JPH0557705B2

JPH0557705B2 -

Info

Publication number: JPH0557705B2
Application number: JP61139619A
Authority: JP
Inventors: Nobuo Kamata; Kazutoshi Takeda; Iwao Kishi; Toyoro Harada; Hiroaki Aihara; Tatsuo Arakawa
Original assignee: Seiko Electronic Components Ltd
Current assignee: Seiko Electronic Components Ltd
Priority date: 1986-06-16
Filing date: 1986-06-16
Publication date: 1993-08-24
Also published as: JPS62296361A

Description

[Detailed description of the invention]

〔産業上の利用分野〕本発明は平板型電池に関し、さらに詳しくはシ
ール性を大幅に改善した長期信頼性に優れる平板
型電池に関するものである。また、電池の内部及び外周部でのシヨートを防
止した平板型電池に関するものである。さらに、
長期間の保存もしくは使用に当たつても電池のフ
クラミの少ない安定した平板型電池に関するもの
である。〔発明の概要〕本発明は、外装を兼ねる正極端子板と負極端子
板との間に発電要素を収納し、この正、負極端子
板の周縁を封口材で密封した平板型リチウム電池
であつて、前記封口材としてマレイン酸変性ポリ
エチレン樹脂／高密度ポリエチレン樹脂／マレイ
ン酸変性ポリエチレン樹脂から構成された二種三
層ラミネートフイルムを用いることにより、電池
のシール性を大幅に向上させたものである。また、この封口材を予め正極端子板、負極端子
板へ熱溶着させておくことにより、電池内に充填
される発電要素をヒートシール時の熱により劣化
せしめることなく、確実にヒートシールによりシ
ールすることができるものである。さらに、２枚のポリプロピレン不織布を重ねて
圧延されたセパレータを用いて、かつそのセパレ
ータの周縁部を前記封口材にて挟持し固定し、セ
パレータを介しこのシヨートやセパレータ外周部
でのシヨートを防止しようとするものである。正極端子板と負極端子板の外形寸法を変えるこ
とにより、ヒートシール時と電池外形仕上げ抜き
時の正極と負極間のシヨートを防止するものであ
る。ヒートシール後、封口材のハミ出した部分を
取り除くために電池外形仕上げ抜きを施すことに
より、電池外形寸法を所定のものとするものであ
る。正極合剤シートを予め電解液と反応させて、
この反応処理された正極合剤シートを電池の正極
活物質として使用することにより、電池保存中も
しくは使用中のガス発生による電池フクラミの防
止を図るものである。予め絞り加工された正極端子板もしくは負極端
子板を用いることにより、電池発電要素の電池内
での位置合せが容易に行えるとともに、位置ズレ
が防止できる。電池製造後、この電池の理論容量の５％程度を
放電させてから電池を保存したり、使用すること
により、電池保存もしくは使用中の電池フクラミ
量を小さく抑えるものである。電池製造後、この電池を放電させてその電池の
開路電圧を3.0〜3.1Vに設定することにより、電
池保存もしくは使用中の電池フクラミ量を小さく
抑えるものである。〔従来の技術〕従来、正極集電板を兼ねる封口板と負極集電板
を兼ねる封口板との間に発電要素を収納し、封口
板の周縁を絶縁材で密封した扁平形電池であつ
て、前記絶縁材として無水マレイン酸変性ポリエ
チレン樹脂を用いた扁平形電池が知られていた。また、セパレータにポリプロピレン不織布を用
い、このセパレータ周縁部を固定しない方法が知
られていた。無水マレイン酸変性ポリエチレン樹脂と封口板
との接着方法は、熱板圧着法、インパルス接着
法、超音波接着法のいずれでもよく、例えば、熱
板圧着法の場合、温度190℃で３〜10Kg／cm²の圧
力を３〜５秒加えることによつて接着できること
が知られていた。さらに、正極封口板と負極封口板のサイズが同
一であることが知られていた。特開昭59−83340号公報にこのような従来の電
池が開示されている。〔発明が解決しようとする問題点〕従来の電池は封口材として、無水マレイン酸変
性ポリエチレン樹脂一層品を用いているので、電
池周辺部を熱と圧力にてヒートシールする際に、
封口材が電池周辺部の外へ食み出し過ぎて、正極
端子板と負極端子板の間でシヨートする欠点があ
つた。このシヨートする原因は封口材が融点もし
くは融点以上に加熱されながら加圧されるので、
封口材の流動性が増して電池周辺部に漏れ出て正
極端子板と負極端子板間に介在する封口材の量が
少なくなるためである。また、ヒートシール時の
圧力が不均一であつたり、正、負極端子板の外周
部に打抜バリ等の突起物があつたりすれば正、負
極同志が接することになりシヨート状態となる。
さらに、この封口材の量の多い部分と少ない部分
は、正、負極端子板と封口材とのよく密着した部
分と悪い密着部分とを形成することになる。この悪い密着部分はシール不良となり、電池外
部から空気や湿気が電池内に侵入し、負極リチウ
ムを劣化せしめる欠点があつた。また、このようにヒートシール性を有する樹脂
単体を用いると、電池外周のヒートシール部分の
厚みを一定に仕上げることが困難である欠点があ
つた。そこで、この発明は従来のこのような欠点を解
決することにより、薄くて、シール性が大幅に改
善された長期信頼性に優れる平板型リチウム電池
を得ることを目的としている。セパレータの周縁部と封口材が固定されていな
いので、セパレータ、正極合剤、負極のリチウム
シートが位置ズレを起こして正極合剤とリチウム
との接触によるシヨート、正極合剤と負極封口板
との接触によるシヨート、リチウムと正極封口板
との接触によるシヨートのいずれかによるシヨー
トが発生する欠点があつた。正極封口板と負極封口板の外形寸法が同一なの
でヒートシール時にシヨートしたり、封口材に用
いる樹脂がハミ出して外形寸法が所定の寸法より
大きくなつたりする欠点があつた。そこで、この発明は従来のこのような欠点を解
決することにより、電池組立時のヒートシール時
のシヨートや電池使用中もしくは保存中のシヨー
トを防止することを目的としている。〔問題点を解決するための手段〕上記問題点を解決するためにこの発明は、外装
を兼ねる正極端子板と負極端子板との間に発電要
素を収納し、この正、負極端子板の周縁を封口材
で密封した平板型リチウム電池であつて、前記封
口材としてマレイン酸変性ポリエチレン樹脂／高
密度ポリエチレン樹脂／マレイン酸変性ポリエチ
レン樹脂から構成された二種三層ラミネートフイ
ルムを用いることにより、さらに、この封口材を
正極端子板側に１枚、負極端子板側に１枚を重ね
て配設することにより電池のシール性を大幅に向
上せしめ、外部からの空気、水分の侵入を遮断し
たので、長期信頼性の優れた平板型リチウム電池
が実現できた。また、ヒートシール時のシヨートを防止すると
ともに、ヒートシール部の厚みを均一にすること
ができ、より信頼性の高い電池を提供することが
できた。〔作用〕本発明者は封口材の構成と樹脂について鋭意研
究した。マレイン酸変性ポリエチレン樹脂は中密
度ポリエチレンにマレイン酸をグラフト重合した
ものである。このマレイン酸のグラフト率は0.05
〜0.2％が最適である。このグラフト率が0.2％以
上になると水分の透過性が増加するのでリチウム
電池の封口材としては不適である。一方、0.05％
以下になると金属からなる正、負極端子板との接
着性が乏しくなり、封口材として機能しなくな
る。このマレイン酸変性ポリエチレンフイルムは
厚みが30±5μ、mp120℃、メルト・インデクス
0.3、密度0.91である。また、このフイルムの厚
みは薄くなり過ぎればヒートシール時に、樹脂が
流動して電池シール部外へ流出することがあるの
で、シール不良の発生が多くなる。実験では20μ
が最低必要厚みである。一方、このフイルムの厚
みが厚くなり過ぎれば、ヒートシール時の熱と圧
力による樹脂の流出を差し引いても充分この樹脂
のシールにあずかるが、電池外部からの水分侵入
に対しては得策ではない。この理由はマレイン酸
をグラフトしたポリエチレンは金属との接着性は
向上するが、マレイン酸をグラフトしないポリエ
チレンに比べて水分の透過性が増加するからであ
る。要はヒートシール部の厚みを均一にすることと
シール性を確保する上から、必要最小限の厚みに
することが大切である。次に、高密度ポリエチレンフイルムについて説
明する。この高密度ポリエチレンフイルムはマレ
イン酸をグラフトしていないフイルムなので金属
との接着性はなく、正、負極端子間の距離、すな
わち電池シール部の厚みを一定のものとするため
のスペーサの役割を果している。このフイルムの厚みは電池の厚みに応じて任意
に設定できるものである。本発明の実施例では電
池の厚みが0.5mmなので、フイルムの厚みは50〜
200μが適当である。また、フイルムはmp129℃、メルト・インデク
ス0.6、密度0.95である。メルト・インデクスは樹脂の流動性を示す指数
で、数字が大きい程流動性が乏しいことを示して
いる。すなわち、この高密度ポリエチレンはマレ
イン酸変性ポリエチレンと同じポリエチレンと言
うことで熱溶融するので、この接合面からの水分
侵入は問題なく、mpもマレイン酸変性ポリエチ
レンに比べて９℃高い上に流動性も少ないので、
良好なスペーサとなり得る。さらに、マレイン酸
がグラフトされていないので、水分透過性も少な
く良好な封口材にもなり得るものである。次に、本発明は封口材として二種三層ラミネー
トフイルム、すなわちマレイン酸変性ポリエチレ
ン／高密度ポリエチレン／マレイン酸変性ポリエ
チレンを用いている理由を説明する。この理由の一つは、フイルム表裏がないので、
接着層面（マレイン酸変性ポリエチレン面）と非
接着層面（高密度ポリエチレン面）の判別をする
必要がない。もつ一つの理由は予め正極端子板、負極端子板
にこの封口材を溶着しておけば、電池発電要素を
充填したのちヒートシールする際、高密度ポリエ
チレン同志を接着するよりはmpも低く接着性に
富むマレイン酸変性ポリエチレン同志を接着する
法が容易にかつ確実にシールできる。また、ヒートシール温度も低く、かつ短時間で
シールが可能となり、リチウム電池内のリチウ
ム、有機電解液、セパレータ、正極活物質に対し
て熱による損傷、劣化を少なくできる。本発明の封口材である二種三層ラミネートフイ
ルムをインフレーシヨン方式で製造することが最
適であり、この方式による二種三層ラミネートフ
イルムを用いると電池の封口部でのシール性が向
上する理由について説明する。一般にフイルム製造方法として(1)Ｔダイ方式と
(2)インフレーシヨン方式がある。Ｔダイ方式は廉
価にフイルムを製造できるので広く普及している
が、一軸延伸のため熱を加えると長さ方向と幅方
向で熱収縮率と熱膨張率が相違するので、このフ
イルムを封口材に用いると方向により、シール幅
が異なる欠点を持つている。当然、シール幅が狭
くなつた法がシール性が悪くなる。一方、インフレーシヨン方式は高価なフイルム
の製造法であるが、二軸延伸のため熱を加えて冷
却しても熱収縮率、熱膨張率に等方性がある。よつて、このフイルムのいかなる場所のシール
幅も同一にできる。ことことにより、封口材の幅
とシール幅が均一にコントロール可能となる。本発明の封口材を予め正、負極端子板に熱溶着
する理由について説明する。本発明者も最初、正極端子板の上に封口材枠を
載置し、枠内に正極活物質、セパレータを順次載
置し、内側にリチウムを配した負極端子板を重ね
て被せたのち、電池外周部をヒートシールしよう
と試みたがシールが出来なかつた。この原因は正、負極端子板がニツケルとかステ
ンレスなどの金属であるため、ヒートシール時の
熱が逸散するためである。さらに、電池内容物が
入つているため、よりヒートシール時の熱が伝熱
し、吸収されてしまうためである。それでもなおヒートシールしようと思えば、ヒ
ートシールの温度を高くしたり、加圧時間を長く
すれば良いが、電池内容物が必要以上に加熱され
たり、端子板と封口材の熱膨張率と熱収縮率が異
なるので電池外周のヒートシール部に皺が発生し
たり電池全体が反つたりする現象が生じ不都合で
ある。本発明は正、負極端子板に予め本発明に係る封
口材を熱溶着しておく訳である。このようにしておけば、mp170℃のリチウムを
溶解させたり、有機電解液を熱分解させたりする
必要がない。すなわち、熱や圧力、時間を溶着に必要な分だ
け十分に加えることができるので、正、負極端子
板と封口材との接着性は完全なものとなる。本発明の場合も電池内容物を充填したのち、ヒ
ートシールによつて電池外周部をシールする訳で
あるが、同一材質の封口材同志の接着だから容易
にシールができる。また、この正、負極端子板と封口材の溶着も直
接１回では出来ない。本発明はまず、正、負極端子板と正、負極封口
材を各々位置を合わせながら重ねて160℃、圧力
２Kg／cm²、３秒間熱プレスして仮溶着する。この時点では封口材は正、負極端子板に弱く接
着している程度である。この後、封口材が仮溶着され正、負極端子板は
200℃、10分間熱処理されて完全に封口材と正、
負極端子板が溶着することになる。本発明はセパレータとして目付量20ｇ／m²のポ
リプロピレン不織布を２枚重ねて圧延したものを
使用している。圧延前のポリプロピレン不織布は
厚みが60μであり、これを２枚重ねされた圧延し
て総厚み80μに加工している。この２枚重ねた圧
延セパレータは目付量が40ｇ／m²である。また、
圧延前の不織布はマイクロスパンボンド紡糸方式
により製造されており、アニオン界面活性剤を含
浸している。もし、この界面活性剤が含浸されて
いなければ、ポリプロピレン不織布はプロピレン
カーボネート等からなる有機電解液に対して濡れ
性が乏しく電池内部抵抗が大きくなる欠点があ
る。このように本発明が特殊加工したセパレータを
使用している理由は電池の上下を強く押圧したと
き、負極活物質のリチウムと正極活物質とがセパ
レータを貫通してシヨートすることも防止してい
る。第６図は各種セパレータを用いて電池の上下に
10Kg／cm²の外部圧力を加えながら、電池を80℃、
湿度RH90〜95％下に保存したときの開路電圧を
測定したグラフである。図中、○は本発明に係る
セパレータ、□は厚み120μ、目付量37ｇ／m²の
ポリプロピレン不織布、△は厚み50μ、目付量20
ｇ／m²の一層品でポリプロピレン不織布である。本発明電池の厚みは0.5mmであるから、電池容
量を大きくするためにもセパレータの厚みを出来
る限り薄くする必要がある。一層品セパレータは
厚み50μではセパレータを通してシヨートしてし
まう。一方、セパレータ厚み120μではセパレー
タを通してシヨートしないが、厚みが厚いので本
発明電池には不適当である。本発明に係るセパレータがシヨート防止に効果
を発揮する理由は目付量の大きい不織布を２枚重
ねて圧延しているのでセパレータに貫通孔（ピン
ポール）が存在せず迂回した通路が形成されてい
るためである。また、２枚のセパレータを重ねる
ことにより孔と孔とがズレるのでさらにストレー
トな貫通孔は皆無になつているからである。また、セパレータをさらに薄くする目的で厚み
25μの微孔性ポリプロピレンフイルムや厚み10〜
50μのコンデンサーペーパーを使用したが、電池
内部抵抗が数kΩと高く本発明電池には使用でき
ない。この内部抵抗が大きくなる理由は本発明電
池では極く微少量の電解液しか電池内に充填する
ことしかできないので、セパレータが十分濡れる
ことがないためである。本発明電池は第１図に示すように、セパレータ
周辺部を正、負極封口材の間に挟持している。セパレータの材質がポリプロピレンで封口材の
材質がポリエチレンであるのでヒートシールの
際、この両者が熱溶着し、固定されることにな
る。このようにセパレータ周辺部を封口材との間で
固定することにより、電池を長期間保存したり、
使用したりしている間に正極活物質が粉こぼれし
ても負極活物質であるリチウム側への泳動による
リチウム劣化が防止できる。また、正極活物質や負極活物質が位置ズレを起
こしても正極活物質と負極活物質との接触を防止
できる。特に、この本発明電池が屈曲されたときに、本
発明は効果を発揮する。本発明が電池外周部をヒートシールして電池組
立後、所定寸法に電池を仕上げるため外形抜きを
施している理由について説明する。第５図は従来の外形仕上げ抜を施していない電
池周辺部の断面図である。図中、１は予め所定寸法に裁断された正極端子
板、２は正極封口材、６は予め所定寸法に裁断さ
れた負極端子板、７は負極封口材である。この図のように、電池外周部をヒートシールに
封口する際どうしても封口材が所定電池サイズの
外へ流出、ハミ出してしまう欠点がある。すなわち、所定電池形状と異なつたり、サイズ
もハミ出した分だけ大きく電池が仕上がつてしま
うことになる。そこで本発明は正極端子板、負極端子板のいず
れか一方を十分にサイズを大きくしておき、ヒー
トシールして電池組立後に所定寸法に電池外形仕
上げ抜を施すことにある。第３図、第４図は本発明の一実施例を示す図で
ある。第３図、第４図は負極端子板に比べて正極
端子板の方を大きく設定した例にて説明してい
る。第３図は本発明を適用した電池の外形仕上げ
抜前後の平面図と断面図である。図中、電池Ａは電池組立直後の形状で、未だ外
形仕上げ抜は施されていない。電池Ｂは電池Ａの
外形を所定寸法に仕上げ抜してある。第４図は第３図の電池Ａ，Ｂの外周部拡大図で
ある。図中、１は正極端子板、２は正極封口材、６は
負極端子板、７は負極封口材である。電池Ａをカツト線Ｃで裁断すれば所定寸法の電
池Ｂが得られることになる。また、電池Ａの正極端子板１のサイズは正極封
口材２、負極封口材７のハミ出し部より大きく設
定されていればよい。このように封口材２，７のハミ出し部より正極
端子板１のサイズを大きくしておけば、この正極
端子板１の外形により位置決めが可能となり、所
定寸法に外形仕上げ抜できる。また、電池ＡとＢの正極端子板１の寸法差l₁は
２mm以上あれば適当である。しかし、この寸法差
l₁をあまり大きく過ぎれば、切り捨ててしまう電
池Ａの正極端子板１の材料費が勿体ないことにな
る。本発明が正極端子板１と負極端子板６の外形寸
法を変えている理由について説明する。この理由の１つは電池封口するためヒートシー
ル際に、正極端子板１と負極端子板６がシヨート
しないようにするためである。このシヨート発生
のメカニズムはヒートシール時に電池の最外周端
部に最も一番圧力が加わる上に、正極端子板１と
負極端子板６の加工プレスバリが発生しているか
らである。２つ目の理由は電池外形仕上げ抜する際、正極
端子板１と負極端子板６を同時に打抜いてしまう
と打抜バリにより正極端子板１と負極端子板６と
か接触してシヨートになるからである。このように、正極端子板１と負極端子板６の寸
法を変えておくことにより、ヒートシール時のシ
ヨート及び外形仕上げ抜時のシヨートを防止する
ことができる。本発明が正極活物質を予め電解液と反応させて
おく理由について説明する。従来より、エチレンカーボネートとMnO₂とが
反応してCO₂ガスを発生することは知られてい
る。例えば、Blomgren、G.E.（1983）、“Lithium
Batteries”（J.P.Gabano、ed.）、P22、
Academic Press、New York and London.に、
以下の反応式が記載されている。本発明は本発明に係る正極合剤シートを１モル
Liclo₄を含むプロピレンカーボネート（PC）か
らなる電解液との反応条件を適切にすることによ
り、MnO₂と電解液との反応によるガス発生を防
止するものである。第８図は正極合剤シートと電解液との反応温
度、反応時間での電池フクラミ量を示す図であ
る。第８図に用いた電池は正極合剤シートを80℃、
100℃、120℃で各々3Hrおよび15Hr電解液中で
処理したのち、この正極合剤シートを電解液中か
ら取出して電池内にセパレータ４、電解液と共に
封入した。図中、Ａは15Hr処理した場合で、Ｂ
は3Hr処理した場合である。この電池を80℃、相対湿度（RH）90％の恒温
恒湿槽内で５日間保存したのち、保存前後の電池
厚み差を求め、これを電池フクラミ量とした。こ
の電池フクラミ量の単位は１＝0.01mmである。この第８図より、温度100℃以上が望ましい。
また、時間は3Hrより15Hrの方が望ましい。実用的には、100℃、15Hr、120℃、15Hrの条
件で適切である。このように、正極合剤シートと電解液とを予め
反応させる効果は正極合剤シート中のMnO₂が電
解液と反応することによりMnO₂の活性な部分が
失活するものと推定される。本発明の反応条件であればMnO₂の電気容量を
減じることもないので、電池容量が減少するよう
なこともない。 140℃以上での反応では電池の容量が減少して
しまう欠点を有している。本発明が本発明電池組立後に放電処理を施す理
由について説明する。第７表は本発明電池を種々な放電電流と放電時
間で処理したときの開路電圧（Voc）、内部抵抗
（Ri）及び電池フクラミ量を示した表である。電池フクラミ量は電池を種々な条件で放電させ
たのち、80℃、RH90％下で保存し、５日枚に保
存前後の電池厚み差を調べた。この第７表より明らかなように、放電電流は20
ｍＡが一番フクラミ量を小さく抑える上で効果が
大きく、放電時間は２分より６分の方が電池フク
ラミ量を小さくする上で効果がある。このように放電電流を大きくまた放電時間を長
くすれば電池のフクラミ量は小さくなる。本発明者は80℃、RH90％で５日保存すること
は25℃、１年保存に相当すると推定しているので
15日すなわち25℃、３年間保存で電池フクラミ量
が５以内を満足するためには20ｍmA×６分以上
の条件が適当である。この20ｍＡで６分間電池を放電すると、このこ
とによる放電量は２ｍAhとなり、本発明による
リチウム平板型電池の一実施例であるcs2328（開
路電圧3V、公称容量30ｍAh、23×28×0.5mm）の
理論電池容量の5.2％に相当する。この放電量をより多くすれば正極合剤シート中
のMnO₂が安定して電解液との反応によるCO₂発
生も少なくなるものと推定されるが、あまり多く
放電すれば電池容量も減少してしまう欠点が有し
ている。従つて、この放電処理量と電池フクラミ量は適
切にバランスさせる必要がある。以上詳述したように、封口材としてマレイン酸
変性ポリエチレンと高密度ポリエチレン樹脂から
なる二種三層ラミネートフイルムを用い、この封
口材を予め正極端子板と負極端子板に熱溶着させ
ておくことにより、ヒートシールを容易かつ確実
に行わしめるとともにシール性を大幅に向上せし
めることができた。目付量20ｇ／m²のポリプロピレン不織布を２枚
重ねて圧延一体化したセパレータを使用し、かつ
このセパレータの外周部を前記封口材にて挟持、
固定することにより、電池内部でのシヨートを防
止せしめることができた。絞り形状の角隅部に３mm以上のＲ部を有する絞
り加工を施した正極端子板もしくは負極端子板を
用いることによつて、シール性を大幅に改善せし
めるとともに、リチウム、セパレータ、正極合剤
シートなどの発電要素の載置する際の位置合せガ
イドを提供し、位置ズレ防止を図ることができ
た。正、負極端子板の外形寸法を変えておくことに
より、ヒートシール時のシヨートと電池外形仕上
げ抜時のシヨートを防止せしめることができる。電池外形仕上げ抜を施すことにより、電池外形
寸法を所定の寸法に美麗さを損なうことなくする
ことができた。正極合剤シートを電解液で処理したのち、この
正極合剤シートを電池に組込むことにより、電池
の保存もしくは使用中における電池の膨らみを少
なくせしめることができた。電池製造後、電池を放電処理することにより、
電池の保存もしくは使用中における電池の膨らみ
を少なくせしめることができた。〔実施例〕以下に本発明の実施例を図面に基づいて説明す
る。実施例１第１図は本発明を適用した平板型リチウム電池
の一実施例である。まず、サイズ23×28×0.5mm（CS2328、
Voc3V、公称容量30ｍAh）について説明する。図中、１は正極端子板で、SUS430、
SHOMAC30−２などからなり厚み30μである。
第１図、第２図、第３図に示すように、この正極
端子板は予め絞り加工されている。第３図に示す
通り、Ｒ部は３mm以上で、絞り深さｄは0.16〜
0.22mmである。また、正極端子板の外形寸法は27×32mmであ
る。この正極端子板１の内側に二酸化マンガンを主
体とする正極合剤シート３が挿入、載置されてい
る。次いで、正極合剤３の上にセパレータ４を載
置している。また、この正極合剤シート３は電池内に組込ま
れる前に、予め電解液で処理される。この処理方
法はこの正極合剤シート３をｎ＝100個用意し、
１モルLiclO₄／プロピレンカーボネート（PC）
からなる電解液50c.c.に浸漬し、密栓をしたのち、
120℃、15Hr間加熱する。この加熱後、この正極
合剤シートを取出して、新しい電解液50c.c.に室温
で、30分以上浸漬し、正極合剤シート中に含有さ
れている旧い電解液を新しい電解液へ置換する。この新しい電解液で処理された正極合剤シート
を取り出して電池の正極活物質として使用する。この電解液と処理されるMnO₂理論容量の関係
は処理されるMnO₂の理論容量／必要な電解液量
＝30〜100ｍAh／c.c.となる。このセパレータ４は目付量20ｇ／m²のポリプロ
ピレン不織布を２枚重ねて圧延一体化したもので
ある。また、このセパレータ４の外周部は封口材
２と７の間に挟持されて固定されている。さら
に、電池外周部をヒートシールする際、このセパ
レータ４の外周部も封口材２と７に溶着し、さら
に確実に固定されることになる。５は負極活物質であるリチウムで、負極端子板
６の内側に圧着されている。この負極端子板６は
ニツケル、アルミニウム、ステンレス等からな
り、外形寸法は22×27mmで厚みは30μである。第
２図は本発明に係る封口材の詳細断面図である。
図中２ａ，７ａはマレイン酸変性ポリエチレン、
２ｂ，７ｂは高密度ポリエチレンである。２は予め正極端子板１の外周内面に溶着された
正極封口材で、マレイン酸変性ポリエチレン／高
密度ポリエチレン／マレイン酸変性ポリエチレン
の二種三層ラミネートでインフレーシヨン方式に
て製造されたフイルムである。７は予め負極端子板６の外周内面に溶着された
負極封口材で、マレイン酸変性ポリエチレン／高
密度ポリエチレン／マレイン酸変性ポリエチレン
の二種三層ラミネートでインフレーシヨン方式に
て製造されたフイルムである。この封口材２と７の厚み構成はマレイン酸変性
ポリエチレン２ａ，７ａが30±5μで、高密度ポ
リエチレン２ｂ，７ｂが60±5μである。また、この封口材２と７を各々正極端子板１と
負極端子板６の外周内面に予め溶着するのは次の
ようにする。正極端子板１と正極封口材２（外寸法23×28
mm、内寸法16、６×21、６mm）を位置がズレない
ように合わせて重ね、この正極端子板１の方から
熱板を圧着する。このときの温度は160±10℃で
圧力は２±0.5Kg／cm²、加圧時間は３〜５秒であ
る。このように正極端子板１と正極封口板２を一体
化したのち、この一体化した１と２を真空中
（10^-2mmＨｇ）、200℃で10分間加熱することによ
り、この１と２をより強固かつ確実に溶着させる
ことができる。同様に、負極端子板６と負極封口材７（外寸法
22×27mm、内寸法16×21mm）を熱溶着する。組立方法としては、負極端子板６を下にして、
順次、リチウム５、セパレータ４、正極合剤シー
ト３を挿入して、積層する。次に、正極端子板１
を載置、被せて一対の正、負極端子板１，６の周
辺端部でヒートシールを行い、電池を完全密封す
る。このヒートシールの際、正極端子板１と負極
端子板６の外形寸法が異なつているので、この周
辺端部でのシヨートが防止されている。このようにして組立てた電池の外形寸法は正極
端子板１の外形寸法27×32mmと同じなので、第３
図に示すように、電池外形仕上げ抜を施して外形
寸法23×28mmとする。第３図は本発明の電池の外形仕上げ抜前後の平
面図と断面図である。図中、電池Ａは外形仕上げ抜前で、外形寸法は
27×32mmであり、電池Ｂは外形仕上げ抜後で、外
形寸法は23×28mmである。第４図は第３図に示した外形仕上げ抜前後の電
池周辺端部の拡大図であり、電池Ａが外形仕上げ
抜前で電池Ｂが外形仕上げ抜後である。この図
中、l₁はカツトする長さであるが概ね２mmあれば
十分である。このl₁の長さを大きくし過ぎればカ
ツトして捨てる材料が多くなり、材料が無駄とな
る。また、電池外形仕上げ抜を施した電池Ｂにおい
ても正極端子板１と負極端子板６の外形寸法がl₂
だけズレているので外形仕上げ抜の際、正極と負
極とがシヨートすることはない。このズレ量l₂は
0.3〜0.5mmが適切である。第５図は電池外形仕上げ抜を実施していない従
来電池の周辺端部図であり、所定寸法により封口
材２と７がハミ出した分だけ大きくなつている。また、ハミ出した封口材がＣ、Ｄ部のように、
正極端子板１と負極端子板６の外周端部表面に付
着し、厚みをアツプしたり、外観を汚くなつた
り、電気的導通が取れなくなつたりする欠点を有
している。最後に、電池外形仕上げ抜を施した電池を20ｍ
