JP2003308875A - Nonaqueous secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous secondary battery having superior high- temperature shelf life. <P>SOLUTION: The nonaqueous secondary battery 1 comprises a nonaqueous electrolyte containing at least one type selected from a sultone compound, cyclic sulfate, and vinylene carbonate and at least one type selected from an alkyl benzene derivative having tertiary carbon neighboring phenyl groups, a cycloalkyl benzene derivative, and a biphenyl derivative, whereby coatings are formed on a positive electrode 3 and a negative electrode 4. The coatings suppress the high-temperature decomposition of the electrolyte, resulting in improved high-temperature shelf life. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous secondary battery.

[0002]

2. Description of the Related Art A non-aqueous secondary battery consisting of a positive electrode, a negative electrode and a non-aqueous electrolytic solution, which can be repeatedly used by charging, is
Since it has a higher energy density than aqueous secondary batteries such as lead-acid batteries and nickel-cadmium batteries, it has been actively researched as a power source for consumer mobile phones, portable devices, personal digital assistants, and the like.

Among the non-aqueous secondary batteries, a positive electrode containing a positive electrode active material capable of reversibly electrochemically reacting with lithium ions, and a negative electrode containing a negative electrode active material capable of reversibly occluding and releasing lithium ions. A lithium-ion battery composed of a non-aqueous electrolyte containing a lithium salt has high voltage, high energy density, excellent cycle life, high safety, and the like, and thus has been actively researched.

As the non-aqueous electrolyte, a mixed solvent of a high dielectric constant solvent such as ethylene carbonate or propylene carbonate and a low viscosity solvent such as dimethyl carbonate or diethyl carbonate is generally used in LiPF ₆ or LiB.
A solution in which a supporting salt such as F ₄ is dissolved is used.

The above non-aqueous secondary battery is required to have excellent high temperature storage characteristics. This is because, for example, the non-aqueous secondary battery used in a mobile phone left in an automobile parked outdoors during the midsummer day may be exposed to a high temperature environment deviating from the normal use environment. Because it is possible.

However, when the non-aqueous electrolyte is constructed as described above, when a battery in a charged state is left at a high temperature, the battery swells, the discharge capacity decreases, etc.
There is a problem that the high temperature storage characteristics are deteriorated.

As described above, the reason why the battery swells is that the vapor pressure of the electrolytic solution rises because the battery is left in a high temperature environment and that gas is generated due to decomposition of the electrolytic solution on the electrodes. Conceivable. Among these, regarding the generation of gas on the electrode, for example, in the case of a binary solvent of EC and EMC, the generation of methane gas or the like at the negative electrode is the main cause at 70 ° C. or lower, and the temperature exceeding 70 ° C. It has been found from our previous studies that the higher the concentration, the more the cause of carbon dioxide gas generation in the positive electrode.

Further, as described above, the discharge capacity decreases because the decomposition reaction of the electrolytic solution on the positive electrode and the negative electrode, the reaction resistance of the electrode increases, the electric conductivity of the electrolytic solution decreases, the separator clogging, It is considered that the gap between the electrodes is increased due to the swelling of the battery.

The deterioration of the high temperature storage characteristics, such as the swelling of the battery and the reduction of the remaining discharge capacity, is more serious as the storage temperature is higher and the storage time is longer.

[0010]

The present invention was completed in view of the above circumstances, and an object of the present invention is to provide a non-aqueous secondary battery having excellent high temperature storage characteristics.

[0011]

[Means for Solving the Problems and Actions / Effects] As means for achieving the above object, the invention of claim 1 is
In a non-aqueous secondary battery consisting of a positive electrode, a negative electrode, and a non-aqueous electrolyte, the non-aqueous electrolyte is at least one selected from a sultone compound, a cyclic sulfate, and vinylene carbonate, and a tertiary carbon adjacent to a phenyl group. And at least one selected from the group consisting of an alkylbenzene derivative, a cycloalkylbenzene derivative, and a biphenyl derivative.

