JP4110632B2

JP4110632B2 - Sealed battery

Info

Publication number: JP4110632B2
Application number: JP27721498A
Authority: JP
Inventors: 聡三浦; 琢也中嶋; 賢治水野; 義高松政; 浩司芳澤
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1998-09-30
Filing date: 1998-09-30
Publication date: 2008-07-02
Anticipated expiration: 2018-09-30
Also published as: JP2000106156A

Description

【０００１】
【発明の属する技術分野】
本発明は、注液口を有する密閉電池に関するものである。
【０００２】
【従来の技術】
近年、携帯機器の駆動用電源として、各種の小型二次電池が用いられている。このような小型二次電池として、従来ではニッケルカドミウム電池，ニッケル水素電池が用いられ、近年では特にリチウムイオン二次電池等が用いられている。
【０００３】
このような密閉電池の封口方法として、封口板とケース開口部をレーザー溶接により密閉したものや、封口板をガスケットを介してケースとかしめ封口を行ったものがある。
【０００４】
特に、前者のような封口板とケース開口部をレーザー溶接して封口した電池では、その封口する方法として、まず注液を行い、その後、封口板とケース開口部とをレーザー溶接して封口する場合と、封口板とケース開口部をレーザー溶接した後に、封口板または電池ケースの注液口から注液を行い封口栓をする場合がある。特に、後者のような封口板とケース開口部をレーザー溶接した後に、封口板、または電池ケースの注液口から注液を行い封口栓をする電池においては、封口栓と封口板、または封口栓と電池ケースを溶接する時の溶接不良を低減させ密閉性の高い電池を提供するために、特開平９−２８８９９９号公報では図６の（ａ），（ｂ），（ｃ）に示したように、レーザー溶接ができるように全体が金属製で注液口に密挿される密挿段部Ａとレーザー溶接する鍔部Ｂとを一体にした封口栓形状が提案されている。
【０００５】
【発明が解決しようとする課題】
従来の封口板と電池ケースを溶接した後、封口板の注液口または電池ケースの注液口から注液を行い、その注液口に封口栓を溶接する場合、その溶接不良を増加させる原因として、溶接位置への位置決めが困難であるということと、封口栓を注液口に挿入した時に電解液の這い上がりにより、溶接部近傍への電解液の付着や、溶接部分への電解液の付着によって、封口栓の溶接時に穴あきが生じることがある。特に、図６の（ａ），（ｂ），（ｃ）にそれぞれ示したような従来の封口栓の形状では、電解液が封口栓に付着して溶接不良を起こす問題があった。このような溶接不良は電池の密閉性を低下させ、漏液や生産性を低下させる原因になっていた。
【０００６】
本発明は前述した課題を解決すべく、溶接時の不良を低減させ、信頼性の高い密閉電池を提供することを目的とする。
【０００７】
【課題を解決するための手段】
この課題を解決するために本発明は、注液口に密挿する封口栓の密挿段部は樹脂製とした封口栓を用いることにより、注液口と封口栓の密閉性を高め、封口栓を挿入した時の電解液の這い上がりをなくし、封口栓の溶接部分への電解液の付着を防ぐように構成すると共に、注液口に密挿される密挿段部の寸法を注液口壁面の寸法に合致する寸法として、封口栓挿入時の電解液の這い上がりを低下させ、さらに密挿段部と鍔部とが連接する内周部には凹形状の液だまりをつくり、封口栓溶接部分までの電解液の浸透を遅らせ、鍔部の下面には直線部を形成することにより、溶接時の熱の影響を低下させるように構成したものである。
【０００８】
これにより、封口栓の溶接時の電解液の付着による溶接不良を低減させ、信頼性の高い密閉電池が得られる。
【０００９】
【発明の実施の形態】
本発明の請求項１に記載の発明は、電解液の注液口に密挿される封口栓の密挿段部は樹脂製とし、または樹脂製の栓体を挿入後、金属製の封口栓を樹脂製の栓体に挿入し、注液口と封口栓の密閉性をさらに高め、電解液の上昇を防ぎ溶接不良を低減させるという作用を有する。
