JP2001023640A - Lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the use in a broad voltage range, to enhance battery capacity under a high current density and to improve charge/discharge cycle durability by including a lithium transition metal composite oxide having a specific composition as a main component in a positive electrode active material. SOLUTION: A lithium transition metal composite oxide has a lamellar rock salt monoclinic structure and contains a composite oxide expressed by the formula LixMnyM1-yO2, a composite oxide expressed by the formula LixCo1-h-iNihQiO2 and one or more kinds of components selected from a composite oxide expressed by the formula LixCo1-jQjO2, where Q and (x) are independently selected among each of the formulas; M is one or more kinds of elements selected from Al, Fe, Co, Ni and Cr; Q is one or more kinds of elements selected from Al, Fe, Mn, Ti, Ca And Mg; 0<x<=q1.1; 0.5<=y<=1; 0.6<=h<=1.0; 0<=i<=0.10; 0<=1-h-i; and 0<=j<=0.05.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel lithium secondary battery and a positive electrode active material mainly composed of a lithium transition metal composite oxide used therein.

[0002]

2. Description of the Related Art In recent years, with the progress of portable and cordless devices, expectations for a lithium secondary battery which is small, lightweight and has a high energy density are increasing.
LiCoO ₂ , a positive electrode active material for a lithium secondary battery,
Composite oxides of lithium and a transition metal such as LiNiO ₂ , LiMn ₂ O ₄ , and LiMnO ₂ are known. Among them, recently, especially as a highly safe and inexpensive material,
Research on complex oxides of lithium and manganese is active.
The development of a high-voltage, high-energy-density lithium secondary battery using these as a positive electrode active material and a carbon material or the like capable of occluding and releasing lithium as a negative electrode active material is being promoted.

In general, a positive electrode active material used in a lithium secondary battery is a composite oxide in which a transition metal such as cobalt, nickel, and manganese is dissolved in lithium as a main active material. Electrode characteristics such as battery capacity, reversibility, operating voltage, and safety vary depending on the type of transition metal used.

For example, LiCoO ₂ , LiNi _0.8 Co
Lithium secondary batteries using a rock-salt layered composite oxide in which cobalt or nickel is dissolved in lithium, such as _0.2 O ₂ , as a positive electrode active material are relatively 140 to 160 mAh / g and 190 to 210 mAh / g, respectively. A high battery capacity can be achieved, and good reversibility is exhibited in a high voltage range of 2.5 to 4.3 V. However, during charging, there is a problem that the battery easily generates heat at a high temperature due to a reaction between the positive electrode active material and the electrolyte solution solvent. There are also problems such as high cost due to the high cost of cobalt or nickel as a raw material, and low battery capacity in a voltage range of 2.5 to 3.5 V.

On the other hand, a lithium secondary battery using a spinel-type composite oxide made of LiMn ₂ O _{4 made of} relatively inexpensive manganese as a positive electrode active material has a problem in that the positive electrode active material and the electrolyte solvent during charging are mixed. Although the heat generation due to the reaction is relatively difficult, the battery capacity is as low as 100 to 120 mAh / g as compared with the above-mentioned cobalt-based and nickel-based active materials. In addition, the charge / discharge cycle durability is poor, and deterioration occurs rapidly in a low voltage region of less than 3V.

Further, a lithium secondary battery using a spinel-type composite oxide made of LiMn ₂ O ₄ as a positive electrode active material,
Battery capacity in a voltage range of 3.0 to 3.5 V is low. Similarly, a lithium secondary battery using a composite oxide made of orthorhombic LiMnO ₂ having a β-NaMnO ₂ type structure using inexpensive manganese as a raw material is about 2 V lower than LiMn ₂ O _4. Since it can operate up to the voltage range, a high battery capacity can be expected, but the charge / discharge durability is poor.

[0007] As the LiMnO _2, beta-NaMnO the orthorhombic LiMnO ₂ consisting of ₂ -type structure, alpha-NaMnO monoclinic LiMnO ₂ of layered rock-salt structure consisting of ₂ type structure are known. Either LiMnO ₂ is relatively unlikely to generate heat due to the reaction between the positive electrode active material and the electrolyte solution solvent during charging. However, orthorhombic LiMnO ₂ gradually transitions to another crystal phase (spinel phase) due to repetition of charge / discharge, and therefore has poor charge / discharge cycle durability.

