JP6081264B2 - Non-aqueous electrolyte additive, non-aqueous electrolyte, and electricity storage device - Google Patents

Description

The present invention relates to an additive for a non-aqueous electrolyte that can form a stable solid electrolyte interface on an electrode surface and improve battery characteristics such as battery life and capacity when used in an electricity storage device. The present invention also relates to a non-aqueous electrolyte using the non-aqueous electrolyte additive and an electricity storage device using the non-aqueous electrolyte.

In recent years, research on non-aqueous electrolyte secondary batteries represented by lithium ion batteries has been extensively conducted as interest in solving environmental problems and realizing a sustainable recycling society has increased. In particular, lithium ion batteries are used as power sources for notebook computers, mobile phones and the like because of their high operating voltage and energy density. These lithium ion batteries are expected to have higher energy density and higher capacity compared to lead batteries and nickel cadmium batteries.

However, the lithium ion battery has a problem that the capacity of the battery decreases with the progress of the charge / discharge cycle. This is due to the fact that the electrolytic solution is decomposed by electrode reaction, the impregnation of the electrolyte into the electrode active material layer is lowered, and the lithium ion intercalation efficiency is lowered with the progress of the long charge / discharge cycle. It is mentioned in.

A method of adding various additives to an electrolytic solution has been studied as a method of suppressing a decrease in battery capacity with the progress of a charge / discharge cycle. The additive is decomposed during the first charge and discharge to form a film called a solid electrolyte interface (SEI) on the electrode surface. Since the SEI is formed in the first cycle of the charge / discharge cycle, electricity is not consumed for the decomposition of the electrolytic solution, and lithium ions can move back and forth through the SEI. That is, the formation of SEI is considered to play a major role in preventing deterioration of the secondary battery when the charge / discharge cycle is repeated and improving battery characteristics, storage characteristics, load characteristics, and the like.

For example, Patent Documents 1 to 3 disclose cyclic monosulfonic acid esters as additives for an electrolytic solution that forms SEI. Patent Document 4 discloses a sulfur-containing aromatic compound, and Patent Document 5 discloses a disulfide compound. Furthermore, Patent Documents 6 to 9 disclose disulfonic acid esters.
Patent Documents 10 to 13 propose an electrolytic solution containing vinylene carbonate or vinyl ethylene carbonate, and Patent Documents 14 and 15 propose an electrolytic solution containing 1,3-propane sultone or butane sultone. Yes.

JP 63-102173 A JP 2000-003724 A JP 11-339850 A JP 05-258753 A JP 2001-052735 A JP 2009-038018 A JP-A-2005-203341 JP 2004-281325 A JP 2005-228631 A Japanese Unexamined Patent Publication No. 04-87156 Japanese Patent Laid-Open No. 05-74486 Japanese Patent Application Laid-Open No. 08-45545 JP 2001-6729 A JP 63-102173 A Japanese Patent Laid-Open No. 10-50342

SEI formed as a film on the electrode surface by the additive used in the electrolytic solution is deeply involved in many battery characteristics such as cycle characteristics, charge / discharge efficiency, and internal resistance.
For example, an electrolytic solution using a vinylene carbonate compound disclosed in Patent Documents 10 to 15 or a sultone compound such as 1,3-propane sultone as an additive is generated by electroreductive decomposition on the negative electrode surface. It is possible to suppress the irreversible capacity drop by the SEI film. For this reason, vinylene carbonate compounds and sultone compounds are frequently used as additives for electrolytic solutions. However, although the SEI film by these compounds functions as an electrode protecting action, since the ionic conductivity of Li ions is low, the performance of reducing the internal resistance was small. In addition, because it does not have enough strength to withstand long-term use, the SEI coating decomposes or cracks during use, exposing the negative electrode surface, causing degradation of the electrolyte solvent and reducing battery characteristics. There was a problem to do. In addition, there is a problem that cracks occur due to the deterioration of SEI under high temperature conditions, and the internal resistance increases with the enlargement of the coating.
As described above, conventional additives for non-aqueous electrolytes have not obtained sufficient performance and have room for improvement. That is, a novel electrolyte additive that improves the battery characteristics of a non-aqueous electrolyte secondary battery by forming SEI on the electrode surface with excellent stability and improving cycle characteristics, charge / discharge efficiency, internal resistance, etc. Development was desired.

The present invention provides an additive for a non-aqueous electrolyte that can form a stable solid electrolyte interface on an electrode surface and improve battery characteristics such as battery life and capacity when used in an electricity storage device. For the purpose. Another object of the present invention is to provide a non-aqueous electrolyte using the additive for non-aqueous electrolyte and an electricity storage device using the non-aqueous electrolyte.

The present invention is an additive for a non-aqueous electrolyte composed of a disulfonic acid succinimide compound represented by the following formula (1) (hereinafter also referred to as “disulfonic acid succinimide compound according to the present invention”).

