JPWO2016076145A1 - Non-aqueous electrolyte secondary battery - Google Patents

Abstract

The present invention provides a non-aqueous electrolyte secondary battery that can suppress the capacity deterioration of the non-aqueous electrolyte secondary battery and maintain a stable battery capacity over a long period of time. A) A negative electrode containing a carbon material having a true specific gravity of 1.60-2.20 g / cm 3 as a negative electrode active material, (B) a positive electrode containing a positive electrode active material, and (C) a non-aqueous electrolysis in which a lithium salt is dissolved in an organic solvent. And (D) a non-aqueous electrolyte secondary battery comprising a separation membrane, (C) a compound represented by general formula (1) in a non-aqueous electrolyte obtained by dissolving a lithium salt in an organic solvent The compound represented by the general formula (2) is preferably further contained. General formulas (1) and (2) are as described in this specification.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery, and relates to a non-aqueous electrolyte secondary battery having a non-aqueous electrolyte containing a negative electrode active material containing a specific carbon material and a specific polyvalent carboxylic acid ester compound.

  With the spread of portable electronic devices such as portable personal computers, handy video cameras, and information terminals in recent years, non-aqueous electrolyte secondary batteries having high voltage and high energy density have been widely used as power sources. Also, from the viewpoint of environmental problems, battery cars and hybrid cars using electric power as a part of power have been put into practical use.

In recent years, from the viewpoint of further improving the performance of hybrid vehicles, further improvement in performance has been demanded for non-aqueous electrolyte secondary batteries, and there is an urgent need to improve the performance. Specifically, the discharge capacity is an important characteristic so that the current that is the energy source of the hybrid vehicle can be sufficiently supplied. In addition, in order to enable charging in a short time, the non-aqueous electrolyte secondary battery preferably maintains a high charge capacity up to a high current density and is also required to have a high charge capacity maintenance rate.
In addition, the hybrid vehicle needs to have long-term reliability, that is, less capacity deterioration after long-term use than the portable electronic device.
In order to provide a non-aqueous electrolyte secondary battery suitable for such a hybrid vehicle, artificial graphite that has been used as a negative electrode active material in portable electronic devices such as portable personal computers, handy video cameras, information terminals, etc. In addition, a highly crystalline carbon material such as natural graphite has a small distance between carbon layers, so that it is difficult to smoothly insert and desorb lithium ions, and a high charge capacity retention rate cannot be satisfied.
For this reason, attention has been focused on a low crystalline carbon material that can smoothly insert and desorb lithium ions.

  On the other hand, the non-aqueous electrolyte secondary battery has a negative electrode active material that is reductively decomposed on the surface of the negative electrode active material made of a carbon material regardless of whether it is a high crystalline carbon or a low crystalline carbon during the initial charge. A film called SEI (Solid Electrolyte Interface) is formed on the surface. This film has the effect of suppressing the decomposition of the electrolyte solution in the negative electrode, but if the stability of the film is low, there is a problem that the reductive decomposition of the electrolyte solution occurs due to repeated charge and discharge, which causes the battery capacity to deteriorate. .

For this reason, in the non-aqueous electrolyte secondary battery, various additives for the non-aqueous electrolyte have been proposed in order to improve the stability and electrical characteristics of the non-aqueous electrolyte secondary battery. Examples of such additives include 1,3-propane sultone (for example, see Patent Document 1), vinyl ethylene carbonate (for example, see Patent Document 2), vinylene carbonate (for example, see Patent Document 3), 1, 3-Propane sultone, butane sultone (for example, refer to Patent Document 4), vinylene carbonate (for example, refer to Patent Document 5), vinyl ethylene carbonate (for example, refer to Patent Document 6), and the like have been proposed. Carbonate is widely used because of its great effect. These additives are considered to form a stable film called SEI on the surface of the negative electrode, and this film covers the surface of the negative electrode, thereby suppressing the reductive decomposition of the electrolytic solution. In addition, silylbenzene-based additives (see, for example, Patent Document 8), polycarboxylic acid silyl ester-based additives (for example, see Patent Document 9), and the like are disclosed.
However, electrolyte additives that have been reported so far are electrolyte additives applied to highly crystalline carbon materials such as artificial graphite and natural graphite. It is not described in detail in the literature.
Carbon materials with high crystallinity such as graphite have a high potential on the surface of the negative electrode active material, so that they are highly reactive with electrolytes and additives and easily form SEI, whereas carbon materials with low crystallinity are negative electrode active materials Since the surface potential is low, the reactivity with the electrolysis solution is low. Therefore, it is difficult to form SEI that is stable and sufficiently covers the surface.
For this reason, until now, sufficient SEI could not be formed on the surface of the active material, and thus the storage characteristics could not be improved.

JP 63-102173 A JP-A-4-87156 Japanese Patent Laid-Open No. 5-74486 Japanese Patent Laid-Open No. 10-50342 US Pat. No. 5,626,981 US Pat. No. 6,919,145 US Patent Publication No. 2004/0043300 US Patent Publication No. 2004/0106039 US Patent Publication No. 2015/0044531

  Accordingly, an object of the present invention is to suppress capacity deterioration in a non-aqueous electrolyte secondary battery.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by using a non-aqueous electrolyte containing a negative electrode active material containing a specific carbon material and a polyvalent carboxylic acid ester compound having a specific structure. The headline and the present invention were completed.

The present invention provides (A) a negative electrode containing a carbon material having a true specific gravity of 1.60-2.20 g / cm ³ as a negative electrode active material, (B) a positive electrode containing a positive electrode active material, and (C) a lithium salt as an organic solvent. In a non-aqueous electrolyte secondary battery comprising a dissolved non-aqueous electrolyte and (D) a separation membrane,
(C) A nonaqueous electrolyte secondary battery comprising a compound represented by the following general formula (1) in a nonaqueous electrolyte obtained by dissolving a lithium salt in an organic solvent. .

