Positive electrode active material precursor, method for producing a positive electrode active material using the same, and positive electrode active material

Abstract

The present invention relates to a cathode active material precursor that can realize a cathode active material in a single particle form even when heat-treated at a low temperature, and specifically relates to a cathode active material precursor including one or more selected from a first cathode active material precursor having a composition represented by Chemical Formula 1 described in the present specification and containing a composite transition metal in a single particle form, a second cathode active material precursor having a composition represented by Chemical Formula 2 described in the present specification, and a third cathode active material precursor having a composition represented by Chemical Formula 3 described in the present specification, a method for producing a cathode active material using the same, and a cathode active material produced thereby.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0062289 filed on May 20, 2022, and all the contents disclosed in the document of the Korean Patent Application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a positive electrode active material precursor, a method for manufacturing a positive electrode active material using the same, and a positive electrode active material manufactured thereby.

Background Art

[0003] In recent years, with the development of technologies and the increasing demand for mobile devices and electric vehicles, the demand for secondary batteries as an energy source has been rapidly increasing. Among such secondary batteries, lithium secondary batteries having high energy density, high voltage, long cycle life, and low self-discharge rate have been commercialized and widely used.

[0004] As positive electrode active materials for lithium secondary batteries, lithium transition metal oxides such as lithium cobalt oxides such as LiCoO2, lithium nickel oxides such as LiNiO2, lithium manganese oxides such as LiMnO2 or LiMn2O4, and lithium iron phosphate oxides such as LiFePO4 have been developed. In recent years, lithium composite transition metal oxides containing two or more transition metals such as a Co b Mn c O2, a Co b Al c O2, a Co b Mn c Al d O2 have been developed and widely used.

[0005] Lithium transition metal oxides developed to date are typically produced by a coprecipitation reaction in which ammonia water, a chelating agent, and sodium hydroxide aqueous solution, a basic aqueous solution, are added to a solvent containing transition metal raw materials, such as nickel sulfate, cobalt sulfate, and manganese sulfate. The lithium transition metal hydroxide is then mixed with lithium-containing raw materials and selectively doping element-containing raw materials, and subsequently subjected to high-temperature heat treatment.

[0006] As described above, when manufacturing lithium transition metal hydroxides, a lithium transition metal hydroxide having the form of spherical secondary particles formed by the aggregation of primary particles ranging from several nanometers to tens of nanometers in size is formed as a positive electrode active material precursor. To manufacture a positive electrode active material in the form of single particles using this precursor, high-temperature heat treatment of 830°C or higher is required.

[0007] However, when high-temperature heat treatment above 830°C is performed to produce single-particle positive electrode active material, the R-3m layered structure is not sufficiently maintained, and lithium passes outside the crystalline structure, causing a phase change to an Fm-3m rock-salt structure such as NiO. This leads to a decrease in the crystallinity of the positive electrode active material, resulting in problems such as a decrease in the capacity characteristics and lifespan characteristics of batteries containing the positive electrode active material, and a large increase in resistance. On the other hand, when heat treatment is performed at temperatures below 830°C, the material exists in the form of over-calcined secondary particles, resulting in problems where the improvement in lifespan and gas generation does not meet the level expected for single particles.

[0008] Therefore, research is being conducted to develop cathode active material precursors that do not require high-temperature heat treatment above 830°C to enhance the crystallinity of the cathode active material during the production of single-particle cathode active materials. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The object of the present invention is to provide a cathode active material precursor that can realize a cathode active material in single-particle form even when fired at low temperatures.

[0010] Furthermore, by using the positive electrode active material precursor during the production of the positive electrode active material, a method for producing a positive electrode active material that can be obtained in single-particle form even when calcined at low temperatures is provided. [Means for solving the problem]

[0011] To solve the above problems, the present invention provides a positive electrode active material precursor, a method for producing a positive electrode active material using the same, and a positive electrode active material produced thereby.

[0012] (1) The present invention provides a cathode active material precursor comprising: a first cathode active material precursor having a composition represented by the following chemical formula 1 and containing a single-particle composite transition metal; a second cathode active material precursor having a composition represented by the following chemical formula 2; and one or more third cathode active material precursors having a composition represented by the following chemical formula 3.

[0013] [Chemical formula 1] Ni a1 M 1 b1 Mn c1 M 2 d1

[0014] In the aforementioned chemical formula 1, M 1 is one or more selected from Co and Al, M 2 is one or more elements selected from Nb, Ti, Mg, Ta, Zr, Ca, Mo, V, Y, W, and Sc. 0.6 ≤ a1 < 1, 0 <b1≦0.4、0≦c1≦0.4、0≦d1≦0.2であり、 [Chemical formula 2] M 3 a2 M 4 b2 (OH) c2 In the aforementioned chemical formula 2, M 3 is one or more selected from Ni, Co, Mn, Al, and Zr. M 4 is one or more selected from Nb, Ti, Mg, Ta, Ca, Mo, V, Y, W, and Sc. 0 <a2≦1、0≦b2<1、2≦c2≦4であり、 [Chemical formula 3] M 5 a3 M 6 b3 O c3 In the aforementioned chemical formula 3, M 5 is one or more selected from Ni, Co, Mn, Al, and Zr. M 6 is one or more selected from Nb, Ti, Mg, Ta, Ca, Mo, V, Y, W, and Sc. 0 <a3≦3、0≦b3<3、1≦c3≦4である。

[0015] (2) The present invention provides that the first positive electrode active material precursor has an average particle size (D 50 The present invention provides a positive electrode active material precursor as described in (1) above, wherein the diameter is 0.1 μm to 15 μm.

[0016] (3) The present invention provides the positive electrode active material precursor described in (1) or (2) above, wherein the first positive electrode active material precursor has a face-centered cubic crystal structure.

[0017] (4) The present invention provides a positive electrode active material precursor according to any one of (1) to (3) above, wherein the second positive electrode active material precursor is in the form of secondary particles, single particles, or an amorphous form.

[0018] (5) The present invention provides that the second positive electrode active material precursor has an average particle size (D 50 The present invention provides a positive electrode active material precursor according to any one of (1) to (4) above, wherein the diameter is 0.01 μm to 10 μm.

[0019] (6) The present invention provides a positive electrode active material precursor according to any one of (1) to (5) above, wherein the third positive electrode active material precursor is in the form of secondary particles, single particles, or an amorphous form.

[0020] (7) The present invention provides that the third positive electrode active material precursor has an average particle size (D 50 The present invention provides a positive electrode active material precursor according to any one of (1) to (6) above, wherein the diameter is 0.01 μm to 10 μm.

[0021] (8) The present invention provides a positive electrode active material precursor according to any one of (1) to (7) above, wherein the positive electrode active material precursor comprises one or more selected from the second positive electrode active material precursor and the third positive electrode active material precursor in an amount of 0.5 to 5 parts by weight per 100 parts by weight of the first positive electrode active material precursor.

