Positive electrode active material, method for preparing same, and rechargeable lithium battery

Abstract

The present application relates to a positive electrode active material, a method of preparing the positive electrode active material, and a rechargeable lithium battery including the positive electrode active material, the method comprising adding lithium hydroxide, nickel sulfate, cobalt sulfate, and ammonium carbonate to an aqueous solvent and mixing them to prepare a raw material mixture, wet-pulverizing the raw material mixture, the pulverized raw material mixture is spray-dried to obtain a positive electrode active material precursor mixture, and the positive electrode active material precursor mixture is heat-treated to obtain a positive electrode active material that is in the form of a single particle and includes a lithium nickel cobalt-based composite oxide.

Description

Technical Field

[0001] Embodiments of the present disclosure described herein relate to a positive electrode active material, a method for preparing the positive electrode active material, and a rechargeable lithium battery including the positive electrode active material. Background Art

[0002] Portable information devices (such as cellular phones, laptop computers, smart phones, etc.) and / or electric vehicles have used rechargeable lithium batteries with relatively high energy density and easy portability as a driving power source. Recently, exploration or implementation has been made to use rechargeable lithium batteries with high energy density as a driving power source for hybrid vehicles or electric vehicles, or as a power storage source for an energy storage system or a power wall.

[0003] Various positive electrode active materials have been used in rechargeable lithium batteries. For example, lithium nickel-based oxides, lithium nickel manganese cobalt-based composite oxides, lithium nickel cobalt aluminum-based composite oxides, and lithium cobalt-based oxides have been used as positive electrode active materials. Nickel-based positive electrode active materials can be in the form of secondary particles (e.g., each) made by aggregating a plurality of primary particles, but methods of preparing them in the form of single particles by methods such as pulverization or high-temperature treatment can also be used. Nickel-based positive electrode active materials in the form of single particles can improve cycle life characteristics, and if (e.g., when) mixed with secondary particles, they can increase the energy density. That is, if (e.g., when) a nickel-based positive electrode active material is included in the form of single particles, the cycle life characteristics of the rechargeable lithium battery can be improved. In addition, the energy density of the rechargeable lithium battery can be increased by mixing single particles with secondary particles. Summary of the Invention

[0004] Aspects according to one or more embodiments relate to a method for preparing nickel-based single particle positive electrode active materials as a one-step (e.g., one action or one task) process, which reduces the total production and processing costs and improves processability by omitting or not including (e.g., excluding any) the process of synthesizing a positive electrode active material precursor, and provides a method for preparing a positive electrode active material capable of achieving a substantially uniform particle size distribution, a high initial discharge capacity, a high initial charge and discharge efficiency, and long cycle life characteristics. That is, specific embodiments propose a streamlined method for producing nickel-based single particle positive electrode active materials. The method is a one-step process and does not require the synthesis of a positive electrode active material precursor. The purpose of this is to reduce production and processing costs while improving processability. The proposed method facilitates the production of a positive electrode active material characterized by a significantly uniform particle size distribution, a high initial discharge capacity, a high initial charge and discharge efficiency, and an extended cycle life characteristic.

[0005] In one or more embodiments, a method for preparing a positive electrode active material includes: adding lithium hydroxide, nickel sulfate, cobalt sulfate, and ammonium carbonate (NH4HCO3 or (NH4)2CO3) to an aqueous solvent and mixing them to prepare a raw material mixture, subjecting the raw material mixture to wet grinding, spray-drying the ground raw material mixture to obtain a positive electrode active material precursor mixture, and heat-treating the positive electrode active material precursor mixture to obtain a positive electrode active material in the form of single particles and including a lithium nickel cobalt composite oxide.

[0006] In one or more embodiments, the positive electrode active material includes a lithium nickel cobalt composite oxide and is in the form of single particles, wherein the average particle size (D 50 ) of the single particles is from about 0.5 μm to about 8 μm and the span ((D 90 -D 10 ) / D 50 ) value is from about 0.7 to about 1.30.

[0007] In one or more embodiments, a rechargeable lithium battery includes: a positive electrode including a positive electrode active material, a negative electrode, and an electrolyte.

[0008] In one or more embodiments, the method for preparing the positive electrode active material is a method for preparing a nickel-based single-particle positive electrode active material and is a one-step (e.g., one action or one task) synthesis method, wherein the precursor synthesis process is omitted, thereby significantly reducing the total production and processing costs and improving the processability. The positive electrode active material prepared thereby may have a substantially very uniform particle size distribution, and the rechargeable lithium battery using this material may achieve a high initial discharge capacity and initial charge and discharge efficiency, and exhibit excellent or appropriate cycle life characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figures 1 to 4 are schematic diagrams each showing a rechargeable lithium battery according to one or more embodiments.

[0010] Figure 5 and Figure 6 is a SEM image of the positive electrode active material prepared in Example 1.

[0011] REFERENCE SIGNS

[0012] 100: Rechargeable lithium battery 10: Positive electrode

[0013] 11: Positive electrode lead tab 12: Positive electrode terminal

[0014] 20: Negative electrode 21: Negative electrode lead tab

[0015] 22: Negative electrode terminal 30: Separator

[0016] 40: Electrode assembly 50: Housing

[0017] 60: Sealing member 70: Electrode tab

[0018] 71: Positive electrode tab 72: Negative electrode tab Detailed implementation manners

[0019] Hereinafter, one or more embodiments will be described in more detail so that those of ordinary skill in the art can more easily implement them. However, the present disclosure can be embodied in many different forms and is not to be construed as limited to the exemplary embodiments set forth herein.

[0020] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of...", "one of...", and "selected from...", when used before / after a list of elements, modify the entire list of elements and do not modify a single element of the list. For example, "at least one of a, b, and c", "any one selected from a, b, and c", etc. can indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0021] The terms used herein are only for describing the embodiments and are not intended to limit the scope of the present disclosure. Unless the context clearly indicates otherwise, singular expressions include plural expressions.

[0022] As used herein, "a combination thereof" refers to a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of components.

[0023] In this document, it should be understood that terms such as "comprising", "including", or "having" are intended to indicate the presence of specific aspects, quantities, steps (e.g., actions or tasks), elements, and / or combinations thereof (e.g., any suitable combination), but they do not exclude the possibility of the presence or addition of one or more other features, quantities, steps (e.g., actions or tasks), elements, and / or combinations thereof (e.g., any suitable combination).

[0024] In the accompanying drawings, for the sake of clarity, the dimensions (e.g., thickness) of layers, films, panels, regions, etc. may be enlarged, and throughout the specification, the same reference numerals denote the same elements, and their repeated description may not be provided in the specification. It will be understood that if (e.g., when) an element (such as a layer, film, region, or substrate) is referred to as being “on” another element (such as a layer, film, region, or substrate), it may be directly on the other element (such as a layer, film, region, or substrate), or intervening elements may also be present. In contrast, if (e.g., when) an element (such as a layer, film, region, or substrate) is referred to as being “directly on” another element (such as a layer, film, region, or substrate), there are no intervening elements.

