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

Abstract

The present application provides 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 the positive electrode active material for a lithium ion battery, and a method for producing the positive electrode active material for a lithium ion battery, the positive electrode active material for a lithium ion battery containing Al and exhibiting good battery characteristics. A positive electrode active material for a lithium ion battery, which is represented by the compositional formula Lia Ni (1-b-c-d) CobMncAldO2 (in the formula, 0.98 < = a < = 1.09, 0.06 < = b < = 0.21, 0.02 < = c < = 0.32, and 0.0000003 < = d < = 0.007). The present invention relates to a binder for a lithium ion secondary battery, characterized in that the binder has a 50% cumulative volume particle size D50 of 3.0-11.0 [mu] m, a tap density of 2.0-2.6 g / cc, and a c-axis lattice constant of 14.180-14.255.

Description

TECHNICAL FIELD

[0001] The present application 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. BACKGROUND

[0002] In recent years, with the rapid increase in small electronic devices such as portable telephones and notebook computers, there has been a sharp increase in demand for nonaqueous electrolyte secondary batteries as power sources that can be charged and discharged. As positive electrode active materials for nonaqueous electrolyte secondary batteries, lithium cobalt complex oxides represented by lithium cobaltate (LiCoO2) and lithium nickel complex oxides represented by lithium nickelate (LiNiO2), lithium manganese complex oxides represented by lithium manganate (LiMnO2), and the like are widely used.

[0003] However, nickel and cobalt are relatively expensive metals, and in particular, cobalt is a metal for which there are limited producing countries and which is known to be unstable in terms of supply and demand. Therefore, in recent years, as disclosed in Patent Literature 1, attempts have been made to recover metal components such as lithium, nickel, and cobalt from waste electrodes and waste batteries at high purity and to recycle them again as positive electrode active materials.

[0004] PRIOR ART DOCUMENTS PATENT LITERATURE Patent Literature 1: Japanese Patent Application Laid-Open No. 2022-532575 Patent Literature 2: Japanese Patent Application Laid-Open No. H11-354118 SUMMARY

[0005] PROBLEMS TO BE SOLVED BY THE INVENTION There are increasing demands for positive electrode active materials for lithium ion secondary batteries, but in terms of excellent positive electrode active materials, there are problems in that the cycle performance and the storage properties fluctuate depending on the purity of the synthesis raw material and the conditions of the purification. Therefore, as disclosed in Patent Literature 2, it is necessary to control the purity in the positive electrode active material.

[0006] In terms of waste electrodes and waste batteries, various metals are present in the shell including aluminum (Al) that is a shell that wraps around the periphery, aluminum foil that is an electrode, a can, and a flame retardant material for preventing ignition. Therefore, in order to recover nickel, cobalt, and lithium at high purity, a large amount of purification cost is required, and as a result, the production cost of the positive electrode active material becomes high. In particular, with respect to Al, it is difficult to extract by purification, and in order to completely remove it, a corresponding recycling cost must be incurred.

[0007] Thus, from the viewpoint of improving battery characteristics by controlling the purity in the positive electrode active material, it is desired to remove impurities such as Al, but on the other hand, when recycling and recovering high-purity nickel, cobalt, and lithium from waste electrodes and waste batteries, the cost for removing Al becomes a problem.

[0008] The present application was completed in order to solve the above-described technical problem, and aims to provide a positive electrode active material for a lithium ion battery, a positive electrode for a lithium ion battery, a lithium ion battery, a production method of a precursor of a positive electrode active material for a lithium ion battery, and a production method of a positive electrode active material for a lithium ion battery, the positive electrode active material for a lithium ion battery containing Al and exhibiting good battery characteristics.

[0009] Solution to the problem The present application completed based on the above-described knowledge is defined below.

[0010] 1. A positive electrode active material for a lithium ion battery, represented by the composition formula: Li a Ni （1-b-c-d） Co b Mn c Al d O2 (in the formula, 0.98≤a≤1.09, 0.06≤b≤0.21, 0.02≤c≤0.32, 0.0000003≤d≤0.007), 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 A.

[0011] 2. The positive electrode active material for a lithium ion battery according to the above 1, wherein the BET specific surface area is 0.20 to 0.80 m 2 / g.

[0012] 3. A positive electrode for a lithium ion battery, comprising the positive electrode active material for a lithium ion battery according to the above 1 or 2.

[0013] 4. A lithium ion battery, comprising the positive electrode for a lithium ion battery according to the above 3 and a negative electrode.

[0014] 5. A production method of a precursor of a positive electrode active material for a lithium ion battery, comprising the step of: preparing a reaction solution from an aqueous solution containing an aqueous solution containing (a) a nickel salt, (b) a cobalt salt, (c) a manganese salt, and (d) an aluminum salt, and (e) an aqueous alkali solution containing ammonia and / or an aqueous alkali solution of an alkali metal, while controlling the pH in the reaction solution to be 10.0 to 11.5, controlling the ammonium ion concentration to be 7 to 20 g / L, and controlling the liquid temperature to be 59 to 61°C, and performing a crystallization reaction while controlling the pH, the ammonium ion concentration, and the liquid temperature, the precursor of the positive electrode active material for a lithium ion battery being represented by the composition formula: Ni （1-b-c-d）Co b Mn c Al d (OH)2 (in the formula, 0.06 ≤ b ≤ 0.21, 0.02 ≤ c ≤ 0.32, 0.0000003 ≤ d ≤ 0.007) represents, 50% cumulative volume particle size D50 is 3.0 to 11.0 μm, tap density is 1.8 to 2.4 g / cc, BET specific surface area is 4.0 to 12.0 m 2 / g.

