JP2014192146A - Nonaqueous secondary battery, and electrolytic solution for nonaqueous secondary battery use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous secondary battery which makes it possible to achieve a high-level overcharge protection based on gas generation from a nonaqueous electrolytic solution, and an extended battery life, and to provide an electrolytic solution for nonaqueous secondary battery use which can be used therefor.SOLUTION: A nonaqueous secondary battery comprises: a particular negative electrode; a particular positive electrode; and an electrolytic solution for nonaqueous secondary battery use. The electrolytic solution for nonaqueous secondary battery use includes a particular aromatic compound expressed by the following formula (1) or (2), an organic solvent, and a particular electrolyte. (In the formula above, Rto R, R, Rand Rrepresent a hydrogen atom or a monovalent substituent group independently of each other, provided that of these groups, the adjacent substituent groups may be bonded or condensed with each other to form a ring; n represents an integer of 1-8; p represents an integer of 1-6; and m represents an integer of 1-3.)

Description

  The present invention relates to a non-aqueous secondary battery and an electrolyte for a non-aqueous secondary battery.

  Lithium secondary batteries are widely used as power sources for portable electronic devices such as mobile phones and notebook computers. With the expansion of applications centering on portable applications, products with lighter and smaller size, higher energy density and higher capacity have been developed. On the other hand, in terms of safety, there is an overcharge phenomenon as an inherent problem. In this case, even if the secondary battery has reached a fully charged state, if the charging is further continued, the electrodes are short-circuited to cause a problem. In particular, a lithium secondary battery using an organic electrolyte solution has been desired to be sufficiently handled from the viewpoint of ensuring safety in use.

  On the other hand, countermeasures are usually taken on the side of the electric device to which the battery is attached. Specifically, a charge control circuit is incorporated, and the supply of electricity is cut off when full charge is reached. However, even though it is extremely rare, the above circuit cannot cope with it, and it is assumed that an overcharged state is reached. Even in such a case, if the non-aqueous electrolyte is improved and overcharge can be suppressed, the reliability can be further improved.

  Several additives to be added to the non-aqueous electrolyte have been proposed for the purpose of suppressing or preventing such problems due to overcharging. Among them, a representative example is biphenyl disclosed in Patent Document 1 below. As a result, it acts on the electrode during overcharging to increase the electrical resistance in the system and suppress the progress of the malfunction. Apart from this, there are some which detect the gas generated at the time of overcharge with a pressure-sensitive valve, and release the internal gas or cut off the current to stop the excessive progress of the malfunction. Cyclohexylbenzene has been proposed as a gas releasing agent applied to the electrolyte of a battery having this pressure-sensitive mechanism (see Patent Document 2 below).

Japanese Patent Application Laid-Open No. 07-302614 Japanese Patent No. 3113652 Japanese Patent Laid-Open No. 10-74537

  In order to more effectively prevent overcharge in a non-aqueous secondary battery having a pressure-sensitive mechanism, the present inventor has searched for an additive that replaces the above-described cyclohexylbenzene. At this time, it has been developed to be compatible with negative electrodes that operate stably in high-potential batteries using lithium titanate (LTO), etc., which have recently been widely used, and to extend the charge life. Was the goal.

  The present invention relates to a non-aqueous secondary battery capable of achieving both high overcharge prevention properties based on gas generation from a non-aqueous electrolyte and a long charge life, and an electrolyte for a non-aqueous secondary battery used therefor The purpose is to provide.

（式中、Ｒ^１１〜Ｒ^１４、Ｒ^ａ、Ｒ^２１、Ｒ^２２はそれぞれ独立に水素原子及び１価の置換基を表す。これらの基は、隣り合う置換基同士が結合もしくは縮合して環を形成していてもよい。ｎは１〜８の整数を表す。ｐは１〜６の整数を表す。ｍは１〜３の整数を表す。）
（負極：第一族又は第二族に属する金属のイオンを挿入放出可能であり、炭素原子（Ｃ）、ケイ素原子（Ｓｉ）、もしくはチタン原子（Ｔｉ）を含む材料を活物質とする）
（正極：第一族又は第二族に属する金属のイオンを挿入放出可能な材料を活物質とする）
（電解質：周期律第一族又は第二族に属する金属のイオンを含む金属塩）
〔２〕特定芳香族化合物を電解液中に１質量％〜４０質量％で含む〔１〕に記載の非水二次電池。
〔３〕負極の活物質がチタン酸リチウムである〔１〕または〔２〕に記載の非水二次電池。
〔４〕Ｒａの少なくとも一つが電子求引性の置換基である〔１〕〜〔３〕のいずれか１項に記載の非水二次電池。
〔５〕正極の活物質がマンガン又は／及びニッケル元素を含む〔１〕〜〔４〕のいずれか１項に記載の非水二次電池。
〔６〕式（１）または（２）におけるｍが１である〔１〕〜〔５〕のいずれか１項に記載の非水二次電池。
〔７〕式（１）または（２）におけるＲ^１４の少なくとも一つ及びＲ^２２の少なくとも一つが水素原子である〔１〕〜〔６〕のいずれか１項に記載の非水二次電池。
〔８〕所定圧力以上になると電流を遮断する機構を有する〔１〕〜〔７〕のいずれか１項に記載の非水二次電池。
〔９〕正極の活物質が下記式（ＭＡ）〜（ＭＣ）のいずれかで表される遷移金属酸化物を含む〔１〕〜〔８〕のいずれか１項に記載の非水二次電池。
Ｌｉ_ａＭ^１Ｏ_ｂ ・・・ （ＭＡ）
Ｌｉ_ｃＭ^２ _２Ｏ_ｄ ・・・ （ＭＢ）
Ｌｉ_ｅＭ^３（ＰＯ_４）_ｆ ・・・ （ＭＣ）
（式中、Ｍ^１およびＭ^２は、それぞれ独立に、Ｃｏ、Ｎｉ、Ｆｅ、Ｍｎ、Ｃｕ、およびＶから選択される１種以上の元素を表す。Ｍ^３は、それぞれ独立に、Ｖ、Ｔｉ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、およびＣｕから選択される１種以上の元素を表す。ただし、Ｍ^１〜Ｍ^３は、その一部が、リチウム以外の周期律表の第１（Ｉａ）族の元素、第２（ＩＩａ）族の元素、Ａｌ、Ｇａ、Ｉｎ、Ｇｅ、Ｓｎ、Ｐｂ、Ｓｂ、Ｂｉ、Ｓｉ、Ｐ、およびＢから選ばれる少なくとも１つにより置換されていてもよい。ａは０〜１．２を表す。ｂは１〜３を表す。ｃは０〜２を表す。ｄは３〜５を表す。ｅは０〜２を表し、ｆは１〜５を表す。）
〔１０〕正極の活物質が、コバルト酸リチウム、マンガン酸リチウム、ニッケル酸リチウム、ニッケルマンガンコバルト酸リチウム、マンガンニッケル酸リチウム、ニッケルコバルトアルミニウム酸リチウム、またはリン酸鉄リチウムである〔１〕〜〔９〕のいずれか１項に記載の非水二次電池。
〔１１〕電解液が直鎖のカーボネート化合物を含有する〔１〕〜〔１０〕のいずれか１項に記載の非水二次電池。
〔１２〕電解液が通常充電時にガスを発生せず、過充電時に有効量のガスを発生する〔１〕〜〔１１〕のいずれか１項に記載の非水二次電池。
〔１３〕下記式（１）または（２）で表される特定芳香族化合物と有機溶媒と下記電解質とを含有する非水二次電池用電解液。

（式中、Ｒ^１１〜Ｒ^１４、Ｒ^ａ、Ｒ^２１、Ｒ^２２はそれぞれ独立に水素原子及び１価の置換基を表す。これらの基は、隣り合う置換基同士が結合もしくは縮合して環を形成していてもよい。ｎは１〜８の整数を表す。ｐは１〜６の整数を表す。ｍは１〜３の整数を表す。）
（電解質：周期律第一族又は第二族に属する金属のイオンを含む金属塩）
〔１４〕特定芳香族化合物が、正極電位で４．５Ｖ（Ｌｉ／Ｌｉ＋基準）以上の充電時に気体を放出する〔１３〕に記載の非水二次電池用電解液。
〔１５〕Ｒａの少なくとも一つが電子求引性の置換基である〔１３〕または〔１４〕に記載の非水二次電池用電解液。
〔１６〕さらに直鎖のカーボネート化合物を含有する〔１３〕〜〔１５〕のいずれか１項に記載の非水二次電池用電解液。
〔１７〕通常充電時にガスを発生せず、過充電時に有効量のガスを発生する〔１３〕〜〔１６〕のいずれか１項に記載の非水二次電池用電解液。
〔１８〕下記式（１）または（２）で表される特定芳香族化合物からなる非水二次電池電解液用添加剤。

（式中、Ｒ^１１〜Ｒ^１４、Ｒ^ａ、Ｒ^２１、Ｒ^２２はそれぞれ独立に水素原子及び１価の置換基を表す。Ｒａの少なくとも一つがハメットのσｐ値が正の値を示す置換基である。これらの基は、隣り合う置換基同士が結合もしくは縮合して環を形成していてもよい。ｎは１〜８の整数を表す。ｐは１〜６の整数を表す。ｍは１〜３の整数を表す。）
〔１９〕過充電試験において、１Ｃにおける充電時の電気量−正極電圧充電カーブの極大値と極小値の差が０．０８Ｖ以上となる特定芳香族化合物を含む〔１〕〜〔１２〕のいずれか１項に記載の非水二次電池。 The above problem has been solved by the following means.
[1] A non-aqueous secondary battery comprising the following negative electrode, the following positive electrode, and an electrolyte for a non-aqueous secondary battery,
A non-aqueous secondary battery in which the electrolyte for a non-aqueous secondary battery contains a specific aromatic compound represented by the following formula (1) or (2), an organic solvent, and the following electrolyte.

