JP7246981B2 - Non-aqueous electrolyte secondary battery - Google Patents

Description

The present invention relates to a non-aqueous electrolyte secondary battery.

Lithium non-aqueous electrolyte secondary batteries that use a lithium-containing transition metal oxide for the positive electrode and a non-aqueous solvent for the electrolyte can achieve high energy density. It is used in a wide range of applications, including large power supplies for railroads, railroads, and load leveling. However, in recent years, the demand for higher performance of non-aqueous electrolyte secondary batteries has been increasing more and more, and improvements in various characteristics have been strongly demanded.

For example, in Patent Document 1, a non-aqueous electrolyte secondary battery using an electrolyte containing a fluorine-containing solvent and a silyl ester compound is used to improve low-temperature characteristics, cycle characteristics, and rate characteristics, and to improve safety. It is described that it becomes a non-aqueous electrolyte secondary battery with improved.
In Patent Document 2, when a non-aqueous electrolyte secondary battery is used as a power source for a hybrid vehicle or an electric vehicle, output characteristics and cycle characteristics are extremely important. It is described that by reducing the disturbance, the resistance inside the crystal can be reduced, and a positive electrode active material for non-aqueous electrolyte secondary batteries with good cycle characteristics and long life can be stably provided.

JP 2009-163939 A Japanese Patent Application Laid-Open No. 2007-242288

However, in response to the recent demand for improving the characteristics of non-aqueous electrolyte secondary batteries, the above-described conventional technologies have not yet achieved high levels of various performances of non-aqueous electrolyte secondary batteries. For example, in the non-aqueous electrolyte secondary battery of Patent Document 1, further improvement in battery capacity is required, and in the non-aqueous electrolyte secondary battery of Patent Document 2, the capacity and capacity retention rate after high temperature storage are low, and the high temperature Since a large amount of gas is generated after storage, there has been a demand for improvement in high-temperature life. In particular, large-sized batteries for automobiles are subjected to high temperatures due to heat from motors, solar heat, and the like, depending on the environment in which they are used. Therefore, there has been a demand for a non-aqueous electrolyte secondary battery with improved high-temperature characteristics, such as a high capacity retention rate after high-temperature storage, a small amount of gas generated after high-temperature storage, and high safety.

The present invention provides a non-aqueous electrolyte secondary battery having high capacity, capacity recovery rate, and capacity retention rate after high temperature storage, low gas generation after high temperature storage, and high safety. The task is to provide

As a result of intensive studies to solve the above problems, the present inventors have found that by using a specific positive electrode and a non-aqueous electrolyte secondary battery using a non-aqueous electrolyte containing a specific compound, high-temperature storage can be achieved. The inventors have found that it is possible to obtain a non-aqueous electrolyte secondary battery that has high subsequent capacity and capacity retention rate, generates little gas after high-temperature storage, and is highly safe, thereby arriving at the present invention.
That is, the gist of the present invention is as follows.

[1] A non-aqueous electrolyte secondary battery comprising a positive electrode having a positive electrode active material capable of absorbing and releasing metal ions, a negative electrode having a negative electrode active material capable of absorbing and releasing metal ions, and a non-aqueous electrolyte. wherein the positive electrode active material contains a lithium transition metal compound represented by the following compositional formula (I), and the non-aqueous electrolytic solution contains a compound represented by the following formula (II): Liquid secondary battery.
Li _1+x M ³ O ₂ (I)
(In the above composition formula (I), x is −0.1 or more and 0.5 or less, M ³ is a plurality of elements containing at least Ni and Co, and the Ni/M ³ molar ratio is 0.55 or more. 1.0 or less.)

(In the formula (II), X represents a boron atom, a phosphorus atom or a sulfur atom, a and b represent integers of 0 to 2, R ¹ is an alkyl group having 1 to 10 carbon atoms, an alkenyl group or an alkynyl group, or represents an aryl group or alkoxy group having 6 to 18 carbon atoms, ^hydrogen atoms bonded to carbon atoms may ^be substituted with halogen atoms, and may have an ether bond.
each independently represents an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms or an aryl group having 6 to 18 carbon atoms; c represents an integer of 1 to 3; )

[2] The content of the compound represented by the formula (II) is 0.001% by mass or more and 10% by mass or less with respect to 100% by mass of the non-aqueous electrolyte Aqueous electrolyte secondary battery.
[3] The non-aqueous electrolyte secondary battery according to [1] or [2], wherein the non-aqueous electrolyte contains monofluorophosphate and/or difluorophosphate.
[4] The total content of monofluorophosphate and difluorophosphate is 0.001% by mass or more and 10% by mass or less with respect to 100% by mass of the non-aqueous electrolyte, [1] to [3 ] The non-aqueous electrolyte secondary battery according to any one of the above items.

[5] The non-aqueous electrolytic solution is selected from the group consisting of a chain sulfonate, a cyclic sulfonate, a chain sulfate, a cyclic sulfate, a chain sulfite, a cyclic sulfite, and an organic compound having a cyano group. [1] containing at least one compound
The non-aqueous electrolyte secondary battery according to any one of [4].
[6] The nonaqueous electrolyte secondary battery according to any one of [1] to [5], wherein the positive electrode has a plate density of 3.0 g/cm ³ or more.
[7] [1] to [6] wherein the amount of sulfate contained in the positive electrode active material is 15 μmol/g or more
] The non-aqueous electrolyte secondary battery according to any one of the above.

According to the present invention, it is possible to obtain a non-aqueous electrolyte secondary battery having a high capacity, a high capacity retention rate after high-temperature storage, a small amount of gas generation, and excellent safety.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated in detail. However, the description given below is an example (representative example) of the embodiment of the present invention, and the present invention is not limited to these contents as long as the gist of the claims is not exceeded.
An embodiment of the present invention relates to a non-aqueous electrolyte secondary battery, a positive electrode having a positive electrode active material capable of absorbing and releasing metal ions, a negative electrode having a negative electrode active material capable of absorbing and releasing metal ions, and a non-aqueous electrolyte secondary battery. and an electrolytic solution. Each configuration will be described below.

[1. Non-aqueous electrolyte]
[1-1. Compound Represented by Formula (II)]
The non-aqueous electrolyte used in the non-aqueous electrolyte secondary battery of the present invention contains an electrolyte and a non-aqueous solvent that dissolves the same, and is represented by the following formula (II). The main feature is that it contains a compound that

In formula (II), X represents a boron atom, a phosphorus atom or a sulfur atom, a and b represent integers of 0 to 2, R ¹ is an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms or carbon It represents an aryl group or alkoxy group of number 6 to 18, in which hydrogen atoms bonded to carbon atoms may be substituted with halogen atoms or may have an ether bond. ^R2 - ^R4
each independently represents an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms or an aryl group having 6 to 18 carbon atoms; c represents an integer of 1 to 3;

In formula (II), X is preferably a sulfur atom, and the number of carbon atoms in R ¹ is preferably 6 or less, more preferably 3 or less, and most preferably 1. R ¹ is preferably an alkyl group, an alkenyl group or an alkynyl group, more preferably an alkyl group.
In formula (II), the number of carbon atoms in R ² to R ⁴ is preferably 6 or less, more preferably 3 or less, and most preferably 1. R ² to R ⁴ are preferably alkyl groups or alkenyl groups, more preferably alkyl groups.

Specific examples of the compound represented by formula (II) include, for example,
Tris (trimethylsilyl) borate, Tris (trimethoxysilyl) borate, Tris (triethylsilyl) borate, Tris (triethoxysilyl) borate, Tris (dimethylvinylsilyl) borate, Tris (diethylvinylsilyl) borate Boric acid compounds such as;
Tris (Trimethylsilyl) Phosphate, Tris (Triethylsilyl) Phosphate, Tris (Tripropylsilyl) Phosphate, Tris (Triphenylsilyl) Phosphate, Tris (Trimethoxysilyl) Phosphate, Tris (Triethoxysilyl) Phosphate , tris(triphenoxysilyl) phosphate, tris(dimethylvinylsilyl) phosphate, tris(diethylvinylsilyl) phosphate, and other phosphoric acid compounds;

Tris (trimethylsilyl) phosphite, Tris (triethylsilyl) phosphite, Tris (tripropylsilyl) phosphite, Tris (triphenylsilyl) phosphite, Tris (trimethoxysilyl) phosphite, Phosphorous acid Phosphite compounds such as tris (triethoxysilyl), tris (triphenoxysilyl) phosphite, tris (dimethylvinylsilyl) phosphite, tris (diethylvinylsilyl) phosphite;
Sulfonic acid compounds such as trimethylsilyl methanesulfonate, trimethylsilyl tetrafluoromethanesulfonate, trimethylsilyl vinylsulfonate, trimethylsilyl allylsulfonate, trimethylsilyl phenylsulfonate, triethylsilyl methanesulfonate, and triallylsilyl methanesulfonate;
is exemplified.

The compounds represented by formula (II) may be used singly, or two or more of them may be used in any combination and ratio.
The content of the compound represented by formula (II) is 0.00 in total in the non-aqueous electrolytic solution of the present invention.
1% by mass or more is preferable, but 0.01% by mass or more is more preferable, and 0.01% by mass or more is more preferable.
05% by mass or more, particularly preferably 0.1% by mass or more. Also, the upper limit is preferably 1
It is 0% by mass or less, more preferably 5% by mass or less, and still more preferably 3% by mass or less. When the content of the compound represented by formula (II) is equal to or higher than the above lower limit, the effect of improving the capacity retention rate after storage tends to increase, and by making it equal to or lower than the above upper limit, the amount of gas generated is reduced. tends to be suppressed.

[1-2. Electrolytes]
The electrolyte used in the non-aqueous electrolyte solution according to the present invention is not limited, and any known electrolyte can be employed as long as it is used as an electrolyte in a non-aqueous electrolyte secondary battery. A lithium salt is usually used as the electrolyte.
Specific examples of electrolytes include:
_LiClO4 , _LiAsF6 , _LiPF6 , _LiBF4 , _LiSbF6 , _LiSO3F
, LiN(FSO ₂ ) ₂ , etc.;
_{LiCF3SO3 , LiN ( FSO2} )( _CF3SO2 ), LiN( _CF3SO2 ) ₂
, LiN(C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,3-hexafluoropropanedisulfonylimide, lithium cyclic 1,2-tetrafluoroethanedisulfonylimide, LiN(
_{CF3SO2 ) ( C4F9SO2 )} , LiC( _{CF3SO2 ) 3} , _LiPF4 ( _CF3 )
_{2 , LiPF4} ( _{C2F5 ) 2 , LiPF4} ( _CF3SO2 ) ₂ , _LiPF4 ( _C2F5
SO2 ) ₂ , _LiBF2 ( _CF3 ) ₂ , _LiBF2 ( _C2F5 ) _{2 , LiBF2} ( _CF3
SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ and other fluorine-containing organic lithium salts;
Dicarboxylic acid-containing complex lithium salts such as lithium bis(oxalato)borate, lithium difluorooxalatoborate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate;
etc.

Among these, LiPF ₆ , LiBF ₄ , LiSO ₃ F, LiN(FSO ₂ ) ₂ , LiN(FSO ₂
)( _{CF3SO2 )} , LiN( _{CF3SO2 ) 2} , LiN( _{C2F5SO2 ) 2} , lithium bis( _oxalato )borate, lithium difluorooxalatoborate, lithium tris(oxalato)phosphate, lithium difluoro Bis(oxalato)phosphate and lithium tetrafluoro(oxalato)phosphate are preferred and LiPF ₆ , Li
_BF4 is particularly preferred.

In the present invention, LiBF ₄ , LiSO ₃ F, lithium difluorooxalatoborate, lithium difluorobis(oxalato)phosphate and lithium tetrafluoro(oxalato)phosphate are used in the non-aqueous electrolyte and in the non-aqueous electrolyte secondary battery. Including those generated by
Moreover, one of the above electrolytes may be used alone, or two or more thereof may be used in any combination and ratio. Among them, when two kinds of specific inorganic lithium salts are used together, or when an inorganic lithium salt and a fluorine-containing organic lithium salt are used together, gas generation during trickle charge is suppressed, and deterioration after high-temperature storage is suppressed. Therefore, it is preferable. In particular, _LiPF6 and _LiBF4
and inorganic lithium salts such as LiPF ₆ and LiBF ₄ and LiCF ₃ SO ₃ and LiN
(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ and other fluorine-containing organic lithium salts are preferably used in combination.

Furthermore, when LiPF ₆ and LiBF ₄ are used together, LiBF ₄ is 0 in the entire electrolyte.
. It is preferably contained at a ratio of 01% by mass or more and 50% by mass or less. The above ratio is more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more. on the other hand,
The upper limit is more preferably 20% by mass or less, still more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably 3% by mass or less. When the ratio is within the above range, the desired effect can be easily obtained, and the low degree of dissociation of LiBF ₄ makes it easy to suppress an increase in the resistance of the electrolytic solution.

On the other hand, inorganic lithium salts such as LiPF ₆ and LiBF ₄ , LiSO ₃ F, LiN (FSO
₂ ) Inorganic lithium salts such as ₂ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiN(
C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,3-hexafluoropropanedisulfonylimide, lithium cyclic 1,2-tetrafluoroethanedisulfonylimide, LiN(CF ₃ SO
₂ ) ( _{C4F9SO2 )} , LiC( _CF3SO2 ) _{3 , LiPF4 ( CF3} ) ₂ , LiP
_F4 ( _{C2F5 ) 2} , _LiPF4 ( _{CF3SO2 ) 2 , LiPF4} ( _{C2F5SO2 ) 2
, LiBF2} ( _CF3 ) ₂ , _LiBF2 ( _C2F5 ) ₂ , _LiBF2 ( _{CF3SO2 ) 2}
, LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ and other fluorine-containing organic lithium salts, lithium bis(oxalato)borate, lithium tris(oxalato)phosphate, lithium difluorooxalatoborate, lithium tri(oxalato)phosphate, lithium difluoro When a dicarboxylic acid-containing complex lithium salt such as bis(oxalato)phosphate or lithium tetrafluoro(oxalato)phosphate is used in combination, the proportion of the inorganic lithium salt in the total electrolyte is usually 70% by mass or more, preferably 80% by mass. % or more, more preferably 85 mass % or more. Moreover, it is usually 99% by mass or less, preferably 95% by mass or less.

The concentration of the electrolyte in the non-aqueous electrolytic solution is arbitrary as long as it does not impair the gist of the present invention, but is usually 0.5 mol/L or more, preferably 0.6 mol/L or more, more preferably 0.8.
mol/L or more. Also, it is usually in the range of 3 mol/L or less, preferably 2 mol/L or less, more preferably 1.8 mol/L or less, still more preferably 1.6 mol/L or less. When the concentration of the electrolyte is within the above range, the electrical conductivity of the non-aqueous electrolyte becomes sufficient,
In addition, it suppresses a decrease in electrical conductivity due to an increase in viscosity, that is, a decrease in the performance of the non-aqueous electrolyte secondary battery.