When the non-aqueous electrolyte contains at least one selected from the group consisting of sultone compounds, cyclic sulfates and vinylene carbonate, the high temperature storage characteristics at 70 ° C. or lower are improved. This is considered to be due to the following reasons.
When the above compound is contained in the electrolytic solution, the film is formed on the negative electrode by the decomposition of the compound on the negative electrode. The coating can suppress the decomposition of the electrolytic solution on the negative electrode and the generation of methane gas and the like due to the decomposition of the electrolytic solution partially decomposed on the positive electrode.

On the other hand, the non-aqueous electrolyte contains at least one selected from the group consisting of an alkylbenzene derivative having a tertiary carbon adjacent to a phenyl group, a cycloalkylbenzene derivative and a biphenyl derivative, so that the nonaqueous electrolyte is left at a high temperature in a temperature range of more than 70 ° C. The characteristics are improved. This is considered to be due to the following reasons. When the above compound is contained in the electrolytic solution, the compound is decomposed and polymerized on the positive electrode to form a film on the positive electrode. The coating can suppress the decomposition of the electrolytic solution on the positive electrode and the generation of carbon dioxide gas and the like due to the decomposition of the electrolytic solution partially decomposed on the negative electrode.

The non-aqueous electrolyte is a sultone compound,
Cyclic sulfate, at least one selected from vinylene carbonate, and an alkylbenzene derivative having a tertiary carbon adjacent to a phenyl group, a cycloalkylbenzene derivative, by containing at least one selected from a biphenyl derivative, each of the above compounds alone The high temperature storage property is improved as compared with the case where it is used. This is considered to be due to the following reasons.

When the above compound is not used at all, decomposition of the electrolytic solution proceeds on the electrode placed under a high temperature environment, and gases such as methane gas and carbon dioxide gas are generated depending on the temperature. At this time, not only the electrolytic solution on the electrode but also the electrolytic solution partially decomposed on the other electrode is considered to be decomposed together.

That is, even when a film is formed on the negative electrode in a temperature range of 70 ° C. or lower to suppress gas generation on the negative electrode, the electrolytic solution partially decomposed at the negative electrode is decomposed at the positive electrode to generate carbon dioxide. Causes generation of gas, etc., 70
Even when a film is formed on the positive electrode in a temperature range exceeding ℃ to suppress gas generation on the positive electrode, the cause of generation of methane gas or the like due to decomposition of the electrolytic solution partially decomposed at the positive electrode at the negative electrode Become.

The non-aqueous electrolyte is a sultone compound,
An electrode having a coating formed by containing at least one selected from cyclic sulfates and vinylene carbonate and at least one selected from alkylbenzene derivatives having a tertiary carbon adjacent to a phenyl group, cycloalkylbenzene derivatives, and biphenyl derivatives. It is possible to suppress decomposition of the electrolytic solution. Not only can the partially decomposed electrolytic solution be further prevented from being decomposed at the other electrode. As a result, at least one selected from a sultone compound, a cyclic sulfuric acid ester, and at least one selected from vinylene carbonate, or an alkylbenzene derivative having a tertiary carbon adjacent to a phenyl group, a cycloalkylbenzene derivative, and a biphenyl derivative. Compared with the case of including, the high-temperature storage property is improved more than the sum of the performances of both.

The addition amount of the compound selected from the sultone compound, the cyclic sulfuric acid ester and the vinylene carbonate is to effectively suppress the decomposition of the electrolytic solution in the high temperature environment without lowering the initial discharge capacity on the negative electrode. In addition, it is preferably 0.1% by weight or more and 5% by weight or less with respect to the total amount of electrolytic solution.
Particularly, 0.5% by weight or more and 2% by weight or less is preferable.

The addition amount of the compound selected from the alkylbenzene derivative having a tertiary carbon adjacent to the phenyl group, the cycloalkylbenzene derivative and the biphenyl derivative is
In order to effectively suppress decomposition of the electrolytic solution on the positive electrode in a high temperature environment, 2% by weight or more with respect to the total amount of the electrolytic solution 4
It is preferably less than or equal to weight%.

