JP2020038783A - Nonaqueous electrolyte for battery, and lithium secondary battery - Google Patents

Abstract

To provide a nonaqueous electrolyte for a battery, which can reduce battery resistance after preservation.SOLUTION: A nonaqueous electrolyte for a battery contains: a nonaqueous solvent that includes 1,2-dimethoxyethane; an electrolyte; and an additive S that is at least one kind selected from a group comprising cyclic sulfate ester having a specific structure, cyclic sulfonic acid ester, sulfonic acid lithium salt and a sulfonic acid fluoride. The content of 1,2-dimethoxyethane is in the range of 10-40 vol.% with respect to the total amount of the nonaqueous solvent.SELECTED DRAWING: None

Description

  The present disclosure relates to a non-aqueous electrolyte for a battery and a lithium secondary battery.

In some cases, 1,2-dimethoxyethane is contained in a non-aqueous electrolyte used for a battery (for example, a lithium secondary battery).
For example, Patent Document 1 discloses a non-aqueous electrolyte containing a cyclic carbonate derivative and 1,2-dimethoxyethane.

JP 2010-86722 A

1,2-Dimethoxyethane is effective as a low-viscosity solvent.
However, in a battery using a non-aqueous electrolyte containing 1,2-dimethoxyethane, the battery resistance may increase.
An object of one embodiment of the present disclosure is to provide a non-aqueous electrolyte for a battery that can reduce battery resistance while being a non-aqueous electrolyte containing 1,2-dimethoxyethane.
An object of another embodiment of the present disclosure is to provide a lithium secondary battery in which the battery resistance is reduced while being a lithium secondary battery using a non-aqueous electrolyte containing 1,2-dimethoxyethane. is there.

Means for solving the above problems include the following aspects.
<1> a non-aqueous solvent containing 1,2-dimethoxyethane,
An electrolyte,
A compound represented by the following formula (S1), a compound represented by the following formula (S2), a compound represented by the following formula (S3), a compound represented by the following formula (S4), and a compound represented by the following formula (S5) And at least one additive S selected from the group consisting of compounds represented by
Non-aqueous electrolyte for batteries containing.

In the formula (S1), R ^{11 to} R ¹⁴ each independently represent a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a group represented by the formula (1a), or a group represented by the formula (1b). Represents In the formulas (1a) and (1b), * represents a bonding position.
In the formula (S2), R ^{21 to} R ²⁴ each independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.
In Formula (S3), R ^{31 to} R ³⁶ each independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.
In the formula (S4), R ⁴¹ represents a fluorine atom, an alkoxy group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.
In the formula (S5), R ⁵¹ represents a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.

<2> The nonaqueous electrolytic solution for a battery according to <1>, wherein the content of the 1,2-dimethoxyethane is 10% by volume to 40% by volume based on the total amount of the nonaqueous solvent.
<3> The additive S is at least selected from the group consisting of a compound represented by the formula (S1), a compound represented by the formula (S2), and a compound represented by the formula (S3). The non-aqueous electrolyte for a battery according to <1> or <2>, which contains one type.
<4> The non-aqueous battery for a battery according to any one of <1> to <3>, wherein the additive S includes at least one selected from the group consisting of compounds represented by the formula (S1). Electrolyte.
<5> In the formula (S1), the R ¹¹ is a group represented by the formula (1a) or a group represented by the formula (1b), and the R ¹² to R ¹⁴ are each independently A hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a group represented by the formula (1a), or a group represented by the formula (1b). The non-aqueous electrolyte for a battery according to the above.
<6> The battery according to any one of <1> to <5>, wherein the content of the additive S is 0.001% by mass to 10% by mass based on the total amount of the nonaqueous electrolyte for a battery. For non-aqueous electrolyte.
<7> The nonaqueous electrolytic solution for a battery according to any one of <1> to <6>, wherein the nonaqueous solvent further includes a cyclic carbonate compound and a chain carbonate compound.
<8> The positive electrode,
Lithium metal, lithium-containing alloy, metal or alloy capable of being alloyed with lithium, oxide capable of doping / dedoping lithium ion, transition metal nitride capable of doping / dedoping lithium ion, and lithium A negative electrode containing, as a negative electrode active material, at least one selected from the group consisting of carbon materials capable of doping and undoping ions;
A non-aqueous electrolyte for a battery according to any one of <1> to <7>,
Including lithium secondary batteries.
<9> A lithium secondary battery obtained by charging and discharging the lithium secondary battery according to <8>.

According to one embodiment of the present disclosure, there is provided a nonaqueous electrolytic solution for a battery that can reduce battery resistance after storage, while being a nonaqueous electrolytic solution containing 1,2-dimethoxyethane.
According to another aspect of the present disclosure, there is provided a lithium secondary battery in which the battery resistance after storage is reduced while being a lithium secondary battery using a non-aqueous electrolyte containing 1,2-dimethoxyethane. Is done.

FIG. 1 is a schematic perspective view illustrating an example of a laminated battery, which is an example of a lithium secondary battery of the present disclosure. FIG. 2 is a schematic cross-sectional view in a thickness direction of a laminated electrode body housed in the laminated battery shown in FIG. 1. 1 is a schematic cross-sectional view illustrating an example of a coin-type battery, which is another example of the lithium secondary battery of the present disclosure. 5 is a graph showing the gas generation amount (cm ³ ) when the nonaqueous electrolytes of Comparative Example 1 and Examples 1 to 4 are used.

In this specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit and an upper limit.
In the present specification, the amount of each component in the composition is, if there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, the total amount of the plurality of substances present in the composition Means

(Non-aqueous electrolyte for batteries)
Non-aqueous electrolyte for batteries of the present disclosure (hereinafter, also simply referred to as "non-aqueous electrolyte")
A non-aqueous solvent containing 1,2-dimethoxyethane,
An electrolyte,
A compound represented by the following formula (S1), a compound represented by the following formula (S2), a compound represented by the following formula (S3), a compound represented by the following formula (S4), and a compound represented by the following formula (S5) And at least one additive S selected from the group consisting of compounds represented by
It contains.

In the formula (S1), R ^{11 to} R ¹⁴ each independently represent a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a group represented by the formula (1a), or a group represented by the formula (1b). Represents In the formulas (1a) and (1b), * represents a bonding position.
In the formula (S2), R ^{21 to} R ²⁴ each independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.
In Formula (S3), R ^{31 to} R ³⁶ each independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.
In the formula (S4), R ⁴¹ represents a fluorine atom, an alkoxy group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.
In the formula (S5), R ⁵¹ represents a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.

