JP2003119029A - METHOD OF PRODUCING Mn203, AND METHOD OF PRODUCING LITHIUM-MANGANESE COMPOUND OXIDE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing the intrusion of iron into a battery material, and preventing the intrusion of SUS powder into a battery as well. SOLUTION: In the method of producing Mn2 O3 , MnO2 is allowed to pass through the magnetic field of 100 to 3,200 Gs, and is thereafter burned.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing Mn ₂ O _{3 and} a method for producing a lithium manganese composite oxide, and further to a lithium manganese composite oxide produced by the production method and the lithium manganese composite oxide. And a method for removing metal powder from MnO ₂ .

[0002]

2. Description of the Related Art In recent years, various devices such as a VTR device with a built-in camera, an audio device, a portable computer, and a mobile phone have been reduced in size and weight, and a demand for higher performance of a battery as a power source of these devices has been increased. Is increasing. In order to meet the demand, various developments have been made. For example, by using a carbon material or the like capable of inserting and extracting lithium ions as a negative electrode active material in place of metallic lithium, safety is significantly improved, and lithium The next battery has entered the practical stage.

On the other hand, as a positive electrode active material for lithium secondary batteries, lithium transition metal composite oxides such as LiCoO ₂ , LiNiO ₂ and LiMn ₂ O ₄ are in the practical stage. In particular, a manganese-based positive electrode active material composed of a lithium manganese composite oxide such as LiMn ₂ O ₄ has a large amount of reserves of manganese as a component compared with cobalt and nickel, and is inexpensive. It also has the advantage of being highly reliable.

The above lithium-manganese composite oxide can be manufactured by mixing and firing a lithium compound and a manganese compound. From the viewpoint of having a valence close to the manganese oxidation number of the final target compound oxide, the viewpoint of being inexpensively available as an industrial raw material, and the viewpoint of high reactivity, the manganese compound is Mn ₂ O. ₃ is particularly preferred. Mn ₂ O ₃ is usually produced by heat treating MnO ₂ . However, MnO ₂ which is generally distributed has a metal (iron) as a foreign substance,
In addition, SUS powder or the like may be mixed in the crushing process. This is particularly remarkable in the case of electrolytic MnO ₂ .

In general, a battery is manufactured by applying a battery material as described above to a current collector to manufacture an electrode plate and assembling them into a battery. However, iron derived from raw materials in the manufacturing process of battery materials, and iron powder may be mixed in the manufacturing process,
When iron is mixed in the battery material, it is considered that the iron causes a micro short circuit, and the battery loses its function as a battery. Further, in some cases, SUS powder may be mixed in the manufacturing process, and in that case, it is considered that SUS powder in the battery material causes a micro short circuit, and the battery loses its function as a battery.

[0006]

Therefore, there has been a demand for a method of preventing iron from being mixed into a battery material. Further, there has been a demand for a method of preventing SUS powder from being mixed into the battery material.

[0007]

The present inventors have SUMMARY OF THE INVENTION As a result of extensive investigations to solve the above problems, foreign materials prior to firing the MnO _2, by passing a magnetic field of predetermined flux density in the MnO ₂ As a result, they have found that they can remove only the metal, and have solved the present invention. That is, the gist of the present invention lies in the following (1) to (10).

(1) MnO ₂ is 100 gauss or more, 3
A method for producing Mn ₂ O ₃ , which comprises firing after passing a magnetic field of less than 200 Gauss. (2) MnO ₂ is passed through a magnetic field of 100 Gauss or more and less than 3200 Gauss and then calcined to obtain Mn ₂ O ₃ , and then Mn ₂ O ₃ is mixed with a thium compound and then calcined. And a method for producing a lithium manganese composite oxide.

