JP2011049111A - Nonaqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide in a simple method a nonaqueous electrolyte battery having a function of suppressing for a long period an adverse effect of acid such as hydrogen fluoride generated in hydrolysis or the like of lithium salt. <P>SOLUTION: The nonaqueous electrolyte battery includes an anode having a carbon material capable of doping/undoping lithium as an anode active material, a cathode having a composite oxide between lithium and a transition metal as a cathode active material, and a nonaqueous electrolyte solution. The nonaqueous electrolyte solution contains at least one diamine compounds as expressed in a prescribed formula in a range of 0.001 wt.% or more and 5 wt.% or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte battery. More specifically, the present invention relates to a non-aqueous electrolyte battery that can be used as a lithium ion battery that exchanges lithium between positive and negative electrodes.

In recent years, research and development of nonaqueous electrolyte batteries have been actively conducted because of their excellent characteristics of being lightweight, having a high energy density, and having little self-discharge.
In particular, a lithium ion secondary battery in which a charge / discharge reaction proceeds by repeating de-doping and doping chemically and physically preliminarily doped with a negative electrode active material or a positive electrode active material is another non-aqueous electrolyte battery. Compared to lead batteries and nickel cadmium batteries, a large energy density can be obtained. Therefore, the demand for lithium ion secondary batteries is increasing as a power source installed in portable electronic devices such as mobile phones. As portable electronic devices are further reduced in size and weight, non-aqueous electrolyte batteries that are power sources are also required to be further reduced in size and energy density.

  In addition, it is desired to put hybrid cars and electric cars into practical use in order to reduce carbon dioxide emitted from automobiles, which are the distributed emission source of carbon dioxide, which is said to cause global warming. The key to this practical use is the development of a lithium ion secondary battery having a high weight energy density and volume energy density. Furthermore, in order to establish a sustainable society, it is indispensable to increase the use ratio of natural energy in the supplied energy, and solar cells are generally spread as one of the sources of natural energy. Here, as a member for storing electricity generated by the solar cell, a lithium ion secondary battery is considered as an effective member in terms of energy density and capacity. Thus, the lithium ion secondary battery affects the development of various fields.

Incidentally, a lithium ion secondary battery is generally composed of a negative electrode, a positive electrode, a separator, an electrolyte or an electrolytic solution, and a battery container for housing them. As an electrolytic solution used for the lithium ion secondary battery, carbonate ester-based nonaqueous solvents such as ethylene carbonate, propylene carbonate, and diethyl carbonate are used, and electrolyte salts such as LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO _{2) 2, LiN (C 2} F 5 SO 2) 2, LiN (CF 3 SO 2) (C 4 F 9 SO 2), LiC (CF 3 SO 2) 3, LiC (C 2 F 5 SO 2) 3 , LiAsF ₆ , LiClO ₄ , Li ₂ B ₁₀ Cl ₁₀ , Li ₂ B ₁₂ Cl _{12, and the} like and mixtures thereof are exemplified.

  However, an electrolytic solution in which a conventional electrolyte salt is dissolved cannot satisfy cycle characteristics and storage stability at the same time while having excellent conductivity. As a cause of deteriorating battery performance such as cycle characteristics and storage stability, lithium fluoride LiF and hydrogen fluoride HF generated by thermal decomposition or hydrolysis of a lithium salt in the electrolytic solution can be considered. Therefore, a technique for sufficiently suppressing the influence of hydrogen fluoride over a long period of time has been demanded.

  In response to such a demand, Japanese Patent Publication No. 2001-506052 (Patent Document 1) proposes a technique for suppressing a decomposition reaction by an acid by neutralizing an acid generated in the battery. Specifically, a technique is described in which a basic compound such as a metal-containing base, carbonate, metal oxide, hydroxide, amine, or organic base is contained in the electrolytic solution.

JP-T-2001-506052

By the way, although it can be said that the electrolytic solution in which LiPF ₆ that is relatively high in electrical conductivity and stable in potential is dissolved is an excellent electrolytic solution, this electrolytic solution has thermal stability, cycle characteristics and storage characteristics. There was a problem of being inferior. This is considered to be due to the fact that LiPF ₆ in the electrolytic solution is thermally decomposed and that lithium fluoride (LiF) and hydrogen fluoride (HF) generated by hydrolysis adversely affect the battery performance. If a minute amount of moisture is inevitably mixed in the electrolyte solution that should be non-aqueous, or if moisture is adsorbed by other battery materials, or if moisture in the battery manufacturing environment is adsorbed, Hydrolysis as shown in the reaction formula (1) occurs, and hydrogen fluoride is generated.
LiPF ₆ + H ₂ O → 2HF + LiF + POF ₃ (1)
In addition, if there are pinholes in the battery container that cannot be found at the time of battery manufacture, or if the sealing at the time of battery manufacture is insufficient, moisture will gradually enter the battery container during long-term storage or long-term use. LiPF ₆ may be hydrolyzed. The hydrogen fluoride generated in this way has a problem of deteriorating the material constituting the battery and degrading the battery performance. For example, as a result of the deterioration of the constituent materials, the charge / discharge efficiency decreases as internal resistance deteriorates.

