JP2000021445A - Nonaqueous electrolyte secondary battery - Google Patents
Nonaqueous electrolyte secondary batteryInfo
- Publication number
- JP2000021445A JP2000021445A JP10186549A JP18654998A JP2000021445A JP 2000021445 A JP2000021445 A JP 2000021445A JP 10186549 A JP10186549 A JP 10186549A JP 18654998 A JP18654998 A JP 18654998A JP 2000021445 A JP2000021445 A JP 2000021445A
- Authority
- JP
- Japan
- Prior art keywords
- secondary battery
- lithium
- positive electrode
- aqueous electrolyte
- electrolyte
- 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.)
- Pending
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、非水電解液二次電
池に関する。TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte secondary battery.
【０００２】[0002]
【従来の技術】最近、各種のホータブルな電気・電子機
器の多様化、小型化、軽量化の進展に伴い、その駆動源
として用いられる二次電池に対しても多様化、小型化、
軽量化が要望されている。2. Description of the Related Art In recent years, with the diversification, miniaturization, and weight reduction of various kinds of electric and electronic devices, secondary batteries used as their driving sources have been diversified and miniaturized.
Lightening is demanded.
【０００３】前記二次電池としては、従来より作動電圧
が１．５Ｖ級のニッケルカドミウム二次電池が知られて
いる。しかしながら、ニッケルカドミウム二次電池は電
解液が水溶液であるため、使用環境の温度によって十分
な電流を取り出せないという問題があった。例えば、使
用環境が０℃より低くなると、電解液の凍結等が生じて
電流を取り出すことが殆ど不可能になる。また、長期安
定性も劣る。As the secondary battery, a nickel cadmium secondary battery having an operating voltage of 1.5 V class has been known. However, the nickel cadmium secondary battery has a problem that a sufficient current cannot be taken out depending on the temperature of the use environment since the electrolyte is an aqueous solution. For example, when the use environment is lower than 0 ° C., the electrolyte solution freezes and the like, and it is almost impossible to extract a current. In addition, long-term stability is poor.
【０００４】これに対し、有機溶媒を含む非水電解液を
用いる非水電解液二次電池の研究、開発が最近、盛んに
行なわれており、リチウム二次電池として実用化されて
いる。この非水電解液二次電池は、一般に高エネルギー
密度を有し、かつ貯蔵・保管時における自己放電も少な
く、さらに環境温度が−２０〜６０℃という広い範囲で
電流を取り出すことができる利点を有する。On the other hand, research and development of a non-aqueous electrolyte secondary battery using a non-aqueous electrolyte containing an organic solvent have been actively conducted recently, and have been put to practical use as lithium secondary batteries. This non-aqueous electrolyte secondary battery has the advantage that it generally has a high energy density, has little self-discharge during storage and storage, and can take out current in a wide range of environmental temperatures of -20 to 60 ° C. Have.
【０００５】しかしながら、前記非水電解液二次電池は
電解液が水溶液である二次電池に比べて単位面積当たり
の充電電流の最大値が小さいという問題があった。これ
は、駆動源としての二次電池の小型化が要望されている
現状において、水溶液系の二次電池に比べて不利にな
る。[0005] However, the non-aqueous electrolyte secondary battery has a problem that the maximum value of the charging current per unit area is smaller than that of a secondary battery in which the electrolyte is an aqueous solution. This is disadvantageous in comparison with an aqueous solution type secondary battery in the current situation in which a secondary battery as a driving source is required to be downsized.
【０００６】具体的には、二次電池がコイン型である場
合、電池反応に寄与する反応面積は非常に小さくなるた
め、微小電流しか流すことができないことになる。仮
に、大電流で充電を行なうと活物質の利用率の低下や充
放電サイクル寿命特性の劣化をを招く。Specifically, when the secondary battery is a coin type, the reaction area contributing to the battery reaction becomes very small, so that only a small current can flow. If charging is performed with a large current, a reduction in the utilization rate of the active material and a deterioration in the charge / discharge cycle life characteristics are caused.
【０００７】前記非水電解液二次電池の代表的なものと
しては、リチウム二次電池が知られている。このリチウ
ム二次電池の正極活物質としては、例えば五酸化バナジ
ウムやマンガン酸化物のようにその結晶構造内にリチウ
ムイオンを直接かつ可逆的に出入りできる材料や、リチ
ウムコバルト酸化物、リチウムニッケル酸化物、リチウ
ムマンガン酸化物のように充放電に関与するリチウム源
がリチウムイオンとして配位結合した状態のスピネル型
結晶構造の材料等が検討され、その一部が実用化されて
いる。As a typical non-aqueous electrolyte secondary battery, a lithium secondary battery is known. As the positive electrode active material of this lithium secondary battery, for example, a material such as vanadium pentoxide or manganese oxide capable of directly and reversibly entering and exiting lithium ions in its crystal structure, lithium cobalt oxide, lithium nickel oxide A material having a spinel-type crystal structure in which a lithium source involved in charge and discharge, such as lithium manganese oxide, is coordinated and bonded as lithium ions has been studied, and some of them have been put to practical use.