[0025] In addition, “layer” herein includes not only a shape formed on the entire surface when viewed in plan view (e.g., when), but also a shape formed on a partial surface.

[0026] In the present disclosure, when the particles are spherical, “diameter” indicates the particle size or average particle size, and when the particles are non-spherical, “diameter” indicates the major axis length or average major axis length. The average particle size can be measured by methods well known to those skilled in the art (e.g., by a particle size analyzer or by transmission electron microscope images or scanning electron microscope images). In one or more embodiments, the average particle size value can be obtained by performing measurements using a dynamic light scattering method, performing data analysis, counting the number of particles in each particle size range, and thereby performing calculations. Unless otherwise defined, the average particle size (D 50 ) may refer to the diameter of the particles with a cumulative volume of 50% by volume in the particle size distribution. As used herein, if no other definition is provided, the average particle size (D 50 ) refers to the diameter of the particles with a cumulative volume of 50% by volume in the particle size distribution obtained by randomly measuring the sizes (diameter or major axis length) of about 20 particles in a scanning electron microscope image.

[0027] In this document, “or” is not interpreted in an exclusive sense. For example, “A or B” is interpreted as including A, B, A + B, etc.

[0028] “Metal” is interpreted to include the concepts of ordinary metals, transition metals, and metalloids (semi-metals).

[0029] Method for preparing a positive electrode active material

[0030] In one or more embodiments, a method of preparing a positive electrode active material includes: adding lithium hydroxide, nickel sulfate, cobalt sulfate, and ammonium carbonate to an aqueous solvent and mixing them to prepare a raw material mixture, subjecting the raw material mixture to wet grinding, spray-drying the ground raw material mixture to obtain a positive electrode active material precursor mixture, and heat-treating the positive electrode active material precursor mixture to obtain the positive electrode active material in the form of single particles, the positive electrode active material including a lithium nickel cobalt composite oxide.

[0031] The preparation method may include: a method of synthesizing single-particle positive electrode active material by mixing lithium hydroxide, a metal raw material of sulfate, and ammonium carbonate, and then subjecting the mixture to wet grinding, spray-drying, and heat treatment (e.g., firing). This method can reduce production and processing costs by omitting (e.g., not including or excluding) (any) process of synthesizing a nickel hydroxide precursor in a coprecipitation method, etc. This method can improve processability as a one-step (e.g., one action or one task) process. In addition, a positive electrode active material is provided, which exhibits a substantially more uniform particle size distribution and achieves more excellent or appropriate initial discharge capacity, initial charge and discharge efficiency, and cycle life characteristics compared to positive electrode active materials prepared by comparable methods.

[0032] The raw material mixture includes a metal raw material of sulfate (such as nickel sulfate and cobalt sulfate) and lithium hydroxide as a lithium raw material. If (e.g., when) ammonium carbonate is added thereto during the mixing process of the raw materials, nickel sulfate becomes nickel carbonate, cobalt sulfate becomes cobalt carbonate, and lithium hydroxide becomes lithium carbonate. For example, they are converted into a metal raw material of carbonate. If (e.g., when) a metal raw material of carbonate is used, since the carbonate decomposes in the subsequent heat treatment in a temperature range of about 700 °C to about 900 °C and is released as CO2, the metal raw material of carbonate can react better during this carbonate decomposition process to effectively prepare single-particle nickel-based positive electrode active material. For example, if a hydroxide, oxide, nitroxide, oxyhydroxide, organic acid, or chloride form other than sulfate is used as the metal raw material, or if lithium hydroxide is not used, or if ammonium carbonate is not added, the metal raw material of carbonate will not be formed as an intermediate material. Therefore, by the preparation method according to one or more embodiments, it may not be possible to effectively synthesize the desired or appropriate single-particle (e.g., single integral particle) form of nickel-based positive electrode active material.

[0033] According to an example, a method for preparing a positive electrode active material may include: adding lithium hydroxide, nickel sulfate, and cobalt sulfate to an aqueous solvent, then adding ammonium carbonate thereto, and mixing them to obtain a metal carbonate raw material and obtain a raw material mixture, thereby forming a precipitate of a hydroxide type or species. That is, the process of synthesizing the positive electrode active material involves generating a precipitate of a hydroxide (type or species). This is accomplished by introducing lithium hydroxide, nickel sulfate, and cobalt sulfate into an aqueous solvent and then adding ammonium carbonate. Then these substances are blended to form a metal carbonate raw material, thereby preparing a mixed raw material (i.e., the raw material mixture).

[0034] Other metal raw materials may be further added to the raw material mixture. For example, a manganese raw material and / or an aluminum raw material may be further added to the raw material mixture. According to one or more embodiments, a lithium nickel cobalt manganese composite oxide, a lithium nickel cobalt aluminum composite oxide, or a lithium nickel cobalt manganese aluminum composite oxide may be synthesized. The manganese raw material may be manganese sulfate, and the aluminum raw material may be aluminum hydroxide, aluminum oxide, and / or a combination thereof (e.g., any suitable combination). For example, in the preparation of the raw material mixture, manganese sulfate, aluminum hydroxide, aluminum oxide, and / or a combination thereof (e.g., any suitable combination) are further mixed.

[0035] The metal raw materials may be mixed in a suitable or appropriate molar ratio in the raw material mixture. For example, the metal raw materials may be mixed such that based on 100 mol% of the total metal other than lithium in the prepared positive electrode active material, the nickel content (e.g., amount) may be about 30 mol% to about 99 mol%, and the cobalt content (e.g., amount) may be about 1 mol% to about 70 mol%. However, for another example, based on 100 mol% of the total metal other than lithium in the prepared positive electrode active material, the nickel content (e.g., amount) may be about 30 mol% to about 98 mol%, the cobalt content (e.g., amount) may be about 1 mol% to about 40 mol%, and the manganese and / or aluminum content (e.g., amount) may be about 1 mol% to about 40 mol%.

[0036] Lithium hydroxide may be mixed such that the molar ratio of lithium to the total metal of the metal raw materials in the raw material mixture is about 0.9 to about 1.8, for example, about 0.9 to about 1.5, about 0.9 to about 1.2, about 0.9 to about 0.99, or about 1.01 to about 1.1. If (e.g., when) the molar ratio of lithium satisfies this range, a positive electrode active material having a high initial discharge capacity and excellent or appropriate structural stability may be prepared.

[0037] In the preparation step (e.g., action or task) of the raw material mixture, a dopant raw material may be further mixed. The dopant raw material may be other elements except (e.g., excluding) any one selected from Ni, Co, Mn, and Al, and may include, for example, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zr, and / or combinations thereof (e.g., any suitable combination). That is, during the preparation of the raw material mixture, additional dopant raw materials may be incorporated. The dopant consists of elements other than Ni, Co, Mn, and Al. For example, the dopant may include B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zr, and / or combinations thereof (e.g., any suitable combination). The dopant raw material may be in the form of one or more suitable compounds such as carbonates, hydroxides, oxides, oxynitrides, and / or oxysulfides.

