JP2001328818A - Powder of laminar lithium-cobalt-manganese oxide, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide powders of a laminar lithium-manganese-cobalt oxide enabling repeated charge and discharge at a high voltage, and especially useful as an active material for a positive electrode of a lithium battery. SOLUTION: The powders of the laminar lithium-cobalt-manganese oxide are characterized by comprising solid solution of a laminar lithium-manganese oxide with a laminar lithium-cobalt oxide and the molar ratio of the cobalt to the manganese to be (45-55):(55-45).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to layered lithium cobalt manganese oxide particles, that is, a solid solution of layered lithium manganese oxide and layered lithium cobalt oxide and a method for producing the same. The present invention relates to a lithium manganese cobalt layered oxide particle powder which can be repeatedly charged and discharged at room temperature, particularly useful as a positive electrode active material of a lithium battery, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, with the development of portable personal computers and mobile phones, demand for batteries as power sources has been increasing. Lithium batteries, in particular, have a low atomic weight and a high ionization energy, and can be expected to have a high electromotive force and a high energy density. ing.

As a positive electrode active material used for a lithium battery, there is a layered oxide such as lithium cobalt oxide and lithium nickel oxide which can generate a voltage of about 4V. In these layered oxides, expensive transition metals such as cobalt and nickel are the main constituent components, and therefore, a layered oxide in which these are replaced with inexpensive iron, manganese, etc. is desired. Has been studied.

[0004] Further, in a lithium battery cathode material,
During charge and discharge, lithium ions are electrochemically inserted into and desorbed from ion sites in the crystal lattice. In a positive electrode material of a secondary battery that is repeatedly charged and discharged, lithium ions are inserted into and desorbed from ion sites in the crystal lattice by electrochemically repeating the insertion and desorption. The diffusion path of lithium ions in the site or crystal lattice is easily lost, and as a result, the reversibility of charge and discharge is reduced. That is, with repeated charge / discharge, battery characteristics are degraded. Therefore, the positive electrode active material is required to be a particle powder having high crystal structure stability.

[0005]

In general, oxide AMO
₂ (M is a transition metal) has a superlattice structure based on the rock salt type, especially layered LiCoO ₂ or LiNi which is called α-NaFeO ₂ type.
O _{2 and the} like have a two-dimensional lithium ion diffusion path.
In oxide AMO _2, 2 for the type of cation present in the structure, the crystal structure appear differently depending on how the sequence of a lithium ion and a transition metal ion. When the A ion is sodium having a large ionic radius, most compounds have a layered α-NaFeO ₂ structure.

However, when the A ion is lithium ion, it is difficult to obtain a layered α-NaFeO ₂ structure by a usual solid-phase method when the radius of the transition metal ion is small, and a spinel structure oxide is easily formed. Therefore, when trying to obtain a layered oxide containing such a transition metal as a component, α-NaF
An ion exchange method between eO ₂ and a lithium compound is used.
However, the layered oxide obtained, taking the alpha-NaFeO ₂ type or tetragonal gamma-LiFeO ₂ type symmetry by the radius of the transition metal ions, the boundary is present in the vicinity of manganese and iron.
This indicates that the layer structure is unstable when manganese or iron ions are included in the components. Further, it indicates that it is difficult to obtain a favorable charge / discharge cycle with an oxide having a layered crystal structure containing manganese or iron as a main constituent component.

On the other hand, there is also a demand for a battery that generates a higher electromotive force than the currently mainstream 4V-class battery.
As a positive electrode active material for high voltage capable of generating a high voltage of about 5.0 V, a part of trivalent manganese of lithium manganese oxide spinel was replaced with transition metals such as Ni, Co, Cr, and Fe. Materials and materials having an olivine structure typified by LiCoPO ₄ have been actively studied, and these composite oxide spinel and olivic acid are used as raw material powders containing cobalt, nickel, chromium, iron, and manganese. It is synthesized by a solid phase method of mixing with a lithium compound powder, and this synthesis requires long-term high-temperature sintering. However,
In such a solid phase method, since the reactivity between the raw material powders at the time of the solid phase reaction is low, it is necessary to perform calcination at a high temperature for a long time, and industrial production is difficult.