【００１０】
請求項２に記載の発明は、封口栓のレーザー溶接部に薄肉部を設けることにより、レーザー出力を弱くでき、注液口までの熱影響を少なくすることにより、電解液の上昇を減少させるという作用を有する。
【００１１】
請求項３に記載の発明は、封口栓の密挿段部と、注液口の壁面との間に封止剤を塗着し、注液口と封口栓の密閉性を高め、溶接不良を低減させるという作用を有する。
【００１２】
請求項４に記載の発明は、電解液の注液口において封口栓嵌め込み側の周縁部上端を面取りしたものであり、密挿段部を有する封口栓の挿入を容易にし、特に封口栓の挿入による溶接不良を低減させるという作用を有する。
【００１３】
請求項５に記載の発明は、極板群を収容した電池ケースの上部開口部に、封口板を載置して溶接すると共に、封口板の注液口、または電池ケースの注液口から電解液を注入した後、前記注液口に封口栓を嵌め込んで封口した電池において、前記封口栓の密挿段部の径方向の寸法を注液口壁面間の寸法に対し±０．１ｍｍとし、その先端は曲面とし、封口栓挿入時の電解液の這い上がりを防止し、かつ密挿段部と鍔が連接する内周縁に凹部状のたまり部を形成し封口栓の溶接部分までの電解液の浸透を遅らせ、また鍔部の下面は０．３ｍｍ以上の直線部とした封口栓により封口したもので、溶接時の熱の影響を低下させ、溶接不良を低減させるという作用を有する。
【００１４】
請求項６に記載の発明は、金属製封口栓のレーザー溶接部に薄肉部を設けることにより、レーザー出力を弱くでき、注液口までの熱影響を少なくすることにより電解液の上昇を減少させるという作用を有する。
【００１５】
請求項７に記載の発明は、金属製の密挿段部を有する封口栓と、注液口の壁面との間に封止剤を塗着し、注液口と封口栓の密閉性を高め溶接不良を低減させるという作用を有する。
【００１６】
請求項８に記載の発明は、電解液の注液口において封口栓嵌め込み側の周縁部上端を面取りしたものであり、密挿段部を有する封口栓の挿入を容易にし、特に封口栓挿入による溶接不良を低減させるという作用を有する。
【００１７】
以下、本発明の実施の形態について、図１から図４を用いて説明する。
（実施の形態１）
図１は本発明の請求項１記載の封口栓の密挿段部が樹脂製である封口栓の断面を示す。図１において、１は封口栓２の密挿段部で、封口栓を注液口に挿入した時の電解液の這い上がりを防止するもので、前記密挿段部１は樹脂から構成されている。樹脂としてはポリエチレン，ポリプロピレンやゴム等が使用でき、特に封口栓２をレーザー溶接するため、熱影響を考慮すると熱的に比較的安定で、また耐電解液性に優れた樹脂が好ましい。
【００１８】
（実施の形態２）
図２は本発明の請求項５記載の封口栓の断面を示す。図２において、３は金属製の封口栓で、電解液の這い上がりを減少させるために密挿段部４の径方向の寸法Ｃは注液口の壁面の径方向寸法に対して±０．１ｍｍである。本発明では、その寸法を±０．１ｍｍとすればよいが、より好ましくは０から±０．１ｍｍとし密挿段部４を注液口に圧入することにより、より密閉性が向上し、電解液の這い上がりを減少させることができる。また、その先端の形状は、このような圧入タイプの金属製の封口栓３を用いた場合でも挿入がスムーズに行われるように曲面としたものである。そして注液口壁面に接触する金属製の封口栓３の密挿段部４が接する部分５が０．１ｍｍ以上を確保できるように面取り、またはＲ形状としている。また、密挿段部４と鍔６とが連接する内周縁に凹部をつけることにより液だまり７をつくり、封口栓溶接部までの電解液の浸透を遅らせることができる。さらに、鍔６の下端の直線部８の寸法を０．３ｍｍ以上にすることにより、溶接時の熱影響を低下させることができる。本発明では、鍔６の下面の直線部８の寸法を０．３ｍｍ以上とすればよいが、金属製の封口栓３の材質等による溶接時のレーザー出力の違いにより、好ましくは０．５ｍｍ以上にする方がよい。
【００１９】
（実施の形態３）
図１および図２においてレーザー溶接部９は、レーザー出力をできるだけ弱くすることにより、注液口部分の熱影響を少なくし、電解液の上昇を減少させるためであり、薄肉部としたものである。
【００２０】
