A positive electrode active material precursor, a method for producing the same, and a method for producing a positive electrode active material containing the same.

Abstract

The present invention provides a cathode active material precursor capable of achieving high density, high capacity, long lifespan, and high energy density, a method for producing the same, and a method for producing a cathode active material containing the same. [Solution] A method for producing a positive electrode active material precursor in single particle form is provided, comprising the steps of (a) mixing a nickel-based hydroxide and an inert lithium salt to produce a mixture, and (b) subjecting the mixture to a first heat treatment to obtain a nickel-based oxide in single particle form. A positive electrode active material precursor and a method for producing the same according to one embodiment, and a method for producing a positive electrode active material containing the same, minimize the production process, ensure long life characteristics, and improve high-temperature storage characteristics. A lithium secondary battery to which the positive electrode active material is applied can exhibit high initial charge / discharge capacity and efficiency, and can achieve long life characteristics.

Description

[Technical Field]

[0001] This invention relates to a positive electrode active material precursor, a method for producing the same, and a method for producing a positive electrode active material containing the same. [Background technology]

[0002] Lithium-ion batteries, which offer high energy density while remaining portable, are primarily used as power sources for mobile information terminals such as mobile phones, laptops, and smartphones. Recently, research has been actively conducted on using high-energy-density lithium-ion batteries as power sources or energy storage sources for hybrid and electric vehicles.

[0003] To realize lithium secondary batteries that meet these applications, a variety of cathode active materials are being investigated. In recent years, with the rapidly increasing demand for large, high-capacity, or high-energy-density lithium secondary batteries, there is a need to develop cathode active materials and cathode active material precursors that can increase capacity while ensuring stability and enabling operation at high voltages. [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention provides a cathode active material precursor that can achieve high density, high capacity, long lifespan, and high energy density, a method for producing the same, and a method for producing a cathode active material containing the same. [Means for solving the problem]

[0005] One embodiment of the present invention provides a method for producing a positive electrode active material precursor in single-particle form, comprising the steps of (a) mixing a nickel-based hydroxide and an inert lithium salt to produce a mixture; and (b) subjecting the mixture to a first heat treatment to obtain a nickel-based oxide in single-particle form.

[0006] In another embodiment, a positive electrode active material precursor containing nickel-based oxide in a single particle form and having a span value according to the following formula 1 of 0.85 to 1.48 is provided. [Formula 1] Span = (D90 - D10) / D50

[0007] In Formula 1, D10 represents the particle size of particles having a cumulative volume of 10% by volume in the particle size distribution, D50 represents the particle size of particles having a cumulative volume of 50% by volume in the particle size distribution, and D90 represents the particle size of particles having a cumulative volume of 90% by volume in the particle size distribution.

[0008] In another embodiment, a method for manufacturing a positive electrode active material is provided, which includes a step of mixing the positive electrode active material precursor manufactured by the above manufacturing method with a lithium raw material and performing a second heat treatment.

[0009] In another embodiment, a method for manufacturing a positive electrode active material is provided, which includes a step of mixing the positive electrode active material precursor with a lithium raw material and performing a second heat treatment.

Advantages of the Invention

[0010] The positive electrode active material precursor, the method for manufacturing the same, and the method for manufacturing the positive electrode active material including the same according to an embodiment of the present invention minimize the production process, ensure long-life characteristics, and improve high-temperature storage characteristics. The lithium secondary battery applying the positive electrode active material can exhibit high initial charge and discharge capacity and efficiency, and can realize long-life characteristics.

Brief Description of the Drawings

[0011] [Figure 1] It is a diagram schematically showing a lithium secondary battery according to an embodiment. [Figure 2] It is a diagram schematically showing a lithium secondary battery according to an embodiment. [Figure 3] It is a diagram schematically showing a lithium secondary battery according to an embodiment. [Figure 4] It is a diagram schematically showing a lithium secondary battery according to an embodiment. [Figure 5]This graph shows the results of X-ray diffraction (XRD) analysis of the positive electrode active material precursor according to the examples. [Figure 6] This graph shows the results of X-ray diffraction (XRD) analysis of the positive electrode active material precursor according to Comparative Example 1. [Figure 7] This is an SEM image of the surface of the cathode active material precursor produced by Example 1. [Figure 8] This is an SEM image of the surface of the cathode active material precursor produced by Example 2. [Figure 9] This is an SEM image of the surface of the cathode active material precursor produced by Example 3. [Figure 10] This is an SEM image of the surface of the cathode active material precursor produced by Example 4. [Figure 11] This is an SEM image of the surface of the cathode active material precursor produced according to Example 5. [Figure 12] This is an SEM image of the surface of the cathode active material precursor produced by Example 6. [Figure 13] This is an SEM image of the surface of the cathode active material precursor produced by Comparative Example 1. [Figure 14] This is an SEM image of the surface of the positive electrode active material produced according to Example 1. [Figure 15] This is an SEM image of the surface of the positive electrode active material produced by Comparative Example 1. [Figure 16] This is an SEM image of the surface of the positive electrode active material produced by Comparative Example 2. [Figure 17] This graph shows the results of Raman spectroscopy (RAMAN) analysis of the inert lithium salt recovered after the production of the cathode active material precursor according to the examples. [Modes for carrying out the invention]

[0012] 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.

