JP6915964B2 - Non-aqueous electrolyte for lithium-ion secondary batteries - Google Patents

Description

The present invention relates to a non-aqueous electrolyte solution for a power storage device such as a lithium ion secondary battery and a power storage device.

In recent years, with the spread of various portable electronic devices such as portable electronic terminals represented by mobile phones, smartphones, notebook computers, etc., secondary batteries play an important role as their power sources. Examples of these secondary batteries include lead storage batteries, aqueous batteries such as nickel-cadmium batteries, and non-aqueous electrolyte batteries. Among them, positive electrode and negative electrodes capable of storing and discharging lithium and the like and non-aqueous electrolyte batteries. The non-aqueous electrolyte secondary battery composed of the above has various advantages over other secondary batteries in terms of high voltage, high energy density, excellent safety, environmental problems, and the like. ..

As the non-aqueous electrolyte secondary battery currently in practical use, for example, a composite oxide of lithium and a transition metal is used as the positive electrode active material, and a material capable of doping and dedoping lithium is used as the negative electrode active material. A lithium ion secondary battery can be mentioned. In the negative electrode active material of a lithium ion secondary battery, a carbon material can be mentioned as a material having excellent cycle characteristics. Among carbon materials, graphite material is expected as a material that can improve the energy density per unit volume.

Further, in order to improve the characteristics of the lithium ion secondary battery, it is required to improve not only the characteristics of the negative electrode / positive electrode but also the characteristics of the non-aqueous electrolytic solution responsible for the transfer of lithium ions. As such a non-aqueous electrolyte solution, a lithium salt such as _{LiBF 4} , LiPF ₆ , LiClO ₄ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ CF ₂ CF ₃ ) _{2 was mixed with an aprotic organic solvent.} A non-aqueous solution is used (Non-Patent Document 1). Carbonates are known as typical examples of aprotic organic solvents, and the use of various carbonate compounds such as ethylene carbonate, propylene carbonate, and dimethyl carbonate has been proposed (Patent Documents 1 and 2).
On the other hand, as the electrolyte of the non-aqueous electrolyte solution, the non-aqueous electrolyte solution in which the LiBF ₄ and LiPF ₆ are dissolved has a high conductivity representing the transfer of lithium ions and a high oxidative decomposition voltage of the _{LiBF 4} and LiPF _6. Therefore, it is known to be stable at high voltage, which contributes to bring out the characteristics of high voltage and high energy density of lithium ion secondary batteries.

On the other hand, when a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery is used as each power source, the electrical resistance of the non-aqueous electrolyte is reduced to increase the conductivity of lithium ions. There is a demand for a long life that suppresses a decrease in battery capacity and maintains a high capacity even after repeated charging and discharging, so-called cycle characteristics are enhanced.
In order to achieve such an object, various proposals have been made conventionally for the non-aqueous electrolyte solution to specify the structure of the lithium salt which is an electrolyte and to add a specific compound. For example, in Patent Document 3, a vinyl sulfonic derivative having a specific structure is added to a non-aqueous electrolytic solution, and in Patent Document 4, a lithium salt other than a difunctional acid lithium salt having a specific structure is used. Therefore, it is known to add a lithium salt having no boron atom.
However, the conventional non-aqueous electrolytic solution is not always sufficiently satisfactory in terms of cost, and the non-aqueous electrolytic solution for a power storage device is required to be further improved for that purpose.

Japanese Unexamined Patent Publication No. 4-184872 Japanese Unexamined Patent Publication No. 10-27625 Japanese Unexamined Patent Publication No. 11-329494 Japanese Unexamined Patent Publication No. 2014-22334

The present invention enhances the solubility of the electrolyte in the non-aqueous electrolyte solution, reduces the electrical resistance of the non-aqueous electrolyte solution, and maintains a high capacity even after repeated charging and discharging a large number of times, a so-called cycle. An object of the present invention is to provide a non-aqueous electrolyte solution for a power storage device such as a lithium ion secondary battery having improved characteristics, and a power storage device using the non-water electrolyte solution.

As a result of conducting various research studies in order to achieve the above object, the present inventors have arrived at the present invention whose gist is as follows.
(1) A non-aqueous electrolytic solution for a lithium ion secondary battery in which the positive electrode active material contains a lithium-containing transition metal composite oxide and the negative electrode active material contains a carbon material (excluding silicon and tin).
Aqueous Ri Na by dissolving an electrolyte in a solvent, before Symbol electrolyte is lithium salt dissolved in the nonaqueous solvent, and boric acid compound consisting of tetraborate or a salt thereof, or a metaborate or a salt thereof, Non-water for a lithium ion secondary battery, which contains a sulfonic acid compound composed of a cyclic or chain disulfonate or an ester having two sulfonic acid groups represented by the following formula (1). Electrolyte.
M _1- O- (O =) ₂ SC (R ₁ R ₂ ) -S (= O) _2- O-M ₂ (1)
(In the formula (1), R ₁ and R ₂ have a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 2 to 6 carbon atoms, or an alkenyl group having 1 to 6 carbon atoms. Alkoxy groups having. M ₁ and M ₂ are alkali metals or alkyl groups having 1 to 6 carbon atoms.)

(2) in the nonaqueous electrolytic solution, wherein the boric acid compound contained 0.01 wt%, and lithium ions according to the sulfonic acid compound in the (1) containing 0.01 to 3 wt% Non-aqueous electrolyte for secondary batteries.
(3) A lithium ion secondary battery comprising the non-aqueous electrolytic solution according to (1) or (2) above.

( 4 ) The lithium ion secondary battery according to (3 ) above, wherein a layered rock salt structure type lithium-containing transition metal composite compound represented by the following formula (2) is used as a positive electrode active material.
_{Li (Ni x Co y Mn z} ) O 2 (2)
(In the formula, x is 0.2 ≦ x ≦ 0.9, y is 0 ≦ y ≦ 0.5, and z is 0 ≦ z ≦ 0.9.)
( 5 ) The lithium ion secondary battery according to (4 ) above, wherein x is larger than 0.5 and y is smaller than 0.3 in the above formula (2).

