JP5877109B2 - Phosphorus-containing sulfonic acid ester compound, additive for non-aqueous electrolyte, non-aqueous electrolyte, and electricity storage device - Google Patents

Description

The present invention relates to a novel phosphorus-containing sulfonic acid ester compound. In addition, the present invention, when used in an electricity storage device such as a non-aqueous electrolyte secondary battery or an electric double layer capacitor, forms a stable solid electrolyte interface on the electrode surface, thereby providing cycle characteristics, charge / discharge capacity, and internal resistance. The present invention relates to an additive for a non-aqueous electrolyte that can improve battery characteristics such as the above. Furthermore, the present invention 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, as interest in solving environmental problems and realizing a sustainable recycling society increases, research on power storage devices such as non-aqueous electrolyte secondary batteries and electric double layer capacitors has been extensively conducted. 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 solvent or the like in 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 power storage devices such as non-aqueous electrolyte secondary batteries when charging / discharging cycles are repeated, and improving battery characteristics, storage characteristics, load characteristics, etc. It has been.

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 disclose an electrolytic solution containing vinylene carbonate and vinyl ethylene carbonate, and Patent Documents 14 and 15 disclose an electrolytic solution containing 1,3-propane sultone and 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

The performance of SEI formed on the electrode surface varies depending on the additive used, and is deeply involved in many battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance. However, when conventional additives are used, it has been difficult to form SEI with sufficient performance and to keep its battery characteristics high over a long period of time.
For example, an electrolytic solution using a vinylene carbonate compound or a sultone compound such as 1,3-propane sultone described in Patent Documents 10 to 15 as an additive causes electrochemical reductive decomposition on the negative electrode surface. The generated SEI can suppress irreversible capacity reduction. However, although SEI formed by these additives is excellent in the performance of protecting the electrode, the performance of lowering the internal resistance is small because of the low ion conductivity of lithium ions. Furthermore, the formed SEI does not have the strength to withstand long-term use, and the SEI decomposes during use or the SEI cracks, exposing the negative electrode surface and causing decomposition of the electrolyte solvent. There was a problem that the battery characteristics deteriorated.

As described above, the conventional additive for non-aqueous electrolyte does not have sufficient performance over a long period of time in performance of protecting the electrode or reducing internal resistance, and there is room for improvement. . That is, a novel electrolyte additive that improves the battery characteristics of non-aqueous electrolyte secondary batteries, etc., by forming SEI that is stable on the electrode surface and that improves cycle characteristics, charge / discharge capacity, internal resistance, etc. Development of was desired.
An object of the present invention is to provide a novel phosphorus-containing sulfonic acid ester compound that is suitably used for an additive for a non-aqueous electrolyte. The present invention also provides battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance by forming stable SEI on the electrode surface when the compound is used in an electricity storage device such as a non-aqueous electrolyte secondary battery. An object of the present invention is to provide an additive for a non-aqueous electrolyte solution that can improve the above. Furthermore, an 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 a phosphorus-containing sulfonic acid ester compound represented by the following formula (1).

In formula (1), R ¹ and R ² each independently represent an optionally substituted alkyl group having 1 to 6 carbon atoms or an optionally substituted phenyl group. R ³ and R ⁴ each independently represent an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted phenyl group, or an optionally substituted phenoxy group, or , R ³ and R ⁴ represent a common group, an optionally substituted alkylene group having 1 to 6 carbon atoms, or an optionally substituted phenylene group. Y represents a hydrogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted phenyl group, or a halogen atom.
The present invention is described in detail below.