（式中、Ｒ¹は２価の炭素原子数２〜６の不飽和炭化水素、炭素原子数６〜１２のアリーレン基又は２価の炭素原子数３〜１２の複素環含有基を表し、Ｒ²〜Ｒ⁷はそれぞれ独立して炭素原子数１〜６のアルキル基、炭素原子数２〜６のアルケニル基又は炭素原子数２〜６のアルキニル基を表す。）

(In the formula, R ¹ represents a divalent unsaturated hydrocarbon having 2 to 6 carbon atoms, an arylene group having 6 to 12 carbon atoms, or a divalent heterocyclic group having 3 to 12 carbon atoms; ^{2 to} R ⁷ each independently represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms.

（式中、Ｒ⁸〜Ｒ¹⁵はそれぞれ独立して水素原子、炭素原子数１〜６のアルキル基、炭素原子数１〜６のアルコキシ基、フェニル基、フェノキシ基、若しくはベンジル基、又は、フッ素、塩素、臭素若しくは炭素原子数１〜６のアルキル基で置換されたフェニル基、フェノキシ基、若しくはベンジル基を表わす。）In the present invention, the nonaqueous electrolytic solution (2) is characterized in that (C) a nonaqueous electrolytic solution obtained by dissolving a lithium salt in an organic solvent contains a compound represented by the following general formula (2). A secondary battery is provided.

(In the formula, R ^{8 to} R ¹⁵ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, a phenoxy group, a benzyl group, or fluorine. Represents a phenyl group, a phenoxy group, or a benzyl group substituted with chlorine, bromine, or an alkyl group having 1 to 6 carbon atoms.

  According to the present invention, suppression of capacity deterioration of a non-aqueous electrolyte secondary battery can be realized.

FIG. 1 is a longitudinal sectional view schematically showing an example of the structure of a coin-type battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 2 is a schematic diagram showing a basic configuration of a cylindrical battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 3 is a perspective view showing the internal structure of the cylindrical battery of the nonaqueous electrolyte secondary battery of the present invention as a cross section.

Hereinafter, the nonaqueous electrolyte secondary battery of the present invention will be described in detail based on preferred embodiments.
<(A) Negative Electrode Containing Carbon Material with True Specific Gravity 1.60-2.20 g / cm ³ as Negative Electrode Active Material>
The negative electrode active material for a non-aqueous electrolyte secondary battery of the present invention is a carbon material having a true specific gravity in the range of 1.60 to 2.20 g / cm ³ . The carbon material that gives such true specific gravity can be obtained by calcining coal-based and / or petroleum-based (coal-based, etc.) raw coke, or coal-based calcined coke, alone or mixed. (In this specification, the term “coal-based, etc.” may be “coal-based and / or petroleum-based”, that is, either coal-based or petroleum-based, or a mixture of both. Good thing.) When the true specific gravity is less than 1.60 g / cm ³ , when applied to a lithium ion secondary battery, a side reaction occurs during charge and discharge, leading to a decrease in capacity and efficiency. On the other hand, if the true specific gravity exceeds 2.20 g / cm ³ , the input / output characteristics and capacity retention characteristics are degraded when applied to a battery. Coal-based raw coke is petroleum-based and / or coal-based heavy oil, for example, using a coking facility such as a delayed coker, and the highest temperature is about 400 ° C. to 700 ° C. for about 24 hours. It means the one obtained by carrying out the decomposition and polycondensation reaction, and the coal-based calcined coke means the one obtained by calcining the coal-based raw coke and the maximum temperature reached 800 ° C. It means petroleum-based and / or coal-based coke calcined at about ˜2000 ° C.

  To describe in detail the method for obtaining a negative active material for a non-aqueous electrolyte secondary battery with a true specific gravity within the above range, first, use a heavy oil such as coal-based heavy oil using a coking facility such as a delayed coker. Coal-based coke is obtained by advancing the thermal decomposition / polycondensation reaction at a temperature of about 400 ° C. to 700 ° C. for about 24 hours. Thereafter, the obtained coal-based raw coke mass is pulverized to a predetermined size. An industrially used pulverizer can be used for the pulverization. Specific examples include atomizers, Raymond mills, impeller mills, ball mills, cutter mills, jet mills, hybridizers, orient mills, but are not particularly limited thereto. In the pulverization step, two or more of these apparatuses may be used for pulverization, or a single apparatus may be used for pulverization a plurality of times.

  The heavy coal oil used here may be a heavy petroleum oil or a heavy coal oil, but the heavy heavy oil is richer in aromatic properties, Since there are few impurities, such as S, V, and Fe, and there is also little volatile matter, it is more preferable to use a coal-type heavy oil.

  Moreover, the negative electrode active material for non-aqueous electrolyte secondary batteries used here is coal-based and / or petroleum-based (coal-based etc.) raw coke, or coal-based calcined coke alone or mixed. In the process, a plurality of baking processes and / or a shape control process such as granulation in the process, and / or a process of modifying and coating the surface with different organic and inorganic components And / or through a process of forming different metal components uniformly or dispersed on the surface.

  Further, the coal-based raw coke obtained as described above is calcined at a maximum temperature of 800 ° C. to 2000 ° C. to produce coal-based calcined coke. For firing raw coke such as coal-based, equipment such as reed hammer furnace, shuttle furnace, tunnel furnace, rotary kiln, roller hearth kiln or microwave capable of mass heat treatment can be used, but it is particularly limited to these. is not. Moreover, these baking facilities may be either a continuous type or a batch type. Next, the obtained coal-based calcined coke lump is pulverized to a predetermined size using a pulverizer such as an industrially used atomizer in the same manner as described above. The pulverized coke powder can be sized to a predetermined particle size by cutting fine powder by classification or removing coarse powder with a sieve or the like.

The firing temperature is preferably 800 ° C. or more and 2000 ° C. or less at the highest temperature reached. When the firing temperature exceeds the upper limit, crystal growth of the coke material is excessively promoted, and it becomes difficult to make the true specific gravity 2.20 g / cm ³ or less. If the true specific gravity exceeds 2.20 g / cm ³ , the crystal structure of the coke is oriented like graphite during firing, and the distance between crystal layers becomes narrow. As described above, the input / output characteristics, capacity retention ratio, etc. Therefore, the characteristic due to the structure will be deteriorated. When the firing temperature is lower than the lower limit, the crystal structure becomes undeveloped and the true specific gravity is not more than 1.60 g / cm ^3, and the functional group derived from the raw material (OH group, COOH group, etc.) is present on the coke surface. As described above, a side reaction occurs when the battery is charged and discharged as described above, leading to a decrease in capacity and efficiency.

