JPH10275632A - Organic electrolyte secondary battery - Google Patents
Organic electrolyte secondary batteryInfo
- Publication number
- JPH10275632A JPH10275632A JP9094798A JP9479897A JPH10275632A JP H10275632 A JPH10275632 A JP H10275632A JP 9094798 A JP9094798 A JP 9094798A JP 9479897 A JP9479897 A JP 9479897A JP H10275632 A JPH10275632 A JP H10275632A
- Authority
- JP
- Japan
- Prior art keywords
- organic electrolyte
- battery
- aromatic compound
- secondary battery
- negative electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、有機電解液二次電
池に関し、さらに詳しくは、安全性が優れた有機電解液
二次電池に関する。The present invention relates to an organic electrolyte secondary battery, and more particularly, to an organic electrolyte secondary battery having excellent safety.
【０００２】[0002]
【従来の技術】有機電解液二次電池は電解液の溶媒とし
て有機溶媒を用いた二次電池であり、この有機電解液二
次電池は、容量が大きく、かつ高電圧、高エネルギー密
度、高出力であることから、ますます需要が増える傾向
にある。2. Description of the Related Art An organic electrolyte secondary battery is a secondary battery using an organic solvent as a solvent of the electrolyte. The organic electrolyte secondary battery has a large capacity, a high voltage, a high energy density, and a high capacity. Because of the output, the demand tends to increase more and more.
【０００３】そして、この電池の有機電解液（以下、電
池を表すとき以外は、単に「電解液」という）の溶媒と
しては、これまで、エチレンカーボネートなどの環状エ
ステルとジメチルカーボネート、ジエチルカーボネー
ト、プロピオン酸メチルなどの鎖状エステルとが混合し
て用いられてきた。[0003] As a solvent for an organic electrolytic solution of this battery (hereinafter simply referred to as "electrolyte solution" except when the battery is referred to), cyclic esters such as ethylene carbonate and dimethyl carbonate, diethyl carbonate, propionate have been used. It has been used in combination with a chain ester such as methyl acid.
【０００４】しかし、この有機電解液二次電池について
さらなる安全性の向上を目指して検討を進めるうちに、
電解液の溶媒として鎖状のエステルを主溶媒として用い
た場合や、負極の充放電可能な容量が多い場合には、電
池の構造に関して充分な工夫をしないと、電池が内部短
絡した場合や釘刺しされた場合の安全性が低下する傾向
のあることがわかった。However, as this organic electrolyte secondary battery has been studied for the purpose of further improving its safety,
If a chain ester is used as the main solvent as the solvent for the electrolyte, or if the negative electrode has a large chargeable / dischargeable capacity, the internal structure of the battery may cause an internal short circuit or It was found that the safety in the case of stabbing tended to decrease.
【０００５】通常は、保護回路などで過充電を防止して
内部短絡を引き起こさないように対策されているし、通
常の内部短絡では電池が発熱するだけで異常な事態には
いたらない。また、釘刺しは滅多に起こるものではな
く、使用者がわざとやらない限り起こりにくい。起こり
得ることとしては、衝撃事故などで電池が部分的に潰さ
れることが想定される。[0005] Usually, measures are taken to prevent overcharging by a protection circuit or the like so as not to cause an internal short circuit, and a normal internal short circuit does not cause an abnormal situation because the battery only generates heat. In addition, nail penetration rarely occurs and is unlikely to occur unless the user intentionally performs it. As a possibility, it is assumed that the battery is partially crushed due to an impact accident or the like.
【０００６】そのために、電池の圧壊試験を行っている
が、通常は安全である。しかし、数十個試験しただけで
は充分に安全であるとはいいがたく、より危険度の高い
条件下で試験を行って安全性を確認することが望まし
い。For this purpose, a crush test of the battery is performed, but it is usually safe. However, it is difficult to say that it is safe enough to test only a few dozen, but it is desirable to confirm the safety by conducting a test under more dangerous conditions.
【０００７】一方、釘刺し試験は、電池の圧壊試験に比
べて少ない部分で電池を確実に短絡させるので、短絡部
位に電流が集中して、より発熱しやすく、電池が部分的
に急速に高温になりやすい。そのため、セパレータのフ
ューズ（溶融による目づまり）のばらつきが生じやす
く、また短絡部位での電解液と負極の反応による発熱が
多くなるなどのため、電池の発熱がさらに多くなる。従
って、安全性の過酷試験として釘刺し試験は有効であ
る。さらに、釘刺し試験を室温で行うよりも４０℃の高
温状態で行う方が、電池がより高温にまで上昇しやす
く、電池の熱暴走反応が起きやすい。また、１／２釘刺
しのように、釘を電池の途中で止める方が、短絡部分が
少なくなり電流がより集中して発熱しやすい。従って、
より高い安全性を得るには、このような加温下での１／
２釘刺し試験にある程度は耐えるものであることが望ま
しい。[0007] On the other hand, in the nail penetration test, the battery is reliably short-circuited in a smaller portion than the battery crush test. Easy to be. For this reason, variations in the fuses (clogging due to melting) of the separator are likely to occur, and the heat generated by the reaction between the electrolyte and the negative electrode at the short-circuited portion increases. Therefore, the nail penetration test is effective as a severe safety test. Further, when the nail penetration test is performed at a high temperature of 40 ° C. than at room temperature, the battery easily rises to a higher temperature, and the thermal runaway reaction of the battery is more likely to occur. Further, when the nail is stopped in the middle of the battery as in the case of a 釘 nail penetration, the short-circuit portion is reduced, and the current is more concentrated and heat is easily generated. Therefore,
To obtain higher safety, 1/1
(2) It is desirable to be able to withstand the nail penetration test to some extent.
【０００８】[0008]
【発明が解決しようとする課題】ところで、カーボンな
どのリチウムを脱挿入できる化合物を負極に用いた場
合、金属リチウムを用いる場合よりも高温での電解液と
の反応性がはるかに低下し、電池の安全性が改善され
る。そして、その安全性改善のためには、リチウムを脱
挿入できる化合物を用いた負極の表面に電解液と反応し
て形成された良質の皮膜の存在が不可欠である。By the way, when a compound such as carbon capable of deintercalating lithium is used for the negative electrode, the reactivity with the electrolytic solution at a higher temperature is much lower than when metal lithium is used. Safety is improved. In order to improve the safety, it is indispensable to have a good quality film formed by reacting with the electrolytic solution on the surface of the negative electrode using a compound capable of deintercalating lithium.
