JP2000106187A - Nonaqueous electrolytic secondary battery - Google Patents
Nonaqueous electrolytic secondary batteryInfo
- Publication number
- JP2000106187A JP2000106187A JP10279080A JP27908098A JP2000106187A JP 2000106187 A JP2000106187 A JP 2000106187A JP 10279080 A JP10279080 A JP 10279080A JP 27908098 A JP27908098 A JP 27908098A JP 2000106187 A JP2000106187 A JP 2000106187A
- Authority
- JP
- Japan
- Prior art keywords
- potential
- secondary battery
- positive electrode
- carbon fiber
- active material
- 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
見度を有し、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という利点を有する。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 generally has a high energy rating, has little self-discharge during storage, and can take out current in a wide range of environmental temperatures of -20 to 60 ° C. Has advantages.
【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正極活物質とし
ては、例えば五酸化バナジウム、マンガン酸化物、リチ
ウムコバルト酸化物、リチウムニッケル酸化物、スピネ
ル型リチウムマンガン酸化物等が検討され、その一部が
実用化されている。As the positive electrode active material of the nonaqueous electrolyte secondary battery, for example, vanadium pentoxide, manganese oxide, lithium cobalt oxide, lithium nickel oxide, spinel lithium manganese oxide and the like have been studied. Department has 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、ＬｉxＴｉyＯ4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Ｌｉ4/3Ｔｉ5/3Ｏ4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Ｌｉ4/3Ｔｉ5/3Ｏ4材料は、充放電を１００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, it is known that the discharge potential of a material of x = 4/3 , y = 5/3 , that is, Li 4/3 Ti 5/3 O 4 shows 1.5 V based on the Li + / Li potential. I have. Such a Li 4/3 Ti 5/3 O 4 material shows a discharge maintenance rate of 95% or more even when charge and discharge are repeated for 100 cycles 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、ＬｉxＴｉyＯ4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
ＬｉxＴｉyＯ4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Ｌｉ2
ＭｎＯ3やＬｉＭｎＯ2を正極材料として用い、Ｌｉ4/3
Ｔｉ5/3Ｏ4またはＬｉＴｉ2Ｏ4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. Japanese Patent Application Laid-Open No. 7-320784 discloses Li2
MnO3 or LiMnO2 is used as a cathode material, and Li 4/3
It is disclosed that 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ＬｉxＴｉyＯ4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、ＬｉxＴｉyＯ4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、ＬｉxＴｉyＯ4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ＬｉxＴｉyＯ4
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 the positive electrode, the above-mentioned Li x Ti y O 4 is theoretically used.
Is expected to exhibit excellent overcharge characteristics, but 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正極
としては、活物質と例えばカーボンブラックのような導
電材と例えばポリテトラフルオロエチレンのような結着
材とを所定の割合で混練して調製し、成形して偏平状に
した、いわゆる正極合剤が知られている。On the other hand, a positive electrode used in a lithium secondary battery is prepared by kneading an active material, a conductive material such as carbon black and a binder such as polytetrafluoroethylene at a predetermined ratio. A so-called positive electrode mixture formed into a flat shape by molding is known.
【００１６】[0016]
【発明が解決しようとする課題】しかしながら、正極合
剤の導電材としてカーボンブラックを用いたリチウム二
次電池はサイクル特性等において必ずしも十分に満足す
るものではなかった。However, lithium secondary batteries using carbon black as the conductive material of the positive electrode mixture have not always been sufficiently satisfactory in cycle characteristics and the like.
【００１７】本発明は、優れた充電効率とサイクル特性
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。An object of the present invention is to provide a non-aqueous electrolyte secondary battery capable of operating at 1.5 V and having excellent charging efficiency and cycle characteristics.
【００１８】[0018]
【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、活物質としてのＬｉ4/3Ｔｉ5/3Ｏ4、導
電材および結着材を含む正極と、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、非水電解液とを
具備し、前記導電材は、気相法炭素繊維であることを特
徴とするものである。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, a conductive material and a binder, and a lithium ion A negative electrode containing a carbon material capable of occluding and releasing carbon, and a non-aqueous electrolyte, wherein the conductive material is a vapor grown carbon fiber.
