Preparation method of positive electrode active material, positive electrode active material, and rechargeable lithium batteries

Abstract

An embodiment of the present invention provides a preparation method of a positive electrode active material, a positive electrode active material, and rechargeable lithium batteries. The method comprises the steps of: (1) preparing core particles containing a layered lithium nickel-manganese-based composite oxide and in the form of secondary particles, which are aggregates of a plurality of primary particles, single particles, or a combination thereof; (2) mixing at least one of an aluminum raw material or a boron raw material, the core particles, and cleaning water to clean the core particles; (3) obtaining a cleaned product by removing some of the cleaning water so that the content of the cleaning water is 1-10 wt% with respect to 100 wt% total of the core particles and the cleaning water; and (4) introducing the cleaned product and a tungsten raw material into a mixer and performing a heat treatment at 300-400°C.

Description

Method for manufacturing a positive electrode active material, positive electrode active material, and lithium secondary battery

[0001] This invention relates to a method for manufacturing a positive electrode active material, a positive electrode active material, and a lithium secondary battery.

[0002] Lithium-ion batteries, which offer high energy density and portability, are primarily used as the power source for mobile information terminals such as mobile phones, laptops, and smartphones. Recently, active research is being conducted to utilize high-energy-density lithium-ion batteries as power sources for driving or energy storage in hybrid and electric vehicles.

[0003] Various cathode active materials are being considered to realize lithium secondary batteries suitable for these applications. Among them, lithium-nickel composite oxides, lithium-nickel-manganese-cobalt composite oxides, lithium-nickel-cobalt-aluminum composite oxides, and lithium-cobalt composite oxides are primarily used as cathode active materials. With the recent surge in demand for large-capacity or high-energy-density lithium secondary batteries, there is a need to develop cathode active materials that simultaneously improve stability and performance.

[0004] A method for manufacturing a positive electrode active material containing a layered lithium nickel-manganese-based composite oxide improves the performance of a lithium secondary battery at high temperature and high voltage by introducing an optimal coating layer, and enhances capacity characteristics, initial charge / discharge efficiency, and high-temperature life characteristics.

[0005] In one embodiment, a method for manufacturing an anode active material is provided, comprising: (1) preparing a core particle containing a layered lithium nickel-manganese-based composite oxide, in the form of a secondary particle, a single particle, or a combination thereof in which a plurality of primary particles are aggregated; (2) washing the core particle by mixing one or more of an aluminum raw material and a boron raw material, the core particle, and washing water; (3) obtaining a washed product by removing a portion of the washing water such that the washing water is included in an amount of 1% to 10% by weight relative to 100% by weight of the core particle and washing water; and (4) introducing the washed product and a tungsten raw material into a mixer and heat-treating at 300°C to 400°C.

[0006] In another embodiment, a positive active material is provided that is manufactured by the method for manufacturing the positive active material.

[0007] In another embodiment, a lithium secondary battery is provided comprising a positive electrode including the positive active material; a negative electrode; and an electrolyte.

[0008] According to a method for manufacturing a positive electrode active material according to one embodiment, an optimal coating layer can be introduced on the surface of the positive electrode active material efficiently and by simplifying the process, and the positive electrode active material and lithium secondary battery to which the method for manufacturing the positive electrode active material is applied can exhibit high initial charge / discharge capacity and efficiency, and can achieve long lifespan characteristics.

[0009] FIG. 1 is a schematic perspective view showing a portion of a cylindrical lithium secondary battery cut off.

[0010] Figure 2 is a cross-sectional view schematically illustrating a prismatic lithium secondary battery.

[0011] Figures 3 and 4 are schematic exploded perspective views of a pouch-type lithium secondary battery.

[0012] Specific embodiments are described below in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0013] The terms used herein are for describing exemplary embodiments only and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0014] Here, "combinations of these" refers to mixtures of components, laminates, composites, copolymers, alloys, blends, reaction products, etc.

[0015] The terms "include," "equip," or "have" used herein are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0016] In the drawings, thicknesses have been enlarged to clearly represent various layers and regions, and the same reference numerals have been used for similar parts throughout the specification. When a part such as a layer, film, region, or plate is described as being "on" or "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between. Conversely, when a part is described as being "immediately on" another part, it means that there is no other part in between.

[0017] Here, “layer” includes not only the shape formed on the entire surface when observed in a plan view, but also the shape formed on some surfaces.

[0018] The average particle size can be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by using transmission electron microscope or scanning electron microscope images. Alternatively, the average particle size value can be obtained by measuring using dynamic light scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Unless otherwise defined, the average particle size is the diameter (D) of the particle at which the cumulative volume in the particle size distribution is 50 volume percent. 50 It may mean ). In addition, unless otherwise defined, the average particle size is obtained by measuring the size (diameter or length of the major axis) of approximately 20 randomly selected particles from scanning electron microscope images to obtain a particle size distribution, and the diameter (D) of the particle with a cumulative volume of 50% in the said particle size distribution. 50 It may be that ) was taken as the average particle size.

[0019] Here, “or” is not interpreted in an exclusive sense; for example, “A or B” is interpreted to include A, B, A+B, etc.

[0020] Here, “metal” is interpreted as a concept including common metals, transition metals, and metalloids (semimetals).

[0021] Method for manufacturing positive electrode active material

[0022] In one embodiment, a method for manufacturing an anode active material is provided, comprising: (1) preparing a core particle containing a layered lithium nickel-manganese-based composite oxide, in the form of a secondary particle, a single particle, or a combination thereof in which a plurality of primary particles are aggregated; (2) washing the core particle by mixing one or more of an aluminum raw material and a boron raw material with the core particle and washing water; (3) obtaining a washed product by removing a portion of the washing water such that the washing water is included in an amount of 1% to 10% by weight relative to 100% by weight of the core particle and washing water; and (4) introducing the washed product and a tungsten raw material into a mixer and heat-treating at 300°C to 400°C.

[0023] With the recent surge in the price of the rare metal cobalt, there is a growing demand for the development of cathode active materials that exclude or reduce the cobalt content. Among these, cathode active materials with olivine-based crystal structures, such as lithium iron phosphate (LFP), lithium manganese phosphate (LMP), and lithium iron manganese phosphate (LMFP), or spinel-based crystal structures, such as lithium manganese oxide (LMO), face limitations in achieving high capacity due to the low available lithium capacity within their structures. Layered lithium nickel-manganese cathode active materials are suitable for high-capacity batteries due to their excellent capacity and efficiency characteristics resulting from high available lithium capacity within their structures; however, the removal of cobalt, which plays a key role in the layered structure, leads to reduced structural stability, increased resistance, and difficulties in ensuring long lifespan characteristics. Furthermore, the exclusion of cobalt accelerates side reactions between the cathode active material and the electrolyte under high voltage and high temperature conditions, resulting in increased gas generation and degraded lifespan characteristics.

[0024] In one embodiment, a method is proposed to improve not only high voltage high temperature lifespan characteristics but also initial charge / discharge efficiency by introducing a coating layer on the surface of a core particle containing a layered lithium nickel-manganese-based composite oxide, which is in the form of a secondary particle formed by aggregating a plurality of primary particles, a single particle, or a combination thereof, thereby reinforcing the particle surface and simultaneously forming a coating layer having a structural 3D lithium channel.

[0025] In addition, a primary heat treatment is performed in the step of preparing a core particle containing a layered lithium nickel-manganese-based composite oxide, which is in the form of a secondary particle formed by the aggregation of multiple primary particles, a single particle, or a combination thereof. However, due to the problem of high residual lithium on the surface of the core particle after the primary heat treatment, a cleaning process is required, and a drying process is performed after the cleaning process. Furthermore, since a secondary heat treatment must be performed separately after the drying process, there is a problem of increased processing costs and reduced production volume. Accordingly, according to the method for manufacturing a cathode active material according to one embodiment, the drying process and the secondary heat treatment after the cleaning process are performed as a single process rather than as separate steps, thereby reducing processing costs. In addition, by coating one or more of aluminum and boron using a wet coating method while the filter press is operating during the cleaning process, and coating aluminum and / or tungsten using a wet coating method while the mixer is operating after the cleaning process, or by spraying tungsten in a form dissolved in a solvent while the mixer is operating after the cleaning process, the surface of the cathode active material can be coated more effectively than the conventional coating method, and by performing a drying process simultaneously with the coating, processing costs can be reduced and the coating can be performed uniformly.

[0026] In a method for manufacturing a positive electrode active material according to one embodiment, the step of preparing a core particle containing a layered lithium nickel-manganese-based composite oxide and in the form of a secondary particle, a single particle, or a combination thereof in which a plurality of primary particles are aggregated includes the step of mixing the nickel-manganese-based composite hydroxide and a lithium raw material and performing a first heat treatment. The nickel-manganese-based composite hydroxide serves as a precursor for the core particle and may be in the form of a secondary particle in which a plurality of primary particles are aggregated, and may not contain cobalt or may contain a very small amount of cobalt, for example, may be a cobalt-free nickel-manganese-based composite hydroxide. The nickel-manganese-based composite hydroxide may be manufactured by a general co-precipitation method.

[0027] In the above nickel-manganese composite hydroxide, the nickel content based on 100 mol% of the total metal may be 60 mol% or more, for example, 60 mol% to 80 mol%, 65 mol% to 80 mol%, 70 mol% to 80 mol%, 60 mol% to 79 mol%, 60 mol% to 78 mol%, or 60 mol% to 75 mol%, etc. When the nickel content satisfies the above range, high capacity can be achieved and structural stability can be increased even if the cobalt content is reduced.

[0028] In the above nickel-manganese composite hydroxide, the manganese content based on 100 mol% of the total metal may be 10 mol% or more, for example, 10 mol% to 40 mol%, 15 mol% to 35 mol%, 15 mol% to 30 mol%, or 20 mol% to 30%. When the manganese content satisfies the above range, high capacity can be achieved while increasing the structural stability of the cathode active material and lowering the production cost to increase economic efficiency.

[0029] In addition, when the nickel-manganese composite hydroxide further contains aluminum, the aluminum content based on 100 mol% of the total metal in the nickel-manganese composite hydroxide may be 0.1 mol% or more, 0.5 mol% or more, or 1 mol% or more, and for example, 1 mol% to 3 mol%, 1 mol% to 2.5 mol%, or 1.5 mol% to 2.5 mol%. When the aluminum content satisfies the above range, it is possible to achieve high capacity while increasing the structural stability of the cathode active material and lowering the production cost to increase economic efficiency.

