JPH05283063A - Negative electrode for lithium secondary battery and lithium secondary battery using same electrode - Google Patents

Negative electrode for lithium secondary battery and lithium secondary battery using same electrode

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Publication number
JPH05283063A
JPH05283063A JP4076668A JP7666892A JPH05283063A JP H05283063 A JPH05283063 A JP H05283063A JP 4076668 A JP4076668 A JP 4076668A JP 7666892 A JP7666892 A JP 7666892A JP H05283063 A JPH05283063 A JP H05283063A
Authority
JP
Japan
Prior art keywords
carbon
negative electrode
secondary battery
carbon fiber
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.)
Pending
Application number
JP4076668A
Other languages
Japanese (ja)
Inventor
Yoshiteru Nakagawa
喜照 中川
Akihiro Mabuchi
昭弘 馬淵
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Osaka Gas Co Ltd
Original Assignee
Osaka Gas Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Osaka Gas Co Ltd filed Critical Osaka Gas Co Ltd
Priority to JP4076668A priority Critical patent/JPH05283063A/en
Publication of JPH05283063A publication Critical patent/JPH05283063A/en
Pending legal-status Critical Current

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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

PURPOSE:To prevent the deterioration of capability due to a drop in electrical conductivity by constituting a negative electrode of a carbon material comprising a stacked composite member of carbon powder and a carbon film. CONSTITUTION:A negative electrode 1 is constituted of the stack of a film layer 1 and a carbon fiber layer 2. The film layer 1 is made of a carbon material allowing the doping an dedoping of alkaline metal, such as a film made of coal and oil mesophase pitch, and can be used as a host for intercalation reaction. The carbon fiber layer 2 is made of a carbon material allowing the doping and dedoping of alkaline metal or the like, such as vapor phase growth carbon fiber, PAN, phenol and rayon carbon fiber and pitch carbon fiber, and can be used as a host for intercalation reaction. According to this construction, the deterioration of capability due to a drop in electrical conductivity can be prevented and output density can be improved.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、リチウム二次電池およ
びリチウム二次電池用負極、さらに詳しくは、炭素繊維
を他のカーボン材と複合化することにより、カーボン材
として炭素繊維のみを負極構成要素に用いた従来のタイ
プの場合に見られた製造プロセス上の難点を解決し、し
かも性能的にもかかる従来タイプのものと比べてより大
きな放電容量・出力密度および優れたサイクル特性が得
られるリチウム二次電池およびリチウム二次電池用負極
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery and a negative electrode for a lithium secondary battery, more specifically, by compounding carbon fiber with another carbon material, only carbon fiber is used as a negative electrode in the negative electrode structure. It solves the problems in the manufacturing process found in the conventional type used for the element, and also has a larger discharge capacity / power density and superior cycle characteristics compared to the conventional type that also has high performance. The present invention relates to a lithium secondary battery and a negative electrode for a lithium secondary battery.

【０００２】[0002]

【従来の技術】負極活物質としてリチウム、正極活物質
として金属カルコゲン化物、金属酸化物を用い、電解液
として非プロトン性有機溶媒に種々の塩を溶解させたも
のを用いた、いわゆるリチウム二次電池は高エネルギー
密度型二次電池の一種として注目され、盛んに研究が行
われている。2. Description of the Related Art A so-called lithium secondary battery in which lithium is used as a negative electrode active material, metal chalcogenide and a metal oxide are used as a positive electrode active material, and various salts are dissolved in an aprotic organic solvent is used as an electrolytic solution. Batteries are attracting attention as a type of high energy density secondary battery and are being actively researched.

【０００３】しかしながら、従来のリチウム電池では、
負極活物質としてのリチウムは箔状の如き単体で用いら
れることが多く、充放電を繰り返すうちに、樹枝状リチ
ウムが析出して両極が短絡するため充放電のサイクル寿
命が短いという欠点を有する。However, in the conventional lithium battery,
Lithium as a negative electrode active material is often used as a simple substance such as a foil, and has a drawback that the cycle life of charge / discharge is short because dendritic lithium is deposited and both electrodes are short-circuited during repeated charge / discharge.

【０００４】そこで、アルミニウムや、鉛、カドミウム
及びインジウムを含む可融性合金を用い、充電時にリチ
ウムを合金として析出させ、放電時には合金からリチウ
ムを溶解させる方法が提案されている［米国特許第４,
００２,４９２号（１９７７）参照］。しかし、このよ
うな方法では、樹枝状リチウムの析出は抑止できるが、
エネルギー密度は低下する。Therefore, a method has been proposed in which a fusible alloy containing aluminum, lead, cadmium, and indium is used to deposit lithium as an alloy during charging and to dissolve lithium from the alloy during discharging [US Pat. ,
002, 492 (1977)]. However, although such a method can prevent the deposition of dendritic lithium,
Energy density decreases.

