Positive electrode active material precursor, method for producing 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, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to 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. [Background technology]

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

[0004] LiCoO 2 Lithium cobalt oxide, such as LiNiO 2 Lithium nickel oxide, such as LiMnO 2 Or LiMn 2 O 4 Lithium manganese oxides such as LiFePO 4 Lithium transition metal oxides such as lithium iron phosphate oxides have been developed, and in recent years, Li[Ni a Co b Mn c ]O 2 , Li[Ni a Co b Al c ]O 2 , Li[Ni a Co b Mn c Al d ]O 2 As described above, lithium composite transition metal oxides containing two or more transition metals have been developed and are widely used.

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

[0006] When producing a lithium transition metal hydroxide as described above, a lithium transition metal hydroxide having a form of spherical secondary particles formed by aggregation of primary particles of several nm to several tens of nm is formed as a positive electrode active material precursor. In order to produce a positive electrode active material in a single particle form using this, a high-temperature heat treatment of 830°C or more is required.

[0007] However, when a high-temperature heat treatment of 830°C or higher is performed to produce a positive electrode active material in the form of a single particle, the layered structure of R-3m is not sufficiently maintained, and lithium passes through the crystal structure, causing a phase change to an Fm-3m rock-salt structure such as NiO, resulting in a decrease in the crystallinity of the positive electrode active material, which in turn causes problems such as a decrease in the capacity characteristics and life characteristics of a battery containing the positive electrode active material, and an increase in the rate of resistance increase. On the other hand, when a heat treatment is performed at a temperature lower than 830°C, the material exists in the form of over-baked secondary particles, which causes problems such as the improvement in life and gas generation not reaching the level expected for single particles.

[0008] Therefore, research is being conducted to develop a positive electrode active material precursor that does not require high-temperature heat treatment of 830° C. or more to increase the crystallinity of the positive electrode active material during the production of the single-particle positive electrode active material. Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a positive electrode active material precursor that can realize a positive electrode active material in a single particle form even when fired at a low temperature.

[0010] Another object of the present invention is to provide a method for producing a positive electrode active material, which can provide a positive electrode active material in the form of a single particle even when fired at a low temperature by using the positive electrode active material precursor in the production of the positive electrode active material. [Means for solving the problem]

[0011] In order 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 positive electrode active material precursor including one or more selected from a first positive electrode active material precursor having a composition represented by the following chemical formula 1 and including a composite transition metal in a single particle form, 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:

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

[0014] In the above 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であり、 [Chemical formula 2] M 3 a2 M 4 b2 (OH) c2 In the above 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 above 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) In the present invention, the first positive electrode active material precursor has an average particle size (D 50 ) is 0.1 μm to 15 μm.

[0016] (3) The present invention provides the positive electrode active material precursor according to (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 the 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 has an amorphous form.

[0018] (5) In the present invention, the second positive electrode active material precursor has an average particle size (D 50 ) is 0.01 μm to 10 μm.

[0019] (6) The present invention provides the 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 has an irregular shape.

[0020] (7) In the present invention, the third positive electrode active material precursor has an average particle size (D 50 ) is 0.01 μm to 10 μm.

[0021] (8) The present invention provides the positive electrode active material precursor according to any one of (1) to (7), wherein the positive electrode active material precursor contains 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, the method including the steps of mixing the positive electrode active material precursor according to any one of (1) to (8) above with a lithium-containing raw material, and then calcining the mixture at a temperature of 700° C. or higher and lower than 830° C. to obtain a lithium transition metal oxide in a single particle form.

[0023] (10) The present invention relates to a method for producing a granular material having an average particle diameter (D 50 ) is 3 μm to 12 μm.

[0024] (11) The present invention provides a method for determining the average particle size (D 50 ) is 4 μm to 8 μm. Effect of the Invention

[0025] The positive electrode active material precursor according to the present invention uses a mixture of a first positive electrode active material precursor containing a composite transition metal in a single particle form, and 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 fired at a temperature relatively lower than the temperature conventionally required for forming single particles during production of the positive electrode active material, a positive electrode active material in a single particle form can be obtained.