The true specific gravity is measured by a liquid phase replacement method (also known as a pycnometer method). Specifically, the powder of the negative electrode active material is put into a pycnometer, a solvent liquid such as distilled water is added, and the air and the solvent liquid on the powder surface are replaced by a method such as vacuum degassing to obtain an accurate powder weight and volume. To calculate the true specific gravity value.
(Note that the true specific gravity in a carbon material is one of the indices indicating the degree of crystallinity (graphitization). Generally, a carbon material having a true specific gravity of 2.20 g / cm ³ or more is made of highly crystalline carbon, .23 g / cm ³ or more is called graphite.)

The negative electrode is obtained by mixing a negative electrode active material containing a carbon material having a true specific gravity of 1.60-2.20 g / cm ³ on a current collector (generally copper foil), a conductive material, and a binder. It consists of a composite material layer to be formed. True specific gravity is preferably 1.60-2.20g / cm ³ of the negative electrode active material, 2.05-2.20g / cm ³ is more preferred.

As the negative electrode active material for a non-aqueous electrolyte secondary battery, a carbon material having a true specific gravity in the range of 1.60 to 2.20 g / cm ³ by the above method may be used as it is. A carbon material having a specific gravity in the range of 1.60 to 2.20 g / cm ³ and a carbon material having a true specific gravity of 2.20 g / cm ³ or more may be mixed.
When the latter mixture is used, the mass ratio of the carbon material having a true specific gravity in the range of 1.60 to 2.20 g / cm ³ by the above method and the carbon material having a true specific gravity of 2.20 g / cm ³ or more is , Preferably 5 wt% or more, more preferably 10 wt% or more.
When the carbon material having a true specific gravity in the range of 1.60 to 2.20 g / cm ³ is less than 5 wt%, the capacity deterioration effect on the entire battery is reduced, and the effect of the present electrolyte solution additive cannot be sufficiently obtained.

  Generally, the binder (binder) is a water-soluble adhesive such as fluorine resin powder such as polyvinylidene fluoride (PVDF) or polyimide (PI) resin, styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC). Although an agent is used, it is not limited to these. The amount of the negative electrode binder used is preferably 0.01 to 20 parts by mass and more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material.

  Examples of the conductive material for the negative electrode include graphite fine particles, carbon black such as acetylene black and ketjen black, amorphous carbon fine particles such as needle coke, and carbon nanofibers, but are not limited thereto. 0.01-20 mass parts is preferable with respect to 100 mass parts of negative electrode active materials, and, as for the usage-amount of the electrically conductive material of a negative electrode, 0.1-10 mass parts is still more preferable.

Formation of the composite material layer on the current collector is performed by preparing a slurry of the negative electrode active material and the binder described above using a solvent, and applying and drying on the current collector (generally copper foil). It can be performed by pressing under any condition. The solvent used is not particularly limited, and N-methylpyrrolidone (NMP), dimethylformamide, water, alcohol, or the like is used.
The solvent for the negative electrode is preferably used in combination with a thickener when water is used as the solvent. The amount of the solvent is adjusted so that the viscosity of the paste can be easily applied to the current collector.
Examples of the current collector of the negative electrode include stainless steel foil, nickel foil, copper foil, nickel mesh, or copper mesh.

<(B) Positive Electrode Containing Positive Electrode Active Material>
As a positive electrode used in the present invention, as in a normal secondary battery, a positive electrode active material, a binder, a conductive material and the like slurryed with an organic solvent or water are applied to a current collector and dried. A sheet is used. The positive electrode active material contains a transition metal and lithium and is preferably a material containing one kind of transition metal and lithium. Examples thereof include a lithium transition metal composite oxide and a lithium-containing transition metal phosphate compound. These may be used in combination.
As the transition metal of the lithium transition metal composite oxide, vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper and the like are preferable.
Specific examples of the lithium transition metal composite oxide include lithium cobalt composite oxide such as LiCoO ₂ , lithium nickel composite oxide such as LiNiO ₂ , and lithium manganese composite oxide such as LiMnO ₂ , LiMn ₂ O ₄ , and Li ₂ MnO _3. Some of the transition metal atoms that are the main components of these lithium transition metal composite oxides are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium, etc. The thing substituted with the other metal etc. are mentioned.
Specific examples of the substituted ones include, for example, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.80 Co _0.17 Al _0.03 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O ₄ or the like.
As the transition metal of the lithium-containing transition metal phosphate compound, vanadium, titanium, manganese, iron, cobalt, nickel and the like are preferable. Specific examples thereof include iron phosphates such as LiFePO ₄ and phosphorus such as LiCoPO _4. Cobalt acids, some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium And those substituted with other metals such as niobium.

The binder for the positive electrode and the solvent for forming the slurry are the same as those used for the negative electrode. The amount of the binder used for the positive electrode is preferably 0.001 to 20 parts by mass, more preferably 0.01 to 10 parts by mass, and most preferably 0.02 to 8 parts by mass with respect to 100 parts by mass of the positive electrode active material. preferable. 30-300 mass parts is preferable with respect to 100 mass parts of positive electrode active materials, and, as for the usage-amount of the solvent of a positive electrode, 50-200 mass parts is still more preferable.
Examples of the conductive material for the positive electrode include graphite fine particles, carbon black such as acetylene black and ketjen black, amorphous carbon fine particles such as needle coke, and carbon nanofibers, but are not limited thereto.
0.01-20 mass parts is preferable with respect to 100 mass parts of positive electrode active materials, and, as for the usage-amount of the electrically conductive material of a positive electrode, 0.1-10 mass parts is still more preferable.
As the current collector for the positive electrode, aluminum, stainless steel, nickel-plated steel or the like is usually used.

