WO2011065391A1

WO2011065391A1 - Positive electrode active material for lithium secondary battery, method for producing same, and lithium secondary battery

Info

Publication number: WO2011065391A1
Application number: PCT/JP2010/070962
Authority: WO
Inventors: 政博菊池
Original assignee: 日本化学工業株式会社
Priority date: 2009-11-26
Filing date: 2010-11-25
Publication date: 2011-06-03
Also published as: KR20120114232A; JP2011113792A; CN102668187A

Abstract

Disclosed is a positive electrode active material for a lithium secondary battery, which uses a lithium nickel manganese cobalt complex oxide that is capable of providing a lithium secondary battery with particularly excellent cycle characteristics, load characteristics and safety. Specifically disclosed is a positive electrode active material for a lithium secondary battery, which is characterized by being composed of a lithium complex oxide that is obtained by having a lithium nickel manganese cobalt complex oxide represented by the following general formula (1): Li_xNi_yMn_zCo_1-y-zO_1+x (wherein, x satisfies 1.02 ≤ x ≤ 1.25, y satisfies 0.30 ≤ y ≤ 0.40, and z satisfies 0.30 ≤ z ≤ 0.40) contain one or more kinds of metal atoms (Me) selected from among Mg, Al, Ti, Cu and Zr in an amount of 0.1% by mole or more but less than 5% by mole. The positive electrode active material for a lithium secondary battery is also characterized in that the amount of Li₂CO₃ present on the particle surfaces is 0.05-0.20% by weight.

Description

Positive electrode active material for lithium secondary battery, method for producing the same, and lithium secondary battery

The present invention relates to a positive electrode active material for a lithium secondary battery and a lithium secondary battery using the positive electrode active material for a lithium secondary battery, particularly excellent in cycle characteristics, load characteristics, and safety.

Conventionally, lithium cobaltate has been used as a positive electrode active material for lithium secondary batteries. However, since cobalt is a rare metal, lithium nickel manganese cobalt-based composite oxides having a low cobalt content (see, for example, Patent Documents 1 to 3) have been developed.

Lithium secondary batteries that use this lithium nickel manganese cobalt based composite oxide as the positive electrode active material can be manufactured at low cost by adjusting the atomic ratio of nickel, manganese, and cobalt contained in the composite oxide. However, there is a demand for improved cycle characteristics, load characteristics, and safety.

Further, in Patent Documents 4 and 5 below, it is proposed to use a carbonated Li-excess layered lithium nickel composite oxide having a defined carbonate ion concentration as a positive electrode active material. There is no description or suggestion about using a lithium nickel manganese cobalt composite oxide having a composition.

Japanese Patent Laid-Open No. 04-106875 International Publication No. 2004/092073 Pamphlet JP 2005-25975 A JP 2004-335345 A JP 2009-4311 A

As a result of intensive studies in view of the above circumstances, the present inventors have obtained a lithium composite oxide containing a specific metal atom in a specific range in a lithium nickel manganese cobalt composite oxide having a specific composition as a positive electrode active material. The lithium secondary battery shall be excellent in safety. Furthermore, it has been found that by adjusting the amount of Li ₂ CO ₃ present on the particle surface of the lithium composite oxide within a specific range, the capacity retention rate of lithium secondary batteries, particularly at high temperatures, can be dramatically improved. Completed the invention.

That is, an object of the present invention is to provide a positive electrode active for a lithium secondary battery using a lithium nickel manganese cobalt based composite oxide capable of imparting particularly excellent cycle characteristics, load characteristics, and safety to a lithium secondary battery. An object of the present invention is to provide a lithium secondary battery excellent in cycle characteristics, load characteristics, and safety, using a positive electrode active material, and a material, a method for producing the positive electrode active material in an industrially advantageous manner.

The first invention to be provided by the present invention is the following general formula (1):
Li _x Ni _y Mn _z Co _1-yz O _{1 + x} (1)
(Wherein x represents 1.02 ≦ x ≦ 1.25, y represents 0.30 ≦ y ≦ 0.40, and z represents 0.30 ≦ z ≦ 0.40). A lithium composite oxide in which one or more metal atoms (Me) selected from Mg, Al, Ti, Cu and Zr are contained in a cobalt-based composite oxide in an amount of 0.1 mol% or more and less than 5 mol%. A positive electrode active material for a lithium secondary battery, characterized in that the amount of Li ₂ CO ₃ present on the particle surface is 0.05 to 0.20% by weight.

The second invention to be provided by the present invention is:
(A) a lithium compound and (b) a general formula; Ni _y Mn _z Co _1-yz (OH) ₂
(Wherein y represents 0.30 ≦ y ≦ 0.40, z represents 0.30 ≦ z ≦ 0.40), and (c) Mg, Al, Ti, One or more metal atom (Me) -containing compounds selected from Cu and Zr have an atomic ratio of Li / (Ni + Mn + Co + Me) of 1.02 to 1.25 and an atomic ratio of Me / (Ni + Mn + Co) A lithium secondary battery comprising: a first step of mixing at 0.001 to less than 0.05; and then a second step of firing the obtained mixture at 800 to 1000 ° C. to obtain a lithium composite oxide It is a manufacturing method of the positive electrode active material.

The third invention to be provided by the present invention is a lithium secondary battery using the positive electrode active material for lithium secondary battery according to the first invention.

ADVANTAGE OF THE INVENTION According to this invention, the lithium secondary battery which has the outstanding cycling characteristics, load characteristics, and safety | security can be provided using the positive electrode active material which consists of lithium nickel manganese cobalt type complex oxide. In particular, the present invention can provide a lithium secondary battery having excellent cycle characteristics even at high temperatures.
Moreover, according to the manufacturing method of this positive electrode active material for lithium secondary batteries, this positive electrode active material can be manufactured by an industrially advantageous method.

The X-ray diffraction pattern of the composite hydroxide sample A. X-ray diffraction diagram of composite hydroxide sample B. FIG. FIG. 4 is an X-ray diffraction pattern of the lithium composite oxide obtained in Example 3. The DSC chart of this lithium composite oxide sample when the lithium composite oxide sample of Example 3 is used as a positive electrode active material and safety is evaluated. The DSC chart of this lithium composite oxide sample when the lithium composite oxide sample of the comparative example 1 is used as a positive electrode active material and safety is evaluated. The DSC chart of this lithium composite oxide sample when the lithium composite oxide sample of the comparative example 3 is used as a positive electrode active material, and safety is evaluated.

