JP4186260B2

JP4186260B2 - Thin battery

Info

Publication number: JP4186260B2
Application number: JP22627798A
Authority: JP
Inventors: 真志生渋谷; 尚富田
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1998-08-10
Filing date: 1998-08-10
Publication date: 2008-11-26
Anticipated expiration: 2018-08-10
Also published as: JP2000058014A

Description

【０００１】
【発明の属する技術分野】
本発明は、電極材と高分子電解質とを積層構成してなるリチウムイオン電池等の薄型電池に関し、詳細には電池構体の外装構造に関する。
【０００２】
【従来の技術】
電池は、化学エネルギーや物理的エネルギー或いは生物化学エネルギーを電気的エネルギーに変換する装置と定義され、化学電池、生物電池或いは物理電池等に大分類される。例えば化学電池については、化学変化の過程が可逆的でないもの或いは充電可能に構成されていない一次電池と、化学変化の過程が可逆的であるもの或いは充電可能に構成されている二次電池及び反応に関与する物質を外部から供給して反応生成物を外部に取り出しながら化学反応を促進する燃料電池等に分類される。
【０００３】
電池は、携帯型電子機器等の電源として汎用されている。かかる携帯型電子機器は、その多機能化に伴って電源容量の確保とともにより携帯性の確保が求められており、電源の小型化、軽量化とともに薄型化、換言すれば薄型電池の要求が高まっている。携帯型電子機器には、一般にエネルギー密度、出力密度の大きいリチウム電池が用いられている。従来のリチウム電池は、電極間の導電性物質として液体の電解液が用いられており、この電解液の液漏れを防ぐために金属缶が備えらる。従来のリチウム電池は、機械的強度を保持するために金属缶を４ｍｍ以下に構成することが困難であるために、薄型化について限界があった。
【０００４】
一方、最近の電池においては、無機或いは有機の非水固体電解質や高分子ゲルからなる非水半固体化電解質を用いた電池が提案されている。これら半固体化電解質を用いた電池は、流動性が無い或いは極めて小さい電解質の特性によってその厚みが一定に保持され、またこの電解質と電極間の接着力によって電極間の距離や圧力が一定に保持されることから金属缶が不要とされて、軽量化や小型化とともに薄型化が図られると期待されている。
【０００５】
例えば図６に示した薄型リチウムイオン電池１００は、帯状集電体上に正極活物質を被着するとともにゲル状電解質を塗布した正極材と、帯状集電体上に負極活物質を被着するとともにゲル状電解質を塗布した負極材とをセバレータを挟んで積層した後にこれを平たく折り畳んで電池構体１０１を構成している。薄型リチウムイオン電池１００は、この電池構体１０１の正極材と負極材とに導線を網目状に織ってなる正極端子１０２及び負極端子１０３とをそれぞれ接合する。
【０００６】
薄型リチウムイオン電池１００は、これら正極端子１０２及び負極端子１０３の先端部を外方に露呈した状態で、フィルム状のラミネート材１０４によって電池構体１０１を封装してなる。ラミネート材１０４は、内部に少なくとも一層以上のアルミニウム層を含む高分子多層フィルムからなり、電池構体１０１を包み込んだ状態で外周部に熱溶着処理が施されて熱用地着部位１０５が形成される。
【０００７】
なお、薄型電池としては、例えば上述したリチウム電池と基本的な構成を同様としたポリマー電池も注目されている。このポリマー電池は、帯状集電体上に正極活物質を被着してなる正極材と、帯状集電体上に負極活物質を被着してなる負極材との間にポリマー電解材からなるセバレータを挟み込んで電池構体が構成される。ポリマー電池も、電池構体をラミネート材により包み込んだ状態で、このラミネート材の周囲に熱溶着処理が施されてなる。
【０００８】
上述した高分子多層フィルムからなるラミネート材１０４は、高い気密性や軽量・薄厚にもかかわらず機械的強度が大きいといった特性を有するとともに、熱溶着等の極めて簡易な溶着処理を施すことによって電池構体１０１を高精度に密封することができる。したがって、従来の薄型リチウムイオン電池１００は、厚み寸法が４ｍｍ程度を限界としていた金属缶を有するリチウム電池と比較して、小型軽量化とともに１ｍｍ以下に構成することが可能とされしかも防湿性にも優れていることから、様々な携帯型電子機器等の電源として使用した場合にその小型化、軽量化とともに薄型化に貢献する。
【０００９】
【発明が解決しようとする課題】
ところで、従来の薄型リチウムイオン電池１００は、上述したように高分子多層フィルムからなるラミネート材１０４の外周部に電池構体１０１を密封するために熱溶着部位１０５が構成される。従来の薄型リチウムイオン電池１００は、用いられる非水電解質の特性から、電池構体１０１を密封する外装材について高い防湿性が要求される。ラミネート材１０４は、熱溶着部位１０５の幅寸法が大きい程その防湿性が高くなる。熱溶着部位１０５は、通常仕様の高分子多層フィルムを用いる場合に最低でも５ｍｍ以上に設定することが望ましい。
【００１０】
したがって、従来の薄型リチウムイオン電池１００は、上述したように全体が薄型に構成されるが、外周部にデッドスペースとしての熱溶着部位１０５が構成されるために、例えば一辺が数センチ以下の小型仕様とされる場合に体積エネルギー密度の効率が悪くなるといった問題があった。このため、従来の薄型リチウムイオン電池１００は、金属缶を有するリチウム電池と比較して、大幅な軽量化も図られるが、体積比では１／２乃至１／３程度にすぎない。
【００１１】
従来の薄型リチウムイオン電池１００においては、熱溶着部位１０５を内側へと折り曲げることによって外形寸法を小さくする対策を講じることも考慮されるが、この熱溶着部位１０５が硬いために作業が面倒となりかつきれいな状態で折り曲げることが困難である。また、従来の薄型リチウムイオン電池１００は、熱溶着部位１０５を折り曲げた場合にはその分厚み寸法も増加し、実質的な薄型化が達成されなくなるといった問題が生じる。さらに、従来の薄型リチウムイオン電池１００は、隣り合う二辺の熱溶着部位１０５が重なり合うためにさらに厚み寸法が増加してしまうといった問題もある。
【００１２】
したがって、本発明は、少なくとも正極材、負極材、高分子電解質とが積層構成されてなる薄型の電池構体を有し、体積エネルギー密度が向上されるとともに小型軽量化と長寿命化が図られた薄型電池を提供することを目的に提案されたものである。
【００１３】
【課題を解決するための手段】
この目的を達成する本発明にかかる薄型電池は、少なくとも正極材と負極材と高分子電解質とが積層構成されてなる電池構体と、電極端子部材と、金属箔からなる外装材とを備えてなる。薄型電池は、外装材によって、電極端子部材の先端部を露呈させた状態で電池構体を包み込むとともに、この外装材の外周部を接合してなり、外装材を電極端子部材の先端部を外方に露呈させた状態でさらに封装材によって被覆されることにより電池構体を密封してなる。
【００１４】
また、本発明にかかる薄型電池は、外装材が正極材又は負極材の集電体と電気的に接合されることによって電極端子を構成してなる。さらに、薄型電池は、電極端子部材に絶縁樹脂シートをあてがって外方へと引き出した状態で、外装材がその外周部を接合されることによって電池構体を密封する。さらにまた、薄型電池は、外装材によって密封された電池構体を、電極端子部材の先端部を外方に引き出した状態でさらに封装材によって封装されてなる。
【００１５】
以上のように構成された本発明にかかる薄型電池によれば、外装材が金属箔であることからその接合部位の折曲げ処理が容易であり、電池構体を密封した状態で極めて簡単に内側に折り曲げることが可能であるとともに全体の厚みを大幅に増加させることも無い。したがって、薄型電池は、より薄型かつ小型、軽量であって体積エネルギー密度の向上が図られるとともに防湿性に優れることで長寿命化が図られる。
【００１６】
また、本発明にかかる薄型電池によれば、外装材が正極電極端子部材又は負極電極端子部材のいずれか一方の電極端子部材として作用することから、構造の簡易化が図られる。薄型電池によれば、外装材を接合する際に絶縁樹脂シートを介して電極端子部材が絶縁を保持されて引き出されることから、その処理が簡易に行われるとともに引出し部における密封性も保持される。薄型電池によれば、外装材をさらに封装材によって被覆して補強されることから、機械的強度の向上が図られる。
【００１７】
【発明の実施の形態】
以下、本発明の実施の形態について図面を参照して詳細に説明する。本発明の実施の形態として図面に示した薄型電池１は、負極端子部材３が設けられた電池構体２を、図１に示すように負極端子部材３の先端部３ａが露呈するようにして外装材４によって密封してなる薄型のリチウムイオン二次電池を示す。リチウムイオン二次電池１は、詳細を後述するが外装材４が正極端子部材に兼用される。
【００１８】
リチウムイオン二次電池１は、図２に示すように、電池構体２が、正極材５と、負極材６と、これら正極材５と負極材６とによって挟み込まれたセパレータ７と、ゲル状電解質８（８ａ、８ｂ）との積層体によって構成される。リチウムイオン二次電池１は、詳細を後述するが、図３に示すように負極端子部材３を絶縁シート９（９ａ、９ｂ）によって挟み込むことにより外装材４に対して絶縁性を保持した状態でこの外装材４から引き出してなる。
【００１９】
