Method for producing positive electrode active material and positive electrode active material

Abstract

The present invention relates to a method for producing a positive electrode active material and a positive electrode active material, and includes: (A) a step of producing a composite transition metal hydroxide containing zirconium by performing a coprecipitation reaction while introducing a transition metal-containing solution containing at least one selected from nickel, cobalt, and manganese, a zirconium-containing raw material substance, an ammonium cation complexing agent, and a basic solution into a reactor; and (B) a step of producing a lithium composite transition metal oxide by mixing the composite transition metal hydroxide containing zirconium with a lithium-containing raw material substance and an aluminum-containing raw material substance and firing them. The lithium composite transition metal oxide is an invention relating to a method for producing a positive electrode active material containing at least one selected from nickel, cobalt, and manganese, zirconium, and aluminum, and a positive electrode active material produced by such a production method.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0069033, filed on June 7, 2022, and all of the contents disclosed in the document of the Korean Patent Application are incorporated herein by reference as part of this specification.

[0002] The present invention relates to a method for manufacturing a positive electrode active material and a positive electrode active material.

Background Art

[0003] Recently, with the rapid market expansion of the electric vehicle market, the development of lithium-ion batteries has been accelerating globally. Along with this, high performance such as the driving range and output of electric vehicles is required. Therefore, research has been conducted in the direction of increasing the nickel content of NCM-based lithium composite transition metal oxides, which are the main materials of the positive electrode active material contained in lithium-ion batteries. However, as the nickel content increases, Ni 2+ to Ni 3+ or Ni 4+ oxidation occurs, rapid oxygen desorption takes place, and the desorbed oxygen and Ni 4+ cause side reactions with the electrolyte, resulting in problems such as a decrease in the performance of the battery's life and resistance.

[0004] To solve this problem, there is a method of mixing a positive electrode active material precursor and a lithium-containing raw material substance and performing doping or coating by mixing a doping raw material substance or a coating raw material substance during firing. However, it is difficult to control the doping element and the coating element to be uniformly distributed, and due to non-uniform reactions, various performances in the battery decrease, and there is a situation that needs improvement.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention is for solving the above problems, and specifically provides a method for manufacturing a cathode active material with less zirconium present in an aggregated state on the surface, and with the content of each of aluminum and zirconium present inside being higher than the content of each of aluminum and zirconium present on the surface.

Means for Solving the Problems

[0006] In order to solve the above problems, the present invention provides a method for manufacturing a cathode active material, a cathode active material, a cathode, and a lithium secondary battery.

[0007] (1) The present invention includes: (A) a step of producing a composite transition metal hydroxide containing zirconium by subjecting a transition metal-containing solution containing at least one selected from nickel, cobalt, and manganese, a zirconium-containing raw material substance, an ammonium cation complexing agent, and a basic solution to a coprecipitation reaction while introducing them into a reactor; and (B) a step of producing a lithium composite transition metal oxide by mixing the composite transition metal hydroxide containing zirconium with a lithium-containing raw material substance and an aluminum-containing raw material substance and firing them. The lithium composite transition metal oxide provides a method for manufacturing a cathode active material containing at least one selected from nickel, cobalt, and manganese, zirconium, and aluminum.

[0008] (2) In the present invention according to (1) above, the zirconium-containing raw material substance is at least one selected from zirconium hydroxide, zirconium sulfate, zirconium acetate, zirconium nitrate, zirconium halide, zirconium sulfide, and zirconium oxyhydroxide, and provides a method for manufacturing a cathode active material.

[0009] (3) In the present invention according to (1) or (2) above, the zirconium-containing raw material substance is introduced such that the zirconium content is 1000 ppm to 9000 ppm with respect to the total weight of the composite transition metal hydroxide containing zirconium, and provides a method for manufacturing a cathode active material.

[0010] (4) The present invention provides a method for manufacturing a positive electrode active material, wherein in any one of (1) to (3) above, the aluminum-containing raw material substance is one or more selected from aluminum hydroxide, aluminum oxide, aluminum sulfate, aluminum acetate, aluminum nitrate, aluminum halide, aluminum sulfide, and aluminum oxyhydroxide.

[0011] (5) The present invention provides a method for manufacturing a positive electrode active material, wherein in any one of (1) to (4) above, the aluminum-containing raw material substance is introduced so that the aluminum content is 1000 ppm to 9000 ppm with respect to the total weight of the lithium composite transition metal oxide.

[0012] (6) The present invention provides a method for manufacturing a positive electrode active material, wherein in any one of (1) to (5) above, the firing in the step (B) is performed at a temperature of 700 °C to 800 °C.

[0013] (7) The present invention provides a positive electrode active material including a lithium composite transition metal oxide containing at least one selected from nickel, cobalt, and manganese, and zirconium and aluminum, wherein the weight ratio of aluminum present inside to aluminum present on the surface is more than 1.0, and the weight ratio of zirconium present inside to zirconium present on the surface is more than 1.0.

[0014] (8) The present invention provides a positive electrode active material, wherein in (7) above, the lithium composite transition metal oxide contains zirconium in an amount of 1000 ppm to 9000 ppm with respect to the total weight.

[0015] (9) The present invention provides a positive electrode active material, wherein in (7) or (8) above, the lithium composite transition metal oxide contains aluminum in an amount of 1000 ppm to 9000 ppm with respect to the total weight.

[0016] (10) The present invention provides a positive electrode active material, wherein in any one of (7) to (9) above, the average particle size (D 50To provide a positive electrode active material having a particle size of 3 μm to 20 μm.

[0017] (11) The present invention provides a positive electrode containing the positive electrode active material according to any one of (7) to (10).

[0018] (12) The present invention provides a lithium secondary battery including the positive electrode of (11).

Advantages of the Invention

[0019] According to the method for producing the positive electrode active material of the present invention, it is possible to provide a positive electrode active material in which zirconium present in an aggregated state on the surface is less, and the content of each of aluminum and zirconium present inside is higher than the content of each of aluminum and zirconium present on the surface.

[0020] In addition, the positive electrode active material according to the present invention can improve the performance of the battery when applied to the battery.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0022] The terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. The inventors should interpret them in accordance with the meaning and concept that conform to the technical idea of the present invention, in accordance with the principle that they can appropriately define the concept of the terms in order to explain their invention in the best way.

[0023] In this specification, terms such as "comprising", "including" or "having" are intended to specify that there are implemented features, numbers, steps, components or combinations thereof, and should be understood not to preclude the presence or addition possibility of one or more different features, numbers, steps, components or combinations thereof in advance.

[0024] In this specification, the term "on" means not only when a certain component is formed directly on the upper surface of another component, but also when a third component is interposed between these components.

[0025] In this specification, the term "average particle size (D 50 )" means the particle size at the 50% point of the volume cumulative distribution by particle size. After dispersing the powder to be measured in a dispersion medium, the average particle size is introduced into a commercially available laser diffraction particle size analyzer (for example, S3500 manufactured by Microtrac), and when the particles pass through the laser beam, the difference in the diffraction pattern due to the particle size is measured to calculate the particle size distribution, and the particle diameter at the point where the volume cumulative distribution by particle size in the measuring device reaches 50% is calculated to measure D 50 .

