JP4066763B2

JP4066763B2 - Bipolar battery, manufacturing method thereof, and vehicle

Info

Publication number: JP4066763B2
Application number: JP2002286274A
Authority: JP
Inventors: 康彦大澤; 達弘福沢
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2002-09-30
Filing date: 2002-09-30
Publication date: 2008-03-26
Anticipated expiration: 2022-09-30
Also published as: JP2004127559A

Description

【０００１】
【発明の属する技術分野】
本発明は、正極活物質と負極活物質とが集電体の両側に配置されてなるバイポーラー電池に関し、より詳しくは、実質的に溶液を含まない高分子固体電解質を電解質として用いてなるバイポーラー電池とその製造方法並びに車両に関する。
【０００２】
【従来の技術】
近年、電気自動車等の大容量電源として、高エネルギー密度、高出力密度が達成できるリチウムイオン二次電池が開発され使用されている。リチウムイオン二次電池の基本構成は、アルミニウム集電体にコバルト酸リチウム等の正極活物質とアセチレンブラック等の導電助剤をバインダーを用いて塗布した正極と、銅集電体にカーボン微粒子をバインダーを用いて塗布した負極を、ポリオレフィン系の多孔質膜セパレーターを介して配置し、これにＬｉＰＦ₆等を含む非水電解液を満たしている。
【０００３】
リチウムイオン二次電池を電気自動車等の電源として使用する場合は、大出力を確保するために、複数の二次電池を直列に接続して用いる必要がある。前記基本構成の単電池（セル）を直列接続した電池モジュール単位、更にこの電池モジュール単位を直列接続して組電池として用いる。
【０００４】
しかし、接続部を介して電池を接続した場合、接続部の電気抵抗によって出力が低下することになる。また、接続部を有する電池は空間的にも不利益を有する。即ち、接続部の占有体積によって、電池の出力密度やエネルギー密度が低下する。
【０００５】
この問題を解決するものとして、セル間接続の抵抗を低減し、コンパクト化したバイポーラー電池が提案されている（例えば、特許文献１参照。）。
【０００６】
このバイポーラー電池では、集電体として２種類の金属箔を圧延加工した、いわゆるクラッド材を使用し、電解質に液体を用いているので、各セルでの密閉シールが不可欠であり、セル間で液絡が起こる可能性がある。そこで、この電解液のかわりに、高分子固体電解質を用いると、密閉シールが不要となり現実的なバイポーラー電池とすることができる。
【０００７】
このような構造を有する例として、導電性基板の一面に正極活物質層を、他面に負極活物質層を配置してバイポーラー電極を構成し、この電極を高分子固体電解質層を介して複数積層した構造のバイポーラー電池、つまり、正極活物質６、固体電解質４、負極活物質７、導電性基板本体５を複数個積層したバイポーラー電池も提案されている（例えば、特許文献２参照。）。
【０００８】
このバイポーラー電池は、活物質の利用率を高めるために、導電性基板、正極活物質層、負極活物質層、電解質層をきわめて薄肉としている。例えば、導電性基板が０．５μｍ、正極活物質層が１μｍ、負極活物質層が１．５μｍ、電解質層が１μｍ程度としている。
【０００９】
【特許文献１】
特開平８−７９２６号公報（段落「０００７」〜「０００９」、図１〜２）
【特許文献２】
実開平４−５４１４８号公報（第２図）
【００１０】
【発明が解決しようとする課題】
しかし、このような薄肉の部材を、相互の密着性を確保しながら積層することは、作業性がきわめて面倒である。特に、固体電解質はゲル電解質と比べると、イオン伝導度が低く、しかも、電極層と高分子固体電解質層との間が十分に密着性が保持されないと、さらにイオン伝導性が低下し、この層間部分で抵抗が増大する虞もある。
【００１１】
この密着を確保するためには、例えば、積層部材をケース等に入れ、弾性体により当該積層部材に圧力を掛けることもできるが、薄肉のものが多数積層されたものに対し全面に渡り均一に圧力を掛けることは、面倒であり困難でもある。また、前記電解質層又は電極層のいずれかが粘着性を有していれば、前記密着性は向上するが、このようにしても長期にわたって密着性を保持するには、やはり何らかの方法で圧力を掛け続ける必要がある。
【００１２】
本発明は、これらの問題点に鑑み、成形された積層部材に対し圧力を加える手段を別途設けなくても、電極層や電解質層間での密着性を保持することができるバイポーラー電池を提供することを第１の目的とする。
【００１３】
本発明の第２の目的は、同バイポーラー電池の製造方法を提供することにある。
【００１４】
本発明の第３の目的は、同バイポーラー電池を搭載した車両を提供することにある。
【００１５】
【課題を解決するための手段】
本発明の目的は、下記する手段により達成される。
【００１６】
（１）集電体の一面に正極活物質層を他面に負極活物質層を有するバイポーラー電極に高分子固体電解質層を設けた単位積層電極を積層してなるバイポーラー電池において、円弧状若しくは円環状であり、その表面に凹部が設けられた芯材と、所定の幅と長さを有する前記単位積層電極を少なくとも２層以上積層して、その一端部が前記凹部に挿入されて前記芯材に巻き回されて、曲率を持つ断面形状となる積層部材と、を有することを特徴とするバイポーラー電池。
（２）集電体の一面に正極活物質層を他面に負極活物質層を有するバイポーラー電極に高分子固体電解質層を設けた単位積層電極を積層してなるバイポーラー電池において、
円弧状若しくは円環状の芯材と、
所定の幅と長さを有する前記単位積層電極を少なくとも２層以上積層して、前記芯材に巻き回されて、曲率を持つ断面形状となる積層部材と、
前記積層部材の巻回開始端部とその外周の巻回層との間に設けられた挿入物と、を有することを特徴とするバイポーラー電池。
【００１７】
（３）前記積層部材は、重ね合わした各積層部材相互間に、電気的導通を阻止する絶縁層を設けたことを特徴とする前記（１）又は（２）のバイポーラー電池。
【００１８】
（４）前記積層部材は、前記曲率を持つ断面形状を保持する保持手段を設けたことを特徴とする前記（１）〜（３）のバイポーラー電池。
【００２０】
（５）前記積層部材は、最外部に位置する層の外周面と、最内部に位置する層の内周面に、他の集電体よりも厚肉の端部集電体を設けたことを特徴とする前記(1)〜(4)のバイポーラー電池。
【００２１】
（６）前記曲率を持つ断面形状とされた積層部材の内部空間に発熱体を設けたことを特徴とする前記(1)〜(5)のバイポーラー電池。
【００２２】
（７）集電体の一面に正極活物質層を他面に負極活物質層を有するバイポーラー電極に高分子固体電解質層を設けた単位積層電極を積層してなるバイポーラー電池の製造方法において、円弧状若しくは円環状をし、外周面に凹部が形成された芯材に、所定の幅と長さの前記単位積層電極が少なくとも２層以上積層された積層部材を、前記凹部にその一端部を入れて前記心材の外周面に密に巻回することを特徴とするバイポーラー電池の製造方法。
（８）集電体の一面に正極活物質層を他面に負極活物質層を有するバイポーラー電極に高分子固体電解質層を設けた単位積層電極を積層してなるバイポーラー電池の製造方法において、所定の幅と長さの前記単位積層電極が少なくとも２層以上積層された積層部材を、円弧状若しくは円環状をした芯材の外周面に、巻回開始端部とその外周の巻回層との間に挿入物を入れて、密に巻回することを特徴とするバイポーラー電池の製造方法。
【００２３】
（９）前記積層部材は、重なり合った各層間に、電気的導通を阻止する絶縁層を設けたことを特徴とする前記（７）又は（８）のバイポーラー電池の製造方法。
【００２４】
（１０）前記積層部材は、前記曲率を持つ形状を保持する保持手段を設けたことを特徴とする前記（７）〜（９）のバイポーラー電池の製造方法。
【００２５】
（１１）前記積層部材は、複数枚の単位積層電極を環状に成形するときの各単位積層電極の始端が同位置で重合状態となるようにしたことを特徴とする前記（７）〜（１０）のバイポーラー電池の製造方法。
【００２６】
（１２）前記単位積層電極は、始端位置調節する絶縁性の始端位置調節部材を有することを特徴とする前記（１１）のバイポーラー電池の製造方法。
【００２７】
（１３）前記積層部材は、前記単位積層電極を重ね合わした複数層の束全体を絶縁性フィルムにより覆いシールしたものを前記芯材の外周面に巻回したことを特徴とする前記（７）〜（１２）のバイポーラー電池の製造方法。
【００２９】
（１４）前記段差防止手段は、前記芯材の外周面に形成した凹部である前記(13)のバイポーラー電池の製造方法。
【００３１】
（１４）（１）〜（６）のバイポーラー電池を１つ又は複数接続して電源としたことを特徴とする車両。