[0008] On the other hand, Fe to LiMnO _2, Ni, Co,
Japanese Patent Application Laid-Open No. 10-1
No. 34812. However, LiMnMO ₂ disclosed in the publication has an X-ray diffraction result of JC
As can be seen from the similarity to PDS 35-749, all of them had an orthorhombic LiMnO ₂ structure and had insufficient charge / discharge cycle durability.

LiMnO ₂ having a layered rock salt type monoclinic structure is
It is synthesized by subjecting α-NaMnO ₂ synthesized by an ordinary solid-phase reaction method to ion exchange at a temperature of 300 ° C. or lower in a non-aqueous solvent containing Li ions (ARArmstrong).
and PGBruce, NATURE, Vol.381, P499, 1996). Also,
It has been found that manganese oxides are directly synthesized by hydrothermal treatment in a lithium salt aqueous solution in the presence of an alkali metal hydroxide (Tabuchi et al., JP-A-11-2112).
No. 8). The layered rock salt type monoclinic LiMnO ₂ synthesized by such a method is preferable because it can be industrially manufactured more easily than the ion exchange method.

However, when the layered rock salt type monoclinic LiMnO ₂ produced by the hydrothermal synthesis method is used as the positive electrode active material, the charge / discharge cycle durability is improved as compared with the orthorhombic LiMnO _2, but the LiCoO ₂ is used. ₂ , LiNi _0.8 Co
There is a problem that the charge / discharge cycle durability is still inferior to that of a lithium secondary battery using a rock salt layered composite oxide obtained by dissolving cobalt or nickel in lithium, such as _0.2 O ₂ , as a positive electrode active material. If further using a layered rock-salt monoclinic LiMnO ₂ as a positive electrode active _{material, LiCoO 2, LiNi 0.8 Co 0} .2
There is also a problem that the battery capacity development at a large current density is inferior to that of a lithium secondary battery using a layered rock salt type composite oxide in which cobalt or nickel is dissolved as in O ₂ as a positive electrode active material.

Instead of using these single lithium transition metal composite oxides as the positive electrode active material, an orthorhombic L
LiMnO ₂ , LiNiO ₂ , LiCoO ₂ and LiM
Japanese Patent Laid-Open No. 9-1 discloses a method of mixing at least one lithium transition metal composite oxide selected from the group consisting of n ₂ O _4.
No. 80718 is proposed. However, a battery using such a mixture has a problem of insufficient charge / discharge cycle durability. Japanese Patent Application Laid-Open No. 11-3698 discloses Li
A lithium secondary battery comprising a mixture of three kinds of Mn ₂ O ₄ , LiNiO ₂ and LiCoO ₂ has been proposed. Such L
A battery using a mixture of three kinds of iMn ₂ O ₄ , LiNiO ₂ and LiCoO ₂ has a low discharge capacity of LiMn ₂ O ₄ per unit weight in a charge-discharge voltage range of 4.3 to 3.0 V. Low discharge capacity. In addition, 4.3-2.
When charging / discharging is performed in the voltage range of 5 V, the battery capacity is rapidly reduced due to the deterioration of LiMn ₂ O _{4 as} the charge / discharge cycle progresses.

[0012]

The present invention enables use in a wide voltage range, has a high battery capacity under a high current density, has excellent charge / discharge cycle durability, high safety, a high energy density and An object of the present invention is to provide a lithium secondary battery having good large-current discharge characteristics and a positive electrode active material used for the same.

[0013]

According to the present invention, there is provided a lithium secondary battery provided with a positive electrode active material layer comprising a lithium transition metal composite oxide as a main component, wherein the lithium transition metal composite oxide comprises the following component (B): And at least one component selected from the following component (C) and the following component (A). (A) having a layered rock-salt monoclinic _{structure, Li x Mn y M 1-} y
Composite oxide represented by O ₂ (B) A composite oxide represented by Li _x Co _1-hi Ni _h Q _i O ₂ . (C) A composite oxide represented by Li _x Co _1-j Q _j O ₂ .

