JP2003272629A - Positive electrode active material for nonaqueous electrolyte secondary battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide lithium manganate particle powder with excellent charge/ discharge cycle characteristics of a secondary battery as a positive electrode active material for a nonaqueous electrolyte secondary battery. <P>SOLUTION: The positive electrode active material for the nonaqueous electrolyte secondary battery consisting of lithium manganate particle powder with an average primary particle size of 3.0 to 20.0 μm, an average secondary particle size D<SB>50</SB>of 2.5 to 40.0 μm, and a ratio between the average primary particle size and the average secondary particle size of 0.5 to 1.2, is obtained by neutralizing a reaction solution containing manganese salt, ageing it, and put it under oxidation reaction to obtain manganese oxide particle powder, which is mixed with a lithium compound, and heating the mixture within a temperature range of 700 and 1,000°C. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium manganate particle powder having excellent charge / discharge cycle characteristics of a secondary battery as a positive electrode active material for a non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art In recent years, portable and cordless electronic equipment such as AV equipment and personal computers are rapidly advancing, and there is a demand for a secondary battery having a small size, a light weight and a high energy density as a power source for driving them. It's getting higher. Under such circumstances, lithium ion secondary batteries, which have the advantages of high charge / discharge voltage and large charge / discharge capacity, have been receiving attention.

Conventionally, as a positive electrode active material useful for a high energy type lithium ion secondary battery having a voltage of 4V class, LiMn ₂ O ₄ having a spinel structure and L having a rock salt structure are used.
_{iMnO 2, LiCoO 2, LiCo 1} -X Ni
_{X O 2,} LiNiO ₂ or the like are generally known, inter alia although LiCoO ₂ is excellent in that it has a high voltage and high capacity, the manufacturing cost due to the supply amount of the cobalt material less problematic Ya Includes environmental safety issues for waste batteries. Therefore, research on spinel-structured lithium manganate particles (basic composition: LiMn ₂ O ₄ -hereinafter, the same-) produced from manganese with a large supply amount and low cost and good environmental friendliness has been actively conducted. There is.

As is well known, a lithium manganate particle powder can be obtained by mixing a manganese compound and a lithium compound in a predetermined ratio and firing the mixture in a temperature range of 700 to 800 ° C.

However, when the lithium manganate particles are used as the positive electrode active material of a lithium ion secondary battery, although they have high voltage and high energy density, they have a problem of poor charge / discharge cycle characteristics. The cause is
The crystal lattice expands and contracts due to the desorption / insertion behavior of lithium ions in the crystal structure due to the repeated charge / discharge, and the lattice change occurs due to the volume change of the crystal.
Is said to dissolve.

In a lithium ion secondary battery using lithium manganate particles, it is currently most required to suppress deterioration of charge / discharge capacity due to repeated charge / discharge and improve charge / discharge cycle characteristics. .

In order to improve the charge / discharge cycle characteristics, it is necessary that the positive electrode active material composed of lithium manganate particles is excellent in filling property and has an appropriate size. As the means, a method of controlling the particle size and the particle size distribution of lithium manganate particles, a method of controlling the firing temperature to obtain highly crystalline lithium manganate particles, and a heterogeneous element are added to strengthen the crystal bonding force. And a method of suppressing elution of Mn by performing surface treatment.

As a method for obtaining a lithium manganate particle powder having an appropriate size, JP-A-10-162826, JP-A-10-172567, and JP-A-10-3 can be used.
No. 21227, No. 11-1323, No. 11-45710, No. 11-71115, No. 11-219705, No. 2000
-12031, JP-A-2000-143247, JP-A-2001-122626, and JP-A-200
Each method described in JP-A 1-240417 is known.

[0009]

As a positive electrode active material for a non-aqueous electrolyte secondary battery, lithium manganate particles having excellent charge / discharge cycle characteristics of the secondary battery have not been obtained yet.

That is, the above-mentioned Japanese Patent Laid-Open No. 10-162826 discloses a method for producing lithium manganate particles having an excellent particle size distribution by a spray pyrolysis method.
Since the obtained lithium manganate particle powder is porous and has a large specific surface area, it becomes difficult to suppress the elution of Mn, and as a result, the charge / discharge cycle characteristics of the secondary battery deteriorate. Further, it is hard to say that the packing density is sufficient.

