JP2014194871A - Additive agent for nonaqueous electrolytic solution, nonaqueous electrolytic solution, and electric power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive agent for nonaqueous electrolytic solution and an electric power storage device which enable the improvement of battery life, capacity and the like.SOLUTION: An additive agent for nonaqueous electrolytic solution comprises an imide sulfonate amide compound expressed by the following formula (1). In the formula (1), Rand Rindependently represent a phenyl group which may be substituted; Rand Rindependently represent a hydrogen atom, an alkyl group having 1-6 carbon atoms which may be substituted, or -RX (Rrepresents an alkylene group having 1-6 carbon atoms which may be substituted, and X represents a phenyl group or phenoxy group which may be substituted); Rand Rindependently represent an alkylene group having 0-6 carbon atoms which may be substituted; and M represents a hydrogen atom, a lithium atom, or an alkyl group having 1-6 carbon atoms.

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 an imide sulfonic acid amide compound represented by the following formula (1) (hereinafter also referred to as “an imide sulfonic acid amide compound according to the present invention”). Since the imide sulfonic acid amide compound according to the present invention having the structure represented by the formula (1) easily forms a network polymer by electrical redox decomposition, the SEI formed on the electrode surface is electrically decomposed or physically It is considered that it has high resistance to chemical decomposition and contributes to a high capacity retention rate in the charge / discharge cycle.

In formula (1), R ¹ and R ² each independently represent an optionally substituted phenyl group. R ³ and R ⁴ are each independently hydrogen, an optionally substituted alkyl group having 1 to 6 carbon atoms, or —R ⁷ X (R ⁷ is an optionally substituted carbon atom having 1 to 6 carbon atoms). And X represents an optionally substituted phenyl group or phenoxy group). R ⁵ and R ⁶ are each independently an optionally substituted alkylene group having 0 to 6 carbon atoms. M represents hydrogen, lithium, or an alkyl group having 1 to 6 carbon atoms.
The present invention is described in detail below.

The present inventors have added a imide sulfonic acid amide compound having a specific structure to an electrolyte solution using a non-aqueous solvent as a solvent, thereby providing a stable solid electrolyte on the electrode surface when used in an electricity storage device. It has been found that battery characteristics such as battery life and capacity can be improved by forming an interface, and the present invention has been completed.

In the formula (1), examples of the optionally substituted phenyl group represented by R ¹ and R ² include a phenyl group, a 2-fluorophenyl group, a 3-fluorophenyl group, a 4-fluorophenyl group, 2 -Chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2-bromophenyl group, 3-bromophenyl group, 4-bromophenyl group, 2-iodophenyl group, 3-iodophenyl group, 4-iodophenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2-ethylphenyl group, 3-ethylphenyl group, 4-ethylphenyl group, 2-methoxyphenyl group, 3-methoxyphenyl group, 4- Methoxyphenyl group, 2-ethoxyphenyl group, 3-ethoxyphenyl group, 4-ethoxyphenyl group, 2- (dimethylamino Phenyl group, 3- (dimethylamino) phenyl group, 4- (dimethylamino) phenyl group, phenoxy group, 2-methylphenoxy group, 3-methylphenoxy group, 4-methylphenoxy group, 2-ethylphenoxy group, 3- Ethylphenoxy group, 4-ethylphenoxy group, 2-methoxyphenoxy group, 3-methoxyphenoxy group, 4-methoxyphenoxy group, 2-ethoxyphenoxy group, 3-ethoxyphenoxy group, 4-ethoxyphenoxy group, 2- (dimethyl) Amino) phenoxy group, 3- (dimethylamino) phenoxy group, 4- (dimethylamino) phenoxy group and the like. Of these, a phenyl group is preferable.
Moreover, when the phenyl group shown by R < ¹ > and R < ² > is substituted, it is preferable that a part or all of hydrogen of a phenyl group is substituted by the halogen, and it is more preferable that it is substituted by the fluorine.

