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)CobMncCadO2 (where 0.98≤a≤1.09, 0.06≤b≤0.21, 0.02≤c≤0.32, and 0.000002≤d≤0.0007), 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 positive electrode active materials for non-aqueous electrolyte secondary batteries, 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 is known as a metal with limited production countries and 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 a lithium-ion secondary battery 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 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 contain various metals in the can body and flame retardant materials for fire prevention. To recover high-purity nickel, cobalt, and lithium, a large amount of purification cost is required, resulting in a high production cost of the cathode active material. In particular, regarding calcium (Ca), purification extraction is difficult and a corresponding recycling cost must be incurred to completely remove it.

[0007] Thus, from the perspective of controlling the purity in the cathode active material to improve battery characteristics, it is desirable to exclude impurities such as Ca. On the other hand, when recovering high-purity nickel, cobalt, and lithium for recycling waste electrodes and waste batteries, the cost for removing Ca becomes a problem.

[0008] The present invention has been made to solve the above 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 Ca and exhibit good battery characteristics.

Means for Solving the Problems

[0009] The present invention completed based on the above findings is defined as follows. 1. Composition formula: Li a Ni (1-b-c-d) Co b Mn c Ca d O 2 (In the above formula, 0.98 ≦ a ≦ 1.09, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, 0.000002 ≦ d ≦ 0.0007.) A positive electrode active material for a lithium ion battery, represented by [formula], having a 50% cumulative volume particle size D50 of 3.0 to 11.0 μm, a tap density of 2.0 to 2.6 g / cc, and a c-axis lattice constant of 14.180 to 14.255 Å. 2. The positive electrode active material for a lithium ion battery according to 1 above, having a BET specific surface area of 0.20 to 0.80 m 2 / g. 3. A positive electrode for a lithium ion battery, comprising the positive electrode active material for a lithium ion battery according to 1 or 2 above. 4. A lithium ion battery, comprising the positive electrode for a lithium ion battery according to 3 above and a negative electrode. 5. A step of performing a crystallization reaction 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, using an aqueous solution containing (a) a nickel salt, (b) a cobalt salt, (c) a manganese salt, and (d) a calcium salt, and an aqueous basic solution containing (e) ammonia and / or an aqueous basic solution of an alkali metal as a reaction solution. Composition formula: Ni (1-b-c-d) Co b Mn c Ca d (OH) 2 (In the above formula, 0.06 ≤ b ≤ 0.21, 0.02 ≤ c ≤ 0.32, 0.00001 ≤ d ≤ 0.0007.) A method for producing a precursor of a positive electrode active material for a lithium ion battery, represented by [formula], having 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. 6. A step of mixing a precursor produced by the method for producing a precursor of a positive electrode active material for a lithium ion battery according to 5 above and a lithium source so that the ratio (Li n ) 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 / Me n ) is 0.98 to 1.09 to form a lithium mixture. The 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 producing a positive electrode active material for a lithium ion battery, comprising:

Advantages 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 contain Ca and exhibit good battery characteristics.

Embodiments for Carrying Out the Invention

[0011] Next, embodiments for carrying out the present invention will be described in detail. It should be understood that the present invention is not limited to the following embodiments, and that design changes, improvements, etc. can 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 Ca d O 2 (In the above formula, 0.98 ≦ a ≦ 1.09, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, 0.000002 ≦ d ≦ 0.0007). The positive electrode active material has a lithium composition a in the composition formula controlled to 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 (0.4693 ≤ 1-b-c-d ≤ 0.919998) in the composition formula. Since the nickel composition is 0.4693 or more, a good battery capacity of the lithium-ion battery can be obtained. Further, since the nickel composition is 0.919998 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 calcium composition in the composition formula satisfying 0.080002 ≤ b + c + d ≤ 0.5307. 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. If the total of the cobalt composition, manganese composition, and calcium composition exceeds 0.5307, the addition amounts of cobalt, manganese, and calcium are too large, resulting in a large decrease in the initial discharge capacity, or it may be disadvantageous in terms of cost.