【０００８】しかしながら、前述した正極材料はいずれ
もリチウムの標準単極電位（以後、Ｌｉ+ ／Ｌｉ電位と
称す）を基準にして３．０〜４．０Ｖ前後の放電電位を
示すため、これらの材料を用いたリチウム二次電池はそ
の作動電位が１．５Ｖにならず、前述したニッケルカド
ミウム二次電池と互換することが困難である。However, all of the above-mentioned positive electrode materials exhibit a discharge potential of about 3.0 to 4.0 V with respect to a standard monopolar potential of lithium (hereinafter referred to as Li + / Li potential). The operating potential of the lithium secondary battery using the material does not reach 1.5 V, and it is difficult to be compatible with the above-mentioned nickel cadmium secondary battery.
【０００９】ところで、スピネル型結晶構造を有する材
料のうち、Ｌｉx Ｔｉy Ｏ4 で示される材料の放電電位
はＬｉ+ ／Ｌｉ電位に対して１．５Ｖ付近にあることが
知られている。特に、ｘ＝４／３，ｙ＝５／３の材料、
つまりＬｉ4/3 Ｔｉ5/3 Ｏ4の放電電位はＬｉ+ ／Ｌｉ
電位を基準にして１．５Ｖを示すことが知られている。
このようなＬｉ4/3 Ｔｉ5/3 Ｏ4 材料は、充放電を１０
０サイクル以上繰り返しても、９５％以上の放電維持率
を示す。また、Ｌｉ+ ／Ｌｉ電位に対して３．０Ｖ以上
の電位を印加する過充電状態にあっても、その結晶構造
の変化が起こらない特性を有する。このため、前記材料
は長寿命のリチウム二次電池の電池材料として期待され
ている。It is known that among materials having a spinel-type crystal structure, the discharge potential of a material represented by Li x Ti y O 4 is around 1.5 V with respect to the Li + / Li potential. In particular, a material of x = 4/3, y = 5/3,
That is, the discharge potential of Li 4/3 Ti 5/3 O 4 is Li + / Li
It is known to show 1.5 V with reference to the potential.
Such a Li 4/3 Ti 5/3 O 4 material has a charge and discharge of 10
Even if it is repeated for 0 cycles or more, it shows a discharge maintenance rate of 95% or more. Further, even in an overcharged state in which a potential of 3.0 V or more with respect to the Li + / Li potential is applied, the crystal structure does not change. For this reason, the material is expected as a battery material for a long-life lithium secondary battery.
【００１０】このようなことから、Ｌｉx Ｔｉy Ｏ4 を
用いたリチウム二次電池が提案されている。例えば、特
開平６−２７５２６３号公報にはＬｉ+ ／Ｌｉ電位に対
して２．０Ｖ以上の放電電位を示す正極および負極に前
記Ｌｉx Ｔｉy Ｏ4 を用いたリチウム二次電池が開示さ
れている。また、特開平７−３２０７８４号公報にはＬ
ｉ2 ＭｎＯ3 やＬｉＭｎＯ2 を正極材料として用い、Ｌ
ｉ4/3 Ｔｉ5/3 Ｏ4 またはＬｉＴｉ2 Ｏ4 を負極材料と
して用いることが開示されている。[0010] Under such circumstances, a lithium secondary battery using Li x Ti y O 4 has been proposed. For example, JP-A-6-275263 discloses a lithium secondary battery using the Li x Ti y O 4 as a positive electrode and a negative electrode exhibiting a discharge potential of 2.0 V or more with respect to Li + / Li potential. I have. Also, JP-A-7-320784 discloses L
Using i2 MnO3 or LiMnO2 as the cathode material,
It is disclosed that i 4/3 Ti 5/3 O 4 or LiTi 2 O 4 is used as a negative electrode material.
【００１１】しかしながら、前述した公開公報に開示さ
れた発明はＬｉx Ｔｉy Ｏ4 をいずれも負極材料として
用いており、しかも正極活物質の特性が電池性能を強く
規制するため、Ｌｉx Ｔｉy Ｏ4 が持つ充放電サイクル
寿命、過充電特性、充放電時の電位変化の平坦性等の優
れた特性を十分に生かせないという問題があった。[0011] However, none of the invention Li x Ti y O 4, which is disclosed in publications described above is used as a negative electrode material, and since the characteristics of the positive electrode active material is strongly regulate the battery performance, Li x Ti y There is a problem that the excellent characteristics of O 4 such as charge / discharge cycle life, overcharge characteristics, and flatness of potential change during charge / discharge cannot be fully utilized.
【００１２】なお、Ｌｉx Ｔｉy Ｏ4 を正極に用いたリ
チウム二次電池の場合には、理論的に前記Ｌｉx Ｔｉy
Ｏ4 の働きによって優れた過充電特性を発揮できること
が期待されているものの、未だ実用化されていない。こ
れは、次のような理由によるものと考えられる。Incidentally, in the case of a lithium secondary battery using Li x Ti y O 4 as a positive electrode, theoretically, the Li x Ti y
Although it is expected that excellent overcharge characteristics can be exhibited by the action of O 4 , it has not yet been put to practical use. This is considered to be due to the following reasons.
