JPH10188937A - Nonaqueous electrolyte secondary battery - Google Patents
Nonaqueous electrolyte secondary batteryInfo
- Publication number
- JPH10188937A JPH10188937A JP8350892A JP35089296A JPH10188937A JP H10188937 A JPH10188937 A JP H10188937A JP 8350892 A JP8350892 A JP 8350892A JP 35089296 A JP35089296 A JP 35089296A JP H10188937 A JPH10188937 A JP H10188937A
- Authority
- JP
- Japan
- Prior art keywords
- separator
- aqueous electrolyte
- secondary battery
- electrolyte secondary
- battery
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、非水電解液二次電
池、さらに詳しくは安全性のすぐれた非水電解液二次電
池に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to a highly safe non-aqueous electrolyte secondary battery.
【０００２】[0002]
【従来の技術】負極としてリチウムやリチウム合金、炭
素材料のようなリチウムイオンのド―プ・脱ド―プが可
能な物質を使用し、正極としてリチウムコバルト複合酸
化物などのリチウム複合酸化物を使用した非水電解液二
次電池は、電池電圧が高く、高いエネルギ―密度を有す
るという特徴がある。このため、この種の二次電池は、
近年、ビデオ・カメラやラツプトツプ・パソコンなどの
消費電流の比較的大きな携帯用電子機器の供給電源とし
て、利用されている。2. Description of the Related Art A material capable of doping / de-doping lithium ions such as lithium, lithium alloy and carbon material is used as a negative electrode, and a lithium composite oxide such as a lithium cobalt composite oxide is used as a positive electrode. The used non-aqueous electrolyte secondary battery is characterized by a high battery voltage and a high energy density. For this reason, this type of secondary battery
In recent years, it has been used as a power supply for portable electronic devices that consume a relatively large amount of current, such as video cameras and laptop computers.
【０００３】ところで、電池を消費電流の大きな電子機
器に用いる場合、電極形式として、積層電極または巻回
電極体形式とするのが望ましい。たとえば、巻回電極体
は、帯状正極と帯状負極とを両者間にセパレ―タを介し
て渦巻状に巻回することにより作製されるが、このもの
は、電極面積が広くとれ、耐重負荷放電に耐えうるとい
う特徴がある。しかし、このような巻回電極体は、セパ
レ―タの幅と、帯状正極および帯状負極の幅を同一にす
ると、作製過程で上記正極および負極が高さ方向にずれ
たとき、上記正極および負極の一部がセパレ―タよりは
み出して互いに接触し、内部短絡を誘発するおそれがあ
る。[0003] When a battery is used in an electronic device that consumes a large amount of current, it is desirable to use a laminated electrode or a wound electrode body as an electrode type. For example, a spirally wound electrode body is manufactured by spirally winding a strip-shaped positive electrode and a strip-shaped negative electrode through a separator between them, and this has a large electrode area and can withstand heavy load discharge. There is a feature that can withstand. However, if the width of the separator is the same as the width of the strip-shaped positive electrode and the strip-shaped negative electrode, when the positive electrode and the negative electrode are displaced in the height direction in the manufacturing process, the wound electrode body has the above-mentioned structure. May protrude from the separator and come into contact with each other to cause an internal short circuit.
【０００４】このため、通常は、セパレ―タとして帯状
正極および帯状負極よりも幅の大きいものを用いて、積
層体を巻回した状態において、セパレ―タの上下両端が
上記正極および負極よりも上下にはみ出すような構成と
し、これによつて、上記正極および負極が上下に幾分ず
れても、セパレ―タを越えて接触するという不具合が生
じないように、余裕をもつた設計としている。[0004] For this reason, usually, a separator having a width larger than that of the band-shaped positive electrode and the band-shaped negative electrode is used, and when the laminate is wound, the upper and lower ends of the separator are larger than the positive electrode and the negative electrode. The structure is designed to protrude up and down, so that even if the positive electrode and the negative electrode are slightly displaced up and down, there is no problem in that a problem of contact beyond the separator occurs.
【０００５】[0005]
【発明が解決しようとする課題】しかし、このようにセ
パレ―タの上下両端が帯状正極および帯状負極より上下
にはみ出すような設計としても、これだけでは、二次電
池用充電装置が故障を起こして、二次電池が過充電状態
となつたとき、上記正極および負極とセパレ―タとの間
に上下方向に隙間があるために、巻回電極体の上下部に
デンドライト状のリチウムが堆積し、内部短絡を誘発す
るおそれがあつた。However, even with such a design that the upper and lower ends of the separator protrude above and below the band-shaped positive electrode and the band-shaped negative electrode, the charging device for the secondary battery may fail due to this alone. When the secondary battery is overcharged, dendritic lithium is deposited on the upper and lower portions of the wound electrode body because there is a gap in the vertical direction between the positive electrode and the negative electrode and the separator, There was a risk of causing an internal short circuit.
【０００６】また、セパレ―タの帯状正極および帯状負
極に接触する接触部分は、巻回圧力の加わつた圧力部を
構成しているのに対し、セパレ―タの上下両端のはみ出
し部分は、上記圧力がほとんどかからない非圧力部を構
成しており、過充電の場合、両部分の境界（電極エツジ
部）ないしその近傍において、とくにデンドライトが生
じやすい。このため、通常は、電池が過充電状態になら
ないように、安全回路などを用いて対策しているのが実
状である。さらに、このように巻回電極体の上下に堆積
したデンドライト状リチウムは、その多くが負極から遊
離して充放電に寄与しなくなるため、サイクル寿命の実
質的な低下につながる。Further, the contact portions of the separator contacting the strip-shaped positive electrode and the strip-shaped negative electrode constitute a pressure portion to which a winding pressure is applied, whereas the protruding portions at the upper and lower ends of the separator are formed as described above. It constitutes a non-pressure portion to which little pressure is applied, and in the case of overcharging, dendrites are particularly likely to occur at the boundary between both portions (electrode edge portion) or in the vicinity thereof. For this reason, in reality, measures are usually taken to prevent the battery from being overcharged by using a safety circuit or the like. Furthermore, most of the dendrite-like lithium deposited on and under the wound electrode body is released from the negative electrode and does not contribute to charging and discharging, which leads to a substantial reduction in cycle life.
【０００７】このような問題に対して、撥液性のセパレ
―タの一部の面に保液性を与える界面活性剤を塗布する
方法（特開平２−２８１５７４号公報）、セパレ―タの
はみ出し部分を加熱成形する方法（特開平７−１５３４
８８号公報）などが提案されている。しかし、これらの
方法は、工程が複雑で量産化が困難であり、コスト高の
要因となる。また、上記後者の方法は、電極内部のセパ
レ―タまでは熱が届きにくく、接触部分（圧力部）とは
み出し部分（非圧力部）との境界ないしその近傍でのデ
ンドライトの発生阻止には、効果が不十分である。To cope with such a problem, a method of applying a surfactant for imparting liquid retaining property to a part of the surface of a liquid repellent separator (Japanese Patent Laid-Open No. 2-281574) has been proposed. A method of heating and forming a protruding portion (Japanese Patent Laid-Open No. 7-1534)
No. 88) has been proposed. However, these methods have complicated steps, are difficult to mass-produce, and cause high costs. Further, in the latter method, heat hardly reaches the separator inside the electrode, and to prevent dendrite from being generated at the boundary between the contact portion (pressure portion) and the protruding portion (non-pressure portion) or in the vicinity thereof, The effect is insufficient.
