JP2015191808A - Additive for nonaqueous electrolyte, nonaqueous electrolyte and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an additive for a nonaqueous electrolyte which is excellent in storage stability, and, when being used for a power storage device, forms a stable solid electrolyte interface on an electrode surface and thereby can improve battery characteristics such as cycle characteristics, charge/discharge capacity and internal resistance; a nonaqueous electrolyte containing the additive for a nonaqueous electrolyte; and a power storage device including the nonaqueous electrolyte.SOLUTION: An additive for a nonaqueous electrolyte contains a sulfur-containing diphenylene compound represented by the following formula (1). In the formula (1), Xand Xeach represent a vinyl group, an allyl group or a glycidyl group, and Y represents a sulfur atom or a -SO- group.

Description

The present invention relates to an additive for a non-aqueous electrolyte. 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, 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 have higher energy density compared to lead batteries and nickel cadmium batteries, and are expected to realize higher capacities.
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 because, over the course of a long charge / discharge cycle, the decomposition of the electrolyte solution due to the electrode reaction, the impregnation of the electrolyte into the electrode active material layer, and the decrease in lithium ion intercalation efficiency may occur. It is cited as a factor.

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 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.

Examples of the electrolyte additive for forming SEI include cyclic monosulfonate esters in Patent Documents 1 to 3, sulfur-containing aromatic compounds in Patent Document 4, disulfide compounds in Patent Document 5, and Patent Document 6 ~ 9 each disclose a disulfonic acid ester.
Patent Documents 10 to 13 disclose an electrolytic solution containing vinylene carbonate or vinyl ethylene carbonate, and Patent Documents 14 and 15 disclose an electrolytic solution containing 1,3-propane sultone or butane sultone. Has been.

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

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.

On the other hand, the compounds disclosed in Patent Documents 1 to 9 have high LUMO energy, insufficient performance as additives for non-aqueous electrolytes, and are chemically unstable even when LUMO energy is low. There was a problem such as. 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. Furthermore, for example, since a heat resistant temperature of about 60 ° C. is generally required for a lithium ion battery and about 80 ° C. for a lithium ion capacitor, the additive for non-aqueous electrolyte used in an electricity storage device is high. Improving the stability of was an important issue.

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. Further, the formed SEI does not have the strength to withstand long-term use, and the SEI is decomposed during use or the SEI cracks, so that the surface of the negative electrode is exposed and the electrolyte is decomposed. There was a problem that the 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 electrolytic solution that improves the battery characteristics of an electricity storage device such as a non-aqueous electrolyte secondary battery by forming SEI that is stable on the electrode surface and that improves cycle characteristics, charge / discharge capacity, internal resistance, etc. Development of additives for use was required.

The present invention is non-aqueous that has excellent storage stability and can improve battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance by forming stable SEI on the electrode surface when used in an electricity storage device. It aims at providing the additive for electrolyte solutions. 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 solution containing a sulfur-containing diphenylene compound represented by the following formula (1) (hereinafter also referred to as “a sulfur-containing diphenylene compound according to the present invention”).
The additive for non-aqueous electrolyte of the present invention is not limited to the one containing only the sulfur-containing diphenylene compound according to the present invention, and may contain other components as long as the object of the present invention is not impaired. Good.

In Formula (1), X ¹ and X ² represent a vinyl group, an allyl group, or a glycidyl group, and Y represents a sulfur atom or a —SO ₂ — group.
The present invention is described in detail below.

The present inventors have shown that the sulfur-containing diphenylene compound represented by the above formula (1) has three LU atoms, exhibits low LUMO energy that is susceptible to electrochemical reduction, and is chemically stable. I found out. Therefore, the present inventors include a non-aqueous electrolyte additive containing the sulfur-containing diphenylene compound in a non-aqueous electrolyte, and further uses the non-aqueous electrolyte for a power 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 reason why the sulfur-containing diphenylene compound 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, but is considered as follows. The sulfur-containing diphenylene compound according to the present invention is a highly polymerizable compound, and is considered to polymerize immediately upon being subjected to electrochemical reduction to form SEI containing a large number of polar groups containing sulfur atoms. Since the sulfur atom contained in this film has an unshared electron pair, the interaction with lithium ions is high, and SEI containing a large number of polar groups containing sulfur atoms can exhibit excellent ionic conductivity. It is considered to be a very high performance SEI. As a result of the formation of this SEI, it is considered that an increase in internal resistance can be suppressed and battery characteristics such as cycle characteristics and charge / discharge capacity can be improved.

Wherein in formula (1), ^{X 1} and ^{X 2} include a vinyl group, an allyl group, or represents a glycidyl group, Y is a sulfur atom, or, -SO ₂ - a group.
X ¹ and X ² may be the same or different, but are preferably the same group from the viewpoint of easy production.

