Method for preparing positive electrode active material and rechargeable lithium battery

Abstract

The invention relates to a method for preparing a positive electrode active material and a rechargeable lithium battery. The method may include: performing a co-precipitation reaction of a mixture of a nickel precursor and a metal precursor to obtain a nickel-based composite hydroxide having an average particle diameter of about 10 [mu] m to about 20 [mu] m, the co-precipitation reaction including a first step of reacting at a pH range of about pH 11 to about pH 12 and a second step of reacting at a pH lower than the first step; mixing a nickel-based composite hydroxide, anhydrous lithium hydroxide, an aluminum raw material, and a zirconium raw material, and performing a first heat treatment to produce a secondary particle including a layered lithium-nickel-based composite oxide and aggregating a plurality of primary particles, the secondary particle being a hollow secondary particle having pores therein; crushing the secondary particles; and adding and mixing the pulverized resultant, a cobalt coating raw material, and a zirconium coating raw material to an aqueous (e.g., water-soluble) solvent, and then performing a second heat treatment to obtain the positive electrode active material.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0055654, filed with the Korean Intellectual Property Office on April 25, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] One or more embodiments of this disclosure relate to a method for preparing a positive electrode active material and a rechargeable lithium battery. Background Technology

[0004] Portable information devices (such as cellular phones, laptops, smartphones, etc.) or electric vehicles utilize rechargeable lithium batteries with high energy density and portability as power sources. Research has been conducted on using rechargeable lithium batteries with high energy density as power sources and / or energy storage sources for hybrid or electric vehicles.

[0005] To achieve rechargeable lithium batteries suitable for these purposes, one or more positive electrode active materials have been considered. Among them, lithium nickel composite oxides, lithium nickel manganese cobalt composite oxides, lithium nickel cobalt aluminum composite oxides, and lithium cobalt composite oxides are mainly or predominantly used as positive electrode active materials.

[0006] However, with the increasing demand for larger size, higher capacity, higher energy density and / or improved or increased yield of rechargeable lithium batteries, there is a desire to develop methods for preparing suitable positive electrode active materials. Summary of the Invention

[0007] One or more aspects of embodiments of this disclosure relate to a method for effectively or suitably preparing a positive electrode active material comprising core particles in the form of single particles at relatively low heat treatment (e.g., sintering) temperatures without the use of an alkaline grain growth promoter.

[0008] One or more aspects of the embodiments of this disclosure relate to methods for reducing particle aggregation and simplifying and making the entire preparation process more economical.

[0009] One or more aspects of embodiments of this disclosure relate to a method for preparing a positive electrode active material, the method comprising: co-precipitating a mixture of a nickel precursor and a metal precursor to obtain a nickel-based composite hydroxide with an average particle size of about 10 μm to about 20 μm, the co-precipitation reaction comprising a first step of reacting at a pH range of about pH 11 to about pH 12 and a second step of reacting at a pH lower than that of the first step; mixing the nickel-based composite hydroxide, anhydrous lithium hydroxide, an aluminum raw material and a zirconium raw material and subjecting it to a first heat treatment to produce secondary particles comprising layered lithium-nickel composite oxide and composed of aggregates of multiple primary particles, the secondary particles being hollow secondary particles having internal pores; pulverizing the secondary particles; and adding the pulverized result (e.g., the pulverized secondary particles), a cobalt coating raw material and a zirconium coating raw material to an aqueous (e.g., water-soluble) solvent and mixing, followed by a second heat treatment to obtain the positive electrode active material.

[0010] The method for preparing positive electrode active materials according to one or more embodiments can efficiently (e.g., in terms of processing or economy) prepare positive electrode active materials comprising core particles in the form of single particles at relatively low firing temperatures without the use of alkaline grain growth promoters, and can reduce particle aggregation (e.g., the degree or occurrence of particle aggregation), and can prepare structurally stable positive electrode active materials that are free of or substantially free of residual impurities, without increasing impedance (e.g., resistance) (or reducing the degree of impedance (e.g., resistance) occurrence), and can have a long cycle life while reducing particle aggregation (e.g., reducing the degree of particle aggregation occurrence) and making the entire preparation process simple and economical. Attached Figure Description

[0011] The accompanying drawings, together with the specification, illustrate embodiments of the subject matter of this disclosure and, together with the description, serve to explain the principles of embodiments of the subject matter of this disclosure.

[0012] Figures 1-4 Each of the above is a schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments.

[0013] Figure 5 Image of a cross-section of the hollow secondary particles prepared in Example 1, taken using a scanning electron microscope (SEM).

[0014] Figure 6 This is an image of a cross-section of the small secondary particles prepared in Comparative Example 3, taken using a scanning electron microscope.

[0015] Figure 7 This is an image of the cross-section of the secondary particles (large particles) prepared in Comparative Example 4, taken using a scanning electron microscope.

[0016] Figure 8The graphs illustrate the cycle life characteristics of the rechargeable lithium battery cells manufactured in Examples 1 and 2, and Comparative Examples 1 to 4.

[0017] Figure 9 Photographs illustrating the results of the loading test of the positive electrode active material prepared according to Example 1.

[0018] Figure 10 A photograph illustrating the results of the loading test of the positive electrode active material prepared according to Comparative Example 3.

[0019] Figure 11 A photograph illustrating the results of the loading test of the positive electrode active material prepared according to Comparative Example 4.

[0020] Explanation of reference numerals in the attached figures

[0021] 100: Rechargeable lithium battery; 10: Positive electrode

[0022] 11: Positive electrode lead connector 12: Positive electrode terminal

[0023] 20: Negative electrode 21: Negative electrode lead connector

[0024] 22: Negative electrode terminal; 30: Diaphragm

[0025] 40: Electrode assembly; 50: Housing

[0026] 60: Sealing component; 70: Electrode terminal piece

[0027] 71: Positive electrode connector; 72: Negative electrode connector Detailed Implementation

[0028] Embodiments of this disclosure will be described in more detail below. However, these embodiments are illustrative, and this disclosure is not limited thereto, and is defined by the scope of the claims and their equivalents.

[0029] Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” as used herein are intended to also include the plural forms. Furthermore, when describing embodiments of this disclosure, the word “may” refers to “one or more embodiments of this disclosure.”

[0030] In the context of this disclosure, unless otherwise specified, the terms “use,” “using,” and “used” are to be regarded as synonyms with the terms “utilize,” “utilizing,” and “utilized,” respectively.

[0031] As used herein, the term “about” and similar terms are used as terms of approximation and not as terms of degree, and are intended to describe the inherent deviations of measured or calculated values ​​that will be recognized by one of ordinary skill in the art. “About” or “approximation” as used herein also includes stated values ​​and means within an acceptable range of deviation for a particular value, as determined by one of ordinary skill in the art, taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0032] Any numerical range set forth herein includes all subranges with the same numerical precision contained within the set forth range. For example, the range “1.0 to 10.0” is intended to include all subranges between the stated minimum value of 1.0 and the stated maximum value of 10.0 (and inclusive of both), that is, a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Any maximum numerical limit set forth herein is intended to include all lower numerical limits contained herein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits contained herein. Accordingly, the applicant reserves the right to amend this specification (including the appended claims) to expressly set forth any subranges contained within the range expressly set forth herein.

[0033] As used herein, unless otherwise specifically defined, it will be understood that if an element (such as a layer, film, region, substrate, etc.) is referred to as being "on" another element (such as a layer, film, region, substrate, etc.), it may be directly on the other element (such as a layer, film, region, substrate, etc.), or an intermediary element may be present. In contrast, if an element (such as a layer, film, region, substrate, etc.) is referred to as being "directly on" another element (such as a layer, film, region, substrate, etc.), an intermediary element may not be present.

[0034] As used herein, the singular may also include the plural if (e.g., when) no specific definition is otherwise provided. In one or more embodiments, unless otherwise indicated, “A or B” may mean “including A, including B, or including both A and B”.

[0035] As used herein, “combinations thereof” may refer to mixtures, stacks, complexes, copolymers, alloys, blends and / or reaction products of the components.

[0036] If (for example, when) no other definition is provided, the particle size as used herein may be the average particle size. This average particle size refers to the average particle size (D).50 The average particle size (D) is the diameter of particles that constitute 50% of the total volume in the particle size distribution. 50 The particle size distribution (D) can be measured using methods commonly used or available to those skilled in the art, for example, by using a particle size analyzer and / or transmission electron microscopy (TEM) and / or scanning electron microscopy (SEM). In one or more embodiments, a dynamic light scattering (DLS) measurement device can be used for data analysis, and the number of particles can be counted for each particle size range. Based on this information, the average particle size (D) can be calculated. 50 The value can also be obtained using laser diffraction. If, for example, the measurement is performed by laser diffraction, the particles to be measured can be dispersed in a dispersion medium and then introduced into a commercially available laser diffraction particle size analyzer (e.g., the MT 3000 available from Microtrac, Ltd.). After irradiation with ultrasound at 60 W output and approximately 28 kHz, the average particle size (D) based on a 50% volume percentage of the particle size distribution in the analyzer can be calculated. 50 ).

[0037] In this document, it should be understood that terms such as “comprising,” “including,” or “having” are intended to indicate the presence of the features, quantities, steps, elements, or combinations thereof embodied, but do not preclude the possibility of the presence or addition of one or more other features, quantities, steps, elements, or combinations thereof.