Further, Japanese Unexamined Patent Publication (Kokai) No. 10-172567 mentioned above discloses a manufacturing method in which a slurry of a manganese compound and a lithium compound is dried by a spray dryer and then calcined, but it is composed of a large number of primary particles. Since the agglomerates are formed and the specific surface area becomes large, it becomes difficult to suppress the elution of Mn, and as a result, the charge / discharge cycle characteristics of the secondary battery deteriorate. Further, it is hard to say that the packing density is sufficient.

Further, Japanese Patent Laid-Open No. 10-32127 discloses a lithium manganate particle powder in which the average particle size of primary particles and secondary particles is specified. However, since the primary particles are small, the secondary particles are Is composed of a large number of primary particles, and it becomes difficult to suppress the elution of Mn because the specific surface area becomes large, and as a result, the charge / discharge cycle characteristics of the secondary battery deteriorate. Further, it is hard to say that the packing density is sufficient.

Further, the above-mentioned JP-A-11-1323 describes a lithium manganate particle powder in which the average particle size of primary particles and secondary particles is specified, but it is an aggregate and has a specific surface area. Since it becomes large, it becomes difficult to suppress the elution of Mn, and as a result, the charge / discharge cycle characteristics of the secondary battery deteriorate. In the examples, the average primary particle diameter is 2.
Although a lithium manganate particle powder having a particle size of 0 μm and an average secondary particle size of 2.0 μm is described, it is difficult to say that the average particle size is small and the filling property is sufficient.

Further, Japanese Patent Application Laid-Open No. 11-45710 discloses a lithium manganate particle powder containing F, which is obtained by mixing and firing various raw materials. The primary particles of the particle powder are not considered, and it is difficult to say that the elution suppression of Mn and the filling property are sufficient.

Further, JP-A-11-71115 discloses a lithium manganate particle powder having an average agglomerated particle diameter of 1 to 50 μm and an average primary particle diameter of 3.0 μm or less. The average primary particle size of the lithium manganate particles obtained in 1. is as small as 1.0 μm or less and the specific surface area is large, so that it is difficult to suppress the elution of Mn, and as a result, the charge / discharge cycle characteristics of the secondary battery. Is reduced.

Further, the above-mentioned JP-A-11-219705 discloses a lithium manganate particle powder having a small content of fine particles having an average particle diameter of 1.0 μm or less, but primary particles are considered. However, the fact that electrolytic MnO ₂ is used as the manganese raw material and the specific surface area relative to the average particle size are large, so it is presumed that the particles are aggregated particles. Therefore, it is difficult to suppress the elution of Mn, and as a result, the charge / discharge cycle characteristics of the secondary battery deteriorate.

Further, the above-mentioned Japanese Patent Laid-Open No. 2000-12031 discloses a lithium manganate particle powder having an average particle diameter of 1 to 45 μm, but primary particles are not taken into consideration and the obtained manganese is obtained. Since lithium oxide particles are secondary particles formed by aggregating small primary particles, it is difficult to suppress the elution of Mn because of their large specific surface area, and as a result, the charge / discharge cycle characteristics of the secondary battery deteriorate.

Further, the above-mentioned Japanese Patent Laid-Open No. 2000-143247 discloses a lithium manganate particle powder having a primary particle diameter of 0.5 to 2.0 μm, but since the primary particles are small, the packing density is high. It becomes low and the specific surface area becomes large, so it becomes difficult to suppress the elution of Mn,
As a result, the charge / discharge cycle characteristics of the secondary battery deteriorate.

Further, the above-mentioned Japanese Patent Laid-Open No. 2001-122626 discloses a lithium manganate particle powder having a specified particle size distribution, but primary particles are not taken into consideration and electrolytic manganese dioxide ( EMD)
Alternatively, since CMD is used and the specific surface area relative to the average particle size is large, it is presumed that the particles are aggregated particles.
Therefore, it becomes difficult to suppress the elution of Mn, and as a result, the charge / discharge cycle characteristics deteriorate.

