JP2002141067A - Positive electrode material for lithium secondary battery, positive electrode for lithium secondary battery and lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve high temperature characteristics in case of lithium transition metal oxide being used as an active material. SOLUTION: A lithium transition metal complex acid consisting of at least one kind of transition metal selected from a group of Ni, Co, and Mn, and lithium is included together with a condensation polycyclic compound (A) having a diazole ring and a benzene ring as part of rings constituting a condensation polycyclic structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a positive electrode material for a lithium secondary battery, and more particularly to a positive electrode and a lithium secondary battery using the same.

[0002]

2. Description of the Related Art As a positive electrode active material for providing a practically usable lithium secondary battery, a lithium transition metal composite oxide is promising. Among these compounds, when cobalt, nickel, and manganese are used as transition metals, and lithium cobalt composite oxide, lithium nickel composite oxide, and lithium manganese composite oxide are used as the positive electrode active material, high performance battery characteristics can be obtained. it can. For this reason, research and development for practical use of these compounds have been actively conducted, but various problems need to be overcome even if these materials are used, in order to reach the practical use level.

[0003] One of the problems to be solved is characteristic deterioration in a high-temperature environment. Deterioration of the characteristics of a lithium secondary battery in a high-temperature environment is due to the fact that these lithium cobalt composite oxide, lithium nickel composite oxide, and lithium manganese composite oxide used as a positive electrode active material become active and deteriorate themselves. It is considered that various factors such as decomposition of the electrolyte solution, destruction of the film formed on the negative electrode surface, and the like occur.

[0004] In particular, lithium manganese composite oxides such as LiMn ₂ O ₄ have a larger reserve of manganese as a raw material than lithium cobalt composite oxide or lithium nickel composite oxide compared to cobalt or nickel. Although it has many advantages such as low cost and high safety in overcharging, the demand for improving high-temperature characteristics is particularly high because the battery performance (cycle characteristics) in the high-temperature environment is inferior.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to use a lithium transition metal composite oxide containing cobalt, nickel, or manganese as a transition metal. It is an object of the present invention to provide a positive electrode material for a lithium secondary battery and a lithium secondary battery in which high-temperature characteristics such as high-temperature cycle characteristics, which are problems unique to the above, are improved.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and consequently found that a condensed polycyclic ring having a diazole ring and a benzene ring as a part of a ring constituting a condensed polycyclic structure. The present inventors have found that the presence of the compound improves the battery characteristics at high temperatures, and have led to the present invention.

That is, the gist of the present invention is as follows (1) to (1).
5). (1) A lithium transition metal composite oxide of at least one transition metal selected from the group consisting of Ni, Co, and Mn and lithium, and a diazole ring and a benzene ring as a part of a ring constituting a condensed polycyclic structure. And a condensed polycyclic compound (A). (2) The positive electrode material for a lithium secondary battery according to (1), wherein the diazole ring constituting the condensed polycyclic compound (A) is an imidazole ring. (3) The positive electrode material for a lithium secondary battery according to (1) or (2), wherein the condensed polycyclic compound (A) has a benzimidazole skeleton. (4) The compound according to any one of (1) to (3), wherein the condensed polycyclic compound (A) is a compound represented by the following general formula (I) or a tautomer thereof. Positive electrode material for lithium secondary batteries.

[0008]

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(Wherein R _{1 to} R ₅ each independently represent a hydrogen atom, a nitro group, a cyano group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group,
ec-butyl group, tert-butyl group, vinyl group, 1-
Propenyl group, allyl group, 2-propynyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, 1-cyclohexenyl group, phenyl group, tolyl group, Xylyl group, mesityl group, cumenyl group, benzyl group, phenethyl group, α-methylbenzyl group, benzhydryl group, trityl group, styryl group, cinnamyl group, biphenylyl group, naphthyl group, anthryl group, phenanthryl group, 9-fluorenyl group, Fluoro group, chloro group,
Bromo, iodo, iodosyl, iodosyl, dichloroiodo, hydroxy, methoxy, ethoxy, propoxy, isopropoxy, butoxy, phenoxy, benzyloxy, carboxy, methoxycarbonyl, ethoxy Carbonyl, formyloxy, acetoxy, benzoyloxy, formyl, acetyl, propionyl, butyryl, isobutyryl, fluoroformyl, chloroformyl, bromoformyl, iodoformyl, pyroboyl, oxalo , Methoxalyl, ethoxylyl, cyclohexylcarbonyl, benzoyl, toluoyl, cinnamoyl, naphthoyl, acetonyl, phenacyl, salicyl, salicyloyl, anisyl, anisoyl, benzylo Cicarbonyl, mercapto, methylthio, ethylthio, phenylthio, thioformyl, thioacetyl, mercaptocarbonyl, hydroxythiocarbonyl, dithiocarboxy, thiocarbamoyl, sulfino, sulfo, mesyl, benzenesulfonyl Group, tosyl group, sulfamoyl group, sulfoamino group, amino group, ammonium group, methylamino group, dimethylamino group, anilino group, toluidino group, xylidino group, imino group, phenylimino group,
Isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, hydroxyamino group, hydroxyimino group, acetylamino group, benzamide group, succinimide group, phthalimide group, carbamoyl group, nitroso group, acinitro group, hydrazino group, hydrazono group , Hydrazo group, azo group, phenylazo group, naphthylazo group, azoxy group, diazo group, azido group, diazoamino group, ureido group, weylene group, amidino group, guanidide group, picryl group, pyridyl group, piperidino group, piperidyl group, or Represents a quinolyl group. (5) The fused polycyclic compound (A) is benzimidazole,
5-nitrobenzimidazole, 5-cyanobenzimidazole, 5-benzimidazolecarboxylic acid, 4,5
-Dichloro-trifluoromethyl-1H-benzimidazole, 5-acetylbenzimidazole, 5-sulfobenzimidazole, 5-aldehyde benzimidazole, 5-fluorobenzimidazole, 5-chlorobenzimidazole, 5-bromobenzimidazole, 5-
Iodobenzimidazole, 5-methylbenzimidazole, 2-aminobenzimidazole, 2-amino-
5,6-dimethylbenzimidazole, 2- (allylthio) benzimidazole, 2-amino-1-methylbenzimidazole, 2-benzimidazole acetonitrile, methyl 2-benzimidazole carbamate, 2
-Chlorobenzimidazole, 2- (chloromethyl) benzimidazole, 5,6-dimethylbenzimidazole, 2-guanidinobenzimidazole, 2-hydroxybenzimidazole, N ^1- (6-indazolyl) sulfanylamide, 5-methoxybenzimidazole ,
2-methylbenzimidazole, methyl 1- (butylcarbamoyl) -2-benzimidazolecarbamate, 2-methyl-5-nitrobenzimidazole, 2-
(Methylthio) benzimidazole, 2-phenylbenzimidazole, 2-phenyl-5-benzimidazolesulfonic acid, 2- (2-pyridyl) benzimidazole, 2- (trifluoromethyl) benzimidazole,
And the positive electrode material for a lithium secondary battery according to any one of (1) to (4), wherein the positive electrode material is selected from the group consisting of and 2,5,6-trimethylbenzimidazole. (6) The lithium according to any one of (1) to (5), wherein the ratio of the condensed polycyclic compound (A) to the lithium transition metal composite oxide is 0.01 to 20 mol%. Positive electrode material for secondary batteries. (7) The positive electrode material for a lithium secondary battery according to any one of (1) to (6), wherein the lithium transition metal composite oxide is a lithium manganese composite oxide. (8) The lithium secondary battery according to any one of (1) to (7), wherein the lithium manganese composite oxide is a lithium manganese composite oxide in which a part of a manganese site is substituted with another element. Cathode material for battery. (9) Another element that partially replaces the manganese site is A
1, Ti, V, Cr, Fe, Co, Li, Ni, Cu,
The positive electrode material for a lithium secondary battery according to (8), wherein the positive electrode material is at least one metal element selected from the group consisting of Zn, Ga, and Zr. (10) The positive electrode material for a lithium secondary battery according to any one of (1) to (9), wherein the lithium manganese composite oxide has a spinel structure. (11) (1) A positive electrode for a lithium secondary battery, comprising the positive electrode material for a lithium secondary battery according to any one of (1) to (10) and a binder. (12) A lithium secondary battery comprising the positive electrode according to (11), a negative electrode, and an electrolyte layer. (13) The negative electrode contains a carbon material (1).
The lithium secondary battery according to 2). (14) In a lithium secondary battery using a lithium transition metal composite oxide having at least one transition metal selected from the group consisting of Ni, Co, and Mn and lithium as a positive electrode active material, a condensed polycyclic compound (A ). A lithium secondary battery comprising: (15) The lithium secondary battery according to (14), wherein the lithium transition metal composite oxide is a lithium manganese composite oxide.