[1-3. Non-aqueous solvent]
The non-aqueous solvent contained in the non-aqueous electrolytic solution according to the present invention can be appropriately selected and used from conventionally known solvents for non-aqueous electrolytic solutions.
Examples of commonly used non-aqueous solvents include cyclic carbonates, chain carbonates, chain and cyclic carboxylic acid esters, chain ethers, phosphorus-containing organic solvents, sulfur-containing organic solvents, aromatic fluorine-containing solvents, and the like. .

Cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate, and the like. The number of carbon atoms in the cyclic carbonate is usually 3 or more and 6 or less. Among these, ethylene carbonate and propylene carbonate are preferable because they have a high dielectric constant, so that the electrolyte is easily dissolved, and the non-aqueous electrolyte secondary battery has good cycle characteristics.

Chain carbonates include dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, di-n-propyl carbonate and the like. The number of carbon atoms in the alkyl group constituting the chain carbonate is preferably 1 or more and 5 or less, and particularly preferably 1 or more and 4 or less. Among them, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferable from the viewpoint of improving battery characteristics.

Chain carbonates in which part of the hydrogen atoms in the alkyl group are substituted with fluorine are also included.
Examples of chain carbonates substituted with fluorine include bis(fluoromethyl) carbonate, bis(difluoromethyl) carbonate, bis(trifluoromethyl) carbonate, bis(2-fluoroethyl) carbonate, bis(2,2-difluoroethyl) carbonate, bis(2,2,2-trifluoroethyl) carbonate, 2-fluoroethylmethyl carbonate, 2,2-difluoroethylmethyl carbonate, 2,2,2-trifluoroethylmethyl carbonate and the like.

Chain carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and propionic acid. Isopropyl, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethyl isobutyrate, methyl valerate, ethyl valerate, methyl pivalate, ethyl pivalate, etc., and chains in which some of the hydrogen atoms in these compounds are substituted with fluorine carboxylic acid esters. Examples of chain carboxylic acid esters substituted with fluorine include methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate, and 2,2,2-trifluoroethyl trifluoroacetate.

Among these, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, methyl valerate, methyl isobutyrate, ethyl isobutyrate, and methyl pivalate It is preferable from the point of improvement of characteristics.
Cyclic carboxylic acid esters include γ-butyrolactone, γ-valerolactone, and cyclic carboxylic acid esters in which some of the hydrogen atoms in these compounds are substituted with fluorine.

Among these, γ-butyrolactone is more preferable.
Chain ethers include dimethoxymethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, diethoxymethane, 1,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxymethane, 1,1 -ethoxymethoxyethane, 1,2-ethoxymethoxyethane, and chain ethers in which some of the hydrogen atoms in these compounds are substituted with fluorine.

Examples of chain ethers substituted with fluorine include bis(trifluoroethoxy)ethane, ethoxytrifluoroethoxyethane, methoxytrifluoroethoxyethane, 1,1,1,
2,2,3,4,5,5,5-decafluoro-3-methoxy-4-trifluoromethyl-
Pentane, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-ethoxy-4
-trifluoromethyl-pentane, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-propoxy-4-trifluoromethyl-pentane, 1,1,2,2- tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl-2,2,3,3-tetrafluoropropyl ether and the like.

Among these, 1,2-dimethoxyethane and 1,2-diethoxyethane are more preferred.
Phosphorus-containing organic solvents include trimethyl phosphate, triethyl phosphate, dimethylethyl phosphate, methyldiethyl phosphate, ethylene methyl phosphate, ethylene ethyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, Examples include triphenyl phosphite, trimethylphosphine oxide, triethylphosphine oxide, triphenylphosphine oxide, and phosphorus-containing organic solvents in which some of the hydrogen atoms in these compounds are substituted with fluorine.
Examples of fluorine-substituted phosphorus-containing organic solvents include tris(2,2,2-trifluoroethyl) phosphate and tris(2,2,3,3,3-pentafluoropropyl) phosphate.

Sulfur-containing organic solvents include sulfolane, 2-methylsulfolane, 3-methylsulfolane, dimethylsulfone, diethylsulfone, ethylmethylsulfone, methylpropylsulfone, dimethylsulfoxide, methyl methanesulfonate, ethyl methanesulfonate, and methyl ethanesulfonate. , ethyl ethanesulfonate, dimethyl sulfate, diethyl sulfate, dibutyl sulfate, etc., and sulfur-containing organic solvents obtained by substituting a portion of hydrogen in these compounds with fluorine.

Examples of aromatic fluorine-containing solvents include fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and benzotrifluoride.
Among the above non-aqueous solvents, it is preferable to use ethylene carbonate and/or propylene carbonate, which are cyclic carbonates, and the combined use of these and chain carbonates can achieve both high electrical conductivity and low viscosity of the electrolytic solution. preferred from

One type of non-aqueous solvent may be used alone, or two or more types may be used together in any combination and ratio. When two or more types are used in combination, for example, when a cyclic carbonate and a chain carbonate are used in combination, the preferred content of the chain carbonate in the non-aqueous solvent is usually 20% by volume or more, preferably 40% by volume or more, Moreover, it is usually 95% by volume or less, preferably 90% by volume or less. On the other hand, the preferred content of the cyclic carbonate in the non-aqueous solvent is usually 5% by volume or more, preferably 10% by volume or more, and usually 80% by volume or less, preferably 60% by volume or less. When the ratio of the chain carbonate is within the above range, the viscosity increase of the non-aqueous electrolytic solution is suppressed, and the decrease in the electrical conductivity of the non-aqueous electrolytic solution due to the decrease in the degree of dissociation of the lithium salt as the electrolyte is suppressed. In the present specification, the volume of the non-aqueous solvent is the measured value at 25°C, but the measured value at the melting point is used for ethylene carbonate, which is solid at 25°C.

[1-4. Other additives]
Various additives may be contained within a range that does not significantly impair the effects of the present invention.
Any conventionally known additive can be used as the additive. In addition, an additive may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
As for the mass ratio of the compound represented by the formula (II) and other additives, the "mass of the compound represented by the formula (II) / the mass of the other additives" is usually 0.01. or more, preferably 0.05 or more, more preferably 0, 10 or more, still more preferably 0.20, particularly preferably 0.50 or more, most preferably 1 or more, usually 10, preferably 50 , more preferably 10 or less, still more preferably 5 or less, and particularly preferably 2 or less.
Within this range, the battery characteristics, particularly the capacity, capacity recovery rate and capacity retention rate after high temperature storage can be increased, and the amount of gas generated can be reduced. Although the principle of this is not clear, it is believed that side reactions of the additive on the electrode can be minimized by mixing at this ratio.

Conventionally known additives that can be added to the non-aqueous electrolytic solution according to the present invention include carbon-
Cyclic carbonates having carbon unsaturated bonds, fluorine-containing cyclic carbonates, compounds having an isocyanato group (isocyanate group), sulfur-containing organic compounds, phosphorus-containing organic compounds, organic compounds having a cyano group, silicon-containing compounds, aromatic compounds, fluorine Non-containing carboxylic acid esters, cyclic compounds having multiple ether bonds, compounds having an isocyanuric acid skeleton, monofluorophosphates, difluorophosphates, borates, oxalates, fluorosulfonates and the like can be mentioned.
Each additive will be described below, but some of them may include the ones already mentioned above.

[1-4-1. Cyclic carbonate having a carbon-carbon unsaturated bond]
Cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter, "unsaturated cyclic carbonate"
) is not particularly limited as long as it is a cyclic carbonate having a carbon-carbon double bond or a carbon-carbon triple bond, and any unsaturated carbonate can be used. A cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate.

Examples of unsaturated cyclic carbonates include vinylene carbonates, ethylene carbonates substituted with substituents having aromatic rings or carbon-carbon double bonds or carbon-carbon triple bonds, phenyl carbonates, vinyl carbonates, allyl carbonates, catechol carbonates and the like.
Among them, unsaturated cyclic carbonates particularly preferable for combined use include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4,5- diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-
divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, and 4-vinyl-5-ethynylethylene carbonate. Further, vinylene carbonate, vinylethylene carbonate and ethynylethylene carbonate are preferred because they form a more stable surface protective film, vinylene carbonate and vinylethylene carbonate are more preferred, and vinylene carbonate is even more preferred.

The molecular weight of the unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as it does not significantly impair the effects of the present invention. The molecular weight is preferably 80 or more, more preferably 85 or more,
Also, it is preferably 250 or less, more preferably 150 or less. Within this range, it is easy to ensure the solubility of the unsaturated cyclic carbonate in the non-aqueous electrolytic solution, and the effects of the present invention are easily exhibited.

The method for producing the unsaturated cyclic carbonate is not particularly limited, and any known method can be selected for production.
The unsaturated cyclic carbonates may be used singly or in combination of two or more in any desired ratio. Moreover, the content of the unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as it does not significantly impair the effects of the present invention. The content of the unsaturated cyclic carbonate is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, more preferably 0.1% by mass or more, in 100% by mass of the non-aqueous electrolytic solution 0.5% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 4% by mass or less, even more preferably 3% by mass or less, and particularly preferably 2% by mass or less. be. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient effect of improving cycle characteristics, and has good high-temperature storage characteristics, a small amount of gas generation, and a good discharge capacity retention rate. .

[1-4-2. Fluorine-containing cyclic carbonate]
Examples of the fluorine-containing cyclic carbonate include fluorinated cyclic carbonates having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof. For example, fluorinated ethylene carbonate (hereinafter referred to as "fluorinated ethylene carbonate") sometimes),
and derivatives thereof. Derivatives of fluorinated ethylene carbonate include fluorinated ethylene carbonate substituted with an alkyl group having 1 to 4 carbon atoms. Among them, fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof are preferable.

By adding a fluorine-containing cyclic carbonate, high-temperature storage characteristics and cycle characteristics can be improved in a battery using this electrolytic solution.
Fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4, 5-
difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4-(fluoromethyl)-ethylene carbonate, 4-(difluoromethyl)-ethylene carbonate, 4-
(trifluoromethyl)-ethylene carbonate, 4-(fluoromethyl)-4-fluoroethylene carbonate, 4-(fluoromethyl)-5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5 -difluoro-4,5
-dimethylethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate, and the like.

Among them, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are preferred because they impart high ionic conductivity to the electrolytic solution and easily form a stable interfacial protective coating.
One of the fluorinated cyclic carbonates may be used alone, or two or more of them may be used in any combination and ratio. The amount of fluorinated cyclic carbonate (the total amount when two or more kinds are used) is preferably 0.001% by mass or more, more preferably 0.0% in 100% by mass of the electrolytic solution.
1% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, most preferably 1.2% by mass or more, and preferably It is 10% by mass or less, more preferably 7% by mass or less, still more preferably 5% by mass or less, particularly preferably 3% by mass or less, and most preferably 2% by mass or less. When the fluorinated cyclic carbonate is used as the non-aqueous solvent, the content is preferably 1% by volume or more, more preferably 5% by volume or more, and still more preferably 10% by volume or more in 100% by volume of the non-aqueous solvent. Also, it is preferably 50% by volume or less, more preferably 35% by volume or less, and still more preferably 25% by volume or less.
By using the above content, it is possible to sufficiently obtain the effect of improving high-temperature storage characteristics and cycle characteristics, and suppress unnecessary gas generation.

[1-4-3. Compound having an isocyanato group]
The non-aqueous electrolytic solution can contain a compound having an isocyanato group (isocyanate group). Hereinafter, it may be referred to as an "isocyanate compound".
The isocyanate compound is not particularly limited as long as it is an organic compound having at least one isocyanate group in the molecule, but the number of isocyanate groups in one molecule is preferably 1
4 or less, more preferably 1 or more and 3 or less, still more preferably 1 or more and 2 or less.

The isocyanate compound is preferably a linear or branched alkylene group, a cycloalkylene group, a structure in which a cycloalkylene group and an alkylene group are linked, an aromatic hydrocarbon group,
A structure in which an aromatic hydrocarbon group and an alkylene group are linked, an ether structure (-O-), a structure in which an ether structure (-O-) and an alkylene group are linked, a carbonyl group (-C(=O)-), a carbonyl group and an alkylene group, a sulfonyl group (-S(=O)-), a structure in which a sulfonyl group and an alkylene group are linked, or a compound in which an isocyanate group is bonded to a compound having a halogenated structure, etc. and more preferably a linear or branched alkylene group, a cycloalkylene group, a structure in which a cycloalkylene group and an alkylene group are linked,
A compound in which an isocyanate group is bonded to an aromatic hydrocarbon group or a structure in which an aromatic hydrocarbon group and an alkylene group are linked, more preferably a compound in which an isocyanate group is bonded to a structure in which a cycloalkylene group and an alkylene group are linked. be. There are no particular restrictions on the molecular weight of the isocyanate compound. The molecular weight is preferably 80 or more, more preferably 115 or more,
It is more preferably 170 or more, 300 or less, and more preferably 230 or less. Within this range, it is easy to ensure the solubility of the isocyanate compound in the non-aqueous electrolytic solution, and the effects of the present invention are likely to be exhibited. The method for producing the isocyanate compound is not particularly limited, and any known method can be selected for production. Moreover, you may use a commercial item.

As an isocyanate compound,
Examples of compounds having one isocyanato group include methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate,
Alkyl isocyanates such as tert-butyl isocyanate, cycloalkyl isocyanates such as cyclohexyl isocyanate, unsaturated isocyanates such as allyl isocyanate and propargyl isocyanate, aromatic isocyanates such as phenyl isocyanate, trifluoromethylphenyl isocyanate and p-toluenesulfonyl isocyanate;

Examples of compounds having two isocyanato groups include monomethylene diisocyanate, dimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, 1,4-diisocyanato-2-butene, toluene diisocyanate, xylene diisocyanate, 1 , 3
-bis(isocyanatomethyl)cyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-4,4'-diisocyanate, bicyclo[2.2.1]heptane-2,5-diylbis(methylisocyanate), bicyclo[ 2.2.1] Compounds such as heptane-2,6-diylbis(methyl isocyanate), isophorone diisocyanate, carbonyl diisocyanate, 1,4-diisocyanatobutane-1,4-dione, trimethylhexamethylene diisocyanate;

As compounds having three isocyanato groups, 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylene diisocyanate, 1,3,5-
triisocyanatomethylbenzene, 1,3,5-tris(6-isocyanatohexa-1
-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimeric compounds derived from compounds having at least two isocyanate groups in the molecule (e.g. biuret , isocyanurates, adducts and modified polyisocyanates of difunctional type, etc.);
etc.

