Positive electrode active material for lithium ion batteries, positive electrode for lithium ion batteries, lithium ion battery, method for producing precursor of positive electrode active material for lithium ion batteries, and method for producing positive electrode active material for lithium ion batteries

Abstract

Provided are: a positive electrode active material for lithium ion batteries, which exhibits good battery characteristics while containing Ca; a positive electrode for lithium ion batteries; a lithium ion battery; a method for producing a precursor of the positive electrode active material for lithium ion batteries; and a method for producing the positive electrode active material for lithium ion batteries.　The positive electrode active material for lithium ion batteries is represented by the composition formula LiaNi(1-b-c-d)CobMncCadO2 (in the formula, 0.98≤a≤1.09, 0.06≤b≤0.21, 0.02≤c≤0.32, and 0.000002≤d≤0.0007), has a 50% cumulative volume particle size D50 of 3.0-11.0 μm, a tap density of 2.0-2.6 g / cc, and a c-axis lattice constant of 14.180-14.255 Å.

Description

Positive electrode active material for lithium ion battery, positive electrode for lithium ion battery, lithium ion battery, method for manufacturing precursor of positive electrode active material for lithium ion battery, and method for manufacturing positive electrode active material for lithium ion battery

[0001] The present invention relates to a positive electrode active material for a lithium ion battery, a positive electrode for a lithium ion battery, a lithium ion battery, a method for producing a precursor of a positive electrode active material for a lithium ion battery, and a method for producing a positive electrode active material for a lithium ion battery.

[0002] In recent years, with the rapid spread of small electronic devices such as mobile phones and laptops, the demand for non-aqueous electrolyte secondary batteries as rechargeable power sources has been growing rapidly. As the positive electrode active material for non-aqueous electrolyte secondary batteries, lithium-cobalt composite oxides such as lithium cobalt oxide (LiCoO), lithium-nickel composite oxides such as lithium nickel oxide (LiNiO), and lithium-manganese composite oxides such as lithium manganese oxide (LiMnO) are widely used.

[0003] However, nickel and cobalt are relatively expensive metals, and cobalt in particular is known to be a metal with unstable supply and demand due to the limited number of countries where it is produced. Therefore, in recent years, as disclosed in Patent Document 1, attempts have been made to recover metal components such as lithium, nickel, and cobalt at high purity from discarded electrodes and discarded batteries and recycle them into positive electrode active materials.

[0004] Special Publication No. 2022-532575 Publication No. 11-354118

[0005] Although the demand for positive electrode active materials for lithium-ion secondary batteries is increasing, there is a problem in that excellent positive electrode active materials have variations in cycle performance and storage stability depending on the purity of the synthetic raw materials and the refining conditions. For this reason, as disclosed in Patent Document 2, it is necessary to control the purity of the positive electrode active material.

[0006] Discarded electrodes and batteries contain various metals in the can body and flame retardant materials used to prevent fire, and recovering high-purity nickel, cobalt, and lithium requires significant refining costs, resulting in high production costs for the positive electrode active material. Calcium (Ca) in particular is difficult to purify and extract, and its complete removal requires significant recycling costs.

[0007] Thus, from the viewpoint of controlling the purity in the positive electrode active material and improving battery characteristics, it is desirable to eliminate impurities such as Ca. However, on the other hand, when recovering high-purity nickel, cobalt, and lithium for recycling discarded electrodes and waste batteries, the cost of removing Ca becomes an issue.

[0008] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a positive electrode active material for a lithium ion battery that contains Ca and exhibits good battery characteristics, a positive electrode for a lithium ion battery, a lithium ion battery, a method for producing a precursor of a positive electrode active material for a lithium ion battery, and a method for producing a positive electrode active material for a lithium ion battery.

[0009] The present invention, which was completed based on the above findings, is defined as follows: 1. Composition formula: Li a Ni (1-b-c-d) Co b Mn c Ca d 1. A positive electrode active material for a lithium ion battery, having a BET specific surface area of ​​0.20 to 0.80 m, a 50% cumulative volume particle size D50 of 3.0 to 11.0 μm, a tap density of 2.0 to 2.6 g / cc, and a c-axis lattice constant of 14.180 to 14.255 Å, and a BET specific surface area of ​​0.20 to 0.80 m. 2 / g of the positive electrode active material for a lithium ion battery according to 1 above. 3. A positive electrode for a lithium ion battery comprising the positive electrode active material for a lithium ion battery according to 1 or 2 above. 4. A lithium ion battery comprising the positive electrode and negative electrode for a lithium ion battery according to 3 above. 5. A method for producing a lithium ion battery comprising the steps of: using an aqueous solution containing (a) a nickel salt, (b) a cobalt salt, (c) a manganese salt, and (d) a calcium salt; and (e) a basic aqueous solution containing ammonia and / or a basic aqueous solution of an alkali metal as a reaction solution; and carrying out a crystallization reaction while controlling the pH of the reaction solution to 10.0 to 11.5, the ammonium ion concentration to 7 to 20 g / L, and the solution temperature to 59 to 61°C, wherein the composition formula is Ni (1-b-c-d) Co b Mn c Ca d (OH)2 (wherein 0.06≦b≦0.21, 0.02≦c≦0.32, and 0.00001≦d≦0.0007), and has a 50% cumulative volume particle size D50 of 3.0 to 11.0 μm, a tap density of 1.8 to 2.4 g / cc, and a BET specific surface area of ​​4.0 to 12.0 m 2 6. A method for producing a precursor of a positive electrode active material for a lithium ion battery, wherein the precursor produced by the method for producing a precursor of a positive electrode active material for a lithium ion battery described in 5 above and a lithium source are mixed together to form a cathode active material having a total atomic number of metals consisting of Ni, Co, and Mn (Me n ) and the number of lithium atoms (Li n ) and the ratio (Li n / Me n ) to be 0.98 to 1.09 to form a lithium mixture; and firing the lithium mixture in air or an oxygen atmosphere at 450 to 750°C for 2 to 15 hours, and then further firing it at 700 to 900°C for 2 to 15 hours.

