JP2008277001A - Non-aqueous electrolytic solution and nonaqueous electrolytic solution battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic solution by which a battery having superior safety, high capacity, charge-discharge characteristic of high current density, and storage performance can be provided, and a nonaqueous electrolytic solution battery manufactured by using it. <P>SOLUTION: This is the nonaqueous electrolytic solution that is formed by containing lithium salt and room temperature molten salt, and moreover, the nonaqueous electrolytic solution contains "monofluorophosphoric acid salt and/or difluorophosphoric acid salt", and furthermore, the nonaqueous electrolytic solution battery is manufactured by using it. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte battery using the same.

  Non-aqueous electrolyte batteries such as lithium secondary batteries are being put to practical use in a wide range of applications from so-called consumer power sources such as mobile phones and notebook computers to in-vehicle power sources for automobiles and the like. However, the demand for higher performance for non-aqueous electrolyte batteries in recent years is increasing, and there is a demand for improvement in battery safety as well as battery characteristics.

  The electrolytic solution used for a non-aqueous electrolyte battery is usually composed mainly of an electrolyte and a non-aqueous solvent. The main components of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate and propylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; cyclic carboxylic acid esters such as γ-butyrolactone and γ-valerolactone. It is used.

  However, since the organic solvent is volatile and easily ignited, a non-aqueous electrolyte battery using an electrolyte containing a large amount of the organic solvent is heated, when the battery is short-circuited, when the battery is short-circuited, There is a potential danger of fire or explosion in the event of misuse or abuse, such as overcharge or overdischarge, or in an accident, especially for large batteries intended for use in automotive power supplies. The danger is extremely high.

  From such a viewpoint, a nonaqueous electrolytic solution using a room temperature molten salt (also called a room temperature molten salt or an ionic liquid) has been proposed. It is known that this room temperature molten salt is liquid so low that it cannot be detected, and it does not volatilize because it does not volatilize. Patent Document 1 discloses an attempt to obtain a non-aqueous electrolyte battery excellent in safety by using this room temperature molten salt as an electrolyte for a lithium secondary battery.

Further, in Patent Document 2, in addition to a room temperature molten salt having a quaternary ammonium cation having excellent reduction stability, a compound that undergoes reductive decomposition at a higher potential than the room temperature molten salt, such as ethylene carbonate and vinylene carbonate. By dissolving the compound, a compound that undergoes reductive decomposition at a noble potential compared to the room temperature molten salt undergoes an electrochemical reaction in the initial charge / discharge process, thereby forming an electrode protective film on the electrode active material, particularly on the negative electrode active material. It is disclosed that the charge / discharge efficiency is improved.
JP-A-4-349365 JP 2004-146346 A

  However, in recent years, there has been an increasing demand for higher performance of batteries, and it is required to achieve high capacity, high output, high-temperature storage characteristics, cycle characteristics, and high safety on a higher level. ing.

  In the non-aqueous electrolyte battery using the electrolyte described in Patent Document 1, the reversibility of the electrode reaction at the time of charge / discharge is not sufficient, so that the battery performance such as charge / discharge capacity, charge / discharge efficiency, and cycle characteristics is satisfied. It was not possible (see Comparative Examples 1 to 3). Moreover, in the non-aqueous electrolyte battery using the electrolyte solution which melt | dissolved ethylene carbonate and vinylene carbonate in the Example of patent document 2 in normal temperature molten salt, When a charge battery is hold | maintained at 80 degreeC or more In addition, the electrode protective film formed by the decomposition of ethylene carbonate or vinylene carbonate cannot suppress the decomposition of the room temperature molten salt, and the decomposition gas is remarkably generated in the battery. When cracked gas is generated in the battery, the internal pressure of the battery rises and the safety valve operates, or in a battery without a safety valve, the battery expands due to the pressure of the generated gas, and the battery itself becomes unusable. There is a case. Furthermore, when the generated gas is flammable, there is a risk that the battery may ignite or explode even if the non-aqueous electrolyte using the room temperature molten salt is not flammable.

  As described above, when the non-aqueous electrolyte using the room temperature molten salt described in Patent Document 1 and Patent Document 2 is used, it can still be satisfied in terms of both battery characteristics and safety. It wasn't.

  Accordingly, an object of the present invention is to achieve both improvement in charge and discharge efficiency and maintenance of high safety in the case of using a nonaqueous electrolytic solution using a room temperature molten salt.

  As a result of various studies to achieve the above object, the present inventors have solved the above problem by including a compound having a specific structure in a non-aqueous electrolyte using a room temperature molten salt. The present inventors have found that the present invention can be accomplished and have completed the present invention.

  That is, the gist of the present invention is a non-aqueous electrolyte solution containing a lithium salt and a room temperature molten salt, and contains a monofluorophosphate and / or difluorophosphate in the non-aqueous electrolyte solution. It exists in the non-aqueous electrolyte solution characterized by this.

  The gist of the present invention is a non-aqueous electrolyte battery comprising at least a negative electrode and a positive electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is a non-aqueous electrolyte described above. It exists in the non-aqueous electrolyte battery characterized by being electrolyte solution.

  According to the present invention, while maintaining high safety, which is the greatest advantage of a non-aqueous electrolyte solution using a room temperature molten salt, it is comparable to a non-aqueous electrolyte solution using a general-purpose non-aqueous organic solvent. The discharge capacity and charge / discharge efficiency can be achieved, and the nonaqueous electrolyte battery can be increased in size and further improved in performance.

  Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be arbitrarily modified.

[1. Non-aqueous electrolyte]
The nonaqueous electrolytic solution of the present invention contains a lithium salt and a room temperature molten salt that dissolves the lithium salt, as in the case of a conventional nonaqueous electrolytic solution, and usually contains these as the main components.

<1-1. Lithium salt>
The lithium salt in the present invention is not particularly limited as long as it is known to be used for this purpose. Any lithium salt can be used, and specific examples include the following.
LiClO ₄ ,
LiAsF ₆ ,
LiPF ₆ ,
Li ₂ CO ₃ ,
Inorganic lithium salts such as 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 ,
LiPF ₄ (CF ₃ ) ₂ ,
LiPF ₄ (C ₂ F ₅ ) ₂ ,
LiPF ₄ (CF ₃ SO ₂ ) ₂ ,
LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ ,
LiBF ₃ (CF ₃ ),
LiBF ₃ (C ₂ F ₅ ),
LiBF ₂ (CF ₃ ) ₂ ,
LiBF ₂ (C ₂ F ₅ ) ₂ ,
LiBF ₂ (CF ₃ SO ₂ ) ₂ ,
Fluorine-containing organic lithium salt such as LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ ;

Lithium bis (oxalato) borate,
Lithium tris (oxalato) phosphate,
Dicarboxylic acid complex lithium salt such as lithium difluorooxalatoborate

Among these, LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ or LiC (CF ₃ SO ₂ ) ₃ is from the point of improving battery performance. LiPF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ or LiN (C ₂ F ₅ SO ₂ ) ₂ is particularly preferable. These lithium salts may be used alone or in combination of two or more.

  The concentration of the lithium salt in the nonaqueous electrolytic solution is not particularly limited, but is usually 0.1 mol / L or more, preferably 0.2 mol / L or more, more preferably 0.3 mol / L or more. Moreover, the upper limit is 3 mol / L or less normally, Preferably it is 2 mol / L or less, More preferably, it is 1.8 mol / L or less, Most preferably, it is 1.5 mol / L or less. If the concentration of the lithium salt is too low, the electrical conductivity of the non-aqueous electrolyte may be insufficient. On the other hand, if the concentration is too high, the electrical conductivity may decrease due to an increase in viscosity, and the battery performance may be reduced. May decrease.

  The non-aqueous electrolyte solution of the present invention contains a lithium salt and a room temperature molten salt. The non-aqueous electrolyte solution contains “at least one compound selected from the group consisting of monofluorophosphates and difluorophosphates” in the non-aqueous electrolyte solution.

<1-2. Room temperature molten salt>
The “room temperature molten salt” in the present invention is an ionic substance (salt) having one molecular structure composed of one or more cations and anions, and a part of the salt at 45 ° C. Or a substance that is all liquid. Further, even if the compound has a melting point of 45 ° C. or higher by thermal analysis, it will fall within the category of the room temperature molten salt of the present invention if it exists as a liquid in a supercooled state at 45 ° C. for a long period of time by rapid cooling or the like. And Moreover, even if it is a salt which shows a solid state at 45 degreeC, it will become a liquid state at 45 degreeC by mixing with other ionic substances, such as this salt, lithium salt, monofluorophosphates, and difluorophosphates. In some cases, such salts fall within the category of room temperature molten salts of the present invention.

  The room temperature molten salt used in the present invention is not particularly limited as long as the above-mentioned requirements are satisfied. Among them, those in a liquid state at 25 ° C. are preferred, those in a liquid state at 15 ° C. are more preferred, and 10 Those which are in a liquid state at ° C are particularly preferred.

  Although the cation structure which forms a room temperature molten salt is not specifically limited, Since the cation structure which consists of organic substance tends to be in a liquid state at 45 degreeC, it is preferable. A tertiary sulfonium salt having a structure represented by the general formula (1), a quaternary ammonium salt having a structure represented by the general formula (2), and a quaternary phosphonium salt having a structure represented by the general formula (3) It is more preferable that the non-aqueous electrolyte contains at least one kind of room temperature molten salt selected from the group consisting of:

［一般式（１）中、Ｒ_１、Ｒ_２及びＲ_３は、それぞれ独立に、炭素数１〜１２の有機基を表す。ただし、Ｒ_１、Ｒ_２及びＲ_３のうち、２つの有機基が互いに結合して環構造を形成していてもよい。］

[In General Formula (1), R ₁ , R ₂ and R ₃ each independently represents an organic group having 1 to 12 carbon atoms. However, two organic groups of R ₁ , R ₂ and R ₃ may be bonded to each other to form a ring structure. ]

［一般式（２）中、Ｒ_４、Ｒ_５、Ｒ_６及びＲ_７は、それぞれ独立に、炭素数１〜１２の有機基を表す。ただし、Ｒ_４、Ｒ_５、Ｒ_６及びＲ_７のうちの２つないし４つの有機基は、互いに結合して環構造を形成していてもよく、Ｒ_４、Ｒ_５、Ｒ_６及びＲ_７のうち２つの有機基は実際には１つの有機基であって、その１つの有機基と「Ｎ^＋」原子との間が二重結合で結ばれていてもよい。］

[In General Formula (2), R ₄ , R ₅ , R ₆ and R ₇ each independently represents an organic group having 1 to 12 carbon atoms. However, two to four organic groups out of R ₄ , R ₅ , R ₆ and R ₇ may be bonded to each other to form a ring structure. R ₄ , R ₅ , R ₆ and R ₇ Of these, two organic groups are actually one organic group, and the organic group and the “N ⁺ ” atom may be linked by a double bond. ]

［一般式（３）中、Ｒ_８、Ｒ_９、Ｒ_１０及びＲ_１１は、それぞれ独立に、炭素数１〜１２の有機基を表す。ただし、Ｒ_８、Ｒ_９、Ｒ_１０及びＲ_１１のうちの２つないし４つの有機基は、互いに結合して環構造を形成していてもよく、Ｒ_８、Ｒ_９、Ｒ_１０及びＲ_１１のうち２つの有機基は実際には１つの有機基であって、その１つの有機基と「Ｐ^＋」原子との間が二重結合で結ばれていてもよい。］

[In General Formula (3), R ₈ , R ₉ , R ₁₀ and R ₁₁ each independently represents an organic group having 1 to 12 carbon atoms. However, two to four organic groups out of R ₈ , R ₉ , R ₁₀ and R ₁₁ may be bonded to each other to form a ring structure. R ₈ , R ₉ , R ₁₀ and R ₁₁ Of these, two organic groups are actually one organic group, and the one organic group and the “P ⁺ ” atom may be linked by a double bond. ]

[Compound represented by general formula (1)]
R ₁ , R ₂ and R ₃ in the sulfonium cation structure represented by the general formula (1) are each an organic group having 1 to 12 carbon atoms which may be the same as or different from each other, but R ₁ , R ₂ And R ₃ include a chain alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group or a t-butyl group; a cyclic group such as a cyclohexyl group or a norbornanyl group. Alkyl group; alkenyl group such as vinyl group, 1-propenyl group, allyl group, butenyl group, 1,3-butadienyl group; alkynyl group such as ethynyl group, propynyl group, butynyl group; trifluoromethyl group, trifluoroethyl group A halogenated alkyl group such as a hexafluoropropyl group; an aryl group such as a phenyl group optionally having a substituent such as an alkyl substituent; Aralkyl groups such as a dil group and phenylethyl group; Trialkylsilyl groups such as a trimethylsilyl group; Carbonyl group-containing alkyl groups such as an ethoxycarbonylethyl group; Methoxyethyl group, phenoxymethyl group, ethoxyethyl group, allyloxyethyl group, methoxy group Examples thereof include ether group-containing alkyl groups such as ethoxyethyl group and ethoxyethoxyethyl group; sulfonyl group-containing alkyl groups such as sulfonylmethyl group.

However, R ₁ , R ₂ and R ₃ in the sulfonium cation structure may be bonded to each other to form a ring structure. In addition to the above substituents, R ₁ , R ₂ and R ₃ may include: The substituent may be substituted by a saturated or unsaturated bond with a hetero element such as oxygen, nitrogen, sulfur, or phosphorus element.

Among R ₁ , R ₂ and R ₃ , an alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group, an allyl group, and an ether group-containing alkyl group generally have a melting point due to reduction of intermolecular interaction of the sulfonium salt. It is preferable because a low salt is easily formed.

  Among these, since the viscosity tends to be low, trimethylsulfonium, triethylsulfonium, dimethylethylsulfonium, methyldiethylsulfonium, tripropylsulfonium, dimethylpropylsulfonium, methyldipropylsulfonium, diethylpropylsulfonium, ethyldipropylsulfonium, methylethyl Propylsulfonium, tributylsulfonium, dimethylbutylsulfonium, methyldibutylsulfonium, diethylbutylsulfonium, ethyldibutylsulfonium, dipropylbutylsulfonium, propyldibutylsulfonium, methylethylbutylsulfonium, methylpropylbutylsulfonium, ethylpropylbutylsulfonium, or these One of the hydrogen atoms in the alkyl group Compound substituted with fluorine atom on top, dimethylvinylsulfonium, dimethylallylsulfonium, dimethylbutenylsulfonium, diethylvinylsulfonium, diethylallylsulfonium, diethylbutenylsulfonium, methylethylvinylsulfonium, methylethylallylsulfonium, methylethylbutenylsulfonium , Dimethylmethoxymethylsulfonium, dimethylmethoxyethylsulfonium, dimethylethoxymethylsulfonium, dimethylethoxyethylsulfonium, dimethylmethoxyethoxyethylsulfonium, dimethylethoxyethoxyethylsulfonium, diethylmethoxymethylsulfonium, diethylmethoxyethylsulfonium, diethylethoxyethylsulfonium, diethylmethoxy Etoki Ethyl sulfonium, such as diethyl ethoxy ethoxyethyl sulfonium are particularly preferred.

  The anion of the tertiary sulfonium salt having the structure represented by the general formula (1) is not particularly limited, but those having a van der Waals radius of 50 mm or more tend to be in a liquid state at 45 ° C. or less. preferable. Among these, an anion structure in which an electron-withdrawing substituent is arranged on a formally negatively charged element is more preferable because it easily becomes a liquid state at room temperature.

  Among these, the electron-withdrawing substituent is a fluorine atom; a cyano group; a carbonyl group having a fluorine, a cyano group, an alkyl group, a fluorinated alkyl group, a cyanated alkyl group, a phenyl group, a fluorinated phenyl group, or a cyanated phenyl group. And carboxyl group, sulfone group, sulfonyl group; phenyl group, fluorinated phenyl group, phenyl group having fluorinated alkyl group, cyanophenyl group; phenoxy group, fluorinated phenoxy group, phenyl group having fluorinated alkyl group, Cyanated phenoxy group; thiophenoxy group, fluorinated thiophenoxy group, thiophenoxy group having fluorinated alkyl group, cyanated thiophenoxy group; fluorinated alkoxy group, cyanated alkoxy group; fluorinated thioalkoxy group, cyanated thio What is an alkoxy group is heat resistance and oxidation resistance A particularly preferred because it is excellent.

In addition, Lewis acidic compounds such as BF ₃ , AlF ₃ , PF ₃ , PF ₅ , SbF ₅ , AsF ₅ also interact with negatively charged sites in the anion structure to give an anion with high oxidation resistance. Like the above-mentioned electron-withdrawing substituent group, it can be mentioned as a particularly preferred substituent.

Among these, BF ₄ ⁻ , AlF ₄ ⁻ have a good balance of ionic conductivity, viscosity, oxidation / reduction stability, charge / discharge efficiency, high temperature storage stability, and the like when applied to a non-aqueous electrolyte battery. , ClO ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , SiF ₆ ²⁻ , AsF ₆ ⁻ , WF ₇ ⁻ , CO ₃ ²⁻ , FSO ₃ ⁻ , (FSO ₂ ) ₂ N ⁻ , (FSO ₂ ) ₃ C ⁻ , NO ₃ ⁻ , PO ₄ ³⁻ , PO ₃ F ⁻ , PO ₂ F ₂ ⁻ , B ₁₂ F ₁₂ ²⁻ , etc., inorganic anions, (CN) ₂ N ⁻ , (CNCO) ₂ N ⁻ , (CNSO ₂₎ ) ₂ N ⁻ , (CF ₃ CO) ₂ N ⁻ , (CF ₃ CF ₂ CO) ₂ N ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ CO) (CF ₃ SO ₂ ) N ⁻ , ( CF ₃ SO ₂ ) (CF ₃ CF ₂ SO ₂ ) N ⁻ , (CF ₃ CF ₂ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) N ⁻ , cyclic 1,2-perfluoroethanedisulfonylimide, cyclic 1,3-perfluoropropane Disulfonylimide, (CN) ₃ C ⁻ , (CNCO) ₃ C ⁻ , (CNSO ₂ ) ₃ C ⁻ , (FSO ₂ ) ₃ C ⁻ , (CF ₃ CO) ₃ C ⁻ , (CF ₃ CF ₂ CO) ₃ C ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , CF ₃ BF ₃ ⁻ , CF ₃ CF ₂ BF ₃ ⁻ , CF ₃ CF ₂ CF ₂ BF ₃ ⁻ , (CF ₃ CO) BF ₃ ⁻ , (CF ₃ SO ₂ ) BF ₃ ⁻ , (CF ₃ CF ₂ SO ₂ ) BF ₃ ⁻ , (CF ₃ ) ₂ BF ₂ ⁻ , (CF ₃ CF ₂ ) ₂ BF ₂ ⁻ , (CF ₃ SO ₂ ) ₂ BF ₂ ⁻ , _(CF 3 _CF 2 _SO 2) ^{_{BF 2 -, (CF 3)}} 3 BF -, (CF 3 CF 2) 3 BF -, (CF 3 CO) 3 BF -, (CF 3 SO 2) 3 BF -, (CF 3 CF 2 SO 2) 3 ^{_{BF -, (CF 3) 4}} B -, (CF 3 CF 2) 4 B -, (C 6 F 5) 4 B -, (CF 3 CO 2) 4 B -, (CF 3 SO 3) 4 B - , (CF ₃ CF ₂ SO ₃ ) ₄ B ⁻ , ((CF ₃ ) ₃ CO) ₄ B ⁻ , ((CF ₃ ) ₂ CHO) ₄ B ⁻ , (Ph (CF ₃ ) ₂ CO) ₄ B ⁻ , (C ₆ F ₅ O) ₄ B ⁻ , (CF ₃ CO) ₄ Al ⁻ , (CF ₃ SO ₂ ) ₄ Al ⁻ , (CF ₃ CF ₂ SO ₂ ) ₄ Al ⁻ , ((CF ₃ ) ₃ CO) ^{_{4 Al -, ((CF 3}} ) 2 CHO) 4 Al -, (Ph (CF 3) 2 C ^{_{) 4 Al -, (C 6}} F 5 O) 4 Al -, (CF 3) 2 PF 4 -, (C 2 F 5) 2 PF 4 -, (CF 3 SO 2) 2 PF 4 -, (C 2 F ₅ SO ₂ ) ₂ PF ₄ ⁻ , (CF ₃ ) ₃ PF ₃ ⁻ , (C ₂ F ₅ ) ₃ PF ₃ ⁻ , (CF ₃ SO ₂ ) ₃ PF ₃ ⁻ , (C ₂ F ₅ SO ₂ ) _{3 ^{PF 3 -, (CF 3)}} 4 PF 2 -, (C 2 F 5) 4 PF 2 -, (CF 3 SO 2) 4 PF 2 -, (C 2 F 5 SO 2) 4 PF 2 - , etc. organic Dicarboxylic acid complex anions such as anions, bis (oxalato) borate, tris (oxalato) phosphate, and difluorooxalatoborate are extremely preferable.

