined in an oxygen atmosphere at 760°C for 13 hours to produce a lithium composite transition metal oxide (positive electrode active material).

[0231]

[0232] Comparative Example 7

[0233] Ni 0.88 Co 0.05 Mn 0.07 Complex transition metal hydroxides (D) having a composition represented by (OH)2 50 : 9㎛, secondary particle form) was heat treated at 500℃ for 6 hours in an air atmosphere to produce a composite transition metal oxide.

[0234] The above complex transition metal oxide (composition: Ni) 0.88 Co 0.05 Mn 0.07O) and LiOH·H2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.03, and calcined in an oxygen atmosphere at 780°C for 13 hours to produce a lithium composite transition metal oxide (positive electrode active material).

[0235]

[0236] Experimental example

[0237] Experimental Example 1: Measurement of the average crystal size of nickel oxide or complex transition metal oxides.

[0238] For each NiO manufactured in Example 1 and Comparative Examples 3 to 6, after XRD measurement, the XRD data is shown in Fig. 1, and the average crystal size of NiO or composite transition metal oxide is calculated and shown in Table 1 below.

[0239] At this time, XRD (D8-Endeavor, Bruker) collected 2g to 3g of each NiO powder and obtained an X-ray diffraction grating in the 2θ range of 15° to 80° using Cu-Kα rays (wavelength 1.54Å) at an acceleration voltage of 40 kV / 40 mA and a scan speed of 0.1° / sec. By analyzing this, the average crystal size of NiO was quantitatively calculated.

[0240]

[0241] Through Figure 1, it was confirmed that the nickel oxide manufactured in Example 1, i.e., nickel oxide manufactured by heat-treating nickel hydroxide at a temperature of 500°C, had a smaller average crystallite size than the nickel oxide manufactured in Comparative Example 3, i.e., nickel oxide manufactured by heat-treating nickel hydroxide at a temperature of 400°C, and that the nickel oxide manufactured in Comparative Examples 4 to 6, i.e., nickel oxide manufactured by heat-treating at a temperature of 600°C or higher and 750°C or lower, had a larger average crystallite size.

[0242] As a result, it was confirmed that when manufacturing nickel oxide by heat treating nickel hydroxide, the degree of crystallinity can be controlled by the heat treatment temperature.

[0243]

[0244] Experimental Example 2: Measurement of total pore volume of nickel oxide or complex transition metal oxides

[0245] For each NiO prepared in Example 1 and Comparative Examples 3 to 6, the total pore volume and average pore size were calculated and shown in Table 1 below. In addition, for the composite transition metal oxide prepared in Comparative Example 7, the total pore volume was calculated and shown in Table 1 below.

[0246] Specifically, each of the NiO prepared in Example 1 and Comparative Examples 3 to 6 or the composite transition metal oxide prepared in Comparative Example 7 was dried at 130°C for 4 hours in a vacuum atmosphere to remove all moisture, and then the total pore volume and average pore size of the NiO or composite transition metal oxide were measured by the BET method, calculated from the nitrogen gas adsorption amount at a liquid nitrogen temperature (77K) with a relative pressure of 0 to 1 atm using BELSORP-max II of BEL Japan.

[0247] Average crystal size (nm) Total pore volume (cm) 3 / g)Average pore size (nm)Example 139.10.120514.567Comparative example 318.50.14749.020Comparative example 446.90.118331.323Comparative example 592.00.105363.085Comparative example 6106.00.032760.725Comparative example 7-0.12238.6786

[0248] Through Table 1, the nickel oxide manufactured in Example 1, i.e., nickel oxide manufactured by heat-treating nickel hydroxide at a temperature of 500°C, has an average crystallite size of 20.0 nm or more and 45.0 nm or less, and a total pore volume of 0.1200 cm 3 / g or more than 0.1400 cm 3 / g or less, and the average pore size was confirmed to be 10,000 nm or more and 30,000 nm or less.

[0249] Meanwhile, nickel oxides manufactured in Comparative Examples 3, 4, 5 and 6, i.e. nickel oxides manufactured by heat-treating nickel hydroxide at temperatures of 400°C, 600°C, 650°C and 750°C, respectively, have an average crystallite size of less than 20.0 nm or greater than 45.0 nm, and a total pore volume of 0.1200 cm 3 / g or less or 0.1400 cm 3 / g exceeded, and the average pore size was confirmed to be less than 10,000 nm or greater than 30,000 nm. In addition, it was confirmed that the composite transition metal oxide manufactured in Comparative Example 7 had an average crystallite size of greater than 45.0 nm.