[0026] Hereinafter, the present invention will be described in detail.

[0027] Method for manufacturing a positive electrode active material The inventors of the present invention have found that when manufacturing a composite transition metal hydroxide, if zirconium is doped first, not only the distribution of zirconium but also the distribution of aluminum introduced during firing can be adjusted in the finally manufactured positive electrode active material, and when the positive electrode active material is applied to a battery, the performance of the battery is improved, and thus the present invention has been completed.

[0028] Conventionally, when attempting to dope a doping element into a positive electrode active material, a method was used in which a composite transition metal hydroxide precursor and a lithium-containing raw material substance were mixed and fired together with a doping element raw material substance. However, in the present invention, by doping zirconium into the composite transition metal hydroxide precursor first, that is, by doping zirconium first during the production of the composite transition metal hydroxide, not only the distribution of zirconium but also the distribution of aluminum introduced in the step of mixing and firing the precursor and the lithium-containing raw material substance can be adjusted.

[0029] The present invention provides a method for producing a positive electrode active material comprising: (A) a step of producing a composite transition metal hydroxide containing zirconium by subjecting a transition metal-containing solution containing at least one selected from nickel, cobalt, and manganese, a zirconium-containing raw material substance, an ammonium cation complexing agent, and a basic solution to a coprecipitation reaction while introducing them into a reactor; and (B) a step of mixing and firing the composite transition metal hydroxide containing zirconium with a lithium-containing raw material substance and an aluminum-containing raw material substance to produce a lithium composite transition metal oxide, wherein the lithium composite transition metal oxide contains at least one selected from nickel, cobalt, and manganese, zirconium, and aluminum.

[0030] The method for producing a positive electrode active material according to the present invention may further include (C) a step of mixing a coating element-containing raw material substance with the lithium composite transition metal oxide and performing a heat treatment to form a coating layer.

[0031] Hereinafter, each step of the method for producing a positive electrode active material will be described in more detail.

[0032] (Step (A)) The method for producing a positive electrode active material according to the present invention includes a step of producing a composite transition metal hydroxide containing zirconium by performing a coprecipitation reaction while introducing a transition metal-containing solution containing at least one selected from nickel, cobalt, and manganese, a zirconium-containing raw material substance, an ammonium cation complex-forming agent, and a basic solution into a reactor.

[0033] The step (A) is a step of generating and growing nuclei of composite transition metal hydroxide particles, which are positive electrode active material precursors, by a precipitation reaction while introducing the transition metal-containing solution, the zirconium-containing raw material substance, the ammonium cation complex-forming agent, and the basic solution into the reactor.

[0034] The transition metal-containing solution can contain 60 mol% or more of nickel (Ni) among all the metals. The transition metal-containing solution can contain 60 mol% or more, 70 mol% or more, 80 mol% or more, or 85 mol% or more of nickel (Ni) among all the metals for improving capacity.

[0035] The transition metal-containing solution can contain at least one selected from a nickel raw material substance, a cobalt raw material substance, and a manganese raw material substance.

[0036] The nickel raw material substance can be nickel-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, etc. Specifically, Ni(OH) 2 , NiO, NiOOH, NiCO 3 ·2Ni(OH) 2 ·4H 2 O, NiC 2 O 2 ·2H 2 O, Ni(NO 3 ) 2 ·6H 2 O, NiSO 4 , NiSO 4 ·6H 2 O, Ni(SO 3 ) 2 or a combination thereof, but is not limited thereto.

[0037] The cobalt raw material substance can be cobalt-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, etc. Specifically, Co(OH) 2 , CoOOH, Co(OCOCH 3 ) 2 ·4H 2 O, Co(NO 3 ) 2 ·6H 2 O, CoSO 4 , Co(SO 4 ) 2 ·7H 2 O, Co(SO 3 ) 2 or a combination thereof, but is not limited thereto.

[0038] The manganese-containing raw material substance can be manganese-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide or oxyhydroxide, etc. Specifically, Mn 2 O 3 , MnO 2 , Mn 3 O 4 , MnCO 3 , Mn(NO 3 ) 2 , MnSO 4 , Mn(SO 3 ) 2 , manganese acetate, manganese dicarboxylate, manganese citrate, manganese fatty acid salt, manganese oxyhydroxide, manganese chloride or a combination thereof, but is not limited thereto.

[0039] The transition metal-containing solution can be produced by adding one or more selected from nickel-containing raw material substances, cobalt-containing raw material substances and manganese-containing raw material substances to a solvent, specifically water, or a mixed solvent of water and an organic solvent (for example, alcohol, etc.) that can be uniformly mixed therewith, but is not limited thereto.

[0040] According to the present invention, the zirconium-containing raw material substance can be one or more selected from zirconium hydroxide, zirconium sulfate, zirconium acetate, zirconium nitrate, zirconium halide, zirconium sulfide, and zirconium oxyhydroxide. Specifically, the zirconium-containing raw material substance can be zirconium hydroxide, zirconium sulfate, or a combination thereof, and more specifically, it can be zirconium sulfate. In this case, it can be coprecipitated with the transition metal contained in the transition metal-containing solution under the same conditions as the transition metal contained in the transition metal-containing solution.

[0041] According to the present invention, the zirconium-containing raw material substance can be introduced such that the zirconium content is 1000 ppm to 9000 ppm, specifically 1000 ppm, 1500 ppm, 2000 ppm or more, 7000 ppm, 8000 ppm, 9000 ppm or less, based on the total weight of the composite transition metal hydroxide containing zirconium. In this case, the structural stability of the finally produced positive electrode active material can be increased, and the life characteristics can be further improved.

[0042] On the other hand, the zirconium-containing raw material substance can be introduced into a transition metal-containing solution containing one or more selected from nickel, cobalt, and manganese. That is, the transition metal-containing solution can contain one or more selected from nickel, cobalt, and manganese and zirconium.

[0043] The ammonium cation complexing agent is, for example, NH 4 OH, (NH 4 ) 2 SO 4 、NH 4 NO 3 、NH 4 Cl、CH 3 COONH 4 、NH 4 CO 3Or it can be these combinations, but is not limited thereto. On the other hand, the ammonium cation complexing agent may be used in the form of an aqueous solution. Here, as the solvent, water, or a mixture of water and an organic solvent (e.g., alcohol) that can be uniformly mixed with water can be used.

[0044] The basic solution can contain hydroxides of alkali metals or alkaline earth metals such as NaOH, KOH, or Ca(OH) 2 etc., hydrates thereof, or alkali compounds of these combinations. The basic solution may also be used in the form of an aqueous solution. Here, as the solvent, water, or a mixture of water and an organic solvent (e.g., alcohol) that can be uniformly mixed with water can be used.

[0045] The transition metal-containing solution, zirconium-containing raw material substance, ammonium cation complexing agent, and basic solution can be continuously introduced into the reactor.

[0046] The coprecipitation reaction can be carried out under an inert atmosphere. For example, the coprecipitation reaction can be carried out after purging nitrogen gas into the reactor to remove dissolved oxygen.

[0047] The coprecipitation reaction can be carried out at pH 12.0 - 13.0, specifically 12.0 - 12.5, and more specifically 12.0 - 12.2 in order to reduce and make uniform the particle size of the composite transition metal hydroxide.