However, in the method described in Patent Document 1, when the battery is charged / discharged, the acid is removed by decomposition of the basic compound accompanying the oxidation-reduction reaction on the electrode surface or extraction of electrons from the basic compound at the positive electrode. It was difficult to obtain the effect of neutralization in the long term. In addition, the decomposition product produced by the decomposition of the basic compound has a problem that the charge / discharge efficiency is greatly reduced.
In view of the above, an object of the present invention is to provide a nonaqueous electrolyte battery having a function of suppressing the adverse effect of an acid such as hydrogen fluoride generated by hydrolysis of a lithium salt for a long period of time by a simple method.

Thus, according to the present invention, a negative electrode having a carbon material that can be doped and dedoped with lithium as a negative electrode active material, a positive electrode having a composite oxide of lithium and a transition metal as a positive electrode active material, and a non-aqueous electrolyte Prepared,
The non-aqueous electrolyte has the chemical formula (1)

And chemical formula (2)

(In the formulas (1) and (2), E is any of —CH ₂ —, —CH═CH—, —O—, —S—, —Se—, and the substituents R _{1 to} R ₄ are A linear alkyl group having 4 to 8 carbon atoms (n = 4 to 8) or a branched alkyl group having 3 to 8 carbon atoms (n = 3 to 8) represented by C _n H _{2n + 1} , and a substituent R ₅ is a hydrogen atom or a methoxy group)
A non-aqueous electrolyte battery comprising at least one diamine compound represented by the formula: 0.001 wt% or more and 5 wt% or less is provided.

The non-aqueous electrolyte battery of the present invention includes a negative electrode having a carbon material capable of doping and dedoping lithium as a negative electrode active material, a positive electrode having a composite oxide of lithium and a transition metal as a positive electrode active material, and a non-aqueous electrolyte. And. The non-aqueous electrolyte used contains at least one diamine compound represented by the specific chemical formula (1) and / or (2) in a range of 0.001 wt% to 5 wt%.
The diamine compound having the specific structure has a property of strongly capturing an acid. Therefore, an acid such as hydrogen fluoride can be captured in the non-aqueous electrolyte. Thus, as a result of suppressing the adverse effect due to the acid, it is possible to improve the storage stability without changing the battery design and without deteriorating the charge / discharge characteristics. Moreover, since the basic site | part which reacts with an acid is covered with the substituent, the decomposition reaction of the basic substance on the electrode surface can be suppressed. Therefore, the influence of an acid can be suppressed over a long period of time. Therefore, according to the present invention, it is possible to provide a nonaqueous electrolyte battery having a function of suppressing the adverse effects of acids for a long period of time.

  In addition, if the non-aqueous electrolyte contains two or more diamine compounds and the total content of the two or more diamine compounds is in the range of 0.001 wt% or more and 5 wt% or less, the adverse effect of the acid is further suppressed. it can. As a result, it is possible to provide a nonaqueous electrolyte battery that is further excellent in cycle characteristics and storage stability.

  Furthermore, the non-aqueous electrolyte is a diamine compound represented by a chemical formula (1) or two or more diamine compounds represented by a chemical formula (2), or a diamine compound represented by a chemical formula (1) By including at least one diamine compound represented by the chemical formula (2), the adverse effect of the acid can be further suppressed. In addition, by combining diamine compounds with different capture rates, the adverse effects of acids can be suppressed over a long period of time. As a result, it is possible to provide a nonaqueous electrolyte battery that is further excellent in cycle characteristics and storage stability.

Furthermore, if the nonaqueous electrolytic solution contains at least one diamine compound represented by the chemical formula (1) and the chemical formula (2) all having the same substituents R _{1 to} R ₄ , the adverse effect of the acid is further increased. Can be suppressed. As a result, it is possible to provide a nonaqueous electrolyte battery that is further excellent in cycle characteristics and storage stability.
Furthermore, if the non-aqueous electrolyte contains at least one diamine compound represented by the chemical formula (1) and the chemical formula (2) in a range of 0.001 wt% or more and 2 wt% or less, more acid. Adverse effects can be suppressed. As a result, it is possible to provide a nonaqueous electrolyte battery that is further excellent in cycle characteristics and storage stability.
When the non-aqueous electrolyte contains LiPF ₆ , high conductivity can be realized while suppressing the adverse effect of the acid.

