JP5953146B2 - Non-aqueous electrolyte additive, non-aqueous electrolyte, and electricity storage device - Google Patents

Description

The present invention is excellent in storage stability, and when used in an electricity storage device such as a non-aqueous electrolyte secondary battery or an electric double layer capacitor, a stable solid electrolyte interface is formed on the electrode surface, and cycle characteristics, charge / discharge The present invention relates to an additive for non-aqueous electrolyte that can improve battery characteristics such as capacity and internal resistance. The present invention also relates to a non-aqueous electrolyte containing the additive for non-aqueous electrolyte, 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 has increased, research on energy storage devices such as non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, and electric double layer capacitors, has become extensive. Has been done. 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.

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

As an index of the adaptability of the non-aqueous electrolyte additive to the electrochemical reduction at the electrode of the non-aqueous electrolyte secondary battery, 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) "describes the LUMO (minimum unoccupied molecular orbital) energy of a compound constituting a non-aqueous electrolyte additive. Methods using energy levels have 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 can be easily evaluated whether the compound has the ability to form a stable SEI on the electrode surface of an electricity storage device such as a non-aqueous electrolyte secondary battery. This method is now a very useful tool.

On the other hand, the compounds disclosed in Patent Documents 1 to 9 have high LUMO energy, insufficient performance as an additive for non-aqueous electrolytes, and are chemically unstable even if the LUMO energy is low. There were some problems. In particular, although the disulfonic acid ester compound exhibits low LUMO energy, it has a low stability to moisture and easily deteriorates. Therefore, when it is stored for a long period of time, it is necessary to strictly control the moisture content and temperature. Further, for example, a heat resistance temperature of about 60 ° C. is generally required for a lithium ion battery and a heat resistance temperature of about 80 ° C. is required for a lithium ion capacitor. Improvement of the stability at high temperature was one of the important issues.

As described above, conventional additives for non-aqueous electrolytes have not obtained sufficient performance and have room for improvement. Therefore, it has been desired to develop a novel electrolyte additive that has excellent storage stability, forms stable SEI on the electrode surface, and improves battery characteristics of power storage devices such as non-aqueous electrolyte secondary batteries. .
The present invention is excellent in storage stability and, when used in a power storage device such as a non-aqueous electrolyte secondary battery, forms a stable SEI on the electrode surface to provide a battery having cycle characteristics, charge / discharge capacity, internal resistance, etc. An object of the present invention is to provide an additive for non-aqueous electrolyte that can improve characteristics. Another object of the present invention is to provide a non-aqueous electrolyte containing the non-aqueous electrolyte additive and an electricity storage device using the non-aqueous electrolyte.

The present invention is an additive for a non-aqueous electrolyte comprising a disulfonic acid amide compound represented by the following formula (1).

In formula (1), X ¹ and X ² are each independently an alkylene group having 1 to 6 carbon atoms, or a nitrogen atom which may have an oxygen atom or a substituent in the carbon chain or at the chain end. Or an alkylene group having 1 to 6 carbon atoms having a sulfur atom. _A represents _{C m H (2m-n)} Z n, m is an integer from 1 to 6, n is an integer of 0 to 12, Z is is optionally also be from 1 to 4 carbon atoms substituted An alkyl group, a silyl group, a phosphonic acid ester group, an acyl group, a cyano group, or a nitro group is shown.
The present invention is described in detail below.

The present inventors have found that the disulfonic acid amide 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 disulfonic acid amide compound as a non-aqueous electrolyte, and further use the non-aqueous electrolyte in a power storage device such as a non-aqueous electrolyte secondary battery. In addition, the inventors have 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 reason why the disulfonic acid amide compound represented by the formula (1) according to the present invention improves battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance as an additive for non-aqueous electrolytes is not clear. It seems like. The disulfonic acid amide compound represented by the above formula (1) has a cyclic amino group, and when subjected to electrochemical reduction, the cyclic amino group is opened, and polarities including N, S, O, etc. It is thought to form SEI containing a large number of groups. Such SEI containing a large number of polar groups including N, S, O and the like can exhibit excellent ionic conductivity, and thus is considered to be a very high performance SEI.

The present invention is an additive for a nonaqueous electrolytic solution comprising a disulfonic acid amide compound represented by the formula (1).