[0038] In the preparation method according to one or more embodiments, the raw material mixture may not be dry-mixed but wet-mixed, and then, wet grinding and spray drying are performed. The wet grinding may be carried out by using wet grinding equipment, for example, by using a ball milling method (using zirconia beads). The wet grinding may be carried out, for example, at about 2000 rpm to about 5000 rpm, for example, at about 3000 rpm to about 4000 rpm. Additionally, the wet grinding may be carried out for about 5 minutes to about 120 minutes or about 10 minutes to about 60 minutes. The ground composition (e.g., the ground raw material mixture) may have particles with an average particle size (D 50 ) less than or equal to about 1 μm, less than or equal to about 0.5 μm, or less than or equal to about 0.1 μm. The diameter of the zirconia beads used in the ball milling may be, for example, 0.1 mm to 1 mm, 0.3 mm to 0.8 mm, or 0.5 mm to 0.7 mm, but is not limited thereto. If (e.g., when) the wet grinding is carried out under such conditions, a nickel-based positive electrode active material in the form of single particles with a substantially uniform particle size distribution can be effectively prepared.

[0039] The spray drying may be carried out by using a conventional spray drying device. For example, the spray drying may be carried out at about 5 mm / min to about 30 mm / min or about 10 mm / min to about 15 mm / min. Additionally, the spray drying may be carried out, for example, at about 150 °C to about 400 °C or about 200 °C to about 300 °C. For example, in the spray drying, the hot air temperature may be set at about 200 °C to about 300 °C, and the hot air discharge temperature may be set at about 100 °C to about 150 °C. If the spray drying is carried out under such conditions, a nickel-based positive electrode active material in the form of single particles with a substantially uniform particle size distribution can be effectively obtained.

[0040] For example, in spray drying, some Li2CO3 can be recovered. For example, during spray drying, Li2CO3 dissolved in water vapor can be discharged, but some Li2CO3 can be recovered by precipitation of the solution.

[0041] The obtained material from spray drying can be a mixture of lithium carbonate and other metal carbonates (such as nickel carbonate and cobalt carbonate), which can be represented as a precursor mixture of the positive electrode active material. The obtained precursor mixture of the positive electrode active material can be in the form of, for example, an aggregate of small particles with an average particle size less than or equal to about 1 μm.

[0042] The spray-dried precursor mixture of the positive electrode active material can be heat-treated (for example, subjected to heat treatment), for example, in an oxygen atmosphere, at a temperature range of about 800 °C to about 1000 °C, for example, about 800 °C to about 980 °C or about 820 °C to about 950 °C. Additionally, the heat treatment can be carried out for about 4 hours to about 24 hours, for example, about 5 hours to about 10 hours.

[0043] The obtained lithium nickel cobalt composite oxide can be represented by Chemical Formula 1.

[0044] Chemical Formula 1

[0045] Li a1 Ni x1 Co y1 M 1 z1 O 2-b1 X b1

[0046] In Chemical Formula 1, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 < 1, 0 < y1 ≤ 0.7, 0 ≤ z1 ≤ 0.4, 0.9 ≤ x1 + y1 + z1 ≤ 1.1, and 0 ≤ b1 ≤ 0.1, M 1 is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from F, P, and S.

[0047] In Chemical Formula 1, for example, 0.9 ≤ a1 ≤ 1.5, or 0.9 ≤ a1 ≤ 1.2, or 1.01 ≤ a1 ≤ 1.1, 0.3 ≤ x1 ≤ 0.99, 0.01 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.4, or 0.3 ≤ x1 ≤ 0.9, 0.1 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.4, or 0.4 ≤ x1 ≤ 0.9, 0.1 ≤ y1 ≤ 0.6, 0 ≤ z1 ≤ 0.4, or 0.5 ≤ x1 ≤ 0.8, 0.2 ≤ y1 ≤ 0.5, 0 ≤ z1 ≤ 0.3, or 0.5 ≤ x1 ≤ 0.7, 0.3 ≤ y1 ≤ 0.5, 0 ≤ z1 ≤ 0.2.

[0048] As an example, the lithium nickel cobalt composite oxide can be represented by Chemical Formula 2. Chemical Formula 2 can be a lithium nickel cobalt manganese composite oxide, a lithium nickel cobalt aluminum composite oxide, or a lithium nickel cobalt manganese aluminum composite oxide.

[0049] Chemical Formula 2

[0050] Li a2 Ni x2 Co y2 M 2 z2 M 3 w2 O 2-b2 X b2

[0051] In Chemical Formula 2, 0.9 ≤ a2 ≤ 1.8, 0.3 ≤ x2 ≤ 0.98, 0.01 ≤ y2 ≤ 0.4, 0.01 ≤ z2 ≤ 0.4, 0 ≤ w2 ≤ 0.1, 0.9 ≤ x2 + y2 + z2 + w2 ≤ 1.1, and 0 ≤ b2 ≤ 0.1, M 2 is Al, Mn, and / or a combination thereof (e.g., any suitable combination), M 3 is one or more elements selected from B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from F, P, and S.

[0052] In Chemical Formula 2, 0.9 ≤ a2 ≤ 1.5 or 0.9 ≤ a2 ≤ 1.2 or 1.01 ≤ a2 ≤ 1.1, 0.3 ≤ x2 ≤ 0.9, 0.01 ≤ y2 ≤ 0.4, 0.01 ≤ z2 ≤ 0.4, 0 ≤ w2 ≤ 0.1, or 0.5 ≤ x2 ≤ 0.8, 0.1 ≤ y2 ≤ 0.4, 0.1 ≤ z2 ≤ 0.4, 0 ≤ w2 ≤ 0.1, or 0.5 ≤ x2 ≤ 0.7, 0.1 ≤ y2 ≤ 0.4, 0.1 ≤ z2 ≤ 0.4, 0 ≤ w2 ≤ 0.1.

[0053] The average particle size (D of the prepared single particles 50) can be from about 0.5 μm to about 8 μm, such as from about 1 μm to about 6 μm or from about 2 μm to about 5 μm, for example, from about 2.5 μm to about 5.0 μm, from about 2.5 μm to about 3.8 μm or from about 2.8 μm to about 3.6 μm.