As an index of the adaptability of non-aqueous electrolyte additives to electrochemical reduction in electrodes of non-aqueous electrolyte secondary batteries and the like, for example, “Geun-Chang, Hyung-Jin Kim, Seung-ll Yu, Song-Hui Jun, Jong-Wook Choi, Myung-Hwan Kim.Journal of The Electrochemical Society, 147, 12, 4391 (2000) "includes the LUMO (minimum unoccupied molecular orbital) energy of the compound constituting the additive for non-aqueous electrolytes. A method using a plurality of energy levels has been reported. In such a document, a compound having a lower LUMO energy is an electron acceptor that is more excellent, and is a non-aqueous electrolyte additive that can form a stable SEI on the surface of an electrode such as a non-aqueous electrolyte secondary battery. It is supposed to be. Therefore, by measuring the LUMO energy of a compound, it is possible to easily evaluate whether the compound has the ability to form stable SEI on the electrode surface of a nonaqueous electrolyte secondary battery or the like. Is now a very useful tool.
The present inventors have found that the phosphorus-containing sulfonic acid ester compound represented by the formula (1) exhibits low LUMO energy that is susceptible to electrochemical reduction and is chemically stable. Therefore, the present inventors use the non-aqueous electrolyte additive comprising the phosphorus-containing sulfonic acid ester compound as a non-aqueous electrolyte, and further use the non-aqueous electrolyte for an electricity storage device such as a non-aqueous electrolyte secondary battery. In such a case, it has been found that stable SEI can be formed on the electrode surface to improve battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance, and the present invention has been completed.

The present invention is a phosphorus-containing sulfonic acid ester compound represented by the formula (1).
In the formula (1), R ¹ and R ² each independently represent an optionally substituted alkyl group having 1 to 6 carbon atoms or an optionally substituted phenyl group.
In the formula (1), if at least one of R ¹ and R ² is an alkyl group, the carbon number of the alkyl group represented by R ¹ and R ² is 7 or more, solubility in the nonaqueous solvent May decrease. A preferred upper limit of the carbon number of the alkyl group represented by R ¹ and R ² is 3.

In the formula (1), examples of the alkyl group having 1 to 6 carbon atoms represented by R ¹ and R ² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, 1- Examples thereof include a methylethyl group, an n-pentyl group, and an n-hexyl group. Of these, an ethyl group is preferable.
In addition, when the alkyl group represented by R ¹ and R ² is substituted, it is preferably substituted with a halogen atom, and more preferably substituted with a fluorine atom.

In the formula (1), when at least one of R ¹ and R ² is an optionally substituted phenyl group, examples of the optionally substituted phenyl group include a phenyl group and a 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, 2-fluorophenyl group, 3-fluorophenyl group, 4-fluorophenyl group, 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group 2-bromophenyl group, 3-bromophenyl group, a 4-bromophenyl group. Among these, a phenyl group, a 2-fluorophenyl group, a 3-fluorophenyl group, and a 4-fluorophenyl group are preferable because they exhibit low LUMO energy that is susceptible to electrochemical reduction.

In said formula (1), R < ³ > and R < ⁴ > are respectively independent, the C1-C6 alkyl group which may be substituted, the phenyl group which may be substituted, or may be substituted. A phenoxy group, or an optionally substituted alkylene group having 1 to 6 carbon atoms or an optionally substituted phenylene group in which R ³ and R ⁴ are a common group to form a cyclic structure. Show.

In the formula (1), when at least one alkyl group which may be substituted by R ³ and R ^4, if the number of carbon atoms in the alkyl group represented by R ³ and R ⁴ is 7 or more, non-aqueous There is a possibility that the solubility in a solvent may decrease. A preferred upper limit of the number of carbon atoms of the alkyl group represented by R ³ and R ⁴ is 3.

In the formula (1), examples of the alkyl group having 1 to 6 carbon atoms represented by R ³ and R ⁴ include the same as those described for R ¹ and R ² .
Further, when the alkyl group represented by R ³ and R ⁴ is substituted, it is preferably substituted with a halogen atom, and more preferably substituted with a fluorine atom.

In the formula (1), when at least one of R ³ and R ⁴ is an optionally substituted phenyl group, the optionally substituted phenyl group is the one described for R ¹ and R ² The same thing is mentioned. Among these, a phenyl group, a 2-fluorophenyl group, a 3-fluorophenyl group, and a 4-fluorophenyl group are preferable because they exhibit low LUMO energy that is susceptible to electrochemical reduction.

