JPH09245761A - Battery separator and manufacture thereof - Google Patents
Battery separator and manufacture thereofInfo
- Publication number
- JPH09245761A JPH09245761A JP8048572A JP4857296A JPH09245761A JP H09245761 A JPH09245761 A JP H09245761A JP 8048572 A JP8048572 A JP 8048572A JP 4857296 A JP4857296 A JP 4857296A JP H09245761 A JPH09245761 A JP H09245761A
- Authority
- JP
- Japan
- Prior art keywords
- porous
- polyethylene
- film
- molecular weight
- weight
- 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
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Cell Separators (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、電池用、特にＬｉ
イオン二次電池等の非水電解質２次電池用に使用する電
池用セパレータおよびその製造方法に関するものであ
る。FIELD OF THE INVENTION The present invention relates to batteries, especially Li.
The present invention relates to a battery separator used for a non-aqueous electrolyte secondary battery such as an ion secondary battery and a manufacturing method thereof.
【０００２】[0002]
【従来の技術】近年、小型電池は電子機器、特に携帯用
機器の電源として、高容量を実現し得るＬｉイオン電池
の開発がなされている。Ｌｉイオン電池は、リチウムお
よびリチウムイオンを活物質とし、リチウム金属または
リチウム合金を負極に用い、電解液はエーテルやエステ
ルなど非水溶媒を使用する。2. Description of the Related Art In recent years, a small-sized battery has been developed as a power source for electronic devices, particularly portable devices, as a Li-ion battery capable of realizing a high capacity. Li-ion batteries use lithium and lithium ions as active materials, use lithium metal or lithium alloy for the negative electrode, and use a nonaqueous solvent such as ether or ester as the electrolytic solution.
【０００３】このＬｉイオン二次電池に用いられるセパ
レータは、非水電解液に安定で、かつ電解液が十分に含
有できしかも抵抗が低いことが要求されることから、多
孔性の膜が使用され、膜の材質として、電池の組立て時
における取扱易さ、電池の異常時における電流の遮断機
能（シャットダウン機能）を有するという安全性、電解
液の漏れを起こさないなどを考慮して、従来、ポリエチ
レン、ポリプロピレン、親水性ポリテトラフルオロエチ
レンなどが用いられていた。A porous membrane is used for the separator used in this Li-ion secondary battery because it is required to be stable in a non-aqueous electrolytic solution, sufficiently contain the electrolytic solution, and have low resistance. In consideration of the ease of handling when assembling a battery, the safety of having a current cutoff function (shutdown function) when the battery is abnormal, and the fact that electrolyte does not leak as the material of the membrane, polyethylene has been conventionally used. , Polypropylene, hydrophilic polytetrafluoroethylene, etc. were used.
【０００４】リチウム電池用セパレータとして、以下の
ようなポリエチレン微多孔膜を用いることが提案されて
いる（特開平３−１０５８５１号公報）。すなわち、重
量平均分子量が７×１０5以上の超高分子量ポリエチレ
ンを１重量％以上含有し、重量平均分子量／数平均分子
量が１０〜３００のポリエチレン組成物を用いるもので
ある。It has been proposed to use the following polyethylene microporous membrane as a lithium battery separator (Japanese Patent Laid-Open No. 3-105851). That is, a polyethylene composition containing 1% by weight or more of ultrahigh molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more and having a weight average molecular weight / number average molecular weight of 10 to 300 is used.
【０００５】また、異常時における温度上昇を抑制する
機能を付与するためにポリテトラフルオロエチレン（以
下、ＰＴＦＥと略す）多孔質膜の２０−８０％の低分子
量のポリエチレンを融着させたセパレータ（特開平１−
１８６７５１号公報）や、ＰＴＦＥ多孔質膜にポリエチ
レンまたはポリプロピレン膜を重ね合わせて用いること
が提案されてる（特開平５−２０５７２１号公報）。Further, in order to impart a function of suppressing a temperature rise in an abnormal condition, a separator formed by fusing 20-80% low molecular weight polyethylene of a polytetrafluoroethylene (hereinafter abbreviated as PTFE) porous film ( JP-A-1-
No. 186751), or the use of a polyethylene porous film laminated on a PTFE porous film (JP-A-5-205721).