Among these, t-butyl isocyanate, cyclohexyl isocyanate, p-toluenesulfonyl isocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane-4,4'- diisocyanate, bicyclo [2.
2.1] heptane-2,5-diylbis(methyl isocyanate), bicyclo [2.2.
1] Compounds such as heptane-2,6-diylbis(methyl isocyanate), isophorone diisocyanate, and trimethylhexamethylene diisocyanate are preferred from the viewpoint of improving storage characteristics. , 3-bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bicyclo[2.2.1]heptane-
2,5-diylbis(methyl isocyanate), bicyclo[2.2.1]heptane-2,
6-diylbis(methyl isocyanate), isophorone diisocyanate, trimethylhexamethylene diisocyanate are more preferred, cyclohexyl isocyanate, p-toluenesulfonyl isocyanate, hexamethylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane- 4,4′-diisocyanate, bicyclo[2.2.1]heptane-2,5-diylbis(methylisocyanate),
More preferred is bicyclo[2.2.1]heptane-2,6-diylbis(methyl isocyanate).

One isocyanate compound may be used alone, or two or more of them may be used in any combination and ratio.
The amount of the isocyanate compound (the total amount when two or more types are used) is usually 0.001% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass in 100% by mass of the electrolytic solution. or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

[1-4-4. Sulfur-containing organic compound]
The sulfur-containing organic compound is not particularly limited as long as it is an organic compound having at least one sulfur atom in the molecule, but is preferably an organic compound having an S=O group in the molecule, and a chain linear sulfonates, cyclic sulfonates, chain sulfates, cyclic sulfates, chain sulfites and cyclic sulfites. However, those corresponding to fluorosulfonates are not sulfur-containing organic compounds described later, but are included in fluorosulfonates that are electrolytes described later, and those corresponding to silyl ester compounds are not sulfur-containing organic compounds described later. , are included in the aforementioned silyl ester compounds.

Among them, chain sulfonates, cyclic sulfonates, chain sulfates, cyclic sulfates, chain sulfites and cyclic sulfites are preferred, and compounds having _two S(=O) groups are more preferred.
Chain sulfonate esters and cyclic sulfonate esters are more preferred, and cyclic sulfonate esters are more preferred. Specific compounds of chain sulfonates, cyclic sulfonates, chain sulfates, cyclic sulfates, chain sulfites and cyclic sulfites are exemplified below.

<Chain sulfonic acid ester>
fluorosulfonic acid esters such as methyl fluorosulfonate and ethyl fluorosulfonate;
Methanesulfonic acid esters such as methyl methanesulfonate, ethyl methanesulfonate, busulfan, methyl 2-(methanesulfonyloxy)propionate, ethyl 2-(methanesulfonyloxy)propionate and ethyl methanesulfonyloxyacetate.

methyl vinylsulfonate, ethyl vinylsulfonate, allyl vinylsulfonate, propargyl vinylsulfonate, methyl allylsulfonate, ethyl allylsulfonate, allyl allylsulfonate, propargyl allylsulfonate and 1,2-bis(vinylsulfonyloxy ) alkenyl sulfonic acid esters such as ethane.
Methoxycarbonylmethyl methanedisulfonate, Ethoxycarbonylmethyl methanedisulfonate, Methoxycarbonylmethyl 1,2-ethanedisulfonate, Ethoxycarbonylmethyl 1,2-ethanedisulfonate, Methoxycarbonylmethyl 1,3-propanedisulfonate, 1,3 - Alkyl disulfonic acid esters such as ethoxycarbonylmethyl propanedisulfonate and 1-methoxycarbonylethyl 1,3-propanedisulfonate.

<Cyclic sulfonate>
1,3-propanesultone, 1-fluoro-1,3-propanesultone, 2-fluoro-1,3-propanesultone, 3-fluoro-1,3-propanesultone, 1-methyl-
1,3-propanesultone, 2-methyl-1,3-propanesultone, 3-methyl-1,
3-propanesultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 2-methyl-1-propene-1,3-sultone, 1,4-butanesultone and 1,
sultone compounds such as 5-pentane sultone;

disulfonate compounds such as methylene methane disulfonate and ethylene methane disulfonate;
nitrogen-containing compounds such as 1,2,3-oxathiazolidine-2,2-dioxide;
phosphorus-containing compounds such as 1,2,3-oxathiaphoslane-2,2-dioxide;

<Chain sulfate ester>
Dialkylsulfate compounds such as dimethylsulfate, ethylmethylsulfate and diethylsulfate.

<Cyclic sulfate>
1,2-ethylene sulfate, 1,2-propylene sulfate, 1,3-propylene sulfate, 1,2-butylene sulfate, 1,3-butylene sulfate, 1,
Alkylene sulfate compounds such as 4-butylene sulfate, 1,2-pentylene sulfate, 1,3-pentylene sulfate, 1,4-pentylene sulfate and 1,5-pentylene sulfate.

<Chain sulfite ester>
dialkyl sulfite compounds such as dimethyl sulfite, ethyl methyl sulfite and diethyl sulfite;

<Cyclic sulfite>
1,2-ethylene sulfite, 1,2-propylene sulfite, 1,3-propylene sulfite, 1,2-butylene sulfite, 1,3-butylene sulfite, 1,
Alkylene sulfite compounds such as 4-butylene sulfite, 1,2-pentylene sulfite, 1,3-pentylene sulfite, 1,4-pentylene sulfite and 1,5-pentylene sulfite.

Of these, methyl 2-(methanesulfonyloxy)propionate, ethyl 2-(methanesulfonyloxy)propionate, 2-(methanesulfonyloxy)propionate 2
-propynyl, 1-methoxycarbonylethyl propanedisulfonate, 1-ethoxycarbonylethyl propanedisulfonate, 1-methoxycarbonylethyl butanedisulfonate, 1-ethoxycarbonylethyl butanedisulfonate, 1,3-propanesultone, 1-
Propene-1,3-sultone, 1,4-butanesultone, 1,2-ethylenesulfate, 1,2-ethylenesulfite, methyl methanesulfonate and ethyl methanesulfonate are preferred from the viewpoint of improving the initial efficiency, and propanedisulfone 1-methoxycarbonylethyl acid, 1-ethoxycarbonylethyl propanedisulfonate, 1-methoxycarbonylethyl butanedisulfonate, 1-ethoxycarbonylethyl butanedisulfonate, 1,3-propanesultone, 1-propene-1,3-sultone , 1,2-ethylene sulfate and 1
,2-ethylene sulfite is more preferred, and 1,3-propanesultone and 1-propene-1,3-sultone are even more preferred.

Sulfur-containing organic compounds may be used singly, or two or more of them may be used in any combination and ratio.
The content of the sulfur-containing organic compound (total amount in the case of two or more kinds) is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 100% by mass of the non-aqueous electrolyte 0.1% by mass or more, particularly preferably 0.3% by mass or more, particularly preferably 0.6% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably is 3% by mass or less, more preferably 2% by mass or less, particularly preferably 1.5% by mass or less,
Most preferably, it is 1.0% by mass or less. Within this range, the output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, etc. of the battery can be easily controlled.

[1-4-5. Phosphorus-containing organic compound]
The phosphorus-containing organic compound is not particularly limited as long as it is an organic compound having at least one phosphorus atom in the molecule. A battery using a non-aqueous electrolyte containing a phosphorus-containing organic compound is
Durability can be improved.
As the phosphorus-containing organic compound, phosphate, phosphonate, phosphinate and phosphite are preferred, phosphate and phosphonate are more preferred, and phosphonate is even more preferred. These esters may have a substituent.

Specific examples of phosphorus-containing organic compounds include:
Diethyl vinyl phosphate, allyl diethyl phosphate, propargyl diethyl phosphate, trivinyl phosphate, triallyl phosphate, tripropargyl phosphate, diallyl ethyl phosphate, dipropargyl ethyl phosphate, 2-acryloyloxyethyl diethyl phosphate, tris(2-acryloyloxyethyl) phosphate , trimethylphosphonoformate, methyl diethylphosphonoformate, methyl dipropylphosphonoformate, methyl dibutylphosphonoformate, triethyl phosphonoformate, ethyl dimethylphosphonoformate, ethyl dipropylphosphonoformate, Ethyl dibutylphosphonoformate, tripropyl phosphonoformate, propyl dimethylphosphonoformate, propyl diethylphosphonoformate, propyl dibutylphosphonoformate, tributyl phosphonoformate, butyl dimethylphosphonoformate, butyl diethyl phosphonoformate, butyl dipropylphosphonoformate, methyl bis(2,
2,2-trifluoroethyl)phosphonoformate, ethyl bis(2,2,2-trifluoroethyl)phosphonoformate, propyl bis(2,2,2-trifluoroethyl)phosphonoformate, butyl Bis(2,2,2-trifluoroethyl)phosphonoformate, trimethylphosphonoacetate, methyl diethylphosphonoacetate, methyl dipropylphosphonoacetate, methyl dibutylphosphonoacetate, triethylphosphonoacetate, ethyl dimethylphosphonoacetate Acetate, ethyl dipropylphosphonoacetate, ethyl dibutylphosphonoacetate, tripropyl phosphonoacetate, propyl dimethylphosphonoacetate, propyl diethylphosphonoacetate, propyl dibutylphosphonoacetate, tributyl phosphonoacetate,
Butyl dimethylphosphonoacetate, butyl diethylphosphonoacetate, butyl
dipropylphosphonoacetate, methyl bis(2,2,2-trifluoroethyl)phosphonoacetate, ethyl bis(2,2,2-trifluoroethyl)phosphonoacetate, propyl bis(2,2,2-trifluoroethyl)phosphonoacetate fluoroethyl)phosphonoacetate, butyl bis(2,2,2-trifluoroethyl)phosphonoacetate, allyl dimethylphosphonoacetate, allyl diethylphosphonoacetate, 2-propynyl dimethylphosphonoacetate, 2-propynyl diethylphosphonoacetate Acetate, Trimethyl 3-phosphonopropionate, Methyl 3-(diethylphosphono)propionate, Methyl 3-(dipropylphosphono)propionate, Methyl 3-(dibutylphosphono)propionate, Triethyl 3-phosphonopropionate , ethyl 3-(dimethylphosphono)propionate, ethyl 3-(dipropylphosphono)propionate, ethyl 3-(dibutylphosphono)propionate, tripropyl 3-phosphonopropionate, propyl
3-(dimethylphosphono)propionate, propyl 3-(diethylphosphono)propionate, propyl 3-(dibutylphosphono)propionate, tributyl 3-phosphonopropionate, butyl 3-(dimethylphosphono)propionate, butyl 3 -
(diethylphosphono)propionate, butyl 3-(dipropylphosphono)propionate, methyl 3-(bis(2,2,2-trifluoroethyl)phosphono)propionate, ethyl 3-(bis(2,2,2- trifluoroethyl)phosphono)propionate, propyl 3-(bis(2,2,2-trifluoroethyl)phosphono)propionate, butyl 3-(bis(2,2,2-trifluoroethyl)phosphono)propionate,
trimethyl 4-phosphonobutyrate, methyl 4-(diethylphosphono)butyrate,
methyl 4-(dipropylphosphono)butyrate, methyl 4-(dibutylphosphono)butyrate, triethyl 4-phosphonobutyrate, ethyl 4-(dimethylphosphono)butyrate, ethyl 4-(dipropylphosphono)butyrate, Ethyl 4-(dibutylphosphono)butyrate, tripropyl 4-phosphonobutyrate, propyl 4-(dimethylphosphono)butyrate, propyl 4-(diethylphosphono)butyrate, propyl
4-(dibutylphosphono)butyrate, tributyl 4-phosphonobutyrate, butyl
4-(dimethylphosphono)butyrate, butyl 4-(diethylphosphono)butyrate,
Butyl 4-(dipropylphosphono)butyrate and the like.

One of the phosphorus-containing organic compounds may be used alone, or two or more of them may be used in any combination and ratio.
The content of the phosphorus-containing organic compound (the total amount in the case of two or more types) is, in 100% by mass of the electrolyte,
It is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.01% by mass or more.
1% by mass or more, more preferably 0.4% by mass or more, particularly preferably 0.6% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass Below, more preferably 2% by mass or less, particularly preferably 1.2% by mass or less, and most preferably 0.9% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

[1-4-6. Organic compound having a cyano group]
Examples of organic compounds having a cyano group include pentanenitrile, octanenitrile, decanenitrile, dodecanenitrile, crotononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, glutaronitrile and 3,9-bis(2 -cyanoethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,2,3-tricyanopropane, 1,3,5-tricyanopentane, 1,4,7-tricyano heptane, 1,2,4-tricyanobutane, 1,2,5-tricyanopentane,
1,2,6-tricyanohexane, 1,3,6-tricyanohexane, and 1,2,7-tricyanoheptane.

The organic compound having a cyano group is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and particularly preferably 0.3% by mass in 100% by mass of the electrolytic solution. It is contained at a concentration of not less than 10% by mass and usually not more than 10% by mass, preferably not more than 5% by mass, more preferably not more than 3% by mass, and particularly preferably not more than 2% by mass. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.
An organic compound having a cyano group may be used singly, or two or more of them may be used in any combination and ratio.

[1-4-7. Silicon-containing compound]
If the silicon-containing compound is a compound having at least one silicon atom in the molecule,
There are no particular restrictions. In the non-aqueous electrolytic solution according to the present invention, durability characteristics can be improved by using a silicon-containing compound in combination.
As the silicon-containing compound, a compound represented by the following formula (2-6) is preferable.

In formula (2-6), R ⁶¹ , R ⁶² and R ⁶³ are each independently a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and X ⁶¹ is an oxygen atom or a nitrogen atom. and an organic group containing at least one atom selected from the group consisting of silicon atoms.
R ⁶¹ , R ⁶² and R ⁶³ are preferably hydrogen atom, fluorine atom, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group,
It is a tert-butyl group or a phenyl group, more preferably a methyl group.

X ⁶¹ is an organic group containing at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom and a silicon atom, preferably an organic group containing at least an oxygen atom or a silicon atom. Here, the organic group is a group composed of one or more atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, silicon atoms, sulfur atoms, phosphorus atoms and halogen atoms. show. Examples of organic groups include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, alkoxy groups, CN groups, isocyanato groups, fluoro groups, alkylsulfonic acid groups and trialkylsilyl groups. A part of the monovalent organic group may be substituted with a fluorine atom. The number of carbon atoms in the organic group is 1 or more, preferably 3 or more, more preferably 5 or more, and usually 15 or less, preferably 12 or less, more preferably 8 or less.