However, the symbols in the formula have the following meanings. Between each formula, Q and x are independently selected. M: Al, F
e, one or more elements selected from Co, Ni and Cr,
Q: One or more elements selected from Al, Fe, Mn, Ti, Ca and Mg.

0 <x ≦ 1.1, 0.5 ≦ y ≦ 1,
0.6 ≦ h ≦ 1.0, 0 ≦ i ≦ 0.10, 0 ≦ 1-h
−i, 0 ≦ j ≦ 0.05.

Hereinafter, the present invention will be described in more detail.

[0017]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, is a component of the lithium-transition metal composite oxide _{(A), Li x Mn y} M 1-y O 2
The compound oxide represented by the formula has a crystal structure with a layered rock salt type monoclinic structure.However, compared to the orthorhombic structure, the composite oxide has a higher charge / discharge cycle durability. Was found.

As the metal element M in the composite oxide of the component (A), one or more elements selected from Al, Fe, Co, Ni and Cr are used. Among them, Fe and Cr are preferable because of excellent charge / discharge cycle durability. In the above formula representing the composite oxide of the component (A),
x is 0 <x ≦ 1.1, and y is 1. When y is less than 0.5, the layered rock salt monoclinic structure cannot be maintained. Particularly preferably, y is 0.65 ≦ y ≦ 0.99
Is adopted.

In the present invention, the content of the component (A) in the lithium transition metal composite oxide is preferably 30 to 80% by weight. If the content is less than 30% by weight, the safety of the lithium battery is poor, and the battery capacity in a voltage range of less than 3 V is reduced. On the other hand, if it exceeds 80% by weight, the discharge capacity at a large current is reduced, so that it is inappropriate. A particularly preferred content of the component (A) is 40 to 70% by weight.

[0020] In the present invention, the composite oxide of the component (B) is represented by _{Li x Co 1-hi Ni h} Q i O 2, Q is
It is one or more elements selected from Al, Fe, Mn, Ca, and Mg. The presence of Q improves charge / discharge cycles, durability, or battery safety. Above all, Q
Is preferably Mn or Al.

In the formula of the component (B), x is 0 <x ≦
1.1 and h is 0.6 ≦ h ≦ 1.0. The atomic ratio of nickel to cobalt in component (B) is the above h
It is preferable to adjust 70 and i so that 70:30 to 85:15. If the amount of cobalt is larger than this ratio, the capacity is undesirably reduced. If the amount of cobalt is less than this ratio, the charge / discharge cycle durability becomes poor, which is not preferable. The atomic ratio of nickel to cobalt is 8
It is particularly preferred that the ratio be from 0:20 to 84:16.

In the above formula of the component (B), i is 0 ≦
i ≦ 0.10, and the charge / discharge cycle, durability, and battery safety are improved. In particular, i preferably satisfies 0.001 ≦ i ≦ 0.05 so as to form a solid solution of about 0.1 to 5% with respect to the total amount of nickel and cobalt.

In the present invention, the composite oxide of the component (C) is represented by Li _x Co _1-j Q _j O ₂ , where Q is Al,
It is one or more elements selected from Fe, Mn, Ca and Mg, and is independently selected from Q of the component (B). Q
, The charge / discharge cycle, durability, and battery safety are improved. Among them, Q is preferably Ti or Ca.

In the above formula of the component (C), x is 0 <
x ≦ 1.1, and j is 0 ≦ j ≦ 0.05. In particular, j is 0.001 ≦ j ≦ such that Q forms a solid solution of about 0.1 to 3% in atomic ratio with respect to the total amount of cobalt and Q.
It is preferably 0.03.

In the present invention, the content of the component (B) in the lithium transition metal composite oxide is preferably from 20 to 70% by weight. If the content is less than 20% by weight, the capacity of the lithium secondary battery is reduced, and the large current charge / discharge characteristics are undesirably reduced. The content of the component (B) is from 30 to 60.
It is particularly preferred that the amount is by weight. The content of the component (C) in the lithium transition metal composite oxide is preferably from 20 to 70% by weight. If the content is less than 20% by weight, the capacity of the lithium secondary battery is reduced, and the large current charge / discharge characteristics are undesirably reduced. The content of the component (C) is 3
It is particularly preferred that the content is 0 to 60% by weight or more. And
When the component (B) and the component (C) are contained in the lithium transition metal composite oxide, the total content of both components is
Preferably, it is suitably from 20 to 70% by weight, especially from 30 to 60% by weight.