Ａで６分間放電し実用に供する訳である。この放電量としては電池理論容量の約５％が適
切である。また、この放電量が適切であるかどうかは室温
下、24〜48Hv後の開路電圧が3.0〜3.1Vであるこ
とから判る。ちなみに、放電処理前の開路電圧は
3.38〜3.44Vである。まず、第１図に示す本発明の電池構造の電池と
正、負極端子板の外形寸法が同一である従来構造
の電池を組立て、組立直後のシヨート電池数を調
べた。シヨート不良は開路電圧が3V以下の電池
とした。その結果を第１表に示す。 [Industrial Field of Application] The present invention relates to a flat plate battery, and more particularly to a flat battery with significantly improved sealing properties and excellent long-term reliability. The present invention also relates to a flat plate battery that prevents shoots inside and on the outer periphery of the battery. moreover,
The present invention relates to a stable flat plate battery that exhibits little flaking even during long-term storage or use. [Summary of the Invention] The present invention provides a flat plate lithium battery in which a power generating element is housed between a positive terminal plate and a negative terminal plate which also serve as an exterior, and the peripheries of the positive and negative terminal plates are sealed with a sealing material. By using a two-type, three-layer laminate film composed of maleic acid-modified polyethylene resin/high-density polyethylene resin/maleic acid-modified polyethylene resin as the sealing material, the sealing performance of the battery is greatly improved. In addition, by heat-welding this sealing material to the positive terminal plate and the negative terminal plate in advance, the power generation elements filled in the battery are not deteriorated by the heat during heat sealing, and are reliably sealed by heat sealing. It is something that can be done. Furthermore, by using a separator made by stacking and rolling two sheets of polypropylene nonwoven fabric, and by sandwiching and fixing the periphery of the separator with the sealing material, it is possible to prevent this shot or the outer periphery of the separator from shooting through the separator. That is. By changing the external dimensions of the positive terminal plate and the negative terminal plate, shorting between the positive and negative electrodes is prevented during heat sealing and finishing cutting of the battery external shape. After heat sealing, the external dimensions of the battery are adjusted to a predetermined value by performing finishing punching to remove the protruding portion of the sealing material. By reacting the positive electrode mixture sheet with the electrolyte in advance,
By using this reaction-treated positive electrode mixture sheet as a positive electrode active material of a battery, it is intended to prevent battery swelling due to gas generation during storage or use of the battery. By using a positive terminal plate or a negative terminal plate that has been previously drawn, it is possible to easily align the battery power generating element within the battery, and to prevent misalignment. After manufacturing the battery, the battery is discharged to about 5% of its theoretical capacity before being stored or used, thereby minimizing the amount of battery swelling during storage or use. After the battery is manufactured, the battery is discharged and the open circuit voltage of the battery is set to 3.0 to 3.1V, thereby minimizing the amount of battery swelling during storage or use. [Prior Art] Conventionally, a flat battery has been used, in which a power generation element is housed between a sealing plate that also serves as a positive electrode current collector plate and a sealing plate that also serves as a negative electrode current collector plate, and the periphery of the sealing plate is sealed with an insulating material. A flat battery using maleic anhydride-modified polyethylene resin as the insulating material has been known. Furthermore, a method has been known in which a polypropylene nonwoven fabric is used as a separator and the peripheral edge of the separator is not fixed. The method of bonding the maleic anhydride-modified polyethylene resin and the sealing plate may be any of the hot plate bonding method, impulse bonding method, and ultrasonic bonding method. It was known that bonding could be achieved by applying a pressure of 3 to 5 cm ² for 3 to 5 seconds. Furthermore, it was known that the size of the positive electrode sealing plate and the negative electrode sealing plate were the same. Such a conventional battery is disclosed in Japanese Unexamined Patent Publication No. 59-83340. [Problems to be solved by the invention] Conventional batteries use a single layer of maleic anhydride-modified polyethylene resin as a sealing material, so when heat sealing the battery periphery with heat and pressure,
The problem was that the sealing material protruded too far outside the periphery of the battery, causing it to shoot between the positive and negative terminal plates. The reason for this shooting is that the sealing material is heated to or above its melting point while being pressurized.
This is because the fluidity of the sealant increases and leaks out to the periphery of the battery, reducing the amount of sealant interposed between the positive terminal plate and the negative terminal plate. Furthermore, if the pressure during heat sealing is uneven, or if there are protrusions such as punching burrs on the outer periphery of the positive and negative terminal plates, the positive and negative electrodes will come into contact with each other, resulting in a shorted state.
Further, the areas where the amount of the sealing material is large and the areas where the amount is small form areas where the positive and negative electrode terminal plates and the sealing material are in good contact with each other and areas where the sealing material is in poor contact with each other. This poor adhesion caused poor sealing, allowing air and moisture to enter the battery from outside the battery, resulting in the deterioration of the negative electrode lithium. Further, when a single resin having heat-sealing properties is used as described above, there is a drawback that it is difficult to finish the heat-sealed portion around the battery periphery to a constant thickness. SUMMARY OF THE INVENTION The object of the present invention is to solve these conventional drawbacks and thereby provide a flat plate lithium battery that is thin, has significantly improved sealing properties, and has excellent long-term reliability. Since the peripheral edge of the separator and the sealing material are not fixed, the separator, the positive electrode mixture, and the negative electrode lithium sheet may be misaligned, resulting in shots caused by contact between the positive electrode mixture and lithium, and damage between the positive electrode mixture and the negative electrode sealing plate. There was a drawback that shoots were generated either due to contact or shoots due to contact between lithium and the positive electrode sealing plate. Since the external dimensions of the positive electrode sealing plate and the negative electrode sealing plate are the same, there are disadvantages in that they may be shot during heat sealing, or the resin used for the sealing material may protrude, resulting in the external dimensions becoming larger than the predetermined dimensions. SUMMARY OF THE INVENTION It is an object of the present invention to solve these conventional drawbacks and thereby prevent shoots during heat sealing during battery assembly and during battery use or storage. [Means for Solving the Problems] In order to solve the above problems, the present invention stores a power generation element between a positive terminal plate and a negative terminal plate that also serve as exteriors, and A flat plate lithium battery sealed with a sealing material, by using a two-type, three-layer laminate film composed of maleic acid-modified polyethylene resin/high-density polyethylene resin/maleic acid-modified polyethylene resin as the sealing material, further By stacking one sheet of this sealing material on the positive terminal plate side and one sheet on the negative terminal plate side, we have greatly improved the sealing properties of the battery and blocked air and moisture from entering from the outside. , a flat-plate lithium battery with excellent long-term reliability was realized. In addition, it was possible to prevent shoots during heat sealing and to make the thickness of the heat seal portion uniform, thereby providing a more reliable battery. [Function] The present inventor has conducted intensive research on the structure and resin of the sealing material. Maleic acid-modified polyethylene resin is obtained by graft polymerizing maleic acid to medium density polyethylene. The grafting rate of this maleic acid is 0.05
~0.2% is optimal. When the grafting rate exceeds 0.2%, water permeability increases, making it unsuitable as a sealing material for lithium batteries. On the other hand, 0.05%
If it is less than that, the adhesion to the positive and negative electrode terminal plates made of metal will be poor and it will no longer function as a sealing material. This maleic acid modified polyethylene film has a thickness of 30±5μ, mp120℃, melt index
0.3, density 0.91. Furthermore, if the thickness of this film is too thin, the resin may flow and flow out of the battery sealing portion during heat sealing, increasing the occurrence of sealing defects. 20μ in the experiment
is the minimum required thickness. On the other hand, if the thickness of this film is too thick, the resin will seal sufficiently even after subtracting the outflow of resin due to heat and pressure during heat sealing, but it is not a good measure against moisture intrusion from outside the battery. The reason for this is that polyethylene grafted with maleic acid has improved adhesion to metals, but moisture permeability is increased compared to polyethylene not grafted with maleic acid. In short, it is important to make the thickness of the heat-sealed part uniform and to keep it to the minimum necessary thickness in order to ensure sealing performance. Next, high density polyethylene film will be explained. This high-density polyethylene film is not grafted with maleic acid, so it does not adhere to metal, and it plays the role of a spacer to keep the distance between the positive and negative terminals, that is, the thickness of the battery seal part, constant. There is. The thickness of this film can be arbitrarily set depending on the thickness of the battery. In the embodiment of the present invention, the thickness of the battery is 0.5mm, so the thickness of the film is 50~
200μ is appropriate. The film has an mp of 129°C, a melt index of 0.6, and a density of 0.95. The melt index is an index indicating the fluidity of the resin, and the larger the number, the poorer the fluidity. In other words, since this high-density polyethylene is the same polyethylene as maleic acid-modified polyethylene, it melts under heat, so there is no problem with moisture intrusion from this joint surface, and the mp is 9°C higher than that of maleic acid-modified polyethylene, and it has less fluidity. Because there are few
It can be a good spacer. Furthermore, since maleic acid is not grafted, it has low moisture permeability and can be used as a good sealing material. Next, the reason why the present invention uses a two-type, three-layer laminate film, that is, maleic acid-modified polyethylene/high-density polyethylene/maleic acid-modified polyethylene, as a sealing material will be explained. One of the reasons for this is that there is no front or back side of the film.
There is no need to distinguish between the adhesive layer surface (maleic acid-modified polyethylene surface) and the non-adhesive layer surface (high-density polyethylene surface). One reason for this is that if this sealing material is welded to the positive and negative terminal plates in advance, when heat sealing is performed after filling the battery power generation elements, the mp is lower than when bonding high-density polyethylene pieces together, and the adhesive properties are lower. A method of adhering maleic acid-rich polyethylene to each other allows for easy and reliable sealing. Furthermore, the heat sealing temperature is low and sealing can be performed in a short time, reducing damage and deterioration caused by heat to the lithium in the lithium battery, the organic electrolyte, the separator, and the positive electrode active material. It is optimal to manufacture the two-type, three-layer laminate film, which is the sealing material of the present invention, by the inflation method, and using the two-type, three-layer laminate film using this method improves the sealing performance at the sealing part of the battery. Let me explain the reason. Generally, the film manufacturing methods are (1) T-die method and
