JP4403698B2 - Winding battery manufacturing method - Google Patents
Winding battery manufacturing method Download PDFInfo
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- JP4403698B2 JP4403698B2 JP2002364874A JP2002364874A JP4403698B2 JP 4403698 B2 JP4403698 B2 JP 4403698B2 JP 2002364874 A JP2002364874 A JP 2002364874A JP 2002364874 A JP2002364874 A JP 2002364874A JP 4403698 B2 JP4403698 B2 JP 4403698B2
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- battery
- separator
- electrode
- wound
- positive electrode
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- 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
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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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Description
【0001】
【発明の属する技術分野】
本発明は電池の製造法に関し、特にその電極群の捲回工程に関する。
【0002】
【従来の技術】
近年、電子機器のポータブル化、コードレス化が急速に進行している。その中で、特に普及の著しいノートパソコン、携帯電話、AV機器の電源には、従来の水溶液系二次電池(ニッケルカドミウム蓄電池、ニッケル水素蓄電池)や、より小型・軽量・高エネルギー密度なリチウムイオン二次電池などの小型二次電池が主に採用されている。
【0003】
そして機器の携帯性と多様化が増加する中、さらなる信頼性向上が小型二次電池には必要である。幾つかの課題があるが、特にその中でも、電池への異常な衝撃や異常な加熱によってセパレータが正極と負極との隔離を保てず、短絡箇所でジュール熱が発生するという課題があった。
【0004】
セパレータは機械的かつ熱的に十分な強度を持って正極と負極の隔離を維持する機能が求められている。例えば、リチウムイオン二次電池に用いられているセパレータは一般的にポリエチレンやポリプロピレン製の微多孔膜であり、特に膜にテンションが掛かっていない限り加熱によって容易かつ大幅に収縮するという問題があった。
【0005】
従来から、電池内の内部短絡を防ぐために、セパレータを溶着して極板を包むように構成する方法が提案されている。(例えば、特許文献1参照)
また、捲回後の電極群の上下部端面を熱溶着する構成も提案されている。(例えば特許文献2参照)
【0006】
【特許文献1】
特開昭63−239766号公報
【特許文献2】
特開平1−122574号公報
【0007】
【発明が解決しようとする課題】
しかしながら、セパレータを溶着して極板を包むように構成する方法は、極板が平板で積層するいわゆる積層型の電池においては構わないが、現在、主として使われている捲回型の電池では、捲回時にセパレータがしわになり、製造が困難になるという課題があった。
【0008】
また、捲回後の電極群の上下部端面を熱溶着する構成は、端面にあるセパレータを連続して何重にも溶着するため、溶着による内部短絡を防ぐ効果と電解液の含浸性を両立させるのが困難であった。
【0009】
本発明は、上記の課題を解決し、捲回が容易で、かつ確実な短絡の防止と優れた電解液の含浸性をもつ捲回型電池を提供することを目的とする。
【0010】
【課題を解決するための手段】
上記課題を解決するために本発明は、捲回型電極群の構成工程において、正極または負極のどちらか一方の極板の表裏に存在するセパレータ同士の両端を熱溶着しつつ捲回するものとした。
【0011】
これにより、捲回型電極群であってもセパレータにしわがよらないで溶着することが出来る。
【0012】
また、熱溶着は、一定間隔でミシン目状に行なうことが好ましい。
【0013】
【発明の実施の形態】
本発明の請求項1に記載の発明は、正極と負極とをセパレータを介して捲回して電極群を構成する捲回型電池の製造法において、前記電極群の捲回工程は、正極または負極のどちらか一方の極板の表裏に存在するセパレータ同士の両端を熱溶着しつつ捲回することを特徴としたものであり、電池に異常な外的衝撃や荷重あるいは異常な温度が与えられても容易に正極と負極が接触しないという作用を有する。
【0014】
また、熱溶着しつつ捲回することにより、捲回型電極群であってもセパレータにしわがよらないで溶着することが出来、電池缶への挿入が容易になり、電池の高容量化も図れるという効果もある。溶着は、一枚の極板の表裏の2枚のみの間で行なうため、全部を溶着しても一部に溶着しない部分を設けても良い。