Among these, alkylsulfonic acid groups, trialkylsilyl groups, boric acid groups, phosphoric acid groups and phosphorous acid groups are preferred.
As a silicon-containing compound,
tris(trimethylsilyl)borate, tris(trimethoxysilyl)borate, tris(triethylsilyl)borate, tris(triethoxysilyl)borate, tris(dimethylvinylsilyl)borate and tris(diethylvinylsilyl)borate Boric acid compounds such as; tris phosphate (trimethylsilyl), tris phosphate (triethylsilyl), tris phosphate (
tripropylsilyl), tris(triphenylsilyl) phosphate, tris(trimethoxysilyl) phosphate, tris(triethoxysilyl) phosphate, tris(triphenoxysilyl) phosphate, tris(dimethylvinylsilyl) phosphate , phosphoric acid compounds such as tris(diethylvinylsilyl) phosphate;

Tris (trimethylsilyl) phosphite, Tris (triethylsilyl) phosphite, Tris (tripropylsilyl) phosphite, Tris (triphenylsilyl) phosphite, Tris (trimethoxysilyl) phosphite, Phosphorous acid Phosphite compounds such as tris (triethoxysilyl), tris (triphenoxysilyl) phosphite, tris (dimethylvinylsilyl) phosphite, tris (diethylvinylsilyl) phosphite;
Sulfonic acid compounds such as trimethylsilyl methanesulfonate and trimethylsilyl tetrafluoromethanesulfonate;
hexamethyldisilane, hexaethyldisilane, 1,1,2,2-tetramethyldisilane, 1,1,2,2-tetraethyldisilane, 1,2-diphenyltetramethyldisilane, 1,1,2,2-tetraphenyl disilane compounds such as disilane;
etc.

Among these, tris(trimethylsilyl) borate, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, trimethylsilyl methanesulfonate, trimethylsilyl tetrafluoromethanesulfonate, hexamethyldisilane, hexaethyldisilane, 1,2- Diphenyltetramethyldisilane and 1,1,2,2-tetraphenyldisilane are preferred, and tris(trimethylsilyl) borate, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite and hexamethyldisilane are more preferred.

One of these silicon-containing compounds may be used alone, or two or more of them may be used in any combination and ratio.
The silicon-containing compound (the total amount in the case of two or more types) is usually 0.0 in 100% by mass of the electrolyte
01% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3
% by mass or less. Within this range, output characteristics, load characteristics, low temperature characteristics, cycle characteristics,
Easy to control high-temperature storage characteristics.

[1-4-8. Aromatic compound]
The aromatic compound is not particularly limited as long as it is an organic compound having at least one aromatic ring in the molecule.
Examples of aromatic compounds include the following.
fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, benzotrifluoride, cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, diphenyl carbonate, methylphenyl carbonate, 2-phenyl acetate Ethyl, 3-phenylpropyl acetate, methyl phenylacetate, ethyl phenylacetate, 2-phenylethyl phenylacetate, 3-phenylpropyl phenylacetate, methyl 3-phenylpropionate, ethyl 3-phenylpropionate, 3-phenylpropionate 2 -phenylethyl, 3-phenylpropyl 3-phenylpropionate, methylphenylsulfonate, 2-tert-butylphenylmethylsulfonate, 4-tert-butylphenylmethylsulfonate,
cyclohexylphenylmethylsulfonate, trimethylphenylsilane, tris(2-
tert-butylphenyl)phosphate, tris(4-tert-butylphenyl)phosphate, tris(2-cyclohexylphenyl)phosphate, tris(4-cyclohexylphenyl)phosphate, diethylphenylphosphonate, diethylbenzylphosphonate, diethyl-(4-fluoro benzyl)phosphonate, 2-fluorophenylacetate, 4-fluorophenylacetate, 2,4-difluoroanisole, 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene.

Among them, fluorobenzene, benzotrifluoride, cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, diphenyl carbonate,
methylphenyl carbonate, 2-phenylethyl phenylacetate, 4-tert-butylphenylmethylsulfonate, cyclohexylphenylmethylsulfonate, tris(2
-tert-butylphenyl) phosphate, tris(4-tert-butylphenyl)
phosphates, tris(4-cyclohexylphenyl)phosphate, 2,4-difluoroanisole and 2-fluorotoluene.

In addition to the above,
1-phenyl-1,3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl-1-(2-methyl-2-phenylpropyl)-3-phenyl-1H-indane, 1-phenyl-1 , 3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl-1-(
2-methyl-2-phenylpropyl)-3-phenyl-1H-indane, 2,2-diphenylbutane, 3,3-diphenylpentane, 3,3-diphenylhexane, 4,4-diphenylheptane, 5,5- diphenyloctane, 6,6-diphenylnonane, 1,1-diphenyl-1,1-ditert-butyl-methane, 1,1-diphenylcyclohexane,
1,1-diphenylcyclopentane, 1,1-diphenyl-4-methylcyclohexane.

1,3-bis(1-methyl-1-phenylethyl)-benzene, 1,4-bis(1-methyl-1-phenylethyl)-benzene, 1-phenyl-1,3,3-trimethylindane, 2 ,2-diphenylbutane, 3,3-diphenylpentane, 1,1-diphenyl-1
, 1-ditert-butyl-methane, 1,1-diphenylcyclohexane, 1,1-diphenylcyclopentane, 1,1-diphenyl-4-methylcyclohexane, 1,3-bis(1-methyl-1-phenylethyl )-benzene, 1,4-bis(1-methyl-1-phenylethyl)-benzene, 1-phenyl-1,3,3-trimethylindane, 2,2-diphenylbutane, 1,1-diphenylcyclohexane, 1 , 1-diphenyl-4-methylcyclohexane, 1,3-bis(1-methyl-1-phenylethyl)-benzene, 1,4
-bis(1-methyl-1-phenylethyl)-benzene, 1-phenyl-1,3,3-trimethylindane, 1,1-diphenylcyclohexane, 1,1-diphenyl-4-methylcyclohexane, 1,3- bis(1-methyl-1-phenylethyl)-benzene, 1,
4-bis(1-methyl-1-phenylethyl)-benzene, 1-phenyl-1,3,3-
trimethylindane, 1,1-diphenylcyclohexane, 1,3-bis(1-methyl-
1-phenylethyl)-benzene, 1,4-bis(1-methyl-1-phenylethyl)-
Benzene, 1-phenyl-1,3,3-trimethylindane, 1-phenyl-1,3,3
-trimethylindane and the like.

An aromatic compound may be used independently or may use 2 or more types together. Total amount of non-aqueous electrolyte (1
00% by mass), the amount of the aromatic compound (the total amount in the case of two or more types) is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.05% by mass. above, more preferably 0.1% by mass or more, more preferably 0.4% by mass or more, and usually 1
It is 0% by mass or less, preferably 8% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and particularly preferably 2.5% by mass or less. By being within the above range, the effects of the present invention can be easily exhibited, and an increase in the resistance of the battery can be prevented.

[1-4-9. Fluorine-free carboxylic acid ester]
Fluorine-free carboxylic acid esters can also be used as solvents as described above. The fluorine-free carboxylic acid ester is not particularly limited as long as it is a carboxylic acid ester having no fluorine atom in the molecule.
Examples of fluorine-free chain carboxylic acid esters include the following.

methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate,
Ethyl propionate, n-propyl propionate, n-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, n-butyl butyrate, methyl valerate, ethyl valerate, n-propyl valerate, n- valerate Butyl, methyl pivalate, ethyl pivalate, n-propyl pivalate, n-butyl pivalate.

Among these, from the viewpoint of improving the ionic conductivity by reducing the viscosity of the electrolyte, -Butyl is more preferred, methyl propionate, ethyl propionate, n-propyl propionate and n-butyl propionate are more preferred, and ethyl propionate and n-propyl propionate are particularly preferred.

Fluorine-free carboxylic acid esters may be used alone, or two or more of them may be used in any combination and ratio.
The amount of the fluorine-free carboxylic acid ester (the total amount in the case of two or more types) is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0 in 100% by mass of the electrolyte solution. .1% by mass or more, more preferably 0.3% by mass or more, particularly preferably 0.6% by mass
The content is generally 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and particularly preferably 1% by mass or less.
In addition, when a fluorine-free carboxylic acid ester is used as a non-aqueous solvent, the content is preferably 1% by volume or more, more preferably 5% by volume or more, and still more preferably 10% by volume or more in 100% by volume of the non-aqueous solvent. , Still more preferably 20% by volume or more, and usually 50% by volume
Below, more preferably 45% by volume or less, still more preferably 40% by volume or less. Within such a range, an increase in negative electrode resistance can be suppressed, and output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics can be easily controlled.

[1-4-10. Cyclic compound having multiple ether bonds]
The cyclic compound having multiple ether bonds is not particularly limited as long as it is a cyclic compound having multiple ether bonds in the molecule. Cyclic compounds with multiple ether bonds are
It contributes to the improvement of the high-temperature storage characteristics of the battery, and can improve the durability characteristics of the non-aqueous electrolyte secondary battery.

Cyclic compounds having multiple ether bonds include tetrahydrofuran, methyltetrahydrofuran, tetrahydropyran, methyltetrahydropyran, and the like.
A cyclic compound having a plurality of ether bonds may be used alone, or two or more of them may be used in any combination and ratio. The amount of the cyclic compound having a plurality of ether bonds (total amount in the case of two or more types) is usually 0.001% by mass or more, preferably 0.01% by mass or more, and more preferably 100% by mass of the electrolytic solution. is 0.1% by mass or more, particularly preferably 0.3% by mass or more, and is usually 10% by mass or less, preferably 5% by mass or less,
It is more preferably 3% by mass or less, still more preferably 2% by mass or less. When the above range is satisfied, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

[1-4-11. A compound having an isocyanuric acid skeleton]
Examples of compounds having an isocyanuric acid skeleton include the following.
trivinyl isocyanurate, tri(1-propenyl) isocyanurate, triallyl isocyanurate, trimethallyl isocyanurate, methyl diallyl isocyanurate,
Ethyl diallyl isocyanurate, diethyl allyl isocyanurate, diethyl vinyl isocyanurate, tri(propargyl) isocyanurate, tris(2-acryloxymethyl) isocyanurate, tris(2-acryloxyethyl) isocyanurate, tris(2-methacryloxy methyl)isocyanurate, tris(2-methacryloxyethyl)
isocyanurate, ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate, among others, triallyl isocyanurate, trimethallyl isocyanurate, tris(2-acryloxyethyl) isocyanurate, tris(2-methacrylic tris-(2-acryloxyethyl) isocyanurate and ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate, triallyl isocyanurate and tris(2-
Acryloxyethyl)isocyanurate is particularly preferred because it has a large effect of improving continuous charge characteristics. These may be used alone or in combination of two or more.

The content of the compound having an isocyanuric acid skeleton (the total amount in the case of two or more types) is preferably 0.01% by mass or more in 100% by mass of the non-aqueous electrolyte, and contains 0.1% by mass or more. is more preferable, and it is most preferable to contain 0.2% by mass or more. Also, the content is preferably 5% by mass or less, more preferably 3% by mass or less, and most preferably 2% by mass or less. By using the above content, it is possible to sufficiently obtain the effect of improving high-temperature storage characteristics and continuous charging characteristics, and to suppress an unnecessary increase in resistance.

[1-4-12. Additives that are electrolytes]
Among additives, the following additives (monofluorophosphates, difluorophosphates, borates, oxalates and fluorosulfonates) can be exemplified as additives that play a role as electrolytes. These salts are particularly preferably lithium salts.
The total content of borate, oxalate and fluorosulfonate in the non-aqueous electrolytic solution is preferably 0.01% by mass or more, particularly preferably 0.1% by mass or more. Moreover, it is preferably 20% by mass or less, and particularly preferably 10% by mass or less.

[1-4-12-1. monofluorophosphate, difluorophosphate]
Monofluorophosphates and difluorophosphates are not particularly limited as long as they are salts having at least one monofluorophosphoric acid or difluorophosphoric acid structure in the molecule, respectively. By using an electrolytic solution containing one or more selected from monofluorophosphate and difluorophosphate, the durability characteristics of the non-aqueous electrolyte secondary battery can be improved. In addition, by applying it to a non-aqueous secondary battery equipped with a specific positive electrode described later, the capacity retention rate after high temperature storage is high,
It is possible to obtain a highly safe non-aqueous electrolyte secondary battery with a small amount of stored gas after high-temperature storage, little metal elution from the positive electrode, and high safety.

Counter cations in monofluorophosphates and difluorophosphates are not particularly limited, and include lithium, sodium, potassium, magnesium, calcium, NR ¹²¹ R
¹²² R ¹²³ R ¹²⁴ (wherein R ¹²¹ to R ¹²⁴ are each independently a hydrogen atom or an organic group having 1 to 12 carbon atoms) and the like. The organic group having 1 to 12 carbon atoms represented by R ¹²¹ to R ¹²⁴ of the ammonium is not particularly limited, and for example, an alkyl group optionally substituted with a fluorine atom, a halogen atom or an alkyl group substituted with a cycloalkyl group which may be substituted, an aryl group which may be substituted with a halogen atom or an alkyl group, a nitrogen atom-containing heterocyclic group which may have a substituent, and the like.
Among them, R ¹²¹ to R ¹²⁴ are preferably each independently a hydrogen atom, an alkyl group, a cycloalkyl group, a nitrogen atom-containing heterocyclic group, or the like. The counter cation is preferably lithium, sodium or potassium, with lithium being particularly preferred.

Examples of monofluorophosphates and difluorophosphates include lithium monofluorophosphate, sodium monofluorophosphate, potassium monofluorophosphate, lithium difluorophosphate, sodium difluorophosphate, potassium difluorophosphate, etc. Lithium monofluorophosphate and lithium difluorophosphate are preferred, and lithium difluorophosphate is more preferred.

The total content of monofluorophosphate and difluorophosphate is usually 0.001% by mass or more, preferably 0.01% by mass or more, with respect to 100% by mass of the nonaqueous electrolytic solution, and 0.01% by mass or more. It is more preferably 1% by mass or more, particularly preferably 0.3% by mass or more, and most preferably 0.5% by mass or more. In addition, it is usually 10% by mass or less, preferably 8% by mass or less, more preferably 4% by mass or less, and 2
% by mass or less is particularly preferable, and 1.5% by mass or less is most preferable. If the total content of monofluorophosphate and difluorophosphate is within this range, the capacity after high-temperature storage is large when used as a non-aqueous electrolyte secondary battery, and battery swelling and metal elution are suppressed. Therefore, it is excellent in high-temperature life and safety, and can avoid an increase in the manufacturing cost of the non-aqueous electrolyte secondary battery.
Monofluorophosphates and difluorophosphates may be used alone, or two or more of them may be used in any combination and ratio.
In the present invention, the monofluorophosphate and difluorophosphate include those produced in the electrolyte and in the battery.

