JP3852110B2

JP3852110B2 - Thin battery and manufacturing method thereof

Info

Publication number: JP3852110B2
Application number: JP2002189901A
Authority: JP
Inventors: 恭一渡邉
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2002-06-28
Filing date: 2002-06-28
Publication date: 2006-11-29
Anticipated expiration: 2022-06-28
Also published as: JP2004031288A

Description

【０００１】
【技術分野】
本発明は、封止手段の外周部の端縁から導出する端子を有する薄型電池に関し、特に印加される外力に対して強い構造を有する薄型電池に関する。
【０００２】
【背景技術】
封止手段の外周部の端縁から導出する端子を有する薄型電池の使用態様や使用条件の多様化に伴って、当該薄型電池に対して外部から印加される振動等の外力が増加する。この外力により、電池外装部材の封止部の剥離等により薄型電池内部に注入された電解液が漏洩し、当該薄型電池の性能低下を招く場合がある。
【発明の開示】
本発明は、印加される外力に対して強い構造を有する薄型電池を提供することを目的とする。
【０００３】
上記目的を達成するために、本発明によれば、少なくとも１以上の合成樹脂層を有する２枚のシート状封止手段の外周縁部を、前記合成樹脂層を熱融着する事によって発電要素を封止すると共に、前記発電要素に接続された正極端子及び負極端子が前記外周縁部から導出する薄型電池であって、前記外周縁部の熱融着領域を少なくとも２回以上熱融着する事によって前記発電要素を封止しており、各回の熱融着領域が同じ領域である薄型電池が提供される（請求項１参照）。
【０００４】
また、上記目的を達成するために、本発明によれば、少なくとも１以上の合成樹脂層を有する２枚のシート状封止手段の外周縁部の前記合成樹脂層を熱融着する事によって、発電要素を封止し、正極端子及び負極端子が外周縁部から導出する薄型電池の製造方法であって、前記封止手段の外周縁部に位置する熱融着領域で熱融着する熱融着ステップを少なくとも２以上有し、各熱融着ステップにおける熱融着領域が同じ領域である薄型電池の製造方法が提供される（請求項１８参照）。
【０００５】
本発明では、薄型電池の外周部に位置する熱融着領域を少なくとも２回以上熱融着することにより、外部から印加される外力による電池外装部材の封止部の剥離を著しく減少することが可能となり、印加される外力に対して強い構造を有する薄型電池とすることが可能となる。
【０００６】
【発明の実施の形態】
以下、本発明の実施形態を図面に基づいて説明する。
【０００７】
実施形態
図１（Ａ）は本発明の実施形態に係る薄型電池の全体を示す平面図、図１（Ｂ）は（Ａ）のII−II線に沿う断面図である。図２は図１（Ａ）のIII−III線に沿う断面図である。図３は図２のIV部の要部拡大図であり、図３（Ａ）は１回目の熱プレス後の要部拡大図、図３（Ｂ）は２回目の熱プレス後の要部拡大図、図４は本発明の実施形態に係る端子導出部応力-伸び変位グラフである。図１は一つの薄型電池（単位電池）を示し、この薄型電池１０を複数積層することにより所望の電圧、容量の組電池が構成される。
【０００８】
まず図１を参照しながら、本発明の実施形態に係る薄型電池１０の全体構成について説明すると、本例の薄型電池１０はリチウム系の薄型二次電池であり、２枚の正極板１０１と、５枚のセパレータ１０２と、２枚の負極板１０３と、正極端子１０４と、負極端子１０５と、上部電池外装部材１０６と、下部電池外装部材１０７と、特に図示しない電解質とから構成されている。このうちの正極板１０１，セパレータ１０２，負極板１０３および電解質を特に発電要素１０９と称する。
【０００９】
なお、正極板１０１，セパレータ１０２，負極板１０３の枚数には何ら限定されず、１枚の正極板１０１，３枚のセパレータ１０２，１枚の負極板１０４でも発電要素１０９を構成することができる。必要に応じて正極板、負極板およびセパレータの枚数を選択して構成することができる。
【００１０】
発電要素１０９を構成する正極板１０１は、金属酸化物などの正極活物質に、カーボンブラックなどの導電材と、ポリ四フッ化エンチレンの水性ディスパージョンなどの接着剤とを、重量比でたとえば１００：３：１０の割合で混合したものを、正極側集電体としてのアルミニウム箔などの金属箔の両面に塗着、乾燥させ、圧延したのち所定の大きさに切断したものである。なお、上記のポリ四フッ化エチレンの水性ディスパージョンの混合比率は、その固形分である。
【００１１】
正極活物質としては、例えばニッケル酸リチウム（ＬｉＮｉＯ_２）、マンガン酸リチウム（ＬｉＭｎＯ_２）、コバルト酸リチウム（ＬｉＣｏＯ_２）などのリチウム複合酸化物や、カルコゲン（Ｓ、Ｓｅ、Ｔｅ）化物を挙げることができる。これらの材質は薄型電池内部の発熱を比較的拡散し易く、端子への伝熱による端子の膨張による伸びを少なく出来、端子から後述する電池外装部材へ伝達する引張り応力を極力抑制することが可能となる。
【００１２】
発電要素１０９を構成する負極板１０３は、例えば非晶質炭素、難黒鉛化炭素、易黒鉛化炭素、または黒鉛などのように、正極活物質のリチウムイオンを吸蔵および放出する負極活物質に、有機物焼成体の前駆体材料としてのスチレンブタジエンゴム樹脂粉末の水性ディスパージョンをたとえば固形分比１００：５で混合し、乾燥させたのち粉砕することで、炭素粒子表面に炭化したスチレンブタジエンゴムを担持させたものを主材料とし、これに、アクリル樹脂エマルジョンなどの結着剤をたとえば重量比１００：５で混合し、この混合物を、負極側集電体としてのニッケル箔或いは銅箔などの金属箔の両面に塗着、乾燥させ、圧延したのち所定の大きさに切断したものである。
【００１３】
特に負極活物質として非晶質炭素や難黒鉛化炭素を用いると、充放電時における電位の平坦特性に乏しく放電量にともなって出力電圧も低下するので、通信機器や事務機器の電源には不向きであるが、電気自動車等の電源として用いると急激な出力低下がないので有利である。
【００１４】
また、発電要素１０９のセパレータ１０２は、上述した正極板１０１と負極板１０３との短絡を防止するもので、電解質を保持する機能を備えてもよい。セパレータ１０２は、例えばポリエチレン（ＰＥ）やポリプロピレン（ＰＰ）などのポリオレフィン等から構成される微多孔性膜であり、過電流が流れると、その発熱によって層の空孔が閉塞され電流を遮断する機能をも有する。
【００１５】
なお、本発明のセパレータ１０２は、ポリオレフィンなどの単層膜にのみ限られず、ポリプロピレン膜をポリエチレン膜でサンドイッチした三層構造や、ポリオレフィン微多孔膜と有機不織布などを積層したものも用いることができる。セパレータ１０２を複層化することで、過電流の防止機能、電解質保持機能およびセパレータの形状維持（剛性向上）機能などの諸機能を付与することができる。また、セパレータ１０２の代わりにゲル電解質又は真性ポリマー電解質等を用いることもできる。
【００１６】
以上の発電要素１０９は、上から正極板１０１と負極板１０３とが交互に、且つ当該正極板１０１と負極板１０３との間にセパレータ１０２が位置するような順序で積層され、さらに、その最上部及び最下部にセパレータ１０２が一枚ずつ積層されている。そして、２枚の正極板１０１のそれぞれは、正極側集電部１０４ａを介して、金属箔製の正極端子１０４に接続される一方で、２枚の負極板１０３は、負極側集電部１０５ａを介して、同じく金属箔製の負極端子１０５に接続されている。なお、正極端子１０４も負極端子１０５も電気化学的に安定した金属材料であれば特に限定されないが、正極端子１０４としてはアルミニウムやアルミニウム合金、銅又はニッケルなどを挙げることができ、負極端子１０５としてはニッケル、銅、ステンレス又は鉄などを挙げることができる。これらの金属は、金属の抵抗値、線膨張係数、抵抗率において薄型電池の構成要素として特に適当であり、使用温度を変えた場合にも、端子から後述する電池外装部材へ伝達する引張り応力を極力抑制することが可能となる。また、本例の正極側集電部１０４ａも負極側集電部１０５ａの何れも、正極板１０４および負極板１０５の集電体を構成するアルミニウム箔やニッケル箔、銅箔、鉄箔を延長して構成されているが、別途の材料や部品により当該集電部１０４ａ，１０５ａを構成することもできる。
【００１７】
発電要素１０９は、上部電池外装部材１０６及び下部電池外装部材１０７（封止手段）により封止されている。本発明の実施形態における上部電池外装部材１０６は、図３（Ａ）に示すように、薄型電池１０の内側から外側に向かって、第１の樹脂層１０６ａ、金属層１０６ｂ、第２の樹脂層１０６ｃの順で３つの層１０６ａ〜１０６ｃが積層される。この３つの層１０６ａ〜１０６ｃは、上部電池外装部材１０６の全面に渡って積層されており、第１の樹脂層１０６ａは、例えばポリエチレン、変性ポリエチレン、ポリプロピレン、変性ポリプロピレン、アイオノマーなどの耐電解液性及び熱融着性に優れた樹脂フィルムである。第２の樹脂層１０６ｃは、例えば、ポリアミド系樹脂、ポリエステル系樹脂等の電気絶縁性に優れた樹脂フィルムである。金属層１０６ｂは、例えば、アルミニウムなどの金属箔である。従って、上部電池外装部材１０６及び下部電池外装部材１０７は、例えば、アルミニウムなどの金属箔の一方の面（薄型電池の内側面）をポリエチレン、変性ポリエチレン、ポリプロピレン、変性ポリプロピレン、アイオノマーなどの樹脂でラミネートし、他方の面（薄型電池の外側面）をポリアミド系樹脂、ポリエステル系樹脂等でラミネートした、樹脂−金属薄膜ラミネート材などの可撓性を有する材料で形成される。
【００１８】
このように、電池外装部材が樹脂層に加えて金属層を具備することにより、電池外装部材の強度を向上させることが可能となる。
【００１９】
下部電池外装部材１０７は、上部電池外装部材１０６と同様の構造のものが用いられ、図３（Ａ）に示すように、薄型電池１０の内側から外側に向かって、第１の樹脂層１０７ａ、金属層１０７ｂ、第２の樹脂層１０７ｃの順で、３つの層１０７ａ〜１０７ｃが積層される。下部電池外装部材１０７の第１の樹脂層１０７ａは、上部電池外装部材１０６の第１の樹脂層１０６ａと同様に、例えばポリエチレン、変性ポリエチレン、ポリプロピレン、変性ポリプロピレン、アイオノマーなどの耐電解液性及び熱融着性に優れた樹脂フィルムである。下部電池外装部材１０７の金属層１０７ｂは、上部電池外装部材１０６の金属層１０６ｂと同様に、例えば、アルミニウムなどの金属箔である。下部電池外装部材１０７の第２の樹脂層１０７ｃは、上部電池外装部材１０６の第２の樹脂層１０６ｃと同様に、例えばポリアミド系樹脂、ポリエステル系樹脂等の電気絶縁性に優れた樹脂フィルムである。
【００２０】
以上のように、電池外装部材の内側面（薄型電池の内側面）を、ポリプロピレン、変性ポリプロピレン、ポリエチレン、変性ポリエチレン、アイオノマーなどの樹脂で構成することにより、金属からなる端子との良好な融着性を確保することが可能となる。
【００２１】
さらに、図１に示すように、封止された電池外装１０６、１０７の一方の端部から、正極端子１０４が導出するが、正極端子１０４の厚さ分だけ上部電池外装１０６と下部電池外装１０７との接合部に隙間が生じるので、薄型電池１０内の封止性を維持するために、当該正極端子１０４と電池外装１０６、１０７とが接触する部分に、ポリエチレンやポリプロピレン等から構成されたシールフィルムを熱融着などの方法により介在させることもできる。
【００２２】
同様に、封止された電池外装１０６、１０７の他方の端部からは、負極端子１０５が導出するが、ここにも正極端子１０４側と同様に、当該負極端子１０５と電池外装１０６、１０７とが接触する部分にシールフィルムを介在させることもできる。なお、正極端子１０４および負極端子１０５の何れにおいても、シールフィルムは電池外装１０６，１０７を構成する樹脂と同系統の樹脂から構成することが熱融着性の点から望ましい。
【００２３】
これらの電池外装部材１０６、１０７によって、上述した発電要素１０９、正極側集電部１０４ａ、正極端子１０４の一部、負極側集電部１０５ａおよび負極端子１０５の一部を包み込み、当該電池外装部材１０６、１０７により形成される空間に、有機液体溶媒に過塩素酸リチウム、ホウフッ化リチウム等のリチウム塩を溶質とした液体電解質を注入したのち、上部電池外装部材１０６及び下部電池外装部材１０７の外周縁の熱融着領域１１０を熱プレスにより熱融着し、封止する。
【００２４】
さらに、本発明の実施形態においては、全ての工程が終了後、即ち当該薄型電池の製造工程の最終工程において、１回目の熱プレスと同様の熱融着領域１１０に対して熱プレスにより２回目の熱融着を行う。本来ならば、１回の熱プレスで熱溶着領域１１０を熱融着を完了することが好ましい。しかし、熱融着領域１１０の断面から界面を消失させる程のプレス温度、プレス時間、プレス圧等の製造条件で一度の熱プレスを行うと、その伝熱により正極活性物質に悪影響を与えたり、電池外装部材を劣化させる場合がある。そのため、熱プレスを２回に分けて、１回目の熱プレスでは界面が存在する程度に予備的に融着を行い、最終工程において２回目の熱プレスで熱融着領域１１０の断面から界面を消失させる融着を行う。熱融着領域１１０の断面から界面を消失させることにより、当該熱融着領域１１０における破壊を、界面破壊から材料破壊へと移行させ、電池外装部材の封止部に強固な接合関係が付与される。
【００２５】
図３（Ａ）に示すように、１回目の熱プレスでは、厚さＡ_０の上部電池外装部材１０６と同様の厚さＡ_０の下部電池外装部材１０７とを熱融着領域１１０で熱融着する。図３（Ａ）に示すように、１回目の熱プレス後に、熱融着領域１１０の上部電池外装部材１０６と下部電池外装部材１０７との間には界面が存在する。
【００２６】
図３（Ｂ）に示すように、２回目の熱プレスでは、上記の１回目の熱プレスを行った熱融着領域１１０をさらに熱融着する。図３（Ｂ）に示すように、熱プレス前の電池外装部材１０６、１０７の厚さＡ_０が、２回目の熱プレス後にはその熱融着領域１１０の厚さが、熱融着領域１１０以外の領域（以下、非融着領域ともいう。）に対してＡ_１となるまで熱プレスを行う。この熱融着領域１１０の厚さＡ_１が、非融着領域の厚さＡ_０と、Ａ_１＝６０％×Ａ_０〜９０％×Ａ_０の関係を有することが好ましい。ここで、Ａ_１＜６０％×Ａ_０とすると、正極端子１０４及び負極端子１０５と、電池外装部材１０６、１０７の金属層１０６ｂのアルミニウムとが短絡するおそれがあり、Ａ_１＞９０％×Ａ_０とすると、熱融着領域１１０における上部電池外装部材１０６と下部電池外装部材１０７との間に界面が存在し、十分な融着強度を確保することが出来ない。
【００２７】
また、プレス前の上部電池外装部材１０６と下部電池外装部材１０７とがそれぞれ有する第１の樹脂層１０６ａの膜厚Ｂ_０が、２回目の熱プレス後には、熱融着領域１１０の上部電池外装部材１０６及び下部電池外装部材１０７の第１の樹脂層１０６ａが膜厚Ｂ_１となるまで熱融着を行う。この熱融着領域１１０の膜厚Ｂ_１が、非融着領域の膜厚Ｂ_０と、Ｂ_１＝０．６５×Ｂ_０〜０．８５×Ｂ_０の関係を有することが好ましい。ここで、Ｂ_１＜０．６５×Ｂ_０とすると、正極端子１０４及び負極端子１０５と、電池外装部材１０６、１０７の金属層１０６ｂのアルミニウムとが短絡するおそれがあり、Ｂ_１＞０．８５×Ｂ_０とすると、熱融着領域１１０の上部電池外装部材１０６と下部電池外装部材１０７との間に界面が存在し、十分な融着強度を確保することが出来ないためである。図３（Ｂ）に示すように、熱融着領域１１０において上部電池外装部材１０６と下部電池外装部材１０７との間の界面は消失している。
【００２８】
このように、上記のような熱融着領域領域における熱融着前後の電池外装部材の厚さ及び非融着領域の第１の樹脂層の膜厚となるような製造条件で２回の熱プレスを行うことにより、界面を消失させ、且つ薄型電池の構成要素に弊害を及ぼさないような熱融着を行うことが可能となる。図４は、正極端子及び負極端子と、電池外装部材とを引張った際の応力-伸び変位グラフであり、実線に本発明の実施形態における２回プレスを行った薄型電池の応力-伸び変位を示し、破線に１回プレスのみで作られた薄型電池の応力-変位を示す。同図に示すように、所定の条件で２回のプレスを行うことにより、薄型電池に外部から印加される振動等の外力に対して強い構造を付与することが可能となる。また、２回目の熱プレスを薄型電池の製造工程の最終工程で行うことにより、前工程中において発生している薄型電池内部の応力を極力低減することが可能となる。
【００２９】
このように封止された薄型電池１０は、総厚１〜１０［ｍｍ］を有することが好ましい。薄型電池の厚さを１０［ｍｍ］以下とすることにより、当該薄型電池内部に熱がこもりにくくなり、電池外装部材の界面に応力を伝達する可能性が低くなると共に、電池の熱劣化の影響も減少する。また、薄型電池の厚さを１［ｍｍ］以上とすることにより、十分な容量を確保することが出来、経済的な効率を高くすることが可能となる。