In the formula (1), when at least one of R ³ and R ⁴ is an optionally substituted phenoxy group, examples of the optionally substituted phenoxy group include a phenoxy group and a 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- (dimethylamino) phenoxy group, 3- (dimethylamino) phenoxy group, 4- (dimethylamino) phenoxy group, 2-fluorophenoxy group, 3-fluorophenoxy group, 4-fluorophenoxy group, 2-chlorophenoxy group 3-chlorophenoxy group, 4-chlorophenoxy group, 2-bromophenoxy group, 3-bromophenoxy group, 4-bromophenoxy group. Among these, a phenoxy group, a 2-fluorophenoxy group, a 3-fluorophenoxy group, and a 4-fluorophenoxy group are preferable because they exhibit low LUMO energy that is easily subjected to electrochemical reduction.

In the formula (1), when R ³ and R ⁴ are a common group, which is an optionally substituted alkylene group having 1 to 6 carbon atoms, the alkylene group has 7 or more carbon atoms. And there exists a possibility that the solubility to a non-aqueous solvent may fall. The upper limit of carbon number of the alkylene group is preferably 2.

Examples of the alkylene group include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, a 1-methylethylene group, a 1-ethylethylene group, an n-pentylene group, and an n-hexylene group. Etc. Of these, a methylene group is preferable.
Further, when the alkylene group is substituted, it is preferably substituted with a halogen atom, and more preferably substituted with a fluorine atom.

In the above formula (1), when R ³ and R ⁴ are a common group to form a substituted phenylene group, it is preferably substituted with a halogen atom, and preferably substituted with a fluorine atom. More preferred.

In said formula (1), Y shows a hydrogen atom, the C1-C6 alkyl group which may be substituted, the phenyl group which may be substituted, or a halogen atom.
Examples of the alkyl group having 1 to 6 carbon atoms represented by Y include the same as those described for R ¹ and R ² .
When the alkyl group represented by Y is substituted, it is preferably substituted with a halogen atom, and more preferably substituted with a fluorine atom.

In the formula (1), when Y is an optionally substituted phenyl group, examples of the optionally substituted phenyl group include the same as those described for R ¹ and R ^2. . Among these, a phenyl group, a 2-fluorophenyl group, a 3-fluorophenyl group, and a 4-fluorophenyl group are preferable because they exhibit low LUMO energy that is susceptible to electrochemical reduction.

In the formula (1), when Y is a halogen atom, the halogen atom is preferably a fluorine atom.

The phosphorus-containing sulfonic acid ester compound represented by the formula (1) is particularly chemically stable and can prevent deterioration of the battery due to decomposition of the electrolytic solution when SEI is formed. And the phosphorus containing sulfonate compound represented by following formula (2), (3) is preferable by showing a low LUMO energy.

In the formula ^(2), R 1, ^{R 2} and, Y is, ^R 1, ^{R 2} in each of the formulas (1), and show the same atom or group as Y.

In the formula ^(3), R 1, ^{R 2} and, Y is, ^R 1, ^{R 2} in each of the formulas (1), and show the same atom or group as Y. R ⁵ and R ⁶ each independently represent an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted phenyl group, or an optionally substituted phenoxy group.

Examples of the optionally substituted alkyl group having 1 to 6 carbon atoms, the optionally substituted phenyl group, and the optionally substituted phenoxy group in R ⁵ and R ⁶ of the formula (3) include The thing similar to what was described about R < ³ > and R < ⁴ > in Formula (1) is mentioned.

As a method for producing the phosphorus-containing sulfonic acid ester compound represented by the formula (1), for example, a product obtained by reacting bromoacetic acid with trialkyl phosphite and further reacting with chlorosulfonic acid And a method of reacting bromoacetic acid with trialkyl phosphite and then reacting with chlorosulfonic acid and an alcohol.

For example, in the case of producing a phosphorus-containing sulfonic acid ester compound in which R ¹ is an ethyl group, R ² is an ethyl group, and Y is hydrogen in the formula (2), bromoacetic acid and triethyl phosphite are reacted. Then, a method of hydrolyzing the product obtained by reacting with chlorosulfonic acid and further reacting with paraformaldehyde can be used.
In the case where a phosphorus-containing sulfonic acid ester compound in which R ¹ is an ethyl group, R ² is an ethyl group, R ⁵ is an ethyl group, R ⁶ is an ethyl group, and Y is hydrogen in the formula (3) is produced. Can be obtained by reacting bromoacetic acid with triethyl phosphite and then reacting with chlorosulfonic acid with ethanol.

