JP2000348762A - Incombustible electrolyte and lithium secondary battery using it - Google Patents
Incombustible electrolyte and lithium secondary battery using itInfo
- Publication number
- JP2000348762A JP2000348762A JP11157489A JP15748999A JP2000348762A JP 2000348762 A JP2000348762 A JP 2000348762A JP 11157489 A JP11157489 A JP 11157489A JP 15748999 A JP15748999 A JP 15748999A JP 2000348762 A JP2000348762 A JP 2000348762A
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- electrolyte
- battery
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- 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
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は新規な電解液及びリ
チウム２次電池に関わり、特に、引火点をなくした不燃
性電解液の導電率の向上、及び、これを用いたリチウム
２次電池の電池容量及び電流特性の向上に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel electrolyte and a lithium secondary battery, and more particularly, to an improvement in the conductivity of a non-flammable electrolyte having no flash point and a lithium secondary battery using the same. It relates to improvement of battery capacity and current characteristics.
【０００２】[0002]
【従来の技術】リチウム２次電池は小型，軽量で、且
つ、高い電力容量を持つことから、携帯電話，パーソナ
ルコンピューター等の携帯用電気機器の電源として急速
に普及した。2. Description of the Related Art Lithium secondary batteries have been rapidly spread as power sources for portable electric devices such as mobile phones and personal computers because of their small size, light weight, and high power capacity.
【０００３】リチウム２次電池はその駆動電圧が４Ｖ以
上となるため、水を溶媒とする水系電解液はその耐電圧
性が不足するため使用できない。そこで、４Ｖ以上の駆
動でも分解することのない有機化合物を溶媒に用いた非
水電解液が使用されている。しかし、有機化合物の最大
の欠点はその可燃性の高さであり、これを用いることに
より電池が高温にさらされた場合に電解液の引火，燃焼
が懸念される。そこで、この問題を解決する手段とし
て、電解液に自己不燃性を有するフッ素化溶媒を混合
し、電解液を難燃化する技術が検討されている。例え
ば、特開平10−12272号公報では非水電解液中に、電解
液の特性を損なわない範囲（０.５ 〜３０重量％）で鎖
状分子構造のフッ素化アルカンまたはフッ素化エーテル
を混合することにより、電解液の引火点を５０℃以上と
する技術が開示されている。しかし、引火点が存在する
限りは、日常生活においてはまだ安全性に不安が残る。
この技術の最終目的としては、引火点のない不燃性電解
液にすべきと考える。しかしながら、フッ素化溶媒を用
いて不燃性とする場合、フッ素化溶媒のフッ素化数を増
やすか、または、電解液中の混合量を多くする必要があ
る。ところが、フッ素化溶媒のフッ素化数を高めると非
フッ素化溶媒との相溶性が大きく低下してしまい電解液
として調製できなくなる。また、フッ素化溶媒の混合量
を多くするとリチウム塩の溶解性が大幅に低下してしま
い、良好な導電性を確保することができない。[0003] Since the driving voltage of a lithium secondary battery is 4 V or more, an aqueous electrolyte using water as a solvent cannot be used because its withstand voltage is insufficient. Therefore, a non-aqueous electrolyte using an organic compound that does not decompose even when driven at 4 V or more is used as a solvent. However, the greatest drawback of organic compounds is their high flammability, which may cause ignition and combustion of the electrolyte when the battery is exposed to high temperatures. Therefore, as a means for solving this problem, a technique of mixing a fluorinated solvent having self-flammability with the electrolytic solution to make the electrolytic solution nonflammable has been studied. For example, in Japanese Patent Application Laid-Open No. 10-12272, a fluorinated alkane or fluorinated ether having a chain molecular structure is mixed in a nonaqueous electrolyte within a range (0.5 to 30% by weight) which does not impair the characteristics of the electrolyte. Accordingly, a technique has been disclosed in which the flash point of the electrolytic solution is set to 50 ° C. or higher. However, as long as the flash point exists, there is still concern about safety in daily life.
We believe that the ultimate goal of this technology should be a non-flammable electrolyte with no flash point. However, when using a fluorinated solvent to make it nonflammable, it is necessary to increase the number of fluorinations of the fluorinated solvent or to increase the mixing amount in the electrolyte. However, when the fluorination number of the fluorinated solvent is increased, the compatibility with the non-fluorinated solvent is greatly reduced, and the fluorinated solvent cannot be prepared as an electrolytic solution. In addition, when the mixing amount of the fluorinated solvent is increased, the solubility of the lithium salt is significantly reduced, and good conductivity cannot be secured.
【０００４】[0004]
【発明が解決しようとする課題】本発明の目的は、上記
の技術的な困難性の克服であり、電気特性（導電性）が
良好で、且つ、引火点のない不燃性電解液及び電池容量
及び電流特性の高いリチウム２次電池を提供するにあ
る。SUMMARY OF THE INVENTION An object of the present invention is to overcome the above technical difficulties, and to provide a non-flammable electrolyte and a battery having good electric characteristics (conductivity) and no flash point. Another object of the present invention is to provide a lithium secondary battery having high current characteristics.
【０００５】[0005]
【課題を解決するための手段】この課題は自己不燃性を
有するフッ素化溶媒として１，１，２，２，３，３，４
−ヘプタフルオロシクロペンタンを用いることにより解
決できる。この溶媒は化１The object of the present invention is to provide a self-flammable fluorinated solvent such as 1,1,2,2,3,3,4.
The problem can be solved by using heptafluorocyclopentane. This solvent is
【０００６】[0006]
【化１】 Embedded image
【０００７】に示す環状の分子構造を有し、且つ、部分
的にフッ素化されていない部分が存在するため、分子の
極性が高くなっており、電解液の誘電率の低下が少なく
なって、導電率の低下が抑制される。即ち、フッ素化溶
媒の混合量を多くした組成においても導電率の低下が少
なくなる次第である。また、不燃性であり導電率の高い
電解液を用いることにより、電解液の引火や燃焼の危険
が回避され、且つ、従来の不燃性あるいは難燃性の電解
液を用いたリチウム２次電池に比べ負荷特性を向上する
ことができる。[0007] Since there is a portion that has a cyclic molecular structure shown in (1) and is not partially fluorinated, the polarity of the molecule is high, and the decrease in the dielectric constant of the electrolyte is small. A decrease in conductivity is suppressed. That is, even in a composition in which the mixing amount of the fluorinated solvent is increased, the decrease in the conductivity is gradually reduced. In addition, by using a non-flammable and highly conductive electrolyte, danger of ignition and burning of the electrolyte can be avoided, and a conventional lithium secondary battery using a non-flammable or non-flammable electrolyte can be used. The load characteristics can be improved in comparison.
【０００８】（電解液）電解液を引火点のない不燃性溶
液とするためのフッ素化溶媒として、１，１，２，２，
３，３，４−ヘプタフルオロシクロペンタン（以下ＨＦ
ＣＰと略記する）を必須成分として用いる。また、フッ
素化率が７０％以上のフッ素化アルカン、例えば、Ｃ6
Ｆ14，Ｃ7Ｆ16，Ｃ8Ｆ18 等をＨＦＣＰと混合して用い
ることができる。また、電解質を溶解，解離させる非フ
ッ素化溶媒には、エチレンカーボネート，プロピレンカ
ーボネート，ジメチルカーボネート，エチルメチルカー
ボネート，ジエチルカーボネート等の極性の高い溶媒を
用いることができる。また、リチウム塩にはＬｉＰ
Ｆ6 ，ＬｉＢＦ4 ，ＬｉＣｌＯ4 等を用いることができ
るが、安全性の点からＬｉＰＦ6 またはＬｉＢＦ4 を用
いるのが望ましい。(Electrolyte) As a fluorinated solvent for converting an electrolyte into a nonflammable solution having no flash point, 1,1,2,2,2
3,3,4-heptafluorocyclopentane (hereinafter HF)
CP) is used as an essential component. A fluorinated alkane having a fluorination rate of 70% or more, for example, C 6
F 14 , C 7 F 16 , C 8 F 18 and the like can be used as a mixture with HFCP. As the non-fluorinated solvent that dissolves and dissociates the electrolyte, a highly polar solvent such as ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate can be used. The lithium salt is LiP
F 6 , LiBF 4 , LiClO 4 or the like can be used, but it is preferable to use LiPF 6 or LiBF 4 from the viewpoint of safety.
