JP3449710B2 - Organic electrolytes Organic electrolytes for secondary batteries - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electrolyte solution for an organic electrolyte solution secondary battery, and more particularly to an organic electrolyte solution which can form an organic electrolyte solution secondary battery having excellent safety.

[0002]

2. Description of the Related Art An organic electrolytic solution secondary battery is a secondary battery using an organic solvent as a solvent for the electrolytic solution. The organic electrolytic solution secondary battery has a large capacity, high voltage, high energy density and high capacity. Since it is an output, the demand tends to increase more and more.

As a solvent for the organic electrolytic solution of this battery (in this document, this "solvent for the organic electrolytic solution" is abbreviated as "electrolytic solution solvent"), a cyclic solvent such as ethylene carbonate has hitherto been used. Ester and chain ester such as dimethyl carbonate, diethyl carbonate and methyl propionate have been mixed and used.

[0004] However, while studying this organic electrolyte secondary battery with the aim of further improving safety,
If a chain ester is used as the main solvent of the organic electrolyte, or if the negative electrode has a large chargeable / dischargeable capacity, unless the battery structure is adequately devised, the battery may be short-circuited internally or nailed. It was found that there is a tendency for the safety to be lowered when given.

Usually, a protective circuit is used to prevent overcharging and prevent an internal short circuit. In a normal internal short circuit, the battery heats up and no abnormal situation occurs. Moreover, nail stabs are rare and rare unless they are intentionally performed by the user. It is possible that the battery may be partially crushed due to a shock accident or the like.

For this reason, a battery crush test is conducted, but it is usually safe. However, it cannot be said that it is safe enough to test dozens of them, and it is desirable to confirm the safety by conducting a test under a more dangerous condition.

On the other hand, in the nail piercing test, the battery is surely short-circuited in a smaller portion compared to the battery crushing test, so that the current is concentrated in the short-circuited portion and heat is generated more easily, and the battery is partially rapidly heated to a high temperature. It is easy to become. Therefore, in a battery having a spirally wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are spirally wound through a separator that generates a fuse due to heat generation of the battery, the fuse of the separator (clogging due to melting)
Is more likely to occur, and the amount of heat generated by the reaction between the electrolytic solution and the negative electrode at the short-circuited portion is increased. Therefore, the amount of heat generated by the battery is further increased. Therefore, the nail penetration test is effective as a severe test for confirming safety. Furthermore, when the nail penetration test is performed at a high temperature of 40 ° C. rather than at room temperature, the temperature of the battery rises to a higher temperature and the thermal runaway reaction of the battery is more likely to occur. Further, when the nail is stopped in the middle of the battery as in the case of ½ nail sticking, the short-circuited portion is reduced and the current is more concentrated and heat is easily generated. Therefore, in order to obtain higher safety, it is desirable that it can withstand the ½ nail penetration test under such heating to some extent.

[0008]

By the way, when a compound capable of deintercalating lithium such as carbon is used in the negative electrode, the reactivity with the electrolytic solution at a high temperature is much lower than that in the case of using metallic lithium. The safety of is improved. In order to improve the safety, the presence of a good-quality film formed by reacting with the electrolytic solution on the surface of the negative electrode using a compound capable of deintercalating lithium is essential.

Regarding the reaction with the electrolytic solution on the surface of the negative electrode, see D. Aurbach et al. Have reported that organic carbonate (ROCO ₂ Li), Li ₂ CO ₃ , alkoxide (ROLi), etc. are formed on carbon [J. Electrochemical Soc. , V
ol142 (No. 9), p2882 (1995)].
Further, in the same report, in a mixed solvent of cyclic ester ethylene carbonate and chain ester diethyl carbonate, the ratio of chain ester diethyl carbonate to cyclic ester ethylene carbonate was 1: 1.
Higher amounts are reported to adversely affect cycle performance. Further, also in the study by the present inventors, especially when the proportion of chain ester such as diethyl carbonate is large, especially when the proportion of chain ester having a methyl group is large, the safety in short circuit and nail sticking is lowered. It turns out that there is a tendency.

Therefore, the present invention solves the problems relating to the safety of conventional organic electrolyte solutions for organic electrolyte secondary batteries,
An object of the present invention is to provide an organic electrolyte solution that can form an organic electrolyte secondary battery with excellent safety.