[0015] 6. A method for producing a positive electrode active material for a lithium ion battery, comprising the steps of: mixing a precursor produced by the method for producing a precursor of a positive electrode active material for a lithium ion battery described in 5 and a lithium source in a manner such that the ratio (Li n / Me n ) of the number of atoms of lithium (Li n ) to the sum of the number of atoms of metals consisting of Ni, Co, and Mn (Me n ) becomes 0.98 to 1.09, to form a lithium mixture; and firing the lithium mixture in an atmosphere of air or oxygen at 450 to 750°C for 2 to 15 hours, and further firing at 700 to 900°C for 2 to 15 hours.

[0016] Effects of the Invention According to the present application, it is possible to provide 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, the positive electrode active material for a lithium ion battery containing Al and exhibiting good battery characteristics. DETAILED DESCRIPTION

[0017] The present application will be described in detail below. The present application is not limited to the following embodiments, and it should be understood that appropriate design changes, modifications, and the like can be made based on the common knowledge of those skilled in the art without departing from the spirit of the present application.

[0018] (Positive electrode active material for a lithium ion battery) The positive electrode active material for a lithium ion battery of the embodiments of the present application is represented by the compositional formula: Li a Ni （1-b-c-d） Co b Mn c Al dO2 (in the formula, 0.98≤a≤1.09, 0.06≤b≤0.21, 0.02≤c≤0.32, 0.0000003≤d≤0.007) represents this. Regarding the positive electrode active material, the 'a' representing the lithium composition in the composition formula is controlled to be 0.98≤a≤1.09. When the 'a' representing the lithium composition is 0.98 or higher, nickel reduction due to lithium deficiency can be suppressed. Furthermore, when the 'a' representing the lithium composition is 1.09 or lower, residual alkaline components such as lithium carbonate and lithium hydroxide present on the surface of the positive electrode active material particles, which may become resistive components during battery manufacturing, can be suppressed.

[0019] Regarding the positive electrode active material for lithium-ion batteries according to embodiments of the present invention, the nickel composition is controlled to be 1-b-c-d (0.463 ≤ 1-b-c-d ≤ 0.9199997) in the formula, and the nickel composition is 0.463 or higher, thus achieving good battery capacity for lithium-ion batteries. Furthermore, the nickel composition is 0.9199997 or lower, resulting in a stable crystal structure. By reducing the lattice expansion and contraction behavior caused by lithium insertion and extraction during charging and discharging, cycle characteristics can be improved.

[0020] Regarding the positive electrode active material for lithium-ion batteries according to embodiments of the present invention, the total of b (representing cobalt), c (representing manganese), and d (representing aluminum) in the composition formula is 0.0800003 ≤ b + c + d ≤ 0.537. Therefore, the cycle characteristics are improved, and the lattice expansion and contraction behavior caused by lithium insertion and extraction during charging and discharging is reduced. If the total of b (representing cobalt), c (representing manganese), and d (representing aluminum) exceeds 0.537, the addition of cobalt, manganese, and aluminum is excessive, which may significantly reduce the initial discharge capacity or be disadvantageous in terms of cost.

[0021] Regarding the positive electrode active material for lithium-ion batteries according to embodiments of the present invention, the aluminum composition d is controlled to be 0.0000003 ≤ d ≤ 0.007. When the aluminum composition d is 0.0000003 or higher, the cycle characteristics are improved, and the lattice expansion and contraction behavior caused by lithium insertion and extraction during charging and discharging is reduced. If the aluminum composition d exceeds 0.007, the amount of aluminum added is excessive, and the initial discharge capacity is significantly reduced. Thus, although the positive electrode active material for lithium-ion batteries according to embodiments of the present invention contains Al, lithium-ion batteries using this positive electrode active material exhibit excellent battery characteristics. Therefore, when recycling high-purity nickel, cobalt, and lithium as waste electrodes and waste batteries, the cost of removing Al can be suppressed, and lithium-ion batteries with excellent battery characteristics can be manufactured using the aforementioned positive electrode active material.

[0022] Regarding the positive electrode active material for lithium-ion batteries according to embodiments of the present invention, most of them have the form of secondary particles formed by the aggregation of multiple primary particles, and some may also have the form of primary particles that do not aggregate into secondary particles. There is no particular limitation on the shape of the primary particles constituting the secondary particles and the individual primary particles; for example, they can be various shapes such as approximately spherical, approximately elliptical, approximately plate-like, approximately needle-like, etc. Furthermore, there is no particular limitation on the form formed by the aggregation of multiple primary particles; for example, they can be various forms such as those aggregated in random directions, those aggregated radially from the center to form approximately spherical or approximately elliptical secondary particles, etc.