【００３２】
【発明の効果】
請求項１及び２の発明は、積層部材が曲率を持つ断面形状としたので、積層部材を構成する単位積層電極は、成形された積層部材に対し圧力を加える手段を別途設けなくても、その形状から各単位積層電極相互間での電極層や電解質層間での密着性を保持することができ、イオン伝導性の低下や内部抵抗の増大が防止された高性能のバイポーラー電池となる。また、曲率を持つ断面形状を巻回することにより形成すれば、その巻回量あるいは巻回長さにより電池の容量も調節することができ、さらに、巻回した積層部材の内部から芯材を除去すれば、形状的にも自由な形状設定が可能となる。そして、芯材に、積層部材の巻回開始端部とその外周の巻回層との間で段差が生じないようにする段差防止手段として、心材に小部を設けたり、または挿入物を入れたことで、この段差部分で生じやすい短絡を確実に防止できる。
【００３３】
請求項３の発明は、重ね合わした各積層部材相互間に、電気的導通を阻止する絶縁層を設けたので、各層の重なりによる短絡が防止され、より安全性の高いバイポーラー電池となる。
【００３４】
請求項４の発明は、曲率を持つ積層部材の断面形状を保持手段により保持すれば、イオン伝導性の低下や内部抵抗の増大が防止されたバイポーラー電池の性能を高い状態で維持できる。
【００３６】
請求項５の発明は、最外部と最内部に、他の集電体よりも厚肉の端部集電体を設けたので、バイポーラー電池の電流の流れから集電体の面方向の抵抗を低減でき、電池各部でのインピーダンスを同程度にすることができる。
【００３７】
請求項６の発明は、積層部材の内部空間に発熱体を設けたので、高分子固体電解質層を活性化でき、電流の流れを円滑にし、電池の性能を高めることができる。
【００３８】
請求項７および８の発明は、単位積層電極が少なくとも２層以上積層された積層部材を、円弧状若しくは円環状をした芯材の外周面に密に巻回したので、薄肉の単位積層電極でも曲率のある積層部材を簡単に形成でき、バイポーラー電池の製造が極めて容易となる。しかも、芯材に、積層部材の巻回開始端部とその外周の巻回層との間で段差が生じないように段差防止手段として凹部または挿入物を設けて巻き回すこととしたので、この段差部分で生じやすい短絡を確実に防止できる。
【００３９】
請求項９の発明は、積層部材の重なり合った各層間に、電気的導通を阻止する絶縁層を設ければ、各層の重なりによる短絡が防止され、より安全性の高いバイポーラー電池を極めて容易に製造できる。
【００４０】
請求項１０の発明は、曲率を持つ積層部材の断面形状を保持手段により保持すれば、イオン伝導性の低下や内部抵抗の増大が防止された高性能のバイポーラー電池を極めて容易に製造できる。
【００４１】
請求項１１の発明は、複数枚の単位積層電極の始端が同位置で重合状態となるように、芯材の外周面に密に巻回すれば、薄肉の材料でも簡単に積層部材を形成でき、また、巻回された各層相互間での密着性も向上する。
【００４２】
請求項１２の発明は、各単位積層電極に絶縁性の始端位置調節部材を設ければ、巻回された各層相互間で段差がなく、スムーズに巻回でき、密着性も向上する。
【００４３】
請求項１３の発明は、単位積層電極を重ね合わした複数層の束全体を絶縁性フィルムにより覆いシールしたものを芯材の外周面に巻回すれば、積層部材の取り扱いや巻回作業が容易で、作業性が向上する。特にヒートシーラによりヒートシールすれば、巻き付けがさらに簡単にできる。
【００４５】
請求項１４の発明は、小型、軽量で、成形性が良く、形状的にも厳密に特定されないバイポーラー電池を、電気自動車、ハイブリッド電気自動車、燃料電池車、内燃機関自動車等の車両に搭載すれば、スペース的にも車両の性能面でも有効な電源として使用でき、省エネルギとなり、環境衛生面で寄与するところ大である。
【００４６】
【発明の実施の形態】
以下、本発明の実施形態を添付図面に基づいて説明する。
【００４７】
図１は本発明の実施形態の一部破断概略斜視図、図２は単位積層電極等の平面図、図３は図２の３−３線に沿う断面図である。
【００４８】
図１において、本実施形態のバイポーラー電池について概説すれば、基本的には、単位積層電極１を２層以上積層した積層部材Ｓを円筒状の芯材２の周りに巻きつけ、断面形状が曲率を持つようにしている。
【００４９】
なお、本明細書においては、単位積層電極１とは、図２，３に示すように、集電体３の一面に正極活物質層４を他面に負極活物質層５を保持したバイポーラー電極Ｐに高分子固体電解質層６を積層したものをいい、積層部材Ｓは、この単位積層電極を少なくとも２層以上積層したものをいう。
【００５０】
このように積層部材Ｓを、曲面を有する芯材２の周りに巻回すると、芯材２の周囲に形成された積層部材Ｓの各層は、軸直角断面形状が曲率を持つ形状となる。この結果、積層部材Ｓは、圧力を加えなくても、各単位積層電極１相互間での密着性を保持でき、イオン伝導性の低下や内部抵抗の増大が防止される。
【００５１】
図４は図１の４−４線に沿う断面相当図であるが、本図では複数枚の単位積層電極１が積層された積層部材Ｓを１本の線として示しており、図５は図４の５−５線に沿う概略断面図で、主として１つの積層部材Ｓのみを詳示している。
【００５２】
このバイポーラー電池は、基本的には、図２に示すように、所定の幅Ｗと長さＬを有する短冊状の単位積層電極１を多数作製し、所定の方法で少なくとも２層以上積層して積層部材Ｓを形成する。なお、積層方法は、単に積み重ねても良いが、後に詳述する手法を用いても良い。そして、図４に示すように、この積層部材Ｓを円筒状の芯材２の周りに巻回し、長さ方向断面形状が曲率を持つ形状とするが、この形状を保持するため、テープあるいは接着剤などの適当な保持手段７により保持している。
【００５３】
積層部材Ｓが曲率を持つ断面形状となるように巻回すれば、その巻回量あるいは巻回長さにより電池の容量も調節することができ、場合によっては、巻回した積層部材Ｓの内部から芯材を除去すれば、全体形状が変形自在となり、形状的にも自由な形状設定が可能となる。
【００５４】
ただし、積層部材Ｓを芯材２の周りに重積するように巻回すると、各層間で電気的に導通する虞があるので、各層間には絶縁層８（図４では破線で示す）を設けることが好ましい。この絶縁層８は、巻回された単位積層電極１の層が隣位の層に接触しないように絶縁するものである。なお、使用する絶縁層８としては、カプトン粘着フィルム、ポリエステル粘着フィルム、ポリオレフィン粘着フィルム等がある。
【００５５】
バイポーラー電池では、電流は、図５の矢印で示すように、正極活物質層４から負極活物質層５に向かって、高分子固体電解質層６を通って流れる特性がある。つまり、積層部材Ｓを貫通するように流れるので、巻回した積層部材Ｓは、積層部材Ｓの最外部と最内部に位置する端部集電体９の肉厚Ｔを、他の集電体３の肉厚ｔよりも厚肉とすることが好ましい。このようにすれば、端部集電体９の面方向に流れる電流の抵抗を低減でき、電池各部でのインピーダンスを同程度にすることができる。
【００５６】
前記積層部材Ｓは、全体をラミネートフィルムのような絶縁性フィルム１０で覆っても良い。このようにすると、バイポーラー電池から不必要に漏電することはなく、効率よく電流を取り出すことができ、電池も長寿命となり、好ましい。
【００５７】
また、芯材２の内部空間Ｍに発熱体（不図示）を設けると、発熱体の熱で高分子固体電解質層を活性化でき、電流の流れを円滑にし、電池の性能を高めることができる。なお、発熱体としては、電池を使用する対象物により異なるが、例えば、エンジンとモータを持ったハイブリッドカーでは、エンジンマフラーなどが考えられる。
【００５８】
さらに、前記単位積層電極１の構成要素を個別に説明し、電池の製法について述べる。
【００５９】
＜集電体＞
集電体３は、その表面材質がアルミニウムである。表面材質がアルミニウムであると、形成される活物質層が高分子固体電解質を含む場合であっても、高い機械的強度を有する活物質層となる。集電体３は、表面材質がアルミニウムであれば、その構成については特に限定されない。集電体３がアルミニウムそのものであってもよい。また、集電体３の表面がアルミニウムで被覆されている形態であってもよい。つまり、アルミニウム以外の物質（銅、チタン、ニッケル、ＳＵＳ、これらの合金など）の表面に、アルミニウムを被覆させた集電体であってもよい。場合によっては、２以上の板を張り合わせた集電体を用いてもよい。耐蝕性、作り易さ、経済性などの観点からは、アルミニウム箔単体を集電体として用いることが好ましい。
【００６０】
＜正極活物質層＞
正極活物質層は、正極活物質、高分子固体電解質を含む。この他にも、イオン伝導性を高めるためにリチウム塩、電子伝導性を高めるために導電助剤などが含まれ得る。
【００６１】
正極活物質としては、溶液系のリチウムイオン電池でも使用される、遷移金属とリチウムとの複合酸化物を使用できる。具体的には、ＬｉＣｏＯ₂などのＬｉ・Ｃｏ系複合酸化物、ＬｉＮｉＯ₂などのＬｉ・Ｎｉ系複合酸化物、スピネルＬｉＭｎ₂Ｏ₄などのＬｉ・Ｍｎ系複合酸化物、ＬｉＦｅＯ₂などのＬｉ・Ｆｅ系複合酸化物などが挙げられる。この他、ＬｉＦｅＰＯ₄などの遷移金属とリチウムのリン酸化合物や硫酸化合物；Ｖ₂Ｏ₅、ＭｎＯ₂、ＴｉＳ₂、ＭｏＳ₂、ＭｏＯ₃などの遷移金属酸化物や硫化物；ＰｂＯ₂、ＡｇＯ、ＮｉＯＯＨなどが挙げられる。