[0010] According to the present invention, it is possible to provide a positive electrode active material for a lithium ion battery that contains Ca and exhibits good battery characteristics, a positive electrode for a lithium ion battery, a lithium ion battery, a method for producing a precursor of a positive electrode active material for a lithium ion battery, and a method for producing a positive electrode active material for a lithium ion battery.

[0011] Next, the embodiments for carrying out the present invention will be described in detail. It should be understood that the present invention is not limited to the following embodiments, and that appropriate design changes, improvements, etc. may be made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0012] (Positive electrode active material for lithium ion battery) The positive electrode active material for lithium ion battery according to the embodiment of the present invention has the composition formula: Li a Ni (1-b-c-d) Co b Mn c Ca d O2 (wherein, 0.98≦a≦1.09, 0.06≦b≦0.21, 0.02≦c≦0.32, and 0.000002≦d≦0.0007). In the composition formula of the positive electrode active material, a, which indicates the lithium composition, is controlled to satisfy the condition of 0.98≦a≦1.09. Because a, which indicates the lithium composition, is 0.98 or more, it is possible to suppress the reduction of nickel due to lithium deficiency. Furthermore, because a, which indicates the lithium composition, is 1.09 or less, it is possible to suppress residual alkaline components, such as lithium carbonate and lithium hydroxide, present on the surface of the positive electrode active material particles, which may become resistance components when the material is used as a battery.

[0013] In the positive electrode active material for lithium ion batteries according to the embodiment of the present invention, the nickel composition in the composition formula is controlled to 1-b-c-d (0.4693≦1-b-c-d≦0.919998), and since the nickel composition is 0.4693 or more, good battery capacity can be obtained for lithium ion batteries. Furthermore, since the nickel composition is 0.919998 or less, the crystal structure is stable and the expansion and contraction behavior of the crystal lattice due to insertion and extraction of lithium during charge and discharge can be reduced, thereby improving cycle characteristics.

[0014] In the positive electrode active material for a lithium-ion battery according to an embodiment of the present invention, the sum of b, which represents the cobalt composition, c, which represents the manganese composition, and d, which represents the calcium composition, satisfies 0.080002≦b+c+d≦0.5307 in the composition formula, thereby improving cycle characteristics and reducing the expansion and contraction behavior of the crystal lattice due to the insertion and extraction of lithium during charge and discharge. If the sum of the cobalt composition, manganese composition, and calcium composition exceeds 0.5307, the amounts of cobalt, manganese, and calcium added may be too large, resulting in a significant decrease in initial discharge capacity or may be disadvantageous in terms of cost.

[0015] In the lithium-ion battery positive electrode active material according to an embodiment of the present invention, d, which indicates the calcium composition, is controlled to 0.000002≦d≦0.0007. Because d, which indicates the calcium composition, is 0.000002 or greater, cycle characteristics are improved and the expansion and contraction behavior of the crystal lattice due to lithium insertion and extraction during charge and discharge can be reduced. When d, which indicates the calcium composition, exceeds 0.0007, the amount of calcium added is too large, resulting in a significant decrease in initial discharge capacity. Thus, the lithium-ion battery positive electrode active material according to an embodiment of the present invention contains Ca, yet the battery characteristics of lithium-ion batteries using the same are excellent. Therefore, when recovering high-purity nickel, cobalt, and lithium for recycling discarded electrodes and waste batteries, the cost of removing Ca can be reduced, and a lithium-ion battery with excellent battery characteristics can be produced using the lithium-ion battery positive electrode active material.

[0016] The positive electrode active material for a lithium ion battery according to the embodiment of the present invention may be in the form of secondary particles formed by agglomeration of a plurality of primary particles, with some primary particles not agglomerated as secondary particles. The shapes of the primary particles constituting the secondary particles and the primary particles present alone are not particularly limited, and may be various shapes, such as substantially spherical, substantially elliptical, substantially plate-like, or substantially needle-like. The form in which the plurality of primary particles are agglomerated is also not particularly limited, and may be various forms, such as agglomeration in random directions or agglomeration approximately uniformly radially from the center to form substantially spherical or substantially elliptical secondary particles.

[0017] The positive electrode active material for a lithium ion battery according to an embodiment of the present invention has a 50% cumulative volume particle size D50 of 3.0 to 11.0 μm. Here, the 50% cumulative volume particle size D50 is the volume particle size at 50% accumulation in a volume-based cumulative particle size distribution curve. If the 50% cumulative volume particle size D50 of the positive electrode active material for a lithium ion battery is less than 3.0 μm, the tap density decreases, resulting in a decrease in energy density per volume. If the 50% cumulative volume particle size D50 of the positive electrode active material for a lithium ion battery exceeds 11.0 μm, the number of coarse particles increases, resulting in poor applicability when the slurried positive electrode active material is applied to a current collector. The 50% cumulative volume particle size D50 of the positive electrode active material for a lithium ion battery is preferably 7.0 to 10.0 μm. The 50% cumulative volume particle size D50 was measured by first dispersing 100 mg of a positive electrode active material sample (powder) using a Microtrac laser diffraction particle size distribution analyzer "MT3300EXII" at a 50% flow rate under 40 W ultrasonic irradiation for 60 seconds, and then measuring the particle size distribution to obtain a volume-based cumulative particle size distribution curve. Next, in the obtained cumulative particle size distribution curve, the volume particle size at 50% accumulation can be used as the 50% cumulative volume particle size D50 of the positive electrode active material powder. The aqueous solvent used in the measurement was passed through a 0.02 μm filter, with a solvent refractive index of 1.333, particle permeability conditions of 1.81, and shape of asphericity. The measurement range was 0.021 to 2000 μm, and the measurement time was 30 seconds.

