JP2014127354A - Electrolyte for nonaqueous secondary battery, nonaqueous secondary battery, and additive for electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous secondary battery capable of achieving both high overcharge prevention properties and deterioration suppression of battery performance even if a positive electrode potential is used at high potential, and also to provide an electrolyte for the nonaqueous secondary battery used for the same.SOLUTION: An electrolyte for a nonaqueous secondary battery contains at least one of nitrogen-containing compounds having a specific structure, a metal ion belonging to group I or group II of the periodic table or salt thereof, and an organic solvent.

Description

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

  Recently, secondary batteries called lithium ion batteries, which are attracting attention, use secondary batteries (so-called lithium ion secondary batteries) that use insertion and extraction of lithium in charge and discharge reactions, and precipitation and dissolution of lithium. They are roughly classified into secondary batteries (so-called lithium metal secondary batteries). These realize charging and discharging with a large energy density compared to lead batteries and nickel cadmium batteries. In recent years, application to portable electronic devices such as camera-integrated VTRs (video tape recorders), mobile phones, and notebook personal computers has become widespread by utilizing this characteristic. With the further expansion of applications, the development of secondary batteries that are lighter and have higher energy density as power sources for portable electronic devices is being promoted. Furthermore, in recent years, miniaturization, long life, and high safety have been strongly demanded.

  By the way, a lithium ion secondary battery and a lithium metal secondary battery (hereinafter collectively referred to simply as a lithium secondary battery) have a problem of overcharging as an inherent problem to be solved. . This leads to a situation where the electrode is short-circuited or ignited when the secondary battery reaches a fully charged state but continues to be charged. In particular, it is a problem peculiar to a lithium secondary battery using an organic electrolyte, and a sufficient response has been desired from the viewpoint of ensuring safety in use.

  On the other hand, usually, a measure is taken on the side of the electric device to which the battery is attached, and a charging circuit is incorporated so that the supply of electricity is cut off when the battery reaches full charge. However, even though it is extremely rare, it is assumed that a malfunction or the like occurs in the above circuit, resulting in an overcharged state. 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 preventing the overcharge as described above. Among them, a representative example is biphenyl disclosed in Patent Document 1 below. Patent Documents 2 and 3 describe attempts to ensure safety during overcharge by adding an amine compound.

Japanese Patent Application Laid-Open No. 07-302614 Japanese Patent Laid-Open No. 2001-15158 JP 2002-50398 A

  As the performance required for the overcharge inhibitor, it is desired that the operation is not hindered at a normal charging potential, and that an effect is quickly manifested only at the time of overcharging. Biphenyl, which is a conventional overcharge inhibitor, reacts not only during overcharge but also during normal charge, and when charging and discharging are repeated, resistance increases and capacity deterioration is observed. Further, pyrrole and aniline are known as compounds that form a resistance film by oxidative polymerization on the positive electrode. In these compounds, since the oxidation potential of the multimer produced by the oxidation reaction is lower than the oxidation potential of pyrrole or aniline, further oxidative polymerization is likely to occur, and a film can be formed efficiently. On the other hand, since these compounds having NH bonds have a low oxidation potential, they react during normal charging like biphenyl, and when charging and discharging are repeated, resistance increases and capacity deterioration is observed. On the other hand, from the viewpoint of improving energy density, there is a strong demand to use the positive electrode potential at a higher potential. However, when the positive electrode potential is used at a higher potential, the capacity deterioration is significant when the above charge / discharge is repeated, and overcharge From the viewpoint of prevention, improvement of energy density and suppression of battery performance deterioration, it is still insufficient.

On the other hand, the lithium secondary battery has been greatly improved since ten years before the overcharge prevention measure was taken in Patent Document 1. As a result, the structure and performance of the battery are greatly different. One example is the performance of the positive electrode. In Patent Document 1, LiCoO ₂ (electrode potential: 4.1 V) is employed as the positive electrode active material. On the other hand, recently, a LiNiMnO-based positive electrode active material or the like has been developed, and the electrode potential has reached 4.25 V or more. According to the confirmation of the present inventors, in the positive electrode having such a high potential, the biphenyl proposed in Patent Document 1 and the amine compounds proposed in Patent Documents 2 and 3 have sufficient overcharge prevention and normality. It has been found that it is not possible to ensure compatibility of battery deterioration during use.

  Therefore, the present invention provides a non-aqueous secondary battery that can achieve both high overcharge prevention and suppression of deterioration of battery performance even when the positive electrode potential is used at a high potential, and an electrolyte for the non-aqueous secondary battery used therefor With the goal.

［（Ａ１）中、Ｘ^１は電子吸引性基を表す。Ｌ^１１は連結基を表す。Ｌ^１２は−Ｃ（＝Ｏ）−結合、炭素−炭素多重結合、窒素−窒素単結合または多重結合、および炭素−窒素多重結合から選ばれる少なくとも１種を有し、窒素原子とともに環Ｃｙを形成する基を表す。Ｌ^１２は＞Ｎ−Ｌ^１１−（Ｘ^１）_ｎ１基を更に含んでいてもよい。ｎ１は１〜３の整数を表す。］
［（Ａ２）中、Ｒ^２１はアルキル基、アリール基、アルコキシ基、アリールオキシ基、アラルキル基、アルケニル基、または含窒素基を表す。Ｌ^１２は（Ａ１）におけるＬ^１２と同義である。Ｌ^１２は＞Ｎ−Ｃ（＝Ｏ）−Ｒ^２１基を更に含んでいてもよい。］
［（Ａ３）中、Ｌ^３１は−Ｓ（＝Ｏ）−または−Ｓ（＝Ｏ）_２−を表す。Ｒ^３１およびＲ^３２はそれぞれアルキル基、アリール基、ヘテロアリール基、アラルキル基、アルキルスルホニル基、アリールスルホニル基、アシル基、アルコキシカルボニル基、または−Ｌ^３１−Ｒ^３３を表す。Ｒ^３１とＲ^３２とは結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成していてもよい。Ｃｙは（Ａ１）におけるＣｙと同義である。Ｒ^３３はアルキル基、アリール基、アラルキル基、または含窒素基を表す。ただし、Ｒ^３１、Ｒ^３２のうち少なくとも１つがアリール基もしくはヘテロアリール基であるか、Ｒ^３１とＲ^３２とが結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成している。］
［（Ａ４）中、Ｒ^４１およびＲ^４２はそれぞれアルキル基、アリール基、ヘテロアリール基、アラルキル基、アルキルスルホニル基、アリールスルホニル基、アシル基、アルコキシカルボニル基、またはリン含有基を表す。Ｒ^４１とＲ^４２とは結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成していてもよい。Ｃｙは（Ａ１）におけるＣｙと同義である。Ｒ^４３およびＲ^４４はそれぞれアルキル基、アリール基、アラルキル基、アルコキシ基、アリールオキシ基、アラルキルオキシ基、ハロゲン原子、または含窒素基を表す。ただし、Ｒ^４１およびＲ^４２のうち少なくとも１つがアリール基であるか、Ｒ^４１とＲ^４２とが結合もしくは縮合して窒素原子とともに環構造を形成している。］
［（Ａ５）中、Ｒ^５１およびＲ^５２はそれぞれアルキル基、アリール基、ヘテロアリール基、アラルキル基、アルキルスルホニル基、アリールスルホニル基、アルコキシカルボニル基、またはアシル基を表す。Ｒ^５１とＲ^５２とは結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成していてもよい。Ｃｙは（Ａ１）におけるＣｙと同義である。Ｒ^５３〜Ｒ^５５はそれぞれ水素原子、アルキル基、アリール基、アラルキル基、または含窒素基を表す。ただし、Ｒ^５１およびＲ^５２のうち少なくとも１つがアリール基であるか、またはＲ^５１とＲ^５２とが結合もしくは縮合して窒素原子とともに環構造を形成する。］
［（Ａ６）中、Ｒ^６１およびＲ^６２はそれぞれアルキル基、アリール基、ヘテロアリール基、アラルキル基、アルキルスルホニル基、アリールスルホニル基、アルコキシカルボニル基、またはアシル基を表す。Ｒ^６１とＲ^６２とは結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成していていてもよい。Ｃｙは（Ａ１）におけるＣｙと同義である。Ｒ^６３は水素原子、アルキル基、アリール基、またはアラルキル基を表す。ｎ６は２〜４を表す。］
［含窒素化合物（Ａ）は（Ａ１）〜（Ａ６）の任意の位置で連結された多量体あってもよい。］
〔２〕Ｌ^１２が窒素原子とともに形成する環構造が−Ｃ（＝Ｏ）−結合、窒素−窒素単結合または多重結合を含有する〔１〕に記載の非水二次電池用電解液。
〔３〕Ｌ^１２が窒素原子とともに形成する環構造が下式で表される構造である〔１〕または〔２〕に記載の非水二次電池用電解液（式中＊は結合位置を表し、＊が１つの場合、＊はＬ^１１と結合する。＊が二つ以上の場合、少なくとも１つがＬ^１１と結合する。残りの＊は水素原子または任意の置換基Ｒ^ａと結合する。式中の水素原子は任意の置換基Ｒ^ｂで置換されていてもよい。）

〔４〕Ｌ^１１が炭素数１〜３のアルキレン基である〔１〕または〔２〕に記載の非水二次電池用電解液。
〔５〕Ｘ^１がアルコキシカルボニル基、アシル基、アシルオキシ基、シアノ基、スルホニル基含有基、およびハロゲン置換アルキル基から選ばれる〔１〕〜〔４〕のいずれか１項に記載の非水二次電池用電解液。
〔６〕更に、（Ａ）とは異なる化合物として、芳香族性化合物、ニトリル化合物、ハロゲン置換カーボネート化合物、リン含有化合物、硫黄含有化合物、ケイ素含有化合物、及び重合性化合物から選ばれる少なくとも１種の化合物を含有する〔１〕〜〔５〕のいずれか１項に記載の非水二次電池用電解液。
〔７〕（Ｘ^１）_ｎ１−Ｌ^１−が、下記式（ａ１）〜（ａ１９）のいずれかで表される原子群である〔１〕〜〔６〕のいずれか１項に記載の非水二次電池用電解液。