[0023] In the case of the positive electrode active material for lithium-ion batteries according to embodiments of the present invention, the 50% cumulative volumetric particle size D50 is 3.0 to 11.0 μm. Here, the 50% cumulative volumetric particle size D50 is the volumetric particle size at 50% accumulation in the cumulative particle size distribution curve based on volume. If the 50% cumulative volumetric particle size D50 of the positive electrode active material for lithium-ion batteries is less than 3.0 μm, the tap density decreases, and the energy density per unit volume decreases. If the 50% cumulative volumetric particle size D50 of the positive electrode active material for lithium-ion batteries exceeds 11.0 μm, coarse particles increase, and the coatability deteriorates when coating the slurry-formed positive electrode active material onto the current collector. The 50% cumulative volumetric particle size D50 of the positive electrode active material for lithium-ion batteries is preferably 7.0 to 10.0 μm. As a method for determining the aforementioned 50% cumulative volumetric particle size D50, firstly, 100 mg of a sample (powder) of the positive electrode active material was dispersed by irradiating it with 40 W ultrasound for 60 seconds at a flow rate of 50% using a Microtrac laser diffraction particle size distribution measuring device (MT3300EXII). The particle size distribution was then measured to obtain a volumetric cumulative particle size distribution curve. Next, the volumetric particle size at 50% accumulation can be set as the 50% cumulative volumetric particle size D50 of the positive electrode active material powder from the obtained cumulative particle size distribution curve. It should be noted that the water-soluble solvent used in the measurement was passed through a 0.02 μm filter. The solvent refractive index could be set to 1.333, the particle transmittance condition to transmittance, the particle refractive index to 1.81, the shape to non-spherical, the measurement range to 0.021–2000 μm, and the measurement time to 30 seconds.

[0024] Regarding the positive electrode active material for lithium-ion batteries according to embodiments of the present invention, the tap density is 2.0 to 2.6 g / cc. If the tap density of the positive electrode active material is 2.0 g / cc or higher, a battery with high energy density per unit volume can be constructed. The tap density of the positive electrode active material is preferably 2.1 to 2.6 g / cc, more preferably 2.3 to 2.4 g / cc. For example, regarding the tap density of the positive electrode active material, 5 g of positive electrode active material (powder) is added to a 10 cc graduated cylinder, and the cylinder is subjected to 1500 taps with a stroke length of 55 mm using a powder density meter "KYT-4000K" manufactured by SEISHIN Corporation. The graduated cylinder is then read. Next, the "sample input amount (5 g) / graduated cylinder reading (cc)" is calculated and set as the tap density (g / cc).

[0025] In the lithium-ion battery positive electrode active material according to embodiments of the present invention, the c-axis lattice constant is controlled to be 14.180 to 14.255 Å. If the c-axis lattice constant of the positive electrode active material is 14.180 Å or higher, the crystal structure of the positive electrode active material for lithium-ion batteries can be stabilized, ensuring the insertion and extraction of Li. If the c-axis lattice constant of the positive electrode active material exceeds 14.255 Å, lattice distortion occurs, and the charge / discharge capacity of the lithium-ion battery may deteriorate due to the decrease in load characteristics caused by the reduction in Li mobility. The c-axis lattice constant of the positive electrode active material is preferably 14.183 to 14.252 Å. The c-axis lattice constant of the positive electrode active material can be determined, for example, using the following XRD diffraction apparatus under the following conditions.

[0026] • XRD diffraction apparatus: SmartLab (manufactured by Rigaku Co., Ltd.)

[0027] • X-ray source: CuKα (λ = 1.5406 Å).

[0028] • Coat the sample (positive electrode active material) onto a glass sample holder (2cm×1.5cm, depth 0.3mm).

[0029] • Detector: D / tex.

[0030] • Measurement range: 2θ = 10°~80°.

[0031] • Scan axis: 2θ / θ, Scan speed: 1 degree / min -1 .

[0032] • Step width: 0.01 degrees.

[0033] • Slit width: IS (DS) 1 / 4°, RS1 10mm, RS2 10mm.

[0034] The c-axis lattice constant can be calculated using the analytical software "Rigaku, PDXL" based on the peaks of the XRD diffraction pattern obtained under the above conditions, originating from a total of 9 crystal planes (003), (101), (012), (104), (015), (107), (018), (110), and (113).

[0035] Regarding the positive electrode active material for lithium-ion batteries according to embodiments of the present invention, the BET specific surface area is preferably 0.20 to 0.80 m². 2 / g. If the specific surface area of ​​BET is 0.20m², then... 2 When the BET specific surface area exceeds 0.80 m² / g, the contact area of ​​the positive electrode active material increases, and the conductivity of Li ions becomes better. Therefore, high-capacity lithium-ion batteries can be manufactured. Furthermore, if the BET specific surface area exceeds 0.80 m² / g... 2 If the concentration of lithium ions is low (e.g.), repeated charge-discharge cycles will promote the precipitation of lithium ions from the residual alkali in the positive electrode active material. The precipitated lithium compounds become part of the battery's internal resistance, reducing its charge-discharge capacity. A more preferable BET specific surface area is 0.3–0.70 m² / g. 2 / g. The BET specific surface area can be determined by the following method. First, weigh 1.0g of the positive electrode active material (powder) into a glass cell, place it in a degassing device, fill the glass cell with nitrogen, and then degas it by heat treatment at 40°C for 20 minutes in a nitrogen atmosphere. Then, place the glass cell containing the degassed sample (powder) into a Quantachrome Monosorb Model MS-21 specific surface area measuring device, and measure the specific surface area X using the BET method (single-point method) while circulating a mixed gas of He: 70at% - N2: 30at% as the adsorption gas.

[0036] (Manufacturing method of precursors for positive electrode active materials for lithium-ion batteries) Next, the method for manufacturing the precursor of the positive electrode active material for lithium-ion batteries according to embodiments of the present invention will be described in detail.

