JP2014235929A - Additive for electrolyte and lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an electrolyte excellent in cycle characteristics of a battery; and an additive for an electrolyte, useful for a lithium ion secondary battery including the electrolyte.SOLUTION: An additive for an electrolyte contains, as an active ingredient, at least one of cyclic ether compounds represented by the following formula (1), formula (2) and formula (3).

Description

  The present invention relates to an electrolytic solution excellent in cycle characteristics of a battery and an additive for an electrolytic solution useful as a lithium ion secondary battery using the electrolytic solution.

  In recent years, lithium ion secondary batteries have been widely used as mobile devices such as smartphones, tablets, and notebook computers, or as electric vehicles and power sources for power storage. As the field of application expands year by year, further improvements in battery characteristics are desired.

A lithium ion secondary battery mainly includes a positive electrode and a negative electrode containing a material capable of inserting and extracting lithium, an electrolyte containing a lithium salt and a nonaqueous solvent, and a separator that partitions the positive electrode and the negative electrode.
As the positive electrode, for example, a lithium metal oxide such as LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiFePO ₄ is used.
As the electrolyte, ethylene carbonate, propylene carbonate, dimethyl carbonate, in a mixed solvent of ethyl methyl carbonate such carbonate _{compounds, LiPF 6, LiBF 4, LiN} (SO 2 CF 3) 2, LiN (SO 2 CF 2 CF 3 The solution which mixed Li electrolyte like ₂ is used as non-aqueous electrolyte solution.
On the other hand, as the negative electrode, metal lithium, metal compounds capable of occluding and releasing lithium (metal simple substance, oxide, lithium alloy, etc.) and graphite-based carbon materials are known, and in particular, lithium can be occluded and released. Coke, artificial graphite, and natural graphite are used.

Lithium ion secondary batteries are required to have high output and long life as well as safety in battery performance. There is a demand for both reducing the battery resistance under various conditions used and improving the battery life.
A deposit formed on the negative electrode surface is known as one of the factors that increase the battery resistance. In general, it is known that a reductive decomposition reaction of the solvent occurs on the negative electrode surface. If such a reductive decomposition reaction occurs continuously, deposits are generated and movement of lithium ions is hindered, resulting in battery resistance. Increases, the charge / discharge efficiency decreases, and the energy density of the battery decreases. In particular, when graphite-based material or lithium metal is used as the negative electrode, the reductive decomposition of the electrolytic solution is remarkable, and the battery performance is deteriorated due to generation of gas or deposition of decomposition products on the electrode surface.

Even in one of the positive electrodes, the solvent continuously undergoes an oxidative decomposition reaction, and gas generation and decomposition products accumulate, resulting in a problem that battery resistance increases and cycle characteristics deteriorate.
In view of this, various methods have been proposed in which the electrolytic solution contains an additive considered to act on the positive electrode for the purpose of suppressing the oxidation reaction decomposition of the solvent in the positive electrode and improving the cycle characteristics of the lithium ion secondary battery.

  For example, by adding an aromatic sulfide such as methylphenyl sulfide or diphenyl sulfide, the aromatic sulfide is oxidized on the surface of the positive electrode in preference to the electrolyte, and the oxidized product is diffused and reduced to the negative electrode. A method of suppressing the oxidative decomposition of the solvent by repeating the reaction of returning to the sulfide body and improving retention characteristics, charge / discharge cycle characteristics, and the like has been disclosed (see, for example, Patent Document 1). In addition, by adding a sulfide compound having an aryl group or a heterocyclic group as a substituent, the sulfide compound reacts preferentially with strongly oxidizing chemical species such as active oxygen generated on the positive electrode surface, and the solvent It has been disclosed to suppress a decrease in discharge capacity due to repeated charge and discharge by suppressing the oxidative decomposition of (see, for example, Patent Document 2).

JP 7-320779 A Japanese Patent Laid-Open No. 10-64591

  However, the sulfide compound as in Patent Document 1 or Patent Document 2 itself is decomposed into a radical body, and there is a problem that cycle characteristics are deteriorated by reacting with an electrolytic solution or an electrode.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by using an electrolytic solution containing a specific cyclic ether compound in a lithium ion secondary battery, and have completed the present invention.

That is, the present invention provides the following [1] to [5].
[1] An additive for electrolytic solution containing at least one cyclic ether compound represented by the following formula (1), formula (2) and formula (3) as an active ingredient.

