JP4382949B2

JP4382949B2 - Multilayer electric double layer capacitor

Info

Publication number: JP4382949B2
Application number: JP2000054006A
Authority: JP
Inventors: 和雄生田; 雄一堀; 誠東別府; 健児島津
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2000-02-29
Filing date: 2000-02-29
Publication date: 2009-12-16
Anticipated expiration: 2020-02-29
Also published as: JP2001244149A

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer electric double-layer capacitor which is low in internal resistance, high in electrostatic capacity and high in productivity. SOLUTION: A cell 14 for an electric double-layer capacitor is constituted into a structure, where an almost rectangle-shaped laminate formed by laminating a polarized electrode 3 on the surface on at least one side of the surfaces of a current-collecting body 2 is housed between two almost rectangle-shaped separators 5 and 5 and at the same time, a conductor 1 for forming terminals is provided on at least a part of the side parts of the body 2 and the conductor 1 is folded up where the conductor 1 pinches the end parts of the separators 5 and 5 to form the terminals 6 on the end parts of the separators 5 and 5 and a multilayer electric double-layer capacitor 20 is manufactured into a structure that the capacitor 20 is provided with a plurality of the cells 14.

Description

【０００１】
【発明の属する技術分野】
本発明は、分極性電極と集電体とセパレータとを積層して形成する電気二重層コンデンサに関する。
【０００２】
【従来技術】
最近、大電流の充放電が可能な電気二重層コンデンサが注目されている。電気二重層コンデンサは、電極と電解液との界面においてイオンの分極によりできる電気二重層を利用したコンデンサであり、従来のコンデンサに比較して大容量の静電容量を充電できるとともに、急速充放電が可能であり、その応用が期待されている。
【０００３】
かかる電気二重層コンデンサにおいては、概略矩形板状の集電体の両面に分極性電極を積層した積層体を正極または負極をなす一単位の電極対として、これを交互に積層するとともに、該電極対間をセパレータにて絶縁し、該積層体をガスケット等のハウジング内に収納するか、またはアルミラミネート等のフィルムによって封止した構成からなる積層型電気二重層コンデンサが知られている。
【０００４】
この積層型電気二重層コンデンサは、けん回型に電気二重層コンデンサに対して、角形状の電気二重層コンデンサを作製でき、電気二重層コンデンサ同士または他の部材との実装性が高く、かつ内部抵抗が低めることができることが知られている。
【０００５】
また、上記積層型電気二重層コンデンサは、それぞれ前記集電体辺部の一部に突出する端子を設けるとともに、正極をなす該端子同士、負極をなす該端子同士をそれぞれ電気的に接続し、さらにこれを取り出し電極に接続して電気二重層コンデンサの封止部材外部に突出させて外部回路と電気的に接続する方法が知られている。
【０００６】
【発明が解決しようとする課題】
しかしながら、かかるセパレータ−分極性電極−集電体−分極性電極−セパレータを一単位とする電気二重層コンデンサ用セル（以下、単にセルと略す。）を複数層積層した積層型電気二重層コンデンサにおいては、製造時または使用時にセル内およびセル間が位置ずれを生じやすく、特にセル内の位置ずれによって各部材間の接触状態および接触面積が変化し、例えば、分極性電極間の位置ずれによって静電容量が低下したり、分極性電極と集電体との位置ずれによって電気二重層コンデンサの内部抵抗値が増大したり、場合によっては分極性電極とセパレータとが位置ずれして分極性電極同士が接触しショートしてしまう恐れがあった。
【０００７】
そこで、例えば、分極性電極と集電体との積層体を袋状体のセパレータ内に前記集電体に設けた端子部がセパレータから突出するように収納することにより、分極性電極同士が接触してショートすることを防止する方法が知られている。
【０００８】
しかしながら、かかる方法によっても集電体と分極性電極との積層体の位置ずれを防止することはできず、また、セパレータも固定されてはいないために場合によっては位置ずれして分極性電極間が接触し、ショートする恐れがあり、さらに端子部の厚みが薄く、かつ前記セパレータから突出して形成されるために、端子部の強度および保形性が低く、端子部または端子部と集電体との界面にクラック等が生じて内部抵抗値が増大し、場合によっては断線する恐れがあった。さらにまた、前記セルの集電体部と端子部との厚み差が大きく、積層時の位置ずれの一因となっていた。
【０００９】
また、特開平１０−７４６７２号公報では、集電体の一辺部に厚みの厚い端子形成用の金属板を設け、該板の不要部分を切除することによって集電体の厚みよりも厚い端子を作製し、該端子の厚みを前記集電体と分極性電極との積層体の厚みに近似させることによって、端子の強度および保形性を高めることができるとともに、セル積層時の位置ずれを低減できることが記載されている。
【００１０】
しかしながら、かかる方法においても、集電体、分極性電極、セパレータが接着されてはいないために各層間の位置ずれを防止することができず、また、前記端子はセパレータから突出した形状となるために、端子は機械的な衝撃を受けやすく、また、上述した端子形成用の金属板を加工する際、金属板に破損や変形が発生したり、集電体と端子との界面にクラックが生じる恐れがあり、内部抵抗値の低減効果は充分とはいえなかった。
【００１１】
本発明は、前記課題を解決するためになされたもので、その目的は、電気二重層コンデンサ用セル内の集電体、セパレータ、分極性電極の位置ずれを防止でき、静電容量を高め、内部抵抗値を低減できるとともに、複数の前記セルを容易に積層できる生産性の高い積層型電気二重層コンデンサを提供することにある。
【００１２】
【課題を解決するための手段】
本発明者等は、前記課題に対し、特に電気二重層コンデンサ用セルの構造について検討した結果、２枚のセパレータ間に集電体と分極性電極とを収納し、かつ前記集電体の辺部に端子形成用導電体を設け、前記セパレータの辺部を挟持するように複数回前記端子形成用導電体を折り畳んで端子とすることによって、前記セル内の集電体−分極性電極−セパレータ間の位置ずれを低減し、また、端子がセパレータによって補強され、かつ厚い端子を形成できることから、端子の強度、保形性を高めることができる結果、高静電容量化と低内部抵抗値化とを同時に達成できるとともに、セル積層時のセルの部分的な厚み差による位置ずれを防止でき、生産性が向上することを知見した。
【００１３】
すなわち、本発明の電気二重層コンデンサは、２枚の概略矩形状のセパレータ間に、集電体の少なくとも一方の表面に分極性電極を積層した概略矩形状の積層体を収納するとともに、前記集電体辺部の少なくとも一部に、端子形成用導電体を設け、該導電体を前記２枚のセパレータの端部を挟持するように前記端子を形成してなる電気二重層コンデンサ用セルを複数具備することを特徴とするものである。
【００１４】
ここで、前記２枚のセパレータが袋状体であること、前記端子形成用導電体の折り畳み部同士を一部溶着したこと、前記電気二重層コンデンサ用セルにおける集電体と分極性電極との積層体を収納した部分の厚みが、前記セルの前記端子を形成した部分の厚みと同じであることが望ましい。
【００１５】
また、正極と負極をなす前記端子が形成された複数の正極および負極をなす前記電気二重層コンデンサ用セルを、前記正極と負極をなす端子間が接触しないように交互に積層するとともに、前記正極をなす端子同士および前記負極をなす端子同士をそれぞれ電気的に接続してなることが望ましい。
【００１６】
さらに、複数の前記正極および負極をなす電気二重層コンデンサ用セルの前記端子およびセパレータを貫通する貫通孔を形成し、該貫通孔内に正極および負極をなす２つの導電性棒状体をそれぞれ貫通させて、前記電気二重層コンデンサ用セルを積層、固定してなることがのぞましい。
【００１７】
また、前記正極および負極をなす端子が、前記セル積層体の同じ側面部に設けられてもよく、この場合には前記負極をなす電気二重層コンデンサ用セル１枚を介在させて配設された前記正極をなす電気二重層コンデンサ用セルの端子同士を、前記負極をなす電気二重層コンデンサ用セルの前記２枚のセパレータ辺部に、該２枚のセパレータ辺部間を挟持するように形成された導体を介して電気的に接続してなることが望ましい。
【００１８】
さらに、前記正極をなす端子と負極をなす端子とが、前記セル積層体の対向する側面に設けられてもよい。
【００１９】
【発明の実施の形態】
まず、本発明の電気二重層コンデンサを製造する方法の一例について、その一部である電気二重層コンデンサ用セル（以下、単にセルと略す。）の製造工程を示す図１の概略平面図および図２の概略断面図を基に説明する。
まず、概略矩形形状の端子形成用導電体（以下、単に導電体と略す。）１を一辺に設けた集電体２を準備し、その集電体２の両面に分極性電極３、３を積層する（工程（ａ）参照）。
【００２０】
分極性電極３は、望ましくは概略矩形形状で、例えば０．１〜３ｍｍ、特に０．１５〜１ｍｍ厚みの板状体からなり、活性炭を含有し、高い比表面積を有するものからなる。また、分極性電極３には後述する電解液が充填される。
【００２１】
一方、導電体１および集電体２は、１０〜５０μｍ厚みのアルミニウム、タンタル、チタン、、銀白金、金等の金属箔からなることが望ましく、中でも価格、抵抗値、加工性、耐久性の点でアルミニウムを主成分とする金属箔からなることが望ましい。
【００２２】
導電体１は、集電体２の一辺部に一体的に形成され、具体的には、例えば上記金属箔を導電体１と集電体２とを合わせた形状にカットして一体物として形成されるか、または導電体１と集電体２とを別体として形成した後これらの端部間を接合することによっても形成できる。
【００２３】
また、集電体２の導電体１を形成する位置は、図３に示すように、（Ａ）集電体２の１つの辺部全体に形成したもの、（Ｂ）集電体２の辺部の一部、特に該辺の長さに対して半分以下の幅に突出して形成したもの、（Ｃ）（Ａ）または（Ｂ）の構成に加えて、導電体１を集電体２の導電体１を形成した辺の頂部より外側にはみ出したはみ出し部１ａを形成したものが挙げられる。
【００２４】
なお、（Ａ）の構成によれば、容易に製造できるとともに後述する端子６の強度、保形性を高めることができ、（Ｂ）の構成において、後述する正極をなすセル１４ａと負極をなすセル１４ｂとを交互に積層する時に、隣接するセルの端子間が接触しないように形成することができる結果、正極をなす端子と負極をなす端子とを積層体の同じ側面に形成できる。また、（Ｃ）の構成によれば、前記はみ出し部を集電体表面側に折り返すことによって端子の厚みをさらに厚くでき、端子の強度を高めることができるとともに、セルの端子形成部の厚みをセルの集電体部の厚みに近似させてセルを安定して積層することができる。
【００２５】
