JP2003034536A - Method for producing laminar lithium nickel manganese complex oxide powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a laminar lithium nickel manganese complex oxide powder, which has a high bulk density and is preferably used for the positive electrode active substance of lithium secondary cell. SOLUTION: A slurry contains at least a lithium source compound, a nickel source compound, and a manganese source compound, which are crushed and mixed, in a weight ratio of nickel atom [Ni] to manganese atom [Mn] of 0.7 to 90. The slurry is dried through spray drying and is fired to obtain a laminar lithium nickel manganese complex oxide powder and thereafter is pulverized to obtain the product laminar lithium nickel manganese complex oxide powder.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a layered lithium nickel manganese composite oxide powder, and particularly to a layered lithium nickel manganese having a high bulk density and suitable for use as a positive electrode active material of a lithium secondary battery. The present invention relates to a method for producing a composite oxide powder.

[0002]

2. Description of the Related Art Conventionally, lithium secondary batteries are excellent in high energy density and high output density and can be made compact and lightweight, so that they are used as a power source for portable devices such as laptop computers, mobile phones and handy video cameras. The positive electrode active material of the lithium secondary battery, which shows a rapid growth, is a composite oxide of lithium and a transition metal such as cobalt, nickel or manganese, for example, a lithium cobalt composite oxide or a lithium nickel composite oxide. , Lithium manganese composite oxides, and the like have attracted attention because they can obtain high-performance battery characteristics, and have been partially put into practical use.

Furthermore, for the purpose of stabilizing the compound oxide, increasing the capacity of the battery, improving the battery characteristics at high temperatures, etc., and considering the economical efficiency, a part of these transition metal atoms is considered. Research on various complex oxides substituted with other metal atoms is also underway, among which LiNi _1-x Mn _x O ₂
Layered lithium nickel manganese composite oxides represented by (0 <x <1) have attracted attention, and for example, Solid State Ionics
311-318 (1992), J. Mater. Chem. 1149-1155 (1996),
J. Power Sources 629-633 (1997), J. Power Sources 4
6-53 (1998) et al. Reported an example of synthesizing a single phase of a layered composite oxide with 0 ≦ x ≦ 0.5, and the 41st Battery Symposium 2D20.
(2000) reported a single-phase synthesis example in which x = 0.5, that is, Ni / Mn = 1.

On the other hand, as a method for producing these composite oxides, for example, a lithium source compound and a transition metal source compound as described above are pulverized and mixed, and then dried, or a lithium method is used. And a transition metal source compound or the like as described above are dispersed and pulverized and mixed in a medium such as water, or a lithium source compound and the transition metal source compound or the like as described above are pulverized and then dispersed in a medium such as water. There is a method such as a wet method in which the mixed and mixed slurry is dried by spray drying or the like and then baked, but the obtained composite oxide powder can be formed into a spherical shape, and a powder having a high bulk density can be obtained. The latter wet method is considered to be superior because it is easy.

However, according to the study by the present inventors, the conventionally known layered lithium nickel manganese composite oxide is a spinel type composite oxide or the like even if it is a composite oxide produced by the wet method. In comparison, the bulk density of the powder is low, so when used as a positive electrode active material in the positive electrode, the battery must be upsized in order to secure a certain energy capacity, and the battery must be downsized. Then, it was found that there was a problem that only low energy capacity was obtained.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems in the layered lithium nickel manganese composite oxide powder as the prior art. Therefore, the present invention provides a high bulk density. An object of the present invention is to provide a method for producing a layered lithium nickel manganese composite oxide powder that has and is suitable for use as a positive electrode active material of a lithium secondary battery.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by further pulverizing a layered lithium nickel manganese composite oxide powder. Therefore, according to the present invention, at least a lithium source compound, a nickel source compound and a manganese source compound, which have been ground and mixed, are mixed with nickel atom [Ni] and manganese atom [Mn].
And a slurry containing it in a molar ratio [Ni / Mn] of 0.7 to 9.0 by spray drying and firing to form a layered lithium nickel manganese composite oxide powder. The gist is a method for producing a layered lithium nickel manganese composite oxide powder by pulverizing the composite oxide powder.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, first, a slurry containing at least a lithium source compound, a nickel source compound and a manganese source compound, which has been ground and mixed, is dried by spray drying and then calcined to form a layered lithium. Made of nickel manganese composite oxide powder.

Here, the lithium source compound, the nickel source compound, and the manganese source compound include lithium, nickel, and manganese oxides, hydroxides, carbonates, nitrates, sulfates, oxalates, and carboxylates. , Alkylated,
Halides and the like can be mentioned, and among these, consideration is given to dispersion or solubility in a medium during slurry formation, reactivity to a composite oxide, and non-generation of NO _x , SO _x, etc. during firing. Selected.

