JP3275998B2 - Organic electrolyte secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic electrolyte secondary battery, and more particularly, to an organic electrolyte secondary battery having excellent safety.

[0002]

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

[0003] As a solvent for an organic electrolytic solution of this battery (hereinafter simply referred to as "electrolyte solution" except when the battery is referred to), cyclic esters such as ethylene carbonate and dimethyl carbonate, diethyl carbonate, propionate have been used. It has been used in combination with a chain ester such as methyl acid.

However, as this organic electrolyte secondary battery has been studied for the purpose of further improving its safety,
If a chain ester is used as the main solvent as the solvent for the electrolyte, or if the negative electrode has a large chargeable / dischargeable capacity, the internal structure of the battery may cause an internal short circuit or It was found that the safety in the case of stabbing tended to decrease.

[0005] Usually, measures are taken to prevent overcharging by a protection circuit or the like so as not to cause an internal short circuit, and a normal internal short circuit does not cause an abnormal situation because the battery only generates heat. In addition, nail penetration rarely occurs and is unlikely to occur unless the user intentionally performs it. As a possibility, it is assumed that the battery is partially crushed due to an impact accident or the like.

For this purpose, a crush test of the battery is performed, but it is usually safe. However, it is difficult to say that it is safe enough to test only a few dozen, but it is desirable to confirm the safety by conducting a test under more dangerous conditions.

[0007] On the other hand, in the nail penetration test, the battery is reliably short-circuited in a smaller portion than the battery crush test. Easy to be. For this reason, variations in the fuses (clogging due to melting) of the separator are likely to occur, and the heat generated by the reaction between the electrolyte and the negative electrode at the short-circuited portion increases. Therefore, the nail penetration test is effective as a severe safety test. Further, when the nail penetration test is performed at a high temperature of 40 ° C. than at room temperature, the battery easily 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 a 釘 nail penetration, the short-circuit portion is reduced, and the current is more concentrated and heat is easily generated. Therefore,
To obtain higher safety, 1/1
(2) It is desirable to be able to withstand the nail penetration test to some extent.

[0008]

By the way, when a compound such as carbon capable of deintercalating lithium is used for the negative electrode, the reactivity with the electrolytic solution at a higher temperature is much lower than when metal lithium is used. Safety is improved. However , in order to improve the safety, it is essential to have 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.

Regarding the reaction with the electrolyte on the surface of the negative electrode, see D. Aurbach et al. Report that organic carbonates (ROCO ₂ Li), Li ₂ CO ₃ , alkoxides (ROLi) and the like are formed on carbon [J. Electrochemical Soc. , V
ol142 (No. 9), p2882 (1995)].
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 is 1: 1.
It is reported that higher levels have an adverse effect on cycling characteristics. In addition, when the present inventors have carried out an investigation,
Especially when the ratio of the chain esters such as diethyl carbonate is increased, the especially the proportion of the linear ester increases with methyl group, safety in the short and nailing has been found that tend to be lowered.

Accordingly, an object of the present invention is to solve the problems related to the safety of the conventional organic electrolyte secondary battery and to provide an organic electrolyte secondary battery having excellent safety.

[0011]

SUMMARY OF THE INVENTION The present invention provides an open circuit for charging.
A positive electrode using a lithium composite oxide having a voltage of 4 V or more based on Li, a negative electrode having a film formed on the surface by partially reacting with an electrolytic solution, and chain esters including a chain ester having a methyl group. In an organic electrolytic solution secondary battery having an electrolytic solution as a main solvent, the above problem has been solved by including a nonionic aromatic compound having an alkyl group having 4 or more carbon atoms in the electrolytic solution. is there.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As the nonionic aromatic compound having an alkyl group and having 4 or more carbon atoms , for example, tri-2-ethylhexyl trimellitate [(C ₆ H ₃ (COOC ₈ H _{17) 3]} trimellitic acid ester or its derivative, such as, dibutyl phthalate _{[(C 6 H 4 (COOC 4} H 9) 2 ], tertiary or isobutyl benzene _{(C 6 H 5 -C 4 H} 9),
Cyclohexyl benzene _{(C 6 H 11 -C 6 H} 5) can be mentioned.