【０００８】本発明は、上記の事情に照らし、電極体上
下部でのデンドライト状リチウムの析出がみられない、
安全性およびサイクル特性にすぐれ、しかも量産化可能
で低コストな非水電解液二次電池を提供することを目的
とする。According to the present invention, in view of the above circumstances, no precipitation of dendritic lithium at the upper and lower portions of the electrode body is observed.
It is an object of the present invention to provide a low-cost non-aqueous electrolyte secondary battery which is excellent in safety and cycle characteristics and can be mass-produced.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、上記の目
的に対する鋭意検討の過程において、セパレ―タとして
特定の微孔性フイルムを用い、これを帯状正極と帯状負
極との間に介装した電極体を筒状電池内に装填し、これ
に非水電解液を注入したときに、上記セパレ―タの上下
両端のはみ出し部分と正負両極に接触する接触部分との
間で、非水電解液の浸透による収縮応力差が生じて、両
部分の境界ないしその近傍において、セパレ―タを構成
する微孔性フイルムの微孔の少なくとも一部が閉孔され
たような状態となり、このような閉孔状態とすると、デ
ンドライト状リチウムの析出，堆積の阻止に好結果が得
られることを見い出した。Means for Solving the Problems In the course of intensive studies on the above object, the present inventors used a specific microporous film as a separator, and interposed this between a strip-shaped positive electrode and a strip-shaped negative electrode. When the non-aqueous electrolyte is injected into the cylindrical battery with the mounted electrode body, when the non-aqueous electrolyte is injected into the cylindrical battery, the non-aqueous liquid A difference in contraction stress due to the permeation of the electrolytic solution occurs, and at or near the boundary between the two portions, at least a portion of the micropores of the microporous film constituting the separator is closed. It has been found that when the pores are in a closed state, good results can be obtained in preventing precipitation and deposition of lithium dendrite.
【００１０】また、上記状態に加えて、上下両端のはみ
出し部分が筒状電池の内周側に曲折したような端部構造
となり、これが正負両極の短絡防止により好結果を与
え、しかも熱履歴を受けることなく、電解液の浸透作用
だけで上記微孔の閉孔さらには内周側への曲折が起こる
ために、電池作製の工程が簡単で量産化が可能であり、
また低コスト化にも寄与する、安全性およびサイクル特
性にすぐれ非水電解液二次電池が得られることを知り、
本発明を完成するに至つた。[0010] In addition to the above-mentioned state, an end structure in which the protruding portions at the upper and lower ends are bent toward the inner peripheral side of the cylindrical battery provides a good result by preventing the short circuit of the positive and negative electrodes, and furthermore, the heat history is improved. Without being affected, the pores are closed and even bent to the inner peripheral side only by the permeation of the electrolyte solution, so that the battery manufacturing process is simple and mass production is possible,
We also learned that a non-aqueous electrolyte secondary battery with excellent safety and cycle characteristics that contributes to cost reduction can be obtained.
The present invention has been completed.
【００１１】すなわち、本発明は、正極と負極とを両者
間に微孔性フイルムからなるセパレ―タを介して積層し
て用いる非水電解液二次電池において、セパレ―タの上
下両端が正極および負極より上下にはみ出しており、か
つこのはみ出し部分と正極および負極に接触する接触部
分との境界ないしその近傍の微孔の一部または全部が閉
孔されていることを特徴とする非水電解液二次電池（請
求項１）に係るものである。また、この二次電池におい
て、上記セパレ―タの構成として、平均細孔径が０．０
２〜０．１３μｍ、非水電解液収縮率が０．３〜５％の
微孔性フイルムからなり、上下両端のはみ出し部分が内
周側へ曲折されている構成（請求項２）、ポリエチレ
ン、ポリプロピレンまたはこれらの混合物を主構成成分
とする微孔性フイルムからなる構成（請求項３）を、好
ましい態様とする。That is, the present invention relates to a non-aqueous electrolyte secondary battery in which a positive electrode and a negative electrode are stacked and interposed therebetween via a separator made of a microporous film. And non-aqueous electrolysis characterized in that part or all of the micropores at or near the boundary between the protruding portion and the contact portion in contact with the positive electrode and the negative electrode are closed. The present invention relates to a liquid secondary battery (Claim 1). Further, in this secondary battery, the separator has an average pore diameter of 0.0
2 to 0.13 [mu] m, a non-aqueous electrolyte shrinkage ratio of 0.3 to 5%, made of a microporous film, a configuration in which the protruding portions at both upper and lower ends are bent inward (claim 2), polyethylene, A preferred embodiment is a structure comprising a microporous film containing polypropylene or a mixture thereof as a main component (Claim 3).
【００１２】[0012]
【発明の実施の形態】以下、本発明の実施の形態を、図
面を参考にして説明する。図１は、本発明の円筒型の非
水電解液二次電池の一例を示したものである。図におい
て、１は帯状正極、２は帯状負極であり、この両極１，
２を両者間に微孔性フイルムからなるセパレ―タ３を介
して積層して、渦巻状に巻回し、この巻回電極体を負極
端子を兼ねるステンレス鋼製の有底円筒状の電池ケ―ス
４内に装填し、これに非水電解液を注入した構成となつ
ている。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a cylindrical non-aqueous electrolyte secondary battery of the present invention. In the figure, 1 is a strip-shaped positive electrode, 2 is a strip-shaped negative electrode,
2 are laminated with a separator 3 made of a microporous film between the two, wound spirally, and the wound electrode body is a stainless steel bottomed cylindrical battery case also serving as a negative electrode terminal. In this configuration, a non-aqueous electrolytic solution is injected into the fuel cell 4.
【００１３】なお、図中、５，６は電池ケ―ス４の底部
および電極体上部に配置された絶縁体、７は環状パツキ
ングである。８は封口体であり、内部にＰＴＣ素子、セ
―フテイベント、電流遮断機構を備えている。In the drawings, reference numerals 5 and 6 denote insulators disposed on the bottom of the battery case 4 and the upper part of the electrode body, and reference numeral 7 denotes an annular packing. Reference numeral 8 denotes a sealing body, which has a PTC element, a safety event, and a current cutoff mechanism therein.
【００１４】帯状正極１としては、たとえば、リチウム
コバルト酸化物、リチウムニツケル酸化物、ＬｉＭｎ2
Ｏ4 、二酸化マンガン、五酸化バナジウム、クロム酸化
物などの金属酸化物、二硫化モリブデンなどの金属硫化
物が正極活物質として用いられ、これらの正極活物質に
対して導電助剤やポリテトラフルオロエチレンなどの結
着剤などを適宜添加した正極合剤を、アルミ箔などの集
電材料を芯材として帯状成形体に仕上げたものが用いら
れる。Examples of the band-shaped positive electrode 1 include lithium cobalt oxide, lithium nickel oxide, LiMn 2
Metal oxides such as O 4 , manganese dioxide, vanadium pentoxide, and chromium oxide, and metal sulfides such as molybdenum disulfide are used as the positive electrode active material. A positive electrode mixture to which a binder such as ethylene or the like is appropriately added, and which is formed into a belt-shaped molded body using a current collector material such as an aluminum foil as a core material is used.