【０００９】（電極・セパレータ）正極材料，負極材料
は特に限定する必要はない。正極材料にはＬｉＣｏＯ2
やＬｉＭｎ2Ｏ4，ＬｉＮｉＯ2 等を好適に用いることが
できる。負極には、難黒鉛性炭素または天然，人造の黒
鉛炭素、或いは、リチウム金属またはリチウム合金等を
用いることができる。セパレータには微多孔性の高分子
フィルムを用いることができる。例えば、ナイロン，セ
ルロース，ニトロセルロース，ポリスルホン，ポリアク
リロニトリル，ポリフッ化ビニリデン，ポリプロピレ
ン，ポリエチレン，モリブテン等が挙げられる。(Electrode / Separator) The material of the positive electrode and the material of the negative electrode need not be particularly limited. LiCoO 2 for the cathode material
And LiMn 2 O 4 , LiNiO 2 and the like can be suitably used. For the negative electrode, non-graphitizable carbon, natural or artificial graphite carbon, lithium metal, lithium alloy, or the like can be used. A microporous polymer film can be used for the separator. Examples include nylon, cellulose, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polypropylene, polyethylene, molybdenum and the like.
【００１０】[0010]
【発明の実施の形態】本発明を実施例によりさらに詳細
に説明する。尚、本発明は以下の実施例に限定されるも
のではない。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail by way of examples. The present invention is not limited to the following embodiments.
【００１１】（比較例１）フッ素化溶媒としてＣ6Ｆ14
を７０容量％，ジエチルカーボネートを３０容量％混合
した溶媒を調製した。JIS2265 に準拠したクリーブラン
ド開放式の引火試験による評価で、この混合溶媒の引火
点はなかった。この溶媒にＬｉＰＦ6 を可溶限界であっ
た０.１モル／リッター まで溶解し、比較例１の電解液
１を調製した。この電解液の交流１０ｋＨｚで測定した
導電率は０.１ｍＳ／cm であった。この様に、従来公開
されているフッ素化溶媒を混合溶媒の引火点がなくなる
範囲まで増加すると、リチウム塩の溶解性が極端に低下
し、電解液の導電率が低くなってしまう。(Comparative Example 1) C 6 F 14 as a fluorinated solvent
Was prepared by mixing 70% by volume and 30% by volume of diethyl carbonate. In the evaluation by a Cleveland open-type flash test based on JIS2265, there was no flash point of this mixed solvent. LiPF 6 was dissolved in this solvent to a solubility limit of 0.1 mol / liter to prepare an electrolyte solution 1 of Comparative Example 1. The conductivity of this electrolyte measured at an alternating current of 10 kHz was 0.1 mS / cm 2. As described above, when the conventionally disclosed fluorinated solvent is increased to a range where the flash point of the mixed solvent is eliminated, the solubility of the lithium salt is extremely reduced, and the conductivity of the electrolytic solution is reduced.
【００１２】（実施例１）フッ素化溶媒としてＨＦＣＰ
（１，１，２，２，３，３，４−ヘプタフルオロシクロ
ペンタン）を２０容量％、Ｃ6Ｆ14 を５０容量％、ジエ
チルカーボネートを３０容量％混合した溶媒を調製し
た。この混合溶媒はＪＩＳ２２６５に準拠したクリーブ
ランド開放式の引火試験による評価の結果、引火点はな
かった。この溶媒に対するＬｉＰＦ6 の溶解性を調べた
結果、０．２モル／リッターまで溶解させることができ
た。即ち、比較例１に対して２倍のリチウム塩を溶解さ
せることができ、ＨＦＣＰが良好な溶解促進の作用を有
することが分かった。次に、このリチウム塩濃度で実施
例１の電解液Ａを調製した。この電解液Ａの交流１０ｋ
Ｈｚにおける導電率は０.３ｍＳ／cm に達していた。こ
の様に、従来公開されているフッ素化溶媒を用いた不燃
性電解液にＨＦＣＰをそれよりも低い割合で混合するこ
とによって、リチウム塩の溶解性を濃度にして２倍に高
めることができ、且つ、導電率を０.２ｍＳ／cm も高く
することができた。以上の様に、HFCPをＣ6Ｆ14 に混合
して用いることによって引火点のない程度フッ素化溶媒
を大量に含む電解液の導電率を、不燃性を損なうことな
く改善することができた。Example 1 HFCP as fluorinated solvent
(1,1,2,2,3,3,4-heptafluoro cyclopentane) 20 volume%, the C 6 F 14 50 volume% to prepare a mixed solvent of diethyl carbonate 30% by volume. This mixed solvent had no flash point as a result of evaluation by a Cleveland open-type flash test according to JIS2265. As a result of examining the solubility of LiPF 6 in this solvent, it was possible to dissolve LiPF 6 up to 0.2 mol / liter. That is, it was found that twice as much lithium salt as in Comparative Example 1 could be dissolved, and that HFCP had a good dissolution promoting action. Next, the electrolyte solution A of Example 1 was prepared at this lithium salt concentration. AC 10k of this electrolyte A
The conductivity at Hz reached 0.3 mS / cm 2. As described above, by mixing HFCP with a conventionally disclosed nonflammable electrolyte using a fluorinated solvent at a lower ratio, the solubility of the lithium salt can be increased by a factor of two, In addition, the conductivity was increased by 0.2 mS / cm 2. As described above, by mixing HFCP with C 6 F 14 , the conductivity of the electrolyte containing a large amount of the fluorinated solvent without flash point could be improved without impairing the nonflammability.
【００１３】（実施例２）フッ素化溶媒としてＨＦＣＰ
（１，１，２，２，３，３，４−ヘプタフルオロシクロ
ペンタン）を４０容量％，Ｃ6Ｆ14 を４０容量％，ジエ
チルカーボネートを２０容量％混合した溶媒を調製し
た。この混合溶媒もJIS2265 に準拠したクリーブランド
開放式の引火試験による評価で、引火点のないことを確
認した。この溶媒に対するＬｉＰＦ6 の溶解性を調べた
結果、０.３モル／リッター まで溶解させることができ
た。この濃度で実施例２の電解液Ｂを調製した。電解液
Ｂの交流１０ｋＨｚにおける導電率は更に向上し、０.
８ｍＳ／cm に達していた。この様に、不燃性電解液に
おけるフッ素化溶媒の混合量を増やし、可燃性の高いジ
エチルカーボネートの混合量を低減した組成、即ち、リ
チウム塩を溶解させにくい組成においても、比較例１の
電解液１に対してリチウム塩の溶解性を濃度にして３倍
に高くすることができ、且つ、導電率を０.７ｍＳ／cm
も高くすることができた。以上の様に、ＨＦＣＰを従来
公開されているフッ素化溶媒と同割合で混合することに
より、引火点のない不燃性を損なうことなく、飛躍的に
導電率を更に向上することができた。Example 2 HFCP as fluorinated solvent
(1,1,2,2,3,3,4-heptafluoro cyclopentane) 40 volume%, C 6 F 14 to 40 vol%, to prepare a mixed solvent of diethyl carbonate 20% by volume. This mixed solvent was evaluated by a Cleveland open-type flash test in accordance with JIS2265, and it was confirmed that there was no flash point. As a result of examining the solubility of LiPF 6 in this solvent, it was possible to dissolve LiPF 6 up to 0.3 mol / liter. At this concentration, the electrolytic solution B of Example 2 was prepared. The conductivity of the electrolyte B at an alternating current of 10 kHz is further improved, and
8 mS / cm 2 had been reached. Thus, even in a composition in which the mixing amount of the fluorinated solvent in the non-flammable electrolyte is increased and the mixing amount of the highly flammable diethyl carbonate is reduced, that is, in the composition in which the lithium salt is hardly dissolved, the electrolyte of Comparative Example 1 The solubility of the lithium salt can be increased by a factor of 3 with respect to 1, and the conductivity is 0.7 mS / cm.