なお、以上の説明では、レーザー溶接部の薄肉部を注液口に嵌め込むための密挿段部を設けた封口栓で構成した例で説明したが、その他の封口栓でも同様に実施可能である。
【００２１】
また、図１および図２では薄肉部をＲ形状とした例で示したが、その他、面取りや段部等を設けても同様に実施可能である。
【００２２】
（実施の形態４）
図３はケース１０の開口部を封口した封口板１１の注液口１２に封口栓１３を挿入した断面を示したもので、図３において樹脂製の密挿段部１４と、注液口１２との密閉性を向上し、電解液の這い上がりを防止するために封止剤１５がある。
【００２３】
（実施の形態５）
図４は注液口部分の断面図であり、図４において、図１，２に示したような封口栓を用いた場合の栓挿入をスムーズにし、封口栓の浮きによる溶接不良を防止させるための面取り部１６を構成する目的で、注液口の周縁部上端を面取りする。面取りする寸法は、注液口壁面と封口栓密挿段部が０．１ｍｍ以上接する部分を確保できるようにすることが好ましい。
【００２４】
【実施例】
以下、本発明の実施例について図を用いて説明する。図５は、本発明の実施例における角形電池の断面図を示すもので、本発明を幅２２ｍｍ，高さ４８ｍｍ，厚み５ｍｍの薄型リチウムイオン二次電池に適用したものである。図５において、１７はアルミニウム製の角形ケースである。１８はアルミニウム製の封口板で、角形ケース１７とレーザー溶接されている。１９は極板群で、２０は正極リード、２１は負極リードである。２２は封口板１８に開けられた注液口で、２３は注液口２２を封止する封口栓である。
【００２５】
本発明の角形非水電解液電池は以下のようにして作製した。正極板は、活物質であるＬｉＣｏＯ₂に導電剤と結着剤を混合したものをアルミニウム箔の両面に塗着，乾燥し圧延した後、所定の大きさに切断したものとした。これにアルミニウム製の正極リード２０を溶接する。負極板は、炭素質材料を活物質とし、これと結着剤を混合したものを銅箔の両面に塗着，乾燥，圧延した後、所定の大きさに切断したものである。これに、ニッケル製の負極リード２１を溶接する。セパレータはポリエチレン製の微多孔フィルムである。正極板，負極板とをセパレータを介して巻回し、上面が長円形の極板群１９に整形する。極板群１９のリードを封口板１８に溶接し角形ケース１７に挿入し、封口板１８と角形ケース１７をレーザー溶接する。正極リード２０はアルミニウム製の封口板１８にレーザースポット溶接し、負極リード２１はニッケルメッキされた鉄製のワッシャー２４に抵抗溶接した。次に電解液を注液口２２から所定量注液する。電解液にはエチレンカーボネートとジエチルカーボネートを混合した溶媒に、溶質として六フッ化リン酸リチウムを溶解したものを用いた。その後、注液口２２に封口栓２３を施し、封口板１８と封口栓２３をレーザー溶接により封口した。なお図５において２５は安全弁、２６は樹脂製の絶縁性ガスケット、２７はニッケルメッキされた鉄製の端子をかねたリベットを示す。
【００２６】
（実施例１）
前述した封口栓について図を用いて説明する。本実施例１では、図１の（ａ）に示したような封口栓を用いた。図２において封口栓の密挿段部の樹脂は、本実施例ではエチレンプロピレンゴムを用いた。以上を実施例電池Ａとする。また、レーザー溶接部の薄肉部の効果を確認するため、実施例電池Ｂでは薄肉部を設けない封口栓を用いた。また、図２の（ａ）に示した封口栓を用いた実施例を実施例電池Ｃとする。実施例電池Ｃでは、図２において密挿段部の径方向の寸法を注液口の壁面間の寸法に対し＋０．１ｍｍとし、その先端周縁部分のＲを０．３ｍｍとし、液だまりのＲは０．０５ｍｍとした。さらに、鍔の直線部の寸法は０．５ｍｍのものを用いた。また、図３に示したように、注液口と封口栓との密閉性をよくするために、注液口の壁面に封止剤を塗着した。封止剤として本実施例ではコールタールピッチを用い、封口栓は実施例電池Ａのものを用いた。以上を実施例電池Ｄとする。これらの効果を確認するために、封口栓レーザー溶接時の電解液の付着によるレーザー溶接の穴あきによる不良率を比較した。その結果を表１に示す。また、従来品として注液口に対して封口栓の嵌め込み部分の寸法が０．２ｍｍ以下となるような封口栓を用いた。
【００２７】
【表１】