(In the formula, R ^{11 to} R ¹⁴ , R ^a , R ²¹ , and R ²² each independently represent a hydrogen atom and a monovalent substituent. These groups are formed by bonding or condensing adjacent substituents. (N represents an integer of 1 to 8. p represents an integer of 1 to 6. m represents an integer of 1 to 3.)
(Negative electrode: Metal ions belonging to Group 1 or Group 2 can be inserted and released, and a material containing carbon atom (C), silicon atom (Si), or titanium atom (Ti) is used as an active material)
(Positive electrode: A material capable of inserting and releasing metal ions belonging to Group 1 or Group 2 is used as an active material)
(Electrolyte: Metal salt containing ions of metals belonging to Group 1 or Group 2 of the periodic rule)
[2] The nonaqueous secondary battery according to [1], wherein the electrolyte contains 1% by mass to 40% by mass of the specific aromatic compound.
[3] The nonaqueous secondary battery according to [1] or [2], wherein the negative electrode active material is lithium titanate.
[4] The nonaqueous secondary battery according to any one of [1] to [3], wherein at least one of Ra is an electron withdrawing substituent.
[5] The nonaqueous secondary battery according to any one of [1] to [4], wherein the active material of the positive electrode contains manganese and / or nickel element.
[6] The nonaqueous secondary battery according to any one of [1] to [5], wherein m in Formula (1) or (2) is 1.
[7] The nonaqueous secondary battery according to any one of [1] to [6], wherein at least one of R ¹⁴ and at least one of R ^{22 in} the formula (1) or (2) is a hydrogen atom.
[8] The nonaqueous secondary battery according to any one of [1] to [7], which has a mechanism for interrupting current when a predetermined pressure is exceeded.
[9] The nonaqueous secondary battery according to any one of [1] to [8], wherein the active material of the positive electrode includes a transition metal oxide represented by any of the following formulas (MA) to (MC) .
Li _a M ¹ O _b (MA)
Li _c M ² ₂ O _d (MB)
Li _e M ³ (PO ₄ ) _f ... (MC)
(In the formula, M ¹ and M ² each independently represent one or more elements selected from Co, Ni, Fe, Mn, Cu, and V. M ³ independently represents V, Ti. , Cr, Mn, Fe, Co, Ni, and Cu represent one or more elements selected from the group consisting of M ^{1 to} M ³ , part of which is the first (Ia) of the periodic table other than lithium ) Group element, Group 2 (IIa) element, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B may be substituted. a represents 0 to 1.2, b represents 1 to 3, c represents 0 to 2, d represents 3 to 5, e represents 0 to 2, and f represents 1 to 5. )
[10] The active material of the positive electrode is lithium cobalt oxide, lithium manganate, lithium nickelate, lithium nickel manganese cobaltate, lithium manganese nickelate, lithium nickel cobaltaluminate, or lithium iron phosphate [1] to [1] 9] The nonaqueous secondary battery according to any one of the above.
[11] The nonaqueous secondary battery according to any one of [1] to [10], wherein the electrolytic solution contains a linear carbonate compound.
[12] The nonaqueous secondary battery according to any one of [1] to [11], wherein the electrolyte does not generate gas during normal charging but generates an effective amount of gas during overcharging.
[13] An electrolyte solution for a non-aqueous secondary battery containing the specific aromatic compound represented by the following formula (1) or (2), an organic solvent, and the following electrolyte.

(In the formula, R ^{11 to} R ¹⁴ , R ^a , R ²¹ , and R ²² each independently represent a hydrogen atom and a monovalent substituent. These groups are formed by bonding or condensing adjacent substituents. (N represents an integer of 1 to 8. p represents an integer of 1 to 6. m represents an integer of 1 to 3.)
(Electrolyte: Metal salt containing ions of metals belonging to Group 1 or Group 2 of the periodic rule)
[14] The electrolyte for a non-aqueous secondary battery according to [13], wherein the specific aromatic compound releases a gas when charged at a positive electrode potential of 4.5 V (Li / Li + reference) or more.
[15] The electrolyte solution for a non-aqueous secondary battery according to [13] or [14], wherein at least one Ra is an electron-attracting substituent.
[16] The electrolyte solution for a non-aqueous secondary battery according to any one of [13] to [15], further containing a linear carbonate compound.
[17] The electrolyte for a non-aqueous secondary battery according to any one of [13] to [16], which does not generate gas during normal charging but generates an effective amount of gas during overcharging.
[18] An additive for a non-aqueous secondary battery electrolyte comprising a specific aromatic compound represented by the following formula (1) or (2).

(Wherein R ^{11 to} R ¹⁴ , R ^a , R ²¹ and R ²² each independently represent a hydrogen atom and a monovalent substituent. At least one of Ra is a substituent having a positive Hammett σp value. In these groups, adjacent substituents may be bonded or condensed to form a ring, n represents an integer of 1 to 8, p represents an integer of 1 to 6, and m represents Represents an integer of 1 to 3)
[19] In any one of [1] to [12], the overcharge test includes a specific aromatic compound in which the difference between the maximum value and the minimum value of the electric charge-positive voltage charging curve during charging at 1C is 0.08 V or more. The non-aqueous secondary battery according to claim 1.

  According to the non-aqueous secondary battery electrolyte and non-aqueous secondary battery of the present invention, it is possible to achieve both a high overcharge prevention property based on gas generation from the non-aqueous electrolyte and a longer life. Moreover, even if it is the conditions using a high potential negative electrode as needed, it adapts suitably and can exhibit the high performance.

It is sectional drawing which shows typically the mechanism of the lithium secondary battery which concerns on preferable embodiment of this invention. It is sectional drawing which shows the specific structure of the lithium secondary battery which concerns on preferable embodiment of this invention. It is a partial cross section side view which shows typically the battery lid body with a pressure-sensitive mechanism which concerns on preferable embodiment of this invention. It is sectional drawing which shows typically the structure of CR2032-type coin battery. It is a charging / discharging curve figure at the time of the overcharge test using a 2032 form coin battery.

  The electrolyte solution for nonaqueous secondary batteries of the present invention contains an electrolyte and the following specific cyclic unsaturated compound or aromatic compound in an organic solvent. Hereinafter, the present invention will be described in detail focusing on this specific cyclic unsaturated compound or aromatic compound.

<Specific aromatic compounds>
The specific aromatic compound used in the present invention has a vinyl group-containing group or an ethynyl group-containing group via a linking group in the molecule. The specific aromatic compound is preferably one represented by the following formula (1) or (2). In the present specification, the specific aromatic compound means a cyclic unsaturated compound (non-benzenoid aromatic compound such as an 8-membered ring).

· ^R 11 ~R ¹⁴
In said formula, R < ¹¹ > -R < ¹⁴ > represents a hydrogen atom and a monovalent substituent each independently. The monovalent substituent is preferably a substituent T described later. Among them, a hydrogen atom, an alkyl group (C1-15 are preferable, C1-12 are more preferable, 1-6 are more preferable, and 1-3 are particularly preferable), and an alkenyl group (C2-12 is preferable). 2-6 are more preferable), an alkoxy group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 and particularly preferably 1 to 3), a halogen atom (iodine atom, bromine atom, chlorine atom, fluorine atom). Preferably, a chlorine atom and a fluorine atom are more preferable, an acyloxy group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 3 carbon atoms), an alkoxycarbonyl group (preferably having 2 to 12 carbon atoms), 2-6 are more preferred), a cyano group, an amino group (preferably having 0 to 6 carbon atoms, more preferably 0 to 3), and a silyl group (preferably having 1 to 12 carbon atoms, preferably 1 to 6). 1 to 3 are particularly preferable), an aryl group (preferably having 6 to 22 carbon atoms, more preferably 6 to 14), or a heteroaryl group (preferably having 1 to 12 carbon atoms and more preferably 2 to 5 carbon atoms). Preferably there is. Those adjacent to each other may be bonded to each other or condensed to form a ring structure.
The substituent may be substituted through a linking group L. Examples of the linking group include a carbonyl group, a carbonyloxy group, an oxy group, a sulfonyl group, a sulfonyloxy group, an imino group, an alkylene group, an alkenylene group, Examples thereof include a sulfide group and a group obtained by combining them.

R ^{11 to} R ¹⁴ are preferably a hydrogen atom, an alkyl group having the carbon number, an alkenyl group having the carbon number, an aryl group having the carbon number, an acyloxy group having the carbon number, a cyano group, or a halogen atom (particularly, Fluorine atom). Particularly preferred are a hydrogen atom, an alkyl group having the carbon number, an alkenyl group having the carbon number, an aryl group having the carbon number, and a fluorine atom.

· ^{R 21, R 22}
R ²¹ and R ²² each independently represent a hydrogen atom and a monovalent substituent. When R ²¹ and R ²² are substituents, they may be connected via a linking group, and the substituents are preferably those defined by R ^{11 to} R ¹⁴ or a combination with the linking group L. Among these, R ²² is preferably the same group as the preferred groups of R ^{11 to} R ¹⁴ . R ²¹ is preferably the alkyl group having the carbon number, the alkenyl group having the carbon number, or the aryl group having the carbon number. When the alkyl group is an aralkyl group, 7 to 15 carbon atoms are preferable, and 7 to 11 are more preferable.

・ R ^a
R ^a represents a hydrogen atom or a substituent. When R ^a is a substituent, it may be connected via a linking group L, and examples of the substituent are preferably those defined by R ^{11 to} R ¹⁴ or a combination of this and the substituent L. Of these, the alkyl group having the carbon number, the alkenyl group having the carbon number, the alkoxy group having the carbon number, and the alkylsulfonyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 3 carbon atoms). , Alkylsulfonyloxy groups (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), halogen atoms, halogenated alkyl groups (preferably having 1 to 12 carbon atoms and more preferably 1 to 6 carbon atoms). 1 to 3 are particularly preferred), an alkoxycarbonyl group (preferably 2 to 6 carbon atoms, more preferably 2 to 4 carbon atoms), an alkoxycarbonyloxy group (preferably 2 to 6 carbon atoms, more preferably 2 to 4 carbon atoms) An amino group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), a carbamoyl group (preferably having 1 to 12 carbon atoms, Still more preferably, from 1 to 3 being particularly preferred) it is preferred. These substituents may further have a substituent T. A plurality of Ras may mean the same or different from each other.

More preferably among the above substituents, at least one of Ra is an electron withdrawing group. Among the electron withdrawing groups, Hammett's σp value is preferably positive, particularly preferably σp value is 0.05 or more, more preferably 0.1 or more.
Here, the substituent constant σp value in Hammett's rule will be described. Hammett's rule is described in 1935 by L.L. in order to quantitatively discuss the effect of substituents on the reaction or equilibrium of benzene derivatives. P. This is a rule of thumb advocated by Hammett, which is widely accepted today. Substituent constants determined by Hammett's rule include σp value and σm value, and these values can be found in many general books. For example, J. et al. A. Dean, “Lange's Handbook of Chemistry”, 12th edition, 1979 (McGraw-Hill), “Areas of Chemistry”, No. 122, 96-103, 1979 (Nankodo), Chem. Rev. 1991, 91, 165-195, Corwin Hansch, A .; LEO and R.M. W. TAFT “A Survey of Hammett Substitute Students and Resonance and Field Parameters” Chem. Rev. 1991, 91, 165-195.

