JP6860782B2 - Additives for non-aqueous electrolytes, non-aqueous electrolytes using these additives, and non-aqueous electrolyte secondary batteries - Google Patents

Description

The present invention relates to an additive for a non-aqueous electrolyte solution, a non-aqueous electrolyte solution using the additive, and a non-aqueous electrolyte solution secondary battery.

As a means for improving the durability of non-aqueous electrolyte batteries, optimization of various battery components such as active materials for positive electrodes and negative electrodes has been studied. Non-aqueous electrolytes are no exception, and it has been proposed that an electrolysis film made of various durability improvers suppresses deterioration due to decomposition of the electrolyte on the surfaces of active positive and negative electrodes.

For example, Patent Document 1 contains non-aqueous oxalate salts such as lithium difluoro (bis (oxalate)) phosphate, lithium tetrafluoro (oxalate) phosphate, lithium difluoro (oxalate) borate, and lithium bis (oxalate) borate. A method of suppressing an increase in the internal resistance of a battery and deterioration of cycle characteristics by adding it to an electrolytic solution has been proposed.

Further, in Patent Document 2, in a lithium ion secondary battery, at least one unsaturated bond is formed at a ratio of 0.01 to 10% by mass of the non-aqueous electrolyte solution in order to form a immobilization layer on the electrode. An electrolytic solution for a secondary battery is disclosed, which comprises adding a soluble compound that can be reduced at an anode at a potential 1 V higher than that of lithium to form a mobilized layer. As the soluble compound containing an unsaturated bond, for example, it is disclosed that a carbonate compound having an unsaturated bond represented by vinylene carbonate (hereinafter sometimes referred to as "VC") is added.

Further, in Patent Document 3, in a lithium ion secondary battery, VC and Li are used with respect to 100 parts by mass of a non-aqueous electrolytic solution for the purpose of improving the capacity retention rate after repeating a charge / discharge cycle at a high temperature. [M (C ₂ O ₄ ) _x R _y ] (In the formula, M is one selected from the group consisting of P, Al, Si and C, R is the group consisting of a halogen group, an alkyl group and an alkyl halide group. Add one group selected from the above, x is a positive integer, y is 0 or a positive integer), and a total amount of 0.6 parts by mass or more and 3.9 parts by mass or less of an oxalate salt is added. An electrolytic solution for a secondary battery, characterized by the above, is disclosed.

Further, in Patent Document 4, at least non-aqueous electrolyte solution is provided for the purpose of suppressing a decrease in repeated charge / discharge characteristics (cycle characteristics) of a battery and providing a non-aqueous electrolyte solution for a secondary battery having excellent low temperature discharge characteristics. A non-aqueous electrolyte solution for a secondary battery containing a solvent, a lithium salt and a vinylene carbonate, wherein the content of the vinylene carbonate is in the range of 0.001% by mass to 3% by mass of the total mass of the electrolytic solution, and further. , A non-aqueous electrolyte solution for a secondary battery, characterized in that it contains 10 ppm or more of difluorophosphate with respect to the total mass of the electrolytic solution, is disclosed.

Durability-enhancing additives containing unsaturated bonds as described above are generally added as monomers. For example, when VC is added, in Patent Document 5, a polymerization inhibitor is also added so that the VC does not react in a portion other than where it should function and the battery does not swell. Further, in Patent Document 6, when a polymer gel layer containing an electrolytic solution containing VC is formed, it is gelled by cationic polymerization to prevent free radical species from being present in the system, and VC in the electrolytic solution. Is suppressed from decreasing due to the self-polymerization reaction. As described above, the durability-enhancing additive containing an unsaturated bond has been conventionally added as a monomer.

Japanese Unexamined Patent Publication No. 2005-032714 Japanese Unexamined Patent Publication No. 8-0455545 International Publication No. 2010/067549 JP-A-2007-141830 Japanese Unexamined Patent Publication No. 2008-034233 Japanese Unexamined Patent Publication No. 2008-282735

A non-aqueous electrolyte solution containing an oxalate salt and / or difluorophosphate and a carbonate compound containing an unsaturated bond, which has been conventionally added as a monomer, can be used in a non-aqueous electrolyte solution secondary battery. Although it exhibits excellent cycle characteristics, it tends to have low rate characteristics, and improvement is desired.
Therefore, according to the present invention, by adding an oxalate salt and / or difluorophosphate to a non-aqueous electrolyte solution, the cycle characteristics and rate characteristics can be exhibited in a well-balanced manner when used in a non-aqueous electrolyte solution secondary battery. An object of the present invention is to provide an additive for a non-aqueous electrolyte solution that can be produced.
Another object of the present invention is to provide a non-aqueous electrolyte solution having the additive for the non-aqueous electrolyte solution.
Another object of the present invention is to provide a non-aqueous electrolyte secondary battery provided with the non-aqueous electrolyte.

［式中、括弧の内部はそれぞれが繰り返し単位であることを意味する。Ｒは、水素原子、ハロゲン又は低級アルキル基を表す。Ｒは、全て同一であってもよく、異なっていてもよく、互いに連結して環状構造を有していてもよい。］ The present invention
It is a compound having a repeating unit represented by the following general formula [1].
The polystyrene-equivalent number average molecular weight is 170-5000.
It is an additive for a non-aqueous electrolyte solution to be contained in a non-aqueous electrolyte solution containing an oxalate salt and / or a difluorophosphate.

[In the formula, the inside of the parentheses means that each is a repeating unit. R represents a hydrogen atom, a halogen or a lower alkyl group. R may be all the same, may be different, or may be connected to each other to have an annular structure. ]

The number average molecular weight is preferably 340 to 4000, and more preferably 800 to 3000.

It is preferable that all of the above R are hydrogen atoms.

［式中、括弧の内部はそれぞれが繰り返し単位であることを意味する。Ｒは、水素原子、ハロゲン又は低級アルキル基を表す。Ｒは、全て同一であってもよく、異なっていてもよく、互いに連結して環状構造を有していてもよい。］ In addition, the present invention
(I) Oxalato salt and / or difluorophosphate,
(II) An additive for a non-aqueous electrolyte solution, which is a compound having a repeating unit represented by the following general formula [1] and having a polystyrene-equivalent number average molecular weight of 170 to 5000.
(III) Non-aqueous organic solvent and
(IV) A non-aqueous electrolyte solution containing a solute.

[In the formula, the inside of the parentheses means that each is a repeating unit. R represents a hydrogen atom, a halogen or a lower alkyl group. R may be all the same, may be different, or may be connected to each other to have an annular structure. ]

In the non-aqueous electrolyte solution, the number average molecular weight is preferably 340 to 4000, and more preferably 800 to 3000.

In the non-aqueous electrolyte solution, it is preferable that all of the R are hydrogen atoms.

The content of (II) is preferably 0.03 to 14.0% by mass with respect to 100% by mass of the total amount of (I), (II), (III) and (IV).

Existing in the above electrolyte
The total amount of monomers corresponding to the repeating unit represented by the above general formula [1] (hereinafter referred to as (M)) and
The total amount of the additive for non-aqueous electrolyte solution (monomer equivalent, hereinafter referred to as (P)) is
(M) / (P) = 0 to 0.05 (mass ratio)
Is preferable.

The oxalate salt comprises bis (oxalate) oxalate, difluoro (oxalate) oxalate, tris (oxalate) phosphate, difluorobis (oxalate) phosphate, and tetrafluoro (oxalate) phosphate. It is preferably at least one selected from the group.

The solutes are lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), bis (trifluoromethanesulfonyl) imidelithium (LiN (CF ₃ SO ₂ ) ₂ ), and bis (pentafluoroethanesulfonyl). Consists of imidelithium (LiN (C ₂ F ₅ SO ₂ ) ₂ ), bis (fluorosulfonyl) imidelithium (LiN (FSO ₂ ) ₂ ), and bis (difluorophosphonyl) imidelithium (LiN (POF ₂ ) ₂ ) It is preferably at least one selected from the group.

Further, it is preferable that the electrolytic solution (I) contains at least lithium difluorobis (oxalate) phosphate and lithium difluorophosphate as (I).

It is preferable that the non-aqueous solvent is at least one selected from the group consisting of cyclic carbonates, chain carbonates, cyclic esters, chain esters, cyclic ethers, chain ethers, sulfone compounds, sulfoxide compounds, and ionic liquids. ..

In addition, the above electrolyte solution
Ionic complex with cyclic structure, salt with imide anion, Si-containing compound, sulfuric acid ester compound, phosphoric acid ester compound, cyclic carbonate compound, isocyanate compound, cyclic acetal compound, cyclic acid anhydride, cyclic phosphazene compound, aromatic compound At least one compound selected from the group consisting of
It is preferable to further contain it.

Further, the present invention is a non-aqueous electrolyte secondary battery including at least a positive electrode, a negative electrode, and the non-aqueous electrolyte solution according to any one of the above.

According to the present invention, by adding an oxalate salt and / or difluorophosphate to a non-aqueous electrolyte solution, the cycle characteristics and rate characteristics can be exhibited in a well-balanced manner when used in a non-aqueous electrolyte solution secondary battery. It is possible to provide an additive for a non-aqueous electrolyte solution that can be used.
Further, it is possible to provide a non-aqueous electrolyte solution that can exhibit cycle characteristics and rate characteristics in a well-balanced manner when used in a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery.

Hereinafter, the present invention will be described in detail, but the description of the constituent requirements described below is an example of an embodiment of the present invention, and the specific contents thereof are not limited. It can be modified in various ways within the scope of the gist.

［式中、括弧の内部はそれぞれが繰り返し単位であることを意味する。Ｒは、水素原子、ハロゲン又は低級アルキル基を表す。Ｒは、全て同一であってもよく、異なっていてもよく、共有結合により互いに連結して環状構造を有していてもよい。］ 1. 1. Additives for non-aqueous electrolyte solutions The additives for non-aqueous electrolyte solutions of the present invention are
It is a compound having a repeating unit represented by the following general formula [1].
The polystyrene-equivalent number average molecular weight is 170-5000.
It is an additive for a non-aqueous electrolyte solution to be contained in a non-aqueous electrolyte solution containing an oxalate salt and / or a difluorophosphate.

[In the formula, the inside of the parentheses means that each is a repeating unit. R represents a hydrogen atom, a halogen or a lower alkyl group. The Rs may all be the same or different, and may be covalently linked to each other to have a cyclic structure. ]

The additive for a non-aqueous electrolyte solution of the present invention contains a repeating unit oligomer represented by the above general formula [1] as a main component. A monomer corresponding to the above general formula [1] may also be contained, but the content thereof may be smaller from the viewpoint of cycle characteristics and / or rate characteristics. The additive for a non-aqueous electrolyte solution of the present invention is more preferably composed of an oligomer having a repeating unit represented by the above general formula [1].
It is important that the polystyrene-equivalent number average molecular weight of the non-aqueous electrolyte solution additive is 170 to 5000.
By being a compound having a repeating unit represented by the general formula [1] and having the number average molecular weight, the cycle characteristics and the rate characteristics are exhibited in a well-balanced manner when used in a non-aqueous electrolyte secondary battery. It is possible to obtain an additive for a non-aqueous electrolyte solution that can be used. From the viewpoint of cycle characteristics and / or rate characteristics, the number average molecular weight is preferably 340 to 4000, more preferably 800 to 3000, and particularly preferably 1000 to 2500.

R in the above general formula [1] is a hydrogen atom, a halogen or a lower alkyl group. Examples of the halogen include a fluorine atom, a chlorine atom and a bromine atom, and examples of the lower alkyl group include a methyl group, an ethyl group and a propyl group. From the viewpoint of chemical and electrochemical stability and industrial availability, R is preferably a hydrogen atom.

The non-aqueous electrolyte solution additive is obtained by pre-polymerizing the corresponding monomer. The polymerization method is not particularly limited as long as it is a generally used method, but it can be polymerized by a radical polymerization method, a photopolymerization method, or the like. Of these, radical polymerization is particularly preferable.

The radical polymerization is carried out by a known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization in the presence of a radical polymerization initiator or a radical polymerization source, and is either batch type, semi-continuous type or continuous type. It can be carried out by operation.

The radical initiator is not particularly limited, and examples thereof include azo compounds, peroxide compounds, and redox compounds. For example, 2,2'-azobis (isobutyric acid) dimethyl, azobisisobutyronitrile, t-butylperoxypivalate, di-t-butyl peroxide, i-butylyl peroxide, lauroyl peroxide, succinate peroxide. , Dicinnamylperoxide, di-n-propylperoxydicarbonate, t-butylperoxyallyl monocarbonate, benzoyl peroxide, hydrogen peroxide or ammonium persulfate are preferably used.