[0013] The terms used herein are for illustrative purposes only and are not intended to limit the invention. Unless otherwise clearly stated in the context, singular expressions include plural expressions.

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

[0015] Here, terms such as “include,” “equip,” or “possess” are intended to specify the existence of a particular feature, number, stage, component, or combination thereof, and should be understood not to preemptively exclude the existence or possibility of adding one or more other features, numbers, stages, components, or combinations thereof.

[0016] To clearly represent various layers and regions in the drawings, thicknesses are shown enlarged, and similar parts are given the same drawing 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.

[0017] 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 portion of the surface.

[0018] 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 after performing data analysis to count the number of particles for each particle size range, the average particle size value can be calculated from this. 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 ) means. Also, 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, obtained by measuring the size (diameter or length of the long axis) of more than 20 random particles from a scanning electron microscope image. 50 This could be the average particle size taken from ).

[0019] Here, "or" is not interpreted in an exclusive sense; for example, "A or B" is interpreted as including A, B, A+B, etc.

[0020] The term "metal" is interpreted as a concept that includes general metals, transition metals, and metalloids (metallic semi-metals).

[0021] Method for manufacturing a positive electrode active material precursor A method for producing a positive electrode active material precursor according to one embodiment comprises the steps of (a) mixing a nickel-based hydroxide and an inert lithium salt to produce a mixture; and (b) subjecting the mixture to a first heat treatment to obtain a nickel-based oxide in single-particle form, characterized in that the positive electrode active material precursor produced thereby is in single-particle form.

[0022] Nickel-based cathode active materials generally have a secondary particle shape in which multiple primary particles are aggregated. However, during prolonged use, volume changes in the particles that occur during continuous charging / discharging lead to crack formation within the secondary particles. These cracks facilitate the penetration of the electrolyte, accelerating side reactions and causing rapid performance degradation. To overcome this, it is necessary to control the shape of the nickel-based cathode active material as a single particle, thereby improving battery performance.

[0023] Generally, single-particle cathode active materials are synthesized by mixing a precursor with a lithium raw material, but this is mainly done at high temperatures to increase particle size. However, high temperatures cause particle clumping, limiting the synthesis of highly crystalline cathode active materials. Furthermore, additional grinding operations such as ball milling are required to ensure the dispersibility of cathode active material particles, resulting in a complex process with multiple steps.

[0024] Therefore, by first synthesizing a single-particle positive electrode active material precursor that does not contain lithium raw materials using a nickel-based hydroxide coprecipitation precursor, the precursor can be mixed with lithium raw materials and subjected to a heat treatment process at low temperatures to produce a single-particle positive electrode active material.

[0025] A method for producing a positive electrode active material precursor according to one embodiment includes the step of (a) mixing a nickel-based hydroxide and an inert lithium salt to produce a mixture. After mixing the unreactive inert lithium salt with the nickel-based hydroxide coprecipitation precursor, a heat treatment step is performed, followed by a washing step to obtain a positive electrode active material precursor in the form of well dispersed single particles. In some embodiments, the step of performing the first heat treatment step can be performed immediately after the step of mixing the nickel-based hydroxide and the inert lithium salt to prepare the mixture. In some embodiments, the water washing step can be performed immediately after the step of performing the first heat treatment step.

[0026] The nickel-based hydroxide is represented by chemical formula 1. [Chemical formula 1] Ni x1 M1 y1 M2 z1 (OH)2

[0027] In Chemical Formula 1, 0.3 ≦ x1 ≦ 1, 0 ≦ y1 ≦ 0.7, 0 ≦ z1 ≦ 0.7, and 0.9 ≦ x1 + y1 + z1 ≦ 1.1, and M1 and M2 are each independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zn, Y, and Zr. At this time, M1 and M2 can be different elements from each other.

[0028] In Chemical Formula 1, 0.6 ≦ x1 ≦ 1, 0 ≦ y1 ≦ 0.4, and 0 ≦ z1 ≦ 0.4, or 0.8 ≦ x1 ≦ 1, 0 ≦ y1 ≦ 0.2, and 0 ≦ z1 ≦ 0.2, or 0.9 ≦ x1 < 1, 0 < y1 ≦ 0.1, and 0 ≦ z1 ≦ 0.1 may be possible.

[0029] The inert lithium salt can include LiCl, Li2SO4, or a combination thereof, and specifically, LiCl can be used. When the nickel-based hydroxide and the inert lithium salt are used in the production of the cathode active material precursor, instead of the inert lithium salt reacting with the nickel-based hydroxide, the nickel-based hydroxide particles are grown to induce a single-particle form with excellent dispersibility, and a single-particle form cathode active material precursor with excellent dispersibility can be produced. Thereby, a single-particle form cathode active material having high crystallinity even at low temperatures can be produced.