Hereinafter, the nonaqueous electrolyte battery according to the present invention will be specifically described.
The non-aqueous electrolyte battery of the present invention includes a negative electrode having a carbon material capable of doping and dedoping lithium as a negative electrode active material, a positive electrode having a composite oxide of lithium and a transition metal as a positive electrode active material, and a non-aqueous electrolyte. And.

(Nonaqueous electrolyte)
The nonaqueous electrolytic solution is an electrolytic solution in which an electrolyte salt is dissolved in a nonaqueous solvent.
Any conventionally known non-aqueous solvent can be used. Specific non-aqueous solvents include cyclic carbonates such as propylene carbonate and ethylene carbonate, chain carbonates such as diethyl carbonate, carboxylic acid esters such as methyl propionate and methyl butyrate, γ-butyrolactone, sulfolane, 2- And ethers such as methyltetrahydrofuran and dimethoxyethane. In particular, in view of oxidation stability, it is preferable to use a carbonate ester as the non-aqueous solvent. These non-aqueous solvents can be used alone or in combination of two or more.

As the electrolyte salt, a conventionally known one can be used. Specific electrolyte salts include LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F _{9 SO 2), LiC (CF 3} SO 2) 3, LiC (C 2 F 5 SO 2) 3, LiAsF 6, LiClO 4, Li 2 B 10 Cl 10, Li 2 B 12 Cl 12 and the like. These electrolyte salts can be used alone or in combination of a plurality of types. As the electrolyte salt, LiPF ₆ is preferably used from the viewpoint of high solubility in a non-aqueous solvent and high electrical conductivity.

  The concentration of the electrolyte salt in the non-aqueous electrolyte is 0.2 mol / l to 2.0 mol / l, or 0.2 mol / kg to 2.0 mol / kg, regardless of which electrolyte salt is used. It is preferable to be in the range. When the concentration is less than 0.2 mol / l or 0.2 mol / kg, the lithium ion concentration in the electrolyte solution is low, so that the battery performance cannot be sufficiently exhibited when performing a high rate charge / discharge reaction. is there. If it is greater than 2.0 mol / l or 2.0 mol / kg, the battery performance may be significantly reduced due to an increase in lithium ion migration resistance accompanying an increase in the electrolyte viscosity. A more preferable concentration is in the range of 0.5 mol / l to 1.5 mol / l, or in the range of 0.5 mol / kg to 1.5 mol / kg.

In non-aqueous electrolyte,
Chemical formula (1)

And chemical formula (2)

Is contained in the range of 0.001 wt% or more and 5 wt% or less.
The non-aqueous electrolyte can strongly capture the acid by dissolving the above-mentioned diamine compound. Therefore, it has a function of suppressing the adverse effect of hydrogen fluoride generated by hydrolysis of the electrolyte salt (lithium salt). Moreover, since the basic site | part which reacts with an acid is covered with the substituent, it becomes possible to suppress the decomposition reaction of the basic substance on the electrode surface, and the adverse effect of the acid can be suppressed over a long period of time.
In particular, since the chemical formulas (1) and (2) have two basic sites in the same molecule, high acid scavenging ability can be realized.

Examples of the substituents R _{1 to} R ₄ covering the basic site include linear alkyl groups having 4 to 8 carbon atoms (n = 4 to 8), branched alkyl groups having 3 to 8 carbon atoms, and the like. Specifically, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, n-hexyl group, isohexyl group, Examples include n-heptyl group, isoheptyl group, n-octyl group, isooctyl group and the like. In the following description, “n−” is omitted.
The substituents R ₅ and R ₆ are the same or different and are a hydrogen atom and a methoxy group (OMe).
The divalent group E is any one of —CH ₂ —, —CH═CH—, —O—, —S—, and —Se—.