次に、上記集電体２と分極性電極３、３との積層体を、導電体１の一部、具体的には、後述する導電体１の折り畳み部が突出するように２枚のセパレータ５、５内に収納する（工程（ｂ）参照）。この時、セパレータ５内に収納される導電体１の幅は、端子６の幅となるよう、すなわち端子６の高さ分だけ集電体２および分極性電極３の積層体の辺がセパレータ５の辺よりも内側になるように配設されることが望ましい。
【００２６】
セパレータ５として、具体的には、電解紙、ポリエチレン不織布、ポリプロピレン不織布、ポリエステル不織布、テフロン不織布、クラフト紙、マニラ麻シート、ガラス繊維シートなどが使用可能であるが、セパレータ５の厚みは０．０１〜０．１ｍｍ、特に０．０２〜０．０７ｍｍであることが望ましい。
【００２７】
ここで、セパレータ５、５は、少なくとも導電体１が突出する辺間が開口し、特に、２枚のセパレータ５、５の一辺間が接触固定されたものであることが分極性電極３の位置ずれを防止する上で望ましく、具体的には、１枚のセパレータ５形成用の層状体を中央部で折り畳んで２枚としたもの、２枚のセパレータ５、５の少なくとも一辺間を接着したもの、２枚のセパレータを袋状体としたもの等が挙げられる。
【００２８】
また、上記セパレータ５については、特に導電体１が突出する辺と対向する辺間が接触固定されたものであることが望ましい。なお、図１によれば、セパレータ５、５は、導電体１が突出した辺部間が開口しており、また、前記導電体１のはみ出し部１ａが開口して、それ以外のセパレータ５、５間が接触固定された袋体状となっており、かかる構成によれば、集電体２−分極性電極３−セパレータ５間の位置ずれをさらに防止できる。
【００２９】
次に、導電体１のセパレータ５から突出する部分を一方のセパレータ５を挟持するように折り畳んだ（工程（ｃ）参照）後、該折り畳み部を反対方向に折り畳んで他方のセパレータ５の辺部を挟持し、セパレータ５、５の辺部同士を挟持して重ね合わせ、固定するとともに、導電体１を２回以上折り曲げた少なくとも４層の導電体１からなる端子６を形成する（工程（ｄ）参照）。なお、上記折り畳み回数は３回以上であってもよく、端子６の厚みを制御できる。
【００３０】
この時、端子６の厚みを均一化するためには、導電体１の集電体２と接触する辺と対向する辺を集電体２および分極性電極３の積層体の導電体１を形成した辺と合わせるように折り畳むことが望ましく、また、導電体１の最後に折り畳む折り目が集電体２の導電体１形成辺部側に位置するセパレータ５の辺部に一致するように調整することが、セル１４の容積を小さくして後述する積層型電気二重層コンデンサ２０の小型化を図る点で望ましい。
【００３１】
ここで、上記折り畳み回数は３回以上であってもよく、また、所望により、導電体１の集電体２を形成した辺の頂部より外側にはみ出したはみ出し部１ａを折り畳んだ部分等の導電体１突出部７をセパレータ５表面に位置する導電体１の折り畳み部８表面に、これらの間を折り目として折り畳んでもよい。なお、図１によれば、上記３回目の折り畳みは１回目および２回目の折り畳み方向と直交する方向に折り畳まれる。
【００３２】
これによって、端子６の厚みを厚くでき、端子６の強度を高めて分極性電極３の位置ずれをさらに防止することができるとともに、セル１４の端子６形成部の厚みをセル１４における集電体２および分極性電極３の積層体部の厚みに、望ましくは同じとなるように近似させることによって、セルを安定して積層することができるとともに、セル１４の端子６に部分的な応力集中が発生することがなく、端子６、および端子６と集電体２との界面での内部抵抗の増大を防止することができる（工程（ｅ）参照）。
【００３３】
また、上記導電体１のはみ出し部７または３回以上折り畳む際の最後の折り畳みを行う前にセパレータ５辺部から突出する部分等の導電体１突出部７を超音波溶接やレーザー溶接等の公知の溶接方法を用いて溶接することによって一体化することにより、導電体１突出部７および端子６の強度および剛性を高めることができる。
【００３４】
さらに、所望により、端子６がセパレータ５辺部の一部、特に該辺の半分以下の幅、すなわち同じ側の辺部に端子を積層したセル１４の積層体において隣接するセル１４の端子６間が接触しないように形成されるものについては、前記セパレータ５の端子６を形成した辺部における端子６と接触しない領域、特にセパレータ５辺部の中心から線対称となる部分に、２枚のセパレータ５、５を挟持する導体１０を形成する。
【００３５】
導体１０は、アルミニウム、タンタル、チタン、鉄、コバルト、ニッケル、銅、銀、白金、金の群から選ばれる少なくとも１種を含有する金属箔または金属板からなるクリップであることが望ましく、これによって集電体２と分極性電極３の位置ずれをさらに小さくできるとともに、同じ側面に正極および負極をなす端子６を形成したセル１４積層体において、セル１枚を介在させて隣接するセル１４、１４の端子６、６間を導体１０とそれぞれ接触させることによって、該端子６、６間を電気的に接続することができる。なお、セル１４の導体１０形成部の厚みは端子６形成部の厚みと同じであることが望ましい。
【００３６】
さらに、所望により、端子６とセパレータ５とを貫通する貫通孔１２、さらに導体１０とセパレータ５とを貫通する貫通孔１２を形成して電気二重層コンデンサ用セル（以下、単にセルと略す）１４を作製することができる（図１（ｆ）参照）。
【００３７】
そして、上記セル１４を隣接するセル１４間の端子６、６間が接触しないようにして複数層積層するとともに、一枚おきのセル１４の端子６、６間を電気的に接続した２組の端子群をそれぞれ正極用の端子群および負極用の端子群とし、これら端子群の一部にそれぞれリード１５をそれぞれ接続する。
【００３８】
さらに、上記セル１４の積層体をアルミラミネート等の封止材１６内にリード１５が外部に突出するように収納した後、セル１４の分極性電極３とセパレータ５内に電解液を注入し、リード１５を挟み込んだ状態でセル１４の積層体を封着することによって本発明の積層型電気二重層コンデンサ２０を作製することができる。
【００３９】
なお、電解液としては、硫酸や硝酸等の水溶液や、プロピレンカーボネート、γ−ブチロラクトン、Ｎ，Ｎ−ジメチルホルムアミド、エチレンカーボネート、スルホラン、３−メチルスルホラン等の有機溶媒と４級アンモニウム塩、４級スルホニウム塩、４級ホスホニウム塩等の電解質を組み合わせた有機溶液が使用可能である。
【００４０】
また、上述したように端子６および導体１０に貫通孔１２、１２を形成したセル１４については、セル１４の貫通孔１２、１２をそれぞれ導電性棒状体１８に貫通させて積層した後、導電性棒状体１８の両端部を変形させるか、またはネジ止めしてセル１４をかしめることによってセル１４の積層体の位置ずれをさらに防止することができる。
【００４１】
さらに、集電体２の辺部全体に端子６を形成したセル１４を積層する際には、正極セル１４ａの端子６と負極セル１４ｂの端子６とが対向するように積層すればよく、また、上述した導電体突出部７を突出させた状態で積層するとともに、該導電体突出部７を隣接するセル１４の外周部を経由して次のセル１４の端子６と接触するように折り曲げることにより、端子６、６間を電気的に接続できる。
【００４２】
また、図１、２のセル１４は集電体２の両面に分極性電極３、３が積層されたものであったが、本発明はこれに限られるものではなく、例えば、セル１４の積層体の積層端部に位置するセルについては、集電体２の片面に分極性電極３が形成されたものであってもよい。
【００４３】
（電気二重層コンデンサの構成）
図４に、上述した方法によって得られる本発明の積層型電気二重層コンデンサの一例についての概略断面図を示す。
図４によれば、積層型電気二重層コンデンサ２０は、セル１４が複数枚積層された構成からなり、セル１４の積層体は封止材１６内に収納、封止されている。なお、セル１４は正極をなすセル（以下、単に正極セルと略す。）１４ａと負極をなすセル（以下、単に負極セルと略す。）１４ｂとが交互に積層されている。
【００４４】
また、セル１４は、概略矩形形状の分極性電極３、３が両面に積層された概略矩形形状の集電体２を２枚のセパレータ５内に収納しており、また、セパレータ５の一辺には、集電体２辺部と接続された導電体１を複数回以上折り畳んで少なくとも４層以上多層化された導電体１を具備するとともに、セパレータ５の辺２枚が介在する端子６が形成されている。
【００４５】
ここで、図４によれば、セパレータ５の端子６が形成された辺と対向する辺部においては、２枚のセパレータ５、５同士が接着または折り返しによって接触固定されており、望ましくは、セパレータ５、５の端子６が形成された辺部以外の辺部間が接触固定されている。
【００４６】
また、図４によれば、正極セル１４ａの端子６はセパレータ５の辺部のうちの一部のみに形成されており、隣接する負極セル１４ｂの端子（図示せず）とは接触しないように形成されている。さらに、図４によれば、負極セル１４ｂを１枚を介装して対峙する端子６、６間は、負極セル１４ｂのセパレータ５、５を挟持するように設けられた導体１０によって電気的に接続されている。
【００４７】
また、正極セル１４ａの端子６または導体１０の一部と接続するリード１５が、図４によれば、セル１４積層体のほぼ中央部にセル１４と平行して配設され、リード１５が封止材１６の外部に突出している。また、図示しないが、負極セル１４ｂについても同様にリード１５が形成されている。そして、封止材１６外部に突出した２つのリード１５を取り出し電極として外部回路の端子（図示せず）と接続することによって電気二重層コンデンサ２０を外部回路（図示せず）と接続することができる。
【００４８】
さらに、図４によれば、端子６および導体１０それぞれを貫通する貫通孔１２が形成され、貫通孔１２内にはリベットまたはボルト等の金属等からなる導電性棒状体１８が配設されている。これによって、セル１４積層時の位置決めが容易にでき、セル１４、１４間の位置ずれを防止することができるとともに、複数の端子６および導体１０間を確実に接続することができ、内部抵抗値を低減することができる。
【００４９】
なお、図示しないが、上述の導体１０、リード１５、貫通孔１２、導電性棒状体１８は負極セル側にも形成され、正極セルと同様に電気的に接続される。
【００５０】
また、図４のセル１４の積層体における積層端部に位置するセル１４については、セル１４積層体内部のセルと同じ構成からなるが、本発明はこれに限られるものではなく、前記端部のセル１４については、集電体２の片面に分極性電極３が形成され、前記端部のセル１４は前記積層端部側が集電体が直接セパレータに接触したものであってもよい。
【００５１】
【発明の効果】
以上、詳述したとおり、本発明の積層型電気二重層コンデンサによれば、２枚のセパレータ間に集電体と分極性電極とを収納し、かつ前記集電体の辺部に、一部が前記セパレータの開口部より突出する端子形成用導電体を設け、前記セパレータの辺部を挟持するように複数回前記端子形成用導電体を折り畳んで端子を形成するとともに、前記端子によって２枚のセパレータの辺部同士を挟持して重ね合わせ、固定ができることから、前記セル内の集電体−分極性電極−セパレータ間の位置ずれを低減し、また、端子をセパレータの辺部に設け、かつ厚い端子を形成できることから、端子の強度、保形性を高めることができる高静電容量化と低内部抵抗値化とを同時に達成できるとともに、セル積層時のセルの部分的な厚み差による位置ずれを防止でき、生産性が向上する。
【図面の簡単な説明】
【図１】本発明の電気二重層コンデンサを製造する方法の一例について、その一部工程を説明するための概略平面図である。
【図２】図１についての概略断面図である。
【図３】本発明の電気二重層コンデンサを製造する方法の一例について、導電体と集電体との形成例を説明するための模式図である。
【図４】本発明の電気二重層コンデンサの一例についての概略断面図である。
【符号の説明】
１端子形成用導電体
１ａはみ出し部
２集電体
３分極性電極
５セパレータ
６端子
７導電体突出部
８折り曲げ部
１０導体
１２貫通孔
１４電気二重層コンデンサ用セル
１５リード
１６封止材
１８導電性棒状体
２０積層型電気二重層コンデンサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric double layer capacitor formed by laminating a polarizable electrode, a current collector, and a separator.
[0002]
[Prior art]
