JP2000294242A - Positive electrode active material for nonaqueous electrolyte secondary battery, manufacture therefor and nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a positive electrode active material in a wide voltage range, to enhance capacity, and to improve charge/discharge cycle durability by constituting the positive electrode active material of Li, Mn, O having a monoclinic crystal layer-shaped rock salt type structure and having a specific composition and one or more kinds of four kinds of metallic elements besides Al. SOLUTION: This positive electrode active material is expressed by LixMnyM1-yO2. Here, M is one or more kinds of Al, Fe, Co, Ni and Cr, and (0<x<=1.1 and 0.5<=y<1) are realized. When manufacturing this active material, an Mn compound and a compound including an element M are water heat- treated at 130 to 300 deg.C in a strong basic aqueous solution including an Li element. In this case, lithium hydroxide is desirable as an Li compound included in the strong basic aqueous solution. When the Mn compound and the compound including the element M are included in this strong basic aqueous solution after being formed as hydroxide, oxide or oxyhydroxide particularly obtained by coprecipitation, a positive electrode active material by uniformly distributing Mn and the element M can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery and a method for producing the same. Further, the present invention relates to a non-aqueous electrolyte secondary battery having the active material.

[0002]

2. Description of the Related Art In recent years, as devices have become more portable and cordless, expectations for small, light-weight, high energy density non-aqueous electrolyte secondary batteries have increased. Positive electrode active materials for nonaqueous electrolyte secondary batteries include LiCoO ₂ , Li
Composite oxides of lithium and transition metals such as NiO ₂ , LiMn ₂ O ₄ , and LiMnO ₂ are known. Development of a high-voltage, high-energy-density non-aqueous electrolyte secondary battery combining these positive electrode active materials and a negative electrode active material such as a carbon material capable of inserting and extracting lithium has been promoted. In particular, research on lithium and manganese composite oxides using inexpensive material manganese has been particularly advanced recently.

In general, a positive electrode active material used for a non-aqueous electrolyte secondary battery is composed of a composite oxide of lithium and a transition metal such as cobalt, nickel, and manganese. The electrode characteristics such as performance and operating voltage are different.

For example, LiCoO ₂ and LiNi _0.8 C
In a nonaqueous electrolyte secondary battery using a composite oxide having a layered rock salt type structure such as o _0.2 O ₂ as a positive electrode active material, the capacity densities are 140 to 160 mAh / g and 190 to 210 mAh / g, respectively.
g and a high reversibility to occlusion and release of lithium in a high voltage range of 2.5 to 4.3 V. However, there is a problem that cobalt or nickel as a raw material is expensive, and that lithium does not occlude and release reversibly in a voltage range of 2 V or less.

On the other hand, a non-aqueous electrolyte secondary battery using a spinel-type composite oxide composed of LiMn ₂ O _{4 made of} relatively inexpensive manganese as a positive electrode active material has a capacity density of 100 to 100%.
It is 120 mAh / g, which is lower than that of the active material containing cobalt or nickel. In addition, there is a problem that the charge / discharge cycle durability is low, and that the battery deteriorates rapidly in a low voltage region of less than 3 V. On the other hand, a non-aqueous electrolyte secondary battery using LiMnO ₂ , which also uses manganese as a raw material, as an active material,
Since it can operate up to a low voltage range of about 2 V, LiMn ₂
Although a capacity higher than O ₄ can be expected, there is a problem that the charge / discharge cycle durability is lower than that of LiMn ₂ O ₄ .

[0006] Examples of the LiMnO _2, monoclinic LiMnO ₂ of layered rock salt-type structure has been known to be orthorhombic LiMnO ₂ and α-NaMnO ₂ type structure of β-NaMnO ₂ type structure. Since orthorhombic LiMnO ₂ is gradually transformed into a spinel phase by repeated charge and discharge, the charge and discharge cycle durability is extremely low.

[0007] Monoclinic LiMnO ₂ is synthesized by ion-exchanging α-NaMnO ₂ synthesized by a normal solid-state reaction method in a non-aqueous solution containing Li ions at a temperature of 300 ° C. or less (ARArmstrong and PGBruce, NATURE, V
ol. 381, P499, 1996). It has also been reported that manganese oxide is synthesized by hydrothermal treatment in a lithium salt aqueous solution containing a hydroxide of an alkali metal other than lithium (JP-A-11-21128). However, when the monoclinic LiMnO ₂ synthesized by these methods is used as the positive electrode active material, although the charge / discharge cycle durability is improved, the LiCl
Compared with a non-aqueous electrolyte secondary battery using CoO ₂ , LiNi _0.8 Co _0.2 O ₂ or the like as a positive electrode active material, the charge-discharge cycle durability was inferior, and it was difficult to adopt it in a practical battery.

