JPH05290837A - Lithium secondary battery - Google Patents
Lithium secondary batteryInfo
- Publication number
- JPH05290837A JPH05290837A JP4116930A JP11693092A JPH05290837A JP H05290837 A JPH05290837 A JP H05290837A JP 4116930 A JP4116930 A JP 4116930A JP 11693092 A JP11693092 A JP 11693092A JP H05290837 A JPH05290837 A JP H05290837A
- Authority
- JP
- Japan
- Prior art keywords
- negative electrode
- battery
- lithium secondary
- secondary battery
- binder
- 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
Landscapes
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、リチウム二次電池に係
わり、特にサイクル特性の向上を目的とした負極の改良
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery, and more particularly to improvement of a negative electrode for improving cycle characteristics.
【0002】[0002]
【従来の技術及び発明が解決しようとする課題】従来、
リチウム二次電池の負極の一つとして、コークスや黒鉛
等のリチウムを吸蔵放出可能な炭素粉末と、結着剤とし
てのポリビニリデンフルオライド(PVdF)とからな
る混合物を、溶剤としてのN−メチルピロリドンに分散
させたスラリーを、金属製の箔の両面にドクターブレー
ド法により塗布し、乾燥してなる積層体シートが使用さ
れている。2. Description of the Related Art Conventionally, the problems to be solved by the invention
As one of the negative electrodes of a lithium secondary battery, a mixture of carbon powder such as coke and graphite capable of occluding and releasing lithium and polyvinylidene fluoride (PVdF) as a binder, N-methyl as a solvent A laminate sheet is used in which a slurry dispersed in pyrrolidone is applied to both sides of a metal foil by a doctor blade method and dried.
【0003】かかる負極の場合、図4にその模式的断面
図を示すように、炭素粉末を結着剤にて結着させてなる
負極層41は集電体42に対して、接着されているわけ
ではなく、単に圧接されているに過ぎない。In the case of such a negative electrode, as shown in the schematic sectional view of FIG. 4, a negative electrode layer 41 formed by binding carbon powder with a binder is adhered to a current collector 42. It's not that it's just crimped.
【0004】このため、従来のリチウム二次電池には、
充放電を繰り返すうちに、負極層41の一部が集電体4
2から離脱して、電池容量が低下し易いという問題があ
った。Therefore, the conventional lithium secondary battery is
While charging and discharging were repeated, a part of the negative electrode layer 41 became the current collector 4.
There is a problem that the battery capacity is likely to decrease when the battery is separated from 2.
【0005】本発明は、かかる問題を解決するべくなさ
れたものであって、その目的とするところは、従来のリ
チウム二次電池に比し、充放電サイクルの繰り返しに伴
う電池容量の低下が少ない、すなわちサイクル特性に優
れたリチウム二次電池を提供するにある。The present invention has been made to solve the above problems, and an object of the present invention is to reduce a decrease in battery capacity due to repeated charge / discharge cycles as compared with a conventional lithium secondary battery. That is, it is to provide a lithium secondary battery having excellent cycle characteristics.
【0006】[0006]
【課題を解決するための手段】上記目的を達成するため
の本発明に係るリチウム二次電池(以下、「本発明電
池」と称する。)は、その負極が、リチウムを吸蔵放出
可能な炭素粉末を結着剤にて一体化してなる結着体シー
トからなるものである。A lithium secondary battery according to the present invention (hereinafter referred to as "the present battery") for achieving the above object has a carbon powder whose negative electrode is capable of inserting and extracting lithium. It is composed of a binder sheet obtained by integrating the above with a binder.
【0007】リチウムを吸蔵放出可能な炭素粉末として
は、黒鉛及びコークスが挙げられるが、なかでも黒鉛が
リチウムの吸蔵放出可能な量が多い点で好ましい。[0007] Examples of the carbon powder capable of occluding and releasing lithium include graphite and coke. Among them, graphite is preferable because it has a large amount of occluding and releasing lithium.
【0008】炭素粉末の一体化に使用する結着剤として
は、ポリプロピレン樹脂(PP)、ポリエチレン樹脂
(PE)、ポリエチレンテレフタレート樹脂(PET)
が例示される。As the binder used for integrating the carbon powder, polypropylene resin (PP), polyethylene resin (PE), polyethylene terephthalate resin (PET)
Is exemplified.