[0038] The term "metal" is defined as encompassing common metals, transition metals, and quasi-metals (semi-metals).

[0039] Methods for preparing positive electrode active materials

[0040] In one or more embodiments, a method for preparing a positive electrode active material may include: (i) co-precipitating a mixture of a nickel precursor and a metal precursor to obtain a nickel-based composite hydroxide with an average particle size of about 10 μm to about 20 μm, the co-precipitation reaction including a first step of reacting at a pH range of about pH 11 to about pH 12 and a second step of reacting at a pH lower than that of the first step; (ii) mixing the nickel-based composite hydroxide, anhydrous lithium hydroxide, an aluminum raw material and a zirconium raw material and subjecting it to a first heat treatment to produce secondary particles comprising layered lithium-nickel composite oxide and composed of aggregates of multiple primary particles, the secondary particles being hollow secondary particles with internal pores; (iii) pulverizing the secondary particles; and (iv) adding the pulverized result (e.g., the pulverized secondary particles), a cobalt coating raw material and a zirconium coating raw material to an aqueous (e.g., water-soluble) solvent and mixing, followed by a second heat treatment to obtain the positive electrode active material.

[0041] High-nickel positive electrode active materials with a nickel content (e.g., amount) of about 60 mol% or higher have been developed because they can achieve high energy density, but they have limitations due to one or more problems, such as structural degradation due to charging and discharging, surface side reactions with the electrolyte, and degradation due to particle breakage.

[0042] Because high-nickel positive electrode active materials can achieve or provide high capacity, secondary particle forms, made by aggregating multiple primary particles, have been primarily or dominantly used. However, the use of single-particle forms remains desirable for achieving long cycle life and reducing gas generation. However, increasing the sintering temperature to produce single particles can lead to problems such as increased particle aggregation and reduced yield. To eliminate or reduce particle aggregation (e.g., the degree or occurrence of aggregation) and lower the sintering temperature, research has focused on adding basic grain growth promoters during the synthesis of single particles. However, a problem exists that residual basic grain growth promoters after sintering can act as impedance (e.g., resistance) within the positive electrode, resulting in reduced cycle life. If (e.g., when) a rinsing process is performed to remove or reduce residual basic grain growth promoters or residual salts, the preparation cost may increase, and the process may become complex.

[0043] Accordingly, in one or more embodiments, this disclosure provides a method for preparing a positive electrode active material that can be effectively synthesized even by heat treatment at relatively low temperatures. The positive electrode active material can be economical and advantageous or beneficial relative to large-scale production, and can achieve or provide excellent or suitable cycle life characteristics due to its high structural stability.

[0044] According to the preparation method described in one or more embodiments of this disclosure, high-nickel positive electrode active materials can be effectively or appropriately prepared into single particles at relatively low firing temperatures using a simple method without the addition of alkaline grain growth promoters, thereby improving or increasing yield and economic benefits.

[0045] In a method for preparing a positive electrode active material according to one or more embodiments, if (e.g., when) a nickel-based composite hydroxide and anhydrous lithium hydroxide are mixed and subjected to a first heat treatment, aluminum and zirconium raw materials can be added together and calcined. It should be understood that the aluminum and zirconium raw materials can act as dopants and simultaneously as grain growth promoters. If (e.g., when) aluminum and zirconium raw materials are added, this addition can promote or enhance grain growth, effectively or appropriately synthesizing single particles at a lower temperature than that of commonly used or generally available single-particle synthesis methods. Accordingly, particle aggregation (e.g., the degree or occurrence of particle aggregation) can be suppressed or reduced during the preparation process, and the yield can be improved or increased. Commonly used or generally available alkaline grain growth promoters or co-solvents have the problem of post-calcination residues (e.g., undesirable impurities), which act as impedance (e.g., resistance) within the positive electrode, thereby reducing cycle life. However, by using aluminum and zirconium raw materials as dopants in the positive electrode active material, cycle life characteristics can be improved or increased.

[0046] The following describes in more detail the implementation of the method for preparing the positive electrode active material.

[0047] (i) First, a nickel-based composite hydroxide with an average particle size of about 10 μm to about 20 μm can be prepared by coprecipitation reaction, which includes a first step of reacting a mixture of nickel precursor and metal precursor in a pH range of about pH 11 to about pH 12 and a second step of reacting at a pH lower than that of the first step.

[0048] Nickel-based complex hydroxides can serve as precursors for the core particles in positive electrode active materials and can be synthesized via coprecipitation reactions. In these coprecipitation reactions, the nickel precursor can be a nickel hydroxide, oxide, nitrate, sulfate, carbonate, or a combination thereof. The metal precursor can be a metal-containing hydroxide, oxide, nitrate, sulfate, carbonate, or a combination thereof. In this paper, the metal precursor can be boron (B), barium (Ba), calcium (Ca), cerium (Ce), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), niobium (Nb), silicon (Si), tin (Sn), strontium (Sr), titanium (Ti), vanadium (V), tungsten (W), yttrium (Y), zinc (Zn), or a combination thereof.

[0049] In one or more embodiments, in addition to nickel and metal precursors, complexing agents and / or pH adjusters may be used in the coprecipitation reaction. Complexing agents can play a role in controlling or adjusting the reaction rate of precipitation formation in the coprecipitation reaction and may include, for example, ammonia (NH4OH), citric acid, and / or combinations thereof. The concentration of the complexing agent may be from about 0.1 M to about 1.5 M, for example, from about 0.1 M to about 1.4 M or from about 0.5 M to about 1.4 M. pH adjusters can be used to control or adjust the pH of the reactants and may include, for example, sodium hydroxide (NaOH), sodium carbonate (Na2CO3), sodium oxalate (Na2C2O4), and / or combinations thereof.

[0050] The coprecipitation reaction may include a first step reacting at a pH range of about 11 to about 12 and a second step reacting at a pH lower than that of the first step. The pH of the first step may be, for example, about 11.5 to about 12, about 11.6 to about 11.9, or about 11.7 to about 11.8, and may be considered a pore-forming step (or type of pore-forming step). The second step may be a step reacting at a pH lower than that of the first step, and may be a particle growth step (or type of pore-forming step). By changing the pH in two or more steps, the synthesis rate can be altered, resulting in nickel-based composite hydroxides with micropores within the particles. The pH of the second step may be, for example, about 10 to about 11.9, about 10.5 to about 11.7, about 11 to about 11.7, about 11.2 to about 11.6, or about 11.3 to about 11.6. The pH difference between the first step and the second step can be, for example, about 0.1 to about 1.5 (e.g., about 0.1 to about 1.0, about 0.1 to about 0.8, about 0.1 to about 0.6, about 0.1 to about 0.5, about 0.1 to about 0.3 or about 0.1 to about 0.2).

[0051] As an example, the first step can take approximately 6 to 12 hours or approximately 8 to 10 hours. The second step can take approximately 10 to 30 hours, approximately 15 to 25 hours, or approximately 18 to 24 hours.

[0052] For example, nickel-based complex hydroxides can be represented by chemical formula 1.

[0053] Chemical Formula 1

[0054] Ni x1 M 1 y1 (OH)2

[0055] In chemical formula 1, 0.6 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.4, 0.9 ≤ x1 + y1 ≤ 1.1, and M 1may be one or more elements selected from B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zn.

[0056] In Chemical Formula 1, 0.7 ≤ x1 ≤ 1 and 0 < y1 ≤ 0.3, or 0.8 ≤ x1 ≤ 1 and 0 ≤ y1 ≤ 0.2, or 0.9 ≤ x1 < 1 and 0 < y1 ≤ 0.1.

[0057] For example, the nickel-based composite hydroxide may be represented by Chemical Formula 2.

[0058] Chemical Formula 2

[0059] Ni x2 Co v2 M 2 y2 (OH)2

[0060] In Chemical Formula 2, 0.6 ≤ x2 < 1, 0 < v2 ≤ 0.4, 0 ≤ y2 ≤ 0.4, and 0.9 ≤ x2 + v2 + y2 ≤ 1.1, and M 2 may be one or more elements selected from B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zn.

[0061] For example, in the nickel-based composite hydroxide, based on 100 mol% of the total metals other than lithium, the nickel content (e.g., amount) may be greater than or equal to about 60 mol%, greater than or equal to about 65 mol%, greater than or equal to about 70 mol%, greater than or equal to about 75 mol%, greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol% or less than or equal to about 98 mol%.

[0062] The nickel-based composite hydroxide may be in the form of particles. For example, the particles may include an inner part including many micropores and / or an outer part surrounding the inner part and having a dense structure. Here, the inner part of the nickel-based composite hydroxide particles may refer to a region of 50 vol% to 70 vol% (e.g., 60 vol%) from the center of the particles, or may refer to the remaining region other than the outer part, and the outer part may be a region within 3 μm from the outermost surface in the total distance from the center to the surface of the particles.

[0063] Thus, by using the nickel-based composite hydroxide having micropores inside the particles, a structure in the form of hollow secondary particles can be effectively or suitably obtained. In this case, during the pulverization process, the secondary particles can be easily pulverized to obtain single particles.

[0064] The average particle size (D) of nickel-based complex hydroxides 50 The average particle size can be approximately 10 μm to approximately 20 μm, for example, approximately 10 μm to approximately 18 μm or approximately 12 μm to approximately 16 μm. Here, the average particle size (D) is... 50 It can be measured using SEM images. Nickel-based complex hydroxides can be large particles, for example, large particle precursors.