[0011]

According to the present invention, a chain ester is used as a main solvent in an amount of more than 50% by volume in a whole electrolyte solution solvent, and a chain ester having at least a methyl group is used as an electrolyte solution solvent. In an organic electrolyte solution for an organic electrolyte solution secondary battery, a nonionic aromatic compound having an alkyl group having 4 or more carbon atoms is contained, and 10% by volume or more of ethylene carbonate is contained in all the electrolyte solution solvents. By doing so, when used in an organic electrolyte secondary battery, a film is formed on the surface of the negative electrode to solve the above-mentioned problems.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The number of carbon atoms used in the present invention is 4
Examples of the nonionic aromatic compound having at least one alkyl group include trimellitic acid ester and tri-2
-Ethylhexyl trimellitate [C ₆ H ₃ (COOC
Derivatives of trimellitic acid esters, such as ₈ H ₁₇ ) ₃ ],
Dibutyl phthalate [C ₆ H ₄ (COOC
₄ H _{9) 2],} butylbenzene _{(C 6 H 5 -C 4 H} 9,
Normal or tertiary or iso), cyclohexylbenzene _{(C 6 H 11 -C 6 H} 5) , and the like.

The alkyl group of the nonionic aromatic compound must have 4 or more carbon atoms, and preferably has 5 or more carbon atoms. The alkyl group may be directly bonded to the benzene ring, but is more preferably bonded to the benzene ring via a COO group. That is, the longer the alkyl group is and the more the COO group is, the larger the barrier effect on the negative electrode surface (the effect of suppressing the rapid reaction between the electrode and the electrolytic solution at high temperature) is. Here, the nonionic property of the nonionic aromatic compound means that the molecule does not have a cation part or an anion part.

In the present invention, the content of the nonionic aromatic compound having an alkyl group having 4 or more carbon atoms in the organic electrolytic solution is 0.1 part by volume with respect to 100 parts by volume of the electrolytic solution solvent. It is desirable that the amount is not less than 0.2 part by volume, more desirably not less than 0.2 part by volume, most desirably not less than 0.5 part by volume. When the nonionic aromatic compound having an alkyl group having 4 or more carbon atoms is solid, a value converted into volume by its density is used. Further, the content of the nonionic aromatic compound having an alkyl group having 4 or more carbon atoms in the organic electrolytic solution is 100% by weight of the electrolytic solution solvent.
The capacity is preferably 10 or less, more preferably 2 or less, and most preferably 1 or less.

If the content of the above-mentioned nonionic aromatic compound having an alkyl group having 4 or more carbon atoms in the organic electrolyte is less than the above, safety may not be sufficiently improved. If the content of the nonionic aromatic compound having an alkyl group having 4 or more carbon atoms in the organic electrolytic solution is larger than the above, the cycle characteristics and load characteristics of the battery may be deteriorated.

The present inventors have examined in detail the effect of the addition of the aromatic compound to the organic electrolytic solution on the safety of the battery. Explaining this in detail, the present inventors first conducted a nail penetration test of a lithium-ion battery assuming an internal short circuit, etc., and although the risk is low with a normal commercially available lithium-ion battery, the energy of the battery is low. It was found that the danger increases as the density increases.

A compound such as a carbon material capable of deintercalating lithium is usually used for the negative electrode of these batteries.
About 1 if the negative electrode is overcharged and some lithium is electrodeposited
An exothermic reaction occurs between the electrolytic solution and the electrodeposited lithium or the carbon material in which lithium is inserted from around 00 ° C. On the other hand, the desorption of lithium in the positive electrode lowers the reaction initiation temperature with the electrolytic solution, and when the temperature rises to the thermal runaway temperature of the positive electrode due to the reaction heat of the negative electrode, the battery will abnormally generate heat.

Because of the exothermic phenomenon associated with such a continuous reaction, the larger the dischargeable capacity per unit volume of the negative electrode, the greater the amount of heat generated per unit volume of the battery when heat is generated during overcharge, and the battery temperature Is likely to rise to the thermal runaway temperature of the positive electrode. Therefore, it is necessary to suppress the exothermic reaction between the negative electrode and the electrolytic solution as the battery has a larger negative electrode capacity per unit volume. In addition, since the amount of heat generated increases even when the battery size is large, it is necessary to suppress the exothermic reaction between the negative electrode and the electrolytic solution, and the nonionic aromatic compound having an alkyl group of 4 or more carbon atoms of the present invention The effect of including is remarkably exhibited. Single cell size is 10 cm
^{When it is 3} or more, especially 15 cm ³ or more, the calorific value increases, so that the effect of the present invention is more significantly exhibited.