The reactor used in the polymerization reaction for obtaining the polymer represented by the general formula [1] is not particularly limited. Moreover, you may use a polymerization solvent in a polymerization reaction. The polymerization solvent is preferably one that does not inhibit radical polymerization, and is an ester solvent such as ethyl acetate, n-butyl acetate, a ketone solvent such as acetone, methyl isobutyl ketone, and a hydrocarbon solvent such as toluene, cyclohexane, and apron. Examples of the sex polar solvent include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like. Further, in the polymerization reaction, the reaction temperature is appropriately selected depending on the radical initiator or the radical initiator, and is preferably in the range of 20 to 200 ° C, more preferably 30 to 140 ° C. Further, the polymer obtained by the polymerization reaction may be reprecipitated and purified using a poor solvent, if necessary. By removing the monomer by purification such as reprecipitation, an additive for a non-aqueous electrolyte solution, which is substantially composed of a repeating unit oligomer represented by the above general formula [1], can be obtained.

2. Non-aqueous electrolyte solution The non-aqueous electrolyte solution of the present invention is
(I) Oxalato salt and / or difluorophosphate,
(II) An additive for a non-aqueous electrolyte solution, which is a compound having a repeating unit represented by the above general formula [1] and having a polystyrene-equivalent number average molecular weight of 170 to 5000.
(III) Non-aqueous organic solvent and
(IV) A non-aqueous electrolyte solution containing a solute.

[(I) Oxalate salt]
The complex is not particularly limited as long as it is a complex in which an oxalate ion is coordinated with the central element. For example, bis (oxalate) borate, difluoro (oxalate) borate, tris (oxalate) phosphate, difluorobis (oxalate) Phosphate, tetrafluoro (oxalate) phosphate and the like can be mentioned.
Above all, from the viewpoint of exhibiting excellent cycle characteristics while preventing the amount of gas generated from becoming too large, bis (oxalate) borate, difluoro (oxalate) borate, difluorobis (oxalate) phosphate, and , At least one selected from the group consisting of tetrafluoro (oxalate) phosphate is preferred.
In addition, bis (oxalate) bolate and difluoro (oxalate) bolate may be used in combination, bis (oxalate) bolate and tris (oxalate) phosphate may be used in combination, or bis (oxalate) Oxalato) borate and difluorobis (oxalate) phosphate may be used in combination, bis (oxalat) borate and tetrafluoro (oxalat) phosphate may be used in combination, or difluoro (oxalate) A borate and tris (oxalate) phosphate may be used in combination, a difluoro (oxalate) bolate and a difluorobis (oxalat) phosphate may be used in combination, or a difluoro (oxalate) bolate may be used in combination. And tetrafluoro (oxalat) phosphate may be used in combination, tris (oxalat) phosphate and difluorobis (oxalat) phosphate may be used in combination, or tris (oxalat) phosphate and tetra. Fluoro (oxalat) phosphate may be used in combination, bis (oxalat) borate, difluoro (oxalat) bolate and tris (oxalat) phosphate may be used in combination, or bis (oxalat). Borate, difluoro (oxalate) borate and difluorobis (oxalate) phosphate may be used in combination, or bis (oxalate) borate, difluoro (oxalate) borate and tetrafluoro (oxalat) phosphorus. A bis (oxalate) phosphate, a tris (oxalate) phosphate, and a difluorobis (oxalate) phosphate may be used in combination, or a bis (oxalate) phosphate may be used in combination. Tris (oxalat) phosphate and tetrafluoro (oxalat) phosphate may be used in combination, or bis (oxalate) phosphate, difluorobis (oxalat) phosphate and tetrafluoro (oxalat) phosphate. Difluoro (oxalate) phosphate and tris (oxalat) phosphate and difluorobis (oxalat) phosphate may be used in combination, or difluoro (oxalat) borate and tris (oxalat) may be used in combination. ) Phosphate and tetrafluoro (oxalat) phosphate may be used in combination, or tris (oxalat) phosphate, difluorobis (oxalat) phosphate and tetrafluoro (oxalat) phosphate may be used in combination. Alternatively, use bis (oxalate) phosphate, difluoro (oxalate) phosphate, tris (oxalat) phosphate, difluorobis (oxalat) phosphate, and tetrafluoro (oxalat) phosphate in combination. May be good.

When the content of (I) is 0.01 to 10.0% by mass with respect to 100% by mass of the total amount of (I), (II), (III), and (IV), the non-aqueous electrolyte secondary battery When used, it is preferable because it is easy to exhibit cycle characteristics and rate characteristics in a well-balanced manner. From the viewpoint of cycle characteristics and / or rate characteristics, the content of (I) is more preferably 0.05 to 5.0% by mass.

When both the oxalate salt and the difluorophosphate are contained, a lithium salt is preferable, and the oxalate salt includes lithium bis (oxalate) borate, difluoro (oxalate) lithium borate, and difluorobis (oxalate). ) Lithium phosphate and lithium tetrafluoro (oxalate) phosphate are preferred. Therefore, lithium difluorophosphate and lithium bis (oxalate) borate may be used in combination, lithium difluorophosphate and lithium difluoro (oxalate) borate may be used in combination, and lithium difluorophosphate and difluorobis (oxalate) may be used in combination. ) Lithium phosphate may be used in combination, lithium difluorophosphate and lithium tetrafluoro (oxalat) may be used in combination, lithium difluorophosphate and lithium bis (oxalate) borate and difluoro (oxalat). Lithium borate may be used in combination, lithium difluorophosphate and bis (oxalat) borate and lithium difluorobis (oxalat) may be used in combination, and lithium difluorophosphate and bis (oxalat) borate may be used in combination. Lithium acid and lithium tetrafluoro (oxalat) phosphate may be used in combination, lithium difluorophosphate and lithium difluoro (oxalat) borate and lithium difluorobis (oxalate) phosphate may be used in combination, or difluorophosphorus. Lithium acid, lithium difluoro (oxalate) borate and lithium tetrafluoro (oxalate) phosphate may be used in combination, or lithium difluorophosphate, lithium difluorobis (oxalat) and lithium tetrafluoro (oxalat) phosphate may be used. Lithium difluorophosphate, lithium bis (oxalate) borate, lithium difluoro (oxalate) borate and lithium difluorobis (oxalate) may be used in combination, or lithium difluorophosphate and bis. Lithium (oxalate) borate, difluoro (oxalate) lithium borate and lithium tetrafluoro (oxalat) phosphate may be used in combination, or lithium difluorophosphate, lithium difluoro (oxalat) borate and difluorobis (oxalat) phosphorus. Lithium acid and lithium tetrafluoro (oxalat) phosphate may be used in combination, or lithium difluorophosphate, lithium bis (oxalat) borate, lithium difluoro (oxalat) borate, lithium difluorobis (oxalat) and tetra. Fluoro (oxalat) lithium phosphate may be used in combination.
In particular, it is preferable that the electrolytic solution (I) contains at least lithium difluorobis (oxalate) phosphate and lithium difluorophosphate as (I). In that case, the content of lithium difluorobis (oxalate) phosphate is 0.15 to 2.50% by mass with respect to 100% by mass of the total amount of (I), (II), (III) and (IV). , The content of lithium difluorophosphate is particularly preferably 0.3 to 3.0% by mass.

[(II) Additives for non-aqueous electrolyte solutions]
The non-aqueous electrolyte solution of the present invention contains the above-mentioned additive for non-aqueous electrolyte solution. When the content of (II) is 0.03 to 14.0% by mass with respect to 100% by mass of the total amount of (I), (II), (III), and (IV), the non-aqueous electrolyte secondary battery When used, it is preferable because it is easy to exhibit cycle characteristics and rate characteristics in a well-balanced manner. From the viewpoint of cycle characteristics and / or rate characteristics, the content of (II) is more preferably 0.07 to 12.0% by mass.

[(III) Non-aqueous organic solvent]
If a non-aqueous solvent is used, the non-aqueous electrolyte solution is generally called a non-aqueous electrolyte solution, and if a polymer is used, it is called a polymer solid electrolyte. Polymer solid electrolytes also include those containing a non-aqueous solvent as a plasticizer.

The non-aqueous organic solvent (III) is not particularly limited as long as it is an aprotonic solvent capable of dissolving (I), (II), and (IV) of the present invention. Esters, ethers, lactones, nitriles, imides, sulfones and the like can be used. Moreover, not only a single solvent but also two or more kinds of mixed solvents may be used. Specific examples include ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl butyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4, 5-Difluoroethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl 2-fluoropropionate, ethyl 2-fluoropropionate, diethyl ether , Ethylene, Propionitrile, tetrahydrofuran, 2-Methyl tetrahydrofuran, furan, tetrahydropyrane, 1,3-dioxane, 1,4-dioxane, dibutyl ether, diisopropyl ether, 1,2-dimethoxyethane, N, N-dimethylformamide , Dimethylsulfoxide, sulfolane, γ-butyrolactone, γ-valerolactone and the like.

The polymer used to obtain the polymer solid electrolyte is not particularly limited as long as it is an aprotic polymer capable of dissolving (I), (II) and (IV). Examples thereof include polymers having polyethylene oxide in the main chain or side chains, homopolymers or copolymers of polyvinylidene fluoride, methacrylic acid ester polymers, polyacrylonitrile and the like. When adding a plasticizer to these polymers, the above-mentioned aprotic non-aqueous solvent can be used.

[(IV) Solute]
The solute is not particularly limited, and a salt consisting of any cation-anion pair can be used. Specific examples include alkali metal ions such as lithium ion and sodium ion, alkaline earth metal ions, and quaternary ammonium as cations, and hexafluorophosphate, tetrafluoroboric acid, and perchloric acid as anions. , Hexafluorohydric acid, hexafluoroantimonic acid, trifluoromethanesulfonic acid, bis (trifluoromethanesulfonyl) imide, bis (pentafluoroethanesulfonyl) imide, (trifluoromethanesulfonyl) (pentafluoroethanesulfonyl) imide, bis (fluorosulfonyl) ) Imide, (trifluoromethanesulfonyl) (fluorosulfonyl) imide, (pentafluoroethanesulfonyl) (fluorosulfonyl) imide, tris (trifluoromethanesulfonyl) methide, bis (difluorophosphonyl) imide, (difluorophosphonyl) (fluorosulfonyl) ) Imide and the like. One type of these solutes may be used alone, or two or more types may be mixed and used in any combination and ratio according to the intended use. Among them, considering the energy density, output characteristics, life, etc. of the battery, the cation is preferably at least one selected from the group consisting of lithium, sodium, magnesium, and quaternary ammonium, and the anions are hexafluorophosphoric acid and tetra. From the group consisting of fluoroboric acid, bis (trifluoromethanesulfonyl) imide, bis (pentafluoroethanesulfonyl) imide, bis (fluorosulfonyl) imide, bis (difluorophosphonyl) imide, (difluorophosphonyl) (fluorosulfonyl) imide At least one selected is preferred.
In particular, lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), bis (trifluoromethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) ₂ ), bis (pentafluoroethanesulfonyl) imide lithium. From the group consisting of (LiN (C ₂ F ₅ SO ₂ ) ₂ ), bis (fluorosulfonyl) imide lithium (LiN (FSO ₂ ) ₂ ), and bis (difluorophosphonyl) imide lithium (LiN (POF ₂ ) ₂ ). At least one selected is preferred.

The total amount of (IV) (hereinafter referred to as “solute concentration”) with respect to 100% by mass of the total amount of (I), (II), (III), and (IV) is not particularly limited, but the lower limit is 0. It is 5 mol / L or more, preferably 0.7 mol / L or more, more preferably 0.9 mol / L or more, and the upper limit is 5.0 mol / L or less, preferably 4.0 mol / L or less, further preferably 2. The range is 0.0 mol / L or less. If it is less than 0.5 mol / L, the ionic conductivity is lowered and the cycle characteristics and output characteristics of the non-aqueous electrolyte secondary battery are lowered. On the other hand, if it exceeds 5.0 mol / L, the viscosity of the non-aqueous electrolyte solution is increased. If it rises, the ionic conduction is also lowered, and the cycle characteristics and output characteristics of the non-aqueous electrolyte secondary battery may be lowered.