Further, in the case of the particle powder obtained by the solid-phase method, it is difficult to say that the distribution of metal ions in the particle powder is uniform, so that it is difficult to obtain a composition having a wide solid solution region. However, there is a problem that sufficient high voltage characteristics cannot be obtained. Therefore, a positive electrode active material particle powder in which the distribution of metal ions in the particle powder is uniform and sufficient high-voltage characteristics can be obtained, and a method of synthesizing such a particle powder at a low temperature in a relatively short time. There is a strong demand.

The present invention has been made in view of the above circumstances, and has a uniform composition.
In particular, lithium cobalt manganese layered oxide particles that operate stably as a high-voltage positive electrode active material for lithium batteries,
It is an object of the present invention to provide a method for manufacturing at a low temperature in a short time.

[0010]

That is, the first aspect of the present invention is as follows.
Contains layered lithium cobalt manganese oxide particles powder comprising a solid solution of layered lithium manganese oxide and layered lithium cobalt oxide, wherein the molar ratio of cobalt to manganese is 45 to 55/55 to 45. I do.

A preferred embodiment is a layered lithium cobalt manganese oxide particle powder having a uniform metal ion distribution.

A preferred embodiment is a layered lithium cobalt manganese oxide used for a high voltage positive electrode active material of a lithium battery.

A second aspect of the present invention is that a manganese salt, a cobalt salt, and a sodium salt are used when the molar ratio of manganese to cobalt is 45 to 50.
55: 55-45, an aqueous solution containing sodium in an equimolar amount to the total amount thereof was evaporated to dryness, and the obtained solid was calcined at 700 to 900 ° C. in an oxygen-containing gas. A method for producing layered lithium-cobalt-manganese-oxide particles is characterized in that the obtained fired particles are mixed with a lithium compound in a solid phase or an organic solvent and ion-exchanged at 140 to 400 ° C.

In a preferred embodiment, prior to firing, the solid particle powder is compression molded into a compact having a compaction density of 2 to 3.5 g / ml.

A third aspect of the present invention is to mix an aqueous solution containing a manganese salt and a cobalt salt such that the molar ratio of manganese to cobalt is 45 to 55:55 to 45 and an oxalic acid aqueous solution having an equivalent amount or more. A precipitate is formed, and the obtained precipitate is filtered, washed, and dried. Then, the dried powder is pyrolyzed at 350 to 500 ° C. in the air, and the obtained particle powder and sodium compound are separated into particles. The total of manganese and cobalt in the powder and sodium are mixed so as to be equimolar, and the mixed powder is fired in an oxygen-containing gas at 700 to 900 ° C., and the obtained fired product particle powder is solidified. The present invention relates to a method for producing layered lithium cobalt manganese oxide particles, which is mixed with a lithium compound in a phase or an organic solvent and ion-exchanged at 140 to 400 ° C.

In a preferred embodiment, prior to firing, the mixed powder is compression-molded into a compact having a compaction density of 2 to 3.5 g / ml.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The layered lithium cobalt manganese oxide particles of the present invention comprise a solid solution of layered lithium manganese oxide and layered lithium cobalt oxide, and the molar ratio of cobalt to manganese is 45 to 55:55 to 45. It is characterized by being. If the molar ratio of cobalt to manganese is other than the above, the charge / discharge capacity near 4.5 V decreases, and sufficient characteristics cannot be obtained. The layered lithium cobalt manganese oxide of the present invention has a uniform metal ion distribution and is particularly useful as a high voltage positive electrode active material for lithium batteries.

The layered lithium cobalt manganese oxide of the present invention can be obtained at a low temperature in a short time by the following second and third production methods of the present invention.

In the second production method of the present invention, a manganese salt, a cobalt salt and a sodium salt are mixed so that the molar ratio of manganese to cobalt is 45 to 55:55 to 45, and sodium is equimolar to the total of these. The aqueous solution contained therein is evaporated to dryness, and then the obtained solid is fired in an oxygen-containing gas at 700 to 900 ° C., and the obtained fired product is powdered with a lithium compound in a solid phase or an organic solvent. It is characterized by mixing and ion exchange at 140-400 ° C.

First, a manganese salt, a cobalt salt and a sodium salt are mixed at a molar ratio of manganese and cobalt of 45-55: 55-4.
5. Prepare an aqueous solution containing sodium in equimolar amounts with these, and evaporate to dryness.