In formula (1), R ¹ , R ² , R ³ , and R ⁴ are either hydrogen, halogen, an optionally substituted alkyl group having 1 to 6 carbon atoms, or R ¹ and R ² indicating any bets is linked optionally substituted o- phenylene group R ³ and R ^4.
The present invention is described in detail below.

The present inventors have added a disulfonic acid succinimide compound having a specific structure to an electrolytic solution using a non-aqueous solvent as a solvent, thereby providing a stable solid electrolyte interface on the electrode surface when used in an electricity storage device. Has been found to improve battery characteristics such as battery life and capacity, and the present invention has been completed.

In the formula (1), the halogen represented by R ¹ , R ² , R ³ and R ⁴ is preferably fluorine. By being fluorine, the disulfonic acid succinimide compound according to the present invention exhibits low LUMO energy that is susceptible to electrochemical reduction.

In the formula (1), R ^{1, R} 2, ^R 3 ^and, if the number of carbon atoms in the alkyl group represented by R ⁴ is less than 7, the solubility in the nonaqueous solvent may be lowered. ^{R 1, R 2, R 3} , and a preferred upper limit of the carbon number of the alkyl group represented by ^{R 4} is 4.

In the formula (1), the optionally substituted alkyl group represented by R ¹ , R ² , R ³ and R ⁴ is, for example, a methyl group, ethyl Group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group and the like. Of these, a methyl group is preferable.
Further, when the alkyl group represented by R ¹ , R ² , R ³ , and R ⁴ is substituted, the number of substitutions is n to (2n + 1) arbitrary substituents with respect to n carbon atoms. Is the number of replacements.

When the alkyl group represented by R ¹ , R ² , R ³ , and R ⁴ is substituted, it is preferably substituted with halogen, and more preferably substituted with fluorine. By being substituted with fluorine, the disulfonic acid succinimide compound according to the present invention exhibits low LUMO energy that is susceptible to electrochemical reduction.

In the formula (1), when any of R ¹ and R ² and any of R ³ and R ⁴ are connected to form an o-phenylene group which may be substituted, a benzene ring is contained, The disulfonic acid succinimide compound according to the invention exhibits a low LUMO energy that is susceptible to electrochemical reduction.

In the formula (1), when an o-phenylene group formed by linking any of R ¹ and R ² and any of R ³ and R ⁴ is substituted, an alkyl group having 1 to 4 carbon atoms or a halogen is used. It is preferably substituted.
When the o-phenylene group is substituted with an alkyl group, if the alkyl group on the o-phenylene group has 5 or more carbon atoms, the solubility in a non-aqueous solvent may be reduced. The preferable upper limit of the carbon number of the alkyl group on the o-phenylene group is 2.
When the o-phenylene group is substituted with halogen, it is preferably substituted with fluorine.

Specific examples of the disulfonic acid succinimide compound represented by the formula (1) include methanedisulfonic acid bis (phenylamide), methanedisulfonic acid bis (methylphenylamide), and methanedisulfonic acid bis (ethylphenylamide). , Methanedisulfonic acid bis (propylphenylamide), methanedisulfonic acid bis (butylphenylamide), methanedisulfonic acid bis (pentylphenylamide), methanedisulfonic acid bis (hexylphenylamide), methanedisulfonic acid bis (dibenzylamide) , Methanedisulfonic acid bis (benzylmethylamide), methanedisulfonic acid bis (benzylethylamide), methanedisulfonic acid bis (benzylpropylamide), methanedisulfonic acid bis (benzyl-n-butylamide), meta Disulfonic acid bis (benzylpentylamide), methanedisulfonic acid bis (benzylhexylamide), methanedisulfonic acid bisdiphenylamide, methanedisulfonic acid bis (benzylphenylamide), methanedisulfonic acid bis (phenethylphenylamide), methanedisulfonic acid bis (Phenyl (3-phenylpropyl) amide), methanedisulfonic acid bis (phenyl (4-phenylbutyl) amide), methanedisulfonic acid bis (phenyl (5-phenylpentyl) amide), methanedisulfonic acid bis (phenyl (6- Phenylhexyl) amide), methanedisulfonic acid bis (phenyl (3-phenylpropyl) amide), methanedisulfonic acid bis (4-fluorophenylamide), methanedisulfonic acid bis [(4-fluorophenyl Methylamide], methanedisulfonic acid bis [(4-fluorophenyl) ethylamide], methanedisulfonic acid bis [(4-fluorophenyl) propylamide], methanedisulfonic acid bis [(4-fluorophenyl) n-butylamide], methanedisulfone Acid bis [(4-fluorophenyl) pentylamide], methanedisulfonic acid bis [(4-fluorophenyl) hexylamide], methanedisulfonic acid bis [(4-fluorobenzyl) methylamide], methanedisulfonic acid bis [(4- Fluorobenzyl) ethylamide], methanedisulfonic acid bis [(4-fluorobenzyl) propylamide], methanedisulfonic acid bis [(4-fluorobenzyl) n-butyramide], methanedisulfonic acid bis [(4-fluorobenzyl) pentyla Amide], methanedisulfonic acid bis [(4-fluorobenzyl) hexylamide], methanedisulfonic acid bis [(4-fluorophenyl) phenylamide], methanedisulfonic acid bis [(4-fluorobenzyl) phenylamide], methanedisulfone Acid bis [(4-fluorophenethyl) phenylamide], methanedisulfonic acid bis [phenyl (3- (4-fluorophenyl) propylamide], methanedisulfonic acid bis [phenyl (4- (4-fluorophenyl) butyramide], And bis [phenyl (5- (4-fluorophenyl) pentylamide] methanedisulfonate.

