Cathode active material for lithium ion battery, cathode for lithium ion battery, lithium ion battery, method for manufacturing precursor of cathode active material for lithium ion battery, and method for manufacturing cathode active material for lithium ion battery

Abstract

To provide a cathode active material for a lithium ion battery exhibiting good battery characteristics while containing Al, a cathode for a lithium ion battery, a lithium ion battery, a method for manufacturing a precursor of a cathode active material for a lithium ion battery, and a method for manufacturing a cathode active material for a lithium ion battery.SOLUTION: A cathode active material for a lithium ion battery is represented by a composition formula: LiaNi(1-b-c-d)CobMncAldO2 (where 0.98≤a≤1.09, 0.06≤b≤0.21, 0.02≤c≤0.32, and 0.0000003≤d≤0.007), and has 50% cumulative volume particle size D50 of 3.0 to 11.0 μm, tap density of 2.0 to 2.6 g / cc, and a c-axis lattice constant of 14.180 to 14.255 Å.SELECTED DRAWING: None

Description

Technical Field

[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 manufacturing a precursor of a positive electrode active material for a lithium ion battery, and a method for manufacturing a positive electrode active material for a lithium ion battery.

Background Art

[0002] In recent years, with the rapid expansion of small electronic devices such as mobile phones and notebook computers, the demand for non-aqueous electrolyte secondary batteries as rechargeable power sources has been rapidly increasing. As the positive electrode active material of the non-aqueous electrolyte secondary battery, lithium cobalt composite oxides represented by lithium cobalt oxide (LiCoO 2 ), lithium nickel composite oxides represented by lithium nickel oxide (LiNiO 2 ), lithium manganese composite oxides represented by lithium manganate (LiMnO 2 ) and the like are widely used.

[0003] However, nickel and cobalt are relatively expensive metals, and in particular, cobalt has limited production countries and is known as a metal with unstable supply and demand. Therefore, in recent years, as disclosed in Patent Document 1, methods have been attempted to recover metal components such as lithium, nickel, and cobalt from waste electrodes and waste batteries with high purity and recycle them into positive electrode active materials again.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The requirements for the cathode active material of lithium-ion secondary batteries are increasing, but for excellent cathode active materials, there is a problem that the cycle performance and storage stability vary depending on the purity of the synthesis raw materials and the differences in purification conditions. Therefore, as disclosed in Patent Document 2, it is necessary to control the purity in the cathode active material.

[0006] Waste electrodes and waste batteries have, as an outer package that wraps around them, a housing containing aluminum (Al), an aluminum foil as an electrode, a can body, and various metals in a flame retardant material for preventing ignition. Therefore, in order to recover high-purity nickel, cobalt, and lithium, a great deal of purification costs are required, and as a result, the production cost of the cathode active material becomes high. In particular, regarding Al, purification extraction is difficult, and a corresponding recycling cost must be incurred to completely remove it.

[0007] Thus, from the viewpoint of controlling the purity in the cathode active material to improve battery characteristics, impurities such as Al are to be excluded. On the other hand, when recovering high-purity nickel, cobalt, and lithium for recycling waste electrodes and waste batteries, the cost for removing Al becomes a problem.

[0008] The present invention has been made to solve the above-described problems, and an object thereof is to provide a cathode active material for a lithium-ion battery, a cathode for a lithium-ion battery, a lithium-ion battery, a method for manufacturing a precursor of a cathode active material for a lithium-ion battery, and a method for manufacturing a cathode active material for a lithium-ion battery, which contain Al and exhibit good battery characteristics.

Means for Solving the Problems

[0009] The present invention completed based on the above findings is defined below. 1. Composition formula: Li a Ni (1-b-c-d) Co b Mn c Al d O 2 (In the above formula, 0.98 ≦ a ≦ 1.09, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, 0.0000003 ≦ d ≦ 0.007.) A cathode active material for a lithium-ion battery, which is represented by, has 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. The BET specific surface area is 0.20 to 0.80 m 2 / g, and the cathode active material for a lithium-ion battery according to 1 above. 3. A cathode for a lithium-ion battery, comprising the cathode active material for a lithium-ion battery according to 1 or 2 above. 4. A lithium-ion battery, comprising the cathode for a lithium-ion battery according to 3 above and an anode. 5. Using an aqueous solution containing (a) nickel salt, (b) cobalt salt, (c) manganese salt and (d) aluminum salt, and (e) a basic aqueous solution containing ammonia and / or a basic aqueous solution of an alkali metal as a reaction solution, and controlling the pH in the reaction solution to 10.0 to 11.5, the ammonium ion concentration to 7 to 20 g / L, and the liquid temperature to 59 to 61 °C, and including a step of performing a crystallization reaction while controlling. Composition formula: Ni (1-b-c-d) Co b Mn c Al d (OH) 2 (In the above formula, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, 0.0000003 ≦ d ≦ 0.007.) It is represented by, 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, and a method for producing a precursor of a cathode active material for a lithium-ion battery. 6. A precursor produced by the method for producing a precursor of a cathode active material for a lithium-ion battery according to 5 above and a lithium source, and the ratio of the sum of the number of atoms of metals consisting of Ni, Co and Mn (Me n ) to the number of atoms of lithium (Li n ), (Li n / Me n) is mixed so that it becomes 0.98 to 1.09 to form a lithium mixture; The step of firing the lithium mixture in an air or oxygen atmosphere at 450 to 750 ° C for 2 to 15 hours, and then firing at 700 to 900 ° C for 2 to 15 hours; A method for producing a positive electrode active material for a lithium ion battery, comprising:

Effect of the Invention

[0010] According to the present invention, 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, which exhibit good battery characteristics while containing Al.

