Positive electrode active material and method for manufacturing the same, positive electrode containing the same, and lithium secondary battery

Abstract

We propose a positive electrode active material that enables uniform particle growth during manufacturing, and a manufacturing method thereof, thereby proposing a lithium secondary battery with excellent charge / discharge efficiency and lifespan characteristics. [Solution] The positive electrode active material according to one embodiment contains a nickel content of 60 mol% or more relative to 100 mol% of the total metal excluding lithium, and includes a lithium nickel-based composite oxide containing zirconium, and is in single-particle form with a span value of 1.10 to 1.25.

Description

[Technical Field]

[0001] This disclosure relates to a positive electrode active material, a method for producing the same, a positive electrode containing the same, and a lithium secondary battery. [Background technology]

[0002] Recently, with the rapid proliferation of electronic devices that use batteries, such as mobile phones, laptops, and electric vehicles, the demand for rechargeable batteries with high energy density and high capacity has been rapidly increasing. As a result, research and development to improve the performance of lithium-ion rechargeable batteries is being actively pursued.

[0003] A lithium secondary battery is a battery comprising a positive electrode and a negative electrode containing an active material that allows for the insertion and deintercalation of lithium ions, and an electrolyte, which produces electrical energy through oxidation and reduction reactions that occur when lithium ions are inserted / deintercalated at the positive and negative electrodes.

[0004] To realize lithium secondary batteries that meet these applications, a variety of positive electrode active materials are being considered. Among them, lithium nickel oxides, lithium nickel manganese cobalt composite oxides, lithium nickel cobalt aluminum composite oxides, and lithium cobalt oxides are mainly used as positive electrode active materials. High-nickel positive electrode active materials with a nickel content of approximately 80 mol% or more can achieve high energy density and have been actively developed recently, but they have limitations due to various problems such as structural degradation due to charging and discharging, surface side reactions with the electrolyte, and degradation due to particle cracking. Therefore, there is a need for the development of positive electrode active materials that can achieve both high energy density and long life characteristics.

[0005] While secondary particle forms, consisting of aggregated primary particles, have generally been used as high-nickel cathode active materials to achieve high capacity, single-particle forms are currently being investigated to achieve longer lifespan and reduce gas generation. However, increasing the firing temperature to produce single particles increases the aggregation phenomenon between particles, leading to a decrease in productivity. Research has proposed adding alkaline grain growth accelerators during single-particle synthesis to eliminate interparticle aggregation and lower the firing temperature, but residual grain growth accelerators after firing act as resistance within the cathode, reducing lifespan. Furthermore, if a washing process is required to remove residual grain growth accelerators and salts, manufacturing costs increase and the process becomes more complex.

[0006] To solve this problem, a method was used in which an element (e.g., aluminum) that can substitute for the alkali-based grain growth promoter is doped when the positive electrode active material precursor and lithium raw material are mixed. However, there is a problem in that the element is not easily uniformly doped into the positive electrode active material. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Korean Published Patent No. 10-2023-0081051 [Overview of the project] [Problems that the invention aims to solve]

[0008] One embodiment proposes a method for manufacturing a positive electrode active material that enables uniform particle growth during production, thereby proposing a lithium secondary battery with excellent charge / discharge efficiency and lifespan characteristics. [Means for solving the problem]

[0009] One embodiment contains a lithium nickel composite oxide with a particle size distribution of 60 mol% or more nickel relative to 100 mol% of the total metal excluding lithium, and includes zirconium, with a span ((D90 -D 10 ) / D 50 The present invention provides a single-particle positive electrode active material with a value of 1.10 to 1.25.

[0010] In another embodiment, a method for producing a positive electrode active material is provided, which includes the steps of: mixing a zirconium raw material and a nickel raw material and performing a coprecipitation reaction to produce a nickel-based composite hydroxide containing zirconium; performing a primary heat treatment on the zirconium-containing nickel-based composite hydroxide to produce a nickel-based composite oxide containing zirconium; mixing the zirconium-containing nickel-based composite oxide with a lithium raw material and performing a secondary heat treatment to produce a lithium-nickel-based composite oxide containing zirconium in the form of secondary particles in which a plurality of primary particles have aggregated; and pulverizing the lithium-nickel-based composite oxide in the form of secondary particles to obtain a positive electrode active material in the form of single particles.

[0011] In another embodiment, a lithium secondary battery comprising the positive electrode, negative electrode, and electrolyte is provided. [Effects of the Invention]

[0012] One embodiment of the positive electrode active material allows for uniform particle growth during manufacturing, and lithium secondary batteries containing it have the advantage of excellent charge / discharge efficiency and lifespan characteristics. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic cross-sectional view showing a lithium secondary battery according to one embodiment. [Figure 2] This is a schematic cross-sectional view showing a lithium secondary battery according to one embodiment. [Figure 3] This is a schematic cross-sectional view showing a lithium secondary battery according to one embodiment. [Figure 4] This is a schematic cross-sectional view showing a lithium secondary battery according to one embodiment. [Figure 5] This is an SEM image of the cathode active material produced in Example 1. [Figure 6]This is an SEM image of the cathode active material produced in Comparative Example 1. [Figure 7] This is an SEM image of the cathode active material produced in Comparative Example 2. [Modes for carrying out the invention]

[0014] The following describes specific embodiments in detail so that they can be easily implemented by those with ordinary skill in the art. However, the present invention can be realized in various different forms and is not limited to the embodiments described herein.

[0015] The terms used herein are for illustrative purposes only and are not intended to limit the invention. Unless otherwise clearly indicated in the context, singular expressions include plural expressions.

[0016] Here, "these combinations" refers to mixtures of components, laminates, composites, copolymers, alloys, blends, reaction products, etc.

[0017] Here, terms such as “include,” “equip,” or “possess” are intended to specify the existence of the implemented features, figures, stages, components, or combinations thereof, and should be understood not to preemptively exclude the existence or possibility of adding one or more other features, figures, stages, components, or combinations thereof.

[0018] To clearly represent various layers and regions in the drawings, thicknesses are shown enlarged, and similar parts are given the same reference numerals throughout the specification. When a layer, film, region, plate, or other part is said to be "on top of" or "on" another part, this includes not only when it is "directly on top of" another part, but also when there is another part in between. Conversely, when a part is said to be "directly on top of" another part, it means that there is no other part in between.

[0019] Furthermore, the term "layer" here includes not only the shapes formed on the entire surface when observed in a plan view, but also the shapes formed on a part of the surface.

[0020] The average particle size can be measured by methods widely known to those skilled in the art, for example, by a particle size analyzer, or by transmission electron microscope images or scanning electron microscope images. Alternatively, it can be measured using dynamic light scattering, and the average particle size value can be calculated after counting the number of particles for each particle size range through data analysis. Unless otherwise defined, the average particle size is the diameter (D) of the particle whose cumulative volume in the particle size distribution is 50% by volume. 50 ) can mean. Also, unless otherwise defined, the average particle size is obtained by measuring the size (diameter or length of the long axis) of more than 20 random particles in a scanning electron microscope image to obtain a particle size distribution, and the diameter (D) of the particle whose cumulative volume in the said particle size distribution is 50% by volume. 50 This could be the average particle size taken from ).