【００３０】
有機液体溶媒として、プロピレンカーボネート（ＰＣ）、エチレンカーボネート（ＥＣ）、ジメチルカーボネート（ＤＭＣ）などのエステル系溶媒を挙げることができるが、本発明の有機液体溶媒はこれにのみ限定されることなく、エステル系溶媒に、γ−ブチラクトン（γ−ＢＬ）、ジエトシキエタン（ＤＥＥ）等のエーテル系溶媒その他を混合、調合した有機液体溶媒も用いることができる。
【００３１】
以下に、上述の薄型電池を複数組み合わせることにより構成される組電池、及び当該組電池を複数組み合わせることにより構成される複合組電池について説明する。
【００３２】
図５は本発明の実施形態に係る複数の薄型電池の接続方法を示す図であり、図５（Ａ）は並列接続を示し、図５（Ｂ）は比較のための直列接続を示す。図６は本発明の実施形態に係る複数の薄型電池の他の接続方法を示す図であり、図６（Ａ）は並列接続を示し、図６（Ｂ）は比較のための直列接続を示す。図７は本発明の実施形態に係る複数の薄型電池により構成される組電池の斜視図、図８（Ａ）は図７の組電池の平面図、図８（Ｂ）は図７の組電池の正面図、図８（Ｃ）は図７の組電池の側面図、図９は図７の組電池より構成される複合組電池の斜視図、図１０（Ａ）は図９の複合組電池の平面図、図１０（Ｂ）は図９の複合組電池の正面図、図１０（Ｃ）は図９の複合組電池の側面図、図１１は本発明の実施形態に係る複合組電池を車両に搭載した模式図を示す。
【００３３】
上述の薄型電池１０を電気的に接続して複数の薄型電池１０を有する組電池２０を構成する場合、特に図５（Ａ）及び図６（Ａ）に示す配置による２つの接続構造が、印可される外力に対してさらに強い構造を付加する。
【００３４】
一つ目の接続構造は、図５（Ａ）に示すように、第１の薄型電池１０ａの正極端子１０４と、第２の薄型電池１０ｂの正極端子１０４とが同一方向に導出するような方向で、第１の薄型電池１０ａと第２の薄型電池１０ｂを実質的に同一平面上に並置させる。そして、第１の薄型電池１０ａの正極端子１０４と、第２の薄型電池１０ｂの正極端子１０４とを、第１のバスバー２１ａにより電気的に接続する。また、第１の薄型電池１０ａの負極端子１０５と第２の薄型電池１０ｂの負極端子１０５とを、第２のバスバー２１ｂにより電気的に接続する。
【００３５】
二つ目の接続構造は、図６（Ａ）に示すように、第１の薄型電池１０ａの正極端子１０４と、第２の薄型電池１０ｂの正極端子１０４とが同一方向に導出するような方向で、第１の薄型電池１０ａの鉛直上向きの面と第２の薄型電池１０ｂの鉛直下向きの面とを接触させて、第１の薄型電池１０ａと第２の薄型電池１０ｂとを積層する。そして、第１の薄型電池１０ａの正極端子１０４と第２の薄型電池１０ｂの正極端子１０４とを溶着して電気的に接続し、同様に、第１の薄型電池１０ａの負極端子１０５と第２の薄型電池１０ｂの負極端子１０５とを溶着して電気的に接続する。
【００３６】
図５（Ｂ）及び図６（Ｂ）に示すような直列に接続された場合、印加される外力によって、各薄型電池１０ａ、１０ｂの正極端子１０４には逆位相の捻れ（図５（Ｂ）及び図６（Ｂ）において捻れの方向を矢印により示す。）が生じるが、これに対し上記に説明した接続構造は、薄型電池１０ａ、１０ｂの正極端子１０４同士及び負極端子１０５同士が接続されているため、各薄型電池１０ａ、１０ｂに生じる応力が同位相となり、当該端子１０４、１０５に生じる捻れを極力抑えることが出来、端子と電池外装部材との間の界面に剥離が生じる可能性が低くなる。また、正極端子の金属と負極端子の金属とが異なる場合には、それに伴って、端子導出部に生ずる引張り応力も異なり界面剥離の原因になりうるが、上述の並列接続により薄型電池の端子導出部に生じる引張り応力を実質的に同等のものとすることが可能となる。
【００３７】
図７及び図８（Ａ）〜（Ｃ）は、例えば上述の２通りの接続構造を用いて並列接続された２４個の薄型電池１０から構成させる組電池２０を示す。組電池２０は、２４個の薄型電池１０と、組電池用端子２２、２３と、組電池用カバー２５とから構成されている。特に図示しないが、各薄型電池１０の各同極端子間は上述の接続構造でバスバー２１ａ、２１ｂにより並列接続されており、各正極端子１０４を接続する第１のバスバー２１ａは、組電池用カバー２５から導出する略円柱形状の組電池用正極端子２２に接続されている。同様に、各負極端子１０５を接続する第２のバスバー２１ｂは、組電池用カバー２５から導出する略円柱形状の組電池用負極端子２３に接続されている。これらの接続が完了し、２４個の薄型電池１０が組電池用カバー２５に挿入されると、当該組電池用カバー２５と当該組電池２０の他の構成要素との間に形成される空間に充填剤２４が充填され、封止される。さらに、後述する複合組電池として薄型電池が積層された際に、薄型電池同士の振動を極力低減するために、組電池用カバー２５の下面四隅に外部弾性体２６が取り付けられる。
【００３８】
図９及び図１０（Ａ）〜（Ｃ）は、図７に示す組電池２０を電気的に接続した６個の組電池２０から構成される複合組電池３０を示す。図９及び図１０（Ａ）〜（Ｃ）に示すように、複合組電池３０は、組電池２０の端子２２、２３がそれぞれ同一方向に向くように積層されている。すなわち、ｍ段目に位置する組電池２０の端子２２、２３と、ｍ＋１段目に位置する組電池２０の端子２２、２３とが同一方向に向くように、ｍ段目の組電池２０の上にｍ＋１段目の組電池２０が積層される（ｍ：自然数）。そして、同一方向を向いた全ての組電池２０の組電池用正極端子２２を、当該複合組電池３０と外部とを接続する外部接続用正極端子３１で電気的に接続する。同様に、同一方向を向いた全ての組電池２０の組電池用負極端子２３を、外部接続用負極端子３２で電気的に接続する。同図に示すように、外部接続用正極端子３１は、略矩形の平板形状であり、組電池用正極端子２２を挿入或いは圧入可能な直径を有する複数の端子接続用孔が加工されている。当該端子接続用孔は、積層された組電池２０の組電池用正極端子２２間のピッチに等しいピッチで加工されており、外部接続用負極端子３２にも同様に端子接続用孔が加工されている。
【００３９】
さらに、組電池用端子２２、２３が複合組電池３０の外部に露出しないように、接続された全ての組電池用端子２２、２３を覆うように、絶縁性の材料の絶縁カバー３３が具備されている。なお、図９において当該絶縁カバー３３は、説明の便宜上、透視図により描かれており、図１０には図示しない。そして、上述のように積層された６個の組電池２０は、その両側面部に平板状の連結部材３４で連結され、さらに固定ネジ３５により締結、固定される。
【００４０】
以上のように、薄型電池により所定の数を単位とした組電池を構成し、さらに当該組電池を単位として、所定の数の組電池を組み合わせて複合組電池を構成することにより、要求される容量、電圧等に適当な複合組電池を容易に得ることが可能となる。また、複雑な接続を伴うことなく複合組電池を構成するので、接続不良による、複合組電池の故障率を低減することが可能となる。さらに、複合組電池を構成する一つの薄型電池が故障或いは劣化し、当該薄型電池の交換を必要とする場合、当該薄型電池を有する組電池を容易に交換することも可能となる。
【００４１】
図１１は、車両１のフロア下に上述の複合組電池３０を車載した例を示す模式図である。車両１の移動に伴って、車内には多くの振動が発生する。同図に示すように、上述の複合組電池３０を車載することにより、当該振動により薄型電池の端子と電池外装部材との間に界面剥離が発生する可能性が著しく減少し、車両で電池を有効に活用することが可能となる。
【００４２】
なお、組電池を構成する薄型電池の数、複合組電池を構成する組電池の数、組電池を構成する薄型電池の接続方式、及び複合組電池を構成する組電池の接続方式は、上述の数及び接続方式に限定されるものではなく、要求される電気容量、電圧等から適宜その数及び接続方式（直列接続、並列接続、直列並列複合接続）を設定することが出来る。
【００４３】
また、以上説明した実施形態は、本発明の理解を容易にするために記載されたものであって、本発明を限定するために記載されたものではない。したがって、上記の実施形態に開示された各要素は、本発明の技術的範囲に属する全ての設計変更や均等物をも含む趣旨である。
【００４４】
【実施例】
以下、本発明をさらに具体化した実施例及び比較例により本発明の効果を確認した。以下の実施例は、上述した実施形態で用いた薄型電池の効果を確認するためのものである。
【００４５】
実施例１
実施例１の薄型電池は、高分子金属複合フィルム（ナイロン：膜厚２５μｍ、アルミニウム：膜厚４０μｍ、変性ポリプロピレン：膜厚Ｂ_０＝５０μｍ、総厚：Ａ_０＝１１５μｍ）を電池外装部材とし、変性ポリプロピレン層を封止面とした。また、正極端子にアルミニウム（Ａｌ）、負極端子にニッケル（Ｎｉ）、正極活性物物質にマンガン酸リチウム（ＬｉＭｎＯ_２）、負極活性物質に非結晶性炭素材、電解液にプロピレンカーボネート（ＰＣ）及びエチルメチルカーボネート（ＥＭＣ）の混合液を用いて、縦１４０［ｍｍ］×横８０［ｍｍ］×厚さ４［ｍｍ］の薄型電池を２回の熱プレスを行って作製した。１回目のプレスの条件は、プレス温度：２１０℃、プレス圧：５８８．４Ｎ（６０ｋｇｆ）、プレス時間：７秒である。また、２回目のプレスは、１回目の熱プレスの余熱が十分に冷えた後に、プレス温度：２１０℃、プレス圧：５８８．４Ｎ（６０ｋｇｆ）、プレス時間：７秒でおこなった。なお、２回目の熱プレス時には、正極端子及び負極端子と高分子金属複合フィルムのアルミニウム層とが短絡するのを防止するために、プレス時に融着部の設定最小厚相当の厚みを有するスペーサーを電池表面側のプレス型と裏面側のプレス型の間に介在させた。
【００４６】
この薄型電池のプレス後の熱融着領域１１０の電池外装部材の厚さは、Ａ_１＝１００μｍとなり、非融着領域に対して８７％の厚さを有した。また、プレス後の熱融着領域１１０の上部電池外装部材の金属層から下部電池外装部材までの距離は、８６μｍとなり、従って第１の樹脂層の膜厚は、Ｂ１＝８０／２μｍ＝４０μｍとなり、非融着領域に対して０．８０倍の膜厚となった。
【００４７】
この薄型電池について、引張り試験を行った。引張り試験は、薄型電池の端子と上部電池外装部材及び下部電池外装部材とをＪＩＳ・Ｋ６８３０の自動車用シーリング材試験方法に記載される引張り強さ試験方法に準拠する試験を行った。ここで、引張り試験中の伸び量を算出し、同一条件の試験での基準サンプルの伸び量との伸び比率を％で算出した。なお、引張り試験における基準サンプルは、後述する比較例１の１回の熱プレスのみで作成した薄型電池である。
【００４８】
この結果、実施例１では基準サンプルに対して３５０％の伸びの許容が確認された。さらに、図１２に実施例１の薄型電池の熱融着領域の断面写真を示すが、同図より当該熱融着領域の断面から界面が消失していることが分かる。
【００４９】
比較例１
比較例１の薄型電池のサンプルは、実施例１と同様の構造の薄型電池を１回の熱プレスのみで作製した。なお、当該１回の熱プレスの条件は、プレス温度：２１０℃、プレス圧：５８８．４Ｎ（６０ｋｇｆ）、プレス時間：７秒である。
【００５０】
この薄型電池のプレス後の熱融着領域１１０の電池外装部材の厚さは、Ａ１＝１０５μｍであり、非融着領域に対して９１％の厚さを有した。また、プレス後の熱融着領域１１０の下部電池外装部材の金属層から下部電池外装部材までの距離は、８６μｍとなり、従って、第１の樹脂層の膜厚は、Ｂ１＝８６／２μｍ＝４３μｍとなり、非融着領域に対して０．８６倍の膜厚となった。図１３に比較例１の薄型電池の熱融着領域の断面図を示すが、同図より比較例１には、当該熱融着領域の断面に界面が存在していることが分かる。なお、引張り試験における当該比較例１が基準となるため、その伸びの許容は１００％である。
【００５１】
考察
比較例１の薄型電池と比較して、実施例１の薄型電池は熱融着領域の断面から界面が消失し、引張り強度が著しく向上して、印加される外力に対して強い構造を有することが明らかとなった。
【図面の簡単な説明】
【図１】図１（Ａ）は本発明の実施形態に係る薄型電池の全体を示す平面図、図１（Ｂ）は（Ａ）のII−II線に沿う断面図である。
【図２】図１のIII−III線に沿う断面図である。
【図３】図２のIV部の要部拡大図であり、図３（Ａ）は１回目の熱プレス後の要部拡大図であり、図３（Ｂ）は２回目の熱プレス後の要部拡大図である。
【図４】本発明の実施形態に係る薄型電池の端子導出部の応力-伸び変位グラフである。
【図５】本発明の実施形態に係る複数の薄型電池の接続構造を示す図であり、図５（Ａ）は並列接続を示し、図５（Ｂ）は比較のための直列接続を示す。
【図６】本発明の実施形態に係る複数の薄型電池の他の接続構造を示す図であり、図６（Ａ）は並列接続を示し、図６（Ｂ）は比較のための直列接続を示す。
【図７】本発明の実施形態に係る複数の薄型電池により構成される組電池の斜視図である。
【図８】図８（Ａ）は図７の組電池の平面図、図８（Ｂ）は図７の組電池の正面図、図８（Ｃ）は図７の組電池の側面図である。
【図９】図７の組電池により構成される複合組電池の斜視図である。
【図１０】図１０（Ａ）は図９の複合組電池の平面図、図１０（Ｂ）は図９の複合組電池の正面図、図１０（Ｃ）は図９の複合組電池の側面図である。
【図１１】本発明の実施形態に係る複合組電池を車両に搭載した模式図である。
【図１２】実施例１の薄型電池の熱融着領域の断面写真を示す。
【図１３】比較例１の薄型電池の熱融着領域の断面写真を示す。
【符号の説明】
１…車両
１０…薄型電池
１０ａ…第１の薄型電池
１０ｂ…第２の薄型電池
１０１…正極板
１０２…セパレータ
１０３…負極板
１０４…正極端子
１０５…負極端子
１０６…上部電池外装部材
１０７…下部電池外装部材
１０９…発電要素
１１０…熱融着領域
２０…組電池
２１ａ…第１のバスバー
２１ｂ…第２のバスバー
２２…組電池用正極端子
２３…組電池用負極端子
２４…充填剤
２５…組電池用カバー
２６…外部弾性体
３０…複合組電池
３１…外部接続用正極端子
３２…外部接続用負極端子
３３…絶縁カバー
３４…連結部材
３５…固定ネジ
Ａ０…非融着領域の電池外装部材の厚さ
Ａ１…プレス後の熱融着領域の電池外装部材の厚さ
Ｂ０…非融着領域の第１の樹脂層の膜厚
Ｂ１…プレス後の熱融着領域の第１の樹脂層の膜厚[0001]
【Technical field】
The present invention relates to a thin battery having a terminal led out from an edge of an outer peripheral portion of a sealing means, and more particularly to a thin battery having a structure strong against an applied external force.
[0002]
[Background]
With the diversification of usage modes and usage conditions of thin batteries having terminals led out from the edge of the outer peripheral portion of the sealing means, external forces such as vibrations applied from the outside to the thin batteries increase. Due to this external force, the electrolyte injected into the thin battery may leak due to peeling of the sealing portion of the battery exterior member, and the performance of the thin battery may be reduced.
DISCLOSURE OF THE INVENTION
An object of this invention is to provide the thin battery which has a structure strong with respect to the applied external force.
[0003]
In order to achieve the above object, according to the present invention, a power generation element is obtained by heat-sealing the outer peripheral edge of two sheet-like sealing means having at least one or more synthetic resin layers. A thin battery in which a positive electrode terminal and a negative electrode terminal connected to the power generation element are led out from the outer peripheral edge portion, and a heat fusion region of the outer peripheral edge portionTheHeat fusion at least twiceYouSealing the power generation elementAnd each time the heat-sealed area is the same areaA thin battery is provided (see claim 1).