【００１５】帯状負極２としては、アルカリ金属または
アルカリ金属を含む化合物を銅箔などの集電材料と一体
化したものが用いられる。アルカリ金属としては、たと
えば、リチウム、ナトリウム、カリウムなどが挙げられ
る。また、アルカリ金属を含む化合物としては、たとえ
ば、アルカリ金属とアルミニウム、鉛、インジウム、カ
リウム、カドミウム、スズ、マグネシウムなどの合金の
ほか、アルカリ金属と炭素材料との化合物、低電位のア
ルカリ金属と金属酸化物、硫化物との化合物などを挙げ
ることができる。As the band-shaped negative electrode 2, an electrode obtained by integrating an alkali metal or a compound containing an alkali metal with a current collecting material such as a copper foil is used. Examples of the alkali metal include lithium, sodium, and potassium. Examples of the compound containing an alkali metal include, for example, an alkali metal and an alloy of aluminum, lead, indium, potassium, cadmium, tin, magnesium, and the like, a compound of an alkali metal and a carbon material, and a low-potential alkali metal and a metal. Examples thereof include compounds with oxides and sulfides.
【００１６】帯状負極２としては、上記のほか、炭素材
料を用いてもよい。炭素材料は、リチウムイオンをド―
プ、脱ド―プできるものであればよく、たとえば、黒
鉛、熱分解炭素類、コ―クス類、ガラス状炭素類、有機
高分子化合物の焼成体、メソカ―ボンマイクロビ―ズ、
炭素繊維、活性炭などが用いられる。これらの炭素材料
は、（００２）面の面間距離ｄ002 が３．５Å以下、好
ましくは３．４５Å以下、より好ましくは３．４Å以下
であるのがよい。また、Ｃ軸方向の結晶子の大きさＬｃ
が３０Å以上、好ましくは８０Å以上、より好ましくは
２５０Å以上であるのがよい。さらに、平均粒径は８〜
２５μｍ、とくに１０〜１５μｍが好ましく、純度は９
９．９％以上であるのが好ましい。The strip-shaped negative electrode 2 may be made of a carbon material in addition to the above. Carbon materials dope lithium ions.
Any material can be used as long as it can be doped and de-doped, for example, graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, mesocarbon micro beads,
Carbon fiber, activated carbon and the like are used. These carbon materials have a (002) plane interplanar distance d 002 of 3.5 ° or less, preferably 3.45 ° or less, and more preferably 3.4 ° or less. Also, the crystallite size Lc in the C-axis direction
Is 30 ° or more, preferably 80 ° or more, and more preferably 250 ° or more. Furthermore, the average particle size is 8 to
25 μm, particularly preferably 10 to 15 μm, and the purity is 9
It is preferably at least 9.9%.
【００１７】セパレ―タ３は、平均細孔径が０．０２〜
０．１３μｍ、非水電解液収縮率が０．３〜５％の微孔
性フイルムから構成されている。平均細孔径が０．０２
μｍ以上となると、細孔が適度に大きくて電池での分極
が小さく、負極でのリチウム析出が起こりにくく、また
０．１３μｍ以下となると、孔径が適度に小さくて閉孔
が起こりやすく、後述する正負両極に挟まれた部分とは
み出し部分との境界ないしその近傍における孔内部での
デンドライト状リチウムの成長を抑制できる。非水電解
液収縮率が０．３％以上となると、収縮応力差が適度に
生じて円筒内周側への曲折性が増し、また５％以下とな
ると、極端な収縮が起きにくく、上下両端のはみ出し高
さが小さくても、内部短絡の防止に好結果が得られる。The separator 3 has an average pore diameter of 0.02 to 0.02.
It is composed of a microporous film having a nonaqueous electrolyte contraction rate of 0.3 to 5% and a nonaqueous electrolyte contraction rate of 0.3 to 5%. Average pore size of 0.02
When it is at least μm, the pores are moderately large and polarization in the battery is small, and lithium precipitation at the negative electrode is unlikely to occur, and when it is at or below 0.13 μm, the pore size is moderately small and pores are likely to occur, which will be described later. The growth of dendritic lithium inside the hole at or near the boundary between the portion sandwiched between the positive and negative electrodes and the protruding portion can be suppressed. When the non-aqueous electrolyte contraction rate is 0.3% or more, an appropriate contraction stress difference is generated to increase the bending property toward the inner circumferential side of the cylinder. Even if the protruding height is small, good results can be obtained in preventing an internal short circuit.
【００１８】なお、平均細孔径とは、走査型電子顕微鏡
による１万〜２．５万倍程度の拡大倍率で観察すること
により求められるもので、孔径の長軸および短軸を測定
し、平均長軸および平均短軸を相乗平均したものであ
る。また、非水電解液収縮率とは、２３〜２５℃の非水
電解液中にセパレ―タを浸漬し、２０時間放置後の寸法
変化を収縮前の寸法に対する百分率で表したものであ
る。The average pore diameter is determined by observing with a scanning electron microscope at a magnification of about 10,000 to 25,000 times, and the major axis and the minor axis of the pore diameter are measured. It is the geometric mean of the major axis and the average minor axis. The non-aqueous electrolyte shrinkage is a percentage change in dimensions after immersion of the separator in a non-aqueous electrolyte at 23 to 25 ° C. and left for 20 hours, relative to the dimensions before shrinkage.
【００１９】このようなセパレ―タ３としては、ポリエ
チレン、ポリプロピレンまたはこれらの混合物を主構成
成分としたものが好ましく、ポリブチレンなどの他のポ
リオレフイン系樹脂、ナイロン、セルロ―スアセテ―
ト、ポリアクリロニトリルなどを主構成成分としたもの
であつてもよい。これら主構成成分を用いた成形材料を
フイルム状に溶融押出したのち、延伸多孔質化し、さら
にエ―ジングする、とくに延伸方向に熱収縮させて寸法
安定性を付与する方法により、微孔性フイルムが得られ
る。その際、電解液収縮性の付与のために、熱収縮の度
合いはフイルム寸法が２〜１５％減少する程度とするの
が好ましい。The separator 3 is preferably one having polyethylene, polypropylene or a mixture thereof as a main component, and other polyolefin resins such as polybutylene, nylon and cellulose acetate.
And polyacrylonitrile as a main component. A molding material using these main components is melt-extruded into a film and then stretched and porous, followed by aging. In particular, heat shrinkage in the stretching direction to impart dimensional stability to the microporous film. Is obtained. At this time, in order to provide the electrolytic solution with shrinkability, the degree of heat shrinkage is preferably set to such an extent that the film size is reduced by 2 to 15%.
【００２０】上記の方法により微孔性フイルムを得るに
は、延伸に先立ち、フイルム状物を熱処理しておくのが
好ましい。熱処理は、加熱したロ―ルや金属板にフイル
ム状物を接触させる方法、フイルム状物を空気中や不活
性ガス中で加熱する方法、フイルム状物を芯体上に巻き
取り、このロ―ルを気相中で加熱する方法などを採用で
きる。熱処理温度は、１２０〜１７０℃に設定すること
ができる。また、熱処理時間は、熱処理の方法などに応
じて設定すればよく、とくに限定されないが、通常は約
２秒〜５０時間程度とするのがよい。In order to obtain a microporous film by the above method, it is preferable to heat-treat the film before stretching. Heat treatment can be performed by contacting the film with a heated roll or metal plate, heating the film in air or an inert gas, or winding the film on a core. For example, a method of heating the gas in the gas phase. The heat treatment temperature can be set at 120 to 170 ° C. The heat treatment time may be set according to the heat treatment method and the like, and is not particularly limited, but is usually preferably about 2 seconds to 50 hours.