Further, the above-mentioned Japanese Patent Laid-Open No. 2001-240417 discloses a manufacturing method in which manganese hydroxide is oxidized into manganese oxide, particles are grown, and then mixed with a lithium compound, followed by heating and firing. However, since the obtained lithium manganate particles have a large specific surface area, it is difficult to suppress the elution of Mn, and as a result, the charge / discharge cycle characteristics of the secondary battery deteriorate. Also, since it is hydrothermally synthesized, it cannot be said to be industrial.

Therefore, it is a technical object of the present invention to provide a lithium manganate particle powder having excellent charge / discharge cycle characteristics of a secondary battery as a positive electrode active material for a non-aqueous electrolyte secondary battery.

[0022]

The above technical problems can be achieved by the present invention as follows.

That is, in the present invention, the average primary particle size is 3.0.
.About.20.0 μm and the average secondary particle diameter D ₅₀ (the particle diameter at which the cumulative proportion with respect to the particle diameter when the total volume of the lithium manganate particle powder is 100% is 50%) is 2. From 5 to 40.0 μm, and the ratio of the average primary particle diameter to the average secondary particle diameter (average primary particle diameter / average secondary particle diameter) is 0.5 to 1.2. And a positive electrode active material for a non-aqueous electrolyte secondary battery.

Further, according to the present invention, the cumulative ratio when D ₁₀ (the total volume of the lithium manganate particle powder is 100% and the cumulative ratio with respect to the particle diameter is calculated with respect to the average secondary particle diameter D ₅₀ of the lithium manganate particle powder) particles but expressed in cumulative volume on the total volume of the ratio _(D 10 _/ D _{5 0)} a is 0.50 or more _{D 90} for _{D 50} (lithium manganate particles having a particle diameter) comprising 10% 100% The ratio of the particle diameter at which the cumulative proportion when the diameter is obtained is 90% (D
₉₀ / _{D 50)} is a positive active material for the nonaqueous electrolyte secondary battery is 2.0 or less.

In the present invention, the reaction solution containing a manganese salt is neutralized and then aged, and then an oxidation reaction is carried out to obtain manganese oxide particle powder, and the manganese oxide particle powder and a lithium compound are mixed. , 100 to 100 of the mixture
The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery is characterized by heating in a temperature range of 0 ° C.

Next, the structure of the present invention will be described in more detail.

First, the positive electrode active material for a non-aqueous electrolyte secondary battery according to the present invention (hereinafter, simply referred to as "positive electrode active material") will be described.

In the present invention, the term "primary particle" means the smallest particle that can exist alone, and the term "secondary particle" means that a plurality of primary particles are aggregated to behave normally. Means the smallest particle of.

The positive electrode active material according to the present invention has an average primary particle diameter of 3.0 to 20.0 μm. When the average primary particle size is less than 3.0 μm, the packing density becomes low when the positive electrode of the secondary battery is manufactured, and it is necessary to increase the amount of the binder, which lowers the energy density of the secondary battery. Invite. On the other hand, when it exceeds 20.0 μm, the Li insertion / removal reaction tends to decrease when the current density is increased. It is preferably 4.0 to 18.0 μm.

The average secondary particle diameter (D ₅₀ ) of the positive electrode active material according to the present invention is 2.5 to 40.0 μm. When the average secondary particle size is less than 3.0 μm, the packing density becomes low when the positive electrode of the secondary battery is manufactured, and it is necessary to increase the binder amount. Cause decline. On the other hand, when it exceeds 20.0 μm, the Li insertion / removal reaction tends to decrease when the current density is increased. The thickness is preferably 5.0 to 30.0 μm.

Ratio of the average primary particle diameter to the average secondary particle diameter (D ₅₀ ) (average primary particle diameter / average secondary particle diameter)
Is 0.5 to 1.2, and when it is less than 0.5, the packing density is lowered due to the large number of aggregated particles, and when it is 1.0, the particle diameters of the primary particles and the secondary particles are The particles are the same and do not aggregate but behave as primary particles, but the upper limit is 1.2 in consideration of measurement error. It is preferably 0.5 to 1.0.