【0009】本発明における負極は、たとえば、リチウ
ムを吸蔵放出可能な炭素粉末と結着剤粉末とを、均一に
混合してスラリーとした後、結着剤の溶融温度(たとえ
ばポリプロピレン樹脂の場合、分子量によっても異なる
が通常180°C程度)に加熱保持し、この加熱保持し
たスラリーを、目的とする正極の厚みに応じた所定の厚
み(通常、0.1〜0.3mm)のスリットを備える押
出成型機を使用して、押し出し、急冷することにより作
製される。In the negative electrode of the present invention, for example, carbon powder capable of inserting and extracting lithium and binder powder are uniformly mixed to form a slurry, and then the melting temperature of the binder (for example, in the case of polypropylene resin, The slurry is heated and held at a temperature of about 180 ° C. although it varies depending on the molecular weight, and the heated and held slurry is provided with a slit having a predetermined thickness (usually 0.1 to 0.3 mm) according to the thickness of the target positive electrode. It is prepared by extrusion and quenching using an extruder.
【0010】負極を作製する際の結着剤粉末とリチウム
を吸蔵放出可能な炭素粉末との混合比率は、使用する各
粉末の種類によっても異なるが、一般に結着剤粉末5〜
50重量%、すなわち炭素粉末50〜95重量%が好ま
しい。なお、結着剤粉末は、これを多量に配合すると導
電性の低下を招くので、20重量%を越えて配合しない
ことがより好ましい。The mixing ratio of the binder powder and the carbon powder capable of occluding and releasing lithium during the production of the negative electrode varies depending on the type of each powder used, but generally the binder powder 5 to
50% by weight, i.e. 50 to 95% by weight of carbon powder, is preferred. It should be noted that it is more preferable not to mix the binder powder in excess of 20% by weight, because if a large amount of the binder powder is added, the conductivity will be lowered.
【0011】本発明電池は、サイクル特性を向上させる
ために、従来の積層体シートからなる負極が有していた
集電体からの負極層の離脱という問題を、かかる離脱の
虞れが全くない結着体シートからなる負極を使用した点
に特徴を有する。それゆえ、正極、非水系電解質、セパ
レータ(液体電解質を使用する場合)などについては、
従来リチウム二次電池用として使用され、或いは提案さ
れている種々の材料を制限なく使用することが可能であ
る。The battery of the present invention has no problem of separation of the negative electrode layer from the current collector, which the negative electrode composed of the conventional laminate sheet has, in order to improve the cycle characteristics. It is characterized in that a negative electrode made of a binder sheet is used. Therefore, regarding the positive electrode, non-aqueous electrolyte, separator (when using liquid electrolyte), etc.,
Various materials conventionally used or proposed for lithium secondary batteries can be used without limitation.
【0012】たとえば、リチウムを吸蔵放出可能な正極
活物質としては、無機化合物として、Li2 FeO3 、
TiO2 、V2 O5 などのトンネル状の空孔を有する酸
化物や、TiS2 、MoS2 等の層状構造を有する金属
カルコゲン化物が例示されるが、組成式Lix MO2 又
はLiy M2 O4 (ただし、Mは遷移元素、0≦x≦
1、0≦y≦2)で表される複合酸化物が好ましく、こ
の具体例としては、LiCoO2 、LiMnO2 、Li
NiO2 、LiCrO2 、LiMn2 O4 が例示され
る。これらの正極活物質は、常法により、アセチレンブ
ラック、カーボンブラック等の導電剤及びポリテトラフ
ルオロエチレン(PTFE)、ポリフッ化ビニリデン等
の結着剤と混練して正極合剤として使用される。For example, as a positive electrode active material capable of inserting and extracting lithium, an inorganic compound such as Li 2 FeO 3 ,
Examples thereof include oxides having tunnel-shaped vacancies such as TiO 2 and V 2 O 5 and metal chalcogenides having a layered structure such as TiS 2 and MoS 2 , but the composition formula Li x MO 2 or Li y M 2 O 4 (where M is a transition element, 0 ≦ x ≦
1, 0 ≦ y ≦ 2) is preferable, and specific examples thereof include LiCoO 2 , LiMnO 2 , and Li.