【００２１】延伸多孔質化の方法は、とくに限定されな
い。気孔率を高くして電気抵抗の低い微孔性フイルムを
得るには、低温で延伸したのち、さらに高温で延伸する
多段延伸法を採用するのがよい。低温延伸は、通常−２
０℃〜６０℃の温度で行い、延伸率（Ｅ１％）が２０〜
２００％となるようにする。上記延伸率とは、低温延伸
前の寸法をＬ０、低温延伸後の寸法をＬ１とすると、Ｅ
１（％）＝〔（Ｌ１−Ｌ０）／Ｌ０〕×１００として、
求められる。また、高温延伸は、上記の低温延伸後、９
０〜１３０℃の温度で行い、延伸率（Ｅ２％）が１０〜
５００％となるようにする。上記延伸率とは、高温延伸
後の寸法をＬ２としたとき、Ｅ２（％）＝〔（Ｌ２−Ｌ
１）／Ｌ０〕×１００として、求められる。The method for making the film porous is not particularly limited. In order to increase the porosity and obtain a microporous film having a low electric resistance, it is preferable to employ a multi-stage stretching method in which the film is stretched at a low temperature and then further stretched at a high temperature. Low temperature stretching is usually -2
The stretching is performed at a temperature of 0 ° C to 60 ° C, and the stretching ratio (E1%) is 20 to
It should be 200%. The above-mentioned stretching ratio is defined as E0 when the dimension before low-temperature stretching is L0 and the dimension after low-temperature stretching is L1.
1 (%) = [(L1−L0) / L0] × 100,
Desired. In addition, high-temperature stretching is performed after the above-described low-temperature stretching.
The stretching is performed at a temperature of 0 to 130 ° C. and the stretching ratio (E2%) is 10 to 10.
Make it 500%. The above-mentioned stretching ratio is defined as E2 (%) = [(L2-L
1) / L0] × 100.
【００２２】このようにして作製される微孔性フイルム
は、単層構造だけでなく、多層構造とされていてもよ
い。厚さとしては、全厚が２０〜３０μｍの範囲内にあ
るのが望ましい。また、この微孔性フイルムには、老化
防止剤、充填剤、着色剤、帯電防止剤などの添加剤が適
宜含まれていてもよい。The microporous film produced in this way may have not only a single-layer structure but also a multilayer structure. It is desirable that the total thickness be in the range of 20 to 30 μm. In addition, the microporous film may appropriately contain additives such as an antioxidant, a filler, a coloring agent, and an antistatic agent.
【００２３】本発明では、上記の帯状正極１と帯状負極
２とを、上記の微孔性フイルムからなるセパレ―タ３を
介して積層して、渦巻状に巻回し、この巻回電極体を電
池ケ―ス４内に装填するが、その際、帯状正極１と帯状
負極２の幅がセパレ―タ３の幅より小さくなるように設
定しておくことにより、図２の拡大図に示すように、セ
パレ―タ３の上下両端が正負両極１，２より上下にはみ
出して、はみ出し部分３ａが生じるようにする。また、
上記電極体は、電池内に装填したときの電極面中央部の
巻回圧力が１Kg／cm2 以上であるとき、帯状正極１、帯
状負極２およびセパレ―タ３間に隙間ができにくく、セ
パレ―タ３に生じさせる収縮応力差を安定性よく起こさ
せるため、好ましい。In the present invention, the above-mentioned strip-shaped positive electrode 1 and strip-shaped negative electrode 2 are laminated via the separator 3 made of the above-mentioned microporous film, and are spirally wound. The battery case 4 is loaded into the battery case 4. At this time, the width of the band-shaped positive electrode 1 and the band-shaped negative electrode 2 is set to be smaller than the width of the separator 3 so as to be enlarged as shown in FIG. In addition, both upper and lower ends of the separator 3 protrude from the positive and negative poles 1 and 2 so that a protruding portion 3a is formed. Also,
When the winding pressure at the center of the electrode surface when loaded into the battery is 1 kg / cm 2 or more, a gap is hardly formed between the strip-shaped positive electrode 1, the strip-shaped negative electrode 2 and the separator 3, This is preferable because a difference in contraction stress caused in the heater 3 is generated with good stability.
【００２４】このように装填したうえで、これに非水電
解液を注入して、上記電極体に浸透させると、上記の微
孔性フイルムからなるセパレ―タ３は、帯状正極１およ
び帯状負極２に接触する接触部分３ｂ（圧力部）と、上
記のはみ出し部分３ａ（非圧力部）との収縮応力差によ
り、上記両部分３ａ，３ｂの境界（電極エツジ部）３ｃ
ないしその近傍において、微孔の一部または全部が閉孔
する。つまり、目詰りしたり、孔径が小さくなる。ま
た、これに伴い、セパレ―タの上記境界３ｃないしその
近傍が僅かに収縮して、はみ出し部分３ａは円筒内周側
へ自ら曲折し、正負両極１，２とセパレ―タ３間の上下
方向の隙間を閉じる。When the non-aqueous electrolytic solution is injected into the above-mentioned electrode body and is permeated into the electrode body, the separator 3 composed of the microporous film becomes a strip-shaped positive electrode 1 and a strip-shaped negative electrode. The boundary (electrode edge portion) 3c between the two portions 3a and 3b due to the difference in contraction stress between the contact portion 3b (pressure portion) contacting the portion 2 and the protruding portion 3a (non-pressure portion).
At or near the micropores, some or all of the micropores are closed. That is, clogging and a decrease in the hole diameter occur. Along with this, the boundary 3c of the separator or its vicinity slightly contracts, and the protruding portion 3a bends toward the inner peripheral side of the cylinder by itself, and the vertical direction between the positive and negative poles 1 and 2 and the separator 3 is increased. Close the gap.
【００２５】これらの作用により、上記境界３ｃないし
その近傍でのデンドライト状リチウムの成長による短絡
が抑制され、また電解液が存在しにくくなることによ
り、デンドライト状リチウムがセパレ―タが保持してい
る液中を成長しながら進んで、電極上下端部に堆積する
ことが阻止される。その結果、デンドライト状リチウム
の堆積がもたらす内部短絡ブリツジの形成が防がれ、ま
た充放電に寄与しうるリチウムイオン量の減少が防がれ
ることになり、結局、煩雑な工程を要することなく、安
全性およびサイクル特性にすぐれ、しかも量産化可能で
低コストである実用性にすぐれた非水電解液二次電池が
得られることになる。By these actions, the short circuit due to the growth of dendritic lithium at or near the boundary 3c is suppressed, and the separator is held by the dendritic lithium by making it difficult for the electrolyte to be present. It is prevented from proceeding while growing in the liquid and depositing on the upper and lower ends of the electrode. As a result, the formation of an internal short-circuit bridge caused by the deposition of dendritic lithium is prevented, and a reduction in the amount of lithium ions that can contribute to charging and discharging is prevented.In the end, without requiring a complicated process, A non-aqueous electrolyte secondary battery which is excellent in safety and cycle characteristics, can be mass-produced, and is low in cost and excellent in practical use can be obtained.