[0004]
Moreover, in order to achieve the said objective, according to this invention, the outer-periphery edge part of the sheet-shaped sealing means of 2 sheets which has at least 1 or more synthetic resin layersofA method for manufacturing a thin battery in which a power generation element is sealed by heat-sealing the synthetic resin layer, and a positive electrode terminal and a negative electrode terminal are led out from an outer peripheral edge portion, and is positioned at the outer peripheral edge portion of the sealing means. Have at least two heat fusion steps for heat fusion in the heat fusion regionIn addition, the heat fusion region in each heat fusion step is the same regionA method for manufacturing a thin battery is provided (see claim 18).
[0005]
In the present invention, peeling of the sealing portion of the battery exterior member due to external force applied from the outside can be significantly reduced by heat-sealing the heat-sealing region located on the outer peripheral portion of the thin battery at least twice. Thus, a thin battery having a structure strong against an applied external force can be obtained.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0007]
Embodiment
FIG. 1A is a plan view showing an entire thin battery according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line II-II in FIG. FIG. 2 is a sectional view taken along line III-III in FIG. 3 is an enlarged view of the main part of the IV part of FIG. 2, FIG. 3 (A) is an enlarged view of the main part after the first hot press, and FIG. 3 (B) is an enlarged main part after the second hot press. FIG. 4 and FIG. 4 are terminal lead-out portion stress-elongation displacement graphs according to the embodiment of the present invention. FIG. 1 shows one thin battery (unit battery), and an assembled battery having a desired voltage and capacity is formed by stacking a plurality of thin batteries 10.
[0008]
First, the overall configuration of the thin battery 10 according to the embodiment of the present invention will be described with reference to FIG. 1. The thin battery 10 of this example is a lithium-based thin secondary battery, and includes two positive electrode plates 101, It comprises five separators 102, two negative plates 103, a positive terminal 104, a negative terminal 105, an upper battery outer member 106, a lower battery outer member 107, and an electrolyte (not shown). Among these, the positive electrode plate 101, the separator 102, the negative electrode plate 103, and the electrolyte are particularly referred to as a power generation element 109.
[0009]
The number of positive plates 101, separators 102, and negative plates 103 is not limited in any way, and the power generation element 109 can be configured with one positive plate 101, three separators 102, and one negative plate 104. . The number of positive electrode plates, negative electrode plates, and separators can be selected and configured as necessary.
[0010]
The positive electrode plate 101 that constitutes the power generation element 109 includes, for example, 100 weight ratio of a positive electrode active material such as a metal oxide, a conductive material such as carbon black, and an adhesive such as an aqueous dispersion of polytetrafluoroethylene. : A mixture of 3:10 is applied to both surfaces of a metal foil such as an aluminum foil as a positive electrode side current collector, dried, rolled, and then cut into a predetermined size. In addition, the mixing ratio of said aqueous dispersion of polytetrafluoroethylene is the solid content.
[0011]
As the positive electrode active material, for example, lithium nickelate (LiNiO)₂), Lithium manganate (LiMnO)₂), Lithium cobaltate (LiCoO)₂) And the like, and chalcogen (S, Se, Te) compounds. These materials are relatively easy to diffuse the heat generated inside the thin battery, can reduce the expansion caused by the expansion of the terminal due to the heat transfer to the terminal, and can suppress the tensile stress transmitted from the terminal to the battery exterior member described later as much as possible. It becomes.
[0012]
The negative electrode plate 103 constituting the power generation element 109 is made of a negative electrode active material that occludes and releases lithium ions of the positive electrode active material, such as amorphous carbon, non-graphitizable carbon, graphitizable carbon, or graphite. An aqueous dispersion of styrene butadiene rubber resin powder as a precursor material of an organic fired body is mixed at a solid content ratio of, for example, 100: 5, dried and then pulverized to support carbonized styrene butadiene rubber on the surface of carbon particles The resulting material is mixed with a binder such as an acrylic resin emulsion at a weight ratio of, for example, 100: 5, and this mixture is used as a metal foil such as nickel foil or copper foil as a negative electrode side current collector. These are coated on both sides, dried, rolled, and then cut into a predetermined size.
[0013]
In particular, when amorphous carbon or non-graphitizable carbon is used as the negative electrode active material, the flatness of the potential during charge / discharge is poor and the output voltage decreases with the amount of discharge. However, when used as a power source for an electric vehicle or the like, it is advantageous because there is no sudden drop in output.
[0014]
In addition, the separator 102 of the power generation element 109 prevents a short circuit between the positive electrode plate 101 and the negative electrode plate 103 described above, and may have a function of holding an electrolyte. The separator 102 is a microporous film made of polyolefin such as polyethylene (PE) or polypropylene (PP), for example. When an overcurrent flows, the pores of the layer are blocked by the heat generation, thereby blocking the current. It also has.
[0015]
The separator 102 of the present invention is not limited to a single-layer film such as polyolefin, but a three-layer structure in which a polypropylene film is sandwiched with a polyethylene film, or a laminate of a polyolefin microporous film and an organic nonwoven fabric can be used. . By forming the separator 102 in multiple layers, various functions such as an overcurrent prevention function, an electrolyte holding function, and a separator shape maintenance (rigidity improvement) function can be provided. Further, instead of the separator 102, a gel electrolyte or an intrinsic polymer electrolyte can be used.
[0016]