As the manganese salt and cobalt salt used in the present invention, acetate, nitrate, oxalate and the like are preferably used, and as the sodium salt, carbonate, acetate, nitrate and oxalate, respectively. , Hydroxide and the like are preferably used. These salts are used alone or in combination of two or more as needed.

Specifically, it is preferable that the manganese salt, the cobalt salt, and the sodium salt are mixed so that the respective aqueous solutions have the above molar ratio. The concentration of the aqueous solution of these salts is not particularly limited, but is usually preferably about 5 to 20% by weight from the viewpoint of operability and economy. An aqueous solution containing these salts at a predetermined molar ratio is evaporated to dryness by an ordinary method using, for example, an evaporator such as a rotary evaporator.

Next, the solid particle powder obtained by evaporation to dryness is fired at 700 to 900 ° C. in an oxygen-containing gas, for example, air. If the firing temperature is lower than 700 ° C., cobalt and manganese do not form a solid solution, and it is difficult to obtain a powder having a uniform composition. On the other hand, if the sintering temperature exceeds 900 ° C., the energy required for the production becomes enormous. Further, since the grain growth becomes remarkable, it is difficult to completely exchange sodium ions and lithium ions in the next ion exchange step. The firing time is usually 2 to 20 hours, preferably
5 to 10 hours.

The obtained calcined product [for example, α-Na (Co _0.5 M
n _0.5 ) O ₂ ] is ground by a conventional method, and the obtained particle powder is mixed with a lithium compound in a solid phase or an organic solvent,
It is ion-exchanged at 140-400 ° C.

The organic solvent used in the present invention includes n-
Higher alcohols such as hexanol, ethoxyethanol, 2-2 ethoxyethoxyethanol or those with a boiling point of 14
An organic solvent of 0 ° C. or higher is preferably used because of good workability. These may be used alone or in combination of two or more as necessary. Further, as the lithium compound used in the present invention, carbonates, acetates, nitrates, oxalates, halides, n-butyllithium and the like are preferably used, and these may be used alone or in combination of two or more as necessary. Can be

As a preferred method, a lithium compound is dissolved in an organic solvent, and the particle powder of the fired product is dispersed in the solution. The concentration of the lithium compound in the organic solvent is
It is usually 3 to 10 mole percent, preferably 4 to 6 mole percent. The dispersion concentration of the particle powder of the fired product in the organic solvent is not particularly limited, but is preferably 1 to 20% by weight from the viewpoint of operability and economy.

The lithium compound used in the solid phase ion exchange reaction in the present invention includes nitrates, acetates, and the like.
Carbonates, halides, hydroxides and the like are used. These may be used alone or in combination of two or more as needed. As a preferred method, the lithium compound and the particle powder of the calcined product are mixed and compression-molded. The mixing ratio of the lithium compound and the particle powder of the calcined product is usually Li / (Co + Mn) = 2 to 2
0, preferably 5 to 10.

The ion exchange temperature is 140-400 ° C. When the ion exchange temperature is lower than 140 ° C., for example, sodium in α-Na (Co _0.5 Mn _0.5 ) O ₂ is not completely exchanged for lithium and remains in the layered structure. On the other hand, if the ion exchange temperature is higher than 400 ° C., the layered structure changes to a spinel structure, so that a uniform crystal structure cannot be obtained. The reaction time is generally 2-20 hours, preferably 5-5 hours.
8 hours. The particle powder obtained by ion exchange of sodium with lithium is, for example, filtered and washed with methanol or the like,
Thereafter, it is dried to obtain a layered lithium cobalt manganese oxide [eg, Li (Co _0.5 Mn _0.5 ) O ₂ ]. The drying method is not particularly limited, and a rotary evaporator, a spray dryer, or the like is used in addition to a normal drying method.

In the third production method of the present invention, the manganese salt and the cobalt salt are prepared by changing the molar ratio of manganese to cobalt to 45 to 55/55.
A precipitate is formed by mixing an aqueous solution containing oxalic acid in an amount equal to or greater than 45 with an aqueous solution of oxalic acid, and then filtering, washing, and drying the obtained precipitate. Pyrolyze at 350-500 ° C., and then mix the obtained particle powder and sodium compound so that the total of manganese and cobalt in the particle powder and sodium are equimolar, and the mixed powder contains oxygen. 700-900 ℃ in gas
And further, the obtained powdered particles are mixed with a lithium compound in a solid phase or an organic solvent,
It is characterized by ion exchange at ℃.