【０００５】さらに、放電容量を向上させることを目的
に、リチウムをカーボン材に担持させようという試みも
種々行われている。例えば、種々の繊維状、あるいは粉
末状のカーボン材を用いる試みがなされている［東芝電
池（株）および三菱油化（株）共願の特開昭６３−１１
４０５６号（１９８８）、三菱瓦斯化学（株）出願の特
開昭６２−２６８０５６号（１９８７）参照］。Further, various attempts have been made to support lithium on a carbon material for the purpose of improving discharge capacity. For example, attempts have been made to use various fibrous or powdery carbon materials [Toshiba Battery Co., Ltd. and Mitsubishi Petrochemical Co., Ltd. joint application JP-A-63-11].
No. 4056 (1988), Japanese Patent Application Laid-Open No. 62-268056 (1987) filed by Mitsubishi Gas Chemical Co., Inc.].

【０００６】[0006]

【発明が解決しようとする課題】前記したごとき種々の
カーボン材のうち、カーボン材として炭素繊維のみを負
極構成要素とした従来のリチウム二次電池では、必要と
される導電性を確保するために金属性の集電体を使用す
るため、軽量化が図れず、また電池を組立てる時にエッ
ジ部でセパレータを損傷する等、特性上あるいは製造プ
ロセス上の問題があった。また、集電体を用いない場合
には電気伝導度が低下し、その結果満足する性能が得ら
れないことも大きな問題であり、特に出力密度の問題は
顕著で改善が要望されていた。本発明の課題は、これら
の問題点を解決することにある。Among the various carbon materials as described above, in the conventional lithium secondary battery in which only carbon fiber is used as the carbon material as the negative electrode constituent element, in order to ensure the required conductivity, Since a metallic current collector is used, weight reduction cannot be achieved, and there are problems in characteristics or in the manufacturing process, such as damage to the separator at the edge when assembling the battery. Further, when the current collector is not used, the electric conductivity is lowered, and as a result, a satisfactory performance cannot be obtained, which is a big problem. Particularly, the problem of the output density is remarkable, and improvement thereof has been demanded. An object of the present invention is to solve these problems.

【０００７】[0007]

【課題を解決するための手段】かかる事情に鑑み、本発
明者らは、炭素繊維を他のカーボン材と複合化すること
に着目し、複合化の相手となる種々のカーボン材を試み
た結果、炭素フィルムを用いることにより、意外にも前
記課題を解決できることを見出し、本発明を完成するに
至った。In view of the above circumstances, the present inventors have focused their attention on compounding carbon fiber with other carbon materials, and have tried various carbon materials to be compounded. Surprisingly, they have found that the above problems can be solved by using a carbon film, and completed the present invention.

【０００８】すなわち、本発明は、炭素繊維および炭素
フィルムを積層複合化したカーボン材よりなるリチウム
二次電池用負極を提供するものである。以下、図面を参
照して本発明のリチウム二次電池用負極を説明する。図
１は本発明のリチウム二次電池用負極を模式的に示す断
面図である。図１を参照し、本発明のリチウム二次電池
用負極はフィルム層（１）と炭素繊維層（２）よりなる
積層構造を有する。このように用いるカーボン材とし
て、炭素フィルムを炭素繊維と組み合わせ、かつ積層構
造とすることにより、始めて本発明の目的が達成される
ものである。That is, the present invention provides a negative electrode for a lithium secondary battery, which is made of a carbon material obtained by laminating and compositing carbon fibers and a carbon film. Hereinafter, the negative electrode for a lithium secondary battery of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view schematically showing the negative electrode for a lithium secondary battery of the present invention. Referring to FIG. 1, the negative electrode for a lithium secondary battery of the present invention has a laminated structure including a film layer (1) and a carbon fiber layer (2). As the carbon material used in this way, the object of the present invention is achieved for the first time by combining a carbon film with carbon fibers and forming a laminated structure.

【０００９】まず、フィルム層（１）では炭素フィルム
を用いる。この炭素フィルムとしては、アルカリ金属等
をドープ・脱ドープし得る炭素材でインターカレーショ
ン反応のホストとして使用できるものであればいずれの
ものでもよく、例えば、石炭系・石油系のメソフェーズ
ピッチを原料とするフィルムが使用でき、この場合、等
方性ピッチをある程度含んでいても支障はない。炭素フ
ィルム１枚の厚みは、一般に、１０〜４０μｍの範囲内
とする。First, a carbon film is used for the film layer (1). The carbon film may be any carbon material capable of being doped / dedoped with an alkali metal or the like and used as a host for an intercalation reaction. For example, a coal-based or petroleum-based mesophase pitch is used as a raw material. The film can be used, and in this case, there is no problem even if it contains some isotropic pitch. The thickness of one carbon film is generally within the range of 10 to 40 μm.