（Ｒ^３０１〜Ｒ^３０３は有機基である。Ｒ^３０４はハロゲン置換アルキル基である。Ｒ^３０５は有機連結基を表す。ｎ２は１〜５を表す。）
〔８〕含窒素化合物（Ａ）を０．００１〜１０質量％で含有する〔１〕〜〔７〕のいずれか１項に記載の非水二次電池用電解液。
〔９〕正極、負極、および〔１〕〜〔８〕のいずれか１項に記載の非水二次電池用電解液を具備する非水二次電池。
〔１０〕ニッケル、コバルト、およびマンガンのうち少なくとも１種を有する化合物を正極の活物質として用いた〔９〕に記載の非水二次電池。
〔１１〕チタン酸リチウム（ＬＴＯ）または（複合）炭素材料を負極の活物質として用いた〔９〕または〔１０〕に記載の非水二次電池。
〔１２〕電池の通常充電正極電位以下では作用せず、過充電時に酸化され、電池の抵抗を上昇させる過充電防止剤を含有する二次電池用電解液であって、過充電防止剤が式（Ａ１）〜（Ａ６）のいずれかで表される化合物少なくとも１種からなる非水二次電池用電解液。

［（Ａ１）中、Ｘ^１は電子吸引性基を表す。Ｌ^１１は連結基を表す。Ｌ^１２は−Ｃ（＝Ｏ）−結合、炭素−炭素多重結合、窒素−窒素単結合または多重結合、および炭素−窒素多重結合から選ばれる少なくとも１種を有し、窒素原子とともに環Ｃｙを形成する基を表す。Ｌ^１２は＞Ｎ−Ｌ^１１−（Ｘ^１）_ｎ１基を更に含んでいてもよい。ｎ１は１〜３の整数を表す。］
［（Ａ２）中、Ｒ^２１はアルキル基、アリール基、アルコキシ基、アリールオキシ基、アラルキル基、アルケニル基、または含窒素基を表す。Ｌ^１２は（Ａ１）におけるＬ^１２と同義である。Ｌ^１２は＞Ｎ−Ｃ（＝Ｏ）−Ｒ^２１基を更に含んでいてもよい。］
［（Ａ３）中、Ｌ^３１は−Ｓ（＝Ｏ）−または−Ｓ（＝Ｏ）_２−を表す。Ｒ^３１およびＲ^３２はそれぞれアルキル基、アリール基、ヘテロアリール基、アラルキル基、アルキルスルホニル基、アリールスルホニル基、アシル基、アルコキシカルボニル基、または−Ｌ^３１−Ｒ^３３を表す。Ｒ^３１とＲ^３２とは結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成していてもよい。Ｃｙは（Ａ１）におけるＣｙと同義である。Ｒ^３３はアルキル基、アリール基、アラルキル基、または含窒素基を表す。ただし、Ｒ^３１、Ｒ^３２のうち少なくとも１つがアリール基もしくはヘテロアリール基であるか、Ｒ^３１とＲ^３２とが結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成している。］
［（Ａ４）中、Ｒ^４１およびＲ^４２はそれぞれアルキル基、アリール基、ヘテロアリール基、アラルキル基、アルキルスルホニル基、アリールスルホニル基、アシル基、アルコキシカルボニル基、またはリン含有基を表す。Ｒ^４１とＲ^４２とは結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成していてもよい。Ｃｙは（Ａ１）におけるＣｙと同義である。Ｒ^４３およびＲ^４４はそれぞれアルキル基、アリール基、アラルキル基、アルコキシ基、アリールオキシ基、アラルキルオキシ基、ハロゲン原子、または含窒素基を表す。ただし、Ｒ^４１およびＲ^４２のうち少なくとも１つがアリール基であるか、Ｒ^４１とＲ^４２とが結合もしくは縮合して窒素原子とともに環構造を形成している。］
［（Ａ５）中、Ｒ^５１およびＲ^５２はそれぞれアルキル基、アリール基、ヘテロアリール基、アラルキル基、アルキルスルホニル基、アリールスルホニル基、アルコキシカルボニル基、またはアシル基を表す。Ｒ^５１とＲ^５２とは結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成していてもよい。Ｃｙは（Ａ１）におけるＣｙと同義である。Ｒ^５３〜Ｒ^５５はそれぞれ水素原子、アルキル基、アリール基、アラルキル基、または含窒素基を表す。ただし、Ｒ^５１およびＲ^５２のうち少なくとも１つがアリール基であるか、またはＲ^５１とＲ^５２とが結合もしくは縮合して窒素原子とともに環構造を形成する。］
［（Ａ６）中、Ｒ^６１およびＲ^６２はそれぞれアルキル基、アリール基、ヘテロアリール基、アラルキル基、アルキルスルホニル基、アリールスルホニル基、アルコキシカルボニル基、またはアシル基を表す。Ｒ^６１とＲ^６２とは結合もしくは縮合して窒素原子とともに環構造Ｃｙを形成していていてもよい。Ｃｙは（Ａ１）におけるＣｙと同義である。Ｒ^６３は水素原子、アルキル基、アリール基、またはアラルキル基を表す。ｎ６は２〜４を表す。］
［含窒素化合物（Ａ）は（Ａ１）〜（Ａ６）の任意の位置で連結された多量体あってもよい。］
〔１３〕電池の通常充電正極電位が４．２５Ｖ（Ｌｉ／Ｌｉ^＋基準）以上である〔１２〕に記載の非水二次電池用電解液。
〔１４〕インピーダンス測定により算出した次式の抵抗上昇率が５以上である〔１２〕または〔１３〕に記載の非水二次電池用電解液。
抵抗上昇率＝（正極電位５Ｖまで充電した後の抵抗）
／（正極電位４．１Ｖまで充電した後の抵抗）
〔１５〕正極、負極、および〔１２〕〜〔１４〕のいずれか１項に記載の非水二次電池用電解液を具備する非水二次電池であって、
正極はその活物質として４．２５Ｖ以上の電極電位（Ｌｉ／Ｌｉ^＋基準）を示す材料を有してなり、過充電時に電池の抵抗が上昇する非水二次電池。
〔１６〕インピーダンス測定により算出した次式の抵抗上昇率が５以上である〔１５〕に記載の非水二次電池。
抵抗上昇率＝（正極電位５Ｖまで充電した後の抵抗）
／（正極電位４．１Ｖまで充電した後の抵抗）
〔１７〕式（ＡＡ）で表される非水二次電池の電解液用添加剤であって、（ＡＡ）の酸化開始電位が、（ＡＡ）の置換基Ｚの替わりに水素原子となった（ＢＢ）の酸化開始電位よりも高い電解液用添加剤。

（式中、Ｚ、Ｒ^１０１、Ｒ^１０２は有機基である。）
〔１８〕Ｚが（ＡＡ）の酸化により脱離する官能基である〔１７〕に記載の電解液用添加剤。
〔１９〕添加剤（ＡＡ）が式（Ａ１）〜（Ａ６）のいずれかで表される含窒素化合物（Ａ）である〔１７〕または〔１８〕に記載の電解液用添加剤。 The above problem has been solved by the following means.
[1] At least one nitrogen-containing compound (A) having a structure represented by any of the following formulas (A1) to (A6), a metal ion belonging to Group 1 or Group 2 of the periodic table, or a salt thereof An electrolyte for non-aqueous secondary batteries containing an organic solvent.

[In (A1), X ¹ represents an electron-withdrawing group. L ¹¹ represents a linking group. L ¹² has at least one selected from —C (═O) — bond, carbon-carbon multiple bond, nitrogen-nitrogen single bond or multiple bond, and carbon-nitrogen multiple bond, and forms a ring Cy together with a nitrogen atom. Represents a group. L ^{12 is> N-L 11 - (X} 1) may further comprise _n1 group. n1 represents an integer of 1 to 3. ]
[In (A2), R ²¹ represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an aralkyl group, an alkenyl group, or a nitrogen-containing group. L ¹² has the same meaning as ^{L 12} in (A1). L ¹² may further include a> N—C (═O) —R ²¹ group. ]
[In (A3), L ³¹ represents —S (═O) — or —S (═O) ₂ —. R ³¹ and R ³² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an alkoxycarbonyl group, or —L ³¹ —R ³³ . R ³¹ and R ³² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ³³ represents an alkyl group, an aryl group, an aralkyl group, or a nitrogen-containing group. However, at least one of R ³¹ and R ³² is an aryl group or a heteroaryl group, or R ³¹ and R ³² are bonded or condensed to form a ring structure Cy together with a nitrogen atom. ]
[In (A4), R ⁴¹ and R ⁴² each represent an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an alkoxycarbonyl group, or a phosphorus-containing group. R ⁴¹ and R ⁴² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ⁴³ and R ⁴⁴ each represents an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, an aralkyloxy group, a halogen atom, or a nitrogen-containing group. However, at least one of R ⁴¹ and R ⁴² is an aryl group, or R ⁴¹ and R ⁴² are bonded or condensed to form a ring structure with a nitrogen atom. ]
[In (A5), R ⁵¹ and R ⁵² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, or an acyl group. R ⁵¹ and R ⁵² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ^{53 to} R ⁵⁵ each represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a nitrogen-containing group. However, at least one of R ⁵¹ and R ⁵² is an aryl group, or R ⁵¹ and R ⁵² are bonded or condensed to form a ring structure together with a nitrogen atom. ]
[In (A6), R ⁶¹ and R ⁶² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, or an acyl group. R ⁶¹ and R ⁶² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ⁶³ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. n6 represents 2-4. ]
[The nitrogen-containing compound (A) may be a multimer linked at any position of (A1) to (A6). ]
[2] The electrolyte solution for a non-aqueous secondary battery according to [1], wherein the ring structure formed by L ¹² together with the nitrogen atom contains a —C (═O) — bond, a nitrogen-nitrogen single bond, or a multiple bond.
[3] The electrolyte for a nonaqueous secondary battery according to [1] or [2], wherein the ring structure formed by L ¹² together with the nitrogen atom is represented by the following formula (wherein * represents a bonding position) * If there is one, * if binds to L ^11. * is more than one, at least one of which binds to L ^11. the remaining * bonds with a hydrogen atom or an arbitrary substituent R ^a. formula The hydrogen atom therein may be substituted with an arbitrary substituent R ^b .)