[0250] In conclusion, it was confirmed that when manufacturing nickel oxide by heat treating nickel hydroxide, the crystallinity and pores can be controlled depending on the heat treatment temperature.

[0251]

[0252] Experimental Example 3: Measurement of the conversion rate of nickel oxide

[0253] For each NiO manufactured in Example 1 and Comparative Example 3, after thermogravimetric analysis, TGA data is shown in Figure 2 below, and χ and conversion rate are calculated and shown in Table 2 below.

[0254] The above TGA data is data measuring the weight change (%) while heating nickel oxide from 0℃ to 900℃ at a rate of 5-10℃ / min using a thermogravimetric analyzer (Mettler-Toledo, TGA2) in an air atmosphere. In addition, the conversion rate (%) is calculated using the TGA data.

[0255] Specifically, when residual nickel hydroxide exists in nickel oxide, and heat treatment is performed at 900°C using a thermogravimetric analyzer, the following reaction occurs and a weight change (%) appears.

[0256] Ni(OH)2→NiO+H2O

[0257] It is assumed that the measured weight change is determined solely by H2O when all of the residual nickel hydroxide has become nickel oxide, i.e., when no residual nickel hydroxide exists.

[0258] When the weight change in the TGA data of each NiO manufactured in Example 1 and Comparative Example 3 was 100×χ(%), the conversion rate (%) was calculated for each NiO manufactured in Example 1 and Comparative Example 3 according to the following formula.

[0259] [Formula 1]

[0260]

[0261] χ Conversion rate (%) Example 10.01096 Comparative example 30.02589

[0262] Through Table 2, it was confirmed that the nickel oxide manufactured in Example 1, i.e., nickel oxide manufactured by heat-treating nickel hydroxide at a temperature of 500°C, had a conversion rate (%) of 90% or more according to Equation 1.

[0263] Meanwhile, it was confirmed that the nickel oxide manufactured in Comparative Example 3, i.e., nickel oxide manufactured by heat-treating nickel hydroxide at a temperature of 400°C, had a conversion rate (%) according to Equation 1 of approximately 89%.

[0264] In conclusion, it was confirmed that when manufacturing nickel oxide by heat treating nickel hydroxide, the conversion rate (%) can be controlled depending on the heat treatment temperature.

[0265]

[0266] Experimental Example 4: Analysis of Complex Transition Metal Oxides and Cathode Active Materials

[0267] -Composition of complex transition metal oxide and cathode active material

[0268] After taking 0.05 g of the complex transition metal oxide prepared in Example 1, 2 ml of hydrochloric acid was added and heated to dissolve the complex transition metal oxide. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction, completely dissolving the complex transition metal oxide to prepare a solution. Next, the solution was diluted with deionized water to a total volume of 10 ml to prepare an analysis sample. Using an ICP device (Avio series, PerkinElmer), the weight ratio of the constituent elements present in the analysis sample was measured, and the composition of the complex transition metal oxide is shown in Table 3 below.

[0269]

[0270] After taking 0.05 g each of the positive electrode active materials manufactured in Examples 1 and 2, 2 ml of hydrochloric acid was added and heated to dissolve the positive electrode active material. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction, completely dissolving the positive electrode active material to prepare a solution. Next, the solution was diluted with deionized water to a total volume of 10 ml to prepare an analysis sample. Using an ICP device (Avio series, PerkinElmer), the weight ratio of the constituent elements present in the analysis sample was measured, and the composition of the positive electrode active material is shown in Table 3 below.

[0271] Composition complex transition metal oxide cathode active material Example 1 Ni 0.95 Co 0.02 Mn 0.03 OLi 1.073 Ni 0.95 Co 0.02 Mn 0.03 O2 Example 2Ni 0.88 Co 0.05 Mn 0.07 OLi 1.065 Ni 0.88 Co 0.05 Mn 0.07 O2

[0272] Through Table 3, it was confirmed that the composite transition metal oxide and positive electrode active material manufactured in Examples 1 and 2 had a nickel content of 80 mol% or more among the total transition metals.

[0273]

[0274] - Form of complex transition metal oxide and cathode active material

[0275] For the composite transition metal oxide manufactured in Example 1, an SEM image taken at 5K magnification was obtained using a scanning electron microscope (SEM), and this is shown in Fig. 3. For the positive electrode active material manufactured in Example 1, SEM images taken at 5K magnification and 20K magnification were obtained, and this is shown in Figs. 5 and 6. In addition, for the positive electrode active material manufactured in Example 2, an SEM image taken at 5K magnification was obtained, and this is shown in Fig. 7.