[0018] The positive electrode active material for a lithium ion battery according to an embodiment of the present invention has a tap density of 2.0 to 2.6 g / cc. A positive electrode active material with a tap density of 2.0 g / cc or higher can form a battery with a high energy density per volume. The tap density of the positive electrode active material is preferably 2.1 to 2.6 g / cc, and more preferably 2.3 to 2.6 g / cc. The tap density of the positive electrode active material is measured, for example, by placing 5 g of the positive electrode active material (powder) into a 10 cc graduated cylinder, placing it in a powder density measuring instrument "KYT-4000K" manufactured by Seishin Enterprise Co., Ltd., and tapping 1,500 times with a stroke length of 55 mm, followed by reading the graduations on the graduated cylinder. Next, the "sample amount (5 g) / graduated cylinder graduation reading (cc)" is calculated, and this is taken as the tap density (g / cc).

[0019] The positive electrode active material for a lithium ion battery according to an embodiment of the present invention has a c-axis lattice constant controlled to 14.180 to 14.255 Å. When the c-axis lattice constant of the positive electrode active material is 14.180 Å or greater, the crystal structure of the positive electrode active material for a lithium ion battery can be stabilized, ensuring Li insertion and desorption. When the c-axis lattice constant of the positive electrode active material exceeds 14.255 Å, the crystal lattice is distorted, reducing the mobility of Li and thereby reducing the load characteristics, which may result in a deterioration in the charge and discharge capacity of the lithium ion battery. The c-axis lattice constant of the positive electrode active material is preferably 14.183 to 14.248 Å. The c-axis lattice constant of the positive electrode active material can be measured, for example, using the following XRD diffractometer under the following conditions. XRD diffractometer: SmartLab (Rigaku Corporation) Radiation source: CuKα (λ=1.5406 Å) A sample (positive electrode active material) was applied to a glass sample holder (2 cm × 1.5 cm, depth 0.3 mm). Detector: D / tex. Measurement range: 2θ=10° to 80°. Scan axis: 2θ / θ, scan speed: 1 degree min. -1Step width: 0.01 degree Slit width: IS (DS) 1 / 4°, RS1 10 mm, RS2 10 mm The c-axis lattice constant can be calculated using analytical software "PDXL, manufactured by Rigaku Corporation" from the peaks derived from a total of nine crystal planes: (003), (101), (012), (104), (015), (107), (018), (110), and (113) in the XRD diffraction pattern measured under the above conditions.

[0020] The positive electrode active material for a lithium ion battery according to an embodiment of the present invention has a BET specific surface area of ​​0.20 to 0.80 m 2 / g. The BET specific surface area is preferably 0.20 m 2 When the BET specific surface area is 0.80 m / g or more, the contact area of ​​the positive electrode active material is increased, and the Li ion conductivity is improved. Therefore, it is possible to manufacture a high-capacity lithium ion battery. 2 If the BET specific surface area is more than 0.3 to 0.70 m / g, the precipitation reaction of lithium ions from the residual alkali in the positive electrode active material is accelerated during repeated charge and discharge. The precipitated lithium compounds become the internal resistance of the battery, reducing the charge and discharge capacity. 2 / g is more preferable. The BET specific surface area can be measured by the following method. That is, first, 1.0 g of the positive electrode active material (powder) is weighed into a glass cell, set in a degassing device, and the glass cell is filled with nitrogen gas. After that, the cell is heat-treated in a nitrogen gas atmosphere at 40°C for 20 minutes to degas the sample. Thereafter, the glass cell containing the degassed sample (powder) is set in a specific surface area measuring device "Monosorb Model MS-21" manufactured by Quantachrome, and the specific surface area X is measured by the BET method (single-point method) while flowing a He:70 at%-N2:30 at% mixed gas as the adsorption gas.

[0021] (Method for producing precursor of positive electrode active material for lithium ion battery) Next, a method for producing precursor of positive electrode active material for lithium ion battery according to an embodiment of the present invention will be described in detail. (1-b-c-d) Co b Mn c Ca d(OH)2 (wherein 0.06≦b≦0.21, 0.02≦c≦0.32, and 0.00001≦d≦0.0007), and has a 50% cumulative volume particle size D50 of 3.0 to 11.0 μm, a tap density of 1.8 to 2.4 g / cc, and a BET specific surface area of ​​4.0 to 12.0 m 2 / g. In a method for producing a precursor of a positive electrode active material for a lithium ion battery according to an embodiment of the present invention, first, aqueous solutions containing (a) a nickel salt, (b) a cobalt salt, (c) a manganese salt, and (d) a calcium salt are prepared, and (e) a basic aqueous solution containing ammonia and / or a basic aqueous solution of an alkali metal is prepared. (a) Examples of nickel salts include nickel sulfate, nickel nitrate, or nickel chloride. (b) Examples of cobalt salts include cobalt sulfate, cobalt nitrate, or cobalt chloride. (c) Examples of manganese salts include manganese sulfate, manganese nitrate, or manganese chloride. (d) Examples of calcium salts include calcium sulfate, calcium nitrate, or calcium chloride. The calcium salt may be added as a raw material or may be mixed in as an impurity. (e) Examples of basic aqueous solutions containing ammonia include an ammonia solution, an ammonium sulfate solution, an ammonium carbonate solution, and an ammonium chloride solution. Examples of basic aqueous solutions of alkali metals include aqueous solutions of sodium hydroxide, potassium hydroxide, carbonates, etc. Examples of the aqueous carbonate solution include aqueous solutions using salts of carbonate groups, such as aqueous sodium carbonate solution, aqueous potassium carbonate solution, aqueous sodium hydrogen carbonate solution, and aqueous potassium hydrogen carbonate solution.

