JP2003183022A - Method for producing lithium-transition metal complex oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a lithium-transition metal complex oxide suitable for a positive electrode active material of a lithium ion secondary battery, particularly for mass-producing the lithium-transition metal complex oxide capable of charging/discharging at a high current density at a low price. <P>SOLUTION: The method for producing the lithium-transition metal complex oxide comprises spray drying a slurry containing a lithium source and a transition metal source using a four-stream nozzle and subjecting the resultant material to burning treatment, or spray drying a slurry containing the transition metal source using the four-stream nozzle before the resultant material is mixed with the lithium source and then subjecting them to the burning treatment. The method for producing the lithium-transition metal complex oxide having a median diameter of 14 μm or less is characterized by a slurry concentration of 1-40 wt.% and the ratio of a supply volume of the slurry for the spray by the four-stream nozzle to a supply volume of a gas stream of 1,500 or more in the supply volume of the gas stream/the supply volume of the slurry. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a lithium transition metal composite oxide and a lithium ion secondary battery using the same as an active material.

[0002]

_2. Description of the Related Art As positive electrode active materials for lithium-ion secondary batteries, layered composite oxides such as LiCoO ₂ type and LiNiO ₂ type and LiMn ₂ O ₄ type compounds having a spinel structure have high voltage of 4V class. It has already been put into widespread practical use, or is in the stage of practical use, since it has a high energy density.

On the other hand, the positive electrode active material is usually mixed with a conductive material and a binder to form a positive electrode mixture. The higher the packing density of the positive electrode active material is, the higher the energy density per unit volume is. When the battery of the above is manufactured, a high capacity battery is obtained, and if the battery has the same energy capacity,
There are advantages such as downsizing. In view of this, a method of granulating the positive electrode active material particles into a spherical shape to improve the filling property has been proposed. For example, a method of spray drying a slurry as a raw material, a method of spray pyrolyzing a solution as a raw material, and the like are known.

On the other hand, in fields such as electric vehicle applications where charging and discharging at high current densities are required, it is preferable to make the positive electrode mixture layer as thin as possible, and the active material particles used for such applications are From the viewpoint of the uniformity of the coating film, it is necessary to make the particles smaller. In fields where charging and discharging at high current densities are required, median type lithium-transition metal composite oxides of 14 μm or less are particularly required.

[0005]

However, it is difficult to form particles having a small particle size by spraying. In particular, when the median diameter is in the range of 14 μm or less, there is a problem in the conventional droplet atomizing method (rotary atomizer method, two-fluid nozzle method) in spray drying. That is, in the rotary atomizer method, it is necessary to make the solid content concentration extremely low, and in the two-fluid nozzle method, the nozzle 1
Since the productivity per bottle is low, the number of nozzles is increased and the apparatus becomes large, so that it is not always sufficient in terms of industrially low-cost production.

The present invention provides a method for producing a lithium transition metal composite oxide, which is suitable as a positive electrode active material for a lithium ion secondary battery, and in particular, a lithium transition metal composite oxide that can be charged and discharged at a high current density at low cost. The purpose is to provide a method for mass production.

[0007]

Means for Solving the Problems The inventors of the present invention have made extensive studies as to a method for mass-producing inexpensive lithium-transition metal composite oxides that can be charged and discharged at a high current density. As a result, a slurry for spray drying has been obtained. As a method for forming droplets, it has been found that it can be achieved by using a four-fluid nozzle, and furthermore, it is possible to control an extremely fine particle size by controlling the slurry concentration and the slurry supply amount / gas fluid supply amount. They have found that they can do so and have completed the present invention.

That is, the gist of the present invention resides in the following (1) to (13). (1) A slurry containing a lithium source and a transition metal source is spray-dried using a four-fluid nozzle, and this is subjected to firing treatment, or a slurry containing a transition metal source is sprayed using a four-fluid nozzle. In the method for producing a lithium-transition metal oxide, which is dried and then mixed with a lithium source for firing treatment, the slurry concentration is 1 to 40 wt%, and the slurry supply amount and gas-fluid in spraying with a four-fluid nozzle. The ratio of the amount of gas supplied is the amount of gas / fluid supplied / slurry supplied = 15
A method for producing a lithium-transition metal composite oxide having a median type of 14 μm or less, which is 00 or more.

(2) The transition metal source is at least Mn compound, Ni
The production method according to (1) above, which is a compound selected from the group consisting of a compound and a Co compound. (3) The production method according to (1) or (2) above, in which a slurry containing a lithium source and a transition metal source is spray-dried using a four-fluid nozzle and is then subjected to a firing treatment. (4) The production method according to any one of (1) to (3) above, wherein the nozzle gap of the slurry supply unit of the four-fluid nozzle is 0.1 to 1.0 mm.

(5) The injection velocity of the gas flow is 100 to 1 linear velocity of gas.
The production method according to any one of (1) to (4) above, which is 000 m / s. (6) The production method according to any of (1) to (5) above, wherein the solid particles in the slurry have an average particle size of 2 μm or less. (7) The slurry is B, Al, Ti, V, Cr, Fe, Sn, Cu, Zn,
The above containing at least one metal element selected from the group consisting of Mg, Ga, Zr, Bi, Ge, Nb, Ta, Be, Ca and Sc.
The manufacturing method according to any one of (1) to (5).