(2) There is an inflation method. The T-die method is widely used because it can produce films at a low cost, but when heat is applied for uniaxial stretching, the coefficient of thermal contraction and thermal expansion differs in the length and width directions, so this film is used as a sealing material. It has the disadvantage that the seal width varies depending on the direction. Naturally, the narrower the seal width, the worse the sealing performance. On the other hand, the inflation method is an expensive method for producing films, but because it is biaxially stretched, the thermal contraction rate and thermal expansion rate are isotropic even when heated and cooled. Therefore, the seal width can be made the same anywhere on the film. This makes it possible to uniformly control the width of the sealing material and the seal width. The reason why the sealing material of the present invention is heat-welded to the positive and negative terminal plates in advance will be explained. The present inventor also first placed a sealing material frame on top of the positive electrode terminal plate, placed the positive electrode active material and separator in the frame in order, and then overlapped and covered the negative electrode terminal plate with lithium arranged inside. I tried to heat seal the outer periphery of the battery, but the seal was not possible. This is because the positive and negative terminal plates are made of metal such as nickel or stainless steel, so heat dissipates during heat sealing. Furthermore, since the battery contains contents, more heat is transferred and absorbed during heat sealing. If you still want to heat seal, you can increase the heat sealing temperature or increase the pressure time, but this may cause the battery contents to be heated more than necessary, or the thermal expansion coefficient of the terminal board and sealing material Since the shrinkage rates are different, wrinkles may occur in the heat-sealed portion on the outer periphery of the battery, or the entire battery may warp, which is inconvenient. In the present invention, the sealing material according to the present invention is heat-welded to the positive and negative terminal plates in advance. In this way, there is no need to dissolve lithium at mp170°C or thermally decompose the organic electrolyte. That is, sufficient heat, pressure, and time can be applied as necessary for welding, so that the adhesiveness between the positive and negative terminal plates and the sealing material is perfect. In the case of the present invention as well, after the contents of the battery are filled, the outer periphery of the battery is sealed by heat sealing, and since the sealants made of the same material are bonded to each other, sealing can be easily achieved. Furthermore, welding of the positive and negative terminal plates and the sealing material cannot be directly performed in one step. In the present invention, first, the positive and negative electrode terminal plates and the positive and negative electrode sealing materials are aligned and overlapped and temporarily welded by hot pressing at 160° C. and a pressure of 2 kg/cm ² for 3 seconds. At this point, the sealing material is only weakly bonded to the positive and negative terminal plates. After this, the sealing material is temporarily welded and the positive and negative terminal plates are
Completely sealed with sealant, heat treated at 200℃ for 10 minutes.
The negative terminal plate will be welded. In the present invention, as a separator, two sheets of polypropylene nonwoven fabric having a basis weight of 20 g/m ² are stacked and rolled. The thickness of the polypropylene nonwoven fabric before rolling was 60 μm, and two sheets were stacked and rolled to have a total thickness of 80 μm. The weight of this two-layered rolled separator is 40 g/m ² . Also,
The nonwoven fabric before rolling is manufactured by a micro spunbond spinning method and is impregnated with an anionic surfactant. If this surfactant is not impregnated, the polypropylene nonwoven fabric has poor wettability with an organic electrolytic solution made of propylene carbonate or the like, resulting in a disadvantage that the internal resistance of the battery increases. The reason why the present invention uses a specially processed separator is to prevent the lithium of the negative electrode active material and the positive electrode active material from penetrating the separator and being shot when the top and bottom of the battery are strongly pressed. . Figure 6 shows the top and bottom of the battery using various separators.
The battery was heated to 80℃ while applying an external pressure of 10Kg/ ^cm2 .
This is a graph showing open circuit voltage measured when stored at a humidity of 90 to 95% RH. In the figure, ○ is the separator according to the present invention, □ is a polypropylene nonwoven fabric with a thickness of 120μ and a basis weight of 37g/ ^m2 , △ is a polypropylene nonwoven fabric with a thickness of 50μ and a basis weight of 20
g/m ² single-layer polypropylene non-woven fabric. Since the thickness of the battery of the present invention is 0.5 mm, it is necessary to make the thickness of the separator as thin as possible in order to increase the battery capacity. If the single layer separator is 50μ thick, it will be shot through the separator. On the other hand, if the separator has a thickness of 120 μm, it will not pass through the separator, but it is too thick and is therefore unsuitable for the battery of the present invention. The reason why the separator according to the present invention is effective in preventing shoots is because two sheets of nonwoven fabric with a large basis weight are stacked and rolled, so there are no through holes (pinpoles) in the separator and a detour path is formed. It is. Furthermore, since the holes are misaligned by stacking two separators, there are no straight through holes. In addition, the thickness was increased to make the separator even thinner.
25μ microporous polypropylene film or thickness 10~
Although 50μ capacitor paper was used, the internal resistance of the battery is as high as several kΩ, so it cannot be used in the battery of the present invention. The reason why this internal resistance becomes large is that in the battery of the present invention, only a very small amount of electrolyte can be filled into the battery, so that the separator is not sufficiently wetted. As shown in FIG. 1, the battery of the present invention has a separator periphery sandwiched between positive and negative electrode sealants. Since the material of the separator is polypropylene and the material of the sealing material is polyethylene, the two are thermally welded and fixed during heat sealing. By fixing the periphery of the separator with the sealing material in this way, batteries can be stored for long periods of time,
Even if the positive electrode active material spills during use, lithium deterioration due to migration to the negative electrode active material lithium side can be prevented. Further, even if the positive electrode active material and the negative electrode active material are misaligned, contact between the positive electrode active material and the negative electrode active material can be prevented. The present invention is particularly effective when the battery of the present invention is bent. The reason why the present invention heat-seals the outer periphery of the battery and, after assembling the battery, performs cutting to finish the battery to a predetermined size will be explained. FIG. 5 is a sectional view of the peripheral portion of a battery that has not been subjected to conventional external finishing punching. In the figure, 1 is a positive electrode terminal plate cut in advance to predetermined dimensions, 2 is a positive electrode sealing material, 6 is a negative electrode terminal plate cut in advance to predetermined dimensions, and 7 is a negative electrode sealing material. As shown in this figure, when sealing the outer periphery of the battery with a heat seal, there is a drawback that the sealing material inevitably flows out of the battery of a predetermined size and sticks out. In other words, the finished battery may differ from the predetermined battery shape or be larger in size due to the protrusion. Therefore, the present invention is to make either the positive terminal plate or the negative terminal plate sufficiently large in size, heat seal it, and after assembling the battery, finish punching the outside of the battery to a predetermined size. FIG. 3 and FIG. 4 are diagrams showing an embodiment of the present invention. 3 and 4 illustrate an example in which the positive terminal plate is set larger than the negative terminal plate. FIG. 3 is a plan view and a cross-sectional view of a battery to which the present invention is applied before and after the external shape is finished. In the figure, battery A is in the shape immediately after battery assembly, and the external shape has not yet been punched. Battery B has the outer shape of battery A finished to a predetermined size. FIG. 4 is an enlarged view of the outer periphery of batteries A and B in FIG. 3. In the figure, 1 is a positive electrode terminal plate, 2 is a positive electrode sealing material, 6 is a negative electrode terminal plate, and 7 is a negative electrode sealing material. If battery A is cut along cut line C, battery B of a predetermined size will be obtained. Further, the size of the positive electrode terminal plate 1 of the battery A may be set larger than the protruding portions of the positive electrode encapsulant 2 and the negative electrode encapsulant 7. If the size of the positive electrode terminal plate 1 is made larger than the protruding portions of the sealing materials 2 and 7 in this manner, positioning can be performed based on the outer shape of the positive electrode terminal plate 1, and the outer shape can be finished and cut to a predetermined size. Further, it is appropriate that the dimensional difference l ₁ between the positive electrode terminal plates 1 of batteries A and B is 2 mm or more. However, this dimensional difference
If _l1 is too large, the material cost for the positive terminal plate 1 of battery A, which must be discarded, will be wasted. The reason why the external dimensions of the positive terminal plate 1 and the negative terminal plate 6 are different in the present invention will be explained. One of the reasons for this is to prevent the positive terminal plate 1 and the negative terminal plate 6 from coming apart during heat sealing to seal the battery. The mechanism of this shot generation is that the highest pressure is applied to the outermost edge of the battery during heat sealing, and press burrs are generated on the positive terminal plate 1 and the negative terminal plate 6. The second reason is that when punching out the battery external shape, if the positive terminal plate 1 and negative terminal plate 6 are punched out at the same time, the positive terminal plate 1 and negative terminal plate 6 will come into contact with each other due to punching burrs, resulting in shorts. It is. By changing the dimensions of the positive terminal plate 1 and the negative terminal plate 6 in this manner, it is possible to prevent shorts during heat sealing and during external finishing punching. The reason why the present invention allows the positive electrode active material to react with the electrolytic solution in advance will be explained. It has been known that ethylene carbonate and MnO ₂ react to generate CO ₂ gas. For example, Blomgren, G. E. (1983), “Lithium
Batteries” (JPGabano, ed.), P22,
Academic Press, New York and London.
The following reaction formula is described. The present invention uses 1 mol of the positive electrode mixture sheet according to the present invention.
By optimizing the reaction conditions with an electrolyte made of propylene carbonate (PC) containing Liclo ₄ , gas generation due to the reaction between MnO ₂ and the electrolyte is prevented. FIG. 8 is a diagram showing the amount of cell swelling at different reaction temperatures and reaction times between the positive electrode mixture sheet and the electrolyte. In the battery used in Figure 8, the positive electrode mixture sheet was heated at 80°C.
After processing in the electrolytic solution for 3 hours and 15 hours at 100° C. and 120° C., respectively, the positive electrode mixture sheet was taken out from the electrolytic solution and sealed in a battery together with the separator 4 and the electrolytic solution. In the figure, A is the case of 15 hours treatment, B