[0015] The positive electrode active material for a lithium-ion battery according to an embodiment of the present invention has d representing the calcium composition controlled to 0.000002 ≤ d ≤ 0.0007. Since d representing the calcium composition is 0.000002 or more, 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. If d representing the calcium composition exceeds 0.0007, the addition amount of calcium is too large, resulting in a large decrease in the initial discharge capacity. Thus, the positive electrode active material for a lithium-ion battery according to an embodiment of the present invention contains Ca, 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, a lithium-ion battery having good battery characteristics can be manufactured while suppressing the cost for removing Ca using the positive electrode active material for the lithium-ion battery.

[0016] The positive electrode 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 have a form in which primary particles that are not aggregated as secondary particles are partially included. The shape of the primary particles constituting the secondary particles and the primary particles existing alone is not particularly limited, and may be various shapes such as substantially spherical, substantially elliptical, substantially plate-shaped, and substantially needle-shaped. Further, the form in which a plurality of primary particles are aggregated is not particularly limited, and may be various forms such as a form in which they are aggregated in random directions or a form in which they are aggregated substantially evenly radially from the central portion 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 band. 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, more preferably 2.3 to 2.6 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, installing 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 take this as the tap density (g / cc).

[0019] The c-axis lattice constant of the cathode active material for a lithium-ion battery according to an embodiment of the present invention is 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, there is a risk that the charge-discharge capacity of the lithium-ion battery will deteriorate due to the distortion of the crystal lattice and the influence of the decrease in the mobility of Li resulting in a decrease in load characteristics. The c-axis lattice constant of the cathode active material is preferably 14.183 to 14.248 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) ·Coat the sample (cathode active material) on 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. Therefore, it becomes possible to manufacture a high-capacity lithium-ion battery. Also, 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] (Manufacturing method of the precursor of the cathode active material for a lithium-ion battery) Next, the manufacturing method of the precursor of the 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 Ca d (OH) 2 (In the above formula, 0.06 ≦ b ≦ 0.21, 0.02 ≦ c ≦ 0.32, 0.00001 ≦ d ≦ 0.0007.) 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) a calcium 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 calcium salt include calcium sulfate, calcium nitrate, and calcium chloride. The calcium 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, etc. 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] In addition, 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) 30 to 150 g / L of nickel ions, (b) an aqueous solution containing 3 to 25 g / L of cobalt ions, (c) an aqueous solution containing 1 to 32 g / L of manganese ions, (d) an aqueous solution containing 0.003 to 0.06 g / L of calcium ions, (e) a basic aqueous solution containing 7 to 28% by mass of ammonia and / or a basic aqueous solution having 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) calcium 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, the chemical solution may be fed from three tanks, namely, a tank containing a mixed aqueous solution of nickel salt, cobalt salt, manganese salt, and calcium 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 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 during the coprecipitation reaction, the metal solubility in the reaction solution can be controlled, particles with uniformly dispersed calcium can be produced, and a precursor of the positive electrode active material according to an embodiment of the present invention having good discharge characteristics can be produced. Further, 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 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, and the sum of the atomic numbers of the metals consisting of Ni, Co, and Mn (Me n ) and the atomic number of lithium (Li n ) in a ratio (Li n / Me n ) of 0.98 to 1.09 are mixed 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 calcined 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 calcined 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 included.