Hereinafter, the present invention will be described based on preferred embodiments thereof.
The positive electrode active material for a lithium secondary battery according to the present invention (hereinafter simply referred to as “positive electrode active material” unless otherwise specified) is represented by the following general formula (1):
Li _x Ni _y Mn _z Co _1-yz O _{1 + x} (1)
(Wherein x represents 1.02 ≦ x ≦ 1.25, y represents 0.30 ≦ y ≦ 0.40, and z represents 0.30 ≦ z ≦ 0.40). Lithium in which a specific metal atom (Me) is contained in an amount of 0.1 mol% to less than 5 mol% in a cobalt-based composite oxide (hereinafter sometimes simply referred to as “lithium nickel manganese cobalt-based composite oxide”) It is a composite oxide (hereinafter sometimes simply referred to as “lithium composite oxide”).

X in the formula of the lithium composite oxide represented by the general formula (1) is 1.02 or more and 1.25 or less, and particularly x in the formula is in the range of 1.05 or more and 1.20 or less. This is preferable from the viewpoint of improving the capacity retention rate of the lithium secondary battery. Y and Z in the formula are 0.30 or more and 0.40 or less, and when y and z in the formula are in the range of 0.33 or more and 0.34 or less, the target product can be produced at low cost. Moreover, it is preferable from the viewpoint of improving the safety of the lithium secondary battery.

The metal atom (Me) contained in the lithium nickel manganese cobalt composite oxide represented by the general formula (1) is one or more metal atoms selected from Mg, Al, Ti, Cu and Zr ( Me) (hereinafter sometimes simply referred to as “metal atom (Me)”), among which Mg, Ti, and Cu are particularly preferable from the viewpoint of further improving the safety of the lithium secondary battery. Further, the amount of metal atom (Me) contained in the lithium nickel manganese cobalt based composite oxide is 0.1 mol% or more and less than 5 mol%. In particular, the content of the metal atom (Me) is preferably 0.2 mol% or more and 1 mol% or less from the viewpoint of obtaining a lithium secondary battery having high discharge capacity and further improved safety. In the present invention, the reason why the content of the metal atom (Me) is within the above range is that when the content of the metal atom (Me) is smaller than 0.1 mol%, the safety improvement effect of the lithium secondary battery is improved. On the other hand, when the content of the metal atom (Me) is 5 mol% or more, the discharge capacity of the lithium secondary battery is lowered.
In the present invention, the metal atom (Me) may be contained as a solid solution in the lithium nickel manganese cobalt-based composite oxide. It may exist on the particle surface of the composite oxide.

In the lithium composite oxide according to the positive electrode active material of the present invention, the amount of Li ₂ CO ₃ present on the particle surface of the lithium composite oxide is 0.05 to 0.20% by weight, preferably 0.07 to 0. 20% by weight. The reason for this is that when the amount of Li ₂ CO ₃ present on the particle surface of the lithium composite oxide is less than 0.05% by weight, the formation of a film by the decomposition of the electrolyte solution on the electrode surface is promoted, and the capacity retention rate is increased. On the other hand, if it exceeds 0.20% by weight, the amount of CO ₂ gas generated during high-temperature storage increases and the safety of the lithium secondary battery decreases.

The amount of Li ₂ CO ₃ present on the particle surface of the lithium composite oxide is 1.5 to 10 mg / m ² , preferably the amount of Li ₂ CO ₃ present on the particle surface per unit area determined from the BET specific surface area. Is preferably from 2.5 to 7.0 mg / m ² from the viewpoint of further improving the capacity retention rate at high temperatures of a lithium secondary battery using the positive electrode active material.

Further, the lithium composite oxide according to the positive electrode active material of the present invention is such that the remaining LiOH is 0.15% by weight or less, preferably 0.11% by weight or less and substantially free of LiOH. Is preferable from the viewpoint of facilitating electrode preparation because the coating property is stable and coating properties are improved.

In the positive electrode active material according to the present invention, the lithium composite oxide has an average particle size of 1 to 30 μm, preferably 3 to 20 μm, determined by a laser particle size distribution measurement method. The reason for this is that when the average particle size of the lithium composite oxide is smaller than 1 μm, the number of highly active fine particles tends to increase, and the effect of improving the safety of the lithium secondary battery tends to be difficult to obtain. This is because applicability to the electrodes tends to be a problem when the size is increased.

The lithium composite oxide has a BET specific surface area of 0.1 to 1 m ² / g, preferably 0.2 to 0.8 m ² / g. The reason for this is that when the BET specific surface area of the lithium composite oxide is smaller than 0.1 m ² / g, the load characteristics of the lithium secondary battery tend to deteriorate, whereas when the lithium composite oxide is larger than 1 m ² / g, the lithium secondary battery This is because the discharge capacity tends to decrease.

The lithium composite oxide has a tap density of 1.5 g / ml or more. This is because when the tap density of the lithium composite oxide is less than 1.5 g / ml, the electrode density tends to decrease and the discharge capacity of the lithium secondary battery tends to decrease. In particular, when the tap density of the lithium composite oxide is in the range of 1.7 to 2.8 g / ml, it is particularly preferable from the viewpoint of increasing the discharge capacity of the lithium secondary battery.

The positive electrode active material of the present invention includes, for example, (a) a lithium compound, (b) a general formula; Ni _y Mn _z Co _1-yz (OH) ₂ (wherein y is 0.30 ≦ y ≦ 0. 40, z represents 0.30 ≦ z ≦ 0.40), and (c) the metal atom (Me) -containing compound has an atomic ratio of Li / (Ni + Mn + Co + Me) of 1. The first step of mixing at 0.002 to 1.25 and the atomic ratio of Me / (Ni + Mn + Co) not less than 0.001 and less than 0.05, and then the resulting mixture is calcined at 800 to 1000 ° C. to oxidize lithium composite By having the 2nd process of obtaining a thing, it can manufacture.