[0022] The composition of the aqueous solution can be adjusted appropriately depending on the composition of the precursor to be produced, but is preferably (a) an aqueous solution containing 30 to 150 g / L of nickel ions, (b) an aqueous solution containing 3 to 25 g / L of cobalt ions, (c) an aqueous solution containing 1 to 32 g / L of manganese ions, (d) an aqueous solution containing 0.003 to 0.06 g / L of calcium ions, or (e) a basic aqueous solution containing 7 to 28 mass % of ammonia and / or a basic aqueous solution with an alkali metal concentration of 10 to 30 mass %.

[0023] Next, the aqueous solution containing the above-mentioned (a) nickel salt, (b) cobalt salt, (c) manganese salt, and (d) calcium salt, and the aqueous solution containing (e) ammonia-containing basic aqueous solution and / or alkali metal basic aqueous solution are used as reaction solutions, and a crystallization reaction is carried out while controlling the pH of the reaction solution to 10.0 to 11.5, the ammonium ion concentration to 7 to 20 g / L, and the solution temperature to 59 to 61° C. At this time, chemical solutions may be sent to the reaction tank from three tanks: a tank containing a mixed aqueous solution of nickel salt, cobalt salt, manganese salt, and calcium salt, a tank containing ammonia-containing basic aqueous solution, and a tank containing an alkali metal basic aqueous solution. By carrying out the crystallization reaction while controlling the pH of the reaction solution during the coprecipitation reaction between 10.0 and 11.5, the ammonium ion concentration between 7 and 20 g / L, and the solution temperature between 59 and 61°C, the metal solubility in the reaction solution can be controlled, producing particles with uniformly dispersed calcium, thereby producing a precursor for the positive electrode active material according to an embodiment of the present invention with excellent discharge characteristics. Furthermore, by optimizing the reaction conditions for the metal hydroxide precursor as described above, adhesion of impurities to the surface of the positive electrode active material obtained after calcination is effectively suppressed, eliminating the need for cleaning. Furthermore, the need for a chelating agent or metal oxide coating during the coprecipitation reaction is eliminated. As a result, production efficiency is improved.

[0024] (Method for manufacturing a positive electrode active material for a lithium ion battery) Next, a method for manufacturing a positive electrode active material for a lithium ion battery according to an embodiment of the present invention will be described in detail. In the method for manufacturing a positive electrode active material for a lithium ion battery according to an embodiment of the present invention, first, a lithium source is added to the precursor of the positive electrode active material for a lithium ion battery according to an embodiment of the present invention prepared as described above, in which the sum of the number of atoms of metals consisting of Ni, Co, and Mn (Me n ) and the number of lithium atoms (Li n ) and the ratio (Li n / Me n ) is 0.98 to 1.09 to form a lithium mixture. Examples of the lithium source include lithium carbonate and lithium hydroxide. As a mixing method, it is preferable to adjust the mixing ratio of each raw material and dry mix it using a Henschel mixer, automatic mortar, V-type mixer, or the like.

[0025] Next, the lithium mixture is calcined in an air atmosphere, preferably an oxygen atmosphere, at 450 to 750° C. for 2 to 15 hours in the air or oxygen atmosphere, and then further calcined at 700 to 900° C. for 2 to 15 hours. Thereafter, if necessary, the calcined body can be crushed using, for example, a pulverizer or the like to obtain a powder of the positive electrode active material.

[0026] (Positive electrode for lithium ion battery and lithium ion battery) The positive electrode for lithium ion battery according to the embodiment of the present invention has a structure in which a positive electrode mixture prepared by mixing the positive electrode active material for lithium ion battery having the above-described configuration, a conductive additive, and a binder is provided on one or both sides of a current collector. The lithium ion battery according to the embodiment of the present invention includes a positive electrode for lithium ion battery having such a configuration and a known negative electrode for lithium ion battery.

[0027] Examples of conductive additives include metal-based conductive additives (aluminum, stainless steel (SUS), silver, gold, copper, titanium, etc.), carbon-based conductive additives (graphite and carbon black (acetylene black, ketjen black, furnace black, channel black, thermal lamp black), etc.), and mixtures thereof. These conductive additives may be used alone or in combination of two or more. They may also be used as alloys or metal oxides. Among these, from the viewpoint of electrical stability, more preferred are aluminum, stainless steel, silver, gold, copper, titanium, carbon-based conductive additives, and mixtures thereof, even more preferred are silver, gold, aluminum, stainless steel, and carbon-based conductive additives, and particularly preferred are carbon-based conductive additives. Furthermore, these conductive additives may be particulate ceramic materials or resin materials coated with a conductive material (preferably a metal one of the above-mentioned conductive additives) by plating or the like. The shape (form) of the conductive additive is not limited to a particulate form, and may be a form other than a particulate form, such as carbon nanofibers or carbon nanotubes, which are so-called filler-based conductive additives in practical use.