First, a precipitate is formed by mixing an aqueous solution containing a manganese salt and a cobalt salt such that the molar ratio of manganese to cobalt is 45 to 55/55 to 45 and an aqueous solution of oxalic acid in an equivalent amount or more. Let it. The above-mentioned manganese salts and cobalt salts are used. The concentrations of these salts and the aqueous solution of oxalic acid may be as described above. Specifically, a method is preferable in which an aqueous solution of oxalic acid of an equivalent amount or more is dropped into a mixed aqueous solution of an aqueous solution of a manganese salt and an aqueous solution of a cobalt salt to form a precipitate (composite of manganese oxalate and cobalt oxalate).

Next, the obtained precipitate is filtered, washed, dried and made into a powder, and then pyrolyzed at 350 to 500 ° C. in the air. Washing is preferably performed with water. The thermal decomposition temperature is 350
When the temperature is lower than 0 ° C, the oxalate does not sufficiently decompose thermally, so that a uniform powder cannot be obtained. On the other hand, the thermal decomposition temperature is 500
C. or lower is sufficient, and a thermal decomposition temperature exceeding this temperature is not industrial because it increases energy costs. The pyrolysis time is usually 2 to 10 hours, preferably 5 to 10 hours.

Next, the obtained particle powder is mixed so that the total of manganese and cobalt in the particle powder and sodium are equimolar, and is mixed in an oxygen-containing gas at 700 to 900 ° C.
Fired. If the firing temperature is lower than 700 ° C., cobalt and manganese do not form a solid solution, and it is difficult to obtain a powder having a uniform composition. On the other hand, if the sintering temperature exceeds 900 ° C., the energy required for the production becomes large. Further, since the grain growth becomes remarkable, it is difficult to completely exchange sodium ions and lithium ions in the next ion exchange step. The firing time is usually 5 to 20 hours, preferably 7 to 10 hours.

The obtained calcined product [for example, α-Na (Co _0.5 M
n _0.5 ) O ₂ ] is pulverized by a conventional method in the same manner as in the first embodiment of the present invention, and the obtained particle powder is mixed with a lithium compound in a solid phase or an organic solvent and ion-exchanged at 140 to 400 ° C. Thereafter, it is filtered and dried.

In the firing reaction described above, it is preferable that the solid particle powder or the mixed particle powder is subjected to compression molding and then fired. This makes it possible to obtain lithium cobalt manganese oxide particles having a more uniform composition. The density of the compact obtained by compression molding is preferably 2 g / ml or more. The upper limit of the density of the compact is usually 3.5 g / ml, preferably 2.5 g / ml, since the production becomes difficult if the density is too high. At this time, a small amount of water (1
(About 10% by weight), the strength of the molded body becomes sufficient and the handling becomes easy, and a lithium cobalt manganese oxide having more uniform composition can be obtained. The method of compression molding is not particularly limited, and a usual disk pelletizer, roller compactor, extruder or the like is used. The compact obtained by firing is pulverized into particle powder. The grinding method is not particularly limited, and a usual grinding method is used.

The layered lithium cobalt manganese oxide particles obtained by the present invention form a solid solution of the layered lithium manganese oxide and the layered lithium cobalt oxide having a uniform composition, and are used as a positive electrode active material of a lithium battery. When used, it has a high electromotive force, can have a high energy density, and has excellent reversibility to repeated charge and discharge, and is suitable as a positive electrode active material of a lithium battery.

[0036]

In general, the synthesis of an inorganic compound is carried out by a solid phase method, and the reaction at the time of firing is considered to proceed by mutual diffusion at the contact point between the raw material powder particles. When such a general oxide particle powder is used as a starting material, it is difficult to obtain a uniform mixture due to agglomeration of these particle powders, no matter how carefully the mixing operation is performed. In order to obtain a substance having a large solid capacity, it is necessary to repeat firing and pulverization. Furthermore, since alkali metals evaporate due to prolonged calcination, these are deficient and the composition is apt to change, so that stable quality particle powder cannot be obtained.