Examples of the (a) lithium compound according to the first step include lithium oxide, hydroxide, carbonate, nitrate, and organic acid salt. Among these, lithium carbonate is easy to handle as a powder, It is particularly preferably used from the viewpoint of being inexpensive. Further, this lithium compound has an average particle size determined by a laser light scattering method of 1 to 100 μm, and preferably 5 to 80 μm, because of good reactivity.

In the formula of the composite hydroxide (hereinafter referred to as “composite hydroxide”) represented by the general formula (b) Ni _y Mn _z Co _1-yz (OH) _{2 according} to the first step. y and z correspond to y and z in the formula of the general formula (1), respectively, and y and Z are 0.30 or more and 0.40 or less, and particularly y and z in the formula are 0. In the range of 0.33 or more and 0.34 or less, the target lithium composite oxide can be produced at low cost, and the obtained lithium composite oxide further improves the safety of the lithium secondary battery. From the viewpoint of being able to do so.

The composite hydroxide has an average particle size determined by a laser particle size distribution measurement method of 1 to 30 μm, preferably 3 to 20 μm. The reason for this is that when the average particle size of the composite hydroxide is smaller than 1 μm, in the lithium secondary battery using the obtained lithium composite oxide as a positive electrode active material, the safety improvement effect tends to be small. On the other hand, when the average particle size is larger than 30 μm, the reactivity is deteriorated, and in the lithium secondary battery using the obtained lithium composite oxide as a positive electrode active material, the discharge capacity tends to decrease.

The composite hydroxide has a BET specific surface area of 2 to 10 m ² / g, preferably 2 to 8 m ² / g. The reason for this is that when the BET specific surface area of the composite hydroxide is smaller than 2 m ² / g, the reactivity becomes worse, and in the lithium secondary battery using the obtained lithium composite oxide as a positive electrode active material, On the other hand, when the BET specific surface area is larger than 10 m ² / g, in the lithium secondary battery using the obtained lithium composite oxide as the positive electrode active material, the safety improvement effect tends to be small. Because there is.

The composite hydroxide has a tap density of 1 g / ml or more, preferably 1.5 to 2.5 g / ml. The reason for this is that if the tap density of the composite hydroxide is less than 1 g / ml, the tap density and electrode density of the obtained lithium composite oxide are reduced, and thus the obtained lithium composite oxide is used as a positive electrode active material. This is because the discharge capacity tends to decrease in the lithium secondary battery.

The composite hydroxide having such various physical properties can be prepared, for example, by a coprecipitation method. Specifically, the composite hydroxide can be coprecipitated by mixing an aqueous solution containing a predetermined amount of nickel atom, cobalt atom and manganese atom, an aqueous solution of a complexing agent, and an alkaline aqueous solution ( (See JP-A-10-81521, JP-A-10-81520, JP-A-10-29820, 2002-201028, etc.). The composite hydroxide may be a commercial product.

Further, the present inventor selects and uses a composite hydroxide characterized by a diffraction peak in X-ray diffraction analysis, and uses the resulting lithium secondary battery as a positive electrode active material. It has been found that the discharge capacity at high temperature and the load characteristics are improved. That is, the composite hydroxide used has an intensity ratio (A ₁ ) between a diffraction peak (A ₁ ) near 2θ = 38 ° and a diffraction peak (B ₁ ) near 2θ = 19 ° in an X-ray diffraction analysis using CuKα rays. It is particularly preferred to select and use those having a / B ₁ ) of 0.4 or less, preferably 0.2 or less. The diffraction peak (A ₁ ) near 2θ = 38 ° indicates a diffraction peak at 38 ± 0.5 °. The diffraction peak around 2θ = 19 ° indicates a diffraction peak at 19 ± 0.5 °.

(C) 1 type, or 2 or more types of metal atom (Me) containing compound chosen from Mg, Al, Ti, Cu, and Zr which concerns on 1st process is an oxide containing these metal atoms (Me), water Oxides, halides, carbonates, nitrates, organic acid salts and the like can be used. In addition, this metal atom (Me) -containing compound has an average particle size determined by a laser particle size distribution measuring method of 0.1 to 20 μm, preferably 0.1 to 10 μm, since it has good reactivity and is particularly preferable.

The raw material (a) lithium compound, (b) composite hydroxide, and (c) metal atom (Me) -containing compound contain as much impurities as possible in order to produce a high-purity positive electrode active material. Those with less are preferred.

In the reaction operation according to the first step, first, (a) a lithium compound, (b) a composite hydroxide, and (c) a metal atom (Me) -containing compound are mixed in a predetermined amount to obtain a uniform mixture.

The compounding ratio of (a) lithium compound, (b) composite hydroxide and (c) metal atom (Me) -containing compound is the atomic ratio of lithium atom to nickel atom, cobalt atom, manganese atom and metal atom (Me) ( Li / (Ni + Co + Mn + Me)) is 1.02 to 1.25, preferably 1.05 to 1.20, in order to obtain a positive electrode active material having excellent cycle characteristics, load characteristics and safety. An important requirement. The reason for this is that when the atomic ratio of lithium atoms to nickel atoms, cobalt atoms, manganese atoms, and metal atoms (Me) is smaller than 1.02, the amount of Li ₂ CO ₃ present on the particle surface of the resulting lithium composite oxide This is because it is difficult to enter the range of 0.05 to 0.20% by weight. On the other hand, when the atomic ratio of lithium atoms to nickel atoms, cobalt atoms, manganese atoms, and metal atoms (Me) is greater than 1.25, the discharge capacity of the lithium secondary battery is greatly reduced.

The compounding ratio of (b) the composite hydroxide and (c) the metal atom (Me) -containing compound is the atomic ratio of the metal atom (Me) to the nickel atom, cobalt atom and manganese atom (Me / {Ni + Mn + Co}). Viewpoint of obtaining a lithium secondary battery that has a high capacity retention rate and is excellent in safety, particularly when the capacity is 0.001 or more and less than 0.05, and particularly 0.002 or more and 0.01 or less. To preferred. The reason why the atomic ratio of the metal atom (Me) to the nickel atom, cobalt atom, and manganese atom is within the above range is that when the atomic ratio of Me / (Ni + Mn + Co) is smaller than 0.01, the safety of the lithium secondary battery is reduced. This is because the improvement effect is not observed, and on the other hand, when the atomic ratio of Me / (Ni + Mn + Co) is 0.05 or more, the discharge capacity of the lithium secondary battery decreases.