The above power generation element 109 is laminated in such an order that the positive electrode plate 101 and the negative electrode plate 103 are alternately arranged from above and the separator 102 is positioned between the positive electrode plate 101 and the negative electrode plate 103. The separators 102 are stacked one by one on the top and bottom. Each of the two positive plates 101 is connected to the positive terminal 104 made of metal foil via the positive current collector 104a, while the two negative plates 103 are connected to the negative current collector 105a. Is connected to the negative electrode terminal 105 which is also made of metal foil. The positive electrode terminal 104 and the negative electrode terminal 105 are not particularly limited as long as they are electrochemically stable metal materials. Examples of the positive electrode terminal 104 include aluminum, an aluminum alloy, copper, and nickel. Can include nickel, copper, stainless steel or iron. These metals are particularly suitable as components of thin batteries in terms of the resistance value, linear expansion coefficient, and resistivity of the metal, and even when the operating temperature is changed, the tensile stress transmitted from the terminal to the battery exterior member described later is transmitted. It is possible to suppress as much as possible. Further, both the positive electrode side current collector 104a and the negative electrode side current collector 105a in this example extend the aluminum foil, nickel foil, copper foil, and iron foil constituting the current collector of the positive electrode plate 104 and the negative electrode plate 105. However, the current collectors 104a and 105a can be formed of separate materials and parts.
[0017]
The power generation element 109 is sealed by the upper battery exterior member 106 and the lower battery exterior member 107 (sealing means). As shown in FIG. 3A, the upper battery exterior member 106 in the embodiment of the present invention includes a first resin layer 106a, a metal layer 106b, and a second resin layer from the inside to the outside of the thin battery 10. Three layers 106a to 106c are stacked in the order of 106c. The three layers 106a to 106c are laminated over the entire surface of the upper battery exterior member 106, and the first resin layer 106a is resistant to an electrolytic solution such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, and ionomer. And a resin film excellent in heat-fusibility. The second resin layer 106c is a resin film excellent in electrical insulation, such as a polyamide resin or a polyester resin. The metal layer 106b is, for example, a metal foil such as aluminum. Therefore, the upper battery exterior member 106 and the lower battery exterior member 107 are laminated with a resin such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, or ionomer on one surface (inner surface of a thin battery) of a metal foil such as aluminum. Then, the other surface (the outer surface of the thin battery) is formed of a flexible material such as a resin-metal thin film laminate material in which a polyamide resin, a polyester resin, or the like is laminated.
[0018]
Thus, when the battery exterior member includes the metal layer in addition to the resin layer, the strength of the battery exterior member can be improved.
[0019]
The lower battery exterior member 107 has the same structure as the upper battery exterior member 106, and as shown in FIG. 3A, the first resin layer 107a, Three layers 107a to 107c are stacked in the order of the metal layer 107b and the second resin layer 107c. Similar to the first resin layer 106a of the upper battery exterior member 106, the first resin layer 107a of the lower battery exterior member 107 is resistant to electrolyte solution and heat such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, and ionomer. It is a resin film excellent in fusing property. The metal layer 107b of the lower battery exterior member 107 is, for example, a metal foil such as aluminum, like the metal layer 106b of the upper battery exterior member 106. Similar to the second resin layer 106c of the upper battery exterior member 106, the second resin layer 107c of the lower battery exterior member 107 is a resin film excellent in electrical insulation, such as a polyamide resin or a polyester resin. .
[0020]
As described above, by forming the inner surface of the battery exterior member (the inner surface of the thin battery) with a resin such as polypropylene, modified polypropylene, polyethylene, modified polyethylene, or ionomer, it is possible to achieve good fusion with a metal terminal. It becomes possible to ensure the sex.
[0021]
Further, as shown in FIG. 1, the positive terminal 104 is led out from one end of the sealed battery casings 106 and 107, but the upper battery casing 106 and the lower battery casing 107 are equivalent to the thickness of the positive terminal 104. In order to maintain the sealing performance in the thin battery 10, a seal made of polyethylene, polypropylene, or the like is provided at a portion where the positive electrode terminal 104 and the battery exterior 106, 107 are in contact with each other. The film can be interposed by a method such as heat fusion.
[0022]
Similarly, the negative electrode terminal 105 is led out from the other end of the sealed battery casings 106 and 107, and here, similarly to the positive terminal 104 side, the negative electrode terminal 105 and the battery casings 106 and 107 It is also possible to interpose a seal film at the portion where the contacts. In any of the positive electrode terminal 104 and the negative electrode terminal 105, it is desirable from the viewpoint of heat-sealability that the seal film is made of a resin of the same system as the resin constituting the battery casings 106 and 107.
[0023]
The battery exterior members 106 and 107 enclose the power generation element 109, the positive current collector 104a, a part of the positive terminal 104, the negative current collector 105a, and a part of the negative terminal 105, and the battery exterior member. After injecting a liquid electrolyte having a lithium salt such as lithium perchlorate and lithium borofluoride into an organic liquid solvent into the space formed by 106, 107, the outer surfaces of the upper battery outer member 106 and the lower battery outer member 107 are removed. The peripheral heat-sealed region 110 is heat-sealed by hot pressing and sealed.
[0024]
Furthermore, in the embodiment of the present invention, after all the steps are completed, that is, in the final step of the manufacturing process of the thin battery, the heat fusion region 110 similar to the first hot press is subjected to the second hot press. Perform heat fusion. Originally, it is preferable to complete the heat-sealing of the heat-welding region 110 by one hot press. However, if a single heat press is performed under manufacturing conditions such as a press temperature, a press time, and a press pressure that cause the interface to disappear from the cross section of the heat fusion region 110, the positive electrode active material is adversely affected by the heat transfer, The battery exterior member may be deteriorated. Therefore, the heat press is divided into two times, and the first heat press is preliminarily fused to the extent that the interface exists, and in the final step, the interface is viewed from the cross section of the heat fusion region 110 by the second heat press. Perform fusion to eliminate. By erasing the interface from the cross section of the heat fusion region 110, the destruction in the heat fusion region 110 is shifted from the interface failure to the material failure, and a strong bonding relationship is given to the sealing portion of the battery exterior member. The
[0025]
As shown in FIG. 3A, in the first hot press, the thickness A₀The same thickness A as the upper battery exterior member 106 of₀The lower battery exterior member 107 is heat-sealed in the heat-sealing region 110. As shown in FIG. 3A, an interface exists between the upper battery outer member 106 and the lower battery outer member 107 in the heat-sealing region 110 after the first hot pressing.
