JP2005324973A - Lithium-transition metal combined oxide and its manufacturing method, and lithium secondary battery positive electrode and lithium secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a lithium-transition metal combined oxide which has a high tap density and a high press density when forming electrodes while suppressing hollow particles in spray drying, when manufacturing the lithium-transition metal combined oxide by spray-drying slurry containing a transition metal compound and a lithium compound and then firing it. <P>SOLUTION: In the method of manufacturing the lithium-transition metal combined oxide by spray-drying slurry containing a manganese compound and the lithium compound and then firing it, LiOH and Li<SB>2</SB>O<SB>3</SB>are used together as the lithium compound, the ratio of the Li atoms originated from Li<SB>2</SB>O<SB>3</SB>to total Li atoms is made to be 10-60 mol%. Alternatively, in the method of manufacturing the lithium-transition metal combined oxide by spray-drying slurry containing a manganese compound, a cobalt compound, a nickel compound, and the lithium compound and then firing it, LiOH and Li<SB>2</SB>O<SB>3</SB>are used together as the lithium compound, and the ratio of the Li atoms originated from Li<SB>2</SB>O<SB>3</SB>to the total Li atoms is made to be 5-95 mol%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a lithium transition metal composite oxide, a lithium transition metal composite oxide obtained by this method, a positive electrode for a lithium secondary battery containing this lithium transition metal composite oxide, and the lithium secondary The present invention relates to a lithium secondary battery having a positive electrode for a battery.

  Lithium secondary batteries use carbon materials that can occlude and release lithium ions instead of metallic lithium as the negative electrode active material, greatly improving its safety and entering the practical stage. .

On the other hand, as a positive electrode active material of a lithium secondary battery, a lithium cobalt composite oxide having a standard composition represented by LiCoO ₂ has been used. However, cobalt, which is the main constituent element of this lithium cobalt composite oxide positive electrode, has a small amount of reserves, is expensive, and is toxic to the human body. Has been done.

Typical examples of the lithium manganese composite oxide represented by LiMn ₂ O ₄ and LiMnO ₂ , the lithium nickel composite oxide represented by LiNiO ₂ , and the lithium nickel manganese cobalt composite oxide represented by Li (NiMnCo) O ₂ It is a system. Since these new positive electrodes have a lower cobalt content than lithium cobalt composite oxide, the influence of the above problems is reduced.

  Conventionally, as a method for producing a lithium transition metal composite oxide used for a positive electrode active material of a lithium secondary battery, for example, in Patent Document 1, a slurry containing a lithium compound and a transition metal compound is spray-dried and then fired. Describes a method for producing a lithium transition metal composite oxide. Patent Document 1 describes lithium hydroxide, lithium carbonate, lithium nitrate, lithium oxide, and the like, or hydrates thereof, as a lithium compound source.

  However, according to the research of the present inventors, when lithium hydroxide is used as a lithium compound source, the resulting lithium transition metal composite oxide becomes hollow particles, and when this is used as a positive electrode active material, It has been found that there is a problem of reducing the battery capacity per unit volume. That is, as shown in a cross-sectional SEM photograph in Comparative Example 1 described later, a slurry is formed with a transition metal compound using lithium hydroxide monohydrate well known as a lithium compound source of a lithium transition metal composite oxide. And when this was spray-dried and baked, it turned out that there exists a problem which a hollow particle tends to produce | generate.

On the other hand, when lithium carbonate is used as the lithium compound source, the resulting lithium transition metal composite oxide is unlikely to be a hollow particle, but because of the small amount of dissolved salt in the slurry, The granulated particles do not collapse, or the composite with the transition metal due to firing is difficult to progress, and it is difficult to obtain dense particles, so the tap density is reduced, or the active material is coated with a binder on the current collector It has been found that there is a problem that the density (press density) of the active material layer when the layer is formed decreases.
JP 2001-146426 A

  Therefore, in the present invention, when a slurry containing a transition metal compound and a lithium compound is spray-dried and then calcined to produce a lithium transition metal composite oxide, the tap is generated while suppressing the formation of hollow particles in the spray-drying. An object of the present invention is to provide a method for producing a lithium transition metal composite oxide having a high press density when the density and electrodes are formed.

  As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by using lithium carbonate and lithium hydroxide together as a lithium compound source, despite the fact that lithium carbonate and lithium hydroxide cannot be obtained alone. The present invention has been completed.

  That is, the gist of the present invention is that a slurry containing a manganese compound and a lithium compound is spray-dried and then fired to produce a lithium transition metal composite oxide, wherein the lithium compound contains lithium hydroxide and lithium carbonate. The method for producing a lithium transition metal composite oxide is characterized in that the ratio of Li atoms derived from lithium carbonate to all Li atoms is 10 to 60 mol%. In this method, the slurry may further contain an aluminum compound.

  Another aspect of the present invention is a method for producing a lithium transition metal composite oxide by spray drying a slurry containing a manganese compound, a cobalt compound, a nickel compound, and a lithium compound, and then firing the slurry. Includes a lithium hydroxide and lithium carbonate, and the ratio of Li atoms derived from lithium carbonate to all Li atoms is from 5 to 95 mol%.

  Although the details of the mechanism by which the effect of the present invention is obtained by using lithium hydroxide and lithium carbonate in combination are not yet clear, it is estimated as follows.

  That is, since lithium hydroxide has high solubility in water, when slurry-like raw materials are spray-dried, it is easy to form a LiOH film in the initial stage of spray-drying, and droplets that are being dried with water evaporated after the film is formed There is a tendency that the internal pressure increases and the coating is broken to make the particles hollow. On the other hand, lithium carbonate, unlike lithium hydroxide, has a low solubility in water, so it is difficult to form a film. However, since it is less reactive than lithium hydroxide, it is granulated by spray drying. Particles are fragile and complexation is difficult to proceed.

  On the other hand, when lithium hydroxide and lithium carbonate are used in combination at a specific ratio, they are completely opposite in terms of solubility in water. In the present invention, in the process of studying a suitable mixing ratio of lithium hydroxide and lithium carbonate, the difference in reactivity and the difference in film formation are offset or alleviated from each other, thereby preventing hollowing and reducing the density. It was presumed that it would be possible.

  In such a method for producing a lithium transition metal composite oxide of the present invention, after the slurry is spray-dried, the slurry is sufficiently held at a temperature lower than the melting point of lithium carbonate (726 ° C.), and then at a temperature equal to or higher than the melting point of lithium carbonate. It is preferable to fire.