[0276] And, for the composite transition metal oxide and positive electrode active material manufactured in Comparative Example 7, cross-sectional SEM images were obtained, and these are shown in FIGS. 4 and 8, respectively. Specifically, in order to obtain cross-sectional SEM images, 96 wt% of the composite transition metal oxide or positive electrode active material, 2 wt% of the conductive agent, and 2 wt% of PVDF as a binder were mixed in an N-methylpyrrolidone (NMP) solvent to prepare a positive electrode slurry, and the prepared positive electrode slurry was applied to one surface of an aluminum current collector, and then dried at 130°C to manufacture an electrode for cross-sectional measurement, and the manufactured electrode was cut using an ion milling device to prepare a specimen for SEM measurement.

[0277]

[0278] Figure 3 is a SEM image (5K magnification) of the composite transition metal oxide manufactured in Example 1.

[0279] Figure 4 is a cross-sectional SEM image of the composite transition metal oxide manufactured in Comparative Example 7.

[0280] Figure 5 is a SEM image (5K magnification) of the positive electrode active material manufactured in Example 1.

[0281] Figure 6 is a SEM image (20K magnification) of the positive electrode active material manufactured in Example 1.

[0282] Figure 7 is a SEM image (5K magnification) of the positive electrode active material manufactured in Example 2.

[0283] Figure 8 is a cross-sectional SEM image of the positive electrode active material manufactured in Comparative Example 7.

[0284]

[0285] Through FIG. 3, it was confirmed that the composite transition metal oxide manufactured in Example 1 according to the present invention was in the form of spherical secondary particles, and through FIG. 4, it was confirmed that the composite transition metal oxide manufactured in Comparative Example 7 was in the form of spherical secondary particles.

[0286] Through FIGS. 5 to 7, it was confirmed that the positive electrode active material manufactured in Examples 1 and 2 according to the present invention was in the form of spherical secondary particles, and through FIG. 8, it was confirmed that the positive electrode active material manufactured in Comparative Example 7 was in the form of spherical secondary particles.

[0287]

[0288] -Particle size of composite transition metal oxide and cathode active material

[0289] Using PSA (LA-960V2, Horiba), the nickel hydroxide used in Example 1, NiO prepared in Example 1, composite transition metal oxide and positive electrode active material D min , D 10 , average particle diameter (D 50 ), D 90 , D max The values ​​were measured and shown in Table 4 below, and the span value according to Equation 2 below was calculated and shown in Table 4 below, and the ratio of particles with a particle size of less than 3㎛ and the ratio of particles with a particle size of more than 20㎛ were measured and shown in Table 4 below.

[0290] [Formula 2]

[0291]

[0292] (A) is nickel hydroxide used in Example 1, (B) is NiO manufactured in Example 1, (C) is a composite transition metal oxide manufactured in Example 1, and (D) is a positive electrode active material manufactured in Example 1.

[0293] Particle size (㎛) ratio (%)D min D 10 D 50 D 90 D max span<3㎛>20㎛(A)0.36.214.422.039.21.097.38116.659(B)6.712.119.033.7101.51.1 4044.936(C)6.712.119.639.3344.21.39048.192(D)5.19.314.420.634.30.8013.030

[0294] Through Table 4, nickel hydroxide has an average particle size (D 50 ) was confirmed to be 5㎛ or more and 20㎛ or less, and the composite transition metal oxide had an average particle diameter (D 50 ) was confirmed to be 7㎛ or more and 25㎛ or less. In addition, the positive electrode active material had an average particle diameter (D 50 ) was 10㎛ or more and 25㎛ or less, and the span value was 0.7 or more and 2 or less.

[0295]

[0296] Experimental Example 5: Battery Characteristics Evaluation

[0297] - Coin-type half-cell manufacturing

[0298] A positive electrode slurry was prepared by mixing 95 wt% of the positive electrode active material manufactured in the above examples and comparative examples, 2.2 wt% of FX35 as a conductive agent, and 2.8 wt% of polyvinylidene fluoride (PVDF, KF9709) as a binder in an N-methylpyrrolidone (NMP) solvent. The prepared positive electrode slurry was applied to one surface of an aluminum current collector, dried at 130°C, and then rolled to prepare a positive electrode.