電池構体２は、詳細を後述するように、正極材５、負極材６、セパレータ７及びゲル状電解質８からなる積層体を、正極材５が最外層を構成するようにして折り畳まれてなる。電池構体２は、積層体を折り畳んだ状態で厚み寸法が約３．５ｍｍとされる。なお、電池構体２は、正極材５、負極材６、セパレータ７及びゲル状電解質８の積層体を平たく折り畳んで構成するばかりでなく、例えばつづら折りしたり巻回して構成してもよい。
【００２０】
セパレータ７には、厚みが２５μｍの多孔質ポリプロピレンフィルムが用いられる。このセパレータ７は、特に用いなくともよいが、後述するように外装材４を電極端子に兼用する場合において適宜の形状とすることで正極材５或いは負極材６と外装材４との絶縁を保持する部材としても有効に機能する。
【００２１】
正極材５は、アルミニウム箔からなる正極集電体１０に正極活物質１１（１１ａ、１１ｂ）を塗布してなる。正極活物質１１は、ニッケル酸リチウム（ＬｉＮｉＯ₂）９０重量％、粉末ポリフッ化ビニリデン３重量％、粉末黒鉛７重量％を、Ｎメチルピロリドン（ＮＭＰ）を溶媒として分散させてなる。正極材５は、帯状の正極集電体１０の両面にそれぞれ正極活物質１１を塗布した後、１００°Ｃの環境で２４時間の減圧乾燥処理を施し、さらに適宜の加圧力のロールプレスにより圧縮処理を施して製作される。正極材５は、これを約８００ｍｍ×１２０ｍｍの外形寸法を以って切り出して使用される。勿論、正極材５は、かかる構成に限定されるものでは無い。
【００２２】
負極材６は、銅箔からなる負極集電体１２に負極活物質１３を片面に塗布してなる。負極活物質１３は、人造黒鉛９１重量％、粉状ポリフッ化ビニリデン９重量％を、Ｎメチルピロリドン（ＮＭＰ）を溶媒として分散させてなる。負極材６は、帯状の負極集電体１２に負極活物質１３を塗布した後、１２０°Ｃの環境で２４時間の減圧乾燥処理を施し、さらに適宜の加圧力のロールプレスにより圧縮処理を施して製作される。負極材６は、これを正極材５と同様に、約８００ｍｍ×１２０ｍｍの外形寸法を以って切り出して使用される。勿論、負極材６は、かかる構成に限定されるものでは無い。
【００２３】
ゲル状電解質８には、ポリアクリロニトリル（ＰＡＮ）、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、六フッ化燐酸リチウム（ＬｉＰＦ₆）からなるポリアクリロニトリル系ゲル電解質が用いられる。ゲル状電解質８は、上述した構成物が仕込みのモル組成比をＰＡＮ：ＥＣ：ＰＣ：ＬｉＰＦ₆＝１２：５３：２７：８となるように調整されてなる。ゲル状電解質８は、所定量のＥＣとＰＣとを混合して１５０°Ｃに加熱した後、ＰＡＮを所定量混合して撹拌することによりこのＰＡＮが溶解して粘性を有する溶液となり、これに所定量のＬｉＰＦ₆を添加して溶解させる手順を経てゲル状に作成されてなる。
【００２４】
上述した正極材５と負極材６とは、ゲル状電解質８を塗布した主面を互いに対向させ、セバレータ７を挟み込んで積層される。正極材５と負極材６とは、ゲル状電解質８の接着作用によって、その距離や圧力が一定に保持された状態で積層されて電池構体２を構成する。なお、セバレータ７は、後述するように外装材４によって電池構体２を包み込んだ際にこの外装材４と負極材６とが接触しないようにするために、その幅寸法が正極材５や負極材６の幅寸法よりもやや大とされている。電池構体２は、正極材５、負極材６及びセバレータ７の積層体を折り畳んで、外形寸法が全体で約８０ｍｍ×１３０ｍｍ×３．５ｍｍを以って構成される。
【００２５】
負極端子部材３は、例えば直径が５０μｍの銅線が用いられ、これを７５μｍの間隔で網目状に織ったものを矩形に切断したものが用いられる。負極端子部材３は、その基端部３ｂが負極集電体１２にスポット溶接等によって接合される。負極端子部材３は、引張り強度を保持するために、各網目が長手方向に対して長軸となるいわゆる縦目で構成したものを用いることが好ましい。負極端子部材３は、図３に示すように電池構体２の長手方向の一端側を端子引出し部２ａとして、その先端部３ａが突出される。
【００２６】
外装材４には、薄厚で軽量であるとともに機械的強度や防湿性に優れ、嵩張らずに折り畳むことが可能な金属箔、具体的には厚み寸法が約４０μｍのアルミニウム箔が用いられる。外装材４は、外形寸法が少なくとも上述した電池構体２の外形寸法よりもやや大きいものが用いられる。外装材４は、図３に示すように折り目部位４ａを電池構体２の端子引出し部２ａと反対側の部位２ｂに位置させて長さ方向の中央部から２つ折りにされる。外装材４は、相対する先端部４ｂ、４ｃが端子引出し部２ａ側において重ね合わされる。外装材４は、折り目部位４ａと直交する両側面に沿って超音波溶接処理が施されることによって両側面接合部位４ｄ、４ｅを形成して袋状に構成される。
【００２７】
外装材４には、電池構体２の最外周層を構成する集電体と同一の材料の金属箔を用いることが好ましい。電池構体２は、上述したように最外周層を正極集電体１０によって構成したことから、外装材４にアルミニウム箔が用いられている。アルミニウム箔は、軽量であるとともに廉価であることから好適である。勿論、外装材４としては、アルミニウムを主成分としたものであれば良く、アルミニウム合金箔や表面に蒸着等によってアルミニウム層が形成された金属箔を用いてもよい。外装材４には、上述したように厚み寸法が４０μｍのアルミニウム箔を用いたが、材料強度と質量、水分透過性によって適宜選択され、１０μｍ乃至１００μｍの厚み寸法のものが用いられる。外装材４は、ピンホールフリーや加工性、外装としての厚みや重量を考慮すると、２０μｍ乃至６０μｍの厚み寸法が好適である。
【００２８】
外装材４には、先端部４ｂ、４ｃの相対する内面に、絶縁樹脂シート９があてがわれる。絶縁樹脂シート９は、外装材４の幅寸法とほぼ等しい長さのポリエチレンフィルムからなり、図３に示すように外装材４の先端部４ｂ、４ｃに沿って負極端子部材３と直交してあてがわれる。絶縁樹脂シート９は、外装材４がその重ね合わされた先端部４ｂ、４ｃに真空加熱溶着処理が施されて先端接合部位４ｆを形成することによって、この外装材４と負極端子部材３との絶縁を保持するとともに先端部４ｂ、４ｃを密封する。
【００２９】
なお、絶縁樹脂シート９には、外装材４の幅寸法とほぼ等しい長さを有するものを用いて先端接合部４ｆに段差が生じないように構成したが、少なくとも負極端子部材３を被覆するに足る長さを有していればよいことは勿論である。絶縁樹脂シート９には、ポリエチレンフィルム以外にも、金属との接合性が良好であるとともに水分透過性が小さい特性を有する例えばポリオレフィン、ナイロン、アイオノマー、ポリエチレンテレフタレート等のフィルム材を用いてもよい。
【００３０】
上述したリチウムイオン二次電池１においては、外装材４が正極集電体１０と接合されて正極端子を構成し、基端部３ｂを負極集電体１３に接合した負極端子部材３を設けたが、かかる構成に限定されないことは勿論である。リチウムイオン二次電池１は、正極集電体１０と負極集電体１３とにそれぞれ接合される一対の電極端子部材を設けてもよい。
【００３１】
また、リチウムイオン二次電池１は、外装材４を負極端子として構成し、正極集電体１０と接合された正極端子部材を設けるようにしてもよい。この場合、リチウムイオン二次電池１は、電池構体２の最外周層が負極集電体１３となるように折り畳まれてることによってこの負極集電体１３と外装材４とが電気的に接続されるようにする。正極端子部材は、外装材４に対して絶縁性を保持されてその先端部が外部へと突出露呈される。
【００３２】
外装材４には、電池構体２の最外周層を負極集電体１３として外装材４を負極端子として兼用した場合には、銅箔を用いることが好適である。勿論、外装材４には、ニッケル、鉄、ステンレス、アルミニウム或いはこれら金属のいずれか一種類以上からなる金属箔、若しくはこれら金属を含む合金箔やこれら金属を表面にメッキや蒸着等することによって形成した金属箔を用いてもよい。
【００３３】
リチウムイオン二次電池１は、上述した各構成部材により、以下の方法で製作される。すなわち、リチウムイオン二次電池１は、電池構体２が、負極端子部材３の先端部３ａを突出露呈させて外装材４によって密封されてなる。リチウムイオン二次電池１は、図３に示すように、２つ折りされた外装材４がその先端部４ｂ、４ｃを負極端子部材３が引き出される引出し部２ａ側で重ね合わされて電池構体２を包み込んでなる。リチウムイオン二次電池１は、外装材４に、負極端子部材３を挟んでその先端部４ｂ、４ｃの内面に絶縁樹脂シート９があてがわれてなる。
【００３４】
リチウムイオン二次電池１は、外装材４が、電極構体２と重ならないように、折り目部位４ａと直交する両側面の全域に亘って超音波溶接処理が施されることによって両側に沿ってた側面接合部位４ｄ、４ｅがそれぞれ形成されて袋状に接合されてなる。リチウムイオン二次電池１は、これら側面接合部位４ｄ、４ｅが、負極端子部材３を引き出す部位ではなく、溶融されたアルミニウムが再固化することにより接合されることで極めて良好な防水特性を以って強固に接合されてなる。
【００３５】
リチウムイオン二次電池１は、側面接合部位４ｄ、４ｅについて、従来のラミネート材と比べて大きな接合幅を必要としないが、同等の５ｍｍ幅で形成されてもよい。リチウムイオン二次電池１は、側面接合部位４ｄ、４ｅが、外装材４にアルミニウム箔を用いたことにより比較的簡単に内側に折り曲げることが可能とされる。したがって、リチウムイオン二次電池１は、側面接合部位４ｄ、４ｅを折り曲げられた場合においてもその厚みが極めて小さいために、その厚み寸法が電池構体２の厚みと寸法とほとんど変わらなず、有効な体積率となる。
【００３６】