[0048] The coprecipitation reaction can be carried out at a temperature of 40°C - 60°C, specifically 45°C - 55°C, and more specifically 48°C - 52°C. When the coprecipitation reaction is carried out at a temperature within the above range, the energy required for the coprecipitation reaction can be provided, and a smooth coprecipitation reaction can be carried out.

[0049] The coprecipitation reaction can be carried out between 25 hours, 35 hours, 45 hours or more, 60 hours, 70 hours, and 80 hours or less. In this case, uniform particles can be generated.

[0050] As a result, the composite transition metal hydroxide produced by the step (A) can have a composition represented by the following Chemical Formula 1.

[0051] [Chemical Formula 1] Ni a1 Co b1 Mn c1 Zr d1 M 1 e1 (OH) 2

[0052] In Chemical Formula 1, M 1 , is one or more selected from B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, Ce, Hf, F, P, S, and La, 0.60 ≦ a1 < 1.0, 0 < b1 ≦ 0.40, 0 < c1 ≦ 0.40, 0 < d1 ≦ 0.10, 0 ≦ e1 ≦ 0.10, and a1 + b1 + c1 + d1 + e1 = 1.

[0053] The a1 means the atomic fraction of nickel among the metal elements in the composite transition metal hydroxide, and can be 0.60, 0.70, 0.80, 0.85 or more, 0.95, 0.98 or less.

[0054] The b1 means the atomic fraction of cobalt among the metal elements in the composite transition metal hydroxide, and can be 0.01, 0.02, 0.03 or more, 0.10, 0.30, 0.40 or less.

[0055] The c1 means the atomic fraction of manganese among the metal elements in the composite transition metal hydroxide, and can be 0.01, 0.02, 0.03 or more, 0.10, 0.30, 0.40 or less.

[0056] Said d1 represents the elemental fraction of zirconium among the metal elements in the composite transition metal hydroxide, and can be greater than 0, 0.01 or more, 0.02, 0.05, and 0.10 or less.

[0057] Said e1 represents the elemental fraction of element M among the metal elements in the composite transition metal hydroxide, and can be 0, 0.01 or more, 0.02, 0.05, and 0.10 or less. 1

[0058] On the other hand, when the transition metal-containing solution further contains ions of element M, 1 a transition metal-containing solution can be produced by adding an element M-containing raw material substance to the solvent together. 1

[0059] (B) Step The method for producing a positive electrode active material according to the present invention includes (B) a step of mixing a composite transition metal hydroxide containing zirconium with a lithium-containing raw material substance and an aluminum-containing raw material substance, and firing to produce a lithium composite transition metal oxide. Here, the lithium composite transition metal oxide contains one or more selected from nickel, cobalt, and manganese, zirconium, and aluminum.

[0060] According to the present invention, the distribution of aluminum in the lithium composite transition metal oxide produced by firing in the (B) step can be adjusted when the composite transition metal hydroxide contains zirconium, and the lithium composite transition metal oxide produced has a weight ratio of aluminum present inside to aluminum present on the surface greater than 1.0, and a weight ratio of zirconium present inside to zirconium present on the surface can be greater than 1.0. Thereby, the initial resistance (initial DCIR) characteristics, life characteristics, and thermal stability of a battery including the positive electrode active material produced according to the present invention can all be improved. On the other hand, the surface can be a region within 1 μm from the outermost side of the lithium composite transition metal oxide.

[0061] ​​The lithium-containing raw material substance can be a lithium-containing carbonate (e.g., lithium carbonate, etc.), a hydrate (e.g., lithium hydroxide hydrate (LiOH·H 2 O), etc.), a hydroxide (e.g., lithium hydroxide, etc.), a nitrate (e.g., lithium nitrate (LiNO 3 ), etc.), a chloride (e.g., lithium chloride (LiCl), etc.), and the like.

[0062] The aluminum-containing raw material substance is introduced for improving the initial resistance characteristics, life characteristics, and thermal stability of the battery, and the aluminum-containing raw material substance can be a zirconium-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, etc.

[0063] According to the present invention, the aluminum-containing raw material substance can be one or more selected from aluminum hydroxide, aluminum oxide, aluminum sulfate, aluminum acetate, aluminum nitrate, aluminum halide, aluminum sulfide, and aluminum oxyhydroxide. Specifically, the aluminum-containing raw material substance can be aluminum hydroxide, aluminum oxide, or a combination thereof, and more specifically, it can be aluminum hydroxide.

[0064] According to the present invention, the aluminum-containing raw material substance can be introduced such that aluminum is 1000 ppm to 9000 ppm, specifically 1000 ppm, 1500 ppm, 2000 ppm or more, 7000 ppm, 8000 ppm, 9000 ppm or less, based on the total weight of the lithium composite transition metal oxide. In this case, the side reaction between the resulting positive electrode active material and the electrolytic solution can be reduced, and the deterioration of the positive electrode active material can be suppressed.

[0065] On the one hand, the mixing of the composite transition metal hydroxide containing zirconium, the lithium-containing raw material substance, and the aluminum-containing raw material substance can be carried out by solid-phase mixing. Further, the mixing ratio of the composite transition metal hydroxide and the lithium-containing raw material substance can be determined within a range that satisfies the atomic fraction of each component in the finally produced positive electrode active material. For example, the composite transition metal hydroxide and the lithium-containing raw material substance can be mixed in an amount such that the molar ratio of transition metal:Li is 1:0.9 to 1:1.2, specifically 1:0.95 to 1:1.1. When the composite transition metal hydroxide and the lithium-containing raw material substance are mixed within the above range, a positive electrode active material exhibiting excellent capacity characteristics can be produced.

[0066] According to the present invention, the firing in the step (B) can be carried out at a temperature of 680°C to 900°C, specifically 680°C, 690°C, 700°C or higher, 870°C, 880°C, 890°C, 900°C or lower. In this case, a positive electrode active material exhibiting excellent capacity characteristics can be produced.

[0067] The firing can be carried out in an oxygen atmosphere for a stable reaction between the transition metal, particularly nickel and lithium, and the formation of a stable structure.

[0068] The firing can be carried out for 15 hours, 17 hours, 20 hours or more, 30 hours, 33 hours, 35 hours or less. In this case, a layered structure can be stably formed, and a positive electrode active material exhibiting excellent capacity characteristics can be produced.

[0069] As a result, the lithium composite transition metal oxide produced in the step (B) can have a composition represented by the following Chemical Formula 2.

[0070] [Chemical Formula 2] Li 1+x Ni a2 Co b2 Mn c2 Zr d2 Al e2 M 2 f2 O2

[0071] In the formula (2), M 2 is one or more selected from B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, Ce, Hf, F, P, S, and La, 0.60 ≦ a2 < 1.0, 0 < b2 ≦ 0.40, 0 < c2 ≦ 0.40, 0 < d2 ≦ 0.10, 0 < e2 ≦ 0.10, 0 ≦ f2 ≦ 0.10, and a2 + b2 + c2 + d2 + e2 + f2 = 1.

[0072] The a2 represents the atomic fraction of nickel among the metal elements in the lithium composite transition metal oxide, and can be 0.60, 0.70, 0.80, 0.85 or more, 0.95, 0.98 or less.