Ｒ^Ｗ１は有機基であり、炭素数１〜１２のアルキル基（好ましくはメチル基、エチル基、プロピル基、イソプロピル基、ブチル基、ｔブチル基、オクチル基）、炭素数６〜１２のアリール基（好ましくはフェニル基、ナフチル基）、炭素数７〜１２のアラルキル基（好ましくはベンジル基、フェネチル基）が好ましい。 The following are mentioned as an example of an electron withdrawing group.

R ^W1 is an organic group, an alkyl group having 1 to 12 carbon atoms (preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tbutyl group, an octyl group), or an aryl group having 6 to 12 carbon atoms. (Preferably a phenyl group or a naphthyl group) or an aralkyl group having 7 to 12 carbon atoms (preferably a benzyl group or a phenethyl group) is preferable.

R ^W2 is an organic group, an alkyl group having 1 to 12 carbon atoms (preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tbutyl group, an octyl group), or an aryl group having 6 to 12 carbon atoms. (Preferably phenyl group, naphthyl group), C 7-12 aralkyl group aralkyl group (preferably benzyl group, phenethyl group), C 2-10 acyl group (preferably acetyl group, pivaloyl group, benzoyl group) , An alkylsulfonyl group having 1 to 12 carbon atoms (preferably a methanesulfonyl group, an ethanesulfonyl group, a trifluoromethanesulfonyl group, a nonafluorobutanesulfonyl group), an arylsulfonyl group having 6 to 12 carbon atoms (preferably a benzenesulfonyl group, Toluenesulfonyl group), alkoxycarbonyl groups having 2 to 10 carbon atoms (preferably Toxicarbonyl group, ethoxycarbonyl group, phenoxycarbonyl group, benzyloxycarbonyl group) are preferred.

When a plurality of R ^W2 are present, they may be bonded to each other to form a ring structure.
R ^W1 and R ^W2 may combine to form a ring structure.
R ^W1 or R ^{W2 of} w1 to w12 may be a divalent or higher valent group, and may be a linking group having two or more structures of w1 to w12. In that case, you may have repeatedly the structure of w1-w12. Examples of the terminal group include Ra examples and w1-w12 examples.

R ^{11 to} R ¹⁴ , R ^a , R ²¹ , and R ²² may form a ring by bonding or condensing adjacent substituents. Examples of the ring formed include a cycloalkyl group, an aryl group, and a heterocyclic group of the following substituent T.

  n represents the integer of 1-8, 1-4 are preferable and 1-3 are more preferable. p represents an integer of 1 to 6. m represents an integer of 1 to 3.

The aromatic nucleus of the compound represented by the formula (1) or (2) preferably has one of the following structures.

The aromatic nucleus may have a substituent T. Among these, preferred groups for ^Ra are mentioned.

前記鎖構造は置換基Ｔを有していてもよい。なかでもＲ^１１〜Ｒ^１４の好ましい基が挙げられる。この置換基は前記連結基Ｌを介して置換していてもよい。 The unsaturated bond-containing substituent substituted on the aromatic nucleus of the compound represented by the formula (1) or (2) preferably has the following chain structure.

The chain structure may have a substituent T. Of these, preferred groups of R ^{11 to} R ¹⁴ are mentioned. This substituent may be substituted through the linking group L.

Specific examples of the specific aromatic compound are shown below, but the present invention is not construed as being limited thereto.

  The specific aromatic compound is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and more preferably 1% by mass or more in the total amount of the electrolyte solution (including the electrolyte). Particularly preferred. On the other hand, the upper limit is preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, and further preferably 15% by mass or less. It is particularly preferable that the content is not more than mass%. By setting the content to be equal to or higher than the lower limit, an effective amount of gas generated during overcharge can be obtained, which is preferable. By setting it to the upper limit value or less, it is preferable without impairing battery performance including cycle characteristics.

The exemplified compound may have an arbitrary substituent T.
Examples of the substituent T include the following.
An alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl A group (preferably an alkenyl group having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), an alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, such as ethynyl, butadiynyl, phenylethynyl, etc.), A cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), an aryl group (preferably an aryl group having 6 to 26 carbon atoms, for example, Phenyl, 1-naphthyl, 4-methoxyphenyl, -Chlorophenyl, 3-methylphenyl, etc.), a heterocyclic group (preferably a heterocyclic group having 2 to 20 carbon atoms, preferably a 5- or 6-membered heterocycle having at least one oxygen atom, sulfur atom, nitrogen atom) A cyclic group is preferable, for example, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, etc., an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, Methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy groups (preferably aryloxy groups having 6 to 26 carbon atoms, such as phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), An alkoxycarbonyl group (preferably an alkoxycarbonyl having 2 to 20 carbon atoms) Nyl groups such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl, etc., amino groups (preferably including amino groups having 0 to 20 carbon atoms, alkylamino groups, arylamino groups, such as amino, N, N-dimethyl Amino, N, N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl groups (preferably sulfonamido groups having 0 to 20 carbon atoms, such as N, N-dimethylsulfamoyl, N-phenylsulfamoyl) Etc.), an acyl group (preferably an acyl group having 1 to 20 carbon atoms, such as acetyl, propionyl, butyryl, benzoyl, etc.), an acyloxy group (preferably an acyloxy group having 1 to 20 carbon atoms, such as acetyloxy, Benzoyloxy, etc.), carbamoyl groups (preferably C 1-20 carbon atoms) Rubamoyl groups such as N, N-dimethylcarbamoyl and N-phenylcarbamoyl), acylamino groups (preferably having 1 to 20 carbon atoms, such as acetylamino and benzoylamino), sulfonamido groups (preferably Is a sulfamoyl group having 0 to 20 carbon atoms, such as methanesulfonamide, benzenesulfonamide, N-methylmethanesulfonamide, N-ethylbenzenesulfonamide, etc., an alkylthio group (preferably an alkylthio having 1 to 20 carbon atoms). Groups such as methylthio, ethylthio, isopropylthio, benzylthio, etc., arylthio groups (preferably arylthio groups having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio ), An alkyl or arylsulfonyl group (preferably an alkyl or arylsulfonyl group having 1 to 20 carbon atoms, such as methylsulfonyl, ethylsulfonyl, benzenesulfonyl, etc.), a hydroxyl group, a cyano group, a halogen atom (for example, a fluorine atom, chlorine) Atoms, bromine atoms, iodine atoms, etc.), more preferably alkyl groups, alkenyl groups, aryl groups, heterocyclic groups, alkoxy groups, aryloxy groups, alkoxycarbonyl groups, amino groups, acylamino groups, hydroxyl groups or halogen atoms. And particularly preferably an alkyl group, an alkenyl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group or a hydroxyl group.
In addition, each of the groups listed as the substituent T may be further substituted with the substituent T described above.

  When the compound or substituent / linking group contains an alkyl group / alkylene group, alkenyl group / alkenylene group, etc., these may be cyclic or chain-like, and may be linear or branched, and substituted as described above. It may be substituted or unsubstituted. Moreover, when an aryl group, a heterocyclic group, etc. are included, they may be monocyclic or condensed and may be similarly substituted or unsubstituted.

(Organic solvent)
The organic solvent used in the present invention is preferably an aprotic organic solvent, and more preferably an aprotic organic solvent having 2 to 10 carbon atoms. The organic solvent is preferably a compound having an ether group, a carbonyl group, an ester group, or a carbonate group. The said compound may have a substituent and the said substituent T is mentioned as the example. In particular, an organic solvent containing a linear carbonate group having 2 to 16 carbon atoms is preferable.

Examples of the organic solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2- Methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate , Methyl isobutyrate, methyl trimethylacetate, ethyl trimethylacetate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyl Examples thereof include tiloxazolidinone, N, N′-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide, and dimethyl sulfoxide phosphoric acid. These may be used alone or in combination of two or more. Among them, at least one member selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate is preferable. Particularly, a high viscosity (high dielectric constant) solvent such as ethylene carbonate or propylene carbonate (for example, ratio A combination of a dielectric constant ε ≧ 30) and a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate (for example, viscosity ≦ 1 mPa · s) is more preferable. This is because the dissociation property of the electrolyte salt and the ion mobility are improved.
A preferred embodiment includes a solvent containing propylene carbonate in an amount of 5% by volume or more, more preferably 10% by volume or more, and still more preferably 15% by volume or more based on the total solvent. As a more preferred embodiment, the cyclic carbonate is contained in an amount of 20 to 80% by volume based on the total solvent, and 25 to 100% by volume of the cyclic carbonate is propylene carbonate. As a more preferred embodiment, a chain carbonate selected from dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate is contained in an amount of 20 to 80% by volume based on the total solvent, and a cyclic carbonate selected from ethylene carbonate or propylene carbonate is contained in an amount of about 20 to 80 volume% is contained, and 25-100 volume% (more preferably 40-100 volume%) of the cyclic carbonate is propylene carbonate. By containing a predetermined amount or more of propylene carbonate, capacity deterioration can be reduced even in a large current discharge at a low temperature.
However, the organic solvent used in the present invention is not limited to the above examples.

(Functional additives)
The electrolytic solution of the present invention preferably contains various functional additives. Examples of the function manifested by this additive include improved flame retardancy, improved cycle characteristics, and improved capacity characteristics. Examples of functional additives that are preferably applied to the electrolyte of the present invention are shown below.

<Aromatic compound (A)>
Examples of aromatic compounds include biphenyl compounds and alkyl-substituted benzene compounds. The biphenyl compound has a partial structure in which two benzene rings are bonded by a single bond, and the benzene ring may have a substituent, and preferred substituents are alkyl groups having 1 to 4 carbon atoms (for example, , Methyl, ethyl, propyl, t-butyl and the like) and aryl groups having 6 to 10 carbon atoms (for example, phenyl, naphthyl and the like).
Specific examples of the biphenyl compound include biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, 4-methylbiphenyl, 4-ethylbiphenyl, and 4-tert-butylbiphenyl.
The alkyl-substituted benzene compound is preferably a benzene compound substituted with an alkyl group having 1 to 10 carbon atoms, and specific examples include cyclohexylbenzene, t-amylbenzene, and t-butylbenzene.

<Halogen-containing compound (B)>
The halogen atom contained in the halogen-containing compound is preferably a fluorine atom, a chlorine atom, or a bromine atom, and more preferably a fluorine atom. The number of halogen atoms is preferably 1 to 6, more preferably 1 to 3. The halogen-containing compound is preferably a carbonate compound substituted with a fluorine atom, a polyether compound having a fluorine atom, or a fluorine-substituted aromatic compound.
The halogen-substituted carbonate compound may be either linear or cyclic. From the viewpoint of ion conductivity, a cyclic carbonate compound having a high coordination property of an electrolyte salt (for example, lithium ion) is preferable, and a 5-membered cyclic carbonate compound is particularly preferable. preferable.
Preferred specific examples of the halogen-substituted carbonate compound are shown below. Among these, compounds of Bex1 to Bex4 are particularly preferable, and Bex1 is particularly preferable.