[0037] The precursor of the positive electrode active material for lithium-ion batteries according to embodiments of the present invention has the following composition: Ni （1-b-c-d） Co b Mn c Al d (OH)₂ (in the formula, 0.06≤b≤0.21, 0.02≤c≤0.32, 0.0000003≤d≤0.007) indicates a 50% cumulative volumetric particle size D50 of 3.0–11.0 μm, a tap density of 1.8–2.4 g / cc, and a BET specific surface area of ​​4.0–12.0 m². 2 / g.

[0038] Regarding the method for manufacturing a precursor of a positive electrode active material for a lithium-ion battery according to an embodiment of the present invention, firstly, an aqueous solution containing (a) a nickel salt, (b) a cobalt salt, (c) a manganese salt, and (d) an aluminum salt, and (e) an alkaline aqueous solution containing ammonia and / or an alkaline aqueous solution containing an alkali metal, is prepared. Examples of (a) the nickel salt include nickel sulfate, nickel nitrate, or nickel hydrochloride. Examples of (b) the cobalt salt include cobalt sulfate, cobalt nitrate, or cobalt hydrochloride. Examples of (c) the manganese salt include manganese sulfate, manganese nitrate, or manganese hydrochloride. Examples of (d) the aluminum salt include aluminum sulfate, sodium aluminate, aluminum nitrate, or aluminum chloride. It should be noted that the aluminum salt can be added as a raw material or mixed in as an impurity. Examples of (e) the alkaline aqueous solution containing ammonia include aqueous solutions of ammonia, ammonium sulfate, ammonium carbonate, and ammonium hydrochloride. The alkaline aqueous solution containing an alkali metal can be an aqueous solution of sodium hydroxide, potassium hydroxide, carbonate, etc. Furthermore, examples of aqueous solutions of the carbonates include aqueous solutions of salts that use a carbonate group, such as sodium carbonate aqueous solution, potassium carbonate aqueous solution, sodium bicarbonate aqueous solution, and potassium bicarbonate aqueous solution.

[0039] Furthermore, the composition of the aqueous solution can be appropriately adjusted by the composition of the precursor used in its manufacture, 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 0.001 to 0.2 g / L of aluminum ions, (e) an alkaline aqueous solution containing 7 to 28% by mass of ammonia and / or an alkaline aqueous solution with an alkali metal concentration of 10 to 30% by mass.

[0040] Next, a reaction solution is prepared by combining an aqueous solution containing (a) nickel salt, (b) cobalt salt, (c) manganese salt, and (d) aluminum salt, and (e) an alkaline aqueous solution containing ammonia and / or an alkaline aqueous solution containing alkali metals. The pH of the reaction solution is controlled at 10.0–11.5, the ammonium ion concentration at 7–20 g / L, and the temperature at 59–61°C, while the crystallization reaction is carried out. At this time, the reagent solution can be transferred to the reaction tank from three separate tanks: one containing a mixed aqueous solution of nickel salt, cobalt salt, manganese salt, and aluminum salt; one containing an alkaline aqueous solution containing ammonia; and one containing an alkaline aqueous solution containing alkali metals. While controlling the pH of the reaction solution during the co-precipitation reaction to 10.0–11.5, the ammonium ion concentration to 7–20 g / L, and the liquid temperature to 59–61°C, a crystallization reaction is carried out. This allows for control of the metal solubility in the reaction solution, producing particles with uniform aluminum dispersion, and enabling the production of a precursor for the positive electrode active material of the embodiment of the present invention with excellent discharge characteristics. Furthermore, by optimizing the reaction conditions of the metal hydroxide as the precursor as described above, the adhesion of impurities to the surface of the positive electrode active material obtained after calcination is effectively suppressed, thus eliminating the need for cleaning. Moreover, chelating agents and metal oxide coatings used in the co-precipitation reaction are unnecessary. As a result, manufacturing efficiency is improved.

[0041] (Manufacturing method of positive electrode active material for lithium-ion batteries) 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. Regarding the method for manufacturing a positive electrode active material for a lithium-ion battery according to an embodiment of the present invention, firstly, lithium atoms (Li) are added to the precursor of the positive electrode active material for a lithium-ion battery prepared as described above. n The sum of the number of atoms of the metal composed of Ni, Co, and Mn (Me) n The ratio of (Li) n / Me n The lithium source is mixed in a ratio of 0.98 to 1.09 to form a lithium mixture. Examples of lithium sources include lithium carbonate or lithium hydroxide. As a mixing method, it is preferable to adjust the mixing ratio of each raw material and perform dry mixing using a Henschel mixer, an automatic mortar and pestle, or a V-type mixer.

[0042] Next, the lithium mixture is calcined in an atmospheric atmosphere, preferably an oxygen atmosphere, at 450–750°C for 2–15 hours, and then further calcined at 700–900°C for 2–15 hours. Then, as needed, the calcined body can be depolymerized, for example, by using an impact mill, to obtain a powder of the positive electrode active material.

[0043] (Positive electrode for lithium-ion batteries and lithium-ion batteries) The positive electrode for a lithium-ion battery according to embodiments of the present invention, for example, has a structure in which a positive electrode mixture prepared by mixing the above-described positive electrode active material, conductive additive, and binder is provided on one or both sides of the current collector. Furthermore, the lithium-ion battery according to embodiments of the present invention includes both a positive electrode for a lithium-ion battery with such a configuration and a known negative electrode for a lithium-ion battery.