[1-4-12-2. borate]
The borate is not particularly limited as long as it has at least one boron atom in the molecule. However, those corresponding to oxalates are not borates but are included in oxalates described later. In the battery of the present invention, durability characteristics can be improved.
Counter cations in borates include lithium, sodium, potassium, magnesium, calcium, rubidium, cesium, barium and the like, with lithium being preferred.

As the borate, a lithium salt is preferable, and a borate-containing lithium salt can also be suitably used. _For example _{LiBF4 , LiBF3CF3 , LiBF3C2F5 , LiBF3C3
F7} , _{LiBF2 ( CF3 ) 2} , _LiBF2 ( _C2F5 ) ₂ , _LiBF2 ( _CF3SO2
) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ and the like. Among them, LiBF ₄ is more preferable because it has the effect of improving initial charge/discharge efficiency, high-temperature cycle characteristics, and the like.

Borates may be used singly, or two or more of them may be used in any combination and ratio.
The amount of borate (the total amount when two or more are used) is usually 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably 0% by mass. .3% by mass
above, particularly preferably 0.4% by mass or more, and usually 10.0% by mass or less,
Preferably 5.0 mass % or less, more preferably 3.0 mass % or less, still more preferably 2.0
% by mass or less, particularly preferably 1.0% by mass or less. Within this range, the side reaction of the negative electrode of the battery is suppressed and the resistance is less likely to increase.

[1-4-12-3. oxalate]
The oxalate is not particularly limited as long as it is a compound having at least one oxalic acid structure in the molecule. In the battery of the present invention, durability characteristics can be improved.
As the oxalate, a metal salt represented by the following formula (9) is preferable. This salt is a salt having an oxalato complex as an anion.

In formula (9), ^M1 is an element selected from the group consisting of Groups 1, 2 and aluminum (Al) in the periodic table, ^M2 is a transition metal, Groups 13, 14 and 15 of the periodic table R ⁹¹ is a group selected from the group consisting of halogen, an alkyl group having 1 to 11 carbon atoms and a halogen-substituted alkyl group having 1 to 11 carbon atoms,
a and b are positive integers, c is 0 or a positive integer, and d is an integer of 1-3.

M ¹ is lithium,
Sodium, potassium, magnesium, calcium are preferred, and lithium is particularly preferred.
Boron and phosphorus are particularly preferred as ^M2 from the viewpoint of electrochemical stability when used in non-aqueous electrolyte secondary batteries.

R ⁹¹ includes fluorine, chlorine, methyl group, trifluoromethyl group, ethyl group, pentafluoroethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, ter
A t-butyl group and the like can be mentioned, and fluorine and trifluoromethyl groups are preferred.
Examples of the metal salt represented by formula (9) include the following.
lithium oxalatoborate salts such as lithium difluorooxalatoborate and lithium bis(oxalato)borate;
lithium oxalatophosphate salts such as lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalato)phosphate, lithium tris(oxalato)phosphate;
Among these, lithium bis(oxalato)borate and lithium difluorobis(oxalato)phosphate are preferred, and lithium bis(oxalato)borate is more preferred.

One type of oxalate may be used alone, or two or more types may be used together in any combination and ratio.
The amount of oxalate (the total amount when two or more are used) is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and particularly preferably 0% by mass. .3
% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

[1-4-12-4. fluorosulfonate]
The fluorosulfonate is not particularly limited as long as it is a salt having at least one fluorosulfonic acid structure in the molecule. In the battery of the present invention, durability characteristics can be improved.
The counter cation in the fluorosulfonate is not particularly limited, and includes lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium and NR ¹³¹ R ¹³² R ¹³³ R ¹³⁴ (wherein R ¹³¹ to R ¹³⁴ are each independently a hydrogen atom or an organic group having 1 to 12 carbon atoms), and the like. Preferred counter cations are lithium, sodium and potassium, with lithium being particularly preferred.

Examples of the fluorosulfonate include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate, and cesium fluorosulfonate, with lithium fluorosulfonate being preferred. lithium bis (
An imide salt having a fluorosulfonic acid structure, such as fluorosulfonyl)imide, can also be used as the fluorosulfonate.

One type of fluorosulfonate may be used alone, or two or more types may be used together in any combination and ratio.
The content of the fluorosulfonate (the total amount when two or more are used) is usually 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably is 0.3% by mass or more, particularly preferably 0.4% by mass or more, and usually 10% by mass
or less, preferably 8% by mass or less, more preferably 5% by mass or less, still more preferably 2
% by mass or less, particularly preferably 1% by mass or less. Within this range, there are few side reactions in the battery and it is difficult to increase the resistance.

[2. Non-aqueous electrolyte secondary battery]
The non-aqueous electrolyte secondary battery of the present invention comprises a positive electrode having a positive electrode active material capable of absorbing and releasing metal ions, and a negative electrode having a negative electrode active material capable of absorbing and releasing metal ions. A secondary battery containing a non-aqueous electrolyte.

[2-1. Non-aqueous electrolyte]
As the non-aqueous electrolytic solution, the non-aqueous electrolytic solution described above is used. It should be noted that other non-aqueous electrolytic solutions may be mixed with the above-described non-aqueous electrolytic solution without departing from the scope of the present invention.

[2-2. negative electrode]
The negative electrode active material used for the negative electrode will be described below. The negative electrode active material is not particularly limited as long as it can electrochemically intercalate and deintercalate metal ions such as lithium ions. Specific examples include carbonaceous materials, alloy materials, and lithium-containing metal composite oxide materials. These may be used individually by 1 type, and may be used together, combining 2 or more types arbitrarily.

<Negative electrode active material>
Examples of negative electrode active materials include carbonaceous materials, alloy materials, and lithium-containing metal composite oxide materials.
Examples of carbonaceous materials include (1) natural graphite, (2) artificial graphite, (3) amorphous carbon, (4) carbon-coated graphite, (5) graphite-coated graphite, and (6) resin-coated graphite. .

(1) Examples of natural graphite include flake graphite, flake graphite, soil graphite, and/or graphite particles obtained by subjecting these graphites to processing such as spheroidization and densification. Among these, spherical or ellipsoidal graphite subjected to a spheroidizing treatment is particularly preferable from the viewpoint of particle filling properties and charge/discharge rate characteristics.

(2) Artificial graphite includes coal tar pitch, coal-based heavy oil, atmospheric residual oil, petroleum-based heavy oil, aromatic hydrocarbons, nitrogen-containing cyclic compounds, sulfur-containing cyclic compounds, polyphenylene, polyvinyl chloride, Organic compounds such as polyvinyl alcohol, polyacrylonitrile, polyvinyl butyral, natural polymers, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, imide resin, etc.
Graphitized at a temperature in the range of 00° C. or higher and usually 3200° C. or lower, and optionally pulverized and/or classified, and produced. At this time, a silicon-containing compound, a boron-containing compound, or the like can also be used as a graphitization catalyst. In addition, artificial graphite obtained by graphitizing mesocarbon microbeads separated in the heat treatment process of pitch may be used. Artificial graphite in the form of granulated particles composed of primary particles may also be used. For example, by mixing mesocarbon microbeads or graphitizable carbonaceous material powder such as coke with a graphitizable binder such as tar or pitch and a graphitization catalyst, graphitizing, and pulverizing as necessary. Graphite particles obtained by aggregating or bonding a plurality of flattened particles so that the orientation planes are non-parallel can be mentioned.

(3) As amorphous carbon, graphitizable carbon precursors such as tar and pitch are used as raw materials,
Examples include amorphous carbon particles that have been heat-treated at least once in a temperature range that does not graphitize (range of 400 to 2200° C.) and amorphous carbon particles that have been heat-treated using a non-graphitizable carbon precursor such as resin as a raw material. be done.

(4) Carbon-coated graphite is obtained by mixing natural graphite and/or artificial graphite with a carbon precursor, which is an organic compound such as tar, pitch, or resin, and heat-treating the mixture at a temperature of 400 to 2,300° C. one or more times. Examples thereof include carbon-graphite composites in which natural graphite and/or artificial graphite are used as core graphite and amorphous carbon covers the core graphite. The composite form may be one in which the entire surface or a part of the surface is coated, or a plurality of primary particles are composited using the carbon originating from the carbon precursor as a binder. In addition, natural graphite and/or artificial graphite are reacted with hydrocarbon gases such as benzene, toluene, methane, propane, and aromatic volatiles at high temperatures to deposit carbon on the graphite surface (CVD).
A carbon-graphite composite can also be obtained by

(5) Graphite-coated graphite is prepared by mixing natural graphite and/or artificial graphite with a carbon precursor of an easily graphitizable organic compound such as tar, pitch or resin, and heating the mixture once in the range of about 2400 to 3200°C. Natural graphite and/or artificial graphite obtained by the above heat treatment is used as the core graphite, and graphite-coated graphite in which the whole or a part of the surface of the core graphite is coated with the graphite is exemplified.

(6) As the resin-coated graphite, a mixture of natural graphite and/or artificial graphite and resin etc., 400
Resin-coated graphite in which natural graphite and/or artificial graphite obtained by drying at a temperature of less than °C is used as the core graphite, and the core graphite is coated with a resin or the like can be mentioned.
The carbonaceous materials (1) to (6) may be used singly, or two or more of them may be used in any combination and ratio.

As the alloy-based material used as the negative electrode active material, if it is possible to absorb and release lithium, elemental lithium, elemental metals and alloys forming lithium alloys, or oxides, carbides, nitrides, silicides, and sulfides thereof or a compound such as a phosphide, and is not particularly limited. The elemental metals and alloys forming the lithium alloy are preferably materials containing group 13 and group 14 metal/metalloid elements (that is, excluding carbon), more preferably aluminum, silicon and tin elemental metals and alloys. It is an alloy or compound containing these atoms. These may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

<Physical properties of carbonaceous material>
When a carbonaceous material is used as the negative electrode active material, it preferably has the following physical properties.

(X-ray parameters)
The d value (interlayer distance) of the lattice plane (002 plane) obtained by X-ray diffraction by the Gakushin method of the carbonaceous material is usually 0.335 nm or more, and is usually 0.360 nm or less, and is 0.350 n
m or less is preferable, and 0.345 nm or less is more preferable. The crystallite size (Lc) of the carbonaceous material determined by X-ray diffraction according to the Gakushin method is preferably 1.0 nm or more, more preferably 1.5 nm or more.

(Volume-based average particle size)
The volume-based average particle diameter of the carbonaceous material is the volume-based average particle diameter (median diameter) determined by a laser diffraction/scattering method, and is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and 7 μm. The above are particularly preferred. In addition, it is usually 100 μm or less, and 50 μm or less.
μm or less is preferable, 40 μm or less is more preferable, and 30 μm or less is even more preferable.
5 μm or less is particularly preferred.

If the volume-based average particle size is below the above range, the irreversible capacity increases, which may lead to loss of initial battery capacity. On the other hand, when the above range is exceeded, the coated surface tends to be non-uniform when the electrode is produced by coating, which may not be desirable in terms of the battery production process.

(BET specific surface area)
The BET specific surface area of the carbonaceous material is the value of the specific surface area measured using the BET method, and is usually 0.1 m ² ·g ⁻¹ or more, preferably 0.7 m ² ·g ⁻¹ or more. ^{0m2.g -
1} or more is more preferable, and 1.5 m ² ·g ⁻¹ or more is particularly preferable. In addition, usually 100 m ²
·g ⁻¹ or less, preferably 25 m ² ·g ⁻¹ or less, more preferably 15 m ² ·g ⁻¹ or less, particularly preferably 10 m ² ·g ⁻¹ or less.

If the value of the BET specific surface area is below this range, the acceptability of lithium tends to deteriorate during charging when used as a negative electrode material, lithium tends to deposit on the electrode surface, and stability may decrease. On the other hand, if it exceeds this range, the reactivity with the non-aqueous electrolytic solution increases when used as a negative electrode material, gas generation tends to increase, and it may be difficult to obtain a preferable battery.

<Structure and manufacturing method of negative electrode>
Any known method can be used to manufacture the electrode as long as it does not significantly impair the effects of the present invention. For example, a negative electrode active material may be formed by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, etc., to form a slurry, applying the slurry to a current collector, drying the slurry, and pressing the slurry. can be done.
In addition, when using an alloy-based material, by means of vapor deposition, sputtering, plating, etc.,
A method of forming a thin film layer (negative electrode active material layer) containing the above-described negative electrode active material is also used.

(electrode density)
The electrode structure when the negative electrode active material is formed into an electrode is not particularly limited, but the density of the negative electrode active material present on the current collector is preferably 1 g cm ⁻³ or more, and 1.2 g cm ⁻³ or more. is more preferable, and 1.3 g·cm ⁻³ or more is particularly preferable. Also, it is preferably 2.2 g·cm ⁻³ or less, more preferably 2.1 g·cm ⁻³ or less, still more preferably 2.0 g·cm ⁻³ or less, and particularly preferably 1.9 g·cm ⁻³ or less.

When the density of the negative electrode active material present on the current collector exceeds the above range, the negative electrode active material particles are destroyed, the initial irreversible capacity increases, and the non-aqueous A deterioration in high-current-density charge-discharge characteristics may be caused due to a decrease in permeability of the electrolytic solution. On the other hand, below the above range, the conductivity between the negative electrode active materials may decrease, the battery resistance may increase, and the capacity per unit volume may decrease.

[2-3. positive electrode]
<Positive electrode active material>
The positive electrode active material (lithium transition metal compound) used for the positive electrode is described below.
<Lithium transition metal compound>
A lithium transition metal-based compound is a compound having a structure capable of desorbing and inserting Li ions, and the lithium transition metal-based compound used in the present invention is represented by the following space group formula. It is. Moreover, those belonging to a layered structure that enables two-dimensional diffusion of lithium ions are preferable. A more detailed description of the layered structure will now be provided. Typical crystal systems having a layered structure include α-NaFeO such as LiCoO ₂ and LiNiO ₂ .
There are those belonging to type ₂ , which are hexagonal and, due to their symmetry, the space group

(hereinafter sometimes referred to as “layered R(−3)m structure”).
However, the layered LiMeO ₂ is not limited to the layered R(−3)m structure. In addition, _LiMnO2 , which _is called so-called _layered Mn, is an orthorhombic system _and is a layered compound with space group Pm2m _.
/3 ]O ₂ , which has a monoclinic space group C2/m structure, but also the Li layer and the [L
i _1/3 Mn _2/3 ] layer and an oxygen layer.