[0026] The positive electrode active material produced by the method for producing a positive electrode active material according to the present invention can achieve excellent capacity characteristics, life characteristics, and resistance characteristics, as well as a significant effect of reducing gas generation, when applied to a secondary battery. [Brief description of the drawings]

[0027] [Figure 1] 2 is an SEM image of a first positive electrode active material precursor used in Example 1. [Diagram 2] 1 is a SEM image of the nickel cobalt manganese hydroxide used in Comparative Example 1. [Diagram 3] 1 is an SEM image of the nickel-cobalt-manganese oxide used in Comparative Example 2. [Figure 4] 2 is a graph showing the volume-accumulated particle size of the positive electrode active materials prepared in Example 1 and Comparative Examples 1 and 2. [Diagram 5] 1 shows SEM images of the positive electrode active materials produced in (A) Example 1, (B) Comparative Example 1, and (C) Comparative Example 2. [Figure 6] 1 shows XRD data of the positive electrode active materials produced in Example 1 and Comparative Example 1. [Figure 7] 3 shows XRD data of a first positive electrode active material precursor and a third positive electrode active material precursor used in Example 1. [Figure 8] 1 shows EDS data of the first positive electrode active material precursor used in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0029] As used herein, terms such as "comprise," "comprise," or "have" are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, but should not be understood as precluding the presence or additional possibility of one or more other features, numbers, steps, components, or combinations thereof.

[0030] In this specification, the average particle size (D 50 ) means the particle size at 50% of the volume cumulative particle size distribution of the positive electrode active material precursor, the positive electrode active material, or the lithium transition metal oxide powder. 50 ) can be measured by a laser diffraction method. For example, the positive electrode active material powder is dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), and ultrasonic waves of about 28 kHz are irradiated at an output of 60 W, and a volume cumulative particle size distribution graph is obtained, and the particle size corresponding to 50% of the volume cumulative amount is obtained.

[0031] In this specification, the term "on" is meant to include not only the case where one structure is formed directly on top of another structure, but also the case where a third structure is interposed between the structures.

[0032] In this specification, the term "single particle form" refers to a concept that is contrasted with the spherical secondary particle form formed by aggregation of tens to hundreds of primary particles produced by conventional methods, and may include a form in which particles are separated and / or dispersed from each other so as to form an independent and / or separate phase for each particle, or a form in which 2 to 10 particles or 2 to 5 particles are attached to each other.

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

[0034] Positive electrode active material precursor The positive electrode active material precursor according to the present invention has a composition represented by Chemical Formula 1 below and includes one or more selected from a first positive electrode active material precursor including a composite transition metal in a single particle form, a second positive electrode active material precursor having a composition represented by Chemical Formula 2 below, and a third positive electrode active material precursor having a composition represented by Chemical Formula 3 below.

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

[0036] In the above 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であり、 [Chemical formula 2] M 3 a2 M 4 b2 (OH) c2 In the above 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 above 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 present inventors conducted extensive research to develop a positive electrode active material that can achieve excellent life characteristics and resistance characteristics. As a result, they discovered that when a first positive electrode active material precursor, which is a composite transition metal in a single particle form, is mixed with a transition metal hydroxide and / or a transition metal oxide and used as a positive electrode active material precursor, a positive electrode active material with a high degree of single particle size that can achieve excellent life characteristics and resistance characteristics even when fired at a relatively low temperature can be produced, and thus completed the present invention.

[0038] First, when using a conventional cathode active material precursor having the form of secondary particles formed by agglomeration of primary particles, high-temperature firing at 830° C. or more is required to produce a cathode active material in a single particle form, whereas when using a cathode active material precursor containing a first cathode active material precursor, which is a composite transition metal in a single particle form, and a transition metal hydroxide (second cathode active material precursor) and / or a transition metal oxide (third cathode active material precursor) as in the present invention, there is an advantage that a cathode active material in a single particle form can be produced even by firing at less than 830° C. As a result, there is no phase change of the NiO phase to a rock salt structure, which can occur when high-temperature firing at 830° C. or more occurs, and as a result, a cathode active material with excellent performance can be produced.

[0039] Furthermore, since 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 a composite transition metal in a single particle form having a composition represented by Chemical Formula 1. Meanwhile, the first positive electrode active material precursor may be a composite transition metal in a single particle form having a composition represented by Chemical Formula 1 below, the surface of which is modified with an oxide, a hydrate, or the like by reacting with oxygen or moisture in the air.

[0041] In the above Chemical Formula 1, The a1 refers to 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. The b1 is M among the metal elements in the first positive electrode active material precursor. 1 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 c1 refers to 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 d1 is M among the metal elements in the first positive electrode active material precursor. 2 It means 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, and may have a composition represented by the following 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 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] Meanwhile, the first positive electrode active material precursor may be a composite transition metal in a single particle form having a composition represented by the following Chemical Formula 1. The first positive electrode active material precursor may be a composite transition metal in a single particle form having a composition represented by the following Chemical Formula 1, the surface of which is modified with an oxide, a hydrate, or the like by reacting with oxygen or moisture in the air.