（上記構造式中、Ｘ¹、Ｘ²、Ｘ³はそれぞれ独立に、酸素原子又は硫黄原子を表す。尚、式中の＊は、これらの式で表される基が、＊部分で、隣接する基と結合することを意味する。）
Ｒ¹としては、変質し難く耐久性の高い表面構造とすることができることから、ビニレン、エチニレン、１，４−フェニレン、チオフェン−２，５−イル（２，５−チオフェニレン）が好ましく、ビニレンが最も好ましい。<(C) Nonaqueous electrolytic solution in which lithium salt is dissolved in organic solvent>
A nonaqueous electrolytic solution in which a lithium salt used in the present invention is dissolved in an organic solvent (hereinafter also simply referred to as “nonaqueous electrolytic solution”) will be described. The nonaqueous electrolytic solution contains a compound represented by the general formula (1). Hereinafter, this compound will be described.
The divalent unsaturated hydrocarbon having 2 to 6 carbon atoms represented by R ¹ in the general formula (1) is particularly limited as long as it is a divalent hydrocarbon group containing an unsaturated double bond or triple bond in the group. Specific examples include vinylene, propenylene, isopropenylene, butenylene, pentenylene, hexenylene, 1-propenylene-2,3-diyl, ethynylene, propynylene, butynylene, pentynylene, hexynylene, and the like. Examples of the arylene group having 6 to 12 include 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, and the like. Examples of the divalent heterocyclic group having 3 to 12 carbon atoms include the following: The structure of this is mentioned.

(In the above structural formulas, X ¹ , X ² , and X ³ each independently represent an oxygen atom or a sulfur atom. In the formula, * represents a group represented by these formulas adjacent to the * moiety. It means to bond with the group to be.)
R ¹ is preferably vinylene, ethynylene, 1,4-phenylene, thiophen-2,5-yl (2,5-thiophenylene), and vinylene because it is difficult to change and can have a highly durable surface structure. Is most preferred.

Examples of the alkyl group having 1 to 6 carbon atoms represented by R ^{2 to} R ⁷ in the general formula (1) include methyl, ethyl, propyl, butyl, isobutyl, s-butyl, t-butyl, pentyl, isopentyl, cyclopentyl, and hexyl. Cyclohexyl, etc., and examples of the alkenyl group having 2 to 6 carbon atoms include vinyl, allyl, 3-butenyl, isobutenyl, 4-pentenyl, 5-hexenyl, etc., and an alkynyl group having 2 to 6 carbon atoms. Examples thereof include ethynyl, 2-propynyl, 2-butynyl, 3-butynyl and the like.
As R ^{2 to} R ⁷ , methyl, ethyl, propyl, butyl, and vinyl are preferable, and methyl is most preferable because a highly durable surface structure that hardly changes in quality can be obtained.

  Specific examples of the compound represented by the general formula (1) include bis (trimethylsilyl) acetylenedicarboxylate, bis (ethyldimethylsilyl) acetylenedicarboxylate, bis (dimethylpropylsilyl) acetylenedicarboxylate, bis (dimethyl Butylsilyl) acetylenedicarboxylate, bis (dimethylvinylsilyl) acetylenedicarboxylate, bis (trimethylsilyl) fumarate, bis (trimethylsilyl) maleate, bis (trimethylsilyl) phthalate, bis (trimethylsilyl) isophthalate, bis (terephthalate) (Trimethylsilyl), bis (trimethylsilyl) itaconate and the like.

In the non-aqueous electrolyte, the compound represented by the general formula (1) may be used alone or in combination of two or more.
Further, in the nonaqueous electrolytic solution of the present invention, when the content of the compound represented by the general formula (1) is too small, a sufficient effect cannot be exhibited, and when the content is too large, the compounding amount is met. The content of the compound represented by the general formula (1) is 0.001 in the non-aqueous electrolyte because not only the increase effect is obtained but also the characteristics of the non-aqueous electrolyte may be adversely affected. Is preferably 10 to 10% by mass, more preferably 0.01 to 8% by mass, and most preferably 0.03 to 5% by mass.

It is preferable that the nonaqueous electrolytic solution used in the present invention contains the compound represented by the general formula (2) because the effects of the present invention are remarkably exhibited. Hereinafter, the compound represented by the general formula (2) will be described.
As the alkyl group having 1 to 6 carbon atoms represented by R ^{8 to} R ¹⁵ in the general formula (2), the same groups as those exemplified as those represented by the alkyl group having 1 to 6 carbon atoms represented by R ² above. As the alkoxy group having 1 to 6 carbon atoms represented by R ^{8 to} R ¹⁵ , methoxy, ethoxy, propoxy, butoxy, isobutyloxy, s-butyloxy, t-butyloxy, pentoxy, isopentyloxy, cyclopentyloxy, Examples include hexyloxy and cyclohexyloxy.
Examples of the alkyl group having 1 to 6 carbon atoms for substituting the phenyl group, phenoxy group, and benzyl group include the alkyl groups having 1 to 6 carbon atoms listed above.
Among the groups represented by R ^{8 to} R ¹⁰ , those which are alkyl groups having 1 to 6 carbon atoms are preferable, and among the groups represented by R ^{11 to} R ¹⁵ , hydrogen atoms or alkyl groups having 1 to 6 carbon atoms are preferable. Some are preferred.

  Specific examples of the compound represented by the general formula (2) include trimethylphenylsilane, triethylphenylsilane, 1-trimethylsilyl-4-methylbenzene, ethoxy (methyl) diphenylsilane, monomethyltriphenylsilane and the like.

In the non-aqueous electrolyte, the compound represented by the general formula (2) may be used alone or in combination of two or more.
When the compound represented by the general formula (2) is used, the content of the compound represented by the general formula (2) is preferably 0.001 to 20% by mass in the nonaqueous electrolytic solution, 0.01 to 10 mass% is still more preferable and 0.1-5 mass% is the most preferable.

  The non-aqueous electrolytic solution used in the present invention further includes a fluorosilane compound containing two or more difluorosilyl groups in the molecule, a cyclic carbonate compound having an unsaturated group, a chain carbonate compound, an unsaturated diester compound, and a cyclic sulfate ester. An aromatic silane compound other than the compound represented by the general formula (2) can be added, a cyclic sulfite ester, a sultone, an unsaturated phosphate ester compound, a halogenated cyclic carbonate compound.