According to a second aspect of the present invention, in the first aspect, the sultone compound is propane sultone,
It is characterized by being either propene sultone or butane sultone.

By using the above substances as the sultone compound, a stable coating film can be formed on the negative electrode, so that the high temperature storage property is improved.

A third aspect of the present invention is characterized in that, in the first or second aspect, the cyclic sulfate is one of glycol sulfate and propylene glycol sulfate.

By using the above substances as the cyclic sulfate, a stable coating film can be formed on the negative electrode, so that the high temperature storage property is improved.

The invention of claim 4 is the same as in any one of claims 1 to 3, wherein the alkylbenzene derivative having a tertiary carbon adjacent to the phenyl group is cumene or 1,3-diisopropylbenzene. , 1,4
-Diisopropylbenzene, 1-methylpropylbenzene, 1,3-bis (1-methylpropyl) benzene,
It is characterized by being any of 1,4-bis (1-methylpropyl) benzene.

By using the above substances as the alkylbenzene derivative having a tertiary carbon adjacent to the phenyl group, a stable film can be formed on the positive electrode.
High temperature storage characteristics are improved.

The invention of claim 5 is characterized in that, in any one of claims 1 to 4, the cycloalkylbenzene derivative is either cyclohexylbenzene or cyclopentylbenzene.

By using the above substances as the cycloalkylbenzene derivative, a stable coating film can be formed on the positive electrode, so that the high temperature storage property is improved.

A sixth aspect of the present invention is the method according to any one of the first to fifth aspects, wherein the biphenyl derivative is biphenyl, 2-fluorobiphenyl, 2-bromobiphenyl or 2-chlorobiphenyl. Is characterized in that.

By using the above substances as the biphenyl derivative, a stable coating film is formed on the positive electrode, so that the high temperature storage property is improved.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view of a prismatic non-aqueous secondary battery that is an embodiment of the present invention. This prismatic non-aqueous secondary battery 1 comprises a positive electrode 3 formed by applying a positive electrode mixture to a positive electrode current collector made of aluminum foil, and a negative electrode 4 formed by applying a negative electrode mixture to a negative electrode current collector made of copper foil. And a flat wound electrode group 2 wound with a separator 5 interposed therebetween and a non-aqueous electrolyte solution in a battery case 6 and having a width of 30 mm, a height of 48 mm and a thickness of 4 mm.

A battery lid 7 provided with a safety valve 8 is attached to the battery case 6 by laser welding, and a negative electrode terminal 9 is attached.
Is connected to the negative electrode 4 via the negative electrode lead 11, and the positive electrode 3 is connected to the battery lid via the positive electrode lead 10.

Examples of the non-aqueous solvent of the non-aqueous electrolyte according to the present invention include cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate, chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, γ-
Cyclic esters such as butyrolactone and γ-valerolactone, chain esters such as methyl acetate and methyl propionate, cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran and tetrahydropyran, chain ethers such as dimethoxyethane and dimethoxymethane. Examples thereof include cyclic phosphates such as ethylene methyl phosphate and ethyl ethylene phosphate, chain phosphates such as trimethyl phosphate and triethyl phosphate, and halides of these compounds. Only one kind of these organic solvents may be selected and used, or two or more kinds thereof may be used in combination.

As the solute of the non-aqueous electrolyte according to the present invention,
Inorganic lithium salts such as LiClO ₄ , LiPF ₆ , and LiBF ₄ , LiCF ₃ SO ₃ , and LiN (CF ₃ SO ₂ ).
₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF
₃ CO) ₂ , and fluorine-containing organic lithium salts such as LiC (CF ₃ SO ₂ ) _{3 and the} like. Only one kind of these solutes may be selected and used, or two or more kinds thereof may be used in combination.

The sultone compound to be added to the non-aqueous electrolyte according to the present invention may be selected from propane sultone, propene sultone and butane sultone.