Alkyl groups of the non-ionic aromatic compound, it is necessary that the carbon number is 4 or more, more Nozomu <br/> Mashiku is 5 or more carbon atoms. Further, the alkyl group may be directly bonded to the benzene ring.
More preferably, it is attached to the benzene ring via a group. That is, the longer the alkyl group and the presence of the COO group, the greater the barrier effect on the negative electrode surface (the effect of suppressing a rapid reaction between the electrode and the electrolyte at a high temperature). Here, non-ionic in the non-ionic aromatic compound means that the compound does not have a cation part or an anion part in a molecule.

In the present invention, the content of the nonionic aromatic compound having the specific alkyl group in the electrolytic solution is preferably 0.1 part by volume or more based on 100 parts by volume of the electrolytic solution solvent. , 0.2 volume parts or more, and most preferably 0.5 volume parts or more. When the nonionic aromatic compound having the specific alkyl group is a solid, a value obtained by converting the density into a volume is used. The content of the nonionic aromatic compound having the specific alkyl group in the electrolytic solution is preferably 10 parts by volume or less, more preferably 2 parts by volume or less, with respect to 100 parts by volume of the electrolytic solution solvent. The capacity part or less is most desirable.

If the content of the nonionic aromatic compound having the specific alkyl group in the electrolyte is smaller than the above, the safety cannot be sufficiently improved, and the specific alkyl group cannot be used. If the content of the nonionic aromatic compound in the electrolyte is higher than the above, the cycle characteristics and load characteristics of the battery may be deteriorated.

[0016]

[0017]

The present inventors have studied in detail the effect of adding an aromatic compound to an electrolyte on the safety of a battery. To explain this in detail, the present inventors first performed a nail penetration test of a lithium ion battery assuming an internal short circuit or the like. It was found that the risk increased as the density increased.

Compounds capable of deintercalating lithium, such as carbon materials, are usually used for the negative electrodes of these batteries.
If the negative electrode is overcharged and some lithium is electrodeposited, about 1
From around 00 ° C., an exothermic reaction occurs between the electrolytic solution and electrodeposited lithium or a carbon material into which lithium is inserted. Meanwhile, charging
In the positive electrode using a lithium composite oxide having an open circuit voltage of 4 V or more based on Li when lithium is desorbed, the temperature at which the reaction starts with the electrolytic solution decreases, and the heat of reaction of the negative electrode causes a thermal runaway temperature of the positive electrode. If the temperature rises to, the battery will generate abnormal heat.

Due to such a heat generation phenomenon accompanied by a continuous reaction, when the chargeable / dischargeable capacity of the negative electrode of the battery under normal use conditions exceeds 85 mAh / cm ³ per unit volume of the battery, the battery becomes excessive. Safety when charged is reduced. In other words, the greater the dischargeable capacity per unit volume of the negative electrode, the greater the amount of heat generated per unit volume of the battery if heat is generated during overcharge, and the higher the possibility that the battery temperature will rise to the thermal runaway temperature of the positive electrode. It becomes. 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. Moreover, since it becomes much calorific value when the battery size is large, it is necessary to suppress the exothermic reaction between the negative electrode and the electrolyte, a non-ionic aromatic having the specific alkyl <br/> Le group of the invention The effect of including the compound is remarkably exhibited. The size of the cell is 10 cm ³ or more,
In particular, when it is 15 cm ³ or more, the effect of the present invention is more remarkably exhibited.

It is known to add a nonflammable solvent, dissolve a polymer, or add an aromatic compound to the electrolytic solution in order to improve the safety of the battery. By using a nonionic aromatic compound for a battery containing a chain ester containing a chain ester having a methyl group as a main solvent, a particularly excellent effect in improving safety has been found. In the present invention, the specific non-ion
The reason why the safety can be improved by adding a reactive aromatic compound is considered as follows.