【００２８】
表１より明らかなように本発明の封口栓を用いた場合、従来用いられてきた封口栓に比較しレーザー溶接不良を飛躍的に低減することができる。また、実施例電池Ａと実施例電池Ｂを比較すると、レーザー溶接部に薄肉部を設けると、さらに効果的であることが分かる。さらに、実施例電池Ｄに示したように、封止剤により注液口と封口栓の密閉性をより向上させることにより、溶接不良を低減することができた。
【００２９】
また、本実施例では、樹脂としてエチレンプロピレンゴム、また封止剤にコールタールピッチを用いたが、その他の樹脂、また封止剤を用いても同様の結果が得られた。
【００３０】
（実施例２）
次に、電解液の注液口において封口栓嵌め込み側の周縁部上端を面取りした場合の利点を、図４を用いて説明する。図４に示したように電解液の注液口において封口栓嵌め込み側の周縁部上端を面取りすることによって、封口栓を注液口に挿入する際の挿入を容易にすることができる。本実施例では０．０５ｍｍの面取りを行い、封口栓は実施例電池Ａのものを用いた。以上を実施例電池Ｅとする。
【００３１】
本発明の効果を調べるために、注液口への封口栓挿入後の挿入不良率を表２に示す。本試験で用いた従来品は、実施例電池Ａに示した発明品を用いた。
【００３２】
【表２】