【００１９】前記気相法炭素繊維は、前記活物質に対し
て５〜１０体積％の割合で含有されることが好ましい。It is preferable that the vapor grown carbon fiber is contained at a ratio of 5 to 10% by volume based on the active material.
【００２０】[0020]
【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。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.
【００２１】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―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。For example, in a positive electrode can 1 made of stainless steel,
The positive electrode 2 is housed. A current collector 3 such as colloidal carbon is provided on the inner surface of the positive electrode can 1 where the positive electrode 2 contacts.
Is coated. 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. The negative electrode can 7 and the positive electrode can 1 are caulked to form the positive electrode can 1.
The positive electrode 2, the separator 4 and the negative electrode 5 are hermetically sealed in the negative electrode can 7. 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.
【００２２】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.
【００２３】（１）正極２ この正極２は、Ｌｉ4/3Ｔｉ5/3Ｏ4からなる活物質と、
気相法炭素繊維からなる導電材と、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 ,
It is produced by press-molding a mixture containing a conductive material composed of vapor grown carbon fiber and a binder.
【００２４】前記気相法炭素繊維は、径が０．１〜０．
５μｍ、長さが１０〜１００μｍであることが好まし
い。The vapor-grown carbon fiber has a diameter of 0.1 to 0.1 mm.
Preferably, the length is 5 μm and the length is 10 to 100 μm.
【００２５】前記気相法炭素繊維は、前記活物質に対し
て５〜１０体積％の割合で含有することが好ましい。前
記気相法炭素繊維の割合を５体積％未満にすると、充電
効率が低下する恐れがある。一方、前記気相法炭素繊維
の割合が１０体積％を超えると二次電池のサイクル特性
が低下する恐れがある。The vapor grown carbon fiber is preferably contained at a ratio of 5 to 10% by volume based on the active material. When the ratio of the vapor grown carbon fiber is less than 5% by volume, the charging efficiency may be reduced. On the other hand, when the ratio of the vapor grown carbon fiber exceeds 10% by volume, the cycle characteristics of the secondary battery may be deteriorated.
【００２６】前記結着材としては、例えばポリテトラフ
ルオロエチレン等を用いることができる。As the binder, for example, polytetrafluoroethylene or the like can be used.
【００２７】（２）負極５ 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 5 This negative electrode 5 is made of a carbonaceous material that absorbs and releases lithium.
It is produced by press-molding a mixture comprising a conductive agent and a binder.
【００２８】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.
【００２９】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.
【００３０】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), carboxymethyl cellulose (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.
【００３１】（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.
【００３２】（４）非水電解液 この非水電解液は、非水溶媒に電解質を溶解した組成を
有する。(4) Nonaqueous Electrolyte This nonaqueous electrolyte has a composition in which an electrolyte is dissolved in a nonaqueous solvent.
【００３３】前記非水溶媒としては、例えばエチレンカ
ーボネート（ＥＣ）、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。
これらの溶媒は、１種または２種以上の混合物の形態で
用いることができる。Examples of the non-aqueous solvent include ethylene carbonate (EC) and 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.
These solvents can be used in the form of one kind or a mixture of two or more kinds.
【００３４】前記電解質としては、例えばホウフッ化リ
チウム（ＬｉＢＦ4 ）、六フッ化リン酸リチウム（Ｌｉ
ＰＦ6 ）、過塩素酸リチウム（ＬｉＣｌＯ4 ）、六フッ
化砒素リチウム（ＬｉＡｓＦ6 ）、トリフルオロメタン
スルホン酸リチウム（ＬｉＣＦ3 ＳＯ3 ）、塩化アルミ
ニウムリチウム（ＬｉＡｌＣｌ）、リチウムフルオロメ
タンスルホン酸イミド［ＬｉＮ（ＣＦ3ＳＯ2）2］から
選ばれる１種または２種以上のリチウム塩を挙げること
ができる。Examples of the electrolyte include lithium borofluoride (LiBF 4 ) and lithium hexafluorophosphate (Li
PF 6 ), lithium perchlorate (LiClO 4 ), lithium arsenic hexafluoride (LiAsF 6 ), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), lithium aluminum chloride (LiAlCl), lithium fluoromethanesulfonimide [LiN (CF 3 SO 2 ) 2 ], and one or more lithium salts.