[0028] Examples of binders include substances commonly used in positive electrode mixtures for lithium ion batteries, but copolymers having a structure derived from vinylidene fluoride, polyvinylidene fluoride (PVDF), copolymers or homopolymers having a structure derived from tetrafluoroethylene (TEF), and copolymers or homopolymers having a structure derived from hexafluoropropylene (HFP) are preferred. Specific examples include PVDF-HFP, PVDF-HFP-TEF, PVDF-TEF, and TEF-HFP.

[0029] The positive electrode mixture is prepared by mixing a positive electrode active material for a lithium ion battery, a conductive additive, and a binder in a solvent to form a positive electrode mixture slurry, which is then applied to one or both sides of a current collector and dried or otherwise provided on the current collector to form a positive electrode active material layer.

[0030] As the solvent for the positive electrode mixture slurry, known organic solvents such as hydrocarbon organic solvents, amide compounds, lactam compounds, urea compounds, organic sulfur compounds, and cyclic organic phosphorus compounds can be used alone or as a mixed solvent. Examples of hydrocarbon organic solvents that can be used include saturated hydrocarbons, unsaturated hydrocarbons, and aromatic hydrocarbons. Examples of saturated hydrocarbons include hexane, pentane, 2-ethylhexane, heptane, decane, and cyclohexane. Examples of unsaturated hydrocarbons include hexene, heptene, and cyclohexene. Examples of aromatic hydrocarbons include toluene, xylene, decalin, and 1,2,3,4-tetrahydronaphthalene. Of these, toluene and xylene are particularly preferred.

[0031] Materials constituting the current collector include metal materials such as copper, aluminum, titanium, stainless steel, nickel, and alloys thereof, as well as baked carbon, conductive polymer materials, conductive glass, etc. Among these, aluminum is more preferable from the viewpoints of weight reduction, corrosion resistance, and high conductivity. Furthermore, the current collector is preferably a resin current collector made of a conductive polymer material. The shape of the current collector is not particularly limited, and may be a sheet-like current collector made of the above material, or a sediment layer made of fine particles composed of the above material. The thickness of the current collector is not particularly limited, but is preferably 1 to 30 μm. Examples of conductive polymer materials that can be used to constitute the resin current collector include conductive polymers and resins to which a conductive material has been added as needed.

[0032] From the viewpoint of battery performance, the thickness of the positive electrode for a lithium ion battery is preferably 10 to 100 μm, and more preferably 20 to 50 μm.

[0033] Lithium-ion batteries using a lithium-ion battery positive electrode are produced by combining a counter electrode with a negative electrode, placing them together with a separator in a cell container, injecting an electrolyte, and sealing the cell container. Alternatively, a bipolar electrode can be produced by forming a positive electrode on one side of a current collector and a negative electrode on the other, stacking the bipolar electrode with a separator, placing it in a cell container, injecting an electrolyte, and sealing the cell container.

[0034] The negative electrode may include a negative electrode active material, a conductive additive, a current collector, etc. As the negative electrode active material, known negative electrode active materials for lithium ion batteries can be used, and examples thereof include carbon-based materials (graphite, non-graphitizable carbon, amorphous carbon, burned resins (e.g., phenolic resins, furan resins, etc., which are burned and carbonized), cokes (e.g., pitch coke, needle coke, petroleum coke, etc.), and carbon fibers), silicon-based materials (silicon, silicon oxide (SiO x), silicon-carbon composites (carbon particles whose surfaces are coated with silicon and / or silicon carbide, silicon particles or silicon oxide particles whose surfaces are coated with carbon and / or silicon carbide, and silicon carbide, etc.) and silicon alloys (silicon-aluminum alloys, silicon-lithium alloys, silicon-nickel alloys, silicon-iron alloys, silicon-titanium alloys, silicon-manganese alloys, silicon-copper alloys, silicon-tin alloys, etc.), conductive polymers (e.g., polyacetylene and polypyrrole), metals (tin, aluminum, zirconium, titanium, etc.), metal oxides (titanium oxide and lithium-titanium oxide, etc.) and metal alloys (e.g., lithium-tin alloys, lithium-aluminum alloys, lithium-aluminum-manganese alloys, etc.), and mixtures of these with carbon-based materials, etc. Examples of the conductive additive include the same conductive additives as those used in the positive electrode described above.

[0035] The current collector may be the same as the current collector constituting the positive electrode described above, and is preferably copper from the viewpoints of weight reduction, corrosion resistance, and high conductivity. A resin current collector may also be used, and the same current collector as the current collector constituting the positive electrode described above can be suitably used. The thickness of the current collector is not particularly limited, but is preferably 10 to 60 μm.

[0036] Examples of the separator include known separators for lithium ion batteries, such as porous films made of polyethylene or polypropylene, laminated films of porous polyethylene film and porous polypropylene, nonwoven fabrics made of synthetic fibers (polyester fibers, aramid fibers, etc.) or glass fibers, and those having ceramic fine particles such as silica, alumina, or titania attached to the surface thereof.

[0037] The following examples are provided to provide a better understanding of the present invention and its advantages, but the present invention is not limited to these examples.

[0038] Example 1 First, a 1.5 mol / L mixed metal salt solution was prepared by weighing out predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 50:20:30. The Ca concentration of this mixed metal salt solution was 0.006 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed to a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 10.6 and the ammonium ion concentration was 10.3 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade in the reaction vessel was set to 1000 rpm, and the liquid temperature in the reaction vessel was maintained at 60°C using a water jacket. Nitrogen gas was also introduced into the reaction vessel to prevent oxidation of the coprecipitate produced by the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the resulting precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) of the number of lithium (Li) atoms to the sum of the number of metal atoms consisting of Ni, Co, and Mn in the precursor of the positive electrode active material was 1.06, where Me is the sum of the number of atoms, and the precursor was mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina sagger and calcined in a muffle furnace under air at 750°C for 2 hours, then heated to 900°C and maintained at that temperature for 8 hours to obtain a positive electrode active material.