Examples of the sulfur-containing diphenylene compound according to the present invention include bis (4-ethenylthiophenyl) sulfide, bis (4-propenylthiophenyl) sulfide, bis (4-glycidylthiophenyl) sulfide, and bis (4-ethenylthiophenyl). ) Sulfone, bis (4-propenylthiophenyl) sulfone, bis (4-glycidylthiophenyl) sulfone, and the like. Among these, bis (4-glycidylthiophenyl) sulfide and bis (4-glycidylthiophenyl) sulfone are preferable from the viewpoint of storage stability.

Examples of the method for producing the sulfur-containing diphenylene compound according to the present invention include a method of reacting a corresponding dithiol compound with a halide.
Specifically, for example, in the case of producing a compound (bis (4-ethenylthiophenyl) sulfide) in which Y in formula (1) is a sulfur atom and X ¹ and X ² are both vinyl groups, dithiol After reacting the compound with dihaloethane, a method of dehydrohalogenating in a polar solvent such as dimethyl sulfoxide, a method of reacting the dithiol compound and vinyl halide in the presence of a base, or the like can be used.

Since the sulfur-containing diphenylene compound according to the present invention exhibits low LUMO energy that is susceptible to electrochemical reduction, the additive for a non-aqueous electrolyte solution of the present invention containing the sulfur-containing diphenylene compound according to the present invention is non-aqueous electrolysis. When used in power storage devices such as non-aqueous electrolyte secondary batteries contained in the solution, stable SEI is formed on the electrode surface to improve battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance. Can do. Moreover, since the sulfur-containing diphenylene compound according to the present invention is stable against moisture and temperature changes, the additive for a non-aqueous electrolyte solution of the present invention containing the sulfur-containing diphenylene compound according to the present invention is It can be stored at room temperature. 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 minimum with preferable content of the additive for nonaqueous electrolytes of this invention in the nonaqueous electrolyte of this invention 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, stable SEI is sufficiently obtained by electrolysis 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 electroconductivity etc. of electrolyte solution cannot fully be ensured, but when it uses for electrical storage devices, such as a nonaqueous electrolyte secondary battery, it may interfere with charging / discharging characteristics. 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 additive for non-aqueous electrolytes of this invention may be used independently, and may be used in combination of 2 or more type. In addition, as for the total content when using 2 or more types of additives for non-aqueous electrolytes of this invention, a preferable minimum is 0.005 mass% and a preferable upper limit is 10 mass%.

The non-aqueous electrolyte of the present invention, if necessary, together with the additive for non-aqueous electrolyte of the present invention, such as vinylene carbonate (VC), fluoroethylene carbonate (FEC), 1,3-propane sultone (PS), etc. You may contain a general additive.

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 (EC), propylene carbonate, butylene carbonate, and the like.
Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate (DEC), 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 _{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. Among them, LiBF ₄ and / or LiBF ₄ and / or LiF ₄ and / or from the viewpoint that the degree of dissociation is high, the ionic conductivity of the electrolytic solution can be increased, and further, the oxidation-reduction properties have an effect of suppressing performance deterioration of the electricity storage device due to long-term use. or more preferably LiPF _6. These electrolytes may be used alone or in combination of two or more.
Incidentally, the LiBF _4, if the LiPF ₆ is used as the non-aqueous solvent, preferably mixed one or more respective cyclic carbonate and chain carbonate is more preferable to mix ethylene carbonate and diethyl carbonate.

The preferable lower limit of the concentration of the electrolyte in the nonaqueous electrolytic solution of the present invention is 0.1 mol / L, and the preferable 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. Sometimes. 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, the discharge characteristics and charging 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 the electricity storage device of the present invention.
In FIG. 1, a nonaqueous electrolyte secondary battery 1 according to an electricity storage device of the present invention includes a positive electrode plate 4 in which a positive electrode active material layer 3 is provided on one side of a positive electrode current collector 2, and a negative electrode current collector. A negative electrode plate 7 having a negative electrode active material layer 6 provided on one surface side of the body 5 is provided. 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 FIG. 1, a non-aqueous electrolyte secondary battery is shown as the electricity storage device, but the electricity storage device of the present invention is not limited to this, and can be applied to other electricity storage devices such as electric double layer capacitors. .

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, and stainless steel can be used.

As the positive electrode active material used for the positive electrode active material layer 3, a lithium-containing composite oxide is preferably used. For example, LiMnO ₂ , LiFeO ₂ , LiCoO ₂ , LiMn ₂ O ₄ , Li ₂ FeSiO ₄ , LiNi _1/3 Co Examples thereof include lithium-containing composite oxides such as _1/3 Mn _1/3 O ₂ and LiFePO ₄ .

Examples of the negative electrode active material used for the negative electrode active material layer 6 include a material 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.

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, it has excellent storage stability and can form stable SEI on the electrode surface to improve battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance. An additive for non-aqueous electrolyte 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)
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)
A nonaqueous electrolytic solution 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)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1, except that Compound 2 shown in Table 1 was added instead of Compound 1 so that the content ratio was 1.0% by mass.