【0015】
本発明の請求項2に記載の発明は、請求項1に記載の捲回型電池の製造法において、熱溶着は一定間隔でミシン目状に行なうこととしたものであり、電解液の含浸性が良く、高温下でのセパレータ収縮力が均等に分散し、セパレータ自身の機械的影響も少なくて良い。このミシン目状の間隔は、使用するセパレータおよび電解液により、安全性と電解液の含浸性を勘案して適宜選択できる。
【0016】
【実施例】
以下、実施例について、リチウムイオン二次電池を例に挙げ、図1および図2を用いて詳細な説明する。
<実施例電池A>
(正極の作製)
所定量のLiCoO2からなる正極活物質、アセチレンブラック(AB)からなる導電材、PVdFからなる結着剤、N−メチル−2−ピロリドン(NMP)からなる溶媒を混練分散して正極合剤ペーストを作製し、厚さ15μmのアルミニウム(Al)箔からなる集電体に塗着した。その後、乾燥と圧延を行い、所定の寸法に切断してリチウムイオン二次電池用正極板を作製した。尚、正極の幅は54mmである。
【0017】
(負極の作製)
次に、グラファイトと結着材および増粘材と純水を用いて負極ペーストを作製し、厚さ12μmの銅(Cu)箔からなる集電体に塗着した。その後、乾燥と圧延を行い、所定の寸法に切断してリチウムイオン二次電池用負極板を作製した。尚、負極の幅は56mmである。
【0018】
(電極群の作製)
次に正極板と負極板と厚さ20μm、幅60mmの微多孔性ポリエチレン樹脂製のセパレータを用いて、図1のように電極群を構成した。正極1には、正極リード5が溶接され、負極2には負極リード6が溶接されている。まず、順に負極2、セパレータ3、正極1、セパレータ3を積層して捲回した。捲回の過程においては、正極1の表裏に存在しているセパレータ3同士の端部を10mm間隔で3mm熱溶着させ、正極1を包み込むようにさせた。4がセパレータ熱溶着部である。得られた電極群を実施例電極群Aとした。
【0019】
得られた実施例電極群Aを円筒型の金属ケースに収納した後、正極リード5は封口板と、負極リード6は金属ケースと電気的に接続となるように溶接した。その後電解液を注液し、封口板で封口した。封口後、所定時間放置させ、さらに所定の電気量を充電してリチウムイオン二次電池を作製した。この電池は直径18mm、総高65mmで電池容量が1800mAhであり、実施例電池Aとした。<実施例電池B>
図2に示すように、実施例電池Aと同じ正極1と負極2とセパレータ3を用い、順にセパレータ3、負極2、セパレータ3、正極1を積層して捲回した。捲回の過程においては、負極2の表裏に存在しているセパレータ3同士の端部を10mm間隔で2mm熱溶着させ、負極2を包み込むようにした。得られた電極群を実施例電極群Bとした。
【0020】
以降、実施例電池Aと同様にして実施例電池Bを作製した。
<比較例電池A>
正極板と負極板とを厚さ20μm、幅60mmの微多孔性ポリエチレン樹脂製のセパレータを介して捲回した電極群を比較例電極群Aとした。比較例電極群Aは実施例電極群AまたはBのように電極群端部のセパレータには熱溶着が施されていない。これを金属ケースに挿入した後、実施例電池と同様に電池を完成させ、比較例電池Aとした。
<電池の安全性評価>
(耐熱試験)
電池を1.8Aの電流で4.2Vまで充電し、以降、電池の電圧が4.2Vを維持するように充電電流値を減衰させ、充電電流値が0.1Aになるまで充電した。
【0021】
充電状態の実施例電池A、Bおよび比較例電池Aをそれぞれ昇温炉に投入し、20℃から150℃まで5℃/分の速度で昇温炉を昇温した。昇温炉が150℃に到達した後は、炉内温度が150℃を維持させた。
【0022】
尚、電池には試験中の挙動を観測するため電池温度測定用に、表面に熱電対を取りつけた。
【0023】
耐熱試験の安全性については、150℃に到達してから3時間とした。
<評価結果>
比較例電池1は電池温度が150℃に到達してから約30分後に急激に温度が上昇した。
【0024】
一方、本発明である実施例電池AおよびBは150℃に到達した後に温度上昇が観測されず、試験中異常がなかった。比較例電池は昇温過程でセパレータが幅方向に収縮したため正極と負極が局所で短絡し、短絡ジュール熱によって電池の熱暴走温度に達したと推定できた。他方、実施例電池は電極を挟むようにしてセパレータ同士が熱溶着されているので、セパレータ収縮による局所的な短絡はなかったと推定できた。
【0025】
本発明の実施では円筒電池でその効果を示したが、楕円状あるいは扁平状で捲回した電極群であっても同じ効果が得られる。
【0026】
【発明の効果】
本発明は電池に外的衝撃や荷重あるいは異常な温度が与えられても容易に正極と負極が接触しないような構造にすることによって、安全性の高い捲回型電池が提供できる。
【図面の簡単な説明】
【図1】本発明の実施例電極群Aの概略図
【図2】本発明の実施例電極群Bの概略図
【符号の説明】
1 正極
2 負極
3 セパレータ
4 セパレータ熱溶着部
5 正極リード
6 負極リード[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a battery, and more particularly to a winding process of the electrode group.