[0044] Examples of conductive additives include metal-based conductive additives (aluminum, stainless steel (SUS), silver, gold, copper, and titanium, etc.), carbon-based conductive additives (graphite and carbon black (acetylene black, Ketjen black, furnace black, channel black, and thermal lamp black), etc.), and mixtures thereof. These conductive additives can be used individually or in combination of two or more. Furthermore, they can be used in the form of alloys or metal oxides. From the viewpoint of electrical stability, aluminum, stainless steel, silver, gold, copper, titanium, carbon-based conductive additives, and mixtures thereof are more preferred, silver, gold, aluminum, stainless steel, and carbon-based conductive additives are even more preferred, and carbon-based conductive additives are particularly preferred. In addition, these conductive additives can also be obtained by coating a conductive material (preferably a metallic substance from the aforementioned conductive additives) around a particle-based ceramic material or resin material through plating or the like. The shape (morphology) of the conductive additive is not limited to a particle shape; it can also be a shape other than a particle shape, such as carbon nanofibers or carbon nanotubes, which are practically used as so-called filler-based conductive additives.

[0045] As binders, examples include substances commonly used in positive electrode binders for lithium-ion batteries, preferably 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). Specifically, examples include PVDF-HFP, PVDF-HFP-TEF, PVDF-TEF, and TEF-HFP.

[0046] Regarding the positive electrode slurry, a positive electrode slurry is prepared by mixing positive electrode active material, conductive additives and binders in a solvent. After being coated on one or both sides of the current collector, it is dried and then deposited on the current collector to form a positive electrode active material layer.

[0047] As a solvent for the positive electrode slurry, known organic solvents, such as hydrocarbon-based organic solvents, amide compounds, lactam compounds, urea compounds, organosulfur compounds, and cyclic organophosphorus compounds, can be used as a single solvent or as a mixed solvent. As a hydrocarbon-based organic solvent, saturated hydrocarbons, unsaturated hydrocarbons, or aromatic hydrocarbons can be used. 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, decahydronaphthalene, and 1,2,3,4-tetrahydronaphthalene. Toluene and xylene are particularly preferred.

[0048] Examples of materials constituting the current collector include metallic materials such as copper, aluminum, titanium, stainless steel, nickel, and their alloys, as well as sintered carbon, conductive polymers, and conductive glass. Among these, aluminum is more preferred from the viewpoints of lightweight, corrosion resistance, and high conductivity. Furthermore, the current collector is preferably a resin current collector formed from a conductive polymer. The shape of the current collector is not particularly limited; it can be a sheet-like current collector formed from the aforementioned materials or a deposition layer formed from particles composed of the aforementioned materials. The thickness of the current collector is not particularly limited, but is preferably 1 to 30 μm. For example, conductive polymers or conductive polymers obtained by adding conductive materials to a resin as needed can be used as conductive polymers constituting the resin current collector.

[0049] From the perspective of battery performance, the thickness of the positive electrode for lithium-ion batteries is preferably 10 to 100 μm, and more preferably 20 to 50 μm.

[0050] A lithium-ion battery using a positive electrode is obtained by combining the positive electrode with the negative electrode, housing it together with a separator in a battery container, injecting electrolyte, and sealing the battery container. Alternatively, a bipolar electrode can be fabricated by forming a positive electrode on one side of the current collector and a negative electrode on the other side, then stacking the bipolar electrode with a separator and housing it in a battery container, injecting electrolyte, and sealing the battery container.

[0051] As a negative electrode, examples include negative electrode active materials, conductive additives, and current collectors. As a negative electrode active material, known lithium-ion battery negative electrode active materials can be used, including: carbon-based materials (graphite, non-graphitizable carbon, amorphous carbon, sintered resins (e.g., substances obtained by sintering and carbonizing phenolic resins and furan resins), coke-based materials (e.g., pitch coke, needle coke, and petroleum coke), and carbon fibers), and silicon-based materials (silicon, silicon oxide (SiO₂)). xThis includes silicon-carbon composites (substances obtained by coating the surface of carbon particles with silicon and / or silicon carbide, substances obtained by coating the surface of silicon particles or silicon oxide particles with carbon and / or silicon carbide, and silicon carbide, etc.), silicon alloys (silicon-aluminum alloys, silicon-lithium alloys, silicon-nickel alloys, silicon-iron alloys, silicon-titanium alloys, silicon-manganese alloys, silicon-copper alloys, and silicon-tin alloys, etc.), conductive polymers (e.g., polyacetylene and polypyrrole, etc.), metals (tin, aluminum, zirconium, and titanium, etc.), metal oxides (titanium oxides, lithium, titanium oxides, etc.), and metal alloys (e.g., lithium-tin alloys, lithium-aluminum alloys, and lithium-aluminum-manganese alloys, etc.), as well as mixtures thereof with carbon-based materials, etc. Furthermore, the conductive additive can preferably be the same conductive additive as the aforementioned positive electrode.

[0052] As the current collector, the same current collector as the one constituting the positive electrode described above can be used. From the viewpoints of lightweight, corrosion resistance, and high conductivity, copper is preferred. Alternatively, a resin current collector can also be used, and the same current collector as the one constituting the positive electrode described above is preferred. The thickness of the current collector is not particularly limited, but is preferably 10 to 60 μm.