In the present invention, the reason why the safety can be improved by using the organic electrolytic solution containing the nonionic aromatic compound having an alkyl group having 4 or more carbon atoms is considered as follows.

By preparing the negative electrode with a compound capable of deintercalating lithium such as a carbon material, the reactivity of the electrolytic solution and the negative electrode at high temperature is suppressed more than in the case where metallic lithium is used for the negative electrode. The increase in the chargeable / dischargeable capacity of the negative electrode increases the reactivity with the electrolytic solution, and the amount of heat generated when the battery heats up and the reaction between the negative electrode and the electrolytic solution increases, making it easy for the temperature to rise. . However, when a nonionic aromatic compound having 4 or more carbon atoms is added to the organic electrolytic solution, the aromatic compound is adsorbed on the surface of the negative electrode and the direct contact between the surface of the negative electrode and the chain ester occurs. Since the contact is suppressed, it is considered that the reactivity between the negative electrode and the electrolytic solution is reduced and the temperature rise is limited. It was also found that the aromatic compound having an alkyl group having 4 or more carbon atoms was more effective. The details will be clarified in Examples described later.

The chain ester used as the main solvent in the electrolytic solution solvent is, for example, an organic solvent having a chain COO-bond such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and methyl propionate. The main solvent means that the chain ester exceeds 50% by volume in the total electrolyte solvent containing these chain esters. If the chain ester content exceeds 65% by volume, the battery safety in the nail penetration test tends to decrease,
The effect of adding the nonionic aromatic compound having an alkyl group having 4 or more carbon atoms is increased. When the chain ester exceeds 70% by volume, the effect of adding the nonionic aromatic compound having the above alkyl group is further increased,
When the chain ester content exceeds 75% by volume, the effect of adding the nonionic aromatic compound having an alkyl group is further enhanced. Also, when the chain ester has a methyl group, the safety of the battery is likely to be lowered, so that the effect of adding the nonionic aromatic compound having an alkyl group becomes more remarkable.

When the above chain ester is mixed with the following ester having a high dielectric constant (dielectric constant of 30 or more),
Since the cycle characteristics and the load characteristics of the battery are improved and the safety is improved as compared with the case where only the chain ester is used, the battery is more desirable. The above-described improvement in safety becomes remarkable when the ester having a high dielectric constant is 10% by volume or more in the entire electrolytic solution solvent (total solvent of the organic electrolytic solution). Examples of such an ester having a high dielectric constant include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (B
C), gamma-butyrolactone (γ-BL), ethylene glycol sulfite (EGS), and the like are preferable, and those having a cyclic structure are particularly preferable, cyclic carbonate is particularly preferable, and ethylene carbonate (EC) is most preferable. Therefore, in the present invention, the carbon number is 4
With a nonionic aromatic compound having at least one alkyl group, ethylene carbonate is added in an amount of 10% in all electrolyte solvent.
It is contained by volume% or more.

The ester having a high dielectric constant is preferably less than 40% by volume, more preferably 30% by volume or less, and further preferably 25% by volume or less in the total electrolyte solvent.

Examples of the solvent that can be used in combination with the chain ester other than the above-mentioned ester having a high dielectric constant include 1,2-dimethoxyethane (DME) and 1,3-dioxolane (D).
O), tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (2Me-THF), diethyl ether (DEE) and the like. In addition, an amine imide-based organic solvent, a sulfur-containing or fluorine-containing organic solvent, or the like can be used.

As the electrolyte of the organic electrolytic solution, for example,
LiClO ₄ , LiPF ₆ , LiBF ₄ , LiAs
F ₆ , LiSbF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉
SO ₃ , LiCF ₃ CO ₂ , Li ₂ C ₂ F ₄ (SO ₃ )
₂ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ S
O ₂ ) ₃ , LiC _n F _{2n + 1} SO ₃ (n ≧ 2), LiN
(Rf ₃ OSO ₂ ) ₂ [where Rf is a fluoroalkyl group] or the like may be used alone or as a mixture of two or more, and particularly LiPF ₆ and LiC ₄ F ₉ SO ₃ have good charge and discharge characteristics. From desirable. The concentration of the electrolyte in the organic electrolytic solution is not particularly limited, but it is desirable that the concentration be 1 mol / l or more because safety is improved, and 1.2 mol / l or more is more desirable. Also,
The concentration of the electrolyte in the organic electrolytic solution is 1.7 mol / l
It is desirable that it is less than the following, because good electrical characteristics are maintained,
It is more desirable that the amount is 1.5 mol / l or less.