is the case of 3 hour treatment. After storing this battery in a constant temperature and humidity chamber at 80° C. and 90% relative humidity (RH) for 5 days, the difference in battery thickness before and after storage was determined, and this was taken as the amount of battery swelling. The unit of this battery swelling amount is 1=0.01mm. From this Figure 8, it is desirable that the temperature is 100°C or higher.
Also, 15 hours is better than 3 hours. Practically speaking, conditions of 100°C, 15 hours, and 120°C, 15 hours are suitable. Thus, it is presumed that the effect of reacting the positive electrode mixture sheet and the electrolytic solution in advance is that the active portion of MnO ₂ is deactivated by the reaction of MnO ₂ in the positive electrode mixture sheet with the electrolytic solution. If the reaction conditions of the present invention are used, the electric capacity of MnO ₂ will not be reduced, and therefore the battery capacity will not be reduced. Reactions at temperatures above 140°C have the disadvantage of decreasing battery capacity. The reason why the present invention performs discharge treatment after assembling the battery of the present invention will be explained. Table 7 shows the open circuit voltage (Voc), internal resistance (Ri), and amount of battery swelling when the batteries of the present invention were treated with various discharge currents and discharge times. The amount of battery flaking was determined by discharging the battery under various conditions, storing it at 80°C and 90% RH, and examining the difference in battery thickness before and after storage on 5-day sheets. As is clear from Table 7, the discharge current is 20
mA is most effective in suppressing the amount of battery swelling, and a discharge time of 6 minutes is more effective in reducing the amount of battery swelling than 2 minutes. In this way, if the discharge current is increased and the discharge time is increased, the amount of swelling in the battery will be reduced. The inventor estimates that 5 days of storage at 80°C and 90% RH is equivalent to 1 year of storage at 25°C.
In order to keep the amount of battery swelling within 5 after storage for 15 days, or 3 years at 25°C, conditions of 20 mmA x 6 minutes or more are appropriate. When the battery is discharged at this 20 mA for 6 minutes, the discharge amount is 2 mAh, which is an example of the lithium flat plate battery according to the present invention, CS2328 (open circuit voltage 3 V, nominal capacity 30 mAh, 23 x 28 x 0.5 mm). This corresponds to 5.2% of the theoretical battery capacity. It is estimated that increasing this discharge amount will stabilize the MnO ₂ in the positive electrode mixture sheet and reduce the generation of CO ₂ due to reaction with the electrolyte, but if it is discharged too much, the battery capacity will also decrease. It has some drawbacks. Therefore, it is necessary to appropriately balance the amount of discharge processing and the amount of battery swelling. As detailed above, by using a two-type, three-layer laminate film made of maleic acid-modified polyethylene and high-density polyethylene resin as the sealing material, and by heat-welding this sealing material to the positive terminal plate and the negative terminal plate in advance. , it was possible to perform heat sealing easily and reliably, and to significantly improve sealing performance. A separator made by stacking and rolling two sheets of polypropylene nonwoven fabric with a basis weight of 20 g/m ² is used, and the outer periphery of this separator is sandwiched between the sealing material,
By fixing it, it was possible to prevent shoots inside the battery. By using a drawn positive terminal plate or negative terminal plate with a radius of 3 mm or more at the corner of the drawing shape, sealing performance is greatly improved, and lithium, separators, and positive electrode mixture sheets are By providing a positioning guide when placing power generation elements such as , we were able to prevent misalignment. By changing the external dimensions of the positive and negative terminal plates, it is possible to prevent shortening during heat sealing and shortening when removing the finished external shape of the battery. By performing finishing punching on the battery external shape, the external dimensions of the battery could be reduced to predetermined dimensions without impairing its beauty. By treating the positive electrode mixture sheet with an electrolytic solution and then incorporating the positive electrode mixture sheet into a battery, it was possible to reduce the swelling of the battery during storage or use. After battery manufacturing, by discharging the battery,
It was possible to reduce the swelling of the battery during storage or use. [Example] Examples of the present invention will be described below based on the drawings. Example 1 FIG. 1 shows an example of a flat plate lithium battery to which the present invention is applied. First, size 23 x 28 x 0.5 mm (CS2328,
Voc3V, nominal capacity 30mAh) will be explained. In the figure, 1 is the positive terminal plate, made of SUS430,
It is made of SHOMAC30-2 and has a thickness of 30μ.
As shown in FIGS. 1, 2, and 3, this positive terminal plate is drawn in advance. As shown in Figure 3, the R part is 3 mm or more, and the drawing depth d is 0.16 ~
It is 0.22mm. Furthermore, the external dimensions of the positive terminal plate are 27 x 32 mm. A positive electrode mixture sheet 3 mainly composed of manganese dioxide is inserted and placed inside the positive electrode terminal plate 1 . Next, a separator 4 is placed on the positive electrode mixture 3. In addition, this positive electrode mixture sheet 3 is treated with an electrolytic solution in advance before being incorporated into a battery. In this treatment method, n = 100 positive electrode mixture sheets 3 are prepared,
1 mol LiclO ₄ /propylene carbonate (PC)
After immersing it in 50c.c. of electrolyte solution and sealing it tightly,
Heat at 120℃ for 15 hours. After this heating, take out this positive electrode mixture sheet and immerse it in 50 c.c. of new electrolyte at room temperature for 30 minutes or more to replace the old electrolyte contained in the positive electrode mixture sheet with the new electrolyte. . The positive electrode mixture sheet treated with this new electrolyte is taken out and used as the positive electrode active material of the battery. The relationship between this electrolyte and the theoretical capacity of MnO ₂ to be treated is as follows: theoretical capacity of MnO ₂ to be treated/necessary amount of electrolyte = 30 to 100 mAh/cc. This separator 4 is made by rolling and rolling two sheets of polypropylene nonwoven fabric with a basis weight of 20 g/m ² one on top of the other. Further, the outer peripheral portion of the separator 4 is sandwiched and fixed between the sealing materials 2 and 7. Further, when heat sealing the outer circumferential portion of the battery, the outer circumferential portion of the separator 4 is also welded to the sealing materials 2 and 7, and the separator 4 is fixed more securely. 5 is lithium, which is a negative electrode active material, and is pressure-bonded to the inside of the negative electrode terminal plate 6. This negative electrode terminal plate 6 is made of nickel, aluminum, stainless steel, etc., and has external dimensions of 22×27 mm and a thickness of 30 μm. FIG. 2 is a detailed sectional view of the sealing material according to the present invention.
In the figure, 2a and 7a are maleic acid-modified polyethylene,
2b and 7b are high density polyethylene. 2 is a positive electrode sealing material welded in advance to the outer circumferential inner surface of the positive electrode terminal plate 1, which is a film manufactured by an inflation method using a two-layer, three-layer laminate of maleic acid-modified polyethylene/high-density polyethylene/maleic acid-modified polyethylene. be. Reference numeral 7 denotes a negative electrode sealing material welded in advance to the outer peripheral inner surface of the negative electrode terminal plate 6, which is a film manufactured by an inflation method using a two-layer, three-layer laminate of maleic acid-modified polyethylene/high-density polyethylene/maleic acid-modified polyethylene. be. The thickness of the sealing materials 2 and 7 is 30±5μ for the maleic acid-modified polyethylene 2a and 7a, and 60±5μ for the high-density polyethylene 2b and 7b. Further, the sealing materials 2 and 7 are welded to the outer circumferential inner surfaces of the positive terminal plate 1 and the negative terminal plate 6, respectively, in the following manner. Positive electrode terminal plate 1 and positive electrode sealing material 2 (outside dimensions 23 x 28
(inner dimensions: 16 mm, 6 x 21 mm, 6 mm) are aligned and overlapped so that the positions do not shift, and the hot plate is crimped from the positive terminal plate 1. At this time, the temperature was 160±10° C., the pressure was 2±0.5 Kg/cm ² , and the pressurization time was 3 to 5 seconds. After integrating the positive electrode terminal plate 1 and the positive electrode sealing plate 2 in this way, these integrated parts 1 and 2 are heated at 200°C for 10 minutes in a vacuum (10 ^-2 mmHg) to separate them. It is possible to weld more firmly and reliably. Similarly, the negative electrode terminal plate 6 and the negative electrode sealing material 7 (outer dimensions
22 x 27 mm, inner dimensions 16 x 21 mm) are heat welded. The assembly method is as follows: with the negative terminal plate 6 facing down,
Lithium 5, separator 4, and positive electrode mixture sheet 3 are sequentially inserted and laminated. Next, positive terminal plate 1
is placed and covered, and the peripheral edges of the pair of positive and negative terminal plates 1 and 6 are heat-sealed to completely seal the battery. During this heat sealing, since the external dimensions of the positive terminal plate 1 and the negative terminal plate 6 are different, shortening at the peripheral end portions is prevented. The external dimensions of the battery assembled in this way are the same as the external dimensions of positive terminal plate 1, 27 x 32 mm, so the third
As shown in the figure, the external dimensions of the battery are 23 x 28 mm by finishing punching. FIG. 3 is a plan view and a cross-sectional view of the battery of the present invention before and after finishing the external shape. In the figure, battery A is before external finishing and external dimensions are
The outer dimensions of battery B are 23 x 28 mm after the outer dimensions have been removed. FIG. 4 is an enlarged view of the peripheral end of the battery shown in FIG. 3 before and after the outer shape is finished, with battery A being before the outer shape finishing being punched and battery B being after the outer shape finishing is being punched. In this figure, _l1 is the length to be cut, and approximately 2 mm is sufficient. If the length of _l1 is made too large, more material will be cut and thrown away, resulting in wasted material. In addition, even in battery B which has been subjected to battery external finish cutting, the external dimensions of the positive terminal plate 1 and negative terminal plate 6 are l ₂
Since the positive and negative electrodes are misaligned, the positive and negative electrodes will not be shot when finishing the external shape. This amount of deviation l ₂ is
0.3-0.5mm is suitable. FIG. 5 is a peripheral end view of a conventional battery which has not been subjected to finishing punching, and is enlarged by the extent that the sealing materials 2 and 7 protrude due to predetermined dimensions. Also, the protruding sealing material is shown in parts C and D,
It adheres to the outer peripheral end surfaces of the positive terminal plate 1 and the negative terminal plate 6, resulting in increased thickness, poor appearance, and failure to maintain electrical continuity. Finally, 20 m
The battery will be discharged for 6 minutes at A for practical use. Approximately 5% of the battery's theoretical capacity is appropriate for this discharge amount. Moreover, whether this amount of discharge is appropriate can be determined from the fact that the open circuit voltage after 24 to 48 Hv at room temperature is 3.0 to 3.1 V. By the way, the open circuit voltage before discharge treatment is
It is 3.38~3.44V. First, a battery having a conventional structure having positive and negative terminal plates having the same external dimensions as a battery having the battery structure of the present invention shown in FIG. 1 was assembled, and the number of short batteries immediately after assembly was examined. Short-circuit failure was caused by batteries with an open circuit voltage of 3V or less. The results are shown in Table 1.