  The gist of the present invention is also a lithium transition metal composite oxide produced by such a method for producing a lithium transition metal composite oxide, and a positive electrode for a lithium secondary battery containing the lithium transition metal composite oxide and a binder. And a lithium secondary battery having a positive electrode for a lithium secondary battery, a negative electrode capable of occluding and releasing lithium ions, and an electrolyte.

  According to the present invention, a lithium transition metal composite oxide having a high filling rate can be produced. By using this lithium transition metal composite oxide as a positive electrode active material, a lithium secondary battery having a high battery capacity per unit volume can be obtained. A battery can be provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention. The content of is not specified.

[Method for producing lithium transition metal composite oxide]
<Raw compound>
In the present invention, the manganese compound, nickel compound, and cobalt compound used for the preparation of the slurry for spray drying are appropriately selected from those known to be used as raw materials for lithium transition metal composite oxides. Good. Specifically, manganese, nickel, and cobalt oxides; hydroxides; halides; inorganic acid salts such as carbonates, sulfates, and nitrates; organic acid salts such as acetates.

More specifically, as the manganese compound, manganese oxides such as Mn ₂ O ₃ , MnO ₂ and Mn ₃ O ₄ ; hydroxides such as Mn (OH) ₂ ; MnCO ₃ , Mn (NO ₃ ) ₂ , Examples include manganese salts such as MnSO ₄ , manganese acetate, manganese dicarboxylate, manganese citrate, and fatty acid manganese; oxyhydroxides, halides, and the like. As Mn ₂ O _3, it may be used those produced by heat-treating compound such as MnCO ₃ and MnO _2. Preferably, compounds such as oxides such as Mn ₂ O ₃ , Mn ₃ O ₄ and MnO ₂ , and hydroxides such as Mn (OH) ₂ are used.

More specific examples of the nickel compound include oxides such as NiO and NiO ₂ ; hydroxides such as Ni (OH) ₂ ; oxyhydroxides such as NiOOH; halides such as NiCl ₂ ; NiCO ₃ Etc. Preferably, a compound such as an oxide such as NiO or a hydroxide such as Ni (OH) ₂ is used.

More specifically, examples of the cobalt compound include hydroxides such as Co (OH) ₂ ; oxyhydroxides such as CoOOH; oxides such as CoO and Co ₂ O ₃ ; halides such as CoCl ₂ ; NO ₃ ) nitrates such as ₂ · 6H ₂ O; sulfates such as Co (SO ₄ ) ₂ · 7H ₂ O; CoCO _{3 and the} like. Preferably, compounds such as cobalt hydroxide, cobalt oxyhydroxide, and cobalt carbonate are used.

As the lithium compound, lithium hydroxide (LiOH) and lithium carbonate (Li ₂ CO ₃ ) are used in combination. In addition to these two types of lithium compounds, lithium compounds include lithium oxides; halides; inorganic acid salts such as sulfates and nitrates; and organic acid salts such as acetates as long as the effects of the present invention are not impaired. In this case, lithium hydroxide and lithium carbonate are contained in a majority amount (that is, 50% by weight or more), particularly 70% by weight or more, particularly 90% by weight or more, based on the entire lithium compound. It is preferable to contain it in order to ensure the effects of the present invention. In particular, it is most desirable that the total amount of lithium compounds is lithium carbonate and lithium hydroxide.

  The optimum amount of lithium carbonate in the lithium compound varies depending on the composition of the lithium transition metal composite oxide to be produced. The lithium transition metal composite oxide composition and the amount of lithium carbonate will be described below.

Examples of the lithium transition metal composite oxide include the following.
(1) Lithium transition metal composite oxide whose main transition metal is manganese (hereinafter sometimes referred to as “lithium manganese composite oxide”)
(2) Lithium transition metal composite oxide containing manganese, cobalt and nickel as transition metals (hereinafter sometimes referred to as “layered lithium composite oxide”)

(1) Lithium manganese composite oxide In the present invention, when the lithium transition metal composite oxide to be produced is a lithium manganese composite oxide whose main transition metal is manganese, the lithium transition metal composite oxide is lithium having a spinel structure. A manganese composite oxide is preferable. Note that the main transition metal is manganese means that the molar ratio of manganese to all transition metals in the lithium transition metal composite oxide exceeds 50%.

The composition of this lithium transition metal composite oxide is represented, for example, by the following formula (I).
_{Li a Mn 2-b M b} O 4 ‥ (I)
(0.8 ≦ a ≦ 1.5, 0 <b ≦ 1.0, M represents a metal element other than Li and Mn)

  In formula (I), M represents a metal element other than Li and Mn, and is usually at least one selected from the group consisting of B, Al, Fe, Sn, Cr, Cu, Ti, Zn, Co, Ni, and Zr. And preferably Al.

  a is usually 0.8 or more, preferably 1.0 or more, and usually 1.5 or less, preferably 1.2 or less. B is usually greater than 0, preferably 0.05 or more, and usually 1 or less, preferably 0.5 or less.

  When producing such a lithium manganese composite oxide, the lower limit of the proportion of Li atoms derived from lithium carbonate relative to the total Li of the lithium compound source is 10 mol% or more, preferably 15 mol% or more, and the upper limit is , 60 mol% or less, preferably 50 mol% or less. Below this lower limit, the tap density and the press density tend to decrease, and even when the upper limit is exceeded, the tap density and the press density tend to decrease.

(2) Layered lithium composite oxide When the lithium transition metal composite compound is a layered lithium composite oxide containing nickel, manganese and cobalt as transition metals, the lithium transition metal composite oxide is a lithium transition metal having a hexagonal layered rock salt structure. A composite oxide is preferable.

A preferable composition of the lithium transition metal composite oxide having a hexagonal layered rock salt structure (layered lithium composite oxide) produced by firing is represented by the following formula (II).
_{Li c (Ni d Mn e Co} f Q g) O 2 ‥ (II)
(0.8 ≦ c ≦ 1.3, 0 ≦ d ≦ 1, 0 ≦ e ≦ 1, 0 ≦ f ≦ 1, 0 ≦ g ≦ 1, d + e + f + g = 1, Q is Fe, Cr, V, Ti, Cu At least one element selected from the group consisting of Al, Ga, Bi, Sn, Zn, Mg, Ge, Nb, Ta, Be, B, Ca, Sc and Zr)

  In the formula (II), Q is selected from the group consisting of Fe, Cr, V, Ti, Cu, Al, Ga, Bi, Sn, Zn, Mg, Ge, Nb, Ta, Be, B, Ca, Sc and Zr. Preferably, V, Nb, Cr, Fe, Bi, Al, etc. can be mentioned.

  c is usually 0.8 or more, usually 1.3 or less, preferably 1.2 or less. D is a number from 0 to 1; e is a number from 0 to 1; f is a number from 0 to 1; g is a number from 0 to 1; and d, e, f, and g The sum is 1.