【００１０】一方、炭素繊維層（２）で用いる炭素繊維
としては、アルカリ金属等をドープ・脱ドープし得る炭
素材でインターカレーション反応のホストとして使用で
きるものであればいずれのものでもよい。例えば、炭素
繊維の種類としては、気相成長炭素繊維・ＰＡＮ系、フ
ェノール系、レーヨン系炭素繊維・ピッチ系炭素繊維な
どが使用できる。その形態としては、第１の態様におい
て、繊維径は１〜２０μｍ、繊維長は０.１５〜４０ｍ
ｍの範囲のミルド化したものを使用する。この形態の場
合には、加工時におけるバインダーとの均一な混合が可
能となり、また電池とした場合には、用いる電解質、溶
媒等の保液性に必要なバルキーさを保持できる利点があ
る。他の態様において、使用する炭素繊維の形態として
は、長繊維の織物（クロス）、繊維束、短繊維からなる
マット、フェルト、ペーパー等を本発明の負極の構成要
素として使用できる。On the other hand, the carbon fiber used in the carbon fiber layer (2) may be any carbon material which can be doped or dedoped with an alkali metal or the like and can be used as a host for the intercalation reaction. For example, as the type of carbon fiber, vapor-grown carbon fiber / PAN-based, phenol-based, rayon-based carbon fiber / pitch-based carbon fiber and the like can be used. As the form, in the first embodiment, the fiber diameter is 1 to 20 μm, and the fiber length is 0.15 to 40 m.
A milled product in the range of m is used. In the case of this form, it is possible to uniformly mix with the binder during processing, and in the case of a battery, there is an advantage that the bulkiness required for retaining liquid such as electrolyte and solvent to be used can be maintained. In another embodiment, as the form of the carbon fiber to be used, a woven fabric (cloth) of long fibers, a fiber bundle, a mat made of short fibers, felt, paper and the like can be used as a constituent element of the negative electrode of the present invention.

【００１１】本発明のリチウム二次電池用負極は、かか
る材料を用いたフィルム層および炭素繊維層を交互に何
層か積層してなり、実際の電池の構成要素とするに際し
ては、該積層構造体を所望の形状・寸法に裁断して使用
する。The negative electrode for a lithium secondary battery of the present invention comprises a plurality of film layers and carbon fiber layers using such a material, which are alternately laminated. When the negative electrode for a lithium secondary battery is used as a component of an actual battery, the laminated structure is used. The body is cut into the desired shape and size for use.

【００１２】次に、積層構造体の製法について説明す
る。いくつかの製法が考えられるが、第１の例として、
成型後かつ不融化前の炭素フィルムをその表面が接着性
を保てるような温度に保持しながら、ミルド化した炭素
繊維の噴流床の中を通過させその表面に炭素繊維を付着
させたものを不融化する。得られた炭素繊維付着フィル
ムの数枚から数１０枚を積層し、ホットプレスしてフィ
ルム層と炭素繊維層が交互に積層されたシートが得られ
る。別法として、炭化・黒鉛化工程を経た炭素フィルム
に炭素繊維と適量のバインダーを混合したものを塗布
し、それらを積層した後、プレス機にてプレス成型し
て、炭素フィルムと炭素繊維層（＋バインダー）が交互
に積層したシートが得られる。Next, a method of manufacturing the laminated structure will be described. Several manufacturing methods are possible, but as the first example,
While maintaining the temperature of the carbon film after molding and before infusibilization at such a level that the surface can maintain its adhesiveness, the carbon film passed through the jetted bed of milled carbon fiber and adhered to the surface To melt. Several to several tens of the obtained carbon fiber-attached films are laminated and hot pressed to obtain a sheet in which film layers and carbon fiber layers are alternately laminated. Alternatively, a carbon film that has undergone a carbonization / graphitization process is coated with a mixture of carbon fiber and an appropriate amount of binder, and after laminating them, press molding is performed with a press machine to form a carbon film and a carbon fiber layer ( A sheet in which + binder) are alternately laminated is obtained.

【００１３】ここに、本発明で用いることができる炭素
フィルム自体の製法例を参考のために記載する。最初の
工程では、溶融したピッチをスリット状ノズルから押し
出して、フィルム状ないしはシート状の形状を付与す
る。かかる工程用の装置が図２〜図４に示す押出装置で
ある。An example of the method for producing the carbon film itself that can be used in the present invention will be described here for reference. In the first step, the melted pitch is extruded from a slit-shaped nozzle to give a film-like or sheet-like shape. The apparatus for such a process is the extrusion apparatus shown in FIGS.

【００１４】まず、図１を参照し、溶融ピッチを装置
（３）に供給し、スリット型ノズル（６）（図４参照）
からシート状に押し出し、次いで押し出されたシート状
ピッチ（４）を巻取装置（５）に牽引して巻取る。装置
（３）には、フィルム状ないしはシート状にて巻き取る
ことができるように工夫がなされている。First, referring to FIG. 1, a molten pitch is supplied to an apparatus (3), and a slit type nozzle (6) (see FIG. 4).
The sheet-shaped pitch (4) is extruded in a sheet shape from the sheet, and then the sheet-shaped pitch (4) is pulled by the winding device (5) and wound up. The device (3) is devised so that it can be wound up in the form of a film or a sheet.