[Compound represented by formula (2)]
R ₄ , R ₅ , R ₆ and R ₇ in the quaternary ammonium cation structure represented by the general formula (2) are the same or different organic groups having 1 to 12 carbon atoms, As R ₄ , R ₅ , R ₆ and R ₇ , the same chain alkyl group as in “R ₁ , R ₂ and R ₃ ” in the general formula (1); a cyclic alkyl group; an alkenyl group; an alkynyl group; a halogen Alkyl groups; aryl groups such as phenyl groups optionally having an alkyl substituent; aralkyl groups; trialkylsilyl groups; carbonyl group-containing alkyl groups; ether group-containing alkyl groups; sulfonyl group-containing alkyl groups Can do. Preferred specific groups are also the same as “R ₁ , R ₂ and R ₃ ” in the general formula (1).

However, two to four of R ₄ , R ₅ , R ₆ and R ₇ may be bonded to each other to form a ring structure, and R ₄ , R ₅ , R ₆ and R ₇ may be substituted with In addition to the group, the substituent may be bonded by a saturated or unsaturated bond with a hetero element such as oxygen, nitrogen, sulfur, or phosphorus element.

In the quaternary ammonium cation structure of the general formula (2) represented by the above, in the chain ammonium cation, as R ₄ , R ₅ , R ₆ and R ₇ , an alkyl group having 1 to 6 carbon atoms or a halogenated alkyl group An allyl group or an ether group-containing alkyl group is preferable because it generally tends to form a salt having a low melting point due to the reduction of the intermolecular interaction of the ammonium salt.

  Among these, since viscosity tends to be low, trimethylpropylammonium, trimethylbutylammonium, trimethylpentylammonium, trimethylhexylammonium, dimethylethylpropylammonium, dimethylethylbutylammonium, dimethylethylpentylammonium, dimethylethylhexylammonium, dimethyldipropyl Ammonium, dimethylpropylbutylammonium, dimethylpropylpentylammonium, dimethylpropylhexylammonium, dimethyldibutylammonium, dimethylbutylpentylammonium, dimethylbutylhexylammonium, dimethyldipentylammonium, dimethylpentylhexylammonium, dimethyldihexylammonium, methyl Ethylpropylammonium, methyldiethylbutylammonium, methyldiethylpentylammonium, methyldiethylhexylammonium, methylethyldipropylammonium, methylethylpropylbutylammonium, methylethylpropylpentylammonium, methylethylpropylhexylammonium, methylethyldibutylammonium, methylethyl Butylpentylammonium, methylethylbutylhexylammonium, methylethyldipentylammonium, methylethylpentylhexylammonium, methylethyldihexylammonium, methyltripropylammonium, methyldipropylbutylammonium, methyldipropylpentylammonium, methyldipropylhexylammonium Methylpropyl dibutylammonium, methylpropylbutylpentylammonium, methylpropylbutylhexylammonium, methylpropyldipentylammonium, methylpropylpentylhexylammonium, methylpropyldihexylammonium, methyltributylammonium, methyldibutylpentylammonium, methyldibutylhexylammonium, methylbutyldipentyl Ammonium, methylbutylpentylhexylammonium, methylbutyldihexylammonium, methyltripentylammonium, methyldipentylhexylammonium, methylpentyldihexylammonium, methyltrihexylammonium, triethylpropylammonium, triethylbutylammonium, triethyl Rupentylammonium, triethylhexylammonium, etc., or compounds in which one or more hydrogen atoms in these alkyl groups are substituted with fluorine atoms, trimethylallylammonium, trimethylbutenylammonium, trimethylmethoxymethylammonium, trimethylmethoxyethylammonium, trimethyl More preferred is methoxyethoxyethylammonium.

  Among them, the cation size is not too large, the number of ions per unit volume (that is, the ion density) is appropriate to the extent that the characteristics of the room temperature molten salt are not impaired, and the balance between the melting point and the viscosity is excellent, Trimethylpropylammonium, trimethylbutylammonium, trimethylpentylammonium, trimethylhexylammonium, dimethylethylpropylammonium, dimethylethylbutylammonium, dimethylethylpentylammonium, dimethylethylhexylammonium, dimethylpropylbutylammonium, dimethylpropylpentylammonium, dimethylpropylhexylammonium, Triethylpropylammonium, triethylbutylammonium, triethylpentylammonium, triethyl Hexyl ammonium, etc., and compounds obtained by substituting one or more fluorine atoms of hydrogen atoms in these alkyl groups, trimethyl allyl ammonium, trimethyl butenyl ammonium, trimethylammonium methoxymethyl ammonium, trimethyl-methoxyethyl ammonium are particularly preferred.

In the quaternary ammonium cation structure of the general formula (2), two to four of R ₄ , R ₅ , R ₆ and R ₇ may be bonded to each other to form a ring structure. Saturated heterocyclic structures represented by formula (4), general formula (5) and general formula (6) are preferred because they generally tend to form salts having a low melting point. Following general formula (4), in the general formula (5) and general formula (6), R12a, R13a, R12b, R13b, R12c, R13c is in the general formula (2), "optionally different from each other _{R 4} , R ₅ , R ₆ and R ₇ ”.

  Among the pyrrolidinium cations represented by the general formula (4), dimethyl pyrrolidinium, methyl ethyl pyrrolidinium, diethyl pyrrolidinium, methyl propyl pyrrolidinium, ethyl are generally easy to form a room temperature molten salt. Propylpyrrolidinium, dipropylpyrrolidinium, methylbutylpyrrolidinium, ethylbutylpyrrolidinium, propylbutylpyrrolidinium, dibutylpyrrolidinium, or one or more of the hydrogen atoms in these alkyl groups is fluorine Compounds substituted for atoms, methyl vinyl pyrrolidinium, ethyl vinyl pyrrolidinium, propyl vinyl pyrrolidinium, butyl vinyl pyrrolidinium, methyl allyl pyrrolidinium, ethyl allyl pyrrolidinium, propyl allyl pyrrolidinium, butyl allyl Pyrrolidine , Diallylpyrrolidinium, methylbutenylpyrrolidinium, ethylbutenylpyrrolidinium, propylbutenylpyrrolidinium, butylbutenylpyrrolidinium, dibutenylpyrrolidinium, methylmethoxymethylpyrrolidinium, methylmethoxyethyl Pyrrolidinium, methylethoxyethylpyrrolidinium, methylmethoxyethoxyethylpyrrolidinium, methylethoxyethoxyethylpyrrolidinium, ethylmethoxymethylpyrrolidinium, ethylmethoxyethylpyrrolidinium, ethylethoxyethylpyrrolidinium, ethylmethoxy Ethoxyethylpyrrolidinium, ethylethoxyethoxyethylpyrrolidinium, propylmethoxymethylpyrrolidinium, propylmethoxyethylpyrrolidinium, propylethoxyethyl Loridinium, propylmethoxyethoxyethylpyrrolidinium, propylethoxyethoxyethylpyrrolidinium, butylmethoxymethylpyrrolidinium, butylmethoxyethylpyrrolidinium, butylethoxyethylpyrrolidinium, butylmethoxyethoxyethylpyrrolidinium, butylethoxyethoxy Ethylpyrrolidinium and the like are more preferable.

  Among these, since the viscosity tends to be low, methylethylpyrrolidinium, methylpropylpyrrolidinium, ethylpropylpyrrolidinium, methylbutylpyrrolidinium, ethylbutylpyrrolidinium, or in these alkyl groups Compounds in which one or more hydrogen atoms are substituted with fluorine atoms, methylallylpyrrolidinium, ethylallylpyrrolidinium, propylallylpyrrolidinium, butylallylpyrrolidinium, methylbutenylpyrrolidinium, ethylbutenylpyrrolidi Particularly preferred are nium, propylbutenylpyrrolidinium, butylbutenylpyrrolidinium, methylmethoxymethylpyrrolidinium, methylmethoxyethylpyrrolidinium, ethylmethoxymethylpyrrolidinium, ethylmethoxyethylpyrrolidinium, and the like.

  Among piperidinium cations represented by general formula (5), dimethylpiperidinium, methylethylpiperidinium, diethylpiperidinium, methylpropylpiperidinium, ethyl are generally easy to form a room temperature molten salt. Propylpiperidinium, dipropylpiperidinium, methylbutylpiperidinium, ethylbutylpiperidinium, propylbutylpiperidinium, dibutylpiperidinium, or one or more of the hydrogen atoms in these alkyl groups is fluorine Atom-substituted compounds, methyl vinyl piperidinium, ethyl vinyl piperidinium, propyl vinyl piperidinium, butyl vinyl piperidinium, methyl allyl piperidinium, ethyl allyl piperidinium, propyl allyl piperidinium, butyl allyl Piperidinium , Diallylpiperidinium, methylbutenylpiperidinium, ethylbutenylpiperidinium, propylbutenylpiperidinium, butylbutenylpiperidinium, dibutenylpiperidinium, methylmethoxymethylpiperidinium, methylmethoxyethyl Piperidinium, methylethoxyethylpiperidinium, methylmethoxyethoxyethylpiperidinium, methylethoxyethoxyethylpiperidinium, ethylmethoxymethylpiperidinium, ethylmethoxyethylpiperidinium, ethylethoxyethylpiperidinium, ethylmethoxy Ethoxyethylpiperidinium, ethylethoxyethoxyethylpiperidinium, propylmethoxymethylpiperidinium, propylmethoxyethylpiperidinium, propylethoxyethyl Peridinium, propylmethoxyethoxyethylpiperidinium, propylethoxyethoxyethylpiperidinium, butylmethoxymethylpiperidinium, butylmethoxyethylpiperidinium, butylethoxyethylpiperidinium, butylmethoxyethoxyethylpiperidinium, butylethoxyethoxy Ethyl piperidinium and the like are more preferable.

  Among these, since the viscosity tends to be low, methylethylpiperidinium, methylpropylpiperidinium, ethylpropylpiperidinium, methylbutylpiperidinium, ethylbutylpiperidinium, or these alkyl groups Compounds in which one or more hydrogen atoms are substituted with fluorine atoms, methylallylpiperidinium, ethylallylpiperidinium, propylallylpiperidinium, butylallylpiperidinium, methylbutenylpiperidinium, ethylbutenylpiperidi Particularly preferred are nium, propylbutenylpiperidinium, butylbutenylpiperidinium, methylmethoxymethylpiperidinium, methylmethoxyethylpiperidinium, ethylmethoxymethylpiperidinium, ethylmethoxyethylpiperidinium and the like.

  Among the morpholinium cations represented by the general formula (6), dimethylmorpholinium, methylethylmorpholinium, diethylmorpholinium, methylpropylmorpholinium, ethyl are generally easy to form a room temperature molten salt. Propylmorpholinium, dipropylmorpholinium, methylbutylmorpholinium, ethylbutylmorpholinium, propylbutylmorpholinium, dibutylmorpholinium, or one or more of the hydrogen atoms in these alkyl groups is fluorine Compounds substituted with atoms, methyl vinyl morpholinium, ethyl vinyl morpholinium, propyl vinyl morpholinium, butyl vinyl morpholinium, methyl allyl morpholinium, ethyl allyl morpholinium, propyl allyl morpholinium, butyl allyl Morpholiniu , Diallylmorpholinium, methylbutenylmorpholinium, ethylbutenylmorpholinium, propylbutenylmorpholinium, butylbutenylmorpholinium, dibutenylmorpholinium, methylmethoxymethylmorpholinium, methylmethoxyethyl Morpholinium, methylethoxyethylmorpholinium, methylmethoxyethoxyethylmorpholinium, methylethoxyethoxyethylmorpholinium, ethylmethoxymethylmorpholinium, ethylmethoxyethylmorpholinium, ethylethoxyethylmorpholinium, ethylmethoxy Ethoxyethylmorpholinium, ethylethoxyethoxyethylmorpholinium, propylmethoxymethylmorpholinium, propylmethoxyethylmorpholinium, propylethoxyethyl Rupholinium, propylmethoxyethoxyethylmorpholinium, propylethoxyethoxyethylmorpholinium, butylmethoxymethylmorpholinium, butylmethoxyethylmorpholinium, butylethoxyethylmorpholinium, butylmethoxyethoxyethylmorpholinium, butylethoxyethoxy Ethylmorpholinium and the like are more preferable.

  Among these, since viscosity tends to be low, methylethylmorpholinium, methylpropylmorpholinium, ethylpropylmorpholinium, methylbutylmorpholinium, ethylbutylmorpholinium, or these alkyl groups Compounds in which one or more hydrogen atoms are substituted with fluorine atoms, methylallylmorpholinium, ethylallylmorpholinium, propylallylmorpholinium, butylallylmorpholinium, methylbutenylmorpholinium, ethylbutenylmorpholine Particularly preferred are nium, propylbutenylmorpholinium, butylbutenylmorpholinium, methylmethoxymethylmorpholinium, methylmethoxyethylmorpholinium, ethylmethoxymethylmorpholinium, ethylmethoxyethylmorpholinium and the like.

In the quaternary ammonium cation structure of the general formula (2), two organic groups out of R ₄ , R ₅ , R ₆ and R ₇ are actually one organic group, and the one organic group and “N A structure in which a “ ⁺ ” atom is connected by a double bond is also included in the general formula (2). That is, the case where two of R ₄ , R ₅ , R ₆ and R ₇ are combined to form an alkylidene group is also included in the general formula (2). Furthermore, it is preferable that the alkylidene group forms a ring structure. Among such structures, the unsaturated heterocyclic structure shown below is preferable because it generally tends to form a salt having a low melting point.

Among the pyridinium cations represented by the general formula (7), since R ₁₄ is generally easy to form a normal temperature molten salt, R ₁₄ is an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and an alkyl group thereof. A compound in which one or more hydrogen atoms are substituted with fluorine atoms, an allyl group, a butenyl group, a methoxymethyl group, a methoxyethyl group, an ethoxyethyl group, a methoxyethoxyethyl group, an ethoxyethoxyethyl group, or the like, and R _{15 to} R ₁₉ Is preferably a hydrogen atom or a methyl group.

  Among these, since the viscosity tends to be low, 1-ethylpyridinium, 1-propylpyridinium, 1-butylpyridinium, 1-pentylpyridinium, 1-hexylpyridinium, 1-allylpyridinium, 1-butenylpyridinium, 1- Methoxymethylpyridinium, 1-methoxyethylpyridinium and the like are particularly preferable.

Among the pyridazinium cations represented by the general formula (8), since R ₂₀ is generally easy to form a room temperature molten salt, R ₂₀ represents an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and alkyls thereof. compounds substituted with one or more fluorine atoms of the hydrogen atom in the group, an allyl group, a butenyl group, a methoxymethyl group, methoxyethyl group, ethoxyethyl group, methoxyethoxyethyl group, a like ethoxyethoxy ethyl group, R ₂₁ to R ₂₄ is preferably hydrogen atom or a methyl group.

  Among these, since the viscosity tends to be low, 1-ethylpyridazinium, 1-propylpyridazinium, 1-butylpyridazinium, 1-pentylpyridazinium, 1-hexylpyridazi Particularly preferred are nium, 1-allylpyridazinium, 1-butenylpyridazinium, 1-methoxymethylpyridazinium, 1-methoxyethylpyridazinium, and the like.

Among the pyrimidinium cations represented by the general formula (9), R ₂₅ is typically an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and an alkyl group thereof because it easily forms a room temperature molten salt. A compound in which one or more hydrogen atoms are substituted with fluorine atoms, an allyl group, a butenyl group, a methoxymethyl group, a methoxyethyl group, an ethoxyethyl group, a methoxyethoxyethyl group, an ethoxyethoxyethyl group, and the like, and R ₂₆ to R ₂₉ is preferably a hydrogen atom or a methyl group.

  Among these, since the viscosity tends to be low, 1-ethylpyrimidinium, 1-propylpyrimidinium, 1-butylpyrimidinium, 1-pentylpyrimidinium, 1-hexylpyrimidinium, 1-allyl Pyrimidinium, 1-butenylpyrimidinium, 1-methoxymethylpyrimidinium, 1-methoxyethylpyrimidinium and the like are particularly preferable.

Among the pyrazinium cations represented by the general formula (10), R ₃₀ is typically an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and an alkyl group thereof because it easily forms a room temperature molten salt. A compound in which one or more hydrogen atoms are substituted with fluorine atoms, an allyl group, a butenyl group, a methoxymethyl group, a methoxyethyl group, an ethoxyethyl group, a methoxyethoxyethyl group, an ethoxyethoxyethyl group, and the like, and R ₃₁ to R ₃₄ is preferably a hydrogen atom or a methyl group.

  Among these, since viscosity tends to be low, 1-ethylpyrazinium, 1-propylpyrazinium, 1-butylpyrazinium, 1-pentylpyrazinium, 1-hexylpyrazinium, 1-allyl Pyrazinium, 1-butenylpyrazinium, 1-methoxymethylpyrazinium, 1-methoxyethylpyrazinium and the like are particularly preferable.

Among the imidazolium cations represented by the general formula (11), R ₃₆ and R ₃₉ are generally easy to form a room temperature molten salt, so that R ₃₆ and R ₃₉ are ethyl group, propyl group, butyl group, pentyl group, hexyl group, and these Compounds in which one or more hydrogen atoms in the alkyl group are substituted with fluorine atoms, vinyl groups, allyl groups, butenyl groups, methoxymethyl groups, methoxyethyl groups, ethoxyethyl groups, methoxyethoxyethyl groups, ethoxyethoxyethyl groups, etc. R ₃₅ , R ₃₇ , and R ₃₈ are preferably a hydrogen atom or a methyl group.