【００２６】上記の非水電解液としては、たとえば、リ
チウム塩を電解質とし、これを有機溶媒に溶解した電解
液が用いられる。有機溶媒としては、とくに限定され
ず、たとえば、プロピレンカ―ボネ―ト、エチレンカ―
ボネ―ト、ブチレンカ―ボネ―ト、γ−ブチロラクト
ン、γ−バレロラクトン、ジメチルカ―ボネ―ト、プロ
ピオン酸メチル、酢酸エチルなどのエステル類、アセト
ニトリルなどのニトニル類、１，２−ジメトキシエタ
ン、１，２−ジメトキシメタン、ジメトキシプロパン、
１，３−ジオキソラン、テトラヒドロフラン、２−メチ
ルテトラヒドロフラン、４−メチル−１，３−ジオキソ
ランなどのエ―テル類、スルフオランなどの１種または
２種類以上の混合溶媒が挙げられる。As the non-aqueous electrolyte, for example, an electrolyte obtained by dissolving a lithium salt in an organic solvent is used. The organic solvent is not particularly limited. For example, propylene carbonate, ethylene carbonate
Carbonate, butylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl carbonate, methyl propionate, esters such as ethyl acetate, nitroniles such as acetonitrile, 1,2-dimethoxyethane, , 2-dimethoxymethane, dimethoxypropane,
Ethers such as 1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 4-methyl-1,3-dioxolane, and one or more kinds of mixed solvents such as sulfolane.
【００２７】また、電解質としては、たとえば、ＬｉＣ
ｌＯ4 、ＬｉＰＦ6 、ＬｉＢＦ4 、ＬｉＡｓＦ6 、Ｌｉ
ＳｂＦ6 、ＬｉＣＦ3 ＳＯ3 、ＬｉＣ4 Ｆ9 ＳＯ3 、Ｌ
ｉＣＦ3 ＣＯ2 、Ｌｉ2 Ｃ2 Ｆ4 （ＳＯ3 ）2 、ＬｉＮ
（ＣＦ3 ＳＯ2 ）2 、ＬｉＣ（ＣＦ3 ＳＯ2 ）3 、Ｌｉ
Ｃn Ｆ2n+1ＳＯ3 （ｎ≧２）などの１種または２種以上
の混合物が用いられる。非水電解液中における電解質の
濃度としては、とくに限定されないが、通常は、０．３
〜１．７モル／リツトル、好ましくは０．４〜１．５モ
ル／リツトルとなるようにするのがよい。As the electrolyte, for example, LiC
10 4 , LiPF 6 , LiBF 4 , LiAsF 6 , Li
SbF 6 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , L
iCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN
(CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , Li
One or a mixture of two or more such as C n F 2n + 1 SO 3 (n ≧ 2) is used. The concentration of the electrolyte in the non-aqueous electrolyte is not particularly limited, but is usually 0.3
It is good to be set to 1.7 mol / liter, preferably 0.4 to 1.5 mol / liter.
【００２８】なお、上記の例では、セパレ―タ３として
特定の平均細孔径および非水電解液収縮率を有する微孔
性フイルムを用い、非水電解液の浸透によるはみ出し部
分３ａと接触部分３ｂとの収縮応力差を利用して、境界
３ｃないしその近傍の微孔の一部または全部を閉孔させ
るようにしたものであるが、他の加熱成形法（特開平７
−１５３４８８号公報）などでは最も重要なエツジ部近
傍の閉孔が不十分になつてしまう。また、上記の閉孔手
段によると、同時にはみ出し部分３ａを円筒内周側へ曲
折する構造とすることができ、これにより電池の安全性
などに好結果が得られるため、好ましい。In the above example, a microporous film having a specific average pore diameter and a non-aqueous electrolyte contraction rate is used as the separator 3, and the protruding portion 3a and the contact portion 3b due to the penetration of the non-aqueous electrolyte are used. A part or all of the micropores in or near the boundary 3c is closed by utilizing the difference in shrinkage stress between the heat-forming method and the other heat-forming method (Japanese Unexamined Patent Publication No.
In the case of Japanese Patent Application Laid-Open No. 153488/1993, the hole near the most important edge portion becomes insufficient. Further, according to the above-mentioned closing means, it is possible to simultaneously bend the protruding portion 3a to the inner peripheral side of the cylinder, thereby obtaining good results in terms of battery safety and the like, which is preferable.
【００２９】[0029]
【実施例】以下、本発明の実施例を記載して、より具体
的に説明する。EXAMPLES Examples of the present invention will be described below in more detail.
【００３０】実施例１ ＬｉＣｏＯ2 に導電助剤としてリン状黒鉛を重量比９
０：５で加えて混合し、この混合物と、ポリフツ化ビニ
リデンをＮ−メチルピロリドンに溶解させた溶液とを混
合してスラリ―にした。この正極合剤スラリ―を７０メ
ツシユの網を通過させて大きなものを取り除いたのち、
厚さが２０μｍのアルミニウム箔からなる正極集電体の
両面に均一に塗布して乾燥し、その後、ロ―ラプレス機
により圧縮形成したのち、切断し、リ―ド体を溶接し
て、帯状正極とした。EXAMPLE 1 Phosphorous graphite was added to LiCoO 2 as a conductive additive at a weight ratio of 9
The mixture was added and mixed at 0: 5, and the mixture was mixed with a solution of polyvinylidene fluoride in N-methylpyrrolidone to form a slurry. After passing this positive electrode mixture slurry through a 70 mesh net to remove large ones,
A positive electrode current collector made of an aluminum foil having a thickness of 20 μm is uniformly coated on both sides and dried, then pressed and formed by a roller press machine, cut, and a lead body is welded to form a belt-shaped positive electrode. And
【００３１】炭素材料（ｄ002 ＝３．３７Å、Ｌｃ＝９
５０Å、平均粒径１０μｍ、純度９９．９％以上）を、
フツ化ビニリデンをＮ−メチルピロリドンに溶解させた
溶液と混合してスラリ―にした。この負極合剤スラリ―
を７０メツシユの網を通過させて大きなものを取り除い
たのち、厚さが１８μｍの帯状の銅箔からなる負極集電
体の両面に均一に塗布して乾燥し、その後、ロ―ラプレ
ス機により圧縮成形したのち、切断し、リ―ド体を溶接
して、帯状負極とした。Carbon material (d 002 = 3.37 °, Lc = 9
50 °, average particle size 10 μm, purity 99.9% or more)
It was mixed with a solution of vinylidene fluoride in N-methylpyrrolidone to form a slurry. This negative mix slurry
After passing through a mesh of 70 mesh to remove large pieces, apply uniformly on both sides of a negative electrode current collector made of a strip-shaped copper foil having a thickness of 18 μm, dry and compress with a roller press. After being formed, it was cut and the lead body was welded to obtain a strip-shaped negative electrode.
【００３２】外層にポリプロピレン層、内層にポリエチ
レンとポリプロピレンとの混合層を有する全厚が２７μ
ｍの多層構造の微孔性フイルムからなり、フイルム作製
段階での熱収縮を調整して、平均細孔径が０．０７μ
ｍ、非水電解液収縮率が０．７％である微孔性フイルム
を得、これをセパレ―タとした。The outer layer has a polypropylene layer and the inner layer has a mixed layer of polyethylene and polypropylene.
m, having a multi-layered microporous film having an average pore diameter of 0.07 μm by adjusting heat shrinkage in the film production stage.
m, a microporous film having a nonaqueous electrolyte shrinkage of 0.7% was obtained, and this was used as a separator.