In the formula (1), X ¹ and X ² are each independently an alkylene group having 1 to 6 carbon atoms, or nitrogen that may have an oxygen atom or a substituent in the carbon chain or at the chain end. atoms, or an alkylene group having 1 to 6 carbon atoms and having a sulfur _atom, a is shows the _{C m H (2m-n)} Z n, m is an integer from 1 to 6, n represents 0 to 12 Z represents an optionally substituted alkyl group having 1 to 4 carbon atoms, silyl group, phosphonic acid ester group, acyl group, cyano group, or nitro group.

“Carbon chain of X ¹ and X ² ” in the carbon chain or at the chain end, an oxygen atom, a nitrogen atom which may have a substituent, or a C 1-6 alkylene group having a sulfur atom In the middle or chain end, an oxygen atom, a nitrogen atom which may have a substituent, or a C 1-6 alkylene group having a sulfur atom is the above-mentioned “C 1-6 alkylene group”. ”In the carbon chain or at the chain end, a nitrogen atom which may have a substituent or a group having a sulfur atom, for example, —O—CH ₂ —, —O— (CH ₂ ). _2- , —O— (CH ₂ ) ₃ —, —O— (CH ₂ ) ₄ —, —O— (CH ₂ ) ₅ —, —O— (CH ₂ ) ₆ —, —CH ₂ —O—CH _{2 -, - CH 2 -O- (} CH 2) 2 -, - CH 2 -O- (CH 2) 3 -, - _{CH 2 -O- (CH 2) 4} -, - CH 2 -O- (CH 2) 5 -, - (CH 2) 2 -O- (CH 2) 2 -, - (CH 2) 2 -O- (CH ₂ ) ₃ —, — (CH ₂ ) ₂ —O— (CH ₂ ) ₄ —, — (CH ₂ ) ₃ —O— (CH ₂ ) ₃ —, —N—CH ₂ —, —N— ( _{CH 2) 2 -, - N-} (CH 2) 3 -, - N- (CH 2) 4 -, - N- (CH 2) 5 -, - N- (CH 2) 6 -, - CH 2 - N—CH ₂ —, —CH ₂ —N— (CH ₂ ) ₂ —, —CH ₂ —N— (CH ₂ ) ₃ —, —CH ₂ —N— (CH ₂ ) ₄ —, —CH ₂ —N _{- (CH 2) 5 -,} - (CH 2) 2 -N- (CH 2) 2 -, - (CH 2) 2 -N- (CH 2) 3 -, - (CH 2) 2 -N- ( CH ₂ ) ₄ -,-(CH ₂ ) ₃ -N- (CH ₂ ) _3- , -N (CH ₃ ) -CH _2- , -N (CH ₃ )-(CH ₂ ) _2- , -N (CH ₃ )-(CH ₂ ) _{3 -, - N (CH 3)} - (CH 2) 4 -, - N (CH 3) - (CH 2) 5 -, - N (CH 3) - (CH 2) 6 -, - CH 2 -N ( _{CH 3) -CH 2 -, -} CH 2 -N (CH 3) - (CH 2) 2 -, - CH 2 -N (CH 3) - (CH 2) 3 -, - CH 2 -N (CH 3 _{) - (CH 2) 4 -} , - CH 2 -N (CH 3) - (CH 2) 5 -, - (CH 2) 2 -N (CH 3) - (CH 2) 2 -, - (CH 2 _{) 2 -N (CH 3) -} (CH 2) 3 -, - (CH 2) 2 -N (CH 3) - (CH 2) 4 -, - (CH 2) 3 -N (CH 3) - ( CH _{2) -, - S-CH 2 -} , - S- (CH 2) 2 -, - S- (CH 2) 3 -, - S- (CH 2) 4 -, - S- (CH 2) 5 -, - S— (CH ₂ ) ₆ —, —CH ₂ —S—CH ₂ —, —CH ₂ —S— (CH ₂ ) ₂ —, —CH ₂ —S— (CH ₂ ) ₃ —, —CH ₂ —S _{- (CH 2) 4 -,} - CH 2 -S- (CH 2) 5 -, - (CH 2) 2 -S- (CH 2) 2 -, - (CH 2) 2 -S- (CH 2) _{3 -, - (CH 2)} 2 -S- (CH 2) 4 -, - (CH 2) 3 -S- (CH 2) 3 - group having the like a. Preferred is an oxygen atom in the carbon chain or at the chain end, an optionally substituted nitrogen atom, or an alkylene group having 2 to 4 carbon atoms having a sulfur atom, more preferably-( _{CH 2) 2 -O- (CH 2} ) 2 -, - (CH 2) 2 -N- (CH 2) 2 -, - (CH 2) 2 -N (CH 3) - (CH 2) 2 -, It is a group having — (CH ₂ ) ₂ —S— (CH ₂ ) ₂ —.