  When producing such a layered lithium composite oxide, the lower limit of the proportion of Li atoms derived from lithium carbonate relative to the total Li of the lithium compound source is 5 mol% or more, preferably 15 mol% or more, and the upper limit is 95 mol% or less, preferably 80 mol% or less. If the lower limit is not reached, the tap density and the press density tend to decrease, and if the upper limit is exceeded, the press density tends to decrease.

  In any of the lithium manganese composite oxide, the layered lithium composite oxide, and any lithium transition metal composite oxide, the raw material compound slurry includes at least one transition metal compound selected from a manganese compound, a cobalt compound, and a nickel compound. In addition, a metal compound other than the lithium compound can be contained, and the finally obtained lithium transition metal composite oxide can contain a metal other than manganese, cobalt, nickel, and lithium.

  Lithium transition metal composite oxides containing these metals often have better performance as the positive electrode active material of lithium secondary batteries than the original composite oxides. It is considered that the transition metal selected from cobalt and nickel is substituted to exist in the structure of the lithium transition metal composite oxide and stabilize the structure.

  The basic composition of the lithium transition metal composite oxide is composed of any of transition metals of manganese, nickel, and cobalt and lithium, but a part of this transition metal can be substituted with another transition metal. In this case, as in the case of substitution with a metal other than the transition metal, the performance of the lithium transition metal composite oxide as the positive electrode active material is often improved. This is also considered to be due to the same reason as described above. When a part of the transition metal of the lithium transition metal composite oxide is substituted with another transition metal, the substitution ratio is preferably 50% or less, particularly preferably 30% or less in terms of atomic ratio.

  As with transition metals, metals that substitute part of transition metal atoms are also included in the slurry as oxides, hydroxides, oxyhydroxides, nitrates, carbonates, dicarboxylates, fatty acid salts, ammonium salts, and the like. What is necessary is just to contain.

<Preparation of slurry>
As the solvent used for preparing the slurry, various organic solvents and aqueous solvents can be used, but water is preferred.

  In the present invention, a lithium compound, a transition metal compound, and other metal compounds used in combination as required are mixed with a solvent to obtain a slurry. Next, the slurry is preferably pulverized by a wet bead mill, a ball mill or the like. Alternatively, the solid raw material may be dry pulverized first and then mixed with a solvent to form a slurry.

  The slurry concentration is not particularly limited, and the lower limit of the concentration is usually 1% by weight or more, preferably 5% by weight or more, more preferably 10% by weight or more, and particularly preferably 20% by weight or more. When the slurry concentration is too low, productivity is lowered and the bulk density of particles obtained by spray drying tends to be reduced. The upper limit of the slurry concentration is usually 50% by weight or less. If the slurry concentration is too high, the viscosity of the slurry becomes high, and there is a possibility that it cannot be sprayed with a nozzle. The preferred slurry concentration is 45% by weight or less, particularly 40% by weight or less.

  The viscosity of the slurry is usually 100 mPs · s or more, preferably 300 mPs · s or more, and usually 2000 mPs · s or less, preferably 1500 mPs · s or less. If the viscosity of the slurry is too low, composition deviation tends to occur inside the droplets when sprayed, and if it is too high, it may not be possible to spray with a nozzle.

  The ratio of metals to each other in the slurry may be generally matched with the composition of the lithium transition metal composite oxide to be finally obtained, and is usually ± 20% with respect to the standard composition of the lithium transition metal composite oxide. Within 10%, preferably within ± 10%. The preferred atomic ratio of lithium to the sum of metals other than lithium in the slurry (ie, the sum of the transition metal and other metals optionally present to replace a portion of the transition metal) varies from transition metal to transition metal.

<Spray drying>
The prepared slurry of raw material compounds is subjected to spray drying.
The slurry is preferably spray-dried so that the average particle size of the resulting spray-dried powder is usually 1 μm or more, particularly 3 μm or more, and usually 100 μm or less, particularly 30 μm or less. The drying gas is preferably introduced into the spraying device at 80 to 300 ° C and discharged from the device at 45 to 250 ° C.

<Baking>
The obtained spray-dried powder is fired and converted into a lithium transition metal composite oxide.
The firing conditions are not particularly limited. For example, the methods described in JP-A-9-306490, JP-A-9-306493, JP-A-9-259880 and the like can be used. Suitable firing conditions depend on the composition of the lithium transition metal composite oxide and are as follows.

(1) Firing conditions of lithium manganese composite oxide In the present invention, after decarbonation firing by sufficiently holding at a temperature lower than the melting point (726 ° C.) of lithium carbonate, a temperature higher than the melting point of lithium carbonate, preferably It is desirable that the main firing is performed at a maximum temperature of 750 ° C. or higher because a dense lithium transition metal composite oxide can be produced.

  That is, in the production method of the present invention, first, the carbonic acid content of lithium carbonate is removed by maintaining the temperature at a temperature lower than the melting point of lithium carbonate, and then firing is performed at a temperature required for the solid-phase reaction. Thus, it is presumed that a dense lithium transition metal composite oxide can be produced.

  What temperature is set as the decarboxylation firing temperature of less than 726 ° C. and how long it is sufficient to hold at this temperature depends on the composition of the lithium transition metal composite oxide to be produced, but is usually as follows: Can be organized.

  The temperature lower than 726 ° C. is 720 ° C. or lower, preferably 710 ° C. or lower, and the lower limit is preferably 600 ° C. or higher, particularly 630 ° C. or higher.

  The decarbonation firing holding time may be longer when the temperature is low, and shorter when the temperature is higher, but is usually several hours or longer (ie 2 to 4 hours or longer), 5 hours or more, usually several days or less (that is, 2 to 4 days or less), especially 1 day or less.

  The main firing temperature for obtaining a lithium transition metal composite oxide (lithium manganese composite oxide) whose main transition metal is manganese is usually 750 ° C. or higher, usually 1000 ° C. or lower, preferably 950 ° C. or lower, particularly preferably. It is 900 degrees C or less. If the main firing temperature is too low, it is difficult to obtain a lithium manganese composite oxide with good crystallinity. On the other hand, if the main calcination temperature is too high, the lithium compound is diffused, so that the lithium manganese composite oxide having the target compound composition cannot be obtained.