In the present invention, preferable representative examples of the lithium secondary battery include the following (1) and (2). The component (A), the component (B) and the component (C) used in the present invention are each one or more of the corresponding composite oxides.

(1) In a lithium secondary battery provided with a positive electrode active material layer mainly composed of a lithium transition metal composite oxide, the lithium transition metal composite oxide contains 30 to 80% by weight.
A secondary battery comprising a mixture of the component (A) of the formula (I) and 20 to 70% by weight of the component (B). Among them, the component (B), in _{Li x Co 1-hi Ni h} Q i O 2, 0.
7 ≦ h ≦ 0.9, 0 ≦ i ≦ 0.10, especially 0.75
A lithium secondary battery satisfying ≦ h ≦ 0.85 and 0.001 ≦ i ≦ 0.05.

(2) In a lithium secondary battery provided with a positive electrode active material layer containing a lithium transition metal composite oxide as a main component, 30 to 80% by weight of the following component (A) and 20 to 70% by weight:
A lithium secondary battery containing a mixture with the following component (C) by weight.

In the present invention, the positive electrode using the positive electrode active material containing the lithium transition metal composite oxide as a main component is as follows:
Preferably, it is manufactured as follows. That is, a positive electrode mixture is formed by mixing a powder of the composite oxide mixture with a carbon-based conductive material such as acetylene black, graphite, and Ketjen black, a binder, and a solvent or a dispersion medium of the binder. .

The above-mentioned positive electrode mixture is formed into a slurry or a kneaded material, which is applied or carried on a positive electrode current collector such as an aluminum foil or a stainless steel foil, and is press-rolled to form a positive electrode active material layer on the positive electrode current collector. . As the binder, polyvinylidene fluoride, polytetrafluoroethylene, polyamide, carboxymethyl cellulose, acrylic resin, or the like is used.

In the present invention, the porosity of the positive electrode active material layer is preferably from 27 to 37%. If the porosity is less than 27%, it becomes difficult to impregnate the electrolytic solution, and the internal resistance of the battery increases, which is not preferable. If it exceeds 37%, the volume of the positive electrode active material layer increases, and the charge / discharge capacity per unit volume decreases, which is not preferable. The porosity is particularly preferably 30 to 35%. The porosity of the positive electrode active material layer is determined by pressing conditions when press rolling the positive electrode body in which the positive electrode active material layer is formed on the positive electrode current collector, or the content of a solvent or a dispersion medium when forming a slurry or a kneaded material. Is controlled by In the present invention, the porosity of the positive electrode was determined from the apparent density and the true density.

The composite oxide of component (A) used in the present invention is synthesized from a compound containing a manganese compound, a lithium compound and a metal element M by a known method such as baking at 500 to 1000 ° C. by a solid phase method. Among them, a manganese compound and a compound containing a metal element M in an aqueous solution containing a lithium element and an alkali metal hydroxide other than the lithium element, preferably, are produced by hydrothermal treatment at 130 to 300 ° C. It is appropriate.

Among the above hydrothermal treatment methods, a compound containing a manganese compound and a metal element M in a strongly basic aqueous solution containing a high concentration of potassium hydroxide or sodium hydroxide in addition to the lithium element, manganese and a metal element, M It is particularly preferable to manufacture by subjecting at least one of the coprecipitated hydroxide, coprecipitated oxide and coprecipitated oxyhydroxide to a hydrothermal treatment at 130 to 300 ° C.

As the manganese raw material in the above, Mn is used.
Examples thereof include oxides such as ₂ O ₃ , MnO, and MnO ₂ , hydrates of these oxides, and oxyhydroxides. As the manganese raw material, a trivalent manganese compound is more preferable.
These manganese raw materials may be used alone or in combination of two or more.