The non-aqueous electrolyte solution according to the present invention not only enhances the solubility of the lithium electrolyte in the non-aqueous electrolyte solution and lowers the electrical resistance of the non-aqueous electrolyte solution, but also maintains a high capacity even after repeated charging and discharging. It enhances the so-called cycle characteristics. Therefore, a non-aqueous electrolyte solution for a power storage device such as a lithium ion secondary battery having good initial characteristics and excellent cycle characteristics is provided.

Hereinafter, the non-aqueous electrolytic solution of the present invention and the power storage device using the same will be described in detail.
<Non-aqueous solvent>
Various non-aqueous solvents can be used as the non-aqueous solvent used in the non-aqueous electrolytic solution of the present invention. For example, an aprotic polar solvent is preferred. Specific examples thereof include ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, trifluoromethylethylene carbonate, and fluoroethylene carbonate. And cyclic carbonates such as 4,5-difluoroethylene carbonate; lactones such as γ petitrolactone and γ-valerolactone; cyclic sulfones such as sulfolane; cyclic ethers such as tetrahydrofuran and dioxane; ethylmethyl carbonate, dimethyl carbonate, diethyl carbonate, methylpropyl carbonate. , Methylisoprovir carbonate, dipropyl carbonate, methylbutyl carbonate, dibutyl carbonate, ethylpropyl carbonate and chain carbonates such as methyltrifluoroethyl carbonate; nitriles such as acetonitrile; chain ethers such as dimethyl ether; chains such as methyl propionate. Cyril carboxylic acid ester; Chain glycol ether such as dimethoxyethane; 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (CF ₂ HCF ₂ CH ₂ OCF ₂ CF ₂ H) ), 1,1,2,2-tetrafluoroethyl-2,2,3,3,3-pentafluoropropyl ether (CF ₃ CF ₂ CH ₂ OCF ₂ CF ₂ H), ethoxy-2,2,2- Examples thereof include fluorine-substituted ethers such as trifluoroethoxy-ethane (CF ₃ CH _{2 OCH 2} CH ₂ OCH ₂ CH _3). These can be used alone or in combination of two or more.

As the non-aqueous solvent, it is more preferable to use a carbonate-based solvent such as a cyclic carbonate or a chain carbonate from the viewpoint of ionic conductivity. It is more preferable to use a combination of cyclic carbonate and chain carbonate as the carbonate solvent. Among the above, the cyclic carbonate is preferably ethylene carbonate, propylene carbonate or fluoroethylene carbonate. Among the above, ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate are preferable as the chain carbonate. When a carbonate solvent is used, another non-aqueous solvent such as a nitrile compound or a sulfone solvent can be further added, if necessary, from the viewpoint of improving the physical characteristics of the battery.

In the present invention, as the non-aqueous solvent, it is particularly preferable to contain a chain carbonate ester, a saturated cyclic carbonate, and an unsaturated cyclic carbonate. When these three types of carbonic acid esters are contained, it is particularly preferable as long as the effects of the present invention are exhibited. The non-aqueous solvent used in the present invention contains 30 to 80% by mass and 10 to 50% by mass, respectively, of the chain carbonate, the saturated cyclic carbonate, and the unsaturated cyclic carbonate in the non-aqueous electrolyte. And 0.01 to 5% by mass, and more preferably 50 to 70% by mass, 20 to 30% by mass, and 0.1 to 2% by mass, respectively.

When the chain carbonate is smaller than 30% by mass, the viscosity of the electrolytic solution increases, and in addition, it solidifies at a low temperature, so that sufficient characteristics cannot be obtained, and conversely, it is more than 80% by mass. If it is large, the dissociation / solubility of the lithium salt will decrease, and the ionic conductivity of the electrolytic solution will decrease. When the saturated cyclic carbonate is smaller than 10% by mass, the dissociation / solubility of the lithium salt is lowered, the ionic conductivity of the electrolytic solution is lowered, and conversely, when it is larger than 50% by mass, the electrolytic solution is used. In addition, the viscosity of the compound increases, and in addition, it solidifies at a low temperature, so that sufficient characteristics cannot be obtained.
Further, when the unsaturated cyclic carbonate is smaller than 0.01% by mass, a good film is not formed on the surface of the negative electrode, so that the cycle characteristics are deteriorated. On the contrary, when it is larger than 5% by mass, for example, When stored at a high temperature, the electrolytic solution tends to generate gas, and the pressure inside the battery rises, which is not preferable for practical use.

Examples of the chain carbonate used in the present invention include chain carbonates having a total carbon number of 3 to 9. Specifically, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propylisopropyl carbonate, di-n-butyl carbonate, di-t-butyl carbonate, n-butylisobutyl carbonate, n-Butyl-t-butyl carbonate, isobutyl-t-butyl carbonate, ethylmethyl carbonate, methyl-n-propyl carbonate, n-butylmethyl carbonate, isobutylmethyl carbonate, t-butylmethyl carbonate, ethyl-n-propyl carbonate, n-Butyl ethyl carbonate, isobutyl ethyl carbonate, t-butyl ethyl carbonate, n-butyl-n-propyl carbonate, isobutyl-n-propyl carbonate, t-butyl-n-propyl carbonate, n-butyl isopropyl carbonate, isobutyl isopropyl carbonate , T-Butylisopropylcarbonate and the like. Of these, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate are preferable, but are not particularly limited. Further, two or more kinds of these chain carbonic acid esters may be mixed.

Examples of the saturated cyclic carbonate used in the present invention include ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate and the like. Among these, ethylene carbonate, propylene carbonate, and fluoroethylene carbonate are more preferable, and by using propylene carbonate, a stable non-aqueous electrolytic solution can be provided in a wide temperature range. Two or more kinds of these saturated cyclic carbonates may be mixed.

Further, examples of the unsaturated cyclic carbonate used in the present invention include a vinylene carbonate derivative represented by the following general formula (I).

In the above general formula (I), R ₁ and R ₂ are alkyl groups which may independently contain a hydrogen atom, a halogen atom, or a halogen atom having 1 to 12 carbon atoms. Of these, _{hydrogen with R 1} and R ₂ (the compound of (I) is vinylene carbonate) is preferable.