Mode for Carrying Out the Invention

[0011] Next, modes 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 design changes, improvements, etc. may be appropriately 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 a lithium ion battery according to an embodiment of the present invention has a composition formula: Li a Ni (1-b-c-d) Co b Mn c Al d O 2 (In the above formula, 0.98 ≦ a ≦ 1.09, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, 0.0000003 ≦ d ≦ 0.007). The positive electrode active material is controlled such that a indicating the lithium composition in the composition formula is 0.98 ≦ a ≦ 1.09. Since a indicating the lithium composition is 0.98 or more, reduction of nickel due to lithium deficiency can be suppressed. Further, since a indicating the lithium composition is 1.09 or less, residual alkali components such as lithium carbonate and lithium hydroxide present on the surface of the positive electrode active material particles, which can be resistance components when used as a battery, can be suppressed.

[0013] The positive electrode active material for a lithium-ion battery according to an embodiment of the present invention has a nickel composition controlled to 1 - b - c - d (0.463 ≤ 1 - b - c - d ≤ 0.9199997) in the composition formula. Since the nickel composition is 0.463 or more, a good battery capacity of the lithium-ion battery can be obtained. Further, since the nickel composition is 0.9199997 or less, the crystal structure is stable, and the cycle characteristics can be improved by reducing the expansion and contraction behavior of the crystal lattice due to the insertion and desorption of lithium accompanying charge and discharge.

[0014] The positive electrode active material for a lithium-ion battery according to an embodiment of the present invention has a total of b representing the cobalt composition, c representing the manganese composition, and d representing the aluminum composition in the composition formula satisfying 0.0800003 ≤ b + c + d ≤ 0.537. Therefore, the cycle characteristics are improved, and the expansion and contraction behavior of the crystal lattice due to the insertion and desorption of lithium accompanying charge and discharge can be reduced. When the total of b representing the cobalt composition, c representing the manganese composition, and d representing the aluminum composition exceeds 0.537, the addition amounts of cobalt, manganese, and aluminum are too large, resulting in a large decrease in the initial discharge capacity, or there is a risk of being disadvantageous in terms of cost.

[0015] The cathode active material for a lithium-ion battery according to an embodiment of the present invention has an aluminum composition d controlled such that 0.0000003 ≤ d ≤ 0.007. Since the aluminum composition d is 0.0000003 or more, the cycle characteristics are improved, and it is possible to reduce the expansion and contraction behavior of the crystal lattice due to the insertion and extraction of lithium accompanying charge and discharge. When the aluminum composition d exceeds 0.007, the amount of aluminum added is too large and the decrease in the initial discharge capacity becomes significant. Thus, the cathode active material for a lithium-ion battery according to an embodiment of the present invention contains Al, yet the battery characteristics of the lithium-ion battery using it are good. Therefore, when recovering high-purity nickel, cobalt, and lithium as recycling of waste electrodes and waste batteries, it is possible to produce a lithium-ion battery having good battery characteristics using the cathode active material for a lithium-ion battery while suppressing the cost for removing Al.

[0016] The cathode active material for a lithium-ion battery according to an embodiment of the present invention mostly has a form of secondary particles in which a plurality of primary particles are aggregated, and may also be in a form that includes primary particles that are not aggregated as secondary particles partially. There are no particular limitations on the shape of the primary particles constituting the secondary particles and the primary particles existing alone, and they may have various shapes such as substantially spherical, substantially elliptical, substantially plate-shaped, substantially needle-shaped, etc. Also, there are no particular limitations on the form in which a plurality of primary particles are aggregated, and they may have various forms such as a form in which they aggregate in random directions, or a form in which they aggregate radially almost evenly from the central part 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% cumulative in the cumulative particle size distribution curve based on volume. When 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 and the energy density per volume decreases. When 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, and the coatability deteriorates when coating the positive electrode active material slurried on the current collector belt. 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. As the measurement method of the above 50% cumulative volume particle size D50, first, 100 mg of a sample (powder) of the positive electrode active material is irradiated with ultrasonic waves of 40 W for 60 seconds in a 50% flow rate using a laser diffraction type particle size distribution measuring device "MT3300EXII" manufactured by Microtrac, and after dispersion, the particle size distribution is measured to obtain a cumulative particle size distribution curve based on volume. Next, in the obtained cumulative particle size distribution curve, the volume particle size at 50% cumulative can be taken as the 50% cumulative volume particle size D50 of the powder of the positive electrode active material. In addition, the water-soluble solvent at the time of measurement can pass through a 0.02-μm filter, the solvent refractive index can be 1.333, the particle permeability condition can be transmission, the particle refractive index can be 1.81, the shape can be non-spherical, the measurement range can be 0.021 to 2000 μm, and the measurement time can be 30 seconds.