Recently, electric double layer capacitors capable of charging and discharging a large current have attracted attention. An electric double layer capacitor is a capacitor that uses an electric double layer formed by the polarization of ions at the interface between the electrode and the electrolyte. It can charge a larger capacitance than a conventional capacitor, and can be charged and discharged quickly. Is possible and its application is expected.
[0003]
In such an electric double layer capacitor, a laminate in which polarizable electrodes are laminated on both sides of a substantially rectangular plate-like current collector is alternately laminated as a unit electrode pair constituting a positive electrode or a negative electrode, and the electrodes A multilayer electric double layer capacitor is known in which a pair is insulated by a separator and the laminate is housed in a housing such as a gasket or sealed with a film such as an aluminum laminate.
[0004]
This multilayer type electric double layer capacitor can produce a square electric double layer capacitor in comparison with the electric double layer capacitor in a spiral type, has high mountability between electric double layer capacitors or other members, and has an internal It is known that the resistance can be lowered.
[0005]
Further, the multilayer electric double layer capacitor is provided with a terminal projecting at a part of the current collector side part, and electrically connects the terminals forming the positive electrode and the terminals forming the negative electrode, Furthermore, a method is known in which this is connected to an extraction electrode and protruded outside the sealing member of the electric double layer capacitor to be electrically connected to an external circuit.
[0006]
[Problems to be solved by the invention]
However, in a multilayer electric double layer capacitor in which a cell for an electric double layer capacitor (hereinafter simply referred to as a cell) having such separator-polarizable electrode-current collector-polarizable electrode-separator as a unit is laminated. In the case of manufacturing or use, misalignment is likely to occur in the cell and between the cells. In particular, the misalignment in the cell changes the contact state and the contact area between the members. The electric capacity decreases, the internal resistance value of the electric double layer capacitor increases due to misalignment between the polarizable electrode and the current collector, or in some cases, the polarizable electrode and the separator misalign, Could come into contact and short circuit.
[0007]
Therefore, for example, by storing a laminate of a polarizable electrode and a current collector in a bag-shaped separator so that a terminal portion provided on the current collector protrudes from the separator, the polarizable electrodes are in contact with each other. Thus, a method for preventing a short circuit is known.
[0008]
However, such a method cannot prevent the misalignment of the laminate of the current collector and the polarizable electrode. Also, since the separator is not fixed, the misalignment may occur between the polarizable electrodes. The terminal part is thin, and the terminal part is formed so as to protrude from the separator. Therefore, the terminal part has low strength and shape retention, and the terminal part or the terminal part and the current collector As a result, cracks or the like are generated at the interface between the two and the internal resistance value is increased. Furthermore, the thickness difference between the current collector portion and the terminal portion of the cell is large, which is a cause of positional deviation during stacking.
[0009]
In JP-A-10-74672, a thick metal plate for forming a terminal is provided on one side of the current collector, and a terminal thicker than the thickness of the current collector is formed by cutting away unnecessary portions of the plate. Producing and approximating the thickness of the terminal to the thickness of the laminate of the current collector and polarizable electrode can increase the strength and shape retention of the terminal and reduce misalignment during cell lamination. It describes what you can do.
[0010]
However, even in such a method, the current collector, the polarizable electrode, and the separator are not bonded to each other, so that it is impossible to prevent displacement between the layers, and the terminal has a shape protruding from the separator. In addition, the terminal is easily subjected to mechanical shock, and when the above-described metal plate for forming a terminal is processed, the metal plate is damaged or deformed, or a crack is generated at the interface between the current collector and the terminal. There was a fear that the effect of reducing the internal resistance value was not sufficient.
[0011]
The present invention has been made in order to solve the above-mentioned problems, and its purpose is to prevent the displacement of the current collector, separator, and polarizable electrode in the electric double layer capacitor cell, and to increase the capacitance. An object of the present invention is to provide a highly productive multilayer electric double layer capacitor that can reduce the internal resistance and can easily stack a plurality of the cells.
[0012]
[Means for Solving the Problems]