In constructing an organic electrolytic solution secondary battery using the organic electrolytic solution of the present invention, the positive electrode active material is, for example, lithium cobalt oxide such as LiCoO ₂ .
LiMn ₂ O ₄ and other lithium manganese oxides, LiN
Lithium nickel oxide such as iO ₂ , metal oxide such as manganese dioxide, vanadium pentoxide and chromium oxide, or metal sulfide such as titanium disulfide and molybdenum disulfide is used.

For the positive electrode, for example, a mixture of the positive electrode active material and a binder such as a conductive auxiliary agent or polyvinylidene fluoride is added to the positive electrode, and the current collector material such as an aluminum foil is used as a core material. A finished product is used.

In particular, LiNiO ₂ , LiCoO ₂ , LiM
When a lithium composite oxide having an open circuit voltage at the time of charging of 4 V or more based on Li such as n ₂ O ₄ is used as the positive electrode active material, high energy density can be obtained, which is desirable. Particularly, charged LiCoO ₂ and LiNiO ₂ have a lower reaction initiation temperature with the electrolyte solvent than LiMn ₂ O ₄ and easily reach the thermal runaway temperature of the positive electrode due to heat generation of the negative electrode, so that the effect of the present invention is more significantly exerted. It

In forming an organic electrolyte secondary battery using the organic electrolyte of the present invention, the material used for the negative electrode may be any material that can dope and de-dope lithium ions, such as graphite, Pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds,
It is possible to use carbon materials such as mesocarbon microbeads, carbon fibers and activated carbon, or oxides such as Si, Sn and In.

When a carbon material is used for the negative electrode, the carbon material preferably has the following characteristics. That is, the interlayer distance d ₀₀₂ of the (002) plane is 0.35n
The thickness is preferably m or less, more preferably 0.345 nm or less, and further preferably 0.34 nm or less. Also,
The crystallite size Lc in the c-axis direction is preferably 3 nm or more, more preferably 8 nm or more, and further preferably 25 nm.
nm or more. And the average particle size is 8 to 15 μm.
m, especially 10 to 13 μm is desirable, and the purity is 99.9%
The above is desirable.

[0031]

EXAMPLES Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to only those examples.

Example 1 Methyl ethyl carbonate and ethylene carbonate were mixed at a volume ratio of 76:24, and tri-2-ethylhexyl trimellitate [C was mixed with 100 parts by volume of this mixed solvent.
₆ H ₃ (COOC ₈ H ₁₇ ) ₃ ] was added and mixed in an amount of 1 part by volume, and LiPF ₆ was dissolved in 1.4 mol / l to prepare an organic electrolytic solution.

Separately, LiC as a positive electrode active material is used.
Phosphorous graphite as a conductive additive in oO ₂ in a mass ratio of 100: 7
And mixed with each other, and this mixture was mixed with a solution of polyvinylidene fluoride dissolved in N-methylpyrrolidone to form a slurry. The positive electrode mixture slurry was passed through a 70-mesh net to remove large ones, and then a thickness of 20
A positive electrode current collector made of an aluminum foil having a thickness of μm was evenly applied on both sides and dried, then compression molded by a roller press machine, cut, and then a lead body was welded to produce a strip-shaped positive electrode.

Next, a graphite-based carbon material (provided that the interlayer distance d ₀₀₂ = 0.337 nm and the crystallite size L in the c-axis direction) was used.
90 parts by mass of a graphite-based carbon material having the characteristics of c = 95 nm, average particle size of 10 μm, and purity of 99.9%) is mixed with a solution prepared by dissolving 10 parts by mass of vinylidene fluoride in N-methylpyrrolidone to form a slurry. did. This negative electrode mixture slurry was passed through a 70-mesh net to remove large ones, and then uniformly coated on both sides of a negative electrode current collector made of a strip-shaped copper foil having a thickness of 10 μm and dried, and then a roller was used. After compression molding with a press and cutting, a lead body was welded to produce a strip-shaped negative electrode.

The band-shaped positive electrode was superposed on the band-shaped negative electrode via a microporous polyethylene film having a thickness of 25 μm and wound in a spiral shape to form a spiral electrode body, and then a cylindrical battery case having a bottom with an outer diameter of 18 mm. Then, the lead bodies of the positive electrode and the negative electrode were welded. Here, the charge and discharge capacity of the negative electrode is the normal charge condition of this battery (the operation of charging at a constant current of 1400 mA and, after reaching 4.1 V, charging at a constant voltage of 4.1 V for 2 hours 30 minutes). Then, it was 85 mAh / cm ³ .