Compared to such a solid phase method, a powder obtained by selecting a water-soluble raw material as a starting raw material to form a solution, and drying the mixture is obtained by maintaining the mixed state of each element in an aqueous solution. Therefore, the uniformity is extremely excellent, and when such a powder is fired, the reaction is considered to be completed in a short time.

As a result of various studies, an aqueous solution containing a manganese salt, a cobalt salt, and a sodium salt was evaporated to dryness, and the solid particles were powdered in an oxygen-containing gas at 700 to 900%.
After baking at ℃, it was possible to complete the reaction in a short time by grinding. Furthermore, a layered lithium cobalt manganese oxide can be obtained by ion-exchanging a mixture of this and a lithium compound in a solid phase or an organic solvent, followed by filtration and drying.

In addition, the present inventors have found that, in the case of an alkali metal compound such as sodium and a cobalt manganese oxide, the melting point of the sodium compound is much lower than the melting point of the above-mentioned transition metal oxide, and the diffusion of sodium is higher than that of transition metal. It is easier than the diffusion of metal, and the reaction proceeds mainly by the diffusion of sodium into the transition metal oxide particles. We believe that it has become possible to carry out a natural reaction.

As a result of various studies, a manganese salt aqueous solution and an aqueous solution containing a cobalt salt were mixed with an aqueous solution of oxalic acid in an amount equal to or more than the equivalent to precipitate a complex of manganese oxalate and cobalt oxalate. After drying, if the cobalt manganese oxide synthesized by pyrolyzing the dried powder in air at a temperature in the range of 350 to 500 ° C. is used as a raw material, the reactivity with the sodium compound at the time of firing is improved, and It became possible to complete the reaction.

By using this composite as a raw material, the reason why the reactivity is improved and the reaction is completed in a short time is not clear yet, but the cobalt manganese oxide particle powder prepared by the method of the present invention is not clear. This is considered to be due to extremely high purity and extremely low impurity concentration. Furthermore, since cobalt and manganese maintain a state in an aqueous solution mixed in an ionic state, the uniformity of the composition is extremely excellent. Α-Na (Co
It is considered that particles having a uniform distribution of metal ions in _0.5 Mn _0.5 ) O ₂ can be generated. Further, after ion-exchanging the thus obtained mixture of α-Na (Co _0.5 Mn _0.5 ) O ₂ and a lithium compound in a solid phase or an organic solvent, the mixture is filtered and dried to form a layered lithium cobalt. It is considered that manganese oxide particles can be obtained.

In the present invention, when a layered lithium cobalt manganese oxide is obtained, for example, α-Na (Co _0.5 Mn
It is important to synthesize _0.5 ) O ₂ and exchange the sodium ions contained therein with lithium ions by ion exchange. If a lithium cobalt manganese oxide is to be synthesized directly by a solid-phase method or the like without using an ion exchange method, lithium manganese cobalt spinel oxide partially having a spinel-type crystal structure is produced as a by-product in the obtained powder. Cannot be obtained.

Furthermore, since the layered lithium cobalt manganese oxide obtained by the above method has a layered structure with extremely few defects, lithium ion diffusion between layers is good, and lithium ion insertion / desorption is performed. , The layered structure is kept stable. Therefore, when used as an electrode active material, a lithium battery having high current output characteristics and operating stably with repeated charge / discharge can be configured.

[0044]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 (Production of Lithium Cobalt Manganese Layered Oxide) A mixed aqueous solution containing manganese acetate, cobalt acetate and sodium carbonate at a mixing molar ratio of Mn / Co / Na = 1/1/2 (concentration of each aqueous solution) Was evaporated to dryness using a rotary evaporator, and the resulting solid particles were compressed with a disk pelletizer. Next, the molded product (molding density = 2.5 g)
/ ml) was calcined at 850 ° C for 10 hours in air and then pulverized. 15 g of the obtained particle powder [α-Na (Co _0.5 Mn _0.5 ) O ₂ ] was dispersed in 500 ml of a solution in which lithium bromide was dissolved at a concentration of 2 M in 2-2 ethoxyethoxyethanol. Thereafter, the suspension was heated and maintained at 150 ° C. for 6 hours, ion-exchanged sodium and lithium, and then filtered and washed with methanol.
Drying at 100 ° C. in the air gave layered lithium cobalt manganese oxide [Li (Co _0.5 Mn _0.5 ) O ₂ ] particles.