[0018] The cathode 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. When the tap density of the cathode active material is 2.0 g / cc or more, a battery with a high energy density per unit volume can be constructed. The tap density of the cathode active material is preferably 2.1 to 2.6 g / cc, and more preferably 2.3 to 2.4 g / cc. The tap density of the cathode active material is measured, for example, by putting 5 g of the cathode 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., performing 1500 taps with a stroke length of 55 mm, and then reading the scale of the graduated cylinder. Next, calculate "sample input amount (5 g) / reading value of the graduated cylinder scale (cc)", and use this as the tap density (g / cc).

[0019] The cathode active material for a lithium-ion battery according to an embodiment of the present invention has a c-axis lattice constant controlled to be 14.180 to 14.255 Å. When the c-axis lattice constant of the cathode active material is 14.180 Å or more, the crystal structure of the cathode active material for a lithium-ion battery can be stabilized and the insertion and extraction of Li can be ensured. When the c-axis lattice constant of the cathode active material exceeds 14.255 Å, the crystal lattice is distorted, and the charge-discharge capacity of the lithium-ion battery may deteriorate due to the influence of the decrease in the mobility of Li and the resulting decrease in load characteristics. The c-axis lattice constant of the cathode active material is preferably 14.183 to 14.252 Å. The c-axis lattice constant of the cathode active material can be measured, for example, using the following XRD diffractometer under the following conditions. ·XRD diffractometer: SmartLab (manufactured by Rigaku Corporation) ·X-ray source: CuKα (λ = 1.5406 Å) ·Apply the sample (cathode active material) 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 can be calculated using the analysis software "Rigaku Corporation, PDXL" from the peaks derived from a total of nine crystal planes of (003), (101), (012), (104), (015), (107), (018), (110), and (113) in the XRD diffraction pattern measured under the above conditions.

[0020] The cathode active material for a lithium-ion battery according to an embodiment of the present invention preferably has a BET specific surface area of 0.20 to 0.80 m 2 / g. When the BET specific surface area is 0.20 m 2 / g or more, the contact area of the cathode active material becomes large, and the conductivity of Li ions becomes good. For this reason, it becomes possible to manufacture a high-capacity lithium-ion battery. Further, when the BET specific surface area exceeds 0.80 m 2 / g, the precipitation reaction of lithium ions from the residual alkali in the cathode active material is promoted during repeated charge and discharge. The precipitated lithium compound becomes the internal resistance of the battery and reduces the charge and discharge capacity. The BET specific surface area is more preferably 0.3 to 0.70 m 2 / g. The BET specific surface area can be measured by the following method. That is, first, 1.0 g of the cathode active material (powder) is weighed into a glass cell, set in a degassing device, filled with nitrogen gas in the glass cell, and then heat-treated at 40 °C for 20 minutes in a nitrogen gas atmosphere to degas. Then, the glass cell containing the degassed sample (powder) is set in a specific surface area measuring device "Monosorb Model MS-21" manufactured by Quantachrome Corporation, and while flowing a mixed gas of He: 70 at% - N 2 : 30 at% as the adsorption gas, the specific surface area X is measured by the BET method (one-point method).

[0021] (Method for manufacturing a precursor of a cathode active material for a lithium-ion battery) Next, the method for manufacturing a precursor of a cathode active material for a lithium-ion battery according to an embodiment of the present invention will be described in detail. The precursor of the cathode active material for a lithium-ion battery according to an embodiment of the present invention has a composition formula: Ni (1-b-c-d) Cob Mn c Al d (OH) 2 (In the above formula, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, and 0.0000003 ≦ d ≦ 0.007.) It is represented by, 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. The 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 prepares an aqueous solution containing (a) a nickel salt, (b) a cobalt salt, (c) a manganese salt, and (d) an aluminum salt, and (e) a basic aqueous solution containing ammonia and / or a basic aqueous solution of an alkali metal. Examples of (a) the nickel salt include nickel sulfate, nickel nitrate, and nickel chloride. Examples of (b) the cobalt salt include cobalt sulfate, cobalt nitrate, and cobalt chloride. Examples of (c) the manganese salt include manganese sulfate, manganese nitrate, and manganese chloride. Examples of (d) the aluminum salt include aluminum sulfate, sodium aluminate, aluminum nitrate, and aluminum chloride. Note that the aluminum salt may be added as a raw material or may be mixed as an impurity. Examples of (e) the basic aqueous solution containing ammonia include aqueous ammonia, aqueous ammonium sulfate, aqueous ammonium carbonate, and aqueous ammonium chloride. The basic aqueous solution of an alkali metal may be an aqueous solution of sodium hydroxide, potassium hydroxide, a carbonate, or the like. Examples of the aqueous solution of the carbonate include aqueous solutions using salts of a carbonate group such as aqueous sodium carbonate, aqueous potassium carbonate, aqueous sodium hydrogen carbonate, and aqueous potassium hydrogen carbonate.