Specifically, as a compound having a structure represented by the chemical formula (1), 1,8-bis (dibutylamino) naphthalene in which substituents R _{1 to} R ₄ are all C ₄ H ₉ and R ₅ is H, 1,8-bis (dipentylamino) naphthalene in which substituents R _{1 to} R ₄ are all C ₅ H ₁₁ and R ₅ is H, and substituents R _{1 to} R ₄ are all C ₆ H ₁₃ and R ₅ is H 1,8-bis (dihexylamino) naphthalene, 1,8-bis (diheptylamino) naphthalene in which R _{1 to} R ₄ are all C ₇ H ₁₅ and R ₅ is H, substituent R 1,8-bis (dioctylamino) naphthalene in which _{1 to} R ₄ are all C ₈ H ₁₇ and R ₅ is H, and the substituents R _{1 to} R ₄ are all isopropyl and R ₅ is 1,8 -Bis (diisopropylamino) naphthalene, the substituents R _{1 to} R ₄ are all tertiary butyl groups, and R ₅ is 1,8-bis (ditertiarybutylamino) naphthalene which is H, and 1,8-bis (dibutylamino) -2,7 where all the substituents R _{1 to} R ₄ are C ₄ H ₉ and R ₅ is OMe. -Dimethoxynaphthalene, 1,8-bis (dipentylamino) -2,7-dimethoxynaphthalene, wherein the substituents R _{1 to} R ₄ are all C ₅ H ₁₁ and R ₅ is OMe, and the substituents R _{1 to} R ₄ Are all C ₆ H ₁₃ and R ₅ is OMe, 1,8-bis (dihexylamino) -2,7-dimethoxynaphthalene, and the substituents R _{1 to} R ₄ are all C ₇ H ₁₅ and R ₅ is OMe. 1,8-bis (diheptylamino) -2,7-dimethoxynaphthalene, or 1,8-bis (dioctylamino)-, where the substituents R _{1 to} R ₄ are all C ₈ H ₁₇ and R ₅ is OMe. and 2,7-dimethoxynaphthalene, the substituents R ₁ to R ₄ are all Isopropyl, R ₅ is a OMe 1,8-or bis (diisopropylamino) -2,7-di methoxide naphthalene, all the substituents R ₁ to R ₄ tertiary butyl group, R ₅ is OMe 1, Examples include 8-bis (ditertiary butylamino) -2,7-dimethoxyquinaphthalene.

4,5-bis (dibutylamino) fluorene in which E in the chemical formula (2) is —CH ₂ — and all the substituents R _{1 to} R ₄ are C ₄ H ₉ , and the substituents R _{1 to} R ₄ are 4,5-bis (dipentylamino) fluorene, which is all C ₅ H ₁₁ , 4,5-bis (dihexylamino) fluorene, in which all the substituents R _{1 to} R ₄ are C ₆ H ₁₃ , and the substituent R ₁ Or 4,5-bis (diheptylamino) fluorene in which all R ₄ are C ₇ H ₁₅ , 4,5-bis (dioctylamino) fluorene in which all the substituents R _{1 to} R ₄ are C ₈ H ₁₇ , , all the substituents R ₁ to R ₄ is an isopropyl group 4,5-bis or (diisopropylamino) fluorene, all the substituents R ₁ to R ₄ is a tertiary butyl group 4,5-bis (di-tert-butyl Amino) fluorene and the like.

In addition, 4,5-bis (dibutylamino) phenanthrene in which E in the chemical formula (2) is —CH═CH—, and all of the substituents R _{1 to} R ₄ are C ₄ H ₉ , and the substituents R _{1 to} R ₄ 4,5-bis (dipentylamino) phenanthrene in which R ₄ is all C ₅ H ₁₁ , 4,5-bis (dihexylamino) phenanthrene in which all substituents R _{1 to} R ₄ are C ₆ H ₁₃ , substituted 4,5-bis (diheptylamino) phenanthrene in which the groups R _{1 to} R ₄ are all C ₇ H ₁₅ and 4,5-bis (dioctylamino) in which the substituents R _{1 to} R ₄ are all C ₈ H ₁₇ ) Phenanthrene, 4,5-bis (diisopropylamino) phenanthrene in which all the substituents R _{1 to} R ₄ are isopropyl groups, and 4,5-bis (wherein the substituents R _{1 to} R ₄ are all tertiary butyl groups) Ditertiary butylamino) Phenanthrene, and the like.

In addition, 1,9-bis (dibutylamino) dibenzofuran in which E in the chemical formula (2) is —O— and all the substituents R _{1 to} R ₄ are C ₄ H ₉ , and substituents R _{1 to} R _{4 are used.} 1,9-bis (dipentylamino) dibenzofuran in which all are C ₅ H ₁₁ , 1,9-bis (dihexylamino) dibenzofuran in which all of substituents R _{1 to} R ₄ are C ₆ H ₁₃ , substituent R 1,9-bis (diheptylamino) dibenzofuran in which _{1 to} R ₄ are all C ₇ H ₁₅ and 1,9-bis (dioctylamino) dibenzofuran in which all of the substituents R _{1 to} R ₄ are C ₈ H ₁₇ Or 1,9-bis (diisopropylamino) dibenzofuran in which all the substituents R _{1 to} R ₄ are isopropyl groups, and 1,9-bis (ditertiary) in which all the substituents R _{1 to} R ₄ are tertiary butyl groups. Butylamino) dibenzo Run, and the like.