[0065] For example, nickel-based complex hydroxides can be amorphous (e.g., non-crystalline), which can be confirmed by X-ray diffraction analysis.

[0066] Next, (ii) the nickel-based composite hydroxide, anhydrous lithium hydroxide, aluminum raw material, and zirconium raw material can be mixed and subjected to a first heat treatment. This produces secondary particles comprising layered lithium-nickel composite oxides, the secondary particles being aggregates of multiple primary particles and being hollow secondary particles with internal pores.

[0067] As an example, in process (ii) above, based on 1 mole of total metals in the nickel-based complex hydroxide, aluminum from the aluminum feedstock, and zirconium from the zirconium feedstock, the lithium content (e.g., amount) of the anhydrous lithium hydroxide can be about 0.9 moles to about 1.2 moles, for example, about 0.9 moles to about 1.1 moles or about 0.9 moles to about 1.05 moles, for example, greater than about 1 mole and less than about 1.1 moles, for example, about 1.01 moles to about 1.04 moles. By suitably or appropriately controlling or adjusting the molar ratio of the lithium feedstock, core particles with stable structure and good or appropriate quality in the form of single particles can be effectively or appropriately prepared.

[0068] In process (ii) above, anhydrous lithium hydroxide can be used as a lithium feedstock. By using anhydrous lithium hydroxide as a lithium feedstock, the loading can be increased, which helps to improve or increase the hourly output.

[0069] For example, anhydrous lithium hydroxide (LiOH) can be produced by drying the average particle size (D). 50 The hydrated lithium hydroxide (LiOH·H2O) has a particle size of approximately 400 μm to approximately 600 μm and is pulverized into particles with an average particle size of approximately 3 μm to approximately 30 μm (D). 50 Anhydrous lithium hydroxide is prepared by means of the following method. It may not be pulverized before drying, but only pulverized once for about 1 minute after drying. Drying can be carried out, for example, under vacuum conditions at a temperature range of about 50°C to about 200°C for about 0.5 hours to about 20 hours.

[0070] Methods for preparing anhydrous lithium hydroxide can readily produce anhydrous lithium salts, maintain optimal or appropriate process conditions, and reduce the conversion rate to Li₂CO₃ to about 5% or less, thereby obtaining high-purity anhydrous lithium hydroxide. After pulverizing anhydrous lithium hydroxide, additional processing may be difficult due to the rapid decrease in powder flowability. For example, if drying is performed after pulverization, fine particles may entangle and aggregate due to the heat generated during drying, potentially requiring a re-pulverization process. However, the aggregated particles may be more difficult to grind due to their high aggregation strength in the re-pulverization process. In one or more embodiments, the conversion rate to Li₂CO₃ may also increase with the increase in the number of processes due to the increase in specific surface area, thus failing to obtain high-quality anhydrous lithium hydroxide. However, the method for preparing anhydrous lithium hydroxide according to one or more embodiments, wherein the anhydrous lithium hydroxide is pulverized to a specific size under set or predetermined conditions after drying, can be a simple method for obtaining high-quality anhydrous lithium hydroxide, and in one or more embodiments, additional processes can be readily or appropriately added thereto.

[0071] By using anhydrous lithium hydroxide instead of hydrated lithium hydroxide as the lithium feedstock, the amount of unnecessary or undesirable gases and moisture generated during the first heat treatment process can be reduced, thereby improving or enhancing processability and the quality of the positive electrode active material. In one or more embodiments, unnecessary or undesirable heavy materials (such as H2O) can be omitted to increase heat treatment yield and improve or enhance productivity.

[0072] The average particle size (D) of hydrated lithium hydroxide as the starting material 50 The anhydrous lithium hydroxide may have a particle size of, for example, about 450 μm to about 550 μm or about 480 μm to about 500 μm, but the obtained anhydrous lithium hydroxide may have an average particle size of about 3 μm to about 25 μm or about 5 μm to about 20 μm (D). 50 ).

[0073] In one or more embodiments, based on 100 mol% of total metals of nickel-based complex hydroxide, aluminum of aluminum raw material and zirconium of zirconium raw material, the aluminum content (e.g., amount) of aluminum raw material may be about 0.8 mol% to about 1.5 mol%, for example, about 0.8 mol% to about 1.4 mol%, about 0.8 mol% to about 1.3 mol%, or about 0.9 mol% to about 1.2 mol%.

[0074] For example, based on 100 mol% of total metals in nickel-based complex hydroxides, aluminum raw materials, and zirconium raw materials, the zirconium content (e.g., amount) of the zirconium raw materials can be about 0.1 mol% to about 0.3 mol%, for example, about 0.1 mol% to about 0.2 mol%.

[0075] In one or more embodiments, the molar ratio (Al / Zr) of aluminum content (e.g., amount) to zirconium content (e.g., amount) may be greater than or equal to about 5, for example, about 5 to about 20, about 5 to about 15, or about 5 to about 10. Here, the ratio of aluminum content (e.g., amount) to zirconium content (e.g., amount) may be a molar ratio.

[0076] It should be understood that the aluminum and zirconium raw materials according to one or more embodiments can serve as raw materials for dopants, while also acting as grain growth promoters, and by adding them respectively in the above-mentioned content (e.g., amount) range, single particles in the form of core particles in an optimal or appropriate state can be obtained.

[0077] The aluminum raw material may be alumina, such as Al2O3. In one or more embodiments, the zirconium raw material may be zirconium oxide, such as ZrO2.

[0078] The method for preparing positive electrode active materials according to one or more embodiments can be performed at lower temperatures (e.g., a first heat treatment) than commonly used or generally available single-particle synthesis methods. For example, even with heat treatment at relatively low temperatures, it is possible to obtain desirable single particles as the core particles of the positive electrode active material. Accordingly, the process can be simplified, economic efficiency improved, particle aggregation problems reduced, and yield and processability improved.

[0079] The first heat treatment may be carried out at a temperature less than or equal to about 900°C, less than or equal to about 890°C, less than or equal to about 850°C, or less than or equal to about 810°C (e.g., about 700°C to about 900°C, about 710°C to about 890°C, about 730°C to about 850°C, or about 750°C to about 810°C).

[0080] The first heat treatment can be carried out in an oxidizing gas atmosphere, and air or oxygen can be used as the oxidizing gas. For example, the second heat treatment can be carried out in an air atmosphere or in an atmosphere containing more than or equal to about 50 vol% (e.g., about 60 vol% to about 99 vol%, about 70 vol% to about 98 vol%, or about 90 vol% to about 95 vol%) of oxygen.

[0081] The first heat treatment can be carried out within the above temperature range, for example, for about 4 to about 20 hours, about 5 to about 15 hours, or about 6 to about 12 hours.

[0082] In the method for preparing the positive electrode active material according to one or more embodiments, during the process of mixing nickel-based composite hydroxide, lithium raw material, aluminum raw material, and zirconium raw material and performing a first heat treatment, an alkaline grain growth promoter or co-solvent may not be added. Accordingly, an increase in impedance (e.g., resistance) due to residues (e.g., undesirable impurities) after heat treatment can be prevented or reduced, the cycle life characteristics of the rechargeable lithium battery can be improved or enhanced, and the process and economy can be improved or enhanced without the need for a process to remove residues.

[0083] Through a first heat treatment, hollow secondary particles comprising layered lithium-nickel composite oxides can be obtained. At this time, by adding aluminum and zirconium raw materials, the multiple primary particles constituting the secondary particles can be sufficiently or appropriately grown into single crystals, and the secondary particles can have a hollow structure with internal pores, thus allowing them to be easily or appropriately pulverized in a subsequent pulverization step. In one or more embodiments, the secondary particles can have a hollow structure with internal pores, so they can be easily or appropriately pulverized in a subsequent pulverization step.

[0084] In one or more embodiments, the secondary particles may be large particles, and by using precursors of these large particles for the processes further described herein, the resulting filter cake may have lower hardness, making it easier to pulverize and improving or increasing hourly output. For example, the average particle size (D) of the secondary particles... 50 The size of the secondary particles can be approximately 10 μm to approximately 20 μm, for example, approximately 10 μm to approximately 18 μm or approximately 12 μm to approximately 16 μm. The average particle size (D) of the secondary particles... 50 It can be measured using SEM images.

[0085] The average particle size (D) of the multiple primary particles that make up the secondary particles 50 The diameter (D) of the primary particles can range from approximately 1 μm to approximately 4 μm, for example, approximately 1.5 μm to approximately 4 μm, approximately 2 μm to approximately 4 μm, or approximately 2.5 μm to approximately 3.8 μm. 50 The surface of the secondary particles can be measured using SEM images.

[0086] The average size of the internal pores within the secondary particles can be approximately 1 μm to approximately 9 μm, for example, approximately 2 μm to approximately 8 μm or approximately 3 μm to approximately 7 μm. The average size of the pores within the secondary particles can be measured from an SEM image of a cross-section of the secondary particles and can refer to the length of the major axis of the pores.

[0087] The obtained layered lithium-nickel composite oxide can be represented by chemical formula 11, which will be described further in this paper.

[0088] Then, (iii) the obtained secondary particles can be pulverized. In process (iii) above, pulverizing secondary particles refers to breaking the secondary particles, and can be understood as a process in which multiple primary particles forming secondary particles are separated from each other to become single particles. Through the pulverization process, core particles of the positive electrode active material in the form of single particles can be obtained.

