JP6658079B2 - Non-aqueous electrolyte and non-aqueous electrolyte secondary battery using the same - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte secondary battery using the same.

With the rapid progress of portable electronic devices such as mobile phones and notebook personal computers, demands for higher capacity of batteries used for a main power supply and a backup power supply have been increased, and nickel-cadmium batteries and nickel-cadmium batteries have been required. A non-aqueous electrolyte secondary battery such as a lithium ion secondary battery having a higher energy density than a hydrogen battery has attracted attention.
As an electrolyte for a lithium ion secondary battery, an electrolyte such as LiPF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiCF ₃ (CF ₂ ) ₃ SO _{3 is used to} convert a high dielectric constant such as ethylene carbonate or propylene carbonate. A typical example is a non-aqueous electrolyte dissolved in a mixed solvent of a solvent and a low-viscosity solvent such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

  In addition, as a negative electrode active material of a lithium ion secondary battery, a carbonaceous material capable of inserting and extracting lithium ions is mainly used, and natural graphite, artificial graphite, amorphous carbon, and the like are typical examples. Can be Further, a metal or alloy-based negative electrode using silicon, tin, or the like for higher capacity is also known. As the positive electrode active material, a transition metal composite oxide capable of occluding and releasing lithium ions is mainly used, and typical examples of the transition metal include cobalt, nickel, manganese, and iron.

  In a non-aqueous electrolyte secondary battery using such a non-aqueous electrolyte, the reactivity differs depending on the composition of the non-aqueous electrolyte, so that the battery characteristics greatly change depending on the non-aqueous electrolyte. Various studies have been conducted on non-aqueous solvents and electrolytes to improve battery characteristics such as load characteristics, cycle characteristics, and storage characteristics of non-aqueous electrolyte secondary batteries, and to enhance battery safety during overcharge. It has been done.

Patent Literature 1 discloses that in a lithium battery including a positive electrode using lithium cobalt oxide as an active material, a negative electrode using carbon as an active material, a separator, and a nonaqueous electrolyte, a specific phosphorus compound is added to the electrolyte. Accordingly, studies have been made to improve the impregnation property of the electrolytic solution into the separator and to improve the battery characteristics.
Patent Literature 2 discloses a lithium battery including a positive electrode using lithium cobalt oxide as an active material, a negative electrode using carbon as an active material, and a non-aqueous electrolyte. Studies have been made to improve the swelling of the battery during high-temperature storage by adding a phosphorus compound having dissociable hydrogen and a compound having a sulfone structure.
Patent Literature 3 discloses a positive electrode using a lithium transition metal oxide represented by a lithium nickel manganese cobalt composite oxide as an active material, a composite negative electrode composed of SiO _x and graphite, and a lithium secondary composed of a non-aqueous electrolyte. In batteries, studies have been made to improve the cycle characteristics by adding vinylene carbonate and fluoroethylene carbonate to the electrolyte.
Patent Literature 4 discloses a positive electrode using a lithium transition metal oxide typified by a lithium nickel cobalt aluminum composite oxide as an active material, a composite negative electrode composed of Si, SiO _x and graphite, and a lithium composed of a nonaqueous electrolyte. In secondary batteries, studies have been made to improve the cycle characteristics by adding a phosphate ester having an unsaturated bond typified by triallyl phosphate to an electrolytic solution.

JP-A-2-244565 JP 2008-41635 A JP 2011-233245 A International Publication No. 2013/122146

  In recent years, the demand for improving the characteristics of lithium non-aqueous electrolyte secondary batteries is increasing, and it is necessary to combine all of the high-temperature storage characteristics, energy density, output characteristics, lifespan, and high-speed charge / discharge characteristics at a high level. Has been sought, but has not yet been achieved. There is a trade-off between durability performance, including high-temperature storage characteristics, and performance such as capacity and resistance, and conventional lithium non-aqueous electrolyte secondary batteries have a problem of poor overall performance balance. .

For example, Patent Documents 1 and 2 disclose the effect of using a phosphoric acid ester having a specific structure in an electrolytic solution and carbon as a negative electrode active material. However, metal particles and graphite particles that can be alloyed with Li are disclosed. No effect has been clarified on the effect of using a negative electrode active material containing
Patent Document 3 discloses that the use of an electrolyte containing vinylene carbonate and fluoroethylene carbonate improves the cycle characteristics of a battery when SiO _x and graphite are used as the negative electrode active material. However, in the first charge / discharge / aging process after battery assembly (hereinafter, also referred to as an initial conditioning process), there is much capacity loss in the process, and there is room for improvement in the battery manufacturing process.
Patent Document 4 discloses that the use of an electrolyte containing triallyl phosphate improves the cycle characteristics of a battery when Si, SiO _x and graphite are used as the negative electrode active material. However, there is room for improvement in the large current discharge characteristics.

  The present invention has been made in view of the above problems. That is, in the non-aqueous electrolyte battery, the non-aqueous electrolyte and the non-aqueous electrolyte have good balance of overall performance with respect to performance such as durability, capacity, resistance, and output characteristics, and can improve capacity loss at the time of initial conditioning. It is an object to provide an electrolyte battery.

  The inventors of the present invention have conducted intensive studies, and as a result, in a non-aqueous electrolyte battery including a negative electrode including a negative electrode active material containing metal particles and graphite particles that can be alloyed with Li, a specific compound is electrolyzed. It has been found that the above-mentioned problems can be solved by incorporating the compound in a liquid, and the present invention has been completed.

（式（Ａ）中、Ｒ_１〜Ｒ_３は、それぞれ独立して、炭素数１〜１０の炭化水素基を示し、ａ、ｂ、ｃは、それぞれ独立して、０〜５の整数を示し、かつａ＋ｂ＋ｃは１〜９の整数を示す。）
［２］前記一般式（Ａ）中、Ｒ_１〜Ｒ_３の内少なくとも１つが、メチル基であることを特徴とする、（ａ）に記載の非水系電解液。
［３］前記一般式（Ａ）中、Ｒ^１〜Ｒ^３がメチル基であり、ａ＝ｂ＝ｃ＝１又は２であることを特徴とする、［１］又は［２］に記載の非水系電解液。
［４］前記一般式（Ａ）で表される化合物を２種以上含有することを特徴とする、［１］乃至［３］のいずれかに記載の非水系電解液。
［５］前記一般式（Ａ）で表される化合物を２種以上含有している場合、Ｒ^１〜Ｒ^３の置換位置の比率が、オルト位、メタ位、パラ位の中でメタ位が最も多いことを特徴とする、［４］に記載の非水系電解液。
［６］前記一般式（Ａ）で表される化合物の含有量が、非水系電解液の全量に対して０．００１質量％以上１０質量％以下である、［１］乃至［５］のいずれかに記載の非水系電解液。
［７］更に炭素−炭素不飽和結合を有する環状カーボネート、フッ素原子を有する環状カーボネート、ニトリル化合物、環状スルホン酸エステル及び環状エーテル化合物からなる群より選ばれる少なくとも１種の化合物を含有することを特徴とする、［１］乃至［６］のいずれかに記載の非水系電解液。
［８］前記炭素−炭素不飽和結合を有する環状カーボネート、フッ素原子を有する環状カーボネート、ニトリル化合物、環状スルホン酸エステル及び環状エーテル化合物からなる群より選ばれる少なくとも１種の化合物の含有量が、非水系電解液の全量に対して０．００１質量％以上１０質量％以下である、［７］に記載の非水系電解液。
［９］前記Ｌｉと合金化可能な金属粒子が、Ｓｉ、Ｓｎ、Ａｓ、Ｓｂ、Ａｌ、Ｚｎ及びＷからなる群より選ばれる少なくとも１種の金属又はその金属化合物である、［１］乃至［８］のいずれかに記載の非水系電解液。
［１０］前記Ｌｉと合金化可能な金属粒子が、Ｓｉ又はＳｉ金属酸化物である、［１］乃至［９］のいずれかに記載の非水系電解液。
［１１］前記Ｌｉと合金化可能な金属粒子と黒鉛粒子とを含有する負極活物質が、金属及び／又は金属化合物と黒鉛粒子の複合体及び／又は混合体である、［１］乃至［１０］のいずれかに記載の非水系電解液。
［１２］前記Ｌｉと合金化可能な金属粒子と黒鉛粒子との合計に対する、前記Ｌｉと合金化可能な金属粒子の含有量が０．１〜２５質量％である、［１］乃至［１１］のいずれかに記載の非水系電解液。
［１３］前記Ｌｉと合金化可能な金属粒子と黒鉛粒子との合計に対する、前記Ｌｉと合金化可能な金属粒子の含有量が０．１〜２０質量％である、［１］乃至［１２］のいずれかに記載の非水系電解液。
［１４］前記Ｌｉと合金化可能な金属粒子と黒鉛粒子との合計に対する、前記Ｌｉと合金化可能な金属粒子の含有量が０．１〜１５質量％である、［１］乃至［１３］のいずれかに記載の非水系電解液。
［１５］前記Ｌｉと合金化可能な金属粒子と黒鉛粒子との合計に対する、前記Ｌｉと合金化可能な金属粒子の含有量が０．１〜１０質量％である、［１］乃至［１４］のいずれかに記載の非水系電解液。
［１６］金属イオンを吸蔵及び放出可能な正極と、金属イオンを吸蔵及び放出可能な、Ｌｉと合金化可能な金属粒子と黒鉛粒子とを含有する負極活物質を含む負極と、非水溶媒と該非水溶媒に溶解される電解質を含む非水系電解液とを備える非水系電解液二次電池に用いられる非水系電解液であって、［１］乃至［１５］のいずれかに記載の非水系電解液を含有することを特徴とする非水系電解液二次電池。 The gist of the present invention is as described below.
[1] a positive electrode capable of occluding and releasing metal ions;
A negative electrode containing a negative electrode active material containing metal particles and graphite particles capable of occluding and releasing metal ions and alloyable with Li,
A non-aqueous electrolyte used for a non-aqueous electrolyte secondary battery including a non-aqueous solvent and a non-aqueous electrolyte including an electrolyte dissolved in the non-aqueous solvent,
A non-aqueous electrolyte comprising a compound represented by the following general formula (A).

(In formula (A), R _{1 to} R ₃ each independently represent a hydrocarbon group having 1 to 10 carbon atoms, and a, b, and c each independently represent an integer of 0 to 5. And a + b + c represents an integer of 1 to 9.)
[2] The nonaqueous electrolyte according to (a), wherein in the general formula (A), at least one of R _{1 to} R ₃ is a methyl group.
[3] In the general formula (A), R ^{1 to} R ³ are a methyl group, and a = b = c = 1 or 2; Aqueous electrolyte.
[4] The non-aqueous electrolytic solution according to any one of [1] to [3], comprising two or more compounds represented by the general formula (A).
[5] When two or more compounds represented by the general formula (A) are contained, the ratio of substitution positions of R ^{1 to} R ³ is such that the meta position among the ortho, meta, and para positions is The non-aqueous electrolyte according to [4], characterized in that it is the most.
[6] Any of [1] to [5], wherein the content of the compound represented by the general formula (A) is 0.001% by mass or more and 10% by mass or less based on the total amount of the non-aqueous electrolyte. A non-aqueous electrolytic solution according to any one of the above.
[7] The composition further comprises at least one compound selected from the group consisting of a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom, a nitrile compound, a cyclic sulfonic acid ester, and a cyclic ether compound. The non-aqueous electrolyte according to any one of [1] to [6].
[8] The content of at least one compound selected from the group consisting of a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom, a nitrile compound, a cyclic sulfonate, and a cyclic ether compound is non-specific. The non-aqueous electrolyte according to [7], wherein the amount is 0.001% by mass or more and 10% by mass or less based on the total amount of the aqueous electrolyte.
[9] The metal particles capable of being alloyed with Li are at least one metal selected from the group consisting of Si, Sn, As, Sb, Al, Zn and W, or a metal compound thereof, [1] to [1]. 8] The non-aqueous electrolyte according to any one of [1] to [8].
[10] The non-aqueous electrolyte according to any one of [1] to [9], wherein the metal particles that can be alloyed with Li are Si or a Si metal oxide.
[11] The negative electrode active material containing metal particles and graphite particles that can be alloyed with Li is a composite and / or a mixture of a metal and / or a metal compound and graphite particles, [1] to [10]. ] The non-aqueous electrolyte according to any one of [1] to [10].
[12] The content of the metal particles that can be alloyed with Li is 0.1 to 25% by mass relative to the total of the metal particles and graphite particles that can be alloyed with Li, [1] to [11]. The non-aqueous electrolyte according to any one of the above.
[13] The content of the metal particles that can be alloyed with Li is 0.1 to 20% by mass relative to the total of the metal particles and the graphite particles that can be alloyed with Li, [1] to [12]. The non-aqueous electrolyte according to any one of the above.
[14] The content of the metal particles that can be alloyed with Li is 0.1 to 15% by mass based on the total of the metal particles and the graphite particles that can be alloyed with Li, [1] to [13]. The non-aqueous electrolyte according to any one of the above.
[15] The content of the metal particles that can be alloyed with Li is 0.1 to 10% by mass relative to the total of the metal particles and graphite particles that can be alloyed with Li, [1] to [14]. The non-aqueous electrolyte according to any one of the above.
[16] A positive electrode capable of occluding and releasing metal ions, a negative electrode including a negative electrode active material capable of occluding and releasing metal ions and containing metal particles and graphite particles capable of being alloyed with Li, and a non-aqueous solvent. A non-aqueous electrolyte used for a non-aqueous electrolyte secondary battery comprising: a non-aqueous electrolyte including an electrolyte dissolved in the non-aqueous solvent, wherein the non-aqueous electrolyte according to any one of [1] to [15]. A non-aqueous electrolyte secondary battery comprising an electrolyte.

According to the present invention, with respect to the lithium nonaqueous electrolyte secondary battery, durability and capacity, resistance, performance such as output characteristics are well balanced in overall performance, and capacity loss in the aging process at the time of initial conditioning is reduced. An improved and well-balanced battery can be provided.
Function / principle of the non-aqueous electrolyte secondary battery produced using the non-aqueous electrolyte of the present invention and the non-aqueous electrolyte secondary battery of the present invention being a secondary battery having a good overall performance balance Although it is not clear, it is considered as follows. However, the present invention is not limited to the operation and principle described below.

  Alloy-based active materials have attracted attention as next-generation negative electrodes because their theoretical capacity per weight / volume of the negative electrode active material is much larger than that of carbon negative electrodes currently used. However, the alloy-based active material has a very large volume change (100 to 300%) due to the occlusion and release of lithium ions. There is a problem such as deterioration of the substance. By repeating charge and discharge, the particles are pulverized to expose a new active surface (dangling bond). The reaction between the exposed surface and the electrolytic solution causes deterioration of the surface of the active material, resulting in a problem that the capacity of the active material itself is reduced, and the charge depth of the positive electrode and the negative electrode is shifted. In order to solve this problem, in the present invention, the compound represented by the formula (A) is contained in the non-aqueous electrolyte. Since the compound represented by the formula (A) is trifunctional and the starting point of the reaction is an alkyl group substituted with an aromatic ring, the compound reacts on the negative electrode to form a film that suitably suppresses the reaction of the electrolytic solution. It is considered that this suppresses the reaction between the negative electrode active material containing the metal particles and the graphite particles that can be alloyed with Li and the electrolyte, and particularly contributes to the suppression of the decomposition reaction of the electrolyte during the initial conditioning.

Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
Here, “wt%”, “ppm by weight” and “parts by weight” are synonymous with “mass%”, “ppm by mass” and “parts by mass”, respectively. When it is described, it means "weight ppm".

1. Non-aqueous electrolyte solution 1-1. Non-aqueous electrolytic solution of the present invention The non-aqueous electrolytic solution of the present invention is characterized by containing a compound represented by the following general formula (A).

1-1-1. Compound represented by general formula (A)

In the formula (A), R _{1 to} R ₃ each independently represent a hydrocarbon group having 1 to 10 carbon atoms, a, b, and c each independently represent an integer of 0 to 5, And a + b + c represents an integer of 1 to 9.

Specific examples of the hydrocarbon group having 1 to 10 carbon atoms include an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and an alkynyl group having 2 to 10 carbon atoms. Among them, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a straight-chain alkyl group having 1 to 4 carbon atoms Is mentioned. When the compound is the above-described hydrocarbon group, the compound represented by the general formula (A) reacts with a decomposition product of the electrolytic solution, and the resistance is prevented from being excessively increased.
Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group. Among them, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and a hexyl group are more preferable, and a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl are more preferable. And a hexyl group, particularly preferably a methyl group, an ethyl group, an n-propyl group and an n-butyl group. A methyl group and an ethyl group are most preferable because the increase in the viscosity of the electrolytic solution due to the inclusion of the compound is suppressed.
Specific examples of the alkenyl group include a vinyl group, an allyl group, a methallyl group, a 2-butenyl group, a 3-methyl-2-butenyl group, a 3-butenyl group, a 4-pentenyl group, and the like. Among them, a vinyl group, an allyl group, a methallyl group, and a 2-butenyl group are preferable, and a vinyl group, an allyl group, and a methallyl group are more preferable, and an allyl group is particularly preferable. This is because the alkenyl group described above has appropriate steric hindrance.
Specific examples of the alkynyl group include an ethynyl group, a 2-propynyl group, a 2-butynyl group, a 3-butynyl group, a 4-pentynyl group, and a 5-hexynyl group. Of these, preferred are an ethynyl group, a 2-propynyl group, a 2-butynyl group and a 3-butynyl group, more preferably a 2-propynyl group and a 3-butynyl group, and particularly preferably a 2-propynyl group. This is because the alkynyl group described above has appropriate steric hindrance.

From the viewpoint of the reactivity between the compound represented by the general formula (A) and the electrode, in the general formula (A), R _{1 to} R ₃ represent a hydrogen atom (that is, a, b, or c is 0); Or, it is preferably a methyl group. Among _them, more preferably one of R 1 to R ₃ is a methyl _group, and more preferably all R 1 to R ₃ is a methyl group.

  From the viewpoint of the reactivity between the compound represented by the general formula (A) and the electrode, in the general formula (A), each of a, b, and c is preferably independently 1 or 2. Above all, it is more preferable that a = b = c = 1 or 2, and it is further preferable that a = b = c = 1.

As the compound used in the present invention, a compound represented by the general formula (A) is used, and specific examples include a compound having the following structure.
In the following structural formulas, Et and Bu represent an ethyl group and an n-butyl group, respectively.

Preferably, a compound having the following structure is used. The resistance of the coating formed on the positive electrode can be suitably controlled.

More preferably, a compound having the following structure is exemplified. The compound has a suitable molecular size and can react efficiently on the positive electrode.

Particularly preferred are compounds having the following structures. This is because the side reaction suppression effect on the positive electrode is high.

Most preferably, a compound having the following structure is used. This is because the reaction with ○ proceeds favorably.

  The compounding amount of the compound represented by the general formula (A) with respect to the total amount of the nonaqueous electrolytic solution of the present invention is not limited, and is arbitrary as long as the effect of the present invention is not significantly impaired. In general, the content is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10.0% by mass or less, preferably 5.0% by mass or less. More preferably, it is blended with the electrolyte at a concentration of 4.0% by mass or less, more preferably 3.0% by mass or less. With the above concentration, the reactivity on the electrode and the reactivity of the electrolytic solution generated on the electrode with a base component such as a reduction product can be adjusted, and the battery characteristics can be optimized. The compound represented by the general formula (A) may be used alone, or two or more kinds may be used in combination, and it is preferable to use two or more kinds in combination.

  When two or more compounds represented by the general formula (A) are used in combination, the ratio of the meta-substituted compound is preferably large.

  When the above range is satisfied, the capacity loss due to aging during the initial conditioning and the characteristics of the initial gas and the like are further suppressed.