【００３５】前記電解質の非水溶媒に対する溶解量は、
０．５〜１．５モル／ｌとすることが望ましい。The amount of the electrolyte dissolved in the non-aqueous solvent is as follows:
It is desirably 0.5 to 1.5 mol / l.
【００３６】以上説明した本発明に係わる非水電解液二
次電池は、活物質としてのＬｉ4/3Ｔｉ5/3Ｏ4、導電材
としての気相法炭素繊維および結着材を含む正極と、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、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 has a positive electrode containing Li 4/3 Ti 5/3 O 4 as an active material, vapor-grown carbon fiber as a conductive material, and a binder. And a negative electrode containing a carbon material capable of inserting and extracting lithium ions, and a non-aqueous electrolyte.
【００３７】このような構成によれば、正極活物質であ
るＬｉ4/3Ｔｉ5/3Ｏ4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+／Ｌ
ｉ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 + / L
Since it is about 0 V with respect to the i potential, the operating potential is 1.
A 5V secondary battery can be realized.
【００３８】また、前記正極活物質であるＬｉ4/3Ｔｉ
5/3Ｏ4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。Further, 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.
【００３９】さらに、前記導電材としての気相法炭素繊
維は膨張・収縮に対する強度が高く、水分吸着がファー
ネスブラックのような従来使用されている導電材に比べ
て低く、かつ電気電導性が優れている。その結果、この
導電材を含む正極は充填密度の向上と非水電解液の浸透
性の改善が図られるため、充電効率とサイクル特性が向
上された非水電解液二次電池を実現できる。Further, the vapor grown carbon fiber as the conductive material has a high strength against expansion and contraction, has a lower moisture adsorption than conventional conductive materials such as furnace black, and has excellent electric conductivity. ing. As a result, the positive electrode containing the conductive material has an improved filling density and an improved permeability of the non-aqueous electrolyte, thereby realizing a non-aqueous electrolyte secondary battery having improved charging efficiency and cycle characteristics.
【００４０】[0040]
【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.
【００４１】（実施例１） ＜正極の作製＞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２４時
間焼成すことによりＬｉ4/3Ｔｉ5/3Ｏ4を合成した。Example 1 <Preparation of Positive Electrode> First, lithium hydroxide (LiOH) and titanium oxide (TiO 2 ) were mixed at a molar ratio of 4: 5, and the mixture was placed in a nitrogen atmosphere. By firing at 800 ° C. for 24 hours, Li 4/3 Ti 5/3 O 4 was synthesized.
【００４２】次いで、得られたＬｉ4/3Ｔｉ5/3Ｏ4粉末
（活物質）に平均径０．２μｍ、長さ４０〜５０μｍの
気相法炭素繊維（黒鉛化品）、ポリテトラフルオロエチ
レン粉末を配合した。なお、前記気相法炭素繊維は前記
活物質に対して１０体積％配合し、前記ポリテトラフル
オロエチレン粉末は前記活物質に対して５体積％配合し
た。前記混合物を攪拌した後、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時間乾燥して正極を作製した。Next, a vapor-grown carbon fiber (graphitized product) having an average diameter of 0.2 μm and a length of 40 to 50 μm was added to the obtained Li 4/3 Ti 5/3 O 4 powder (active material), Ethylene powder was blended. The vapor grown carbon fiber was blended at 10% by volume based on the active material, and the polytetrafluoroethylene powder was blended at 5% by volume based on the active material. After stirring the mixture, the resulting mixture was pressed into a pellet having a diameter of 16 mm and a thickness of 0.9 mm at 5 ton / cm 2 . Subsequently, the pellet was dried at 150 ° C. for 5 hours to produce a positive electrode.
【００４３】＜負極の作製＞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／ｃｍ2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
を作製した。<Preparation of Negative Electrode> A pitch-based carbon fiber using mesophase pitch as a raw material was finely ground and fired at a temperature of 2800 ° C. to obtain a carbon powder. Subsequently, after mixing and stirring 95 parts by weight of the carbon powder and 5 parts by weight of styrene-butadiene rubber, the resulting mixture is pressed at 5 tons / cm 2 into pellets having a diameter of 16 mm and a thickness of 0.7 mm. It was molded and dried at 150 ° C. for 5 hours. Subsequently, the pellet was electrolytically impregnated with lithium to produce a negative electrode.