[0054] According to the preparation method of one or more embodiments, the single particles prepared can have a substantially uniform particle size distribution. For example, particles that are much larger or much smaller than the average particle size (D 50 ) can be present in a low ratio. For example, the single particles prepared can have the following span: that is, about 0.7 to about 2.0, for example, about 0.7 to about 1.5, about 0.7 to about 1.3 or about 0.8 to about 1.3 of ((D 90 -D 10 ) / D 50 ). D 50 refers to the average diameter (or size) of the particles whose cumulative volume corresponds to 50% by volume in the particle size distribution (e.g., cumulative distribution), and refers to the value of the particle size corresponding to 50% starting from the smallest particles when the total number of particles is 100% in the distribution curve accumulated in the order of the smallest particle size to the largest particle size. D 90 refers to the average diameter (or size) of the particles whose cumulative volume corresponds to 90% by volume in the particle size distribution (e.g., cumulative distribution), and refers to the value of the particle size corresponding to 90% starting from the smallest particles when the total number of particles is 100% in the distribution curve accumulated in the order of the smallest particle size to the largest particle size. D 10 refers to the average diameter (or size) of the particles whose cumulative volume corresponds to 10% by volume in the particle size distribution (e.g., cumulative distribution), and refers to the value of the particle size corresponding to 10% starting from the smallest particles when the total number of particles is 100% in the distribution curve accumulated in the order of the smallest particle size to the largest particle size. Additionally, for example, the single particles can have a D 10 of from about 1.5 μm to about 2.5 μm and a D 90 of from about 5.5 μm to about 6.5 μm. D 50 , D 10 and D 90 can be measured for the positive electrode active material by using a particle size analyzer with a laser diffraction method. If the single particles have a span that satisfies this range, the single particles can have a substantially uniform particle size distribution, which can increase the quality of the positive electrode active material, increase the energy density, and achieve excellent or appropriate initial discharge capacity, initial charge and discharge efficiency, and cycle life characteristics.

[0055] In contrast, the method for preparing the positive electrode active material according to one or more embodiments may further include a process of coating the obtained positive electrode active material. The coating process may be a dry coating or a wet coating. The dry coating is to dry-mix and heat-treat the positive electrode active material and the coating raw material. The temperature of the heat treatment in the dry coating is preferably 600°C to 900°C, and the time of the heat treatment in the dry coating is preferably 2 hours to 20 hours. The wet coating is to add and mix the positive electrode active material and the coating raw material in an aqueous solvent, followed by drying and heat treatment. The temperature of the heat treatment in the wet coating is preferably 600°C to 900°C, and the time of the heat treatment in the wet coating is preferably 2 hours to 20 hours. And the coating element for the coating raw material may be, for example, one or more selected from the group consisting of Al, B, Ca, Ce, Co, Cr, Fe, Mg, Mo, Nb, Si, Ti, Sn, Sr, Ta, V, W, Y, Zn, and Zr.

[0056] In addition, the method for preparing the positive electrode active material may further include mixing the obtained positive electrode active material in the form of single particles with another positive electrode active material in the form of secondary particles (e.g., aggregates of a plurality of primary particles each).

[0057] Positive electrode active material

[0058] In one or more embodiments, the positive electrode active material includes a lithium nickel cobalt composite oxide and is in the form of single particles, wherein the average particle size (D 50 ) is about 0.5 μm to about 8 μm and the span ((D 90 -D 10 ) / D 50 ) value is about 0.7 to about 1.30. The positive electrode active material may be the positive electrode active material prepared by the aforementioned method, and due to the substantially uniform particle size distribution, the positive electrode active material may have excellent or appropriate properties.

[0059] The single particles may have an average particle size (D 50 ) of, for example, about 1 μm to about 6 μm or about 2 μm to about 5 μm, and for example, ((D 90 -D 10 ) / D 50 ) of about 0.7 to about 1.30 or about 0.8 to about 1.30. For example, the single particles may have a D 50 of about 2.5 μm to about 5.0 μm, a D 10 of about 1.5 μm to about 2.5 μm or 1.5 μm to 2.3 μm, and a D 90 of about 5.5 μm to about 6.5 μm or 5.5 μm to 6.3 μm.Some examples of single particles may have, for example, a D of about 2.5 μm to about 3.8 μm or about 2.8 μm to about 3.6 μm 50 If (e.g., when) a single particle has a D that respectively satisfies this range 50 , D 10 , D 90 and ((D 90 - D 10 ) / D 50 ), the single particle may have a substantially uniform particle size distribution, and thus may have excellent or appropriate initial discharge capacity, initial charge and discharge efficiency, cycle life, and energy density characteristics. D 50 , D 10 and D 90 can be measured for the positive electrode active material by a particle size analyzer using the laser diffraction method.

[0060] In this document, the lithium nickel cobalt composite oxide can be represented by Chemical Formula 1 or Chemical Formula 2, etc., as described above. Additionally, the single particle may have the same average particle size and span as described above.

[0061] Furthermore, the positive electrode active material according to one or more embodiments may include single particles and a coating on the surface of the single particles (e.g., each of the single particles), where the coating may include one or more elements selected from the group consisting of Al, B, Ca, Ce, Co, Cr, Fe, Mg, Mo, Nb, Si, Ti, Sn, Sr, Ta, V, W, Y, Zn, and Zr.

[0062] The single particles can be mixed with another positive electrode active material in the form of secondary particles, where based on the total of 100 wt% of the single particles and the secondary particles, the content of the single particles can be about 5 wt% to about 60 wt%, about 5 wt% to about 40 wt%, or about 10 wt% to about 30 wt%.

[0063] In this document, the single particles can exist alone, have no grain boundaries within the particles, consist of one particle, and can be a monolithic structure, an integral structure, or non-aggregated particles, where the particles do not aggregate with each other but exist as independent phases morphologically and can be represented as integral particles or single crystals, e.g., as single crystals. The single particles can exist alone, or the single particles can aggregate / group together. For example, 2 to 10 single particles can aggregate / group and contact each other.

[0064] Positive electrode

[0065] In one or more embodiments, a positive electrode for a rechargeable lithium battery including the aforementioned positive electrode active material is provided. For example, the positive electrode includes a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, and the positive electrode active material layer may include the aforementioned positive electrode active material and may further optionally include a binder, a conductive material, and / or a combination thereof (e.g., any suitable combination).

[0066] Binder

[0067] The binder improves the binding characteristics between the positive electrode active material particles and between the positive electrode active material particles and the positive electrode current collector. Examples of the binder may include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, and nylon.

[0068] Conductive material

[0069] A conductive material (e.g., an electronic conductor) is included to provide electrode (e.g., electronic) conductivity, and any suitable conductive material may be used as the conductive material unless it causes a chemical change. Examples of the conductive material may include: carbonaceous materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.); metallic materials including metal powders or metal fibers such as copper, nickel, aluminum, silver, etc.; conductive polymers (such as polyphenylene derivatives); and / or mixtures thereof (e.g., any suitable mixture).

[0070] Based on 100 wt% of the positive electrode active material layer, the respective contents (e.g., amounts) of the binder and the conductive material may be about 0.5 wt% to about 5 wt%.

[0071] The positive electrode current collector may include Al foil, but the present disclosure is not limited thereto.

[0072] Rechargeable lithium battery

[0073] One or more embodiments may include a rechargeable lithium battery including the aforementioned positive electrode, negative electrode, and electrolyte. As an example, the rechargeable lithium battery may include: a positive electrode, a negative electrode, a separator between the positive electrode and the negative electrode, and an electrolyte solution (i.e., the electrolyte).