(3) MnO ₂ is 100 Gauss or more, 3
After passing through a magnetic field of less than 200 Gauss, it is fired and Mn ₂
A method for producing a lithium-manganese composite oxide, characterized in that O ₃ is obtained, and then Mn ₂ O ₃ is mixed with a lithium compound in a solvent to obtain a slurry, and the slurry is spray-dried and then calcined. (4) The manufacturing method according to any one of (1) to (3), wherein the lower limit of the magnetic flux density of the magnetic field is 700 gauss or more.

(5) The mixing ratio of the lithium compound and MnO ₂ is Li / Mn = 0.4-in terms of Li atom and Mn atom.
The production method according to any one of (2) to (4) above, wherein the quantity ratio is 0.6. (6) The production method according to any of (2) to (5) above, wherein a compound containing a metal element other than lithium and manganese is mixed in a solvent in addition to MnO ₂ and a lithium compound.

(7) The mixing ratio of the compound containing a metal element (hereinafter referred to as "other metal") other than lithium and manganese is M
In terms of n atoms and other metal atoms, the other metal element is 2.5 with Mn.
The production method according to (6) above, wherein the amount ratio is about 30 mol%. (8) The lithium manganese composite oxide

[0012]

Embedded image Li _b Mn _2-a Me _a O ₄ (Me is B, Al, Sn, Cu, Ti, Zn, Co, N
represents at least one selected from the group consisting of i, and 0 ≦
The production method according to any one of (2) to (7) above, wherein b ≦ 1.5 and 0 <a ≦ 1).

(9) A lithium manganese composite oxide produced by the production method described in any of (2) to (8) above. (10) A lithium secondary battery having a positive electrode, a negative electrode, and an electrolyte containing the lithium-manganese composite oxide produced by the production method according to any one of (2) to (8) above.

(11) MnO ₂ of 100 Gauss or more,
Metal dust removing method from MnO _2, characterized in that passing the magnetic field of less than 3200 gauss.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing Mn ₂ O ₃ of the present invention comprises:
(1) It is characterized in that MnO ₂ is fired after passing a magnetic field of 100 Gauss or more and less than 3200 Gauss. The method for producing a lithium-manganese composite oxide according to the present invention includes (2) MnO ₂ of 100 gauss or more, 320
0 calcined after passing through a magnetic field of less than Gauss give Mn ₂ O _3, then the and mixed Mn ₂ O ₃ and lithium compound and then and firing.

Further, according to the present invention, lithium manganese complex acid is used.
(3) MnO₂Over 100 gauss
Above, after passing through a magnetic field of less than 3200 gauss
Mn ₂O₃And then the Mn₂O₃With a lithium compound
Mix under a solvent to obtain a slurry, and spray-dry the slurry.
And then fired. In addition, "solvent
"Lower" means "in the presence of a solvent" or "with a solvent"
Is the meaning.

In the present invention, "passing a magnetic field" includes bringing an object having a magnetic field into contact. In the present invention, it is easier to remove the metal as a foreign substance by bringing it into contact with an object having a magnetic field. In the present invention, before firing, MnO
_The reason why ₂ is passed through the above-mentioned magnetic field is that the metal as a foreign substance is taken into the particles of Mn ₂ O ₃ after firing, and it becomes difficult to remove only the metal as a foreign substance. The term "calcination" as used herein means that MnO ₂ is heat-treated to M
It means firing when preparing n ₂ O ₃ .

In the present invention, the strength of the magnetic field for passing MnO ₂ is 100 Gauss or more and less than the magnetic flux density at which MnO ₂ is attracted. If the magnetic flux density is too low, the metal as a foreign substance cannot be removed. If the magnetic flux density is too high, MnO ₂ is also removed. If the magnetic flux density is 100 gauss or more, it is sufficient to remove iron as a foreign matter, but preferably 2
00 gauss or more, more preferably 400 gauss or more, and further preferably 70 from the viewpoint of removing SUS powder.
It is 0 gauss or more, and most preferably 1000 gauss or more. Further, the magnetic flux density must be less than the magnetic flux density MnO ₂ is sucked, preferably not more than low flux density 100 Gauss or higher than the magnetic flux density MnO ₂ is sucked. The magnetic flux density at which MnO ₂ is attracted is specifically 32
It is 00 gauss.