(Electrochemical Characteristics Evaluation Method) Next, the characteristics of the lithium cobalt manganese layered oxide particles obtained as described above as an electrode active material were evaluated. As a positive electrode for measurement, the layered oxide particles were mixed with 10% by weight of polytetrafluoroethylene as a binder and 30% by weight of acetylene black as a conductive material, and molded. A metal lithium foil was used as a negative electrode. As the electrolytic solution, a solution prepared by dissolving lithium phosphofluoride (LiPF ₆ ) at a concentration of 1 M in a propylene carbonate solvent was used.

An electrochemical measurement cell was constructed using the above-described positive working electrode, negative electrode, and electrolyte for measurement. Using this electrochemical measurement cell, a charge / discharge curve was examined in a potential range of 3.5 to 5.2 V, a current of 0.1 mA / cm ² and room temperature based on a lithium metal electrode. When the electric capacity of this charge and discharge was examined as the electrochemical characteristics of the layered oxide particle powder, the operating voltage was a high voltage of about 4.5 V, the initial discharge capacity was 110 mAh / g, and the capacity after 10 cycles was also It was 100 mAh / g, and almost no cycle deterioration was observed.

Example 2 A mixed aqueous solution of manganese sulfate aqueous solution and cobalt sulfate (Mn / C
o Molar ratio = 1/1) 2.0 equivalents of oxalic acid aqueous solution was added dropwise,
A composite of manganese oxalate and cobalt oxalate was precipitated, filtered, washed with water, and dried, and then the dried powder was thermally decomposed in air at 400 ° C. for 2 hours to prepare cobalt manganese oxide particles. Next, this cobalt manganese oxide particle powder and sodium carbonate were mixed (Mn / Co / Na = 1/1/2), fired at 850 ° C. for 10 hours in an oxygen-containing gas, and ground. The resulting particles _{[α-Na (Co 0. 5 Mn} 0.5) O 2 ] was 15g
Was dispersed in 500 ml of a solution of lithium bromide in a concentration of 2M in 2-2 ethoxyethoxyethanol, and the suspension was heated and maintained at 150 ° C. for 6 hours to ion-exchange sodium and lithium. After filtration and washing with methanol and drying in air at 100 ° C., a layered lithium cobalt manganese oxide [α-Li (Co _0.5 Mn _0.5 ) O ₂ ] was obtained. The characteristics of the lithium cobalt manganese layered oxide particles obtained as described above as an electrode active material were evaluated in the same manner as in Example 1. When the electric capacity of this charge and discharge was examined, the operating voltage was a high voltage of around 4.5 V, the initial discharge capacity was 100 mAh / g, and the capacity after 10 cycles was 98 mAh / g. I couldn't.

Comparative Example 1 Tricobalt tetroxide particles and dimanganese trioxide particles were mixed with sodium carbonate at a molar ratio of Co / Mn / Na of 1/1/2.
And dry-mixed so as to obtain compression molding (molding density = 2.5
g / ml) and calcined in air at 850 ° C. for 60 hours. After pulverizing the obtained sintered body, lithium bromide was used for 15 g of this powder.
Solution 2-2 dissolved in ethoxyethanol at a concentration of 2M 50
The suspension was heated and maintained at 150 ° C. for 6 hours, ion-exchanged between sodium and lithium, filtered and washed with methanol, and dried in air at 100 ° C. The characteristics of the lithium cobalt manganese layered oxide particles obtained as described above as an electrode active material were evaluated in the same manner as in Example 1. When the electric capacity of this charge and discharge was examined, the operating voltage was a high voltage of about 4.5 V, the initial discharge capacity was 63 mAh / g, and the capacity after 10 cycles was 54 mAh / g.
Cycle deterioration was observed.

[0050]

As described above, the layered rock salt type lithium cobalt manganese oxide particles of the present invention form a solid solution of layered lithium manganese oxide and layered lithium cobalt oxide having uniform compositions. When used as a positive electrode active material of a lithium battery, it has a high electromotive force, can have a high energy density, and has excellent reversibility to repetition of charge and discharge, and is suitable as a positive electrode active material of a lithium battery.