【００１５】即ち、装置（３）には、シート状ピッチ
（４）の軸方向両端面近傍に向けて且つスリット中央点
Ｃを通るスリット長さ方向に垂直な仮想面Ｐに対称な方
向に、外向成分および下向成分の分力を有する気流を吹
き付けるための少なくとも２個の気流吹出口（７）が設
けられている。That is, in the device (3), toward the vicinity of both axial end faces of the sheet-like pitch (4) and in a direction symmetrical to an imaginary plane P perpendicular to the slit length direction passing through the slit center point C, At least two airflow outlets (7) are provided for blowing an airflow having component forces of an outward component and a downward component.

【００１６】このように複数の気流吹出口を配すること
により、スリット型ノズル（６）から出て巻取装置
（５）に牽引されつつあるシート状ピッチ（４）が十分
に固化する前に、換言すればまだスリット型ノズル
（６）の直下に位置する時点で、シート状ピッチ（４）
の幅方向両端部近傍に気流を吹き付けて当該シート状ピ
ッチ（４）を幅方向に広げる分力を作用させることによ
り、ネックダウン現象が抑制されて、広幅のテープ状ピ
ッチフィルム（８）が得られる。By arranging a plurality of air flow outlets in this way, before the sheet-like pitch (4) which is being drawn out from the slit type nozzle (6) and being pulled by the winding device (5) is sufficiently solidified. In other words, at the time when it is still directly below the slit type nozzle (6), the sheet-like pitch (4)
The neck down phenomenon is suppressed and a wide tape-shaped pitch film (8) is obtained by blowing an air current in the vicinity of both ends in the width direction of the sheet to exert a component force for expanding the sheet-shaped pitch (4) in the width direction. Be done.

【００１７】吹付気体は、５０〜１００ｍ／秒程度の速
度（気流吹出口の出口での速度）で吹き付けることが好
ましく、また、吹付量は、気流吹出口１箇所当たり０.
４〜０.５リットル／分程度とすることが好ましい。吹
付気体の種類としては、空気、窒素、ガス燃焼廃ガス等
を使用することができる。その温度は、通常、シート状
ピッチ（４）が巻取により延伸され得る２００〜４００
℃の範囲とし、好ましくは２５０〜３５０℃の範囲とす
る。気流吹出口（７）は、シート状ピッチ（４）の両端
部近傍に両面から気流が吹き付けることができるよう
に、各端部近傍に少なくとも２箇所ずつ、合計して少な
くとも４箇所に設けるのが好ましい。The blowing gas is preferably blown at a velocity of about 50 to 100 m / sec (velocity at the outlet of the airflow outlet), and the amount of the air blown is 0.1 per airflow outlet.
It is preferably about 4 to 0.5 liter / minute. Air, nitrogen, gas combustion waste gas, or the like can be used as the type of sprayed gas. The temperature is usually 200 to 400 at which the sheet-like pitch (4) can be stretched by winding.
C., preferably 250 to 350.degree. The airflow outlets (7) are provided at least at two places near each end so that the airflow can be blown from both sides near the ends of the sheet-like pitch (4), and at least at a total of four places. preferable.

【００１８】次の工程では、炭素繊維の製造で採用され
ている常法に準じ、先の工程で得られたピッチフィルム
（通常厚さ１２〜５０μｍ、幅２〜４５ｍｍ）を不融化
する。この不融化工程は後の炭素化、黒鉛化においてフ
ィルム状ないしはシート状を保持することを目的とす
る。In the next step, the pitch film (usually 12 to 50 μm in thickness and 2 to 45 mm in width) obtained in the previous step is infusibilized according to a conventional method used in the production of carbon fibers. This infusibilizing step is intended to maintain a film or sheet shape in the subsequent carbonization and graphitization.

【００１９】不融化は、例えば、空気雰囲気中、２８０
〜３４０℃の範囲の温度で行うことができる。不融化に
要する時間は、シート状ピッチの厚みに応じて適宜選択
することができ、薄い程短時間で完了できる。The infusibilization is performed, for example, in an air atmosphere at 280
It can be carried out at a temperature in the range of ˜340 ° C. The time required for infusibilization can be appropriately selected according to the thickness of the sheet-like pitch, and the thinner the time, the shorter the time required for completion.