Could also be higher. As described above, by mixing HFCP with the fluorinated solvent disclosed in the prior art in the same ratio, the conductivity can be further improved dramatically without impairing the nonflammability having no flash point.
【００１４】（実施例３）フッ素化溶媒としてＨＦＣＰ
を９０容量％，エチレンカーボネートを１０容量％混合
した溶媒を調製した。この溶媒をJIS2265 に準拠したク
リーブランド開放式の引火試験により評価した結果、引
火点はなかった。この溶媒に対するLiPF6の溶解性を調
べた結果、０.１モル／リッター まで溶解させることが
できた。この濃度で実施例３の電解液Ｃを調製した。電
解液Ｃの交流１０ｋＨｚにおける導電率は１.３６ｍＳ
／cm であった。驚くべきことに、ＨＦＣＰは従来公開
されているフッ素化溶媒ではリチウム塩の溶解性が殆ど
なくなる９０容量％という高い混合量の組成において、
リチウム塩の溶解濃度は低いものの導電率は比較例１の
電解液１(０.３ｍＳ／cm)に比べ４倍以上も高い数値
（１.３６ｍＳ／cm）を示した。この様にＨＦＣＰは配
合量の高い領域、即ち、自己不燃性の溶媒が大量に存在
する組成においても、従来公開されているフッ素化溶媒
を用いた電解液に比べて高い導電性を確保することがで
きる。また、ＨＦＣＰを５０容量％以下で用い、不燃性
を確保するために従来公開されているフッ素化溶媒と混
合して用いた実施例１及び実施例２の電解液Ａ及び電解
液Ｂに比べて、導電率はそれぞれ１ｍＳ／cm、及び、
０.５ｍＳ／cm も向上した。Example 3 HFCP as fluorinated solvent
Was prepared by mixing 90% by volume and 10% by volume of ethylene carbonate. This solvent was evaluated by a Cleveland open-type flash test based on JIS2265, and as a result, there was no flash point. As a result of examining the solubility of LiPF 6 in this solvent, it was possible to dissolve LiPF 6 up to 0.1 mol / liter. At this concentration, the electrolytic solution C of Example 3 was prepared. The conductivity of the electrolyte C at an alternating current of 10 kHz is 1.36 mS.
/ Cm 2. Surprisingly, HFCP has a high loading of 90% by volume, where the solubility of the lithium salt in conventional fluorinated solvents is negligible.
Although the dissolution concentration of the lithium salt was low, the conductivity showed a value (1.36 mS / cm) which was at least four times higher than that of the electrolyte 1 of Comparative Example 1 (0.3 mS / cm). As described above, HFCP ensures a higher conductivity than a conventionally disclosed electrolyte solution using a fluorinated solvent even in a region where the amount of HFCP is high, that is, in a composition in which a large amount of a self-flammable solvent is present. Can be. Further, as compared with the electrolytes A and B of Examples 1 and 2 in which HFCP was used at 50% by volume or less and mixed with a conventionally disclosed fluorinated solvent to ensure nonflammability. , The conductivity is 1 mS / cm, respectively, and
It also improved by 0.5 mS / cm 2.
【００１５】（実施例４）フッ素化溶媒としてＨＦＣＰ
を７０容量％、エチレンカーボネートを３０容量％混合
した溶媒を調製した。この溶媒をJIS2265 に準拠したク
リーブランド開放式の引火試験により評価した結果、引
火点はなかった。この溶媒に対するＬｉＰＦ６の溶解性
を調べた結果、０．５ モル／リッターまで溶解させる
ことができた。この濃度で実施例４の電解液Ｄを調製し
た。電解液Ｄの交流１０ｋＨｚにおける導電率は３.３
ｍＳ／cm であった。この様に、ＨＦＣＰは消火性も高
く７０容量％の混合量でも引火点はなく、非フッ素化溶
媒の混合量を増やせるために、リチウム塩の溶解量が実
施例３の電解液Ｃに比べても５倍に高くすることがで
き、導電率を２ｍＳ／cm も向上させることができるこ
とが分かった。Example 4 HFCP as fluorinated solvent
Was mixed with 70% by volume of ethylene carbonate and 30% by volume of ethylene carbonate to prepare a solvent. This solvent was evaluated by a Cleveland open-type flash test based on JIS2265, and as a result, there was no flash point. As a result of examining the solubility of LiPF 6 in this solvent, it was possible to dissolve LiPF 6 up to 0.5 mol / liter. At this concentration, the electrolytic solution D of Example 4 was prepared. The conductivity of the electrolyte D at an alternating current of 10 kHz is 3.3.
mS / cm 2. As described above, HFCP has a high fire extinguishing property and has no flash point even at a mixing amount of 70% by volume, and the amount of the lithium salt dissolved is smaller than that of the electrolyte solution C of Example 3 in order to increase the mixing amount of the non-fluorinated solvent. Was also increased by a factor of 5 and the conductivity was improved by 2 mS / cm 2.
【００１６】（実施例５）そこで、更にＨＦＣＰの量を
低減した組成を検討した。フッ素化溶媒としてＨＦＣＰ
を５０容量％、エチレンカーボネートを５０容量％混合
した溶媒を調製した。この様に低いＨＦＣＰの配合量の
混合溶媒でも、JIS2265 に準拠したクリーブランド開放
式の引火試験で引火点がなかった。この溶媒に対するＬ
ｉＰＦ6の溶解性を調べた結果、１.０モル／リッター
まで溶解させることができた。この濃度で実施例５の電
解液Ｅを調製した。電解液Ｃの交流１０ｋＨｚにおける
導電率は５.１ｍＳ／cm と驚異的に向上していた。この
様に、ＨＦＣＰとエチレンカーボネートを混合しただけ
の簡単な組成であっても、ＨＦＣＰを５０容量％混合す
ることにより電解液溶媒を不燃化でき、且つ、比較例１
の電解液１に比べてリチウム塩の溶解濃度を１０倍，導
電率を５０倍以上に向上することができた。また、実施
例４の電解液Ｄに比べても、非フッ素化溶媒の配合量を
増加させることができたために、リチウム塩濃度を２
倍、導電率を１.７ｍＳ／cm 向上させることができた。Example 5 Therefore, a composition in which the amount of HFCP was further reduced was studied. HFCP as fluorinated solvent
Was mixed with 50% by volume of ethylene carbonate and 50% by volume of ethylene carbonate. Even with the mixed solvent having such a low HFCP content, there was no flash point in the Cleveland open-type flash test according to JIS2265. L for this solvent
The results of investigating the solubility of iPF 6, 1.0 mol / liter
Could be dissolved. At this concentration, the electrolyte solution E of Example 5 was prepared. The conductivity of the electrolyte C at an alternating current of 10 kHz was astonishingly improved to 5.1 mS / cm. Thus, even with a simple composition in which HFCP and ethylene carbonate are simply mixed, the electrolyte solvent can be made nonflammable by mixing 50% by volume of HFCP, and Comparative Example 1
As compared with the electrolytic solution 1 of Example 1, the dissolution concentration of the lithium salt was improved to 10 times and the conductivity was improved to 50 times or more. Also, compared to the electrolyte solution D of Example 4, the compounding amount of the non-fluorinated solvent could be increased.
As a result, the conductivity was improved by 1.7 mS / cm.
【００１７】以上の様に、ＨＦＣＰはこれまで公開され
たフッ素化溶媒と異なり、誘電率及び引火点の高い環状
カーボネートを単独で広い範囲で相溶することができる
ため、ＨＦＣＰを５０容量％以上混合することによって
溶媒を不燃化でき、且つ、これらの溶媒の高い極性によ
りリチウム塩を多量に溶解でき、導電率の向上した不燃
性電解液を得ることができる。As described above, unlike fluorinated solvents disclosed so far, HFCP can independently dissolve a cyclic carbonate having a high dielectric constant and a high flash point in a wide range. By mixing, the solvent can be made nonflammable, and the high polarity of these solvents can dissolve a large amount of the lithium salt, so that a nonflammable electrolyte having improved conductivity can be obtained.
