JP2001122626A - Lithium-manganese multi-component oxide, method for manufacturing the same, lithium secondary battery positive electrode active material and lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium-manganese multi-component oxide which is enhanced in the capacity maintenance rate of a discharge capacity when used as a positive electrode active material of a lithium secondary battery a sharp grain size distribution and a high flow property. SOLUTION: This lithium-manganese multi-component oxide is expressed by the general formula, LixMn2-yMeyO4-z (where, Me is a metal element or transition metal element of an atomic number 11 or above exclusive of Mn; (x) assumes of a value of 0>x<2.0; (y) 0<=y<0.6 and (z) 0<=z<2.0) and the average grain size thereof is 0.1 to 50 μm, the (n) value by Rosin-Rammler is >=3.5 and the BET specific surface area is 0.1 to 1.5 m2/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithium manganese composite oxide, particularly a lithium composite oxide useful as a positive electrode active material having excellent energy density for lithium secondary batteries.
The present invention relates to a method for manufacturing the same and a lithium secondary battery using the same.

[0002]

2. Description of the Related Art In recent years, portable electronic devices have become more portable.
As cordless technology has rapidly progressed, lithium secondary batteries have begun to be used as power sources for small electronic devices. Regarding this lithium secondary battery, Mizushima et al. Reported in 1980 that lithium cobaltate was useful as a positive electrode active material for lithium secondary batteries ("Material Research Bulletin" vol. 115, 783-789 (19)
Since 1980), research and development on lithium-based composite oxides have been actively promoted, and lithium cobaltate, lithium nickelate, lithium manganate and the like have been known as positive electrode active materials. Among these, lithium manganate has been proposed variously since the raw material is cheaper and the production cost is lower than lithium cobaltate and lithium nickelate.

For example, Japanese Patent Application Laid-Open No. 9-86993 discloses that Mn has an average degree of oxidation of 3.4 to 3.6, a BET specific surface area of 1 m ² / g or more, and substantially all of the primary particles. 1
Lithium manganese oxide having a particle size of less than μm
JP-A-162826 discloses a positive electrode active material in which the average particle size of lithium manganese oxide is 5 μm or more and 30 μm or less, and a particle size distribution width with respect to the average particle size is ± 20% or less, and JP-A-10-172569. Discloses a lithium manganese oxide comprising secondary particles having an average particle diameter of 20 to 100 μm formed by aggregating primary particles having an average particle diameter of 0.01 to 3 μm.

[0004]

However, since the above lithium manganese oxide and the like have a broad particle size distribution and low fluidity, when the above lithium manganese oxide or the like is used as a positive electrode active material, a sheet of a positive electrode is formed. This causes a problem that the coating cannot be performed uniformly. Therefore, in a secondary battery using the lithium manganese oxide or the like as a positive electrode active material, unevenness occurs in the positive electrode, current is locally concentrated on a thin portion, and the like, and as the number of times of charging and discharging increases, There is a problem that the discharge capacity is reduced, that is, the capacity retention rate of the discharge capacity is low.

Accordingly, it is an object of the present invention to provide a sharp particle size distribution and high fluidity. Therefore, when used as a positive electrode active material of a lithium secondary battery, the initial discharge capacity is high and the discharge capacity is high. Provided is a lithium-manganese composite oxide having a high capacity retention ratio, a method for producing the same, a lithium secondary battery positive electrode active material containing the lithium manganese composite oxide, and a lithium secondary battery using the lithium secondary battery positive electrode active material. It is in.

[0006]

Under these circumstances, the present inventors have conducted intensive studies and have found that a manganese compound, a lithium compound and, if necessary, a metal compound or a transition metal compound having an atomic number of 11 or more excluding manganese. Mixing and firing, the following general formula (1): Li _x Mn _2-y Me _y O _4-z (1) (In the formula, Me is a metal element or a transition metal element having an atomic number of 11 or more other than Mn. , X is 0 <x <2.0, y is 0
≦ y <0.6, z takes a value of 0 ≦ z <2.0. In obtaining a lithium manganese composite oxide represented by the above), if the manganese compound, or a metal compound or a transition metal compound having an atomic number of 11 or more excluding the manganese compound and manganese, is heated to a temperature of 900 ° C. or more before firing, Alternatively, if the heat treatment is further performed at a temperature lower than 900 ° C., the obtained lithium manganese composite oxide has a sharp particle size distribution and excellent fluidity, and a lithium secondary battery using the lithium manganese composite oxide as a positive electrode active material is The inventors have found that the initial discharge capacity is high and the capacity retention ratio of the discharge capacity is high, and have completed the present invention. Further, the present inventors have determined that the average particle size and B
It has also been found that the ET specific surface area is within a specific range, and the n-value by Rosin-Rammler is not less than a specific value.

That is, the present invention provides a compound represented by the following general formula (1): Li _x Mn _2-y Me _y O _4-z (1) (where Me is a metal element other than Mn and having a atomic number of 11 or more or a transition metal) X is 0 <x <2.0, y is 0
≦ y <0.6, z takes a value of 0 ≦ z <2.0. ), The average particle size is 0.1 to 50 μm, the n value by Rosin-Rammler is 3.5 or more, and the BET specific surface area is 0.1 to 1.5 m ^2.
/ g is provided.

The present invention also relates to a method of heating a manganese compound (A) to a temperature of 900 ° C. or more to obtain a manganese oxide, and then a lithium compound or a metal compound having an atomic number of 11 or more excluding the lithium compound and manganese. Alternatively, a transition metal compound is mixed and fired, or (B) a manganese compound and a metal compound or a transition metal compound having an atomic number of 11 or more excluding manganese are heated to a temperature of 900 ° C. or more, and then a lithium compound is mixed. Li _x Mn _2-y Me _y O _4-z (1) (wherein Me is a metal element or a transition metal element having an atomic number of 11 or more other than Mn) Yes, x is 0 <x <2.0, y is 0
≦ y <0.6, z takes a value of 0 ≦ z <2.0. The present invention provides a method for producing a lithium manganese composite oxide, characterized by obtaining a lithium manganese composite oxide represented by the formula (1).