【００６２】
正極活物質の粒径は、バイポーラー電池の電極抵抗を低減するために、電解質が固体でない溶液タイプのリチウムイオン電池で一般に用いられる粒径よりも小さいものを使用するとよい。
【００６３】
＜高分子固体電解質＞
高分子固体電解質は、イオン伝導性を有する高分子であれば、特に限定されるものではない。イオン伝導性を有する高分子としては、ポリエチレンオキシド（ＰＥＯ）、ポリプロピレンオキシド（ＰＰＯ）、これらの共重合体などが挙げられる。かようなポリアルキレンオキシド系高分子は、ＬｉＢＦ₄、ＬｉＰＦ₆、ＬｉＮ（ＳＯ₂ＣＦ₃）₂、ＬｉＮ（ＳＯ₂Ｃ₂Ｆ₅）₂などのリチウム塩をよく溶解しうる。また、架橋構造を形成することによって優れた機械的強度が発現する。
【００６４】
本発明において高分子固体電解質は、正極活物質層または負極活物質層の少なくとも一方に含まれる。ただし、バイポーラー電池の電池特性をより向上させるためには、双方に含まれることが好適である。
【００６５】
リチウム塩としては、ＬｉＢＦ₄、ＬｉＰＦ₆、ＬｉＮ（ＳＯ₂ＣＦ₃）₂、ＬｉＮ（ＳＯ₂Ｃ₂Ｆ₅）₂、またはこれらの混合物などが使用できる。ただし、これらに限られるわけではない。
【００６６】
導電助剤としては、アセチレンブラック、カーボンブラック、グラファイト等が挙げられる。ただし、これらに限られるわけではない。
【００６７】
＜負極活物質層＞
負極活物質層は、負極活物質、高分子固体電解質を含む。この他にも、イオン伝導性を高めるためにリチウム塩、電子伝導性を高めるために導電助剤などが含まれ得る。負極活物質の種類以外は、基本的に「正極活物質」の項で記載した内容と同様であるため、ここでは説明を省略する。
【００６８】
負極活物質としては、溶液系のリチウムイオン電池でも使用される負極活物質を用いることができる。ただし、本発明のバイポーラー電池は高分子固体電解質が用いられるため、高分子固体電解質での反応性を考慮すると、金属酸化物または金属とリチウムとの複合酸化物が好ましい。より好ましくは、負極活物質は遷移金属酸化物または遷移金属とリチウムとの複合酸化物である。さらに好ましくは、前記遷移金属はチタンである。つまり、負極活物質は、チタン酸化物またはチタンとリチウムとの複合酸化物であることがさらに好ましい。
【００６９】
＜高分子固体電解質層＞
高分子固体電解質層は、イオン伝導性を有する高分子から構成される層であり、イオン伝導性を示すのであれば材料は限定されない。高分子固体電解質としては、ポリエチレンオキシド（ＰＥＯ）、ポリプロピレンオキシド（ＰＰＯ）、これらの共重合体系高分子で、分子内に架橋性の炭素―炭素の二重結合を持った原料高分子を用いてラジカル重合法で合成した高分子固体電解質が挙げられる。
【００７０】
高分子固体電解質層中には、イオン伝導性を確保するためにリチウム塩が含まれる。リチウム塩としては、ＬｉＢＦ₄、ＬｉＰＦ₆、ＬｉＮ（ＳＯ₂ＣＦ₃）₂、ＬｉＮ（ＳＯ₂Ｃ₂Ｆ₅）₂、またはこれらの混合物などが使用できる。ただし、これらに限られるわけではない。ＰＥＯ、ＰＰＯのようなポリアルキレンオキシド系高分子は、ＬｉＢＦ₄、ＬｉＰＦ₆、ＬｉＮ（ＳＯ₂ＣＦ₃）₂、ＬｉＮ（ＳＯ₂Ｃ₂Ｆ₅）₂などのリチウム塩をよく溶解しうる。また、架橋構造を形成することによって、優れた機械的強度が発現する。
【００７１】
高分子電解質膜は、前記と同様例えばポリエチレンオキシド（ＰＥＯ）、ポリプロピレンオキシド（ＰＰＯ）及びそれらの共重合体系高分子で、分子内に架橋性の炭素―炭素の二重結合を持った原料高分子とリチウム塩をＮＭＰのような溶媒に溶解させてスペサーで厚さを決めた光透過性のギャップに流し込み紫外線を照射して架橋させて薄膜を作製できるが、この方法に限られるわけではない。放射線重合、電子線重合、熱重合法によっても高分子電解質膜を作製できる。紫外線重合の場合には適当な光重合開始剤を用い、熱重合法の場合にも熱重合開始剤を用いてもよい。溶解させるリチウム塩としては、ＬｉＢＦ₄、ＬｉＰＦ₆、ＬｉＮ（ＳＯ₂ＣＦ₃）₂、ＬｉＮ（ＳＯ₂Ｃ₂Ｆ₅）₂及びこれらの２種以上の混合物等を使用できるが、これらに限られるわけではない。
【００７２】
＜単位積層電極の作製＞
本実施形態に係る単位積層電極１を構成するためには、まず、上記した負極活物質層５における原料高分子と、負極活物質、導電助材、リチウム塩、溶媒と少量のアゾビスイソブチロニトリル（ＡＩＢＮ）等の熱重合開始剤からスラリーを調製し、これを集電体３の一面に塗布して加熱して負極活物質層５を作製する。
【００７３】
次に、正極活物質層４をこの集電体３の他面に同様にして形成することによりバイポーラー電極Ｐを作製する。なお、この正極活物質層４と負極活物質層５の形成の順序は逆でもよい。
【００７４】
このバイポーラー電極Ｐの上に高分子固体電解質層６を形成する。この形成に当っては、リチウム塩と原料高分子と紫外線重合開始剤を含む溶液を単位積層電極１上に直接塗布して、ＰＥＴ等の透明フィルムをかぶせて、１０分間から２０分間紫外線照射することによって単位積層電極１が形成できる。
【００７５】
この結果、図３に示すように、下から高分子固体電解質層６、負極活物質層５、集電体３、正極活物質層４の順で層状に形成された単位積層電極１が形成される。
【００７６】
なお、集電体３の両側に絶縁層（一点鎖線で示す）を設け、各単位積層電極１相互間を絶縁しても良い。
【００７７】
＜バイポーラー電池の製造方法＞
本製造方法の第１の実施形態は、複数枚の単位積層電極１を１枚ずつ芯材２の周囲に巻回することにより積層し、積層部材Ｓを形成するバイポーラー電池の製造方法である。
【００７８】
ここで使用する芯材２としては、曲率をもったものであればどのようなものであっても良い。例えば、単に円弧状のものあるいは筒状楕円、円環状等でもよいが、特に、巻きつけ圧力がより均一にかかるものであって、かつ軽量なものとしては、軸方向に前記積層部材Ｓの幅、つまり各単位積層電極１の幅Ｗと同程度の長さを有し、アルミニウムからなる軸直角断面が円弧状若しくは円環状をしたものが好ましい。ただし、電池の効率を高めるために、芯材２の外周面は絶縁層（不図示）で覆うことが好ましい。
【００７９】
図６は本発明に係る製造方法の第１の実施形態の要部を示す概略説明図である。この芯材２を使用してバイポーラー電池を製造する場合は、図６において、まず、芯材２の軸線が直立に立設するように、モータなどの回転軸に取り付ける。
【００８０】
本実施形態では、芯材２の周囲に５枚の単位積層電極１ａ〜１ｅと、最外部及び最内部の端部集電体９、９と、絶縁層８とを配置する。
【００８１】
なお、芯材２の周りには、単位積層電極１を供給するローラ（不図示）を複数配置し、単位積層電極１の両端に位置する単位積層電極１ａと１ｅとの間には、端部集電体９や絶縁層８を供給するローラも配置し、これらローラにより単位積層電極１等を供給しつつ巻回作業を行なう。
【００８２】
巻回作業は、まず第１番目の単位積層電極１ａを芯材２の周囲に巻き付けた後に、第２番目の単位積層電極１ｂの始端が第１番目の単位積層電極１ａの始端と一致するように重ね、各単位積層電極１に張力をかけつつ、芯材２に巻き取る。以下同様に各単位積層電極１ｃ〜１ｅを、始端及び終端が一致するように巻回する。
【００８３】
この場合、各単位積層電極１の始端部分に絶縁性の粘着フィルム等のような始端調節部材１１（図２参照）を設けておき、長さを調節し、巻き付け用の芯材２の適当な位置から順次貼り付けると、始端を一致させて層状に巻回したときにも、この始端で段差が生じることがなく、スムーズな巻回が可能となる。しかも、このようにすれば、段差部分で生じやすい短絡も確実に防止でき、巻回された各層相互間での密着性が向上し、イオン伝導性の低下や内部抵抗の増大が防止される。
【００８４】
このようにして積層部材Ｓが形成されると、保持手段７により当該曲率を有する形状を保持し、最外部を絶縁性フィルム１０で覆うと共に端部集電体９に接続されたリード線１２（図１，４参照）を突出させる。
【００８５】
このバイポーラー電池では、電流は、各積層部材Ｓ内では、いわば各単位積層電極１を貫通して流れるが、ここでは、単位積層電極１相互間が密に当接された状態となるので、イオン伝導性の低下や内部抵抗の増大が防止され、高性能のバイポーラー電池となる。
【００８６】
なお、前記電流は、端部集電体９に至ると当該端部集電体９の面、つまり周方向に沿って流れ、リード線１２を通って外部に導かれる。
【００８７】
次に、本製造方法の第２の実施形態について述べる。
【００８８】
図７は第２の実施形態で使用する複数の単位積層電極を積み重ねた積層部材の断面図、図８，９は段差防止手段を示す断面図である。
【００８９】