[0026]
As shown in FIG. 3B, in the second heat press, the heat-sealed region 110 subjected to the first heat press is further heat-sealed. As shown in FIG. 3B, the thickness A of the battery exterior members 106 and 107 before hot pressing₀However, after the second hot pressing, the thickness of the heat-sealed region 110 is A with respect to a region other than the heat-fused region 110 (hereinafter also referred to as a non-fused region).₁Heat press until The thickness A of the heat-sealing region 110₁Is the thickness A of the non-fused region.₀And A₁= 60% x A₀~ 90% × A₀It is preferable to have the following relationship. Where A₁<60% x A₀Then, the positive electrode terminal 104 and the negative electrode terminal 105 and the aluminum of the metal layer 106b of the battery exterior members 106 and 107 may be short-circuited.₁> 90% x A₀Then, an interface exists between the upper battery exterior member 106 and the lower battery exterior member 107 in the heat fusion region 110, and sufficient fusion strength cannot be ensured.
[0027]
Further, the thickness B of the first resin layer 106a included in each of the upper battery outer member 106 and the lower battery outer member 107 before pressing is provided.₀However, after the second heat press, the first resin layer 106a of the upper battery exterior member 106 and the lower battery exterior member 107 in the heat fusion region 110 has a film thickness B.₁Heat fusion is performed until Film thickness B of this heat-sealed region 110₁Is the film thickness B in the non-fused region.₀And B₁= 0.65 x B₀~ 0.85 × B₀It is preferable to have the following relationship. Where B₁<0.65 × B₀Then, the positive electrode terminal 104 and the negative electrode terminal 105 may be short-circuited with the aluminum of the metal layer 106b of the battery exterior members 106 and 107, and B₁> 0.85 × B₀This is because an interface exists between the upper battery exterior member 106 and the lower battery exterior member 107 in the heat fusion region 110, and sufficient fusion strength cannot be ensured. As shown in FIG. 3B, the interface between the upper battery outer member 106 and the lower battery outer member 107 disappears in the heat fusion region 110.
[0028]
As described above, the heat is applied twice under the production conditions such that the thickness of the battery exterior member before and after the thermal fusion in the thermal fusion region and the thickness of the first resin layer in the non-fusion region are as described above. By performing the pressing, it is possible to perform heat fusion so that the interface disappears and the components of the thin battery are not adversely affected. FIG. 4 is a stress-elongation displacement graph when the positive electrode terminal, the negative electrode terminal, and the battery exterior member are pulled. The solid line shows the stress-elongation displacement of the thin battery that was pressed twice in the embodiment of the present invention. The broken line shows the stress-displacement of a thin battery made only by pressing once. As shown in the figure, by performing the pressing twice under a predetermined condition, it becomes possible to give the thin battery a structure strong against external force such as vibration applied from the outside. Further, by performing the second hot pressing in the final step of the manufacturing process of the thin battery, it is possible to reduce the stress inside the thin battery generated in the previous process as much as possible.
[0029]
The thin battery 10 thus sealed preferably has a total thickness of 1 to 10 [mm]. By setting the thickness of the thin battery to 10 [mm] or less, it becomes difficult for heat to be accumulated inside the thin battery, the possibility of transmitting stress to the interface of the battery exterior member is reduced, and the influence of the thermal deterioration of the battery Also decreases. Further, by setting the thickness of the thin battery to 1 [mm] or more, a sufficient capacity can be ensured, and economic efficiency can be increased.
[0030]
Examples of the organic liquid solvent include ester solvents such as propylene carbonate (PC), ethylene carbonate (EC), and dimethyl carbonate (DMC), but the organic liquid solvent of the present invention is not limited thereto, An organic liquid solvent prepared by mixing and preparing an ether solvent such as γ-butylactone (γ-BL) and dietoshikiethane (DEE) in an ester solvent can also be used.
[0031]
Hereinafter, an assembled battery configured by combining a plurality of the above-described thin batteries and a composite assembled battery configured by combining a plurality of the assembled batteries will be described.
[0032]
5A and 5B are diagrams showing a method for connecting a plurality of thin batteries according to an embodiment of the present invention. FIG. 5A shows parallel connection, and FIG. 5B shows serial connection for comparison. 6A and 6B are diagrams showing another connection method of a plurality of thin batteries according to the embodiment of the present invention. FIG. 6A shows parallel connection and FIG. 6B shows serial connection for comparison. . 7 is a perspective view of an assembled battery including a plurality of thin batteries according to an embodiment of the present invention, FIG. 8A is a plan view of the assembled battery of FIG. 7, and FIG. 8B is an assembled battery of FIG. FIG. 8C is a side view of the assembled battery of FIG. 7, FIG. 9 is a perspective view of a composite assembled battery composed of the assembled battery of FIG. 7, and FIG. 10A is the composite assembled battery of FIG. 10 (B) is a front view of the composite battery pack of FIG. 9, FIG. 10 (C) is a side view of the composite battery pack of FIG. 9, and FIG. 11 shows the composite battery pack according to the embodiment of the present invention. The schematic diagram mounted in the vehicle is shown.
[0033]
When the assembled battery 20 having the plurality of thin batteries 10 is configured by electrically connecting the thin batteries 10 described above, two connection structures having the arrangements shown in FIGS. 5A and 6A are particularly applicable. A structure that is stronger against external force is added.
[0034]
As shown in FIG. 5A, the first connection structure is a direction in which the positive terminal 104 of the first thin battery 10a and the positive terminal 104 of the second thin battery 10b are led out in the same direction. Thus, the first thin battery 10a and the second thin battery 10b are juxtaposed on substantially the same plane. Then, the positive terminal 104 of the first thin battery 10a and the positive terminal 104 of the second thin battery 10b are electrically connected by the first bus bar 21a. Further, the negative terminal 105 of the first thin battery 10a and the negative terminal 105 of the second thin battery 10b are electrically connected by the second bus bar 21b.
[0035]
In the second connection structure, as shown in FIG. 6A, the positive terminal 104 of the first thin battery 10a and the positive terminal 104 of the second thin battery 10b are led out in the same direction. Thus, the first thin battery 10a and the second thin battery 10b are stacked by bringing the vertically upward surface of the first thin battery 10a into contact with the vertically downward surface of the second thin battery 10b. Then, the positive electrode terminal 104 of the first thin battery 10a and the positive electrode terminal 104 of the second thin battery 10b are welded and electrically connected, and similarly, the negative electrode terminal 105 of the first thin battery 10a and the second terminal The thin-film battery 10b is electrically connected to the negative electrode terminal 105 by welding.