The additive for a non-aqueous electrolyte of the present invention is a disulfonic acid succinimide compound according to the present invention, since the resulting non-aqueous electrolyte exhibits a high discharge capacity retention ratio and a low internal resistance ratio. A compound represented by (2-1), a compound represented by the following formula (2-2), a compound represented by the following formula (2-3), a compound represented by the following formula (2-4), The compound represented by the following formula (2-5), the compound represented by the following formula (2-6), the compound represented by the following formula (2-7), and the following formula (2-8) It is preferably composed of at least one disulfonic acid succinimide compound selected from the group consisting of a compound, a compound represented by the following formula (2-9), and a compound represented by the following formula (2-10).
In formulas (2-2), (2-4), and (2-9), “Me” is a methyl group, “Hex” in formula (2-3) is a hexyl group, and formula (2- “Et” in 4) represents an ethyl group.

As a method for producing the disulfonic acid succinimide compound according to the present invention, for example, succinimide type secondary amine or phthalimide type secondary amine (R ¹ , R ⁴⁾ having R ¹ , R ² , R ³ , and R ⁴ as substituents. R ² , R ³ , and R ⁴ are the same as those in formula (1)) and a method of reacting methanedisulfonyl chloride.
Specifically, for example, when producing the disulfonic acid succinimide compound represented by the above formula (2-1), first, methanedisulfonyl chloride is dropped into succinimide, and then triethylamine is dropped and stirred. After completion of the reaction, a method of extracting the organic layer and filtering the crystals precipitated by the crystallization operation can be used. In addition, when manufacturing this compound, reaction solvents, such as 1, 2- dimethoxyethane, can also be used as needed.
Moreover, said Formula (2-2), (2-3), (2-4), (2-5), (2-6), (2-7), (2-8), (2-9) ) And pyrrolidine-2,5-dione in the method for producing the disulfonic acid amide compound represented by the formula (2-1) when producing the disulfonic acid succinimide compound represented by (2-10) Instead of 3-methylsuccinimide, 3-hexylsuccinimide, 3-ethyl-4-methylsuccinimide, 3,4-di (2,2,2-trifluoroethyl) succinimide, and 3,3-ditrifluoromethylsuccinimide, respectively. A method of reacting 3-fluorosuccinimide, phthalimide, 5-methylphthalimide, 4-fluorophthalimide with methanedisulfonyl chloride can be used.

In the disulfonic acid succinimide compound according to the present invention, the preferred lower limit of the lowest unoccupied molecular orbital (LUMO) energy is -2.8 eV, and the preferred upper limit is 0.0 eV. When the LUMO energy is less than −2.8 eV, excessive decomposition may occur, and a film showing high resistance may be formed on the electrode. When the LUMO energy exceeds 0.0 eV, stable SEI may not be formed on the electrode surface of a nonaqueous electrolyte secondary battery or the like. A more preferable lower limit of the LUMO energy is −1.5 eV, and a more preferable upper limit is −0.15 eV.
The “lowest unoccupied molecular orbital (LUMO) energy” is calculated by combining a semi-empirical molecular orbital calculation method: PM3 and a density functional method: B3LYP method. Specifically, in the present invention, a value calculated using Gaussian 03 (Revision B.03, software manufactured by Gaussian, USA) is used.

Since the disulfonic acid succinimide compound according to the present invention exhibits low LUMO energy that is susceptible to electrochemical reduction, the non-aqueous electrolyte additive of the present invention comprising the compound is a power storage device such as a non-aqueous electrolyte secondary battery. When added to a non-aqueous electrolyte used in a device, stable SEI can be formed on the electrode surface to improve battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance. In addition, since the disulfonic acid succinimide compound according to the present invention is stable against moisture and temperature changes, the non-aqueous electrolyte additive of the present invention comprising the compound can be stored at room temperature for a long period of time. It is. Therefore, the non-aqueous electrolyte containing the non-aqueous electrolyte additive can withstand long-term storage and use.
The non-aqueous electrolyte containing the additive for non-aqueous electrolyte, the non-aqueous solvent, and the electrolyte of the present invention is also one aspect of the present invention.

