JP2002175834A - Lithium secondary battery - Google Patents
Lithium secondary batteryInfo
- Publication number
- JP2002175834A JP2002175834A JP2000374645A JP2000374645A JP2002175834A JP 2002175834 A JP2002175834 A JP 2002175834A JP 2000374645 A JP2000374645 A JP 2000374645A JP 2000374645 A JP2000374645 A JP 2000374645A JP 2002175834 A JP2002175834 A JP 2002175834A
- Authority
- JP
- Japan
- Prior art keywords
- lithium
- electrolyte
- secondary battery
- battery
- lithium secondary
- 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]
【産業上の利用分野】本発明は、非水電解液を有するリ
チウム二次電池電池に関し、より詳しくは非水電解液の
改良に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery having a non-aqueous electrolyte, and more particularly to an improvement in a non-aqueous electrolyte.
【０００２】[0002]
【従来の技術】近年、エネルギー密度が高いことから携
帯機器を中心にリチウム二次電池が注目されている。こ
の電池は、水の分解電圧よりも高い電圧を有しているた
め、非水系電解液が用いられている。2. Description of the Related Art In recent years, lithium secondary batteries have attracted attention mainly for portable devices due to their high energy density. Since this battery has a voltage higher than the decomposition voltage of water, a non-aqueous electrolyte is used.
【０００３】非水電解液の溶質としてはＬｉＰＦ6 とＬ
ｉＢＦ4 などが使用されているが、なかでもＬｉＰＦ6
を溶質とする電解液は、イオン伝導度が高いため、最も
多く用いられている。As a solute of a non-aqueous electrolyte, LiPF 6 and L
iBF 4 and the like are used, among which LiPF 6
The solute is most often used because of its high ionic conductivity.
【０００４】しかしながら、ＬｉＰＦ6 を電解質に使用
した場合、充電状態で６０℃の高温で保存を行うと、電
池の内部抵抗が大幅に増加するという問題がある。電池
の内部抵抗の増加は、放電容量の減少を招き、結果とし
てエネルギ密度が著しく低下してしまう。この問題は特
開平８−６４２３７号公報に開示されているように、電
解質に用いるリチウム塩にＬｉＰＦ6 とＬｉＢＦ4 とを
混合して用いることで解決することができる。However, when LiPF 6 is used as the electrolyte, there is a problem that when the battery is stored at a high temperature of 60 ° C. in a charged state, the internal resistance of the battery is greatly increased. An increase in the internal resistance of the battery causes a decrease in the discharge capacity, and as a result, the energy density is significantly reduced. This problem can be solved by mixing LiPF 6 and LiBF 4 with a lithium salt used for an electrolyte, as disclosed in Japanese Patent Application Laid-Open No. 8-64237.
【０００５】しかし、単にＬｉＰＦ6 とＬｉＢＦ4 とを
混合しただけでは、６０℃保存後のサイクル特性が非常
に悪くなる場合があり、さらなる改良が必要であった。[0005] However, simply mixing LiPF 6 and LiBF 4 may extremely deteriorate the cycle characteristics after storage at 60 ° C., and further improvement is required.
【０００６】[0006]
【発明が解決しようとする課題】本発明の目的は、高い
イオン伝導度を有し、内部抵抗の増加を抑えつつ、サイ
クル特性の良好なリチウム二次電池を提供することであ
る。SUMMARY OF THE INVENTION It is an object of the present invention to provide a lithium secondary battery having high ionic conductivity and excellent cycle characteristics while suppressing an increase in internal resistance.
【０００７】[0007]
【課題を解決するための手段】すなわち上記目的は、以
下の本発明の構成により解決する。 （１） リチウムを吸蔵／放出する正極と負極と、リチ
ウム塩を溶解した電解液とを有し、リチウム塩としてフ
ッ化燐酸リチウムとフッ化硼素酸リチウムとを有し、電
解液溶媒として３０体積％超のエチレンカーボネートを
含有するリチウム二次電池。 （２） 前記フッ化燐酸リチウムとフッ化硼素酸リチウ
ムとをＬｉＰＦ6 とＬｉＢＦ4 とに換算してモル比で９
／１〜７／３有する（１）のリチウム二次電池。That is, the above object is solved by the following constitution of the present invention. (1) A positive electrode that absorbs / releases lithium, a negative electrode, and an electrolytic solution in which a lithium salt is dissolved, lithium lithium phosphate and lithium fluoroborate as lithium salts, and 30 vol. Lithium secondary battery containing more than 3% ethylene carbonate. (2) The molar ratio of the lithium fluorophosphate and lithium fluoroborate converted to LiPF 6 and LiBF 4 is 9
/ 1 to 7/3, the lithium secondary battery of (1).
【０００８】[0008]
【作用】高いイオン伝導度を有し、内部抵抗の増加を抑
えつつ、サイクル特性の良好な二次電池を得るには、電
解液中の電解質塩のみならず、電解液の組成が重要であ
る。In order to obtain a secondary battery having high ionic conductivity and good cycle characteristics while suppressing an increase in internal resistance, not only the electrolyte salt in the electrolyte but also the composition of the electrolyte is important. .
【０００９】本発明者らは、電解液中のエチレンカーボ
ネート量が重要な要素となることを見いだし、本発明に
至った。The present inventors have found that the amount of ethylene carbonate in the electrolyte is an important factor, and have reached the present invention.