[0073] The b2 represents the atomic fraction of cobalt among the metal elements in the lithium composite transition metal oxide, and can be 0.01, 0.02, 0.03 or more, 0.10, 0.30, 0.40 or less.

[0074] The c2 represents the atomic fraction of manganese among the metal elements in the lithium composite transition metal oxide, and can be 0.01, 0.02, 0.03 or more, 0.10, 0.30, 0.40 or less.

[0075] The d2 represents the elemental fraction of zirconium among the metal elements in the lithium composite transition metal oxide, and can be more than 0, 0.01 or more, 0.02, 0.05, 0.10 or less.

[0076] The e2 represents the elemental fraction of aluminum among the metal elements in the lithium composite transition metal oxide, and can be more than 0, 0.01 or more, 0.02, 0.05, 0.10 or less.

[0077] The f2 represents the elemental fraction of the M 2 element among the metal elements in the lithium composite transition metal oxide, and can be 0, 0.01 or more, 0.02, 0.05, 0.10 or less.

[0078] (C) Step The method for manufacturing a positive electrode active material according to the present invention may further include a step (C) of mixing a coating element-containing raw material substance with the lithium composite transition metal oxide and performing heat treatment to form a coating layer.

[0079] The metal elements contained in the coating element-containing raw material substance can be, for example, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and Y. The coating element-containing raw material substance can be an acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide containing the metal element. For example, when the metal element is B, boric acid (H 3 BO 3 ) etc. can be used.

[0080] The coating element-containing raw material substance can be contained in an amount of 200 ppm to 2000 ppm by weight based on the lithium transition metal oxide. When the content of the coating element-containing raw material substance is within the above range, the capacity of the battery can be improved, the formed coating layer can suppress the direct reaction between the electrolyte and the lithium transition metal oxide, and the long-term performance characteristics of the battery can be improved.

[0081] The heat treatment in the step (C) can be performed at a temperature of 200°C to 400°C. When the heat treatment temperature is within the above range, a coating layer can be formed while maintaining the structural stability of the transition metal oxide. The heat treatment in the step (C) can be performed for 1 hour to 10 hours. When the heat treatment time is within the above range, an appropriate coating layer can be formed and the production efficiency can be improved.

[0082] Positive electrode active material The present invention includes a lithium composite transition metal oxide containing one or more selected from nickel, cobalt, and manganese, and containing zirconium and aluminum, The weight ratio of aluminum present inside to aluminum present on the surface is greater than 1.0, and a positive electrode active material is provided in which the weight ratio of zirconium present inside to zirconium present on the surface is greater than 1.0.

[0083] The positive electrode active material according to the present invention can be manufactured by the method for manufacturing the positive electrode active material described above. Further, the lithium composite transition metal oxide can have the composition represented by Chemical Formula 2. On the other hand, the surface can be a region within 1 μm from the outermost side of the lithium composite transition metal oxide.

[0084] Since the lithium composite transition metal oxide contains all of zirconium and aluminum, not only is the structural stability improved, but it can also serve as an HF scavenger, and all of the battery life characteristics, resistance characteristics, and thermal stability can be improved. On the other hand, when the lithium composite transition metal oxide does not contain zirconium, there is a problem that the structural stability decreases and the life and storage characteristics deteriorate. When it does not contain aluminum, there are problems such as an increase in battery resistance due to deterioration such as an increase in side reactions, a decrease in life characteristics, and a decrease in thermal stability.

[0085] When the weight ratio of aluminum present inside to aluminum present on the surface is greater than 1.0, the side reaction with the electrolytic solution decreases and the cycle characteristics are improved. On the other hand, when it is 1.0 or less, the deterioration of the positive electrode active material is accelerated by the side reaction with the electrolytic solution, and as a result, there is a problem that the cycle characteristics deteriorate.

[0086] When the weight ratio of zirconium present inside to zirconium present on the surface is greater than 1.0, it helps to stabilize the lattice and the cycle characteristics are improved. On the other hand, when it is 1.0 or less, the amount of zirconium oxide present on the surface increases and there is a problem of increased resistance.

[0087] According to the present invention, the lithium composite transition metal oxide can contain zirconium in an amount of 1000 ppm to 9000 ppm, specifically, 1000 ppm, 1500 ppm, 2000 ppm or more, 7000 ppm, 8000 ppm, 9000 ppm or less. In this case, the life characteristics can be improved due to the increased structural stability.

[0088] According to the present invention, the lithium composite transition metal oxide can contain aluminum in an amount of 1000 ppm to 9000 ppm, specifically, 1000 ppm, 1500 ppm, 2000 ppm or more, 7000 ppm, 8000 ppm, 9000 ppm or less. In this case, the side reaction with the electrolyte can be reduced, and the deterioration of the positive electrode active material can be suppressed.

[0089] According to the present invention, the lithium composite transition metal oxide can have a composition represented by the following Chemical Formula 2.

[0090] [Chemical Formula 2] Li 1+x Ni a2 Co b2 Mn c2 Zr d2 Al e2 M 2 f2 O 2

[0091] In the Chemical Formula 2, M 2 is one or more selected from B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, Ce, Hf, F, P, S, and La, 0.60 ≦ a2 < 1.0, 0 < b2 ≦ 0.40, 0 < c2 ≦ 0.40, 0 < d2 ≦ 0.10, 0 < e2 ≦ 0.10, 0 ≦ f2 ≦ 0.10, and a2 + b2 + c2 + d2 + e2 + f2 = 1.

[0092] The a2 represents the atomic fraction of nickel among the metal elements in the lithium composite transition metal oxide, and can be 0.60, 0.70, 0.80, 0.85 or more, 0.95, 0.98 or less.

[0093] The above-mentioned b2 represents the atomic fraction of cobalt among the metal elements in the lithium composite transition metal oxide, and it can be 0.01, 0.02, 0.03 or more, and 0.10, 0.30, 0.40 or less.

[0094] The above-mentioned c2 represents the atomic fraction of manganese among the metal elements in the lithium composite transition metal oxide, and it can be 0.01, 0.02, 0.03 or more, and 0.10, 0.30, 0.40 or less.

[0095] The above-mentioned d2 represents the elemental fraction of zirconium among the metal elements in the lithium composite transition metal oxide, and it can be more than 0, 0.01 or more, and 0.02, 0.05, 0.10 or less.

[0096] The above-mentioned e2 represents the elemental fraction of aluminum among the metal elements in the lithium composite transition metal oxide, and it can be more than 0, 0.01 or more, and 0.02, 0.05, 0.10 or less.

[0097] The above-mentioned f2 represents the elemental fraction of element M among the metal elements in the lithium composite transition metal oxide, and it can be 0, 0.01 or more, and 0.02, 0.05, 0.10 or less. 2 The above-mentioned f2 represents the elemental fraction of element M among the metal elements in the lithium composite transition metal oxide, and it can be 0, 0.01 or more, and 0.02, 0.05, 0.10 or less.

[0098] According to the present invention, the above-mentioned positive electrode active material has an average particle size (D 50 ) of 3 μm to 20 μm. Specifically, it can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or more, and 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or less. In this case, the performance of the battery can be further improved.

[0099] Positive electrode In addition, the present invention can provide a positive electrode for a lithium secondary battery including the above-mentioned positive electrode active material.