Specific examples of the vinylene carbonate derivative include the following compounds. Vinylene carbonate, fluorovinylene carbonate, methylvinylene carbonate, fluoromethylvinylene carbonate, ethylvinylene carbonate, propylvinylene carbonate, butylvinylene carbonate, dimethylvinylene carbonate, diethylvinylene carbonate, dipropylvinylene carbonate, etc., but are limited to these. It's not a thing.

Among these compounds, vinylene carbonate is effective and cost-effective. The vinylene carbonate derivative is at least one kind, and may be used alone or in combination.
Further, as another unsaturated cyclic carbonate used in the present invention, alkenylethylene carbonate represented by the following general formula (II) can be mentioned.

In the above formula (II), R _{3 to} R ₆ each independently contain a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 12 carbon atoms, or a hydrocarbon group having 2 to 12 carbon atoms. There are 12 alkenyl groups, at least one of which is an alkenyl group having 2 to 12 carbon atoms. Among _{them, it is preferable that one of R 3 to} R ₆ is a vinyl group and the rest is hydrogen (the compound of (II) is 4-vinylethylene carbonate).

Specific examples of the alkenylethylene carbonate include compounds such as 4-vinylethylene carbonate, 4-vinyl-4-methylethylene carbonate, 4-vinyl-4-ethylethylene carbonate, and 4-vinyl-4-n-propylethylene carbonate. Can be mentioned.

The non-aqueous solvent used in the present invention may contain various other solvents in addition to the above-mentioned components. Examples of these other various solvents include cyclic carboxylic acid esters, chain esters having a total carbon number of 3 to 9, and chain ethers having a total carbon number of 3 to 6. These other various solvents are preferably contained in the non-aqueous electrolytic solution in an amount of 0.2 to 10% by mass, particularly preferably 0.5 to 5% by mass.

Examples of the cyclic carboxylic acid ester (lactone compound having a total carbon number of 3 to 9) include γ-butyrolactone, γ-valerolactone, γ-caprolactone, and ε-caprolactone. Of these, γ-butyrolactone and γ-valerolactone are more preferable, but are not particularly limited. Further, two or more kinds of these cyclic carboxylic acid esters may be mixed.

Examples of the chain ester having a total carbon number of 3 to 9 include methyl acetate, ethyl acetate, -n-propyl acetate, -isopropyl acetate, -n-butyl acetate, isobutyl acetate, -t-butyl acetate, and propionic acid. Examples thereof include methyl, ethyl propionate, -n-propyl propionate, -isopropyl propionate, -n-butyl propionate, isobutyl propionate, and -t-butyl propionate. Of these, ethyl acetate, methyl propionate, and ethyl propionate are preferable.

Examples of the chain ether having a total carbon number of 3 to 6 include dimethoxymethane, dimethoxyethane, diethoxymethane, diethoxyethane, ethoxymethoxymethane, and ethoxymethoxyethane. Of these, dimethoxyethane and diethoxyethane are more preferable.

Further, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, 4-methyldioxolane, N, N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene and the like can be used. ..

<Lithium salt>
A lithium salt is used as the solute of the non-aqueous electrolyte solution of the present invention. The lithium salt is not particularly limited as long as it can be dissolved in the above-mentioned non-aqueous solvent. Specific examples thereof are as follows.
(A) Inorganic lithium salt:
LiPF _6, LiAsF _6, inorganic fluoride salts LiBF ₄ or the _{like, LiClO 4, LiBrO 4, LiIO} 4, perhalogenate etc. like.
(B) Organolithium salt:
Organic sulfonates such as LiCF ₃ SO ₃ , perfluoro such as LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) Alkyl sulfonic acid imide salt, perfluoroalkyl sulfonic acid methide salt such as _{LiC (CF 3} SO ₂ ) _{3 , LiPF (CF 3} ) ₅ , LiPF ₂ (CF ₃ ) ₄ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₂ ( C ₂ F ₅ ) ₄ , LiPF ₃ (C ₂ F ₅ ) ₃ , LiPF (n-C ₃ F ₇ ) ₅ , LiPF ₂ (n-C ₃ F ₇ ) ₄ , LiPF ₃ (n-C ₃ F ₇ ) ₃ , LiPF (iso-C ₃ F ₇ ) ₅ , LiPF ₂ (iso-C ₃ F ₇ ) ₄ , LiPF ₃ (iso-C ₃ F ₇ ) ₃ , LiB (CF ₃ ) ₄ , LiBF (CF ₃ ) ₃ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₃ (CF ₃ ), LiB (C ₂ F ₅ ) ₄ , LiBF (C ₂ F ₅ ) ₃ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₃ (C ₂ F) ₅ ), LiB (n-C ₃ F ₇ ) ₄ , LiBF (n-C ₃ F ₇ ) ₃ , LiBF ₂ (n-C ₃ F ₇ ) ₂ , LiBF ₃ (n-C ₃ F ₇ ), LiB ( Some fluorine such as iso-C ₃ F ₇ ) ₄ , LiBF (iso-C ₃ F ₇ ) ₃ , LiBF ₂ (iso-C ₃ F ₇ ) ₂ , LiBF ₃ (iso-C ₃ F _{7) is added.} Examples thereof include an inorganic fluoride salt fluorophosphate substituted with a fluoroalkyl group and a fluorine-containing organic lithium salt of perfluoroalkyl.

In the present invention, among the above, LiPF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ ) , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) is more preferred. Further, two or more kinds of these lithium salts may be mixed.

The concentration of the lithium salt, which is the solute of the non-aqueous electrolyte solution of the present invention, is preferably 0.5 to 3 mol / liter, and particularly preferably 0.7 to 2 mol / liter. If this concentration is too low, the ionic conductivity of the non-aqueous electrolyte solution will be insufficient due to an absolute lack of concentration, and if the concentration is too high, the ionic conductivity will decrease due to an increase in viscosity, and precipitation at low temperatures will occur. Since it is likely to occur and causes problems, the performance of the non-aqueous electrolyte battery is deteriorated, which is not preferable.