【００３３】
表２より明らかなように、特に本発明実施例１のような封口板を用いた場合は、本実施例のように電解液の注液口において封口栓嵌め込み側の周縁部上端を面取りすることによって、封口栓を注液口に挿入する際の挿入を容易にすることができ、封口栓の挿入不良を低減することができる。
【００３４】
なお、本実施例では角形リチウムイオン二次電池を用いた場合を示したが、他の電池系、例えばニッケルカドミウム二次電池，ニッケル水素二次電池，鉛蓄電池等に用いた場合にも同様の結果が得られた。さらに角形電池に限らず、このような注液口を持ち、注液を行った後、封口栓をし、封口板とを溶接するような電池の場合にも同様な結果が得られた。また、本実施例では電池ケースおよび封口栓の材質としてアルミニウムを用いたが、他の電池系においては、その材質に鉄，ステンレス等を用いて同様な好結果が得られた。
【００３５】
【発明の効果】
以上のように本発明によれば、密閉電池において注液口へ封口栓をレーザー溶接する際の溶接不良を低減し、信頼性を高めることができる。
【図面の簡単な説明】
【図１】本発明の実施の形態１における封口栓を示す断面図
【図２】同実施の形態２における封口栓を示す断面図
【図３】同実施の形態４における封口栓を注液口に嵌め込んだ封口栓部分の断面図
【図４】同実施の形態５における封口板注液口部分の断面図
【図５】本発明の実施例における角形電池の断面図
【図６】従来の封口栓の断面図
【符号の説明】
１，１４樹脂製の密挿段部
２，１３，２３封口栓
３金属製の封口栓
４密挿段部
６鍔
７液だまり
８直線部
９レーザー溶接部
１０ケース
１１，１８封口板
１２，２２注液口
１５封止剤
１６面取り部
１７角形ケース
１９極板群
２０正極リード
２１負極リード[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealed battery having a liquid inlet.
[0002]
[Prior art]
In recent years, various small secondary batteries have been used as power sources for driving portable devices. Conventionally, nickel cadmium batteries and nickel metal hydride batteries are used as such small secondary batteries, and in particular, lithium ion secondary batteries and the like are used.
[0003]
As a sealing method for such a sealed battery, there are a method in which the sealing plate and the case opening are sealed by laser welding, and a method in which the sealing plate is caulked with a case via a gasket.
[0004]
In particular, in the case of a battery in which the sealing plate and the case opening are sealed by laser welding as in the former, as a sealing method, first, liquid injection is performed, and then the sealing plate and the case opening are sealed by laser welding. In some cases, after sealing the sealing plate and the case opening, laser injection is performed from the sealing plate or from the liquid inlet of the battery case, and the sealing plug may be sealed. In particular, in the case of a battery in which the sealing plate and the case opening are laser welded to the latter and then the sealing plate or the battery case is used to inject the liquid into the sealing plug, the sealing plug and the sealing plate or the sealing plug are used. As shown in FIGS. 6 (a), 6 (b), and 6 (c) in Japanese Patent Application Laid-Open No. 9-288999, in order to provide a battery with high sealing performance by reducing welding defects when welding the battery case. In addition, a sealing plug shape in which a tightly-inserted step A that is entirely made of metal and is tightly inserted into a liquid injection port and a flange B that is laser-welded is integrated so that laser welding can be performed.
[0005]
[Problems to be solved by the invention]
When welding a conventional sealing plate and battery case and then injecting liquid from the inlet of the sealing plate or from the inlet of the battery case, and welding a sealing plug to the inlet, the cause of the increase in welding failure As a result, it is difficult to position the welding position, and when the sealing plug is inserted into the liquid injection port, the electrolytic solution creeps up, so that the electrolytic solution adheres to the vicinity of the welded portion or the electrolytic solution to the welded portion. Adhesion may cause perforation when welding the sealing plug. In particular, the conventional sealing plug shapes as shown in FIGS. 6A, 6B, and 6C have a problem in that the electrolytic solution adheres to the sealing plug to cause poor welding. Such poor welding reduces the sealing performance of the battery and causes leakage and productivity.
[0006]
In order to solve the above-described problems, an object of the present invention is to provide a highly reliable sealed battery that reduces defects during welding.
[0007]
[Means for Solving the Problems]
In order to solve this problem, the present invention uses a sealing plug made of resin for the sealing step of the sealing plug that is tightly inserted into the injection port, thereby improving the sealing property between the injection port and the sealing plug. It is configured to prevent the electrolyte from creeping up when the stopper is inserted, and to prevent the electrolyte from adhering to the welded part of the sealing stopper. As the dimensions match the dimensions of the wall surface, the electrolyte creeps up when the sealing plug is inserted, and a concave liquid puddle is formed on the inner periphery where the densely inserted step and the flange are connected. By delaying the permeation of the electrolytic solution to the welded portion and forming a straight portion on the lower surface of the flange portion, the influence of heat during welding is reduced.
[0008]
Thereby, the welding defect by adhesion of the electrolyte solution at the time of welding of a sealing plug is reduced, and a highly reliable sealed battery is obtained.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, the sealing step of the sealing plug that is tightly inserted into the injection port for the electrolyte is made of resin, or after inserting the resin plug, the metal sealing plug is It is inserted into a resin plug and has the effect of further enhancing the sealing properties of the liquid injection port and the sealing plug, preventing the electrolyte from rising, and reducing welding defects.
[0010]
The invention according to claim 2 is that the laser output can be weakened by providing a thin wall portion in the laser welded portion of the sealing plug, and the increase in the electrolyte is reduced by reducing the thermal effect up to the liquid injection port. Has an effect.
[0011]
In the invention according to claim 3, a sealing agent is applied between the tightly-inserted step portion of the sealing plug and the wall surface of the liquid injection port to improve the sealing property of the liquid injection port and the sealing plug, thereby preventing poor welding. It has the effect of reducing.
[0012]
The invention according to claim 4 is the one in which the upper end of the peripheral edge on the side where the sealing plug is inserted is chamfered at the electrolyte injection port, and facilitates the insertion of the sealing plug having a tightly inserted step, and particularly the insertion of the sealing plug. It has the effect of reducing welding defects due to.
[0013]