The content of the additive for non-aqueous electrolyte of the present invention in the non-aqueous electrolyte of the present invention (that is, the content of the disulfonic acid succinimide compound represented by the formula (1)) is not particularly limited, but the preferred lower limit is 0.005 mass% and a preferable upper limit is 10 mass%. When the content of the additive for non-aqueous electrolyte of the present invention is less than 0.005% by mass, there is a possibility that stable SEI cannot be sufficiently formed due to an electrochemical reaction on the electrode surface when used in an electricity storage device. . When the content of the additive for non-aqueous electrolyte of the present invention exceeds 10% by mass, not only is it difficult to dissolve, but also the viscosity of the non-aqueous electrolyte increases, and it becomes impossible to ensure sufficient ion mobility. The electroconductivity of the electrolytic solution cannot be sufficiently ensured, and there is a possibility that the discharge characteristics, the charge characteristics, etc. may be hindered when used in an electricity storage device. The more preferable lower limit of the content of the additive for non-aqueous electrolyte of the present invention is 0.01% by mass.

As the non-aqueous solvent, an aprotic solvent is preferable from the viewpoint of keeping the viscosity of the obtained non-aqueous electrolyte low. Among these, it is preferable to contain at least one selected from the group consisting of cyclic carbonates, chain carbonates, aliphatic carboxylic acid esters, lactones, lactams, cyclic ethers, chain ethers, and halogen derivatives thereof.

Specific examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate, chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, methyl acetate, ethyl acetate, and propionic acid. Aliphatic carboxylic acid esters such as methyl, ethyl propionate, methyl butyrate, methyl isobutyrate and methyl trimethylacetate, lactones such as γ-butyrolactone, lactams such as ε-caprolactam and N-methylpyrrolidone, tetrahydrofuran, 2- Cyclic ethers such as methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, chain ethers such as 1,2-ethoxyethane, ethoxymethoxyethane, 4-fluoro-1,3-dioxolan-2-one, 4- Chloro-1,3-dioxolan-2-o And halogen derivatives such as 4,5-difluoro-1,3-dioxolan-2-one. These non-aqueous solvents may be used alone or in combination of two or more.

The electrolyte is preferably a lithium salt that serves as a source of lithium ions. Among these, at least one selected from the group consisting of LiAlCl ₄ , LiBF ₄ , LiPF ₆ , LiClO ₄ , LiAsF ₆ , and LiSbF ₆ is preferable, and LiBF ₄ and LiPF ₆ are more preferable. These electrolytes may be used alone or in combination of two or more.

The concentration of the electrolyte in the nonaqueous electrolytic solution of the present invention is not particularly limited, but a preferred lower limit is 0.1 mol / L and a preferred upper limit is 2.0 mol / L. When the concentration of the electrolyte is less than 0.1 mol / L, the conductivity of the non-aqueous electrolyte cannot be sufficiently ensured, and the discharge characteristics and the charge characteristics are hindered when used in an electricity storage device. There is a fear. When the concentration of the electrolyte exceeds 2.0 mol / L, the viscosity increases and the mobility of ions cannot be sufficiently ensured, so that the conductivity of the non-aqueous electrolyte cannot be sufficiently secured and When used in a device, there is a risk of disturbing discharge characteristics and charge characteristics. A more preferred lower limit of the electrolyte concentration is 0.5 mol / L, and a more preferred upper limit is 1.5 mol / L.

An electricity storage device including the non-aqueous electrolyte, positive electrode, and negative electrode of the present invention is also one aspect of the present invention. Examples of the electricity storage device include non-aqueous electrolyte secondary batteries and electric double layer capacitors. Of these, lithium ion batteries and lithium ion capacitors are preferred.

FIG. 1 is a cross-sectional view schematically showing an example of the electricity storage device of the present invention.
In FIG. 1, an electricity storage device 1 includes a positive electrode plate 4 in which a positive electrode active material layer 3 is provided on one surface side of a positive electrode current collector 2, and a negative electrode active material layer 6 on one surface side of a negative electrode current collector 5. Has a negative electrode plate 7. The positive electrode plate 4 and the negative electrode plate 7 are disposed to face each other with a separator 9 provided in the non-aqueous electrolyte 8 and the non-aqueous electrolyte 8 of the present invention.

In the electricity storage device of the present invention, as the positive electrode current collector 2 and the negative electrode current collector 5, for example, a metal foil made of a metal such as aluminum, copper, nickel, stainless steel, or the like can be used.

In the electricity storage device of the present invention, as the positive electrode active material used for the positive electrode active material layer 3, lithium-containing composite oxides are preferably used. Specifically, for example, LiMnO ₂ , LiFeO ₂ , LiCoO ₂ , LiMn ₂ O ₄ , Examples include lithium-containing composite oxides such as Li ₂ FeSiO ₄ .