【００４４】次いで、前記正極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、かつ前記負極を内面に直径１０ｍｍ、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、さらにこれら
正負極間にホウフッ化リチウム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
組成の非水電解液が含浸されたポリプロピレン不織布か
らなるセパレータを配置することにより前述した図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 was housed in a stainless steel positive electrode can coated with colloidal carbon as a current collector on the inner surface, and a nickel expanded metal having a diameter of 10 mm and a thickness of 0.05 mm was arranged on the inner surface. The lithium borofluoride was placed between the positive and negative electrodes in a mixed solvent of ethylene carbonate (EC) and γ-butyrolactone (γ-BL) (mixing volume ratio 1: 2). 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.
【００４５】（比較例１〜３）正極の導電材として下記
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３種のコイン型リチウム二次電池
を組み立てた。(Comparative Examples 1 to 3) Three types of coin-type lithium secondary batteries having the structure shown in FIG. 1 described above in the same manner as in Example 1 except that the conductive materials for the positive electrode shown in Table 1 below were used. Was assembled.
【００４６】得られた実施例１および比較例１〜３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 obtained secondary batteries of Example 1 and Comparative Examples 1 to 3 were aged at 20 ° C. for 7 to 14 days after assembly. The open circuit voltage after aging was 3.2 V.
【００４７】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.
【００４８】[0048]
【表１】 [Table 1]
【００４９】前記表１から明らかなように導電材として
気相法炭素繊維を含む正極を備えた実施例１の二次電池
は、導電材としてケッチェンブラック、アセチレンブラ
ック、ファーネスブラックを含む正極を備えた比較例１
〜３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 clear from Table 1, the secondary battery of Example 1 provided with a positive electrode containing vapor grown carbon fiber as a conductive material used a positive electrode containing Ketjen black, acetylene black, and furnace black as a conductive material. Comparative Example 1 provided
The number of cycles until the discharge capacity is reduced by 50% is twice or more as compared with Nos. 3 to 3, and it can be seen that the decrease in the discharge capacity with the increase in the number of cycles is small and that the battery has excellent charge / discharge cycle characteristics.
【００５０】（実施例２−１〜２−７）正極としてＬｉ
4/3Ｔｉ5/3Ｏ4粉末（活物質）と平均径０．２μｍ、長
さ４０〜５０μｍの気相法炭素繊維（黒鉛化品）とポリ
テトラフルオロエチレン粉末とを下記表２に示す体積比
率で混合したものを用いた以外、実施例１と同様で、前
述した図１に示す構造の７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) Li as a positive electrode
Table 2 shows 4/3 Ti 5/3 O 4 powder (active material), vapor-grown carbon fiber (graphitized product) having an average diameter of 0.2 μm and a length of 40 to 50 μm, and polytetrafluoroethylene powder. Seven 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 mixture at a volume ratio was used.
【００５１】得られた実施例２−１〜２−７の二次電池
について、実施例１と同様な方法により充放電回数（サ
イクル数）を測定した。With respect to the obtained secondary batteries of Examples 2-1 to 2-7, the number of charge / discharge (cycle) was measured in the same manner as in Example 1.
【００５２】また、実施例２−１〜２−７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い、さらに２
０℃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。Further, the secondary batteries of Examples 2-1 to 2-7 were subjected to the same aging as in Example 1, and
After charging at 0 ° C. to 0.5 V at a charging current of 0.5 mA, the battery was discharged to 0.5 V at a discharging current of 0.5 mA, and the charging / discharging efficiency was calculated according to the following equations. The results are shown in Table 2 below.