[0008] On the other hand, Fe to LiMnO _2, Ni, Co,
A composite oxide to which Cr or Al has been added is disclosed in JP-A-10-13.
4812, all of the composite oxides are recognized as having an orthorhombic LiMnO ₂ structure because their X-ray diffraction charts are similar to 35-749 of JCPDS. Is not enough.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an inexpensive positive electrode active material for a non-aqueous electrolyte secondary battery which can be used in a wide voltage range, has a large electric capacity, is excellent in charge / discharge cycle durability, and is inexpensive. , And a method for producing the same. It is another object of the present invention to provide a non-aqueous electrolyte secondary battery having a high energy density using the positive electrode active material.

[0010]

The present invention SUMMARY OF] has a monoclinic layered rock-salt structure, Li _x Mn _y represented by M _1-y O ₂ (however, M is Al, Fe, Co, One or more elements selected from the group consisting of Ni and Cr, 0 <x ≦ 1.1,
0.5 ≦ y <1. The present invention provides a positive electrode active material for a non-aqueous electrolyte secondary battery, a method for producing the same, and a non-aqueous electrolyte secondary battery having the positive electrode active material.

[0011] _{Li x Mn y M 1-y} O 2 can take two kinds of structure of the orthorhombic and monoclinic as a crystal structure, but in the present invention has a layered rock-salt structure of monoclinic I have. When the monoclinic one is used as the positive electrode active material of the nonaqueous electrolyte secondary battery, the charge / discharge cycle durability is excellent. However, in the present invention, Li
_{x Mn y M 1-y O} 2 is not composed of only monoclinic, it may coexist those slight orthorhombic.

In the present invention, in _{Li x Mn y M 1-y} O 2 is 0.5 ≦ y <1. If y is less than 0.5, the monoclinic layered rock salt structure cannot be maintained. Preferably 0.65
≦ y ≦ 0.99 is adopted. M is Al, Fe,
At least one element selected from the group consisting of Co, Ni, and Cr is preferable. Particularly, Al is preferable because the electric capacity of the nonaqueous electrolyte secondary battery using the positive electrode active material of the present invention increases.

[0013] In the production method of the present invention, the Li _x Mn _y M
Manganese compound (hereinafter referred to as Mn source material) in a strongly basic aqueous solution containing lithium element to obtain _1-y O ₂
And a compound containing the element M (hereinafter, referred to as an M source material)
Hydrothermal treatment is performed at 30 to 300 ° C. As a method of adding the Mn source material and the M source material to the strong basic aqueous solution, the following two methods are preferably adopted. 1) The Mn source material and the M source material are uniformly mixed in advance and then added. 2) M is added to a strong basic aqueous solution containing lithium element.
The source material is dissolved, and the Mn source material is added to the aqueous solution.

According to the method 1), it is preferable that Mn and M are easily distributed uniformly in the obtained positive electrode active material. In particular, when a hydroxide, oxide or oxyhydroxide obtained by co-precipitating the Mn source material and the M source material is contained in the strong basic aqueous solution, Mn and M are more uniformly distributed. It is preferred. In the method 2), since the M source material is dissolved in the aqueous solution and easily reacts with the Mn source material, Mn and M are uniformly distributed in the obtained positive electrode active material.

When M is Al, the method 2) is preferable. When NaAlO ₂ , KAlO ₂ , LiAlO ₂ or the like is used as a raw material and dissolved in a strongly basic aqueous solution, homogeneous LiMn _x
Al _{1 -xO 2} is preferable because it can be synthesized.

Further, in the production method of the present invention, the lithium element contained in the strongly basic aqueous solution is converted from a water-soluble lithium compound into a strongly basic aqueous solution in view of workability and uniformity of the crystal of the obtained composite oxide. It is preferable that the compound is dissolved in the aqueous solution to be dissolved, and as the lithium compound, lithium hydroxide is particularly preferable.