[2] An electrolytic solution containing the additive for electrolytic solution of [1].
[3] The electrolytic solution according to [2], further comprising an amine compound.
[4] The electrolytic solution according to [2] or [3], which is for a lithium ion secondary battery or a lithium ion capacitor.
[5] A lithium ion secondary battery having the electrolyte solution according to any one of [2] to [4].

  According to the electrolytic solution containing the additive for electrolytic solution of the present invention, the cycle characteristics of the lithium ion secondary battery can be greatly improved.

  Hereinafter, the additive for electrolyte solution, the electrolyte solution containing the additive, and the lithium ion secondary battery of the present invention will be described.

  The additive for electrolytic solution of the present invention is a cyclic ether compound represented by formula (1), formula (2), and formula (3) [hereinafter, these are referred to as cyclic ether compound (A). ] As an active ingredient. The cyclic ether compound (A) has a cyclic ether bond and a double bond as an essential structure in the molecule.

  4-methyl-3,4-dihydro-2H-pyran represented by formula (1) as cyclic ether compound (A), 4-methyl-5,6-dihydro-2H- represented by formula (2) Both pyran and 4-methylenetetrahydropyran represented by formula (3) are known compounds, and the method for obtaining them is not particularly limited. They may be obtained commercially or synthesized with reference to the methods described in, for example, JP-A Nos. 51-13777, 51-133270, and 6-271559. .

  The additive for an electrolytic solution of the present invention containing a cyclic ether compound (A) as an active ingredient is particularly useful as an additive for a non-aqueous electrolytic solution of a lithium ion secondary battery, and greatly improves charge / discharge cycle characteristics. be able to. The cause of the improvement effect is not clear, but the cyclic ether compound (A) added to the electrolytic solution forms a protective film by polymerization of the double bond portion on the electrode surface in the lithium ion secondary battery during charging. It is presumed that the presence of the protective film suppresses the continuous decomposition of the solvent constituting the electrolytic solution on the electrode surface. However, the present invention is not limited by this assumption.

A cyclic ether compound (A) may be used individually by 1 type, or may use 2 or more types together.
The amount of the additive for electrolytic solution of the present invention is 0 as the amount of the cyclic ether compound (A) contained in the additive (the total content in the case of 2 or more) with respect to the total mass of the electrolytic solution. It is preferably 0.001% by mass to 10% by mass, and more preferably 0.05% by mass to 5% by mass. If it is the said range, cycling characteristics can be improved more effectively.

The cyclic ether compound (A) is stable in a situation where no acid comes into contact, but has a property of polymerizing when in contact with an acid. Therefore, for example, when LiPF ₆ is used as an electrolyte, undesired polymerization occurs due to contact with hydrofluoric acid (HF) produced by a small amount of water. Therefore, it is preferable that a base for capturing the acid coexists in the electrolytic solution in order to obtain a sufficient effect of the cyclic ether compound (A) which is an effective component of the additive for electrolytic solution of the present invention.
As such a base, an amine compound is very preferable. For example, primary amines such as ethylamine, propylamine, propylamine, butylamine, and ethylenediamine; secondary amines such as diethylamine, dipropylamine, and dibutylamine; triethylamine, tributylamine, N, N , N ′, N′-tetramethylethylenediamine, N, N-dimethylaniline, tertiary amines such as 1,8-diazabicyclo [5.4.0] undec-7-ene; pyridine, 4-dimethylaminopyridine, picoline , Heterocyclic amines such as lutidine, imidazole and pyrimidine. These amine compounds may be used alone or in combination of two or more.

When the amine compound is further coexisted with the electrolytic solution additive of the present invention, the amount can be appropriately set from the viewpoint of making the effect of the present invention sufficient, but if it is too small, for example, in the electrolytic solution containing LiPF ₆ The polymerization of the cyclic ether compound (A) by HF may not be suppressed, and if it is too much, the initial internal resistance may be increased. Therefore, the amount of the amine compound contains the cyclic ether compound (A) and the amine compound. 0.005 mass%-0.1 mass% are preferable normally with respect to the electrolyte solution of the state which does not carry out, and 0.05 mass%-0.1 mass% are more preferable.

  The electrolytic solution of the present invention may optionally contain a known component used as a lithium ion secondary battery in addition to the electrolytic solution additive of the present invention. Although the component which the electrolyte solution of this invention may contain is demonstrated below, it is not limited to these at all. The electrolytic solution generally contains an electrolyte and a nonaqueous solvent.