[0074] Depending on the shape, the rechargeable lithium battery may be classified as cylindrical, prismatic, pouch-shaped, coin-shaped, etc. Figures 1 to 4Schematic diagrams each showing a rechargeable lithium battery according to one or more embodiments, wherein Figure 1 a cylindrical battery is shown, Figure 2 a prismatic battery is shown, and Figure 3 and Figure 4 a pouch battery is shown. Referring to Figures 1 to 4 , the rechargeable lithium battery 100 includes an electrode assembly 40 and a housing 50 that houses the electrode assembly 40. The electrode assembly 40 has a separator 30 inserted between a positive electrode 10 and a negative electrode 20. The positive electrode 10, negative electrode 20, and separator 30 may be impregnated with an electrolyte solution. As Figure 1 shown, the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. Additionally, in Figure 2 , the rechargeable lithium battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. As Figure 3 and Figure 4 shown, the rechargeable lithium battery 100 includes electrode tabs 70, that is, a positive electrode tab 71 and a negative electrode tab 72 that serve as a circuit path for guiding the current formed in the electrode assembly 40 to the outside.

[0075] Negative electrode

[0076] The negative electrode may include a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector and including a negative electrode active material, and the negative electrode active material layer may further include a binder, a conductive material, and / or a combination thereof (e.g., any suitable combination).

[0077] Negative electrode active material

[0078] The negative electrode active material may include a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, or a transition metal oxide.

[0079] The material that reversibly intercalates / deintercalates lithium ions may include, for example, crystalline carbon, amorphous carbon, and / or a combination thereof (e.g., any suitable combination) as a carbon-based negative electrode active material. The crystalline carbon may be natural graphite or artificial graphite that is amorphous, flaky, sheet-like, spherical, or fibrous (e.g., in the form of fibers). The amorphous carbon may be soft carbon, hard carbon, a mesophase pitch carbonized product, calcined coke, etc.

[0080] The lithium metal alloy includes an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0081] The material capable of doping / undoping lithium can be an Si-based negative electrode active material or an Sn-based negative electrode active material. The Si-based negative electrode active material can include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), an Si-Q alloy (where Q is an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and / or combinations thereof (e.g., any suitable combination), such as Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and / or combinations thereof (e.g., any suitable combination)) and / or combinations thereof (e.g., any suitable combination). The Sn-based negative electrode active material can be Sn, SnO x (0 < x ≤ 2) (e.g., SnO2), an Sn alloy, and / or combinations thereof (e.g., any suitable combination).

[0082] The silicon-carbon composite can be a composite of silicon and amorphous carbon. The average particle size (D 50 ) of the silicon-carbon composite particles can be, for example, about 0.5 μm to about 20 μm. According to one or more embodiments, the silicon-carbon composite can be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite can include secondary particles (cores) in which silicon primary particles are aggregated and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon can also be present between the silicon primary particles. For example, the silicon primary particles can be coated with amorphous carbon. The secondary particles can be dispersed in the amorphous carbon matrix and exist.

[0083] The silicon-carbon composite can further include crystalline carbon. For example, the silicon-carbon composite can include a core containing crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core. The crystalline carbon can be artificial graphite, natural graphite, and / or combinations thereof (e.g., any suitable combination). The amorphous carbon can include soft carbon or hard carbon, mesophase pitch carbonized products, and calcined coke.

[0084] When the silicon-carbon composite includes silicon and amorphous carbon, based on 100 wt% of the silicon-carbon composite, the silicon content (e.g., amount) can be about 10 wt% to about 50 wt%, and the content (e.g., amount) of amorphous carbon can be about 50 wt% to about 90 wt%. Additionally, if (e.g., when) the silicon-carbon composite includes silicon, amorphous carbon, and crystalline carbon, then based on 100 wt% of the silicon-carbon composite, the silicon content (e.g., amount) can be about 10 wt% to about 50 wt%, the content (e.g., amount) of crystalline carbon can be about 10 wt% to about 70 wt%, and the content (e.g., amount) of amorphous carbon can be about 20 wt% to about 40 wt%.

[0085] Additionally, the thickness of the amorphous carbon coating can be about 5 nm to about 100 nm. The average particle diameter (D 50 ) of the silicon particles (primary particles) can be about 10 nm to about 1 μm or about 10 nm to about 200 nm. The silicon particles can exist in the form of elemental silicon, a silicon alloy, or an oxidized form of silicon. The oxidized form of silicon can be represented by SiO x (0 < x ≤ 2). At this time, the atomic content (e.g., amount) ratio of Si:O indicating the degree of oxidation can be about 99:1 to about 33:67. As used herein, if (e.g., when) no other definition is provided, then the average particle diameter (D 50 ) indicates the diameter of the particles in which the cumulative volume in the particle size distribution is about 50 volume%.

[0086] The Si-based negative electrode active material or the Sn-based negative electrode active material can be mixed with the carbon-based negative electrode active material. When the Si-based negative electrode active material or the Sn-based negative electrode active material and the carbon-based negative electrode active material are mixed and used, the mixing ratio can be a weight ratio of about 1:99 to about 90:10.

[0087] Binder

[0088] The binder is used to bond the negative electrode active material particles well to each other and is also used to bond the negative electrode active material to the negative electrode current collector. The binder can be a non-aqueous binder, an aqueous binder, a dry binder, and / or a combination thereof (e.g., any suitable combination).

[0089] The non-aqueous binder can include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, and / or a combination thereof (e.g., any suitable combination).

[0090] The aqueous binder may include styrene-butadiene rubber, (meth)acrylic acid esterified styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, epichlorohydrin polymer, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and / or combinations thereof (e.g., any suitable combination).

[0091] If (e.g., when) the aqueous binder is used as a binder in the negative electrode active material layer, a cellulose compound capable of imparting viscosity may be further included. As the cellulose compound, one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and alkali metal salts thereof may be mixed and used. The alkali metal may be Na, K, or Li.

[0092] The dry binder may be a polymer material capable of becoming fibers and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and / or combinations thereof (e.g., any suitable combination).

[0093] Conductive material

[0094] A conductive material (e.g., an electronic conductor) is included to provide electrode conductivity, and any electrically conductive material may be used as the conductive material unless it causes a chemical change. Examples of the conductive material include: carbonaceous materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.); metallic materials including metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers (such as polyphenylene derivatives); and / or mixtures thereof (e.g., any suitable mixture).

[0095] Based on 100 wt% of the negative electrode active material layer, the content (e.g., amount) of the negative electrode active material may be about 95 wt% to about 99.5 wt%, and based on 100 wt% of the negative electrode active material layer, the content (e.g., amount) of the binder may be about 0.5 wt% to about 5 wt%. For example, the negative electrode active material layer may include about 90 wt% to about 99 wt% of the negative electrode active material, about 0.5 wt% to about 5 wt% of the binder, and about 0.5 wt% to about 5 wt% of the conductive material.

[0096] Negative electrode current collector

[0097] The negative electrode current collector may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof, and may be in the form of a foil, a sheet, or a foam. The thickness of the negative electrode current collector may be, for example, about 1 μm to about 20 μm, about 5 μm to about 15 μm, or about 7 μm to about 10 μm.