In the formula (1), examples of the optionally substituted alkyl group represented by R ³ and R ⁴ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n- Examples thereof include a butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, and an n-hexyl group. Of these, a methyl group is preferable.
In addition, when the alkyl group represented by R ³ and R ⁴ is substituted, it is preferable that part or all of the alkyl group is substituted with halogen, and more preferably substituted with fluorine.

In the formula (1), in the case ^{where R 3} and / or ^{R 4} represents a -R ⁷ X, as the optionally substituted alkylene group having 1 to 6 carbon atoms represented by ^{R 7} is, for example, a methylene group Methylmethylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, 1-methylethylene group, 1-ethylethylene group, n-pentylene group, n-hexalene group and the like. Of these, a methylene group and an ethylene group are preferable.
When the alkylene group represented by R ⁷ is substituted, it is substituted with a halogen, an alkoxy group having 1 to 6 carbon atoms, an optionally substituted phenyl group, or an optionally substituted phenoxy group. It is preferable that it is substituted with halogen, and it is more preferable that it is substituted with halogen.

In the formula (1), when R ³ and / or R ⁴ represents —R ⁷ X, examples of the optionally substituted phenyl group represented by X include a phenyl group and 2-fluorophenyl. Group, 3-fluorophenyl group, 4-fluorophenyl group, 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2-bromophenyl group, 3-bromophenyl group, 4-bromophenyl group, 2-iodo Phenyl group, 3-iodophenyl group, 4-iodophenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2-ethylphenyl group, 3-ethylphenyl group, 4-ethylphenyl group 2-methoxyphenyl group, 3-methoxyphenyl group, 4-methoxyphenyl group, 2-ethoxyphenyl group, 3-ethoxyphenyl group 4-ethoxyphenyl group, 2- (dimethylamino) phenyl group, 3- (dimethylamino) phenyl group, 4- (dimethylamino) phenyl group, phenoxy group, 2-methylphenoxy group, 3-methylphenoxy group, 4 -Methylphenoxy group, 2-ethylphenoxy group, 3-ethylphenoxy group, 4-ethylphenoxy group, 2-methoxyphenoxy group, 3-methoxyphenoxy group, 4-methoxyphenoxy group, 2-ethoxyphenoxy group, 3-ethoxy Examples include phenoxy group, 4-ethoxyphenoxy group, 2- (dimethylamino) phenoxy group, 3- (dimethylamino) phenoxy group, 4- (dimethylamino) phenoxy group and the like. Of these, a phenyl group is preferable.
Further, when the phenyl group represented by X is substituted, it is preferable that part or all of the hydrogen of the phenyl group is substituted with halogen, and it is more preferable that the phenyl group is substituted with fluorine.

In the formula (1), ^{R 5} and ^{R 6} represents an alkylene group having 0-6 carbon atoms. The case where R ⁵ and R ⁶ are “an alkylene group having 0 carbon atoms” means that when the nitrogen atom bonded to R ³ and the sulfonyl group is directly bonded to R ¹ , the nitrogen bonded to R ⁴ and the sulfonyl group It means a case where atoms are bonded directly to R ^2.
In the formula (1), the alkylene group represented by R ⁵ and R ^6, for example, methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group and the like. Of these, a methylene group and an ethylene group are preferable.

R ¹ and R ² , R ³ and R ⁴ , and R ⁵ and R ⁶ may be the same or different, but are preferably the same.

In the formula (1), the optionally substituted alkyl group represented by M is, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl. Group, t-butyl group, n-pentyl group, n-hexyl group and the like. Of these, a methyl group is preferable.
Further, when the alkyl group represented by M is substituted, it is preferable that part or all of the alkyl group is substituted with halogen, and more preferably substituted with fluorine.