According to the non-aqueous electrolyte of the present disclosure, the battery resistance can be reduced even though the non-aqueous electrolyte contains 1,2-dimethoxyethane.
The reason for such an effect is assumed as follows.

In a battery using a non-aqueous electrolyte containing 1,2-dimethoxyethane (hereinafter, also referred to as DME), battery resistance may increase. The reason for the increase in battery resistance is that DME is strongly solvated by ions (eg, lithium ions in a lithium secondary battery) by bidentate coordination and co-inserted with the ions into the negative electrode; Decomposed at the positive electrode, causing gas generation and / or deposit formation; and the like.
In this regard, the non-aqueous electrolyte of the present disclosure contains a non-aqueous solvent containing DME and contains an additive S. Thereby, the additive S forms good-quality coatings on the negative electrode and the positive electrode, and these coatings suppress the above co-insertion into the negative electrode, and prevent gas generation and / or deposit formation on the positive electrode. It is considered that the increase in battery resistance due to DME is suppressed as a result.

<Non-aqueous solvent>
The non-aqueous electrolyte of the present disclosure contains a non-aqueous solvent.
Non-aqueous solvents include DME (i.e., 1,2-dimethoxyethane).
DME is a low viscosity solvent. Therefore, when the non-aqueous solvent contains DME, the handleability of the non-aqueous electrolyte is improved.

The content of DME is preferably 10% by mass to 40% by mass based on the total amount of the nonaqueous solvent.
When the content of DME is 10% by mass or more based on the total amount of the nonaqueous solvent, the handleability of the nonaqueous electrolyte is further improved.
Generally, when the content of DME is 10% by mass or more with respect to the total amount of the nonaqueous solvent, the above co-insertion into the negative electrode, and gas generation or formation of deposits on the positive electrode Becomes more conspicuous, and as a result, the battery resistance tends to further increase. However, the non-aqueous electrolyte solution of the present disclosure contains the additive S, so that even if the DME content is 10% by mass or more based on the total amount of the non-aqueous solvent, the battery resistance increases. It can be suppressed effectively. That is, when the content of DME is 10% by mass or more with respect to the total amount of the non-aqueous solvent, the range of improvement by the additive S (that is, the range of reduction in battery resistance) becomes larger. When the content of DME is 20% by mass or more based on the total amount of the non-aqueous solvent, the range of improvement by the additive S is further increased.
On the other hand, when the content of DME is 40% by mass or less based on the total amount of the non-aqueous solvent, an increase in battery resistance is suppressed because the content of DME itself is small.

The non-aqueous solvent may further include a solvent species other than DME.
As the solvent species other than DME, various known solvents can be appropriately selected.
As the solvent species other than DME, for example, the solvent species described in paragraphs 0069 to 0087 of JP-A-2017-45723 can be used.

It is preferable that the non-aqueous solvent further contains a cyclic carbonate compound and a chain carbonate compound.
In this case, each of the cyclic carbonate compound and the chain carbonate compound contained in the non-aqueous solvent may be only one kind or two or more kinds.

Examples of the cyclic carbonate compound include ethylene carbonate (hereinafter, also referred to as “EC”), propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, and 2,3-pentyne. Lencarbonate and the like can be mentioned.
Of these, ethylene carbonate and propylene carbonate, which have a high dielectric constant, are preferred. In the case of a battery using a negative electrode active material containing graphite, the non-aqueous solvent more preferably contains ethylene carbonate.

  Examples of the chain carbonate compound include dimethyl carbonate (hereinafter, also referred to as “DMC”), ethyl methyl carbonate (hereinafter, also referred to as “EMC”), diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate , Methyl butyl carbonate, ethyl butyl carbonate, dibutyl carbonate, methyl pentyl carbonate, ethyl pentyl carbonate, dipentyl carbonate, methyl heptyl carbonate, ethyl heptyl carbonate, diheptyl carbonate, methyl hexyl carbonate, ethyl hexyl carbonate, dihexyl carbonate, methyl octyl carbonate, ethyl octyl carbonate Octyl carbonate, dioctyl carbonate, etc. And the like.

  As a combination of a cyclic carbonate and a chain carbonate, specifically, ethylene carbonate and dimethyl carbonate, ethylene carbonate and methyl ethyl carbonate, ethylene carbonate and diethyl carbonate, propylene carbonate and dimethyl carbonate, propylene carbonate and methyl ethyl carbonate, propylene carbonate and Diethyl carbonate, ethylene carbonate, propylene carbonate, and methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and diethyl carbonate, ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate, ethylene carbonate, dimethyl carbonate, and diethyl carbonate, ethylene carbonate and methyl ethyl carbonate Diethyl carbonate, ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, methyl ethyl carbonate And diethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate.

  The mixing ratio of the cyclic carbonate compound and the chain carbonate compound is represented by a volume ratio, and the ratio of the cyclic carbonate compound to the chain carbonate compound is, for example, 5:95 to 80:20, preferably 10:90 to 70:30, and more preferably. Is from 20:80 to 60:40. With such a ratio, the increase in the viscosity of the non-aqueous electrolyte can be suppressed, and the degree of dissociation of the electrolyte can be increased. Therefore, the conductivity of the non-aqueous electrolyte relating to the charge and discharge characteristics of the battery can be increased. . Further, the solubility of the electrolyte can be further increased. Therefore, a non-aqueous electrolyte having excellent electrical conductivity at normal temperature or low temperature can be obtained, and the load characteristics of the battery at normal temperature to low temperature can be improved.

The non-aqueous solvent may contain other compounds other than the cyclic carbonate compound and the chain carbonate compound.
In this case, the other compound contained in the non-aqueous solvent may be only one kind or two or more kinds.
Other compounds include a cyclic carboxylate compound (eg, γ-butyrolactone), a cyclic sulfone compound, a cyclic ether compound, a linear carboxylate compound, a linear ether compound, a linear phosphate ester compound, an amide compound, and a linear carbamate. Compounds, cyclic amide compounds, cyclic urea compounds, boron compounds, polyethylene glycol derivatives, and the like.
Regarding these compounds, the description in paragraphs 0069 to 0087 of JP-A-2017-45723 can be appropriately referred to.

  The total content of the cyclic carbonate compound and the chain carbonate compound is preferably from 60% by volume to 90% by volume, more preferably from 60% by volume to 80% by volume, based on the total amount of the nonaqueous solvent.

<Electrolyte>
The non-aqueous electrolyte of the present disclosure contains an electrolyte.
The electrolyte preferably contains LiPF _6.
In this case, the ratio of LiPF _{6 in} the electrolyte is preferably 1% by mass to 100% by mass, more preferably 10% by mass to 100% by mass, and still more preferably 50% by mass to 100% by mass.