Further, according to the present invention, the manganese compound (C) is subjected to a heat treatment at a temperature of 900 ° C. or more, and further a heat treatment at a temperature of less than 900 ° C., and then a lithium compound or an atomic number 11 excluding the lithium compound and manganese is added. The above metal compound or transition metal compound is mixed and fired, or (D) a manganese compound and a metal compound having an atomic number of 11 or more excluding manganese or a transition metal compound are heated to 900 ° C. or more, and further heated to 900 ° C. A method for producing a lithium manganese composite oxide, which comprises subjecting a lithium compound to mixing and calcining after heat treatment at a temperature of less than 100 ° C. to obtain a lithium manganese composite oxide represented by the general formula (1). Is provided.

[0010] The present invention also provides a positive electrode active material for a lithium secondary battery comprising the above-mentioned lithium manganese composite oxide.

Further, the present invention provides a lithium secondary battery characterized by using the above-mentioned positive electrode active material for a lithium secondary battery.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The lithium manganese composite oxide according to the present invention is represented by the above general formula (1) and has a spinel structure. In the above general formula (1), Me is a metal element or a transition metal element having an atomic number of 11 or more other than Mn, such as magnesium, aluminum, titanium, vanadium, chromium, cobalt, iron, copper, zinc, yttrium, and niobium. , Molybdenum and the like. They are,
One type or a combination of two or more types can be used. In the lithium-manganese composite oxide represented by the general formula (1), Me is substituted at a site occupied by Mn as necessary. Among the lithium manganese composite oxides, a lithium manganese composite oxide containing Me, a so-called Me-substituted product, makes the intercalation / deintercalation reaction of lithium ions in a lithium secondary battery smoother and higher. This is preferable because it can be performed at a potential.

The lithium manganese composite oxide has an average particle size of 0.1 to 50 μm, preferably 1 to 20 μm,
More preferably, it is 4 to 20 μm. Also, Rosin
N value by Ramler is 3.5 or more, preferably 4.0 to 4.0
6.0. Here, the n value by Rosin-Rammler is a value calculated by analyzing the formula R = a · exp (−bx ⁿ ) of the rosin-Rammler distribution using a laser particle size distribution analyzer. The higher the value, the sharper the particle size distribution. The lithium manganese composite oxide according to the present invention has a sharp particle size distribution and high fluidity, since the n value determined by Rosin-Rammler is not less than the above value.

The lithium manganese composite oxide according to the present invention has a BET specific surface area of 0.1 to 1.5 m ² / g, preferably 0.1 to ¹ m ² / g, more preferably 0.1 to 0 m ² / g. .
7 m ² / g. When the BET specific surface area is within the above range,
It is preferable because the amount of water adsorbed on the particle surface after the synthesis and before the production of the battery is small. In addition, the lithium manganese composite oxide according to the present invention has an average particle diameter within the above range, the surface of the particles is smooth, and the fluidity is high, so the angle of repose is 60 ° or less, preferably 40 to It is 60 °, more preferably 51-59 °.

Next, a method for producing a lithium manganese composite oxide according to the present invention will be described. In the first method for producing a lithium-manganese composite oxide according to the present invention, (A) a manganese compound is subjected to a heat treatment at a temperature of 900 ° C. or higher to obtain a manganese oxide, and then the lithium compound or the lithium compound and manganese are removed. Mixing and baking a metal compound or a transition metal compound having an atomic number of 11 or more excluding the manganese compound and a heat treatment of a metal compound or a transition metal compound having an atomic number of 11 or more excluding manganese to 900 ° C. or more. Then, a lithium compound is mixed and calcined to obtain a lithium manganese composite oxide represented by the following general formula (1).

The second method for producing a lithium-manganese composite oxide according to the present invention comprises the step of:
After heat treatment at a temperature of 00 ° C. or more, and further heat treatment at a temperature of less than 900 ° C., a lithium compound or a metal compound or a transition metal compound having an atomic number of 11 or more excluding a lithium compound and manganese is mixed and fired. Or (D) heat-treating a manganese compound and a metal compound or a transition metal compound having an atomic number of 11 or more excluding manganese to a temperature of 900 ° C. or more, and further heat-treating at a temperature of less than 900 ° C .; Or calcination to obtain a lithium manganese composite oxide represented by the following general formula (1).

The raw materials include a manganese compound, a lithium compound and, if necessary, an atomic number 11 excluding manganese.
The above metal compounds or transition metal compounds are used. Examples of the metal element or the transition metal element having an atomic number of 11 or more excluding manganese include magnesium, aluminum,
Examples include titanium, vanadium, chromium, cobalt, iron, copper, zinc, yttrium, niobium, and molybdenum.

The manganese compound, lithium compound, and metal compound having an atomic number of 11 or more or a transition metal compound other than manganese may be any industrially available one. Oxides, hydroxides, carbonates, nitrates and organic acid salts. Specifically, as the manganese compound, electrolytic manganese dioxide and chemically synthesized manganese dioxide are preferable because they are industrially easily available and inexpensive. As the lithium compound, lithium carbonate is preferable because it is industrially easily available and inexpensive. Any of these raw materials may have any production history, but is preferably as low as possible in content of impurities in order to produce a high-purity lithium-manganese composite oxide. The manganese compound and the lithium compound can be used alone or in combination of two or more. Further, as the metal compound or transition metal compound having an atomic number of 11 or more excluding manganese, one or a combination of two or more of the above-described compounds of the exemplified metals can be used.