[0022] Also, the composition of the aqueous solution can be appropriately adjusted according to the composition of the precursor to be produced, but it is preferably an aqueous solution containing (a) nickel ions at 30 to 150 g / L, (b) cobalt ions at 3 to 25 g / L, (c) manganese ions at 1 to 32 g / L, (d) aluminum ions at 0.001 to 0.2 g / L, (e) a basic aqueous solution containing ammonia at 7 to 28% by mass and / or a basic aqueous solution with an alkali metal concentration of 10 to 30% by mass.

[0023] Next, an aqueous solution containing the above-mentioned (a) nickel salt, (b) cobalt salt, (c) manganese salt, and (d) aluminum salt, and (e) a basic aqueous solution containing ammonia and / or a basic aqueous solution of an alkali metal is used as a reaction solution, and a crystallization reaction is carried out while controlling the pH in the reaction solution to 10.0 to 11.5, the ammonium ion concentration to 7 to 20 g / L, and the liquid temperature to 59 to 61°C. At this time, chemicals may be fed from three tanks: a tank containing a mixed aqueous solution of nickel salt, cobalt salt, manganese salt, and aluminum salt, a tank containing a basic aqueous solution containing ammonia, and a tank containing a basic aqueous solution of an alkali metal, into the reaction tank. By carrying out the crystallization reaction while controlling the pH in the reaction solution during the coprecipitation reaction to 10.0 to 11.5, the ammonium ion concentration to 7 to 20 g / L, and the liquid temperature to 59 to 61°C, the metal solubility in the reaction solution can be controlled, and particles with uniformly dispersed aluminum can be produced, and a precursor of a positive electrode active material according to an embodiment of the present invention with good discharge characteristics can be produced. Also, by optimizing the reaction conditions of the metal hydroxide, which is the precursor as described above, the adhesion of impurities to the surface of the positive electrode active material obtained after firing is preferably suppressed, so that washing is not required. Furthermore, a chelating material and a metal oxide coat during the coprecipitation reaction are not required. As a result, the production efficiency is improved.

[0024] (Method for Producing Positive Electrode Active Material for Lithium-Ion Battery) Next, the manufacturing method of the positive electrode active material for a lithium ion battery according to an embodiment of the present invention will be described in detail. The manufacturing method of the positive electrode active material for a lithium ion battery according to an embodiment of the present invention first adds a lithium source 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, with the ratio of the sum of the atomic numbers of the metals consisting of Ni, Co, and Mn (Me n ) to the atomic number of lithium (Li n ) (Li n / Me n ) being 0.98 to 1.09, to form a lithium mixture. Examples of the lithium source include lithium carbonate and lithium hydroxide. As the 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, a V-type mixer, or the like.

[0025] Next, the lithium mixture is fired in an air atmosphere, preferably in an oxygen atmosphere, at 450 to 750 °C for 2 to 15 hours in an air or oxygen atmosphere, and then further fired at 700 to 900 °C for 2 to 15 hours. Thereafter, if necessary, the fired body can be pulverized 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 a lithium ion battery according to an embodiment of the present invention has a structure in which, for example, a positive electrode mixture prepared by mixing the positive electrode active material for a lithium ion battery having the above-described configuration, a conductive auxiliary material, and a binder is provided on one or both sides of a current collector. Further, the lithium ion battery according to an embodiment of the present invention includes a positive electrode for a lithium ion battery having such a configuration and a known negative electrode for a lithium ion battery.

[0027] Examples of the conductive additive include metal-based conductive additives (such as aluminum, stainless steel (SUS), silver, gold, copper, and titanium), carbon-based conductive additives (such as graphite and carbon black (acetylene black, ketjen black, furnace black, channel black, and thermal lamp black)), 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 thereof. Among them, from the viewpoint of electrical stability, aluminum, stainless steel, silver, gold, copper, titanium, carbon-based conductive additives, and mixtures thereof are more preferable, silver, gold, aluminum, stainless steel, and carbon-based conductive additives are further preferable, and carbon-based conductive additives are particularly preferable. In addition, as these conductive additives, those obtained by coating a conductive material (preferably a metal one among the above-mentioned conductive additives) around a particulate ceramic material or resin material by plating or the like may also be used. The shape (form) of the conductive additive is not limited to the particulate form and may be a form other than the particulate form, and may be a form that has been put into practical use as a so-called filler-based conductive additive such as carbon nanofibers and carbon nanotubes.

[0028] Examples of the binder include substances generally used for positive electrode binders for lithium-ion batteries, and 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 preferable. Specifically, PVDF-HFP, PVDF-HFP-TEF, PVDF-TEF, TEF-HFP, etc. are mentioned.