The additive for non-aqueous electrolytes comprising the phosphorus-containing sulfonic acid ester compound of the present invention is also one aspect of the present invention. The phosphorus-containing sulfonic acid ester compound of the present invention is chemically stable, can prevent deterioration of the battery due to decomposition of the electrolytic solution and the like when SEI is formed, and is easily subjected to electrochemical reduction. LUMO energy is shown.
Furthermore, by using the additive for a non-aqueous electrolyte comprising the phosphorus-containing sulfonic acid ester compound of the present invention, for example, when LiPF ₆ is used as the electrolyte, PF ₅ generated by the decomposition reaction of LiPF ₆ is attributed. It is considered that there is an effect of suppressing generation of gas and the like. The reason is not clear, but PF ₅ is coordinated with> P═O of the phosphorus-containing sulfonate compound of the present invention, so that activation of PF ₅ can be suppressed and battery characteristics can be further improved. It is considered possible.
Further, the additive for non-aqueous electrolyte of the present invention comprising the compound has a stable SEI on the electrode surface when used in an electricity storage device such as a non-aqueous electrolyte secondary battery contained in the non-aqueous electrolyte. It can be formed to improve battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance.

The non-aqueous electrolyte containing the additive for non-aqueous electrolyte, non-aqueous solvent, and 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 phosphorus-containing sulfonic acid ester compound represented by the formula (1)) is not particularly limited, but is preferable. The lower limit is 0.005% by mass, and the preferred upper limit is 10% by mass. When the content of the additive for non-aqueous electrolyte of the present invention is less than 0.005% by mass, stable SEI is sufficiently obtained by an electrochemical reaction on the electrode surface when used in a non-aqueous electrolyte secondary battery or the like. May not be formed. 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 conductivity and the like of the electrolyte cannot be sufficiently ensured, and there is a possibility that the charge / discharge characteristics and the like may be hindered when used for an electricity storage device such as a non-aqueous electrolyte secondary battery. The more preferable lower limit of the content of the additive for non-aqueous electrolyte of the present invention is 0.01% by mass.

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, methyl propionate, and propion. Aliphatic carboxylic acid esters such as ethyl acetate, methyl butyrate, methyl isobutyrate and methyl trimethylacetate, lactones such as γ-butyrolactone, lactams such as ε-caprolactam and N-methylpyrrolidone, tetrahydrofuran, 2-methyltetrahydrofuran, Cyclic ethers such as tetrahydropyran and 1,3-dioxolane, chain ethers such as 1,2-ethoxyethane and ethoxymethoxyethane, sulfones such as sulfolane, 4-fluoro-1,3-dioxolan-2-one 4-chloro-1,3-di And halogen derivatives such as oxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one. These nonaqueous solvents may be used alone or in combination of two or more.

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 them, it may contain at least one selected from the group consisting of cyclic carbonates, chain carbonates, aliphatic carboxylic acid esters, lactones, lactams, cyclic ethers, chain ethers, sulfones, and halogen derivatives thereof. preferable. Among these, it is more preferable to mix one or more cyclic carbonates and chain carbonates.
The non-aqueous solvent is preferably used for non-aqueous electrolyte secondary batteries such as lithium ion batteries and electric double layer capacitors such as lithium ion capacitors.

The electrolyte is preferably a lithium salt that serves as a source of lithium ions. Among _{them, LiAlCl 4, LiBF 4, LiPF} 6, LiClO 4, LiAsF 6, and is preferably at least one selected from the group consisting of LiSbF _6, more preferably LiBF 4, it is LiPF _6, LiPF ₆ is more preferred. These electrolytes may be used alone or in combination of two or more. When LiPF ₆ is used, as the non-aqueous solvent, it is preferable to mix one or more cyclic carbonates and chain carbonates, and it is more preferable to mix ethylene carbonate and diethyl carbonate.