In the formula (1), the ring structure formed by the nitrogen atom bonded to the sulfonyl group and X ¹ and the ring structure formed by the nitrogen atom bonded to the sulfonyl group and X ² are a 5-membered ring or A 6-membered ring is preferred. If the ring structure is a 4-membered ring or less, it may be difficult to produce, and if the ring structure exceeds a 7-membered ring, the solubility in a non-aqueous solvent may be reduced.

In the formula _(1), A is shows the _{C m H (2m-n)} Z n, m is an integer from 1 to 6, n is an integer of 0 to 12, Z is substituted A good alkyl group having 1 to 4 carbon atoms, a silyl group, a phosphonic acid ester group, an acyl group, a cyano group, or a nitro group is shown. The preferable upper limit of m is 4, a more preferable upper limit is 2, and A is preferably a methylene group or an ethylene group. When Z is a substituted alkyl group, part or all of the alkyl group is preferably substituted with a fluorine atom.

Examples of the disulfonic acid amide compound represented by the formula (1) include bispyrrolidine methanedisulfonate, bispiperidine methanedisulfonate, bismorpholine methanedisulfonate, bisthiomorpholine methanedisulfonate, and 1,2-ethanedisulfonic acid. Bismorpholine, bis (1-methylpiperazine) methanedisulfonate, 1,1-ethanedisulfonic acid bismorpholine, ethane-1,1-disulfonic acid bispyrrolidine, ethane-1,1-disulfonic acid bispiperidine, propane-1, 1-disulfonic acid bispyrrolidine, propane-1,1-disulfonic acid bispiperidine, propane-1,1-disulfonic acid bismorpholine, 2-oxopropane-1,1-disulfonic acid bispyrrolidine, 2-oxopropane-1, 1-bissulfonic acid bismol Phosphorus, bispyrrolidine 2-oxo-2-phenyl-ethane-1,1-disulfonate, bismorpholine 2-oxo-2-phenyl-ethane-1,1-disulfonate, diethyl bis (morpholine-sulfonyl) methylphosphate, And trimethylsilanyl-methanedisulfonic acid bismorpholine. Among them, from the viewpoint of easy production, excellent storage stability, etc., bispyrrolidine methanedisulfonate, bispiperidine methanedisulfonate, bismorpholine methanedisulfonate, bisthiomorpholine methanedisulfonate, 1,2- Ethanedisulfonic acid bismorpholine and methanedisulfonic acid bis (1-methylpiperazine) are preferred.

Examples of the method for producing the disulfonic acid amide compound represented by the formula (1) include a cyclic secondary amine formed by X ¹ and an NH group, and an X ² and NH group. A cyclic secondary amine (X ¹ and X ² are the same as in formula (1)) and a group represented by A between two chlorosulfonyl groups (A is the same as in formula (1)). And a method of reacting with a compound having a).
For example, when producing bispyrrolidine methanedisulfonate, first, methanedisulfonyl chloride is added dropwise to pyrrolidine, and then triethylamine is added dropwise and stirred. After completion of the reaction, the organic layer is extracted and subjected to crystallization operation. A method of filtering the precipitated crystals can be used. In addition, when manufacturing this compound, reaction solvents, such as 1, 2- dimethoxyethane, can also be used as needed.