Next, the above-mentioned organic electrolytic solution is injected into the battery case, and after the organic electrolytic solution has sufficiently penetrated into the separator or the like, the organic electrolytic solution is sealed, precharged and aged, and the tubular structure having the structure shown in FIG. 1 is formed. An organic electrolyte secondary battery was produced.

The battery shown in FIG. 1 will be briefly described. 1 is the positive electrode and 2 is the negative electrode. However, in FIG. 1, in order to avoid complication, the current collector and the like used in the production of the positive electrode 1 and the negative electrode 2 are not shown, and the positive electrode 1 and the negative electrode 2 are spirally formed with the separator 3 interposed therebetween. The spirally wound electrode body is housed in a battery case 4 made of stainless steel together with an organic electrolytic solution.

As described above, the organic electrolyte solution contains tri-2.
-Ethylhexyl trimellitate is contained, the battery case 4 also serves as a negative electrode terminal, the insulator 5 is arranged on the bottom thereof, and the insulator 6 is also arranged on the spiral electrode body. Then, a sealing body 8 is arranged in the opening of the battery case 4 via an annular insulating packing 7, and the inside of the battery is sealed by tightening the opening end of the battery case 4 inward. However, the sealing body 8 incorporates a reversible vent mechanism for preventing the gas generated inside the battery from exploding to the outside of the battery when it rises to a certain constant pressure and preventing the battery from bursting under high pressure. Has been.

Example 2 An organic electrolytic solution was prepared in the same manner as in Example 1 except that dibutyl phthalate [C ₆ H ₄ (COOC ₄ H ₉ ) ₂ ] was used instead of tri-2-ethylhexyl trimellitate. A cylindrical organic electrolyte secondary battery was produced in the same manner as in Example 1 except that the organic electrolyte was used.

Comparative Example 1 An organic electrolyte solution was prepared in the same manner as in Example 1 except that dimethyl phthalate [C ₆ H ₄ (COOCH ₃ ) ₂ ] was used instead of tri-2-ethylhexyl trimellitate. A cylindrical organic electrolyte secondary battery was produced in the same manner as in Example 1 except that the electrolytic solution was used.

Comparative Example 2 An organic electrolytic solution was prepared in the same manner as in Example 1 except that toluene was used instead of tri-2-ethylhexyl trimellitate, and the same as in Example 1 except that the organic electrolytic solution was used. A cylindrical organic electrolyte secondary battery was manufactured.

Comparative Example 3 An organic electrolytic solution was prepared in the same manner as in Example 1 except that the organic electrolytic solution did not contain tri-2-ethylhexyl trimellitate, and Example 1 was used except that the organic electrolytic solution was used. A cylindrical organic electrolyte secondary battery was prepared in the same manner as in.

Comparative Example 4 An organic electrolytic solution was prepared in the same manner as Comparative Example 3 except that the volume ratio of ethylene carbonate to methyl ethyl carbonate was 1: 1. A cylindrical organic electrolyte secondary battery was produced in the same manner as in 1.

The batteries of Examples 1 and 2 and Comparative Examples 1 to 4 were discharged at 1400 mA to 2.75 V and then discharged to 140 V.
After charging with a constant current of 0 mA and reaching 4.18 V, 4.
Charging was performed for 2 hours and 30 minutes under the condition of keeping a constant voltage of 18V. After that, the battery was placed in a constant temperature bath at 40 ° C., taken out after 2 hours, placed on a battery holder with a wooden groove, and a stainless steel nail with a shaft diameter of 3 mm was placed perpendicular to the center of the side surface of the battery. Immediately, the battery was pierced to a depth of 1/2 of the outer diameter of the battery and examined for abnormal heat generation. The results are shown in Table 1.

In this test, Examples 1-2 and Comparative Examples 1-4
For each battery, 20 batteries are used, and in Table 1, the number of batteries used in the test is shown in the denominator, and the number of batteries with abnormal heat generation is shown in the numerator to show the ratio of abnormal heat generation. 1 at 40 ℃ above
The / 2 nail penetration test is a test for confirming safety under extremely severe conditions.