[0021] Here, "or" is not interpreted as having an exclusive meaning; for example, "A or B" is interpreted as including A, B, A+B, etc.

[0022] The term "metal" is interpreted as a concept that includes general metals, transition metals, and metalloids.

[0023] positive electrode active material One embodiment provides a positive electrode active material that contains a lithium nickel composite oxide containing zirconium, with a nickel content of 60 mol% or more relative to 100 mol% of the total metal excluding lithium, and is in single-particle form with a span value of 1.10 to 1.25.

[0024] The aforementioned positive electrode active material has the advantage of being able to produce a uniformly grown single-particle positive electrode active material by uniformly distributing zirconium, which acts as a grain growth promoter during the synthesis process, within the positive electrode active material precursor, and by including this, it is possible to realize a lithium secondary battery with excellent charge / discharge efficiency and life characteristics.

[0025] Here, a single particle means a particle that does not have a grain boundary within the particle and exists alone, consisting of one particle, and can mean a single particle, a monolith structure or a single body structure or non-aggregated particles that exist as an independent phase in which the particles are not mutually aggregated morphologically. As an example, it may be a single crystal. The single particles may exist alone or the single particles may be aggregated with each other. For example, 2 to 9 single particles may be aggregated and in contact with each other.

[0026] In one embodiment, the single particles may exist alone or 5 or fewer single particles may be attached to each other.

[0027] As an example, the span value is an index indicating the width of the particle size distribution of the positive electrode active material and can be used to evaluate the uniformity of the positive electrode active material particles.

[0028] As an example, the span value can be measured through a particle size analyzer for the positive electrode active material, and using equipment such as a laser diffraction particle size analyzer or a dynamic light scattering analyzer, the particle sizes corresponding to 10%, 50%, and 90% cumulative volume in the particle size distribution are measured and can be calculated using these values.

[0029] As an example, the span value can be calculated by the formula {(D 90 -D 10 ) / D 50 )}. In the above formula, D 10 is the particle size indicating that 10% of the particles are smaller than this size in the particle size cumulative distribution curve, D 50 is the particle size indicating that 50% of the particles are smaller than this size in the particle size cumulative distribution curve, and D 90 is the particle size indicating that 90% of the particles are smaller than this size in the particle size cumulative distribution curve.

[0030] As an example, the span value of the positive electrode active material is 1.10 to 1.25, and may be, for example, 1.13 to 1.25, 1.10 to 1.24, 1.13 to 1.24, 1.15 to 1.23, 1.18 to 1.22, or 1.19 to 1.21.

[0031] As an example, the BET specific surface area value of the positive electrode active material is 0.75 m². 2 / g~1.2m 2 It can also be expressed as / g, for example, 0.8m 2 / g~1.2m 2 / g, or 0.9m 2 / g~1.1m 2 / g is also acceptable.

[0032] When the span value and BET specific surface area value of the positive electrode active material satisfy the aforementioned numerical range, the particle size distribution is uniform, making it possible to realize a positive electrode active material with excellent particle uniformity, and lithium secondary batteries containing it have the advantage of having very good charge / discharge characteristics and life characteristics.

[0033] As an example, the average particle size (D) of the positive electrode active material 50 The particle may be in a single-particle form with a size of 1 μm to 4 μm, for example, 1 μm to 3 μm, 2 μm to 4 μm, or 2 μm to 3 μm.

[0034] As an example, the positive electrode active material is D 10 The particles may be in single-particle form with a particle size of 0.1 μm to 3 μm, for example, 0.5 μm to 2.5 μm, or 1 μm to 2 μm.

[0035] As an example, the positive electrode active material is D 90 The particles may be in the form of single particles with a particle size of 3 μm to 6 μm, for example, 4 μm to 6 μm, or 4 μm to 5.5 μm.

[0036] As an example, the positive electrode active material is D 25 The particles may be in single-particle form with a particle size of 0.5 μm to 4 μm, for example, 1 μm to 3 μm, or 1.5 μm to 2.5 μm.

[0037] As an example, the positive electrode active material is D 75 The particles may be in single-particle form with a particle size of 2.5 μm to 5 μm, for example, 3 μm to 5 μm, or 3 μm to 4.5 μm.

[0038] In addition to the span value, if the particle size range of the single-particle positive electrode active material satisfies the aforementioned numerical range, a positive electrode active material with an even more uniform particle size distribution and superior particle uniformity can be realized.

[0039] Single particles satisfying the aforementioned particle size range are structurally stable, can increase the energy density of the positive electrode, and can improve the long-life characteristics of lithium secondary batteries. Here, the average particle size is, for example, obtained by measuring the size (particle size, major axis, or major axis length) of any 20 or more particles using scanning electron microscope images to obtain the particle size distribution, where the size of a particle whose cumulative volume is 50% by volume (D 50 This could be the result of calculating ( ).

[0040] The lithium nickel composite oxide containing zirconium can be described as a high-nickel oxide in which the nickel content is 60 mol% or more relative to 100 mol% of the total metal excluding lithium. The nickel content may be, for example, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more relative to 100 mol% of the total metal excluding lithium, or it may be 99 mol% or less, or 98 mol% or less. When the nickel content in the lithium nickel composite oxide satisfies the above range, high capacity and high energy density can be achieved.

[0041] The aforementioned lithium nickel-based composite oxide may contain a specific amount of zirconium as a dopant in addition to nickel.

[0042] As an example, the zirconium may be present in an amount of 0.1% to 0.4% by weight per 100% by weight of the lithium nickel-based composite oxide, for example, 0.1% to 0.3% by weight, 0.1% to 0.2% by weight, 0.15% to 0.2% by weight, or 0.16% to 0.18% by weight.

[0043] If the zirconium is present in an amount of less than 0.1% by weight relative to 100% by weight of the lithium nickel-based composite oxide, the positive electrode active material particles may not be uniform, and if it is present in an amount of more than 0.4% by weight, an excess of zirconium may be added, causing aggregation within the positive electrode active material.

[0044] As an example, the lithium nickel-based composite oxide containing zirconium may be represented by chemical formula 1. [Chemical formula 1] Li a1 Ni x1 M 1 y1 Zr z1 O 2-b1 X b1

[0045] In the above chemical formula 1, 0.9≦a1≦1.2, 0.6≦x1≦0.991, 0≦y1≦0.5, 0.001≦z1≦0.003, 0.9≦x1+y1≦1.1, and 0≦b1≦0.1, M 1 X is one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zn, and X is one or more elements selected from F, P, and S.

[0046] In the above chemical formula 1, 0.9≦a1≦1.1, 0.9≦a1≦1.05, or 0.9≦a1≦1 may also be true. Alternatively, 0.7≦x1≦0.991 and 0≦y1≦0.291, or 0.8≦x1≦0.991 and 0≦y1≦0.191, or 0.9≦x1≦0.991 and 0≦y1≦0.091. z1, which indicates the Zr content, may be, for example, 0.001≦z1≦0.002.