[0039] Example 2 First, a 1.5 mol / L mixed metal salt solution was prepared by weighing out predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 50:20:30. The Ca concentration of this mixed metal salt solution was 0.007 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed to a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 10.4 and the ammonium ion concentration was 11.5 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade in the reaction vessel was 1000 rpm, and the liquid temperature in the reaction vessel was maintained at 60°C using a water jacket. Nitrogen gas was also introduced into the reaction vessel to prevent oxidation of the coprecipitate produced by the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the resulting precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) of the number of lithium (Li) atoms to the sum of the number of metal atoms consisting of Ni, Co, and Mn in the precursor of the positive electrode active material, Me, was 1.09. The mixture was mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina sagger and calcined in a muffle furnace under air at 750°C for 2 hours, then heated to 900°C and maintained at that temperature for 8 hours to obtain a positive electrode active material.

[0040] Example 3 First, a 1.5 mol / L mixed metal salt solution was prepared by weighing out predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 50:20:30. The Ca concentration of this mixed metal salt solution was 0.007 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed to a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 10.3 and the ammonium ion concentration was 8.2 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade in the reaction vessel was 1000 rpm, and the liquid temperature in the reaction vessel was maintained at 60°C using a water jacket. Nitrogen gas was also introduced into the reaction vessel to prevent oxidation of the coprecipitate produced by the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the resulting precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) of the number of lithium (Li) atoms to the sum of the number of metal atoms consisting of Ni, Co, and Mn in the precursor of the positive electrode active material, Me, was 1.06, and the mixture was mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina sagger and calcined in a muffle furnace under air at 750°C for 2 hours, then heated to 880°C and maintained at that temperature for 8 hours to obtain a positive electrode active material.

[0041] Example 4 First, a 1.5 mol / L mixed metal salt solution was prepared by weighing out predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 50:20:30. The Ca concentration of this mixed metal salt solution was 0.006 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed to a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 10.1 and the ammonium ion concentration was 11.2 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade in the reaction vessel was 1000 rpm, and the liquid temperature in the reaction vessel was maintained at 60°C using a water jacket. Nitrogen gas was also introduced into the reaction vessel to prevent oxidation of the coprecipitate produced by the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the resulting precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) of the number of lithium (Li) atoms to the sum of the number of metal atoms consisting of Ni, Co, and Mn in the precursor of the positive electrode active material was 1.06, where Me is the sum of the number of atoms, and the precursor was mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina sagger and calcined in a muffle furnace under air at 750°C for 2 hours, then heated to 900°C and maintained at that temperature for 8 hours to obtain a positive electrode active material.

[0042] (Example 5) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 50:20:30. The Ca concentration of this mixed metal salt solution was 0.006 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed to a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 10.2 and the ammonium ion concentration was 11.3 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade in the reaction vessel was 1000 rpm, and the liquid temperature in the reaction vessel was maintained at 60°C using a water jacket. Nitrogen gas was also introduced into the reaction vessel to prevent oxidation of the coprecipitate produced by the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the resulting precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) of the number of lithium (Li) atoms to the sum of the number of metal atoms consisting of Ni, Co, and Mn in the precursor of the positive electrode active material, Me, was 1.06, and the mixture was mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina sagger and calcined in a muffle furnace under air at 750°C for 2 hours, then heated to 880°C and maintained at that temperature for 8 hours to obtain a positive electrode active material.

[0043] (Example 6) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing out predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 50:20:30. The Ca concentration of this mixed metal salt solution was 0.055 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed to a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 10.2 and the ammonium ion concentration was 10.7 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade in the reaction vessel was 1000 rpm, and the liquid temperature in the reaction vessel was maintained at 60°C using a water jacket. Nitrogen gas was also introduced into the reaction vessel to prevent oxidation of the coprecipitate produced by the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the resulting precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) of the number of lithium (Li) atoms to the sum of the number of metal atoms consisting of Ni, Co, and Mn in the precursor of the positive electrode active material, Me, was 1.06, and the mixture was mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina sagger and calcined in a muffle furnace under air at 750°C for 2 hours, then heated to 880°C and maintained at that temperature for 8 hours to obtain a positive electrode active material.

[0044] Example 7 First, a 1.5 mol / L mixed metal salt solution was prepared by weighing predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 50:20:30. The Ca concentration of this mixed metal salt solution was 0.007 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed to a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 10.6 and the ammonium ion concentration was 14.8 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade in the reaction vessel was 1000 rpm, and the liquid temperature in the reaction vessel was maintained at 60°C using a water jacket. Nitrogen gas was also introduced into the reaction vessel to prevent oxidation of the coprecipitate produced by the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the resulting precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) of the number of lithium (Li) atoms to the sum of the number of metal atoms consisting of Ni, Co, and Mn in the precursor of the positive electrode active material, Me, was 1.06, and the mixture was mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina sagger and calcined in a muffle furnace under air at 750°C for 2 hours, then heated to 880°C and maintained at that temperature for 8 hours to obtain a positive electrode active material.