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 electrolyte is charged when used for an electricity storage device such as a non-aqueous electrolyte secondary battery. There is a risk of disturbing the discharge characteristics. If 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 ensured. When used in an electricity storage device such as a water electrolyte secondary battery, the charge / discharge characteristics may be hindered. 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 a non-aqueous electrolyte secondary battery and an electric double layer capacitor. Of these, lithium ion batteries and lithium ion capacitors are preferred.
FIG. 1 is a cross-sectional view schematically showing an example of a non-aqueous electrolyte secondary battery according to the present invention.
In FIG. 1, a nonaqueous electrolyte secondary battery 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 current collector 5 on one surface side. It has a negative electrode plate 7 provided with a negative electrode active material layer 6. 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 nonaqueous electrolyte secondary battery according to 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 non-aqueous electrolyte secondary battery according to the present invention, a lithium-containing composite oxide is preferably used as the positive electrode active material used for the positive electrode active material layer 3. For example, LiMnO ₂ , LiFeO ₂ , LiCoO ₂ , LiMn ₂ O ₄ , Li ₂ FeSiO ₄ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , and lithium-containing composite oxides such as LiFePO ₄ .

In the non-aqueous electrolyte secondary battery according to 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 non-aqueous electrolyte secondary battery according to the present invention, as the separator 9, for example, a porous film made of polyethylene, polypropylene, fluororesin, or the like can be used. In the present embodiment, the non-aqueous electrolyte secondary battery is exemplified, but the present invention is not limited to this, and the present invention can also be applied to other electric storage devices such as electric double layer capacitors.

According to the present invention, a novel phosphorus-containing sulfonic acid ester compound can be provided. In addition, according to the present invention, when used in an electricity storage device such as a non-aqueous electrolyte secondary battery, a stable SEI is formed on the electrode surface to provide battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance. An additive for non-aqueous electrolyte that can be improved can be provided. Furthermore, according to the present invention, it is possible to provide a non-aqueous electrolyte using the non-aqueous electrolyte additive and an electricity storage device using the non-aqueous electrolyte.

It is sectional drawing which showed typically an example of the nonaqueous electrolyte secondary battery 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 phosphorus-containing sulfonic acid ester compound (Compound 1) in which R ¹ in Formula (2) is an ethyl group, R ² is an ethyl group, and Y is hydrogen)
A 200 mL four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel is charged with 13.9 g (0.1 mol) of bromoacetic acid and 70.0 g of dimethoxyethane and mixed with 20.0 g of dimethoxyethane. 16.6 g (0.1 mol) of triethyl phosphite was dropped at 0 ° C. over 2 hours. The temperature was gradually raised to room temperature and stirred overnight, then washed with water and saturated brine, and then dimethoxyethane was distilled off to obtain 30 g of a reaction product.
Next, 23.3 g (0.2 mol) of chlorosulfonic acid mixed with 46 g of phosphoryl chloride was charged into a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel. 30 g of the reaction product obtained in 1 was added dropwise over 1 hour. Then, it heated up to 100 degreeC over 2 hours, and stirred at the same temperature for 20 hours. Thereafter, phosphoryl chloride was removed by distillation under normal pressure, and then vacuum distillation (2 torr, 160 ° C.) was performed to obtain 25 g of an oily reaction product.
Next, 50 g of water was added to 25 g of the obtained oily reaction product, and the mixture was stirred at 100 ° C. for 12 hours. After completion of the reaction, water was removed by distillation under reduced pressure to obtain 20 g of a reaction product. Subsequently, 120 g of sulfolane was added to 20 g of the obtained reaction solution, and the temperature was raised to 100 ° C. Thereafter, 28 g (0.2 mol) of phosphorus oxide and 6 g (0.2 mol) of paraformaldehyde were alternately added, and the temperature was kept while stirring for 10 hours. After completion of the reaction, the mixture was cooled to room temperature, 30 g of water and 100 g of acetonitrile were added, and liquid separation was performed. Acetonitrile was removed by distillation under reduced pressure, followed by cooling to 0 ° C., and 160 g of water was added dropwise. The precipitated crystals are filtered, washed with hexane, and dried to obtain 6 g of a phosphorus-containing sulfonic acid ester compound (Compound 1) in which R ¹ in Formula (2) is an ethyl group, R ² is an ethyl group, and Y is hydrogen. Acquired. The yield of Compound 1 was 19% based on bromoacetic acid.