【００２０】最後の工程となる前記不融化物の焼成は、
所望するカーボン材フィルムの電気抵抗に応じた温度で
行うことができる。即ち、焼成温度が高くなるにつれ
て、炭化度、黒鉛化度が高くなり、電気抵抗の小さな炭
素化は、不活性雰囲気（窒素、二酸化炭素、アルゴン等
の雰囲気）中、１０００〜２０００℃の範囲の温度で行
うことができる。また、不融化物の黒鉛化は、アルゴン
等の雰囲気中、２０００〜３０００℃の範囲の温度で行
うことができる。The firing of the infusible substance as the final step is as follows.
It can be performed at a temperature according to the desired electrical resistance of the carbon material film. That is, as the firing temperature becomes higher, the degree of carbonization and the degree of graphitization become higher, and carbonization with a low electric resistance is performed in an inert atmosphere (an atmosphere such as nitrogen, carbon dioxide, or argon) in the range of 1000 to 2000 ° C. It can be done at temperature. Further, graphitization of the infusibilized product can be performed at a temperature in the range of 2000 to 3000 ° C. in an atmosphere such as argon.

【００２１】以上の工程により、通常は厚みが１０〜４
０μｍ、幅が１.５〜４５ｍｍ程度のカーボン材フィル
ムが得られる。これを適当な寸法に裁断して、本発明の
負極で用いることができる。By the above steps, the thickness is usually 10 to 4
A carbon material film having a width of 0 μm and a width of about 1.5 to 45 mm is obtained. This can be cut into an appropriate size and used in the negative electrode of the present invention.

【００２２】次に、本発明のリチウム二次電池用負極に
おいて、前記積層体の形状としては、最終的な用途・電
池の形状に応じ、シート状・棒状・板状・膜状等種々の
形態とし得る。サイズとしては、厚みが０.０５〜１ｍ
ｍ、幅が１.５〜１５０ｍｍの範囲とし、長さは特に限
定されず、適宜所望の長さに裁断できる。このような形
態とすることにより本発明のリチウム二次電池用負極が
得られる。Next, in the negative electrode for a lithium secondary battery of the present invention, the laminated body may have various shapes such as a sheet shape, a rod shape, a plate shape, and a film shape, depending on the final use and the shape of the battery. Can be As for size, the thickness is 0.05-1m
The width m is in the range of 1.5 to 150 mm, and the length is not particularly limited, and can be appropriately cut into a desired length. With such a form, the negative electrode for a lithium secondary battery of the present invention can be obtained.

【００２３】かかる本発明の二次電池用負極は、通常用
いられるプロピレンカーボネート、エチレンカーボネー
ト、γ−ブチロラクトン、テトラヒドロフラン、２−メ
チルテトラヒドロフラン、ジオキソラン、４−メチルジ
オキソラン、スルホラン、アセトニトリル等の電解液、
Ｖ2Ｏ5、Ｍｎ2Ｏ等の正極と組み合わせて、常法によ
り、リチウム二次電池に組み立てることができる。本発
明はこのようなリチウム二次電池も提供するものであ
り、ポータブル電子機器等の電源、その他各種メモリー
やソーラーのバックアップ等、さらには電気自動車、電
力貯蔵用バッテリーなどに好適に使用することができ
る。The negative electrode for a secondary battery according to the present invention is an electrolyte such as propylene carbonate, ethylene carbonate, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, 4-methyldioxolane, sulfolane, acetonitrile, etc.
A lithium secondary battery can be assembled by a conventional method in combination with a positive electrode such as V 2 O 5 or Mn 2 O. The present invention also provides such a lithium secondary battery, and can be suitably used as a power source for portable electronic devices and the like, backup of various memories and solars, and also as an electric vehicle, a battery for power storage, and the like. it can.

【００２４】次に、上記した炭素繊維と炭素フィルムの
複合体を用いることによる効果を説明する。まず、炭素
繊維と炭素フィルムの複合化により、（１）炭素繊維を
単独で用いた場合に比べ、導電性が大幅に向上し、充放
電反応の速度が向上し、従来必要とされた金属性集電体
が不必要となり、軽量化が図れる、（２）炭素フィルム
を単独で用いた場合に比べ、バルキーな構造となり、負
極への電解液等の拡散が容易となる気孔が形成される、
等の作用により、充放電反応が容易となり、その結果出
力密度が向上する。Next, the effect of using the above-mentioned composite of carbon fiber and carbon film will be described. First, by combining carbon fiber and carbon film, (1) compared with the case where carbon fiber is used alone, the conductivity is significantly improved, the speed of charge / discharge reaction is improved, and the metallic property conventionally required. A current collector is unnecessary, and weight reduction can be achieved. (2) A bulky structure is formed as compared with the case where a carbon film is used alone, and pores are formed that facilitate diffusion of an electrolytic solution or the like into a negative electrode.
Due to such actions, the charge / discharge reaction is facilitated, and as a result, the output density is improved.