As the cyclic sulfate ester added to the electrolytic solution according to the present invention, one selected from glycol sulfate and propylene glycol sulfate can be used.

Vinylene carbonate can be added to the non-aqueous electrolyte according to the present invention. Examples of the alkylbenzene derivative having a tertiary carbon adjacent to the phenyl group added to the non-aqueous electrolyte include cumene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, 1-methylpropylbenzene and 1,3-bis. (1-Methylpropyl) benzene, 1,4-bis (1-methylpropyl)
Any selected from benzene can be used.

As the cycloalkylbenzene derivative added to the non-aqueous electrolyte according to the present invention, any one selected from cyclohexylbenzene and cyclopentylbenzene can be used.

As the biphenyl derivative added to the non-aqueous electrolyte according to the present invention, any one selected from biphenyl, 2-fluorobiphenyl, 2-bromobiphenyl and 2-chlorobiphenyl can be used. Among these, 2-fluorobiphenyl, 2-bromobiphenyl and 2-chlorobiphenyl are more preferable, and further 2
-Fluorobiphenyl is particularly preferred.

As the separator, a porous polymer film or nonwoven fabric such as polyethylene, polypropylene or polyester, a nonwoven fabric such as glass fiber, a nonwoven fabric of glass fiber and polymer fiber or the like can be used.

The positive electrode active material has a layered rock salt structure
General formula LiMO_Two(M is a transition metal)
Um-transition metal composite oxides and lithium with spinel structure
A um-manganese composite oxide can be used. Also,
TiO_Two, TiS_Two, V_TwoO ₅, MnO_Two, MoO_ThreeNa
Use any metal chalcogenide that does not contain lithium.
You can However, the metal chalcogenide is used.
In this case, completely discharge these positive electrode active materials beforehand, and
Is partially discharged and doped with lithium ions
It is desirable to keep.

The type of the conductive agent is not particularly limited, and it may be a metal or a nonmetal. As a metal conductive agent,
Examples thereof include materials composed of metal elements such as Cu and Ni. Examples of the non-metal conductive agent include carbon materials such as graphite, carbon black, acetylene black and Ketjen black.

The type of binder is not particularly limited as long as it is a material that is stable with respect to the solvent and electrolytic solution used during electrode production. Specifically, polyethylene, polypropylene,
Resin-based polymers such as polyethylene terephthalate, aromatic polyamide, cellulose, styrene-butadiene rubber,
Rubber-like polymers such as isoprene rubber, butadiene rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymers and hydrogenated products thereof, styrene-ethylene-butadiene-styrene block copolymers and hydrogenated products thereof, styrene -Isoprene-styrene block copolymer and thermoplastic elastomeric polymers such as hydrogenated products thereof, syndiotactic 1,2-polybutadiene, ethylene-vinyl acetate copolymer, propylene-α-olefin (having 2 to 12 carbon atoms) ) A soft resin-like polymer such as a copolymer, a fluoropolymer such as polyvinylidene fluoride, polytetrafluoroethylene, a polytetrafluoroethylene-ethylene copolymer, or the like can be used.

Further, as the binder, a polymer composition having an alkali metal ion conductivity such as lithium ion can also be used. Examples of the polymer having such ion conductivity include polyether polymer compounds such as polyethylene oxide and polypropylene oxide, cross-linked polymer compounds of polyether, polyepichlorohydrin,
Polyphosphazene, polysiloxane, polyvinylpyrrolidone, polyvinylidene carbonate, a system in which a lithium salt or an alkali metal salt mainly composed of lithium is combined with a polymer compound such as polyacrylonitrile, or propylene carbonate, ethylene carbonate,
A system containing an organic compound having a high dielectric constant such as γ-butyrolactone can be used. These materials may be used in combination.