【００１０】すなわち、好ましくはフッ化燐酸リチウム
とフッ化硼素酸リチウムとをＬｉＰＦ6 とＬｉＢＦ4 と
に換算してモル比で９／１〜７／３混合したものを電解
質として使用することで、６０℃の高温保存での電池の
内部抵抗の増加を大幅に減少することができる。しかし
ながら、電解液溶媒に体積％で３０％を超えるエチレン
カーボネートを含有していない場合、保存後のサイクル
特性が大幅に劣化する。これは、初回充電時に負極に生
成される皮膜や６０℃保存時に生成した皮膜の安定度に
起因すると考えられ、フッ化燐酸リチウムとフッ化硼素
酸リチウムを混合したものを電解質として使用し、か
つ、電解液溶媒に３０体積％超のエチレンカーボネート
を含有したものを使用することで、電極上に生成する皮
膜が安定化すると考えられる。その結果、６０℃保存時
の電池の内部抵抗の増加を抑制でき、保存後も良好なサ
イクル特性を得られると考えられる。That is, preferably, a mixture of lithium fluorophosphate and lithium fluoroborate converted to LiPF 6 and LiBF 4 at a molar ratio of 9/1 to 7/3 is used as an electrolyte. The increase in the internal resistance of the battery during storage at a high temperature of 60 ° C. can be greatly reduced. However, when the electrolyte solvent does not contain more than 30% by volume of ethylene carbonate, the cycle characteristics after storage are significantly deteriorated. This is considered to be due to the stability of the film formed on the negative electrode at the time of the first charge and the film formed at the time of storage at 60 ° C., and a mixture of lithium fluorophosphate and lithium fluoroborate was used as the electrolyte, and It is considered that the use of the electrolyte solvent containing more than 30% by volume of ethylene carbonate stabilizes the film formed on the electrode. As a result, it is considered that an increase in the internal resistance of the battery during storage at 60 ° C. can be suppressed, and good cycle characteristics can be obtained even after storage.
【００１１】[0011]
【発明の実施の形態】本発明の二次電池は、リチウムを
吸蔵／放出する正極と負極と、リチウム塩を溶解した電
解液とを有し、リチウム塩としてフッ化燐酸リチウムと
フッ化硼素酸リチウムとを有し、電解液溶媒として３０
体積％超のエチレンカーボネートを含有するものであ
る。BEST MODE FOR CARRYING OUT THE INVENTION A secondary battery according to the present invention has a positive electrode for absorbing / desorbing lithium, a negative electrode, and an electrolytic solution in which a lithium salt is dissolved. As the lithium salt, lithium fluoride phosphate and boron fluoride are used. And lithium, and 30 as an electrolyte solvent.
It contains more than% by volume of ethylene carbonate.
【００１２】また、好ましくはフッ化燐酸リチウムとフ
ッ化硼素酸リチウムとをＬｉＰＦ6とＬｉＢＦ4 とに換
算してモル比で９／１〜７／３有する。It is preferable that lithium fluoride phosphate and lithium fluoroborate have a molar ratio of 9/1 to 7/3 in terms of LiPF 6 and LiBF 4 .
【００１３】このように、電解質塩としてフッ化燐酸リ
チウムとフッ化硼素酸リチウムとを用いることで、Ｌｉ
ＰＦ6 並の高い電気伝導度を維持しつつ、内部抵抗の増
加を抑えることができる。そして、この電解液の溶媒に
少なくとも３０体積％超のエチレンカーボネートを含有
させることにより、高温保存時のサイクル特性を良好に
することができる。As described above, by using lithium fluorophosphate and lithium fluoroborate as electrolyte salts, Li
While maintaining the PF 6 parallel high electric conductivity, it is possible to suppress an increase in internal resistance. By including at least 30% by volume of ethylene carbonate in the solvent of the electrolytic solution, the cycle characteristics during high-temperature storage can be improved.
【００１４】本発明では、好ましくはフッ化燐酸リチウ
ムとフッ化硼素酸リチウムとをＬｉＰＦ6 とＬｉＢＦ4
とに換算してモル比で９／１〜７／３、より好ましくは
８．５／１．５〜７．５／２．５有する。この範囲より
もフッ化硼素酸リチウムの割合が増加すると、６０℃保
存前の電池の内部抵抗が大きくなり、放電容量が減少し
てしまう。また、上記範囲よりフッ化燐酸リチウムの割
合が増加すると、高温保存後の内部抵抗が増加してく
る。In the present invention, preferably, lithium fluoride phosphate and lithium fluoride borate are combined with LiPF 6 and LiBF 4
And the molar ratio is 9/1 to 7/3, more preferably 8.5 / 1.5 to 7.5 / 2.5. If the proportion of lithium fluoroborate is higher than this range, the internal resistance of the battery before storage at 60 ° C. increases, and the discharge capacity decreases. When the proportion of lithium fluorophosphate increases from the above range, the internal resistance after high-temperature storage increases.
【００１５】エチレンカーボネートは、電解液溶媒の３
０体積％超含有されていればよく、好ましくは３０体積
％超、５０体積％未満、特に３３体積％以上、５０体積
％未満である。エチレンカーボネートの割合が上記範囲
より増えると、粘度が上昇し、レート特性が悪化してく
る。[0015] Ethylene carbonate is used as an electrolyte solvent.
It is sufficient if the content is more than 0% by volume, and preferably more than 30% by volume and less than 50% by volume, particularly 33% by volume or more and less than 50% by volume. When the proportion of ethylene carbonate is higher than the above range, the viscosity increases and the rate characteristics deteriorate.