(lithium transition metal compound)
The lithium transition metal compound according to the present invention is a lithium transition metal compound represented by the following compositional formula (I).
Li _1+x M ³ O ₂ (I)
In formula (I), x is -0.1 or more and 0.5 or less. Above all, the lower limit of x is -0.0
It is preferably 4 or more, more preferably -0.03 or more, particularly preferably -0.02 or more, and most preferably -0.01 or more. In addition, the upper limit of x is more preferably 0.2 or less, particularly preferably 0.1 or less,
Most preferably, it is 0.05 or less. If x is within the above range, it is preferable because sufficient charge/discharge capacity appears.

Furthermore, in formula (I), ^M3 is a plurality of elements containing at least Ni and Co, Ni
/ ^M3 molar ratio is 0.55 or more and 1.0 or less. More preferably, ^M3 is at least N
i, Mn and Co are included, and the Ni/(Ni+Mn+Co) molar ratio is preferably 0.65 or more. The lower limit of the Ni/(Ni+Mn+Co) molar ratio is more preferably 0.75 or more, most preferably 0.85 or more. The upper limit of the Ni/(Ni+Mn+Co) molar ratio is usually 0.98 or less, more preferably 0.95 or less, even more preferably 0.93 or less, and most preferably 0.90 or less.

If the Ni/(Ni+Mn+Co) molar ratio is within the above range, the combination with the compound represented by the formula (II) contained in the non-aqueous electrolytic solution has the effect of suppressing gas generation and the effect of increasing the retention rate of the capacity after storage. It is preferable because it is sufficiently easy to express.
Furthermore, the Mn/(Ni+Mn+Co) molar ratio is not particularly limited, but is usually 0 or more, 0
. 32 or less. Preferably the Mn/(Ni+Mn+Co) molar ratio is greater than 0,
32 or less.

The lower limit of the Mn/(Ni+Mn+Co) molar ratio is preferably 0.05 or more, more preferably 0.08 or more, still more preferably 0.10 or more, particularly preferably 0.12 or more, and 0.05 or more.
14 or more is most preferred. In addition, the upper limit of the Mn / (Ni + Mn + Co) molar ratio is 0.2
8 or less is preferable, 0.26 or less is more preferable, 0.25 or less is still more preferable, and 0.25 or less is more preferable.
24 or less is particularly preferred, and 0.23 or less is most preferred.

If the Mn/(Ni+Mn+Co) molar ratio is within the above range, Mn that does not participate in charging and discharging
is sufficiently small, and the battery has a high capacity.
Furthermore, the lower limit of the Co / (Ni + Mn + Co) molar ratio is preferably 0.05 or more, and 0
. 08 or more is more preferable, 0.10 or more is particularly preferable, and 0.15 or more is most preferable. The upper limit of the Co/(Ni+Mn+Co) molar ratio is not particularly limited, but 0.3
3 or less is preferable, 0.30 or less is more preferable, 0.28 or less is still more preferable, and 0.28 or less is more preferable.
26 or less is particularly preferred, and 0.24 or less is most preferred.

If the Co/(Ni+Mn+Co) molar ratio is within the above range, the charge/discharge capacity is increased, which is preferable.
In the above composition formula (I), the atomic ratio of the oxygen content is described as 2 for the sake of convenience, but there may be some non-stoichiometry. Also, x in the above formula (I) is the charged composition at the stage of manufacturing the lithium transition metal compound. Normally, after assembling the batteries on the market,
aging. Therefore, the amount of Li in the positive electrode may be depleted during charging and discharging.

Also, a different element may be introduced into the lithium transition metal-based compound. As a foreign element, B
, Na, Mg, Al, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr,
Nb, Ru, Rh, Pd, Ag, In, Sb, Te, Ba, Ta, Mo, W, Re, Os
, Ir, Pt, Au, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy,
Ho, Er, Tm, Yb, Lu, Bi, N, F, S, Cl, Br, I, As, Ge, P,
It is selected from one or more of Pb, Sb, Si and Sn. Among them, Fe, Cu
, W, Mo, Nb, V, Ta, Mg, Al, Ti, Zr, Zn, Ca, Be, B, Bi,
At least one element selected from the group consisting of Li, Na and K is preferred.

These different elements may be incorporated into the crystal structure of the lithium transition metal compound, or may not be incorporated into the crystal structure of the lithium transition metal compound, and may be present as single or compound elements on the particle surfaces or grain boundaries. It may be unevenly distributed as
(Positive electrode active material containing lithium transition metal compound, or physical properties of lithium transition metal compound)

(1) Sulfate The positive electrode active material may contain sulfate. The content of sulfate that can be contained in the positive electrode active material is
Although not particularly limited, a concentration of 15 μmol/g or more is preferable because the effect of suppressing gas generation by the silyl ester compound and the effect of increasing the retention rate of capacity after storage are sufficiently exhibited.
Further, it is more preferably 20 μmol/g or more, further preferably 25 μmol/g or more, particularly preferably 32 μmol/g or more, and 35 μmol/g.
/g or more is most preferable. In addition, the upper limit is preferably 100 μmol/g or less, and 80 μmol/g, because gas generation due to side reactions increases.
is more preferably 60 μmol/g or less, and 5
0 μmol/g or less is particularly preferable, and 30 μmol/g or less is most preferable.
In addition, the sulfate contained in the positive electrode active material can be measured, for example, by water extraction ion chromatography.
(2) Ni average valence The lithium transition metal compound contained in the positive electrode active material has no particular limitation on the Ni average valence in an uncharged state, but an Ni ratio of 2.1 or more can increase the Ni ratio. , which is preferable because the battery can have a high capacity. Moreover, it is more preferably 2.3 or more, and 2.5
It is more preferably 2.55 or more, particularly preferably 2.55 or more, and most preferably 2.6 or more. Further, the upper limit value is preferably 3 or less, more preferably 2.9 or less, particularly preferably 2.8 or less, and 2.7 because the structural stability of the active material is lowered. Most preferably:

Here, the Ni valence in the present invention will be described in detail.
First, when the composition formula of the lithium transition metal compound is rewritten as the following composition formula (I′), M
' is an element composed of at least Li, Ni and Co.
_LiM'O2 (I')
In the above composition formula (I'), the atomic ratio of the oxygen content is described as 2 for convenience.
There may be some non-stoichiometry. When non-stoichiometric, the atomic ratio of oxygen is usually in the range of 2±0.2, preferably 2±0.15, more preferably 2±0.12, still more preferably 2±0.10. is particularly preferably in the range of 2±0.05.

Furthermore, it is particularly preferable that the lithium transition metal-based compound has an atomic configuration at the M' site in the composition formula (I') represented by the following formula (II).
M′=Li _z/(2+z) {(Ni _(1+y)/2 Mn _(1−y)/2 ) _1−x Co _x }
_2/(2+z) ...(II')
Here, the chemical meaning of the Li composition (z and x) in the lithium-nickel-manganese-cobalt-based composite oxide, which is the preferred composition of the lithium-transition metal-based compound, will be described in more detail below.

As described above, the layered structure is not necessarily limited to the R(-3)m structure, but the R(-
3) It is preferable from the standpoint of electrochemical performance that it can be attributed to the m-structure.
To obtain x, y, and z in the composition formula of the lithium-transition metal-based compound, each transition metal and Li
is analyzed with an inductively coupled plasma atomic emission spectrometer (ICP-AES), and the surface impurity Li is analyzed by water extraction ion chromatography, and the Li / Ni / Mn / Co of the lithium transition metal compound Calculated by finding the ratio.

From a structural point of view, Li associated with z is considered to be substituted at the same transition metal site. Here, Li associated with z causes the average valence of Ni to be greater than 2 (trivalent Ni is produced) due to the principle of charge neutrality. Since z increases the Ni average valence, it serves as an index of the Ni valence (the ratio of Ni(III)).
When the Ni valence (m) accompanying changes in z and z' is calculated from the above composition formula, on the premise that the Co valence is trivalent and the Mn valence is tetravalent,

becomes. This calculation result means that the Ni valence is not determined only by z but is a function of x and y. If z = 0 and y = 0, the Ni valence is 2 regardless of the value of x.
value remains. When z becomes a negative value, it means that the amount of Li contained in the active material is less than the stoichiometric amount. have a nature. On the other hand, even with the same z value, Ni-rich (larger y-value) and/or Co-rich (larger x-value) compositions have higher Ni valences. Rate characteristics and output characteristics are improved, but on the other hand, the result is that the capacity tends to decrease. From this, it can be said that it is more preferable to define the upper and lower limits of the z value as a function of x and y.
In addition, when the x value is in the range of 0 ≤ x ≤ 0.1 and the amount of Co is small, in addition to reducing the cost, the non-aqueous electrolyte secondary battery designed to be charged at a high charging potential When used as a charge-discharge capacity, cycle characteristics, and safety are improved.

(3) pH
The pH of the aqueous solution of the lithium transition metal-based compound is not particularly limited, but when it is 11 or more, the effect of suppressing gas generation due to the combination with the monofluorophosphate and/or difluorophosphate contained in the electrolyte is sufficient. It is preferable because it is likely to be expressed in Further, it is more preferably 11.2 or more, more preferably 11.4 μmol/g or more, and 11
. 6 or more is particularly preferred, and 11.8 or more is most preferred. In addition, the upper limit is preferably 13 or less because the generation of gas due to side reactions is reduced.
It is more preferably 12.7 or less, particularly preferably 12.4 or less, and 12
Most preferably:
In addition, as a method for measuring the pH of the lithium transition metal compound, 50 g of desalted water is weighed in a beaker, 5 g of the sample is added while stirring, and 10 minutes have elapsed after the addition while monitoring the liquid temperature and pH value. Values obtained by measuring the pH value and liquid temperature later are used.

(4) Carbonate The positive electrode active material may contain carbonate. The content of carbonate that can be contained in the positive electrode active material is
Although not particularly limited, it is preferably 10 μmol/g or more because the effect of suppressing gas generation by the combination with the monofluorophosphate and/or difluorophosphate contained in the electrolytic solution can be sufficiently exhibited. Further, it is more preferably 20 μmol / g or more,
It is more preferably 40 μmol/g or more, particularly preferably 60 μmol/g or more, and most preferably 80 μmol/g or more. In addition, the upper limit is preferably 100 μmol/g or less, more preferably 98 μmol/g or less, particularly preferably 96 μmol/g or less, and particularly preferably 94 μmol/g, in order to reduce gas generation due to side reactions. g or less is most preferred.
In addition, as a method for measuring the carbonate contained in the lithium transition metal compound, for example, it can be measured by a water extraction ion chromatography method.

(5) Tap density The lithium transition metal-based compound that constitutes the positive electrode active material is usually powder, and its tap density is not particularly limited, but it should be 1.8 g/cm ³ or more when the battery is charged. It is preferable because of its large discharge capacity. Moreover, it is more preferably 2 g/cm ³ or more, and 2.1 g/cm 3 or more.
It is more preferably 2.2 g/cm ³ or more, particularly preferably 2.2 g/cm ³ or more, and most preferably 2.3 g/cm ³ or more. Moreover, the upper limit is preferably 4.0 g/cm ³ or less, more preferably 3.8 g/cm ³ or less, and 3.6 g/cm ³ or less because the output characteristics are sufficient. is particularly preferred, 3.4 g/
cm ³ or less is most preferred.

A high-density positive electrode can be formed by using a lithium-transition metal-based compound with a high tap density. When the tap density of the lithium transition metal-based compound is within the above range, the amount of the dispersion medium required for forming the positive electrode is appropriate, and the amount of the conductive material and the binder is also appropriate. The effect on the battery capacity is reduced without restricting the filling rate of the metal-based compound.

After the sample was dropped into a 10 mL measuring cylinder to fill the volume, tapping was performed 200 times, and the density was calculated from the volume at that time and the mass of the sample. The tap density calculated by the measurement,
It is defined as the tap density of the lithium transition metal compound in the present invention.
In addition, the tap density of the lithium transition metal compound is measured by passing the sample through a sieve with an opening of 300 μm, dropping the sample into a tapping cell of 20 cm ³ to fill the cell volume, and then using a powder density measuring instrument (for example, Stroke length 10mm using Seishin Enterprise Co., Ltd.
may be tapped 200 times, and the density may be calculated from the volume and mass of the sample at that time.
In addition, simply drop the sample into a 10 mL graduated cylinder and fill the volume with 200
The density may be calculated from the volume and the mass of the sample after tapping twice.

(6) Surface Coating A substance having a composition different from that of the substance constituting the main lithium transition metal compound (hereinafter referred to as “surface adhering substance”) attached to the surface of the above lithium transition metal compound. can also be used. Examples of surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, oxides such as bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, Examples include sulfates such as calcium sulfate and aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate, and carbon.

These surface-adhering substances are, for example, dissolved or suspended in a solvent and impregnated with a lithium-transition metal-based compound, followed by drying; It can be attached to the surface of the lithium transition metal compound by impregnating and adding it to the surface of the lithium transition metal compound and then reacting it by heating or the like, adding it to the lithium transition metal compound precursor and calcining it at the same time. When carbon is deposited, a method of mechanically depositing carbonaceous matter in the form of activated carbon or the like later can also be used.

The mass of the surface-attached substance adhering to the surface of the lithium-transition metal-based compound is preferably 0.1 ppm or more, more preferably 1 ppm or more, and even more preferably 10 ppm or more, relative to the mass of the lithium-transition metal-based compound. . Moreover, it is preferably 20% or less, and 10%
The following is more preferable, and 5% or less is even more preferable.
The surface-adhering substance can suppress the oxidation reaction of the non-aqueous electrolytic solution on the surface of the lithium transition metal-based compound, thereby improving the battery life. In addition, when the amount of adhesion is within the above range, the effect can be sufficiently exhibited, and the resistance is less likely to increase without inhibiting the entry and exit of lithium ions.

(7) Shape The shape of the lithium-transition metal-based compound is conventionally used, such as massive, polyhedral, spherical,
Elliptical spherical shape, plate shape, acicular shape, columnar shape, etc. are used. Further, primary particles may aggregate to form secondary particles, and the secondary particles may have a spherical or elliptical shape.

(8) Median diameter d50
The median diameter d50 of the lithium transition metal-based compound (the secondary particle diameter when the primary particles are aggregated to form secondary particles) can be measured using a laser diffraction/scattering particle size distribution analyzer. can.
The median diameter d50 is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1 μm or more, particularly preferably 3 μm or more, and more preferably 30 μm.
20 μm or less, more preferably 16 μm or less, and particularly preferably 15 μm or less. When the median diameter d50 is within the above range, it is easy to obtain a high bulk density product, and furthermore, diffusion of lithium in the particles does not take much time, so battery characteristics are less likely to deteriorate. In addition, streaks and the like are less likely to occur when the positive electrode of a battery is prepared, that is, when an active material, a conductive material, a binder, and the like are slurried with a solvent and applied in the form of a thin film.