[0299] An electrode assembly was manufactured using a lithium metal electrode as the negative electrode and a porous polyethylene separator interposed between the positive and negative electrodes. This was placed inside a battery case, and a coin-type half-cell was manufactured by injecting an electrolyte solution containing 1 M LiPF6 dissolved in an organic solvent containing ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) in a volume ratio of 3:4:3.

[0300]

[0301] Using the coin-type half-cell manufactured as described above, the activation process (formation) was performed by charging (0.1C) in the CC-CV manner to 4.25 V at 25°C and then discharging (0.1C) in the CC manner to 2.0 V.

[0302] Immediately after performing the activation process, the capacity characteristics, rate characteristics, and life characteristics of the battery were evaluated using the following method.

[0303]

[0304] -Evaluation of battery capacity characteristics

[0305] Charge current / discharge current (0.1C / 0.1C)

[0306] Immediately after the activation process, the battery was charged (0.1C, cut-off current: 0.05C) to 4.25 V at 25°C using the CC-CV method, and then discharged (0.1C) to 2.0 V using the CC method, and the charge / discharge capacity (mAh / g) at this time was measured. The measured charge / discharge capacity (mAh / g) and the percentage of discharge capacity to charge capacity (efficiency (%)) are shown in Table 5 below. The charge / discharge capacity measured according to voltage is shown in Figures 9 and 10 below.

[0307] Figure 9 is a charge / discharge curve of a battery including each of the positive electrode active materials manufactured in Example 1 and Comparative Example 1.

[0308] Figure 10 is a charge / discharge curve of a battery including each of the positive electrode active materials manufactured in Example 2 and Comparative Example 2.

[0309] Charge current / discharge current (0.33C / 0.33C)

[0310] After charging (0.33C, cut-off current: 0.05C) to 4.25 V at 25 ℃ using the CC-CV method, discharging (0.33C) to 2.0 V using the CC method, the charge / discharge capacity at this time was measured in the same manner as the charge current / discharge current (0.1C / 0.1C), and the measured charge / discharge capacity (mAh / g) and the percentage of discharge capacity to charge capacity (efficiency (%)) are shown in Table 5 below.

[0311] 0.1C / 0.1C0.33C / 0.33CCharge capacity (mAh / g)Discharge capacity (mAh / g)Efficiency (%)Charge capacity (mAh / g)Discharge capacity (mAh / g)Efficiency (%)Example 1243.9222.191.1226.5211.993.6Example 2228.3205.389.9208.7196.394.1Comparative example 1242.0223.192.2227.3212.593.5Comparative example 2228.8191.583.7195.4183.794.0Comparative example 4244.0216.188.6220.3207.894.3Comparative example 5235.0203.186.4205.5191.393.1

[0312] Through Table 5, it was confirmed that the secondary battery including the cathode active material including the lithium composite transition metal oxide prepared by mixing and firing the composite transition metal hydroxide having a nickel content of 88 mol% among the total transition metals and the lithium-containing raw material, compared to Comparative Example 2, that is, the secondary battery including the cathode active material including the lithium composite transition metal oxide prepared by mixing and firing the composite transition metal hydroxide having a nickel content of 88 mol% among the total transition metals and the lithium-containing raw material, has excellent discharge capacity and efficiency at 0.1C / 0.1C and 0.33C / 0.33C and charge capacity at 0.33C / 0.33C.

[0313] Comparative Example 1, that is, a secondary battery including a cathode active material including a lithium composite transition metal oxide manufactured by mixing and firing a composite transition metal hydroxide having a nickel content of 95 mol% among all transition metals and a lithium-containing raw material, compared to Example 1, that is, a secondary battery including a cathode active material including a lithium composite transition metal oxide manufactured by mixing and firing a composite transition metal hydroxide having a nickel content of 95 mol% among all transition metals and a lithium-containing raw material, was confirmed to have equivalent levels of discharge capacity, efficiency, etc. at 0.1C / 0.1C and 0.33C / 0.33C.

[0314] In addition, it was confirmed that the secondary battery including the cathode active material including the lithium composite transition metal oxide prepared by dry-mixing nickel oxide, cobalt-containing raw material, and manganese-containing raw material and heat-treating at a temperature of 600°C or higher, compared to Comparative Examples 4 and 5, that is, the secondary battery including the cathode active material including the lithium composite transition metal oxide prepared by dry-mixing nickel oxide, cobalt-containing raw material, and manganese-containing raw material and heat-treating at a temperature of more than 400°C and less than 600°C, and the lithium composite transition metal oxide prepared by mixing and firing the lithium-containing raw material had significantly superior discharge capacities at 0.1C / 0.1C and 0.33C / 0.33C and efficiencies at 0.1C / 0.1C, and the efficiencies at 0.33C / 0.33C were at an equivalent level.