By preparing the negative electrode with a compound capable of deintercalating lithium such as a carbon material, the reactivity between the electrolyte and the negative electrode at a high temperature is suppressed as compared with the case where lithium is used. As the dischargeable capacity increases, the reactivity with the electrolytic solution increases, the amount of heat generated when the battery generates heat and the reaction between the negative electrode and the electrolytic solution occurs increases, and the temperature easily rises. However, when the aromatic compound is added to the electrolyte, the aromatic compound is adsorbed on the surface of the negative electrode and suppresses the direct contact between the surface of the negative electrode and the chain ester. It is believed that the reactivity is reduced and the temperature rise is limited. And
It was also found that the aromatic compound having a specific alkyl group was more effective. The details will be clarified in Examples described later.

Chain ester used as main solvent of electrolyte
Classes are organic solvents having a chain COO-bond, such as, for example, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propionate. Because the main solvent, a chain ester in all electrolyte solvent containing these chain esters is meant that more than 50% by volume. Tend to chain esters is reduced battery safety in the nail penetration test exceeds 65 vol%, the effect of adding the non-ionic aromatic compound increases with an alkyl group. The effect of the addition of the chain esters are nonionic aromatic compound having more than the alkyl group of 70 vol% is more increased, the non-ionic having an alkyl group as chain esters is more than 75 vol% The effect of adding the aromatic compound is further increased. Further, since the chain esters tends to lower the safety of the battery may have a methyl group, the effect of adding the nonionic aromatic compound having an alkyl group is much more remarkable.

Further, when used in mixing the chain ester dielectric constant below is high such ester (dielectric constant 30 or higher), than the case of using only chain esters, the load characteristics of the cycle characteristics and battery Because of the improvement, it becomes more desirable as a battery. Examples of such an ester having a high dielectric constant include, for example, propylene carbonate (P
C), ethylene carbonate (EC), butylene carbonate (BC), gamma-butyrolactone (γ-B
L), ethylene glycol sulphite (EGS) and the like, particularly preferably having a cyclic structure, particularly preferably a cyclic carbonate, and most preferably ethylene carbonate (EC).

The ester having a high dielectric constant is preferably less than 40% by volume of the total solvent of the electrolytic solution, more preferably 30% by volume.
% By volume or less, more preferably 25% by volume or less.
The improvement of the safety by these esters having a high dielectric constant becomes remarkable when the ester having a high dielectric constant becomes 10% by volume or more in the entire solvent of the electrolytic solution, and becomes further remarkable when it reaches 20% by volume. .

[0026] The above can be used in combination of solvents and chain esters in addition to high dielectric constant esters, such as 1,2-dimethoxyethane (DME), 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, and the like can also be used.

As the electrolyte of the electrolytic solution, for example, LiC
10 ₄ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , Li
SbF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , L
iCF ₃ CO ₂ , Li ₂ C ₂ F ₄ (SO ₃ ) ₂ , LiN
(CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , Li
C _n F _{2n + 1} SO ₃ (n ≧ 2), LiN (Rf ₃ OS
O ₂ ) ₂ [Rf is a fluoroalkyl group] or the like may be used alone or in combination of two or more.
F ₆ and LiC ₄ F ₉ SO ₃ are desirable because of their good charge / discharge characteristics. The concentration of the electrolyte in the electrolytic solution is not particularly limited, but it is desirable that the concentration be 1 mol / l or more, since safety is improved.
/ L or more is more desirable. Further, when the concentration of the electrolyte in the electrolytic solution is 1.7 mol / l or less, good electric characteristics are maintained, and it is more preferable that the concentration is 1.5 mol / l or less.

The lithium composite oxide used as the positive electrode active material has an open circuit voltage at the time of charging of 4 V or more on the basis of Li.
Although this is a composite oxide of titanium,
Lithium composite oxide whose pressure shows 4 V or more based on Li
Te is, for example, lithium cobalt oxide such as LiCoO _2, lithium manganese oxide such as LiMn ₂ O _4,
A lithium nickel oxide such as LiNiO ₂ can be used , and the open circuit voltage during such charging is 4 based on Li.
Use lithium composite oxide showing V or more as positive electrode active material
If you were the Ru high energy density is obtained.