<Additives>
To the non-aqueous electrolytic solution of the present invention, a boric acid compound composed of tetraboric acid or a salt thereof, or metaboric acid or a salt thereof, and a sulfonate or ester or a sulfonic acid anhydride are added.
<Boric acid compound>
As the boric acid compound, a boric acid compound composed of tetraboric acid (H ₂ B ₄ O ₆ ) or a salt thereof, or metaboric acid (HBO ₂ ) or a salt thereof is coated. The tetraboric acid and metaboric acid may be anhydrous, anhydrate to polyhydrate, and their crystal forms may be orthorhombic, monoclinic, or cubic. Also, t may have a multimer term in which boric acid molecules are associated, such as a trimer of metaboric acid.

As the salt of tetraborate and the salt of metaboric acid, a compound dissolved in a non-aqueous solvent used in the non-aqueous electrolyte solution of the present invention is preferable. The type of salt does not matter as long as it is soluble. For example, alkali metal salts such as lithium, sodium and potassium; polyvalent metal salts such as calcium, magnesium, manganese and iron; ammonium salts such as tetramethylammonium, tetraethylammonium, tetrapropylammonium and tetrabutylammonium; dimethylimidazolium, Imidazolium salts such as dimethylimidazolium and ethylmethylimidazolium; pyridium salts such as methylpyridium and ethylpyridium can be used. Among the above, alkali metal salts such as lithium, sodium and potassium are preferable, and lithium salts are particularly preferable.

Preferred specific examples of tetraboric acid or a salt thereof, or metaboric acid or a salt thereof, include lithium metaborate, magnesium metaborate, calcium metaborate, barium metaborate, lithium tetraborate, magnesium tetraborate, calcium tetraborate. , Barium borate, tetramethylammonium metaborate, tetramethylammonium tetraborate, etc. Of these, lithium metaborate, magnesium metaborate, barium metaborate, lithium tetraborate, magnesium tetraborate, barium tetraborate and the like are preferable.

<Sulfonate or ester or sulfonic acid anhydride>
The sulfonate or ester or sulfonic acid anhydride in the present invention may be either chain or cyclic, and the following are exemplified.
As the sulfonate, a compound dissolved in a non-aqueous solvent used in the non-aqueous electrolyte solution of the present invention is preferable. The type of salt does not matter as long as it is soluble. For example, alkali metal salts such as lithium, sodium and potassium; polyvalent metal salts such as calcium, magnesium, manganese and iron; ammonium salts such as tetramethylammonium, tetraethylammonium, tetrapropylammonium and tetrabutylammonium; dimethylimidazolium, Imidazolium salts such as dimethylimidazolium and ethylmethylimidazolium; pyridium salts such as methylpyridium and ethylpyridium can be used. Among them, alkali metal salts such as lithium, sodium and potassium are preferable, and lithium salts are particularly preferable.

Examples of the sulfonate include lithium methanesulfonate, lithium trifluoromethanesulfonate, lithium hexafluoromethanesulfonate, lithium 1,3-propanesulfonate, lithium 1,4-butanesulfonate, and dilithium 1,1-methanedisulfonate. , 1,2-Dilithium ethanedisulfonate, Dilithium 1,3-propanedisulfonate, Dilithium 1-methyl-1,3-propanedisulfonate, Dilithium 1,4-butanedisulfonate, Dilithium methoxymethanedisulfonate, ethoxymethanedisulfone Dilithium acid, disodium 1,1-methanedisulfonate, disodium 1,2-ethanedisulfonate, disodium 1,3-propanedisulfonate, disodium 1,4-butanedisulfonate, disodium methoxymethanedisulfonate, Disodium ethoxymethanedisulfonate, magnesium 1,1-methanedisulfonate, magnesium 1,2-ethanedisulfonate, magnesium 1,3-propanedisulfonate, magnesium 1,4-butanedisulfonate, aniline-2,5-disulfone Examples thereof include lithium acid and lithium 4,4'-biphenyldisulfonate. Among them, dilithium 1,1-methanedisulfonate, dilithium 1,2-ethanedisulfonate, dilithium 1,3-propanedisulfonate, dilithium 1,4-butanedisulfonate, dilithium methoxymethanedisulfonate, dilithium ethoxymethanedisulfonate , Or dilithium 1,1-prope-2-yldisulfonate is preferred.

Examples of the sulfonic acid ester include 1,3-propanesulton, propensulton, 1,4-butanesulton, methyl methanesulfonate, ethyl methanesulfonate, dimethyl methanedisulfonate, diethyl methanedisulfonate, dipropyl methanedisulfonate, and methanedisulfonic acid. Bis (trifluoromethyl), bis (trimethylsilyl) methanedisulfonate, methylenemethanedisulfonic acid, ethylene methanedisulfonate, propylene methanedisulfonate, methylene ethylenedisulfonate, ethylene ethylenedisulfonate, dimethyl ethanedisulfonate, diethyl ethanedisulfonate, Bis ethanedisulfonate (trifluoromethyl), bis ethanedisulfonate (trimethylsilyl), dimethyl propanedisulfonate, diethyl propanedisulfonate, methylene propanedisulfonate, ethylene propanedisulfonate, dimethyl 1,5-naphthalenedisulfonate, butanedisulfonic acid Examples thereof include dimethyl and diethyl butanedisulfonate.
Among them, dimethyl methanedisulfonate, diethyl methanedisulfonate, bis (trimethylsilyl) methanedisulfonate, methylenemethanedisulfonic acid, ethylene methanedisulfonate, methylene ethylenedisulfonate, bis (trimethylsilyl) ethanedisulfonate, methylene propanodisulfonate, ethane. Dimethyl disulfonate, diethyl ethanedisulfonate, or dimethyl butanedisulfonate is preferred.

Examples of the sulfonic acid anhydride include trifluoromethanesulfonic anhydride, 1,2-ethanedisulfonic anhydride, 1,3-propanedisulfonic anhydride, 1,4-butanedisulfonic anhydride, and 1,2-benzenedisulfone. Acid anhydride, tetrafluoro-1,2-ethanedisulfonic acid anhydride, hexafluoro-1,3-propanedisulfonic acid anhydride, octafluoro-1,4-butanedisulfonic acid anhydride, 3-fluoro-1,2 Examples thereof include −benzenedisulfonic anhydride, 4-fluoro-1,2-benzenedisulfonic anhydride, 3,4,5,6-tetrafluoro-1,2-benzenedisulfonic anhydride and the like.
Among them, 1,2-ethanedisulfonic anhydride, 1,3-propanedisulfonic anhydride, 1,4-butanedisulfonic anhydride, tetrafluoro-1,2-ethanedisulfonic anhydride, hexafluoro-1 , 3-Propane disulfonic anhydride or octafluoro-1,4-butane disulfonic anhydride is preferred.