[0047] According to one embodiment, the zirconium concentration within the single particle can be uniform. For example, the single particle does not have a zirconium concentration gradient from the center toward the surface, nor is the zirconium concentration higher or lower closer to the surface than in the center of the single particle; rather, the zirconium is uniformly dispersed within the single particle. This structure can be said to be obtained by synthesizing a positive electrode active material in single particle form using a zirconium-containing precursor without additional zirconium doping during the single particle synthesis process. For example, this can be said to be a characteristic obtained by using a zirconium-containing nickel oxide as a precursor according to one embodiment, mixing this precursor with a lithium raw material, and heat-treating it to synthesize a lithium nickel-zirconium composite oxide. That is, the zirconium content within the single particle can be said to be the same or similar regardless of its position. For example, if the zirconium content is measured at any position in the cross-section of the single particle, it can be said that the zirconium content is the same, similar, or uniform regardless of whether the position is close to the center of the single particle or close to the surface of the single particle.

[0048] When zirconium is doped during the synthesis process of single particles, for example, when producing a lithium-nickel composite oxide doped with zirconium by mixing a nickel-containing precursor with a zirconium raw material and a lithium raw material and then calcining it, the zirconium does not distribute uniformly within the single particle and instead aggregates. On the other hand, in the positive electrode active material according to one embodiment, the zirconium is uniformly distributed within the single particle and does not aggregate, thereby improving the initial charge / discharge capacity, initial charge / discharge efficiency, and lifetime characteristics of the positive electrode active material. The uniform distribution of zirconium within a single particle can be ascertained, for example, by analyzing the distribution of the zirconium element through scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) on the cross-section of the single particle. That is, in the positive electrode active material according to one embodiment, zirconium is uniformly distributed as shown by SEM-EDS analysis of the cross-section of the single particle.

[0049] Method for manufacturing positive electrode active material One embodiment provides a method for producing a positive electrode active material, comprising the steps of: (1) mixing a zirconium raw material and a nickel raw material and performing a coprecipitation reaction to produce a nickel-based composite hydroxide containing zirconium; (2) performing a primary heat treatment on the zirconium-containing nickel-based composite hydroxide to produce a nickel-based composite oxide containing zirconium; (3) mixing the zirconium-containing nickel-based composite oxide with a lithium raw material and performing a secondary heat treatment to produce a lithium-nickel-based composite oxide containing zirconium in the form of secondary particles in which a plurality of primary particles have aggregated; and (4) pulverizing the lithium-nickel-based composite oxide in the form of secondary particles to obtain a positive electrode active material in the form of single particles.

[0050] Conventionally, when mixing nickel-based composite hydroxides / or oxides produced after a coprecipitation reaction with lithium raw materials and heat-treating them, a method was used in which zirconium raw materials were added together during the heat treatment. This existing method can be understood as a post-doping method with zirconium, and in this case, there was a problem in that the zirconium was not uniformly dispersed, resulting in the production of single-particle cathode active materials with uneven particle growth.

[0051] The manufacturing method according to one embodiment involves adding a zirconium raw material together with a nickel raw material and allowing a coprecipitation reaction to occur, which can be understood as a zirconium pre-doping method.

[0052] In this process, the zirconium raw material can act as both a dopant and a grain growth accelerator (flux). When the zirconium raw material is added, it promotes grain growth, making it possible to synthesize single particles effectively at a lower temperature compared to existing single-particle synthesis methods. This also suppresses particle aggregation and improves productivity. Since the zirconium raw material is used as a dopant for the cathode active material, it does not remain on the surface of the cathode active material particles, thereby improving its lifespan.

[0053] Furthermore, in one embodiment, by fabricating the positive electrode active material single crystal using a pre-doping method with zirconium, it is possible to produce a single crystal with a uniform distribution of zirconium and relatively uniform particle growth. In addition, lithium secondary batteries containing positive electrode active material single particles with uniform particle growth have the advantage of increased charge / discharge capacity and efficiency, as well as superior lifespan characteristics.

[0054] Furthermore, the above manufacturing method can be understood as a method of mixing and calcining a lithium raw material with a nickel-based composite oxide containing zirconium in oxide form (hereinafter, which can be referred to as "oxide precursor"). Conventionally, a method of mixing and calcining a lithium raw material with a nickel-based composite hydroxide in hydroxide form (hereinafter, which can be referred to as "hydroxide precursor") has been used. Since the oxide precursor has a smaller volume than the hydroxide precursor, the amount that enters the reactor (crucible, etc.) during the cathode active material manufacturing process is larger than that of the hydroxide precursor, which can further increase the reaction yield and be very advantageous in terms of production volume and economic aspects. In addition, since the oxide precursor has a similar reaction temperature range to the lithium raw material, it has the advantage that the cathode active material can grow more uniformly than when using a hydroxide precursor.

[0055] The following describes in detail the method for manufacturing the positive electrode active material.

[0056] A method for producing a positive electrode active material according to one embodiment includes the step of mixing a zirconium raw material and a nickel raw material and carrying out a coprecipitation reaction to produce a nickel-based composite hydroxide containing zirconium.

[0057] As an example, the zirconium raw material may include zirconium oxide, zirconium hydroxide, zirconium oxyhydroxide, zirconium sulfate, zirconium sulfide, zirconium acetate, zirconium nitrate, zirconium halide, or combinations thereof. Specific examples may include ZrO2, ZrO(NO3)2·xH2O (2≦x≦6), Zr(SO4)2·4H2O, or combinations thereof.

[0058] The nickel raw material may include nickel hydroxide, oxide, nitrogen oxide, sulfur oxide, carbon oxide, or a combination thereof.

[0059] As an example, in the aforementioned coprecipitation reaction, in addition to the zirconium raw material and the nickel raw material, a metal (M 1 The raw materials can be mixed together.

[0060] As an example, the aforementioned M 1 This may be one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zn.

[0061] As an example, the aforementioned metal (M 1 ) The raw material is the aforementioned M 1 This may include hydroxides, oxides, nitrogen oxides, sulfur oxides, carbon oxides, or combinations thereof that contain elements.

[0062] Complexing agents and pH adjusters can be used in the coprecipitation reaction. Complexing agents play a role in regulating the reaction rate of precipitate formation in the coprecipitation reaction and may include, for example, ammonium hydroxide (NH4OH), citric acid, or a combination thereof. The concentration of the complexing agent may be 0.1 to 1.5 M, for example, 0.1 to 1.4 M or 0.5 to 1.4 M. pH adjusters play a role in controlling the pH of the reactants and may include, for example, sodium hydroxide (NaOH), sodium carbonate (Na2CO3), sodium oxalate (Na2C2O4), or a combination thereof.

[0063] The coprecipitation reaction may include a first stage that reacts in a pH range of 11-12 and a second stage that reacts at a lower pH than the first stage. The pH of the first stage may be, for example, 11.5-12, 11.6-11.9, or 11.7-11.8, and can be considered a stomatal formation stage. The second stage reacts at an even lower pH than the first stage and can be considered a particle growth stage. The pH of the second stage may be, for example, 10-11.9, 10.5-11.7, 11-11.7, 11.2-11.6, or 11.3-11.6. The difference between the pH of the first stage and the pH of the second stage may be, for example, 0.1-1.5, or for example, 0.1-1.0, 0.1-0.8, 0.1-0.6, 0.1-0.5, 0.1-0.3, or 0.1-0.2.

[0064] The first stage can be performed for 6-12 hours, or 8-10 hours. The second stage can be performed for 10-30 hours, 15-25 hours, or 18-24 hours.