The additive for non-aqueous electrolyte of the present invention is such that the obtained non-aqueous electrolyte exhibits a high discharge capacity retention ratio and a low internal resistance ratio. A compound represented by the formula (2), a compound represented by the following formula (3), a compound represented by the following formula (4), a compound represented by the following formula (5), and a formula represented by the following formula (6) A compound represented by the following formula (7), a compound represented by the following formula (8), a compound represented by the following formula (9), a compound represented by the following formula (10), and It preferably comprises at least one imide sulfonic acid amide compound selected from the group consisting of compounds represented by the following formula (11).

Examples of the method for producing the imide sulfonic acid amide compound according to the present invention include a method of reacting an amidosulfuric acid and chlorosulfuric acid with an amine in the presence of thionyl chloride.

The preferred lower limit of the lowest unoccupied molecular orbital (LUMO) energy of the imide sulfonic acid amide compound according to the present invention 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 imide sulfonic acid amide compound according to the present invention exhibits low LUMO energy that is susceptible to electrochemical reduction, the additive for a non-aqueous electrolyte of the present invention comprising the compound is used for a non-aqueous electrolyte secondary battery or the like. When added to a non-aqueous electrolyte used in an electricity storage device, stable SEI can be formed on the electrode surface to improve battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance. Further, since the imide sulfonic acid amide compound according to the present invention is stable against moisture and temperature changes, the additive for non-aqueous electrolyte of the present invention comprising the compound can be stored at room temperature for a long period of time. Is possible. 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 imide sulfonic acid amide compound represented by the formula (1)) is not particularly limited, but is preferably the 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
(Synthesis of imidodisulfuryl chloride)
A 500 mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel was charged with 217.0 g (1.8 mol) of thionyl chloride, and 58.3 g (0. 6 mol) was added dropwise over 2 hours, and then 75.5 g (0.7 mol) of chlorosulfuric acid was added dropwise over 2 hours. Subsequently, the mixture was stirred for 12 hours under reflux with heating, and then distilled off under reduced pressure to obtain 132 g of a crude product. The obtained crude product was fractionated by distillation under reduced pressure to obtain 124.5 g of imidodisulfuryl chloride. The yield of imidodisulfyl chloride was 97% with respect to amidosulfuric acid.

(Synthesis of imidosulfonic acid amide compound (compound 1))
In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 11.8 g (0.11 mol) of methylaniline, 14.1 g (0.14 mol) of triethylamine, and methyl t -80 g of butyl ether was charged and cooled to 0 ° C. Subsequently, 10.7 g (0.05 mol) of the obtained imidodisulfuryl chloride was dropped, the temperature was gradually raised to room temperature, and the mixture was stirred overnight. Methyl t-butyl ether was removed from the organic layer by distillation under reduced pressure. After adding 20 g of heptane and stirring for 1 hour under heating and refluxing, the mixture was cooled to room temperature to precipitate crystals. The obtained crystals were filtered and dried under reduced pressure to obtain 15.6 g (0.04 mol) of an imide sulfonic acid amide compound (Compound 1) represented by the formula (2). The yield of Compound 1 was 88% with respect to imidodisulfuryl chloride.

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte So that the content ratio of the compound 1 prepared as an additive for a non-aqueous electrolyte is 0.5% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

(Example 2)
In “Preparation of Nonaqueous Electrolyte”, a nonaqueous electrolyte was prepared in the same manner as in Example 1 except that the content ratio of Compound 1 was 1.0% by mass.

(Example 3)
(Synthesis of imidosulfonic acid amide compound (compound 2))
A 100 mL four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel was charged with 6 g (0.01 mol) of 15% butyllithium hexane solution and 10.0 g of tetrahydrofuran, and cooled to 0 ° C. Then, 1.5 g (0.01 mol) of diisopropylamine was added dropwise over 30 minutes. A solution prepared by dissolving Compound 1 obtained in the same manner as in Example 1 in 5.0 g (0.01 mol) of tetrahydrofuran was added dropwise over 2 hours and stirred for 10 hours. The precipitated crystals were filtered and dried under reduced pressure to obtain 4.2 g (0.01 mol) of an imide sulfonic acid amide compound (Compound 2) represented by the formula (3). The yield of Compound 2 with respect to Compound 1 was 83% (73% with respect to imidodisulfuryl chloride).