【００１６】エチレンカーボネート（略称ＥＣ）以外の
電解液溶媒としては、電解質塩との相溶性が良好なもの
であれば特に制限はされないが、リチウム電池等では高
い動作電圧でも分解の起こらない極性有機溶媒が好まし
い。例えば、プロピレンカーボネート（略称ＰＣ）、ブ
チレンカーボネート、ジメチルカーボネート（略称ＤＭ
Ｃ）、ジエチルカーボネート、エチルメチルカーボネー
ト等のカーボネート類、テトラヒドロフラン（略称ＴＨ
Ｆ）、２−メチルテトラヒドロフラン等の環式エーテ
ル、１，３−ジオキソラン、４−メチルジオキソラン等
の環式エーテル、γ−ブチロラクトン等のラクトン、ス
ルホラン等を挙げることができる。The electrolyte solvent other than ethylene carbonate (abbreviated as EC) is not particularly limited as long as it has good compatibility with the electrolyte salt. However, in a lithium battery or the like, a polar organic solvent which does not decompose even at a high operating voltage. Solvents are preferred. For example, propylene carbonate (abbreviation PC), butylene carbonate, dimethyl carbonate (abbreviation DM)
C), carbonates such as diethyl carbonate and ethyl methyl carbonate, tetrahydrofuran (abbreviated as TH
F), cyclic ethers such as 2-methyltetrahydrofuran, cyclic ethers such as 1,3-dioxolane and 4-methyldioxolane, lactones such as γ-butyrolactone, and sulfolane.
【００１７】エチレンカーボネートとこれらの１種また
は２種以上を混合して電解液溶媒として用いることがで
きる。Ethylene carbonate and one or more of these can be mixed and used as an electrolyte solvent.
【００１８】電解液中のリチウム塩の濃度は０．５〜２
モル／リットルが好ましく、より好ましくは０．８〜
１．５モル／リットルである。リチウム塩の濃度がこの
範囲より高いと電解液の粘度が高くなり、ハイレートで
の放電容量や低温での放電容量が抵下し、低いとリチウ
ムイオンの供給が間に合わなくなり、ハイレートでの放
電容量や低温での放電容量が低下する。The concentration of the lithium salt in the electrolyte is 0.5 to 2
Mol / liter is preferred, and more preferably 0.8 to
1.5 mol / l. If the concentration of the lithium salt is higher than this range, the viscosity of the electrolytic solution becomes higher, and the discharge capacity at a high rate or the discharge capacity at a low temperature is reduced. The discharge capacity at low temperatures decreases.
【００１９】リチウム二次電池の構造は特に限定されな
いが、通常、正極、負極及びセパレータから構成され、
積層型電池や円筒型電池等に適用される。このような正
極、セパレータ、負極をこの順に積層し、圧着して電池
素体とする。Although the structure of the lithium secondary battery is not particularly limited, it is usually composed of a positive electrode, a negative electrode and a separator,
It is applied to a stacked battery, a cylindrical battery, and the like. Such a positive electrode, a separator, and a negative electrode are laminated in this order, and pressed to form a battery body.
【００２０】電極は、好ましくは電極活物質と結着剤、
必要により導電助剤との組成物を用いる。The electrode preferably comprises an electrode active material and a binder,
If necessary, a composition with a conductive additive is used.
【００２１】負極には、炭素材料、リチウム金属、リチ
ウム合金あるいは酸化物材料のような負極活物質を用
い、正極には、リチウムイオンがインターカレート・デ
インターカレート可能な酸化物または炭素材料のような
正極活物質を用いることが好ましい。このような電極を
用いることにより、良好な特性のリチウム二次電池を得
ることができる。For the negative electrode, a negative electrode active material such as a carbon material, lithium metal, lithium alloy or oxide material is used. For the positive electrode, an oxide or carbon material capable of intercalating / deintercalating lithium ions is used. It is preferable to use such a positive electrode active material as described above. By using such an electrode, a lithium secondary battery having excellent characteristics can be obtained.
【００２２】電極活物質として用いる炭素材料は、例え
ば、メソカーボンマイクロビーズ（ＭＣＭＢ）、天然あ
るいは人造の黒鉛、樹脂焼成炭素材料、カーボンブラッ
ク、炭素繊維などから適宜選択すればよい。これらは粉
末として用いられる。中でも黒鉛が好ましく、その平均
粒子径は１〜３０μm 、特に５〜２５μm であることが
好ましい。平均粒子径が小さすぎると、充放電サイクル
寿命が短くなり、また、容量のばらつき（個体差）が大
きくなる傾向にある。平均粒子径が大きすぎると、容量
のばらつきが著しく大きくなり、平均容量が小さくなっ
てしまう。平均粒子径が大きい場合に容量のばらつきが
生じるのは、黒鉛と集電体との接触や黒鉛同士の接触に
ばらつきが生じるためと考えられる。The carbon material used as the electrode active material may be appropriately selected from, for example, mesocarbon microbeads (MCMB), natural or artificial graphite, resin fired carbon material, carbon black, carbon fiber and the like. These are used as powders. Above all, graphite is preferred, and its average particle size is preferably 1 to 30 μm, particularly preferably 5 to 25 μm. If the average particle size is too small, the charge / discharge cycle life tends to be short and the variation in capacity (individual difference) tends to be large. If the average particle size is too large, the dispersion of the capacity becomes extremely large, and the average capacity becomes small. It is considered that the capacity variation occurs when the average particle size is large because the contact between the graphite and the current collector and the contact between the graphites vary.
【００２３】リチウムイオンがインターカレート・デイ
ンターカレート可能な酸化物としては、リチウムを含む
複合酸化物が好ましく、例えば、ＬｉＣｏＯ2、ＬｉＭ
ｎ2Ｏ 4、ＬｉＮｉＯ2、ＬｉＶ2Ｏ4などが挙げられる。
これらの酸化物の粉末の平均粒子径は１〜４０μm 程度
であることが好ましい。Lithium ion is intercalated day
Intercalatable oxides include lithium
Complex oxides are preferred, for example, LiCoOTwo, LiM
nTwoO Four, LiNiOTwo, LiVTwoOFourAnd the like.