The details of the reason why the compound (A) exerts the improvement effect are unknown, but the compound effectively suppresses the progress of the degradation reaction mainly occurring at the positive electrode active material-electrolyte interface in a high temperature environment. It is thought that it was done. Also, as a general theory, an additive that exerts an effect on improving certain characteristics, on the other hand, brings about side effects, causes deterioration of other characteristics or adversely affects other battery constituent materials, and is not necessarily considered as a whole battery system. Not always appropriate. On the other hand, it can be said that the compound (A) has no or very little adverse effect.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The properties of the condensed polycyclic compound (A) having a diazole ring and a benzene ring as a part of the ring constituting the condensed polycyclic structure used in the present invention are not particularly limited. In addition, various properties such as powder, liquid and the like can be used, but powder is preferable because it has an advantage that it is particularly easy to handle and has a low production cost when mixed with the positive electrode active material. .

"Fused polycyclic compound (A)" in the present invention
The term “cyclic compound” means a compound having two or more rings and a condensed ring in which each ring shares two or more atoms. The number of rings is not particularly limited, but is preferably a bicyclic ring including a diazole ring. Further, the “diazole ring” means an aromatic 5-membered ring containing two nitrogen atoms, and includes, for example, 1,2-diazole and 1,3-diazole. It is preferable to use 1,3-diazole (imidazole) because of its relatively high thermal stability and high basicity.

In the present invention, it is preferable to use the condensed polycyclic compound (A) having a diazole ring because the diazole ring present in the condensed polycyclic compound (A) exhibits the following functions. Conceivable. That is, (i) the lone electron pair of the 2- or 3-position ring nitrogen atom is 6π
Not involved in electronic system (aromaticity). Therefore, it has basicity and brings about stabilization against an acid. (Because protonation of an azole occurs first at the ring nitrogen atom at the 2- or 3-position,
Even in this case, the 6π electron system (aromaticity) is maintained). Reacts with acid (HF etc.) generated by decomposition of electrolyte, etc.
While removing this, it can exist stably. (Ii) A metal salt can be formed. Therefore, it can coordinate with manganese atoms on the surface of the lithium manganese composite oxide to form a film, and can function to suppress a catalytic oxidizing effect on the electrolytic solution. (Iii) Since the melting point and the boiling point are high, it is excellent in high-temperature stability as compared with other azoles. Therefore, even if the battery is used or left at high temperatures, gas generation or vaporization due to thermal decomposition hardly occurs.

Further, in the present invention, it is considered that the presence of a benzene ring in the condensed polycyclic compound (A) is preferably due to the following effects. That is, (i) the presence of a benzene ring further increases the thermal stability of the condensed polycyclic compound (A), and exhibits a further ability to suppress thermal decomposition even when the battery is used or left at high temperatures. Is done. (Ii) Resonance stabilization can be increased. (Iii) Since there are many general-purpose compounds, industrial merits are great.