For the positive electrode, for example, a mixture obtained by appropriately adding a conductive additive or a binder such as polyvinylidene fluoride to the positive electrode active material is formed into a molded body using a current collector material such as aluminum foil as a core material. Finished products are used.

[0030] LiCoO ₂ and LiNiO ₂ were charged in Japanese
Has a lower temperature than LiMn ₂ O _{4 for} initiating a reaction with the electrolytic solution, and tends to reach the thermal runaway temperature of the positive electrode due to the heat generated by the negative electrode, so that the effect of the present invention is more remarkably exhibited.

The material used for the negative electrode may be any material capable of doping and undoping lithium ions. Examples of the material include graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, meso materials. Carbon material such as carbon microbeads, carbon fiber, activated carbon or S
An alloy of lithium with i, Sn, In, or the like, or an oxide of Si, Sn, In, or the like that can be charged and discharged at a low potential close to Li can be used.

When a carbon material is used for the negative electrode, the carbon material desirably has the following characteristics. That is, the interlayer distance d ₀₀₂ of the (002) plane is desirably 3.5 ° or less, more desirably 3.45 ° or less, and further desirably 3.4 ° or less. The crystallite size Lc in the c-axis direction is desirably 30 ° or more, more desirably 80 ° or more, and further desirably 250 ° or more. And the average particle size is 8 to 15 μm, especially 10 to 10 μm.
13 μm is desirable, and the purity is desirably 99.9% or more.

[0033]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.

Example 1 Methyl ethyl carbonate and ethylene carbonate were mixed in a volume ratio of 76:24, and tri-2-ethylhexyl trimellitate [(C ₆ H ₃ (COOC ₈ H) was added to 100 parts by volume of the mixed solvent. ₁₇ ) ₃ ;
M ") was added and mixed, and LiPF ₆ was dissolved at 1.4 mol / l to give a composition of 1.4 mol / l.
LiPF ₆ / EC: MEC (24:76 volume ratio) +1
An electrolytic solution represented by% TOTM was prepared.

EC in the above electrolyte is an abbreviation for ethylene carbonate, and MEC is an abbreviation for methyl ethyl carbonate. Therefore, the above-mentioned electrolyte solution of 1.4mo
1 / l LiPF ₆ / EC: MEC (24:76 volume ratio) + 1% TOTM is methyl ethyl carbonate 76
It shows that 1.4 mol / l of LiPF ₆ was dissolved in a mixed solvent of 20% by volume of ethylene carbonate and 24% by volume of ethylene carbonate, and 1 part by volume of TOTM was dissolved in 100 parts by volume of the mixed solvent. .

Separately, LiC as a positive electrode active material
Phosphorous graphite is added to oO ₂ as a conductive additive in a weight ratio of 100: 7.
The mixture was mixed with a solution prepared by dissolving polyvinylidene fluoride in N-methylpyrrolidone to form a slurry. After passing the positive electrode mixture slurry through a 70-mesh net to remove a large one,
The positive electrode current collector made of a μm aluminum foil was uniformly applied to both sides and dried, then compression-molded by a roller press, cut, and then welded to a lead body to produce a belt-shaped positive electrode.

Next, a graphite-based carbon material (interlayer distance d ₀₀₂ = 3.37 °, crystallite size Lc in the c-axis direction =
90 parts by weight of a graphite-based carbon material having characteristics of 950 °, an average particle diameter of 10 μm, and a purity of 99.9%) were mixed with a solution obtained by dissolving 10 parts by weight of vinylidene fluoride in N-methylpyrrolidone to form a slurry. The negative electrode mixture slurry was passed through a 70-mesh net to remove large particles, and then uniformly applied to both surfaces of a negative electrode current collector made of a strip-shaped copper foil having a thickness of 10 μm, dried, and then rolled. After compression molding with a press machine and cutting, the lead body was welded to produce a strip-shaped negative electrode.