【００１８】（実施例６）次に、鎖状カーボネートを混
合した３成分系の溶媒を検討した。フッ素化溶媒として
ＨＦＣＰを７０容量％，エチレンカーボネートを２７容
量％，ジメチルカーボネートを３容量％混合した溶媒を
調製した。鎖状カーボネートはそれ自体の引火点が低い
ため多量に混合することはできないが、この組成の混合
溶媒では引火点はなかった。この溶媒に対するＬｉＰＦ
6 の溶解性を調べた結果、ＨＦＣＰの配合量が同一の実
施例４の電解液Ｄと同じ濃度、０.５モル／リッター ま
で溶解させることができた。この濃度で実施例６の電解
液Ｆを調製した。電解液Ｆの交流１０ｋＨｚにおける導
電率は３.４ｍＳ／cm であった。この様に、ジメチルカ
ーボネートを少量配合することによって引火点のない電
解液の導電率を更に向上することができた。Example 6 Next, a three-component solvent mixed with a chain carbonate was examined. As a fluorinated solvent, a solvent was prepared by mixing 70% by volume of HFCP, 27% by volume of ethylene carbonate, and 3% by volume of dimethyl carbonate. The chain carbonate itself cannot be mixed in large quantities because of its low flash point, but the mixed solvent of this composition did not have a flash point. LiPF for this solvent
As a result of examining the solubility of No. 6 , the compound was able to be dissolved up to the same concentration and 0.5 mol / liter as the electrolytic solution D of Example 4 having the same compounding amount of HFCP. At this concentration, the electrolytic solution F of Example 6 was prepared. The conductivity of the electrolyte F at an alternating current of 10 kHz was 3.4 mS / cm 2. As described above, by adding a small amount of dimethyl carbonate, it was possible to further improve the conductivity of the electrolyte solution having no flash point.
【００１９】（実施例７）次に、鎖状カーボネートの種
類を変えた溶媒系を検討した。フッ素化溶媒としてＨＦ
ＣＰを７０容量％，エチレンカーボネートを２５容量
％，エチルメチルカーボネートを５容量％混合した溶媒
を調製した。エチルメチルカーボネートはデメチルカー
ボネートよりも蒸気圧が低いためにこの配合量まで混合
しても引火点はなかった。この溶媒に対するＬｉＰＦ6
の溶解性を調べた結果、０.５モル／リッターまで溶解
させることができた。この濃度で実施例７の電解液Ｇを
調製した。この電解液Ｇの交流１０ｋＨｚにおける導電
率は３.５ｍＳ／cm であった。エチルメチルカーボネー
トでは、引火点のない範囲でその配合量を更に増やせた
ことにより、導電率を実施例６の電解液Ｆに比べ更に
０.１ｍＳ／cm 向上することができた。(Example 7) Next, a solvent system in which the type of the chain carbonate was changed was examined. HF as fluorinated solvent
A solvent was prepared by mixing 70% by volume of CP, 25% by volume of ethylene carbonate, and 5% by volume of ethyl methyl carbonate. Since ethyl methyl carbonate has a lower vapor pressure than demethyl carbonate, there was no flash point when mixed up to this amount. LiPF 6 for this solvent
As a result of examining the solubility of the compound, the compound could be dissolved up to 0.5 mol / liter. At this concentration, the electrolyte solution G of Example 7 was prepared. The conductivity of the electrolytic solution G at an alternating current of 10 kHz was 3.5 mS / cm 2. In the case of ethyl methyl carbonate, the conductivity could be further improved by 0.1 mS / cm as compared with the electrolytic solution F of Example 6 by further increasing the compounding amount within a range having no flash point.
【００２０】（実施例８）フッ素化溶媒としてＨＦＣＰ
を７０容量％，エチレンカーボネートを２３容量％，ジ
エチルカーボネートを７容量％混合した溶媒を調製し
た。ジエチルカーボネートはエチルメチルカーボネート
よりも更に蒸気圧が低いので、この組成でも引火点はな
かった。この溶媒に対するＬｉＰＦ6 の溶解性を調べた
結果、０.５モル／リッターまで溶解させることができ
た。この濃度で実施例８の電解液Ｈを調製した。この電
解液Ｈの交流１０ｋＨｚにおける導電率は３.６ｍＳ／c
m であった。これは、実施例７の電解液Ｇに比べ更に
０.１ｍＳ／cm 高い値となっている。以上の様に、ＨＦ
ＣＰの配合量が５０容量％以上の高い組成において、鎖
状カーボネートを加えた３成分系の溶媒にすることによ
って、同一のＨＦＣＰ配合量において導電率を更に向上
させることができる。また、ＨＦＣＰは５０容量％以上
配合量の組成において、フッ素溶媒として単独で用いて
も引火点をなくす作用と導電率を高める作用を有するこ
とが分かった。従って、ＨＦＣＰを用いて不燃性電解液
を得るには５０容量％以上の配合量における使用がより
効果的である。Example 8 HFCP as fluorinated solvent
, 70% by volume of ethylene carbonate, 23% by volume of ethylene carbonate, and 7% by volume of diethyl carbonate were prepared. Diethyl carbonate had a lower vapor pressure than ethyl methyl carbonate, so there was no flash point at this composition. As a result of examining the solubility of LiPF 6 in this solvent, it was possible to dissolve LiPF 6 up to 0.5 mol / liter. At this concentration, the electrolyte solution H of Example 8 was prepared. The conductivity of the electrolyte H at an alternating current of 10 kHz is 3.6 mS / c.
m. This is a value 0.1 mS / cm higher than that of the electrolyte solution G of Example 7. As described above, HF
In a composition having a high CP content of 50% by volume or more, the conductivity can be further improved at the same HFCP content by using a ternary solvent to which a chain carbonate is added. In addition, it was found that HFCP has a function of eliminating a flash point and a function of increasing conductivity even when used alone as a fluorine solvent in a composition having a blending amount of 50% by volume or more. Therefore, in order to obtain a non-combustible electrolyte using HFCP, it is more effective to use a compounding amount of 50% by volume or more.
【００２１】（比較例２）比較例１で作製した電解液１
（即ち、フッ素化溶媒としてＣ6Ｆ14 を７０容量％、ジ
エチルカーボネートを３０容量％混合した溶媒に、Ｌｉ
ＰＦ6を０.１モル／リッター溶解した組成の電解液）を
用いて図１に示す円筒型の電池を作製し、電池容量を評
価した。以下にこの作製方法を示す。負極材料とした人
造黒鉛を９０重量％、結着剤としたポリビニリデンフロ
ライド（ＰＶＤＦ）を１０重量％の割合で塗布溶媒Ｎ−
メチルピロリドン（ＮＭＰ）に溶解後、十分に混練し負
極材のペーストを得た。このペーストを幅５６mm，長さ
４６０mm（タブ端子溶接部を２０mm残す），厚み２５μ
ｍの集電体として用いた銅箔１の両面に塗布，乾燥し、
ローラーでプレスし、更に、真空乾燥して負極層２を形
成した。更に、この負極の未塗布部に幅５mmのニッケル
箔で負極タブ端子３を電気溶接により成形した。正極材
料であるＬｉＣｏＯ2 を８５重量％、導電助剤としたア
セチレンブラックを８重量％、結着剤としたＰＶＤＦを
７重量％の割合で塗布溶媒ＮＭＰに溶解後、十分に混練
し正極材のペーストを得た。この正極ペーストを幅５５
mm，長さ４４０mm（タブ端子溶接部を４０mm残す），厚
み２０μｍの集電体として用いたアルミ箔４の両面に塗
布，乾燥し、ローラーでプレスし、更に、真空乾燥して
正極層５を形成した。更に、この正極の未塗布部に幅５
mmのニッケル箔で正極タブ端子６を電気溶接により形成
した。これら負極と正極を、セパレータを介して捲回し
て電極群を形成した。この電極群を、負極タブ端子３を
缶底にして電池缶９にポリイミド製のインシュレータ８
を挟んで挿入し、缶底に負極タブ端子３を電気溶接して
接続した。また、正極タブ端子６は、インシュレータ１
２を介して、ゴム製ガスケット１０を蓋外周に具備した
正極蓋１１の電池側内向面に電気溶接して接続した。次
に、先に調製した比較例１の電解液１を真空注液機によ
り約３.５ｍｌ 注入し、正極蓋１１を電池缶９に挿入
し、カシメ機により電池缶９をカシメて比較例２の電池
１を得た。(Comparative Example 2) Electrolyte 1 prepared in Comparative Example 1
(That is, a solvent in which 70% by volume of C 6 F 14 and 30% by volume of diethyl carbonate are mixed as a fluorinated solvent is mixed with Li
The PF 6 was prepared cylindrical battery shown in FIG. 1 with 0.1 electrolyte mol / liter dissolved composition) was evaluated for battery capacity. The manufacturing method will be described below. 90% by weight of artificial graphite as a negative electrode material and 10% by weight of polyvinylidene fluoride (PVDF) as a binder were used as coating solvents N-.