Specific examples of the lithium source compound include Li ₂ O, LiOH, LiOH.H ₂ O,
Li ₂ CO ₃ , LiNO ₃ , LiOCOCH ₃ , Li ₃
(OCOC) ₃ H ₄ OH (lithium citrate), LiC
H ₃ , LiC ₂ H ₅ , LiCl, LiI and the like can be mentioned,
Among them, LiOH.H ₂ O, Li ₂ CO ₃ , LiNO ₃ ,
LiCH ₃ CO ₂ is preferable, and LiOH.H ₂ O is particularly preferable.

Specific examples of the nickel source compound include
Is, for example, NiO, Ni (OH) ₂, NiOOH, N
iCO₃・ 2Ni (OH)₂・ 4H₂O, Ni (N
O₃)₂・ 6H₂O, NiSO_Four, NiSO_Four・ 6H₂
O, Ni (OCO)₂・ 2H₂O, Ni (OCOCH
₃)₂, NiCl₂Etc., among them, NiO, Ni
(OH)₂, NiOOH, NiCO₃・ 2Ni (OH)
₂・ 4H₂O, NiC₂O _Four・ 2H₂O is preferred, N
iO, Ni (OH)₂, NiOOH are particularly preferred.

Specific examples of the manganese source include
For example, MnO₂, Mn₂O₃, Mn ₃O_Four, MnOO
H, MnCO₃, Mn (NO₃)₂, MnSO_Four, Mn
(OCOCH₃)₂, Mn (OCOCH₃)₃, MnC
l₂, MnCi₃And the like, among which MnO₂, Mn
₂O₃, Mn₃O_Four, MnOOH is preferable, and Mn
O₂, Mn₂O₃, Mn₃O_FourIs particularly preferable.

In the present invention, the lithium source compound, the nickel source compound, and the manganese source compound are dissociated into cations and anions in the slurry medium, as well as when they exist in the slurry medium in the form of compounds. , Lithium cations, nickel cations, or manganese cations are also included.

Further, in the present invention, the slurry containing the lithium source compound, the nickel source compound and the manganese source compound, in addition to these compounds, a magnesium source compound, an aluminum source compound, a calcium source compound, iron. It may further contain any compound selected from the group consisting of the source compound and the cobalt source compound.

Here, the magnesium source compound, the aluminum source compound, the calcium source compound, the iron source compound, and the cobalt source compound include magnesium oxide, aluminum oxide, calcium oxide, iron oxide, cobalt oxide, hydroxide, and carbonate. , Nitrates, sulfates, oxalates, tungstates, carboxylates, alkylated compounds, halogenated compounds, carbides, and the like. Among these, dispersion or solubility in a medium in slurry formation, to complex oxides Reactivity of
Also, it is selected in consideration of non-generation of NO _x , SO _{x and the} like during firing.

Specific examples of the magnesium source compound include MgO, Mg (OH) ₂ and Mg (NO).
_{3) 2 · 6H 2 O,} MgSO 4, Mg (OCO) 2 · 2
_{H 2 O, Mg (OCOCH 3} ) 2 · 4H 2 O, MgCl
_{2, and the} like, of which, MgO and Mg (OH) ₂ are preferable, and Mg (OH) ₂ is particularly preferable.

Specific examples of the aluminum source compound include Al ₂ O ₃ , Al (OH) ₃ and AlO.
_{OH, Al (NO 3) 3} · 9H 2 O, Ai 2 (SO 4)
₃ , AlCl _{3 and the} like, among which Al ₂ O ₃ , Al
(OH) ₃ and AlOOH are preferable, and AlOOH is particularly preferable.

Specific examples of the calcium source compound include CaO, Ca (OH) ₂ , CaCO ₃ , and
_{Ca (NO 3) 2 · 4H} 2 O, CaSO 4 · 2H 2 O,
Ca (OCO) ₂ · H ₂ O, CaWO ₄ , Ca (OCO
_{CH 3) 2 · H 2 O} , CaCl 2, CaC 2 , and the like, in, CaO, Ca (OH) are preferred _{2, CaCO 3, Ca (OH} ) 2 is particularly preferred.

Specific examples of the iron source compound include:
For example, Fe₂O₃, Fe₃O_Four, FeOOH, Fe (N
O₃)₃・ 9H₂O, FeSO_Four・ 7H₂O, Fe
₂(SO _Four)₃・ NH₂O, Fe (OCO)₂・ 2H₂
O, FeCl₂, FeCl₃Etc., among which, Fe
₂O₃, Fe₃O_Four, FeOOH is preferable, and Fe₂O
₃, FeOOH are particularly preferred.