第２の実施形態は、所定の幅Ｗと長さを有する単位積層電極１を、予め複数枚積み重ね、この積み重ねた束を積層部材Ｓとして用い、前記芯材２の外周面に密に巻回するようにしている。前述の場合と同様の芯材２を使用するが、この芯材２の外周面に予め複数枚積層した単位積層電極１を巻回すれば、多数の単位積層電極１を芯材２の周囲に個々に巻回する場合に比し、一括して巻回でき、巻回作業性が向上する。
【００９０】
この場合、積層部材Ｓとしては、長さ１ｍ程度のものを使用しているが、芯材２の周囲に巻回した場合、１巻き目と２巻き目との間に段差が生じ、この段差部分で短絡が生じる虞があることから、本実施形態では、段差防止手段１５を設けることが好ましい。
【００９１】
この段差防止手段１５は、段差を解消できるものであればどのようなものでも良いが、本実施形態では、図８に示すように、前記芯材２の外周面に凹部１５ａを形成することにより段差防止手段としている。このような凹部１５ａを形成すれば、１巻き目の始端部がここに入り込むことになり、２巻き目が巻かれても両者間に段差の発生が防止される。
【００９２】
特に、このような凹部１５ａを設けると、積層部材Ｓの巻きつけがスムーズにかつ素早くでき、作業性が向上するのみでなく、巻回時の締め付けも防止される。段差部分を有するものの外周に次位の層を巻きつけると、この巻き締めにより１巻き目の始端部は強力に加圧され締め付けられることになり、内部の各単位積層電極１相互間等で短絡が発生しやすいが、前記凹部１５ａの形成により、このような短絡が確実に防止できる。
【００９３】
また、図９に示すような他の段差防止手段でもよい。図示のものは、ゴムなどにより構成された、いわば枕状部材１５ｂを前記段差部分に挿入したものであるが、このような絶縁性を備えた枕状部材１５ｂの挿入によっても、前記短絡が防止できる。なお、この枕状部材１５ｂは、流動性がある状態で隙間に注入した後に固化させても良い。
【００９４】
前記第２の実施形態は、単に各単位積層電極１を複数枚積層したものであるが、取り扱いの容易性あるいは作業性を考慮すれば、この単位積層電極１の束を、予めアルミラミネートフィルム等の絶縁性フィルム１０により覆い、密封シールした状態で芯材２の周囲に巻回しても良い。この場合も、絶縁性フィルム１０からは集電体３あるいは端部集電体９に接続されたリード線を出しておくことが好ましい。
【００９５】
このように絶縁性フィルム１０により覆われた単位積層電極１の束を芯材２に巻きつける場合には、芯材２の曲率が大きい方が作業性は良いが、この曲率は単位積層電極１の束の厚さ、長さとの関係から適宜設定する。
【００９６】
また、前記絶縁性フィルム１０により単位積層電極１の束をシールするとき、巻き付けやすいように曲率をもったヒーターのシーラーでヒートシールすれば、後の巻き付け作業も行ないやすい。
【００９７】
上述したように、単位積層電極１を積層した積層部材Ｓの長さ方向断面形状が曲率を持つものを、バイポーラー電池として用いれば、電気自動車、ハイブリッド電気自動車、燃料電池車、内燃機関車用の電源として極めてコンパクトなものとすることができる。
＜実施例＞
本発明の効果を、以下の実施例および比較例を用いて説明する。ただし、本発明の技術的範囲が以下の実施例に限定されるものではない。
【００９８】
＜実施例１＞
集電体として、厚さ２０μｍのアルミニウム箔を用いて、図２、３に示すバイポーラー電極Ｐを作製する。電極の幅としては、図２に示すように、正極活物質層４の幅Ｗを電極の幅とし、集電体３の正極活物質層４より突出部分の幅を３ｍｍとする。
【００９９】
１．負極活物質層５の作製
まず、集電体３上に負極活物質層５を形成する。負極活物質としてＬｉ₄Ｔｉ₅Ｏ₁₂を準備した。この二次粒子の平均粒径は１０μｍで、０．２〜０．５μｍの一次粒子がある程度ネッキングした構造になっていた。
【０１００】
前記負極活物質［２８質量％］、導電助剤としてアセチレンブラック［３質量％］、前記高分子原料［１７質量％］、リチウム塩としてＢＥＴＩ［８質量％］、熱重合開始剤としてアゾビスイソブチロニトリル［高分子原料に対して０．１質量％］、および、溶媒としてＮＭＰ［４４質量％］を含む溶液を充分に撹拌して、スラリーを得た。
【０１０１】
該スラリーを、集電体３の一方の面上にコーターで塗布した。真空乾燥機中にて、９０℃で２時間以上、スラリーが塗布されたアルミニウム箔を加熱乾燥し、一方の面上に負極活物質層５が形成された集電体３を得た。
【０１０２】
２．正極活物質層４の作製
次に、同集電体３の反対側の面上に正極活物質層４を形成した。
【０１０３】
平均粒子径２μｍのスピネルＬｉＭｎ₂Ｏ₄を正極活物質として準備した。
【０１０４】
前記正極活物質［２９質量％］、導電助剤としてアセチレンブラック［８．７質量％］、前記高分子原料［１７質量％］、リチウム塩としてＢＥＴＩ［７．３質量％］、熱重合開始剤としてアゾビスイソブチロニトリル［高分子原料に対して０．１質量％］、および、溶媒としてＮＭＰ［４１質量％］を含む溶液を充分に撹拌して、スラリーを得た。該スラリーを、前記一方の面上に負極活物質層等が形成された集電体３の、他方の面上にダイコーターを用いて集電体３の周辺部がのこるような図２に示すパターン様式で塗布した。真空乾燥機中にて、９０℃で２時間以上、加熱乾燥し、一方の面上に負極活物質層５が、他方の面上に正極活物質層４が形成されたバイポーラー電極Ｐを得た。
【０１０５】
３．高分子固体電解質層６の作製
前記負極活物質層５上に高分子電解質層６を形成した。
【０１０６】
高分子電解質としては、Ｊ．Ｅｌｅｃｔｒｏｃｈｅｍ．Ｓｏｃ．，１４５（１９９８）１５２１に記載の方法に従って合成されたポリエーテル形のネットワーク高分子を高分子原料として準備した。
【０１０７】
前記高分子原料［５３質量％］、リチウム塩としてＬｉＮ（ＳＯ₂Ｃ₂Ｆ₅）₂（以下、「ＢＥＴＩ」と記載）［２６質量％］、光重合開始剤としてベンジルジメチルケタール［高分子原料に対して０．１質量％］、および、溶媒としてドライアセトニトリルを含む溶液を調製したあとアセトニトリルを真空蒸留で除いた。ダイコーターを用いて、前記負極活物質層５上にこの粘性の高い溶液をパターン塗布し、その上を剥離剤をコートしたＰＥＴフィルムで覆い、紫外線を照射して光重合（架橋）した。作製された膜を真空容器に入れ、９０℃の高真空下で１２時間、膜を加熱乾燥し、溶媒を除去した。得られた高分子固体電解質層６は、弾性に富み、強い粘着性を有していた。
【０１０８】
４．成形
次に、先に製造した単位積層電極１を成形し、電池とする。各単位積層電極１ａ〜１ｅの正極活物質層４の長さＬは１００ｃｍとした。表面を絶縁塗装したアルミニウム製の円筒状芯材２を回転軸に固定し、図４示すように、芯材２の周りに単位積層電極１ａ〜１ｅをセットした。この場合、ＰＥＴフィルムを剥がして、各始端が一致して巻き込まれるようにセットした。
【０１０９】
同様にして集電体３，３（通常の薄肉のもの）間に絶縁層８が位置するようにセットした。この絶縁層８は巻回したとき各積層部材Ｓが重なるときの短絡を防止する。
【０１１０】
そして、円筒状芯材２を回転すると、セットされた単位積層電極１ａ〜１ｅの巻き始めから絶縁層８も貼り付けた。
【０１１１】
この単位積層電極１ａ〜１ｅの巻き付けが完了した時の終端上に保持手段７であるカプトン粘着テープを巻いて、単位積層電極１ａ〜１ｅ等が動かないように固定した。
【０１１２】
端部の集電体３からリード線１２が外部に突出するように、アルミニウム製の円筒状芯材２を含めて、アルミニウム製の絶縁性フィルム１０により密封した。
【０１１３】
＜実施例２＞
実施例２は、実施例１において、端部の集電体３，３を厚さ３０μｍのアルミニウム製の端部集電体９，９とした以外は実施例１と同様のバイポーラー電池とした。
【０１１４】
＜実施例３＞
実施例３は、実施例１と同様なアルミニウム製の円筒状芯材２の外表面上に、図９に示す段差防止用のゴムを貼り付けた状態で、１０セル分の単位積層電極１を重ねて巻いた。単位積層電極１の巻き始めの部分が膨らんで、この部分に過大な圧力がかかる虞がなくなり、スムーズに巻けた。この積層部材Ｓを実施例１と同様に成形してバイポーラー電池とした。
【０１１５】
＜実施例４＞
図７に示すような平坦形状のものであって、長さ１００ｃｍの単位積層電極１を６層重ねてアルミニウムの絶縁性フィルム１０に封入し、最上段と最下段の端部集電体９からリード線１２を取り出した。この絶縁性フィルム１０に封入した積層部材Ｓを、実施例１と同様なアルミニウム製の円筒状芯材２に巻きつけて、最外周を保持手段７であるテフロン（登録商標）の粘着テープで固定して、バイポーラー電池とした。
【０１１６】
＜比較例１＞
比較例１は、図７に示すような積層部材Ｓを絶縁性フィルムで密封した平板状の電池とした。
【０１１７】
実施例と比較例の各電池を、単セル当り１Ｖと２．７Ｖの間で充放電して、充電状態で交流インピーダンス法により内部抵抗を測定した。
【０１１８】
電池の内部抵抗としては、周波数０．１Ｈｚでのインピーダンスの実部の値を採用した。各電池で求めた内部抵抗を単セルの単位面積あたりに換算して、その値について、比較例の場合を１．００として比を表１に示した。
【０１１９】
【表１】