The strongly basic aqueous solution of the present invention has a pH of 1
It is preferably one or more. The strongly basic aqueous solution preferably contains a hydroxide of an alkali metal other than lithium. Potassium hydroxide or sodium hydroxide is particularly preferable since impurities hardly remain in the obtained positive electrode active material. Potassium hydroxide and sodium hydroxide may be used alone or as a mixture. The strongly basic aqueous solution may contain, as anions, chlorine ions, bromine ions, nitrate ions, acetate ions, oxalate ions, etc., in addition to hydroxyl ions.

In the production method of the present invention, the Mn source raw materials include oxides (Mn ₂ O ₃ , MnO, MnO _{2 and the} like), oxide hydrates, oxyhydroxides and the like. Is preferable. These M
The n-source materials may be used alone or as a mixture of two or more.

In the production method of the present invention, as the M source material, metal M, hydroxide, oxide, oxyhydroxide, chloride, nitrate and the like are used. These M source materials may be used alone or in combination of two or more.

The production method of the present invention includes, for example, pure water 1
A strong basic aqueous solution is prepared by dissolving 0.05 to 5 mol of a lithium compound such as lithium hydroxide and lithium chloride and 5 to 100 mol of a hydroxide of an alkali metal other than lithium per kg. Next, the Mn source material and the M source material are added to and mixed with the aqueous solution, and the resulting mixture is placed in a hydrothermal reactor such as an autoclave and subjected to a hydrothermal reaction. The hydrothermal reaction conditions are usually 0.1 to 130 ° C. to 300 ° C.
Preferably, the reaction is carried out for 5 hours to 14 days, especially 20 hours.
The reaction is preferably performed at a temperature of 0 to 250 ° C for 1 to 48 hours.

In the production method of the present invention, the strongly basic aqueous solution 1
Usually, about 0.1 to 10 g of the Mn source material is preferably added to 00 mL, particularly preferably 0.5 to 3 g. Further, it is preferable to add about 0.02 to 5 g of the M source material, and it is particularly preferable to add 0.1 to 1 g.

After the completion of the hydrothermal reaction, the reaction product is washed with ethanol, filtered, and dried to remove the remaining unreacted raw materials such as lithium hydroxide, sodium hydroxide, and potassium hydroxide. _{Li x Mn y M 1-y} O 2 monoclinic layered rock-salt structure.

The positive electrode of the non-aqueous electrolyte secondary battery of the present invention is a molded article containing the above-mentioned positive electrode active material, conductive material and binder.
As the binder, polyvinylidene fluoride, polytetrafluoroethylene (hereinafter, referred to as PTFE), polyamide, carboxymethyl cellulose, acrylic resin and the like are preferable. As conductive materials, acetylene black, graphite,
A carbon-based conductive material such as Ketjen Black is preferred.
A slurry comprising a mixture of the positive electrode active material, the conductive material and the binder, and a solvent capable of dissolving or dispersing the binder, or a kneaded product obtained by adding an organic solvent to the mixture and kneading the mixture, aluminum foil, stainless steel foil It is preferable that the positive electrode is coated or supported on a positive electrode current collector such as the above to form a positive electrode.

In the non-aqueous electrolyte secondary battery of the present invention, the solvent of the electrolyte is preferably a carbonate ester. Carbonate can be used either cyclic or chain. Examples of the cyclic carbonate include propylene carbonate and ethylene carbonate. Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate and the like. In the present invention, it is preferable to use the above carbonate alone or as a mixture of two or more thereof, and the above carbonate may be used as a mixture with another solvent.

In addition, depending on the material of the negative electrode active material, when a mixture of a chain carbonate and a cyclic carbonate is used, the discharge characteristics, cycle durability, and charge / discharge efficiency can be sometimes improved. Solutes include ClO ₄ ⁻ , CF ₃ S
O ₃ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ C
It is preferable to use a lithium salt having an anion such as O ₂ ⁻ or (CF ₃ SO ₂ ) ₂ N ⁻ .

Further, a vinylidene fluoride / hexafluoropropylene copolymer (for example, Kynar (trade name) manufactured by Atochem Co., Ltd.) may be used as a solvent for the electrolytic solution.
A gelled polymer electrolyte is prepared by adding the vinylidene fluoride / perfluoro (propyl vinyl ether) copolymer disclosed in No. 31 and adding the above solute,
A polymer electrolyte may be used instead of the electrolytic solution.

The above-mentioned electrolytic solution or polymer electrolyte preferably contains a lithium salt in an amount of 0.2 to 2.0 mol / L. Outside this range, the ionic conductivity decreases and the electrical conductivity decreases. More preferably 0.5 to
1.5 mol / L.