リチウムイオン二次電池１は、外装材４が、重ね合わせた先端部４ｂ、４ｃに真空加熱溶着処理が施こされて内部を真空にする先端接合部４ｆが形成されてなる。リチウムイオン二次電池１は、負極端子部材３が、その網目内に溶融した絶縁樹脂シート９が溶け込むことによって外装材４との絶縁が確実に保持された状態で先端接合部４ｆにしっかりと接合されなる。リチウムイオン二次電池１は、負極端子部材３を引き出すために外装材４の先端接合部４ｆが側面接合部位４ｄ、４ｅに対してその防水特性をやや劣化した状態となる。したがって、リチウムイオン二次電池１においては、負極端子部材３を部分的に絶縁する絶縁樹脂シート９を用いる場合に、この絶縁樹脂シート９が負極端子部材３の幅寸法に対して１ｍｍ程度大きい長さのものを用いることが好ましい。
【００３７】
リチウムイオン二次電池１は、上述したように外装材４の先端接合部４ｆに、幅方向の全域に亘る長さ寸法を有する絶縁樹脂シート９を用いることで段差が無くかつ良好な防水特性を以って構成される。リチウムイオン二次電池１は、先端接合部４ｆを、側面接合部位４ｄ、４ｅと同様に超音波溶接によって形成してもよい。リチウムイオン二次電池１は、外装材４の内部を真空にして電池構体２を密封することで、外装材４がこの電池構体２に密着した状態となる。リチウムイオン二次電池１は、電池構体２の最外周層が正極集電体１０によって構成されることから、外装材４とこの正極集電体１０との電気的導通が確実に保持される。リチウムイオン二次電池１は、かかる構成によって外装材４が正極端子としても安定して作用する。
【００３８】
本発明は、上述したリチウムイオン二次電池１に限定されるものでは無く、例えば正極集電体にリチウムイオンを吸収できる正極活物質を塗布してなる正極材と、金属リチウムからなる負極材と、高分子電解質とを備えるリチウム一次電池にも適用可能であることは勿論である。また、本発明は、種々の電池にも適用可能であり、例えば液体電解質を用いた電池であってもよい。さらに、本発明は、正極材と負極材との間にポリマー電解質を挟み込んだいわゆるポリマー電池にも好適に実施される。
【００３９】
図４に示した薄型電池２０は、上述したリチウムイオン二次電池１に対してさらに機械的強度の向上を図ったものである。薄型電池２０は、リチウムイオン二次電池１の外装材４を、樹脂フィルム２１によって封装してなる。樹脂フィルム２１は、例えばポリオレフィンやテフロン系の熱収縮性を有する樹脂によって一方を開口２２とした袋状に成形されてなる。樹脂フィルム２１は、リチウムイオン二次電池１の外形寸法よりもやや大きめの内部空間を有してなる。
【００４０】
薄型電池２０は、リチウムイオン二次電池１が、同図に示すように正極端子部材３が露呈された部位と反対側を装填側として、開口２２から樹脂フィルムからなる封装材２１の内部に装填される。薄型電池２０は、開口２２から負極端子部材３の先端部３ａを露呈させた状態で、封装材２１に加熱処理を施す。薄型電池２０は、これによって封装材２１がリチウムイオン二次電池１の外形に倣って収縮してこれを封装する。
【００４１】
薄型電池２０は、熱収縮性樹脂フィルムからなる封装材２１によって全周を覆われることから、機械的強度の向上が図られる。薄型電池２０は、封装材２１が加熱処理を施されて収縮することで装填したリチウムイオン二次電池１の外周部に密着することから、外形寸法がこのリチウムイオン二次電池１とほとんど同等に構成される。
【００４２】
なお、封装材２１については、無駄な体積が生じないようにリチウムイオン二次電池１の装填操作に支障の無い範囲でその大きさに近い範囲で成形することが好ましい。また、封装材２１は、リチウムイオン二次電池１の形状に併せて、円筒形や平たい筒状或いは封筒状等の適宜の形状に成形される。
【００４３】
図５に示した薄型電池３０は、上述したリチウムイオン二次電池１について、外装材４の両側面に形成された側面接合部位４ｄ、４ｅを内側に折り曲げるとともにこれを封装体２５によって封装した構成に特徴を有している。側面接合部位４ｄ、４ｅは、上述したようにアルミニウム箔からなる外装体４に超音波溶接を施して形成される。側面接合部位４ｄ、４ｅは、外装体４の材料特性から折り曲げが極めて簡単であるとともにその厚みも小さい。
【００４４】
薄型電池３０は、リチウムイオン二次電池１が、同図に示すように負極端子部材３が露呈された部位と反対側を装填側として、開口２６から封装体２５の内部に装填される。薄型電池３０は、封装体２５によって折り曲げられた側面接合部位４ｄ、４ｅが保持される。封装体２５は、側面接合部位４ｄ、４ｅの保持作用とともに装填されたリチウムイオン二次電池１の保護作用も奏する。
【００４５】
なお、封装体２５については、上述した熱収縮性樹脂フィルムと同様に構成されてもよい。また、封装体２５は、熱可塑性樹脂や熱・光硬化性樹脂によって側面接合部位４ｄ、４ｅが予め折り曲げられたリチウムイオン二次電池１の外周部をモールドした部材であってもよい。
【００４６】
上述したリチウムイオン二次電池１を基本として以下に示す第１の実施例薄型電池１Ａ乃至第６の実施例薄型電池１Ｆと、外装材にラミネート材を用いた第１の比較例薄型電池１００Ａ乃至第３の比較例薄型電池１００Ｃとを製作して、それぞれの評価を行った。
【００４７】
第１の実施例薄型電池１Ａは、上述した実施の形態に示したリチウムイオン二次電池１によって製作した。電池構体２Ａは、正極材５、負極材６及びセバレータ７からなる積層体を平たく折り畳むようにして巻回し、最外周層を正極集電体１０として外装材４を正極端子として構成した。電極端子部材３は、直径５０μｍの銅線を７５μｍ間隔の網目で編んだ金属網を裁断し、その基端部３ｂを負極集電体１２に接続した。外装材４には、厚みが４０μｍのアルミニウム箔が用いられ、超音波溶接を施して５ｍｍ幅の側面接合部位４ｄ、４ｅを形成した。
【００４８】
第２の実施例薄型電池１Ｂは、電池構体２Ｂが正極材５、負極材６及びセバレータ７からなる積層体をつづら折りしてなり、最外周層を負極集電体１２として外装材４を負極端子として構成したリチウムイオン二次電池である。電極端子部材３は、直径５０μｍのアルミニウム線を７５μｍ間隔の網目で編んだ金属網を裁断し、その基端部３ｂを正極集電体１０に接続した。外装材４には、厚みが４０μｍのニッケル箔を用い、超音波溶接を施して５ｍｍ幅の側面接合部位４ｄ、４ｅを形成した。
【００４９】
第３の実施例薄型電池１Ｃは、正極材５にニッケル酸リチウム（ＬｉＮｉＯ₂）が用いられるとともに負極材６に難黒鉛化炭素が用いられ、上述した第１の実施例薄型電池１Ａと同様の工程によって作成したリチウムイオン二次電池である。外装材４には、厚みが４０μｍのアルミニウム箔が用いられ、超音波溶接を施して５ｍｍ幅の側面接合部位４ｄ、４ｅを形成した。
【００５０】
第４の実施例薄型電池１Ｄは、正極材５にニッケル酸リチウム（ＬｉＮｉＯ₂）が用いられるとともに負極材６に厚みが３００μｍのリチウム金属が用いられ、上述した第１の実施例薄型電池１Ａと同様の工程によって作成したリチウム金属二次電池である。電極端子部材３は、その基端部３ｂを負極材６のリチウム金属に圧着して接続した。外装材４には、厚みが４０μｍのアルミニウム箔が用いられ、超音波溶接を施して５ｍｍ幅の側面接合部位４ｄ、４ｅを形成した。
【００５１】
第５の実施例薄型電池１Ｅは、正極材５に二酸化マンガン、負極材６に金属リチウムが用いられ、上述した第１の実施例薄型電池１Ａと同様の工程によって作成したリチウム一次電池である。外装材４には、厚みが４０μｍのアルミニウム箔が用いられ、超音波溶接を施して５ｍｍ幅の側面接合部位４ｄ、４ｅを形成した。
【００５２】
第６の実施例薄型電池１Ｆは、上述した第２の実施の形態として示したリチウムイオン二次電池２０と同様であり、第１の実施例リチウムイオン二次電池１Ａを製作した後にその側面接合部位４ｄ、４ｅを内側に折り曲げるとともにこれを熱収縮チューブからなる封装体２５によって封装したリチウムイオン二次電池である。
【００５３】
第１の比較例薄型電池１００Ａは、上述した第１の実施例リチウムイオン二次電池１Ａと同様の工程によって電池構体１０１を製作した後に、この電池構体１０１を密封する外装体として従来のラミネートフィルム１０４を用いたリチウムイオン二次電池である。ラミネートフィルム１０４は、外層が厚み寸法５０μｍのポリエチレンテレフタレートフィルム、中層が厚み寸法２０μｍのアルミニウム箔、内層が厚み寸法１５０μｍのポリエチレンフィルムからなる。第１の比較例薄型電池１００Ａは、このラミネートフィルム１０４によって、第１の実施例リチウムイオン二次電池１Ａの外装材４と同様の方法により電池構体１０１を包み込んだ後に、両側面に沿ってインパルスシーラによる加熱溶融処理を施して幅１０ｍｍの熱溶着部位１０５を形成してなる。
【００５４】
第２の比較例薄型電池１００Ｂは、上述した第４の実施例薄型電池１Ｄと同様の工程によって電池構体１０１を製作した後に、この電池構体１０１を密封する外装体として従来のラミネートフィルム１０４を用いたリチウム金属二次電池である。第２の比較例薄型電池１００Ｂも、第１の比較例薄型電池１００Ａと同様にラミネートフィルム１０４によって電池構体１０１を包み込んだ後に、両側面に沿ってインパルスシーラによる加熱溶融処理を施して幅１０ｍｍの熱溶着部位１０５を形成してなる。
【００５５】
第３の比較例薄型電池１００Ｃは、上述した第５の実施例薄型電池１Ｅと同様の工程によって電池構体１０１を製作した後に、この電池構体１０１を密封する外装体として従来のラミネートフィルム１０４を用いたリチウム一次次電池である。第３の比較例薄型電池１００Ｃも、第１の比較例薄型電池１００Ａと同様にラミネートフィルム１０４によって電池構体１０１を包み込んだ後に、両側面に沿ってインパルスシーラによる加熱溶融処理を施して幅１０ｍｍの熱溶着部位１０５を形成してなる。
【００５６】
上述した各実施例薄型電池１Ａ乃至１Ｆと比較例薄型電池１００Ａ乃至１００Ｃとについて、それぞれの側面接合部位４ｄ、４ｅ及び熱溶着部位１０５を内側に折り曲げた状態での厚み寸法を実測した結果は次の表１のとおりであった。なお、各二次電池については、満充電時における厚み寸法を実測した。
【００５７】
【表１】