  Among these, since the viscosity tends to be low, 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-pentyl 3-methylimidazolium, 1-hexyl 3-methylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-propylimidazolium, 1-ethyl-3-butylimidazolium, 1-ethyl-3-pentylimidazolium, 1-ethyl-3-hexylimidazolium, 1,3-dipropylimidazolium, 1-propyl-3-butylimidazolium, 1-propyl-3-pentylimidazolium, 1-hexyl-3-butylimidazolium, 1,2,3 -Trimethylimidazolium, 1-ethyl 2,3-dimethylimidazolium, 1-propyl-2,3-dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-pentyl-2,3-dimethylimidazolium, 1-hexyl-2,3-dimethylimidazole 1,3-diethyl-2-methylimidazolium, 1-propyl-2-methyl-3-ethylimidazolium, 1-butyl-2-methyl-3-ethylimidazolium, 1-pentyl-2-methyl-3-ethylimidazolium, 1 -Hexyl 2-methyl-3-ethylimidazolium, 1,2,3,4,5-hexamethylimidazolium, 1-ethyl-2,3,4,5-tetramethylimidazolium, 1-propyl-2,3,4 , 5-Tetramethylimidazolium, 1-butyl-2,3,4,5-tetramethyl Imidazolium, 1-pentyl-2,3,4,5-tetramethylimidazolium, 1-hexyl 2,3,4,5-tetramethylimidazolium, and one or more of the hydrogen atoms in these alkyl groups are fluorine 1-allyl-3-methylimidazolium, 1-allyl-3-ethylimidazolium, 1-allyl-3-propylimidazolium, 1-allyl-3-butylimidazolium, 1-allyl-2,3-dimethyl Imidazolium, 1-allyl-2,3,4,5-tetramethylimidazolium, 1-butenyl-3-methylimidazolium, 1-butenyl-3-ethylimidazolium, 1-butenyl-3-propylimidazolium, 1-butenyl-3 -Butyl imidazolium, 1-butenyl-2,3-dimethylimidazolium, 1-butenyl-2,3,4,5-tetramethylimidazolium, 1-methoxymethyl-3-methylimidazolium, 1-methoxymethyl-3-ethylimidazolium, 1-methoxymethyl-3-propylimidazolium, 1 -Methoxymethyl-3-butylimidazolium, 1-methoxymethyl-2,3-dimethylimidazolium, 1-methoxymethyl-2,3,4,5-tetramethylimidazolium, 1-methoxyethyl-3-methylimidazolium 1-methoxyethyl-3-ethylimidazolium, 1-methoxyethyl-3-propylimidazolium, 1-methoxyethyl-3-butylimidazolium, 1-methoxyethyl-2,3-dimethylimidazolium, 1- Methoxyethyl-2,3,4,5-tetramethylimidazolium, etc. Preferred.

Among the oxazolium cations represented by the general formula (12), since R ₄₁ is generally easy to form a room temperature molten salt, R ₄₁ is an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and an alkyl group thereof. A compound in which one or more hydrogen atoms are substituted with fluorine atoms, vinyl group, allyl group, butenyl group, methoxymethyl group, methoxyethyl group, ethoxyethyl group, methoxyethoxyethyl group, ethoxyethoxyethyl group, and the like, R ₄₀ , R ₄₂ and R ₄₃ are preferably a hydrogen atom or a methyl group.

  Among these, since the viscosity tends to be low, 1-ethyloxazolium, 1-propyloxazolium, 1-butyloxazolium, 1-pentyloxazolium, 1-hexyloxazolium, 1-allyl Oxazolium, 1-butenyloxazolium, 1-methoxymethyloxazolium, 1-methoxyethyloxazolium, 1-ethyl-2,4,5-trimethyloxazolium, 1-propyl-2,4,5 -Trimethyloxazolium, 1-butyl-2,4,5-trimethyloxazolium, 1-pentyl-2,4,5-trimethyloxazolium, 1-hexyl 2,4,5-trimethyloxazolium, 1- Allyl-2,4,5-trimethyloxazolium, 1-butenyl-2,4,5-trimethyloxazolium, 1-methyl Kishimechiru 2,4,5-trimethyl oxazolium, 1-methoxyethyl over 2,4,5-trimethyl oxazolium like are particularly preferred.

Among the thiazolium cations represented by the general formula (13), R ₄₅ is an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and an alkyl group thereof because it generally easily forms a room temperature molten salt. A compound in which one or more hydrogen atoms are substituted with fluorine atoms, vinyl group, allyl group, butenyl group, methoxymethyl group, methoxyethyl group, ethoxyethyl group, methoxyethoxyethyl group, ethoxyethoxyethyl group, and the like, R ₄₄ , R ₄₆ and R ₄₇ are preferably a hydrogen atom or a methyl group.

  Among these, since the viscosity tends to be low, 1-ethylthiazolium, 1-propylthiazolium, 1-butylthiazolium, 1-pentylthiazolium, 1-hexylthiazolium, 1-ary Ruthiazolium, 1-butenylthiazolium, 1-methoxymethylthiazolium, 1-methoxyethylthiazolium, 1-ethyl-2,4,5-trimethylthiazolium, 1-propyl-2,4,5 -Trimethylthiazolium, 1-butyl-2,4,5-trimethylthiazolium, 1-pentyl-2,4,5-trimethylthiazolium, 1-hexyl 2,4,5-trimethylthiazolium, 1- Allyl-2,4,5-trimethylthiazolium, 1-butenyl-2,4,5-trimethylthiazolium, 1-methoxymethyl-2,4,5-trimethyl Ruchiazoriumu, 1-methoxyethyl over 2,4,5-trimethyl thiazolium, etc. are particularly preferred.

Among the pyrazolium cations represented by the general formula (14), R ₄₉ is an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and an alkyl group thereof because it is generally easy to form a room temperature molten salt. A compound in which one or more hydrogen atoms are substituted with fluorine atoms, vinyl group, allyl group, butenyl group, methoxymethyl group, methoxyethyl group, ethoxyethyl group, methoxyethoxyethyl group, ethoxyethoxyethyl group, and the like, R ₄₈ and R _{50 to} R ₅₂ are preferably a hydrogen atom or a methyl group.

  Among these, since the viscosity tends to be low, 1-ethylpyrazolium, 1-propylpyrazolium, 1-butylpyrazolium, 1-pentylpyrazolium, 1-hexylpyrazolium, 1-allyl Pyrazolium, 1-butenylpyrazolium, 1-methoxymethylpyrazolium, 1-methoxyethylpyrazolium, 1-ethyl-2,3,4,5-tetramethylpyrazolium, 1-propyl-2 3,4,5-tetramethylpyrazolium, 1-butyl-2,3,4,5-tetramethylpyrazolium, 1-pentyl-2,3,4,5-tetramethylpyrazolium, 1-hexyl , 3,4,5-tetramethylpyrazolium, 1-allyl-2,3,4,5-tetramethylpyrazolium, 1-butenyl-2,3,4,5-tetramethylpyrazoliu , 1-methoxymethyl-over 2,3,4,5-tetramethyl-pyrazolium, 1-methoxyethyl over 2,3,4,5-tetramethyl-pyrazolium, and the like, especially preferred.

Among the triazolium cations represented by the general formula (15), since R ₅₄ is generally easy to form a normal temperature molten salt, R ₅₄ is an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and an alkyl group thereof. A compound in which one or more hydrogen atoms are substituted with fluorine atoms, vinyl group, allyl group, butenyl group, methoxymethyl group, methoxyethyl group, ethoxyethyl group, methoxyethoxyethyl group, ethoxyethoxyethyl group, and the like, R ₅₃ , R ₅₅ and R ₅₆ are preferably a hydrogen atom or a methyl group.

  Among these, since the viscosity tends to be low, 1-ethyltriazolium, 1-propyltriazolium, 1-butyltriazolium, 1-pentyltriazolium, 1-hexyltriazolium, 1-allyl Triazolium, 1-butenyltriazolium, 1-methoxymethyltriazolium, 1-methoxyethyltriazolium, 1-ethyl-2,3,4,5-tetramethyltriazolium, 1-propyl-2 3,4,5-tetramethyltriazolium, 1-butyl-2,3,4,5-tetramethyltriazolium, 1-pentyl-2,3,4,5-tetramethyltriazolium, 1-hexyl , 3,4,5-tetramethyltriazolium, 1-allyl-2,3,4,5-tetramethyltriazolium, 1-butenyl-2,3,4 Particularly preferred are 5-tetramethyltriazolium, 1-methoxymethyl-2,3,4,5-tetramethyltriazolium, 1-methoxyethyl-2,3,4,5-tetramethyltriazolium and the like. .

  The anion of the quaternary ammonium salt having the structure represented by the general formula (2) is not particularly limited, but the anion of the lithium salt or the tertiary sulfonium salt having the structure represented by the general formula (1). The thing similar to an anion is mentioned as a preferable thing.

[Compound represented by formula (3)]
R ₈ , R ₉ , R ₁₀ and R ₁₁ in the quaternary phosphonium cation structure represented by the general formula (3) are organic groups having 1 to 12 carbon atoms which may be the same as or different from each other, As R ₈ , R ₉ , R ₁₀ and R ₁₁ , the same chain alkyl group as in “R ₁ , R ₂ and R ₃ ” in the general formula (1); a cyclic alkyl group; an alkenyl group; an alkynyl group; a halogen Alkyl groups; aryl groups such as phenyl groups optionally having an alkyl substituent; aralkyl groups; trialkylsilyl groups; carbonyl group-containing alkyl groups; ether group-containing alkyl groups; sulfonyl group-containing alkyl groups Can do. Preferred specific groups are also the same as “R ₁ , R ₂ and R ₃ ” in the general formula (1).

However, two to four of R ₈ , R ₉ , R ₁₀ and R ₁₁ may be bonded to each other to form a ring structure, and R ₈ , R ₉ , R ₁₀ and R ₁₁ are the substituents described above. In addition to the above, the substituent may be bonded by a saturated or unsaturated bond with a hetero element such as oxygen, nitrogen, sulfur, or phosphorus element.

Furthermore, in the quaternary phosphonium cation structure of the general formula (3), two organic groups of R ₈ , R ₉ , R ₁₀ and R ₁₁ are actually one organic group, and the one organic group and A structure in which a “P ⁺ ” atom is connected by a double bond is also included in the general formula (3). That is, the case where two of R ₈ , R ₉ , R ₁₀ and R ₁₁ are combined to form an alkylidene group is also included in the general formula (3).

Among R ₈ to R ₁₀ , an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, an allyl group, or an ether group-containing alkyl group is generally a salt having a low melting point by reducing the intermolecular interaction of the phosphonium salt. It is preferable because it is easy to form.

  Among these, since the viscosity tends to decrease, triethylbutylphosphonium, triethylpentylphosphonium, triethylhexylphosphonium, triethylheptylphosphonium, triethyloctylphosphonium, diethylpropylbutylphosphonium, diethylpropylpentylphosphonium, diethylpropylhexylphosphonium, diethylpropylheptyl Phosphonium, diethylpropyloctylphosphonium, diethylbutylpentylphosphonium, diethylbutylhexylphosphonium, diethylbutylheptylphosphonium, diethylbutyloctylphosphonium, diethylpentylhexylphosphonium, diethylpentylheptylphosphonium, diethylpentyloctylphosphonium, diethylhexylhept Ruphosphonium, diethylhexyloctylphosphonium, diethylheptyloctylphosphonium, diethyldioctylphosphonium, ethyldipropylbutylphosphonium, ethyldipropylpentylphosphonium, ethyldipropylhexylphosphonium, ethyldipropylheptylphosphonium, ethyldipropyloctylphosphonium, ethylpropyldibutyl Phosphonium, ethylpropylbutylpentylphosphonium, ethylpropylbutylhexylphosphonium, ethylpropylbutylheptylphosphonium, ethylpropylbutylpeoctylphosphonium, ethylpropyldipentylphosphonium, ethylpropylpentylhexylphosphonium, ethylpropylpentylheptylphosphonium, ethylpropylpenty Octyl phosphonium, ethyl propyl dihexyl phosphonium, ethyl propyl hexyl heptyl phosphonium, ethyl propyl hexyl octyl phosphonium, ethyl propyl diheptyl phosphonium, ethyl propyl heptyl octyl phosphonium, ethyl propyl dioctyl phosphonium, ethyl tributyl phosphonium, ethyl dibutyl pentyl phosphonium, ethyl dibutyl hexyl phosphonium , Ethyl dibutyl heptyl phosphonium, ethyl dibutyl octyl phosphonium, ethyl butyl dipentyl phosphonium, ethyl butyl pentyl hexyl phosphonium, ethyl butyl pentyl heptyl phosphonium, ethyl butyl pentyl octyl phosphonium, ethyl butyl dihexyl phosphonium, ethyl butyl hexyl heptyl Ruphosphonium, ethyl butylhexyl octyl phosphonium, ethyl butyl heptyl octyl phosphonium, ethyl butyl dioctyl phosphonium, ethyl tripentyl phosphonium, ethyl dipentyl hexyl phosphonium, ethyl dipentyl heptyl phosphonium, ethyl dipentyl octyl phosphonium, ethyl pentyl dihexyl phosphonium, ethyl pentyl hexyl heptyl phosphonium , Ethylpentylhexyloctylphosphonium, ethylpentyldiheptylphosphonium, ethylpentylheptyloctylphosphonium, ethylpentyldioctylphosphonium, ethyltrihexylphosphonium, ethyldihexylheptylphosphonium, ethyldihexyloctylphosphonium, ethylhexyldiheptylphosphonium , Ethylhexyl heptyl octyl phosphonium, ethyl hexyl dioctyl phosphonium, ethyl triheptyl phosphonium, ethyl diheptyl octyl phosphonium, ethyl heptyl dioctyl phosphonium, ethyl trioctyl phosphonium, tripropyl butyl phosphonium, tripropyl pentyl phosphonium, tripropyl hexyl phosphonium, tripropyl heptyl Phosphonium, tripropyloctylphosphonium, dipropyldibutylphosphonium, dipropylbutylpentylphosphonium, dipropylbutylhexylphosphonium, dipropylbutylheptylphosphonium, dipropylbutyloctylphosphonium, dipropyldipentylphosphonium, dipropylpentylhexylphosphonium, dipropyl N-heptylphosphonium, dipropylpentyloctylphosphonium, dipropyldihexylphosphonium, dipropylhexylheptylphosphonium, dipropylhexyloctylphosphonium, dipropyldiheptylphosphonium, dipropylheptyloctylphosphonium, dipropyldioctylphosphonium, propyltributylphosphonium, propyl Dibutylpentylphosphonium, propyldibutylhexylphosphonium, propyldibutylheptylphosphonium, propyldibutyloctylphosphonium, propylbutyldipentylphosphonium, propylbutylpentylhexylphosphonium, propylbutylpentylheptylphosphonium, propylbutylpentyloctylphosphonium, propylbutyldiheptyl Ruphosphonium, propyl butyl heptyl octyl phosphonium, propyl butyl dioctyl phosphonium, propyl tripentyl phosphonium, propyl dipentyl hexyl phosphonium, propyl dipentyl heptyl phosphonium, propyl dipentyl hexyl phosphonium, propyl pentyl hexyl phosphonium, propyl pentyl hexyl octyl phosphonium, propyl pentyl di Heptylphosphonium, propylpentylheptyloctylphosphonium, propylpentyldioctylphosphonium, propyltrihexylphosphonium, propyldihexylheptylphosphonium, propyldihexyloctylphosphonium, propylhexyldiheptylphosphonium, propylhexylheptyloctylphosphonium Propylhexyl dioctyl phosphonium, propyl triheptyl phosphonium, propyl diheptyl octyl phosphonium, propyl heptyl dioctyl phosphonium, propyl trioctyl phosphonium, tetrabutyl phosphonium, tributyl pentyl phosphonium, tributyl hexyl phosphonium, tributyl heptyl phosphonium, tributyl octyl phosphonium, tetrapentyl Phosphonium, tripentylhexylphosphonium, tripentylheptylphosphonium, tripentyloctylphosphonium, tetrahexylphosphonium, trihexylheptylphosphonium, trihexyloctylphosphonium, tetraheptylphosphonium, triheptyloctylphosphonium, tetraoctylphosphonium, etc. Are compounds in which one or more hydrogen atoms in these alkyl groups are substituted with fluorine atoms, triethylallylphosphonium, triethylbutenylphosphonium, tripropylallylphosphonium, tripropylbutenylphosphonium, tributylallylphosphonium, tributylbutenylphosphonium, Triethylmethoxyethylphosphonium, triethylmethoxyethoxyethylphosphonium, tripropylmethoxyethylphosphonium, tripropylmethoxyethoxyethylphosphonium, tributylmethoxyethylphosphonium, tributylmethoxyethoxyethylphosphonium are more preferable.

  Among these, the number of ions per unit volume (that is, the ion density) is appropriate so as not to impair the characteristics of the room temperature molten salt, and has an excellent balance with the melting point and viscosity, so that triethylbutylphosphonium, triethylpentylphosphonium , Triethylhexylphosphonium, triethylheptylphosphonium, triethyloctylphosphonium, tripropylbutylphosphonium, tripropylpentylphosphonium, tripropylhexylphosphonium, tripropylheptylphosphonium, tripropyloctylphosphonium, tetrabutylphosphonium, tributylpentylphosphonium, tributylhexylphosphonium, Tributyl heptyl phosphonium, tributyl octyl phosphonium, tetrapentyl phosphonium, tripe Tylhexylphosphonium, tripentylheptylphosphonium, tripentyloctylphosphonium, tetrahexylphosphonium, trihexylheptylphosphonium, trihexyloctylphosphonium, tetraheptylphosphonium, triheptyloctylphosphonium, tetraoctylphosphonium, etc., and hydrogen atoms in these alkyl groups Compounds substituted with one or more fluorine atoms, triethylallylphosphonium, triethylbutenylphosphonium, tripropylallylphosphonium, tripropylbutenylphosphonium, tributylallylphosphonium, tributylbutenylphosphonium, triethylmethoxyethylphosphonium, triethylmethoxyethoxyethylphosphonium , Tripropylmethoxyethylphosphonic , Tripropylamine methoxyethoxyethyl phosphonium, tributyl methoxyethyl phosphonium, tributyl methoxyethoxyethyl phosphonium is particularly preferred.

  The anion of the quaternary phosphonium salt having the structure represented by the general formula (3) is not particularly limited, but the anion of the lithium salt or the tertiary sulfonium salt having the structure represented by the general formula (1). The thing similar to the anion or the anion of the quaternary ammonium salt which has a structure represented by the said General formula (2) is mentioned as a preferable thing.

  The non-aqueous solvent in the non-aqueous electrolyte solution in the present invention may contain a conventionally known solvent for the non-aqueous electrolyte solution as long as the effects of the present invention are not impaired. In that case, it can be used by appropriately selecting from known non-aqueous electrolyte solutions. For example, room temperature molten salts and chain carbonates, room temperature molten salts and cyclic carbonates, room temperature molten salts and cyclic esters, room temperature molten salts and cyclic sulfones, room temperature molten salts and fluorinated chain ethers, room temperature molten salts and Combinations mainly composed of fluorinated chain carbonates, room temperature molten salts and polysiloxanes having a molecular weight of about 500 to 3000, room temperature molten salts and polyethers having a molecular weight of about 700 to 3000, room temperature molten salts and phosphate esters, etc. It is mentioned as preferable.

  The ambient temperature molten salt is contained in an amount of 0.01% by mass or more and 100% by mass or less with respect to the non-aqueous electrolyte component other than the lithium salt and “monofluorophosphate and difluorophosphate” described later. preferable. “Non-aqueous electrolyte components other than lithium salt and“ monofluorophosphate, difluorophosphate ”” include, for example, linear or cyclic carbonates, linear or cyclic esters, linear or cyclic sulfones, Examples thereof include “high-boiling solvents and nonflammable solvents” such as chain or cyclic ethers, fluorinated compounds thereof, polysiloxanes, and polyethers. Moreover, the nonaqueous solvent mentioned later is mentioned.

  The content of the ambient temperature molten salt is more preferably 50% by mass or more and 100% by mass or less, particularly preferably 60% by mass or more and 95% by mass or less, and more preferably 70% by mass or more and 90% by mass with respect to the entire component. The following is more preferable. If there is too little room temperature molten salt, the non-aqueous electrolyte may not be able to obtain safety effects such as non-flammability and high thermal stability, while if it is too much, the viscosity may vary depending on the structure of the room temperature molten salt. If it is too high, the ionic conductivity may decrease, or the non-aqueous electrolyte may not easily penetrate into the separator, the positive electrode, and the negative electrode.

  In the present invention, one preferred combination of the non-aqueous solvent containing a room temperature molten salt is a combination mainly composed of a room temperature molten salt and a cyclic carbonate. Among them, the ratio of the room temperature molten salt in the non-aqueous solvent is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and usually 95% by mass or less, preferably 90% by mass or less, more Preferably it is 85 mass% or less. When this non-aqueous solvent combination is used, the viscosity of the non-aqueous electrolyte solution is lower than when only room temperature molten salt is used as the non-aqueous electrolyte solution solvent, and a good film is formed on the negative electrode surface on the cyclic carbonate. Therefore, it is preferable because a charge / discharge capacity and cycle characteristics at a high current density of a battery produced using the same are improved.