[0022] (9) The present invention provides a method for producing a positive electrode active material, comprising the step of mixing a positive electrode active material precursor described in any one of (1) to (8) above with a lithium-containing raw material, and then firing it at a temperature of 700°C or higher and less than 830°C to obtain a lithium transition metal oxide in single-particle form.

[0023] (10) The present invention is manufactured by the method described in (9) above, and the average particle size (D 50 The present invention provides a positive electrode active material in single-particle form with a diameter of 3 μm to 12 μm.

[0024] (11) The present invention relates to the average particle size (D 50 The present invention provides a positive electrode active material in the form of a single particle as described in (10), wherein the diameter is 4 μm to 8 μm. [Effects of the Invention]

[0025] The positive electrode active material precursor according to the present invention is used by mixing a first positive electrode active material precursor containing a single-particle composite transition metal with a second positive electrode active material precursor and / or a third positive electrode active material precursor. Therefore, even if the positive electrode active material precursor is calcined at a relatively lower temperature than the temperature conventionally required to form single particles during the production of the positive electrode active material, a positive electrode active material in single-particle form can be obtained.

[0026] The positive electrode active material produced by the method for producing positive electrode active material according to the present invention can achieve excellent capacity characteristics, life characteristics, resistance characteristics, and a significant reduction in gas generation when applied to a secondary battery. [Brief explanation of the drawing]

[0027] [Figure 1] This is an SEM image of the first cathode active material precursor used in Example 1. [Figure 2] This is an SEM image of nickel-cobalt-manganese hydroxide used in Comparative Example 1. [Figure 3] This is an SEM image of the nickel-cobalt-manganese oxide used in Comparative Example 2. [Figure 4] This is a volume cumulative particle size graph of the positive electrode active materials produced in Example 1, Comparative Examples 1 and 2. [Figure 5] (A) SEM images of the positive electrode active materials produced in Example 1, (B) Comparative Example 1, and (C) Comparative Example 2. [Figure 6] These are the XRD data of the positive electrode active materials produced in Example 1 and Comparative Example 1. [Figure 7] These are the XRD data for the first cathode active material precursor and the third cathode active material precursor used in Example 1. [Figure 8] This is the EDS data for the first cathode active material precursor used in Example 1. [Modes for carrying out the invention]

[0028] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0029] In this specification, terms such as “includes,” “equip,” or “have” are intended to specify the presence of implemented features, figures, steps, components, or combinations thereof, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, figures, steps, components, or combinations thereof.

[0030] In this specification, the average particle size (D 50 ) refers to the particle size at the 50% reference level of the volume cumulative particle size distribution of the positive electrode active material precursor, positive electrode active material, or lithium transition metal oxide powder. The average particle size (D 50 The particle size can be measured by the laser diffraction method. For example, after dispersing the positive electrode active material powder in a dispersion medium, the particle size can be measured by introducing it into a commercially available laser diffraction particle size analyzer (e.g., Microtrac MT 3000) and irradiating it with ultrasound at approximately 28 kHz with an output of 60 W, obtaining a volume cumulative particle size distribution graph, and then determining the particle size corresponding to 50% of the volume cumulative amount.

[0031] In this specification, the term "on top of" means not only when one configuration is formed directly on top of another, but also when a third configuration is interposed between those configurations.

[0032] In this specification, single-particle morphology is a concept contrasted with spherical secondary particle morphology formed by the aggregation of tens to hundreds of primary particles manufactured by conventional methods, and may include morphologies in which particles are separated and / or dispersed from one another so as to form independent and / or distinct phases for each particle, or morphologies in which 2 to 10 or 2 to 5 particles are attached to each other.

[0033] The present invention will be described in detail below.

[0034] Cathode active material precursor The positive electrode active material precursor according to the present invention comprises a first positive electrode active material precursor having a composition represented by the following chemical formula 1 and containing a single-particle composite transition metal, a second positive electrode active material precursor having a composition represented by the following chemical formula 2, and one or more third positive electrode active material precursors having a composition represented by the following chemical formula 3.

[0035] [Chemical formula 1] Ni a1 M 1 b1 Mn c1 M 2 d1

[0036] In the aforementioned chemical formula 1, M 1 is one or more selected from Co and Al, M 2 is one or more elements selected from Nb, Ti, Mg, Ta, Zr, Ca, Mo, V, Y, W, and Sc. 0.6 ≤ a1 < 1, 0 <b1≦0.4、0≦c1≦0.4、0≦d1≦0.2であり、 [Chemical formula 2] M 3 a2 M 4 b2 (OH) c2 In the aforementioned chemical formula 2, M 3 is one or more selected from Ni, Co, Mn, Al, and Zr. M 4 is one or more selected from Nb, Ti, Mg, Ta, Ca, Mo, V, Y, W, and Sc. 0 <a2≦1、0≦b2<1、2≦c2≦4であり、 [Chemical formula 3] M 5 a3 M 6 b3 O c3 In the aforementioned chemical formula 3, M 5 is one or more selected from Ni, Co, Mn, Al, and Zr. M6 is one or more selected from Nb, Ti, Mg, Ta, Ca, Mo, V, Y, W, and Sc. 0 <a3≦3、0≦b3<3、1≦c3≦4である。

[0037] The inventors of the present invention conducted extensive research to develop a positive electrode active material that can achieve excellent lifetime and resistance characteristics. As a result, they discovered that when a first positive electrode active material precursor, which is a single-particle composite transition metal, is mixed with a transition metal hydroxide and / or a transition metal oxide and used as the positive electrode active material precursor, a positive electrode active material with a high degree of single-particle formation that can achieve excellent lifetime and resistance characteristics can be manufactured even when fired at a relatively low temperature, thus completing the present invention.

[0038] Firstly, when using a positive electrode active material precursor having the form of secondary particles formed by the aggregation of conventional primary particles, high-temperature firing at 830°C or higher is required to produce a positive electrode active material in single-particle form. In contrast, when using a positive electrode active material precursor containing a first positive electrode active material precursor, which is a composite transition metal in single-particle form, and a transition metal hydroxide (second positive electrode active material precursor) and / or a transition metal oxide (third positive electrode active material precursor), as in the present invention, there is the advantage that a positive electrode active material in single-particle form can be produced even by firing at temperatures below 830°C. As a result, phase changes such as the NiO phase becoming a rock salt structure, which can occur when undergoing high-temperature firing at 830°C or higher, do not occur, and consequently, a positive electrode active material with superior performance can be produced.

[0039] Furthermore, because the positive electrode active material precursor according to the present invention contains an isotropic composite transition metal, the particles grow uniformly regardless of the growth direction and are easily formed into single particles.