By mixing two or more kinds of lithium transition metal compounds having different median diameters d50 at an arbitrary ratio, the filling property during fabrication of the positive electrode can be further improved.
The median diameter d50 of the lithium transition metal-based compound is measured using a 0.1% by mass aqueous solution of sodium hexametaphosphate as a dispersion medium and using a particle size distribution meter (for example, LA-92 manufactured by Horiba Ltd.).
0), measurement is performed by setting the measurement refractive index to 1.24 after ultrasonic dispersion for 5 minutes in a dispersion liquid of a lithium transition metal compound.

(9) Average primary particle size When the primary particles are aggregated to form secondary particles, the average primary particle size of the lithium-transition metal-based compound is preferably 0.01 μm or more, and more preferably 0.05 μm or more. preferably 0
. More preferably 08 μm or more, particularly preferably 0.1 μm or more, and preferably 3 μm
m or less, preferably 2 μm or less, even more preferably 1 μm or less, and particularly preferably 0.6 μm or less. Within the above range, it becomes easier to form spherical secondary particles, the powder filling property becomes moderate, and a sufficient specific surface area can be secured, so deterioration of battery performance such as output characteristics can be suppressed. .

The average primary particle size of the lithium transition metal-based compound is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10,000 times, the maximum value of the intercept of the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for arbitrary 50 primary particles, and the average value is obtained. be done.

(10) BET specific surface area The BET specific surface area of the lithium transition metal-based compound is preferably 0.2 m ² · g ^-1 or more, and 0.3 m ² · g, as measured by the BET method. ⁻¹ or more, more preferably 0.4 m ² ·g ⁻¹ or more, preferably 4.0 m ² ·g ⁻¹ or less, more preferably 2.5 m ² ·g ⁻¹ or less, and 1 0.5 m ² ·g ⁻¹ or less is more preferable. When the value of the BET specific surface area is within the above range, deterioration of battery performance can be easily prevented. moreover,
Sufficient tap density can be ensured, and coatability at the time of positive electrode formation is improved.

The BET specific surface area of the lithium transition metal compound is measured using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken). Specifically, the sample was heated at 150°C for 3
After pre-drying for 0 minutes, using a nitrogen-helium mixed gas accurately adjusted so that the value of the relative pressure of nitrogen to the atmospheric pressure is 0.3, the nitrogen adsorption BET one-point method by the gas flow method. do. The specific surface area determined by the measurement is defined as the BET specific surface area of the lithium transition metal compound in the present invention.

(Method for producing positive electrode active material containing lithium transition metal compound)
The method for producing a positive electrode active material containing a lithium transition metal-based compound is not particularly limited as long as it does not exceed the gist of the present invention. Used.
In particular, various methods are conceivable for producing a spherical or elliptical positive electrode active material. The substance is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to prepare and recover a _spherical precursor _.
A method of adding a Li source such as LiNO ₃ and sintering at a high temperature to obtain a positive electrode active material is exemplified.

As an example of another method, transition metal raw materials such as transition metal nitrates, sulfates, hydroxides and oxides and, if necessary, raw materials of other elements are dissolved or pulverized and dispersed in a solvent such as water. do,
It is dried and molded with a spray dryer or the like to obtain a spherical or ellipsoidal precursor.
A method of obtaining a positive electrode active material by adding a Li source such as iOH, Li ₂ CO ₃ or LiNO ₃ and baking at a high temperature can be mentioned.

As yet another example of a method, transition metal source materials such as transition metal nitrates, sulfates, hydroxides and oxides, Li sources such as LiOH, Li ₂ CO ₃ and LiNO ₃ and optionally other elements A method of dissolving or pulverizing and dispersing the starting material in a solvent such as water, drying and molding it with a spray dryer or the like to obtain a spherical or ellipsoidal precursor, and firing this at a high temperature to obtain a positive electrode active material. is mentioned.

In the selection of the transition metal source material, the content of sulfate and carbonate in the positive electrode active material described above can be adjusted by adjusting the amount of sulfate and carbonate used, by adjusting the baking temperature, by the presence or absence of washing, and the like. The content can be any desired value.
The lithium-transition metal-based compound used for the positive electrode active material may be used alone or in combination of two or more. It may also be blended with sulfides, phosphate compounds, other lithium-transition metal composite oxides, and the like. As sulfides, _TiS2 and MoS
₂ and compounds having a two-dimensional layered structure such as Me _x Mo ₆ S ₈ (Me is Pb, Ag,
various transition metals including Cu), and the like. Phosphate compounds include those belonging to the olivine structure, generally represented by LiMePO ₄ (Me is at least one transition metal), specifically LiFePO ₄ , LiCoPO ₄ , L
Examples include iNiPO ₄ and LiMnPO ₄ . As a lithium transition metal composite oxide,
Examples include those belonging to a spinel structure that allows three-dimensional diffusion and a layered structure that allows two-dimensional diffusion of lithium ions. Those having a spinel structure are generally LiMe ₂ O ₄
(Me is at least one transition metal), specifically LiMn ₂ O ₄ , LiC
oMnO ₄ , LiNi _0.5 Mn _1.5 O ₄ , LiCoVO ₄ and the like. Those having a layered structure are specifically LiCoO ₂ , LiNiO ₂ , LiNi _1-x Co _x O ₂ ,
_{LiNi1 - xyCoxMnyO2 , LiNi0.5Mn0.5O2 , Li1.2Cr _
0.4Mn0.4O2 , Li1.2Cr0.4Ti0.4O2 , LiMnO2 and} the _{like .}

<Structure and manufacturing method of positive electrode for non-aqueous electrolyte secondary battery>
The positive electrode for a non-aqueous electrolyte secondary battery is formed by forming a layer of a positive electrode active material containing a positive electrode active material containing the above lithium transition metal compound and a binder on a current collector.
The positive electrode active material layer is usually formed by dry-mixing a positive electrode active material containing a lithium transition metal-based compound, a binder, and optionally a conductive material, a thickener, and the like into a sheet. to the positive electrode current collector, or by dissolving or dispersing these materials in a liquid medium to form a slurry, coating the positive electrode current collector, and drying.

As the material of the positive electrode current collector, metal materials such as aluminum, stainless steel, nickel plating, titanium and tantalum, and carbon materials such as carbon cloth and carbon paper are usually used. As for the shape, metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, foam metal, etc., for metal materials; carbon plate, carbon thin film, carbon cylinder, etc. for carbon materials. is mentioned.

Incidentally, the thin film may be appropriately formed in a mesh shape.
The binder used for manufacturing the layer of the positive electrode active material is not particularly limited, and in the case of the coating method, any material that is stable with respect to the liquid medium used for manufacturing the electrode may be used. , resin polymers such as polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, nitrocellulose, SBR (styrene,
butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluororubber, isoprene rubber, butadiene rubber, rubber-like polymers such as ethylene-propylene rubber, styrene-butadiene-styrene block copolymers and hydrogenated products thereof, EPDM (ethylene propylene-diene terpolymer), styrene-ethylene-butadiene-ethylene copolymer, thermoplastic elastomeric polymer such as styrene-ethylene-butadiene-ethylene copolymer, styrene-isoprene-styrene block copolymer and hydrogenated products thereof, syndiotactic-1, Soft resinous polymers such as 2-polybutadiene, polyvinyl acetate, ethylene/vinyl acetate copolymer, propylene/α-olefin copolymer,
polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride,
Examples thereof include fluorine-based polymers such as polytetrafluoroethylene/ethylene copolymers, and polymer compositions having ion conductivity for alkali metal ions (especially lithium ions).

In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more and 80% by mass or less. If the proportion of the binder is too low, the lithium-transition metal-based compound cannot be sufficiently retained, resulting in insufficient mechanical strength of the positive electrode, which may deteriorate battery performance such as cycle characteristics. may lead to a decrease in battery capacity and conductivity.

The positive electrode active material layer usually contains a conductive material in order to increase conductivity.
Although there is no particular limitation on the type thereof, specific examples include metal materials such as copper and nickel, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke. and the like.
In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

The ratio of the conductive material in the positive electrode active material layer is usually 0.01% by mass or more and 50% by mass or less.
If the proportion of the conductive material is too low, the conductivity may become insufficient, and conversely, if it is too high, the battery capacity may decrease.
As the liquid medium for forming the slurry, a positive electrode active material containing a lithium transition metal compound as a positive electrode material, a binder, and optionally a conductive material and a thickener are dissolved or dispersed. As long as the solvent is capable of Examples of aqueous solvents include water and alcohols, and examples of organic solvents include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N , N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran (THF), toluene, acetone, dimethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane, etc. be able to. In particular, when using an aqueous solvent, a dispersant is added together with a thickener, and the mixture is slurried using a latex such as SBR.

In addition, these solvents may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
The content ratio of the lithium transition metal compound as the positive electrode material in the positive electrode active material layer is usually 10
It is more than mass % and below 99.9 mass %. If the proportion of the lithium transition metal-based compound in the positive electrode active material layer is too high, the strength of the positive electrode tends to be insufficient, and if it is too low, the capacity may be insufficient.

Moreover, the thickness of the positive electrode active material layer is usually about 10 to 200 μm.
The plate density of the positive electrode after pressing is not particularly limited, but it is preferably 3.0 g/cm ³ or more because the battery can have a high capacity. Further, it is more preferably 3.2 g/cm ³ or more, particularly preferably 3.4 g/cm ³ or more, and 3.6 g/cm 3 or more.
cm ³ or more is most preferred. In addition, the upper limit is preferably 4.2 ^g /cm ³ or less, more preferably 4.1 g/cm 3 or less, and 4.0 g/cm ³ or less, since deterioration of input/output characteristics is unlikely to occur. is particularly preferred, 3.9 g/cm
³ or less is most preferred.
The positive electrode active material layer obtained by coating and drying is preferably densified by a roller press or the like in order to increase the filling density of the positive electrode active material.

[2-4. Separator]
A separator is usually interposed between the positive electrode and the negative electrode in order to prevent a short circuit. In this case, the separator is usually impregnated with the non-aqueous electrolytic solution.
The material and shape of the separator are not particularly limited, and known materials can be arbitrarily adopted as long as they do not significantly impair the effects of the present invention. Among them, resins, glass fibers, inorganic substances, etc., which are made of materials that are stable against non-aqueous electrolytes, are used, and it is preferable to use porous sheets or non-woven fabrics with excellent liquid retention properties.

Examples of materials for the resin or glass fiber separator include polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, and glass filters. Among them, glass filters and polyolefins are preferred, and polyolefins are more preferred. These materials are 1
A species may be used alone, or two or more species may be used in any combination and ratio.

Although the thickness of the separator is arbitrary, it is usually 1 μm or more, preferably 5 μm or more, and 1 μm or more.
0 μm or more is more preferable. In addition, it is usually 50 μm or less, preferably 40 μm or less,
30 μm or less is more preferable.
If the separator is thinner than the above range, the insulating properties and mechanical strength may deteriorate.
On the other hand, if the thickness is more than the above range, not only the battery performance such as rate characteristics may deteriorate, but also the energy density of the non-aqueous electrolyte secondary battery as a whole may deteriorate.

Furthermore, when a porous material such as a porous sheet or non-woven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, and more preferably 45% or more. Moreover, it is usually 90% or less, preferably 85% or less, and more preferably 75% or less.
If the porosity is too smaller than the above range, the film resistance tends to increase and the rate characteristics tend to deteriorate. On the other hand, when the thickness is too much larger than the above range, the mechanical strength of the separator tends to decrease and the insulation tends to decrease.

In addition, although the average pore size of the separator is also arbitrary, it is usually 0.5 μm or less, and 0.2 μm
The following are preferred. Moreover, it is usually 0.05 μm or more. If the average pore diameter exceeds the above range, short circuits tend to occur. On the other hand, below the above range, the film resistance may increase and the rate characteristics may deteriorate.
On the other hand, as inorganic materials, for example, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and those in the form of particles or fibers are used. Used.

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

The characteristics of the separator in the non-electrolyte secondary battery can be grasped by the Gurley value. The Gurley value indicates how difficult it is for air to pass through in the thickness direction of the film, and is expressed in seconds required for 100 ml of air to pass through the film. It means that it is difficult to pass through. That is, a smaller numerical value means better continuity in the thickness direction of the film, and a greater numerical value means poor continuity in the thickness direction of the film. Continuity is the degree of connection of pores in the thickness direction of the film. If the Gurley value of the separator of the present invention is low, it can be used for various purposes. For example, when it is used as a separator for a non-aqueous electrolyte secondary battery, a low Gurley value means easy movement of lithium ions, which is preferable because it is excellent in battery performance. The Gurley value of the separator is optional, but preferably 10 to 1000 seconds/100 ml,
More preferably 15 to 800 seconds/100 ml, still more preferably 20 to 500 seconds/1
00 ml. If the Gurley value is 1000 seconds/100 ml or less, the electrical resistance is substantially low, which is preferable as a separator.

[2-5. battery design]
<Electrode group>
The electrode group has a laminate structure in which the positive electrode plate and the negative electrode plate are interposed with the separator,
and a structure in which the positive electrode plate and the negative electrode plate are spirally wound with the separator interposed therebetween.

The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy) is usually 40
% or more, preferably 50% or more. Moreover, it is usually 90% or less, preferably 80% or less.
If the electrode group occupancy is below the above range, the battery capacity will be small. If the above range is exceeded, the void space is small, and the internal pressure rises due to the swelling of the members due to the high temperature of the battery and the increase in the vapor pressure of the liquid component of the electrolyte, and the repeated charging and discharging performance as a battery. In addition, the gas release valve that releases the internal pressure to the outside may operate.

<Exterior case>
The material of the exterior case is not particularly limited as long as it is stable with respect to the non-aqueous electrolytic solution used. Specifically, nickel-plated steel sheets, metals such as stainless steel, aluminum or aluminum alloys, and magnesium alloys, laminated films of resin and aluminum foil, and the like are used. From the viewpoint of weight reduction, aluminum or aluminum alloy metals and laminated films are preferably used.

In the exterior case using metals, the metals are welded together by laser welding, resistance welding, or ultrasonic welding to form a sealing and airtight structure, or the above metals are used through a resin gasket to form a crimped structure. things are mentioned.
Examples of exterior cases using the laminate film include those having a sealing and airtight structure by heat-sealing the resin layers to each other. A resin different from the resin used for the laminate film may be interposed between the resin layers in order to improve the sealing property.
In particular, when the resin layer is heat-sealed through the current collector terminal to form a closed structure, the metal and the resin are joined together. A resin is preferably used.