【０００９】負極の表面での電解液との反応について
は、Ｄ．Ａｕｒｂａｃｈらが、カーボン上に有機炭酸塩
（ＲＯＣＯ2 Ｌｉ）、Ｌｉ2 ＣＯ3 や、アルコキシド
（ＲＯＬｉ）などが生成していることを報告している
〔Ｊ．Ｅｌｅｃｔｒｏｃｈｅｍｉｃａｌ Ｓｏｃ．，Ｖ
ｏｌ１４２（Ｎｏ．９），ｐ２８８２（１９９５）〕。
また、同報文では、環状エステルのエチレンカーボネー
トと鎖状エステルのジエチルカーボネートとの混合溶媒
において、環状エステルのエチレンカーボネートに対す
る鎖状エステルのジエチルカーボネートの割合が１：１
より多くなると、サイクル特性に悪影響があると報告さ
れている。さらに、本発明者らの検討においても、特に
ジエチルカーボネートのような鎖状エステルの割合が多
くなると、とりわけメチル基を有する鎖状エステルの割
合が多くなると、短絡や釘刺しにおける安全性が低下す
る傾向のあることがわかってきた。Regarding the reaction with the electrolyte on the surface of the negative electrode, see D. Aurbach et al. Report that organic carbonates (ROCO 2 Li), Li 2 CO 3 , alkoxides (ROLi) and the like are formed on carbon [J. Electrochemical Soc. , V
ol142 (No. 9), p2882 (1995)].
In the same report, in a mixed solvent of cyclic ester ethylene carbonate and chain ester diethyl carbonate, the ratio of chain ester diethyl carbonate to cyclic ester ethylene carbonate is 1: 1.
It is reported that higher levels have an adverse effect on cycling characteristics. Furthermore, in the study of the present inventors, particularly, when the ratio of a chain ester such as diethyl carbonate is increased, especially when the ratio of a chain ester having a methyl group is increased, safety in short-circuiting and nail penetration decreases. I have found a tendency.
【００１０】従って、本発明は、従来の有機電解液二次
電池の安全性に関する問題点を解決し、安全性の優れた
有機電解液二次電池を提供することを目的とする。Accordingly, an object of the present invention is to solve the problems related to the safety of the conventional organic electrolyte secondary battery and to provide an organic electrolyte secondary battery having excellent safety.
【００１１】[0011]
【課題を解決するための手段】本発明は、正極、一部が
電解液と反応して表面に皮膜が形成された負極および鎖
状エステルを主溶媒とする電解液を有する有機電解液二
次電池において、上記電解液にアルキル基を有する非イ
オン性芳香族化合物を含有させることによって、上記課
題を解決したものである。SUMMARY OF THE INVENTION The present invention relates to a secondary organic electrolyte comprising a positive electrode, a negative electrode having a film formed on its surface by partially reacting with an electrolyte, and an electrolyte having a chain ester as a main solvent. In a battery, the above problem has been solved by including a nonionic aromatic compound having an alkyl group in the electrolytic solution.
【００１２】[0012]
【発明の実施の形態】本発明において用いるアルキル基
を有する非イオン性芳香族化合物としては、たとえば、
トリメリット酸エステル、トリ−２−エチルヘキシルト
リメリテート〔（Ｃ6 Ｈ3 （ＣＯＯＣ8 Ｈ17）3 〕など
のトリメリット酸エステルの誘導体、ジメチルフタレー
タ〔（Ｃ6 Ｈ4 （ＣＯＯＣＨ3 ）2 〕、ジブチルフタレ
ート〔（Ｃ6 Ｈ4 （ＣＯＯＣ4 Ｈ9 ）2 〕、ブチルベン
ゼン（Ｃ6 Ｈ5 −Ｃ4 Ｈ9 、ノルマルまたはターシャリ
ーまたはイソ）、シクロヘキシルベンゼン（Ｃ6 Ｈ11−
Ｃ6 Ｈ5 ）、トルエンなどが挙げられる。BEST MODE FOR CARRYING OUT THE INVENTION The nonionic aromatic compound having an alkyl group used in the present invention includes, for example,
Trimellitic acid esters, derivatives of trimellitic acid esters, such as tri-2-ethylhexyl trimellitate [(C 6 H 3 (COOC 8 H 17) 3 ], dimethyl phthalate regulator [(C 6 H 4 (COOCH 3 ) 2 ], dibutyl phthalate [(C 6 H 4 (COOC 4 H 9) 2 ], butylbenzene (C 6 H 5 -C 4 H 9, n or tertiary or iso), cyclohexylbenzene (C 6 H 11 -
C 6 H 5 ), toluene and the like.
【００１３】上記非イオン性芳香族化合物のアルキル基
は、炭素数が２個以上であることが望ましく、より望ま
しくは炭素数が４個以上、さらに望ましくは炭素数が５
個以上である。また、上記アルキル基は、ベンゼン環に
直接結合していても良いが、ＣＯＯ基を介してベンゼン
環に結合しているのがさらに望ましい。つまり、アルキ
ル基は長い方がまたＣＯＯ基のある方が負極表面でのバ
リアー効果（高温で電極と電解液との急速な反応を抑え
る効果）が大きいからである。ここで、上記非イオン性
芳香族化合物における非イオン性とは、カチオン部やア
ニオン部を分子内に持たないことをいう。The alkyl group of the nonionic aromatic compound preferably has 2 or more carbon atoms, more preferably has 4 or more carbon atoms, and still more preferably has 5 or more carbon atoms.
Number or more. The alkyl group may be directly bonded to the benzene ring, but is more preferably bonded to the benzene ring via a COO group. That is, the longer the alkyl group and the presence of the COO group, the greater the barrier effect on the negative electrode surface (the effect of suppressing a rapid reaction between the electrode and the electrolyte at a high temperature). Here, non-ionic in the non-ionic aromatic compound means that the compound does not have a cation part or an anion part in a molecule.
【００１４】本発明において、上記アルキル基を有する
非イオン性芳香族化合物の電解液中での含有量は、電解
液溶媒１００容量部に対して０．１容量部以上であるこ
とが望ましく、０．２容量部以上であることがさらに望
ましく、０．５容量部以上がもっとも望ましい。なお、
上記アルキル基を有する非イオン性芳香族化合物が固体
の場合は、その密度で体積換算した値を用いる。また、
上記アルキル基を有する非イオン性芳香族化合物の電解
液中での含有量は、電解液溶媒１００容量部に対して１
０容量部以下が望ましく、２容量部以下がさらに望まし
く、１容量部以下がもっとも望ましい。In the present invention, the content of the nonionic aromatic compound having an alkyl group in the electrolytic solution is preferably 0.1 part by volume or more based on 100 parts by volume of the electrolytic solution solvent. More preferably, it is at least 2 parts by volume, most preferably at least 0.5 parts by volume. In addition,
When the nonionic aromatic compound having an alkyl group is a solid, a value obtained by converting the density into a volume is used. Also,
The content of the nonionic aromatic compound having an alkyl group in the electrolytic solution is 1 to 100 parts by volume of the electrolytic solution solvent.
It is preferable that the capacity is 0 capacity or less, more preferably 2 capacity or less, and most preferably 1 capacity or less.
【００１５】上記アルキル基を有する非イオン性芳香族
化合物の電解液中での含有量が上記より少ない場合は安
全性を充分に向上させることができず、また、上記アル
キル基を有する非イオン性芳香族化合物の電解液中での
含有量が上記より多い場合は電池のサイクル特性や負荷
特性が悪くなるおそれがある。When the content of the above-mentioned nonionic aromatic compound having an alkyl group in the electrolytic solution is lower than the above, the safety cannot be sufficiently improved, and the nonionic aromatic compound having the above alkyl group cannot be improved. If the content of the aromatic compound in the electrolytic solution is higher than the above, the cycle characteristics and load characteristics of the battery may be deteriorated.