[0030] A method for manufacturing a positive electrode active material according to one embodiment may use a nickel-manganese-aluminum composite hydroxide as a precursor, in which aluminum is evenly dispersed within the structure by using an aluminum raw material during the preparation of the precursor, without additionally doping aluminum during the preparation of the core particles. When using such a precursor, a positive electrode active material can be manufactured in which the layered structure is stably maintained even during repeated charging and discharging even without cobalt, and since aluminum byproducts or aluminum aggregates are not formed, the capacity, efficiency, and lifespan characteristics of the positive electrode active material can be improved.

[0031] In the above nickel-manganese-based composite hydroxide, the content of cobalt based on 100 mol% of the total metal may be 0.01 mol% or less, 0.005 mol% or less, or 0.001 mol% or less, for example, 0 mol% to 0.01 mol%, 0 mol% to 0.005 mol%, or 0 mol% to 0.001 mol%. Such a nickel-manganese-based composite hydroxide can be said to be economical as it avoids the increase in unit cost caused by cobalt, and can maximize capacity and improve structural stability.

[0032] The above nickel-manganese complex hydroxide can be represented by the following chemical formula 1 as an example.

[0033] [Chemical Formula 1]

[0034] Ni x1Mn y1 Al z1 M 1 w1 (OH)2

[0035] In Chemical Formula 1, 0.6≤x1≤0.8, 0.1≤y1≤0.4, 0≤z1≤0.03, 0≤w1≤0.3, and 0.9≤x1+y1+z1+w1≤1.1, and M 1 It is one or more elements selected from B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zr and Zn.

[0036] In Chemical Formula 1, for example, 0.6≤x1≤0.8, 0.1≤y1≤0.39, 0.01≤z1≤0.03, and 0≤w1≤0.29.

[0037] The nickel-manganese-based composite hydroxide may be in the form of particles, and the average particle size (D) of the particles 50 ) can be 2 μm to 15 μm, for example 8 μm to 15 μm, 9 μm to 14 μm, 2 μm to 5 μm, 3 μm to 5 μm, or 3.5 μm to 4.5 μm.

[0038] The nickel-manganese-based composite hydroxide and lithium raw material can be mixed in a molar ratio of 1:0.9 to 1:1.8, for example, in a molar ratio of 1:0.9 to 1:1.5 or 1:1 to 1:1.2.

[0039] The first heat treatment above may be carried out in an oxygen atmosphere, for example, in a temperature range of 700°C to 1000°C, 800°C to 1000°C, 750°C to 950°C, 780°C to 900°C, 810°C to 890°C, or 850°C to 950°C.

[0040] A layered lithium nickel-manganese-based composite oxide can be obtained through the above first heat treatment.

[0041] In the above layered lithium nickel-manganese composite oxide, the nickel content based on 100 mol% of the total metal excluding lithium may be 60 mol% or more, for example, 60 mol% to 80 mol%, 65 mol% to 80 mol%, 70 mol% to 80 mol%, 60 mol% to 79 mol%, 60 mol% to 78 mol%, or 60 mol% to 75 mol%, etc. When the nickel content satisfies the above range, high capacity can be achieved, and structural stability can be increased even if the cobalt content is reduced. Nickel is contained in the core particles but may migrate to some coating layers during the coating process; therefore, the nickel content may refer to the nickel content contained in the entire cathode active material.

[0042] In the above layered lithium nickel-manganese composite oxide, the manganese content based on 100 mol% of the total metal excluding lithium may be 10 mol% or more, for example, 10 mol% to 40 mol%, 15 mol% to 35 mol%, 15 mol% to 30 mol%, or 20 mol% to 30%. When the manganese content satisfies the above range, high capacity can be achieved while increasing the structural stability of the cathode active material and lowering production costs to improve economic efficiency. Although manganese is contained in the core particles, it may migrate to a partial coating layer during the coating process; therefore, the manganese content may refer to the manganese content contained in the entire cathode active material.

[0043] The above-described layered lithium nickel-manganese composite oxide may, for example, be a lithium nickel-manganese-aluminum composite oxide containing aluminum in addition to nickel and manganese. When aluminum is contained in the above-described layered lithium nickel-manganese composite oxide, it is advantageous to maintain a stable layered structure even if the cobalt element is excluded from the structure. In the above-described layered lithium nickel-manganese composite oxide, the aluminum content based on 100 mol% of the total metal excluding lithium may be 0.1 mol% or more, 0.5 mol% or more, or 1 mol% or more, and for example, 1 mol% to 3 mol%, 1 mol% to 2.5 mol%, or 1.5 mol% to 2.5 mol%. Here, the aluminum content refers to the content of aluminum present within the core particles. When the aluminum content satisfies the above range, a stable layered structure can be maintained even if cobalt is excluded from the core particles, the problem of structural collapse due to charging and discharging can be suppressed, and the long lifespan characteristics of the cathode active material can be realized.

[0044] According to one embodiment, the concentration of aluminum within the core particle may be uniform. That is, it means that the aluminum concentration within the core particle does not have a gradient from the center to the surface, or that the aluminum concentration is not higher or lower outside than inside the core particle, and that the aluminum within the core particle is evenly dispersed. This can be described as a structure obtained by synthesizing a composite oxide using a nickel-manganese-aluminum hydroxide as a precursor, by using aluminum raw materials when manufacturing the precursor, without additionally doping aluminum during the synthesis process of the core particle. The core particle may be in the form of a secondary particle formed by the aggregation of multiple primary particles, a single particle, or a combination thereof; the aluminum content within the primary particle may be the same or similar regardless of the position of the primary particle, and the aluminum content within the single particle may be the same or similar regardless of the position of the single particle. In other words, if a primary particle is selected at an arbitrary location in the cross-section of a secondary particle and the aluminum content is measured inside the primary particle rather than at its interface, the aluminum content can be described as identical, similar, or uniform regardless of the location of the primary particle—that is, whether the primary particle is close to the center or the surface of the secondary particle. Additionally, if the aluminum content is measured at an arbitrary location in the cross-section of a single particle, the aluminum content can be described as identical, similar, or uniform regardless of the measurement location. In such a structure, a stable layered structure can be maintained even if cobalt is absent or present in minute quantities, and since no aluminum byproducts or aluminum aggregates are generated, the capacity, efficiency, and lifespan characteristics of the cathode active material can be simultaneously improved.

[0045] The above layered lithium nickel-manganese composite oxide can be specifically represented by the following chemical formula 2.

[0046] [Chemical Formula 2]

[0047] Li a2 Ni x2 Mn y2 Alz2 M 2 w2 O 2-b2 X b2

[0048] In Chemical Formula 2, 0.9≤a2≤1.8, 0.6≤x2≤0.8, 0.1≤y2≤0.4, 0≤z2≤0.03, 0≤w2≤0.3, 0.9≤x2+y2+z2+w2≤1.1, and 0≤b2≤0.1, and M 2 is one or more elements selected from B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zr and Zn, and X is one or more elements selected from F, P and S.

[0049] In Chemical Formula 2, 0.9≤a2≤1.5 or 0.9≤a2≤1.2 may be present. Additionally, Chemical Formula 2 may contain aluminum, in which case 0.6≤x2≤0.8, 0.1≤y2≤0.39, 0.01≤z2≤0.03, and 0≤w2≤0.29 may be present.

[0050] In Chemical Formula 2, for example, 0.6≤x2≤0.79, 0.6≤x2≤0.78, 0.6≤x2≤0.75, 0.65≤x2≤0.8, or 0.7≤x2≤0.79, 0.1≤y2≤0.35, 0.1≤y2≤0.30, 0.1≤y2≤0.29, 0.15≤y2≤0.39, or 0.2≤y2≤0.3, and 0.01≤z2≤0.025, 0.01 <z2≤0.02, 또는 0.01<z2≤0.019일 수 있고, 0≤w2≤0.28, 0≤w2≤0.27, 0≤w2≤0.26, 0≤w2≤0.25, 0≤w2≤0.24, 0≤w2≤0.23, 0≤w2≤0.22, 0≤w2≤0.21, 0≤w2≤0.2, 0≤w2≤0.15, 0≤w2≤0.1, 또는 0≤w2≤0.09 등일 수 있다.

[0051] The above-described layered lithium nickel-manganese composite oxide may, for example, be a cobalt-free compound that does not contain cobalt or contains a very small amount of cobalt, and the cobalt content based on 100 mol% of the total metal excluding lithium may be 0.01 mol% or less, 0.005 mol% or less, or 0.001 mol% or less, for example, 0 mol% to 0.01 mol%, 0 mol% to 0.005 mol%, or 0 mol% to 0.001 mol%. Such a layered nickel-manganese composite oxide can be economical as it avoids the increase in unit cost caused by cobalt, and can be said to maximize capacity and improve structural stability.

[0052] The core particle may be in the form of a secondary particle formed by the aggregation of a plurality of primary particles. The secondary particle may be spherical, elliptical-spherical, polyhedron, or irregular in shape, and the primary particle may be spherical, elliptical-spherical, plate-shaped, or a combination thereof. In this case, the average particle size (D) of the core particle 50 The depth can be 8 μm to 15 μm, for example, 9 μm to 14 μm. By applying core particles in the form of secondary particles, the density of the final cathode active material can be increased, and the capacity, charge / discharge efficiency, rate characteristics, output characteristics, etc., can be improved.

[0053] The above-mentioned core particle may be in the form of a single particle. A single particle refers to a particle that exists independently without grain boundaries within it and consists of a single particle; morphologically, it may refer to a single particle, monolith structure, monolithic structure, or non-aggregated particle existing in an independent phase where the particles are not mutually aggregated, and as an example, it may be a single crystal. Single particles may exist individually or may be aggregated together. For example, 2 to 10 single particles may be aggregated and in contact with each other. In this case, the average particle size (D) of the core particle 50 ) can be 2 μm to 5 μm, for example 3 μm to 5 μm, or 3.5 μm to 4.5 μm.