【０００６】[0006]
【発明が解決しようとする課題】しかし、ポリエチレン
を単独でセパレータとして用いた場合、電池の使用時に
異常電流が流れ内部温度の過昇現象が生じた時にシャッ
トダウンが機能するものの、その後のジュール熱に伴う
温度上昇（１８０℃以上になることがある）に耐えきれ
ず、セパレータに大きな穴が開くことが懸念される。ポ
リプロピレンを用いた場合はポリエチレンよりも耐熱性
はあるものの、耐熱性はまだ十分なものとは言えず、ポ
リエチレンの場合と同様大きな穴が開きしかもシャット
ダウンが機能する温度が高過ぎて異常時に俊敏に機能し
ないという問題があった。However, when polyethylene is used alone as a separator, abnormal current flows during use of the battery and shutdown occurs when the internal temperature rises excessively. There is a concern that the separator will not be able to withstand the accompanying temperature rise (may reach 180 ° C. or higher) and that a large hole will be formed in the separator. Although heat resistance is higher than that of polyethylene when using polypropylene, it cannot be said that the heat resistance is still sufficient.As in the case of polyethylene, a large hole is opened and the temperature at which the shutdown function is too high There was a problem that it did not work.
【０００７】また、ＰＴＦＥ多孔膜にポリエチレン膜を
設けたセパレータは、異常時におけるシャットダウン機
能は果たすものの、下記の点で十分満足できるものはな
かった。すなわち、例えば、耐破膜性が低いためセパレ
ータを挿入するときに破れを生じる等、電池組立て時の
取扱性に問題があった。この理由は、ＰＴＦＥ多孔膜と
ポリエチレン膜を単なる重ねあわせのみで用いており接
着強度が十分ではないため、特に非延伸方向の引き裂き
強度の弱いＰＴＦＥ多孔膜を補強する役目をポリエチレ
ン膜が果たさないためと考えられる。また、接着強度を
高めるために、ポリエチレン多孔膜を軟化温度以上に加
熱すると、急激に多孔膜のポリエチレンが融解し、ＰＴ
ＦＥ多孔膜およびポリエチレン多孔膜の孔を閉塞してし
まい、逆に、積層の接着強度が弱いと電池組立時にセパ
レータが層間でずれが生じるため、保液量を一定に安定
して注入できないことになり、結果としていずれの場合
においても、十分な保液性を確保できず電池のサイクル
寿命を向上させることができない。以上に説明したよう
に、従来、異常時に俊敏にシャットダウンし、その後の
ジュール熱によって温度上昇してもセパレータに大きな
穴が開くことがなく、しかもいわゆる電池組立て時の取
扱性、電解液の濡れ性を満足する安定した高信頼性のセ
パレータは存在していなかった。Further, although the separator having the polyethylene membrane provided on the PTFE porous membrane fulfills the shutdown function in the event of an abnormality, none of the following is sufficiently satisfactory. That is, for example, there is a problem in handleability during battery assembly, such as breakage when a separator is inserted due to low film rupture resistance. The reason for this is that the PTFE porous film and the polyethylene film are used only by simply stacking them, and the adhesive strength is not sufficient, so that the polyethylene film does not function to reinforce the PTFE porous film, which has a particularly weak tear strength in the non-stretching direction. it is conceivable that. When the polyethylene porous film is heated above the softening temperature to increase the adhesive strength, the polyethylene of the porous film is rapidly melted and PT
The pores of the FE porous film and the polyethylene porous film are blocked, and conversely, if the adhesive strength of the stack is weak, the separator will shift between layers during battery assembly, so that the liquid retention amount cannot be constantly and stably injected. As a result, in any case, sufficient liquid retention cannot be secured and the cycle life of the battery cannot be improved. As described above, conventionally, agile shutdown in the event of an abnormality, large holes do not open in the separator even if the temperature rises due to subsequent Joule heat, and so-called handleability during battery assembly, wettability of electrolyte solution There was no stable and highly reliable separator satisfying the above condition.