As the condensed polycyclic compound (A) used in the present invention, for example, a benzimidazole skeleton or
A compound having an indazole skeleton is exemplified, but a compound having a benzimidazole skeleton is preferable, and a more preferable compound is a benzimidazole skeleton such as a compound represented by the following general formula (I) or a tautomer thereof. Is a compound having

[0016]

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Here, R _{1 to} R ₅ each independently represent a hydrogen atom, a nitro group, a cyano group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group,
sec-butyl group, tert-butyl group, vinyl group, 1
-Propenyl group, allyl group, 2-propynyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, 1-cyclohexenyl group, phenyl group,
Tolyl, xylyl, mesityl, cumenyl, benzyl, phenethyl, α-methylbenzyl, benzhydryl, trityl, styryl, cinnamyl,
Biphenylyl group, naphthyl group, anthryl group, phenanthryl group, 9-fluorenyl group, fluoro group, chloro group, bromo group, iodo group, iodosyl group, iodosyl group,
Dichloroiodo group, hydroxy group, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group,
Phenoxy group, benzyloxy group, carboxy group, methoxycarbonyl group, ethoxycarbonyl group, formyloxy group, acetoxy group, benzoyloxy group, formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, fluoroformyl group, chloroformyl Group, bromoformyl group, iodoformyl group, pyroboyl group, oxalo group, methoxalyl group, ethoxyl group, cyclohexylcarbonyl group, benzoyl group, toluoyl group, cinnamoyl group, naphthoyl group, acetonyl group, phenacyl group, salicyl group, salicyloyl group, Anisyl group, anisoyl group, benzyloxycarbonyl group, mercapto group, methylthio group, ethylthio group, phenylthio group, thioformyl group, thioacetyl group, mercaptocarbonyl group, hydroxythio Rubonyl group, dithiocarboxy group, thiocarbamoyl group, sulfino group, sulfo group, mesyl group, benzenesulfonyl group, tosyl group, sulfamoyl group, sulfoamino group, amino group, ammonium group, methylamino group, dimethylamino group, anilino group, Toluidino group, xylidino group, imino group, phenylimino group,
Isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, hydroxyamino group, hydroxyimino group, acetylamino group, benzamide group, succinimide group, phthalimide group, carbamoyl group, nitroso group, acinitro group, hydrazino group, hydrazono group , Hydrazo group, azo group, phenylazo group, naphthylazo group, azoxy group, diazo group, azido group, diazoamino group, ureido group, weylene group, amidino group, guanidide group, picryl group, pyridyl group, piperidino group, piperidyl group, or Represents a quinolyl group. Preferred among these substituents are a hydrogen atom, a nitro group, a cyano group,
Methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-
Butyl group, vinyl group, 1-propenyl group, allyl group, 2
-Propynyl group, isopropenyl group, 1-butenyl group,
2-butenyl group, cyclopropyl group, cyclobutyl group,
Cyclopentyl, cyclohexyl, 1-cyclohexenyl, phenyl, tolyl, xylyl, mesityl, cumenyl, benzyl, phenethyl, α-methylbenzyl, benzhydryl, trityl, styryl, cinnamyl , Biphenylyl group, naphthyl group,
Anthryl group, phenanthryl group, 9-fluorenyl group, fluoro group, chloro group, bromo group, iodo group, iodosyl group, iodyl group, dichloroiodo group, hydroxy group, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy Group, phenoxy group, benzyloxy group, carboxy group, methoxycarbonyl group, ethoxycarbonyl group, formyloxy group, acetoxy group, benzoyloxy group, formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, fluoroformyl group, Chloroformyl group, bromoformyl group, iodoformyl group, pyroboyl group, oxalo group, methoxalyl group,
Ethoxalyl, cyclohexylcarbonyl, benzoyl, toluoyl, cinnamoyl, naphthoyl, acetonyl, phenacyl, salicyl, salicyloyl, anisyl, anisoyl, benzyloxycarbonyl, methylthio, ethylthio, phenylthio , Thioformyl group, thioacetyl group, mercaptocarbonyl group, hydroxythiocarbonyl group, dithiocarboxy group, thiocarbamoyl group, sulfino group, sulfo group, mesyl group, benzenesulfonyl group, tosyl group, sulfamoyl group, sulfoamino group, amino group, ammonium Group, methylamino group, dimethylamino group, anilino group, toluidino group, xylidino group, imino group, phenylimino group, isocyano group, cyanato group, isocyanato group, thiocyanato group, i Thiocyanato, hydroxyamino, hydroxyimino, acetylamino, benzamide, succinimide, phthalimide, carbamoyl, nitroso, acinitro, hydrazino, hydrazono, hydrazo, azo, phenylazo, naphthylazo Azoxy group, diazo group, azide group, diazoamino group, ureido group, ureylene group, amidino group, guanidide group, picryl group, pyridyl group, piperidino group, piperidyl group, or quinolyl group, particularly preferably a hydrogen atom , A nitro group, and a methyl group.

Specific examples of these condensed polycyclic compounds (A) include, for example, benzimidazole, 5-nitroindazole, 5-nitrobenzimidazole, 5-cyanoimidazole, 5-cyanobenzimidazole, 5-benzimidazolecarboxylic acid, 4,5-dichloro-trifluoromethyl-1H-benzimidazole, 5-acetylindazole, 5-acetylbenzimidazole,
Sulfonidazole, 5-sulfobenzimidazole,
5-aldehyde indazole, 5-aldehyde benzimidazole, 5-fluoroindazole, 5-fluorobenzimidazole, 5-chloroindazole, 5-chlorobenzimidazole, 5-bromoindazole, 5
-Bromobenzimidazole, 5-iodoindazole, 5-iodobenzimidazole, 5-methylbenzimidazole, 2-aminobenzimidazole, 2-amino-5,6-dimethylbenzimidazole, 2- (allylthio) benzimidazole, 5- Aminoindazole, 2-amino-1-methylbenzimidazole, 2-
Benzimidazole acetonitrile, methyl 2-benzimidazole carbamate, 2-chlorobenzimidazole, 3-chloroindazole, 2- (chloromethyl) benzimidazole, 5,6-dimethylbenzimidazole, 2-guanidinobenzimidazole, 2-hydroxybenzimidazole , N ^1- (6-indazolyl) sulfanilamide, 5-methoxybenzimidazole, 2-methylbenzimidazole, methyl 1-
(Butylcarbamoyl) -2-benzimidazole carbamate, 2-methyl-5-nitrobenzimidazole, 2- (methylthio) benzimidazole, 2-phenylbenzimidazole, 2-phenyl-5-benzimidazolesulfonic acid, 2- ( 2-pyridyl) benzimidazole, 2- (trifluoromethyl) benzimidazole, 2,5,6-trimethylbenzimidazole and the like. Preferred are benzimidazole, 5-nitrobenzimidazole, 5-cyanobenzimidazole, 5-benzimidazolecarboxylic acid,
4,5-dichloro-trifluoromethyl-1H-benzimidazole, 5-acetylbenzimidazole, 5-
Sulfobenzimidazole, 5-aldehyde benzimidazole, 5-fluorobenzimidazole, 5-chlorobenzimidazole, 5-bromobenzimidazole, 5-iodobenzimidazole, 5-methylbenzimidazole, 2-aminobenzimidazole, 2-amino- 5,6-dimethylbenzimidazole, 2- (allylthio) benzimidazole, 2-amino-1-methylbenzimidazole, 2-benzimidazoleacetonitrile, methyl 2-benzimidazole carbamate, 2-chlorobenzimidazole, 2- (chloromethyl ) Benzimidazole, 5,6-dimethylbenzimidazole, 2-guanidinobenzimidazole, 2-hydroxybenzimidazole, N ^1- (6-indazolyl) sulfanylamido , 5-methoxybenzimidazole, 2-methylbenzimidazole, methyl 1-
(Butylcarbamoyl) -2-benzimidazole carbamate, 2-methyl-5-nitrobenzimidazole, 2- (methylthio) benzimidazole, 2-phenylbenzimidazole, 2-phenyl-5-benzimidazolesulfonic acid, 2- ( 2-pyridyl) benzimidazole, 2- (trifluoromethyl) benzimidazole, and 2,5,6-trimethylbenzimidazole. Particularly preferred are benzimidazole, 5-nitrobenzimidazole, 5-methylbenzimidazole and the like. These compounds are
Generally, it is not only inexpensive but also easy to handle because there are many powdery ones.