As the raw material compound of the metal element M,
Simple metals, hydroxides, oxides, oxyhydroxides, chlorides, nitrates and the like are used. These raw materials may be used alone or in combination of two or more.

In the lithium secondary battery of the present invention, the solvent for the electrolyte solution is preferably a carbonate ester. Carbonate can be used either cyclic or chain. Examples of the cyclic carbonate include propylene carbonate and ethylene carbonate (hereinafter referred to as EC). Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate (hereinafter referred to as DEC), ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate and the like.

In the present invention, the above-mentioned carbonates can be used alone or in combination of two or more, and may be used by mixing with other solvents. Further, depending on the material of the negative electrode active material, the combined use of a chain carbonate and a cyclic carbonate may improve the discharge characteristics, cycle durability, and charge / discharge efficiency.

In the present invention, a vinylidene fluoride-hexafluoropropylene copolymer (for example, Kynar: trade name of Atochem Co.) may be used as the organic solvent.
No. 4131, vinylidene fluoride-perfluoro (propyl vinyl ether) copolymer was added,
Gel polymer electrolytes can also be used by adding the following solutes:

The solutes constituting the electrolyte solution according to the present invention include ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ ,
AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ CO ₂ ⁻ , (CF ₃ SO ₂ ) ₂ N
^- it is preferable to use any one or more of lithium salt having an anion the like. In the above-mentioned electrolyte solution or polymer electrolyte, it is preferable that an electrolyte composed of a lithium salt is added to the solvent or the solvent-containing polymer at a concentration of 0.2 to 2.0 mol / L. Outside this range, the ionic conductivity decreases, and the electrical conductivity of the electrolyte solution or polymer electrolyte decreases. More preferably 0.5 to
1.5 mol / l is selected. For the separator, a porous polyethylene or a porous polypropylene film is preferably used.

The negative electrode active material used in the present invention is a material capable of inserting and extracting lithium ions. The material forming these negative electrode active materials is not particularly limited, but lithium metal, a lithium alloy, a carbon material, an oxide mainly containing a metal of Group 14, 15 of the periodic table, a carbon compound, a silicon carbide compound, a silicon oxide compound, Examples include titanium sulfide and boron carbide compounds. As the carbon material, those obtained by thermally decomposing organic substances under various thermal decomposition conditions, artificial graphite, natural graphite, earth graphite, expanded graphite, flaky graphite and the like can be used. As the oxide, a compound mainly composed of tin oxide can be used. As the negative electrode current collector, a copper foil, a nickel foil, or the like is used.

When the active material is a carbon material, the negative electrode used in the present invention is obtained by kneading with an organic solvent to form a slurry, applying the slurry to a metal foil current collector, drying and pressing. Is preferred. The shape of the lithium 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.

[0042]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. Examples 11 to 14 are comparative examples.

Example 1 An aqueous solution of ammonium hydroxide was added to a mixed aqueous solution of manganese nitrate and aluminum nitrate (molar ratio: 0.85: 0.15) to cause coprecipitation, and then heated and dried at 150 ° C. to form a manganese-aluminum coprecipitated water. An oxide (manganese: aluminum atomic ratio = 0.85: 0.15) was obtained.

A manganese-aluminum coprecipitated hydroxide powder was added to an aqueous alkali solution containing 41% by weight of potassium hydroxide and 0.45% by weight of lithium hydroxide, followed by stirring. After the inside of the autoclave was replaced with nitrogen gas, 10 g at 225 ° C.
Hydrothermal treatment for hours. After the reaction was completed, the autoclave was cooled and then the contents were taken out. The contents slurry was filtered, washed with ethanol to remove lithium hydroxide, potassium hydroxide and the like, and dried to obtain a powder.

As a result of X-ray diffraction analysis of the powder by CuKα, 2θ was 18 °, 37 °, 39 °, 45 °, 62 °,
Diffraction peaks were observed at 65 ° and 67 °, indicating that these were LiMnO ₂ having a layered rock salt type monoclinic structure. Elemental analysis of the powder indicated LiMn _0.85 Al _0.15 O ₂
It turned out to be.