Examples are NiO 2 , LiCrO 2 , and LiMn 2 O 4 . These positive electrode active materials are kneaded by a conventional method with a conductive agent such as acetylene black or carbon black and a binder such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride to be used as a positive electrode mixture.
【0013】また、電解質についても、エチレンカーボ
ネート、ジメチルカーボネート、又はこれらの混合溶媒
にLiPF6 やLiClO4 等の溶質を溶かした溶液な
ど、種々の非水系電解質を用いることができる。As the electrolyte, various non-aqueous electrolytes such as ethylene carbonate, dimethyl carbonate, or a solution of a solute such as LiPF 6 or LiClO 4 dissolved in a mixed solvent thereof can be used.
【0014】[0014]
【作用】本発明電池においては、負極が積層体シートで
はなく結着体シートからなるので、積層体シートからな
る負極を使用していた従来電池において問題となってい
た、負極層が集電体から離脱するという問題が生じな
い。In the battery of the present invention, since the negative electrode is not the laminate sheet but the binder sheet, the negative electrode layer has been a problem in the conventional battery using the laminate sheet negative electrode. There is no problem of leaving.
【0015】[0015]
【実施例】以下、本発明を実施例に基づいてさらに詳細
に説明するが、本発明は下記実施例により何ら限定され
るものではなく、その要旨を変更しない範囲において適
宜変更して実施することが可能なものである。EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples, and various modifications can be made without departing from the scope of the invention. Is possible.
【0016】(実施例1) 〔正極の作製〕炭酸コバルトと炭酸リチウムとをCo:
Liの原子比1:1で混合した後、空気中で900°C
で20時間加熱処理してLiCoO2 を得た。このよう
にして得た正極活物質としてのLiCoO2 に、導電剤
としてのアセチレンブラックと、結着剤としてのフッ素
樹脂ディスパージョンとを、重量比90:6:4の比率
で混合して正極合剤を得た。この正極合剤を集電体とし
てのアルミニウム箔に圧延し、250°Cで2時間真空
下で加熱処理して正極を作製した。Example 1 [Preparation of Positive Electrode] Cobalt carbonate and lithium carbonate were mixed with Co:
After mixing Li at an atomic ratio of 1: 1 at 900 ° C in air
And heat treated for 20 hours to obtain LiCoO 2 . LiCoO 2 as a positive electrode active material thus obtained was mixed with acetylene black as a conductive agent and a fluororesin dispersion as a binder in a weight ratio of 90: 6: 4. I got an agent. This positive electrode mixture was rolled into an aluminum foil as a current collector and heat-treated under vacuum at 250 ° C. for 2 hours to produce a positive electrode.
【0017】〔負極の作製〕天然黒鉛粉末85重量部
に、結着剤としてのポリプロピレン樹脂15重量部を加
え180°Cで均一に混合してスラリーとした後、同温
度に加熱保持した。次いで、この加熱保持したスラリー
を、押出成型機(スリット幅:30cm、スリット厚:
0.2mm)により押し出し、急冷して負極を作製し
た。図1は、このようにして作製した負極1の模式的断
面図であり、天然黒鉛粉末2がポリプロピレン樹脂3に
より結着されて一体化されている様子を示す。[Preparation of Negative Electrode] 15 parts by weight of a polypropylene resin as a binder was added to 85 parts by weight of natural graphite powder, and the mixture was uniformly mixed at 180 ° C. to form a slurry, which was then heated and maintained at the same temperature. Then, the slurry held under heating was extruded (slit width: 30 cm, slit thickness:
0.2 mm) and then rapidly cooled to prepare a negative electrode. FIG. 1 is a schematic cross-sectional view of the negative electrode 1 produced in this manner, showing a state in which the natural graphite powder 2 is bound and integrated with the polypropylene resin 3.