The mixing may be either a dry method or a wet method, but a dry method is preferable because of easy production. In the case of dry mixing, it is preferable to use a blender or the like that uniformly mixes the raw materials.

The mixture obtained by uniformly mixing the raw materials obtained in the first step is then subjected to a second step to obtain a positive electrode active material made of a lithium composite oxide.

The second step according to the present invention is a step of obtaining a positive electrode active material made of a lithium composite oxide by firing the mixture obtained by uniformly mixing the raw materials obtained in the first step in a specific temperature range.

The firing temperature in the second step is 800 to 1000 ° C., preferably 850 to 950 ° C. This is because when the firing temperature is lower than 800 ° C., the solid solution reaction between (a) the lithium compound, (b) the composite hydroxide, and (c) the metal atom (Me) -containing compound is not completed. Lithium secondary batteries having a lithium composite oxide as a positive electrode active material have a low discharge capacity, and it is difficult to obtain a battery with excellent load characteristics and safety. On the other hand, when the firing temperature is higher than 1000 ° C., the obtained lithium This is because it is difficult to obtain a lithium secondary battery using a composite oxide as a positive electrode active material with good load characteristics.

The firing atmosphere may be an air atmosphere or an oxygen atmosphere, and the firing time is 5 hours or longer, preferably 7 to 15 hours.
Moreover, in this invention, you may perform baking as many times as desired. Alternatively, for the purpose of making the powder characteristics uniform, the fired material may be pulverized and then refired.
After firing, the lithium composite oxide of the present invention is obtained by appropriately cooling and pulverizing as necessary.

The pulverization is appropriately performed when the obtained lithium composite oxide is brittle and in a block shape, and the lithium composite oxide has specific powder characteristics. That is, the average particle size determined by the laser particle size distribution measurement method is 1 to 30 μm, preferably 3 to 20 μm, and the BET specific surface area is 0.1 to 1 m ² / g, preferably 0.2 to 0.8 m ² /. g, the tap density is 1.5 g / ml or more, preferably 1.7 to 2.8 g / ml.
On the particle surface of the lithium composite oxide thus obtained, Li ₂ CO ₃ is present in an amount of 0.05 to 0.15 wt%, and LiOH is also present in an amount of 0.02 to 0.15 wt%.

In the present invention, subjected to the third step, converted to LiOH to _Li 2 CO _3, enhance the _Li 2 CO ₃ amount up to 0.07 to 0.20 wt%, and up to 0.11 wt% or less LiOH It can be reduced. The lithium secondary battery using the positive electrode active material obtained by applying the third step further improves battery performance such as cycle characteristics, load characteristics and safety.

In the third step, the lithium composite oxide obtained in the second step is brought into contact with carbon dioxide.

The contact between the lithium composite oxide and carbon dioxide is performed in an atmosphere containing a carbon dioxide concentration of 50% by volume or more, preferably 90 to 100% by volume. This is because if the carbon dioxide concentration is smaller than 50% by volume, the conversion to Li ₂ CO ₃ tends to be insufficient. The contact between the lithium nickel manganese cobalt composite oxide and carbon dioxide can be efficiently converted to Li ₂ CO ₃ by performing stirring or moderate vibration.

The contact temperature is 5 to 90 ° C., preferably 10 to 80 ° C., for 5 minutes or more, preferably 0.1 to 10 hours.

After completion of the third step, the product is dried, crushed or crushed as necessary, and then classified to obtain a product.

In addition, it is possible to remove the water generated when the LiOH is converted to Li ₂ CO ₃ by performing the drying treatment, and the lithium composite oxide from which the water is removed in this way is used as a positive electrode active material. The secondary battery is further improved in discharge capacity, load characteristics and safety. The drying treatment temperature is preferably from 100 to 300 ° C., preferably from 150 to 250 ° C., from the viewpoint that moisture can be quickly removed. The drying time is 30 minutes or longer, preferably 1 to 2 hours.

A lithium secondary battery according to the present invention uses the above-described positive electrode active material for a lithium secondary battery, and includes a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte containing a lithium salt. The positive electrode is formed, for example, by applying and drying a positive electrode mixture on a positive electrode current collector, and the positive electrode mixture includes a positive electrode active material, a conductive agent, a binder, and a filler added as necessary. Consists of. In the lithium secondary battery according to the present invention, the positive electrode active material made of the lithium composite oxide of the present invention is uniformly applied to the positive electrode. For this reason, the lithium secondary battery according to the present invention is particularly excellent in load characteristics, capacity retention at high temperatures, and safety.

The content of the positive electrode active material contained in the positive electrode mixture is 70 to 100% by weight, preferably 90 to 98% by weight.

The positive electrode current collector is not particularly limited as long as it is an electronic conductor that does not cause a chemical change in the constituted battery. For example, stainless steel, nickel, aluminum, titanium, calcined carbon, aluminum, and stainless steel Examples of the surface include carbon, nickel, titanium, and silver surface-treated. The surface of these materials may be oxidized and used, or the current collector surface may be provided with irregularities by surface treatment. Examples of the current collector include foils, films, sheets, nets, punched ones, lath bodies, porous bodies, foam bodies, fiber groups, nonwoven fabric molded bodies, and the like. The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm.

The conductive agent is not particularly limited as long as it is an electron conductive material that does not cause a chemical change in a configured battery. For example, graphite such as natural graphite and artificial graphite, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, carbon black such as thermal black, conductive fibers such as carbon fiber and metal fiber, Examples include metal powders such as carbon fluoride, aluminum and nickel powder, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and conductive materials such as polyphenylene derivatives. Examples of graphite include scaly graphite, scaly graphite, and earthy graphite. These can be used alone or in combination of two or more. The blending ratio of the conductive agent is 1 to 50% by weight, preferably 2 to 30% by weight in the positive electrode mixture.