In the present invention, cyclic or chain disulfonates, esters or anhydrides having two sulfonic acid groups represented by the following formula (1) are particularly preferable.
M _1- O- (O =) ₂ SC (R ₁ R ₂ ) -S (= O) _2- O-M ₂ (1)
In the above formula (1), R ₁ and R ₂ are an alkyl group, an alkenyl group or an alkoxy group having a hydrogen atom, a halogen atom and a carbon number of 1 to 6, preferably 1 to 4. R ₁ and R ₂ may be combined to form a ring. M ₁ and M ₂ are alkali metals or alkyl groups having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The alkyl group, alkenyl group, and alkoxy group may be linear or branched. Lithium is preferable as the alkali metal. M ₁ and M ₂ may be combined to form a ring.

Examples of the cyclic or chain disulfonate ester or salt having two sulfonic acid groups having the above formula (1) include the sulfonates, sulfonic acid esters, and sulfonic acid anhydrides exemplified above. , A compound satisfying the formula (1) can be mentioned.
Among them, dilithium 1,1-methanedisulfonate, dilithium 1,2-ethanedisulfonate, dilithium 1,3-propanedisulfonate, dilithium 1,4-butanedisulfonate, dilithium methoxymethanedisulfonate, dilithium ethoxymethanedisulfonate , 1,1-Prope-2-Dilithium yldisulfonate and other sulfonates, dimethyl methanedisulfonate, diethyl methanedisulfonate, bis (trimethylsilyl) methanedisulfonate, methylenemethanedisulfonic acid, ethylene methanedisulfonate, ethylenedisulfonic acid Sulphonic acid esters such as methylene, bis (trimethylsilyl) ethanedisulfonate, methylene propanodisulfonate, dimethyl ethanedisulfonate, diethyl ethanedisulfonate, dimethyl butanedisulfonate, 1,2-ethanedisulfonic acid anhydride, 1,3- Propanedisulfonic acid anhydride, 1,4-butanedisulfonic acid anhydride, tetrafluoro-1,2-ethanedisulfonic acid anhydride, hexafluoro-1,3-propanedisulfonic acid anhydride, octafluoro-1,4-butane Sulfonic acid anhydrides such as disulfonic acid anhydride are preferred.

The content of the specific boric acid compound in the non-aqueous electrolytic solution of the present invention is preferably 0.0001 to 10% by mass, more preferably 0.001 to 2% by mass, and particularly preferably 0.01 to 1% by mass. be. If the content is less than 0.0001% by mass, the resistance reducing effect is reduced. On the other hand, if it exceeds 10% by mass, the film resistance becomes high and the life performance deteriorates, which is not preferable.
On the other hand, the content of the sulfonate or ester or sulfonic acid anhydride is preferably 0.0001 to 10% by mass, more preferably 0.01 to 3% by mass, and particularly preferably 0.01 to 2% by mass. .. If the content is less than 0.0001% by mass, the resistance reducing effect is reduced. If it exceeds 10% by mass, the film resistance becomes high and the life performance deteriorates, which is not preferable.

<Additional additives>
The non-aqueous electrolytic solution of the present invention may contain additional additives in addition to the above-mentioned specific additives for the purpose of improving the life performance and resistance performance of the power storage device. As a further additive, one or more compounds selected from the group consisting of sulfur-containing compounds (excluding the above-mentioned sulfonates or esters or sulfonic acid anhydrides), carboxylic acid compounds, and boron-containing compounds can be used.
Examples of the sulfur-containing compound include ethylene sulfite, hexahydrobenzo [1,3,2] dioxathiolan-2-oxide (also referred to as 1,2-cyclohexanediol cyclic sulfite), and 5-vinyl-hexahydro 1,3. 2-benzodioxathiol-2-oxide, 1,4-butanediol dimethanesulfonate, 1,3-butanediol dimethanesulfonate, methylenemethanedisulfonic acid, ethylenemethanedisulfonic acid, N, N-dimethylmethanesulfonamide, Examples thereof include N, N-diethylmethanesulfonamide, divinylsulfone and 1,2-bis (vinylsulfonyl) methane.

Examples of the carboxylic acid compound include lithium oxalate, lithium malonate, lithium difluoromalonate, lithium succinate, lithium tetrafluorosuccinate, lithium adipate, lithium glutarate, lithium acetone dicarboxylic acid, lithium 2-oxobutyrate, and oxal. Lithium acetate, lithium 2-oxoglutarate, lithium acetoacetate, 3-oxocyclobutanecarboxylic acid, 3-oxocyclopentanecarboxylic acid, lithium 2-oxovalerate, lithium pyruvate, lithium glyoxylate, 3,3-dimethyl-2 -Lithium oxobutyrate, lithium 2-hydroxypropionate, lithium 2-methyllactate, lithium tartrate, lithium cyanoacetate, lithium 2-mercaptopropionate, methylenebis (thioglycolic acid) lithium thiodisuccinate, 3- (methylthio) propionic acid Included are lithium, lithium 3,3'-thiodipropionate, lithium dithiodiglycolate, lithium 2,2'-thiodiglycolate, lithium thiazolidine-2,4-dicarboxylate, or lithium acetylthioacetate.