(8) The metal element source is B, Al, Ti, V, Cr, F
e, Sn, Cu, Zn, Mg, Ga, Zr, Bi, Ge, Nb, Ta, Be, Ca
And an element selected from the group consisting of Sc, an oxide, a hydroxide, an oxyhydroxide, a nitrate, a sulfate, a carbonate, a dicarboxylate, a fatty acid salt and at least one selected from ammonium salts above (7 ) The manufacturing method described in. (9) The lithium source is Li ₂ CO ₃ , LiNO ₃ , LiOH, LiOH.H ₂ O,
Li ₂ O, Li acetate, Li dicarboxylic acid, Li citrate, Fat L
The method according to any one of (1) to (8) above, which is at least one selected from the group consisting of i, alkyllithium, and lithium halide.

(10) The transition metal source is Mn ₃ O ₄ , Mn ₂ O ₃ , Mn
O ₂ , MnCO ₃ , Mn (NO ₃ ) ₂ , MnSO ₄ , manganese acetate, manganese dicarboxylate, manganese citrate, fatty acid manganese,
Manganese oxyhydroxide, manganese hydroxide, manganese halide, nickel oxide, nickel hydroxide, nickel oxyhydroxide, at least one selected from the group consisting of nickel halide and nickel carbonate (1) ~ The production method according to any one of (9).

(11) The method according to any one of (1) to (10) above, wherein the lithium-transition metal composite oxide is represented by the following general formula (I).

[0014]

## STR2 ## _{Li 1 + x Mn 2-xy} M y O 4 + δ ··· (I) ( here, x is the number of -0.1~0.1, y is the number of 0 to 0.3, M is B, A
l, Ti, V, Cr, Fe, Sn, Cu, Zn, Mg, Ga, Zr, Bi, Ge,
At least one element selected from the group consisting of Nb, Ta, Be, Ca, and Sc, δ represents a number of -0.1 to 0.1) (12) The above (1) to (11) A method for producing an electrode, comprising applying a coating material containing a mixture of the lithium transition metal composite oxide obtained by the method and a binder, and a solvent onto a current collector and drying the coating material.

(13) A lithium secondary battery using the lithium transition metal composite oxide obtained by the method according to any one of (1) to (11) above as a positive electrode active material.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method for producing a lithium-transition metal composite oxide having a median diameter of 14 μm or less. In the present invention, the "lithium transition metal composite oxide having a median diameter of 14 µm or less" means "a lithium transition metal composite oxide having a median diameter of secondary particles of 14 µm or less".

Examples of the lithium transition metal composite oxide in the present invention include a lithium nickel composite oxide, a lithium cobalt composite oxide, a lithium manganese composite oxide and the like, and preferably a lithium manganese composite oxide or a lithium nickel composite oxide. It is an oxide. Examples of the lithium manganese composite oxide include lithium manganate having a spinel structure having LiMn ₂ O ₄ as a basic composition, and lithium manganate having a layered structure having a basic composition of LiMnO _2, which is typically used. Spinel type lithium manganate is preferable in terms of ease of use and cycle characteristics.

The lithium manganese composite oxide may further contain other elements in addition to lithium, manganese and oxygen. Other elements include B, Al, Ti, V, Cr,
Fe, Sn, Cu, Zn, Co, Ni, Mg, Ga, Zr, Bi, Ge, Nb, T
Metal elements such as a, Be, Ca, Sc can be mentioned,
Preferably Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Mg, G
a and Zr, and Al is particularly preferable. Further, a part of oxygen atoms can be replaced with a halogen element such as fluorine.
These elements have a function of stabilizing the crystal structure by substituting a part of the manganese site.

The basic composition of the spinel type lithium manganese composite oxide is represented by the above general formula (I), and among them, the one represented by the following general formula (II) is preferable.

[0020]

Embedded image _{Li 1 + x 'Mn 2-} x'-y' M 'y' O 4 + δ '·· (II) ( wherein, x' is the number of -0.1~0.1, y 'is 0 Number of 0.3, M '
Is Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Mg, Ga and Zr
Represents at least one element selected from the group consisting of
δ'represents a number from -0.1 to 0.1. Further, the lithium-nickel composite oxide may further contain another element in addition to lithium, nickel and oxygen. Other elements include B, Al, Ti, V, Cr, Fe, Sn, C
u, Zn, Co, Mn, Mg, Ga, Zr, Bi, Ge, Nb, Ta, Be, C
Metal elements such as a and Sc can be mentioned, but Co and Al are preferable. That is, in a preferred embodiment, the lithium-nickel composite oxide is a composite oxide containing lithium, nickel and Co, or Al.

Such another element-substitution type lithium nickel composite oxide is usually used in the case of, for example, a lithium nickel composite oxide having a hexagonal layered rock salt structure.

[0022]

Embedded image Li _{x ″} Ni _{1-y ″} M ″ _{y ″} O _{2-δ ″} (where 0.8 ≦ x ″ ≦ 1.3, 0 <y ″ ≦ 0.5, and M ′ 'Is
B, Al, Ti, V, Cr, Fe, Sn, Cu, Zn, Co, Mn, Mg, Ga,
Zr, Bi, Ge, Nb, Ta, Be, Ca and Sc represent at least one element selected from the group consisting of, δ '' corresponds to oxygen deficiency or oxygen excess, -0.1 <δ ''<0.1 Can be represented by the composition).

In any of the above-mentioned lithium manganese composite oxide and lithium nickel composite oxide,
The type and composition ratio of the substituting element are not limited to these as long as the crystal structure can be stabilized.
In any of the above composition formulas, the case where the amount of oxygen has a non-stoichiometric ratio is included. Furthermore, in any of the above cases, it is possible to replace part of the sites of manganese atoms or nickel atoms with lithium by using, for example, a stoichiometric amount or more of lithium as a raw material.