The negative electrode active material in the present invention is a material capable of inserting and extracting lithium ions. The negative electrode active material is not particularly limited, for example, lithium metal, lithium alloy,
Examples thereof include carbon materials, oxides mainly composed of metals belonging to Groups 14 and 15 of the periodic table, silicon carbide, silicon oxide, titanium sulfide, and boron carbide. As the carbon material, those obtained by thermally decomposing organic substances under various pyrolysis conditions and artificial graphite, natural graphite, soil graphite, expanded graphite, flaky graphite, and the like can be used, and the oxide is mainly tin oxide. Compounds can be used.
Further, as the negative electrode current collector, a copper foil, a nickel foil, or the like is used.

The negative electrode in the present invention is preferably composed of a negative electrode active material and a binder. An organic solvent is added to a mixture of the negative electrode active material and the binder to form a slurry, and the slurry is applied to a metal foil current collector. It is preferable to obtain by drying, pressing. As the separator interposed between the positive electrode and the negative electrode, a porous polyethylene, a porous polypropylene film, or the like is preferably used. Further, the shape of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited. A sheet shape (a so-called film shape), a folded shape, a rolled bottomed cylindrical shape, a button shape, and the like are selected according to the application.

[0030]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 100 g of potassium hydroxide and 1.6 g of lithium hydroxide monohydrate were placed in a bottomed cylindrical container made of PTFE.
And 140 g of pure water were stirred and dissolved, and then 0.21 g of 100 μm-thick aluminum foil was charged and dissolved. Subsequently, 1.4 g of manganese oxide (Mn ₂ O ₃ ) powder was added, and the mixture was further stirred. Next, the cylindrical container containing the solution was placed in a stainless steel autoclave, and the inside of the autoclave was replaced with nitrogen gas, and then subjected to hydrothermal treatment at 225 ° C. for 10 hours in a closed system. After completion of the reaction, the autoclave was cooled, the slurry-like content was taken out and filtered, and the filter cake was washed with ethanol to remove lithium hydroxide, potassium hydroxide, and the like, and dried to obtain a positive electrode active material powder. .

As a result of X-ray diffraction analysis of the powder by CuKα ray, 2θ = 18 °, 37 °, 39 °, 45 °, 62 °
Diffraction peaks were observed at 65, 67 and 67 degrees, indicating that the powder had a monoclinic phase layered rock-salt LiMnO ₂ structure. At 2θ = 15 °, a diffraction peak based on the LiMnO ₂ structure of a trace amount of orthorhombic phase was observed.
Further, by elemental analysis of the powder, LiMn _0.75 Al _0.25 O
It turned out to be ₂ .

The above-mentioned LiMn _0.75 Al _0.25 O ₂ powder, acetylene black and PTFE powder are mixed in a weight ratio of 80: 16: 4, kneaded while adding toluene, formed into a sheet, and dried. A positive electrode having a thickness of 150 μm was prepared, and an aluminum foil having a thickness of 20 μm was used as a positive electrode current collector. A 25 μm thick porous polyethylene was used for the separator. Further, a metal lithium foil having a thickness of 500 μm was used as a negative electrode, and a nickel foil was used as a negative electrode current collector. In the electrolyte, 1 mol / L LiPF was mixed in a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1.
A solution in which ₆ was dissolved was used.

In an argon glove box, the above-mentioned positive electrode and the above-mentioned negative electrode were opposed to each other with a separator interposed therebetween, and contained in a simple cell made of stainless steel together with the electrolytic solution and sealed to obtain a non-aqueous electrolytic solution secondary battery. ^{3. At} a constant current of 0.2 mA / cm ² .
After charging to 3 V, the battery was discharged to 2.0 V to determine the initial discharge capacity. Further, the charge / discharge cycle was repeated 50 times at a constant current of 0.2 mA / cm ² . The initial discharge capacity at 2.0 to 4.3 V was 160 mAh / g, and the capacity after 50 charge / discharge cycles was 152 mAh / g.

Example 2 Positive electrode active material powder as in Example 1 except that 71 g of sodium hydroxide was used instead of 100 g of potassium hydroxide and 0.36 g of aluminum hydroxide was used instead of 0.21 g of aluminum foil. Was synthesized. X-ray diffraction analysis was carried out in the same manner as in Example 1. As a result, it was found that the sample had a monoclinic layered rock-salt type LiMnO ₂ structure,
A diffraction peak based on the LiMnO ₂ structure composed of a very small amount of orthorhombic crystals was observed. In addition, LiMn was analyzed by elemental analysis.
It turned out to be _0.85 Al _0.15 O ₂ .