<Polymerizable compound (C)> ... excluding the specific aromatic compound As the polymerizable compound, a compound having a carbon-carbon double bond is preferable, and a carbonate compound having a double bond such as vinylene carbonate or vinylethylene carbonate. , An acrylate group, a methacrylate group, a cyanoacrylate group, a compound having a group selected from an αCF ₃ acrylate group, and a compound having a styryl group are preferred, and a carbonate compound having a double bond, or two or more polymerizable groups in the molecule. The compound having is more preferable.

<Phosphorus-containing compound (D)>
As a phosphorus containing compound, a phosphate ester compound and a phosphazene compound are preferable. Preferable examples of the phosphate ester compound include trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tribenzyl phosphate, and tristrifluoroethyl phosphate. As the phosphazene compound, a compound represented by the following formula (D2) or (D3) is preferable.

In formula, R ^<D4 > -R <^D11> represents a monovalent substituent. Among the monovalent substituents, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a halogen atom such as fluorine, chlorine or bromine is preferable. At least one of the substituents of R ^{D4 to} R ^D11 is preferably a fluorine atom, and more preferably a substituent composed of an alkoxy group, an amino group, or a fluorine atom.

<Sulfur-containing compound (E)>
As the sulfur-containing compound, compounds having —SO ₂ —, —SO ₃ —, and —OS (═O) O— bonds are preferable, and cyclic sulfur-containing compounds such as propane sultone, propene sultone, and ethylene sulfite, and sulfonic acid Esters are preferred.

  As the sulfur-containing cyclic compound, compounds represented by the following formulas (E1) and (E2) are preferable.

In the formula, X ¹ and X ² each independently represent —O— or —C (Ra) (Rb) —. Here, Ra and Rb each independently represent a hydrogen atom or a substituent. The substituent is preferably an alkyl group having 1 to 8 carbon atoms, a fluorine atom, or an aryl group having 6 to 12 carbon atoms. α represents an atomic group necessary for forming a 5- to 6-membered ring. The skeleton of α may contain a sulfur atom, an oxygen atom, etc. in addition to a carbon atom. α may be substituted, and examples of the substituent include a substituent T, preferably an alkyl group, a fluorine atom, and an aryl group.

<Silicon-containing compound (F)>
As the silicon-containing compound, a compound represented by the following formula (F1) or (F2) is preferable.

R ^F1 represents an alkyl group, an alkenyl group, an acyl group, an acyloxy group, or an alkoxycarbonyl group.
R ^F2 represents an alkyl group, an alkenyl group, an alkynyl group, or an alkoxy group.
A plurality of R ^F1 and R ^{F2 in} one formula may be different or the same.

<Nitrile compound (G)>
As the nitrile compound, a compound represented by the following formula (G) is preferable.

In the formula, R ^{G1 to} R ^G3 each independently represent a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group, a carbamoyl group, a sulfonyl group, or a phosphonyl group. The preferable examples of each substituent can refer to the example of the substituent T, and among them, a compound in which any one of R ^{G1 to} R ^G3 has a plurality of nitrile groups containing a cyano group is preferable.

* Ng represents the integer of 1-8.

  Specific examples of the compound represented by the formula (G) include acetonitrile, propionitrile, isobutyronitrile, succinonitrile, malononitrile, glutaronitrile, adiponitrile, 2-methylglutanonitrile, hexanetricarbonitrile, propane. Tetracarbonitrile and the like are preferable. Particularly preferred are succinonitrile, malononitrile, glutaronitrile, adiponitrile, 2-methylglutanonitrile, hexanetricarbonitrile, and propanetetracarbonitrile.

<Metal complex compound (H)>
As the metal complex compound, a transition metal complex or a rare earth complex is preferable. Especially, the complex represented by either of following formula (H-1)-(H-3) is preferable.

In the formula, X ^H and Y ^H are a methyl group, an n-butyl group, a bis (trimethylsilyl) amino group, and a thioisocyanate group, respectively, and X ^H and Y ^H are condensed to form a cyclic alkenyl group (butadiene group). (Positional metallacycle) may be formed. In the formula, ^MH represents a transition element or a rare earth element. Specifically, ^MH is preferably Fe, Ru, Cr, V, Ta, Mo, Ti, Zr, Hf, Y, La, Ce, Sw, Nd, Lu, Er, Yb, and Gd. m ^H and n ^H are integers satisfying 0 ≦ m ^H + n ^H ≦ 3. n ^H + m ^H is preferably 1 or more. When n ^H and m ^H are 2 or more, the 2 or more groups defined therein may be different from each other.

The metal complex compound is also preferably a compound having a partial structure represented by the following formula (H-4).

^MH- (NR ^{<1 >} R ^{< 2H>} ) qH ... Formula (H-4)

In the formula, ^MH represents a transition element or a rare earth element and is synonymous with formulas (H-1) to (H-3).

R ^1H and R ^2H are hydrogen, an alkyl group (preferably having 1 to 6 carbon atoms), an alkenyl group (preferably having 2 to 6 carbon atoms), an alkynyl group (preferably having 2 to 6 carbon atoms), an aryl group (preferably having carbon numbers). Represents a heteroaryl group (preferably having a carbon number of 3 to 6), an alkylsilyl group (preferably having a carbon number of 1 to 6), or a halogen. R ^1H and R ^2H may be linked to each other. R ^1H and R ^2H may each be connected to form a ring. Preferable examples of R ^1H and R ^2H include examples of the substituent T described later. Of these, a methyl group, an ethyl group, and a trimethylsilyl group are preferable.
q ^H represents an integer of 1 to 4, and an integer of 2 to 4 is preferable. More preferably, it is 2 or 4. When q ^H is 2 or more, where a plurality of groups as defined may be the same or different from each other.

The metal complex compound is also preferably a compound represented by any of the following formulas.

・ M ^h
The central metal ^M h is, Ti, Zr, ZrO, Hf , V, Cr, Fe, Ce is particularly preferred, Ti, Zr, Hf, V , Cr is the most preferred.

・ R ^3h , R ^5h , R ^{7h to} R ^10h
These represent substituents. Among these, an alkyl group, an alkoxy group, an aryl group, an alkenyl group, and a halogen atom are preferable, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and 2 carbon atoms. -6 alkenyl groups are more preferred, preferably methyl, ethyl, propyl, isopropyl, isobutyl, t-butyl, perfluoromethyl, methoxy, phenyl, ethenyl.

・ R ^33h , R ^55h
R ^33h and R ^55h represent a hydrogen atom or a substituent of R ^3h .

・ Y ^h
Y ^h is preferably an alkyl group or a bis (trialkylsilyl) amino group having 1 to 6 carbon atoms, more preferably a methyl group or a bis (trimethylsilyl) amino group.

^{· L h, m h, o} h
l ^{h, m h, o h} represents an integer of 0 to 3, preferably an integer of 0 to 2. When l ^h , m ^h , and o ^h are 2 or more, the plurality of structural portions defined therein may be the same as or different from each other.

・ L ^h
L ^h is preferably an alkylene group or an arylene group, more preferably a cycloalkylene group having 3 to 6 carbon atoms or an arylene group having 6 to 14 carbon atoms, and further preferably cyclohexylene or phenylene.

<Imide compound (I)>
As the imide compound, a sulfonimide compound having a perfluoro group is preferable from the viewpoint of oxidation resistance, and specifically, a perfluorosulfoimide lithium compound may be mentioned.
Specific examples of the imide compound include the following structures, and Cex1 and Cex2 are more preferable.

  In addition to the above, the electrolytic solution of the present invention may contain at least one selected from a negative electrode film forming agent, a flame retardant, an overcharge preventing agent and the like. The content ratio of these functional additives in the nonaqueous electrolytic solution is not particularly limited, but is preferably 0.001% by mass to 10% by mass with respect to the entire nonaqueous electrolytic solution (including the electrolyte). By adding these compounds, it is possible to suppress rupture / ignition of the battery at the time of abnormality due to overcharge, and to improve the capacity maintenance characteristic and cycle characteristic after high-temperature storage.

(Electrolytes)
The electrolyte used in the electrolytic solution of the present invention is a salt of a metal ion belonging to Group 1 or Group 2 of the periodic table. The material is appropriately selected depending on the intended use of the electrolytic solution. For example, lithium salt, potassium salt, sodium salt, calcium salt, magnesium salt and the like can be mentioned. When used in a secondary battery or the like, lithium salt is preferable from the viewpoint of output. When the electrolytic solution of the present invention is used as an electrolyte of a non-aqueous electrolytic solution for a lithium secondary battery, a lithium salt may be selected as a metal ion salt. The lithium salt is not particularly limited as long as it is a lithium salt usually used for an electrolyte of a non-aqueous electrolyte solution for a lithium secondary battery. For example, those described below are preferable.

(L-1) Inorganic lithium salts: inorganic fluoride salts such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ ; perhalogenates such as LiClO ₄ , LiBrO ₄ , LiIO ₄ ; inorganic chloride salts such as LiAlCl ₄ etc.

(L-2) Fluorine-containing organic lithium salt: Perfluoroalkane sulfonate such as LiCF ₃ SO ₃ ; LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , Perfluoroalkanesulfonylimide salts such as LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ); perfluoroalkanesulfonylmethide salts such as LiC (CF ₃ SO ₂ ) ₃ ; Li [PF ₅ (CF ₂ CF ₂ CF ₃ )], Li [PF ₄ (CF ₂ CF ₂ CF ₃ ) ₂ ], Li [PF ₃ (CF ₂ CF ₂ CF ₃ ) ₃ ], Li [PF ₅ (CF ₂ CF ₂ CF ₂ CF _{3 )], Li [PF 4 (} CF 2 CF 2 CF 2 CF 3) 2], Li [PF 3 (CF 2 CF 2 CF 2 CF 3) 3] fluoroalkyl fluoride such as potash Acid salts, and the like.