[0100] 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 and including the above-mentioned positive electrode active material.

[0101] 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. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or those obtained by surface treatment of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. can be used. Further, the positive electrode current collector can usually have a thickness of 3 μm to 500 μm, and fine irregularities can also be formed on the surface of the current collector to enhance the adhesive force of the positive electrode active material. For example, it can be used in various forms such as films, sheets, foils, meshes, porous bodies, foams, non-woven bodies, etc.

[0102] The positive electrode active material layer can contain a conductive material and a binder together with the positive electrode active material.

[0103] Here, the positive electrode active material can be contained in a content of 80% by weight to 99% by weight, more specifically 85% by weight to 98% by weight, based on the total weight of the positive electrode active material layer. When contained within the above content range, excellent capacity characteristics can be exhibited.

[0104] Here, the conductive material is used to impart conductivity to the electrode, and in the configured battery, it can be used without particular limitation as long as it does not cause a chemical change and has electron conductivity. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based substances such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. Among these, one kind alone or a mixture of two or more kinds can be used. The conductive material can 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.

[0105] The binder serves to improve the adhesion between the positive electrode active material particles and the adhesive force 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. Among these, one kind alone or a mixture of two or more kinds can be used. The binder can be contained in an amount of 1% to 30% by weight based on the total weight of the positive electrode active material layer.

[0106] Except for using the above-described positive electrode active material, the positive electrode can be manufactured by a normal method for manufacturing a positive electrode. Specifically, it can be manufactured by applying a positive electrode composite material, which is prepared by dissolving or dispersing the above-described positive electrode active material, and optionally a binder and a conductive material in a solvent, onto a positive electrode current collector, and then drying and rolling. Here, the types and contents of the positive electrode active material, binder, and conductive material are as described above. As another method, the positive electrode can also be manufactured by casting the positive electrode composite material onto another support, and then laminating the film obtained by peeling off from this support onto the positive electrode current collector.

[0107] As the solvent, it can be a solvent commonly used in the technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone or water, etc. Among these, one kind alone or a mixture of two or more kinds can be used. The usage amount of the solvent is considered in view of the coating thickness of the slurry and the production yield, and is sufficient as long as it can dissolve or disperse the positive electrode active material, the conductive material and the binder, and then has a viscosity capable of showing excellent thickness uniformity during coating for the production of the positive electrode.

[0108] Lithium secondary battery In addition, the present invention can manufacture an electrochemical element including the positive electrode. Specifically, the electrochemical element can be a battery, a capacitor, etc., and more specifically, it can be a lithium secondary battery.

[0109] The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite to the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. Since the positive electrode is as described above, specific description is omitted, and hereinafter, only the remaining configurations will be specifically described.

[0110] In addition, the lithium secondary battery can selectively further include a battery container for housing the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member for sealing the battery container.

[0111] In the lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0112] 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. For example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, those obtained by surface treatment with carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. can be used. Further, the negative electrode current collector can usually have a thickness of 3 μm to 500 μm, and similar to the positive electrode current collector, fine irregularities can be formed on the surface of the current collector to strengthen the binding force of the negative electrode active material. For example, it can be used in various forms such as films, sheets, foils, meshes, porous bodies, foams, non-woven fabric bodies, etc.

[0113] The negative electrode active material layer selectively contains a binder and a conductive material together with the negative electrode active material.

[0114] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fibers, 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; SiO β (0 < β < 2), SnO 2, metal oxides such as vanadium oxides and lithium vanadium oxides that can be doped and undoped with lithium; or composites containing the metallic compound and a carbonaceous material such as Si-C composites or Sn-C composites, etc. may be mentioned, and mixtures of any one or two or more of these can be used. Further, as the negative electrode active material, a thin film of metallic lithium may be used. Also, as the carbon material, both low-crystalline carbon and high-crystalline carbon can be used. Representative examples of low-crystalline carbon are soft carbon and hard carbon, and representative examples of high-crystalline carbon are amorphous, plate-like, flaky, spherical or fibrous natural graphite 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.

[0115] The negative electrode active material can 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.

[0116] The binder is a component that helps bind the conductive material, active material, and current collector, and can usually be 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, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluorine rubber, and various copolymers thereof.

[0117] The conductive material is a component for further improving the conductivity of the negative electrode active material, and can 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. For example, graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, 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; conductive materials such as polyphenylene derivatives can be used.

[0118] The negative electrode active material layer is produced by applying and drying a negative electrode composite material prepared by dissolving and dispersing a negative electrode active material, and optionally a binder and a conductive material, in a solvent on a negative electrode current collector, or by casting the negative electrode composite material on another support and then laminating a film obtained by peeling the support on the negative electrode current collector.

[0119] On the one hand, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a migration path for lithium ions. Usually, any material that can be used as a separator in a lithium secondary battery can be used without particular limitation. In particular, a material that has a low resistance to the ion migration of the electrolyte and excellent moisture retention ability of the electrolyte solution is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene 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. Also, a normal porous nonwoven fabric, for example, a nonwoven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc. may be used. Further, for ensuring heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer substance may be used, and optionally, it can be used in a single-layer or multilayer structure.

[0120] In addition, examples of the electrolyte 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 during the manufacture of lithium secondary batteries.

[0121] Specifically, the electrolyte can contain an organic solvent and a lithium salt.

[0122] As the organic solvent, any substance can be used without particular limitation as long as it serves as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, examples of the organic solvent 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; carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol 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 contain a double bond, aromatic ring, or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes. 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, which can enhance the charge-discharge performance of the battery, and a linear carbonate compound with low viscosity (e.g., ethylmethylcarbonate, dimethylcarbonate, or diethylcarbonate) is more preferred. In this case, the cyclic carbonate and the linear carbonate can be mixed and used at a volume ratio of about 1:1 to about 1:9, enabling excellent performance of the electrolyte solution to be exhibited.

[0123] The lithium salt can be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, examples of the lithium salt include LiPF 6 、LiClO 4 、LiAsF 6 、LiBF 4 、LiSbF 6 、LiAl0 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 and the like can be used. The concentration of the lithium salt is preferably in the range of 0.1 M to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0124] In addition to the electrolyte constituent components, the electrolyte may further contain one or more additives such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethyl alcoholamine, cyclic ether, ethylenediamine, n-glyme, triamide hexaline, nitrobenzene derivatives, sulfur, quinoneimine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethyl alcohol or aluminum trichloride for the purpose of improving the life characteristics of the battery, suppressing the capacity reduction of the battery, improving the discharge capacity of the battery, etc. Here, the additive can be contained in an amount of 0.1% by weight to 5% by weight based on the total weight of the electrolyte.

[0125] As described above, the lithium secondary battery containing the positive electrode active material according to the present invention exhibits high initial efficiency, low initial resistance, excellent cycle characteristics and thermal stability, and thus is useful in portable devices such as mobile phones, notebook personal computers, digital cameras, etc., and in the field of electric vehicles such as hybrid electric vehicles (HEV).

[0126] Accordingly, according to another embodiment of the present invention, a battery module containing the lithium secondary battery as a unit cell and a battery pack containing the same are provided.