[0002]
[Prior art]
In recent years, electronic devices have become rapidly portable and cordless. Among them, power supplies for laptop computers, mobile phones, and AV equipment, which are particularly popular, include conventional aqueous secondary batteries (nickel cadmium storage batteries, nickel metal hydride storage batteries) and smaller, lighter, higher energy density lithium ions. Small secondary batteries such as secondary batteries are mainly used.
[0003]
As the portability and diversification of devices increase, further improvements in reliability are necessary for small secondary batteries. There are some problems, but among them, there is a problem that the separator cannot keep the positive electrode and the negative electrode separated from each other due to abnormal impact on the battery or abnormal heating, and Joule heat is generated at the short-circuit location.
[0004]
The separator is required to have a function of maintaining the separation between the positive electrode and the negative electrode with sufficient mechanical and thermal strength. For example, a separator used in a lithium ion secondary battery is generally a microporous film made of polyethylene or polypropylene, and has a problem that it is easily and significantly contracted by heating unless the film is tensioned. .
[0005]
Conventionally, in order to prevent an internal short circuit in a battery, a method of welding a separator and wrapping an electrode plate has been proposed. (For example, see Patent Document 1)
In addition, a configuration in which the upper and lower end faces of the electrode group after winding are thermally welded has been proposed. (For example, see Patent Document 2)
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 63-239766 [Patent Document 2]
Japanese Patent Laid-Open No. 1-122574 [0007]
[Problems to be solved by the invention]
However, the method of welding the separator and wrapping the electrode plate may be a so-called laminated battery in which the electrode plate is laminated on a flat plate, but in the wound type battery mainly used at present, There was a problem that the separator was wrinkled during rotation, making it difficult to manufacture.
[0008]
In addition, the structure where the upper and lower end faces of the electrode group after winding are heat-welded continuously welds the separators on the end faces in layers, so both the effect of preventing internal short circuit due to welding and the impregnation of the electrolyte are compatible. It was difficult to do.
[0009]
An object of the present invention is to solve the above-described problems, and to provide a wound battery that is easy to wind and has a reliable prevention of short circuit and excellent electrolyte impregnation.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a winding type electrode group in which the two ends of the separators existing on the front and back of either the positive electrode or the negative electrode are wound while being thermally welded. did.
[0011]
Thereby, even if it is a wound type electrode group, a separator can be welded without wrinkles.
[0012]
Moreover, it is preferable to perform heat welding in a perforated pattern at regular intervals.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to
[0014]
In addition, by winding while heat-welding, even a wound electrode group can be welded without wrinkling the separator, and can be easily inserted into a battery can, and the capacity of the battery can be increased. There is also an effect. Since welding is performed between only two electrodes on the front and back of one electrode plate, a portion that is not welded even if all of them are welded may be provided.
[0015]
According to a second aspect of the present invention, in the method for manufacturing a wound battery according to the first aspect, the thermal welding is performed in a perforated manner at regular intervals. The separator shrinkage force at high temperature is evenly distributed, and the mechanical influence of the separator itself may be small. This perforated interval can be appropriately selected depending on the separator and the electrolytic solution used in consideration of safety and the impregnation property of the electrolytic solution.
[0016]
【Example】
Hereinafter, examples will be described in detail with reference to FIGS. 1 and 2 by taking a lithium ion secondary battery as an example.
<Example battery A>
(Preparation of positive electrode)
A positive electrode mixture paste prepared by kneading and dispersing a predetermined amount of a positive electrode active material made of LiCoO 2 , a conductive material made of acetylene black (AB), a binder made of PVdF, and a solvent made of N-methyl-2-pyrrolidone (NMP). Was applied to a current collector made of aluminum (Al) foil having a thickness of 15 μm. Then, drying and rolling were performed, and it cut | disconnected to the predetermined dimension, and produced the positive electrode plate for lithium ion secondary batteries. The width of the positive electrode is 54 mm.
[0017]
(Preparation of negative electrode)
Next, a negative electrode paste was prepared using graphite, a binder, a thickener, and pure water, and applied to a current collector made of a copper (Cu) foil having a thickness of 12 μm. Then, drying and rolling were performed, and it cut | disconnected to the predetermined dimension, and produced the negative electrode plate for lithium ion secondary batteries. The width of the negative electrode is 56 mm.