  The method for incorporating the compound represented by the general formula (A) into the electrolytic solution of the present invention is not particularly limited. In addition to the method of directly adding the compound to the electrolytic solution, a method of generating the compound in a battery or in the electrolytic solution may be mentioned. Examples of a method for generating the above compound include a method in which a compound other than these compounds is added, and a battery component such as an electrolyte is generated by oxidation, reduction, hydrolysis, or the like. Further, a method of producing a battery by applying an electrical load such as charge / discharge after producing the battery can also be mentioned.

  When the compound represented by the general formula (A) is contained in a non-aqueous electrolyte and is actually used for producing a non-aqueous electrolyte secondary battery, even if the battery is disassembled and the non-aqueous electrolyte is extracted again, In many cases, the content thereof is significantly reduced. Therefore, those in which the compound represented by the general formula (A) can be detected in a very small amount from the non-aqueous electrolyte extracted from the battery are considered to be included in the present invention. Further, when the compound represented by the general formula (A) is contained in a non-aqueous electrolyte solution and is actually used for producing a non-aqueous electrolyte secondary battery, the battery is disassembled and re-extracted into a non-aqueous electrolyte solution. Is detected on the positive electrode, negative electrode or separator, which is another component of the non-aqueous electrolyte secondary battery, even when the compound represented by the general formula (A) contains only a very small amount. Often. Therefore, when the compound represented by the general formula (A) is detected from the positive electrode, the negative electrode, and the separator, it can be assumed that the total amount is contained in the nonaqueous electrolyte. Under this assumption, the compound represented by the general formula (A) is preferably contained so as to fall within the above range.

1-2. At least one specific compound selected from the group consisting of cyclic carbonate having a carbon-carbon unsaturated bond, cyclic carbonate having a fluorine atom, nitrile compound, cyclic sulfonic acid ester, and cyclic ether compound Together with a compound represented by the general formula (A), a cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter sometimes referred to as an “unsaturated cyclic carbonate”), a cyclic carbonate having a fluorine atom, a nitrile compound, a cyclic compound It is preferable to use a sulfonic acid ester and a cyclic ether compound in combination.

1-2-1. Cyclic carbonate having a carbon-carbon unsaturated bond The cyclic carbonate having a carbon-carbon unsaturated bond is not particularly limited as long as it is a cyclic carbonate having a carbon-carbon double bond or a carbon-carbon triple bond. Any unsaturated carbonate can be used as the unsaturated cyclic carbonate. Note that a cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate. The unsaturated cyclic carbonate may have a fluorine atom (also referred to as a fluorinated unsaturated carbonate), in which case the fluorine atom is usually 6 or less, preferably 4 or less, and 1 or 2 Most preferably.

  Examples of the unsaturated cyclic carbonate include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, Catechol carbonates and the like.

As the vinylene carbonates,
Vinylene carbonate, methyl vinylene carbonate, 4,5-dimethylvinylene carbonate, phenylvinylene carbonate, 4,5-diphenylvinylene carbonate, vinylvinylene carbonate, 4,5-divinylvinylene carbonate, allylvinylenecarbonate, 4,5-diallylvinylenecarbonate , 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate and the like. .

Specific examples of the ethylene carbonate substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond include:
Vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5 -Ethynylethylene carbonate, 4-vinyl-5-ethynylethylene carbonate, 4-allyl-5-ethynylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl -5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-fluoro-4-vinylethylene -Carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-5-vinylethylene carbonate, 4,4-difluoro- 5-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5- Diallyl ethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene car Sulfonates, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate.

Among the above, preferred unsaturated cyclic carbonates include:
Vinylene carbonate, methylvinylene carbonate, 4,5-dimethylvinylene carbonate, vinylvinylene carbonate, 4,5-vinylvinylenecarbonate, allylvinylenecarbonate, 4,5-diallylvinylenecarbonate, vinylethylene carbonate, 4,5-divinylethylenecarbonate , 4-methyl-5-vinylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5 -Diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4-vinyl-5-ethynylethylene carbonate, 4-fluorovinyleneca Carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene Carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-5-vinylethylene carbonate, 4,4-difluoro-5-allylethylene carbonate, 4,5- Difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro- , 5-divinyl ethylene carbonate, and 4,5-difluoro-4,5-diallyl carbonate.

Vinylene carbonate, vinyl ethylene carbonate and ethynyl ethylene carbonate are particularly preferable because they form a particularly stable interfacial protective film.

  The molecular weight of the unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 80 or more and 250 or less. Within this range, the solubility of the unsaturated cyclic carbonate in the non-aqueous electrolytic solution can be easily ensured, and the effect of the present invention can be sufficiently exhibited. The molecular weight of the unsaturated cyclic carbonate is more preferably 85 or more, and even more preferably 150 or less.

  The method for producing the unsaturated cyclic carbonate described above is not particularly limited, and it is possible to arbitrarily select and produce a known method.

  As the unsaturated cyclic carbonate in the nonaqueous electrolyte solution of the present invention, one kind may be used alone, or two or more kinds may be used in optional combination and ratio. The amount of the unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The compounding amount is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.5% by mass or more in 100% by mass of the nonaqueous electrolyte. It is particularly preferably at least 1% by mass, and usually at most 10% by mass, preferably at most 5% by mass, more preferably at most 3% by mass. Within this range, the non-aqueous electrolyte secondary battery can easily exhibit a sufficient effect of improving the cycle characteristics, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity retention ratio is reduced. It is easy to avoid the situation.

1-2-2. Cyclic carbonate having a fluorine atom Examples of the specific compound having a fluorine atom include a fluorinated cyclic carbonate having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof. Examples thereof include fluorinated ethylene carbonate and derivatives thereof. Examples of the derivative of the fluorinated ethylene carbonate include a fluorinated ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). As the cyclic carbonate having a fluorine atom, ethylene carbonate having 1 to 8 fluorine atoms and a derivative thereof are preferable. In addition, about the cyclic carbonate which has a fluorine atom and has an unsaturated bond, said 1-2-1. It is described in.

As specific examples of them,
Monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methyl Ethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4- (fluoro Methyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene Boneto, 4,4-difluoro-5,5-dimethylethylene carbonate.

  Among these, at least one selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate gives high ionic conductivity and suitably forms an interface protective film. Is more preferable.

  As the cyclic carbonate having a fluorine atom, one kind may be used alone, or two or more kinds may be used in optional combination and ratio.

  The compounding amount of the cyclic carbonate having a fluorine atom with respect to the entire nonaqueous electrolyte of the present invention is not limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The compounding amount is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.5% by mass or more in 100% by mass of the nonaqueous electrolyte. It is particularly preferably at least 1% by mass, and usually at most 10% by mass, preferably at most 7% by mass, more preferably at most 5% by mass, still more preferably at most 3% by mass. However, monofluoroethylene carbonate may be used as a solvent, and in that case, the content is not limited to the above.

1-2-3. Nitrile Compound The type of the specific nitrile compound is not particularly limited as long as it has a cyano group in the molecule.

Specific examples of the nitrile compound include, for example,
Acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, decannitrile, lauronitrile, 2-methylbutyronitrile, trimethylacetonitrile, hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, acrylonitrile Methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, 2-hexene Nitrile, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile Nitrile groups such as 2,3,3-difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile and pentafluoropropionitrile A compound having one;
Malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, azeranitrile, sebaconitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, t-butyl 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2,3,3-trimethylsuccinonitrile, 2,2,3,3-tetramethylsuccinonitrile, 2,3-diethyl- 2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, bicyclohexyl-1,1-dicarbonitrile, bicyclohexyl-2,2-dicarbonitrile, bicyclohexyl-3 , 3 Dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2-diisobutyl-3,3-dimethylsuccinonitrile, 2 -Methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2,2,4,4-tetramethylglutaryl Nitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, maleonitrile, fumaronitrile, 1,4-dicyanopentane, 2,6-dicyanoheptane, 2, 7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobe Then, 1,4-dicyanobenzene, 3,3 '-(ethylenedioxy) dipropionitrile, 3,3'-(ethylenedithio) dipropionitrile, 3,9-bis (2-cyanoethyl) -2,4 Compounds having two nitrile groups, such as, 8,10-tetraoxaspiro [5,5] undecane, 3,3'-oxydipropionitrile, and 3,3'-thiodipropionitrile;
Cyclohexanetricarbonitrile, triscyanoethylamine, triscyanoethoxypropane, tricyanoethylene, pentanetricarbonitrile, 1,3,5-pentanetricarbonitrile, propanetricarbonitrile, 1,2,3-propanetricarbonitrile, Compounds having three cyano groups such as heptanetricarbonitrile and the like can be mentioned.

  Of these, valeronitrile, decannitrile, lauronitrile, crotononitrile, succinonitrile, glutaronitrile, adiponitrile, pimenitrile, suberonitrile, azeranitrile, sebaconitrile, undecandinitrile, dodecandinitrile, fumaronitrile, fumaronitrile (2-Cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane is preferred from the viewpoint of improving the storage characteristics of the non-aqueous electrolyte. In addition, valeronitrile, decannitrile, lauronitrile, crotononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [ Nitrile compounds such as [5,5] undecane are particularly preferred.

  As the nitrile compound, one kind may be used alone, and two kinds or more may be used in optional combination and ratio. The amount of the nitrile compound to be added to the entire nonaqueous electrolytic solution of the present invention is not limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The amount is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less in 100% by mass of the nonaqueous electrolyte. , Preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and most preferably 1% by mass or less. When the above range is satisfied, effects such as output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, and high-temperature storage characteristics of the nonaqueous electrolyte secondary battery are further improved.

1-2-4. Cyclic sulfonic acid ester The type of the cyclic sulfonic acid ester as the specific compound is not particularly limited.

Specific examples of the cyclic sulfonic acid ester include, for example,
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone , 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene -1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2-propene-1,3-sultone, 2 -Fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 2-methyl-1-prope -1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3 -Methyl-2-propene-1,3-sultone, 1,4-butanesultone, 1-fluoro-1,4-butanesultone, 2-fluoro-1,4-butanesultone, 3-fluoro-1,4-butanesultone, 4 -Fluoro-1,4-butane sultone, 1-methyl-1,4-butane sultone, 2-methyl-1,4-butane sultone, 3-methyl-1,4-butane sultone, 4-methyl-1,4-butane sultone, 1 -Butene-1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro- -Butene-1,4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4-sultone, 1-fluoro-2-butene-1,4-sultone , 2-fluoro-2-butene-1,4-sultone, 3-fluoro-2-butene-1,4-sultone, 4-fluoro-2-butene-1,4-sultone, 1-fluoro-3-butene -1,4-sultone, 2-fluoro-3-butene-1,4-sultone, 3-fluoro-3-butene-1,4-sultone, 4-fluoro-3-butene-1,4-sultone, 1 -Methyl-1-butene-1,4-sultone, 2-methyl-1-butene-1,4-sultone, 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1 , 4-sultone, 1-methyl-2-butene-1,4 -Sultone, 2-methyl-2-butene-1,4-sultone, 3-methyl-2-butene-1,4-sultone, 4-methyl-2-butene-1,4-sultone, 1-methyl-3 -Butene-1,4-sultone, 2-methyl-3-butene-1,4-sultone, 3-methyl-3-butene-1,4-sultone, 4-methyl-3-butene-1,4-sultone , 1,5-pentane sultone, 1-fluoro-1,5-pentane sultone, 2-fluoro-1,5-pentane sultone, 3-fluoro-1,5-pentane sultone, 4-fluoro-1,5-pentane Sultone, 5-fluoro-1,5-pentane sultone, 1-methyl-1,5-pentane sultone, 2-methyl-1,5-pentane sultone, 3-methyl-1,5-pentane sultone, 4-methyl- 1,5- Pentane sultone, 5-methyl-1,5-pentane sultone, 1-pentene-1,5-sultone, 2-pentene-1,5-sultone, 3-pentene-1,5-sultone, 4-pentene-1,5 -Sultone, 1-fluoro-1-pentene-1,5-sultone, 2-fluoro-1-pentene-1,5-sultone, 3-fluoro-1-pentene-1,5-sultone, 4-fluoro-1 -Pentene-1,5-sultone, 5-fluoro-1-pentene-1,5-sultone, 1-fluoro-2-pentene-1,5-sultone, 2-fluoro-2-pentene-1,5-sultone , 3-fluoro-2-pentene-1,5-sultone, 4-fluoro-2-pentene-1,5-sultone, 5-fluoro-2-pentene-1,5-sultone, 1-fluoro-3-pen 1,5-sultone, 2-fluoro-3-pentene-1,5-sultone, 3-fluoro-3-pentene-1,5-sultone, 4-fluoro-3-pentene-1,5-sultone, 5-fluoro-3-pentene-1,5-sultone, 1-fluoro-4-pentene-1,5-sultone, 2-fluoro-4-pentene-1,5-sultone, 3-fluoro-4-pentene- 1,5-sultone, 4-fluoro-4-pentene-1,5-sultone, 5-fluoro-4-pentene-1,5-sultone, 1-methyl-1-pentene-1,5-sultone, 2- Methyl-1-pentene-1,5-sultone, 3-methyl-1-pentene-1,5-sultone, 4-methyl-1-pentene-1,5-sultone, 5-methyl-1-pentene-1, 5-sultone, 1-methyl -2-pentene-1,5-sultone, 2-methyl-2-pentene-1,5-sultone, 3-methyl-2-pentene-1,5-sultone, 4-methyl-2-pentene-1,5 -Sultone, 5-methyl-2-pentene-1,5-sultone, 1-methyl-3-pentene-1,5-sultone, 2-methyl-3-pentene-1,5-sultone, 3-methyl-3 -Pentene-1,5-sultone, 4-methyl-3-pentene-1,5-sultone, 5-methyl-3-pentene-1,5-sultone, 1-methyl-4-pentene-1,5-sultone , 2-methyl-4-pentene-1,5-sultone, 3-methyl-4-pentene-1,5-sultone, 4-methyl-4-pentene-1,5-sultone, 5-methyl-4-pentene Sultone compounds such as -1,5-sultone ;
Sulfate compounds such as methylene sulfate, ethylene sulfate, propylene sulfate;
Disulfonate compounds such as methylene methane disulfonate and ethylene methane disulfonate;
1,2,3-oxathiazolidine-2,2-dioxide, 3-methyl-1,2,3-oxathiazolidine-2,2-dioxide, 3H-1,2,3-oxathiazole-2,2-dioxide 5,5H-1,2,3-oxathiazol-2,2-dioxide, 1,2,4-oxathiazolidine-2,2-dioxide, 4-methyl-1,2,4-oxathiazolidine-2,2- Dioxide, 3H-1,2,4-oxathiazole-2,2-dioxide, 5H-1,2,4-oxathiazole-2,2-dioxide, 1,2,5-oxathiazolidine-2,2-dioxide , 5-Methyl-1,2,5-oxathiazolidine-2,2-dioxide, 3H-1,2,5-oxathiazole-2,2-dioxide, 5H-1,2,5-oxathiazole-2 2-dioxide, 1,2,3-oxathiazinane-2,2-dioxide, 3-methyl-1,2,3-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,3-oxathiazine- 2,2-dioxide, 1,2,4-oxathiazinan-2,2-dioxide, 4-methyl-1,2,4-oxathiazinan-2,2-dioxide, 5,6-dihydro-1,2,4- Oxathiazine-2,2-dioxide, 3,6-dihydro-1,2,4-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,4-oxathiazine-2,2-dioxide, 1, 2,5-oxathiazinan-2,2-dioxide, 5-methyl-1,2,5-oxathiazinan-2,2-dioxide, 5,6-dihydro-1,2,5-oxathiazine-2 2-dioxide, 3,6-dihydro-1,2,5-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,5-oxathiazine-2,2-dioxide, 1,2,6- Oxathiazinane-2,2-dioxide, 6-methyl-1,2,6-oxathiazinan-2,2-dioxide, 5,6-dihydro-1,2,6-oxathiazine-2,2-dioxide, 3,4- Nitrogen-containing compounds such as dihydro-1,2,6-oxathiazine-2,2-dioxide and 5,6-dihydro-1,2,6-oxathiazine-2,2-dioxide;
1,2,3-oxathiafoslan-2,2-dioxide, 3-methyl-1,2,3-oxathiafoslan-2,2-dioxide, 3-methyl-1,2,3-oxathi Afoslan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiafoslan-2,2,3-trioxide, 1,2,4-oxathiafoslan-2,2-dioxide , 4-methyl-1,2,4-oxathiafoslan-2,2-dioxide, 4-methyl-1,2,4-oxathiafoslan-2,2,4-trioxide, 4-methoxy-1 , 2,4-oxathiafoslan-2,2,4-trioxide, 1,2,5-oxathiafoslan-2,2-dioxide, 5-methyl-1,2,5-oxathiafoslan- 2,2-dioxide, 5-methyl-1,2,5-oxathia Sulane-2,2,5-trioxide, 5-methoxy-1,2,5-oxathiafoslan-2,2,5-trioxide, 1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan-2,2,3-trioxide, 3-methoxy-1, 2,3-oxathiaphosphinan-2,2,3-trioxide, 1,2,4-oxathiaphosphinan-2,2-dioxide, 4-methyl-1,2,4-oxathiaphosphinan-2 , 2-dioxide, 4-methyl-1,2,4-oxathiaphosphinan-2,2,3-trioxide, 4-methyl-1,5,2,4-dioxathiaphosphinan-2,4- Dioxide, 4-methoxy 1,5,2,4-dioxathiaphosphinan-2,4-dioxide, 3-methoxy-1,2,4-oxathiaphosphinan-2,2,3-trioxide, 1,2,5-oxa Thiaphosphinan-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosphinan-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosphinan-2,2 3-trioxide, 5-methoxy-1,2,5-oxathiaphosphinan-2,2,3-trioxide, 1,2,6-oxathiaphosphinan-2,2-dioxide, 6-methyl-1, 2,6-oxathiaphosphinan-2,2-dioxide, 6-methyl-1,2,6-oxathiaphosphinan-2,2,3-trioxide, 6-methoxy-1,2,6-oxathia Phosphinan-2,2 Phosphorus-containing compounds such as, 3-trioxide;
Is mentioned.

Of these, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-propene-1, 3-sultone, 1-fluoro-1-propene-1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1,4- Butane sultone, methylene methane disulfonate, ethylene methane disulfonate are preferred from the viewpoint of improving the storage characteristics of the non-aqueous electrolyte,
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone and 1-propene-1,3-sultone More preferred.

  As the cyclic sulfonic acid ester, one kind may be used alone, and two kinds or more may be used in optional combination and ratio. The amount of the cyclic sulfonic acid ester relative to the entire nonaqueous electrolytic solution of the present invention is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The amount is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less in 100% by mass of the nonaqueous electrolyte. , Preferably 5% by mass or less, more preferably 3% by mass or less, particularly preferably 2% by mass or less, most preferably 1% by mass or less. When the above range is satisfied, effects such as output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, and high-temperature storage characteristics of the nonaqueous electrolyte secondary battery are further improved.

1-2-5. Cyclic ether compound Specific examples of the cyclic ether compound include a cyclic ether compound which is an aliphatic compound having an oxygen atom in a molecule and a cyclic ether compound which is an aromatic compound having an oxygen atom in a molecule. A cyclic ether compound which is an aliphatic compound having an oxygen atom in the molecule is preferable because the oxidation potential is appropriate and the amount of side reaction at room temperature can be reduced.