In the electricity storage device of the present invention, examples of the negative electrode active material used for the negative electrode active material layer 6 include a material capable of inserting and extracting lithium. Examples of such materials include carbon materials such as graphite and amorphous carbon, and oxide materials such as indium oxide, silicon oxide, tin oxide, zinc oxide, and lithium oxide.
In addition, as the negative electrode active material, lithium metal and a metal material capable of forming an alloy with lithium can be used. Examples of the metal capable of forming an alloy with lithium include Cu, Sn, Si, Co, Mn, Fe, Sb, Ag, and the like, and are composed of binary or ternary containing these metals and lithium. An alloy can also be used.
These negative electrode active materials may be used alone or in combination of two or more.
In the electricity storage device of the present invention, as the separator 9, for example, a porous film made of polyethylene, polypropylene, fluororesin, or the like can be used.

According to the present invention, when used in an electricity storage device, a non-aqueous electrolyte additive that can form a stable solid electrolyte interface on the electrode surface to improve battery characteristics such as battery life and capacity. Can be provided. Moreover, according to this invention, the nonaqueous electrolyte using this additive for nonaqueous electrolytes, and the electrical storage device using this nonaqueous electrolyte can be provided.

It is sectional drawing which showed typically an example of the electrical storage device of this invention.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
(Preparation of methanedisulfonic acid bis (succinimide) (compound 1))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 10.9 g (0.11 mol) of succinimide and 70.0 g of 1,2-dimethoxyethane, 10.7 g (0.05 mol) of methanedisulfonyl chloride dissolved in 20.0 g of 2-dimethoxyethane was added dropwise over 20 minutes while maintaining at 0 ° C. While maintaining the same temperature, 10.6 g (0.10 mol) of triethylamine mixed with 20.0 g of 1,2-dimethoxyethane was added dropwise over 1 hour and stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. A portion of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried, whereby methanedisulfonic acid represented by the above formula (2-1). 5.1 g (0.015 mol) of bis (succinimide) was obtained. The yield of bis (succinimide) methanedisulfonate was 30.4% based on methanedisulfonyl chloride.
In addition, the obtained methane disulfonic acid bis (succinimide) was able to be identified from having the following physical property.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 5.53 (s, 2H), 7.23 (dd, 8H)

(Example 2)
(Preparation of methanedisulfonic acid bis (3-methylsuccinimide) (compound 2))
A 200 mL four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel was charged with 12.4 g (0.11 mol) of 3-methylsuccinimide and 70.0 g of 1,2-dimethoxyethane. 10.7 g (0.05 mol) of methanedisulfonyl chloride dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 20 minutes while maintaining the temperature at 0 ° C. Subsequently, 10.6 g (0.10 mol) of triethylamine dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 1 hour while maintaining the same temperature, and the mixture was stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. A part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried, whereby methanedisulfonic acid represented by the above formula (2-2). 11.4 g (0.031 mol) of bis (3-methylsuccinimide) was obtained. The yield of bis (3-methylsuccinimide) methanedisulfonate was 62.5% based on methanedisulfonyl chloride.
The obtained methanedisulfonic acid bis (3-methylsuccinimide) could be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 5.53 (s, 2H), 2.90 (m, 2H), 2.69 (d, 4H), 1.24 (d , 6H)

(Example 3)
(Production of methanedisulfonic acid bis (3-hexylsuccinimide) (compound 3))
A 200 mL four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel was charged with 20.1 g (0.11 mol) of 3-hexylsuccinimide and 70.0 g of 1,2-dimethoxyethane. 10.7 g (0.05 mol) of methanedisulfonyl chloride dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 20 minutes while maintaining the temperature at 0 ° C. Subsequently, 10.6 g (0.10 mol) of triethylamine dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 1 hour while maintaining the same temperature, and the mixture was stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation, and the solvent was distilled off under reduced pressure at 25 ° C. from the obtained organic layer. Subsequently, 40.0 g of toluene was added, and 10.0 g of methanol was added dropwise to precipitate crystals. The precipitated crystals were filtered and the obtained crystals were dried to obtain 3.5 g (0.007 mol) of methanedisulfonic acid bis (3-hexylsuccinimide) represented by the formula (2-3). . The yield of bis (3-hexylsuccinimide) methanedisulfonate was 13.1% based on methanedisulfonyl chloride.
The obtained methanedisulfonic acid bis (3-hexylsuccinimide) could be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 5.53 (s, 2H), 2.72 (m, 2H), 2.69 (dd, 4H), 1.53 (m 4H), 1.29 (m, 12H), 1.33 (m, 4H), 0.96 (t, 6H)

Example 4
(Production of methanedisulfonic acid bis (3-ethyl-4-methylsuccinimide) (compound 4))
In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 15.5 g (0.11 mol) of 3-ethyl-4-methylsuccinimide and 1,2-dimethoxyethane 70 were added. 0.07 g and 10.7 g (0.05 mol) of methanedisulfonyl chloride dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 50 minutes while maintaining the temperature at 0 ° C. While maintaining the same temperature, 10.6 g (0.10 mol) of triethylamine dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 50 minutes and stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation, and the solvent was distilled off under reduced pressure at 25 ° C. from the obtained organic layer. Subsequently, 35.0 g of methanol was added to precipitate crystals. The precipitated crystals were filtered and the obtained crystals were dried, whereby 2.7 g (0.019 mol) of bis (3-ethyl-4-methylsuccinimide) methanedisulfonate represented by the above formula (2-4). ). The yield of bis (3-ethyl-4-methylsuccinimide) methanedisulfonate was 38.2% based on methanedisulfonyl chloride.
The obtained methanedisulfonic acid bis (3-ethyl-4-methylsuccinimide) could be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 5.53 (s, 2H), 2.89 (m, 2H), 2.71 (m, 2H), 1.57 (m 4H), 1.24 (d, 6H), 1.96 (t, 6H)