As a result of studying the structure of the electric double layer capacitor cell in particular, the present inventors have accommodated the current collector and the polarizable electrode between two separators, and the sides of the current collector. Current collector in the cell-polarizable electrode-separator by providing a terminal-forming conductor in the part and folding the terminal-forming conductor a plurality of times so as to sandwich the side of the separator. As the terminal is reinforced with a separator and a thick terminal can be formed, the strength and shape retention of the terminal can be improved, resulting in higher capacitance and lower internal resistance. It has been found that productivity can be improved by preventing misalignment due to partial thickness differences of cells during cell stacking.
[0013]
That is, the electric double layer capacitor of the present invention accommodates a substantially rectangular laminate in which a polarizable electrode is laminated on at least one surface of a current collector between two roughly rectangular separators, and the collector. A plurality of electric double layer capacitor cells in which a terminal-forming conductor is provided on at least a part of the side of the electric body and the terminal is formed so as to sandwich the end of the two separators. It is characterized by comprising.
[0014]
Here, the two separators are bag-like bodies, the folded portions of the terminal forming conductors are partially welded, and the current collector and the polarizable electrode in the electric double layer capacitor cell It is desirable that the thickness of the portion containing the laminated body is the same as the thickness of the portion of the cell where the terminal is formed.
[0015]
In addition, the positive electrode and the negative electrode are formed by alternately laminating the plurality of positive electrodes and the electric double layer capacitor cells forming the negative electrode so that the terminals forming the positive electrode and the negative electrode are not in contact with each other. It is desirable that the terminals forming the negative electrode and the terminals forming the negative electrode are electrically connected to each other.
[0016]
Furthermore, a through hole is formed through the terminal and separator of the electric double layer capacitor cell forming a plurality of the positive and negative electrodes, and two conductive rods forming the positive electrode and the negative electrode are respectively inserted into the through holes. The electric double layer capacitor cell is preferably laminated and fixed.
[0017]
Further, the terminals forming the positive electrode and the negative electrode may be provided on the same side surface portion of the cell laminate, and in this case, the cell is disposed with one electric double layer capacitor cell forming the negative electrode interposed therebetween. The terminals of the electric double layer capacitor cell forming the positive electrode are formed so as to sandwich the two separator side portions between the two separator side portions of the electric double layer capacitor cell forming the negative electrode. It is desirable to be electrically connected via a conductive conductor.
[0018]
Furthermore, the terminal forming the positive electrode and the terminal forming the negative electrode may be provided on opposite side surfaces of the cell stack.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
First, an example of a method for producing an electric double layer capacitor of the present invention is a schematic plan view and a diagram of FIG. 1 showing a production process of an electric double layer capacitor cell (hereinafter simply abbreviated as a cell) which is a part of the method. Description will be made based on the schematic sectional view of FIG.
First, a current collector 2 having a substantially rectangular terminal-forming conductor (hereinafter simply referred to as a conductor) 1 provided on one side is prepared, and polarizable electrodes 3 and 3 are formed on both sides of the current collector 2. Laminate (see step (a)).
[0020]
The polarizable electrode 3 preferably has a substantially rectangular shape, for example, a plate-like body having a thickness of 0.1 to 3 mm, particularly 0.15 to 1 mm, and includes activated carbon and a high specific surface area. Further, the polarizable electrode 3 is filled with an electrolyte solution described later.
[0021]
On the other hand, the conductor 1 and the current collector 2 are preferably made of a metal foil such as aluminum, tantalum, titanium, silver platinum, and gold having a thickness of 10 to 50 μm. Among them, the price, resistance value, workability, and durability are preferable. It is desirable that it is made of a metal foil mainly composed of aluminum.
[0022]
The conductor 1 is integrally formed on one side of the current collector 2, and specifically, for example, the metal foil is cut into a combined shape of the conductor 1 and the current collector 2 and formed as an integrated object. Alternatively, the conductor 1 and the current collector 2 can be formed as separate bodies and then joined between these end portions.
[0023]
Further, as shown in FIG. 3, the position where the conductor 1 of the current collector 2 is formed is (A) one formed on the entire side of the current collector 2, and (B) the side of the current collector 2. In addition to the structure of (C), (A), or (B), a conductor 1 is connected to the current collector 2 What formed the protrusion part 1a which protruded outside the top part of the edge | side in which the conductor 1 was formed is mentioned.