Specific examples of the cobalt source compound include CoO, Co ₂ O ₃ , Co ₃ O ₄ and Co.
_{(OH) 2, Co (NO} 3) 2 · 6H 2 O, Co (SO
_{4) 2 · 7H 2 0,} Co (OCOCH 3) 2 · 4H
₂ O, CoCl _2, etc., among which CoO, Co ₂
O ₃ , Co ₃ O ₄ , and Co (OH) ₂ are preferable, and Co
(OH) ₂ is particularly preferred.

Among the magnesium source compound, aluminum source compound, calcium source compound, iron source compound, and cobalt source compound, the magnesium source compound, aluminum source compound, and cobalt source compound are preferable, and the aluminum source compound and cobalt source compound are preferable. Compounds are particularly preferred.
Further, also as each of these compounds, except when present in the slurry medium in the form of a compound, dissociates into cations and anions in the slurry medium, magnesium cations, aluminum cations, calcium cations, iron cations,
Alternatively, the case where it exists as a cobalt cation is also included.

In the present invention, at least the lithium source compound, the nickel source compound, and the manganese source compound are contained, and if necessary, the magnesium source compound, the aluminum source compound, the calcium source compound, the iron source compound,
And a slurry containing any compound selected from the group consisting of cobalt source compounds, the compounds are added to a medium such as water, and the mixture is pulverized and mixed using a wet pulverizer such as a medium agitation pulverizer. Alternatively, these compounds are prepared by pulverizing with a dry pulverizer such as a hammer mill, a roll mill, a ball mill and a jet mill, and then adding them into a medium such as water and mixing them. The former method of grinding and mixing in a medium is preferable because a uniform slurry is obtained.

In the present invention, the slurry contains the nickel source compound and the manganese source compound in a molar ratio [Ni / Mn] of nickel atom [Ni] and manganese atom [Mn] of 0.7 to. The Ni / Mn content is required to be in the range of 9.0, preferably 0.8 to 1.2 as Ni / Mn, more preferably 0.9 to 1.1, and A range of 0.95 to 1.05 is particularly preferable. When the value of Ni / Mn is less than the above range,
It becomes difficult to synthesize the layered lithium-nickel-manganese composite oxide in a single phase. On the other hand, if it exceeds the above range, it is economically disadvantageous.

The solid content concentration of the whole compound in the slurry at that time is usually 10% by weight or more, preferably in order to secure the powder particle size formed by spray drying described later in an optimum range. It is 12.5% by weight or more, and usually 50% by weight or less, preferably 35% by weight or less in order to secure a uniform slurry.

The average particle size of each compound in the slurry can be controlled by the above-described pulverizing and mixing method and the conditions thereof, but as a value measured by a laser diffraction / scattering type particle size distribution measuring device, calcination described later is carried out. In order to secure the reactivity and high bulk density in
It is preferably 1 μm or less, more preferably 0.5 μm or less, and from the viewpoint of economy, it is usually 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm.
That is all.

The viscosity of the slurry is usually 50 mPa · sec or more, preferably 50 mPa · sec or more, as a value measured by a BM type viscometer in order to secure the powder particle diameter formed by spray drying described later in an optimum range. Is 100 mPa · sec or more, more preferably 200 mPa · sec or more, and in order to ensure the handleability of the slurry, it is usually 3000 mPa · sec.
Seconds or less, preferably 2000 mPa · sec or less, more preferably 1600 mPa · sec or less.

In the present invention, the slurry containing at least the lithium source compound, the nickel source compound, and the manganese source compound, which have been crushed and mixed, is dried by spray drying and fired to form a layered lithium nickel manganese composite oxide. Eat with powder.

Here, spray drying is a known drying method in which the slurry is formed into droplets, sprayed and dispersed in a heated gas stream, and rapidly dried while being conveyed by the gas stream to obtain a powder. There are, for example, a rotary atomizer, a two-fluid nozzle type or a four-fluid nozzle type spray dryer, and the like. Air, nitrogen or the like is used as the pressurized gas for forming the liquid droplets, and the gas linear velocity is usually 100 m / sec or more, preferably 200 m
/ Sec or more, more preferably 300 m / sec or more, and usually 1000 m / sec or less. The heated gas flow is usually 50 ° C. or higher, preferably 70 ° C. or higher, and usually 120 ° C. or lower, preferably 100 ° C. or lower.

By this spray drying, a spherical powder as a pulverized mixture of the above compounds is obtained. The average particle diameter of the powder can be controlled by the above-mentioned spraying method, nozzle shape, pressurized gas injection rate, slurry supply rate, heated gas flow temperature, etc., but with a laser diffraction / scattering particle size distribution measuring device. The measured value is preferably 50μ
m or less, more preferably 30 μm or less, usually 4 μm
Or more, preferably 5 μm or more.