[0054] According to one embodiment, a layered lithium nickel-manganese composite oxide having a nickel content of 60 mol% to 80 mol% based on 100 mol% of the total metal excluding lithium has a significantly different residual lithium content on the particle surface and different surface characteristics compared to oxides of other compositions, making it impossible to form a good coating layer in the form of a uniform film using conventional coating methods. In one embodiment, a method is proposed to very uniformly coat the particle surface of a layered lithium nickel-manganese composite oxide.

[0055] In a method for manufacturing a positive electrode active material according to one embodiment, one or more of an aluminum raw material and a boron raw material, the core particle, and cleaning water (distilled water) can be introduced into a filter press and mixed to clean the core particle. In this process, cleaning and coating of the core particle can be performed simultaneously, thereby simplifying the process, reducing processing costs, and increasing production volume. At this time, the core particle and cleaning water can be mixed in a weight ratio of 0.5:1 to 1:1 to clean the core particle, for example, in a weight ratio of 0.6:1 to 1:1 or 0.7:1 to 0.9:1 to clean the core particle. Additionally, the step of cleaning the core particle by mixing one or more of an aluminum raw material and a boron raw material, the core particle, and cleaning water can be performed for 1 minute to 30 minutes, for example, for 1 minute to 10 minutes. In the step of preparing core particles containing a layered lithium nickel-manganese composite oxide through a cleaning process, residual lithium after the first heat treatment can be removed. When conditions such as the weight ratio of the core particles to the cleaning water and the cleaning time are satisfied, residual lithium on the surface of the core particles containing the layered lithium nickel-manganese composite oxide can be effectively removed, while simultaneously suppressing the problem of capacity reduction caused by the leaching of lithium inside the core particles.

[0056] The above aluminum raw material may be fed into a filter press in a form dissolved in an aqueous solvent. The above aqueous solvent may include distilled water, an alcohol-based solvent, or a combination thereof. The above aluminum raw material may be aluminum sulfate, aluminum sulfate hydrate, aluminum nitrate, aluminum nitrate hydrate, or a combination thereof, and may be, for example, aluminum nitrate hydrate.

[0057] The above boron raw material may be fed into a filter press in a form dissolved in an aqueous solvent. The above boron raw material may be boronic acid (H3BO3), boron sulfate, boron nitride, or a combination thereof, and may be boronic acid as an example.

[0058] In step (2) above, aluminum raw materials may be mixed, and based on the total aluminum of the aluminum raw materials and the total aluminum of the core particles excluding lithium, the aluminum content of the aluminum raw materials may be 0.1 mol% to 1.0 mol%, for example, 0.2 mol% to 0.8 mol%, 0.3 mol% to 0.7 mol%, 0.1 mol% to 0.5 mol%, 0.2 mol% to 0.5 mol%, 0.2 mol% to 0.3 mol%, or 0.4 mol% to 0.6 mol%. By adding aluminum content within the above range, a coating layer having a uniform thickness with a thin thickness of several nanometers to several hundred nanometers can be formed, and the amount of gas generated by the lithium secondary battery under high voltage or high temperature operating conditions can be reduced and high capacity and long life characteristics can be improved.

[0059] In step (2) above, the boron raw material may be mixed, and based on the total boron content of the boron raw material and the total metal excluding lithium in the core particles and 100 mol% of the boron content, the boron content in the boron raw material may be 0.1 mol% to 1.0 mol%, for example, 0.2 mol% to 0.8 mol%, 0.3 mol% to 0.7 mol%, or 0.4 mol% to 0.6 mol%. By adding boron content within the above range, a coating layer having a uniform thickness with a thin thickness of several nanometers to several hundred nanometers can be formed, and the amount of gas generated in the lithium secondary battery under high voltage or high temperature operating conditions can be reduced and high capacity and long life characteristics can be improved.

[0060] In the step of obtaining a cleaned product by removing cleaning water according to one embodiment, a portion of the cleaning water may be removed such that the cleaning water is included in an amount of 1% to 10% by weight relative to the total 100% by weight of the core particles and cleaning water, for example, a portion of the cleaning water may be removed such that the cleaning water is included in an amount of 5% to 10% by weight or 7% to 10% by weight. A product from which a portion of the cleaning water has been removed in this manner may be referred to as a cleaned product, and the cleaned product may include 90% to 99% by weight of core particles and 1% to 10% by weight of cleaning water, or 90% to 95% by weight of core particles and 5% to 10% by weight of cleaning water, or 90% to 93% by weight of core particles and 7% to 10% by weight of cleaning water. When the cleaning water is included in the cleaning product within the above range, the mixing of the anode active materials is smoothly performed during the subsequent drying process, and at the same time, one or more of aluminum and tungsten are dissolved in the remaining cleaning water, so that the coating can be performed uniformly.

[0061] In a method for manufacturing a positive electrode active material according to one embodiment, a cleaning product containing 1% to 10% by weight of cleaning water relative to 100% by weight of the total cleaning water and a tungsten raw material are introduced into a mixer, and at this time, an aluminum raw material may be further introduced into the mixer. In this process, drying of the cleaning product and coating of the positive electrode active material can be carried out simultaneously, thereby simplifying the process, reducing processing costs, and increasing production volume. Additionally, by mixing the cleaning product containing 1% to 10% by weight of cleaning water and the tungsten raw material, the tungsten raw material may be partially dissolved in the remaining cleaning water, and accordingly, tungsten can be uniformly coated in a thin thickness on the surface of the positive electrode active material, and aluminum can also be uniformly coated in a thin thickness. Accordingly, the manufactured positive electrode active material can achieve excellent capacity characteristics and lifespan characteristics. The above mixer is suitable for drying a cleaning product containing 1% to 10% by weight of cleaning water and is suitable for mixing the cleaning product and tungsten raw material, and is also suitable for heat treatment to ensure that tungsten is uniformly coated on the surface of the anode active material.

[0062] The above tungsten raw material may be introduced into a mixer in a form dissolved in an aqueous solvent. The above aqueous solvent may include distilled water, an alcohol-based solvent, or a combination thereof. Additionally, the above aluminum raw material may be introduced into a mixer in a form dissolved in an aqueous solvent. The above aluminum raw material may be aluminum sulfate, aluminum sulfate hydrate, aluminum nitrate, aluminum nitrate hydrate, or a combination thereof, and may be, for example, aluminum nitrate hydrate. The above tungsten raw material may be an organic tungsten material, and for example, ammonium metatungsten hydrate (H 26 N6O 40 W 12-H2O) may be used. Ammonium metatungsten hydrate is an optimal raw material for forming a uniform tungsten coating layer on the surface of a layered lithium nickel-manganese composite oxide, after which the organic portion is removed upon drying. Based on the total metal excluding lithium in the core particles and 100 mol% of the total tungsten in the tungsten raw material, the tungsten content in the tungsten raw material may be 0.01 mol% to 0.1 mol%, for example, 0.01 mol% to 0.05 mol%, 0.02 mol% to 0.05 mol%, 0.02 mol% to 0.04 mol%, 0.01 mol% to 0.04 mol%, 0.01 mol% to 0.03 mol%, or 0.02 mol% to 0.03 mol%. By adding tungsten within the above range, a coating layer with a uniform thickness and a thin thickness of several nanometers to several hundred nanometers can be formed, and the amount of gas generated in the lithium secondary battery under high voltage or high temperature operating conditions can be reduced and high capacity and long life characteristics can be improved.

[0063] Based on the total amount of aluminum in the aluminum raw material, excluding lithium from the core particles, and 100 mol% of the total amount of aluminum, the aluminum content in the aluminum raw material may be 0.1 mol% to 1.0 mol%, for example, 0.2 mol% to 0.8 mol%, 0.2 mol% to 0.6 mol%, or 0.2 mol% to 0.4 mol%. By adding aluminum within the above range, a coating layer having a uniform thickness with a thin thickness of several nanometers to several hundred nanometers can be formed, and the amount of gas generated by the lithium secondary battery under high voltage or high temperature operating conditions can be reduced, and high capacity and long life characteristics can be improved.

[0064] After adding the tungsten raw material to the aqueous solvent, the mixing time can be carried out for 1 minute to 60 minutes, for example, 3 minutes to 30 minutes, or 5 minutes to 10 minutes. In addition, the mixing speed can be 2 RPM to 20 RPM, for example, 3 RPM to 15 RPM, or 3 RPM to 10 RPM. Through these mixing conditions, the tungsten raw material can be completely dissolved in the aqueous solvent, the aluminum raw material can be further dissolved in the aqueous solvent, and a uniform coating layer according to one embodiment can be effectively formed.

[0065] In a method for manufacturing a positive electrode active material according to one embodiment, a coating layer can be formed on the surface of a core particle by introducing the cleaning product and the tungsten raw material into a mixer and heat-treating at 300°C to 400°C.

[0066] One embodiment can be described as applying optimal conditions for forming a uniform coating layer on core particles containing a layered lithium nickel-manganese composite oxide by lowering the residual lithium content on the surface by cleaning the core particles and then proceeding with coating. Unlike the wet pre-addition method, in which the salt, which is the coating raw material, is completely dissolved first and then the core particles are added; the wet post-addition method, in which the core particles are added and then the salt, which is the coating raw material, is added; and the dry method, in which the core particles in powder form and the coating raw material in powder form are mixed and heat-treated, one embodiment can be described as applying optimal conditions for forming a uniform coating layer on core particles containing a layered lithium nickel-manganese composite oxide by lowering the residual lithium content on the surface by cleaning the core particles using an aqueous solvent, introducing one or more of the boron raw material and aluminum raw material into a filter press during cleaning to proceed with coating of one or more of the boron and aluminum, and proceeding with coating using a wet coating method while the mixer is operating after the cleaning process.

[0067] In a method for manufacturing a positive electrode active material according to one embodiment, the cleaning product and the tungsten raw material may be introduced into a mixer that mixes at a speed of 50 RPM or less, for example, the cleaning product and the tungsten raw material may be introduced into a mixer that mixes at a speed of 20 RPM or less. A mixer that mixes at a speed of 50 RPM or less may be, for example, a Rödige mixer. When the speed of the mixer falls within the above range, it is possible to prevent the cleaning product inside the mixer from not mixing smoothly due to moisture, and to simultaneously proceed with coating while smoothly drying the cleaning product.