Examples of the binder include starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, regenerated cellulose, diacetylcellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer ( EPDM), sulfonated EPDM, styrene butadiene rubber, fluoro rubber, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, fluorinated Vinylidene-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetraf Oroethylene copolymer, polychlorotrifluoroethylene, vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetra Fluoroethylene copolymer, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer or its (Na ⁺ ) ion cross-linked product, ethylene-methacrylic acid copolymer or its (Na ⁺ ) Ionic cross-linked product, ethylene-methyl acrylate copolymer or its (Na ⁺ ) ionic cross-linked product, ethylene-methyl methacrylate copolymer or its (Na ⁺ ) ionic cross-linked product, polysaccharides such as polyethylene oxide, heat Plastic tree , Polymers having rubber elasticity, and these may be used individually or in combination. In addition, when using the compound containing a functional group which reacts with lithium like a polysaccharide, it is preferable to add the compound like an isocyanate group and to deactivate the functional group, for example. The blending ratio of the binder is 1 to 50% by weight, preferably 5 to 15% by weight in the positive electrode mixture.

The filler suppresses the volume expansion of the positive electrode in the positive electrode mixture, and is added if necessary. As the filler, any fibrous material can be used as long as it does not cause a chemical change in the constructed battery. For example, olefinic polymers such as polypropylene and polyethylene, and fibers such as glass and carbon are used. The addition amount of the filler is not particularly limited, but is preferably 0 to 30% by weight in the positive electrode mixture.

The negative electrode is formed by applying and drying a negative electrode material on the negative electrode current collector. The negative electrode current collector is not particularly limited as long as it is an electronic conductor that does not cause a chemical change in a configured battery. For example, stainless steel, nickel, copper, titanium, aluminum, calcined carbon, copper or stainless steel Examples of the steel surface include carbon, nickel, titanium, silver surface-treated, and an aluminum-cadmium alloy. Further, the surface of these materials may be used after being oxidized, or the surface of the current collector may be provided with irregularities by surface treatment. Examples of the current collector include foils, films, sheets, nets, punched ones, lath bodies, porous bodies, foam bodies, fiber groups, nonwoven fabric molded bodies, and the like. The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm.

The negative electrode material is not particularly limited, and examples thereof include carbonaceous materials, metal composite oxides, lithium metals, lithium alloys, silicon-based alloys, tin-based alloys, metal oxides, conductive polymers, and chalcogen compounds. And Li—Co—Ni-based materials. Examples of the carbonaceous material include non-graphitizable carbon materials and graphite-based carbon materials. Examples of the metal composite oxide include Sn _P (M ¹ ) _1-p (M ² ) _q _Or (wherein M ¹ represents one or more elements selected from Mn, Fe, Pb and Ge, M ² represents one or more elements selected from Al, B, P, Si, Group 1, Group 2, Group 3 and a halogen element in the periodic table, and 0 <p ≦ 1, 1 ≦ q ≦ 3 ,. showing a 1 ≦ r ≦ 8), Li x Fe 2 O 3 (0 ≦ x ≦ 1), Li x WO 2 (0 ≦ x ≦ 1), include compounds of lithium titanate. As the metal _{oxide, GeO, GeO 2, SnO,} SnO 2, PbO, PbO 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, Bi 2 O 3 Bi ₂ O ₄ , Bi ₂ O _{5 and the} like. Examples of the conductive polymer include polyacetylene and poly-p-phenylene.

As the separator, an insulating thin film having a large ion permeability and a predetermined mechanical strength is used. Sheets and non-woven fabrics made of olefin polymers such as polypropylene, glass fibers or polyethylene are used because of their organic solvent resistance and hydrophobicity. The pore diameter of the separator may be in a range generally useful for batteries, for example, 0.01 to 10 μm. The thickness of the separator may be in a range for a general battery, for example, 5 to 300 μm. When a solid electrolyte such as a polymer is used as the electrolyte described later, the solid electrolyte may also serve as a separator.

The non-aqueous electrolyte containing a lithium salt is composed of a non-aqueous electrolyte and a lithium salt. As the non-aqueous electrolyte, a non-aqueous electrolyte, an organic solid electrolyte, or an inorganic solid electrolyte is used. Non-aqueous electrolytes include, for example, N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyl Tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 3-methyl -2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, 1,3- Ropansaruton, methyl propionate, and a solvent obtained by mixing one or more aprotic organic solvents such as ethyl propionate.

Examples of the organic solid electrolyte include a polyethylene derivative, a polyethylene oxide derivative or a polymer containing the same, a polypropylene oxide derivative or a polymer containing the same, a phosphate ester polymer, polyphosphazene, polyaziridine, polyethylene sulfide, polyvinyl alcohol, polyvinylidene fluoride, Examples thereof include a polymer containing an ionic dissociation group such as polyhexafluoropropylene, and a mixture of a polymer containing an ionic dissociation group and the above non-aqueous electrolyte.

As the inorganic solid electrolyte, Li nitride, halide, oxyacid salt, sulfide and the like can be used, for example, Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N—LiI—LiOH, LiSiO _4. LiSiO ₄ —LiI—LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Li ₄ SiO ₄ —LiI—LiOH, P ₂ S ₅ , Li ₂ S or Li ₂ S—P ₂ S ₅ , Li ₂ S—SiS ₂ , Li ₂ S—GeS ₂ , Li ₂ S—Ga ₂ S ₃ , Li ₂ S—B ₂ S ₃ , Li ₂ S—P ₂ S ₅ —X, Li ₂ S—SiS ₂ —X, Li ₂ S —GeS ₂ —X, Li ₂ S—Ga ₂ S ₃ —X, Li ₂ S—B ₂ S ₃ —X, wherein X is at least selected from LiI, B ₂ S ₃ , or Al ₂ S ₃ One or more).