In the first production method of the present invention, the manganese compound or a metal compound or a transition metal compound having an atomic number of 11 or more excluding the manganese compound and manganese is mixed with another compound at a temperature of 900 ° C. or more before firing. Preferably 9
Heat treatment at 40 ° C. or higher, more preferably 1000 to 1200 ° C. for a predetermined time (hereinafter “particle growth heat treatment”)
Also say. ). The heat treatment may be performed at least once before firing, and may be performed twice or more before firing.

In a normal state without heat treatment, for example, as shown in FIG. 1, the manganese compound has a peak due to fine particles having a particle size of about 0.1 to 20 μm and a particle size distribution of less than 1 μm. It is a broad one having a plurality of peaks with the peaks due to the above particles. However, by the heat treatment of the present invention, for example, as shown in FIG. 2 or FIG. 3, fine particles grow and substantially no fine particles of less than 1 μm substantially exist, and the particle diameter increases. Only one peak due to particles having a particle size distribution of about 2 to 100 μm and a particle size distribution of 2 μm or more becomes extremely sharp. The temperature of the above heat treatment is 900
If the temperature is lower than 0 ° C, the particles hardly grow, which is not preferable. On the other hand, if the temperature exceeds 1200 ° C., the manganese compound sinters and it becomes difficult to control the particle size, which is not preferable. The time for the particle growth heat treatment is 0.5 to 24 hours, preferably 1 to 20 hours, and more preferably 5 to 12 hours. When the heat treatment time is 1 hour or more, the growth of the manganese compound particles is substantially saturated, but it is preferable to keep the temperature within the above-mentioned temperature range since the particle surface becomes smooth.

In the second production method of the present invention, the manganese compound or a metal compound or a transition metal compound having an atomic number of 11 or more excluding the manganese compound and manganese is mixed with another compound and heated for particle growth before firing. And
Further, it is subjected to heat treatment at a temperature lower than 900 ° C., preferably 200 to 800 ° C., more preferably 400 to 700 ° C. for a predetermined time (hereinafter, also referred to as “phase change heat treatment”). In this phase transition heat treatment, after the particle growth heat treatment, the phase transition from trimanganese tetroxide having grown the particles to dimanganese trioxide is performed. If the phase transition heat treatment temperature is lower than 200 ° C., it takes a long time for the phase transition from trimanganese tetroxide to dimanganese trioxide, which is not industrially advantageous. On the other hand, if the temperature exceeds 900 ° C., phase transition to dimanganese trioxide tends to be difficult to occur, which is not preferable. The time of the phase transition heat treatment is usually 3 to 24 hours, preferably 5 to 12 hours. The phase transition from trimanganese tetroxide to dimanganese trioxide can be confirmed by X-ray diffraction, and if necessary, heat-treated at the above temperature range as many times as necessary until the peak of trimanganese tetroxide disappears. it can. In addition, when the phase change heat treatment is performed on trimanganese tetroxide having appropriately grown particles, it is preferable to supply sufficient oxygen to the particles by means of grinding or the like after cooling in advance.

By the above-mentioned phase transition heat treatment, dimanganese trioxide has an average particle diameter of 5 to 30 μm, preferably 7 to 15 μm, as measured by a laser particle size distribution analyzer.
And a sharp particle size distribution substantially free of particles of 1 μm or less.

In the production method according to the present invention, for example, the above-mentioned manganese compound, lithium compound and, if necessary, a metal compound or a transition metal compound having an atomic number of 11 or more excluding manganese are mixed. Mixing may be performed by either a dry method or a wet method, but a dry method is preferred because of easy production. In the case of dry mixing, it is preferable to use a blender in which the raw materials are uniformly mixed. In the case of wet mixing, for example, a manganese salt is added to and mixed with a lithium salt aqueous solution, and the mixture is stirred, or a manganese salt and a metal compound having an atomic number of 11 or more excluding manganese or a transition metal compound are added and mixed to a lithium salt aqueous solution. It is preferable to stir. In the case of wet mixing, it is preferable to remove the water after mixing to obtain a dried mixture.

Next, the mixture is fired. The sintering may be performed at a temperature at which a lithium manganese composite oxide can be produced, and the sintering temperature is 500 to 1100 ° C., preferably 700.
９００900 ° C. The firing time is 1 to 24 hours,
Preferably, it is 10 to 20 hours. Firing may be performed in the air or in an oxygen atmosphere, and is not particularly limited.

Further, the firing method will be described with reference to specific examples, but the firing method is not limited thereto. In the following, manganese compounds are represented by A, A ′, A ″,
a ′ or a ″, a lithium compound is also represented by B or B ′, and a metal compound or a transition metal compound having an atomic number of 11 or more excluding manganese is represented by C, C ′ or c ′. The compound, A 'is a manganese compound heat-treated once by grain growth, A "is a manganese compound heat-treated twice by grain growth, and a' is manganese oxide obtained by heat-treating A 'at a temperature of less than 900 ° C. , A ″ is a manganese oxide obtained by subjecting A ″ to a phase transition heat treatment at a temperature of less than 900 ° C., B is a lithium compound that has not been subjected to heat treatment, B ′ is a lithium compound that has been subjected to single grain growth heat treatment, and C is a heating compound A metal compound or transition metal compound having an atomic number of 11 or more excluding manganese that has not been treated, C ′ is a metal compound or a transition metal compound having an atomic number of 11 or more excluding manganese that has been once heat-treated, and c ′ is C ′. 90 Atomic number 11 or more metal compounds excluding phase transition heat treated manganese at temperatures below ℃ or an transition metal compound.