Manganese by laser scattering / diffraction system
The total volume of lithium oxide particle powder is 100%
When the cumulative ratio of the volume to the
The particle diameters at 10%, 50%, and 90% are D
_10,D_Fifty, D₉₀, The present invention
The particle size distribution of the positive electrode active material is the average secondary particle diameter D._FiftyAgainst
D₁₀Ratio of (D₁₀/ D_Fifty) Is 0.50 or more
D_FiftyAgainst D_{9 0}Ratio of (D₉₀/ D_Fifty) Is 2.
It is 0 or less. D₁₀/ D_FiftyAnd D₉₀/ D _FiftyBefore
Outside the range, it means that the particle size distribution is wide.
Therefore, the filling property decreases. D₁₀/ D_FiftyIs 0.6 or more
It is more preferably 0.64 or more. Moreover
The limit value is about 0.85. Also, D₉₀/ D_FiftyIs
It is preferably 1.7 or less, more preferably 1.6 or less.
It The lower limit is about 1.15.

The particle shape of the positive electrode active material according to the present invention is granular. In the case of a particle shape having an acute angle portion, reactivity with an electrolytic solution increases, which is not preferable.

The positive electrode active material according to the present invention is Li _{1 + x} Mn.
It is a lithium manganate particle powder represented by a composition formula of _2- xO ₄ , and Li / Mn is a molar ratio of 0.525 to 0.6.
It is preferably 2. If less than 0.525,
Although the charge / discharge capacity is high, the cycle characteristics deteriorate due to the occurrence of strain due to the John-Teller effect. Also, 0.
If it exceeds 62, the initial discharge capacity is not sufficient, which is not preferable. In the above composition formula, the atomic number is 11
You may contain the said metal element or transition metal element by 0-20% by molar ratio with respect to Mn.

It should be noted that Mn ₂ O ₃ , Mn ₃ O ₄ , MnO _{2 and} Li ₂ Mn which do not contribute to the charge / discharge capacity and cycle characteristics.
It may contain a foreign phase such as O ₃ .

The BET specific surface area value of the positive electrode active material according to the present invention is preferably 0.04 to 1.5 m ² / g. 0.04
When it is less than m ² / g, the Li insertion / desorption reaction is considered to decrease when the current density is increased, and the battery characteristics deteriorate. When it exceeds 1.5 m ² / g, the packing density of the positive electrode active material decreases and the reactivity with the electrolytic solution becomes excessive, so that the safety decreases.

The tap density of the positive electrode active material according to the present invention is preferably 2.0 g / ml or more. The upper limit is 3.0g
/ Ml.

Next, the method for producing the positive electrode active material according to the present invention will be described.

Examples of the manganese salt in the present invention include manganese sulfate, manganese nitrate, manganese oxalate, manganese acetate, etc. These may be used alone or in combination of two or more as required.

When the reaction solution containing various manganese salts described above is neutralized, an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide or an alkaline solution such as ammonia can be used. Manganese oxide having a large particle size can be easily obtained by adding an alkaline solution in excess of the equivalent amount of manganese salt. The addition amount of the alkaline solution excluding the neutralized portion of the manganese salt is 0 to 20 mol / L.
Can be carried out in the following manner, and preferably 1.0 to 10 mol / L.

The aging reaction is carried out in a temperature range of 20 to 100 ° C., preferably 50 to 90, with respect to the suspension after the neutralization reaction.
Perform in the temperature range of ° C. By carrying out the aging reaction, manganese oxide having a narrow particle size distribution can be obtained, and thus a lithium manganate particle powder having a narrow particle size distribution can be obtained. The aging time is preferably 0.1 to 10 hours, more preferably 1 to 3 hours.

The oxidation reaction can be carried out by passing an oxidizing gas through the reaction solution or by adding an oxidizing agent, for example, aeration of air is preferable.

After completion of the oxidation reaction, washing with water and drying are performed to obtain manganese oxide particle powder.

The obtained manganese oxide particle powder is Mn ₃ O.
₄ and the particle shape is granular, and the average particle diameter is 2.
0 to 20.0 μm, BET specific surface area value is 0.04
It is preferably about 2.0 m ² / g. Also, Mn ₂
It may contain O ₃ .

As the lithium raw material, lithium carbonate, lithium hydroxide, lithium nitrate, lithium chloride and the like can be used, but lithium carbonate is preferred.

The manganese oxide particle powder and the lithium raw material are mixed in a molar ratio of Li / Mn = 0.525 to 0.6.
It is preferably about 2. When it is 0.525 or less, the capacity is high, but the charge-discharge cycle characteristics deteriorate due to the occurrence of strain due to the John-Teller effect. Also, 0.
If it exceeds 62, the initial capacity is not sufficient.