  Specific examples of preferred combinations of the room temperature molten salt and “cyclic carbonates, cyclic esters, and cyclic sulfones” include, for example, room temperature molten salt and ethylene carbonate, room temperature molten salt and propylene carbonate, room temperature molten salt and fluoroethylene carbonate, Room temperature molten salt and butylene carbonate, room temperature molten salt and γ-butyrolactone, room temperature molten salt and γ-valerolactone, room temperature molten salt and sulfolane, room temperature molten salt and fluorosulfolane, and the like.

  Another preferable combination is a combination mainly composed of a room temperature molten salt and a fluorinated chain ether. Among them, the ratio of the room temperature molten salt in the non-aqueous solvent is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and usually 95% by mass or less, preferably 90% by mass or less, more Preferably it is 85 mass% or less. When this combination of non-aqueous solvents is used, the viscosity of the non-aqueous electrolyte decreases as compared with the case where only the normal temperature molten salt is used as the solvent of the non-aqueous electrolyte without impairing the nonflammability of the normal temperature molten salt. Furthermore, since the non-aqueous electrolyte solution easily penetrates into the pores of the positive electrode and the negative electrode, the charge / discharge capacity at a high current density of a battery produced using this is improved, which is preferable.

  Specific examples of preferred combinations of room temperature molten salts and fluorinated chain ethers include, for example, room temperature molten salts and nonafluorobutyl methyl ether, room temperature molten salts and nonafluorobutyl ethyl ether, room temperature molten salts and trifluoroethoxyethoxymethane. Room temperature molten salt and trifluoroethoxyethoxyethane, room temperature molten salt and hexafluoroethoxyethoxymethane, room temperature molten salt and hexafluoroethoxyethoxyethane, and the like.

  Specific examples of preferable combinations of room temperature molten salt and phosphate esters include, for example, room temperature molten salt and trimethyl phosphate, room temperature molten salt and triethyl phosphate, room temperature molten salt and dimethylethyl phosphate, room temperature molten salt and phosphoric acid Methyl diethyl, room temperature molten salt and tristrifluoroethyl phosphate, room temperature molten salt and ethylene methyl phosphate, room temperature molten salt and ethylene ethyl phosphate, room temperature molten salt and trihexyl phosphate, room temperature molten salt and trioctyl phosphate, etc. It is done.

<1-3. Monofluorophosphate, Difluorophosphate>
The nonaqueous electrolytic solution in the present invention contains “monofluorophosphate and / or difluorophosphate” in addition to the above-described lithium salt and room temperature molten salt.

  The counter cation of monofluorophosphate and difluorophosphate is not particularly limited, but is represented by the general formula (1) in addition to metal elements such as Li, Na, K, Mg, Ca, Fe, and Cu. Examples include tertiary sulfonium, quaternary ammonium represented by the general formula (2), and quaternary phosphonium represented by the general formula (3). Here, the counter cation represented by the general formulas (1) to (3) has the same structure as that used in the room temperature molten salt.

  Among these counter cations, lithium, sodium, potassium, magnesium, calcium, tertiary sulfonium, quaternary ammonium, and quaternary phosphonium are preferable, and lithium is particularly preferable from the viewpoint of battery characteristics when used in a non-aqueous electrolyte battery. .

  Among monofluorophosphates and difluorophosphates, difluorophosphate is preferable from the viewpoint of battery cycle characteristics, high-temperature storage characteristics, and the like, and lithium difluorophosphate is particularly preferable. In addition, those compounds synthesized in a non-aqueous solvent may be used as they are, or those synthesized separately and substantially isolated are added in a non-aqueous solvent or a non-aqueous electrolyte. May be.

  There is no limit to the amount of “monofluorophosphate and / or difluorophosphate” added to the entire non-aqueous electrolyte of the present invention, and it is optional as long as the effects of the present invention are not significantly impaired. The total amount of the electrolyte is generally 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 20% by mass or less, preferably 10%. It is contained at a concentration of not more than mass%, more preferably not more than 5 mass%. If it is too much, it may be deposited at low temperatures to deteriorate the battery characteristics. On the other hand, if it is too small, the effect of improving the cycle characteristics, high temperature storage characteristics, etc. may be significantly reduced. However, when the monofluorophosphate and / or difluorophosphate also serves as a room temperature molten salt, it is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, Further, it is usually contained at a concentration of 100% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less, and particularly preferably 85% by mass or less. If the amount is too large, the viscosity of the non-aqueous electrolyte may increase and the ionic conductivity may decrease, or it may be difficult to penetrate the separator, the positive electrode, and the negative electrode. On the other hand, if the amount is too small, the effect of improving the low temperature characteristics, cycle characteristics, high temperature storage characteristics, etc. may be significantly reduced as described above.

<1-4. Other compounds>
The nonaqueous electrolytic solution of the present invention can contain “other compounds” as long as the effects of the present invention are not impaired. Examples of such “other compounds” include various compounds such as conventionally known negative electrode film forming agents, positive electrode protective agents, overcharge inhibitors, and auxiliary agents.

<1-4-1. Negative electrode film-forming agent>
By including the negative electrode film forming agent, the reversibility of the lithium ion reaction in the negative electrode can be improved, and the charge / discharge capacity, charge / discharge efficiency, and cycle characteristics can be improved. As the negative electrode film forming agent, for example, vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate and the like are preferable. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  The content ratio of these negative electrode film forming agents in the non-aqueous electrolyte solution is not particularly limited, but is 0.01% by mass or more, preferably 0.1% by mass or more, more preferably, based on the whole non-aqueous electrolyte solution. Is 0.2 mass% or more, and the upper limit is 12 mass% or less, preferably 10 mass% or less, more preferably 8 mass% or less.

<1-4-2. Positive electrode protective agent>
By containing a positive electrode protective agent, capacity maintenance after high temperature storage and cycle characteristics can be improved. As the positive electrode protective agent, ethylene sulfite, propylene sulfite, propane sultone, butane sultone, methyl methanesulfonate, busulfan and the like are preferable. Two or more of these may be used in combination.

  The content ratio of these positive electrode protective agents in the non-aqueous electrolyte solution is not particularly limited, but is 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 0% with respect to the whole non-aqueous electrolyte solution. The upper limit is 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less.

<1-4-3. Overcharge prevention agent>
By containing an overcharge preventing agent, rupture / ignition of the battery can be suppressed during overcharge or the like.

As a specific example of the overcharge inhibitor, for example,
Partially hydrogenated compounds such as biphenyl, alkylbiphenyl, terphenyl, terphenyl, etc.
Aromatic compounds such as cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran;
Partially fluorinated products of the aromatic compounds such as 2-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene;
Fluorinated anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, 3,5-difluoroanisole;
Etc.

  Of these, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran are preferable. Two or more of these may be used in combination. When two or more types are used in combination, in particular, a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, biphenyl, alkylbiphenyl, terphenyl, terphenyl partially hydrogenated product, cyclohexylbenzene, t-butylbenzene The balance between overcharge prevention characteristics and high-temperature storage characteristics is obtained by using a combination selected from oxygen-free aromatic compounds such as t-amylbenzene and oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran. From the point of view, it is preferable.

  The ratio of the overcharge inhibitor in the non-aqueous electrolyte is usually 0.1% by mass or more, preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, most preferably with respect to the whole non-aqueous electrolyte. Preferably it is 0.5 mass% or more, and an upper limit is 5 mass% or less normally, Preferably it is 3 mass% or less, Most preferably, it is 2 mass% or less. When the concentration is lower than this lower limit, the effect of the overcharge inhibitor hardly appears. On the other hand, if the concentration is too high, battery characteristics such as high-temperature storage characteristics tend to deteriorate.

<1-4-4. Auxiliary>
Specific examples of the auxiliary agent include, for example,
Carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate;
Succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, phenylsuccinic anhydride, etc. Carboxylic acid anhydrides of
Spiro compounds such as 2,4,8,10-tetraoxaspiro [5.5] undecane and 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane; sulfolene, dimethylsulfone , Sulfur-containing compounds such as diphenylsulfone, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide;
Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide;
Examples thereof include hydrocarbon compounds such as heptane, octane, nonane, decane and cycloheptane, and fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene and benzotrifluoride.

  Two or more of these may be used in combination. The ratio of these auxiliaries in the non-aqueous electrolyte is usually 0.01% by mass or more, preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more with respect to the whole non-aqueous electrolyte. The upper limit is usually 5% by mass or less, preferably 3% by mass or less, and particularly preferably 1% by mass or less. By adding these auxiliaries, capacity maintenance characteristics and cycle characteristics after high temperature storage can be improved. When the concentration is lower than this lower limit, the effect of the auxiliary agent hardly appears. Conversely, if the concentration is too high, battery characteristics such as high-load discharge characteristics tend to deteriorate.

<1-5. Preparation of non-aqueous electrolyte>
The non-aqueous electrolyte solution in the present invention can be prepared by dissolving a lithium salt, a room temperature molten salt, a monofluorophosphate salt or a difluorophosphate salt, and if necessary, “other compounds”. . In preparing the non-aqueous electrolyte solution, each raw material is preferably dehydrated in advance in order to reduce the water content when the non-aqueous electrolyte solution is used. Usually, it is good to dehydrate to 50 ppm or less, preferably 30 ppm or less, particularly preferably 10 ppm or less. Moreover, you may implement dehydration, a deoxidation process, etc. after non-aqueous electrolyte solution preparation.

  The non-aqueous electrolyte solution of the present invention is suitable for use as an electrolyte solution for secondary batteries, for example, lithium secondary batteries, among non-aqueous electrolyte batteries. Hereinafter, a non-aqueous electrolyte battery using the non-aqueous electrolyte of the present invention will be described.

[2. Non-aqueous electrolyte battery]
The non-aqueous electrolyte battery of the present invention comprises a negative electrode and a positive electrode that can occlude and release ions, and the non-aqueous electrolyte of the present invention.

<2-1. Battery configuration>
The non-aqueous electrolyte battery of the present invention is the same as the conventionally known non-aqueous electrolyte battery except for the negative electrode and the non-aqueous electrolyte, and is usually impregnated with the non-aqueous electrolyte of the present invention. A positive electrode and a negative electrode are laminated via a porous film (separator), and these are housed in a case (exterior body). Therefore, the shape of the non-aqueous electrolyte battery of the present invention is not particularly limited, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

<2-2. Non-aqueous electrolyte>
As the non-aqueous electrolyte, the above-described non-aqueous electrolyte of the present invention is used. In addition, in the range which does not deviate from the meaning of this invention, it is also possible to mix and use other nonaqueous electrolyte solution with respect to the nonaqueous electrolyte solution of this invention.

<2-3. Negative electrode>
The negative electrode active material used for the negative electrode is described below. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. Specific examples thereof include carbonaceous materials, alloy-based materials, lithium-containing metal composite oxide materials, and the like.

<2-3-1. Carbonaceous material>
As a carbonaceous material used as a negative electrode active material,
(1) natural graphite,
(2) a carbonaceous material obtained by heat-treating an artificial carbonaceous material and an artificial graphite material at least once in the range of 400 to 3200 ° C .;
(3) a carbonaceous material in which the negative electrode active material layer is composed of at least two types of carbonaceous materials having different crystallinity and / or has an interface in contact with the different crystalline carbonaceous materials,
(4) a carbonaceous material in which the negative electrode active material layer is composed of carbonaceous materials having at least two or more different orientations and / or has an interface in contact with the carbonaceous materials having different orientations;
Is preferably a good balance between initial irreversible capacity and high current density charge / discharge characteristics. Moreover, the carbonaceous materials (1) to (4) may be used alone or in combination of two or more in any combination and ratio.

  Specific examples of the artificial carbonaceous material and the artificial graphite material of (2) above include natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, or those obtained by oxidizing these pitches, Needle coke, pitch coke and carbon materials partially graphitized thereof, furnace black, acetylene black, organic pyrolysis products such as pitch-based carbon fibers, carbonizable organic materials, and these carbides or carbonizable organic materials Examples thereof include solutions dissolved in low-molecular organic solvents such as benzene, toluene, xylene, quinoline, and n-hexane, and carbides thereof.

  Specific examples of the above carbonizable organic substances include coal tar pitch from soft pitch to hard pitch, or heavy coal-based oil such as dry distillation liquefied oil, normal pressure residual oil, reduced pressure residual DC. Heavy oils such as ethylene tar produced as a by-product during pyrolysis of heavy oils such as heavy oil, crude oil, naphtha, etc., and aromatic hydrocarbons such as acenaphthylene, decacyclene, anthracene, phenanthrene, and nitrogen atom-containing complexes such as phenazine and acridine Cyclic compounds, heterocyclic compounds containing sulfur atoms such as thiophene and bithiophene, polyphenylenes such as biphenyl and terphenyl, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, insolubilized products of these, nitrogen-containing polyacrylonitrile Organic polymers such as polypyrrole, organic polymers such as sulfur-containing polythiophene and polystyrene Natural polymers such as polysaccharides such as saccharose, cellulose, lignin, mannan, polygalacturonic acid, chitosan, saccharose, thermoplastic resins such as polyphenylene sulfide and polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, imide Examples thereof include thermosetting resins such as resins.

<2-3-2. Configuration, physical properties, preparation method of carbonaceous negative electrode>
Regarding the properties of the carbonaceous material, the negative electrode containing the carbonaceous material, the electrodeification method, the current collector, and the non-aqueous electrolyte battery, any one or more of (1) to (18) shown below It is desirable to satisfy

(1) X-ray parameters The d-value (interlayer distance) of the lattice plane (002 plane) obtained by X-ray diffraction by the Gakushin method of carbonaceous materials is preferably 0.335 nm or more. It is 360 nm or less, preferably 0.350 nm or less, and more preferably 0.345 nm or less. Further, the crystallite size (Lc) of the carbonaceous material obtained by X-ray diffraction by the Gakushin method is preferably 1.0 nm or more, and more preferably 1.5 nm or more.

(2) Ash content The ash content in the carbonaceous material is preferably 1% by mass or less, more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less, based on the total mass of the carbonaceous material. It is preferably 1 ppm or more.

  When the weight ratio of ash exceeds the above range, deterioration of battery performance due to reaction with the non-aqueous electrolyte during charge / discharge may not be negligible. On the other hand, if it falls below the above range, the production requires a lot of time, energy and equipment for preventing contamination, which may increase the cost.

(3) Volume-based average particle size The volume-based average particle size of the carbonaceous material is usually a volume-based average particle size (median diameter) determined by a laser diffraction / scattering method of 1 μm or more, preferably 3 μm or more, It is more preferably 5 μm or more, particularly preferably 7 μm or more, and usually 100 μm or less, preferably 50 μm or less, more preferably 40 μm or less, still more preferably 30 μm or less, and particularly preferably 25 μm or less.

  If the volume-based average particle size is below the above range, the irreversible capacity may increase, leading to loss of initial battery capacity. On the other hand, when the above range is exceeded, when an electrode is produced by coating, an uneven coating surface tends to be formed, which may be undesirable in the battery production process.

  The volume-based average particle size is measured by dispersing carbon powder in a 0.2% by weight aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and laser diffraction / scattering particle size distribution. This is carried out using a meter (LA-700 manufactured by Horiba, Ltd.). The median diameter determined by the measurement is defined as the volume-based average particle diameter of the carbonaceous material of the present invention.

(4) Raman R value, Raman half-value width As for the Raman R value of the carbonaceous material, a value measured by using an argon ion laser Raman spectrum method is usually 0.01 or more, preferably 0.03 or more, preferably 1 or more is more preferable, and it is usually 1.5 or less, preferably 1.2 or less, more preferably 1 or less, and particularly preferably 0.5 or less.

  When the Raman R value is below the above range, the crystallinity of the particle surface becomes too high, and there are cases where the number of sites where Li enters between layers decreases with charge / discharge. That is, charge acceptance may be reduced. In addition, when the negative electrode is densified by applying it to the current collector and then pressing it, the crystals are likely to be oriented in a direction parallel to the electrode plate, which may lead to a decrease in load characteristics. On the other hand, if it exceeds the above range, the crystallinity of the particle surface is lowered, the reactivity with the non-aqueous electrolyte is increased, and the efficiency may be lowered and the gas generation may be increased.

Further, the Raman half-width in the vicinity of 1580 cm ^{−1 of the} carbonaceous material is not particularly limited, but is usually 10 cm ⁻¹ or more, preferably 15 cm ⁻¹ or more, and usually 100 cm ⁻¹ or less, and 80 cm ⁻¹ or less. Preferably, 60 cm ⁻¹ or less is more preferable, and 40 cm ⁻¹ or less is particularly preferable.

  If the Raman half width is less than the above range, the crystallinity of the particle surface becomes too high, and there are cases where the number of sites where Li enters between layers decreases with charge and discharge. That is, charge acceptance may be reduced. In addition, when the negative electrode is densified by applying it to the current collector and then pressing it, the crystals are likely to be oriented in a direction parallel to the electrode plate, which may lead to a decrease in load characteristics. On the other hand, if it exceeds the above range, the crystallinity of the particle surface is lowered, the reactivity with the non-aqueous electrolyte is increased, and the efficiency may be lowered and the gas generation may be increased.

The measurement of the Raman spectrum, using a Raman spectrometer (manufactured by JASCO Corporation Raman spectrometer), the sample is naturally dropped into the measurement cell and filled, and while irradiating the sample surface in the cell with argon ion laser light, This is done by rotating the cell in a plane perpendicular to the laser beam. The resulting Raman spectrum, the intensity _{I A} of the peak _{P A} in the vicinity of 1580 cm ^-1, and measuring the intensity _{I B} of a peak _{P B} in the vicinity of 1360 cm ^-1, the intensity ratio _{R (R = I B / I} A) Is calculated. The Raman R value calculated by the measurement is defined as the Raman R value of the carbonaceous material of the present invention. Further, the half width of the peak P _A in the vicinity of 1580 cm ^-1 of the resulting Raman spectrum was measured, which is defined as the Raman half-value width of the carbonaceous material of the present invention.

Moreover, said Raman measurement conditions are as follows.
Argon ion laser wavelength: 514.5nm
・ Laser power on the sample: 15-25mW
・ Resolution: 10-20cm ^-1
Measurement range: 1100 cm ^{−1 to} 1730 cm ⁻¹
・ Raman R value, Raman half width analysis: background processing,
-Smoothing processing: Simple average, 5 points of convolution

(5) BET specific surface area As for the BET specific surface area of the carbonaceous material, the value of the specific surface area measured using the BET method is usually 0.1 m ² · g ⁻¹ or more, and 0.7 m ² · g ⁻¹ or more. Is preferably 1.0 m ² · g ⁻¹ or more, more preferably 1.5 m ² · g ⁻¹ or more, and usually 100 m ² · g ⁻¹ or less, and 25 m ² · g ⁻¹ or less. It is preferably 15 m ² · g ⁻¹ or less, more preferably 10 m ² · g ⁻¹ or less.

  When the value of the BET specific surface area is less than this range, the acceptability of lithium is likely to deteriorate during charging when used as a negative electrode material, lithium is likely to precipitate on the electrode surface, and stability may be reduced. On the other hand, if it exceeds this range, when used as a negative electrode material, the reactivity with the non-aqueous electrolyte increases, gas generation tends to increase, and a preferable battery may be difficult to obtain.

  The specific surface area was measured by the BET method using a surface area meter (a fully automated surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 350 ° C. for 15 minutes under nitrogen flow, Using a nitrogen helium mixed gas accurately adjusted so that the value of the relative pressure becomes 0.3, the nitrogen adsorption BET one-point method by the gas flow method is used. The specific surface area determined by the measurement is defined as the BET specific surface area of the carbonaceous material of the present invention.