Examples of fluorosilane compounds containing two or more difluorosilyl groups in the molecule include bis (difluoromethylsilyl) methane, 1,2-bis (difluoromethylsilyl) ethane, and 1,3-bis (difluoromethylsilyl). Examples include propane, 1,4-bis (difluoromethylsilyl) butane, 1,4- (bisdifluoromethylsilyl) benzene, tris (difluoromethylsilyl) methane, tetrakis (difluoromethylsilyl) methane, and the like. Bis (difluoromethylsilyl) ethane, 1,3-bis (difluoromethylsilyl) propane, 1,4-bis (difluoromethylsilyl) butane, and tris (difluoromethylsilyl) methane are preferred,
Examples of the cyclic carbonate compound having an unsaturated group include vinylene carbonate, vinyl ethylene carbonate, propylidene carbonate, ethylene ethylidene carbonate, ethylene isopropylidene carbonate, and vinylene carbonate and vinyl ethylene carbonate are preferable.
Examples of the chain carbonate compound include dipropargyl carbonate, propargyl methyl carbonate, ethyl propargyl carbonate, bis (1-methylpropargyl) carbonate, and bis (1-dimethylpropargyl) carbonate.
Examples of the unsaturated diester compounds include dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dipentyl maleate, dihexyl maleate, diheptyl maleate, dioctyl maleate, dimethyl fumarate, diethyl fumarate, and fumaric acid. Dipropyl, dibutyl fumarate, dipentyl fumarate, dihexyl fumarate, diheptyl fumarate, dioctyl fumarate, dimethyl acetylenedicarboxylate, diethyl acetylenedicarboxylate, dipropyl acetylenedicarboxylate, dibutyl acetylenedicarboxylate, dipentyl acetylenedicarboxylate, acetylenedicarboxylic acid Dihexyl, diheptyl acetylenedicarboxylate, dioctyl acetylenedicarboxylate, etc.
Examples of the cyclic sulfate include 1,3,2-dioxathiolane-2,2-dioxide, 1,3-propanediol cyclic sulfate, propane-1,2-cyclic sulfate, and the like.
Examples of the cyclic sulfite ester include ethylene sulfite and propylene sulfite.
Examples of the sultone include propane sultone, butane sultone, 1,5,2,4-dioxadithiolane-2,2,4,4-tetraoxide and the like.
Examples of the unsaturated phosphate ester compound include tris (2-propynyl) phosphate, diphenyl-2-methacryloyloxyethyl phosphate, and the like. Examples of the halogenated cyclic carbonate compound include chloroethylene carbonate, dichloroethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, and the like.
As aromatic silane compounds other than the compound represented by the general formula (2), 1,1,2,2-tetramethyl-1,2-diphenyldisilane, 1,4-bis (trimethylsilyl) benzene, 1, Examples thereof include 2-bis (trimethylsilyl) benzene.
Among these additives, 1,2-bis (difluoromethylsilyl) ethane, 1,4-bis (difluoromethylsilyl) butane, tris (difluoromethylsilyl) methane, vinylene carbonate, vinylethylene carbonate, dipropargyl carbonate, Dimethyl acetylenedicarboxylate, diethyl acetylenedicarboxylate, propane sultone, butane sultone, tris (2-propynyl) phosphate, chloroethylene carbonate, dichloroethylene carbonate, and fluoroethylene carbonate are preferred, 1,2-bis (difluoromethylsilyl) ethane, 1,4-bis (difluoromethylsilyl) butane, tris (difluoromethylsilyl) methane, vinylene carbonate, dipropargyl carbonate, acetylene More preferred are dimethyl rubonate, propane sultone, and fluoroethylene carbonate, 1,2-bis (difluoromethylsilyl) ethane, 1,4-bis (difluoromethylsilyl) butane, tris (difluoromethylsilyl) methane, vinylene carbonate, And fluoroethylene carbonate is most preferred.

  These additives may be used alone or in combination of two or more. In the non-aqueous electrolyte, the content of these additives is usually 20% by mass or less in total in the non-aqueous electrolyte, preferably 5% by mass or less, and more preferably 3% by mass or less. .

  As an organic solvent used for the non-aqueous electrolyte, those usually used for the non-aqueous electrolyte can be used alone or in combination of two or more. Specifically, saturated cyclic carbonate compounds, saturated cyclic ester compounds, sulfoxide compounds, sulfone compounds, amide compounds, saturated chain carbonate compounds, chain ether compounds, cyclic ether compounds, saturated chain ester compounds, phosphorus-containing organic solvents, etc. Is mentioned.