【００１６】このような非イオン性芳香族化合物はプロ
ピレンカーボネートのような環状エステルと混合して用
いられたことはあるが、鎖状エステルを主溶媒とする系
で用いられた例は、いまだ見いだしていない。Although such a nonionic aromatic compound has been used as a mixture with a cyclic ester such as propylene carbonate, an example in which it is used in a system using a chain ester as a main solvent has not yet been found. Not.
【００１７】芳香族化合物の代表であるベンゼンをプロ
ピレンカーボネートなどの環状の炭酸エステルを主溶媒
とする電解液に添加して、貯蔵性を改善することは既に
報告されている〔Ｍ．Ｍｏｒｉｔａ ， Ｓ．Ａｏｋｉ
ａｎｄ Ｙ．Ｍａｔｓｕｄａ，Ｅｌｅｃｔｒｏｃｈｉ
ｍｉｃａ． Ａｃｔａ．，Ｖｏｌ．３７（Ｎｏ．１），
ｐ１１９−１２３（１９９２）〕。トルエンについても
電解液に混合して用いる例が報告されている（特開平３
−７７２８１号公報）。It has been reported that benzene, which is a representative of aromatic compounds, is added to an electrolyte containing a cyclic carbonate such as propylene carbonate as a main solvent to improve the storage property [M. Morita, S.M. Aoki
and Y. Matsuda, Electrochi
mica. Acta. , Vol. 37 (No. 1),
p119-123 (1992)]. An example has been reported in which toluene is used by mixing it with an electrolytic solution (Japanese Unexamined Patent Publication No.
-77281).
【００１８】本発明者らは、芳香族化合物の電解液への
添加が電池の安全性に及ぼす効果を詳細に検討した。こ
れを詳しく説明すると、本発明者らは、まず、内部短絡
などを想定してリチウムイオン電池の釘刺し試験を行っ
たところ、通常の市販のリチウムイオン電池では危険性
が低いが、電池のエネルギー密度が高くなるにつれて危
険性が増していくことがわかった。The present inventors have studied in detail the effect of adding an aromatic compound to an electrolyte on the safety of a battery. To explain this in detail, the present inventors first performed a nail penetration test of a lithium ion battery assuming an internal short circuit or the like. It was found that the risk increased as the density increased.
【００１９】これらの電池の負極には通常炭素材料など
のリチウムを脱挿入できる化合物が使用されているが、
負極が過充電されて多少リチウムが電着した場合、約１
００℃付近から電解液と電着リチウムやリチウムが挿入
された炭素材料との間に発熱反応が生じる。一方、正極
はリチウムが脱離することによって、電解液との反応開
始温度が低くなり、負極の反応熱によって正極の熱暴走
温度にまで温度が上昇すると、電池は異常発熱を起こす
ことになる。Compounds capable of deintercalating lithium, such as carbon materials, are usually used for the negative electrodes of these batteries.
If the negative electrode is overcharged and some lithium is electrodeposited, about 1
From around 00 ° C., an exothermic reaction occurs between the electrolytic solution and electrodeposited lithium or a carbon material into which lithium is inserted. On the other hand, when the lithium is desorbed from the positive electrode, the temperature at which the reaction with the electrolyte solution starts decreases, and when the temperature rises to the thermal runaway temperature of the positive electrode due to the heat of reaction of the negative electrode, the battery generates abnormal heat.
【００２０】このような連続反応を伴う発熱現象がある
ため、通常使用条件での電池の負極の充放電可能な容量
が電池の単位体積あたり８５ｍＡｈ／ｃｍ3 を越えた場
合には、電池が過充電された時の安全性が低下する。つ
まり、負極の単位体積あたりの放電可能な容量が多いほ
ど、過充電時に発熱した場合に電池単位体積あたりの発
熱量が多くなり、電池温度が正極の熱暴走温度にまで上
昇する可能性が高くなるのである。従って、単位体積あ
たりの負極容量の大きい電池ほど、負極と電解液との発
熱反応を抑制する必要がある。また、電池サイズが大き
い場合も発熱量が多くなるので、負極と電解液との発熱
反応を抑制する必要があり、本発明のアルキル基を有す
る非イオン性芳香族化合物を含有させる効果が顕著に発
現する。単電池のサイズが１０ｃｍ3 以上、特に１５ｃ
ｍ3 以上になると本発明の効果がより顕著に発現する。Due to such a heat generation phenomenon accompanied by a continuous reaction, when the chargeable / dischargeable capacity of the negative electrode of the battery under normal use conditions exceeds 85 mAh / cm 3 per unit volume of the battery, the battery becomes excessive. Safety when charged is reduced. In other words, the greater the dischargeable capacity per unit volume of the negative electrode, the greater the amount of heat generated per unit volume of the battery if heat is generated during overcharge, and the higher the possibility that the battery temperature will rise to the thermal runaway temperature of the positive electrode. It becomes. Therefore, it is necessary to suppress the exothermic reaction between the negative electrode and the electrolytic solution as the battery has a larger negative electrode capacity per unit volume. Further, since the calorific value also increases when the battery size is large, it is necessary to suppress the exothermic reaction between the negative electrode and the electrolyte, and the effect of containing the nonionic aromatic compound having an alkyl group of the present invention is remarkable. Express. The size of the cell is 10cm 3 or more, especially 15c
When it is at least m 3, the effects of the present invention will be more remarkably exhibited.
【００２１】電池の安全性向上のために、電解液に不燃
性溶媒を添加したり、ポリマーを溶解させたり、芳香族
化合物を添加することが知られているが、本発明は、上
記特定の芳香族化合物を鎖状エステルを主溶媒とする電
池に用いることにより、安全性の向上に特に優れた効果
を見出したものである。本発明において、上記特定の芳
香族化合物の添加により安全性を改善できる理由は以下
のように考えられる。It is known to add a nonflammable solvent, dissolve a polymer, or add an aromatic compound to the electrolytic solution in order to improve the safety of the battery. It has been found that the use of an aromatic compound in a battery containing a chain ester as a main solvent has a particularly excellent effect in improving safety. In the present invention, the reason why the safety can be improved by adding the above specific aromatic compound is considered as follows.