【表】表より明らかなように、従来電池はシヨート不
良が極めて多い。以降、本発明の効果を調べることは、すべて第
１図に示すような正極端子板と負極端子板の外形
寸法が異なる電池で行つた。次に、本発明に係る絞り加工した正極端子板を
用いた本発明電池と正、負極端子板のいずれもが
平板である従来電池について性能を比較した。試験方法は電池を60℃、RH90〜95％の恒温恒
湿層に貯蔵し、開路電圧（V_pc）、内部抵抗
（Ri）、厚み(H)の変化を調べた。この結果を第２
表に示す。データはｎ＝24である。表中、ｘはデータｎ＝24の平均値、Ｒはデータ
の最大値と最小値の差を示す。また、V_pc、Ri、
Ｈの単位は各々、Ｖ、Ω、mmである。[Table] As is clear from the table, shoot defects are extremely common in conventional batteries. Hereinafter, the effects of the present invention were all investigated using batteries in which the positive terminal plate and the negative terminal plate had different external dimensions as shown in FIG. Next, performance was compared between a battery of the present invention using the drawn positive terminal plate according to the present invention and a conventional battery in which both the positive and negative terminal plates were flat plates. The test method was to store the battery in a constant temperature and humidity layer at 60°C and RH 90-95%, and examine changes in open circuit voltage (V _pc ), internal resistance (Ri), and thickness (H). This result is the second
Shown in the table. The data are n=24. In the table, x represents the average value of data n=24, and R represents the difference between the maximum and minimum values of the data. Also, V _pc , Ri,
The units of H are V, Ω, and mm, respectively.