[0040] According to the present invention, the first positive electrode active material precursor may be the composite transition metal itself in single-particle form having the composition represented by the chemical formula 1. Alternatively, the first positive electrode active material precursor may be a composite transition metal in single-particle form having the composition represented by the chemical formula 1 below, whose surface has been modified by reacting with oxygen and moisture in the atmosphere to form oxides, hydrates, etc.

[0041] In the aforementioned chemical formula 1, The a1 mentioned above represents the atomic fraction of nickel among the metal elements in the first positive electrode active material precursor, and may be 0.6 ≤ a1 < 1, 0.6 ≤ a1 ≤ 0.98, or 0.7 ≤ a1 ≤ 0.95. b1 is M among the metal elements in the first positive electrode active material precursor. 1 It means the atomic fraction of 0 <b1≦0.4、0.01≦b1≦0.4、または0.01≦b1≦0.3であってよい。 The aforementioned c1 represents the atomic fraction of manganese among the metal elements in the first positive electrode active material precursor, and may be 0 ≤ c1 ≤ 0.4, 0.01 ≤ c1 ≤ 0.4, or 0.01 ≤ c1 ≤ 0.3. The aforementioned d1 is M among the metal elements in the first positive electrode active material precursor. 2 This refers to the atomic fraction of an element, and may be 0≦d1≦0.2, 0≦d1≦0.1, or 0≦d1≦0.05.

[0042] The first positive electrode active material precursor may contain nickel and cobalt in order to improve the resistance characteristics of the battery. For example, it may have a composition represented by the following chemical formula 1-1.

[0043] [Chemical formula 1-1] Ni a1 Co x1 Al y1 Mn c1 M 2 d1

[0044] In the above chemical formula 1-1, M 2 is one or more elements selected from Nb, Ti, Mg, Ta, Zr, W, and Sc. 0.6 ≤ a1 < 1, 0 <x1≦0.4、0≦y1≦0.4、0≦c1≦0.4、0≦d1≦0.2である。

[0045] On the other hand, the first positive electrode active material precursor may be the composite transition metal itself in single-particle form having the composition represented by the following chemical formula 1. Furthermore, the surface of the composite transition metal in single-particle form having the composition represented by the following chemical formula 1 may be surface-modified by a reaction with oxygen and moisture in the atmosphere to form oxides, hydrates, etc.

[0046] According to the present invention, the first positive electrode active material precursor has an average particle size (D 50 The particle size may be 0.1 μm to 15 μm. Specifically, the first positive electrode active material precursor has an average particle size (D 50 The particle size may be 0.1 μm, 2 μm, 3 μm, 5 μm or more, 10 μm, 12 μm, or 15 μm or less. When the average particle size of the first positive electrode active material precursor is within the above range, the number of lithium paths in contact with the electrolyte increases, and the number of reversibly usable lithium ions increases, thus enabling high capacity and power characteristics.

[0047] According to the present invention, the first positive electrode active material precursor may have a face-centered cubic crystal structure. When the crystal structure of the first positive electrode active material precursor is face-centered cubic, due to the close-packed characteristics of the face-centered cubic structure, a large amount of positive electrode active material can be produced from a small volume and weight of precursor, thereby improving process efficiency.

[0048] The second positive electrode active material precursor may be Ni(OH)2, Co(OH)2, Zr(OH)4, Al(OH)3, or a combination thereof, in order to improve the low reactivity of the first positive electrode active material precursor.

[0049] According to the present invention, the second positive electrode active material precursor may be in the form of secondary particles, single particles, or amorphous.

[0050] According to the present invention, the second positive electrode active material precursor has an average particle size (D 50 The particle size may be 0.01 μm to 10 μm. Specifically, the second positive electrode active material precursor has an average particle size (D 50The particle size may be 0.01 μm, 0.1 μm, 1 μm or more, 2 μm, 4 μm, or 10 μm or less. When the average particle size of the second positive electrode active material precursor is within the above range, the reactivity with the first positive electrode active material precursor can be maximized.

[0051] The third positive electrode active material precursor may specifically be NiO, Co3O4, MnO2, ZrO2, Al2O3, or a combination thereof, in order to improve the low reactivity of the first positive electrode active material precursor.

[0052] According to the present invention, the third positive electrode active material precursor may be in the form of secondary particles, single particles, or amorphous.

[0053] According to the present invention, the third positive electrode active material precursor has an average particle size (D 50 The particle size may be 0.01 μm to 10 μm. Specifically, the third positive electrode active material precursor has an average particle size (D 50 The particle size of the third positive electrode active material precursor may be 0.01 μm, 0.1 μm, 1 μm or more, 2 μm, 4 μm, or 10 μm or less. When the average particle size of the third positive electrode active material precursor is within the above range, the reactivity with the first positive electrode active material precursor can be maximized.

[0054] According to the present invention, the positive electrode active material precursor may contain one or more selected from the second positive electrode active material precursor and the third positive electrode active material precursor in an amount of 0.5 to 5 parts by weight per 100 parts by weight of the first positive electrode active material precursor.

[0055] Method for manufacturing positive electrode active material The method for producing a positive electrode active material according to the present invention includes the step of mixing a positive electrode active material precursor and a lithium-containing raw material, and then firing them at a temperature of 700°C or higher but less than 830°C to obtain a lithium transition metal oxide in single-particle form. In the method for producing the positive electrode active material, a positive electrode active material doped with a doping element can be produced by mixing a doping element-containing raw material together with the positive electrode active material precursor and the lithium-containing raw material and firing them. Furthermore, in the method for producing the positive electrode active material, a positive electrode active material in which a coating layer is formed on the lithium transition metal oxide can be produced by mixing a coating element-containing raw material with the produced single-particle form lithium transition metal oxide and heat-treating it.

[0056] In conventional methods for producing positive electrode active materials using positive electrode active material precursors, high-temperature firing at 830°C or higher was required to obtain positive electrode active materials in single-particle form. However, according to the present invention, since a positive electrode active material precursor containing a first positive electrode active material precursor, which is a single-particle composite transition metal, and a transition metal hydroxide (second positive electrode active material precursor) and / or a transition metal oxide (third positive electrode active material precursor) is used during the production of the positive electrode active material, positive electrode active materials in single-particle form can be obtained even when fired at a low temperature of 700°C or higher but less than 830°C. In other words, positive electrode active materials in single-particle form can be obtained even when fired at a relatively low temperature of 700°C or higher but less than 830°C, instead of high-temperature firing at 830°C or higher.