【００２２】カーボン材料のようにリチウムを脱挿入で
きる化合物によって負極を作製することにより、電解液
と負極との高温での反応性はリチウムを用いた場合より
も抑制されているが、負極の充放電可能な容量が増える
ことによって電解液との反応性が増加し、電池が発熱し
て負極と電解液との反応が起こったときの発熱量が多く
なり、温度が上昇しやすくなる。しかし、芳香族化合物
が電解液に添加されていると、該芳香族化合物が負極の
表面に吸着し、負極の表面と鎖状エステルとの直接の接
触を抑制するので、負極と電解液との反応性が低減され
て、温度上昇が制限されるものと考えられる。そして、
芳香族化合物は、アルキル基を有するものの方が効果が
高いこともわかった。その詳細は後記の実施例で明らか
にする。By preparing the negative electrode with a compound capable of deintercalating lithium such as a carbon material, the reactivity between the electrolyte and the negative electrode at a high temperature is suppressed as compared with the case where lithium is used. As the dischargeable capacity increases, the reactivity with the electrolytic solution increases, the amount of heat generated when the battery generates heat and the reaction between the negative electrode and the electrolytic solution occurs increases, and the temperature easily rises. However, when the aromatic compound is added to the electrolyte, the aromatic compound is adsorbed on the surface of the negative electrode and suppresses the direct contact between the surface of the negative electrode and the chain ester. It is believed that the reactivity is reduced and the temperature rise is limited. And
It was also found that aromatic compounds having an alkyl group were more effective. The details will be clarified in Examples described later.
【００２３】電解液の主溶媒として用いる鎖状エステル
は、たとえば、ジメチルカーボネート、ジエチルカーボ
ネート、メチルエチルカーボネート、プロピオン酸メチ
ルなどの鎖状のＣＯＯ−結合を有する有機溶媒である。
主溶媒というのは、これらの鎖状エステルを含んだ全電
解液溶媒中で鎖状エステルが５０体積％を超えることを
意味する。鎖状エステルが６５体積％を超えると釘刺し
試験での電池の安全性が低下する傾向にあり、アルキル
基を有する非イオン性芳香族化合物の添加効果が大きく
なる。そして、鎖状エステルが７０体積％を超えるとア
ルキル基を有する非イオン性芳香族化合物の添加効果が
より一層大きくなり、鎖状エステルが７５体積％を超え
るとアルキル基を有する非イオン性芳香族化合物の添加
効果がさらに大きくなる。また、鎖状エステルがメチル
基を有する場合も電池の安全性が低下しやすくなるの
で、アルキル基を有する非イオン性芳香族化合物の添加
効果がより一層顕著になる。The chain ester used as the main solvent of the electrolytic solution is, for example, an organic solvent having a chain COO-bond, such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propionate and the like.
The main solvent means that the chain ester exceeds 50% by volume in the total electrolyte solvent containing these chain esters. If the chain ester exceeds 65% by volume, the safety of the battery in the nail penetration test tends to decrease, and the effect of adding the nonionic aromatic compound having an alkyl group increases. When the chain ester exceeds 70% by volume, the effect of adding the nonionic aromatic compound having an alkyl group is further increased, and when the chain ester exceeds 75% by volume, the nonionic aromatic compound having an alkyl group is added. The effect of adding the compound is further increased. Also, when the chain ester has a methyl group, the safety of the battery is apt to be lowered, so that the effect of adding the nonionic aromatic compound having an alkyl group becomes more remarkable.
【００２４】また、上記鎖状エステルに下記の誘電率が
高いエステル（誘電率３０以上）を混合して用いると、
鎖状エステルだけで用いる場合よりも、サイクル特性や
電池の負荷特性が向上するので、電池としてはより望ま
しいものとなる。このような誘電率の高いエステルとし
ては、たとえば、プロピレンカーボネート（ＰＣ）、エ
チレンカーボネート（ＥＣ）、ブチレンカーボネート
（ＢＣ）、ガンマーブチロラクトン（γ−ＢＬ）、エチ
レングリコールサルファイト（ＥＧＳ）などが挙げら
れ、特に環状構造のものが好ましく、とりわけ環状のカ
ーボネートが好ましく、エチレンカーボネート（ＥＣ）
が最も好ましい。When the above-mentioned chain ester is mixed with the following ester having a high dielectric constant (dielectric constant of 30 or more),
Since the cycle characteristics and the load characteristics of the battery are improved as compared with the case where only the chain ester is used, the battery is more desirable. Examples of such an ester having a high dielectric constant include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), gamma-butyrolactone (γ-BL), and ethylene glycol sulfite (EGS). In particular, those having a cyclic structure are preferred, and cyclic carbonates are particularly preferred. Ethylene carbonate (EC)
Is most preferred.
【００２５】上記誘電率の高いエステルは電解液の全溶
媒中の４０体積％未満が好ましく、より好ましくは３０
体積％以下、さらに好ましくは２５体積％以下である。
そして、これらの誘電率の高いエステルによる安全性の
向上は、上記誘電率の高いエステルが電解液の全溶媒中
で１０体積％以上になると顕著になり、２０体積％に達
するとさらに顕著になる。The ester having a high dielectric constant is preferably less than 40% by volume of the total solvent of the electrolytic solution, more preferably 30% by volume.
% By volume or less, more preferably 25% by volume or less.
The improvement of the safety by these esters having a high dielectric constant becomes remarkable when the ester having a high dielectric constant becomes 10% by volume or more in the entire solvent of the electrolytic solution, and becomes further remarkable when the ester reaches 20% by volume. .
【００２６】上記誘電率の高いエステル以外に鎖状エス
テルと併用可能な溶媒としては、たとえば１，２−ジメ
トキシエタン（ＤＭＥ）、１，３−ジオキソラン（Ｄ
Ｏ）、テトラヒドロフラン（ＴＨＦ）、２−メチル−テ
トラヒドロフラン（２Ｍｅ−ＴＨＦ）、ジエチルエーテ
ル（ＤＥＥ）などが挙げられる。そのほか、アミンイミ
ド系有機溶媒や、含イオウまたは含フッ素系有機溶媒な
ども用いることができる。Examples of the solvent which can be used in combination with the chain ester other than the ester having a high dielectric constant include, for example, 1,2-dimethoxyethane (DME), 1,3-dioxolane (D
O), tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (2Me-THF), diethyl ether (DEE) and the like. In addition, an amine imide-based organic solvent, a sulfur-containing or fluorine-containing organic solvent, and the like can also be used.
【００２７】電解液の電解質としては、たとえばＬｉＣ
ｌＯ4 、ＬｉＰＦ6 、ＬｉＢＦ4 、ＬｉＡｓＦ6 、Ｌｉ
ＳｂＦ6 、ＬｉＣＦ3 ＳＯ3 、ＬｉＣ4 Ｆ9 ＳＯ3 、Ｌ
ｉＣＦ3 ＣＯ2 、Ｌｉ2 Ｃ2 Ｆ4 （ＳＯ3 ）2 、ＬｉＮ
（ＣＦ3 ＳＯ2 ）2 、ＬｉＣ（ＣＦ3 ＳＯ2 ）3 、Ｌｉ
Ｃn Ｆ2n+1ＳＯ3 （ｎ≧２）、ＬｉＮ（Ｒｆ3 ＯＳ
Ｏ2 ）2 〔ここでＲｆはフルオロアルキル基〕などが単
独でまたは２種以上混合して用いられるが、特にＬｉＰ
Ｆ6 やＬｉＣ4 Ｆ9 ＳＯ3 などが充放電特性が良好なこ
とから望ましい。電解液中における電解質の濃度は、特
に限定されるものではないが、濃度を１ｍｏｌ／ｌ以上
にすると安全性が向上するので望ましく、１．２ｍｏｌ
／ｌ以上がさらに望ましい。また、電解液中における電
解質の濃度が１．７ｍｏｌ／ｌ以下であると良好な電気
特性が保たれるので望ましく、１．５ｍｏｌ／ｌ以下で
あることがさらに望ましい。As the electrolyte of the electrolytic solution, for example, LiC
10 4 , LiPF 6 , LiBF 4 , LiAsF 6 , Li
SbF 6 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , L
iCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN
(CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , Li
C n F 2n + 1 SO 3 (n ≧ 2), LiN (Rf 3 OS
O 2 ) 2 [Rf is a fluoroalkyl group] or the like may be used alone or in combination of two or more.