The manganese oxide particle powder and the lithium raw material must be in a uniform mixed state. If they are not mixed homogeneously, the composition ratio will be partially shifted, and lithium manganate having different capacities and reversibility will be synthesized, and it will also be a cause of generation of a different phase other than lithium manganate.

The firing temperature of the mixture is 700 to 1000 ° C. When the temperature is lower than 700 ° C., lithium manganate particles having high crystallinity cannot be obtained. 10
At a temperature of 00 ° C. or higher, the average particle size of the primary particles becomes too large and it becomes difficult for Li ions to be de-inserted.

The firing atmosphere may be an oxygen-containing gas such as air. The firing time may be selected so that the reaction proceeds uniformly, but is preferably 1 to 48 hours, more preferably 10 to 24 hours.

After firing, the powder is pulverized to obtain lithium manganate particles.

When a positive electrode material is manufactured by using the lithium manganate particles according to the present invention as a positive electrode active material for a non-aqueous electrolyte secondary battery, a conductive agent such as acetylene black or carbon black and polytetrafluorocarbon are used. ethylene,
It is mixed with a binder such as polyvinylidene fluoride and molded into a predetermined shape to obtain a positive electrode material.

The negative electrode active material is not particularly limited,
For example, a lithium metal, a lithium alloy, a substance capable of inserting and extracting lithium can be used, and examples thereof include a lithium / aluminum alloy, a lithium / tin alloy, graphite, and graphite.

The electrolyte is also not particularly limited, but for example, in at least one organic solvent such as carbonates such as propylene carbonate, diethyl carbonate, dimethyl carbonate and ethers such as dimethoxyethane, lithium perchlorate, tetrafluoride and tetrafluoride are used. What melt | dissolved at least 1 sort (s) of lithium salt, such as lithium borate and lithium hexafluorophosphate, can be used.

The secondary battery manufactured using the positive electrode active material according to the present invention has an initial discharge capacity of 85 to 135 mAh / g,
The capacity retention rate after 50 cycles at 60 ° C. is 93% or more.

[0055]

BEST MODE FOR CARRYING OUT THE INVENTION A typical embodiment of the present invention is as follows.

The particle size of the positive electrode active material was measured by the following two methods.

Laser scattering / diffraction system "NIKKISO
  MICROTRAC HRA, MODEL9320-
X100: manufactured by Nikkiso Co., Ltd.
Of secondary particles from the particle size distribution of₁₀, D_Fifty, D₉₀Measure
Decided Average secondary particle size is D _FiftyThe value of

The average primary particle diameter was measured with a scanning electron microscope (manufactured by Hitachi Ltd.). Ten primary particles were arbitrarily selected from the particles existing on the diagonal line of the scanning electron microscope photograph, the particle size was measured, and the average value was defined as the average primary particle size. In the scanning electron micrograph, a magnification at which 20 to 40 particles are present on the diagonal line is preferable from the viewpoint of measuring accuracy of the particle size.

The positive electrode active material was identified and its crystal structure and crystallite size were determined by X-ray diffraction (RIGAKUCu-Kα 40k).
V 40 mA).

The morphology of the precursor particles was observed with a scanning electron microscope (Hitachi Ltd.).

The BET specific surface area was measured by the BET method.

The tap density is "SEISHIN TAP".
DENSER KYT-3000: manufactured by Seishin Enterprise Co., Ltd. ”.

<Production of Positive Electrode> Lithium manganate particle powder, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed at a weight ratio of 85: 10: 5, and N-methyl-2- Pyrrolidone was added to form a paste, the paste was applied to an aluminum foil with a thickness of 0.15 mm, dried and punched into a disk having a diameter of 16 mm to produce a positive electrode.

Lithium foil was used for the negative electrode,
It was punched into a disk shape of m.

<Preparation of Secondary Battery> The separator was made of polyethylene and was punched into a 19 mm disk shape. The electrolyte used was a mixture of ethylene carbonate (EC) with LiPF ₆ as a supporting salt and diethyl carbonate (DEC) at a volume ratio of 1: 1. Then, a coin-type cell battery was manufactured in a glove box in an argon atmosphere.