After dissolving in methylpyrrolidone (NMP), the mixture was sufficiently kneaded to obtain a paste of a negative electrode material. This paste is 56mm in width, 460mm in length (leave 20mm at the tab terminal weld), 25μ in thickness
m, applied and dried on both sides of the copper foil 1 used as a current collector,
The negative electrode layer 2 was formed by pressing with a roller and further drying under vacuum. Further, a negative electrode tab terminal 3 was formed by electric welding with a nickel foil having a width of 5 mm on an uncoated portion of the negative electrode. After dissolving 85% by weight of LiCoO 2 as a positive electrode material, 8% by weight of acetylene black as a conductive additive, and 7% by weight of PVDF as a binder in a coating solvent NMP, the mixture was sufficiently kneaded to obtain a positive electrode material. A paste was obtained. This positive electrode paste is
mm, length 440 mm (leaving 40 mm for the tab terminal weld), coating and drying on both sides of aluminum foil 4 used as a current collector having a thickness of 20 μm, pressing with a roller, and further drying in vacuum to form positive electrode layer 5 Formed. In addition, a width of 5
The positive electrode tab terminal 6 was formed by electric welding with a nickel foil of mm. These negative and positive electrodes were wound via a separator to form an electrode group. This electrode group is placed in a battery can 9 with the negative electrode tab terminal 3 as the bottom of the can, and a polyimide insulator 8
The negative electrode tab terminal 3 was connected to the bottom of the can by electric welding. The positive electrode tab terminal 6 is connected to the insulator 1
2, a rubber gasket 10 was electrically welded and connected to the battery-side inward surface of the positive electrode lid 11 provided on the outer periphery of the lid. Next, about 3.5 ml of the electrolyte solution 1 of Comparative Example 1 prepared above was injected using a vacuum injection machine, the positive electrode lid 11 was inserted into the battery can 9, and the battery can 9 was caulked with a caulking machine. Battery 1 was obtained.
【００２２】この電池を電流値１００ｍＡ定電流、４.
１Ｖ 定電圧で終止電流値３０ｍＡの条件で充電し、定
電流１００ｍＡで終止電圧２.８Ｖ の条件で放電した。
この時の放電容量は８００ｍＡｈであった。次に、電流
値を１Ａとして他は同じ条件で、充放電した。この電流
値での放電容量は３００ｍＡｈとなった。従って、電池
１の１Ａでの１００ｍＡに対する容量維持率は３８％で
あった。この様に、従来のフッ素化溶媒ではこれを多量
に用いて引火点を無くした組成では、電池の放電容量が
低く、また、大電流で放電した際の容量の低下が激しい
という問題がある。The battery was supplied with a constant current of 100 mA, 4.
The battery was charged at a constant current of 30 mA at a constant voltage of 1 V and discharged at a constant voltage of 2.8 V at a constant current of 100 mA.
The discharge capacity at this time was 800 mAh. Next, charging and discharging were performed under the same conditions except that the current value was 1 A. The discharge capacity at this current value was 300 mAh. Therefore, the capacity retention ratio of the battery 1 to 100 mA at 1 A was 38%. As described above, in a composition in which the flash point is eliminated by using a large amount of the conventional fluorinated solvent, there is a problem that the discharge capacity of the battery is low, and the capacity is greatly reduced when discharged at a large current.
【００２３】（実施例９）次に、電解液として実施例１
で作製した電解液Ａ（即ち、ＨＦＣＰを２０容量％，Ｃ
6Ｆ14 を５０容量％、ジエチルカーボネートを３０容量
％混合した溶媒にＬｉＰＦ6を０.２モル／リッター溶解
した電解液）を用いて、比較例２で示したと同じ仕様の
実施例９の電池Ａを、上記と同様の方法で作製し、電池
の充放電特性を評価した。この電池の１００ｍＡでの放
電容量は１０３０ｍＡｈで、比較例２の電池１よりも２
３０ｍＡｈも放電容量が向上していた。また、１Ａでの
放電容量は５７０ｍＡｈあり、１Ａで比較すると放電容
量は２７０ｍＡｈもの容量の向上が見られた。また、容
量維持率は５８％であり、比較例２の電池１に比べて１
７％もの向上が認められる。この様に、ＨＦＣＰを混合
し導電率を向上した電解液を用いることにより、電池の
放電容量が改善され、更に、大電流に対する容量維持率
も大幅に改善されることが分かった。(Example 9) Next, Example 1 was used as an electrolyte.
Electrolyte A prepared in the above (ie, HFCP is 20% by volume, C
The battery of Example 9 having the same specifications as Comparative Example 2 using an electrolyte solution in which LiPF 6 was dissolved in a solvent in which 6 F 14 was mixed with 50% by volume of diethyl carbonate and 30% by volume of diethyl carbonate and LiPF 6 was dissolved at 0.2 mol / liter. A was prepared in the same manner as above, and the charge / discharge characteristics of the battery were evaluated. The discharge capacity at 100 mA of this battery was 1030 mAh, which was 2 times higher than that of the battery 1 of Comparative Example 2.
The discharge capacity was improved by 30 mAh. In addition, the discharge capacity at 1A was 570 mAh, and the discharge capacity was improved by as much as 270 mAh as compared with 1A. In addition, the capacity retention ratio was 58%, which was 1 compared with the battery 1 of Comparative Example 2.
An improvement of as much as 7% is observed. As described above, it was found that the use of the electrolytic solution mixed with HFCP to improve the electric conductivity improved the discharge capacity of the battery and further improved the capacity retention rate for a large current.
【００２４】（実施例１０）次に、電解液として実施例
２で作製した電解液Ｂ（即ち、ＨＦＣＰを４０容量％，
Ｃ6Ｆ14 を４０容量％，ジエチルカーボネートを２０容
量％混合した溶媒にＬｉＰＦ6を０.３モル／リッター溶
解した電解液）を用いて、同じ仕様の実施例１０の電池
Ｂを、上記と同様の方法で作製し、電池の充放電特性を
評価した。この電池の１００ｍＡでの放電容量は１１２
０ｍＡｈで、比較例２の電池１よりも３２０ｍＡｈも放
電容量が向上した。また、１Ａでの放電容量は７４０ｍ
Ａｈあり、１Ａで比較すると放電容量は４４０ｍＡｈも
向上していることが分かった。また、容量維持率は６６
％であり、比較例２の電池１に比べて２８％も向上し
た。これらの数値は、実施例９の電池Ａに対しても、１
００ｍＡで９０ｍＡｈ，１Ａで１７０ｍＡｈの放電容量
の向上になっており、電流値の高い動作での放電容量が
大幅に向上している。また、維持率で比較すると１１％
もの向上となっている。Example 10 Next, the electrolytic solution B prepared in Example 2 (that is, HFCP was 40% by volume,
The battery B of Example 10 having the same specifications as described above was prepared using an electrolyte in which LiPF 6 was dissolved in a solvent in which C 6 F 14 was mixed at 40% by volume and diethyl carbonate at 20% by volume in a concentration of 0.3 mol / liter. The battery was manufactured in the same manner, and the charge and discharge characteristics of the battery were evaluated. The discharge capacity at 100 mA of this battery was 112.