【００１３】例えば、負極としてリチウム箔を用いた場
合、充放電の繰り返しによりリチウム箔が微細化した
り、リチウム箔の表面にリチウムの樹枝状突起が成長し
てそれがセパレータを突き破って正極と接触して内分短
絡を発生したり、電池の充放電サイクル特性の劣化を招
き、電池寿命を短くする。For example, when a lithium foil is used as a negative electrode, the lithium foil becomes finer due to repetition of charge and discharge, or dendrites of lithium grow on the surface of the lithium foil and break through the separator to come into contact with the positive electrode. As a result, the internal short circuit may occur or the charge / discharge cycle characteristics of the battery may be deteriorated, thereby shortening the battery life.
【００１４】このような問題に対してＬｉ−Ａｌ合金を
負極に用いることが知られている。しかしながら、Ｌｉ
−Ａｌ合金の放電電位はＬｉ+ ／Ｌｉ電位を基準にして
約０．４Ｖであるため、結局そのリチウム二次電池の作
動電圧は１．１Ｖ（１．５Ｖ−０．４Ｖ）程度になって
しまい、１．５Ｖ系電池として不適切になる。It is known that a Li-Al alloy is used for the negative electrode to solve such a problem. However, Li
Since the discharge potential of the Al alloy is about 0.4 V with reference to the Li + / Li potential, the operating voltage of the lithium secondary battery eventually becomes about 1.1 V (1.5 V-0.4 V). This makes the battery unsuitable as a 1.5 V battery.
【００１５】一方、リチウム二次電池に用いられる非水
電解液の溶媒としては一般にエチレンカーボネート、プ
ロピレンカーボネート等の非プロトン性有機溶媒が使用
されている。また、前記非水電解液の電解質としてはテ
トラフルオロホウ酸リチウム、過塩素酸リチウム、ヘキ
サフルオロリン酸リチウム等が使用されている。しかし
ながら、このような組成の非水電解液を有するリチウム
二次電池においては充電時等において前記非水電解液が
電極に吸蔵されたリチウムと反応し、いわゆる自己放電
を生じて充放電効率が低下したり、サイクル特性が悪化
したりする等の問題があった。On the other hand, as a solvent of a non-aqueous electrolyte used in a lithium secondary battery, an aprotic organic solvent such as ethylene carbonate or propylene carbonate is generally used. As the electrolyte of the non-aqueous electrolyte, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluorophosphate, or the like is used. However, in a lithium secondary battery having a nonaqueous electrolyte having such a composition, the nonaqueous electrolyte reacts with lithium occluded in the electrode at the time of charging or the like, causing a so-called self-discharge and a reduction in charge / discharge efficiency. And the cycle characteristics are deteriorated.
【００１６】[0016]
【発明が解決しようとする課題】本発明は、充電時にお
ける非水電解液と電極の反応による自己放電の発生を抑
制し、かつ優れた充放電効率やサイクル特性を有する
１．５Ｖの作動が可能な非水電解液二次電池を提供しよ
うとするものである。DISCLOSURE OF THE INVENTION The present invention is intended to suppress the occurrence of self-discharge due to the reaction between a non-aqueous electrolyte and an electrode during charging and to operate at 1.5 V having excellent charge / discharge efficiency and cycle characteristics. An object of the present invention is to provide a possible non-aqueous electrolyte secondary battery.
【００１７】[0017]
【課題を解決するための手段】本発明に係わる非水電解
液二次電池は、Ｌｉ4/3 Ｔｉ5/3 Ｏ4 を活物質として含
む正極と、リチウムイオンの吸蔵・放出が可能に炭素材
料を含む負極と、エチレンカーボネートを含む２成分以
上の混合溶媒に電解質としてのリチウムフルオロメタン
スルホン酸イミドを溶解した非水電解液とを具備したこ
とを特徴するものである。A non-aqueous electrolyte secondary battery according to the present invention comprises a positive electrode containing Li 4/3 Ti 5/3 O 4 as an active material, and a carbon material capable of absorbing and releasing lithium ions. It is characterized by comprising a negative electrode containing a material, and a non-aqueous electrolytic solution in which lithium fluoromethanesulfonic acid imide as an electrolyte is dissolved in a mixed solvent of two or more components containing ethylene carbonate.
【００１８】前記非水電解液中の混合溶媒は、エチレン
カーボネートが１０〜９０体積％の割合で含有されるこ
とが好ましい。The mixed solvent in the non-aqueous electrolyte preferably contains ethylene carbonate at a ratio of 10 to 90% by volume.