The average particle size of these oxide powders is about 1 to 40 μm.
It is preferred that
【００２４】電極には、必要により導電助剤が添加され
る。導電助剤としては、好ましくは黒鉛、カーボンブラ
ック、炭素繊維、ニッケル、アルミニウム、銅、銀等の
金属が挙げられ、特に黒鉛、カーボンブラックが好まし
い。If necessary, a conductive additive is added to the electrode. Preferred examples of the conductive auxiliary agent include metals such as graphite, carbon black, carbon fiber, nickel, aluminum, copper, and silver. Particularly, graphite and carbon black are preferable.
【００２５】電極組成は正極では、重量比で活物質：導
電助剤：結着剤＝８０〜９４：２〜８：２〜１８の範囲
が好ましく、負極では、重量比で活物質：導電助剤：結
着剤＝７０〜９７：０〜２５：３〜１０の範囲が好まし
い。The electrode composition is preferably in the range of 80 to 94: 2 to 8: 2 to 18 in terms of the weight ratio of the active material: the conductive auxiliary agent: the binder in the positive electrode. Agent: Binder = 70-97: 0-25: 3-10 is preferred.
【００２６】電極の製造は、まず、活物質と結着剤、必
要に応じて導電助剤を、結着剤溶液に分散し、塗布液を
調製する。In manufacturing an electrode, first, an active material, a binder, and, if necessary, a conductive auxiliary are dispersed in a binder solution to prepare a coating solution.
【００２７】そして、この電極塗布液を集電体に塗布す
る。塗布する手段は特に限定されず、集電体の材質や形
状などに応じて適宜決定すればよい。一般に、メタルマ
スク印刷法、静電塗装法、ディップコート法、スプレー
コート法、ロールコート法、ドクターブレード法、グラ
ビアコート法、スクリーン印刷法等が使用されている。
その後、必要に応じて、平板プレス、カレンダーロール
等により圧延処理を行う。Then, the electrode coating solution is applied to a current collector. The means for applying is not particularly limited, and may be determined as appropriate according to the material and shape of the current collector. Generally, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method, and the like are used.
Thereafter, if necessary, a rolling treatment is performed by a flat plate press, a calender roll, or the like.
【００２８】集電体は、電池の使用するデバイスの形状
やケース内への集電体の配置方法などに応じて、適宜通
常の集電体から選択すればよい。一般に、正極にはアル
ミニウム等が、負極には銅、ニッケル等が使用される。
なお、集電体は、通常、金属箔、金属メッシュなどが使
用される。金属箔よりも金属メッシュの方が電極との接
触抵抗が小さくなるが、金属箔でも十分小さな接触抵抗
が得られる。The current collector may be appropriately selected from ordinary current collectors according to the shape of the device used by the battery, the method of arranging the current collector in the case, and the like. Generally, aluminum or the like is used for the positive electrode, and copper, nickel, or the like is used for the negative electrode.
Note that a metal foil, a metal mesh, or the like is generally used as the current collector. Although the metal mesh has lower contact resistance with the electrode than the metal foil, a sufficiently low contact resistance can be obtained even with the metal foil.
【００２９】そして、溶媒を蒸発させ、電極を作製す
る。塗布厚は、５０〜４００μm 程度とすることが好ま
しい。Then, the solvent is evaporated to produce an electrode. The coating thickness is preferably about 50 to 400 μm.
【００３０】セパレータに含浸させる電解液は一般に電
解質塩と溶媒よりなる。電解質塩、溶媒は、上記で示し
たものを用いる。The electrolyte for impregnating the separator generally comprises an electrolyte salt and a solvent. As the electrolyte salt and the solvent, those described above are used.
【００３１】セパレータを形成する固体電解質ないしセ
パレータシートは、ポリフッ化ビニリデンホモポリマ
ー、特に乳化重合法により製造されたものを用いること
が好ましい。As the solid electrolyte or separator sheet forming the separator, it is preferable to use a polyvinylidene fluoride homopolymer, particularly one produced by an emulsion polymerization method.
【００３２】本発明で使用される固体電解質用微多孔膜
は、以下に示す湿式相分離法により形成することが好ま
しい。The microporous membrane for a solid electrolyte used in the present invention is preferably formed by the following wet phase separation method.
【００３３】湿式相分離法とは、溶液流延法による成膜
において、相分離を溶液中で行う方法である。すなわ
ち、微多孔膜となるポリマーをこのポリマーが溶解しう
る溶媒に溶解させ、得られた成膜原液を金属あるいはプ
ラスチックフィルム等の支持体上に均一に塗布して膜を
形成する。その後、膜状にキャストした成膜原液を凝固
浴と呼ばれる溶液中に導入し,相分離を生じさせること
で微多孔膜を得る方法である。成膜原液の塗布は、凝固
浴中で行ってもよい。The wet phase separation method is a method of performing phase separation in a solution in film formation by a solution casting method. That is, a polymer to be a microporous film is dissolved in a solvent in which the polymer can be dissolved, and the obtained film-forming stock solution is uniformly applied on a support such as a metal or plastic film to form a film. Thereafter, a film-forming stock solution cast into a film is introduced into a solution called a coagulation bath to cause phase separation to obtain a microporous film. The application of the film forming stock solution may be performed in a coagulation bath.