The powder obtained by the spray drying is, for example, in an apparatus such as a box furnace, a tubular furnace, a tunnel furnace, and a rotary kiln under an oxygen-containing gas such as air or an oxygen gas atmosphere, or nitrogen, argon. In an inert gas atmosphere such as
Preferably, heat treatment and firing are performed in an oxygen-containing gas or oxygen gas atmosphere.

The firing temperature at that time is usually 200 ° C. or higher, preferably 600 ° C. or higher, more preferably 800 ° C. or higher in order to secure reactivity, and a layered composite oxide having no defects is formed. Above, usually 1050 ℃ or less,
The temperature is preferably 1000 ° C. or lower, more preferably 950 ° C. or lower, and the heating time at that time is 0.5 to 5
It is preferable that the heating time is about 0 hours, and after the heat treatment, the material is gradually cooled at a rate of 5 ° C./minute or less.

In the method for producing the layered lithium nickel manganese composite oxide powder of the present invention, the slurry containing at least the lithium source compound, the nickel source compound, and the manganese source compound pulverized and mixed as described above is used. It is indispensable that the layered lithium-nickel-manganese composite oxide powder is obtained by drying by spray drying and firing, and then pulverizing the composite oxide powder.

Here, the pulverization is basically the same as in the production of the layered lithium nickel manganese composite oxide powder, and the complex oxide powder is added to a medium such as water, and the wet pulverizer is used. It is carried out by wet pulverizing with a dry powder, or by dry pulverizing the composite oxide powder with a dry pulverizer. The former wet pulverizing method gives a uniform spherical powder. It is preferable above. In the case of the former wet pulverization, drying is performed in the same manner as in the production of the layered lithium nickel manganese composite oxide powder,
Preferably by spray drying. In the latter case of dry pulverization, it is preferable to subject the pulverized powder to spherical treatment.

Further, the pulverized composite oxide is preferably subjected to a heat treatment in order to secure the mechanical strength of the powder,
As the heat treatment method, it is basically preferable to adopt the same method as the firing in the production of the layered lithium nickel manganese composite oxide powder. The heating temperature at that time is usually 700 ° C. or higher, preferably 750 ° C.
Or higher, more preferably 800 ° C. or higher, usually 1050
℃ or less, preferably 1000 ℃ or less, more preferably 9
It shall be 50 ° C or lower.

The layered lithium nickel manganese composite oxide produced by the method for producing a layered lithium nickel manganese composite oxide powder of the present invention is preferably a composite oxide represented by the following general formula (I).

[0036]

Embedded image Li _x Ni _y Mn _z Q _(1-YZ) O ₂ (I)

[In the formula (I), x is a number of 0 <x ≦ 1.2, and y and z are 0.7 ≦ y / z ≦ 9.
0 and a number satisfying the relationship of 0 ≦ 1-yz ≦ 0.5, and Q represents any metal atom selected from the group consisting of Mg, Al, Ca, Fe, and Co. . ]

In the above formula (I), it is preferable that 0 <x ≦ 1.1. If x exceeds the above range, the crystal structure of the layered composite oxide becomes unstable, and the battery capacity when used in a battery. Will tend to cause a decrease in Also, 0.8
≦ y / z ≦ 1.2 is preferable, and 0.9 ≦ y / z
≦ 1.1 is more preferable, and 0.95 ≦ y / z ≦
1.05 is particularly preferable. If y / z is less than the above range, it tends to be difficult to obtain a layered composite oxide in a single phase, while if it exceeds the above range, it is disadvantageous in terms of economy. Moreover, it is preferable that 0 ≦ 1-yz ≦ 0.35, and it is further preferable that 0 ≦ 1-yz ≦ 0.25. If 1-yz exceeds the above range, the battery capacity tends to decrease when used in a battery.

The layered lithium nickel manganese composite oxide powder produced by the method for producing a layered lithium nickel manganese composite oxide powder of the present invention has an average primary particle as a value measured by a laser diffraction / scattering particle size distribution analyzer. The diameter is usually 0.01 μm or more, preferably 0.02 μm
Or more, more preferably 0.1 μm or more, usually 30
μm or less, preferably 5 μm or less, more preferably 25
It is less than μm. The average secondary particle size is usually 1
μm or more, preferably 4 μm or more, usually 50 μm
The thickness is preferably 40 μm or less. Also BE
The specific surface area by T method, usually 0.1 m ² / g or more, preferably 4.0 m ² / g or more and usually 10.0 m ² /
g or less, preferably 8.0 m ² / g or less.