  The main calcination time is usually 1 hour or longer, preferably 2 hours or longer, and is usually 100 hours or shorter, preferably 50 hours or shorter. If the firing time is too short, it is difficult to obtain a lithium-manganese composite oxide with good crystallinity. Conversely, it is meaningless to extend the firing time longer than necessary. The main firing time refers to the holding time at the main firing temperature.

  When the temperature is raised from room temperature to the firing temperature of the main firing or decarbonation firing described above, in order to carry out the reaction more uniformly, for example, the temperature is gradually raised at a temperature of 5 ° C. or less per minute, or once in the middle It is also preferable to stop the temperature increase and hold it at a constant temperature so that the entire temperature becomes uniform.

  In order to obtain a lithium-manganese composite oxide with few defects, it is preferable to cool slowly after the above-mentioned main firing, and gradually cool down to 700 ° C. or less, preferably up to 500 ° C. at a cooling rate of 100 ° C. or less per hour. It is preferable.

  The main baking or the decarbonation baking is usually performed in air, but can be performed by appropriately controlling the oxygen concentration. In addition, when baking in air, it is preferable to use air from which carbon dioxide has been previously removed.

The lithium manganese composite oxide produced by firing is basically a lithium manganate having a spinel structure having a reference composition of LiMn ₂ O ₄ or a lithium manganate having a layered structure having a reference composition of LiMnO ₂ . In particular, a lithium manganese composite oxide having a spinel structure is preferable.

(2) Firing Conditions for Layered Lithium Composite Oxide In the present invention, after decarbonation firing by sufficiently holding at a temperature lower than the melting point (726 ° C.) of lithium carbonate, a temperature higher than the melting point of lithium carbonate, preferably It is desirable that the main firing is performed at a maximum temperature of 750 ° C. or higher because a dense lithium transition metal composite oxide can be produced.

  That is, in the production method of the present invention, first, the carbonic acid content of lithium carbonate is removed by maintaining the temperature at a temperature lower than the melting point of lithium carbonate, and then firing is performed at a temperature required for the solid-phase reaction. Thus, it is presumed that a dense lithium transition metal composite oxide can be produced.

  What temperature is set as the decarboxylation firing temperature of less than 726 ° C. and how long it is sufficient to hold at this temperature depends on the composition of the lithium transition metal composite oxide to be produced, but is usually as follows: Can be organized.

  The temperature lower than 726 ° C. is 720 ° C. or lower, preferably 710 ° C. or lower, and the lower limit is preferably 600 ° C. or higher, particularly 630 ° C. or higher.

  The decarbonation firing holding time may be longer when the temperature is low, and shorter when the temperature is higher, but is usually several hours or longer (ie 2 to 4 hours or longer), 5 hours or more, usually several days or less (that is, 2 to 4 days or less), especially 1 day or less.

  The main firing temperature for obtaining a lithium transition metal composite oxide (layered lithium composite oxide) containing nickel, manganese and cobalt is usually 750 ° C. or higher, preferably 800 ° C. or higher, and usually 1200 ° C. or lower, preferably It is 1050 degrees C or less. If the main firing temperature is too low, it is difficult to obtain a layered lithium composite oxide having good crystallinity. In addition, when the main firing temperature is too high, a phase other than the target layered lithium composite oxide may be formed, or a layered lithium composite oxide having many defects may be formed.

  The main calcination time is usually 1 hour or longer, preferably 2 hours or longer, and is usually 100 hours or shorter, preferably 50 hours or shorter. If the main calcination time is too short, it is difficult to obtain a layered lithium composite oxide having good crystallinity. Conversely, a too long reaction time is industrially meaningless. The main firing time refers to the holding time at the main firing temperature.

  When the temperature is raised from room temperature to the firing temperature of the main firing or decarbonation firing described above, in order to carry out the reaction more uniformly, for example, the temperature is gradually raised at a temperature of 5 ° C. or less per minute, or once in the middle It is preferable to stop the temperature increase and keep the temperature constant so that the entire temperature becomes uniform.

  In addition, in order to obtain a layered lithium composite oxide with few defects, it is preferable to cool slowly after the above-mentioned main calcination, and gradually cool at a cooling rate of 600C or less, preferably 400C or less and 5C or less per minute. It is preferable to do.

  The main calcination or decarbonation calcination is usually performed in air, but can also be performed in other oxygen-containing gases. In addition, when baking in air, it is preferable to use air from which carbon dioxide has been previously removed.

  The heating device used for the firing of the lithium transition metal composite oxide of the present invention or the firing of the decarboxylation firing is not particularly limited as long as the above temperature and atmosphere can be achieved, regardless of the type and composition of the transition metal, For example, a box furnace, a tubular furnace, a tunnel furnace, a rotary kiln, etc. can be used.

<Physical properties of lithium transition metal composite oxide>
The lithium transition metal composite oxide obtained by the production method of the present invention is advantageous in that the tap density and the press density can be improved as compared with the prior art as shown below. The practical meaning of increasing the press density is to increase the electrode plate density when a positive electrode for a lithium secondary battery is produced by the method described later, and to increase the battery capacity per unit volume.

Tap density:
In the lithium manganese composite oxide, it is usually 1.6 g / cc or more, particularly 1.7 g / cc or more. The upper limit of the tap density is preferably as high as possible, but is usually about 1.8 g / cc or less.

  In the case of a layered lithium composite oxide, it can usually be 1.65 g / cc or more, particularly 1.7 g / cc or more. The upper limit of the tap density is preferably as high as possible, but is usually about 1.9 g / cc or less.

In addition, the tap density in this invention means the value measured using the Seishin company tap denser (KYT-400). That is, about 60 g of lithium transition metal composite oxide was put into a 100 cc graduated cylinder attached to the measuring machine, a tapping operation was performed with a stroke length of 20 mm, and the number of taps of 3000 times. Measure. The net weight (W) of the powder is measured by subtracting the tare weight of the graduated cylinder from the total weight, and the value calculated by the following equation 1 is called the tap density.
Tap density (g / cc) = W (g) / V (cc) Equation 1

Press density:
In the lithium manganese composite oxide, it can be usually 2 g / cc or more, particularly 2.1 g / cc or more. The upper limit of the press density is preferably as high as possible, but is usually about 2.3 g / cc or less.