【００３３】つぎに、前記の帯状正極と帯状負極とを、
上記のセパレ―タを介して互いに重なるように、渦巻状
に巻回して、巻回電極体とし、これを外径が１８mmの有
底円筒状の電池ケ―ス内に充填し、正極および負極のリ
―ド体の溶接を行つた。この電池ケ―ス内に、電解液と
してエチレンカ―ボネ―ト１容量部とメチルエチルカ―
ボネ―ト２容量部との混合溶媒中にＬｉＰＦ6 を１．４
モル／リツトルの割合で溶解してなる非水電解液を注入
し、非水電解液がセパレ―タなどに十分に浸透したの
ち、封口することにより、図１に示す構造の円筒型の非
水電解液二次電池を作製した。Next, the strip-shaped positive electrode and the strip-shaped negative electrode were
A spirally wound electrode body is formed so as to overlap with each other via the separator described above to form a wound electrode body, which is filled in a bottomed cylindrical battery case having an outer diameter of 18 mm, and a positive electrode and a negative electrode are provided. Of the lead body was welded. In this battery case, 1 volume part of ethylene carbonate and methyl ethyl
LiPF 6 in a mixed solvent with 2 parts by volume of boron was 1.4.
A non-aqueous electrolytic solution dissolved at a mole / liter ratio is injected, and after the non-aqueous electrolytic solution has sufficiently penetrated into a separator or the like, the cylindrical non-aqueous solution having the structure shown in FIG. An electrolyte secondary battery was manufactured.
【００３４】この非水電解液二次電池について、電池作
製後１０時間放置したのち、電池上端部を切断し、巻回
電極体を取り出したところ、巻回電極体の上下端部のセ
パレ―タのはみ出し部分は内周側へ曲折していた。ま
た、巻回電極体の巻回圧力は、富士フイルム（株）製の
プレスケ―ル圧力センサ―を別途挿入した別の円筒型の
非水電解液二次電池を分解し、確認したところ、約４Kg
／cm2 であつた。After the non-aqueous electrolyte secondary battery was allowed to stand for 10 hours after its production, the upper end of the battery was cut off and the wound electrode body was taken out. The protruding part was bent inward. The winding pressure of the wound electrode body was determined by disassembling another cylindrical non-aqueous electrolyte secondary battery into which a press scale pressure sensor manufactured by FUJIFILM Corporation was separately inserted. 4kg
/ Cm 2 .
【００３５】さらに、走査型電子顕微鏡（倍率１０，０
００倍）を用いた観察により、セパレ―タにおける正負
両極に接触する接触部分（圧力部）と上下両端のはみ出
し部分（非圧力部）は、電池ケ―ス内への充填前と変わ
らない孔径を保持していたが、上記接触部分とはみ出し
部分との境界ないしその近傍は、微孔の一部または全部
が電池ケ―ス内への充填前に比べて閉孔していることが
確認された。ちなみに、図３は上記境界ないしその近傍
の微孔の構造を示す走査型電子顕微鏡写真、図４は上記
接触部分の微孔の構造を示す走査型電子顕微鏡写真、図
５は上記はみ出し部分の微孔の構造を示す走査型電子顕
微鏡写真、である。Further, a scanning electron microscope (magnification: 10,0)
According to the observation using a magnification of × 00, the contact part (pressure part) in contact with the positive and negative electrodes and the protruding parts at both upper and lower ends (non-pressure part) of the separator have the same hole diameter as before filling the battery case. However, it was confirmed that some or all of the micropores were closed at or near the boundary between the contact portion and the protruding portion as compared to before the filling into the battery case. Was. FIG. 3 is a scanning electron micrograph showing the structure of the pores at or near the boundary, FIG. 4 is a scanning electron micrograph showing the structure of the pores at the contact portion, and FIG. 5 is a micrograph of the protruding portion. 4 is a scanning electron micrograph showing the structure of a hole.
【００３６】実施例２ 外層にポリプロピレン層、内層にポリエチレンとポリプ
ロピレンとの混合層を有する全厚が２８μｍの多層構造
の微孔性フイルムからなり、フイルム作製段階での熱収
縮を調整して、平均細孔径が０．０８μｍ、非水電解液
収縮率が０．３％である微孔性フイルムを得た。これを
セパレ―タとした以外は、実施例１と同様にして、円筒
型の非水電解液二次電池を作製した。Example 2 A multilayer microporous film having a total thickness of 28 μm and having a polypropylene layer as an outer layer and a mixed layer of polyethylene and polypropylene as an inner layer was prepared. A microporous film having a pore size of 0.08 μm and a nonaqueous electrolyte shrinkage of 0.3% was obtained. A cylindrical non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this was used as a separator.
【００３７】この非水電解液二次電池について、電池作
製後１０時間放置したのち、電池上下の端部を切断し、
巻回電極体を取り出したところ、巻回電極体の上下端部
のセパレ―タのはみ出し部分は内周側へ曲折していた。
また、実施例１と同様にして巻回電極体の巻回圧力を調
べたところ、約４Kg／cm2 であつた。さらに、走査型電
子顕微鏡により、セパレ―タにおける正負両極に接触す
る接触部分と上下両端のはみ出し部分は、電池ケ―ス内
への充填前と変わらない孔径を保持していたが、上記接
触部分とはみ出し部分との境界ないしその近傍は、微孔
の一部または全部が電池ケ―ス内への充填前に比べて閉
孔していることが確認された。After leaving the non-aqueous electrolyte secondary battery for 10 hours after the production of the battery, the upper and lower ends of the battery were cut off.
When the wound electrode body was taken out, the protruding portions of the separators at the upper and lower ends of the wound electrode body were bent inward.
Further, when the winding pressure of the wound electrode body was examined in the same manner as in Example 1, the result was about 4 kg / cm 2 . Furthermore, according to the scanning electron microscope, the contact portion in contact with the positive and negative electrodes and the protruding portions at the upper and lower ends of the separator maintained the same hole diameter as before filling into the battery case. It was confirmed that at or near the boundary with the protruding portion, some or all of the micropores were closed as compared to before the filling into the battery case.
【００３８】実施例３ 外層にポリプロピレン層、内層にポリエチレン層を有す
る全厚が２６μｍの多層構造の微孔性フイルムからな
り、フイルム作製段階での熱収縮を調整して、平均細孔
径が０．１１μｍ、非水電解液収縮率が４．５％である
微孔性フイルムを得た。これをセパレ―タとした以外
は、実施例１と同様にして、円筒型の非水電解液二次電
池を作製した。Example 3 A multi-layered microporous film having a total thickness of 26 μm and having a polypropylene layer as an outer layer and a polyethylene layer as an inner layer was prepared. A microporous film having a thickness of 11 μm and a nonaqueous electrolyte contraction rate of 4.5% was obtained. A cylindrical non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this was used as a separator.