【０００８】[0008]
【課題を解決するための手段】本発明者は、従来のセパ
レータの問題点を解決するために種々検討した結果、気
孔率が３０〜６０％の多孔性ＰＴＦＥ膜上に重量平均分
子量Ｍｗが１６万以上、重量平均分子量Ｍｗと数平均分
子量Ｍｎとの比（Ｍｗ／Ｍｎ）が４〜８であり、該多孔
性ポリエチレン膜中に含まれる低分子量のポリエチレン
の一部が前記多孔性ポリテトラフルオロエチレン膜の孔
内に融解浸入し固化してなるポリエチレン膜を設けるこ
とによって、電池組立て工程において破膜のような問題
が起きることなく取り扱うことができ、電解液に対する
漏れ性も高く、異常電流を遮断するシャットダウン機能
を備え、併せて、Ｌｉイオン電池に使用した場合にサイ
クル寿命特性が極めて良好である電池用セパレータを提
供できることを見出した。As a result of various studies to solve the problems of conventional separators, the present inventor found that a weight average molecular weight Mw of 16 was obtained on a porous PTFE membrane having a porosity of 30 to 60%. 10,000 or more, the ratio (Mw / Mn) of the weight average molecular weight Mw to the number average molecular weight Mn is 4 to 8, and a part of the low molecular weight polyethylene contained in the porous polyethylene membrane is the porous polytetrafluoro. By providing a polyethylene film formed by melting and infiltrating into the pores of the ethylene film and solidifying, it can be handled without causing problems such as membrane rupture in the battery assembly process, has high leakage to the electrolyte, and abnormal current Seeing that it is possible to provide a battery separator that has a shutdown function that shuts off and also has extremely good cycle life characteristics when used in a Li-ion battery. It was.
【０００９】本発明の電池用セパレータは、多孔性ＰＴ
ＦＥ膜上に前記多孔性ポリエチレン膜を設けるに際し、
該多孔性ポリエチレン膜中に含まれる低分子量のポリエ
チレンの融点以上高分子量のポリエチレンの融点以下で
加熱加圧することによって製造することができる。The battery separator of the present invention comprises a porous PT.
When the porous polyethylene film is provided on the FE film,
It can be produced by heating and pressing at a temperature above the melting point of the low molecular weight polyethylene contained in the porous polyethylene membrane and below the melting point of the high molecular weight polyethylene.
【００１０】本発明において用いられる多孔性ＰＴＦＥ
膜は気孔率が３０〜６０％のものである。気孔率は、電
池の充放電特性、電池組立て時のセパレータの取扱易さ
に大きく影響を及ぼすもので、気孔率が６０％を超える
と電池の内部抵抗が低減できて充放電特性の面では良い
が、その分実質ＰＴＦＥ分子の量が減ることになるため
セパレータとしてのいわゆる腰強度が低下して、電池組
立て時における短絡が多く発生するという実用上の問題
がある。逆に３０％未満だと電解液の保液性が低下し充
放電特性が著しく低下する。Porous PTFE used in the present invention
The membrane has a porosity of 30 to 60%. Porosity greatly affects the charge / discharge characteristics of the battery and the ease of handling the separator during battery assembly. If the porosity exceeds 60%, the internal resistance of the battery can be reduced, which is good in terms of charge / discharge characteristics. However, since the amount of substantial PTFE molecules is reduced accordingly, the so-called waist strength of the separator is lowered, and there is a practical problem that many short circuits occur during battery assembly. On the other hand, if it is less than 30%, the liquid retaining property of the electrolytic solution is deteriorated and the charge / discharge characteristics are significantly deteriorated.