[0098] Electrolyte

[0099] For example, the electrolyte for a rechargeable lithium battery may be an electrolyte that may include a non-aqueous organic solvent and a lithium salt.

[0100] The non-aqueous organic solvent serves as a medium for transporting ions participating in the electrochemical reaction of the rechargeable lithium battery. The non-aqueous organic solvent may include carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, and / or combinations thereof (e.g., any suitable combination).

[0101] Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, caprolactone, etc. Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Additionally, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include nitriles (such as R-CN where R is a C2 - C20 straight-chain hydrocarbon group, branched-chain hydrocarbon group, or cycloalkyl group, and may include double bonds, aromatic rings, or ether bonds, etc.); amides (such as dimethylformamide); dioxolanes (such as 1,3-dioxolane, 1,4-dioxolane); sulfolane, etc.

[0102] The non-aqueous organic solvent may be used alone or as a mixture of two or more types (species), and if (e.g., when) used as a mixture of two or more types (species), the mixing ratio may be appropriately or suitably adjusted according to the desired or appropriate battery performance, which is widely understood by those skilled in the art.

[0103] When using carbonate solvents, cyclic carbonates and chain carbonates may be mixed and used, and the cyclic carbonate and the chain carbonate may be mixed in a volume ratio of about 1:1 to about 1:9.

[0104] The non-aqueous organic solvent may further include an aromatic hydrocarbon organic solvent. For example, the carbonate solvent and the aromatic hydrocarbon organic solvent may be mixed and used at a volume ratio of about 1:1 to about 30:1.

[0105] The electrolyte may further include vinylene carbonate, vinylene carbonate or ethylene carbonate compounds to improve the battery cycle life.

[0106] Examples of ethylene carbonate compounds may include fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate and cyanoethylene carbonate.

[0107] The lithium salt dissolved in the non-aqueous organic solvent supplies lithium ions in the battery, ensures the basic operation of the rechargeable lithium battery, and improves the transport of lithium ions between the positive electrode and the negative electrode. Examples of lithium salts may include at least one selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide; LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2)(where x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro bis(oxalate) phosphate (LiDFBOP) and lithium bis(oxalate) borate (LiBOB).

[0108] The concentration of the lithium salt may be in the range of about 0.1 M to about 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate or suitable ionic conductivity and viscosity, so excellent or suitable performance can be achieved, and lithium ions can move effectively.

[0109] Separator

[0110] Depending on the type or kind of the rechargeable lithium battery, the separator may be present between the positive electrode and the negative electrode. The separator may include a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, a polytetrafluoroethylene separator or a multi-layer film of two or more of its layers, such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc.

[0111] The separator may include a porous substrate and a coating on one or two surfaces (e.g., opposite surfaces) of the porous substrate, and the coating includes an organic material, an inorganic material and / or a combination thereof (e.g., any suitable combination).

[0112] The porous substrate may be a polymer film formed from a copolymer or mixture of any one of the following polymers or two or more thereof: polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyaryl ether ketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene ethers, cycloolefin copolymers, polyphenylene sulfides, polyethylene naphthalate, glass fiber, and polytetrafluoroethylene (e.g., Teflon).

[0113] The porous substrate may have a thickness of about 1 μm to about 40 μm, for example, about 1 μm to about 30 μm, about 1 μm to about 20 μm, about 5 μm to about 15 μm, or about 10 μm to about 15 μm.

[0114] The organic material may include a (meth)acrylic copolymer, which includes: a first structural unit derived from (meth)acrylamide; and a second structural unit including at least one of a structural unit derived from (meth)acrylic acid or (meth)acrylate and a structural unit derived from (meth)acrylamidosulfonic acid or a salt thereof.

[0115] The inorganic material may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and / or a combination thereof (e.g., any suitable combination), but the present disclosure is not limited thereto. The average particle size (D 50 ) may be about 1 nm to about 2000 nm, for example, about 100 nm to about 1000 nm or about 100 nm to about 700 nm.

[0116] The organic material and the inorganic material may be mixed in one coating or may exist in the form of a stack of a coating including the organic material and a coating including the inorganic material.

[0117] The thickness of the coating may be about 0.5 μm to about 20 μm, for example, about 1 μm to about 10 μm or about 1 μm to about 5 μm.

[0118] Embodiments and comparative examples of the present disclosure are described in more detail. However, the following embodiments are only examples of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0119] Example 1

[0120] 1. Preparation of the positive electrode active material

[0121] As raw materials, LiOH, NiSO4, CoSO4, and MnSO4 are added to distilled water and mixed such that the molar ratio of Ni:Co:Mn is 50:20:30 and Li / (Ni + Co + Mn) = 1.03, and NH4HCO3 is added and further mixed. The obtained raw material mixture is put into a wet grinding device, and then, it is ground for about 30 minutes at about 3500 rpm using zirconia beads with a diameter of 0.65 mm. The ground composition has particles with an average particle size (D 50 ) of about 0.5 μm or less.

[0122] The ground composition is spray-dried at about 245 °C at 15 mm / min using a spray-drying device to prepare a precursor mixture.

[0123] The precursor mixture is heat-treated in an oxygen atmosphere at 950 °C for 8 hours. Subsequently, the precursor mixture is ground and filtered to prepare a positive electrode active material (Li 1.03 Ni 0.5 Co 0.2 Mn 0.3 O2) according to Example 1. Figure 5 is an SEM image of the positive electrode active material according to Example 1, and Figure 6 is an image magnifying the SEM image. Referring to Figure 5 and Figure 6 , it is demonstrated that the positive electrode active material is in the form of single particles with a substantially uniform particle size distribution.

[0124] 2. Manufacture of a rechargeable lithium battery cell

[0125] 98.5 wt% of the positive electrode active material, 1.0 wt% of a polyvinylidene fluoride binder, and 0.5 wt% of a carbon nanotube conductive material are mixed to prepare a positive electrode active material layer slurry, and the positive electrode active material layer slurry is coated on an aluminum foil current collector, and then, it is dried and pressed to manufacture a positive electrode.

[0126] A polytetrafluoroethylene separator is inserted between the positive electrode and a lithium metal counter electrode to manufacture an electrode assembly, and after inserting the electrode assembly into a battery case, an electrolyte solution prepared by dissolving 1 M LiPF6 in a solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 3:7 is injected into it to manufacture a rechargeable lithium battery cell (half cell) by a conventional method.

[0127] Example 2

[0128] The positive electrode active material and the rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1, except that the raw materials were mixed to have a molar ratio of Ni:Co:Mn = 60:10:30, and the firing temperature was changed to 900 °C.

[0129] Example 3

[0130] The positive electrode active material and the rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1, except that the raw materials were mixed to have a molar ratio of Ni:Co:Mn = 65:5:30, and the firing temperature was changed to 850 °C.