[0045] (Example 8) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing out predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 82:15:3. The Ca concentration of this mixed metal salt solution was 0.005 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed to a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 11.2 and the ammonium ion concentration was 13.5 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade in the reaction vessel was 1000 rpm, and the liquid temperature in the reaction vessel was maintained at 60°C using a water jacket. Furthermore, nitrogen gas was introduced into the reaction vessel to prevent oxidation of the coprecipitate produced in the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the resulting precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, lithium hydroxide and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) of the number of lithium (Li) atoms to the sum of the number of metal atoms consisting of Ni, Co, and Mn in the precursor of the positive electrode active material, Me, was 1.01, and the mixture was mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina sagger and calcined in a muffle furnace under an oxygen atmosphere at 500°C for 8 hours, then heated to 740°C and maintained at that temperature for 4 hours to obtain a positive electrode active material.

[0046] Example 9 First, a 1.5 mol / L mixed metal salt solution was prepared by weighing out predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 90:7:3. The Ca concentration of this mixed metal salt solution was 0.004 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed into a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 11.0 and the ammonium ion concentration was 7.2 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. The reaction vessel was maintained at a stirring blade rotation speed of 820 rpm, and the liquid temperature in the reaction vessel was maintained at 60°C using a water jacket. Nitrogen gas was introduced into the reaction vessel to prevent oxidation of the coprecipitate produced by the crystallization reaction. The gas introduced into the reaction vessel is not limited to the nitrogen gas mentioned above, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 ° C. for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, when the sum of the number of atoms of metals consisting of Ni, Co, and Mn in the precursor of the positive electrode active material is Me, the ratio (Li / Me) to the number of lithium (Li) atoms was 1.01. The mixture was mixed with lithium hydroxide and the precursor of the positive electrode active material, and mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina sagger and calcined in a muffle furnace under an oxygen atmosphere at 500 ° C. for 8 hours, then heated to 720 ° C. and held at that temperature for 4 hours to obtain a positive electrode active material.

[0047] (Example 10) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing out predetermined amounts of nickel sulfate, cobalt sulfate, and manganese sulfate so that the Ni:Co:Mn ratio was 90:7:3. The Ca concentration of this mixed metal salt solution was 0.004 g / L. Next, the mixed metal salt solution, ammonia water, and a 20% by mass aqueous sodium hydroxide solution were fed to a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel was 11.0 and the ammonium ion concentration was 10.0 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade in the reaction vessel was 820 rpm, and the liquid temperature in the reaction vessel was maintained at 60 °C using a water jacket. Furthermore, nitrogen gas was introduced into the reaction vessel to prevent oxidation of the coprecipitate produced in the crystallization reaction. The gas introduced into the reaction vessel is not limited to nitrogen gas, and any gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide, can be used. Next, the resulting precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box dryer. This produced a precursor of a positive electrode active material. Next, lithium hydroxide and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) of the number of lithium (Li) atoms to the sum of the number of metal atoms consisting of Ni, Co, and Mn in the precursor of the positive electrode active material was 0.98, and the mixture was mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina sagger and calcined in a muffle furnace under an oxygen atmosphere at 500°C for 8 hours, then heated to 720°C and held at that temperature for 4 hours to obtain a positive electrode active material.

[0048] (Composition) The compositions of the precursors and positive electrode active material powders of Examples 1 to 10 were measured as follows. Regarding the nickel, cobalt, and manganese compositions, a specified amount of each precursor and each positive electrode active material sample (powder) was weighed out, decomposed by an alkali fusion method, and then analyzed using an inductively coupled plasma optical emission spectroscopy (ICP-OES) "PS7800" manufactured by Hitachi High-Tech Corporation. Regarding the calcium compositions of the precursors and positive electrode active materials, a specified amount of each precursor and each positive electrode active material sample (powder) was weighed out, dissolved by acid decomposition, and then analyzed using an ICP mass spectrometer (ICP-MS) "SPQ9700" manufactured by SII NanoTechnology.

[0049] (Average Particle Size D50) The average particle size D50 of each of the precursors and positive electrode active material powders of Examples 1 to 10 was measured as follows. 100 mg of each obtained precursor and positive electrode active material sample (powder) was dispersed by irradiating with 40 W ultrasonic waves for 60 seconds at a 50% flow rate using a Microtrac laser diffraction particle size distribution analyzer "MT3300EXII." The particle size distribution was measured, and a volume-based cumulative particle size distribution curve was obtained. In the obtained cumulative particle size distribution curve, the volume particle size at 50% accumulation was taken as the 50% cumulative volume particle size D50 (average particle size D50) of the positive electrode active material powder. The water-soluble solvent used in the measurement was passed through a 0.02 μm filter, the solvent refractive index was 1.333, the particle permeability conditions were permeable, the particle refractive index was 1.81, the shape was aspherical, the measurement range was 0.021 to 2000 μm, and the measurement time was 30 seconds.

[0050] (Tap Density) The tap density of each of the precursors and positive electrode active material powders of Examples 1 to 10 was measured as follows. Five grams of each of the obtained precursors and positive electrode active material samples (powder) was placed in a 10 cc graduated cylinder and placed in a powder density measuring instrument "KYT-4000K" manufactured by Seishin Enterprise Co., Ltd. After tapping 1,500 times with a stroke length of 55 mm, the graduations on the graduated cylinder were read. Next, the "sample amount (5 g) / graduated cylinder graduation reading (cc)" was calculated, and this was taken as the tap density (g / cc).