Examples of the positive electrode current collector include Al, Ta and N.
Examples thereof include b, Ti, Hf, Zr, Zn, W, Bi, and alloys containing these metals. These metals form a passivation film on the surface by anodic oxidation in an electrolytic solution. Therefore, it is possible to effectively prevent the non-aqueous electrolyte from oxidatively decomposing at the liquid contact portion between the positive electrode current collector and the electrolytic solution. As a result, the cycle characteristics of the non-aqueous secondary battery can be effectively improved. Among the above metals, Al, Ti, Ta and alloys containing these metals can be preferably used. In particular, Al and its alloys have a low density, so that the mass of the positive electrode current collector can be reduced as compared with the case of using other metals. for that reason,
Since the energy density of the battery can be improved,
Particularly preferred.

When the positive electrode mixture obtained as described above is applied to the positive electrode current collector, it can be carried out by a known means. When the mixture is in the form of a slurry, it can be applied onto the current collector using, for example, a doctor blade. When the mixture is in the form of paste, it can be applied onto the current collector by, for example, roller coating. If a solvent is used, the electrode can be prepared by drying to remove the solvent.

As the negative electrode active material, lithium metal, lithium
Lithium-aluminium, a substance that can inhale and release um
Um alloy, lithium-lead alloy, lithium-tin alloy, etc.
Lithium alloy, Li₅(Li_ThreeN) Lithium nitride
Carbon materials such as aluminum, graphite, coke, and organic fired materials, W
O_Two, MoO_Two, SnO_Two, SnO, TiO_Two, NbO
_ThreeTransition metal oxides such as these
Only one type of negative electrode active material may be selected and used.
However, two or more kinds may be used in combination.

The material of the negative electrode current collector is preferably a metal such as copper, nickel or stainless steel. Among them, it is more preferable to use a copper foil because it is easily processed into a thin film and is inexpensive.

The method for producing the negative electrode is not particularly limited, and the negative electrode can be produced by the same method as the above-mentioned method for producing the positive electrode.

The present invention will be described in detail below based on examples. The present invention is not limited to the following examples.

<Example 1> A positive electrode plate was composed of 8 parts by weight of polyvinylidene fluoride as a binder, 5 parts by weight of acetylene black as a conductive agent, and 87 parts by weight of lithium cobalt composite oxide as a positive electrode active material. A positive electrode mixture prepared by mixing
N-methylpyrrolidone was appropriately added to prepare a paste, and the paste was applied to both sides of an aluminum foil current collector having a thickness of 20 μm and dried.

The negative electrode plate was prepared as a paste by appropriately adding water to a negative electrode mixture prepared by mixing 95% by weight of graphite (graphite), 2% by weight of carboxymethyl cellulose and 3% by weight of styrene-butadiene rubber. Then, this was applied onto a copper foil current collector having a thickness of 15 μm and dried to manufacture.

A polyethylene microporous membrane was used as the separator. Further, 1 mol / l of LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate and ethylmethyl carbonate were mixed in a volume ratio of 3: 7 in the electrolytic solution, and propane sultone was added in an amount of 0. 5% by weight
And 3% by weight of cyclohexylbenzene were used.

Using the above components, 12 cells of a non-aqueous secondary battery having a width of 30 mm, a height of 48 mm and a thickness of 4 mm were produced.

<Examples 2 to 66 and Comparative Examples 1 to 13> Regarding the non-aqueous secondary batteries of Examples 2 to 18, the substances added to the electrolytic solution are shown in Table 1 instead of propane sultone and cyclohexylbenzene. Twelve non-aqueous secondary batteries were produced in the same manner as in Example 1 except that the substances shown were added.

Regarding the non-aqueous secondary batteries of Examples 19 to 30, Example 1 was repeated except that the substances shown in Table 2 were added in place of propane sultone and cyclohexylbenzene as substances added to the electrolytic solution. Twelve non-aqueous secondary batteries were produced in the same manner as in.

Regarding the non-aqueous secondary batteries of Examples 31 to 48, Example 1 was repeated except that the substances shown in Table 3 were added in place of propane sultone and cyclohexylbenzene as substances added to the electrolytic solution. Twelve non-aqueous secondary batteries were produced in the same manner as in.