(6) Pore size distribution The pore size distribution of the carbonaceous material is calculated by measuring the mercury intrusion amount. By using mercury porosimetry (mercury intrusion method), fine pores with a diameter of 0.01 μm or more and 1 μm or less with voids in particles of carbonaceous material, irregularities due to steps on the particle surface, and contact surfaces between particles, etc. carbonaceous material to be measured to correspond to the holes, usually 0.01 cm ³ · ^{g -1} or more, preferably 0.05 cm ³ · ^{g -1} or more, more preferably 0.1 cm ³ · ^{g -1} or more, It is usually desirable to have a pore size distribution of 0.6 cm ³ · g ⁻¹ or less, preferably 0.4 cm ³ · g ⁻¹ or less, more preferably 0.3 cm ³ · g ⁻¹ or less.

  If the pore size distribution exceeds the above range, a large amount of binder may be required when forming an electrode plate. On the other hand, if it falls below the above range, the high current density charge / discharge characteristics may be deteriorated, and the effect of relaxing the expansion and contraction of the electrode during charge / discharge may not be obtained.

Further, the total pore volume, which is obtained by mercury porosimetry (mercury intrusion method) and corresponds to pores having a diameter of 0.01 μm or more and 100 μm or less, is usually 0.1 cm ³ · g ⁻¹ or more, and 25 cm ³ · ^{g -1} or more, more preferably 0.4 cm ³ · ^{g -1} or higher, and is generally 10 cm ³ · ^{g -1} or less, preferably ^{5 cm} 3 · ^{g -1} or less, ^{2 cm} 3 · g ^-1 or less is more preferable. If the total pore volume exceeds the above range, a large amount of binder may be required when forming an electrode plate. On the other hand, if the amount is below the above range, the effect of dispersing the thickener or the binder may not be obtained when forming the electrode plate.

  The average pore diameter is usually 0.05 μm or more, preferably 0.1 μm or more, more preferably 0.5 μm or more, and usually 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less. If the average pore diameter exceeds the above range, a large amount of binder may be required. Moreover, when it is less than the above range, the high current density charge / discharge characteristics may deteriorate.

  The mercury intrusion is measured using a mercury porosimeter (Autopore 9520: manufactured by Micromeritex Corporation) as an apparatus for mercury porosimetry. As a pretreatment, about 0.2 g of a sample is sealed in a powder cell and deaerated for 10 minutes at room temperature under vacuum (50 μmHg or less). Subsequently, the pressure is reduced to 4 psia (about 28 kPa), mercury is introduced, the pressure is increased stepwise from 4 psia (about 28 kPa) to 40000 psia (about 280 MPa), and then the pressure is reduced to 25 psia (about 170 kPa). The number of steps at the time of pressure increase is 80 points or more, and the mercury intrusion amount is measured after an equilibration time of 10 seconds in each step.

The pore size distribution is calculated from the mercury intrusion curve thus obtained using the Washburn equation. Note that the surface tension (γ) of mercury is 485 dyne · cm ⁻¹ ( ¹ dyne = 10 μN), and the contact angle (ψ) is 140 °. As the average pore diameter, the pore diameter when the cumulative pore volume is 50% is used.

(7) Circularity When the circularity is measured as a spherical degree of the carbonaceous material, it is preferably within the following range. The circularity is defined as “circularity = (peripheral length of an equivalent circle having the same area as the particle projection shape) / (actual perimeter of the particle projection shape)”, and is theoretical when the circularity is 1. Become a true sphere.

  The circularity of the particles having a particle size of 3 to 40 μm in the range of the carbonaceous material is desirably closer to 1, and is preferably 0.1 or more, more preferably 0.5 or more, and more preferably 0.8 or more, 0.85 or more is more preferable, and 0.9 or more is particularly preferable. High current density charge / discharge characteristics improve as the degree of circularity increases. Therefore, when the circularity is less than the above range, the filling property of the negative electrode active material is lowered, the resistance between particles is increased, and the high current density charge / discharge characteristics may be lowered for a short time.

  The circularity is measured using a flow type particle image analyzer (FPIA manufactured by Sysmex Corporation). About 0.2 g of a sample was dispersed in a 0.2% by mass aqueous solution (about 50 mL) of polyoxyethylene (20) sorbitan monolaurate as a surfactant, and irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute. The detection range is specified as 0.6 to 400 μm, and the particle size is measured in the range of 3 to 40 μm. The circularity determined by the measurement is defined as the circularity of the carbonaceous material of the present invention.

  The method for improving the degree of circularity is not particularly limited, but a spheroidized sphere is preferable because the shape of the interparticle void when the electrode body is formed is preferable. Examples of spheroidizing treatment include a method of mechanically approximating a sphere by applying a shearing force and a compressive force, a mechanical / physical processing method of granulating a plurality of fine particles by an adhesive force possessed by a binder or particles, etc. Is mentioned.

True density of (8) True Density carbonaceous material is usually 1.4 g · ^{cm -3} or higher, preferably 1.6 g · ^{cm -3} or more, more preferably 1.8 g · ^{cm -3} or more, 2. 0 g · ^{cm -3} or more are particularly preferred, also, usually less than 2.26 g · ^{cm -3.} When the true density is below the above range, the crystallinity of carbon is too low, and the initial irreversible capacity may increase. The upper limit of the above range is the theoretical upper limit of the true density of graphite.

  The true density of the carbonaceous material is measured by a liquid phase substitution method (pycnometer method) using butanol. The value obtained by the measurement is defined as the true density of the carbonaceous material of the present invention.

(9) Tap density The tap density of the carbonaceous material is usually 0.1 g · cm ⁻³ or more, preferably 0.5 g · cm ⁻³ or more, more preferably 0.7 g · cm ⁻³ or more, and 1 g · cm ⁻³ or more is particularly preferable, 2 g · cm ⁻³ or less is preferable, 1.8 g · cm ⁻³ or less is more preferable, and 1.6 g · cm ⁻³ or less is particularly preferable. When the tap density is below the above range, the packing density is difficult to increase when used as a negative electrode, and a high-capacity battery may not be obtained. On the other hand, when the above range is exceeded, there are too few voids between particles in the electrode, it is difficult to ensure conductivity between the particles, and it may be difficult to obtain preferable battery characteristics.

The tap density is measured by passing through a sieve having an opening of 300 μm, dropping the sample onto a 20 cm ³ tapping cell and filling the sample to the upper end surface of the cell, and then measuring a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Using a tap denser, tapping with a stroke length of 10 mm is performed 1000 times, and the tap density is calculated from the volume at that time and the weight of the sample. The tap density calculated by the measurement is defined as the tap density of the carbonaceous material of the present invention.

(10) Orientation ratio The orientation ratio of the carbonaceous material is usually 0.005 or more, preferably 0.01 or more, more preferably 0.015 or more, and usually 0.67 or less. When the orientation ratio is below the above range, the high-density charge / discharge characteristics may deteriorate. The upper limit of the above range is the theoretical upper limit value of the orientation ratio of the carbonaceous material.

The orientation ratio is measured by X-ray diffraction after pressure-molding the sample. Set the molding obtained by filling 0.47 g of the sample into a molding machine with a diameter of 17 mm and compressing it with 58.8 MN · m ^{-2 so} that it is flush with the surface of the sample holder for measurement. X-ray diffraction is measured. From the (110) diffraction and (004) diffraction peak intensities of the obtained carbon, a ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated. The orientation ratio calculated by the measurement is defined as the orientation ratio of the carbonaceous material of the present invention.

The X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Divergence slit = 0.5 degree Light receiving slit = 0.15 mm
Scattering slit = 0.5 degree / measurement range and step angle / measurement time:
(110) plane: 75 degrees ≦ 2θ ≦ 80 degrees 1 degree / 60 seconds (004) plane: 52 degrees ≦ 2θ ≦ 57 degrees 1 degree / 60 seconds

(11) Aspect ratio (powder)
The aspect ratio of the carbonaceous material is usually 1 or more and usually 10 or less, preferably 8 or less, and more preferably 5 or less. If the aspect ratio exceeds the above range, streaking or a uniform coated surface cannot be obtained when forming an electrode plate, and the high current density charge / discharge characteristics may deteriorate. The lower limit of the above range is the theoretical lower limit value of the aspect ratio of the carbonaceous material.

  The aspect ratio is measured by magnifying and observing the carbonaceous material particles with a scanning electron microscope. Carbonaceous material particles when three-dimensional observation is performed by selecting arbitrary 50 graphite particles fixed to the end face of a metal having a thickness of 50 μm or less and rotating and tilting the stage on which the sample is fixed. The longest diameter A and the shortest diameter B orthogonal thereto are measured, and the average value of A / B is obtained. The aspect ratio (A / B) obtained by the measurement is defined as the aspect ratio of the carbonaceous material of the present invention.

(12) Secondary material mixing The secondary material mixing means that two or more carbonaceous materials having different properties are contained in the negative electrode and / or the negative electrode active material. The properties referred to here are selected from the group consisting of X-ray diffraction parameters, median diameter, aspect ratio, BET specific surface area, orientation ratio, Raman R value, tap density, true density, pore distribution, circularity, and ash content. Shows more than one characteristic.

  Particularly preferable examples of these secondary material mixtures include that the volume-based particle size distribution is not symmetrical when centered on the median diameter, contains two or more carbonaceous materials having different Raman R values, and The X-ray parameters are different.

  As an example of the effect of the auxiliary material mixing, carbonaceous materials such as graphite (natural graphite, artificial graphite and the like), carbon black such as acetylene black, and amorphous carbon such as needle coke are contained as a conductive material. Reducing electrical resistance.

  When mixing a conductive material as a secondary material mixture, one type may be mixed alone, or two or more types may be mixed in any combination and ratio. The mixing ratio of the conductive material to the carbonaceous material is usually preferably 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 45% by mass or less. 40% by mass is preferred. If the mixing ratio is less than the above range, it may be difficult to obtain the effect of improving conductivity. On the other hand, exceeding the above range may increase the initial irreversible capacity.

(13) Electrode production Any known method can be used for producing an electrode as long as the effects of the present invention are not significantly limited. For example, it is formed by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, etc. to a negative electrode active material to form a slurry, which is applied to a current collector, dried and then pressed. Can do.

  The thickness of the negative electrode active material layer per side in the stage immediately before the non-aqueous electrolyte injection process of the battery is usually 15 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and usually 150 μm or less. 120 μm or less is preferable, and 100 μm or less is more preferable. This is because if the thickness of the negative electrode active material exceeds this range, the non-aqueous electrolyte solution hardly penetrates to the vicinity of the current collector interface, and thus the high current density charge / discharge characteristics may be deteriorated. Further, if the ratio is below this range, the volume ratio of the current collector to the negative electrode active material increases, and the battery capacity may decrease. Further, the negative electrode active material may be roll-formed to form a sheet electrode, or may be formed into a pellet electrode by compression molding.

(14) Current collector As the current collector for holding the negative electrode active material, a known material can be arbitrarily used. Examples of the current collector for the negative electrode include metal materials such as copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable from the viewpoint of ease of processing and cost.

  In addition, the shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, or the like when the current collector is a metal material. Among them, a metal thin film is preferable, and a copper foil is more preferable, and a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method are more preferable, and both can be used as a current collector.

  In addition, when the thickness of the copper foil is less than 25 μm, a copper alloy (phosphor bronze, titanium copper, Corson alloy, Cu—Cr—Zr alloy, etc.) having higher strength than pure copper can be used. A current collector made of a copper foil produced by a rolling method is suitable for use in a small cylindrical battery because the copper crystals are arranged in the rolling direction so that the negative electrode is hard to crack even if it is rounded sharply or rounded at an acute angle. be able to.

  For example, an electrolytic copper foil is prepared by immersing a metal drum in an electrolytic solution in which copper ions are dissolved, and flowing current while rotating the copper drum, thereby depositing copper on the surface of the drum and peeling it off. It is obtained. Copper may be deposited on the surface of the rolled copper foil by an electrolytic method. One side or both sides of the copper foil may be subjected to a roughening treatment or a surface treatment (for example, a chromate treatment having a thickness of about several nm to 1 μm, a base treatment such as Ti).

  The following physical properties are desired for the current collector substrate.

(14-1) Average surface roughness (Ra)
The average surface roughness (Ra) of the negative electrode active material thin film forming surface of the current collector substrate defined by the method described in JIS B0601-1994 is not particularly limited, but is usually 0.05 μm or more and 0.1 μm or more. Preferably, it is more preferably 0.15 μm or more, and is usually 1.5 μm or less, preferably 1.3 μm or less, more preferably 1.0 μm or less. This is because when the average surface roughness (Ra) of the current collector substrate is within the above range, good charge / discharge cycle characteristics can be expected. Further, the area of the interface with the negative electrode active material thin film is increased, and the adhesion with the negative electrode active material thin film is improved. The upper limit value of the average surface roughness (Ra) is not particularly limited, but those having an average surface roughness (Ra) exceeding 1.5 μm are generally available as foils having a practical thickness as a battery. Since it is difficult, those of 1.5 μm or less are usually used.

(14-2) Tensile strength The tensile strength is obtained by dividing the maximum tensile force required until the test piece breaks by the cross-sectional area of the test piece. The tensile strength in the present invention is measured by the same apparatus and method as described in JISZ2241 (metal material tensile test method).

The tensile strength of the current collector substrate is not particularly limited, is usually 100 N · ^{mm -2} or more, preferably 250 N · ^{mm -2} or more, more preferably 400 N · ^{mm -2} or more, 500 N · ^{mm -2} or more Particularly preferred. The tensile strength is preferably as high as possible, but is usually 1000 N · mm ⁻² or less from the viewpoint of industrial availability. If the current collector substrate has a high tensile strength, cracking of the current collector substrate due to expansion / contraction of the negative electrode active material thin film accompanying charging / discharging can be suppressed, and good cycle characteristics can be obtained.

(14-3) 0.2% proof stress 0.2% proof stress is the magnitude of a load required to give a plastic (permanent) strain of 0.2%. It means that 0.2% deformation has occurred even when loaded. The 0.2% yield strength is measured with the same equipment and method as the tensile strength.

0.2% proof stress of the current collector substrate is not particularly limited, normally 30 N · ^{mm -2} or more, preferably 150 N · ^{mm -2} or more, particularly preferably 300N · ^{mm -2} or more. The 0.2% resistance value is preferably as high as possible, but 900 N · mm ⁻² or less is usually desirable from the viewpoint of industrial availability. If the current collector substrate has a high 0.2% proof stress, plastic deformation of the current collector substrate due to expansion / contraction of the negative electrode active material thin film accompanying charging / discharging can be suppressed, and good cycle characteristics can be obtained. Can do.

(14-4) Thickness of current collector Although the thickness of the current collector is arbitrary, it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, 100 μm or less. Is preferably 50 μm or less. When the thickness of the current collector is thinner than 1 μm, the strength may be reduced, which may make application difficult. Moreover, when it becomes thicker than 100 micrometers, the shape of electrodes, such as winding, may be changed. The current collector may be mesh.

(15) Ratio of thickness of current collector and negative electrode active material layer The ratio of the thickness of current collector and negative electrode active material layer is not particularly limited. The value of “material layer thickness) / (current collector thickness)” is preferably 150 or less, more preferably 20 or less, particularly preferably 10 or less, more preferably 0.1 or more, and 0.4 or more. More preferred is 1 or more. When the ratio of the thickness of the current collector to the negative electrode active material layer exceeds the above range, the current collector may generate heat due to Joule heat during high current density charge / discharge. On the other hand, below the above range, the volume ratio of the current collector to the negative electrode active material increases, and the battery capacity may decrease.

(16) Electrode density The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, but the density of the negative electrode active material present on the current collector is preferably 1 g · cm ⁻³ or more. 2 g · cm ⁻³ or more is more preferable, 1.3 g · cm ⁻³ or more is particularly preferable, 2 g · cm ⁻³ or less is preferable, 1.9 g · cm ⁻³ or less is more preferable, and 1.8 g · cm. ⁻³ or less is more preferable, and 1.7 g · cm ⁻³ or less is particularly preferable. When the density of the negative electrode active material existing on the current collector exceeds the above range, the negative electrode active material particles are destroyed, and the initial irreversible capacity increases or non-aqueous system near the current collector / negative electrode active material interface. There is a case where high current density charge / discharge characteristics are deteriorated due to a decrease in permeability of the electrolytic solution. On the other hand, if the amount is less than the above range, the conductivity between the negative electrode active materials decreases, the battery resistance increases, and the capacity per unit volume may decrease.

(17) Binder The binder for binding the negative electrode active material is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte and the solvent used during electrode production.

  Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, NBR ( Acrylonitrile / butadiene rubber), rubbery polymers such as ethylene / propylene rubber; styrene / butadiene / styrene block copolymers or hydrogenated products thereof; EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / Thermoplastic elastomeric polymer such as butadiene / styrene copolymer, styrene / isoprene / styrene block copolymer or hydrogenated product thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene Soft resinous polymers such as vinyl acetate copolymer and propylene / α-olefin copolymer; Fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene / ethylene copolymer Polymers: Polymer compositions having ionic conductivity of alkali metal ions (particularly lithium ions), and the like. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  The solvent for forming the slurry is not particularly limited as long as it is a solvent capable of dissolving or dispersing the negative electrode active material, the binder, and the thickener and conductive material used as necessary. Alternatively, either an aqueous solvent or an organic solvent may be used.

  Examples of the aqueous solvent include water, alcohol and the like, and examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N , N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like.

  In particular, when an aqueous solvent is used, it is preferable to add a dispersant or the like in addition to the thickener and slurry it using a latex such as SBR. In addition, these solvents may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, and preferably 20% by mass or less, 15% by mass. The following is more preferable, 10 mass% or less is still more preferable, and 8 mass% or less is especially preferable. When the ratio of the binder with respect to a negative electrode active material exceeds the said range, the binder ratio from which the amount of binders does not contribute to battery capacity may increase, and the fall of battery capacity may be caused. On the other hand, below the above range, the strength of the negative electrode may be reduced.

  In particular, when a rubbery polymer typified by SBR is contained as a main component, the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, and 0 .6% by mass or more is more preferable, and is usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. Moreover, when the main component contains a fluorine-based polymer typified by polyvinylidene fluoride, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more. Preferably, it is usually 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

  A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  Furthermore, when using a thickener, the ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, Moreover, it is 5 mass% or less normally, 3 mass% or less is preferable, and 2 mass% or less is still more preferable. When the ratio of the thickener to the negative electrode active material is less than the above range, applicability may be significantly reduced. Moreover, when it exceeds the said range, the ratio of the negative electrode active material which occupies for a negative electrode active material layer will fall, and the problem that the capacity | capacitance of a battery falls and the resistance between negative electrode active materials may increase.

(18) Electrode orientation ratio The electrode orientation ratio is usually 0.001 or more, preferably 0.005 or more, more preferably 0.01 or more, and usually 0.67 or less. When the electrode plate orientation ratio is below the above range, the high-density charge / discharge characteristics may be deteriorated. The upper limit of the above range is the theoretical upper limit of the electrode plate orientation ratio of the carbonaceous material.

  The electrode plate orientation ratio is measured by measuring the orientation ratio of the negative electrode active material of the electrode by X-ray diffraction for the negative electrode after being pressed to the target density. The specific method is not particularly limited. As a standard method, peak separation is performed by fitting peaks of carbon (110) diffraction and (004) diffraction by X-ray diffraction using asymmetric Pearson VII as a profile function. The integrated intensities of the peaks of (110) diffraction and (004) diffraction are calculated. From the obtained integrated intensity, a ratio represented by (110) diffraction integrated intensity / (004) diffraction integrated intensity is calculated. The electrode negative electrode active material orientation ratio calculated by the measurement is defined as the electrode plate orientation ratio of the carbonaceous material of the present invention.