【０１２０】
表１からわかるように、本発明によれば、単位積層電極１が曲率を有する構造とすることにより、電極と電解質間の密着性を良好にできるため、電池の内部抵抗を低くできることが分かった。
【０１２１】
本発明は、上述した実施形態のみに限定されるものではなく、図２に示す単位積層電極１において、高分子固体電解質層６を正極活物質層４あるいは負極活物質層５の上にそれぞれ形成した場合でも、密着性を向上させることができる。また、バイポーラー電池の電気容量を増加する場合には、巻回構造のバイポーラー電池は、巻く単位積層電極１の長さを長くするだけで、容量を容易に増大させることができるのは言うまでもない。
【図面の簡単な説明】
【図１】本発明の実施形態の一部破断概略斜視図である。
【図２】単位積層電極等の平面図である。
【図３】図２の３−３線に沿う断面図である。
【図４】図１の４−４線に沿う断面相当図である。
【図５】図４の５−５線に沿う概略断面図である。
【図６】本発明方法の第１の実施形態の要部を示す概略説明図である。
【図７】本発明方法の第２の実施形態における積層部材を示す概略断面図である。
【図８】段差防止手段の一例を示す概略断面図である。
【図９】段差防止手段の他の例を示す概略断面図である。
【符号の説明】
１，１ａ〜１ｅ…単位積層電極、
２…芯材、
３…集電体、
４…正極活物質層、
５…負極活物質層、
６…高分子固体電解質層、
７…保持手段、
８…絶縁層、
９…端部集電体、
１０…絶縁性フィルム、
１１…始端位置調節部材、
１５，１５ａ，１５ｂ…段差防止手段。
Ｍ…積層部材の内部空間、
Ｐ…バイポーラー電極、
Ｓ…積層部材、
Ｗ…幅。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bipolar battery in which a positive electrode active material and a negative electrode active material are disposed on both sides of a current collector. More specifically, the present invention relates to a bipolar battery using a polymer solid electrolyte substantially free of a solution as an electrolyte. The present invention relates to a polar battery, a manufacturing method thereof, and a vehicle.
[0002]
[Prior art]
In recent years, lithium ion secondary batteries capable of achieving high energy density and high output density have been developed and used as large-capacity power sources for electric vehicles and the like. The basic configuration of a lithium ion secondary battery is that a positive electrode in which a positive electrode active material such as lithium cobaltate and a conductive additive such as acetylene black are applied to an aluminum current collector using a binder, and carbon fine particles are bound to a copper current collector. A negative electrode coated with a resin is placed through a polyolefin-based porous membrane separator, and LiPF₆The non-aqueous electrolyte containing etc. is satisfy | filled.
[0003]
When a lithium ion secondary battery is used as a power source for an electric vehicle or the like, it is necessary to use a plurality of secondary batteries connected in series in order to ensure a large output. A battery module unit in which the cells (cells) of the basic configuration are connected in series, and further this battery module unit is connected in series to be used as an assembled battery.
[0004]
However, when a battery is connected via the connection portion, the output is reduced due to the electrical resistance of the connection portion. Further, the battery having the connection portion has a disadvantage in terms of space. That is, the output density and energy density of the battery are reduced depending on the volume occupied by the connection portion.
[0005]
As a solution to this problem, a bipolar battery with reduced cell connection resistance and a compact size has been proposed (for example, see Patent Document 1).
[0006]
In this bipolar battery, a so-called clad material obtained by rolling two types of metal foil as a current collector is used, and liquid is used for the electrolyte. Therefore, a hermetic seal in each cell is indispensable. A liquid junction can occur. Therefore, when a polymer solid electrolyte is used instead of the electrolytic solution, a hermetic seal is not required and a realistic bipolar battery can be obtained.
[0007]
As an example having such a structure, a positive electrode active material layer is disposed on one surface of a conductive substrate and a negative electrode active material layer is disposed on the other surface to form a bipolar electrode, and this electrode is interposed via a polymer solid electrolyte layer. A bipolar battery having a structure in which a plurality of layers are stacked, that is, a bipolar battery in which a plurality of positive electrode active materials 6, solid electrolytes 4, negative electrode active materials 7, and conductive substrate bodies 5 are stacked has also been proposed (for example, see Patent Document 2). .)
[0008]
In this bipolar battery, the conductive substrate, the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer are extremely thin in order to increase the utilization factor of the active material. For example, the conductive substrate is 0.5 μm, the positive electrode active material layer is 1 μm, the negative electrode active material layer is 1.5 μm, and the electrolyte layer is about 1 μm.
[0009]
[Patent Document 1]
JP-A-8-7926 (paragraphs “0007” to “0009”, FIGS. 1 and 2)
[Patent Document 2]
Japanese Utility Model Publication No. 4-54148 (FIG. 2)
[0010]
[Problems to be solved by the invention]
However, it is very troublesome to stack such thin members while ensuring mutual adhesion. In particular, the solid electrolyte has a lower ionic conductivity than the gel electrolyte, and if the adhesion between the electrode layer and the polymer solid electrolyte layer is not sufficiently maintained, the ionic conductivity is further reduced. There is also a possibility that the resistance may increase at the portion.
[0011]
In order to secure this adhesion, for example, a laminated member can be put in a case or the like, and pressure can be applied to the laminated member by an elastic body. Applying pressure is cumbersome and difficult. In addition, if either the electrolyte layer or the electrode layer has adhesiveness, the adhesion is improved. However, in order to maintain the adhesion over a long period of time in this way, the pressure is again applied by some method. It is necessary to keep hanging.
[0012]
In view of these problems, the present invention provides a bipolar battery that can maintain adhesion between electrode layers and electrolyte layers without separately providing a means for applying pressure to a molded laminated member. This is the first purpose.
[0013]
A second object of the present invention is to provide a method for manufacturing the same bipolar battery.
[0014]
A third object of the present invention is to provide a vehicle equipped with the bipolar battery.
[0015]
[Means for Solving the Problems]
The object of the present invention is achieved by the following means.
[0016]
  (1) In a bipolar battery formed by laminating a unit laminated electrode in which a polymer solid electrolyte layer is provided on a bipolar electrode having a positive electrode active material layer on one surface and a negative electrode active material layer on the other surface,An arc shape or an annular shape, and a core material provided with a recess on the surface;Laminating at least two unit laminated electrodes having a predetermined width and lengthThen, one end thereof is inserted into the recess and wound around the core material,Cross-sectional shape with curvatureAnd a laminated memberA bipolar battery characterized by that.
(2) In a bipolar battery in which a unit laminated electrode in which a polymer solid electrolyte layer is provided on a bipolar electrode having a positive electrode active material layer on one surface and a negative electrode active material layer on the other surface,
An arc-shaped or annular core material;
A laminated member having a cross-sectional shape with a curvature, wherein at least two layers of the unit laminated electrodes having a predetermined width and length are laminated and wound around the core material;
A bipolar battery comprising: an insert provided between a winding start end of the laminated member and a winding layer on the outer periphery thereof.
[0017]
  (3The laminated member is provided with an insulating layer that prevents electrical continuity between the laminated members that are superposed on each other.Or (2)Bipolar battery.
[0018]
  (4The laminated member is provided with holding means for holding a cross-sectional shape having the curvature.~ (3)Bipolar battery.
[0020]
(5) The laminated member is provided with an end collector that is thicker than other collectors on the outer peripheral surface of the outermost layer and the inner peripheral surface of the innermost layer. The bipolar battery according to any one of (1) to (4) above.
[0021]
(6) The bipolar battery according to any one of (1) to (5) above, wherein a heating element is provided in an internal space of the laminated member having a cross-sectional shape having the curvature.
[0022]
  (7) In a method for manufacturing a bipolar battery comprising a bipolar electrode having a positive electrode active material layer on one side of a current collector and a negative electrode active material layer on the other side and a unit laminated electrode provided with a polymer solid electrolyte layer. ,In the core material that has an arc shape or an annular shape, and a concave portion is formed on the outer peripheral surface,A laminated member in which at least two layers of the unit laminated electrodes having a predetermined width and length are laminated,Put one end of the recess into the recessA method of manufacturing a bipolar battery, wherein the bipolar battery is closely wound around an outer peripheral surface of a core material.
(8) In a method for manufacturing a bipolar battery comprising a bipolar electrode having a positive electrode active material layer on one side of a current collector and a negative electrode active material layer on the other side and a unit laminated electrode provided with a polymer solid electrolyte layer. A winding member in which at least two or more of the unit laminated electrodes having a predetermined width and length are laminated on an outer peripheral surface of an arc-shaped or annular core member, and a winding start end portion and an outer winding layer thereof A method for manufacturing a bipolar battery, comprising inserting an insert between the two and winding it closely.
[0023]
  (9The laminated member is characterized in that an insulating layer for preventing electrical conduction is provided between the overlapping layers.(7) or (8)Manufacturing method of bipolar battery.
[0024]
  (10The laminated member is provided with holding means for holding the shape having the curvature.(7)-(9)Manufacturing method of bipolar battery.
[0025]
  (11The above-mentioned laminated member is characterized in that the starting end of each unit laminated electrode is formed into a polymerized state at the same position when a plurality of unit laminated electrodes are formed into an annular shape.7) ~ (10) Bipolar battery manufacturing method.
[0026]
  (12The unit laminated electrode includes an insulating start end position adjusting member that adjusts the start end position.11) Bipolar battery manufacturing method.
[0027]
  (13The laminated member is formed by winding a whole bundle of a plurality of layers in which the unit laminated electrodes are overlapped with an insulating film and winding the wound around the outer peripheral surface of the core material.(7)~(12)Manufacturing method of bipolar battery.
[0029]
(14) The bipolar battery manufacturing method according to (13), wherein the step prevention means is a recess formed in an outer peripheral surface of the core member.
[0031]
  (14)(1) to (6)Connect one or more bipolar batteries as power sourceIt is characterized byvehicle.
[0032]
【The invention's effect】
  Claim 1And 2Since the laminated member has a cross-sectional shape with a curvature, the unit laminated electrode constituting the laminated member has the unit laminated shape from the shape without providing a means for applying pressure to the molded laminated member. Adhesiveness between the electrode layers and the electrolyte layers between the electrodes can be maintained, and a high-performance bipolar battery in which a decrease in ion conductivity and an increase in internal resistance are prevented can be obtained. Moreover, if the cross-sectional shape having a curvature is formed by winding, the capacity of the battery can be adjusted by the winding amount or the winding length, and further, the core material is taken from the inside of the wound laminated member. If it is removed, a shape can be set freely in terms of shape.Then, the core material is provided with a small portion or an insert as a step preventing means for preventing a step from occurring between the winding start end of the laminated member and the wound layer on the outer periphery thereof. Thus, it is possible to reliably prevent a short circuit that is likely to occur at the stepped portion.
[0033]
  Claim3According to the invention, since the insulating layers for preventing electrical conduction are provided between the laminated members that are overlaid, a short circuit due to the overlapping of the layers is prevented, and a more safe bipolar battery is obtained.
[0034]
  Claim4In this invention, if the cross-sectional shape of the laminated member having a curvature is held by the holding means, the performance of the bipolar battery in which the decrease in ion conductivity and the increase in internal resistance are prevented can be maintained in a high state.
[0036]
In the invention of claim 5, since the end collectors thicker than the other collectors are provided at the outermost part and the innermost part, the resistance in the surface direction of the collectors is determined from the current flow of the bipolar battery. The impedance at each part of the battery can be made comparable.
[0037]
In the invention of claim 6, since the heating element is provided in the internal space of the laminated member, the polymer solid electrolyte layer can be activated, the flow of current can be made smooth, and the performance of the battery can be improved.
[0038]
  In the inventions of claims 7 and 8, since the laminated member in which at least two unit laminated electrodes are laminated is tightly wound around the outer peripheral surface of the arc-shaped or annular core material, A laminated member having a curvature can be easily formed, and the manufacture of a bipolar battery becomes extremely easy.In addition, since the core member is provided with a recess or an insert as a step preventing means so as not to cause a step between the winding start end portion of the laminated member and the outer peripheral winding layer, the core member is wound. It is possible to reliably prevent a short circuit that is likely to occur at the step portion.
[0039]
  Claim9In the present invention, if an insulating layer for preventing electrical conduction is provided between the overlapping layers of the laminated members, a short circuit due to the overlapping of the layers can be prevented, and a highly safe bipolar battery can be manufactured very easily.
[0040]
  Claim10According to the invention, if the cross-sectional shape of the laminated member having a curvature is held by the holding means, a high-performance bipolar battery in which a decrease in ion conductivity and an increase in internal resistance are prevented can be manufactured very easily.
[0041]
Claim11In the invention of the present invention, it is possible to easily form a laminated member even with a thin material if it is tightly wound around the outer peripheral surface of the core material so that the starting ends of the plurality of unit laminated electrodes are in a polymerized state at the same position, The adhesion between the wound layers is also improved.
[0042]
  Claim12According to the invention, if an insulating starting end position adjusting member is provided on each unit laminated electrode, there is no step between the wound layers, and winding can be performed smoothly, and adhesion is improved.
[0043]