Regarding the non-aqueous secondary batteries of Examples 49 to 66, Example 1 was repeated except that the substances shown in Table 4 were added in place of propane sultone and cyclohexylbenzene as the substances added to the electrolytic solution. Twelve non-aqueous secondary batteries were produced in the same manner as in.

Regarding the non-aqueous secondary batteries of Comparative Examples 1 to 17, Example 1 was used except that the substances shown in Table 5 were added in place of propane sultone and cyclohexylbenzene as substances added to the electrolytic solution. Twelve non-aqueous secondary batteries were produced in the same manner as in.

<Measurement> (Discharge Capacity) With respect to the non-aqueous secondary batteries of Examples 1 to 66 and Comparative Examples 1 to 17, at 25 ° C., charging current 600 mA, charging voltage 4.20 V constant current-constant voltage charging. After 3 hours of charging, the discharge capacity was measured when discharged at a discharge current of 600 mA and a final voltage of 2.75 V, and this was taken as the initial discharge capacity.

(High temperature storage test) For the non-aqueous secondary batteries of Examples 1 to 66 and Comparative Examples 1 to 17, 25
At ℃, charging current 600mA, charging voltage 4.20V
Was charged for 3 hours by constant current-constant voltage charging. The battery thus charged was allowed to stand at 100 ° C. for 48 hours, and then the battery thickness was measured. Further, after the battery in the charged state was left at 60 ° C. for 30 days, the battery thickness and the discharge capacity were measured.

After being left at 60 ° C., once discharged, and then again charged and discharged, the discharge capacity measured was divided by the initial discharge capacity and multiplied by 100 to obtain the capacity retention ratio after leaving at 60 ° C. ( %) Was calculated.

The above measurement results are summarized in Tables 1 to 5.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

[Table 4]

[0067]

[Table 5]

<Results> (Swelling of Battery at 100 ° C.) When Examples 1 to 66 and Comparative Example 1 are compared, the swelling of the battery was 5.8 mm or less in Examples 1 to 66. In Example 1, 9.
It was remarkably large at 1 mm. This is because Comparative Example 1 does not include any sultone compound, cyclic sulfate, vinylene carbonate, alkylbenzene derivative having a tertiary carbon adjacent to a phenyl group, cycloalkylbenzene derivative, and biphenyl derivative, so that It is considered that the battery was swollen due to the gas generated by the decomposition of the electrolytic solution as a result of the poor formation of the film.

Examples 1 to 66 and Comparative Examples 2 to 1
Comparing No. 1 with Comparative Examples 2 to 11, the battery swelling was 6.3 mm or more, which was larger than those of Examples 1 to 66. This is considered to be due to the following reasons. In Comparative Examples 2 to 11 containing no sultone compound, cyclic sulfate and vinylene carbonate, a good film was not formed on the negative electrode. Therefore, the generation of methane gas or the like on the negative electrode cannot be suppressed at high temperatures. Therefore, even at 100 ° C., the swelling of the battery becomes large due to the methane gas or the like generated on the negative electrode.

Also in Comparative Examples 2 to 11, since the coating film was formed on the positive electrode as in Examples 1 to 66, generation of carbon dioxide gas from the positive electrode, which is the main cause of battery swelling, was suppressed. It is believed that However, it is considered that the partial decomposition reaction of the electrolytic solution is proceeding even on the positive electrode coated with the coating, although carbon dioxide gas is not generated. It is considered that such a decomposition reaction produces a substance in which a part of the electrolytic solution is decomposed.
It is considered that the substance in which a part of the electrolytic solution is decomposed in this way is further decomposed on the negative electrode to generate methane gas and the like.
In Examples 1 to 66, since the coating is also formed on the negative electrode, the above reaction is suppressed.