[0068] At this time, the cleaning product introduced into the mixer may contain 1% to 10% by weight of cleaning water relative to 100% by weight of the core particles and cleaning water, for example, 5% to 10% by weight of cleaning water, or 7% to 10% by weight of cleaning water. When the cleaning water is included in the cleaning product within the above range, the mixing of the cathode active materials is performed smoothly during the subsequent drying process, and at the same time, tungsten is dissolved in the remaining cleaning water, allowing the coating to be performed uniformly.

[0069] A method for manufacturing a positive electrode active material according to one embodiment may include the step of introducing the cleaned product and tungsten raw material into a mixer that mixes at a speed of 50 RPM or less, and heat treating at 300°C to 400°C, for example, and may include the step of heat treating at 350°C to 390°C. Generally, a drying process is performed at about 200°C after the cleaning process, and a secondary heat treatment is performed at about 800°C after the drying process. According to the method for manufacturing a positive electrode active material according to one embodiment, these drying process and secondary heat treatment are not performed as separate processes but are performed as a single process at a low temperature, thereby reducing processing costs and allowing for uniform coating.

[0070] In a method for manufacturing a positive electrode active material according to one embodiment, after step (3), the method may further include a step (3-2) of adding and mixing a tungsten raw material into an aqueous solvent to prepare a coating solution containing the tungsten raw material. In the step of adding and mixing the tungsten raw material into an aqueous solvent to prepare the coating solution, the aqueous solvent may include distilled water, an alcohol-based solvent, or a combination thereof. The tungsten raw material may be a tungsten organic material, and as an example, ammonium metatungsten hydrate (H 26 N6O 40 W 12 -H2O) can be used. Ammonium metal tungsten hydrate is the optimal raw material for forming a uniform tungsten coating layer on the surface of a layered lithium nickel-manganese composite oxide, after which the organic portion is removed upon drying.

[0071] Based on the total metal excluding lithium in the core particles and the total tungsten content of the tungsten raw material being 100 mol%, the tungsten content in the tungsten raw material may be 0.01 mol% to 0.5 mol%, for example, 0.01 mol% to 0.2 mol%, 0.02 mol% to 0.2 mol%, 0.02 mol% to 0.15 mol%, 0.02 mol% to 0.15 mol%, 0.02 mol% to 0.1 mol%, or 0.02 mol% to 0.05 mol%. By adding tungsten within the above range, a coating layer having a uniform thickness with a thin thickness of several nanometers to several hundred nanometers can be formed, and the amount of gas generated by the lithium secondary battery under high voltage or high temperature operating conditions can be reduced, and high capacity and long life characteristics can be improved.

[0072] After adding the tungsten raw material to the aqueous solvent, the stirring time can be carried out for 1 minute to 60 minutes, for example, 3 minutes to 30 minutes, or 5 minutes to 30 minutes. In addition, the mixing speed can be 2 RPM to 20 RPM, for example, 3 RPM to 15 RPM, or 3 RPM to 10 RPM. Through these mixing conditions, the tungsten raw material can be completely dissolved in the aqueous solvent, and a uniform coating layer according to one embodiment can be effectively formed.

[0073] In one embodiment, when the tungsten raw material is added to an aqueous solvent and mixing is stopped, that is, when the pH range of the supernatant of the coating solution is 2.5 to 6.0, for example, 3.0 to 5.5, or 3.0 to 4.5. If the pH of the supernatant is less than 2.5, the acidity becomes strong and a uniform coating layer may not be formed, and if the pH is greater than 6.0, the basicity becomes strong and it may also be difficult to form a uniform coating layer in this case.

[0074] In a method for manufacturing a positive electrode active material according to one embodiment, a cleaning product containing 1% to 10% by weight of cleaning water relative to 100% by weight of the core particles and cleaning water is introduced into a mixer, and the coating solution can be sprayed. That is, in step (4), introducing the tungsten raw material into the mixer may involve introducing the coating solution containing the tungsten raw material by spraying it into the mixer. In this process, drying of the cleaning product and coating of the positive electrode active material can be performed simultaneously, thereby simplifying the process, reducing processing costs, and increasing production volume. Additionally, by spraying the coating solution containing the tungsten raw material onto the cleaning product containing 1% to 10% by weight of cleaning water, the tungsten raw material may be partially dissolved in the remaining cleaning water, and accordingly, tungsten can be uniformly coated on the surface of the positive electrode active material in a thin thickness. Accordingly, the manufactured positive electrode active material can achieve excellent capacity characteristics and lifespan characteristics. The above mixer is equipment suitable for drying a cleaning product containing 1% to 10% by weight of cleaning water, and can also be described as equipment capable of appropriate heat treatment to uniformly coat the surface of the positive electrode active material with tungsten.

[0075] In a method for manufacturing a positive electrode active material according to one embodiment, the cleaning product may be introduced into a mixer that mixes at a speed of 50 RPM or less, for example, or into a mixer that mixes at a speed of 20 RPM or less. A mixer that mixes at a speed of 50 RPM or less may be, for example, a Rödige mixer. When the speed of the mixer falls within the above range, it is possible to prevent the positive electrode active material inside the mixer from not mixing smoothly due to moisture, and to simultaneously proceed with coating while smoothly drying the cleaning product.

[0076] At this time, the cleaning product introduced into the mixer may contain 1% to 10% by weight of cleaning water relative to 100% by weight of the total core particles and cleaning water, for example, 5% to 10% by weight of cleaning water, or 7% to 10% by weight of cleaning water. When the cleaning water is included in the cleaning product within the above range, the mixing of the cathode active materials is performed smoothly during the subsequent drying process, and at the same time, tungsten is dissolved in the remaining cleaning water, allowing for a uniform tungsten coating.

[0077] In a method for manufacturing a positive electrode active material according to one embodiment, the step of spraying the coating solution may be performed for 1 to 10 minutes in a mixer that mixes at a speed of 50 RPM or less. Additionally, the step of spraying the coating solution may be performed in the step of starting to heat the mixer, at which time the temperature of the mixer may be 20°C to 80°C, and after spraying the coating solution, the mixer may be continuously heated to 300°C to 400°C. By spraying the coating solution under the above conditions, the surface of the core particle can be coated more effectively than conventional dry coating and wet coating methods, and the drying process can be performed simultaneously with the tungsten coating to reduce processing costs and ensure that the tungsten coating is performed uniformly.

[0078] A method for manufacturing a positive electrode active material according to one embodiment may include the step of introducing the cleaned product into a mixer that mixes at a speed of 50 RPM or less, and heat treating at 300°C to 400°C while spraying the coating solution, and for example, may include the step of heat treating at 350°C to 390°C. Generally, a drying process is performed at about 200°C after the cleaning process, and a secondary heat treatment is performed at about 800°C after the drying process. According to the method for manufacturing a positive electrode active material according to one embodiment, these drying process and secondary heat treatment are not performed as separate processes but are performed as a single process, thereby reducing processing costs and allowing for uniform tungsten coating.

[0079] positive electrode active material

[0080] In one embodiment, a positive electrode active material is provided according to the method for manufacturing the positive electrode active material. By introducing a coating layer on the surface of a core particle containing a layered lithium nickel-manganese-based composite oxide, a method is proposed that can maintain a stable structure even at high voltage, realize high capacity and long lifespan characteristics, and improve high-temperature storage characteristics.

[0081] core particles

[0082] The core particle contains a layered lithium nickel-manganese-based composite oxide and is in the form of a secondary particle formed by the aggregation of a plurality of primary particles, a single particle, or a combination thereof, and the layered lithium nickel-manganese-based composite oxide can be represented by Chemical Formula 2. Since the core particle has been described above, a detailed explanation is omitted.

[0083] The above-mentioned core particles are susceptible to chemical attack from components within the electrolyte when operating the battery under high voltage or high temperature conditions, which can lead to many side reactions with the electrolyte and consequently cause a large amount of gas generation, resulting in reduced battery life and safety. However, these problems can be resolved by introducing a coating layer according to an embodiment to be described later.

[0084] coating layer

[0085] A positive electrode active material according to one embodiment includes a coating layer located on the surface of a core particle and containing one or more of aluminum and boron and tungsten.

[0086] The aluminum content based on 100 mol% of the total metal excluding lithium on the surface of the cathode active material, as measured by SEM-EDS (Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) on the surface of the cathode active material, may be 0.1 mol% to 1.0 mol%, for example, 0.2 mol% to 0.8 mol%, 0.3 mol% to 0.7 mol%, 0.1 mol% to 0.5 mol%, 0.2 mol% to 0.5 mol%, 0.2 mol% to 0.3 mol%, or 0.4 mol% to 0.6 mol%. When the aluminum content according to SEM-EDS analysis satisfies the above range, the cathode active material can achieve excellent capacity and lifespan characteristics by containing a thin layer of aluminum at a high concentration on its surface.

[0087] SEM-EDS can be performed using Helios G4 HX under conditions of HT: 3kV, current: 0.8nA, live time: 90s.

[0088] The tungsten content based on 100 mol% of the total metal excluding lithium on the surface of the cathode active material, as measured by SEM-EDS on the surface of the cathode active material, may be 0.01 mol% to 0.5 mol%, for example, 0.01 mol% to 0.2 mol%, 0.02 mol% to 0.2 mol%, 0.02 mol% to 0.15 mol%, 0.05 mol% to 0.15 mol%, 0.05 mol% to 0.1 mol%, or 0.1 mol% to 0.15 mol%, 0.01 mol% to 0.1 mol%, 0.01 mol% to 0.05 mol%, 0.02 mol% to 0.05 mol%, 0.02 mol% to 0.04 mol%, 0.01 mol% to 0.04 mol%, 0.01 mol% to 0.01 mol% to It may be 0.03 mol%, or 0.02 mol% to 0.03 mol%. When the tungsten content according to SEM-EDS analysis satisfies the above range, the cathode active material can achieve excellent capacity and lifespan characteristics by containing tungsten at a high concentration and thin thickness on the surface.

[0089] The boron content based on 100 mol% of the total metal excluding lithium on the surface of the positive active material, as measured by SEM-EDS on the surface of the positive active material, may be 0.1 mol% to 1.0 mol%, for example, 0.2 mol% to 0.8 mol%, 0.3 mol% to 0.7 mol%, or 0.4 mol% to 0.6 mol%. When the boron content according to SEM-EDS analysis satisfies the above range, the positive active material can achieve excellent capacity and lifespan characteristics by containing a high concentration and thin thickness of boron on its surface.