The above-mentioned band-shaped positive electrode is overlapped on the above-mentioned band-shaped negative electrode via a microporous polyethylene film having a thickness of 25 μm, and is spirally wound into a spiral electrode body. And the lead bodies of the positive electrode and the negative electrode were welded. Here, the positive electrode of the active material-containing mixture per unit volume of the opposed parts of the positive electrode and the negative electrode /
The negative electrode weight ratio was 2.06. The charge and discharge capacity of the negative electrode is
The battery was charged under normal charging conditions (charged at 1400 mA;
After reaching 1 V, the charging operation at a constant voltage of 4.1 V
(Performed for 30 minutes), the value was 85 mAh / cm ³ .

Next, the electrolytic solution was poured into the battery case, and after the electrolytic solution sufficiently permeated into the separator and the like, sealing was performed, preliminary charging and aging were performed, and a cylindrical organic electrolytic solution having a structure shown in FIG. A secondary battery was manufactured.

The battery shown in FIG. 1 will be described briefly. 1 is the positive electrode and 2 is the negative electrode. However, FIG. 1 does not show the current collectors used for producing the positive electrode 1 and the negative electrode 2 in order to avoid complication, and the positive electrode 1 and the negative electrode 2 are spirally interposed through the separator 3. Wound, as a spiral electrode body, together with the electrolyte,
It is housed in a battery case 4 made of stainless steel.

As described above, the electrolyte contains TOTM (that is, tri-2-ethylhexyl trimellitate), and the battery case 4 also serves as a negative electrode terminal, and an insulator 5 Are arranged, and the insulator 6 is also arranged on the spiral electrode body. A sealing body 8 is arranged at 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, a reversible vent mechanism for preventing the gas generated inside the battery from being ruptured under a high pressure by discharging the gas generated inside the battery to a certain pressure when the gas is raised to a certain pressure and preventing the battery from being ruptured under a high pressure. Have been.

Example 2 Instead of TOTM, dibutyl phthalate [C ₆ H ₄ (CO
A cylindrical organic electrolyte secondary battery was fabricated in the same manner as in Example 1 except that OC ₄ H ₉ ) ₂ ] was used.

[0043]

[0044]

Comparative Example 1 A cylindrical organic electrolyte secondary battery was produced in the same manner as in Example 1 except that the electrolyte did not contain a nonionic aromatic compound having an alkyl group.

Comparative Example 2 A cylindrical organic electrolyte secondary battery was prepared in the same manner as in Comparative Example 1 except that the volume ratio of ethylene carbonate (EC) to methyl ethyl carbonate (MEC) was 1: 2. Produced.

Comparative Example 3 A cylindrical organic electrolyte secondary battery was prepared in the same manner as in Comparative Example 1 except that the ratio of ethylene carbonate (EC) to methyl ethyl carbonate (MEC) was changed to 1: 1 by volume. Produced.

COMPARATIVE EXAMPLE 4 An electrode was prepared in which the weight ratio of the positive electrode / negative electrode of the active material-containing mixture per unit volume of the positive electrode and the negative electrode was 1.95 per unit volume of the positive electrode and the negative electrode at the time of electrode preparation. Total thickness,
A cylindrical organic electrolyte secondary battery was produced in the same manner as in Comparative Example 3, except that a spirally wound electrode body was made to have the same winding diameter and a negative electrode having a charge / discharge capacity of 1300 mAh was produced. The chargeable / dischargeable capacity of the negative electrode was 79 mAh / cm ³ . Comparative Example 5 Dimethyl phthalate [C ₆ H ₄ (CO
OCH ₃ ) ₂ ] except that OCH ₃ ) ₂ ] was used.
A cylindrical organic electrolyte secondary battery was produced. Comparative Example 6 Example 1 was repeated except that toluene was used instead of TOTM.
Similarly, a cylindrical organic electrolyte secondary battery was produced.

After discharging the batteries of Examples 1 and 2 and Comparative Examples 1 to 6 to 2.75 V at 1400 mA, 140
After the battery was charged at 0 mA and reached 4.18 V, the battery was charged for 2 hours and 30 minutes under the condition of maintaining a constant voltage of 4.18 V. Thereafter, the battery was placed in a constant temperature bath at 40 ° C., taken out 2 hours later, placed on a wooden and grooved battery holder, and a stainless steel nail having a shaft diameter of 3 mm was perpendicular to the center of the side of the battery. Immediately, the battery was stabbed to a depth of の of the outer diameter of the battery to check for abnormal heat generation. Table 1 shows the results.