【００１９】[0019]
【発明の実施の形態】以下、本発明に係わる非水電解液
二次電池を図１を参照して詳細に説明する。例えばステ
ンレス鋼製の正極缶１内には、正極２が収納されてい
る。この正極２が接する前記正極缶１の内面には、コロ
イダルカーボンのような集電体３が被覆されている。セ
パレータ４は、前記正極２上に配置されている。前記セ
パレータ４には、非水電解液が含浸保持されている。負
極５は、前記セパレータ４上に配置されている。前記正
極缶１の開口部には、絶縁ガスケット６を介して負極缶
７が設けられており、この負極缶７および前記正極缶１
のかしめ加工により前記正極缶１および前記負極缶７内
に前記正極２、セパレ―タ４および負極５が密閉されて
いる。なお、前記負極５が接する前記負極缶７の内面は
エキスパンドメタルような集電体８が配置されている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a non-aqueous electrolyte secondary battery according to the present invention will be described in detail with reference to FIG. For example, a positive electrode 2 is housed in a positive electrode can 1 made of stainless steel. A current collector 3 such as colloidal carbon is coated on the inner surface of the positive electrode can 1 in contact with the positive electrode 2. The separator 4 is disposed on the positive electrode 2. The separator 4 is impregnated with a non-aqueous electrolyte. The negative electrode 5 is disposed on the separator 4. At the opening of the positive electrode can 1, a negative electrode can 7 is provided via an insulating gasket 6, and the negative electrode can 7 and the positive electrode can 1 are provided.
The positive electrode 2, the separator 4 and the negative electrode 5 are hermetically sealed in the positive electrode can 1 and the negative electrode can 7 by caulking. Note that a current collector 8 such as an expanded metal is disposed on the inner surface of the negative electrode can 7 in contact with the negative electrode 5.
【００２０】次に、前記正極２、負極５およびセパレー
タ４および非水電解液について詳細に説明する。Next, the positive electrode 2, the negative electrode 5, the separator 4, and the non-aqueous electrolyte will be described in detail.
【００２１】（１）正極２ この正極２は、Ｌｉ4/3 Ｔｉ5/3 Ｏ4 からなる活物質
と、黒鉛のような導電助剤と、ポリテトラフルオロエチ
レンのような結着剤とを含む混合物を加圧成形すること
により作製される。(1) Positive Electrode 2 This positive electrode 2 comprises an active material composed of Li 4/3 Ti 5/3 O 4 , a conductive additive such as graphite, and a binder such as polytetrafluoroethylene. It is produced by press-molding the mixture containing.
【００２２】前記正極活物質と、導電助剤と、結着剤と
の混合割合は、１０２：９：４〜９８：１１：６にする
ことが好ましい。It is preferable that the mixing ratio of the positive electrode active material, the conductive additive, and the binder is 102: 9: 4 to 98: 11: 6.
【００２３】（２）負極４ この負極５は、リチウムを吸蔵・放出する炭素質材料、
導電剤および結着剤からなる混合物を加圧成形すること
により作製される。(2) Negative electrode 4 This negative electrode 5 is a carbonaceous material that absorbs and releases lithium.
It is produced by press-molding a mixture comprising a conductive agent and a binder.
【００２４】前記炭素質材料としては、例えば人造黒
鉛、天然黒鉛、熱分解炭素、コークス、樹脂焼成体、メ
ソフェーズ小球体、メソフェーズ系ピッチ等を用いるこ
とができる。As the carbonaceous material, for example, artificial graphite, natural graphite, pyrolytic carbon, coke, resin fired body, mesophase small sphere, mesophase pitch and the like can be used.
【００２５】前記導電材としては、例えばアセチレンブ
ラック、カーボンブラック等を用いることができる。As the conductive material, for example, acetylene black, carbon black or the like can be used.
【００２６】前記結着剤としては、例えばスチレン・ブ
タジエンラテックス（ＳＢＲ）、カルボキシメチルセル
ロース（ＣＭＣ）、ポリテトラフルオロエチレン（ＰＴ
ＦＥ）、ポリフッ化ビニリデン（ＰＶＤＥ）、エチレン
−プロピレン−ジエン共重合体（ＥＰＤＭ）、ニトリル
−ブタジエンゴム（ＮＢＲ）、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−ヘ
キサフルオロプロピレン−テトラフルオロエチレン３元
系共重合体、ポリトリフルオロエチレン（ＰＴｒＦ
Ｅ）、フッ化ビニリデン−トリフルオロエチレン共重合
体、フッ化ビニリデン−テトラフルオロエチレン共重合
体等を用いることができる。Examples of the binder include styrene-butadiene latex (SBR), carboxymethylcellulose (CMC), and polytetrafluoroethylene (PT
FE), polyvinylidene fluoride (PVDE), ethylene-propylene-diene copolymer (EPDM), nitrile-butadiene rubber (NBR), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetra Fluoroethylene terpolymer, polytrifluoroethylene (PTrF
E), a vinylidene fluoride-trifluoroethylene copolymer, a vinylidene fluoride-tetrafluoroethylene copolymer, or the like can be used.
【００２７】（３）セパレータ４ このセパレータ４は、例えばポリプロピレン不織布、微
孔性ポリエチレンフィルム等からなる。(3) Separator 4 The separator 4 is made of, for example, a polypropylene nonwoven fabric, a microporous polyethylene film, or the like.
【００２８】（４）非水電解液 この非水電解液は、エチレンカーボネートを含む２成分
以上の混合溶媒に電解質としてのリチウムフルオロメタ
ンスルホン酸イミド［ＬｉＮ（ＣＦ3 ＳＯ2 ）2 ］を溶
解した組成を有する。(4) Nonaqueous Electrolyte In this nonaqueous electrolyte, lithium fluoromethanesulfonic acid imide [LiN (CF 3 SO 2 ) 2 ] as an electrolyte was dissolved in a mixed solvent of two or more components including ethylene carbonate. Having a composition.