【００５３】 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]
【００５４】前記表２から明らかなように気相法炭素繊
維をＬｉ4/3Ｔｉ5/3Ｏ4粉末（活物質）に対して５〜１
０体積％で配合した正極を備えた実施例２−２〜２−６
の二次電池は、前記気相法炭素繊維が５体積％未満の実
施例２−１の二次電池に比べて充放電効率が高く、かつ
前記気相法炭素繊維が１０体積％を超える実施例２−７
の二次電池に比べてサイクル数が大きくなることがわか
る。As is apparent from Table 2, the vapor-grown carbon fiber was added to Li 4/3 Ti 5/3 O 4 powder (active material) in an amount of 5 to 1%.
Examples 2-2 to 2-6 provided with a positive electrode mixed at 0% by volume
In the secondary battery, the charge / discharge efficiency is higher than that of the secondary battery of Example 2-1 in which the vapor grown carbon fiber is less than 5% by volume, and the vapor grown carbon fiber exceeds 10% by volume. Example 2-7
It can be seen that the number of cycles is larger than that of the secondary battery.
【００５５】[0055]
【発明の効果】以上詳述したように本発明によれば、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 in detail above, according to the present invention, excellent charge / discharge efficiency and cycle characteristics,
And a non-aqueous electrolyte secondary battery compatible with a nickel cadmium secondary battery.
【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)
電材および結着材を含む正極と、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、非水電解液とを
具備し、 前記導電材は、気相法炭素繊維であることを特徴とする
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 conductive material and a binder, a negative electrode containing a carbon material capable of inserting and extracting lithium ions, and a non-aqueous electrolysis. A non-aqueous electrolyte secondary battery, wherein the conductive material is a vapor grown carbon fiber.
して５〜１０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 vapor grown carbon fiber is contained at a ratio of 5 to 10% by volume based on the active material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10279080A JP2000106187A (en) | 1998-09-30 | 1998-09-30 | Nonaqueous electrolytic secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10279080A JP2000106187A (en) | 1998-09-30 | 1998-09-30 | Nonaqueous electrolytic secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000106187A true JP2000106187A (en) | 2000-04-11 |
Family
ID=17606145
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10279080A Pending JP2000106187A (en) | 1998-09-30 | 1998-09-30 | Nonaqueous electrolytic secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2000106187A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003147641A (en) * | 2001-08-29 | 2003-05-21 | Gsi Creos Corp | Carbon fiber produced by vapor growth method, electrode material for battery, and method for producing the carbon fiber |
| US6858349B1 (en) | 2000-09-07 | 2005-02-22 | The Gillette Company | Battery cathode |
| WO2006097586A1 (en) * | 2004-07-02 | 2006-09-21 | Commissariat A L'energie Atomique | Method of charging a lithium-ion battery comprising a negative electrode |
| JP2011060764A (en) * | 2009-09-09 | 2011-03-24 | Samsung Sdi Co Ltd | Negative electrode active material for lithium secondary battery, this manufacturing method, and lithium secondary battery containing this |
| JP2012195100A (en) * | 2011-03-15 | 2012-10-11 | Sumitomo Electric Ind Ltd | Molten salt battery |
-
1998
- 1998-09-30 JP JP10279080A patent/JP2000106187A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6858349B1 (en) | 2000-09-07 | 2005-02-22 | The Gillette Company | Battery cathode |
| JP2003147641A (en) * | 2001-08-29 | 2003-05-21 | Gsi Creos Corp | Carbon fiber produced by vapor growth method, electrode material for battery, and method for producing the carbon fiber |
| WO2006097586A1 (en) * | 2004-07-02 | 2006-09-21 | Commissariat A L'energie Atomique | Method of charging a lithium-ion battery comprising a negative electrode |
| US7671568B2 (en) | 2004-07-02 | 2010-03-02 | Commissariat A L'energie Atomique | Method of charging a lithium-ion battery comprising a negative electrode |
| JP2011060764A (en) * | 2009-09-09 | 2011-03-24 | Samsung Sdi Co Ltd | Negative electrode active material for lithium secondary battery, this manufacturing method, and lithium secondary battery containing this |
| US8530095B2 (en) | 2009-09-09 | 2013-09-10 | Samsung Sdi Co., Ltd. | Negative active material for rechargeable lithium battery, method of preparing same, and rechargeable lithium battery including same |
| JP2012195100A (en) * | 2011-03-15 | 2012-10-11 | Sumitomo Electric Ind Ltd | Molten salt battery |
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