The above compounds may be used alone or in combination of two or more, or may be used in combination with other additives which are expected to have a synergistic effect. The amount of the above compound is usually 0.01 mol% based on the lithium manganese composite oxide.
Or more, preferably 0.1 mol% or more, more preferably 1 mol% or more. On the other hand, usually 20 mol%
Or less, preferably 10 mol% or less, more preferably 5 mol% or less. If the amount used is large, there is a possibility that other characteristics including the discharge capacity may be deteriorated. Conversely, if the amount used is small, it may be difficult to obtain the effect of improving the high temperature characteristics.

In the present invention, the lithium transition metal composite oxide is used as an active material. In the present invention, the active material is a main material that causes an electromotive reaction of the battery, and means a material that can occlude and release Li ions. That is, the lithium transition metal composite oxide may be any material that can reversibly occlude and release Li as an active material.

The lithium transition metal composite oxide used in the present invention contains at least one transition metal of manganese, nickel and cobalt and lithium. In terms of high necessity to improve high-temperature cycle characteristics among the above transition metals,
Preferably used are manganese and nickel, particularly preferably manganese. Of course, a plurality of these can be used.

Specific examples of the lithium transition metal composite oxide include a lithium manganese composite oxide, a lithium nickel composite oxide, and a lithium cobalt composite oxide. As these general composition formulas,
For example, the general formulas LiMn ₂ O ₄ , LiMnO ₂ , LiNi
O ₂ and LiCoO ₂ . Among these lithium transition metal composite oxides, the effect of the present invention is remarkable,
Lithium manganese composite oxides are preferred, and particularly the general formula L
It is preferable to use a lithium manganese composite oxide having a spinel structure as represented by iMn ₂ O ₄ .

The above composition may have a small amount of oxygen deficiency or non-stoichiometric property. Further, a part of the oxygen site may be replaced by sulfur or a halogen element. In the lithium transition metal composite oxide according to the present invention, a part of the site occupied by the transition metal may be replaced with an element other than the transition metal. As a result, the stability of the crystal structure can be improved, and by combining this with the compound, the high-temperature characteristics can be synergistically improved. This effect is particularly remarkable when a lithium manganese composite oxide is used.

At this time, the other element which substitutes a part of the transition metal site (hereinafter, referred to as a substitution element) includes A
1, Ti, V, Cr, Mn, Fe, Co, Li, Ni,
Cu, Zn, Mg, Ga, Zr, etc., and preferably, Al, Cr, Fe, Co, Li, Ni, Mg, Ga,
More preferably, it is Al. The transition metal site is 2
It may be replaced by more than one kind of other element.

When a part of the manganese site of the lithium manganese composite oxide is replaced with another element,
1, Ti, V, Cr, Fe, Co, Li, Ni, Cu,
It is preferably at least one element selected from the group consisting of Zn, Mg, Ga and Zr, and Al is particularly preferred. The substitution ratio by the substitution element is usually 2.5 mol% or more of the base transition metal element, preferably 5 mol% or more of the base transition metal element, and usually 30 mol% or less of the base transition metal element. , Preferably 20 mol% or less of the base transition metal element. If the substitution ratio is too small, the effect of improving the high-temperature cycle may not be sufficient, and if it is too large, the capacity of the battery may decrease.

The specific surface area of the lithium transition metal composite oxide used in the present invention is usually at least 0.01 m ² / g, preferably at least 0.3 m ² / g, more preferably at least 0.5 m ² / g, In addition, it is usually 10 m ² / g or less, preferably 5.
0 m ² / g or less, more preferably 3.0 m ² / g or less, particularly preferably 2.0 m ² / g or less. If the specific surface area is too small, the rate characteristics and the capacity will be reduced. If the specific surface area is too large, an undesirable reaction with the electrolytic solution or the like will be caused, and the cycle characteristics may be reduced. The measurement of the specific surface area follows the BET method.

The average particle size of the lithium transition metal composite oxide used in the present invention is usually 0.1 μm or more, preferably 0.1 μm or more.
2 μm or more, more preferably 0.3 μm or more, most preferably 0.5 μm or more, and usually 300 μm or less,
Preferably 100 μm or less, more preferably 50 μm
Or less, most preferably 20 μm or less. If the average particle size is too small, the cycle deterioration of the battery may increase, or a problem may occur in safety. If the average particle size is too large, the internal resistance of the battery may increase, making it difficult to output.

In the present invention, when a lithium secondary battery is formed using the lithium transition metal composite oxide as an active material, the condensed polycyclic compound (A) is further contained in the battery. That is, it may be present in any of the positive electrode, the negative electrode and the electrolyte layer, but is preferably contained in the positive electrode in order to sufficiently exert the effects of the present invention. When the condensed polycyclic compound (A) is present in the positive electrode, a positive electrode material containing the lithium transition metal composite oxide and the condensed polycyclic compound (A) can be used.