【００２９】前記エチレンカーボネートに混合される他
の溶媒としては、例えばプロピレンカーボネート（Ｐ
Ｃ）、ブチレンカーボネート（ＢＣ）、ジメチルカーボ
ネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、
エチルメチルカーボネート（ＥＭＣ）、γ−ブチロラク
トン（γ−ＢＬ）、スルホラン、アセトニトリル、１，
２−ジメトキシエタン、１，３−ジメトキシプロパン、
ジメチルエーテル、テトラヒドロフラン（ＴＨＦ）、２
−メチルテトラヒドロフラン等を挙げることができる。
特に、他の溶媒としてはγ−ブチロラクトンが好まし
い。As the other solvent to be mixed with the ethylene carbonate, for example, propylene carbonate (P
C), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC),
Ethyl methyl carbonate (EMC), γ-butyrolactone (γ-BL), sulfolane, acetonitrile, 1,
2-dimethoxyethane, 1,3-dimethoxypropane,
Dimethyl ether, tetrahydrofuran (THF), 2
-Methyltetrahydrofuran and the like.
In particular, γ-butyrolactone is preferred as another solvent.
【００３０】前記エチレンカーボネートは、混合溶媒中
に１０〜９０体積％配合することにより充放電効率をよ
り向上することが可能になる。The charge and discharge efficiency can be further improved by adding 10 to 90% by volume of the ethylene carbonate to the mixed solvent.
【００３１】前記電解質であるリチウムフルオロメタン
スルホン酸イミドは、前記混合溶媒に対して０．５〜
１．５モル／Ｌ溶解するることが望ましい。The electrolyte, lithium fluoromethanesulfonimide, is used in an amount of 0.5 to 0.5 with respect to the mixed solvent.
It is desirable to dissolve at 1.5 mol / L.
【００３２】以上説明した本発明に係わる非水電解液二
次電池は、Ｌｉ4/3 Ｔｉ5/3 Ｏ4 を活物質として含む正
極と、リチウムイオンの吸蔵・放出が可能に炭素材料を
含む負極と、エチレンカーボネートを含む２成分以上の
混合溶媒に電解質としてのリチウムフルオロメタンスル
ホン酸イミドを溶解した非水電解液とを備えた構造を有
する。The non-aqueous electrolyte secondary battery according to the present invention described above includes a positive electrode containing Li 4/3 Ti 5/3 O 4 as an active material and a carbon material capable of inserting and extracting lithium ions. It has a structure including a negative electrode, and a non-aqueous electrolyte in which lithium fluoromethanesulfonic acid imide as an electrolyte is dissolved in a mixed solvent of two or more components including ethylene carbonate.
【００３３】このような構成によれば、正極活物質であ
るＬｉ4/3 Ｔｉ5/3 Ｏ4 はＬｉ+ ／Ｌｉ電位を基準にし
て１．５Ｖであり、負極材料である炭素材料はＬｉ+ ／
Ｌｉ電位を基準にして約０Ｖであるため、作動電位が
１．５Ｖ系の二次電池を実現できる。According to such a configuration, Li 4/3 Ti 5/3 O 4 as the positive electrode active material is 1.5 V with reference to the Li + / Li potential, and the carbon material as the negative electrode material is Li 4 + /
Since the voltage is about 0 V based on the Li potential, a 1.5 V secondary battery having an operating potential of 1.5 V can be realized.
【００３４】また、前記正極活物質であるＬｉ4/3 Ｔｉ
5/3 Ｏ4 は充放電の繰り返し時において高い放電維持率
を示し、かつ過充電状態にあっても、その結晶構造の変
化が起こらない特性を有する。The positive electrode active material Li 4/3 Ti
5/3 O 4 has such characteristics that it exhibits a high discharge retention rate during repeated charging and discharging and does not change its crystal structure even in an overcharged state.
【００３５】さらに、前記非水電解液を構成する電解質
であるリチウムフルオロメタンスルホン酸イミドは一般
的な電解質である六フッ化リン酸リチウムに比べて反応
抵抗が低く、電極との反応性を低減して自己放電の発生
を抑制できる。しかも、前記電解質が溶解される溶媒は
高誘電率で高粘性のエチレンカーボネートを含む。Further, lithium fluoromethanesulfonimide, which is an electrolyte constituting the non-aqueous electrolyte, has a lower reaction resistance than that of lithium hexafluorophosphate, which is a general electrolyte, and reduces reactivity with electrodes. As a result, the occurrence of self-discharge can be suppressed. In addition, the solvent in which the electrolyte is dissolved contains ethylene carbonate having a high dielectric constant and a high viscosity.