Specific examples of the cyclic ether compound include the following.
Ethylene oxide, propylene oxide, butylene oxide, styrene oxide, oxetane, 2-methyloxetane, 3-methyloxetane, tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 3-methyltetrahydrofuran, 3-ethyltetrahydrofuran, 2,2-dimethyl Tetrahydrofuran, 2,3-dimethyltetrahydrofuran, 2-vinyltetrahydrofuran, 3-vinyltetrahydrofuran, 2-ethynyltetrahydrofuran, 3-ethynyltetrahydrofuran, 2-phenyltetrahydrofuran, 3-phenyltetrahydrofuran, tetrahydropyran, 2-methyltetrahydropyran, 2- Ethyl tetrahydropyran, 3-methyltetrahydropyran, 3-ethyltetrahydropyran , 4-methyltetrahydropyran, 4-ethyltetrahydropyran, 2,2-dimethyltetrahydropyran, 2,3-dimethyltetrahydropyran, 2,4-dimethyltetrahydropyran, 3,3-dimethyltetrahydropyran, 3,4-dimethyl Tetrahydropyran, 4,4-dimethyltetrahydropyran, 2-vinyltetrahydropyran, 3-vinyltetrahydropyran, 4-vinyltetrahydropyran, 2-ethynyltetrahydropyran, 3-ethynyltetrahydropyran, 4-ethynyltetrahydropyran, 2-phenyl Tetrahydropyran, 3-phenyltetrahydropyran, 4-phenyltetrahydropyran, hexamethylene oxide, 2-methylhexamethylene oxide, 3-methylhexamethylene oxide, Samethylene oxide, 2-vinylhexamethylene oxide, 3-ethynylhexamethylene oxide, 4-phenylhexamethylene oxide, heptamethylene oxide, 2-methylheptamethylene oxide, 3-methylheptamethylene oxide, 4-ethylheptamethylene oxide, Octamethylene oxide, nonamethylene oxide, decamethylene oxide, 1,3-dioxolan, 2-methoxy-1,3-dioxolan, 2-methyl-1,3-dioxolan, 2,2-dimethyl-1,3-dioxolan, 4-methyl-1,3-dioxolan, 2-ethoxy-1,3-dioxolan, 2-ethyl-1,3-dioxolan, 2,2-diethyl-1,3-dioxolan, 4-ethyl-1,3- Dioxolan, 2,2,4-trimethyl-1,3-dio Oxolan, 2,2,4-triethyl-1,3-dioxolan, 1,3-dioxane, 4-methyl-1,3-dioxane, 2,4-dimethyl-1,3-dioxane, 2,2,4- Trimethyl-1,3-dioxane, 4-ethyl-1,3-dioxane, 2,4-diethyl-1,3-dioxane, 2,2,4-triethyl-1,3-dioxane, 4-phenyl-1, 3-dioxane, 3-methyl-1,3-dioxane, 5,5-dimethyl-1,3-dioxane, 2,5,5-trimethyl-1,3-dioxane, 4,6-dimethyl-1,3- Dioxane, 2,5-dimethyl-1,3-dioxane, 1,4-dioxane.

Among them, propylene oxide, butylene oxide, styrene oxide, oxetane, tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 3-methyltetrahydrofuran, 3-ethyltetrahydrofuran, 2,2-dimethyltetrahydrofuran, tetrahydropyran, 2-methyl Tetrahydropyran, 2-ethyltetrahydropyran, 3-methyltetrahydropyran, 3-ethyltetrahydropyran, 4-methyltetrahydropyran, 4-ethyltetrahydropyran, 2,2-dimethyltetrahydropyran, hexamethylene oxide, 1,3-dioxane , 4-methyl-1,3-dioxane is preferred,
Propylene oxide, styrene oxide, oxetane, tetrahydrofuran, 2-methyltetrahydrofuran, 2-ethyltetrahydrofuran, 2,2-dimethyltetrahydrofuran, tetrahydropyran, 2-methyltetrahydropyran, 2-ethyltetrahydropyran, 2,2-dimethyltetrahydropyran, Hexamethylene oxide, 1,3-dioxane, 4-methyl-1,3-dioxane are more preferred,
Oxetane, tetrahydrofuran, tetrahydropyran, hexamethylene oxide, 1,3-dioxane, 4-methyl-1,3-dioxane are particularly preferred,
Tetrahydrofuran, tetrahydropyran, 1,3-dioxane is more preferred,
Tetrahydropyran is most preferred.
When the compounds mentioned in the preferred examples are used, the effect of suppressing gas generation is particularly large.

  As the cyclic ether compound, one type may be used alone, or two or more types may be used in optional combination and ratio. The amount of the cyclic ether compound to be added to the entire nonaqueous electrolytic solution of the present invention is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The amount is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less in 100% by mass of the nonaqueous electrolyte. , Preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1.5% by mass or less, and most preferably 1.0% by mass or less. By using the above content, the gas generation suppressing effect can be sufficiently exhibited, and an unnecessary increase in resistance can be suppressed.

1-3. Electrolyte <Lithium salt>
As the electrolyte in the non-aqueous electrolyte of the present invention, a lithium salt is usually used. The lithium salt is not particularly limited as long as it is known to be used for this purpose, and any one can be used, and specific examples thereof include the following.

For _{example, LiPF 6, LiBF 4, LiClO} 4, LiAlF 4, LiSbF 6, inorganic lithium salts LiTaF 6, LiWF ₇ and the like;
Lithium tungstates such as LiWOF ₅ ;
HCO ₂ Li, CH ₃ CO ₂ Li, CH ₂ FCO ₂ Li, CHF ₂ CO ₂ Li, CF ₃ CO ₂ Li, CF ₃ CH ₂ CO ₂ Li, CF- ₃ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF Lithium carboxylate such as ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ CF ₂ CO ₂ Li;
FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ FSO ₃ Li, CHF ₂ SO ₃ Li, CF ₃ SO ₃ Li, CF ₃ CF ₂ SO ₃ Li, CF ₃ CF ₂ CF ₂ SO ₃ Li, CF ₃ CF ₂ Lithium sulfonate salts such as CF ₂ CF ₂ SO ₃ Li;

_{LiN (FCO) 2, LiN (} FCO) (FSO 2), LiN (FSO 2) 2, LiN (FSO 2) (CF 3 SO 2), LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO ₂ ) ₂ , Lithium imide salts such as lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ) ;
Lithium methide salts such as LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , and LiC (C ₂ F ₅ SO ₂ ) ₃ ;
Lithium oxalatoborate salts such as lithium difluorooxalatoborate and lithium bis (oxalato) borate;
Lithium oxalatophosphate salts such as lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate;
In addition, LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , LiBF ₃ C _{2 F 5, LiBF 3 C 3} F 7, LiBF 2 (CF 3) 2, LiBF 2 (C 2 F 5) 2, LiBF 2 (CF 3 SO 2) 2, LiBF 2 (C 2 F 5 SO 2) 2 And the like, and fluorine-containing organic lithium salts.

Among them, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiTaF ₆ , FSO ₃ Li, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) _{2, LiN (C 2 F 5} SO 2) 2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic _{1,3-perfluoropropanedisulfonylimide, LiC (FSO 2) 3,} LiC (CF 3 SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium difluorobisoxalatophosphate, LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) _{3 and the} like are particularly preferable because they have an effect of improving output characteristics, high-rate charge / discharge characteristics, high-temperature storage characteristics, cycle characteristics, and the like.

These lithium salts may be used alone or in combination of two or more. A preferable example in the case of using two or more kinds is a combination of LiPF ₆ and LiBF ₄ , LiPF ₆ and LiN (FSO ₂ ) ₂ , or a combination of LiPF ₆ and FSO ₃ Li, and the effect of improving load characteristics and cycle characteristics. There is.
In this case, the mixing amount of LiBF ₄ or FSO ₃ Li with respect to 100% by mass of the whole non-aqueous electrolyte is not limited, and is arbitrary as long as the effect of the present invention is not significantly impaired. Usually, it is 0.01% by mass or more, preferably 0.1% by mass or more, and usually 30% by mass or less, preferably 20% by mass or less.

Another example is the combined use of an inorganic lithium salt and an organic lithium salt, and the combined use of both has an effect of suppressing deterioration due to high-temperature storage. As the organic lithium salt, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic _{1,3-perfluoropropanedisulfonylimide, LiC (FSO 2) 3,} LiC (CF 3 SO 2) 3, LiC (C 2 F 5 SO ₂ ) ₃ , lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium difluorobisoxalatophosphate, LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) _{3 and the} like. In this case, the ratio of the organic lithium salt to 100% by mass of the whole nonaqueous electrolyte is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and preferably 30% by mass or less. And particularly preferably 20% by mass or less.

The concentration of these lithium salts in the non-aqueous electrolytic solution is not particularly limited as long as the effects of the present invention are not impaired, but the electric conductivity of the electrolytic solution is in a good range, and good battery performance is secured. In view of the above, the total molar concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, further preferably 0.5 mol / L or more, , Preferably 3 mol / L or less, more preferably 2.5 mol / L or less, and still more preferably 2.0 mol / L or less.
When the total molar concentration of the lithium salt is within the above range, the electric conductivity of the electrolytic solution becomes sufficient, and a decrease in electric conductivity due to an increase in viscosity and a decrease in battery performance due to the decrease are prevented.

1-4. Non-aqueous solvent The non-aqueous solvent in the present invention is not particularly limited, and a known organic solvent can be used. Examples thereof include a cyclic carbonate having no fluorine atom, a chain carbonate, a cyclic carboxylate, an ether-based compound, and a sulfone-based compound.

<Cyclic carbonate without fluorine atom>
Examples of the cyclic carbonate having no fluorine atom include a cyclic carbonate having an alkylene group having 2 to 4 carbon atoms.
Specific examples of the cyclic carbonate having no fluorine atom and having an alkylene group having 2 to 4 carbon atoms include ethylene carbonate, propylene carbonate, and butylene carbonate. Among them, ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics derived from the improvement of the degree of dissociation of lithium ions.

As the cyclic carbonate having no fluorine atom, one kind may be used alone, and two kinds or more may be used in optional combination and ratio.
The amount of the cyclic carbonate having no fluorine atom is not particularly limited, and is arbitrary as long as the effect of the present invention is not significantly impaired. However, when one type is used alone, the amount of the nonaqueous solvent is 100% by volume. Medium, it is at least 5% by volume, more preferably at least 10% by volume. By setting the content in this range, it is possible to avoid a decrease in electric conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte, and to improve the large current discharge characteristics, stability to the negative electrode, and cycle characteristics of the non-aqueous electrolyte secondary battery. Range. Further, the content is 95% by volume or less, more preferably 90% by volume or less, further preferably 85% by volume or less. By setting the content in this range, the viscosity of the non-aqueous electrolyte is set to an appropriate range, the decrease in ionic conductivity is suppressed, and the load characteristics of the non-aqueous electrolyte secondary battery are easily set to a favorable range.

<Chain carbonate>
As the chain carbonate, a chain carbonate having 3 to 7 carbon atoms is preferable, and a dialkyl carbonate having 3 to 7 carbon atoms is more preferable.
Specific examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, n-butyl methyl carbonate, and isobutyl methyl. Examples thereof include carbonate, t-butylmethyl carbonate, ethyl-n-propyl carbonate, n-butylethyl carbonate, isobutylethyl carbonate, and t-butylethyl carbonate.

Among them, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are particularly preferable. is there.
Further, chain carbonates having a fluorine atom (hereinafter sometimes referred to as “fluorinated chain carbonate”) can also be suitably used.

The number of fluorine atoms in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, they may be bonded to the same carbon or to different carbons.
Examples of the fluorinated chain carbonate include fluorinated dimethyl carbonate and its derivatives, fluorinated ethyl methyl carbonate and its derivatives, and fluorinated diethyl carbonate and its derivatives.

Examples of the fluorinated dimethyl carbonate and derivatives thereof include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, bis (difluoromethyl) carbonate, bis (trifluoromethyl) carbonate and the like. Can be
Examples of fluorinated ethyl methyl carbonate and derivatives thereof include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2 -Trifluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, ethyl trifluoromethyl carbonate and the like.

  Examples of the fluorinated diethyl carbonate and its derivatives include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, and ethyl- (2,2,2- Trifluoroethyl) carbonate, 2,2-difluoroethyl-2′-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2′-fluoroethyl carbonate, 2, 2,2-trifluoroethyl-2 ′, 2′-difluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate and the like can be mentioned.

One type of chain carbonate may be used alone, or two or more types may be used in combination at any combination and in any ratio.
The mixing amount of the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more in 100% by volume of the nonaqueous solvent. By setting the lower limit in this manner, the viscosity of the non-aqueous electrolyte is set to an appropriate range, the decrease in ionic conductivity is suppressed, and the large current discharge characteristics of the non-aqueous electrolyte secondary battery are easily set to a favorable range. Become. The chain carbonate content is preferably 90% by volume or less, more preferably 85% by volume or less, particularly preferably 80% by volume or less in 100% by volume of the nonaqueous solvent. By setting the upper limit in this manner, it is possible to avoid a decrease in electric conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte, and to easily set a large current discharge characteristic of the non-aqueous electrolyte secondary battery to a favorable range. .

<Cyclic carboxylate>
As the cyclic carboxylic acid ester, those having 3 to 12 carbon atoms are preferable.
Specifically, gamma-butyrolactone, gamma-valerolactone, gamma-caprolactone, epsilon-caprolactone and the like can be mentioned. Among them, gamma-butyrolactone is particularly preferable from the viewpoint of improving battery characteristics derived from the improvement of the degree of dissociation of lithium ions.

As the cyclic carboxylic acid ester, one type may be used alone, or two or more types may be used in optional combination and ratio.
The amount of the cyclic carboxylate is usually 5% by volume or more, more preferably 10% by volume or more in 100% by volume of the nonaqueous solvent. Within this range, the electric conductivity of the non-aqueous electrolyte can be improved, and the large-current discharge characteristics of the non-aqueous electrolyte secondary battery can be easily improved. The amount of the cyclic carboxylic acid ester is preferably 50% by volume or less, more preferably 40% by volume or less. By setting the upper limit in this manner, the viscosity of the non-aqueous electrolyte is adjusted to an appropriate range, a decrease in electric conductivity is avoided, an increase in negative electrode resistance is suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery is performed. The characteristics can be easily set in a good range.

<Ether compounds>
As the ether compound, a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms which may be partially substituted with fluorine are preferable.
As a chain ether having 3 to 10 carbon atoms,
Diethyl ether, di (2-fluoroethyl) ether, di (2,2-difluoroethyl) ether, di (2,2,2-trifluoroethyl) ether, ethyl (2-fluoroethyl) ether, ethyl (2 2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2-trifluoroethyl) ether, (2-fluoroethyl ) (1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, ethyl-n-propylether, ethyl (3-fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3-tetra) Fluoro-n-propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propyl ether, (2-fluoroethyl) (3-fluoro- n-propyl) ether, (2-fluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) Ether, (2-fluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, 2,2,2-trifluoroethyl-n-propylether, (2,2,2- (Trifluoroethyl) (3-fluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2 , 2-trifluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3,3-pentafluoro- n-propyl) ether, 1,1,2,2-tetrafluoroethyl-n-propyl ether, (1,1,2,2-tetrafluoroethyl) (3-fluoro-n-propyl) ether, (1, 1,2,2-tetrafluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3-tetrafluoro -N-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-propylether, (n- Propyl) (3-fluoro (N-propyl) ether, (n-propyl) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2,3,3-tetrafluoro-n-propyl) Ether, (n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3-fluoro-n-propyl) ether, (3-fluoro-n-propyl) (3 , 3,3-trifluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3,3,3-trifluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) ) (2,2,3,3- Trafluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (2,2,3 , 3-tetrafluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di ( 2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, methoxy (2-fluoroethoxy) methane, methoxy (2,2,2-tri Fluoroethoxy) methane, methoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoroethoxy) methane, ethoxy (2, , 2-trifluoroethoxy) methane, ethoxy (1,1,2,2-tetrafluoroethoxy) methane, di (2-fluoroethoxy) methane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) ) Methane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methane, di (2,2,2-trifluoroethoxy) methane, (2,2,2-trifluoroethoxy) ( 1,1,2,2-tetrafluoroethoxy) methane, di (1,1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, methoxyethoxyethane, methoxy (2-fluoroethoxy) ethane, methoxy (2, 2,2-trifluoroethoxy) ethane, methoxy (1,1,2,2-tetrafluoroethoxy) ethane, diethoxyethane, ethoxy Ethoxy (2-fluoroethoxy) ethane, ethoxy (2,2,2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, di (2-fluoroethoxy) ethane, (2 -Fluoroethoxy) (2,2,2-trifluoroethoxy) ethane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (2,2,2-trifluoroethoxy) Ethane, (2,2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n- Propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether and the like.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, , 4-dioxane and the like, and fluorinated compounds thereof.
Among the above ether compounds, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether have a high solvating ability to lithium ions. And dimethoxymethane, diethoxymethane, and ethoxymethoxymethane, which have low viscosity and provide high ionic conductivity.

One of the ether compounds may be used alone, or two or more thereof may be used in any combination and in any ratio.
The compounding amount of the ether compound is usually 5% by volume or more, preferably 10% by volume or more, more preferably 15% by volume or more, and preferably 70% by volume or less in 100% by volume of the non-aqueous solvent. It is more preferably at most 60% by volume, still more preferably at most 50% by volume.

  Within this range, it is easy to improve the lithium ion dissociation degree of the ether compound and to improve the ion conductivity derived from the decrease in viscosity, and when the negative electrode active material contains a carbonaceous material, the ether compound is lithium ion It is easy to avoid a situation where the capacity is reduced due to co-insertion with the above.

<Sulfone compound>
As the sulfone compound, a cyclic sulfone having 3 to 6 carbon atoms and a chain sulfone having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably one or two.

As the cyclic sulfone having 3 to 6 carbon atoms,
Trimethylene sulfones, tetramethylene sulfones, hexamethylene sulfones, which are monosulfone compounds;
Examples of the disulfone compound include trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones.

Among them, from the viewpoints of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferred, and tetramethylene sulfones (sulfolanes) are particularly preferred.
As the sulfolane, sulfolane and / or a sulfolane derivative (hereinafter sometimes referred to as “sulfolane” including sulfolane) is preferable. As the sulfolane derivative, one in which one or more hydrogen atoms bonded to carbon atoms constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group is preferable.

  Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methyl Sulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoro Methylsulfolane, 2- Trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3- (trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane , 5-fluoro-3- (trifluoromethyl) sulfolane and the like are preferable in that they have high ionic conductivity and high input / output characteristics.

Further, as a chain sulfone having 2 to 6 carbon atoms,
Dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, n-butyl methyl sulfone, n-butyl ethyl Sulfone, t-butyl methyl sulfone, t-butyl ethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoro Ethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, perfume Oroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di (trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, trifluoromethyl- n-propylsulfone, fluoromethylisopropylsulfone, difluoromethylisopropylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethylisopropylsulfone, pentafluoroethyl-n-propylsulfone, pentafluoroethylisopropylsulfone , Trifluoroethyl-n-butylsulfone, trifluoroethyl-t-butylsulfone, pentafluoroethyl- - butyl sulfone, pentafluoroethyl -t- butyl sulfone, and the like.

  Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone , Monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoro Ethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl isopropyl sulfone, tri Ruoroechiru -n- butyl sulfone, trifluoroethyl -t- butyl sulfone, trifluoromethyl -n- butyl sulfone, trifluoromethyl -t- butyl sulfone is high ion conductivity, preferable because the input-output characteristic is high.

One of the sulfone compounds may be used alone, or two or more thereof may be used in any combination and in any ratio.
The compounding amount of the sulfone compound is usually preferably at least 0.3% by volume, more preferably at least 1% by volume, still more preferably at least 5% by volume, and preferably at least 40% by volume, in 100% by volume of the nonaqueous solvent. % By volume or less, more preferably 35% by volume or less, further preferably 30% by volume or less.
Within this range, the effect of improving the durability such as cycle characteristics and storage characteristics can be easily obtained, and the viscosity of the non-aqueous electrolyte can be adjusted to an appropriate range to prevent a decrease in electric conductivity. When charging / discharging the aqueous electrolyte secondary battery at a high current density, it is easy to avoid a situation in which the charge / discharge capacity retention rate decreases.