【００２５】また、炭素繊維単独の場合にみられた電池
組立時の炭素繊維のエッジ部によるセパレータの損傷等
の問題が解決される。また、結晶子に層状構造をもつカ
ーボン材を二次電池の電極に用いた場合、充放電の際に
層間に化学種が侵入・脱離するが、それに伴って結晶子
のｃ軸方向への膨張・収縮が起こる。この膨張・収縮が
繰り返されると、電極面と平行方向に歪みが増加し、つ
いには電極の破壊が起こる。しかして、本発明における
ハイブリッド構造のカーボン材では結晶子のａ軸方向が
電極面と平行に配向したものを使用しているため、その
膨張・収縮が電極面と垂直方向に起こることになり、電
極は破壊されにくく長寿命化が可能となる。Further, problems such as damage of the separator due to the edge portion of the carbon fiber at the time of assembling the battery, which are observed when the carbon fiber is used alone, are solved. Further, when a carbon material having a layered structure in the crystallite is used for an electrode of a secondary battery, chemical species enter / extract between layers during charging / discharging. Expansion / contraction occurs. When the expansion and contraction are repeated, the strain increases in the direction parallel to the electrode surface, and eventually the electrode breaks down. In the carbon material of the hybrid structure in the present invention, the crystallites whose a-axis direction is oriented parallel to the electrode surface are used, so that the expansion / contraction thereof occurs in the direction perpendicular to the electrode surface. The electrode is less likely to be broken and the life can be extended.

【００２６】さらに、電池特性に大きく影響を及ぼす因
子として、電気伝導性や熱伝導性が挙げられる。カーボ
ンのπ電子は炭素原子の六角網目構造による共役系の中
で移動するため、カーボン結晶の配向の乱れは電気伝導
性の低下やジュール熱の増加をもたらす原因となる。し
かして、本発明で使用するハイブリッド構造のカーボン
材では、炭素フィルム側の結晶子のａ軸が電極面と平行
に配向しているため、電気・熱伝導性に対する異方性が
顕著に発現する。その結果、集電効果を高める方向の電
気伝導性とジュール熱の移動・放熱を容易にする方向の
熱伝導性の両特性を電池用電極に付与することができ
る。Further, as factors that greatly affect the battery characteristics, electrical conductivity and thermal conductivity can be mentioned. Since the π-electrons of carbon move in the conjugated system of the hexagonal network structure of carbon atoms, the disorder of the orientation of the carbon crystal causes a decrease in electrical conductivity and an increase in Joule heat. In the carbon material of the hybrid structure used in the present invention, the a-axis of the crystallite on the carbon film side is oriented parallel to the electrode surface, so that anisotropy with respect to electric / thermal conductivity is remarkably exhibited. .. As a result, the battery electrode can be provided with both the electrical conductivity in the direction of increasing the current collecting effect and the thermal conductivity in the direction of facilitating the movement and heat dissipation of Joule heat.

【００２７】また、炭素繊維および炭素フィルムと、い
ずれもリチウムイオンを吸蔵可能な材料を複合化させる
ことにより、両者の長所を相補的に生かせることができ
ると共に、負極体当たりに吸蔵されるリチウムイオンの
量、即ち放電容量を高めることができる。By compositing carbon fiber and carbon film with a material capable of absorbing lithium ions, the advantages of both can be complementarily utilized and the lithium ions stored per negative electrode body can be complemented. , The discharge capacity can be increased.

【００２８】[0028]

【実施例】以下に実施例を挙げて本発明をさらに詳しく
説明する。 ［炭素繊維とペーストの調製］光学的等方性のピッチ系
炭素繊維をミルド化したもの（繊維径１３μｍ、繊維長
０.１５ｍｍ）を使用した。上記炭素繊維にディスパー
ジョンタイプのＰＴＦＥ（濃度１０％）を重量比で９
０：１０で混合し、ペースト状とした。EXAMPLES The present invention will be described in more detail with reference to the following examples. [Preparation of Carbon Fiber and Paste] Optically isotropic pitch-based carbon fiber milled (fiber diameter 13 μm, fiber length 0.15 mm) was used. 9% by weight of dispersion type PTFE (concentration 10%) to the above carbon fiber
The mixture was mixed at 0:10 to form a paste.