In the present invention, the lithium-transition metal composite oxide is a slurry prepared by mixing at least a transition metal compound with a solvent, usually a slurry prepared by mixing a transition metal compound and a lithium compound with a solvent. It is manufactured by a method of drying and firing (hereinafter sometimes referred to as "spray dry method"). In addition, in the above-mentioned manufacturing method, in addition to the lithium compound and the transition metal compound, a compound containing a metal such as lithium (hereinafter sometimes referred to as "other metal") other than the transition metal is used as a transition metal compound or By mixing with a solvent together with a lithium compound, a lithium-transition metal composite oxide in which a part of the transition metal is replaced with another metal element can be obtained.

Lithium used as a raw material for slurry preparation
As an um compound, Li₂CO₃, LiNO ₃, LiOH, LiOH ・ H
₂O, Li₂O, Li acetate, Li dicarboxylic acid, Li citrate, Fat
Lithium halo such as acid Li, alkyl lithium, LiCl, LiI
Examples include genide compounds, which are used alone or in combination of two or more.
Can be Transition gold used as raw material for slurry preparation
Group compounds include manganese compounds, nickel compounds and cobalt compounds.
It is at least one selected from ruth compounds. manga
Compounds include Mn₂O₃, MnO₂Manganese oxide, such as M
nCO₃, Mn (NO₃)₂ , MnSO_Four, Manganese acetate, dicarboxylic acid
Manganese, manganese citrate, fatty acid manganese, etc.
Cancer salts, oxyhydroxides, halides, etc.
It Mn₂O₃As MnCO₃And MnO₂Heat treatment of compounds such as
You may use what was produced by.

As the nickel compound, nickel oxide such as NiO, nickel hydroxide such as Ni (OH) ₂ or NiOOH.
And oxyhydroxides such as NiCl ₂ , halides such as NiCl _{2 and} nickel carbonate such as NiCO ₃ . Examples of the compound of the other metal element used in combination with the transition metal compound include oxides, hydroxides, nitrates, carbonates, dicarboxylic acid salts, fatty acid salts, ammonium salts and the like.

These starting materials are mixed by wet mixing or dry mixing to obtain a slurry. A step of pulverization may be added after mixing or during mixing. Further, if desired, instead of preparing a slurry containing all the raw material compounds and subjecting it to spray drying, a slurry is prepared with a raw material compound other than the lithium compound, and this is spray dried, and the lithium compound is added to the obtained powder. It is also possible to add and use for firing.

As the dispersion medium of the slurry used in the present invention, various organic solvents and aqueous solvents can be used, but water is preferable. The average particle size of the solid matter in the slurry is usually 2 μm or less, preferably 1 μm or less, more preferably 0.5 μm or less. If the average particle size of the solid matter in the slurry is too large, the sphericity tends to decrease, and the final powder packing density tends to decrease. As a method for controlling the average particle diameter of the solid matter in the slurry, a raw material powder is previously dry-milled by a ball mill, a jet mill or the like, a method of dispersing this in a dispersion medium, a raw material powder is dispersed in the dispersion medium, and the medium is stirred. A method of wet crushing using a mold crusher and the like can be mentioned. Since it is not preferable to make the particles smaller than necessary because the cost of pulverization is increased, the average particle diameter of the solid is usually 0.01 μm or more, preferably 0.05 μm or more, and more preferably 0.1 μm or more.

In the above, when the transition metal compound is a manganese compound, the mixing ratio of the lithium compound and the transition metal compound in the slurry is usually Li / M in terms of Li atom and Mn atom.
n = 0.4-0.6, preferably 0.45-0.55, more preferably
It is 0.5 to 0.55. If there is too much Li or too little Li, a sufficient capacity cannot be obtained. When the lithium transition metal composite oxide is a lithium manganese composite oxide of other element substitution type, the atomic ratio of the metal elements other than manganese in the total of Mn atoms and metal atoms other than manganese (substitution element) is 2.5. % Or more, preferably 5% or more, usually 30% or less, preferably 20 mol% or less. If the amount of the metal element other than manganese is too small, the effect of improving the high temperature cycle may not be sufficient, and if it is too large, the capacity of the battery may decrease. In this case,
The atomic ratio of Li / Mn is Li atom / (Mn atom + substitution metal atom other than Mn). That is, usually Li atom / (Mn atom + substitution metal atom other than Mn) = 0.4 to 0.6, preferably 0.45 to 0.55, and more preferably 0.5 to 0.55.

When manganese is used as a transition metal, that is, when a lithium-manganese composite oxide is produced, a part of the manganese site of the lithium-manganese composite oxide is replaced with the above-mentioned other element to improve high temperature characteristics and safety. Etc. can be improved. The obtained slurry is subjected to spray drying. In the present invention, this spray drying is performed using a four-fluid nozzle. FIG. 1 is a schematic side view of a nozzle (four-fluid nozzle) portion of a spray dryer that can be used for spray drying in the present invention. FIG. 2 is an enlarged view of the nozzle tip of FIG. 3 is a schematic cross-sectional view showing the flow of FIG. In the cylindrical nozzle 1, a nozzle tip 3 having a smooth inclined surface 2 is provided in an annular shape around the cylinder. A gas outlet 4 for supplying a high-speed gas flow flowing along the inclined surface 2 through a gas supply pipe 7 is provided at the nozzle tip 3 toward the inclined surface 2. A slurry outlet 5 for supplying the slurry through the slurry supply pipe 8 is provided at the nozzle tip 3 so that the discharged slurry intersects the flow direction of the gas flow discharged along the inclined surface. ing. The gas flow G emitted from the gas outlet 4 flows at high speed in parallel with the inclined surface along the inclined surface. On the other hand, the slurry ejected from the slurry ejection port 5 so as to intersect with the flow direction of the gas flow G is pressed against the inclined surface by the gas flow flowing at high speed to become the thin film flow S. The thin film flow S flowing along the inclined surface normally flows at supersonic speed and leaves the inclined surface at the nozzle edge 6, and at the same time, becomes a droplet and is sprayed in a predetermined direction. These droplets collide with the other thin film flow S ′ and become smaller droplets.
In FIG. 1, since the nozzle edge is provided in a ring shape around the nozzle, droplets are similarly sprayed in a ring shape. By spraying in an annular shape, the spray amount can be increased, that is, the production amount can be increased. It is preferable that the spraying direction is substantially horizontal because the nozzle can be easily designed. The term “generally horizontal” means a width of about ± 40 ° with respect to the horizontal.