【表】【table】

【表】第２表から明らかなように、本発明電池は従来
電池に比べて、開路電圧の維持性が良好であり、
内部抵抗の上昇も少なく優れていることが分か
る。また、本発明電池は電池厚みの増加も少なく優
れていることが分かる。本発明電池が優れていることの理由は本発明電
池の正極端子板が予め絞り加工されているため、
電池発電要素を内蔵しても電池外周部のヒートシ
ール時にこのシール部に無理な力が加わわらない
からである。このような予め正極端子板を絞り加工しておく
ことにより、良好なシール状態を長期間に渡つて
維持できるのである。次に、第２図に示した本発明に係る二種三層フ
イルムを封口材として用いた本発明電池と一種一
層フイルムを封口材として用いた従来電池につい
て電池封口時のシヨート不良率を比較した。この
結果を第３表に示す。データはｎ＝100の不良率
（％）である。[Table] As is clear from Table 2, the battery of the present invention maintains the open circuit voltage better than the conventional battery.
It can be seen that the increase in internal resistance is also small and is excellent. Furthermore, it can be seen that the battery of the present invention is excellent with less increase in battery thickness. The reason why the battery of the present invention is superior is that the positive terminal plate of the battery of the present invention is drawn in advance.
This is because even if the battery power generating element is built-in, no undue force is applied to the sealing portion during heat sealing of the outer periphery of the battery. By drawing the positive electrode terminal plate in advance, a good sealing state can be maintained for a long period of time. Next, we compared the shot defect rate during battery sealing between a battery of the present invention using the 2-type 3-layer film according to the present invention as a sealing material and a conventional battery using a 1-type 1-layer film as a sealing material, as shown in Fig. 2. . The results are shown in Table 3. The data is the defective rate (%) of n=100.