[0024]
In addition, according to the structure of (A), it can manufacture easily and can improve the intensity | strength and shape retention of the terminal 6 mentioned later, and in the structure of (B), it makes the cell 14a which makes the positive electrode mentioned later, and a negative electrode. When the cells 14b are alternately stacked, the terminals of adjacent cells can be formed so as not to contact each other. As a result, the positive electrode terminal and the negative electrode terminal can be formed on the same side surface of the stacked body. Further, according to the configuration of (C), the thickness of the terminal can be further increased by folding the protruding portion toward the current collector surface side, the strength of the terminal can be increased, and the thickness of the terminal forming portion of the cell can be increased. The cell can be stably stacked by approximating the thickness of the current collector portion of the cell.
[0025]
Next, the laminate of the current collector 2 and the polarizable electrodes 3 and 3 is divided into two separators so that a part of the conductor 1, specifically, a folded portion of the conductor 1 described later protrudes. 5 and 5 (see step (b)). At this time, the width of the conductor 1 accommodated in the separator 5 is equal to the width of the terminal 6, that is, the side of the laminate of the current collector 2 and the polarizable electrode 3 is equal to the height of the terminal 6. It is desirable to be disposed so as to be inward of the side.
[0026]
Specifically, electrolytic paper, polyethylene non-woven fabric, polypropylene non-woven fabric, polyester non-woven fabric, Teflon non-woven fabric, kraft paper, Manila hemp sheet, glass fiber sheet, etc. can be used as the separator 5, but the thickness of the separator 5 is 0.01 to It is desirable that the thickness is 0.1 mm, particularly 0.02 to 0.07 mm.
[0027]
Here, the positions of the polarizable electrodes 3 are such that the separators 5 and 5 are open at least between the sides from which the conductor 1 protrudes, and in particular, one side of the two separators 5 and 5 is contact-fixed. Desirable to prevent misalignment, specifically, a single layered body for forming a separator 5 is folded into two at the center, and at least one side of the two separators 5 and 5 is bonded The thing etc. which made the separator of 2 sheets the bag-like body are mentioned.
[0028]
In addition, the separator 5 is preferably one in which the side opposite to the side from which the conductor 1 protrudes is fixed in contact. In addition, according to FIG. 1, the separators 5 and 5 are opened between the side portions from which the conductor 1 protrudes, and the protruding portion 1a of the conductor 1 is opened, and the other separators 5, 5 is in the shape of a bag fixed in contact, and according to such a configuration, it is possible to further prevent displacement between the current collector 2, the polarizable electrode 3 and the separator 5.
[0029]
Next, after folding the part of the conductor 1 protruding from the separator 5 so as to sandwich one separator 5 (see step (c)), the folded part is folded in the opposite direction, and the side part of the other separator 5 is folded. , Sandwiching the sides of the separators 5 and 5 and overlapping and fixing them, and forming the terminal 6 made of at least four layers of the conductor 1 by bending the conductor 1 twice or more (step (d) )reference). The number of times of folding may be three or more, and the thickness of the terminal 6 can be controlled.
[0030]
At this time, in order to make the thickness of the terminal 6 uniform, the conductor 1 of the laminated body of the current collector 2 and the polarizable electrode 3 is formed on the side opposite to the side of the conductor 1 in contact with the current collector 2. It is desirable to fold it so that it matches the side that has been adjusted, and the fold line that is folded at the end of the conductor 1 is adjusted so as to coincide with the side portion of the separator 5 that is located on the conductor 1 forming side portion of the current collector 2. However, this is desirable in that the volume of the cell 14 is reduced to reduce the size of the multilayer electric double layer capacitor 20 described later.
[0031]
Here, the number of times of folding may be three times or more, and if desired, conductive portions such as a portion where the protruding portion 1a protruding outside the top of the side where the current collector 2 of the conductor 1 is formed are folded. The body 1 protruding portion 7 may be folded on the surface of the folding portion 8 of the conductor 1 located on the surface of the separator 5 with a crease therebetween. According to FIG. 1, the third folding is folded in a direction orthogonal to the first and second folding directions.
[0032]
Thereby, the thickness of the terminal 6 can be increased, the strength of the terminal 6 can be increased to further prevent the displacement of the polarizable electrode 3, and the thickness of the terminal 6 forming portion of the cell 14 can be reduced to the current collector in the cell 14. 2 and the thickness of the laminated body portion of the polarizable electrode 3 are preferably approximated to be the same, so that the cells can be stably laminated and the stress concentration on the terminal 6 of the cell 14 is partially reduced. No increase in internal resistance at the terminal 6 and at the interface between the terminal 6 and the current collector 2 can be prevented (see step (e)).