Air, nitrogen or the like can be used as the gas supplied as the gas flow, and air is usually used. It is preferable to use these under pressure. Gas flow, as a linear velocity of gas, usually 100 m / s or more, preferably 200 m
/ s or more, more preferably 300 m / s or more. If the linear velocity is too low, it becomes difficult to form appropriate droplets, but it is difficult to obtain a high linear velocity, so the normal ejection velocity is 1000 m / s or less.

In the present invention, the slurry concentration is from 1 to 40.
Must be wt%. Here, the slurry concentration is 1
The term "wt% or more" means that the slurry concentration is not substantially 0 wt%. If the slurry concentration is too low, the productivity will be low, and if it is too high, the viscosity of the slurry will be high and spraying with a four-fluid nozzle will not be possible. The slurry concentration is preferably 5 wt% or more, more preferably 10 wt% or more, particularly preferably 20 wt% or more, preferably 35 wt%
% Or less, more preferably 30 wt% or less.

Further, in the present invention, it is essential that the ratio of the supply amount of the slurry and the supply amount of the gas fluid in spraying by the four-fluid nozzle is equal to or more than the supply amount of the gas fluid / the supply amount of the slurry = 1500. If this value is too low, the particle size becomes large. There is no particular upper limit on the value of gas / slurry supply / slurry supply in order to create a small particle size, but increasing this value increases the gas / fluid supply, and in order to do so, the size of the compressor must be large. Is required, and the manufacturing equipment is too expensive. In addition, increasing the supply amount of the gas-fluid increases the pressure applied to the nozzle, and the nozzle and the gas-fluid supply pipe may not be able to withstand the pressure. Therefore, the gas / fluid supply rate / slurry supply rate is usually
It is 1500 or more, preferably 1700 or more, more preferably 2000 or more, preferably 5000 or less, more preferably 4000 or less.

The upper and lower limits of the slurry supply amount and the gas-fluid supply amount are caused by the capacity of the equipment, and the value of gas-fluid supply quantity / slurry supply quantity is within the capacity range of the equipment. It may be arbitrarily selected within the range. In the present invention, the ratio of the gas-fluid supply amount and the slurry supply amount described above (gas-fluid supply amount / slurry supply amount)
Is important for controlling the particle size, but generally, at the industrial level, the slurry supply rate may be 100 cc / min or more, and the gas-fluid supply rate may be 100000 cc / min or more.

In the present invention, it is preferable that the nozzle gap of the slurry supply section of the four-fluid nozzle is 0.1 to 5.0 mm. If the nozzle gap is too small, it may not be possible to use a highly concentrated slurry. If it is too large, it is difficult to control the particle size. The nozzle gap is usually 0.
It is 1 mm or more, preferably 0.3 mm or more, usually 5.0 mm or less, preferably 1.0 mm or less, more preferably 0.7 mm or less.

In the above method, since a large amount of droplets can be sprayed with one nozzle, productivity can be improved. Also, since the formed droplets are extremely fine,
The particle size of the lithium-transition metal composite oxide obtained by drying and calcining this can be reduced. Note that the droplet miniaturization technique is described in Japanese Patent No. 2797080, and the droplet formation itself can be more easily carried out by referring to the above-mentioned known documents.

The slurry that has become droplets is dried. At the time of drying, it is preferable to introduce a drying gas from the upper part of the drying tower toward the lower part by downflow. With such a structure, the throughput per unit volume of the drying tower can be greatly improved. In addition, when spraying liquid droplets in a substantially horizontal direction, it is possible to greatly reduce the diameter of the drying tower by suppressing the liquid droplets that have been sprayed in the horizontal direction with downflow gas. Is possible. Dry gas temperature is usually 50
C. or higher, preferably 70.degree. C. or higher, and the upper limit is usually 120.degree. C. or lower, preferably 100.degree. C. or lower. If the temperature is too high,
The obtained granulated particles have many hollow structures, and the packing density of the powder tends to decrease. On the other hand, if it is too low, problems such as powder sticking and blockage due to water condensation at the powder outlet part occur. there is a possibility.

The granulated particles can be obtained by spray-drying in this manner, and the granulated particle diameter is preferably 14 μm or less, more preferably 12 μm or less in terms of median diameter. However, since it is difficult to obtain a too small particle size, it is usually 4 μm or more, preferably 5 μm or more. The particle size of the granulated particles can be controlled by appropriately selecting the spray type, pressurized gas flow supply rate, slurry supply rate, drying temperature and the like.

The granulated particles obtained by such treatment are then fired. Although the firing temperature varies depending on the kind of the transition metal and the substitution element used as the raw material,
Usually, the temperature is 500 ° C or higher, and the temperature is usually 1000 ° C or lower. If the temperature is too low, a long firing time may be required to obtain a lithium-transition metal composite oxide having good crystallinity. Further, if the temperature is too high, a crystal phase other than the intended lithium-transition metal composite oxide is generated,
Alternatively, a lithium-transition metal composite oxide having many defects is generated, which may lead to deterioration in the capacity of the secondary battery or the collapse of the crystal structure due to charge / discharge.