【００３４】上記微多孔膜と電極との接着性を向上させ
るための接着剤を使用してもよい。具体的には、ユニス
トール（三井化学社製）、ＳＢＲ（日本ゼオン社製）、
アクアテックス（中央理化社製）、アドコート（モート
ン社製）等のポリオレフィン系接着剤等を挙げることが
でき、なかでもアクアテックス等が好ましい。An adhesive for improving the adhesiveness between the microporous membrane and the electrode may be used. Specifically, Unistor (manufactured by Mitsui Chemicals, Inc.), SBR (manufactured by Zeon Corporation),
Examples thereof include polyolefin-based adhesives such as Aquatex (manufactured by Chuo Rika Co., Ltd.) and Adcoat (manufactured by Morton), and among them, Aquatex is preferred.
【００３５】接着剤は、水、あるいはトルエン等の有機
溶剤に溶解、あるいは分散させて、散布、塗布等により
微多孔膜に付着・配置される。The adhesive is dissolved or dispersed in water or an organic solvent such as toluene and adhered and arranged on the microporous film by spraying, coating or the like.
【００３６】微多孔膜の空孔率は５０％以上、好ましく
は５０〜９０％、より好ましくは７０〜８０％である。
また、孔径は０．０２μm 以上、２μm 以下、好ましく
は０．０２μm 以上、１μm 以下、より好ましくは０．
０４μm 以上、０．８μm 以下、特に好ましくは０．１
μm 以上、０．８μm 以下、さらに好ましくは０．１μ
m 以上、０．６μm 以下である。微多孔膜の膜厚は、好
ましくは２０〜８０μm 、より好ましくは２５〜４５μ
m である。The porosity of the microporous membrane is 50% or more, preferably 50 to 90%, more preferably 70 to 80%.
Further, the pore diameter is 0.02 μm or more and 2 μm or less, preferably 0.02 μm or more and 1 μm or less, more preferably 0.1 μm or less.
0.4 μm or more and 0.8 μm or less, particularly preferably 0.1 μm or less.
μm or more, 0.8 μm or less, more preferably 0.1 μm
m or more and 0.6 μm or less. The thickness of the microporous membrane is preferably 20 to 80 μm, more preferably 25 to 45 μm.
m.
【００３７】微多孔膜は、融点が好ましくは１５０℃以
上、特に１６０〜１７０℃、融解熱が好ましくは３０J
／g以上、特に４０〜６０J／gの材料により形成されて
いることが好ましい。The microporous membrane has a melting point of preferably 150 ° C. or more, particularly 160 to 170 ° C., and a heat of fusion of preferably 30 J.
/ G or more, particularly preferably 40 to 60 J / g.
【００３８】セパレータには他のゲル型高分子を用いて
もよい。例えば、（１）ポリエチレンオキサイド、ポリ
プロピレンオキサイド等のポリアルキレンオキサイド、
（２）エチレンオキサイドとアクリレートの共重合体、
（３）エチレンオキサイドとグリシルエーテルの共重合
体、（４）エチレンオキサイドとグリシルエーテルとア
リルグリシルエーテルとの共重合体、（５）ポリアクリ
レート（６）ポリアクリロニトリル（７）ポリフッ化ビ
ニリデン、フッ化ビニリデン−ヘキサフルオロプロピレ
ン共重合体、フッ化ビニリデン−塩化３フッ化エチレン
共重合体、フッ化ビニリデン−ヘキサフルオロプロビレ
ンフッ素ゴム、フッ化ビニリデン“テトラフルオロエチ
レン−ヘキサフルオロプロピレンフッ素ゴム等のフッ素
系高分子等が挙げられる。Other gel-type polymers may be used for the separator. For example, (1) polyalkylene oxide such as polyethylene oxide and polypropylene oxide;
(2) a copolymer of ethylene oxide and acrylate,
(3) a copolymer of ethylene oxide and glycyl ether, (4) a copolymer of ethylene oxide, glycyl ether and allyl glycyl ether, (5) polyacrylate (6) polyacrylonitrile (7) polyvinylidene fluoride, fluoride Fluorinated materials such as vinylidene-hexafluoropropylene copolymer, vinylidene fluoride-ethylene chloride trifluoride copolymer, vinylidene fluoride-hexafluoropropylene fluororubber, vinylidene fluoride "tetrafluoroethylene-hexafluoropropylene fluororubber, etc. Polymers and the like.
【００３９】ゲル高分子は電解液と混ぜてもよく、また
セパレータに塗布をしてもよい。さらに、開始剤を入れ
ることにより、紫外線、ＥＢ、熱等でゲル高分子を架橋
させてもよい。The gel polymer may be mixed with the electrolytic solution, or may be applied to the separator. Further, by adding an initiator, the gel polymer may be cross-linked by ultraviolet rays, EB, heat or the like.
【００４０】固体状電解質の膜厚は、５〜１００μm 、
さらには５〜６０μm 、特に１０〜４０μm であること
が好ましい。本発明の固体状電解質は強度が強いので、
膜厚を薄くすることができる。本発明の固体状電解質
は、実用上６０μm 以下にはできなかった従来のゲル電
解質と比べて薄膜化が可能であり、さらには、溶液系の
リチウムイオン電池において使用されているセパレータ
（通常２５μm ）よりも薄くできる。そのため、固体状
電解質を用いる利点の一つである薄型大面積化、すなわ
ちシート状形態化が可能である。The thickness of the solid electrolyte is 5 to 100 μm,
Further, the thickness is preferably 5 to 60 μm, particularly preferably 10 to 40 μm. Since the solid electrolyte of the present invention has high strength,
The film thickness can be reduced. The solid electrolyte of the present invention can be made thinner than a conventional gel electrolyte which could not be practically reduced to 60 μm or less, and furthermore, a separator (usually 25 μm) used in a solution type lithium ion battery. Can be thinner than Therefore, it is possible to form a thin and large area, that is, a sheet form, which is one of the advantages of using a solid electrolyte.