[0090] According to one embodiment, the coating layer may be in the form of a film that continuously covers the surface of the core particle, or, for example, in the form of a shell that covers the entire surface of the core particle. This is distinguished from a structure in which the coating is partially applied to only a part of the surface of the core particle. According to one embodiment, the coating layer can be formed to completely cover the surface of the core particle while having a very thin and uniform thickness. Accordingly, the resistance of the cathode active material does not increase or the capacity does not decrease, structural stability is improved, side reactions with the electrolyte can be effectively suppressed, gas generation under high voltage and high temperature conditions is reduced, and long life characteristics can be achieved.

[0091] According to one embodiment, the thickness of the coating layer may be 5 nm to 200 nm, for example, 5 nm to 150 nm, 5 nm to 100 nm, 5 nm to 80 nm, 5 nm to 50 nm, or 10 nm to 50 nm. When the coating layer satisfies the above thickness range, the structural stability of the positive electrode active material can be improved and side reactions with the electrolyte can be effectively suppressed without increasing resistance or decreasing capacity due to the coating. The thickness of the coating layer can be measured, for example, through SEM, TEM, TOF-SIMS, XPS, or EDS analysis, and for example, through EDS line profile analysis of the cross-section of the positive electrode active material.

[0092] Meanwhile, the coating layer may further contain nickel, manganese, or a combination thereof in addition to aluminum, boron, and tungsten. Nickel and / or manganese may be introduced during the coating layer formation process from what was contained in the core particles, and their content is not particularly limited. The coating layer according to one embodiment selectively contains nickel and / or manganese and is formed with a thin and uniform thickness, which can improve the high voltage characteristics of the cathode active material and enhance the lifespan characteristics.

[0093] The obtained positive electrode active material may be said to comprise a core particle containing a layered lithium nickel-manganese-based composite oxide, and a coating layer located on the surface of the core particle containing boron oxide, lithium-boron oxide, aluminum oxide, lithium-aluminum oxide, tungsten oxide, lithium-tungsten oxide, or a combination thereof.

[0094] anode

[0095] In one embodiment, a positive electrode is provided that includes a current collector and a positive active material layer located on the current collector, wherein the positive active material layer comprises the aforementioned positive active material. The positive active material layer may further include other types of positive active materials in addition to the aforementioned positive active material. Additionally, the positive active material layer may optionally further include a binder, a conductive material, or a combination thereof.

[0096] bookbinder

[0097] The binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples of binders include, but are not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0098] Challenge

[0099] A conductive material is used to impart conductivity to an electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0100] The content of the binder and the conductive material may be 0.5% to 5% by weight each with respect to 100% by weight of the positive active material layer.

[0101] Al thin films can be used as the positive current collector, but are not limited thereto.

[0102] lithium secondary battery

[0103] In one embodiment, a lithium secondary battery comprising the aforementioned positive electrode, negative electrode, and electrolyte is provided. As an example, the lithium secondary battery may include a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and an electrolyte.

[0104] Lithium secondary batteries can be classified into cylindrical, prismatic, pouch, coin, etc., depending on their shape. FIGS. 1 to 4 are schematic diagrams illustrating a lithium secondary battery according to one embodiment, where FIG. 1 is a cylindrical battery, FIG. 2 is a prismatic battery, and FIGS. 3 and 4 are pouch-type batteries. Referring to FIGS. 1 to 4, the lithium secondary battery (100) may include an electrode assembly (40) having a separator (30) interposed between a positive electrode (10) and a negative electrode (20), and a case (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 (not shown). The lithium secondary battery (100) may include a sealing member (60) that seals the case (50) as in FIG. 1. In addition, in FIG. 2, the lithium secondary battery (100) may include a positive lead tab (11) and a positive terminal (12), a negative lead tab (21) and a negative terminal (22). As shown in FIG. 3 and FIG. 4, the lithium secondary battery (100) may include an electrode tab (70), namely a positive tab (71) and a negative tab (72), which serve as an electrical path to guide the current formed in the electrode assembly (40) to the outside.

[0105] cathode

[0106] The cathode may include a current collector and a cathode active material layer located on the current collector, and the cathode active material layer may include a cathode active material and may further include a binder, a conductive material, or a combination thereof.

[0107] cathode active material

[0108] The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0109] A material capable of reversibly intercalating / deintercalating the above lithium ions may be a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0110] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0111] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The above Si-based negative electrode active material may include silicon, silicon-carbon composites, and SiOx(0 <x≤2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소(Si를 제외함), 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합에서 선택되는 원소이며, 예컨대 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합에서 선택됨), 또는 이들의 조합일 수 있다. 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn 합금 또는 이들의 조합일 수 있다.

[0112] The above silicon-carbon composite may be a composite of silicon and amorphous carbon. The average particle size (D) of the silicon-carbon composite particles50 The thickness may be, for example, 0.5 μm to 20 μm. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, it may include a secondary particle (core) assembled from silicon primary particles and an amorphous carbon coating layer (shell) located on the surface of the secondary particle. The amorphous carbon may also be located between the silicon primary particles, so that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0113] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. Examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0114] When the silicon-carbon composite comprises silicon and amorphous carbon, the silicon content may be 10% to 50% by weight with respect to 100% by weight of the silicon-carbon composite, and the amorphous carbon content may be 50% to 90% by weight. Additionally, when the composite comprises silicon, amorphous carbon, and crystalline carbon, the silicon content may be 10% to 50% by weight with respect to 100% by weight of the silicon-carbon composite, the crystalline carbon content may be 10% to 70% by weight, and the amorphous carbon content may be 20% to 40% by weight.

[0115] In addition, the thickness of the amorphous carbon coating layer may be 5 nm to 100 nm. The average particle size (D) of the silicon particles (primary particles) 50) can be 10 nm to 1 µm, or 10 nm to 200 nm. The silicon particles may exist as silicon alone, in the form of a silicon alloy, or in an oxidized form. The oxidized form of silicon is SiO x (0 <x≤2)로 표시될 수 있다. 이때, 산화 정도를 나타내는 Si:O의 원자 함량 비율은 99:1 내지 33:67일 수 있다. 본 명세서에서, 별도의 정의가 없는 한, 평균 입경(D 50 ) refers to the diameter of the particle with a cumulative volume of 50 volume% in the particle size distribution.

[0116] The above Si-based negative electrode active material or Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material. When the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material are mixed and used, the mixing ratio may be 1:99 to 90:10 by weight.

[0117] bookbinder

[0118] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collector. As the binder, a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof may be used.

[0119] Examples of non-aqueous binders include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyimide, or combinations thereof.

[0120] The water-based binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0121] When a water-based binder is used as the cathode binder, a cellulose-based compound capable of imparting viscosity may be further included. As this cellulose-based compound, one or more types such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof may be mixed and used. Na, K, or Li may be used as the alkali metal.

[0122] The dry binder is a polymer material capable of fiberization, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0123] Challenge

[0124] A conductive material is used to impart conductivity to an electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjenblack, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0125] The content of the negative electrode active material may be 95% to 99.5% by weight with respect to 100% by weight of the negative electrode active material layer, and the content of the binder may be 0.5% to 5% by weight with respect to 100% by weight of the negative electrode active material layer. For example, the negative electrode active material layer may contain 90% to 99% by weight of the negative electrode active material, 0.5% to 5% by weight of the binder, and 0.5% to 5% by weight of the conductive material.

[0126] The whole house

[0127] The negative current collector may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or alloys thereof, and may be in the form of a foil, sheet, or foam. The thickness of the negative current collector may be, for example, 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0128] electrolytes

[0129] The electrolyte for a lithium secondary battery may be, for example, an electrolyte solution, which may include a non-aqueous organic solvent and a lithium salt.

[0130] Non-aqueous organic solvents serve as a medium through which ions involved in the electrochemical reaction of a cell can move. Non-aqueous organic solvents may be carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvents, aprotic solvents, or a combination thereof.

[0131] Carbonate-based solvents that may be used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. Ester-based solvents that may be used include methyl acetate, ethyl acetate, n-propyl acetate, t-butyl acetate, methylpropionate, ethylpropionate, decanolide, mevalonolactone, valerolactone, caprolactone, etc. As ether-based solvents, dibutyl ether, tetraglame, diglame, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. may be used. Additionally, as ketone-based solvents, cyclohexanone, etc. may be used. As alcohol-based solvents, ethyl alcohol, isopropyl alcohol, etc. may be used, and as aprotic solvents, nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane, 1,4-dioxolane; sulfolanes, etc. may be used.

[0132] Non-aqueous organic solvents may be used alone or in a mixture of two or more types, and when two or more types are mixed, the mixing ratio can be appropriately adjusted according to the desired battery performance, which is widely understood by those working in the field.

[0133] When using a carbonate-based solvent, a mixture of cyclic carbonates and chain carbonates can be used, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio of 1:1 to 1:9.

[0134] The non-aqueous organic solvent may further include an aromatic hydrocarbon-based organic solvent. For example, a carbonate-based solvent and an aromatic hydrocarbon-based organic solvent may be mixed and used in a volume ratio of 1:1 to 30:1.

[0135] The electrolyte may further include vinyl ethyl carbonate, vinylene carbonate, or ethylene carbonate-based compounds to improve battery life.

[0136] Representative examples of the above ethylene carbonate compounds include fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, and cyanoethylene carbonate.

[0137] Lithium salts are substances that dissolve in organic solvents and act as a source of lithium ions within the battery, enabling the basic operation of rechargeable lithium batteries and facilitating the movement of lithium ions between the anode and cathode. Representative examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO2C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide; LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1 It may include one or more selected from SO2)(x and y are integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0138] It is preferable to use a lithium salt concentration within the range of 0.1M to 2.0M. When the lithium salt concentration falls within the above range, the electrolyte has appropriate ionic conductivity and viscosity, so it can exhibit excellent performance and lithium ions can move effectively.

[0139] separator

[0140] Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. As such a separator, polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more layers thereof may be used, and of course, mixed multilayer films such as polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, and polypropylene / polyethylene / polypropylene three-layer separators may be used.