(1) A is heat-treated at 900 ° C. or higher for 0.5 to 24 hours to grow particles into A ′, and then A ′, B and C are mixed and fired at 500 to 1100 ° C. for 1 to 24 hours. how to. Further, in this method, C is mixed with A and then heat-treated to form a mixture of A ′ and C ′, and then B is added to the mixture to form a mixture of A ′, B and C ′, and then the same process is performed. May be fired. (2) After A was subjected to a particle growth heat treatment (first time) in the same manner as in (1) to form A ′, A ′ and unheated A were mixed, and a particle growth heat treatment (A) was performed in the same manner as the first time. Second) to form a mixture of A ″ and A ′, and B and C mixed into this mixture,
A method of preparing a mixture of A ″, A ′, B and C, followed by baking in the same manner as in (1). In this method, C is mixed with A ′ and A during the second particle growth heat treatment. A ′, A and C, which were subjected to a particle growth heat treatment (second time) to form a mixture of A ″, A ′, and C ′, and further B was added to A ′, A ′, B, and C After forming the mixture of ′, baking may be performed similarly.

(3) After A is heated to 900 ° C. or higher for 0.5 to 24 hours to form A ′, A ′ is further added for 200 hours.
After a phase transition heat treatment at a temperature lower than 〜900 ° C. for 3 to 24 hours to obtain a ′, a ′ and B are mixed, and 500 to 110
A method of baking at 0 ° C. for 1 to 24 hours. In this method, after C is mixed with A and then subjected to a particle growth heat treatment to form a mixture of A ′ and C ′, and further subjected to a particle growth heat treatment at a temperature of less than 200 to 900 ° C. to obtain a ′ and c ', A mixture of B' was added to the mixture to obtain a ', B and c'.
And may be similarly baked. (4) After A is subjected to the particle growth heat treatment (first time) in the same manner as in (3) to A ′, the A ′ and the untreated A are mixed, and the particle growth heat treatment (A) is performed in the same manner as the first time (A). Second) to form a mixture of A ′ and A ″, and subject this mixture to a phase transition heat treatment at a temperature lower than 200 to 900 ° C. for 3 to 24 hours to form a mixture of a ′ and a ″, and adding B and C to this mixture. Mix, a ',
a ", a method of baking in the same manner as after forming a mixture of B and C. In this method, C is mixed with A and A 'to form A, A' and C before the second heat treatment, This was subjected to a particle growth heat treatment (second time) to obtain a mixture of A ′, A ″ and C ′.
A ′, a ″
And c ′, and further B is added to a ′,
After forming a mixture of a ″, B and c ′, baking may be performed in the same manner.

In the above methods (2) and (4), untreated A having a small particle size is added to A ′ having a large particle size by heating once, and mixed. The mixture of 'and A has a particle size between A' and A. For this reason,
It is preferable that the particle diameter of the lithium manganese composite oxide to be fired can be adjusted by changing the mixing ratio of A ′ and A.

In the present invention, in the method for producing a lithium manganese composite oxide according to the above-mentioned methods (1) to (4),
Atomic number 11 excluding manganese compound and manganese before firing
The mixture with the above metal compound or transition metal compound is mixed with 90
Heat treatment at a temperature of 0 ° C. or more, or heat treatment at a temperature of 900 ° C. or more, further heat treatment at a temperature of less than 900 ° C.,
It is preferable to perform calcination by adding a lithium compound, because in the formula of the lithium manganese composite oxide represented by the general formula (1), Mn and Me are uniformly substituted.

In the above methods (1) to (4), once the lithium manganese composite oxide is fired, B is further added to and mixed with the lithium manganese composite oxide to reduce the lithium composition ratio. After the composition ratio of lithium in the general formula (1) is made to be more than the composition ratio x, the mixture may be fired again to obtain a lithium manganese composite oxide. When the obtained lithium manganese composite oxide is used as a positive electrode active material of a lithium secondary battery, the initial discharge capacity and the capacity retention rate of the discharge capacity of the lithium secondary battery are increased. In particular, when a lithium manganese composite oxide obtained by a method including the above-described phase transition heat treatment method is used as a positive electrode active material of a lithium secondary battery, the capacity retention ratio (cycle characteristics) of the discharge capacity at a high temperature such as 50 ° C. is reduced. Get higher.

After firing, the mixture is appropriately cooled and pulverized as necessary to obtain a lithium manganese composite oxide. The pulverization performed as necessary is appropriately performed, for example, when the lithium-manganese composite oxide obtained by firing is in the form of a brittlely bonded block, but the lithium-manganese composite oxide particles themselves have the above specific average. Particle size, rosin-Rammler n value,
It has a BET specific surface area. The obtained lithium manganese composite oxide has an average particle diameter of 0.1 to 50 μm.
, Preferably 1 to 20 μm, more preferably 4 to
20 μm and an n value of 3.5 according to Rosin-Rammler.
Above, preferably 4.0 to 6.0, the BET specific surface area is 0.1 to 1.5 m ² / g, preferably 0.1 to ¹ m ² / g,
More preferably, it is 0.3 to 0.7 m ² / g. The angle of repose is 60 ° or less, preferably 40 to 60 °, and more preferably 51 to 59 °. The lithium manganese composite oxide of the present invention can be used as a positive electrode active material for a lithium secondary battery.

The lithium manganese composite oxide is used as the positive electrode active material for a lithium secondary battery according to the present invention. The positive electrode active material is one raw material of a positive electrode mixture for a lithium secondary battery described later, that is, a mixture of a positive electrode active material, a conductive agent, a binder, and, if necessary, a filler. Since the positive electrode active material for a lithium secondary battery according to the present invention is composed of the above-described lithium manganese composite oxide, kneading is easy when mixing with other raw materials to prepare a positive electrode mixture, and the obtained positive electrode The coatability when applying the mixture to the positive electrode current collector is facilitated.

The lithium secondary battery according to the present invention uses the above-mentioned positive electrode active material for a lithium secondary battery.
It consists of a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt. The positive electrode is formed, for example, by coating and drying a positive electrode mixture on a positive electrode current collector, and the positive electrode mixture includes a positive electrode active material, a conductive agent, a binder, and a filler added as necessary. Consists of In the lithium secondary battery according to the present invention, since the particle size distribution of the positive electrode active material of the lithium secondary battery is sharp, the lithium manganese composite oxide as the positive electrode active material is uniformly applied to the positive electrode. Therefore, the current does not locally concentrate on the positive electrode, and the capacity retention rate of the discharge capacity is high.