【００５８】
各実施例薄型電池１Ａ乃至第６の実施例薄型電池１Ｆは、表１から明らかなように、第１の比較例薄型電池１００Ａ乃至第３の比較例薄型電池１００Ｃと比較してその厚み寸法が１５％程度まで薄厚に構成される。
【００５９】
次に、第１の実施例薄型電池１Ａ乃至第６の実施例薄型電池１Ｆと第１の比較例薄型電池１００Ａ乃至第３の比較例薄型電池１００Ｃとについて、次の評価試験を行った。
【００６０】
各実施例二次電池（１Ａ乃至１Ｄ及び１Ｆ）と比較例二次電池（１００Ａ、１００Ｂ）との評価方法は、温度６０°Ｃ、湿度６０％の環境条件下で、０．５Ｃの充放電サイクル試験を約７０日間かけて３００サイクル行い、その初回電池容量からの容量維持率を測定して評価した。さらに、この充放電サイクル試験試験の終了後に、各二次電池について、内部の電解質を分析して侵入した水分量を測定して評価した。なお、０．５Ｃとは、電池の定格容量を２時間で放電させる電流値である。
【００６１】
実施例二次電池（１Ａ乃至１Ｄ及び１Ｆ）と比較例二次電池（１００Ａ、１００Ｂ）のサイクル試験結果は、次の表２のとおりであった。
【００６２】
【表２】