Examples of the boron-containing compound include LiBF ₂ (C ₂ O ₄ ), LiB (C ₂ O ₄ ) ₂ , LiBF ₂ (CO ₂ CH ₂ CO ₂ ), LiB (CO ₂ CH ₂ CO _{2 ) 2} , and LiB (CO). ₂ CF ₂ CO ₂ ) ₂ , LiBF ₂ (CO ₂ CF ₂ CO ₂ ), LiBF ₃ (CO ₂ CH ₃ ), LiBF ₃ (CO ₂ CF ₃ ), LiBF ₂ (CO ₂ CH ₃ ) ₂ , LiBF ₂ ( CO ₂ CF ₃ ) ₂ , LiBF (CO ₂ CH ₃ ) ₃ , LiBF (CO ₂ CF ₃ ) ₃ , LiB (CO ₂ CH ₃ ) ₄ , LiB (CO ₂ CF ₃ ) ₄ , Li ₂ B ₂ O ₇ , Alternatively, Li ₂ B ₂ O ₄ can be mentioned.
As the above-mentioned additional additive, one kind of each may be used alone, or two or more kinds may be used in combination. When the non-aqueous electrolytic solution contains the above-mentioned additional additive, the content of the above-mentioned additional additive in the non-aqueous electrolytic solution is preferably 0.01 to 5% by mass, although it depends on the additive. Is more preferably 0.1 to 2% by mass.

<Power storage device>
The non-aqueous electrolyte solution of the present invention can be used in various power storage devices such as a lithium ion secondary battery, an electric double layer capacitor, and a hybrid battery in which one of the positive electrode or the negative electrode is a battery and the other is a double layer. The following describes a typical example of the lithium ion secondary battery.
The negative electrode active material constituting the negative electrode includes a carbon material capable of dope / dedope of lithium ions, metallic lithium, a lithium-containing alloy, or silicon, a silicon alloy, tin, which can be alloyed with lithium. Tin alloy, tin oxide capable of dope / removal of lithium ions, silicon oxide, transition metal oxide capable of dope / removal of lithium ions, dope / removal of lithium ions Either a transition metal nitrogen compound capable of dope, or a mixture thereof can be used. The negative electrode is generally configured such that a negative electrode active material is formed on a current collector such as a copper foil or an expanded metal. In order to improve the adhesiveness of the negative electrode active material to the current collector, for example, a polyvinylidene fluoride-based binder, a latex-based binder, or the like may be contained, and carbon black, amorphous whisker carbon, or the like may be added as a conductive auxiliary agent. You may use it.

As the carbon material constituting the negative electrode active material, for example, thermally decomposed carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphites, calcined organic polymer compound (phenol resin, furan resin, etc.) are suitable. (Coke), carbon fiber, activated carbon, etc. The carbon material may be graphitized. As the carbon material, a carbon material having a (002) plane spacing (d002) of 0.340 nm or less measured by an X-ray diffraction method is particularly preferable, ^{and graphite having a true density of 1.70 g / cm 3} or more or close to it. A highly crystalline carbon material having properties is desirable. When such a carbon material is used, the energy density of the non-aqueous electrolyte battery can be increased.

Further, a material containing boron in the carbon material, a material coated with a metal such as gold, platinum, silver, copper, Sn, Si, or a material coated with amorphous carbon can be used. These carbon materials may be used alone or in combination of two or more as appropriate.
In addition, silicon, silicon alloys, tin, tin alloys that can be alloyed with lithium, tin oxide that can dope / dedope of lithium ions, silicon oxide, and transition metals that can dope / dedope of lithium ions. When oxides are used, they are suitable materials because they have a higher theoretical capacity per weight than the above-mentioned carbonaceous materials.

On the other hand, the positive electrode active material constituting the positive electrode can be formed from various materials capable of charging and discharging. For example, lithium-containing transition metal oxides, lithium-containing transition metal composite oxides using one or more kinds of transition metals, transition metal oxides, transition metal sulfides, metal oxides, olivine-type metal lithium salts and the like can be mentioned.
In the present invention, as the positive electrode active material, a layered rock salt structure type lithium composite compound represented by the following formula (2) is preferable.
_{Li (Ni x Co y Mn z} ) O 2 (2)
However, in the formula (2), x is 0.2 ≦ x ≦ 0.9, y is 0 ≦ y ≦ 0.5, and z is 0 ≦ x ≦ 0.9.
Among them, x (Ni / Ni (Ni + Co + Mn)), which is the Ni content of the positive electrode active material, is preferably 0.2 to 0.8, more preferably 0.3 to 0.7, in terms of molar ratio. The Co content of the positive electrode active material, y (Co / (Ni + Co + Mn)), is preferably 0.1 to 0.5, more preferably 0.2 to 0.4, in terms of molar ratio. The Mn content of the positive electrode active material, z (, Mn / (Ni + Co + Mn)), is preferably 0.1 to 0.5, more preferably 0.2 to 0.4, in terms of molar ratio.
Preferred examples of such positive electrode active material are LiNi _6/10 Mn _4/10 O ₂ , LiNi _7/10 Mn _3/10 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _{5 /. 10} Co _2/10 Mn _3/10 O ₂ , LiNi _6/10 Co _2/10 Mn _2/10 O ₂ , LiNi _7/10 Co _1/10 Mn _2/10 O ₂ , LiNi _8/10 Co _1/10 Mn _1/10 O ₂ can be mentioned.

Further, another preferable positive electrode active material in the present invention is an olivine-type lithium composite compound represented by the following formula (3).
Li _x MPO ₄ (3)
However, in the formula (1), M is at least one element selected from the group consisting of Co, Ni, Mn and Fe, and has 0 <x ≦ 2, preferably 0.05 ≦ x ≦. 1.20 is preferred.
Preferred examples of such an olivine-type lithium composite compound include LiFePO ₄ , LiNiPO ₄ , LiMnPO _{4, and the} like.

Further, it is also possible to use a substance having a composition different from that of the main substance constituting the positive electrode active material attached to the surface of the positive electrode active material. Surface adhering substances include carbon, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide and other oxides; lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate. , Sulfates such as calcium sulfate and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate can be mentioned.
Further, the positive electrode is generally composed of a positive electrode active material formed on a current collector such as a foil made of aluminum, titanium or stainless steel, or an expanded metal. In order to improve the adhesiveness of the positive electrode active material to the current collector, for example, a polyvinylidene fluoride-based binder, carbon black, amorphous whisker, graphite, etc. may be contained to improve the electron conductivity in the positive electrode. ..