[0089] According to the preparation method described above, if (for example, when) nickel-based composite hydroxide and lithium raw materials are mixed and heat-treated, aluminum and zirconium raw materials can be added together and heat-treated, so that multiple primary particles can be single particles with sufficient or appropriate size at a relatively low temperature of 900°C or lower. Through the above process, secondary particles in which multiple primary particles are aggregated can be obtained, and by pulverizing them, the desired or appropriate single particle form of the core particle as a positive electrode active material can be obtained.

[0090] According to the preparation method described above, by using a nickel-based composite hydroxide with internally provided micropores as a precursor, layered lithium-nickel composite oxides in the form of hollow secondary particles can be obtained after heat treatment. Correspondingly, single particles can be prepared by easily or appropriately pulverizing the secondary particles. In one or more embodiments, if (e.g., when) a nickel-based composite hydroxide and a lithium feedstock are mixed and heat-treated, aluminum and zirconium feedstocks can be added together and heat-treated, such that multiple primary particles can be transformed into single particles of sufficient or appropriate size at a relatively low temperature of 900°C or lower. Through the above process, secondary particles in which multiple primary particles are aggregated can be obtained, and by pulverizing them, single particles of the desired or appropriate shape as core particles for positive electrode active materials can be obtained.

[0091] The grinding can be carried out using a jet mill and / or an air classifier (ACM) device. If, for example, grinding is performed using a jet mill, the air pressure can be suitably or appropriately adjusted (e.g., adjusted to about 2 bar to about 8 bar or about 4 bar to about 6 bar) so that the bulk density of the ground product can be about 0.2 g / cm³. 3 ~0.5g / cm 3 The above pulverization process can be carried out for, for example, about 10 minutes to about 120 minutes, such as about 10 minutes to about 80 minutes, about 10 minutes to about 60 minutes, or about 20 minutes to about 50 minutes.

[0092] Subsequently, (iv) the pulverized result (e.g., pulverized secondary particles), the cobalt coating material, and the zirconium coating material may be added to and mixed in an aqueous (e.g., water-soluble) solvent, followed by a second heat treatment to obtain the positive electrode active material. The cobalt coating material may be a hydroxide, oxide, nitrate, sulfate, carbonate, or a combination thereof comprising cobalt. The zirconium coating material may be a hydroxide, oxide, nitrate, sulfate, carbonate, or a combination thereof comprising zirconium.

[0093] As an example, an aqueous (e.g., water-soluble) solvent may be a commonly used or commonly available solvent, and may include, for example, water, distilled water, alcohol solvents and / or combinations thereof.

[0094] For example, the second heat treatment can be carried out in an oxidizing gas atmosphere, and air or oxygen can be used as the oxidizing gas. For example, the second heat treatment can be carried out in an air atmosphere or an atmosphere containing more than or equal to about 50 vol%, about 60 vol% to about 99 vol%, about 70 vol% to about 98 vol%, or about 90 vol% to about 95 vol%.

[0095] In one or more embodiments, the second heat treatment may be performed at a temperature of about 500°C to about 900°C, about 600°C to about 800°C, or about 650°C to about 750°C. The second heat treatment may be performed in an oxidizing gas atmosphere for, for example, about 10 hours to about 20 hours, about 14 hours to about 19 hours, or about 15 hours to about 18 hours. If (for example, when) these second heat treatment conditions are met, a positive electrode active material having better or more suitable surface stability and improved or enhanced cycle life characteristics can be effectively or appropriately prepared.

[0096] In a method for preparing a positive electrode active material according to one or more embodiments, based on 100 mol% of the total metal of a nickel-based composite hydroxide, aluminum from an aluminum raw material, zirconium from a zirconium raw material, cobalt from a cobalt coating raw material, and zirconium from a zirconium coating raw material, the cobalt content (e.g., amount) of the cobalt coating raw material can be adjusted to about 0.5 mol% to about 5 mol%, for example, about 0.7 mol% to about 4 mol%, about 0.8 mol% to about 3 mol%, or about 1 mol% to about 2 mol%. Within the above ranges, the coating can effectively or appropriately improve or enhance cycle life characteristics without acting as an impedance (e.g., resistance) and without reducing capacity (e.g., capacitance).

[0097] In a method for preparing a positive electrode active material according to one or more embodiments, based on 100 mol% of total metals of a nickel-based composite hydroxide, aluminum from an aluminum raw material, zirconium from a zirconium raw material, cobalt from a cobalt coating raw material, and zirconium from a zirconium coating raw material, the zirconium content (e.g., amount) of the zirconium coating raw material can be adjusted to about 0.1 mol% to about 3 mol%, for example, about 0.2 mol% to about 2 mol% or about 0.3 mol% to about 1 mol%. Within the above range, cycle life characteristics can be effectively or appropriately improved or enhanced, without the coating acting as an impedance (e.g., resistance).

[0098] In one or more embodiments, the positive electrode active material may include: a core particle, comprising a layered lithium-nickel composite oxide and in the form of a single particle; and a coating provided on the surface of the core particle and comprising cobalt and zirconium.

[0099] It can be synthesized even through relatively low-temperature heat treatment, and in order to achieve excellent or appropriate cycle life characteristics, the positive electrode active material may include layered lithium nickel composite oxides as core particles.

[0100] For example, the layered lithium-nickel composite oxide of the core particles can be a high-nickel oxide, with a nickel content (e.g., amount) based on 100 mol% of total metals other than lithium greater than or equal to about 60 mol%. Based on 100 mol% of total metals other than lithium, the nickel content (e.g., amount) of the layered lithium-nickel composite oxide can be, for example, greater than or equal to about 65 mol%, greater than or equal to about 70 mol%, greater than or equal to about 75 mol%, greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, greater than or equal to about 94 mol% and less than or equal to about 99 mol%, or less than or equal to about 98 mol%.

[0101] In one or more embodiments, in addition to nickel, the layered lithium-nickel composite oxide core particles may also include aluminum and / or zirconium as a (or type of) dopant in a defined or specific amount. In the layered lithium-nickel composite oxide, based on 100 mol% of total metals excluding lithium, the aluminum content (e.g., amount) may be from about 0.8 mol% to about 1.5 mol%, for example, from about 0.8 mol% to about 1.4 mol%, from about 0.8 mol% to about 1.3 mol%, or from about 0.9 mol% to about 1.2 mol%. In the layered lithium-nickel composite oxide, based on 100 mol% of total metals excluding lithium, the zirconium content (e.g., amount) may be from about 0.1 mol% to about 0.3 mol%, for example, from about 0.1 mol% to about 0.2 mol%.

[0102] As an example, the molar ratio (Al / Zr) of aluminum content (e.g., amount) to zirconium content (e.g., amount) in the layered lithium-nickel composite oxide of the core particles can be greater than or equal to about 5, for example, about 5 to about 15 or about 5 to about 10. Here, the ratio of aluminum content (e.g., amount) to zirconium content (e.g., amount) can be a molar ratio. If (e.g., when) the ratio of aluminum content (e.g., amount) to zirconium content (e.g., amount) meets or is within the above range, it can be synthesized at a relatively low firing temperature, without the need for, for example, basic grain growth additives during the synthesis process, and can have long cycle life characteristics due to high structural stability.

[0103] In one or more embodiments, the layered lithium-nickel composite oxide may be represented by chemical formula 11.

[0104] Chemical Formula 11

[0105] Li a11 Ni x11 M 1 y11 Al z11 Zr w11 O 2-b11 X b11

[0106] In chemical formula 11, 0.9 ≤ a11 ≤ 1.2, 0.6 ≤ x11 ≤ 0.991, 0 ≤ y11 ≤ 0.391, 0.008 ≤ z11 ≤ 0.015, 0.001 ≤ w11 ≤ 0.003, 0.9 ≤ x11 + y11 + z11 + w11 ≤ 1.1, and 0 ≤ b11 ≤ 0.1, M 1 X may be one or more elements selected from B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zn, and X may be one or more elements selected from fluorine (F), phosphorus (P), and sulfur (S).

[0107] In chemical formula 11, 0.9 ≤ a11 ≤ 1.1, 0.9 ≤ a11 ≤ 1.05, or 0.9 ≤ a11 ≤ 1. In one or more embodiments, 0.7 ≤ x11 ≤ 0.991 and 0 ≤ y11 ≤ 0.291, or 0.8 ≤ x11 ≤ 0.991 and 0 ≤ y11 ≤ 0.191, or 0.9 ≤ x11 ≤ 0.991 and 0 ≤ y11 ≤ 0.091. z11, representing the Al content (e.g., amount), can be, for example, 0.008 ≤ z11 ≤ 0.014, 0.008 ≤ z11 ≤ 0.013, or 0.009 ≤ z11 ≤ 0.012. w11, representing the Zr content (e.g., amount), can be, for example, 0.001 ≤ w11 ≤ 0.002.

[0108] In Chemical Formula 11, 5 ≤ z11 / w11 can be satisfied. For example, 5 ≤ z11 / w11 ≤ 15 or 5 ≤ z11 / w11 ≤ 10.

[0109] For example, the layered lithium nickel-based composite oxide can be represented by Chemical Formula 12.