[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, coating one or both sides of a current collector, and then drying or the like to provide it 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 alone 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 fabricated by forming a positive electrode on one surface of a current collector and a negative electrode on the other surface, stacking 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, etc. 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 with the surface of carbon particles coated with silicon and / or silicon carbide, those with the surface of silicon particles or silicon oxide particles coated with carbon and / or silicon carbide, and silicon carbide, etc.), and silicon alloys (such as silicon-aluminum alloy, silicon-lithium alloy, silicon-nickel alloy, silicon-iron alloy, silicon-titanium alloy, silicon-manganese alloy, silicon-copper alloy, and silicon-tin alloy, 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 alloy, lithium-aluminum alloy, and lithium-aluminum-manganese alloy, etc.), etc., and mixtures of these with carbon-based materials, etc. Also, as the conductive auxiliary material, the same conductive auxiliary materials as those for the positive electrode described above 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 Ca concentration of this mixed metal salt solution was 0.006 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 10.6 and the ammonium ion concentration became 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 retained 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 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, 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 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 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 Ca concentration of this mixed metal salt solution was 0.007 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 10.4 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 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 1.09, 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 that 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 Ca concentration of this mixed metal salt solution was 0.007 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 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 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, 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 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 880 °C and held at that 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 Ca concentration of this mixed metal salt solution was 0.006 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20% by mass sodium hydroxide aqueous 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 heat was retained 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 the above 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 dryer. Thereby, a precursor of the positive electrode active material was produced. Next, when the sum of the atomic numbers of the metals composed of Ni, Co, and Mn of the precursor of the positive electrode active material was 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 mixed in an automatic mortar for 30 minutes to obtain a mixed powder. Next, the mixed powder was filled into an alumina crucible, fired in a muffle furnace at 750°C for 2 hours in an air atmosphere, heated to 900°C, and held at this temperature for 8 hours to perform firing to obtain 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 Ca concentration of this mixed metal salt solution was 0.006 g / L. Next, a mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into the 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 heat was retained 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 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, 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 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 to 880°C and held at that temperature for 8 hours to perform firing, and a positive electrode active material was obtained.

[0043] (Example 6) 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 Ca concentration of this mixed metal salt solution was 0.055 g / L. Next, a mixed metal salt solution, aqueous ammonia, and a 20% by mass aqueous sodium hydroxide solution were fed into the reaction tank equipped with a stirring blade so that the pH in the reaction tank became 10.2 and the ammonium ion concentration became 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 heat was retained 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 vessel to prevent oxidation of the coprecipitate produced in the crystallization reaction. The gas introduced into the reaction vessel can be used not only the above 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 dryer. Thus, 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 was 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 that temperature for 8 hours to perform firing, thereby obtaining a positive electrode active material.

[0044] (Example 7) First, predetermined amounts 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 Ca concentration of this mixed metal salt solution was 0.007 g / L. Next, the mixed metal salt solution, aqueous ammonia, and a 20 mass% aqueous sodium hydroxide solution were fed into a reaction vessel equipped with a stirring blade so that the pH in the reaction vessel became 10.6 and the ammonium ion concentration became 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 vessel was 1000 rpm, and the temperature of the liquid in the reaction vessel was kept at 60 °C by a water jacket for heat insulation. In addition, nitrogen gas was introduced into the reaction vessel to prevent oxidation of the coprecipitate produced in the crystallization reaction. The gas introduced into the reaction vessel can be used not only the above 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 dryer. Thus, 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 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.

[0045] (Example 8) 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 Ca concentration of this mixed metal salt solution was 0.005 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 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 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 was 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 crucible and fired in a muffle furnace at 500 °C for 8 hours in an oxygen atmosphere, then heated to 740 °C and held at that temperature for 4 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 = 90:7:3, and a 1.5 mol / L mixed metal salt solution was prepared. The Ca concentration of this mixed metal salt solution was 0.004 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 11.0 and the ammonium ion concentration was 7.2 g / L, and a crystallization reaction was carried out to precipitate a nickel-cobalt-manganese composite hydroxide compound. At this time, the rotation speed of the stirring blade of the reaction tank was 820 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 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, 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 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 was 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 crucible and fired in a muffle furnace at 500 °C for 8 hours in an oxygen atmosphere, then heated to 720 °C and held at that temperature for 4 hours to perform firing, thereby obtaining a positive electrode active material.

[0047] (Example 10) 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 Ca concentration of this mixed metal salt solution was 0.004 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 heat was retained 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 gases that do 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 metal atoms 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 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 to 720°C and held at this temperature for 4 hours to perform firing, and a positive electrode active material was obtained.

[0048] (Composition) Regarding the powders of the precursors and positive electrode active materials of Examples 1 to 10, the compositions were measured as follows. For the nickel, cobalt, and manganese compositions, the obtained respective precursors and samples (powders) of each cathode active material were weighed in a specified amount, decomposed by the 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. Also, for the calcium composition of the precursors and cathode active materials, the obtained respective precursors and samples (powders) of each cathode 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.