【００２９】［炭素フィルムの調製］ 軟化点（メトラー法）＝１００℃、キノリン不溶分（Ｑ
Ｉ成分）＝０.２％、 ベンゼン不溶分（ＢＩ成分）＝３０％のコールタールピ
ッチに２倍量の水素化アントラセン油を加え、４３０℃
で６０分間加熱し、さらに減圧下３００℃で水素化アン
トラセン油を除去して還元ピッチを得た。次いで、この
還元ピッチに窒素ガスを導入して、低分子量成分を除去
し、４００℃で５時間熱重合して、軟化点（メトラー
法）＝２６２.４℃、ＱＩ成分＝５０％、ＢＩ成分＝９
８％、メソフェーズ含有量９０％以上の押出用メソフェ
ーズピッチを得た。このピッチを図２〜図４に示した装
置を使用し、前記ピッチを溶融状態にてスリット型ノズ
ル（６）から押し出し、空気を吹き付けつつ巻き取るこ
とによって、シート状ピッチ系フィルムを得た。次い
で、該ピッチ系フィルムを空気中３℃／分の昇温速度で
３００℃まで加熱した後、同温度に２時間保持すること
によって不融化処理を行った。その後、アルゴン中、１
０００℃で加熱焼成してテープ状ピッチ系炭素フィルム
を得た。具体的製造条件と、得られたテープ状ピッチ系
炭素フィルムの性状を表１に示す。[Preparation of carbon film] Softening point (Mettler method) = 100 ° C., quinoline insoluble matter (Q
I component) = 0.2%, benzene insoluble content (BI component) = 30% coal tar pitch, and double the amount of hydrogenated anthracene oil was added at 430 ° C.
The mixture was heated at 60 ° C. for 60 minutes, and the hydrogenated anthracene oil was removed at 300 ° C. under reduced pressure to obtain reduced pitch. Then, nitrogen gas was introduced into this reduced pitch to remove low molecular weight components, and thermal polymerization was carried out at 400 ° C. for 5 hours to give a softening point (Mettler method) = 262.4 ° C., QI component = 50%, BI component. = 9
A mesophase pitch for extrusion having 8% and a mesophase content of 90% or more was obtained. This pitch was extruded from the slit type nozzle (6) in a molten state using the apparatus shown in FIGS. 2 to 4 and was wound while blowing air to obtain a sheet pitch film. Next, the pitch-based film was heated to 300 ° C. in air at a temperature rising rate of 3 ° C./min, and then held at the same temperature for 2 hours for infusibilization treatment. Then in argon, 1
A tape-shaped pitch-based carbon film was obtained by heating and firing at 000 ° C. Table 1 shows specific production conditions and properties of the obtained tape-shaped pitch-based carbon film.

【００３０】[0030]

【表１】 [Table 1]

【００３１】［負極体の作成］上記炭素フィルム上にコ
ーティングマシーンを用いて、ミルド状炭素繊維を含む
ペーストを塗布し、乾燥させた。得られたペースト付き
炭素フィルムを１０枚積層し、２６０℃で１０分間プレ
スして板状の負極体を得た。得られた負極体を作用極と
して、対極および参照極にリチウム金属を用いて、電位
が０Ｖになるまで負極体にリチウムを吸蔵させた。この
条件（電解液、電流密度等）は、以後行う電池特性の測
定の条件と同様にして行った。[Preparation of Negative Electrode Body] A paste containing milled carbon fiber was applied onto the carbon film using a coating machine and dried. Ten pieces of the obtained carbon film with a paste were laminated and pressed at 260 ° C. for 10 minutes to obtain a plate-shaped negative electrode body. Using the obtained negative electrode body as a working electrode, lithium metal was used for the counter electrode and the reference electrode, and lithium was stored in the negative electrode body until the potential became 0V. The conditions (electrolyte solution, current density, etc.) were the same as the conditions for the subsequent measurement of battery characteristics.

【００３２】［電池の作成］図５にその断面図を示すご
とく、前記にて得られた負極体（９）の他、正極体（１
０）として電解二酸化マンガンを、電解液として１モル
／ｌの濃度にＬｉＣｌＯ4を溶解させたプロピレンカー
ボネートを用い、セパレータ（１１）としてポリプロピ
レン不織布、さらにケース（１２）、封口板（１３）お
よび絶縁パッキング（１４）を用い、常法によりリチウ
ム二次電池を作成した。[Preparation of Battery] As shown in the sectional view of FIG. 5, in addition to the negative electrode body (9) obtained above, a positive electrode body (1
Electrolytic manganese dioxide is used as 0), propylene carbonate in which LiClO 4 is dissolved at a concentration of 1 mol / l is used as an electrolytic solution, polypropylene nonwoven fabric is used as a separator (11), and further a case (12), a sealing plate (13) and an insulating material. A lithium secondary battery was prepared by a conventional method using the packing (14).

【００３３】［電池特性の測定］前記にて得られたリチ
ウム二次電池の出力密度、放電容量およびサイクル特性
を測定した。測定は、通常、５０ｍＡ／ｇ（負極カーボ
ン基準）の定電流充放電下で行い、放電容量は、電池電
圧が２.０Ｖに低下するまでの容量とした。サイクル特
性は、放電容量が初期放電容量の９０％にまで低下する
までのサイクル数で評価した。また、出力密度は放電電
流密度を変化させて得た電流−電位曲線から求めた。対
照として、負極のカーボン材として、上記した炭素繊維
を単独で用いる以外は同様にして作成したリチウム二次
電池についても同条件下で測定を行った。結果を表２に
示す。[Measurement of Battery Characteristics] The output density, discharge capacity and cycle characteristics of the lithium secondary battery obtained above were measured. The measurement was usually performed under a constant current charge / discharge of 50 mA / g (negative electrode carbon standard), and the discharge capacity was defined as the capacity until the battery voltage dropped to 2.0V. The cycle characteristics were evaluated by the number of cycles until the discharge capacity decreased to 90% of the initial discharge capacity. The output density was obtained from the current-potential curve obtained by changing the discharge current density. As a control, a lithium secondary battery prepared in the same manner except that the above carbon fiber was used alone as the carbon material of the negative electrode was also measured under the same conditions. The results are shown in Table 2.