A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the above-mentioned positive electrode active material was used, and evaluated in the same manner as in Example 1. The initial discharge capacity was 156 mAh / g.
The capacity after 50 charge / discharge cycles was 140 mAh / g.

Example 3 Using a 1 L PTFE bottomed cylindrical container, manganese nitrate and aluminum nitrate were mixed at a ratio of 3: 1.
An aqueous ammonium hydroxide solution was added to the aqueous solution containing the same molar ratio to cause coprecipitation, and the mixture was heated and dried at 150 ° C.
10 g of aluminum coprecipitated hydroxide (atomic ratio of manganese to aluminum was 3: 1) was obtained.

Manganese oxide powder and aluminum foil glue
In addition, the manganese-aluminum coprecipitated hydroxide powder
Synthesized in the same manner as in Example 1 except that 1.4 g was charged.
A pole active material powder was obtained. X-ray diffraction analysis was performed as in Example 1.
As a result, the monoclinic layered rock salt type LiMnO_TwoWith structure
And a small amount of orthorhombic LiMn at 2θ = 15 °
O_TwoA diffraction peak based on the structure was observed. Also element
Analysis shows that LiMn_0.75Al _0.25O_TwoYou know that
Was.

A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the above-mentioned positive electrode active material was used, and evaluated in the same manner as in Example 1. The initial discharge capacity was 157 mAh / g.
The capacity after 50 charge / discharge cycles was 150 mAh / g.

Example 4 Manganese was prepared in the same manner as in Example 3 except that cobalt nitrate was used instead of aluminum nitrate.
Cobalt coprecipitated hydroxide (atomic ratio of manganese to cobalt was 3: 1) was obtained, and a positive electrode active material powder was synthesized as in Example 3. X-ray diffraction analysis was carried out in the same manner as in Example 1. As a result, it was found that the sample had a monoclinic layered rock-salt type LiMnO ₂ structure,
A diffraction peak based on the LiMnO ₂ structure composed of a very small amount of orthorhombic crystals was observed. In addition, LiMn was analyzed by elemental analysis.
It was found to be _0.75 Co _0.25 O ₂ .

A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the above-mentioned positive electrode active material was used, and evaluated in the same manner as in Example 1. The initial discharge capacity was 152 mAh / g.
The capacity after 50 charge / discharge cycles was 135 mAh / g.

Example 5 Manganese was prepared in the same manner as in Example 3 except that nickel nitrate was used instead of aluminum nitrate.
A nickel coprecipitated hydroxide (atomic ratio of manganese to nickel was 3: 1) was obtained, and a positive electrode active material powder was synthesized as in Example 3. X-ray diffraction analysis was carried out in the same manner as in Example 1. As a result, it was found that the sample had a monoclinic layered rock-salt type LiMnO ₂ structure,
A diffraction peak based on the LiMnO ₂ structure composed of a very small amount of orthorhombic crystals was observed. In addition, LiMn was analyzed by elemental analysis.
It was found to be _0.75 Ni _0.25 O ₂ .

A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the above-mentioned positive electrode active material was used, and evaluated in the same manner as in Example 1. The initial discharge capacity was 158 mAh / g.
The capacity after 50 charge / discharge cycles was 137 mAh / g.

Example 6 A manganese-iron coprecipitated hydroxide (atomic ratio of manganese to iron was 3: 1) was obtained in the same manner as in Example 3 except that iron nitrate was used instead of aluminum nitrate. A positive electrode active material powder was synthesized in the same manner as described above. X as in Example 1
X-ray diffraction analysis showed that monoclinic layered rock salt LiM
A diffraction peak based on a LiMnO ₂ structure having a nO ₂ structure and a small amount of orthorhombic crystals was observed at 2θ = 15 °. In addition, elemental analysis revealed that it was LiMn _0.75 Fe _0.25 O ₂ .

A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the above-mentioned positive electrode active material was used, and evaluated in the same manner as in Example 1. The initial discharge capacity was 155 mAh / g.
The capacity after 50 charge / discharge cycles was 130 mAh / g.