[0046] According to the present invention, the first positive electrode active material precursor has an average particle size (D 50 Specifically, the first positive electrode active material precursor may have an average particle size (D 50 ) may be 0.1 μm, 2 μm, 3 μm, 5 μm or more, and 10 μm, 12 μm, 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, thereby enabling the display of high capacity and output characteristics.

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

[0048] The second positive electrode active material precursor is Ni(OH) 2 , Co(OH) 2 , Zr(OH) 4 , Al(OH) 3 , or a combination thereof.

[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 50Specifically, the second positive electrode active material precursor may have an average particle size (D 50 ) may be 0.01 μm, 0.1 μm, 1 μm or more, and 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 is specifically selected from NiO, Co in order to improve the low reactivity of the first positive electrode active material precursor. 3 O 4 , MnO 2 , ZrO 2 , Al 2 O 3 , or a combination thereof.

[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 Specifically, the third positive electrode active material precursor may have an average particle size (D 50 ) may be 0.01 μm, 0.1 μm, 1 μm or more, and 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 include 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 based on 100 parts by weight of the first positive electrode active material precursor.

[0055] Method for producing positive electrode active material The method for producing a positive electrode active material according to the present invention includes a step of mixing a positive electrode active material precursor according to the present invention with a lithium-containing raw material, and then calcining the mixture at a temperature of 700° C. or more and less than 830° C. to obtain a lithium transition metal oxide in a single particle form. The method for producing a positive electrode active material may produce a positive electrode active material doped with a doping element by mixing a doping element-containing raw material with the positive electrode active material precursor and the lithium-containing raw material and calcining the mixture. The method for producing a positive electrode active material may also produce a positive electrode active material having a coating layer formed on the lithium transition metal oxide by mixing a coating element-containing raw material with the produced single particle form lithium transition metal oxide and heat treating the mixture.

[0056] In the conventional method for producing a positive electrode active material using a positive electrode active material precursor, high-temperature firing at 830°C or higher was required to obtain a positive electrode active material in a single particle form. However, according to the present invention, a positive electrode active material precursor containing a first positive electrode active material precursor, which is a composite transition metal in a 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) is used during the production of the positive electrode active material, so that a positive electrode active material in a single particle form can be obtained even if it is fired at a low temperature of 700°C or higher and lower than 830°C. In other words, a positive electrode active material in a single particle form can be obtained even if it is fired at a relatively low temperature of 700°C or higher and lower than 830°C, rather than at a high temperature of 830°C or higher.

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

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

[0059] The lithium-containing raw material may include at least one selected from lithium hydroxide hydrate, lithium carbonate, lithium nitrate, and lithium oxide. The lithium-containing raw material may be specifically lithium hydroxide hydrate, more specifically LiOH·H 2 In this case, the reactivity of the precursor having a high atomic fraction of nickel among the metal elements in the precursor with the lithium-containing raw material can be improved.

[0060] When preparing the positive electrode active material, the positive electrode active material precursor and the lithium-containing raw material may be mixed so 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, more specifically 1:1.02 to 1:1.07. In this case, the capacity of the prepared positive electrode active material is improved, and unreacted Li does not remain as a by-product, so that separation of the positive electrode active material particles (induction of agglomeration phenomenon of the positive electrode active material) does not occur after firing.

[0061] When the calcination is performed in two steps as described above, in the first calcination step, the positive electrode active material precursor and the lithium-containing raw material may be mixed so 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, more specifically 1:0.98 to 1:1.02. Then, in the second calcination step, the primary calcination product and the lithium-containing raw material may be mixed so that the molar ratio of the transition metal contained in the primary calcination 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, more specifically 1:0.03 to 1:0.05.

[0062] The sintering temperature may be 700° C. or more and less than 830° C. Specifically, the sintering temperature may be 700° C., 720° C., or 750° C. or more and 820° C. or less and less than 830° C. When the sintering temperature is within the above range, the crystallinity of the particles is increased, and Ni 2+ This suppresses the phenomenon of ions penetrating into the Li layer and improves the conductivity of lithium ions, which can lead to excellent electrochemical properties when applied to batteries.

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

[0064] The calcination may be performed for 5 to 20 hours. Specifically, the calcination may be performed for 8, 10, or 15 hours or more, or 16 or 20 hours or less. When the calcination time is within the above range, the lithium source reacts for a sufficient time to increase the crystallinity due to the rearrangement of atoms, and there is an effect of reducing internal defects of single particles.