  In the case of a layered lithium composite oxide, it is usually 2.3 g / cc or more, particularly 2.4 g / cc or more. The upper limit of the press density is preferably as high as possible, but is usually about 2.5 g / cc or less.

The press density in the present invention refers to a powder measurement unit (model; MCP-PD41) manufactured by Dia Instruments Co., Ltd., and 3.00 ± 0.0005 g of lithium transition metal composite oxide in an attached probe cylinder ( W) After charging and pressurizing the powder using a hydraulic jack, the pressure display meter shows the powder thickness (H) at 2000 kgf (pressure 400 kgf / cm ² = 39.2 MPa) using the attached linear scale. The value measured and calculated using Equation 2 below.
Press density (g / cc) = W (g) / [(2.5 / 2) ² × π × H (cm)] Equation 2

  Particle size: The average particle size of the lithium transition metal composite oxide of the present invention is usually 1 μm or more, particularly 3 μm or more, and usually 100 μm or less, particularly preferably 30 μm or less. The median diameter of the secondary particles is measured by setting a refractive index of 1.24 using a known laser diffraction / scattering particle size distribution apparatus. In the present invention, 0.1 wt% sodium hexametaphosphate aqueous solution was used for the measurement, and the measurement was performed after ultrasonic dispersion for 5 minutes.

[Positive electrode for lithium secondary battery]
The lithium transition metal composite oxide obtained by the production method of the present invention can be used as a positive electrode active material for a lithium secondary battery.

  The positive electrode is usually formed by forming an active material layer containing a positive electrode active material, a binder, and a conductive agent on a current collector. The active material layer can be usually obtained by preparing a slurry containing the above-described constituents, and applying, drying and pressing the slurry on a current collector. In the present invention, a lithium transition metal composite oxide produced by the method of the present invention is used as the positive electrode active material.

  The proportion of the lithium transition metal composite oxide in the active material layer is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, and usually 99.9% by weight or less, preferably 99% by weight. % Or less. If the proportion of the lithium transition metal composite oxide in the active material layer is too large, the strength of the positive electrode tends to be insufficient, and if it is too small, the capacity may be insufficient.

  Examples of the conductive agent used for the positive electrode include natural graphite, artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke. The proportion of the conductive agent in the active material layer is usually 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 1% by weight or more, and usually 50% by weight or less, preferably 20% by weight or less. More preferably, it is 10% by weight or less. If the proportion of the conductive agent in the active material layer is too large, the capacity may be insufficient, and if it is too small, the electrical conductivity may be insufficient.

  The binder used in the positive electrode includes not only fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and fluorine rubber, but also EPDM (ethylene-propylene-diene terpolymer). , SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose and the like. The ratio of the binder in the active material layer is usually 0.1% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more, and usually 80% by weight or less, preferably 60% by weight or less, more preferably. Is 40% by weight or less. When the ratio of the binder in the active material layer is too large, the capacity may be insufficient, and when it is too small, the strength may be insufficient.

  Moreover, as a solvent used when preparing the slurry for forming the active material layer of a positive electrode, the organic solvent which melt | dissolves or disperse | distributes a binder normally is used. For example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran and the like can be mentioned. In some cases, a dispersant, a thickener, or the like is added to water and slurried with a latex such as SBR.

  The thickness of the active material layer of the positive electrode is usually about 10 to 200 μm.

  As the material of the current collector used for the positive electrode, metals such as aluminum, stainless steel, nickel-plated steel, etc. are used, and preferably aluminum.

  Note that the active material layer obtained by applying and drying the slurry is usually used by compaction by a roller press or the like in order to increase the packing density of the electrode material.

[Lithium secondary battery]
The lithium secondary battery of the present invention usually has the positive electrode, the negative electrode, and the electrolyte.

  As the negative electrode material of the lithium secondary battery of the present invention, it is preferable to use a carbon material. Such carbon materials include natural or man-made graphite, petroleum coke, coal coke, petroleum pitch carbide, coal pitch carbide, phenolic resin / crystalline cellulose resin carbide, etc. Examples thereof include carbon materials, furnace black, acetylene black, pitch-based carbon fibers, PAN-based carbon fibers, or a mixture of two or more thereof.

These negative electrode materials are usually formed as an active material layer on a current collector together with a binder and, if necessary, a conductive agent.
In this case, the binder and the conductive agent that can be used for the negative electrode can be the same as those used for the positive electrode, and the formation of the active material layer of the negative electrode is the same as the method for forming the active material layer of the positive electrode. It can be done according to this.

  Moreover, lithium metal itself or lithium alloys, such as a lithium aluminum alloy, can also be used as a negative electrode.

  The thickness of the active material layer of the negative electrode is usually about 10 to 200 μm.

  As the material for the current collector of the negative electrode, metals such as copper, nickel, stainless steel, nickel-plated steel and the like are usually used, and copper is preferable.

  Examples of the electrolyte that can be used in the lithium secondary battery of the present invention include an electrolytic solution, a polymer solid electrolyte, and a semi-solid electrolyte.

  The electrolyte solution is preferably a non-aqueous electrolyte solution. Examples of the non-aqueous electrolyte include those obtained by dissolving various electrolytic salts in a non-aqueous solvent.

  As the non-aqueous solvent, for example, carbonates, ethers, ketones, sulfolane compounds, lactones, nitriles, halogenated hydrocarbons, amines, esters, amides, phosphate ester compounds, etc. may be used. it can. Typical examples of these are propylene carbonate, ethylene carbonate, chloroethylene carbonate, trifluoropropylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, vinylene carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, 1, 4-dioxane, 4-methyl-2-pentanone, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, Sulfolane, methyl sulfolane, acetonitrile, propionitrile, benzonitrile, butyronitrile, valeronitrile, 1,2-dichloroethane, dimethylformamide, dimethyl Sulfoxides, trimethyl phosphate, are alone or a mixture of two or more solvents such as triethyl phosphate may be used.

  Among the above non-aqueous solvents, it is preferable to use a high dielectric constant solvent in order to dissociate the electrolyte. The high dielectric constant solvent means a compound having a relative dielectric constant of about 20 or more at 25 ° C. Among the high dielectric constant solvents, it is preferable that the electrolyte solution contains ethylene carbonate, propylene carbonate, and compounds obtained by substituting hydrogen atoms thereof with other elements such as halogen or alkyl groups. When such a high dielectric constant solvent is used, the proportion of the high dielectric constant solvent in the electrolytic solution is usually 20% by weight or more, preferably 30% by weight or more, and more preferably 40% by weight or more. If the content of the high dielectric constant solvent is small, desired battery characteristics may not be obtained.