On the other hand, the firing time varies depending on the temperature, but is usually 30 minutes or more and 50 hours or less in the above temperature range. If the firing time is too short, it becomes difficult to obtain a lithium-transition metal composite oxide having good crystallinity, and if it is too long, it is not practical. In order to obtain a lithium-transition metal composite oxide with few crystal defects, it is preferable to cool slowly after the firing reaction, for example, to gradually cool at a cooling rate of 5 ° C./min or less.

The atmosphere during firing may be an oxygen-containing gas atmosphere such as air or an inert gas atmosphere such as nitrogen or argon, depending on the composition and structure of the compound to be produced.
For example, when producing a lithium-manganese composite oxide having a layered structure, it is preferable to carry out in a vacuum or in an inert atmosphere such as nitrogen or argon, LiCoO ₂ system, LiNiO ₂ system,
Alternatively, when producing a spinel type lithium manganese composite oxide or the like, it is preferable to carry out at least the slow cooling process in the air or an oxygen-containing atmosphere such as oxygen.

As a method for firing and cooling the lithium manganese oxide, for example, JP-A-9-306490 and JP-A-9-306493 can be used.
No. 9-259880, etc., after calcination, main firing is performed in an oxygen atmosphere at a temperature of about 600 to 900 ° C, and then 10 ° C / min or less up to about 500 ° C or less. Examples thereof include a method of slow cooling at a rate, a method of calcination, a main firing at a temperature of about 600 to 900 ° C. in an air or oxygen atmosphere, and a method of annealing at a temperature of about 400 ° C. in an oxygen atmosphere.

The firing temperature of the lithium nickel composite oxide is usually 500 ° C. or higher, preferably 550 ° C. or higher, and usually 1000 ° C. or lower, preferably 900 ° C. or lower. If the firing temperature is too low, it is difficult to obtain a lithium nickel composite oxide having good crystallinity. Further, if the firing temperature is too high, a phase other than the intended lithium nickel composite oxide may be generated, or a lithium nickel composite oxide with many defects may be generated. Also, when the above reaction is heated from room temperature to temperature, in order to carry out the reaction more uniformly,
For example, the temperature may be gradually raised at a temperature of 5 ° C. or less per minute, or the temperature may be temporarily stopped midway and a holding time at a constant temperature may be set.

The firing time during the firing treatment is usually 1 hour or more.
It is 100 hours or less, preferably 2 hours or more and 50 hours or less. If the time is less than the above range and the time is too short, it is difficult to obtain a lithium nickel composite oxide having good crystallinity, and a reaction time that is too long beyond this range is industrially inappropriate. The atmosphere during the firing treatment can be appropriately selected and usually selected from oxygen or air.

In order to obtain a lithium-nickel composite oxide with few defects, it is preferable to cool slowly to a certain temperature after the above firing, and to 600 ° C., preferably 400 ° C., at a cooling rate of 5 ° C. or less per minute. It is preferable to gradually cool. The heating device used for firing is not particularly limited as long as it can achieve the above temperature and atmosphere, and for example, a box furnace, a tubular furnace, a tunnel furnace, a rotary kiln or the like can be used.

The lithium transition metal composite oxide thus obtained preferably has a median diameter of 0.1 to 3 μm as a primary particle diameter, and a median diameter of 1 to 14 μm as a secondary particle diameter.
And the specific surface area by nitrogen adsorption is preferably 0.1 to ⁵ m ² / g. The size of the primary particles can be controlled by the firing temperature, the firing time and the like, and the particle diameter of the primary particles can be increased by increasing these conditions. The particle size of the secondary particles can be controlled by the spraying conditions such as the gas-liquid ratio in the pulverization or spray drying step before firing. The specific surface area can be controlled by the particle size of the primary particles and the particle size of the secondary particles, and decreases by increasing the particle size of the primary particles and / or the particle size of the secondary particles. Further, the packing density is preferably 1.50 g / cc or more in terms of tap density (after 200 taps).

Using the obtained lithium-transition metal composite oxide as an active material, electrodes and batteries can be manufactured. For example, as an example of a battery, a lithium secondary battery having a positive electrode, a negative electrode, and an electrolyte can be given. In particular,
There can be mentioned a secondary battery in which an electrolyte is present between the positive electrode and the negative electrode, and a separator is arranged between them so that the positive electrode and the negative electrode do not come into contact with each other as necessary.

The positive electrode is a mixture of the lithium-transition metal composite oxide (positive electrode active material) obtained in the present invention, a binder and, if necessary, a conductive agent, and a fixed amount of a solvent for uniformly dispersing them. It can be obtained by coating the mixture on a current collector and then drying it after mixing with the above to form a coating material. Examples of the conductive material used here include natural graphite, artificial graphite, and acetylene black, and as the binder, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl acetate, polymethylmethacrylate, polyethylene, nitrocellulose, etc. However, examples of the solvent for dispersion include N-methylpyrrolidone, tetrahydrofuran, dimethylformamide and the like. Examples of the material of the current collector include aluminum and stainless steel. The positive electrode is usually compacted by a roller press or other method after forming the positive electrode mixture layer on the current collector.