F 6 and LiC 4 F 9 SO 3 are desirable because of their good charge / discharge characteristics. The concentration of the electrolyte in the electrolytic solution is not particularly limited, but it is desirable that the concentration be 1 mol / l or more, since safety is improved.
/ L or more is more desirable. Further, when the concentration of the electrolyte in the electrolytic solution is 1.7 mol / l or less, good electric characteristics are maintained, and it is more preferable that the concentration is 1.5 mol / l or less.
【００２８】正極活物質としては、たとえばＬｉＣｏＯ
2 などのリチウムコバルト酸化物、ＬｉＭｎ2 Ｏ4 など
のリチウムマンガン酸化物、ＬｉＮｉＯ2 などのリチウ
ムニッケル酸化物、二酸化マンガン、五酸化バナジウ
ム、クロム酸化物、などの金属酸化物または二硫化チタ
ン、二硫化モリブデンなどの金属硫化物が用いられ、そ
れらの正極活物質に導電助剤やポリフッ化ビニリデンな
どの結着剤などを適宜添加した合剤を、アルミニウム箔
などの集電材料を芯材として成形体に仕上げたものが用
いられる。As the positive electrode active material, for example, LiCoO
Lithium cobalt oxides such as 2, lithium manganese oxide such as LiMn 2 O 4, lithium nickel oxides such as LiNiO 2, manganese dioxide, vanadium pentoxide, chromium oxide, a metal oxide or titanium disulfide, such as a two Metal sulfides such as molybdenum sulfide are used, and a mixture in which a conductive auxiliary agent or a binder such as polyvinylidene fluoride is appropriately added to the positive electrode active material is formed using a current collector material such as an aluminum foil as a core material. Finished body is used.
【００２９】そして、正極は、たとえばそれらの正極活
物質に導電助剤やポリフッ化ビニリデンなどの結着剤な
どを適宜添加した合剤を、アルミニウム箔などの集電材
料を芯材として成形体に仕上げたものが用いられる。For the positive electrode, for example, a mixture obtained by appropriately adding a conductive additive or a binder such as polyvinylidene fluoride to the positive electrode active material is formed into a molded body using a current collector material such as aluminum foil as a core material. Finished products are used.
【００３０】特にＬｉＮｉＯ2 、ＬｉＣｏＯ2 、ＬｉＭ
ｎ2 Ｏ4 などの充電時の開路電圧がＬｉ基準で４Ｖ以上
を示すリチウム複合酸化物を正極活物質として用いる場
合には、高エネルギー密度が得られるので望ましい。特
に充電したＬｉＣｏＯ2 やＬｉＮｉＯ2 は、電解液との
反応開始温度がＬｉＭｎ2 Ｏ4 より低く、負極の発熱に
よって正極の熱暴走温度に達しやすいので、本発明の効
果がより顕著に発揮される。In particular, LiNiO 2 , LiCoO 2 , LiM
It is desirable to use a lithium composite oxide such as n 2 O 4 having an open circuit voltage of 4 V or more on the Li basis as a positive electrode active material, since a high energy density can be obtained. In particular, the charged LiCoO 2 or LiNiO 2 has a lower reaction initiation temperature with the electrolytic solution than LiMn 2 O 4 and easily reaches the thermal runaway temperature of the positive electrode due to heat generation of the negative electrode, so that the effect of the present invention is more remarkably exhibited. .
【００３１】負極に用いる材料としては、リチウムイオ
ンをドープ、脱ドープできるものであればよく、たとえ
ば、黒鉛、熱分解炭素類、コークス類、ガラス状炭素
類、有機高分子化合物の焼成体、メソカーボンマイクロ
ビーズ、炭素繊維、活性炭などの炭素化合物あるいはＳ
ｉ、Ｓｎ、Ｉｎなどとリチウムとの合金あるいはＬｉに
近い低電位で充放電できるＳｉ、Ｓｎ、Ｉｎなどの酸化
物などを用いることができる。The material used for the negative electrode may be any material capable of doping and undoping lithium ions. Examples of the material include graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, meso materials. Carbon compounds such as carbon microbeads, carbon fiber, activated carbon or S
An alloy of lithium with i, Sn, In, or the like, or an oxide of Si, Sn, In, or the like that can be charged and discharged at a low potential close to Li can be used.
【００３２】負極に炭素材料を用いる場合、該炭素材料
は下記の特性を持つものが望ましい。すなわち、その
（００２）面の層間距離ｄ002 に関しては、３．５Å以
下が望ましく、より望ましくは３．４５Å以下、さらに
望ましくは３．４Å以下である。また、ｃ軸方向の結晶
子の大きさＬｃは、３０Å以上が望ましく、より望まし
くは８０Å以上、さらに望ましくは２５０Å以上であ
る。そして、その平均粒径は８〜１５μｍ、特に１０〜
１３μｍが望ましく、純度は９９．９％以上が望まし
く。When a carbon material is used for the negative electrode, the carbon material desirably has the following characteristics. That is, the interlayer distance d 002 of the (002) plane is desirably 3.5 ° or less, more desirably 3.45 ° or less, and further desirably 3.4 ° or less. The crystallite size Lc in the c-axis direction is desirably 30 ° or more, more desirably 80 ° or more, and further desirably 250 ° or more. And the average particle size is 8 to 15 μm, especially 10 to 10 μm.
13 μm is desirable, and the purity is desirably 99.9% or more.
【００３３】[0033]
【実施例】つぎに、実施例をあげて本発明をより具体的
に説明する。ただし、本発明はそれらの実施例のみに限
定されるものではない。Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.
【００３４】実施例１ メチルエチルカーボネートとエチレンカーボネートとを
体積比７６：２４で混合し、この混合溶媒１００容量部
に対してトリ−２−エチルヘキシルトリメリテート
〔（Ｃ6 Ｈ3 （ＣＯＯＣ8 Ｈ17）3 、以下、「ＴＯＴ
Ｍ」と略す）を１容量部添加して混合し、ＬｉＰＦ6 を
１．４ｍｏｌ／ｌ溶解させて、組成が１．４ｍｏｌ／ｌ
ＬｉＰＦ6 ／ＥＣ：ＭＥＣ（２４：７６体積比）＋１
％ＴＯＴＭで示される電解液を調製した。Example 1 Methyl ethyl carbonate and ethylene carbonate were mixed in a volume ratio of 76:24, and tri-2-ethylhexyl trimellitate [(C 6 H 3 (COOC 8 H) was added to 100 parts by volume of the mixed solvent. 17 ) 3 ;
M ") was added and mixed, and LiPF 6 was dissolved at 1.4 mol / l to give a composition of 1.4 mol / l.