（一般式［２］において、
Ａは金属イオン、プロトン及びオニウムイオンからなる群から選ばれる少なくとも１つであり、
Ｆはフッ素であり、
Ｍは１３族元素（Ａｌ、Ｂ）、１４族元素（Ｓｉ）及び１５族元素（Ｐ、Ａｓ、Ｓｂ）からなる群から選ばれる少なくとも１つであり、
Ｏは酸素であり、
Ｓは硫黄である。
Ｒ^１は炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基（炭素数が３以上の場合にあっては、分岐鎖あるいは環状構造のものも使用できる）、又は−Ｎ（Ｒ^２）−を表す。このとき、Ｒ^２は水素、アルカリ金属、炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基を表す。炭素数が３以上の場合にあっては、Ｒ^２は分岐鎖あるいは環状構造をとることもできる。
Ｙは炭素又は硫黄である。Ｙが炭素である場合、ｒは１である。Ｙが硫黄である場合、ｒは１又は２である。
ａは１又は２、ｏは２又は４、ｎは１又は２、ｐは０又は１、ｑは１又は２、ｒは０、１又は２である。ｐが０の場合、Ｓ−Ｙ間に直接結合を形成する。）

（一般式［３］において、
Ａは金属イオン、プロトン及びオニウムイオンからなる群から選ばれる少なくとも１つであり、
Ｆはフッ素であり、
Ｍは１３族元素（Ａｌ、Ｂ）、１４族元素（Ｓｉ）、及び１５族元素（Ｐ、Ａｓ、Ｓｂ）からなる群から選ばれる少なくとも１つであり、
Ｏは酸素であり、
Ｎは窒素である。
Ｙは炭素又は硫黄であり、Ｙが炭素である場合、ｑは１であり、Ｙが硫黄である場合、ｑは１又は２である。
Ｒ^１は炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基（炭素数が３以上の場合にあっては、分岐鎖あるいは環状構造のものも使用できる）、又は−Ｎ（Ｒ^２）−を表す。このとき、Ｒ^２は水素、アルカリ金属、炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基を表す。炭素数が３以上の場合にあっては、Ｒ^２は分岐鎖あるいは環状構造をとることもできる。
Ｒ^３は水素、炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基（炭素数が３以上の場合にあっては、分岐鎖あるいは環状構造のものも使用できる）、又は−Ｎ（Ｒ^２）−を表す。このとき、Ｒ^２は水素、アルカリ金属、炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基を表す。炭素数が３以上の場合にあっては、Ｒ^２は分岐鎖あるいは環状構造をとることもできる。
ａは１又は２、ｏは２又は４、ｎは１又は２、ｐは０又は１、ｑは１又は２、ｒは０又は１である。ｐが０の場合、Ｒ^１の両隣に位置する原子同士（すなわちＹと炭素原子）が直接結合を形成する。ｒが０の場合Ｍ−Ｎ間に直接結合を形成する。）

（一般式［４］において、
Ｄはハロゲンイオン、ヘキサフルオロリン酸アニオン、テトラフルオロホウ酸アニオン、ビス（トリフルオロメタンスルホニル）イミドアニオン、ビス（フルオロスルホニル）イミドアニオン、（フルオロスルホニル）（トリフルオロメタンスルホニル）イミドアニオン、ビス（ジフルオロホスホニル）イミドアニオンから選ばれる少なくとも一つであり、
Ｆはフッ素であり、
Ｍは１３族元素（Ａｌ、Ｂ）、１４族元素（Ｓｉ）及び１５族元素（Ｐ、Ａｓ、Ｓｂ）からなる群から選ばれるいずれか１つであり
Ｏは酸素であり、
Ｎは窒素である。
Ｙは炭素又は硫黄であり、Ｙが炭素である場合ｑは１であり、Ｙが硫黄である場合ｑは１又は２である。
Ｘは炭素又は硫黄であり、Ｘが炭素である場合ｒは１であり、Ｘが硫黄である場合ｒは１又は２である。
Ｒ^１は炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基（炭素数が３以上の場合にあっては、分岐鎖あるいは環状構造のものも使用できる）、又は−Ｎ（Ｒ^２）−を表す。このとき、Ｒ^２は水素、アルカリ金属、炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基を表す。炭素数が３以上の場合にあっては、Ｒ^２は分岐鎖あるいは環状構造をとることもできる。
Ｒ^４、Ｒ^５はそれぞれ独立で炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基であり、炭素数が３以上の場合にあっては、分岐鎖あるいは環状構造のものも使用できる。また、下記一般式［５］の様にお互いを含む環状構造を有しても良い。

ｃは０又は１であり、ｎが１の場合、ｃは０（ｃが０のときＤは存在しない）であり、ｎが２の場合、ｃは１となる。
ｏは２又は４、ｎは１又は２、ｐは０又は１、ｑは１又は２、ｒは１又は２、ｓは０又は１である。ｐが０の場合、Ｙ−Ｘ間に直接結合を形成する。
ｓが０の場合、Ｎ（Ｒ^４）（Ｒ^５）とＲ^１は直接結合し、その際は下記の［６］〜［９］のような構造をとることもできる。直接結合が二重結合となる［７］、［９］の場合、Ｒ^５は存在しない。また［８］の様に二重結合が環の外に出た構造を取ることも出来る。この場合のＲ^６、Ｒ^７はそれぞれ独立で水素、又は炭素数１〜１０の環やヘテロ原子やハロゲン原子を有していてもよい炭化水素基であり、炭素数が３以上の場合にあっては、分岐鎖あるいは環状構造のものも使用できる。）

上記イミドアニオンを有する塩としては、下記一般式［１０］〜［１６］で示される化合物や、（ＣＦ_２）_２（ＳＯ_２）_２Ｎ⁻、（ＣＦ_２）_３（ＳＯ_２）_２Ｎ⁻等の環状アルキレン鎖含有アニオンを有する塩を例示することができる。

［一般式［１０］〜［１１］及び［１３］〜［１５］中、Ｒ^８〜Ｒ^１１はそれぞれ互いに独立して、フッ素原子、炭素数が１〜１０の直鎖あるいは分岐状のアルコキシ基、炭素数が２〜１０のアルケニルオキシ基、炭素数が２〜１０のアルキニルオキシ基、炭素数が３〜１０の、シクロアルコキシ基、シクロアルケニルオキシ基、及び、炭素数が６〜１０のアリールオキシ基から選ばれる有機基であり、その有機基中にフッ素原子、酸素原子、不飽和結合が存在することもできる。一般式［１１］、［１２］、［１５］及び［１６］中、Ｘ^２及びＸ^３はそれぞれ互いに独立して、フッ素原子、炭素数が１〜１０の直鎖あるいは分岐状のアルキル基、炭素数が２〜１０のアルケニル基、炭素数が２〜１０のアルキニル基、炭素数が３〜１０の、シクロアルキル基、シクロアルケニル基、炭素数が６〜１０のアリール基、炭素数が１〜１０の直鎖あるいは分岐状のアルコキシ基、炭素数が２〜１０のアルケニルオキシ基、炭素数が２〜１０のアルキニルオキシ基、炭素数が３〜１０の、シクロアルコキシ基、シクロアルケニルオキシ基、及び、炭素数が６〜１０のアリールオキシ基から選ばれる有機基であり、その有機基中にフッ素原子、酸素原子、不飽和結合が存在することもできる。また、一般式［１０］〜［１６］中には少なくとも一つのＰ−Ｆ結合及び／又はＳ−Ｆ結合を含む。Ｍ^２、Ｍ^３はそれぞれ互いに独立して、プロトン、金属カチオン又はオニウムカチオンである。］
上記Ｓｉ含有化合物としては、下記一般式［１７］で示される少なくとも１種の化合物や、ヘキサメチルシロキサン、１，３−ジビニルテトラメチルジシロキサン、（ビスヘキサフルオロイソプロポキシ）（ジメチル）（ジビニル）ジシロキサン、テトラメチルシラン、トリメチルビニルシラン、ビニルジメチルフルオロシラン、ジビニルメチルフルオロシラン等を例示することができる。
Ｓｉ（Ｒ^１２）_ｘ（Ｒ^１３）_４−ｘ ［１７］
［一般式［１７］中、Ｒ^１２はそれぞれ互いに独立して炭素−炭素不飽和結合を有する基を表す。Ｒ^１３はそれぞれ互いに独立して、フッ素原子、アルキル基、アルコキシ基、アルケニル基、アルケニルオキシ基、アルキニル基、アルキニルオキシ基、アリール基、及びアリールオキシ基からなる群から選ばれる基を示し、これらの基はフッ素原子及び／又は酸素原子を有していても良い。ｘは２〜４である。］
上記硫酸エステル化合物としては、下記一般式［１８］、［１９］、及び［２０］で示される環状スルホン酸化合物や、２，２−ジオキシド−１，２−オキサチオラン−４−イル、１，３−プロパンスルトン、１，３−ブタンスルトン、１，４−ブタンスルトン等を例示することができる。

（式［１８］中、Ｏは酸素原子、Ｓは硫黄原子、ｎ^２は１以上３以下の整数である。また、Ｒ^１４、Ｒ^１５、Ｒ^１６、Ｒ^１７は、それぞれ独立して水素原子、置換若しくは無置換の炭素数１以上５以下のアルキル基、又は置換若しくは無置換の炭素数１以上４以下のフルオロアルキル基である。）

（式［１９］中、Ｏは酸素原子、Ｓは硫黄原子、ｎ^３は０以上４以下の整数であり、Ｒ^１８、Ｒ^１９は、それぞれ独立して水素原子、ハロゲン原子、又は置換若しくは無置換の炭素数１以上５以下のアルキル基であり、Ｒ^２０、Ｒ^２１は、それぞれ独立して水素原子、ハロゲン原子、置換若しくは無置換の炭素数１〜５のアルキル基、又は置換若しくは無置換の炭素数１以上４以下のフルオロアルキル基であり、ｎ^４は０以上４以下の整数である。）

（式［２０］中、Ｏは酸素原子、Ｓは硫黄原子、ｎ^５は０〜３の整数であり、Ｒ^２２、Ｒ^２３は、それぞれ独立して水素原子、ハロゲン原子、置換若しくは無置換の炭素数１以上５以下のアルキル基、又は置換若しくは無置換の炭素数１以上４以下のフルオロアルキル基である。）
上記リン酸エステル化合物としては、リン酸トリメチル、リン酸トリブチル、及びリン酸トリオクチル、リン酸トリス（２，２，２−トリフルオロエチル）、モノフルオロプロパギロキシリン酸-五フッ化リン酸リチウム等を例示することができる。
上記環状カーボネート化合物としては、下記一般式［２１］で示される環状カーボネート化合物や、ジメチルビニレンカーボネート等を例示することができる。

（式［２１］中、Ｏは酸素原子、Ａは炭素数１０以下の、不飽和結合や環状構造やハロゲンを有してもよい炭化水素であり、Ｂは炭素数１０以下の、不飽和結合や環状構造やハロゲンを有してもよい炭化水素である。なお、Ａ−Ｂ間に二重結合を有してもよい。）
上記イソシアネート化合物としては、ヘキサメチレンジイソシアネート、オクタメチレンジイソシアネート、２−イソシアナトエチルアクリレート、２−イソシアナトエチルメタクリレート等を例示することができる。
上記環状アセタール化合物としては、１，３−ジオキソラン、１，３−ジオキサン、１，３，５−トリオキサン等を例示することができる。
上記環状酸無水物としては、無水コハク酸、無水マレイン酸等を例示することができる。
上記環状ホスファゼン化合物としては、メトキシペンタフルオロシクロトリホスファゼン、エトキシペンタフルオロシクロトリホスファゼン、フェノキシペンタフルオロシクロトリホスファゼン、ジエトキシペンタフルオロシクロトリホスファゼン、エトキシヘプタフルオロシクロテトラホスファゼン等を例示することができる。
上記芳香族化合物としては、シクロヘキシルベンゼン、ビフェニル、ｔｅｒｔ−ブチルベンゼン、４−フルオロビフェニル、フルオロベンゼン、２，４−ジフルオロベンゼン、ジフルオロアニソール等を例示することができる。
なお、その他の成分として上記で挙げた添加剤の一部は（ＩＶ）溶質と重複するものがあるが、そのような化合物は、（ＩＶ）溶質のように比較的多く含有させて用いることもできるし、添加剤（その他の成分）のように比較的少なく含有させて用いることもできる。 [About other ingredients]
Furthermore, additives generally used for the non-aqueous electrolyte solution of the present invention may be added at an arbitrary ratio as long as the gist of the present invention is not impaired. Specific examples thereof include compounds having an overcharge prevention effect, a negative electrode film forming effect, and a positive electrode protection effect such as cyclohexylbenzene, biphenyl, t-butylbenzene, vinyl ethylene carbonate, and difluoroanisole. Further, it is also possible to use the non-aqueous electrolyte solution as a pseudo-solid by a gelling agent or a crosslinked polymer, as in the case of being used in a non-aqueous electrolyte secondary battery called a polymer battery.
Further, a compound corresponding to the monomer of the additive for the non-aqueous electrolyte solution of the present invention may also be present in the non-aqueous electrolyte solution. At this time, it is present in the electrolytic solution.
The total amount (M) of the monomers corresponding to the repeating unit represented by the above general formula [1] and
The total amount (P) (monomer equivalent) of the above-mentioned additive for non-aqueous electrolyte solution is
(M) / (P) = 0 to 0.05 (mass ratio)
Is preferable because it leads to improvement of rate characteristics. (M) / (P) = 0 to 0.02 is more preferable, and (M) / (P) = 0 is even more preferable. The total amount (M) of the monomer and the total amount (P) (monomer equivalent) of the additive for the non-aqueous electrolyte solution in the non-aqueous electrolyte solution are ^{calculated from the 1} H-NMR measurement result.
Further, the non-aqueous electrolyte solution of the present invention is
Ionic complex with cyclic structure, salt with imide anion, Si-containing compound, sulfate ester compound, phosphoric acid ester compound, cyclic carbonate compound, isocyanate compound, cyclic acetal compound, cyclic acid anhydride, cyclic phosphazene compound, aromatic compound It is preferable to contain at least one compound selected from the group consisting of (hereinafter collectively referred to as "second additive").
The content of (II) is preferably 0.03 to 14.0% by mass with respect to 100% by mass of the total amount of the above (I), (II), (III), (IV) and the second additive. More preferably 0.07 to 12.0% by mass.
The total amount of (IV) with respect to 100% by mass of the total amount of the above (I), (II), (III), (IV) and the second additive is not particularly limited, but the lower limit is 0.5 mol / L or more. It is preferably 0.7 mol / L or more, more preferably 0.9 mol / L or more, and the upper limit is 5.0 mol / L or less, preferably 4.0 mol / L or less, still more preferably 2.0 mol / L or less. Is the range of.
The total amount of the second additive is not particularly limited, but is 0.01 to 20.0% by mass with respect to 100% by mass of the total amount of the above (I), (II), (III), (IV) and the second additive. %, More preferably 0.05 to 10.0% by mass.
Examples of the ionic complex having a cyclic structure include compounds represented by the following general formulas [2] to [4].