At 0 mAh, the discharge capacity was improved by 320 mAh compared to the battery 1 of Comparative Example 2. The discharge capacity at 1 A is 740 m.
Ah, it was found that the discharge capacity was improved by 440 mAh as compared with 1 A. The capacity retention rate is 66
%, Which is 28% higher than the battery 1 of Comparative Example 2. These values are also 1 for the battery A of Example 9.
The discharge capacity is improved by 90 mAh at 00 mA and 170 mAh at 1 A, and the discharge capacity in operation with a high current value is greatly improved. 11% compared to the maintenance rate
Things have improved.
【００２５】以上の様に、ＨＦＣＰを不燃性電解液のフ
ッ素化溶媒として用いることによって、フッ素化溶媒を
多量に含有する電解液の欠点であった容量の低下と電流
値に対する容量低下、所謂、負荷特性を大幅に改善でき
ることが示された。As described above, by using HFCP as a fluorinated solvent for a nonflammable electrolyte, a decrease in capacity and a decrease in capacity with respect to a current value, which are drawbacks of an electrolyte containing a large amount of fluorinated solvent, are so-called. It was shown that the load characteristics could be greatly improved.
【００２６】（実施例１１）次に、電解液として実施例
３で作製した電解液Ｃ（即ち、ＨＦＣＰを９０容量％、
エチレンカーボネートを１０容量％混合した溶媒にＬｉ
ＰＦ6 を０.１ モル／リッター溶解した電解液）を用い
て、同じ仕様の実施例１１の電池Ｃを、同様の方法で作
製し、電池の充放電特性を評価した。この電池の１００
ｍＡでの放電容量は１２４０ｍＡｈで、比較例２の電池
１よりも４４０ｍＡｈ放電容量が向上した。また、１Ａ
での放電容量は１０８０ｍＡｈあり、１Ａで比較すると
放電容量は７８０ｍＡｈも向上していることが分かっ
た。また、容量維持率は８７％にも達し、比較例２の電
池１に比べて４９％も向上した。これらの数値は、実施
例９の電池Ａに対しても、１００ｍＡで２１０ｍＡｈ，
１Ａで５１０ｍＡｈの放電容量の向上になっており、維
持率でも３２％の向上となっている。更に、実施例１０
の電池Ｂに対しても、１００ｍＡで１２０ｍＡｈ，１Ａ
で３４０ｍＡｈの放電容量の向上になっており、維持率
でも２１％の向上となっている。この様に、ＨＦＣＰを
用いれば電解液の導電率を高くすることができるため
に、この溶媒を９０容量％含む組成においても電池容量
の低下が少ない良好な電池が得られることが分かった。Example 11 Next, the electrolytic solution C prepared in Example 3 (that is, HFCP was 90% by volume,
Li in a solvent mixed with 10% by volume of ethylene carbonate
Battery C of Example 11 having the same specifications was prepared in the same manner using PF 6 (an electrolytic solution in which 0.1 mol / liter of PF 6 was dissolved), and the charge / discharge characteristics of the battery were evaluated. 100 of this battery
The discharge capacity at mA was 1240 mAh, which was higher than the battery 1 of Comparative Example 2 by 440 mAh. Also, 1A
, The discharge capacity was 1080 mAh, and compared with 1 A, it was found that the discharge capacity was improved by 780 mAh. In addition, the capacity retention ratio reached 87%, which was 49% higher than that of the battery 1 of Comparative Example 2. These values are 210 mAh at 100 mA for the battery A of Example 9, and
At 1A, the discharge capacity is improved by 510 mAh, and the maintenance rate is also improved by 32%. Further, Example 10
120 mAh at 100 mA, 1 A
In this case, the discharge capacity was improved by 340 mAh, and the maintenance ratio was also improved by 21%. As described above, since the conductivity of the electrolytic solution can be increased by using HFCP, it has been found that a good battery with a small decrease in battery capacity can be obtained even in a composition containing 90% by volume of this solvent.
【００２７】（実施例１２）次に、電解液としてＨＦＣ
Ｐの混合量を低減した実施例４で作製した電解液Ｄ（即
ち、ＨＦＣＰを７０容量％，エチレンカーボネートを３
０容量％混合した溶媒にＬｉＰＦ6を０.５モル／リッタ
ー溶解した電解液）を用いて、同じ仕様の実施例１２の
電池Ｄを、上記と同様の方法で作製し、電池の充放電特
性を評価した。この電池の１００ｍＡでの放電容量は１
２８０ｍＡｈで、比較例２の電池１よりも４８０ｍＡｈ
も放電容量が向上した。また、１Ａでの放電容量は１１
２０ｍＡｈあり、１Ａで比較すると放電容量は８２０ｍ
Ａｈも向上した。また、容量維持率は８８％であり、比
較例２の電池１に比べて５０％も向上している。これら
の数値は、実施例９の電池Ａに対しても、１００ｍＡで
２５０ｍＡｈ，１Ａで３００ｍＡｈの放電容量の向上に
なっており、維持率でも３３％もの向上となっている。
更に、実施例１０の電池Ｂに対しても、１００ｍＡで１
６０ｍＡｈ，１Ａで３８０ｍＡｈの放電容量の向上にな
っており、容量維持率でも２２％の向上となっている。
また、電池Ｃに対しても１００ｍＡで４０ｍＡｈ，１Ａ
で４０ｍＡｈの容量向上がある。Example 12 Next, HFC was used as the electrolyte.
The electrolyte solution D prepared in Example 4 in which the amount of P was reduced (ie, 70% by volume of HFCP and 3% of ethylene carbonate)
A battery D of Example 12 having the same specifications was prepared in the same manner as described above using an electrolyte solution in which 0.5 mol / liter of LiPF 6 was dissolved in a solvent in which 0% by volume was mixed, and the charge / discharge characteristics of the battery were obtained. Was evaluated. The discharge capacity at 100 mA of this battery was 1
280 mAh, which is 480 mAh higher than that of the battery 1 of Comparative Example 2.
The discharge capacity also improved. The discharge capacity at 1 A is 11
20mAh, discharge capacity is 820m when compared at 1A
Ah also improved. In addition, the capacity retention rate was 88%, which is 50% higher than that of the battery 1 of Comparative Example 2. These figures show that the discharge capacity of the battery A of Example 9 is improved by 250 mAh at 100 mA and 300 mAh at 1 A, and the maintenance rate is improved by 33%.
Further, for the battery B of Example 10, 1
The discharge capacity is improved by 380 mAh at 60 mAh and 1 A, and the capacity retention rate is also improved by 22%.
Also, for the battery C, 40 mAh at 100 mA, 1 A
And there is a capacity improvement of 40 mAh.