As the electrolytic salt, any conventionally known salt can be used, and LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , LiCl, LiBr, LiCH ₃ SO ₃ Li, LiCF ₃ SO ₃ , Examples thereof include lithium salts such as LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC (SO ₂ CF ₃ ) ₃ , and LiN (SO ₃ CF ₃ ) ₂ . These may be used alone or in combination of two or more.

In addition, addition of gas such as CO ₂ , N ₂ O, CO, SO ₂ , polysulfide Sx ²⁻ , vinylene carbonate, catechol carbonate and the like that produces a good film that enables efficient charge / discharge of lithium ions on the negative electrode surface The agent may be present in the electrolyte at an arbitrary ratio.

  Instead of the electrolytic solution, a polymer solid electrolyte that is a conductor of an alkali metal cation such as lithium ion can be used. Moreover, the semi-solid electrolyte which made the said electrolyte solution non-fluidized with the polymer can also be used.

  In the lithium secondary battery of the present invention, an electrolyte layer can be provided between the positive electrode and the negative electrode using various materials as described above.

  A separator is usually provided between the positive electrode and the negative electrode. As the separator, a microporous polymer film is used, and the material is nylon, polyester, cellulose acetate, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, tetrafluoroethylene, polypropylene, polyethylene, polybutene, etc. The polyolefin-type polymer | macromolecule can be mentioned. Moreover, a nonwoven fabric filter such as glass fiber, a composite nonwoven fabric filter of glass fiber and polymer fiber, and the like can also be used. The chemical and electrochemical stability of the separator is an important factor, and from this point, the polymer is preferably a polyolefin polymer, and in particular, it is made of polyethylene from the viewpoint of the self-blocking temperature, which is one of the purposes of the battery separator. Preferably there is.

  In the case of a polyethylene separator, ultrahigh molecular weight polyethylene is preferable from the viewpoint of maintaining high-temperature shape, and the lower limit of the molecular weight is preferably 500,000, more preferably 1,000,000, and most preferably 1.5 million. On the other hand, the upper limit of the molecular weight is preferably 5 million, more preferably 4 million, and most preferably 3 million. This is because if the molecular weight is too large, the pores of the separator may not be blocked when heated because the fluidity is too low.

  Examples The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

<Example 1>
61.43 kg of water was placed in a slurry preparation tank, 20 kg of self-produced dimanganese trioxide (Mn ₂ O ₃ ) burned at 850 ° C. with MnO ₂ (manufactured by Tosoh), lithium hydroxide monohydrate (Honjo Chemical Co., Ltd.) 4.412 kg (105.2 mol), lithium carbonate (Honjo Chemical Co., Ltd.) 1.295 kg (17.5 mol), and boehmite (AlOOH, Condia Co., Ltd., trade name PURAL200) 0.97 kg were added. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 740 mPa · s.

The ratio (Ω) of Li derived from lithium carbonate in the total Li in this slurry can be calculated by the following formula 3.
Ω = lithium amount derived from lithium carbonate (mol) / total lithium amount Equation 3

In this example, Ω is 25 mol% as described below.
Ω = lithium amount derived from lithium carbonate (mol) / total lithium amount = number of moles of lithium carbonate × 2 / (number of moles of lithium hydroxide + number of moles of lithium carbonate × 2) × 100
= 17.5 × 2 / (105.2 + 17.5 × 2) × 100
= 25 mol%

  Next, the slurry is sprayed using a spray dryer (Fujisaki Electric Co., Ltd., Micro Mist Dryer MDP-50, nozzle type is equipped with a circle edge nozzle), a dry air temperature of 105 ° C., a slurry supply rate of 0.56 L / min, Spray-dried powder was obtained by spray-drying under the condition of a spray air amount of 1200 L / min. The obtained spray-dried powder was held at 600 ° C. for 6 hours and then calcined at 900 ° C. for 8 hours. The baked product was fitted with a sieve having an opening of 45 μm (diameter 20 cm), and pulverization classification was carried out for 1 hour using a vibrating sieve containing 25 Teflon-coated iron balls 15 mm in diameter.

The sieving powder (W1) was 910 g, and the sieving powder (W2) was 19 g. Therefore, the under-sieving yield defined by the following formula 4 was 98.0% by weight.
Yield under sieve (wt%) = W1 / (W1 + W2) × 100 Equation 4

  The specific surface area, tap density, and press density of the lithium manganese composite oxide thus obtained were evaluated by the following methods, and the results are shown in Table 1. The average particle size of the lithium manganese composite oxide was 10.1 μm.

Specific surface area:
A specific surface area measuring device (Shimadzu Corporation Micromeritics, Flowsorb II2300) was used for evaluation by a predetermined operation.

Tap density:
It measured using the Seisen company tap denser (KYT-400). The measuring method is shown below.
About 60 g of the sample was put into the attached 100 cc graduated cylinder, and the tapping operation was performed with a stroke length of 20 mm and a tap count of 3000 times. After the tapping was completed, the powder volume in the graduated cylinder was read and found to be 34 cc (V). The net weight of the powder was measured by subtracting the tare weight of the graduated cylinder from the total weight of 109.2 g. In this measurement, it was 60 g (W). The tap density (g / cc) was measured from the volume (V) of the powder and the weight (W) of the powder using the following formula.
Tap density (g / cc) = W (g) / V (cc) Equation 1

Press density:
Measured using a powder measurement unit (model; MCP-PD41) manufactured by Dia Instruments Co., Ltd. 3.000 ± 0.0005 g (W) of the sample was placed in the attached probe cylinder and pressurized using a hydraulic jack. The sample powder thickness (H) at a pressure display meter of 2000 kgf (pressure 400 kgf / cm ² = 39.2 MPa) was measured using an attached linear scale. Since the diameter of the probe cylinder was 2.5 cm, the press density was measured using the following formula 2.
Press density (g / cc) = W (g) / [(2.5 / 2) ² × π × H (cm)] Equation 2

  Further, when a cross-sectional SEM photograph of the prepared lithium manganese composite oxide filled and solidified with a resin was taken and observed, it was confirmed that the inside of the particles had a solid structure as shown in FIG.