The concentration of the electrolyte in the nonaqueous electrolyte of the present disclosure is preferably from 0.1 mol / L to 3 mol / L, and more preferably from 0.5 mol / L to 2 mol / L.
Further, the concentration of LiPF ₆ in the nonaqueous electrolyte of the present disclosure is preferably from 0.1 mol / L to 3 mol / L, more preferably from 0.5 mol / L to 2 mol / L.

The electrolyte may include a compound other than LiPF ₆ .
Compounds other than LiPF ₆ include;
(C ₂ H ₅ ) ₄ NPF ₆ , (C ₂ H ₅ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NAsF ₆ , (C ₂ H ₅ ) ₄ N ₂ SiF ₆ , (C ₂ H ₅ ) ₄ NOSO ₂ C _k F _{(2 k + 1)} (k = 1 to 8), (C ₂ H ₅ ) ₄ NPF _n [C _k F _{(2 k + 1)} ] _(6-n) ( tetraalkylammonium salts such as n = 1 to 5, k = 1 to 8);
_{LiBF 4, LiClO 4, LiAsF 6} , Li 2 SiF 6, LiOSO 2 C k F (2k + 1) (k = 1~8 _{integer), LiPF n [C k F} (2k + 1)] (6-n) (n = 1 to 5, k = 1 to 8), LiC (SO ₂ R ⁷ ) (SO ₂ R ⁸ ) (SO ₂ R ⁹ ), LiN (SO ₂ OR ¹⁰ ) (SO ₂ OR ¹¹ ), LiN (SO ^{_{2 R 12) (SO 2 R}} 13) ( wherein ^R 7 ^{to R 13} may be the same or different from each other, a fluorine atom or a perfluoroalkyl group having 1 to 8 carbon atoms) lithium salts such as (i.e. , Lithium salts other than LiPF ₆ );
And the like.

<Additive S>
The non-aqueous electrolyte of the present disclosure contains the additive S.
The additive S is a compound represented by the following formula (S1), a compound represented by the following formula (S2), a compound represented by the following formula (S3), a compound represented by the following formula (S4), and It is at least one selected from the group consisting of compounds represented by the following formula (S5).

  The content of the additive S is preferably 0.001% by mass to 10% by mass, more preferably 0.001% by mass to 5.0% by mass, and more preferably 0.001% by mass to the total amount of the nonaqueous electrolyte. 3.0% by mass is more preferable, 0.01% by mass to 3.0% by mass is more preferable, 0.1 to 3.0% by mass is more preferable, and 0.1 to 2.0% by mass is more preferable. 0.1-1.0 mass% is more preferable.

(Compound represented by Formula (S1))
The compound represented by the formula (S1) is as follows.

In the formula (S1), R ^{11 to} R ¹⁴ each independently represent a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a group represented by the formula (1a), or a group represented by the formula (1b). Represents In the formulas (1a) and (1b), * represents a bonding position.

In the formula (S1), the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{11 to} R ¹⁴ may be a straight-chain hydrocarbon group or a hydrocarbon group having a branched and / or cyclic structure. It may be.

In the formula (S1), specific examples of the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{11 to} R ¹⁴ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a 1-ethylpropyl group, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-methylbutyl, 3,3-dimethylbutyl, n-pentyl, isopentyl, neopentyl, 1-methylpentyl, n-butyl Alkyl groups such as hexyl group, isohexyl group, sec-hexyl group and tert-hexyl group; vinyl group, 1-propenyl group, allyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, pentenyl group, hexenyl Alkenyl groups such as a group, isopropenyl group, 2-methyl-2-propenyl group, 1-methyl-2-propenyl group, 2-methyl-1-propenyl group; etc. And the like.

In Formula (S1), the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{11 to} R ¹⁴ is preferably an alkyl group or an alkenyl group, and more preferably an alkyl group.
In formula (S1), the number of carbon atoms of the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{11 to} R ¹⁴ is preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

  Specific examples of the compound represented by the formula (S1) include compounds represented by the following formulas (S1-1) to (S1-4) (hereinafter, compounds (S1-1) to (S1), respectively) -4)), but the compound represented by the formula (S1) is not limited to these specific examples.

(Compound represented by Formula (S2))
The compound represented by the formula (S2) is as follows.

In the formula (S2), R ^{21 to} R ²⁴ each independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.

In the formula (S2), the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{21 to} R ²⁴ may be a straight-chain hydrocarbon group or a hydrocarbon group having a branched and / or cyclic structure. It may be.
In the formula (S2), specific examples of the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{21 to} R ²⁴ include a hydrocarbon group having 1 to 6 carbon atoms represented by R ^{11 to} R ¹⁴ in the formula (S1). It is the same as the specific example of the hydrocarbon group.
In Formula (S2), as the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{21 to} R ²⁴ , an alkyl group or an alkenyl group is preferable, and an alkyl group is more preferable.
In the formula (S2), the number of carbon atoms of the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{21 to} R ²⁴ is preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

  In the present disclosure, a fluorinated hydrocarbon group means a hydrocarbon group substituted with at least one fluorine atom.

In the formula (S2), the C1 to C6 fluorinated hydrocarbon group represented by R ^{21 to} R ²⁴ may be a linear fluorinated hydrocarbon group, or may have a branched and / or cyclic structure. It may be a fluorinated hydrocarbon group.
In the formula (S2), specific examples of the fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R ^{21 to} R ²⁴ include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 2,2,2 -Trifluoroethyl group, 1,1,2,2-tetrafluoroethyl group, perfluoroethyl group, 2,2,3,3-tetrafluoropropyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl A fluoroalkyl group such as a perfluorohexyl group, a perfluoroisopropyl group, a perfluoroisobutyl group; a 2-fluoroethenyl group, a 2,2-difluoroethenyl group, a 2-fluoro-2-propenyl group, a 3,3 -Difluoro-2-propenyl group, 2,3-difluoro-2-propenyl group, 3,3-difluoro-2-methyl-2-propenyl group 3-fluoro-2-butenyl group, perfluorovinyl group, perfluoro propenyl group, fluoroalkenyl group, such as perfluoro butenyl group; and the like.

Wherein (S2), as a fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R ²¹ to R ^24, preferably fluorinated alkyl or fluorinated alkenyl group, more preferably a fluorinated alkyl group.
In the formula (S2), the number of carbon atoms of the fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R ^{21 to} R ²⁴ is preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

In the formula (S2), R ^{21 to} R ²⁴ are each independently preferably a hydrogen atom, a fluorine atom, a methyl group, an ethyl group, a trifluoromethyl group, or a pentafluoroethyl group, and more preferably a hydrogen atom or a methyl group. Preferably, a hydrogen atom is particularly preferred.