Further, when the inorganic solid electrolyte is amorphous (glass), lithium phosphate (Li ₃ PO ₄ ), lithium oxide (Li ₂ O), lithium sulfate (Li ₂ SO ₄ ), phosphorus oxide (P ₂ O ₅₎ ), Compounds containing oxygen such as lithium borate (Li ₃ BO ₃ ), Li ₃ PO _4-x N _{2x / 3} (x is 0 <x <4), Li ₄ SiO _4-x N _{2x / 3} (x is Nitrogen such as 0 <x <4), Li ₄ GeO _4-x N _{2x / 3} (x is 0 <x <4), Li ₃ BO _3-x N _{2x / 3} (x is 0 <x <3) The compound to be contained can be contained in the inorganic solid electrolyte. By adding the compound containing oxygen or the compound containing nitrogen, the gap between the formed amorphous skeletons can be widened, the hindrance to movement of lithium ions can be reduced, and ion conductivity can be further improved.

As the lithium salt, those dissolved in the non-aqueous electrolyte are used. For example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiB ₁₀ Cl ₁₀ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium tetraphenylborate, Examples thereof include salts in which one kind or two or more kinds such as imides are mixed.

Also, the following compounds can be added to the non-aqueous electrolyte for the purpose of improving discharge, charge characteristics, and flame retardancy. For example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric triamide, nitrobenzene derivative, sulfur, quinoneimine dye, N-substituted oxazolidinone and N, N-substituted imidazolidine, ethylene glycol dialkyl ether , Ammonium salt, polyethylene glycol, pyrrole, 2-methoxyethanol, aluminum trichloride, conductive polymer electrode active material monomer, triethylenephosphonamide, trialkylphosphine, morpholine, aryl compound with carbonyl group, hexamethylphosphine Examples include hollic triamide and 4-alkylmorpholine, bicyclic tertiary amines, oils, phosphonium salts and tertiary sulfonium salts, phosphazenes, carbonates, etc. That. In order to make the electrolyte nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride can be included in the electrolyte. In addition, carbon dioxide gas can be included in the electrolytic solution in order to make it suitable for high-temperature storage.

The lithium secondary battery according to the present invention is a lithium secondary battery excellent in battery performance, particularly in cycle characteristics, and the shape of the battery may be any shape such as a button, a sheet, a cylinder, a corner, or a coin type.

The use of the lithium secondary battery according to the present invention is not particularly limited. For example, a laptop computer, a laptop computer, a pocket word processor, a mobile phone, a cordless cordless handset, a portable CD player, a radio, an LCD TV, a backup power source, and an electric shaver. And electronic devices such as memory cards and video movies, and consumer electronic devices such as automobiles, electric vehicles, and game machines.

Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to these examples.

<Measurement of tap density>
Tap density is based on the method of apparent density or apparent specific volume described in JIS-K-5101, 50 g of sample is put into a 50 ml measuring cylinder, made by Yuasa Ionics, DUAL
It set to the AUTOTAP apparatus, tapped 500 times, the capacity was read, the apparent density was calculated, and it was set as the tap density.

<Measurement of average particle size>
The average particle size was determined by a laser particle size distribution measurement method.

<Composite hydroxide>
In the examples of the present invention, a commercially available aggregated hydroxide (manufactured by OMG) containing nickel, cobalt and manganese atoms having the following physical properties was used. In addition, the X-ray-diffraction figure of the following composite hydroxide sample A and composite hydroxide sample B is shown in FIG.1 and FIG.2, respectively.
Physical properties of composite hydroxide sample A (1) Ni: Co: Mn molar ratio in composite hydroxide = 0.334: 0.333: 0.333
(2) Average particle size of composite hydroxide; 10.7 μm
(3) BET specific surface area; 5.0 m ² / g
(4) Tap density; 2.3 g / ml
(5) The intensity ratio (A ₁ ) between the diffraction peak (A ₁ ) near 2θ = 38 ° and the diffraction peak (B ₁ ) near 2θ = 19 ° when X-ray diffraction analysis is performed using CuKα rays as a radiation source. / B ₁ ); 0.15

Physical Properties of Composite Hydroxide Sample B (1) Ni: Co: Mn molar ratio in composite hydroxide = 0.334: 0.333: 0.333
(2) Average particle size of composite hydroxide; 12.0 μm
(3) BET specific surface area; 3.1 m ² / g
(4) Tap density: 2.2 g / ml
(5) The intensity ratio (A ₁ ) between the diffraction peak (A ₁ ) near 2θ = 38 ° and the diffraction peak (B ₁ ) near 2θ = 19 ° when X-ray diffraction analysis is performed using CuKα rays as a radiation source. / B ₁ ); 0.45

(Examples 1 to 5, Comparative Examples 1 to 3)
The composite hydroxide sample A (Ni _0.334 Mn _0.333 Co _0.333 (OH) ₂ ), lithium carbonate (average particle size 4.5 μm) and magnesium fluoride (average particle size 5.9 μm), Nickel atoms, manganese atoms, cobalt atoms, and magnesium atoms were weighed so as to have the blending ratios shown in Table 1, and sufficiently mixed with a mixer. This mixture was fired at 900 ° C. for 10 hours in the air, and the fired product obtained by cooling after firing was pulverized and classified to obtain a lithium composite oxide sample comprising a magnesium-containing lithium nickel manganese cobalt composite oxide. It was.

(Example 6)
The composite hydroxide sample A (Ni _0.334 Mn _0.333 Co _0.333 (OH) ₂ ), lithium carbonate (average particle size 4.5 μm) and magnesium oxide (average particle size 2.9 μm) were mixed with nickel. Atoms, manganese atoms, cobalt atoms, and magnesium atoms were weighed so as to have the blending ratios shown in Table 1, and sufficiently mixed with a mixer. This mixture was fired at 900 ° C. for 10 hours in the air, and the fired product obtained by cooling after firing was pulverized and classified to obtain a lithium composite oxide sample comprising a magnesium-containing lithium nickel manganese cobalt composite oxide. It was.

(Example 7)
A lithium composite oxide sample comprising a magnesium-containing lithium nickel manganese cobalt based composite oxide was obtained under the same conditions and operating method as in Example 3 except that the composite hydroxide sample B was used instead of the composite hydroxide sample A. It was.