[0141] The above separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0142] The porous substrate may be a polymer membrane formed from any one polymer selected from 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 oxide, cyclic olefin copolymer, polyphenylene sulfide, polyethylene naphthalate, Teflon, and polytetrafluoroethylene, or a copolymer or mixture of two or more of these. The porous substrate may include glass fibers or be a composite membrane of a polymer and glass fibers.

[0143] The porous substrate may have a thickness of about 1 μm to 40 μm, and may have a thickness of, for example, 1 μm to 30 μm, 1 μm to 20 μm, 5 μm to 15 μm, or 10 μm to 15 μm.

[0144] The above organic material may include a (meth)acrylic copolymer comprising a first structural unit derived from (meth)acrylamide, and a second structural unit comprising at least one of a structural unit derived from (meth)acrylic acid or (meth)acrylate and a structural unit derived from (meth)acrylamideidosulfonic acid or its salt.

[0145] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include inorganic particles selected from SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof, but is not limited thereto. The average particle size (D) of the inorganic particles. 50 ) can be 1 nm to 2000 nm, for example, 100 nm to 1000 nm, or 100 nm to 700 nm.

[0146] The above organic and inorganic materials may exist mixed in a single coating layer, or may exist in a stacked form with a coating layer containing organic materials and a coating layer containing inorganic materials.

[0147] The thickness of the coating layer may be 0.5 μm to 20 μm, for example, 1 μm to 10 μm, or 1 μm to 5 μm.

[0148] Examples and comparative examples of the present invention are described below. The following examples are merely illustrative of the present invention, and the present invention is not limited to the following examples.

[0149] Example 1

[0150] 1. Preparation of positive electrode active material

[0151] Average particle size (D 50 Ni with a ) of approximately 4 µm 0.75 Mn 0.245 Al 0.005 (OH)2 and LiOH are mixed in a 1:1 molar ratio and subjected to a first heat treatment at 900°C for 8 hours in an oxygen atmosphere to obtain a composition of LiNi 0.75 Mn 0.245 Al 0.005 O2 and average particle size (D 50 A layered lithium nickel-manganese composite oxide with a particle size of approximately 4 μm was prepared. The layered lithium nickel-manganese composite oxide was ground using an Air-Jet to obtain a single-particle form with an average particle size (D). 50 Core particles containing a layered lithium nickel-manganese-based composite oxide with a thickness of approximately 4 μm were prepared.

[0152] Two tons of distilled water (washing water), two tons of manufactured core particles, and aluminum nitrate hydrate (Al(NO3)3-9H2O) were added to a 10,000 L mixer (Rödige), and stirred for about 5 minutes to prepare a first mixed solution. Subsequently, the washing water was removed from the first mixed solution using a filter press until the residual distilled water was 10% by weight relative to the total 100% by weight of the core particles and washing water, thereby obtaining a washed product. At this time, the aluminum content in the aluminum nitrate hydrate was added in an amount of 0.2 mol% relative to the total 100 mol% of metals excluding lithium in the finally manufactured cathode active material.

[0153] Distilled water and ammonium metatungsten hydrate (H 26 N6O 40 W 12A second mixed solution was prepared by adding (-H2O) and stirring for about 30 minutes. At this time, distilled water was added in an amount of 5 wt% relative to 100 wt% of the total cathode active material finally prepared, and the tungsten content in the ammonium metatungsten hydrate was added in an amount of 0.025 mol% relative to 100 mol% of the total metals excluding lithium in the cathode active material finally prepared.

[0154] The above cleaning product and the second mixing solution were introduced into the above mixer (Rödige), and while mixing at a speed of 5 RPM, the mixer was heated to 380°C at a heating rate of 2.5°C / min, and heat treatment (drying and coating) was performed simultaneously for a total of 5 hours to obtain an anode active material.

[0155] 2. Manufacture of coin-type half-batteries

[0156] A cathode active material slurry was prepared by mixing 98.5 wt% of the manufactured cathode active material, 1.0 wt% of a polyvinylidene fluoride binder, and 0.5 wt% of a carbon nanotube conductive material, and the slurry was coated onto an aluminum foil current collector, dried, and rolled to produce a cathode.

[0157] A coin-type half-cell was manufactured using the above-mentioned positive electrode, lithium metal counter electrode, and electrolyte by a conventional method. Polytetrafluoroethylene separator was used as the electrolyte, and an electrolyte solution was used in which 1M LiPF6 was dissolved in a solvent mixed with ethylene carbonate and dimethyl carbonate in a volume ratio of 3:7.

[0158] Example 2

[0159] A positive electrode active material and a coin-type half-cell were manufactured in substantially the same manner as in Example 1, except that in the manufacture of the positive electrode active material, the amount of aluminum in the aluminum nitrate hydrate was 0.3 mol% relative to 100 mol% of the total metal excluding lithium in the finally manufactured positive electrode active material.

[0160] Example 3

[0161] A positive electrode active material and a coin-type half-cell were manufactured in substantially the same manner as in Example 1, except that in the manufacture of the positive electrode active material, the amount of aluminum in the aluminum nitrate hydrate was 0.4 mol% relative to 100 mol% of the total metal excluding lithium in the finally manufactured positive electrode active material.

[0162] Example 4

[0163] A positive electrode active material and a coin-type half-cell were manufactured in substantially the same manner as in Example 1, except that in the manufacture of the positive electrode active material, the amount of aluminum in the aluminum nitrate hydrate was 0.5 mol% relative to 100 mol% of the total metal excluding lithium in the finally manufactured positive electrode active material.

[0164] Example 5

[0165] A positive electrode active material and a coin-type half-cell were manufactured in substantially the same manner as in Example 1, except that in the manufacture of the positive electrode active material, the amount of aluminum in the aluminum nitrate hydrate was 0.6 mol% relative to 100 mol% of the total metal excluding lithium in the finally manufactured positive electrode active material.

[0166] Example 6

[0167] A positive electrode active material and a coin-type half-cell were manufactured in substantially the same manner as in Example 1, except that in the manufacture of the positive electrode active material, the amount of aluminum in the aluminum nitrate hydrate was 0.7 mol% relative to 100 mol% of the total metal excluding lithium in the finally manufactured positive electrode active material.

[0168] Example 7

[0169] Two tons of distilled water (washing water), two tons of core particles prepared in Example 1, and boron acid (H3BO3) were added to a 10,000 L mixer (Rödige), and stirred for about 5 minutes to prepare a first mixed solution. Subsequently, the washing water was removed from the first mixed solution using a filter press until the residual distilled water was 10% by weight relative to the total 100% by weight of the core particles and washing water, thereby obtaining a washed product. At this time, the boron content in the boron acid was added in an amount of 0.25 mol% relative to the total 100 mol% of metals excluding lithium in the finally prepared cathode active material.

[0170] Distilled water, aluminum nitrate hydrate (Al(NO3)3-9H2O) and ammonium metatungsten hydrate (H 26 N6O 40 W 12 A second mixed solution was prepared by adding (-H2O) and stirring for about 30 minutes. At this time, distilled water was added in an amount of 5 wt% relative to 100 wt% of the total cathode active material finally prepared, the aluminum content in the aluminum nitrate hydrate was added in an amount of 0.3 mol% relative to 100 mol% of the total metals excluding lithium in the finally prepared cathode active material, and the tungsten content in the ammonium metatungsten hydrate was added in an amount of 0.02 mol% relative to 100 mol% of the total metals excluding lithium in the finally prepared cathode active material.

[0171] The above cleaning product and the second mixing solution were introduced into the above mixer (Rödige), and while mixing at a speed of 5 RPM, the mixer was heated to 380°C at a heating rate of 2.5°C / min, and heat treatment (drying and coating) was performed simultaneously for a total of 5 hours to obtain an anode active material.

[0172] Subsequently, a coin-type half-cell was manufactured using substantially the same method as in Example 1.

[0173] Example 8

[0174] A positive electrode active material and a coin-type half-cell were prepared in substantially the same manner as in Example 7, except that in the preparation of the positive electrode active material, the boron content in the boron acid was added in an amount of 0.5 mol% relative to 100 mol% of the total metal excluding lithium in the finally prepared positive electrode active material.

[0175] Example 9

[0176] A positive electrode active material and a coin-type half-cell were prepared in substantially the same manner as in Example 7, except that in the preparation of the positive electrode active material, the boron content in the boron acid was added in an amount of 0.75 mol% relative to 100 mol% of the total metal excluding lithium in the finally prepared positive electrode active material.

[0177] Example 10

[0178] A positive electrode active material and a coin-type half-cell were prepared in substantially the same manner as in Example 7, except that in the preparation of the positive electrode active material, the boron content in the boron acid was added in an amount of 1.0 mol% relative to 100 mol% of the total metal excluding lithium in the finally prepared positive electrode active material.

[0179] Example 11

[0180] Average particle size (D 50 Ni with a ) of approximately 14 µm 0.75 Mn 0.23 Al 0.02 (OH)2 and LiOH were mixed in a 1:1 molar ratio and subjected to a first heat treatment at 800°C for 15 hours in an oxygen atmosphere to obtain a composition of LiNi 0.75 Mn 0.23 Al 0.02 O2 and average particle size (D 50 Core particles containing a layered lithium nickel-manganese-based composite oxide in the form of secondary particles with a thickness of approximately 14 μm were prepared.

[0181] Two tons of distilled water (washing water), two tons of manufactured core particles, and aluminum nitrate hydrate (Al(NO3)3-9H2O) were added to a 10,000 L mixer (Rödige), and stirred for about 5 minutes to prepare a first mixed solution. Subsequently, the washing water was removed from the first mixed solution using a filter press until the residual distilled water was 10% by weight relative to the total 100% by weight of the core particles and washing water, thereby obtaining a washed product. At this time, the aluminum content in the aluminum nitrate hydrate was added in an amount of 0.2 mol% relative to the total 100 mol% of metals excluding lithium in the finally manufactured cathode active material.

[0182] Distilled water and ammonium metatungsten hydrate (H 26 N6O 40 W 12 A second mixed solution was prepared by adding (-H2O) and stirring for about 30 minutes. At this time, distilled water was added in an amount of 5 wt% relative to 100 wt% of the total cathode active material finally prepared, and the tungsten content in the ammonium metatungsten hydrate was added in an amount of 0.025 mol% relative to 100 mol% of the total metals excluding lithium in the cathode active material finally prepared.