(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)
(Preparation of phosphorus-containing sulfonic acid ester compound (compound 2) in which R ¹ in formula (2) is a propyl group, R ² is a propyl group, and Y is hydrogen)
R ¹ is a propyl group in the same manner as in Example 2 except that 20.8 g (0.1 mol) of tripropyl phosphite was used instead of 16.6 g (0.1 mol) of triethyl phosphite. Then, 8 g of a phosphorus-containing sulfonic acid ester compound (Compound 2) in which R ² is a propyl group and Y is hydrogen was obtained. The yield of compound 2 was 23% based on bromoacetic acid.

(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
(Preparation of phosphorus-containing sulfonic acid ester compound (Compound 3) in which R ¹ in Formula (3) is an ethyl group, R ² is an ethyl group, R ⁵ is an ethyl group, R ⁶ is an ethyl group, and Y is hydrogen)
A 200 mL four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel is charged with 13.9 g (0.1 mol) of bromoacetic acid and 70.0 g of dimethoxyethane and mixed with 20.0 g of dimethoxyethane. 16.6 g (0.1 mol) of triethyl phosphite was dropped at 0 ° C. over 2 hours. The temperature was gradually raised to room temperature and stirred overnight, then washed with water and saturated brine, and then dimethoxyethane was distilled off to obtain 30 g of a reaction product.
Next, 23.3 g (0.2 mol) of chlorosulfonic acid mixed with 46 g of phosphoryl chloride was added to a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel over 1 hour. Then, 30 g of the reaction product obtained above was added dropwise over 1 hour. Then, it heated up to 100 degreeC over 2 hours, and stirred at the same temperature for 20 hours. Thereafter, phosphoryl chloride was removed by distillation under normal pressure, and then vacuum distillation (2 torr, 160 ° C.) was performed to obtain 25 g of an oily reaction product.
Next, 70 g of dimethoxyethane and 13.8 g (0.3 mol) of ethanol were charged into a 200 mL four-necked flask and cooled to 0 ° C. 25 g of the oily reaction product obtained above was added dropwise thereto over 2 hours, and then 41 g (0.4 mol) of triethylamine was added dropwise over 2 hours. Stirring was further continued for 10 hours, and after completion of the reaction, the reaction solution was filtered to remove inorganic salts, and then 100 g of toluene and 25 g of water were added for liquid separation. Removed. Subsequently, the mixture was cooled to 0 ° C., and 40 g of methanol was added dropwise over 3 hours to precipitate crystals. After filtering the crystals and drying under reduced pressure, a phosphorus-containing sulfonate compound (compound 3) in which R ¹ is an ethyl group, R ² is an ethyl group, R ⁵ is an ethyl group, R ⁶ is an ethyl group, and Y is hydrogen. ) 10 g was obtained. The yield of compound 3 was 26% based on bromoacetic acid.

(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)
(Preparation of phosphorus-containing sulfonic acid ester compound (Compound 4) in which R ¹ in Formula (3) is an ethyl group, R ² is an ethyl group, R ⁵ is a phenyl group, R ⁶ is a phenyl group, and Y is hydrogen)
In the same manner as in Example 4 except that 28.2 g (0.3 mol) of phenol was used instead of 13.8 g (0.3 mol) of ethanol, R ¹ was an ethyl group, R ² was an ethyl group, 8 g of a phosphorus-containing sulfonic acid ester compound (Compound 4) in which R ⁵ is a phenyl group, R ⁶ is a phenyl group, and Y is hydrogen was obtained. The yield of compound 4 was 18% based on bromoacetic acid.

(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.

(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 non-aqueous electrolyte was prepared in the same manner as in Example 2 except that 1,3-propane sultone was used in place of Compound 1.

(Comparative Example 3)
A non-aqueous electrolyte was prepared in the same manner as in Example 2 except that vinylene carbonate (VC) was used in place 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 used in place 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 to 4 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 the LUMO energies of the compounds 1 to 4 obtained by the orbit calculation.

From Table 1, the LUMO energy of the phosphorus-containing sulfonic acid ester compounds (compounds 1 to 4) represented by the formula (1) is about −0.21 eV to about −0.88 eV showing a negative value. It can be seen that these phosphorus-containing sulfonate compounds related to the non-aqueous electrolyte additive have low LUMO energy. Therefore, when the compounds 1 to 4 are used as an additive for a non-aqueous electrolyte in a power 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 4 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.
From the above, the phosphorus-containing sulfonic acid ester compound represented by the formula (1) according to the additive for non-aqueous electrolyte of the present invention has a sufficiently low LUMO energy, such as a non-aqueous electrolyte secondary battery. It shows that it is effective as a novel non-aqueous electrolyte additive that forms stable SEI on the electrode of the electricity storage device.