According to the production method of the present invention, the prepared cobalt manganese oxide particles have extremely high purity and extremely low impurity concentration, and further, cobalt and manganese are mixed in an ionic state. Since the state in the aqueous solution is maintained, the uniformity of the composition is extremely excellent. Due to this uniformity, for example, the obtained α
-Na (Co _0.5 Mn _0.5 ) O ₂ can produce particles with a uniform distribution of metal ions, and the α-Na (Co _0.5 Mn _0.5 ) O ₂ By ion-exchanging the mixture of compounds in a solid phase or an organic solvent, layered lithium cobalt manganese oxide particles can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page (71) Applicant 000003296 Denki Kagaku Kogyo Co., Ltd. 1-4-1, Yurakucho, Chiyoda-ku, Tokyo (72) Inventor Kazunori Takada 1-1-1, Namiki, Tsukuba, Ibaraki Pref. Inside the Materials Research Laboratory (72) Inventor Shigeo Kondo 1-1-1, Namiki, Tsukuba City, Ibaraki Prefecture Science and Technology Agency Inorganic Materials Research Laboratory (72) Inventor Wataru Watanabe 1-1-1, Namiki, Tsukuba City, Ibaraki Prefecture Science and Technology Agency In-house (72) Inventor Taro Inada 3-5-1 Asahicho, Machida-shi, Tokyo Denki Kagaku Kogyo Co., Ltd. Central Research Laboratory (72) Inventor Ryohisa Kajiyama 1-4-1, Meiji Shinkai, Otake-shi, Hiroshima Toda Kogyo (72) Inventor Masaru Takaguchi 1st institution, Nishino-sho, Inonoba-ba-cho, Minami-ku, Kyoto-shi, Japan F-term in the formula company (reference) 4G048 AA04 AB01 AB02 AB05 AB08 AC06 AD03 AD06 AE05 5H050 AA02 AA07 AA08 BA05 BA15 BA16 CA08 CA09 CB12 FA17 FA19 GA02 GA03 GA08 GA10 GA12 GA16 GA27 HA02 HA08 HA14

Claims (7)

[Claims] 1. A layered lithium cobalt manganese oxide particle powder comprising a solid solution of a layered lithium manganese oxide and a layered lithium cobalt oxide, wherein the molar ratio of cobalt to manganese is 45 to 55:55 to 45. . 2. The method of claim 1, wherein the metal ion distribution is uniform.
The layered lithium cobalt manganese oxide particles described in the above. 3. The layered lithium cobalt manganese oxide particles according to claim 1, which is used for a high voltage positive electrode active material of a lithium battery. 4. An aqueous solution containing manganese salt, cobalt salt and sodium salt in a molar ratio of manganese to cobalt of 45 to 55:55 to 45 and sodium in equimolar amount to the total thereof is evaporated to dryness. Then, the obtained solid particle powder is calcined in an oxygen-containing gas at 700 to 900 ° C., and the obtained calcined particle powder is mixed with a lithium compound in a solid phase or an organic solvent to obtain A method for producing layered lithium cobalt manganese oxide particles, characterized in that ion exchange is performed at 400 ° C. 5. Prior to firing, a solid particulate powder is
5. The process for producing layered lithium cobalt manganese oxide particles according to claim 4, wherein the compact is compacted into a compact having a compacting density of 3.5 g / ml. 6. A precipitate is formed by mixing an aqueous solution containing a manganese salt and a cobalt salt such that the molar ratio of manganese to cobalt is 45 to 55:55 to 45 and an oxalic acid aqueous solution in an equivalent amount or more. Then, the obtained precipitate is filtered, washed and dried, and the dried powder is dried in air at 350-500.
C., and then the obtained particle powder and sodium compound are mixed such that the total of manganese and cobalt in the particle powder and sodium are equimolar, and the mixed powder is mixed in an oxygen-containing gas. A layered lithium-cobalt-manganese oxide characterized by firing at 700 to 900 ° C, further mixing the obtained fired particle powder with a lithium compound in a solid phase or an organic solvent, and performing ion exchange at 140 to 400 ° C. Method for producing product particle powder. 7. Prior to firing, the mixed powder is added in an amount of 2 to 3.5 g / m
The method for producing layered lithium cobalt manganese oxide particles according to claim 6, which is compression-molded into a compact having a molding density of l.