The separator is preferably a film that electrically insulates the positive electrode and the negative electrode and allows lithium ions to pass through, and for example, a porous film such as a microporous polymer film is used. As the microporous polymer film, a porous polyolefin film is particularly preferable, and more specifically, a porous polyethylene film, a porous polypropylene film, or a multilayer film of a porous polyethylene film and a polypropylene film is preferable. Further, a polymer electrolyte can be used as a separator. As the polymer electrolyte, for example, a polymer substance in which a lithium salt is dissolved, a polymer substance swollen with an electrolytic solution, and the like can be used, but the polymer electrolyte is not limited thereto.
The non-aqueous electrolyte solution of the present invention may be used for the purpose of swelling a polymer substance with the non-aqueous electrolyte solution to obtain a polymer electrolyte, or a separator in the form of a combination of a porous polyolefin film and a polymer electrolyte. May be impregnated with a non-aqueous electrolyte solution.
The shape of the lithium ion secondary battery using the non-aqueous electrolyte solution of the present invention is not particularly limited, and may be various shapes such as a cylindrical type, a square type, an aluminum laminated type, a coin type, and a button type. Can be done.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples, and modifications can be made within the scope of the present invention.

<Preparation of non-aqueous electrolyte 1-1>
LiPF6 as a lithium salt was added to a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and fluoroethylene carbonate (FEC) (volume mixing ratio: 30:68: 2) at a concentration of 1 mol / liter. , To prepare a non-aqueous electrolyte solution 1-1.

<Preparation of non-aqueous electrolyte solution 1-2 to 1-4>
LiPF6 as a lithium salt was added to a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and fluoroethylene carbonate (FEC) (volume mixing ratio: 30:68: 2) at a concentration of 1 mol / liter. , Lithium tetraborate was added in an amount of 0.1% by volume and dissolved.
Non-aqueous electrolytes 1-2 and 1- are dissolved by adding 1.0% by mass of propensulton, ethylenemethanedisulfonic acid, and 1,3-propanedisulfonic acid anhydride to the above solutions, respectively. 3, 1-4 were prepared.

<Preparation of non-aqueous electrolytes 2-1 to 2-3>
_{LiPF 6} as a lithium salt in a mixed solvent (volume mixing ratio of 30:68: 2) of ethylene carbonate (EC), ethylmethyl carbonate (EMC), and fluoroethylene carbonate (FEC) at a concentration of 1 mol / liter. In addition, 0.1% by volume of lithium tetraborate and 0.5% by volume of 1,3-propanedisulfonic anhydride were added and dissolved.
Non-aqueous by adding 0.5% by mass of dilithium 1,2-ethanedisulfonate, dilithium 1,3-propanedisulfonate, and dilithium 1,4-butanedisulfonate to the above solutions, respectively, to dissolve them. Electrolyte 2-1, 2-2, 2-3 were prepared.

<Examples 1 to 3>
<Preparation of positive electrode>
As the positive electrode active material, 91% by mass of the lithium-nickel-manganese-cobalt composite oxide powder having a Ni: Mn: Co ratio of 5: 3: 2, 5% by mass of polyvinylidene fluoride as a binder, and conductivity. N-Methylpyrrolidone is added to a positive electrode mixture made by mixing 4% by mass of acetylene black, which is an agent, to prepare a paste, which is applied to both sides of an aluminum foil current collector having a thickness of 18 μm, and a solvent is applied. After drying and removing, a positive electrode was prepared by rolling with a roll press.

<Manufacturing of negative electrode>
95.8% by mass of artificial graphite-forming carbon powder, 2.0% by mass of styrene-butadiene rubber (SBR) as a solvent, and 2.2% by mass of carboxymethyl cellulose aqueous solution are mixed, and water is used as a dispersion medium to prepare a slurry. , This slurry was applied to both sides of a copper foil having a thickness of 12 μm, the solvent was dried and removed, and then rolled with a roll press to prepare a negative electrode.

<Battery production>
The flat-wound electrode group in which the positive electrode produced above and the negative electrode produced above are wound via a separator (F23DHA, manufactured by Toray Battery Separator Film Co., Ltd.) is housed in a case and has a length of 30 mm and a width of 30 mm. A battery cell having a rectangular parallelepiped shape of 30 mm × thickness 2.0 mm was produced.
Using the battery cell produced above, a laminated battery was produced by the following procedure.
a. 0.6 g of various electrolytic solutions were weighed, injected into the injection port of the battery cell, depressurized, and then the injection port was closed.
b. The sealed battery cell was charged at 12 mA up to 4.4 V while being kept in an atmosphere of 45 ° C., and then discharged at 12 mA up to 3.0 V.
c. A battery was prepared by removing the internal gas of the battery cell discharged to 3.0 V under reduced pressure.

<Battery evaluation>
The charge / discharge characteristics of the battery manufactured above were measured as follows.
a. Capacity retention rate After charging 4.35V at a 1C rate in an atmosphere of 45 ° C., a 3.0V discharge was performed at a 1C rate in the same atmosphere, and the discharge capacity value was used as the initial capacity value. Then, under the same conditions, 300 times were repeated, and the 300th discharge capacity value was used as the post-cycle capacity value. From this initial capacity value and the capacity value after the cycle, the capacity retention rate was calculated using the following formula.
Capacity retention rate (%) = (capacity value after cycle / initial capacity value) x 100

Laminating Comparative Examples 1 and 1-3 using the above battery manufacturing procedure by injecting non-aqueous electrolytes 1-1 to 1-4 into the battery cells prepared using the positive and negative electrodes prepared above. A battery was manufactured.
Next, in an atmosphere of 45 ° C., charging up to 4.35V and discharging up to 3.0V at a 1C rate were repeated 300 times, and the initial capacity value and the discharge capacity value after the cycle after 300 times were measured, and the capacity retention rate was measured. The results are shown in Table 1.

表１に示すように、実施例１〜３の電池は、比較例１に比べて、４．３５Ｖの高電圧化においても良好な寿命特性が得ることができる。

As shown in Table 1, the batteries of Examples 1 to 3 can obtain better life characteristics even at a high voltage of 4.35 V as compared with Comparative Example 1.