[0057] The method for producing a positive electrode active material according to the present invention may include the steps of: further mixing the positive electrode active material precursor according to the present invention, a lithium-containing raw material, and selectively a doping element-containing raw material, and then performing primary calcination at a temperature of 700°C to less than 830°C to obtain a primary calcined product; and further mixing the primary calcined product, a lithium-containing raw material, and selectively a doping element-containing raw material, and then performing secondary calcination at a temperature of 700°C to 800°C to obtain a secondary calcined product. When calcination is performed in two steps, regions in which the crystallinity has deteriorated due to high-temperature calcination during primary calcination can be restored during secondary calcination.

[0058] The method for producing the positive electrode active material may further include the step of mixing the secondary calcined product with a coating element-containing raw material, then heat-treating it at a temperature of 500°C to 750°C to form a coating layer on a lithium transition metal oxide in single-particle form. When the method for producing the positive electrode active material further includes the coating layer formation step, it has the advantage that the deteriorated surface is further improved.

[0059] The lithium-containing raw material may include one or more selected from lithium hydroxide hydrate, lithium carbonate, lithium nitrate, and lithium oxide. Specifically, the lithium-containing raw material may be lithium hydroxide hydrate, and more specifically, LiOH·H2O. In this case, the reactivity between the precursor with a high atomic fraction of nickel among the metal elements in the precursor and the lithium-containing raw material can be improved.

[0060] During the production of the positive electrode active material, the positive electrode active material precursor and the lithium-containing raw material may be mixed such that the molar ratio (M:Li) of the transition metal (M (e.g., Ni+Co+Al, Ni+Co+Mn+Al)) contained in the positive electrode active material precursor to the lithium (Li) contained in the lithium-containing raw material is 1:1.02 to 1:1.2, specifically 1:1.02 to 1:1.1, and more specifically 1:1.02 to 1:1.07. In this case, the volume of the positive electrode active material produced is improved, and since unreacted Li does not remain as a byproduct, separation of positive electrode active material particles (induction of aggregation phenomenon of positive electrode active material) can be prevented after firing.

[0061] As described above, when firing is performed in two steps, in the primary firing step, the positive electrode active material precursor and the lithium-containing raw material may be mixed such that the molar ratio (M:Li) of the transition metal (M (e.g., Ni+Co+Al, Ni+Co+Mn+Al)) contained in the positive electrode active material precursor to the lithium (Li) contained in the lithium-containing raw material is 1:0.9 to 1:1.2, specifically 1:0.95 to 1:1.1, or more specifically 1:0.98 to 1:1.02. Then, in the secondary firing step, the primary firing product and the lithium-containing raw material may be mixed such that the molar ratio of the transition metal contained in the primary firing product to the lithium contained in the lithium-containing raw material is 1:0.01 to 1:0.1, specifically 1:0.01 to 1:0.07, or more specifically 1:0.03 to 1:0.05.

[0062] The firing temperature may be 700°C or higher and less than 830°C. Specifically, the firing temperature may be 700°C, 720°C, 750°C or higher, 820°C or lower, and less than 830°C. When the firing temperature is within the above range, the crystallinity of the particles is increased, Ni 2+ This suppresses the phenomenon of ions penetrating the Li layer, improving the conductivity of lithium ions. As a result, superior electrochemical properties can be achieved when applied to batteries.

[0063] The aforementioned firing may be carried out in an oxygen atmosphere. In this case, the reactivity is increased, the particles are fired uniformly, and the reduction of nickel is prevented, which is advantageous for the formation of an R-3m layered structure in the firing section. 3+ This allows for better maintenance of the positive electrode active material and increases its crystallinity.

[0064] The firing process may be carried out for 5 to 20 hours. Specifically, the firing process may be carried out for 8 hours, 10 hours, 15 hours or more, 16 hours, or 20 hours or less. When the firing time is within the above range, the lithium source reacts for a sufficient amount of time, increasing the degree of crystallinity through atomic rearrangement and reducing internal defects in single particles.

[0065] The positive electrode active material produced by the method for producing the positive electrode active material may have a composition represented by the following chemical formula 4 as a single-particle form of a lithium transition metal oxide.

[0066] [Chemical formula 4] Li x [Ni a4 M 1 b4 Mn c4 M 7 d4 O 2-y A y

[0067] In the chemical formula 4, M 1 is one or more elements selected from Co and Al, M 7 is one or more selected from B, Mg, Ca, Ti, V, Cr, Fe, Zn, Ga, Y, Zr, Nb, Mo, Ta, Sc, and W, A is one or more selected from F, Cl, Br, I, At, and S, 0.9 ≦ x ≦ 1.2, 0.6 ≦ a4 < 1, 0 < b4 ≦ 0.4, 0 ≦ c4 ≦ 0.4, 0 ≦ d4 ≦ 0.2, a4 + b4 + c4 + d4 = 1, 0 ≦ y ≦ 0.2.

[0068] The a4 means the atomic fraction of nickel among the metal elements excluding lithium in the positive electrode active material, and may be 0.6 ≦ a4 < 1, 0.6 ≦ a4 ≦ 0.98, or 0.7 ≦ a4 ≦ 0.95.

[0069] The b4 means the atomic fraction of the M 1 element among the metal elements excluding lithium in the positive electrode active material, and may be 0 < b4 ≦ 0.4, 0.01 ≦ b4 ≦ 0.4, or 0.01 ≦ b4 ≦ 0.3.

[0070] The c4 means the atomic fraction of manganese among the metal elements excluding lithium in the positive electrode active material, and may be 0 ≦ c4 ≦ 0.4, 0.01 ≦ c4 ≦ 0.4, or 0.01 ≦ c4 ≦ 0.3.

[0071] d4 represents the atomic fraction of the metal element excluding lithium in the positive electrode active material among M 7 element, and may be 0 ≦ d4 ≦ 0.2, 0 ≦ d4 ≦ 0.1, or 0 ≦ d4 ≦ 0.05.

[0072] According to the present invention, the positive electrode active material may contain nickel and cobalt. For example, it may have a composition represented by the following Chemical Formula 4-1.

[0073] [Chemical Formula 4-1] Li x [Ni a4 Co x’ Al y’ Mn c4 M 7 d4 O 2-y A y

[0074] In the Chemical Formula 4-1, M 7 is one or more selected from B, Mg, Ca, Ti, V, Cr, Fe, Zn, Ga, Y, Zr, Nb, Mo, Ta, Sc, and W, A is one or more selected from F, Cl, Br, I, At, and S, 0.9 ≦ x ≦ 1.2, 0.6 ≦ a4 < 1, 0 < x' ≦ 0.4, 0 ≦ y' ≦ 0.4, 0 ≦ c4 ≦ 0.4, 0 ≦ d4 ≦ 0.2, a4 + x' + y' + c4 + d4 = 1, 0 ≦ y ≦ 0.2.