(In the general formula [2]
A is at least one selected from the group consisting of metal ions, protons and onium ions.
F is fluorine,
M is at least one selected from the group consisting of Group 13 elements (Al, B), Group 14 elements (Si) and Group 15 elements (P, As, Sb).
O is oxygen,
S is sulfur.
R ¹ may have a ring having 1 to 10 carbon atoms, a hetero atom or a halogen atom (in the case of 3 or more carbon atoms, a branched chain or a cyclic structure can also be used). , Or −N (R ² ) −. At this time, R ² represents hydrogen, an alkali metal, a ring having 1 to 10 carbon atoms, a hetero atom, or a hydrocarbon group which may have a halogen atom. When the number of carbon atoms is 3 or more, R ² may have a branched chain or a cyclic structure.
Y is carbon or sulfur. If Y is carbon, then r is 1. If Y is sulfur, r is 1 or 2.
a is 1 or 2, o is 2 or 4, n is 1 or 2, p is 0 or 1, q is 1 or 2, r is 0, 1 or 2. When p is 0, a direct bond is formed between SY. )

(In the general formula [3]
A is at least one selected from the group consisting of metal ions, protons and onium ions.
F is fluorine,
M is at least one selected from the group consisting of Group 13 elements (Al, B), Group 14 elements (Si), and Group 15 elements (P, As, Sb).
O is oxygen,
N is nitrogen.
If Y is carbon or sulfur, q is 1 if Y is carbon, and q is 1 or 2 if Y is sulfur.
R ¹ may have a ring having 1 to 10 carbon atoms, a hetero atom or a halogen atom (in the case of 3 or more carbon atoms, a branched chain or a cyclic structure can also be used). , Or −N (R ² ) −. At this time, R ² represents hydrogen, an alkali metal, a ring having 1 to 10 carbon atoms, a hetero atom, or a hydrocarbon group which may have a halogen atom. When the number of carbon atoms is 3 or more, R ² may have a branched chain or a cyclic structure.
R ³ is a hydrocarbon group having hydrogen, a ring having 1 to 10 carbon atoms, a hetero atom or a halogen atom (in the case of 3 or more carbon atoms, a branched chain or a cyclic structure is also used. Can be), or -N (R ² )-represents. At this time, R ² represents hydrogen, an alkali metal, a ring having 1 to 10 carbon atoms, a hetero atom, or a hydrocarbon group which may have a halogen atom. When the number of carbon atoms is 3 or more, R ² may have a branched chain or a cyclic structure.
a is 1 or 2, o is 2 or 4, n is 1 or 2, p is 0 or 1, q is 1 or 2, and r is 0 or 1. When p is 0, ^{atoms located on both sides of R 1} (that is, Y and a carbon atom) form a direct bond. When r is 0, a direct bond is formed between MN. )

(In the general formula [4],
D is halogen ion, hexafluorophosphate anion, tetrafluoroborate anion, bis (trifluoromethanesulfonyl) imide anion, bis (fluorosulfonyl) imide anion, (fluorosulfonyl) (trifluoromethanesulfonyl) imide anion, bis (difluorophospho). Nyl) At least one selected from imide anions,
F is fluorine,
M is any one selected from the group consisting of Group 13 elements (Al, B), Group 14 elements (Si) and Group 15 elements (P, As, Sb), and O is oxygen.
N is nitrogen.
Y is carbon or sulfur, q is 1 if Y is carbon, and q is 1 or 2 if Y is sulfur.
X is carbon or sulfur, r is 1 if X is carbon, and r is 1 or 2 if X is sulfur.
R ¹ may have a ring having 1 to 10 carbon atoms, a hetero atom or a halogen atom (in the case of 3 or more carbon atoms, a branched chain or a cyclic structure can also be used). , Or −N (R ² ) −. At this time, R ² represents hydrogen, an alkali metal, a ring having 1 to 10 carbon atoms, a hetero atom, or a hydrocarbon group which may have a halogen atom. When the number of carbon atoms is 3 or more, R ² may have a branched chain or a cyclic structure.
R ⁴ and R ⁵ are hydrocarbon groups that may independently have a ring having 1 to 10 carbon atoms, a hetero atom, or a halogen atom, and in the case of 3 or more carbon atoms, a branched chain or a branched chain or An annular structure can also be used. Further, it may have an annular structure including each other as in the following general formula [5].

When c is 0 or 1, when n is 1, c is 0 (when c is 0, D does not exist), and when n is 2, c is 1.
o is 2 or 4, n is 1 or 2, p is 0 or 1, q is 1 or 2, r is 1 or 2, and s is 0 or 1. When p is 0, a direct bond is formed between Y and X.
When s is 0, N (R ⁴ ) (R ⁵ ) and R ¹ are directly bonded, and in that case, the following structures [6] to [9] can be adopted. In the case of [7] and [9] in which the direct bond becomes a double bond, R ⁵ does not exist. It is also possible to take a structure in which the double bond goes out of the ring as in [8]. In this case, R ⁶ and R ⁷ are each independently hydrogen, or a hydrocarbon group which may have a ring having 1 to 10 carbon atoms, a hetero atom, or a halogen atom, and may have 3 or more carbon atoms. Alternatively, a branched chain or a cyclic structure can be used. )

Examples of the salt having an imide anion include compounds represented by the following general formulas [10] to [16], (CF ₂ ) ₂ (SO ₂ ) ₂ N ⁻ , and (CF ₂ ) ₃ (SO ₂ ) ₂ N ^−. Examples of salts having a cyclic alkylene chain-containing anion such as the above can be exemplified.

[In the general formulas [10] to [11] and [13] to [15], R ^{8 to} R ¹¹ are independent of each other and are linear or branched alkoxy groups having a fluorine atom and 1 to 10 carbon atoms. , An alkenyloxy group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkoxyoxy group, and an aryl having 6 to 10 carbon atoms. It is an organic group selected from oxy groups, and fluorine atoms, oxygen atoms, and unsaturated bonds may be present in the organic groups. In the general formulas [11], [12], [15] and [16], X ² and X ³ are independent of each other and have a fluorine atom and a linear or branched alkyl group having 1 to 10 carbon atoms. An alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group, an aryl group having 6 to 10 carbon atoms, and 1 carbon number. A linear or branched alkoxy group of 10 to 10, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkoxy group and a cycloalkenyloxy group having 3 to 10 carbon atoms. , And an organic group selected from an aryloxy group having 6 to 10 carbon atoms, and a fluorine atom, an oxygen atom, and an unsaturated bond may be present in the organic group. Further, the general formulas [10] to [16] include at least one PF bond and / or SF bond. M ² and M ³ are independent of each other and are protons, metal cations or onium cations. ]
Examples of the Si-containing compound include at least one compound represented by the following general formula [17], hexamethylsiloxane, 1,3-divinyltetramethyldisiloxane, (bishexafluoroisopropoxy) (dimethyl) (divinyl). Examples thereof include disiloxane, tetramethylsilane, trimethylvinylsilane, vinyldimethylfluorosilane, and divinylmethylfluorosilane.
Si (R ¹² ) _x (R ¹³ ) _4-x [17]
[In the general formula [17], R ¹² represents a group having a carbon-carbon unsaturated bond independently of each other. R ¹³ each independently represents a group selected from the group consisting of a fluorine atom, an alkyl group, an alkoxy group, an alkenyl group, an alkenyloxy group, an alkynyl group, an alkynyloxy group, an aryl group, and an aryloxy group. The group of may have a fluorine atom and / or an oxygen atom. x is 2-4. ]
Examples of the sulfate ester compound include cyclic sulfonic acid compounds represented by the following general formulas [18], [19], and [20], 2,2-dioxide-1,2-oxathiolane-4-yl, 1,3. -Propane sulton, 1,3-butane sulton, 1,4-butan sulton and the like can be exemplified.

(In the formula [18], O is an oxygen atom, S is a sulfur atom, and n ² is an integer of 1 or more and 3 or less. Further, R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ are independently hydrogen atoms. , A substituted or unsubstituted alkyl group having 1 or more and 5 or less carbon atoms, or a substituted or unsubstituted fluoroalkyl group having 1 or more and 4 or less carbon atoms.)

(In the formula [19], O is an oxygen atom, S is a sulfur atom, n ³ is an integer of 0 or more and 4 or less, and R ¹⁸ and R ¹⁹ are independently hydrogen atoms, halogen atoms, or substituted or absent. Substituted alkyl groups having 1 to 5 carbon atoms, and R ²⁰ and R ²¹ are independently hydrogen atoms, halogen atoms, substituted or unsubstituted alkyl groups having 1 to 5 carbon atoms, or substituted or unsubstituted alkyl groups, respectively. Is a fluoroalkyl group having 1 or more and 4 or less carbon atoms, and n ⁴ is an integer of 0 or more and 4 or less.)

(In the formula [20], O is an oxygen atom, S is a sulfur atom, n ⁵ is an integer of 0 to 3, and R ²² and R ²³ are independently hydrogen atoms, halogen atoms, substituted or unsubstituted, respectively. An alkyl group having 1 to 5 carbon atoms or a substituted or unsubstituted fluoroalkyl group having 1 to 4 carbon atoms.)
Examples of the phosphate ester compound include trimethyl phosphate, tributyl phosphate, trioctyl phosphate, tris phosphate (2,2,2-trifluoroethyl), and monofluoropropagiloxyphosphate-lithium pentafluorophosphate. Etc. can be exemplified.
Examples of the cyclic carbonate compound include cyclic carbonate compounds represented by the following general formula [21], dimethylvinylene carbonate, and the like.

(In the formula [21], O is an oxygen atom, A is a hydrocarbon having 10 or less carbon atoms and may have an unsaturated bond, a cyclic structure or halogen, and B is an unsaturated bond having 10 or less carbon atoms. It is a hydrocarbon that may have a cyclic structure or a halogen. It may have a double bond between AB.)
Examples of the isocyanate compound include hexamethylene diisocyanate, octamethylene diisocyanate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate.
Examples of the cyclic acetal compound include 1,3-dioxolane, 1,3-dioxane, and 1,3,5-trioxane.
Examples of the cyclic acid anhydride include succinic anhydride and maleic anhydride.
Examples of the cyclic phosphazene compound include methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, diethoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.
Examples of the aromatic compound include cyclohexylbenzene, biphenyl, tert-butylbenzene, 4-fluorobiphenyl, fluorobenzene, 2,4-difluorobenzene, difluoroanisole and the like.
Some of the additives listed above as other components overlap with the (IV) solute, but such compounds may be used in a relatively large amount like the (IV) solute. It can be used, or it can be used by containing it in a relatively small amount like an additive (other component).