【００６３】
また、実施例一次電池１Ｅと比較例一次電池１００Ｃとの評価方法は、温度６０°Ｃ、湿度６０％の高温多湿の環境条件下で７０日間放置した場合と、常温常湿の環境条件下で７０日間放置した場合とでの放電容量を測定して評価した。さらに、この放置試験の終了後に、各一次電池について、内部の電解質を分析して侵入した水分量を測定して評価した。
【００６４】
実施例一次電池１Ｅと比較例一次電池１００Ｃの放置試験結果は、次の表３のとおりであった。
【００６５】
【表３】

【００６６】
各実施例薄型電池１Ａ乃至第６の実施例薄型電池１Ｆは、表２及び表３から明らかなように、第１の比較例薄型電池１００Ａ乃至第３の比較例薄型電池１００Ｃと比較して防湿特性に優れている。したがって、各実施例薄型電池１Ａ乃至第６の実施例薄型電池１Ｆは、第１の比較例薄型電池１００Ａ乃至第３の比較例薄型電池１００Ｃと比較して電池寿命が長く、より薄型であって体積エネルギー密度が高く構成される。
【００６７】
【発明の効果】
以上詳細に説明したように、本発明にかかる薄型電池によれば、薄型に構成された電池構体を金属箔からなる外装材によって密封したことにより、より薄型でかつ小型、軽量であって体積エネルギー密度が高く、また防湿性に優れることで電池寿命も長く極めて高性能である。さらに、封装材によって被覆されることから、機械的強度の向上を図ることができる。したがって、薄型電池は、携帯型電子機器等の電源として好適に用いられ、その小型、軽量化と多機能化を実現する。
【図面の簡単な説明】
【図１】本発明にかかる薄型電池の実施の形態として示すリチウム金属二次電池の構成を説明する斜視図である。
【図２】同リチウム金属二次電池に備えられる電池構体の構成を説明する要部縦断面図である。
【図３】同リチウム金属二次電池における外装材による電池構体の密封操作の説明図である。
【図４】本発明にかかる他の薄型電池の実施の形態を示し、電池構体の密封操作の説明図である。
【図５】本発明にかかる他の薄型電池の実施の形態を示し、封装材による封装操作の説明図である。
【図６】従来のリチウム金属二次電池の斜視図である。
【符号の説明】
１リチウム金属二次電池（薄型電池）、２電池構体、２ａ端子引出し部、３負極端子部材（電極端子部材）、４外装体、４ａ折り目部位、４ｄ,４ｅ側面接合部位、４ｆ先端接合部位、５正極材、６負極材、７セバレータ、８ゲル状電解質（高分子電解質）、９絶縁シート、１０正極集電体、１１正極活物質、１２負極集電体、１３負極活物質
封口材、６封口材、７ラミネート材、８正極端子部材、９負極端子部材、１０導線[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thin battery such as a lithium ion battery formed by laminating an electrode material and a polymer electrolyte, and more particularly to an exterior structure of a battery assembly.
[0002]
[Prior art]
Batteries are defined as devices that convert chemical energy, physical energy, or biochemical energy into electrical energy, and are broadly classified as chemical batteries, biological batteries, physical batteries, or the like. For example, for a chemical battery, a primary battery in which the process of chemical change is not reversible or not configured to be rechargeable, and a secondary battery and a reaction in which the process of chemical change is reversible or configured to be rechargeable It is classified as a fuel cell or the like that promotes a chemical reaction while supplying a substance involved in the reaction from outside and taking out a reaction product to the outside.
[0003]
Batteries are widely used as power sources for portable electronic devices and the like. Such portable electronic devices are required to have more power and more portable due to their multi-functionality, and the demand for thin batteries, in other words, the demand for thin batteries increases as the power source becomes smaller and lighter. ing. For portable electronic devices, lithium batteries having high energy density and high output density are generally used. A conventional lithium battery uses a liquid electrolyte as a conductive substance between electrodes, and a metal can is provided to prevent leakage of the electrolyte. The conventional lithium battery has a limit in reducing the thickness because it is difficult to make the metal can 4 mm or less in order to maintain the mechanical strength.
[0004]
On the other hand, in recent batteries, a battery using a non-aqueous semi-solid electrolyte made of an inorganic or organic non-aqueous solid electrolyte or a polymer gel has been proposed. Batteries using these semi-solid electrolytes have a constant thickness due to their non-fluid or extremely small electrolyte characteristics, and the distance and pressure between the electrodes are kept constant by the adhesive force between the electrolyte and the electrodes. Therefore, it is expected that a metal can is unnecessary, and that the thickness can be reduced as well as the weight and size are reduced.
[0005]
For example, in the thin lithium ion battery 100 shown in FIG. 6, a positive electrode active material is deposited on a strip-shaped current collector, and a positive electrode material coated with a gel electrolyte and a negative electrode active material is deposited on the strip-shaped current collector. At the same time, a negative electrode material coated with a gel electrolyte is laminated with a separator in between, and then folded flat to constitute the battery assembly 101. In the thin lithium ion battery 100, a positive electrode terminal 102 and a negative electrode terminal 103 made by weaving conductive wires in a mesh shape are joined to the positive electrode material and the negative electrode material of the battery assembly 101, respectively.
[0006]
The thin lithium ion battery 100 is formed by sealing the battery assembly 101 with a film-like laminate material 104 with the tip portions of the positive electrode terminal 102 and the negative electrode terminal 103 exposed to the outside. The laminate material 104 is made of a polymer multilayer film including at least one aluminum layer inside, and a thermal welding process is performed on the outer periphery of the battery assembly 101 in a state where the battery assembly 101 is wrapped, thereby forming a thermal landing portion 105.
[0007]
Note that, as a thin battery, for example, a polymer battery having the same basic configuration as the above-described lithium battery is also attracting attention. This polymer battery is composed of a polymer electrolyte material between a positive electrode material obtained by depositing a positive electrode active material on a strip-shaped current collector and a negative electrode material formed by depositing a negative electrode active material on a strip-shaped current collector. A battery assembly is formed by sandwiching the separator. The polymer battery is also formed by heat-sealing the periphery of the laminate material in a state where the battery structure is wrapped with the laminate material.
[0008]
The laminate material 104 made of the polymer multilayer film described above has characteristics such as high airtightness, high mechanical strength despite being lightweight and thin, and is subjected to an extremely simple welding process such as thermal welding to thereby form a battery structure. 101 can be sealed with high accuracy. Therefore, the conventional thin lithium ion battery 100 can be configured to be 1 mm or less with a reduction in size and weight as compared with a lithium battery having a metal can whose thickness dimension is limited to about 4 mm, and also has moisture resistance. Because of its superiority, when used as a power source for various portable electronic devices, etc., it contributes to reducing the size and weight as well as reducing the thickness.
[0009]
[Problems to be solved by the invention]
By the way, in the conventional thin lithium ion battery 100, as described above, the heat-welded portion 105 is configured to seal the battery assembly 101 on the outer peripheral portion of the laminate material 104 made of the polymer multilayer film. The conventional thin lithium ion battery 100 is required to have high moisture resistance for the exterior material for sealing the battery assembly 101 due to the characteristics of the nonaqueous electrolyte used. The laminate material 104 has a higher moisture resistance as the width dimension of the heat welding portion 105 is larger. It is desirable that the heat-welded portion 105 is set to at least 5 mm or more when a polymer multilayer film having a normal specification is used.
[0010]
Therefore, the conventional thin lithium-ion battery 100 is thin as a whole as described above, but since the thermal welding portion 105 as a dead space is formed in the outer peripheral portion, for example, a small size with a side of several centimeters or less. There was a problem that the efficiency of volumetric energy density deteriorated when the specification was adopted. For this reason, the conventional thin lithium ion battery 100 can be significantly reduced in weight as compared with a lithium battery having a metal can, but the volume ratio is only about 1/2 to 1/3.
[0011]
In the conventional thin lithium-ion battery 100, it may be considered to take measures to reduce the outer dimension by bending the heat welding portion 105 inward, but the work is troublesome because the heat welding portion 105 is hard. It is difficult to bend in a clean state. Further, the conventional thin lithium ion battery 100 has a problem that when the heat-welded portion 105 is bent, the thickness dimension increases accordingly, and the substantial thinning cannot be achieved. Further, the conventional thin lithium ion battery 100 has a problem that the thickness dimension is further increased because the two adjacent thermal welding portions 105 overlap each other.
[0012]
Therefore, the present invention has a thin battery structure in which at least a positive electrode material, a negative electrode material, and a polymer electrolyte are laminated, and the volume energy density is improved and the size and weight are reduced and the life is extended. It has been proposed for the purpose of providing a thin battery.
[0013]
[Means for Solving the Problems]
A thin battery according to the present invention that achieves this object comprises at least a battery structure in which a positive electrode material, a negative electrode material, and a polymer electrolyte are laminated, an electrode terminal member, and an exterior material made of a metal foil. . A thin battery encases the battery assembly with an exterior material with the tip of the electrode terminal member exposed, and joins the outer periphery of the exterior material. The battery assembly is hermetically sealed by being covered with a sealing material in a state where the outer end of the electrode terminal member is exposed to the outside. .
[0014]
Moreover, the thin battery concerning this invention comprises an electrode terminal, when an exterior material is electrically joined with the collector of a positive electrode material or a negative electrode material. Further, the thin battery seals the battery assembly by bonding the outer peripheral portion of the exterior member with the insulating resin sheet applied to the electrode terminal member and pulled outward. Further, the thin battery is formed by sealing a battery structure sealed with an exterior material with a sealing material in a state where the tip end portion of the electrode terminal member is drawn outward.
[0015]
According to the thin battery according to the present invention configured as described above, since the exterior material is a metal foil, it is easy to bend the joint portion, and the battery assembly is sealed in a very simple manner. It can be folded and does not significantly increase the overall thickness. Therefore, the thin battery is thinner, smaller and lighter, has an improved volume energy density, and is excellent in moisture resistance, thereby extending its life.
[0016]
In addition, according to the thin battery according to the present invention, the exterior material acts as either one of the positive electrode terminal member or the negative electrode terminal member, so that the structure can be simplified. According to the thin battery, since the electrode terminal member is pulled out while being insulated through the insulating resin sheet when the exterior material is joined, the processing is easily performed and the sealing performance at the drawer portion is also maintained. . According to the thin battery, since the exterior material is further covered with the sealing material and reinforced, the mechanical strength can be improved.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. A thin battery 1 shown in the drawings as an embodiment of the present invention has a battery assembly 2 provided with a negative electrode terminal member 3 with an exterior such that the tip 3a of the negative electrode terminal member 3 is exposed as shown in FIG. 2 shows a thin lithium ion secondary battery sealed with a material 4. Although the details of the lithium ion secondary battery 1 will be described later, the exterior material 4 is also used as the positive electrode terminal member.
[0018]
As shown in FIG. 2, the lithium ion secondary battery 1 includes a battery assembly 2 having a positive electrode material 5, a negative electrode material 6, a separator 7 sandwiched between the positive electrode material 5 and the negative electrode material 6, and a gel electrolyte. 8 (8a, 8b). The lithium ion secondary battery 1 will be described in detail later. In the state in which the negative electrode terminal member 3 is sandwiched between the insulating sheets 9 (9a, 9b) as shown in FIG. It is pulled out from the exterior material 4.
[0019]
As will be described in detail later, the battery assembly 2 is formed by folding a laminate composed of a positive electrode material 5, a negative electrode material 6, a separator 7, and a gel electrolyte 8 so that the positive electrode material 5 constitutes the outermost layer. The battery assembly 2 has a thickness dimension of about 3.5 mm in a state where the stacked body is folded. The battery assembly 2 may be configured not only by flatly folding the laminate of the positive electrode material 5, the negative electrode material 6, the separator 7, and the gel electrolyte 8, but may be configured by, for example, zigzag folding or winding.
[0020]
For the separator 7, a porous polypropylene film having a thickness of 25 μm is used. The separator 7 is not particularly required. However, the insulation between the positive electrode material 5 or the negative electrode material 6 and the outer packaging material 4 is maintained by using an appropriate shape when the outer packaging material 4 is also used as an electrode terminal as described later. It functions effectively also as a member to do.
[0021]
The positive electrode material 5 is formed by applying a positive electrode active material 11 (11a, 11b) to a positive electrode current collector 10 made of an aluminum foil. The positive electrode active material 11 is made of lithium nickelate (LiNiO ₂ ) 90% by weight, 3% by weight of powdered polyvinylidene fluoride and 7% by weight of powdered graphite are dispersed using N-methylpyrrolidone (NMP) as a solvent. The positive electrode material 5 is formed by applying a positive electrode active material 11 to both sides of a belt-like positive electrode current collector 10, then subjecting it to a vacuum drying treatment for 24 hours in an environment of 100 ° C., and further compressing by a roll press with an appropriate pressure force Produced by processing. The positive electrode material 5 is used by cutting it out with an external dimension of about 800 mm × 120 mm. Of course, the positive electrode material 5 is not limited to such a configuration.
[0022]
The negative electrode material 6 is formed by applying a negative electrode active material 13 to one side of a negative electrode current collector 12 made of copper foil. The negative electrode active material 13 is obtained by dispersing 91% by weight of artificial graphite and 9% by weight of powdered polyvinylidene fluoride using N-methylpyrrolidone (NMP) as a solvent. The negative electrode material 6 was coated with a negative electrode active material 13 on a strip-shaped negative electrode current collector 12, and then subjected to a vacuum drying treatment for 24 hours in an environment of 120 ° C., and further subjected to a compression treatment by a roll press with an appropriate pressure. Produced. As with the positive electrode material 5, the negative electrode material 6 is cut out and used with an outer dimension of about 800 mm × 120 mm. Of course, the negative electrode material 6 is not limited to such a configuration.
[0023]
The gel electrolyte 8 includes polyacrylonitrile (PAN), ethylene carbonate (EC), propylene carbonate (PC), lithium hexafluorophosphate (LiPF). ₆ A polyacrylonitrile-based gel electrolyte is used. The gel electrolyte 8 has a molar composition ratio of PAN: EC: PC: LiPF in which the above-described components are charged. ₆ = 12: 53: 27: 8. The gel electrolyte 8 is prepared by mixing a predetermined amount of EC and PC and heating to 150 ° C., and then mixing the predetermined amount of PAN and stirring to dissolve this PAN to form a viscous solution. Predetermined amount of LiPF ₆ It is made into a gel through a procedure of adding and dissolving.
[0024]
The positive electrode material 5 and the negative electrode material 6 described above are laminated with the main surfaces coated with the gel electrolyte 8 facing each other and sandwiching the separator 7. The positive electrode material 5 and the negative electrode material 6 are laminated while the distance and pressure thereof are kept constant by the adhesive action of the gel electrolyte 8 to constitute the battery assembly 2. The separator 7 has a width dimension of the positive electrode material 5 and the negative electrode material in order to prevent the outer package material 4 and the negative electrode material 6 from coming into contact when the battery assembly 2 is wrapped by the outer package material 4 as will be described later. The width dimension is slightly larger than 6. The battery assembly 2 is formed by folding a laminated body of the positive electrode material 5, the negative electrode material 6, and the separator 7 and having an overall outer dimension of about 80 mm × 130 mm × 3.5 mm.
[0025]
As the negative electrode terminal member 3, for example, a copper wire having a diameter of 50 μm is used, and a material obtained by cutting a copper wire into a rectangular shape at intervals of 75 μm is used. The negative terminal member 3 has a base end portion 3b joined to the negative electrode current collector 12 by spot welding or the like. In order to maintain the tensile strength, it is preferable to use the negative electrode terminal member 3 constituted by so-called vertical meshes in which each mesh is a long axis with respect to the longitudinal direction. As shown in FIG. 3, the negative electrode terminal member 3 has one end side in the longitudinal direction of the battery assembly 2 as a terminal lead portion 2a, and a tip portion 3a thereof protrudes.
[0026]
As the exterior material 4, a metal foil that is thin and lightweight, has excellent mechanical strength and moisture resistance, and can be folded without being bulky, specifically, an aluminum foil having a thickness of about 40 μm is used. As the exterior material 4, a material whose outer dimension is slightly larger than at least the outer dimension of the battery assembly 2 described above is used. As shown in FIG. 3, the exterior material 4 is folded in half from the central portion in the length direction with the crease portion 4 a positioned at the portion 2 b on the opposite side of the terminal lead-out portion 2 a of the battery assembly 2. The exterior material 4 has the front-end |