[0110] Chemical Formula 12

[0111] Li a12 Ni x12 Co v12 M 2 y12 Al z12 Zr w12 O 2-b12 X b12

[0112] In Chemical Formula 12, 0.9 ≤ a12 ≤ 1.2, 0.6 ≤ x12 < 0.991, 0 < v12 ≤ 0.391, 0 ≤ y12 ≤ 0.391, 0.008 ≤ z12 ≤ 0.015, 0.001 ≤ w12 ≤ 0.003, 0.9 ≤ x12 + v12 + y12 + z12 + w12 ≤ 1.1, and 0 ≤ b12 ≤ 0.1, M 2 can be one or more elements selected from B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zn, and X can be one or more elements selected from F, P, and S.

[0113] In Chemical Formula 2, 5 ≤ z12 / w12 can be satisfied. For example, 5 ≤ z12 / w12 ≤ 15 or 5 ≤ z12 / w12 ≤ 10. [[ID=%]]

[0114] To ensure structural stability and achieve the long cycle life characteristics of the positive electrode active material, the core particles can be in the form of single particles. Here, the single particle can exist alone without grain boundaries inside the particle, can be composed of one particle, and can be a single particle, an integral structure, a one-piece structure, or non-aggregated particles in which the particles do not aggregate with each other morphologically and exist as independent phases, and can be represented as a single particle (e.g., an integral particle or a single crystal grain), for example, a single crystal. The single particle can exist alone, or the single particles can aggregate together. For example, two to nine single particles can aggregate and contact each other.

[0115] In one or more embodiments, the single particles can exist alone, or five or fewer single particles can be attached (or aggregated) to each other.

[0116] As an example, the average particle size (D 50The particle size can range from about 1 μm to about 10 μm, for example, about 1 μm to about 8 μm, about 1 μm to about 4 μm, about 1.5 μm to about 4 μm, about 2 μm to about 4 μm, or about 2.5 μm to about 3.8 μm. Individual particles meeting these particle size ranges can be structurally stable, increasing the energy density of the positive electrode and improving or enhancing the long cycle life characteristics of rechargeable lithium batteries. Here, the average particle size can be obtained by randomly measuring the particle size (e.g., diameter, major axis, or major axis length) of 20 particles in a scanning electron microscope image to obtain the particle size distribution, and the size of particles representing 50% of the cumulative volume can be calculated.

[0117] To ensure excellent or appropriate cycle life characteristics by improving or enhancing the surface stability and ionic conductivity of the positive electrode active material, the positive electrode active material may include a coating.

[0118] The positive electrode active material may include a coating provided on the surface of the core particle and comprising cobalt and zirconium. By including a coating comprising cobalt and zirconium, the positive electrode active material can improve or enhance the structural stability of the core particle and effectively or appropriately suppress or reduce side reactions with the electrolyte (e.g., suppress or reduce the degree or occurrence of side reactions with the electrolyte), thereby improving or enhancing cycle life characteristics.

[0119] In one or more embodiments, the coating may be provided continuously (e.g., substantially continuously) on the surface of the core particle, or the coating may be provided in a discontinuous (e.g., substantially discontinuous) island shape.

[0120] As an example, due to diffusion and other processes during the preparation process, the coating may further include nickel, manganese, etc., which flow in from the core, in addition to cobalt and zirconium. However, the coating may be a layer in which cobalt and zirconium are the main or dominant components.

[0121] As an example, the coating thickness can be from about 5 nm to about 500 nm, for example, from about 10 nm to about 300 nm or from about 50 nm to about 200 nm. Within the above range, the coating can achieve the effect of improving or increasing cycle life characteristics without acting as an impedance (e.g., resistance) and without reducing capacity (e.g., capacitance).

[0122] In one or more embodiments, based on 100 mol% of total metals other than lithium in the positive electrode active material, the cobalt content (e.g., amount) of the coating may be from about 0.5 mol% to about 5 mol%. Within the above range, the coating can effectively improve or enhance cycle life characteristics without acting as an impedance (e.g., resistance) and without reducing capacity (e.g., capacitance).

[0123] As an example, based on 100 mol% of total metals other than lithium in the positive electrode active material, the zirconium content (e.g., amount) of the coating can be from about 0.1 mol% to about 3 mol%. Within the above range, the coating may not act as an impedance (e.g., resistance) and may improve or enhance cycle life characteristics without reducing capacity (e.g., capacitance).

[0124] In one or more embodiments, the cobalt content (e.g., amount) of the coating is... co ) and the zirconium content (e.g., amount) of the coating (W) zr molar ratio (W) co / W zr The concentration can be from about 1.1 to about 10, for example, from about 2 to about 9 or from about 5 to about 8. Within the above range, the effects of adding cobalt and zirconium to the coating can be coordinated (e.g., synergistic).

[0125] Rechargeable lithium batteries

[0126] In one or more embodiments, the rechargeable lithium battery may include a positive electrode, a negative electrode, and / or an electrolyte, and the positive electrode may include a positive electrode active material prepared by a method according to one or more embodiments.

[0127] In one or more embodiments, the positive electrode may include: a positive electrode current collector; and a positive electrode active material layer on the positive electrode current collector and comprising the positive electrode active material prepared by a preparation method according to one or more embodiments.

[0128] In one or more embodiments, a rechargeable lithium battery may include a positive electrode, a negative electrode, a separator between the positive and negative electrodes, and / or an electrolyte.

[0129] Rechargeable lithium batteries can be classified according to their shape as cylindrical batteries, prismatic batteries, pouch batteries, coin batteries, etc. Figures 1-4 Each of the above is a schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments, wherein... Figure 1 It is a cylindrical battery. Figure 2 It is a prismatic battery, and Figure 3 and Figure 4 Each is a pouch-shaped battery. (Reference) Figures 1-4 The rechargeable lithium battery 100 may include an electrode assembly 40 (having a separator 30 between a positive electrode 10 and a negative electrode 20) and a housing 50 (in which the electrode assembly 40 is housed). The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte. The rechargeable lithium battery 100 may include a sealing member 60 for sealing the housing 50, such as... Figure 1 As shown. In Figure 2In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12, a negative electrode lead connector 21, and / or a negative electrode terminal 22. For example... Figure 3 and Figure 4 As shown, the rechargeable lithium battery 100 may include electrode terminals 70, such as positive electrode terminal 71 and negative electrode terminal 72, which serve as electrical paths for guiding current generated in the electrode assembly 40 to the outside.

[0130] positive electrode

[0131] The positive electrode may include a positive electrode current collector and a layer of positive electrode active material on the positive electrode current collector. In addition to the positive electrode active material according to one or more embodiments, the positive electrode active material layer may further include a binder, a conductive material, and / or a combination thereof.

[0132] Positive electrode active material

[0133] The positive electrode active material may be a compound capable of reversibly inserting and deintercalating lithium (e.g., a lithium-intercalating compound), and may utilize a positive electrode active material according to one or more embodiments related to the method of preparing the positive electrode active material.

[0134] adhesive

[0135] Binders can improve or enhance the adhesion properties between positive electrode active material particles and between positive electrode active material particles and positive electrode current collector. Examples of binders may include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resins, (meth)acrylate resins, polyester resins and / or nylon.

[0136] conductive materials

[0137] Conductive materials may be included to provide electrode conductivity, and any suitable conductive material may be used as a conductive material unless it causes a chemical change (e.g., an undesirable chemical change in a rechargeable lithium battery). Examples of conductive (e.g., electrically conductive) materials may include: carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, carbon nanotubes, etc.); metallic materials including metal powders and / or metal fibers of copper, nickel, aluminum, silver, etc.; conductive (e.g., electrically conductive) polymers (such as polyphenylene and / or derivatives thereof); and / or mixtures thereof.

[0138] Based on a 100wt% positive electrode active material layer, the respective contents (e.g., amounts) of the binder and conductive material can be from about 0.5wt% to about 5wt%.

[0139] The positive electrode current collector may include, but is not limited to, aluminum (Al) foil.

[0140] negative electrode

[0141] The negative electrode may include a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector, wherein the negative electrode active material layer may include a negative electrode active material and may further include a binder, a conductive material and / or a combination thereof.

[0142] Negative electrode active material

[0143] The negative electrode active material may include materials that can reversibly insert / deintercalate lithium ions, lithium metal, lithium metal alloys, materials that can be doped / dedoped with lithium, or transition metal oxides.

[0144] Materials capable of reversibly inserting / deintercalating lithium ions can include, for example, crystalline carbon, amorphous (e.g., non-crystalline) carbon, and / or combinations thereof as carbon-based negative electrode active materials. Crystalline carbon can be amorphous (e.g., irregular) and / or sheet-like (e.g., substantially sheet-like), flake-like (e.g., substantially flake-like), spherical (e.g., substantially spherical), and / or fibrous (e.g., substantially fibrous) natural graphite and / or artificial graphite. Amorphous (e.g., non-crystalline) carbon can be soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0145] Lithium metal alloys may include alloys of lithium and metals selected from sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), silicon (Si), antimony (Sb), lead (Pb), indium (In), zinc (Zn), barium (Ba), radium (Ra), germanium (Ge), aluminum (Al), and tin (Sn).