According to the fifth aspect of the present invention, the sealing plate is placed and welded to the upper opening of the battery case containing the electrode plate group, and electrolysis is performed from the liquid inlet of the sealing plate or the liquid inlet of the battery case. In a battery in which a sealing plug is fitted in the liquid inlet after sealing the liquid, the dimension in the radial direction of the tightly inserted step portion of the sealing plug is ± 0.1 mm with respect to the dimension between the wall surfaces of the liquid inlet. The tip has a curved surface to prevent the electrolyte from scooping up when the sealing plug is inserted, and a recess-shaped pool is formed on the inner periphery where the tightly-inserted stepped portion and the ridge are connected. The penetration of the liquid is delayed, and the lower surface of the collar portion is sealed with a sealing plug having a straight portion of 0.3 mm or more, and has the effects of reducing the influence of heat during welding and reducing welding defects.
[0014]
In the invention according to claim 6, the laser output can be weakened by providing a thin portion in the laser welded portion of the metal sealing plug, and the rise of the electrolyte is reduced by reducing the thermal effect up to the liquid injection port. It has the action.
[0015]
In the invention according to claim 7, a sealing agent is applied between the sealing plug having a metal close insertion step portion and the wall surface of the liquid injection port, thereby improving the sealing property of the liquid injection port and the sealing plug. It has the effect of reducing welding defects.
[0016]
The invention according to claim 8 is that the upper end of the peripheral portion on the side where the sealing plug is inserted is chamfered in the electrolyte injection port, and facilitates the insertion of the sealing plug having the tight insertion step portion, and particularly by insertion of the sealing plug. It has the effect of reducing welding defects.
[0017]
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
(Embodiment 1)
FIG. 1 shows a cross-section of a sealing plug in which the sealing step of the sealing plug according to claim 1 of the present invention is made of resin. In FIG. 1, reference numeral 1 denotes a tight insertion step portion of the sealing plug 2, which prevents the electrolyte from creeping up when the sealing plug is inserted into the liquid injection port. The tight insertion step portion 1 is made of resin. Yes. As the resin, polyethylene, polypropylene, rubber or the like can be used. Particularly, since the sealing plug 2 is laser-welded, a resin that is relatively thermally stable and excellent in electrolytic solution resistance is preferable in consideration of thermal effects.
[0018]
(Embodiment 2)
FIG. 2 shows a cross section of the sealing plug according to claim 5 of the present invention. In FIG. 2, 3 is a metal sealing plug, and the radial dimension C of the close insertion step 4 is ± 0. 1 mm. In the present invention, the dimension may be set to ± 0.1 mm, but more preferably from 0 to ± 0.1 mm, and the tight insertion step 4 is press-fitted into the liquid injection port, so that the sealing performance is further improved. Liquid creeping can be reduced. In addition, the shape of the tip is a curved surface so that the insertion can be performed smoothly even when such a press-fit type metal sealing plug 3 is used. And the chamfering or R shape is carried out so that the part 5 which the dense insertion step part 4 of the metal sealing plug 3 which contacts the liquid injection inlet wall surface can ensure 0.1 mm or more. Further, by forming a recess 7 on the inner peripheral edge where the densely inserted step 4 and the flange 6 are connected, the liquid pool 7 can be formed, and the permeation of the electrolytic solution up to the sealing plug weld can be delayed. Furthermore, the thermal influence at the time of welding can be reduced by making the dimension of the linear part 8 of the lower end of the collar 6 0.3 mm or more. In the present invention, the dimension of the straight portion 8 on the lower surface of the flange 6 may be 0.3 mm or more, but preferably 0.5 mm or more due to the difference in laser output during welding due to the material of the metal sealing plug 3 or the like. Better to do.
[0019]
(Embodiment 3)
In FIG. 1 and FIG. 2, the laser welding part 9 is to make the laser output as weak as possible, thereby reducing the thermal effect of the liquid injection port part and reducing the rise of the electrolyte, and is a thin part. .
[0020]
In the above description, an example in which the thin portion of the laser welded portion is configured with a sealing plug provided with a close insertion step for fitting into the liquid injection port has been described, but other sealing plugs can be similarly implemented. is there.
[0021]
1 and 2 show an example in which the thin-walled portion has an R shape, but the present invention can be similarly implemented by providing chamfering, a stepped portion, or the like.
[0022]
(Embodiment 4)
FIG. 3 shows a cross-section in which a sealing plug 13 is inserted into the liquid injection port 12 of the sealing plate 11 that seals the opening of the case 10. In FIG. 3, the resin-made close insertion step 14 and the liquid injection port 12 are shown. There is a sealant 15 for improving the sealing property and preventing the electrolyte from creeping up.
[0023]
(Embodiment 5)
FIG. 4 is a cross-sectional view of the liquid injection port. In FIG. 4, in order to smooth the plug insertion when the sealing plug as shown in FIGS. 1 and 2 is used, and to prevent welding failure due to the floating of the sealing plug. For the purpose of configuring the chamfered portion 16, the upper end of the peripheral edge of the liquid injection port is chamfered. The chamfer dimension is preferably such that a portion where the wall surface of the liquid injection port and the sealing plug tightly-inserted step portion are in contact with each other by 0.1 mm or more can be secured.
[0024]
【Example】
Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 shows a cross-sectional view of a prismatic battery according to an embodiment of the present invention, in which the present invention is applied to a thin lithium ion secondary battery having a width of 22 mm, a height of 48 mm, and a thickness of 5 mm. In FIG. 5, 17 is a square case made of aluminum. Reference numeral 18 denotes an aluminum sealing plate, which is laser-welded to the rectangular case 17. Reference numeral 19 denotes an electrode plate group, 20 denotes a positive electrode lead, and 21 denotes a negative electrode lead. 22 is a liquid injection port opened in the sealing