[0075] According to the present invention, the positive electrode active material produced by the method for producing the positive electrode active material may be a single-particle form positive electrode active material having an average particle diameter (D 50 ) of 3 μm to 12 μm. Specifically, the positive electrode active material produced by the method for producing the positive electrode active material may have an average particle diameter (D 50 ) of 3 μm, 4 μm, 5 μm or more, 8 μm, 10 μm, 12 μm or less. In this case, the electrochemical characteristics of the battery including the positive electrode active material can be improved.

[0076] On the other hand, in the lithium transition metal oxide, lithium ions (Li+ When transition metal cations of similar size to ) are present, a phenomenon occurs in which the transition metal cations are mixed into the lithium layer, which is called cation mixing. In lithium nickel cobalt oxides, Ni 3+ Co 3+ Ions such as Li + Because of the large difference in size, the possibility of cation mixing occurring is low. However, among nickel ions, Ni has an oxidation state of +2. 2+ Because the ions have a similar size to lithium ions, cation mixing is likely to occur. Ni 2+ When ions are mixed in the lithium layer, the layered crystal structure cannot develop sufficiently, which reduces the structural stability of the active material, and the Ni present in the lithium layer 2+ Ions hinder the movement of lithium ions, leading to a decrease in battery performance. In particular, when the positive electrode active material is fired at a high temperature of 830°C or higher, the rate of phase transition from the stable LiNO2 layered structure to the NiO phase increases, and the degree of cation mixing tends to increase significantly. However, the positive electrode active material produced by the positive electrode active material production method of the present invention is fired at a temperature of less than 830°C to form single particles, and the above-mentioned phase transition can be suppressed. As a result, a positive electrode active material with a high degree of single particle formation, a low degree of cation mixing, and high crystallinity can be obtained. Specifically, the degree of cation mixing can be 1% or less. Therefore, a battery containing the positive electrode active material produced by the positive electrode active material production method can achieve excellent electrochemical performance.

[0077] positive electrode Furthermore, the present invention can provide a positive electrode for a lithium secondary battery containing a positive electrode active material manufactured by the method described above.

[0078] Specifically, the positive electrode includes a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector, the positive electrode active material being described above.

[0079] The positive electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and is conductive. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc. may be used. The positive electrode current collector usually has a thickness of 3 μm to 500 μm, and the adhesion strength of the positive electrode active material may be increased by forming fine irregularities on the surface of the current collector. For example, it can be used in various forms such as film, sheet, foil, mesh, porous material, foam, and nonwoven fabric.

[0080] The positive electrode active material layer may contain a conductive material and a binder together with the positive electrode active material.

[0081] The positive electrode active material may be included in an amount of 80% to 99% by weight, more specifically 85% to 98% by weight, relative to the total weight of the positive electrode active material layer. When included within the above content range, excellent capacity characteristics can be observed.

[0082] The conductive material is used to impart conductivity to the electrodes and is not particularly limited as long as it does not cause chemical changes in the battery it is used in. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. One of these may be used alone, or a mixture of two or more. The conductive material may be included in an amount of 1% to 30% by weight relative to the total weight of the positive electrode active material layer.

[0083] The binder plays a role in improving the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, of which one can be used alone or a mixture of two or more. The binder may be included in an amount of 1% to 30% by weight relative to the total weight of the positive electrode active material layer.

[0084] The positive electrode may be manufactured by a conventional method for manufacturing a positive electrode, except that the positive electrode active material described above is used. Specifically, it can be manufactured by coating a positive electrode active material layer-forming composition, which is prepared by dissolving or dispersing the positive electrode active material, and a binder and conductive material selectively in a solvent, onto a positive electrode current collector, followed by drying and rolling. In this case, the types and contents of the positive electrode active material, binder, and conductive material are as described above.

[0085] The solvent can be any solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. One of these can be used alone, or a mixture of two or more. The amount of solvent used should be sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, and to have a viscosity that allows for excellent thickness uniformity during subsequent coating for positive electrode manufacturing, taking into account the coating thickness and production yield of the active material layer forming composition.

[0086] Alternatively, the positive electrode may be manufactured by casting the positive electrode active material layer forming composition onto another support, peeling it off the support, and then laminating the resulting film onto the positive electrode current collector.

[0087] Lithium-ion rechargeable battery Furthermore, the present invention can be used to manufacture an electrochemical element including the positive electrode. The electrochemical element may be a battery, a capacitor, or more specifically, a lithium secondary battery.

[0088] The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, a separator interposed between the positive and negative electrodes, and an electrolyte. As the positive electrode is as described above, a detailed explanation will be omitted, and only the other components will be described in detail below.

[0089] Furthermore, the lithium secondary battery may selectively further include a battery container for housing the electrode assembly comprising the positive electrode, negative electrode, and separator, and a sealing member for sealing the battery container.

[0090] In the lithium secondary battery described above, the negative electrode includes a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0091] The negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. The negative electrode current collector usually has a thickness of 3 μm to 500 μm, and, similar to the positive electrode current collector, the bonding force of the negative electrode active material may be strengthened by forming fine irregularities on the surface of the current collector. For example, it can be used in various forms such as film, sheet, foil, mesh, porous material, foam, and nonwoven fabric.

[0092] The negative electrode active material layer selectively includes a binder and a conductive material together with the negative electrode active material.

[0093] As the negative electrode active material, compounds capable of reversible intercalation and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO2. β Examples include lithium-doped and dedoped metal oxides such as (0<β<2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites containing the metallic compound and carbonaceous material, such as Si-C composites or Sn-C composites; any one or more mixtures of these can be used. A metallic lithium thin film may also be used as the negative electrode active material. As for the carbon material, both low-crystallinity carbon and high-crystallinity carbon can be used. Typical examples of low-crystalline carbon include soft carbon and hard carbon, while typical examples of high-crystalline carbon include amorphous, plate-like, flaky, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0094] The negative electrode active material may be present in an amount of 80% to 99% by weight relative to the total weight of the negative electrode active material layer.

[0095] The binder is a component that helps to bond the conductive material, active material, and current collector, and is usually added in an amount of 0.1% to 10% by weight relative to the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0096] The conductive material is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10% by weight or less, specifically 5% by weight or less, relative to the total weight of the negative electrode active material layer. Such a conductive material is not particularly limited as long as it does not cause a chemical change in the battery and is conductive, and may be used, for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0097] The negative electrode active material layer may be manufactured by coating a negative electrode active material layer-forming composition, which is prepared by dissolving or dispersing a negative electrode active material and a binder and conductive material selectively in a solvent, onto a negative electrode current collector and then drying it; or it may be manufactured by casting the negative electrode active material layer-forming composition onto another support, peeling it off this support, and then laminating the resulting film onto the negative electrode current collector.