[0046]

[Table 1]

As shown in Table 1, the batteries of Examples 1 and 2 using the organic electrolytic solution of the present invention generated abnormal heat even though the chain ester in the organic electrolytic solution exceeded 50% by volume. And the organic electrolyte contains a nonionic aromatic compound having an alkyl group having 4 or more carbon atoms,
Moreover, it can be seen that the safety in the nail penetration test is improved by including 10% by volume or more of ethylene carbonate in the solvent for all electrolytes. In particular, as in Example 1, when the alkyl group of the nonionic aromatic compound has 5 or more carbon atoms, the effect is further enhanced. However, as in the batteries of Comparative Examples 1 and 2, the effect is small when the number of carbon atoms of the alkyl group of the nonionic aromatic compound contained in the organic electrolytic solution is small. Among them, the one in which the alkyl group is bonded to the benzene ring through the COO group as in Comparative Example 1 is more effective than the one in which the alkyl group is directly bonded to the benzene ring as in Comparative Example 2. . Further, as in Comparative Example 4, when the amount of chain ester such as methyl ethyl carbonate is small or when the chain ester has only an ethyl group, the safety is good, and the non-chain having a carbon number of 4 or more is The effect of adding the ionic aromatic compound tends to decrease.

[0048]

As described above, in the present invention, the chain ester is used as the main solvent in an amount of more than 50% by volume in the whole electrolyte solution solvent, and the chain ester having at least a methyl group is used as the electrolyte solution solvent. In the organic electrolytic solution used as above, a nonionic aromatic compound having an alkyl group having 4 or more carbon atoms is contained in the organic electrolytic solution, and ethylene carbonate is contained in an amount of 10% by volume or more in all electrolytic solution solvents. By doing so, the safety of the battery using such an organic electrolyte can be improved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view schematically showing an example of an organic electrolytic solution secondary battery using the organic electrolytic solution of the present invention.

[Explanation of symbols]

1 positive electrode 2 Negative electrode 3 separator

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-275632 (JP, A) JP-A-5-36439 (JP, A) JP-A-10-74537 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01M 10/40 CA (STN)

Claims (10)

(57) [Claims] 1. A chain ester is used as a main solvent in an amount of more than 50% by volume in all the electrolytic solution solvents, and a chain ester having at least a methyl group is used as the electrolytic solution solvent.
Organic electrolyte solution An organic electrolyte solution for a secondary battery , wherein the above-mentioned organic electrolyte solution contains a nonionic aromatic compound having an alkyl group having 4 or more carbon atoms, and ethylene is contained in the entire electrolyte solution solvent. Rukoto is contained carbonate least 10 vol%
When used in an organic electrolyte secondary battery,
Organic electrolyte secondary battery characterized by forming a film on the surface
Organic electrolyte for ponds . Wherein the alkyl group of 4 or more carbon atoms of a non-ionic aromatic compound, 請 <br/> Motomeko 1 for organic electrolyte secondary battery according to a benzene ring that has engaged straight knotting organic electrolyte solution. 3. A non-ionic aromatic compound, an organic electrolytic solution for an organic electrolyte secondary battery according to claim 2, wherein a butylbenzene or cyclohexylbenzene. Wherein the alkyl group organic electrolytic solution for an organic electrolyte secondary battery according to claim 2 Symbol placement carbon number of 5 or more. 5. The nonionic aromatic compound has 4 carbon atoms.
The above alkyl groups are bonded to the benzene ring via the COO group.
The organic electrolyte for a secondary battery according to claim 1,
Electrolyte. 6. The nonionic aromatic compound is a trimellitic compound.
Tomic acid ester, trimellitic acid ester derivative or
The organic electrolyte solution according to claim 5, which is dibutyl phthalate.
Organic electrolyte for secondary batteries. 7. A contract in which an alkyl group has 5 or more carbon atoms.
The organic electrolyte solution for an organic electrolyte secondary battery according to claim 5. 8. A chain ester of 50 units in all electrolyte solvents
Used in a range of more than product% and up to 76% by volume.
Organic for electrolyte secondary battery according to any one of 1 to 7
Electrolyte. 9. The organic according to any one of 請 Motomeko 1-8 chain ester in all electrolyte solvents that have exceeded 65 vol%
Electrolyte solution Organic electrolyte solution for secondary batteries . 10. The content of the nonionic aromatic compound having an alkyl group having 4 or more carbon atoms in the organic electrolytic solution is 0.1 part by volume or more and 10 volumes by volume with respect to 100 parts by volume of the electrolytic solution solvent. parts or less of any of claims 1-9
Organic Electrolyte Organic electrolyte for secondary batteries .