(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)
For each cylindrical secondary battery using the non-aqueous electrolyte obtained in each example and each comparative example, at 25 ° C., the charge rate was 0.3 C, the discharge rate was 0.3 C, and the charge end voltage was The charge / discharge cycle test was conducted at 4.2 V and a discharge end voltage of 2.5 V. 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 phosphorus-containing sulfonic acid ester compound of the example is compared with the cylindrical secondary battery using the non-aqueous electrolyte of the comparative example. It can be seen that the discharge capacity retention rate during the test is high. Therefore, when the non-aqueous electrolyte containing the non-aqueous electrolyte additive comprising the phosphorus-containing sulfonic acid ester compound of the example was used for a non-aqueous electrolyte secondary battery or the like, the non-aqueous electrolyte of the comparative example was used. Compared with the case, it turns out that SEI stable with respect to charging / discharging cycles is formed on the electrode surface of a nonaqueous electrolyte secondary battery or the like. In addition, the non-aqueous electrolyte using the silylsulfonic acid ester compound of the example can maintain a low internal resistance ratio as compared with the non-aqueous electrolyte of the comparative example, and the internal resistance due to the cycle can be maintained. It can be seen that the increase can be suppressed.

According to the present invention, a novel phosphorus-containing sulfonic acid ester compound can be provided. In addition, according to the present invention, when used in an electricity storage device such as a non-aqueous electrolyte secondary battery, a stable SEI is formed on the electrode surface to provide battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance. An additive for non-aqueous electrolyte that can be improved can be provided. Furthermore, according to the present invention, it is possible to provide a non-aqueous electrolyte using the non-aqueous electrolyte additive and an electricity storage device using the non-aqueous electrolyte.

DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte secondary battery 2 Positive electrode collector 3 Positive electrode active material layer 4 Positive electrode plate 5 Negative electrode collector 6 Negative electrode active material layer 7 Negative electrode plate 8 Nonaqueous electrolyte 9 Separator

Claims (12)

A phosphorus-containing sulfonic acid ester compound represented by the following formula (1):

In formula (1), R ¹ and R ² each independently represent an optionally substituted alkyl group having 1 to 6 carbon atoms or an optionally substituted phenyl group. R ³ and R ⁴ each independently represent an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted phenyl group, or an optionally substituted phenoxy group, or , R ³ and R ⁴ represent a common group, an optionally substituted alkylene group having 1 to 6 carbon atoms, or an optionally substituted phenylene group. Y represents a hydrogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted phenyl group, or a halogen atom. The phosphorus-containing sulfonate compound according to claim 1, which is represented by the following formula (2).

In formula (2), R ¹ , R ² , and Y represent the same atom or group as R ¹ , R ² , and Y in formula (1), respectively. The phosphorus-containing sulfonate compound according to claim 1, which is represented by the following formula (3).

In formula (3), R ¹ , R ² , and Y represent the same atom or group as R ¹ , R ² , and Y in formula (1), respectively. R ⁵ and R ⁶ each independently represent an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted phenyl group, or an optionally substituted phenoxy group. A non-aqueous electrolyte additive comprising the phosphorus-containing sulfonic acid ester compound according to claim 1, 2 or 3. A non-aqueous electrolyte comprising the additive for non-aqueous electrolyte according to claim 4, a non-aqueous solvent, and an electrolyte. The nonaqueous electrolytic solution according to claim 5, 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, sulfones, and halogen derivatives thereof. The non-aqueous electrolyte according to claim 6. The non-aqueous electrolyte according to claim 5, 6 or 7, 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 8, 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 5, 6, 7, 8, or 9, a positive electrode, and a negative electrode. The electrical storage device of Claim 10 whose electrical storage device is a lithium ion battery. The electrical storage device of Claim 10 whose electrical storage device is a lithium ion capacitor.

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