Among the above organic solvents, saturated cyclic carbonate compounds, saturated cyclic ester compounds, sulfoxide compounds, sulfone compounds and amide compounds have a high relative dielectric constant, and thus serve to increase the dielectric constant of non-aqueous electrolytes. Compounds are preferred.
Examples of such saturated cyclic carbonate compounds include ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate, 1,2-butylene carbonate, 1,3-butylene carbonate, 1,1, -dimethylethylene carbonate. Etc.
Examples of the saturated cyclic ester compound include γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-hexanolactone, and δ-octanolactone.
Examples of the sulfoxide compound include dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide, diphenyl sulfoxide, thiophene, and the like.
Examples of the sulfone compounds include dimethyl sulfone, diethyl sulfone, dipropyl sulfone, diphenyl sulfone, sulfolane (also referred to as tetramethylene sulfone), 3-methyl sulfolane, 3,4-dimethyl sulfolane, 3,4-diphenimethyl sulfolane, sulfolene. , 3-methylsulfolene, 3-ethylsulfolene, 3-bromomethylsulfolene and the like, and sulfolane and tetramethylsulfolane are preferable.
Examples of the amide compound include N-methylpyrrolidone, dimethylformamide, dimethylacetamide and the like.
Among the above organic solvents, saturated chain carbonate compounds, chain ether compounds, cyclic ether compounds and saturated chain ester compounds can lower the viscosity of the non-aqueous electrolyte and increase the mobility of electrolyte ions. Battery characteristics such as output density can be made excellent. Moreover, since it is low-viscosity, the performance of the non-aqueous electrolyte at a low temperature can be enhanced, and among them, a saturated chain carbonate compound is preferable.
Examples of such saturated chain carbonate compounds include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethyl butyl carbonate, methyl-t-butyl carbonate, diisopropyl carbonate, and t-butyl propyl carbonate. Etc.
Examples of the chain ether compound or the cyclic ether compound include dimethoxyethane (DME), ethoxymethoxyethane, diethoxyethane, tetrahydrofuran, dioxolane, dioxane, 1,2-bis (methoxycarbonyloxy) ethane, 1,2 -Bis (ethoxycarbonyloxy) ethane, 1,2-bis (ethoxycarbonyloxy) propane, ethylene glycol bis (trifluoroethyl) ether, propylene glycol bis (trifluoroethyl) ether, ethylene glycol bis (trifluoromethyl) ether And diethylene glycol bis (trifluoroethyl) ether. Among these, dioxolane is preferred.
As the saturated chain ester compound, monoester compounds and diester compounds having a total of 2 to 8 carbon atoms in the molecule are preferable, and specific compounds include methyl formate, ethyl formate, methyl acetate, and ethyl acetate. , Propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, ethyl trimethyl acetate, methyl malonate, ethyl malonate, methyl succinate, ethyl succinate, 3 -Methyl methoxypropionate, ethyl 3-methoxypropionate, ethylene glycol diacetyl, propylene glycol diacetyl and the like, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, as well as Propionic acid ethyl are preferred.
Examples of the phosphorus-containing organic solvent include phosphoric acid esters such as trimethyl phosphate, triethyl phosphate, and triphenyl phosphate; phosphorous acid esters such as trimethyl phosphite and triethyl phosphite, and triphenyl phosphite. Phosphine oxides such as trimethylphosphine oxide, triethylphosphine oxide, triphenylphosphine oxide, and phosphazenes.

  In addition, acetonitrile, propionitrile, nitromethane, and derivatives thereof can also be used as the organic solvent.

As the lithium salt to be dissolved in the organic solvent, conventionally known lithium salts are used. For example, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiB (CF ₃ SO ₃ ) ₄ , LiB (C ₂ O ₄ ) ₂ , LiBF ₂ (C ₂ O ₄ ), LiSbF ₆ , LiSiF ₅ , LiAlF ₄ , LiSCN, LiClO ₄ , LiCl LiF, LiBr, LiI, LiAlF ₄ , LiAlCl ₄ , and derivatives thereof, among which LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , and LiC (CF ₃ SO ₂ ) ₃ and derivatives LiCF ₃ SO _3, and LiC (CF ₃ SO ₂₎ to use at least one member selected from the group consisting of ₃ derivatives The preferred because of excellent electrical characteristics.

  The lithium salt can be dissolved in the organic solvent so that the concentration in the non-aqueous electrolyte of the present invention is 0.1 to 3.0 mol / L, particularly 0.5 to 2.0 mol / L. preferable. If the concentration of the lithium salt is less than 0.1 mol / L, a sufficient current density may not be obtained, and if it is more than 3.0 mol / L, the stability of the nonaqueous electrolyte may be impaired. The lithium salt may be used in combination of two or more lithium salts.

In addition, halogen-based, phosphorus-based and other flame retardants can be appropriately added to the non-aqueous electrolyte in order to impart flame retardancy. If the amount of flame retardant added is too small, sufficient flame retarding effect cannot be exerted.If it is too large, not only an increase effect corresponding to the blending amount can be obtained, but on the other hand, the characteristics of the non-aqueous electrolyte Since it may have a bad influence, it is preferable that it is 1-50 mass% with respect to the organic solvent which comprises the non-aqueous electrolyte of this invention, and it is still more preferable that it is 3-10 mass%.
Specific examples of the halogen-based flame retardant include di (2,2,2-trifluoroethyl) carbonate, di (2,2,3,3-tetrafluoropropyl) carbonate, di (2,2,3,3, 4,4,5,5-octafluoropentyl) carbonate, 2,2,3,3,3-pentafluoropropyl-1,1,2,2-tetrafluoroethyl ether, etc. Specific examples include trimethyl phosphate and triethyl phosphate.

<(D) Separation membrane>
In the nonaqueous electrolyte secondary battery of the present invention, a separation membrane is used between the positive electrode and the negative electrode. As the separation membrane, a commonly used polymer microporous film can be used without particular limitation. Examples of the film include polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polytetrafluoroethylene, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, polyethylene oxide and polypropylene oxide. Films composed of ethers, various celluloses such as carboxymethylcellulose and hydroxypropylcellulose, polymer compounds mainly composed of poly (meth) acrylic acid and various esters thereof, derivatives thereof, copolymers and mixtures thereof. Etc. These films may be used alone, or may be used as a multilayer film by superimposing these films. Furthermore, various additives may be used for these films, and the kind and content thereof are not particularly limited. Among these films, a film made of polyethylene, polypropylene, polyvinylidene fluoride, or polysulfone is preferably used for the nonaqueous electrolyte secondary battery of the present invention.

  These films are microporous so that the electrolyte can penetrate and ions can easily pass therethrough. The microporosity method includes a phase separation method in which a polymer compound and a solvent solution are formed into a film while microphase separation is performed, and the solvent is extracted and removed to make it porous. The film is extruded and then heat treated, the crystals are arranged in one direction, and a “stretching method” or the like is performed by forming a gap between the crystals by stretching, and is appropriately selected depending on the film used.

  In the non-aqueous electrolyte secondary battery of the present invention, the positive electrode material, the non-aqueous electrolyte, and the separation membrane have a phenol-based antioxidant, a phosphorus-based antioxidant, and a thioether-based antioxidant for the purpose of improving safety. Agents, hindered amine compounds and the like may be added.

<Structure of non-aqueous electrolyte secondary battery>
The non-aqueous electrolyte secondary battery according to the present invention having the above-described configurations (A) to (D) is not particularly limited in shape, and may have various shapes such as a coin shape, a cylindrical shape, and a square shape. Can do. FIG. 1 shows an example of a coin-type battery of the nonaqueous electrolyte secondary battery of the present invention, and FIGS. 2 and 3 show examples of a cylindrical battery, respectively.