【００２８】（実施例１３）次に、電解液として実施例
５で作製した電解液Ｅ（即ち、ＨＦＣＰを５０容量％，
エチレンカーボネートを５０容量％混合した溶媒にＬｉ
ＰＦ6を１.０モル／リッター溶解した電解液）を用い
て、同じ仕様の実施例１３の電池Ｅを、上記と同様の方
法で作製し、電池の充放電特性を評価した。この電池の
１００ｍＡでの放電容量は１３２０ｍＡｈで、１Ａでの
放電容量は１２２０ｍＡｈと最も高い放電容量を示し
た。また、容量維持率は９２％にも達した。これは比較
例１の電池１と比べると、１００ｍＡで５２０ｍＡｈ，
１Ａで９２０ｍＡｈもの容量の向上になる。容量維持率
では、５４％の向上になっている。更に、電池Ｄと比べ
ても１００ｍＡで４０ｍＡｈ，１Ａで１００ｍＡｈもの
容量の向上になり、容量維持率では４％の向上になって
いる。Example 13 Next, the electrolytic solution E prepared in Example 5 (that is, HFCP was 50% by volume,
Li in a solvent mixed with 50% by volume of ethylene carbonate
Battery E of Example 13 having the same specifications was prepared in the same manner as described above using PF 6 (an electrolytic solution in which 1.0 mol / liter of PF 6 was dissolved), and the charge / discharge characteristics of the battery were evaluated. The discharge capacity at 100 mA of this battery was 1320 mAh, and the discharge capacity at 1 A was the highest discharge capacity of 1220 mAh. Further, the capacity retention ratio reached 92%. This is 520 mAh at 100 mA compared to the battery 1 of Comparative Example 1,
The capacity of 920 mAh at 1 A is improved. The capacity retention ratio is improved by 54%. Furthermore, compared to the battery D, the capacity is improved by 40 mAh at 100 mA, and 100 mAh at 1 A, and the capacity retention is improved by 4%.
【００２９】以上の様に、ＨＦＣＰは引火点の高い環状
カーボネートを広い範囲で相溶させることができるため
引火点のない範囲が広がり、ＨＦＣＰを５０容量％以上
含む２成分系の混合溶媒で高い導電率を実現することが
でき、上述した様に従来のフッ素化溶媒を用いた電池に
比べ、電池容量と負荷特性を飛躍的に改善することがで
きた。As described above, HFCP is capable of compatibilizing a wide range of cyclic carbonates having a high flash point, so that the range without a flash point is widened, and the HFCP is higher in a binary mixed solvent containing 50% by volume or more of HFCP. The conductivity was realized, and as described above, the battery capacity and load characteristics were significantly improved as compared with the battery using the conventional fluorinated solvent.
【００３０】（実施例１４）次に、電解液として実施例
６で作製した電解液Ｆ（即ち、ＨＦＣＰを７０容量％，
エチレンカーボネートを２７容量％，ジメチルカーボネ
ートを３容量％混合した溶媒にＬｉＰＦ6を０.５モル／
リッター溶解した電解液）を用いて、同じ仕様の実施例
１４の電池Ｆを、同様の方法で作製し、電池の充放電特
性を評価した。この電池の１００ｍＡでの放電容量は１
２９０ｍＡｈで、１Ａでの放電容量は１１５０ｍＡｈで
あった。これらの数値は、ＨＦＣＰを同一容量含む電解
液Ｄの電池Ｄに比べて、１００ｍＡで１０ｍＡｈ，１Ａ
で３０ｍＡｈの容量の向上になっており、維持率でも１
％の向上があった。ＨＦＣＰを７０容量％と多量に含む
組成の不燃性電解液に鎖状カーボネート溶媒を少量配合
することによって、電池容量及び負荷特性を更に改善す
ることができる。Example 14 Next, the electrolytic solution F prepared in Example 6 (that is, HFCP was 70% by volume,
LiPF 6 was added to a mixture of 27% by volume of ethylene carbonate and 3% by volume of dimethyl carbonate in an amount of 0.5 mol / L.
A battery F of Example 14 having the same specifications was prepared by the same method using the same electrolytic solution (liter dissolved), and the charge / discharge characteristics of the battery were evaluated. The discharge capacity at 100 mA of this battery was 1
At 290 mAh, the discharge capacity at 1 A was 1150 mAh. These values are 10 mAh and 1 A at 100 mA compared to the battery D of the electrolyte D containing the same volume of HFCP.
At 30 mAh, and the maintenance rate is 1
% Improvement. By blending a small amount of a chain carbonate solvent with a nonflammable electrolyte having a composition containing as much as 70% by volume of HFCP, the battery capacity and load characteristics can be further improved.
【００３１】（実施例１５）次に、電解液として実施例
７で作製した電解液Ｇ（即ち、ＨＦＣＰを７０容量％，
エチレンカーボネートを２５容量％，エチルメチルカー
ボネートを５容量％混合した溶媒にＬｉＰＦ6 を０.５
モル／リッター 溶解した電解液）を用いて、同じ仕様
の実施例１５の電池Ｇを、同様の方法で作製し、電池の
充放電特性を評価した。この電池の１００ｍＡでの放電
容量は１３００ｍＡｈで、１Ａでの放電容量は１１７０
ｍＡｈであった。また、容量維持率は９０％であった。
これらの値は、電池Ｆを更に１００ｍＡで１０ｍＡｈ，
１Ａで２０ｍＡｈ上回った。Example 15 Next, the electrolytic solution G prepared in Example 7 (that is, HFCP was 70% by volume,
LiPF 6 was added to a solvent in which 25% by volume of ethylene carbonate and 5% by volume of ethyl methyl carbonate were mixed.
A battery G of Example 15 having the same specifications was prepared in the same manner as described above, and the charge / discharge characteristics of the battery were evaluated. The discharge capacity at 100 mA of this battery was 1300 mAh, and the discharge capacity at 1 A was 1170.
mAh. The capacity retention was 90%.
These values indicate that the battery F is further charged at 10 mAh at 100 mA,
It exceeded 20 mAh at 1A.
【００３２】（実施例１６）次に、電解液として実施例
８で作製した電解液Ｈ（即ち、ＨＦＣＰを７０容量％，
エチレンカーボネートを２３容量％，ジエチルカーボネ
ートを７容量％混合した溶媒にＬｉＰＦ6を０.５モル／
リッター溶解した電解液）を用いて、同じ仕様の実施例
１６の電池Ｈを、同様の方法で作製し、電池の充放電特
性を評価した。この電池の１００ｍＡでの放電容量は１
３０５ｍＡｈで、１Ａでの放電容量は１１８０ｍＡｈで
あった。また、容量維持率は９０％であった。これらの
値は、電池Ｇを、更に、１００ｍＡで５ｍＡｈ，１Ａで
１０ｍＡｈ上回っている。Example 16 Next, the electrolytic solution H prepared in Example 8 (that is, HFCP was 70% by volume,
LiPF 6 was added to a solvent in which ethylene carbonate was mixed at 23% by volume and diethyl carbonate at 7% by volume with 0.5 mol / LiPF 6.
A battery H of Example 16 having the same specifications was prepared by the same method using the liter-dissolved electrolyte solution), and the charge / discharge characteristics of the battery were evaluated. The discharge capacity at 100 mA of this battery was 1
At 305 mAh, the discharge capacity at 1 A was 1180 mAh. The capacity retention was 90%. These values further exceed Battery G by 5 mAh at 100 mA and 10 mAh at 1 A.
【００３３】以上の様に、ＨＦＣＰを５０容量％以上、
引火点の高い環状カーボネートと混合することにより引
火点をなくし、導電率を向上した不燃性電解液を用いる
ことによって不燃性電解液を用いた電池の欠点であった
電池容量の低下と負荷特性の低下を改善することができ
た。また、鎖状カーボネートを不燃性の維持できる範囲
で少量混合することにより、これら不燃性電解液を用い
た電池の課題を更に改善することができる。As described above, 50% by volume or more of HFCP
The use of a non-flammable electrolyte with improved electrical conductivity eliminates the flash point by mixing with a cyclic carbonate having a high flash point. The drop could be improved. In addition, by mixing a small amount of the chain carbonate within a range in which nonflammability can be maintained, the problem of a battery using these nonflammable electrolytes can be further improved.