[0065] Next, the manufacturing method according to one embodiment includes the step of producing a nickel-based composite oxide containing zirconium by performing a primary heat treatment on the nickel-based composite hydroxide containing zirconium.

[0066] The aforementioned nickel-based composite oxide containing zirconium can be considered a precursor of the positive electrode active material, and can be referred to as a Zr pre-doping oxidation precursor. The aforementioned nickel-based composite oxide containing zirconium can be synthesized by primary heat treatment of the aforementioned nickel-based composite hydroxide containing zirconium produced in the coprecipitation reaction.

[0067] For example, the primary heat treatment temperature may be 500°C or lower, for example, 250°C to 500°C, 300°C to 500°C, 350°C to 500°C, or 400°C to 500°C, and for example, 400°C, 450°C, or 500°C.

[0068] For example, the primary heat treatment can be carried out in an oxygen or air atmosphere for 1 to 10 hours, or for example, 2 to 9 hours, or 4 to 8 hours.

[0069] The nickel-based composite oxide containing zirconium produced can be represented, for example, by chemical formula 11. [Chemical formula 11] Ni x11 M 1 y11 Zr z11 O2

[0070] In the above chemical formula 11, 0.6 ≤ x 11 ≤ 1, 0 ≤ y 11 < 0.4, 0 <Z11≦0.003 And 0.9 ≤ x 11 + y 11 + Z 11 ≤ 1.1, M 1 is one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zn.

[0071] In chemical formula 11, either 0.7≦x11≦1, 0≦y11≦0.3, 0.001≦Z11≦0.003, or 0.8≦x11≦1, 0≦y11≦0.2, 0.001≦Z11≦0.0025, or 0.9≦x11<1, 0 <y11≦0.1、0.001≦Z11≦0.002であってもよい。

[0072] As an example, the zirconium may be present in an amount of 0.1% to 0.5% by weight relative to 100% by weight of the nickel-based composite oxide containing zirconium, for example, 0.1% to 0.4% by weight, 0.1% to 0.3% by weight, 0.2% to 0.3% by weight, or 0.2% to 0.25% by weight.

[0073] If the zirconium content is less than 0.1% by weight relative to 100% by weight of the nickel-based composite oxide containing zirconium, it may be difficult to sufficiently promote the grain growth of single particles of the positive electrode active material. If the content exceeds 0.5% by weight, the zirconium may be added in excess, causing aggregation within the positive electrode active material.

[0074] For example, the span value of the nickel-based composite oxide containing zirconium may be 0.2 to 0.6, or for example, 0.3 to 0.6. When the span value of the precursor nickel-based composite oxide containing zirconium satisfies the above numerical range, the particle size distribution is uniform, and therefore the particle uniformity of the positive electrode active material produced using it is also excellent.

[0075] As an example, the tap density (TD) of the nickel-based composite oxide containing zirconium is 2 g / cm³. 3 ~3g / cm 3 It may be 2 g / cm³, for example. 3 ~2.5g / cm 3 , or 2.05 g / cm³ 3 ~2.2g / cm 3 This may also be the case. When the above numerical range is satisfied, a high reaction yield and uniform grain growth of the active material can be achieved.

[0076] As an example, the BET specific surface area of ​​the nickel-based composite oxide containing zirconium is 50 m². 2 / g~90m 2 It can also be / g, for example, 60m 2 / g~80m 2 / g, or 70m 2 / g~80m 2 It may also be / g. If the above numerical range is satisfied, the specific surface area of ​​the precursor is high, which can increase the reaction yield and achieve uniform grain growth of the active material.

[0077] A manufacturing method according to one embodiment includes the step of mixing the nickel-based composite oxide containing zirconium with a lithium raw material and subjecting it to a secondary heat treatment to produce a lithium-nickel-based composite oxide containing zirconium in the form of secondary particles in which a plurality of primary particles are aggregated.

[0078] As an example, the lithium raw material may include lithium hydroxide, lithium carbonate, lithium sulfate, lithium nitrate, or a combination thereof, and may also be, for example, anhydrous lithium hydroxide.

[0079] One embodiment of the manufacturing method has the advantage that, by doping a nickel-based composite oxide containing zirconium with zirconium using a pre-doping method, uniform grain growth of the active material can be promoted, and therefore, single particles can be effectively synthesized even when heat treatment is performed at a lower temperature compared to existing single-particle synthesis methods.

[0080] For example, the secondary heat treatment may be at 900°C or lower, or 890°C or lower, 850°C or lower, or 810°C or lower, and may be, for example, 600°C to 900°C, 600°C to 850°C, or 600°C to 800°C.

[0081] For example, the secondary heat treatment can be carried out in an oxidizing gas atmosphere, and for instance, the secondary heat treatment can be performed for 4 to 16 hours, 5 to 16 hours, or 6 to 16 hours.

[0082] In one embodiment of the method for producing a positive electrode active material, it is not necessary to add an alkaline grain growth accelerator or flux during the secondary heat treatment process of the nickel-based composite oxide containing zirconium and the lithium raw material. This prevents an increase in resistance due to residue after the secondary heat treatment, thereby improving the life characteristics of the lithium secondary battery, and since there is no need to add a step to remove the residue, process efficiency and cost-effectiveness can be improved.

[0083] Furthermore, as described above, in the method for producing a positive electrode active material according to one embodiment, the zirconium raw material can be added in advance during the synthesis process of the zirconium-containing nickel-based composite oxide before the process of secondary heat treatment of the zirconium-containing nickel-based composite oxide and the lithium raw material. As a result, zirconium is uniformly doped into the zirconium-containing nickel-based composite oxide, which is the precursor of the positive electrode active material, and the grain growth of the positive electrode active material single particles is promoted, thereby enabling the production of uniformly grown positive electrode active material particles.

[0084] Through the aforementioned secondary heat treatment, secondary particles containing a zirconium-containing lithium nickel composite oxide can be obtained. For example, the zirconium-containing lithium nickel composite oxide produced after the secondary heat treatment may contain secondary particles formed by the aggregation of multiple primary particles. In this case, the primary particles forming the secondary particles have grown sufficiently and become single crystals through the addition of zirconium raw materials.

[0085] The average particle size of the obtained secondary particles (D 50 The average particle size of secondary particles (D) may be 10 μm to 20 μm, for example, 10 μm to 18 μm, 12 μm to 16 μm, or 12 μm to 14 μm. 50 ) may have been measured through SEM imaging.

[0086] The average particle size (D) of the primary particles that make up the secondary particles 50 The average particle size of the primary particles (D) may be 1 μm to 4 μm, for example, 1 μm to 3 μm, 2 μm to 4 μm, or 2 μm to 3 μm. 50 This may have been measured through SEM imaging of the surface of secondary particles.

[0087] A manufacturing method according to one embodiment includes the step of pulverizing the lithium nickel-based composite oxide in secondary particle form to obtain a positive electrode active material in single particle form.

[0088] The aforementioned pulverization means breaking down the manufactured secondary particles, and can be understood as a process in which the primary particles that made up the secondary particles are separated from each other and become individual single particles. Through the pulverization process, the aforementioned average particle size (D 50 A positive electrode active material in single-particle form with a diameter of 1 μm to 4 μm can be obtained.