<When a cyclic carbonate having a fluorine atom is used as a non-aqueous solvent>
The cyclic carbonate having a fluorine atom can be used in a non-aqueous electrolyte to form 1-2-2. As shown in the above, the compound can be used as an auxiliary in combination with the compound represented by the general formula (A), and can also be used as a non-aqueous solvent.
In the present invention, when using a cyclic carbonate having a fluorine atom as the non-aqueous solvent, as the non-aqueous solvent other than the cyclic carbonate having a fluorine atom, one of the non-aqueous solvents exemplified above, a cyclic carbonate having a fluorine atom They may be used in combination, or two or more kinds may be used in combination with a cyclic carbonate having a fluorine atom.

  For example, one of the preferable combinations of the non-aqueous solvent includes a combination mainly composed of a cyclic carbonate having a fluorine atom and a chain carbonate. Among them, the sum of the cyclic carbonate having a fluorine atom and the chain carbonate occupying the nonaqueous solvent is preferably 60% by volume or more, more preferably 80% by volume or more, further preferably 90% by volume or more, and the fluorine atom Is 3 vol% or more, preferably 5 vol% or more, more preferably 10 vol% or more, and still more preferably 15 vol% or more, with respect to the total of the cyclic carbonate having the above and the chain carbonate. It is usually at most 60% by volume, preferably at most 50% by volume, more preferably at most 40% by volume, further preferably at most 35% by volume, particularly preferably at most 30% by volume, most preferably at most 20% by volume.

When a combination of these non-aqueous solvents is used, the balance between the cycle characteristics and the high-temperature storage characteristics (particularly, the remaining capacity and high-load discharge capacity after high-temperature storage) of a battery manufactured using the combination may be improved.
For example, as a specific example of a preferred combination of a cyclic carbonate having a fluorine atom and a chain carbonate,
Monofluoroethylene carbonate and dimethyl carbonate, monofluoroethylene carbonate and diethyl carbonate, monofluoroethylene carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and dimethyl carbonate and diethyl carbonate, monofluoroethylene carbonate and dimethyl carbonate and ethyl methyl carbonate, monofluoro Examples include ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate, and monofluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

  Among the combination of a cyclic carbonate having a fluorine atom and a chain carbonate, those containing a symmetric chain alkyl carbonate as the chain carbonate are more preferable, and particularly, monofluoroethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, Those containing monofluoroethylene carbonate such as fluoroethylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, symmetric linear carbonates and asymmetric linear carbonates have cycle characteristics. And a large current discharge characteristic are preferable. Among them, the symmetric chain carbonates are preferably dimethyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.

  A preferable combination is a combination of the combination of the cyclic carbonate having a fluorine atom and the chain carbonates further added with a cyclic carbonate having no fluorine atom. Among them, the sum of the cyclic carbonate having a fluorine atom and the cyclic carbonate having no fluorine atom in the nonaqueous solvent is preferably 10% by volume or more, more preferably 15% by volume or more, and still more preferably 20% by volume or more. And the proportion of the cyclic carbonate having a fluorine atom to the total of the cyclic carbonate having a fluorine atom and the cyclic carbonate having no fluorine atom is 1% by volume or more, preferably 3% by volume or more, more preferably 5% by volume or more. It is more preferably at least 10% by volume, particularly preferably at least 20% by volume, preferably at most 95% by volume, more preferably at most 85% by volume, further preferably at most 75% by volume, particularly preferably at most 60% by volume. These are:

When a cyclic carbonate having no fluorine atom is contained in this concentration range, the electric conductivity of the electrolytic solution can be maintained while forming a stable protective film on the negative electrode.
Specific examples of a preferred combination of a cyclic carbonate having a fluorine atom, a cyclic carbonate having no fluorine atom and a chain carbonate,
Monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, diethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, monofluoro Ethylene carbonate, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate G, monofluoroethylene carbonate and propylene carbonate and dimethyl carbonate, monofluoroethylene carbonate and propylene carbonate and diethyl carbonate, monofluoroethylene carbonate and propylene carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and propylene carbonate and dimethyl carbonate and diethyl carbonate; Monofluoroethylene carbonate, propylene carbonate, dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and propylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and propylene carbonate, dimethyl carbonate and diethyl carbonate Tyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, monofluoroethylene Carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate and Examples include diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

Among combinations of a cyclic carbonate having a fluorine atom and a cyclic carbonate having no fluorine atom and a chain carbonate, those containing an asymmetric chain alkyl carbonate as the chain carbonate are more preferable, particularly,
Monofluoroethylene carbonate and ethylene carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and propylene carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and ethylene carbonate and dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and propylene carbonate and dimethyl carbonate Ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and propylene carbonate Ethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and ethylene carbonate and propylene carbonate and diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and ethylene carbonate and dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and propylene carbonate And dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Since the balance of Le characteristics and large-current discharge characteristics may preferably. Among them, the asymmetric chain carbonates are preferably ethyl methyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.

When ethyl methyl carbonate is contained in the non-aqueous solvent, the proportion of ethyl methyl carbonate in the total non-aqueous solvent is preferably 10% by volume or more, more preferably 20% by volume or more, and still more preferably 25% by volume or more. It is particularly preferably at least 30% by volume, more preferably at most 95% by volume, more preferably at most 90% by volume, further preferably at most 85% by volume, particularly preferably at most 80% by volume. In some cases, the load characteristics of the battery may be improved.
In the combination mainly composed of a cyclic carbonate having a fluorine atom and a chain carbonate, in addition to the cyclic carbonate having no fluorine atom, a cyclic carboxylate, a chain carboxylate, a cyclic ether, a chain Other solvents such as ethers, sulfur-containing organic solvents, phosphorus-containing organic solvents, and fluorine-containing aromatic solvents may be mixed.

<When a cyclic carbonate having a fluorine atom is used as an auxiliary>
In the present invention, when a cyclic carbonate having a fluorine atom is used as an auxiliary, one of the non-aqueous solvents exemplified above may be used alone as the non-aqueous solvent other than the cyclic carbonate having a fluorine atom, and two or more kinds may be used. May be used in any combination and in any ratio.
For example, one of the preferable combinations of the non-aqueous solvent is a combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate.

Among them, the total of the cyclic carbonate having no fluorine atom and the chain carbonate occupying the nonaqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, further preferably 90% by volume or more, and The proportion of the cyclic carbonate having no fluorine atom to the total of the cyclic carbonate having no fluorine atom and the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and still more preferably 15% by volume or more. Yes, it is preferably at most 50% by volume, more preferably at most 35% by volume, further preferably at most 30% by volume, particularly preferably at most 25% by volume.
When a combination of these non-aqueous solvents is used, the balance between the cycle characteristics and the high-temperature storage characteristics (particularly, the remaining capacity and high-load discharge capacity after high-temperature storage) of a battery manufactured using the combination may be improved.

For example, specific examples of preferred combinations of a cyclic carbonate and a chain carbonate having no fluorine atom include:
Ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and ethyl methyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate and diethyl carbonate and ethyl methyl carbonate, ethylene carbonate Dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, ethyl methyl carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, and the like.

  Among the combinations of cyclic carbonates having no fluorine atom and chain carbonates, those containing asymmetric chain alkyl carbonates as chain carbonates are more preferable, particularly, ethylene carbonate and ethyl methyl carbonate, propylene carbonate and ethyl. Methyl carbonate, ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate, ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate, propylene carbonate, ethyl methyl carbonate, and dimethyl carbonate, propylene carbonate, ethyl methyl carbonate, and diethyl carbonate have cycle characteristics and high current. This is preferable because the discharge characteristics are well balanced.

Among them, the asymmetric chain carbonates are preferably ethyl methyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.
When dimethyl carbonate is contained in the non-aqueous solvent, the proportion of dimethyl carbonate in the total non-aqueous solvent is preferably at least 10% by volume, more preferably at least 20% by volume, further preferably at least 25% by volume, particularly preferably at least 25% by volume. It is preferably at least 30% by volume, more preferably at most 90% by volume, more preferably at most 80% by volume, still more preferably at most 75% by volume, particularly preferably at most 70% by volume, The load characteristics of the battery may be improved.

Above all, by containing dimethyl carbonate and ethyl methyl carbonate, and by increasing the content of dimethyl carbonate to be greater than the content of ethyl methyl carbonate, the battery characteristics after high-temperature storage are improved while maintaining the electrical conductivity of the electrolytic solution. Is preferred.
The volume ratio of dimethyl carbonate to ethyl methyl carbonate (dimethyl carbonate / ethyl methyl carbonate) in the total nonaqueous solvent is 1.1 or more in terms of improving the electric conductivity of the electrolytic solution and improving the battery characteristics after storage. Is preferably 1.5 or more, more preferably 2.5 or more. The volume ratio (dimethyl carbonate / ethyl methyl carbonate) is preferably 40 or less, more preferably 20 or less, further preferably 10 or less, and particularly preferably 8 or less, from the viewpoint of improving battery characteristics.

In the combination mainly composed of a cyclic carbonate and a chain carbonate having no fluorine atom, cyclic carboxylate esters, chain carboxylate esters, cyclic ethers, chain ethers, sulfur-containing organic solvent, phosphorus-containing Other solvents such as an organic solvent and an aromatic fluorinated solvent may be mixed.
In this specification, the volume of the non-aqueous solvent is a value measured at 25 ° C., but for a solid such as ethylene carbonate at 25 ° C., the value measured at the melting point is used.

1-5. In the non-aqueous electrolyte secondary battery of the present invention, in addition to the compound represented by the general formula (A), a cyclic carbonate having a carbon-carbon unsaturated bond, and a cyclic carbonate having a fluorine atom, Auxiliaries may be used as appropriate. Examples of the auxiliary include the following isocyanate compounds, acid anhydride compounds, fluorinated unsaturated cyclic carbonates, compounds having a triple bond, and other auxiliary agents.

1-5-1. Isocyanate Compound The type of the isocyanate compound is not particularly limited as long as the compound has an isocyanate group in the molecule.
Specific examples of the isocyanate compound include, for example,
Hydrocarbon monoisocyanate compounds such as methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, t-butyl isocyanate, pentyl isocyanate, hexyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, and fluorophenyl isocyanate;
Monoisocyanate compounds having a carbon-carbon unsaturated bond, such as vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, and propynyl isocyanate;
Monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1,3-diisocyanate Natopropane, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5 Diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6 Diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, xylene diisocyanate, tolylene diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanato Methyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1 ′ Diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, bicyclo [2.2.1] heptane-2, 5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate), isophorone diisocyanate, carbonyl diisocyanate, 1,4-diisocyanatobutane-1,4-dione, Hydrocarbon diisocyanate compounds such as 1,5-diisocyanatopentane-1,5-dione, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate;
Isocyanate compounds such as diisocyanatosulfone, (ortho-, meta-, para-) toluenesulfonyl isocyanate, benzenesulfonyl isocyanate, fluorosulfonyl isocyanate, phenoxysulfonyl isocyanate, pentafluorophenoxysulfonyl isocyanate, methoxysulfonyl isocyanate;
And the like.

Among them, monoisocyanate compounds having a carbon-carbon unsaturated bond such as vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, and propynyl isocyanate;
Monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1,3-bis ( Isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4'-diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6- Diylbis (methyl isocyanate), isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate DOO, hydrocarbon diisocyanate compounds such as 2,4,4-trimethylhexamethylene diisocyanate;
Isocyanate compounds such as diisocyanatosulfone, (ortho-, meta-, para-) toluenesulfonyl isocyanate, benzenesulfonylisocyanate, fluorosulfonyl isocyanate, phenoxysulfonyl isocyanate, pentafluorophenoxysulfonyl isocyanate, methoxysulfonyl isocyanate;
Is preferred from the viewpoint of improving cycle characteristics and storage characteristics.

More preferred are allyl isocyanate, hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, diisocyanatosulfone, (ortho-, meta-, para-) toluenesulfonyl isocyanate, and particularly preferred is hexamethylene Diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, (ortho-, meta-, para-) toluenesulfonyl isocyanate, most preferably hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane is there.
Further, as the isocyanate compound, an isocyanate compound having a branched chain is preferable.

  The isocyanate compound used in the present invention may be a trimer compound derived from a compound having at least two isocyanate groups in the molecule, or an aliphatic polyisocyanate to which a polyhydric alcohol has been added. For example, biuret, isocyanurate, adduct, and bifunctional type modified polyisocyanate represented by the following general formulas (1-2-1) to (1-2-4) can be exemplified (the following general formula: In (1-2-1) to (1-2-4), R and R 'are each independently any hydrocarbon group).

  The compound having at least two isocyanate groups in the molecule used in the present invention also includes a so-called blocked isocyanate which has been improved in storage stability by being blocked with a blocking agent. Examples of the blocking agent include alcohols, phenols, organic amines, oximes, and lactams. Specifically, n-butanol, phenol, tributylamine, diethylethanolamine, methylethylketoxime, ε-caprolactam And the like.

In order to promote a reaction based on a compound having at least two isocyanate groups in a molecule and to obtain a higher effect, a metal catalyst such as dibutyltin dilaurate or the like, 1,8-diazabicyclo [5.4.0] undecene- It is also preferable to use an amine catalyst such as 7 in combination.
Further, as the compound having an isocyanate group, one kind may be used alone, and two kinds or more may be used in optional combination and ratio.

The amount of the compound having an isocyanate group with respect to the entire non-aqueous electrolyte of the present invention is not limited, and is arbitrary as long as the effect of the present invention is not significantly impaired. 001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, further preferably The content is 2% by mass or less, particularly preferably 1% by mass or less, most preferably 0.5% by mass or less.
When the above range is satisfied, effects such as output characteristics, load characteristics, cycle characteristics, and high-temperature storage characteristics are further improved.

1-5-2. Acid anhydride compounds Acid anhydride compounds include carboxylic anhydrides, sulfuric anhydrides, nitric anhydrides, sulfonic anhydrides, phosphoric anhydrides, phosphorous anhydrides, and cyclic acid anhydrides, chains. The structure is not particularly limited as long as it is an acid anhydride compound without being limited by the acid anhydride.

Specific examples of the acid anhydride compound include, for example,
Malonic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, maleic anhydride, citraconic anhydride, 2,3-dimethylmaleic anhydride, glutaconic anhydride, itaconic anhydride, phthalic anhydride, phenylmaleic anhydride 2,2-diphenylmaleic anhydride, cyclohexane-1,2-dicarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, , 4'-oxydiphthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, methyl-5-norbornene-2,3-dicarboxylic anhydride, phenylsuccinic anhydride, 2-phenylglutaric anhydride , Allyl succinic anhydride, 2-buten-11-yl succinic anhydride, (2-methyl-2-propenyl) succinic anhydride, tetra Fluorosuccinic anhydride, diacetyl-tartaric anhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5- (2,5-dioxo Tetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, methacrylic anhydride, acrylic anhydride, crotonic anhydride, methanesulfonic anhydride, trifluoromethanesulfonic anhydride, nona Fluorobutanesulfonic anhydride, acetic anhydride and the like.

Of these,
Succinic anhydride, maleic anhydride, citraconic anhydride, phenylmaleic anhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5- (2 , 5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, allylsuccinic anhydride, acetic anhydride, methacrylic anhydride, acrylic anhydride, and methanesulfonic anhydride. preferable.
As the acid anhydride compound, one kind may be used alone, and two kinds or more may be used in optional combination and ratio.

The amount of the acid anhydride compound to be added to the whole non-aqueous electrolyte of the present invention is not limited, and is arbitrary as long as the effect of the present invention is not significantly impaired. % By mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 2% by mass or less. It is contained at a concentration of not more than 1% by mass, particularly preferably not more than 1% by mass, most preferably not more than 0.5% by mass.
When the above range is satisfied, effects such as output characteristics, load characteristics, cycle characteristics, and high-temperature storage characteristics are further improved.

1-5-3. Fluorinated unsaturated cyclic carbonate As the fluorinated cyclic carbonate, it is also preferable to use a cyclic carbonate having an unsaturated bond and a fluorine atom (hereinafter sometimes referred to as “fluorinated unsaturated cyclic carbonate”). The number of fluorine atoms in the fluorinated unsaturated cyclic carbonate is not particularly limited as long as it is one or more. Among them, the number of fluorine atoms is usually 6 or less, preferably 4 or less, and 1 or 2 is most preferred.

Examples of the fluorinated unsaturated cyclic carbonate include a fluorinated vinylene carbonate derivative, a fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond, and the like.
As the fluorinated vinylene carbonate derivative, 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-5- Vinyl vinylene carbonate and the like.

As a fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond,
4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene Carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-f Oro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate.

Among them, preferred fluorinated unsaturated cyclic carbonates include:
4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro- 4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate 4,5-difluoro-4,5-divinyl ethylene carbonate, and 4,5-difluoro-4,5-diallyl carbonate. These are more preferably used because they form a stable interfacial protective film.

The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 50 or more and 250 or less. Within this range, the solubility of the fluorinated unsaturated cyclic carbonate in the non-aqueous electrolyte is easily ensured, and the effect of the present invention is easily exhibited.
The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and the fluorinated unsaturated cyclic carbonate can be produced by arbitrarily selecting a known method. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

As the fluorinated unsaturated cyclic carbonate, one kind may be used alone, and two kinds or more may be used in optional combination and ratio. The blending amount of the fluorinated unsaturated cyclic carbonate is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired.
The compounding amount of the fluorinated unsaturated cyclic carbonate is usually preferably at least 0.01% by mass, more preferably at least 0.1% by mass, further preferably at least 0.5% by mass in 100% by mass of the nonaqueous electrolyte. And preferably at most 10% by mass, more preferably at most 5% by mass, further preferably at most 3% by mass, particularly preferably at most 2% by mass.
Within this range, the non-aqueous electrolyte secondary battery can easily exhibit a sufficient effect of improving the cycle characteristics, and the high-temperature storage characteristics are reduced, the amount of generated gas is increased, and the discharge capacity retention ratio is reduced. It is easy to avoid the situation.