[0036]
When connected in series as shown in FIG. 5 (B) and FIG. 6 (B), the positive terminal 104 of each thin battery 10a, 10b is twisted in the opposite phase by the applied external force (FIG. 5 (B)). 6 (B), the direction of twisting is indicated by an arrow.) However, in the connection structure described above, the positive terminals 104 and the negative terminals 105 of the thin batteries 10a and 10b are connected to each other. Therefore, the stresses generated in the thin batteries 10a and 10b are in the same phase, the twist generated in the terminals 104 and 105 can be suppressed as much as possible, and the possibility that the interface between the terminals and the battery exterior member is peeled off is low. Become. In addition, if the metal of the positive electrode terminal and the metal of the negative electrode terminal are different, the tensile stress generated in the terminal lead-out portion may be different and cause interfacial delamination. It is possible to substantially equalize the tensile stress generated in the part.
[0037]
FIGS. 7 and 8A to 8C show an assembled battery 20 composed of 24 thin batteries 10 connected in parallel using, for example, the above-described two connection structures. The assembled battery 20 includes 24 thin batteries 10, assembled battery terminals 22 and 23, and an assembled battery cover 25. Although not shown in particular, the same-polarity terminals of each thin battery 10 are connected in parallel by the bus bars 21a and 21b in the above-described connection structure, and the first bus bar 21a connecting each positive terminal 104 is an assembled battery cover. 25 is connected to a substantially cylindrical assembled battery positive electrode terminal 22 led out from 25. Similarly, the second bus bar 21 b connecting each negative electrode terminal 105 is connected to a substantially cylindrical assembled battery negative terminal 23 that is led out from the assembled battery cover 25. When these connections are completed and 24 thin batteries 10 are inserted into the assembled battery cover 25, a space formed between the assembled battery cover 25 and the other components of the assembled battery 20 is formed. Filler 24 is filled and sealed. Furthermore, when thin batteries are stacked as a composite battery pack, which will be described later, in order to reduce vibration between the thin batteries as much as possible, external elastic bodies 26 are attached to the bottom four corners of the battery pack cover 25.
[0038]
FIGS. 9 and 10A to 10C show a composite battery pack 30 including six battery packs 20 electrically connected to the battery pack 20 shown in FIG. As shown in FIG. 9 and FIGS. 10A to 10C, the composite battery pack 30 is stacked such that the terminals 22 and 23 of the battery pack 20 face in the same direction. That is, the terminals 22 and 23 of the assembled battery 20 located at the m-th stage and the terminals 22 and 23 of the assembled battery 20 located at the (m + 1) -th stage are oriented in the same direction. M + 1-stage assembled batteries 20 are stacked (m: natural number). Then, the assembled battery positive terminals 22 of all assembled batteries 20 facing in the same direction are electrically connected by the external connection positive terminal 31 that connects the composite assembled battery 30 and the outside. Similarly, the assembled battery negative terminals 23 of all assembled batteries 20 facing in the same direction are electrically connected by the external connection negative terminal 32. As shown in the figure, the external connection positive electrode terminal 31 has a substantially rectangular flat plate shape, and a plurality of terminal connection holes having a diameter into which the assembled battery positive electrode terminal 22 can be inserted or press-fitted are processed. The terminal connection holes are processed at a pitch equal to the pitch between the assembled battery positive terminals 22 of the stacked assembled battery 20, and the terminal connection holes are similarly processed in the external connection negative terminal 32. Yes.
[0039]
Further, an insulating cover 33 made of an insulating material is provided so as to cover all the connected assembled battery terminals 22 and 23 so that the assembled battery terminals 22 and 23 are not exposed to the outside of the composite assembled battery 30. ing. In FIG. 9, the insulating cover 33 is drawn as a perspective view for convenience of explanation, and is not shown in FIG. Then, the six assembled batteries 20 stacked as described above are connected to both side surfaces by flat connecting members 34 and further fastened and fixed by fixing screws 35.
[0040]
As described above, it is required that a battery pack is formed in units of a predetermined number of thin batteries, and further a battery pack is combined with a predetermined number of battery packs in units of the battery pack. It becomes possible to easily obtain a composite battery pack suitable for capacity, voltage and the like. In addition, since the composite battery pack is configured without complicated connection, the failure rate of the composite battery pack due to poor connection can be reduced. Furthermore, when one thin battery constituting the composite assembled battery fails or deteriorates and the thin battery needs to be replaced, the assembled battery having the thin battery can be easily replaced.
[0041]
FIG. 11 is a schematic diagram illustrating an example in which the above-described composite assembled battery 30 is mounted on the vehicle 1 below the floor. As the vehicle 1 moves, a lot of vibration is generated in the vehicle. As shown in the figure, when the above-described composite assembled battery 30 is mounted on the vehicle, the possibility of interface peeling between the terminals of the thin battery and the battery exterior member due to the vibration is significantly reduced. It can be used effectively.
[0042]
The number of thin batteries constituting the assembled battery, the number of assembled batteries constituting the composite battery, the connection method of the thin batteries constituting the assembled battery, and the connection method of the assembled batteries constituting the composite battery are described above. The number and connection method are not limited, and the number and connection method (series connection, parallel connection, series-parallel composite connection) can be appropriately set based on required electric capacity, voltage, and the like.
[0043]
The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.
[0044]
【Example】
Hereinafter, the effects of the present invention were confirmed by examples and comparative examples that further embody the present invention. The following examples are for confirming the effects of the thin battery used in the above-described embodiment.
[0045]
Example 1