In addition, 1,9-bis (dibutylamino) dibenzothiophene in which E in chemical formula (2) is —S— and all the substituents R _{1 to} R ₄ are C ₄ H ₉ , and substituents R _{1 to} R 1,9-bis (dipentylamino) dibenzothiophene in which all ₄ are C ₅ H ₁₁ , 1,9-bis (dihexylamino) dibenzothiophene in which all the substituents R _{1 to} R ₄ are C ₆ H ₁₃ , 1,9-bis (diheptylamino) dibenzothiophene in which all the substituents R _{1 to} R ₄ are C ₇ H ₁₅ , and 1,9-bis (in which all the substituents R _{1 to} R ₄ are C ₈ H ₁₇ Dioctylamino) dibenzothiophene, 1,9-bis (diisopropylamino) dibenzothiophene in which substituents R _{1 to} R ₄ are all isopropyl groups, and 1,9-bis (diisopropylamino) dibenzothiophene in which substituents R _{1 to} R ₄ are all tertiary butyl groups 9-Bis (Jitter Shari Butylamino) dibenzothiophene and the like.

In addition, 1,9-bis (dibutylamino) dibenzoselenophene in which E in the chemical formula (2) is -Se- and all the substituents R _{1 to} R ₄ are C ₄ H ₉ , and the substituents R _{1 to} R ₄ 1,9-bis (dipentylamino) dibenzoselenophene in which R ₄ is all C ₅ H ₁₁ and 1,9-bis (dihexylamino) dibenzoseleno in which all the substituents R _{1 to} R ₄ are C ₆ H ₁₃ Phen, 1,9-bis (diheptylamino) dibenzoselenophene in which all of the substituents R _{1 to} R ₄ are C ₇ H ₁₅ , and 1, 1 in which all of the substituents R _{1 to} R ₄ are C ₈ H ₁₇ 9-bis (dioctylamino) dibenzoselenophene, 1,9-bis (diisopropylamino) dibenzoselenophene in which all the substituents R _{1 to} R ₄ are isopropyl groups, and all substituents R _{1 to} R ₄ are tertiary. 1,9-bis, which is a butyl group Ditertiary butylamino) dibenzoselenophene the like.

These compounds may be used alone or in combination of two or more. For example, since the acid scavenging ability varies depending on the compound, when a compound having a fast capturing speed and a compound that captures strongly in the long term are contained, the adverse effect of the acid can be suppressed for a long time. As a combination capable of such suppression, for example,
(A) 1,8-bis (dibutylamino) naphthalene in which the substituents R _{1 to} R ₄ are all C ₄ H ₉ and R ₅ is H in the chemical formula (1), and the substituent R in the chemical formula (1) A combination of 1,8-bis (dibutylamino) -2,7-dimethoxynaphthalene in which _{1 to} R ₄ are all C ₄ H ₉ and R ₅ is OMe,
(B) 1,8-bis (dibutylamino) naphthalene in which the substituents R _{1 to} R ₄ are all C ₄ H ₉ and R ₅ is H in the chemical formula (1), and the substituent R in the chemical formula (1). A combination of 1,8-bis (ditertiarybutylamino) naphthalene in which _{1 to} R ₄ are all tertiary butyl groups and R ₅ is H can be mentioned.
Whether or not the basic site of these compounds is covered with a substituent can be confirmed by using the results of X-ray crystal structure analysis and molecular orbital calculation of conventionally known documents.

The nonaqueous electrolytic solution preferably contains the above-described diamine compound in a range of 0.001 wt% to 5 wt%. If the content is within this range, it is possible to suppress the adverse effect of the acid in the non-aqueous electrolyte. If the content is less than 0.001 wt%, the effect of suppressing the adverse effect of the acid may not be sufficiently exhibited. On the other hand, when the content exceeds 5 wt%, the viscosity of the nonaqueous electrolytic solution may increase, and the charge / discharge characteristics may deteriorate. A more preferable content is in the range of 0.001 wt% or more and 2 wt% or less.
The nonaqueous electrolytic solution may be used as a gel electrolyte by impregnating a polymer matrix. In addition to the electrolyte salt, inorganic and organic solid electrolytes can also be used.

(Negative electrode)
The negative electrode is not particularly limited as long as it has a carbon material that can be doped / undoped with lithium as a negative electrode active material. For example, a negative electrode is made by mixing a conductive material and a binder with a negative electrode active material, and adding a suitable solvent as necessary to obtain a paste-like negative electrode mixture, which is made of a metal foil such as copper. It can be formed by applying to the surface, drying, and then increasing the active material density by pressing.