  In the coin-type non-aqueous electrolyte secondary battery 10 shown in FIG. 1, 1 includes a positive electrode, 1a includes a positive electrode current collector, and 2 includes a carbon material having a true specific gravity of 1.60-2.20 g / cm 3 as a negative electrode active material. Negative electrode, 2a is a negative electrode current collector, 3 is a non-aqueous electrolyte in which a lithium salt is dissolved in an organic solvent, 4 is a stainless steel positive electrode case, 5 is a stainless steel negative electrode case, 6 is a polypropylene gasket, 7 Is a polyethylene separation membrane.

  2 and 3, 11 is a negative electrode, 11 is a negative electrode, 12 is a negative current collector, 13 is a positive electrode, 14 is a positive current collector, and 15 is a main battery. Nonaqueous electrolyte of the invention, 16 is a separation membrane, 17 is a positive electrode terminal, 18 is a negative electrode terminal, 19 is a negative electrode plate, 20 is a negative electrode lead, 21 is a positive electrode plate, 22 is a positive electrode lead, 23 is a case, 24 is an insulating plate , 25 are gaskets, 26 is a safety valve, and 27 is a PTC element.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples. In the examples, “parts” and “%” are based on mass unless otherwise specified.

[Examples 1-7 and Comparative Examples 1-11] Production and Evaluation of Nonaqueous Electrolyte Secondary Batteries In Examples and Comparative Examples, nonaqueous electrolyte secondary batteries (lithium secondary batteries) are prepared as follows. It was made according to.

<Production of each configuration>
[Production of Negative Electrode (A1)]
94.5 parts by mass of a carbon material having a true specific gravity of 2.01 as an active material, 1.0 part by weight of acetylene black as a conductive material, 3.0 parts by mass of styrene butadiene rubber as a binder, 1.5 parts by mass of carboxymethyl cellulose as a thickener Parts were mixed and dispersed in 50 parts by mass of water to form a slurry. This slurry was applied to a copper negative electrode current collector, dried and press-molded. Then, this negative electrode was cut into a predetermined size to produce a disc-shaped negative electrode A1.

[Production of negative electrode (A2)]
94.5 parts by mass of a carbon material having a true specific gravity of 2.14 as an active material, 1.0 part by mass of acetylene black as a conductive material, 3.0 parts by mass of styrene butadiene rubber as a binder, 1.5 parts by mass of carboxymethyl cellulose as a thickener Parts were mixed and dispersed in 50 parts by mass of water to form a slurry. This slurry was applied to a copper negative electrode current collector, dried and press-molded. Thereafter, this negative electrode was cut into a predetermined size to produce a disc-shaped negative electrode A2.

[Production of Negative Electrode (A′1)]
96.0 parts by weight of artificial graphite having a true specific gravity of 2.23 as an active material, 1.0 part by weight of acetylene black as a conductive material, 1.5 parts by weight of styrene butadiene rubber as a binder, and 1.5 parts by weight of carboxymethyl cellulose as a thickener Parts were mixed and dispersed in 120 parts by mass of water to form a slurry. This slurry was applied to a copper negative electrode current collector, dried and press-molded. Then, this negative electrode was cut into a predetermined size to produce a disk-shaped negative electrode A′1.

[Production of negative electrode (A3)]
2. 47.5 parts by mass of natural graphite having a true specific gravity of 2.23 and 47.5 parts by mass of a carbon material having a true specific gravity of 2.14 (artificial graphite / carbon material = 5/5) as an active material, and styrene-butadiene rubber as a binder. 0 part by mass and 1.5 parts by mass of carboxymethyl cellulose as a thickener were mixed and dispersed in 50 parts by mass of water to form a slurry. This slurry was applied to a copper negative electrode current collector, dried and press-molded. Then, this negative electrode was cut into a predetermined size to produce a disc-shaped negative electrode (A3).

[Production of negative electrode (A4)]
76 parts by weight of natural graphite having a true specific gravity of 2.23 and 19 parts by weight of a carbon material having a true specific gravity of 2.14 (artificial graphite / carbon material = 8/2) as active materials, and 3.0 parts by weight of styrene butadiene rubber as a binder, As a thickener, 1.5 parts by mass of carboxymethylcellulose was mixed and dispersed in 50 parts by mass of water to form a slurry. This slurry was applied to a copper negative electrode current collector, dried and press-molded. Thereafter, the negative electrode was cut into a predetermined size to produce a disc-shaped negative electrode (A4).

[Production of positive electrode (B1)]
After mixing 88 parts by mass of LiNiMnCoO ₂ (NMC) as an active material, 5 parts by mass of acetylene black as a conductive material, and 7 parts by mass of polyvinylidene fluoride (PVDF) as a binder, dispersed in 50 parts by mass of N-methylpyrrolidone (NMP) To form a slurry. This slurry was applied to an aluminum current collector, dried and press-molded. Thereafter, the positive electrode was cut into a predetermined size to produce a disc-shaped positive electrode B1.

(Preparation of electrolyte solution)
LiPF ₆ was dissolved at a concentration of 1 mol / L in a mixed solvent consisting of 30% by volume of ethylene carbonate, 40% by volume of ethyl methyl carbonate, and 30% by volume of dimethyl carbonate to prepare an electrolyte solution A.

[Preparation of non-aqueous electrolyte (C)]
As an electrolytic solution additive, compounds represented by the above general formula (1) (compounds C1-1, C1-2, C1-3 shown below), compounds represented by the above general formula (2) (shown below) Compound C2-1) and the compound C′1 shown below were dissolved in the electrolyte solution at the ratio shown in [Table 1] to prepare a nonaqueous electrolyte solution (C). In addition, the number in () in [Table 1] represents the concentration (% by mass) in the non-aqueous electrolyte.