Specific examples of the compound represented by the formula (S2) include compounds represented by the following formulas (S2-1) to (S2-21) (hereinafter, compounds (S2-1) to (S2, respectively) -21)), but the compound represented by the formula (S2) is not limited to these specific examples.
Among them, compound (S2-1) (that is, 1,3-propene sultone; hereinafter, also referred to as “PRS”) is particularly preferable.

(Compound represented by formula (S3))
The compound represented by the formula (S3) is as follows.

In Formula (S3), R ^{31 to} R ³⁶ each independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.

In the formula (S3), the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{31 to} R ³⁶ may be a linear hydrocarbon group or a hydrocarbon group having a branched and / or cyclic structure. It may be.
In the formula (S3), specific examples of the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{31 to} R ³⁶ include those having 1 to 6 carbon atoms represented by R ^{11 to} R ¹⁴ in the formula (S1). It is the same as the specific example of the hydrocarbon group.
In Formula (S3), as the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{31 to} R ³⁶ , an alkyl group or an alkenyl group is preferable, and an alkyl group is more preferable.
In formula (S3), the number of carbon atoms of the hydrocarbon group having 1 to 6 carbon atoms represented by R ^{31 to} R ³⁶ is preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

In the formula (S3), the C1 to C6 fluorinated hydrocarbon group represented by R ^{31 to} R ³⁶ may be a linear fluorinated hydrocarbon group, or may have a branched and / or cyclic structure. It may be a fluorinated hydrocarbon group.
In the formula (S3), specific examples of the fluorocarbon group having 1 to 6 carbon atoms represented by R ^{31 to} R ³⁶ include a carbon atom 1 represented by R ^{21 to} R ²⁴ in the formula (S2). This is the same as the specific examples of the fluorohydrocarbon groups of Nos. 6 to 6.
Wherein (S3), as a fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R ³¹ to R ^36, preferably fluorinated alkyl or fluorinated alkenyl group, more preferably a fluorinated alkyl group.
In Formula (S3), the number of carbon atoms of the fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R ^{31 to} R ³⁶ is preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

In the formula (S3), each of R ^{31 to} R ³⁶ is independently preferably a hydrogen atom, a fluorine atom, a methyl group, an ethyl group, a trifluoromethyl group, or a pentafluoroethyl group, and more preferably a hydrogen atom or a methyl group. Preferably, a hydrogen atom is particularly preferred.

Specific examples of the compound represented by the formula (S3) include compounds represented by the following formulas (S3-1) to (S3-21) (hereinafter, compounds (S3-1) to (S3, respectively) -21)), but the compound represented by the formula (S3) is not limited to these specific examples.
Among these, compound (S3-1) (that is, 1,3-propane sultone; hereinafter, also referred to as “PS”) is particularly preferable.

(Compound represented by Formula (S4))
The compound represented by the formula (S4) is as follows.

In the formula (S4), R ⁴¹ represents a fluorine atom, an alkoxy group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.

In formula (S4), the alkoxy group having 1 to 6 carbon atoms represented by R ⁴¹ may be a linear alkoxy group or an alkoxy group having a branched and / or cyclic structure.
In the formula (S4), the number of carbon atoms of the alkoxy group having 1 to 6 carbon atoms represented by R ⁴¹ is preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

In the formula (S4), the C1 to C6 fluorinated hydrocarbon group represented by R ⁴¹ may be a linear fluorinated hydrocarbon group or a fluorinated compound having a branched and / or cyclic structure. It may be a hydrocarbon group.
In the formula (S4), specific examples of the fluorocarbon group having 1 to 6 carbon atoms represented by R ⁴¹ include a fluorine-containing hydrocarbon group having 1 to 6 carbon atoms represented by R ^{21 to} R ²⁴ in the formula (S2). This is the same as the specific examples of the fluorinated hydrocarbon group.
In the formula (S4), as the C 1-6 fluorinated hydrocarbon group represented by R ⁴¹ , an alkyl fluoride group, an alkenyl fluoride group, or an alkynyl fluoride group is preferable. Alkenyl chloride groups are more preferred, and fluorinated alkyl groups are particularly preferred.
In Formula (S4), the number of carbon atoms of the fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R ⁴¹ is preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

In the formula (S4), R ⁴¹ is preferably an alkoxy group having 1 to 6 carbon atoms or a fluorinated hydrocarbon group having 1 to 6 carbon atoms, and more preferably a fluorine atom having 1 to 6 carbon atoms, from the viewpoint of further reducing battery resistance. Hydrocarbon groups are particularly preferred.

As the compound represented by the formula (S4),
Lithium trifluoromethanesulfonate or lithium pentafluoroethanesulfonate is preferred,
Particularly preferred is lithium trifluoromethanesulfonate (hereinafter, also referred to as “TFMSLi”).

(Compound represented by Formula (S5))
The compound represented by the formula (S5) is as follows.

In the formula (S5), R ⁵¹ represents a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.

In the formula (S5), the hydrocarbon group having 1 to 6 carbon atoms represented by R ⁵¹ may be a straight-chain hydrocarbon group or a hydrocarbon group having a branched and / or cyclic structure, Is also good.
In the formula (S5), specific examples of the hydrocarbon group having 1 to 6 carbon atoms represented by R ⁵¹ include a hydrocarbon group having 1 to 6 carbon atoms represented by R ^{11 to} R ¹⁴ in the formula (S1). This is the same as the specific example.
In the formula (S5), the hydrocarbon group having 1 to 6 carbon atoms represented by R ⁵¹ is preferably an alkyl group, an alkenyl group, or an alkynyl group, more preferably an alkyl group or an alkenyl group, and particularly preferably an alkyl group. .
In formula (S5), the number of carbon atoms of the hydrocarbon group having 1 to 6 carbon atoms represented by R ⁵¹ is preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

In the formula (S5), the fluorocarbon group having 1 to 6 carbon atoms represented by R ⁵¹ may be a linear fluorocarbon group, or a fluorinated hydrocarbon having a branched and / or cyclic structure. It may be a hydrocarbon group.
In the formula (S5), specific examples of the fluorocarbon group having 1 to 6 carbon atoms represented by R ⁵¹ include a fluorine-containing hydrocarbon group having 1 to 6 carbon atoms represented by R ^{22 to} R ²⁴ in the formula (S2). This is the same as the specific examples of the fluorinated hydrocarbon group.
Wherein (S5), as the fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R ^51, fluoroalkyl group, fluorinated alkenyl group, or a fluorinated alkynyl group preferably fluorinated alkyl group or fluorinated Alkenyl chloride groups are more preferred, and fluorinated alkyl groups are particularly preferred.
In the formula (S5), the number of carbon atoms of the fluorinated hydrocarbon group having 1 to 6 carbon atoms represented by R ⁵¹ is preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

In the formula (S5), R ⁵¹ is independently preferably a hydrogen atom, a fluorine atom, a methyl group, an ethyl group, a trifluoromethyl group, or a pentafluoroethyl group, more preferably a hydrogen atom or a methyl group, and Atoms are particularly preferred.