【００４１】そのほかのセパレータ構成材料として、ポ
リエチレン、ポリプロピレンなどのポリオレフイン類の
一種又は二種以上（二種以上の場合、二層以上のフィル
ムの張り合わせ物などがある）、ポリエチレンテレフタ
ーレートのようなポリエステル類、エチレン−テトラフ
ルオロエチレン共重合体のような熱可塑性フッ素樹脂
類、セルロース類などがある。シートの形態はJIS−P81
17に規定する方法で測定した通気度が５〜２０００秒／
１００cc程度、厚さが５〜１００μm 程度の微多孔膜フ
ィルム、織布、不織布などがある。Other constituent materials of the separator include one or more of polyolefins such as polyethylene and polypropylene (in the case of two or more, there are laminated films of two or more layers), such as polyethylene terephthalate. Examples include polyesters, thermoplastic fluororesins such as ethylene-tetrafluoroethylene copolymer, and celluloses. Sheet form is JIS-P81
The air permeability measured by the method specified in 17 is 5 to 2000 seconds /
There is a microporous membrane film, woven fabric, nonwoven fabric, etc. having a thickness of about 100 cc and a thickness of about 5 to 100 μm.
【００４２】外装袋は、例えばアルミニウム等の金属層
の両面に、熱接着性樹脂層としてのポリプロピレン、ポ
リエチレン等のポリオレフィン樹脂層や耐熱性のポリエ
ステル樹脂層が積層されたラミネートフィルムから構成
されている。外装袋は、予め２枚のラミネートフィルム
をそれらの３辺の端面の熱接着性樹脂層相互を熱接着し
て第１のシール部を形成し、１辺が開口した袋状に形成
される。あるいは、一枚のラミネートフィルムを折り返
して両辺の端面を熱接着してシール部を形成して袋状と
してもよい。The outer bag is composed of a laminated film in which a polyolefin resin layer such as polypropylene or polyethylene or a heat-resistant polyester resin layer as a heat-adhesive resin layer is laminated on both surfaces of a metal layer such as aluminum. . The outer bag is formed in a bag shape with one side opened by previously bonding two laminated films to each other by thermally bonding the heat-adhesive resin layers on the three end surfaces thereof to each other. Alternatively, a single laminated film may be folded back and the both end faces may be thermally bonded to form a seal portion to form a bag.
【００４３】ラミネートフィルムとしては、ラミネート
フィルムを構成する金属箔と導出端子間の絶縁を確保す
るため、内装側から熱接着性樹脂層／ポリエステル樹脂
層／金属箔／ポリエステル樹脂層の積層構造を有するラ
ミネートフィルムを用いることが好ましい。このような
ラミネートフィルムを用いることにより、熱接着時に高
融点のポリエステル樹脂層が溶けずに残るため、導出端
子と外装袋の金属箔との離間距離を確保し、絶縁を確保
することができる。そのため、ラミネートフィルムのポ
リエステル樹脂層の厚さは、５〜１００μm 程度とする
ことが好ましい。The laminated film has a laminated structure of a heat-adhesive resin layer / polyester resin layer / metal foil / polyester resin layer from the interior side in order to ensure insulation between the metal foil constituting the laminated film and the lead terminals. It is preferable to use a laminate film. By using such a laminated film, the high melting point polyester resin layer remains without melting at the time of thermal bonding, so that a separation distance between the lead terminal and the metal foil of the outer package can be ensured, and insulation can be ensured. Therefore, the thickness of the polyester resin layer of the laminate film is preferably about 5 to 100 μm.
【００４４】[0044]
【実施例】＜実施例1＞正極活物質としてＬｉＣｏＯ2
を９０重量部、導電剤として炭素粉末を６重量部、結着
剤としてPVDF（ポリフッ化ビニリデン）を４重量部、こ
れらをN−メチルピロリドン（NMP）溶液と混合して、ス
ラリーを調整し、このスラリーをアルミニウム箔上にド
クタープレード法で塗布、加圧ロールを通すことで正極
を作製した。Example 1 Example 1 LiCoO 2 as a positive electrode active material
90 parts by weight, 6 parts by weight of carbon powder as a conductive agent, 4 parts by weight of PVDF (polyvinylidene fluoride) as a binder, and mixing these with an N-methylpyrrolidone (NMP) solution to prepare a slurry, This slurry was applied on an aluminum foil by a doctor blade method and passed through a pressure roll to produce a positive electrode.
【００４５】負極活物質としてMCMB（メソフェーズカー
ボンマイクロビーズ）を８７重量部、導電剤として炭素
粉末を３重量部、結着剤としてPVDFを１０重量部、これ
らをNMP溶液と混合することでスラリーを調整し、この
スラリーを銅箔上にドクタープレード法にて塗布、加圧
ロールを通すことで負極を作製した。87 parts by weight of MCMB (mesophase carbon microbeads) as a negative electrode active material, 3 parts by weight of carbon powder as a conductive agent, 10 parts by weight of PVDF as a binder, and a slurry by mixing these with an NMP solution. The slurry was adjusted, and the slurry was applied on a copper foil by a doctor blade method and passed through a pressure roll to produce a negative electrode.
【００４６】これら電極の中央に約直径２mmの大きさで
エチレン−メタアクリル酸の共重合体を点付けし、正
極、セパレーター、負極、セパレーター、正極、・・・
と１００℃で樹脂を溶融しながら、繰り返し積層し、積
層体を得た。セパレーターには、ＰＶＤＦの多孔質膜を
使用した。An ethylene-methacrylic acid copolymer having a diameter of about 2 mm was spotted at the center of these electrodes to form a positive electrode, a separator, a negative electrode, a separator, a positive electrode,.