In the charge / discharge cycle test of the secondary battery, the current density with respect to the positive electrode was 0.
After charging / discharging was repeated 50 cycles at a temperature of 60 ° C. at a cutoff voltage of 4.5 V to 3.0 V at 5 mA / cm ² , the discharge capacity was measured and the ratio to the initial discharge capacity was obtained.

<Production of Lithium Manganese Oxide Particle Powder> 0.5 mol of 3.5 mol sodium hydroxide was added under nitrogen aeration.
Molar manganese sulfate was added to make the total amount 1 L, and the obtained manganese hydroxide was aged at 90 ° C. for 1 hour. After aging, air was ventilated to oxidize at 90 ° C., and after washing with water and drying, manganese oxide particle powder was obtained.

The obtained manganese oxide particle powder was Mn ₃ O.
₄ , the particle shape is granular, and the average particle diameter is 4.8 μm.
m, BET specific surface area was 0.6 m ² / g.

The Mn ₃ O ₄ particle powder and lithium carbonate were mixed for 1 hour at a Li / Mn ratio of 0.55 to obtain a uniform mixture. 50 g of the obtained mixture was put in an alumina crucible and kept in an air atmosphere at 750 ° C. for 10 hours to obtain lithium manganate particles. The obtained lithium manganate particle powder was crushed with a ball mill for 1 hour.

The obtained lithium manganate particles had an average primary particle diameter of 5.0 μm and an average secondary particle diameter (D
₅₀ ) 7.0 μm, the average primary particle diameter / average secondary particle diameter is 0.71, D ₁₀ / D ₅₀ is 0.74, D ₉₀ / D ₅₀ is 1.39, and BET The specific surface area value was 0.4 m ² / g and the tap density was 2.1 g / ml. The observation result of the scanning electron micrograph of the obtained lithium manganate particle powder is shown in FIG. As shown in the figure, the particle shape was granular without sharp corners.

The coin-type battery prepared by using the positive electrode active material composed of the lithium manganate particles powder obtained here had an initial discharge capacity of 120 mAh / g and a capacity retention rate of 97% / after 50 cycles at 60 ° C. It was 50 cycles.

[0072]

The most important point in the present invention is that the positive electrode active material according to the present invention has a large primary particle size and is excellent in dispersibility without agglomeration.

In the present invention, a manganese oxide particle having a uniform particle size distribution and large size is obtained by providing a aging step after neutralizing the manganese salt and performing an oxidation reaction at a high alkali and a high temperature. be able to.

Since the particle size of the lithium manganate particles largely depends on the particle size of the manganese oxide particles used as the precursor, by using the manganese oxide particles, the positive electrode active material composed of the lithium manganate particles is also a large primary particle. The particle size distribution is also excellent.

The secondary battery using the positive electrode active material according to the present invention has excellent charge / discharge cycle characteristics because the positive electrode active material has a small specific surface area and is in the form of particles having no sharp corners. Therefore, it is presumed that this is because the reactivity with the electrolytic solution is suppressed, and the dispersibility and filling property at the time of forming a coating are excellent.

[0076]

EXAMPLES Next, examples and comparative examples will be shown.

Examples 1 to 6: In Example 1, the reaction temperature was 80.
Except for the temperature was set in the same manner as in the embodiment of the invention,
Lithium manganate particles were obtained. In Example 2, lithium manganate particles were obtained in the same manner as in the embodiment of the present invention except that the amount of sodium hydroxide added was 4.0 mol. Lithium manganate particles were obtained in the same manner as in Example 2 except that the Li / Mn ratio was changed to 0.60. In Example 4, lithium manganate particles were obtained in the same manner as in Example 2 except that the ball mill crushing time was 20 minutes. In Example 5, lithium manganate particle powder was obtained in the same manner as in the embodiment of the present invention except that the amount of sodium hydroxide added was 6.0 mol. In Example 6, lithium manganate particles were obtained in the same manner as in Example 5 except that the ball mill crushing time was 20 minutes.