[4] The electrolyte solution for a non-aqueous secondary battery according to [1] or [2], wherein L ¹¹ is an alkylene group having 1 to 3 carbon atoms.
[5] The nonaqueous solution according to any one of [1] to [4], wherein X ¹ is selected from an alkoxycarbonyl group, an acyl group, an acyloxy group, a cyano group, a sulfonyl group-containing group, and a halogen-substituted alkyl group. Secondary battery electrolyte.
[6] Further, the compound different from (A) is at least one selected from an aromatic compound, a nitrile compound, a halogen-substituted carbonate compound, a phosphorus-containing compound, a sulfur-containing compound, a silicon-containing compound, and a polymerizable compound. [1] The electrolyte solution for non-aqueous secondary batteries of any one of [5] containing a compound.
[7] (X ¹ ) _n1 -L ¹ -is an atomic group represented by any one of the following formulas (a1) to (a19), according to any one of [1] to [6] Electrolyte for water secondary battery.

(R ^{301 to} R ³⁰³ are organic groups. R ³⁰⁴ is a halogen-substituted alkyl group. R ³⁰⁵ represents an organic linking group. N2 represents 1 to 5.)
[8] The electrolyte solution for a non-aqueous secondary battery according to any one of [1] to [7], containing the nitrogen-containing compound (A) in an amount of 0.001 to 10% by mass.
[9] A nonaqueous secondary battery comprising the positive electrode, the negative electrode, and the electrolyte for a nonaqueous secondary battery according to any one of [1] to [8].
[10] The nonaqueous secondary battery according to [9], wherein a compound having at least one of nickel, cobalt, and manganese is used as the positive electrode active material.
[11] The nonaqueous secondary battery according to [9] or [10], wherein lithium titanate (LTO) or (composite) carbon material is used as an active material for the negative electrode.
[12] A secondary battery electrolyte containing an overcharge inhibitor that does not act below the normal charge positive electrode potential of the battery, is oxidized during overcharge, and increases the resistance of the battery. An electrolyte solution for a non-aqueous secondary battery comprising at least one compound represented by any one of (A1) to (A6).

[In (A1), X ¹ represents an electron-withdrawing group. L ¹¹ represents a linking group. L ¹² has at least one selected from —C (═O) — bond, carbon-carbon multiple bond, nitrogen-nitrogen single bond or multiple bond, and carbon-nitrogen multiple bond, and forms a ring Cy together with a nitrogen atom. Represents a group. L ^{12 is> N-L 11 - (X} 1) may further comprise _n1 group. n1 represents an integer of 1 to 3. ]
[In (A2), R ²¹ represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an aralkyl group, an alkenyl group, or a nitrogen-containing group. L ¹² has the same meaning as ^{L 12} in (A1). L ¹² may further include a> N—C (═O) —R ²¹ group. ]
[In (A3), L ³¹ represents —S (═O) — or —S (═O) ₂ —. R ³¹ and R ³² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an alkoxycarbonyl group, or —L ³¹ —R ³³ . R ³¹ and R ³² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ³³ represents an alkyl group, an aryl group, an aralkyl group, or a nitrogen-containing group. However, at least one of R ³¹ and R ³² is an aryl group or a heteroaryl group, or R ³¹ and R ³² are bonded or condensed to form a ring structure Cy together with a nitrogen atom. ]
[In (A4), R ⁴¹ and R ⁴² each represent an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an alkoxycarbonyl group, or a phosphorus-containing group. R ⁴¹ and R ⁴² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ⁴³ and R ⁴⁴ each represents an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, an aralkyloxy group, a halogen atom, or a nitrogen-containing group. However, at least one of R ⁴¹ and R ⁴² is an aryl group, or R ⁴¹ and R ⁴² are bonded or condensed to form a ring structure with a nitrogen atom. ]
[In (A5), R ⁵¹ and R ⁵² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, or an acyl group. R ⁵¹ and R ⁵² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ^{53 to} R ⁵⁵ each represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a nitrogen-containing group. However, at least one of R ⁵¹ and R ⁵² is an aryl group, or R ⁵¹ and R ⁵² are bonded or condensed to form a ring structure together with a nitrogen atom. ]
[In (A6), R ⁶¹ and R ⁶² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, or an acyl group. R ⁶¹ and R ⁶² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ⁶³ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. n6 represents 2-4. ]
[The nitrogen-containing compound (A) may be a multimer linked at any position of (A1) to (A6). ]
[13] The electrolyte for a nonaqueous secondary battery according to [12], wherein the normal charge positive electrode potential of the battery is 4.25 V (Li / Li ⁺ reference) or more.
[14] The electrolyte solution for a nonaqueous secondary battery according to [12] or [13], wherein the rate of increase in resistance of the following formula calculated by impedance measurement is 5 or more.
Resistance increase rate = (resistance after charging to positive electrode potential 5V)
/ (Resistance after charging to positive electrode potential 4.1V)
[15] A nonaqueous secondary battery comprising the positive electrode, the negative electrode, and the electrolyte solution for a nonaqueous secondary battery according to any one of [12] to [14],
The positive electrode is a non-aqueous secondary battery that has a material exhibiting an electrode potential (Li / Li ⁺ reference) of 4.25 V or higher as its active material, and the resistance of the battery increases during overcharge.
[16] The nonaqueous secondary battery according to [15], wherein the rate of increase in resistance of the following formula calculated by impedance measurement is 5 or more.
Resistance increase rate = (resistance after charging to positive electrode potential 5V)
/ (Resistance after charging to positive electrode potential 4.1V)
[17] An additive for an electrolyte of a non-aqueous secondary battery represented by the formula (AA), wherein the oxidation initiation potential of (AA) is a hydrogen atom instead of the substituent Z of (AA) The additive for electrolyte solution higher than the oxidation start potential of (BB).

(In the formula, Z, R ¹⁰¹ and R ¹⁰² are organic groups.)
[18] The electrolyte solution additive according to [17], wherein Z is a functional group that is eliminated by oxidation of (AA).
[19] The additive for electrolytic solution according to [17] or [18], wherein the additive (AA) is a nitrogen-containing compound (A) represented by any one of formulas (A1) to (A6).

  According to the electrolyte for nonaqueous secondary batteries and the nonaqueous secondary battery of the present invention, both high overcharge prevention and suppression of deterioration of battery performance can be achieved even when a positive electrode with a high potential is used.

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.

  The electrolyte solution for a non-aqueous secondary battery according to the present invention includes at least one nitrogen-containing compound (A) having a partial structure represented by any one of formulas (A1) to (A6) and a first group of the periodic table. Contains metal ions belonging to Group II or salts thereof and organic solvents.

[Nitrogen-containing compound (A)]
The nitrogen-containing compound (A) has a structure represented by any of the following general formulas (A1) to (A6).

In (A1), X ¹ represents an electron-withdrawing group. The electron-withdrawing group can be defined as a functional group having a positive Hammett σp value, for example, the σp value is preferably 0.2 or more, more preferably 0.3 or more, and further more preferably 0.4 or more. preferable. There is no particular upper limit, but it is practical that it is 2 or less. The greater the σp value, the better the oxidation resistance and the cycle characteristics. Preferred electron withdrawing groups include alkoxycarbonyl groups (preferably having 2 to 10 carbon atoms), acyl groups (preferably having 2 to 10 carbon atoms), acyloxy groups (preferably having 2 to 10 carbon atoms), cyano groups, and sulfonyl groups. It is a group selected from a group (preferably having 1 to 10 carbon atoms) and a halogen-substituted alkyl group (preferably having 1 to 8 carbon atoms).
The sulfonyl group-containing group is preferably an alkylsulfonyl group (preferably having 1 to 10 carbon atoms) or an arylsulfonyl group (preferably having 6 to 10 carbon atoms).

L ¹¹ is a linking group, preferably an aliphatic linking group. More preferably an alkylene group, more preferably an alkylene group having 1 to 3 carbon atoms, particularly preferably _{-CH 2 -, - CH (CH} 3) -, - C (CH 3) 2 -, - CH 2 CH ₂ —, most preferably —CH ₂ —, —CH (CH ₃ ) —, and —C (CH ₃ ) ₂ —. Oxidation resistance is improved by reducing the number of carbon atoms between X ¹ and the nitrogen atom, the cycle property is improved.

Preferred examples of (X ¹ ) _n1 -L ¹¹ -include structures (a1) to (a19) shown below. * Represents a bonding position with a nitrogen atom. In the formulas (a1) to (a19), the alkyl group or the alkylene group part may further have an optional substituent ^Rb . Preferred examples of R ^b are shown in the description of ring Cy below.