(Example 8)
The composite hydroxide sample A (Ni _0.334 Mn _0.333 Co _0.333 (OH) ₂ ), lithium carbonate (average particle size 4.5 μm) and copper oxide (average particle size 5.3 μm) were mixed with nickel. Atoms, manganese atoms, cobalt atoms, and copper atoms were weighed so as to have a blending ratio shown in Table 1, and sufficiently mixed with a mixer. The mixture was fired at 900 ° C. for 10 hours in the air, and the fired product obtained by cooling after firing was pulverized and classified to obtain a lithium composite oxide sample comprising a copper-containing lithium nickel manganese cobalt composite oxide. It was.

Example 9
The composite hydroxide sample A (Ni _0.334 Mn _0.333 Co _0.333 (OH) ₂ ), lithium carbonate (average particle size 4.5 μm) and titanium dioxide (average particle size 0.4 μm) were mixed with nickel. Atoms, manganese atoms, cobalt atoms, and titanium atoms were weighed so as to have the blending ratio shown in Table 1, and sufficiently mixed with a mixer. The mixture was fired at 900 ° C. for 10 hours in the air, and the fired product obtained by cooling after firing was pulverized and classified to obtain a lithium composite oxide sample comprising a titanium-containing lithium nickel manganese cobalt composite oxide. It was.

(Comparative Example 4)
A lithium composite oxide sample made of a magnesium-containing lithium nickel manganese cobalt composite oxide was obtained under the same conditions and operating method as in Example 3 except that the firing temperature was 750 ° C. for 10 hours.

(Comparative Example 5)
A lithium composite oxide sample made of a magnesium-containing lithium nickel manganese cobalt composite oxide was obtained under the same conditions and operating method as in Example 3 except that the firing temperature was 1050 ° C. for 10 hours.

Note) The molar ratio A is the molar ratio of {Li / (Ni + Mn + Co + Me)}, and the molar B is the molar ratio of {Me / (Ni + Mn + Co)}.

(Examples 10 and 11)
100 g of each of the lithium composite oxide samples obtained in Example 3 were put into a 500 ml container that can be sealed, and CO ₂ gas was sealed and sealed as an atmosphere having a carbon dioxide concentration of 95% by volume. Next, the container was attached to a vibration device (paint shaker), and was vibrated at room temperature (25 ° C.) for the treatment times shown in Table 2.
Next, the lithium composite oxide treated with CO ₂ gas was dried at 200 ° C. for 2 hours to obtain a lithium composite oxide sample with an increased Li ₂ CO ₃ content.

<Physical property evaluation>
For the lithium composite oxide samples obtained in Examples 1 to 11 and Comparative Examples 1 to 5, the average particle size, the BET specific surface area, the tap density, the amount of Li ₂ CO ₃ present on the particle surface, and the Li ₂ per unit volume The CO ₃ content and LiOH content were measured.
An X-ray diffraction pattern of the lithium composite oxide obtained in Example 3 is shown in FIG.

(Evaluation of Li ₂ CO ₃ content)
For the amount of Li ₂ CO ₃ present on the particle surface, 10 g of the obtained lithium composite oxide sample is weighed and dispersed in 100 g of pure water for 5 minutes using a magnetic stirrer. Next, the dispersion slurry is filtered, and the filtrate is recovered. Then, 50 g of the filtrate is weighed and neutralized with an automatic titrator using 0.1 N HCl to determine the Li ₂ CO ₃ content. It was.
The titer from the first end point (near pH 8) is a (ml), the titer from the first end point to the second end point (near pH 4) is b (ml), and the Li ₂ CO ₃ content is Obtained from (1).

b: Titration volume from the first end point to the second end point (around pH 4) (ml)

The amount of Li ₂ CO ₃ per unit area was obtained from the following calculation formula (2).

C: Li ₂ CO ₃ content (%) contained in the lithium nickel manganese cobalt based composite oxide sample
d: BET specific surface area (m ² / g) of lithium nickel manganese cobalt based composite oxide sample

(Evaluation of LiOH content)
The neutralization titration was performed by the titration method in the same manner as the evaluation of the Li ₂ CO ₃ content, and then obtained from the following calculation formula (3).

a: Titration volume to the first end point (around pH 8) (ml)
b: Titration volume from the first end point to the second end point (around pH 4) (ml)

<Evaluation of lithium secondary battery>
(1) Preparation of lithium secondary battery 90% by weight of the lithium composite oxide sample obtained in Examples 1 to 11 and Comparative Examples 1 to 5, 5% by weight of acetylene black, and 5% by weight of polyvinylidene fluoride were mixed. Was dispersed in N-methyl-2-pyrrolidinone to prepare a kneaded paste. The kneaded paste was applied to an aluminum foil, dried, pressed and punched into a disk with a diameter of 15 mm to obtain a positive electrode plate. In addition to this positive electrode plate, a coin-type lithium secondary battery was manufactured using each member such as a negative electrode, a separator, a current collector plate, an electrolyte, a case for CR2032, a mounting bracket, an external terminal, and the like. Of these, a lithium metal foil was used for the negative electrode, and 1 mol of LiPF ₆ was dissolved in 1 liter of a mixed solvent of 25:60:15 (v / v / v) of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in the electrolyte. We used what we did.

(2) Battery performance evaluation The produced coin-type lithium secondary battery was operated in an environment of 25 ° C and optionally 60 ° C, and the following battery performance was evaluated.

(Evaluation method of charge / discharge capacity and capacity maintenance rate)
The charging and discharging method of the coin-type lithium secondary battery is as follows. First, the battery is charged to 4.3 V at a current amount of 0.5 C (2 hour rate), and then held at 4.3 V for about 3 hours for a total constant current of 5 hours. Charging was performed by voltage (CCCV) charging, and subsequently, constant current (CC) discharging was performed to discharge to 2.7 V at a current amount of 0.2 C (5-hour rate). With these operations as one cycle, the capacity was measured every cycle. This cycle was repeated 20 times, and the capacity retention rate was calculated from the discharge capacity of the first cycle and the 20th cycle according to the following formula. The discharge capacity at the first cycle was defined as the initial discharge capacity. The results are shown in Table 5.