[0127] The battery module or battery pack can be used as a medium to large-sized device power source for any one or more of power tools; electric vehicles including electric vehicles (EV), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEV); or power storage systems.

[0128] The outer shape of the lithium secondary battery of the present invention is not particularly limited, and it can be a cylindrical shape, a rectangular shape, a pouch type, a coin type, etc. using a can.

[0129] The lithium secondary battery according to the present invention can be used for a battery cell used as a power source for a small device, and can also be preferably used as a unit cell for a medium or large battery module including a large number of battery cells.

[0130] Hereinafter, the embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field 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.

[0131] Examples and comparative examples Example 1 NiSO 4 、CoSO 4 、MnSO 4 、Zr(SO 4 ) 2 were mixed in deionized water in an amount such that the molar ratio of nickel:cobalt:manganese:zirconium was 93.6:2:4:0.4 to prepare a transition metal aqueous solution with a concentration of 2.4M. Also, an aqueous NaOH solution with a concentration of 25 wt% and an aqueous NH 4 OH solution with a concentration of 9 wt% were prepared. For reference, the Zr(SO 4 ) 2 was added so that zirconium was 4500 ppm with respect to the total weight of the positive electrode active material precursor to be produced.

[0132] After putting 82.8 L of deionized water into the reactor, nitrogen gas was purged into the reactor at a rate of 20 L / min to remove dissolved oxygen in the water and make the inside of the reactor a non-oxidizing atmosphere. Next, 158 mL of the NaOH aqueous solution and 6812 mL of the NH 4 OH aqueous solution were added, and then stirred at a stirring speed of 250 rpm at 50 °C to adjust the pH inside the reactor to pH 12.0 - 12.2.

[0133] Thereafter, while stirring at a stirring speed of 650 rpm, the transition metal aqueous solution was continuously fed into the reactor at a rate of 23.9 L / hr, the NaOH aqueous solution was fed at a rate of 14.4 L / hr, and the NH 4 OH aqueous solution was fed at a rate of 3.38 L / hr, and a coprecipitation reaction was carried out at 50 °C and pH 11.6 for 48 hours to produce a cathode active material precursor having a composition of Ni 0.936 Co 0.02 Mn 0.04 Zr 0.004 (OH) 2 .

[0134] The cathode active material precursor, LiOH, and Al(OH) 3 were mixed at a molar ratio of 1:1.05:0.015 and calcined at 755 °C in an oxygen atmosphere for 27 hours to produce a cathode active material (average particle diameter (D 50 ): 13 μm). Here, the cathode active material contains 4000 ppm of zirconium and 4000 ppm of aluminum based on the total weight.

[0135] Example 2 NiSO 4 , CoSO 4 , MnSO 4 , Zr(SO 4 ) 2 were mixed in deionized water in an amount such that the molar ratio of nickel:cobalt:manganese:zirconium was 94.6:2:3:0.4 to prepare a transition metal aqueous solution having a concentration of 2.4 M. Also, a 25 wt% NaOH aqueous solution and a 9 wt% NH 4 OH aqueous solution were prepared. For reference, the Zr(SO 4 ) 2 was added so that the zirconium content was 4500 ppm based on the total weight of the cathode active material precursor to be produced.

[0136] After putting 82.8 L of deionized water into the reactor, nitrogen gas was purged into the reactor at a rate of 20 L / min to remove dissolved oxygen in the water and make the inside of the reactor a non-oxidizing atmosphere. Next, 158 mL of the NaOH aqueous solution and the NH 4After adding 6812 mL of an OH aqueous solution, the mixture was stirred at 50 °C and a stirring speed of 250 rpm to adjust the pH in the reactor to pH 12.0 - 12.2.

[0137] Thereafter, while stirring at a stirring speed of 650 rpm, the transition metal aqueous solution was continuously fed into the reactor at a rate of 23.9 L / hr, the NaOH aqueous solution at a rate of 14.4 L / hr, and the NH 4 OH aqueous solution at a rate of 3.38 L / hr for a coprecipitation reaction at 50 °C and below pH 11.6 for 48 hours to produce a precursor of the cathode active material having a composition of Ni 0.946 Co 0.02 Mn 0.03 Zr 0.004 (OH) 2 and producing a precursor of the cathode active material.

[0138] The precursor of the cathode active material, LiOH, and Al(OH) 3 were mixed at a molar ratio of 1:1.05:0.015 and calcined at 735 °C in an oxygen atmosphere for 27 hours to produce a cathode active material (average particle diameter (D 50 ): 15 μm). Here, the cathode active material contains 4000 ppm of zirconium and 4000 ppm of aluminum with respect to the total weight.

[0139] Example 3 In the same manner as in Example 1, a precursor of the cathode active material having a composition of Ni 0.936 Co 0.02 Mn 0.04 Zr 0.004 (OH) 2 was produced.

[0140] The precursor of the cathode active material, LiOH, and Al(OH) 3 were mixed at a molar ratio of 1:1.05:0.010 and calcined at 755 °C in an oxygen atmosphere for 27 hours to produce a cathode active material (average particle diameter (D 50 ): 13 μm). Here, the cathode active material contains 4000 ppm of zirconium and 2500 ppm of aluminum with respect to the total weight.

[0141] Comparative Example 1 NiSO 4 and CoSO 4, MnSO 4 was mixed in deionized water in an amount such that the molar ratio of nickel:cobalt:manganese was 94:2:4, and an aqueous transition metal solution with a concentration of 2.4 M was prepared. Also, an aqueous NaOH solution with a concentration of 25 wt% and an aqueous NH 4 OH solution with a concentration of 9 wt% were prepared.

[0142] After putting 82.8 L of deionized water into the reactor, nitrogen gas was purged into the reactor at a rate of 20 L / min to remove dissolved oxygen in the water and make the inside of the reactor a non-oxidizing atmosphere. Next, 158 mL of the NaOH aqueous solution and 6812 mL of the NH 4 OH aqueous solution were added, and then stirred at a stirring speed of 250 rpm at 50 °C to adjust the pH inside the reactor to pH 12.0 - 12.2.

[0143] Then, while stirring at a stirring speed of 650 rpm, the transition metal aqueous solution was continuously fed into the reactor at a rate of 23.9 L / hr, the NaOH aqueous solution at a rate of 14.4 L / hr, and the NH 4 OH aqueous solution at a rate of 3.38 L / hr, and a coprecipitation reaction was carried out at 50 °C and below pH 11.6 for 48 hours to produce a precursor of the cathode active material having the composition Ni 0.94 Co 0.02 Mn 0.04 (OH) 2 .

[0144] The precursor of the cathode active material, LiOH, Al(OH) 3 , ZrO 2 were mixed at a molar ratio of 1:1.05:0.015:0.004 and calcined at 755 °C in an oxygen atmosphere for 27 hours to produce a cathode active material (average particle size (D 50 ): 13 μm). Here, the cathode active material contains 4000 ppm of zirconium and 4000 ppm of aluminum with respect to the total weight.

[0145] Comparative Example 2 NiSO 4 , CoSO 4 , MnSO 4Mix in deionized water in an amount such that the molar ratio of nickel:cobalt:manganese is 95:2:3 to prepare an aqueous transition metal solution with a concentration of 2.4 M. Also, prepare an aqueous NaOH solution with a concentration of 25 wt% and an aqueous NH 4 OH solution with a concentration of 9 wt%.