Comparative Examples 1 to 4 As Comparative Example 1, lithium manganate particle powder was obtained in the same manner as in the embodiment of the present invention except that electrolytic MnO ₂ was used in place of the precursor Mn ₃ O ₄ particles. Got As Comparative Example 2, lithium manganate particle powder was obtained in the same manner as the embodiment of the present invention except that the amount of sodium hydroxide added was 1.05 mol. As Comparative Example 3, the aging and oxidation reaction temperatures were set to 60.
Lithium manganate particles were obtained in the same manner as in Comparative Example 2 except that the temperature was changed to ° C. As Comparative Example 4, lithium manganate particles were obtained in the same manner as Comparative Example 2 except that the amount of sodium hydroxide added was 2.0 mol.

The production conditions at this time are shown in Table 1, and various characteristics of the obtained lithium manganate particles and the results of battery evaluation conducted in the same manner as the embodiment of the invention are shown in Table 2.

[0080]

[Table 1]

[0081]

[Table 2]

As is clear from Table 2, the batteries of Comparative Examples 1 to 4 had a large deterioration in capacity during charge / discharge cycles, whereas the batteries of the embodiment of the invention and Examples 1 to
In each of the batteries of No. 6, deterioration of the capacity was suppressed, and a better charge / discharge cycle maintenance rate was shown. Further, the packing density is low in Comparative Examples 1 to 4, whereas it is higher than 2.0 g / ml in the embodiments and Examples 1 to 6 of the present invention, showing a good packing density. It is considered that this is because the particles are large particles and have good dispersibility, and thus have a small specific surface area and are granular.

[0083]

Since the positive electrode active material according to the present invention has excellent dispersibility and filling properties, it is possible to provide a non-aqueous electrolyte secondary battery having excellent charge / discharge cycle characteristics.

[Brief description of drawings]

FIG. 1 is an electron micrograph (15) of a positive electrode active material composed of lithium manganate particles obtained according to an embodiment of the invention.
00 times).

FIG. 2 shows an electron micrograph (3500 times) of the lithium manganate particles powder produced in Comparative Example 1.

FIG. 3 shows an electron micrograph (30000 times) of the lithium manganate particles powder produced in Comparative Example 3.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideaki Maeda             1-1-1 Shinoki, Onoda City, Yamaguchi Prefecture             Industrial Co., Ltd. Onoda Factory (72) Inventor Hideaki Sadamura             1-1-1 Shinoki, Onoda City, Yamaguchi Prefecture             Industrial Co., Ltd. Onoda Factory F-term (reference) 4G048 AA04 AB02 AB06 AC06 AD04                       AD06 AE05                 5H029 AJ05 AK03 AL07 AL12 AM03                       AM04 AM05 AM07 CJ02 CJ08                       CJ11 CJ14 DJ16 EJ04 EJ12                       HJ05 HJ14                 5H050 AA07 BA16 BA17 CA09 CB08                       CB12 EA10 EA24 FA17 GA02                       GA10 GA14 GA15 HA05 HA14

Claims (3)

[Claims] 1. The average primary particle diameter is 3.0 to 20.0 μm.
And the average secondary particle diameter D ₅₀ (the particle diameter at which the cumulative proportion with respect to the particle diameter is 50% when the total volume of the lithium manganate particle powder is 100%) is 2.5 to 40. And a ratio of the average primary particle diameter to the average secondary particle diameter (average primary particle diameter / average secondary particle diameter) of 0.5 to 1.2, which is composed of lithium manganate particle powder. A characteristic positive electrode active material for a non-aqueous electrolyte secondary battery. Cumulative percentage of time of obtaining the cumulative ratio wherein the particle diameter on the total volume of the D _{10 (lithium} manganate particles to the average secondary particle diameter D ₅₀ of the lithium manganate particles as 100% and 10% Ratio (D ₁₀ / D _{5 0} ) of 0.50 or more and the total volume of D ₉₀ (lithium manganate particle powder) to D ₅₀ is 1
The ratio (D ₉₀ / D ₅₀ ) of the particle diameter at which the cumulative proportion is 90% when the cumulative proportion is calculated as 00%.
Is 2.0 or less, The positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1. 3. A manganese salt-containing reaction solution is neutralized and then aged, and then an oxidation reaction is performed to obtain manganese oxide particle powder. The manganese oxide particle powder and a lithium compound are mixed, and the mixture is mixed. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein heating is performed in a temperature range of 700 to 1000 ° C.