LiPF 6 / EC: MEC (24:76 volume ratio) +1
An electrolytic solution represented by% TOTM was prepared.
【００３５】上記電解液におけるＥＣはエチレンカーボ
ネートの略称であり、ＭＥＣはメチルエチルカーボネー
トの略称である。従って、上記電解液を示す１．４ｍｏ
ｌ／ｌ ＬｉＰＦ6 ／ＥＣ：ＭＥＣ（２４：７６体積
比）＋１％ＴＯＴＭは、メチルエチルカーボネート７６
体積％とエチレンカーボネート２４体積％との混合溶媒
にＬｉＰＦ6 を１．４ｍｏｌ／ｌ溶解させ、かつ上記混
合溶媒１００容量部に対してＴＯＴＭを１容量部溶解さ
せたものであることを示している。EC in the above electrolyte is an abbreviation for ethylene carbonate, and MEC is an abbreviation for methyl ethyl carbonate. Therefore, the above-mentioned electrolyte solution of 1.4mo
1 / l LiPF 6 / EC: MEC (24:76 volume ratio) + 1% TOTM is methyl ethyl carbonate 76
It shows that 1.4 mol / l of LiPF 6 was dissolved in a mixed solvent of 20% by volume of ethylene carbonate and 24% by volume of ethylene carbonate, and 1 part by volume of TOTM was dissolved in 100 parts by volume of the mixed solvent. .
【００３６】これとは別に、正極活物質としてのＬｉＣ
ｏＯ2 に導電助剤としてリン状黒鉛を重量比１００：７
で加えて混合し、この混合物と、ポリフッ化ビニリデン
をＮ−メチルピロリドンに溶解させた溶液とを混合して
スラリーにした。この正極合剤スラリーを７０メッシュ
の網を通過させて大きなものを取り除いた後、厚さ２０
μｍのアルミニウム箔からなる正極集電体の両面に均一
に塗付して乾燥し、その後、ローラプレス機により圧縮
成形し、切断した後、リード体を溶接して、帯状の正極
を作製した。Separately, LiC as a positive electrode active material
Phosphorous graphite is added to oO 2 as a conductive additive in a weight ratio of 100: 7.
The mixture was mixed with a solution prepared by dissolving polyvinylidene fluoride in N-methylpyrrolidone to form a slurry. After passing the positive electrode mixture slurry through a 70-mesh net to remove a large one,
The positive electrode current collector made of a μm aluminum foil was uniformly applied to both sides and dried, then compression-molded by a roller press, cut, and then welded to a lead body to produce a belt-shaped positive electrode.
【００３７】つぎに、黒鉛系炭素材料（ただし、層間距
離ｄ002 ＝３．３７Å、ｃ軸方向の結晶子サイズＬｃ＝
９５０Å、平均粒径１０μｍ、純度９９．９％という特
性を持つ黒鉛系炭素材料）９０重量部を、フッ化ビニリ
デン１０重量部をＮ−メチルピロリドンに溶解させた溶
液と混合してスラリーにした。この負極合剤スラリーを
７０メッシュの網を通過させて大きなものを取り除いた
後、厚さ１０μｍの帯状の銅箔からなる負極集電体の両
面に均一に塗付して乾燥し、その後、ローラプレス機に
より圧縮成形し、切断した後、リード体を溶接して、帯
状の負極を作製した。Next, a graphite-based carbon material (interlayer distance d 002 = 3.37 °, crystallite size Lc in the c-axis direction =
90 parts by weight of a graphite-based carbon material having characteristics of 950 °, an average particle diameter of 10 μm, and a purity of 99.9%) were mixed with a solution of 10 parts by weight of vinylidene fluoride in N-methylpyrrolidone to form a slurry. The negative electrode mixture slurry was passed through a 70-mesh net to remove large particles, and then uniformly applied to both surfaces of a negative electrode current collector made of a strip-shaped copper foil having a thickness of 10 μm, dried, and then rolled. After compression molding with a press machine and cutting, the lead body was welded to produce a strip-shaped negative electrode.
【００３８】前記帯状正極を厚さ２５μｍの微孔性ポリ
エチレンフィルムを介して上記帯状負極に重ね、渦巻状
に巻回して渦巻状電極体とした後、外径１８ｍｍの有底
円筒状の電池ケース内に充填し、正極および負極のリー
ド体の溶接を行った。ここで、正極と負極との互いに対
向した部分の単位体積あたりの活物質含有合剤の正極／
負極重量比は２．０６であった。負極の充放電容量は、
この電池の通常充電条件（１４００ｍＡで充電し、４．
１Ｖに達した後は４．１Ｖの定電圧で充電する操作を２
時間３０分行う）では、８５ｍＡｈ／ｃｍ3 であった。The above-mentioned band-shaped positive electrode is superposed on the above-mentioned band-shaped negative electrode via a microporous polyethylene film having a thickness of 25 μm, spirally wound into a spiral electrode body, and then a cylindrical battery case with a bottom having an outer diameter of 18 mm. And the lead bodies of the positive electrode and the negative electrode were welded. Here, the positive electrode of the active material-containing mixture per unit volume of the opposed parts of the positive electrode and the negative electrode /
The negative electrode weight ratio was 2.06. The charge and discharge capacity of the negative electrode is
The battery was charged under normal charging conditions (charged at 1400 mA;
After reaching 1 V, the charging operation at a constant voltage of 4.1 V
(Performed for 30 minutes), the value was 85 mAh / cm 3 .
【００３９】つぎに電解液を電池ケース内に注入し、電
解液がセパレータなどに充分に浸透した後、封口し、予
備充電、エイジングを行い、図１に示す構造の筒形の有
機電解液二次電池を作製した。Next, the electrolytic solution was poured into the battery case, and after the electrolytic solution sufficiently permeated into the separator and the like, sealing was performed, preliminary charging and aging were performed, and a cylindrical organic electrolytic solution having a structure shown in FIG. A secondary battery was manufactured.
【００４０】図１に示す電池について概略的に説明する
と、１は前記の正極で、２は前記の負極である。ただ
し、図１では、繁雑化を避けるため、正極１や負極２の
作製にあたって使用された集電体などは図示しておら
ず、これらの正極１と負極２はセパレータ３を介して渦
巻状に巻回され、渦巻状電極体として、電解液と共に、
ステンレス鋼製の電池ケース４内に収容されている。The battery shown in FIG. 1 will be described briefly. 1 is the positive electrode and 2 is the negative electrode. However, FIG. 1 does not show the current collectors used for producing the positive electrode 1 and the negative electrode 2 in order to avoid complication, and the positive electrode 1 and the negative electrode 2 are spirally interposed through the separator 3. Wound, as a spiral electrode body, together with the electrolyte,
It is housed in a battery case 4 made of stainless steel.