【表】第３表より明らかなように、本発明電池は従来
電池に比べてシヨート不良率が極めて少なく優れ
てることが分かる。この理由は、本発明電池が封
口材が二種三層フイルムの構成となつていること
によるものである。すなわち、マレイン酸変性ポ
リエチレンに比べて融点が約10℃高い高密度ポリ
エチレンをサンドイツチにして用いているので、
ヒートシール時にマレイン酸変性ポリエチレンが
融点に達して溶着性を示し、軟らかくなつても高
密度ポリエチレンな軟らかくならず正、負極端子
板間の絶縁部材として機能できる。さらに、本発明に係る封口材と従来の封口材に
ついて、水分の透湿性について調べた。試験方法は次のようである。まず、本発明に係
る封口材と従来の封口材を用いて、第１図に示す
ような容器を作り、発電要素の代わりに、電解液
200μのみをこの容器内に充填してヒートシー
ルした。この電解液のみを内蔵した容器を温度80
℃、RH90〜95％の恒温恒湿槽内に10日間貯蔵
し、容器内により電解液100μをマイクロシリ
ンジにて採集しカールフイツシヤー水分計により
水分量を測定した。その水分量の結果を第４表に
示す。表中、データはｎ＝24である。表中、は
データｎ＝24の平均値、Ｒはデータの最大値の最
小値の差を示す。単位はppmである。なお、実験に使用した電解液は１モルLiclO₄を
溶かしたプロピレンカーボネートであり、この含
有水分量は15ppmである。[Table] As is clear from Table 3, it can be seen that the battery of the present invention is superior to the conventional battery with extremely low shot defect rate. This is because the battery of the present invention has a structure in which the sealing material is a two-type, three-layer film. In other words, we use high-density polyethylene, which has a melting point about 10°C higher than that of maleic acid-modified polyethylene, as a sandwich sandwich.
During heat sealing, the maleic acid-modified polyethylene reaches its melting point and exhibits welding properties, and even when it becomes soft, it does not become soft like high-density polyethylene and can function as an insulating member between the positive and negative terminal plates. Furthermore, the moisture permeability of the sealing material according to the present invention and the conventional sealing material was investigated. The test method is as follows. First, a container as shown in FIG. 1 is made using the sealing material according to the present invention and a conventional sealing material, and an electrolytic solution is used instead of the power generation element.
Only 200μ was filled into this container and heat sealed. The container containing only this electrolyte is heated to 80°C.
It was stored in a constant temperature and humidity chamber at 90-95% RH for 10 days, and 100μ of the electrolyte was collected from the container using a microsyringe, and the water content was measured using a Karl Fischer moisture meter. The results of the moisture content are shown in Table 4. In the table, the data is n=24. In the table, R indicates the average value of data n=24, and R indicates the difference between the maximum value and the minimum value of the data. The unit is ppm. The electrolytic solution used in the experiment was propylene carbonate in which 1 mol of LiclO ₄ was dissolved, and the water content was 15 ppm.

【表】第４表より明らかなように、本発明の封口材は
従来の封口材に比べて水分量が少なく、シール性
が優れていることが分かる。この理由は、本発明
の封口材が高密度ポリエチレンに比べれば水分透
過性の大きいマレイン酸変性ポリエチレンを必要
最小限の使用に限定したのに対して、従来の封口
材はマレイン酸変性ポリエチレンのみを使用して
いるためである。次に、封口材を予め正、負極端子板に溶着した
場合と溶着しない場合について、電池封口時のシ
ール不良率を比較して調べた。その結果を第５表
に示す。データはｎ＝100のシール不良率（％）
を示す。[Table] As is clear from Table 4, it can be seen that the sealing material of the present invention has a lower moisture content and excellent sealing performance than the conventional sealing material. The reason for this is that the sealing material of the present invention limits the use of maleic acid-modified polyethylene, which has higher moisture permeability than high-density polyethylene, to the necessary minimum, whereas the conventional sealing material uses only maleic acid-modified polyethylene. This is because it is used. Next, the seal failure rate when sealing the battery was compared and investigated for cases in which the sealing material was welded to the positive and negative terminal plates in advance and cases in which it was not welded. The results are shown in Table 5. Data is seal failure rate (%) of n=100
shows.

【表】第５表より明らかなように、本発明電池は従来
電池と比べて、極めてシール不良が少ない。この
理由は、従来電池はヒートシールの際、電池内に
内蔵されているリチウム、電解液、正極合剤活物
質及び正、負極端子板に熱が吸収されてしまい、
封口材と正、負極端子板の間が溶着しないためで
ある。ヒートシール時の温度を高くすれば、封口
材と正、負極端子板との間が熱溶着するが、しか
し電池に過剰の熱が加わり、電池が膨らんでしま
う欠点がある。一方、本発明は電池の発電要素を
内蔵する前に、封口材と正、負極端子板それぞれ
を十分な熱と圧力で確実に熱溶着しておく。この
ようにしておけば、電池封口時のヒートシールに
おいて、封口材同志のみの熱溶着であるから、発
電要素を熱で傷めることがなく、電池が膨らむこ
とはない。次に、セパレータの材質について、本発明電池
と従来電池の性能を比較した。本発明電池はＡ（○）は目付量20ｇ／m²のポリ
プロピレン不織布を２枚重ねて圧延し、目付量40
ｇ／m²、厚み80μとしたセパレータを使用してい
る。一方、従来電池Ｂ（△）は厚み50μ、目付量
20ｇ／m²ポリプロピレン不織布。従来電池Ｃ（□）は厚み120μ、目付量37ｇ／m²
のポリプロピレン不織布を使用している。試験方法は第７図に示すように、電池７５を２
枚の金属板７２とプラスチツク板７４で挟み、ボ
ルト７１とナツト７３とで締め付ける。電池上下
からの締め付け圧力は10Kg／m²であり、この締め
付けたまま、80℃、RH90〜95％の恒温恒湿槽に
貯蔵し、開路電圧、内部抵抗を調べた。第６図は本発明電池Ａ、従来電池Ｂ、Ｃの開路
電圧と保存期間の関係を示す図である。データは
ｎ＝12の平均値を示す。図から明らかなように、本発明電池Ａと従来電
池Ｃは開路電圧を維持し、良好な結果を得てい
る。一方、従来電池Ｂは、開路電圧が低下してい
る。この理由は、電池上下から圧力を加えられて
も、セパレータを介してリチウムと正極合剤活物
質同志の接触によるシヨートが防止できているた
めと思われる。しかし、従来電池Ｃのセパレータ
は厚みが120μと厚いため、電池を薄くしたいと
いう要求には満足しない。本発明電池はセパレー
タ厚みが80μと薄いにもかかわらず良好な理由
は、２枚の不織布を圧延しながら貼り合わせてい
るためセパレータの開孔がねじれ曲がり、容易に
リチウムと正極合剤活物質が接触しないためであ
る。次に、第１図に示すように、セパレータ周辺部
を封口材に２挟持した本発明電池と挟持しない従
来電池について、組立時のシヨート不良率と電池
を屈曲させたときのシヨート不良率を比較して調
べた。組立時のシヨート不良率はｎ＝100の不良
率を示す。電池屈曲時のシヨート不良率はｎ＝12
を不良率である。電池の屈曲テストはR150mmに
上下方向2000回屈曲させてシヨート不良率を調べ
た。シヨートは開路電圧が3.0V以下とした。[Table] As is clear from Table 5, the battery of the present invention has significantly fewer sealing defects than the conventional battery. The reason for this is that when conventional batteries are heat-sealed, heat is absorbed by the lithium, electrolyte, positive electrode mixture active material, and positive and negative terminal plates built into the battery.
This is because there is no welding between the sealing material and the positive and negative terminal plates. If the temperature during heat sealing is increased, the sealing material and the positive and negative terminal plates will be thermally welded together, but this has the disadvantage that excessive heat is applied to the battery, causing the battery to swell. On the other hand, in the present invention, before incorporating the power generation element of the battery, the sealing material and the positive and negative terminal plates are reliably thermally welded with sufficient heat and pressure. By doing so, during heat sealing when sealing the battery, only the sealing materials are thermally welded together, so the power generating element is not damaged by heat and the battery does not swell. Next, regarding the material of the separator, the performance of the battery of the present invention and the conventional battery were compared. In the battery of the present invention, A (○) is made by stacking and rolling two sheets of polypropylene nonwoven fabric with a basis weight of 20 g/ ^m2.
A separator with a weight of ⁸⁰ μm and a thickness of 80 μm is used. On the other hand, conventional battery B (△) has a thickness of 50μ and a basis weight.
20g/ ^m2 polypropylene non-woven fabric. Conventional battery C (□) has a thickness of 120μ and a basis weight of 37g/m ²
Made of polypropylene non-woven fabric. The test method is as shown in FIG.
It is sandwiched between two metal plates 72 and a plastic plate 74 and tightened with bolts 71 and nuts 73. The clamping pressure from the top and bottom of the battery was 10 kg/m ² , and the battery was stored in a constant temperature and humidity chamber at 80° C. and RH 90 to 95% with this clamped state, and the open circuit voltage and internal resistance were examined. FIG. 6 is a diagram showing the relationship between the open circuit voltage and the storage period of the battery A of the present invention and the conventional batteries B and C. Data represent average values of n=12. As is clear from the figure, the battery A of the present invention and the conventional battery C maintained the open circuit voltage and obtained good results. On the other hand, conventional battery B has a decreased open circuit voltage. The reason for this is thought to be that even if pressure is applied from above and below the battery, shortening due to contact between lithium and the positive electrode mixture active material through the separator can be prevented. However, the separator of the conventional battery C is as thick as 120 μm, which does not satisfy the demand for a thinner battery. The reason why the battery of the present invention is good even though the separator thickness is as thin as 80μ is because two sheets of nonwoven fabric are pasted together while being rolled, so the openings in the separator are twisted and bent, and the lithium and positive electrode mixture active material can easily be mixed together. This is to prevent contact. Next, as shown in Figure 1, we compared the shot defective rate during assembly and the shoot defective rate when the battery was bent for a battery of the present invention in which the separator periphery was sandwiched between two sealing materials and a conventional battery that was not sandwiched. I investigated. The shot defective rate during assembly is the defective rate of n=100. Shoot defect rate when battery is bent is n=12
is the defective rate. In the battery bending test, the battery was bent 2,000 times in the vertical direction to R150mm, and the shot defect rate was investigated. The short circuit voltage was set to 3.0V or less.