The resin was repeatedly laminated while melting the resin at 100 ° C. to obtain a laminate. A PVDF porous membrane was used for the separator.
【００４７】得られた積層体に電流取り出し用のリード
を付け、所定の電解液、一定量とともにこれらをアルミ
ラミネートパックに封入、真空シールを行い、その後８
０℃で熱プレスを行いパック内の積層体を一体化し、電
池を作成した。A lead for current extraction was attached to the obtained laminate, and a predetermined amount of electrolyte and a predetermined amount thereof were sealed in an aluminum laminate pack, and vacuum sealing was performed.
A hot press was performed at 0 ° C. to integrate the laminated body in the pack, thereby producing a battery.
【００４８】得られた電池を数回充放電を行った後、
４．２Vまで充電し、６０℃で一週間保存した。種々の
電解液ごとの１Ｃ放電容量、６０℃、１週間高温保存前
と後の電池の１kHzでの内部抵抗の値とその変化率およ
び、保存後４サイクル後の容量保持率（保存後４サイク
ル日の放電容量／保存後１サイクル日の放電容量×１０
０）を表１に示す。After charging and discharging the obtained battery several times,
The battery was charged to 4.2 V and stored at 60 ° C. for one week. 1C discharge capacity for various electrolytes, internal resistance at 1 kHz before and after high-temperature storage at 60 ° C for 1 week and its rate of change, and capacity retention after 4 cycles after storage (4 cycles after storage) Discharge capacity per day / discharge capacity for one cycle after storage × 10
0) is shown in Table 1.
【００４９】[0049]
【表１】 [Table 1]
【００５０】表１から明らかなように、ＬｉＰＦ6 とＬ
ｉＢＦ4 を混合して用いることで６０℃保存時の電池の
内部抵抗の増大を抑制することが可能だが、電解液溶媒
中にエチレンカーボネートが３０体積％超含有していな
いと、保存後のサイクル特性が劣化してしまうことがわ
かる。As is clear from Table 1, LiPF 6 and L
It is possible to suppress the increase in the internal resistance of the battery during storage at 60 ° C. by using iBF 4 as a mixture. However, if the electrolyte solvent does not contain more than 30% by volume of ethylene carbonate, the cycle after storage is reduced. It can be seen that the characteristics are deteriorated.
【００５１】＜実施例２＞負極活物質をMCF（メソフェ
ーズカーボンファイバー）、およぴBMCF（ホウ素を添加
したMCFとし、実施例１と同様に電池を作製し、同様に
６０℃保存試験を行った。種々の電解液ごとの１Ｃ放電
容量、６０℃、１週間高温保存前と後の電池の１kHzで
の内部抵抗の値とその変化率および、保存後４サイクル
後の容量保持率（保存後４サイクル日の放電容量／保存
後１サイクル日の放電容量×１００）を表２に示す。Example 2 A battery was manufactured in the same manner as in Example 1, and a 60 ° C. storage test was performed in the same manner as in Example 1 except that the negative electrode active material was MCF (mesophase carbon fiber) and BMCF (MCF to which boron was added). The 1C discharge capacity of each electrolyte, the internal resistance at 1 kHz and its rate of change before and after high-temperature storage at 60 ° C. for 1 week, and the capacity retention after 4 cycles of storage (after storage) Table 2 shows the discharge capacity on the 4th cycle / discharge capacity on the 1st cycle after storage × 100).
【００５２】[0052]
【表２】 [Table 2]
【００５３】表２から明らかなように、負極活物質に関
わらず、実施例1と同様な効果が得られることがわか
る。As is evident from Table 2, the same effects as in Example 1 can be obtained regardless of the negative electrode active material.
【００５４】[0054]
【発明の効果】以上のように本発明によれば、高いイオ
ン伝導度を有し、内部抵抗の増加を抑えつつ、サイクル
特性の良好なリチウム二次電池を提供することができ
る。As described above, according to the present invention, it is possible to provide a lithium secondary battery having high ionic conductivity and excellent cycle characteristics while suppressing an increase in internal resistance.
Claims (2)
と、リチウム塩を溶解した電解液とを有し、 リチウム塩としてフッ化燐酸リチウムとフッ化硼素酸リ
チウムとを有し、 電解液溶媒として３０体積％超のエチレンカーボネート
を含有するリチウム二次電池。1. A battery comprising: a positive electrode for absorbing / releasing lithium; a negative electrode; and an electrolyte in which a lithium salt is dissolved; lithium lithium phosphate and lithium fluoroborate as lithium salts; A lithium secondary battery containing more than 30% by volume of ethylene carbonate.