[0029] The positive electrode binder 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 binder slurry, applying the slurry to one or both sides of a current collector, and then subjecting it to drying or the like to be provided on the current collector to form a positive electrode active material layer.

[0030] As the solvent for the positive electrode active material slurry, known organic solvents such as hydrocarbon-based organic solvents, amide compounds, lactam compounds, urea compounds, organic sulfur compounds, cyclic organic phosphorus compounds, etc. can be used as a single solvent or as a mixed solvent. As the 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, cyclohexane, etc. Examples of unsaturated hydrocarbons include hexene, heptene, cyclohexene, etc. Examples of aromatic hydrocarbons include toluene, xylene, decalin, 1,2,3,4-tetrahydronaphthalene, etc. Among these, toluene and xylene are particularly preferred.

[0031] Examples of the material constituting the current collector include metal materials such as copper, aluminum, titanium, stainless steel, nickel and their alloys, as well as fired carbon, conductive polymer materials, conductive glass, etc. Among them, from the viewpoints of weight reduction, corrosion resistance and high conductivity, aluminum is more preferred. Also, 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 it may be a sheet-like current collector made of the above materials or a deposited layer composed of fine particles made of the above materials. The thickness of the current collector is not particularly limited, but is preferably 1 to 30 μm. As the conductive polymer material constituting the resin current collector, for example, a conductive polymer or a resin to which a conductive agent is added as necessary can be used.

[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] A lithium-ion battery using a positive electrode for a lithium-ion battery is obtained by combining a negative electrode as a counter electrode, housing it together with a separator in a cell container, injecting an electrolytic solution, and sealing the cell container. Alternatively, a bipolar electrode can be produced by forming a positive electrode on one surface of a current collector and a negative electrode on the other surface, laminating the bipolar electrode with a separator, housing it in a cell container, injecting an electrolytic solution, and sealing the cell container.

[0034] Examples of the negative electrode include those containing a negative electrode active material, a conductive auxiliary material, a current collector, and the like. As the negative electrode active material, known negative electrode active materials for lithium-ion batteries can be used, such as carbon-based materials (graphite, non-graphitizable carbon, amorphous carbon, resin fired bodies (such as those obtained by firing and carbonizing phenol resins and furan resins, etc.), cokes (such as pitch coke, needle coke, and petroleum coke, etc.), and carbon fibers, etc.), silicon-based materials (silicon, silicon oxide (SiO x ), silicon-carbon composites (those obtained by coating the surface of carbon particles with silicon and / or silicon carbide, those obtained by coating the surface of silicon particles or silicon oxide particles with carbon and / or silicon carbide, and silicon carbide, etc.), and silicon alloys (such as 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.), etc.), conductive polymers (such as polyacetylene and polypyrrole, etc.), metals (such as tin, aluminum, zirconium, and titanium, etc.), metal oxides (such as titanium oxides and lithium-titanium oxides, etc.), and metal alloys (such as lithium-tin alloys, lithium-aluminum alloys, and lithium-aluminum-manganese alloys, etc.), etc., and mixtures of these with carbon-based materials, etc. Also, as the conductive auxiliary material, the same conductive auxiliary materials as those described above for the positive electrode can be preferably used.

[0035] Examples of the current collector include the same ones as those constituting the current collector of the positive electrode described above. From the viewpoints of weight reduction, corrosion resistance, and high conductivity, copper is preferably used. Also, a resin current collector may be used, and the same ones as those constituting the current collector of the positive electrode described above can be preferably 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 a porous film made of polyethylene or polypropylene, a laminated film of a porous polyethylene film and porous polypropylene, a nonwoven fabric made of synthetic fibers (such as polyester fibers and aramid fibers) or glass fibers, and those with ceramic fine particles such as silica, alumina, and titania adhered to their surfaces.

Examples

[0037] Examples are provided below to better understand the present invention and its advantages, but the present invention is not limited to these examples.