Example 7 A manganese-chromium coprecipitated hydroxide (atomic ratio of manganese to chromium: 3: 3) except that chromium nitrate was used in place of aluminum nitrate.
1) was obtained, and a positive electrode active material powder was synthesized in the same manner as in Example 3.
X-ray diffraction analysis was carried out in the same manner as in Example 1. As a result, a diffraction peak based on the LiMnO ₂ structure having a monoclinic layered rock-salt type LiMnO ₂ structure and a small amount of orthorhombic crystals at 2θ = 15 ° was recognized Was done. In addition, LiMn _0.75
It was found to be Cr _0.25 O ₂ .

A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the above-mentioned positive electrode active material was used, and evaluated in the same manner as in Example 1. The initial discharge capacity was 157 mAh / g.
The capacity after 50 charge / discharge cycles was 135 mAh / g.

Example 8 Manganese-cobalt coprecipitated hydroxide (atomic ratio of manganese to cobalt was 17: 3) in the same manner as in Example 4, except that the molar ratio of manganese nitrate to cobalt nitrate was 17: 3. After obtaining the coprecipitated hydroxide,
The mixed oxide was fired at 50 ° C., and a positive electrode active material powder was synthesized in the same manner as in Example 3 using this mixed oxide. Example 1
An X-ray diffraction analysis was performed in the same manner as described above. As a result, a diffraction peak based on the LiMnO ₂ structure having a monoclinic layered rock salt type LiMnO ₂ structure and a small amount of orthorhombic crystals was observed at 2θ = 15 °. . In addition, LiMn _0.85 Co
It was found to be _0.15 O _2.

A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the above-mentioned positive electrode active material was used, and evaluated in the same manner as in Example 1. The initial discharge capacity was 159 mAh / g.
The capacity after 50 charge / discharge cycles was 140 mAh / g.

Example 9 (Comparative Example) A positive electrode active material powder was synthesized in the same manner as in Example 3 except that aluminum nitrate was not added. When X-ray diffraction analysis was performed in the same manner as in Example 1,
It has a monoclinic layered rock salt type LiMnO ₂ structure, and has a 2θ
A diffraction peak based on a LiMnO ₂ structure composed of a trace amount of orthorhombic crystals was observed at 15 °. In addition, L
It was found to be iMnO ₂ .

A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the above-mentioned positive electrode active material was used, and evaluated in the same manner as in Example 1. The initial discharge capacity was 150 mAh / g.
The capacity after 50 charge / discharge cycles was 90 mAh / g.

[0052]

The non-aqueous electrolyte secondary battery having the positive electrode active material of the present invention can be used in a wide voltage range, has a large capacity,
Excellent charge / discharge cycle durability. Further, since the positive electrode active material of the present invention uses inexpensive manganese instead of conventionally used cobalt and nickel, it can be obtained at low cost.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 4/02 H01M 4/02 C 10/40 10/40 Z F term (Reference) 4G002 AA06 AA10 AB02 AE05 4G048 AA03 AA04 AB02 AC06 AD06 AE05 5H003 AA02 AA04 BA00 BA01 BB05 BB11 BB14 BC01 BD00 BD01 5H014 AA02 BB00 BB01 EE10 HH08 5H029 AJ03 AJ05 AK03 AL06 AL12 AM03 AM04 AM05 AM07 CJ01 CJ02 CJ28 HJ

Claims (7)

[Claims] 1. A has a monoclinic layered rock-salt structure, Li _x Mn _y
M _1-y O ₂ (where M is Al, Fe, C
At least one element selected from the group consisting of o, Ni and Cr, where 0 <x ≦ 1.1 and 0.5 ≦ y <1. )
A positive electrode active material for a non-aqueous electrolyte secondary battery, comprising: 2. In a strongly basic aqueous solution containing a lithium element, a manganese compound and a compound containing the element M are mixed with 13
The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein a hydrothermal treatment is performed at 0 to 300 ° C. 3. The strongly basic aqueous solution after the manganese compound and the compound containing the element M are coprecipitated to form a hydroxide, oxide or oxyhydroxide.
3. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to item 1. 4. The method for producing a positive electrode active material for a nonaqueous electrolyte secondary battery according to claim 2, wherein the manganese compound is added to the strongly basic aqueous solution after dissolving the compound containing the element M. . 5. The method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 2, wherein lithium hydroxide is dissolved in the strong basic aqueous solution. 6. The strong basic aqueous solution in which potassium hydroxide or sodium hydroxide is dissolved.
Or the method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery according to 5 above. 7. A non-aqueous electrolyte secondary battery comprising a positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, a conductive material, and a binder as a positive electrode. Next battery.