The layered lithium nickel manganese composite oxide powder produced by the method for producing a layered lithium nickel manganese composite oxide powder of the present invention has a powder packing density of 2
The tap density after being tapped 00 times is usually 0.5 g / cc or more, preferably 0.6 g / cc or more, more preferably 0.8 g / cc or more, and usually 3.0 g / cc or less,
Preferably less than 2.5 g / cc, and
The ratio of the tap density to the tap density before pulverization is preferably 1.10 or more, more preferably 1.15 or more, which shows a remarkable improvement effect in bulk density. Incidentally, the larger this ratio, the more remarkable the improvement effect,
Practically 10 or less, particularly 5 or less.

Since the layered lithium nickel manganese composite oxide powder according to the method for producing the layered lithium nickel manganese composite oxide powder of the present invention has a high bulk density,
It is suitable for use as a positive electrode active material of a lithium secondary battery.

The method of using the layered lithium nickel manganese composite oxide powder obtained by the production method of the present invention as a positive electrode active material of a lithium secondary battery is a conventionally known method. That is, the layered lithium nickel manganese composite oxide powder of the present invention as a positive electrode active material was made into a coating solution in which a conductive agent was optionally added together with a binder and dispersed in a solvent, and the coating solution was collected. After being applied to the surface of the current collector and dried, a positive electrode active material-containing layer is formed on the surface of the current collector by preferably performing a consolidation treatment by a uniaxial press, a roll press, or the like, to obtain a positive electrode.

Examples of the binder used here include resins such as polyvinylidene fluoride, polytetrafluoroethylene, polymethylmethacrylate and polyethylene, styrene butadiene rubber, acrylonitrile butadiene rubber, ethylene propylene rubber, fluorine rubber and the like. Rubber, other polymeric substances such as polyvinyl acetate and cellulose, and examples of the conductive agent include graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke. The carbonaceous fine particles may be mentioned, respectively, and as the solvent, for example, ether solvents such as ethylene oxide and tetrahydrofuran, ketone solvents such as methyl ethyl ketone and cyclohexanone, ester solvents such as methyl acetate and methyl acrylate, and diethyl ether. Amine, N, N- amine solvents dimethylaminopropylamine and the like, N- methylpyrrolidone, dimethylformamide, an aprotic polar solvent such as dimethylacetamide.

The current collector is usually made of aluminum, stainless steel, nickel-plated steel or the like and has a thickness of 1 to 1.
A foil having a thickness of 000 μm, preferably 5 to 500 μm can be mentioned, and an aluminum foil is preferable as a collector for the positive electrode.
The thickness of the positive electrode active material-containing layer is usually 1 to 1000 μm.
m, preferably 10 to 200 μm.

In addition, the content ratio of the positive electrode active material in the positive electrode active material containing layer is determined in order to secure battery characteristics such as battery capacity.
Usually 10 wt% or more, preferably 30 wt% or more, more preferably 50 wt% or more, usually 99.9 wt% or less, preferably 99 wt% or less in order to secure the mechanical strength and the like of the electrode, More preferably, it is 95% by weight or less. Further, the content ratio of the binder is usually 0.1% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more in order to secure the mechanical strength and the like of the electrode. In order to secure battery characteristics such as conductivity, it is usually 80
The content is not more than 60% by weight, preferably not more than 60% by weight, more preferably not more than 40% by weight. The content ratio of the conductive agent is usually 0.01% by weight in order to secure battery characteristics such as conductivity.
Or more, preferably 0.1% by weight or more, more preferably 1
In order to secure battery characteristics such as battery capacity, the content is usually 50% by weight or less, preferably 30% by weight or less,
It is more preferably 15% by weight or less.

The negative electrode is a coating liquid in which the negative electrode active material is dispersed in a solvent together with a binder, and the coating liquid is applied to the surface of the current collector and dried, and preferably uniaxial press or roll. By performing a consolidation treatment with a press or the like, a negative electrode active material-containing layer is formed on the surface of the current collector to obtain a negative electrode.

As the negative electrode active material used here,
For example, lithium, lithium aluminum alloy, graphite,
Coal and petroleum coke carbides, coal and petroleum
Ji carbide, needle coke, pitch coke, feather
Carbides such as knoll resin and crystalline cellulose, furnace
Carbon black such as rack and acetylene black, and
, SnO, SnO₂, Sn_1-xM_xO (M is Hg,
P, B, Si, Ge, or Sb, and x is 0 ≦ x <1
Is. ), Sn₃O₂(OH)₂, Sn_3-xM _xO₂
(OH)₂(M is Mg, P, B, Si, Ge, Sb, or
Is Mn and x is 0 ≦ x <3. ), LiSiO
₂, SiO₂, LiSnO₂Etc., and also binding
The same agents and solvents as those used for forming the positive electrode are listed.
You can The current collectors are copper, nickel, stainless steel.
Foils such as stainless steel, nickel-plated steel, etc.
Copper foil is preferable as the electric body.