Examples of the nonaqueous solvent include a cyclic or chain aprotic solvent.
Examples of the cyclic aprotic solvent include cyclic carbonates, cyclic carboxylic acid esters, cyclic sulfones, and cyclic ethers. These may be used singly or in combination of two or more. Good.
Specific examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-pentylene carbonate and the like. Among these, ethylene carbonate and / or propylene carbonate are preferable from the viewpoint of the dielectric constant. In the case of a battery using graphite as the negative electrode material, ethylene carbonate is more preferable. These cyclic carbonates may be used as a mixture of two or more.
Specific examples of the cyclic carboxylic acid ester include γ-butyrolactone, δ-valerolactone, methyl γ-butyrolactone, ethyl γ-butyrolactone, methyl δ-valerolactone, and ethyl δ-valerolactone.
Specific examples of the cyclic sulfone include sulfolane, 2-methylsulfolane, and 3-methylsulfolane.
Examples of the cyclic ether include tetrahydrofuran, tetrahydropyran, 2-methyltetrahydrofuran, 1,3-dioxolane, 1,4-dioxane and the like.
Examples of the chain aprotic solvent include a chain carbonate, a chain carboxylate, a chain ether, a chain sulfone, and a chain phosphate.
Specific examples of the chain carbonate include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, methyl butyl carbonate, ethyl butyl carbonate, dibutyl carbonate and the like.
Specific examples of the chain carboxylic acid ester include methyl acetate, ethyl acetate, propyl acetate, methyl propionate, and methyl pivalate.
Specific examples of the chain ether include dimethoxymethane, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane and the like.
Specific examples of the chain sulfone include dimethyl sulfone, diethyl sulfone, dipropyl sulfone, methyl ethyl sulfone, methylpropyl sulfone and the like.
Specific examples of the chain phosphate ester include trimethyl phosphate, triethyl phosphate, ethyl dimethyl phosphate, diethyl methyl phosphate, tripropyl phosphate, tributyl phosphate, tri (trifluoromethyl) phosphate, and the like. .

  The electrolytic solution in the present invention may contain a solvent other than the above as a non-aqueous solvent. Specifically, amides such as dimethylformamide and dimethylacetamide; cyclic amides such as N-methylpyrrolidone and N-ethylpyrrolidone; boron compounds such as trimethyl borate, triethyl borate and tributyl borate; nitriles such as acetonitrile; methyl-N , N-dimethylcarbamate, a chain carbamate; N, N-dimethylimidazolidinone, a cyclic urea; a fluorine-containing ether.

  When the cyclic aprotic solvent and the chain aprotic solvent are used in the electrolytic solution of the present invention, only one cyclic aprotic solvent or two or more cyclic aprotic solvents may be used. An aprotic solvent and a chain-like protic solvent may be mixed and used. When improving the load characteristics and low temperature characteristics of the battery, it is preferable to use a mixture of a cyclic aprotic solvent and a chain aprotic solvent as the nonaqueous solvent. From the electrochemical stability of the electrolytic solution, it is preferable to use a cyclic carbonate as the cyclic aprotic solvent and a chain carbonate as the chain aprotic solvent. In addition, the conductivity of the electrolyte solution related to the charge / discharge characteristics of the battery can also be increased by a combination of the cyclic carboxylic acid ester and the cyclic carbonate and / or the chain carbonate.

From the viewpoint of forming the surface film of the negative electrode, a vinylene carbonate compound may be contained as another additive to the electrolytic solution. Specific examples of the vinylene carbonate compound include vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, propyl vinylene carbonate, dimethyl vinylene carbonate, and the like. Of these, vinylene carbonate is most preferred. These may be used alone or in combination of two or more.
When the vinylene carbonate compound is contained, the amount thereof (the total content in the case of two or more) is usually preferably 0.001% by mass to 10% by mass, and 0.05% by mass to More preferably, it is 5 mass%.

From the viewpoint of forming the surface film of the negative electrode, a halogenated cyclic carbonate may also be contained as another additive to the electrolytic solution. Specific examples of the halogenated cyclic carbonate include 4-fluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,4,5-trifluoroethylene carbonate, 4,4,5,5. -Tetrafluoroethylene carbonate etc. are mentioned. Among these, 4,5-difluoroethylene carbonate and 4-fluoroethylene carbonate are most preferable. These may be used alone or in combination of two or more.
When the halogenated cyclic carbonate is contained, the amount thereof (in the case of two or more types, the total content) is usually preferably 0.001% by mass to 10% by mass, and 0.05% by mass with respect to the total mass of the electrolytic solution. More preferably, it is -5 mass%.