1-5-4. Compound having a triple bond The compound having a triple bond is not particularly limited as long as it has one or more triple bonds in the molecule.
Specific examples of the compound having a triple bond include, for example, the following compounds.
1-pentin, 2-pentyne, 1-hexyne, 2-hexyne, 3-hexyne, 1-heptin, 2-heptin, 3-heptin, 1-octin, 2-octin, 3-octyne, 4-octyne, 1-octin Nonin, 2-nonine, 3-nonine, 4-nonine, 1-dodecine, 2-dodecine, 3-dodecine, 4-dodecine, 5-dodecine, phenylacetylene, 1-phenyl-1-propyne, 1-phenyl-2 -Propyne, 1-phenyl-1-butyne, 4-phenyl-1-butyne, 4-phenyl-1-butyne, 1-phenyl-1-pentyne, 5-phenyl-1-pentyne, 1-phenyl-1-hexyne , 6-phenyl-1-hexyne, diphenylacetylene, 4-ethynyltoluene, dicyclohexylacetylene and other hydrocarbon compounds;

2-propynylmethyl carbonate, 2-propynylethyl carbonate, 2-propynylpropyl carbonate, 2-propynylbutyl carbonate, 2-propynylphenyl carbonate, 2-propynylcyclohexyl carbonate, di-2-propynyl carbonate, 1-methyl-2-propynyl Methyl carbonate, 1,1-dimethyl-2-propynylmethyl carbonate, 2-butynylmethyl carbonate, 3-butynylmethyl carbonate, 2-pentynylmethyl carbonate, 3-pentynylmethyl carbonate, 4-pentynylmethyl carbonate, etc. Monocarbonates of:
2-butyne-1,4-diol dimethyl dicarbonate, 2-butyne-1,4-diol diethyl dicarbonate, 2-butyne-1,4-diol dipropyl dicarbonate, 2-butyne-1,4-diol dibutyl Dicarbonates such as dicarbonate, 2-butyne-1,4-diol diphenyl dicarbonate and 2-butyne-1,4-diol dicyclohexyl dicarbonate;

2-propynyl acetate, 2-propynyl propionate, 2-propynyl butyrate, 2-propynyl benzoate, 2-propynyl cyclohexylcarboxylate, 1,1-dimethyl-2-propynyl acetate, 1,1-dimethyl-2-propionate Propynyl, 1,1-dimethyl-2-propynyl butyrate, 1,1-dimethyl-2-propynyl benzoate, 1,1-dimethyl-2-propynyl cyclohexylcarboxylate, 2-butynyl acetate, 3-butynyl acetate, 2-acetic acid -Pentynyl, 3-pentynyl acetate, 4-pentynyl acetate, methyl acrylate, ethyl acrylate, propyl acrylate, vinyl acrylate, 2-propenyl acrylate, 2-butenyl acrylate, 3-butenyl acrylate, methyl methacrylate , Ethyl methacrylate, propyl methacrylate, methacrylate Vinyl acrylate, 2-propenyl methacrylate, 2-butenyl methacrylate, 3-butenyl methacrylate, methyl 2-propinate, ethyl 2-propinate, propyl 2-propinate, vinyl 2-propinate, 2-propynate 2-propenyl, 2-butenyl 2-propinate, 3-butenyl 2-propinate, methyl 2-butyrate, ethyl 2-butyrate, propyl 2-butyrate, vinyl 2-butyrate, 2-butyric acid 2- Propenyl, 2-butenyl 2-butyrate, 3-butenyl 2-butyrate, methyl 3-butyrate, ethyl 3-butyrate, propyl 3-butyrate, vinyl 3-butyrate, 2-propenyl 3-butyrate, 2-butenyl 3-butyrate, 3-butenyl 3-butyrate, methyl 2-pentate, ethyl 2-pentate, propyl 2-pentate, 2- Vinyl pentate, 2-propenyl 2-pentate, 2-butenyl 2-pentate, 3-butenyl 2-pentate, methyl 3-pentate, ethyl 3-pentate, propyl 3-pentate, 3-pentynoate Vinyl, 2-propenyl 3-pentate, 2-butenyl 3-pentate, 3-butenyl 3-pentate, methyl 4-pentate, ethyl 4-pentate, propyl 4-pentate, vinyl 4-pentate, Monocarboxylic acid esters such as 2-propenyl 4-pentate, 2-butenyl 4-pentate, 3-butenyl 4-pentate;
2-butyne-1,4-diol diacetate, 2-butyne-1,4-diol dipropionate, 2-butyne-1,4-diol dibutyrate, 2-butyne-1,4-diol dibenzoate, 2-butyne Dicarboxylic acid esters such as -1,4-diol dicyclohexanecarboxylate;

  Methyl oxalate 2-propynyl, ethyl oxalate 2-propynyl, propyl oxalate 2-propynyl, 2-propynyl vinyl oxalate, allyl oxalate 2-propynyl, di-2-propynyl oxalate, 2-butynyl methyl oxalate, 2-butynyl ethyl oxalate, 2-butynyl propyl oxalate, 2-butynyl vinyl oxalate, allyl 2-butynyl oxalate, di-2-butynyl oxalate, 3-butynyl methyl oxalate, 3-butynyl ethyl oxalate Oxalic acid diesters such as 3-butynylpropyl oxalate, 3-butynylvinyl oxalate, allyl oxalate 3-butynyl, and di-3-butynyl oxalate;

  Methyl (2-propynyl) (vinyl) phosphine oxide, divinyl (2-propynyl) phosphine oxide, di (2-propynyl) (vinyl) phosphine oxide, di (2-propenyl) (2-propynyl) phosphine oxide, di (2 Phosphine oxides such as -propynyl) (2-propenyl) phosphine oxide, di (3-butenyl) (2-propynyl) phosphine oxide, and di (2-propynyl) (3-butenyl) phosphine oxide;

  2-propynyl methyl (2-propenyl) phosphinate, 2-propynyl 2-butenyl (methyl) phosphinate, 2-propynyl di (2-propenyl) phosphinate, 2-propynyl di (3-butenyl) phosphinate, methyl ( 1,1-dimethyl-2-propynyl 2-propenyl) phosphinate, 1,1-dimethyl-2-propynyl 2-butenyl (methyl) phosphinate, 1,1-dimethyl-2-di (2-propenyl) phosphinate Propynyl, 1,1-dimethyl-2-propynyl di (3-butenyl) phosphinate, 2-propenyl methyl (2-propynyl) phosphinate, 3-butenyl methyl (2-propynyl) phosphinate, di (2-propynyl) ) 2-propenyl phosphinate, 3-butenyl di (2-propynyl) phosphinate, 2 Propynyl (2-propenyl) phosphinic acid 2-propenyl, and 2-propynyl (2-propenyl) phosphinic acid 3-phosphinic acid esters butenyl;

  Methyl 2-propenylphosphonate 2-propynyl, methyl 2-butenylphosphonate (2-propynyl), 2-propenylphosphonic acid (2-propynyl) (2-propenyl), 3-butenylphosphonic acid (3-butenyl) (2-propynyl) ), 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl), 2-butenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl), 2-propenylphosphonic acid (1,1 -Dimethyl-2-propynyl) (2-propenyl), and 3-butenylphosphonic acid (3-butenyl) (1,1-dimethyl-2-propynyl), methylphosphonic acid (2-propynyl) (2-propenyl), methylphosphonic acid (3-butenyl) (2-propynyl), methylphosphonic acid (1,1-dimethyl-2-propyl) Pinyl) (2-propenyl), methylphosphonic acid (3-butenyl) (1,1-dimethyl-2-propynyl), ethylphosphonic acid (2-propynyl) (2-propenyl), ethylphosphonic acid (3-butenyl) ( Phosphonic acid esters such as 2-propynyl), ethylphosphonic acid (1,1-dimethyl-2-propynyl) (2-propenyl), and ethylphosphonic acid (3-butenyl) (1,1-dimethyl-2-propynyl) ;

(Methyl) phosphate (2-propenyl) (2-propynyl), (ethyl) phosphate (2-propenyl) (2-propynyl), (2-butenyl) (methyl) (2-propynyl), phosphoric acid (2-butenyl) (ethyl) (2-propynyl), (1,1-dimethyl-2-propynyl) phosphate (methyl) (2-propenyl), (1,1-dimethyl-2-propynyl) phosphate ( Ethyl) (2-propenyl), (2-butenyl) phosphate (1,1-dimethyl-2-propynyl) (methyl), and (2-butenyl) (ethyl) (1,1-dimethyl-2-phosphate) Phosphate esters such as propynyl).
Of these, compounds having an alkynyloxy group are preferable because they form a negative electrode coating more stably in an electrolytic solution.

further,
2-propynylmethyl carbonate, di-2-propynyl carbonate, 2-butyne-1,4-diol dimethyl dicarbonate, 2-propynyl acetate, 2-butyne-1,4-diol diacetate, methyl oxalate 2-propynyl, Compounds such as di-2-propynyl oxalate are particularly preferred from the viewpoint of improving storage characteristics.

  As the compound having a triple bond, one type may be used alone, or two or more types may be used in optional combination and ratio. The compounding amount of the compound having a triple bond with respect to the whole non-aqueous electrolyte of the present invention is not limited, and is arbitrary as long as the effect of the present invention is not significantly impaired. 01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less. Let it. When the above range is satisfied, effects such as output characteristics, load characteristics, cycle characteristics, and high-temperature storage characteristics are further improved.

1-5-5. Other auxiliaries As other auxiliaries, known auxiliaries other than the above auxiliaries can be used. Other auxiliaries include
Carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate;
Spiro compounds such as 2,4,8,10-tetraoxaspiro [5.5] undecane and 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane;
Ethylene sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, sulfolene, diphenylsulfone, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide, vinyl Methyl sulfonate, ethyl vinyl sulfonate, allyl vinyl sulfonate, propargyl vinyl sulfonate, methyl allyl sulfonate, ethyl allyl sulfonate, allyl allyl sulfonate, propargyl allyl sulfonate, 1,2-bis (vinyl sulfonyloxy) Sulfur-containing compounds such as ethane;

Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide;
Trimethyl phosphite, triethyl phosphite, triphenyl phosphite, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl methyl phosphonate, diethyl ethyl phosphonate, dimethyl vinyl phosphonate, diethyl vinyl phosphonate, dimethyl phosphine Phosphorus-containing compounds such as methyl acrylate, ethyl diethyl phosphinate, trimethyl phosphine oxide, and triethyl phosphine oxide;

Hydrocarbon compounds such as heptane, octane, nonane, decane and cycloheptane;
Fluorinated aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride;
2-propynyl 2- (diethoxyphosphoryl) acetate, 1-methyl-2-propynyl 2- (diethoxyphosphoryl) acetate, 1,1-dimethyl-2-propynyl 2- (diethoxyphosphoryl) acetate, pentafluorophenylmethane Sulfonate, pentafluorophenyltrifluoromethanesulfonate, pentafluorophenyl acetate, pentafluorophenyl trifluoroacetate, methylpentafluorophenyl carbonate, 2-propynyl 2- (methanesulfonyloxy) propionate, 2- (methanesulfonyloxy) propionate 2 -Methyl, 2-ethyl 2- (methanesulfonyloxy) propionate, 2-propynyl methanesulfonyloxyacetate, 2-methyl methanesulfonyloxyacetate, methanesulfonyloxy Ethyl acetate, lithium ethyl methyloxycarbonyl phosphonate, lithium ethyl ethyloxycarbonyl phosphonate, lithium ethyl 2-propynyloxycarbonyl phosphonate, lithium ethyl 1-methyl-2-propynyloxycarbonyl phosphonate, lithium ethyl 1,1-dimethyl-2-propynyl Oxycarbonylphosphonate, lithium methyl sulfate, lithium ethyl sulfate, lithium 2-propynyl sulfate, lithium 1-methyl-2-propynyl sulfate, lithium 1,1-dimethyl-2-propynyl sulfate, lithium 2,2,2-trifluoroethyl Sulfate, methyl trimethylsilyl sulfate, ethyl trimethylsilyl sulfate, 2-propynyl Trimethylsilyl sulfate, dilithium ethylene disulfate, 2-butyne-1,4-diyldimethanesulfonate, 2-butyne-1,4-diyldiethanesulfonate, 2-butyne-1,4-diyldiformate, 2-butyne-1, 4-diyl diacetate, 2-butyne-1,4-diyl dipropionate, 4-hexadiyne-1,6-diyl dimethanesulfonate, 2-propynyl methanesulfonate, 1-methyl-2-propynyl methanesulfonate, 1,1- Dimethyl-2-propynyl methanesulfonate, 2-propynylethanesulfonate, 2-propynylvinylsulfonate, methyl 2-propynyl carbonate, ethyl 2-propynyl carbonate, bis (2-propynyl) carbonate, methyl 2- Lopinyl oxalate, ethyl 2-propynyl oxalate, bis (2-propynyl) oxalate, 2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, di (2-propynyl) glutarate, 2,2-dioxide-1,2- Oxathiolan-4-yl acetate, 2,2-dioxide-1,2-oxathiolan-4-yl propionate, 5-methyl-1,2-oxathiolan-4-one 2,2-dioxide, 5,5-dimethyl-1 , 2-oxathiolan-4-one 2,2-dioxide, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl crotonate, 2- (2-isocyanatoethoxy) ethyl acrylate, 2- ( 2-isocyanate Toethoxy) ethyl methacrylate, 2- (2-isocyanatoethoxy) ethyl crotonate, 2-allylsuccinic anhydride, 2- (1-penten-3-yl) succinic anhydride, 2- (1-hexen-3-yl) ) Succinic anhydride, 2- (1-hepten-3-yl) succinic anhydride, 2- (1-octen-3-yl) succinic anhydride, 2- (1-nonen-3-yl) succinic anhydride Acid anhydride, 2- (3-buten-2-yl) succinic anhydride, 2- (2-methylallyl) succinic anhydride, 2- (3-methyl-3-buten-2-yl) succinic anhydride Objects and the like. These may be used alone or in combination of two or more. By adding these auxiliaries, capacity retention characteristics and cycle characteristics after high-temperature storage can be improved.

The amount of the other auxiliaries is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The other auxiliaries are preferably 0.01% by mass or more and 5% by mass or less in 100% by mass of the non-aqueous electrolyte. Within this range, the effects of the other auxiliary agents can be sufficiently exhibited, and a situation in which the battery characteristics such as high-load discharge characteristics are deteriorated can be easily avoided.
The compounding amount of other auxiliaries is more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, and more preferably 3% by mass or less, and further preferably 1% by mass or less. .

As described above, the above-mentioned non-aqueous electrolyte includes those present inside the non-aqueous electrolyte secondary battery according to the present invention.
Specifically, the components of the non-aqueous electrolyte such as a lithium salt, a solvent, and an auxiliary agent are separately synthesized, and a non-aqueous electrolyte is prepared from a substantially isolated component, and the method described below is used. In the case of a non-aqueous electrolyte solution in a non-aqueous electrolyte secondary battery obtained by injecting into a separately assembled battery, or the components of the non-aqueous electrolyte solution of the present invention are separately put in the battery When the same composition as the non-aqueous electrolyte of the present invention is obtained by mixing in the battery, further, a compound constituting the non-aqueous electrolyte of the present invention is generated in the non-aqueous electrolyte secondary battery, A case where the same composition as the non-aqueous electrolyte of the present invention is obtained is also included.

2. Battery Configuration The non-aqueous electrolyte solution of the present invention is suitable for use as an electrolyte solution for a secondary battery, for example, a lithium secondary battery among non-aqueous electrolyte batteries. Hereinafter, a non-aqueous electrolyte secondary battery using the non-aqueous electrolyte of the present invention will be described.
The non-aqueous electrolyte secondary battery of the present invention can have a known structure, and typically includes a negative electrode and a positive electrode capable of inserting and extracting ions (for example, lithium ions), and the above-described non-aqueous electrolyte of the present invention. An aqueous electrolyte.

2-1. Negative electrode The negative electrode active material used for the negative electrode is described below. The negative electrode active material is not particularly limited as long as it contains metal particles and graphite particles that can electrochemically occlude and release lithium ions and can be alloyed with Li. Specific examples include metal particles that can be alloyed with Li, carbonaceous materials (including graphite particles), alloy-based materials, lithium-containing metal composite oxide materials, and the like. These may be used alone or in any combination of two or more.

<Negative electrode active material>
Examples of the material that may or may not be included as the negative electrode active material include metal particles that can be alloyed with Li, a carbonaceous material, an alloy-based material, and a lithium-containing metal composite oxide material.
Examples of the carbonaceous material include (1) natural graphite, (2) artificial graphite, (3) amorphous carbon, (4) carbon-coated graphite, (5) graphite-coated graphite, and (6) resin-coated graphite. .

(1) Examples of the natural graphite include flaky graphite, flaky graphite, soil graphite, and / or graphite particles obtained by subjecting these graphites to raw materials such as spheroidization and densification. Among them, spherical or ellipsoidal graphite subjected to spheroidizing treatment is particularly preferable from the viewpoint of the filling property of the particles and the charge / discharge rate characteristics.
As an apparatus used for the spheroidizing treatment, for example, an apparatus that repeatedly applies mechanical action such as compression, friction, and shearing force including particle interaction mainly to impact force to particles can be used.
Specifically, the casing has a rotor with a number of blades installed inside, and the rotor rotates at a high speed, so that mechanical action such as impact compression, friction, and shearing force is applied to the carbon material introduced therein. And a device for performing a sphering treatment is preferable. Further, it is preferable to have a mechanism for repeatedly giving a mechanical action by circulating the carbon material.

  For example, when the spheroidizing treatment is performed using the above-described apparatus, the peripheral speed of the rotating rotor is preferably set to 30 to 100 m / sec, more preferably 40 to 100 m / sec, and more preferably 50 to 100 m / sec. More preferably, Further, the treatment can be carried out simply by passing the carbonaceous material, but it is preferable that the treatment is carried out by circulating or retaining in the apparatus for 30 seconds or more, and the treatment is preferably carried out by circulating or retaining in the apparatus for 1 minute or more. More preferred.

  (2) As artificial graphite, coal tar pitch, coal-based heavy oil, atmospheric residual oil, petroleum-based heavy oil, aromatic hydrocarbon, nitrogen-containing cyclic compound, sulfur-containing cyclic compound, polyphenylene, polyvinyl chloride, Organic compounds such as polyvinyl alcohol, polyacrylonitrile, polyvinyl butyral, natural polymers, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin, are usually in the range of 2500 ° C. or higher and usually 3200 ° C. or lower. Examples thereof include those manufactured by graphitization at a temperature, and pulverized and / or classified as necessary. At this time, a silicon-containing compound, a boron-containing compound, or the like can be used as a graphitization catalyst. Another example is artificial graphite obtained by graphitizing mesocarbon microbeads separated during the pitch heat treatment process. Further, artificial graphite as granulated particles composed of primary particles is also included. For example, by mixing a graphitizable carbonaceous material powder such as mesocarbon microbeads or coke with a graphitizable binder such as tar and pitch and a graphitizing catalyst, graphitizing, and pulverizing as necessary. Examples of the obtained graphite particles include a plurality of obtained flat particles, which are aggregated or bonded so that their alignment planes are non-parallel.

(3) As the amorphous carbon, amorphous carbon obtained by using a graphitizable carbon precursor such as tar or pitch as a raw material and heat-treating at least once in a non-graphitizable temperature range (range of 400 to 2200 ° C.) Examples include particles and amorphous carbon particles heat-treated using a non-graphitizable carbon precursor such as a resin as a raw material.
(4) The carbon-coated graphite can be obtained by mixing natural graphite and / or artificial graphite with a carbon precursor that is an organic compound such as tar, pitch or resin, and subjecting the mixture to a heat treatment at least once in the range of 400 to 2300 ° C. A carbon graphite composite in which natural graphite and / or artificial graphite is used as core graphite, and amorphous carbon covers the core graphite. The form of the composite may cover the entire surface or a part of the surface, or may be a composite of a plurality of primary particles using carbon derived from the carbon precursor as a binder. In addition, natural graphite and / or artificial graphite are reacted at high temperature with hydrocarbon gases such as benzene, toluene, methane, propane, and aromatic volatiles to deposit carbon on the graphite surface (CVD). A graphite composite can also be obtained.

(5) As the graphite-coated graphite, a mixture of natural graphite and / or artificial graphite and a carbon precursor of an easily graphitizable organic compound such as tar, pitch or resin is mixed once at a temperature of about 2400 to 3200 ° C. Natural graphite and / or artificial graphite obtained by the above heat treatment is used as nuclear graphite, and graphite-coated graphite in which a graphitized material covers the whole or a part of the surface of the nuclear graphite can be given.
(6) As the resin-coated graphite, natural graphite and / or artificial graphite is mixed with resin and the like, and natural graphite and / or artificial graphite obtained by drying at a temperature of less than 400 ° C. is used as core graphite. Resin-coated graphite coated with graphite may be used.

Further, as the carbonaceous materials (1) to (6), one kind may be used alone, and two kinds or more may be used in optional combination and ratio.
Examples of the organic compounds such as tar, pitch and resin used in the above (2) to (5) include coal-based heavy oil, direct current-based heavy oil, cracked petroleum heavy oil, aromatic hydrocarbon, and N-ring compound. , An S-ring compound, polyphenylene, an organic synthetic polymer, a natural polymer, a carbonizable organic compound selected from the group consisting of a thermoplastic resin and a thermosetting resin, and the like. Further, the raw material organic compound may be used by dissolving it in a low molecular weight organic solvent in order to adjust the viscosity at the time of mixing.