plate

18, and 23 is a sealing plug for sealing the liquid injection port 22.
[0025]
The rectangular nonaqueous electrolyte battery of the present invention was produced as follows. The positive electrode plate was obtained by applying a mixture of a conductive agent and a binder to LiCoO ₂ as an active material on both sides of an aluminum foil, drying and rolling, and then cutting into a predetermined size. An aluminum positive electrode lead 20 is welded thereto. The negative electrode plate is obtained by applying a carbonaceous material as an active material and mixing the binder and a binder onto both sides of a copper foil, drying and rolling, and then cutting the plate into a predetermined size. A nickel negative electrode lead 21 is welded thereto. The separator is a microporous film made of polyethylene. The positive electrode plate and the negative electrode plate are wound through a separator and shaped into an electrode plate group 19 having an oval upper surface. The lead of the electrode plate group 19 is welded to the sealing plate 18 and inserted into the rectangular case 17, and the sealing plate 18 and the rectangular case 17 are laser welded. The positive electrode lead 20 was laser spot welded to the sealing plate 18 made of aluminum, and the negative electrode lead 21 was resistance welded to an iron washer 24 plated with nickel. Next, a predetermined amount of electrolyte is injected from the injection port 22. As the electrolytic solution, a solution obtained by dissolving lithium hexafluorophosphate as a solute in a solvent obtained by mixing ethylene carbonate and diethyl carbonate was used. Thereafter, a sealing plug 23 was applied to the liquid injection port 22, and the sealing plate 18 and the sealing plug 23 were sealed by laser welding. In FIG. 5, 25 is a safety valve, 26 is a resin insulating gasket, and 27 is a rivet that also serves as a nickel-plated iron terminal.
[0026]
(Example 1)
The sealing plug described above will be described with reference to the drawings. In Example 1, a sealing plug as shown in FIG. 1A was used. In FIG. 2, ethylene propylene rubber was used as the resin at the close insertion step portion of the sealing plug in this example. The above is referred to as Example Battery A. Moreover, in order to confirm the effect of the thin part of a laser weld part, the sealing plug which does not provide a thin part was used in Example battery B. In addition, an example using the sealing plug shown in FIG. In Example Battery C, the radial dimension of the densely inserted step in FIG. 2 is +0.1 mm with respect to the dimension between the wall surfaces of the liquid inlet, and R at the peripheral edge of the tip is 0.3 mm. Was 0.05 mm. Furthermore, the dimension of the linear part of the collar was 0.5 mm. Further, as shown in FIG. 3, a sealing agent was applied to the wall surface of the liquid injection port in order to improve the sealing property between the liquid injection port and the sealing plug. In this example, coal tar pitch was used as the sealant, and the sealing plug of Example Battery A was used. The above is referred to as Example Battery D. In order to confirm these effects, the defect rates due to laser welding holes due to the adhesion of electrolyte during sealing plug laser welding were compared. The results are shown in Table 1. Further, as a conventional product, a sealing plug was used in which the dimension of the fitting portion of the sealing plug with respect to the liquid injection port was 0.2 mm or less.
[0027]
[Table 1]

[0028]
As is apparent from Table 1, when the sealing plug of the present invention is used, laser welding defects can be dramatically reduced as compared with conventionally used sealing plugs. In addition, when Example Battery A and Example Battery B are compared, it can be seen that it is more effective to provide a thin portion in the laser welded portion. Furthermore, as shown in Example Battery D, it was possible to reduce welding defects by further improving the sealing properties of the liquid injection port and the sealing plug with the sealant.
[0029]
In this example, ethylene propylene rubber was used as the resin, and coal tar pitch was used as the sealant. However, similar results were obtained using other resins and sealants.
[0030]
(Example 2)
Next, the advantage of chamfering the upper end of the peripheral edge on the sealing plug insertion side in the electrolyte injection port will be described with reference to FIG. As shown in FIG. 4, by chamfering the upper end of the peripheral portion on the sealing plug insertion side in the electrolyte injection port, insertion when the sealing plug is inserted into the injection port can be facilitated. In this example, chamfering of 0.05 mm was performed, and the sealing plug of Example Battery A was used. The above is referred to as Example Battery E.
[0031]
In order to examine the effect of the present invention, the insertion failure rate after inserting the sealing plug into the liquid inlet is shown in Table 2. The conventional product used in this test was the product shown in Example Battery A.
[0032]
[Table 2]