On the other hand, the molar ratio of nickel and cobalt is
82:18 with NiCl _Two・ 6H_TwoO and CoC
l_Two ・ 6H_TwoO and dissolved in pure water saturated with carbon dioxide
NaHCO_ThreeAn aqueous solution was added and the resulting precipitate
After washing the residue in water and drying at 140 ° C in nitrogen gas,
Nickel-cobalt (82:18 atomic ratio) coprecipitated carbonate
I got This carbonate is mixed with lithium carbonate at 910 ° C
LiNi is fired for 5 hours._0.82Co_0.18O_TwoTo
Obtained.

The LiMn _0.85 Al _0.15 O obtained above was obtained.
₂ and LiNi _0.82 Co _0.18 O ₂ are mixed at a weight ratio of 50:50, and this mixed powder, acetylene black and polyvinylidene fluoride are mixed at a weight ratio of 83/10/7 in N 2.
-Ball mill mixing with addition of methylpyrrolidone to form a slurry. This slurry was applied on a 20 μm-thick aluminum foil positive electrode current collector, and dried at 150 ° C. to remove N-methylpyrrolidone. Thereafter, roll press rolling was performed to obtain a positive electrode body.

A porous polypropylene having a thickness of 25 μm was used for the separator, a metal lithium foil having a thickness of 500 μm was used for the negative electrode, a nickel foil was used for the negative electrode current collector, and 1 M LiPF ₆ / EC + DEC (for the electrolyte) was used. 1: 1), a simple closed cell made of stainless steel (hereinafter referred to as a battery) was assembled in an argon glove box. In addition, 1M Li
PF ₆ / EC + DEC (1: 1) means an electrolyte solution containing 1 M LiPF ₆ as a solute in a solvent containing EC and DEC at a volume ratio of 1: 1.

1 mA per 1 cm ² of positive electrode area of the above battery
At a current density of 4.3 V and a constant current of 2 mA / cm
^The battery was discharged to 2.0 V at ² , and a charge / discharge cycle test was performed 20 times at a high current density and a wide voltage range. I asked.

For battery safety evaluation, the cell after 4.3 V charge was disassembled, and the positive electrode was placed in a closed container together with an electrolyte solvent to form a sample, and the temperature was raised using a differential scanning calorimeter. The exothermic onset temperature at that time was determined. Table 1 shows the results.

Example 2 A manganese-cobalt coprecipitated hydroxide was synthesized in the same manner as in Example 1 except that cobalt nitrate was used instead of aluminum nitrate, and then a lithium-manganese-cobalt composite oxide was synthesized as in Example 1. did. X-ray diffraction analysis revealed that the produced powder was LiMnO ₂ having a layered rock salt type monoclinic structure as in Example 1. Elemental analysis of the powder indicated LiMn _0.85 Co _0.15 O ₂ .

In Example 1, LiMn_0.85Al_0.15O_Two
Instead of LiMn_0.85Co_0.15O_Two Using LiNi
_0.82Co_0.18O_TwoAnd 50:50 by weight.
Otherwise, in the same manner as in Example 1, a positive electrode body and a battery were fabricated,
The properties were evaluated. Table 1 shows the results.

Example 3 A manganese-nickel coprecipitated hydroxide was synthesized in the same manner as in Example 1 except that nickel nitrate was used instead of aluminum nitrate.
A lithium-manganese-nickel composite oxide was synthesized.
The powder produced by X-ray diffraction analysis was found to be LiMnO ₂ having a layered rock salt type monoclinic structure as in Example 1. Elemental analysis of the powder revealed LiMn _0.85 Ni _0.15 O ₂
It turned out to be.

In Example 1, LiMn _0.85 Al _0.15 O ₂
Using LiMn _0.85 Ni _0.15 O ₂ instead of LiNi
_A positive electrode body and a battery were prepared in the same manner as in Example 1 except that the mixture was mixed with _0.82 Co _0.18 O ₂ at a weight ratio of 50:50.
The properties were evaluated. Table 1 shows the results.

Example 4 A manganese-iron coprecipitated hydroxide was synthesized in the same manner as in Example 1 except that iron nitrate was used instead of aluminum nitrate, and a lithium-manganese-aluminum composite oxide was synthesized in the same manner as in Example 1. did. The powder produced by X-ray diffraction analysis was found to be LiMnO ₂ having a layered rock salt type monoclinic structure as in Example 1. Elemental analysis of the powder indicated LiMn _0.85 Fe _0.15 O ₂ .