[0033]
Further, the conductor 1 protruding portion 7 such as a portion protruding from the side of the separator 5 before performing the final folding when the protruding portion 7 of the conductor 1 is folded three times or more is known such as ultrasonic welding or laser welding. The strength and rigidity of the conductor 1 protruding portion 7 and the terminal 6 can be increased by integrating by welding using the welding method.
[0034]
Further, if desired, the terminal 6 is a part of the side of the separator 5, particularly a width less than half of the side, that is, between the terminals 6 of the adjacent cells 14 in the stacked body of cells 14 in which the terminals are stacked on the same side. As for what is formed so as not to contact, two separators are formed in a region where the terminal 6 of the separator 5 is not in contact with the terminal 6, particularly in a portion which is line symmetric from the center of the side of the separator 5. A conductor 10 that sandwiches 5 and 5 is formed.
[0035]
The conductor 10 is preferably a clip made of a metal foil or a metal plate containing at least one selected from the group consisting of aluminum, tantalum, titanium, iron, cobalt, nickel, copper, silver, platinum, and gold. In the cell 14 laminated body in which the current collector 2 and the polarizable electrode 3 can be further reduced in positional deviation and the positive electrode and the negative electrode terminal 6 are formed on the same side surface, adjacent cells 14 and 14 with one cell interposed therebetween. By bringing the terminals 6 and 6 into contact with the conductor 10, respectively, the terminals 6 and 6 can be electrically connected. The thickness of the conductor 10 forming portion of the cell 14 is desirably the same as the thickness of the terminal 6 forming portion.
[0036]
Further, if desired, a through-hole 12 that penetrates the terminal 6 and the separator 5 and further a through-hole 12 that penetrates the conductor 10 and the separator 5 are formed to form an electric double layer capacitor cell (hereinafter simply referred to as a cell) 14. Can be manufactured (see FIG. 1F).
[0037]
The cell 14 is laminated in a plurality of layers so that the terminals 6 and 6 between the adjacent cells 14 do not contact each other, and two sets of the terminals 6 and 6 of every other cell 14 are electrically connected. The terminal groups are respectively a positive electrode terminal group and a negative electrode terminal group, and leads 15 are respectively connected to a part of these terminal groups.
[0038]
Further, after storing the laminate of the cells 14 in a sealing material 16 such as an aluminum laminate so that the leads 15 protrude outside, an electrolyte is injected into the polarizable electrode 3 and the separator 5 of the cells 14, The multilayer electric double layer capacitor 20 of the present invention can be manufactured by sealing the stacked body of the cells 14 with the leads 15 sandwiched therebetween.
[0039]
Examples of the electrolyte include aqueous solutions such as sulfuric acid and nitric acid, organic solvents such as propylene carbonate, γ-butyrolactone, N, N-dimethylformamide, ethylene carbonate, sulfolane, and 3-methylsulfolane, and quaternary ammonium salts, quaternary. Organic solutions in which electrolytes such as sulfonium salts and quaternary phosphonium salts are combined can be used.
[0040]
Further, as described above, for the cell 14 in which the through holes 12 and 12 are formed in the terminal 6 and the conductor 10, the through holes 12 and 12 of the cell 14 are respectively penetrated through the conductive rod-shaped body 18 and then laminated. It is possible to further prevent the positional deviation of the stacked body of the cells 14 by deforming both ends of the rod-shaped body 18 or screwing the cells 14 by screwing.
[0041]
Further, when the cell 14 having the terminals 6 formed thereon is stacked on the entire side of the current collector 2, the cells 6 may be stacked so that the terminals 6 of the positive cell 14a and the terminals 6 of the negative cell 14b face each other. Then, the conductor protrusions 7 are stacked in a protruding state, and the conductor protrusions 7 are bent so as to come into contact with the terminals 6 of the next cell 14 via the outer peripheral portion of the adjacent cell 14. Thus, the terminals 6 and 6 can be electrically connected.
[0042]
1 and 2 have the polarizable electrodes 3 and 3 laminated on both sides of the current collector 2, the present invention is not limited to this. For example, the cell 14 is laminated. As for the cell located at the laminated end of the body, the polarizable electrode 3 may be formed on one side of the current collector 2.
[0043]
(Configuration of electric double layer capacitor)
FIG. 4 shows a schematic cross-sectional view of an example of the multilayer electric double layer capacitor of the present invention obtained by the method described above.