【００４１】上記電解液には前記のようにＴＯＴＭ（す
なわち、トリ−２−エチルヘキシルトリメリテート）を
含有させており、上記電池ケース４は負極端子を兼ねて
いて、その底部には絶縁体５が配置され、渦巻状電極体
上にも絶縁体６が配置されている。そして、電池ケース
４の開口部には環状の絶縁パッキング７を介して封口体
８が配置され、電池ケース４の開口端部の内方への締め
付けにより電池内部を密閉構造にしている。ただし、上
記封口体８には、電池内部に発生したガスをある一定圧
力まで上昇した段階で電池外部に排出して、電池の高圧
下での破裂を防止するための可逆式のベント機構が組み
込まれている。As described above, the electrolyte contains TOTM (that is, tri-2-ethylhexyl trimellitate), and the battery case 4 also serves as a negative electrode terminal, and an insulator 5 Are arranged, and the insulator 6 is also arranged on the spiral electrode body. A sealing body 8 is arranged at the opening of the battery case 4 via an annular insulating packing 7, and the inside of the battery is sealed by tightening the opening end of the battery case 4 inward. However, a reversible vent mechanism for preventing the gas generated inside the battery from being ruptured under a high pressure by discharging the gas generated inside the battery to a certain pressure when the gas is raised to a certain pressure and preventing the battery from being ruptured under a high pressure. Have been.
【００４２】実施例２ ＴＯＴＭに代えてジブチルフタレート〔Ｃ6 Ｈ4 （ＣＯ
ＯＣ4 Ｈ9 ）2 〕を用いた以外は、実施例１と同様にし
て筒形の有機電解液二次電池を作製した。Example 2 Instead of TOTM, dibutyl phthalate [C 6 H 4 (CO
A cylindrical organic electrolyte secondary battery was fabricated in the same manner as in Example 1 except that OC 4 H 9 ) 2 ] was used.
【００４３】実施例３ ＴＯＴＭに代えてジメチルフタレート〔Ｃ6 Ｈ4 （ＣＯ
ＯＣＨ3 ）2 〕を用いた以外は、実施例１と同様にして
筒形の有機電解液二次電池を作製した。Example 3 Instead of TOTM, dimethyl phthalate [C 6 H 4 (CO
A cylindrical organic electrolyte secondary battery was manufactured in the same manner as in Example 1 except that OCH 3 ) 2 ] was used.
【００４４】実施例４ ＴＯＴＭに代えてトルエンを用いた以外は、実施例１と
同様にして筒形の有機電解液二次電池を作製した。Example 4 A cylindrical organic electrolyte secondary battery was produced in the same manner as in Example 1 except that toluene was used instead of TOTM.
【００４５】比較例１ 電解液にアルキル基を有する非イオン性芳香族化合物を
含有させなかった以外は、実施例１と同様にして筒形の
有機電解液二次電池を作製した。Comparative Example 1 A cylindrical organic electrolyte secondary battery was produced in the same manner as in Example 1 except that the electrolyte did not contain a nonionic aromatic compound having an alkyl group.
【００４６】比較例２ エチレンカーボネート（ＥＣ）とメチルエチルカーボネ
ート（ＭＥＣ）との比率を体積比で１：２にした以外
は、比較例１と同様にして筒形の有機電解液二次電池を
作製した。Comparative Example 2 A cylindrical organic electrolyte secondary battery was prepared in the same manner as in Comparative Example 1 except that the volume ratio of ethylene carbonate (EC) to methyl ethyl carbonate (MEC) was 1: 2. Produced.
【００４７】比較例３ エチレンカーボネート（ＥＣ）とメチルエチルカーボネ
ート（ＭＥＣ）との比率を体積比で１：１にした以外
は、比較例１と同様にして筒形の有機電解液二次電池を
作製した。Comparative Example 3 A cylindrical organic electrolyte secondary battery was prepared in the same manner as in Comparative Example 1 except that the ratio of ethylene carbonate (EC) to methyl ethyl carbonate (MEC) was changed to 1: 1 by volume. Produced.
【００４８】比較例４ 電極作製時に正極と負極との互いに対向した部分の単位
体積あたりの活物質含有合剤の正極／負極の重量比が
１．９５である電極を作製し、正極と負極の合計厚み、
渦巻状電極体の巻回径は同じにして、負極の充放電容量
が１３００ｍＡｈの電池を作製した以外は、比較例３と
同様にして筒形の有機電解液二次電池を作製した。負極
の充放電可能な容量は７９ｍＡｈ／ｃｍ3 であった。COMPARATIVE EXAMPLE 4 An electrode was prepared in which the weight ratio of the positive electrode / negative electrode of the active material-containing mixture per unit volume of the positive electrode and the negative electrode was 1.95 per unit volume of the positive electrode and the negative electrode at the time of electrode preparation. Total thickness,
A cylindrical organic electrolyte secondary battery was produced in the same manner as in Comparative Example 3, except that a spirally wound electrode body was made to have the same winding diameter and a negative electrode having a charge / discharge capacity of 1300 mAh was produced. The chargeable / dischargeable capacity of the negative electrode was 79 mAh / cm 3 .
【００４９】上記実施例１〜４および比較例１〜４の電
池を、１４００ｍＡで２．７５Ｖまで放電した後１４０
０ｍＡで充電し、４．１８Ｖに達した後は４．１８Ｖの
定電圧に保つ条件で２時間３０分の充電を行った。その
後、電池を４０℃の恒温槽に入れて２時間後に取り出
し、木製で溝をきった電池ホルダー上に置き、軸部の直
径が３ｍｍのステンレス鋼製の釘を電池の側面中心に直
角にかつ速やかに電池外径の１／２の深さまで刺し、異
常発熱の有無を調べた。その結果を表１に示す。After discharging the batteries of Examples 1 to 4 and Comparative Examples 1 to 4 to 2.75 V at 1400 mA, 140
After the battery was charged at 0 mA and reached 4.18 V, the battery was charged for 2 hours and 30 minutes under the condition of maintaining a constant voltage of 4.18 V. Thereafter, the battery was placed in a constant temperature bath at 40 ° C., taken out 2 hours later, placed on a wooden and grooved battery holder, and a stainless steel nail having a shaft diameter of 3 mm was perpendicular to the center of the side of the battery. Immediately, the battery was stabbed to a depth of の of the outer diameter of the battery to check for abnormal heat generation. Table 1 shows the results.