[0089] The aforementioned grinding can be performed using a jet mill device. When grinding with a jet mill, the bed weight can be set to 250 kg to 300 kg, the classification wheel rotation speed to 1500 rpm to 2000 rpm, the blower rotation speed to 2500 rpm to 3500 rpm, the pulse pressure to 0.25 bar to 0.75 bar, the gap pressure to 0.3 bar to 0.5 bar, and the G / A ratio to 6 to 8.

[0090] The grinding time can vary depending on the classification wheel rotation speed, blower rotation speed, pressure, and bed weight of the jet mill device. For example, based on the aforementioned jet mill device, it is possible to process 4 kg to 6 kg of sample per minute.

[0091] As an example, the single-particle positive electrode active material obtained may contain a compound represented by chemical formula 1, and the explanation of chemical formula 1 is as described above.

[0092] The zirconium may be present in an amount of 0.1% to 0.4% by weight per 100% by weight of the single-particle positive electrode active material, for example, 0.1% to 0.3% by weight, 0.1% to 0.2% by weight, 0.15% to 0.2% by weight, or 0.16% to 0.18% by weight. As an example, the zirconium content in the positive electrode active material can be measured using SEM (Scanning Electron Microscope)-EDS (Energy-Dispersive X-ray Spectroscopy) analysis technique.

[0093] A method for producing a positive electrode active material according to one embodiment may further include the step of mixing the obtained single-particle positive electrode active material with a coating material and performing a tertiary heat treatment. Through this step, it is possible to obtain single particles coated with a desired material.

[0094] The coating raw materials are not particularly limited and may be, for example, raw materials of one or more elements selected from Al, B, Co, Mg, V, Zn, and Zr, or hydroxides, oxides, sulfur oxides, nitrogen oxides, or carbon oxides containing the elements.

[0095] The aforementioned tertiary heat treatment can be carried out in an oxidizing gas atmosphere, for example, at 500°C to 900°C, or 600°C to 900°C, or 600°C to 800°C.

[0096] The aforementioned tertiary heat treatment can be carried out for 5 to 20 hours, for example, 7 to 20 hours or 10 to 20 hours.

[0097] The positive electrode active material obtained through the above manufacturing method contains a lithium nickel-based composite oxide, and the average particle size (D 50 This can include single particles with a diameter of 1 μm to 4 μm, and as an example, it can include a mixture of unground secondary particles and ground single particles.

[0098] positive electrode In one embodiment, a positive electrode for a lithium secondary battery is provided, comprising the positive electrode active material described above. For example, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector, the positive electrode active material layer may contain the positive electrode active material described above and may further contain a binder and / or conductive material.

[0099] For example, the positive electrode may further include an additive that can act as a sacrificial positive electrode.

[0100] Here, the positive electrode active material has a nickel content of 60 mol% or more relative to 100 mol% of the total metal excluding lithium, and contains a lithium nickel-based composite oxide containing zirconium, with a particle size distribution of span ((D 90 -D 10 ) / D 50 This is a single-particle form with a value of 1.10 to 1.25.

[0101] The content of the positive electrode active material may be 90% to 99.5% by weight relative to 100% by weight of the positive electrode active material layer, and the content of the binder and conductive material may be 0.5% to 5% by weight, respectively, relative to 100% by weight of the positive electrode active material layer.

[0102] The binder plays a role in ensuring that the positive electrode active material particles adhere well to each other and that the positive electrode active material adheres well to the current collector. Typical 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, and nylon.

[0103] The conductive material is used to impart conductivity to the electrodes, and any electronically conductive material that does not cause chemical changes in the battery can be used. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjenblack, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0104] Al can be used as the current collector, but is not limited to it.

[0105] Lithium-ion battery In one embodiment, a lithium secondary battery is provided, comprising the positive electrode, negative electrode, and electrolyte described above. As an example, the lithium secondary battery may include a positive electrode, a negative electrode, a separator located between the positive and negative electrodes, and an electrolyte.

[0106] Lithium-ion batteries are classified into cylindrical, prismatic, pouch-type, coin-type, and other types depending on their form. Figures 1 to 4 are schematic diagrams showing a lithium-ion battery according to one embodiment, where Figure 1 is cylindrical, Figure 2 is prismatic, and Figures 3 and 4 are pouch-type batteries. Referring to Figures 1 to 4, the lithium-ion battery 100 may include an electrode assembly 40 with 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, negative electrode 20, and separator 30 may be impregnated with an electrolyte (not shown). The lithium-ion battery 100 may include a sealing member 60 that seals the case 50, as shown in Figure 1. Also, in Figure 2, the lithium-ion battery 100 may include a positive electrode lead tap 11 and a positive electrode terminal 12, a negative electrode lead tap 21 and a negative electrode terminal 22. As shown in Figures 3 and 4, the lithium secondary battery 100 may include electrode taps 70, namely a positive electrode tap 71 and a negative electrode tap 72, which serve as electrical pathways for guiding the current formed in the electrode assembly 40 to the outside.

[0107] A lithium secondary battery according to one embodiment of the present invention can be applied to automobiles, mobile phones, and / or various forms of electrical devices, but the present invention is not limited thereto.

[0108] negative electrode The negative electrode may include a current collector and a negative electrode active material layer located on the current collector, the negative electrode active material layer including a negative electrode active material, and may further include a binder, a conductive material, or a combination thereof.

[0109] negative electrode active material The negative electrode active material includes a substance capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a substance that can be doped and dedoped with lithium, or a transition metal oxide.

[0110] The material capable of reversibly intercalating / deintercalating the lithium ions is a carbon-based anode active material, which may include, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, while examples of amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, and calcined coke.

[0111] As the 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 can be used.

[0112] As the substance capable of doping and undoping lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. As the Si-based negative electrode active material, silicon, a silicon-carbon composite, SiOx (0 < x ≦ 2), a Si-Q alloy (where Q is an element selected from alkali metals, alkaline earth metals, group 13 elements, group 14 elements (excluding Si), group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof, for example, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof), or a combination thereof may be used. As the Sn-based negative electrode active material, Sn, SnO2, a Sn alloy, or a combination thereof may be used.

[0113] The silicon-carbon composite may be a composite of silicon and amorphous carbon. The average particle size (D 50 ) of the silicon-carbon composite particles may be, for example, 0.5 μm to 20 μm. According to one embodiment, the silicon-carbon composite may be in a form in which silicon particles are coated with amorphous carbon on the surface of the silicon particles. For example, it may include secondary particles (cores) formed by granulating primary silicon particles, and an amorphous carbon coating layer (shell) located on the surface of the secondary particles. The amorphous carbon may also be located between the primary silicon particles, and for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed and present in an amorphous carbon matrix.

[0114] The silicon-carbon composite may further contain crystalline carbon. For example, the silicon-carbon composite may include a core containing 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, hard carbon, mesophase pitch carbide, and calcined coke.

[0115] When the silicon-carbon composite contains silicon and amorphous carbon, the content of silicon may be 10% to 50% by weight based on 100% by weight of the silicon-carbon composite, and the content of amorphous carbon may be 50% to 90% by weight. When the composite contains silicon, amorphous carbon, and crystalline carbon, the content of silicon may be 10% to 50% by weight based on 100% by weight of the silicon-carbon composite, the content of crystalline carbon may be 10% to 70% by weight, and the content of amorphous carbon may be 20% to 40% by weight.