【００３４】[0034]

【表２】 [Table 2]

【００３５】表２より、本発明のリチウム二次電池は対
照リチウム二次電池よりも、放電容量、サイクル特性、
出力密度いずれの点においても優れていることが分か
る。As shown in Table 2, the lithium secondary battery of the present invention was superior to the control lithium secondary battery in discharge capacity, cycle characteristics,
It can be seen that the power density is excellent in both respects.

【００３６】[0036]

【発明の効果】本発明により、負極用カーボン材として
炭素繊維のみを用いた従来のものと比べて、軽量で、製
造プロセス的にも有利で、しかも性能的にも、出力密度
が大で単位体積（重量）当たりの容量が増大し、サイク
ル特性が向上したリチウム二次電池およびそのための負
極が提供される。EFFECTS OF THE INVENTION According to the present invention, compared with the conventional one using only carbon fiber as the carbon material for the negative electrode, it is light in weight, advantageous in the manufacturing process, and in terms of performance, the output density is large and the unit Provided is a lithium secondary battery having an increased capacity per volume (weight) and improved cycle characteristics, and a negative electrode therefor.

【図面の簡単な説明】[Brief description of drawings]

【図１】 本発明のリチウム二次電池用負極を模式的に
示す断面図である。FIG. 1 is a cross-sectional view schematically showing a negative electrode for a lithium secondary battery of the present invention.

【図２】 炭素フィルムを製造するための押出装置の概
要を示す斜視図である。FIG. 2 is a perspective view showing an outline of an extrusion apparatus for producing a carbon film.

【図３】 図２に示した押出装置の正面図である。FIG. 3 is a front view of the extrusion device shown in FIG.

【図４】 図２に示した押出装置のノズルと気流噴き出
し口を特に強調して示す概要図である。FIG. 4 is a schematic diagram showing the nozzle and the air flow outlet of the extrusion device shown in FIG. 2 with particular emphasis.

【図５】 実施例で作成した本発明のリチウム二次電池
の断面図である。FIG. 5 is a cross-sectional view of a lithium secondary battery of the present invention created in an example.

【符号の説明】[Explanation of symbols]

１：フィルム層、２：炭素繊維層、３：押出装置、４：
シート状ピッチ、５：巻取装置、６：スリット型ノズ
ル、７：気流噴き出し口、８：テープ状ピッチフィル
ム、９：負極、１０：正極、１１：セパレータ、１２：
ケース、１３：封口板、１４：絶縁パッキング1: film layer, 2: carbon fiber layer, 3: extrusion device, 4:
Sheet-like pitch, 5: winding device, 6: slit type nozzle, 7: air flow ejection port, 8: tape-like pitch film, 9: negative electrode, 10: positive electrode, 11: separator, 12:
Case, 13: sealing plate, 14: insulating packing

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 炭素繊維および炭素フィルムを積層複合
化したカーボン材よりなるリチウム二次電池用負極。1. A negative electrode for a lithium secondary battery, comprising a carbon material obtained by laminating and compositing carbon fibers and a carbon film. 【請求項２】 請求項１記載の負極を電池構成要素とし
てなるリチウム二次電池。2. A lithium secondary battery comprising the negative electrode according to claim 1 as a battery constituent element.
JP4076668A 1992-03-31 1992-03-31 Negative electrode for lithium secondary battery and lithium secondary battery using same electrode Pending JPH05283063A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP4076668A JPH05283063A (en) 1992-03-31 1992-03-31 Negative electrode for lithium secondary battery and lithium secondary battery using same electrode

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4076668A JPH05283063A (en) 1992-03-31 1992-03-31 Negative electrode for lithium secondary battery and lithium secondary battery using same electrode

Publications (1)

Publication Number Publication Date
JPH05283063A true JPH05283063A (en) 1993-10-29

Family

ID=13611799

Family Applications (1)

Application Number Title Priority Date Filing Date
JP4076668A Pending JPH05283063A (en) 1992-03-31 1992-03-31 Negative electrode for lithium secondary battery and lithium secondary battery using same electrode

Country Status (1)

Country Link
JP (1) JPH05283063A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0997603A (en) * 1995-09-29 1997-04-08 Toray Ind Inc Manufacture of electrode sheet for battery
JPH09312160A (en) * 1996-05-22 1997-12-02 Osaka Gas Co Ltd Manufacture of lithium secondary battery and carbonaceous negative electrode material to be used for lithium secondary battery

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0997603A (en) * 1995-09-29 1997-04-08 Toray Ind Inc Manufacture of electrode sheet for battery
JPH09312160A (en) * 1996-05-22 1997-12-02 Osaka Gas Co Ltd Manufacture of lithium secondary battery and carbonaceous negative electrode material to be used for lithium secondary battery

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