【００３９】この非水電解液二次電池について、電池作
製後１０時間放置したのち、電池上端部を切断し、巻回
電極体を取り出したところ、巻回電極体の上下端部のセ
パレ―タのはみ出し部分は内周側へ曲折していた。ま
た、実施例１と同様にして巻回電極体の巻回圧力を調べ
たところ、約２Kg／cm2 であつた。さらに、走査型電子
顕微鏡により、セパレ―タにおける正負両極に接触する
接触部分と上下両端のはみ出し部分は、電池ケ―ス内へ
の充填前と変わらない孔径を保持していたが、上記接触
部分とはみ出し部分との境界ないしその近傍は、微孔の
一部または全部が電池ケ―ス内への充填前に比べて閉孔
していることが確認された。After leaving the non-aqueous electrolyte secondary battery for 10 hours after its production, the upper end of the battery was cut off, and the wound electrode assembly was taken out. The protruding part was bent inward. Further, when the winding pressure of the wound electrode body was examined in the same manner as in Example 1, it was found to be about 2 kg / cm 2 . Furthermore, according to the scanning electron microscope, the contact portion in contact with the positive and negative electrodes and the protruding portions at the upper and lower ends of the separator maintained the same hole diameter as before filling into the battery case. It was confirmed that at or near the boundary with the protruding portion, some or all of the micropores were closed as compared to before the filling into the battery case.
【００４０】実施例４ ポリエチレンの単層構造からなる厚さが２５μｍの微孔
性フイルムからなり、フイルム作製段階での熱収縮を調
整して、平均細孔径が０．０２μｍ、非水電解液収縮率
が２．３％である微孔性フイルムを得た。これをセパレ
―タとした以外は、実施例１と同様にして、円筒型の非
水電解液二次電池を作製した。Example 4 A microporous film having a single-layer structure of polyethylene and having a thickness of 25 μm was prepared. By adjusting the heat shrinkage in the film production stage, the average pore diameter was 0.02 μm, and the non-aqueous electrolyte shrinkage. A microporous film having a ratio of 2.3% was obtained. A cylindrical non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this was used as a separator.
【００４１】この非水電解液二次電池について、電池作
製後１０時間放置したのち、電池上端部を切断し、巻回
電極体を取り出したところ、巻回電極体の上下端部のセ
パレ―タのはみ出し部分は内周側へ曲折していた。ま
た、実施例１と同様にして巻回電極体の巻回圧力を調べ
たところ、約１Kg／cm2 であつた。さらに、走査型電子
顕微鏡により、セパレ―タにおける正負両極に接触する
接触部分と上下両端のはみ出し部分は、電池ケ―ス内へ
の充填前と変わらない孔径を保持していたが、上記接触
部分とはみ出し部分との境界ないしその近傍は、微孔の
一部または全部が電池ケ―ス内への充填前に比べて閉孔
していることが確認された。After leaving the non-aqueous electrolyte secondary battery for 10 hours after the production of the battery, the upper end of the battery was cut off and the wound electrode body was taken out, and the upper and lower ends of the wound electrode body were separated. The protruding part was bent inward. Further, when the winding pressure of the wound electrode body was examined in the same manner as in Example 1, it was found to be about 1 kg / cm 2 . Furthermore, according to the scanning electron microscope, the contact portion in contact with the positive and negative electrodes and the protruding portions at the upper and lower ends of the separator maintained the same hole diameter as before filling into the battery case. It was confirmed that at or near the boundary with the protruding portion, some or all of the micropores were closed as compared to before the filling into the battery case.
【００４２】比較例１ ポリエチレンの単層構造からなる厚さが２６μｍの微孔
性フイルムからなり、フイルム作製段階での熱収縮を調
整して、平均細孔径が０．０９μｍ、非水電解液収縮率
が０．１％である微孔性フイルムを得た。これをセパレ
―タとした以外は、実施例１と同様にして、円筒型の非
水電解液二次電池を作製した。COMPARATIVE EXAMPLE 1 A microporous film having a single-layer structure of polyethylene and having a thickness of 26 μm was prepared. By adjusting the heat shrinkage in the film production stage, the average pore diameter was 0.09 μm, and the non-aqueous electrolyte contracted. A microporous film having a percentage of 0.1% was obtained. A cylindrical non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this was used as a separator.
【００４３】この非水電解液二次電池について、電池作
製後１０時間放置したのち、電池上端部を切断し、巻回
電極体を取り出したところ、巻回電極体の上下端部のセ
パレ―タのはみ出し部分は内周側へ曲折していなかつ
た。また、実施例１と同様にして巻回電極体の巻回圧力
を調べたところ、約２Kg／cm2 であつた。さらに、走査
型電子顕微鏡により、セパレ―タの正負両極に接触する
接触部分と上下両端のはみ出し部分との境界ないしその
近傍は、上記接触部分およびはみ出し部分と同様に、電
池ケ―ス内への充填前とほとんど変わらない孔径を保持
していた。After leaving the non-aqueous electrolyte secondary battery for 10 hours after the battery was prepared, the upper end of the battery was cut off and the wound electrode body was taken out. The protruding part was not bent inward. Further, when the winding pressure of the wound electrode body was examined in the same manner as in Example 1, it was found to be about 2 kg / cm 2 . Further, by using a scanning electron microscope, the boundary between or near the contact portion that contacts the positive and negative poles of the separator and the protruding portions at the upper and lower ends, as well as the above-mentioned contact portion and protruding portion, is inserted into the battery case. The pore diameter was almost the same as before filling.
【００４４】比較例２ ポリエチレンの単層構造からなる厚さが２７μｍの微孔
性フイルムからなり、フイルム作製段階での熱収縮を調
整して、平均細孔径が０．１４μｍ、非水電解液収縮率
が０．５％である微孔性フイルムを得た。これをセパレ
―タとした以外は、実施例１と同様にして、円筒型の非
水電解液二次電池を作製した。COMPARATIVE EXAMPLE 2 A microporous film having a single-layer structure of polyethylene and having a thickness of 27 μm was prepared. By adjusting the heat shrinkage in the film production stage, the average pore diameter was 0.14 μm, and the non-aqueous electrolyte shrinkage. A microporous film having a ratio of 0.5% was obtained. A cylindrical non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that this was used as a separator.
【００４５】この非水電解液二次電池について、電池作
製後１０時間放置したのち、電池上端部を切断し、巻回
電極体を取り出したところ、巻回電極体の上下端部のセ
パレ―タのはみ出し部分は内周側へ曲折していなかつ
た。また、実施例１と同様にして巻回電極体の巻回圧力
を調べたところ、約２Kg／cm2 であつた。さらに、走査
型電子顕微鏡による観察で、セパレ―タの正負両極に接
触する接触部分と上下両端のはみ出し部分との境界ない
しその近傍は、上記接触部分およびはみ出し部分に比べ
れば、孔径の変化が多少認められたが、この変化は電池
ケ―ス内への充填前に比べてそれほど顕著なものではな
かつた。After leaving the non-aqueous electrolyte secondary battery for 10 hours after producing the battery, the upper end of the battery was cut off, and the wound electrode body was taken out. The protruding part was not bent inward. Further, when the winding pressure of the wound electrode body was examined in the same manner as in Example 1, it was found to be about 2 kg / cm 2 . Further, when observed by a scanning electron microscope, the boundary between the contact portion that contacts the positive and negative poles of the separator and the protruding portions at the upper and lower ends or in the vicinity thereof has a slight change in the hole diameter as compared with the contact portion and the protruding portion. Although observed, this change was less pronounced than before filling into the battery case.
【００４６】以上の実施例１〜４および比較例１，２に
準じた方法で、別途、各非水電解液二次電池を作製し、
それぞれについて、上限電圧４．１Ｖで０．２Ｃ定電流
充電を５時間行い、この充電状態のまま３０℃条件下、
２４時間保存した。ついで、２．６Ａ定電流充電を２０
分間行い、過充電状態での二次電池内部の巻回電極体の
上下端部を観察した。結果は、表１に示されるとおりで
あつた。Separately, each non-aqueous electrolyte secondary battery was manufactured in the same manner as in Examples 1 to 4 and Comparative Examples 1 and 2,
For each of them, a constant current charge of 0.2 C was performed at an upper limit voltage of 4.1 V for 5 hours.