Examples 1 and 2 and Comparative Examples 1 to 6
In Table 1, the number of batteries subjected to the test is shown in the denominator, and the number of batteries having abnormal heat generation is shown in the numerator, and the ratio of abnormal heat generation is shown in Table 1. 1 at 40 ° C
/ 2 nail penetration test is a test of in a very severe conditions as a test to confirm the safety.

[0051]

[Table 1]

[0052] As shown in Table 1, Example 1-2, methylate
Chain esters including a chain ester having a hydroxyl group
Comparative Example 1 in which the main solvent of the electrolytic solution exceeded the volume% but did not contain the nonionic aromatic compound, and Comparative Examples 5 to 6 which contained the nonionic aromatic compound having a methyl group. The rate of abnormal heat generation has been reduced to less than half
Is seen to improve the safety in the nail penetration test by the number of carbon atoms in the electrolytic solution to contain a non-ionic aromatic compound having 4 or more alkyl groups. Especially non-io
The alkyl group of the aromatic aromatic compound has 5 or more carbon atoms
In Example 1, no abnormal heat generation occurred. In addition, when the number of chain esters such as methyl ethyl carbonate is small as in Comparative Examples 2 to 3, or when the chain ester has only an ethyl group, the safety is good, and the nonionic aromatic compound having an alkyl group is good. Tends to be less effective. Furthermore, even when the charge / discharge capacity of the negative electrode is small as in Comparative Example 4, the safety is improved, and the effect of adding the nonionic aromatic compound having an alkyl group is reduced.

[0053]

As described above, according to the present invention, the charging
Positive electrode using lithium composite oxide whose open circuit voltage shows 4 V or more on the basis of Li, a negative electrode partially reacted with an electrolytic solution to form a film on the surface, and a chain containing a methyl group-containing chain ester In an organic electrolyte secondary battery having an electrolyte containing an ester as a main solvent, the electrolyte has 4 carbon atoms.
By adding a nonionic aromatic compound having at least two alkyl groups, the safety of the battery could be improved. In particular, when the chargeable / dischargeable capacity of the negative electrode exceeds 85 mAh / cm ³ per unit volume of the battery, the effect of improving safety is great. When a nonionic aromatic compound having an alkyl group having 5 or more carbon atoms was used, the effect of improving safety was large.

[Brief description of the drawings]

FIG. 1 is a partial sectional perspective view schematically showing an example of an organic electrolyte secondary battery according to the present invention.

[Explanation of symbols]

 1 positive electrode 2 negative electrode 3 separator

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-22069 (JP, A) JP-A-5-36439 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/40

Claims (5)

(57) [Claims] An open circuit voltage during charging is 4 V or more based on Li.
Positive electrode using lithium composite oxide showing , negative electrode partly reacted with organic electrolyte to form a film on the surface, and organic electrolysis using chain esters containing chain ester having methyl group as main solvent An organic electrolyte secondary battery having a liquid, wherein the organic electrolyte contains a nonionic aromatic compound having an alkyl group having 4 or more carbon atoms. 2. The method according to claim 1, wherein the chain ester is a chain ester having a methyl group, and the chargeable / dischargeable capacity of the negative electrode is 85 mAh / cm ³ or more per unit volume of the battery. Organic electrolyte secondary battery. 3. The organic electrolyte secondary according to claim 1, wherein the nonionic aromatic compound having an alkyl group is a nonionic aromatic compound having an alkyl group having 5 or more carbon atoms. battery. 4. The organic electrolyte secondary battery according to claim 3, wherein the alkyl group of the nonionic aromatic compound having an alkyl group and the benzene ring are bonded via a COO group. 5. The organic electrolyte secondary battery according to claim 4, wherein the nonionic aromatic compound having an alkyl group is trimellitic acid ester or a derivative thereof.