(Example 5)
(Preparation of methanedisulfonic acid bis (3,4-bis (2,2,2-trifluoroethyl) succinimide) (compound 5))
In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 28.9 g (0.11 mol) of 3,4-di (2,2,2-trifluoroethyl) succinimide, 10.7 g (0.05 mol) of methanedisulfonyl chloride charged with 70.0 g of 1,2-dimethoxyethane and dissolved in 20.0 g of 1,2-dimethoxyethane was maintained for 20 minutes while maintaining at 0 ° C. It was dripped over. While maintaining the same temperature, 10.6 g (0.10 mol) of triethylamine dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 11 hours, and the mixture was stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. Part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried, whereby methanedisulfonic acid represented by the above formula (2-5). 18.0 g (0.027 mol) of bis (3,4-di (2,2,2-trifluoroethyl) succinimide) was obtained. The yield of methanedisulfonic acid bis (3,4-di (2,2,2-trifluoroethyl) succinimide) was 53.0% based on methanedisulfonyl chloride.
The resulting methanedisulfonic acid bis (3,4-di (2,2,2-trifluoroethyl) succinimide) could be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 5.53 (s, 2H), 2.71 (m, 4H) 2.05 (m, 8H)

(Example 6)
(Production of bis (3,3-ditrifluoromethylsuccinimide) methanedisulfonate (compound 6))
In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 25.9 g (0.11 mol) of 3,3-ditrifluoromethylsuccinimide and 1,2-dimethoxyethane 70 were added. 0.07 g and 10.7 g (0.05 mol) of methanedisulfonyl chloride dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 20 minutes while maintaining the temperature at 0 ° C. Subsequently, while maintaining the same temperature, 10.6 g (0.10 mol) of triethylamine dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 1 hour and stirred overnight while maintaining the same temperature. .
After completion of the reaction, the reaction solution was filtered, and 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. Part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried, whereby methanedisulfonic acid represented by the above formula (2-6) 7.9 g (0.013 mol) of bis (3,3-ditrifluoromethylsuccinimide) was obtained. The yield of bis (3,3-ditrifluoromethylsuccinimide) methanedisulfonate was 25.4% based on methanedisulfonyl chloride.
In addition, the obtained methane disulfonic acid bis (3, 3- ditrifluoromethyl succinimide) was able to be identified from having the following physical property.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 5.53 (s, 2H), 2.65 (d, 4H)

(Example 7)
(Production of methanedisulfonic acid bis (3-fluorosuccinimide) (compound 7))
In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 12.9 g (0.11 mol) of N- (3-fluorosuccinimide) and 1,2-dimethoxyethane 70 0.07 g and 10.7 g (0.05 mol) of methanedisulfonyl chloride dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 20 minutes while maintaining the temperature at 0 ° C. Subsequently, 10.6 g (0.10 mol) of triethylamine dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 1 hour while maintaining the same temperature, and the mixture was stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and 150.0 g of toluene, 80.0 g of water, and 70.0 g of 1,2-dimethoxyethane were added to the filtrate for liquid separation. Part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried, whereby methanedisulfonic acid represented by the above formula (2-7). 5.2 g (0.014 mol) of bis (3-fluorosuccinimide) was obtained. The yield of methanedisulfonic acid bis (3-fluorosuccinimide) was 28.7% based on methanedisulfonyl chloride.
The obtained methanedisulfonic acid bis (3-fluorosuccinimide) could be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 5.53 (s, 2H), 4.56 (m, 2H), 2.89 (d, 4H)

(Example 8)
(Production of methanedisulfonic acid bis (phthalimide) (compound 8))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 16.2 g (0.11 mol) of phthalimide and 70.0 g of 1,2-dimethoxyethane, 10.7 g (0.05 mol) of methanedisulfonyl chloride dissolved in 20.0 g of 2-dimethoxyethane was added dropwise over 20 minutes while maintaining at 0 ° C. Subsequently, 10.6 g (0.10 mol) of triethylamine dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 1 hour while maintaining the same temperature, and the mixture was stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and 150.0 g of toluene, 80.0 g of water, and 70.0 g of 1,2-dimethoxyethane were added to the filtrate for liquid separation. Part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried, whereby methanedisulfonic acid represented by the above formula (2-8). 6.1 g (0.014 mol) of bis (phthalimide) was obtained. The yield of methanedisulfonic acid bis (phthalimide) was 28.7% based on methanedisulfonyl chloride.
The obtained methanedisulfonic acid bis (phthalimide) could be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 8.20-8.11 (m, 4H), 7.71-7.66 (m, 4H), 5.53 (s, 2H)