Then, a positive electrode having a positive electrode active material-containing layer on the surface of the current collector, a negative electrode having a negative electrode active material-containing layer on the surface of the current collector, an electrolyte layer, and if necessary, interposed between the positive electrode and the negative electrode. A lithium secondary battery is composed of the separator.

Here, as the electrolyte layer, for example, an organic electrolyte solution in which an electrolyte is dissolved in a solvent, a polymer solid electrolyte, a gel electrolyte, an inorganic solid electrolyte or the like is used, in which the organic electrolyte solution is preferable.

As the electrolyte in the organic electrolytic solution,
For example, LiCl, LiBr, LiClO_Four, LiAs
F₆, LiPF₆, LiBF_Four, LiB (C
₆H_Five)_Four, LiCH₃SO₃, LiCF₃SO₃, L
iN (SO₂CF₃)₂, LiN (SO ₂C
₂F_Five)₂, LiN (SO₃CF₃)₂, LiC (SO
₂CF₃)₃Etc., and as the solvent, for example,
For example, diethyl ether, 1,2-dimethoxyethane,
1,2-diethoxyethane, tetrahydrofuran, 2-
Methyl tetrahydrofuran, 1,4-dioxane, 1,
3-dioxolane, 4-methyl-1,3-dioxolane
Such as ethers, keto such as 4-methyl-2-pentanone
, Methyl formate, methyl acetate, methyl
Esters such as ropionate, dimethyl carbonate,
Diethyl carbonate, methyl ethyl carbonate,
Tylene carbonate, propylene carbonate, butyre
Carbonates such as vinyl carbonate and vinylene carbonate
, Γ-butyrolactone, γ-valerolactone, etc.
Halogenated carbonization of kutones and 1,2-dichloroethane
Hydrogen, sulfolane, sulfolane such as methylsulfolane
Compounds, acetonitrile, propionitrile, buty
Nito such as ronitrile, valeronitrile, and benzonitrile
Rills, diethylamine, ethylenediamine, trieta
Amines such as nolamine, trimethyl phosphate, phosphoric acid
Phosphoric acid esters such as triethyl, N, N-dimethylphosphine
Lumamide, N-methylpyrrolidone, dimethyl sulfoxide
An aprotic polar solvent such as side and the like can be mentioned.

As the separator, polyethylene,
A microporous film of a polymer such as polyolefin such as polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyester, polyamide, polysulfone, polyacrylonitrile, cellulose, cellulose acetate or the like is used.

[0052]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Comparative Example 1 Lithium hydroxide monohydrate [Li as a lithium source compound
OH.H ₂ O], nickel hydroxide [Ni (OH) ₂ ] as a nickel source compound, and manganese trioxide [Mn ₂ O ₃ ] as a manganese source compound, which are finally obtained. The molar ratio of each atom in the manganese composite oxide is lithium atom [Li]: nickel atom [Ni]: manganese atom [Mn] = 1.05: 0.5.
Add 0: 0.50 to pure water to obtain a solid content of 1
A 2.5 wt% slurry was prepared, and this slurry was mixed using a circulating medium stirring type wet pulverizer (“Dyno Mill KD-20B type” manufactured by Shinmaru Enterprises Co., Ltd.), and each compound in the slurry was mixed. Wet pulverization was carried out for about 6 hours until the average particle diameter of was 0.3 μm as a value measured by a laser diffraction / scattering type particle size distribution measuring device.
The viscosity of this slurry was 290 mPa · sec as a value measured by a BM type viscometer.

Then, the obtained slurry was heated to 90 ° C. by using a spray dryer (“Four-fluid nozzle type spray dryer” manufactured by Fujisaki Electric Co., Ltd.) at a downflow rate of 23 m ³ / min. On the other hand, in the orthogonal direction, it is jetted from the nozzle by a pressurized air at a linear velocity of 300 m / sec, dried by spray drying, and then the obtained powder particles are fired in air at 900 ° C. for 10 hours, In molar ratio, lithium atom [Li]: nickel atom [Ni]:
Manganese atom [Mn] = 1.05: 0.50: 0.50
A layered lithium nickel manganese composite oxide powder was produced.

The layered lithium nickel manganese composite oxide powder obtained is a particle having a substantially spherical shape, and is powder X
When the line diffraction was measured, it was confirmed to be a rhombohedral layered lithium nickel manganese composite oxide. or,
Fully automatic powder specific surface area measuring device (Okura Riken "AMS80
The specific surface area measured by the BET method was 6.14 m ² / g. Further, about 5 g of the obtained composite oxide powder was put into a 10 ml glass graduated cylinder, and the powder packing density after tapping 200 times was measured as the tap density, and it was 1.12 g / cc.