From the viewpoint of forming the surface film of the negative electrode, an S═O bond-bearing compound may also be contained as another additive to the electrolytic solution. Specific examples of the compound having an S═O bond include 1,3-propane sultone, 1,4-butanediol dimethane sulfonate, divinyl sulfone, 2-propynyl methane sulfonate, pentafluoromethane sulfonate, ethylene sulfite, and vinyl ethylene sulfite. Phyto, vinylene sulfite, methyl 2-propynyl sulfite, ethyl 2-propynyl sulfite, dipropynyl sulfite, cyclohexyl sulfite, ethylene sulfate and the like can be mentioned. These may be used alone or in combination of two or more.
When the S═O bond-bearing compound is contained, the amount (the total content in the case of two or more) is usually preferably 0.001% by mass to 10% by mass with respect to the total mass of the non-aqueous electrolyte. It is more preferable that it is 0.05 mass%-5 mass%.

The electrolyte can be used without any particular limitation those generally used as an electrolyte of a lithium ion secondary battery, lithium salts of inorganic acids _{[LiPF 6,} etc. LiBF _4, LiSbF 6, LiAsF _6, and LiClO _4]; [LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) ₃ etc.]. Among these, LiPF ₆ is preferable from the viewpoint of battery output and cycle characteristics. The concentration of the electrolyte is preferably 0.01 mol / L to 3 mol / L, more preferably 0.05 mol / L to 1.5 mol / L from the viewpoint of battery output and cycle characteristics.

  There is no particular limitation on the method for preparing the electrolytic solution, and the electrolyte, the additive for electrolytic solution of the present invention, and other additives are dissolved in the non-aqueous solvent represented by the cyclic or chain aprotic solvent described above. Can be prepared. In preparing the electrolytic solution, it is preferable to dehydrate each raw material in advance so that the amount of water in the electrolytic solution is 50 ppm or less.

  The electrolytic solution of the present invention can be used for a lithium ion secondary battery or a lithium ion capacitor, but is particularly useful as an electrolytic solution for a lithium ion secondary battery. The lithium ion secondary battery will be described below. The lithium ion secondary battery of this invention contains the negative electrode, the positive electrode, and the electrolyte solution of this invention, and the separator is normally provided between the negative electrode and the positive electrode.

As a positive electrode in a lithium ion secondary battery, a positive electrode active material, a conductive agent and a binder dispersed in a solvent and slurried are applied to a positive electrode current collector with a coating device such as a bar coater and dried. Then, the solvent can be removed and, if necessary, a product pressed with a press machine can be used.
As the positive electrode active material, composite oxides of lithium and transition metals (LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O _4, etc.), transition metal oxides (MnO ₂ , V ₂ O _5, etc.), transition metal sulfides Products (such as MoS ₂ and TiS ₂ ), and conductive polymers (such as polyaniline, polyvinylidene fluoride, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene, and polycarbazole).
Conductive agents include graphite (natural graphite, artificial graphite, etc.), carbon blacks (carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc.), metal powder (aluminum powder, nickel) Powder) and conductive metal oxides (such as zinc oxide and titanium oxide).
Examples of the binder include polymer compounds such as starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, and polypropylene.
Examples of the solvent include 1-methyl-2-pyrrolidone, methyl ethyl ketone, dimethylformamide, dimethylacetamide, N, N-dimethylaminopropylamine and tetrahydrofuran.
Examples of the current collector for positive electrode include aluminum, titanium, stainless steel, nickel, baked carbon, conductive polymer, and conductive glass.

In the lithium ion secondary battery, preferred contents of the positive electrode active material, the conductive agent, and the binder based on the total weight of the positive electrode are as follows.
Content of a positive electrode active material becomes like this. Preferably it is 70-98 mass%, More preferably, it is 90-98 mass%. The content of the conductive agent is preferably 1 to 29% by mass, more preferably 1 to 10% by mass. The content of the binder is preferably 1 to 29% by mass, more preferably 1 to 10% by mass.
The amount of the solvent used in the slurry formation of the positive electrode active material, the conductive agent and the binder is preferably 20 to 70% by mass, more preferably based on the total weight of the positive electrode active material, the conductive agent and the binder. 30 to 60% by mass.