[0030] The molar ratio of the nickel-based hydroxide to the inert lithium salt may be 0.1:1 to 10:1, for example, 0.2:1 to 8:1, 0.3:1 to 6:1, 0.4:1 to 4:1, or 0.5:1 to 2:1. When the molar ratio of the nickel-based hydroxide to the inert lithium salt is within the above range, a single-particle form cathode active material precursor with excellent dispersibility can be produced to produce a single-particle form cathode active material having high crystallinity even at low temperatures.

[0031] The method for manufacturing a positive electrode active material precursor according to an embodiment includes (b) a step of subjecting the mixture to a first heat treatment to obtain a nickel-based oxide in a single particle form. After mixing a non-reactive inert lithium salt with a co-precipitation precursor which is a nickel-based hydroxide, a positive electrode active material precursor which is a well-dispersed nickel-based oxide in a single particle form can be obtained through a heat treatment process. Since the above manufacturing method does not require an excessive lithium raw material or an additional pulverization process, the process is simple and cost reduction is possible. In some embodiments, the first heat treatment is performed at a first temperature of 500°C to 1,000°C, for example, 550°C to 950°C, 600°C to 900°C, 600°C to 800°C, or 600°C to 700°C, and then may be performed at a second temperature higher than the first temperature of 600°C to 1,000°C, for example, 650°C to 950°C, 700°C to 900°C, 750°C to 900°C, or 8,00°C to 900°C. The first heat treatment at the first temperature can be carried out for 1 hour to 12 hours, for example, 6 hours to 12 hours, or 8 hours to 12 hours, and the first heat treatment at the second temperature can be carried out for 1 hour to 12 hours, for example, 1 hour to 1,0 hours, 1 hour to 5 hours, 1 hour to 3 hours, or 1 hour to 2 hours. The first heat treatment can be carried out in an oxygen atmosphere.

[0032] The first heat treatment can be carried out at a temperature of 500°C to 1,000°C, for example, at a temperature of 550°C to 9,50°C, or at a temperature of 600°C to 900°C. Also, the first heat treatment can be carried out for 1 hour to 24 hours, for example, 6 hours to 18 hours, or 8 hours to 12 hours.

[0033] The nickel-based oxide is represented by Chemical Formula 2. [Chemical Formula 2] Ni x2 M3 y2 M4 z2 O 2-b2 X b2

[0034] In Chemical Formula 2, 0.3 ≦ x2 ≦ 1, 0 ≦ y2 ≦ 0.7, 0 ≦ z2 ≦ 0.7, 0.9 ≦ x2 + y2 + z2 ≦ 1.1, and 0 ≦ b2 ≦ 0.1, where M3 and M4 are each independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zn, Y, and Zr, and X can be one or more elements selected from the group consisting of F, P, and S. At this time, M3 and M4 can be different elements from each other. In some embodiments, X may not be present (i.e., b2 = 0).

[0035] In Chemical Formula 2, 0.6 ≦ x2 ≦ 1, 0 ≦ y2 ≦ 0.4, and 0 ≦ z2 ≦ 0.4, or 0.8 ≦ x2 ≦ 1, 0 ≦ y2 ≦ 0.2, and 0 ≦ z2 ≦ 0.2, or 0.9 ≦ x2 < 1, 0 < y2 ≦ 0.1, and 0 ≦ z2 ≦ 0.1 may be possible.

[0036] The nickel-based oxide may substantially not contain lithium or may contain a small amount of lithium, and the lithium content relative to 100 mol% of the entire nickel-based oxide may be 0.01 mol% or less. For example, it may be 0 mol% to 0.01 mol%, or 0.001 mol% to 0.01 mol%.

[0037] After the step (b), a step of recovering the inert lithium salt mixed in the step (a) can be further included. In some embodiments, the step of recovering the inert lithium salt may be performed immediately after the water washing process. That is, the inert lithium salt only affects inducing the nickel-based hydroxide into the nickel-based oxide in a single-particle form and growing the single-particle form, and does not react with the nickel-based hydroxide. Therefore, there is an advantage that it can be reused through the step of recovering the inert lithium salt.

[0038] Positive electrode active material precursor The positive electrode active material precursor according to one embodiment includes a nickel-based oxide in a single-particle form and is characterized in that the span value according to the following Formula 1 is 0.85 to 1.48. [Formula 1] Span = (D90 - D10) / D50

[0039] In Equation 1, D10 represents the particle size at which the cumulative volume in the particle size distribution is 10% by volume, D50 represents the particle size at which the cumulative volume in the particle size distribution is 50% by volume, and D90 represents the particle size at which the cumulative volume in the particle size distribution is 90% by volume.