[0065] The positive electrode active material produced by the method for producing the positive electrode active material may be a lithium transition metal oxide in a single particle form, and may have a composition represented by the following Chemical Formula 4.

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

[0067] In the above 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である。

[0068] The a4 means the atomic fraction of nickel among 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 is M among the metal elements other than lithium in the positive electrode active material. 1 means the atomic fraction of an element, 0 <b4≦0.4、0.01≦b4≦0.4、または0.01≦b4≦0.3であってよい。

[0070] The c4 means the atomic fraction of manganese among 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] The d4 is M among the metal elements other than lithium in the positive electrode active material. 7 It means the atomic fraction of an 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 include nickel and cobalt, and may have a composition represented by the following 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 above 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である。

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

[0076] On the other hand, lithium ions (Li+ When transition metal cations of similar size to the lithium layer are present, the transition metal cations are mixed into the lithium layer, which is called cation mixing. In lithium nickel cobalt oxide, Ni 3+ , Co 3+ Ions such as Li + Since the size difference between them is large, the possibility of cation mixing occurring is low. However, the nickel ion, which has an oxidation number of +2, Ni 2+ The ions have a similar size to the lithium ion, so cation mixing is likely to occur. 2+ When Ni ions are mixed in the lithium layer, the layered crystal structure cannot develop sufficiently, so the structural stability of the active material decreases, and the Ni 2+ The ions prevent the movement of lithium ions, which reduces battery performance. In particular, when the positive electrode active material is sintered at high temperatures of 830°C or higher, stable LiNO 2 The rate of phase change from the layered structure of NiO to NiO phase increases, and the degree of cation mixing tends to increase significantly. However, the positive electrode active material manufactured by the method for manufacturing a positive electrode active material of the present invention is sintered at a temperature of less than 830°C to form single particles, and the above-mentioned phase change can be suppressed, so that a positive electrode active material having 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. As a result, a battery including the positive electrode active material manufactured by the method for manufacturing a positive electrode active material can achieve excellent electrochemical performance.

[0077] positive electrode The present invention also provides a positive electrode for a lithium secondary battery, which contains the positive electrode active material produced by the above-mentioned method.

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

[0079] The positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity, and may be, for example, stainless steel, aluminum, nickel, titanium, baked carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. The positive electrode current collector usually has a thickness of 3 μm to 500 μm, and the adhesive 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 a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

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

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

[0082] The conductive material is used to impart conductivity to the electrode, and can be used without any particular limitation as long as it does not cause a chemical change in the battery and has electronic conductivity. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fibers; 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; and conductive polymers such as polyphenylene derivatives, and one of these may be used alone or a mixture of two or more of them may be used. The conductive material may be contained in an amount of 1% by weight to 30% by weight based on the total weight of the positive electrode active material layer.

[0083] The binder plays a role of improving the adhesion between the positive electrode active material particles and the adhesive strength 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, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these can be used alone or a mixture of two or more can be used. The binder may be contained in an amount of 1% by weight to 30% by weight based on the total weight of the positive electrode active material layer.

[0084] The positive electrode may be manufactured by a typical method for manufacturing a positive electrode, except for using the positive electrode active material. Specifically, the positive electrode may be manufactured by applying a composition for forming a positive electrode active material layer, which is prepared by dissolving or dispersing the positive electrode active material and, optionally, a binder and a conductive material 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 may be any solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one or more of these may be used alone or in combination. The amount of the solvent used may be sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, and to provide a viscosity that allows excellent thickness uniformity during subsequent application for the manufacture of a positive electrode, taking into consideration the coating thickness and manufacturing yield of the active material layer-forming composition.

[0086] As another method, the positive electrode may be produced by casting the composition for forming a positive electrode active material layer on another support, peeling the composition from the support, and laminating the resulting film on a positive electrode current collector.

[0087] Lithium secondary battery The present invention also provides an electrochemical device including the positive electrode, which may be, for example, a battery or a capacitor, and more specifically, a lithium secondary battery.

[0088] Specifically, the lithium secondary battery includes a positive electrode, a negative electrode facing the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. The positive electrode is as described above, so a detailed description is omitted, and only the other components are specifically described below.

[0089] Also, the lithium secondary battery may optionally further include a battery container that houses an electrode assembly of the positive electrode, the negative electrode, and a separator, and a sealing member that seals the battery container.