リチウムとをＬｉＰＦ6 とＬｉＢＦ4 とに換算してモル
比で９／１〜７／３有する請求項１のリチウム二次電
池。2. The lithium secondary battery according to claim 1, wherein said lithium fluoride phosphate and lithium fluoride borate have a molar ratio of 9/1 to 7/3 in terms of LiPF 6 and LiBF 4 .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000374645A JP5217066B2 (en) | 2000-12-08 | 2000-12-08 | Lithium secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000374645A JP5217066B2 (en) | 2000-12-08 | 2000-12-08 | Lithium secondary battery |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2012249553A Division JP5516700B2 (en) | 2012-11-13 | 2012-11-13 | Lithium secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2002175834A true JP2002175834A (en) | 2002-06-21 |
| JP5217066B2 JP5217066B2 (en) | 2013-06-19 |
Family
ID=18843795
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000374645A Expired - Lifetime JP5217066B2 (en) | 2000-12-08 | 2000-12-08 | Lithium secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP5217066B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004077599A1 (en) * | 2003-02-27 | 2004-09-10 | Mitsubishi Chemical Corporation | Nonaqueous electrolytic solution and lithium secondary battery |
| JP2006164527A (en) * | 2004-12-02 | 2006-06-22 | Matsushita Electric Ind Co Ltd | Flat type nonaqueous electrolytic solution battery |
| US7083878B2 (en) | 2003-02-27 | 2006-08-01 | Mitsubishi Chemical Corporation | Nonaqueous electrolytic solution and lithium secondary battery |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0864237A (en) * | 1994-08-25 | 1996-03-08 | Sanyo Electric Co Ltd | Nonaqueous electrolyte battery |
| JPH08339824A (en) * | 1995-06-09 | 1996-12-24 | Toshiba Corp | Nonaqueous electrolyte secondary battery |
| JPH11135107A (en) * | 1997-10-28 | 1999-05-21 | Toshiba Corp | Lithium secondary battery |
| JP2000331715A (en) * | 1999-05-18 | 2000-11-30 | Asahi Chem Ind Co Ltd | Nonaqueous secondary battery |
-
2000
- 2000-12-08 JP JP2000374645A patent/JP5217066B2/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0864237A (en) * | 1994-08-25 | 1996-03-08 | Sanyo Electric Co Ltd | Nonaqueous electrolyte battery |
| JPH08339824A (en) * | 1995-06-09 | 1996-12-24 | Toshiba Corp | Nonaqueous electrolyte secondary battery |
| JPH11135107A (en) * | 1997-10-28 | 1999-05-21 | Toshiba Corp | Lithium secondary battery |
| JP2000331715A (en) * | 1999-05-18 | 2000-11-30 | Asahi Chem Ind Co Ltd | Nonaqueous secondary battery |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004077599A1 (en) * | 2003-02-27 | 2004-09-10 | Mitsubishi Chemical Corporation | Nonaqueous electrolytic solution and lithium secondary battery |
| US7083878B2 (en) | 2003-02-27 | 2006-08-01 | Mitsubishi Chemical Corporation | Nonaqueous electrolytic solution and lithium secondary battery |
| JP2006164527A (en) * | 2004-12-02 | 2006-06-22 | Matsushita Electric Ind Co Ltd | Flat type nonaqueous electrolytic solution battery |
Also Published As
| Publication number | Publication date |
|---|---|
| JP5217066B2 (en) | 2013-06-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4431304B2 (en) | Lithium ion secondary battery separator and lithium ion secondary battery provided with the same | |
| US11245107B2 (en) | Positive electrode mixture for secondary battery, method for manufacturing positive electrode for secondary battery, and method for manufacturing secondary battery | |
| JP4517440B2 (en) | Lithium ion solid electrolyte secondary battery | |
| JP2018198131A (en) | Lithium ion secondary battery | |
| JP2015069957A (en) | Separator for lithium ion secondary battery and method for manufacturing the same, and lithium ion secondary battery and method for manufacturing the same | |
| JP2008097879A (en) | Lithium ion secondary battery | |
| JP2015072805A (en) | Nonaqueous secondary battery | |
| JP2015125948A (en) | Lithium ion secondary battery | |
| KR20190128140A (en) | Manufacturing method of secondary battery | |
| JP2018147769A (en) | Separator for electrochemical element and nonaqueous electrolyte battery | |
| JP4561041B2 (en) | Lithium secondary battery | |
| JP2009032408A (en) | Secondary battery separator | |
| JP4453667B2 (en) | Lithium ion secondary battery | |
| JP7088969B2 (en) | Lithium ion separator for secondary batteries and lithium ion secondary batteries | |
| JP4180335B2 (en) | Non-aqueous electrolyte battery | |
| JPH11260414A (en) | Nonaqueous system secondary battery | |
| JP5516700B2 (en) | Lithium secondary battery | |
| JP5217066B2 (en) | Lithium secondary battery | |
| WO2017110842A1 (en) | Nonaqueous secondary battery and method for manufacturing same | |
| KR20030005254A (en) | A multi-layered polymer electrolyte and lithium secondary battery comprising the same | |
| JP2003257496A (en) | Lithium secondary battery | |
| JP5239109B2 (en) | Lithium ion secondary battery | |
| JP2003297337A (en) | Electrode structure, its manufacturing method, and secondary battery | |
| JP2006179205A (en) | Nonaqueous electrolytic solution battery | |
| WO2015037522A1 (en) | Nonaqueous secondary battery |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| RD01 | Notification of change of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7421 Effective date: 20040601 |
|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20071026 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20100707 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20100713 |
|
| A601 | Written request for extension of time |
Free format text: JAPANESE INTERMEDIATE CODE: A601 Effective date: 20100907 |
|
| A602 | Written permission of extension of time |
Free format text: JAPANESE INTERMEDIATE CODE: A602 Effective date: 20100910 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20101012 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20110920 |
|
| A601 | Written request for extension of time |
Free format text: JAPANESE INTERMEDIATE CODE: A601 Effective date: 20111118 |
|
| A602 | Written permission of extension of time |
Free format text: JAPANESE INTERMEDIATE CODE: A602 Effective date: 20111124 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20111216 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20120814 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20121113 |
|
| A911 | Transfer to examiner for re-examination before appeal (zenchi) |
Free format text: JAPANESE INTERMEDIATE CODE: A911 Effective date: 20121203 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20130205 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20130218 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20160315 Year of fee payment: 3 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 Ref document number: 5217066 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| EXPY | Cancellation because of completion of term |