3. 3. Non-aqueous electrolyte secondary battery Non-aqueous electrolyte, negative electrode material capable of reversibly inserting and removing alkali metal ions such as lithium ions and sodium ions, or alkaline earth metal ions, and lithium ions and sodium An electrochemical device using a positive electrode material in which alkali metal ions such as ions or alkaline earth metal ions can be reversibly inserted and removed is called a non-aqueous electrolyte secondary battery.
The negative electrode is not particularly limited, but a material capable of reversibly inserting and removing alkali metal ions such as lithium ions and sodium ions or alkaline earth metal ions is used, and the positive electrode is not particularly limited. However, a material is used in which alkali metal ions such as lithium ions and sodium ions, or alkaline earth metal ions can be reversibly inserted and removed.

For example, when the cation is lithium, the negative electrode material is a lithium metal, an alloy of lithium and another metal, an intermetal compound, various carbon materials capable of storing and releasing lithium, metal oxides, metal nitrides, and activated carbon. , Conductive polymer and the like are used. Examples of the carbon material include graphitizable carbon, non-graphitizable carbon (also called hard carbon) having a (002) plane spacing of 0.37 nm or more, and (002) plane spacing of 0. Examples thereof include graphite having a diameter of 37 nm or less, and artificial graphite, natural graphite and the like are used as the latter.

For example, if the cation is _{lithium, LiCoO 2, LiNiO 2, LiMnO} 2, LiMn 2 O lithium-containing transition metal composite oxides such as ₄ as a positive electrode material, those of the lithium-containing transition metal composite oxide Co, Mn, and Ni, etc. that the transition metal is a mixture of a plurality (e.g., LiNi _0.5 Mn _1.5 O _4, etc.), which part of the transition metal of these lithium-containing transition metal composite oxide is substituted with a metal other than other transition metals , Phosphorates of transition metals such _{as LiFePO 4} , LiCoPO ₄ , LiMnPO ₄ called olivine, _{oxides such as TiO 2} , V ₂ O ₅ , MoO ₃ , sulfides such as TiS ₂ , FeS, or polyacetylene, polypara. Conductive polymers such as phenylene, polyaniline, and polypyrrole, activated carbon, radical-generating polymers, carbon materials, and the like are used.

Acetylene black, Ketjen black, carbon fiber, or graphite is added as a conductive material to the positive electrode material and the negative electrode material, and polytetrafluoroethylene, polyvinylidene fluoride, SBR resin, etc. are added as a binder, and the material is further molded into a sheet. The prepared electrode sheet can be used.

As the separator for preventing contact between the positive electrode and the negative electrode, a non-woven fabric or a porous sheet made of polypropylene, polyethylene, paper, glass fiber or the like is used.

From each of the above elements, an electrochemical device having a shape such as a coin shape, a cylinder shape, a square shape, or an aluminum laminated sheet type can be assembled.

In addition, non-aqueous electrolyte secondary batteries are
A non-aqueous electrolyte secondary battery including (a) the above-mentioned non-aqueous electrolyte solution, (b) positive electrode, (c) negative electrode, and (d) separator as described below may be used.
[(A) Positive electrode]
(A) The positive electrode preferably contains at least one oxide and / or polyanion compound as the positive electrode active material.
[Positive electrode active material]
In the case of a lithium ion secondary battery in which the cation in the non-aqueous electrolyte solution is mainly lithium, (a) the positive electrode active material constituting the positive electrode is not particularly limited as long as it is various materials capable of charging and discharging. For example, (A) a lithium transition metal composite oxide containing at least one metal of nickel, manganese, and cobalt and having a layered structure, (B) a lithium manganese composite oxide having a spinel structure, (C). Examples thereof include lithium-containing olivine-type phosphates and (D) those containing at least one of lithium excess layered transition metal oxides having a layered rock salt type structure.
((A) Lithium Transition Metal Composite Oxide)
Positive electrode active material (A) Examples of the lithium transition metal composite oxide containing at least one metal of nickel, manganese, and cobalt and having a layered structure include lithium-cobalt composite oxide and lithium-nickel composite oxide. , Lithium-Nickel-Cobalt Composite Oxide, Lithium-Nickel-Cobalt-Aluminum Composite Oxide, Lithium-Cobalt-Manganese Composite Oxide, Lithium-Nicken-Manganese Composite Oxide, Lithium-Nicken-Manganese-Cobalt Composite Oxide And so on. In addition, some of the transition metal atoms that are the main constituents of these lithium transition metal composite oxides are Al, Ti, V, Cr, Fe, Cu, Zn, Mg, Ga, Zr, Si, B, Ba, Y, Sn. Those substituted with other elements such as may be used.
Specific examples of the lithium-cobalt composite oxide and the lithium-nickel composite oxide include _{lithium cobalt oxide (LiCo 0.98} Mg _{0.) to which different elements such as LiCoO 2} , LiNiO ₂ and Mg, Zr, Al and Ti are added. ₀₁ Zr _0.01 O ₂ , LiCo _0.98 Mg _0.01 Al _0.01 O ₂ , LiCo _0.975 Mg _0.01 Zr _0.005 Al _0.01 O ₂ etc.), WO2014 / 034043 Lithium cobalt oxide or the like in which a rare earth compound is adhered to the described surface may be used. Further, as described in JP-A-2002-151707, _{a part of the particle surface of the LiCoO 2} particle powder coated with aluminum oxide may be used.
The lithium-nickel-cobalt composite oxide and the lithium-nickel-cobalt-aluminum composite oxide are represented by the general formula (1-1).
Li _a Ni _1-bc Co _b M ¹ _c O ₂ (1-1)
In formula (1-1), M ¹ is at least one element selected from the group consisting of Al, Fe, Mg, Zr, Ti, and B, a is 0.9 ≦ a ≦ 1.2, and b. , C satisfy the conditions of 0.1 ≦ b ≦ 0.3 and 0 ≦ c ≦ 0.1.
These can be prepared according to, for example, the production method described in JP-A-2009-137834 and the like. Specifically, LiNi _0.8 Co _0.2 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.87 Co _0.10 Al _0.03 O ₂ , LiNi _0.6. Co _0.3 Al _0.1 O _{2 and the} like can be mentioned.
Specific examples of the lithium-cobalt-manganese composite oxide and the lithium-nickel-manganese composite oxide include LiNi _0.5 Mn _0.5 O ₂ and LiCo _0.5 Mn _0.5 O ₂ .
Examples of the lithium-nickel-manganese-cobalt composite oxide include a lithium-containing composite oxide represented by the general formula (1-2).
_{Li d Ni e Mn f Co g} M 2 h O 2 (1-2)
In formula (1-2), M ² is at least one element selected from the group consisting of Al, Fe, Mg, Zr, Ti, B and Sn, and d is 0.9 ≦ d ≦ 1.2. , E, f, g and h satisfy the conditions of e + f + g + h = 1, 0 ≦ e ≦ 0.7, 0 ≦ f ≦ 0.5, 0 ≦ g ≦ 0.5, and h ≧ 0.
Lithium-nickel-manganese-cobalt composite oxides contain manganese in the range shown in the general formula (1-2) in order to improve structural stability and improve safety at high temperatures in lithium secondary batteries. It is preferable, and in particular, those further containing cobalt in the range represented by the general formula (1-2) in order to enhance the high rate characteristics of the lithium ion secondary battery are more preferable.
_{Specifically, for example, Li [Ni 1/3} Mn _1/3 Co _1/3 ] O ₂ and Li [Ni _0.45 Mn _0.35 Co _0.2 ] having a charge / discharge region of 4.3 V or more. O ₂ , Li [Ni _0.5 Mn _0.3 Co _0.2 ] O ₂ , Li [Ni _0.6 Mn _0.2 Co _0.2 ] O ₂ , Li [Ni _0.49 Mn _0.3 Co _Examples thereof include 0.2 Zr _0.01 ] O ₂ , Li [Ni _0.49 Mn _0.3 Co _0.2 Mg _0.01 ] O _2.
((B) Lithium manganese composite oxide having a spinel structure)
Examples of the lithium manganese composite oxide having a positive electrode active material (B) spinel structure include spinel-type lithium manganese composite oxides represented by the general formula (1-3).
Li _j (Mn _2-k M ³ _k ) O ₄ (1-3)
In formula (1-3), M ³ is at least one metal element selected from the group consisting of Ni, Co, Fe, Mg, Cr, Cu, Al and Ti, and j is 1.05 ≦ j ≦ 1. 15 and k is 0 ≦ k ≦ 0.20.
Specifically, for example, LiMn ₂ O ₄ , LiMn _1.95 Al _0.05 O ₄ , LiMn _1.9 Al _0.1 O ₄ , LiMn _1.9 Ni _0.1 O ₄ , LiMn _1.5 Ni. _Examples include 0.5 O _{4 and the} like.
((C) Lithium-containing olivine phosphate)
Examples of the positive electrode active material (C) lithium-containing olivine-type phosphate include those represented by the general formula (1-4).
LiFe _1-n M ⁴ _n PO ₄ (1-4)
In the formula (1-4), M ⁴ is at least one selected from Co, Ni, Mn, Cu, Zn, Nb, Mg, Al, Ti, W, Zr and Cd, and n is 0 ≦ n ≦. It is 1.
Specifically, for example, LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , LiMnPO _{4 and the} like can be mentioned, and among them, LiFePO ₄ and / or LiMnPO ₄ are preferable.
((D) Lithium excess layered transition metal oxide)
Examples of the lithium excess layered transition metal oxide having a positive electrode active material (D) layered rock salt type structure include those represented by the general formula (1-5).
xLiM ⁵ O ₂ · (1-x) Li ₂ M ⁶ O ₃ (1-5)
Wherein (1-5), x is 0 <a number satisfying x <1, ^{M 5} is at least one or more metal elements mean oxidation number is ^{3 +, M 6,} the average oxide the number is at least one or more metal elements 4 ^+. In formula (1-5), M ⁵ is one or more metal elements preferably selected from trivalent Mn, Ni, Co, Fe, V, and Cr, and is divalent, tetravalent, or the like. The average oxidation number may be trivalent with an amount of metal.
Further, in the formula (1-5), M ⁶ is one or more metal elements preferably selected from Mn, Zr, and Ti. Specifically, 0.5 [LiNi _0.5 Mn _0.5 O ₂ ], 0.5 [Li ₂ MnO ₃ ], 0.5 [LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ] -0.5 [Li ₂ MnO ₃ ], 0.5 [LiNi _0.375 Co _0.25 Mn _0.375 O ₂ ]-0.5 [Li ₂ MnO ₃ ], 0.5 [LiNi _0.375 Co _0.125 Fe _0.125 Mn _0.375 O ₂ ] ・ 0.5 [Li ₂ MnO ₃ ], 0.45 [LiNi _0.375 Co _0.25 Mn _0.375 O ₂ ] ・ 0.10 [Li ₂ TiO ₃ ], 0.45 [Li ₂ MnO ₃ ] and the like can be mentioned.
The positive electrode active material (D) represented by this general formula (1-5) is known to exhibit a high capacity at a high voltage charge of 4.4 V (Li standard) or higher (for example, US Pat. No. 7, Ltd. 7). , 135, 252).
These positive electrode active materials can be prepared according to, for example, the production methods described in JP-A-2008-270201, WO2013 / 118661, JP2013-030284, and the like.
The positive electrode active material may contain at least one selected from the above (A) to (D) as a main component, but other materials include, for example, FeS ₂ , TiS ₂ , and V ₂ O _5. , MoO ₃ , MoS _{2, and} other transition elements chalcogenides, or conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, polymers that generate radicals, carbon materials, and the like.
[Positive current collector]
(B) The positive electrode has a positive electrode current collector. As the positive electrode current collector, for example, aluminum, stainless steel, nickel, titanium, alloys thereof, or the like can be used.
[Positive electrode active material layer]
(A) In the positive electrode, for example, a positive electrode active material layer is formed on at least one surface of a positive electrode current collector. The positive electrode active material layer is composed of, for example, the above-mentioned positive electrode active material, a binder, and, if necessary, a conductive agent.
Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride, styrene butadiene rubber (SBR) resin and the like.
As the conductive agent, for example, a carbon material such as acetylene black, ketjen black, carbon fiber, or graphite (granular graphite or flake graphite) can be used. For the positive electrode, it is preferable to use acetylene black or Ketjen black having low crystallinity.
[(C) Negative electrode]
(C) The negative electrode preferably contains at least one type of negative electrode active material.
[Negative electrode active material]
In the case of a lithium ion secondary battery in which the cation in the non-aqueous electrolyte solution is mainly lithium, (c) the negative electrode active material constituting the negative electrode can be dope / dedope of lithium ions. For example, (E) a carbon material having a d-value of the lattice surface (002 surface) of 0.340 nm or less in X-ray diffraction, and (F) carbon having a d-value of the lattice surface (002 surface) of more than 0.340 nm in X-ray diffraction. With materials, oxides of one or more metals selected from (G) Si, Sn, Al, one or more metals selected from (H) Si, Sn, Al, alloys containing these metals, or these metals or alloys. Examples thereof include an alloy with lithium and one containing at least one selected from (I) lithium titanium oxide. One of these negative electrode active materials can be used alone, and two or more of them can be used in combination.
((E) A carbon material having a d value of 0.340 nm or less on the lattice plane (002 plane) in X-ray diffraction)
Negative electrode activated carbon (E) Examples of carbon materials having a d-value of 0.340 nm or less on the lattice plane (002 plane) in X-ray diffraction include pyrolytic carbons and coke (for example, pitch coke, needle coke, petroleum coke, etc.). , Graphites, calcined organic polymer compound (for example, phenol resin, furan resin, etc. are calcined at an appropriate temperature and carbonized), carbon fiber, activated carbon, etc., and these may be graphitized. The carbon material has a plane spacing (d002) of the (002) plane measured by an X-ray diffraction method of 0.340 nm or less, and among them, ^{graphite having a true density of 1.70 g / cm 3} or more, or graphite thereof. A highly crystalline carbon material having similar properties is preferable.
((F) Carbon material in which the d value of the lattice plane (002 plane) in X-ray diffraction exceeds 0.340 nm)
Amorphous carbon is mentioned as a carbon material in which the d value of the lattice plane (002 plane) in the negative electrode active material (F) X-ray diffraction exceeds 0.340 nm, and this is heat-treated at a high temperature of 2000 ° C. or higher. Is a carbon material whose stacking order hardly changes. Examples thereof include non-graphitized carbon (hard carbon), mesocarbon microbeads (MCMB) calcined at 1500 ° C. or lower, mesopaise bitch carbon fiber (MCF), and the like. Carbotron (registered trademark) P manufactured by Kureha Corporation is a typical example.
(Oxide of one or more metals selected from (G) Si, Sn, Al)
Examples of the oxide of one or more metals selected from the negative electrode active material (G) Si, Sn, and Al include silicon oxide, tin oxide, and the like, which can dope and remove lithium ions. ..
There are _{SiO x and the} like having a structure in which ultrafine particles of Si _{are dispersed in SiO 2.} When this material is used as the negative electrode active material, charging and discharging are smoothly performed because Si that reacts with Li is ultrafine particles, while the SiO _x particles themselves having the above structure have a small surface area, so that the negative electrode active material layer. The paintability of the composition (paste) for forming the negative electrode mixture layer and the adhesiveness of the negative electrode mixture layer to the current collector are also good.
Since SiO _x has a large volume change with charge and discharge, the _{capacity can be increased and good charge / discharge cycle characteristics can be achieved by using SiO x} and the graphite of the negative electrode active material (E) in a specific ratio in combination with the negative electrode active material. Can be compatible with.
((H) One or more metals selected from Si, Sn, Al, alloys containing these metals, or alloys of these metals or alloys with lithium)
Negative electrode active material (H) One or more metals selected from Si, Sn, Al, alloys containing these metals, or alloys of these metals or alloys with lithium include, for example, metals such as silicon, tin, aluminum, and silicon alloys. , Tin alloys, aluminum alloys, etc., and materials in which these metals and alloys are alloyed with lithium during charge and discharge can also be used.
Preferred specific examples of these are metal simple substances (for example, powdery ones) such as silicon (Si) and tin (Sn) described in WO2004 / 100293 and Japanese Patent Application Laid-Open No. 2008-016424, and the metal alloys thereof. , Compounds containing the metal, alloys containing tin (Sn) and cobalt (Co) in the metal, and the like. When the metal is used for an electrode, it is preferable because it can develop a high charge capacity and the volume expansion / contraction due to charging / discharging is relatively small. Further, these metals are known to exhibit a high charging capacity because they are alloyed with Li during charging when they are used as the negative electrode of a lithium ion secondary battery, which is also preferable.
Further, for example, a negative electrode active material formed of silicon pillars having a submicron diameter, a negative electrode active material made of fibers composed of silicon, and the like described in WO2004 / 042551, WO2007 / 083155, etc. may be used. ..
((I) Lithium Titanium Oxide)
Examples of the negative electrode active material (I) lithium titanate oxide include lithium titanate having a spinel structure and lithium titanate having a rams delite structure.
Examples of lithium titanate having a spinel structure include Li _{4 + α} Ti ₅ O ₁₂ (α changes within the range of 0 ≦ α ≦ 3 due to a charge / discharge reaction). Examples of lithium titanate having a rams delite structure include Li _{2 + β} Ti ₃ O ₇ (β changes within the range of 0 ≦ β ≦ 3 due to a charge / discharge reaction). These negative electrode active materials can be prepared according to, for example, the production methods described in JP-A-2007-018883, JP-A-2009-176752, and the like.
For example, the case of sodium ion secondary battery cations in the non-aqueous electrolyte is sodium mainly hard carbon and _{TiO 2, V 2 O 5,} MoO 3 oxide such like are used as the negative electrode active material. For example, in the case of a sodium ion secondary battery in which the cation in the non-aqueous electrolyte solution is mainly sodium, sodium-containing transition metal composite oxides such _{as NaFeO 2} , NaCrO ₂ , NanoNiO ₂ , NamnO ₂ , and NaCoO _{2 are used as positive electrode active materials.} A mixture of multiple transition metals such as Fe, Cr, Ni, Mn, and Co of those sodium-containing transition metal composite oxides, and some of the transition metals of those sodium-containing transition metal composite oxides are other than other transition metals. Substituted with the metal of Na ₂ FeP ₂ O ₇ , NaCo ₃ (PO ₄ ) ₂ P ₂ O _{7 and} other transition metal phosphate compounds, TiS ₂ , FeS _{2 and} other sulfides, or polyacetylene and polypara Conductive polymers such as phenylene, polyaniline, and polypyrrole, activated carbon, radical-generating polymers, carbon materials, and the like are used.
[Negative electrode current collector]
(C) The negative electrode has a negative electrode current collector. As the negative electrode current collector, for example, copper, stainless steel, nickel, titanium, alloys thereof, or the like can be used.
[Negative electrode active material layer]
(C) In the negative electrode, for example, a negative electrode active material layer is formed on at least one surface of a negative electrode current collector. The negative electrode active material layer is composed of, for example, the above-mentioned negative electrode active material, a binder, and, if necessary, a conductive agent.
Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride, styrene butadiene rubber (SBR) resin and the like.
As the conductive agent, for example, a carbon material such as acetylene black, ketjen black, carbon fiber, or graphite (granular graphite or flake graphite) can be used.
[Manufacturing method of electrodes ((a) positive electrode and (c) negative electrode)]
The electrode is obtained, for example, by dispersing and kneading an active material, a binder, and, if necessary, a conductive agent in a solvent such as N-methyl-2-pyrrolidone (NMP) or water in a predetermined blending amount. It can be obtained by applying the paste to a current collector and drying it to form an active material layer. It is preferable that the obtained electrode is compressed by a method such as a roll press to adjust the electrode to an appropriate density.
[(D) Separator]
The above-mentioned non-aqueous electrolyte battery includes (d) a separator. As the separator for preventing contact between (a) the positive electrode and (c) the negative electrode, polyolefins such as polypropylene and polyethylene, and non-woven fabrics and porous sheets made of cellulose, paper, glass fiber and the like are used. These films are preferably microporous so that the electrolytic solution can penetrate and ions can easily permeate.
Examples of the polyolefin separator include a film such as a microporous polymer film such as a porous polyolefin film that electrically insulates the positive electrode and the negative electrode and allows lithium ions to permeate. As a specific example of the porous polyolefin film, for example, the porous polyethylene film may be used alone, or the porous polyethylene film and the porous polypropylene film may be laminated and used as a multi-layer film. Further, a composite film of a porous polyethylene film and a polypropylene film and the like can be mentioned.
[Exterior body]
In constructing the non-aqueous electrolyte battery, as the exterior body of the non-aqueous electrolyte battery, for example, a metal can such as a coin type, a cylindrical type, or a square type, or a laminated exterior body can be used. Examples of the metal can material include a nickel-plated iron steel plate, a stainless steel plate, a nickel-plated stainless steel plate, aluminum or an alloy thereof, nickel, titanium and the like.
As the laminated exterior body, for example, an aluminum laminated film, a SUS laminated film, a silica-coated polypropylene, a laminated film such as polyethylene, or the like can be used.
The configuration of the non-aqueous electrolyte battery according to the present embodiment is not particularly limited, but for example, an electrode element in which a positive electrode and a negative electrode are arranged to face each other and a non-aqueous electrolyte are encapsulated in an exterior body. Can be configured as The shape of the non-aqueous electrolyte battery is not particularly limited, but an electrochemical device having a shape such as a coin shape, a cylinder shape, a square shape, or an aluminum laminated sheet type can be assembled from each of the above elements.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these descriptions.