【００３６】したがって、前述したＬｉ4/3 Ｔｉ5/3 Ｏ
4 からなる正極活物質を含む正極と前記特定の電解質お
よび混合溶媒の組成を有する非水電解液との組み合わせ
により自己放電の発生を抑制し、かつ優れた充放電効率
やサイクル特性を有する非水電解液二次電池を提供する
ことができる。Therefore, the above-mentioned Li 4/3 Ti 5/3 O
The combination of a positive electrode containing a positive electrode active material consisting of 4 and a non-aqueous electrolyte having the composition of the specific electrolyte and the mixed solvent suppresses the occurrence of self-discharge, and a non-aqueous liquid having excellent charge / discharge efficiency and cycle characteristics. An electrolyte secondary battery can be provided.
【００３７】[0037]
【実施例】以下、本発明の好ましい実施例を詳細に説明
する。DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.
【００３８】（実施例１） ＜正極合剤の作製＞まず、水酸化リチウム（ＬｉＯＨ）
と酸化チタン（ＴｉＯ2 ）とをモル比が４：５になるよ
うに混合し、その混合物を窒素雰囲気中、８００℃で２
４時間焼成すことによりＬｉ4/3 Ｔｉ5/3 Ｏ4 を合成し
た。Example 1 <Preparation of Positive Electrode Mixture> First, lithium hydroxide (LiOH)
And titanium oxide (TiO 2 ) in a molar ratio of 4: 5, and the mixture is mixed at 800 ° C. for 2 hours in a nitrogen atmosphere.
By calcining for 4 hours, Li 4/3 Ti 5/3 O 4 was synthesized.
【００３９】次いで、得られたＬｉ4/3 Ｔｉ5/3 Ｏ4 粉
末１００重量部にカーボン１０重量部、ポリテトラフル
オロエチレン粉末５重量部を配合し、攪拌した後、得ら
れた混合物を５トン／ｃｍ2 で直径１６ｍｍ、厚さ０．
９ｍｍのペレット状に加圧成形した。つづいて、このペ
レットを１５０℃で５時間乾燥して正極合剤を作製し
た。Next, 10 parts by weight of carbon and 5 parts by weight of polytetrafluoroethylene powder were blended with 100 parts by weight of the obtained Li 4/3 Ti 5/3 O 4 powder, and the mixture was stirred. The diameter is 16 mm and the thickness is 0.1 ton / cm 2 .
It was press-formed into a 9 mm pellet. Subsequently, the pellet was dried at 150 ° C. for 5 hours to prepare a positive electrode mixture.
【００４０】＜負極合剤の作製＞メソフェーズピッチを
原料とするピッチ系炭素繊維を細かく粉砕し、２８００
℃の温度で焼成して炭素粉末を得た。つづいて、前記炭
素粉末９５重量部とスチレン・ブタジエンゴム５重量部
とを混合、攪拌した後、得られた混合物を５トン／ｃｍ
2 で直径１６ｍｍ、厚さ０．７ｍｍのペレット状に加圧
成形し、さらに１５０℃で５時間乾燥した。ひきつづ
き、このペレットにリチウムを電解含浸させることによ
り負極合剤を作製した。<Preparation of Negative Electrode Mixture> A pitch-based carbon fiber using mesophase pitch as a raw material is finely pulverized and
It was calcined at a temperature of ° C. to obtain a carbon powder. Subsequently, 95 parts by weight of the carbon powder and 5 parts by weight of styrene / butadiene rubber were mixed and stirred, and the obtained mixture was mixed at 5 tons / cm.
2 was pressed into a pellet having a diameter of 16 mm and a thickness of 0.7 mm, and dried at 150 ° C. for 5 hours. Subsequently, the pellets were electrolytically impregnated with lithium to prepare a negative electrode mixture.
【００４１】次いで、前記正極合剤を内面にコロイダル
カーボンを集電体として被覆したステンレス鋼からなる
正極缶に収納し、かつ前記負極合剤を内面に直径１０ｍ
ｍ、厚さ０．０５ｍｍのニッケル製エキスパンドメタル
を配置したステンレス鋼からなる負極缶に収納し、前述
した図１に示す構造の外径２０ｍｍ、厚さ０．５ｍｍの
コイン型リチウム二次電池を組み立てた。Next, the positive electrode mixture was housed in a positive electrode can made of stainless steel coated with colloidal carbon as a current collector on the inner surface, and the negative electrode mixture was coated on the inner surface with a diameter of 10 m.
m, placed in a negative electrode can made of stainless steel on which nickel expanded metal having a thickness of 0.05 mm is disposed, and a coin-type lithium secondary battery having an outer diameter of 20 mm and a thickness of 0.5 mm having the structure shown in FIG. Assembled.
【００４２】なお、非水電解液としてはリチウムフルオ
ロメタンスルホン酸イミド［ＬｉＮ（ＣＦ3 Ｓ
Ｏ2 ）2 ］をエチレンカーボネート（ＥＣ）およびγ−
ブチロラクトン（γ−ＢＬ）の混合溶媒（混合体積比率
１：２）に１．０モル／Ｌ溶解した組成のものを使用
し、この非水電解液をポリプロピレン不織布からなるセ
パレータに含浸させた。As the non-aqueous electrolyte, lithium fluoromethanesulfonimide [LiN (CF 3 S
O 2 ) 2 ] with ethylene carbonate (EC) and γ-
A non-aqueous electrolytic solution having a composition of 1.0 mol / L dissolved in a mixed solvent of butyrolactone (γ-BL) (mixing volume ratio 1: 2) was impregnated with a separator composed of a polypropylene nonwoven fabric.