Further, as natural graphite and / or artificial graphite which is a raw material of nuclear graphite, natural graphite subjected to spheroidizing treatment is preferable.
As the alloy-based material used as the negative electrode active material, as long as it can occlude and release lithium, simple lithium, a simple metal and an alloy forming a lithium alloy, or oxides, carbides, nitrides, silicides, and sulfides thereof Or a compound such as a phosphide, and is not particularly limited. The elemental metal or alloy forming the lithium alloy is preferably a material containing a metal or metalloid element of group 13 and group 14 (that is, excluding carbon), and more preferably an elemental metal of aluminum, silicon and tin and An alloy or a compound containing these atoms. One of these may be used alone, or two or more thereof may be used in any combination and in any ratio.

<Physical properties of carbonaceous materials>
When a carbonaceous material is used as the negative electrode active material, the material preferably has the following physical properties.
(X-ray parameters)
The d value (interlayer distance) of the lattice plane (002 plane) of the carbonaceous material obtained by X-ray diffraction according to the Gakushin method is usually 0.335 nm or more, usually 0.360 nm or less, and 0.350 nm. Or less, more preferably 0.345 nm or less. The crystallite size (Lc) of the carbonaceous material determined by X-ray diffraction according to the Gakushin method is preferably 1.0 nm or more, and more preferably 1.5 nm or more.

(Volume-based average particle size)
The volume-based average particle diameter of the carbonaceous material is a volume-based average particle diameter (median diameter) determined by a laser diffraction / scattering method, and is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and more preferably 7 μm. The above is particularly preferred, and usually 100 μm or less, preferably 50 μm or less, more preferably 40 μm or less, further preferably 30 μm or less, and particularly preferably 25 μm or less.

If the volume-based average particle size is below the above range, the irreversible capacity may increase, leading to an initial battery capacity loss. On the other hand, when the ratio is more than the above range, when an electrode is produced by coating, the coating surface tends to be uneven, which may be undesirable in a battery manufacturing process.
The volume-based average particle size is measured by dispersing a carbon powder in a 0.2% by mass aqueous solution (about 10 mL) of a surfactant, polyoxyethylene (20) sorbitan monolaurate, and then performing a laser diffraction / scattering type particle size distribution. (For example, LA-700 manufactured by Horiba Ltd.). The median diameter determined by the measurement is defined as a volume-based average particle diameter of the carbonaceous material.

(Raman R value)
The Raman R value of the carbonaceous material is a value measured using a laser Raman spectrum method, and is usually 0.01 or more, preferably 0.03 or more, more preferably 0.1 or more, and usually 1. 5 or less, preferably 1.2 or less, more preferably 1 or less, particularly preferably 0.5 or less.

If the Raman R value is below the above range, the crystallinity of the particle surface becomes too high, and the number of sites where Li enters between layers may decrease with charge and discharge. That is, charge acceptability may decrease. In addition, when the negative electrode is densified by pressing after being applied to the current collector, the crystal is likely to be oriented in a direction parallel to the electrode plate, which may cause a decrease in load characteristics.
On the other hand, if it exceeds the above range, the crystallinity of the particle surface is reduced, the reactivity with the non-aqueous electrolyte is increased, and the efficiency may be reduced and the gas generation may be increased.

The measurement of the Raman spectrum is performed by using a Raman spectrometer (for example, a Raman spectrometer manufactured by JASCO Corporation) to allow the sample to naturally fall into the measurement cell and to fill the cell, and to apply argon ion laser light (or semiconductor This is performed by rotating the cell in a plane perpendicular to the laser beam while irradiating the cell with the laser beam. The resulting Raman spectrum, the intensity IA of a peak PA around 1580 cm ^-1, and measuring the intensity IB of the peak PB around 1360 cm ^-1, and calculates the intensity ratio R (R = IB / IA) . The Raman R value calculated by the measurement is defined as the Raman R value of the carbonaceous material.

The above Raman measurement conditions are as follows.
・ Laser wavelength: Ar ion laser 514.5 nm (semiconductor laser 532 nm)
-Measurement range: 1100 cm ^{-1 to} 1730 cm ^-1
Raman R value: background processing,
・ Smoothing processing: Simple average, convolution 5 points

(BET specific surface area)
BET specific surface area of the carbonaceous material is a value of the measured specific surface area using the BET method is usually 0.1 m ² · ^{g -1} or more, 0.7 m ² · ^{g -1} or more, 1. 0 m ² · ^{g -1} or more, and particularly preferably 1.5 m ² · ^{g -1} or more, generally not more than 100 m ² · ^{g -1,} preferably ^{25 m} 2 · ^{g -1} or less, 15 m ² · g ⁻¹ or less is more preferable, and 10 m ² · g ⁻¹ or less is particularly preferable.

When the value of the BET specific surface area falls below this range, the lithium acceptability at the time of charging when used as a negative electrode material is likely to be poor, lithium is likely to precipitate on the electrode surface, and the stability may be reduced. On the other hand, if it exceeds this range, when used as a negative electrode material, the reactivity with a non-aqueous electrolytic solution increases, gas generation tends to increase, and a preferable battery may not be obtained.
The measurement of the specific surface area by the BET method is performed by preliminarily drying the sample at 350 ° C. for 15 minutes under a nitrogen flow using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken), and then measuring the atmospheric pressure. Using a nitrogen helium mixed gas accurately adjusted so that the value of the relative pressure of nitrogen becomes 0.3, a nitrogen adsorption BET one-point method by a gas flow method is used.

(Roundness)
When the circularity is measured as the degree of sphere of the carbonaceous material, it is preferable to fall within the following range. The circularity is defined as “circularity = (perimeter of equivalent circle having the same area as the projected shape of the particle) / (actual perimeter of the projected shape of the particle)”. It becomes a true sphere.
The circularity of the carbonaceous material having a particle diameter in the range of 3 to 40 μm is preferably as close to 1 as possible, more preferably 0.1 or more, particularly preferably 0.5 or more, more preferably 0.8 or more, 0.85 or more is more preferable, and 0.9 or more is particularly preferable. The high current density charge / discharge characteristics improve as the circularity increases. Therefore, when the circularity is lower than the above range, the filling property of the negative electrode active material is reduced, the resistance between the particles is increased, and the high-current density charge / discharge characteristics in a short time may be reduced.

  The circularity is measured using a flow-type particle image analyzer (for example, FPIA manufactured by Sysmex Corporation). About 0.2 g of a sample is dispersed in a 0.2% by mass aqueous solution (about 50 mL) of a polyoxyethylene (20) sorbitan monolaurate as a surfactant, and irradiated with ultrasonic waves of 28 kHz for 1 minute at an output of 60 W. The detection range is specified to be 0.6 to 400 μm, and measurement is performed for particles having a particle size in the range of 3 to 40 μm.

  The method for improving the degree of circularity is not particularly limited, but it is preferable that the spherical shape is obtained by performing a spheroidizing treatment because the shape of the interparticle space when the electrode is formed is formed. Examples of the spheroidizing treatment include a method of mechanically approaching a spherical shape by applying a shear force and a compressive force, and a mechanical and physical treatment method of granulating a plurality of fine particles by a binder or an adhesive force of the particles themselves. Is mentioned.

(Tap density)
The tap density of the carbonaceous material is generally 0.1 g · cm ⁻³ or more, preferably 0.5 g · cm ⁻³ or more, more preferably 0.7 g · cm ⁻³ or more, and preferably 1 g · cm ⁻³ or more. particularly preferred, and is preferably 2 g · ^{cm -3} or less, more preferably 1.8 g · ^{cm -3} or less, 1.6 g · ^{cm -3} or less are particularly preferred. When the tap density is lower than the above range, when used as a negative electrode, the packing density is difficult to increase, and a high-capacity battery may not be obtained. On the other hand, when the ratio is more than the above range, voids between particles in the electrode become too small, and it becomes difficult to secure conductivity between particles, and it may be difficult to obtain preferable battery characteristics.

The tap density was measured by passing the sample through a sieve having an aperture of 300 μm, dropping the sample into a 20 cm ³ tapping cell, filling the sample up to the upper end surface of the cell, and then using a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Tapping with a stroke length of 10 mm is performed 1000 times using a tap denser), and the tap density is calculated from the volume at that time and the mass of the sample.

(Orientation ratio)
The orientation ratio of the carbonaceous material is usually 0.005 or more, preferably 0.01 or more, more preferably 0.015 or more, and usually 0.67 or less. When the orientation ratio is below the above range, the high-density charge / discharge characteristics may be reduced. Note that the upper limit of the above range is the theoretical upper limit of the orientation ratio of the carbonaceous material.
The orientation ratio is measured by X-ray diffraction after forming a sample under pressure. A molded body obtained by filling 0.47 g of the sample in a molding machine having a diameter of 17 mm and compressing the molded body at 58.8 MN · m ⁻² was set using clay to be flush with the surface of the sample holder for measurement. X-ray diffraction is measured. From the peak intensities of (110) diffraction and (004) diffraction of the obtained carbon, a ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated.

The X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Divergence slit = 0.5 degree Light receiving slit = 0.15 mm
Scattering slit = 0.5 degree, measurement range and step angle / measurement time:
(110) plane: 75 degrees ≦ 2θ ≦ 80 degrees 1 degree / 60 seconds (004) plane: 52 degrees ≦ 2θ ≦ 57 degrees 1 degree / 60 seconds

(Aspect ratio (powder))
The aspect ratio of the carbonaceous material is usually 1 or more, and usually 10 or less, preferably 8 or less, more preferably 5 or less. If the aspect ratio exceeds the above range, streaking or uniform coating surface may not be obtained at the time of forming the electrode plate, and the high current density charge / discharge characteristics may decrease. Note that the lower limit of the above range is the theoretical lower limit of the aspect ratio of the carbonaceous material.

  The measurement of the aspect ratio is performed by observing the particles of the carbonaceous material under magnification with a scanning electron microscope. 50 arbitrary graphite particles fixed on the end face of a metal having a thickness of 50 μm or less are selected, and the stage on which the sample is fixed is rotated and tilted for each of the particles, and the carbonaceous material particles are observed three-dimensionally. Is measured, and the shortest diameter B perpendicular to the longest diameter A is measured, and the average value of A / B is obtained.

(Coverage rate)
The negative electrode active material may be coated with a carbonaceous material or a graphite material. Among these, it is preferable to coat with an amorphous carbonaceous material from the viewpoint of acceptability of lithium ions, and the coating ratio is usually 0.5% or more and 30% or less, preferably 1% or more and 25% or less, more preferably. Is 2% or more and 20% or less. If the content is too large, the amorphous carbon portion of the negative electrode active material increases, and the reversible capacity when the battery is assembled tends to decrease. If the content is too small, the amorphous carbon portion is not uniformly coated on the graphite particles serving as the nucleus, and strong granulation is not performed. When pulverized after firing, the particle size tends to be too small.
The content (coverage) of the carbide derived from the organic compound of the finally obtained negative electrode active material is determined by the amount of the negative electrode active material, the amount of the organic compound, and the residual amount measured by a micro method in accordance with JIS K2270. The following formula can be used to calculate the charcoal content.
Formula: Coverage (%) of carbide derived from organic compound = (mass of organic compound × residual carbon ratio × 100) / {mass of negative electrode active material + (mass of organic compound × residual carbon ratio)}

(Internal porosity)
The internal porosity of the negative electrode active material is usually 1% or more, preferably 3% or more, more preferably 5% or more, and still more preferably 7% or more. Further, it is usually less than 50%, preferably 40% or less, more preferably 30% or less, and further preferably 20% or less. If the internal porosity is too small, the amount of liquid in the particles will decrease, and the charge / discharge characteristics will tend to deteriorate.If the internal porosity is too large, the interparticle gap will be small when the electrode is used, and the diffusion of electrolyte Tend to be insufficient. In addition, even if a material that buffers expansion and contraction of metal particles that can be alloyed with Li, such as amorphous carbon or a graphite material, a resin, is present in the gap or fills the gap. Good.

<Metal particles that can be alloyed with Li>
Techniques for confirming that the metal particles are metal particles that can be alloyed with Li include identification of the metal particle phase by X-ray diffraction, observation of the particle structure by an electron microscope, elemental analysis, and elemental analysis by X-ray fluorescence. Analysis and the like.
Any conventionally known metal particles that can be alloyed with Li can be used. However, from the viewpoint of capacity and cycle life, the metal particles are, for example, Fe, Co, Sb, Bi, Pb, Ni, and Ag. , Si, Sn, Al, Zr, Cr, P, S, V, Mn, As, Nb, Mo, Cu, Zn, Ge, In, Ti and W or a metal or a compound thereof. preferable. Further, an alloy composed of two or more kinds of metals may be used, and the metal particles may be alloy particles formed of two or more kinds of metal elements. Among these, a metal selected from the group consisting of Si, Sn, As, Sb, Al, Zn and W or a metal compound thereof is preferable.
Examples of the metal compound include a metal oxide, a metal nitride, and a metal carbide. Further, an alloy composed of two or more metals may be used.

Among metal particles that can be alloyed with Li, Si or a Si metal compound is preferable. The Si metal compound is preferably a Si metal oxide. Si or a Si metal compound is preferable in terms of increasing the capacity. In this specification, Si or a Si metal compound is collectively referred to as a Si compound. Specific examples of the Si compound include SiOx, SiNx, SiCx, and SiZxOy (Z = C, N). The Si compound is preferably a Si metal oxide, and the Si metal oxide is SiOx when represented by a general formula. This general formula SiOx is obtained by using Si dioxide (SiO2) and metal Si (Si) as raw materials, and the value of x is usually 0 ≦ x <2. SiOx has a larger theoretical capacity than graphite, and amorphous Si or nano-sized Si crystals allow alkali ions such as lithium ions to enter and exit more easily, and a high capacity can be obtained.
The Si metal oxide is specifically represented as SiOx, and x satisfies 0 ≦ x <2, more preferably 0.2 or more and 1.8 or less, and further preferably 0. 4 or more and 1.6 or less, particularly preferably 0.6 or more and 1.4 or less, and X = 0 is particularly preferable. Within this range, the irreversible capacity due to the combination of Li and oxygen can be reduced at the same time as having a high capacity.

-Average particle diameter of metal particles that can be alloyed with Li (d50)
The average particle diameter (d50) of the metal particles that can be alloyed with Li is usually 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and still more preferably 0.3 μm, from the viewpoint of cycle life. It is usually 10 μm or less, preferably 9 μm or less, more preferably 8 μm or less. When the average particle diameter (d50) is within the above range, volume expansion due to charge and discharge is reduced, and good cycle characteristics can be obtained while maintaining charge and discharge capacity.
The average particle diameter (d50) is determined by a laser diffraction / scattering type particle size distribution measuring method or the like.

-BET specific surface area of metal particles that can be alloyed with Li The specific surface area of the metal particles that can be alloyed with Li is usually 0.5 to 60 m2 / g, and preferably 1 to 40 m2 / g by the BET method. When the specific surface area of the metal particles that can be alloyed with Li by the BET method is within the above range, the charge / discharge efficiency and the discharge capacity of the battery are high, lithium can be taken in and out at high speed charge / discharge, and the rate characteristics are excellent.

-Oxygen content of metal particles that can be alloyed with Li The oxygen content of metal particles that can be alloyed with Li is not particularly limited, but is usually 0.01 to 8% by mass and 0.05 to 5% by mass. Preferably, there is. The oxygen distribution state in the particle may be present near the surface, inside the particle, or uniformly in the particle, but is preferably present near the surface. It is preferable that the oxygen content of the metal particles that can be alloyed with Li be within the above range, since the strong expansion of Si and O suppresses volume expansion due to charge and discharge, and is excellent in cycle characteristics.

<Negative electrode active material containing metal particles and graphite particles that can be alloyed with Li>
In the present invention, the negative electrode active material containing metal particles and graphite particles that can be alloyed with Li is a mixture in which metal particles and graphite particles that can be alloyed with Li are mixed in a state of particles independent of each other. Alternatively, a composite in which metal particles that can be alloyed with Li are present on the surface or inside of the graphite particles may be used. In the present specification, the composite (also referred to as composite particle) is not particularly limited as long as it contains metal particles and a carbonaceous substance that can be alloyed with Li, but preferably, Li and an alloy The metal particles and the carbonaceous material which can be converted are particles integrated by physical and / or chemical bonding. In a more preferred form, the metal particles and the carbonaceous material that can be alloyed with Li are present in a state in which each solid component is dispersed within the particles to the extent that they are present at least on both the surface of the composite particles and the inside of the bulk. In which carbonaceous material is present to integrate them by physical and / or chemical bonding. A more specific preferred form is a composite material composed of at least metal particles and graphite particles that can be alloyed with Li, in which graphite particles, preferably natural graphite, have a folded structure having a curved surface. In addition, the negative electrode active material is characterized in that metal particles which can be alloyed with Li are present in gaps in the folded structure having the curved surface. In addition, the gap may be a void, or a substance that buffers expansion and contraction of metal particles that can be alloyed with Li, such as amorphous carbon, graphite, and resin, is present in the gap. Is also good.

The content ratio of the metal particles that can be alloyed with Li The content ratio of the metal particles that can be alloyed with Li is 1% by mass or more, preferably 2% by mass, based on the total of the metal particles that can be alloyed with Li and the graphite particles. That is all. Further, it is usually 99% by mass or less, preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, still more preferably 25% by mass or less, even more preferably 20% by mass or less, particularly preferably Preferably it is 15% by mass or less, most preferably 10% by mass or less. Within this range, the coating made of the compound represented by the formula (A) can suitably cover metal particles that can be alloyed with Li, and can improve the adhesion to graphite particles. preferable.

  The alloy-based material negative electrode can be manufactured using any known method. Specifically, as a method of manufacturing the negative electrode, for example, a method in which the above-described negative electrode active material to which a binder or a conductive material is added is roll-formed as it is to form a sheet electrode, or a compression-formed pellet electrode is formed. Usually, the above negative electrode is formed on a current collector for the negative electrode (hereinafter sometimes referred to as a “negative electrode current collector”) by a method such as a coating method, a vapor deposition method, a sputtering method, and a plating method. A method of forming a thin film layer (a negative electrode active material layer) containing an active material is used. In this case, a binder, a thickener, a conductive material, a solvent, etc. are added to the above-mentioned negative electrode active material to form a slurry, which is applied to a negative electrode current collector, dried, and then pressed to increase the density. Then, a negative electrode active material layer is formed on the negative electrode current collector.

Examples of the material of the negative electrode current collector include steel, copper alloy, nickel, nickel alloy, and stainless steel. Among these, copper foil is preferred from the viewpoint of easy processing into a thin film and the cost.
The thickness of the negative electrode current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less. If the thickness of the negative electrode current collector is too large, the capacity of the whole battery may be too low, and if too thin, the handling may be difficult.

  Note that, in order to improve the binding effect with the negative electrode active material layer formed on the surface, it is preferable that the surface of these negative electrode current collectors be previously subjected to a surface roughening treatment. Examples of the surface roughening method include blasting, rolling with a rough roll, a polishing cloth, a grinding stone, an emery buff, a wire brush equipped with a steel wire, etc. on which the abrasive particles are fixed. Polishing method, electrolytic polishing method, chemical polishing method and the like.

  Further, in order to reduce the mass of the negative electrode current collector and improve the energy density per mass of the battery, a perforated type negative electrode current collector such as an expanded metal or a punched metal can be used. The mass of this type of negative electrode current collector can be freely changed by changing its aperture ratio. In addition, when a negative electrode active material layer is formed on both surfaces of this type of negative electrode current collector, the negative electrode active material layer is less likely to peel off due to a rivet effect through this hole. However, when the aperture ratio is too high, the contact area between the negative electrode active material layer and the negative electrode current collector becomes small, so that the bonding strength may be lowered.