【００１１】また、本発明において、多孔性ＰＴＦＥ膜
上に設ける多孔性ポリエチレン膜のポリエチレンの重量
平均分子量Ｍｗが１６万以上、重量平均分子量Ｍｗと数
平均分子量Ｍｎとの比（Ｍｗ／Ｍｎ）が４〜８である。
分子量分布が４未満だと多孔性ＰＴＦＥ膜上に多孔性ポ
リエチレン膜を設けるに際し、多孔性ポリエチレン膜中
の低分子量ポリエチレンの一部が融解し多孔性ＰＴＦＥ
膜の多孔内に入って固化してもその部分の強度が弱いた
め、十分な密着性が得られないからであり、８を超える
と密着性は良いもののシャットダウンの高速性の点で不
十分となるからである。Further, in the present invention, the weight average molecular weight Mw of polyethylene of the porous polyethylene membrane provided on the porous PTFE membrane is 160,000 or more, and the ratio (Mw / Mn) of the weight average molecular weight Mw to the number average molecular weight Mn is 4 to 8.
When the molecular weight distribution is less than 4, when the porous polyethylene film is provided on the porous PTFE film, a part of the low molecular weight polyethylene in the porous polyethylene film is melted and the porous PTFE film is melted.
This is because even if it enters the inside of the pores of the membrane and solidifies, the strength of that part is weak, so sufficient adhesion cannot be obtained. If it exceeds 8, the adhesion is good but the shutdown speed is insufficient. Because it will be.
【００１２】本発明の電池用セパレータを製造するに当
たり、多孔性ＰＴＦＥ膜上に多孔性ポリエチレン膜を設
けるに際し、該多孔性ポリエチレン膜中に含まれるポリ
エチレンの分子量のポリエチレンの融点以上高分子量の
ポリエチレンの融点以下で加熱加圧するのは、多孔性ポ
リエチレン膜中の低分子量ポリエチレンの一部が融解し
多孔性ＰＴＦＥ膜の多孔内に浸入させ固化させることに
よって多孔性ＰＴＦＥ膜と多孔性ポリエチレン膜との密
着性を向上させ、高分子量のポリエチレンによるシャッ
トダウン機能を維持させるためである。In the production of the battery separator of the present invention, when a porous polyethylene film is provided on a porous PTFE film, polyethylene having a molecular weight higher than the melting point of polyethylene contained in the porous polyethylene film is used. Heating and pressurizing below the melting point means that a part of the low-molecular-weight polyethylene in the porous polyethylene film is melted and penetrates into the pores of the porous PTFE film and solidifies to adhere to the porous PTFE film and the porous polyethylene film. This is to improve the property and maintain the shutdown function of high molecular weight polyethylene.
【００１３】[0013]
【発明の実施の形態】本発明の電池用セパレータは、透
気抵抗が通常８００以下とすることができる。ここに、
透気抵抗は、単位面積（６４５ｍｍ2）当たりの空気１
００ｍｌの移動時間（秒）を測定して求められる値で
（ＪＩＳ Ｐ８１１７−1980）、電解液中のＬｉイオン
の移動度を間接的に模擬できる。すなわち、透気抵抗が
小さければ電解液中の移動度が高くなり、電池の導電率
が向上し、内部抵抗が減少して電池の高容量化が実現で
きる。BEST MODE FOR CARRYING OUT THE INVENTION The battery separator of the present invention can have an air resistance of usually 800 or less. here,
Air resistance is 1 air per unit area (645mm 2 ).
The mobility of Li ions in the electrolytic solution can be indirectly simulated with a value obtained by measuring the migration time (second) of 00 ml (JIS P8117-1980). That is, if the air resistance is small, the mobility in the electrolytic solution is high, the conductivity of the battery is improved, the internal resistance is decreased, and the battery capacity can be increased.
【００１４】電池用セパレータの厚さは、電池の大きさ
にもよるが、電池の高容量化を考慮して３０μｍ以下に
設計される。３０μｍを超えると、巻き電池の巻数が減
って、電極の活物質の量が低下するため電池容量が不十
分なものとなるからである。しかしながら、厚さが１５
μｍ以下になると膜のいわゆる腰強度が弱すぎて電池の
組立て性や安全面で好ましくない。Although the thickness of the battery separator depends on the size of the battery, it is designed to be 30 μm or less in consideration of increasing the capacity of the battery. When it exceeds 30 μm, the number of windings of the wound battery is reduced and the amount of the active material of the electrode is reduced, so that the battery capacity becomes insufficient. However, the thickness is 15
If it is less than μm, the so-called waist strength of the membrane is too weak, which is not preferable in terms of battery assembly and safety.