[0090] In the lithium secondary battery, 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 a chemical change in the battery and has high conductivity, and may be, for example, copper, stainless steel, aluminum, nickel, titanium, baked carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, or aluminum-cadmium alloy. The negative electrode current collector usually has a thickness of 3 μm to 500 μm, and may be formed with fine irregularities on the surface of the current collector in the same manner as the positive electrode current collector to strengthen the binding force of the negative electrode active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, or nonwoven fabric.

[0092] The negative electrode active material layer includes a negative electrode active material, and optionally a binder and a conductive material.

[0093] The negative electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium. Specific examples of the negative electrode active material 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, and Al alloys; SiO β (0<β<2), SnO 2 , vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the metallic compounds and carbonaceous materials, such as Si-C composites and Sn-C composites, and any one or a mixture of two or more of these can be used. In addition, a metallic lithium thin film can be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon can be used as the carbon material. Representative examples of low crystalline carbon include soft carbon and hard carbon, and representative examples of high crystalline carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature fired carbon such as petroleum or coal tar pitch derived cokes.

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

[0095] The binder is a component that aids in bonding between the conductive material, the active material, and the current collector, and is usually added in an amount of 0.1% by weight to 10% by weight based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, 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, based on 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 has conductivity, and examples of such conductive materials include graphite such as natural graphite and 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 produced by applying a composition for forming a negative electrode active material layer, which is produced by dissolving or dispersing a negative electrode active material, and optionally a binder and a conductive material, in a solvent, onto a negative electrode current collector and drying the composition. Alternatively, the negative electrode active material layer may be produced by casting the composition for forming a negative electrode active material layer onto another support, peeling it off from the support, and laminating the resulting film onto the negative electrode current collector.

[0098] Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a path for lithium ions to move. Any separator that is generally used in lithium secondary batteries can be used without any particular limitation, and in particular, a separator that has low resistance to ion movement of the electrolyte and has excellent electrolyte impregnation ability is preferred. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof can be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting glass fiber, polyethylene terephthalate fiber, etc., may be used. In addition, in order to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymeric substance may be used, and may be selectively used as a single layer or multilayer structure.

[0099] In addition, examples of the electrolyte used in the present invention include 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 production of lithium secondary batteries, but are not limited to these.

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

[0101] The organic solvent can be used without any particular limitation as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent can be an ester solvent such as methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, etc.; an ether solvent such as dibutyl ether or tetrahydrofuran, etc.; a ketone solvent such as cyclohexanone, etc.; an aromatic hydrocarbon solvent such as benzene or fluorobenzene, etc.; dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate (propylene carbonate), etc. Examples of suitable solvents include carbonate-based solvents such as ethylene carbonate (PC), alcohol-based solvents such as ethyl alcohol and isopropyl alcohol, nitriles such as R-CN (R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, which may contain a double bond aromatic ring or an ether bond), amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, and sulfolanes. Among these, carbonate-based 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 enhance the charge / discharge performance of a 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 chain carbonate are mixed in a volume ratio of about 1:1 to about 1:9 to provide an excellent electrolyte performance.

[0102] The lithium salt can be any compound that can provide lithium ions used in lithium secondary batteries without any particular limitation. Specifically, the lithium salt can be LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAlO 4 , LiAlCl 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN(C 2 F 5 SO 3 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ) 2 , LiCl, LiI, or LiB(C 2 O 4 ) 2 etc. may be used. The concentration of the lithium salt is preferably within the range of 0.1 M to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, and therefore can exhibit excellent electrolyte performance and can effectively move lithium ions.

[0103] In addition to the constituents of the electrolyte, the electrolyte may further contain one or more additives such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinoneimine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing the decrease in battery capacity, improving the discharge capacity of the battery, etc. In this case, the additives may be contained in an amount of 0.1% by weight to 5% by weight based on the total weight of the electrolyte.

[0104] As described above, the lithium secondary battery including the positive electrode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and life characteristics, and is therefore useful in portable devices such as mobile phones, notebook computers, and digital cameras, and in the field of electric vehicles such as hybrid electric vehicles (HEVs).

[0105] Thereby, a battery module including the lithium secondary battery as a unit cell, and a battery pack including the same are provided.

[0106] The battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0107] The external shape of the lithium secondary battery of the present invention is not particularly limited, and may be a cylindrical shape using a can, a square shape, a pouch shape, a coin shape, or the like.