[0053] Examples of separators for lithium-ion batteries include: porous membranes made of polyethylene or polypropylene, laminated membranes of porous polyethylene and porous polypropylene, nonwoven fabrics made of synthetic fibers (such as polyester fibers and aramid fibers) or glass fibers, and membranes obtained by attaching ceramic microparticles such as silica, alumina, and titanium dioxide to their surfaces.

[0054] Example The following are embodiments provided to better understand the present invention and its advantages, but the present invention is not limited to these embodiments.

[0055] (Example 1) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in a ratio of Ni:Co:Mn = 50:20:30. The Al concentration of this mixed metal salt solution was less than 0.001 g / L.

[0056] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 10.6 and an ammonium ion concentration of 10.3 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 1000 rpm, and a water jacket was used to maintain the liquid temperature in the reaction tank at 60°C.

[0057] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0058] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0059] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium carbonate and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.06. The mixture was then stirred in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 750°C under atmospheric conditions for 2 hours. The furnace was then heated to 900°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0060] (Example 2) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in a ratio of Ni:Co:Mn = 50:20:30. The Al concentration of this mixed metal salt solution was less than 0.001 g / L.

[0061] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 10.4 and an ammonium ion concentration of 11.5 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 1000 rpm, and the tank was kept at a temperature of 60°C using a water jacket.

[0062] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0063] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0064] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium carbonate and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.09. The mixture was then mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 750°C under atmospheric conditions for 2 hours. The furnace was then heated to 900°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0065] (Example 3) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in a ratio of Ni:Co:Mn = 50:20:30. The Al concentration of this mixed metal salt solution was less than 0.001 g / L.

[0066] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 10.3 and an ammonium ion concentration of 8.2 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 1000 rpm, and a water jacket was used to maintain the liquid temperature in the reaction tank at 60°C.

[0067] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0068] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0069] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium carbonate and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.06. The mixture was then mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 750°C under atmospheric atmosphere for 2 hours. The furnace was then heated to 880°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0070] (Example 4) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in a ratio of Ni:Co:Mn = 50:20:30. The Al concentration of this mixed metal salt solution was less than 0.001 g / L.

[0071] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 10.1 and an ammonium ion concentration of 11.2 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 1000 rpm, and the tank temperature was maintained at 60°C using a water jacket.

[0072] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0073] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0074] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium carbonate and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.06. The mixture was then mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 750°C under atmospheric atmosphere for 2 hours. The furnace was then heated to 900°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0075] (Example 5) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in a ratio of Ni:Co:Mn = 50:20:30. The Al concentration of this mixed metal salt solution was less than 0.001 g / L.

[0076] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 10.2 and an ammonium ion concentration of 11.3 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 1000 rpm, and a water jacket was used to maintain the liquid temperature in the reaction tank at 60°C.

[0077] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0078] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0079] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium carbonate and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.06. The mixture was then mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 750°C under atmospheric atmosphere for 2 hours. The furnace was then heated to 880°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0080] (Example 6) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in the ratio of Ni:Co:Mn = 49.5:20.1:30.3. The Al concentration of this mixed metal salt solution was 0.046 g / L.

[0081] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 10.2 and an ammonium ion concentration of 9.9 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 1000 rpm, and a water jacket was used to maintain the liquid temperature in the reaction tank at 60°C.

[0082] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0083] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0084] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium carbonate and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.06. The mixture was then mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 750°C under atmospheric atmosphere for 2 hours. The furnace was then heated to 880°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0085] (Example 7) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in the ratio of Ni:Co:Mn = 49.3:20.3:30.2. The Al concentration of this mixed metal salt solution was 0.06 g / L.

[0086] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 10.2 and an ammonium ion concentration of 11.1 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were rotated at 1000 rpm, and the tank temperature was maintained at 60°C using a water jacket.

[0087] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0088] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0089] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium carbonate and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.06. The mixture was then mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 750°C under atmospheric atmosphere for 2 hours. The furnace was then heated to 880°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0090] (Example 8) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in the ratio of Ni:Co:Mn = 49.0:20.4:30.0. The Al concentration of this mixed metal salt solution was 0.19 g / L.

[0091] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 10.2 and an ammonium ion concentration of 10.7 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 1000 rpm, and the tank was kept at a temperature of 60°C using a water jacket.

[0092] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0093] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0094] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium carbonate and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.06. The mixture was then mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 750°C under atmospheric atmosphere for 2 hours. The furnace was then heated to 880°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0095] (Example 9) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in a ratio of Ni:Co:Mn = 50:20:30. The Al concentration of this mixed metal salt solution was less than 0.001 g / L.

[0096] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 10.6 and an ammonium ion concentration of 14.8 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 1000 rpm, and the tank was kept at a temperature of 60°C using a water jacket.

[0097] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0098] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0099] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium carbonate and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.06. The mixture was then mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 750°C under atmospheric atmosphere for 2 hours. The furnace was then heated to 880°C and held at that temperature for 8 hours to obtain the positive electrode active material.

[0100] (Example 10) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in a ratio of Ni:Co:Mn = 82:15:3. The Al concentration of this mixed metal salt solution was less than 0.001 g / L.

[0101] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 11.2 and an ammonium ion concentration of 13.5 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 1000 rpm, and the tank was kept at a temperature of 60°C using a water jacket.