[0098] On the other hand, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without particular limitations, and those with low resistance to ion movement of the electrolyte and excellent electrolyte impregnation ability are particularly preferred. Specifically, porous polymer films, such as porous polymer films made from polyolefin polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or laminated structures of two or more layers thereof can be used. Alternatively, ordinary porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, coated separators containing ceramic components or polymeric substances may be used to ensure heat resistance or mechanical strength, and may be selectively used as single-layer or multi-layer structures.

[0099] Furthermore, the electrolytes used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0100] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0101] The organic solvent can be any solvent that can act as a medium through which ions involved in the electrochemical reaction of the battery can move, and is not particularly limited. Specifically, the organic solvents include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (propylene Carbonate solvents such as carbonate (PC); alcoholic solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, and may include a double-bonded aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, carbonate solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge and discharge performance of the battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred. In this case, the cyclic carbonate and the linear carbonate can be mixed in a volume ratio of about 1:1 to about 1:9 to produce an electrolyte with excellent performance.

[0102] The lithium salt can be any compound capable of providing lithium ions for use in lithium secondary batteries, and is not particularly limited. Specifically, the lithium salt can be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably within the range of 0.1M to 2.0M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, exhibiting excellent electrolyte performance and allowing lithium ions to move effectively.

[0103] In addition to the components of the electrolyte, the electrolyte may further contain one or more additives for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the additive may be present in an amount of 0.1% to 5% by weight relative to the total weight of the electrolyte.

[0104] As described above, the lithium secondary battery containing the positive electrode active material according to the present invention exhibits excellent discharge capacity, output characteristics, and life characteristics in a stable manner, making it useful in portable devices such as mobile phones, notebook computers, and digital cameras, as well as in the electric vehicle field, such as hybrid electric vehicles (HEVs).

[0105] This provides a battery module that includes the lithium secondary battery as a unit cell, and a battery pack that includes the same.

[0106] The aforementioned battery module or battery pack can be used as a power source for one or more medium-to-large devices, including power tools; electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems.

[0107] The external shape of the lithium secondary battery of the present invention is not particularly limited, but cylindrical, rectangular, pouch-type, or coin-type batteries using a can are possible.

[0108] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for small devices, but also suitably as a unit battery in medium- and large-sized battery modules containing a large number of battery cells. [Examples]

[0109] Hereinafter, embodiments of the present invention will be described in detail so that those with ordinary skill in the art to which the present invention pertains can easily implement it. However, the present invention can be realized in various different forms and is not limited to the embodiments described herein.

[0110] Examples and Comparative Examples Example 1 Ni 0.96 Co 0.04A cathode active material precursor was prepared containing 80 g of single-particle nickel-cobalt alloy (Avention) (first cathode active material precursor), 0.557 g of amorphous powder Al(OH)3 (DAEJOO KC) (second cathode active material precursor), and 0.162 g of amorphous powder ZrO2 (Guangdong Orient Zirconic Ind Sci&Tech Co.,Ltd) (third cathode active material precursor), along with 0.102 g of Y2O3 and 59.89 g of LiOH·H2O5. These were mixed so that the molar ratio of Ni+Co+Al:Li was 1:1, and the temperature was increased from room temperature to 810°C at a heating rate of 5°C / min. After that, primary calcination was performed at 810°C for 6 hours to obtain the primary calcined product.

[0111] 100g of the primary calcined product, 0.479g of Co(OH)2 (Huayou Cobalt), and 1.730g of LiOH·H2O were prepared and mixed so that the molar ratio of Ni+Co+Al:Li was 1:0.04. The temperature was raised from room temperature to 760°C at a heating rate of 5°C / min, and then secondary calcination was performed at 760°C for 9 hours to obtain the secondary calcined product.

[0112] The process involves mixing 100g of the aforementioned secondary calcined product, 1.940g of Co(OH)2 (Huayou Cobalt), and 0.145g of Al(OH)3 (DAEJOO KC), raising the temperature from room temperature to 700°C at a rate of 5°C / min, then heat-treating at 700°C for 3 hours, cooling to 500°C, and then heat-treating for another 3 hours, thereby producing a single-particle form of lithium transition metal oxide (Li[Ni]) containing a coating layer with Co and Al. 0.931 Co 0.060 Al 0.007 Zr 0.001 Y 0.001 O2 was manufactured.

[0113] For reference, Figure 1 shows the Ni 0.96 Co 0.04 The image shows an SEM image of a nickel-cobalt alloy (Avention) (first cathode active material precursor) in single-particle form, having the composition represented by [D]. The average particle size (D) of the first cathode active material precursor is shown. 50 The diameter is 3.09 μm.

[0114] Example 2 Ni 0.96 Co 0.04 A cathode active material precursor was prepared containing 80 g of single-particle nickel-cobalt alloy (Avention) (first cathode active material precursor) and 0.557 g of amorphous powder Al(OH)3 (DAEJOO KC) (second cathode active material precursor), having the composition represented by , along with 59.89 g of LiOH·H2O. The mixture was combined so that the molar ratio of Ni+Co+Al:Li was 1:1, and the temperature was increased from room temperature to 810°C at a heating rate of 5°C / min. After that, primary calcination was performed at 810°C for 6 hours to obtain the primary calcined product.

[0115] 100g of the primary calcined product and 1.730g of LiOH·H2O were prepared and mixed so that the molar ratio of Ni+Co+Al:Li was 1:0.04. The temperature was raised from room temperature to 760°C at a heating rate of 5°C / min, and then secondary calcination was performed at 760°C for 9 hours to obtain the secondary calcined product.

[0116] 100g of the aforementioned secondary calcined product is mixed with 1.940g of Co(OH)2 (Huayou Cobalt) and 0.145g of Al(OH)3 (DAEJOO KC). The temperature is raised from room temperature to 700°C at a rate of 5°C / min, followed by primary heat treatment at 700°C for 3 hours, then cooled to 500°C and further secondary heat treatment for 3 hours. This process results in a single-particle form lithium transition metal oxide (Li[Ni) containing a coating layer with Co and Al. 0.937 Co 0.056 Al 0.007 O2 was manufactured.

[0117] Example 3 Ni 0.96 Co 0.04A cathode active material precursor was prepared containing 80 g of single-particle nickel-cobalt alloy (Avention) (first cathode active material precursor) and 0.557 g of amorphous powder Al(OH)3 (DAEJOO KC) (second cathode active material precursor), having the composition represented by , along with 59.89 g of LiOH·H2O. The mixture was combined so that the molar ratio of Ni+Co+Al:Li was 1:1, and the temperature was increased from room temperature to 810°C at a heating rate of 5°C / min. After that, primary calcination was performed at 810°C for 6 hours to obtain the primary calcined product.