【００３４】[0034]
【発明の効果】以上、実施例により詳述した様に、本発
明の１，１，２，２，３，３，４−ヘプタフルオロシク
ロペンタンを含む電解液は、引火点のない不燃性の領域
で使用しても従来公開されているフッ素化溶媒に対して
リチウム塩を多量に溶解することができ、また、導電率
を向上できる。また、１，１，２，２，３，３，４−ヘ
プタフルオロシクロペンタンを含む電解液を用いること
により、引火点のない範囲の電解液であっても従来のフ
ッ素化溶媒を含む電解液に比べ電池容量が高く、且つ、
大電流での容量低下の少ない電池を得ることができる。
更に、ＨＦＰＣは引火点の高い環状カーボネートを広い
範囲で相溶でき、リチウム塩を溶解し、導電性を向上す
るための非フッ素化溶媒を多く含む組成においても引火
点をなくすことができるので、ＨＦＣＰを５０容量％以
上含む組成において良好な導電率の不燃性電解液を得る
ことができた。また、この電解液を用いることにより電
池容量及び負荷特性を大きく改善できる。As described above in detail, the electrolyte containing 1,1,2,2,3,3,4-heptafluorocyclopentane according to the present invention has a non-flammable property having no flash point. Even when used in the range, a large amount of a lithium salt can be dissolved in a conventionally disclosed fluorinated solvent, and the conductivity can be improved. In addition, by using an electrolyte containing 1,1,2,2,3,3,4-heptafluorocyclopentane, a conventional electrolyte containing a fluorinated solvent can be used even if the electrolyte has no flash point. Battery capacity is higher than
It is possible to obtain a battery with a small capacity reduction at a large current.
Furthermore, HFPC can dissolve a high-carbon carbonate having a high flash point in a wide range, dissolve a lithium salt, and eliminate a flash point even in a composition containing a large amount of a non-fluorinated solvent for improving conductivity. A non-flammable electrolyte having good conductivity was obtained in a composition containing HFCP of 50% by volume or more. Further, by using this electrolytic solution, the battery capacity and load characteristics can be greatly improved.
【図１】本発明の一実施例を示す試験電池の断面図であ
る。FIG. 1 is a cross-sectional view of a test battery showing one embodiment of the present invention.
１…負極集電体、２…負極活物質層、３…負極タブ端
子、４…正極集電体、５…正極活物質層、６…正極タブ
端子、７…セパレータ、８，１２…インシュレーター、
９…負極缶、１０…ガスケット、１１…正極蓋。DESCRIPTION OF SYMBOLS 1 ... Negative electrode current collector, 2 ... Negative electrode active material layer, 3 ... Negative electrode tab terminal, 4 ... Positive electrode current collector, 5 ... Positive electrode active material layer, 6 ... Positive electrode tab terminal, 7 ... Separator, 8, 12 ... Insulator,
9: negative electrode can, 10: gasket, 11: positive electrode lid.
Claims (4)
おいて、前記非水溶媒は化１ 【化１】 に示す構造の１，１，２，２，３，３，４−ヘプタフル
オロシクロペンタンを含むことを特徴とする非水電解
液。In a non-aqueous electrolytic solution obtained by dissolving an electrolyte in a non-aqueous solvent, the non-aqueous solvent is represented by the following formula: A non-aqueous electrolytic solution comprising 1,1,2,2,3,3,4-heptafluorocyclopentane having the structure shown in (1).
３，４−ヘプタフルオロシクロペンタンを５０容量％以
上含むことを特徴とする請求項１記載の非水電解液。2. The non-aqueous solvent comprises 1,1,2,2,3,
2. The non-aqueous electrolyte according to claim 1, wherein the non-aqueous electrolyte contains 3,4-heptafluorocyclopentane in an amount of 50% by volume or more.
ムを吸蔵放出可能な正極と、非水電解液とを備えたリチ
ウム２次電池において、前記非水電解液が１，１，２，
２，３，３，４−ヘプタフルオロシクロペンタンを含む
ことを特徴とするリチウム２次電池。3. A lithium secondary battery comprising a negative electrode capable of inserting and extracting lithium, a positive electrode capable of inserting and extracting lithium, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is 1,1,2,2.
A lithium secondary battery comprising 2,3,3,4-heptafluorocyclopentane.
３，４−ヘプタフルオロシクロペンタンを５０容量％以
上含むことを特徴とする請求項３記載のリチウム２次電
池。4. The method according to claim 1, wherein the non-aqueous electrolyte is 1,1,2,2,3,
4. The lithium secondary battery according to claim 3, wherein the lithium secondary battery contains 3,4-heptafluorocyclopentane in an amount of 50% by volume or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15748999A JP3721857B2 (en) | 1999-06-04 | 1999-06-04 | Nonflammable electrolyte and lithium secondary battery using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15748999A JP3721857B2 (en) | 1999-06-04 | 1999-06-04 | Nonflammable electrolyte and lithium secondary battery using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000348762A true JP2000348762A (en) | 2000-12-15 |
| JP3721857B2 JP3721857B2 (en) | 2005-11-30 |
Family
ID=15650813
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15748999A Expired - Fee Related JP3721857B2 (en) | 1999-06-04 | 1999-06-04 | Nonflammable electrolyte and lithium secondary battery using the same |
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| Country | Link |
|---|---|
| JP (1) | JP3721857B2 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007234339A (en) * | 2006-02-28 | 2007-09-13 | Three M Innovative Properties Co | Solvent composition and electrochemical device |
| US7341807B2 (en) | 2003-08-26 | 2008-03-11 | Japan Aerospace Exploration Agency | Non-flammable nonaqueous electrolyte solution and lithium ion cell using same |
| US7998615B2 (en) | 2004-01-15 | 2011-08-16 | Panasonic Corporation | Nonaqueous electrolyte for electrochemical devices |
| US8211577B2 (en) | 2008-05-19 | 2012-07-03 | Panasonic Corporation | Nonaqueous solvent and nonaqueous electrolytic solution for electricity storage device and nonaqueous electricity storage device, lithium secondary battery and electric double layer capacitor using the same |
| US8247118B2 (en) | 2008-10-21 | 2012-08-21 | Panasonic Corporation | Non-aqueous solvent and non-aqueous electrolytic solution for energy storage device, and energy storage device, lithium secondary battery and electric double-layer capacitor each comprising the non-aqueous solvent or the non-aqueous electrolytic solution |
| EP2642581A4 (en) * | 2010-11-16 | 2015-10-28 | Panasonic Ip Man Co Ltd | Nonaqueous solvent for electricity storage device |
| CN113181589A (en) * | 2021-03-22 | 2021-07-30 | 华中科技大学 | High-efficiency fire extinguishing agent and fire safety extinguishing process |
| WO2023190273A1 (en) * | 2022-03-30 | 2023-10-05 | 日本ゼオン株式会社 | Nonaqueous electrolytic solution and electrochemical device |
-
1999
- 1999-06-04 JP JP15748999A patent/JP3721857B2/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7341807B2 (en) | 2003-08-26 | 2008-03-11 | Japan Aerospace Exploration Agency | Non-flammable nonaqueous electrolyte solution and lithium ion cell using same |
| US7998615B2 (en) | 2004-01-15 | 2011-08-16 | Panasonic Corporation | Nonaqueous electrolyte for electrochemical devices |
| JP2007234339A (en) * | 2006-02-28 | 2007-09-13 | Three M Innovative Properties Co | Solvent composition and electrochemical device |
| US8211577B2 (en) | 2008-05-19 | 2012-07-03 | Panasonic Corporation | Nonaqueous solvent and nonaqueous electrolytic solution for electricity storage device and nonaqueous electricity storage device, lithium secondary battery and electric double layer capacitor using the same |
| US8247118B2 (en) | 2008-10-21 | 2012-08-21 | Panasonic Corporation | Non-aqueous solvent and non-aqueous electrolytic solution for energy storage device, and energy storage device, lithium secondary battery and electric double-layer capacitor each comprising the non-aqueous solvent or the non-aqueous electrolytic solution |
| EP2642581A4 (en) * | 2010-11-16 | 2015-10-28 | Panasonic Ip Man Co Ltd | Nonaqueous solvent for electricity storage device |
| CN113181589A (en) * | 2021-03-22 | 2021-07-30 | 华中科技大学 | High-efficiency fire extinguishing agent and fire safety extinguishing process |
| WO2023190273A1 (en) * | 2022-03-30 | 2023-10-05 | 日本ゼオン株式会社 | Nonaqueous electrolytic solution and electrochemical device |
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| Publication number | Publication date |
|---|---|
| JP3721857B2 (en) | 2005-11-30 |
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