[0040] The average particle size (D50) of the positive electrode active material precursor may be 1.0 μm to 6.3 μm, for example, 1.3 μm to 4.8 μm, 1.6 μm to 3.5 μm, or 2.0 μm to 3.0 μm. Furthermore, the D90 of the positive electrode active material precursor may be 4.0 μm to 10 μm, for example, 4.4 μm to 8.5 μm, 4.7 μm to 7.8 μm, or 5.0 μm to 7.5 μm. Therefore, the span value of the positive electrode active material precursor is characterized by being 0.85 to 1.48, for example, 0.85 to 1.38, or 0.9 to 1.23. In other words, by containing nickel-based oxide in single-particle form with uniform size, the positive electrode active material precursor can prevent cracking due to volume changes of particles that occur during continuous charging / discharging, thereby maintaining performance.

[0041] The nickel oxide contained in the positive electrode active material precursor is represented by the chemical formula 2.

[0042] The nickel-based oxide may contain substantially no lithium or only a small amount of lithium, and the lithium content relative to 100 mol% of the total nickel-based oxide may be 0.01 mol% or less, for example, 0 mol% to 0.01 mol%, or 0.001 mol% to 0.01 mol%.

[0043] positive electrode active material The positive electrode active material according to one embodiment is characterized by comprising a lithium nickel-based composite oxide and being in single-particle form. Here, the single particle may be spherical, ellipsoidal, plate-like, irregularly shaped, or a combination thereof.

[0044] The average particle size (D 50 ) of the single particles may be 0.5 μm to 5 μm, for example, 0.7 μm to 5 μm, 0.8 μm to 5 μm, 1 μm to 5 μm, or 1.5 μm to 4 μm. Here, the average particle size (D 50 ) can be obtained by randomly measuring more than 20 particle sizes (diameter or length of the long axis) from a scanning electron microscope image of the positive electrode active material to obtain a particle size distribution, and taking the diameter of the particle with a cumulative volume of 50% by volume in the particle size distribution as the average particle size. When the particle size of the single particles satisfies the above range, the energy density of the positive electrode can be maximized, the movement of lithium ions can be assisted smoothly, and while achieving high capacity, the life characteristics and efficiency characteristics of the battery can be improved at the same time.

[0045] The lithium nickel-based composite oxide of the positive electrode active material is represented by Chemical Formula 3. [Chemical Formula 3] Li a3 Ni x3 M5 y3 M6 z3 O 2-b3 X b3

[0046] In Chemical Formula 3, 0.9 ≤ a3 ≤ 1.8, 0.3 ≤ x3 ≤ 1, 0 ≤ y3 ≤ 0.7, 0 ≤ z3 ≤ 0.7, 0.9 ≤ x3 + y3 + z3 ≤ 1.1, and 0 ≤ b3 ≤ 0.1, M5 and M6 are each independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zn, Y, and Zr, and X is one or more elements selected from the group consisting of F, P, and S. At this time, M5 and M6 can be different elements from each other. In some embodiments, X may not be present (i.e., b3 = 0).

[0047] In Chemical Formula 3, 0.6 ≤ x3 ≤ 1, 0 ≤ y3 ≤ 0.4, and 0 ≤ z3 ≤ 0.4, or 0.8 ≤ x3 ≤ 1, 0 ≤ y3 ≤ 0.2, and 0 ≤ z3 ≤ 0.2, or 0.9 ≤ x3 < 1, 0 < y3 ≤ 0.1, and 0 ≤ z3 ≤ 0.1 may be satisfied.

[0048] As an example, the positive electrode active material may be a high-nickel positive electrode active material in which the nickel content relative to 100 mol% of the metal excluding lithium is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less. High-nickel positive electrode active materials can achieve high capacity and can be applied to high-capacity, high-density lithium secondary batteries.

[0049] Method for manufacturing positive electrode active material A method for producing a positive electrode active material according to one embodiment includes the step of mixing the positive electrode active material precursor produced by the method for producing the positive electrode active material precursor with a lithium raw material and performing a second heat treatment.

[0050] Another embodiment of the method for producing a positive electrode active material includes the step of mixing the positive electrode active material precursor with a lithium raw material and performing a second heat treatment.

[0051] The positive electrode active material precursor 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, 1:1.03 to 1.1, or 1:1 to 1:1.2.

[0052] The lithium raw material here may be a different compound from the inert lithium salt described above, and may include, for example, lithium hydroxide, lithium carbonate, their hydrates, their anhydrous forms, or combinations thereof.

[0053] The second heat treatment can be carried out in an oxygen atmosphere, for example, in a temperature range of 600°C to 850°C, or 650°C to 800°C, or 680°C to 750°C, for 2 to 20 hours, or 4 to 12 hours.

[0054] Lithium-ion battery In one embodiment, a lithium secondary battery is provided, comprising a positive electrode, a negative electrode, and an electrolyte. Here, the electrolyte may be a liquid electrolyte or a solid electrolyte.