[0051] (BET Specific Surface Area) The BET specific surface area of ​​each of the precursors and positive electrode active material powders of Examples 1 to 10 was measured as follows. 1.0 g of each of the obtained precursors and positive electrode active material samples (powder) was weighed into a glass cell, set in a degassing device, and filled with nitrogen gas. The glass cell was then heat-treated at 40°C for 20 minutes in a nitrogen gas atmosphere to degas the sample. The glass cell containing the degassed sample (powder) was then set in a Quantachrome specific surface area measuring device "Monosorb Model MS-21," and the specific surface area X was measured by the BET method (single-point method) while flowing a He:70 at%-N:30 at% mixed gas as the adsorption gas.

[0052] (c-Axis Lattice Constant) The c-axis lattice constant of each of the positive electrode active material powders of Examples 1 to 10 was measured as follows. The following XRD diffractometer and conditions were used: XRD diffractometer: SmartLab (manufactured by Rigaku Corporation) Radiation source: CuKα (λ=1.5406 Å) A sample (positive electrode active material) was applied to a glass sample holder (2 cm × 1.5 cm, depth 0.3 mm) Detector: D / tex Measurement range: 2θ=10° to 80° Scan axis: 2θ / θ, scan speed: 1 degree min -1 Step width: 0.01 degree Slit width: IS (DS) 1 / 4°, RS1 10 mm, RS2 10 mm The c-axis lattice constant was calculated using analytical software "PDXL, manufactured by Rigaku Corporation" from peaks derived from a total of nine crystal planes: (003), (101), (012), (104), (015), (107), (018), (110), and (113) in the XRD diffraction pattern measured under the above conditions.

[0053] (Discharge Capacity) The discharge capacity of each of the positive electrode active material powders of Examples 1 to 10 was measured as follows. The resulting positive electrode active material was weighed out with a conductive material (acetylene black) and a binder (polyvinylidene fluoride) in a ratio of 90:5:5. The binder was dissolved in an organic solvent (N-methylpyrrolidone). The positive electrode material and the conductive material were mixed to form a slurry, which was then applied to an Al foil, dried, and pressed to form a positive electrode. Subsequently, a 2032-type coin cell for evaluation was fabricated using a Li counter electrode. The electrolyte was a 1M LiPF6 solution in EC-DMC (3:7), and the initial battery characteristics (charge capacity, discharge capacity, and charge / discharge characteristics) were measured at 25°C. The charge / discharge conditions were: charge condition: CC / CV 4.3 V, 0.1 C; discharge condition: CC 0.05 C, up to 3.0 V. The manufacturing conditions and evaluation results of Examples 1 to 10 are shown in Tables 1 and 2.

[0054]

[0055]

[0056] (Evaluation Results) The positive electrode active materials of Examples 1 to 10 all had the following composition formula. Note that the "Li / Me ratio" in Tables 1 and 2 indicates the composition ratio of Li to the total of Ni, Co, and Mn in the positive electrode active material. Composition formula: Li a Ni (1-b-c-d) Co b Mn c Ca d O2 (wherein, 0.98≦a≦1.09, 0.06≦b≦0.21, 0.02≦c≦0.32, 0.000002≦d≦0.0007). Furthermore, the positive electrode active materials of Examples 1 to 10 all had a 50% cumulative volume particle size D50 of 3.0 to 11.0 μm, a tap density of 2.0 to 2.6 g / cc, and a c-axis lattice constant of 14.180 to 14.255 Å, and exhibited good battery characteristics (discharge capacity).

Claims

1. Composition formula: Li a Ni (1-b-c-d) Co b Mn c Ca d O2 (wherein 0.98≦a≦1.09, 0.06≦b≦0.21, 0.02≦c≦0.32, and 0.000002≦d≦0.0007), having a 50% cumulative volume particle size D50 of 3.0 to 11.0 μm, a tap density of 2.0 to 2.6 g / cc, and a c-axis lattice constant of 14.180 to 14.255 Å.

2. BET specific surface area is 0.20 to 0.80 m 2 The positive electrode active material for a lithium ion battery according to claim 1, wherein the Li-ion battery positive electrode active material has a molecular weight of 1.001 or more.

3. A positive electrode for a lithium ion battery comprising the positive electrode active material for a lithium ion battery according to claim 1 or 2.

4. A lithium ion battery comprising the positive electrode and the negative electrode for a lithium ion battery according to claim 3.

5. The method includes a step of performing a crystallization reaction using an aqueous solution containing (a) a nickel salt, (b) a cobalt salt, (c) a manganese salt, and (d) a calcium salt, and (e) a basic aqueous solution containing ammonia and / or an alkaline aqueous solution of an alkali metal as a reaction solution, while controlling the pH of the reaction solution to 10.0 to 11.5, the ammonium ion concentration to 7 to 20 g / L, and the solution temperature to 59 to 61° C., (1-b-c-d) Co b Mn c Ca d (OH)2 (wherein, 0.06≦b≦0.21, 0.02≦c≦0.32, and 0.00001≦d≦0.0007), the 50% cumulative volume particle size D50 is 3.0 to 11.0 μm, the tap density is 1.8 to 2.4 g / cc, and the BET specific surface area is 4.0 to 12.0 m. 2 / g of a precursor of a positive electrode active material for a lithium ion battery.

6. A precursor produced by the method for producing a precursor for a positive electrode active material for a lithium ion battery according to claim 5 and a lithium source are mixed together to obtain a lithium-ion battery positive electrode active material having a total number of atoms of metals consisting of Ni, Co and Mn (Me n ) and the number of lithium atoms (Li n ) and the ratio (Li n / Me n ) is 0.98 to 1.09 to form a lithium mixture; and baking the lithium mixture in air or an oxygen atmosphere at 450 to 750° C. for 2 to 15 hours, and then baking it at 700 to 900° C. for 2 to 15 hours.

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