Example 9
(Production of methanedisulfonic acid bis (5-methylphthalimide) (compound 9))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 17.7 g (0.11 mol) of 5-methylphthalimide and 70.0 g of 1,2-dimethoxyethane. 10.7 g (0.05 mol) of methanedisulfonyl chloride dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 20 minutes while maintaining the temperature at 0 ° C. While maintaining the same temperature, 10.6 g (0.10 mol) of triethylamine dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 11 hours, and the mixture was stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. Part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried, whereby methanedisulfonic acid represented by the above formula (2-9). 12.5 g (0.027 mol) of bis (5-methylphthalimide) was obtained. The yield of methanedisulfonic acid bis (5-methylphthalimide) was 53.0% based on methanedisulfonyl chloride.
The obtained methanedisulfonic acid bis (5-methylphthalimide) could be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 8.04-8.01 (m, 2H), 7.9-7.91 (m, 2H) 7.51-7.48 (M, 2H), 5.53 (s, 2H), 2.35 (s, 6H)

(Example 10)
(Production of methanedisulfonic acid bis (4-fluorophthalimide) (compound 10))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 18.2 g (0.11 mol) of 4-fluorophthalimide and 70.0 g of 1,2-dimethoxyethane. 10.7 g (0.05 mol) of methanedisulfonyl chloride dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 20 minutes while maintaining the temperature at 0 ° C. While maintaining the same temperature, 10.6 g (0.10 mol) of triethylamine dissolved in 20.0 g of 1,2-dimethoxyethane was added dropwise over 11 hours, and the mixture was stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and then 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. A portion of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried, whereby methanedisulfonic acid represented by the above formula (2-10). 12.7 g (0.027 mol) of bis (4-fluorophthalimide) was obtained. The yield of bis (4-fluorophthalimide) methanedisulfonate was 53.0% based on methanedisulfonyl chloride.
The obtained methanedisulfonic acid bis (5-methylphthalimide) could be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 7.99-7.92 (m, 2H), 7.70-7.62 (m, 2H) 7.42-7.38 (M, 2H), 5.53 (s, 2H), 2.35 (s, 6H)

(Comparative Example 1)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that Compound 1 was not used.

(Comparative Example 2)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 2 except that 1,3-propane sultone was added in such a manner that the content ratio was 1.0% by mass instead of Compound 1.

(Comparative Example 3)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 2 except that vinylene carbonate (VC) was added so that the content ratio was 1.0% by mass instead of Compound 1.

(Comparative Example 4)
A nonaqueous electrolytic solution was prepared in the same manner as in Comparative Example 3 except that the content of vinylene carbonate (VC) was 2.0% by mass.

(Comparative Example 5)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 2 except that fluoroethylene carbonate (FEC) was added so that the content ratio was 1.0% by mass instead of Compound 1.

(Comparative Example 6)
A nonaqueous electrolytic solution was prepared in the same manner as in Comparative Example 5 except that the content ratio of fluoroethylene carbonate (FEC) was 2.0% by mass.

<Evaluation>
(Measurement of LUMO energy)
For compounds 1-10 obtained in the examples, semi-empirical molecular orbital calculations were performed with Gaussian 03 software to measure LUMO (lowest unoccupied molecular orbital) energy. Table 1 shows LUMO energies of Compounds 1 to 10 obtained by orbit calculation.

From Table 1, the LUMO energy of the disulfonic acid succinimide compounds (compounds 1 to 10) according to the present invention is about −0.32 eV to about −0.62 eV showing a negative value, and these disulfonic acid amide compounds are low. It can be seen that it has LUMO energy. Therefore, when compounds 1 to 10 are used as non-aqueous electrolyte additives in non-aqueous electrolyte secondary batteries, the solvent of the non-aqueous electrolyte (for example, cyclic carbonate or chain carbonate: LUMO energy of about 1.2 eV) Since the electrochemical reduction of the compounds 1 to 10 occurs earlier and SEI is formed on the electrode, decomposition of solvent molecules in the electrolytic solution can be suppressed. As a result, it is difficult to form a decomposition film of a solvent exhibiting high resistance on the electrode, and an improvement in battery characteristics is expected.
As described above, the disulfonic acid succinimide compound according to the present invention has a sufficiently low LUMO energy, and a novel nonaqueous electrolysis that forms stable SEI on the electrode of a nonaqueous electrolyte secondary battery such as a lithium ion battery. It shows that it is effective as a liquid additive.