The positive electrode current collector is not particularly limited as long as it is an electron conductor which does not cause a chemical change in the constructed battery. Examples thereof include stainless steel, nickel, aluminum, titanium, calcined carbon, aluminum, and the like. Examples thereof include those obtained by surface-treating carbon, nickel, titanium, and silver on the surface of stainless steel.

Examples of the conductive agent include conductive materials such as graphite such as natural graphite and artificial graphite, carbon black, acetylene black, carbon fiber, metal and nickel powder. Examples of the natural graphite include scale-like graphite , Flaky graphite and earthy graphite. These are one or two
It can be used in combination of more than one kind. The mixing ratio of the conductive agent is 1 to 50% by weight, preferably 2 to 50% by weight in the positive electrode mixture.
30% by weight.

As the binder, for example, polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, regenerated cellulose, diacetylcellulose, polyvinylpyrrolidone, ethylene-propylene-diene terpolymer (EPD)
M), sulfonated EPDM, styrene butadiene rubber,
Examples thereof include polysaccharides such as fluorine rubber and polyethylene oxide, thermoplastic resins, and polymers having rubber elasticity. These can be used alone or in combination of two or more. The mixing ratio of the binder is 2 to 30% by weight, preferably 5 to 15% by weight in the positive electrode mixture.

The filler suppresses the volume expansion of the positive electrode in the positive electrode mixture, and is added as necessary. As the filler, any fibrous material that does not cause a chemical change in the configured battery can be used. For example, olefin-based polymers such as polypropylene and polyethylene, fibers such as glass and carbon are used.
The amount of the filler added is not particularly limited, but in the positive electrode mixture,
0-30% by weight is preferred.

The negative electrode is formed by coating and drying the negative electrode material on the negative electrode current collector. The negative electrode current collector is not particularly limited as long as it is an electronic conductor that does not cause a chemical change in the configured battery, for example, stainless steel,
Examples thereof include nickel, copper, titanium, aluminum, calcined carbon, copper and stainless steel having a surface treated with carbon, nickel, titanium, and silver, and an aluminum-cadmium alloy.

The negative electrode material is not particularly restricted but includes, for example, carbonaceous materials, metal composite oxides, lithium metals, lithium alloys and the like. Examples of the carbonaceous material include a non-graphitizable carbon material and a graphite-based carbon material. Examples of the metal composite oxide include Sn
_p M ¹¹ _-p M ² _{q Or} (where M ¹ represents one or more elements selected from Mn, Fe, Pb and Ge, and M ² represents A
l, B, P, Si, at least one element selected from the first, second, and third groups of the periodic table and a halogen element;
<P ≦ 1, 1 ≦ q ≦ 3, and 1 ≦ r ≦ 8. And the like.

As the separator, an insulating thin film having a high ion permeability and a predetermined mechanical strength is used. Sheets and nonwoven fabrics made of olefin polymers such as polypropylene, glass fiber, polyethylene, or the like are used because of their organic solvent resistance and hydrophobicity. The pore diameter of the separator may be any range generally useful for batteries, for example, 0.01 to 10
μm. The thickness of the separator may be within the range for general batteries, and is, for example, 5 to 300 μm.
When a solid electrolyte such as a polymer is used as an electrolyte to be described later, the solid electrolyte may also serve as a separator. In addition, pyridine, triethyl phosphite,
A compound such as triethanolamine may be added to the electrolyte.

The non-aqueous electrolyte containing a lithium salt is composed of a non-aqueous electrolyte and a lithium salt. As the non-aqueous electrolyte, a non-aqueous electrolyte or an organic solid electrolyte is used. Examples of the non-aqueous electrolyte include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,
2-dimethoxyethane, tetrahydroxyfuran, 2-
Methyl tetrahydrofuran, dimethyl sulfoxide,
1,3-dioxolan, formamide, dimethylformamide, dioxolan, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolan derivative, sulfolane,
Solvents in which one or more aprotic organic solvents such as 3-methyl-2-oxazodinone, a propylene carbonate derivative, a tetrahydrofuran derivative, diethyl ether, and 1,3-propanesulfone are mixed.

As the organic solid electrolyte, for example, polyether
Tylene derivative or polymer containing it, polypropylene
Oxide derivative or polymer containing the same, phosphate phosphate
Terpolymers and the like. As the lithium salt,
What is dissolved in the non-aqueous electrolyte is used, for example, Li
ClO_Four, LiBF_Four, LiPF₆, LiCF_ThreeS
O _Three, LiCF_ThreeCO_Two, LiAsF₆, LiSb
F₆, LiB_TenCl_Ten, LiAlCl_Four, Chloroborane
Lithium, lithium lower aliphatic carboxylate, tetraphenyl
One or a mixture of two or more salts such as lithium borate
No.

The shape of the battery can be applied to any of buttons, sheets, cylinders, corners and the like. Although the use of the lithium secondary battery according to the present invention is not particularly limited, for example, electronic devices such as notebook computers, laptop computers, pocket word processors, mobile phones, cordless handsets, portable CD players, radios, automobiles, and electric vehicles And consumer electronic devices such as game devices.

[0044]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but this is merely an example and does not limit the present invention.

(Production of lithium manganese composite oxide) Example 1 20 g of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm was heated at 1000 ° C. for 12 hours, cooled, and lightly pulverized. The average particle size and the particle size distribution before the heat treatment are shown in Table 1 and FIG. 1, and the average particle size and the particle size distribution after the heat treatment are shown in Table 1 and FIG. Next, 4.48 g of lithium carbonate having an average particle size of 3.0 μm was added to the heat-treated electrolytically synthesized manganese dioxide, and the mixture was placed in an alumina crucible and fired at 900 ° C. for 12 hours in an air atmosphere. The obtained compound is a LiM having a spinel structure by X-ray diffraction.
It was confirmed to be n ₂ O ₄ . Table 2 shows the average particle size, rosin-Rammler n value, BET specific surface area and angle of repose of this compound.