Example 1 The layered lithium nickel manganese composite oxide powder obtained in Comparative Example 1 was added to pure water to prepare a slurry having a solid content concentration of 23.0% by weight, and this slurry was agitated with a circulating medium. Wet milling was performed for about 2 hours using a mold wet mill (“Dyno Mill KDL-A type” manufactured by Shinmaru Enterprises Co., Ltd.). Next, the obtained slurry was down-flowed with a spray dryer (“Two-fluid nozzle type spray dryer” manufactured by Okawara Kakoki Co., Ltd.) at a flow rate of 3 m ³ / min to a heated air flow of 90 ° C. The powder particles were ejected from the nozzle in a perpendicular direction at a linear velocity of 200 m / sec by a pressurized air, dried by spray drying, and then the obtained powder particles were heat-treated in air at 900 ° C. for 10 hours to give a A layered lithium nickel manganese composite oxide powder having a ratio of lithium atom [Li]: nickel atom [Ni]: manganese atom [Mn] = 1.05: 0.50: 0.50 was produced.

The layered lithium nickel manganese composite oxide powder obtained is a particle having a substantially spherical shape, and is powder X
When the line diffraction was measured, it was confirmed to be a rhombohedral layered lithium nickel manganese composite oxide. or,
The average secondary particle diameter measured by a laser diffraction / scattering type particle size distribution analyzer was 7.2 μm.

In addition, a comparison table was prepared in the same manner as in Comparative Example 1.
When the area was measured, it was 5.54 m ²/ G.
In addition, about 5 g of the obtained composite oxide powder is mixed with 10 ml of glass.
Powder in a stainless steel graduated cylinder and tapped 200 times
When the body packing density was measured as the tap density, it was 1.4.
0 g / cc, which is the tap density before grinding in Comparative Example 1.
The ratio to degree was 1.25.

Application Example The layered lithium nickel manganese composite oxide powder obtained in Comparative Example 1 and Example 1, acetylene black as a conductive agent, and polytetrafluoroethylene powder as a binder, % By weight: 20% by weight: 5% by weight and mixed into an amount of about 8 mg when punched into a circle having a diameter of 9 mm to form a sheet, and the sheet was made into a circle having a diameter of 9 mm. A positive electrode was produced by punching and crimping to one surface of an expanded metal made of aluminum. A coin cell was assembled with this positive electrode as the test electrode and lithium metal as the counter electrode, and the current density was 0.2 m.
A / cm ² constant current charging, that is, a reaction for releasing lithium ions from the positive electrode is performed at an upper limit of 4.3 V, and then constant current discharging with a current density of 0.2 mA / cm ² , that is, a reaction for occluding lithium ions in the positive electrode. Charging at a lower limit of 3.0 V, the initial charge capacity [Qs per unit weight of the positive electrode active material]
(C) (mAh / g)] and initial discharge capacity [Qs
(D) (mAh / g)] was measured. The initial discharge capacity [Qs (D) (mAh / g)] was set to a current density of 11 mA /
discharge capacity measured in cm ² [Qa (D) (mAh /
g)] and the results are shown in Table 1.

Also, their initial discharge capacity [Qs (D)
(MAh / g)], and discharge capacity [Qa (D) (mAh
/ G)] is converted from the tap density per unit volume to obtain an initial discharge capacity [Qs' (D) (mAh / cc)],
And discharge capacity [Qa '(D) (mAh / cc)] are also shown in Table 1.

On the other hand, graphite powder (d
₀₀₂ = 3.35Å, average particle size = 8 to 10 μm), and polyvinylidene fluoride as a binder was dispersed in N-methylpyrrolidone in an amount of 92.5% by weight: 7.5% by weight. A slurry was prepared by applying the slurry to one surface of a copper foil having a thickness of 20 μm, and after drying, it was punched into a circle having a diameter of 12 mm and pressed at 0.5 ton / cm ² to produce a negative electrode. A unit weight of the negative electrode active material when a coin cell was assembled using the negative electrode as a test electrode and lithium metal as a counter electrode, and a reaction of occluding lithium ions in the negative electrode at a constant current of 0.2 mA / cm ² was performed at a lower limit of 0 V. Initial storage capacity [Qf (mAh /
g)] was measured.