[0102] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0103] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0104] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium hydroxide and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.01. The mixture was then stirred in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 500°C under an oxygen atmosphere for 8 hours. The furnace was then heated to 740°C and held at that temperature for 4 hours to obtain the positive electrode active material.

[0105] (Example 11) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in a ratio of Ni:Co:Mn = 90:7:3. The Al concentration of this mixed metal salt solution was less than 0.001 g / L.

[0106] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 11.0 and an ammonium ion concentration of 7.2 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 820 rpm, and a water jacket was used to maintain the liquid temperature in the reaction tank at 60°C.

[0107] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0108] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0109] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium hydroxide and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 1.01. The mixture was then stirred in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 500°C under an oxygen atmosphere for 8 hours. The furnace was then heated to 720°C and held at that temperature for 4 hours to obtain the positive electrode active material.

[0110] (Example 12) First, a 1.5 mol / L mixed metal salt solution was prepared by weighing specified amounts of nickel sulfate, cobalt sulfate, and manganese sulfate in a ratio of Ni:Co:Mn = 90:7:3. The Al concentration of this mixed metal salt solution was less than 0.001 g / L.

[0111] Next, a mixed metal salt solution, ammonia, and a 20% (w / w) sodium hydroxide aqueous solution were introduced into the reaction tank equipped with stirring blades at a pH of 11.0 and an ammonium ion concentration of 10.0 g / L to induce a crystallization reaction, resulting in the precipitation of a nickel-cobalt-manganese composite hydroxide compound. At this time, the stirring blades in the reaction tank were set to rotate at 820 rpm, and a water jacket was used to maintain the liquid temperature in the reaction tank at 60°C.

[0112] In addition, nitrogen gas is introduced into the reaction tank to prevent the oxidation of the coprecipitate generated during the crystallization reaction. Nitrogen gas is not limited to nitrogen gas as long as the gas introduced into the reaction tank is a gas that does not promote oxidation, such as helium, neon, argon, or carbon dioxide.

[0113] Next, the obtained precipitate was filtered, washed with water, and dried using a box dryer at 120°C for 12 hours. This produced a precursor for the positive electrode active material.

[0114] Next, with the sum of the atomic numbers of the metals composed of Ni, Co, and Mn in the precursor of the positive electrode active material set as Me, lithium hydroxide and the precursor of the positive electrode active material were mixed with a lithium (Li) atomic number to Me ratio (Li / Me) of 0.98. The mixture was then mixed in an automatic mortar for 30 minutes to obtain a mixed powder. The mixed powder was then filled into an alumina crucible and sintered in a muffle furnace at 500°C in an oxygen atmosphere for 8 hours. The furnace was then heated to 720°C and held at that temperature for 4 hours to obtain the positive electrode active material.

[0115] (composition) The composition of the precursors and positive electrode active materials of Examples 1-12 was determined as follows.

[0116] For the nickel, cobalt, and manganese composition, a specified amount of each precursor and each positive electrode active material sample (powder) was measured, decomposed by alkaline melting method, and then the composition was analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES) "PS7800" manufactured by Hitachi High-Tech Co., Ltd.

[0117] In addition, for the aluminum composition of the precursors and positive electrode active materials, a specified amount of each precursor and positive electrode active material sample (powder) was measured, and after acid decomposition and solidification, the composition was analyzed using an ICP mass analyzer (ICP-MS) "SPQ9700" manufactured by SII Nano Technology.

[0118] (Average particle size D50) The average particle size D50 of the precursors and positive electrode active materials of Examples 1-12 was measured as follows.

[0119] 100 mg of each precursor and each positive electrode active material sample (powder) was dispersed using a Microtrac laser diffraction particle size distribution analyzer "MT3300EXII". The sample was irradiated with 40 W ultrasound for 60 seconds at 50% flow rate, and the particle size distribution was measured to obtain a volume-based cumulative particle size distribution curve. In the obtained cumulative particle size distribution curve, the volumetric particle size at 50% accumulation was defined as the 50% cumulative volumetric particle size D50 (average particle size D50) of the positive electrode active material powder. It should be noted that the water-soluble solvent was passed through a 0.02 μm filter, the solvent refractive index was set to 1.333, the particle transmittance condition was set to transmission, the particle refractive index was set to 1.81, the shape was set to non-spherical, the measurement range was set to 0.021–2000 μm, and the measurement time was set to 30 seconds.

[0120] (Tap density) The tap density of the precursors and positive electrode active materials of Examples 1-12 was measured as follows.

[0121] Five g of each precursor and positive electrode active material sample (powder) was added to a 10 cc graduated cylinder. The cylinder was then compacted using a SEISHIN KYT-4000K powder density meter, with a stroke length of 55 mm, for 1500 cycles. The graduated cylinder scale was then read. Next, the ratio of "sample input (5 g) / graduated cylinder scale reading (cc)" was calculated and set as the compacted density (g / cc).

[0122] (BET specific surface area) The BET specific surface area of ​​the precursors and positive electrode active materials of Examples 1-12 was measured as described below.

[0123] Weigh 1.0 g of each precursor and each positive electrode active material sample (powder) in a glass cell, place it in a degassing device, fill the glass cell with nitrogen, and degas it by heat treatment at 40°C for 20 minutes in a nitrogen atmosphere. Then, place the glass cell containing the degassed sample (powder) in a Quantachrome Monosorb Model MS-21 surface area measuring device, and measure the surface area X using the BET method (single-point method) while circulating a He: 70 at% - N2: 30 at% mixed gas as the adsorption gas.