[0046]

[Table 1]

From the results shown in Table 1, FIGS. 1 and 2, by subjecting the raw material manganese compound to a heat treatment at a temperature of 900 ° C. or more, manganese oxide particles grow and extremely sharp particles having no particles of 1 μm or less exist. It turns out that what has a particle size distribution is obtained.

Example 2 An electrolytically synthesized manganese dioxide having an average particle size and a particle size distribution before heat treatment of 3.2 μm as shown in Table 1 and FIG. 1 was used.
Heated for 2 hours, cooled and crushed lightly. The average particle size and the particle size distribution after the heat treatment are shown in Table 1 and FIG.
Next, LiMn ₂ O ₄ having a spinel structure was obtained by X-ray diffraction in the same manner as in Example 1 except that the electrolytically synthesized manganese dioxide heat-treated at 900 ° C. was used. Table 2 shows the average particle size, rosin-Rammler n value, BET specific surface area and angle of repose of this compound.

Example 3 10 g of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm was heated at 1000 ° C. for 12 hours and cooled. Then
To the heat-treated electrolytically synthesized manganese dioxide, 10 g of unheated electrolytically synthesized manganese dioxide was added and mixed, put into an alumina crucible, heated again at 1000 ° C. for 12 hours in an air atmosphere, cooled, and the average particle diameter was reduced. 11.8μ
m was obtained. Next, 4.48 g of lithium carbonate having an average particle size of 3.0 μm was added to the heat-treated product, mixed, placed in an alumina crucible, and fired at 900 ° C. for 12 hours in an air atmosphere. The obtained compound was confirmed by X-ray diffraction to be LiMn ₂ O ₄ having a spinel structure. Average particle size of this compound, Rosin-Rammler n value, BET
Table 2 shows the specific surface area and the angle of repose.

EXAMPLE 4 0.9 g of cobalt oxide having an average particle size of 2.8 μm was added to 20 g of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm, mixed, heated at 1000 ° C. for 12 hours, and cooled. Then, 4.70 g of lithium carbonate having an average particle size of 3.0 μm was added to the heat-treated product, mixed and placed in an alumina crucible.
Calcination was performed at 0 ° C. for 12 hours in an air atmosphere. The obtained compound was LiMn ₂ O ₄ having a spinel structure by X-ray diffraction.
, And no peaks of other cobalt compounds including cobalt oxide (such as lithium cobalt oxide). This confirmed that the compound was a lithium manganese composite oxide in which Co was dissolved. Average particle size of this compound, rosin-Rammler n value,
Table 2 shows the BET specific surface area and the angle of repose.

Example 5 Electrosynthetic manganese dioxide having an average particle size of 3.2 μm 20.0
g and aluminum hydroxide 1.11 having an average particle size of 1.0 μm
g were mixed, heated at 1000 ° C. for 12 hours, and cooled. 4.48 g of lithium carbonate having an average particle size of 3.0 μm was added to the heat-treated product, mixed and placed in an alumina crucible.
It was baked at 0 ° C. for 12 hours in an air atmosphere and cooled. The obtained compound is a LiM having a spinel structure by X-ray diffraction.
It was confirmed to be n ₂ O ₄ . Table 2 shows the average particle size, rosin-Rammler n value, BET specific surface area and angle of repose of this compound.

Example 6 Electrosynthesized manganese dioxide having an average particle size of 3.2 μm 10.0
g and aluminum hydroxide 0.55 having an average particle size of 1.0 μm
g were mixed, heated at 1000 ° C. for 12 hours, and cooled. Next, the heat-treated product, 10.0 g of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm, and 0.55 g of aluminum hydroxide having an average particle size of 1.0 μm were mixed, heated at 1000 ° C. for 12 hours, and cooled. . 4.48 g of lithium carbonate having an average particle size of 3.0 μm was added to the heat-treated electrolytically synthesized manganese dioxide, and the mixture was placed in an alumina crucible.
It was baked at 0 ° C. for 12 hours in an air atmosphere and cooled. The obtained compound is a LiM having a spinel structure by X-ray diffraction.
It was confirmed to be n ₂ O ₄ . Table 2 shows the average particle size, rosin-Rammler n value, BET specific surface area and angle of repose of this compound.

Example 7 Electrosynthetic manganese dioxide having an average particle size of 3.2 μm 20.0
g was heated at 1000 ° C. for 12 hours and cooled. Next, the heat-treated product was heat-treated at 650 ° C. for 8 hours and cooled (average particle size: 9.0 μm). Next, 4.48 g of lithium carbonate having an average particle size of 3.0 μm was added to the heat-treated product, mixed, placed in an alumina crucible, fired at 900 ° C. for 12 hours in an air atmosphere, and cooled. The resulting compound is X
Line diffraction confirmed that the material was LiMn ₂ O ₄ having a spinel structure. Table 2 shows the average particle size, rosin-Rammler n value, BET specific surface area and angle of repose of this compound.

Example 8 10 g of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm was heated at 1000 ° C. for 12 hours and cooled. Then
To the heat-treated electrolytically synthesized manganese dioxide, add and mix 10 g of unheated electrolytically synthesized manganese dioxide,
The mixture was placed in an alumina crucible, heated again at 1000 ° C. for 12 hours in an air atmosphere, and cooled. Next, the heat-treated electrolytically synthesized manganese dioxide was placed in an alumina crucible,
Heat treatment was performed again at 650 ° C. for 8 hours in an air atmosphere, followed by cooling (average particle size: 16.6 μm). Next, 4.48 g of lithium carbonate having an average particle size of 3.0 μm was added to the heat-treated product, mixed, placed in an alumina crucible, and fired at 900 ° C. for 12 hours in an air atmosphere. The obtained compound was confirmed by X-ray diffraction to be LiMn ₂ O ₄ having a spinel structure. Table 2 shows the average particle size, rosin-Rammler n value, BET specific surface area, and angle of repose of this compound.