<Protection element>
As a protective element, PTC (Posit
ive Temperature Coefficient), a thermal fuse, a thermistor, a valve (current cut-off valve) that cuts off the current flowing in the circuit due to a rapid increase in the internal pressure or temperature of the battery during abnormal heat generation, or the like can be used. It is preferable to select the protective element under the condition that it does not operate under normal high-current use, and it is more preferable to design such that abnormal heat generation and thermal runaway do not occur even without the protective element.

<Exterior body>
The non-aqueous electrolyte secondary battery of the present invention is generally constructed by housing the non-aqueous electrolyte, the negative electrode, the positive electrode, the separator, and the like in an exterior body. This exterior body is not particularly limited, and any known one can be employed as long as it does not significantly impair the effects of the present invention. Specifically, although any material can be used for the exterior body, typically nickel-plated iron, stainless steel, aluminum or its alloy, nickel, titanium, or the like is used.
Also, the shape of the exterior body is arbitrary, and may be, for example, cylindrical, square, laminated, coin-shaped, large-sized, or the like.

<Battery voltage>
The non-aqueous electrolyte secondary battery of the present invention is normally used at a battery voltage of 4.0 V or higher. The battery voltage is preferably 4.1 V or higher, more preferably 4.15 V or higher, and most preferably 4.2 V or higher. This is because the energy density of the battery can be increased by increasing the battery voltage.

On the other hand, increasing the battery voltage raises the potential of the positive electrode, which causes a problem of increased side reactions on the surface of the positive electrode. The above problems can be solved by using the electrolyte and battery of the present invention. However, if the voltage is too high, the amount of side reaction on the surface of the positive electrode becomes too large, degrading the battery characteristics. Therefore, the upper limit of battery voltage is preferably 5 V or less, more preferably 4.8 V or less.
V or less, and most preferably 4.6 V or less.

<Reasons why the present invention is effective>
The reason why the present invention is effective is not yet clear, but is presumed as follows.
First, attempts have been made to use high-capacity lithium-transition metal compounds as positive electrode active materials in batteries for automobiles. Such a high-capacity lithium-transition metal-based compound can be achieved, for example, by increasing the amount of Ni.

However, it has been found that when such a lithium transition metal compound is used as a non-aqueous electrolyte secondary battery, the capacity and capacity retention rate after high-temperature storage are low, and the amount of gas generated from the battery increases. was done.
When the inventors examined this, the following mechanism was inferred.
That is, when the amount of Ni in the lithium transition metal compound is increased, the oxygen atoms in the crystal of the lithium transition metal compound during charging become unstable and become activated. For this reason, it is considered that the oxidizing power of the positive electrode is increased. In addition, the lithium transition metal compound in such a situation reacts with the electrolyte in the battery to generate gas, which deteriorates the surface of the lithium transition metal compound and reduces the capacity. inferred.

In contrast, the inventors have found that by including a specific silyl ester compound in the electrolytic solution,
It has been found that the oxidizing power on the surface of the positive electrode can be reduced, and the decrease in capacity and capacity retention rate after high-temperature storage, the amount of gas generated due to the decomposition of the solvent of the electrolytic solution, and the amount of metal elution can be suppressed.
Although the reason for this is still unclear, the specific silyl ester compound used in the non-aqueous electrolytic solution decomposes into a silyl fluoride compound, and this silyl fluoride compound has increased oxidizing power. Presumably, it reacts with the surface of the compound to reduce the oxidizing power of the surface of the positive electrode, thereby suppressing the decrease in capacity and capacity retention rate after high-temperature storage and the generation of gas due to the decomposition of the electrolytic solution.

Specific embodiments of the present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.
The abbreviations of the compounds used in this example are shown below.
Compound 1: Trimethylsilyl methanesulfonate Compound 2: Lithium difluorophosphate

[Evaluation of non-aqueous electrolyte secondary battery]
・Initial charging and discharging In a constant temperature bath at 25 ° C, a sheet-shaped non-aqueous electrolyte secondary battery is discharged at 0.05 C (the current value for discharging the rated capacity by the discharge capacity of 1 hour rate in 1 hour is 1 C. The same applies hereinafter. ) to 3.7V, then constant-current-constant-voltage charge to 4.2V at 0.2C, then 0.2C.
Constant current discharge to 2.5V was performed at 2C.

Furthermore, the non-aqueous electrolyte secondary battery was stabilized by storing at 60° C. for 12 hours after constant current-constant voltage charging at 0.2 C to 4.1 V. After that, constant current discharge to 2.5V was performed at 25° C., and then constant current-constant voltage charge was performed at 0.2C to a voltage of 4.2V. after that,
Constant current discharge was performed at 0.2 C to 2.5 V, and the discharge capacity at this time was taken as the pre-storage capacity (A). Next, constant current-constant voltage charging was performed at 0.2 C to a voltage of 4.2 V to complete initial charging and discharging. The volume of the non-aqueous electrolyte secondary battery before and after the initial charge/discharge is immersed in an ethanol bath to measure the volume, and the amount of generated gas is obtained from the volume change before and after the initial charge/discharge. The ratio of the initial gas reduction amount due to "initial gas suppression rate" (for example, initial gas suppression rate (%) of Example 1 = {(initial gas amount of Comparative Example 1 - initial gas amount of Example 1) / Initial gas amount of Comparative Example 1}×100).

- Storage test The non-aqueous electrolyte secondary battery after the initial charge/discharge was stored at a high temperature at 85°C for 24 hours. After that, after sufficiently cooling the non-aqueous electrolyte secondary battery, it is immersed in an ethanol bath to measure the volume, and the amount of generated gas is obtained from the volume change before and after the storage test. The ratio of the amount of storage gas reduction due to the "storage gas suppression rate" (for example, storage gas suppression rate (%) of Example 1 = {(storage gas amount of Comparative Example 1 - storage gas amount of Example 1) / Amount of stored gas in Comparative Example 1}×100). This non-aqueous electrolyte secondary battery was heated to 2.5 at 0.2C in a constant temperature bath at 25°C.
4. Residual capacity after storage (B) is defined as the discharge capacity when constant current discharge is performed up to V;
The discharge capacity after constant current-constant voltage charging at 0.2 C to a voltage of 2 V and then constant current discharging at 0.2 C to 2.5 V was defined as the post-storage recovery capacity (C). The ratio of the remaining capacity after storage (B) to the capacity before storage (A) is defined as the "capacity remaining ratio after storage", and the ratio of the recovered capacity after storage (C) to the capacity before storage (A) is defined as the "capacity recovery after storage rate.
Note that the larger the capacity residual ratio after storage and the capacity recovery ratio after storage, the better, and the larger the initial gas suppression ratio and the storage gas suppression ratio, the smaller the swelling of the battery, which is preferable.

[Examples 1 and 2, Comparative Examples 1 to 7]
[Preparation of non-aqueous electrolyte secondary battery]
<Preparation of non-aqueous electrolytic solution>
Non-aqueous electrolysis in which 1 mol/L (concentration in the non-aqueous electrolytic solution) of sufficiently dried LiPF ₆ was dissolved in a mixture of ethylene carbonate and ethyl methyl carbonate (volume ratio 3:7) under a dry argon atmosphere. Based on the liquid, 1% by mass of compound 1 (as the content in the non-aqueous electrolyte) is dissolved, and 0.5% by mass of compound 2 is dissolved (as the content in the non-aqueous electrolyte). Three kinds of non-aqueous electrolytic solutions were prepared, one in which compound 1 and compound 2 were not dissolved.
Using this non-aqueous electrolyte, a non-aqueous electrolyte secondary battery was produced by the following method, and the following evaluations were carried out.

<Preparation of positive electrode>
Lithium-nickel-manganese-cobalt composite oxide as a positive electrode active material is NMC622 (
_{Li1.00Ni0.61Mn0.19Co0.20O2 :} Ni/ _{( Ni} +Mn+ _Co )
molar _{ratio =} 0.61, _NMC532 ( _{Li1.05Ni0.52Mn0.29Co0.20}
O ₂ :Ni/(Ni+Mn+Co) molar ratio=0.52), or NMC111 (Li _1.
05 Ni _0.34 Mn _0.33 Co _0.33 O ₂ : Ni/(Ni+Mn+Co) molar ratio=
0.34) were used. 90 parts by mass of various positive electrode active materials, 7 parts by mass of acetylene black as a conductive material, 3 parts by mass of polyvinylidene fluoride (PVdF) as a binder, and 0.07 parts by mass of polyvinylpyrrolidone as a dispersant. , N-methyl-2-pyrrolidone, mixed and slurried, uniformly coated on an aluminum foil having a thickness of 15 μm, dried, and roll-pressed to a positive electrode (hereinafter, this positive electrode may be referred to as a positive electrode 1). Yes.) The plate density of the positive electrode was 3.3 g/cm ³ .

<Production of negative electrode>
49 parts by mass of graphite powder, 50% aqueous dispersion of sodium carboxymethylcellulose as a thickening agent (concentration of 1% by mass of sodium carboxymethylcellulose)
Parts by mass and 1 part by mass of an aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber: 49% by mass) as a binder were added and mixed with a disperser to form a slurry. The resulting slurry was uniformly applied to a copper foil having a thickness of 10 μm, dried, and roll-pressed to form a negative electrode.

<Production of non-aqueous electrolyte secondary battery>
The above positive electrode, negative electrode, and polyolefin separator were laminated in the order of negative electrode, separator, and positive electrode. Wrapping the thus obtained battery element with an aluminum laminate film,
After injecting the non-aqueous electrolyte, the sheet-like non-aqueous electrolyte secondary battery was produced by vacuum sealing. Nine types of non-aqueous electrolyte secondary batteries were produced by combining three types of positive electrode active material compositions and three types of non-aqueous electrolyte solutions with and without compound 1 and compound 2 as shown in Table 1. and non-aqueous electrolyte secondary batteries of Comparative Examples 1 to 7.

Table 1 shows the relative value of the residual capacity after storage, the residual capacity ratio after storage, and the capacity recovery ratio after storage, with Example 1 being 100. As is clear from Table 1, when the compound 1 according to the present invention is added to the non-aqueous electrolyte of the non-aqueous electrolyte secondary battery containing the positive electrode active material of the specific composition according to the present invention (Example 1 and Example 2) The residual capacity after storage, the capacity residual ratio after storage, and the capacity recovery ratio after storage are improved compared to the case where Compound 1 was not added (Comparative Example 1). On the other hand, in the non-aqueous electrolyte secondary battery containing the positive electrode active material outside the scope of the present invention, compared to the case where the non-aqueous electrolyte does not contain compound 1 (Comparative Examples 4 and 7), the compound 1 In Comparative Examples 2, 3 and 5, 6), the above characteristics tend to deteriorate.

Table 2 shows the initial gas suppression rate and the storage gas suppression rate. The values of Examples 1 and 2 are based on the value of Comparative Example 1, the values of Comparative Examples 2 and 3 are based on the value of Comparative Example 4, and the values of Comparative Examples 5 and 6 are
The value of Comparative Example 7 was used as a reference. As is clear from Table 2, when the compound 1 according to the present invention is added to the non-aqueous electrolyte of the non-aqueous electrolyte secondary battery containing the positive electrode active material of the specific composition according to the present invention (
In Examples 1 and 2), the initial gas suppression rate and storage gas suppression rate are improved compared to the case where Compound 1 is not added (Comparative Example 1). On the other hand, in the non-aqueous electrolyte secondary battery containing the positive electrode active material outside the scope of the present invention, compared to the case where the non-aqueous electrolyte does not contain compound 1 (Comparative Examples 4 and 7), the compound 1 The extent of improvement by Comparative Examples 2, 3 and 5, 6) is obviously small.

The non-aqueous electrolyte secondary battery of the present invention is useful because it can improve initial characteristics and durability.
Therefore, the non-aqueous electrolyte secondary battery of the present invention can be used for various known applications. Specific examples include notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, mobile faxes, mobile copiers, mobile printers, headphone stereos, video movies, liquid crystal televisions, handy cleaners, portable CDs, and minidiscs. , walkie-talkies, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power sources, motors, automobiles, motorcycles, motorized bicycles, bicycles, lighting fixtures, toys, game devices, clocks, power tools, strobes, cameras, homes backup power supply for office, backup power supply for office, load leveling power supply, natural energy storage power supply,
A lithium ion capacitor etc. are mentioned.

Claims (5)

A non-aqueous electrolyte secondary battery comprising a positive electrode having a positive electrode active material capable of absorbing and releasing metal ions, a negative electrode having a negative electrode active material capable of absorbing and releasing metal ions, and a non-aqueous electrolyte, ,
The positive electrode active material contains a lithium transition metal compound represented by the following compositional formula (I), the non-aqueous electrolytic solution contains a compound represented by the following formula (II),
The non-aqueous electrolytic solution is at least one selected from the group consisting of a chain sulfonate, a cyclic sulfonate, a chain sulfate, a cyclic sulfate, a chain sulfite, a cyclic sulfite, and an organic compound having a cyano group. containing compounds of the species
A non-aqueous electrolyte secondary battery , wherein the amount of sulfate contained in the positive electrode active material is 15 μmol/g or more .
Li _1+x M ³ O ₂ (I)
(In the above composition formula (I), x is −0.1 or more and 0.5 or less, M ³ is a plurality of elements containing at least Ni and Co, and the Ni/M ³ molar ratio is 0.55 or more. 1.0 or less.)

(In formula (II), X represents a boron atom, a phosphorus atom or a sulfur atom, a and b represent integers of 0 to 2, R ¹ is an alkyl group having 1 to 10 carbon atoms, an alkenyl group or an alkynyl group, or an aryl group or alkoxy group having 6 to 18 carbon atoms, hydrogen atoms bonded to carbon atoms may be substituted with halogen atoms, and may have an ether bond, R ² to R ⁴ are each independently represents an alkyl group, alkenyl group or alkynyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 18 carbon atoms, and c represents an integer of 1 to 3.) The non-aqueous electrolytic solution according to claim 1, wherein the content of the compound represented by the formula (II) is 0.001% by mass or more and 10% by mass or less with respect to 100% by mass of the non-aqueous electrolytic solution. secondary battery. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the non-aqueous electrolyte contains a monofluorophosphate and/or a difluorophosphate. Any one of claims 1 to 3, wherein the total content of monofluorophosphate and difluorophosphate is 0.001% by mass or more and 10% by mass or less with respect to 100% by mass of the non-aqueous electrolyte. The non-aqueous electrolyte secondary battery according to the item. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 4 , wherein the positive electrode has a plate density of 3.0 g/cm ³ or more.