Since the disulfonic acid amide compound represented by the formula (1) 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 added to the non-aqueous electrolyte. When used in an electricity storage device such as a nonaqueous electrolyte secondary battery, 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 disulfonic acid amide compound represented by the formula (1) is stable with respect to moisture and temperature change, the additive for non-aqueous electrolyte of the present invention comprising the compound can be used for a long time at room temperature. It is possible to save. 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 nonaqueous electrolyte of the present invention in the nonaqueous electrolyte of the present invention (that is, the content of the disulfonic acid amide compound represented by the formula (1)) is not particularly limited, but the preferred lower limit is 0.005 mass% and a preferable upper limit is 10 mass%. When the content of the additive for a non-aqueous electrolyte of the present invention is less than 0.005% by mass, the SEI is stable by an electrochemical reduction reaction on the electrode surface when used in a non-aqueous electrolyte secondary battery or the like. May not be sufficiently 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. In addition, the non-aqueous electrolyte additive (that is, the disulfonic acid amide compound represented by the formula (1)) of the present invention may be used alone or in combination of two or more. In addition, as for content when using 2 or more types of this compound together, a preferable minimum is 0.005 mass%, and a preferable upper limit is 10 mass%.
Further, together with the additive for non-aqueous electrolyte, if necessary, general additives such as vinylene carbonate (VC), fluoroethylene carbonate (FEC), 1,3-propane sultone (PS) are added to the non-aqueous electrolyte. May be mixed.

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. Of these, cyclic carbonates and chain carbonates are more preferably used.

Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, and the like.
Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.
Examples of the aliphatic carboxylic acid ester include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, and methyl trimethyl acetate.
Examples of the lactone include γ-butyrolactone.
Examples of the lactam include ε-caprolactam and N-methylpyrrolidone.
Examples of the cyclic ether include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane and the like.
Examples of the chain ether include 1,2-diethoxyethane, ethoxymethoxyethane, and the like.
Examples of the sulfone include sulfolane.
Examples of the halogen derivative include 4-fluoro-1,3-dioxolan-2-one, 4-chloro-1,3-dioxolan-2-one, 4,5-difluoro-1,3-dioxolane-2- ON etc. are mentioned.
These nonaqueous solvents may be used alone or in combination of two or more.
These nonaqueous solvents are preferably used for nonaqueous electrolyte secondary batteries such as lithium ion batteries, electric double layer capacitors such as lithium ion capacitors, and the like.

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 the dissociation degree is high and the ionic conductivity of the electrolyte is increased. In addition, LiBF ₄ and LiPF ₆ are more preferable from the viewpoint that the oxidation-reduction characteristics have an effect of suppressing performance deterioration of the electricity storage device due to long-term use. 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 discharge is caused when used in an electricity storage device such as a non-aqueous electrolyte secondary battery. There is a risk of disturbing the characteristics and charging 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 a power storage device such as a water electrolyte secondary battery, there is a possibility that the discharge characteristics and the charge 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 nonaqueous electrolyte secondary battery according to the electricity storage device of 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 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 is used. it can.

In the non-aqueous electrolyte secondary battery according to the electricity storage device of 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 , Examples include lithium-containing composite oxides such as LiMn ₂ O ₄ , Li ₂ FeSiO ₄ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , and LiFePO ₄ .

In the non-aqueous electrolyte secondary battery according to 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 materials that can occlude and release 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 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, it has excellent storage stability, and when used in a power storage device such as a non-aqueous electrolyte secondary battery or an electric double layer capacitor, it forms stable SEI on the electrode surface to provide cycle characteristics and charge / discharge. It is possible to provide an additive for non-aqueous electrolyte that can improve battery characteristics such as capacity and internal resistance. Moreover, according to this invention, the nonaqueous electrolyte containing 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 nonaqueous electrolyte secondary battery concerning the electrical storage device of this invention.

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

Example 1
(Preparation of bispyrrolidine methanedisulfonate (Compound 1))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 7.3 g (0.103 mol) of pyrrolidine and 100 g of 1,2-dimethoxyethane, and 1,2-dimethoxyethane. While maintaining at 0 ° C., 10.0 g (0.047 mol) of methanedisulfonyl chloride dissolved in 10 g was added dropwise over 20 minutes. While maintaining the same temperature, 11.4 g (0.112 mol) of triethylamine dissolved in 10 g of 1,2-dimethoxyethane was added dropwise over 1 hour and stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and then 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. A part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried to give 6.0 g (0.021 mol) of bispyrrolidine methanedisulfonate. Acquired. The yield of bispyrrolidine methanedisulfonate was 45.2% based on methanedisulfonyl chloride.
The obtained bispyrrolidine methanedisulfonate can be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 1.58 ppm (dt, 8H), 2.80 ppm (t, 8H), 5.55 ppm (s, 2H)

(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 1 shown in Table 1 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. The nonaqueous electrolyte solution was prepared.