According to FIG. 4, the multilayer electric double layer capacitor 20 has a configuration in which a plurality of cells 14 are stacked, and the stacked body of the cells 14 is housed and sealed in a sealing material 16. The cell 14 is formed by alternately laminating a cell forming a positive electrode (hereinafter simply referred to as a positive electrode cell) 14a and a cell forming a negative electrode (hereinafter simply referred to as a negative electrode cell) 14b.
[0044]
The cell 14 houses a substantially rectangular current collector 2 in which substantially rectangular polarizable electrodes 3 and 3 are laminated on both surfaces in two separators 5. Comprises the conductor 1 connected to the two sides of the current collector a plurality of times to form a multi-layered conductor 1 and a terminal 6 with two sides of the separator 5 interposed therebetween. Has been.
[0045]
Here, according to FIG. 4, the two separators 5 and 5 are contacted and fixed to each other at the side portion of the separator 5 opposite to the side where the terminals 6 are formed, and preferably the separator 5 The side portions other than the side portions on which the terminals 5 and 5 are formed are fixed in contact with each other.
[0046]
Moreover, according to FIG. 4, the terminal 6 of the positive electrode cell 14a is formed only in a part of the side part of the separator 5, and it does not contact the terminal (not shown) of the adjacent negative electrode cell 14b. Is formed. Furthermore, according to FIG. 4, between the terminals 6 and 6 that face each other with the negative electrode cell 14b interposed therebetween, the conductors 10 provided so as to sandwich the separators 5 and 5 of the negative electrode cell 14b are electrically connected. It is connected.
[0047]
In addition, according to FIG. 4, the lead 15 connected to the terminal 6 of the positive electrode cell 14a or a part of the conductor 10 is disposed substantially parallel to the cell 14 at the center of the cell 14 laminate, and the lead 15 is sealed. Projecting to the outside of the stopper 16. Although not shown, the lead 15 is similarly formed for the negative electrode cell 14b. Then, the electric double layer capacitor 20 can be connected to the external circuit (not shown) by connecting the two leads 15 protruding outside the sealing material 16 to the terminals (not shown) of the external circuit as the extraction electrodes. it can.
[0048]
Further, according to FIG. 4, a through hole 12 that penetrates each of the terminal 6 and the conductor 10 is formed, and a conductive rod-like body 18 made of a metal such as a rivet or a bolt is disposed in the through hole 12. . This facilitates positioning when the cells 14 are stacked, prevents positional displacement between the cells 14 and 14, allows reliable connection between the plurality of terminals 6 and the conductors 10, and has an internal resistance value. Can be reduced.
[0049]
Although not shown, the conductor 10, the lead 15, the through hole 12, and the conductive rod 18 are also formed on the negative electrode cell side and are electrically connected in the same manner as the positive electrode cell.
[0050]
Further, the cell 14 located at the stacking end in the stack of cells 14 in FIG. 4 has the same configuration as the cell inside the cell 14 stack, but the present invention is not limited to this, and the end As for the cell 14, the polarizable electrode 3 may be formed on one surface of the current collector 2, and the end cell 14 may be one in which the current collector is in direct contact with the separator on the side of the laminated end.
[0051]
【The invention's effect】
As described above in detail, according to the multilayer electric double layer capacitor of the present invention, the current collector and the polarizable electrode are accommodated between two separators, and a part of the current collector has a side portion. Is provided with a terminal-forming conductor protruding from the opening of the separator, and the terminal-forming conductor is folded a plurality of times so as to sandwich the side of the separator to form a terminal. Since the sides of the separator can be sandwiched and overlapped and fixed, the positional deviation between the current collector-polarizable electrode-separator in the cell is reduced, and a terminal is provided on the side of the separator, and Since thick terminals can be formed, high electrostatic capacity and low internal resistance can be achieved at the same time, which can enhance the strength and shape retention of the terminals, and the position due to partial thickness differences of cells during cell stacking Slip You can stop, the productivity is improved.
[Brief description of the drawings]
FIG. 1 is a schematic plan view for explaining a partial process of an example of a method for producing an electric double layer capacitor of the present invention.
FIG. 2 is a schematic cross-sectional view of FIG.
FIG. 3 is a schematic diagram for explaining an example of forming a conductor and a current collector in an example of a method for producing an electric double layer capacitor of the present invention.
FIG. 4 is a schematic cross-sectional view of an example of the electric double layer capacitor of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Terminal formation conductor 1a Overhang | projection part 2 Current collector 3 Polarization electrode 5 Separator 6 Terminal 7 Conductor protrusion part 8 Bending part 10 Conductor 12 Through-hole 14 Electric double layer capacitor cell 15 Lead 16 Sealing material 18 Conductivity Rod-shaped body 20 Multilayer type electric double layer capacitor