【００１５】本発明に用いられる多孔性ポリエチレン膜
に含まれる低分子量のポリエチレンの融点は５０〜１１
０℃、高分子量のポリエチレンの融点は９０〜１８０℃
の範囲内で任意に選び、混合することによって、重量平
均分子量と数平均分子量との比を４〜８の範囲になるよ
うに、調整することができる。低分子量のポリエチレン
と高分子量のポリエチレンの融点差は、１０℃以上あっ
た方が、セパレータの製造時における加熱温度の設定が
容易になり好ましい。ポリエチレンの組合せとして、例
えば、融点７５℃の低分子量のポリエチレンと融点９０
℃の高分子量のポリエチレンとの組合せ、融点９５℃の
低分子量のポリエチレンと融点１１０℃の高分子量のポ
リエチレンとの組合せなどが考えられる。なお、本発明
において「低分子量」および「高分子量」というとき
は、絶対的な分子量の意味を指称するのではなく、互い
に相対する分子量の大きさを意味する。The low molecular weight polyethylene contained in the porous polyethylene membrane used in the present invention has a melting point of 50 to 11
0 ℃, melting point of high molecular weight polyethylene is 90-180 ℃
It is possible to adjust the ratio of the weight average molecular weight to the number average molecular weight to be in the range of 4 to 8 by arbitrarily selecting and mixing within the range. The difference in melting point between low-molecular-weight polyethylene and high-molecular-weight polyethylene is preferably 10 ° C. or more because the heating temperature during the production of the separator can be easily set. As a combination of polyethylene, for example, a low molecular weight polyethylene having a melting point of 75 ° C. and a melting point of 90
A combination with a high-molecular-weight polyethylene having a melting point of 95 ° C., a low-molecular-weight polyethylene having a melting point of 95 ° C., and a high-molecular-weight polyethylene having a melting point of 110 ° C. may be considered. In the present invention, the terms "low molecular weight" and "high molecular weight" do not mean absolute molecular weights, but rather magnitudes of molecular weights that are opposite to each other.
【００１６】本発明において、多孔性ポリエチレン膜の
厚さは、５〜１５μｍに設計するのが望ましい。５μｍ
以下だとシャットダウン機能が十分に発揮できないこと
があるからである。１５μｍ以上だとシャットダウン時
の熱収縮率が大き過ぎて多孔性ＰＴＦＥ膜が溶融したポ
リエチレンによって強く引っ張られて形状保持性が悪化
し、ポリエチレン層の遊離を促すなど、安全性の点で好
ましくない。In the present invention, the thickness of the porous polyethylene film is preferably designed to be 5 to 15 μm. 5 μm
This is because if it is below, the shutdown function may not be fully exerted. If it is 15 μm or more, the heat shrinkage ratio at shutdown is too large, the porous PTFE membrane is strongly pulled by the melted polyethylene, the shape retention is deteriorated, and the release of the polyethylene layer is promoted, which is not preferable in terms of safety.
【００１７】また、多孔性ＰＴＦＥ膜は、電解液の浸透
性、保持性の点から親水化処理されていることが望まし
い。親水化処理の方法として、例えば、ポリビニルアル
コールなどの水溶性ポリマーを含浸させ、電子線照射な
どを行う方法を採用することができる。本発明の電池用
セパレータを電池に組み込む場合は、負極のＬｉ電位に
おける多孔性膜の還元劣化を考慮すると、多孔性ポリエ
チレン膜側を負極に配置した方が望ましい。Further, the porous PTFE membrane is preferably hydrophilized from the viewpoint of permeability and retention of the electrolytic solution. As a method of hydrophilic treatment, for example, a method of impregnating a water-soluble polymer such as polyvinyl alcohol and performing electron beam irradiation can be adopted. When the battery separator of the present invention is incorporated in a battery, it is preferable to arrange the porous polyethylene film side on the negative electrode in consideration of reduction deterioration of the porous film at the Li potential of the negative electrode.