In the formula, R ^{301 to} R ³⁰³ are organic groups, preferably an alkyl group (preferably having 1 to 8 carbon atoms, more preferably 1 to 4), and an alkenyl group (preferably having 2 to 8 carbon atoms, more preferably 2). -4, more preferably vinyl group, allyl group), aryl group (preferably 6-10 carbon atoms, more preferably phenyl group), aralkyl group (preferably 7-10 carbon atoms, more preferably benzyl group, phenethyl group). is there. Note that two R ³⁰¹ in one formula may be the same or different.
R ³⁰⁴ is a halogen-substituted alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6), preferably a fluorine-substituted alkyl group, more preferably a trifluoromethyl group.
R ³⁰⁵ represents an organic linking group, preferably an alkane linking group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6), an aryl linking group (preferably having 6 to 22 carbon atoms, more preferably 6 to 14). , An aralkyl linking group (preferably 7 to 23 carbon atoms, more preferably 7 to 15 carbon atoms), an alkenyl linking group (preferably 2 to 12 carbon atoms, more preferably 2 to 6 carbon atoms), or any combination thereof is a single bond. Or it is the coupling group couple | bonded by the coupling group containing a hetero atom. R ³⁰⁵ may further have an optional substituent R ^b .

  n2 represents 1-5. When n2 is 2 or more, the structural parts defined therein may be the same or different from each other. Ph represents a phenyl group.

A combination of preferred (X ¹ ) _n1 -L ¹¹ -and ring Cy formed by L ¹² described later together with a nitrogen atom constitutes a preferred specific example of the present application (A1).

L ¹² has at least one selected from a —C (═O) — bond, carbon-carbon multiple bond, nitrogen-nitrogen single bond or multiple bond, and carbon-nitrogen multiple bond, and forms a ring Cy together with a nitrogen atom. It is a group to do. L ^{12 is> N-L 11 - (X} 1) may further comprise _n1 group.
n1 is an integer of 1 to 3. When n1 is 2 or more, the structures defined there may be the same or different from each other.

The ring structure Cy formed by L ¹² together with the nitrogen atom in (A1) is at least selected from a —C (═O) — bond, a carbon-carbon multiple bond, a nitrogen-nitrogen single bond or a multiple bond, and a carbon-nitrogen multiple bond. have one, -C (= O) - bond (more preferably -C (= O) -N (- *) - binding (- * positions bonded with ^{L 11)),} nitrogen - nitrogen bond Or it is more preferable to have multiple bonds. The ring Cy formed together with the nitrogen atom is preferably a 5-membered ring or a 6-membered ring. Examples of the ring structure Cy formed together with the nitrogen atom include a saturated heterocycle having no multiple bond in the ring and an unsaturated heterocycle having a multiple bond in the ring. The unsaturated heterocycle is resistant to oxidation to a higher potential. Is preferable.

  Examples of the saturated heterocyclic ring include pyrrolidone, piperidone, imidazolidinone, oxazolidone, succinimide, barbituric acid and isocyanuric acid, and succinimide, pyrrolidone, barbituric acid and isocyanuric acid are preferable. Unsaturated heterocycles having multiple bonds in the ring formed with the nitrogen atom include carbazole, imidazole, pyrazole, (di) phenylpyrazole, indole, imidazole, mono, di, triphenylimidazole, benzimidazole, and 2-phenylbenzimidazole. , A heterocyclic structure such as phenoxazine, phenothiazine, indoline, pyrrole, acridone, indazole and triazole is preferable, and a pyrazole structure, a triazole structure and an acridone structure are preferable. These ring structures may be monocyclic or polycyclic structures, but when the ring structure formed with the nitrogen atom is a heteroaromatic ring, from the viewpoint of oxidation resistance, the polycyclic structure is monocyclic or the aromatic ring is not condensed. Is preferred. When a polycyclic structure in which an aromatic ring is condensed is used, it tends to undergo oxidation or reduction and tends to deteriorate cycle characteristics.

The ring Cy formed by L ¹² together with the nitrogen atom is preferably a structure represented by the following formula, and Cy 1 and Cy 2 are particularly preferable. Wherein * represents a bonding position, if * is one, * binds to L ^11. When * is 2 or more, at least one is bonded to L ¹¹ . The remaining * binds to optional substituents R ^a. Preferable examples of R ^a include the substituent T described below, preferably an alkyl group, an aryl group, an alkenyl group, an aralkyl group, an alkoxycarbonyl group, and an acyl group.

These ring structures Cy may have an arbitrary substituent R ^b , and examples of the substituent R ^b include an alkyl group (preferably having 1 to 10 carbon atoms), an aryl group (preferably having 6 to 10 carbon atoms), cyano Group, an alkoxycarbonyl group (preferably having 2 to 10 carbon atoms) and a sulfonyl group-containing group (preferably having 1 to 10 carbon atoms) are preferred. Moreover, when substituted with an electron withdrawing group, oxidation resistance improves. The sulfonyl group-containing group is preferably an alkylsulfonyl group (preferably having 1 to 10 carbon atoms) or an arylsulfonyl group (preferably having 6 to 10 carbon atoms).

Preferable specific examples of the ring Cy formed by L ¹² together with the nitrogen atom are described below.
* Represents a bonding position, * if one, * binds to ^{L 11.} When * is 2 or more, at least one is bonded to L ¹¹ . The remaining * binds to optional substituents R ^a.

  Specific examples of the compound represented by Formula A1 are listed below.

（Ａ２）中、Ｒ^２１は置換基でありアルキル基（好ましくは炭素数１〜８、より好ましくは１〜４）、アルケニル基（好ましくは炭素数２〜８、より好ましくは１〜４、更に好ましくはビニル基、アリル基）、アリール基（好ましくは炭素数６〜１０、より好ましくフェニル基）、アラルキル基（好ましくは炭素数７〜１０、より好ましくベンジル基、フェネチル基）、アルコキシ基（好ましくは炭素数１〜８、より好ましくは１〜４）、アリールオキシ基（好ましくは炭素数６〜１０、より好ましくフェノキシ基）、含窒素基（好ましくはアルキル基またはアリール置換されたアミノ基を有する基であり、窒素原子とＬ^１２が環を形成した基であることがより好ましい）が好ましい。

In (A2), R ²¹ is a substituent, an alkyl group (preferably having 1 to 8 carbon atoms, more preferably 1 to 4), an alkenyl group (preferably having 2 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, and further, Preferably vinyl group, allyl group), aryl group (preferably 6-10 carbon atoms, more preferably phenyl group), aralkyl group (preferably 7-10 carbon atoms, more preferably benzyl group, phenethyl group), alkoxy group (preferably Has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, an aryloxy group (preferably 6 to 10 carbon atoms, more preferably a phenoxy group), a nitrogen-containing group (preferably an alkyl group or an aryl-substituted amino group). And a group in which a nitrogen atom and L ¹² form a ring is more preferable.

Preferred specific examples of R ²¹ are shown below. Me is a methyl group, Ec is an ethyl group, tBu is a t-butyl group, and Ph is a phenyl group. The same applies hereinafter.

L ¹² has the same meaning as L ¹² in (A1). L ¹² may further contain a> N—C (═O) —R ²¹ group in the ring.
A preferable specific example of ring Cy formed together with these preferable R ²¹ and nitrogen atom, or any combination thereof constitutes a preferable specific example of the compound (A2) of the present application.

Specific examples of preferred (A2) are shown below.

[In (A3), L ³¹ represents —S (═O) — or —S (═O) ₂ —, and —S (═O) ₂ — is preferred from the viewpoint of oxidation resistance. R ³¹ and R ³² are each an alkyl group (preferably having 1 to 8 carbon atoms, more preferably 1 to 4), an aryl group (preferably 6 to 10 carbon atoms, more preferably a phenyl group), a heteroaryl group (carbon number). 1 to 12 is preferable, and 2 to 5 is more preferable, preferably a nitrogen-containing heteroaryl group, preferably 5 or 6 members, and an aralkyl group (preferably having 7 to 10 carbon atoms, More preferably benzyl group, phenethyl group), alkylsulfonyl group (preferably 1-8 carbon atoms, more preferably 1-4), arylsulfonyl group (preferably 6-10 carbon atoms), acyl group (preferably carbon number). 2-8), alkoxycarbonyl groups (preferably 2 to 8 carbon atoms), or an ^-L 31 ^{-R 33.} R ³¹ and R ³² may be bonded or condensed to form a ring Cy together with the nitrogen atom. Ring Cy has the same meaning as Ring Cy in (A1). Further in the ring Cy may include ^-L 31 ^{-R 33.} R ³³ is an alkyl group (preferably having 1 to 8 carbon atoms, more preferably 1 to 4), an alkenyl group (preferably having 2 to 8 carbon atoms, more preferably 1 to 4, still more preferably vinyl or allyl groups), An aryl group (preferably having a carbon number of 6 to 10, more preferably a phenyl group), an aralkyl group (preferably having a carbon number of 7 to 10, more preferably a benzyl group or a phenethyl group), an alkoxy group (preferably having a carbon number of 1 to 8, more preferably 1 to 4), an aryloxy group (preferably 6 to 10 carbon atoms, more preferably a phenoxy group), a nitrogen-containing group (preferably an alkyl group or an aryl-substituted amino group, and —NR ³¹ R ³² is more preferable. ). However, at least one of R ³¹ and R ³² is an aryl group, or R ³¹ and R ³² are bonded or condensed to form a ring Cy together with a nitrogen atom. ]

Preferred examples of (A3) are shown below.