Claims

A substantially rectangular laminate in which a polarizable electrode is laminated on at least one surface of a current collector is housed between two roughly rectangular separators, and terminals are formed on at least a part of the current collector side portion. And a plurality of electric double layer capacitor cells formed by folding the terminal-forming conductive layer so as to sandwich the end portions of the two separators to form terminals. Characteristic multilayer electric double layer capacitor.

2. The multilayer electric double layer capacitor according to claim 1, wherein the two separators are bag-like bodies.

The multilayer electric double layer capacitor according to claim 1 or 2, wherein the folded portions of the terminal-forming conductor are partially welded.

2. The thickness of the portion of the electric double layer capacitor cell that houses the current collector and polarizable electrode stack is the same as the thickness of the portion of the cell where the terminal is formed. 4. The multilayer electric double layer capacitor according to any one of items 1 to 3.

The electric double layer capacitor cells forming the plurality of positive electrodes and negative electrodes formed with the terminals forming the positive and negative electrodes are alternately stacked so that the terminals forming the positive and negative electrodes are not in contact with each other, and forming the positive electrode 5. The multilayer electric double layer capacitor according to claim 1, wherein the terminals and the terminals forming the negative electrode are electrically connected to each other.

Forming a through hole penetrating the terminal and separator of the electric double layer capacitor cell forming a plurality of the positive and negative electrodes, and penetrating two conductive rods forming the positive electrode and the negative electrode in the through hole, 6. The multilayer electric double layer capacitor according to claim 5, wherein the electric double layer capacitor cell is laminated and fixed.

7. The multilayer electric double layer capacitor according to claim 5, wherein the terminals forming the positive electrode and the negative electrode are provided on the same side surface portion of the cell laminate.

The terminals of the electric double layer capacitor cell forming the positive electrode, which are arranged with one electric double layer capacitor cell forming the negative electrode interposed therebetween, are connected to the two electric double layer capacitor cell forming the negative electrode. 8. The stacked electric device according to claim 5, wherein the separator is electrically connected to a separator side portion through a conductor formed so as to sandwich the two separator side portions. Double layer capacitor.

7. The multilayer electric double layer capacitor according to claim 5, wherein the positive electrode terminal and the negative electrode terminal are provided on opposite side surfaces of the cell laminate.