The "magnetic flux density at which the compound is attracted" in the present invention means the "minimum magnetic force density required to attract the compound to the magnet". MnO
_2, 100 gauss, in order to pass through the magnetic field of less than the magnetic flux density MnO ₂ is sucked, for example, areas for passing the MnO ₂ "100 gauss, magnetic field less than the magnetic flux density MnO ₂ is sucked" The magnet may be arranged so as to give That is, the strength of the magnets may be arbitrarily selected and the arrangement of the magnets may be designed so that the above area is formed. In addition, MnO is given to a substance (for example, a magnet) that gives “a magnetic field of 100 Gauss or more and less than the magnetic flux density at which MnO ₂ is attracted”
_The device may be designed so that the _two are in contact.

In the present invention, the MnO _2, 100 gauss, but MnO ₂ to produce a Mn ₂ O ₃ by firing after passing through a magnetic field of less than the magnetic flux density to be sucked, Mn ₂
O ₃ can be obtained by heating MnO ₂ at a temperature of 400 ° C. or higher and 950 ° C. or lower. The atmosphere for the heat treatment may be any of the atmosphere, oxygen and inert gas, but the atmosphere is preferred from the viewpoint of the structure of the firing furnace. The heat treatment temperature can be lowered within the above heating temperature range by coexisting in an inert gas such as nitrogen or with a reducing agent such as carbon.

The lithium compounds used as starting materials in the method for producing a lithium-transition metal composite oxide in the present invention include Li ₂ CO ₃ , LiNO ₃ and LiO.
H, LiOH / H ₂ O, LiCl, LiI, CH ₃ COO
Examples thereof include Li, Li ₂ O, Li acetate, Li dicarboxylic acid, Li citric acid, Li fatty acid, alkyl lithium, and lithium halide. Preferred among these lithium _{compounds, Li 2 CO 3, LiNO 3} , LiOH · H 2
It is a water-soluble lithium compound such as O and Li acetate. By dissolving these water-soluble compounds in a slurry using water as a dispersion medium, for example, a lithium-transition metal composite oxide having good properties can be easily obtained. Further, a lithium compound containing no nitrogen atom or sulfur atom is preferable because it does not generate harmful substances such as NO _X and SO _X during the firing treatment. The most preferable lithium raw material is LiOH.H ₂ O, which is also water-soluble and does not contain a nitrogen atom or a sulfur atom. Of course, plural kinds of lithium compounds may be used.

As the lithium-manganese composite oxide in the present invention, typically lithium manganate having a spinel structure having LiMn ₂ O ₄ as a basic composition and basic composition LiM.
Although a lithium manganate having a layered structure containing nO ₂ can be mentioned, a spinel type lithium manganate is preferable from the viewpoint of ease of production and cycle characteristics. The lithium-manganese composite oxide may further contain other elements in addition to lithium, manganese and oxygen. B, A
Metal elements such as 1, Sn, Cu, Ti, Zn, Co and Ni can be mentioned, but Al is preferable. That is, in a preferred embodiment, the lithium-manganese composite oxide is a composite oxide containing lithium, manganese and aluminum. Such other element has a function of stabilizing the crystal structure, for example, by substituting a part of the manganese site with the other element. As the substitution element for the manganese site, B,
Metal elements such as Al, Sn, Cu, Ti, Zn, Co and Ni can be mentioned. Of course, a plurality of elements can be substituted. The preferred substituting element is Al. Further, a part of oxygen atoms can be replaced with a halogen element such as fluorine.

Such another element substitution type lithium manganese composite oxide is usually used in the case of a spinel structure lithium manganese composite oxide.