  Claim13According to the invention, if a bundle of a plurality of layers in which unit laminated electrodes are overlapped and covered with an insulating film is wound around the outer peripheral surface of the core material, handling and winding work of the laminated member is easy and workability is improved. Will improve. In particular, if heat sealing is performed with a heat sealer, winding can be further simplified.
[0045]
  Claim14If a bipolar battery that is small, lightweight, has good moldability, and is not strictly specified in shape is mounted on a vehicle such as an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, or an internal combustion engine vehicle, the space In terms of vehicle performance, it can be used as an effective power source, saving energy and greatly contributing to environmental sanitation.
[0046]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0047]
1 is a partially broken schematic perspective view of an embodiment of the present invention, FIG. 2 is a plan view of a unit laminated electrode and the like, and FIG. 3 is a cross-sectional view taken along line 3-3 of FIG.
[0048]
In FIG. 1, the bipolar battery of this embodiment will be outlined. Basically, a laminated member S in which two or more unit laminated electrodes 1 are laminated is wound around a cylindrical core material 2 to have a cross-sectional shape. I try to have a curvature.
[0049]
In the present specification, the unit laminated electrode 1 is a bipolar having a positive electrode active material layer 4 on one surface and a negative electrode active material layer 5 on the other surface as shown in FIGS. The electrode P is obtained by laminating the polymer solid electrolyte layer 6, and the laminated member S is obtained by laminating at least two unit laminated electrodes.
[0050]
Thus, when the laminated member S is wound around the core material 2 having a curved surface, each layer of the laminated member S formed around the core material 2 has a shape in which the cross-sectional shape perpendicular to the axis has a curvature. As a result, the laminated member S can maintain the adhesion between the unit laminated electrodes 1 without applying pressure, and the decrease in ion conductivity and the increase in internal resistance are prevented.
[0051]
4 is a cross-sectional equivalent view taken along line 4-4 of FIG. 1. In FIG. 4, the laminated member S in which a plurality of unit laminated electrodes 1 are laminated is shown as one line, and FIG. 4 is a schematic cross-sectional view taken along line 5-5 of FIG. 4 and mainly shows only one laminated member S in detail.
[0052]
Basically, as shown in FIG. 2, this bipolar battery has a large number of strip-shaped unit laminated electrodes 1 each having a predetermined width W and length L, and at least two or more layers are laminated by a predetermined method. Thus, the laminated member S is formed. The stacking method may be simply stacked, or a method described in detail later may be used. Then, as shown in FIG. 4, the laminated member S is wound around the cylindrical core material 2 so that the cross-sectional shape in the length direction has a curvature. To maintain this shape, tape or adhesive is used. It is held by appropriate holding means 7 such as an agent.
[0053]
If the laminated member S is wound so as to have a cross-sectional shape having a curvature, the capacity of the battery can be adjusted by the amount of winding or the length of winding, and in some cases, the inside of the wound laminated member S If the core material is removed from, the entire shape can be freely deformed, and the shape can be freely set.
[0054]
However, if the laminated member S is wound so as to be stacked around the core material 2, there is a possibility of electrical conduction between the respective layers. It is preferable to provide it. The insulating layer 8 insulates the wound unit laminated electrode 1 so that the layer of the unit laminated electrode 1 does not contact the adjacent layer. Examples of the insulating layer 8 to be used include a Kapton adhesive film, a polyester adhesive film, and a polyolefin adhesive film.
[0055]
In the bipolar battery, the current flows through the solid polymer electrolyte layer 6 from the positive electrode active material layer 4 toward the negative electrode active material layer 5 as indicated by an arrow in FIG. That is, since it flows so as to penetrate through the laminated member S, the wound laminated member S has the thickness T of the end current collector 9 positioned at the outermost part and the innermost part of the laminated member S as another current collector. It is preferable to make it thicker than the wall thickness t of 3. In this way, the resistance of the current flowing in the surface direction of the end current collector 9 can be reduced, and the impedance in each part of the battery can be made comparable.
[0056]
The laminated member S may be entirely covered with an insulating film 10 such as a laminated film. In this way, the bipolar battery is not unnecessarily leaked, current can be taken out efficiently, and the battery also has a long life, which is preferable.
[0057]
In addition, when a heating element (not shown) is provided in the internal space M of the core member 2, the heat of the heating element can activate the solid polymer electrolyte layer, smooth the current flow, and improve the battery performance. . In addition, as a heat generating body, although it changes with the target objects which use a battery, in a hybrid car with an engine and a motor, an engine muffler etc. can be considered, for example.
[0058]
Further, the constituent elements of the unit laminated electrode 1 will be described individually, and the battery manufacturing method will be described.
[0059]
<Current collector>
The current collector 3 has a surface material of aluminum. When the surface material is aluminum, an active material layer having high mechanical strength is obtained even when the formed active material layer contains a polymer solid electrolyte. If the surface material is aluminum, the collector 3 will not be specifically limited about the structure. The current collector 3 may be aluminum itself. Moreover, the form by which the surface of the electrical power collector 3 was coat | covered with aluminum may be sufficient. That is, a current collector in which aluminum is coated on the surface of a substance other than aluminum (such as copper, titanium, nickel, SUS, or an alloy thereof) may be used. In some cases, a current collector in which two or more plates are bonded together may be used. From the viewpoint of corrosion resistance, ease of production, economy, and the like, it is preferable to use an aluminum foil alone as a current collector.
[0060]
<Positive electrode active material layer>
The positive electrode active material layer includes a positive electrode active material and a polymer solid electrolyte. In addition to this, a lithium salt may be included to increase ionic conductivity, and a conductive auxiliary agent may be included to increase electronic conductivity.
[0061]
As the positive electrode active material, a composite oxide of transition metal and lithium, which is also used in a solution-type lithium ion battery, can be used. Specifically, LiCoO₂Li / Co complex oxides such as LiNiO₂Li / Ni composite oxides such as spinel LiMn₂O_FourLi · Mn based complex oxide such as LiFeO₂And Li / Fe-based composite oxides. In addition, LiFePO_FourTransition metal and lithium phosphate compounds and sulfuric acid compounds; V₂O_Five, MnO₂TiS₂, MoS₂, MoO_ThreeTransition metal oxides and sulfides such as PbO₂, AgO, NiOOH and the like.
[0062]
The particle size of the positive electrode active material may be smaller than the particle size generally used in solution-type lithium ion batteries in which the electrolyte is not solid in order to reduce the electrode resistance of the bipolar battery.
[0063]
<Polymer solid electrolyte>
The polymer solid electrolyte is not particularly limited as long as it is a polymer having ion conductivity. Examples of the polymer having ion conductivity include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. Such polyalkylene oxide polymer is LiBF._Four, LiPF₆, LiN (SO₂CF_Three)₂, LiN (SO₂C₂F_Five)₂Lithium salt such as can be dissolved well. In addition, excellent mechanical strength is exhibited by forming a crosslinked structure.
[0064]
In the present invention, the polymer solid electrolyte is contained in at least one of the positive electrode active material layer and the negative electrode active material layer. However, in order to further improve the battery characteristics of the bipolar battery, it is preferable to be included in both.
[0065]
As the lithium salt, LiBF_Four, LiPF₆, LiN (SO₂CF_Three)₂, LiN (SO₂C₂F_Five)₂Or a mixture thereof. However, it is not necessarily limited to these.
[0066]
Examples of the conductive assistant include acetylene black, carbon black, and graphite. However, it is not necessarily limited to these.
[0067]
<Negative electrode active material layer>
The negative electrode active material layer includes a negative electrode active material and a polymer solid electrolyte. In addition to this, a lithium salt may be included to increase ionic conductivity, and a conductive auxiliary agent may be included to increase electronic conductivity. Except for the type of the negative electrode active material, the contents are basically the same as those described in the section “Positive electrode active material”, and thus the description thereof is omitted here.
[0068]
As the negative electrode active material, a negative electrode active material that is also used in a solution-type lithium ion battery can be used. However, since a polymer solid electrolyte is used in the bipolar battery of the present invention, a metal oxide or a composite oxide of metal and lithium is preferable in consideration of reactivity with the polymer solid electrolyte. More preferably, the negative electrode active material is a transition metal oxide or a composite oxide of a transition metal and lithium. More preferably, the transition metal is titanium. That is, the negative electrode active material is more preferably titanium oxide or a composite oxide of titanium and lithium.
[0069]
<Polymer solid electrolyte layer>
The polymer solid electrolyte layer is a layer composed of a polymer having ion conductivity, and the material is not limited as long as it exhibits ion conductivity. As the polymer solid electrolyte, polyethylene oxide (PEO), polypropylene oxide (PPO), and their copolymer polymers are used, and the raw material polymer having a crosslinkable carbon-carbon double bond in the molecule is used. Examples thereof include polymer solid electrolytes synthesized by radical polymerization.
[0070]
The polymer solid electrolyte layer contains a lithium salt in order to ensure ionic conductivity. As the lithium salt, LiBF_Four, LiPF₆, LiN (SO₂CF_Three)₂, LiN (SO₂C₂F_Five)₂Or a mixture thereof. However, it is not necessarily limited to these. Polyalkylene oxide polymers such as PEO and PPO are LiBF_Four, LiPF₆, LiN (SO₂CF_Three)₂, LiN (SO₂C₂F_Five)₂Lithium salt such as can be dissolved well. Moreover, excellent mechanical strength is exhibited by forming a crosslinked structure.
[0071]
The polymer electrolyte membrane is, for example, polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof, and is a raw material polymer having a crosslinkable carbon-carbon double bond in the molecule. The lithium salt can be dissolved in a solvent such as NMP, poured into a light-transmitting gap whose thickness is determined by a spacer, and irradiated with ultraviolet rays to form a thin film. However, the method is not limited to this method. A polymer electrolyte membrane can also be produced by radiation polymerization, electron beam polymerization, or thermal polymerization. In the case of ultraviolet polymerization, an appropriate photopolymerization initiator may be used, and in the case of the thermal polymerization method, a thermal polymerization initiator may be used. As a lithium salt to be dissolved, LiBF_Four, LiPF₆, LiN (SO₂CF_Three)₂, LiN (SO₂C₂F_Five)₂And a mixture of two or more of these can be used, but is not limited thereto.
[0072]
<Production of unit laminated electrode>
In order to configure the unit laminated electrode 1 according to this embodiment, first, the raw material polymer in the negative electrode active material layer 5 described above, the negative electrode active material, the conductive additive, the lithium salt, the solvent, and a small amount of azobisisobutyrate. A slurry is prepared from a thermal polymerization initiator such as nitrile (AIBN), and this is applied to one surface of the current collector 3 and heated to prepare the negative electrode active material layer 5.
[0073]
Next, the positive electrode active material layer 4 is formed on the other surface of the current collector 3 in the same manner, whereby the bipolar electrode P is manufactured. The order of forming the positive electrode active material layer 4 and the negative electrode active material layer 5 may be reversed.
[0074]
A polymer solid electrolyte layer 6 is formed on the bipolar electrode P. In this formation, a solution containing a lithium salt, a raw material polymer, and an ultraviolet polymerization initiator is directly applied on the unit laminated electrode 1 and covered with a transparent film such as PET and irradiated with ultraviolet rays for 10 to 20 minutes. Thus, the unit laminated electrode 1 can be formed.
[0075]
As a result, as shown in FIG. 3, the unit laminated electrode 1 formed in the order of the polymer solid electrolyte layer 6, the negative electrode active material layer 5, the current collector 3, and the positive electrode active material layer 4 is formed from the bottom. The
[0076]
Insulating layers (shown by alternate long and short dash lines) may be provided on both sides of the current collector 3 to insulate the unit laminated electrodes 1 from each other.
[0077]
<Production method of bipolar battery>
The first embodiment of the present manufacturing method is a method of manufacturing a bipolar battery in which a plurality of unit laminated electrodes 1 are laminated one by one around a core material 2 to form a laminated member S. .
[0078]
The core material 2 used here may be any material as long as it has a curvature. For example, it may be simply an arc shape, a cylindrical ellipse, an annular shape, or the like. In particular, as a material that is more uniformly applied with a wrapping pressure and is lightweight, the width of the laminated member S in the axial direction may be used. That is, it is preferable that each unit laminated electrode 1 has a length approximately the same as the width W, and an axially perpendicular section made of aluminum has an arc shape or an annular shape. However, in order to increase the efficiency of the battery, it is preferable to cover the outer peripheral surface of the core material 2 with an insulating layer (not shown).
[0079]
FIG. 6 is a schematic explanatory view showing the main part of the first embodiment of the manufacturing method according to the present invention. When manufacturing a bipolar battery using this core material 2, in FIG. 6, it attaches to rotating shafts, such as a motor, first so that the axis line of the core material 2 may stand upright.
[0080]
In the present embodiment, five unit laminated electrodes 1 a to 1 e, outermost and innermost end