tip parts

4b and 4c which oppose on the terminal drawer | drawing-out part 2a side. The exterior material 4 is formed into a bag shape by forming both side surface

joint portions

4d and 4e by performing ultrasonic welding processing along both side surfaces orthogonal to the crease portion 4a.
[0027]
It is preferable to use a metal foil made of the same material as that of the current collector constituting the outermost peripheral layer of the battery assembly 2 for the exterior material 4. Since the outermost peripheral layer of the battery assembly 2 is constituted by the positive electrode current collector 10 as described above, an aluminum foil is used for the exterior material 4. Aluminum foil is suitable because it is lightweight and inexpensive. Of course, the exterior material 4 may be made of aluminum as a main component, and may be an aluminum alloy foil or a metal foil having an aluminum layer formed on the surface by vapor deposition or the like. As described above, an aluminum foil having a thickness of 40 μm is used for the exterior material 4, but a material having a thickness of 10 μm to 100 μm is used as appropriate depending on material strength, mass, and moisture permeability. The exterior material 4 preferably has a thickness dimension of 20 μm to 60 μm in consideration of pinhole freeness, workability, thickness and weight as the exterior.
[0028]
An insulating resin sheet 9 is applied to the exterior material 4 on the inner surfaces of the

front end portions

4b and 4c facing each other. The insulating resin sheet 9 is made of a polyethylene film having a length substantially equal to the width dimension of the exterior material 4, and is applied perpendicularly to the negative electrode terminal member 3 along the

front end portions

4b and 4c of the exterior material 4 as shown in FIG. It will be broken. The insulating resin sheet 9 is insulated from the exterior material 4 and the negative electrode terminal member 3 by forming a front end joint portion 4f by subjecting the

front end portions

4b and 4c on which the exterior material 4 is overlapped to a vacuum heating welding process. And the

tip portions

4b and 4c are sealed.
[0029]
The insulating resin sheet 9 has a length substantially equal to the width of the exterior material 4 and is configured so as not to cause a step at the tip joint portion 4f. However, at least the negative electrode terminal member 3 is covered. Of course, it is sufficient to have a sufficient length. In addition to the polyethylene film, the insulating resin sheet 9 may be made of a film material such as polyolefin, nylon, ionomer, polyethylene terephthalate, and the like, which has good properties for bonding to metal and low water permeability.
[0030]
In the above-described lithium ion secondary battery 1, the exterior material 4 is joined to the positive electrode current collector 10 to form a positive electrode terminal, and the negative electrode terminal member 3 having the base end 3 b joined to the negative electrode current collector 13 is provided. However, it is needless to say that the configuration is not limited thereto. The lithium ion secondary battery 1 may be provided with a pair of electrode terminal members that are respectively joined to the positive electrode current collector 10 and the negative electrode current collector 13.
[0031]
Further, the lithium ion secondary battery 1 may be configured such that the exterior material 4 is configured as a negative electrode terminal and a positive electrode terminal member joined to the positive electrode current collector 10 is provided. In this case, the lithium ion secondary battery 1 is folded so that the outermost peripheral layer of the battery assembly 2 becomes the negative electrode current collector 13, whereby the negative electrode current collector 13 and the exterior material 4 are electrically connected. So that The positive electrode terminal member is kept insulative with respect to the exterior material 4, and its tip portion protrudes to the outside.
[0032]
When the outermost peripheral layer of the battery assembly 2 is used as the negative electrode current collector 13 and the outer package material 4 is also used as the negative electrode terminal, it is preferable to use a copper foil as the outer package material 4. Of course, the exterior material 4 is formed by plating, vapor-depositing, or the like on the surface of nickel, iron, stainless steel, aluminum, or a metal foil made of at least one of these metals, or an alloy foil containing these metals. A metal foil may be used.
[0033]
The lithium ion secondary battery 1 is manufactured by the following method using the above-described components. That is, in the lithium ion secondary battery 1, the battery assembly 2 is sealed by the exterior material 4 with the tip 3 a of the negative electrode terminal member 3 protruding and exposed. As shown in FIG. 3, the lithium ion secondary battery 1 wraps the battery assembly 2 by folding the folded outer packaging material 4 at the

leading end portion

4 b and 4 c on the lead-out portion 2 a side from which the negative electrode terminal member 3 is pulled out. It becomes. In the lithium ion secondary battery 1, an insulating resin sheet 9 is applied to the inner surface of the

front end portions

4 b and 4 c with the negative electrode terminal member 3 sandwiched between the exterior material 4.
[0034]
The lithium ion secondary battery 1 was along both sides by performing ultrasonic welding processing over the entire area of both side surfaces orthogonal to the crease part 4a so that the exterior material 4 does not overlap with the electrode assembly 2. The

side joining portions

4d and 4e are formed and joined in a bag shape. The lithium ion secondary battery 1 has extremely good waterproof properties because the side

surface bonding portions

4d and 4e are not the portion from which the negative electrode terminal member 3 is drawn, but are bonded by resolidification of molten aluminum. And firmly joined.
[0035]
The lithium ion secondary battery 1 does not require a larger bonding width than the conventional laminate material for the

side bonding portions

4d and 4e, but may be formed with an equivalent width of 5 mm. In the lithium ion secondary battery 1, the side

surface bonding portions

4 d and 4 e can be bent inward relatively easily by using the aluminum foil for the exterior material 4. Therefore, since the thickness of the lithium ion secondary battery 1 is very small even when the side

surface bonding portions

4d and 4e are bent, the thickness dimension is almost the same as the thickness and dimension of the battery assembly 2, and is effective. Volume ratio.
[0036]
The lithium ion secondary battery 1 is formed by forming a tip joint portion 4f in which the exterior material 4 is subjected to vacuum heating welding processing on the