[0118] 100g of the primary calcined product, 0.479g of Co(OH)2 (Huayou Cobalt), and 1.730g of LiOH·H2O were prepared and mixed so that the molar ratio of Ni+Co+Al:Li was 1:0.04. The temperature was raised from room temperature to 760°C at a heating rate of 5°C / min, and then secondary calcination was performed at 760°C for 9 hours to obtain the secondary calcined product.

[0119] 100g of the aforementioned secondary calcined product, 1.940g of Co(OH)2 (Huayou Cobalt), and 0.145g of Al(OH)3 (DAEJOO KC) are mixed, the temperature is raised from room temperature to 700°C at a rate of 5°C / min, followed by primary heat treatment at 700°C for 3 hours, then the temperature is lowered to 500°C and secondary heat treatment is performed for another 3 hours, resulting in a single-particle form lithium transition metal oxide (Li[Ni) containing a coating layer with Co and Al. 0.933 Co 0.060 Al 0.007 O2 was manufactured.

[0120] Comparative Example 1 100g of spherical nickel-cobalt-manganese hydroxide (Huajin) with a Ni:Co:Mn molar ratio of 95:3:2, 0.424g of amorphous powder Al(OH)3 (DAEJOO KC), 0.203g of amorphous powder ZrO2 (Guangdong Orient Zirconic Ind Sci&Tech Co.,Ltd), 0.127g of Y2O3, and 5.52g of LiOH·H2O4 were prepared. These were mixed so that the Ni+Co+Mn+Al:Li molar ratio was 1:1. The temperature was increased from room temperature to 830°C at a heating rate of 5°C / min, and then primary calcination was performed at 830°C for 6 hours to obtain the primary calcined product.

[0121] 100g of the primary calcined product and 146g of LiOH·H2O2 were prepared and mixed so that the molar ratio of Ni+Co+Mn+Al:Li was 1:0.05. The temperature was raised from room temperature to 760°C at a heating rate of 5°C / min, and then secondary calcination was performed at 760°C for 9 hours to obtain the secondary calcined product.

[0122] 100g of the aforementioned secondary calcined product, 1.940g of Co(OH)2 (Huayou Cobalt), and 0.145g of Al(OH)3 (DAEJOO KC) are mixed, the temperature is raised from room temperature to 700°C at a rate of 5°C / min, followed by primary heat treatment at 700°C for 3 hours, then the temperature is lowered to 500°C and secondary heat treatment is performed for another 3 hours, resulting in a single-particle form lithium transition metal oxide (Li[Ni) containing a coating layer with Co and Al. 0.923 Co 0.049 Mn 0.019 Al 0.007 Zr 0.001 Y 0.001 O2 was manufactured.

[0123] For reference, Figure 2 shows an SEM image of spherical nickel-cobalt-manganese hydroxide (Huajin) with a Ni:Co:Mn molar ratio of 95:3:2. The average particle size (D) of the nickel-cobalt-manganese hydroxide (Huajin) is shown. 50 The thickness is 3.5 μm.

[0124] Comparative Example 2 100g of spherical nickel-cobalt-manganese oxide (LG Chem) with a Ni:Co:Mn molar ratio of 96:3:1, 0.526g of amorphous powder Al(OH)3 (DAEJOO KC), 0.203g of amorphous powder ZrO2 (Guangdong Orient Zirconic Ind Sci&Tech Co.,Ltd), 0.127g of Y2O3, and 6.486g of LiOH·H2O5 were prepared. These were mixed so that the Ni+Co+Mn+Al:Li molar ratio was 1:1. The temperature was increased from room temperature to 830°C at a heating rate of 5°C / min, and then primary calcination was performed at 830°C for 12 hours to obtain the primary calcined product.

[0125] 100g of the primary calcined product, 0.479g of Co(OH)2 (Huayou Cobalt), and 1.730g of LiOH·H2O were prepared and mixed so that the molar ratio of Ni+Co+Mn+Al:Li was 1:0.04. The temperature was raised from room temperature to 760°C at a heating rate of 5°C / min, and then secondary calcination was performed at 760°C for 12 hours to obtain the secondary calcined product.

[0126] 100g of the aforementioned secondary calcined product, 1.940g of Co(OH)2 (Huayou Cobalt), and 0.145g of Al(OH)3 (DAEJOO KC) are mixed, the temperature is raised from room temperature to 700°C at a rate of 5°C / min, followed by primary heat treatment at 700°C for 3 hours, then the temperature is lowered to 500°C and secondary heat treatment is performed for another 3 hours, resulting in a single-particle form lithium transition metal oxide (Li[Ni) containing a coating layer with Co and Al. 0.932 Co 0.049 Mn 0.01 Al 0.007 Zr 0.001 Y 0.001 O2 was manufactured.

[0127] For reference, Figure 3 shows an SEM image of spherical nickel-cobalt-manganese oxide (Avention) with a Ni:Co:Mn molar ratio of 96:3:1. The average particle size (D) of the nickel-cobalt-manganese oxide (Avention) is shown. 50 The diameter is 5.18 μm.

[0128] Experimental example Experimental Example 1: Analysis of cathode active material precursor and cathode active material Using a particle size analyzer (Microtrac, S3500, Diffractive index=1.55), volume cumulative particle size graphs were obtained for the first cathode active material precursor used in Examples 1-3 and the cathode active materials produced in Examples 1-3 and Comparative Examples 1 and 2. min , D 50 , D max The values ​​are shown in Table 1 below. Figure 4 is a volume cumulative particle size graph of the positive electrode active materials produced in Example 1, Comparative Examples 1 and 2.

[0129] Furthermore, SEM images of the positive electrode active materials produced in Example 1, Comparative Examples 1 and 2 were measured using a scanning electron microscope (JEOL Corporation) and are shown in Figure 5. Specifically, Figure 5(A) is the SEM image of the positive electrode active material produced in Example 1, Figure 5(B) is the SEM image of the positive electrode active material produced in Comparative Example 1, and Figure 5(C) is the SEM image of the positive electrode active material produced in Comparative Example 2.

[0130] Furthermore, XRD data for the cathode active materials produced in Example 1 and Comparative Example 1 were measured using XRD (Bruker, D8 Endeavor, Cu Target) and are shown in Figure 6. Referring to Figure 6, it can be confirmed that a layered cathode active material is produced even when the cathode active material precursor of Example 1 is mixed with a lithium-containing raw material and then calcined.

[0131] Furthermore, XRD data for the first and third cathode active material precursors used in Example 1 were measured using XRD (Bruker, D8 Endeavor, Cu Target) and are shown in Figure 7. Referring to Figure 7, it can be confirmed that the first cathode active material precursor has an Fm-3m space group, indicating an FCC (face-centered cubic structure), and that the third cathode active material precursor has a Cubic crystal structure with both Fm-3m and Fd-3m O2 (spinel type) space groups.