(L-3) Oxalatoborate salt: lithium bis (oxalato) borate, lithium difluorooxalatoborate and the like.
Among these, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , Li (Rf ¹ SO ₃ ), LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ), preferably LiPF ₆ , LiBF ₄ , LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ) More preferred are imide salts. Here, Rf ¹ and Rf ² each represent a perfluoroalkyl group.
In addition, the electrolyte used for electrolyte solution may be used individually by 1 type, or may combine 2 or more types arbitrarily.
The content of the electrolyte (metal ions belonging to Group 1 or Group 2 of the periodic table or metal salts thereof) in the electrolytic solution is added in an amount so as to have a preferable salt concentration described in the electrolytic solution preparation method below. . The salt concentration is appropriately selected depending on the purpose of use of the electrolytic solution, but is generally 10% by mass to 50% by mass, more preferably 15% by mass to 30% by mass, based on the total mass of the electrolytic solution. In addition, when evaluating as an ion density | concentration, what is necessary is just to calculate by salt conversion with the metal applied suitably.

[Method for preparing electrolytic solution]
The electrolyte solution for a non-aqueous secondary battery of the present invention is prepared by a conventional method by dissolving each of the above components in the non-aqueous electrolyte solvent, including an example in which a lithium salt is used as a metal ion salt.

In the present invention, “non-water” means that water is not substantially contained, and a trace amount of water may be contained as long as the effects of the invention are not hindered. In view of obtaining good characteristics, the water content is preferably 200 ppm or less, more preferably 100 ppm or less, and even more preferably 20 ppm or less. Although there is no lower limit in particular, it is practical that it is 1 ppm or more considering inevitable mixing. The viscosity of the electrolytic solution of the present invention is not particularly limited, but is preferably 10 to 0.1 mPa · s, more preferably 5 to 0.5 mPa · s at 25 ° C.
In the present invention, the viscosity of the electrolytic solution is based on the value measured by the following measuring method unless otherwise specified.

<Measurement method of viscosity>
The viscosity is a value measured by the following method. 1 mL of a sample is put into a rheometer (CLS 500) and measured using a Steel Cone (both manufactured by TA Instruments) having a diameter of 4 cm / 2 °. The sample is kept warm in advance until the temperature becomes constant at the measurement start temperature, and the measurement starts thereafter. The measurement temperature is 25 ° C.

[Secondary battery]
In this invention, it is preferable to set it as the non-aqueous secondary battery containing the said non-aqueous electrolyte. As a preferred embodiment, a lithium ion secondary battery will be described with reference to FIG. 1 schematically showing the mechanism. The lithium ion secondary battery 10 of this embodiment includes the electrolyte solution 5 for a non-aqueous secondary battery of the present invention and a positive electrode C capable of inserting and releasing lithium ions (a positive electrode current collector 1 and a positive electrode active material layer 2). And a negative electrode A (negative electrode current collector 3, negative electrode active material layer 4) capable of inserting and releasing lithium ions or dissolving and depositing lithium ions. In addition to these essential members, considering the purpose of use of the battery, the shape of the potential, etc., a separator 9 disposed between the positive electrode and the negative electrode, a current collecting terminal (not shown), an outer case, etc. (Not shown). If necessary, a protective element may be attached to at least one of the inside of the battery and the outside of the battery. By adopting such a structure, lithium ion transfer a and b occurs in the electrolytic solution 5, charging α and discharging β can be performed, and operation or power storage is performed via the operation mechanism 6 via the circuit wiring 7. It can be performed. Hereinafter, the configuration of the lithium secondary battery which is a preferred embodiment of the present invention will be described in more detail.

(Battery shape)
The battery shape to which the lithium secondary battery of the present embodiment is applied is not particularly limited, and examples thereof include a bottomed cylindrical shape, a bottomed square shape, a thin shape, a sheet shape, and a paper shape. Any of these may be used. Further, it may be of a different shape such as a horseshoe shape or a comb shape considering the shape of the system or device to be incorporated. Among them, from the viewpoint of efficiently releasing the heat inside the battery to the outside, a square shape such as a bottomed square shape or a thin shape having at least one surface that is relatively flat and has a large area is preferable.

  In a battery having a bottomed cylindrical shape, since the outer surface area with respect to the power generating element to be filled becomes small, it is preferable to design so that Joule heat generated by the internal resistance at the time of charging and discharging efficiently escapes to the outside. Moreover, it is preferable to design so that the filling ratio of the substance having high thermal conductivity is increased and the temperature distribution inside is reduced. FIG. 2 is an example of a bottomed cylindrical lithium secondary battery 100. This battery is a bottomed cylindrical lithium secondary battery 100 in which a positive electrode sheet 14 and a negative electrode sheet 16 overlapped with a separator 12 are wound and accommodated in an outer can 18.

In the bottomed square shape, the ratio of the area S of the largest surface (the product of the width and height of the outer dimensions excluding the terminal portion, unit cm ² ) to the thickness T (unit cm) of the battery outer shape The 2S / T value is preferably 100 or more, and more preferably 200 or more. By increasing the maximum surface, it is possible to improve characteristics such as cycle performance and high-temperature storage even for high-power and large-capacity batteries, and increase the heat dissipation efficiency during abnormal heat generation. It is possible to suppress a dangerous state of “rupture”.

(Members constituting the battery)
The lithium secondary battery according to the present embodiment is configured to include the electrolytic solution 5, the positive electrode and negative electrode electrode mixtures C and A, and the separator basic member 9, based on FIG. 1. Hereinafter, each of these members will be described.

(Electrode mixture)
The electrode mixture is obtained by applying a dispersion of an active material and a conductive agent, a binder, a filler, etc. on a current collector (electrode substrate). In a lithium battery, the active material is a positive electrode active material. It is preferable to use a negative electrode mixture in which the positive electrode mixture and the active material are a negative electrode active material. Next, each component in the dispersion (electrode composition) constituting the electrode mixture will be described.

-Positive electrode active material It is preferable to use a transition metal oxide for the positive electrode active material, and in particular, it has a transition element M ^a (one or more elements selected from Co, Ni, Fe, Mn, Cu, V). Is preferred. Further, mixed element M ^b (elements of the first (Ia) group of the metal periodic table other than lithium, elements of the second (IIa) group, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si , P, B, etc.) may be mixed. This, for example, as a transition metal oxide, the following formula (MA) ~ certain transition metal oxides including those represented by any one of (MC), or _V 2 _O 5 as other transition metal oxides, MnO _2, etc. Is mentioned. As the positive electrode active material, a particulate positive electrode active material may be used. Specifically, a transition metal oxide capable of reversibly inserting and releasing lithium ions can be used, but the specific transition metal oxide is preferably used.

The transition metal oxides, oxides containing the transition element M ^a is preferably exemplified. At this time, a mixed element M ^b (preferably Al) or the like may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the amount of the transition metal. That the molar ratio of li / ^{M a} is synthesized by mixing so that 0.3 to 2.2 is more preferable.

[Transition metal oxide represented by formula (MA) (layered rock salt structure)]
As the lithium-containing transition metal oxide, those represented by the following formula are preferable.
Li _a M ¹ O _b (MA)

Wherein, ^{M 1} is the same meaning as defined above Ma. a represents 0 to 1.2 (preferably 0.2 to 1.2), and preferably 0.6 to 1.1. b represents 1-3 and is preferably 2. A part of M ¹ may be substituted with the mixed element M ^b . The transition metal oxide represented by the formula (MA) typically has a layered rock salt structure.

The transition metal oxide is more preferably one represented by the following formulas.
_{(MA-1) Li g CoO} k
_{(MA-2) Li g NiO} k
_{(MA-3) Li g MnO} k
_{(MA-4) Li g Co} j Ni 1-j O k
_{(MA-5) Li g Ni} j Mn 1-j O k
_{(MA-6) Li g Co} j Ni i Al 1-j-i O k
_{(MA-7) Li g Co} j Ni i Mn 1-j-i O k

Here, g has the same meaning as a. j represents 0.1 to 0.9. i represents 0 to 1; However, 1-j-i is 0 or more. k has the same meaning as b. Specific examples of the transition metal compound include LiCoO ₂ (lithium cobaltate [LCO]), LiNi ₂ O ₂ (lithium nickelate) LiNi _0.85 Co _0.01 Al _0.05 O ₂ (nickel cobalt aluminum acid Lithium [NCA]), LiNi _0.33 Co _0.33 Mn _0.33 O ₂ (lithium nickel manganese cobaltate [NMC]), LiNi _0.5 Mn _0.5 O ₂ (lithium manganese nickelate).

The transition metal oxide represented by the formula (MA) partially overlaps, but when represented by changing the notation, those represented by the following are also preferable examples.
_{(I) Li g Ni x Mn} y Co z O 2 (x> 0.2, y> 0.2, z ≧ 0, x + y + z = 1)
Representative:
_{Li g Ni 1/3 Mn 1/3 Co 1/3} O 2
Li _g Ni _1/2 Mn _1/2 O _{2
(Ii) Li g Ni x Co} y Al z O 2 (x> 0.7, y>0.1,0.1>z> 0.05, x + y + z = 1)
Representative:
_{Li g Ni 0.8 Co 0.15 Al 0.05} O 2

[Transition metal oxide represented by formula (MB) (spinel structure)]
Among the lithium-containing transition metal oxides, those represented by the following formula (MB) are also preferable.
Li _c M ² ₂ O _d (MB)

Wherein, ^{M 2} are as defined above Ma. c represents 0 to 2 (preferably 0.2 to 2), and preferably 0.6 to 1.5. d represents 3 to 5 and is preferably 4.

The transition metal oxide represented by the formula (MB) is more preferably one represented by the following formulas.
_{(MB-1) Li m Mn} 2 O n
_{(MB-2) Li m Mn} p Al 2-p O n
_{(MB-3) Li m Mn} p Ni 2-p O n

m is synonymous with c. n is synonymous with d. p represents 0-2. Specific examples of the transition metal compound are LiMn ₂ O ₄ and LiMn _1.5 Ni _0.5 O ₄ .

Preferred examples of the transition metal oxide represented by the formula (MB) include those represented by the following.
(A) LiCoMnO ₄
(B) Li ₂ FeMn ₃ O ₈
(C) Li ₂ CuMn ₃ O ₈
(D) Li ₂ CrMn ₃ O ₈
(E) Li ₂ NiMn ₃ O ₈
Of these, an electrode containing Ni is more preferable from the viewpoint of high capacity and high output.

[Transition metal oxide represented by formula (MC)]
As the lithium-containing transition metal oxide, it is also preferable to use a lithium-containing transition metal phosphor oxide, and among them, one represented by the following formula (MC) is also preferable.
Li _e M ³ (PO ₄ ) _f ... (MC)

  In formula, e represents 0-2 (0.2-2 are preferable), and it is preferable that it is 0.5-1.5. f represents 1 to 5 and is preferably 0.5 to 2.