[0146] Materials capable of doping / dedoping lithium can be Si-based and / or Sn-based negative electrode active materials. Si-based negative electrode active materials may include silicon, silicon-carbon composites, and SiO₂. x(0 < x ≤ 2), Si-Q alloy (where Q can be 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, such as, for example, Mg, Ca, Sr, Ba, Ra, scandium (Sc), yttrium (Y), Ti, zirconium (Zr), hafnium (Hf), rutherfordium (Rf), V, Nb, tantalum (Ta), dubnium (Db), Cr, Mo, W, seaborgium (Sg), technetium (Tc), rhenium (Re), bohrium (Bh), Fe, Pb, ruthenium (Ru), osmium (Os), hassium (Hs), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), Cu, silver (Ag), gold (Au), Zn, cadmium (Cd), B, Al, gallium (Ga), Sn, In, thallium (Tl), Ge, P, arsenic (As), Sb, bismuth (Bi), S, selenium (Se), tellurium (Te), polonium (Po), and combinations thereof) or combinations thereof. The Sn-based negative electrode active material can be Sn, SnO k (0 < k ≤ 2) (for example, SnO2) 、 Sn alloy or combinations thereof.

[0147] The silicon-carbon composite can be a composite of silicon and amorphous (e.g., non-crystalline) carbon. The average particle size (D 50 ) 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 / or amorphous (e.g., non-crystalline) carbon coated on the surface of the silicon particles. For example, it can include secondary particles (cores) in which silicon primary particles are concentrated and / or an amorphous (e.g., non-crystalline) carbon coating (shells) on the surface of the secondary particles. Amorphous (e.g., non-crystalline) carbon can also be provided between the silicon primary particles. For example, the silicon primary particles can be coated with amorphous (e.g., non-crystalline) carbon. The secondary particles can be provided (e.g., dispersed) in an amorphous (e.g., non-crystalline) carbon matrix.

[0148] The silicon-carbon composite can further include crystalline carbon. For example, the silicon-carbon composite can contain a core including crystalline carbon and / or silicon particles and / or an amorphous (e.g., non-crystalline) carbon coating on the surface of the core. The crystalline carbon can be artificial graphite, natural graphite, or combinations thereof. The amorphous (e.g., non-crystalline) carbon can include soft carbon, hard carbon, mesophase pitch carbonization products, and / or calcined coke.

[0149] If (e.g., when) the silicon-carbon composite includes silicon and amorphous (e.g., non-crystalline) carbon, the content (e.g., amount) of silicon can be about 10 wt% to about 50 wt%, and based on 100 wt% of the silicon-carbon composite, the content (e.g., amount) of amorphous (e.g., non-crystalline) carbon can be about 50 wt% to about 90 wt%. In one or more embodiments, if (e.g., when) the silicon-carbon composite includes silicon, amorphous (e.g., non-crystalline) carbon, and crystalline carbon, then based on 100 wt% of the silicon-carbon composite, the content (e.g., amount) of silicon 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 (e.g., non-crystalline) carbon can be about 20 wt% to about 40 wt%.

[0150] In one or more embodiments, the thickness of the amorphous (e.g., non-crystalline) carbon coating can be about 5 nm to about 100 nm. The average particle diameter (D 50 ) of the silicon particles (e.g., primary particles) can be about 10 nm to about 1 μm or about 10 nm to about 200 nm. The silicon particles can exist as elemental silicon, in the form of a silicon alloy, or in the form of an oxide of silicon. The oxide form of silicon can be represented by SiO x (0 < x ≤ 2). At this time, the atomic content (e.g., amount) ratio Si:O indicating the degree of oxidation can be about 99:1 to about 33:67. If (e.g., when) no other definition is provided, the average particle diameter (D 50 ) as used herein indicates the diameter of the particles with a cumulative volume of about 50% by volume in the particle size distribution.

[0151] The Si-based negative electrode active material and / or the Sn-based negative electrode active material can be mixed with the carbon-based negative electrode active material. If (e.g., 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.

[0152] Binder

[0153] The binder can be used to bond the negative electrode active material particles well or properly to each other and / or to bond the negative electrode active material well or properly to the negative electrode current collector. The binder can be a non-aqueous (e.g., water-insoluble) binder, an aqueous (e.g., water-soluble) binder, a dry binder, or a combination thereof.

[0154] The non-aqueous (e.g., water-insoluble) binder can include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, and / or a combination thereof.

[0155] Waterborne (e.g., water-soluble) adhesives may include styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, 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.

[0156] If (for example, when) an aqueous (e.g., water-soluble) binder is used as a binder in the negative electrode active material layer, it may further include a cellulose-based compound capable of imparting viscosity. As a cellulose-based compound, one or more selected from carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts may be mixed and used. The alkali metal may be Na, K, or Li.

[0157] Dry binders can be polymeric materials capable of being fibrous or manufactured into fibers, and can be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0158] conductive materials

[0159] Conductive materials may be included to provide electrode conductivity, and any suitable conductive material may be used as a conductive material unless it causes a chemical change (e.g., an undesirable chemical change in a rechargeable lithium battery). Examples of conductive (e.g., electrically conductive) materials may include: carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, carbon nanotubes, etc.); metallic materials including metal powders and / or metal fibers of copper, nickel, aluminum, silver, etc.; conductive (e.g., electrically conductive) polymers (such as polyphenylene and / or derivatives thereof); and / or mixtures thereof.

[0160] Based on a 100 wt% negative electrode active material layer, the amount of negative electrode active material can be from about 95 wt% to about 99.5 wt%, and based on the 100 wt% negative electrode active material layer, the content (e.g., amount) of binder can be from 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% negative electrode active material, about 0.5 wt% to about 5 wt% binder, and / or about 0.5 wt% to about 5 wt% conductive (e.g., electrically conductive) material.

[0161] 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), and / or alloys thereof, and may be in the form of foil, sheet, or 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.

[0162] electrolyte

[0163] For example, the electrolyte for a rechargeable lithium battery may be an electrolyte that may include non-aqueous (e.g., water-insoluble) organic solvents and / or lithium salts.

[0164] Non-aqueous (e.g., water-insoluble) organic solvents can be used as media for transporting ions that participate in the electrochemical reactions of rechargeable lithium batteries. Non-aqueous (e.g., water-insoluble) organic solvents may include carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, or combinations thereof.

[0165] 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), and butyl carbonate (BC), etc. Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolactone, mevalonolactone, valproic acid lactone, 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. Ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., while aprotic solvents may include nitriles (such as R-CN (where R can be a C2-C20 straight-chain, branched, or cyclic hydrocarbon group, and may include double bonds, aromatic rings, or ether bonds, etc.)); amides (such as dimethylformamide, etc.); dioxolane (such as 1,3-dioxolane, 1,4-dioxolane, etc.); sulfolane, etc.

[0166] Non-aqueous (e.g., water-insoluble) organic solvents can be used alone or in mixtures of two or more kinds or types, and if (e.g., when) two or more kinds or types are used in mixtures, the mixing ratio can be suitably or appropriately adjusted according to desired or appropriate battery performance, which is generally available to those skilled in the art.

[0167] If (for example, when) a carbonate solvent is used, cyclic carbonates and chain carbonates can be mixed and used, and cyclic carbonates and chain carbonates can be mixed in a volume ratio of about 1:1 to about 1:9.

[0168] Non-aqueous (e.g., water-insoluble) organic solvents may further include aromatic hydrocarbon organic solvents. For example, carbonate solvents and aromatic hydrocarbon organic solvents may be mixed and used in a volume ratio of about 1:1 to about 30:1.

[0169] The electrolyte may further include ethylene ethyl carbonate, vinylene carbonate and / or ethylene carbonate compounds to improve or enhance the cycle life of the rechargeable lithium battery.

[0170] Examples of ethylene carbonate compounds may include fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, and / or cyanoethylene carbonate.

[0171] Lithium salts dissolved in non-aqueous organic solvents can supply or provide lithium ions in rechargeable lithium batteries, ensuring basic operation and improving or enhancing lithium ion transport between the positive and negative electrodes. Examples of lithium salts may include those 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+ At least one of 1SO2 (where x and y can be integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0172] The concentration of lithium salt can be in the range of about 0.1 M to about 2.0 M. If (for example, when) the concentration of lithium salt is within the above range, the electrolyte can have suitable or appropriate ionic conductivity and viscosity, thus achieving excellent or appropriate performance, and lithium ions can migrate effectively or appropriately.

[0173] diaphragm

[0174] Depending on the type or variety of rechargeable lithium-ion battery, a separator may be present between the positive and negative electrodes. The separator may include polyethylene separators, polypropylene separators, polyvinylidene fluoride separators, and / or multilayer films of two or more layers (such as polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, polypropylene / polyethylene / polypropylene three-layer separators, etc.).

[0175] The diaphragm may include a porous substrate and a coating on one or both surfaces (e.g., two opposite surfaces) of the porous substrate, the coating comprising an organic material, an inorganic material, or a combination thereof.

[0176] The porous substrate may be a polymer film selected from any one of the following polymers or copolymers or mixtures thereof: polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber, and polytetrafluoroethylene (Teflon). TM ).

[0177] 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.

[0178] Organic materials may include (meth)acrylic acid copolymers, which include: a first structural unit derived from (meth)acrylamide; and / or a second structural unit comprising at least one structural unit selected from structural units derived from (meth)acrylic acid or (meth)acrylates and structural units derived from (meth)acrylamidosulfonic acid or salts thereof.