(Evaluation method of load characteristics)
The charging and discharging method of the coin-type lithium secondary battery is as follows. First, the battery is charged to 4.3 V at a current amount of 0.5 C (2 hour rate), and then held at 4.3 V for about 3 hours for a total constant current of 5 hours. Charging was performed by voltage (CCCV) charging, and then, constant current (CC) discharging was performed for 2 cycles at a current amount of 0.2 C (5 hour rate) to 2.7 V. In the subsequent cycles, only the current amount at the time of discharge is changed, the third cycle is 2C (1/2 hour rate), the fifth cycle is 1C (one hour rate), and the seventh cycle is 0.5C (two hour rate). Was discharged. The other cycles (4th, 6th, 8th and 9th cycles) were discharged at 0.2C, and the discharge capacity ratios of 2C, 1C and 0.5C with respect to the discharge capacity at 0.2C in the 9th cycle were calculated. The results are shown in Table 6.

(Safety evaluation method)
Safety evaluation was performed by performing differential scanning calorimetry (DSC) on the lithium composite oxide samples of Example 3, Example 6, Example 8, Example 9, Example 11, Comparative Example 1, and Comparative Example 3. evaluated.
First, the coin battery prepared above was charged to 4.4 V, recovered from the measuring machine in a charged state, disassembled in the glove box, and the positive electrode was taken out. Next, the positive electrode was cut out so that the amount of the active material was 5 mg, and placed in a pressure-resistant pan for DSC together with 10 mg of the electrolyte. The pressure pan was heated to 350 ° C. at a rate of 2 ° C./min to obtain a DSC chart. From this chart, the maximum value of the exothermic peak seen up to around 240 ° C. is P2, and the maximum value of the peak seen after around 270 ° C. is P2, and the results are shown in Table 7.
The lower values of P1 and P2 indicate that the effect of suppressing thermal runaway is higher, indicating that the safety of the lithium secondary battery is superior.
4 is a DSC chart when the lithium composite oxide sample of Example 3 is used as a positive electrode active material, and FIG. 5 is a DSC chart when the lithium composite oxide sample of Comparative Example 1 is used as a positive electrode active material. FIG. 6 shows a DSC chart when the lithium composite oxide sample of Comparative Example 3 is used as the positive electrode active material.

According to the positive electrode active material for a lithium secondary battery of the present invention, a lithium secondary battery having excellent cycle characteristics, load characteristics, and safety is provided using a positive electrode active material made of a lithium nickel manganese cobalt based composite oxide. can do. In particular, the present invention can provide a lithium secondary battery having excellent cycle characteristics even at high temperatures.
Moreover, according to the manufacturing method of this positive electrode active material for lithium secondary batteries, this positive electrode active material can be manufactured by an industrially advantageous method.

Claims

The following general formula (1):
Li x Ni y Mn z Co 1-yz O 1 + x (1)
(Wherein x represents 1.02 ≦ x ≦ 1.25, y represents 0.30 ≦ y ≦ 0.40, and z represents 0.30 ≦ z ≦ 0.40). A lithium composite oxide in which one or more metal atoms (Me) selected from Mg, Al, Ti, Cu and Zr are contained in a cobalt-based composite oxide in an amount of 0.1 mol% or more and less than 5 mol%. A positive electrode active material for a lithium secondary battery, wherein the amount of Li 2 CO 3 present on the particle surface is 0.05 to 0.20 wt%.
2. The lithium composite oxide according to claim 1, wherein the average particle diameter is 1 to 30 μm, the BET specific surface area is 0.1 to 1 m 2 / g, and the tap density is 1.5 g / ml or more. Positive electrode active material for lithium secondary battery.
3. The positive electrode for a lithium secondary battery according to claim 1, wherein the lithium composite oxide has an amount of Li 2 CO 3 per unit area existing on the particle surface of 1.5 to 10 mg / m 2. Active material.
4. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the remaining LiOH is 0.15% by weight or less.
(A) a lithium compound and (b) a general formula; Ni y Mn z Co 1-yz (OH) 2
(Wherein y represents 0.30 ≦ y ≦ 0.40, z represents 0.30 ≦ z ≦ 0.40), and (c) a metal atom (Me) is contained. The positive electrode active material for a lithium secondary battery according to claim 1, wherein the positive electrode active material is produced by mixing a compound and firing the resulting mixture.
In the X-ray diffraction analysis by CuKα ray, the composite oxide (b) has an intensity ratio (A 1 ) between a diffraction peak (A 1 ) near 2θ = 38 ° and a diffraction peak (B 1 ) near 2θ = 19 ° (A 1 ). 1 / B 1) a positive active material for a lithium secondary battery according to claim 5, characterized in that with one of 0.4 or less.
(A) a lithium compound and (b) a general formula; Ni y Mn z Co 1-yz (OH) 2
(Wherein y represents 0.30 ≦ y ≦ 0.40, z represents 0.30 ≦ z ≦ 0.40), and (c) Mg, Al, Ti, One or more metal atom (Me) -containing compounds selected from Cu and Zr have an atomic ratio of Li / (Ni + Mn + Co + Me) of 1.02 to 1.25 and an atomic ratio of Me / (Ni + Mn + Co) A lithium secondary battery comprising: a first step of mixing at 0.001 to less than 0.05; and then a second step of firing the obtained mixture at 800 to 1000 ° C. to obtain a lithium composite oxide For producing a positive electrode active material for use.
The positive electrode active for lithium secondary batteries according to claim 7, further comprising a third step of contacting the obtained lithium composite oxide and carbon dioxide in an atmosphere having a carbon dioxide concentration of 50% by volume or more. A method for producing a substance.
The composite hydroxide (b) is characterized in that it has an average particle diameter of 1 to 30 μm, a BET specific surface area of 2 to 10 m 2 / g, and a tap density of 1 g / ml or more. 8. A method for producing a positive electrode active material for a lithium secondary battery according to 8.
In the X-ray diffraction analysis of the composite hydroxide (b) by CuKα ray, the intensity ratio (A 1 ) between the diffraction peak (A 1 ) near 2θ = 38 ° and the diffraction peak (B 1 ) near 2θ = 19 ° The method for producing a positive electrode active material for a lithium secondary battery according to claim 7, wherein / B 1 ) is 0.4 or less.
A lithium secondary battery using the positive electrode active material for a lithium secondary battery according to any one of claims 1 to 6.