The M ³ represents one or more elements selected from V, Ti, Cr, Mn, Fe, Co, Ni, and Cu. Wherein ^{M 3} represents, in addition to the mixing element ^{M b} above, Ti, Cr, Zn, Zr, may be substituted by other metals such as Nb. Specific examples include, for example, olivine-type iron phosphates such as LiFePO ₄ and Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and Li _3. Monoclinic Nasicon type vanadium phosphate salts such as V ₂ (PO ₄ ) ₃ (lithium vanadium phosphate) can be mentioned.
The a, c, g, m, and e values representing the composition of Li are values that change due to charge and discharge, and are typically evaluated as values in a stable state when Li is contained. In the above formulas (a) to (e), the composition of Li is shown as a specific value, but this also varies depending on the operation of the battery.

In the present invention, the positive electrode active material is preferably a material that can maintain normal use at a positive electrode potential (Li / Li ⁺ standard) of 3.5 V or higher, more preferably 3.8 V or higher, and more preferably 4 V or higher. More preferably, it is more preferably 4.25V or more, and further preferably 4.3V or more. Although there is no upper limit in particular, it is practical that it is 5V or less. By setting it as the above range, cycle characteristics and high rate discharge characteristics can be improved.
Here, being able to maintain normal use means that even when charging is performed at that voltage, the electrode material does not deteriorate and cannot be used, and this potential is also referred to as a normal usable potential.
The positive electrode potential during charging is (positive electrode potential) = (negative electrode potential) + (battery voltage). When lithium titanate is used as the negative electrode, the negative electrode potential is 1.55V. When graphite, graphite / silicon, or tin is used as the negative electrode, the negative electrode potential is set to 0.1V. The battery voltage is observed during charging and the positive electrode potential is calculated.

In the non-aqueous secondary battery of the present invention, the average particle size of the positive electrode active material used is not particularly limited, but is preferably 0.1 μm to 50 μm. No particular limitation is imposed on the specific surface area, preferably from 0.01m ² / g~50m ² / g by the BET method. Further, the pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.

  In order to make the positive electrode active substance have a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a vibration ball mill, a vibration mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. The positive electrode active material obtained by the firing method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

  Although the compounding quantity of a positive electrode active material is not specifically limited, It is preferable that it is 60-98 mass% in 100 mass% of solid components in the dispersion (mixture) for comprising an active material layer. More preferably, it is 70-95 mass%.

・ Negative electrode active material As the negative electrode active material, a material that can insert and release ions of metals belonging to the first group or the second group and contains carbon atoms (C), silicon atoms (Si), or titanium atoms (Ti). Is used. Specific examples include carbonaceous materials, metal oxides such as silicon oxide, metal composite oxides, lithium alloys such as lithium alone and lithium aluminum alloys, and metals such as Si that can form alloys with lithium. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios. Of these, carbonaceous materials or lithium composite oxides are preferably used from the viewpoint of safety. Further, the metal composite oxide is not particularly limited as long as it can occlude and release lithium, but it preferably contains titanium and / or lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics. .

  The carbonaceous material used as the negative electrode active material is a material substantially made of carbon. Examples thereof include carbonaceous materials obtained by baking various synthetic resins such as artificial pitches such as petroleum pitch, natural graphite, and vapor-grown graphite, and PAN-based resins and furfuryl alcohol resins. Furthermore, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA-based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, mesophase micro Examples thereof include spheres, graphite whiskers, and flat graphite.

  These carbonaceous materials can be divided into non-graphitizable carbon materials and graphite-based carbon materials depending on the degree of graphitization. Further, the carbonaceous material preferably has the surface spacing, density, and crystallite size described in JP-A-62-222066, JP-A-2-6856, and 3-45473. The carbonaceous material does not need to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, or the like is used. You can also.

  In the nonaqueous secondary battery of the present invention, the average particle size of the negative electrode active material used is preferably 0.1 μm to 60 μm. To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill or a sieve is preferably used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.

  The chemical formula of the compound obtained by the firing method can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method and a mass difference between powders before and after firing as a simple method.

  In the present invention, the negative electrode active material that can be used in combination with the amorphous oxide negative electrode active material centered on Si and Ge includes a carbon material capable of inserting and extracting lithium ions or lithium metal, lithium, and a lithium alloy. Preferred examples include metals that can be alloyed with lithium. In this invention, the effect | action by using specific negative electrode active materials, such as LTO, for the negative electrode of a battery is estimated as follows. That is, in the conventional battery using a specific electrode (tin), the charge / discharge efficiency deteriorates due to Li generated by the reduction reaction or metal interaction, but this point is considered to be improved. On the other hand, as a mechanism of gas generation from the specific aromatic compound, a hydrogen elimination reaction by an intramolecular cyclization reaction can be considered. It is understood that the compound of the present invention has an unsaturated bond via a linking group in the molecule and promotes this intramolecular cyclization. In this respect, the negative electrode using tin is considered to be less effective because an additive having an active unsaturated site reacts and disappears due to generation of lithium dendrite.

The electrolyte solution of the present invention is preferably combined with a high potential negative electrode (preferably lithium-titanium oxide, a potential of 1.55 V vs. Li metal) and a low potential negative electrode (preferably a carbon material, potential of about 0.1 V vs. Li). Excellent properties are exhibited in any combination with (metal). Metal or metal oxide negative electrode capable of forming an alloy with lithium, which is being developed for higher capacity (preferably Si, Si oxide, Si / Si oxide, and composite of these metal or metal oxide and carbon material) It can be preferably used also in a battery having a negative electrode as a body.
Especially, as a negative electrode active material, it is preferable to use what a normal operating potential becomes 0-2V (preferably 0.1-1.6V) with a counter metal lithium. The operating potential is a value measured by the measurement method described for the positive electrode active material, that is, electrochemical measurement (cyclic voltammetry) using the triode cell.

The negative electrode active material used in the nonaqueous secondary battery of the present invention preferably contains a titanium atom. More specifically, lithium titanate (preferably Li ₄ Ti ₅ O ₁₂ ), H ₂ Ti ₁₂ O ₂₅ , titanium oxide (preferably TiO ₂ ), particularly preferably Li ₄ Ti ₅ O ₁₂ is occluded and released of lithium ions. Since the volume fluctuation at the time is small, it is preferable in that the deterioration of the electrode is suppressed and the life of the lithium ion secondary battery can be improved.

-Conductive material As the conductive material, any electronic conductive material that does not cause a chemical change in the configured secondary battery may be used, and any known conductive material may be used. Usually, natural graphite (scale-like graphite, scale-like graphite, earth-like graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber and metal powder (copper, nickel, aluminum, silver (Japanese Patent Laid-Open No. Sho 63- 10148,554)), metal fibers or polyphenylene derivatives (described in JP-A-59-20971) can be contained as a single type or a mixture thereof. Among these, the combined use of graphite and acetylene black is particularly preferable. As addition amount of the said electrically conductive agent, 1-50 mass% is preferable and 2-30 mass% is more preferable. In the case of carbon or graphite, 2 to 15% by mass is particularly preferable.

-Binders Examples of binders include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Among them, for example, starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose. , Sodium alginate, polyacrylic acid, sodium polyacrylate, polyvinyl phenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylonitrile, polyacrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer, etc. Polymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinyl Redene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, etc. ) (Meth) acrylic ester copolymer containing acrylic ester, (meth) acrylic ester-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate, styrene-butadiene copolymer , Acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluororubber, polyethylene oxide, polyester polyurethane resin, polyether polyurethane resin, polycarbonate Polyurethane resins, polyester resins, phenolic resins, emulsion (latex) or a suspension such as an epoxy resin is preferable, a latex of polyacrylate, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride is more preferable.

  A binder can be used individually by 1 type or in mixture of 2 or more types. When the amount of the binder added is small, the holding power and cohesive force of the electrode mixture are weakened. If the amount is too large, the electrode volume increases and the capacity per electrode unit volume or unit mass decreases. For this reason, the addition amount of the binder is preferably 1 to 30% by mass, and more preferably 2 to 10% by mass.

-Filler The electrode compound material may contain the filler. As the material for forming the filler, any fibrous material that does not cause a chemical change in the secondary battery of the present invention can be used. Usually, fibrous fillers made of materials such as olefin polymers such as polypropylene and polyethylene, glass, and carbon are used. Although the addition amount of a filler is not specifically limited, 0-30 mass% is preferable in a dispersion.

-Current collector As the positive / negative electrode current collector, an electron conductor that does not cause a chemical change in the nonaqueous electrolyte secondary battery of the present invention is used. As the current collector of the positive electrode, in addition to aluminum, stainless steel, nickel, titanium, etc., the surface of aluminum or stainless steel is preferably treated with carbon, nickel, titanium, or silver. Among them, aluminum and aluminum alloys are preferable. More preferred.

  As the negative electrode current collector, aluminum, copper, stainless steel, nickel, and titanium are preferable, and aluminum, copper, and a copper alloy are more preferable.

As the shape of the current collector, a film sheet shape is usually used, but a net, a punched material, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like can also be used. The thickness of the current collector is not particularly limited, but is preferably 1 μm to 500 μm. Moreover, it is also preferable that the current collector surface is roughened by surface treatment.
An electrode mixture of the lithium secondary battery is formed by a member appropriately selected from these materials.

(Separator)
The separator used in the non-aqueous secondary battery of the present invention is particularly a material that has mechanical strength for electrically insulating the positive electrode and the negative electrode, ion permeability, and oxidation / reduction resistance at the contact surface between the positive electrode and the negative electrode. There is no limit. As such a material, a porous polymer material, an inorganic material, an organic-inorganic hybrid material, glass fiber, or the like is used. These separators preferably have a shutdown function for ensuring safety, that is, a function of closing the gap at 80 ° C. or higher to increase resistance and interrupting current, and the closing temperature is 90 ° C. or higher and 180 ° C. or lower. Preferably there is.

  The shape of the hole of the separator is usually circular or elliptical, and the size is 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm. Furthermore, it may be a rod-like or irregular-shaped hole as in the case of making by a stretching method or a phase separation method. The ratio of these gaps, that is, the porosity, is 20% to 90%, preferably 35% to 80%.

  The polymer material may be a single material such as cellulose nonwoven fabric, polyethylene, or polypropylene, or may be a composite material of two or more types. What laminated | stacked the 2 or more types of microporous film which changed the hole diameter, the porosity, the obstruction | occlusion temperature of a hole, etc. is preferable.

  As the inorganic substance, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and those having a particle shape or fiber shape are used. As the form, a thin film shape such as a non-woven fabric, a woven fabric, or a microporous film is used. In the thin film shape, those having a pore diameter of 0.01 μm to 1 μm and a thickness of 5 μm to 50 μm are preferably used. In addition to the independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, alumina particles having a 90% particle diameter of less than 1 μm are formed on both surfaces of the positive electrode as a porous layer using a fluororesin binder.