[0131] Example 4

[0132] After preparing the positive electrode active material in substantially the same manner as in Example 1, alumina was dry-mixed with the positive electrode active material such that there was 1 mole part of aluminum based on 100 mole parts of the total metals other than lithium in the positive electrode active material. Then, heat treatment was performed at 850 °C for 8 hours, followed by pulverization and filtration to obtain the coated positive electrode active material. Except for this, the positive electrode active material and the rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1.

[0133] Comparative Example 1

[0134] After preparing nickel hydroxide by a conventional coprecipitation method, the nickel hydroxide was dry-mixed with a lithium raw material and then heat-treated to obtain a positive electrode active material in the form of secondary particles, which was pulverized to obtain a single-particle positive electrode active material.

[0135] For example, nickel sulfate (NiSO4·6H2O), cobalt sulfate (CoSO4·7H2O), and manganese sulfate (MnSO4·H2O) with a molar ratio of Ni:Co:Mn = 55:15:30 were added to distilled water to prepare a mixed metal raw material solution. Additionally, ammonia water (NH4OH) and sodium hydroxide (NaOH) as a precipitating agent were prepared to form a complex compound.

[0136] First, ammonia water with a concentration of 0.25 M was placed in a reactor. Subsequently, at a reaction temperature of 50 °C and a stirring power of 3.0 kW / m 3 the mixed metal raw material solution and the complexing agent were added thereto at 142 mL / min and 34 mL / min, respectively, to start the reaction. The reaction was carried out for 30 hours while adding NaOH to maintain the pH. If (for example, when) the average particle size of the obtained particles reached about 14 μm, the reaction was terminated. The obtained product was rinsed and then dried with hot air at about 150 °C for 24 hours to prepare the precursor Ni 0.55 Co 0.15 Mn0.30 (OH)2。

[0137] The precursor and Li2CO3 were dry-mixed at a molar ratio of Li / (Ni + Co + Mn) = 1.03, and the mixture was heat-treated at 920 °C for 8 hours to obtain a lithium nickel cobalt manganese composite oxide in the form of secondary particles. The secondary particles were pulverized using a jet mill to have an average particle size (D 50 ) of about 2.5 μm to obtain a single-particle positive electrode active material (Li 1.03 Ni 0.55 Co 0.15 Mn 0.30 O2).

[0138] Comparative Example 2

[0139] The positive electrode active material and the rechargeable lithium battery cell were produced in substantially the same manner as in Comparative Example 1, except that the raw materials were mixed to have a molar ratio of Ni:Co:Mn = 60:10:30, and the firing temperature was changed to 900 °C.

[0140] Comparative Example 3

[0141] The positive electrode active material and the rechargeable lithium battery cell were produced in substantially the same manner as in Comparative Example 1, except that the raw materials were mixed to have a molar ratio of Ni:Co:Mn = 62:6:32, and the firing temperature was changed to 850 °C.

[0142] Comparative Example 4

[0143] Li2CO3, NiCO3, CoCO3, and MnCO3 as raw materials were dry-mixed at a molar ratio of Ni:Co:Mn = 60:10:30 and a molar ratio of Li / (Ni + Co + Mn) = 1.03. The obtained mixture was heat-treated at 900 °C in an oxygen atmosphere for 8 hours to prepare the positive electrode active material according to Comparative Example 4. Except for this, the positive electrode active material and the rechargeable lithium battery cell were produced in substantially the same manner as in Example 1.

[0144] Evaluation Example 1: Evaluation of Particle Size Distribution

[0145] The particle size distribution of each of the positive electrode active materials of Examples 1 to 4 and Comparative Examples 1 to 4 was analyzed using a particle size analyzer utilizing the laser diffraction method, and the results are shown in Table 1.

[0146] Table 1

[0147] <![CDATA[D 50 > <![CDATA[D 10 > <![CDATA[D 90 > <![CDATA[(D 90 -D 10 ) / D 50 > Example 1 3.3 1.6 5.7 1.24 Example 2 3.2 1.6 5.6 1.25 Example 3 3.2 1.6 5.7 1.28 Example 4 3.3 1.6 5.6 1.21 Comparative Example 1 3.9 1.2 6.8 1.44 Comparative Example 2 4 1.2 6.9 1.43 Comparative Example 3 4.2 1.3 7 1.36 Comparative Example 4 4.1 1.4 6.8 1.32

[0148] Referring to Table 1, the Examples satisfy D of 2.5 μm to 5.0 μm50 , D from 1.5 μm to 2.5 μm 10 , D from 5.5 μm to 6.5 μm 90 , and ((D 90 - D 10 ) / D 50 ) is 1.28 or less, and thus each has a substantially very uniform particle size distribution.

[0149] Evaluation Example 2: Evaluation of Initial Charge / Discharge Capacity, Efficiency, and Cycle Life Characteristics

[0150] The rechargeable lithium battery cells of Examples 1 to 3 and Comparative Examples 1 to 4 were charged at a constant current of 0.2C to 4.45V and then charged at a constant voltage to 0.05C, and then discharged at 0.2C to 3.0V at 25°C for initial charge and discharge. In Table 2, the initial charge capacity and the initial discharge capacity are provided, and the latter is provided as the efficiency with respect to the initial charge and discharge efficiency of the former.

[0151] Subsequently, at 45°C, in the voltage range of 3.0V to 4.45V, the rechargeable lithium battery cells were repeatedly charged and discharged 50 times at 1.0C. In Table 2, the ratio of the discharge capacity after the 50th cycle to the initial discharge capacity is calculated and provided as the cycle life.

[0152] Table 2

[0153]

[0154] Referring to Table 2, Examples 1 to 3 each achieved high initial discharge capacity, initial charge and discharge efficiency, and cycle life characteristics. Compared with Comparative Example 1 having a slightly higher nickel content (e.g., amount), Example 1 exhibited much higher initial discharge capacity, initial charge and discharge efficiency, and cycle life characteristics. Comparing Example 2 and Comparative Example 2 having the same nickel content (e.g., amount), as the initial discharge capacity increased, Example 2 exhibited an increased initial discharge capacity and improved cycle life characteristics compared with Comparative Example 2. Similarly, Example 3 having a nickel content (e.g., amount) similar to that of Comparative Example 3 showed improved initial charge and discharge efficiency and significantly improved cycle life characteristics due to a slightly increased initial discharge capacity. Comparative Example 4 using the same raw materials as Examples 1 to 3 but adopting a comparable solid-phase mixing method showed low initial charge and discharge efficiency, especially deteriorated cycle life characteristics due to a low initial discharge capacity.

[0155] Accordingly, it has been confirmed that the method for preparing the positive electrode active material according to one or more embodiments not only significantly reduces the production and processing costs due to the omission (e.g., not including or excluding) of the precursor synthesis process and the overall simple method, but also provides a single-particle positive electrode active material having a substantially uniform particle size distribution, and achieves more excellent or appropriate initial discharge capacity, initial charge and discharge efficiency, and cycle life characteristics in the high voltage region. That is, as described in a specific embodiment, the method for producing the positive electrode active material has been confirmed to significantly reduce the production and processing costs. This cost reduction is achieved by bypassing the precursor synthesis process and adopting a more direct method. In addition, the single-particle positive electrode active material produced by this method exhibits a consistent particle size distribution and provides excellent performance especially in terms of initial discharge capacity, initial charge and discharge efficiency, and cycle life characteristics in high voltage applications.