[0179] Inorganic materials may include, but are not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof. The average particle size (D) of the inorganic particles... 50 The range can be approximately 1 nm to approximately 2000 nm, for example, approximately 100 nm to approximately 1000 nm or approximately 100 nm to approximately 700 nm.

[0180] Organic and inorganic materials can be mixed in a coating, or they can exist in the form of a coating that includes organic materials and a coating that includes inorganic materials stacked together.

[0181] The thickness of the coating can be from about 0.5 μm to about 20 μm, for example, from about 1 μm to about 10 μm or from about 1 μm to about 5 μm.

[0182] Embodiments and comparative examples of this disclosure are described below. However, the following examples are merely examples of this disclosure, and the implementation of this disclosure is not limited to the following examples.

[0183] Example 1

[0184] 1. Preparation of positive electrode active material

[0185] (1) Preparation of nickel-based complex hydroxides

[0186] Nickel-based complex hydroxides were prepared by the following co-precipitation method. A mixed solution of metal raw materials was prepared by dissolving nickel sulfate, cobalt sulfate, and manganese sulfate in distilled water as a solvent, such that the molar ratio Ni:Co:Mn = 95:4:1. A dilute ammonia solution (NH4OH) was prepared as a complexing agent, and sodium hydroxide (NaOH) was prepared as a pH adjuster. The concentration of ammonia was 10 wt%, and the concentration of sodium hydroxide was 20 wt%. The prepared mixed solution of metal raw materials, the dilute ammonia solution (NH4OH), and the sodium hydroxide were then separately injected into a reactor.

[0187] After setting the pH in the reactor to 11.75, the resulting mixture was stirred for 10 hours (first step) and then stirred for 22 hours after the pH was lowered to 11.55 (second step), thereby creating a synthesis rate difference between the inside and outside of the particles to synthesize a slurry solution of nickel-based composite hydroxides.

[0188] The slurry solution obtained from the filtration reactor was rinsed with high-purity distilled water and dried in a hot air oven at 180°C for 24 hours to obtain nickel-based composite hydroxide (Ni 0.95 Co 0.04 Mn 0.01 (OH)2). The obtained nickel-based composite hydroxides are in the form of secondary particles provided by the aggregation of multiple primary particles, wherein the average particle size (D) of the secondary particles, when measured using SEM images, is... 50 The value is approximately 13.2 μm.

[0189] (2) Preparation of positive electrode active material

[0190] The obtained nickel-based composite hydroxide was mixed with anhydrous lithium hydroxide, Al₂O₃, and ZrO₂. In this study, the anhydrous lithium hydroxide was mixed such that the molar ratio of lithium to the total metal of the nickel-based composite hydroxide, Al of Al₂O₃, and Zr of ZrO₂ was 1.05 relative to 1 mole of the total metal of the nickel-based composite hydroxide. Furthermore, Al₂O₃ was added such that, based on 100 mol% of the total metal of the nickel-based composite hydroxide, Al of Al₂O₃, and Zr of ZrO₂, the Al of Al₂O₃ was 1 mol%, and ZrO₂ was added such that, based on 100 mol% of the total metal of the nickel-based composite hydroxide, Al of Al₂O₃, and Zr of ZrO₂, the Zr of ZrO₂ was 0.1 mol%.

[0191] The resulting mixture was heat-treated at 810 °C for 8 hours under an atmosphere containing 90% by volume oxygen. The product obtained from the first heat treatment exhibited Li 1.00 Ni0.939 Co 0.04 Mn 0.01 Al 0.01 Zr 0.001 Composed of O2, and when detected using SEM images, it was confirmed to have a hollow secondary particle shape. Figure 5 This is a SEM image of a cross-section of a secondary particle.

[0192] When measured using SEM images, the secondary particles have an average particle size of approximately 13.5 μm (D). 50 The primary particles that form secondary particles have an average particle size of approximately 2.7 μm (D). 50 Furthermore, the secondary particles have an internal pore size of approximately 4 μm.

[0193] The product obtained from the first heat treatment was pulverized for 20 minutes using a jet mill at an air pressure of about 5 bar, and when inspected using SEM images, it was confirmed that the pulverized product was a single particle with an average particle size of about 2.7 μm.

[0194] The pulverized product was washed with distilled water solvent, and then coated with cobalt and zirconium by adding Co(OH)₂ and Zr(OH)₂ and mixing them. Subsequently, after removing the distilled water solvent, the coated product was dried at 190°C and subjected to a second heat treatment at 720°C for 16 hours in an atmosphere containing 90% by volume oxygen to obtain the positive electrode active material. In this paper, based on the total metal of 100 mol% nickel-based composite hydroxide, aluminum from aluminum raw material, zirconium from zirconium raw material, cobalt from cobalt coating material, and zirconium from zirconium coating material, the cobalt content (e.g., amount) in the cobalt coating material was designed to be 2 mol%, and the zirconium content (e.g., amount) in the zirconium coating material was designed to be 0.3 mol%.

[0195] The results of scanning electron microscopy / energy-dispersive X-ray spectroscopy (SEM-EDS) analysis of the obtained positive electrode active material show that each Co and Zr-containing coating is sequentially provided on the surface of a single particle acting as the core particle. Furthermore, SEM images of the cross-section of the fabricated hollow secondary particles are shown below. Figure 5 middle.

[0196] 2. Manufacturing of rechargeable lithium battery cells

[0197] A positive electrode active material layer slurry was prepared by mixing 98.5 wt% of the manufactured positive electrode active material, 1.0 wt% of polyvinylidene fluoride binder, and 0.5 wt% of carbon nanotube conductive material. This positive electrode active material layer slurry was then coated onto an aluminum foil current collector to manufacture a positive electrode. The manufactured positive electrode contains positive electrode active material in the form of pulverized single particles.

[0198] An electrode assembly is manufactured using a positive electrode, a lithium counter electrode as a negative electrode, and a polytetrafluoroethylene separator provided between the two. After the electrode assembly is inserted into the battery casing, an electrolyte (prepared by mixing ethylene carbonate and dimethyl carbonate in a volume ratio of 3:7 and dissolving 1M LiPF6 in the mixed solvent) is injected into it to manufacture a rechargeable lithium battery cell using conventional methods.

[0199] Example 2

[0200] The positive electrode active material and rechargeable lithium battery cell were manufactured in essentially the same manner as in Example 1, except that the positive electrode active material was prepared by mixing ZrO2, such that the total metal based on 100 mol% nickel-based composite hydroxide, aluminum from aluminum raw material, zirconium from zirconium raw material, and Zr was 0.2 mol%, and then a first heat treatment was performed.

[0201] Comparative Example 1

[0202] The positive electrode active material and rechargeable lithium battery cell were manufactured in essentially the same manner as in Example 1, except that the positive electrode active material was prepared by performing a first heat treatment without mixing with ZrO2. In Comparative Example 1, the secondary particles were not pulverized by a spray milling process because the primary particles forming the secondary particles did not crystallize to a sufficient size under heat treatment at 810°C. In contrast, in Examples 1 and 2, when Al2O3 and ZrO2, each in a predetermined or set amount (e.g., quantity), were added to the first heat treatment under essentially the same temperature conditions for Al and Zr doping, grain growth of the nuclei was promoted, for example, the growth of primary particles or the crystallization of primary particles was promoted.

[0203] Comparative Example 2

[0204] The positive electrode active material and rechargeable lithium battery cell were manufactured in essentially the same manner as in Example 1, except that the positive electrode active material was prepared by mixing ZrO2, such that the total metal content based on 100 mol% nickel-based composite hydroxide, Al from Al2O3, and Zr from ZrO2, with Zr being 0.3 mol%, was then subjected to a first heat treatment. The Al / Zr molar ratio of Comparative Example 2 was 3.33, which is less than 5. It was confirmed that Comparative Example 2 exhibited excessive growth of primary particles during the process of forming the core particles, thus showing a decrease in initial charge and discharge capacity, charge and discharge efficiency, and cycle life characteristics.

[0205] Comparative Example 3

[0206] The positive electrode active material and rechargeable lithium battery cells were manufactured in essentially the same manner as in Example 1, except that instead of the two-step co-precipitation reaction of setting the pH in the reactor to 11.75 and stirring for 10 hours (first step) and then lowering the pH to 11.55 and stirring for 22 hours (second step), a first heat treatment was performed by increasing the pH conditions to 12.3 without changing the pH and stirring for 35 hours. As a result, an average particle size (D) was prepared. 50 The nickel-based complex hydroxide is in the form of secondary particles (small particles) of approximately 3 μm. In this paper, SEM images of the cross-sections of the secondary particles (small particles) are shown. Figure 6 middle.

[0207] Comparative Example 4

[0208] The positive electrode active material and rechargeable lithium battery cells were manufactured in essentially the same manner as in Example 1, except that instead of the two-step co-precipitation reaction of setting the pH in the reactor to 11.75 and stirring for 10 hours (first step) and then lowering the pH to 11.55 and stirring for 22 hours (second step), a first heat treatment was performed by increasing the pH conditions to 12.75 without changing the pH and stirring for 35 hours. As a result, an average particle size (D) was prepared. 50 The nickel-based complex hydroxide is in the form of secondary particles (large particles) of approximately 15 μm. In this paper, SEM images of the cross-sections of the secondary particles (large particles) are shown. Figure 7 middle.