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte So that the content ratio of the compound 2 prepared as an additive for the non-aqueous electrolyte is 1.0% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

Example 4
(Synthesis of imidosulfonic acid amide compound (compound 3))
In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 13.3 g (0.11 mol) of methylbenzylamine, 14.1 g (0.14 mol) of triethylamine, and methyl 80 g of t-butyl ether was charged and cooled to 0 ° C. Subsequently, 10.7 g (0.05 mol) of imide disulfuryl chloride obtained in the same manner as in Example 1 was added dropwise, the temperature was gradually raised to room temperature, stirred overnight, and then 25 g of water was added. Liquid separation was performed, and methyl t-butyl ether was removed from the obtained organic layer by distillation under reduced pressure. After adding 20 g of heptane and stirring for 1 hour under heating and refluxing, the mixture was cooled to room temperature to precipitate crystals. The obtained crystals were filtered and dried under reduced pressure to obtain 17.3 g (0.05 mol) of an imide sulfonic acid amide compound (Compound 3) represented by the formula (4). The yield of Compound 3 was 90% with respect to imidodisulfuryl chloride.

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte So that the content ratio of the compound 3 prepared as an additive for the non-aqueous electrolyte is 1.0% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

(Example 5)
(Synthesis of imidosulfonic acid amide compound (compound 4))
A 100 mL four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel was charged with 6 g (0.01 mol) of 15% butyllithium hexane solution and 10.0 g of tetrahydrofuran, and cooled to 0 ° C. Then, 1.5 g (0.01 mol) of diisopropylamine was added dropwise over 30 minutes. A solution prepared by dissolving Compound 3 obtained in the same manner as in Example 4 in 5.4 g (0.01 mol) of tetrahydrofuran was added dropwise over 2 hours and stirred for 10 hours. The precipitated crystals were filtered and dried under reduced pressure to obtain 4.9 g (0.01 mol) of an imide sulfonic acid amide compound (Compound 4) represented by the formula (5). The yield of Compound 4 with respect to Compound 3 was 90% (81% with respect to imidodisulfuryl chloride).

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte So that the content ratio of the compound 4 prepared as an additive for the non-aqueous electrolyte is 1.0% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

(Example 6)
(Synthesis of imidosulfonic acid amide compound (compound 5))
In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 13.8 g (0.11 mol) of 4-fluoro-N-methylaniline and 14.1 g (0.14 mol) of triethylamine were added. ) And 80 g of methyl t-butyl ether were charged and cooled to 0 ° C. Subsequently, 10.7 g (0.05 mol) of imide disulfuryl chloride obtained in the same manner as in Example 1 was added dropwise, the temperature was gradually raised to room temperature, stirred overnight, and then 25 g of water was added. Liquid separation was performed, and methyl t-butyl ether was removed from the obtained organic layer by distillation under reduced pressure. After adding 20 g of heptane and stirring for 1 hour under heating and refluxing, the mixture was cooled to room temperature to precipitate crystals. The obtained crystals were filtered and dried under reduced pressure to obtain 16.4 g (0.04 mol) of an imide sulfonic acid amide compound (Compound 5) represented by the following formula (6). The yield of Compound 5 was 90% based on imidodisulfuryl chloride.

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte The compound 5 prepared as an additive for a non-aqueous electrolyte is 1.0% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

(Example 7)
(Synthesis of Imidosulfonic Acid Amide Compound (Compound 6))
A 100 mL four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel was charged with 6 g (0.01 mol) of 15% butyllithium hexane solution and 10.0 g of tetrahydrofuran, and cooled to 0 ° C. Then, 1.5 g (0.01 mol) of diisopropylamine was added dropwise over 30 minutes. A solution obtained by dissolving 5.5 g (0.01 mol) of the obtained compound 5 in tetrahydrofuran was added dropwise over 2 hours and stirred for 10 hours. The precipitated crystals were filtered and dried under reduced pressure to obtain 4.4 g (0.01 mol) of an imide sulfonic acid amide compound (Compound 6) represented by the formula (7). The yield of Compound 6 with respect to Compound 5 was 74% (67% with respect to imidodisulfuryl chloride).