(Production of non-aqueous secondary battery)
As described above, the shape of the nonaqueous secondary battery of the present invention can be applied to any shape such as a sheet shape, a square shape, and a cylinder shape. A positive electrode active material or a mixture of negative electrode active materials is mainly used after being applied (coated), dried and compressed on a current collector.

  Hereinafter, with reference to FIG. 2, a configuration and a manufacturing method thereof will be described using the bottomed cylindrical lithium secondary battery 100 as an example. In a battery having a bottomed cylindrical shape, since the outer surface area with respect to the power generating element to be filled becomes small, it is preferable to design so that Joule heat generated by the internal resistance at the time of charging and discharging efficiently escapes to the outside. Moreover, it is preferable to design so that the filling ratio of the substance having high thermal conductivity is increased and the temperature distribution inside is reduced. FIG. 2 shows an example of a bottomed cylindrical lithium secondary battery 100. This battery is a bottomed cylindrical lithium secondary battery 100 in which a positive electrode sheet 14 and a negative electrode sheet 16 overlapped with a separator 12 are wound and accommodated in an outer can 18. In addition, in the figure, 20 is an insulating plate, 22 is a sealing plate, 24 is a positive electrode current collector, 26 is a gasket, 28 is a pressure sensitive valve body, and 30 is a current interruption element. In addition, although the illustration in the enlarged circle has changed hatching in consideration of visibility, each member corresponds to the whole drawing by reference numerals.

  First, a negative electrode active material is mixed with a binder or filler used as desired in an organic solvent to prepare a slurry-like or paste-like negative electrode mixture. The obtained negative electrode mixture is uniformly applied over the entire surface of both surfaces of the metal core as a current collector, and then the organic solvent is removed to form a negative electrode mixture layer. Further, the laminate of the current collector and the negative electrode composite material layer is rolled with a roll press or the like to prepare a predetermined thickness to obtain a negative electrode sheet (electrode sheet). At this time, the coating method of each agent, the drying of the coated material, and the method of forming the positive and negative electrodes may be in accordance with conventional methods.

  In the present embodiment, a cylindrical battery is taken as an example, but the present invention is not limited to this, for example, after the positive and negative electrode sheets produced by the above method are overlapped via a separator, After processing into a sheet battery as it is, or inserting it into a rectangular can after being folded and electrically connecting the can and the sheet, injecting an electrolyte and sealing the opening using a sealing plate A square battery may be formed.

  In any embodiment, the safety valve can be used as a sealing plate for sealing the opening. In addition to the safety valve, the sealing member may be provided with various conventionally known safety elements. For example, a fuse, bimetal, PTC element, or the like is preferably used as the overcurrent prevention element.

  In addition to the safety valve, as a countermeasure against the increase in the internal pressure of the battery can, a method of cutting the battery can, a method of cracking the gasket, a method of cracking the sealing plate, or a method of cutting the lead plate can be used. Further, the charger may be provided with a protection circuit incorporating measures against overcharge and overdischarge, or may be connected independently.

  For the can and lead plate, a metal or alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper, and aluminum, or alloys thereof are preferably used.

  As a method for welding the cap, the can, the sheet, and the lead plate, a known method (eg, direct current or alternating current electric welding, laser welding, ultrasonic welding) can be used. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.

(Pressure sensitive mechanism)
The non-aqueous secondary battery according to the present invention preferably has a pressure-sensitive mechanism (a mechanism that cuts off current when a predetermined pressure or higher is reached). Although the pressure-sensitive mechanism uses a pressure-sensitive valve as described above, various devices such as a device that detects a pressure change by a pressure-sensitive sensor and interrupts energization can be employed. FIG. 3 is a partial cross-sectional side view showing another example of the pressure sensitive valve.
As shown in FIG. 3, the current interrupting sealing body 50 is composed of a stainless steel positive electrode cap 51 formed in an inverted dish shape (cap shape) and a stainless steel bottom plate 54 formed in a dish shape. The The positive electrode cap 51 includes a convex portion 52 that bulges toward the outside of the battery, and a flat flange portion 53 that forms the bottom side of the convex portion 52, and a plurality of gas vents are formed at the corners of the convex portion 52. A hole 52a is provided. On the other hand, the bottom plate 54 includes a concave portion 55 that bulges toward the inside of the battery, and a flat flange portion 56 that constitutes the bottom side portion of the concave portion 55. A gas vent hole 55 a is provided at the corner of the recess 55.
Housed in the positive electrode cap 51 and the bottom plate 54 is a power lead-out plate 57 that deforms when the gas pressure inside the battery rises and exceeds a predetermined pressure. The power lead-out plate 57 includes a concave portion 57a and a flange portion 57b, and is formed of, for example, an aluminum foil having a thickness of 0.2 mm and a surface unevenness of 0.005 mm. The lowest portion of the recess 57 a is disposed in contact with the upper surface of the recess 55 of the bottom plate 54, and the flange portion 57 b is sandwiched between the flange portion 53 of the positive electrode cap 51 and the flange portion 56 of the bottom plate 54. . The positive electrode cap 51 and the bottom plate 54 are sealed in a liquid-tight manner by a sealing body insulating gasket 59 made of polypropylene (PP).
A PTC (Positive Temperature Coefficient) thermistor element 58 is disposed at a part of the upper portion of the flange portion 57b. When an overcurrent flows in the battery and an abnormal heat generation phenomenon occurs, the resistance value of the PTC thermistor element 58 increases. Increase to reduce overcurrent. Then, when the gas pressure inside the battery rises and exceeds a predetermined pressure, the recess 57a of the power lead-out plate 57 is deformed, so that the contact between the power lead-out plate 57 and the concave portion 55 of the bottom plate 54 is cut off and an overcurrent or short circuit occurs. The current is interrupted.
By using the electrolyte for a non-aqueous secondary battery according to the present invention, in the secondary battery having the pressure-sensitive mechanism, more gas is instantly generated at the time of overcharging, and accurate and quick interruption of current is possible. And

  It is preferable that the specific aromatic compound of the present invention does not generate gas during normal charging but generates an effective amount of gas during overcharging. Here, “to generate an effective amount of gas at the time of overcharging” means that the result of “Good” is obtained in the overcharged gas generation amount test and the charge life test in the examples described later.

  Here, when the meaning of terms is confirmed, normal charging means a state where charging is performed within the design voltage of the battery. For example, in a generally used constant current-constant voltage charging method, a method is used in which a constant current charge is performed until a set voltage is reached, and then a full charge is performed while the set voltage is maintained. The positive electrode potential during normal charging in the present application represents the positive electrode potential at the set voltage. On the other hand, overcharge refers to a state in which the battery is charged at a voltage exceeding the design voltage of the battery due to some factor.

[Applications of non-aqueous secondary batteries]

Secondary batteries called lithium batteries are secondary batteries that use the insertion and extraction of lithium for charge / discharge reactions (lithium ion secondary batteries), and secondary batteries that use precipitation and dissolution of lithium (lithium metal secondary batteries). ). In the present invention, application as a lithium ion secondary battery is preferable.
Since the nonaqueous secondary battery of the present invention can produce a secondary battery with good cycle performance, it is applied to various applications. Although there is no particular limitation on the application mode, for example, when installed in an electronic device, a notebook computer, a pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a cordless phone, a pager, a handy terminal, a mobile fax machine, a mobile phone Copy, portable printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, minidisc, electric shaver, walkie-talkie, electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, memory card, etc. It is done. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (such as pacemakers, hearing aids, and shoulder grinders). Furthermore, it can be used for various military use and space use. Moreover, it can also combine with a solar cell.

  Especially, it is preferable to apply to the application for which a high capacity | capacitance and a high rate discharge characteristic are requested | required from a viewpoint which exhibits the advantage of the safety | security at the time of an overcharge, and a high rate discharge characteristic. For example, in power storage facilities and the like that are expected to increase in capacity in the future, high safety is essential, and further compatibility of battery performance is required. In addition, electric vehicles are equipped with high-capacity secondary batteries and are expected to be charged every day at home, and even greater safety is required against overcharging (NEDO Technology Development Organization, Fuel Cell / Hydrogen Technology Development Department, Energy Storage Technology Development Office “NEDO Next-Generation Automotive Storage Battery Technology Development Roadmap 2008” (June 2009)). In addition, when starting and accelerating, it is necessary to discharge at a high rate, and it is important that the high-rate discharge capacity does not deteriorate even after repeated charging and discharging. According to the present invention, it is possible to exhibit the excellent effect correspondingly to such a usage pattern.

  The present invention will be described in more detail below, but the present invention is not construed as being limited thereto.

Example 1
(Preparation of electrolyte)
LiPF ₆ was added so that it might become 1 mol / L (12.7 mass%) with respect to the solution which mixed ethylene carbonate (EC) and ethyl methyl carbonate (EMC) by the volume ratio 1: 2, and becomes electrolyte solution used as a reference | standard Was made. On the other hand, it mixed with the additive and addition amount of the following table 1, and prepared the non-aqueous electrolyte.

(Production of 2032 type coin battery)
The positive electrode is prepared with 85% by mass of the active material in the table, the conductive auxiliary agent: 7.5% by mass of carbon black, the binder: 7.5% by mass of PVDF, and the negative electrode is 94% by mass of LTO, and the conductive auxiliary agent: carbon black 3 It was prepared with 3% by mass of binder and PVDF by mass. The separator is glass filter paper (manufactured by ADVANTEC: GA-55, thickness: 0.21 mm). Using the above positive and negative electrodes and separator, a 2032 type coin battery was prepared for each test electrolyte, and the following battery characteristic items were evaluated.

<Gas generation during overcharge>
Using a 2032 battery manufactured in the above procedure, in a 45 ° C. thermostat, after charging at a constant current of 1 C until the battery voltage reaches 3.55 V (positive electrode potential 5.1 V) at 0.9 mA, then at 0.18 mA. The battery was discharged at 0.2 C until the battery voltage reached 1.2 V (positive electrode potential 2.75 V), and the volume of the battery was measured. The measurement was carried out using a precision hydrometer set (precision balance: AUW120D, specific gravity measurement kit: SMK-401) manufactured by Shimadzu Corporation. The ratio of the increase in battery volume after this overcharge test to the volume during battery production was defined as the amount of gas generated during overcharge.

  For reference, a schematic cross-sectional view of the battery is shown in FIG. In this example, the top and bottom lids shown in the figure were made of SUS (plate thickness 250 μm), the diameter of the 2032 battery was 20 mm, and the thickness was 3.2 mm.