The thin battery of Example 1 is a polymer metal composite film (nylon: film thickness 25 μm, aluminum: film thickness 40 μm, modified polypropylene: film thickness B₀= 50 μm, total thickness: A₀= 115 μm) was used as the battery exterior member, and the modified polypropylene layer was used as the sealing surface. In addition, aluminum (Al) for the positive electrode terminal, nickel (Ni) for the negative electrode terminal, lithium manganate (LiMnO) for the positive electrode active material₂), Using a non-crystalline carbon material for the negative electrode active material, and a mixed solution of propylene carbonate (PC) and ethyl methyl carbonate (EMC) for the electrolyte solution, length 140 [mm] × width 80 [mm] × thickness 4 [ mm] thin battery was manufactured by performing two hot presses. The conditions of the first press are: press temperature: 210 ° C., press pressure: 588.4 N (60 kgf), press time: 7 seconds. The second press was performed at a press temperature of 210 ° C., a press pressure of 588.4 N (60 kgf), and a press time of 7 seconds after the remaining heat of the first hot press was sufficiently cooled. In the second hot pressing, a spacer having a thickness equivalent to the minimum set thickness of the fusion part is pressed at the time of pressing in order to prevent the positive electrode terminal and the negative electrode terminal and the aluminum layer of the polymer metal composite film from being short-circuited. It was interposed between the press die on the battery front side and the press die on the back side.
[0046]
The thickness of the battery exterior member in the heat fusion region 110 after pressing the thin battery is A₁= 100 μm, having a thickness of 87% with respect to the non-fused region. Further, the distance from the metal layer of the upper battery outer member to the lower battery outer member in the heat-bonding region 110 after pressing is 86 μm, and therefore the thickness of the first resin layer is B1 = 80/2 μm = 40 μm. The film thickness was 0.80 times that of the non-fused region.
[0047]
This thin battery was subjected to a tensile test. In the tensile test, the terminal of the thin battery, the upper battery exterior member, and the lower battery exterior member were tested in accordance with the tensile strength test method described in the automotive sealing material test method of JIS K6830. Here, the elongation amount during the tensile test was calculated, and the elongation ratio relative to the elongation amount of the reference sample in the test under the same conditions was calculated in%. In addition, the reference | standard sample in a tension test is a thin battery created only by one hot press of the comparative example 1 mentioned later.
[0048]
As a result, in Example 1, it was confirmed that the elongation of 350% with respect to the reference sample was acceptable. Further, FIG. 12 shows a cross-sectional photograph of the heat-sealed region of the thin battery of Example 1, and it can be seen from FIG.
[0049]
Comparative Example 1
As a sample of the thin battery of Comparative Example 1, a thin battery having the same structure as that of Example 1 was produced by only one hot press. In addition, the conditions of the said 1 time hot press are press temperature: 210 degreeC, press pressure: 588.4N (60 kgf), and press time: 7 second.
[0050]
The thickness of the battery exterior member in the heat-sealed region 110 after pressing of this thin battery was A1 = 105 μm, and the thickness was 91% with respect to the non-fused region. Further, the distance from the metal layer of the lower battery exterior member to the lower battery exterior member in the heat-sealed region 110 after pressing is 86 μm, and therefore the film thickness of the first resin layer is B1 = 86/2 μm = 43 μm. Thus, the film thickness was 0.86 times that of the non-fused region. FIG. 13 shows a cross-sectional view of the heat-sealed region of the thin battery of Comparative Example 1. It can be seen from FIG. 13 that Comparative Example 1 has an interface in the cross-section of the heat-welded region. In addition, since the said comparative example 1 in a tension test becomes a reference | standard, the tolerance of the elongation is 100%.
[0051]
Consideration
Compared with the thin battery of Comparative Example 1, the thin battery of Example 1 has a structure in which the interface disappears from the cross section of the heat-sealed region, the tensile strength is remarkably improved, and it is strong against the applied external force. Became clear.
[Brief description of the drawings]
FIG. 1A is a plan view showing an entire thin battery according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line II-II in FIG.
FIG. 2 is a cross-sectional view taken along line III-III in FIG.
3 is an enlarged view of the main part of the IV part of FIG. 2, FIG. 3 (A) is an enlarged view of the main part after the first hot press, and FIG. 3 (B) is a view after the second hot press. It is a principal part enlarged view.
FIG. 4 is a stress-elongation displacement graph of a terminal lead-out portion of the thin battery according to the embodiment of the present invention.
5A and 5B are diagrams showing a connection structure of a plurality of thin batteries according to an embodiment of the present invention, where FIG. 5A shows parallel connection and FIG. 5B shows serial connection for comparison.
6A and 6B are diagrams showing another connection structure of a plurality of thin batteries according to an embodiment of the present invention, where FIG. 6A shows parallel connection and FIG. 6B shows serial connection for comparison. Show.
FIG. 7 is a perspective view of an assembled battery including a plurality of thin batteries according to an embodiment of the present invention.
8A is a plan view of the assembled battery of FIG. 7, FIG. 8B is a front view of the assembled battery of FIG. 7, and FIG. 8C is a side view of the assembled battery of FIG. .
FIG. 9 is a perspective view of a composite assembled battery including the assembled battery of FIG.
10A is a plan view of the composite battery pack of FIG. 9, FIG. 10B is a front view of the composite battery pack of FIG. 9, and FIG. 10C is a side view of the composite battery pack of FIG. FIG.
FIG. 11 is a schematic diagram in which a composite battery pack according to an embodiment of the present invention is mounted on a vehicle.
12 shows a cross-sectional photograph of the heat-sealed region of the thin battery of Example 1. FIG.
13 shows a cross-sectional photograph of the heat-sealed region of the thin battery of Comparative Example 1. FIG.
[Explanation of symbols]
1 ... Vehicle
10 ... Thin battery
10a: first thin battery
10b ... second thin battery
101 ... Positive electrode plate
102 ... Separator
103 ... Negative electrode plate
104: Positive terminal
105 ... Negative electrode terminal
106: Upper battery exterior member
107 ... Lower battery exterior member
109 ... Power generation element
110 ... heat fusion region
20 ... Battery
21a ... first bus bar
21b ... second bus bar
22 ... Positive electrode terminal for battery pack
23 ... Negative electrode terminal for battery pack
24 ... Filler
25 ... Battery cover
26. External elastic body
30 ... Composite battery pack
31 ... Positive terminal for external connection
32 ... Negative terminal for external connection
33 ... Insulation cover
34. Connecting member
35 ... Fixing screw
A0: thickness of the battery exterior member in the non-fused region
A1: Thickness of the battery exterior member in the heat fusion region after pressing
B0: Film thickness of the first resin layer in the non-fused region
B1: Film thickness of the first resin layer in the heat-sealed region after pressing