As the compound represented by the formula (S5),
Methanesulfonyl fluoride, ethanesulfonyl fluoride, propanesulfonyl fluoride, 2-propanesulfonyl fluoride, butanesulfonyl fluoride, 2-butanesulfonyl fluoride, hexanesulfonyl fluoride, trifluoromethanesulfonyl fluoride, perfluoroethanesulfonyl fluoride , Perfluoropropanesulfonyl fluoride, perfluorobutanesulfonyl fluoride, ethenesulfonyl fluoride, 1-propen-1-sulfonyl fluoride, or 2-propen-1-sulfonyl fluoride is preferred,
Methanesulfonyl fluoride, ethanesulfonyl fluoride, propanesulfonyl fluoride, 2-propanesulfonyl fluoride, butanesulfonyl fluoride, 2-butanesulfonyl fluoride, hexanesulfonyl fluoride, trifluoromethanesulfonyl fluoride, perfluoroethanesulfonyl fluoride , Perfluoropropanesulfonyl fluoride, or perfluorobutanesulfonyl fluoride is more preferable,
Methanesulfonyl fluoride, ethanesulfonyl fluoride, propanesulfonyl fluoride, 2-propanesulfonyl fluoride, butanesulfonyl fluoride, 2-butanesulfonyl fluoride, or hexanesulfonyl fluoride is more preferable.
Methanesulfonyl fluoride, ethanesulfonyl fluoride, or propanesulfonyl fluoride is more preferable,
Methanesulfonyl fluoride (hereinafter, also referred to as “MSF”) is particularly preferred.

As described above, the additive S described above has an effect of reducing the battery resistance in a battery using a nonaqueous electrolyte containing DME by forming a good-quality coating on the negative electrode and the positive electrode.
Further, the additive S described above also has an effect of suppressing gas generation (that is, gas generation due to decomposition of DME at the positive electrode) in a battery using a non-aqueous electrolyte containing DME.

  From the viewpoint of more effectively suppressing gas generation, the additive S is a group consisting of a compound represented by the formula (S1), a compound represented by the formula (S2), and a compound represented by the formula (S3). Preferably, at least one selected from the group consisting of compounds represented by the formula (S1) is included.

Also, from the viewpoint of suppressing gas generation more effectively,
In a preferred embodiment of the compound represented by the formula (S1), in the formula (S1), R ¹¹ is a hydrocarbon group having 1 to 6 carbon atoms, a group represented by the formula (1a), or a compound represented by the formula (1b). R ^{12 to} R ¹⁴ each independently represent a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a group represented by the formula (1a), or a group represented by the formula (1b) Is a group to be performed;
In a more preferred embodiment of the compound represented by the formula (S1), in the formula (S1), R ¹¹ represents a group represented by the formula (1a) or a group represented by the formula (1b); ^{12 to} R ¹⁴ are each independently a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a group represented by the formula (1a), or a group represented by the formula (1b).

  The non-aqueous electrolyte of the present disclosure is not only suitable as a non-aqueous electrolyte for a lithium secondary battery, but also a non-aqueous electrolyte for a primary battery, a non-aqueous electrolyte for an electrochemical capacitor, and an electric double layer capacitor. And an electrolytic solution for an aluminum electrolytic capacitor.

[Lithium secondary battery]
A lithium secondary battery according to the present disclosure includes a positive electrode, a negative electrode, and the nonaqueous electrolyte according to the present disclosure.

<Negative electrode>
The negative electrode may include a negative electrode active material and a negative electrode current collector.
As the negative electrode active material of the negative electrode, metallic lithium, a lithium-containing alloy, a metal or alloy capable of being alloyed with lithium, an oxide capable of doping / undoping lithium ions, and capable of doping / dedoping lithium ions At least one selected from the group consisting of a transition metal nitride and a carbon material capable of doping / dedoping lithium ions (may be used alone, or a mixture containing two or more thereof may be used. Good) can be used.
Examples of the metal or alloy that can be alloyed with lithium (or lithium ion) include silicon, a silicon alloy, tin, and a tin alloy. Further, lithium titanate may be used.
Among these, carbon materials capable of doping / dedoping lithium ions are preferable. Examples of such a carbon material include carbon black, activated carbon, graphite materials (artificial graphite, natural graphite), and amorphous carbon materials. The form of the carbon material may be any of a fibrous form, a spherical form, a potato form, and a flake form.

Specific examples of the amorphous carbon material include hard carbon, coke, mesocarbon microbeads (MCMB) fired at 1500 ° C. or lower, mesophase pitch carbon fiber (MCF), and the like.
Examples of the graphite material include natural graphite and artificial graphite. As artificial graphite, graphitized MCMB, graphitized MCF and the like are used. As the graphite material, a material containing boron or the like can be used. As the graphite material, a material coated with a metal such as gold, platinum, silver, copper, tin, etc., a material coated with amorphous carbon, or a mixture of amorphous carbon and graphite can also be used.

These carbon materials may be used alone or in combination of two or more.
As the carbon material, a carbon material having a plane distance d (002) of (002) plane measured by X-ray analysis of 0.340 nm or less is particularly preferable. Further, as the carbon material, graphite having a true density of 1.70 g / cm ³ or more, or a highly crystalline carbon material having properties close thereto is also preferable. The use of such a carbon material can further increase the energy density of the battery.

The material of the negative electrode current collector in the negative electrode is not particularly limited, and any known material can be used.
Specific examples of the negative electrode current collector include metal materials such as copper, nickel, stainless steel, and nickel-plated steel. Among them, copper is particularly preferable from the viewpoint of ease of processing.