current collectors

9 and 9, and an insulating layer 8 are arranged around the core material 2.
[0081]
A plurality of rollers (not shown) for supplying the unit laminated electrode 1 are arranged around the core material 2, and an end portion is provided between the unit laminated electrodes 1 a and 1 e positioned at both ends of the unit laminated electrode 1. Rollers for supplying the current collector 9 and the insulating layer 8 are also arranged, and the winding operation is performed while supplying the unit laminated electrode 1 and the like by these rollers.
[0082]
In the winding operation, first the first unit laminated electrode 1a is wound around the core member 2, and then the starting end of the second unit laminated electrode 1b coincides with the starting end of the first unit laminated electrode 1a. And wound around the core material 2 while applying tension to each unit laminated electrode 1. Similarly, the unit laminated electrodes 1c to 1e are wound so that the start end and the end match.
[0083]
In this case, a starting end adjusting member 11 (see FIG. 2) such as an insulating adhesive film or the like is provided at the starting end portion of each unit laminated electrode 1, the length is adjusted, and an appropriate core material 2 for winding is provided. When pasting sequentially from the position, even when the starting ends are matched and wound in a layered manner, there is no step at the starting end, and smooth winding is possible. In addition, if this is done, it is possible to reliably prevent short-circuits that are likely to occur at the stepped portion, improve the adhesion between the wound layers, and prevent ion conductivity from decreasing and internal resistance from increasing.
[0084]
When the laminated member S is formed in this way, the holding means 7 holds the shape having the curvature, covers the outermost portion with the insulating film 10 and connects the lead wire 12 ( (See FIGS. 1 and 4).
[0085]
In this bipolar battery, the current flows through each unit laminated electrode 1 in each laminated member S, so that the unit laminated electrodes 1 are in close contact with each other. Decrease in ionic conductivity and increase in internal resistance are prevented, resulting in a high performance bipolar battery.
[0086]
When the current reaches the end current collector 9, the current flows along the surface of the end current collector 9, that is, along the circumferential direction, and is guided to the outside through the lead wire 12.
[0087]
Next, a second embodiment of the manufacturing method will be described.
[0088]
FIG. 7 is a cross-sectional view of a laminated member in which a plurality of unit laminated electrodes used in the second embodiment are stacked, and FIGS. 8 and 9 are cross-sectional views showing step prevention means.
[0089]
In the second embodiment, a plurality of unit laminated electrodes 1 having a predetermined width W and length are stacked in advance, and the stacked bundle is used as a laminated member S, and is densely wound around the outer peripheral surface of the core member 2. Like to do. The same core material 2 as in the above case is used, but if a plurality of unit laminated electrodes 1 previously laminated on the outer peripheral surface of the core material 2 are wound, a large number of unit laminated electrodes 1 are wound around the core material 2. Compared to the case of individual winding, it is possible to wind all at once, and the winding workability is improved.
[0090]
In this case, as the laminated member S, a member having a length of about 1 m is used, but when wound around the core material 2, a step is generated between the first and second rolls. In the present embodiment, it is preferable to provide the step prevention means 15 because there is a possibility that a short circuit may occur in the portion.
[0091]
The step prevention means 15 may be anything as long as it can eliminate the step, but in this embodiment, as shown in FIG. 8, by forming a recess 15 a on the outer peripheral surface of the core material 2. It is used as a means to prevent steps. If such a recess 15a is formed, the starting end of the first roll enters here, and even if the second roll is wound, the occurrence of a step between the two is prevented.
[0092]
In particular, when such a recess 15a is provided, winding of the laminated member S can be performed smoothly and quickly, and not only the workability is improved, but also tightening during winding is prevented. When the next layer is wound around the outer periphery of a step having a stepped portion, the first end of the first winding is strongly pressed and tightened by this tightening, and a short circuit occurs between the unit laminated electrodes 1 inside. However, such a short circuit can be surely prevented by forming the recess 15a.
[0093]
Further, other step prevention means as shown in FIG. 9 may be used. In the illustrated example, a pillow-shaped member 15b made of rubber or the like is inserted into the stepped portion, but the short circuit is prevented even by inserting the pillow-shaped member 15b having such an insulating property. it can. The pillow-shaped member 15b may be solidified after being poured into the gap in a fluid state.
[0094]
In the second embodiment, a plurality of unit laminated electrodes 1 are simply laminated. However, in consideration of ease of handling or workability, a bundle of unit laminated electrodes 1 is preliminarily formed of an aluminum laminated film or the like. It may be wound around the core material 2 in a state where it is covered with the insulating film 10 and hermetically sealed. Also in this case, it is preferable to lead out the lead wire connected to the current collector 3 or the end current collector 9 from the insulating film 10.
[0095]
When the bundle of unit laminated electrodes 1 covered with the insulating film 10 is wound around the core material 2, the larger the curvature of the core material 2, the better the workability, but this curvature is the unit laminated electrode 1. It is set as appropriate based on the relationship between the thickness and length of the bundle.
[0096]
Further, when the bundle of unit laminated electrodes 1 is sealed with the insulating film 10, if it is heat-sealed with a heater sealer having a curvature so that it can be easily wound, the subsequent winding work can be easily performed.
[0097]
As described above, if the laminated member S in which the unit laminated electrode 1 is laminated has a longitudinal sectional shape having a curvature, it can be used as a bipolar battery for an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, and an internal combustion locomotive. The power source can be extremely compact.
<Example>
The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples.
[0098]
<Example 1>
A bipolar electrode P shown in FIGS. 2 and 3 is produced using an aluminum foil having a thickness of 20 μm as a current collector. As shown in FIG. 2, the width of the electrode is set such that the width W of the positive electrode active material layer 4 is the width of the electrode, and the width of the protruding portion of the current collector 3 from the positive electrode active material layer 4 is 3 mm.
[0099]
1. Production of negative electrode active material layer 5
First, the negative electrode active material layer 5 is formed on the current collector 3. Li as negative electrode active material_FourTi_FiveO₁₂Prepared. The average particle diameter of the secondary particles was 10 μm, and the primary particles of 0.2 to 0.5 μm were necked to some extent.
[0100]
The negative electrode active material [28% by mass], acetylene black [3% by mass] as a conductive auxiliary, the polymer raw material [17% by mass], BETI [8% by mass] as a lithium salt, and azobisiso as a thermal polymerization initiator. A solution containing butyronitrile [0.1% by mass with respect to the polymer raw material] and NMP [44% by mass] as a solvent was sufficiently stirred to obtain a slurry.
[0101]
The slurry was applied on one surface of the current collector 3 with a coater. In a vacuum dryer, the aluminum foil coated with the slurry was heated and dried at 90 ° C. for 2 hours or longer to obtain a current collector 3 having a negative electrode active material layer 5 formed on one surface.
[0102]
2. Preparation of positive electrode active material layer 4
Next, the positive electrode active material layer 4 was formed on the surface on the opposite side of the current collector 3.
[0103]
Spinel LiMn with an average particle size of 2 μm₂O_FourWas prepared as a positive electrode active material.
[0104]
The positive electrode active material [29% by mass], acetylene black [8.7% by mass] as a conductive auxiliary, the polymer raw material [17% by mass], the lithium salt as BETI [7.3% by mass], a thermal polymerization initiator A solution containing azobisisobutyronitrile [0.1% by mass with respect to the polymer raw material] as N and [41% by mass] NMP as the solvent was sufficiently stirred to obtain a slurry. The slurry is shown in FIG. 2 in which the peripheral portion of the current collector 3 is left on the other surface of the current collector 3 having a negative electrode active material layer or the like formed on the one surface by using a die coater. Applied in a pattern mode. In a vacuum dryer, heat-dried at 90 ° C. for 2 hours or more to obtain a bipolar electrode P in which the negative electrode active material layer 5 is formed on one surface and the positive electrode active material layer 4 is formed on the other surface. It was.
[0105]
3. Preparation of polymer solid electrolyte layer 6
A polymer electrolyte layer 6 was formed on the negative electrode active material layer 5.
[0106]
Examples of the polymer electrolyte include J.M. Electrochem. Soc. , 145 (1998) 1521, a polyether type network polymer was prepared as a polymer raw material.
[0107]
The polymer raw material [53 mass%], LiN (SO₂C₂F_Five)₂(Hereinafter referred to as “BETI”) [26 mass%], after preparing a solution containing benzyldimethyl ketal [0.1 mass% based on polymer raw material] as a photopolymerization initiator and dry acetonitrile as a solvent Acetonitrile was removed by vacuum distillation. Using a die coater, this highly viscous solution was applied onto the negative electrode active material layer 5 in a pattern, covered with a PET film coated with a release agent, and irradiated with ultraviolet rays for photopolymerization (crosslinking). The produced film was put in a vacuum vessel, and the film was heated and dried under a high vacuum at 90 ° C. for 12 hours to remove the solvent. The obtained polymer solid electrolyte layer 6 was rich in elasticity and had strong adhesiveness.
[0108]
4). Molding
Next, the unit laminated electrode 1 manufactured previously is shape | molded and it is set as a battery. The length L of the positive electrode active material layer 4 of each unit laminated electrode 1a to 1e was 100 cm. An aluminum cylindrical core material 2 having an insulating coating surface was fixed to a rotating shaft, and unit laminated electrodes 1a to 1e were set around the core material 2 as shown in FIG. In this case, the PET film was peeled off, and set so that the respective starting ends were rolled up in unison.
[0109]
Similarly, the insulating layer 8 was set between the current collectors 3 and 3 (ordinary thin-walled ones). This insulating layer 8 prevents a short circuit when the laminated members S overlap when wound.
[0110]
And when the cylindrical core material 2 was rotated, the insulating layer 8 was also affixed from the start of winding of the set unit laminated electrodes 1a to 1e.
[0111]
The unit laminated electrodes 1a to 1e and the like were fixed so that the unit laminated electrodes 1a to 1e did not move by winding a Kapton adhesive tape as the holding means 7 on the end when the winding of the unit laminated electrodes 1a to 1e was completed.
[0112]
The lead wire 12 was sealed with an aluminum insulating film 10 including the aluminum cylindrical core material 2 so that the lead wire 12 protruded from the current collector 3 at the end.
[0113]
<Example 2>
Example 2 is a bipolar battery similar to Example 1 except that the