[0146] After putting 82.8 L of deionized water into the reactor, purge nitrogen gas into the reactor at a rate of 20 L / min to remove dissolved oxygen in the water and make the inside of the reactor a non-oxidizing atmosphere. Next, after adding 158 mL of the NaOH aqueous solution and 6812 mL of the NH 4 OH aqueous solution, stir at a stirring speed of 250 rpm at 50 °C to adjust the pH inside the reactor to pH 12.0 - 12.2.

[0147] Then, while stirring at a stirring speed of 650 rpm, continuously introduce the transition metal aqueous solution into the reactor at a rate of 23.9 L / hr, the NaOH aqueous solution at a rate of 14.4 L / hr, and the NH 4 OH aqueous solution at a rate of 3.38 L / hr, and perform a coprecipitation reaction at 50 °C and below pH 11.6 for 48 hours to produce a cathode active material precursor having a composition of Ni 0.95 Co 0.02 Mn 0.03 (OH) 2 .

[0148] Mix the cathode active material precursor, LiOH, Al(OH) 3 , ZrO 2 in a molar ratio of 1:1.05:0.015:0.004, and calcine at 735 °C in an oxygen atmosphere for 27 hours to produce a cathode active material (average particle size (D 50 ): 15 μm). Here, the cathode active material contains 4000 ppm of zirconium and 4000 ppm of aluminum based on the total weight.

[0149] Comparative Example 3 In the same manner as in Example 1, a cathode active material precursor having a composition of Ni 0.936 Co 0.02 Mn 0.04 Zr 0.004 (OH) 2 was produced.

[0150] The positive electrode active material precursor and LiOH were mixed at a molar ratio of 1:1.05 and calcined at 755 °C in an oxygen atmosphere for 27 hours to produce a positive electrode active material (average particle size (D 50 ): 13 μm). Here, the positive electrode active material contains 4000 ppm of zirconium based on the total weight.

[0151] Comparative Example 4 NiSO 4 4, CoSO 4 4, MnSO 4 4, and AlSO 4 4 were mixed in deionized water in an amount such that the molar ratio of nickel:cobalt:manganese:aluminum was 92.5:2:6:1.5 to prepare a transition metal aqueous solution with a concentration of 2.4 M. Also, an aqueous NaOH solution with a concentration of 25 wt% and an aqueous NH 4 4OH solution with a concentration of 9 wt% were prepared. For reference, the AlSO 4 4 was added so that the aluminum content was 4000 ppm based on the total weight of the positive electrode active material precursor to be produced.

[0152] After putting 82.8 L of deionized water into the reactor, nitrogen gas was purged into the reactor at a rate of 20 L / min to remove dissolved oxygen in the water and make the inside of the reactor a non-oxidizing atmosphere. Next, 158 mL of the NaOH aqueous solution and 6812 mL of the NH 4 4OH aqueous solution were added, and then stirred at a stirring speed of 250 rpm at 50 °C to adjust the pH inside the reactor to pH 12.0 - 12.2.

[0153] Thereafter, while stirring at a stirring speed of 650 rpm, the transition metal aqueous solution was continuously fed into the reactor at a rate of 23.9 L / hr, the NaOH aqueous solution at a rate of 14.4 L / hr, and the NH 4 4OH aqueous solution at a rate of 3.38 L / hr, and a coprecipitation reaction was carried out at 50 °C and below pH 11.6 for 48 hours to produce a positive electrode active material precursor having a composition of Ni 0.925 xCo 0.02 yMn 0.04 zAl 0.015 (OH) 2 w.

[0154] The positive electrode active material precursor, LiOH, and ZrO 2 were mixed at a molar ratio of 1:1.05:0.004 and fired at 755°C in an oxygen atmosphere for 27 hours to produce a positive electrode active material (average particle size (D 50 ): 13 μm). Here, the positive electrode active material contains 4000 ppm of zirconium and 4000 ppm of aluminum with respect to the total weight.

[0155] Experimental examples Experimental Example 1: Composition Analysis of the Surface and Interior of the Positive Electrode Active Material Using EPMA (Electron Probe MicroAnalyzer) (JXA - 8350F, manufactured by JEOL Ltd.) (acceleration voltage: 15 kV, probe current: 100 nA), the content (wt%) of Al and Zr elements present on the surface and inside of the positive electrode active materials of Example 1, Comparative Example 1, and Comparative Example 4 was confirmed and shown in Table 1. On the other hand, when confirming the content of Al and Zr elements present inside the positive electrode active material, the positive electrode active material was cut using ion milling (IM4000, manufactured by HITACHI Ltd.), and then the cross-section was analyzed.

[0156] Specifically, the content of elements present on the surface of the positive electrode active materials of Example 1, Comparative Example 1, and Comparative Example 4 is the value obtained by EPMA Mapping the entire image of the surface of the positive electrode active material of Example 1 in (A) of Figure 1, the value obtained by EPMA Mapping the entire image of the surface of the positive electrode active material of Comparative Example 1 in (A) of Figure 2, and the value obtained by EPMA Mapping the entire image of the surface of the positive electrode active material of Comparative Example 4 in (A) of Figure 3. Also, the content of elements present inside the positive electrode active materials of Example 1, Comparative Example 1, and Comparative Example 4 is the average value of the values obtained by EPMA Mapping the inside of the red squares in the image of the cross-section of the positive electrode active material of Example 1 in (B) of Figure 1, the average value of the values obtained by EPMA Mapping the inside of squares 1 to 6 in the image of the cross-section of the positive electrode active material of Comparative Example 1 in (B) of Figure 2, and the average value of the values obtained by EPMA Mapping the inside of squares 1 to 8 in the image of the cross-section of the positive electrode active material of Comparative Example 4 in (B) of Figure 3.

[0157] On the one hand, (A) in FIG. 1 is an EPMA Mapping image of the surface of the positive electrode active material of Example 1, and (B) in FIG. 1 is an EPMA Mapping image of the cross-section of the positive electrode active material of Example 1. (A) in FIG. 2 is an EPMA Mapping image of the surface of the positive electrode active material of Comparative Example 1, and (B) in FIG. 2 is an EPMA Mapping image of the cross-section of the positive electrode active material of Comparative Example 1. Further, (A) in FIG. 3 is an EPMA Mapping image of the surface of the positive electrode active material of Comparative Example 4, and (B) in FIG. 3 is an EPMA Mapping image of the cross-section of the positive electrode active material of Comparative Example 4.

[0158]

Table 1

[0159] Referring to FIGS. 1 to 3 and Table 1, it can be confirmed that in the positive electrode active material of Example 1, there is less zirconium present in an aggregated state on the surface, and the content of each of aluminum and zirconium present inside is higher than the content of each of aluminum and zirconium present on the surface. In comparison, in the positive electrode active materials of Comparative Example 1 and Comparative Example 4, it can be confirmed that there is more zirconium present in an aggregated state on the surface, and more aluminum and zirconium elements are present on the surface of the positive electrode active material than in the examples.