【００４３】（比較例１〜４）非水電解液の成分である
混合溶媒および電解質として下記表１に示すものを用い
た以外、実施例１と同様で、前述した図１に示す構造の
４種のコイン型リチウム二次電池を組み立てた。(Comparative Examples 1 to 4) The same procedure as in Example 1 was carried out, except that the components shown in Table 1 below were used as the mixed solvent and the electrolyte as components of the nonaqueous electrolytic solution. Kind of coin-type lithium secondary batteries were assembled.
【００４４】得られた実施例１および比較例１〜４の二
次電池について、組み立て後に２０℃で７〜１４日間エ
ージングを行なった。なお、エージング後の開回路電圧
は３．２Ｖであった。The secondary batteries of Example 1 and Comparative Examples 1 to 4 were aged at 20 ° C. for 7 to 14 days after assembly. The open circuit voltage after aging was 3.2 V.
【００４５】エージング後の各二次電池について、２０
℃にて充電電流０．５ｍＡで２．５Ｖまで充電させた
後、放電電流０．５ｍＡで０．５Ｖまで放電させる充放
電を繰り返し、放電容量が初期の放電容量の５０％にな
るまでの充放電回数（サイクル数）を測定した。その結
果を下記表１に示す。For each secondary battery after aging, 20
After charging to 2.5 V at 0.5 mA with a charging current of 0.5 mA, charging and discharging were repeated until the discharging capacity reached 50% of the initial discharging capacity. The number of discharges (number of cycles) was measured. The results are shown in Table 1 below.
【００４６】[0046]
【表１】 [Table 1]
【００４７】前記表１から明らかなように非水電解液の
電解質としてリチウムフルオロメタンスルホン酸イミド
を用いた実施例１の二次電池は、非水電解液の電解質と
して過塩素酸リチウムのようなリチウムフルオロメタン
スルホン酸イミド以外のものを用いた比較例１〜４に比
べて放電容量が５０％低下するまでのサイクル数が２倍
以上になり、サイクル数の増加に伴う放電容量の低下が
少なく、優れた充放電サイクル特性を有することがわか
る。As is apparent from Table 1, the secondary battery of Example 1 using lithium fluoromethanesulfonimide as the electrolyte of the non-aqueous electrolyte was prepared by using lithium perchlorate as the electrolyte of the non-aqueous electrolyte. The number of cycles until the discharge capacity is reduced by 50% is twice or more as compared with Comparative Examples 1 to 4 using a substance other than lithium fluoromethanesulfonimide, and the decrease in the discharge capacity with an increase in the number of cycles is small. It can be seen that the battery has excellent charge / discharge cycle characteristics.
【００４８】（実施例２−１〜２−７および比較例５，
６）非水電解液としてエチレンカーボネート（ＥＣ）お
よびγ−ブチロラクトン（γ−ＢＬ）とを下記表２に示
す体積比で混合した混合溶媒にリチウムフルオロメタン
スルホン酸イミド［ＬｉＮ（ＣＦ3 ＳＯ2 ）2 ］を１．
０モル／Ｌ溶解した組成のものを使用した以外、実施例
１と同様で、前述した図１に示す構造の９種のコイン型
リチウム二次電池を組み立てた。(Examples 2-1 to 2-7 and Comparative Example 5,
6) Lithium fluoromethanesulfonimide [LiN (CF 3 SO 2 )] was mixed in a mixed solvent in which ethylene carbonate (EC) and γ-butyrolactone (γ-BL) were mixed at a volume ratio shown in Table 2 below as a non-aqueous electrolyte. 2 ] to 1.
Nine kinds of coin-type lithium secondary batteries having the above-described structure shown in FIG. 1 were assembled in the same manner as in Example 1, except that the composition having a composition of 0 mol / L was used.
【００４９】得られた実施例２−１〜２−７および比較
例５，６の二次電池について、実施例１と同様なエージ
ングを行な胃、さらに２０℃にて充電電流０．５ｍＡで
２．５Ｖまで充電させた後、放電電流０．５ｍＡで０．
５Ｖまで放電させ、それぞれ下記式に従って充放電効率
を求めた。その結果を下記表２に示す。The obtained secondary batteries of Examples 2-1 to 2-7 and Comparative Examples 5 and 6 were aged in the same manner as in Example 1 and were further charged at 20 ° C. with a charging current of 0.5 mA. After the battery was charged to 2.5 V, the discharge current was 0.5 mA and the discharge current was 0.5 mA.
The battery was discharged to 5 V, and the charge / discharge efficiency was calculated according to the following formula. The results are shown in Table 2 below.