Gas generation during overcharge
= (Battery volume after overcharge test-Battery volume at creation) / Battery volume at creation x 100

This gas generation amount is less than 1 Bad
1 to less than 3 Fair
3 or more Good
As evaluated.

<Charge life test>
Using a 2032 battery manufactured in the same manner except that the separator was changed to a polypropylene microporous membrane 24 μm thick, until the battery voltage reached 2.65 V (positive electrode potential 4.2 V) at 2 mA in a thermostatic bath at 30 ° C. 1C constant current charging was performed. Thereafter, charging was performed for 1 month at a constant voltage of 2.65 V (positive electrode potential 4.2 V). Next, 0.2 C constant current discharge was performed until the battery voltage became 1.2 V (positive electrode potential 2.75 V) at 0.4 mA, and the discharge capacity (mAh) and the volume of the battery were measured. The ratio of the discharge capacity after one month to the initial discharge capacity was defined as the capacity retention rate, and the ratio of the increase in battery volume after the test to the battery production volume was defined as the amount of gas generated during the charge life test.

This gas generation amount is 0 or more and less than 1 Good
1 to less than 3 Fair
3 or more Bad
As evaluated.

  The results are shown in Table 1 below.

試験Ｎｏ．：ｃで始まるものは比較例
化合物添加量：電解液全量（電解質を含む）に対する含有率（質量％）
ＬＴＯ：チタン酸リチウム
ＬＣＯ：ＬｉＣｏＯ_２
ＮＭＣ：ＬｉＮｉ_０．３３Ｃｏ_０．３３Ｍｎ_０．３３Ｏ_２

Test No. : Starting with c is a comparative example Compound addition amount: Content (% by mass) with respect to the total amount of electrolyte (including electrolyte)
LTO: lithium titanate LCO: LiCoO ₂
NMC: LiNi _0.33 Co _0.33 Mn _0.33 O ₂

  From the above results, it can be seen that by using the specific aromatic compound according to the present invention, it is possible to achieve both high overcharge prevention based on gas generation from the non-aqueous electrolyte and deterioration suppression (cycle characteristics) of battery performance. .

(Example 2)
Changed to the negative electrode active material shown in Table 2, the charge voltage of the amount of gas generated during overcharge is 5.0 V (positive electrode potential 5.1 V), the discharge voltage is 2.65 V (positive electrode voltage 2.75 V), and the charge life test Example 1 except that the charging voltage was changed to 4.1 V (positive electrode voltage 4.2 V), the constant voltage condition was changed to 4.1 V (positive electrode potential 4.2 V), and the discharge voltage was changed to 2.65 V (2.75 V). In the same manner as above, a gas generation amount test and a charge life test were performed during overcharge. The results are shown in Table 2.

黒鉛：天然球状グラファイト
黒鉛／Ｓｉ：特開２０１２−４３５４７等を参考に作製
Ｓｎ：特開平１０−７４５３７を参考に作製

Graphite: natural spherical graphite Graphite / Si: produced with reference to JP2012-43547, etc. Sn: produced with reference to JP10-74537A

  From the above results, according to the electrolyte for a non-aqueous secondary battery and the non-aqueous secondary battery of the present invention, high overcharge prevention based on gas generation from the non-aqueous electrolyte and prolonging its charge life are achieved. It can be seen that both can be achieved. Moreover, it is understood that the compatibility with the high potential negative electrode and the positive electrode is good, and the performance is further improved by using these.

  FIG. 5 shows a graph of the charging curve during the overcharge test. This measurement was performed as follows. The amount of electricity during the overcharge test of Example 1 is plotted on the horizontal axis, and the positive electrode potential (battery voltage +1.55 V) is plotted on the vertical axis. From this result, if there is a sufficient difference between the reaction start potential (maximum value of the curve) and the gas generation potential (minimum value of the curve), it shows stable battery behavior without generating gas during normal operation, and a short time during overcharge. It can be seen that a large amount of gas can be released, that is, a reaction disc can be added. The difference between the reaction initiation potential and the gas generation potential is preferably 0.08 V or more, more preferably 0.1 V or more, further preferably 0.15 V or more, and particularly preferably 0.2 V or more. Although there is no upper limit in particular, it is practical that it is 2V or less.

C positive electrode (positive electrode composite)
1 Positive electrode conductive material (current collector)
2 Positive electrode active material layer A Positive electrode (positive electrode mixture)
3 Negative electrode conductive material (current collector)
4 Negative electrode active material layer 5 Nonaqueous electrolyte 6 Operating means 7 Wiring 9 Separator 10 Lithium ion secondary battery 12 Separator 14 Positive electrode sheet 16 Negative electrode sheet 18 Exterior can 20 also serving as negative electrode Insulating plate 22 Sealing plate 24 Positive electrode current collector 26 Gasket 28 Pressure-sensitive valve body 30 Current interrupting element 100 Bottomed cylindrical lithium secondary battery 50 Current interrupting sealing body 51 Positive electrode cap 52 Convex part 52a Gas vent hole 53 Flange part 54 Bottom plate 55 Concave part 56 Flange part 57 Power outlet plate 57a Concave part 57
57b Flange part 58 PTC thermistor element 59 Insulating gasket 61 for sealing body Negative electrode terminal (upper cover)
62 Negative electrode 63 Separator (including electrolyte)
64 Gasket (sealing material)
65 Positive electrode 66 Positive electrode tube (bottom cover)

Claims (19)

A nonaqueous secondary battery comprising the following negative electrode, the following positive electrode, and an electrolyte for a nonaqueous secondary battery,
The non-aqueous secondary battery in which the electrolyte solution for a non-aqueous secondary battery contains a specific aromatic compound represented by the following formula (1) or (2), an organic solvent, and the following electrolyte.

(In the formula, R ^{11 to} R ¹⁴ , R ^a , R ²¹ and R ²² each independently represent a hydrogen atom and a monovalent substituent. These groups are formed by bonding or condensing adjacent substituents. (It may form a ring. N represents an integer of 1 to 8. p represents an integer of 1 to 6. m represents an integer of 1 to 3.)
(Negative electrode: Metal ions belonging to Group 1 or Group 2 can be inserted and released, and a material containing carbon atom (C), silicon atom (Si), or titanium atom (Ti) is used as an active material)
(Positive electrode: A material capable of inserting and releasing metal ions belonging to Group 1 or Group 2 is used as an active material)
(Electrolyte: Metal salt containing ions of metals belonging to Group 1 or Group 2 of the periodic rule)   The non-aqueous secondary battery according to claim 1, wherein the specific aromatic compound is included in the electrolytic solution at 1% by mass to 40% by mass.   The nonaqueous secondary battery according to claim 1, wherein the negative electrode active material is lithium titanate.   The non-aqueous secondary battery according to claim 1, wherein at least one of Ra is an electron-withdrawing substituent.   The nonaqueous secondary battery according to any one of claims 1 to 4, wherein the positive electrode active material contains manganese and / or nickel element.   M in said Formula (1) or (2) is 1, The nonaqueous secondary battery of any one of Claims 1-5. The non-aqueous secondary battery according to claim 1, wherein at least one of R ¹⁴ and at least one of R ^{22 in} the formula (1) or (2) is a hydrogen atom.   The nonaqueous secondary battery according to any one of claims 1 to 7, further comprising a mechanism that cuts off an electric current when the pressure exceeds a predetermined pressure. The nonaqueous secondary battery according to claim 1, wherein the active material of the positive electrode includes a transition metal oxide represented by any of the following formulas (MA) to (MC).
Li _a M ¹ O _b (MA)
Li _c M ² ₂ O _d (MB)
Li _e M ³ (PO ₄ ) _f ... (MC)
(In the formula, M ¹ and M ² each independently represent one or more elements selected from Co, Ni, Fe, Mn, Cu, and V. M ³ independently represents V, Ti. , Cr, Mn, Fe, Co, Ni, and Cu represent one or more elements selected from the group consisting of M ^{1 to} M ³ , part of which is the first (Ia) of the periodic table other than lithium ) Group element, Group 2 (IIa) element, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B may be substituted. a represents 0 to 1.2, b represents 1 to 3, c represents 0 to 2, d represents 3 to 5, e represents 0 to 2, and f represents 1 to 5. )   The active material of the positive electrode is lithium cobaltate, lithium manganate, lithium nickelate, nickel manganese lithium cobaltate, lithium manganese nickelate, nickel cobalt lithium aluminum phosphate, or lithium iron phosphate. The non-aqueous secondary battery according to claim 1.   The non-aqueous secondary battery according to claim 1, wherein the electrolytic solution contains a linear carbonate compound.   The nonaqueous secondary battery according to any one of claims 1 to 11, wherein the electrolyte does not generate a gas during normal charging but generates an effective amount of gas during overcharging. The electrolyte solution for non-aqueous secondary batteries containing the specific aromatic compound represented by following formula (1) or (2), an organic solvent, and the following electrolyte.

(In the formula, R ^{11 to} R ¹⁴ , R ^a , R ²¹ and R ²² each independently represent a hydrogen atom and a monovalent substituent. These groups are formed by bonding or condensing adjacent substituents. (It may form a ring. N represents an integer of 1 to 8. p represents an integer of 1 to 6. m represents an integer of 1 to 3.)
(Electrolyte: Metal salt containing ions of metals belonging to Group 1 or Group 2 of the periodic rule)   The electrolyte solution for a non-aqueous secondary battery according to claim 13, wherein the specific aromatic compound releases a gas when charged at a positive electrode potential of 4.5 V (Li / Li + standard) or more.   The electrolyte solution for a non-aqueous secondary battery according to claim 13 or 14, wherein at least one of Ra is an electron-attracting substituent.   Furthermore, the electrolyte solution for nonaqueous secondary batteries of any one of Claims 13-15 containing a linear carbonate compound.   The electrolyte solution for nonaqueous secondary batteries according to any one of claims 13 to 16, wherein a gas is not generated during normal charging but an effective amount of gas is generated during overcharging. An additive for a non-aqueous secondary battery electrolyte comprising a specific aromatic compound represented by the following formula (1) or (2).

(In the formula, R ^{11 to} R ¹⁴ , R ^a , R ²¹ , and R ²² each independently represent a hydrogen atom and a monovalent substituent. At least one of Ra is a substituent having a positive Hammett σp value. In these groups, adjacent substituents may be bonded or condensed to form a ring, n represents an integer of 1 to 8, and p represents an integer of 1 to 6. m Represents an integer of 1 to 3.) The overcharge test includes a specific aromatic compound that includes a difference between a maximum value and a minimum value of an electric charge-positive voltage charging curve at the time of charging at 1C of 0.08 V or more. Non-aqueous secondary battery.

Images