(Preparation of No. 1 additive for non-aqueous electrolyte solution)
Vinylene carbonate (hereinafter referred to as "VC") 10 g of N-methylpyrrolidone (hereinafter referred to as "NMP") 40 mL solution in 2,2'-azobis (isobutyric acid) dimethyl (V601: manufactured by Wako Pure Chemical Industries, Ltd.) 4 After adding 5.5 g, degassing under vacuum and introducing nitrogen three times to create a nitrogen atmosphere, the mixture was heated at 80 ° C. for 6 hours. The obtained reaction solution was poured into a large amount of methanol, and the polymer was reprecipitated using the methanol as a poor solvent. The precipitate was separated by filtration and the polymer was recovered. The obtained polymer was dried under reduced pressure at 60 ° C. for 4 hours to remove the residual solvent, and the non-aqueous electrolyte solution additive No. 1 was obtained in 3.8 g and a yield of 38%.
Additive No. for non-aqueous electrolyte solution 1 ¹ H-NMR measurement of 1 was carried out, and it was confirmed that all Rs of the above general formula [1] were H and that the compound was composed of an oligomer. In addition, the additive No. for non-aqueous electrolyte solution No. The GPC measurement of 1 was performed, and it was confirmed that the polystyrene-equivalent number average molecular weight was 750. The results are shown in Table 1.

(Preparation of Additive No. 2 for non-aqueous electrolyte solution)
Add 4.0 g of 2,2'-azobis (isobutyric acid) dimethyl (V601: manufactured by Wako Pure Chemical Industries, Ltd.) to a solution of 10 g of VC in 40 mL of NMP, perform degassing under vacuum and introduce nitrogen three times, and nitrogen. After setting the atmosphere, the mixture was heated at 80 ° C. for 6 hours. The obtained reaction solution was poured into a large amount of methanol, and the polymer was reprecipitated using the methanol as a poor solvent. The precipitate was separated by filtration and the polymer was recovered. The obtained polymer was dried under reduced pressure at 60 ° C. for 4 hours to remove the residual solvent, and the non-aqueous electrolyte solution additive No. 2 was obtained in 4.4 g and a yield of 44%.
Additive No. for non-aqueous electrolyte solution ¹ H-NMR measurement of 2 was carried out, and it was confirmed that all R of the above general formula [1] was H and that the compound was composed of an oligomer. In addition, the additive No. for non-aqueous electrolyte solution No. GPC measurement of 2 was performed, and it was confirmed that the polystyrene-equivalent number average molecular weight was 1000. The results are shown in Table 1.

(Preparation of Additive No. 3 for non-aqueous electrolyte solution)
Add 4.0 g of 2,2'-azobis (isobutyric acid) dimethyl (V601: manufactured by Wako Pure Chemical Industries, Ltd.) to a solution of 10 g of VC in 20 mL of NMP, degas under vacuum, and introduce nitrogen three times. After setting the atmosphere, the mixture was heated at 80 ° C. for 6 hours. The obtained reaction solution was poured into a large amount of methanol, and the polymer was reprecipitated using the methanol as a poor solvent. The precipitate was separated by filtration and the polymer was recovered. The obtained polymer was dried under reduced pressure at 60 ° C. for 4 hours to remove the residual solvent, and the non-aqueous electrolyte solution additive No. 3 was obtained in 7.8 g and a yield of 78%.
Additive No. for non-aqueous electrolyte solution ^{1 1} H-NMR measurement of 3 was carried out, and it was confirmed that all Rs of the above general formula [1] were H and that the compound was composed of an oligomer. In addition, the additive No. for non-aqueous electrolyte solution No. GPC measurement of 3 was performed, and it was confirmed that the polystyrene-equivalent number average molecular weight was 2000. The results are shown in Table 1.