Subsequently, on the positive electrode can, a positive electrode prepared by pressing a circular sheet having a diameter of 12 mm (weight of about 18 mg) punched from the positive electrode sheet to an expanded metal made of aluminum was placed, and Porous polyethylene film (thickness 25
μm), and then press it with a polypropylene gasket, place the negative electrode prepared above, and then place a spacer for adjusting the thickness, and then mix ethylene carbonate and diethyl carbonate as a non-aqueous electrolyte. A solution prepared by dissolving 1 mol / liter of lithium hexafluorophosphate (LiPF ₆ ) in a solvent (volume ratio 3: 7) was added to the inside of the battery so that the solution was sufficiently impregnated, and then the negative electrode can was placed and sealed. By doing so, a coin cell was produced. At that time, positive electrode active material weight (g) / negative electrode active material weight (g) = {[Qf (mA
h / g)] / 1.2} / [Qs (C) (mAh / g)]
It was set so that

With respect to the obtained coin cell, 1-hour rate current value [1C (mA)] = [Qs (D) (mAh / g)]
X positive electrode active material weight (g), first, at room temperature, a constant current 0.2C charge / discharge 2 cycle, and a constant current 1C charge / discharge 1 cycle test, and then at 50 ° C, constant current 0. 1 cycle of 2C charge / discharge and 50 charge / discharge of constant current 1C
The cycle was tested. The charging upper limit voltage is 4.2.
V and the lower limit voltage were 3.0V. At this time, in a constant current 1C charge / discharge 50 cycle test at 50 ° C., the first cycle discharge capacity [Qh (1) (mAh / g)] and the 50th cycle discharge capacity [Qh (50) (mAh / g)] Was measured, the high temperature cycle capacity retention rate [P (%)] was calculated from these values according to the following formula, and the results are shown in Table 1. P (%) = {[Qh (50)] / [Qh (1)]} × 1
00

[0064]

[Table 1]

From the results of Comparative Example 1 and Example 1 described above, the layered lithium nickel manganese composite oxide powder of Example 1 obtained by the production method of the present invention was found to have a bulk density relative to the layered composite oxide of Comparative Example 1. Of the layered lithium nickel manganese composite oxide powder of Example 1 obtained by the production method of the present invention is positive electrode active material. The lithium secondary battery used as has the same battery characteristics per unit weight as compared with the case where the layered composite oxide of Comparative Example 1 is used as the positive electrode active material, and the battery characteristics by pulverization or further heat treatment are It is clear that the above deterioration has not occurred, and therefore it is clear that the battery characteristics per unit volume are excellent.

[0066]

According to the present invention, it is possible to provide a method for producing a layered lithium nickel manganese composite oxide powder having a high bulk density and suitable for use as a positive electrode active material of a lithium secondary battery. .

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Claims (7)

[Claims] 1. A ground and mixed at least lithium source compound, nickel source compound and manganese source compound,
A layered lithium nickel manganese manganese is obtained by drying a slurry containing a molar ratio [Ni / Mn] of nickel atoms [Ni] and manganese atoms [Mn] in the range of 0.7 to 9.0 by spray drying and firing. A method for producing a layered lithium nickel manganese composite oxide powder, which comprises pulverizing the composite oxide powder after forming the composite oxide powder. 2. The method for producing a layered lithium nickel manganese composite oxide powder according to claim 1, wherein the layered lithium nickel manganese composite oxide powder is pulverized by wet pulverization and then dried by spray drying. 3. The method for producing a layered lithium nickel manganese composite oxide powder according to claim 1, wherein the layered lithium nickel manganese composite oxide powder is pulverized and then heat-treated. 4. The layered lithium nickel manganese composite according to claim 1, wherein the pulverized layered lithium nickel manganese composite oxide powder is a composite oxide represented by the following general formula (I). Method for producing oxide powder. Embedded image Li _x Ni _y Mn _z Q _(1-YZ) O ₂ (I) [In the formula (I), x is a number satisfying 0 <x ≦ 1.2, and y and z are 0 respectively. 0.7 ≦ y / z ≦ 9.0 and 0 ≦
1 is a number satisfying the relation of 1-yz ≦ 0.5, and Q is M
Indicates any metal atom selected from the group consisting of g, Al, Ca, Fe, and Co. ] 5. The layered lithium nickel manganese composite oxide powder after pulverization has a specific surface area of 0.1 to 1 according to the BET method.
The method for producing the layered lithium nickel manganese composite oxide powder according to any one of claims 1 to 4, wherein the layered lithium nickel manganese composite oxide has a particle size of 0.0 m ² / g. 6. The layered lithium nickel manganese composite oxide powder after pulverization has a tap density of 0.5 to 3.0 g / cc.
The method for producing a layered lithium nickel manganese composite oxide powder according to any one of claims 1 to 5, wherein 7. The layered lithium nickel manganese composite oxide powder after crushing has a ratio of the tap density to the tap density before crushing of 1.10 or more.
5. The method for producing a layered lithium nickel manganese composite oxide powder according to any one of 1.