As a negative electrode in a lithium ion secondary battery, a negative electrode active material, a conductive agent and a binder dispersed in a solvent and slurried are applied to a negative electrode current collector with a coating device such as a bar coater and dried. Then, the solvent can be removed and, if necessary, a product pressed with a press machine can be used.
Negative electrode active materials include graphite, polymer compound fired bodies (for example, those obtained by firing and carbonizing phenol resin, furan resin, etc.), cokes (pitch coke, needle coke, petroleum coke, etc.), carbon fiber, high conductivity Examples include molecules (such as polyacetylene and pyripyrrole), metal alloys (such as lithium-aluminum alloys, lithium-aluminum-manganese alloys, and lithium-titanium alloys), and silicon. As the conductive agent, the binder and the solvent, the same materials as those used for the production of the positive electrode can be used. Examples of the current collector for the negative electrode include copper, stainless steel, nickel, aluminum, titanium, calcined carbon, conductive polymer, conductive glass, and aluminum-cadmium alloy.

In the lithium ion secondary battery, the preferable contents of the negative electrode active material, the conductive agent, and the binder based on the total weight of the negative electrode are respectively preferable for the positive electrode active material, the conductive agent, and the binder based on the total weight of the positive electrode. It is the same as the content.
The amount of the solvent used in slurrying the negative electrode active material, the conductive agent and the binder is the same as the amount of solvent used in slurrying the positive electrode active material, the conductive agent and the binder.

  As separators in lithium ion secondary batteries, polyethylene, polypropylene microporous film, porous polyethylene film and multilayer film of polypropylene, polyester fiber, aramid fiber, non-woven fabric made of glass fiber, etc. The thing to which ceramic fine particles, such as a silica, an alumina, and a titania, were made to adhere is mentioned.

  The shape of the lithium ion secondary battery in the present invention is not particularly limited, and can be applied to various shapes such as a square shape, an oval shape, a coin shape, a button shape, and a sheet shape battery.

  The use of the electrolytic solution of the present invention and the lithium ion secondary battery using the electrolytic solution is not particularly limited, and can be used for various known uses.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these. The abbreviations used are shown below.
Cyclic ether compound (A)
A-1: 4-methyl-3,4-dihydro-2H-pyran A-2: 4-methyl-5,6-dihydro-2H-pyran A-3: 4-methylenetetrahydropyran
Non-aqueous solvent EC: ethylene carbonate EMC: ethyl methyl carbonate
Amine compound Bu ₃ N: Tributylamine DBU: 1,8-diazabicyclo [5.4.0] undec-7-ene Py: pyridine
Other additives VC: Vinylene carbonate

Examples 1-8
<Preparation of electrolyte>
EC and EMC were mixed at a ratio of 1: 3 (volume ratio), and LiPF ₆ was dissolved as an electrolyte at 25 ° C. so that the electrolyte concentration in the finally obtained electrolyte was 1 mol / L, and then cyclic. The ether compound (A) and the amine compound were sequentially added so as to have the concentrations shown in Table 1 to prepare each electrolyte solution (B1 to B8). The water content of each electrolytic solution was less than 10 ppm.

<Residual ratio of cyclic ether compound (A) [effect of addition of amine compound]>
The residual amount of the cyclic ether compound (A) in a state where each electrolytic solution was heated to 45 ° C. was measured by gas chromatography, and the color was simultaneously observed. The residual ratio of the cyclic ether compound (A) was calculated as a relative value when the amount of the added cyclic ether compound (A) was 100%. The results are shown in Table 2.

  From Table 2, in the electrolyte solution of the present invention, the case where the amine compound was allowed to coexist (Examples 1 to 5) than the case where the amine compound was not allowed to coexist (Examples 6 to 8). The cyclic ether compound (A), which is an active ingredient of the agent, is excellent in stability during heating. That is, the additive for electrolyte of the present invention can be suitably used for a lithium ion secondary battery by coexisting with an amine compound to form an electrolytic solution.

Examples 9 to 16 and Comparative Example 1
<Preparation of electrolyte>
EC and EMC were mixed at a ratio of 1: 3 (volume ratio), and LiPF ₆ as an electrolyte was dissolved at 25 ° C. so that the electrolyte concentration in the finally obtained electrolyte was 1 mol / L, and then cyclic ether Each electrolyte solution (B9 to B17) was prepared by sequentially adding compound (A), an amine compound, and VC as other additives so as to have concentrations shown in Table 3. The water content of each electrolytic solution was less than 10 ppm.