【００５０】充放電効率（％）＝（放電容量／充電容
量）×１００Charge / discharge efficiency (%) = (discharge capacity / charge capacity) × 100
【表２】 [Table 2]
【００５１】前記表２から明らかなように溶媒としてＥ
Ｃとγ−ＢＬの混合溶媒を含む非水電解液を備えた実施
例２−１〜２−７の二次電池は、ＥＣ単独の溶媒を含む
非水電解液を備えた比較例５の二次電池およびγ−ＢＬ
単独の溶媒を含む非水電解液を備えた比較例６の二次電
池に比べて優れた充放電効率を有することがわかる。特
に、ＥＣが１０〜９０体積％のＥＣとγ−ＢＬの混合溶
媒を含む非水電解液を備えた実施例２−２〜２−６の二
次電池はより優れた充放電効率を示すことがわかる。As is clear from Table 2 above, E
The secondary batteries of Examples 2-1 to 2-7 including the non-aqueous electrolyte containing the mixed solvent of C and γ-BL are the same as those of Comparative Example 5 including the non-aqueous electrolyte containing the solvent of EC alone. Secondary battery and γ-BL
It can be seen that the battery has superior charge / discharge efficiency as compared with the secondary battery of Comparative Example 6 including the nonaqueous electrolyte containing a single solvent. In particular, the secondary batteries of Examples 2-2 to 2-6 each having a nonaqueous electrolyte containing a mixed solvent of EC and γ-BL having an EC of 10 to 90% by volume show more excellent charge / discharge efficiency. I understand.
【００５２】[0052]
【発明の効果】以上詳述したように本発明によれば、充
電時における非水電解液と電極の反応による自己放電の
発生を抑制し、かつ優れた充放電効率やサイクル特性を
有し、さらに１．５Ｖでの作動が可能でニッケルカドミ
ウム二次電池との互換性を持つ非水電解液二次電池を提
供することができる。As described above in detail, according to the present invention, the occurrence of self-discharge due to the reaction between the nonaqueous electrolyte and the electrode during charging is suppressed, and the battery has excellent charge / discharge efficiency and cycle characteristics. Furthermore, a non-aqueous electrolyte secondary battery that can operate at 1.5 V and is compatible with a nickel cadmium secondary battery can be provided.
【図１】本発明におけるコイン型非水電解液二次電池を
示す断面図。FIG. 1 is a sectional view showing a coin-type non-aqueous electrolyte secondary battery according to the present invention.
１…正極缶、 ２…正極、 ４…セパレータ、 ５…負極、 ７…負極缶。 DESCRIPTION OF SYMBOLS 1 ... Positive electrode can, 2 ... Positive electrode, 4 ... Separator, 5 ... Negative electrode, 7 ... Negative electrode can.
Claims (2)
む正極と、 リチウムイオンの吸蔵・放出が可能に炭素材料を含む負
極と、 エチレンカーボネートを含む２成分以上の混合溶媒に電
解質としてのリチウムフルオロメタンスルホン酸イミド
を溶解した非水電解液とを具備したことを特徴とする非
水電解液二次電池。1. A positive electrode containing Li 4/3 Ti 5/3 O 4 as an active material, a negative electrode containing a carbon material capable of inserting and extracting lithium ions, and a mixed solvent of two or more components containing ethylene carbonate. A non-aqueous electrolyte secondary battery comprising: a non-aqueous electrolyte in which lithium fluoromethanesulfonimide is dissolved as an electrolyte.
ンカーボネートが１０〜９０体積％の割合で含有される
ことを特徴とする請求項１記載の非水電解液二次電池。2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the mixed solvent in the non-aqueous electrolyte contains 10 to 90% by volume of ethylene carbonate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10186549A JP2000021445A (en) | 1998-07-01 | 1998-07-01 | Nonaqueous electrolyte secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10186549A JP2000021445A (en) | 1998-07-01 | 1998-07-01 | Nonaqueous electrolyte secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000021445A true JP2000021445A (en) | 2000-01-21 |
Family
ID=16190465
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10186549A Pending JP2000021445A (en) | 1998-07-01 | 1998-07-01 | Nonaqueous electrolyte secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2000021445A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100354231B1 (en) * | 2000-07-25 | 2002-09-27 | 삼성에스디아이 주식회사 | An Electrolyte for Lithium Sulfur batteries |
| KR100683455B1 (en) * | 1999-06-03 | 2007-02-15 | 타이탄 고교 가부시키가이샤 | Lithium-titanium composite oxides, processes for preparing them and uses thereof |
| JP2011216480A (en) * | 2010-03-19 | 2011-10-27 | Semiconductor Energy Lab Co Ltd | Nonaqueous electrolyte and lithium ion secondary battery |
-
1998
- 1998-07-01 JP JP10186549A patent/JP2000021445A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100683455B1 (en) * | 1999-06-03 | 2007-02-15 | 타이탄 고교 가부시키가이샤 | Lithium-titanium composite oxides, processes for preparing them and uses thereof |
| KR100354231B1 (en) * | 2000-07-25 | 2002-09-27 | 삼성에스디아이 주식회사 | An Electrolyte for Lithium Sulfur batteries |
| JP2011216480A (en) * | 2010-03-19 | 2011-10-27 | Semiconductor Energy Lab Co Ltd | Nonaqueous electrolyte and lithium ion secondary battery |
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