[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 a medium- to large-sized battery module containing a large number of battery cells. EXAMPLES

[0109] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: FIG. 1 is a block diagram of a semiconductor device according to an embodiment of the present invention;

[0110] Examples and Comparative Examples Example 1 Ni 0.96 Co 0.04 The composition is represented by the formula: 80 g of a nickel-cobalt alloy (Avention) in the form of a single particle (first positive electrode active material precursor), 80 g of amorphous powdered Al(OH) 3 (DAEJOO KC) (second positive electrode active material precursor) 0.557 g, and amorphous powdered ZrO 2 (Guangdong Orient Zirconic Ind Sci&Tech Co.,Ltd) (third positive electrode active material precursor) 0.162g of positive electrode active material precursor, Y 2 O 3 0.102g, and LiOH H 2 59.89 g of O was prepared and mixed so that the molar ratio of Ni+Co+Al:Li was 1:1. The temperature was raised from room temperature to 810°C at a heating rate of 5°C / min, and then the mixture was fired at 810°C for 6 hours to obtain a fired product.

[0111] 100g of the first calcined product, Co(OH) 2 (Huayou Cobalt) 0.479g, LiOH·H 2 1.730 g of O was 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 the mixture was subjected to secondary firing at 760°C for 9 hours to obtain a secondary fired product.

[0112] 100 g of the second calcined product, Co(OH) 2 (Huayou Cobalt Co., Ltd.) 1.940g, and Al(OH) 3 (DAEJOO KC) 0.145g was mixed and the temperature was raised from room temperature to 700℃ at a heating rate of 5℃ / min, followed by heat treatment at 700℃ for 3 hours, and then the temperature was lowered to 500℃ and heat treatment for another 3 hours. This resulted in the formation of a lithium transition metal oxide (Li[Ni 0.931 Co 0.060 Al 0.007 Zr 0.001 Y 0.001 ]O 2 ) was manufactured.

[0113] For reference, FIG. 0.96 Co 0.04 The first positive electrode active material precursor has a composition represented by the formula: 50 ) is 3.09 μm.

[0114] Example 2 Ni 0.96 Co 0.04 80 g of a nickel-cobalt alloy (Avention) (first positive electrode active material precursor) in the form of a single particle, and 80 g of amorphous powdered Al(OH) 3 (DAEJOO KC) (second positive electrode active material precursor) 0.557 g, and LiOH H 2 59.89 g of O was prepared and mixed so that the molar ratio of Ni+Co+Al:Li was 1:1. The temperature was raised from room temperature to 810°C at a heating rate of 5°C / min, and then the mixture was fired at 810°C for 6 hours to obtain a fired product.

[0115] 100 g of the first calcined product and LiOH H 2 1.730 g of O was 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 the mixture was subjected to secondary firing at 760°C for 9 hours to obtain a secondary fired product.

[0116] 100 g of the secondary calcined product and Co(OH) 2 (Huayou Cobalt) 1.940g, Al(OH) 3 (DAEJOO KC) 0.145g was mixed and the temperature was raised from room temperature to 700℃ at a heating rate of 5℃ / min. Then, the primary heat treatment was performed at 700℃ for 3 hours, and the temperature was lowered to 500℃ and the secondary heat treatment was performed for another 3 hours. This resulted in the formation of a lithium transition metal oxide (Li[Ni 0.937 Co 0.056 Al 0.007 ]O 2 ) was manufactured.

[0117] Example 3 Ni 0.96 Co 0.04 80 g of a nickel-cobalt alloy (Avention) (first positive electrode active material precursor) in the form of a single particle, and 80 g of amorphous powdered Al(OH) 3 (DAEJOO KC) (second positive electrode active material precursor) 0.557 g, and LiOH H 2 59.89 g of O was prepared and mixed so that the molar ratio of Ni+Co+Al:Li was 1:1. The temperature was raised from room temperature to 810°C at a heating rate of 5°C / min, and then the mixture was fired at 810°C for 6 hours to obtain a fired product.

[0118] 100g of the first calcined product, Co(OH) 2 (Huayou Cobalt) 0.479g, LiOH·H 2 1.730 g of O was 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 the mixture was subjected to secondary firing at 760°C for 9 hours to obtain a secondary fired product.

[0119] 100 g of the second calcined product, Co(OH) 2 (Huayou Cobalt Co., Ltd.) 1.940g, and Al(OH) 3(DAEJOO KC) 0.145g was mixed and the temperature was raised from room temperature to 700℃ at a heating rate of 5℃ / min. Then, the primary heat treatment was performed at 700℃ for 3 hours, and the temperature was lowered to 500℃ and the secondary heat treatment was performed for another 3 hours. This resulted in the formation of a lithium transition metal oxide (Li[Ni 0.933 Co 0.060 Al 0.007 ]O 2 ) was manufactured.