[0018]
(Production of electrode group)
Next, an electrode group was configured as shown in FIG. 1 using a positive electrode plate, a negative electrode plate, and a separator made of a microporous polyethylene resin having a thickness of 20 μm and a width of 60 mm. A
[0019]
After the obtained example electrode group A was housed in a cylindrical metal case, the
As shown in FIG. 2, the same
[0020]
Thereafter, Example Battery B was produced in the same manner as Example Battery A.
<Comparative battery A>
An electrode group in which the positive electrode plate and the negative electrode plate were wound through a separator made of a microporous polyethylene resin having a thickness of 20 μm and a width of 60 mm was used as Comparative Example Electrode Group A. In Comparative Example Electrode Group A, as in Example Electrode Group A or B, the electrode group end separator is not thermally welded. After this was inserted into a metal case, the battery was completed in the same manner as in the example battery, and a comparative example battery A was obtained.
<Battery safety evaluation>
(Heat resistance test)
The battery was charged to 4.2 V with a current of 1.8 A, and thereafter, the charging current value was attenuated so that the battery voltage was maintained at 4.2 V, and the battery was charged until the charging current value became 0.1 A.
[0021]
The charged example batteries A and B and comparative battery A were charged into a heating furnace, and the heating furnace was heated from 20 ° C. to 150 ° C. at a rate of 5 ° C./min. After the heating furnace reached 150 ° C., the furnace temperature was maintained at 150 ° C.
[0022]
In addition, in order to observe the behavior under test in the battery, a thermocouple was attached to the surface for battery temperature measurement.
[0023]
About the safety | security of a heat test, it was set as 3 hours after reaching | attaining 150 degreeC.
<Evaluation results>
In
[0024]
On the other hand, in Example batteries A and B according to the present invention, no temperature increase was observed after reaching 150 ° C., and there was no abnormality during the test. In the comparative battery, the separator contracted in the width direction during the temperature rising process, so the positive electrode and the negative electrode were locally short-circuited, and it was estimated that the thermal runaway temperature of the battery was reached by the short-circuit Joule heat. On the other hand, in the example battery, the separators were thermally welded so as to sandwich the electrode, so it was estimated that there was no local short circuit due to the separator contraction.
[0025]
In the practice of the present invention, the effect was shown with a cylindrical battery, but the same effect can be obtained even with an electrode group wound in an elliptical shape or a flat shape.
[0026]
【The invention's effect】
According to the present invention, a highly safe wound battery can be provided by adopting a structure in which the positive electrode and the negative electrode are not easily contacted even when an external impact, load, or abnormal temperature is applied to the battery.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an example electrode group A of the present invention. FIG. 2 is a schematic diagram of an example electrode group B of the present invention.
DESCRIPTION OF
Claims (3)
前記電極群の捲回工程は、まず、順に負極、セパレータ、正極、セパレータを積層して捲回し、前記捲回の過程において、正極の表裏に存在しているセパレータ同士の端部を熱溶着させ、前記正極を包み込むようにすることを特徴とする捲回型電池の製造法。In a method for manufacturing a wound battery in which a positive electrode and a negative electrode are wound through a separator to constitute an electrode group,
In the winding process of the electrode group, first, a negative electrode, a separator, a positive electrode, and a separator are sequentially stacked and wound, and in the winding process, end portions of the separators existing on the front and back of the positive electrode are thermally welded. A method for manufacturing a wound battery , wherein the positive electrode is wrapped .
前記電極群の捲回工程は、まず、順にセパレータ、負極、セパレータ、正極を積層して捲回し、前記捲回の過程において、負極の表裏に存在しているセパレータ同士の端部を熱溶着させ、前記負極を包み込むようにすることを特徴とする捲回型電池の製造法。In a method for manufacturing a wound battery in which a positive electrode and a negative electrode are wound through a separator to constitute an electrode group,
In the winding process of the electrode group, first, a separator, a negative electrode, a separator, and a positive electrode are sequentially laminated and wound, and in the winding process, the end portions of the separators existing on the front and back of the negative electrode are thermally welded. A method of manufacturing a wound battery , wherein the negative electrode is wrapped .
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JP2002364874A JP4403698B2 (en) | 2002-12-17 | 2002-12-17 | Winding battery manufacturing method |
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JP2002364874A JP4403698B2 (en) | 2002-12-17 | 2002-12-17 | Winding battery manufacturing method |
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JP2004199924A JP2004199924A (en) | 2004-07-15 |
JP4403698B2 true JP4403698B2 (en) | 2010-01-27 |
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