[0024]

Embedded image Li _b Mn _2-a Me _a O ₄ (Me is B, Al, Sn, Cu, Ti, Zn, Co, N
represents at least one selected from the group consisting of i, and 0 ≦
It can be represented by a composition of b ≦ 1.5 and 0 <a ≦ 1).
Here, the preferable substitution element Me is Al. However,
The type and composition ratio of the substituting element are not limited to these as long as the crystal structure can be stabilized.
Particularly preferred composition of lithium manganese composite oxide is

[0025]

Embedded image Li _Y Mn _2-X Al _X O ₄ (0 <X ≦ 1.0, 0.9 ≦ Y ≦ 1.1).

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 substitute a part of the manganese atom sites with lithium by using, for example, a stoichiometric amount or more of lithium as a raw material. For example, in the production method of the present invention, in addition to the lithium compound and MnO _2, a compound containing a metal element other than lithium and manganese (hereinafter sometimes referred to as “other metal”) is mixed with the lithium compound and MnO _{2 in a} solvent. By doing so, a lithium-manganese composite oxide in which a part of manganese is replaced with another metal element can be obtained.

The compounds of other metal elements include oxides, hydroxides, nitrates, carbonates, dicarboxylic acid salts, fatty acid salts,
Examples thereof include ammonium salts. These starting materials are
Usually, they are mixed by wet mixing. A step of grinding may be added before and after mixing and during mixing. As the solvent used in the present invention, various organic solvents and aqueous solvents can be used, but water is preferable.

As a method for firing and cooling the lithium manganese oxide, for example, 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 speed, a method of calcination, a main firing in 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 / cooling conditions are described in detail in JP-A-9-306490, JP-A-9-306493, JP-A-9-259880 and the like.

In the above, the lithium compound and MnO ₂
The mixing ratio is usually Li / Mn in terms of Li atom and Mn atom.
= 0.4 to 0.6, preferably 0.45 to 0.55, and more preferably 0.5 to 0.55. Li
If the amount is too large or too small, a sufficient capacity cannot be obtained. When the lithium-manganese composite oxide is another element-substitution type lithium-manganese composite oxide, a starting material is a compound containing a metal element (substitution element) other than lithium and manganese, in addition to the lithium compound and MnO _2. Mix. The mixing ratio of the compound containing a metal element other than manganese is 2.5 mol% or more of Mn, preferably 5 mol% or more of Mn, in terms of Mn atoms and metal atoms other than manganese. , Usually 30 mol% of Mn
Hereafter, it is preferably 20 mol% or less of Mn. 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 above-mentioned quantitative ratio (Li / Mn) is the quantitative ratio of Li / (Mn + metal atoms other than manganese). (That is, the mixing ratio of lithium compound and manganese compound: Li atom, Mn atom, and metal atom other than manganese is usually Li / (Mn + metal atom other than manganese) = 0.4 to 0.6, preferably 0.45 to 0.45. 0.55, more preferably 0.5 to 0.55
The amount ratio of the lithium manganese composite oxide of the present invention can be used as an active material of a positive electrode of a lithium secondary battery.

The positive electrode is usually formed by forming an active material layer containing the above positive electrode material, a binder and a conductive agent on a current collector. In the present invention, the positive electrode active material is a lithium manganese composite oxide. The active material layer can be usually obtained by preparing a slurry containing the above-mentioned constituents, applying this on a current collector, and drying. The proportion of the positive electrode material of the present invention 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, usually 9
It is 9.9% by weight or less, preferably 99% by weight or less.
If the amount of the positive electrode material 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 ratio of the conductive agent in the active material layer is usually 0.01.
The content is at least wt%, preferably at least 0.1 wt%, more preferably at least 1 wt%, usually at most 50 wt%, preferably at most 20 wt%, more preferably at most 10 wt%. If the amount of the conductive agent is too large, the capacity may be insufficient, and if it is too small, the electrical conductivity may be insufficient.