[0183] The above-mentioned cleaning product was introduced into the above-mentioned mixer (Rödige) and mixed at a speed of 5 RPM, while starting the heating of the mixer at a heating rate of 2.5°C / min, the second mixed solution was sprayed into the mixer for 7 minutes at a temperature of about 60°C, the spraying was stopped and the temperature was continued to be raised to 380°C, and heat treatment (drying and coating) was performed simultaneously for a total of 5 hours to obtain the positive electrode active material.

[0184] Subsequently, a coin-type half-cell was manufactured using substantially the same method as in Example 1.

[0185] Example 12

[0186] A positive electrode active material and a coin-type half-cell were prepared in substantially the same manner as in Example 11, except that in the preparation of the positive electrode active material, the amount of tungsten in the ammonium metatungsten hydrate was 0.05 mol% relative to 100 mol% of the total metal excluding lithium in the finally prepared positive electrode active material.

[0187] Example 13

[0188] A positive electrode active material and a coin-type half-cell were prepared in substantially the same manner as in Example 11, except that in the preparation of the positive electrode active material, the amount of tungsten in the ammonium metatungsten hydrate was 0.1 mol% relative to 100 mol% of the total metal excluding lithium in the finally prepared positive electrode active material.

[0189] Example 14

[0190] A positive electrode active material and a coin-type half-cell were prepared in substantially the same manner as in Example 11, except that in the preparation of the positive electrode active material, the amount of tungsten in the ammonium metatungsten hydrate was 0.15 mol% relative to 100 mol% of the total metal excluding lithium in the finally prepared positive electrode active material.

[0191] Example 15

[0192] A positive electrode active material and a coin-type half-cell were manufactured in substantially the same manner as in Example 11, except that in the manufacture of the positive electrode active material, the amount of tungsten in the ammonium metatungsten hydrate was 0.2 mol% relative to 100 mol% of the total metal excluding lithium in the finally manufactured positive electrode active material.

[0193] Comparative Example 1

[0194] Two tons of distilled water (washing water) and two tons of core particles identical to those prepared in Example 1 were added to a 10,000 L mixer (Rödige), and a mixed solution was prepared by stirring for about 30 minutes. Subsequently, the washing water was removed from the mixed solution using a filter press until the residual distilled water was 10% by weight relative to the total 100% by weight of the core particles and washing water, thereby obtaining a washed product.

[0195] The above-mentioned cleaning product was introduced into the above-mentioned mixer, and the mixer was heated to 380°C while mixing at a speed of 5 RPM and dried for a total of 5 hours to produce a dried product.

[0196] The above dried product and aluminum oxide (Al2O3) were mixed, and a second heat treatment was performed at 400°C for 8 hours in an oxygen atmosphere to produce a positive electrode active material. At this time, the aluminum content in the aluminum oxide was added in an amount of 0.4 mol% relative to 100 mol% of the total metal excluding lithium in the finally produced positive electrode active material.

[0197] Subsequently, a coin-type half-cell was manufactured in substantially the same manner as in Example 1, except that the positive electrode was manufactured using the above positive electrode active material.

[0198] Comparative Example 2

[0199] 600g of distilled water and aluminum nitrate hydrate were added to a 1L reactor, and a coating solution was prepared by stirring at approximately 350 rpm for about 5 minutes for salt dissolution. It was confirmed that the salt was completely dissolved in the coating solution and that it was colorless and transparent. 500g of the same dried product prepared in Comparative Example 1 was added to the coating solution being continuously stirred for 1.5 minutes, and stirred for about 30 minutes. At this time, the aluminum content in the aluminum nitrate hydrate was designed to be 0.2 mol% relative to 100 wt% of the total metal excluding lithium in the finally prepared cathode active material.

[0200] The solvent was removed from the mixed solution using an aspirator and a filter press, and the product was vacuum dried at 190°C to obtain a coated product.

[0201] The above-mentioned coating product was subjected to a second heat treatment at 750°C for 8 hours in an oxygen atmosphere to produce an anode active material.

[0202] Subsequently, a coin-type half-cell was manufactured in substantially the same manner as in Example 1, except that the positive electrode was manufactured using the above positive electrode active material.

[0203] Comparative Example 3

[0204] A positive active material and a coin-type half-cell were manufactured in substantially the same manner as Comparative Example 2, except that in the manufacture of the positive active material, the aluminum content in the aluminum nitrate hydrate was designed to be 0.3 mol% with respect to 100 weight% of the total metal excluding lithium in the finally manufactured positive active material.

[0205] Comparative Example 4

[0206] In the preparation of the positive active material, the positive active material and the coin-type half-cell were prepared in substantially the same manner as in Example 1, except that the second mixed solution was not introduced into the mixer, and the mixer was heated to 450°C instead of 380°C to perform drying and coating simultaneously.

[0207] Comparative Example 5

[0208] Two tons of distilled water (washing water) and two tons of core particles identical to those prepared in Example 11 were added to a 10,000 L mixer (Rödige), and a mixed solution was prepared by stirring for about 30 minutes. Subsequently, the washing water was removed from the mixed solution using a filter press until the residual distilled water was 10% by weight relative to the total 100% by weight of the core particles and washing water, thereby obtaining a washed product.

[0209] The above-mentioned cleaning product was introduced into the above-mentioned mixer, and the mixer was heated to 380°C while mixing at a speed of 5 RPM and dried for a total of 5 hours to produce a dried product.

[0210] The above dried product and aluminum oxide (Al2O3) were mixed, and a second heat treatment was performed at 400°C for 8 hours in an oxygen atmosphere to produce a positive electrode active material. At this time, the aluminum content in the aluminum oxide was added in an amount of 0.5 mol% relative to 100 mol% of the total metal excluding lithium in the finally produced positive electrode active material.

[0211] Subsequently, a coin-type half-cell was manufactured using substantially the same method as in Example 1.

[0212] Comparative Example 6

[0213] 600g of distilled water and aluminum nitrate hydrate were added to a 1L reactor, and a coating solution was prepared by stirring at approximately 350 rpm for about 5 minutes for salt dissolution. It was confirmed that the salt was completely dissolved in the coating solution and that it was colorless and transparent. 500g of the same dried product prepared in Comparative Example 5 was added to the coating solution being continuously stirred for 1.5 minutes, and stirred for about 30 minutes. At this time, the aluminum content in the aluminum nitrate hydrate was designed to be 0.2 mol% relative to 100 wt% of the total metal excluding lithium in the finally prepared cathode active material.

[0214] The solvent was removed from the mixed solution using an aspirator and a filter press, and the product was vacuum dried at 190°C to obtain a coated product.

[0215] The above-mentioned coating product was subjected to a second heat treatment at 750°C for 8 hours in an oxygen atmosphere to produce an anode active material.

[0216] Subsequently, a coin-type half-cell was manufactured using substantially the same method as in Example 1.

[0217] Comparative Example 7

[0218] A positive electrode active material and a coin-type half-cell were manufactured in substantially the same manner as Comparative Example 6, except that in the manufacture of the positive electrode active material, the aluminum content in the aluminum nitrate hydrate was added in an amount of 1.0 mol% relative to 100 mol% of the total metal excluding lithium in the finally manufactured positive electrode active material.

[0219] Comparative Example 8

[0220] In the preparation of the positive active material, the positive active material and the coin-type half-cell were prepared in substantially the same manner as in Example 11, except that the second mixed solution was not sprayed into the mixer, and the mixer was heated to 450°C instead of 380°C to perform drying and coating simultaneously.

[0221] The aluminum content in the aluminum raw material and the tungsten content in the tungsten raw material used in the manufacture of the cathode active material according to the examples and comparative examples are shown in Table 1 below.

[0222]

[0223] Evaluation Example 1: Initial Charge / Discharge Capacity and Efficiency

[0224] The lithium secondary batteries prepared in the examples and comparative examples were charged at 25°C with a constant current of 0.2C to an upper voltage limit of 4.55V and with a constant voltage of 0.05C, and then discharged at 0.2C to a cutoff voltage of 3.0V to perform initial charge and discharge. Table 1 below shows the initial charge capacity, initial discharge capacity, and the ratio of the latter to the former calculated as efficiency.

[0225] Evaluation Example 2: -20℃ capacity

[0226] The lithium secondary batteries prepared in the examples and comparative examples were charged at 25°C with a constant current of 0.2C to an upper voltage limit of 4.25V and with a constant voltage of 0.05C, and then discharged at 0.2C to a cutoff voltage of 3.0V to perform initial charging and discharging. Additionally, after charging at 25°C with a constant current of 0.2C to an upper voltage limit of 4.25V and with a constant voltage of 0.05C, discharged at -20°C with 0.2C to a cutoff voltage of 3.0V, and the discharge capacity at this time is shown as the discharge capacity in Table 1 below.

[0227] Evaluation Example 3: High-temperature life

[0228] Following the initial charge and discharge of Evaluation Example 1, a cycle of charging at 1.0C and discharging at 1.0C was repeated 50 times or more in a voltage range of 3.0V to 4.55V at 45℃, and the ratio of the 50-cycle discharge capacity to the initial discharge capacity was calculated and shown as the lifespan in Table 1 below.

[0229] Evaluation Example 4: Dose Recovery Rate

[0230] The lithium secondary batteries prepared in the examples and comparative examples were subjected to one charge-discharge cycle at 0.3C, and the discharge capacity was measured. Subsequently, the obtained batteries were stored at a high temperature (45℃) for 7 days, and then subjected to one charge-discharge cycle at 0.3C to measure the discharge capacity. The ratio of the discharge capacity after 7 days of storage to the discharge capacity before high-temperature storage was calculated, and the results are shown as the capacity recovery rate in Table 1 below.

[0231] Evaluation Example 5: Energy Density

[0232] The lithium secondary batteries prepared in the examples and comparative examples were charged and discharged at 25°C with a rate limit of 0.2C / 0.2C in a voltage range of 3.0V to 4.45V to calculate the energy density, which is shown in Table 1 below. The energy density was calculated using the formula {(average driving voltage (V) x capacity (Ah)) / cell weight (kg)}, where the capacity was calculated by multiplying the positive electrode volume (cc) by the discharge capacity (Ah / cc).