The X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
-Target: Cu (Kα ray) graphite monochromator-Slit: Divergence slit = 1 degree, Receiving slit = 0.1 mm, Scattering slit = 1 degree-Measurement range and step angle / measurement time:
(110) plane: 76.5 degrees ≦ 2θ ≦ 78.5 degrees 0.01 degrees / 3 seconds (004) plane: 53.5 degrees ≦ 2θ ≦ 56.0 degrees 0.01 degrees / 3 seconds Sample preparation: Fix the electrode to the glass plate with double-sided tape with a thickness of 0.1 mm

<2-3-3. Structure, physical properties, and preparation method of negative electrode using metal compound material and metal compound material>
As the metal compound-based material used as the negative electrode active material, if lithium can be occluded / released, a single metal or alloy that forms a lithium alloy, or an oxide, carbide, nitride, silicide, sulfide, Any compound such as phosphide is not particularly limited. Examples of such metal compounds include compounds containing metals such as Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn, Sr, and Zn. Among these, a single metal or an alloy that forms a lithium alloy is preferable, and a material containing a group 13 or group 14 metal / metalloid element (that is, excluding carbon) is more preferable. Further, silicon (Si ), Tin (Sn) or lead (Pb) (hereinafter, these three elements may be referred to as “specific metal elements”), simple metals, alloys containing these atoms, or their metals (specific metal elements) It is preferable that it is a compound of these. These may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Examples of the negative electrode active material having at least one kind of atom selected from the specific metal element include a single metal of any one specific metal element, an alloy composed of two or more specific metal elements, one type, or two or more types Alloys composed of specific metal elements and other one or more metal elements, compounds containing one or more specific metal elements, and oxides, carbides, nitrides, and the like of the compounds Examples include composite compounds such as silicides, sulfides, and phosphides. By using these simple metals, alloys or metal compounds as the negative electrode active material, the capacity of the battery can be increased.

  Moreover, the compound which these complex compounds combined with several elements, such as a metal simple substance, an alloy, or a nonmetallic element, can also be mentioned as an example. More specifically, for example, in silicon and tin, an alloy of these elements and a metal that does not operate as a negative electrode can be used. For example, in the case of tin, a complex compound containing 5 to 6 kinds of elements in combination with a metal that acts as a negative electrode other than tin and silicon, a metal that does not operate as a negative electrode, and a nonmetallic element can also be used. .

  Among these negative electrode active materials, since the capacity per unit weight is large when a battery is formed, any one metal element of a specific metal element, an alloy of two or more specific metal elements, oxidation of a specific metal element In particular, silicon and / or tin metal simple substance, alloy, oxide, carbide, nitride and the like are preferable from the viewpoint of capacity per unit weight and environmental load.

In addition, although the capacity per unit weight is inferior to that of a single metal or an alloy, the following compounds containing silicon and / or tin are also preferable because of excellent cycle characteristics.
The element ratio of silicon and / or tin to oxygen is usually 0.5 or more, preferably 0.7 or more, more preferably 0.9 or more, and usually 1.5 or less, preferably 1. Silicon and / or tin oxide of 3 or less, more preferably 1.1 or less.
-Element ratio of silicon and / or tin and nitrogen is usually 0.5 or more, preferably 0.7 or more, more preferably 0.9 or more, and usually 1.5 or less, preferably 1. Silicon and / or tin nitride of 3 or less, more preferably 1.1 or less.
The elemental ratio of silicon and / or tin to carbon is usually 0.5 or more, preferably 0.7 or more, more preferably 0.9 or more, and usually 1.5 or less, preferably 1. Silicon and / or tin carbide of 3 or less, more preferably 1.1 or less.

  In addition, any one of the above-described negative electrode active materials may be used alone, or two or more thereof may be used in any combination and ratio.

  The negative electrode in the non-aqueous electrolyte battery of the present invention can be manufactured using any known method. Specifically, as a manufacturing method of the negative electrode, for example, a method in which a negative electrode active material added with a binder or a conductive material is roll-formed as it is to form a sheet electrode, or a compression-molded pellet electrode and The above negative electrode is usually applied to a negative electrode current collector (hereinafter also referred to as “negative electrode current collector”) by a method such as a coating method, a vapor deposition method, a sputtering method, or a plating method. A method of forming a thin film layer (negative electrode active material layer) containing an active material is used. In this case, by adding a binder, a thickener, a conductive material, a solvent, etc. to the above-mentioned negative electrode active material to form a slurry, applying this to the negative electrode current collector, drying, and pressing to increase the density A negative electrode active material layer is formed on the negative electrode current collector.

  Examples of the material of the negative electrode current collector include steel, copper alloy, nickel, nickel alloy, and stainless steel. Of these, copper foil is preferred from the viewpoint of easy processing into a thin film and cost.

  The thickness of the negative electrode current collector is usually 1 μm or more, preferably 5 μm or more, and is usually 100 μm or less, preferably 50 μm or less. This is because if the thickness of the negative electrode current collector is too thick, the capacity of the entire battery may be too low, and conversely if it is too thin, handling may be difficult.

  In addition, in order to improve the binding effect with the negative electrode active material layer formed on the surface, the surface of these negative electrode current collectors is preferably subjected to a roughening treatment in advance. Surface roughening methods include blasting, rolling with a rough surface roll, polishing cloth with a fixed abrasive particle, grinding wheel, emery buff, machine that polishes the current collector surface with a wire brush equipped with steel wire, etc. Examples thereof include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method.

  Further, in order to reduce the weight of the negative electrode current collector and improve the energy density per weight of the battery, a perforated negative electrode current collector such as an expanded metal or a punching metal can be used. This type of negative electrode current collector can be freely changed in weight by changing its aperture ratio. Further, when a negative electrode active material layer is formed on both surfaces of this type of negative electrode current collector, the negative electrode active material layer is further less likely to peel due to the rivet effect through the hole. However, when the aperture ratio becomes too high, the contact area between the negative electrode active material layer and the negative electrode current collector becomes small, and thus the adhesive strength may be lowered.

  The slurry for forming the negative electrode active material layer is usually prepared by adding a binder, a thickener and the like to the negative electrode material. In addition, the “negative electrode material” in this specification refers to a material in which a negative electrode active material and a conductive material are combined.

  The content of the negative electrode active material in the negative electrode material is usually 70% by mass or more, particularly 75% by mass or more, and usually 97% by mass or less, and particularly preferably 95% by mass or less. If the content of the negative electrode active material is too small, the capacity of the non-aqueous electrolyte battery using the obtained negative electrode tends to be insufficient, and if it is too large, the content of the binder and the like is relatively insufficient. This is because the strength of the obtained negative electrode tends to be insufficient. When two or more negative electrode active materials are used in combination, the total amount of the negative electrode active materials may be set to satisfy the above range.

  Examples of the conductive material used for the negative electrode include metal materials such as copper and nickel; carbon materials such as graphite and carbon black. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. In particular, it is preferable to use a carbon material as the conductive material because the carbon material acts as an active material. It is preferable that the content of the conductive material in the negative electrode material is usually 3% by mass or more, particularly 5% by mass or more, and usually 30% by mass or less, particularly 25% by mass or less. When the content of the conductive material is too small, the conductivity tends to be insufficient. When the content is too large, the content of the negative electrode active material or the like is relatively insufficient, which tends to decrease the battery capacity and strength. . Note that when two or more conductive materials are used in combination, the total amount of the conductive materials may satisfy the above range.

  As the binder used for the negative electrode, any material can be used as long as it is a safe material with respect to the solvent and non-aqueous electrolyte used in manufacturing the electrode. Examples thereof include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene / butadiene rubber / isoprene rubber, butadiene rubber, ethylene-acrylic acid copolymer, and ethylene / methacrylic acid copolymer. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. The content of the binder is usually 0.5 parts by weight or more, particularly 1 part by weight or more, and usually 10 parts by weight or less, particularly 8 parts by weight or less, with respect to 100 parts by weight of the negative electrode material. When the content of the binder is too small, the strength of the obtained negative electrode tends to be insufficient. When the content is too large, the content of the negative electrode active material and the like is relatively insufficient, and thus the battery capacity and conductivity tend to be insufficient. It is because it becomes. In addition, when using two or more binders together, what is necessary is just to make it the total amount of a binder satisfy | fill the said range.

  Examples of the thickener used for the negative electrode include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. The thickener may be used as necessary, but when used, the thickener content in the negative electrode active material layer is usually in the range of 0.5 mass% or more and 5 mass% or less. Is preferred.

  The slurry for forming the negative electrode active material layer is prepared by mixing the negative electrode active material with a conductive material, a binder, or a thickener as necessary, and using an aqueous solvent or an organic solvent as a dispersion medium. . As the aqueous solvent, water is usually used, but a solvent other than water such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone is used in combination at a ratio of about 30% by mass or less with respect to water. You can also As the organic solvent, usually, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic carbonization such as anisole, toluene and xylene Examples thereof include alcohols such as hydrogens, butanol and cyclohexanol, among which cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide are preferable. . Any one of these may be used alone, or two or more may be used in any combination and ratio.

  The viscosity of the slurry is not particularly limited as long as it is a viscosity that can be applied onto the current collector. What is necessary is just to prepare suitably by changing the usage-amount of a solvent etc. at the time of preparation of a slurry so that it may become the viscosity which can be apply | coated.

  The obtained slurry is applied onto the above-described negative electrode current collector, dried, and then pressed to form a negative electrode active material layer. The method of application is not particularly limited, and a method known per se can be used. The drying method is not particularly limited, and a known method such as natural drying, heat drying, or reduced pressure drying can be used.

The electrode structure when the negative electrode active material is made into an electrode by the above method is not particularly limited, but the density of the active material present on the current collector is preferably 1 g · cm ⁻³ or more, and 1.2 g · cm ⁻³ or more is more preferable, 1.3 g · cm ⁻³ or more is particularly preferable, 2 g · cm ⁻³ or less is preferable, 1.9 g · cm ⁻³ or less is more preferable, and 1.8 g · cm ⁻³ or less. Is more preferable, and 1.7 g · cm ⁻³ or less is particularly preferable.

  When the density of the active material existing on the current collector exceeds the above range, the active material particles are destroyed, the initial irreversible capacity increases, and the non-aqueous electrolyte solution near the current collector / active material interface There is a case where high current density charge / discharge characteristics are deteriorated due to a decrease in permeability. On the other hand, below the above range, the conductivity between the active materials may be reduced, the battery resistance may be increased, and the capacity per unit volume may be reduced.

<2-3-4. Lithium-containing metal composite oxide material, and negative electrode configuration, physical properties, and preparation method using lithium-containing metal composite oxide material>
The lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can occlude and release lithium, but a lithium-containing composite metal oxide material containing titanium is preferable. An oxide (hereinafter abbreviated as “lithium titanium composite oxide”) is particularly preferable. That is, it is particularly preferable to use a lithium titanium composite oxide having a spinel structure in a negative electrode active material for a non-aqueous electrolyte battery because the output resistance is greatly reduced.

  In addition, lithium or titanium of the lithium titanium composite oxide is at least selected from the group consisting of other metal elements such as Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. Those substituted with one element are also preferred.

  The metal oxide is a lithium titanium composite oxide represented by the general formula (16). In the general formula (16), 0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, It is preferable that 0 ≦ z ≦ 1.6 because the structure upon doping and dedoping of lithium ions is stable.

_{Li x Ti y M z O 4} (16)
[In General Formula (16), M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. ]

Among the compositions represented by the general formula (16),
(A) 1.2 ≦ x ≦ 1.4, 1.5 ≦ y ≦ 1.7, z = 0
(B) 0.9 ≦ x ≦ 1.1, 1.9 ≦ y ≦ 2.1, z = 0
(C) 0.7 ≦ x ≦ 0.9, 2.1 ≦ y ≦ 2.3, z = 0
This structure is particularly preferable because of a good balance of battery performance.

Particularly preferred representative compositions of the above compounds are Li _4/3 Ti _5/3 O ₄ in (a), Li ₁ Ti ₂ O ₄ in (b), and Li _4/5 Ti _11/5 O in (c). ₄ . As for the structure of Z ≠ 0, for example, Li _4/3 Ti _4/3 Al _{1 / 3O 4} is preferable.

  In addition to the above requirements, the lithium titanium composite oxide as the negative electrode active material in the present invention further satisfies at least one of the characteristics such as physical properties and shapes shown in the following (1) to (13). It is preferable to satisfy two or more at the same time.

(1) BET specific surface area As for the BET specific surface area of the lithium titanium composite oxide used as the negative electrode active material, the specific surface area value measured using the BET method is preferably 0.5 m ² · g ⁻¹ or more. 7 m ² · g ⁻¹ or more is more preferred, 1.0 m ² · g ⁻¹ or more is more preferred, 1.5 m ² · g ⁻¹ or more is particularly preferred, and 200 m ² · g ⁻¹ or less is preferred, 100 m ² · g ⁻¹ or less is more preferred, 50 m ² · g ⁻¹ or less is more preferred, and 25 m ² · g ⁻¹ or less is particularly preferred.

  When the BET specific surface area is less than the above range, the reaction area in contact with the non-aqueous electrolyte when used as the negative electrode material may decrease, and the output resistance may increase. On the other hand, if it exceeds the above range, the surface of the metal oxide crystal containing titanium and the portion of the end face increase, and due to this, crystal distortion also occurs, irreversible capacity cannot be ignored, which is preferable It may be difficult to obtain a battery.

  The specific surface area was measured by the BET method using a surface area meter (a fully automated surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 350 ° C. for 15 minutes under nitrogen flow, Using a nitrogen helium mixed gas accurately adjusted so that the value of the relative pressure becomes 0.3, the nitrogen adsorption BET one-point method by the gas flow method is used. The specific surface area determined by the measurement is defined as the BET specific surface area of the lithium titanium composite oxide of the present invention.

(2) Volume-based average particle diameter The volume-based average particle diameter of lithium-titanium composite oxide (secondary particle diameter when primary particles are aggregated to form secondary particles) is determined by laser diffraction / scattering method. It is defined by the obtained volume-based average particle diameter (median diameter).

  The volume-based average particle size of the lithium titanium composite oxide is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 0.7 μm or more, and usually 50 μm or less, preferably 40 μm or less, 30 μm. The following is more preferable, and 25 μm or less is particularly preferable.

  The volume-based average particle size is measured by dispersing a carbon powder in a 0.2% by mass aqueous solution (10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and a laser diffraction / scattering particle size distribution analyzer. (LA-700 manufactured by Horiba Ltd.) is used. The median diameter determined by the measurement is defined as the volume-based average particle diameter of the carbonaceous material of the present invention.

  When the volume average particle size of the lithium titanium composite oxide is below the above range, a large amount of binder is required at the time of producing the electrode, and as a result, the battery capacity may decrease. On the other hand, if it exceeds the above range, an uneven coating surface tends to be formed when forming an electrode plate, which may be undesirable in the battery manufacturing process.

(3) Average primary particle diameter When primary particles are aggregated to form secondary particles, the average primary particle diameter of the lithium titanium composite oxide is usually 0.01 μm or more, and 0.05 μm or more. Preferably, it is 0.1 μm or more, more preferably 0.2 μm or more, and usually 2 μm or less, preferably 1.6 μm or less, more preferably 1.3 μm or less, and particularly preferably 1 μm or less. When the volume-based average primary particle diameter exceeds the above range, it is difficult to form spherical secondary particles, which adversely affects the powder filling property and the specific surface area greatly decreases. There is a possibility that performance is likely to deteriorate. On the other hand, below the above range, there are cases where the performance of the secondary battery is lowered, for example, reversibility of charge / discharge is inferior because crystals are underdeveloped.

  The primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification at which particles can be confirmed, for example, a magnification of 10,000 to 100,000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is determined for any 50 primary particles. Obtained and obtained by taking an average value.

(4) Shape As the shape of the lithium titanium composite oxide particles, a lump shape, a polyhedron shape, a sphere shape, an oval sphere shape, a plate shape, a needle shape, a column shape, etc., which are conventionally used, are used. Thus, it is preferable to form secondary particles, and the shape of the secondary particles is spherical or elliptical.

  In general, an electrochemical element expands and contracts as the active material in the electrode expands and contracts as it is charged and discharged. Therefore, the active material is easily damaged due to the stress or the conductive path is broken. Therefore, the primary particles are aggregated to form secondary particles rather than a single particle active material consisting of only primary particles, so that the expansion and contraction stress is relieved and deterioration is prevented.

  In addition, spherical or oval spherical particles are less oriented during molding of the electrode than plate-like equiaxed particles, so there is less expansion and contraction of the electrode during charge and discharge, and an electrode is produced. The mixing with the conductive material is also preferable because it can be easily mixed uniformly.

(5) Tap Density Tap density lithium-titanium composite oxide is preferably from 0.05 g · ^{cm -3} or more, 0.1 g · ^{cm -3} or more, and more preferably 0.2 g · ^{cm -3} or more, 0.4 g · cm ⁻³ or more is particularly preferable, 2.8 g · cm ⁻³ or less is preferable, 2.4 g · cm ⁻³ or less is further preferable, and 2 g · cm ⁻³ or less is particularly preferable. When the tap density is less than the above range, the packing density is difficult to increase when used as a negative electrode, and the contact area between particles decreases, so that the resistance between particles increases and the output resistance may increase. On the other hand, if the above range is exceeded, the voids between the particles in the electrode may become too small, and the output resistance may increase due to a decrease in the flow path of the non-aqueous electrolyte solution.

The tap density is measured by passing through a sieve having an opening of 300 μm, dropping the sample onto a 20 cm ³ tapping cell and filling the sample to the upper end surface of the cell, and then measuring a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Using a tap denser, tapping with a stroke length of 10 mm is performed 1000 times, and the density is calculated from the volume at that time and the weight of the sample. The tap density calculated by the measurement is defined as the tap density of the lithium titanium composite oxide of the present invention.

(6) Circularity When the circularity is measured as the spherical degree of the lithium titanium composite oxide, it is preferably within the following range. The circularity is defined as “circularity = (peripheral length of an equivalent circle having the same area as the particle projection shape) / (actual perimeter of the particle projection shape)”. It becomes.

  The circularity of the lithium-titanium composite oxide is preferably as close to 1, and is usually 0.10 or more, preferably 0.80 or more, more preferably 0.85 or more, and particularly preferably 0.90 or more. High current density charge / discharge characteristics improve as the circularity increases. Therefore, when the circularity is less than the above range, the filling property of the negative electrode active material is lowered, the resistance between particles is increased, and the high current density charge / discharge characteristics may be lowered for a short time.

  The circularity is measured using a flow type particle image analyzer (FPIA manufactured by Sysmex Corporation). About 0.2 g of a sample was dispersed in a 0.2% by mass aqueous solution (about 50 mL) of polyoxyethylene (20) sorbitan monolaurate as a surfactant, and irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute. The detection range is specified as 0.6 to 400 μm, and the particle size is measured in the range of 3 to 40 μm. The circularity determined by the measurement is defined as the circularity of the lithium titanium composite oxide of the present invention.

(7) Aspect ratio The aspect ratio of the lithium titanium composite oxide is usually 1 or more and usually 5 or less, preferably 4 or less, more preferably 3 or less, and particularly preferably 2 or less. If the aspect ratio exceeds the above range, streaking or a uniform coated surface cannot be obtained when forming an electrode plate, and high current density charge / discharge characteristics may be deteriorated for a short time. The lower limit of the above range is the theoretical lower limit value of the aspect ratio of the lithium titanium composite oxide.

  The aspect ratio is measured by magnifying and observing lithium titanium composite oxide particles with a scanning electron microscope. Arbitrary 50 particles fixed on the end face of a metal having a thickness of 50 μm or less are selected, and the stage on which the sample is fixed is rotated and tilted for each, and the maximum particle size is obtained when three-dimensionally observed. The diameter A and the shortest diameter B perpendicular to it are measured, and the average value of A / B is obtained. The aspect ratio (A / B) obtained by the measurement is defined as the aspect ratio of the lithium titanium composite oxide of the present invention.