[0055] For example, in one embodiment, a lithium secondary battery can be provided that includes a positive electrode, a negative electrode, a separator located between the positive and negative electrodes, and an electrolyte. In another example, an all-solid-state secondary battery can be provided that includes a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive and negative electrodes.

[0056] The following describes a lithium secondary battery using an electrolyte solution as an example.

[0057] Lithium secondary batteries can be 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 secondary battery according to one embodiment, where Figure 1 may be cylindrical, Figure 2 rectangular, and Figures 3 and 4 pouch-type batteries. Referring to Figures 1 to 4, the lithium secondary battery 100 may include an electrode assembly 40 with a separator 30 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 secondary battery 100 may include a sealing member 60 that seals the case 50, as shown in Figure 1. Also, in Figure 2, the lithium secondary battery 100 may include a positive electrode lead tab 11 and a positive electrode terminal 12, a negative electrode lead tab 21 and a negative electrode terminal 22. As shown in Figures 3 and 4, the lithium secondary battery 100 may include electrode tabs 70, namely a positive electrode tab 71 and a negative electrode tab 72, which serve as electrical pathways for guiding the current formed in the electrode assembly 40 to the outside.

[0058] positive electrode The positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material and may further include a binder and / or conductive material. A detailed explanation of the positive electrode active material has been given above, so it will not be explained further.

[0059] 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 that can be used 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, acrylic styrene-butadiene rubber, epoxy resin, and nylon.

[0060] 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 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 conductive materials containing mixtures thereof.

[0061] Aluminum foil can be used as the positive electrode current collector, but is not limited to it.

[0062] negative electrode The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0063] negative electrode active material The negative electrode active material includes a substance capable of reversibly inserting / de-inserting lithium ions, lithium metal, an alloy of lithium metal, a lithium-doped and de-doped substance, or a transition metal oxide.

[0064] As the substance capable of reversibly inserting / desorbing the lithium ions, a carbon-based negative electrode active material can be used, for example, including crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flaky, spherical or fibrous natural graphite, or artificial graphite. Examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0065] As the alloy of the lithium metal, 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.

[0066] As the substance capable of doping and undoping lithium, an Si-based negative electrode active material or an Sn-based negative electrode active material can be used. The Si-based negative electrode active material can be silicon, a silicon-carbon composite, SiOx (0 < x < 2), an Si-Q alloy (where Q is an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and 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. The Sn-based negative electrode active material can be Sn, SnO2, an Sn alloy, or a combination thereof.

[0067] The silicon-carbon composite can be a composite of silicon and amorphous carbon. The average particle size (D) of the silicon-carbon composite particles 50The particle size can 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 secondary particles (core) 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, for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in the amorphous carbon matrix.

[0068] 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. The amorphous carbon may be soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0069] When the silicon-carbon composite contains silicon and amorphous carbon, the silicon content may be 10% to 50% by weight per 100% by weight of the silicon-carbon composite, and the amorphous carbon content may be 50% to 90% by weight. Furthermore, when the composite contains silicon, amorphous carbon, and crystalline carbon, the silicon content may be 10% to 50% by weight per 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.

[0070] Furthermore, 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 The size of the silicon particles may be 10 nm to 1 μm, or 10 nm to 200 nm. The silicon particles may exist as silicon alone, as a silicon alloy, or as an oxidized form. The oxidized form of silicon is SiO xIt can be represented by (0 < x < 2). At this time, the ratio of the atomic content of Si:O indicating the degree of oxidation can 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.

[0071] The Si-based negative electrode active material or 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 Sn-based negative electrode active material and the carbon-based negative electrode active material are used in combination, the mixing ratio can be 1:99 to 90:10 by weight ratio. <0​​​​​​​​​​​​​​​​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.

[0076] 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.

[0077] 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, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0078] 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.

[0079] electrolyte The electrolyte for lithium secondary batteries may, for example, be an electrolyte solution, which may contain a non-aqueous organic solvent and a lithium salt.

[0080] Non-aqueous organic solvents act as a medium through which ions involved in the electrochemical reactions of a battery can move. Non-aqueous organic solvents can be carbonate, ester, ether, ketone, or alcoholic solvents, aprotic solvents, or combinations thereof.

[0081] 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.

[0082] Non-aqueous organic solvents can be used alone or in combination of two or more. When used in combination of two or more, the mixing ratio can be appropriately adjusted according to the desired battery performance, which is generally understood by those working in this field.

[0083] When using carbonate-based solvents, cyclic carbonates and linear carbonates can be mixed, and these can be mixed in a volume ratio of 1:1 to 1:9.

[0084] Non-aqueous organic solvents may further include aromatic hydrocarbon organic solvents. For example, carbonate solvents and aromatic hydrocarbon organic solvents can be mixed and used in a volume ratio of 1:1 to 30:1.

[0085] The electrolyte may further contain vinyl ethyl carbonate, vinylene carbonate, or ethylene carbonate compounds to improve battery life.