[0233] Al (mol%) W (mol%) B (mol%) Initial Charge Capacity (mAh / g) Initial Discharge Capacity (mAh / g) Efficiency (%) Discharge Capacity (mAh / g) Lifetime (%) Capacity Recovery Rate (%) Energy Density (Wh / kg) Example 10. 20.025-232.5203.787.612291.586.2772 Example 20. 30.025-232.2203.687.712491.886.4772 Example 30. 40.025-232.0203.587.712392.587.2771 Example 40. 50.025-231.8202.887.512293.288.7769 Example 50.60.025-231.5202.187.312193.188.5766 Example 60.70.025-231.2201.687.211993.188.5764 Example 70.30.020.25232.2205.388.413692.888.5778 Example 80.30.020.5232.5206.588.813893.288.9782 Example 90.30.020.75232.4205.288.313893.088.8778 Example 100.30.021.0232.4204.387.913792.988.2774 Example 110.20.025-232.1201.586.812391.785.4764 Example 120.20.05-232.5203.487.512492.586.5771 Example 130.20.1-231.9201.887.012492.686.2765 Example 140.20.15-231.4200.686.712392.586.2760 Example 150.20.2-230.9199.586.412191.786.0756 Comparative Example 10.4--230.5196.585.212081.283.2745 Comparative Example 20.2--230.9196.985.311983.285.1746 Comparative Example 30.3--230.5196.285.111784.185.5743 Comparative Example 40.2--230.7197.085.411585.482.3748 Comparative Example 50.5--229.7195.685.211575.175.0741 Comparative Example 60.2--229.6194.584.911785.280.9739Comparison Example 71.0--229.1195.285.211480.981.2740Comparative Example 80.2--228.9192.183.910583.272.2741.

[0234] Referring to Table 1, in the case of Examples 1 to 6, in which aluminum nitrate hydrate is fed into a filter press during cleaning and drying and tungsten coating are performed simultaneously using a wet coating method while the mixer is operating after the cleaning process, it can be confirmed that the initial charge / discharge capacity, efficiency, capacity recovery rate, life characteristics, and energy density are superior compared to Comparative Example 1, in which an aluminum coating layer is formed through dry coating of the cleaned product; Comparative Examples 2 and 3, in which an aluminum coating layer is formed through wet coating; and Comparative Example 4, in which drying and coating are performed at a high temperature. In particular, according to Example 4, when the aluminum content in the aluminum nitrate hydrate is introduced in an amount of 0.5 mol% relative to 100 mol% of the total metal excluding lithium in the cathode active material, it can be confirmed that the efficiency, capacity, capacity recovery rate, life characteristics, and energy density are the best.

[0235] In addition, in the case of Examples 7 to 10, in which boron acid is introduced into a filter press during cleaning and drying and tungsten and aluminum coating are performed simultaneously using a wet coating method while the mixer is operating after the cleaning process, it can be confirmed that the initial charge / discharge capacity, efficiency, capacity recovery rate, lifespan characteristics, and energy density are superior compared to Comparative Example 1, in which an aluminum coating layer is formed through dry coating of the cleaned product; Comparative Examples 2 and 3, in which an aluminum coating layer is formed through wet coating; and Comparative Example 4, in which drying and coating are performed at a high temperature. In particular, according to Example 8, when the boron content in the boron acid is introduced in an amount of 0.5 mol% relative to 100 mol% of the total metal excluding lithium in the cathode active material, it can be confirmed that the efficiency, capacity, capacity recovery rate, lifespan characteristics, and energy density are the best.

[0236] In addition, in the case of Examples 11 to 15, in which aluminum nitrate hydrate is introduced into a filter press during cleaning and ammonium metatungsten hydrate is sprayed during the operation of a mixer after the cleaning process to simultaneously perform drying and coating, it can be confirmed that the initial charge / discharge capacity, efficiency, capacity recovery rate, life characteristics, and energy density are superior compared to Comparative Example 5, in which an aluminum coating layer is formed through dry coating of the cleaned product; Comparative Examples 6 and 7, in which an aluminum coating layer is formed wetly on the cleaned product but drying and the second heat treatment are performed as separate processes; and Comparative Example 8, in which drying and coating are performed at a high temperature. In particular, according to Example 12 or Example 13, when the tungsten content in the ammonium metatungsten hydrate is introduced in an amount of 0.05 mol% to 0.1 mol% relative to 100 mol% of the total metal excluding lithium in the cathode active material, it can be confirmed that the efficiency, capacity, capacity recovery rate, life characteristics, and energy density are the best.

[0237] Although preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concepts defined in the following claims are also included within the scope of the present invention.

[0238] [Explanation of the symbol]

[0239] 100: Lithium secondary battery 10: Positive electrode

[0240] 11: Positive lead tab 12: Positive terminal

[0241] 20: Cathode 21: Cathode lead tab

[0242] 22: Negative terminal 30: Separator

[0243] 40: Electrode assembly 50: Case

[0244] 60: Sealing member 70: Electrode tab

[0245] 71: Positive tab 72: Negative tab

Claims

1. (1) A step of preparing a core particle containing a layered lithium nickel-manganese-based composite oxide, in the form of a secondary particle, a single particle, or a combination thereof in which a plurality of primary particles are aggregated; (2) A step of cleaning the core particles by mixing one or more of aluminum raw materials and boron raw materials, the core particles, and cleaning water; (3) A step of obtaining a cleaned product by removing a portion of the cleaning water such that the cleaning water is included in an amount of 1% to 10% by weight relative to the total 100% by weight of the core particles and cleaning water; and (4) A step of introducing the above-mentioned cleaning product and tungsten raw material into a mixer and heat-treating at 300°C to 400°C; a method for manufacturing an anode active material.

2. In Paragraph 1, A method for manufacturing a positive electrode active material represented by the following chemical formula 2, wherein the above-mentioned layered lithium nickel-manganese-based composite oxide: [Chemical Formula 2] Li a2 Ni x2 Mr y2 Al z2 M 2 w2 O 2-b2 X b2 In Chemical Formula 2, 0.9≤a2≤1.8, 0.6≤x2≤0.8, 0.1≤y2≤0.4, 0≤z2≤0.03, 0≤w2≤0.3, 0.9≤x2+y2+z2+w2≤1.1, and 0≤b2≤0.1, and M 2 is one or more elements selected from B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zr, and Zn, and X is one or more elements selected from F, P, and S.

3. In Paragraph 1, A method for manufacturing a positive electrode active material in which the nickel content is 60 mol% to 80 mol% based on 100 mol% of the total metal excluding lithium in the above-mentioned layered lithium nickel-manganese composite oxide.

4. In Paragraph 1, A method for manufacturing an anode active material, wherein, in the step of cleaning the core particles, the core particles and cleaning water are mixed in a weight ratio of 0.5:1 to 1:

1.

5. In Paragraph 1, The above tungsten raw material is ammonium metatungsten hydrate (H 26 N6O 40 W 12 Method for manufacturing a positive electrode active material that is -H2O.

6. In Paragraph 1, In the above step (2), aluminum raw materials are mixed, A method for manufacturing a positive electrode active material in which the aluminum content in the aluminum raw material is 0.1 mol% to 1.0 mol% based on the total amount of aluminum in the aluminum raw material and the total amount of metal excluding lithium in the core particles, which is 100 mol%.

7. In Paragraph 1, In the above step (2), the boron raw material is mixed, A method for manufacturing an anode active material in which the boron content of the boron raw material is 0.1 mol% to 1.0 mol% based on the total metal excluding lithium in the core particles and the total boron of the boron raw material being 100 mol%.

8. In Paragraph 1, A method for manufacturing an anode active material in which the tungsten content of the tungsten raw material is 0.01 mol% to 0.5 mol% based on the total metal excluding lithium in the core particles and 100 mol% of the total tungsten of the tungsten raw material.

9. In Paragraph 1, The above mixer is a method for manufacturing a positive electrode active material by mixing at a speed of 50 RPM or less.

10. In Paragraph 1, A method for manufacturing an anode active material in step (4) above, wherein an aluminum raw material is further added to a mixer.

11. In Paragraph 1, After the above step (3), (3-2) A step of preparing a coating solution containing tungsten raw material by adding and mixing tungsten raw material into an aqueous solvent; further comprising, A method for manufacturing an anode active material, wherein in step (4) above, the tungsten raw material is fed into a mixer by spraying a coating solution containing the tungsten raw material into the mixer.

12. In Paragraph 1, A method for manufacturing a positive electrode active material in which the heat treatment temperature of step (4) above is 350℃ to 390℃.

13. A positive active material manufactured by a manufacturing method according to any one of paragraphs 1 to 12.

14. In Paragraph 13, The above-described positive electrode active material comprises a layered lithium nickel-manganese-based composite oxide and a core particle in the form of a secondary particle, a single particle, or a combination thereof formed by the aggregation of a plurality of primary particles; and A positive electrode active material comprising a coating layer located on the surface of the core particle and containing one or more of aluminum and boron and tungsten.

15. In Paragraph 14, The above coating layer contains aluminum, and A positive electrode active material having an aluminum content of 0.1 mol% to 1.0 mol% based on 100 mol% of total metal excluding lithium on the surface of the positive electrode active material, as measured by SEM-EDS on the surface of the positive electrode active material.

16. In Paragraph 14, The above coating layer contains tungsten, and A positive electrode active material having a tungsten content of 0.01 mol% to 0.1 mol% based on 100 mol% of total metal excluding lithium on the surface of the positive electrode active material, as measured by SEM-EDS on the surface of the positive electrode active material.

17. In Paragraph 14, The above coating layer contains boron, and A positive electrode active material having a boron content of 0.1 mol% to 1.0 mol% based on 100 mol% of the total metal excluding lithium on the surface of the positive electrode active material, as measured by SEM-EDS on the surface of the positive electrode active material.

18. In Paragraph 14, A positive active material having a coating layer thickness of 5 nm to 200 nm.

19. In Paragraph 14, The above coating layer is a positive active material in the form of a film that continuously surrounds the surface of the above single particle.

20. A positive electrode comprising a positive electrode active material according to paragraph 13; cathode; and A lithium secondary battery containing an electrolyte.

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