Example 9 0.9 g of cobalt oxide having an average particle size of 2.8 μm was added to 20 g of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm, mixed, heated at 1000 ° C. for 12 hours, and cooled. Next, the heat-treated mixture of electrolytically synthesized manganese dioxide and cobalt oxide was heat-treated at 650 ° C. for 8 hours and cooled. Next, 4.70 g of lithium carbonate having an average particle size of 3.0 μm was added to the heat-treated product, mixed, placed in an alumina crucible, and fired at 900 ° C. for 12 hours in an air atmosphere. The obtained compound is a LiM having a spinel structure by X-ray diffraction.
It was confirmed that it had a peak of n ₂ O _{4 and} no peak of another cobalt compound containing cobalt oxide (such as lithium cobalt oxide). Thus, the compound becomes C
It was confirmed that o was a solid solution lithium manganese composite oxide. Table 2 shows the average particle size, rosin-Rammler n value, BET specific surface area and angle of repose of this compound.

Example 10 20.0 of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm
g and aluminum hydroxide 1.11 having an average particle size of 1.0 μm
g were mixed, heated at 1000 ° C. for 12 hours, and cooled. Next, the heat-treated product was heat-treated at 650 ° C. for 8 hours and cooled (average particle size: 9.0 μm). Next, 4.48 lithium carbonate having an average particle size of 3.0 μm was added to the heat-treated product.
g, add and mix the mixture into an alumina crucible.
It was fired in an air atmosphere for 2 hours and cooled. The obtained compound was LiMn ₂ O ₄ having a spinel structure by X-ray diffraction.
Was confirmed. Table 2 shows the average particle size, rosin-Rammler n value, BET specific surface area and angle of repose of this compound.

Example 11 Electrosynthetic manganese dioxide having an average particle size of 3.2 μm 10.0
g and aluminum hydroxide 0.55 having an average particle size of 1.0 μm
g were mixed, heated at 1000 ° C. for 12 hours, and cooled. Next, the heat-treated product, 10.0 g of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm, and 0.55 g of aluminum hydroxide having an average particle size of 1.0 μm were mixed, heated at 1000 ° C. for 12 hours, and cooled. . Next, the heat-treated product was heat-treated at 650 ° C. for 8 hours and cooled. Next, the heat-treated product was provided with lithium carbonate 4.4 having an average particle size of 3.0 μm.
8 g was added and mixed, put into an alumina crucible, fired at 900 ° C. for 12 hours in an air atmosphere, and cooled. The obtained compound is LiMn ₂ O having a spinel structure by X-ray diffraction.
It was confirmed to be ₄ . Average particle size of this compound,
Table 2 shows the rosin-Rammler n value, BET specific surface area and angle of repose.

Example 12 Electrosynthetic manganese dioxide having an average particle size of 3.2 μm 20.0
g was heated at 1000 ° C. for 12 hours and cooled. Next, the heat-treated product was heat-treated at 650 ° C. for 8 hours and cooled (average particle size: 9.0 μm). 4.48 g of lithium carbonate having an average particle diameter of 3.0 μm and an average particle diameter of 1.
1.11 g of 0 μm aluminum hydroxide was mixed, put into an alumina crucible, fired at 900 ° C. for 12 hours in an air atmosphere, and cooled. The obtained compound was confirmed by X-ray diffraction to be LiMn ₂ O ₄ having a spinel structure. Average particle size of this compound, rosin-Rammler n value,
Table 2 shows the BET specific surface area and the angle of repose.

COMPARATIVE EXAMPLE 1 20 g of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm and 4.48 g of lithium carbonate having an average particle size of 3.0 μm were added and mixed and placed in an alumina crucible at 900 ° C. for 12 hours under an air atmosphere. Fired. The obtained compound was confirmed by X-ray diffraction to be LiMn ₂ O ₄ having a spinel structure. Average particle size of this compound, Rosin-Rammler n
Table 2 shows the values, the BET specific surface area, and the angle of repose.

Comparative Example 2 20 g of electrolytically synthesized manganese dioxide having an average particle size of 3.2 μm, 1.11 g of aluminum hydroxide having an average particle size of 1.0 μm, and 4.48 g of lithium carbonate having an average particle size of 3.0 μm were added and mixed. It was placed in an alumina crucible and fired at 900 ° C. for 12 hours in an air atmosphere. The obtained compound was confirmed by X-ray diffraction to be LiMn ₂ O ₄ having a spinel structure. Average particle size of this compound, Rosin-Rammler n
Table 2 shows the values, the BET specific surface area, and the angle of repose.

[0061]

[Table 2]

Example 13 (Preparation of lithium secondary battery) 70% by weight of the lithium-manganese composite oxide obtained in Example 1, 20% by weight of graphite powder and 10% by weight of polyvinylidene fluoride were mixed to form a positive electrode mixture. This was dispersed in N-methyl-2-pyrrolidinone to prepare a kneaded paste. The kneaded paste was applied to an aluminum foil, dried, pressed, and punched into a disk having a diameter of 15 mm to obtain a positive electrode plate. Using this positive electrode plate, a lithium secondary battery was produced using square members such as a separator, a negative electrode, a current collector, a mounting bracket, an external terminal, and an electrolyte. As the negative electrode, a metal lithium foil was used, and as the electrolyte, 1 mol of LiPF ₆ was dissolved in 1 liter of a 1: 1 mixture of ethylene carbonate and diethyl carbonate. The obtained lithium secondary battery was operated at 25 ° C., and the discharge capacity was measured. The discharge capacity was measured as follows, and the discharge capacity at the first cycle was the initial discharge capacity, and the retention rate of the discharge capacity when the cycle was repeated 20 times was measured as the capacity retention rate. Table 3 shows the results of the initial discharge capacity and the capacity retention at room temperature or 50 ° C.