<Examples 4 to 6>
<Preparation of positive electrode>
As the positive electrode active material, 90% by mass of the lithium-nickel-manganese-cobalt composite oxide powder having a Ni: Mn: Co ratio of 6: 2: 2, 6% by mass of polyvinylidene fluoride as a binder, and conductivity. N-Methylpyrrolidone is added to a positive electrode mixture made by mixing 4% by mass of acetylene black, which is an agent, to prepare a paste, which is applied to both sides of an aluminum foil current collector having a thickness of 18 μm, and a solvent is applied. After drying and removing, a positive electrode was prepared by rolling with a roll press.

<Manufacturing of negative electrode>
94.8% by mass of artificial graphite-forming carbon powder, 3.0% by mass of styrene-butadiene rubber (SBR) as a binder, and 2.2% by mass of carboxymethyl cellulose aqueous solution were mixed, and water was used as a dispersion medium to prepare a slurry. .. This slurry was applied to both sides of a copper foil having a thickness of 12 μm, the solvent was dried and removed, and then rolled with a roll press to prepare a negative electrode.

<Battery production>
A flat-wound electrode group in which a positive electrode formed by applying a positive electrode mixture to an aluminum current collector and a negative electrode formed by applying a negative electrode mixture to a copper current collector are wound via a separator is housed in a case. Therefore, a battery cell having a shape of width 30 mm × height 30 mm × thickness 2.0 mm was produced.
Using the battery cell produced above, a laminated battery was produced by the following procedure.
a. 0.6 g of various electrolytic solutions were weighed, injected into the injection port of the battery cell, depressurized, and then the injection port was closed.
b. The sealed battery cell was charged at 9 mA up to 4.3 V while being kept in an atmosphere of 45 ° C., and then discharged at 9 mA up to 3.0 V.
c. A battery was prepared by removing the internal gas of the battery cell discharged to 3.0 V under reduced pressure.

<Battery evaluation>
The charge / discharge characteristics of the battery manufactured above were measured as follows.
a. Capacity retention rate After charging 4.2V at a 1C rate in an atmosphere of 45 ° C., a 3.0V discharge was performed at a 1C rate in the same atmosphere, and the discharge capacity value was used as the initial capacity value. Then, under the same conditions, 300 times were repeated, and the 300th discharge capacity value was used as the post-cycle capacity value. From this initial capacity value and the capacity value after the cycle, the capacity retention rate was calculated using the following formula.
Capacity retention rate (%) = (capacity value after cycle / initial capacity value) x 100
b. Volume change rate The initial volume value of the battery in which the battery was submerged in a liquid under an atmosphere of 25 ° C. was measured. Next, the battery was charged to 4.2 V at a 1 C rate in an atmosphere of 45 ° C., and then discharged to 3.0 V at a 1 C rate in the same atmosphere for one cycle. Under the same conditions, it was repeated 300 times. After repeating 300 times, the volume value of the battery was measured after the cycle in the same manner as the initial volume value. From this initial volume value and the volume value after the cycle, the volume change rate was calculated using the following formula.
Volume change rate (%) = (volume value after cycle / initial volume value) x 100

Comparative Examples 2 and 4 were used by injecting the non-aqueous electrolytes 1-1 and 2-1 to 2-3 into the battery cells prepared using the positive electrode and the negative electrode prepared above, and using the above battery manufacturing procedure. A laminated battery of ~ 6 was produced.
Next, charging up to 4.2 V and discharging up to 3.0 V at a 1 C rate in an atmosphere of 45 ° C. were repeated 300 times, and the initial capacitance value and the initial volume value and the post-cycle discharge capacity value and the post-cycle volume after 300 times were repeated. The values were measured to determine the capacity retention rate and volume change rate, and the results are shown in Table 2.

As shown in Table 2, the batteries of Examples 4 to 6 can obtain better life characteristics and can significantly suppress the volume change of the batteries as compared with Comparative Example 2. That is, even if the Ni content in the positive electrode active material is high, good life characteristics can be obtained, and the volume change of the battery can be significantly suppressed.

The non-aqueous electrolyte solution for a power storage device of the present invention is used for a power storage device such as a lithium ion secondary battery, and is used as a power source for various consumer devices such as mobile phones, smartphones, and notebook computers, a power source for industrial devices, a storage battery, and a power source for automobiles. Widely used for such purposes.

Claims (5)

A non-aqueous electrolyte solution for a lithium ion secondary battery in which the positive electrode active material contains a lithium-containing transition metal composite oxide and the negative electrode active material contains a carbon material (excluding silicon and tin).
A boric acid compound obtained by dissolving an electrolyte in a non-aqueous solvent, wherein the electrolyte is a lithium salt dissolved in the non-aqueous solvent, and is composed of tetraboric acid or a salt thereof, or metaboric acid or a salt thereof, and the following. A non-aqueous electrolyte solution for a lithium ion secondary battery, which comprises a sulfonic acid compound composed of a cyclic or chain disulfonate or an ester having two sulfonic acid groups represented by the formula (1). ..
M _1- O- (O =) ₂ SC (R ₁ R ₂ ) -S (= O) _2- O-M ₂ (1)
(In the formula (1), R ₁ and R ₂ have a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 2 to 6 carbon atoms, or an alkenyl group having 1 to 6 carbon atoms. Alkoxy groups having. M ₁ and M ₂ are alkali metals or alkyl groups having 1 to 6 carbon atoms.) The lithium ion secondary battery according to claim 1, which contains 0.01 to 1% by mass of the boric acid compound and 0.01 to 3% by mass of the sulfonic acid compound in the non-aqueous electrolytic solution. Non-aqueous electrolyte. A lithium ion secondary battery comprising the non-aqueous electrolyte solution according to claim 1 or 2. The lithium ion secondary battery according to claim 3 , wherein a layered rock salt structure type lithium-containing transition metal composite compound represented by the following formula (2) is used as a positive electrode active material.
_{Li (Ni x Co y Mn z} ) O 2 (2)
(In the formula, x is 0.2 ≦ x ≦ 0.9, y is 0 ≦ y ≦ 0.5, and z is 0 ≦ z ≦ 0.9.) The lithium ion secondary battery according to claim 4 , wherein in the formula (2), x is larger than 0.5 and y is smaller than 0.3.