(Preparation of Additive No. 4 for non-aqueous electrolyte solution)
Add 2.3 g of 2,2'-azobis (isobutyric acid) dimethyl (V601: manufactured by Wako Pure Chemical Industries, Ltd.) to a solution of 10 g of VC in 20 mL of NMP, degas under vacuum, and introduce nitrogen three times. After setting the atmosphere, the mixture was heated at 80 ° C. for 6 hours. The obtained reaction solution was poured into a large amount of methanol, and the polymer was reprecipitated using the methanol as a poor solvent. The precipitate was separated by filtration and the polymer was recovered. The obtained polymer was dried under reduced pressure at 60 ° C. for 4 hours to remove the residual solvent, and the non-aqueous electrolyte solution additive No. 4 was obtained in 7.5 g and a yield of 75%.
Additive No. for non-aqueous electrolyte solution ¹ H-NMR measurement of No. 4 was carried out, and it was confirmed that all Rs of the above general formula [1] were H and that the compound was composed of an oligomer. In addition, the additive No. for non-aqueous electrolyte solution No. GPC measurement of 4 was performed, and it was confirmed that the polystyrene-equivalent number average molecular weight was 2500. The results are shown in Table 1.

(Preparation of Additive No. 5 for non-aqueous electrolyte solution)
Add 1.5 g of 2,2'-azobis (isobutyric acid) dimethyl (V601: manufactured by Wako Pure Chemical Industries, Ltd.) to a solution of 10 g of VC in 20 mL of NMP, degas under vacuum, and introduce nitrogen three times. After setting the atmosphere, the mixture was heated at 80 ° C. for 6 hours. The obtained reaction solution was poured into a large amount of methanol, and the polymer was reprecipitated using the methanol as a poor solvent. The precipitate was separated by filtration and the polymer was recovered. The obtained polymer was dried under reduced pressure at 60 ° C. for 4 hours to remove the residual solvent, and the non-aqueous electrolyte solution additive No. 5 was obtained in 8.3 g and a yield of 83%.
Additive No. for non-aqueous electrolyte solution ¹ H-NMR measurement of No. 5 was carried out, and it was confirmed that all Rs of the above general formula [1] were H and that the compound was composed of an oligomer. In addition, the additive No. for non-aqueous electrolyte solution No. GPC measurement of 5 was performed, and it was confirmed that the polystyrene-equivalent number average molecular weight was 4500. The results are shown in Table 1.

(Preparation of Additive No. 6 for Non-Aqueous Electrolyte)
Add 0.5 g of 2,2'-azobis (isobutyric acid) dimethyl (V601: manufactured by Wako Pure Chemical Industries, Ltd.) to a solution of 10 g of VC in 20 mL of NMP, degas under vacuum, and introduce nitrogen three times. After setting the atmosphere, the mixture was heated at 80 ° C. for 6 hours. The obtained reaction solution was poured into a large amount of methanol, and the polymer was reprecipitated using the methanol as a poor solvent. The precipitate was separated by filtration and the polymer was recovered. The obtained polymer was dried under reduced pressure at 60 ° C. for 4 hours to remove the residual solvent, and the non-aqueous electrolyte solution additive No. 6 was obtained in 8.1 g and a yield of 81%.
Additive No. for non-aqueous electrolyte solution ¹ H-NMR measurement of No. 6 was carried out, and it was confirmed that all Rs of the above general formula [1] were H and that the compound was composed of an oligomer. In addition, the additive No. for non-aqueous electrolyte solution No. GPC measurement of 6 was performed, and it was confirmed that the polystyrene-equivalent number average molecular weight was 6500. The results are shown in Table 1.

(Preparation of non-aqueous electrolyte solution)
The non-aqueous organic solvent of (III) was prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3: 7. _{Lithium hexafluorophosphate (LiPF 6} ) as (IV) was dissolved in this solvent at a ratio of 1 mol / L, and the solution was added to the solution.
As (I), lithium difluorobis (oxalate) phosphate was added so as to have the concentration shown in Table 2.
By adding the additives for non-aqueous electrolyte solutions of the types shown in Table 2 as (II) to the concentrations shown in Table 2,
Electrolyte No. 1-1-1 to 1-14 were obtained.
In addition, electrolytic solution No. For 1-6 and 1-7, VC corresponding to the monomer of (II) was added as other components so as to be 0.015% by mass and 0.25% by mass, respectively, with respect to the total amount of the electrolytic solution. I got it.
In addition, the electrolytic solution No. In 1-3, as other components, bis (fluorosulfonyl) imidelithium (hereinafter sometimes referred to as "LiFSI") and 1,3-propanesulton (hereinafter "PS"), which are "second additives". , 1,3-Propensulton (hereinafter sometimes referred to as "PRS"), methylenemethane disulfonate (hereinafter sometimes referred to as "MMDS"), 1,5,2 , 4-Dioxadithian-6-trifluoroethyl-2,2,4,4-tetraoxide (hereinafter sometimes referred to as "TFP-MDS"), vinyl ethylene carbonate (hereinafter sometimes referred to as "VEC"). ), Bis (difluorophosphoryl) imidelithium (hereinafter sometimes referred to as "LiFPI"), ethoxy (pentafluoro) cyclotriphosphazene (hereinafter sometimes referred to as HISHICOLEINE (manufactured by Nippon Kagaku Kogyo Co., Ltd.)), Tetrafluorophosphonyl picolinic acid (hereinafter sometimes referred to as "TFPPA"), difluorophosphoryl (fluorophosphoryl) imide dilithium (hereinafter sometimes referred to as "LiDFP-FPI"), difluorophosphoryl (trifluoromethanesulfonyl) Imidolithium (hereinafter sometimes referred to as "LiDFP-TFMSI"), difluorophosphoryl (vinylsulfonyl) imidolithium (hereinafter sometimes referred to as "LiDFP-VSI"), fluorotrivinylsilane (hereinafter referred to as "FTVSi") (May be referred to as “TVSi”), tetravinylsilane (hereinafter sometimes referred to as “TVSi”), and difluorophosphoryl (fluorosulfonyl) imidelithium (hereinafter sometimes referred to as “LiDFP-FSI”), respectively, in Table 4. By adding to the indicated concentration,
Electrolyte No. 1-15-1-29 were obtained.
Further, as shown in Table 6, instead of lithium difluorobis (oxalate) phosphate, lithium difluorophosphate (hereinafter, also referred to as “LiPO ₂ F ₂ ” in the table) was used, and the concentration of (I) was used. , (II) as shown in Table 6, and the electrolytic solution No. 2-1 to 2-14 were obtained.
In addition, electrolytic solution No. In 2-6 and 2-7, VC corresponding to the monomer of (II) was added as other components so as to be 0.015% by mass and 0.25% by mass, respectively, with respect to the total amount of the electrolytic solution. I got it.
In addition, the electrolytic solution No. In addition to 2-3, as other components, "second additive", LiFSI, PS, PRS, MMDS, TFP-MDS, VEC, LiFPI, HISHOCOLINE, TFPPA, LiDFP-FPI, LiDFP-TFMSI, LiDFP By adding −VSI, FTVSi, TVSi, and LiDFP-FSI to the concentrations shown in Table 8, respectively.
Electrolyte No. 2-15 to 2-29 were obtained.
Also, instead of lithium difluorobis (oxalate) phosphate, lithium difluorobis (oxalate) phosphate and LiPO ₂ F ₂ should be used in the ratio shown in Table 10, and the type and content of (II), ( Except for the fact that the type of III) was changed as shown in Table 10, the electrolyte No. In the same manner as in 1-14, the electrolytic solution No. 3-1 to 3-10 were obtained. "EC / EMC / DMC3 / 4/3" is a non-aqueous organic solvent in which EC, EMC and dimethyl carbonate (DMC) are mixed at a volume ratio of 3: 4: 3, and "EC / EMC / FEC3 / 6" is used. "1/1" is a non-aqueous organic solvent in which EC, EMC and fluoroethylene carbonate (FEC) are mixed at a volume ratio of 3: 6: 1, and "EC / EMC / PC3 / 5/2" is EC and EMC. It is a non-aqueous organic solvent in which propylene carbonate (PC) is mixed in a volume ratio of 3: 5: 2.
In addition, the electrolytic solution No. In addition to 3-5, as other components, "second additive", LiFSI, PS, PRS, MMDS, TFP-MDS, VEC, LiFPI, HISHOCOLINE, TFPPA, LiDFP-FPI, LiDFP-TFMSI, LiDFP By adding −VSI, FTVSi, TVSi, and LiDFP-FSI to the concentrations shown in Table 12, respectively,
Electrolyte No. 3-11 to 3-25 were obtained.
Further, as shown in Table 14, instead of lithium difluorobis (oxalate) phosphate, lithium difluoro (oxalate) borate was used, and the concentration of (I) and the type and concentration of (II) were shown in Table 14. Then, the electrolytic solution No. 4-1 to 4-14 were obtained.
In addition, electrolytic solution No. In 4-6 and 4-7, VC corresponding to the monomer of (II) was added as other components so as to be 0.015% by mass and 0.25% by mass, respectively, with respect to the total amount of the electrolytic solution. I got it.
In addition, the electrolytic solution No. In addition to 4-3, as other components, "second additive" LiFSI, PS, PRS, MMDS, TFP-MDS, VEC, LiFPI, HISHOCOLINE, TFPPA, LiDFP-FPI, LiDFP-TFMSI, LiDFP- By adding VSI, FTVSi, TVSi, and LiDFP-FSI to the concentrations shown in Table 16, respectively,
Electrolyte No. 4-15 to 4-29 were obtained.
Further, as shown in Table 18, instead of lithium difluorobis (oxalate) phosphate, lithium tetrafluoro (oxalate) phosphate is used, and the concentration of (I) and the type and concentration of (II) are shown in Table 18. In this way, the electrolyte No. 5-1 to 5-14 were obtained.
In addition, electrolytic solution No. In 5-6 and 5-7, VC corresponding to the monomer of (II) was added as other components so as to be 0.015% by mass and 0.25% by mass, respectively, with respect to the total amount of the electrolytic solution. I got it.
In addition, the electrolytic solution No. In addition to 5-3, as other components, "second additive", LiFSI, PS, PRS, MMDS, TFP-MDS, VEC, LiFPI, HISHOCOLINE, TFPPA, LiDFP-FPI, LiDFP-TFMSI, LiDFP By adding −VSI, FTVSi, TVSi, and LiDFP-FSI to the concentrations shown in Table 20, respectively,
Electrolyte No. 5-15-5-29 were obtained.

In addition, the comparative electrolyte No. 1-1 and 1-15-1-29 were obtained by adding VC corresponding to the monomer of (II) without adding (II) as shown in Tables 2 and 4.
In addition, the comparative electrolyte No. As shown in Table 2, 1-2 is the additive No. 1 for non-aqueous electrolyte solution as (II). It was obtained by adding 6.
In addition, the comparative electrolyte No. As shown in Table 6, 2-1 is the comparative electrolyte No. _{In 1-1, LiPO 2} F ₂ was used instead of lithium difluorobis (oxalate) phosphate so that the concentration was 1.0% by mass.
In addition, the comparative electrolyte No. As shown in Table 8, 2-15 to 2-29 are each electrolytic solution No. 2 except that VC corresponding to the monomer of (II) was added without adding (II). It was obtained in the same manner as 2--15 to 2-29.
In addition, the comparative electrolyte No. As shown in Table 6, 2-2 shows the additive No. 2 for non-aqueous electrolyte solution as (II). It was obtained by adding 6.
In addition, instead of lithium difluorobis (oxalate) phosphate, lithium difluorobis (oxalate) phosphate and LiPO ₂ F ₂ should be used so as to have the ratio shown in Table 10, and the types of (III) and the like are shown in Table 10. Comparative electrolyte No. except that it was changed as shown. Comparative electrolyte No. 1 in the same manner as 1-1. 3-1 to 3-6 were obtained.
In addition, the comparative electrolyte No. As shown in Table 12, 3-11 to 3-25 each had an electrolytic solution No. 1 except that VC corresponding to the monomer of (II) was added without adding (II). It was obtained in the same manner as 3-11 to 3-25.
In addition, the comparative electrolyte No. As shown in Table 14, 4-1 contains Comparative Electrolyte No. It was obtained by using lithium difluoro (oxalate) oxalate instead of LiPO ₂ F _{2 in 2-1.}
In addition, the comparative electrolyte No. As shown in Table 14, 4-2 is designated as (II) in the non-aqueous electrolyte solution additive No. It was obtained by adding 6.
In addition, the comparative electrolyte No. As shown in Table 16, 4-15 to 4-29 each of the electrolytic solution Nos. 4-15 to 4-29, except that VC corresponding to the monomer of (II) was added without adding (II). It was obtained in the same manner as 4-15 to 4-29.
In addition, the comparative electrolyte No. As shown in Table 18, 5-1 shows the comparative electrolyte No. It was obtained by using lithium tetrafluoro (oxalate) phosphate instead of LiPO ₂ F _{2 in 2-1.}
In addition, the comparative electrolyte No. As shown in Table 18, 5-2 is the additive No. 2 for non-aqueous electrolyte solution as (II). It was obtained by adding 6.
In addition, the comparative electrolyte No. As shown in Table 20, 5-15 to 5-29 are the electrolytic solution Nos., except that VC corresponding to the monomer of (II) was added without adding (II). It was obtained in the same manner as 5-15 to 5-29.