Comparing Examples 1 to 66 with Comparative Examples 12 to 17, Comparative Examples 12 to 17 showed a swelling of the battery of 8.3 mm or more, which was larger than that of Examples 1 to 66. This is considered to be due to the following reasons.
In Comparative Examples 12 to 17 that do not contain an alkylbenzene derivative having a tertiary carbon adjacent to a phenyl group, a cycloalkylbenzene derivative, or a biphenyl derivative, a good coating is not formed on the positive electrode. Therefore, it is impossible to suppress the generation of carbon dioxide gas on the positive electrode when the temperature is high. Therefore, when left at 100 ° C., the carbon dioxide gas generated on the positive electrode causes the battery to swell.

Also in Comparative Examples 12 to 17, since the coating film was formed on the negative electrode as in Examples 1 to 66, it is considered that the generation of methane gas and the like from the negative electrode was suppressed. However, even on the negative electrode covered with the film, although it does not reach the generation of methane gas,
It is considered that the partial decomposition reaction of the electrolytic solution is in progress. It is considered that such a decomposition reaction produces a substance in which a part of the electrolytic solution is decomposed. It is considered that the substance in which a part of the electrolytic solution is decomposed in this way is further decomposed on the positive electrode to generate carbon dioxide gas and the like. Examples 1 to 66
Since the coating is also formed on the positive electrode, the above reaction is also suppressed.

As shown in Table 1, the same results as those described above were obtained with respect to the battery swelling after being left at 60 ° C. for a long period of time. Also, as for the capacity retention rate after long-term storage at 60 ° C., as shown in Table 1, the same tendency as the above result was obtained.

(Summary) From the above, the non-aqueous electrolyte is at least one selected from sultone compounds, cyclic sulfates and vinylene carbonate, and an alkylbenzene derivative having a tertiary carbon adjacent to a phenyl group, a cycloalkylbenzene derivative and a biphenyl derivative. It has been found that a non-aqueous secondary battery having excellent high temperature storage characteristics can be obtained by including at least one selected from the following.

<Other Embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are also included in the technical scope of the present invention. In addition to the above, various modifications can be made without departing from the scope of the invention.

In the above-described embodiment, the prismatic non-aqueous secondary battery 1 has been described, but the battery structure is not particularly limited, and needless to say, it may be a cylindrical, bag-shaped, lithium polymer battery or the like.

[0077]

According to the present invention, a non-aqueous secondary battery having excellent high temperature storage characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a prismatic non-aqueous secondary battery according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Non-aqueous secondary battery 2 ... Electrode group 3 ... Positive electrode 4 ... Negative electrode 5 ... Separator 6 ... Battery case 7 ... Battery lid 8 ... Safety valve 9 ... Negative electrode terminal 10 ... Positive electrode lead 11 ... Negative electrode lead

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Claims (6)

[Claims] 1. A non-aqueous secondary battery comprising a positive electrode, a negative electrode and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is adjacent to at least one selected from a sultone compound, a cyclic sulfuric acid ester and vinylene carbonate and a phenyl group. A non-aqueous secondary battery containing at least one selected from an alkylbenzene derivative having a tertiary carbon, a cycloalkylbenzene derivative, and a biphenyl derivative. 2. The non-aqueous secondary battery according to claim 1, wherein the sultone compound is any one of propane sultone, propene sultone and butane sultone. 3. The non-aqueous secondary battery according to claim 1 or 2, wherein the cyclic sulfate is one of glycol sulfate and propylene glycol sulfate. 4. The alkylbenzene derivative having a tertiary carbon adjacent to the phenyl group is cumene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, 1-methylpropylbenzene, 1,3-bis (1). −
The non-aqueous secondary battery according to any one of claims 1 to 3, which is either methylpropyl) benzene or 1,4-bis (1-methylpropyl) benzene. 5. The cycloalkylbenzene derivative,
It is any one of cyclohexylbenzene and cyclopentylbenzene.
The non-aqueous secondary battery according to any one of 1. 6. The biphenyl derivative is biphenyl,
2-fluorobiphenyl, 2-bromobiphenyl, 2-
The non-aqueous secondary battery according to any one of claims 1 to 5, which is any one of chlorobiphenyl.