[0120] Comparative Example 1 100 g of spherical nickel cobalt manganese hydroxide (Huajin) with a molar ratio of Ni:Co:Mn of 95:3:2, and amorphous powdered Al(OH) 3 (DAEJOO KC) 0.424g, amorphous powdered ZrO 2 (Guangdong Orient Zirconic Ind Sci&Tech Co., Ltd)0.203g, Y 2 O 3 0.127g, and LiOH H 2 45.52 g of O was prepared and mixed so that the molar ratio of Ni+Co+Mn+Al:Li was 1:1. The temperature was raised from room temperature to 830°C at a heating rate of 5°C / min, and then the mixture was fired at 830°C for 6 hours to obtain a fired product.

[0121] 100 g of the first calcined product and LiOH H 2 2.146 g of O was 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 the mixture was subjected to secondary firing at 760°C for 9 hours to obtain a secondary fired product.

[0122] 100 g of the second calcined product, Co(OH) 2 (Huayou Cobalt Co., Ltd.) 1.940g, and Al(OH) 3(DAEJOO KC) 0.145g was mixed and the temperature was raised from room temperature to 700℃ at a heating rate of 5℃ / min. Then, the primary heat treatment was performed at 700℃ for 3 hours, and the temperature was lowered to 500℃ and the secondary heat treatment was performed for another 3 hours. This resulted in the formation of a lithium transition metal oxide (Li[Ni 0.923 Co 0.049 Mn 0.019 Al 0.007 Zr 0.001 Y 0.001 ]O 2 ) was manufactured.

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

[0124] Comparative Example 2 100 g of spherical nickel cobalt manganese oxide (LG Chem) with a molar ratio of Ni:Co:Mn of 96:3:1, and amorphous powdered Al(OH) 3 (DAEJOO KC) 0.526g, amorphous powdered ZrO 2 (Guangdong Orient Zirconic Ind Sci&Tech Co., Ltd)0.203g, Y 2 O 3 0.127g, and LiOH H 2 56.486 g of O was prepared and mixed so that the molar ratio of Ni+Co+Mn+Al:Li was 1:1. The temperature was raised from room temperature to 830°C at a heating rate of 5°C / min, and then the mixture was fired at 830°C for 12 hours to obtain a fired product.

[0125] 100g of the first calcined product, Co(OH) 2 (Huayou Cobalt Co., Ltd.) 0.479 g, and LiOH H 21.730 g of O was 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 the mixture was subjected to secondary firing at 760°C for 12 hours to obtain a secondary fired product.

[0126] 100 g of the second calcined product, Co(OH) 2 (Huayou Cobalt Co., Ltd.) 1.940g, and Al(OH) 3 (DAEJOO KC) 0.145g was mixed and the temperature was raised from room temperature to 700℃ at a heating rate of 5℃ / min. Then, the primary heat treatment was performed at 700℃ for 3 hours, and the temperature was lowered to 500℃ and the secondary heat treatment was performed for another 3 hours. This resulted in the formation of a lithium transition metal oxide (Li[Ni 0.932 Co 0.049 Mn 0.01 Al 0.007 Zr 0.001 Y 0.001 ]O 2 ) was manufactured.

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

[0128] Experimental Example Experimental Example 1: Analysis of Positive Electrode Active Material Precursor and Positive Electrode Active Material A particle size measurement device (Microtrac, S3500, Diffractive index = 1.55) was used to obtain a volume cumulative particle size graph of the first positive electrode active material precursor used in Examples 1 to 3 and the positive electrode active materials produced in Examples 1 to 3 and Comparative Examples 1 and 2. min , D 50 , D max The values ​​are shown in the following Table 1. FIG. 4 is a graph showing the volume cumulative particle size of the positive electrode active materials prepared in Example 1 and Comparative Examples 1 and 2.

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

[0130] In addition, the XRD data of the positive electrode active materials prepared 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 seen that a layered positive electrode active material was prepared even when the positive electrode active material precursor of Example 1 was mixed with a lithium-containing raw material and then fired.

[0131] In addition, the XRD data of the first and third positive electrode active material precursors used in Example 1 were measured using an XRD (Bruker, D8 Endeavor, Cu Target), and are shown in FIG. 7. Referring to FIG. 7, it was confirmed that the first positive electrode active material precursor has a space group of Fm-3m and thus has a face-centered cubic structure (FCC), and the third positive electrode active material precursor has a space group of Fm-3m and Fd-3m O. 2 It can be confirmed that both have cubic crystal structures with the (spinel type) space group.