  The negative electrode active material has a property of occluding lithium ions during charging and releasing during discharging. Specific examples of the negative electrode active material include lithium metal, carbon materials such as graphite or amorphous carbon, polymers such as polyacetylene and polypyrrole, and the like. Among these, it is particularly preferable to use a carbon material. Since the carbon material can increase the specific surface area and has a high lithium storage / release rate, the charge / discharge characteristics and output / regeneration density at a large current are good. In particular, the use of highly crystalline natural graphite or artificial graphite can improve the lithium ion delivery efficiency of the negative electrode.

  Examples of the conductive material include known conductive materials such as carbon black, acetylene black, and graphite. Examples of the binder include known binders such as fluorine-containing resins such as polytetrafluoroethylene, polyvinylidene fluoride, and fluorine rubber, and thermoplastic resins such as polypropylene and polyethylene. Moreover, a well-known additive can be used for a negative mix. Note that the conductive material, the binder, and the additive are not essential components.

(Positive electrode)
The positive electrode is not particularly limited as long as it has a composite oxide of lithium and a transition metal as a positive electrode active material. For example, a positive electrode is made by mixing a conductive material and a binder with a positive electrode active material and adding a suitable solvent as necessary to obtain a paste-like positive electrode mixture, which is made of a metal foil such as aluminum. It can be formed by applying to the surface, drying, and then increasing the active material density by pressing.

Examples of the positive electrode active material include Li _x MO ₂ (wherein M represents one or more transition metals, x varies depending on the charge / discharge state of the battery, and is generally 0.05 ≦ x ≦ 1.10.) Or LiFePO 4. Lithium composite oxide mainly composed of ₄ can be used. As the transition metal M constituting this lithium composite oxide, it is preferable to use Co, Ni, Mn or the like. Specific lithium composite oxides include LiCoO ₂ , LiNiO ₂ , Li _x Ni _y Co _1-y O ₂ (where x and y vary depending on the charge / discharge state of the battery, and generally 0 <x <1, 0 .7 <y <1.02), LiMn ₂ O ₄ , metal-substituted lithium manganate such as Al, Cr, lithium iron phosphate, and the like. These lithium composite oxides have a low electrical resistance, are excellent in lithium ion diffusion performance, can generate high voltages, and have high charge / discharge efficiency and good charge / discharge cycle characteristics. It is. When used as a positive electrode active material, a mixture of a plurality of these lithium composite oxides can be used.
As the conductive material and the binder, it is possible to use known conductive materials and binders as well as the negative electrode. Moreover, a conventionally well-known additive etc. can also be used for a positive electrode mixture.

(Separator)
A separator may be used as necessary. The separator is disposed between the negative electrode and the positive electrode, and prevents a short circuit due to physical contact between the negative electrode and the positive electrode. As this separator, a nonwoven fabric, a polyolefin microporous film such as polyethylene, polypropylene, or the like is used.

(Assembly of non-aqueous electrolyte battery)
A known method can be used for assembling the nonaqueous electrolyte battery. For example, a laminate-type nonaqueous electrolyte battery can be manufactured as follows. First, the negative electrode and the positive electrode are cut into predetermined dimensions, and a separator is placed between the negative electrode and the positive electrode. As a method of installing the separator, there is a method of wrapping the positive electrode with the separator. This operation is repeated, a desired number of sheets are laminated, and fixed so that the negative electrode and the positive electrode of the laminate do not shift. In addition to the laminate, a negative electrode sheet, a separator, and a positive electrode sheet may be wound to form a wound layer body.

  Next, in order to collect current from the negative electrode of the laminate or the wound layer, one end of a tab made of nickel, for example, is pressure-bonded or joined to the negative electrode current collector of the negative electrode. In addition, in order to collect current from the positive electrode of the laminate or wound layer, one end of a tab made of, for example, aluminum and nickel is pressure-bonded or joined to the positive electrode current collector of the positive electrode. The laminated body or the wound layer body is placed in the laminate film in a state where the other end of the tab formed on the laminated body or the wound layer body is disposed so as to come out of the laminated film, and the portions other than the electrolyte solution injection hole are sealed. With such a structure, conduction between the current collector tab and the external electrode is provided. A non-aqueous electrolyte battery can be produced by injecting a predetermined amount of a non-aqueous electrolyte into the laminate-type battery container thus produced, and finally sealing the electrolyte injection hole.

Although the above description is for a laminate type nonaqueous electrolyte battery, the present invention can be applied to any shape of nonaqueous electrolyte battery such as a cylindrical type, a rectangular parallelepiped type, a coin type, a card type, or the like. Is possible.
The present invention can be applied to both primary batteries and secondary batteries.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to a following example. The reagents used in the examples were lithium battery grade reagents manufactured by Kishida Chemical Co. unless otherwise specified.
Note that the compounds represented by the chemical formulas (1) and (2) used in this example are synthesizing methods described in known literature (for example, Russian Chemical Reviews 67 (1) 1 (1998)) unless otherwise specified. And identification with reference to the identification method.