【0018】〔電解液の調製〕エチレンカーボネートと
ジメチルカーボネートとの等体積混合溶媒に、LiPF
6 を1モル/リットル溶かして電解液を調製した。[Preparation of Electrolyte Solution] LiPF 6 was added to an equal volume mixed solvent of ethylene carbonate and dimethyl carbonate.
An electrolytic solution was prepared by dissolving 6 at 1 mol / liter.
【0019】〔本発明電池BA1の作製〕以上の正負両
極及び電解液を用いて本発明に係る円筒型のリチウム二
次電池BA1を作製した(電池寸法:直径14.2m
m;長さ:50.0mm)。なお、セパレータとしてイ
オン透過性のポリプロピレン製の微孔性薄膜を用いた。[Preparation of Battery BA1 of the Present Invention] A cylindrical lithium secondary battery BA1 according to the present invention was prepared using the positive and negative electrodes and the electrolytic solution described above (battery size: diameter 14.2 m).
m; length: 50.0 mm). As the separator, an ion-permeable polypropylene microporous thin film was used.
【0020】図2は作製した電池BA1の断面図であ
り、同図に示す電池BA1は、正極21及び負極22、
これら両電極を離隔するセパレータ23、正極リード2
4、負極リード25、正極外部端子26、負極缶27な
どからなる。正極21及び負極22は非水電解液が注入
されたセパレータ23を介して渦巻き状に巻き取られた
状態で負極缶27内に収容されており、正極21は正極
リード24を介して正極外部端子26に、また負極22
は負極リード25を介して負極缶27に接続され、電池
BA1内部で生じた化学エネルギーを電気エネルギーと
して外部へ取り出し得るようになっている。FIG. 2 is a sectional view of the manufactured battery BA1. The battery BA1 shown in FIG.
Separator 23 that separates these two electrodes, positive electrode lead 2
4, a negative electrode lead 25, a positive electrode external terminal 26, a negative electrode can 27, and the like. The positive electrode 21 and the negative electrode 22 are housed in a negative electrode can 27 in a state of being spirally wound via a separator 23 in which a nonaqueous electrolytic solution is injected, and the positive electrode 21 is connected to a positive electrode external terminal via a positive electrode lead 24. 26, and the negative electrode 22
Is connected to a negative electrode can 27 via a negative electrode lead 25, and chemical energy generated inside the battery BA1 can be taken out as electric energy to the outside.
【0021】(比較例1)天然黒鉛粉末85重量部と、
結着剤としてのポリビニリデンフルオライド15重量部
とを混合し、これを溶剤としてのN−メチルピロリドン
に分散させてスラリーとし、このスラリーをアルミニウ
ム箔の両面にドクターブレード法により塗布し、乾燥し
て負極を作製した。この負極を使用したこと以外は、実
施例1と同様にして、比較電池BC1を作製した。Comparative Example 1 85 parts by weight of natural graphite powder,
15 parts by weight of polyvinylidene fluoride as a binder is mixed, and this is dispersed in N-methylpyrrolidone as a solvent to form a slurry, and the slurry is applied to both sides of an aluminum foil by a doctor blade method and dried. To produce a negative electrode. A comparative battery BC1 was produced in the same manner as in Example 1 except that this negative electrode was used.
【0022】(各電池のサイクル特性)本発明電池BA
1及び比較電池BC1について、充電電流200mAで
充電終止電圧4.1Vまで充電した後、放電電流200
mAで放電終止電圧3Vまで放電する工程を1サイクル
とするサイクル試験を行い、各電池のサイクル特性を調
べた。(Cycle characteristics of each battery) Battery BA of the present invention
1 and the comparative battery BC1 were charged at a charging current of 200 mA to a charge end voltage of 4.1 V, and then discharged at a discharge current of 200
A cycle test in which the process of discharging to a discharge end voltage of 3 V at mA was defined as one cycle was performed to examine the cycle characteristics of each battery.