<Example 2>
61.84 kg of water was placed in a slurry preparation tank, and 20 kg of dimanganese trioxide prepared by baking MnO ₂ (manufactured by Tosoh) at 850 ° C. and 2.941 kg of lithium hydroxide monohydrate (manufactured by Honjo Chemical Co., Ltd.) 70.1 mol), lithium carbonate (Honjo Chemical Co., Ltd.) 2.591 kg (35.1 mol), and boehmite (AlOOH, Condia Co., Ltd., trade name PURAL200) 0.97 kg were charged. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 940 mPa · s.
The Ω of this slurry was 50 mol% according to Formula 3.

  Next, this slurry was spray-dried in the same manner as in Example 1, and the obtained spray-dried powder was fired under the same conditions as in Example 1 to obtain a lithium manganese composite oxide.

  For this lithium manganese composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 were as shown in Table 1. The average particle size of the lithium manganese composite oxide was 9.4 μm.

<Comparative Example 1>
61.18 kg of water was placed in a slurry preparation tank, and 20 kg of dimanganese trioxide prepared by baking MnO ₂ (manufactured by Tosoh) at 850 ° C. and 5.341 kg of lithium hydroxide monohydrate (manufactured by Honjo Chemical Co., Ltd.) 127.3 mol) and boehmite (AlOOH, manufactured by Condia, trade name PURAL200) 0.97 kg were added. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 1550 mPa · s.
The Ω of this slurry was 0 mol% from Formula 3.

  Next, this slurry was spray-dried in the same manner as in Example 1, and the obtained spray-dried powder was fired under the same conditions as in Example 1 to obtain a lithium manganese composite oxide.

  For this lithium manganese composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 were as shown in Table 1. The average particle size of the lithium manganese composite oxide was 10.0 μm.

  Further, when the prepared lithium manganese composite oxide was filled and solidified with a resin, a cross-sectional SEM photograph was taken and observed, and as shown in FIG. 2, the inside of the particle was confirmed to have a hollow structure.

<Comparative example 2>
61.43 kg of water was placed in a slurry preparation tank, and 20 kg of dimanganese trioxide prepared by baking MnO ₂ (manufactured by Tosoh Corp.) at 850 ° C. and 1.471 kg of lithium hydroxide monohydrate (manufactured by Honjo Chemical Co., Ltd.) 35.1 mol), 3.886 kg (52.6 mol) of lithium carbonate (Honjo Chemical Co., Ltd.) and 0.97 kg of boehmite (AlOOH, manufactured by Condia, Inc., trade name PURAL200) were added. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 1300 mPa · s.
The Ω of this slurry was 75 mol% according to Formula 3.

  Next, this slurry was spray-dried in the same manner as in Example 1, and the obtained spray-dried powder was fired under the same conditions as in Example 1 to obtain a lithium manganese composite oxide.

  For this lithium manganese composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 are as shown in Table 1, and the tap density and press by adding lithium carbonate. There was no improvement in density. The average particle size of the lithium manganese composite oxide was 8.4 μm.

<Comparative Example 3>
61.43 kg of water was placed in a slurry preparation tank, and 20 kg of manganic trioxide prepared by baking MnO ₂ (manufactured by Tosoh) at 850 ° C. and 3.886 kg (52.6 mol) of lithium carbonate (manufactured by Honjo Chemical Co., Ltd.) And 0.97 kg of boehmite (AlOOH, manufactured by Condia, trade name PURAL200) was added. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 1300 mPa · s.
The Ω of this slurry was 100 mol% from Formula 3.

  Next, this slurry was spray-dried in the same manner as in Example 1, and the obtained spray-dried powder was fired under the same conditions as in Example 1 to obtain a lithium manganese composite oxide.

  With respect to this lithium manganese composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 were as shown in Table 1, and the tap density and press density were low.

<Example 3>
64.57 kg of water is placed in the slurry preparation tank, and 8.900 kg of NiO (manufactured by Shodo Chemical), 3.433 kg of Co (OH) ₂ (manufactured by Ise Chemical), and MnO ₂ (manufactured by Tosoh) are baked at 850 ° C. 2.166 kg of self-made Mn ₂ O ₃ , lithium hydroxide monohydrate (Honjo Chemical Co., Ltd.) 7.656 Kg (182.5 mol), lithium carbonate (Honjo Chemical Co., Ltd.) 0.355 kg (4.8 mol) I put it in. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 240 mPa · s.
The Ω of this slurry was 5 mol% according to Formula 3.

  Next, the slurry is sprayed using a spray dryer (Fujisaki Electric Co., Ltd., Micro Mist Dryer MDP-50, nozzle type is equipped with a circle edge nozzle), a dry air temperature of 105 ° C., a slurry supply rate of 0.56 L / min, Spray-dried powder was obtained by spray-drying under the condition of a spray air amount of 1800 L / min. The obtained spray-dried powder was held at 600 ° C. for 6 hours and then calcined at 845 ° C. for 8 hours to obtain a layered lithium composite oxide.

  For this layered lithium composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 were as shown in Table 2. The average particle size of the layered lithium composite oxide was 9.3 μm.

<Example 4>
64.29 kg of water is placed in the slurry preparation tank, and 8.900 kg of NiO (manufactured by Shodo Chemical), 3.433 kg of Co (OH) ₂ (manufactured by Ise Chemical), and MnO ₂ (manufactured by Tosoh) are baked at 850 ° C. 2.166 kg of self-made Mn ₂ O ₃ , lithium hydroxide monohydrate (Honjo Chemical Co., Ltd.) 6.850 Kg (163.3 mol), lithium carbonate (Honjo Chemical Co., Ltd.) 1.064 kg (14.4 mol) I put it in. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 370 mPa · s.
The Ω of this slurry was 15 mol% according to Formula 3.

  Next, this slurry was spray-dried in the same manner as in Example 3, and the obtained spray-dried powder was fired under the same conditions as in Example 3 to obtain a layered lithium composite oxide.

  For this layered lithium composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 were as shown in Table 2. The average particle size of the layered lithium composite oxide was 7.1 μm.

<Example 5>
64.02 kg of water is placed in the slurry preparation tank, and 8.900 kg of NiO (manufactured by Shodo Chemical), 3.433 kg of Co (OH) ₂ (manufactured by Ise Chemical), and MnO ₂ (manufactured by Tosoh) are baked at 850 ° C. 2.166 kg of self-produced Mn ₂ O ₃ , lithium hydroxide monohydrate (Honjo Chemical Co., Ltd.) 6.044 Kg (144.1 mol), lithium carbonate (Honjo Chemical Co., Ltd.) 1.774 kg (24.0 mol) I put it in. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 370 mPa · s.
The Ω of this slurry was 25 mol% according to Formula 3.