[0116] Also, the thickness of the amorphous carbon coating layer may be 5 nm to 100 nm. The average particle diameter (D 50 ) of the silicon particles (primary particles) may be 10 nm to 1 μm, or 10 nm to 200 nm. The silicon particles may exist alone as silicon, or in the form of a silicon alloy, or in an oxidized form. The oxidized form of silicon can be represented as SiO x (0 < x ≤ 2). At this time, the atomic content ratio of Si:O indicating the degree of oxidation may be 99:1 to 33:67. In this specification, unless otherwise defined, the average particle diameter (D 50 ) means the diameter of the particle with a cumulative volume of 50% by volume in the particle size distribution.

[0117] The Si-based negative electrode active material or the Sn-based negative electrode active material can be used by mixing with a carbon-based negative electrode active material. When the Si-based negative electrode active material or the Sn-based negative electrode active material is mixed with the carbon-based negative electrode active material, the mixing ratio may be 1:99 to 90:10 by weight.

[0118] binder The binder plays a role in ensuring that the negative electrode active material particles adhere well to each other and that the negative electrode active material adheres well to the current collector. As the binder, a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof can 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, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0121] When an aqueous binder is used as the negative electrode binder, it may further contain a cellulosic compound that can impart viscosity. This cellulosic compound can be a mixture of one or more carboxymethylcellulose, hydroxypropylmethylcellulose, methylcellulose, or alkali metal salts thereof. The alkali metal can be Na, K, or Li.

[0122] The dry binder is a polymeric substance that can be formed into fibers, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0123] conductive material Conductive materials are used to impart conductivity to electrodes, and any electronically conductive material that does not cause chemical changes in the battery that is constructed can be used. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjenblack, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials in the form of metal powders or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0124] The content of the negative electrode active material may be 95% to 99.5% by weight relative 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 relative 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.

[0125] Current collector The negative electrode current collector may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or alloys thereof, and may be in the form of foil, sheet, or foam. The thickness of the negative electrode current collector may be, for example, 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0126] electrolyte The electrolyte for lithium secondary batteries may be, for example, an electrolyte solution, which may contain a non-aqueous organic solvent and a lithium salt.

[0127] Non-aqueous organic solvents serve as a medium through which ions involved in the electrochemical reactions of the battery can move. Non-aqueous organic solvents may be carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvents, aprotic solvents, or combinations thereof.

[0128] Examples of carbonate-based solvents that can be used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). Examples of ester-based solvents that can be used include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, and caprolactone. As ether-based solvents, dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran can be used. As ketone-based solvents, cyclohexanone can be used. As alcohol-based solvents, ethyl alcohol and isopropyl alcohol can be used, and as aprotic solvents, nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group with 2 to 20 carbon atoms, and can include double bonds, aromatic rings, or ether groups); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes can be used.

[0129] Non-aqueous organic solvents can be used alone or in combination of two or more. When using a mixture of two or more, the mixing ratio can be appropriately adjusted according to the desired battery performance, which should be widely understood by those working in this field.

[0130] When using carbonate-based solvents, cyclic carbonates and linear carbonates can be mixed, and the cyclic carbonates and linear carbonates can be mixed in a volume ratio of 1:1 to 1:9.

[0131] The non-aqueous organic solvent may further contain an aromatic hydrocarbon organic solvent. For example, the carbonate solvent and the aromatic hydrocarbon organic solvent can be mixed and used in a volume ratio of 1:1 to 30:1.

[0132] The electrolyte may further contain vinyl ethyl carbonate, vinylene carbonate, or ethylene carbonate compounds to improve battery life.

[0133] Typical examples of the aforementioned ethylene carbonate compounds include fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, and cyanoethylene carbonate.

[0134] Lithium salts are substances that dissolve in organic solvents and act as a source of lithium ions in batteries, enabling the operation of basic lithium secondary batteries and facilitating the movement of lithium ions between the positive and negative electrodes. Typical examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide; LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F2y+1 It may contain one or more selected from SO2) (where x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFBOF), and lithium bis(oxalato)borate (LiBOB).

[0135] It is preferable to use lithium salts within a concentration range of 0.1 M to 2.0 M. When the lithium salt concentration falls within this range, the electrolyte has appropriate ionic conductivity and viscosity, resulting in excellent performance and effective lithium ion movement.

[0136] Separator Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. Such separators can be made of polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more layers of these materials. Mixed multilayer films such as polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, and polypropylene / polyethylene / polypropylene three-layer separators can also be used.

[0137] The separator may include a porous substrate and a coating layer comprising organic, inorganic, or a combination thereof located on one or both sides of the porous substrate.

[0138] The porous substrate may be a polymer film formed from any one polymer selected from polyethylene, polyolefins such as 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, glass fiber, and polytetrafluoroethylene (e.g., Teflon®), or from a copolymer or mixture of two or more of these polymers.

[0139] The porous substrate can have a thickness of approximately 1 μm to 40 μm, for example, 1 μm to 30 μm, 1 μm to 20 μm, 5 μm to 15 μm, or 10 μm to 15 μm.

[0140] The 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)acrylamide sulfonic acid or a salt thereof.

[0141] The inorganic material may include, but is not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof. The average particle size (D 50 The wavelength can be 1 nm to 2000 nm, for example, 100 nm to 1000 nm or 100 nm to 700 nm.

[0142] The organic and inorganic materials may exist mixed in a single coating layer, or they may exist in a form in which a coating layer containing organic materials and a coating layer containing inorganic materials are laminated together.

[0143] 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.

[0144] Examples and comparative examples of the present invention are described below. However, the following examples are merely illustrative of the present invention, and the present invention is not limited to the following examples. [Examples]

[0145] Example 1 1. Manufacturing of positive electrode active material (1) Production of nickel-based composite oxides containing zirconium First, a nickel-based composite oxide containing zirconium was produced through the following coprecipitation method.

[0146] Nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved in distilled water, the solvent, in a molar ratio of Ni:Co:Mn = 95:4:1. This mixture was then mixed with Zr(SO4)2·4H2O, the zirconium raw material, to prepare a mixed metal raw material solution.

[0147] A diluted solution of aqueous ammonia (NH4OH) was prepared as a complexing agent, and sodium hydroxide (NaOH) was prepared as a pH adjuster. The concentration of the aqueous ammonia was 10% by weight, and the concentration of the sodium hydroxide was 20% by weight. The prepared mixed metal raw material solution, aqueous ammonia, and sodium hydroxide were added to the reactor, respectively.

[0148] After stirring the reactor for 10 hours with a pH of 11.75 (first stage), the pH was lowered to 11.55 and stirred for 22 hours (second stage) to create a difference in synthesis rates between the inside and outside of the particles, thereby synthesizing a nickel-based composite hydroxide containing zirconium.

[0149] Subsequently, the nickel-based composite hydroxide containing zirconium was subjected to primary heat treatment at 400°C for 6 hours in an oxygen atmosphere to produce a nickel-based composite oxide containing zirconium (hereinafter referred to as "Zr-pre-doped oxidation precursor").