[0038] (Example 1) First, nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts so that Ni:Co:Mn = 50:20:30, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was less than 0.001 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank 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 of the reaction tank was 1000 rpm, and heat was maintained with a water jacket so that the liquid temperature of the reaction tank was kept at 60°C. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only the above-mentioned nitrogen gas but also any gas that does not promote oxidation, such as helium, neon, argon, and carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120°C for 12 hours using a box-type dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the number of atoms of the metals Ni, Co, and Mn in the precursor of the positive electrode active material is defined as Me, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms was 1.06, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina crucible and fired in a muffle furnace at 750 °C for 2 hours in an air atmosphere, then heated to 900 °C and held at this temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0039] (Example 2) First, a predetermined amount of nickel sulfate, cobalt sulfate, and manganese sulfate were weighed so that Ni:Co:Mn = 50:20:30, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was less than 0.001 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20 mass% aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank 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 of the reaction tank was 1000 rpm, and it was kept warm with a water jacket so that the liquid temperature of the reaction tank was maintained at 60 °C. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only for the above-mentioned nitrogen gas but also for any gas that does not promote oxidation, such as helium, neon, argon, and carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the atomic numbers of the metals Ni, Co, and Mn in the precursor of the positive electrode active material is defined as Me, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms was 1.09, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina crucible and fired in a muffle furnace at 750 °C for 2 hours in an air atmosphere, then heated to 900 °C and held at this temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0040] (Example 3) First, a predetermined amount of nickel sulfate, cobalt sulfate, and manganese sulfate were weighed so that Ni:Co:Mn = 50:20:30, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was less than 0.001 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank 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 tank was 1000 rpm, and it was kept warm with a water jacket so that the liquid temperature in the reaction tank was maintained at 60 °C. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only limited to the above nitrogen gas as long as it is a gas that does not promote oxidation such as helium, neon, argon, or carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the atomic numbers of the metals consisting of Ni, Co, and Mn in the precursor of the positive electrode active material is defined as Me, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms became 1.06, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina mortar and fired in a muffle furnace at 750 °C for 2 hours in an air atmosphere, then heated to 880 °C and held at this temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0041] (Example 4) First, a predetermined amount of nickel sulfate, cobalt sulfate, and manganese sulfate were weighed so that Ni:Co:Mn = 50:20:30, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was less than 0.001 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank became 10.1 and the ammonium ion concentration became 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 of the reaction tank was 1000 rpm, and it was kept warm with a water jacket so that the liquid temperature of the reaction tank was maintained at 60 °C. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only limited to the above nitrogen gas as long as it is a gas that does not promote oxidation such as helium, neon, argon, and carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the atomic numbers of the metals consisting of Ni, Co, and Mn in the precursor of the positive electrode active material is defined as Me, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms became 1.06, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina mortar and fired in a muffle furnace at 750 °C for 2 hours in an air atmosphere, then heated to 900 °C and held at this temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0042] (Example 5) First, a predetermined amount of nickel sulfate, cobalt sulfate, and manganese sulfate were weighed so that Ni:Co:Mn = 50:20:30, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was less than 0.001 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank became 10.2 and the ammonium ion concentration became 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 of the reaction tank was 1000 rpm, and it was kept warm with a water jacket so that the liquid temperature of the reaction tank was maintained at 60 °C. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only limited to the above nitrogen gas as long as it is a gas that does not promote oxidation such as helium, neon, argon, and carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the atomic numbers of the metals Ni, Co, and Mn in the precursor of the positive electrode active material is defined as Me, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms was 1.06, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina mortar and fired in a muffle furnace at 750 °C for 2 hours in an air atmosphere, then heated to 880 °C and held at this temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0043] (Example 6) First, a predetermined amount of nickel sulfate, cobalt sulfate, and manganese sulfate were weighed so that Ni:Co:Mn = 49.5:20.1:30.3, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was 0.046 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank was 10.2 and the ammonium ion concentration was 9.9 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 of the reaction tank was 1000 rpm, and the temperature of the liquid in the reaction tank was maintained at 60 °C using a water jacket for heat preservation. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank is not limited to the above nitrogen gas and can be used as long as it is a gas that does not promote oxidation, such as helium, neon, argon, carbon dioxide gas, etc. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. 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 defined as Me, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms became 1.06, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina crucible and fired in a muffle furnace at 750 °C for 2 hours in an air atmosphere, then heated up to 880 °C and held at this temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0044] (Example 7) First, nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts so that Ni:Co:Mn = 49.3:20.3:30.2, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was 0.06 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20 mass% aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank became 10.2 and the ammonium ion concentration became 11.1 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 of the reaction tank was 1000 rpm, and it was kept warm with a water jacket so that the liquid temperature of the reaction tank was maintained at 60 °C. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only limited to the above nitrogen gas as long as it is a gas that does not promote oxidation such as helium, neon, argon, and carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the atomic numbers of the metals consisting of Ni, Co, and Mn in the precursor of the positive electrode active material is defined as Me, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms was 1.06, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina mortar and fired in a muffle furnace at 750 °C for 2 hours in an air atmosphere, then heated up to 880 °C and held at this temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0045] (Example 8) First, a predetermined amount of nickel sulfate, cobalt sulfate, and manganese sulfate were weighed so that Ni:Co:Mn = 49.0:20.4:30.0, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was 0.19 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20 mass% aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank 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 of the reaction tank was 1000 rpm, and it was kept warm with a water jacket so that the liquid temperature of the reaction tank was maintained at 60 °C. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only limited to the above nitrogen gas as long as it is a gas that does not promote oxidation such as helium, neon, argon, and carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. 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 defined as Me, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms was 1.06, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina crucible and fired in a muffle furnace at 750 °C for 2 hours in an air atmosphere, then heated up to 880 °C and held at this temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0046] (Example 9) First, a predetermined amount of nickel sulfate, cobalt sulfate, and manganese sulfate were weighed so that Ni:Co:Mn = 50:20:30, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was less than 0.001 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20 mass% aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank 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 of the reaction tank was 1000 rpm, and the temperature of the liquid in the reaction tank was maintained at 60 °C by a water jacket. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only limited to the above nitrogen gas as long as it is a gas that does not promote oxidation such as helium, neon, argon, and carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the number of atoms of the metals Ni, Co, and Mn in the precursor of the positive electrode active material is defined as Me, lithium carbonate and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms was 1.06, and they were mixed in a planetary ball mill for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina crucible and fired in a muffle furnace at 750 °C for 2 hours in an air atmosphere, then heated up to 880 °C and held at this temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0047] (Example 10) First, a predetermined amount of nickel sulfate, cobalt sulfate, and manganese sulfate were weighed so that Ni:Co:Mn = 82:15:3, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was less than 0.001 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank 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 of the reaction tank was 1000 rpm, and the temperature of the liquid in the reaction tank was maintained at 60 °C by a water jacket. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only limited to the above nitrogen gas as long as it is a gas that does not promote oxidation such as helium, neon, argon, carbon dioxide gas, etc. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the number of atoms of the metals consisting of Ni, Co, and Mn in the precursor of the positive electrode active material is defined as Me, lithium hydroxide and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms became 1.01, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina mortar and fired in a muffle furnace at 500 °C for 8 hours in an oxygen atmosphere, then heated up to 740 °C and held at that temperature for 4 hours to perform firing, thereby obtaining a positive electrode active material.