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte So that the content ratio of the compound 6 prepared as the additive for the non-aqueous electrolyte is 1.0% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

(Example 8)
(Synthesis of imidosulfonic acid amide compound (compound 7))
In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 10.2 g (0.11 mol) of aniline, 14.1 g (0.14 mol) of triethylamine, and methyl t- 80 g of butyl ether was charged and cooled to 0 ° C. Subsequently, 10.7 g (0.05 mol) of imide disulfuryl chloride obtained in the same manner as in Example 1 was added dropwise, the temperature was gradually raised to room temperature, stirred overnight, and then 25 g of water was added. Liquid separation was performed, and methyl t-butyl ether was removed from the obtained organic layer by distillation under reduced pressure. After adding 20 g of heptane and stirring for 1 hour under heating and refluxing, the mixture was cooled to room temperature to precipitate crystals. The obtained crystals were filtered and dried under reduced pressure to obtain 13.1 g (0.04 mol) of an imide sulfonic acid amide compound (Compound 7) represented by the formula (8). The yield of compound 7 was 90% based on imidodisulfuryl chloride.

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte So that the content ratio of the compound 7 prepared as an additive for the non-aqueous electrolyte is 1.0% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

Example 9
(Synthesis of imidosulfonic acid amide compound (compound 8))
In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel, 21.7 g (0.11 mol) of dibenzylamine, 14.1 g (0.14 mol) of triethylamine, and methyl 80 g of t-butyl ether was charged and cooled to 0 ° C. Subsequently, 10.7 g (0.05 mol) of imide disulfuryl chloride obtained in the same manner as in Example 1 was added dropwise, the temperature was gradually raised to room temperature, stirred overnight, and then 25 g of water was added. Liquid separation was performed, and methyl t-butyl ether was removed from the obtained organic layer by distillation under reduced pressure. After adding 30 g of heptane and stirring for 1 hour under heating and refluxing, the mixture was cooled to room temperature to precipitate crystals. The obtained crystals were filtered and dried under reduced pressure to obtain 20.8 g (0.04 mol) of an imide sulfonic acid amide compound (Compound 8) represented by the formula (9). The yield of Compound 8 was 75% based on imidodisulfuryl chloride.

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte The compound 8 prepared as an additive for a non-aqueous electrolyte is 1.0% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

(Example 10)
(Synthesis of imidosulfonic acid amide compound (compound 9))
In a 200 mL four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel, 14.9 g (0.11 mol) of N-methylphenylethylamine, 14.1 g (0.14 mol) of triethylamine, and Then, 80 g of methyl t-butyl ether was charged and cooled to 0 ° C. Subsequently, 10.7 g (0.05 mol) of imide disulfuryl chloride obtained in the same manner as in Example 1 was added dropwise, the temperature was gradually raised to room temperature, stirred overnight, and then 25 g of water was added. Liquid separation was performed, and methyl t-butyl ether was removed from the obtained organic layer by distillation under reduced pressure. After adding 20 g of heptane and stirring for 1 hour under heating and refluxing, the mixture was cooled to room temperature to precipitate crystals. The obtained crystals were filtered and dried under reduced pressure to obtain 16.9 g (0.04 mol) of an imide sulfonic acid amide compound (Compound 9) represented by the formula (10). The yield of compound 9 was 82% based on imidodisulfuryl chloride.