【００１８】[0018]
【実施例】実施例１ ポリビニルアルコールによる親水処理を施した気孔率６
０％、厚さ１５μｍの多孔性ＰＴＦＥ膜に、重量平均分
子量Ｍｗが１６万で、数平均分子量Ｍｎとの比Ｍｗ／Ｍ
ｎが４．５で厚さ５μｍである多孔性ポリエチレン膜を
１０５℃の温度で加熱ラミネータにより張り合わせてセ
パレータを作製した。このセパレータの透気抵抗は１０
０秒であった。EXAMPLES Example 1 Porosity 6 subjected to hydrophilic treatment with polyvinyl alcohol
The weight average molecular weight Mw is 160,000 and the ratio Mw / M to the number average molecular weight Mn is 0% in a porous PTFE membrane having a thickness of 15 μm.
A porous polyethylene membrane having an n of 4.5 and a thickness of 5 μm was laminated at a temperature of 105 ° C. with a heating laminator to prepare a separator. The air resistance of this separator is 10
It was 0 seconds.
【００１９】実施例２ ６／４モル％のエバール（エチレンビニルアルコール共
重合体）溶液による親水処理を施した気孔率４０％、厚
さ１５μｍの多孔性ＰＴＦＥ膜に、重量平均分子量Ｍｗ
が２０．５万で、Ｍｗ／Ｍｎが５で、厚さ１０μｍであ
る多孔性ポリエチレン膜を１１０℃の温度で加熱ラミネ
ータにより張り合わせてセパレータを作製した。このセ
パレータの透気抵抗は６００秒であった。 Example 2 A porous PTFE membrane having a porosity of 40% and a thickness of 15 μm, which had been subjected to a hydrophilic treatment with a 6/4 mol% Eval (ethylene vinyl alcohol copolymer) solution, was added to a weight average molecular weight Mw.
Was 205,000, Mw / Mn was 5 and the thickness was 10 μm, and a porous polyethylene membrane was laminated at a temperature of 110 ° C. with a heating laminator to prepare a separator. The air resistance of this separator was 600 seconds.
【００２０】実施例３ 親水化処理していない多孔性ＰＴＦＥ膜を用いた以外
は、実施例１と同様の条件でセパレータを作製した。 Example 3 A separator was produced under the same conditions as in Example 1 except that a porous PTFE membrane that had not been hydrophilized was used.
【００２１】実施例４ 融点７５℃の低分子量（Ｍｗ１３万）のポリエチレン粉
体と融点１２０℃の高分子量（Ｍｗ２５万）のポリエチ
レン粉体とを８／２の重量比率で混練機により１３０℃
で混ぜ合わせて、厚さ５０μｍの膜を成型した。得られ
たポリエチレン膜の重量平均分子量１６万、Ｍｗ／Ｍｎ
が４．２であった。その後、一軸延伸法により８５０％
延伸して、１０μｍ、気孔率５５％、透気抵抗５００秒
の多孔性ポリエチレン膜を作製した。次いで、８０℃に
て気孔率６０％、厚さ１５μｍの多孔性ＰＴＦＥ膜と貼
り合わせて、セパレータを作製した。このセパレータの
透気抵抗は３００秒であった。 Example 4 A low molecular weight (Mw 130,000) polyethylene powder having a melting point of 75 ° C. and a high molecular weight (Mw 250,000) polyethylene powder having a melting point of 120 ° C. were mixed at a weight ratio of 8/2 at 130 ° C. by a kneader.
And mixed to form a film having a thickness of 50 μm. The obtained polyethylene film had a weight average molecular weight of 160,000 and Mw / Mn.
Was 4.2. Then 850% by uniaxial stretching method
By stretching, a porous polyethylene membrane having a pore size of 10 μm, a porosity of 55% and an air resistance of 500 seconds was prepared. Then, it was bonded to a porous PTFE membrane having a porosity of 60% and a thickness of 15 μm at 80 ° C. to prepare a separator. The air resistance of this separator was 300 seconds.
【００２２】比較例１ 気孔率８０％の多孔性ＰＴＦＥ膜を用いた以外は実施例
１と同様にしてセパレータを作製した。 Comparative Example 1 A separator was prepared in the same manner as in Example 1 except that a porous PTFE membrane having a porosity of 80% was used.