[0048] (Example 11) First, a predetermined amount of nickel sulfate, cobalt sulfate, and manganese sulfate were weighed so that Ni:Co:Mn = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was less than 0.001 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank became 11.0 and the ammonium ion concentration became 7.2 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 of the reaction tank was 820 rpm, and it was kept warm with a water jacket so that the liquid temperature of the reaction tank was maintained at 60 °C. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only limited to the above nitrogen gas as long as it is a gas that does not promote oxidation such as helium, neon, argon, or carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the atomic numbers of the metals consisting of Ni, Co, and Mn in the precursor of the positive electrode active material was defined as Me, lithium hydroxide and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms became 1.01, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina mortar and fired in a muffle furnace at 500 °C for 8 hours in an oxygen atmosphere, then heated up to 720 °C and held at this temperature for 4 hours to perform firing, thereby obtaining a positive electrode active material.

[0049] (Example 12) First, nickel sulfate, cobalt sulfate, and manganese sulfate were weighed in predetermined amounts so that Ni:Co:Mn = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. The Al concentration of this mixed metal salt solution was less than 0.001 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into a reaction tank equipped with a stirring blade so that the pH in the reaction tank became 11.0 and the ammonium ion concentration became 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 of the reaction tank was 820 rpm, and it was kept warm with a water jacket so that the liquid temperature of the reaction tank was maintained at 60 °C. In addition, nitrogen gas was introduced into the reaction tank to prevent oxidation of the coprecipitate generated in the crystallization reaction. The gas introduced into the reaction tank can be used not only limited to the above nitrogen gas as long as it is a gas that does not promote oxidation such as helium, neon, argon, and carbon dioxide gas. Next, the obtained precipitate was suction filtered, washed with water, and dried at 120 °C for 12 hours using a box dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the number of atoms of the metals Ni, Co, and Mn in the precursor of the positive electrode active material was defined as Me, lithium hydroxide and the precursor of the positive electrode active material were mixed so that the ratio (Li / Me) with the number of lithium (Li) atoms became 0.98, and they were mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina crucible and fired in a muffle furnace at 500 °C for 8 hours in an oxygen atmosphere, then heated up to 720 °C and held at that temperature for 4 hours to perform firing, thereby obtaining a positive electrode active material.

[0050] (Composition) Regarding the powders of the precursors and positive electrode active materials of Examples 1 to 12, the compositions were measured as follows. Regarding the nickel, cobalt, and manganese compositions, each obtained precursor and a sample (powder) of each positive electrode active material were weighed in a specified amount, decomposed by an alkali fusion method, and then subjected to composition analysis using an inductively coupled plasma optical emission spectrometer (ICP-OES) "PS7800" manufactured by Hitachi High-Tech Corporation. Regarding the aluminum compositions of the precursors and positive electrode active materials, each obtained precursor and a sample (powder) of each positive electrode active material were weighed in a specified amount, solubilized by acid decomposition, and then subjected to composition analysis using an ICP mass spectrometer (ICP-MS) "SPQ9700" manufactured by SII NanoTechnology Inc.

[0051] (Average particle size D50) Regarding the powders of the precursors and positive electrode active materials of Examples 1 to 12, the average particle size D50 was measured as follows. For each of the obtained precursors and 100 mg of the sample (powder) of each cathode active material, using a laser diffraction particle size distribution analyzer "MT3300EXII" manufactured by Microtrac, ultrasonic waves of 40 W were irradiated for 60 seconds in a 50% flow rate for dispersion, and then 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 volume particle size at 50% cumulative was defined as the 50% cumulative volume particle size D50 (average particle size D50) of the powder of the cathode active material. In addition, the water-soluble solvent during measurement was passed through a 0.02 μm filter, the solvent refractive index was 1.333, the particle permeability condition was transmission, the particle refractive index was 1.81, the shape was non-spherical, the measurement range was 0.021 to 2000 μm, and the measurement time was 30 seconds.