【表】第６表より明らかなように、本発明電池は従来
電池に比べて、組立時及び電池屈曲テスト後いず
れの場合もシヨート不良は皆無であり優れてい
る。この理由は、本発明電池のセパレータは周辺
部が封口材で挟持され、かつヒートシール時の熱
により一部ぎ熱溶着して固定されているので、リ
チウムと正極合剤の接触、リチウムと正極端子板
の接触、正極合剤と負極端子板の接触が生じない
ためである。次に、正極合剤シートを電解液で処理した本発
明電池と処理しない従来電池について電池膨らみ
量を比較して調べた。第８図は正極合剤シート電解液処理温度と電池
フクラミ量の関係を示す図である。図中、Ａ、Ｂは正極合剤シートの電解液処理時
間が各々15時間、３時間である。また、電池フクラミ量は電池を80℃、RH90〜
95％に５日保存し、保存前後の電池厚みの差を以
て示した。図から明らかなように、温度が高いほど、また
処理時間が長いほど、この電池フクラミ量は小さ
くなる。この理由は、正極合剤シート中のMnO₂
表面の活性な部分が予め電解液と反応させること
により除去できるためと推定される。また、この正極合剤シートを予め電解液で処理
しない場合の電池フクラミ量は100（１mm）と大変
大きなものとなり、実使用できない。次に、電池組立後、電池を定電流で一定時間放
電する。この放電した電池を80℃、RH90〜95％
の恒温恒湿槽に保存し、開路電圧（V_pc／Ｖ）、内
部抵抗（Ri／Ω）、電池フクラミ量（△Ｈ／１＝
0.01mm）を調べた。データはｎ＝12の平均値を示
した。結果は第７表に示す。[Table] As is clear from Table 6, the battery of the present invention is superior to the conventional battery, with no shoot defects both during assembly and after the battery bending test. The reason for this is that the periphery of the separator of the battery of the present invention is sandwiched between the sealing materials and partially thermally welded and fixed by the heat during heat sealing, so the lithium and the positive electrode mix do not come into contact with each other, and the lithium and the positive electrode This is because contact between the terminal plate and the positive electrode mixture and the negative electrode terminal plate does not occur. Next, the amount of battery swelling was compared and investigated between a battery of the present invention in which the positive electrode mixture sheet was treated with an electrolytic solution and a conventional battery in which the positive electrode mixture sheet was not treated. FIG. 8 is a diagram showing the relationship between the positive electrode mixture sheet electrolyte treatment temperature and the amount of battery swelling. In the figure, A and B indicate that the electrolytic solution treatment time for the positive electrode mixture sheet was 15 hours and 3 hours, respectively. In addition, the amount of battery leakage is 80℃, RH90 ~
The battery was stored at 95% for 5 days, and the difference in battery thickness before and after storage is shown. As is clear from the figure, the higher the temperature and the longer the processing time, the smaller the amount of battery swelling becomes. The reason for this is that MnO ₂ in the positive electrode mixture sheet
It is presumed that this is because the active portions on the surface can be removed by reacting with the electrolyte in advance. Furthermore, if this positive electrode mixture sheet is not treated with an electrolytic solution in advance, the amount of battery swelling will be as large as 100 (1 mm), making it impossible to actually use it. Next, after assembling the battery, the battery is discharged at a constant current for a certain period of time. This discharged battery is heated at 80℃ and RH90~95%.
The open circuit voltage (V _pc /V), internal resistance (Ri / Ω), amount of battery swelling (△H / 1 =
0.01mm) was investigated. Data represent the average of n=12. The results are shown in Table 7.

〔Effect of the invention〕

本発明は、上述したように、シール部が二種三
層のラミネートフイルムを２枚重ねた構成とした
ため、正（負）極端子板と各ラミネートフイルム
との溶着作業を発電要素とは無関係に行うことが
できる。これに続く、発電要素を内蔵させて行う電池の
組み立ては、各端子板に溶着された同種の樹脂同
士の溶着になるので、溶着は容易で発電要素にダ
メージを与えることなく行うことができる。本来、正（負）極端子板とシール部とは、互い
に材質が互いになじみにくく溶着が困難であり、
その溶着には十分な加熱と加圧が必要である。一
方、発電要素は加熱されることにより、その性質
を劣化するおそれがあり好ましくない。すなわち、溶着の確実性と発電要素の性能維持
とは熱的に二律背反の関係にある。本発明は、このようにシール構成に二種三層の
ラミネートフイルムを２枚重ねた構成を採つたの
で、上述の二律背反の関係を避けた製造方法を採
るとができる。そのため、本発明の平板型電池はシール性に優
れた、長寿命で信頼性の高いものとなる。また、
上述したことから明らかなように、製造条件が大
幅に緩和されるので、製造も容易になる。また、本発明は封口材として水分の透湿性が少
なく、有機電活液に溶解することもなく、金属か
ら正・負極端子板との熱接着性の優れているマレ
イン酸変性ポリエチレン樹脂を用いているので、
長期間にわたつて外部からの空気、水分の侵入を
遮断できる長期信頼性を優れた電池を提供でき
る。本発明は極薄で長期信頼性に優れる平板型リチ
ウム電池を提供することができ、ICカード、薄
型電卓、時計、クリーテイングカード等に応用で
き、その工業的価値大なるものである。 As described above, the present invention has a structure in which the sealing portion is composed of two layers of two types and three layers of laminate films, so that the welding work between the positive (negative) terminal plate and each laminate film can be performed independently of the power generation element. It can be carried out. The subsequent assembly of the battery with the power generation element built in involves welding the same type of resin welded to each terminal plate, so welding is easy and can be done without damaging the power generation element. Originally, the materials of the positive (negative) terminal plate and the seal part are not compatible with each other and it is difficult to weld them together.
Sufficient heat and pressure are required for welding. On the other hand, heating the power generation element may deteriorate its properties, which is not preferable. In other words, the reliability of welding and the maintenance of the performance of the power generation element are thermally in a trade-off relationship. Since the present invention employs a structure in which two types of three-layer laminate films are stacked on top of each other in the seal structure, it is possible to adopt a manufacturing method that avoids the above-mentioned trade-offs. Therefore, the flat plate battery of the present invention has excellent sealing properties, long life, and high reliability. Also,
As is clear from the above, the manufacturing conditions are significantly relaxed, making the manufacturing easier. In addition, the present invention uses a maleic acid-modified polyethylene resin as a sealing material, which has low moisture permeability, does not dissolve in organic electroactive liquid, and has excellent thermal adhesion between metal and positive and negative electrode terminal plates. Because there are
It is possible to provide a battery with excellent long-term reliability that can block air and moisture from entering from the outside for a long period of time. The present invention can provide a flat plate lithium battery that is extremely thin and has excellent long-term reliability, and can be applied to IC cards, thin calculators, watches, cleaving cards, etc., and has great industrial value.

[Brief explanation of drawings]

第１図は本発明電池の一実施例を示す断面図、
第２図は本発明に係る封口材と電池封口部の断面
図、第３図は外形仕上げ抜を施す前後の本発明電
池の平面図と断面図、第４図は外形仕上げ抜を施
す前後の電池外周部断面図、第５図は従来電池の
外周部断面図、第６図は各種セパレータを用いた
本発明電池を保存日数と開路電圧の関係を示す
図、第７図は第６図の実験に用いたテスト治具の
断面図、第８図は正極合剤シートの電解液処理温
度と電池フクラミ量の関係を示す図である。 FIG. 1 is a sectional view showing an embodiment of the battery of the present invention;
Figure 2 is a cross-sectional view of the sealing material and battery sealing part according to the present invention, Figure 3 is a plan view and cross-sectional view of the battery of the present invention before and after external finishing punching, and Figure 4 is before and after external finishing punching. 5 is a sectional view of the outer periphery of a battery, FIG. 6 is a sectional view of the outer periphery of a conventional battery, FIG. 6 is a diagram showing the relationship between storage days and open circuit voltage of batteries of the present invention using various separators, and FIG. 7 is a sectional view of the outer periphery of a conventional battery. FIG. 8, which is a cross-sectional view of the test jig used in the experiment, is a diagram showing the relationship between the electrolyte treatment temperature of the positive electrode mixture sheet and the amount of battery swelling.

Claims

[Scope of Claims] 1. A flat plate consisting of a positive electrode terminal plate that also serves as an exterior, a positive electrode active material, a separator, an electrolyte, a negative electrode active material, a negative electrode terminal plate that also serves as an exterior, and a sealing material that seals the peripheries of the positive and negative electrode terminal plates. In the type battery, the sealing material is a two-type three-layer laminate film composed of maleic acid-modified polyethylene resin/high-density polyethylene resin/maleic acid-modified polyethylene resin,
A flat plate battery characterized by having two sheets of this sealing material placed one on top of the other. 2. The flat plate battery according to claim 1, wherein the maleic acid-modified polyethylene resin is medium density polyethylene graft-polymerized with 0.05 to 0.20% maleic acid. 3 Film thickness is maleic acid modified polyethylene
25-30μ and a high-density polyethylene resin of 50-200μ. 4. Claim 1, in which either the positive terminal plate or the negative terminal plate is drawn.
The flat plate battery according to item 2 or 3. 5. The flat plate battery according to any one of claims 1 to 4, wherein the separator is made of two layers of polypropylene nonwoven fabric. 6. The separator is a nonwoven fabric with a thickness of 60μ and a basis weight of 20g/m ² impregnated with an anionic surfactant and with a thickness of 80μ, which is obtained by stacking two sheets of non-stretched polypropylene nonwoven fabric fabricated using a micro spunbond spinning method and roll-rolling them. The flat plate battery according to item 5. 7 Claim 1, in which the peripheral portion of the separator is sandwiched and fixed between the positive electrode sealing material and the negative electrode sealing material
The flat plate battery according to any one of items 1 to 6. 8 (a) A step of welding a negative electrode sealing material, which is a two-type, three-layer laminate film composed of maleic acid-modified polyethylene resin/high-density polyethylene resin/maleic acid-modified polyethylene resin, around the inner surface of the negative electrode terminal plate, and ( b) crimping a lithium foil onto the inner surface of the negative electrode terminal plate; (c) placing a separator on the lithium; (b) placing a positive electrode active material on the separator; (e) a step of welding a positive electrode sealing material, which is a two-type, three-layer laminate film composed of maleic acid-modified polyethylene resin/high-density polyethylene resin/maleic acid-modified polyethylene resin, to the positive electrode terminal plate; (f) the positive electrode terminal; A method for manufacturing a flat plate battery comprising the steps of: placing a plate on a positive electrode active material; and (g) thermally welding the positive electrode sealing material and the negative electrode sealing material to seal a power generation element. 9. The method for manufacturing a flat battery according to claim 8, wherein the positive electrode active material is immersed in an electrolytic solution for 15 hours at 100 to 200°C for reaction treatment. 10. The method for manufacturing a flat plate battery according to claim 8, wherein the outer shape is finished and punched after the battery is assembled and sealed. 11. The method for manufacturing a flat plate battery according to claim 8 or 10, which comprises performing a discharge treatment after assembling and sealing the battery. 12. The method for manufacturing a flat plate battery according to claim 11, wherein the discharge processing amount is about 5% of the theoretical capacity of the battery. 13. The method for manufacturing a flat plate battery according to claim 12, wherein the open circuit voltage of the battery is set to 3.0 to 3.1V.