In (A4), R ⁴¹ and R ⁴² are each an alkyl group (preferably having 1 to 8 carbon atoms, more preferably 1 to 4), an aryl group (preferably having 6 to 10 carbon atoms, more preferably a phenyl group), and heteroaryl. A group (preferably having 1 to 12 carbon atoms, more preferably 2 to 5; preferably a nitrogen-containing heteroaryl group; preferably having 5 or 6 members), an aralkyl group (preferably having a carbon number). 7-10, more preferably benzyl group, phenethyl group), alkylsulfonyl group (preferably 1-8 carbon atoms, more preferably 1-4), arylsulfonyl group (preferably 6-10 carbon atoms), acyl group (preferably carbon atoms 2-8), an alkoxycarbonyl group of (preferably 2 to 8 carbon atoms), or a phosphorus-containing group ^{(-P (= O) R 43} R 44 are preferred) It is. R ⁴¹ and R ⁴² may be bonded or condensed to form a ring Cy together with the nitrogen atom. Ring Cy has the same meaning as Ring Cy in (A1). When the ring Cy further contains a nitrogen atom, a phosphorus-containing group (—P (═O) R ⁴³ R ⁴⁴ ) may be bonded or condensed on the nitrogen atom. However, at least one of R ⁴¹ and R ⁴² is an aryl group, or R ⁴¹ and R ⁴² are bonded or condensed to form a ring Cy together with a nitrogen atom.
R ⁴³ and R ⁴⁴ are each an alkyl group (preferably having 1 to 8 carbon atoms), an aryl group (preferably having 1 to 8 carbon atoms), an aralkyl group (preferably having 7 to 11 carbon atoms), an alkoxy group (preferably having a carbon number). 1 to 8), an aryloxy group (preferably 6 to 10 carbon atoms, more preferably a phenoxy group), an aralkyloxy group (preferably 7 to 11 carbon atoms, more preferably a benzyloxy group), a halogen atom (preferably fluorine). Atom), a nitrogen-containing group (preferably an alkyl-substituted and / or aryl-substituted amino group, more preferably —NR ⁴¹ R ⁴² ).

Preferred examples of (A4) are shown below.

In (A5), R ⁵¹ and R ⁵² are each an alkyl group (preferably having 1 to 8 carbon atoms, more preferably 1 to 4), an aryl group (preferably having 6 to 10 carbon atoms, more preferably a phenyl group), and heteroaryl. A group (preferably having 1 to 12 carbon atoms, more preferably 2 to 5; preferably a nitrogen-containing heteroaryl group; preferably having 5 or 6 members), an aralkyl group (preferably having a carbon number). 7-10, more preferably benzyl group, phenethyl group), alkylsulfonyl group (preferably 1-8 carbon atoms, more preferably 1-4), arylsulfonyl group (preferably 6-10 carbon atoms), acyl group (preferably Is a C2-C8) or alkoxycarbonyl group (preferably C2-C8). R ⁵¹ and R ⁵² may be bonded or condensed to form a ring Cy together with the nitrogen atom. Ring Cy has the same meaning as Ring Cy in (A1). When the ring Cy further contains a nitrogen atom, —SiR ⁵³ R ⁵⁴ R ⁵⁵ may be bonded to the nitrogen atom. However, at least one of R ⁵¹ and R ⁵² is an aryl group, or R ⁵¹ and R ⁵² are bonded or condensed to form a ring structure together with a nitrogen atom.
R ^{53 to} R ⁵⁵ are each a hydrogen atom, an alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6), an aryl group (preferably having 6 to 22 carbon atoms, more preferably 6 to 14), and an aralkyl group. (C7-23 is preferable, and 7-15 are more preferable) and nitrogen-containing groups (C1-12 are preferable, and 2-5 are more preferable). The nitrogen-containing group is preferably —NR ⁵¹ R ⁵² , and more preferably forms a ring Cy together with a nitrogen atom.

Preferred examples of (A5) are shown below.

In (A6), R ⁶¹ and R ⁶² are alkyl groups (preferably having 1 to 8 carbon atoms, more preferably 1 to 4), aryl groups (preferably having 6 to 10 carbon atoms, more preferably phenyl groups), heteroaryl groups. (C1-C12 is preferable, 2-5 is more preferable. It is preferable that it is a nitrogen-containing heteroaryl group. It is preferable that it is between 5 or 6 members.), An aralkyl group (preferably C7). -10, more preferably benzyl group, phenethyl group), alkylsulfonyl group (preferably 1-8 carbon atoms, more preferably 1-4), arylsulfonyl group (preferably 6-10 carbon atoms), acyl group (preferably C2-C8) or an alkoxycarbonyl group (preferably C2-C8). R ⁶¹ and R ⁶² may be bonded or condensed to form a ring Cy together with the nitrogen atom. Ring Cy has the same meaning as Ring Cy in (A1). R ⁶³ is a hydrogen atom, an alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6), an aryl group (preferably having 6 to 22 carbon atoms, more preferably 6 to 14), or an aralkyl group (having carbon numbers). 7-23 are preferable, and 7-15 are more preferable.
n6 represents 2-4.

Preferred examples of (A6) are shown below.

  The nitrogen-containing compound (A) may have two or more partial structures represented by (A1) to (A6) in one molecule. In other words, the nitrogen-containing compound (A) may be a multimer (preferably a dimer) linked at any position of (A1) to (A6).

  The oxidation start of the nitrogen-containing compound (A) is preferably at a potential of 4.4V to 5.5V (vs. Li / Li +) or more, more preferably 4.5V to 5V. By setting the oxidation start potential within a specific range, it can function quickly during overcharge without reacting at the normal charge potential.

The oxidation initiation potential of each compound is shown below. The measurement method was to prepare an electrolyte solution by dissolving a nitrogen-containing compound at a concentration of 1% by mass in a solution obtained by dissolving LiPF ₆ in ethylene carbonate / ethyl methyl carbonate (volume ratio 3/7) at a concentration of 1M. Oxidation of this electrolytic solution was started at Hokuto Denko Co., Ltd. electrochemical measuring device (trade name: VMP-3), where a larger current value was observed than the electrolytic solution to which no additive was added by the cyclic voltammogram method. The potential (vs. Li / Li +) was set (measurement conditions were: working electrode: glassy carbon, reference electrode: Li metal, counter electrode: Li metal, scanning speed: 5 mA / s).

  By having a specific functional group, compared with an NH compound having no specific functional group, oxidation does not occur up to a high potential and high oxidation resistance can be imparted.

Another embodiment of the present invention includes the following means. An electrolyte solution for a non-aqueous secondary battery containing an additive represented by the formula (AA), wherein the oxidation start potential of (AA) is a hydrogen atom instead of the substituent Z of (AA) ( An electrolyte higher than the oxidation start potential of BB).

  Z is an organic group, preferably a group represented by the following formula.

R ¹⁰¹ and R ¹⁰² are organic groups. Preferable examples of R ¹⁰¹ and R ¹⁰² include the examples of R ³¹ and R ³² described above. In the formulas (Z-1) to (Z-5), X ¹ , L ¹¹ , R ²¹ , R ³³ , L ³¹ , R ⁴³ , R ⁴⁴ , R ^{53 to} R ⁵⁵ are represented by the formulas (A1) to (A5). It is synonymous with. The preferable thing is also the same.
When Z is a functional group that is eliminated by oxidation of (AA), the high oxidation resistance and the active species eliminated by oxidation can achieve both high reactivity similar to that of the NH form. As the compound (AA), the aforementioned nitrogen-containing compound (A) is particularly preferable.

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.

  The addition amount of the compound (A) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, further preferably 0.1% by mass or more, and particularly preferably 0.5% by mass or more in the total electrolyte solution. It is. The upper limit is preferably 10% by mass or less, more preferably 7% by mass or less, further preferably 5% by mass or less, and particularly preferably 3% by mass or less. By selecting a suitable addition amount, both safety during overcharge and battery characteristics during normal use can be achieved.

(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.

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.
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)>
As a halogen atom which a halogen-containing compound has, a fluorine atom, a chlorine atom, or a bromine atom is preferable, and a fluorine atom is more preferable. 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)>
As the polymerizable compound, a compound having a carbon-carbon double bond is preferable, and a group selected from a carbonate compound having a double bond such as vinylene carbonate and vinyl ethylene carbonate, an acrylate group, a methacrylate group, a cyanoacrylate group, and an αCF3 acrylate group. And a compound having a styryl group are preferred, and a carbonate compound having a double bond or a compound having two or more polymerizable groups in the molecule is more preferred.

<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, and tribenzyl phosphate. As the phosphorus-containing compound, a compound represented by the following formula (D2) or (D3) is also 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.

  The electrolytic solution of the present invention may contain at least one selected from the above-mentioned (A) to (G), a negative electrode film forming agent, a flame retardant, an overcharge inhibitor and the like. Although the content rate of these functional additives in a non-aqueous electrolyte solution does not have limitation in particular, 0.001 mass%-10 mass% are preferable with respect to the whole non-aqueous electrolyte solution, respectively. 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 metal ion belonging to Group 1 or Group 2 of the periodic table or a salt thereof, and 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 ) ₂ is preferred, such as LiPF ₆ , LiBF ₄ , LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ) ₂ The lithium imide salt is more preferable. 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 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.

[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. The nonaqueous secondary battery of the present invention includes at least the electrolyte solution for a nonaqueous battery of the present invention as an electrolytic solution.

(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 You may use a particulate positive electrode active material for a positive electrode active material. Specifically, a transition metal oxide capable of reversibly inserting and releasing lithium ions can be used, but a lithium-containing transition metal oxide is preferably used. Preferred examples of the lithium-containing transition metal oxide preferably used as the positive electrode active material include oxides containing lithium-containing Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, and W. Alkali metals other than lithium (elements of Group 1 (Ia) and Group 2 (IIa) of the periodic table) and / or Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P , B, etc. may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.

  Among the lithium-containing transition metal oxides preferably used as the positive electrode active material, a lithium compound / transition metal compound (wherein the transition metal is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, W) It is more preferable that the mixture is synthesized so that the total molar ratio of the compound is 0.3 to 2.2.

Further, among the lithium compounds / transition metal compounds, Li _g M3O ₂ (M3 represents one or more elements selected from Co, Ni, Fe, and Mn. G represents 0 to 1.2. ) Or a material having a spinel structure represented by Li _h M4 ₂ O (M4 represents Mn. H represents 0 to 2). As M3 and M4, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B may be mixed in addition to the transition metal. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.