[0150] (2) Manufacturing of positive electrode active material The prepared zirconium-containing nickel composite oxide and anhydrous lithium hydroxide were mixed, and the mixture was subjected to secondary heat treatment at 660°C for 12 hours in an oxygen atmosphere. The lithium nickel composite oxide containing zirconium produced after calcination had a composition of Li 1.00 Ni 0.93 Co 0.06 Mn 0.01 Zr 0.002 It was identified as O2 and was confirmed to be in a secondary particle form.

[0151] Subsequently, the lithium nickel composite oxide containing zirconium in secondary particle form is pulverized in a jet mill (processing 5 kg per minute) with a bed weight of 300 kg, a classification wheel rotation speed of 1740 rpm, a blower rotation speed of 3000 rpm, a pulse pressure of 0.5 bar, a gap pressure of 0.4 barm, and a G / A ratio of 6.3 to obtain single-particle form cathode active material (Li 1.00 Ni 0.93 Co 0.06 Mn 0.01 Zr 0.002 O2 was obtained.

[0152] The average particle size (D) of the obtained single-particle form of the positive electrode active material 50 ) is 2.5 μm, D 10 The particle size is 1.47 μm, D 90 The particle size is 4.87 μm, D 25 The particle size is 1.91 μm, and D 75 The particle size was 3.73 μm.

[0153] Furthermore, measurements using ICP-OES (Inductively Coupled Plasma Spectroscopy) revealed that Zr was present at a concentration of 0.18% by weight per 100% by weight of the obtained single-particle positive electrode active material.

[0154] 2. Manufacturing of lithium-ion batteries A cathode active material layer slurry was prepared by mixing 98.5% by weight of the manufactured cathode active material, 1.0% by weight of polyvinylidene fluoride binder, and 0.5% by weight of carbon nanotube conductive material. This slurry was then coated onto an aluminum foil current collector, dried, and rolled to produce a cathode. The manufactured cathode contains the cathode active material in the form of pulverized single particles.

[0155] A negative electrode active material slurry was prepared by mixing 97.5% by weight of graphite negative electrode active material, 1.5% by weight of carboxymethylcellulose, and 1% by weight of styrene-butadiene rubber in an aqueous solvent. The negative electrode was prepared by coating a copper foil current collector with the negative electrode active material slurry, drying, and rolling.

[0156] A lithium secondary battery was manufactured using a conventional method with a polytetrafluoroethylene separator and an electrolyte solution prepared by dissolving 1M LiPF6 in a solvent containing a 3:7 volume ratio mixture of ethylene carbonate and dimethyl carbonate.

[0157] Comparative Example 1 A nickel-based composite hydroxide containing zirconium, produced in the positive electrode active material manufacturing process of Example 1, was prepared, and the nickel-based composite hydroxide containing zirconium (hereinafter referred to as "Zr pre-doped hydroxide precursor") was mixed with anhydrous lithium hydroxide. Subsequently, the mixture was heat-treated in the same manner as the secondary heat treatment in Example 1. Furthermore, the positive electrode active material and lithium secondary battery according to Comparative Example 1 were manufactured using the same method as in Example 1 for all processes after the secondary heat treatment.

[0158] Comparative Example 2 1. Manufacturing of positive electrode active material A nickel-based composite hydroxide was synthesized using the same coprecipitation method as in Example 1, except that nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved in distilled water as a solvent to prepare a metal raw material mixed solution so that the molar ratio of Ni:Co:Mn was 95:4:1 (not mixed with ZrO2 as a zirconium raw material substance).

[0159] Thereafter, the nickel-based composite hydroxide was heat-treated at 400 °C for 6 hours in an oxygen atmosphere to produce a nickel-based composite oxide.

[0160] The prepared nickel-based composite oxide (hereinafter, which can be referred to as "Zr-undoped oxidation precursor"), anhydrous lithium hydroxide, and ZrO2 were mixed, and the mixture was heat-treated in the same manner as the secondary heat treatment in Example 1 to produce a Zr-post-doped oxidation precursor.

[0161] Also, the processes after the secondary heat treatment were all carried out in the same manner as in Example 1 to produce a positive electrode active material and a lithium secondary battery according to Comparative Example 2.

[0162] (Evaluation Example) Evaluation Example 1: Physical property evaluation of Zr doping precursors For the Zr-pre-doped oxidation precursor produced in Example 1, the Zr-pre-doped hydroxide precursor produced in Comparative Example 1, and the Zr-undoped oxidation precursor produced in Comparative Example 2, the span value, tap density (g / cm 3 ), BET (m 2 / g), and Zr content (ppm) were measured and shown in Table 1 below.

[0163] Specifically, for each of the above precursors, the particle sizes D 10 , D 50 , and D 90 corresponding to the 10%, 50%, and 90% cumulative values of the particle size distribution were measured, and using this, the span value was derived by calculating the formula {(D 90 -D 10 ) / D 50 .

[0164] Furthermore, each of the aforementioned precursor powders is tapped according to the ASTM B527 standard, the volume of the tapped powder is measured, and the tap density (g / cm³) is calculated by dividing the mass of the powder by the volume of the tapped powder. 3 ) was measured.

[0165] Furthermore, the BET specific surface area of ​​each of the aforementioned precursors was measured using a BET analyzer.

[0166] Furthermore, the Zr content of the Zr-first doped oxidation precursor of Example 1 and the Zr-first doped hydroxylation precursor of Comparative Example 1 was measured using ICP-OES (inductively coupled plasma spectroscopy).

[0167] [Table 1]

[0168] Referring to Table 1, it can be seen that the span value of the Zr pre-doped oxidation precursor produced in Example 1 is lower than that of the precursors in Comparative Examples 1 and 2, indicating a more uniform precursor particle size distribution.

[0169] Furthermore, the tapping density of the Zr-doped oxidation precursor produced in Example 1 is higher than that of the precursors in Comparative Examples 1 and 2. Therefore, the volume after tapping for the same mass is smaller, and it can be confirmed that the reaction yield is even higher than that of the comparative examples' precursors.

[0170] Furthermore, the BET specific surface area value of the Zr pre-doped oxidation precursor produced in Example 1 is significantly higher than that of the precursors in Comparative Examples 1 and 2. This confirms that the size of the precursor particles (or powder) is uniform and that their specific surface area is also very high.

[0171] Evaluation Example 2: SPAN value and BET value evaluation (uniformity check) The span values ​​were measured for the positive electrode active materials produced in Example 1, Comparative Example 1, and Comparative Example 2. Specifically, for each positive electrode active material, the D values ​​were measured for the particle sizes corresponding to the 10%, 50%, and 90% cumulative values ​​of the particle size distribution. 10 , D50 and D 90 were measured, and using this, the formula {(D 90 - D 10 ) / D 50} was calculated to derive the span value, which is shown in Table 2 below.

[0172] Also, the BET specific surface area of the positive electrode active materials produced in Example 1, Comparative Example 1, and Comparative Example 2 was measured using a BET analyzer and is shown in Table 2 below.

[0173] Evaluation Example 3: SEM Image Evaluation (Uniformity Check) SEM images of the positive electrode active materials produced in Example 1, Comparative Example 1, and Comparative Example 2 are shown in FIGS. 5, 6, and 7, respectively.