[0049] (Average particle size D50) For the powders of the precursors and cathode active materials of Examples 1 to 10, the average particle size D50 was measured as follows. 100 mg of each of the obtained precursors and samples (powders) of each cathode active material was irradiated with 40 W of ultrasonic waves for 60 seconds in a 50% flow rate using a laser diffraction particle size distribution analyzer "MT3300EXII" manufactured by Microtrac, and after dispersion, 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 cathode active material powder. Note that 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.

[0050] (Tap density) For the powders of the precursors and cathode active materials of Examples 1 to 10, the tap density was measured as follows. 5 g of each of the obtained precursors and samples (powders) of each cathode active material was put into a 10 cc graduated cylinder, placed in a powder density measuring instrument "KYT-4000K" manufactured by Seishin Enterprise Co., Ltd., and after performing 1500 taps with a stroke length of 55 mm, the scale 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).

[0051] (BET specific surface area) For the precursors and the powders of the cathode active materials of Examples 1 to 10, the BET specific surface areas were measured as follows respectively. 1.0 g of each obtained precursor and each sample (powder) of the cathode active material were weighed into a glass cell, set in a degassing apparatus, filled with nitrogen gas in the glass cell, and then heat-treated at 40 °C for 20 minutes in a nitrogen gas atmosphere for degassing. Then, the glass cell containing the degassed sample (powder) was set to 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 was measured by the BET method (one-point method).

[0052] (c-axis lattice constant) For the powders of the cathode active materials of Examples 1 to 10, 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) ·Coat the sample (cathode active material) on a glass sample holder (2 cm × 1.5 cm, depth 0.3 mm) ·Detector: D / tex ·Measurement range: 2θ = 10° - 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) of the XRD diffraction pattern measured under the above conditions.

[0053] (Discharge Capacity) For the powders of the positive electrode active materials of Examples 1 to 10, the discharge capacities were measured as follows respectively. The obtained positive electrode active material, a conductive material (acetylene black), and a binder (polyvinylidene fluoride) were weighed at a ratio of 90:5:5. The positive electrode material and the conductive material were mixed with the binder dissolved in an organic solvent (N-methylpyrrolidone) to form a slurry, which was then coated on an Al foil, dried, and pressed to obtain a positive electrode. Subsequently, a 2032-type coin cell for evaluation with Li as the counter electrode was fabricated, and using an electrolyte solution prepared by dissolving 1 M-LiPF6 in EC-DMC (3:7), the initial battery characteristics at 25°C (charge capacity, discharge capacity, charge-discharge characteristics) were measured. 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 the above Examples 1 to 10 are shown in Tables 1 and 2.

[0054] [Table 1]

[0055] [Table 2]

[0056] (Evaluation Results) The positive electrode active materials of Examples 1 to 10 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 positive electrode active material. Compositional formula: Li a Ni (1-b-c-d) Co b Mn c Ca d O 2 (In the above formula, 0.98 ≤ a ≤ 1.09, 0.06 ≤ b ≤ 0.21, 0.02 ≤ c ≤ 0.32, 0.000002 ≤ d ≤ 0.0007.) Moreover, the positive electrode active materials of Examples 1 to 10 all had a 50% cumulative volume particle size D50 of 3.0 to 11.0 μm, a tap density of 2.0 to 2.6 g / cc, a c-axis lattice constant satisfying 14.180 to 14.255 Å, and good battery characteristics (discharge capacity).

Claims

1. Composition formula: Li a Ni (1-b-c-d) Co b Mn c Ca d O 2 (In the above formula, 0.98 ≤ a ≤ 1.09, 0.06 ≤ b ≤ 0.21, 0.02 ≤ c ≤ 0.32, 0.000002 ≤ d ≤ 0.0007.) 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 for a lithium ion battery according to Claim 3 and a negative electrode.

5. (a) An aqueous solution containing a nickel salt, (b) a cobalt salt, (c) a manganese salt, and (d) a calcium salt, and (e) a basic aqueous solution containing ammonia and / or a basic aqueous solution of an alkali metal 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 Ca d (OH) 2 (In the above formula, 0.06 ≤ b ≤ 0.21, 0.02 ≤ c ≤ 0.32, 0.00001 ≤ d ≤ 0.0007.) 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 for 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 ), the number of lithium atoms (Li n ), (Li n / Me n ) is 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 further firing 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.

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