<Positive electrode>
The positive electrode may include a positive electrode active material and a positive electrode current collector.
As the positive electrode active material in the positive electrode, transition metal oxides or transition metal sulfides such as MoS ₂ , TiS ₂ , MnO ₂ , V ₂ O ₅ , LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , and LiNi _X Co _(1-X) O ₂ [0 <X <1], Li _{1 + α} Me _1-α O ₂ having α-NaFeO ₂ type crystal structure (Me is a transition metal element containing Mn, Ni and Co, 1.0 ≦ (1 + α) / ( 1-α) ≦ 1.6), LiNi x Co y Mn z O 2 [x + y + z = 1,0 < x <1,0 <y <1,0 <z <1 ] (e.g., A composite oxide composed of lithium and a transition metal, such as LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ), LiFePO ₄ , LiMnPO ₄ , Polyaniline, Li thiophene, polypyrrole, polyacetylene, polyacene, dimercaptothiadiazoles, conductive polymer materials such as polyaniline complex thereof. Among these, a composite oxide composed of lithium and a transition metal is particularly preferable. When the negative electrode is lithium metal or a lithium alloy, a carbon material can be used as the positive electrode. In addition, a mixture of a composite oxide of lithium and a transition metal and a carbon material can be used as the positive electrode.
One type of the positive electrode active material may be used, or two or more types may be mixed and used. When the positive electrode active material has insufficient conductivity, the positive electrode can be used together with a conductive auxiliary to form a positive electrode. Examples of the conductive auxiliary agent include carbon materials such as carbon black, amorphous whiskers, and graphite.

The material of the positive electrode current collector in the positive electrode is not particularly limited, and any known material can be used.
Specific examples of the positive electrode current collector include, for example, metal materials such as aluminum, aluminum alloy, stainless steel, nickel, titanium, and tantalum; carbon materials such as carbon cloth and carbon paper;

<Separator>
The lithium secondary battery of the present disclosure preferably includes a separator between the negative electrode and the positive electrode.
The separator is a film that electrically insulates the positive electrode and the negative electrode and transmits lithium ions, and examples thereof include a porous film and a polymer electrolyte.
As the porous film, a microporous polymer film is suitably used, and examples of the material include polyolefin, polyimide, polyvinylidene fluoride, polyester, and the like.
In particular, a porous polyolefin is preferable, and specific examples thereof include a porous polyethylene film, a porous polypropylene film, and a multilayer film of a porous polyethylene film and a polypropylene film. Another resin having excellent thermal stability may be coated on the porous polyolefin film.
Examples of the polymer electrolyte include a polymer in which a lithium salt is dissolved, a polymer swelled with an electrolytic solution, and the like.
The non-aqueous electrolyte of the present disclosure may be used for the purpose of obtaining a polymer electrolyte by swelling a polymer.

<Structure of battery>
The lithium secondary battery of the present disclosure can take various known shapes, and can be formed into a cylindrical shape, a coin shape, a square shape, a laminate shape, a film shape, or any other shape. However, the basic structure of the battery is the same regardless of the shape, and the design can be changed according to the purpose.

Examples of the lithium secondary battery of the present disclosure include a laminated battery.
FIG. 1 is a schematic perspective view illustrating an example of a laminated battery that is an example of the lithium secondary battery of the present disclosure. FIG. 2 is a diagram illustrating a thickness of a laminated electrode body housed in the laminated battery illustrated in FIG. It is a schematic sectional drawing of a direction.
The laminated battery shown in FIG. 1 contains a non-aqueous electrolyte (not shown in FIG. 1) and a laminated electrode body (not shown in FIG. 1), and the peripheral edge is sealed. And a laminate exterior body 1 the inside of which is sealed. As the laminate case 1, for example, a laminate case made of aluminum is used.
As shown in FIG. 2, the laminated electrode body accommodated in the laminate exterior body 1 includes a laminated body in which a positive electrode plate 5 and a negative electrode plate 6 are alternately laminated with a separator 7 interposed therebetween. And a separator 8 surrounding the periphery. The non-aqueous electrolyte of the present disclosure is impregnated in the positive electrode plate 5, the negative electrode plate 6, the separator 7, and the separator 8.
Each of the plurality of positive plates 5 in the stacked electrode body is electrically connected to the positive terminal 2 via a positive tab (not shown). It protrudes outward from the peripheral end (FIG. 1). The portion where the positive electrode terminal 2 protrudes at the peripheral end of the laminate exterior body 1 is sealed with an insulating seal 4.
Similarly, the plurality of negative electrodes 6 in the stacked electrode body are all electrically connected to the negative electrode terminal 3 via a negative electrode tab (not shown), and a part of the negative electrode terminal 3 is It protrudes outward from the peripheral end of the body 1 (FIG. 1). The portion where the negative electrode terminal 3 protrudes at the peripheral end of the laminate exterior body 1 is sealed with an insulating seal 4.
In the laminated battery according to the above-described example, the number of the positive electrode plates 5 is five and the number of the negative electrode plates 6 is six, and the positive electrode plate 5 and the negative electrode plate 6 are interposed with the separator 7 therebetween. The outer layers are all laminated so as to be the negative electrode plate 6. However, the number of positive electrodes, the number of negative electrodes, and the arrangement in the laminated battery are not limited to this example, and it goes without saying that various changes may be made.

Another example of the lithium secondary battery of the present disclosure includes a coin-type battery.
FIG. 3 is a schematic perspective view illustrating an example of a coin-type battery which is another example of the lithium secondary battery of the present disclosure.
In the coin-type battery shown in FIG. 3, the disc-shaped negative electrode 12, the separator 15 into which a non-aqueous electrolyte is injected, the disc-shaped positive electrode 11, and spacer plates 17 and 18 made of stainless steel or aluminum are arranged in this order. In a stacked state, it is housed between a positive electrode can 13 (hereinafter, also referred to as a “battery can”) and a sealing plate 14 (hereinafter, also referred to as a “battery can lid”). The positive electrode can 13 and the sealing plate 14 are caulked and sealed via a gasket 16.
In this example, the non-aqueous electrolyte of the present disclosure is used as the non-aqueous electrolyte injected into the separator 15.

Note that the lithium secondary battery of the present disclosure is obtained by charging and discharging a lithium secondary battery (a lithium secondary battery before charging and discharging) including a negative electrode, a positive electrode, and the nonaqueous electrolyte of the present disclosure. Lithium secondary battery may be used.
That is, the lithium secondary battery of the present disclosure is, first, a negative electrode, a positive electrode, the non-aqueous electrolyte of the present disclosure, to prepare a lithium secondary battery before charging and discharging, and then, before this charging and discharging A lithium secondary battery (charged / discharged lithium secondary battery) manufactured by charging / discharging a lithium secondary battery once or more may be used.

  The use of the lithium secondary battery of the present disclosure is not particularly limited, and can be used for various known uses. For example, notebook computers, mobile computers, mobile phones, headphone stereos, video movies, LCD TVs, handy cleaners, electronic organizers, calculators, radios, backup power supplies, motors, automobiles, electric vehicles, motorcycles, electric motorcycles, bicycles, electric vehicles It can be widely used for small portable devices and large devices such as bicycles, lighting equipment, game machines, watches, power tools, cameras and the like.