[Compound C1-1]
Bis (trimethylsilyl) fumarate
[Compound C1-2]
Bis (trimethylsilyl) itaconate
[Compound C1-3]
Thiophene-2,5-dicarboxylate bis (trimethylsilyl)
[Compound C2-1]
Phenyltrimethylsilane [Compound C′1]
Vinylene carbonate

[Assembling the battery]
The obtained disc-shaped negative electrode (A) and disc-shaped positive electrode (B) were held in a case with a polypropylene microporous film ((D) separation membrane) having a thickness of 25 μm. Then, each non-aqueous electrolyte was poured into the case so that the non-aqueous electrolyte (C) adjusted as shown in Table 1 and the case was sealed and sealed. The nonaqueous electrolyte secondary batteries (φ20 mm, coin type with a thickness of 3.2 mm) of Examples 1 to 14 were manufactured.

Using the nonaqueous electrolyte secondary batteries of Examples 1 to 13 and Comparative Examples 1 to 14, the capacity loss rate due to battery deterioration was evaluated by the following test method. The results are shown in Table 1.
After the preparation of the non-aqueous electrolyte secondary battery, 5 cycles of charging and discharging were performed at 25 ° C., and the discharge capacity for the fifth time was defined as “capacity before storage”. Then, it left still for 2 weeks in a 60 degreeC thermostat in a full charge state. After two weeks, the battery was charged and discharged at 25 ° C. for 5 cycles, and the discharge capacity for the fifth time (the 10th time after battery preparation) was defined as “capacity after storage”. As shown in the following formula, capacity loss due to battery deterioration was determined as a ratio when “capacity before storage” was 100.
Capacity loss rate (%) = [1-[(capacity after storage) / (capacity before storage)]] × 100

As is clear from the results of [Table 1] and [Table 2], (A) a non-aqueous electrolyte secondary using a negative electrode containing a carbon material having a true specific gravity of 1.60-2.20 g / cm ³ as a negative electrode active material In the battery, when the compound represented by the general formula (1) is added to the non-aqueous electrolyte, storage deterioration of the battery is suppressed, and when the compound represented by the general formula (2) is further added, Storage deterioration is remarkably suppressed.

  From the above, the nonaqueous electrolyte secondary battery of the present invention is useful because it can maintain a stable battery capacity over a long period of time.

DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Positive electrode collector 2 Negative electrode 2a Negative electrode collector 3 Electrolytic solution 4 Positive electrode case 5 Negative electrode case 6 Gasket 7 Separation membrane 10 Coin type nonaqueous electrolyte secondary battery 10 'Cylindrical type nonaqueous electrolyte secondary Battery 11 Negative electrode 12 Negative electrode current collector 13 Positive electrode 14 Positive electrode current collector 15 Electrolyte 16 Separation membrane 17 Positive electrode terminal 18 Negative electrode terminal 19 Negative electrode plate 20 Negative electrode lead 21 Positive electrode 22 Positive electrode lead 23 Case 24 Insulating plate 25 Gasket 26 Safety valve 27 PTC element

[0008]
A carbon material having a range of ˜2.20 g / cm ³ may be used as it is, and a carbon material having a true specific gravity in the range of 1.60 to 2.20 g / cm ³ by the above method and a true specific gravity of 2. A carbon material of 20 g / cm ³ or more may be mixed.
When the latter mixture is used, the mass ratio of the carbon material having a true specific gravity in the range of 1.60 to 2.20 g / cm ³ and the carbon material having a true specific gravity of 2.20 g / cm ³ or more by the above method is The carbon material having a true specific gravity in the range of 1.60 to 2.20 g / cm ³ is preferably 5 wt% or more, more preferably 10 wt% or more based on the mixture.
When the carbon material having a true specific gravity in the range of 1.60 to 2.20 g / cm ³ is less than 5 wt%, the capacity deterioration effect on the entire battery is reduced, and the effect of the present electrolyte solution additive cannot be sufficiently obtained.
[0023]
Generally, the binder (binder) is a water-soluble adhesive such as fluorine resin powder such as polyvinylidene fluoride (PVDF) or polyimide (PI) resin, styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC). Although an agent is used, it is not limited to these. The amount of the negative electrode binder used is preferably 0.01 to 20 parts by mass and more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material.
[0024]
Examples of the conductive material for the negative electrode include graphite fine particles, carbon black such as acetylene black and ketjen black, amorphous carbon fine particles such as needle coke, and carbon nanofibers, but are not limited thereto. 0.01-20 mass parts is preferable with respect to 100 mass parts of negative electrode active materials, and, as for the usage-amount of the electrically conductive material of a negative electrode, 0.1-10 mass parts is still more preferable.
[0025]
Formation of the composite material layer on the current collector is performed by preparing a slurry of the negative electrode active material and the binder described above using a solvent, and applying and drying on the current collector (generally copper foil). It can be performed by pressing under any condition. The solvent used is not particularly limited, and N-methylpyrrolidone (NMP), dimethylformamide, water, alcohol, or the like is used. The solvent for the negative electrode is preferably used in combination with a thickener when water is used as the solvent. The amount of solvent is such that the paste is easy to apply to the current collector.

Claims (2)

(A) As a negative electrode active material, a negative electrode containing a carbon material having a true specific gravity of 1.60-2.20 g / cm ³ , (B) a positive electrode containing a positive electrode active material, and (C) a lithium salt dissolved in an organic solvent. In a non-aqueous electrolyte secondary battery comprising a water electrolyte and (D) a separation membrane,
(C) A non-aqueous electrolyte secondary battery comprising a compound represented by the following general formula (1) in a non-aqueous electrolyte obtained by dissolving a lithium salt in an organic solvent.

(In the formula, R ¹ represents a divalent unsaturated hydrocarbon having 2 to 6 carbon atoms, an arylene group having 6 to 12 carbon atoms, or a divalent heterocyclic group having 3 to 12 carbon atoms; ^{2 to} R ⁷ each independently represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms. (C) The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte obtained by dissolving a lithium salt in an organic solvent contains a compound represented by the following general formula (2): .

(In the formula, R ^{8 to} R ¹⁵ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, a phenoxy group, a benzyl group, or fluorine. Represents a phenyl group, a phenoxy group, or a benzyl group substituted with chlorine, bromine, or an alkyl group having 1 to 6 carbon atoms.

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