[0052] (Tap density) For the powders of the precursors and cathode active materials of Examples 1 to 12, the tap density was measured as follows. 5 g of each of the obtained precursors and the sample (powder) of each cathode active material were put into a 10 cc graduated cylinder, placed in a powder density measuring instrument "KYT-4000K" manufactured by Seishin Enterprise Co., Ltd., and tapped 1500 times with a stroke length of 55 mm. Then, the scale reading of the graduated cylinder was read. Next, "sample input amount (5 g) / scale reading value of the graduated cylinder (cc)" was calculated, and this was taken as the tap density (g / cc).

[0053] (BET specific surface area) For the powders of the precursors and cathode active materials of Examples 1 to 12, the BET specific surface area was measured as follows. 1.0 g of each of the obtained precursors and the sample (powder) of each cathode active material were weighed into a glass cell, set in a degassing device, filled with nitrogen gas in the glass cell, and then heat-treated at 40 °C for 20 minutes in a nitrogen gas atmosphere and degassed. Then, the glass cell containing the degassed sample (powder) was set in a specific surface area measuring instrument "Monosorb Model MS-21" manufactured by Quantachrome, and while flowing a mixed gas of He: 70 at% - N 2 : 30 at% as the adsorption gas, the specific surface area X was measured by the BET method (one-point method).

[0054] (c-axis lattice constant) Regarding the powders of the cathode active materials of Examples 1 to 12, the c-axis lattice constants were measured as follows respectively. The following XRD diffractometer and conditions were used. ·XRD diffractometer: SmartLab (manufactured by Rigaku Corporation) ·X-ray source: CuKα (λ = 1.5406 Å) ·Apply the sample (cathode active material) 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 the analysis software "Rigaku Corporation, PDXL" from the peaks derived from a total of 9 crystal planes of (003), (101), (012), (104), (015), (107), (018), (110), and (113) in the XRD diffraction pattern measured under the above conditions.

[0055] (Discharge capacity) Regarding the powders of the cathode active materials of Examples 1 to 12, the discharge capacities were measured as follows respectively. The obtained cathode active material, conductive material (acetylene black), and binder (polyvinylidene fluoride) were weighed at a ratio of 90:5:5. The binder was dissolved in an organic solvent (N-methylpyrrolidone), and the cathode material and conductive material were mixed to form a slurry, which was coated on an Al foil, dried, and pressed to obtain a cathode. Subsequently, a 2032-type coin cell for evaluation with Li as the counter electrode was fabricated, and the initial battery characteristics at 25°C (charge capacity, discharge capacity, charge-discharge characteristics) were measured using a solution in which 1 M-LiPF6 was dissolved in EC-DMC (3:7) as the electrolyte. The charge-discharge conditions were as follows: charge condition: CC / CV 4.3 V, 0.1C; discharge condition: CC 0.05C, up to 3.0V. The manufacturing conditions and evaluation results of Examples 1 to 12 described above are shown in Tables 1 and 2.

[0056] [Table 1]

[0057] [Table 2]

[0058] (Evaluation results) The cathode active materials of Examples 1 to 12 all had the following compositional formula. In Tables 1 and 2, the "Li / Me ratio" indicates the compositional ratio of Li to the total of Ni, Co, and Mn in the cathode active material. Compositional formula: Li a Ni (1-b-c-d) Co b Mn c Al d O 2 (In the above formula, 0.98 ≦ a ≦ 1.09, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, 0.0000003 ≦ d ≦ 0.007.) Also, the cathode active materials of Examples 1 to 12 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, satisfied a c-axis lattice constant of 14.180 to 14.255 Å, and had good battery characteristics (discharge capacity).

Claims

1. Composition formula: Li a Ni (1-b-c-d) Co b Mn c Al d O 2 (In the above formula, 0.98 ≦ a ≦ 1.09, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, 0.0000003 ≦ d ≦ 0.007.) A positive electrode active material for a lithium-ion battery, which is represented by the formula, has 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. The BET specific surface area is 0.20 to 0.80 m 2 / g, and the positive electrode active material for a lithium ion battery according to claim 1.

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. (a) An aqueous solution containing a nickel salt, (b) a cobalt salt, (c) a manganese salt, and (d) an aluminum salt, and (e) a basic aqueous solution containing ammonia and / or a basic aqueous solution of an alkali metal, are used as a reaction solution, and a crystallization reaction is carried out while controlling the pH in the reaction solution to 10.0 to 11.5, the ammonium ion concentration to 7 to 20 g / L, and the liquid temperature to 59 to 61 °C. Composition formula: Ni (1-b-c-d) Co b Mn c Al d (OH) 2 (In the above formula, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, 0.0000003 ≦ d ≦ 0.007.) represented by, 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, a method for producing a precursor of a positive electrode active material for a lithium ion battery.

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

Images