[0315] Meanwhile, for Comparative Example 3, the residual nickel hydroxide content was excessive and the conversion rate was small, so a battery characteristic evaluation was not performed, and for Comparative Example 6, the average crystal size was too large, so it was expected that the residual nickel hydroxide content would be excessive and the conversion rate would be small, so a battery characteristic evaluation was not performed.

[0316]

[0317] -Evaluation of the rate characteristics of the battery

[0318] Charge current / discharge current (0.5C / 0.1C)

[0319] After charging (0.5C, cut-off current: 0.05C) to 4.25 V at 25 ℃ using the CC-CV method, the battery was discharged (0.1C) to 2.0 V using the CC method, and the discharge capacity (mAh / g) at this time was measured. The measured discharge capacity (mAh / g) is shown in Table 6 below.

[0320] Charge current / discharge current (0.5C / 1C)

[0321] After charging (0.5C, cut-off current: 0.05C) to 4.25 V in the CC-CV manner at 25 ℃, discharging (1C) to 2.0 V in the CC manner, the discharge capacity at this time was measured in the same manner as the charge current / discharge current (0.5C / 0.1C), and the measured discharge capacity (mAh / g) is shown in Table 6 below.

[0322] Charge current / discharge current (0.5C / 2C)

[0323] After charging (0.5C, cut-off current: 0.05C) to 4.25 V in the CC-CV manner at 25 ℃, discharging (2C) to 2.0 V in the CC manner, the discharge capacity at this time was measured in the same manner as the charge current / discharge current (0.5C / 2C), and the measured discharge capacity (mAh / g) is shown in Table 6 below.

[0324]

[0325] The percentage of the discharge capacity measured when the charge current / discharge current is 0.5C / 0.1C to the discharge capacity measured when the charge current / discharge current is 0.5C / 0.1C (rate characteristic C 0.5C / 0.1C (%)), the percentage of the discharge capacity measured when the charge current / discharge current is 0.5C / 1C to the discharge capacity measured when the charge current / discharge current is 0.5C / 0.1C (rate characteristic C 0.5C / 1C (%)) and percentage of discharge capacity measured when charge current / discharge current is 0.5C / 2C to discharge capacity measured when charge current / discharge current is 0.5C / 0.1C (rate characteristic C 0.5C / 2C (%)) are shown in Table 6 below.

[0326] Discharge capacity (mAh / g) rate characteristics (%) 0.5C / 0.1C 0.5C / 1C 0.5C / 2CC 0.5C / 0.1C C 0.5C / 1C C 0.5C / 2CExample 1219.6201.3194.510091.788.6 Example 2205.5188.1181.110091.588.1 Comparative Example 1222.2202.4196.410091.188.4 Comparative Example 2192.9175.8168.210091.187.2

[0327] Through Table 6, Comparative Example 1, that is, a secondary battery including a cathode active material including a lithium composite transition metal oxide manufactured by mixing and firing a composite transition metal hydroxide having a nickel content of 95 mol% among the total transition metals and a lithium-containing raw material, compared to Example 1, that is, a secondary battery including a cathode active material including a lithium composite transition metal oxide manufactured by mixing and firing a composite transition metal hydroxide having a nickel content of 95 mol% among the total transition metals and a lithium-containing raw material, has the same discharge capacity at 0.5C / 0.1C, 0.5C / 1C and 0.5C / 2C, and C 0.5C / 1C and C 0.5C / 2C It was confirmed that it was excellent.

[0328] In addition, in Comparative Example 2, that is, a secondary battery including a cathode active material including a lithium composite transition metal oxide manufactured by mixing and firing a composite transition metal hydroxide having a nickel content of 88 mol% among the total transition metals and a lithium-containing raw material, compared to Example 2, that is, a secondary battery including a cathode active material including a lithium composite transition metal oxide manufactured by mixing and firing a composite transition metal hydroxide having a nickel content of 88 mol% among the total transition metals and a lithium-containing raw material, has discharge capacities and C at 0.5C / 0.1C, 0.5C / 1C, and 0.5C / 2C. 0.5C / 0.1C, C 0.5C / 1C, C 0.5C / 2C It was confirmed that it was excellent.