In Example 1, LiMn_0.85Al_0.15O_Two
Instead of LiMn_0.85Fe_0.15O_Two Using LiNi
_0.82Co_0.18O_TwoAnd 50:50 by weight.
Otherwise, in the same manner as in Example 1, a positive electrode body and a battery were fabricated,
The properties were evaluated. Table 1 shows the results.

Example 5 A manganese-chromium coprecipitated hydroxide was synthesized in the same manner as in Example 1 except that chromium nitrate was used instead of aluminum nitrate. According to the X-ray diffraction analysis, the powder produced was a layered rock salt type LiM having a monoclinic crystal as in Example 1.
It turned out that it was an nO ₂ structure. Elemental analysis of the powder indicated LiMn _0.85 Cr _0.15 O ₂ .

In Example 1, LiMn _0.85 Al _0.15 O ₂
LiMn _0.85 Cr _0.15 O ₂ instead of LiNi
_A positive electrode body and a battery were prepared in the same manner as in Example 1 except that the mixture was mixed with _0.82 Co _0.18 O ₂ at a weight ratio of 50:50.
The properties were evaluated. Table 1 shows the results.

Example 6 A manganese hydroxide was synthesized in the same manner as in Example 1 except that aluminum nitrate was not used.
In the same manner as in the above, a lithium-manganese composite oxide was synthesized. X
The powder produced by the line diffraction analysis was found to have a layered rock salt type LiMnO ₂ structure having a monoclinic crystal as in Example 1. Elemental analysis of the powder indicated LiMnO ₂ .

In Example 1, LiMn _0.85 Al _0.15 O ₂
Instead of LiMnO ₂ , LiNi _0.82 Co _0.18
A positive electrode body and a battery were prepared and the characteristics were evaluated in the same manner as in Example 1 except that O ₂ was mixed at a weight ratio of 50:50. Table 1 shows the results.

[0061] [Example 7] and lithium carbonate Li ₂ CO ₃ powder cobalt oxide Co ₃ O ₄ powder were dry mixed, 1 at 900 ° C.
LiCoO ₂ was obtained by firing in the air for 0 hours.

The LiMn _0.85 Al _0.15 O ₂ prepared in Example 1
A positive electrode body and a battery were prepared and the characteristics were evaluated in the same manner as in Example 1 except that the above and LiCoO ₂ were mixed at a weight ratio of 50:50. Table 1 shows the results.

Example 8 LiMn _0.85 Al _0.15 O ₂ and Li
A positive electrode body and a battery were fabricated and characteristics were evaluated in the same manner as in Example 1 except that Ni _0.82 Co _0.18 O ₂ was mixed at a weight ratio of 40:60. Table 1 shows the results.

Example 9 LiMn _0.85 Al _0.15 O ₂ and Li
A positive electrode body and a battery were prepared and the characteristics were evaluated in the same manner as in Example 1 except that Ni _0.82 Co _0.18 O ₂ was mixed at a weight ratio of 60:40. Table 1 shows the results.

Example 10 LiMn _0.85 Al _0.15 O ₂ and L
A positive electrode body and a battery were prepared and the characteristics were evaluated in the same manner as in Example 1, except that iNi _0.82 Co _0.18 O ₂ was mixed at a weight ratio of 75:25. Table 1 shows the results.

Example 11 For comparison, LiNi _0.82 Co
_A positive electrode body and a battery were prepared and the characteristics were evaluated in the same manner as in Example 1, except that only _0.18 O ₂ was used and LiMn _0.85 Al _0.15 O ₂ was not mixed. Table 1 shows the results.

Example 12 For comparison, LiMn _0.85 Al
_A positive electrode body and a battery were prepared and the characteristics were evaluated in the same manner as in Example 1 except that only _0.15 O ₂ was used and LiNi _0.82 Co _0.18 O ₂ was not mixed. Table 1 shows the results.