(Example 2)
In “(Preparation of non-aqueous electrolyte)”, a non-aqueous 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
(Production of methanepisulfonic acid bispiperidine (compound 2))
Piperidine (8.8 g, 0.103 mol) and 1,2-dimethoxyethane (100 g) were charged into a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel, and 1,2-dimethoxyethane was charged. While maintaining at 0 ° C., 10.0 g (0.047 mol) of methanedisulfonyl chloride dissolved in 10 g was added dropwise over 20 minutes. While maintaining the same temperature, 11.4 g (0.112 mol) of triethylamine dissolved in 10 g of 1,2-dimethoxyethane was added dropwise over 1 hour and stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and then 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. A part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried to give 4.5 g (0.014 mol) of bispiperidine methanedisulfonate. Acquired. The yield of bispiperidine methanedisulfonate was 30.8% based on methanedisulfonyl chloride.
In addition, the obtained methanedisulfonic acid bispiperidine was able to be identified from having the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 1.47 ppm (dt, 8H), 1.51 ppm (dt, 4H), 2.66 ppm (t, 8H), 5.73 ppm (s 2H)
In “(Preparation of non-aqueous electrolyte)”, non-aqueous electrolysis was carried out in the same manner as in Example 1, except that compound 2 was used instead of compound 1 so that the content ratio was 1.0% by mass. A liquid was prepared.

Example 4
(Preparation of bismorpholine methanedisulfonate (compound 3))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 9.0 g (0.103 mol) of morpholine and 100 g of 1,2-dimethoxyethane, and 1,2-dimethoxyethane was added. While maintaining at 0 ° C., 10.0 g (0.047 mol) of methanedisulfonyl chloride dissolved in 10 g was added dropwise over 20 minutes. While maintaining the same temperature, 11.4 g (0.112 mol) of triethylamine dissolved in 10 g of 1,2-dimethoxyethane was added dropwise over 1 hour and stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and then 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. A part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried to obtain 8.6 g (0.027 mol) of bismorpholine methanedisulfonate. Acquired. The yield of bismorpholine methanedisulfonate was 58.2% based on methanedisulfonyl chloride.
The obtained bismorpholine methanedisulfonate was identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 3.25 (t, 8H), 3.64 (t, 8H), 5.12 (s, 2H)
In “(Preparation of non-aqueous electrolyte)”, non-aqueous electrolysis was carried out in the same manner as in Example 1, except that compound 3 was used instead of compound 1 so that the content ratio was 1.0 mass%. A liquid was prepared.

(Example 5)
(Preparation of bisthiomorpholine methanedisulfonate (compound 4))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 10.6 g (0.103 mol) of thiomorpholine and 100 g of 1,2-dimethoxyethane, and 1,2- 10.0 g (0.047 mol) of methanedisulfonyl chloride dissolved in 10 g of dimethoxyethane was added dropwise over 20 minutes while maintaining the temperature at 0 ° C. While maintaining the same temperature, 11.4 g (0.112 mol) of triethylamine dissolved in 10 g of 1,2-dimethoxyethane was added dropwise over 1 hour and stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and then 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. A part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried to obtain 5.3 g (0.015 mol) of bisdimorpholine methanedisulfonate. ). The yield of bisthiomorpholine methanedisulfonate was 32.5% based on methanedisulfonyl chloride.
In addition, the obtained methanedisulfonic acid bisthiomorpholine was identified from having the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 3.33 (t, 8H), 3.66 (t, 8H), 5.13 (s, 2H)
In “(Preparation of non-aqueous electrolyte)”, non-aqueous electrolysis was carried out in the same manner as in Example 1, except that Compound 4 was used instead of Compound 1 so that the content ratio was 1.0 mass%. A liquid was prepared.