Further, as the binder used for the positive electrode,
Polyvinylidene fluoride, polytetrafluoroethylene,
In addition to fluoropolymers such as fluorinated polyvinylidene fluoride and fluororubber, EPDM (ethylene-propylene-diene terpolymer), SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber),
Examples thereof include polyvinyl acetate, polymethylmethacrylate, polyethylene, nitrocellulose and the like. The proportion 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, usually 80% by weight or less, preferably 60% by weight or less, More preferably, it is 40% by weight or less. If it is too large, the capacity may be insufficient, and if it is too small, the strength may be insufficient.

As the solvent used when preparing the slurry, an organic solvent that dissolves or disperses the binder is usually used. Examples thereof include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N-dimethylaminopropylamine, ethylene oxide and tetrahydrofuran. In addition, a dispersant, a thickener, etc. may be added to water to form a slurry with a latex such as SBR.

The thickness of the active material layer is usually 10 to 200 μm.
It is a degree. As a material of the current collector used for the positive electrode, a metal such as aluminum, stainless steel, nickel-plated steel is used, and aluminum is preferable. The active material layer obtained by coating and drying is preferably consolidated by a roller press or the like in order to increase the packing density of the electrode material.

The lithium secondary battery of the present invention usually has the above-mentioned positive electrode, negative electrode and non-aqueous electrolyte solution. As the negative electrode material that can be used in the lithium secondary battery of the present invention, it is preferable to use a carbon material. As such a carbon material,
Natural or artificial graphite, petroleum-based coke, coal-based coke, petroleum-based pitch carbide, coal-based pitch carbide, phenolic resin / crystalline cellulose or other resin carbide and carbon material obtained by partially carbonizing them, furnace black, acetylene black , Pitch-based carbon fibers, PAN-based carbon fibers, or a mixture of two or more thereof. The negative electrode material is usually formed as an active material layer on the current collector together with the binder and, if necessary, the conductive agent. Also,
It is also possible to use lithium metal itself or a lithium alloy such as a lithium aluminum alloy as the negative electrode. Examples of the binder and conductive agent that can be used for the negative electrode include those similar to those used for the positive electrode.

The thickness of the active material layer of the negative electrode is usually 10 to 20.
It is about 0 μm. The formation of the negative electrode active material layer can be performed according to the method for forming the positive electrode active material layer. As a material for the current collector of the negative electrode, a metal such as copper, nickel, stainless steel, or nickel-plated steel is usually used, and copper is preferable. Examples of the non-aqueous electrolytic solution that can be used in the lithium secondary battery of the present invention include various electrolytic salts dissolved in a non-aqueous solvent.

As the non-aqueous solvent, for example, carbonates, ethers, ketones, sulfolane compounds, lactones, nitriles, halogenated hydrocarbons, amines, esters, amides, phosphoric acid ester compounds and the like are used. can do. To list these representative ones, propylene carbonate, ethylene carbonate,
Chloroethylene carbonate, trifluoropropylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, ethylmethyl 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, methylsulfolane, acetonitrile, propionitrile, benzonitrile, butyronitrile, valeronitrile, 1,2-dichloroethane, dimethylformamide, dimethyl sulfoxide, A single solvent such as trimethyl phosphate or triethyl phosphate or a mixed solvent of two or more kinds can be used.

Among the above-mentioned 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 20 or more at about 25 ° C. In the high dielectric constant solvent, it is preferable that the electrolytic solution contains ethylene carbonate, propylene carbonate, and a compound in which hydrogen atoms thereof are replaced by another element such as halogen or an alkyl group. 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 one can be used, and LiClO ₄ , LiAsF ₆ , LiPF ₆ , Li
BF ₄ , LiB (C ₆ H ₅ ) ₄ , LiCl, LiBr, Li
_{CH 3 SO 3 Li, LiCF 3} SO 3, LiN (SO 2 C
_{F 3) 2, LiN (SO} 2 C 2 F 5) 2, LiC (SO 2 C
Examples thereof include lithium salts such as F ₃ ) ₃ and LiN (SO ₃ CF ₃ ) ₂ .