(8) Method for producing negative electrode active material The method for producing lithium-titanium composite oxide is not particularly limited as long as it does not exceed the gist of the present invention. The method is used.

For example, a method of obtaining an active material by uniformly mixing a titanium source material such as titanium oxide and a source material of another element and a Li source such as LiOH, Li ₂ CO ₃ , or LiNO ₃ as necessary, and firing at a high temperature. Is mentioned.

In particular, various methods are conceivable for producing a spherical or elliptical active material. As an example, a titanium precursor material such as titanium oxide and, if necessary, a raw material material of another element are dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to create a spherical precursor. There is a method in which the active material is obtained by recovering and drying it as necessary, and then adding a Li source such as LiOH, Li ₂ CO ₃ , or LiNO ₃ and baking at a high temperature.

As another example, a titanium raw material such as titanium oxide and, if necessary, a raw material of another element are dissolved or pulverized and dispersed in a solvent such as water. A method of obtaining an active material by adding a Li source such as LiOH, Li ₂ CO ₃ , LiNO _{3 and the} like to an elliptical spherical precursor and baking at a high temperature can be mentioned.

As yet another method, a titanium raw material such as titanium oxide, a Li source such as LiOH, Li ₂ CO ₃ and LiNO ₃ and a raw material of another element as necessary are dissolved or pulverized in a solvent such as water. There is a method in which it is dispersed and dried by a spray dryer or the like to obtain a spherical or elliptical precursor, which is then fired at a high temperature to obtain an active material.

  Also, during these steps, elements other than Ti, such as Al, Mn, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, C, Si, Sn , Ag may be present in the metal oxide structure containing titanium and / or in contact with the oxide containing titanium. By containing these elements, the operating voltage and capacity of the battery can be controlled.

(9) Electrode preparation Any known method can be used to manufacture the electrode. For example, it is formed by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, etc. to a negative electrode active material to form a slurry, which is applied to a current collector, dried and then pressed. Can do.

  The thickness of the negative electrode active material layer per side in the stage immediately before the non-aqueous electrolyte injection process of the battery is usually 15 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and the upper limit is 150 μm or less, preferably 120 μm. Below, more preferably 100 μm or less. If it exceeds this range, the non-aqueous electrolyte solution hardly penetrates to the vicinity of the current collector interface, and thus the high current density charge / discharge characteristics may deteriorate. On the other hand, below this range, the volume ratio of the current collector to the negative electrode active material increases, and the battery capacity may decrease. Further, the negative electrode active material may be roll-formed to form a sheet electrode, or may be formed into a pellet electrode by compression molding.

(10) Current collector As the current collector for holding the negative electrode active material, a known material can be arbitrarily used. Examples of the current collector for the negative electrode include metal materials such as copper, nickel, aluminum, stainless steel, and nickel-plated steel. Among these, copper or aluminum is particularly preferable from the viewpoint of ease of processing and cost.

  The shape of the current collector includes, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, and a foam metal when the current collector is a metal material. Among them, a metal foil film containing copper (Cu) and / or aluminum (Al) is preferable, copper foil and aluminum foil are more preferable, rolled copper foil by a rolling method, and electrolytic copper by an electrolytic method are more preferable. There are foils, both of which can be used as current collectors.

  In addition, when the thickness of the copper foil is less than 25 μm, a copper alloy (phosphor bronze, titanium copper, Corson alloy, Cu—Cr—Zr alloy, etc.) having higher strength than pure copper can be used. Moreover, since the specific gravity of aluminum foil is light, when it is used as a current collector, the weight of the battery can be reduced and can be preferably used.

  A current collector made of a copper foil produced by a rolling method is suitable for use in a small cylindrical battery because the copper crystals are arranged in the rolling direction so that the negative electrode is hard to crack even if it is rounded sharply or rounded at an acute angle. be able to.

  For example, an electrolytic copper foil is prepared by immersing a metal drum in an electrolytic solution in which copper ions are dissolved, and flowing current while rotating the copper drum, thereby depositing copper on the surface of the drum and peeling it off. It is obtained. Copper may be deposited on the surface of the rolled copper foil by an electrolytic method. One side or both sides of the copper foil may be subjected to a roughening treatment or a surface treatment (for example, a chromate treatment having a thickness of about several nm to 1 μm, a base treatment such as Ti).

Further, the following physical properties are desired for the current collector substrate.
(10-1) Average surface roughness (Ra)
The average surface roughness (Ra) of the active material thin film forming surface of the current collector substrate defined by the method described in JIS B0601-1994 is not particularly limited, but is usually 0.01 μm or more, preferably 0.03 μm or more. Further, it is usually 1.5 μm or less, preferably 1.3 μm or less, and more preferably 1.0 μm or less.

  This is because when the average surface roughness (Ra) of the current collector substrate is within the above range, good charge / discharge cycle characteristics can be expected. In addition, the area of the interface with the active material thin film is increased, and the adhesion with the negative electrode active material thin film is improved. The upper limit value of the average surface roughness (Ra) is not particularly limited, but those having an average surface roughness (Ra) exceeding 1.5 μm are generally available as foils having a practical thickness as a battery. Since it is difficult, those of 1.5 μm or less are usually used.

(10-2) Tensile strength Tensile strength is obtained by dividing the maximum tensile force required until the test piece breaks by the cross-sectional area of the test piece. The tensile strength in the present invention is measured by the same apparatus and method as described in JISZ2241 (metal material tensile test method).

The tensile strength of the current collector substrate is not particularly limited, is generally 50 N · ^{mm -2} or more, preferably 100 N · ^{mm -2} or more, more preferably 150 N · ^{mm -2} or more. The tensile strength is preferably as high as possible, but usually 1000 N · mm ⁻² or less is desirable from the viewpoint of industrial availability. If the current collector substrate has a high tensile strength, cracking of the current collector substrate due to expansion / contraction of the active material thin film accompanying charging / discharging can be suppressed, and good cycle characteristics can be obtained.

(10-3) 0.2% proof stress 0.2% proof stress is the size of a load necessary to give a plastic (permanent) strain of 0.2%. It means that 0.2% deformation has occurred even when loaded. The 0.2% yield strength is measured by the same apparatus and method as the tensile strength.

0.2% proof stress of the current collector substrate is not particularly limited, normally 30 N · ^{mm -2} or more, preferably 100 N · ^{mm -2} or more, particularly preferably 150 N · ^{mm -2} or more. The 0.2% proof stress is preferably as high as possible, but usually 900 N · mm ⁻² or less is desirable from the viewpoint of industrial availability. If the current collector substrate has a high 0.2% proof stress, plastic deformation of the current collector substrate due to expansion / contraction of the active material thin film accompanying charging / discharging can be suppressed, and good cycle characteristics can be obtained. This is because it can.

(10-4) Thickness of current collector Although the thickness of the current collector is arbitrary, it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, 100 μm or less. Is preferably 50 μm or less. When the thickness of the current collector is thinner than 1 μm, the strength may be reduced, which may make application difficult. Moreover, when it becomes thicker than 100 micrometers, the shape of electrodes, such as winding, may be changed. The current collector may be mesh.

(11) Thickness ratio between current collector and active material layer The thickness ratio between the current collector and active material layer is not particularly limited, but “(the active material layer on one side immediately before non-aqueous electrolyte injection) The value of “thickness) / (current collector thickness)” is usually 150 or less, preferably 20 or less, more preferably 10 or less, and usually 0.1 or more, preferably 0.4 or more. One or more is more preferable. When the ratio of the thickness of the current collector to the negative electrode active material layer exceeds the above range, the current collector may generate heat due to Joule heat during high current density charge / discharge. On the other hand, below the above range, the volume ratio of the current collector to the negative electrode active material increases, and the battery capacity may decrease.

(12) Electrode density The electrode structure when the negative electrode active material is converted into an electrode is not particularly limited, but the density of the active material present on the current collector is preferably 1 g · cm ⁻³ or more, and 1.2 g・ Cm ⁻³ is more preferable, 1.3 g · cm ⁻³ or more is further preferable, 1.5 g · cm ⁻³ or more is particularly preferable, 3 g · cm ⁻³ or less is preferable, and 2.5 g · cm ^−3. The following is more preferable, 2.2 g · cm ⁻³ or less is further preferable, and 2 g · cm ⁻³ or less is particularly preferable. When the density of the active material present on the current collector exceeds the above range, the binding between the current collector and the negative electrode active material becomes weak, and the electrode and the active material may be separated. On the other hand, below the above range, the conductivity between the negative electrode active materials may decrease, and the battery resistance may increase.

(13) Binder The binder for binding the negative electrode active material is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte and the solvent used during electrode production.

  Specific examples include resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, Rubber polymers such as NBR (acrylonitrile / butadiene rubber) and ethylene / propylene rubber; styrene / butadiene / styrene block copolymer and hydrogenated products thereof; EPDM (ethylene / propylene / diene terpolymer), styrene / Thermoplastic elastomeric polymers such as ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers and hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate , Soft resinous polymers such as ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, etc. And a polymer composition having ion conductivity of alkali metal ions (particularly lithium ions). These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  The solvent for forming the slurry is not particularly limited as long as it is a solvent that can dissolve or disperse the negative electrode active material, binder, thickener and conductive material used as necessary. Alternatively, either an aqueous solvent or an organic solvent may be used.

  Examples of the aqueous solvent include water, alcohol and the like, and examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N , N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, dimethyl ether, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like. In particular, when an aqueous solvent is used, a dispersant or the like is added in addition to the above-described thickener, and a slurry is formed using a latex such as SBR. In addition, these may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 20% by mass or less, 15% by mass. % Or less is preferable, 10 mass% or less is more preferable, and 8 mass% or less is particularly preferable. When the ratio of the binder with respect to a negative electrode active material exceeds the said range, the binder ratio in which the amount of binders does not contribute to battery capacity may increase, and battery capacity may fall. On the other hand, if it is below the above range, the strength of the negative electrode is lowered, which may be undesirable in the battery production process.

  In particular, when a rubbery polymer represented by SBR is contained as a main component, the ratio of the binder to the active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, and 6 mass% or more is still more preferable, and it is 5 mass% or less normally, 3 mass% or less is preferable, and 2 mass% or less is still more preferable. Further, when the main component contains a fluorine polymer represented by polyvinylidene fluoride, the ratio to the active material is 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, Usually, it is 15 mass% or less, 10 mass% or less is preferable, and 8 mass% or less is still more preferable.

  A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  Further, when a thickener is used, the ratio of the thickener to the negative electrode active material is 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, Usually, it is 5 mass% or less, 3 mass% or less is preferable, and 2 mass% or less is still more preferable. When the ratio of the thickener to the negative electrode active material is less than the above range, applicability may be significantly reduced. Moreover, when it exceeds the said range, the ratio of the active material which occupies for a negative electrode active material layer will fall, the problem that the capacity | capacitance of a battery falls, and the resistance between negative electrode active materials may increase.

<2-4 positive electrode>
The positive electrode used for the non-aqueous electrolyte battery of the present invention will be described below.

<2-4-1. Cathode active material>
The positive electrode active material used for the positive electrode will be described below.

(1) Composition The positive electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. For example, a material containing lithium and at least one transition metal is preferable. Specific examples include lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds.

V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferable as the transition metal of the lithium transition metal composite oxide. Specific examples include lithium-cobalt composite oxides such as LiCoO ₂ and LiNiO ₂ . Lithium / nickel composite oxides, LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO _{4 and} other lithium / manganese composite oxides, Al, Ti , V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, and those substituted with other metals such as Si.

As specific examples of the substituted ones, for example, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O _{4 and the} like.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples include, for example, LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ). ₃ , iron phosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other metals.

(2) Surface coating A material having a composition different from that of the main constituent of the positive electrode active material (hereinafter referred to as “surface adhering substance” as appropriate) may be used on the surface of the positive electrode active material. . Examples of surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, Examples thereof include sulfates such as calcium sulfate and aluminum sulfate, and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.

  These surface adhering substances are, for example, a method in which they are dissolved or suspended in a solvent and impregnated and added to the positive electrode active material and then dried, or a surface adhering substance precursor is dissolved or suspended in a solvent and impregnated and added to the positive electrode active material. Then, it can be made to adhere to the surface of the positive electrode active material by a method of reacting by heating or the like, a method of adding to the positive electrode active material precursor and firing simultaneously.

  The mass of the surface adhering material adhering to the surface of the positive electrode active material is usually 0.1 ppm or more, preferably 1 ppm or more, more preferably 10 ppm or more, and usually 20% with respect to the mass of the positive electrode active material. Or less, preferably 10% or less, more preferably 5% or less.

  The surface adhering substance can suppress the oxidation reaction of the non-aqueous electrolyte on the surface of the positive electrode active material, and can improve the battery life. However, when the adhesion amount is less than the above range, the effect is not sufficiently exhibited. When the adhesion amount is more than the above range, the resistance may increase in order to inhibit the entry / exit of lithium ions, so the above range is preferable.

(3) Shape As the shape of the positive electrode active material particles, a lump shape, a polyhedron shape, a sphere shape, an oval sphere shape, a plate shape, a needle shape, a column shape, etc., which are conventionally used, are used. It is preferable to form secondary particles, and the shape of the secondary particles is spherical or elliptical.

  In general, an electrochemical element expands and contracts as the active material in the electrode expands and contracts as it is charged and discharged. Therefore, the active material is easily damaged due to the stress or the conductive path is broken. Therefore, the primary particles are aggregated to form secondary particles rather than a single particle active material having only primary particles, so that the stress of expansion and contraction is relieved and deterioration is prevented.

  In addition, spherical or oval spherical particles are less oriented at the time of forming the electrode than the plate-like equiaxially oriented particles, so there is less expansion and contraction of the electrode during charge and discharge, and when creating the electrode Also in the mixing with the conductive material, it is preferable because it is easily mixed uniformly.

(4) Tap density The tap density of the positive electrode active material is usually 1.3 g · cm ⁻³ or more, preferably 1.5 g · cm ⁻³ or more, more preferably 1.6 g · cm ⁻³ or more. 7 g · cm ⁻³ or more is particularly preferable, usually 2.5 g · cm ⁻³ or less, and preferably 2.4 g · cm ⁻³ or less.

  By using a metal composite oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. Therefore, when the tap density of the positive electrode active material is lower than the above range, the amount of the dispersion medium necessary for forming the positive electrode active material layer increases, and the necessary amount of the conductive material and the binder increases. The filling rate of the positive electrode active material is limited, and the battery capacity may be limited. In general, the tap density is preferably as large as possible, but there is no particular upper limit. However, if the tap density is below the above range, diffusion of lithium ions in the positive electrode active material layer as a medium becomes rate-determining and load characteristics are likely to deteriorate. There is a case.

The tap density is measured by passing a sieve having an opening of 300 μm, dropping the sample onto a 20 cm ³ tapping cell to fill the cell volume, and then using a powder density measuring instrument (for example, a tap denser manufactured by Seishin Enterprise Co., Ltd.). The tapping with a stroke length of 10 mm is performed 1000 times, and the density is calculated from the volume at that time and the weight of the sample. The tap density calculated by the measurement is defined as the tap density of the positive electrode active material of the present invention.

(5) Median diameter d50
The median diameter d50 (secondary particle diameter when primary particles are aggregated to form secondary particles) of the positive electrode active material particles should also be measured using a laser diffraction / scattering particle size distribution analyzer. Can do.

  The median diameter d50 is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more, particularly preferably 3 μm or more, and usually 20 μm or less, preferably 18 μm or less, more preferably 16 μm or less. 15 μm or less is particularly preferable. If the median diameter d50 is below the above range, a high bulk density product may not be obtained. If the median diameter d50 is above the above range, it takes time to diffuse lithium in the particles. That is, when an active material, a conductive material, a binder, or the like is slurried with a solvent and applied as a thin film, streaks may occur.

  In addition, the filling property at the time of positive electrode preparation can be further improved by mixing two or more types of positive electrode active materials having different median diameters d50 at an arbitrary ratio.

  The median diameter d50 is measured by using a 0.1% by mass sodium hexametaphosphate aqueous solution as a dispersion medium, and using LA-920 manufactured by HORIBA, Ltd. as a particle size distribution meter, the refractive index is adjusted to 1.24 after ultrasonic dispersion for 5 minutes. Set and measure.

(6) Average primary particle diameter When primary particles aggregate to form secondary particles, the average primary particle diameter of the positive electrode active material is usually 0.01 μm or more, preferably 0.05 μm or more, and The thickness is more preferably 08 μm or more, particularly preferably 0.1 μm or more, and usually 3 μm or less, preferably 2 μm or less, more preferably 1 μm or less, and particularly preferably 0.6 μm or less. If the above range is exceeded, it may be difficult to form spherical secondary particles, which may adversely affect the powder filling property, or the specific surface area will be greatly reduced, which may increase the possibility that the battery performance such as output characteristics will deteriorate. is there. Further, if the value is below the above range, the performance of the secondary battery may be deteriorated, for example, the reversibility of charge / discharge is inferior because the crystal is not developed.

  The average primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for any 50 primary particles and obtained by taking the average value. It is done.

(7) BET specific surface area As for the BET specific surface area of the positive electrode active material, the value of the specific surface area measured using the BET method is usually 0.2 m ² · g ⁻¹ or more, and 0.3 m ² · g ⁻¹ or more. 0.4 m ² · g ⁻¹ or more is more preferable, usually 4.0 m ² · g ⁻¹ or less, preferably 2.5 m ² · g ⁻¹ or less, and 1.5 m ² · g ^{−. 1} or less is more preferable. When the value of the BET specific surface area is below the above range, the battery performance tends to be lowered. Moreover, when it exceeds the said range, a tap density becomes difficult to raise and the applicability | paintability at the time of positive electrode active material formation may fall.

  The BET specific surface area is measured using a surface area meter (a fully automatic surface area measuring device manufactured by Okura Riken). The sample was preliminarily dried at 150 ° C. for 30 minutes under a nitrogen flow, and then a nitrogen helium mixed gas that was accurately adjusted so that the relative pressure of nitrogen with respect to atmospheric pressure was 0.3 was used. It is measured by the nitrogen adsorption BET one-point method by the flow method. The specific surface area determined by the measurement is defined as the BET specific surface area of the anode active material of the present invention.

(8) Method for Producing Positive Electrode Active Material The method for producing the positive electrode active material is not particularly limited as long as it does not exceed the gist of the present invention, but there are several methods, which are common as methods for producing inorganic compounds. The method is used.

In particular, various methods are conceivable for producing a spherical or elliptical active material. For example, transition metal source materials such as transition metal nitrates and sulfates, and other element source materials as required. Is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to produce and recover a spherical precursor, which is dried as necessary, and then LiOH, Li ₂ CO ₃ , LiNO There is a method in which an active material is obtained by adding a Li source such as ₃ and baking at a high temperature.

In addition, as an example of another method, transition metal raw materials such as transition metal nitrates, sulfates, hydroxides, oxides and the like, and if necessary, raw materials of other elements are dissolved or pulverized and dispersed in a solvent such as water. Then, it is dry-molded with a spray dryer or the like to obtain a spherical or oval spherical precursor, and a Li source such as LiOH, Li ₂ CO ₃ , LiNO ₃ is added to the precursor and calcined at a high temperature to obtain an active material Is mentioned.

Examples of other methods include transition metal source materials such as transition metal nitrates, sulfates, hydroxides, oxides, Li sources such as LiOH, Li ₂ CO ₃ , LiNO ₃ , and other elements as necessary. The raw material is dissolved or pulverized and dispersed in a solvent such as water, and is then dried by a spray dryer or the like to form a spherical or elliptical precursor, which is fired at a high temperature to obtain an active material. Can be mentioned.

<2-4-2. Electrode structure and fabrication method>
Below, the structure of the positive electrode used for this invention and its preparation method are demonstrated.