(Example 6)
(Preparation of bis (1-methylpiperazine) methanedisulfonate (Compound 5))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 10.3 g (0.103 mol) of 1-methylpiperazine and 100 g of 1,2-dimethoxyethane, and 1,2 -10.0 g (0.047 mol) of methanedisulfonyl chloride dissolved in 10 g of dimethoxyethane was added dropwise over 20 minutes while maintaining at 0 ° C. While maintaining the same temperature, 11.4 g (0.113 mol) of triethylamine dissolved in 10 g of 1,2-dimethoxyethane was added dropwise over 1 hour and stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and then 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. A part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried to obtain 6.7 g of bis (1-methylpiperazine) methane disulfonate ( 0.020 mol) was obtained. The yield of bis (1-methylpiperazine) methanedisulfonate was 41.9% based on methanedisulfonyl chloride.
The obtained bis (1-methylpiperazine) methanedisulfonate was identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 3.32 (s, 6H) 3.55 (t, 8H), 3.67 (t, 8H), 5.11 (s, 2H)
In “(Preparation of non-aqueous electrolyte)”, a non-aqueous electrolyte was prepared in the same manner as in Example 1, except that Compound 5 was used instead of Compound 1 so that the content was 1.0% by mass. Prepared.

(Example 7)
(Preparation of 1,2-ethanedisulfonic acid bismorpholine (compound 6))
A 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel was charged with 8.4 g (0.097 mol) of morpholine and 100 g of 1,2-dimethoxyethane, and 1,2-dimethoxyethane was added. 10.0 g (0.044 mol) of 1,2-ethanedisulfonyl chloride dissolved in 10 g was added dropwise over 20 minutes while maintaining the temperature at 0 ° C. While maintaining the same temperature, 10.7 g (0.106 mol) of triethylamine dissolved in 10 g of 1,2-dimethoxyethane was added dropwise over 1 hour and stirred overnight while maintaining the same temperature.
After completion of the reaction, the reaction solution was filtered, and then 100.0 g of toluene and 50.0 g of water were added to the filtrate for liquid separation. A part of the solvent was distilled off from the obtained organic layer under reduced pressure at 25 ° C., the precipitated crystals were filtered, and the obtained crystals were dried to obtain 7.6 g of 1,2-ethanedisulfonic acid bismorpholine (0 0.023 mol) was obtained. The yield of 1,2-ethanedisulfonic acid bismorpholine was 52.6% based on 1,2-ethanedisulfonyl chloride.
The obtained 1,2-ethanedisulfonic acid bismorpholine could be identified from the following physical properties.
¹ H-nuclear magnetic resonance spectrum (solvent: CDCl ₃ ) δ (ppm): 3.34 (t, 8H), 3.65 (t, 8H), 5.02 (s, 4H)
In “(Preparation of non-aqueous electrolyte)”, a non-aqueous electrolyte was prepared in the same manner as in Example 1 except that Compound 6 was used instead of Compound 1 so that the content was 1.0% by mass. Prepared.

(Comparative Example 1)
A non-aqueous electrolyte solution was prepared in the same manner as in Example 1 except that Compound 1 was not used in “(Preparation of non-aqueous electrolyte solution)” in Example 1.

(Comparative Example 2)
In Example 1, “(Preparation of nonaqueous electrolyte)”, except that 1,3-propane sultone (PS) was used instead of Compound 1 so that the content ratio was 1.0 mass%. A nonaqueous electrolytic solution was prepared in the same manner as in Example 1.

(Comparative Example 3)
In Example 1, “(Preparation of nonaqueous electrolyte)”, Example 1 was used except that vinylene carbonate (VC) was used instead of Compound 1 so that the content ratio was 1.0% by mass. A nonaqueous electrolytic solution was prepared in the same manner as described above.

(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)
In Example 1 “(Preparation of non-aqueous electrolyte)”, Example 1 was used except that instead of Compound 1, fluoroethylene carbonate (FEC) was used so that the content ratio was 1.0% by mass. A non-aqueous electrolyte was prepared in the same manner as in 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>
The following evaluation was performed about the compound 1-6 obtained in the Example, and the nonaqueous electrolyte solution obtained by the Example and the comparative example.

(Measurement of LUMO energy)
For compounds 1-6 obtained in the examples, semi-empirical molecular orbital calculations were performed with Gaussian 03 software to measure the LUMO (lowest unoccupied molecular orbital) energy. Table 1 shows LUMO energies of Compounds 1 to 6 obtained by orbit calculation.