As a method for producing the above-mentioned positive electrode material, a method using physical mixing of a lithium transition metal and a condensed polycyclic compound,
Which form a film of the condensed polycyclic compound (A) by treatment in the presence of In addition, as a method of treating the surface of the lithium transition metal composite oxide, coating by heat treatment or the like may be mentioned, but depending on the treatment temperature at the time of coating,
The condensed polycyclic compound (A) may be lost or deteriorated,
The intended effect may be lost. Therefore, when using this method, it is necessary to carefully select the coating treatment temperature. Therefore, it is preferable to use physical mixing among these methods. Physical mixing is not only a simple and easy method without the above-mentioned temperature control, but also can sufficiently exert the effects of the present invention without fear of deterioration of the condensed polycyclic compound (A). Physical mixing in the present invention means simply mixing a plurality of substances, and means mixing without heat treatment at such a high temperature that the mixture is chemically changed. It is preferable that the condensed polycyclic compound (A) is dispersed in the positive electrode material by physical mixing. Physical mixing may be dry mixing or wet mixing. For physical mixing, a mortar, a ball mill, a jet mill, a Loedige mixer, or the like can be used.

A lithium secondary battery is formed by a positive electrode, a negative electrode, an electrolyte layer, and the like. The positive electrode according to the present invention includes a positive electrode material containing the lithium transition metal composite oxide and the condensed polycyclic compound (A), and a binder. Usually, the positive electrode is formed by forming a positive electrode layer containing the positive electrode material and a binder on a current collector. In the present invention, the lithium transition metal composite oxide and the condensed polycyclic compound (A) in the positive electrode layer are preferably dispersed and present. By being dispersed, the effects of the present invention can be sufficiently exerted.

Such a positive electrode layer can be formed by, for example, kneading a lithium transition metal composite oxide, a condensed polycyclic compound (A), a binder, and a conductive agent as necessary, and pressing the mixture on a positive electrode current collector, A slurry obtained by slurrying these solid contents with a solvent is applied to a positive electrode current collector, and then dried. As described above, the lithium transition metal composite oxide and the condensed polycyclic compound (A) may be physically mixed in advance before kneading or slurry preparation.

The positive electrode may further contain an active material capable of occluding and releasing lithium ions other than the lithium transition metal composite oxide, such as LiFePO ₄ . The ratio of the active material in the positive electrode layer is usually 10% by weight or more,
It is preferably at least 30% by weight, more preferably at least 50% by weight, usually at most 99.9% by weight, preferably at most 9% by weight.
9% by weight or less. If the amount is too large, the mechanical strength of the electrode tends to be inferior. If the amount is too small, the battery performance such as capacity tends to be inferior.

As the binder used for the positive electrode, for example, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, EPDM
(Ethylene-propylene-diene terpolymer), SB
R (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluorine rubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose and the like. The proportion of the binder in the positive electrode layer is usually 0.1% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more, usually 80% by weight or less, preferably 60% by weight or less, more preferably It is at most 40% by weight, most preferably at most 10% by weight. If the proportion of the binder is too low, the active material cannot be sufficiently retained, the mechanical strength of the positive electrode becomes insufficient, and the battery performance such as cycle characteristics may be deteriorated. Sometimes.

The positive electrode layer usually contains a conductive agent to increase conductivity. Examples of the conductive agent include graphite such as natural graphite and artificial graphite; carbon materials such as carbon black such as acetylene black; and amorphous carbon such as needle coke. The proportion of the conductive agent in the positive electrode is usually 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 1% by weight or more, and usually 50% by weight or less, preferably 30% by weight or less, It is preferably at most 15% by weight. If the proportion of the conductive agent is too low, the conductivity may be insufficient, while if it is too high, the battery capacity may be reduced.

The slurry solvent is not particularly limited as long as it dissolves or disperses the binder, but usually an organic solvent is used. For example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyl triamine, NN
-Dimethylaminopropylamine, ethylene oxide,
Tetrahydrofuran and the like can be mentioned. In addition, the active material can be slurried with a latex such as SBR by adding a dispersant, a thickener and the like to water.

The thickness of the positive electrode layer is usually 1 to 1000 μm,
Preferably it is about 10 to 200 μm. If it is too thick, the conductivity tends to decrease, and if it is too thin, the capacity tends to decrease. As a material of the current collector used for the positive electrode, aluminum, stainless steel, nickel-plated steel, or the like is used, and aluminum is preferable. The thickness of the current collector is usually 1 to 1000 μm, preferably 5 to 500 μm
It is about. If the thickness is too large, the capacity of the lithium secondary battery as a whole decreases, and if it is too small, the mechanical strength may be insufficient.

The positive electrode layer obtained by coating and drying is preferably compacted by a roller press or the like in order to increase the packing density of the active material. As the active material of the negative electrode used for the negative electrode of the secondary battery of the present invention, a lithium alloy such as lithium or a lithium aluminum alloy may be used, but a carbon material capable of absorbing and releasing lithium with higher safety is used. preferable.

The carbon material is not particularly limited. Graphite, coal-based coke, petroleum-based coke, coal-based pitch carbide, petroleum-based pitch carbide, or carbide obtained by oxidizing these pitches, needle coke, pitch coke And carbon materials such as phenolic resin and crystalline cellulose, and carbon materials partially graphitized thereof, furnace black, acetylene black, pitch-based carbon fibers, and the like.

Further, as the negative electrode active material, SnO, SnO
_Two, Sn_1-xM_xO (M = Hg, P, B, Si, Ge or
Is Sb, where 0 ≦ x <1), Sn_ThreeO_Two(OH)_Two , S
n_{3- x}M_xO_Two(OH)_Two(M = Mg, P, B, Si, G
e, Sb or Mn, provided that 0 ≦ x <3), LiSi
O_Two, SiO_TwoOr LiSnO_TwoEtc.
You. It should be noted that a mixture of two or more selected from these
It may be used as a pole active material.

The negative electrode is usually formed by forming a negative electrode layer on a current collector as in the case of the positive electrode. At this time, the same binder as that used for the positive electrode can be used as the binder, the conductive agent and the like used as needed, and the slurry solvent. As the current collector of the negative electrode, copper, nickel, stainless steel, nickel-plated steel, or the like is used, and copper is preferably used.

A separator can be interposed between the positive electrode and the negative electrode. In this case, as a separator,
Usually, a microporous polymer film is used, and as the material, it is usually made of a polyolefin polymer such as nylon, cellulose acetate, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polypropylene, polyethylene, and polybutene. Is used. Polyolefin-based polymers are preferred in terms of chemical and electrochemical stability, and polyethylene is particularly preferred in terms of self-closing temperature, which is one of the purposes of interposing a separator.