On the other hand, as the negative electrode, a carbon-based material (natural graphite, pyrolytic carbon or the like) coated on a current collector such as Cu, or a lithium metal foil or a lithium-aluminum alloy can be used. The electrolyte used in the lithium secondary battery is a non-aqueous electrolytic solution, and is usually prepared by dissolving an electrolytic salt in a non-aqueous solvent. Electrolyte salts include LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiB
Lithium salts such as F ₄ , LiBr and LiCF ₃ SO ₃ can be mentioned. In addition, examples of the non-aqueous solvent include tetrahydrofuran, 1,4-dioxane, dimethylformamide, acetonitrile, benzonitrile, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and the like. These electrolytic salts and non-aqueous solvents may be used alone or in combination of two or more.

As the separator used in the battery,
Examples thereof include polymers such as polytetrafluoroethylene, polyethylene, polypropylene, polyester, and non-woven fabric filters such as glass fibers, and composite non-woven fabric filters of glass fibers and polymer fibers.

[0051]

EXAMPLES The method of the present invention will be described more specifically below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. The slurry concentration in the following examples and comparative examples is defined by the following formula.

[0052]

[Equation 1] Slurry concentration = (LiOH ・ H ₂ O + Mn ₂ O ₃ + AlOOH) / (LiO
H ・ H ₂ O + Mn ₂ O ₃ + AlOOH + H ₂ O) × 100

[0053]

[Formula 2] Slurry concentration = (NiO + Co (OH) ₂ + AlOOH) / (NiO + Co (O
H) ₂ + AlOOH + H ₂ O) × 100

[0054]

[Formula 3] Slurry concentration = (LiOH ・ H ₂ O + NiO + Mn ₂ O ₃ + Co (O
H) ₂ ) / (LiOH ・ H ₂ O + NiO + Mn ₂ O ₃ + Co (OH) ₂ + H ₂ O) × 100 where LiOH ・ H ₂ O, Mn ₂ O ₃ , AlOOH, NiO, Co (OH) ₂ , H ₂ O
Means the charged weight (kg), respectively.

The gas-liquid ratio is defined by the following equation.

[0056]

[Equation 4] Gas-liquid ratio = Spraying air supply rate (L / min) / Slurry supply rate (L / min)

Example 1 Mn ₂ O ₃ , AlOOH, and LiOH.H ₂ O were used as Li: Mn: Al = compositions in the final spinel type lithium manganese composite oxide.
It was weighed so as to be 1.04: 1.88: 0.12 (molar ratio), and pure water was added thereto to prepare a slurry having a solid content concentration (slurry concentration) of 29.2% by weight. While stirring this slurry, a circulating medium agitation type wet pulverizer was used to pulverize until the average particle size of the solid content in the slurry became 0.3 μm, and then a nozzle having a droplet atomizing mechanism was provided. Spray dryer (Fujisaki Electric Co., Ltd., Micro mist dryer MDP-
Spray drying was carried out using 050, a nozzle type circle edge nozzle, and a drying tower size of 2500 mmφ × 4800 mmH).

At this time, the amount of dry gas introduced was 23 m ³ / min, and the temperature of the dry gas inlet was 90 ° C. As the spray nozzle, use a type with a diameter of 30 mmφ and capable of horizontal spraying in the direction of 360 ° (annular). The slurry outlet clearance of the nozzle is 500 μm and the clearance of the pressurized gas outlet for atomizing the slurry is It was set to 350 μm. The slurry supply rate was 0.56 L / min, and the atomizing air supply rate was 1200 L / min. The gas-liquid ratio was 2142. The exhaust gas temperature during spray drying under these conditions was 45 ° C. The dried granulated particles were collected by a cyclone and then calcined at 900 ° C. for 10 hours. X
When the line diffraction was measured, it was confirmed to have a structure of cubic spinel type lithium manganese composite oxide. The particle size distribution of the particles was measured using a laser diffraction / scattering particle size distribution measuring device (LA920 manufactured by HORIBA). As a result, the average particle diameter was 10.2 μm and the maximum particle diameter was 29.9 μm.

10 g of the positive electrode active material thus obtained
Then, acetylene black (AB) and polyvinylidene fluoride (PVDF) were dispensed into a 50cc polyethylene container using N-methyl-2-pyrrolidone as a solvent so that the solid content concentration was 40 wt%. The compounding ratio of each component at this time is the positive electrode active material: AB:
PVDF = 90: 5: 5 (wt%). Further, 20 g of 1 mmφ zirconia beads was added, the container was tightly closed, and the container was set on a shaker and mixed for 30 minutes. Using the applicator with a clearance of 350 μm, mix the mixed cathode fluid with the positive electrode.
Apply it on an aluminum electrode sheet with a thickness of 21 μm and keep it at 120 ° C.
After being dried in, it was punched out to obtain a positive electrode pellet of 12 mmφ. The punched pellets were subjected to a consolidation treatment with a hand press at a pressure of 24 Mpa for 1 minute.

A coin-type battery was assembled using the pellets and the battery was evaluated. At this time, lithium metal was used as the negative electrode material, and a solution prepared by dissolving 1 mol / L lithium hexafluorophosphate (LiPF ₆ ) in a 3: 7 mixed solvent of ethylene carbonate and diethyl carbonate was used as the electrolytic solution. . Using this battery, the charge / discharge capacity when charging / discharging at a current density of 1 mA / cm ² was measured.
It was confirmed to have good characteristics such as g, discharge capacity of 117 mAh / g, and charge / discharge efficiency of 97.5%.

Regarding the droplet refining technique, since the velocity of the pressurized gas flow and the slurry thin film flow is in the supersonic region, particularly with respect to the atomization of the spray in a slurry system containing solids having different specific gravities. Regarding the obtained granulated particles, it was feared that the battery performance might be deteriorated due to uneven distribution of some compounds, compositional variation, etc., but it was found that very good battery characteristics were obtained by the above examples.