Example 4
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that the compound 3 shown in Table 1 was added instead of the compound 1 so that the content ratio was 1.0% by mass.

(Example 5)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that the compound 4 shown in Table 1 was added instead of the compound 1 so that the content ratio was 1.0% by mass.

(Example 6)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that the compound 5 shown in Table 1 was added instead of the compound 1 so that the content ratio was 1.0% by mass.

(Example 7)
A nonaqueous electrolytic solution was prepared in the same manner as in Example 1 except that the compound 6 shown in Table 1 was added instead of the compound 1 so that the content ratio was 1.0% by mass.

(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 1 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 1 except that vinylene carbonate (VC) was added so as to have a content ratio of 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 1 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.

(Comparative Example 7)
Except that the compound (bis (4-ethenylthiophenyl) ether) in which the Y part of the formula (1) in the compound 1 is changed from a sulfur atom to an oxygen atom is added so that the content ratio is 1.0% by mass. A nonaqueous electrolytic solution was prepared in the same manner as in Example 1.

(Comparative Example 8)
Except that the compound (bis (4-propenylthiophenyl) ether) in which the Y part of the formula (1) in the compound 2 is changed from a sulfur atom to an oxygen atom is added so that the content ratio is 1.0 mass%. A non-aqueous electrolyte was prepared in the same manner as in Example 3.

(Comparative Example 9)
Except having added the compound (bis (4-glycidyl thiophenyl) ether) which changed the Y part of Formula (1) in the compound 3 from the sulfur atom to the oxygen atom so that a content rate might be 1.0 mass%. A nonaqueous electrolytic solution was prepared in the same manner as in Example 4.

<Evaluation>
(Measurement of LUMO energy)
For compounds 1-6 used 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.

(Stability)
The compounds 1 to 6 used in the examples and the fluoroethylene carbonate (FEC) used in Comparative Examples 5 and 6 were stored for 90 days in a constant temperature and humidity environment at a temperature of 40 ± 2 ° C. and a humidity of 75 ± 5%. test carried out, ¹ H- measure nuclear magnetic resonance spectra ^{(1 H-NMR),} check the peak of each compound before and after the storage, the case where there is no peak change in ^{1 H-NMR} before and after storage "○" The stability was evaluated as “Δ” when a slight peak change of ¹ H-NMR was confirmed before and after storage, and “x” when a clear peak change of ¹ H-NMR was confirmed before and after storage. . The results are shown in Table 2.

As shown in Table 2, the fluoroethylene carbonate (FEC) used in Comparative Examples 5 and 6 was considered to be partially hydrolyzed and had poor stability. On the other hand, the compounds 1 to 6 used in the examples were hardly changed and excellent in stability.

(Evaluation of discharge capacity maintenance ratio and internal resistance ratio)
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 each of the non-aqueous electrolytes obtained in the examples and comparative examples, the negative electrode sheet and the positive electrode sheet were laminated via a separator made of polyethylene to produce a cylindrical secondary battery.
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 (%) after 200 cycles and the internal resistance ratio after 200 cycles.
“Discharge capacity maintenance rate after 200 cycles (%)” is obtained by multiplying the value obtained by dividing discharge capacity (mAh) after 200 cycle test by discharge capacity (mAh) after 10 cycle test by 100. It is. The “internal resistance ratio after 200 cycles” is a relative value of the resistance after the 200 cycle test when the resistance before the cycle test is 1.

From Table 3, the cylindrical secondary battery using the non-aqueous electrolyte of each Example containing the compounds 1-6 which are the sulfur-containing diphenylene compounds according to the present invention is a cylindrical type using the non-aqueous electrolyte of the comparative example. It can be seen that the discharge capacity retention rate during the cycle test is higher than that of the secondary battery. Therefore, when the non-aqueous electrolyte of the example containing the sulfur-containing diphenylene compound according to the present invention as an additive for a non-aqueous electrolyte was used for a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte of the comparative example was used. Compared with the case, it turns out that SEI stable with respect to the charge / discharge cycle is formed on the electrode surface of the nonaqueous electrolyte secondary battery. Moreover, since the non-aqueous electrolyte of an Example has a small internal resistance ratio, 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 an electricity storage device, it has excellent storage stability and can form stable SEI on the electrode surface to improve battery characteristics such as cycle characteristics, charge / discharge capacity, and internal resistance. An additive for non-aqueous electrolyte 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 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 sulfur-containing diphenylene compound represented by the following formula (1).

In Formula (1), X ¹ and X ² represent a vinyl group, an allyl group, or a glycidyl group, and Y represents a sulfur atom or a —SO ₂ — group. A nonaqueous electrolytic solution comprising the additive for nonaqueous electrolytic solution according to claim 1, a nonaqueous 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 nonaqueous electrolytic solution according to claim 3. The nonaqueous electrolytic solution 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 at least one selected from the group consisting of LiSbF _6. The electrical storage device provided with the nonaqueous electrolyte solution of 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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