[0160] Experimental Example 2: Evaluation of Battery Performance Lithium secondary batteries were manufactured using the positive electrode active materials produced in Examples 1 to 3 and Comparative Examples 1 to 4, and for each lithium secondary battery, the initial efficiency, initial resistance (DCIR), capacity retention rate, resistance increase rate, and DSC onset temperature were evaluated.

[0161] Specifically, each of the positive electrode active materials produced in Examples 1 to 3 and Comparative Examples 1 to 4 was mixed with SuperC65 conductive material and KF1120 binder in a weight ratio of 96.5:1.5:2.0 in an NMP solvent to produce a positive electrode slurry. The positive electrode slurry was applied to one side of an aluminum current collector, dried at 130°C, and then rolled to produce a positive electrode. On the other hand, a Li metal disk was used as the negative electrode active material. After manufacturing an electrode assembly with a separator interposed between the positive electrode and the negative electrode manufactured above, this was positioned inside a battery case, and then an electrolytic solution was injected into the case to manufacture a lithium secondary battery. Here, as the electrolytic solution, an electrolytic solution in which 1M of LiPF 6 was dissolved in an EC / EMC / DMC (3 / 3 / 4, vol%) organic solvent was injected to manufacture a lithium secondary battery.

[0162] The lithium secondary batteries manufactured as described above were each charged at a constant current of 0.2C to 4.25V at 25°C and discharged at a constant current of 0.2C to 2.5V to obtain an initial charge capacity and an initial discharge capacity. The percentage of the initial discharge capacity with respect to the initial charge capacity was defined as the initial efficiency (%) and shown in Table 2 below. Here, the current and voltage at 60 seconds after the start of discharge were measured, and the initial resistance value was calculated by the formula R = I / V and shown in Table 2 below.

[0163] In addition, each of the lithium secondary batteries manufactured as described above was charged at a constant current of 0.33C to 4.25V at 45°C and discharged at a constant current of 0.33C to 2.5V. One cycle was defined as one cycle, and 30 cycles were repeated. The percentage of the discharge capacity of the 30th cycle with respect to the discharge capacity of the first cycle was defined as the capacity retention rate (%) and shown in Table 2 below. The resistance of the 30th cycle with respect to the resistance of the first cycle was defined as the resistance increase rate (%) and shown in Table 2 below. For reference, the resistance value was obtained by measuring the current and voltage at 60 seconds after the start of discharge in each cycle and calculating using the formula R = I / V.

[0164] Then, the thermal stability was evaluated as follows. Specifically, each of the lithium secondary batteries manufactured as described above was charged to 4.25 V at a constant current of 0.2C at 25°C, discharged to 2.5 V at a constant current of 0.2C, and then charged to 4.25 V at a constant current of 0.2C again. After decomposition, only the positive electrode was separated and placed inside the DSC battery case. After that, an electrolytic solution (an electrolytic solution in which 1M LiPF 6 was dissolved in an organic solvent of EC / EMC / DMC (3 / 3 / 4, vol%)) was introduced so as to be 30 parts by weight with respect to 100 parts by weight of the total positive electrode, and a DSC battery was manufactured. The evaluation of thermal stability was carried out while raising the temperature from 25°C to 400°C at a rate of 10°C / min. The highest value of the first exothermic peak generated while raising the temperature was taken as the Onset peak, and the Onset temperature (Onset Temp.) is shown in Table 2 below.

[0165]

Table 2

[0166] Referring to Table 2 above, it can be confirmed that the batteries containing the positive electrode active materials of Examples 1 to 3 have high initial efficiency, low initial resistance, and excellent cycle characteristics and thermal stability. Specifically, it can be confirmed that the battery containing the positive electrode active material of Example 1 has higher initial efficiency, lower initial resistance, and lower resistance increase rate compared to the batteries containing the positive electrode active materials of Comparative Examples 1 and 4 which only differ in the doping method. Also, it can be confirmed that the battery containing the positive electrode active material of Example 2 also has higher initial efficiency, lower initial resistance, and lower resistance increase rate compared to the battery containing the positive electrode active material of Comparative Example 2 which only differs in the doping method.

[0167] This is because, when zirconium is doped into the composite transition metal hydroxide precursor first, that is, when zirconium is doped first during the production of the composite transition metal hydroxide, not only the distribution of zirconium but also the distribution of aluminum introduced in the step of mixing the precursor and the lithium-containing raw material and firing can be adjusted. As a result, a positive electrode active material is produced in which the weight ratio of aluminum present inside to aluminum present on the surface is greater than 1.0, and the weight ratio of zirconium present inside to zirconium present on the surface is greater than 1.0.

Claims

1. (A) A step of producing a composite transition metal hydroxide containing zirconium by performing a coprecipitation reaction while introducing a transition metal-containing solution containing at least one selected from nickel, cobalt, and manganese, a zirconium-containing raw material substance, an ammonium cation complexing agent, and a basic solution into a reactor; (B) A step of producing a lithium composite transition metal oxide by mixing the composite transition metal hydroxide containing zirconium with a lithium-containing raw material substance and an aluminum-containing raw material substance and firing them, The method for producing a positive electrode active material, wherein the lithium composite transition metal oxide contains at least one selected from nickel, cobalt, and manganese, zirconium, and aluminum.

2. The method for producing a positive electrode active material according to Claim 1, wherein the zirconium-containing raw material substance is at least one selected from zirconium hydroxide, zirconium sulfate, zirconium acetate, zirconium nitrate, zirconium halide, zirconium sulfide, and zirconium oxyhydroxide.

3. The method for producing a positive electrode active material according to Claim 1, wherein the zirconium-containing raw material substance is introduced so that the zirconium content is 1000 ppm to 9000 ppm with respect to the total weight of the composite transition metal hydroxide containing zirconium.

4. The method for producing a positive electrode active material according to Claim 1, wherein the aluminum-containing raw material substance is at least one selected from aluminum hydroxide, aluminum oxide, aluminum sulfate, aluminum acetate, aluminum nitrate, aluminum halide, aluminum sulfide, and aluminum oxyhydroxide.

5. The method for producing a positive electrode active material according to Claim 1, wherein the aluminum-containing raw material substance is introduced so that the aluminum content is 1000 ppm to 9000 ppm with respect to the total weight of the lithium composite transition metal oxide.

6. The method for producing a positive electrode active material according to Claim 1, wherein the firing in step (B) is performed at a temperature of 700°C to 800°C.

7. A lithium composite transition metal oxide containing at least one selected from nickel, cobalt, and manganese, zirconium, and aluminum, wherein the weight ratio of aluminum present inside to aluminum present on the surface is more than 1.0, A positive electrode active material having a weight ratio of zirconium present inside to zirconium present on the surface exceeding 1.

0. **Claim 8** The positive electrode active material according to claim 7, wherein the lithium composite transition metal oxide contains 1000 ppm to 9000 ppm of zirconium based on the total weight. **Claim 9** The positive electrode active material according to claim 7, wherein the lithium composite transition metal oxide contains 1000 ppm to 9000 ppm of aluminum based on the total weight. **Claim 10** The positive electrode active material has an average particle size (D ５０ ) of 3 μm to 20 μm, and is the positive electrode active material according to claim 7. **Claim 11** A positive electrode containing the positive electrode active material according to any one of claims 7 to 10. **Claim 12** A lithium secondary battery containing the positive electrode according to claim 11.

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