(Production of battery)
Disperse uniformly in N-methyl-2-pyrrolidone (NMP) in which LiMn ₂ O ₄ as a positive electrode active material and carbon black as a conductivity imparting agent are dry mixed and polyvinylidene fluoride (PVDF) is dissolved as a binder To prepare a slurry. The obtained slurry was applied on an aluminum metal foil (square shape, thickness 20 μm) serving as a positive electrode current collector, and then NMP was evaporated to prepare a positive electrode sheet. The solid content ratio in the obtained positive electrode sheet was a mass ratio of positive electrode active material: conductivity imparting agent: PVDF = 80: 10: 10.
On the other hand, as the negative electrode sheet, a commercially available graphite coated electrode sheet (manufactured by Hosen Co., Ltd.) was used.
In the nonaqueous electrolytic solution obtained in the same manner as in the above “LSV measurement”, the negative electrode sheet and the positive electrode sheet were laminated via a separator made of polyethylene to produce a cylindrical secondary battery.

(Measurement of discharge capacity maintenance ratio and internal resistance ratio)
Each cylindrical secondary battery obtained was charged at 25 ° C. with a charge rate of 0.3 C, a discharge rate of 0.3 C, a charge end voltage of 4.2 V, and a discharge end voltage of 2.5 V. A discharge cycle test was conducted. Table 2 shows the discharge capacity retention rate (%) and the internal resistance ratio after 200 cycles. The “discharge capacity retention rate (%)” after 200 cycles is obtained by multiplying the value obtained by dividing the discharge capacity (mAh) after the 200 cycle test by the discharge capacity (mAh) after the 10 cycle test by 100. It is. The “internal resistance ratio” after 200 cycles represents the resistance after the 200 cycle test as a relative value when the resistance before the cycle test is 1.

From Table 2, the cylindrical secondary battery using the non-aqueous electrolyte containing the disulfonic acid succinimide compound of the example is on the electrode surface as compared with the cylindrical secondary battery using the non-aqueous electrolyte of the comparative example. It can be seen that SEI that is stable with respect to the charge / discharge cycle is formed. In addition, the non-aqueous electrolyte using the disulfonic acid succinimide compound of the example maintains a lower internal resistance ratio than the non-aqueous electrolyte of the comparative example, and suppresses an increase in internal resistance during the cycle. I understand that I can do it.

According to the present invention, when used in an electricity storage device, a non-aqueous electrolyte additive that can form a stable solid electrolyte interface on the electrode surface to improve battery characteristics such as battery life and capacity. Can be provided. Moreover, according to this invention, the nonaqueous electrolyte using this additive for nonaqueous electrolytes, and the electrical storage device using this nonaqueous electrolyte can be provided.

DESCRIPTION OF SYMBOLS 1 Power storage device 2 Positive electrode current collector 3 Positive electrode active material layer 4 Positive electrode plate 5 Negative electrode current collector 6 Negative electrode active material layer 7 Negative electrode plate 8 Nonaqueous electrolyte 9 Separator

Claims (11)

The additive for non-aqueous electrolytes which consists of a disulfonic-acid succinimide compound represented by following formula (1).

In formula (1), R ¹ , R ² , R ³ , and R ⁴ are either hydrogen, halogen, an optionally substituted alkyl group having 1 to 6 carbon atoms, or R ¹ and R ² indicating any bets is linked optionally substituted o- phenylene group R ³ and R ^4. The compound represented by the following formula (2-1), the compound represented by the following formula (2-2), the compound represented by the following formula (2-3), and the following formula (2-4) Compound, compound represented by the following formula (2-5), compound represented by the following formula (2-6), compound represented by the following formula (2-7), represented by the following formula (2-8) And at least one disulfonic acid succinimide compound selected from the group consisting of a compound represented by the following formula (2-9) and a compound represented by the following formula (2-10). The additive for non-aqueous electrolyte according to claim 1.

The additive for non-aqueous electrolyte according to claim 1 or 2, wherein the disulfonic acid succinimide compound has a minimum unoccupied molecular orbital energy of -2.8 to 0.0 eV. A non-aqueous electrolyte comprising the additive for a non-aqueous electrolyte according to claim 1, 2, or 3, a non-aqueous solvent, and an electrolyte. The nonaqueous electrolytic solution according to claim 4, wherein the nonaqueous solvent is an aprotic solvent. The aprotic solvent is at least one selected from the group consisting of cyclic carbonates, chain carbonates, aliphatic carboxylic acid esters, lactones, lactams, cyclic ethers, chain ethers, and halogen derivatives thereof. The non-aqueous electrolyte according to claim 5, wherein The non-aqueous electrolyte according to claim 4, 5 or 6, wherein the electrolyte contains a lithium salt. Lithium _{salt, LiAlCl 4, LiBF 4, LiPF} 6, LiClO 4, LiAsF 6, and the nonaqueous electrolytic solution according to claim 7, wherein the at least one selected from the group consisting of LiSbF _6. An electricity storage device comprising the nonaqueous electrolytic solution according to claim 4, 5, 6, 7 or 8, a positive electrode, and a negative electrode. The power storage device according to claim 9, wherein the power storage device is a lithium ion battery. The power storage device according to claim 9, wherein the power storage device is a lithium ion capacitor.

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