[0086] 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.

[0087] Lithium salts dissolve in organic solvents and act as a source of lithium ions within 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(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate) borate (LiBOB).

[0088] The lithium salt concentration is preferably within the 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.

[0089] 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.

[0090] The separator may include a porous substrate and a coating layer containing organic, inorganic, or a combination thereof located on one or both sides of the porous substrate.

[0091] The porous substrate may be a polymer film formed from 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, Teflon®, and polytetrafluoroethylene, or from a copolymer or mixture of two or more of these polymers.

[0092] 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.

[0093] 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.

[0094] 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) of the inorganic particles is 50 The range is 1 nm to 2000 nm, and for example, it could be 100 nm to 1000 nm or 100 nm to 700 nm.

[0095] The organic and inorganic materials may exist mixed together 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 stacked on top of each other.

[0096] The thickness of the coating layer is 0.5 μm to 20 μm, and can be, for example, 1 μm to 10 μm, or 1 μm to 5 μm.

[0097] The following describes examples and comparative examples of the present invention. The following examples are merely illustrative of the present invention and are not limited to the following examples.

[0098] Examples Example 1 1. Manufacturing of the positive electrode active material precursor Ni 0.97 Co 0.02 Mn 0.01 (OH)2 and LiCl are mixed in a molar ratio of 1:2 and subjected to a first heat treatment at 600°C for 10 hours and 900°C for 1 hour in an oxygen atmosphere, resulting in a composition of Ni 0.97 Co 0.02 Mn 0.01 A nickel-based oxide in single-particle form, consisting of O2 with an average particle size (D50) of approximately 2.6 μm, was prepared. The nickel-based oxide was then washed by adding 10 ml of water per 0.4 g of nickel-based oxide and stirring for 30 minutes.

[0099] 2. Manufacturing of positive electrode active material The manufactured nickel oxide and LiOH were mixed in a 1:1 molar ratio and subjected to a second heat treatment at 700°C for 10 hours in an oxygen atmosphere, resulting in a composition of LiNi 0.97 Co 0.02 Mn 0.01 A cathode active material containing a lithium nickel-based composite oxide in single-particle form, which is O2 and has an average particle size (D50) of approximately 3.2 μm, was manufactured.

[0100] 3. 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 the cathode.

[0101] A half-cell was manufactured using the aforementioned positive electrode, lithium metal counter electrode, and electrolyte in a conventional manner. A polyethylene separator was used, and the electrolyte was a solution of ethylene carbonate and dimethyl carbonate mixed in a volume ratio of 3:7 with 1M LiPF6 dissolved in it.

[0102] Example 2 The cathode active material precursor, cathode active material, and lithium secondary battery were manufactured in substantially the same manner as in Example 1, except that the cathode active material precursor was subjected to a first heat treatment at 600°C for 10 hours and 800°C for 5 hours.

[0103] Example 3 The cathode active material precursor, cathode active material, and lithium secondary battery were manufactured in substantially the same manner as in Example 1, except that the cathode active material precursor was subjected to a first heat treatment at 600°C for 10 hours and 750°C for 5 hours.

[0104] Example 4 The cathode active material precursor, cathode active material, and lithium secondary battery were manufactured in substantially the same manner as in Example 1, except that Li2SO4 was used instead of LiCl in the production of the cathode active material precursor, and a first heat treatment was performed at 870°C for 10 hours and at 900°C for 1 hour.

[0105] Example 5 The cathode active material precursor, cathode active material, and lithium secondary battery were manufactured in substantially the same manner as in Example 4, except that the cathode active material precursor was subjected to a first heat treatment at 870°C for 10 hours and at 900°C for 3 hours.

[0106] Example 6 The cathode active material precursor, cathode active material, and lithium secondary battery were manufactured in substantially the same manner as in Example 4, except that the cathode active material precursor was subjected to a first heat treatment at 870°C for 10 hours and 900°C for 10 hours.

[0107] Comparative Example 1 The positive electrode active material precursor, positive electrode active material, and lithium secondary battery were manufactured in substantially the same manner as in Example 1, except that LiCl was not used in the production of the positive electrode active material precursor.

[0108] Comparative Example 2 Ni 0.97 Co 0.02 Mn 0.01 (OH)2 and LiOH are mixed in a 1:1 molar ratio and heat-treated at 800°C for 10 hours in an oxygen atmosphere, resulting in a composition of LiNi 0.97 Co 0.02 Mn 0.01 A positive electrode active material containing a lithium nickel-based composite oxide, which is O2 and has an average particle size (D50) of approximately 2.38 μm, was manufactured.

[0109] Subsequently, the lithium secondary battery was manufactured in substantially the same manner as in Example 1.

[0110] Evaluation Example 1: X-ray Diffraction (XRD) Analysis X-ray diffraction (XRD) analysis was performed on the cathode active material precursors of the examples and comparative examples, and the results are shown in Figures 5 and 6. The XRD analysis was performed using a Bruker Powder XRD (D2 PHASER) instrument under the following conditions.