Example 2 The same operation as in Example 1 was carried out except that the slurry feed rate was 0.7 L / min and the atomizing air feed rate was 1200 L / min (gas-liquid ratio 1714). As a result, the average particle diameter was 11.8 μm and the maximum particle diameter was 34.2 μm. Example 3 The same operation as in Example 1 was carried out except that the slurry supply rate was 0.42 L / min and the atomizing air supply rate was 1200 L / min (gas-liquid ratio 2857). As a result, the average particle diameter was 8.7 μm and the maximum particle diameter was 22.8 μm.

Example 4 The same operation as in Example 1 was carried out except that the slurry feed rate was 0.7 L / min and the atomizing air feed rate was 1500 L / min (gas-liquid ratio 2142). As a result, the average particle size was 9.4 μm and the maximum particle size was 34.2 μm. Example 5 Although the slurry concentration used in Example 1 was 29.2%, the same operation was carried out except that a slurry having a slurry concentration of 35% was used instead.

As a result, the average particle diameter was 12.1 μm and the maximum particle diameter was 39.2 μm. Example 6 The slurry concentration used in Example 1 was 29.2%, but the same operation was performed except that a slurry having a slurry concentration of 10% was used instead. As a result, NiO, Co (OH) ₂ , and AlOOH having an average particle size of 9.4 μm and a maximum particle size of 26.1 μm were added to Ni: Co: Al = 0.80: 0.15: 0.05.
(Mole ratio) was weighed, and pure water was added to this to prepare a slurry having a solid content concentration (slurry concentration) of 34.2% by weight. While stirring this slurry, a circulating medium agitation type wet pulverizer was used to pulverize until the average particle size of the solid content in the slurry became 0.3 μm, and then a nozzle having a droplet atomizing mechanism was provided. Spray dryer (Fujisaki Electric Co., Ltd., Micro mist dryer MDP-050, Nozzle type is circle edge nozzle, Drying tower size is 2500mmφ × 48
00 mmH) was used for spray drying.

At this time, the amount of introduced dry gas was 23 m ³ / min, and the temperature of the dry gas inlet was 90 ° C. As the spray nozzle, use a type with a diameter of 30 mmφ and capable of horizontal spraying in the direction of 360 ° (annular). The slurry outlet clearance of the nozzle is 500 μm and the clearance of the pressurized gas outlet for atomizing the slurry is It was set to 350 μm. The slurry supply rate was 0.56 L / min, and the atomizing air supply rate was 1800 L / min. The gas-liquid ratio was 3214. The exhaust gas temperature during spray drying under these conditions was 45 ° C.

Lithium hydroxide pulverized powder and the spray-dried powder produced by the above operation were mixed with Li: Ni: Co: Al = 1.05: 0.80: 0.
Dry mixing was carried out so that the ratio was 15: 0.05 (molar ratio). This mixed powder was placed in an alumina tray and baked in oxygen at 740 ° C. for 6 hours. When the calcined powder was crushed and classified and X-ray diffraction was measured, it was confirmed that the powder had a hexagonal layered rock salt structure. The particle size distribution of these particles can be measured by laser diffraction
It was performed using a scattering type particle size distribution measuring device (LA920 manufactured by HORIBA). As a result, the average particle size was 7.4 μm, and the maximum particle size was 22.8 μm.
Met.

Using this Ni-based positive electrode material, a coin-type battery was evaluated in the same manner as in Example 1, and as a result, the charging capacity was 204.2 mAh /
It was confirmed that it had good characteristics of g, discharge capacity of 175.4 mAh / g, and charge / discharge efficiency of 85.9%. Example 8 LiOH.H ₂ O, NiO, Mn ₂ O ₃ , Co (OH) ₂ was added to Li: Ni: Mn: Co =
1.05: 0.65: 0.20: 0.15 (molar ratio) Weigh it so that pure water is added to it and the solid content concentration (slurry concentration) 2
A 5.9 wt% slurry was prepared. While stirring this slurry, a circulating medium agitation type wet pulverizer was used to pulverize until the average particle size of the solid content in the slurry became 0.3 μm, and then a nozzle having a droplet atomizing mechanism was provided. Spray drying was performed using a spray dryer (Fujisaki Electric Co., Ltd., Micro mist dryer MDP-050, nozzle type is circle edge nozzle, drying tower size is 2500 mmφ × 4800 mmH).

At this time, the amount of introduced dry gas was 23 m ³ / min, and the inlet temperature of dry gas was 90 ° C. As the spray nozzle, use a type with a diameter of 30 mmφ and capable of horizontal spraying in the direction of 360 ° (annular). The slurry outlet clearance of the nozzle is 500 μm and the clearance of the pressurized gas outlet for atomizing the slurry is It was set to 350 μm. The slurry supply rate was 0.56 L / min, and the atomizing air supply rate was 1800 L / min. The gas-liquid ratio was 3214. The exhaust gas temperature during spray drying under these conditions was 45 ° C.

This mixed powder was placed in an alumina tray,
It was calcined in air at 835 ° C for 15 hours. Crush and classify the fired powder X
When the line diffraction was measured, it was confirmed that it had a hexagonal layered rock salt structure. The particle size distribution of these particles is measured using a laser diffraction / scattering particle size distribution measuring device (HORIBA LA9
20). As a result, the average particle diameter was 5.5 μm and the maximum particle diameter was 15.2 μm.

Using this Ni-based positive electrode material, a coin-type battery was evaluated in the same manner as in Example 1, and as a result, the charging capacity was 188.3 mAh /
It was confirmed that it had good characteristics such as g, discharge capacity 164.2 mAh / g, and charge / discharge efficiency 87.2%. Comparative Example 1 The slurry concentration used in Example 1 was 29.2%, but the same operation was performed except that a slurry having a slurry concentration of 50% was used instead. As a result, the nozzle was clogged immediately after spraying, and dry granulation of the powder could not be performed.