Example 13 For comparison, a cathode body and a battery were prepared and evaluated in the same manner as in Example 7, except that only LiCoO ₂ was used and LiMn _0.85 Al _0.15 O ₂ was not mixed. Table 1 shows the results.

Example 14 For comparison, a positive electrode body and a battery were prepared and evaluated in the same manner as in Example 6, except that only LiMnO ₂ was used and LiCoO ₂ was not mixed. Table 1 shows the results.

[0070]

[Table 1]

[0071]

According to the present invention, a lithium battery which can be used in a wide voltage range, has a large capacity at a high current density, has a low heat generation temperature, has high safety, and has good charge / discharge cycle durability. A secondary battery and a positive electrode active material therefor can be obtained.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5H003 AA02 AA04 BB05 BC06 BD00 BD04 5H014 AA02 EE10 HH01 HH02 5H029 AJ03 AJ05 AK03 AL02 AL04 AL06 AL12 AM00 AM03 AM05 AM07 AM16 BJ02 BJ03 BJ04 BJ14 BJ15 HJ01 HJ

Claims (7)

[Claims] 1. A lithium secondary battery provided with a positive electrode active material layer containing a lithium transition metal composite oxide as a main component, wherein the lithium transition metal composite oxide is selected from the following component (B) and the following component (C): A lithium secondary battery comprising at least one component and the following component (A). (A) having a layered rock-salt monoclinic _{structure, Li x Mn y M 1-} y
A composite oxide represented by O ₂ . (B) A composite oxide represented by Li _x Co _1-hi Ni _h Q _i O ₂ . (C) A composite oxide represented by Li _x Co _1-j Q _j O ₂ . However, the symbols in the formula have the following meanings. Between each formula, Q and x are independently selected. M: one or more elements selected from Al, Fe, Co, Ni and Cr, Q: Al, Fe,
One or more elements selected from Mn, Ti, Ca and Mg. 0 <x ≦ 1.1, 0.5 ≦ y ≦ 1, 0.6 ≦ h ≦
1.0, 0 ≦ i ≦ 0.10, 0 ≦ 1-hi, 0 ≦
j ≦ 0.05. 2. The lithium transition metal composite oxide according to claim 1, wherein
The lithium secondary battery according to claim 1, comprising 0% by weight of the component (A) and 20 to 70% by weight of the component (B). Wherein component _{(B), Li x Co 1-hi Ni} h Q i O
_3. The lithium secondary battery according to claim 1, which is a composite oxide in which 0.7 ≦ h ≦ 0.9 and 0 ≦ i ≦ 0.05. 4. The method according to claim 1, wherein the lithium transition metal composite oxide is 30 to 8%.
2. The lithium secondary battery according to claim 1, comprising 0% by weight of the component (A) and 20 to 70% by weight of the component (C). 5. The composite oxide of component (A) is prepared by mixing a manganese compound and a compound containing a metal element M at 130 to 300 ° C. in an aqueous solution containing a lithium element and an alkali metal hydroxide other than the lithium element. The lithium secondary battery according to any one of claims 1 to 4, which is manufactured by hydrothermal treatment. 6. A positive electrode comprising a lithium transition metal composite oxide as a main component has a porosity of 27 to 37%.
The lithium secondary battery according to any one of the above. 7. A lithium transition metal composite oxide containing at least one component selected from the following components (B) and (C) and the following component (A): Positive electrode active material for lithium secondary batteries. (A) having a layered rock-salt monoclinic _{structure, Li x Mn y M 1-} y
A composite oxide represented by O ₂ . (B) A composite oxide represented by Li _x Co _1-hi Ni _h Q _i O ₂ . (C) A composite oxide represented by Li _x Co _1-j Q _j O ₂ . However, the symbols in the formula have the following meanings. Between each formula, Q and x are independently selected. M: one or more elements selected from Al, Fe, Co, Ni and Cr, Q: Al, Fe,
One or more elements selected from Mn, Ti, Ca and Mg. 0 <x ≦ 1.1, 0.5 ≦ y ≦ 1, 0.6 ≦ h ≦
1.0, 0 ≦ i ≦ 0.10, 0 ≦ 1-hi, 0 ≦
j ≦ 0.05.