Hereinafter, examples of the present disclosure will be described, but the present disclosure is not limited to the following examples.
In the following, “addition amount” means the content based on the total amount of the finally obtained non-aqueous electrolyte, and “wt%” means mass%.

[Example 1]
A coin-type battery (test battery) as a lithium secondary battery was manufactured in the following procedure.

<Preparation of negative electrode>
Amorphous natural graphite (97 parts by mass), carboxymethylcellulose (1 part by mass) and SBR latex (2 parts by mass) were kneaded with an aqueous solvent to prepare a paste-like negative electrode mixture slurry.
Next, the negative electrode mixture slurry was applied to a 10 μm-thick strip-shaped copper foil negative electrode current collector, dried, and then compressed by a roll press to form a sheet-shaped negative electrode comprising the negative electrode current collector and the negative electrode active material layer. I got At this time, the coating density of the negative electrode active material layer was 12 mg / cm ² , and the packing density was 1.5 g / mL.

<Preparation of positive electrode>
LiNi _0.5 Mn _0.3 Co _0.2 O ₂ (90 parts by mass), acetylene black (5 parts by mass), and polyvinylidene fluoride (5 parts by mass) are kneaded using N-methylpyrrolidinone as a solvent to form a paste. Was prepared.
Next, this positive electrode mixture slurry is applied to a 20 μm-thick strip-shaped aluminum foil positive electrode current collector, dried, and then compressed by a roll press to form a sheet-shaped positive electrode comprising a positive electrode current collector and a positive electrode active material layer. I got At this time, the coating density of the positive electrode active material layer was 22 mg / cm ² , and the packing density was 2.5 g / mL.

<Preparation of non-aqueous electrolyte>
Ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and 1,2-dimethoxyethane (DME) as non-aqueous solvents in a ratio of 30: 10: 30: 30 (vol%), respectively. To obtain a mixed solvent.
In a mixed solvent obtained, a LiPF ₆ as an electrolyte, the concentration of LiPF ₆ in the final non-aqueous electrolyte solution obtained was dissolved at a 1.0 mol / L.
The following compound (S1-1) (a specific example of the compound represented by the formula (S1)) (addition amount: 0.5% by mass) was added as an additive S to the solution obtained above, and the mixture was subjected to non-aqueous electrolysis. A liquid was obtained.

<Preparation of coin battery>
The above-mentioned negative electrode was punched into a disk shape with a diameter of 14 mm and the above-mentioned positive electrode with a diameter of 13 mm, to obtain a coin-shaped negative electrode and a coin-shaped positive electrode, respectively. Further, a microporous polyethylene film having a thickness of 20 μm was punched into a disk having a diameter of 17 mm to obtain a separator.
The obtained coin-shaped negative electrode, separator, and coin-shaped positive electrode are laminated in this order in a stainless steel battery can (2032 size), and then, 20 μL of a non-aqueous electrolyte is injected into the battery can. The separator, the positive electrode and the negative electrode were impregnated.
Next, an aluminum plate (thickness: 1.2 mm, diameter: 16 mm) and a spring were placed on the positive electrode, and the battery can was sealed by caulking the battery can lid via a polypropylene gasket.
As described above, a coin-type battery (that is, a coin-type lithium secondary battery) having a configuration shown in FIG. 3 having a diameter of 20 mm and a height of 3.2 mm was obtained.

<Evaluation of battery resistance>
The obtained coin-type battery was subjected to conditioning and aging in this order, and the aged coin-type battery was evaluated for battery resistance before and after high-temperature storage.
Here, “conditioning” means that the coin-type battery is repeatedly charged and discharged three times between 2.75 V and 4.2 V at 25 ° C. in a thermostat.
“Aging” means an operation of storing the conditioned coin-type battery at 60 ° C. for 72 hours in a state of 100% SOC (State of Charge).
The state of 100% SOC in this embodiment corresponds to a state where the battery is charged at a charging voltage of 4.25V.
The term “high-temperature storage” refers to an operation of storing an aged coin-type battery at 60 ° C. for 72 hours under an SOC of 100%.
Hereinafter, the battery resistance was measured under each of two temperature conditions of 25 ° C. and −20 ° C.

(Measurement of battery resistance before high temperature storage)
The SOC (State of Charge) of the coin-type battery after aging was adjusted to 80%, and then the battery resistance (DC resistance) of the coin-type battery before storage at high temperature was measured by the following method.
Using a coin-type battery adjusted to the above-mentioned SOC of 80%, CC10s discharge at a discharge rate of 0.2C, pause for 300 seconds, CC10s discharge at a discharge rate of 1C, pause for 300 seconds, CC10s discharge at a discharge rate of 2C, A pause of 300 seconds and a CC10s discharge at a discharge rate of 5C were performed in this order.
In addition, CC10s discharge means discharging at a constant current (Constant Current) for 10 seconds.
The DC resistance was determined based on the relationship between each discharge rate and the voltage at 10 seconds after the start of the discharge at each discharge rate, and the obtained DC resistance (Ω) was calculated as the battery resistance before storage of the coin-type battery at a high temperature (Ω). Ω).
Table 1 shows the results.

(Measurement of battery resistance after high temperature storage)
The coin-type battery whose battery resistance was measured before the high-temperature storage was CC-CV charged at 4.25 V at a charging rate of 0.2 C at 25 ° C. to a state of SOC 100%, and stored at this temperature at a high temperature (that is, 60 ° C.). For 72 hours). Here, the CC-CV charging means a constant current-constant voltage.
The SOC of the coin-type battery after high-temperature storage was adjusted to 80%, and then the battery resistance (Ω) of the coin-type battery after high-temperature storage was measured by the same method as the measurement of the battery resistance before high-temperature storage.
Table 1 shows the results.

[Examples 2 to 7]
The same operation as in Example 1 was performed except that the type of the additive S was changed as shown in Table 1.
Table 1 shows the results.
The additive S used in Examples 2 to 7 is as follows.

[Comparative Example 1]
The same operation as in Example 1 was performed except that the additive S was not contained in the non-aqueous electrolyte. Table 1 shows the results.
In Table 1, "-" means that the additive was not contained.

  As shown in Table 1, in Examples 1 to 7 containing the non-aqueous solvent containing DME and the additive S, comparison was made with Comparative Example 1 containing the non-aqueous solvent containing DME and not containing the additive S. As a result, the battery resistance before high-temperature storage and the battery resistance after high-temperature storage were reduced.