[0174] Referring to FIGS. 5, 6, and 7, in the case of Example 1, it can be confirmed that the grain growth of the single particles of the positive electrode active material was promoted by zirconium pre-doping synthesis and the particles grew uniformly. On the other hand, in the cases of Comparative Example 1 and Comparative Example 2, it can be confirmed that the particle uniformity is inferior to that of Example 1.

[0175] Evaluation Example 4: Evaluation of Initial Charge / Discharge Efficiency and Lifetime Characteristics The initial charge-discharge efficiency of the lithium secondary batteries produced in Example 1, Comparative Example 1, and Comparative Example 2 was evaluated.

[0176] Specifically, each lithium secondary battery was charged at a constant current of 0.2C to 4.3V and then at a constant voltage to 0.05C at 25°C, and then discharged at 0.2C to 3.0V to perform initial charge and discharge. The charge capacity (mAh), discharge capacity (mAh), and charge-discharge efficiency (%) at this time were measured and are shown in Table 2 below.

[0177] Next, a cycle of charging and discharging at 1.0C in the voltage range of 3.0V to 4.3V at 45°C was repeated 50 times. The capacity retention rate at this time was measured as the life (%) and is shown in Table 2 below.

[0178]

Table 2

[0179] Referring to Table 2, the positive electrode active material of Example 1 has a lower span value and a higher BET specific surface area value compared to the positive electrode active materials of Comparative Examples 1 and 2, confirming that the particle size grew uniformly.

[0180] Furthermore, it can be confirmed that the lithium secondary battery manufactured in Example 1 exhibits significantly superior initial charge / discharge efficiency and lifespan characteristics compared to the lithium secondary batteries manufactured in Comparative Examples 1 and 2.

[0181] While preferred embodiments of the present invention have been described above, the present invention is not limited thereto. It can be implemented in various ways within the scope of the claims, the detailed description of the invention, and the attached drawings, and these variations naturally also fall within the scope of the present invention. [Explanation of symbols]

[0182] 100: Lithium-ion rechargeable battery 10: Positive electrode 11: Positive lead tap 12: Positive terminal 20: Negative electrode 21: Negative lead tap 22: Negative terminal 30: Separator 40: Electrode assembly 50: Case 60: Sealing member 70: Electrode Tap 71: Positive Tap 72: Negative electrode tap

Claims

1. The nickel content is 60 mol% or more relative to 100 mol% of the total metal excluding lithium, and it contains a lithium nickel-based composite oxide containing zirconium. Particle size distribution span ((D 90 -D 10 ) / D 50 A positive electrode active material in single-particle form with a value of 1.10 to 1.

25.

2. The average particle size (D) of the positive electrode active material 50 The positive electrode active material according to claim 1, wherein the diameter is 1 μm to 4 μm.

3. The positive electrode active material according to claim 1, wherein the zirconium is contained in an amount of 0.1% to 0.4% by weight per 100% by weight of the lithium nickel-based composite oxide.

4. The positive electrode active material according to claim 1, wherein the lithium nickel-based composite oxide is represented by chemical formula 1. [Chemical formula 1] Li a1 N x1 M 1 y1 Zhr z1 O 2-b1 X b1 (In the above chemical formula 1, 0.9 ≤ a1 ≤ 1.2, 0.6 ≤ x1 ≤ 0.991, 0 ≤ y1 ≤ 0.5, 0.001 ≤ z1 ≤ 0.003, 0.9 ≤ x1 + y1 ≤ 1.1, and 0 ≤ b1 ≤ 0.1, M 1 (where X is one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zn, and X is one or more elements selected from F, P, and S.)

5. Positive electrode current collector, and A positive electrode active material layer located on the positive electrode current collector and containing the positive electrode active material described in any one of claims 1 to 4. The positive electrode, including the positive electrode.

6. A step in which zirconium and nickel raw materials are mixed and a coprecipitation reaction is carried out to produce a nickel-based composite hydroxide containing zirconium; A step of producing a nickel-based composite oxide containing zirconium by performing a primary heat treatment on the aforementioned nickel-based composite hydroxide containing zirconium; A step of mixing the zirconium-containing nickel-based composite oxide with a lithium raw material and subjecting it to a secondary heat treatment to produce a lithium-nickel-based composite oxide containing zirconium in the form of secondary particles in which multiple primary particles are aggregated; and The step of grinding the lithium nickel-based composite oxide in secondary particle form to obtain a cathode active material in single particle form. A method for producing a positive electrode active material, including the active material.

7. The method for producing a positive electrode active material according to claim 6, wherein the zirconium raw material includes zirconium oxide, zirconium hydroxide, zirconium oxyhydroxide, zirconium sulfate, zirconium sulfide, zirconium acetate, zirconium nitrate, zirconium halide, or a combination thereof.

8. In the aforementioned coprecipitation reaction, in addition to the zirconium raw material and the nickel raw material, a metal (M 1 ) Mix the raw materials together, Said M 1 The method for producing a positive electrode active material according to claim 6, wherein is one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zn.

9. The primary heat treatment temperature is 250°C to 500°C. The method for producing a positive electrode active material according to claim 6, wherein the primary heat treatment is performed in an oxygen atmosphere or an air atmosphere for 1 to 10 hours.

10. The method for producing a positive electrode active material according to claim 6, wherein the nickel-based composite oxide containing zirconium is represented by chemical formula 11. [Chemical formula 11] Ni x11 M 1 y11 Zr z11 O 2 (In the above chemical formula 11, 0.6 ≤ x¹¹ ≤ 1, 0 ≤ y¹¹ < 0.4, 0 < Z¹¹ ≤ 0.003, And 0.9 ≤ x¹¹ + y¹¹ + Z¹¹ ≤ 1.1, M 1 (It is one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zn.)

11. The method for producing a positive electrode active material according to claim 6, wherein the zirconium is contained in an amount of 0.1% to 0.5% by weight relative to 100% by weight of the nickel-based composite oxide containing the zirconium.

12. The secondary heat treatment temperature is 600°C to 900°C. The method for producing a positive electrode active material according to claim 6, wherein the secondary heat treatment is performed for 4 to 16 hours.

13. A method for producing a positive electrode active material according to claim 6, wherein no alkaline grain growth promoter is added during the secondary heat treatment process of the nickel-based composite oxide containing zirconium and the lithium raw material.

14. The average particle size (D) of the secondary particles 50 ) is 10 μm to 20 μm, The average particle size (D) of the primary particles that make up the secondary particles 50 The method for producing a positive electrode active material according to claim 6, wherein the thickness of the material is 1 μm to 4 μm.

15. The aforementioned grinding is performed using a jet mill device. The method for producing a positive electrode active material according to claim 6, wherein the rotation speed of the classification wheel of the jet mill device is 1500 rpm to 2000 rpm, the rotation speed of the blower is 2500 rpm to 3500 rpm, and the pulse pressure is 0.25 bar to 0.75 bar.

16. The average particle size (D) of the positive electrode active material in single-particle form. 50 The method for producing a positive electrode active material according to claim 6, wherein the particle size is 1 μm to 4 μm, and the zirconium is contained in an amount of 0.1% to 0.4% by weight per 100% by weight of the positive electrode active material in single particle form.

17. The positive electrode according to claim 5, Negative electrode, and electrolyte Lithium-ion secondary batteries, including lithium-ion batteries.

Images