Further, gases such as CO ₂ , N ₂ O, CO, SO _{2 and the} like, polysulfide Sx ^2- , vinylene carbonate,
An additive such as catechol carbonate that forms a good film capable of efficiently charging and discharging lithium ions on the surface of the negative electrode may be present in the electrolytic solution in 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 also be used. It is also possible to use a semi-solid electrolyte by fluidizing the above electrolyte solution with a polymer. In the lithium secondary battery of the present invention, between the positive electrode and the negative electrode,
The electrolyte layer can be provided by 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 as its material, nylon, polyester, cellulose acetate, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, tetrafluoroethylene, polypropylene, polyethylene, polybutene, etc. The polyolefin-based polymer can be mentioned. Further, a non-woven fabric filter of glass fiber or the like, or a composite non-woven fabric filter of glass fiber and polymer fiber can also be used. The chemical and electrochemical stability of the separator is an important factor, and from this point, the material is preferably a polyolefin polymer, and in particular, it is made of polyethylene from the viewpoint of the self-closing 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 shape retention at high temperature, and the lower limit of its molecular weight is preferably 500,000, more preferably 1,000,000, and most preferably 1,500,000.
On the other hand, the upper limit of the molecular weight is preferably 5,000,000, more preferably 4,000,000, and most preferably 3,000,000. This is because if the molecular weight is too large, the fluidity is so low that the pores of the separator may not close when heated.

[0043]

The present invention will be described in more detail with reference to the following examples. In the following, SUS powder (baking) is SUS powder baked at a baking temperature of 900 ° C. for 10 hours. [Measurement of magnetic flux density at which compound is attracted] Sample powder and samarium magnet (surface magnetic flux density of 6000 gauss) are placed on a horizontally spread paper with a distance of about 10 cm, and the magnet is gradually brought close to the sample. The magnetic flux density at the place where the sample was attracted to the magnet was measured with a magnetometer (TM-501) manufactured by Kanetech. The attracted magnetic flux densities of typical compounds are exemplified below.

[0044]

[Table 1]

Example 1 1 g of iron powder having a particle size of about 100 μm with respect to 10 g of MnO _2.
Spread the mixture on the paper with a magnetic flux density of 600
The magnet of 0 gauss was brought close to the sample until the magnetic force received by the sample became 3000 gauss. In this state, the paper was rocked right and left for 5 minutes. As a result, 1 g of iron powder was collected by the magnet.

Example 2 SUS was prepared in the same manner as in Example 1 except that 1 g of SUS powder (unfired) having a particle size of about 100 μm was used instead of iron powder.
1 g of powder (unfired) was collected by a magnet. Example 3 1 g of SUS powder (calcined) was collected by a magnet in the same manner as in Example 1 except that SUS powder (calcined) having a particle size of about 100 μm was used instead of iron powder.

Example 4 10 g of MnO ₂ from which iron powder was removed obtained in Example 1 was heat treated at 900 ° C. for 10 hours to obtain Mn ₂ O ₃ . Next, the Mn ₂ O ₃ , AlOOH, and LiOH.H ₂ O were added to Li: Mn: Al = 1.04: 1.84: 0.
Pure water was added to what was weighed to be 12 (molar ratio) to prepare a slurry having a solid content concentration of 30% by weight. While stirring this slurry, the average particle size of the solid content in the slurry was 0.3 μm using a circulation type medium stirring type wet pulverizer.
Until it becomes, spray dryer equipped with a nozzle having a droplet atomizing mechanism (Micro mist dryer MDP-050 manufactured by Fujisaki Electric Co., nozzle type is circle edge nozzle, drying tower size is 2500 mmφ × 4800
mmH) was used for spray drying.