<Example 1>
LiPF ₆ as an electrolyte salt was dissolved in a mixed solvent of 50% by volume of ethylene carbonate and 50% by volume of diethyl carbonate so as to be 1.0 mol / l. Further, 1,8-bis (dibutylamino) naphthalene in which all of the substituents R _{1 to} R ₄ in the chemical formula (1) are C ₄ H ₉ and R ₅ is H is mixed to the above amount so as to be 0.01 wt%. It was made to contain in a solvent and the nonaqueous electrolyte solution was obtained.
In addition, the battery container before nonaqueous electrolyte injection has the following configuration.

For the positive electrode mixture, 90 parts by weight of LiFePO _{4 as} an active material, 5 parts by weight of acetylene black as a conductive material, and 5 parts by weight of polyvinylidene fluoride as a binder are mixed, and N-methyl-2-pyrrolidone is appropriately added. And dispersed to prepare. This positive electrode mixture was uniformly applied to an aluminum current collector with a thickness of 20 μm and dried, then compressed with a roll press, and cut into a desired size to produce a positive electrode plate.

The negative electrode mixture was prepared by mixing 90 parts by weight of Chinese natural graphite and 10 parts by weight of polyvinylidene fluoride, and adding and dispersing N-methyl-2-pyrrolidone as appropriate. This negative electrode mixture was uniformly applied to a 16 μm thick copper current collector, dried, then compressed with a roll press, and cut into a desired size to produce a negative electrode plate.
For the separator, a microporous polyethylene film having a thickness of 25 microns was used.

Next, the positive electrode plate is wrapped with the separator, and alternately laminated with the negative electrode plate, a lead tab made of aluminum and nickel is welded to the positive electrode aluminum current collector, and the negative electrode copper current collector is welded to nickel. The lead tab which consists of was welded, and the laminated body which consists of a positive electrode, a negative electrode, and a separator was produced.
Next, it arrange | positioned so that the lead tab of the said laminated body might come out of the laminate film, and the outer peripheral part other than the electrolyte solution injection hole of a laminate film was heat-welded so that a laminated body might be wrapped with a laminate. Thereafter, the nonaqueous electrolyte solution was injected into the battery container, and the electrolyte solution injection hole was sealed to prepare a nonaqueous electrolyte battery.

<Example 2>
Instead of 1,8-bis (dibutylamino) naphthalene in the non-aqueous electrolyte, E is —CH ₂ — in the chemical formula (2), and the substituents R _{1 to} R ₄ are all C ₄ H ₉ . A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that 4,5-bis (dibutylamino) fluorene was used.

<Example 3>
The content ratio of 1,8-bis (dibutylamino) naphthalene in the nonaqueous electrolytic solution is 0.005 wt%. Furthermore, in chemical formula (2), E is —CH ₂ —, and substituents R _{1 to} R ₄ Is a nonaqueous electrolyte in the same manner as in Example 1 except that a nonaqueous electrolyte solution containing 4,5-bis (dibutylamino) fluorene in which the content ratio is all C ₄ H ₉ is 0.005 wt% is used. A battery was produced.

<Example 4>
The content ratio of 1,8-bis (dibutylamino) naphthalene in the nonaqueous electrolytic solution is 0.005 wt%. Further, in the chemical formula (1), the substituents R _{1 to} R ₄ are all C ₄ H ₉ , R _5. In the same manner as in Example 1, except that a nonaqueous electrolytic solution containing 1,8-bis (dibutylamino) -2,7-dimethoxynaphthalene having a content ratio of 0.005 wt%, which is OMe, was used. A water electrolyte battery was prepared.

<Example 5>
Instead of 1,8-bis (dibutylamino) naphthalene in the non-aqueous electrolyte, E is —CH ₂ — in the chemical formula (2), and the substituents R _{1 to} R ₄ are all C ₄ H ₉ . 1,5-bis (dibutylamino) fluorene in a content ratio of 0.005 wt%, in formula (2), E is —S—, and substituents R _{1 to} R ₄ are all C ₄ H ₉ A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that a nonaqueous electrolyte solution containing 9-bis (dibutylamino) dibenzothiophene at a content ratio of 0.005 wt% was used.

<Example 6>
In place of 1,8-bis (dibutylamino) naphthalene in the non-aqueous electrolyte, 1,8-bis in which all the substituents R _{1 to} R _{4 in} formula (1) are C ₈ H ₁₇ and R ₅ is H A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that (dioctylamino) naphthalene was used.