Claims

While sealing the power generating element by thermally fusing the synthetic resin layer to the outer peripheral edge of the two sheet-like sealing means having at least one synthetic resin layer,
A thin battery in which a positive terminal and a negative terminal connected to the power generation element are led out from the outer peripheral edge,
Has sealing the power generating element by you heat sealing at least twice the heat Chakuryoiki of the outer periphery, thin battery each time the thermal fusion region is the same region.

The thickness after thermal fusion of the sealing means in the thermal fusion region is 60 to 90% with respect to the thickness of the sealing means in a non-fusion region, which is a region not thermally fused. 1. A thin battery according to 1.

The thickness after thermal fusion of the synthetic resin layer located in the thermal fusion region is
The thin battery according to claim 1 or 2, wherein the thickness is 0.65 to 0.85 times the thickness of the synthetic resin layer located in the non-thermal fusion region.

The thin battery according to claim 1, wherein the sealing unit further includes at least one metal layer.

The thin battery according to any one of claims 1 to 4, wherein the synthetic resin layer includes a material selected from the group consisting of polypropylene, modified polypropylene, polyethylene, modified polyethylene, or ionomer.

The thin battery according to claim 1, wherein the positive terminal includes one or more components selected from the group consisting of aluminum, copper , and nickel.

The thin battery according to claim 1, wherein the negative electrode terminal includes one or more components selected from the group consisting of iron, nickel, and copper.

The thin battery according to any one of claims 1 to 7, wherein the thin battery has a thickness of 1 to 10 mm.

The power generation element has a positive electrode active material that functions as a positive electrode,
The thin battery according to any one of claims 1 to 8, wherein the positive electrode active material is a lithium composite oxide.

The thin battery according to claim 9, wherein the lithium composite oxide is a lithium-manganese composite oxide.

The power generation element has a negative electrode active material that functions as a negative electrode,
The thin battery according to claim 1, wherein the negative electrode active material is a carbon-based material.

The thin battery according to claim 11, wherein the carbon-based material is an amorphous carbon material.

A plurality of the thin batteries according to any one of claims 1 to 12,
A battery assembly having a plurality of connecting means for electrically connecting one of the positive electrode terminal or the negative electrode terminal of one thin battery and the same polarity terminal or one of the other electrode terminals of the other thin battery,
The other thin battery is juxtaposed on the side of the one thin battery so that the positive terminal of the one thin battery and the same polarity terminal of the other thin battery are in the same direction,
The one connecting means electrically connects the positive terminal of the one thin battery and the same polarity terminal of the other thin battery,
An assembled battery including at least two or more thin batteries in which the negative terminal of the one thin battery and the same-polarity terminal of the other thin battery are electrically connected by another connection means.

An assembled battery having a plurality of thin batteries, wherein the thin batteries according to claim 1 are electrically connected,
Laminating the other thin battery on the upper part in the vertical direction of the one thin battery so that the positive electrode terminal of the one thin battery and the same polarity terminal of the other thin battery are in the same direction,
Electrically connecting the positive terminal of the one thin battery and the positive terminal of the other thin battery;
An assembled battery including at least two or more thin batteries in which the negative terminal of the one thin battery and the negative terminal of the other thin battery are electrically connected.

A composite assembled battery having a plurality of assembled batteries in which the assembled battery according to claim 13 or 14 is electrically connected,
Each assembled battery has an assembled battery positive terminal and an assembled battery negative terminal electrically connected to the outside,
A composite including at least two or more of the assembled batteries in which one of the assembled battery positive electrode terminal or the assembled battery negative electrode terminal and the other assembled battery other electrode terminal of the other assembled battery are electrically connected. Assembled battery.

A composite assembled battery having a plurality of assembled batteries in which the assembled battery according to claim 13 or 14 is electrically connected,
Each assembled battery has an assembled battery positive terminal and an assembled battery negative terminal electrically connected to the outside,
A positive terminal for battery pack one of the assembled battery, a positive electrode terminal assembled battery of another of said battery pack and electrically connected,
A composite assembled battery including at least two or more assembled batteries in which the assembled battery negative electrode terminal of the one assembled battery and the assembled battery negative electrode terminal of the other assembled battery are electrically connected.

A vehicle on which the composite battery pack according to claim 15 or 16 is mounted.

By heat-sealing the synthetic resin layer of the outer circumferential edge portion of the two sheet-like sealing means having at least one or more synthetic resin layer, sealing the power generating element,
A method of manufacturing a thin battery in which a positive electrode terminal and a negative electrode terminal are led out from an outer peripheral edge,
The thermal fusion step of heat-sealing by thermal fusion region located at the outer peripheral edge portion of the sealing means possess at least 2 or more,
A method for manufacturing a thin battery in which the heat-sealed region in each heat-welding step is the same region .

19. The method for manufacturing a thin battery according to claim 18, wherein the last heat fusion step among the at least two heat fusion steps is a final step in the manufacturing process of the thin battery.

In the last heat fusion step of the at least two or more heat fusion steps, the thickness after the last heat fusion of the sealing means in the heat fusion region is a non-heat fusion region. The method for manufacturing a thin battery according to claim 18 or 19, wherein heat fusion is performed so that the thickness of the sealing means in the fusion region is 60 to 90%.

In the last heat fusion step of the at least two heat fusion steps, the thickness after the last heat fusion of the synthetic resin layer positioned in the heat fusion region is the non-heat fusion region. The method for producing a thin battery according to any one of claims 18 to 20, wherein heat fusion is performed so as to be 0.65 to 0.85 times the thickness of the synthetic resin layer positioned at a position.