[0033]
As is clear from Table 2, particularly when a sealing plate such as Example 1 of the present invention is used, the upper end of the peripheral edge on the side where the sealing plug is inserted is chamfered at the electrolyte injection port as in this Example. Therefore, it is possible to facilitate insertion when the sealing plug is inserted into the liquid injection port, and it is possible to reduce poor insertion of the sealing plug.
[0034]
In addition, although the case where the square lithium ion secondary battery was used was shown in the present embodiment, the same applies to the case where it is used for other battery systems such as nickel cadmium secondary batteries, nickel hydride secondary batteries, lead storage batteries, etc. Results were obtained. Furthermore, the present invention is not limited to the rectangular battery, and similar results were obtained in the case of a battery having such a liquid injection port, injecting the liquid, sealing the plug, and welding the sealing plate. In this example, aluminum was used as the material for the battery case and the sealing plug. However, in other battery systems, similar results were obtained using iron, stainless steel, or the like as the material.
[0035]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce welding defects when laser-sealing a sealing plug to a liquid inlet in a sealed battery, and to improve reliability.
[Brief description of the drawings]
1 is a cross-sectional view showing a sealing plug in Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view showing a sealing plug in Embodiment 2. FIG. 3 is a liquid injection port with the sealing plug in Embodiment 4. FIG. 4 is a cross-sectional view of a sealing plate liquid inlet portion in the fifth embodiment. FIG. 5 is a cross-sectional view of a prismatic battery in an example of the present invention. Cross section of sealing plug [Explanation of symbols]
1,14 Resin-made densely inserted

step portions

2, 13, 23 Seal plug 3 Metal-made seal plug 4 Closely inserted step portion 6 鍔 7 Puddle 8 Straight portion 9 Laser welded portion 10

Cases

11, 18

Sealing plates

12, 22 Injection port 15 Sealing agent 16 Chamfer 17 Square case 19 Electrode group 20 Positive electrode lead 21 Negative electrode lead

Claims

The sealing plate is placed and welded to the upper opening of the battery case containing the electrode plate group, and the liquid injection is performed after injecting the electrolyte from the liquid inlet of the sealing plate or the liquid inlet of the battery case. A sealed battery in which a sealing plug having a resin close insertion step portion matching the wall surface of the mouth is fitted into the liquid injection port, and the liquid injection port and the sealing plug are sealed by laser welding.

The sealed battery according to claim 1, wherein a thin-walled portion is provided in a laser welded portion of the sealing plug.

The sealed battery according to claim 1, wherein a sealing agent is applied between a resin-made close insertion step portion of the sealing plug and a wall surface of the liquid injection port.

The sealed battery according to claim 1, wherein the upper end of the peripheral edge on the side where the sealing plug is fitted is chamfered in the electrolyte injection port.

The sealing plate is placed and welded to the upper opening of the battery case containing the electrode plate group, and the liquid injection is performed after injecting the electrolyte from the liquid inlet of the sealing plate or the liquid inlet of the battery case. In a battery that is sealed by fitting a metal sealing plug into the mouth, the radial dimension of the tightly inserted step portion of the sealing plug is ± 0.1 mm with respect to the radial dimension of the wall surface of the liquid inlet, Is a curved surface, and a recessed portion is formed on the inner peripheral edge where the densely inserted step and the flange are connected, and the bottom surface of the flange is sealed with a metal sealing plug having a straight portion of 0.3 mm or more. battery.

The sealed battery according to claim 5, wherein a thin-walled portion is provided in a laser welded portion of the metal sealing plug.

6. The sealed battery according to claim 5, wherein a sealing agent is applied between a sealing plug having a metal close insertion step and a wall surface of the liquid injection port.

The sealed battery according to claim 5, wherein the upper end of the peripheral edge on the side where the sealing plug is fitted is chamfered at the electrolyte inlet.