The slurry for forming the negative electrode active material layer is usually prepared by adding a binder, a thickener and the like to the negative electrode material. In this specification, the term “negative electrode material” refers to a material obtained by combining a negative electrode active material and a conductive material.
It is preferable that the content of the negative electrode active material in the negative electrode material is usually 70% by mass or more, particularly 75% by mass or more, and usually 97% by mass or less, particularly 95% by mass or less. When the content of the negative electrode active material is too small, the capacity of a secondary battery using the obtained negative electrode tends to be insufficient. It is difficult to secure conductivity. When two or more negative electrode active materials are used in combination, the total amount of the negative electrode active materials may satisfy the above range.

  Examples of the conductive material used for the negative electrode include metal materials such as copper and nickel; and carbon materials such as graphite and carbon black. One of these may be used alone, or two or more thereof may be used in any combination and in any ratio. In particular, it is preferable to use a carbon material as the conductive material because the carbon material also functions as an active material. The content of the conductive material in the negative electrode material is usually at least 3% by mass, particularly at least 5% by mass, and usually at most 30% by mass, particularly preferably at most 25% by mass. If the content of the conductive material is too small, the conductivity tends to be insufficient. If the content is too large, the content of the negative electrode active material and the like tends to be relatively low, so that the battery capacity and strength tend to decrease. When two or more conductive materials are used in combination, the total amount of the conductive materials may satisfy the above range.

  As the binder used for the negative electrode, any material can be used as long as it is a safe material for the solvent and the electrolytic solution used in manufacturing the electrode. For example, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, styrene / butadiene rubber / isoprene rubber, butadiene rubber, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer and the like can be mentioned. One of these may be used alone, or two or more thereof may be used in any combination and in any ratio. The content of the binder is preferably at least 0.5 part by mass, more preferably at least 1 part by mass, and usually at most 10 parts by mass, particularly preferably at most 8 parts by mass, per 100 parts by mass of the negative electrode material. If the content of the binder is too small, the strength of the obtained negative electrode tends to be insufficient, and if the content is too large, the content of the negative electrode active material and the like tends to be relatively small, so that the battery capacity and conductivity tend to be insufficient. Becomes When two or more binders are used in combination, the total amount of the binders may satisfy the above range.

  Examples of the thickener used for the negative electrode include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein. One of these may be used alone, or two or more thereof may be used in any combination and in any ratio. The thickener may be used as needed, but when used, the content of the thickener in the negative electrode active material layer is usually used in a range of 0.5% by mass or more and 5% by mass or less. Is preferred.

  The slurry for forming the negative electrode active material layer is prepared by mixing the above negative electrode active material with a conductive material, a binder, and a thickener as necessary, and using an aqueous solvent or an organic solvent as a dispersion medium. You. As the aqueous solvent, water is usually used, and an organic solvent such as an alcohol such as ethanol and a cyclic amide such as N-methylpyrrolidone is used together in an amount of 30% by mass or less based on water. Can also. As the organic solvent, usually, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic carbons such as anisole, toluene and xylene are usually used. Examples thereof include hydrogens, alcohols such as butanol and cyclohexanol, and among them, cyclic amides such as N-methylpyrrolidone and linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide are preferable. . One of these may be used alone, or two or more of them may be used in any combination and in any ratio.

  The obtained slurry is applied on the above-mentioned negative electrode current collector, dried, and then pressed to form a negative electrode active material layer. The method of application is not particularly limited, and a method known per se can be used. The method of drying is not particularly limited, and a known method such as natural drying, heating drying, and drying under reduced pressure can be used.

<Structure of negative electrode and fabrication method>
Any known method can be used for manufacturing the electrode as long as the effects of the present invention are not significantly impaired. For example, to form a slurry by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, and the like to the negative electrode active material, applying the slurry to a current collector, drying, and then pressing the slurry. Can be.
When an alloy-based material is used, a method of forming a thin film layer (negative electrode active material layer) containing the above-described negative electrode active material by a method such as a vapor deposition method, a sputtering method, and a plating method is also used.

(Electrode density)
Although the electrode structure when the negative electrode active material is formed into an electrode is not particularly limited, the density of the negative electrode active material present on the current collector is preferably 1 g · cm ⁻³ or more, and more preferably 1.2 g · cm ⁻³ or more. but more preferably, particularly preferably 1.3 g · ^{cm -3} or more, preferably 2.2 g · ^{cm -3} or less, more preferably 2.1 g · ^{cm -3} or less, 2.0 g · ^{cm -3} or less Further preferred is 1.9 g · cm ⁻³ or less. When the density of the negative electrode active material existing on the current collector exceeds the above range, the negative electrode active material particles are destroyed, the initial irreversible capacity increases, and the non-aqueous system near the current collector / negative electrode active material interface increases. In some cases, the charge / discharge characteristics of the high current density deteriorate due to the decrease in the permeability of the electrolyte. If the ratio is below the above range, the conductivity between the negative electrode active materials may decrease, the battery resistance may increase, and the capacity per unit volume may decrease.

2-2. Positive electrode <Positive electrode active material>
Hereinafter, the positive electrode active material (lithium transition metal-based compound) used for the positive electrode will be described.
<Lithium transition metal compound>
The lithium transition metal compound is a compound having a structure capable of desorbing and inserting Li ions, and examples thereof include a sulfide, a phosphate compound, and a lithium transition metal composite oxide. The sulfide, and compounds having a two-dimensional layered structure such as TiS ₂ and MoS _2, strong (in Me which various transition metals including Pb, Ag, and Cu) general formula _Me x _Mo 6 _S 8 represented by Schüberl compounds having a simple three-dimensional skeleton structure. Examples of the phosphate compound include those belonging to an olivine structure, and are generally represented by LiMePO ₄ (Me is at least one or more transition metals). Specifically, LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , LiMnPO _{4 and the} like. Examples of the lithium transition metal composite oxide include those belonging to a spinel structure capable of three-dimensional diffusion and a layered structure capable of two-dimensional diffusion of lithium ions. Those having a spinel structure are generally expressed as LiMe ₂ O ₄ (Me is at least one transition metal), and specifically, LiMn ₂ O ₄ , LiCoMnO ₄ , LiNi _0.5 Mn _1.5 O ₄ , LiCoVO _{4 and the} like. Those having a layered structure are generally represented as LiMeO ₂ (Me is at least one transition metal). LiCoO _{2 Specifically, LiNiO 2, LiNi 1-x} Co x O2, LiNi 1-x-y Co x Mn y O 2, LiNi 0.5 Mn 0.5 O 2, Li 1.2 Cr 0.4 Mn _0.4 O ₂ , Li _1.2 Cr _0.4 Ti _0.4 O ₂ , LiMnO _{2, and the} like.

<composition>
Further, the lithium-containing transition metal-based compound is, for example, a lithium transition metal-based compound represented by the following composition formula (F) or (G).
1) When the compound is a lithium transition metal compound represented by the following composition formula (F)
Li _{1 + x} MO ₂ ... (F)
However, x is usually 0 or more and 0.5 or less. M is an element composed of Ni and Mn or Ni, Mn and Co, and the Mn / Ni molar ratio is usually 0.1 or more and 5 or less. The Ni / M molar ratio is usually 0 or more and 0.5 or less. The Co / M molar ratio is usually 0 or more and 0.5 or less. It should be noted that the rich portion of Li represented by x may be replaced with a transition metal site M.

  In the composition formula (F), the atomic ratio of the amount of oxygen is described as 2 for convenience, but there may be some non-stoichiometry. Further, x in the above composition formula is a charged composition in the production stage of the lithium transition metal based compound. Normally, batteries on the market are aged after the batteries are assembled. Therefore, the amount of Li in the positive electrode may be deficient with charge and discharge. In that case, x in the case of discharging to 3 V may be measured to be -0.65 or more and 1 or less in composition analysis.

Further, the lithium transition metal-based compound obtained by firing at a high temperature in an oxygen-containing gas atmosphere in order to enhance the crystallinity of the positive electrode active material has excellent battery characteristics.
Further, the lithium transition metal-based compound represented by the composition formula (F) may be a solid solution with Li ₂ MO ₃ called a 213 layer as shown in the following general formula (F ′).
αLi ₂ MO _3. (1-α) LiM′O ₂ ... (F ′)
In the general formula, α is a number satisfying 0 <α <1.

M is at least one metal element having an average oxidation number of 4+, and specifically, is at least one metal element selected from the group consisting of Mn, Zr, Ti, Ru, Re, and Pt. .
M ′ is at least one metal element having an average oxidation number of 3+, preferably at least one metal element selected from the group consisting of V, Mn, Fe, Co and Ni, more preferably Is at least one metal element selected from the group consisting of Mn, Co and Ni.

2) When the compound is a lithium transition metal compound represented by the following general formula (G).
Li [LiaMbMn _2- ba] O _{4 + δ} (G)
Here, M is an element composed of at least one of transition metals selected from Ni, Cr, Fe, Co, Cu, Zr, Al and Mg.
The value of b is usually 0.4 or more and 0.6 or less.
When the value of b is within this range, the energy density per unit weight of the lithium transition metal-based compound is high.

  The value of a is usually 0 or more and 0.3 or less. In addition, a in the above composition formula is a charged composition in a production stage of the lithium transition metal-based compound. Normally, batteries on the market are aged after the batteries are assembled. Therefore, the amount of Li in the positive electrode may be deficient with charge and discharge. In that case, a in the case of discharging to 3 V may be measured to be -0.65 or more and 1 or less in composition analysis.

When the value of a is within this range, the energy density per unit weight of the lithium transition metal compound is not significantly impaired, and good load characteristics can be obtained.
Further, the value of δ is usually in the range of -0.5 to 0.5.
When the value of δ is in this range, the stability as a crystal structure is high, and the cycle characteristics and high-temperature storage characteristics of a battery having an electrode manufactured using this lithium transition metal-based compound are good.

Here, the chemical meaning of the lithium composition in the lithium-nickel-manganese-based composite oxide, which is the composition of the lithium transition metal-based compound, will be described in more detail below.
In order to obtain a and b in the composition formula of the lithium transition metal-based compound, each transition metal and lithium are analyzed by an inductively coupled plasma emission spectrometer (ICP-AES) to obtain a ratio of Li / Ni / Mn. It is calculated by the thing.

From a structural point of view, it is considered that the lithium related to a is substituted into the same transition metal site. Here, the average valence of M and manganese becomes larger than 3.5 due to the charge neutrality principle due to lithium according to a.
Further, the lithium transition metal based compound may be substituted with fluorine, such compounds are denoted as LiMn2O _4-x F _2x.

<blend>
Specific examples of the lithium transition metal based compound having the above composition include, for example, Li _{1 + x} Ni _0.5 Mn _0.5 O ₂ , Li _{1 + x} Ni _0.85 Co _0.10 Al _0.05 O ₂ , and Li _{1 + x} Ni _0.33 Mn _0.33 Co _0.33 O ₂ , Li _{1 + x} Ni _0.45 Mn _0.45 Co _0.1 O ₂ , Li _{1 + x} Mn _1.8 Al _0.2 O ₄ , Li _{1 + x} Mn _1.5 Ni _0.5 O _{4 and the} like. One of these lithium transition metal-based compounds may be used alone, or two or more thereof may be used as a blend.

<Introduction of foreign elements>
Further, a foreign element may be introduced into the lithium transition metal-based compound. As the different elements, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Ru, Rh, Pd, Ag, In, Sb, Te , Ba, Ta, Mo, W, Re, Os, Ir, Pt, Au, Pb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi , N, F, S, Cl, Br, I, As, Ge, P, Pb, Sb, Si and Sn. These foreign elements may be incorporated in the crystal structure of the lithium transition metal compound, or may not be incorporated in the crystal structure of the lithium transition metal compound, and may be incorporated alone or in the crystal surface of the particle or crystal grain boundary. May be unevenly distributed.

[Positive electrode for lithium secondary battery]
The positive electrode for a lithium secondary battery is obtained by forming a positive electrode active material layer containing the above-described lithium transition metal-based compound powder for a lithium secondary battery positive electrode material and a binder on a current collector.
The positive electrode active material layer is usually formed by mixing a positive electrode material, a binder, and, if necessary, a conductive material and a thickener, etc. in a dry manner into a sheet and pressing the sheet to the positive electrode current collector. Alternatively, these materials are prepared by dissolving or dispersing these materials in a liquid medium to form a slurry, applying the slurry to a positive electrode current collector, and drying.

  As the material of the positive electrode current collector, a metal material such as aluminum, stainless steel, nickel plating, titanium, and tantalum, and a carbon material such as carbon cloth and carbon paper are usually used. In the case of a metal material, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punched metal, a foamed metal, etc., and in the case of a carbon material, a carbon plate, a carbon thin film, a carbon cylinder And the like. Note that the thin film may be appropriately formed in a mesh shape.

When a thin film is used as the positive electrode current collector, its thickness is arbitrary, but is preferably in the range of usually 1 μm or more and 100 mm or less. If the thickness is smaller than the above range, the strength required as a current collector may be insufficient, while if the thickness is larger than the above range, handleability may be impaired.
The binder used for producing the positive electrode active material layer is not particularly limited, and in the case of a coating method, any material may be used as long as the material is stable to a liquid medium used for producing the electrode. Resin-based polymers such as polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, and nitrocellulose, SBR (styrene / butadiene rubber), NBR (acrylonitrile / butadiene rubber), fluorine rubber, isoprene rubber, butadiene rubber, ethylene Rubbery polymers such as propylene rubber, styrene / butadiene / styrene block copolymers and hydrogenated products thereof, EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / butadiene / ethylene copolymer, Styrene / isoprene styrene bronze Elastomeric polymers such as copolymers and their hydrogenated products, syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer, etc. Ion conductivity of soft resinous polymers, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polymers such as fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, and alkali metal ions (particularly lithium ions) And the like. One of these substances may be used alone, or two or more of them may be used in any combination and in any ratio.

The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more and 80% by mass or less. When the ratio of the binder is too low, the mechanical strength of the positive electrode is insufficient because the positive electrode active material cannot be sufficiently held, and there is a possibility that the battery performance such as cycle characteristics may be deteriorated. It may lead to a decrease in battery capacity and conductivity.
The positive electrode active material layer usually contains a conductive material to increase conductivity. The type is not particularly limited, but specific examples include metal materials such as copper and nickel, graphite (graphite) such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke. And the like. One of these substances may be used alone, or two or more of them may be used in any combination and in any ratio. The proportion of the conductive material in the positive electrode active material layer is usually 0.01% by mass or more and 50% by mass or less. If the proportion of the conductive material is too low, the conductivity may be insufficient, while if it is too high, the battery capacity may be reduced.

  As a liquid medium for forming a slurry, it is possible to dissolve or disperse a lithium transition metal-based compound powder as a positive electrode material, a binder, and a conductive material and a thickener used as necessary. The type of the solvent is not particularly limited, and either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water, alcohols, and the like. Examples of organic solvents include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N , N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran (THF), toluene, acetone, dimethylether, dimethylacetamide, hexamethylphosphalamide, dimethylsulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like. be able to. In particular, when an aqueous solvent is used, a dispersant is added in addition to the thickener, and a slurry is formed using a latex such as SBR. One of these solvents may be used alone, or two or more thereof may be used in any combination and in any ratio.

The content ratio of the lithium transition metal-based compound powder as the positive electrode material in the positive electrode active material layer is usually 10% by mass or more and 99.9% by mass or less. If the ratio of the lithium transition metal-based compound powder in the positive electrode active material layer is too large, the strength of the positive electrode tends to be insufficient, and if it is too small, the capacity may be insufficient.
The thickness of the positive electrode active material layer is usually about 10 to 200 μm.

The electrode density of the positive electrode after pressing is usually 2.2 g / cm ³ or more and 4.2 g / cm ³ or less.
The positive electrode active material layer obtained by coating and drying is preferably compacted by a roller press or the like in order to increase the packing density of the positive electrode active material.
Thus, a positive electrode for a lithium secondary battery can be prepared.

2-3. Separator A separator is usually interposed between the positive electrode and the negative electrode to prevent a short circuit. In this case, the non-aqueous electrolyte of the present invention is usually used by impregnating the separator.
The material and shape of the separator are not particularly limited, and any known materials can be used as long as the effects of the present invention are not significantly impaired. Among them, a resin, a glass fiber, an inorganic material, or the like, which is formed of a material that is stable with respect to the nonaqueous electrolytic solution of the present invention, is used, and a porous sheet or a nonwoven fabric-like material having excellent liquid retention properties is used. Is preferred.

  As a material of the resin and the glass fiber separator, for example, polyolefin such as polyethylene and polypropylene, aromatic polyamide, polytetrafluoroethylene, polyether sulfone, a glass filter and the like can be used. Of these, glass filters and polyolefins are preferred, and polyolefins are more preferred. One of these materials may be used alone, or two or more thereof may be used in any combination and in any ratio.

  The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 50 μm or less, preferably 40 μm or less, and more preferably 30 μm or less. If the separator is thinner than the above range, insulation properties and mechanical strength may be reduced. If the thickness is larger than the above range, not only may the battery performance such as rate characteristics decrease, but also the energy density of the whole non-aqueous electrolyte secondary battery may decrease.

  Further, when a porous material such as a porous sheet or a nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Further, it is usually at most 90%, preferably at most 85%, more preferably at most 75%. If the porosity is less than the above range, the film resistance tends to increase and the rate characteristics tend to deteriorate. On the other hand, if it is too large, the mechanical strength of the separator tends to decrease, and the insulating property tends to decrease.

The average pore diameter of the separator is also arbitrary, but is usually 0.5 μm or less, preferably 0.2 μm or less, and usually 0.05 μm or more. If the average pore diameter exceeds the above range, a short circuit is likely to occur. On the other hand, if the ratio is below the above range, the film resistance may increase and the rate characteristics may decrease.
On the other hand, examples of the inorganic material include oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate. Used.

  As the form, a thin film such as a nonwoven fabric, a woven fabric, or a microporous film is used. In the case of a thin film, those having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the above independent thin film shape, a separator obtained by forming a composite porous layer containing the above inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder may be used. For example, a separator obtained by forming a porous layer on both surfaces of a positive electrode using alumina particles having a 90% particle size of less than 1 μm and a fluororesin as a binder.

  The characteristics of the separator in the nonaqueous electrolyte secondary battery can be grasped by Gurley value. The Gurley value indicates the difficulty in passing air in the thickness direction of the film, and is represented by the number of seconds required for 100 ml of air to pass through the film. Means it is harder to get through. That is, a smaller value means better communication in the thickness direction of the film, and a larger value means poor communication in the thickness direction of the film. The continuity is the degree of connection of the holes in the film thickness direction. If the Gurley value of the separator of the present invention is low, it can be used for various applications. For example, when used as a separator for a non-aqueous lithium secondary battery, a low Gurley value means easy movement of lithium ions, and is preferable because of excellent battery performance. The Gurley value of the separator is optional, but is preferably 10 to 1000 seconds / 100 ml, more preferably 15 to 800 seconds / 100 ml, and still more preferably 20 to 500 seconds / 100 ml. When the Gurley value is 1000 seconds / 100 ml or less, the electric resistance is substantially low, and the separator is preferable.

2-4. Battery design <Electrode group>
The electrode group has a stacked structure in which the positive electrode plate and the negative electrode plate are interposed with the separator interposed therebetween, and a structure in which the positive electrode plate and the negative electrode plate are spirally wound with the separator interposed therebetween. Either may be used. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy) is usually 40% or more, preferably 50% or more, and usually 90% or less, and preferably 80% or less. .