current collectors

3 and 3 at the end portions are aluminum end

current collectors

9 and 9 having a thickness of 30 μm. .
[0114]
<Example 3>
In Example 3, the unit laminated electrode 1 for 10 cells was formed on the outer surface of the aluminum cylindrical core material 2 similar to that in Example 1 with the rubber for preventing a step shown in FIG. I rolled it up. The winding start portion of the unit laminated electrode 1 swelled, and there was no possibility that excessive pressure was applied to this portion. This laminated member S was molded in the same manner as in Example 1 to obtain a bipolar battery.
[0115]
<Example 4>
7, the unit laminated electrode 1 having a length of 100 cm is stacked in six layers and enclosed in an aluminum insulating film 10, and the end current collectors 9 at the uppermost and lowermost stages are used. The lead wire 12 was taken out. The laminated member S encapsulated in the insulating film 10 is wrapped around the aluminum cylindrical core material 2 similar to that in the first embodiment, and the outermost periphery is fixed with a Teflon (registered trademark) adhesive tape as the holding means 7. Thus, a bipolar battery was obtained.
[0116]
<Comparative Example 1>
Comparative Example 1 was a flat battery in which a laminated member S as shown in FIG. 7 was sealed with an insulating film.
[0117]
Each battery of the example and the comparative example was charged / discharged between 1 V and 2.7 V per unit cell, and the internal resistance was measured by an AC impedance method in a charged state.
[0118]
As the internal resistance of the battery, the value of the real part of the impedance at a frequency of 0.1 Hz was adopted. The internal resistance obtained for each battery was converted per unit area of a single cell, and the ratio is shown in Table 1 with the value of the comparative example as 1.00.
[0119]
[Table 1]

[0120]
As can be seen from Table 1, according to the present invention, it was found that the unit laminated electrode 1 has a curvature so that the adhesiveness between the electrode and the electrolyte can be improved, so that the internal resistance of the battery can be lowered. .
[0121]
The present invention is not limited only to the above-described embodiment. In the unit laminated electrode 1 shown in FIG. 2, the polymer solid electrolyte layer 6 is formed on the positive electrode active material layer 4 or the negative electrode active material layer 5. Even if it does, adhesiveness can be improved. Further, when increasing the electric capacity of the bipolar battery, it goes without saying that the wound bipolar battery can easily increase the capacity only by increasing the length of the unit laminated electrode 1 to be wound. Yes.
[Brief description of the drawings]
FIG. 1 is a partially broken schematic perspective view of an embodiment of the present invention.
FIG. 2 is a plan view of unit laminated electrodes and the like.
3 is a cross-sectional view taken along line 3-3 in FIG.
4 is a cross-sectional equivalent view taken along line 4-4 of FIG.
5 is a schematic cross-sectional view taken along line 5-5 in FIG.
FIG. 6 is a schematic explanatory view showing the main part of the first embodiment of the method of the present invention.
FIG. 7 is a schematic cross-sectional view showing a laminated member in a second embodiment of the method of the present invention.
FIG. 8 is a schematic cross-sectional view showing an example of a step prevention means.
FIG. 9 is a schematic sectional view showing another example of the step preventing means.
[Explanation of symbols]
1, 1a to 1e ... unit laminated electrode,
2 ... Core material,
3 ... current collector,
4 ... positive electrode active material layer,
5 ... negative electrode active material layer,
6 ... polymer solid electrolyte layer,
7: Holding means,
8 ... Insulating layer,
9 ... End current collector,
10: Insulating film,
11 ... Start position adjusting member,
15, 15a, 15b ... Step prevention means.
M: Internal space of the laminated member,
P: Bipolar electrode,
S: Laminated member,
W ... Width.

Claims

In a bipolar battery in which a unit laminated electrode in which a polymer solid electrolyte layer is provided on a bipolar electrode having a positive electrode active material layer on one surface and a negative electrode active material layer on the other surface is laminated,
An arc shape or an annular shape, and a core material provided with a recess on the surface;
A laminated member having a cross-sectional shape with a curvature , wherein at least two unit laminated electrodes having a predetermined width and length are laminated , one end of which is inserted into the recess and wound around the core material ; A bipolar battery characterized by comprising:

In the bipolar battery formed by laminating a unit laminated electrode in which a polymer solid electrolyte layer is provided on a bipolar electrode having a positive electrode active material layer on one surface and a negative electrode active material layer on the other surface,
  An arc-shaped or annular core, and
  A laminated member having a cross-sectional shape having a curvature, wherein at least two or more of the unit laminated electrodes having a predetermined width and length are laminated and wound around the core material;
  A bipolar battery comprising: an insert provided between a winding start end of the laminated member and a winding layer on an outer periphery thereof.

The laminated member between respective lamination members each other that Kasaneawashi, bipolar battery according to claim 1 or 2, characterized in that an insulating layer for preventing electrical conduction.

The bipolar battery according to any one of claims 1 to 3, wherein the laminated member is provided with holding means for holding a cross-sectional shape having the curvature.

The laminated member is characterized in that end collectors thicker than other collectors are provided on the outer peripheral surface of the outermost layer and the inner peripheral surface of the innermost layer. The bipolar battery according to any one of claims 1 to 4 .

Bipolar battery according to any one of claims 1 to 5, characterized in that a heating element in the interior space of the laminated member which is a cross-sectional shape with the curvature.

In a method of manufacturing a bipolar battery, in which a unit laminated electrode in which a polymer solid electrolyte layer is provided on a bipolar electrode having a positive electrode active material layer on one surface and a negative electrode active material layer on the other surface is laminated,
A laminated member in which at least two or more layers of the unit laminated electrode having a predetermined width and length are laminated on a core member having an arc shape or an annular shape and having a concave portion formed on an outer peripheral surface, and one end portion of the concave portion is provided on the concave portion. method for manufacturing a bipolar battery, which comprises tightly wound around the outer peripheral surface of the core placed.

In a method of manufacturing a bipolar battery, in which a unit laminated electrode in which a polymer solid electrolyte layer is provided on a bipolar electrode having a positive electrode active material layer on one surface and a negative electrode active material layer on the other surface is laminated,
A laminated member in which at least two unit laminated electrodes having a predetermined width and length are laminated on an outer peripheral surface of a core material having an arc shape or an annular shape, a winding start end portion, a winding layer on the outer periphery thereof, A method of manufacturing a bipolar battery, comprising inserting an insert between the two and winding it closely.

9. The method for manufacturing a bipolar battery according to claim 7 , wherein the laminated member is provided with an insulating layer for preventing electrical conduction between the laminated members.

The method for manufacturing a bipolar battery according to claim 7, wherein the laminated member is provided with a holding unit that holds the shape having the curvature.

11. The laminated member according to any one of claims 7 to 10 , wherein a plurality of unit laminated electrodes are formed in a ring shape so that a starting end of each unit laminated electrode is in a superposed state at the same position. Manufacturing method of bipolar battery.

12. The method for manufacturing a bipolar battery according to claim 11 , wherein the unit laminated electrode includes an insulating start end position adjusting member for adjusting a start end position.

The lamination member may be any of claims 7-11, characterized in that the entire bundle of a plurality layers Kasaneawashi the unit laminate electrode obtained by covering the sealing of an insulating film is wound on the outer peripheral surface of the core material A method for producing a bipolar battery as described in 1. above.

Vehicle, characterized in that it has one or a plurality connected to power the bipolar battery according to any one of claims 1 to 6.