【0023】図3は、各電池のサイクル特性を、縦軸に
電池容量(mAh)を、また横軸にサイクル数(回)を
とって示したグラフである。同図より、本発明電池BA
1は、サイクル数400回においても初期の電池容量
(500mAh)を保持しているのに対して、比較電池
BC1では、サイクル初期から急激に電池容量が低下
し、サイクル数250回において250mAh弱にまで
電池容量が減少してしまうことが分かる。FIG. 3 is a graph showing the cycle characteristics of each battery, with the vertical axis representing the battery capacity (mAh) and the horizontal axis representing the number of cycles (times). From the figure, the battery BA of the present invention
While No. 1 retains the initial battery capacity (500 mAh) even after 400 cycles, the comparative battery BC1 has a sharp decrease in battery capacity from the beginning of the cycle, and the comparative battery BC1 has less than 250 mAh at 250 cycles. It can be seen that the battery capacity will decrease until.
【0024】叙上の実施例では本発明を円筒型電池に適
用する場合の具体例について説明したが、電池の形状に
特に制限はなく、本発明は扁平型、角型等、種々の形状
のリチウム二次電池に適用し得るものである。In the above embodiment, a specific example in which the present invention is applied to a cylindrical battery has been described, but the shape of the battery is not particularly limited, and the present invention has various shapes such as flat type and square type. It is applicable to a lithium secondary battery.
【0025】[0025]
【発明の効果】本発明電池においては、結着体シートか
らなる負極が使用されているので、サイクル特性に優れ
るなど、本発明は優れた特有の効果を奏する。In the battery of the present invention, since the negative electrode composed of the binder sheet is used, the present invention has excellent unique effects such as excellent cycle characteristics.
【図1】実施例で作製した負極の断面図である。FIG. 1 is a cross-sectional view of a negative electrode manufactured in an example.
【図2】円筒型の本発明電池BA1の断面図である。FIG. 2 is a sectional view of a cylindrical battery BA1 of the present invention.
【図3】サイクル特性図である。FIG. 3 is a cycle characteristic diagram.
【図4】従来電池の負極の断面図である。FIG. 4 is a cross-sectional view of a negative electrode of a conventional battery.
1 負極(結着体シート) 2 天然黒鉛粉末(リチウムを吸蔵放出可能な炭素粉
末) 3 ポリプロピレン樹脂(結着剤)1 Negative electrode (binder sheet) 2 Natural graphite powder (carbon powder capable of inserting and extracting lithium) 3 Polypropylene resin (binder)
───────────────────────────────────────────────────── フロントページの続き (72)発明者 森脇 和郎 大阪府守口市京阪本通2丁目18番地 三洋 電機株式会社内 (72)発明者 西尾 晃治 大阪府守口市京阪本通2丁目18番地 三洋 電機株式会社内 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuro Moriwaki 2-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Koji Nishio 2-18-2 Keihanhondori, Moriguchi-shi, Osaka Sanyo Denki Within the corporation
Claims (1)
を結着剤にて一体化してなる結着体シートからなること
を特徴とするリチウム二次電池。1. A lithium secondary battery, wherein the negative electrode comprises a binder sheet in which carbon powder capable of inserting and extracting lithium is integrated with a binder.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4116930A JPH05290837A (en) | 1992-04-09 | 1992-04-09 | Lithium secondary battery |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4116930A JPH05290837A (en) | 1992-04-09 | 1992-04-09 | Lithium secondary battery |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH05290837A true JPH05290837A (en) | 1993-11-05 |
Family
ID=14699216
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP4116930A Pending JPH05290837A (en) | 1992-04-09 | 1992-04-09 | Lithium secondary battery |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH05290837A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6048372A (en) * | 1997-09-29 | 2000-04-11 | Furukawa Denchi Kabushiki Kaisha | Method of producing an electrode plate used for a lithium secondary battery and a lithium secondary battery |
JP2006523374A (en) * | 2003-04-10 | 2006-10-12 | テキサコ オヴォニック バッテリー システムズ エルエルシー | Method for making an electrode for an electrochemical cell |
-
1992
- 1992-04-09 JP JP4116930A patent/JPH05290837A/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6048372A (en) * | 1997-09-29 | 2000-04-11 | Furukawa Denchi Kabushiki Kaisha | Method of producing an electrode plate used for a lithium secondary battery and a lithium secondary battery |
JP2006523374A (en) * | 2003-04-10 | 2006-10-12 | テキサコ オヴォニック バッテリー システムズ エルエルシー | Method for making an electrode for an electrochemical cell |
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