【００２３】比較例２ 気孔率４０％、厚さ２５μｍ、透気抵抗４００秒の多孔
性ＰＴＦＥ膜を用いた以外は、実施例１と同様にしてセ
パレータを作製した。 Comparative Example 2 A separator was produced in the same manner as in Example 1 except that a porous PTFE membrane having a porosity of 40%, a thickness of 25 μm and an air resistance of 400 seconds was used.
【００２４】比較例３ Ｍｗ／Ｍｎが２．５のポリエチレンを使用する以外は、
実施例１と同様にしてセパレータを作製した。 Comparative Example 3 Except that polyethylene having Mw / Mn of 2.5 was used,
A separator was produced in the same manner as in Example 1.
【００２５】比較例４ 気孔率４０％、厚さ２５μｍ、透気抵抗４００の多孔性
ポリプロピレン膜を用いた以外は、実施例１と同様にし
てセパレータを作製した。 Comparative Example 4 A separator was produced in the same manner as in Example 1 except that a porous polypropylene film having a porosity of 40%, a thickness of 25 μm and an air resistance of 400 was used.
【００２６】以上のようにして得られたセパレータにつ
いて下記の安全試験および破膜強度試験、これらセパレ
ータを用いて組み立てたコイン型電池のサイクル寿命評
価を行った。これらの試験結果を表１に示す。The separator obtained as described above was subjected to the following safety test and membrane rupture strength test, and cycle life evaluation of a coin type battery assembled using these separators. Table 1 shows the test results.
【００２７】＜安全試験１＞セパレータを１３０℃２分
間加熱し、室温に戻した後透気抵抗を測定した。 ＜安全試験１＞セパレータを１８０℃２分間加熱し、形
状保持性能を目視評価した。評価基準は、形状変化しな
なかったものを「良」、形状変したものを「不良」とし
た。 ＜破膜強度試験＞電池組立性能として、セパレータを電
池に組立てる際にセパレータが破膜するのを模擬的に評
価するため、セパレータに直径１．０ｍｍ、先端アール
０．５ｍｍのピンを３０ｃｍ／分の速度で突き当て、破
膜した時の荷重を読み取った。 ＜サイクル寿命＞電池容量の維持率が８０％以下になる
サイクル数をサイクル寿命とした。 ＜電解液の漏れ性＞セパレータを１ｃｍ角に切取り、こ
の切片をエチレンカーボネート／ジエチレンカーボネー
ト（１：１容積％）の電解液に浸漬させ、透明になるま
で時間を測定した。<Safety Test 1> The separator was heated at 130 ° C. for 2 minutes and returned to room temperature, and then the air resistance was measured. <Safety Test 1> The separator was heated at 180 ° C. for 2 minutes, and the shape retention performance was visually evaluated. The evaluation criteria were "good" when the shape was not changed and "bad" when the shape was changed. <Breakdown strength test> As a battery assembly performance, a pin having a diameter of 1.0 mm and a tip radius of 0.5 mm is attached to the separator at 30 cm / min in order to evaluate the separator as a film when it is assembled into a battery. The load when the film was ruptured was read. <Cycle life> The cycle life was defined as the number of cycles at which the battery capacity retention rate was 80% or less. <Leakage of Electrolyte Solution> The separator was cut into 1 cm square pieces, and this piece was immersed in an electrolyte solution of ethylene carbonate / diethylene carbonate (1: 1 volume%), and the time until it became transparent was measured.
【００２８】[0028]
【表１】 [Table 1]
【００２９】[0029]
【発明の効果】本発明の電池用セパレータは、表１から
分かる通り、Ｌｉイオン電池において電解液に対する濡
れ性、耐破膜性、シャットダウン性能、耐熱性に優れて
いるので、このセパレータを用いた電池は安全性、電池
組立性だけではなく、電池の寿命も優れたものである。As can be seen from Table 1, the battery separator of the present invention is excellent in the wettability with respect to the electrolytic solution, the membrane rupture resistance, the shutdown performance and the heat resistance in the Li-ion battery. Therefore, this separator was used. Batteries are not only safe and easy to assemble, but also have excellent battery life.