In the case of a polyethylene separator, ultrahigh molecular weight polyethylene is preferable from the viewpoint of maintaining high-temperature shape, and the lower limit of the molecular weight is preferably 500,000, more preferably 1,000,000, and most preferably 1.5 million. On the other hand, the upper limit of the molecular weight is preferably 5,000,000, more preferably 4,000,000, and most preferably 3,000,000. If the molecular weight is too large, the fluidity is too low and the pores of the separator may not be closed when heated.

As the electrolyte constituting the electrolyte layer in the lithium secondary battery of the present invention, for example, known organic electrolytes, polymer solid electrolytes, gel electrolytes, inorganic solid electrolytes and the like can be used. Organic electrolytes are preferred. The organic electrolyte is composed of an organic solvent and a solute. The organic solvent is not particularly limited, for example, carbonates, ethers, ketones, sulfolane compounds, lactones, nitriles, chlorinated hydrocarbons,
Ethers, amines, esters, amides, phosphate compounds and the like can be used. When these representatives are listed, dimethyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate, vinylene carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 4-methyl-2-pentanone, 1,2- Dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, benzonitrile, butyronitrile, Valeronitrile, 1,2-
A single solvent such as dichloroethane, dimethylformamide, dimethylsulfoxide, trimethyl phosphate, triethyl phosphate, or a mixture of two or more solvents can be used.

The above organic solvent preferably contains a high dielectric constant solvent for dissociating the electrolyte. Here, the solvent having a high dielectric constant has a relative dielectric constant of 20 at 25 ° C.
The above compounds are meant. It is preferable that ethylene carbonate, propylene carbonate, and a compound in which a hydrogen atom thereof is replaced with another element such as halogen, an alkyl group, or the like in the high dielectric constant solvent be contained in the electrolytic solution. The proportion of the high dielectric constant compound in the electrolyte is preferably 20
% By weight, more preferably 30% by weight or more, most preferably 40% by weight or more. If the content of the compound is small, desired battery characteristics may not be obtained in some cases.

As a solute to be dissolved in this solvent,
Any known, but not limited, use
Yes, LiClO_Four, LiAsF₆, LiPF₆, LiB
F_Four, LiB (C₆H_Five)_Four , LiCl, LiBr, CH_Three
SO_ThreeLi, CF_ThreeSO_ThreeLi, LiN (SO_TwoCF_Three)_Two,
LiN (SO_TwoC_TwoF_Five)_Two, LiC (SO_TwoCF_Three)_Three, L
iN (SO_ThreeCF_Three)_TwoAnd the like. This
Two or more of these may be used. Also, CO_Two , N_Two
O, CO, SO_Two Such as gas and polysulfide S_x ^2-What
Enables efficient charge and discharge of lithium ions on the negative electrode surface
Additive that produces a good film
It may be added to a single or mixed solvent.

When a solid polymer electrolyte is used, a known polymer can be used as the polymer. In particular, it is preferable to use a polymer having high ion conductivity with respect to lithium ions. For example, polyethylene oxide, polypropylene oxide, polyethylene imine, and the like are preferably used. It is also possible to add the above-mentioned solvent to the polymer together with the above-mentioned solute and use it as a gel electrolyte.

When an inorganic solid electrolyte is used,
Use of known crystalline and amorphous solid electrolytes for inorganic substances
Can be. Examples of the crystalline solid electrolyte include Li
I, Li_ThreeN, Li_{1 + x}M_xTi_2-x(PO_Four)_Three(M = A
l, Sc, Y, La), Li_{0.5- 3x}RE_{0.5 + x}TiO
_Three(RE = La, Pr, Nd, Sm) and the like.
As a crystalline solid electrolyte, for example, 4.9LiI-3
4.1Li_TwoO-61B_TwoO_Five, 33.3Li_TwoO-66.
7SiO_TwoOxide glass such as 0.45LiI-0.3
7Li_TwoS-0.26B_TwoS_Three, 0.30LiI-0.4
2Li_TwoS-0.28SiS _TwoSulfide glass etc.
Can be Use at least one of these
Can be

[0048]

The following examples further illustrate the method of the present invention.
Although the present invention will be described in detail, the present invention will
It is not limited to the embodiment. [Preparation of lithium manganese composite oxide] Spinel type
Lithium manganese composite oxide Li [Mn_1.85Al_0.11Li
_0.04] O _FourWas prepared as follows.

Starting from dimanganese trioxide (Mn ₂ O ₃ ), lithium carbonate (Li ₂ CO ₃ ) and boehmite (AlOOH), the molar ratio of each compound was 0.94:
0.52: 0.10 [Li: Mn: Al molar ratio is:
1.04: 1.88: 0.10]. This mixture was made into a uniform mixture using a jet mill. The obtained mixture is heated at 500 ° C. in the atmosphere (heating rate:
5 ° C / min), 600 ° C (heating rate: 5 ° C / mi)
n), 700 ° C (heating rate: 5 ° C / min), 800 ° C
(Tempering rate: 5 ° C./min) sequentially for 6 hours, then 900 ° C. in the atmosphere (heating rate: 5 ° C./min)
For 24 hours, and then cooled to 300 ° C:
It was cooled at a rate of 0.2 ° C./min, then slowly cooled down to room temperature by natural cooling, and taken out. Elemental analysis showed that Li [M
n _1.85 Al _0.11 Li _0.04 ] O ₄ was obtained.

Example 1 M was Li _1.04 Mn _1.85 Al _0.11 O ₄ obtained above.
Using a lithium manganese composite oxide having a cubic spinel structure in which a part of the n site is substituted by Li and Al,
To this, 5-nitrobenzimidazole was added at a ratio of 1 mol% with respect to the lithium manganese composite oxide, and the mixture was physically mixed at room temperature using a mortar to obtain a positive electrode material. The BET specific surface area of the lithium manganese composite oxide used here was 0.9 m ² / g, and the median diameter determined by laser diffraction particle size distribution measurement after ultrasonic dispersion for 5 minutes was 7.4 μm.