tip portions

4b and 4c overlapped to make the inside vacuum. In the lithium ion secondary battery 1, the negative electrode terminal member 3 is firmly joined to the tip joint portion 4f in a state where insulation with the exterior material 4 is securely held by melting the molten insulating resin sheet 9 in the mesh. It will be. In the lithium ion secondary battery 1, in order to pull out the negative electrode terminal member 3, the tip joint portion 4 f of the outer packaging material 4 is in a state where its waterproof property is slightly deteriorated with respect to the side

joint portions

4 d and 4 e. Accordingly, in the lithium ion secondary battery 1, when the insulating resin sheet 9 that partially insulates the negative electrode terminal member 3 is used, the insulating resin sheet 9 is longer by about 1 mm than the width dimension of the negative electrode terminal member 3. It is preferable to use the above.
[0037]
As described above, the lithium ion secondary battery 1 uses the insulating resin sheet 9 having a length dimension over the entire width direction at the front end joint portion 4f of the exterior material 4 so that there is no step and good waterproof characteristics. Consists of. In the lithium ion secondary battery 1, the tip joint portion 4 f may be formed by ultrasonic welding similarly to the side

joint portions

4 d and 4 e. The lithium ion secondary battery 1 is in a state in which the exterior material 4 is in close contact with the battery structure 2 by sealing the battery structure 2 by evacuating the interior of the exterior material 4. In the lithium ion secondary battery 1, since the outermost peripheral layer of the battery assembly 2 is constituted by the positive electrode current collector 10, the electrical continuity between the exterior material 4 and the positive electrode current collector 10 is reliably maintained. With this configuration, the lithium ion secondary battery 1 functions stably even when the exterior material 4 serves as a positive electrode terminal.
[0038]
The present invention is not limited to the lithium ion secondary battery 1 described above. For example, a positive electrode material obtained by applying a positive electrode active material capable of absorbing lithium ions to a positive electrode current collector, and a negative electrode material made of metallic lithium, Of course, the present invention can also be applied to a lithium primary battery including a polymer electrolyte. Further, the present invention can be applied to various batteries, for example, a battery using a liquid electrolyte. Furthermore, the present invention is also suitably applied to a so-called polymer battery in which a polymer electrolyte is sandwiched between a positive electrode material and a negative electrode material.
[0039]
The thin battery 20 shown in FIG. 4 is obtained by further improving the mechanical strength with respect to the lithium ion secondary battery 1 described above. The thin battery 20 is formed by sealing the exterior material 4 of the lithium ion secondary battery 1 with a resin film 21. The resin film 21 is formed into a bag shape with one opening 22 made of, for example, a polyolefin or a Teflon-based heat-shrinkable resin. The resin film 21 has an internal space that is slightly larger than the outer dimensions of the lithium ion secondary battery 1.
[0040]
The thin battery 20 is loaded in the sealing material 21 made of a resin film from the opening 22 with the lithium ion secondary battery 1 as shown in the figure, with the side opposite to the portion where the positive electrode terminal member 3 is exposed as the loading side. Is done. The thin battery 20 heat-treats the sealing material 21 with the tip 3 a of the negative electrode terminal member 3 exposed from the opening 22. In the thin battery 20, the sealing material 21 shrinks in accordance with the outer shape of the lithium ion secondary battery 1 and seals it.
[0041]
The thin battery 20 is covered with a sealing material 21 made of a heat-shrinkable resin film, so that the mechanical strength is improved. Since the thin battery 20 is in close contact with the outer peripheral portion of the lithium ion secondary battery 1 loaded when the sealing material 21 is subjected to heat treatment and contracts, the outer dimensions are almost the same as the lithium ion secondary battery 1. Composed.
[0042]
In addition, about the sealing material 21, it is preferable to shape | mold in the range close | similar to the magnitude | size in the range which does not have trouble in loading operation of the lithium ion secondary battery 1 so that a useless volume may not arise. The sealing material 21 is formed into an appropriate shape such as a cylindrical shape, a flat cylindrical shape, or an envelope shape in accordance with the shape of the lithium ion secondary battery 1.
[0043]
The thin battery 30 shown in FIG. 5 has a configuration in which the side

joint portions

4d and 4e formed on both side surfaces of the exterior material 4 are folded inward and sealed by the sealing body 25 in the lithium ion secondary battery 1 described above. It has the characteristics. The side

joint portions

4d and 4e are formed by performing ultrasonic welding on the exterior body 4 made of aluminum foil as described above. The

side joining portions

4d and 4e are very easy to bend and have a small thickness due to the material characteristics of the exterior body 4.
[0044]
In the thin battery 30, the lithium ion secondary battery 1 is loaded into the sealing body 25 through the opening 26 with the side opposite to the portion where the negative electrode terminal member 3 is exposed as shown in FIG. The thin battery 30 holds the side

joint portions

4d and 4e bent by the sealing body 25. The sealing body 25 also has a protective action for the lithium ion secondary battery 1 loaded together with the holding action of the side

joint portions

4d and 4e.
[0045]
In addition, about the sealing body 25, you may be comprised similarly to the heat-shrinkable resin film mentioned above. Further, the sealing body 25 may be a member obtained by molding the outer peripheral portion of the lithium ion secondary battery 1 in which the side

surface bonding portions

4d and 4e are bent in advance by a thermoplastic resin or a thermo / photocurable resin.
[0046]
The first embodiment thin battery 1A to the sixth embodiment thin battery 1F shown below based on the lithium ion secondary battery 1 described above, and the first comparative example thin battery 100A to 100A using a laminate as the exterior material. A third comparative example thin battery 100C was manufactured and evaluated.
[0047]
The first example thin battery 1A was manufactured by the lithium ion secondary battery 1 shown in the above-described embodiment. In the battery assembly 2A, a laminate composed of the positive electrode material 5, the negative electrode material 6, and the separator 7 was wound so as to be folded flat, and the outermost peripheral layer was configured as the positive electrode current collector 10 and the exterior material 4 was configured as the positive electrode terminal. The electrode terminal member 3 was formed by cutting a metal net obtained by braiding a copper wire having a diameter of 50 μm with a mesh of 75 μm intervals, and connecting the base end 3 b to the negative electrode current collector 12. An aluminum foil having a thickness of 40 μm was used for the exterior material 4 and ultrasonic welding was performed to form side-joined

portions

4d and 4e having a width of 5 mm.
[0048]
In the thin battery 1B of the second embodiment, the battery assembly 2B is formed by folding a laminated body composed of the positive electrode material 5, the negative electrode material 6 and the separator 7 and the outermost peripheral layer is the negative electrode current collector 12, and the outer packaging material 4 is the negative electrode terminal. It is the lithium ion secondary battery comprised as follows. The electrode terminal member 3 was formed by cutting a metal net formed by braiding an aluminum wire having a diameter of 50 μm with a mesh having an interval of 75 μm, and connecting the base end 3 b to the positive electrode current collector 10. A nickel foil having a thickness of 40 μm was used for the exterior material 4 and was subjected to ultrasonic welding to form side

joint portions

4d and 4e having a width of 5 mm.
[0049]
In the thin battery 1C of the third embodiment, the positive electrode material 5 is made of lithium nickelate (LiNiO). ₂ ) And non-graphitizable carbon is used for the negative electrode material 6, and is a lithium ion secondary battery prepared by the same process as the thin battery 1 </ b> A of the first embodiment described above. An aluminum foil having a thickness of 40 μm was used for the exterior material 4 and ultrasonic welding was performed to form side-joined

portions

4d and 4e having a width of 5 mm.
[0050]
In the fourth embodiment thin battery 1D, the positive electrode material 5 is made of lithium nickelate (LiNiO). ₂ ) Is used, and a lithium metal having a thickness of 300 μm is used for the negative electrode material 6, and is a lithium metal secondary battery produced by the same process as the above-described first embodiment thin battery 1A. The electrode terminal member 3 was connected by crimping the base end 3 b to the lithium metal of the negative electrode material 6. An aluminum foil having a thickness of 40 μm was used for the exterior material 4 and ultrasonic welding was performed to form side-joined

portions

4d and 4e having a width of 5 mm.
[0051]
The fifth embodiment thin battery 1E is a lithium primary battery using manganese dioxide as the positive electrode material 5 and metallic lithium as the negative electrode material 6 and made by the same process as the above-described first embodiment thin battery 1A. An aluminum foil having a thickness of 40 μm was used for the exterior material 4 and ultrasonic welding was performed to form side-joined

portions

4d and 4e having a width of 5 mm.
[0052]
The sixth example thin battery 1F is the same as the lithium ion secondary battery 20 shown as the second embodiment described above. After the first example lithium ion secondary battery 1A is manufactured, the side joining is performed. This is a lithium ion secondary battery in which the