【００５０】この試験には実施例１〜４、比較例１〜４
の電池とも２０個ずつを用い、表１には試験に供した電
池個数を分母に示し、異常発熱のあった電池個数を分子
に示す態様で異常発熱の割合を示す。上記４０℃での１
／２釘刺し試験は安全性を確認する試験としてきわめて
苛酷な条件下での試験であり、この試験に５０％以上合
格すれば一定レベルの安全性を確保していると考えられ
る。Examples 1 to 4 and Comparative Examples 1 to 4
In Table 1, the number of batteries subjected to the test is shown in the denominator, and the number of batteries having abnormal heat generation is shown in the numerator, and the ratio of abnormal heat generation is shown in Table 1. 1 at 40 ° C
The / 2 nail penetration test is a test under extremely severe conditions as a test for confirming safety, and it is considered that a certain level of safety is secured if 50% or more of this test is passed.
【００５１】[0051]
【表１】 [Table 1]
【００５２】表１に示すように、実施例１〜４は、鎖状
エステルが５０体積％を超え電解液の主溶媒を構成して
いるが、異常発熱の割合が少なく、電解液中にアルキル
基を有する非イオン性芳香族化合物を含有させることに
よって釘刺し試験での安全性が向上することがわかる。
また、比較例２〜３のようにメチルエチルカーボネート
などの鎖状エステルが少なかったり、あるいは鎖状エス
テルがエチル基だけを有する場合には安全性がよく、ア
ルキル基を有する非イオン性芳香族化合物の添加の効果
は少なくなる傾向にある。さらに、比較例４のように負
極の充放電容量が小さい場合にも安全性が良くなり、ア
ルキル基を有する非イオン性芳香族化合物の添加の効果
は少なくなることがわかる。As shown in Table 1, in Examples 1 to 4, the chain ester exceeded 50% by volume and constituted the main solvent of the electrolytic solution. However, the rate of abnormal heat generation was small, and the alkyl ester was contained in the electrolytic solution. It can be seen that the inclusion of a nonionic aromatic compound having a group improves the safety in a nail penetration test.
In addition, when the number of chain esters such as methyl ethyl carbonate is small as in Comparative Examples 2 to 3, or when the chain ester has only an ethyl group, the safety is good, and the nonionic aromatic compound having an alkyl group is good. Tends to be less effective. Furthermore, even when the charge / discharge capacity of the negative electrode is small as in Comparative Example 4, the safety is improved, and the effect of adding the nonionic aromatic compound having an alkyl group is reduced.
【００５３】[0053]
【発明の効果】以上説明したように、本発明では、正
極、一部が電解液と反応して表面に皮膜が形成された負
極および鎖状エステルを主溶媒とする電解液を有する有
機電解液二次電池において、上記電解液にアルキル基を
有する非イオン性芳香族化合物を含有させることによっ
て、電池の安全性を改善することができた。特に負極の
充放電可能な容量が電池単位体積あたり８５ｍＡｈ／ｃ
ｍ3 を超える場合は安全性の向上効果が大きい。また、
アルキル基を有する非イオン性芳香族化合物としてトリ
−２−エチルヘキシルトリメリテートのようなベンゼン
環にＣＯＯ結合を介して長鎖のアルキル基が結合した化
合物を用いた場合は、安全性の向上効果が大きかった。As described above, the present invention provides an organic electrolyte comprising a positive electrode, a negative electrode having a film formed on the surface by partially reacting with the electrolyte, and an electrolyte having a chain ester as a main solvent. In a secondary battery, the safety of the battery could be improved by including a nonionic aromatic compound having an alkyl group in the electrolytic solution. In particular, the chargeable / dischargeable capacity of the negative electrode is 85 mAh / c per unit volume of the battery.
If more than m 3 greater effect of improving the safety. Also,
When a compound in which a long-chain alkyl group is bonded to a benzene ring via a COO bond such as tri-2-ethylhexyl trimellitate is used as the nonionic aromatic compound having an alkyl group, the effect of improving safety is improved. Was big.
【図面の簡単な説明】[Brief description of the drawings]
【図１】本発明に係る有機電解液二次電池の一例を模式
的に示す部分断面斜視図である。FIG. 1 is a partial sectional perspective view schematically showing an example of an organic electrolyte secondary battery according to the present invention.
１ 正極 ２ 負極 ３ セパレータ 1 positive electrode 2 negative electrode 3 separator
Claims (5)
に皮膜が形成された負極および鎖状エステルを主溶媒と
する有機電解液を有する有機電解液二次電池であって、
上記有機電解液がアルキル基を有する非イオン性芳香族
化合物を含有することを特徴とする有機電解液二次電
池。An organic electrolyte secondary battery comprising a positive electrode, a negative electrode having a film formed on its surface by partially reacting with an organic electrolyte, and an organic electrolyte having a chain ester as a main solvent,
An organic electrolyte secondary battery, wherein the organic electrolyte contains a nonionic aromatic compound having an alkyl group.
ステルであり、かつ、負極の充放電可能な容量が電池単
位体積あたり８５ｍＡｈ／ｃｍ3 以上であることを特徴
とする請求項１記載の有機電解液二次電池。2. The method according to claim 1, wherein the chain ester is a chain ester having a methyl group, and the chargeable / dischargeable capacity of the negative electrode is 85 mAh / cm 3 or more per unit volume of the battery. Organic electrolyte secondary battery.
合物が、炭素数５個以上のアルキル基を有する非イオン
性芳香族化合物であることを特徴とする請求項１記載の
有機電解液二次電池。3. The organic electrolyte secondary according to claim 1, wherein the nonionic aromatic compound having an alkyl group is a nonionic aromatic compound having an alkyl group having 5 or more carbon atoms. battery.
合物のアルキル基とベンゼン環とがＣＯＯ基を介して結
合していることを特徴とする請求項３記載の有機電解液
二次電池。4. The organic electrolyte secondary battery according to claim 3, wherein the alkyl group of the nonionic aromatic compound having an alkyl group and the benzene ring are bonded via a COO group.
合物がトリメリット酸エステルまたはその誘導体である
ことを特徴とする請求項４記載の有機電解液二次電池。5. The organic electrolyte secondary battery according to claim 4, wherein the nonionic aromatic compound having an alkyl group is trimellitic acid ester or a derivative thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09479897A JP3275998B2 (en) | 1997-03-28 | 1997-03-28 | Organic electrolyte secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09479897A JP3275998B2 (en) | 1997-03-28 | 1997-03-28 | Organic electrolyte secondary battery |
Related Child Applications (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001138198A Division JP3449703B2 (en) | 2001-05-09 | 2001-05-09 | Organic electrolyte secondary battery |
| JP2001200449A Division JP3247103B1 (en) | 2001-07-02 | 2001-07-02 | Organic electrolyte secondary battery |
| JP2001385375A Division JP3449706B2 (en) | 2001-12-19 | 2001-12-19 | Organic electrolyte secondary battery and charging method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10275632A true JPH10275632A (en) | 1998-10-13 |
| JP3275998B2 JP3275998B2 (en) | 2002-04-22 |
Family
ID=14120091
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP09479897A Expired - Lifetime JP3275998B2 (en) | 1997-03-28 | 1997-03-28 | Organic electrolyte secondary battery |
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| Country | Link |
|---|---|
| JP (1) | JP3275998B2 (en) |
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