  If the electrode group occupancy is below the above range, the battery capacity will decrease. In addition, when the above range is exceeded, the void space is small, and when the temperature of the battery becomes high, the member expands or the vapor pressure of the liquid component of the electrolyte becomes high, so that the internal pressure rises, and the charge / discharge repetition performance of the battery becomes high. In some cases, a gas release valve that lowers various characteristics such as high temperature and high-temperature storage, and further releases internal pressure to the outside may be operated.

<Outer case>
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the nonaqueous electrolyte used. Specifically, a metal such as a nickel-plated steel plate, stainless steel, aluminum or an aluminum alloy, a magnesium alloy, or a laminated film (laminated film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, a metal of aluminum or an aluminum alloy or a laminated film is suitably used.

  In an outer case using metals, a metal is welded to each other by laser welding, resistance welding, ultrasonic welding to form a sealed hermetic structure, or a caulking structure using the above metals via a resin gasket. Things. An outer case using the above-mentioned laminated film includes a case in which a resin layer is heat-sealed to form a sealed structure. In order to enhance the sealing property, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when a resin layer is heat-sealed through a current collecting terminal to form a hermetically sealed structure, the metal and the resin are joined, so that a resin having a polar group or a polar group introduced as an intervening resin is used. Resins are preferably used.

<Protective element>
As a protection element, a PTC (Positive Temperature Coefficient) thermistor that increases resistance when abnormal heat or excessive current flows, a temperature fuse, and interrupts a current flowing in a circuit due to a sudden increase in battery internal pressure or internal temperature during abnormal heat generation. A valve (current cutoff valve) or the like can be used. It is preferable to select a protection element that does not operate under normal use of a high current, and it is more preferable that the protection element be designed not to cause abnormal heat generation or thermal runaway without the protection element.

(Exterior)
The non-aqueous electrolyte secondary battery of the present invention is generally configured by housing the above-described non-aqueous electrolyte, negative electrode, positive electrode, separator, and the like in an exterior body (exterior case). There is no limitation on this exterior body, and any known one can be adopted as long as the effects of the present invention are not significantly impaired.
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the nonaqueous electrolyte used. Specifically, a metal film such as a nickel-plated steel plate, stainless steel, aluminum or aluminum alloy, magnesium alloy, nickel, titanium or the like, or a laminated film (laminated film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, a metal such as aluminum or an aluminum alloy, or a laminated film is preferably used.

  In the outer case using the above-mentioned metals, laser welding, resistance welding, ultrasonic welding are used to weld the metals together to form a sealed hermetic structure, or a resin gasket and a caulking structure using the above-mentioned metals. To do. An outer case using the above-mentioned laminated film includes a case in which a resin layer is heat-sealed to form a sealed structure. In order to enhance the sealing property, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when a resin layer is heat-sealed through a current collecting terminal to form a hermetically sealed structure, the metal and the resin are joined, so that a resin having a polar group or a polar group introduced as an intervening resin is used. Resins are preferably used.

  The shape of the outer case is also arbitrary, and may be, for example, any of a cylindrical shape, a square shape, a laminate type, a coin shape, and a large size.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

  The abbreviations of the compounds used in this example are shown below.

<Example 1-1, Comparative Example 1-1>
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, 1.2 mol of sufficiently dried LiPF ₆ was added to a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) (volume ratio of 3: 4: 3). / L (as the concentration in the non-aqueous electrolyte) and further contained 2.0% by mass of each of vinylene carbonate (VC) and fluoroethylene carbonate (MFEC) (this is referred to as reference electrolyte 1). . Compounds were added to the entire reference electrolyte solution 1 at the ratios shown in Table 1 below to prepare an electrolyte solution. However, Comparative Example 1-1 is the reference electrolyte 1 itself. The “content (% by mass)” in the table is the concentration in 100% by mass of the non-aqueous electrolyte.

[Preparation of positive electrode]
85% by mass of a lithium-nickel-cobalt-manganese composite oxide (NMC) as a positive electrode active material, 10% by mass of acetylene black as a conductive material, and 5% by mass of polyvinylidene fluoride (PVdF) as a binder, In a methylpyrrolidone solvent, a slurry was prepared by mixing with a disperser. This was uniformly applied on both sides of an aluminum foil having a thickness of 21 μm, dried, and then pressed to obtain a positive electrode.

[Preparation of negative electrode]
50 g of Si fine particles having an average particle diameter of 0.2 μm are dispersed in 2000 g of flaky graphite having an average particle diameter of 35 μm, and charged into a hybridization system (manufactured by Nara Machinery Co., Ltd.). The mixture was retained and treated to obtain a composite of Si and graphite particles. The obtained composite was mixed with coal tar pitch as an organic compound to be a carbonaceous material so that the coverage after firing was 7.5%, and kneaded and dispersed by a biaxial kneader. The obtained dispersion was introduced into a firing furnace and fired at 1000 ° C. for 3 hours in a nitrogen atmosphere. The obtained fired product was further pulverized by a hammer mill and then sieved (45 μm) to prepare a negative electrode active material. The content of the silicon element, the average particle diameter d50, the tap density, and the specific surface area measured by the above measurement method were 2.0% by mass, 20 μm, 1.0 g / cm ³ , and 7.2 m ² / g, respectively. .
In addition to the above-described negative electrode active materials, negative electrode active materials 1 to 3 having various Si contents shown in Table 1 were produced by the same method. The negative electrode active material 1 is the above-mentioned active material itself. The Si content is the mass concentration (% by mass) of the Si fine particles with respect to the total (100% by mass) of the Si fine particles and the graphite particles.

[Manufacture of non-aqueous electrolyte battery (coin type)]
The positive electrode was accommodated in a stainless steel can that also functions as a positive electrode conductor, and the negative electrode was placed thereon via a polypropylene separator impregnated with the nonaqueous electrolyte. The can body and the sealing plate serving also as the negative electrode conductor were caulked and sealed via an insulating gasket to produce a non-aqueous electrolyte secondary battery (coin type).

<Evaluation of non-aqueous electrolyte secondary battery>
[Initial Conditioning]
The non-aqueous electrolyte secondary battery of the coin type cell was charged at a constant current of 0.05 C for 6 hours in a thermostat at 25 ° C., and then discharged to 3.0 V at 0.2 C. CC-CV charging was performed at 0.2 C to 4.1 V. Thereafter, aging was performed at 45 ° C. for 72 hours. Thereafter, the battery was discharged to 3.0 V at 0.2 C to stabilize the electrolytic solution. The difference in charge capacity before and after aging (charge capacity before aging-discharge capacity after aging) was defined as "aging loss".
Table 2 below shows the aging loss normalized by the value of Comparative Example 1-1.

<Example 2-1 and Comparative example 2-1>
[Preparation of positive electrode]
A positive electrode was produced in the same manner as in Example 1-1.

[Preparation of negative electrode]
Aqueous dispersion of sodium carboxymethylcellulose (concentration of sodium carboxymethylcellulose 1% by mass) as a thickener and a binder with respect to the negative electrode active material (graphite: SiO = 95: 5, 90:10; mass ratio), and And an aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber: 50% by mass) was added and mixed with a disperser to form a slurry. This slurry was uniformly applied to one surface of a copper foil having a thickness of 10 μm, dried, and then pressed to obtain a negative electrode. In the negative electrode after drying, the negative electrode active material: sodium carboxymethyl cellulose: styrene butadiene rubber was prepared to have a mass ratio of 97.5: 1.5: 1.

[Preparation of non-aqueous electrolyte]
The reference electrolyte 1 used in Example 1-1 was used. In Example 2-1, the nonaqueous electrolyte was prepared by adding the compound 1 to the entirety of the reference electrolyte 1 at the ratio shown in Table 3 below. Comparative Example 2-1 is the reference electrolyte 1 itself.

[Manufacture of non-aqueous electrolyte battery (coin type)]
The positive electrode was accommodated in a stainless steel can that also functions as a positive electrode conductor, and the negative electrode was placed thereon via a polypropylene separator impregnated with the nonaqueous electrolyte. The can body and the sealing plate serving also as the negative electrode conductor were caulked and sealed via an insulating gasket to produce a non-aqueous electrolyte secondary battery (coin type).

<Evaluation of non-aqueous electrolyte secondary battery>
[Initial Conditioning]
The non-aqueous electrolyte secondary battery of the coin type cell was charged at a constant current of 0.05 C for 6 hours in a thermostat at 25 ° C., and then discharged to 3.0 V at 0.2 C. CC-CV charging was performed at 0.2 C to 4.1 V. Thereafter, aging was performed at 45 ° C. for 72 hours. Thereafter, the battery was discharged to 3.0 V at 0.2 C to stabilize the electrolytic solution. The difference in charge capacity before and after aging (charge capacity before aging-discharge capacity after aging) was defined as "aging loss".
Table 3 below shows the aging loss normalized by the value of Comparative Example 2-1.

<Comparative Examples 3-1 to 3-2>
[Preparation of positive electrode]
A positive electrode was produced in the same manner as in Example 1-1.

[Preparation of negative electrode]
A negative electrode in which the mass concentration of Si fine particles is 0% by mass relative to the total (100% by mass) of Si fine particles and graphite particles.
For the negative electrode active material (natural graphite), an aqueous dispersion of sodium carboxymethylcellulose (concentration of 1% by mass of sodium carboxymethylcellulose) and a water dispersion of styrene-butadiene rubber (styrene- (Butadiene rubber concentration: 50% by mass) was added thereto, and mixed with a disperser to form a slurry. This slurry was uniformly applied to one surface of a copper foil having a thickness of 10 μm, dried, and then pressed to obtain a negative electrode. In the negative electrode after drying, the negative electrode active material: sodium carboxymethylcellulose: styrene-butadiene rubber was prepared to have a mass ratio of 97.5: 1.5: 1.

[Preparation of non-aqueous electrolyte]
The reference electrolyte 1 used in Example 1-1 was used. In Comparative Example 3-1, Compound 1 was added to Reference Electrolyte Solution 1 in the ratio shown in Table 4 below to prepare an electrolyte solution. However, Comparative Example 3-2 is the reference electrolyte 1 itself.

[Manufacture of non-aqueous electrolyte battery (coin type)]
The positive electrode was accommodated in a stainless steel can that also functions as a positive electrode conductor, and the negative electrode was placed thereon via a polypropylene separator impregnated with the nonaqueous electrolyte. The can body and the sealing plate serving also as the negative electrode conductor were caulked and sealed via an insulating gasket to produce a non-aqueous electrolyte secondary battery (coin type).

<Evaluation of non-aqueous electrolyte secondary battery>
[Initial Conditioning]
The non-aqueous electrolyte secondary battery of the coin type cell was charged at a constant current of 0.05 C for 6 hours in a thermostat at 25 ° C., and then discharged to 3.0 V at 0.2 C. CC-CV charging was performed at 0.2 C to 4.1 V. Thereafter, aging was performed at 45 ° C. for 72 hours. Thereafter, the battery was discharged to 3.0 V at 0.2 C to stabilize the electrolytic solution. The difference in charge capacity before and after aging (charge capacity before aging-discharge capacity after aging) was defined as "aging loss".
Table 4 below shows the aging loss normalized by the value of Comparative Example 3-1.

  As is clear from Tables 2 and 3, when the non-aqueous electrolyte containing the specific compound represented by the general formula (A) of the present invention was used (Examples 1-1 and 2-1), the specific compound was It is shown that the aging loss is suppressed more than that of Comparative Example 1-1 not containing. Table 4 shows that when the negative electrode active material was only graphite, aging loss was not suppressed even when the specific compound was contained. Thus, by applying a compound having a structure represented by the general formula (A) to a nonaqueous electrolyte to a negative electrode active material containing metal particles and graphite particles that can be alloyed with Li, aging loss is reduced. It can be seen that it is suppressed.

<Example 4-1 and Comparative Examples 4-1 to 4-2>
[Preparation of positive electrode]
A positive electrode was produced in the same manner as in Example 1.

[Preparation of negative electrode]
A negative electrode was manufactured using the negative electrode active material 1 in the same manner as in Example 1.

[Preparation of non-aqueous electrolyte]
The reference electrolyte 1 used in Example 1 was used. Compounds were added at the ratios shown in Table 5 below to the entire reference electrolyte solution 1 to prepare a non-aqueous electrolyte solution. Comparative Example 4-1 is the reference electrolyte 1 itself.

[Manufacture of non-aqueous electrolyte battery (coin type)]
The positive electrode was accommodated in a stainless steel can that also functions as a positive electrode conductor, and the negative electrode was placed thereon via a polypropylene separator impregnated with the nonaqueous electrolyte. The can body and the sealing plate serving also as the negative electrode conductor were caulked and sealed via an insulating gasket to produce a non-aqueous electrolyte secondary battery (coin type).

<Evaluation of non-aqueous electrolyte secondary battery>
[Initial Conditioning]
The non-aqueous electrolyte secondary battery of the coin type cell was charged at a constant current of 0.05 C for 6 hours in a thermostat at 25 ° C., and then discharged to 3.0 V at 0.2 C. CC-CV charging was performed at 0.2 C to 4.1 V. Thereafter, aging was performed at 45 ° C. for 72 hours. Then, the battery was discharged to 3.0 V at 0.2 C. Furthermore, after performing CC-CV charging (0.05 C cut) of the battery to 4.2 V at 0.2 C, the battery was discharged to 3.0 V at 0.2 C to stabilize the electrolytic solution. The difference in charge capacity before and after aging (charge capacity before aging-discharge capacity after aging) was defined as "aging loss". Then, after CC-CV at 0.2C to 4.2V, the battery was discharged at 0.2C · 1.0C to 3.0V, and the ratio of the obtained 0.2C · 1.0C capacity (1.0C / 0C) was obtained. .2C) was set as “1.0 C / 0.2 C load”.
Table 5 below shows the 1.0 C / 0.2 C load normalized by the value of Comparative Example 4-1.

  As is clear from Table 5, when the nonaqueous electrolytic solution containing the specific compound represented by the general formula (A) of the present invention was used (Example 4-1), Comparative Example 4 containing no specific compound was used. It is shown that the load of 1.0 C / 0.2 C is improved than −1. Further, it is shown that when a compound other than the compound represented by the general formula (A) as in Comparative Example 4-2 is added, the 1.0 C / 0.2 C load is reduced. Thus, by applying a compound having a structure represented by the general formula (A) to a non-aqueous electrolyte to a negative electrode active material containing metal particles and graphite particles that can be alloyed with Li, 1.0 C / It can be seen that the 0.2C load is effectively improved.

<Composition analysis of compound 1>
The ratio of the methyl group substitution position of compound 2 (ortho-form: meta-form: para-form) was calculated by ¹ H-NMR (S = O (CD ₃ ) ₂ , 400 MHz).
Table 6 shows the chemical shifts of the methyl group hydrogen atoms of phosphoric acid-ortho-tricresyl (compound 2), phosphoric acid-meta-tricresyl (compound 3), phosphoric acid-para-tricresyl (compound 4) and compound 1.
The chemical shift of the methyl hydrogen atom at the ortho, meta and para positions in Table 6 was compared with the chemical shift of the hydrogen hydrogen atom of the compound 1 of the compound 1. Was calculated (ortho-form: meta-form: para-form). The ratio of the substitution position of the methyl group of the compound 2 was ortho: meta: para == 0: 65.6: 34.4.

According to the non-aqueous electrolyte solution of the present invention, durability, capacity, resistance, and performance characteristics such as output characteristics have a good overall balance of performance, improve the capacity loss in the aging process at the time of initial conditioning, and improve the balance. Good battery can be provided. Therefore, the non-aqueous electrolyte solution can be suitably used in all fields such as electronic devices using the non-aqueous electrolyte solution secondary battery.
The use of the non-aqueous electrolyte and the non-aqueous electrolyte secondary battery of the present invention is not particularly limited, and the battery can be used for various known applications. Specific examples of applications include laptop computers, e-book players, mobile phones, mobile faxes, mobile copiers, mobile printers, mobile audio players, small video cameras, LCD TVs, handy cleaners, transceivers, electronic organizers, calculators, memories Cards, portable tape recorders, radios, backup power supplies, automobiles, motorcycles, motorbikes, bicycles, lighting equipment, toys, game machines, watches, electric tools, strobes, cameras, and the like can be given.

Claims (13)

A positive electrode capable of occluding and releasing metal ions,
A negative electrode containing a negative electrode active material containing metal particles and graphite particles capable of occluding and releasing metal ions and alloyable with Li,
A non-aqueous electrolyte secondary battery including a non-aqueous solvent and a non-aqueous electrolyte containing an electrolyte dissolved in the non-aqueous solvent,
The non-aqueous electrolyte contains a compound represented by the following general formula (A),
The content of the metal particles capable of being alloyed with Li is 0.1 to 25% by mass relative to the total of the metal particles capable of being alloyed with Li and the graphite particles.
Non-aqueous electrolyte secondary battery characterized by the above-mentioned.

(In the formula (A), R _{1 to} R ₃ each independently represent a hydrocarbon group having 1 to 10 carbon atoms; at least one of R _{1 to} R ₃ is a methyl group ; , C each independently represent an integer of 0 to 5, and a + b + c represents an integer of 1 to 9.) 2. The non-aqueous electrolyte secondary battery according to claim 1 , wherein in the general formula (A), R _{1 to} R ₃ are methyl groups, and a = b = c = 1 or 2. 3. Characterized in that it contains a compound represented by the general formula (A) 2 or more, a non-aqueous electrolyte secondary battery according to claim 1 or 2. When two or more compounds represented by the general formula (A) are contained, the ratio of substitution positions of R _{1 to} R ₃ is the highest in the meta position among the ortho, meta, and para positions. The non-aqueous electrolyte secondary battery according to claim 3 , wherein: The content of the compound represented by the general formula (A) is a non-aqueous or less 0.001 wt% to 10 wt% of the electrolyte solution the total amount of any one of claims 1 to 4 Non-aqueous electrolyte secondary battery. The non-aqueous electrolytic solution further contains at least one compound selected from the group consisting of a cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate having a fluorine atom, a nitrile compound, a cyclic sulfonic acid ester, and a cyclic ether compound. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 5 , wherein: The content of at least one compound selected from the group consisting of the cyclic carbonate having a carbon-carbon unsaturated bond, the cyclic carbonate having a fluorine atom, a nitrile compound, a cyclic sulfonic acid ester, and a cyclic ether compound is a non-aqueous electrolyte. The non-aqueous electrolyte secondary battery according to claim 6 , wherein the content is 0.001% by mass or more and 10% by mass or less based on the total amount of The Li can be alloyed metal particles, Si, Sn, is As, Sb, Al, at least one metal or metal compound selected from the group consisting of Zn and W, any one of claims 1 to 7 The non-aqueous electrolyte secondary battery according to claim 1. The Li can be alloyed metal particles are Si or Si metal oxide, a non-aqueous electrolyte secondary battery according to any one of claims 1 to 8. Negative electrode active material containing said Li can be alloyed metal particles and graphite particles, is a complex and / or a mixture of metal and / or metal compound and graphite particles, any one of claims 1 to 9 The non-aqueous electrolyte secondary battery according to the above item. To the total of the Li can be alloyed metal particles and graphite particles, the content of the Li can be alloyed metal particles are from 0.1 to 20 wt%, any one of claims 1 to 10 The non-aqueous electrolyte secondary battery according to 1. To the total of the Li can be alloyed metal particles and graphite particles, the content of the Li can be alloyed metal particles are from 0.1 to 15 wt%, any one of claims 1 to 11 The non-aqueous electrolyte secondary battery according to 1. To the total of the Li can be alloyed metal particles and graphite particles, the content of the Li can be alloyed metal particles are from 0.1 to 10 wt%, any one of claims 1 to 12 The non-aqueous electrolyte secondary battery according to 1.