[0132] In addition, EDS data of the first positive electrode active material precursor used in Example 1 was measured using an EDS (ThermoFisher, Quanta 250 FEG) and is shown in Fig. 8. Referring to Fig. 8, it can be seen that the alloy precursor in Example 1 is a metal in which Ni and Co are mixed.

[0133] [Table 1]

[0134] Experimental example 2: Evaluation of capacitance and resistance characteristics Lithium secondary batteries were produced using the positive electrode active materials produced in each of the Examples and Comparative Examples, and the initial charge capacity, initial discharge capacity, capacity retention rate, and resistance increase rate of each lithium secondary battery were evaluated.

[0135] The positive electrode active materials prepared in the examples and comparative examples, 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 prepare a positive electrode slurry. The positive electrode slurry was applied to one side of an aluminum current collector, dried, and rolled to prepare a positive electrode. An electrode assembly was prepared by interposing a separator between the positive electrode and Li metal, and placed inside a battery case, and an electrolyte was injected to prepare a lithium secondary battery. In this case, the electrolyte was prepared by dissolving 1M LiPF in an organic solvent in which ethylene carbonate: ethyl methyl carbonate: diethyl carbonate were mixed in a volume ratio of 3:3:4. 6 The electrolyte used was a solution of

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

[0137] The capacity of the lithium secondary battery was measured by repeating a charge-discharge cycle of charging at a constant current of 0.5 C in the range of 2.5 to 4.25 V at 45° C. and discharging at a constant current of 1 C 50 times. 1 ) vs. 50th cycle discharge capacity (C 50 ) percentage (C 50 / C 1 × 100) was taken as the capacity retention rate, which is shown in Table 2 below. In addition, in the first discharge cycle, the voltage drop (△V) for 60 seconds was divided by the current to obtain DCIR (R 1 ) for the 50th discharge cycle, the DCIR (R 50 ) percentage (R 50 / R1 × 100) was taken as the resistance increase rate, which is shown in Table 2 below.

[0138] [Table 2]

[0139] Referring to Table 1 and FIG. 5, the positive electrode active material prepared using the positive electrode active material precursor according to the present invention has an average particle size (D 50 ) and a high degree of monoparticle formation. This shows that the positive electrode active material precursor according to the present invention can be effectively used when producing medium to large monoparticles. Furthermore, referring to Table 2, it can be seen that the positive electrode active materials of Examples 1 to 3 were produced by firing the precursor at a relatively low temperature compared to the positive electrode active materials of Comparative Examples 1 and 2, but monoparticles were well formed and the battery performance was comparable or superior.

[0140] In conclusion, the cathode active material precursor according to the present invention uses a mixture of a first cathode active material precursor containing a composite transition metal in a single particle form and a second cathode active material precursor and / or a third cathode active material precursor, so that a cathode active material in a single particle form can be obtained even if the cathode active material precursor is fired at a temperature relatively lower than the temperature required to form a single particle in the past during the preparation of the cathode active material. Furthermore, it can be seen that the cathode active material prepared by the method for preparing a cathode 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 a composition represented by the following chemical formula 1 and including a composite transition metal in a single particle form; and at least one selected from a second positive electrode active material precursor having a composition represented by Chemical Formula 2 below, and a third positive electrode active material precursor having a composition represented by Chemical Formula 3 below: [Chemical formula 1] Ni ａ１ M １ ｂ１ Mn ｃ１ M ２ ｄ１ In the above 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, and 0≦d1≦0.2, [Chemical formula 2] M ３ ａ２ M ４ ｂ２ (OH) ｃ２ In the above 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 above 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 2. The positive electrode active material precursor according to claim 1, wherein the average particle diameter is 0.1 μm to 15 μm.

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

4. The cathode active material precursor of claim 1 , wherein the second cathode 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 2. The positive electrode active material precursor according to claim 1, wherein the average particle diameter is 0.01 μm to 10 μm.

6. The cathode active material precursor of 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 2. The positive electrode active material precursor according to claim 1, wherein the average particle diameter is 0.01 μm to 10 μm.

8. 2. The positive electrode active material precursor of claim 1, wherein the positive electrode active material precursor comprises at least one 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 based on 100 parts by weight of the first positive electrode active material precursor.

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

10. Produced by the production method according to claim 9, Average particle size (D ５０ ) is 3 μm to 12 μm.

11. Average particle size (D ５０ 11. The positive electrode active material in a single particle form according to claim 10, wherein the particle diameter is 4 μm to 8 μm.

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