From Table 1, the LUMO energy of the disulfonic acid amide compounds (compounds 1 to 6) represented by the formula (1) is about 0.15 eV to about 0.36 eV, which depends on the additive for non-aqueous electrolyte of the present invention. It can be seen that these disulfonic acid amide compounds have a LUMO energy lower than that of generally used non-aqueous electrolyte solvents (for example, cyclic carbonates and chain carbonates: LUMO energy of about 1.2 eV). Therefore, when the compounds 1 to 6 are used as an additive for a non-aqueous electrolyte in an electricity storage device such as a non-aqueous electrolyte secondary battery, the electrochemical reduction of the compounds 1 to 6 prior to the solvent of the non-aqueous electrolyte Occurs, and SEI is formed on the electrode, so that decomposition of solvent molecules in the electrolytic solution can be suppressed. As a result, it is difficult to form a solvent-decomposed coating film having high resistance on the electrode, and improvement of battery characteristics is expected.
As described above, the disulfonic acid amide compound represented by the formula (1) according to the additive for a non-aqueous electrolyte of the present invention has a sufficiently low LUMO energy, and an electricity storage device such as a non-aqueous electrolyte secondary battery. The present invention is effective as a novel additive for non-aqueous electrolyte solution that forms stable SEI on these electrodes.

(Evaluation of stability)
About the compound 1-6 obtained in Examples 1-7 and the fluoroethylene carbonate (FEC) generally used, the storage test for 90 days under the constant temperature and humidity of temperature 40 +/- 2 degreeC and humidity 75 +/- 5% Went. Decomposition of each compound was determined by ¹ H- nuclear magnetic resonance spectra ⁽¹ H-NMR), it was evaluated. The results are shown in Table 2.
◯: No ¹ H-NMR peak change before and after storage ×: ¹ H-NMR peak change before and after storage

(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 3 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 3, the cylindrical secondary battery using the non-aqueous electrolyte of the example has a higher discharge capacity maintenance rate during the cycle test than the cylindrical secondary battery using the non-aqueous electrolyte of the comparative example. I understand that. Therefore, when the non-aqueous electrolyte of the example is used for a non-aqueous electrolyte secondary battery or the like, the surface of the electrode of the non-aqueous electrolyte secondary battery or the like is compared with the case of using the non-aqueous electrolyte of the comparative example. It can be seen that SEI having high stability with respect to the charge / discharge cycle is formed.
Moreover, since the non-aqueous electrolyte of an Example has a small internal resistance ratio compared with the non-aqueous electrolyte of a comparative example, it turns out that the increase in internal resistance by the time of a cycle can be suppressed.

According to the present invention, when used in a non-aqueous electrolyte secondary battery, the battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance are formed by forming stable SEI on the electrode surface when used in a non-aqueous electrolyte secondary battery. An additive for non-aqueous electrolyte that can be improved can be provided. Moreover, according to this invention, the nonaqueous electrolyte containing this additive for nonaqueous electrolytes, and the electrical storage device using this nonaqueous electrolyte can be provided.

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 (9)

A non-aqueous electrolyte additive comprising a disulfonic acid amide compound represented by the following formula (1).

In formula (1), X ¹ and X ² are each independently an alkylene group having 1 to 6 carbon atoms, or a nitrogen atom which may have an oxygen atom or a substituent in the carbon chain or at the chain end. Or an alkylene group having 1 to 6 carbon atoms having a sulfur atom. _A represents _{C m H (2m-n)} Z n, m is an integer from 1 to 6, n is an integer of 0 to 12, Z is is optionally also be from 1 to 4 carbon atoms substituted An alkyl group, a silyl group, a phosphonic acid ester group, an acyl group, a cyano group, or a nitro group is shown. A non-aqueous electrolyte comprising the additive for non-aqueous electrolyte according to claim 1, a non-aqueous solvent, and an electrolyte. The nonaqueous electrolytic solution according to claim 2, 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 3. The non-aqueous electrolyte according to claim 2, 3 or 4, 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 5, 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 2, 3, 4, 5 or 6, a positive electrode, and a negative electrode. The electricity storage device according to claim 7, wherein the electricity storage device is a lithium ion battery. The electricity storage device according to claim 7, wherein the electricity storage device is a lithium ion capacitor.

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