  Next, this slurry was spray-dried in the same manner as in Example 3, and the obtained spray-dried powder was fired under the same conditions as in Example 3 to obtain a layered lithium composite oxide.

  For this layered lithium composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 were as shown in Table 2. The average particle size of the layered lithium composite oxide was 7.3 μm.

<Example 6>
63.32 kg of water is placed in the slurry preparation tank, and 8.900 kg of NiO (manufactured by Shodo Chemical), 3.433 kg of Co (OH) ₂ (manufactured by Ise Chemical), and MnO ₂ (manufactured by Tosoh) are baked at 850 ° C. 2.166 kg of self-produced Mn ₂ O ₃ , lithium hydroxide monohydrate (Honjo Chemical Co., Ltd.) 4.030 Kg (96.1 mol), lithium carbonate (Honjo Chemical Co., Ltd.) 3.548 kg (48.0 mol) I put it in. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 370 mPa · s.
The Ω of this slurry was 50 mol% according to Formula 3.

  Next, this slurry was spray-dried in the same manner as in Example 3, and the obtained spray-dried powder was fired under the same conditions as in Example 3 to obtain a layered lithium composite oxide.

  For this layered lithium composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 were as shown in Table 2.

<Comparative example 4>
64.70 kg of water is placed in the slurry preparation tank, and NiO (manufactured by Shodo Chemical Co., Ltd.) 8.900 Kg, Co (OH) ₂ (manufactured by Ise Chemical Co., Ltd.) 3.433 Kg, and MnO ₂ (manufactured by Tosoh Corp.) are fired at 850 ° C. Then, 2.166 kg of self-produced Mn ₂ O ₃ and 8.059 Kg (192.2.1 mol) of lithium hydroxide monohydrate (Honjo Chemical Co., Ltd.) were added. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 330 mPa · s.
The Ω of this slurry was 0 mol% from Formula 3.

  Next, this slurry was spray-dried in the same manner as in Example 3, and the obtained spray-dried powder was fired under the same conditions as in Example 3 to obtain a layered lithium composite oxide.

  For this layered lithium composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 were as shown in Table 2. The average particle size of the layered lithium composite oxide was 9.2 μm.

<Comparative Example 5>
64.70 kg of water is placed in the slurry preparation tank, and 8.900 kg of NiO (manufactured by Shodo Chemical), 3.433 kg of Co (OH) ₂ (manufactured by Ise Chemical), and MnO ₂ (manufactured by Tosoh) are baked at 850 ° C. Then, 2.166 kg of self-produced Mn ₂ O ₃ and 8.059 Kg (192.2.1 mol) of lithium hydroxide monohydrate (Honjo Chemical Co., Ltd.) were added. This was subjected to wet bead mill pulverization for 3 hours under stirring to prepare a slurry having a viscosity of 1120 mPa · s.
The Ω of this slurry was 100 mol% from Formula 3.

  Next, this slurry was spray-dried in the same manner as in Example 3, and the obtained spray-dried powder was fired under the same conditions as in Example 3 to obtain a layered lithium composite oxide.

  For this layered lithium composite oxide, the sieving yield, specific surface area, tap density, and press density obtained in the same manner as in Example 1 are as shown in Table 2, and an improvement in tap density was observed. The density decreased.

  The relationship between Ω and tap density, and Ω and press density in Examples 1 and 2 and Comparative Examples 1 to 3 shown in Table 1 is shown in FIG. 3, and Examples 3 to 6 and Comparative Example 4 shown in Table 2 are shown in Table 2. FIG. 4 shows the relationship between Ω and tap density of 5, and Ω and press density.

  As is apparent from FIGS. 3 and 4, both tap density and press density are high in the range of Ω of Examples 1 to 6 according to the present invention. This result suggests the possibility of improving the battery capacity per volume of the lithium ion secondary battery in practice.

  The application of the lithium secondary battery to which the present invention is applied is not particularly limited, and can be used for various known applications. Specific examples include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, and transceivers. Electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, lighting equipment, toys, game machines, watches, strobes, cameras, automobile power sources, and the like.

It is a cross-sectional SEM photograph of what filled and solidified the lithium manganese complex oxide manufactured in Example 1 with resin. It is a cross-sectional SEM photograph of what filled and solidified the lithium manganese complex oxide manufactured by the comparative example 1 with resin. It is a graph which shows the relationship between (omega | ohm) and tap density in Example 1, 2 and Comparative Examples 1-3, (omega | ohm), and a press density. It is a graph which shows the relationship between (omega) and tap density in Examples 3-6 and Comparative Examples 4 and 5, and (omega) and press density.

Claims (7)

  In a method for producing a lithium transition metal composite oxide by spray drying a slurry containing a manganese compound and a lithium compound, and then firing the slurry, the lithium compound includes lithium hydroxide and lithium carbonate, and the lithium carbonate with respect to all Li atoms is converted into lithium carbonate. A method for producing a lithium transition metal composite oxide, wherein the proportion of derived Li atoms is 10 to 60 mol%.   In a method for producing a lithium transition metal composite oxide by spray drying a slurry containing a manganese compound, a cobalt compound, a nickel compound, and a lithium compound, and then firing the slurry, the lithium compound includes lithium hydroxide and lithium carbonate, A method for producing a lithium transition metal composite oxide, wherein the ratio of Li atoms derived from lithium carbonate to all Li atoms is 5 to 95 mol%.   2. The method for producing a lithium transition metal composite oxide according to claim 1, wherein the slurry further contains an aluminum compound.   4. The method for producing a lithium transition metal composite oxide according to claim 1, wherein after the slurry is spray-dried, the slurry is sufficiently held at a temperature lower than the melting point of lithium carbonate (726 ° C.), and then the carbonic acid is continuously added. A method for producing a lithium transition metal composite oxide, comprising firing at a temperature equal to or higher than a melting point of lithium.   The lithium transition metal complex oxide manufactured by the manufacturing method of any one of Claims 1 thru | or 4.   A positive electrode for a lithium secondary battery, comprising the lithium transition metal composite oxide according to claim 5 and a binder.   The lithium secondary battery which has the positive electrode for lithium secondary batteries of Claim 6, the negative electrode which can occlude / release lithium ion, and an electrolyte.

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