The _Li g M3O material containing _2, among the materials having the spinel structure represented by _{Li h M4 2 O, Li g} CoO 2, Li g NiO 2, Li g MnO 2, Li g Co j Ni 1-j O _{2, Li h Mn 2 O 4} , LiNi j Mn 1-j O 2, LiCo j Ni h Al 1-j-h O 2, LiCo j Ni h Mn 1-j-h O 2, LiMn h Al 2-h O ₄ , LiMn _h Ni _{2 -h} O ₄ (where g represents 0.02 to 1.2, j represents 0.1 to 0.9, and h represents 0 to 2) is particularly preferable. , most preferably _{Li g CoO 2, LiMn 2 O} 4, LiNi 0.85 Co 0.01 Al 0.05 O 2, and is _{LiNi 0.33 Co 0.33 Mn 0.33 O 2} . Of these, an electrode containing Ni is more preferable from the viewpoint of high capacity and high output. Here, the g value and the h value are values before the start of charge / discharge, and are values that increase / decrease due to charge / discharge. In particular,
LiCoO ₂ , LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.01 Al _0.05 O ₂ ,
LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiMn _1.8 Al _0.2 O ₄ ,
LiMn _1.5 Ni _0.5 O ₄ and the like.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples include, for example, LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ). ₃ , iron phosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other metals.

In the nonaqueous 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.

-Positive electrode active material In this invention, it is preferable to use the material which can maintain normal use with the positive electrode potential (Li / Li ⁺ reference | standard) of 4.25V or more for a positive electrode active material. 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. This potential may be simply referred to as a positive electrode potential. The positive electrode potential (usually usable potential) is more preferably 4.3 V or more. Although there is no upper limit in particular, it is practical that it is 5V or less.

Examples of the positive electrode active material having the specific electrode potential include the following.
(I) LiNi _x Mn _y Co _z O ₂ (x> 0.2, y> 0.2, z ≧ 0, x + y + z = 1),
Representative:
LiNi _1/3 Mn _1/3 Co _1/3 O ₂ (also described as LiNi _0.33 Mn _0.33 Co _0.33 O ₂ )
LiNi _1/2 Mn _1/2 O ₂ (also described as LiNi _0.5 Mn _0.5 O ₂ )
(Ii) LiNi _x Co _y Al _z O ₂ (x> 0.7, y> 0.1, 0.1>z> 0.05, x + y + z = 1)
Representative:
LiNi _0.8 Co _0.15 Al _0.05 O ₂

The following can also be used as the positive electrode active material having the specific electrode potential.
(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

In the non-aqueous electrolyte secondary battery of the present invention, a particulate positive electrode active material may be used. 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.

A pulverizer or a classifier commonly used to make the positive electrode active substance have a predetermined particle size can be 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.
[Measurement method of electrode potential (Li / Li ⁺ reference)]
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 is used as the negative electrode, the negative electrode potential is 0.1V. The battery voltage is observed during charging and the positive electrode potential is calculated.

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

・ Negative electrode active material The negative electrode active material is not particularly limited as long as it can reversibly insert and release lithium ions. Carbonaceous materials, metal oxides such as tin oxide and silicon oxide, metal composite oxides, Examples thereof include lithium alloys such as lithium alone and lithium aluminum alloys, and metals capable of forming an alloy with lithium such as Sn and Si.
These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. 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.

  The metal oxide and metal composite oxide which are negative electrode active materials used in the non-aqueous secondary battery of the present invention may contain at least one of them. As the metal oxide and metal complex oxide, amorphous oxide is particularly preferable, and chalcogenite, which is a reaction product of a metal element and an element of Group 16 of the periodic table, is also preferably used. The term “amorphous” as used herein means an X-ray diffraction method using CuKα rays, which has a broad scattering band having an apex in the region of 20 ° to 40 ° in terms of 2θ values, and is a crystalline diffraction line. You may have. The strongest intensity of crystalline diffraction lines seen from 2 ° to 40 ° to 70 ° is 100 times the diffraction line intensity at the peak of the broad scattering band seen from 2 ° to 20 °. It is preferable that it is 5 times or less, and it is particularly preferable not to have a crystalline diffraction line.

Among the compound group consisting of the amorphous oxide and the chalcogenide, an amorphous oxide of a metalloid element and a chalcogenide are more preferable, and elements of Groups 13 (IIIB) to 15 (VB) of the periodic table, Particularly preferred are oxides and chalcogenides composed of one kind of Al, Ga, Si, Sn, Ge, Pb, Sb, Bi or a combination of two or more kinds thereof. Specific examples of preferable amorphous oxides and chalcogenides include, for example, Ga ₂ O ₃ , SiO, GeO, SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , SnSiO ₃ , GeS, SnS, SnS ₂ , PbS, PbS ₂ , Sb ₂ S ₃ , Sb ₂ S ₅ , such as SnSiS ₃ may preferably be mentioned. Moreover, these may be a complex oxide with lithium oxide, for example, Li ₂ SnO ₂ .

  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, as the negative electrode active material that can be used in combination with the amorphous oxide negative electrode active material centering on Sn, Si, Ge, a carbon material capable of inserting and extracting lithium ions or lithium metal, lithium, Preferred examples include lithium alloys and metals that can be alloyed with lithium.

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). Further, metal or metal oxide negative electrodes (preferably Si, Si oxide, Si / Si oxide, Sn, Sn oxide, SnB _x P _y O _z , Cu, which can be alloyed with lithium, which are being developed for higher capacity) / Sn and a plurality of these composites), and a battery using a composite of these metals or metal oxides and a carbon material as a negative electrode.

In the present invention, it is also preferable to use lithium titanate, more specifically, lithium-titanium oxide (Li [Li _1/3 Ti _5/3 ] O ₄ ) as the negative electrode active material. By using this as the negative electrode active material, the effect of the electrolytic solution of the present invention is further enhanced, and more excellent battery performance can be exhibited.

-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 current collector, 26 is a gasket, 28 is a pressure-sensitive valve element, 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.

[Electrode potential and resistance increase rate]
In the electrolytic solution or secondary battery of the present invention, it is preferable that the specific compound does not act below the normal charge potential of the battery. Specifically, the normal charge positive electrode potential (positive electrode potential of the positive electrode active material) of this battery is preferably 4.25 V (Li / Li ⁺ reference) or more, and more preferably 4.3 V or more. Although there is no upper limit in particular, it is practical that it is 5V or less. Further, the rate of increase in resistance calculated by impedance measurement is preferably 5 or more, and more preferably 15 or more. There is no particular upper limit, but it is preferably 1000 or less. Note that the rate of increase in resistance by the above impedance measurement can also characterize the present invention as a performance when a secondary battery is obtained.

[Measurement method of resistance increase rate]
As a method for observing the resistance of the battery, there is a method for measuring the AC impedance of the battery. When the frequency is changed from a low frequency to a high frequency and the change in impedance at that time is plotted on a complex plane, the resistance of the battery can be measured by obtaining a graph called “Cole-Cole Plot”. The rate of increase in resistance is obtained from the resistance when overcharged and the resistance when charged at a normal potential. The specific measurement method can refer to those employed in the examples.

  Here, when the definition of terms is confirmed, normal charging means a state in which 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]
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.

  The application mode of the electrolyte solution for a non-aqueous secondary battery of the present invention is not limited, but high capacity and high rate discharge characteristics are required particularly from the viewpoint of exerting the advantages of safety during overcharge and high rate discharge characteristics. It is preferable to be applied to an application. 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 and the like are equipped with a high-capacity secondary battery and are expected to be charged every day at home, and further safety is required against overcharging. 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.

<Example 1 and Comparative Example 1>
Preparation of electrolytic solution for battery (1) The component (A) is added to the solvent shown in Table 1 in the amount shown in the table, and the electrolyte LiPF ₆ or LiBF ₄ is dissolved to 1 M. A liquid was prepared. All the prepared electrolyte solutions had a viscosity at 25 ° C. of 5 mPa · s or less, and the water content measured by the Karl Fischer method (JIS K0113) was 20 ppm or less. The compounds used in the table are as follows.

Me: methyl group Et: ethyl group Ph: phenyl group tBu: t-butyl group

Solvent (volume ratio)
S1: Ethylene carbonate / methyl ethyl carbonate (3/7)
S2: ethylene carbonate / propylene carbonate / γ-butyrolactone (1/1/2)
S3: ethylene carbonate / diethyl carbonate / methyl ethyl carbonate (1/1/1)

<Production of battery (1)>
The positive electrode is made of active material: nickel manganese lithium cobaltate (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ) 85% by mass, conductive auxiliary agent: carbon black 7% by mass, binder: PVDF 8% by mass, The negative electrode was prepared with 94% by mass of active material: lithium titanate (Li ₄ Ti ₅ O ₁₂ ), conductive auxiliary agent: 3% by mass of carbon black, and binder: 3% by mass of PVDF. The separator is made of cellulose and has a thickness of 50 μm. Using the above positive and negative electrodes and separator, a 2032 type coin battery was produced for each test electrolyte and initialized under the following conditions.

<Battery initialization>
Charged at a constant current of 0.2 C until the battery voltage becomes 2.55 V (positive electrode potential 4.1 V) in a thermostat at 30 ° C., and then charged until the battery voltage reaches a current value of 0.12 mA at a constant voltage of 2.55 V. Went. However, the upper limit of the time was 2 hours. Next, 0.2C constant current discharge was performed until the battery voltage became 1.2V in a 30 degreeC thermostat. This operation was repeated twice. Since the operating potential of the lithium titanate negative electrode is 1.55V, the battery voltage is a value obtained by subtracting 1.55V from the positive electrode potential. The following items were evaluated using the 2032 type battery produced by the above method. The results are shown in Table 1.