Example 14 (Preparation of lithium secondary battery) Instead of 70% by weight of the lithium-manganese composite oxide obtained in Example 1, Example 9 was used.
A lithium secondary battery was produced in the same manner as in Example 13, except that 70% by weight of the lithium-manganese composite oxide obtained in the above was used. The initial discharge capacity and the capacity retention of the obtained lithium secondary battery at room temperature or 50 ° C. were measured in the same manner as in Example 13. Table 3 shows these results.

Comparative Example 3 The procedure of Example 13 was repeated except that 70% by weight of the lithium-manganese composite oxide obtained in Comparative Example 1 was used instead of 70% by weight of the lithium-manganese composite oxide obtained in Example 1. Similarly, a lithium secondary battery was manufactured. The initial discharge capacity and the capacity retention of the obtained lithium secondary battery were measured in the same manner as in Example 13. Table 3 shows the results.

(Evaluation Method for Lithium Secondary Battery) Measurement of Discharge Capacity The positive electrode was charged to 4.3 V at 0.2 mA / cm ² at room temperature, and then discharged to 3.5 V in one cycle. The cycle was performed, and the discharge capacity was measured. On the other hand, under the condition of 50 ° C., the positive electrode was charged to 4.3 V at 0.5 mA / cm ² , and then charged and discharged to 3.5 V for one cycle.
The discharge capacity was measured. -Measurement of capacity retention rate The charge / discharge in the measurement of the discharge capacity was performed for 20 cycles, and the capacity retention rate was calculated by the following equation. Capacity maintenance rate (%) = (discharge capacity at 20th cycle) × 1
00 / (first cycle discharge capacity)

[0066]

[Table 3]

[0067]

The lithium manganese composite oxide of the present invention has a sharp particle size distribution and excellent fluidity. A lithium secondary battery using the lithium manganese composite oxide as a positive electrode active material has a high initial discharge capacity, In addition, the capacity retention ratio of the discharge capacity is high. Further, according to the method for producing a lithium manganese composite oxide of the present invention, a lithium manganese composite oxide having the above-described excellent characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing the particle size distribution of electrolytically synthesized manganese dioxide before heat treatment.

FIG. 2 is a graph showing the particle size distribution of electrolytically synthesized manganese dioxide after heat treatment at 1000 ° C.

FIG. 3 is a graph showing the particle size distribution of electrolytically synthesized manganese dioxide after heat treatment at 900 ° C.

Continued on the front page F term (reference) 4G048 AA04 AB05 AC06 AD04 AD06 AE05 5H029 AJ03 AJ05 AK03 AL06 AL12 AM03 AM04 AM05 AM07 DJ17 HJ02 HJ05 HJ07 HJ13 HJ14 5H050 AA07 AA08 BA17 CA09 CB07 CB11 EA23 HA02 GA05

Claims (8)

[Claims] 1. The following general formula (1): Li _x Mn _2-y Me _y O _4-z (1) (wherein Me is a metal element or a transition metal element having an atomic number of 11 or more other than Mn, x is 0 <x <2.0, y is 0
≦ y <0.6, z takes a value of 0 ≦ z <2.0. ), The average particle size is 0.1 to 50 μm, the n value by Rosin-Rammler is 3.5 or more, and the BET specific surface area is 0.1 to 1.5 m ^2.
/ g lithium manganese composite oxide. 2. The lithium manganese composite oxide according to claim 1, wherein the angle of repose is 60 ° or less. 3. A heat treatment of a manganese compound at a temperature of 900 ° C. or more to obtain a manganese oxide, and then a lithium compound or a metal compound or a transition metal compound having an atomic number of 11 or more excluding the lithium compound and manganese. Or (B) a manganese compound and a metal compound or a transition metal compound having an atomic number of 11 or more excluding manganese are heated to a temperature of 900 ° C. or more, and then a lithium compound is mixed and fired. Li _x Mn _2-y Me _y O _4-z (1) (wherein Me is a metal element other than Mn and has a number of 11 or more or a transition metal element, and x is 0 <x <2.0, y is 0
≦ y <0.6, z takes a value of 0 ≦ z <2.0. A method for producing a lithium manganese composite oxide, comprising obtaining the lithium manganese composite oxide represented by the formula (1). 4. A heat treatment of (C) a manganese compound at a temperature of 900 ° C. or more, and further a heat treatment at a temperature of less than 900 ° C., and then a lithium compound or a metal compound having an atomic number of 11 or more excluding the lithium compound and manganese. Alternatively, a transition metal compound is mixed and calcined, or (D) a manganese compound and a metal compound or a transition metal compound having an atomic number of 11 or more excluding manganese are heat-treated to a temperature of 900 ° C. or more, and then a temperature of less than 900 ° C. after in the heat treatment, mixing the lithium compound, the following formula was either baked _{(1); Li x Mn 2} -y Me y O 4-z (1) ( wherein, Me represents atomic number than Mn 11 or more metal elements or transition metal elements, x is 0 <x <2.0, y is 0
≦ y <0.6, z takes a value of 0 ≦ z <2.0. A method for producing a lithium manganese composite oxide, comprising obtaining the lithium manganese composite oxide represented by the formula (1). 5. The manganese oxide heat-treated to a temperature of 900 ° C. or more is trimanganese tetroxide,
The method for producing a lithium-manganese composite oxide according to claim 4, wherein the manganese oxide heat-treated to a temperature lower than 00 ° C is dimanganese trioxide. 6. The method for producing a lithium manganese composite oxide according to claim 5, wherein said dimanganese trioxide has an average particle diameter in a range of 5 to 30 μm. 7. A positive electrode active material for a lithium secondary battery, comprising the lithium manganese composite oxide according to claim 1 or 2. 8. A lithium secondary battery using the lithium secondary battery positive electrode active material according to claim 7.