[0124] (c-axis lattice constant) The c-axis lattice constants of the positive electrode active materials of Examples 1 to 12 were determined as follows.

[0125] Use the following XRD diffraction apparatus and conditions.

[0126] • XRD diffraction apparatus: SmartLab (manufactured by Rigaku Co., Ltd.)

[0127] • X-ray source: CuKα (λ = 1.5406 Å).

[0128] • Coat the sample (positive electrode active material) onto a glass sample holder (2cm×1.5cm, depth 0.3mm).

[0129] • Detector: D / tex.

[0130] • Measurement range: 2θ = 10°~80°.

[0131] • Scan axis: 2θ / θ, Scan speed: 1 degree / min -1 .

[0132] • Step width: 0.01 degrees.

[0133] • Slit width: IS (DS) 1 / 4°, RS1 10mm, RS2 10mm.

[0134] The c-axis lattice constant was calculated using the analytical software "Rigaku, PDXL" based on the peaks of the XRD diffraction pattern obtained under the above conditions, originating from a total of nine crystal planes: (003), (101), (012), (104), (015), (107), (018), (110), and (113).

[0135] (Discharge capacity) The discharge capacity of the positive electrode active material powders of Examples 1 to 12 was measured as follows.

[0136] The obtained positive electrode active material, conductive material (acetylene black), and binder (polyvinylidene fluoride) were weighed in a ratio of 90:5:5. The binder was dissolved in an organic solvent (N-methylpyrrolidone), and the positive electrode material and conductive material were mixed in. The mixture was then slurried, coated onto Al foil, dried, and pressed to form the positive electrode. Next, a 2032-type coin cell was fabricated for evaluation with Li as the counter electrode. The electrolyte used was a solution obtained by dissolving 1M LiPF6 in EC-DMC (3:7). The initial characteristics of the battery (charge capacity, discharge capacity, charge-discharge characteristics) were measured at 25°C. It should be noted that the charge-discharge conditions were: charging condition: CC / CV 4.3V, 0.1C; discharging condition: CC 0.05C, cutoff 3.0V.

[0137] The manufacturing conditions and evaluation results of Examples 1 to 12 described above are shown in Tables 1 and 2. (Evaluation Results) The positive electrode active materials in Examples 1 to 12 all have the following compositional formula. It should be noted that the "Li / Me ratio" in Tables 1 and 2 represents the compositional ratio of Li relative to the total of Ni, Co, and Mn in the positive electrode active material.

[0138] Composition formula: Li a Ni （1-b-c-d） Co b Mn c Al d O2 (In the formula, 0.98≤a≤1.09, 0.06≤b≤0.21, 0.02≤c≤0.32, 0.0000003≤d≤0.007.) In addition, the positive electrode active materials in Examples 1 to 12 all have 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 all have good battery characteristics (discharge capacity).

Claims

1. A positive electrode active material for lithium-ion batteries, comprising the following composition: Li a Ni （1-b-c-d） Co b Mn c Al d O2 indicates that In the formula, 0.98≤a≤1.09, 0.06≤b≤0.21, 0.02≤c≤0.32, 0.0000003≤d≤0.

007. The 50% cumulative volumetric particle size D50 is 3.0–11.0 μm, the tap density is 2.0–2.6 g / cc, and the c-axis lattice constant is 14.180–14.255 Å.

2. The positive electrode active material for lithium-ion batteries according to claim 1, wherein, The specific surface area of ​​BET is 0.20–0.80 m². 2 / g.

3. A positive electrode for a lithium-ion battery, comprising the positive electrode active material for a lithium-ion battery as described in claim 1 or 2.

4. A lithium-ion battery comprising a positive electrode and a negative electrode as described in claim 3.

5. A method for manufacturing a precursor of a positive electrode active material for lithium-ion batteries, comprising the following steps: The reaction solution is prepared by using aqueous solutions containing the following: an aqueous solution containing a nickel salt, b cobalt salt, c manganese salt, and d aluminum salt; and e an alkaline aqueous solution containing ammonia and / or an alkaline aqueous solution containing alkali metals. While maintaining the pH of the reaction solution at 10.0–11.5, the ammonium ion concentration at 7–20 g / L, and the liquid temperature at 59–61 °C, the crystallization reaction was carried out. The precursor of the positive electrode active material for the lithium-ion battery has the following composition: Ni （1-b-c-d） Co b Mn c Al d (OH)₂ represents, In the formula, 0.06≤b≤0.21, 0.02≤c≤0.32, 0.0000003≤d≤0.

007. The 50% cumulative volumetric particle size (D50) is 3.0–11.0 μm, the tap density is 1.8–2.4 g / cc, and the BET specific surface area is 4.0–12.0 m². 2 / g.

6. A method for manufacturing a positive electrode active material for lithium-ion batteries, comprising the following steps: The precursor and lithium source manufactured by the method for manufacturing a precursor of a positive electrode active material for a lithium-ion battery as described in claim 5 are combined with the lithium atomic number Li n Me n The ratio of Li n / Me n Mixed in a manner ranging from 0.98 to 1.09, a lithium mixture is formed; and The lithium mixture is calcined in an atmospheric or oxygen atmosphere at 450–750°C for 2–15 hours, and then further calcined at 700–900°C for 2–15 hours.

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