Stored for 24 hours. Then, 2.6A constant current charging was performed for 20 times.
After that, the upper and lower ends of the wound electrode body inside the secondary battery in the overcharged state were observed. The results were as shown in Table 1.
【００４７】 [0047]
【００４８】上記の表１の結果から明らかなように、比
較例１，２の非水電解液二次電池では、巻回電極体上下
端部のデンドライト状リチウムの析出がみられたのに対
し、本発明の実施例１〜４の非水電解液二次電池では、
上記析出が全く認められず、本発明により、特別な工程
を要することなく、安全性およびサイクル特性にすぐれ
た非水電解液二次電池を製造できるものであることがわ
かる。As is clear from the results shown in Table 1 above, in the nonaqueous electrolyte secondary batteries of Comparative Examples 1 and 2, precipitation of dendritic lithium at the upper and lower ends of the wound electrode body was observed. In the non-aqueous electrolyte secondary batteries of Examples 1 to 4 of the present invention,
The above-mentioned precipitation is not recognized at all, and it is understood that the present invention can produce a nonaqueous electrolyte secondary battery excellent in safety and cycle characteristics without requiring a special step.
【００４９】[0049]
【発明の効果】以上のように、本発明によれば、微孔性
フイルムからなる特定構成のセパレ―タを用いることに
より、電極体上下部でのデンドライト状リチウムの析出
がみられない、安全性およびサイクル特性にすぐれ、し
かも量産化可能で低コストな非水電解液二次電池を提供
することができる。As described above, according to the present invention, the use of a separator having a specific structure composed of a microporous film prevents the deposition of dendrite-like lithium at the upper and lower portions of the electrode body. It is possible to provide a low-cost non-aqueous electrolyte secondary battery which is excellent in performance and cycle characteristics and can be mass-produced.
【図１】本発明の非水電解液二次電池の一例を示す断面
図である。FIG. 1 is a sectional view showing an example of a non-aqueous electrolyte secondary battery of the present invention.
【図２】図１のII部分を拡大して示す断面図である。FIG. 2 is an enlarged sectional view showing a portion II in FIG. 1;
【図３】実施例１の非水電解液二次電池を構成するセパ
レ―タの正負両極に接触する接触部分と上下両端のはみ
出し部分との境界ないしその近傍の微孔の構造を示す走
査型電子顕微鏡写真（倍率１０，０００倍）である。FIG. 3 is a scanning type diagram showing the structure of the micropores at the boundary between the contact portions of the separator constituting the non-aqueous electrolyte secondary battery of Example 1 which are in contact with the positive and negative electrodes and the protruding portions at the upper and lower ends or in the vicinity thereof. It is an electron micrograph (magnification 10,000 times).
【図４】実施例１の非水電解液二次電池を構成するセパ
レ―タの正負両極に接触する接触部分を示す走査型電子
顕微鏡写真（倍率１０，０００倍）である。FIG. 4 is a scanning electron micrograph (magnification: 10,000 times) showing a contact portion of the separator constituting the non-aqueous electrolyte secondary battery of Example 1 which contacts the positive and negative electrodes.
【図５】実施例１の非水電解液二次電池を構成するセパ
レ―タの上下両端のはみ出し部分の微孔の構造を示す走
査型電子顕微鏡写真（倍率１０，０００倍）である。FIG. 5 is a scanning electron micrograph (magnification: 10,000 times) showing the structure of micropores at the upper and lower ends of the separator constituting the nonaqueous electrolyte secondary battery of Example 1.
１ 正極 ２ 負極 ３ セパレ―タ ３ａ セパレ―タの上下両端のはみ出し部分 ３ｂ セパレ―タの正負両極への接触部分 ３ｃ 上記はみ出し部分と接触部分との境界 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 3a Protruding portions at both upper and lower ends of separator 3b Contact portions of positive and negative electrodes of separator 3c Boundary between protruding portion and contact portion
Claims (3)
からなるセパレ―タを介して積層して用いる非水電解液
二次電池において、セパレ―タの上下両端が正極および
負極より上下にはみ出しており、かつこのはみ出し部分
と正極および負極に接触する接触部分との境界ないしそ
の近傍の微孔の一部または全部が閉孔されていることを
特徴とする非水電解液二次電池1. A non-aqueous electrolyte secondary battery in which a positive electrode and a negative electrode are stacked with a microporous film separator interposed therebetween, wherein both upper and lower ends of the separator are vertically above and below the positive electrode and the negative electrode. A non-aqueous electrolyte secondary battery characterized in that part or all of the micropores protruding from the protruding portion and the contact portion in contact with the positive electrode and the negative electrode or the vicinity thereof are closed.
０．１３μｍ、非水電解液収縮率が０．３〜５％の微孔
性フイルムからなり、上下両端のはみ出し部分が内周側
へ曲折されている請求項１に記載の非水電解液二次電
池。2. The separator has an average pore size of 0.02 to 0.02.
2. The non-aqueous electrolyte solution according to claim 1, wherein the non-aqueous electrolyte solution is made of a microporous film having a non-aqueous electrolyte shrinkage of 0.3 to 5% and the protruding portions at both upper and lower ends are bent inward. Next battery.
ピレンまたはこれらの混合物を主構成成分とする微孔性
フイルムからなる請求項１または２に記載の非水電解液
二次電池3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the separator comprises a microporous film containing polyethylene, polypropylene or a mixture thereof as a main component.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35089296A JP3805452B2 (en) | 1996-12-27 | 1996-12-27 | Method for producing non-aqueous electrolyte secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35089296A JP3805452B2 (en) | 1996-12-27 | 1996-12-27 | Method for producing non-aqueous electrolyte secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10188937A true JPH10188937A (en) | 1998-07-21 |
| JP3805452B2 JP3805452B2 (en) | 2006-08-02 |
Family
ID=18413610
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP35089296A Expired - Fee Related JP3805452B2 (en) | 1996-12-27 | 1996-12-27 | Method for producing non-aqueous electrolyte secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3805452B2 (en) |
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| JP2001085000A (en) * | 1999-09-14 | 2001-03-30 | At Battery:Kk | Thin battery and manufacturing method therefor |
| KR20060118955A (en) * | 2005-05-18 | 2006-11-24 | 삼성에스디아이 주식회사 | Jelly-roll type electrode assembly and li secondary battery with the same |
| JP2007134149A (en) * | 2005-11-10 | 2007-05-31 | Sony Corp | Nonaqueous electrolyte battery |
| KR100948972B1 (en) | 2005-11-03 | 2010-03-23 | 주식회사 엘지화학 | Secondary Battery Employed with Partially Folded Separator |
| KR101107075B1 (en) * | 2009-10-28 | 2012-01-20 | 삼성에스디아이 주식회사 | Rechargeable battery |
| US11942603B2 (en) | 2018-08-13 | 2024-03-26 | Lg Energy Solution, Ltd. | Stack-folding type electrode assembly and lithium metal battery including the same |
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| US11942603B2 (en) | 2018-08-13 | 2024-03-26 | Lg Energy Solution, Ltd. | Stack-folding type electrode assembly and lithium metal battery including the same |
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