Using this electrolytic solution, a cell was prepared using LiNi _1/3 Co _1/3 Mn _1/3 O ₂ as a positive electrode material and graphite as a negative electrode material, and the initial electric capacity, cycle characteristics, and rate characteristics of the battery were actually evaluated. did. The test cell was prepared as follows.

LiNi _1/3 Co _1/3 Mn _1/3 O ₂ powder 90% by mass mixed with 5% by mass polyvinylidene fluoride (hereinafter referred to as "PVDF") as a binder and 5% by mass of acetylene black as a conductive material. Further, N-methylpyrrolidone was added to form a paste. This paste was applied onto an aluminum foil and dried to obtain a positive electrode body for testing. Further, PVDF of 10% by mass as a binder was mixed with 90% by mass of graphite powder, and N-methylpyrrolidone was further added to form a slurry. This slurry was applied onto a copper foil and dried at 150 ° C. for 12 hours to prepare a test negative electrode body. Then, the electrolytic solution was impregnated into the polyethylene separator to assemble a 50 mAh cell having an aluminum laminated exterior.

[Initial electric capacity]
Using the prepared cell, after charging at a current density of 0.35 mA / cm ² up to 4.2 V, was discharged at a current density of 0.35 mA / cm ² up to 3.0 V, electricity first discharge capacity at this time early The capacity was set. The measurement was performed at an environmental temperature of 25 ° C.

[High temperature cycle characteristics]
Using the above cell, a charge / discharge test was carried out at an environmental temperature of 60 ° C. to evaluate the cycle characteristics. Both charging and discharging were performed at a current rate of 3C, charging was maintained at 4.2V for 1 hour after reaching 4.2V, discharging was performed up to 3.0V, and the charging / discharging cycle was repeated. Then, the degree of cell deterioration was evaluated by the discharge capacity retention rate after 500 cycles (cycle characteristic evaluation). The discharge capacity retention rate was calculated by the following formula.
<Discharge capacity retention rate after 500 cycles>
Discharge capacity retention rate (%) = (Discharge capacity after 500 cycles / Initial discharge capacity) x 100
The results are shown in Tables 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21.
The values of the cycle characteristics in Tables 3, 7, 15 and 19 are relative values with the value of the cycle characteristics of Comparative Examples 1-1, 2-1 and 4-1, 5-1 as 100, respectively.
Further, in the cycle characteristics of Table 11, the values of Examples 3-1 and 3-7 to 3-10 are relative values with the value of Comparative Example 3-1 as 100, and the values of Example 3-2 are compared. The value of Example 3-2 is a relative value of 100, the value of Example 3-3 is a relative value of Comparative Example 3-3 as 100, and the value of Example 3-4 is Comparative Example 3. The value of -4 is a relative value of 100, the value of Example 3-5 is a relative value of Comparative Example 3-5 as 100, and the value of Example 3-6 is Comparative Example 3-6. It is a relative value where the value of is 100.
The cycle characteristic values in Tables 5, 9, 13, 17, and 21 are relative values with the cycle characteristic values of the corresponding comparative examples as 100, respectively.

[Rate characteristics]
Using the above cell, a charge / discharge test was carried out at an environmental temperature of 25 ° C. to evaluate high rate characteristics. Charging is always performed at a current rate of 0.2C, and after reaching 4.2V, 4.2V is maintained for 1 hour, and discharge is up to 3.0V. By measurement, the discharge capacity ratio at the time of 0.2C discharge and 5C discharge was calculated by the following formula.
<Discharge capacity ratio of high rate characteristics>
High-rate discharge capacity ratio (%) = (discharge capacity at 5C discharge / discharge capacity at 0.2C discharge) x 100
The results are shown in Tables 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21.
The rate characteristic values in Tables 3, 7, 15 and 19 are relative values with the rate characteristic values in Comparative Examples 1-1, 2-1 and 4-1, 5-1 as 100, respectively.
Further, in the rate characteristics of Table 11, the values of Examples 3-1 and 3-7 to 3-10 are relative values with the value of Comparative Example 3-1 as 100, and the values of Example 3-2 are compared. The value of Example 3-2 is a relative value of 100, the value of Example 3-3 is a relative value of Comparative Example 3-3 as 100, and the value of Example 3-4 is Comparative Example 3. The value of -4 is a relative value of 100, the value of Example 3-5 is a relative value of Comparative Example 3-5 as 100, and the value of Example 3-6 is Comparative Example 3-6. It is a relative value where the value of is 100.
The rate characteristic values in Tables 5, 9, 13, 17, and 21 are relative values with the rate characteristic values of the corresponding comparative examples as 100, respectively.

As can be seen from Examples 1-1-1-5
When the polystyrene-equivalent number average molecular weight of the additive for a non-aqueous electrolyte solution of the present invention is 170 to 5000, the cycle characteristics and the rate characteristics can be exhibited in a well-balanced manner when used in a non-aqueous electrolyte solution secondary battery. it can.
On the other hand, a comparison using an electrolytic solution in which VC (a compound corresponding to the monomer of the general formula [1]) corresponding to the monomer was added instead of adding the additive for the non-aqueous electrolytic solution of the present invention. In Example 1-1, it was confirmed that the cycle characteristics and the rate characteristics tended to be inferior to those in the above-mentioned Examples.
Further, it was also confirmed that in Comparative Example 1-2 to which the compound having the polystyrene-equivalent number average molecular weight of more than 5000 was added, the cycle characteristics and the rate characteristics tended to be inferior to those of the above Examples.

Further, from Examples 1-3, 1-8 to 1-13, the content of (II) is 0.03 to 100% by mass based on the total amount of (I), (II), (III), and (IV). When it is 14.0% by mass, when it is used in a non-aqueous electrolyte secondary battery, it is easy to exhibit cycle characteristics and rate characteristics in a well-balanced manner, and the content of (II) is 0.07 to 12.0% by mass. It turns out that it is more preferable.

Further, from Examples 1-6 and 1-7, it was confirmed that when the value of (M) / (P) (mass ratio) is 0 to 0.05, the rate characteristics tend to be better. It was.

Further, as can be seen from Examples 2-1 to 2-14, even when difluorophosphate is used as (I), the cycle characteristics and rate characteristics can be improved by using the additive for non-aqueous electrolyte solution of the present invention. It can be exhibited in a well-balanced manner.

Further, as can be seen from Examples 3-1 to 3-10, even when the oxalate salt and the difluorophosphate are used as (I), the cycle characteristics and the cycle characteristics can be obtained by using the additive for the non-aqueous electrolyte solution of the present invention. The rate characteristics can be exhibited in a well-balanced manner.

Further, as can be seen from Examples 4-1 to 4-14, even when lithium difluoro (oxalate) borate is used as (I), the cycle characteristics and cycle characteristics can be obtained by using the additive for non-aqueous electrolyte solution of the present invention. The rate characteristics can be exhibited in a well-balanced manner.

Further, as can be seen from Examples 5-1 to 5-14, even when lithium tetrafluoro (oxalate) phosphate is used as (I), the cycle characteristics can be obtained by using the additive for non-aqueous electrolyte solution of the present invention. And the rate characteristics can be exhibited in a well-balanced manner.

In addition, Examples 1-15-1-29, Examples 2-15-2-29, Examples 3-1-1-3-25, Examples 4-15-4-29, Examples 5-15-5-5 As can be seen from 29, even when an electrolytic solution containing a "second additive" is used as another component, the cycle characteristics and rate characteristics are well-balanced by using the additive for non-aqueous electrolyte solution of the present invention. Can be demonstrated.

Claims (16)

It is a compound having a repeating unit represented by the following general formula [1].
The polystyrene-equivalent number average molecular weight is 170-5000.
An additive for a non-aqueous electrolyte solution for inclusion in a non-aqueous electrolyte solution containing an oxalate salt and / or difluorophosphate.

[In the formula, the inside of the parentheses means that each is a repeating unit. R represents a hydrogen atom, a halogen or a lower alkyl group. R may be all the same, may be different, or may be connected to each other to have an annular structure. ] The additive for a non-aqueous electrolyte solution according to claim 1, wherein the number average molecular weight is 340 to 4000. The additive for a non-aqueous electrolyte solution according to claim 1 or 2, wherein the number average molecular weight is 800 to 3000. The additive for a non-aqueous electrolyte solution according to any one of claims 1 to 3, wherein all R is a hydrogen atom. (I) Oxalato salt and / or difluorophosphate,
(II) An additive for a non-aqueous electrolyte solution, which is a compound having a repeating unit represented by the following general formula [1] and having a polystyrene-equivalent number average molecular weight of 170 to 5000.
(III) Non-aqueous organic solvent and
(IV) A non-aqueous electrolyte solution containing a solute.

[In the formula, the inside of the parentheses means that each is a repeating unit. R represents a hydrogen atom, a halogen or a lower alkyl group. R may be all the same, may be different, or may be connected to each other to have an annular structure. ] The non-aqueous electrolyte solution according to claim 5, wherein the number average molecular weight is 340 to 4000. The non-aqueous electrolyte solution according to claim 5 or 6, wherein the number average molecular weight is 800 to 3000. The non-aqueous electrolyte solution according to any one of claims 5 to 7, wherein all R are hydrogen atoms. Any of claims 5 to 8, wherein the content of (II) is 0.03 to 14.0% by mass with respect to 100% by mass of the total amount of (I), (II), (III), and (IV). The non-aqueous electrolyte solution described. Existing in the electrolytic solution,
The total amount of monomers corresponding to the repeating unit represented by the general formula [1] (hereinafter referred to as (M)) and
The total amount of the non-aqueous electrolyte solution additive (monomer equivalent, hereinafter referred to as (P)) is
(M) / (P) = 0 to 0.05 (mass ratio)
The non-aqueous electrolyte solution according to any one of claims 5 to 9. The oxalate salt comprises bis (oxalate) oxalate, difluoro (oxalate) oxalate, tris (oxalate) phosphate, difluorobis (oxalate) phosphate, and tetrafluoro (oxalate) phosphate. The non-aqueous electrolyte solution according to any one of claims 5 to 10, which is at least one selected from the group. The solutes are lithium hexafluorophosphate, lithium tetrafluoroborate, bis (trifluoromethanesulfonyl) imide lithium, bis (pentafluoroethanesulfonyl) imide lithium, bis (fluorosulfonyl) imide lithium, and bis (difluorophosphonyl). The non-aqueous electrolyte solution according to any one of claims 5 to 11, which is at least one selected from the group consisting of imidelithium. The non-aqueous electrolyte solution according to any one of claims 5 to 12, wherein (I) contains at least lithium difluorobis (oxalate) phosphate and lithium difluorophosphate. The (III) non-aqueous organic solvent is at least one selected from the group consisting of cyclic carbonates, chain carbonates, cyclic esters, chain esters, cyclic ethers, chain ethers, sulfone compounds, sulfoxide compounds, and ionic liquids. The non-aqueous electrolyte solution according to any one of claims 5 to 13.
Ionic complex with cyclic structure, salt with imide anion, Si-containing compound, sulfuric acid ester compound, phosphoric acid ester compound, cyclic carbonate compound, isocyanate compound, cyclic acetal compound, cyclic acid anhydride, cyclic phosphazene compound, aromatic compound At least one compound selected from the group consisting of
The non-aqueous electrolyte solution according to any one of claims 5 to 14, further contained. A non-aqueous electrolyte secondary battery comprising at least a positive electrode, a negative electrode, and the non-aqueous electrolyte solution according to any one of claims 5 to 15.