parts

4d and 4e are folded inward and sealed with a sealing body 25 made of a heat-shrinkable tube.
[0053]
The first comparative example thin battery 100A is a conventional laminated film as an exterior body for sealing the battery assembly 101 after the battery assembly 101 is manufactured by the same process as the lithium ion secondary battery 1A of the first embodiment described above. This is a lithium ion secondary battery using 104. The laminate film 104 is made of a polyethylene terephthalate film having an outer layer thickness of 50 μm, an intermediate layer made of an aluminum foil having a thickness dimension of 20 μm, and an inner layer made of a polyethylene film having a thickness dimension of 150 μm. In the first comparative example thin battery 100A, the laminate film 104 wraps the battery assembly 101 in the same manner as the exterior material 4 of the lithium ion secondary battery 1A of the first example, and then impulses are formed along both side surfaces. A heat-melting treatment with a sealer is performed to form a heat-welded portion 105 having a width of 10 mm.
[0054]
In the second comparative example thin battery 100B, after the battery assembly 101 is manufactured by the same process as the fourth embodiment thin battery 1D described above, the conventional laminate film 104 is used as an exterior body for sealing the battery assembly 101. Lithium metal secondary battery. Similarly to the first comparative example thin battery 100A, the second comparative example thin battery 100B is also wrapped with a laminate film 104 and then heated and melted by an impulse sealer along both side surfaces to have a width of 10 mm. The heat welding part 105 is formed.
[0055]
The third comparative example thin battery 100C uses the conventional laminate film 104 as an exterior body for sealing the battery assembly 101 after the battery assembly 101 is manufactured by the same process as the fifth embodiment thin battery 1E described above. Lithium primary battery. Similarly to the first comparative example thin battery 100A, the third comparative example thin battery 100C is encased in the laminate film 104 and then subjected to a heat-melting treatment with an impulse sealer along both side surfaces to have a width of 10 mm. The heat welding part 105 is formed.
[0056]
For each of the thin battery 1A to 1F of the example and the thin batteries 100A to 100C of the comparative example, the results of the actual measurement of the thickness dimensions in a state where the side

surface bonding portions

4d and 4e and the heat welding portion 105 are bent inward are as follows. Table 1 below. In addition, about each secondary battery, the thickness dimension at the time of a full charge was measured.
[0057]
[Table 1]

[0058]
As is apparent from Table 1, each of the thin battery 1A through the sixth embodiment and the thin battery 1F through the sixth embodiment has a thickness dimension as compared with the first comparative thin battery 100A through the third comparative thin battery 100C. It is made thin up to about 15%.
[0059]
Next, the following evaluation tests were performed on the first example thin battery 1A to the sixth example thin battery 1F and the first comparative example thin battery 100A to the third comparative example thin battery 100C.
[0060]
The evaluation method of each example secondary battery (1A to 1D and 1F) and comparative example secondary battery (100A, 100B) is 0.5C charge / discharge under environmental conditions of temperature 60 ° C and humidity 60%. The cycle test was performed for about 70 days for 300 cycles, and the capacity retention rate from the initial battery capacity was measured and evaluated. Further, after the end of the charge / discharge cycle test, each secondary battery was evaluated by measuring the amount of moisture that had penetrated by analyzing the internal electrolyte. In addition, 0.5 C is a current value for discharging the rated capacity of the battery in 2 hours.
[0061]
The cycle test results of the example secondary batteries (1A to 1D and 1F) and the comparative example secondary batteries (100A, 100B) were as shown in Table 2 below.
[0062]
[Table 2]

[0063]
In addition, the evaluation method of the example primary battery 1E and the comparative example primary battery 100C is as follows: when it is left for 70 days in a high temperature and high humidity environment condition of a temperature of 60 ° C. and a humidity of 60%; The discharge capacity was measured and evaluated when left for 70 days. Further, after the standing test, each primary battery was evaluated by analyzing the internal electrolyte and measuring the amount of invaded water.
[0064]
Table 3 shows the results of leaving tests of the example primary battery 1E and the comparative example primary battery 100C.
[0065]
[Table 3]

[0066]
As is clear from Tables 2 and 3, the thin battery 1A through the sixth embodiment and the thin battery 1F through the sixth embodiment are moisture-proof as compared with the first comparative thin battery 100A through the third comparative thin battery 100C. Excellent characteristics. Accordingly, each of the example thin batteries 1A through the sixth example thin batteries 1F has a longer battery life and is thinner than the first comparative example thin battery 100A through the third comparative example thin battery 100C. The volume energy density is high.
[0067]
【The invention's effect】
As described above in detail, according to the thin battery according to the present invention, the thin battery structure is sealed with the exterior material made of metal foil, so that it is thinner, smaller, lighter and has a volume energy. The battery has a long battery life and extremely high performance due to its high density and excellent moisture resistance. Furthermore, since it is covered with the sealing material, the mechanical strength can be improved. Therefore, the thin battery is suitably used as a power source for a portable electronic device or the like, and realizes its small size, light weight, and multiple functions.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a configuration of a lithium metal secondary battery shown as an embodiment of a thin battery according to the present invention.
FIG. 2 is a longitudinal sectional view of a main part for explaining the configuration of a battery structure provided in the lithium metal secondary battery.
FIG. 3 is an explanatory diagram of a sealing operation of a battery assembly by an exterior material in the lithium metal secondary battery.
FIG. 4 shows another embodiment of the thin battery according to the present invention, and is an explanatory view of the sealing operation of the battery assembly.
FIG. 5 shows another embodiment of the thin battery according to the present invention, and is an explanatory diagram of a sealing operation using a sealing material.
FIG. 6 is a perspective view of a conventional lithium metal secondary battery.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lithium metal secondary battery (thin battery), 2 battery assembly, 2a terminal drawer part, 3 negative terminal member (electrode terminal member), 4 exterior body, 4a crease part, 4d, 4e side surface joining part, 4f tip joining part, DESCRIPTION OF SYMBOLS 5 Positive electrode material, 6 Negative electrode material, 7 Seberator, 8 Gel electrolyte (polymer electrolyte), 9 Insulating sheet, 10 Positive electrode collector, 11 Positive electrode active material, 12 Negative electrode collector, 13 Negative electrode active material
Sealing material, 6 Sealing material, 7 Laminating material, 8 Positive terminal member, 9 Negative terminal member, 10 Conductor

Claims

At least a positive electrode material, a negative electrode material, and a battery structure formed by laminating a polymer electrolyte, an electrode terminal member, and an exterior material made of metal foil,
The exterior material encloses the battery assembly with the tip of the electrode terminal member exposed, and the outer peripheral portion is joined , and is electrically joined to either the positive electrode material or the negative electrode material. By configuring the electrode terminal ,
The electrode terminal member of the other polarity is applied to the insulating resin sheet and pulled out of the exterior material,
A thin battery characterized in that the battery assembly is sealed by covering the outer covering material with a sealing material in a state where the tip portion of the electrode terminal member is exposed to the outside.

As the exterior material, a metal foil made of at least one of aluminum, nickel, iron, stainless steel, and copper, or an alloy foil containing these metals and a metal foil plated with these metals are used. The thin battery according to claim 1.

As the exterior material, an aluminum foil, an aluminum alloy foil, or a metal foil having an aluminum layer formed on the surface thereof is used, and a positive electrode terminal is configured by being electrically joined to a positive electrode current collector constituting the positive electrode material. The thin battery according to claim 1.

For the exterior material, a metal foil made of any one or more of nickel, iron, stainless steel and copper, or a metal foil having these metal layers formed on the surface by alloy foil or plating containing these metals is used. 2. The thin battery according to claim 1, wherein a negative electrode terminal is formed by being electrically joined to a negative electrode current collector constituting the negative electrode material.

2. The exterior material according to claim 1, wherein the outer peripheral portion is joined by being subjected to ultrasonic melting treatment in a state in which an insulating resin sheet is applied to the electrode terminal member and pulled outward. Thin battery.

The thin battery according to claim 5, wherein the insulating resin sheet has an outer dimension that is larger than a width of the electrode terminal member and smaller than one side of the exterior material from which the electrode terminal member is drawn.

2. The outer periphery of the exterior material is joined to the outer peripheral portion except the crease portion in a state where the battery assembly is wrapped with the side facing the lead portion of the electrode terminal member as a crease portion. Thin battery.

The sealing material is formed in a bag shape having one side opened by a synthetic resin material, and the tip of the electrode terminal member is exposed outwardly from the opening portion of the battery assembly sealed by the exterior material. The thin battery according to claim 1, wherein the thin battery is sealed.

2. The thin battery according to claim 1, wherein the sealing material seals the entirety of the exterior material that seals the battery structure in a state in which a bonded outer peripheral portion is folded inward.

2. The thin battery according to claim 1, wherein the sealing material is made of a heat-shrink film, and is subjected to heat treatment in a state of wrapping the battery structure sealed by the exterior material.

The battery assembly includes at least a positive electrode material formed by depositing a positive electrode active material that absorbs lithium ions on a strip-shaped current collector, and a negative electrode material formed by depositing metallic lithium on the strip-shaped current collector, The thin battery according to claim 1, wherein the thin battery has a non-aqueous electrolyte, a solid electrolyte, or the polymer electrolyte made of a gel electrolyte and constitutes a lithium primary battery.

The battery assembly includes the positive electrode material formed by depositing a positive electrode active material that reversibly inserts and removes lithium on the belt-shaped current collector, and metal lithium, a lithium alloy, or lithium on the belt-shaped current collector. A lithium secondary battery comprising: the negative electrode material formed by depositing a negative electrode active material to be coated; and the polymer electrolyte comprising a non-aqueous electrolyte, a solid electrolyte, or a gel electrolyte. Item 2. The thin battery according to Item 1.