[0156] In view of the overall content of the present disclosure, those skilled in the art will recognize that the appropriate features of the various embodiments of the present disclosure can be partially or completely combined or combined with each other, and can be technically interlocked and operated in various suitable ways, and unless otherwise stated or implied, the various embodiments can be implemented independently of each other or combined with each other in any appropriate way.

[0157] In the context of the present application, and unless otherwise defined, the terms "use", "using", and "used" can be regarded as synonyms of the terms "utilize", "utilizing", and "utilized", respectively.

[0158] Further, when describing the embodiments of the inventive concept, the use of "may" refers to "one or more embodiments of the inventive concept". Also, the term "exemplary" is intended to indicate an example or illustration.

[0159] The battery manufacturing apparatus, battery management system (BMS) apparatus, and / or any other relevant apparatus or components according to embodiments of the present invention described herein may be implemented using any suitable hardware, firmware (e.g., application specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of the apparatus may be formed on a single integrated circuit (IC) chip or on separate IC chips. Further, the various components of the apparatus may be implemented on a flexible printed circuit film, tape carrier package (TCP), or printed circuit board (PCB), or formed on a substrate. Further, the various components of the apparatus may be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions, and interacting with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which may be implemented using standard memory devices (such as, by way of example, random access memory (RAM)) in the computing device. The computer program instructions may also be stored in other non-transitory computer-readable media (such as, by way of example, CD-ROM, flash drive, etc.). And, those skilled in the art should recognize that, without departing from the scope of the present disclosure, the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a particular computing device may be distributed over one or more other computing devices.

[0160] Although the present invention has been described in connection with exemplary embodiments presently considered to be practical, it is to be understood that the disclosure is not limited to the disclosed embodiments. On the contrary, the disclosure is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the claims and their equivalents.

Claims

1. A method for preparing a positive electrode active material, comprising: adding lithium hydroxide, nickel sulfate, cobalt sulfate, and ammonium carbonate to an aqueous solvent and mixing them to prepare a raw material mixture; subjecting the raw material mixture to wet grinding; spray-drying the ground raw material mixture to obtain a positive electrode active material precursor mixture; and heat-treating the positive electrode active material precursor mixture to obtain a positive electrode active material in the form of single particles, the positive electrode active material comprising a lithium nickel cobalt composite oxide.

2. The method according to claim 1, wherein manganese sulfate, aluminum hydroxide, alumina, or a combination thereof is further mixed in the raw material mixture.

3. The method according to claim 1, wherein a dopant raw material is further mixed in the raw material mixture, and the dopant raw material comprises B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zr, or a combination thereof.

4. The method according to claim 1, wherein the wet grinding is performed using a zirconia ball mill at 2000 rpm to 5000 rpm for 5 minutes to 120 minutes.

5. The method according to claim 1, wherein When the raw material mixture is wet - ground, the particles of the ground raw material mixture are ground until the average particle size D 50 is less than or equal to 0.5 μm.

6. The method according to claim 1, wherein the spray-drying is performed by setting the hot air temperature to 200°C to 300°C and setting the hot air discharge temperature to 100°C to 150°C.

7. The method according to claim 1, wherein the heat treatment of the positive electrode active material precursor mixture is performed in an oxygen atmosphere at a temperature range of 800°C to 1000°C for 4 hours to 24 hours.

8. The method according to claim 1, wherein the obtained lithium nickel cobalt composite oxide is represented by Chemical Formula 1: Chemical Formula 1 Li a1 Ni x1 Co y1 M 1 z1 O 2-b1 X b1 , Among them, In Chemical Formula 1, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 < 1, 0 < y1 ≤ 0.7, 0 ≤ z1 ≤ 0.4, 0.9 ≤ x1 + y1 + z1 ≤ 1.1, and 0 ≤ b1 ≤ 0.1, M 1 is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from F, P, and S.

9. The method according to claim 8, wherein the obtained lithium nickel cobalt composite oxide is represented by Chemical Formula 2: Chemical Formula 2 Li a2 Ni x2 Co y2 M 2 z2 M 3 w2 O 2-b2 X b2 , Among them, In Chemical Formula 2, 0.9 ≤ a2 ≤ 1.8, 0.3 ≤ x2 ≤ 0.98, 0.01 ≤ y2 ≤ 0.4, 0.01 ≤ z2 ≤ 0.4, 0 ≤ w2 ≤ 0.1, 0.9 ≤ x2 + y2 + z2 + w2 ≤ 1.1, and 0 ≤ b2 ≤ 0.1, M 2 is Al, Mn, or a combination thereof, M 3 is one or more elements selected from B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from F, P, and S.

10. The method according to claim 1, wherein The average particle size D of the prepared single particles 50 is 0.5 μm to 8 μm.

11. The method according to claim 1, wherein The (D 90 -D 10 ) / D 50 value of the prepared single particles is 0.7 to 2.0, D 10 : The average diameter of the prepared single particles corresponding to 10% by volume of the cumulative volume in the particle size distribution, D 50 : the average diameter of the single particles prepared in which the cumulative volume in the particle size distribution corresponds to 50% by volume, and D 90 : The average diameter of the prepared single particles corresponding to 90% by volume of the cumulative volume in the particle size distribution.

12. The method according to claim 1, further comprising: coating the obtained positive electrode active material.

13. The method according to claim 12, wherein the coating comprises: dry mixing and heat-treating the positive electrode active material and a coating raw material; or adding and mixing the positive electrode active material and a coating raw material in an aqueous solvent, followed by drying and heat-treating.

14. The method according to claim 13, wherein the coating elements used in the coating raw material comprise Al, B, Ca, Ce, Co, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, Zn, Zr, or a combination thereof.

15. A positive electrode active material, comprising: a lithium nickel cobalt composite oxide in the form of single particles, wherein D of the single particle 50 is 0.5 μm to 8 μm, and (D 90 - D 10 ) / D 50 value is 0.7 to 1.30, D 10 : The average diameter of the prepared single particles in which the cumulative volume in the particle size distribution corresponds to 10% by volume, D 50 : the average diameter of the prepared single particles in which the cumulative volume in the particle size distribution corresponds to 50% by volume, and D 90 : The average diameter of the prepared single particles corresponding to 90% by volume of the cumulative volume in the particle size distribution.

16. The positive electrode active material according to claim 15, wherein The single particle has a D of 2.5 μm to 5.0 μm 50 、a D of 1.5 μm to 2.5 μm 10 and a D of 5.5 μm to 6.5 μm 90 .

17. A rechargeable lithium battery, comprising A positive electrode, comprising a positive electrode active material prepared by the method according to any one of claims 1 to 14 or comprising the positive electrode active material according to claim 15 or claim 16; A negative electrode; and An electrolyte.

Images