(1) Method for Producing Positive Electrode The positive electrode is produced by forming a positive electrode active material layer containing positive electrode active material particles and a binder on a current collector. The production of the positive electrode using the positive electrode active material can be produced by any known method. That is, a positive electrode active material and a binder, and if necessary, a conductive material and a thickener mixed in a dry form are pressure-bonded to a positive electrode current collector, or these materials are liquid media A positive electrode can be obtained by forming a positive electrode active material layer on the current collector by applying it to a positive electrode current collector and drying it as a slurry by dissolving or dispersing in a slurry.

  The content of the positive electrode active material in the positive electrode active material layer is usually 10% by mass or more, preferably 30% by mass or more, particularly preferably 50% by mass or more, and usually 99.9% by mass or less, preferably 99% by mass. It is as follows. This is because if the content of the positive electrode active material in the positive electrode active material layer is less than the above range, the electric capacity may be insufficient. Moreover, it is because the intensity | strength of a positive electrode may be insufficient when it exceeds the said range. In addition, the positive electrode active material powder in this invention may be used individually by 1 type, and may use together 2 or more types of a different composition or different powder physical properties by arbitrary combinations and ratios.

(2) Conductive material As the conductive material, a known conductive material can be arbitrarily used. Specific examples include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite (graphite); carbon black such as acetylene black; and carbonaceous materials such as amorphous carbon such as needle coke. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  The conductive material is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and usually 50% by mass or less, preferably 30% by mass or less in the positive electrode active material layer. More preferably, it is used so as to contain 15% by mass or less. If the content is lower than the above range, the conductivity may be insufficient. Moreover, when it exceeds the said range, battery capacity may fall.

(3) Binder The binder used in the production of the positive electrode active material layer is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte solution and the solvent used during electrode production.

  In the case of the coating method, any material can be used as long as it is dissolved or dispersed in the liquid medium used during electrode production. Specific examples include polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, nitro Resin polymers such as cellulose; rubbery polymers such as SBR (styrene butadiene rubber), NBR (acrylonitrile butadiene rubber), fluorine rubber, isoprene rubber, butadiene rubber, ethylene propylene rubber; styrene butadiene styrene block Copolymer or its hydrogenated product, EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / butadiene / ethylene copolymer, styrene / isoprene / styrene block copolymer or its hydrogenated product, etc. Thermoplastic Stoma-like polymers; soft resin-like polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride (PVdF), Examples include fluorine-based polymers such as polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene / ethylene copolymers; polymer compositions having ion conductivity of alkali metal ions (particularly lithium ions). In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, and usually 80% by mass or less, and 60% by mass. % Or less is preferable, 40% by mass or less is more preferable, and 10% by mass or less is particularly preferable. When the ratio of the binder is below the above range, the positive electrode active material cannot be sufficiently retained, the positive electrode has insufficient mechanical strength, and battery performance such as cycle characteristics may be deteriorated. Moreover, when it exceeds the said range, it may lead to a battery capacity or electroconductivity fall.

(4) Liquid medium The liquid medium for forming the slurry may be a solvent capable of dissolving or dispersing the positive electrode active material, the conductive material, the binder, and the thickener used as necessary. For example, the type is not particularly limited, and either an aqueous solvent or an organic solvent may be used.

  Examples of the aqueous medium include water, a mixed medium of alcohol and water, and the like. Examples of organic media include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone. Esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N, N-dimethylaminopropylamine; ethers such as diethyl ether and tetrahydrofuran (THF); N-methylpyrrolidone (NMP) and dimethylformamide And amides such as dimethylacetamide; aprotic polar solvents such as hexamethylphosphalamide and dimethyl sulfoxide. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

(5) Thickener When using an aqueous medium as a liquid medium for forming a slurry, it is preferable to make a slurry using a thickener and a latex such as styrene butadiene rubber (SBR). A thickener is usually used to adjust the viscosity of the slurry.

  The thickener is not limited as long as the effect of the present invention is not significantly limited. Specifically, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and salts thereof Etc. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  Further, when using a thickener, the ratio of the thickener to the active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, Usually, it is 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. If it falls below the above range, applicability may be remarkably reduced, and if it exceeds the above range, the ratio of the active material in the positive electrode active material layer is lowered, the battery capacity is reduced, and the resistance between the positive electrode active materials. May increase.

(6) Consolidation The positive electrode active material layer obtained by coating and drying is preferably consolidated by a hand press, a roller press or the like in order to increase the packing density of the positive electrode active material. The density of the positive electrode active material layer is preferably 1 g · cm ⁻³ or more, more preferably 1.5 g · cm ⁻³ or more, particularly preferably 2 g · cm ⁻³ or more, and preferably 4 g · cm ⁻³ or less. 3.5 g · cm ⁻³ or less is more preferable, and 3 g · cm ⁻³ or less is particularly preferable.

  If the density of the positive electrode active material layer exceeds the above range, the permeability of the non-aqueous electrolyte solution to the vicinity of the current collector / active material interface may decrease, and the charge / discharge characteristics at a high current density may decrease. Moreover, when less than the said range, the electroconductivity between active materials may fall and battery resistance may increase.

(7) Current collector The material of the positive electrode current collector is not particularly limited, and any known material can be used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbonaceous materials such as carbon cloth and carbon paper. Of these, metal materials, particularly aluminum, are preferred.

  Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, foam metal, etc. A carbon thin film, a carbon cylinder, etc. are mentioned. Of these, metal thin films are preferred. In addition, you may form a thin film suitably in mesh shape.

  The thickness of the current collector is arbitrary, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, more preferably 50 μm or less. If the thin film is thinner than the above range, the strength required for the current collector may be insufficient. Moreover, when a thin film is thicker than the said range, a handleability may be impaired.

<2-5. Separator>
Usually, a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit. In this case, the nonaqueous electrolytic solution of the present invention is usually used by impregnating the separator.

  There is no restriction | limiting in particular about the material and shape of a separator, A well-known thing can be arbitrarily employ | adopted unless the effect of this invention is impaired remarkably. Among them, a resin, glass fiber, inorganic material, etc. formed of a material that is stable with respect to the non-aqueous electrolyte solution of the present invention is used, and a porous sheet or a nonwoven fabric-like material having excellent liquid retention properties is used. Is preferred.

  As materials for the resin and the glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, polyethersulfone, glass filters and the like can be used. Of these, glass filters and polyolefins are preferred, and polyolefins are more preferred. These materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. If the separator is too thin than the above range, the insulating properties and mechanical strength may decrease. On the other hand, if it is thicker than the above range, not only battery performance such as rate characteristics may be lowered, but also the energy density of the entire non-aqueous electrolyte battery may be lowered.

  Furthermore, when a porous material such as a porous sheet or nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Moreover, it is 90% or less normally, 85% or less is preferable and 80% or less is still more preferable. If the porosity is too smaller than the above range, the membrane resistance tends to increase and the rate characteristics tend to deteriorate. Moreover, when larger than the said range, it exists in the tendency for the mechanical strength of a separator to fall and for insulation to fall.

  Moreover, although the average pore diameter of a separator is also arbitrary, it is 1.0 micrometer or less normally, 0.5 micrometer or less is preferable, and it is 0.05 micrometer or more normally. If the average pore diameter exceeds the above range, a short circuit tends to occur. On the other hand, below the above range, the film resistance may increase and the rate characteristics may deteriorate.

  On the other hand, as the inorganic material, for example, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used. Things are used.

  As the form, a thin film shape such as a non-woven fabric, a woven fabric, or a microporous film is used. In the thin film shape, those having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, a porous layer may be formed by using alumina particles having a 90% particle size of less than 1 μm on both surfaces of the positive electrode and using a fluororesin as a binder.

<2-6. Battery design>
[Electrode group]
The electrode group has a laminated structure in which the positive electrode plate and the negative electrode plate are interposed via the separator, and a structure in which the positive electrode plate and the negative electrode plate are wound in a spiral shape via the separator. Either may be used. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupation ratio) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less. . When the electrode group occupancy is below the above range, the battery capacity decreases. Also, if the above range is exceeded, the void space is small, the battery expands, and the member expands or the vapor pressure of the electrolyte liquid component increases and the internal pressure rises. In some cases, a gas release valve that lowers various characteristics such as storage at high temperature and the like, or releases the internal pressure to the outside is activated.

[Current collection structure]
The current collecting structure is not particularly limited, but in order to more effectively realize the high current density charge / discharge characteristics by the non-aqueous electrolyte of the present invention, the resistance of the wiring portion and the joint portion is reduced. A structure is preferred. Thus, when internal resistance is reduced, the effect of using the non-aqueous electrolyte solution of this invention is exhibited especially favorable.

  In the case where the electrode group has the laminated structure described above, a structure formed by bundling the metal core portions of the electrode layers and welding them to the terminals is preferably used. When the area of one electrode increases, the internal resistance increases. Therefore, it is also preferable to provide a plurality of terminals in the electrode to reduce the resistance. When the electrode group has the winding structure described above, the internal resistance can be lowered by providing a plurality of lead structures for the positive electrode and the negative electrode, respectively, and bundling the terminals.

  By optimizing the above structure, the internal resistance can be made as small as possible. In a battery used at a high current, the impedance measured by the 10 kHz AC method (hereinafter abbreviated as “DC resistance component”) is preferably 10 milliohms (mΩ) or less, and the DC resistance component is 5 mΩ or less. Is more preferable. When the DC resistance component is 0.1 mΩ or less, the output characteristics are improved, but the ratio of the current collecting structure used increases and the battery capacity may decrease.

[Exterior case]
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the non-aqueous electrolyte used. Specifically, a nickel-plated steel plate, stainless steel, aluminum, an aluminum alloy, a metal such as a magnesium alloy, or a laminated film (laminate film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, an aluminum or aluminum alloy metal or a laminate film is preferably used.

  In the exterior case using the above metals, a laser-sealed, resistance-welded, ultrasonic welding is used to weld the metals together to form a sealed sealed structure, or a caulking structure using the above-mentioned metals via a resin gasket To do. Examples of the outer case using the laminate film include those having a sealed and sealed structure by heat-sealing resin layers. In order to improve the sealing performance, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when a resin layer is heat-sealed through a current collecting terminal to form a sealed structure, a metal and a resin are joined, so that a resin having a polar group or a modified group having a polar group introduced as an intervening resin is used. Resins are preferably used.

[Protective element]
As a protective element, PTC (Positive Temperature Coefficient), thermal fuse, thermistor, whose resistance increases when abnormal heat or excessive current flows, cut off current flowing in the circuit due to sudden rise in battery internal pressure or internal temperature at abnormal heat generation And the like (current cutoff valve). It is preferable to select a protective element that does not operate under normal use at a high current, and it is more preferable that the protective element has a design that does not cause abnormal heat generation or thermal runaway even without the protective element.

[Exterior body]
The non-aqueous electrolyte battery of the present invention is usually configured by housing the non-aqueous electrolyte, the negative electrode, the positive electrode, the separator, and the like in an exterior body. There is no restriction | limiting in this exterior body, As long as the effect of this invention is not impaired remarkably, a well-known thing can be employ | adopted arbitrarily. Specifically, the material of the exterior body is arbitrary, but usually, for example, nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, or the like is used.

  The shape of the exterior body is also arbitrary, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

[Action]
In the present invention, “monofluorophosphates and difluorophosphates” having an effect of reducing interfacial resistance, an effect of improving charge / discharge cycles, and the like are contained in a nonaqueous electrolytic solution using a room temperature molten salt. Although the operation and principle of the present invention exhibiting the effects described above are not clear, the present invention is not limited by the following operation and principle, but is considered as follows. That is, monofluorophosphates and difluorophosphates preferentially act on the electrode among the compounds constituting the nonaqueous electrolytic solution, and are concentrated or adsorbed on the electrode interface. This prevents the elution of the positive electrode active material into the non-aqueous electrolyte, suppresses the loss of the electron conduction path resulting from the volume change of the electrode active material due to charge / discharge, or lithium monofluorophosphate or difluorophosphorus. In the case of lithium acid, the function of increasing the lithium concentration on the electrode surface is obtained, and it is presumed that these have the effect of reducing the interface resistance and improving the charge / discharge cycle. In addition, monofluorophosphates and difluorophosphates are inorganic substances, and there is no generation of combustible gas resulting from their decomposition.

  Furthermore, lithium monofluorophosphate and lithium difluorophosphate have very high solubility in general-purpose non-aqueous electrolytes composed mainly of cyclic carbonates such as ethylene carbonate and chain carbonates such as dimethyl carbonate. Although it is low, it can be dissolved in a large amount in the ambient temperature molten salt as compared with the organic solvent electrolyte. In addition, the monofluorophosphate anion and difluorophosphate anion can be used as a counter anion of a room temperature molten salt. Thus, by combining monofluorophosphate or difluorophosphate and room temperature molten salt, the effects of reducing interface resistance and improving charge / discharge cycle characteristics can be brought out more prominently and synergistically. it can.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Each evaluation method of the battery obtained by the following Example and the comparative example is shown below.
[Discharge capacity evaluation]
The nonaqueous electrolyte battery was charged to 4.2 V at a constant current corresponding to 0.1 C at 60 ° C., and then discharged to 3 V at a constant current of 0.1 C. This was performed 20 cycles, and the discharge capacity (%) after 20 cycles when the initial discharge capacity was set to 100 was determined, and was defined as “post-cycle discharge capacity (%)”. Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and 0.1C represents a current value of 1/10 thereof.

Example 1

[Production of non-aqueous electrolyte]
Under a dry argon atmosphere, fully dried lithium bis (trifluoromethanesulfonyl) imide (hereinafter referred to as “BMPTFSI”) in N-butyl-N-methylpyrrolidinium bis (trifluoromethanesulfonyl) imide (hereinafter abbreviated as “BMPTFSI”). (Abbreviated as “LiTFSI”) was dissolved at a rate of 0.4 mol / L. Furthermore, 2 parts by weight of sufficiently dried lithium difluorophosphate (hereinafter sometimes referred to as “LiPO ₂ F ₂ ”) is dissolved in 98 parts by weight of a mixture of BMPTFSI and LiTFSI, and non-aqueous electrolysis is performed. Liquid.

[Manufacture of non-aqueous electrolyte batteries]
90% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 5% by mass of acetylene black as a conductive material, and 5% by mass of polyvinylidene fluoride (PVdF) as a binder, an N-methylpyrrolidone solvent Mixed in to a slurry. The obtained slurry was applied to one side of an aluminum foil having a thickness of 15 μm, dried, and rolled to a thickness of 80 μm with a press machine, and the electrode was punched into a disk shape having a diameter of 12.5 mm as the size of the active material layer. A non-aqueous electrolyte battery, which is a coin-type lithium secondary battery constructed using a lithium foil as a counter electrode through a separator impregnated with a non-aqueous electrolyte, was prepared and evaluated. Table 1 shows the components of the nonaqueous electrolytic solution, and Table 2 shows the evaluation results.

Example 2
In the nonaqueous electrolytic solution of Example 1, N-butyl-N, N, N-trimethylammonium bis (trifluoromethanesulfonyl) imide (hereinafter abbreviated as “BTMATFSI”) was used instead of BMPTFSI. In the same manner as in Example 1, a coin-type lithium secondary battery was produced and evaluated. Table 1 shows the components of the nonaqueous electrolytic solution, and Table 2 shows the evaluation results.

Example 3
In the nonaqueous electrolytic solution of Example 1, N, N-dimethyl-N-methyl-N-methoxyethylammonium bis (trifluoromethanesulfonyl) imide (hereinafter abbreviated as “DEMETFSI”) was used instead of BMPTFSI. A coin-type lithium secondary battery was produced and evaluated in the same manner as Example 1 except for the above. Table 1 shows the components of the nonaqueous electrolytic solution, and Table 2 shows the evaluation results.

Comparative Example 1
A coin-type lithium secondary battery was produced in the same manner as in Example 1 except that a non-aqueous electrolyte prepared by dissolving LiTFSI sufficiently dried at a ratio of 0.4 mol / L was used in BMPTFSI. And evaluated. Table 1 shows the components of the nonaqueous electrolytic solution, and Table 2 shows the evaluation results.

Comparative Example 2
A coin-type lithium secondary battery was produced in the same manner as in Example 1 except that a non-aqueous electrolyte prepared by dissolving LiTFSI sufficiently dried at a ratio of 0.4 mol / L in BTMATFSI was used. And evaluated. Table 1 shows the components of the nonaqueous electrolytic solution, and Table 2 shows the evaluation results.

Comparative Example 3
A coin-type lithium secondary battery was produced in the same manner as in Example 1 except that a non-aqueous electrolyte prepared by dissolving LiTFSI sufficiently dried at a ratio of 0.4 mol / L was used in DEMETFSI. And evaluated. Table 1 shows the components of the nonaqueous electrolytic solution, and Table 2 shows the evaluation results.

  As is clear from the results in Table 2, the batteries (Examples 1 to 3) using the non-aqueous electrolyte solution according to the present invention had high charge / discharge characteristics. On the other hand, in the battery (Comparative Examples 1-3) using what is not the non-aqueous electrolyte which concerns on this invention, the charge / discharge characteristic was inferior.

  Since the nonaqueous electrolyte battery using the nonaqueous electrolyte of the present invention maintains a high capacity and is excellent in safety and the like, it can be used for various known applications. Specific examples include, for example, notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs. , Walkie Talkie, Electronic Notebook, Calculator, Memory Card, Portable Tape Recorder, Radio, Backup Power Supply, Motor, Car, Motorcycle, Motorbike, Bicycle, Lighting Equipment, Toy, Game Equipment, Clock, Electric Tool, Strobe, Camera, etc. Can be mentioned.

Claims (5)

  A non-aqueous electrolyte comprising a lithium salt and a room temperature molten salt, wherein the non-aqueous electrolyte contains a monofluorophosphate and / or a difluorophosphate in the non-aqueous electrolyte. . The room temperature molten salt is a tertiary sulfonium salt having a structure represented by the general formula (1), a quaternary ammonium salt having a structure represented by the general formula (2), or a structure represented by the general formula (3). The nonaqueous electrolytic solution according to claim 1, which is a quaternary phosphonium salt.

[In General Formula (1), R ₁ , R ₂ and R ₃ each independently represents an organic group having 1 to 12 carbon atoms. However, two organic groups of R ₁ , R ₂ and R ₃ may be bonded to each other to form a ring structure. ]

[In General Formula (2), R ₄ , R ₅ , R ₆ and R ₇ each independently represents an organic group having 1 to 12 carbon atoms. However, two to four organic groups out of R ₄ , R ₅ , R ₆ and R ₇ may be bonded to each other to form a ring structure. R ₄ , R ₅ , R ₆ and R ₇ Of these, two organic groups are actually one organic group, and the organic group and the “N ⁺ ” atom may be linked by a double bond. ]

[In General Formula (3), R ₈ , R ₉ , R ₁₀ and R ₁₁ each independently represents an organic group having 1 to 12 carbon atoms. However, two to four organic groups out of R ₈ , R ₉ , R ₁₀ and R ₁₁ may be bonded to each other to form a ring structure. R ₈ , R ₉ , R ₁₀ and R ₁₁ Of these, two organic groups are actually one organic group, and the one organic group and the “P ⁺ ” atom may be linked by a double bond. ]   The monofluorophosphate and / or difluorophosphate is contained in a total amount of 0.001% by mass or more and 100% by mass or less based on the total amount of the non-aqueous electrolyte solution. 2. A non-aqueous electrolyte solution according to 2.   The room temperature molten salt is contained in an amount of 0.01% by mass or more and 100% by mass or less with respect to a non-aqueous electrolyte component other than lithium salt, monofluorophosphate, and difluorophosphate. 4. The non-aqueous electrolyte solution according to any one of 3.   A non-aqueous electrolyte battery comprising at least a negative electrode and a positive electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution is any one of claims 1 to 4. A non-aqueous electrolyte battery, characterized in that it is a non-aqueous electrolyte solution according to item 2.