Example 2 The same lithium manganese composite oxide as in Example 1 was used, and 5-methylbenzimidazole was added thereto at a ratio of 1 mol% based on the lithium manganese composite oxide, and the mixture was physically mixed. The material was obtained. Example 3 The same lithium manganese composite oxide as in Example 1 was used, and benzimidazole was added thereto at a ratio of 1 mol% to the lithium manganese composite oxide and physically mixed to obtain a positive electrode material.

Comparative Example 1 A positive electrode material was obtained in the same manner as in Example 1 except that only the lithium manganese composite oxide was used as the positive electrode material, ie, 5-nitrobenzimidazole was not used. . [Test Example (Evaluation of Battery)] The batteries of Examples and Comparative Examples were evaluated by the following methods.

1. Preparation of Positive Electrode and Confirmation of Capacity A mixture of 75% by weight of the positive electrode material, 20% by weight of acetylene black and 5% by weight of polytetrafluoroethylene powder was thoroughly mixed in a mortar and thinly formed into a sheet. And punched out with a 9 mmφ or 12 mmφ punch. At this time, the total weight was adjusted to be about 8 mmg and about 18 mg, respectively. This was pressed against an Al expanded metal to form a positive electrode.

Next, the capacity of the positive electrode was confirmed. That is, 9m
A battery cell was assembled with the positive electrode punched to mφ as a test electrode and Li metal as a counter electrode. 0.5 mA / c
m ² constant current charging, that is, a reaction for releasing lithium ions from the positive electrode was performed at an upper limit of 4.35 V, and then 0.5
A constant current discharge of mA / cm ² , that is, a test for absorbing lithium ions in the positive electrode was performed at a lower limit of 3.2 V. The initial charge capacity per unit weight of the positive electrode active material at this time is Qs (C)
(MAh / g) and the initial discharge capacity is Qs (D) (mAh
/ G).

2. Preparation of Negative Electrode and Confirmation of Capacity A graphite powder (d002 = 3.35 °) having an average particle size of about 8 to 10 μm as a negative electrode active material and polyvinylidene fluoride as a binder were mixed in a weight ratio of 92.5: The mixture was weighed at a ratio of 7.5 and mixed in an N-methylpyrrolidone solution to prepare a negative electrode mixture slurry. 20 μm of this slurry
A negative electrode was applied to one side of a copper foil having a thickness, dried and evaporated to remove the solvent, punched out to a diameter of 12 mm, and pressed at 0.5 ton / cm ² .

A negative electrode active material was prepared by assembling a battery cell using the negative electrode as a test electrode and Li metal as a counter electrode, and performing a test at a lower limit of 0 V to occlude Li ions in the negative electrode at a constant current of 0.2 mA / cm ^2. The initial storage capacity per unit weight is Qf
(MAh / g). 3. Battery cell assembly Using a coin-shaped cell, battery performance was evaluated. That is,
Place the positive electrode punched to 12 mmφ on the positive electrode can,
A 25 μm porous polyethylene film was placed thereon as a separator, pressed with a polypropylene gasket, the above-mentioned negative electrode was placed, and a spacer for thickness adjustment was placed. Ethylene carbonate (EC) and lithium carbonate (DE) in which lithium fluorophosphate (LiPF ₆ ) is dissolved
A mixed solvent having a volume fraction of 3: 7 with C) was added to the inside of the battery to be sufficiently impregnated, and then the battery was sealed by mounting a negative electrode can.

At this time, the balance between the weight of the positive electrode active material and the weight of the negative electrode active material is almost the same.

[0058]

## EQU1 ## Positive electrode active material amount [g] / negative electrode active material amount [g] =
(Qf / 1.2) / Qs (C) was set.

4. Test Method In order to compare the high-temperature characteristics of the batteries obtained in this way, the 1-hour rate current value of the batteries, that is, 1 C, was measured.

[0060]

## EQU2 ## The following test was performed by setting 1 C [mA] = Qs (D) × amount of positive electrode active material [g] / [h].

First, two cycles of constant current 0.2 C charge / discharge and one cycle of constant current 1 C charge / discharge are performed at room temperature.
A test was performed at a constant temperature of 0.2C for one cycle of charge and discharge at a high temperature of ℃, and then for a constant current of 1C charge and discharge for 100 cycles. Note that the upper limit of the charge was 4.2 V and the lower limit voltage was 3.0 V. FIG. 1 shows a change in the discharge capacity at the time of 100 cycles of constant current 1C charge / discharge measurement.

At this time, the ratio of the 100th cycle discharge capacity Qh (100) to the 1st cycle discharge capacity Qh (1) in the 1C charge / discharge 100 cycle test at 50 ° C. is defined as the high-temperature cycle capacity retention ratio P, that is,

[0063]

P [%] = {Qh (100) / Qh (1)} × 100, and the high-temperature characteristics of the batteries were compared using this value.

In Example and Comparative Example, 1 at 50 ° C.
Table 1 shows the initial discharge capacity and the high-temperature cycle capacity retention ratio P in the C charge / discharge 100 cycle test.

[0065]

[Table 1]

FIG. 1 shows a cycle-discharge capacity correlation diagram in a 50 ° C. cycle test in Examples 1, 2, and 3 and Comparative Example 1. Comparison between the examples and comparative examples shows that the addition of the compound (A) specified by the present invention improves the initial capacity and the cycle characteristics at high temperatures.

[0067]

According to the present invention, it is possible to provide a positive electrode material which can be used for a lithium secondary battery excellent in high-temperature characteristics, cycle characteristics, rate characteristics, and safety and productivity. In particular, a positive electrode material having excellent cycle characteristics at high temperatures can be provided. Further, it is possible to provide a positive electrode for a lithium secondary battery and a lithium secondary battery having excellent characteristics described above.