<Overcharge test>
After charging with constant current 2 mA (1 C) in a constant temperature bath at 30 ° C. using a 2032 battery produced by the above method until the positive electrode potential becomes 4.1 V as a normal potential test, constant voltage charging is performed for 2 hours. The resistance was measured by impedance measurement. After that, as an overcharge test, the battery was charged at a constant current of 2 mA (1 C) until the positive electrode potential reached 5 V, and then charged at a constant voltage for 2 hours, and the resistance was measured by impedance measurement. Calculated by the formula. The larger the value, the larger the resistance increase at the time of overcharging, which means that the excessive release of lithium ions from the positive electrode can be suppressed.
Resistance increase rate = (resistance at 5V / resistance at 4.1V)

In the overcharge test, the resistance increase rate was evaluated as follows.
AA: 20 or more A: 15 or more and less than 20 B: 5 or more and less than 15 C: Less than 5

<Battery performance deterioration test during normal use>
The deterioration of the battery performance when used at the positive electrode potential of 4.1 V, 4.25 V and 4.35 V as normal use was tested by the following method.

<4.1V discharge capacity maintenance rate>
<4.1V / initial 4C discharge capacity>
The battery after initialization was charged at a constant current of 0.2 C in a 45 ° C. constant temperature bath until the battery voltage reached 2.55 V (positive electrode potential 4.1 V), and then the current value was adjusted to 0.12 mA at a constant voltage of 2.55 V. The battery was charged until However, the upper limit of the time was 2 hours. Next, in a 45 ° C. thermostat, 4C constant current discharge was performed until the battery voltage reached 1.2V, and the initial discharge capacity (I) at a positive electrode potential of 4.1V was measured.

<4.1V discharge capacity after cycle test>
This battery was charged in a constant temperature bath at 45 ° C. until the battery voltage reached 2.55 V (positive electrode potential 4.1 V), and then charged at 2.55 V constant voltage until the current value reached 0.12 mA. It was. However, the upper limit of the time was 2 hours. Next, 1C constant current discharge was performed until the battery voltage reached 1.2 V, and one cycle was obtained. This was repeated until 200 cycles were reached. Thereafter, the same measurement as the initial 4C discharge capacity (I) was performed, and the 4C discharge capacity (II) after the cycle test was measured. The discharge capacity retention rate (4.1 V) before and after the cycle test was calculated from the following formula. The larger the value, the smaller the capacity deterioration at the time of large current discharge (4C) even if charging / discharging is repeated, which is good.
Discharge capacity maintenance rate (4.1 V) = (II) / (I)

<4.25V / 4C discharge capacity maintenance ratio>
Except that the battery voltage at the time of charging was set to 2.7V (positive electrode potential 4.25V), a test similar to the measurement of the 4.1V / 4C discharge capacity was performed, and 4.25V / initial 4C discharge capacity (III), And 4.25V / 4C discharge capacity (IV) after the cycle test was measured. The discharge capacity retention ratio (4.25 V) before and after the cycle test was calculated from the following formula. The larger the value, the smaller the capacity deterioration at the time of large current discharge (4C) even if charging / discharging is repeated, which is good.
Discharge capacity maintenance ratio (4.25V) = (IV) / (III)

<4.35V / 4C discharge capacity maintenance ratio>
A test similar to the measurement of 4.1V / 4C discharge capacity was performed except that the battery voltage during charging was 2.8V (positive electrode potential 4.35V), and 4.35V / initial 4C discharge capacity (V), And the 4.35V / 4C discharge capacity (VI) after the cycle test was measured. The discharge capacity retention ratio (4.35 V) before and after the cycle test was calculated from the following formula. The larger the value, the smaller the capacity deterioration at the time of large current discharge (4C) even if charging / discharging is repeated, which is good.
Discharge capacity maintenance ratio (4.35V) = (VI) / (V)

  A higher capacity retention rate when using a higher battery voltage (positive electrode potential) is preferable because the battery capacity can be increased.

The results of the discharge capacity retention rate were evaluated as follows.
AA: 0.9 or more A: 0.8 or more and less than 0.9 B: 0.7 or more and less than 0.8 C: 0.5 or more and less than 0.7 D: Less than 0.5

Test No. : A sample starting with “c” is a comparative example, and the others are examples of the present invention.

<Example 2 and Comparative Example 2>
-Preparation of Electrolytic Solution Compound (A) was dissolved in 1M-LiPF ₆ solution using the solvents shown in Table 2 at the concentrations shown in the table to prepare electrolytic solutions for examples and comparative examples. . All the prepared electrolyte solutions had a viscosity at 25 ° C. of 5 mPa · s or less.

-Production of battery (2) The positive electrode was produced with 85% by mass of an active material: lithium manganate (LiMn ₂ O ₄ ), conductive auxiliary agent: 7% by mass of carbon black, binder: 8% by mass of PVDF, Material: 86% by mass of graphite, conductive assistant: 6% by mass of carbon black, binder: 8% by mass of PVDF. The separator was replaced with a polypropylene 25 μm thickness. Using the above positive and negative electrodes and separator, each test No. With respect to the electrolytic solution, a 2032 type coin battery was prepared and the following items were evaluated. The results are shown in Table 2.

<Battery initialization>
The battery was charged at a constant current of 0.2 C until the positive electrode potential reached 4.1 V in a thermostat at 30 ° C., and then charged until the current value reached 0.12 mA at a positive electrode potential of 4.1 V constant voltage. However, the upper limit of the time was 2 hours. Next, 0.2 C constant current discharge was performed until the battery voltage became 2.75 V in a 30 ° C. constant temperature bath. This operation was repeated twice.

  The following items were evaluated using the 2032 type battery produced by the above method. The results are shown in Table 2.

<Overcharge test>
After charging with constant current 2 mA (1 C) in a constant temperature bath at 30 ° C. using a 2032 battery produced by the above method until the positive electrode potential becomes 4.1 V as a normal potential test, constant voltage charging is performed for 2 hours. The resistance was measured by impedance measurement. Then, it charged with constant current 2mA (1C) until the positive electrode electric potential became 5V as an overcharge test. Subsequently, constant voltage charge was performed for 2 hours, resistance was measured by impedance measurement, and the rate of increase in resistance during overcharge was calculated by the following equation. The larger the value, the larger the resistance increase at the time of overcharging, which means that the excessive release of lithium ions from the positive electrode can be suppressed.
Resistance increase rate = (resistance at 5V / resistance at 4.1V)

In the overcharge test, the resistance increase rate was evaluated as follows.
AA: 20 or more A: 15 or more and less than 20 B: 5 or more and less than 15 C: Less than 5

<Battery performance deterioration test during normal use>
The following method was used to test the deterioration of battery performance when used at a positive electrode potential of 4.1 V and 4.25 V during normal use.

<4.1V / 4C discharge capacity maintenance rate>
<4.1V / initial 4C discharge capacity>
The battery after initialization was charged at a constant current of 0.2 C until the positive electrode potential reached 4.1 V in a thermostatic chamber at 30 ° C., and then charged at a constant voltage of 4.1 V until the current value reached 0.12 mA. However, the upper limit of the time was 2 hours. Next, 4C constant current discharge was performed until the battery voltage became 2.75V in a 30 ° C constant temperature bath, and the initial 4C discharge capacity (VII) at 4.1V was measured.
<4.1V / 4C discharge capacity after cycle test>
This battery was charged at a constant current of 1 C in a thermostat at 30 ° C. until the positive electrode potential reached 4.1 V, and then charged at a constant voltage of 4.1 V until the current value reached 0.12 mA. However, the upper limit of the time was 2 hours. Next, 1C constant current discharge was performed until the battery voltage reached 2.75 V, and one cycle was obtained. This was repeated until 300 cycles were reached. Thereafter, the same measurement as the initial 4C discharge capacity (VII) was performed, and the 4.1 V / 4C discharge capacity (VIII) after the cycle test was measured. The discharge capacity retention rate (4.1 V) before and after the cycle test was calculated from the following formula. The larger the value, the smaller the capacity deterioration at the time of large current discharge (4C) even if charging / discharging is repeated, which is good.
Discharge capacity maintenance ratio (4.1V) = (VIII) / (VII)

<4.25V / 4C discharge capacity maintenance ratio>
A test similar to the measurement of the 4.1 V / 4C discharge capacity was performed except that the positive electrode potential at the time of charging was set to 4.25 V. 4.25 V / initial 4 C discharge capacity (IX) The 25V / 4C discharge capacity (X) was measured. The discharge capacity retention ratio (4.25 V) before and after the cycle test was calculated from the following formula. The larger the value, the smaller the capacity deterioration at the time of large current discharge (4C) even if charging / discharging is repeated, which is good.
Discharge capacity maintenance ratio (4.25V) = (X) / (IX)

The results of the discharge capacity retention rate were evaluated as follows.
AA: 0.9 or more A: 0.8 or more and less than 0.9 B: 0.7 or more and less than 0.8 C: 0.5 or more and less than 0.7 D: Less than 0.5

Test No. : A sample starting with “c” is a comparative example, and the others are examples of the present invention.

  When the electrolytic solution of the present invention is used, in addition to safety during overcharging, cycle characteristics are excellent even when charging and discharging are performed at a higher potential.

<Example 3 and Comparative Example 3>
When the discharge capacity retention rate was calculated under the same conditions as in Example 2 and Comparative Example 2 by replacing the positive electrode active material with lithium cobalt oxide, the electrolyte solution of the present application was compared with the electrolyte solution of the comparative example, as in Example 2. It was excellent in the overcharge characteristics and little deterioration of the large current discharge characteristics before and after the cycle test.

In the above examples, the lithium electrolyte of the present invention is used as a negative electrode and a lithium / titanium oxide negative electrode or a carbon material negative electrode, and a battery using a nickel manganese lithium lithium cobaltate, lithium cobaltate, or lithium manganate as a positive electrode exhibits excellent characteristics. From this result, it was shown that the electrolyte of the present invention is a metal or metal oxide negative electrode (preferably Si, Si oxide, Si / Si oxide) capable of forming an alloy with lithium, which is being developed for higher capacity. , Sn, Sn oxide, SnB _x P _y O _z , Cu / Sn, and a plurality of these composites), a battery using a composite of these metals or metal oxides and a carbon material, or LiFePO _4, etc. The same excellent effect can be obtained in batteries using an olivine-based positive electrode or a positive electrode used at a potential of 4.5 V or more. It can be assumed that it is expressed.