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte The compound 9 prepared as an additive for a non-aqueous electrolyte is 1.0% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

(Example 11)
(Synthesis of Imidosulfonic Acid Amide Compound (Compound 10))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 1.1 g (0.03 mol) of 60% pure sodium hydride and 15 g of tetrahydrofuran, and cooled to 0 ° C. Subsequently, a solution in which 3.6 g (0.01 mol) of Compound 1 was dissolved in 10 g of tetrahydrofuran was added dropwise over 2 hours. After stirring for 1 hour, 2.8 g (0.02 mol) of iodomethane was added over 30 minutes. It was dripped. After gradually raising the temperature to room temperature and stirring overnight, 25 g of water was added for liquid separation, and tetrahydrofuran was removed from the resulting organic layer by distillation under reduced pressure. After adding 10 g of heptane and 3 g of toluene and stirring for 1 hour under heating and refluxing, the mixture was cooled to room temperature to precipitate crystals. The obtained crystals were filtered and dried under reduced pressure to obtain 2.1 g (0.01 mol) of an imide sulfonic acid amide compound (Compound 10) represented by the formula (11). The yield of Compound 10 was 58% with respect to Compound 1 (51% with respect to imidodisulfuryl chloride).

(Preparation of non-aqueous electrolyte)
In a mixed non-aqueous solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume composition ratio of EC: DEC = 30: 70, a concentration of 1.0 mol / L of LiPF ₆ as an electrolyte So that the content ratio of the compound 10 prepared as the additive for the non-aqueous electrolyte is 1.0% by mass with respect to the total weight of the solution composed of the mixed non-aqueous solvent and the electrolyte. This was added to prepare a non-aqueous electrolyte.

(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 imide sulfonic acid amide compounds (compounds 1 to 10) according to the present invention is from about −0.40 eV to about −0.67 eV showing a negative value, and these imide sulfonic acid amide compounds are It can be seen that it has low LUMO energy. Therefore, when the compounds 1 to 10 are used as an additive for a non-aqueous electrolyte in an electricity storage device such as a non-aqueous electrolyte secondary battery, the solvent of the non-aqueous electrolyte (for example, cyclic carbonate or chain carbonate: about LUMO energy) Electrochemical reduction of compounds 1 to 10 occurs prior to 1.2 eV), and SEI is formed on the electrode, so that decomposition of the solvent in the electrolyte 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 imidosulfonic acid amide 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 an electricity storage device such as a nonaqueous electrolyte secondary 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 non-aqueous electrolyte obtained in each example and each comparative example, 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 imide sulfonic acid amide compound of the example was compared with the cylindrical secondary battery using the non-aqueous electrolyte of the comparative example. It can be seen that a stable SEI is formed with respect to the charge / discharge cycle. In addition, the non-aqueous electrolyte using the imide sulfonic acid amide compound of the example maintains a low internal resistance ratio compared to the non-aqueous electrolyte of the comparative example, and increases the internal resistance due to the cycle. It turns out that it can suppress.

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)

A non-aqueous electrolyte additive comprising an imide sulfonic acid amide compound represented by the following formula (1).

In formula (1), R ¹ and R ² each independently represent an optionally substituted phenyl group. R ³ and R ⁴ are each independently hydrogen, an optionally substituted alkyl group having 1 to 6 carbon atoms, or —R ⁷ X (R ⁷ is an optionally substituted carbon atom having 1 to 6 carbon atoms). And X represents an optionally substituted phenyl group or phenoxy group). R ⁵ and R ⁶ are each independently an optionally substituted alkylene group having 0 to 6 carbon atoms. M represents hydrogen, lithium, or an alkyl group having 1 to 6 carbon atoms. A compound represented by the following formula (2), a compound represented by the following formula (3), a compound represented by the following formula (4), a compound represented by the following formula (5), and the following formula (6) A compound represented by the following formula (7), a compound represented by the following formula (8), a compound represented by the following formula (9), a compound represented by the following formula (10), and The additive for non-aqueous electrolyte according to claim 1, comprising at least one imide sulfonic acid amide compound selected from the group consisting of compounds represented by the following formula (11).

The additive for non-aqueous electrolyte according to claim 1 or 2, wherein the imidosulfonic acid amide 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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