[0111] -X-ray wavelength: 1.5406Å (CuK α 1) - Slit conditions: Divergence Slit 0.6mm, Scattering Slit 3mm, Receiving Slit 0.20mm - Scan conditions: Continuous Scan, 10°≦2θ≦80°, 0.02° / step, 1.2° / min, total measurement time 58 min Referring to Figures 5 and 6, a comparison of the peaks observed in Comparative Example 1, which does not use an inert lithium salt in the production of the positive electrode active material precursor, with the peaks observed in Example 1 using LiCl or Example 4 using Li2SO4, confirms that lithium is not included in the crystal structure even in Example 1 or Example 4, which use an inert lithium salt in the production of the positive electrode active material precursor. This confirms that the inert lithium salt does not react with nickel hydroxide and contributes to the growth of single particles while inducing nickel hydroxide particles into a single-particle shape.

[0112] Evaluation Example 2: Surface Analysis 1. Cathode active material precursor The cathode active material precursors from the examples and comparative examples were compared using a scanning electron microscope (SEM).

[0113] Figure 7 is an SEM image of the surface of the positive electrode active material precursor produced by Example 1, Figure 8 is an SEM image of the surface of the positive electrode active material precursor produced by Example 2, and Figure 9 is an SEM image of the surface of the positive electrode active material precursor produced by Example 3.

[0114] Figure 10 is an SEM image of the surface of the positive electrode active material precursor produced by Example 4, Figure 11 is an SEM image of the surface of the positive electrode active material precursor produced by Example 5, and Figure 12 is an SEM image of the surface of the positive electrode active material precursor produced by Example 6.

[0115] In contrast, Figure 13 is an SEM image of the surface of the cathode active material precursor produced by Comparative Example 1.

[0116] Referring to Figures 7 to 13, in the example, a single-particle form is formed in the positive electrode active material precursor obtained by mixing nickel-based hydroxide and an inert lithium salt and heat-treating them. However, in Comparative Example 1, it can be confirmed that in the positive electrode active material precursor obtained by heat-treating only nickel-based hydroxide without mixing in an inert lithium salt, the form is not a single-particle form, but rather a secondary particle form in which primary particles with a particle size of several hundred nanometers are aggregated.

[0117] Furthermore, Figures 7-9 and 10-12 confirm that the size of the single-particle positive electrode active material precursor can be uniformly controlled by the first heat treatment temperature and conditions. This confirms that the inert lithium salt does not react with nickel-based hydroxide and contributes to the growth of single particles while inducing nickel-based hydroxide particles into a single-particle shape.

[0118] 2.Cathode active material The positive electrode active materials from the examples and comparative examples were compared using a scanning electron microscope (SEM).

[0119] Figure 14 is an SEM image of the surface of the positive electrode active material produced by Example 1, Figure 15 is an SEM image of the surface of the positive electrode active material produced by Comparative Example 1, and Figure 16 is an SEM image of the surface of the positive electrode active material produced by Comparative Example 2.

[0120] Referring to Figures 14 to 16, it can be confirmed that in the case of the positive electrode active material of Comparative Example 1, which was produced by first heat-treating only nickel-based hydroxide without mixing with an inert lithium salt and then performing a second heat-treatment on the positive electrode active material precursor, single particles were not formed, and instead, aggregation occurred, producing secondary particles. Similarly, in the case of the positive electrode active material of Comparative Example 2, which was produced by heat-treating nickel-based hydroxide and lithium raw material without going through a nickel-based oxide precursor, it can be confirmed that single particles were not successfully produced. In contrast, in the case of the positive electrode active material precursor produced by mixing nickel-based hydroxide and an inert lithium salt and then calcining it, as in the example, it can be confirmed that single particle morphology was formed.

[0121] Evaluation Example 3: Initial Charge / Discharge Capacity and Efficiency Evaluation The lithium secondary batteries manufactured in the examples and comparative examples were charged at 25°C with a constant current of 0.2C to an upper voltage limit of 4.3V, then with a constant voltage down to 0.05C, and finally discharged at 0.2C down 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 using efficiency.

[0122] Evaluation Example 4: Lifetime Characteristics Following the initial charge and discharge in Evaluation Example 3, the cycle of charging to 1.0C and discharging to 1.0C at 45°C in a voltage range of 3.0V to 4.3V was repeated 20 or more times, and the ratio of the discharge capacity after 20 cycles to the initial discharge capacity was calculated and is shown in Table 1 below.

[0123] [Table 1]

[0124] Referring to Table 1, it can be confirmed that the example containing a single-particle positive electrode active material exhibits superior efficiency and lifetime characteristics compared to the comparative example containing a secondary-particle positive electrode active material. Generally, single particles have the disadvantage of having poorer ion conductivity and lower efficiency compared to secondary particles, but it can be confirmed that the example improved efficiency by achieving a very uniform particle size.