Claims (19)

At least one nitrogen-containing compound (A) having a structure represented by any one of the following formulas (A1) to (A6), a metal ion belonging to Group 1 or Group 2 of the periodic table or a salt thereof, and an organic solvent An electrolyte for a non-aqueous secondary battery.

[In (A1), X ¹ represents an electron-withdrawing group. L ¹¹ represents a linking group. L ¹² has at least one selected from —C (═O) — bond, carbon-carbon multiple bond, nitrogen-nitrogen single bond or multiple bond, and carbon-nitrogen multiple bond, and forms a ring Cy together with a nitrogen atom. Represents a group. L ^{12 is> N-L 11 - (X} 1) may further comprise _n1 group. n1 represents an integer of 1 to 3. ]
[In (A2), R ²¹ represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an aralkyl group, an alkenyl group, or a nitrogen-containing group. L ¹² has the same meaning as ^{L 12} in (A1). L ¹² may further include a> N—C (═O) —R ²¹ group. ]
[In (A3), L ³¹ represents —S (═O) — or —S (═O) ₂ —. R ³¹ and R ³² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an alkoxycarbonyl group, or —L ³¹ —R ³³ . R ³¹ and R ³² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ³³ represents an alkyl group, an aryl group, an aralkyl group, or a nitrogen-containing group. However, at least one of R ³¹ and R ³² is an aryl group or a heteroaryl group, or R ³¹ and R ³² are bonded or condensed to form a ring structure Cy together with a nitrogen atom. ]
[In (A4), R ⁴¹ and R ⁴² each represent an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an alkoxycarbonyl group, or a phosphorus-containing group. R ⁴¹ and R ⁴² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ⁴³ and R ⁴⁴ each represents an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, an aralkyloxy group, a halogen atom, or a nitrogen-containing group. However, at least one of R ⁴¹ and R ⁴² is an aryl group, or R ⁴¹ and R ⁴² are bonded or condensed to form a ring structure with a nitrogen atom. ]
[In (A5), R ⁵¹ and R ⁵² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, or an acyl group. R ⁵¹ and R ⁵² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ^{53 to} R ⁵⁵ each represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a nitrogen-containing group. However, at least one of R ⁵¹ and R ⁵² is an aryl group, or R ⁵¹ and R ⁵² are bonded or condensed to form a ring structure together with a nitrogen atom. ]
[In (A6), R ⁶¹ and R ⁶² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, or an acyl group. R ⁶¹ and R ⁶² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ⁶³ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. n6 represents 2-4. ]
[The nitrogen-containing compound (A) may be a multimer linked at any position of (A1) to (A6). ] The electrolyte solution for a non-aqueous secondary battery according to claim 1, wherein the ring structure formed by L ¹² together with the nitrogen atom contains a —C (═O) — bond, a nitrogen-nitrogen single bond, or a multiple bond. L ¹² represents a non-aqueous liquid electrolyte for a secondary battery (where * is bonding position of claim 1 or 2 ring structure is a structure represented by the following formula to form together with the nitrogen atom, * is one If, If * binds to L ^11. * is two or more, at least one binding to L ^11. the remaining * is bonded to hydrogen atom or an arbitrary substituent R ^a. a hydrogen atom in the formula is (It may be substituted with any substituent R ^b )

The electrolyte solution for a non-aqueous secondary battery according to claim 1 or 2, wherein L ¹¹ is an alkylene group having 1 to 3 carbon atoms. X ¹ is an alkoxycarbonyl group, an acyl group, an acyloxy group, a cyano group, a sulfonyl group-containing group, and a non-aqueous liquid electrolyte for a secondary battery according to any one of claims 1 to 4, selected from a halogen-substituted alkyl group .   Further, the compound different from (A) contains at least one compound selected from an aromatic compound, a nitrile compound, a halogen-substituted carbonate compound, a phosphorus-containing compound, a sulfur-containing compound, a silicon-containing compound, and a polymerizable compound. The electrolyte solution for non-aqueous secondary batteries according to any one of claims 1 to 5. (X ¹ ) _n1 -L ¹ -is an atomic group represented by any one of the following formulas (a1) to (a19), for a non-aqueous secondary battery according to any one of claims 1 to 6. Electrolytic solution.

(R ^{301 to} R ³⁰³ are organic groups. R ³⁰⁴ is a halogen-substituted alkyl group. R ³⁰⁵ represents an organic linking group. N2 represents 1 to 5.)   The electrolyte solution for nonaqueous secondary batteries of any one of Claims 1-7 which contains the said nitrogen-containing compound (A) by 0.001-10 mass%.   A nonaqueous secondary battery comprising the positive electrode, the negative electrode, and the electrolyte for a nonaqueous secondary battery according to claim 1.   The nonaqueous secondary battery according to claim 9, wherein a compound having at least one of nickel, cobalt, and manganese is used as an active material of the positive electrode.   The nonaqueous secondary battery according to claim 9 or 10, wherein lithium titanate (LTO) or (composite) carbon material is used as an active material of the negative electrode. A secondary battery electrolyte containing an overcharge inhibitor that does not act below the normal charge positive electrode potential of the battery, is oxidized during overcharge, and increases the resistance of the battery, wherein the overcharge inhibitor is represented by formula (A1). The electrolyte solution for non-aqueous secondary batteries which consists of at least 1 type of compound represented by either of (A6)-(A6).

[In (A1), X ¹ represents an electron-withdrawing group. L ¹¹ represents a linking group. L ¹² has at least one selected from —C (═O) — bond, carbon-carbon multiple bond, nitrogen-nitrogen single bond or multiple bond, and carbon-nitrogen multiple bond, and forms a ring Cy together with a nitrogen atom. Represents a group. L ^{12 is> N-L 11 - (X} 1) may further comprise _n1 group. n1 represents an integer of 1 to 3. ]
[In (A2), R ²¹ represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an aralkyl group, an alkenyl group, or a nitrogen-containing group. L ¹² has the same meaning as ^{L 12} in (A1). L ¹² may further include a> N—C (═O) —R ²¹ group. ]
[In (A3), L ³¹ represents —S (═O) — or —S (═O) ₂ —. R ³¹ and R ³² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an alkoxycarbonyl group, or —L ³¹ —R ³³ . R ³¹ and R ³² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ³³ represents an alkyl group, an aryl group, an aralkyl group, or a nitrogen-containing group. However, at least one of R ³¹ and R ³² is an aryl group or a heteroaryl group, or R ³¹ and R ³² are bonded or condensed to form a ring structure Cy together with a nitrogen atom. ]
[In (A4), R ⁴¹ and R ⁴² each represent an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an acyl group, an alkoxycarbonyl group, or a phosphorus-containing group. R ⁴¹ and R ⁴² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ⁴³ and R ⁴⁴ each represents an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, an aralkyloxy group, a halogen atom, or a nitrogen-containing group. However, at least one of R ⁴¹ and R ⁴² is an aryl group, or R ⁴¹ and R ⁴² are bonded or condensed to form a ring structure with a nitrogen atom. ]
[In (A5), R ⁵¹ and R ⁵² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, or an acyl group. R ⁵¹ and R ⁵² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ^{53 to} R ⁵⁵ each represent a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a nitrogen-containing group. However, at least one of R ⁵¹ and R ⁵² is an aryl group, or R ⁵¹ and R ⁵² are bonded or condensed to form a ring structure together with a nitrogen atom. ]
[In (A6), R ⁶¹ and R ⁶² each represents an alkyl group, an aryl group, a heteroaryl group, an aralkyl group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, or an acyl group. R ⁶¹ and R ⁶² may be bonded or condensed to form a cyclic structure Cy together with the nitrogen atom. Cy is synonymous with Cy in (A1). R ⁶³ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. n6 represents 2-4. ]
[The nitrogen-containing compound (A) may be a multimer linked at any position of (A1) to (A6). ] The electrolyte solution for a non-aqueous secondary battery according to claim 12, wherein the normal charge positive electrode potential of the battery is 4.25 V (Li / Li ⁺ reference) or more. The electrolytic solution for a non-aqueous secondary battery according to claim 12 or 13, wherein the rate of increase in resistance of the following formula calculated by impedance measurement is 5 or more.
Resistance increase rate = (resistance after charging to positive electrode potential 5V)
/ (Resistance after charging to positive electrode potential 4.1V) A nonaqueous secondary battery comprising the positive electrode, the negative electrode, and the electrolyte solution for a nonaqueous secondary battery according to any one of claims 12 to 14,
The positive electrode is a non-aqueous secondary battery that has a material exhibiting an electrode potential (Li / Li ⁺ reference) of 4.25 V or more as an active material, and the resistance of the battery increases during overcharge. The non-aqueous secondary battery according to claim 15, wherein the rate of increase in resistance calculated by impedance measurement is 5 or more.
Resistance increase rate = (resistance after charging to positive electrode potential 5V)
/ (Resistance after charging to positive electrode potential 4.1V) An additive for an electrolyte of a non-aqueous secondary battery represented by the formula (AA), wherein the oxidation start potential of (AA) is a hydrogen atom instead of the substituent Z of (AA) (BB) An additive for an electrolytic solution that is higher than the oxidation initiation potential.

(In the formula, Z, R ¹⁰¹ and R ¹⁰² are organic groups.)   The additive for electrolytic solution according to claim 17, wherein Z is a functional group which is eliminated by oxidation of (AA).   The additive for electrolytic solution according to claim 17 or 18, wherein the additive (AA) is a nitrogen-containing compound (A) represented by any one of the formulas (A1) to (A6).

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