Comparative Example 2 The same operation was carried out as in Example 1, except that the slurry supply rate was 0.84 L / min and the atomizing air rescue rate was 1200 L / min (gas-liquid ratio 1430). As a result, the average particle diameter was 14.1 μm and the maximum particle diameter was 51.5 μm.

[0072]

[Table 1]

[0073]

INDUSTRIAL APPLICABILITY According to the present invention, a method for producing a lithium transition metal composite oxide suitable as a positive electrode active material for a lithium ion secondary battery, particularly a lithium transition metal composite oxide capable of charging and discharging at a high current density. It is possible to provide a method for mass-producing goods at low cost.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a nozzle portion of a spray dryer that can be used for spray drying, with a partial cross section exposed.

FIG. 2 is a schematic cross-sectional view showing an enlarged nozzle tip of FIG. 1 together with a gas flow and a slurry flow.

[Explanation of symbols]

1 nozzle 2 slope 4 Gas outlet 5 Slurry outlet 7 gas supply pipe 8 Slurry supply pipe

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 10/40 H01M 10/40 ZF term (reference) 4G048 AA04 AB01 AB06 AC06 AD04 AD06 AE05 5H029 AJ02 AJ14 AK03 AL06 AL07 AL12 AM02 AM03 AM05 AM07 CJ02 CJ08 CJ28 HJ04 HJ05 HJ10 5H050 AA02 AA19 BA17 CA09 CB07 CB08 CB12 FA17 FA19 GA02 GA10 HA02 HA04 HA05 HA10 HA20

Claims (13)

[Claims] 1. A slurry containing a lithium source and a transition metal source is spray-dried using a four-fluid nozzle and is then subjected to a calcination treatment, or a slurry containing a transition metal source is used with a four-fluid nozzle. After spray-drying, in a method for producing a lithium transition metal oxide that is subjected to a firing treatment by mixing a lithium source with this, the slurry concentration is 1 to 40 wt%, and the amount of slurry supplied in spraying with a four-fluid nozzle and The median system characterized in that the ratio of the gas / fluid supply amount is the gas / fluid supply amount / slurry supply amount = 1500 or more.
A method for producing a lithium-transition metal composite oxide having a size of 14 μm or less. 2. The method according to claim 1, wherein the transition metal source is a compound selected from the group consisting of at least Mn compound, Ni compound and Co compound. 3. The production method according to claim 1, wherein a slurry containing a lithium source and a transition metal source is spray-dried using a four-fluid nozzle, and the slurry is subjected to a firing treatment. 4. The manufacturing method according to claim 1, wherein the nozzle gap of the slurry supply section of the four-fluid nozzle is 0.1 to 1.0 mm. 5. The injection velocity of the gas flow is a gas linear velocity of 100 to 100.
It is 0 m / s, The manufacturing method in any one of Claims 1-4. 6. The average particle size of the solid matter in the slurry is 2 μm.
It is the following, The manufacturing method in any one of Claims 1-5. 7. The slurry is B, Al, Ti, V, Cr, Fe, S.
n, Cu, Zn, Mg, Ga, Zr, Bi, Ge, Nb, Ta, Be, Ca and S
The manufacturing method according to any one of claims 1 to 6, comprising at least one metal element source selected from the group consisting of c. 8. The metal element source is B, Al, Ti, V, Cr, Fe,
Sn, Cu, Zn, Mg, Ga, Zr, Bi, Ge, Nb, Ta, Be, Ca and
Oxides, hydroxides of elements selected from the group consisting of Sc
The method according to claim 7, wherein the method is at least one selected from oxyhydroxide, nitrate, sulfate, carbonate, dicarboxylic acid salt, fatty acid salt, and ammonium salt. 9. The lithium source is Li ₂ CO ₃ , LiNO ₃ , LiOH, L.
iOH ・ H ₂ O, Li ₂ O, Li acetate, Li dicarboxylic acid, L citric acid
The production method according to claim 1, wherein the production method is at least one selected from the group consisting of i, fatty acid Li, alkyllithium, and lithium halide. 10. The transition metal source is Mn ₃ O ₄ , Mn ₂ O ₃ , MnO ₂ ,
MnCO ₃ , Mn (NO ₃ ) ₂ , MnSO ₄ , manganese acetate, manganese dicarboxylate, manganese citrate, fatty acid manganese, manganese oxyhydroxide, manganese hydroxide, manganese halide, nickel oxide, nickel hydroxide The method according to claim 1, wherein the method is at least one selected from the group consisting of nickel oxyhydroxide, nickel halide, and nickel carbonate. 11. The method according to claim 1, wherein the lithium-transition metal composite oxide is represented by the following general formula (I). ## STR1 ## _{Li 1 + x Mn 2-xy} M y O 4 + δ ··· (I) ( here, x is the number of -0.1~0.1, y is the number of 0 to 0.3, M is B, A
l, Ti, V, Cr, Fe, Sn, Cu, Zn, Mg, Ga, Zr, Bi, Ge,
(At least one element selected from the group consisting of Nb, Ta, Be, Ca and Sc, and δ represents a number of -0.1 to 0.1). 12. A coating material containing a mixture containing the lithium-transition metal composite oxide obtained by the method according to claim 1 and a binder, and a solvent is applied onto a current collector. A method for producing an electrode, which comprises drying. 13. A lithium secondary battery using the lithium transition metal composite oxide obtained by the method according to claim 1 as a positive electrode active material.