[0125] Evaluation Example 5: Recovery Analysis of Inert Lithium Salts Figure 17 shows the results of Raman spectroscopy (RAMAN) analysis to determine whether the inert lithium salt can be recovered after the production of the cathode active material precursor according to the examples. The Raman analysis was performed using DXR2xi (Thermo Scientific) under the following conditions.

[0126] -Wavelength laser: 532nm - Minimum Raman shift: ~50cm -1 -Spatial resolution: 500nm - Measurement range: 50~3500cm -1 Referring to Figure 17, it can be confirmed that after producing the positive electrode active material precursor according to the example, the peak of the recovered inert lithium salt matches the reference peak of each inert lithium salt, thereby confirming that the inert lithium salt used in the production of the positive electrode active material precursor can be recovered.

[0127] 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 that utilize the basic concepts defined in the claims also fall within the scope of the present invention. [Explanation of Symbols]

[0128] 100 Lithium-ion rechargeable batteries 10 positive electrode 11 Positive lead tab 12 Positive terminal 20 negative electrode 21 Negative lead tab 22 Negative terminal 30 Separators 40 Electrode assembly 50 cases 60 Sealing member 70 electrode tabs 71 Positive Tab 72 Negative Electrode Tabs

Claims

1. (a) A step of mixing nickel hydroxide and an inert lithium salt to produce a mixture, (b) The step of first heat-treating the mixture to obtain nickel-based oxide in single-particle form, A method for producing a cathode active material precursor in single-particle form containing [the specified substance].

2. The nickel-based hydroxide is represented by chemical formula 1, and the method for producing a positive electrode active material precursor according to claim 1: [Chemical formula 1] 90 x1 11 y1 2. The z1 (10) 2 In chemical formula 1, 0.3 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.7, and 0.9 ≤ x1 + y1 + z1 ≤ 1.1, and M1 and M2 are each independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zn, Y, and Zr, and M1 and M2 are different elements from each other.

3. The aforementioned inert lithium salt is LiCl, Li 2 SO 4 A method for producing a positive electrode active material precursor according to claim 1, comprising, or a combination thereof.

4. A method for producing a positive electrode active material precursor according to claim 1, wherein the molar ratio of the nickel-based hydroxide to the inert lithium salt is 0.1:1 to 10:

1.

5. The method for producing a positive electrode active material precursor according to claim 1, wherein the first heat treatment is performed at a temperature of 500°C to 1,000°C for 1 to 24 hours.

6. The nickel oxide is represented by chemical formula 2, and the method for producing a positive electrode active material precursor according to claim 1: [Chemical formula 2] ii x2 73 y2 74 z2 9 2-b2 8 b2 In chemical formula 2, 0.3 ≤ x² ≤ 1, 0 ≤ y² ≤ 0.7, 0 ≤ z² ≤ 0.7, 0.9 ≤ x² + y² + z² ≤ 1.1, and 0 ≤ b² ≤ 0.

1. M3 and M4 are each independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zn, Y, and Zr. M3 and M4 are different elements from each other, and X is one or more elements selected from the group consisting of F, P, and S.

7. The method for producing a positive electrode active material precursor according to claim 1, wherein the nickel-based oxide contains lithium in an amount of 0.01 mol% or less relative to 100 mol% of the total nickel-based oxide.

8. A method for producing a cathode active material precursor according to claim 1, further comprising the step of recovering an inert lithium salt after step (b) above.

9. Containing nickel-based oxide in single-particle form, A positive electrode active material precursor having a span value of 0.85 to 1.48 according to the following formula 1: [Formula 1] Span = (D90 - D10) / D50 In Equation 1, D10 represents the particle size at which the cumulative volume in the particle size distribution is 10% by volume, D50 represents the particle size at which the cumulative volume in the particle size distribution is 50% by volume, and D90 represents the particle size at which the cumulative volume in the particle size distribution is 90% by volume.

10. The positive electrode active material precursor according to claim 9, wherein the average particle size (D50) of the positive electrode active material precursor is 1.0 μm to 6.3 μm.

11. The positive electrode active material precursor according to claim 9, wherein the nickel-based oxide contains lithium in an amount of 0.01 mol% or less based on 100 mol% of the total nickel-based oxide.

12. A method for producing a positive electrode active material, comprising the step of mixing a positive electrode active material precursor produced by the manufacturing method described in any one of claims 1 to 8 with a lithium raw material and performing a second heat treatment.

13. A method for producing a positive electrode active material, comprising the step of mixing a positive electrode active material precursor according to any one of claims 9 to 11 with a lithium raw material and performing a second heat treatment.

14. The method for producing a positive electrode active material according to claim 12, wherein the second heat treatment is performed in a temperature range of 600°C to 850°C.

15. The method for producing a positive electrode active material according to claim 13, wherein the second heat treatment is performed in a temperature range of 600°C to 850°C.

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