<Creation of lithium ion secondary battery>
Using each electrolytic solution, a lithium ion secondary battery was created with the following configuration and procedure.
(Creation of positive electrode)
A paste slurry is prepared by kneading 5 parts by weight of polyvinylidene fluoride as a binder, 5 parts by weight of acetylene black as a conductive agent, 90 parts by weight of LiCoO ₂ as a positive electrode active material, and N-methylpyrrolidone as a solvent. did. Next, the slurry was applied to an aluminum foil current collector having a thickness of 20 μm, dried, and then compressed by a roll press to obtain a sheet-like positive electrode.
(Creation of negative electrode)
A paste-like slurry was prepared by adding 95 parts by mass of graphite (graphite), 2 parts by mass of carboxymethylcellulose, 3 parts by mass of styrene butadiene rubber, and water. Next, the slurry was applied to a copper foil current collector having a thickness of 14 μm and dried, and then compressed by a roll press to obtain a sheet-like negative electrode.
(Creation of test battery)
The above positive electrode was 13 mm in diameter and the negative electrode was 14 mm in diameter, and each was punched into a circular shape to obtain disk-shaped electrodes (positive electrode and negative electrode). Further, a microporous polyethylene film having a thickness of 20 μm was punched into a disk shape having a diameter of 17 mm to obtain a separator. The obtained disc-shaped positive electrode, separator, and negative electrode are laminated in this order in a stainless steel battery can (2032 size), and 20 μL of each electrolyte (B9 to B17) is injected to be contained in the separator, positive electrode, and negative electrode. Soaked. Further, an aluminum plate (thickness 1.2 mm, diameter 16 mm) and a spring are placed on the positive electrode, and the battery is sealed by caulking the battery can lid through a polypropylene gasket, and the diameter is 20 mm and height. A 3.2 mm coin-type lithium ion secondary battery (hereinafter sometimes referred to as “test battery”) was produced.

<Cycle characteristic test (battery performance evaluation)>
Each completed test battery was subjected to a high-temperature cycle test. The high-temperature cycle test consists of a constant current and constant voltage charge at 60 ° C. with a charge current of 600 mA, a charge voltage of 4.20 V and a charge time of 2.5 hours, and a constant current discharge with a discharge current of 600 mA and a final voltage of 2.80 V. Charging / discharging was repeated 50 cycles. At this time, the battery capacity at the first charge and the discharge capacity at the 50th cycle were measured, and the cycle characteristics were calculated from the following formula. The results are shown in Table 4. The larger the value, the better the charge / discharge cycle characteristics.
Moreover, the internal resistance (AC resistance) of the battery was measured using a 1 kHz impedance meter after the 50th cycle discharge. The relative values with the internal resistance value of Comparative Example 1 as 100 are also shown in Table 4.

Cycle characteristics (%) =
(Battery capacity at the 50th cycle charge (mAh) / Battery capacity at the first charge (mAh)) x 100

  From Table 4, when the lithium ion secondary battery was produced using the electrolyte solution containing the electrolyte solution additive of the present invention (Examples 9 to 16), the cycle characteristics were not contained (Comparative Example 1). It turns out that it is favorable compared. Comparing the case where the amine compound coexists (Examples 9 to 13) and the case where the amine compound does not coexist (Examples 14 to 16), the cycle characteristics are more excellent in the case of coexistence.

  Since the electrolytic solution containing the additive for electrolytic solution containing the cyclic ether compound (A) as an active ingredient of the present invention is excellent in cycle characteristics when a lithium ion secondary battery is produced, the lithium ion secondary It is useful as a battery electrolyte.

Claims (5)

The additive for electrolyte solutions which contains at least 1 sort (s) of the cyclic ether compound represented by following formula (1), Formula (2), and Formula (3) as an active ingredient.

The electrolyte solution containing the additive for electrolyte solutions of Claim 1. Furthermore, the electrolyte solution of Claim 2 formed by coexisting an amine compound. The electrolyte solution according to claim 2 or 3, which is used for a lithium ion secondary battery or a lithium ion capacitor. The lithium ion secondary battery which has the electrolyte solution in any one of Claims 2-4.