<Evaluation of gas generation>
Laminated batteries were produced using the non-aqueous electrolytes in Comparative Example 1 and Examples 1 to 4, and gas generation was evaluated using the obtained laminated batteries.
The details will be described below.

(Preparation of negative electrode piece)
The negative electrode mixture slurry prepared in Example 1 was applied to one surface of a 10 μm-thick strip-shaped copper foil-made negative electrode current collector, dried, and then compressed by a roll press to remove the negative electrode current collector and the negative electrode active material layer. Thus, a sheet-like negative electrode was obtained.
Two negative electrode pieces of 40 mm × 60 mm were cut out from the obtained sheet-shaped negative electrode.
A nickel tab was ultrasonically welded to each negative electrode piece.

(Preparation of positive electrode piece)
The positive electrode mixture slurry prepared in Example 1 was applied to both sides of a positive electrode current collector of a 20 μm-thick strip-shaped aluminum foil, dried, and then compressed by a roll press to form a positive electrode current collector and a positive electrode active material layer. A positive electrode in the form of a sheet was obtained.
From the obtained sheet-like positive electrode, one positive electrode piece of 40 mm × 40 mm was cut out.
An aluminum tab was ultrasonically welded to the positive electrode piece.

(Separator)
A separator having a size of 60 mm × 110 mm was cut out from a microporous polyethylene film having a thickness of 20 μm.

(Production of laminated battery)
The separator was bent at the center in the longitudinal direction to sandwich the positive electrode piece to obtain a laminate 1 having a separator / positive electrode piece / separator laminated structure.
The obtained laminate 1 was sandwiched between two pieces of negative electrode to obtain a laminate 2 having a laminated structure of negative electrode piece / separator / positive electrode piece / separator / negative electrode piece.
The obtained laminated body 2 was accommodated in a laminate exterior body, and three sides of the laminate exterior body were heat-sealed.
Next, 1 g of the nonaqueous electrolytic solution of Comparative Example 1 or any of Examples 1 to 4 was injected into the laminate exterior body from one side of the laminate exterior body that was not thermally fused, and a positive electrode piece, a negative electrode piece, And the separator was impregnated. Next, the laminate exterior body was sealed by heat-sealing one side not heat-sealed.
Thus, a laminated battery was obtained.

(Measurement of gas generation amount)
The specific gravity of the laminated battery in the air and the specific gravity of the laminated battery in water were measured with a specific gravity measuring device (SGM-300P, manufactured by Shimadzu Corporation).
Based on the obtained results, the gas generation amount (cm ³ ) was determined using Archimedes' principle.

FIG. 4 is a graph showing the gas generation amount (cm ³ ) when the nonaqueous electrolytes of Comparative Example 1 and Examples 1 to 4 were used.
As shown in FIG. 4, when the non-aqueous electrolytes of Examples 1 to 4 were used, the amount of gas generation was significantly reduced as compared with the case where the non-aqueous electrolyte of Comparative Example 1 was used. Was.
Thereby, as the additive S in the nonaqueous electrolyte, the compound represented by the formula (S1) (Examples 1 and 2), the compound represented by the formula (S2) (Example 3), and the compound represented by the formula (S4) )) (Example 4), it was found that gas generation due to DME was significantly suppressed.

DESCRIPTION OF SYMBOLS 1 Laminate exterior body 2 Positive electrode terminal 3 Negative electrode terminal 4 Insulating seal 5 Positive electrode plate 6 Negative electrode plate 7, 8 Separator 11 Positive electrode 12 Negative electrode 13 Positive electrode can 14 Sealing plate 15 Separator 16 Gasket 17, 18 Spacer plate

Claims (9)

A non-aqueous solvent containing 1,2-dimethoxyethane,
An electrolyte;
A compound represented by the following formula (S1), a compound represented by the following formula (S2), a compound represented by the following formula (S3), a compound represented by the following formula (S4), and a compound represented by the following formula (S5) And at least one additive S selected from the group consisting of compounds represented by
Non-aqueous electrolyte solution for batteries containing.

[In the formula (S1), R ^{11 to} R ¹⁴ are each independently a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a group represented by the formula (1a), or a formula (1b) Represents a group. In the formulas (1a) and (1b), * represents a bonding position.
In the formula (S2), R ^{21 to} R ²⁴ each independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.
In Formula (S3), R ^{31 to} R ³⁶ each independently represent a hydrogen atom, a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.
In the formula (S4), R ⁴¹ represents a fluorine atom, an alkoxy group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms.
In the formula (S5), R ⁵¹ represents a fluorine atom, a hydrocarbon group having 1 to 6 carbon atoms, or a fluorinated hydrocarbon group having 1 to 6 carbon atoms. ]   2. The non-aqueous electrolyte for a battery according to claim 1, wherein the content of the 1,2-dimethoxyethane is 10% by volume to 40% by volume based on the total amount of the non-aqueous solvent.   The additive S is at least one selected from the group consisting of a compound represented by the formula (S1), a compound represented by the formula (S2), and a compound represented by the formula (S3). The non-aqueous electrolytic solution for a battery according to claim 1, wherein the electrolytic solution comprises:   The non-aqueous electrolytic solution for a battery according to any one of claims 1 to 3, wherein the additive S includes at least one selected from the group consisting of compounds represented by the formula (S1). In the formula (S1), the R ¹¹ is a group represented by the formula (1a) or a group represented by the formula (1b), and each of R ¹² to R ¹⁴ is independently hydrogen. The battery according to any one of claims 1 to 4, which is an atom, a hydrocarbon group having 1 to 6 carbon atoms, a group represented by the formula (1a), or a group represented by the formula (1b). For non-aqueous electrolyte.   The non-aqueous solution for a battery according to any one of claims 1 to 5, wherein the content of the additive S is 0.001% by mass to 10% by mass with respect to the total amount of the non-aqueous electrolytic solution for a battery. Electrolyte.   The non-aqueous electrolyte for a battery according to any one of claims 1 to 6, wherein the non-aqueous solvent further includes a cyclic carbonate compound and a chain carbonate compound. A positive electrode,
Lithium metal, lithium-containing alloy, metal or alloy capable of being alloyed with lithium, oxide capable of doping / dedoping lithium ion, transition metal nitride capable of doping / dedoping lithium ion, and lithium A negative electrode containing, as a negative electrode active material, at least one selected from the group consisting of carbon materials capable of doping and undoping ions;
The non-aqueous electrolyte for a battery according to any one of claims 1 to 7,
Including lithium secondary batteries.   A lithium secondary battery obtained by charging and discharging the lithium secondary battery according to claim 8.