<Example 7>
A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the content ratio of 1,8-bis (dibutylamino) naphthalene in the nonaqueous electrolytic solution was 0.001 wt%.
<Example 8>
A nonaqueous electrolyte battery was produced in the same manner as in Example 1, except that the content ratio of 1,8-bis (dibutylamino) naphthalene in the nonaqueous electrolytic solution was 0.1 wt%.

<Example 9>
A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the content ratio of 1,8-bis (dibutylamino) naphthalene in the nonaqueous electrolytic solution was 1 wt%.
<Example 10>
A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the content ratio of 1,8-bis (dibutylamino) naphthalene in the nonaqueous electrolytic solution was 2 wt%.

<Comparative Example 1>
A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that 1,8-bis (dibutylamino) naphthalene was not contained in the nonaqueous electrolyte.
<Comparative Example 2>
A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that triethylamine manufactured by Kishida Chemical Co. was used instead of 1,8-bis (dibutylamino) naphthalene in the nonaqueous electrolyte. .

<Comparative Example 3>
A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the content ratio of 1,8-bis (dibutylamino) naphthalene in the nonaqueous electrolyte was 0.0001 wt%.
<Comparative example 4>
A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the content ratio of 1,8-bis (dibutylamino) naphthalene in the nonaqueous electrolyte was 6 wt%.

(Characteristic evaluation)
With respect to Examples 1 to 10 and Comparative Examples 1 to 4 produced as described above, moisture storage characteristics were evaluated as follows, and the results are shown in Table 1.
For each battery, constant current constant voltage charging at 20 ° C. and 1 A is performed up to 4.2 V, then 500 mA constant current discharging is performed up to a final voltage of 2.5 V, and the discharge capacity at this time is defined as the capacity before storage. Asked. Next, after storing for 1 month in a constant temperature and humidity chamber set at 40 ° C. and 85% RH, several cycles of charge and discharge were performed again under the same conditions, and the highest capacity value was taken as the capacity after storage. And discharge capacity maintenance factor (%) was calculated | required by following Formula.
Discharge capacity maintenance rate (%) = (capacity after storage / capacity before storage) × 100

Table 1 shows the following.
Examples 1 to 10 in which the compound represented by the chemical formula (1) or the chemical formula (2) in which the basic site is covered with the substituent are contained in the non-aqueous electrolyte solution do not contain these compounds. Compared to Comparative Example 1, the moisture-resistant storage characteristics are improved. Furthermore, compared with the comparative example 2 which contains the compound with small steric hindrance in Examples 1-10, the moisture-proof preservation characteristic is improving. Therefore, in Examples 1 to 10, even if moisture enters the evaluation cell and acid is generated, the adverse effect of the acid can be suppressed.
In addition, in Examples 1 to 10, the content of the compound represented by the chemical formula (1) or the chemical formula (2) is in the range of 0.001 wt% or more and 5 wt% or less. Compared to 4, the moisture-resistant storage characteristics are improved.

Claims (6)

A negative electrode having a carbon material capable of doping and dedoping lithium as a negative electrode active material, a positive electrode having a composite oxide of lithium and a transition metal as a positive electrode active material, and a non-aqueous electrolyte,
The non-aqueous electrolyte has the chemical formula (1)

And chemical formula (2)

(In the formulas (1) and (2), E is any of —CH ₂ —, —CH═CH—, —O—, —S—, —Se—, and the substituents R _{1 to} R ₄ are A linear alkyl group having 4 to 8 carbon atoms (n = 4 to 8) or a branched alkyl group having 3 to 8 carbon atoms (n = 3 to 8) represented by C _n H _{2n + 1} , and a substituent R ₅ is a hydrogen atom or a methoxy group)
A non-aqueous electrolyte battery comprising at least one diamine compound represented by the formula: 0.001 wt% or more and 5 wt% or less.   2. The non-aqueous electrolyte according to claim 1, wherein the non-aqueous electrolyte contains two or more of the diamine compounds, and the total content of the two or more diamine compounds is in the range of 0.001 wt% or more and 5 wt% or less. Water electrolyte battery.   The non-aqueous electrolyte is two or more kinds from the diamine compound represented by the chemical formula (1), two or more kinds from the diamine compound represented by the chemical formula (2), or the diamine represented by the chemical formula (1). The nonaqueous electrolyte battery according to claim 1 or 2, comprising at least one kind of the compound and the diamine compound represented by the chemical formula (2). The non-aqueous electrolyte is any of claims 1 to 3 which contains at least one diamine compound represented by Formula (1) and formula all have the same substituents R ₁ to R ₄ (2) The nonaqueous electrolyte battery as described in any one.   The nonaqueous electrolyte battery according to any one of claims 1 to 4, wherein the nonaqueous electrolytic solution contains the diamine compound in a range of 0.001 wt% to 2 wt%. The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte contains LiPF ₆ as an electrolyte salt.