[Brief description of the drawings]

FIG. 1 is a cycle-discharge capacity correlation diagram in a 1C charge / discharge 100 cycle test at 50 ° C.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H029 AJ04 AJ05 AK03 AL02 AL03 AL06 AL07 AL08 AL18 AM00 AM02 AM03 AM04 AM05 AM07 AM11 AM16 DJ08 DJ17 EJ11 HJ02 5H050 AA05 AA07 AA09 BA17 CA08 CA09 CB08 DA09 DA11 EA22 FA19 HA02

Claims (15)

[Claims] 1. A lithium transition metal composite oxide of at least one transition metal selected from the group consisting of Ni, Co, and Mn and lithium, and a diazole ring and benzene as a part of a ring constituting a condensed polycyclic structure. A positive electrode material for a lithium secondary battery, comprising a condensed polycyclic compound having a ring (A). 2. The positive electrode material for a lithium secondary battery according to claim 1, wherein the diazole ring constituting the condensed polycyclic compound (A) is an imidazole ring. 3. The positive electrode material for a lithium secondary battery according to claim 1, wherein the condensed polycyclic compound (A) has a benzimidazole skeleton. 4. The fused polycyclic compound (A) has the following general formula
4. The positive electrode material for a lithium secondary battery according to claim 1, which is a compound represented by (I) or a tautomer thereof. Embedded image (Wherein, R _{1 to} R ₅ each independently represent a hydrogen atom, a nitro group, a cyano group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group , Vinyl group, 1-propenyl group, allyl group, 2-propynyl group, isopropenyl group,
1-butenyl group, 2-butenyl group, cyclopropyl group,
Cyclobutyl group, cyclopentyl group, cyclohexyl group, 1-cyclohexenyl group, phenyl group, tolyl group,
Xylyl group, mesityl group, cumenyl group, benzyl group, phenethyl group, α-methylbenzyl group, benzhydryl group, trityl group, styryl group, cinnamyl group, biphenylyl group, naphthyl group, anthryl group, phenanthryl group, 9-fluorenyl group, Fluoro, chloro, bromo, iodo, iodosyl, iodyl, dichloroiodo, hydroxy, methoxy, ethoxy, propoxy, isopropoxy, butoxy, phenoxy, benzyloxy, carboxy , Methoxycarbonyl group, ethoxycarbonyl group, formyloxy group,
Acetoxy group, benzoyloxy group, formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, fluoroformyl group, chloroformyl group, bromoformyl group, iodoformyl group, pyroboyl group, oxalo group, methoxalyl group, ethoxylyl group, Cyclohexylcarbonyl group, benzoyl group, toluoyl group, cinnamoyl group, naphthoyl group, acetonyl group, phenacyl group,
Salicyl, salicyloyl, anisyl, anisoyl, benzyloxycarbonyl, mercapto, methylthio, ethylthio, phenylthio, thioformyl, thioacetyl, mercaptocarbonyl, hydroxythiocarbonyl, dithiocarboxy, thiocarbamoyl Group, sulfino group, sulfo group, mesyl group, benzenesulfonyl group, tosyl group, sulfamoyl group, sulfoamino group, amino group, ammonium group, methylamino group, dimethylamino group, anilino group, toluidino group, xylidino group, imino group, Phenylimino group, isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, hydroxyamino group, hydroxyimino group, acetylamino group, benzamide group, succinimide group, phthalate Mido group, carbamoyl group, nitroso group, acinitro group, hydrazino group, hydrazono group, hydrazo group, azo group, phenylazo group, naphthylazo group, azoxy group, diazo group, azide group, diazoamino group, ureido group, weylene group, amidino group , Guanidide group, picryl group, pyridyl group, piperidino group, piperidyl group,
Or a quinolyl group. ) 5. The fused polycyclic compound (A) is benzimidazole, 5-nitrobenzimidazole, 5-cyanobenzimidazole, 5-benzimidazolecarboxylic acid, 4,5-dichloro-trifluoromethyl-1H-benzimidazole. , 5-acetylbenzimidazole,
5-sulfobenzimidazole, 5-aldehyde benzimidazole, 5-fluorobenzimidazole, 5-
Chlorobenzimidazole, 5-bromobenzimidazole, 5-iodobenzimidazole, 5-methylbenzimidazole, 2-aminobenzimidazole, 2-
Amino-5,6-dimethylbenzimidazole, 2-
(Allylthio) benzimidazole, 2-amino-1-
Methylbenzimidazole, 2-benzimidazole acetonitrile, methyl 2-benzimidazole carbamate, 2-chlorobenzimidazole, 2- (chloromethyl) benzimidazole, 5,6-dimethylbenzimidazole, 2-guanidinobenzimidazole, 2
-Hydroxybenzimidazole, N ^1- (6-indazolyl) sulfanilamide, 5-methoxybenzimidazole, 2-methylbenzimidazole, methyl 1
-(Butylcarbamoyl) -2-benzimidazolecarbamate, 2-methyl-5-nitrobenzimidazole, 2- (methylthio) benzimidazole, 2-phenylbenzimidazole, 2-phenyl-5-benzimidazolesulfonic acid, 2- The method according to any one of claims 1 to 4, wherein the substance is selected from the group consisting of (2-pyridyl) benzimidazole, 2- (trifluoromethyl) benzimidazole, and 2,5,6-trimethylbenzimidazole. Positive electrode material for lithium secondary batteries. 6. The ratio of the condensed polycyclic compound (A) to the lithium transition metal composite oxide is 0.01 to 20 mol%.
The positive electrode material for a lithium secondary battery according to any one of claims 1 to 5, wherein 7. The positive electrode material for a lithium secondary battery according to claim 1, wherein the lithium transition metal composite oxide is a lithium manganese composite oxide. 8. The lithium secondary battery according to claim 1, wherein the lithium manganese composite oxide is a lithium manganese composite oxide in which a part of a manganese site is substituted by another element. Cathode material for battery. 9. Other elements that substitute a part of the manganese site include Al, Ti, V, Cr, Fe, Co, Li, Ni,
The positive electrode material for a lithium secondary battery according to claim 8, wherein the positive electrode material is at least one metal element selected from the group consisting of Cu, Zn, Mg, Ga, and Zr. 10. The positive electrode material for a lithium secondary battery according to claim 1, wherein the lithium manganese composite oxide has a spinel structure. 11. A positive electrode for a lithium secondary battery, comprising the positive electrode material for a lithium secondary battery according to any one of claims 1 to 10 and a binder. 12. The positive electrode according to claim 11, a negative electrode,
A lithium secondary battery having an electrolyte layer. 13. The lithium secondary battery according to claim 12, wherein the negative electrode contains a carbon material. 14. A lithium secondary battery using a lithium transition metal composite oxide having at least one transition metal selected from the group consisting of Ni, Co and Mn and lithium as a positive electrode active material, further comprising a condensed polycyclic compound A lithium secondary battery containing (A). 15. The lithium transition metal composite oxide is a lithium manganese composite oxide.
5. The lithium secondary battery according to 4.