[0329]

[0330] - Evaluation of battery life characteristics

[0331] Immediately after performing the activation process, the battery was charged to 4.25 V at 45°C using the CC-CV method (0.5 C, cut-off current: 0.05 C), then discharged to 3.0 V using the CC method (1.0 C) 50 times, which was considered one cycle, and the discharge capacity at each cycle was measured.

[0332] For Examples 1 and 2 and Comparative Examples 1, 2 and 7, the percentage of the discharge capacity of the 50th cycle to the discharge capacity of the first cycle is represented as the capacity retention rate (%) and is shown in Table 7 below.

[0333] Capacity retention rate (%) Example 184.5 Example 295.2 Comparative example 183.7 Comparative example 293.8 Comparative example 791.8

[0334] Through Table 7, it can be confirmed that the secondary batteries including the positive electrode active materials manufactured in Examples 1 and 2 have superior capacity retention compared to the batteries including the positive electrode active materials of the comparative examples having the same composition.

[0335]

[0336] In conclusion, it was confirmed that the secondary battery including the positive electrode active material according to the present invention has excellent rate characteristics while maintaining the discharge capacity at the same level as the secondary battery including Comparative Examples 1 and 2 using a composite transition metal hydroxide as a positive electrode active material precursor, and among them, the rate characteristics C 0.5C / 1C (%) was confirmed to be excellent. In addition, when manufacturing a composite transition metal oxide, it was confirmed that the discharge capacity and efficiency at 0.1C / 0.1C and 0.33C / 0.33C were excellent compared to the secondary batteries including Comparative Examples 3 to 5 that were heat-treated at 400°C or less or 600°C or more. In addition, it was confirmed that the capacity retention rate was excellent compared to the secondary battery including Comparative Example 7 that was manufactured by heat-treating a composite transition metal hydroxide using a composite transition metal oxide as a cathode active material.

Claims

1. (A 0 ) A step of manufacturing nickel oxide by heat-treating nickel hydroxide at a temperature exceeding 400℃ and less than 600℃; (A) a step of dry mixing the nickel oxide, cobalt-containing raw material and manganese-containing raw material and heat-treating them at a temperature of more than 400°C and less than 600°C to produce a composite transition metal oxide; (B) a step of preparing a mixture by mixing the above complex transition metal oxide and a lithium-containing raw material; and (C) A method for producing a cathode active material, comprising the step of producing a lithium composite transition metal oxide by calcining the mixture.

2. In claim 1, The heat treatment of step (A) above and the (A) above 0 ) A method for manufacturing a cathode active material, wherein the heat treatment of the step is performed under the same temperature.

3. In claim 1, A method for manufacturing a cathode active material, wherein the above nickel oxide has an average crystallite size of 20.0 nm or more and 45.0 nm or less.

4. In claim 1, The above nickel oxide has a total pore volume of 0.1200 cm 3 / g or more than 0.1400 cm 3 A method for manufacturing a positive electrode active material having a mass of / g or less.

5. In claim 1, A method for manufacturing a cathode active material, wherein the above nickel oxide has an average pore size of 10,000 nm or more and 30,000 nm or less.

6. In claim 1, The above nickel oxide is a method for manufacturing a cathode active material having a conversion rate of 90% or more according to the following formula 1: [Formula 1] The above χ is the value that appears as 100×χ(%) in the TGA data when the weight change (%) is measured while increasing the temperature of nickel oxide from 0℃ to 900℃ at a rate of 5 to 10℃ / min in an air atmosphere using a thermogravimetric analyzer.

7. In claim 1, A method for producing a cathode active material, wherein the above composite transition metal oxide has a nickel content of 80 mol% or more among the total transition metals.

8. In claim 1, A method for producing a cathode active material, wherein the above composite transition metal oxide is in the form of secondary particles.

9. In claim 1, The above step (B) is a method for producing a cathode active material, wherein a mixture is produced by mixing a composite transition metal oxide and a lithium-containing raw material so that the molar ratio of lithium (Li) to transition metal (M) (Li / M) is 0.95 or more and 1.05 or less.

10. In claim 1, In the above step (B), a mixture is prepared by further mixing a raw material containing a doping element, A method for producing a cathode active material, wherein the above doping element is at least one selected from the group consisting of Al, Y, Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and La.

11. In claim 1, A method for producing a cathode active material, wherein the above-mentioned calcination is performed in an oxygen atmosphere.

12. In claim 1, A method for manufacturing a cathode active material, wherein the above-mentioned calcination is performed at a temperature of 700°C or higher and 800°C or lower.

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