Claims (2)
ラフルオロエチレン膜と該膜上に設けられた多孔性ポリ
エチレン膜からなる電池用セパレータであって、前記多
孔性ポリエチレン膜が重量平均分子量Ｍｗが１６万以
上、重量平均分子量Ｍｗと数平均分子量Ｍｎとの比（Ｍ
ｗ／Ｍｎ）が４〜８であり、該多孔性ポリエチレン膜中
に含まれる低分子量のポリエチレンの一部が前記多孔性
ポリテトラフルオロエチレン膜の孔内に融解浸入し固化
してなることを特徴とする電池用セパレータ。1. A battery separator comprising a porous polytetrafluoroethylene membrane having a porosity of 30 to 60% and a porous polyethylene membrane provided on the membrane, wherein the porous polyethylene membrane has a weight average molecular weight. Mw is 160,000 or more, the ratio of the weight average molecular weight Mw to the number average molecular weight Mn (M
w / Mn) is 4 to 8 and a part of the low molecular weight polyethylene contained in the porous polyethylene membrane is melted and infiltrated into the pores of the porous polytetrafluoroethylene membrane to be solidified. And a battery separator.
ラフルオロエチレン膜上に、重量平均分子量Ｍｗが１６
万以上、重量平均分子量Ｍｗと数平均分子量Ｍｎとの比
（Ｍｗ／Ｍｎ）が４〜８である多孔性ポリエチレン膜
を、該多孔性ポリエチレン膜中に含まれる低分子量のポ
リエチレンの融点以上高分子量のポリエチレンの融点以
下で加熱加圧することを特徴とする電池用セパレータの
製造方法。2. A weight average molecular weight Mw of 16 on a porous polytetrafluoroethylene membrane having a porosity of 30 to 60%.
10,000 or more, a porous polyethylene membrane having a ratio (Mw / Mn) of the weight average molecular weight Mw to the number average molecular weight Mn of 4 to 8 is used, which has a molecular weight higher than the melting point of the low molecular weight polyethylene contained in the porous polyethylene membrane. A method for manufacturing a battery separator, comprising heating and pressurizing at a temperature not higher than the melting point of polyethylene.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8048572A JPH09245761A (en) | 1996-03-06 | 1996-03-06 | Battery separator and manufacture thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8048572A JPH09245761A (en) | 1996-03-06 | 1996-03-06 | Battery separator and manufacture thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09245761A true JPH09245761A (en) | 1997-09-19 |
Family
ID=12807118
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8048572A Pending JPH09245761A (en) | 1996-03-06 | 1996-03-06 | Battery separator and manufacture thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09245761A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002050336A (en) * | 2000-08-07 | 2002-02-15 | Asahi Kasei Corp | Separator for zinc halogen battery |
| JP2002270223A (en) * | 2001-03-07 | 2002-09-20 | Matsushita Electric Ind Co Ltd | Non-aqueous electrolyte secondary battery |
| JP2009224343A (en) * | 2009-07-08 | 2009-10-01 | Sumitomo Chemical Co Ltd | Separator for nonaqueous electrolyte secondary battery |
| KR20190072295A (en) * | 2017-12-15 | 2019-06-25 | 주식회사 엘지화학 | Laminated separator composite with two-types of separators, manufacturing method thereof, and lithium secondary battery comprising the same |
-
1996
- 1996-03-06 JP JP8048572A patent/JPH09245761A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002050336A (en) * | 2000-08-07 | 2002-02-15 | Asahi Kasei Corp | Separator for zinc halogen battery |
| JP2002270223A (en) * | 2001-03-07 | 2002-09-20 | Matsushita Electric Ind Co Ltd | Non-aqueous electrolyte secondary battery |
| JP2009224343A (en) * | 2009-07-08 | 2009-10-01 | Sumitomo Chemical Co Ltd | Separator for nonaqueous electrolyte secondary battery |
| KR20190072295A (en) * | 2017-12-15 | 2019-06-25 | 주식회사 엘지화학 | Laminated separator composite with two-types of separators, manufacturing method thereof, and lithium secondary battery comprising the same |
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