[0209] Evaluation Example 1: Evaluation of Cycle Life Characteristics

[0210] The rechargeable lithium-ion battery cells according to Examples 1 and 2, and Comparative Examples 1 to 4, were initially charged and discharged at 0.2C to 4.45V at 25°C with a constant current of 0.2C, then charged to 0.05C with a constant voltage, and finally discharged to 3.0V at 0.2C. Subsequently, the battery cells were repeatedly charged and discharged 50 times at 1C within a voltage range of 3.0V to 4.45V at 45°C. The ratio of the discharge capacity to the initial discharge capacity for each cycle (i.e., the capacity retention rate) is shown in [Figure / Table / Issue]. Figure 8 middle.

[0211] refer to Figure 8 Comparative Examples 1 to 4 show that the capacity retention rate decreases as the cycle continues.

[0212] Conversely, it was confirmed that Examples 1 and 2 achieved excellent or appropriate cycle life characteristics.

[0213] Evaluation Example 2: Evaluation of Load Capacity and Top and Bottom Physical Characteristics

[0214] Loading tests were performed on Example 1, Comparative Examples 3 and 4 to evaluate the loading of the calcination inputs used to prepare the positive electrode active material, and the results are shown in Table 1. The loading test results of the positive electrode active material in Example 1 are shown in Table 1. Figure 9 In the figure, the loading results of the positive electrode active material of Comparative Example 3 are shown in the figure. Figure 10 The loading results of the positive electrode active material in Comparative Example 4 are shown in the figure. Figure 11 In addition, X-ray diffraction (XRD) analysis was performed on Example 1, Comparative Examples 3 and 4, and the results are also shown in Table 1.

[0215] Table 1

[0216]

[0217]

[0218] Refer to Table 1 and Figures 9-11 Example 1, which uses a large particle precursor in the preparation process, exhibits no separation between the top and bottom, as well as high loading and slight aggregation, resulting in a uniform positive electrode active material layer with minimal difference in X-ray diffraction (XRD) characteristics between the top and bottom.

[0219] In contrast, Comparative Example 3, which used a small particle precursor, showed separation at the top and bottom as well as large aggregation of individual particles, resulting in differences in XRD properties at the top and bottom.

[0220] In one or more embodiments, Comparative Example 4, which uses a large-particle precursor in the preparation process, exhibits no separation at the top and bottom and a small amount of aggregation, resulting in slight differences in the XRD characteristics at the top and bottom. However, compared to Example 1, it does not have an internal hollow space, which gives the primary particles more contact surface, making it difficult to crush the primary particles.

[0221] Evaluation Example 3: Evaluation of Charging and Discharging Efficiency

[0222] After initial charging and discharging as in Evaluation Example 1, the rechargeable lithium batteries of Example 1 and Comparative Examples 3 and 4 were subsequently charged and discharged 50 times at 1.0C in a voltage range of 3.0V to 4.45V at 45°C to measure the charging capacity and discharging capacity. The ratio of the latter to the former was then calculated as the charging and discharging efficiency, and the results are shown in Table 2.

[0223] Table 2

[0224] Comparative Example 3 Comparative Example 4 Example 1 Charging capacity (mAh / g) 235.1 235.8 235.8 Discharge capacity (mAh / g) 201.6 204.5 205.0 Charging and discharging efficiency (%) 85.8 86.7 86.9

[0225] Referring to Table 2, the use of positive electrode active material prepared from the large-particle hollow precursor according to Example 1 exhibits excellent or adequate charge and discharge capacity and the best or adequate charge and discharge efficiency.

[0226] On the other hand, the use of the positive electrode active material prepared by using the small-particle precursor according to Comparative Example 3 exhibited insufficient or unsuitable charge and discharge efficiency, as well as slightly lower charge and discharge capacity. In one or more embodiments, the use of the positive electrode active material prepared by using the large-particle precursor according to Comparative Example 4 exhibited the same level of charge capacity as Example 1, but the discharge capacity and charge and discharge efficiency were slightly lower than those of Example 1.

[0227] While the subject matter of this disclosure has been described in conjunction with exemplary embodiments that are now considered practical, it should be understood that this disclosure is not limited to the disclosed embodiments. In one or more embodiments, it is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the claims and their equivalents. Therefore, it will be understood that the above one or more embodiments are merely illustrative and not restrictive in all respects.

Claims

1. A method for preparing a positive electrode active material, comprising: A coprecipitation reaction is performed on a mixture of nickel precursor and metal precursor to obtain a nickel-based composite hydroxide with an average particle size of 10 μm to 20 μm. The coprecipitation reaction includes a first step at a pH range of pH 11 to pH 12 and a second step at a pH lower than that of the first step. The nickel-based composite hydroxide, anhydrous lithium hydroxide, aluminum raw material, and zirconium raw material are mixed and subjected to a first heat treatment to produce secondary particles comprising layered lithium-nickel composite oxides and composed of aggregates of multiple primary particles, wherein the secondary particles are hollow secondary particles with internal pores. The secondary particles are crushed, and The pulverized product, cobalt coating material, and zirconium coating material are added to an aqueous solvent and mixed, followed by a second heat treatment to obtain the positive electrode active material.

2. The method of claim 1, wherein: The metal precursor is B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn or a combination thereof.

3. The method of claim 1, wherein: Based on 100 mol% of the total metals of the nickel-based composite hydroxide, the aluminum of the aluminum raw material and the zirconium of the zirconium raw material, wherein the aluminum content of the aluminum raw material is 0.8 mol% to 1.5 mol% and the zirconium content of the zirconium raw material is 0.1 mol% to 0.3 mol%, and the molar ratio of the aluminum content to the zirconium content Al / Zr is greater than or equal to 5.

4. The method of claim 1, wherein: The nickel-based composite hydroxide is in an amorphous state.

5. The method of claim 1, wherein: The aluminum raw material is aluminum oxide, and The zirconium raw material is zirconium oxide.

6. The method of claim 1, wherein: Based on the total metals of the nickel-based composite hydroxide (100 mol%), the aluminum of the aluminum raw material, the zirconium of the zirconium raw material, the cobalt of the cobalt coating raw material, and the zirconium of the zirconium coating raw material, the cobalt content of the cobalt coating raw material is adjusted to 0.5 mol% to 5 mol%, and the zirconium content of the zirconium coating raw material is adjusted to 0.1 mol% to 3 mol%.

7. The method of claim 1, wherein: The first heat treatment is carried out in an oxidizing gas atmosphere at 700℃~900℃ for 4 hours~20 hours, and The second heat treatment is carried out in an oxidizing gas atmosphere at 500°C to 900°C for 10 to 20 hours.

8. The method of claim 1, wherein: The nickel-based complex hydroxide is represented by chemical formula 1: Chemical Formula 1 No x1 M 1 y1 (OH)2 In chemical formula 1, 0.6 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.4, 0.9 ≤ x1 + y1 ≤ 1.1, and M 1 It is one or more elements selected from B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zn.

9. The method of claim 1, wherein: In the nickel-based complex hydroxide, the nickel content is 80 mol% to 99 mol% based on 100 mol% of total metals excluding lithium.

10. The method of claim 1, wherein: The average particle size of the secondary particles is 10 μm to 20 μm. The average particle size of the plurality of primary particles constituting the secondary particles is 1 μm to 4 μm, and The average size of the pores inside the secondary particles is 1 μm to 9 μm.

11. The method of claim 1, wherein: The positive electrode active material includes: Core particles, including layered lithium-nickel composite oxides and existing as single particles; and A coating on the surface of the nuclear particle, wherein the coating comprises cobalt and zirconium.

12. The method of claim 11, wherein: Based on 100 mol% of total metals excluding lithium in the positive electrode active material, the cobalt content of the coating is 0.5 mol% to 5 mol%. Based on 100 mol% of total metals excluding lithium in the positive electrode active material, the zirconium content of the coating is 0.1 mol% to 3 mol%.

13. The method of claim 11, wherein: The layered lithium-nickel composite oxide of the core particle comprises aluminum and zirconium, and in the layered lithium-nickel composite oxide, based on 100 mol% of total metals other than lithium, it has a nickel content of greater than or equal to 60 mol%, an aluminum content of 0.8 mol% to 1.5 mol%, and a zirconium content of 0.1 mol% to 0.3 mol%, and the molar ratio of the aluminum content to the zirconium content, Al / Zr, is greater than or equal to 5.

14. The method of claim 11, wherein: The layered lithium-nickel composite oxide is represented by chemical formula 11: Chemical Formula 11 He a11 We x11 M 1 y11 To z11 Zr w11 Oh 2-b11 X b11 In chemical formula 11, 0.9 ≤ a11 ≤ 1.2, 0.6 ≤ x11 ≤ 0.991, 0 ≤ y11 ≤ 0.391, 0.008 ≤ z11 ≤ 0.015, 0.001 ≤ w11 ≤ 0.003, 0.9 ≤ x11 + y11 + z11 + w11 ≤ 1.1, and 0 ≤ b11 ≤ 0.1, M 1 X is one or more elements selected from B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zn, and X is one or more elements selected from F, P, and S.

15. The method of claim 11, wherein: The average particle size of the nuclear particles is 1 μm to 4 μm, and The thickness of the coating is 5nm to 500nm.

16. A rechargeable lithium battery, comprising: The positive electrode includes a positive electrode active material prepared by the method according to any one of claims 1 to 15; negative electrode; and Electrolyte.

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