The amount of dry gas introduced at this time was 23 m ³ / mi.
n, the drying gas inlet temperature was 90 ° C. As the spray nozzle, a type having a diameter of 30 mmφ and capable of horizontal spray in the direction of 360 ° (annular) is used, and the slurry outlet clearance of the nozzle is 600 μm, and the clearance of the pressurized gas outlet for atomizing the slurry is It was set to 350 μm. The slurry feed rate was 560 g / min, and the pressurized gas stream feed rate was 1200 L / min (the gas stream gas linear velocity was 330 m / s). The exhaust gas temperature during spray drying under these conditions was 45 ° C.

The dried granulated particles were calcined at 900 ° C. for 10 hours to obtain a positive electrode active material. As a result, average particle size 9μ
m approximately spherical granulated particles were obtained. When the X-ray diffraction was measured, it was confirmed to have the structure of a cubic spinel-type lithium manganese compound. Comparative Example 1 The procedure of Example 1 was repeated except that the magnet was brought closer until the magnetic force received by the sample reached 50 Gauss, but the iron powder could not be recovered by the magnet.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the magnet was brought closer to the sample until the magnetic force received by the sample reached 4000 Gauss, and MnO ₂ was also adsorbed to the magnet together with the iron powder.

[0051]

EFFECTS OF THE INVENTION According to the present invention, it is possible to prevent iron from being mixed into the battery material, and further to prevent SUS powder from being mixed into the battery material.

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Claims (11)

[Claims] 1. MnO ₂ content of 100 Gauss or more, 320
A method for producing Mn ₂ O ₃ , which comprises firing after passing a magnetic field of less than 0 Gauss. 2. MnO ₂ content of 100 Gauss or more, 320
A method for producing a lithium-manganese composite oxide, which comprises firing Mn ₂ O ₃ after passing a magnetic field of less than 0 Gauss, mixing Mn ₂ O ₃ with a thium compound, and firing the mixture. 3. MnO ₂ of 100 Gauss or more, 320
Firing after passing a magnetic field of less than 0 gauss to obtain Mn ₂ O ₃ , then mixing the Mn ₂ O ₃ with a lithium compound in a solvent to obtain a slurry, spray drying the slurry and then firing A method for producing a lithium manganese composite oxide, comprising: 4. The manufacturing method according to claim 1, wherein the lower limit of the magnetic flux density of the magnetic field is 700 gauss or more. 5. The mixing ratio of the lithium compound and MnO ₂ is such that Li / Mn = 0.4-in terms of Li atom and Mn atom.
The manufacturing method according to claim 2, wherein the amount ratio is 0.6. 6. The production method according to claim 2, wherein a compound containing a metal element other than lithium and manganese is mixed in a solvent in addition to MnO ₂ and the lithium compound. 7. A mixture ratio of a compound containing a metal element (hereinafter referred to as “other metal”) other than lithium and manganese is Mn.
In terms of atoms and other metal atoms, the other metal element is 2.5 to Mn.
The production method according to claim 6, wherein the amount ratio is 30 mol%. 8. A lithium manganese composite oxide is represented by the following formula: Li _b Mn _2-a Me _a O ₄ (Me is B, Al, Sn, Cu, Ti, Zn, Co, N.
represents at least one selected from the group consisting of i, and 0 ≦
The manufacturing method according to claim 2, wherein b ≦ 1.5 and 0 <a ≦ 1). 9. A lithium manganese composite oxide produced by the production method according to claim 2. 10. A lithium secondary battery having a positive electrode, a negative electrode and an electrolyte containing the lithium-manganese composite oxide produced by the production method according to claim 2. 11. MnO ₂ of 100 Gauss or more, 32
M characterized by passing a magnetic field of less than 00 Gauss
Method for removing metal powder from nO ₂ .