[0132] Furthermore, EDS data for the first cathode active material precursor used in Example 1 was measured using EDS (ThermoFisher, Quanta 250 FEG) and is shown in Figure 8. Referring to Figure 8, it can be confirmed that the alloy precursor in Example 1 is a metal mixture of Ni and Co.

[0133] [Table 1]

[0134] Experimental Example 2: Evaluation of Capacitance and Resistivity Characteristics Lithium secondary batteries were manufactured using the respective positive electrode active materials produced in the examples and comparative examples, and the initial charge capacity, initial discharge capacity, capacity retention rate, and resistance increase rate were evaluated for each lithium secondary battery.

[0135] The positive electrode active materials produced in the above examples and comparative examples, along with a conductive material (FX35) and a binder (PVdF), were mixed in a weight ratio of 95:2:3 in N-methyl-2-pyrrolidone (NMP) solvent to produce a positive electrode slurry. The positive electrode slurry was applied to one surface of an aluminum current collector, dried, and then rolled to produce a positive electrode. An electrode assembly was produced by interposing a separator between the positive electrode and Li metal, and after positioning it inside a battery case, an electrolyte was injected to produce a lithium secondary battery. In this case, the electrolyte used was an organic solvent in which ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate were mixed in a volume ratio of 3:3:4, to which 1M LiPF6 was dissolved.

[0136] Subsequently, each of the aforementioned secondary batteries was charged to 4.25V at 25°C with a constant current of 0.2C. Next, it was discharged to 2.5V with a constant current of 0.2C, and the initial charge capacity and initial discharge capacity were measured. The results are shown in Table 2 below.

[0137] The lithium secondary battery capacity was measured by repeating a charge-discharge cycle 50 times, charging with a constant current of 0.5C at 45℃ and in the range of 2.5~4.25V, and discharging with a constant current of 1C. In particular, the discharge capacity after 50 cycles (C) was compared to the discharge capacity after 1 cycle (C1). 50 ) Percentage (C 50 The capacity retention rate was defined as ( / C1 × 100), and this is shown in Table 2 below. Furthermore, for the first discharge cycle, DCIR(R1) was obtained by dividing the voltage drop (△V) over 60 seconds by the current, and for the 50th discharge cycle, DCIR(R 50 Percentage of (R 50 The resistance increase rate was defined as (R1 × 100), and this is shown in Table 2 below.

[0138] [Table 2]

[0139] Referring to Table 1 and Figure 5, the positive electrode active material produced using the positive electrode active material precursor according to the present invention has an average particle size (D 50 The size of the particles is large, and the degree of single particle formation is high. This indicates that the positive electrode active material precursor according to the present invention can be usefully used when manufacturing medium to large single particles. Furthermore, referring to Table 2, it can be confirmed that the positive electrode active materials of Examples 1 to 3 were manufactured by calcining the precursors at a relatively low temperature compared to the positive electrode active materials of Comparative Examples 1 and 2, yet single particles were formed well, and the battery performance was at an equivalent or superior level.

[0140] In conclusion, the positive electrode active material precursor according to the present invention is obtained by mixing a first positive electrode active material precursor containing a single-particle composite transition metal with a second positive electrode active material precursor and / or a third positive electrode active material precursor. Therefore, even if the positive electrode active material precursor is calcined at a relatively lower temperature than the temperature conventionally required to form single particles during the production of the positive electrode active material, a positive electrode active material in single-particle form can be obtained. Furthermore, the positive electrode active material produced by the method for producing the positive electrode active material according to the present invention can achieve excellent capacity characteristics, life characteristics, and resistance characteristics when applied to a secondary battery.

Claims

1. A first positive electrode active material precursor having the composition represented by the following chemical formula 1 and containing a single-particle composite transition metal, A positive electrode active material precursor comprising one or more selected from a second positive electrode active material precursor having a composition represented by the following chemical formula 2, and a third positive electrode active material precursor having a composition represented by the following chemical formula 3. [Chemical formula 1] Ni ａ１ M １ ｂ１ Mn ｃ１ M ２ ｄ１ In the aforementioned chemical formula 1, M １ is one or more selected from Co and Al, M ２ is one or more selected from Nb, Ti, Mg, Ta, Zr, Ca, Mo, V, Y, W, and Sc. 0.6 ≤ a1 < 1, 0 < b1 ≤ 0.4, 0 ≤ c1 ≤ 0.4, 0 ≤ d1 ≤ 0.2, [Chemical formula 2] M ３ ａ２ M ４ ｂ２ (OH) ｃ２ In the aforementioned chemical formula 2, M ３ is one or more selected from Ni, Co, Mn, Al, and Zr. M ４ is one or more selected from Nb, Ti, Mg, Ta, Ca, Mo, V, Y, W, and Sc. 0 < a² ≤ 1, 0 ≤ b² < 1, 2 ≤ c² ≤ 4, [Chemical formula 3] M ５ ａ３ M ６ ｂ３ O ｃ３ In the aforementioned chemical formula 3, M ５ is one or more selected from Ni, Co, Mn, Al, and Zr. M ６ is one or more selected from Nb, Ti, Mg, Ta, Ca, Mo, V, Y, W, and Sc. 0 < a3 ≤ 3, 0 ≤ b3 < 3, and 1 ≤ c3 ≤ 4.

2. The first positive electrode active material precursor has an average particle size (D ５０ The positive electrode active material precursor according to claim 1, wherein the size of the ) is 0.1 μm to 15 μm.

3. The positive electrode active material precursor according to claim 1, wherein the first positive electrode active material precursor has a face-centered cubic crystal structure.

4. The positive electrode active material precursor according to claim 1, wherein the second positive electrode active material precursor is in the form of secondary particles, single particles, or amorphous.

5. The second positive electrode active material precursor has an average particle size (D ５０ The positive electrode active material precursor according to claim 1, wherein the size of the ) is 0.01 μm to 10 μm.

6. The cathode active material precursor according to claim 1, wherein the third cathode active material precursor is in the form of secondary particles, single particles, or amorphous.

7. The third positive electrode active material precursor has an average particle size (D ５０ The positive electrode active material precursor according to claim 1, wherein the size of the ) is 0.01 μm to 10 μm.

8. The positive electrode active material precursor according to claim 1, wherein the positive electrode active material precursor comprises one or more selected from the second positive electrode active material precursor and the third positive electrode active material precursor in an amount of 0.5 to 5 parts by weight per 100 parts by weight of the first positive electrode active material precursor.

9. A method for producing a positive electrode active material, comprising the steps of mixing a positive electrode active material precursor according to any one of claims 1 to 8 with a lithium-containing raw material, and then firing the mixture at a temperature of 700°C or higher and less than 830°C to obtain a lithium transition metal oxide in single-particle form.

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